WO2010072493A1

WO2010072493A1 - High pressure pump

Info

Publication number: WO2010072493A1
Application number: PCT/EP2009/065661
Authority: WO
Inventors: Uwe Nigrin
Original assignee: Continental Automotive Gmbh
Priority date: 2008-12-16
Filing date: 2009-11-23
Publication date: 2010-07-01
Also published as: EP2379871A1; EP2379871B1; DE102008062518B4; DE102008062518A1

Abstract

The invention relates to a high pressure pump (10) for delivering a fluid, having a rotatable drive shaft (16), a pump unit (12) which can be driven by said drive shaft (16) and comprises a cylinder housing (14) having a fluid inlet chamber (30) and a high pressure chamber (21) which can be hydraulically coupled to the fluid inlet chamber (30) and in which an axially movable high pressure piston (20) is arranged that is operatively connected to the drive shaft (16) and can be subjected to high pressure, and a volume flow control valve (40). The volume flow control valve (40) is designed to set the fluid flow into the high pressure pump (10) and is at least partially arranged in the fluid inlet chamber (30).

Description

description

high pressure pump

The invention relates to a high-pressure pump.

Preferably, such a high-pressure pump is used as a feed pump for conveying fluid for a storage injection system for internal combustion engines of motor vehicles.

Storage injection systems for internal combustion engines of motor vehicles, for example in common-rail systems, should be able to provide the necessary volume flow and the required fluid pressure. The high-pressure pump is subject to strong loads in memory injection systems for motor vehicles, in particular mechanical stresses. In particular, large forces must be absorbed by such high-pressure pumps. Thus, both high demands are placed on the materials that make up the components of the high pressure pump, as well as the construction of the high pressure pump.

Since high pressure pumps are exposed to pressures of, for example, up to 2000 bar or more, they must withstand high stresses.

The object of the invention is to provide a high-pressure pump, which allows reliable and precise operation even at high pump pressures and thereby subject to the lowest possible wear. At the same time, the high-pressure pump should be inexpensive to produce. The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by a high-pressure pump for conveying a fluid, having a rotatable drive shaft, a driven by the drive shaft pump unit having a cylinder housing with a fluid inlet chamber and a hydraulically coupled to the fluid inlet chamber high-pressure chamber in which an axially movable, with of the

Drive shaft is operatively connected to the high-pressure piston and which can be acted upon by high pressure, and a volume flow control valve, which is designed to adjust the fluid flow into the high-pressure pump, wherein the volume flow control valve is at least partially disposed in the fluid inlet chamber.

The term fluid is to be understood here in its broader sense, so the fluid can be both a liquid and a gas.

Such a high-pressure pump has the advantage that a direct hydraulic connection between the volume flow control valve and the fluid inlet chamber of the high-pressure pump is possible. Thus, no connection line between the flow control valve and the fluid inlet chamber of the high-pressure pump is required. In particular, a compact design of the high-pressure pump with integrated volume flow control valve can be realized.

In an advantageous embodiment, the fluid inlet chamber is arranged in a substantially hollow cylindrical portion of the cylinder housing, and the hollow cylindrical portion has an outer wall. This allows light a simple arrangement of the flow control valve in the fluid inlet chamber of the high-pressure pump. This makes a simple production concept for the high-pressure pump possible.

In a further preferred embodiment, the high-pressure pump has a connection piece with an inner fluid channel for supplying fluid. The connecting piece has a hollow cylindrical base body with an inner wall which rests in a fluid-tight manner on the outer wall of the hollow cylindrical section, and in the hollow cylindrical portion of the cylinder housing a fluid passage opening is formed, by means of which the fluid channel is hydraulically coupled to the fluid inlet chamber. This has the advantage that only a single common fluid port is required for supplying fluid to the high pressure pump and the flow control valve.

In a further preferred embodiment, an annular groove is formed in the hollow cylindrical base body in the region of the inner wall, and the connecting piece is arranged on the hollow cylindrical portion of the cylinder housing, that the fluid passage opening is hydraulically coupled to the annular groove. This has the advantage that the connecting piece can be aligned in any azimuth angle with respect to the hollow cylindrical portion of the cylinder housing.

It is particularly preferred if the connecting piece is mechanically coupled by means of a snap connection with the hollow cylindrical section of the cylinder housing. This has the advantage that a simple, rapid and secure coupling between the connecting piece and the hollow cylindrical portion of the cylinder housing is possible. In a further preferred embodiment, the connecting piece is formed from a material which comprises a plastic. For a simple and inexpensive design of the connection piece is possible.

In another preferred embodiment, an inlet valve is disposed in the cylinder housing upstream of the high pressure chamber and downstream of the volumetric flow control valve, and the inlet valve is partially disposed within the volumetric flow control valve. This allows a very compact design of the unit consisting of high-pressure pump with integrated flow control valve.

Embodiments of the invention are explained in more detail below with reference to the schematic drawings.

Show it:

1 shows a schematic view of a high-pressure pump in a longitudinal section, and

FIG. 2 shows a schematic view of the high-pressure pump in a cross section along the line II-II 'of FIG. 1.

Elements of the same construction or function are provided across the figures with the same reference numerals.

Figures 1 and 2 show a high-pressure pump 10 with a pump unit 12. The high-pressure pump 10 can be used in particular for high-pressure fuel supply in a storage injection system of an internal combustion engine of a motor vehicle. The high pressure pump 10 has centrally a drive shaft 16 which is in operative connection with a cam ring with cam 18 and is rotatable about a rotation axis D. In this case, the number of conveying and compression strokes over the number of cams 18 can be specified. The number of conveying or compression strokes corresponds to the number of cams. Instead of the cam ring with the cams 18, an eccentric ring and sliding shoes can also be used in conjunction with the drive shaft 16. Likewise, instead of the cam ring with the cams 18, a circular ring and a mushroom piston in conjunction with the drive shaft 16 can be used. Alternatively, the high pressure pump 10 may also be designed as a crank drive pump.

The pump unit 12 essentially consists of a cylinder housing 14 with a longitudinal axis L, a high pressure piston 20, a high pressure chamber 21 arranged in the cylinder housing 14, a spring 26 and a plunger assembly 28.

The cylinder housing 14, the high pressure piston 20, the high pressure chamber 21 and the spring 26 are arranged coaxially with each other. The cylinder housing 14 is formed of a metal, preferably a steel.

The high pressure piston 20 is axially movably mounted in the high pressure chamber 21 and is in operative connection with the drive shaft 16 and the cam 18. The high-pressure piston 20 is held in constant contact with the cams 18 by means of the spring 26, which is preferably designed as a helical compression spring and is preferably supported on the cylinder housing 14 and on the high-pressure piston 20. Thus, a lifting and Wiederauf- meeting of the high-pressure piston 20 can be avoided on the cam 18, which could lead to damage both the cam 18 and the high-pressure piston 20. In order to be able to fill the high-pressure chamber 21 with fluid, the cylinder housing 14 has a high-pressure chamber inlet line 22, in which preferably an inlet valve 23 is arranged. The inlet valve 23 facilitates the filling of the high pressure chamber 21 and prevents the backflow of the fluid from the high pressure chamber inlet line 22 during filling. The cylinder housing 14 further has a high pressure chamber drain line 24 and an outlet valve 25 arranged therein. Via the high-pressure chamber drain line 24, the outlet valve 25 and a high-pressure nozzle 29, the fluid can be ejected from the high-pressure chamber 21 in a flow direction F of the fluid in the direction of a fluid reservoir, not shown.

During a suction stroke, that is to say a downward movement of the high-pressure piston 20 with respect to FIG. 1, fluid, in particular fuel, is conveyed from the high-pressure chamber feed line 22 via the inlet valve 23 into the high-pressure chamber 21, the outlet valve 25 being closed. During a pumping stroke, that is to say a movement of the high-pressure piston 20 directed upward with respect to FIG. 1, the fuel in the high-pressure chamber 21 is compressed or discharged via the outlet valve 25 under high pressure, the inlet valve 23 being closed.

In the cylinder housing 14, a fluid inlet chamber 30 is arranged, which is hydraulically coupled to the high-pressure chamber 21 via the inlet valve 23. The fluid inlet chamber 30 is arranged in the cylinder housing 14 such that a hollow cylindrical portion 32 of the cylinder housing 14 is formed. The hollow cylindrical portion 32 has an outer wall 34. In the hollow cylindrical portion 32 of the cylinder housing 14, one or more fluid passage openings 36 are formed, which, based on the longitudinal axis L of the cylinder housing 14, extending in the radial direction. In the fluid inlet chamber 30, a volume flow control valve 40 is arranged. In the embodiment illustrated here, the volume flow control valve 40 is only partially disposed in the fluid inlet chamber 30. In further embodiments, the volume flow control valve 40 may also be arranged completely in the fluid inlet chamber 30.

The volume flow control valve 40 serves to adjust the fluid flow in the high-pressure pump 10. The volume flow control valve 40 has a valve inlet line 42 and a valve outlet line 44. Centrally in the volume flow control valve 40, a valve stem 46 is formed. Depending on the axial position of the valve stem 46, a fluid flow of the

Valve inlet line 42 to the valve drain line 44 allows his or this be prevented.

The volume flow control valve 40 is fixedly arranged in the hollow cylindrical section 32 of the cylinder housing 14 by means of a screw 48. In further embodiments, instead of the screw 48, the volume flow control valve 40 may also have a latching connection in order to fix the volume flow control valve 40 firmly in the hollow cylindrical section 32 of the cylinder housing 14. Furthermore, additionally or alternatively, connecting elements for fastening the volume flow control valve 40 in the hollow cylindrical portion 32 of the cylinder housing 14 can be used.

By means of one or more sealing elements 50, leakage of fluid from the volume flow control valve 40 to the outside or inadvertent penetration of fluid into the valve drain line 44 can be prevented. Such an arrangement of the volume flow control valve 40 in the fluid inlet chamber 30, a direct hydraulic connection between the flow control valve 40 and the fluid inlet chamber 30 can be achieved. Thus, no connection line between the volume flow control valve 40 and the fluid inlet chamber 30 of the high-pressure pump 10 is required. It can thus be achieved in particular a particularly compact construction of the high-pressure pump 10 with the integrated volume flow control valve 40.

In the embodiment shown here, the inlet valve 23 is partially disposed within the volume flow control valve 40. This makes it possible to achieve a very compact design of the high-pressure pump 10 with an integration of the volume flow control valve 40 and the inlet valve 23 in a construction space of the cylinder housing 14. However, the inlet valve 23 may also be arranged completely outside the volume flow control valve 40.

The high-pressure pump 10 further has a connecting piece 52, with a hollow cylindrical base body 54 and a pipe section 56. The connecting piece 52 is preferably formed from a material which comprises a plastic. Particularly preferably, a connecting piece 52 is completely formed from a plastic.

The hollow cylindrical base body 54 has a continuous fluid channel 58 in the direction of the longitudinal axis L of the cylinder housing 14. The fluid channel 58 of the connecting piece 52 serves to supply fluid to the fluid inlet chamber 30 and thus on to the high-pressure chamber 21 of the high-pressure pump 10. The hollow cylindrical basic body 54 has an inner wall 62, which rests in a fluid-tight manner on the outer wall 34 of the hollow cylindrical portion 32 of the cylinder housing 14. By means of the fluid passage opening 36, the fluid channel 58 is hydraulically coupled to the fluid inlet chamber 30. It can thus be achieved that the connecting piece 52 is designed as the only common fluid connection for the high-pressure chamber 21 of the high-pressure pump 10 and the volume flow control valve 40.

In the hollow cylindrical body 54 of the connecting piece 52, an annular groove 60 is formed, through which a fluid flow from the fluid channel 58 to the valve inlet line 42 of the volume flow control valve 40 regardless of the position of the connecting piece 52 with respect to an azimuth angle ALPHA between the connecting piece 52 and a predetermined reference line (in the embodiment shown here by way of example with respect to a central axis M of the high-pressure nozzle 29) is made possible (Figure 2).

In the embodiment shown here, the connecting piece 52 is coupled by means of a snap connection 64 in the direction of the longitudinal axis L of the cylinder housing 14 with the hollow cylindrical portion 32 of the cylinder housing 14. The snap connection 64 allows a secure coupling between the connecting piece 52 and the hollow cylindrical portion 32 of the cylinder housing 14th

Between the inner wall 62 of the base body 54 and the outer wall 34 of the cylinder housing 14 further sealing elements 66 are arranged, by means of which a fluid leakage between the hollow cylindrical portion 32 of the cylinder housing 14 and the connecting piece 52 can be avoided. Overall, a realization of such a high-pressure pump 10 allows a very compact construction of the pump unit 12, whereby a particularly cost-effective design of the high-pressure pump 10 with few individual parts and a very small space including the volume flow control valve 40 can be achieved.

The mode of operation of the high-pressure pump 10 will be described below:

In the initial state, the high-pressure piston 20 should be in a position in the pump unit 12, in which it has a maximum distance from the drive shaft 16, as shown in Figure 1.

By a rotational movement of the drive shaft 16 about the axis of rotation D of the high pressure piston 20 is moved by means of the cam 18 in the direction of the longitudinal axis L to the drive shaft 16. By the movement of the high pressure piston 20, the high pressure chamber 21 is increased and the fluid is via the fluid channel 58 and the annular groove 60 of the connecting piece 52, the fluid passage opening 36 of the cylinder housing 14, the valve inlet line 42 and the valve drain line 44 of the volume flow control valve 40, and the fluid inlet chamber 30 is guided via the inlet valve 23 designed as a check valve into the high-pressure chamber 21. In this case, the high-pressure chamber 21 is filled with fluid.

As a result of the further rotational movement of the drive shaft 16, the high-pressure piston 20 is moved away from the drive shaft 16 by the cams 18 in the direction of the longitudinal axis L, thereby compressing the fluid located in the high-pressure chamber 21. In this case, pressures of up to 2000 bar in the high pressure chamber 21 may occur. The compressed fluid may be following the Compression stroke via the Hochdruckkammerablaufleitung 24 and the now open exhaust valve 25 are ejected.

If the high-pressure pump 10 is, for example, a high-pressure fuel pump of an injection system of an internal combustion engine, the fuel subjected to high pressure can reach a fluid accumulator designed as a high-pressure fuel accumulator, the so-called common rail.

Reference sign list

10 high pressure pump

12 pump unit 14 cylinder housing

16 drive shaft

18 cams

20 high pressure pistons

21 high pressure chamber 22 high pressure chamber inlet pipe

23 inlet valve

24 high pressure chamber drain line

25 Exhaust valve 26 Spring 28 Plunger assembly

29 high pressure nozzles

30 fluid inlet chamber

32 hollow cylindrical portion of the cylinder housing

34 outer wall of the hollow cylindrical portion 36 fluid passage opening of the cylinder housing

40 volume flow control valve

42 valve inlet line

44 Valve drain line

46 Valve tappet 48 Screw connection

50 sealing element

52 connecting pieces

54 hollow cylindrical basic body of the Anschlussst.

56 Pipe section of connecting piece 58 Fluid channel

60 ring groove

62 inner wall of the body

64 snap connection

66 sealing element F flow direction of the fluid

L longitudinal axis of the cylinder housing

D rotation axis M center axis

Claims

claims

1. High-pressure pump (10) for conveying a fluid, with a rotatable drive shaft (16), - one of the drive shaft (16) drivable pump unit (12) having a cylinder housing (14) with a fluid-entry chamber (30) and with a the fluid entry chamber (30) has a hydraulically couplable high-pressure chamber (21) in which an axially movable high-pressure piston (20) which is in operative connection with the drive shaft (16) is arranged and which can be subjected to high pressure, and a volume flow control valve (40), which is designed to adjust the fluid flow into the high-pressure pump (10), wherein the volume flow control valve (40) is at least partially disposed in the fluid inlet chamber (30).

2. High-pressure pump (10) according to claim 1, wherein the fluid inlet chamber (30) in a substantially hollow cylindrical portion (32) of the cylinder housing (14) is arranged, and the hollow cylindrical portion (32) has an outer wall (34) ,

3. High-pressure pump (10) according to claim 2, wherein the high-pressure pump (10) has a connecting piece (52) with an inner fluid channel (58) for supplying fluid, wherein the connecting piece (52) has a hollow cylindrical basic body (54) with an inner wall (54). 62), the fluid-tight against the outer wall (34) of the hollow cylindrical portion (32) abuts, and in the hollow cylindrical portion (32) of the cylinder housing (14) has a Flu- iddurchtrittsöffnung (36) is formed by the the fluid channel (58) is hydraulically coupled to the fluid entry chamber (30).

4. high-pressure pump (10) according to claim 3, wherein in the hollow cylindrical base body (54) in the region of the inner wall (62) an annular groove (60) is formed, and the connecting piece (52) on the hollow cylindrical portion (32) of the Cylinder housing (14) is arranged, that the fluid passage opening (36) is hydraulically coupled to the annular groove (60).

5. High-pressure pump (10) according to claim 3 or 4, wherein the connecting piece (52) by means of a snap connection

(64) is mechanically coupled to the hollow cylindrical portion (32) of the cylinder housing (14).

6. High-pressure pump (10) according to one of claims 3 to 5, wherein the connecting piece (52) is formed of a material having a plastic.

7. High-pressure pump (10) according to any one of the preceding claims, wherein in the cylinder housing (14) upstream of the high-pressure chamber (21) and downstream of the flow control valve (20), an inlet valve (23) is arranged, and the inlet valve (23) partially within the volume flow control valve (40) is arranged.