JP2003222062A - Pump element for fuel injection system and high pressure fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pump element for a high pressure fuel pump and a high pressure fuel pump easily formed and surely preventing disadvantageous steam foam from forming. <P>SOLUTION: A first ring passage 41 is formed between a cylinder peripheral wall 43 and a casing 3 of a piston pump 1 in order to cool the pump element 5. <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 high-pressure fuel pump for forming a high-pressure fuel in a fuel injection mechanism (fuel injection system or fuel injection device) of an internal combustion engine. And a high-pressure fuel pump of the type defined in the preamble of claim 8 for a fuel injection device of an internal combustion engine.

[0002]

2. Description of the Related Art As is well known, in a high-pressure fuel pump, particularly in a high-pressure fuel pump for a gasoline direct-injection internal combustion engine, a high temperature is generated during operation and vapor bubbles are locally generated. . Such vapor bubbles are unfavorable, that is, first of all, the vapor bubbles in the discharge chamber of the pump element (pump component) have an adverse effect on the discharge characteristics of the high-pressure fuel pump, and also in the area of the piston sliding surface. The generation of steam bubbles will cause the lubricating film to tear, and eventually the piston will seize.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve a pump element and a high-pressure fuel pump for a high-pressure fuel pump so that the pump element and the high-pressure fuel pump can be easily formed and disadvantageous vapor bubble formation. Is to be surely avoided.

[0004]

In order to solve the above problems, in the structure of the present invention, the first ring passage for cooling the pump element is formed between the pump casing of the piston pump and the cylinder peripheral wall. ing.

The first ring passage ensures that the cooling medium, in particular the fuel, in which the cooling medium is conveyed, keeps the temperature of the cylinder bush and thus of the piston shaft below the evaporation temperature of the fuel. The transfer of fuel through the first ring passage can be done by the pre-transfer pump originally present in the fuel injection mechanism, so that cooling the cylinder bush and the piston shaft requires little additional expense. is there.

According to another feature of the invention, a first ring passage is provided in the cylinder peripheral wall, the first ring groove together with the pump casing forming the first ring passage, or A first ring groove is provided in the pump casing and, together with the cylinder peripheral wall, forms a first ring passage for cooling the pump element.

Both of the above embodiments are equally good in terms of cooling power. One or the other embodiment may be used depending on other conditions of the high pressure fuel pump. Of course, the ring passage is partially inside the cylinder bush,
It is also possible to form the ring groove partially in the casing.

A second ring groove is provided in the piston shaft, and the second ring groove, together with the cylinder bore, forms a second ring passage for lubricating and cooling the piston. The lubrication of the piston shaft in the cylinder bore is correspondingly improved. Even through the second ring passage, the fuel conveyed by the front conveying pump flows, which causes cooling and lubrication of the piston. In the second ring passage, approximately 4 of the front carrier pump
The pressure corresponding to the conveying pressure of ~ 6 bar dominates,
As a result, the evaporation temperature of the fuel is also increased, which provides additional safety against the formation of vapor bubbles. As a result, such a cooled and lubricated piston of the pump element is always separated from the cylinder bore by a stable lubricating film, which guarantees a very wear and slight running of the piston in the cylinder bore.

In order to solve the above problems, according to another aspect of the present invention, there is provided a pump element for a high pressure fuel pump for forming a high pressure fuel of a fuel injection mechanism of an internal combustion engine, the pump element being arranged in a cylinder hole of a cylinder bush. At least 1
Two pistons, the cylinder bush has a cylinder peripheral wall, and the piston has a piston shaft,
A ring groove is provided which, together with the cylinder bore, forms a second ring passage for lubricating and cooling the piston.

The pump element has the above-mentioned advantages of a pump element with a second ring groove. Only the presence of the second ring groove and the second ring passage,
It has been found to be sufficient to guarantee cooling and lubrication of the piston in all operating conditions and to effectively suppress the formation of vapor bubbles.

In order to further reduce the operating temperature of the cylinder bush and the piston, a first ring groove is provided in the cylinder peripheral wall, and the first ring groove together with the pump casing forms the first ring gap. May be formed for cooling the pump element. By this means, in addition, the previously mentioned advantages of the first ring passage can also be realized in this pump element.

The above problems can also be solved by the structures described in the dependent claims of the present invention. In a high-pressure fuel pump, the above-mentioned advantages of the pump element according to the invention are obtained, allowing a trouble-free and low wear operation of the high-pressure fuel pump.

In another configuration of the high-pressure fuel pump according to the invention, a first hydraulic connection is provided in the pump casing between the fuel supply and the first ring passage and / or the second ring passage. It is provided in. Due to the first hydraulic connection, the first ring passage and / or the second ring passage is flowed in a simple manner by the fuel delivered to the high-pressure fuel pump by the front delivery pump, whereby , The desired cooling and lubrication of the cylinder bushing and piston occurs.

In order to avoid pressure shocks on the suction side of the high-pressure fuel pump, a pressure damper is provided according to the invention, the pressure damper occurring in the first hydraulic connection. Try to buffer pressure shock.

A quantity control valve may be provided for adjusting and controlling the delivery of the piston pump according to the invention, which discharges the discharge control quantity into the first hydraulic connection. You can The pressure shock absorber also damps the pressure shock generated by the discharge control amount on the suction side of the high-pressure fuel pump.

Further complementing the present invention, a second hydraulic connection is provided in the pump casing for the first ring passage and / or
Alternatively, a throttle may be provided between the second ring passage and the fuel outlet, and a throttle may be provided between the fuel outlet and the first ring passage and / or the second ring passage. Makes it possible to easily discharge the fuel carried by the front carrier pump into the first and / or the second ring passage, and through the throttle and through the first and / or the second ring passage. The amount of fuel flowing through is adjusted as necessary.

The high-pressure fuel pump according to the invention is particularly suitable for use in internal combustion engines operating on the Otto principle, in particular gasoline direct injection internal combustion engines.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS In the sole drawing, an embodiment of a high-pressure fuel pump 1 according to the invention is shown in section. A pump element 5 and a pressure damper 7 are inserted in the pump casing 3 of the high-pressure fuel pump 1. The pump element 5 comprises a cylinder bushing 9 and a piston 11, which piston comprises a piston shaft 13. The piston shaft 13 of the piston 11 is guided in the cylinder hole 15 of the cylinder bush 9.

The first end 17 of the piston 11 limits or defines the discharge chamber 19 of the pump element 5. The discharge chamber 19 is hydraulically connected to the fuel supply unit 23 via an inlet valve 21. From the fuel supply unit 23 to the inlet valve 2
The path of the fuel into the discharge chamber 19 via 1 is indicated by the arrow 25. A pump (feed pump or low pressure pump) connected to the upstream side of the one not shown is
Fuel is supplied from a fuel tank (also not shown) to the fuel supply unit 2
3 is discharged (supplied). The discharge pressure of the pump is generally 4
Bar to 6 bar.

Fuel flows from the discharge chamber 19 through the outlet valve 27 to the high pressure side 29 of the high pressure fuel pump 1. High voltage side 29 is 1
It is hydraulically connected to one or more injection nozzles (not shown). When the piston 11 moves downward from the inlet valve 21 and the volume of the discharge chamber 19 is increased, the inlet valve 21 is opened. The piston 11 changes the direction of movement,
When the volume of the discharge chamber 19 is reduced again, the inlet valve 21 is closed.

When the pressure in the discharge chamber 19 becomes higher than the pressure on the high pressure side 29 of the high pressure fuel pump 1, the outlet valve 27 opens. The required oscillatory movement (reciprocating movement) of the piston 11 in the cylinder bore 15 is generated by a drive portion (not shown), and the drive portion acts on the second end 31 of the piston 11. . The drive may be a camshaft, an eccentric shaft or the like in the cylinder head of an internal combustion engine. A compression spring 33 is clamped between the second end 31 of the piston and the cylinder bush 9 in order to ensure that the piston 11 follows the drive, for example the cam of the camshaft. A compression spring 33 acts to keep the second end 31 of the piston 11 in constant contact with the eccentric section of the drive or with the cam.

The discharge quantity of the high-pressure fuel pump according to the present invention is adjusted by the metering control valve 35. Metering control valve 3
5 is hydraulically connected to the discharge chamber 19 via the connection hole 37. As soon as the piston has sufficiently discharged the fuel from the discharge chamber 19 to the high pressure side, the control valve 35 is opened and, as a result,
The fuel subsequently discharged by the piston 11 is no longer sent to the high-pressure side 29, but is led to the pressure damper 7 via the connection hole 37 and the first liquid connection 39.

The first liquid connecting portion 39 has various sections, which are designated by 39a, 39b, 39c and 39d.
It is represented by. The discharge control amount from the discharge chamber 19 is determined by the connection hole
7 and the first liquid connection section 39b to the pressure damper 7. The fuel supply 23 is likewise connected to the pressure damper 7 via the section 39 a of the first liquid connection 39. The fuel supply unit 2 of the high-pressure fuel pump 1 is driven by the upstream pump via the section 39c of the first liquid connection unit 39.
The fuel supplied into the inside 3 flows into the first ring passage 41 between the cylinder peripheral wall 43 of the cylinder bush 9 and the receiving hole 45 of the pump casing 3.

In the illustrated embodiment, the first ring passage 41
Is a step provided on the cylinder peripheral wall 43 and the receiving hole 4
5 is formed by the step portion. In another embodiment, the first ring passage may be formed by a ring groove (not shown) provided in the cylinder bush and / or a ring groove (not shown) provided in the receiving hole 45. An O-ring 47 is arranged between the cylinder bush 9 and the pump casing 3 in order to prevent leakage from the first ring passage 41. The fuel continuously flows into the first ring passage 41 from the fuel supply unit 23 via the first liquid connection units 39a, 39b and 39c.
As a result, the cylinder bush 9 is cooled, and as a result, the piston 11 is also cooled. Therefore, the tendency of vapor bubble formation is reduced, which is especially true for the piston shaft 13
Is important in the area of the sliding surface between the cylinder bore 15 and the cylinder bore 15.
The fuel flows from the first ring passage 41 to the fuel outflow portion 51 through the throttle, and the fuel outflow portion may be connected to, for example, a tank (not shown).

To further improve the cooling and lubrication of the piston 11, the piston shaft 13 is provided with a second ring passage 5
3 is provided, and the ring passage is the piston shaft 13
Is formed by the second ring groove 55. The second ring passage 5 via the section 39d of the first liquid connection.
3 is loaded with fuel. As a result, a remarkably stable lubricating film is formed between the piston shaft 13 and the cylinder hole 15. A positive pressure of 4 bar to 6 bar acts on the second ring passage 53 and the first ring passage 41 based on the discharge pressure of about 4 bar to 6 bar of the pump (not shown) arranged on the upstream side. However, this further suppresses the generation of vapor bubbles. As can be seen, the first ring passage 41 alone or the second ring passage 53 alone achieves a clear improvement in service life and wear of the pump element 5. By the combination of both means,
The service life and operating characteristics of the high-pressure fuel pump 1 according to the invention are further improved.

In the drawing, a leakage chamber 57 is provided below the second ring passage 53, and the leakage chamber guides the leakage amount to the fuel outflow portion 51 via the second connection hole 59. ing. A second liquid connecting portion 61 is provided between the throttle 49 and the fuel outflow portion 51, and a second liquid connecting portion 61 is provided at the fluid connecting portion.
Connection hole 59 is open. Due to the sizing of the throttle 49, the first ring passage 4 is passed through the first liquid connecting portion 39.
The fuel flow entering 1 is regulated. The second ring passage 53 is loaded with a predetermined pressure, which helps stabilize the lubricating film.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a high pressure fuel pump according to the present invention.

[Explanation of symbols] 1 high-pressure fuel pump, 3 pump casing, 5
Pump element, 7 Pressure damper, 9 Cylinder bush, 11 Piston, 13 Piston shaft, 15 Cylinder hole, 17 1st end part, 19
Discharge chamber, 21 inlet valve, 23 fuel supply section, 2
5 arrow, 27 outlet valve, 29 high pressure side, 31
Second end, 33 compression spring, 35 metering control valve,
37 connection hole, 39 first liquid connection portion, 39a,
39b, 39c, 39d division, 41 1st ring passage, 43 cylinder peripheral wall, 45 receiving hole, 47
O-ring, 49 throttle, 51 fuel outlet, 53
Second ring passage, 55 Second ring groove, 57
Leakage chamber, 59 Second connection hole, 61 Second liquid connection part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Peter Lopertz             Federal Republic of Germany             Primerveke 7 (72) Inventor Ziament Flow             Federal Republic of Germany             Thraller Strasse 109 (72) Inventor Klemens Scheevtsik             Federal Republic of Germany Eningensta             -Renweg 1/1 F term (reference) 3G066 AA02 BA37 BA41 CA01S                       CA08 CA20Z CA39S CD07                       CD23 CE02

Claims (13)

[Claims] 1. A pump element for a high-pressure fuel pump (1) for forming a high-pressure fuel of a fuel injection mechanism of an internal combustion engine, comprising a cylinder hole (15) of a cylinder bush (9).
A cylinder bush (9) having at least one piston (11) arranged therein.
3) in which the piston (11) has a piston shaft (13), between the pump casing (3) of the piston pump (1) and the cylinder peripheral wall (43), Pump element for a fuel injection mechanism, characterized in that a ring passage (41) for cooling the pump element (5) is formed. 2. A pump element according to claim 1, wherein the cylinder peripheral wall (43) and / or the pump casing (3) are provided with a step forming a ring passage (41). 3. A cylinder circumferential wall (43) is provided with a ring groove, which together with the pump casing (3) forms a ring passage (41) for cooling the pump element (5). The pump element according to claim 1, wherein 4. The pump casing (3) is provided with a ring groove, the ring groove together with the cylinder peripheral wall (43),
Ring passage (4) for cooling the pump element (5)
Pump element according to any one of claims 1 to 3, which forms 1). 5. The piston shaft (13) is provided with another ring groove (55), which ring groove (55) together with the cylinder bore (15) for lubrication and cooling of the piston (11). 5. A pump element according to claim 1, wherein the pump element forms another ring passage (53). 6. A pump element for a high-pressure fuel pump (1) for forming a high-pressure fuel of a fuel injection mechanism of an internal combustion engine, the cylinder element (15) of a cylinder bush (9).
A cylinder bush (9) having at least one piston (11) arranged therein.
3) and the piston (11) has a piston shaft (13), the piston shaft (13) is provided with a ring groove (55), and the ring groove (55) is provided. Together with the cylinder bore, the piston (1
Pump element for a fuel injection mechanism, characterized in that it forms a ring passage (53) for lubrication and cooling according to 1). 7. A ring groove is provided in the cylinder peripheral wall (43), which ring groove together with the pump casing (3) of the piston pump (1) is provided for another ring for cooling the pump element (5). Pump element according to claim 5, characterized in that it forms a channel (41). 8. A high pressure fuel pump for a fuel injection system of an internal combustion engine, comprising a pump element received in a pump casing (3), an inlet valve (21) and an outlet valve (27). High-pressure fuel pump for a fuel injector, characterized in that the pump element is a pump element (5) according to any one of claims 1 to 7. 9. A ring passage (41) formed in the pump casing (3) by the fuel supply (23) and the ring passage (41) between the pump casing and the cylinder peripheral wall and / or the ring groove of the piston shaft. 53), the liquid connection part (39a, 39b, 39c, 39d)
9. The high-pressure fuel pump according to claim 8, wherein: 10. The high-pressure fuel pump (1) has a pressure damper (7), which comprises a liquid connection (39).
10. The high-pressure fuel pump according to claim 9, which is adapted to buffer a pressure shock generated in a, 39b, 39c, 39d). 11. The high-pressure fuel pump (1) has a metering control valve (35), so that the metering control valve (35) guides the discharge control quantity to the liquid connection (39b, 39c). The high pressure fuel pump according to claim 9 or 10. 12. A ring passage (41) in the pump casing (3) between the pump casing and the cylinder wall.
And / or another liquid connection (61) is provided between the ring passage (53) formed by the ring groove of the piston shaft and the fuel outlet (51), and the fuel outlet (51). A throttle (49) is provided between the ring passage (41) between the pump casing and the peripheral wall of the cylinder and / or the ring passage (53) formed by the ring groove of the piston shaft. The high-pressure fuel pump according to any one of 11 to 11. 13. The high-pressure fuel pump according to claim 8, wherein the high-pressure fuel pump is adapted to be used in an internal combustion engine which operates on the Otto principle, in particular, a gasoline direct-injection internal combustion engine. Fuel pump.