WO2013153010A1

WO2013153010A1 - Injector of a modular common-rail fuel injection system with throughflow limiter

Info

Publication number: WO2013153010A1
Application number: PCT/EP2013/057268
Authority: WO
Inventors: Martin Bernhaupt
Original assignee: Robert Bosch Gmbh
Priority date: 2012-04-10
Filing date: 2013-04-08
Publication date: 2013-10-17
Also published as: JP2015512493A; EP2836696B1; EP2836696A1; JP5936764B2; AT512277B1; KR20140147100A; KR102049218B1; AT512277A4

Abstract

In the case of an injector (1) of a modular common-rail fuel injection system with a high-pressure accumulator (6) integrated in the injector body, the injector (1) comprises an injection nozzle (2), which has a nozzle needle (15) guided axially displaceably therein and surrounded by a nozzle chamber (19), a high-pressure line (8) which connects the high-pressure accumulator (6) to the nozzle chamber (19), and a holding body (5) which, at the face side, is screwed to the component, in particular accumulator pipe (25), which forms the high-pressure accumulator (6), through which holding body the high-pressure line (8) runs, wherein, downstream of the high-pressure accumulator (6) in terms of flow, there is arranged a throughflow limiter (26) for limiting the fuel flow rate delivered out of the high-pressure accumulator (6) to the injection nozzle (2). The throughflow limiter (26) is formed as a separate component which is placed between the holding body (5) and the accumulator pipe (25) and which is fixed by the screw connection between the holding body (5) and accumulator pipe (25).

Description

description

title

Injector of a modular common rail fuel injection system with flow restrictor

The invention relates to an injector of a modular common rail fuel injection system with a high-pressure accumulator integrated in the injector body, wherein the injector has an injection nozzle with axially displaceably guided, surrounded by a nozzle chamber nozzle needle, a high-pressure accumulator with the nozzle chamber connecting high pressure line and a holding body, the the front side with the component forming the high-pressure accumulator, in particular storage tube is screwed and through which the high-pressure line passes, wherein a flow restrictor for limiting the amount of fuel delivered from the high-pressure accumulator to the injection nozzle is arranged downstream of the high-pressure accumulator.

Such an injector is described in DE 10210282 AI.

Modular common rail systems are characterized in that part of the storage volume present in the system is present in the injectors themselves. Modular common-rail systems are used on particularly large engines where the individual injectors may be mounted at a considerable distance from each other. The sole use of a common rail for all injectors is not useful in such engines, as it would come to a massive slump in injection pressure due to the long lines during injection, so with prolonged injection duration, the injection rate would noticeably break. In such engines, it is therefore intended to arrange a high-pressure accumulator inside each injector. Such a design is referred to as a modular structure, since each injector has its own high-pressure accumulator and thus can be used as a stand-alone module. A high-pressure accumulator is not to be understood as an ordinary conduit, but rather as a pressure-resistant vessel with an inflow or outflow, the diameter of which compared to the high-pressure accumulator. Pressure lines is significantly increased so that from the high-pressure accumulator a certain amount of injection can be delivered without causing an immediate pressure drop.

Common rail systems can leak under unfavorable conditions, be it in the piping system or through defective injectors. Injectors with jamming nozzle needles, which lead to continuous injections into the combustion chamber, can cause considerable damage. These damages can lead to the fire of the vehicle or to the destruction of the engine. In order to avoid these dangers, flow rate limiters with a closing function are known, which close the inlet to the affected injector when a maximum removal quantity from the high-pressure accumulator is exceeded and thus decouple the injection-pump-side high-pressure from the injection-valve side.

In the case of injectors with integrated high-pressure accumulator, flow restrictors are usually arranged upstream of the storage volume. In so-called top-feed injectors (the fuel is supplied via a high-pressure port of the injector at the top of the high-pressure accumulator), the flow restrictor is usually attached to the upper end of the injector. In the case of so-called side-feed injectors (the supply of the fuel takes place via a lance which contacts the injector laterally), the flow restrictor is usually arranged in front of the pressure pipe stub in a T-piece. Furthermore, there are also arrangements in which the flow restrictor is arranged according to the current storage volume. Here, the flow restrictor housing is either pressed into the injector holder body or mounted with a retaining ring in the holding body.

Flow restrictors, which are arranged in terms of flow in front of the storage volume, inherently have the disadvantage that they are to set much inaccurate. The reasons for this are the dead time and the damping effect of the storage volume and the influence of different fuel parameters such as temperature and viscosity or the fuel type (diesel or heavy oil). A further disadvantage of the flow restrictor arranged in the flow medium in front of the storage volume is that a considerably larger amount can still be injected when closing the flow restrictor due to the expansion volume of the high-pressure accumulator. This property is repeatedly classified as very critical, especially in the very conservative business of large marine engines. The installation of the flow restrictor at the top of Topfeed injectors also increase the mass there and thus worsen the vibration load capacity of the injector. Sidefeed injectors require a complex T-piece. Thus, two different solutions are required for the two injector concepts, which increases the variety of components.

Flow restrictors, which are built according to the storage volume in terms of electricity, require a press fit in the holding body or complex bore intersections in the case of the pressed-in design. Both constructions are very unfavorable in terms of fatigue strength in the extreme pressure loads prevailing in common rail systems. For example, in systems with a system pressure of 2200 bar pressure loads of up to 2500 bar can be observed.

The present invention therefore aims to increase the fatigue strength, wherein in the holding body in particular interference fits and punctures for retaining rings or additional critical Bohrungsverschneidungen should be avoided. Furthermore, the same design concept for topfeed and sidefeed injectors should be used. Overall should be created with the same component cost as in the prior art training with a functionally optimal flow restrictor without the high pressure capacity of the holding body or the high-pressure accumulator is adversely affected.

To achieve this object, the invention provides in an injector of the type mentioned in essence that the flow restrictor is designed as a separate component, which is inserted between the holding body and the storage tube and is fixed by the screw of the holding body and storage tube. The fact that the flow restrictor is inserted between the holding body and the storage tube, the benefits of flow moderately built according to the storage volume flow restrictors are used. Characterized in that the flow restrictor is inserted between the holding body and the storage tube and fixed by the screwing of the holding body and storage tube, eliminates the need for pressing or securing using a locking ring, and there is a very simple construction, which has a high fatigue strength. The flow restrictor is in this case held only by the axial force generated during screwing of the holding body with the storage tube and clamped between these two components without the need for further fasteners as it were. So that when screwing the holding body with the storage tube on the

Flow limiting component acting torque does not lead to a rotation of the flow restrictor component, provides a preferred embodiment of the invention that the holding body and the flow restrictor are secured against rotation by means of an axial fixing pin.

On the one hand to provide a secure holding the flow restrictor and on the other hand a high pressure-tight connection, it is preferably provided that the flow restrictor has a shoulder with a conical first sealing surface which cooperates with a formed on a shoulder of the storage tube conical sealing surface.

Another high-pressure-tight connection is preferably achieved in that the flow restrictor component on the end face facing the holding body has a conical second sealing surface which cooperates with a conical sealing surface formed on an end face of the holding body. In this case, the arrangement of an anti-rotation in the form of locking pins can be omitted.

In the case of a conical sealing surface between the flow restrictor and the holding body must not be made with top feed injectors direct connection of the flow restrictor with the high pressure bore of the holder body, but it can be made such that the conical second sealing surface of the

Flow restrictor between a holding body and

Flow restrictor member formed cavity limited. The connection then takes place via the said cavity, which is particularly advantageous if a further parallel to the high-pressure line connected further high-pressure line passes through the holding body, which is on the one hand with the nozzle chamber and on the other hand with the high-pressure accumulator in combination. In this case, both the high-pressure line and the further high-pressure line open into the said cavity, so that both lines are supplied with fuel flowing through the flow restrictor.

Particularly preferably, the further high-pressure line is designed as a resonator line, which is connected to the high-pressure accumulator via a resonator throttle. Alternatively, the fluid connection of the flow restrictor to the two high-pressure lines can also take place in such a way that the high-pressure line and the additional high-pressure line are connected to the flow restrictor via a bore intersection formed in the flow restrictor component. This embodiment is particularly advantageous for sidefeed injectors, where it is necessary that when closing the flow restrictor no amount of fuel directly from the side fuel inlet to the injector (bypass of the flow restrictor) can flow.

In Sidefeed injectors, the connection of the fuel supply to the high-pressure accumulator is preferably such that the injector has a lateral connection for the fuel supply, which communicates with an inlet bore, whose first section is formed in the holding body and whose second section is the

Flow restrictor axially interspersed. In this case, a bypass of the flow restrictor is preferably prevented in that the flow restrictor component on the end face facing the holding body has a planar second sealing surface which cooperates with the planar end face of the holding body.

The design of the flow restrictor as a separate component increases the flexibility in its structural design. Preferably, it is provided in this context that the flow restrictor a housing with a high-pressure accumulator-side housing inlet and a holder body side housing outlet, a longitudinally displaceable in a chamber of the housing between a starting position and an end position and against the flow direction spring-biased closing member, which has at least one throttle having a channel Housing inlet and housing outlet connects hydraulically with each other and further controls a flow connection between the housing inlet and the housing outlet includes. In particular, it may be provided that a retaining ring fixed in the flow restrictor component defines the starting position of the closing member.

The invention further relates to the flow restrictor for use in the injector according to the invention, comprising a flow restrictor with a high pressure accumulator side inlet and a holder side outlet, a longitudinally displaceable in a chamber between a starting position and an end position and spring biased against the flow direction closing member having at least one throttle having Channel the inlet and outlet which hydraulically connects and which further controls a flow connection between the inlet and the outlet. The flow restrictor member is characterized by having a first inlet side axial portion and a second outlet side axial portion, the second portion having a larger diameter than the first portion, and the second portion having a tapered first sealing surface on a shoulder has on the opposite end face a second sealing surface which is in each case pressable against a mating surface. The arrangement of the sealing surfaces on the enlarged diameter formed second section ensures that the component between the holder body and the storage tube can be inserted and fixed by the screwing of the holding body and storage tube. The first section protrudes into the space of the high-pressure accumulator and is acted upon by the fuel pressure.

A preferred development provides in this case that the inner diameter of the first sealing surface is at a radial distance from the outer periphery of the first portion. As a result, when the flow restrictor member is installed, an annular gap is created between the first axial portion and the inside of the high pressure accumulator so that the fuel pressure is not limited only to the inside, i. in the flow restrictor, but also from the outside to the effect, so that a pressure-compensated area arises.

The invention will be explained in more detail with reference to embodiments shown in the drawing. 1 shows the schematic structure of an injector of a modular common rail fuel injection system according to the prior art, FIG. 2 shows a detailed view of the injector in region II of FIG. 1 in a first embodiment, FIG. 3 shows a detailed view of the injector in a second embodiment, Fig. 4 is a detail view of the injector in a third embodiment and Fig. 5 is a detail view of the injector in a fourth embodiment.

In Fig. 1, an injector 1 is shown having an injection nozzle 2, a throttle plate 3, a valve plate 4, a holding body 5 and a high-pressure accumulator 6, wherein a screwed to the holding body 5 nozzle retaining nut 7, the injection nozzle 2, the throttle plate. 3 and the valve plate 4 holds together. In the idle state, the solenoid valve 13 is closed, so that high-pressure fuel from the high-pressure accumulator 6 via the high-pressure line 8, the cross-connection 9 and the inlet throttle 10 flows into the control chamber 11 of the injection nozzle 2, the outflow from the control chamber 11 via the outlet throttle 12 but at the valve seat of the solenoid valve 13 is blocked. The one in the control room 11 applied system pressure presses together with the force of the nozzle spring 14, the nozzle needle 15 in the nozzle needle seat 16, so that the injection holes 17 are closed. If the solenoid of the solenoid valve 13 is actuated, it releases the flow through the solenoid valve seat, and fuel flows from the control chamber 11 through the outlet throttle 12, the solenoid valve armature chamber and the low pressure bore 18 back into the fuel tank, not shown. A equilibrium pressure defined in the control chamber 11 by the flow cross-sections of inlet throttle 10 and outlet throttle 12 is so small that the system pressure applied in the nozzle chamber 19 is able to open the nozzle needle 15, which is displaceable longitudinally in the nozzle body, so that the spray holes 17 are released and an injection takes place.

As soon as the solenoid valve 13 is closed, the drainage path of the fuel is blocked by the outlet throttle 12. Via the inlet throttle 10, fuel pressure is again built up in the control chamber 11, which generates an additional closing force which reduces the hydraulic force on the pressure shoulder of the nozzle needle 15 and exceeds the force of the nozzle spring 14. The nozzle needle 15 closes the way to the injection openings 17, whereby the injection process is terminated.

Parallel to the high-pressure bore 8, a resonator 20 may be arranged with a high-pressure memory-side resonator choke 21, with which occurring pressure peaks can be lowered more quickly.

The supply of high-pressure fuel from a high-pressure pump not shown in the injector 1, via a arranged on the top of the injector 1 high-pressure port 22 (topfeed injector). Alternatively, the fuel supply can take place via a high-pressure port 23 arranged laterally on the injector 1, in particular on the holding body 5, and an inlet bore 24 leading to the high-pressure accumulator 6 (sidefeed injector).

FIGS. 2 to 5 show a view of the detail X of FIG. 1 with the flow restrictor arranged between the storage tube 25, the high-pressure accumulator 6 and the holding body 5. The embodiments according to FIGS. 2 to 5 have in common that the flow regulator is formed in a separate flow restrictor component 26. The flow restrictor member 26 has a first axial portion 27 and a second axial portion 28, the second axial portion 28 having a larger outer diameter than the first axial portion 27 axial portion 28, the flow restrictor 26 has a shoulder with a tapered first sealing surface 29 which cooperates with a formed on a shoulder 30 of the storage tube 25 conical mating sealing surface. The shoulder 30 of the storage tube 25 is connected via an annular groove-like recess 31 with a thinner walled, provided with an internal thread 33 portion 32 of the storage tube 25. The flow restrictor 26 is inserted between the holding body 5 and the storage tube 25 and fixed by the screw connection of these two components. In this case, the flow restrictor 26 is secured by means of pins 34 against rotation. The seal to the holding body 5 takes place in the embodiment according to FIGS. 2, 3 and 5 via a flat sealing point, which is formed by a plane formed on the holding body 5 facing end face plane sealing surface, which cooperates with the flat end face of the holding body 5.

The flow restrictor member 26 has an inlet 36 and an outlet 37. In a chamber 38 a displaceably guided in the axial direction piston 39 is arranged, which is pressed by means of the compression spring 40 against the retaining ring 41. The piston 39 has a blind hole 42, which communicates on the one hand with the inlet 36 and on the other hand via a throttle bore 43 with the outlet 37. In operation, the amount of injection is removed from the chamber 38. As a result, the piston 39 moves against the spring force in the direction of the lower sealing seat 44, without, however, reaching it. During the non-injection time, the compression spring 40 pushes the piston 39 back to the starting position. The chamber 38 is in this case filled via the throttle 43 again. If the injection amount exceeds a defined maximum value, the piston 39 moves so far that the sealing seat 44 is reached and the injection is terminated. By the throttle 43 creates a pressure loss between the present in the blind hole 42 fuel and the chamber 38. When a defined throttle flow is exceeded, the piston 39 moves against the spring force in the direction of the lower sealing seat 44 and thus ends the injection.

In the embodiment according to FIG. 2, a single high-pressure line 8 is provided, which extends through the holding body 5. The fuel passing through the flow restrictor 26 passes directly into the high-pressure line 8 via a bore section 48.

In the embodiment according to FIG. 3, a further high-pressure line 20, which is designed as a resonator line, is arranged parallel to the high-pressure line 8 in the holding body 5 and communicates with the fuel supply via a resonator throttle 21. The two high-pressure lines 8 and 20 are by a in the

Flow restrictor 26 trained Bohrungsverschneidung 45 fueled.

In the embodiment according to FIG. 4 it is shown that the sealing of the

Flow restrictor 26 can be made to the holding body 5 in Topfeed injectors via a conical seal 46. In this case, the pins 34 can be omitted for the rotation. The conical sealing surfaces forming the conical seal 46 in this case delimit a hollow space 47 into which, on the one hand, the outlet 37 and, on the other hand, the high-pressure lines 8 and 20 open.

In the embodiment of FIG. 5 is a sidefeed injector, wherein the fuel via the inlet bore 24 from the holding body 5 via the

Flow restrictor 26 is guided in the high-pressure accumulator 6. The inlet bore 24 opens in this case via a storage throttle 49 in the high-pressure accumulator. 6

Claims

claims

1. Injector of a modular common rail fuel injection system with a high-pressure accumulator integrated in the injector body, wherein the injector having an injection nozzle axially guided therein, surrounded by a nozzle chamber nozzle needle, the high-pressure accumulator with the nozzle chamber connecting the high pressure line and a holding body having the front side with the high-pressure accumulator forming component, in particular storage tube is screwed and through which the high-pressure line, wherein a flow limiter for limiting the funded from the high-pressure accumulator to the fuel injection amount of fuel is arranged according to flow, characterized in that the flow restrictor (26) as a separate component is executed, which between the holding body (5) and the storage tube (25) is inserted and fixed by the screwing of the holding body (5) and storage tube (25).

2. An injector according to claim 1, characterized in that the holding body (5) and the flow restrictor member (26) by means of an axial pin (34).

are secured against rotation.

3. Injector according to claim 1 or 2, characterized in that the

Flow restrictor (26) has a shoulder with a conical first sealing surface (29) which cooperates with a on a shoulder (30) of the storage tube (25) formed conical sealing surface.

4. Injector according to claim 1, 2 or 3, characterized in that the

Flow restrictor (26) on the said holding body (5) facing end side has a conical second sealing surface which cooperates with a on one end face of the holding body (5) formed conical sealing surface.

5. An injector according to claim 4, characterized in that the conical second sealing surface of the flow restrictor member (26) defines a between the holding body (5) and flow restrictor member (26) formed cavity (47).

6. Injector according to one of claims 1 to 5, characterized in that through the holding body (5) parallel to the high-pressure line (8) connected further high-pressure line (20) extends, on the one hand with the nozzle chamber (19) and on the other hand with the high-pressure accumulator ( 6) is in communication.

7. An injector according to claim 6, characterized in that the further high pressure line (20) is designed as a resonator, which is connected via a resonator (21) with the high-pressure accumulator (6) in communication.

8. An injector according to claim 6 or 7, characterized in that the high-pressure line (8) and the further high-pressure line (20) open into the cavity (47).

9. Injector according to claim 6 or 7, characterized in that the high-pressure line (8) and the further high-pressure line (20) via a in the

Flow restrictor (26) formed Bohrungsverschneidung (45) are in communication with the flow restrictor.

10. Injector according to one of claims 1 to 9, characterized in that the injector (1) has a lateral connection (23) for the fuel supply, which communicates with an inlet bore (24) whose first portion in the holding body (5). is formed and whose second section is the

Flow restrictor (26) penetrated axially.

11. Injector according to one of claims 1 to 10, characterized in that the flow restrictor member (26) on the holding body (5) facing end face a plane second sealing surface (35) which cooperates with the flat end face of the holding body (5).

12. Injector according to one of claims 1 to 11, characterized in that the flow restrictor (26) comprises a housing with a high pressure accumulator side housing inlet (36) and a haltekörperseitigen housing outlet (37), in a chamber (38) of the housing between a starting position and a final Position longitudinally displaceable and against the flow direction spring-biased closing member (39) via at least one throttle (43) having channel the housing inlet (36) to the housing outlet (37) hydraulically connected to each other and further a flow connection between the housing inlet (36) and the Housing outlet (37) controls includes.

13. Injector according to claim 12, characterized in that a in the

Flow restrictor (26) fixed retaining ring (41) defines the starting position of the closing member (39).

14. A flow restrictor member (26) for use in an injector (1) according to any one of claims 1 to 13, comprising a flow restrictor having a high pressure accumulator side inlet (36) and a holder side outlet (37), one in a chamber (38) between an initial position and an end position longitudinally displaceable and counter to the flow direction spring-biased closing member (39) via at least one throttle (43) having channel the inlet (36) and the outlet (37) hydraulically connected to each other and further a flow connection between the inlet (36 and the outlet (37), characterized in that the flow restrictor member (26) has a first, inlet-side axial portion (27) and a second, outlet-side axial portion (28), the second portion (28) opposite the first portion (27) enlarged diameter, and that the second portion (28) at a Schu Lter a conical first sealing surface (29) and on the opposite end face a second sealing surface (35, 46) which is in each case can be pressed against a mating surface.

15. flow restrictor according to claim 14, characterized in that the second sealing surface (46) is formed conically.

16. flow restrictor according to claim 14 or 15, characterized in that the inner diameter of the first sealing surface (29) at a radial distance from the outer periphery of the first portion (27).

17. flow restrictor according to claim 14, 15 or 16, characterized in that in the flow restrictor member (26) fixed retaining ring (41) defines the starting position of the closing member (39).

18. flow restrictor according to one of claims 14 to 17, characterized in that the outlet (37) opens into a in the flow restrictor (26) formed bore intersection (45).

19 flow restrictor according to one of claims 14 to 18, characterized in that the second portion of an inlet bore (24) is penetrated.