NL1041560B1

NL1041560B1 - Rotating fuel injector for internal combustion engines.

Info

Publication number: NL1041560B1
Application number: NL1041560A
Authority: NL
Inventors: Tjeerd Sijtse Ijsselstein Ing
Original assignee: Cereus Tech B V
Priority date: 2015-11-06
Filing date: 2015-11-06
Publication date: 2017-06-02
Also published as: WO2017078516A1

Abstract

The present invention relates to fuel injectors in general and rotating fuel injectors for internal combustion engines in particular. The rotating or rotary fuel injector according to the present invention comprises a higher dynamic axial load carrying capacity of the rotating fuel injector parts. This is achieved by providing the rotating injection part of the rotating fuel injector with a bidirectional hydraulic thrust bearing. Furthermore, the rotating fuel injector includes an improved injection needle oscillation damping feature, which prevents or minimizes hammering of the injection needle on the seat of the injection nozzle with the pertaining wear and noise.

Description

ROTATING FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES

FIELD OF THE INVENTION

The present invention relates to fuel injection devices in general and to rotating fuel injection devices for internal combustion engines in particular.

BACKGROUND OF THE INVENTION

Internal combustion engines of for example power generation equipment, road vehicles, airplanes, boats and ships are important sources of harmful emissions such as CO2, NOx and particulate matter (PM). NL 2001069 discloses a rotating fuel injector for internal combustion engines which tackle the emissions of internal combustion engines at the source, i.e. inside the combustion chamber of the internal combustion engines. The rotating fuel injector helps in reducing the fuel consumption and therefore the emission of CO2. In addition, the rotary injection of fuel prevents or minimizes the formation and consequently the emission of PM and NOx.

In view of the exposure of moving parts of the rotating fuel injector to the harsh conditions inside a combustion chamber of an internal combustion engine the operating lifetime of rotating fuel injectors according to the prior art tends to be limited. For a broad adoption of rotating fuel injection with the pertaining beneficial environmental effects the rotating fuel injectors shall have a mean time between failures (MTBF) that is comparable to that of static fuel injectors according to the prior art.

SUMMARY OF THE INVENTION

The rotating or rotary fuel injector according to the present invention comprises a higher dynamic axial load carrying capacity of the rotating fuel injector parts. This is achieved by providing the rotating injection part of the rotating fuel injector with a bidirectional hydraulic thrust bearing. Furthermore, the rotating fuel injector includes an improved injection needle oscillation damping feature, which prevents or minimizes hammering of the injection needle on the seat of the injection nozzle with the pertaining wear and noise.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic view of a partially longitudinally sectioned embodiment of the rotating fuel injection device according to the invention; FIG. 2 is a schematic representation of a part of the rotating fuel injector with an embodiment of the bi-directional hydraulic thrust bearing according to the invention; FIG. 2a is a detail of a check valve pertaining to the embodiment of the bidirectional hydraulic thrust bearing as shown in FIG. 2; FIG. 3 is a schematic longitudinal section of a part of an embodiment of the injection part of a rotating fuel injector according to the invention; FIG. 3a is a schematic detail of the longitudinal section of the embodiment of the injection part of a fuel injector according to the invention as shown in FIG. 3; FIG. 3b is a schematic detail of the longitudinal section of the embodiment of the injection part of a fuel injector according to the invention as shown in FIG. 3; FIG. 4 is a schematic view of a an embodiment of the rotating fuel injector with an impeller; FIG. 5 is a schematic view of a an embodiment of the rotating fuel injector without an impeller.

Identical or similar parts have been designated with identical or similar reference numbers in all drawings.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a schematic view of a partially longitudinally sectioned embodiment of the rotating or rotary fuel injection device according to the invention. In this embodiment the rotary injection device comprises: a housing 1 which may be connected rigidly to the combustion chamber of an internal combustion engine; an injection part 2, hereinafter also referred to as rotating injection part 2, which is rotatably connected to the housing and which is drivable by means of an actuator in order to rotate relative to the housing about an essentially central axis; a supply conduit which is fluidically connected to the combustion chamber for the pressurized introduction of a fuel into the combustion chamber and which comprises a fluid-tight coupling between the housing and the injection part; an injection nozzle 3 which is rigidly connected to the injection part and fluidically connected to the supply conduit for the introduction of fuel into the combustion chamber, while the injection nozzle rotates; an impeller in the immediate vicinity of the injection nozzle 3 in order to further promote mixing inside the combustion chamber.

In a number of other embodiments of the rotary fuel injection device according to the invention the injection device comprises at least one further supply conduit for the pressurized introduction of a fluid into the combustion chamber of an internal combustion engine. The embodiments of the fuel injection device of the latter type enable the successive or simultaneous introduction of various combinations of fuels and/or moderators into the combustion chamber of internal combustion engines under beneficial mixing conditions.

The rotary fuel injector according to the invention further comprises an hydraulic thrust bearing to allow dynamic axial loading of the injection part while the injection part is rotating. Although the dynamic axial load on the rotating injection part is expected to be higher in an outward direction viewed from inside the combustion chamber, the injection part is also expected to experience dynamic axial loading in the opposite direction.

Therefore, at least one of the preferred embodiments of the rotary fuel injector according to the invention comprises an hydraulic thrust bearing that can accommodate bi-directional dynamic axial loading of the injection part while simultaneously allowing essentially smooth rotation of the injection part. The latter type of thrust bearing will hereinafter be referred to as a bi-directional hydraulic thrust bearing. Although the embodiment of the rotating fuel injection device shown in FIG. 1 includes the bi-directional hydraulic thrust bearing according to the invention, the mode of operation of the bearing will be explained by means of the simplified embodiment of a part of the rotating fuel injection device shown in FIG. 2. FIG. 2 is a schematic representation of a part of the rotating fuel injector with an embodiment of the bi-directional hydraulic thrust bearing according to the invention. FIG. 2 shows a part of the rotatable injection part 2 whereby the injection part 2 comprises a section that fulfills the role of a piston 4. In this embodiment the piston 4 has a relatively short length in proportion to its diameter. The invention also covers pistons with other length to diameter ratios. The bi-directional thrust bearing comprises the creation of a pressurized cushion of a hydraulic medium inside hydraulic bearing chambers 5a and 5b at either end faces of the piston 4. The piston 4 may comprise one or more circumferential pressure equalizing grooves on its outer surface with the object of minimizing leakage losses via the piston. This piston rotates in the housing supported by the hydraulic cushions in the hydraulic bearing chambers 5a and 5b and serves as the top bearing of the rotating injection part 2. In the axial position of the piston 4 as shown schematically in FIG. 2 the piston blocks the passage of hydraulic medium from the hydraulic bearing chambers 5a and 5b into the return channel 6. If the rotating injection part 2 moves slightly upwards, for example due to an ignition explosion inside the combustion chamber of the engine, hydraulic medium from the lower hydraulic bearing chamber 5b will flow into the return channel 6. When that happens the hydraulic medium that is removed from the lower hydraulic bearing chamber 5b will be replenished automatically through the hydraulic medium inlet 7b which comprises a needle type check valve. In case of a downward movement of the injection part 2 some hydraulic medium may be drained from the upper hydraulic bearing chamber 5a and automatic replenishment will occur through the hydraulic medium inlet 7a. The check valves in the inlet lines 7a and 7b are oriented to allow fluid flow only towards a hydraulic medium chamber.

The hydraulic medium in the bi-directional hydraulic thrust bearing may comprise for example fuel, oil, water, coolant or any other fluid with properties that are suitable for this purpose. FIG. 2a is a detail of the spring loaded check valve shown in respectively hydraulic medium inlet 7a and 7b. The valves are characterized by the fact that the valves comprise an essentially cylindrical needle with a conical end that mates with a conical seat inside the conduit. The cylindrical section of the valve needle ensures that the needle remains centered and closes the valve properly even if the spring would not load the needle fully axially. In order to allow passage of the medium past the needle upon lifting of the needle from the seat, the needle comprises one or more longitudinal grooves in its outer surface.

For fuel injectors of internal combustion engines, both standard static fuel injectors and rotating fuel injectors, it is important that the actuating spring of the injector needle only exerts an axial force on said injector needle. This prevents bending of the needle thus preventing friction and extra wear.

Reduction of the noise associated with the fuel injection system is another important object. In modern engines the fuel injection pressure tends to be very high. This may result in high frequency oscillation of the injection needle, which usually has a lift that is limited to a few tens of a millimeter, alternately hammering on the injection nozzle seat and against the stop.

Under certain circumstances the oscillating spring loaded injection needle system may attain its resonance frequency, which results in a high noise level. Moreover, the supply of fuel is interrupted every time the needle hits the injection nozzle seat. For rotating fuel injectors of an internal combustion engine an uninterrupted supply of fuel during the complete injection time is desirable. FIG. 3 is a schematic longitudinal section of a part of an embodiment of the injection part 2 of a rotating fuel injector according to the invention with a spring loaded injection needle 8. In this drawing the needle is not longitudinally sectioned. For the transfer of the force exerted by the spring 9 onto the injection needle 8, the fuel injector comprises a spring carrier 10. In an embodiment of the fuel injector the spring carrier 10 has a cylindrical axial guide, hereinafter also referred to as axial guide, on either ends of the spring. These axial guides ensure that the spring carrier can only move axially and does not exert radial forces on the injection needle even if the spring is not fully centered. The axial guides of the spring carrier are not necessarily limited to a cylindrical shape. FIG. 3a is a schematic detail of the longitudinal section of the embodiment of the injection part of a fuel injector shown in FIG. 3, wherein a first end of the spring 9 is supported by the collar of a first cylindrical axial guide 10a of the spring carrier 10. FIG. 3a also shows an example of the engagement between the spring carrier and the injection needle 8. Since the spring carrier 10 can only move axially it can only load the needle 8 axially. Also shown in FIG. 3a is the stop 11 that limits the upward movement, the lift, of the needle 8. FIG. 3b is a schematic detail of the longitudinal section of the embodiment of the injection part of a fuel injector shown in FIG. 3, showing the second end of the spring and the second cylindrical axial guide 10b of the spring carrier 10 which can move axially in a bore in the body of the injection part 2 with a close sliding fit. In this context a close sliding fit may for example refer to a tolerance of minimum 2 micrometers and maximum 12 millimeters with a mean tolerance of approximately 5 micrometers. This close sliding fit may already help in dampening vibrations of the spring, spring carrier and needle system. However, the invention includes an additional feature for vibration dampening. In general, a minimum amount of fuel leaks upwards along the injection needle 8 towards the cavity with the spring and in prior art fuel injection devices this cavity has a drainage opening through which the fuel is returned to the fuel tank or to a fuel pump suction line. In the rotating fuel injector according to the present invention, which does not have a drainage opening, the leaking fuel that enters the cavity with the spring and spring carrier will be forced to exit through small channels in the spring carrier. In the embodiment shown in the detail of FIG. 3b the spring carrier has an essentially transverse bore 12 which is fluidically connected to an essentially axial bore 13 in the spring carrier, which axial bore 13 extends all to the way to the end face of the second cylindrical axial guide 10b. In view of the close sliding fit between the second cylindrical axial guide and the body of the injection part the fuel that leaks into the cavity with the spring and spring carrier will be forced mainly into the transverse bore 12 and then through the axial bore 13. Depending on the diameter of the transverse bore 12 and the axial bore 13 and on the length of the axial bore 13 the degree of dampening of vibrations of the needle, spring and spring carrier system can be influenced. The longer the axial bore 13 and/or the smaller the diameter of the axial bore 13 and/or the transverse bore 12 the more pronounced the dampening will be. Instead of or in addition to a combination of a transverse bore and an axial bore the spring carrier may comprise one or more bores that are drilled under an angle with the axis of the spring carrier in order to allow fuel to flow from the cavity with the spring to the top end face of the second axial guide 10b. The latter type of may hereinafter also be referred to as an inclined bore. Another option is to make a small bore in the wall of the injection part 2 that bypasses the section with the close sliding fit between the second axial guide 10b and the injection part 2. Such a bore may hereinafter be referred to as a bypass bore.

The diameter and the length of the bores may also be varied depending on the application and on the properties of the fuel, such as for example the viscosity and temperature. The combination of the transverse bore 12 and the axial bore 13, and/or an inclined bore may hereinafter also be referred to as the fluid flow restrictor of the spring carrier 10. Although in the strict sense a bypass bore as described above is not a feature of the spring carrier 10, the term fluid flow restrictor shall be interpreted as also including such a bypass bore, if present. The fluid flow restrictor ensures that the movement of the needle 8 during its lifting from the seat of the nozzle and during its return on the seat is slowed down slightly. This allows both a constant supply of fuel by the rotating fuel injector into a combustion chamber and a reduction in noise by eliminating or minimizing the high frequency hammering of the needle against the seat and the stop 11. A combination of features of the fuel injector according to the invention aimed at preventing hammering of the needle against the seat and/or against the stop will hereinafter also be referred to as an oscillation damper. The oscillation damper also reduces the risk of resonance of the needle, spring and spring carrier system which contributes further to a reduction of the noise from this system including the hydraulic hammering in the fuel supply lines and their related equipment.

Whereas in the above description the oscillation damper was described as a feature for rotating fuel injectors, the invention also comprises the use of the oscillation damper in static fuel injectors, meaning fuel injectors in which the fuel injection nozzle does not rotate relative to the housing of the injector and relative to the combustion chamber. FIG. 4 is a schematic view of a an embodiment of the rotating fuel injector. In this embodiment the fuel injector comprises an impeller that is rigidly connected to the injection part in the immediate vicinity of the injection nozzle of the fuel injector. During normal operation of the rotating fuel injector the impeller will rotate at the same rotational speed as the nozzle which will help in further homogenizing the fuel and air mixture inside the combustion chamber. FIG. 5 is a schematic view of a an embodiment of the rotating fuel injector without an impeller.

With respect to the construction materials of the components of the rotating fuel injector the invention covers any material with suitable properties. Where appropriate metallic materials seem the preferred choice. In one embodiment at least one wear prone part comprises a metal matrix composite or a ceramic material.

Clauses 1. An injection device for the injection of fuel into a combustion chamber of an internal combustion engine, wherein the injection device comprises - a housing (1) which is rigidly connected to the combustion chamber, an injection part (2) which is rotatably connected to the housing (1) and which is drivable by means of an actuator in order to rotate relative to the housing (1) about a central axis, a supply conduit which is fluidically connected to the combustion chamber for the pressurized introduction of a fuel into the combustion chamber and which comprises a fluid-tight coupling between the housing (1) and the injection part (2) , an injection nozzle (B) which is rigidly connected to the injection part (2) and which is fluidically connected to the supply conduit for the introduction of fuel into the combustion chamber, while the injection nozzle (3) rotates, characterized in that, the fuel injection device comprises a hydraulic thrust bearing between the housing (1) and the rotatable injection part (2), and/or an oscillation damper in the rotatable injection part (2). 2. Injection device according to claim 1, characterized in that, the hydraulic thrust bearing comprises a bi-directional hydraulic thrust bearing. 3. Injection device according to claim 2, characterized in that, the hydraulic thrust bearing comprises fuel, water or a coolant as hydraulic medium. 4. Injection device according to either of the preceding claims, characterized in that, the hydraulic thrust bearing comprises the combination of a piston (4) and hydraulic medium chambers (5a,5b) with hydraulic medium inlet lines (7a,7b) each of which lines comprises a check valve oriented to allow fluid flow only towards a hydraulic medium chamber (5a,5b). 5. Injection device according to claim 4, characterized in that, the check valve comprises a spring loaded needle valve wherein the fit between the needle and the valve body allows only axial movement of the needle. 6. Injection device according to any of the preceding claims, characterized in that, the injection part (2) comprises an oscillation damper comprising a spring carrier (10) with a first axial guide (10a) at a first end of the spring carrier (10) and a second axial guide (10b) at a second end of the spring carrier (10) whereby the second axial guide (10b) can move axially in a bore in the body of the injection part (2) with a close sliding fit. 7. Injection device according to claim 6, characterized in that, the spring carrier (10) comprises a fluid flow restrictor (12,13) that allows fluid to flow through the spring carrier.

Many changes can be made in the rotating fuel injection device described above without departing from the intent and scope thereof. It is intended therefore that the above description and accompanying drawings be interpreted as illustrative and not in a limiting sense.

Claims

An injection device for injecting a fuel into the combustion chamber of an internal combustion engine, the device comprising: a housing (1) fixedly connected to the combustion chamber, - an injection part (2) rotatably connected to the housing (1) and which is drivable by means of an actuator to rotate relative to the housing (1) about a central axis, a feed line which is in fluid communication with the combustion chamber to bring a fuel under pressure into the combustion chamber and which comprises a fluid-tight coupling between the housing (1) and the injection part (2), an injection mouth (3) which is fixedly connected to the injection part (2) and which comprises an atomizer with an atomizer opening which is in fluid communication with the supply line to bring the fuel into the combustion chamber , while the injection nozzle rotates, characterized in that the injection device has a hydraulic pivot bearing between the housing (1) and the rotatable injection part (2) and / or comprises a vibration damper in the injection part (2).

Injection device according to claim 1, characterized in that the hydraulic pivot bearing comprises a bidirectional hydraulic pivot bearing.

Injection device according to claim 2, characterized in that the hydraulic pivot bearing comprises fuel, water or a coolant as hydraulic medium.

Injection device according to one or more of the preceding claims, characterized in that the hydraulic pivot bearing comprises a combination of a piston (4) and hydraulic medium containing chambers (5a, 5b) with inlet pipes (7a, 7b) for hydraulic medium, each of the inlet conduits (7a, 7b) comprises a valve which is positioned such that it only permits fluid flow to chambers (5a, 5b) containing fluid medium.

Injection device according to claim 4, characterized in that the valve comprises a needle valve with a substantially cylindrical needle, the fit between the needle and the housing of the valve only allowing axial movement of the needle.

Injection device according to one or more of the preceding claims, characterized in that the injection part (2) comprises a vibration damper, which vibration damper comprises a spring carrier (10) with a first axial guide (10a) at a first end of the spring carrier (10) and comprises a second axial guide (10b) at a second end of the spring carrier (10), wherein the second axial guide can move in an axial direction with a sliding fit in the injection part (2).

Injection device according to claim 6, characterized in that the spring carrier (10) comprises a fluid flow resistance (12, 13) which allows flow of a fluid through the spring carrier.