EP1918570A2 - Fuel injector with accumulator volume segment - Google Patents

Abstract

The fuel injector has a fuel injector element (23) formed in needle shape operated by an actuator. The fuel injector has a storage volume segment (40) formed integral in injector interconnection (13,20,22). The storage volume segment has an upper part (45) and a lower part (46).

Description

State of the art

In modern internal combustion engines, especially in direct-injection internal combustion engines, it proves to be favorable for the combustion process to inject fuel several times at short intervals during the combustion process. This requires very fast switching injectors especially in high-speed internal combustion engines. Fast switching operations on injection valves (fuel injectors) lead to pressure oscillations in the fuel injector, in particular in connection with high hydraulic system pressures, which are likewise aimed at improving the combustion processes. In high-pressure accumulator injection systems (common rail), the system pressure is on the order of 1600 bar, however, as mentioned above, operating at higher system pressures to further optimize combustion.

High system pressures and the rapid successive switching operations can affect the closing process of a fuel injector so that undesirable effects in the combustion process and increased wear on mechanical components of the fuel injector can occur.

For damping pressure oscillations, storage volumes are suitable in conjunction with hydraulic throttle elements which are arranged in the immediate vicinity of the point of origin of the pressure oscillation. For this purpose, there are available an actuator space in which, for example, in fuel injectors, which are actuated by means of a piezoelectric actuator, the piezoelectric actuator is housed, and a nozzle chamber which can be filled with the liquid to be injected, for example of the fuel to be injected into the combustion chamber. However, in these spaces, ie the Aktorraum and the nozzle chamber voratbaren liquid volumes prove to be too small for effective damping damping occurring in terms of their damping effect. It is therefore desirable to have additional storage volumes in the fuel injector in the immediate vicinity of the place of origin of the pressure oscillations. usually to create a nozzle space. However, this has its limit in that it does not allow the limited installation space on the internal combustion engine usually to increase the outer diameter of a fuel injector.

Presentation of the invention

According to the invention, it is proposed to integrate in a fuel injector an additional storage volume which can be filled with fuel in order to dampen the pressure oscillations in the fuel injector after the injection. The additional storage volume integrated in the fuel injector is formed in a chamber, such as a storage volume segment. As a result of this additional storage volume segment to be integrated into the fuel injector, the fuel injector is lengthened by approximately 1 cm, resulting in a storage volume of 900 mm ³ that can be filled with fuel. If the inventively proposed storage volume segment is formed in double size, the result is a doubled storage volume for storable damping medium, such as fuel.

The additional storage volume segment which can be filled with the liquid to be injected, such as fuel, is preferably coupled hydraulically to a high-pressure region of the fuel injector via a throttle element, for example a hole throttle. The choke formed, for example, as a throttle valve, and the additional storage volume act as a damping element and can be easily adapted, in particular without increasing the outside diameter of the fuel injector, to the requirements to be controlled in terms of vibration technology. Hydraulic pressure oscillations in a fuel injector can be effectively reduced with such an additional storage volume segment. In an embodiment of the invention underlying idea, a storage volume segment between the nozzle body and a throttle plate of a fuel injector can be arranged. The length of the fuel injector only slightly extending additional storage volume segment, for example, positioned by elongated positioning pins with respect to the nozzle body and the throttle plate and clamped by a correspondingly extended trained nozzle clamping element, such as a nozzle lock nut, with the entire Injektorverband.

The additional storage volume segment shown in the embodiment variants is arranged very close to the point of origin of hydraulic pressure oscillations, such as the nozzle space, and thus has a very good effectiveness. By a corresponding variation of the axial length of the inventively proposed additional storage volume segment can be stored in this storable storage volume adapt to the vibration requirements. In a particularly advantageous manner, the inventively proposed additional storage volume segment does not increase the outer diameter of the fuel injector, but has a moderate effect on the length of the fuel injector. The inventively proposed storage volume segment can optionally be used on the injector when the vibration behavior of the function or the durability of the same require it.

With regard to the fuel injector, only the length of a nozzle tensioning element, such as a nozzle retaining nut and positioning pins for the positionally correct positioning of the additional storage volume segment within the fuel injector, are to be adjusted by the additional length thereof; all other components of the fuel injector can be taken over unchanged.

A required extension of the fuel injector in the axial direction is of the order of 10 mm and therefore falls very moderately to produce an additional storage volume of 1000 mm ³ . In particular, when the additional storage volume segment is formed in two parts, a relatively high volume utilization of the available installation space can be achieved with low production costs.

In a two-part embodiment of the additional storage volume segment, an upper part may be formed as a ring part and a lower part as an insert part. The lower part can, for example, be strongly cooled before being inserted into the fuel injector and compressed after heating by the thermal expansion and thus be fixed in position.

drawing

With reference to the drawing, the invention will be described below in more detail.

Figur 1

eine Darstellung wesentlicher Komponenten eines Kraftstoffinjektors gemäß des Standes der Technik mit einer vergrößerten Darstellung eines Ausschnittes A,

Figur 2

eine schematische Darstellung eines Dämpfungsvolumens für hydraulische Druckschwingungen, ein Speichervolumen, eine Speicherdrossel, eine Hochdruckversorgung umfassend,

Figur 3

ein Kraftstoffinjektor mit integriertem Zusatzspeichervolumen, welches als Speichervolumensegment ausgebildet ist,

Figur 4

eine Vertikal-Schnittdarstellung des erfindungsgemäß vorgeschlagenen Speichervolumensegmentes in Ebene B-B,

Figur 5

eine Ansicht des erfindungsgemäß ausgeführten Speichervolumensegmentes aus Richtung D,

Figur 6

einen Horizontalschnitt durch das erfindungsgemäß aufgeführte Speichervolumensegment in einer Ebene C-C und

Figur 7

eine Ansicht des erfindungsgemäß ausgeführten Speichervolumensegmentes aus Richtung E.

It shows:

FIG. 1

1 is an illustration of essential components of a fuel injector according to the prior art with an enlarged view of a section A,

FIG. 2

a schematic representation of a damping volume for hydraulic pressure oscillations, a storage volume, a storage throttle, comprising a high-pressure supply,

FIG. 3

a fuel injector with integrated additional storage volume, which is designed as a storage volume segment,

FIG. 4

a vertical sectional view of the present invention proposed storage volume segment in plane BB,

FIG. 5

a view of the inventively designed storage volume segment from direction D,

FIG. 6

a horizontal section through the inventively listed storage volume segment in a plane CC and

FIG. 7

a view of the inventively designed storage volume segment from direction E.

variants

The illustration according to FIG. 1 shows a fuel injector known from the prior art, partially cut away.

A fuel injector 1 shown in FIG. 1 comprises a holding body 2, to which a plug connection 3 shown in perspective is formed. The fuel injector 1 illustrated in FIG. 1 comprises an actuator cartridge which is accommodated within an actuator bore 11 in the holding body 2. From the detail of the fuel injector 1 shown in FIG. 1 on an enlarged scale, it can be seen that a high-pressure inlet 12 extends through the holding body 2, via which a control space designated by reference numeral 24 is subjected to fuel under system pressure. System pressure is understood below to mean a pressure level that prevails, for example, within a high-pressure reservoir body (common rail) of a high-pressure fuel injection system. In the high-pressure storage body (common rail), the system pressure is generated by, for example, a high-pressure pump or the like. The prevailing in the high-pressure accumulator (common rail) system pressure is via the high-pressure inlet 12, formed in a valve plate 13 hole and a formed in a throttle plate 30 inlet in the control chamber 24 of the fuel injector 1 as shown in Figure 1. The Aktorraumbohrung 11, in which the preferred trained as a piezoelectric actuator actuator for actuating the fuel injector 1 is housed, located in the low pressure region of the fuel injector 1. The liquid volume from the actuator chamber 11 from the control room Can be recorded, often proves to be too small for effective damping occurring pressure oscillations with respect to a storage effect.

The piezoelectric actuator used in the actuator cartridge for actuation of the fuel injector 1 indirectly presses with the interposition of a coupler piston 10 on a valve pin 14 which is biased by means of a valve spring 15. Below the valve pin 14, a channel passes through the throttle plate 30, which communicates hydraulically with the high-pressure region (bypass bore). The holding body 2 of the fuel injector 1, within which the high pressure inlet 12 extends, is connected via a nozzle retaining nut 22 with the nozzle body 20 in connection. Between these, the valve plate 13 and the throttle plate 30 are clamped. When tightening the nozzle retaining nut 22 with a defined tightening torque form holding body 2, valve plate 13, throttle plate 30 and nozzle body 20 is a prestressed Schraubverbund.

In the embodiment variant of the fuel injector 1 known from the prior art illustrated in FIG. 1, additional storage volumes in the fuel injector in the immediate vicinity of the nozzle space 21 are not available. For reasons of installation and the limited space in the cylinder head area of an internal combustion engine, an increase in the diameter of the fuel injector 1 is not possible.

From the representation according to FIG. 2, the hydraulic connection of a damper for damping hydraulic pressure oscillations is comprehensively represented by a storage volume, a storage throttle and a nozzle space.

From the schematic representation according to FIG. 2, it can be seen that the nozzle space 21 is acted upon by fuel under system pressure via the high-pressure inlet 12, which extends through the holding body 2 of the fuel injector 1. Furthermore, an additional storage volume 42 is acted upon at the same time with the interposition of a damper throttle 43 with a system under pressure fuel supply, which represents the additional, hydraulic pressure oscillations damping storage volume.

FIG. 3 shows the additional storage volume proposed according to the invention and integrated into the fuel injector, which is designed as a storage volume segment.

FIG. 3 shows that - enclosed by the nozzle retaining nut 22 - a storage volume segment 40 is accommodated between the nozzle body 20 and the throttle plate 30. The two-part storage volume segment 40 comprises an annular upper part 45 and an insert 46 designed as an insert, which are joined together Condition limit the storage volume 42. In the embodiment variant shown in FIG. 3, the storage volume segment 40 is clamped between the throttle plate 30 and an end face of the nozzle body 20. The opening in the valve plate 13 high pressure inlet 12 extends through the throttle plate 30 and from this through the lower part 46 of the storage volume segment 40. The high-pressure inlet 12 opens into the nozzle chamber 21 of the nozzle body 20. In this needle-shaped injection valve member 23 is received, which has a Covenant, on which a spring is supported, which makes a control chamber sleeve 25, which limits the control chamber 24, to the lower plan side of the insert formed as a lower part 46 of the storage volume segment 40 sealingly hiring. In addition, the nozzle chamber 21 formed in the nozzle body 21 is connected via a throttle 43 with the storage volume 42 in connection. The storage volume 42 is limited on the one hand by the upper part 45, which is annular and on the other hand limited by the formed as an insert part 46. Lower part 46 and upper part 45 of the storage volume segment 40 are preferably joined together to form an interference fit, resulting in the additional storage volume 42 shown in Figure 3, which is arranged via the damper throttle 43 in an optimal manner very close to the nozzle chamber 21, in which the hydraulic Pulsations in the form of pressure oscillations upon actuation of the preferably needle-shaped injection valve member 23 are induced.

From the high-pressure inlet 12, which extends through the holding body 2, an inlet throttle 32 is acted upon. Downstream of the inlet throttle 32, which is formed in the throttle plate 30, extends through the storage volume segment 40, a bore 44 which opens into the control chamber 24 in the nozzle body 20, which is bounded by the control chamber sleeve 25. Furthermore, through the storage volume segment 40 - but not lying in the illustrated sectional plane - runs a throttle bore for a drain throttle (see reference numeral 48 in Figures 5, 6 and 7).

Due to the direct connection of the additional storage volume 42 to the nozzle chamber 21, a good hydraulic efficiency with respect to the damping behavior of the storage volume segment 40 is ensured. The additionally buildable storage volume segment 40 is formed as a component which can be inserted without changes to adjacent components such as the nozzle body 20 and the throttle plate 30 in the immediate vicinity of the nozzle chamber 21 in the Injektorverbund.

The resulting in the nozzle chamber 21 of the fuel injector 1 pressure oscillate on the damper damper 43 in the additional storage volume 42 towards. In this case via the damper throttle 43 flowing volume flow is on and during the outflow From the additional storage volume 42 kinetic energy is converted into heat, which causes a damping of the pressure oscillations in the nozzle chamber 21. By varying the throttle cross section of the damper throttle 43 and the size of the additional storage volume 42 - formed by the storage volume segment 40 - the storage volume segment 40 can be optimally tuned to the damping occurring in the nozzle chamber 21 damping.

Since the storage volume segment 40 is inserted as an additional module between the nozzle body 20 and the throttle plate 30 of the fuel injector 1, the storage volume segment 40 takes over the hydraulic connection between the throttle plate 30 and the nozzle body 20, the nozzle chamber 21 and the control chamber 24. This is shown in the figures 4 to 7 shown.

FIG. 4 shows an enlarged view of the additional storage volume segment contained in FIG. 3 in the injector assembly.

The illustration according to FIG. 4 shows that the storage volume segment 40 is essentially formed from the upper part 45, which is designed as a ring part, and the lower part 46, which is an insert part. The upper part 45 and the lower part 46 are preferably joined together during assembly by means of a press fit, so that a contact surface 49 is set up in the interior of the storage volume segment 40. A sealing gap 27 is formed in the region of a second end face 51, which is opposite to the first end face 50 of the storage volume segment 40.

In the first end face 50 on the upper part 45 extends a semicircular first annular groove 41, which is shown in more detail in the plan view of FIG. The first annular groove connects the high-pressure inlet 12 with the bypass bore 31 extending in the throttle plate 30, see. FIG. 3.

In the second end face 51 of the formed as an insert part lower part 46, a second annular groove 47 extends, which is formed to extend in a circle. The second annular groove 47 is formed analogously to the underside of the throttle plate 30, which otherwise - in the absence of additional storage volume segment 40 - represents the hydraulic connection to the nozzle body 20.

The annularly formed storage volume 42, bounded by the outer wall of the lower part 46 designed as an insert part, and the inner wall of the upper part 45 designed as a ring part, are moved from the bore 44 to the inlet throttle and from the high-pressure inlet 12 traversed. Reference numeral 43 marks the damper throttle point, via which the additional storage volume 42 of the additional storage volume segment 40 is hydraulically connected to the nozzle chamber 21 of the fuel injector.

FIG. 5 shows a plan view of the additional two-part storage volume segment shown in section in FIG. 4.

In the plan view of the storage volume segment 40 shown in FIG. 5, it can be seen that in the first end face 50, the first annular groove 41 extends semicircularly and hydraulically connects the high-pressure inlet 12 to the bypass bore 31. Furthermore, from the plan view according to FIG. 5, positioning bores 34 emerge, in which positioning pins 33, not shown in FIG. 5, run. With reference numeral 44, the bore is designated, which extends below the formed in the throttle plate 30 inlet throttle 32 through the storage volume segment 40. Reference numeral 48 denotes the bore, which is connected downstream of the outlet throttle for pressure relief of the control chamber 24. The plan view of the additional storage volume segment 40 shown in FIG. 5 shows the first end face 50 of the upper part 45 designed as a ring part. The sectional profile IV-IV corresponds to the illustration of FIG. 4.

The illustration according to FIG. 6 shows the sectional profile through the storage volume segment designated VI-VI in FIG.

The sectional view in FIG. 6 shows that the upper part 45 designed as a ring part surrounds the lower part 46 formed as an insert part annularly. Reference numeral 43 indicates the damper throttle in the bottom of the formed as an insert part 46. Reference numeral 27 designates the sealing gap 27, which is also shown in FIG. 4, which results in the joining of the two-part storage volume segment 40 shown in FIG. 2 as an interference fit between the upper part 45 and the lower part 46 enclosed by it. From the illustration according to FIG. 6, it can be seen that the bore 44 for the inlet throttle and the high-pressure inlet 12 run in the sectional plane according to FIG. 4, while the outlet throttle bore 48 lies in front of this and is therefore not reproduced in the sectional view according to FIG. With reference numeral 33 positioning pins are indicated, which are in the already indicated in Figure 5 positioning bore 34.
The lower part 46 can be joined to the upper part 45 by shrinking or by pressing in such a way that the required tightness can be reliably established at the sealing gap 27. The high-pressure bore 12 shown in the sectional view according to FIG. 6 represents the connection between the supply line of the fuel to be injected and the Nozzle space 21 ago. The bore 44 in the sectional plane according to FIG. 4 and shown in the sectional representation in FIG. 6 for the inlet throttle establishes the connection between the inlet throttle in the throttle plate 30 and the control chamber 24. The semicircular first annular groove 41 shown in the plan view according to FIG. 5 establishes the connection of the bypass bore 31 in the throttle plate 30 with that of the high-pressure inlet 12.

The illustration according to FIG. 7 shows a view of the storage volume segment, shown in section in FIG. 4, in two parts, from the underside.

From the illustration according to FIG. 7, it can be seen that the second annular groove 47 extends in a circle on the second end face 51 of the two-part storage volume segment 40. The second annular groove 47 on the second end face 51 encloses the sealing gap 27 concentrically. In the second end face 51 of the additional storage volume segment 40 open the high-pressure inlet 12, the bore 44 for the inlet throttle 32, the outlet throttle bore 48 and the damper throttle 43, which is shown in the sectional view of Figure 6 and in the sectional view of Figure 4. About the damper throttle 43 are the additional storage volume 42 with the nozzle chamber 21 in conjunction, so that occurring pressure pulsations or pressure oscillations can be attenuated directly in the place of origin. Kinetic energy is converted into heat via the damper throttle 43, which causes the damping of the resulting pressure oscillations in the nozzle chamber 21. By varying the throttle cross section of the damper throttle 43 and the storage volume 42, the storage volume segment 40 can be optimally adapted to the damping of pressure oscillations or pressure pulsations occurring. A further advantageous effect of the memory volume segment 40 shown in detail in FIGS. 4 to 7 is the fact that the surface pressure between the throttle plate 30 is formed by the first annular groove 41 in the first end face 50 and the second, annular annular groove 47 on the second end face 51 and the nozzle body 20 can be made significantly, resulting in a leak-free Injektorverbund result.

Claims (10)

Fuel injector (1) for injecting fuel into the combustion chamber of an internal combustion engine, having a preferably needle-shaped injection valve member (23) which can be actuated by means of an actuator (10), characterized in that the fuel injector (1) has a storage volume segment (40) formed in one piece Injector composite (2, 13, 20, 22). Fuel injector (1) according to claim 1, characterized in that the at least one piece formed storage volume segment comprises an upper part (45) and a lower part (46). Fuel injector (1) according to claim 2, characterized in that the at least one-part formed storage volume segment (40) formed as a ring part upper part (45) and formed as an insert part lower part (46), which in the way of an interference fit (27, 49) joined together are included. Fuel injector (1) according to claim 1, characterized in that the storage volume segment (40) contains a damper throttle (43), via which a storage volume (42) storable in the storage volume segment (40) can be hydraulically connected to a nozzle space (21) of the fuel injector (1) Connection stands. Fuel injector (1) according to claim 1, characterized in that the storage volume segment (40) at least one end face (50, 41) at least one groove (41, 47), which hydraulic connections (12, 44, 48) between the nozzle space and a recorded in Injektorverbund throttle plate (30) are produced. Fuel injector (1) according to claim 5, characterized in that in the first end face (50) a first annular groove (41) extends semicircular, which connects the high-pressure inlet (12) with a bypass bore (31) of the throttle plate (30). Fuel injector (1) according to claim 5, characterized in that on the second end face (51) of the storage volume segment (40), in particular of the insert part formed lower part (46) extends a second annular groove (47) extending in a circle. Fuel injector (1) according to claim 4 and 5, characterized in that in the holding body (2) formed high-pressure inlet (12) through the throttle plate (30) in the bore (44) which opens into the control chamber (24) of the fuel injector , Fuel injector (1) according to claim 1, characterized in that the control chamber (24) for actuating the preferably needle-shaped injection valve member (23) by a preferably needle-shaped injection valve member (23) supporting the control chamber sleeve (25) is limited. Fuel injector (1) according to one or more of the preceding claims, characterized in that the storage volume (42) of the storage volume segment (40) represents an additional storage volume of the order of 1000 mm ³ .

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