WO2009115353A1

WO2009115353A1 - High-pressure pump

Info

Publication number: WO2009115353A1
Application number: PCT/EP2009/050679
Authority: WO
Inventors: Friedrich Boecking
Original assignee: Robert Bosch Gmbh
Priority date: 2008-03-17
Filing date: 2009-01-22
Publication date: 2009-09-24
Also published as: EP2265811A1; DE102008000710A1; EP2265811B1; CN101978158B; CN101978158A; ATE523685T1

Abstract

A high-pressure pump (1) is used especially as a fuel pump for fuel injection systems in air-compressing, self-igniting internal combustion engines. Said high-pressure pump (1) comprises a first pump subassembly (17), a second pump subassembly (18), and a drive shaft (3). The first pump subassembly (17) is located at least approximately across from the second pump subassembly (18) in relation to the drive shaft (3). At least one cam (9) for driving both the first pump subassembly (17) and the second pump subassembly (18) is provided on the drive shaft (3). Furthermore, spring elements (40, 41) are provided which are connected to a piston (23) of the first pump subassembly (17) by means of a retaining brace (45) and are connected to a piston (23) of the second pump subassembly (18). The spring elements (40, 41) are mounted in a biased manner such that the two pistons (23, 23) return without separate return springs or retracting springs during operation of the high-pressure pump (1).

Description

description

Title High pressure pump

State of the art

The invention relates to a high-pressure pump, in particular a fuel pump for fuel injection systems. Specifically, the invention relates to the field of high pressure pumps for fuel injection systems of air compressing, auto-ignition internal combustion engines.

From DE 10 2005 046 670 Al a high-pressure pump for a fuel injection device of an internal combustion engine is known. The known high-pressure pump has a pump housing, in which a pump element is arranged, which has a driven by a drive shaft in a stroke pump piston, which is guided displaceably in a cylinder bore of a part of the pump housing and limited in this a pump working space. The pump piston is supported on the drive shaft via a hollow-cylindrical ram, wherein the ram is displaceably guided in a bore of a part of the pump housing in the direction of the longitudinal axis of the pump piston. In this case, a return spring is provided, which ensures a contact of the pump piston on the plunger, so that the entire composite of pump piston, plunger and support element is acted upon via a roller to the cam of the drive shaft.

The known from DE 10 2005 046 670 Al high-pressure pump has the disadvantage that the return spring, which must be designed relatively strong, occupies a considerable space in the pump housing. This results in restrictions in the construction of the high-pressure pump.

Disclosure of the invention The high pressure pump according to the invention with the features of claim 1 has the advantage that an optimized design of the high pressure pump, in particular in the region of the pump assembly, is possible. Specifically, a return spring can be saved in the pump assembly, so that constructive freedom are created, for example, allow a more favorable design of the high-pressure pump, whereby the high-pressure pump is suitable for higher pressures and / or may have a higher efficiency.

The measures listed in the dependent claims advantageous refinements of the claim 1 high-pressure pump are possible.

Advantageously, a separate return spring or the like can be omitted in the pump assemblies. As a result, for example, the structural design in the region of the first pump assembly can be carried out with greater freedom. Depending on the application, a more compact design or a design that is suitable for higher pressures can take place.

Advantageously, the spring element is designed as an annular spring element, wherein the annular spring element may surround the drive shaft preferably adjacent to the cam. This allows a reliable power transmission, wherein the opposite arrangement of the pump assemblies is a reliable loading of the respective pistons of the pump assemblies in the direction of the drive shaft with a bias. Thus, a reset of the piston and an indirect concern with the cam of the drive shaft is achieved even at high speeds.

It is advantageous that the first pump assembly has a roller skate that receives a running on the cam of the drive shaft roller and that the skate has a groove-shaped recess in which the spring element is at least partially disposed. It is also advantageous that the spring element has a band-shaped portion and that the band-shaped portion of the spring element is inserted into the groove-shaped recess of the skate. This allows the spring element at the same time prevent the rotation of the skate, so that a reliable alignment of the skate, in particular an orientation of the skate, which allows a coaxial alignment of the roller taken up by the roller with respect to an axis of the drive shaft, is possible. Furthermore, it is advantageous that the roller taken up by the roller skate of the pump assembly is oriented at least substantially coaxially with the axis of the drive shaft and that a starting element is attached to the spring element in the region of the roller, which causes a displacement of the roller in the direction of the axis of the drive shaft limited. In this case, a further starting element may be provided in the opposite direction in order to limit a displacement of the roller in the direction of the axis of the drive shaft on both sides. As a result, a tarnish protection for the spring element and at the same time a certain centering of the roller with respect to the cam can be ensured. Furthermore, unwanted conditions in which the skate and / or the roller are no longer oriented substantially coaxially with the axis of the drive shaft can be avoided. As a result, a high reliability of the high-pressure pump can be achieved.

It is advantageous that the first pump arrangement has a retaining bracket which connects the piston of the first pump arrangement with the spring element. The headband can also be used at least partially in a groove-shaped recess of the skate.

Further, it is advantageous that a further spring element is provided, which is connected on the one hand by means of the retaining bracket with the piston of the first pump assembly and on the other hand at least indirectly with the piston of the second pump assembly, and that the spring element and the further spring element in the direction of an axis of the drive shaft spaced apart on different sides of the cam of the drive shaft are provided. The further spring element can be developed according to the spring element.

Advantageously, the first pump arrangement is closed by a cylinder head, on which a projection projecting into the first pump arrangement is formed, wherein in the projection a cylinder bore is formed and the piston defines a pump working space in the cylinder bore and wherein an outer diameter of the projection is at least substantially is equal to an inner diameter of the bore in a main body of a housing into which the first pump assembly is inserted. Thus, the approach in the cylinder bore may have a relatively large wall thickness, so that high pressures in the pump working space can be reached during operation. Furthermore, a high efficiency of the high pressure pump can be achieved because elastic Deformations of the cylinder head, in particular in the region of the neck, in which the cylinder bore is formed, are reduced.

The second pump assembly may be further developed according to the first pump assembly. This also results in the corresponding advantages for the second pump assembly.

Brief description of the drawings

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 high-pressure pump in an excerpt, axial sectional view according to a first embodiment of the invention.

Fig. 2 is an excerpt section through the high-pressure pump shown in FIG. 1 along the section line designated by Il and

Fig. 3 is an excerpt section through the high-pressure pump shown in Fig. 1 according to a second embodiment of the invention.

Embodiments of the invention

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

The high-pressure pump 1 has a multi-part housing 2. Furthermore, the high-pressure pump 1 has a drive shaft 3 which rotates about its axis 4 during operation. The drive shaft 3 is on the one hand at a bearing point 5 in a base body 6 of the Housing 2 stored. On the other hand, the drive shaft 3 is mounted on a bearing 7 in a connected to the main body 6 flange 8 of the housing 2. The two bearing points 5, 7 are arranged axially spaced from each other with respect to the axis 4.

Between the two bearing points 5, 7, the drive shaft 3 a cam 9, which may also be formed as a multiple cam. The term of the cam 9 also includes embodiments of the drive shaft 3, in which, for example, the cam 9 is formed by an eccentric to the axis 4 formed portion on the drive shaft 3.

The main body 6 of the housing 2 has a first bore 15 and at least one second bore 16, which are arranged with respect to the axis 4 of the drive shaft 3 in mutually opposite radial directions. In the first bore 15 of the base body 6, a first pump assembly 17 is arranged. Further, a second pump assembly 18 is disposed in the second bore 16 of the base body 6. The structure and function of the pump assemblies 17, 18 are described mainly with reference to the first pump assembly 17. The structure of the second pump assembly 18 substantially corresponds to that of the first pump assembly 17.

The first bore 15 is closed by a housing part 19 serving as a cylinder head. Furthermore, the second pump assembly 18 is closed by a likewise serving as a cylinder head housing part 20. The housing part 19 has a projection 21, in which a cylinder bore 22 is configured. In the cylinder bore 22, a piston 23 is arranged, which is displaceably mounted in the cylinder bore 22. The piston 23 defines a pump working space 24 in the cylinder bore 22. The pump working space 24 is connected to a fuel passage 25 in which an inlet valve 26 opening to the pump working space 24 is arranged. Further, the pump working space 24 is connected to a fuel passage 27 in which an exhaust valve 28 is arranged, which mainly has the function of preventing a backflow of fuel from the fuel passage 27 into the pump working space 24. By way of the outlet valve 28 and the fuel channel 27, high-pressure fuel can be conveyed to a fuel distributor strip during operation of the high-pressure pump 1.

In the bore 15 of the main body 6 of the housing 2 is a plunger body 30th arranged, which is guided in the bore 15. The plunger body 30 is preferably made relatively thin-walled. As a result, an outer diameter 31 of the projection 21 can be essentially the same size as an inner diameter 32 of the bore 15. This allows a relatively thick-walled configuration of the projection 21, that is, a wall of the projection 21 around the cylinder bore 22. As a result, a high pressure in the pump chamber 24 can be generated, wherein an elastic expansion of the housing part 19, in particular in the region of the projection 21, is avoided , This also allows high pressure generation efficiency.

The pump assembly 17 has a roller skate 35 which receives a roller 36 running on the cam 9 of the drive shaft 3. The roller 36 is oriented at least substantially coaxially with the axis 4 of the drive shaft 3. The piston 23 is supported by a collar 37 of the piston 23 on the skate 35.

The high-pressure pump 1 has a spring element 40 and a further spring element 41. The spring elements 40, 41 are arranged axially spaced relative to each other with respect to the axis 4 of the drive shaft 3. Furthermore, the spring elements 40, 41 are arranged on different sides of the cam 9 of the drive shaft 3. The spring elements 40, 41 thereby surround the drive shaft 3 circumferentially, as is also illustrated with reference to FIG. 3.

Via the spring elements 40, 41, the piston 23 of the first pump assembly 17 is connected to a piston 23 'of the second pump assembly 18. The spring elements 40, 41 are on the one hand indirectly connected to the piston 23 and on the other hand indirectly connected to the piston 23 '. The connection of the piston 23 with the spring elements 40, 41 is further described in detail below. The connection of the piston 23 'with the spring elements 40, 41 results in a corresponding manner.

The first pump assembly 17 has a retaining clip 45, which surrounds the piston 23 above the collar 37, that is to say radially outward viewed from the axis 4. The retaining clip 45 can thereby hold the piston 23 in abutment with the roller skate 35 with respect to rotational forces occurring during operation. The retaining clip 45 is connected to the spring elements 40, 41, which in turn are connected to the piston 23 '. In this case, the spring elements 40, 41 are under a certain bias, so that the headband 45 presses the collar 37 of the piston 23 against the skate 35, which is supported on the roller 36 on the cam 9. Thereby, the piston 23, the Roller skate 35, the roller 36 and the cam 9 are held in abutment with each other.

The first pump assembly 17 also has start-up elements 46, 47, wherein a pin-shaped projection 46 'of the starting element 46, the spring element 40 connects to the headband 45, while a pin-shaped projection 47' of the starting element 47 connects the headband 45 with the other spring element 41. The start-up elements 46, 47 thereby limit a coaxial displaceability of the roller 36, so that within certain limits a centering of the roller 36 with respect to the running surface of the cam 9 is achieved. As a result, a tilting or pivoting, that is, a non-coaxial operation, the roller 36 can be avoided relative to the axis 4 or at least limited in extent, so that a reliable operation of the high pressure pump 1 is ensured.

The cam 9 serves both to drive the first pump assembly 17 and the second pump assembly 18. The spring elements 40, 41, the respective elements of the pump assemblies 17, 18 are held together, so that a reliable operation of the high-pressure pump 1 is possible, with separate return springs for the pistons 23, 23 'of the pump assemblies 17, 18 can each be saved. This allows, inter alia, the relatively thick-walled design of the projection 21 to the cylinder bore 22 of the first pump assembly 17 and a corresponding configuration in the second pump assembly 18. Thus, there is a high efficiency of the high-pressure pump 1 and / or the possibility of fuel under high pressure to a To promote common rail or the like.

FIG. 2 shows an excerpted section through the high-pressure pump 1 shown in FIG. 1 along the section line designated by II in accordance with the embodiment of the first exemplary embodiment of the invention. The headband 45 is designed band-shaped and inserted into a groove-shaped recess 48 in the skate 35. In this case, the spring elements 40, 41 may be at least partially inserted into the groove-shaped recess 48 of the skate 35. By inserting the retaining clip 45 and optionally the spring elements 40, 41 in the groove-shaped recess 48 is a rotation of the skate 35 with respect to a desired position in which the roller 36 is guided coaxially with the axis 4 of the drive shaft 3, prevented. Thus, a coaxial movement of the roller 36 is achieved to the drive shaft 3. Thus, a high reliability of the high-pressure pump 1 can be ensured.

FIG. 3 shows an excerpted section through a high-pressure pump 1 along the in FIG Fig. 1 with III designated cutting line according to a second embodiment of the invention. In this case, the headband 45 is shown cut back at the height of an axis 49 of the piston 23 to allow the view of the spring element 40, the groove-shaped recess 48 and the skate 35. The spring element 40 has a band-shaped portion 49. The band-shaped portion 49 has a circular opening 50, through which the pin-shaped projection 46 'of the starting element 46 extends. The pin-shaped projection 46 'of the starting element 46 also extends through a corresponding opening in the retaining clip 45, so that the spring element 40 is reliably connected at its band-shaped portion 49 to the retaining clip 45. Further, the band-shaped portion 49 of the spring element 40 is partially inserted into the groove-shaped recess 48 of the skate 35, so that a rotation of the skate 35 is prevented from its desired position.

The spring element 40 may surround the drive shaft 3 outside the region of the cam 9 or else be arranged within the region of the cam 9, so that the spring element surrounds the cam 9 of the drive shaft 3 in a circumferential manner. The spring element 40 is preferably mounted biased, so that the spring element 40 biases the piston 23 in the direction of the drive shaft 3. This can account for a separate return spring, in particular in the region of the projection 21 of the housing part 19 serving as a cylinder head. The spring element 40 is designed as an annular spring element 40, so that a uniform force transmission between the first pump assembly 17 and the second pump assembly 18 for returning the piston 23, 23 'is possible in dependence on the respective operating position. In a high-pressure pump 1 designed according to the exemplary embodiments of the invention, the pistons 23, 23 'are connected to one another via at least one spring element 40 so that restoring or return springs in the pump assemblies 17, 18 can be saved. The space saved with respect to a design with return or return springs can be used to reinforce the projection 21 of the cylinder head housing part 19 in the region of the bore 15, which serves as a guide for the plunger body 30, so that an expansion of the as a cylinder head serving housing part 19 is reduced under high pressure.

Furthermore, the spring element 40 runs in the region of the roller skate 35 in a groove-shaped recess 48, so that a rotation of the roller skate 35 is prevented.

The spring element 40 may additionally in the region of the roller 36 a tarnish protection assume a starting element 46, which is also the connecting piece for the spring element 40 with the headband 45.

Special advantages of the high-pressure pump 1 are thus a significantly reinforced, given by the housing part 19 cylinder head and the guaranteed rotation. The reinforced cylinder head allows an optionally significant increase in the efficiency of the high pressure pump. 1

The invention is not limited to the described embodiments.

Claims

claims

A high-pressure pump (1), in particular a fuel pump for fuel injection systems of air-compressing, self-igniting internal combustion engines, with a first pump assembly (17), at least one second pump assembly (18) and a drive shaft (3), wherein the first pump assembly (17) with respect Drive shaft (3) at least approximately opposite to the second pump assembly (18) is arranged, wherein the drive shaft (3) has at least one cam (9), which serves for driving the first pump assembly (17) and the second pump assembly (18), and wherein at least one spring element (40) is provided which is connected on the one hand at least indirectly with a piston (23) of the first pump assembly (17) and on the other hand at least indirectly with a piston (23 ') of the second pump assembly (18).

2. High-pressure pump according to claim 1, characterized in that the spring element (40) is designed as an annular spring element (40).

3. High-pressure pump according to claim 2, characterized in that the annular spring element (40) surrounds the drive shaft (3).

4. High-pressure pump according to one of claims 1 to 3, characterized in that the first pump assembly (17) has a roller skate (35) which receives a on the cam (9) of the drive shaft (3) running roller (36), and that the roller skate (35) has a groove-shaped recess (48) in which the spring element (40) is at least partially arranged.

5. High-pressure pump according to claim 4, characterized in that the spring element (40) has a band-shaped portion (49) and that the band-shaped portion (49) of the spring element (40) at least partially into the groove-shaped recess (48) of the roller skate (35). is inserted.

6. High-pressure pump according to claim 4 or 5, characterized in that the roller (36) at least substantially coaxially to an axis (4) of the drive shaft (3) is oriented and that on the spring element (40) in the region of the roller (36) at least one starting element (46, 47) is fixed, which is a displacement of the Roller (36) in the direction of the axis (4) of the drive shaft (3) limited.

7. High-pressure pump according to one of claims 1 to 6, characterized in that the first pump arrangement (17) has a retaining bracket (45) which connects the piston (23) of the first pump assembly (17) with the spring element (40).

8. High-pressure pump according to claim 7, characterized in that a further spring element (41) is provided, on the one hand by means of the holding bracket (45) with the piston (23) of the first pump assembly (17) and on the other hand at least indirectly with the piston (23 '. ) of the second pump assembly (18) is connected, and that the spring element (40) and the further spring element (41) in the direction of an axis (4) of the drive shaft (3) spaced from each other on different sides of the cam (9) of the drive shaft (3 ) are provided.

9. High-pressure pump according to one of claims 1 to 8, characterized in that the first pump assembly (17) by a cylinder head (19) is closed, on which in the first pump assembly (17) projecting lug (21) is formed that in a bore (22) is formed in the projection (21), wherein the piston (23) delimits a pump working space (24) in the cylinder bore (22), and that an outer diameter (31) of the projection (21) is substantially equal to an inner diameter ( 32) of a bore (15) in a base body (6) of a housing (2) into which the first pump assembly (17) is inserted.

10. High-pressure pump according to claim 9, characterized in that the spring element (40) biases the piston (23) in the direction of the drive shaft (3) and that in the region of the projection (21) of the cylinder head (19) no separate return spring is provided.