JP2003269294A - Hydraulic pressure reducing device for fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure reducing device for a fuel injection system for an internal combustion engine, which is structurally simple and improves an operating characteristic of an internal combustion engine, by improving such a type of the device that a fuel injection system comprises a high pressure fuel pump 1, a low pressure pump 21 and a connecting line 23, the low pressure fuel pump 21 force-feeds fuel from a fuel tank 17 to a suction side 3 of the high pressure fuel pump 1, the connecting line 23 connects a force feed side 25 of the low pressure pump 21 to the suction side 3 of the high pressure fuel pump 1, and the pressure reducing device is arranged on the suction side 3 of the high pressure fuel pump 1. <P>SOLUTION: The pressure reducing device is formed as a hydraulically controlled pressure limiting valve 33 whose control pressure is a pressure acting on the force feed side 25 of the low pressure pump 21. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing device for a fuel injection device of an internal combustion engine, the fuel injection device comprising:
A fuel high-pressure pump, a low-pressure pump and a connecting line are provided, a low-pressure pump is provided for pumping fuel from the fuel tank to the suction side of the fuel high-pressure pump, and a connecting line is for pumping the low-pressure pump. Side is connected to the suction side of the fuel high-pressure pump, and the pressure reducing device is arranged on the suction side of the high-pressure fuel pump.

[0002]

A pressure reducing device of this type is known, for example, from DE-A 1993 6 287. In this decompression device, the electrically switchable adjusting member is controlled to open and close in a timing manner, so that the pressure can be adjusted on the pressure feeding side of the low pressure pump. In the no-current state, the adjusting member is open so that no unacceptably high fuel pressure builds up after the internal combustion engine has stopped in the fuel injector.

[0003]

[Patent Document 1] German Patent Application Publication No. 199
36287 Specification

[0004]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to improve the hydraulic decompression device for a fuel injection valve of the type described at the outset to provide a simple structure and operation of an internal combustion engine. It is to provide something that improves the properties.

[0005]

According to the device of the present invention for solving this problem, the pressure reducing device is formed as a hydraulic pressure control type pressure limiting valve, and the pressure control of the low pressure pump is performed as the control pressure. The pressure acting on the side is used.

[0006]

According to the pressure reducing device of the present invention, the load on the electric control device in the fuel injection device is reduced. This is because the decompression device operates hydraulically. Further, with the pressure reducing device of the present invention, the pressure in the high pressure region of the fuel injection device can be maintained even when the internal combustion engine is in a stopped state, so that the subsequent restart of the internal combustion engine is simplified.

In another embodiment of the invention, the pressure limiting valve comprises a casing provided with a stepped bore, in which the stepped piston is closely guided and the stepped piston The ring surface and the stepped hole define a ring chamber, the ring chamber is loaded with pressure acting on the pumping side of the fuel low-pressure pump, and the stepped piston with the first end face comprises: It is spring-loaded and is pressed against the seal seat against the hydraulic force exerted on the stepped piston from the ring chamber, and by the seal seat, it is between the suction side of the high-pressure fuel pump and the fuel return passage. Can be disconnected.
In this embodiment of the invention, at start-up of the internal combustion engine, and thus in the presence of low pressure on the pumping side of the low-pressure pump, all the fuel pumped from the low-pressure pump is pumped directly to the fuel high-pressure pump and thus the fuel injection. It is guaranteed that the pressure rise in the device is as rapid as possible. Apart from this, it is also ensured that, during operation of the internal combustion engine, unacceptably high pressures do not occur on the pumping side of the low-pressure pump. Such pressures occur, for example, when the fuel line is bent or blocked. In this case, the pressure reducing device is opened, and the connection between the suction side of the fuel high-pressure pump and the fuel return path is released, so that pressure reduction is performed.

If an unacceptable high pressure occurs on the suction side of the fuel high-pressure pump during or after the operation of the internal combustion engine, the stepped piston is opened against the spring force and thus a pressure reduction is permitted on the suction side of the high-pressure pump. As a result, the pressure reduction in the entire high pressure region of the fuel injection device is allowed. This makes it possible to avoid damage to the fuel injection system due to overpressure, which can occur, for example, after coasting or stopping the internal combustion engine, depending on the operating temperature. In this case, the decompression device according to the invention is designed in a simple and space-saving manner and is also inexpensive to manufacture.

In a further embodiment of the invention, the pressure limiting valve comprises a casing provided with a stepped hole, in which the stepped piston is guided, the ring of the stepped piston being provided. The face and the stepped hole define a ring chamber, the ring chamber is loaded with pressure acting on the pumping side of the low pressure pump, and the stepped piston with the first end face is spring loaded. And is pressed against the seal seat against the hydraulic force exerted on the stepped piston from the ring chamber, and the seal seat provides a connection between the suction side of the high-pressure fuel pump and the ring chamber. It can be shut off.

In this embodiment, since no leak amount occurs,
The low pressure pump, which is controlled as needed, has the minimum output. This increases the overall efficiency of the internal combustion engine.
Furthermore, since no fuel return path is provided, the risk of leakage is reduced.

In another embodiment of the invention, the hydraulic connection between the suction side of the high-pressure fuel pump and the ring chamber is formed by a passage in the casing or the stepped piston or a groove in the stepped piston. Therefore, the desired hydraulic connection can be formed in a simple manner.

According to another embodiment of the invention, on the pumping side of the low-pressure pump, the control line branches off from the connecting line and the control line leads to the ring chamber of the pressure limiting valve. ,
And / or the control line is provided with a throttle,
The fuel flowing through the control line is limited.

According to another embodiment of the invention, on the suction side of the fuel high-pressure pump, the pressure-compensating line branches off from the connecting line and is restricted by the sealing seat, the first of the stepped pistons. Since a partial surface of the end face of the is loaded with the pressure in the pressure compensation line, if an unacceptable high pressure occurs on the suction side of the fuel high-pressure pump, the stepped piston is lifted from the sealing seat and thus the pressure reduction. Is obtained.

A restriction may be provided in the pressure compensation line to limit the amount of fuel flowing through the pressure compensation line.

A check valve is arranged in the connecting line downstream of the branch position of the control line and upstream of the branch position of the pressure compensating line, in order to improve the pressure maintenance of the internal combustion engine in the stopped state. Has been done. Furthermore, a fuel filter can be arranged in the connecting line.

In a further advantageous embodiment of the invention, at least one jet pump for filling the baffle chamber in the fuel tank with fuel is filled with the fuel flowing in the fuel return passage.

According to an advantageous embodiment, the pressure limiting valve is provided with a pressure spring, which is at least indirectly supported on the casing at one end and at least at the other end. Since it is indirectly supported by the stepped piston, the opening pressure of the decompression device can be adjusted in a simple manner.

Furthermore, it has been proposed to provide a leakage outlet in the casing of the pressure limiting valve. Particularly advantageously in this regard, the pressure limiting valve is mounted above or inside the fuel tank, so that any leaks that occur are returned directly to the fuel tank.

In an alternative embodiment of the invention, the sealing seat comprises a sealing edge cooperating with the first end face of the stepped piston, or the first end face of the stepped piston is frustoconical. And the sealing seat is likewise frustoconical.

Further advantages and advantageous embodiments of the invention can be understood from the description of the examples below, the drawings and the claims.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail with reference to the illustrated examples.

FIG. 1 is a block diagram showing a first embodiment of the combustion injection device according to the present invention. The high-pressure fuel pump 1 has a suction side 3 and a pressure side 5. On the pressure side,
A common rail 7 and a plurality of injectors 9 are connected to the fuel high-pressure pump 1. A pressure sensor 11 and a pressure adjusting or pressure limiting valve 13 are arranged on the common rail 7. A connection line 15 is guided from the pressure adjusting valve 13 to the suction side of the high-pressure fuel pump 1. Alternatively, the connecting line 15 may communicate with the fuel tank 17. The leakage amount of the high-pressure fuel pump 1 is changed to the tank 1 via the leakage pipe line 19.
It is discharged to 7.

A low-pressure fuel pump 21 is arranged in the tank 17. The low-pressure pump 21 can be formed, for example, as an electric fuel pump that is controlled as needed. The low-pressure pump 21 sucks fuel (not shown) from the fuel tank 17 and pressure-feeds it to the connecting pipe line 23. The connecting line 23 connects the pumping side 25 of the low-pressure pump 21 with the suction side 3 of the fuel high-pressure pump 1. In the connection conduit 23,
A check valve 27 and a fuel filter 29 are arranged. On the upstream side of the check valve 27, a control pipe 31 that branches to a pressure reducing valve 33 as a pressure limiting valve branches. The pressure reducing valve 33 is a casing 35 having a hole 37 as a stepped inner hole.
This hole 37 has a stepped piston 39
Is closely guided. The stepped piston 39 and the casing 35 form a ring-shaped ring chamber 41,
The control pipe 31 communicates with the ring chamber 41. The stepped piston is mounted on the seal seat 45, which is a part of the casing 35, at the position shown in FIG. The seal seat 45 has a circular shape. The seal seat 45 divides the first end surface 43 of the stepped piston 39 into an inner surface 47 as a partial surface thereof and a ring-shaped outer surface 49. The inner surface 47 is loaded with the pressure acting on the suction side 3 via the compensating line 51 branching from the suction side 3 of the high-pressure fuel pump 1.

Between the stepped piston 39 and the casing 35, a pressing spring 53 is provided on the side of the stepped piston 39 opposite to the first end surface 43. Ring room 4
While the hydraulic pressure at 1 (pressing force of fuel) and the hydraulic pressure acting on the inner surface 47 of the first end face 43 are smaller than the pressing force of the pressing spring 53, the pressing spring 53 seals the stepped piston 39. Press 45.

When the internal combustion engine is stopped, the pressure in the high pressure region of the fuel injection device is maintained. This is because the check valve 27 and the pressure reducing valve 33 are closed as soon as there is no pressure on the pressure-feeding side 25 of the low-pressure pump 21. When unacceptable high pressure is generated on the suction side of the fuel high-pressure pump 1 due to expansion due to thermal expansion in the area of the common rail 7, for example, the hydraulic pressure acting on the inner surface 47 exceeds the pressing force of the pressing spring 53. The stepped piston 39 is sized to be lifted from the seal seat 45. At this point, the compensation line 51
Since a hydraulic connection is formed between the fuel recirculation passage 55 and the fuel recirculation passage 55, the high pressure on the suction side 3 can be reduced.

When the internal combustion engine is to be operated, initially the pressure on the pumping side 25 of the low pressure pump is not high enough to lift the stepped piston 39 from the sealing seat 45 via the ring chamber 41, so the low pressure pump All the fuel pumped from 21 is supplied to the fuel high-pressure pump 1 via the check valve 27.
Is pumped to the suction side 3. The stepped pump 39 is also not lifted from the sealing seat 45 via the compensation line 51. In other words, the pressure increase is guaranteed as quickly as possible in the high pressure region of the fuel injection device.

The leak-out path 57 starting from the casing 35 of the pressure-reducing valve 33 allows the escape of any leaks which may occur. Advantageously, the pressure reducing valve 33 is mounted above the tank 17. This is because the leak can return directly to the tank 17 via the leak outlet 57 without additional lines.

FIG. 2 shows an alternative embodiment of the invention. The same components are provided with the same reference numerals and correspond to the configuration described in FIG.

Also in this embodiment, as in the embodiment of FIG.
A leakage lead-out path 57 is provided from the casing 35 of the pressure reducing valve 33.

Unlike the first embodiment, a hydraulic connection is provided between the outer surface 49 of the first end surface 43 of the stepped piston 39 and the ring chamber 41. In the example of FIG.
The hydraulic connection is realized by a passage 59 in the casing 35. In this embodiment, the pressure acting on both the outer surface 49 and the step of the stepped piston (which limits the ring chamber 41) additionally acts in the direction against the spring force of the pressure spring 53. To work.

During the stopped state of the internal combustion engine, the pressure reduction on the suction side 3 of the high-pressure fuel pump 1 takes place in the same manner as in the embodiment according to FIG. According to the difference from the embodiment according to FIG. 1, the compensation line 51 is provided with a first throttle 61, which limits the flow of fuel through the compensation line 51. The hydraulic pressure acting on the inner surface 47 causes the pressing spring 53
The stepped piston 39 is lifted from the seal seat 45 and the fuel is passed through the passage 59, the ring chamber 41, the control line 31 and the low pressure pump 21 when it is large enough to overcome the pressure force of Can flow to the tank. This presupposes that a check valve is not provided between the branch point of the control line 31 and the tank.

When the pressure acting on the suction side 3 of the fuel high-pressure pump is within the allowable limit when the internal combustion engine is stopped,
The pressure spring 53 presses the stepped piston 39 against the sealing seat again, so that no pressure reduction is performed via the compensation line 51.
Due to the check valve 27 in the connecting line 23, decompression is also impossible in this route.

In the operating state of the internal combustion engine, a dynamic equilibrium occurs, which causes the stepped piston 39 to be slightly lifted from the sealing seat 45. That is, as soon as the pressure acting on the suction side 3 and the pressure in the control line 31 are of sufficient magnitude to lift the stepped piston 39, the check line 27 and the compensation line immediately bypassing the check valve 27. The hydraulic connection via 51 is opened. The first diaphragm 61 and the second diaphragm 63 arranged in the control line 31.
On the one hand, pressure compensation is possible via, and on the other hand, the pumping quantity of the low-pressure pump 21, which is controlled as required, is kept as small as possible. As a result, the low pressure pump 21
Drive energy demand is minimized, thus increasing the overall efficiency of the internal combustion engine.

Alternatively to passage 59, stepped piston 39 can be provided with a suitable hole (not shown) or stepped piston 39 can be provided with a groove (not shown).

[Brief description of drawings]

FIG. 1 is a block diagram showing a fuel injection device including a first embodiment of a pressure reducing valve according to the present invention.

FIG. 2 is a block diagram showing a fuel injection device including a second embodiment of a pressure reducing valve according to the present invention.

[Explanation of symbols]

1 fuel high pressure pump, 3 suction side, 5 pressure side,
7 Common Rail, 9 Injector, 11 Pressure Sensor, 13 Pressure Limiting Valve, 15 Connection Pipeline, 17
Fuel tank, 19 Leakage line, 21 Low pressure pump, 23 Connection line, 25 Pumping side, 27 Check valve, 29 Fuel filter, 31 Control line, 33
Pressure reducing valve, 35 casing, 37 hole, 39
Stepped piston, 41 ring chamber, 43 end face,
45 seal seat, 47 inner surface, 49 outer surface, 51
Compensation line, 53 pressure spring, 55 fuel return line, 5
7 Leakage outlet, 59 passage, 61 throttle, 63
Aperture

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Christian Clin             Federal Republic of Germany Ostfildern             Kaiser Strasse 5/1 (72) Inventor Jens Wolver             Germany Gerlingen Pappe             Leveque 6 (72) Inventor Ralph Itlinger             Germany Weissachhep             Tinger Strasse 15/1 (72) Inventor Udzibar             Germany Beitichheim             Meisenweg 7/1 (72) Inventor Werner Schneider             Federal Republic of Germany             Mustard Strasse 31 (72) Inventor Marx Amler             Federal Republic of Germany Leonberg-Geve             Rusheim am Schlau Hengrabe             23 (72) Inventor Kirsten Hin             Federal Republic of Germany Giessen Graben             Strasse 58 F term (reference) 3G066 AB02 AD01 BA61 BA67 CB09                       CB11 CB15 CD11 CD29 CE16

Claims (15)

[Claims] 1. A decompression device for a fuel injection device of an internal combustion engine, the fuel injection device comprising a high pressure fuel pump (1).
A low pressure pump (21) and a connecting line (23), the low pressure pump (21) supplying fuel to the fuel tank (1).
7) is provided for pumping to the suction side (3) of the fuel high-pressure pump (1), and the connecting line (23) connects the pressure-feeding side (25) of the low-pressure pump (21) to the fuel high-pressure pump (1). )
Of the type in which the pressure reducing device is connected to the suction side (3) of the fuel pressure pump (1) and the pressure reducing device is disposed on the suction side (3) of the fuel high-pressure pump (1). A valve (33), wherein the pressure acting on the pumping side (25) of the low-pressure pump (21) is used as the control pressure. Decompressor for. 2. The pressure limiting valve (33) has a stepped hole (3).
7) provided with a casing (35) in which a stepped piston (39) is guided in the stepped hole (37), the ring surface of the stepped piston (39) and the stepped hole. (37) separates the ring chamber (41),
The ring chamber (41) is loaded with the pressure acting on the pumping side (25) of the low pressure pump (21) and the stepped piston (39) with the first end face (43) is spring loaded. The seal seat (45) against the hydraulic pressure exerted from the ring chamber (41) on the stepped piston (39).
Is pressed by the seal seat (45) and the suction side (3) of the fuel high-pressure pump (1) and the fuel recirculation path (55).
The decompression device according to claim 1, wherein the connection between the decompression device and the device can be cut off. 3. The pressure limiting valve (33) has a stepped hole (3).
7) provided with a casing (35) in which a stepped piston (39) is guided in the stepped hole (37), the ring surface of the stepped piston (39) and the stepped hole. (37) separates the ring chamber (41),
The ring chamber (41) is loaded with the pressure acting on the pumping side (25) of the low pressure pump (21) and the stepped piston (39) with the first end face (43) is spring loaded. The seal seat (45) against the hydraulic pressure exerted from the ring chamber (41) on the stepped piston (39).
2. The decompression device according to claim 1, wherein the depressurization device is pressed against the valve, and the seal seat (45) can interrupt the connection between the suction side (3) of the high-pressure fuel pump (1) and the ring chamber (41). . 4. A hydraulic connection between the suction side (3) of the high-pressure fuel pump (1) and the ring chamber (41) is provided with a passage (59) in the casing (35) or stepped piston (39). Or a pressure reducing device according to claim 3, formed by a groove provided in the stepped piston (39). 5. The pressure side (25) of the low pressure pump (21).
The control line (31) branches off from the connecting line (23), and the control line (31) leads to the ring chamber (41) of the pressure limiting valve (33). The decompression device according to any one of 1 to 4. 6. The decompression device according to claim 5, wherein the control line (31) is provided with a throttle (63). 7. A suction side (3) of a high-pressure fuel pump (1).
A pressure compensating line (51) diverges from the connecting line and is restricted by the sealing seat (45), a partial surface (47) of the first end face (43) of the stepped piston (39).
The pressure reducing device according to any one of claims 1 to 6, wherein is loaded with the pressure in the pressure compensation line (51). 8. A throttle (61) in the pressure compensation line (51).
The pressure reducing device according to claim 7, wherein the pressure reducing device is provided. 9. Downstream of the branch position of the control line (31) and upstream of the branch position of the pressure compensation line (51).
A check valve (27) is arranged in the connecting line (23),
The decompression device according to any one of claims 3 to 8. 10. The fuel filter (2) in the connecting line (23).
9. The decompression device according to any one of claims 1 to 9, in which 9) is arranged. 11. The fuel flowing in the fuel return channel (55) is adapted to fill at least one jet pump for filling the baffle chamber of the fuel tank (17) with fuel. 11. The decompression device according to any one of 1 to 10. 12. A pressure spring (5) is attached to the pressure limiting valve (33).
3) is provided, the pressure spring (53) being at least indirectly supported on the casing (35) at one end and at least indirectly at the other end by a stepped piston (39). ) Supported by).
The pressure reducing device according to claim 1. 13. A casing (3) for a pressure limiting valve (33).
5. Leakage outlet (57) is provided in 5).
13. The decompression device according to any one of 1 to 12. 14. A seal seat (45) according to any one of claims 2 to 13, wherein the seal seat (45) comprises a sealing edge cooperating with the first end face (43) of the stepped piston (39). Decompression device. 15. The stepped piston (39) has a first end surface (43) which is frustoconical in shape and which has a sealing seat (4).
15. The decompression device according to any one of claims 2 to 14, wherein 5) is likewise frustoconical.