FR3146493A1 - SET FOR TURBOMACHINE AND ASSOCIATED TURBOMACHINE - Google Patents

Abstract

A turbomachine assembly comprising: - a fuel injector comprising an injector head (40) extending along a central axis (70), and - an injection system comprising a mixing bowl (50) and a ring (72) rotatable about said central axis, the assembly further comprising air supply means (64) inside the bowl, said ring (72) being shaped so as to reduce or increase by rotation an air passage section in said air supply means (64), the assembly comprising at least one controllable displacement device of said injector configured to move the injector head (40) along the central axis (70) between a first position and a second position, the assembly being configured to modify the angular position of said ring (72) relative to the air supply means (64) when the injector head (40) is moved between the first position and the second position. Abstract Figure: Figure 17A

Description

SET FOR TURBOMACHINE AND ASSOCIATED TURBOMACHINE

The present disclosure relates to a turbomachine assembly and an associated turbomachine. The turbomachine is in particular a turbomachine for aircraft.

As is known, an aircraft is propelled by turbomachines, for example turbojets or turboprops, shaped to receive an airflow at an upstream end. In the case of turbojets, this airflow is expelled at high speed at the rear end of the turbomachine to create the necessary thrust that moves the aircraft forward. In the case of turboprops, this airflow turns a turbine located at the rear of the turbomachine, which rotates a propeller located at the upstream end of the turbomachine. It is mainly the rotation of this propeller that creates the thrust that moves the aircraft forward when it uses turboprops.

A portion of the airflow received in each turbomachine is compressed in low-pressure and high-pressure compressors of the turbomachine, then passes through a combustion chamber installed therein. The combustion chamber typically has an annular shape about an axis of revolution and comprises a plurality of openings arranged regularly about this axis of revolution.

An injection system is arranged in each opening of the combustion chamber. Conventionally, the injection system comprises a mixing bowl and at least one auger arranged around a central axis of the injection system. The injection system is configured to introduce a portion of the compressed air flow into the combustion chamber. In order to ensure the permeability of the injection system to compressed air, the injection system comprises through holes arranged circumferentially around its central axis, for example on the auger and/or on the mixing bowl.

The injection system further comprises a cavity extending around the central axis and in which is received a head of a fuel injector which injects a flow of fuel into the combustion chamber. The injected fuel flow is sprayed and atomized by the flow of compressed air introduced by the air injection system, which gives rise to a mixture of air and fuel.

The turbomachine has several operating modes or phases, such as ignition, re-ignition, ground idle, take-off, flight idle or cruise. During the ignition or re-ignition phases of the turbomachine, the air-fuel mixture is ignited by means of a spark plug in the combustion chamber. Conversely, during the ground idle, take-off, flight idle or cruise phases of the turbomachine, the spark plug does not operate because combustion is maintained. The flame created during the ignition or re-ignition phases is in fact maintained by the supply of compressed air and fuel coming, respectively, from the air injection system and the injector head.

It should be noted that the turbomachine relighting conditions are critical. Indeed, the relighting of the turbomachine occurs when the flame in the combustion chamber goes out while the aircraft is in flight. Consequently, the low pressure and low temperature of the ambient air, the low temperature of the injected fuel, the variations in the viscosity of the fuel, and the high air flow speed in the combustion chamber constitute difficult conditions for relighting the combustion chamber that has gone out. A relight ceiling for the turbomachine is thus defined, which corresponds to the maximum altitude above sea level over a certain range of aircraft speed at which the combustion chamber can be relighted. Guaranteeing the relight ceiling specified by the aircraft manufacturer can be a significant technical challenge for the engine manufacturer.

It has been observed that moving the injector head forward into the combustion chamber improves fuel atomization in the combustion chamber and increases the reignition ceiling of the turbomachine. However, by moving the injector head forward into the combustion chamber, the injector is more exposed to high temperatures due to the flame maintained in the combustion chamber, which promotes premature wear of the injector head.

Furthermore, during the ignition and re-ignition phases, it may appear that the flame core initiated in front of the spark plug has difficulty reaching the fuel recirculation zone of the injection system or that the flame stagnates in front of an injection system without spreading to neighboring injection systems, which leads to a failure of ignition of the combustion chamber.

To improve this situation, it is known to reduce the permeability of the injection systems. However, reducing the permeability of the injection systems degrades the high-speed efficiency of the turbomachine and increases pollutant emissions.

In addition, injection systems were tested whose through holes did not have the same diameter, but with smaller through holes along axes distributed circumferentially around the mixing bowl. The aim was to optimize smoke emissions. These injection systems showed mixed results, with improvements on some turbomachine speeds and degradations on others.

Summary

This disclosure improves the situation.

For this purpose, a set is proposed for a turbomachine, in particular for an aircraft, the set comprising:
- a fuel injector comprising an injector head extending along a central axis, and
- an injection system comprising a mixing bowl mounted coaxially with the injector head, and a ring rotating around said central axis,
the assembly further comprising means for supplying air inside the bowl, these air supply means being regularly distributed around the central axis, said ring being shaped so as to reduce or increase by rotation an air passage section in said air supply means,
the assembly further comprising at least one controllable displacement device of said injector, the at least one controllable displacement device being configured to move the injector head between a first position in which the injector head is moved along said central axis in a first direction towards an outlet plane of the mixing bowl, and a second position in which the injector head is moved along said central axis in a second direction opposite to said first direction relative to the first position, the assembly being configured to modify the angular position of said ring relative to the air supply means when the injector head is moved between the first position and the second position.

Also, the assembly makes it possible to couple the movement between the first position and the second position of the injector head to the modification of the air passage section in the air supply means inside the mixing bowl. In particular, it is the movement of the injector head between the first and second positions which controls the rotation of the ring around the central axis of the injection system to increase or reduce the air passage section in the air supply means. It is thus possible to use the same signal to move the injector and the ring concomitantly. More precisely, the assembly described here can be configured so that the injector and the ring are moved both to the positions most conducive to the performance of the turbomachine when the latter operates in a given regime. For example, as will be detailed, in the ignition or re-ignition phase, it is advantageous to reduce the permeability of the injection system in order to enrich the combustion chamber with fuel, and to have the injector further into the combustion chamber so that the injected fuel is more penetrating into the combustion chamber. On the contrary, when the turbomachine is operating at full throttle, for example in the take-off phase, it is advantageous to increase the permeability of the injection system in order to impoverish the combustion chamber with fuel in order to reduce pollutant emissions, and to move the injector head away from the inside of the fuel chamber in order to prevent it from being thermally damaged. This will also be detailed below.

According to another aspect, the assembly is configured so that the angular position of said ring relative to the air supply means is modified so as to reduce the air passage section in said air supply means when the injector head is in the first position.

As indicated, in the first position, the injector head is moved along the central axis in a first direction towards an outlet plane of the mixing bowl, while in the second position, the injector head is moved along the central axis in a second direction opposite to the first direction. In other words, in the first position, the injector head is further recessed into the combustion chamber than in the second position. Thus, during the ignition or re-ignition phases, and as long as the turbomachine has not reached a speed higher than a determined speed, for example ground idle, the injector head can be advanced into the combustion chamber. The fuel is therefore injected into the combustion chamber at an injection angle making it possible to bring the fuel drops closer to the area where the spark plug of the combustion chamber deposits energy, thereby facilitating the ignition and re-ignition of the turbomachine. The re-ignition ceiling is therefore increased.

Furthermore, by advancing the injector head into the combustion chamber, the section of the through holes of the injection system through which the compressed air flows decreases, so that the speed of the compressed air entering the combustion chamber increases, which promotes the atomization of the fuel. Thus, in the ground idle phase, which represents 80% of a landing-takeoff cycle, better known as the LTO cycle (by its acronym in English "landing and take-off"), a more homogeneous mixture of air and fuel is obtained, which leads to a reduction in the pollutants generated.

Improved atomization also increases combustion efficiency, which helps reduce the amount of fuel consumed and the _CO2 emissions associated with combustion.

In addition, finer atomization has a positive impact on the stability of the combustion chamber, on the ability to ignite on the ground and to reignite at altitude, or even on the reduction of the appearance and deposition of coke on the injection system, which makes it possible to extend the service life of the injection system and the fuel injector.

Furthermore, by reducing the air passage section in the air supply means, the air permeability of the injection system is reduced. The fuel enrichment rate in the combustion chamber, defined as the ratio between a fuel flow rate injected into the chamber and an air flow rate injected into the chamber, is thus increased. This allows the flame core initiated in front of the spark plug to more easily reach the fuel recirculation zone of the injection system, and the flame generated in the chamber to propagate without difficulty to neighboring injection systems. The chances of successfully igniting the combustion chamber during the ignition or relighting phases of the turbomachine are thus increased. The relight ceiling of the turbomachine is also increased when the permeability of the injection system decreases.

At least for these reasons, the coupling of the positioning of the injector head in the first position and the reduction of the air passage sections in the air supply means proves advantageous when the turbomachine operates in ignition or re-ignition mode. Furthermore, all these advantages can be obtained without resorting to enriched injectors. Enriched injectors are injectors with increased permeability which allow more fuel flow to pass into the combustion chamber. Of course, in certain cases the injector of the assembly presented here can be an enriched injector.

Since the combustion chamber has several openings, each receiving an injection system, it is possible that some injection systems of the turbomachine are associated with an enriched injector, and other injection systems are associated with a non-enriched injector. This generates a hotter flame in the sector of the combustion chamber equipped with an enriched injector (due to the higher fuel flow) than in the sector of the combustion chamber equipped with a non-enriched injector. There will therefore be areas hotter than others upstream of the high-pressure turbine of the turbomachine.

According to another aspect, the assembly is configured so that the angular position of said ring relative to the air supply means is modified so as to increase the air passage section in said air supply means when the injector head is in the second position.

As shown, in the second position, the injector head is less recessed into the combustion chamber. The injector head thus benefits from a protective and cooling effect of the air flowing through the injection system, which limits coking and wear of the injector head due to high combustion chamber temperatures.

Furthermore, by increasing the air passage section in the air supply means, the air permeability of the injection system is increased. The fuel enrichment rate in the combustion chamber is thus reduced. The primary zone of the combustion chamber is therefore depleted of fuel, which makes it possible to reduce pollutant emissions.

At least for these reasons, the coupling of the second position of the injector head and the increase in the air passage sections in the air supply means proves advantageous when the turbomachine operates in a regime above a certain threshold, for example above ground idle. Such a coupling is particularly advantageous when the turbomachine operates in full throttle conditions, such as for example during the take-off phase.

According to another aspect, the air supply means comprise an annular row of air injection orifices regularly distributed on the bowl around said central axis.

Advantageously, the bowl is the last element of the injection system before the air enters the combustion chamber. Also, the air losses between the air flow passing through the air supply means and the air flow arriving in the combustion chamber are limited, which allows better control of the air flow entering the combustion chamber.

According to the invention, the air injection orifices may in particular be included in a truncated cone-shaped wall of the bowl.

According to another aspect, the injection system further comprises at least one auger, said air supply means comprising a plurality of air introduction orifices regularly distributed on said at least one auger around said central axis.

The at least one auger allows a rotating air flow to be obtained which is introduced into the combustion chamber.

According to another aspect, the assembly further comprises first shape-connecting means integral with the ring and cooperating with second shape-connecting means integral with the injector, the first and second shape-connecting means being configured to drive the ring in rotation about said central axis when the injector moves between the first and second positions.

The coupling between the rotation of the ring and the movement of the injector between the first position and the second position is therefore possible thanks to the first form connection means and the second form connection means. The form connection allows this coupling to be done mechanically, without the need to use energy-consuming and difficult-to-install electronic systems.

According to another aspect, the first shape-connecting means comprise a slot, the second shape-connecting means comprising a pin engaged in said slot. The first shape-connecting means and the second shape-connecting means are therefore simple to implement and their cooperation presents a low risk of failure. Furthermore, the pin being engaged in the slot, the cooperation between them can be direct, without any element interposed between the two. The manufacture of the assembly is thus facilitated and its bulk is limited.

According to another aspect, the slot is oblique with respect to said central axis.

According to the invention, the slot is included in a first plane. By oblique, it is meant that the slot forms a non-zero angle less than 90° with a projection of the central axis on said first plane comprising the slot.

Due to the oblique shape of the slot, the movement of the injector along the central axis causes the ring to rotate about the central axis, so as to be able to increase or reduce the air passage section in the air supply means. In particular, the oblique shape makes it possible to gradually rotate the ring about the central axis as the injector moves between the first position and the second position. The ring can thus adopt a plurality of different angular positions depending on the position of the injector along the central axis, which makes it possible to modify the air passage section in the air supply means. It is therefore possible to finely adjust the permeability of the injection system, which proves advantageous when the turbomachine operates at speeds involving intermediate powers between ground idle and full throttle speeds.

According to another aspect, the pin carries a roller capable of cooperating by rolling on internal faces of the slot, said internal faces being opposite each other.

The roller thus facilitates the sliding of the pin in the slot, which contributes to the proper functioning of the coupling between the rotation of the ring and the movement of the injector head along the central axis. The roller also limits the friction between the pin and the slot, which reduces the risk of wear of the pin and the slot. Advantageously, the roller is easily replaceable with a new roller in the event of deterioration.

Furthermore, the slot comprising internal faces which are opposite each other and with which the roller cooperates by rolling, the rotation of the ring about the central axis occurs both when the injector head passes from the first to the second position and in the opposite direction. In particular, when the injector head passes from the first to the second position, the ring rotates about the central axis in a first direction, and when the injector head passes from the second position to the first position, the ring rotates about the central axis in a second direction opposite to the first direction.

According to another aspect, the ring comprises a primary stop member arranged circumferentially between two static secondary stop members carried by the injection system, said secondary stop members being circumferentially spaced from each other.

In this text, “circumferential” or “angular” means in a direction following a trajectory around the central axis of the injection system, this trajectory preferably delimiting a circular section with an axis equal to the central axis.

The primary stop member of the ring and the two secondary stop members of the injection system ensure that the ring cannot move beyond a given angular distance defined by the circumferential dimension of the primary stop member of the ring and the spacing between two stop faces of the secondary stop members of the injection system. In particular, the ring cannot move beyond an angular distance equal to the difference between the spacing between the two stop faces of the secondary stop members and the circumferential dimension of the primary stop member.

According to another aspect, the slot comprises an open end through which the pin is engaged in said slot, the open end having a width greater than a circumferential distance separating said secondary stop members.

The width of the open end of the slot means the dimension of the opening of the slot that is substantially perpendicular to the central axis and to the direction in which the pin projects from the ring. In this case, the pin projects radially from the ring.

The circumferential distance between the secondary stop members is the spacing between the two stop faces of the secondary stop members measured in the circumferential direction. As indicated, the rotation of the ring is limited to an angular distance equal to the difference between the circumferential spacing between the two stop faces of the secondary stop members and the circumferential dimension of the primary stop member. Since the width of the open end of the slot is greater than the circumferential distance between the secondary stop members, it is ensured that the pin can be engaged in the slot regardless of the angular position of the ring relative to the rest of the injection system.

According to another aspect, the pin can be mounted so as to be movable on the ring substantially parallel to said central axis. The axial position of the pin on the ring can thus vary between a first position, called the upstream position, and a second position, called the downstream position. In the downstream position, the pin is further axially from the upstream end of the ring than in the upstream position. The upstream position facilitates the introduction of the pin into the slot. The downstream position makes it possible to decouple the movement along the central axis of the injector from the rotation of the ring. It is thus possible, for example, to ensure that the injection system has high or low air permeability whether the injector is in the first position or in the second position. Furthermore, the downstream position prevents the pin from being subjected to the forces exerted on it by the slot when the level of air permeability of the injection system is not decisive for the proper operation of the turbomachine. The risk of wear of the pin is thus reduced.

According to another aspect, there is provided a turbomachine, such as a turbojet or a turboprop, comprising at least one turbomachine assembly as described above.

Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the attached drawings, in which:

Fig. 1

shows a schematic axial sectional view of a portion of a turbomachine according to the present invention.

Fig. 2

shows a schematic view of a section of a portion of the combustion chamber illustrated in the , said part being delimited by dotted lines on the .

Fig. 3

shows a schematic perspective view from a first angle of an injection system and a fuel injector for a turbomachine according to an exemplary embodiment, the injection system comprising a ring and a mixing bowl.

Fig. 4

is a schematic view of the mixing bowl and the ring of the injection system of the according to a first exemplary embodiment of the ring, said view being taken from upstream of the mixing bowl, in a second angular position of the ring relative to the mixing bowl.

Fig. 5

is an enlarged view of an area of the ring of the in a second angular position of the ring relative to the mixing bowl.

Fig. 6

is an enlarged view of an area of the ring of the in a third angular position of the ring relative to the mixing bowl.

Fig. 7

is an enlarged view of an area of the ring of the in a first angular position of the ring relative to the mixing bowl.

Fig. 8

is a schematic view of the mixing bowl and the ring of the injection system of the according to a second exemplary embodiment of the ring, said view being taken from upstream of the mixing bowl when the ring is in a first angular position of the ring relative to the mixing bowl.

Fig. 9

is a schematic view of the mixing bowl and the ring of the injection system of the according to a third exemplary embodiment of the ring, said view being taken from upstream of the mixing bowl when the ring is in a first angular position of the ring relative to the mixing bowl.

Fig. 10

is a schematic view of the mixing bowl and the ring of the injection system of the according to a fourth exemplary embodiment of the ring, said view being taken from upstream of the mixing bowl when the ring is in a first angular position of the ring relative to the mixing bowl.

Fig. 11

is a schematic view of the mixing bowl and the ring of the when the ring is in a second angular position of the ring relative to the mixing bowl.

Fig. 12A

shows a schematic axial sectional view of a turbomachine assembly comprising a fuel injector, an injection system and a combustion chamber according to an exemplary embodiment, the fuel injector being in a first position.

Fig. 12B

shows a schematic axial sectional view of the turbomachine assembly of the , the fuel injector being in a second position.

Fig. 13A

shows a schematic axial sectional view of the turbomachine assembly of the , the fuel injector being in the first position, the assembly comprising a controllable displacement device according to a first exemplary embodiment

Fig. 13B

shows a schematic axial sectional view of the turbomachine assembly of the , the fuel injector being in the second position.

Fig. 14A

shows a schematic axial sectional view of the turbomachine assembly of the , the fuel injector being in the first position, the assembly comprising a controllable displacement device according to a second exemplary embodiment

Fig. 14B

shows a schematic axial sectional view of the turbomachine assembly of the , the fuel injector being in the second position.

Fig. 15A

shows a schematic axial sectional view of the turbomachine assembly of the , the fuel injector being in the first position, the assembly comprising a controllable displacement device according to a third exemplary embodiment

Fig. 15B

shows a schematic axial sectional view of the turbomachine assembly of the , the injector being in the second position.

Fig. 16

shows a schematic perspective view of a detail of the injection system and fuel injector of the , the injector being in the second position.

Fig. 17A

shows a schematic perspective view from another angle of the injection system and fuel injector for turbomachine of the , the injector being in the first position, and a ring of the injection system being in a first position.

Fig. 17B

shows a schematic perspective view of a detail of the fuel injector and injection system of the .

Fig. 18A

shows a schematic perspective view of the injection system and fuel injector for turbomachine of the , the injector being in the second position, and the injection system ring being in a second position.

Fig. 18B

shows a schematic perspective view of a detail of the fuel injector and injection system of the .

To facilitate understanding of the invention, an axial direction A is defined which extends along a central axis 70 of an injection system 23, or parallel to this central axis 70, and a radial direction R which is perpendicular to the axial direction. Also, in the present text, “axial” means any direction substantially parallel to the central axis 70, and “radial” extends from any direction substantially perpendicular to the central axis 70.

There shows an axial sectional view of part of a turbomachine. The turbomachine is for example a turbojet or a turboprop.

As visible in this figure, the turbomachine comprises an annular combustion chamber 10 having an axis of revolution 38.

In the remainder of the description, when the terms “internal” and “external” are used to describe the combustion chamber, these terms are defined with reference to the axis of revolution 38 of the combustion chamber. When the terms “internal” and “external” are used to describe the injection system 23, these terms are defined with reference to the central axis 70 of the injection system 23.

The combustion chamber 10 is housed inside a casing 28. The combustion chamber 10 is in particular arranged at the outlet of a centrifugal diffuser 12 mounted at the outlet of a high-pressure compressor (not shown). The combustion chamber 10 is followed by a high-pressure turbine 14 of which only the inlet distributor 16 is shown.

As it emerges from the , a space 29, called the external bypass space, exists between the radially external wall 20 of the chamber 18 and the casing 28. The external bypass space 29 receives bypass air from the combustion chamber 10. This bypass air corresponds to an air flow from the high-pressure compressor which flows outside the combustion chamber 10.

The combustion chamber 10 comprises a radially inner wall 18 and a radially outer wall 20. The radially inner wall 18 and the radially outer wall 20 are walls of revolution, for example frustoconical with a section reducing downstream. Any other shape of combustion chamber 10 is also possible. For example, the chamber 10 could alternatively be a double-head combustion chamber.

It should be noted that in this text, the terms “upstream” and “downstream” are to be interpreted with reference to a conventional direction of flow of the air flow drawn in by the turbomachine in service.

The radially inner wall 18 and the radially outer wall 20 are preferably coaxial and arranged one inside the other. Such a combustion chamber is said to be convergent. The radially inner 18 and outer 20 walls are connected at their upstream ends to an annular chamber bottom wall 22 and fixed downstream for example by inner 24 and outer 26 annular flanges.

As illustrated in the , the external annular flange 26 can bear radially externally on the casing 28. Furthermore, the external annular flange 26 can bear axially on a radial flange 30 for fixing the distributor 16 of the high-pressure turbine to the casing 28.

The internal annular flange 24 of the combustion chamber 10 is for example in radial and axial support on an internal annular part 32 for fixing the distributor 16 to an internal annular wall 34.

The outer wall 20 and the casing 28 each comprise at least one orifice for installing at least one spark plug 42 for the combustion chamber 10.

The external annular wall 20 of the combustion chamber may also comprise an annular row of primary orifices 44 for diluting an air/fuel mixture arranged upstream of the spark plug 42.

The chamber bottom 22 comprises openings 25, preferably regularly distributed around the axis of revolution 38. Each opening 25 is shaped to receive an injector head 40 of an injector 36 and a respective injection system 23. Each injector head 40 and each injection system 23 are in particular installed around a respective central axis 70.

As will be detailed, each injector 36 makes it possible to introduce fuel into the combustion chamber 10. An example of injector 36 will be described later with reference to FIGS. 12A to 18B.

Now an example of an injection system 23 received in one of the cavities 25 will be described, the injection systems 23 received in each of the other cavities 25 being similar or identical to that described below.

The injection system 23 includes a mixing bowl 50 (illustrated in the ) mounted in the respective opening 25 of the chamber bottom wall 22.

The mixing bowl 50 comprises a substantially truncated cone-shaped wall 56 with a central axis 70. The wall 56 is flared downstream and connected at its downstream end to a cylindrical rim 58 extending upstream and mounted axially in the opening 25 of the chamber bottom wall 22 with an annular deflector 60.

The truncated cone-shaped wall 56 of the bowl comprises a part 68 provided with an annular row of air injection orifices 64 regularly distributed around the axis 70 of the injection system 23.

The centers of the air injection orifices 64 are for example spaced from each other by the same distance. Generally, the air injection orifices 64 all have the same shape and the same surface. The air injection orifices 64 are for example circular.

The orifices 64 make it possible to introduce a flow of air from the high-pressure compressor inside the bowl 50, and therefore, inside the chamber 10.

Each injection system 23 may further comprise at least one turbulence swirler. In this case, the system 23 comprises a coaxial upstream swirler 46 and a coaxial downstream swirler 48. The swirlers 46, 48 are separated from each other by a radial wall 52.

The downstream auger 48 is fixed to the upstream end of the truncated cone wall 56 of the bowl 50 by an intermediate annular piece 62.

As it emerges from the , the auger 46 comprises a plurality of blades 47 extending radially around the axis of the auger 46 and regularly distributed around this axis. The auger 48, not visible in this figure, has a structure similar or identical to that of the auger 46. An air introduction orifice 49 is thus formed between two consecutive blades 47 of the same auger 46, 48, so as to form in each auger 46, 48 an annular row of air introduction orifices 49 around the central axis 70. An air flow from the high-pressure compressor flows through the row of air introduction orifices 49 of the augers 46, 48. An air flow therefore comes from each of the augers 46, 48, these air flows subsequently being received inside the bowl 50. In particular, the air flow from each auger 46, 48 is a rotating air flow.

A venturi 54 may be connected to a radially inner end of the radial wall 52, as seen in the example of the . The venturi 54 extends axially downstream within the downstream swirler 48 and separates the rotating air flows introduced via the orifices 49. A first annular air flow vein is formed within the venturi 54 and a second annular air flow vein is formed outside the venturi 54.

As indicated above, the air flows exiting the orifices 49 of the spirals 46, 48 and the orifices 64 of the bowl 50 are received inside the bowl 50. Also, the orifices 49, 64 form means for supplying air inside the bowl 50. The air supplied inside the bowl 50 is in particular used to produce a layer of air-fuel mixture with the fuel injected by the corresponding injector 36, as will be detailed later.

The injection system 23 further comprises a ring 72 arranged upstream of the mixing bowl 50 around the central axis 70. According to a non-limiting exemplary embodiment, the ring 72 is mounted around the tendrils 46, 48. The ring 72 may have a substantially cylindrical shape.

Advantageously, the ring 72 is mounted to be able to rotate about the central axis 70, in particular between a first angular position and a second angular position relative to the mixing bowl 50. Of course, the ring 72 can also adopt a plurality of angular positions between the first angular position and the second angular position relative to the mixing bowl 50. In the following, any angular position of the ring 72 between the first angular position and the second angular position will be called the third angular position.

The ring 72 may include openings 75, visible on the , distributed around the central axis 70. For example, the ring 72 may comprise a first annular row of openings 75 facing the upstream spiral 46 and a second annular row of openings 75 facing the downstream spiral 48. The openings 75 allow the passage of air through the orifices 49 of the spirals 46, 48.

The ring 72 may further be provided with a sealing collar 76 which extends upstream and against the portion 68 of the frustoconical wall. In particular, the sealing collar 76 may fit a portion of the frustoconical wall of the bowl 50. The sealing collar 76 comprises at least one opening arranged substantially opposite the portion 68 of the frustoconical wall. In the figures, the sealing collar 76 comprises several openings, referenced 78, 86, 88, 92, 94, 98 or 100, forming an annular row of openings which are distributed around the axis 70 of the injection system 23.

The openings 78, 86, 88, 92, 94, 98, 100 may have different shapes and/or different sections. Figures 4 and 8 to 11, showing a view of the bowl 50 and the ring 72 from upstream of the bowl 50, show different non-limiting examples of embodiments of the openings of the collar 76.

In a first embodiment illustrated by the , the number of openings 78 is equal to the number of air injection ports 64. The circular arc α1 delimited between the center of two adjacent air injection ports 64 is equal to the circular arc α2 delimited between the same side of two adjacent openings 78.

The openings 78 of the ring 72 have an oblong shape that extends along an arc of a circle A1 with a center C. The center C is positioned on the axis 70 of the injection system. The arc of a circle A1 extends over a length greater than the diameter of the air injection orifices 64. The arc of a circle A1 extends over a length greater than the dimension of the openings 78. In addition, the openings 78 have a dimension D that decreases circumferentially from a first end 79 to a second end 81, for example, in a clockwise direction. In particular, the dimension D is measured in a direction contained in the sealing collar 76 and perpendicular to the arc of a circle A1.

Thus, in the embodiment shown as an example in FIGS. 4 to 7, the dimension D at a left end of the opening 78 is substantially equal to the diameter d of the air injection ports 64. The dimension D is further equal to half the diameter d of the air injection ports 64 at a right end of the opening 78.

Advantageously, in the first angular position of the ring 72, each injection orifice 64 is opposite the right end of a respective opening 78, while in the second angular position of the ring 72, illustrated in the , each injection port 64 is opposite the left end of the respective opening 78. The closing collar 76 of the ring 72 is therefore configured to close at least a portion of each air injection port 64 when the ring 72 passes from the second angular position to the first angular position. In particular, an air passage section in the air injection ports 64 is halved when the ring 72 passes from the second angular position to the first angular position. The air flow rate passing through the openings 78 and the air injection ports 64 and entering the combustion chamber is therefore halved when the ring 72 passes from the second angular position to the first angular position.

The position of the opening 78 relative to the respective orifice 64 in the third angular position of the ring 72 is illustrated in the . It corresponds to a position in which the air passage section in the injection orifices 64 is intermediate to the air passage section in these orifices 64 in the first angular position of the ring 72 and to the air passage section in the orifices 64 in the second angular position of the ring 72. The air flow passing through the openings 78 and the air injection orifices 64 is therefore intermediate between the air flow obtained in the first angular position and the air flow obtained in the second angular position.

Also, by varying the angular position of the ring 72 relative to the mixing bowl 50, the air passage section in the orifices 64 can be increased or decreased. The air flow entering the combustion chamber 10 is therefore increased or decreased, in particular in a linear and progressive manner. This variation in the air flow entering the combustion chamber 10 has been materialized by points in FIGS. 5 to 7.

Alternatively, the dimensions D at the right end or left end of the openings 78 may have a different dimension to reduce or increase the air flow rates passing through the openings 78 and the air injection ports 64.

Alternatively, the dimension D is constant circumferentially over one angular portion and then decreases circumferentially over another angular portion.

Alternatively, the openings 78 may for example have a substantially triangular or parallelepipedal shape which extends along an arc of a circle.

There schematically represents a view of the mixing bowl 50 and the ring 72 according to a second exemplary embodiment.

In this case, the sealing collar 76 of the ring 72 is provided with several openings 86, 88 forming an annular row of openings which are regularly distributed around a center C of the axis 70 of the fuel injection system.

The ring 72 has twice as many openings 86, 88 as there are air injection ports 64 of the mixing bowl. The arc of a circle α3 delimited between the centers of two adjacent air injection ports 64 is equal to twice the arc of a circle α1 delimited between the centers of two adjacent openings 86, 88.

The annular row of openings of the ring 72 further comprises two first circular sectors B1 and two second circular sectors B2. Each first circular sector B1 is arranged between two second circular sectors B2. The two second circular sectors B2 are arranged opposite each other relative to the center C.

The first circular sectors B1 comprise only first openings 86. The second circular sectors B2 comprise first openings 86 and second openings 88.

The first openings 86 are circular and have a diameter and surface area identical to the surface area of the air injection ports 64 of the mixing bowl. On the , the air injection ports 64 have been shown in dotted lines with a diameter greater than the diameter of the first openings 86 to facilitate understanding of this embodiment.

The second openings 88 are arranged circumferentially between two first openings 86.

The second openings 88 are circular and have a smaller surface area, preferably at least 30% smaller, than the surface area of the first openings 86.

Alternatively, the second openings 88 have a surface area at least 45% less than the surface area of the first openings 86.

Alternatively, the second openings 88 have a surface area at least 60% less than the surface area of the first openings 86.

The second circular sectors B2 are positioned on the side of the internal 18 and external 20 truncated cone-shaped revolution walls of the combustion chamber. This configuration makes it possible to reduce the air injected at the angular flame propagation positions without impacting the non-propagation positions and therefore without having too much impact on efficiency and pollutant emissions.

In this second exemplary embodiment, when the ring 72 is in the first angular position, illustrated in the , the second openings 88 are positioned facing the air injection orifices 64 in each second circular sector B2, and the first openings 86 are positioned facing the air injection orifices 64 in each first circular sector B1. Thus, advantageously, the first angular position makes it possible to reduce the air passage section in the air injection orifices 64 placed facing each second angular sector B2, while keeping constant the air passage section in the orifices 64 placed facing each first angular sector B1. The air flow rate passing through the openings 86 and the air injection orifices 64 in the first angular sectors B1 is therefore greater than the air flow rate passing through the openings 88 and the orifices 64 in the second angular sectors B2 in the first angular position of the ring 72.

In the second angular position (not shown) of this second exemplary embodiment, the angular position of the ring 72 relative to the mixing bowl 50 is modified by an angle corresponding to the arc of a circle α1. In each second circular sector B2, the first openings 86 are then positioned opposite the air injection ports 64 and in each first circular sector B1, the first openings 86 remain positioned opposite the air injection ports 64.

The second angular position makes it possible to obtain an air passage section in the injection orifices 64 that is equal in all the angular sectors B1 and B2 of the ring 72. The air flow rate passing through the openings 86, 88 and the air injection orifices 64 is therefore uniform and equal in the first circular sectors B1 and in the second circular sectors B2.

In this second exemplary embodiment, in the first angular position of the ring 72, the closing collar 76 is therefore configured to close a part of certain orifices 64 opposite each second angular sector B2.

There schematically represents a view of the mixing bowl 50 and the ring 72 according to a third exemplary embodiment.

The sealing collar 76 of the ring 72 is provided with several openings 92, 94 forming an annular row of openings which are regularly distributed around the axis 70 of the fuel injection system.

In this third embodiment, the annular row of openings has twice as many openings 92, 94 as there are air injection orifices 64 of the mixing bowl. The circular arc α1 delimited between the centers of two adjacent air injection orifices 64 is equal to twice the circular arc α4 delimited between the center of a first opening 92 and the center of a second adjacent opening 94.

In particular, the annular row of openings 92, 94 of the ring 72 comprises first openings 92 and second openings 94. Each second opening 94 is arranged circumferentially between two first openings 92.

The first openings 92 have a diameter substantially equal to the diameter d of the air injection orifices 64 of the mixing bowl.

The second openings 94 have a smaller surface area, preferably 30% smaller, than the surface area of the first openings 92.

Alternatively, the second openings 94 have a surface area at least 45% less than the surface area of the first openings 92.

Alternatively, the second openings 94 have a surface area at least 60% less than the surface area of the first openings 92.

In this third embodiment, in the first angular position of the ring 72, illustrated in the , the second openings 94 are arranged opposite the air injection ports 64, the first openings 92 being arranged opposite a part 68 of the frustoconical wall which closes them.

In the second angular position of the ring 72 (not illustrated), the first openings 92 are arranged opposite the air injection orifices 64, the second openings 94 being arranged opposite a part 68 of the frustoconical wall which closes them.

In this third exemplary embodiment, the sealing collar 76 of the ring 72 is therefore configured to seal a portion of each air injection orifice 64 when it is positioned in the first angular position. Consequently, in the first angular position of the ring 72 according to this third exemplary embodiment, the air passage section in the orifices 64 is less than the air passage section in these orifices 64 when the ring 72 is in its second angular position.

It is noted that in the third embodiment described above, to move from the first angular position to the second angular position of the ring 72, and vice versa, the angular position of the ring 72 relative to the mixing bowl 50 is modified by an angle corresponding to the arc of a circle α4.

Figures 10 and 11 schematically represent a view of the mixing bowl 50 and the ring 72 according to a fourth exemplary embodiment, in a first angular position ( ) and in a second angular position ( ) of ring 72.

In this fourth embodiment, the ring 72 comprises an annular row of openings comprising first openings 98 and two second openings 100. Along the row, two second openings 100 are circumferentially adjacent to each other and two second openings 100 are arranged between two first openings 98.

The total number of first 98 and second 100 openings is greater than the number of ports in the row of air injection ports of the mixing bowl. The circular arc α1 delimited between the centers of two adjacent air injection ports 64 is equal to the circular arc α5 delimited between the centers of two second openings 100. The circular arc α6 delimited between the centers of two first openings 98 is equal to twice the circular arc α1.

The first openings 98 and the second openings 100 are circular.

The first openings 98 have a diameter equal to the diameter of the air injection ports 64. The second openings 100 have a diameter and a surface area smaller than the diameter and the surface area of the first openings 98. For example, the second openings 100 have a diameter and a surface area at least 30% smaller than the diameter and the surface area of the first openings 98. Alternatively, the second openings 100 have a diameter and a surface area at least 45% smaller than the diameter and the surface area of the first openings 98. Alternatively, the second openings 100 have a diameter and a surface area at least 60% smaller than the diameter and the surface area of the first openings 98.

Preferably, the first openings 98 have a surface area twice the surface area of the second openings 100.

In this fourth embodiment, the second openings 100 are opposite the air injection orifices 64 in the first angular position of the ring 72, as is apparent from the .

In the second angular position of the ring 72 according to the fourth embodiment, illustrated in the , one orifice 64 out of two is opposite one of the first openings 98, the other orifice 64 being closed by the ring 72. In this second angular position, the second openings 100 are opposite a solid part 68 of the truncated cone wall.

Also, in the fourth embodiment of the ring 72, the air passage section in the orifices 64 in the first angular position of the ring 72 is less than the air passage section of the unobstructed orifices 64 in the second angular position. Also, in the first angular position, n air flows having a low air flow rate enter the combustion chamber 10, while in the second angular position, m air flows carrying with a higher air flow rate enter the combustion chamber, with n and m positive natural integers.

The number m of air flows is less than the number n of air flows. In particular, the number m is twice less than the number n.

When the first openings 98 have a surface area 30% less than the surface area of the second openings 100, the flow rate of the air flows and their number varies between the first angular position of the ring 72 and the second angular position of the ring 72, but the total flow rate of all the air flows entering the chamber through the air injection orifices 64 remains constant.

The ring 72 may furthermore be shaped to increase or reduce an air passage section of the openings 75 fluidly connecting with the tendrils 46, 48, and/or to increase or reduce an air passage section of the orifices 49 of the tendrils 46, 48. According to a non-illustrated and non-limiting example, the ring 72 may comprise one or more closure collar(s) arranged substantially axially opposite at least one of the tendrils 46, 48. Each closure collar may, in a manner similar to the closure collar 76 described above, comprise several openings forming an annular row of openings which are distributed around the axis 70 of the injection system 23 and which make it possible to reduce or increase an air passage section in the openings 49 by rotating the ring between the first angular position and the second angular position.

Consequently, the rotational drive of the ring 72 around the central axis 70 makes it possible to reduce or increase by rotation the air passage section in the air supply means inside the bowl 50. It is thus possible to regulate the air flow entering the combustion chamber 10 and to modify the position and/or the number and/or the shape of the air flows entering the combustion chamber 10 by simple rotation of the ring 72 around the central axis 70.

As visible in the figures, the ring 72 further comprises a pin 84. The pin 84 extends for example radially towards the outside of the ring 72. According to a non-limiting example, the pin has a substantially cylindrical shape comprising a lateral surface 84-1.

Preferably, the pin 84 is located at an upstream end portion of the ring 72. In certain cases, the pin 84 can be mounted mobile in translation on the ring 72. The pin 84 can thus be moved on the ring 72 in a first direction moving away from the upstream end of the ring 72 and in a second direction moving closer to the upstream end of the ring 72.

As visible on the , the pin 84 can carry a roller 83. The roller 83 can have a substantially annular shape. The roller 83 can thus surround the lateral surface 84-1 of the pin 84. The roller 83 is advantageously movable in rotation around the lateral surface of the pin 84.

As will be detailed with reference to FIGS. 16 to 18A, the pin 84 constitutes a form connection means cooperating with other form connection means to drive the ring 72 in rotation around the central axis 70.

As it emerges from the , the upstream end of the ring 72 may comprise a primary stop member 87. In this figure, the primary stop member 87 extends substantially radially towards the inside of the ring 72, without this being limiting.

The primary stop member 87 is arranged circumferentially between two secondary stop members 87-1.

The secondary thrust members 87-1 are carried for example by the injection system 23, in particular by a part of the injection system 32 which does not move when the turbomachine is in operation. Thus, the secondary thrust members 87-1 are static. In the non-limiting example of the , the secondary stop members are carried by an upstream end of the upstream auger 46 and project therefrom substantially parallel to the central axis 70.

Each of the secondary stop members 87-1 comprises a stop face corresponding to the face of the respective secondary stop member 87-1 which is circumferentially opposite the primary stop member 87.

The secondary stop members 87-1 are separated from each other by a circumferential distance D1 which corresponds to the circumferential distance between the stop face of each secondary stop member 87-1. Advantageously, the circumferential distance D1 is greater than a circumferential dimension L1 of the primary stop member 87. Also, the ring 72 can be driven in rotation about the central axis 70 but in a limited manner. In particular, the ring 72 can be driven in rotation about the central axis 70 until the primary stop member 87 comes into abutment against one of the stop faces of the secondary stop members 87-1. The maximum angular distance that the ring 72 can travel around the central axis 70 is therefore equal to the difference between the circumferential distance D1 separating the two stop faces of the secondary stop members 87-1 and the circumferential dimension L1 of the primary stop member 87.

It is noted that advantageously, the maximum angular distance that the ring 72 can travel around the central axis 70 before the primary stop member 87 collides with one of the secondary stop members is greater than the angular distance that the ring 72 travels to pass from the first angular position to the second angular position.

Now one of the fuel injectors 36 will be described with particular reference to FIGS. 12A to 15B.

The fuel injector 36 comprises a mast 39 and an injector head 40. The mast 39 and the injector head 40 advantageously have substantially tubular shapes.

The mat 39 extends from the injector head 40 to the casing 28, for example substantially perpendicular to the central axis 70. Preferably, the mat 39 extends in the radial direction.

The mast 39 comprises a radially outer end portion 39-1 and a radially inner end portion 39-2.

The radially external end portion 39-1 of the mast 39 may be arranged outside the casing 28, as clearly visible in FIGS. 12A to 15B. For this purpose, the casing 28 may comprise an opening 43 for the passage of the injector 36. Advantageously, as is apparent from the figures, the opening 43 has an axial dimension greater than an axial dimension of the mast 39 of the injector 36. The injector 36 can thus be moved substantially parallel to the central axis 70 in the opening 43, as will be detailed.

The injector head 40 extends along the central axis 70 from the radially inner end portion 39-2 of the mast 39. As will be detailed, the head 40 is advantageously movable between a first position and a second position along the central axis 70.

The head 40 is at least partially introduced into the opening 25 of the bottom wall 22. In particular, the head 40 is at least partially installed in a substantially cylindrical cavity defined by the injection system 23. A downstream end of the injector head 40 comprises for example a nozzle (not illustrated) making it possible to inject fuel into the combustion chamber 10 along a fuel injection axis. Advantageously, the fuel injection axis is coincident with the central axis 70.

As already indicated, the fuel injected into the chamber 10 is mixed with the air introduced into the chamber 10 by the injection system 23, which makes it possible to produce a layer of air-fuel mixture having a substantially truncated cone shape widening downstream. The air-fuel mixture is ignited by the spark plug 42 during the ignition or re-ignition phases of the turbomachine. The flame created is maintained by the continuous supply of air-fuel mixture during the other operating phases of the turbomachine during which the spark plug 42 is extinguished.

The injector 36 can be carried by a plate 45 mounted on the casing 28. In particular, the radially external end portion 39-1 of the mast 39 can be connected to the plate 45.

The plate 45 is mounted on the housing 28 so as to cover the opening 43. Preferably, the plate 45 has dimensions allowing it to completely cover the opening 43 of the housing 29.

As will be detailed, the plate 45 can be slidably mounted on the casing 28, in particular on a radially external surface 28-1 of the casing 28. Advantageously, the dimensions of the plate 45 make it possible, whatever the position of the plate 45 on the casing 28, to cover the opening 43, preferably in its entirety.

The plate 45 makes it possible to hold the injector 36 radially in position relative to the casing 28.

Advantageously, the plate 45 is mounted in a sealed manner on the opening 43. For this purpose, a sealing member 51 is provided. As visible in FIGS. 2A and 2B, the sealing member 51 may be arranged around the plate 45. For this purpose, the sealing member 51 may have a substantially annular shape, an internal surface of which is substantially complementary to a contour of the plate 45. The sealing member may thus be in contact with the entire contour of the plate 45.

According to another example not illustrated, the sealing member 51 could be arranged radially between the plate 45 and the radially external surface 28-1 of the casing 28. In such cases, the sealing member 51 can also have a substantially annular shape shaped so as not to block the opening 43.

Thanks to the sealing member 51, the risk of unwanted infiltration of fluids through the casing 28 is reduced.

According to a non-limiting example, the sealing member 51 may be a bellows system, also called an accordion seal. The accordion seal has the advantage of being able to be stretched and compressed without the seal being lost. This is advantageous when, as indicated above, the plate 45 is slidably mounted on the housing 28. For example, when the sealing member 51 is arranged around the plate 45, the accordion seal is able to stretch and compress to remain in contact with the entire contour of the plate 45 when the latter slides, thus preventing the seal from being lost.

The injector 36 is connected, for example at its radially external end, to a fuel circuit comprising a fuel rail 53. The fuel rail 53 is mounted outside the casing 28. According to a non-limiting exemplary embodiment, the fuel rail 53 is mounted on the plate 45, as illustrated in the figures.

The fuel rail 53 is fluidically connected to the injector 36. A hollow conduit 55, also called a lyre in the following, is arranged between the fuel rail 53 and the injector 36. The fuel from the rail 53 can thus flow from the rail 53 to the injector via the lyre 55, to then be injected into the chamber 10 through the injector head 40.

Advantageously, the lyre 55 is made of a rigid material, which allows the ramp 53 and the injector 36 to move together, as will be detailed. Alternatively, the lyre 55 can be made of an elastically deformable material allowing any movements of the injector 36 to be decoupled from those of the ramp 53.

As previously indicated, the injector head 40 is movable between a first position and a second position. For this purpose, at least one controllable displacement device 57, illustrated in FIGS. 13A to 15B, is provided for each injector 36.

The controllable displacement device 57 is for example configured to drive the injector head 40 in translation along the central axis 70 in solidarity with a movement of the fuel rail 53. To this end, as illustrated in the non-limiting examples of FIGS. 13A to 15B, the controllable displacement device 57 can be connected to the plate 45. The device 57 is then configured to control the sliding of the plate 45 on the radially external surface 28-1 of the casing 28. In particular, the controllable displacement device 57 can drive the plate 45 in movement in a direction substantially parallel to the central axis 70. As indicated previously, the plate 45 can carry both the injector 36 and the rail 53. Consequently, in such cases, the movement of the plate 45 causes a movement in solidarity of the rail 53 and the injector 36. The injector head 40 36 is thus moved along the central axis 70 between a first position and a second position.

Alternatively, the controllable displacement device 57 could be connected directly to the ramp 53 or to the injector 36 to drive them integrally in translation parallel to the central axis 70 and thus cause the displacement of the head 40 between the first position and the second position.

In other cases, the controllable displacement device 57 is configured to drive the injector head 40 in translation along the central axis 70 without moving the fuel rail 53. Such cases occur for example when the controllable displacement device 57 is connected to the plate 45 or to the injector 36, the fuel rail 53 is not carried by the plate 45 and the movements of the injector 36 are decoupled from the movements of the fuel rail 53.

In the figures, the first position of the head 40 is illustrated by FIGS. 12A, 13A, 14A and 15A, while the second position of the head 40 is illustrated by FIGS. 12B, 13B, 14B and 15B. As can be seen from these figures, in the first position the head 40 is further recessed into the combustion chamber 10 than in the second position. Thus, when the head 40 moves from the second position to the first position, it is moved along the central axis 70 in a first direction towards an outlet plane of the injection system 23 in the combustion chamber 10. Conversely, when the head 40 moves from the first position to the second position, the head 40 moves in a second direction opposite to the first direction. It is noted that the outlet plane of the injection system 23 also corresponds to an outlet plane of the bowl 50.

As indicated above, the sinking of the injector head 40 into the combustion chamber 10 makes it possible to increase the re-ignition ceiling of the turbomachine and to improve the atomization of the fuel to reduce pollutant emissions. Also, the first position is advantageous during the ignition, re-ignition or ground idling phases of the turbomachine. The second position makes it possible to cool the head 40 thanks to the air introduced via the injection system 23, which limits the risks of coking and extends the useful life of the injector 36. The second position of the injector head 40 is therefore advantageous beyond the ground idling phase of the turbomachine.

Three non-limiting examples of embodiments of the controllable displacement device 57 will now be described with reference to FIGS. 13A to 15B.

In the example of Figures 13A and 13B, the controllable displacement device 57 comprises an electric motor 57-1 capable of being actuated by an external control. This external control triggers the displacement of the injector head 40 between the first position and the second position.

More precisely, the external command can cause the plate 45 to slide on the radially external surface 28-1 of the casing 28, which induces, as indicated previously, the integral movement of the injector 36 and, possibly, of the fuel rail 53 substantially parallel to the central axis 70. The head 40 is thus pushed further in or moved away from the inside of the combustion chamber 10.

The external command that actuates the engine 57-1 may be a signal sent by one or more sensors, not shown, making it possible to measure a parameter of the turbomachine, for example the fuel pressure in the fuel rail 53 or the bypass air pressure inside the casing 28. Such parameters are representative of the operating speed of the turbomachine. In particular, during the ignition, re-ignition or ground idling phases, the fuel pressure in the rail 53 and the bypass air pressure in the casing 28 are low, while beyond ground idling the pressure in the rail 53 and the bypass air pressure in the casing 28 increase significantly. Also, depending on the fuel pressure value in the rail 53 or the bypass air pressure in the casing 28, the operating speed of the turbomachine can be identified. The signal sent by the sensor(s) is thus adapted to control the movement of the head 40 of the injector 36 in the position most favorable to the operating speed of the turbomachine detected. As indicated previously, the first position of the head 40 proves advantageous in ignition, re-ignition and ground idle speed, while the second position of the head 40 is more suitable beyond ground idle.

The external command that actuates the engine 57-1 may also be a command sent by the actuation of a human-machine interface, such as a button, by a user of the aircraft. In such a case, the movement between the first and second positions of the head 40 is controlled manually, which also makes it possible to modify the axial position of the head 40 independently of the operating speed of the turbomachine, the fuel pressure conditions or the air pressure conditions inside the casing 28.

As illustrated in the figures, the motor 57-1 may be connected to an arm 57-2 connected to the plate 45, without this being limiting. The arm 57-2 may be an articulated arm capable of folding and unfolding to cause the plate 45 to slide on the casing 28, and thus drive the injector 36 and its head 40 in displacement in the axial direction. The arm 57-2 may also be a rigid arm configured to move substantially parallel to the central axis 70, thus causing a solid displacement of the plate 45 and therefore of the head 40 of the injector 36.

In the examples of Figures 14A to 15B, the controllable displacement device 57 comprises a cylinder 57-3 and a return member 57-4.

The cylinder 57-3 comprises a first cavity 157-1 and a second cavity 157-2 separated by a piston 157-3. The piston 157-3 is mounted axially movable in the cavities 157-1, 157-2 of the cylinder 57-3, so as to be able to modify the size of each of the cavities 157-1, 157-2. As will be detailed, the axial movement of the piston 157-3 in the cylinder 57-3 causes the displacement of the injector head 40 between the first position and the second position. For this purpose, the piston can be connected to the plate 45. The plate 45 is thus moved integrally with the piston 157-3 when the latter moves axially in the cylinder 57-3, causing both the displacement of the head 40 between the first and second positions. Alternatively, the piston 157-3 is connected to the injector 36 or to the fuel rail 53, thereby causing the injector 36 and/or the fuel rail 53 to move in lockstep with the movement of the piston 157-3, and therefore, the head 40 to move between the first and second positions.

The return member 57-4 is configured to deform elastically. The return member 57-4 is for example a spring.

In the figures, the spring 57-4 is in particular a spring working in compression during the movement of the head 40 between the first position and the second position. By “working in compression” is meant that during the movements between the first position and the second position of the head 40, the spring 57-4 passes from a rest position to a working position in which it is axially compressed relative to the rest position. The rest position of the spring 57-4 is in particular characterized by the fact of being a position in which the absolute value of the elastic potential energy of the spring 57-4 is zero, or at least less, than the absolute value of the elastic potential energy of the spring 57-4 in the working position.

Advantageously, in the first position of the head 40, visible in FIGS. 14A and 15A, the spring 57-4 is in the rest position, while in the second position of the head 40, visible in FIGS. 14B and 15B, the spring 57-4 is in the working position. Also, the head 40 of the injector 36 is in the first position as long as no sufficient force is exerted on the spring 57-4 to move it from the rest position to the working position. Similarly, this allows the head 40 to return to the first position as soon as the force for maintaining the spring 57-4 in the working position ceases. The spring 57-4 is therefore in particular a member for returning the head 40 to the first position.

The spring may be arranged in one of the first cavity 157-1 and the second cavity 157-2 of the cylinder. In particular, a first end of the spring 57-4 bears against the piston 157-3, while a second end of the spring 57-4 axially opposite its first end bears against a wall of the respective cavity 157-1 or 157-2 axially opposite the piston 157-3.

One of the cavities 157-1, 157-2 of the cylinder 57-3 is fluidically connected to means 67 for supplying pressurized fluid. For example, the cavity 157-1, 157-2 which does not house the spring 57-4 is fluidically connected to the means 67 for supplying pressurized fluid. The means 67 for supplying pressurized fluid allow the introduction of a pressurized fluid into the cavity 157-1 or 157-2 to which they are connected.

In FIGS. 14A to 15B, the spring 57-4 is housed in the first cavity 157-1 while the pressurized fluid supply means 67 are fluidically connected to the second cavity 157-2. Also, the spring 57-4 exerts a first force on a first face of the piston opposite a second face of said piston on which the pressurized fluid passing through the supply means 67 exerts a second force. Depending on a differential of the forces exerted on the two faces of the piston 57-4, the piston 157-3 moves in the cavities 157-1 and 157-2, thus causing the head 40 of the injector 36 to move between the first position and the second position. When the piston 157-3 moves inside the cylinder 57-3, the spring 57-4 is moved into the rest position or into the working position. In particular, when the force exerted by the pressurized fluid on the second face of the piston 157-3 is less than the force exerted by the spring 57-4 on the first face of the piston 157-3, the spring 57-4 is in the rest position, which causes the head 40 to be in the first position. Conversely, when the force exerted by the pressurized fluid on the second face of the piston 157-3 is greater than the force exerted by the spring 57-4 on the first face of the piston 157-3, the spring 57-4 is in the working position, which causes the head 40 to be in the second position.

In the example of FIGS. 14A and 14B, the pressurized fluid supply means comprise at least one orifice 61 formed through the casing 28 so as to supply the second cavity 157-2 with bypass air from the combustion chamber. The amount of bypass air entering the second cavity 157-2 depends on the bypass pressure in the external bypass space 29. In particular, the higher the bypass pressure in the external bypass space 29, the greater the amount of bypass air accessing the second cavity 157-2.

As previously indicated, when the combustion chamber 10 is off or operating in an ignition, re-ignition or ground idle phase of the turbomachine, the bypass pressure is low. Also, the quantity of bypass air introduced into the second cavity 157-2 of the cylinder 57-3 is low. The force exerted on the piston 157-3 by the bypass air is therefore less than the force exerted by the spring 57-4 on the piston. The head 40 is then in the first position, advantageous for the ignition, re-ignition or ground idle phases of the turbomachine, as already explained.

Conversely, when the combustion chamber 10 is ignited and the turbomachine exceeds a certain speed, for example ground idle, the bypass pressure is high. Also, the quantity of bypass air introduced into the second cavity 157-2 of the cylinder 57-3 is high, so that the force exerted on the piston 157-3 by the bypass air is greater than the force exerted by the spring 57-4. The head 40 is then moved to the second position, advantageous for the phases of the turbomachine beyond ground idle, as already explained.

In the example of figures 15A and 15B, the means 67 for supplying pressurized fluid comprise a connection pipe 67-2 from the second cavity 157-2 to the fuel circuit, in particular to the rail 53.

The second cavity 157-2 of the cylinder is thus filled with fuel depending on the fuel pressure in the fuel circuit. In particular, the quantity of fuel entering the second cavity 157-2 depends on the fuel pressure in the rail 53. The higher the fuel pressure in the rail 53, the greater the quantity of fuel accessing the second cavity 157-2.

As previously indicated, when the combustion chamber 10 is off or operating in an ignition, re-ignition or ground idling phase of the turbomachine, the fuel pressure is low. Also, the quantity of fuel introduced into the second cavity 157-2 of the cylinder 57-3 is low. The force exerted on the piston 157-3 by the fuel is therefore less than the force exerted by the spring 57-4 on the piston. The head 40 is then in the first position, advantageous for the ignition, re-ignition or ground idling phases of the turbomachine, as already explained.

Conversely, when the combustion chamber 10 is ignited and the turbomachine exceeds a certain speed, for example ground idle, the fuel pressure in the ramp 53 is high. Also, the quantity of fuel introduced into the second cavity 157-2 of the cylinder 57-3 is high, so that the force exerted on the piston 157-3 by the fuel is greater than the force exerted by the spring 57-4. The head 40 is then moved to the second position, advantageous for the phases of the turbomachine beyond ground idle, as already explained.

The exemplary embodiment of Figures 15A and 15B has the advantage of increasing the impermeability of the casing 28 compared to the example of Figures 14A and 14B, in which at least one orifice 61 formed through the casing 28 is provided.

It is noted that, according to a variant embodiment not illustrated, the same plate 45 can be connected to several controllable movement devices 57. For example, the same plate 45 can be connected both to a controllable movement device 57 according to the example of FIGS. 13A and 13B, and to a controllable movement device 57 according to one of the examples of FIGS. 14A to 15B.

Furthermore, the spring 57-4 could be a spring working in tension during the movement of the head 40 between the first position and the second position. By “working in tension” is meant that during the movements between the first position and the second position of the head 40, the spring 57-4 passes from a rest position to a working position in which it is stretched axially relative to the rest position. As indicated previously, the rest position of the spring 57-4 is notably characterized by the fact of being a position in which the absolute value of the elastic potential energy of the spring 57-4 is zero, or at least less, than the absolute value of the elastic potential energy of the spring 57-4 in the working position. As in the examples of FIGS. 14A to 15B, the spring 57-4 working in tension is advantageously in the rest position when the head 40 is in the first position, and in the working position when the head 40 is in the second position.

It is also noted that, according to a variant, the injector head 40 can also adopt one or more intermediate position(s) axially between the first position and the second position described above. As will be detailed, such an intermediate position can be advantageous when the turbomachine operates at a speed beyond ground idle but with a power lower than full throttle conditions.

As is clear from Figures 16 to 18B, the injector 36 may further comprise at least one plate 110. The plate 110 is notably carried by the mast 39. The plate 110 may for example be welded to the mast 39.

The plate 110 extends substantially perpendicular to the mast 39 of the injector 36. Advantageously, the plate 110 is arranged on the mast 39 at a radial position which prevents the plate 110 from being arranged axially opposite the injection system 23. Also, when the injector 36 is moved between the first position and the second position described above, the plate 110 does not collide with the injection system 23. The plate 110 may for example be placed at a radial position in which a millimeter clearance exists between the radially external surface of the ring 72 and the plate 110. Such a millimeter clearance may for example be between 1 mm and 10 mm, preferably between 1 mm and 5 mm. The injector 36 can thus move between the first position and the second position without there being any friction between the plate and the injection system 23, while ensuring that the space requirement is small.

As clearly visible on the , the plate 110 comprises a slot 115. The slot 115 extends substantially perpendicular to the mast 39.

The slot 115 includes an open end 115-1, a closed end 115-2, a first internal face 115-3 and a second internal face 115-4.

The first internal face 115-3 and the second internal face 115-4 extend substantially opposite each other between the open end 115-1 and the closed end 115-2.

In the non-limiting example of the figures, the first internal face 115-3 comprises a single continuous surface. Advantageously, the single surface of the first internal face 115-3 extends between the open end 115-1 and the closed end 115-2 so as to form a non-zero angle but less than 90°, with a projection in the radial direction of the central axis 70 on the plate 110. The first internal face 115-3 is therefore oblique relative to the central axis 70.

The second inner face 115-4 may include a first surface 115-41 and a second surface 115-42. The first surface 115-41 extends in the axial direction, from upstream to downstream, between the closed end 115-2 and the second surface 115-42. The second surface 115-42 extends in the axial direction, from upstream to downstream, between the first surface 115-41 and the open end 115-1.

The first surface 115-41 of the second internal face 115-4 extends substantially parallel to the only surface of the first internal face 115-3. Also, the first surface 115-41 of the second internal face 115-4 forms a non-zero angle, but less than 90°, with the radial projection of the central axis 70 on the plate 110. Preferably, the first surface 115-41 forms the same angle with the projection of the central axis 70 as the only surface of the first internal face 115-3. The first surface 115-41 is therefore also oblique with respect to the central axis 70. The slot 115 is therefore oblique, at least between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4.

The second surface 115-42 of the second internal face 115-4 is a face that diverges from the first surface 115-41. By “diverges” is meant that the second surface 115-42 forms with the first surface 115-41 an angle greater than 180°. Preferably, the first surface 115-41 and the second surface 115-42 of the second internal face 115-4 form between them an angle strictly greater than 180° and strictly less than 270°.

The closed end 115-2 includes a concave curved face 115-21. The concave curved face 115-21 connects the first internal face 115-3 to the second internal face 115-4, in particular to the first surface 115-41 thereof.

The open end 115-1 of the slot extends in the direction substantially perpendicular to the radial direction and to the radial direction between a free end of the first inner face 115-3 and a free end of the second surface 115-42 of the second inner face 115-4. The second surface 115-42 being divergent with respect to the first surface 115-41, the width L2 of the open end 115-1 of the slot is greater than the width L3 of the slot between the first inner face 115-3 and the first surface 115-41 of the second inner face 115-4. The width of the different parts of the slot 115 is understood to be the dimension of the slot 115 measured in the direction substantially perpendicular to the axial and radial directions.

As will be detailed, advantageously the width L2 of the open end 115-1 of the slot 115 is greater than the circumferential distance D1 separating the two stop faces of the secondary stop members 87-1.

As can be seen in particular from FIGS. 16, 17B and 18B, the pin 84 is engaged in the slot 115. The slot 115 forms in particular another means of shape connection cooperating with the pin 84 to drive the ring 72 in rotation about the central axis 70. As explained previously, the rotation of the ring 72 about the central axis 70 is a rotation of the ring 72 relative to the bowl 50.

As will be detailed, the shape cooperation between the slot 115 and the pin 84 makes it possible to move the ring 72 in rotation between the first angular position and the second angular position when the injector head 40 is moved between the first position and the second position described above.

The cooperation of the slot 115 and the pin 84 is now detailed with reference to figures 17A to 18B. In these figures, the visible ring 72 corresponds to that according to the exemplary embodiment of the , but of course any other 72 ring could be used.

In Figures 17A and 17B, the injector head 40 is in the first position, that is, moved toward the outlet plane of the bowl 50. The pin 84 is then engaged in the portion of the slot 115 between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4, near or in contact with the concave curved face 115-21 of the closed end of the slot 115, as illustrated in the .

In Figures 18A and 18B, the injector head 40 is in the second position, i.e., away from the outlet plane of the bowl 50 relative to the first position. As seen in the , the pin 84 is also engaged in the part of the slot 115 between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4, but it is further away from the concave curved face 115-21 than when the injector head 40 is in the first position.

Also, when the injector 36 moves from the first position to the second position, the plate 110 moves upstream, such that the slot 115 moves relative to the pin 84 in a direction moving the pin 84 away from the closed end 115-2 of the slot. Conversely, when the injector 36 moves from the second position to the first position, the plate 110 moves downstream, such that the slot 115 moves relative to the pin 84 in a direction moving the pin 84 closer to the closed end 115-2 of the slot 115.

Preferably, the width L3 of the slot between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4 is such that the lateral surface of the pin 84, or possibly the roller 83 which surrounds it, is in contact with the first internal face 115-3 and the first surface 115-41 during the entire movement of the slot 115 relative to the pin 84. When the roller 83 is provided, it cooperates by rolling on the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4. This facilitates the sliding of the pin 84 in the slot, and avoids direct friction between the pin 84 and the internal faces 115-3, 115-4 of the slot 115.

The slot 115 being oblique at least between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4, the relative movement of the slot 115 with respect to the pin 84 when the injector 36 moves between the first position and the second position induces a force on the pin 84. This force causes the pin 84 to move along an oblique trajectory having the shape of the slot 115. Also, the ring 72 is driven in rotation around the central axis 70.

Since the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4 of the slot 115 are substantially parallel, the rotation of the ring 72 around the central axis 70 takes place in a first direction when the injector 36 passes from the first position to the second position, and in a second direction opposite to the first direction when the injector 36 passes from the second position to the first position.

Preferably, the slot 115 is shaped so as to allow the movement of the ring between the first angular position and the second angular position. For this purpose, the axial dimension of the slot 115, and the angle that it forms in its portion between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4, are chosen so as to ensure that the movement of the slot 115 relative to the pin 84 allows the ring 72 to rotate about the central axis 70 by the angle necessary to move from its first angular position to its second angular position, and vice versa.

A thickness of the plate 110 is chosen so as to ensure that the rotational movement of the ring 72 around the central axis 70 does not cause the pin 84 to disengage from the slot 115 by passing radially under the plate 110. The thickness of the plate 110 is understood to be the dimension of the plate 110 substantially parallel to the mast 39 of the injector 36.

Advantageously, when the injector head 40 is moved from the second position to the first position, the ring 72 moves from the second angular position to the first angular position. As explained above, in the first angular position of the ring 72, the permeability of the injection system 23 decreases. This is illustrated in FIG. , on which the openings 94 of the ring 72 are opposite the air injection orifices 64. Conversely, the openings 92 of the ring 72, the section of which is larger than that of the openings 94 as explained above, are closed by the bowl 50, which is why they are not visible on the .

This configuration with the injector 36 in the first position and the ring 72 in the first angular position proves to be very advantageous during the ignition and re-ignition phases of the turbomachine. Indeed, to the advantages conferred by the first position of the injector 36 when the turbomachine is in ignition and re-ignition mode, it must be added that the reduction in air permeability makes it possible to increase the fuel enrichment rate in the combustion chamber 10. This enrichment rate is defined as the ratio between a fuel flow rate injected into the chamber 10 and an air flow rate injected into the chamber 10. This allows the flame core initiated in front of the spark plug 42 to reach the fuel recirculation zone of the injection system 23 more easily, and for the flame generated in the chamber 10 to propagate without difficulty to the neighboring injection systems. The chances of successfully igniting the combustion chamber 10 during the ignition or re-ignition phases of the turbomachine are thus increased. Furthermore, the re-ignition ceiling of the turbomachine is also increased when the permeability of the injection system decreases.

Also advantageously, when the injector head 40 is moved from the first position to the second position, the ring 72 moves from the first angular position to the second angular position. As explained above, in the second angular position of the ring 72, the permeability of the injection system 23 increases. This is illustrated in FIG. , on which the openings 92 of the ring 72 are opposite the air injection ports 64, while the openings 94 are closed by the bowl 50, and therefore, not visible on the .

This configuration with the injector 36 in the second position and the ring 72 in the second angular position proves to be very advantageous when the turbomachine operates in a speed above a certain threshold, for example above ground idle. Such a coupling is particularly advantageous when the turbomachine operates in full throttle conditions, such as for example during the take-off phase. Indeed, to the advantages conferred by the second position of the injector 36, it must be added that the increase in the permeability of the injection system 23 makes it possible to reduce the fuel enrichment rate in the combustion chamber 10. The combustion chamber is therefore depleted of fuel, which makes it possible to reduce pollutant emissions.

As indicated above, according to a non-limiting example, the injector 36 could be held axially in an intermediate position between the first position and the second position. In such a case, the position of the pin in the slot 115 is intermediate between that which it adopts when the injector 36 is in the first position and that which it adopts when the injector 36 is in the second position. This implies that the ring 72 rotates through an angle between the angle associated with the first angular position and the angle associated with the second angular position. The permeability of the injection system 23 could therefore be finely adjusted, which is advantageous during the intermediate phases of flight (i.e., when the turbomachine is not operating in the ignition, re-ignition, ground idle or full throttle phase). This is also advantageous when it is necessary to correct the position of the injector 36 on the casing 28 due to the different thermal expansions between the casing 28 supporting the injector 36 and the chamber 10 supporting the injection system 23.

In the examples of the figures, the pin 84 is engaged in the portion of the slot 115 between the first internal face 115-3 and the first surface 115-41 of the second internal face 115-4, whether the injector 36 is in the first position or in the second position. It should be noted, however, that in certain cases, in the second position of the injector 36, the pin 84 could be disposed between the first internal face 115-3 and the second surface 115-42 of the second internal face 115-4. In such cases, when the injector 36 advances axially toward the first position, the pin 84 comes into contact with one of the first internal face 115-3 or the second surface 115-42 of the second internal face 115-4. The pin 84 then slides along the first internal face 115-3 or the second surface 115-42 until it is inserted into the part of the slot 115 between the first internal face 115-3 and the first surface 115-41. When the pin 84 slides on the first internal face 115-3 or the second surface 115-42, the ring 72 is already rotated about the central axis 70.

Alternatively, the pin 84 could be arranged completely outside the slot 115, for example when the injector is disassembled. Due to the fact that the width L2 of the open end 115-1 of the slot 115 is greater than the circumferential distance D1 separating the secondary stop members 87-1, it is ensured that when the injector 36 is reassembled and advanced downstream, the pin 84 is in a position axially facing the slot 115, regardless of the angular position of the ring 72. Indeed, as explained above, thanks to the primary stop member 87 and the secondary stop members 87-1, the rotation of the ring 72 about the central axis 70 is limited to an angular distance equal to the difference between the circumferential distance D1 and the circumferential dimension L1 of the primary stop member 87. The width L2 being greater than the circumferential distance D1, the pin 84 is therefore always in a position capable of being engaged in the slot 115 during the movement axial of the injector 36, and this whatever the value of the circumferential dimension L1 of the primary stop member 87.

The present disclosure is not limited to the exemplary embodiments described above, only as an example, but it encompasses all the variants that a person skilled in the art may envisage in the context of the protection sought. For example, the ring 72 could comprise a plurality of pins 84 distributed circumferentially and projecting from its radially external surface. The mast 39 of the injector 36 could then carry a plurality of plates 110 comprising a respective slot 115, and arranged so that each pin 84 is engaged in the slot 115 of a respective plate 110. This makes it possible to limit the forces exerted on each pin 84 and on each plate 110 when the ring 72 is rotated about the central axis 70, thus reducing wear. It is noted that in such cases, each pin 84 (or at least some pins 84) may have a size and shape distinct from the other pins 84, with each slot 115 having a shape adapted to engage the respective pin 84 in the manner described above. The shape and size of each plate 110, or some plates 110, may also vary relative to the other plates 110.

Another variation could concern the positioning of the pin 84 and the slot 115. For example, the pin 84 could be carried by a radially internal surface of the plate 110, the slot 115 being arranged on the surface of the ring 72.

Claims (13)

Aircraft turbomachine assembly, the assembly comprising:
- a fuel injector (36) comprising an injector head (40) extending along a central axis (70), and
- an injection system (23) comprising a mixing bowl (50) mounted coaxially with the injector head (40), and a ring (72) rotating around said central axis (70),
the assembly further comprising means for supplying air inside the bowl (49, 64), these air supply means (49, 64) being regularly distributed around the central axis (70), said ring (72) being shaped so as to reduce or increase by rotation an air passage section in said air supply means (49, 64),
the assembly further comprising at least one controllable displacement device (57) of said injector (36), the at least one controllable displacement device (57) being configured to move the injector head (40) between a first position in which the injector head (40) is moved along said central axis (70) in a first direction towards an outlet plane of the mixing bowl (50), and a second position in which the injector head (40) is moved along said central axis (70) in a second direction opposite to said first direction relative to the first position, the assembly being configured to modify the angular position of said ring (72) relative to the air supply means (49, 64) when the injector head (40) is moved between the first position and the second position. An assembly according to claim 1, the assembly being configured so that the angular position of said ring (72) relative to the air supply means (49, 64) is modified so as to reduce the air passage section in said air supply means (49, 64) when the injector head (40) is in the first position. Assembly according to one of the preceding claims, the assembly being configured so that the angular position of said ring (72) relative to the air supply means (49, 64) is modified so as to increase the air passage section in said air supply means (49, 64) when the injector head (40) is in the second position. Assembly according to one of the preceding claims, the air supply means comprise an annular row of air injection orifices (64) regularly distributed on the bowl (50) around said central axis (70). Assembly according to one of the preceding claims, in which the injection system further comprises at least one auger (46, 48), said air supply means comprising a plurality of air introduction orifices (49) regularly distributed on said at least one auger (46, 48) around said central axis (70). Assembly according to one of the preceding claims, further comprising first form-fitting means (84) integral with the ring (72) and cooperating with second form-fitting means integral (115) with the injector (36), the first and second form-fitting means (84, 115) being configured to drive the ring (72) in rotation about said central axis (70) when the injector (36) moves between the first and second positions. Assembly according to the preceding claim, in which the first shape-connecting means comprise a slot (115), the second shape-connecting means comprising a pin (84) engaged in said slot (115). Assembly according to the preceding claim, in which the slot (115) is oblique with respect to said central axis (70). Assembly according to claim 7 or 8, in which the pin (84) carries a roller (83) capable of cooperating by rolling on internal faces (115-3, 115-4) of the slot (115), said internal faces (115-3, 115-4) being opposite each other. Assembly according to one of the preceding claims, in which the ring (72) comprises a primary stop member (87) arranged circumferentially between two static secondary stop members (87-1) carried by the injection system (23), said secondary stop members (87-1) being circumferentially spaced from one another. An assembly according to claim 10 and one of claims 7 to 9, the slot (115) comprising an open end (115-1) through which the pin (84) is engaged in said slot (115), the open end (115-1) having a width (L2) greater than a circumferential distance (D1) separating said secondary stop members (87-1). Assembly according to one of claims 7 to 11, in which the pin (84) is mounted movable on the ring (72) substantially parallel to said central axis (70). Turbomachine, such as a turbojet or a turboprop, comprising at least one turbomachine assembly according to one of the preceding claims.