WO2010145862A2

WO2010145862A2 - Fuel pump

Info

Publication number: WO2010145862A2
Application number: PCT/EP2010/055020
Authority: WO
Inventors: Josef Frank; Friedrich Boecking; Klaus Ortner; Matthias Greiner
Original assignee: Robert Bosch Gmbh
Priority date: 2009-06-16
Filing date: 2010-04-16
Publication date: 2010-12-23
Also published as: CN102498297A; EP2443344A2; DE102009026964A1; WO2010145862A3

Abstract

The invention relates to a fuel pump (1), which in particular serves as a pump arrangement for fuel injection systems of air-compressing, self-igniting internal combustion engines, comprising at least one housing part (3), a first toothed wheel (15) and a second toothed wheel (16). The toothed wheels (15, 16) are arranged in the housing part (3). Furthermore, the toothed wheels (15, 16) intermesh in order to form a gear pump (17). The invention further relates to an inlet or return (35, 36) for the gear pump (17), which is provided in the housing part (3).

Description

description

Title fuel pump

State of the art

The invention relates to a fuel pump, in particular a pump arrangement with a gear pump. Specifically, the invention relates to the field of fuel injection systems of air compressing, self-igniting internal combustion engines.

From DE 197 36 160 A1 a pump arrangement for high-pressure fuel supply in fuel injection systems of internal combustion engines is known. The known pump arrangement is used in particular for a common rail injection system. The known pump arrangement has a radial piston pump with a drive shaft mounted in a pump housing, which is formed eccentrically or has cam-like elevations in the circumferential direction. Furthermore, several, with respect to the drive shaft radially arranged in a respective cylinder chamber piston are provided, which are reciprocated when turning the drive shaft in the cylinder chamber and forth. In addition, a low pressure pump upstream of the radial piston pump is provided. In order to achieve a compact design of the pump assembly and to reduce the risk of the occurrence of leakage points, the low-pressure pump is provided on or in the pump housing of the radial piston pump on the side facing away from the drive side and driven by the drive shaft of the radial piston pump. Here, a coupling is interposed between the drive shaft of the radial piston pump and a shaft of the low-pressure pump. The housing of the low-pressure pump is mounted on the pump housing of the radial piston pump via a centering device. Furthermore, a projecting in the direction of the housing of the low-pressure pump Zentrierflansch is provided on the pump housing of the radial piston pump, with which the housing of the low-pressure pump is positioned. To guide fuel to the low pressure pump, a channel is led to a suction chamber of the low pressure pump, which has a passage in the pump housing of the radial piston pump communicated. From the channel in the pump housing of the radial piston pump, the fuel is fed to the suction side of the low-pressure pump.

The known from DE 197 36 160 A1 pump assembly has the disadvantage that the design is relatively expensive. Specifically, the low-pressure pump must be reliably connected to the radial piston pump, with a reliable sealing effect in several places is required to ensure reliable operation.

Disclosure of the invention

The fuel pump according to the invention with the features of claim 1 has the advantage that the structure of the fuel pump is simplified. Specifically, a space of the fuel pump can be optimized. Advantageous further developments of the fuel pump specified in claim 1 are possible due to the measures listed in the subclaims.

It is advantageous that both an inlet and a return are provided on the housing part, that the inlet is at least partially configured by an inlet channel formed in the housing part and that the return is at least sectionally configured by a formed in the housing part return channel. Thereby, the inlet and the return can be integrated into the housing part in which the gear pump is provided. As a result, a compact embodiment of the fuel pump is possible. Specifically, an additional component that serves to accommodate a low-pressure circuit can be saved.

It is advantageous here, too, that the inlet channel with the return channel via an inserted into the housing part overflow valve and / or via an inserted into the housing part by-pass valve are interconnected. Thus, the overflow valve and the bypass valve in the housing part in which the gear pump is arranged, can be integrated.

Advantageously, the housing part is closed with an outer lid. The housing part can accommodate both the gear pump and the entire low-pressure circuit. In particular, the gear pump in the area of the toothed wheels can be closed by the outer lid. It is advantageous that the housing part receives a low-pressure unit, that a further housing part is provided which receives a high-pressure unit, and that the gear pump can be driven by a drive shaft mounted in the further housing part. The housing part of the low pressure unit can be connected directly to the housing part of the high pressure unit. A lid or the like, which may be provided between the housing part of the low pressure unit and the housing part of the high pressure unit, can be omitted here. As a result, a compact embodiment of the fuel pump is possible. Specifically, an axial space of the fuel pump can be shortened.

It is also advantageous here for the housing part of the low-pressure unit to have a recess on a side facing the housing part of the high-pressure unit, which at least partially accommodates a coupling part of a coupling provided between the drive shaft and the gear pump. As a result, expansion of the fuel pump in the axial direction can be further shortened. It is also advantageous that the coupling part has an outer side and that the coupling part is mounted on its outer side in the recess of the housing part of the low pressure unit. This allows the design of the fuel pump, in particular the housing parts of the fuel pump, simplified and thus optimized.

It is also possible, however, that the housing part receives both a high pressure unit and the gear pump. As a result, the gear pump can be integrated directly into the housing part of the high-pressure unit. Specifically, in this case, the low pressure circuit can be integrated into the housing part of the high pressure unit, resulting in a compact design of the fuel pump.

It is advantageous in this case that the housing part is designed as a one-piece housing part. A coupling and / or further components or components can be saved as a result. This makes a cost effective solution possible. Furthermore, a length of the fuel pump can be optimized.

It is advantageous that the housing part is formed of an alloy based on aluminum and silicon. Specifically, it is advantageous that the housing part is formed of a hypereutectic alloy with aluminum and silicon. Such an aluminum-silicon alloy allows the storage of elements of the fuel pump, whereby a nickel plating of the bearing surfaces or the like can be omitted. specially For example, the gears of the gear pump can be supported directly on the material of the alloy of the housing part, so that a nickel plating of the bearing surfaces of the gear pump is not necessary. This simplifies the design of the fuel pump, at the same time a wear and störungsunanfällige configuration is possible.

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

1 shows a fuel pump in an excerpt, axial sectional view according to a first embodiment of the invention.

2 shows a section through the fuel pump shown in Figure 1 along the section line indicated by Il in a schematic representation.

Fig. 3 shows the designated in Fig. 1 with III section of a fuel pump according to a second embodiment of the invention and

Fig. 4 in Fig. 1 labeled III section of a fuel pump according to a third embodiment of the invention.

Fig. 1 shows a fuel pump in a fragmentary, axial sectional view according to a first embodiment. The fuel pump 1 can be configured in particular as a pump arrangement for fuel injection systems of air-compressing, self-igniting internal combustion engines. A preferred use of the fuel pump 1 is for a fuel injection system with a common rail that stores diesel fuel under high pressure. However, the fuel pump 1 according to the invention is also suitable for other applications.

The fuel pump 1 has housing parts 2, 3 which are connected to one another. In this case, one side 4 of the housing part 3 faces one side 5 of the housing part 2. The housing part 3 rests with its side 4 on the side 5 of the housing part 2, wherein a sealing ring for sealing between the housing parts 2, 3 is provided. The housing part 2 has a passage opening 7, in which a drive shaft 8 is arranged at least in sections. Here, a bearing 9 is shown in FIG. 1, by means of which the drive shaft 8 is mounted in the housing 2. The bearing 9 is arranged in the passage opening 7. The passage opening 7 is sealed on the side 5 of the housing part 2 by means of the sealing ring 6 from the environment.

In this embodiment, the fuel pump 1 has a high-pressure unit 10 and a low-pressure unit 11. In this case, the housing part 2 receives the high-pressure unit 10. Furthermore, the housing part 3 receives the low-pressure unit 11. The high-pressure unit 10 may, for example, have a radial or series piston pump, which can be driven by the drive shaft 8. The low-pressure unit 11 comprises, for example, a low-pressure pump described in more detail below, as well as low-pressure-side bores or channels for inlet and / or outlet and optionally one or more valves.

In the housing part 3 of the low pressure unit 1 1 gears 15, 16 are arranged, which mesh with each other to form a gear pump 17. The gear pump 17 is thereby integrated into the low-pressure unit 11. The housing part 3 has a further side 18 facing away from the side 4. The side 18 is an outer side 18 of the housing part 3 of the fuel pump 1. On the side 18 of the housing part 3, a lid 19 is attached, which closes the housing part 3. By the cover 19 in this case the gears 15, 16 of the gear pump 17 are covered. The lid 19 serves as an outer lid 19. Here, between the lid 19 and the housing part 3, a sealing ring 20 is provided to seal the gear pump 17 to the outside.

During operation of the fuel pump 1, the drive shaft 8 rotates about an axis 21. The housing part 3 has a bearing bore 22. In the bearing bore 22 is a hub

23 stored. The hub 23 extends through the bearing bore 22 of the housing part 3. The gear 16 is connected to the hub 23. Further, a bearing pin 24 is provided, on which the gear 15 is mounted. In this embodiment, the bearing pin 24 is configured on the housing part 3. An axis 25 of the hub 23 is at least approximately on the axis 21. Thus, the axes 21, 25 at least approximately coincide.

The hub 23 has a drive shaft 8 facing the head portion 26. Between the hub 23 and the drive shaft 8, a coupling part 27 is arranged, which is rotatably connected to the drive shaft 8. Further, the hub 23 is connected to a coupling part 28 which encloses the hub 23. The coupling part 28 is here arranged next to the side 4 of the housing part 3. The coupling parts 27, 28 form a coupling 29 between the drive shaft 8 and the hub 23. The head portion 26 of the hub 23 is arranged in a recess 30 of the coupling part 27. The coupling 29 allows a certain balance between the drive shaft 8 and the hub 23. For example, an axial offset between the axis 21 of the drive shaft 8 and the axis 25 of the hub 23 can be compensated. In addition, compensation can be made if the axes 21, 25 are not aligned exactly coaxial with each other.

When rotating the drive shaft 8, the drive shaft 8 takes over the clutch 29, the hub 25 with. Thus, the gear 16 and thus also the gear pump 17 is driven by the drive shaft 8 during operation of the fuel pump 1.

The fuel pump 1 of the first embodiment is described below in further detail with reference to FIG. 2.

FIG. 2 shows a schematic section through the fuel pump 1 shown in FIG. 1 along the section line designated by II. The fuel pump 1 has an inlet 35 and a return 36. The inlet 35 and the return 36 are provided for the gear pump 17 and provided on the housing part 3. Via the inlet 35, fuel can be sucked from a tank by the gear pump 17. About the return 36 of the funded by the gear pump 17 fuel from the housing part 3 can be performed. The fuel out of the return 36 may then be directed to the high pressure unit 10 to produce the desired high pressure. The gear pump 17 serves as a low pressure pump 17th

The inlet 35 has an inlet channel 37, which is formed in the housing part 3. Furthermore, the return line 36 has a return channel 38, which is likewise formed in the housing part 3. The inlet channel 35 opens at an orifice point 39 in the gear pump 17. The discharge point 39 thus represents the suction side of the gear pump 17. The fuel pumped by the gear pump 17 reaches an orifice 40 of the return channel 38, so that the discharge point 40, the delivery side of the gear pump 17 represents. The positions of the gears 15, 16 of the gear pump 17 are illustrated in FIG. 2 by broken lines 15 ', 16'. The housing part 3 also has stepped bores 41, 42. The stepped bores 41, 42 each connect the inlet channel 37 with the return channel 38. An overflow valve 43 is arranged in the stepped bore 41. Further, a bypass valve 44 is disposed in the stepped bore 42. Thus, the inlet channel 37 and the return channel 38 are connected to one another via the overflow valve 43 and the other via the bypass valve 44. The overflow valve 43 and the bypass valve 44 can thus be integrated together with the gear pump 17 in the housing part 3 of the low pressure unit 1 1. This results in a compact construction of the fuel pump. 1 In particular, an expansion, that is to say an installation space, of the fuel pump 1 in the axial direction, that is to say along the axis 21 or the axis 25, can be reduced, since additional housing parts can be dispensed with. For example, no additional housing part for receiving the gear pump 17 is required.

FIG. 3 shows the section III of FIG. 1 of a fuel pump 1 according to a second exemplary embodiment. In this embodiment, the housing part 3 of the low pressure unit 1 1 on the housing part 2 of the high pressure unit 10 facing side 4 has a recess 50. The recess 50 is designed cylindrical. Furthermore, the cylindrical recess 50 is aligned with the axis 25. In the recess 50, the coupling part 28 of the coupling 29 is at least substantially arranged in this embodiment. The

Recess 50 thus receives the coupling part 28. The coupling part 28 has an outer side 51. On its outer side 51, the coupling part 28 is mounted in the recess 50 of the housing part 3.

The recess 50 has a depth 52 in which the recess 50 of the

Side 4 of the housing part 3 in the direction of the axis 25 in the housing part 3 extends. To this depth 52, the hub 23 may be arranged closer to the drive shaft 8 in comparison to the first embodiment. Thus, the housing part 2 of the high pressure unit 10 can be shortened by the depth 52 in the axial direction. As a result, the axial length of the fuel pump 1 can be further optimized.

In the described with reference to FIGS. 1 and 2 first embodiment and in the second embodiment described with reference to FIG. 3, the housing part 3 is attached to the housing part 2 and inserted with a collar 53 in the through hole 7 of the housing part 2. As a result, a reliable centering of the bearing bore 22 with respect to the axis 21 of the drive shaft 8 is made possible. However, it is also possible that the housing part 2 and the housing part 3 are designed in one piece. In this case, a housing part 2, 3 is provided, so that the gear pump 17 is integrated in the housing part 2, 3 of the high-pressure unit 10, as is also described with reference to FIG. 4.

Fig. 4 shows the designated in Fig. 1 with III section of a fuel pump 1 according to a third embodiment. In this embodiment, a one-piece housing part 2, 3 is provided instead of a two-part design with the housing part 2 and the housing part 3. In this case, a housing part 2, 3 is thus provided, which is designed as a one-piece housing part 2, 3. As a result, the gear pump 17 is integrated into the housing part 2, 3 of the high-pressure unit 10.

An advantage of this one-piece design of the housing part 2, 3 is that a coupling and / or other components or components can be saved thereby. This makes a cost effective solution possible. Furthermore, an overall length of the fuel pump 1 can be optimized.

The housing part 3 and possibly also the housing part 2 are preferably formed from an alloy based on aluminum and silicon. Especially that

Housing part 3 may be formed of a hypereutectic alloy with aluminum and silicon. As a result, a wear-resistant mounting of the gears 15, 16 in the housing part 3 is possible. Specifically, the gear 15 may be mounted directly on the material of the bearing pin 24 of the housing part 3. Furthermore, the hub 23, which serves as a bearing for the gear 16, directly on the material of the housing part 3, namely in the region of the bearing bore 22, be stored. A nickel coating or the like can thereby be dispensed with.

Thus, cost savings and easier assembly are possible in particular due to the reduced part circumference of the fuel pump 1. Furthermore, a scope of inspection can be reduced and an amount of processing can be reduced. In addition, the coupling of the gear pump 17 may be designed to be robust to the drive shaft 8, whereby the life of the fuel pump 1 increases. Furthermore, interfaces are saved which are required, for example, in the case of a separate external gear pump. As a result, a risk of leakage can be reduced. The invention is not limited to the described embodiments.

Claims

claims

1. Fuel pump (1), in particular pump arrangement for fuel injection systems of air-compressing, self-igniting internal combustion engines, with at least one housing part (3), a first gear (15) and a second gear (16), wherein the first gear (15) and the second gear (16) are arranged in the housing part (3) and mesh with each other to form a gear pump and wherein a supply or return (35, 36) for the gear pump (17) is provided, which is provided on the housing part (3) ,

2. Fuel pump according to claim 1, characterized in that an inlet (35) and a return (36) on the housing part (3) are provided, that the inlet (35) at least partially by a in the housing part (3) formed inlet channel (35). 37) and that the return (36) is configured at least in sections by a return channel (38) formed in the housing part (2).

3. A fuel pump according to claim 2, characterized in that the inlet channel (37) with the return channel (38) via a in the housing part (3) inserted overflow valve (43) and / or in the housing part (3) inserted by-pass valve (44 ) are interconnected.

4. Fuel pump according to one of claims 1 to 3, characterized in that the housing part (3) with an outer lid (19) is closed.

5. Fuel pump according to one of claims 1 to 4, characterized in that the housing part (3) receives a low-pressure unit (1 1) that another

Housing part (2) is provided which receives a high-pressure unit (10), and that the Gear pump (17) by a in the other housing part (2) mounted drive shaft (8) can be driven.

6. Fuel pump according to claim 5, characterized in that the housing part (3) of the low-pressure unit (1 1) on a housing part (2) of the high-pressure unit (10) facing side (4) has a recess (50) which at least partially Coupling part (28) of a between the drive shaft (8) and the gear pump (17) provided for coupling (29) receives.

7. A fuel pump according to claim 6, characterized in that the coupling part (28) has an outer side (51) and that the coupling part (28) on its outer side (51) in the recess (50) of the housing part (3) of the low-pressure unit (1 1) is stored.

8. Fuel pump according to one of claims 1 to 4, characterized in that the housing part (2, 3) receives a high-pressure unit (10) and the gear pump (17).

9. Fuel pump according to claims 8, characterized in that the housing part (2, 3) as a one-piece housing part (2, 3) is configured.

10. B renn fabric pump according to one of claims 1 to 9, characterized in that the housing part (2, 3) is formed of an alloy based on aluminum and silicon.

1 1. A fuel pump according to claim 10, characterized in that the housing part (2, 3) is formed of a hypereutectic alloy with aluminum and silicon.

12. Fuel pump according to claim 10 or 11, characterized in that the gears (15, 16) of the gear pump (17) are mounted on the material of the housing part (3).