DE102008000710A1 - high pressure pump - Google Patents

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

State of the art

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

From the DE 10 2005 046 670 A1 a high pressure pump for a fuel injector 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 from the DE 10 2005 046 670 A1 known 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 the high-pressure pump, in particular in the region of the pump assembly, is possible. Specifically, a return spring be saved in the pump assembly, so that constructive freedom are created, for example, a cheaper configuration allow the high pressure pump, causing the high pressure pump is suitable for higher pressures and / or higher May have efficiency.

By the measures listed in the dependent claims are advantageous developments of specified in claim 1 High pressure pump possible.

In Advantageously, a separate return spring or The like omitted in the pump assemblies. This can, for example the structural design in the area of the first pump assembly be executed with greater freedom. Depending on the application, a more compact design or a design for higher pressures is suitable to take place.

In Advantageously, the spring element is designed as an annular Spring element configured, wherein the annular spring element preferably surround the drive shaft adjacent to the cam can. This allows a reliable power transmission, wherein through the opposite arrangement of the pump assemblies a reliable admission of the respective pistons the pump assemblies in the direction of the drive shaft with a Preload takes place. Thus, a reset is also at high speeds the piston and an indirect concern with the cam of the drive shaft reached.

Advantageous it is that the first pump assembly has a skate, which 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 arranged at least partially. there It is also advantageous that the spring element is a band-shaped Section and that the band-shaped portion of the Spring element in the groove-shaped recess of the skate is inserted. This allows the spring element at the same time the rotation prevent the roller skate, so that a reliable alignment of the Roller skate, in particular an orientation of the skate, the one coaxial alignment of the roll received by the skate in Conditional on an axis of the drive shaft allows is.

Further It is beneficial that the skate of the pump assembly recorded roll at least substantially coaxial with the axis the drive shaft is oriented and that on the spring element in Area of the roll is fixed to a start-up element, which is a displacement the role limited in the direction of the axis of the drive shaft. there can also provide another starting element in the opposite direction be on both sides a shift of the role in the direction of Limit the axis of the drive shaft. This can be a tarnish protection for the spring element and at the same time a certain centering the role to be ensured in relation to the cam. Furthermore, unwanted conditions, where the skate and / or the role is no longer essential coaxially oriented to the axis of the drive shaft, avoided become. This allows a high reliability of the high-pressure pump 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 in egg ner groove-shaped recess of the skate be at least partially used.

Further it is advantageous that another spring element is provided, on the one hand by means of the retaining bracket with the piston of the the first pump assembly and on the other hand at least indirectly with the Piston of the second pump assembly is connected, 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 according to the Be developed further spring element.

In Advantageously, the first pump arrangement of a cylinder head closed, on which a projecting into the first pump assembly approach is formed, wherein formed in the approach, a cylinder bore and the piston is a pump work space in the cylinder bore limited and wherein an outer diameter of the neck at least substantially equal to an inner diameter of the bore in one Basic body of a housing is in which the first Pump assembly is used. Thus, the approach in the field the cylinder bore a relatively large wall thickness have, so that in operation high pressures in the pump working space achievable are. Furthermore, a high efficiency of the high-pressure pump can be achieved be because elastic deformation of the cylinder head, in particular in the region of the approach in which the cylinder bore is formed is reduced.

The second pump assembly may be according to the first pump assembly be educated. This also results for the second pump assembly the corresponding benefits.

Brief description of the drawings

preferred Embodiments of the invention are in the following Description with reference to the accompanying drawings, in which corresponding elements with matching references are provided, explained in more detail. It shows:

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

2 an excerpted section through the in 1 shown high pressure pump along the designated II line and

3 an excerpted section through the in 1 shown high pressure pump according to a second embodiment of the invention.

embodiments the invention

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 consists of a fuel injection system with a fuel rail, a so-called common rail that stores diesel fuel under high pressure. The high-pressure pump according to the invention 1 However, it is also suitable for other applications.

The high pressure pump 1 has a multi-part housing 2 on. Furthermore, the high-pressure pump 1 a drive shaft 3 on, around their axis 4 rotates during operation. The drive shaft 3 is on the one hand at a storage location 5 in a basic body 6 of the housing 2 stored. On the other hand, the drive shaft 3 at a depository 7 in one with the main body 6 connected flange part 8th of the housing 2 stored. The two bearings 5 . 7 are in relation to the axis 4 axially spaced from each other.

Between the two bearings 5 . 7 has the drive shaft 3 a cam 9 on, which may also be designed as a multiple cam. The concept of the cam 9 includes also embodiments of the drive shaft 3 in which, for example, the cam 9 through an eccentric to the axis 4 formed section on the drive shaft 3 is formed.

The main body 6 of the housing 2 has a first hole 15 and at least a second bore 16 on that in relation to the axis 4 the drive shaft 3 are arranged in mutually opposite radial directions. In the first hole 15 of the basic body 6 is a first pump assembly 17 arranged. Further, in the second bore 16 of the basic body 6 a second pump assembly 18 arranged. The structure and function of the pump assemblies 17 . 18 are mainly based on the first pump assembly 17 described. The structure of the second pump assembly 18 essentially corresponds to that of the first pump assembly 17 ,

The first hole 15 is of a serving as a cylinder head housing part 19 locked. Further, the second pump assembly 18 from a likewise serving as a cylinder head housing part 20 locked. The housing part 19 has an approach 21 in which a cylinder bore 22 is designed. In the cylinder bore 22 is a piston 23 arranged in the cylinder bore 22 is slidably mounted. The piston 23 limits a pump work space 24 in the cylinder bore 22 , The pump workroom 24 is with a fuel channel 25 connected in which one to the pump work space 24 opening intake valve 26 is arranged. Further, the pump work space 24 with a fuel channel 27 connected, in which an outlet valve 28 is arranged, which has the main function, a return of fuel from the fuel channel 27 into the pump workroom 24 to prevent. Via the outlet valve 28 and the fuel channel 27 can during operation of the high-pressure pump 1 be conveyed under high pressure fuel to a fuel rail.

In the hole 15 of the basic body 6 of the housing 2 is a plunger body 30 arranged in the hole 15 is guided. The plunger body 30 is preferably made relatively thin-walled. This can be an outside diameter 31 of the approach 21 essentially the same size as an inner diameter 32 the bore 15 be. This allows a relatively thick-walled design of the approach 21 that is a wall of the neck 21 around the cylinder bore 22 , This can cause a high pressure in the pump working space 24 be generated, wherein an elastic expansion of the housing part 19 , especially in the area of the approach 21 , is avoided. This also allows high pressure generation efficiency.

The pump assembly 17 has a roller skate 35 on, the one on the cam 9 the drive shaft 3 ongoing role 36 receives. The role 36 is at least substantially coaxial with the axis 4 the drive shaft 3 oriented. The piston 23 relies on a covenant 37 of the piston 23 on the roller skate 35 from.

The high pressure pump 1 has a spring element 40 and another spring element 41 on. The spring elements 40 . 41 are in relation to the axis 4 the drive shaft 3 axially spaced from each other. Furthermore, the spring elements 40 . 41 on different sides of the cam 9 the drive shaft 3 arranged. The spring elements 40 . 41 enclose the drive shaft 3 as well as on the basis of the 3 is illustrated.

About the spring elements 40 . 41 is the piston 23 the first pump assembly 17 with a piston 23 ' the second pump assembly 18 connected. Here are the spring elements 40 . 41 on the one hand indirectly with the piston 23 connected and on the other hand indirectly with the piston 23 ' connected. 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 arises in a corresponding way.

The first pump assembly 17 has a headband 45 on top of the piston 23 above the covenant 37 that is from the axis 4 viewed from radially outside, embraces. The headband 45 this can cause the piston 23 with respect to rotational forces occurring during operation in abutment with the skate 35 hold. The headband 45 is with the spring elements 40 . 41 connected, in turn, with the piston 23 ' are connected. In this case, the spring elements 40 . 41 under a certain bias, so that the headband 45 the covenant 37 of the piston 23 against the roller skate 35 squeezes over the role 36 on the cam 9 supported. This will cause the piston 23 , the roller skate 35 , the role 36 and the cam 9 each held in contact with each other.

The first pump assembly 17 also has startup elements 46 . 47 on, taking a pin-shaped approach 46 ' of the starting element 46 the spring element 40 with the headband 45 connects while a pin-shaped approach 47 ' of the starting element 47 the headband 45 with the further spring element 41 combines. The starting elements 46 . 47 limit a coaxial displacement of the role 36 , so that within certain limits, a centering of the role 36 in relation to the tread of the cam 9 is reached. As a result, a tilting or pivoting, that is, a non-coaxial barrel, the role 36 relative to the axis 4 avoided or at least limited in extent, so that a reliable operation of the high-pressure pump 1 is guaranteed.

The cam 9 serves both to drive the first pump assembly 17 as well as the second pump assembly 18 , By the spring elements 40 . 41 become the respective elements of the pump assemblies 17 . 18 held together, allowing a reliable operation of the high pressure pump 1 allows, with separate return springs for the pistons 23 . 23 ' the pump assemblies 17 . 18 each can be saved. This allows, inter alia, the relatively thick-walled design of the approach 21 around the cylinder bore 22 the first pump assembly 17 and a corresponding embodiment of the second pump assembly 18 , This results in a high efficiency of the high-pressure pump 1 and / or the ability to deliver fuel under high pressure to a common rail or the like.

2 shows an excerpted section through the in 1 shown high pressure pump 1 along with 11 designated cutting line according to the embodiment of the first embodiment of the invention. The headband 45 is bandför mig configured and in a groove-shaped recess 48 in a roller skate 35 inserted. It also the spring elements 40 . 41 at least partially in the groove-shaped recess 48 of the roller skate 35 be inserted. By inserting the retaining clip 45 and optionally the spring elements 40 . 41 in the groove-shaped recess 48 becomes a twist of the skate 35 in terms of a desired location in which the role 36 coaxial to the axis 4 the drive shaft 3 is guided prevented. Thus, a coaxial run of the roll 36 to the drive shaft 3 achieved. This can be a high reliability of the high pressure pump 1 be guaranteed.

3 shows an excerpted section through a high-pressure pump 1 along the in 1 designated III cutting line according to a second embodiment of the invention. Here is the headband 45 at the height of an axis 49 of the piston 23 cut back shown to the view of the spring element 40 , the groove-shaped recess 48 and the roller skate 35 to enable. The spring element 40 has a band-shaped section 49 on. The band-shaped section 49 has a circular opening 50 on, through which the pin-shaped approach 46 ' of the starting element 46 extends. The pin-shaped approach 46 ' of the starting element 46 also extends through a corresponding opening in the headband 45 so that the spring element 40 at its band-shaped section 49 Reliable with the headband 45 connected is. Further, the band-shaped portion 49 of the spring element 40 partially in the groove-shaped recess 48 of the roller skate 35 used, allowing a twisting of the skate 35 is prevented from its desired location.

The spring element 40 can the drive shaft 3 outside the area of the cam 9 enclose or within the range of the cam 9 be arranged so that the spring element the cam 9 the drive shaft 3 encloses circumferentially. The spring element 40 is preferably mounted biased, so that the spring element 40 the piston 23 in the direction of the drive shaft 3 biases. As a result, especially in the area of the approach 21 of the cylinder head serving as the housing part 19 a separate return spring omitted. The spring element 40 is as an annular spring element 40 designed so that a uniform force transmission between the first pump assembly 17 and the second pump assembly 18 for returning the pistons 23 . 23 ' is made possible depending on the respective operating position. In accordance with the embodiments of the invention designed high-pressure pump 1 are the pistons 23 . 23 ' via at least one spring element 40 connected together so that return or return springs in the pump assemblies 17 . 18 can be saved. The space saved in relation to a design with return or return springs can be used to the approach 21 of the cylinder head serving as the housing part 19 in the area of the bore 15 as a guide for the ram body 30 serves to reinforce, so that an expansion of serving as a cylinder head housing part 19 is reduced under high pressure.

Furthermore, the spring element runs 40 in the area of the roller skate 35 in a groove-shaped recess 48 , causing a twist of the skate 35 is prevented.

The spring element 40 can additionally in the area of the role 36 a tarnish protection by a starting element 46 take over, at the same time the connector for the spring element 40 with the headband 45 is.

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

The Invention is not limited to the described embodiments limited.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102005046670 A1 [0002, 0003]

Claims (10)

High pressure pump ( 1 ), in particular 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 to the drive shaft ( 3 ) at least approximately opposite to the second pump assembly ( 18 ) is arranged, wherein the drive shaft ( 3 ) at least one cam ( 9 ) for driving the first pump assembly ( 17 ) and the second pump assembly ( 18 ), and wherein at least one spring element ( 40 ) is provided, 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 ) connected is. High-pressure pump according to claim 1, characterized in that the spring element ( 40 ) as an annular spring element ( 40 ) is configured. High-pressure pump according to claim 2, characterized in that the annular spring element ( 40 ) the drive shaft ( 3 ) encloses. High-pressure pump according to one of claims 1 to 3, characterized in that the first pump assembly ( 17 ) a roller skate ( 35 ), one on the cam ( 9 ) of the drive shaft ( 3 ) running role ( 36 ) and that the skate ( 35 ) a groove-shaped recess ( 48 ), in which the spring element ( 40 ) is at least partially arranged. High-pressure pump according to claim 4, characterized in that the spring element ( 40 ) a band-shaped section ( 49 ) and that the band-shaped section ( 49 ) of the spring element ( 40 ) at least partially in the groove-shaped recess ( 48 ) of the skate ( 35 ) is inserted. High-pressure pump according to claim 4 or 5, characterized in that the roller ( 36 ) at least substantially coaxial with an axis ( 4 ) of the drive shaft ( 3 ) and that on the spring element ( 40 ) in the area of the role ( 36 ) at least one starting element ( 46 . 47 ), which is a displacement of the roller ( 36 ) in the direction of the axis ( 4 ) of the drive shaft ( 3 ) limited. High-pressure pump according to one of claims 1 to 6, characterized in that the first pump arrangement ( 17 ) a headband ( 45 ) having the piston ( 23 ) of the first pump assembly ( 17 ) with the spring element ( 40 ) connects. 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 retaining clip ( 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 ), 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 apart on different sides of the cam ( 9 ) of the drive shaft ( 3 ) are provided. High-pressure pump according to one of claims 1 to 8, characterized in that the first pump assembly ( 17 ) of a cylinder head ( 19 ) is closed at the one in the first pump assembly ( 17 ) excellent approach ( 21 ), that in the approach ( 21 ) a cylinder bore ( 22 ) is formed, wherein the piston ( 23 ) a pump work space ( 24 ) in the cylinder bore ( 22 ) and that an outer diameter ( 31 ) of the approach ( 21 ) substantially equal to an inner diameter ( 32 ) of a bore ( 15 ) in a basic body ( 6 ) of a housing ( 2 ) into which the first pump assembly ( 17 ) is used. High pressure pump according to claim 9, characterized in that the spring element ( 40 ) the piston ( 23 ) in the direction of the drive shaft ( 3 ) and that in the area of the approach ( 21 ) of the cylinder head ( 19 ) no separate return spring is provided.