EP2059671A1

EP2059671A1 - Injector for internal combustion engines

Info

Publication number: EP2059671A1
Application number: EP07787434A
Authority: EP
Inventors: Francois Rossignol; Friedrich Howey; Olivier Charvet; Tony Dumont
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-08-30
Filing date: 2007-07-12
Publication date: 2009-05-20
Anticipated expiration: 2027-07-12
Also published as: CN101512139B; CN101512139A; EP2059671B1; WO2008025607A1; DE502007003783D1; DE102006040645A1

Abstract

The invention relates to an injector for injecting highly pressurized fuel into a combustion chamber of an internal combustion engine, having an injector body (1) in which a nozzle needle (10) is arranged so as to be longitudinally movable and which, by means of its longitudinal movement, controls the opening of at least one injection opening (12) by interacting with a valve seat (13). A control space (16) is formed in the injector, which control space (16) can be filled with highly pressurized fuel, wherein the fuel pressure in the control space (16) serves to at least indirectly exert a closing force on the nozzle needle (10) in the direction of the valve seat (13). The control space (16) can be connected by means of a control valve (8) to a leakage oil space (32), such that the control space (16) can be relieved of pressure, wherein the control valve (8) has a control valve element (30) which can be moved by an actuator (33). A high-pressure inflow tube (25) is arranged in the injector body (1), which high-pressure inflow tube (25) conducts the compressed fuel to the control space (16), wherein the control valve element (30) is mounted, so as to be movable in a sliding fashion, on the high-pressure inflow tube (25).

Description

description

title

Injector for internal combustion engines

State of the art

The invention relates to an injector for injecting fuel under high pressure directly into the combustion chamber of self-igniting internal combustion engines.

For the introduction of fuel directly into the combustion chamber of self-igniting internal combustion engines, so-called common-rail systems are currently being used increasingly, especially in passenger cars. The pressure is generated centrally by a high-pressure pump and stored in a high-pressure accumulator, the so-called rail. From there, the compressed fuel is injected via injectors into the various combustion chambers of the internal combustion engine. One of the advantages of doing that is that

Injection pressure, that is, the fuel pressure generated by the high-pressure pump in the rail, can be adapted to the load and speed of the internal combustion engine. Thus, an increased energy demand is reduced by the compression of unneeded fuel.

In order to achieve the shortest possible switching times, that is, in order to move as quickly as possible the nozzle needle that opens or closes the actual Einspritzöffhungen, the control valve is often placed near injectors in the nozzle needle, so that the hydraulic connections are correspondingly short. The high-pressure passage, via which the compressed fuel from the rail is led to the injection openings, must consequently be guided past the control valve, which, with respect to the substantially cylindrical shape of the injector, causes an eccentricity of the high-pressure line and therefore requires corresponding structural measures. Since there is a very high pressure in the inlet channel, which depending on the injection system may be 1500 to 2000 bar (150-200 MPa), the wall thickness must not fall below certain values. This places narrow limits on the further streamlining of the injectors. The central Zuführang of fuel in an injection valve is known for example from the published patent application DE 199 59 304 Al. The fuel injection valve shown here is used with a so-called distributor pump. These distributor pumps do not provide a constant injection pressure, but produce for each injection a separate fuel surge, which is fed to the individual injector and then opens the nozzle needle against the force of a closing spring. The fuel injection valve shown in DE 199 59 304 Al has a central fuel inlet, which has substantially the shape of a tube and on whose brennraumsei- ended end, the nozzle needle is guided. Due to the central guidance of the fuel injection valve can be made slim and takes in the cylinder head of the engine accordingly little space away.

A similar construction is known from published patent application DE 32 29 828 A1. Again, it is a fuel injector that is used with a distributor pump. In contrast to the above, known from the prior art, fuel injection valve here moves the nozzle needle in synchronism with the tubular body through which the compressed fuel is introduced. The fuel is supplied via a slide seal, which is secured at the end remote from the combustion chamber between the inlet pipe and a specially fitted body.

However, the known fuel injection valves are not applicable to common rail systems, since they have no control valve, with which the closing force can be regulated on the nozzle needle. On the other hand, in the known injectors, which in

Common rail systems used to achieve further slimming only with great difficulty, since the material in which the inlet channels, which pass the fuel on the control valve, formed, can not withstand an even higher load usually without it Damage to the injector comes.

Disclosure of the invention

Advantages of the invention The injector according to the invention has the advantage that it can be made very slim and thus requires little space and thereby has the full functionality of a common rail injector. For this purpose, a high-pressure inlet pipe is arranged in the injector body, which conveys compressed fuel to the control chamber, wherein the control valve member is slidably mounted on the high-pressure inlet pipe. By this arrangement of the control valve member can be a very compact control valve construct, the fuel is passed through quasi through the control valve, which allows a very slim and thus compact design of the injector. In addition, cost advantages arise from the fact that the holding body to which the injection nozzle is attached, is no longer exposed to the fuel pressure and therefore can be made of a cheaper material; Under certain circumstances, even a production of a low-cost plastic is possible.

By the dependent claims advantageous developments of the subject invention are possible. Advantageously, the high-pressure inlet pipe runs centrally in the injector body, so that it is arranged substantially in alignment with the nozzle needle. This arrangement has a high symmetry, which allows the use of many rotationally symmetrical components and makes the production correspondingly low.

In a further advantageous embodiment, the high-pressure inlet pipe opens at its outlet end into a manifold formed in the injector body, from which the inlet throttle, which supplies the control chamber with high fuel pressure, and an inlet channel branch off, wherein the inlet channel supplies the injection openings with fuel. The distributor space offers a great deal of freedom in arranging the fuel ducts within the injector, so that it can be adapted more easily to different requirements.

In a further advantageous embodiment, the control valve member is formed substantially sleeve-shaped and surrounds the high-pressure inlet pipe. By this arrangement of the control valve member an exact guidance with minimal space requirement is possible. In this case, the control valve member preferably cooperates with a valve seat, which surrounds the high-pressure inlet pipe, so that an annular space which also surrounds the high-pressure inlet pipe can be connected by the movement of the control valve member with a leakage oil space in the injector. Advantageously, the actuator that moves the control valve member is - A -

an electromagnet, which can also be arranged around the high-pressure inlet pipe, so that there is also a high degree of symmetry.

drawing

In the drawing, various embodiments of the injector according to the invention are shown. It shows

1 shows a longitudinal section through a first embodiment of an injector according to the invention, Figure 2 shows another embodiment also in longitudinal section,

Figure 3 shows an enlarged view of another embodiment, which is also shown in longitudinal section and Figure 4 again the entire injector - apart from the combustion chamber side

Tip of the nozzle - with the appropriate fuel connections

Description of the embodiments

FIG. 1 shows a longitudinal section of a first exemplary embodiment of the injector according to the invention. The injector has an injector body 1 which comprises a holding body 2, a throttle body 4 and a nozzle body 5. The nozzle body 5 is under

Interposed layer of the throttle plate 4 clamped by a clamping nut 7 against the holding body 2, so that all parts of the injector body 1 are pressed firmly against each other and are stationary to each other.

In the nozzle body 5, a bore 9 is formed, which is bounded on the combustion chamber side by a conical valve seat 13. From the valve seat 13 go from several injection openings 12, through which the fuel can be injected into a combustion chamber of an internal combustion engine. In the bore 9, a piston-shaped nozzle needle 10 is arranged longitudinally displaceable, which is guided in a central portion in the bore 9. Between see the nozzle needle 10 and the wall of the bore 9, a pressure chamber 11 is formed, can flow through the fuel, which is compressed to high pressure, in the direction of the injection openings 12. If the nozzle needle 10 in contact with the valve seat 13, the Einspritzöffhungen 12 are closed and an injection does not take place. If an injection takes place, then the nozzle needle 10 lifts off from the valve seat 13 and releases the injection openings 12. To control the longitudinal movement of the nozzle needle 10, the pressure in a control chamber 16 which is bounded by the valve seat facing away from the end face of the nozzle needle 10, a sleeve 15 and the throttle body 4 is used. The sleeve 15 is in this case guided on the nozzle needle 10, wherein between the sleeve 15 and a support ring 17 which on a shoulder of the

Nozzle needle 10 rests, a closing spring 14 is arranged under pressure bias. By the closing spring 14, the sleeve 15 is pressed against the throttle body 4 on the one hand, and on the other hand, the nozzle needle 10 experiences a force in the direction of the valve seat 13, so that the nozzle needle 10 is pressed in the absence of further forces on the valve seat 13 and the Einspritzöffhungen 12 closes.

For supplying fuel, which was compressed by a pump to high pressure, is used in the holding body 2 and the throttle body 4 arranged high-pressure inlet pipe 25. The nozzle-side end of the high-pressure inlet pipe 25 is in this case sealingly guided in a bore 21 which is formed in the throttle body 4. At the bottom of the bore 21, a distributor space 23 is formed, from which on the one hand an inlet throttle 22 leads into the control chamber 16 and on the other hand an inlet channel 20 into the pressure chamber 11.

In addition, an outlet throttle 24 is formed in the throttle body 4, which connects the control chamber 16 with an annular space 27, which is formed in the throttle body 4 and surrounds the high-pressure inlet pipe 25. In this case, the annular space 27 extends into a leakage oil space 32 which bounds the part of the throttle body 4 remote from the nozzle and continues in the holding body 2. In the leakage oil chamber 32 there is always a low fuel pressure via a corresponding connection with a leak oil connection, which corresponds essentially to ambient pressure. Since the high-pressure inlet pipe 25 is sealingly guided in the bore 21, different pressures in the distributor space 23 and in the annular space 27 are possible.

The connection between the annular space 27 and the leakage oil space 32 is controlled by a control valve 8, which comprises a control valve member 30. The control valve member 30 cooperates with a control valve seat 29 which is formed in the throttle body 4. The control valve member 30 has the shape of a magnet armature and is the throttle body 4 facing away in a sleeve extension 130 over. The sleeve extension 130 is in this case sealingly guided on the high pressure inlet pipe 25, so that the control valve member 30 is slidable on the high-pressure inlet pipe 25 and a sufficient seal between the annular space 27 and the leakage oil chamber 32 is ensured. The movement of the control valve member 30 is effected on the one hand by a spring 37, which is arranged under pressure bias in the holding body 2 and which is supported on the nozzle facing away from the end of the sleeve extension 130 and so the control valve member 30 presses against the control valve seat 29. On the other hand, the control valve member 30 can be moved by an actuator 33, which is designed here as an electromagnet 33 and which is arranged in the holding body 2. The electromagnet 33 is thereby pressed by a spring element 35, which is arranged in the holding body 2, in the direction of the throttle body 4, so that the electromagnet 33 is fixed in the stationary holding body 2.

The mode of operation of the injector is as follows: Via the high-pressure inlet pipe 25, fuel which has been compressed to high pressure is conducted into the distributor chamber 23. From there, the pressure continues via the inlet throttle 22 in the control chamber 16, which there causes the same fuel pressure as in the distribution chamber 23. About the inlet channel 20, the pressure is also in the pressure chamber 11 continues, so there is applied injection pressure.

The control valve member 30 is pressed by the spring 37 against the control valve seat 29 and closes the annular space 27 against the leakage oil chamber 32, wherein through the outlet throttle 24 in the annular space 27, the same fuel pressure as in the control chamber 16 prevails.

The electromagnet 33 is not energized at the beginning of the injection. If an injection is to take place, a corresponding current is passed through the electromagnet 33 so that it builds up a magnetic field and attracts the control valve member 30. As a result, the control valve member 30 is lifted from the control valve seat 29 and connects the annular space 27 with the leakage oil chamber 32. Via the outlet throttle 24, the fuel located in the control chamber 16 relaxes, so that the hydraulic force on the valve seat 13 facing away from end face of the nozzle needle 10 is reduced. In this case, the outlet throttle 24 is dimensioned so that more fuel flows through them than flows via the inlet throttle 22. At the same time, the hydraulic force that prevails on the nozzle needle 10 by the fuel pressure in the pressure chamber 11, remains constant, so that overall results in a resultant force on the nozzle needle 10, which is directed away from the valve seat 13 and pushes the nozzle needle 10 from the valve seat 13. The thus released injection openings 12 now eject fuel under high pressure. The injection is stopped again by the currentless switching of the electromagnet 33, so that the spring 37 presses the control valve member 30 back into abutment against the control valve seat 29. Through the closure of the annular space 27, the pressure in the control chamber increases via the inlet throttle 22 16 again, so that the nozzle needle 10 is pressed by the increasing hydraulic force on the front side back into its closed position.

FIG. 2 likewise shows in longitudinal section a further injector according to the invention. This differs from the injector of Figure 1 by the alternative embodiment of the

Throttle body 4. Instead of the throttle body 4, a first throttle body 104 and a second throttle body 204 are provided in this embodiment. In the first throttle body 104, the high-pressure inlet pipe 25 receiving bore 21 is formed, the high-pressure inlet pipe 25 does not open here in a distributor chamber 23, but in a recess 39, which assumes the same function and of the inlet throttle

22 and the inlet channel 20 go out. The outlet throttle 24 'is formed both in the first throttle body 104 and in the second throttle body 204, so that the annular space 27, which is formed in the first throttle body 104, is still connected to the control chamber 16. This arrangement of the inlet and outlet throttles and the recess 39 makes it possible to produce them with less effort and thus lower costs, since in particular the recess 39 is formed directly on the end face of the second throttle body 204.

FIG. 3 shows a further exemplary embodiment of an injector according to the invention. The arrangement of the bore 21 in the throttle body 4 of the inlet throttle 22 and the inlet channel 20 corresponds to the arrangement as in the embodiment shown in Figure 1. However, the outlet throttle 24 has a different orientation here. 1, the outlet throttle 24 "is designed here as a straight bore, in order to bring the fuel from the control chamber 16 to the outlet throttle 24", a recess 39 is provided on the end face of the throttle body 4 'facing the nozzle body 5 ' educated. In this recess 39 'also opens the inlet throttle 22, which emanates from the distributor space 23. This straight training of the outlet throttle 24 "can be easier and thus produce cheaper.

Another difference from the injector of Figure 1 is the formation of the nozzle body 5, which is formed in Figure 3 in the region of the control chamber 16 different from the embodiment of Figure 1. The control chamber 16 is limited here by the wall of the bore 9, wherein in the control chamber 16, a closing spring 14 'is located between the throttle body 4 and the valve seat facing away from the end surface of the nozzle needle 10 is arranged under pressure bias. The nozzle needle 10 is with her Valve seat facing away end portion in the bore 9 sealingly guided, so that a hydraulic separation of the pressure chamber 11 and the control chamber 16 is achieved. The other function of the nozzle needle 10 is identical to the embodiment of Figure 1.

FIG. 4 again shows an overall view of the injector according to FIG. 3. The high-pressure inlet pipe 25 has an extension at its inlet-side end into which a fuel filter 44 is inserted. The fuel filter 44 serves to filter out particles present in the fuel in order to prevent damage in the area of the nozzle needle 10 or of the control valve 8. In order to introduce the compressed fuel into the high-pressure feed pipe 25, a high-pressure connection 42 is provided on the injector, which is connected to the injector body 1 by means of a clamping screw 45.

The holding body 2 is formed in this embodiment as a sleeve which is much simpler constructed than the known from the prior art holding body. The electromagnet is here in the power flow of the clamping nut 7, so is fixed by the tension of the holder body 2 and nozzle body 5 in the injector, without further devices for fixing the electromagnet are necessary.

The leakage oil space 32, which surrounds the high-pressure inlet pipe 25, can be limited in volume. For this purpose, an insert body 46 is introduced into the holding body 2, which consists for example of plastic and in which a leakage oil drain 40 is formed. The discharged via the drainage oil drain 40 fuel is supplied via a drain connection 43, a return system, so that the fuel is ultimately returned to the fuel tank of the vehicle.

The movement of the control valve member 30 is effected by the electromagnet 33, as already stated above. Since no resulting hydraulic force is exerted on the control valve member 30 by the pressure in the annular space 27, this is force-balanced so that even a relatively small magnetic force is sufficient to move the control valve member 30. Therefore, the spring 37 needs only a small force to ensure the functionality of the control valve and can be made correspondingly small.

Alternatively, it can also be provided that instead of an electromagnet, a piezoelectric actuator is used to exert a moving force on the control valve member 30. As described above, the control valve member 30 is pressure balanced, which allows the use of a small piezoelectric actuator, since no large forces are needed. The stroke of the piezoactuator can also be small, since the cross section opened between the control valve member 30 and the control valve seat 29 is sufficiently large even with a very small stroke of the control valve member 30.

Claims

claims

Injector for injecting high-pressure fuel into a combustion chamber of an internal combustion engine with an injector body (1) in which a nozzle needle (10) is longitudinally displaceable, which controls the opening of at least one Emspritzöffhung (12) by their longitudinal displacement and with one

Valve seat (13) cooperates, and with a control chamber (16) which can be filled with fuel at high pressure, wherein at least indirectly by the fuel pressure in the control chamber (16) a closing force in the direction of the valve seat (13) on the nozzle needle (10) and with a control valve (8), via which the control chamber (16) can be connected to a leakage oil space (32), so that the control space (16) can be relieved of pressure, wherein the control valve (8) is a control valve member (30). which is movable by an actuator (33), characterized in that in the injector body (1) a high-pressure inlet pipe (25) is arranged, the compressed fuel to the control chamber (16) passes, wherein the control valve member (30) on the high-pressure inlet pipe ( 25) is slidably mounted.

2. An injector according to claim 1, characterized in that the high-pressure inlet pipe (25) extends centrally in the injector body (1), wherein it is arranged substantially in alignment with the nozzle needle (10).

3. An injector according to claim 1, characterized in that the high pressure inlet pipe (25) formed at its outlet end in a in the injector body (1)

Manifold (23) opens, wherein an inlet throttle (22) is provided, through which the control chamber (16) is connected to the distributor chamber (23), and an inlet channel (20), with which the distributor chamber (23) with the Einspritzöffhungen (12 ) is connectable.

4. An injector according to claim 1 or 3, characterized in that the control valve member (30) has a sleeve extension (130) surrounding the high-pressure inlet pipe (25), so that the control valve member (30) on the high pressure inlet pipe (25) is slidably mounted sealingly ,

5. An injector according to claim 4, characterized in that the control valve member (30) cooperates with a control valve seat (29) surrounding the high-pressure inlet pipe (25), so that the high-pressure inlet pipe (25) surrounding annular space (27), with the control chamber (16) via an outlet throttle (24) is connected by the lifting of the control valve member (30) from the control valve seat (29) with a leakage oil space

(32) of the injector is connectable.

6. Injector according to one of claims 1 to 5, characterized in that the control valve member (30) moving actuator is an electromagnet (33).

7. An injector according to claim 6, characterized in that the electromagnet (33) surrounds the high-pressure inlet pipe (25).

8. An injector according to claim 6 or 7, characterized in that the electromagnet between the holding body (2) and valve body (5) is arranged, wherein the holding body (2) and the valve body (5) by means of a clamping nut (7) are pressed against each other, so that the electromagnet between the valve body (5) and holding body (2) is fixed.