DE102004002489B4 - Fluid pump, in particular high-pressure fuel pump - Google Patents

Abstract

A fluid pump (20), in particular a high-pressure fuel pump, comprises a pump housing (42, 44) and an inlet (18). A delivery chamber (32) is bounded by at least one movable conveyor (30). It is proposed that the fluid pump (20) comprises a pressure damper (40) which damps inlet-side pressure fluctuations and which comprises at least one gas volume (72) enclosed between two diaphragms (58, 60), which in one on a housing body (42) Housing cover (44) of the fluid pump (20) is received, and that edge portions (66, 68) of the two membranes (58, 60) between at least two holding elements (74, 76) are held, which in turn in the housing cover ( 44) are held.

Description

State of the art

The invention relates to a fluid pump, in particular a high-pressure fuel pump, with a pump housing, an inlet, and a delivery chamber, which is bounded by at least one movable conveyor.

A fluid pump of the type mentioned is from the DE 195 39 885 A1 known and used for example in internal combustion engines with direct fuel injection. In such internal combustion engines, the fuel from the fluid pump is compressed to a high pressure and conveyed into a fuel rail. From this, the fuel passes under high pressure via fuel injectors directly into the combustion chambers of the internal combustion engine. The fluid pump sucks the fuel via a low pressure port and an inlet valve into a delivery chamber. This is limited by a delivery piston.

To compensate for pressure fluctuations in a fuel line, which is connected to the low pressure port, a pressure damper is arranged there. This includes a spring loaded piston defining a damping chamber connected to the fuel line via a bag port.

From the US2003 / 0164161 A1 is given a fluid pump according to the preamble of claim 1. Another fluid pump is out of the DE69814548 T2 known.

Object of the present invention is to provide a fluid pump of the type mentioned in such a way that on the one hand has the smallest possible dimensions and on the other hand can be easily produced.

This object is achieved in a fluid pump of the type mentioned above in that it comprises an integrated pressure damper which damps inlet-side pressure fluctuations and which comprises at least one gas volume enclosed between two membranes, which is accommodated in a housing cover of the fluid pump attached to a housing body of the fluid pump, and that edge portions of the two membranes are held between at least two retaining elements, which in turn are held in the housing cover.

Advantages of the invention

By using a sealed volume of gas, the compressibility of gases can be exploited to ensure the elastic movement of the membranes required to dampen pressure pulsations. Such a gas volume can be realized in almost any geometric shape. It can therefore be integrated very space-saving in the fluid pump. The placement of the pressure damper within the pump housing also saves a complex wiring with corresponding leakage problems. The holder of the two membranes between two holding elements, which in turn are held in the housing cover, allows a pre-assembly of the pressure damper. This leads to a simplification of the assembly of the fluid pump as a whole and thus to a reduction in their manufacturing costs. Overall, an inexpensive and at the same time compact fluid pump is created on the basis of the features according to the invention.

Advantageous developments of the invention are specified in subclaims.

First, it is proposed that the housing cover toward the housing body towards an at least substantially open side includes a free edge having a radially inwardly facing bend, and that the housing body facing the holding element is supported on the fold. Such a Umbug can be made easily and inexpensively, for example, by crimping the free edge of the housing cover. The Umbug ensures, without additional steps or separate elements are required for a secure mounting of the housing body facing the holding element. In addition, a connection between the housing body and housing cover must accommodate only the hydraulic forces, but not the preload forces.

It is also proposed that the housing cover comprises a closed side facing away from the housing body, and preferably that the holding elements relative to the housing cover are rigid, and that the holding elements between the fold and the closed side are braced. In this case, the unit consisting of the pressure damper and the housing cover can be preassembled and pre-tested in a particularly simple and inexpensive manner, since the pressure damper in the housing cover is held captive after the manufacture of the umbilicus. Due to the elastic spring force of the Umbugs beyond the pressure damper in the housing cover is immovably positioned without additional steps are required. Preferably, the axial bias is applied by the housing cover itself. Consequently, the attachment essentially only needs to absorb the hydraulic forces that occur during operation.

A particularly advantageous embodiment of the fluid pump according to the invention provides that the fold is attached to a flat end face of the housing body. In this case, the Umbug fulfills two functions: on the one hand, the mounting of the pressure damper within the housing cover, and on the other hand, it serves as a mounting flange of the pressure damper and the housing cover unit on the housing body of the fluid pump. For example, it is possible to dispense with a special rotation on the housing body. This also simplifies the handling in the production and thus lowers the production costs. In addition, the height is reduced.

In a further development, it is proposed that the diameter of the planar end face of the housing body is smaller than the maximum diameter of the housing cover. In this way, a high damping effect can be achieved by a corresponding large volume of gas while small dimensions of the housing body. This reduces the overall dimensions of the fluid pump and also leads to a cost reduction due to the lower use of material in the housing body.

A further advantageous embodiment provides that a peripheral wall of the housing cover has at least one circumferential and radially inwardly directed concavity or at least two separate radially inwardly directed indentations, and that the concavity (s) engages or engage in a recess of the housing body facing the retaining element , This is an alternative or additional possibility of fixing the housing body-facing holding element to the above-described fold. For the preparation of the concavity (s) simple tools can be used. In addition, such a concavity offers the opportunity to first position the holding element in a desired position and then introduce the concavity and thus fix the holding element in the desired and optimal position.

A defined holding force is exerted on the two membranes when one of the holding elements comprises a plate spring. Such a plate spring also has the advantage that the special spring material retains a spring stiffness over a long period of time, which extends the overall life of the fluid pump.

In this case, the costs can be further reduced if one of the two holding elements or both holding elements is or are rigid.

It is also advantageous if the housing cover has at least one shoulder on which the housing element facing the holding element is supported towards the membrane. This allows in the production of a simple and reproducible positioning of the housing body facing the holding element, which simplifies the production and thus reduces the manufacturing costs and what also leads to an extended life of the fluid pump according to the invention.

For the effectiveness of the pressure damper according to the invention, it is advantageous if abut the pressure pulsations to be damped at both membranes. Therefore, it is proposed in a further advantageous embodiment of the fluid pump according to the invention that in the holding elements, a fluid connection is present, which connects an existing space between the housing body and the pressure damper with an existing space between the housing cover and the pressure damper.

Reproducible construction conditions can also be ensured in a simple manner in that the radially outer edge of at least one of the two membranes is centered by the peripheral wall of the housing cover, in particular by concavities present there.

It is also proposed that the two membranes are welded together in the region of their edges, and that the holding elements engage the membranes radially inwardly from the weld. By welding at the edges of the trapped gas volume is maximum, and such welding can be made relatively inexpensive. By engaging radially inwardly of the welding retaining elements, the welding is relieved during operation of the pressure damper, which extends the life of the pressure damper and thus the fluid pump as a whole.

Another advantageous embodiment of the fluid pump according to the invention is characterized in that at least one of the two holding elements is produced as a cold-formed part or as a sintered part.

drawing

Hereinafter, particularly preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. In the drawing show:

1 a schematic representation of a fuel system of an internal combustion engine having a fluid pump with an integrated pressure damper;

2 a partial longitudinal section through the fluid pump of 1 ;

3 a view III of 2 ;

4 a section through a portion of an alternative embodiment of a fluid pump; and

5 a section through a further modified embodiment of a fluid pump.

Description of the embodiments

In 1 a fuel system carries the overall reference numeral 10 , It includes a fuel tank 12 , from which a prefeed pump the fuel into a low-pressure line 16 promotes. This leads to a low pressure connection 18 a designed as a high-pressure piston pump fluid pump 20 , in the 1 is indicated by a dashed line.

A high pressure connection 22 the high-pressure piston pump 20 is with a fuel rail 24 connected. This is also called "Rail". In it is the one of the high pressure piston pump 20 compressed fuel stored under high pressure. To the fuel manifold 24 are several fuel injectors 26 connected to the fuel in their respective associated combustion chamber 28 inject directly. The fuel system 10 So belongs to an internal combustion engine with direct fuel injection.

This in 1 shown hydraulic diagram of the high-pressure piston pump 20 shows some of its essential components: This includes a delivery piston 30 , which can be offset from a drive shaft, not shown, for example, in a reciprocating motion. He limits a delivery room 32 , This is with an inlet valve device 34 and an exhaust valve 36 fluidly connected. Between the low pressure connection 18 and the intake valve device 34 is in a flow path 38 a pressure damper 40 arranged.

By means of the inlet valve device 34 can the flow rate of the high-pressure piston pump 20 be set. For this purpose, during a delivery stroke of the delivery piston 30 the inlet valve device 34 forcibly opened. In this case, during the delivery stroke of the delivery piston 30 the fuel does not go to the fuel rail 24 but back over the flow path 38 in the low pressure line 16 pushed out. Among other things, this in the flow path 38 and in the low pressure line 16 occurring pressure pulsations are from the pressure damper 40 smoothed.

How out 2 it can be seen comprises the high-pressure piston pump 20 a housing with a cylindrical housing body 42 and one on an end face of the case body 42 arranged housing cover 44 , While it is the case body 42 is a rotating part, is the housing cover 44 formed according to the invention as a shaped sheet metal part, for example formed from stainless steel sheet. In the housing body 42 is a piston sleeve 46 recorded, in which the delivery piston 30 is guided axially displaceable. The pump room 32 is over in 2 non-visible channels connected to an inlet bore leading to the flow path 38 belongs. In this an inlet nozzle is used, which is the low pressure port 18 forms. Via a branch channel 50 is the inlet hole 38 with a between the housing body 42 and the housing cover 44 formed recording room 52 connected, in which the pressure damper 40 is included. These will be discussed in greater detail below. The pump room 32 is via the exhaust valve 36 also with an outlet hole 56 connectable, and in the outlet hole 56 an outlet is arranged, which is the high pressure port 22 forms.

The pressure damper 40 comprises two generally parallel membranes 58 and 60 , which has a central and with concentric beads (no reference numeral) provided spring portion 62 respectively 64 as well as a plan and peripheral edge section 66 respectively 68 exhibit. The two edge sections 66 and 68 are welded together at their radially outer free edge (position 70 ). Between the two membranes 58 and 60 is a gas volume 72 locked in.

The two circumferential and adjoining edge sections 66 and 68 are between the welding 70 and the spring sections 62 and 64 between two annular retaining elements 74 and 76 jammed. For this purpose, the two holding elements 74 and 76 in each case in the radially inner and to the spring sections 62 and 64 the membranes 58 and 60 located area over a chamfer 77 (For illustrative reasons, this is only on the upper holding element 74 provided with a reference numeral). Analogous to this is a radially outer and the edge portions 66 and 68 the two membranes 58 and 60 facing region of the two holding elements 74 and 76 with a cut-out 79 Mistake. This results in a relatively small and collar-like axially extending holding area (without reference numeral) on each holding element 74 and 76 at the respective edge section 66 respectively 68 a membrane 58 and 60 between the spring section 62 respectively 64 and the welding 70 can attack. As a result, during operation of the pressure damper 54 the welding 70 relieved.

The two retaining elements 74 and 76 are as cold impact parts, for example, by cold forming made of brass pipe sections or sheet brass strips. Alternatively, they can also be produced as sintered parts. In the in 2 outer boundary surfaces of the two holding elements 74 and 76 are distributed over the circumference radially and axially extending notches 78 respectively 80 imprinted (compare also 3 ). As a result, a between the membrane 60 of the pressure damper 40 and the housing body 42 educated area 82 of the recording room 52 with one between the membrane 58 and the housing cover 44 formed upper area 84 of the recording room 52 fluidly connected.

The pressure damper 40 with its two membranes 58 and 60 is over the two holding elements 74 and 76 in the housing cover 44 held tight. For this the housing cover has 44 over a closed lid section 86 whose central area 88 is slightly curved outward and its radially outer region 90 runs exactly radially. To the closed lid section 86 closes to the housing body 42 towards an axially extending closed peripheral wall 92 at. Their free edge is bent radially inward, what as a Umbug 94 referred to as. The two retaining elements 74 and 76 with the membranes held between them 58 and 60 are in turn between the radially outer region 90 the lid section 86 of the housing cover 44 and the umbug 94 axially jammed. At the same time are the two holding elements 74 and 76 radially on the peripheral wall 92 of the housing cover 44 at. The two retaining elements 74 and 76 and thus also the pressure damper 54 are therefore rigid and immovable in the housing cover 44 added. The Umbug 94 is with a flat face 96 of the housing body 42 in 98 welded. It should be noted that the diameter of the housing body 42 smaller than the diameter of the housing cover 44 , This is made possible by the fact that the welding 98 between the housing cover 44 and the housing body 42 in the region of the radially inner edge of the Umbugs 94 lies.

The high pressure piston pump 20 with the pressure damper 54 is mounted as follows:
First, the housing cover 44 made, but still without Umbug 94 , After welding the two membranes 58 and 60 (Position 70 ) is first the retaining element 74 in the housing cover 44 inserted, and then the actual pressure damper 54 coming from the two membranes 58 and 60 and the enclosed gas volume 72 exists on the holding element 74 placed. Then the holding element 76 positioned and the umbug 94 produced for example by crimping. The housing cover 44 thus forms with the pressure damper 54 a pre-assembled and testable unit. Subsequently, the housing cover 44 directly on the flat face 96 of the housing body 42 put on and with this in 98 welded.

As has already been explained above, the high-pressure piston pump is in operation 20 systemic, for example, in the inlet bore 38 to pressure pulsations. These are through the pressure damper 40 smoothed. This is the inlet hole 38 over the stitch canal 50 with the area 82 of the recording room 52 connected, which of the membrane 60 of the pressure damper 40 is limited. About the notches 78 and 80 but it is also the area 84 of the recording room 52 which is attached to the membrane 58 of the pressure damper 40 adjoins, with the stitch channel 50 and thus with the inlet hole 38 connected.

In 4 is one area of an alternative embodiment of a high pressure piston pump 20 shown. Here and in subsequent figures, those elements and regions which have equivalent functions to previously mentioned elements and regions have the same reference numerals. They are normally not explained in detail again.

A first difference of in 4 shown high-pressure piston pump 20 to that of the 2 and 3 is that the holding element 74 not designed as a rigid ring, but as a plate spring. Thus, when flanging the umbug 94 a lower accuracy required because the clamping force, which the two holding elements 74 and 76 on the pressure damper 40 exercise, essentially through the diaphragm spring 74 is given. Furthermore, the peripheral wall has 92 of the housing cover 44 over a plurality of circumferentially distributed and radially inwardly directed indentations or beads 100 , which have two functions: First, through them the pressure damper 40 radially in the housing cover 44 centered. On the other hand form the beads 100 each paragraphs 102 , where the retaining element 76 axially to the pressure damper 40 supported. This results in a precise adjustment of the biasing force of the plate spring 74 ,

A further modified variant of a high-pressure piston pump 20 is in 5 shown: In this, the holding element 76 in its radially outer peripheral wall a circumferential groove 104 on. A change is dispensed with in this variant. Instead, in the manufacture of the housing cover 44 and pressure damper 40 existing unit after insertion of the diaphragm spring 74 and the pressure damper 40 the holding element 76 force introduced until a desired preload force is reached. Then the peripheral wall 92 of the housing cover 44 locally in several places 106 deformed radially, causing the retaining element 76 is axially fixed.

Claims (13)

Fluid pump ( 20 ), in particular high-pressure fuel pump, with a pump housing ( 42 . 44 ), an inlet ( 18 ), and a delivery room ( 32 ) of at least one movable subsidy ( 30 ), with an integrated pressure damper ( 40 ) attenuating the inlet side pressure fluctuations and the at least one between two membranes ( 58 . 60 ) enclosed gas volume ( 72 ), characterized in that it is mounted in a housing body ( 42 ) of the fluid pump ( 20 ) attached housing cover ( 44 ) of the fluid pump ( 20 ) and that edge portions ( 66 . 68 ) of the two membranes ( 58 . 60 ) between at least two retaining elements ( 74 . 76 ) are held, which in turn in the housing cover ( 44 ) are held, and that the housing cover is formed without cutting as a sheet metal part. Fluid pump ( 20 ) according to claim 1, characterized in that the housing cover ( 44 ) to the housing body ( 42 ) comprises an at least substantially open side with a free edge, which has a radially inwardly facing turn (FIG. 94 ), and that the housing body ( 42 ) facing holding element ( 76 ) at the Umbug ( 94 ) is supported. Fluid pump ( 20 ) according to claim 2, characterized in that the housing cover ( 44 ) one of the housing body ( 42 ) facing away from the closed side ( 86 ), and preferably that the retaining elements ( 74 . 76 ) relative to the housing cover ( 44 ) are rigid, and between the Umbug ( 94 ) and the closed side ( 86 ) are braced. Fluid pump ( 20 ) according to one of claims 2 or 3, characterized in that the fold ( 94 ) on a flat face ( 96 ) of the housing body ( 42 ) is attached. Fluid pump ( 20 ) according to claim 4, characterized in that the diameter of the plane end face ( 96 ) of the housing body ( 42 ) is smaller than the maximum diameter of the housing cover ( 44 ). Fluid pump ( 20 ) according to one of the preceding claims, characterized in that a peripheral wall ( 92 ) of the housing cover ( 44 ) at least one circumferential and radially inward curvature ( 106 ) or at least two separate radially inwardly directed indentations, and that the concavity (s) ( 106 ) in a recess ( 104 ) of the housing body ( 42 ) facing the retaining element ( 76 ) intervenes or intervene. Fluid pump ( 20 ) according to one of the preceding claims, characterized in that one of the two holding elements is a disc spring ( 74 ). Fluid pump ( 20 ) according to claim 7, characterized in that one of the two holding elements ( 76 ) is rigid. Fluid pump ( 20 ) according to one of the preceding claims, characterized in that the housing cover ( 44 ) at least one paragraph ( 102 ), on which the housing body ( 42 ) facing holding element ( 76 ) to the membrane ( 60 ) is supported. Fluid pump ( 20 ) according to one of the preceding claims, characterized in that in the holding elements ( 74 . 76 ) a fluid connection ( 78 . 80 ) is present, which one between the housing body ( 42 ) and the pressure damper ( 40 ) existing space ( 82 ) with a between the housing cover ( 44 ) and the pressure damper ( 40 ) existing space ( 84 ) connects. Fluid pump ( 20 ) according to one of the preceding claims, characterized in that the radially outer edge of at least one of the two membranes ( 58 . 60 ) by a peripheral wall ( 92 ) of the housing cover ( 44 ), in particular by there existing indentations or beads ( 100 ), is centered. Fluid pump ( 20 ) according to one of the preceding claims, characterized in that the two membranes ( 58 . 60 ) are welded together in the region of their edges ( 70 ), and that the retaining elements ( 74 . 76 ) on the membranes ( 58 . 60 ) radially inward of the weld ( 70 attack). Fluid pump ( 20 ) according to one of the preceding claims, characterized in that at least one of the two retaining elements ( 74 . 76 ) is produced as a cold-formed part or as a sintered part.

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