Fluid pump and method for producing a fluid pump

Abstract

The invention relates to a method for producing a fluid pump and to a fluid pump, in particular an oil pump, having a housing, wherein a chamber extends along a first direction starting from a first end face of the housing to a second end face of the housing, wherein a piston is movably arranged in a pump section of the chamber, wherein an at least annular sealing section of the piston sealingly rests against an inner wall of the pump section of the piston chamber, wherein a delivery line is formed in the piston, wherein the delivery line extends from a first end face of the piston to a second end face of the piston, wherein the first end face of the piston is arranged outside the chamber, wherein the second end face of the piston is arranged inside the chamber, wherein the delivery line is designed to conduct fluid from the first end face of the piston into the chamber, wherein the piston and / or the housing are made of cold-formed metal.

Description

[0001] R.411995

[0002] - 1 -

[0003] Description

[0004] title

[0005] Fluid pump and method for manufacturing a fluid pump

[0006] The invention relates to a fluid pump and a method for manufacturing a fluid pump, in particular an oil pump.

[0007] State of the art

[0008] In the prior art, the housing and piston of a fluid pump are manufactured using machining or forming processes.

[0009] This approach has the disadvantage that production is time-consuming.

[0010] The object of the invention is to provide a fluid pump and a method for manufacturing a fluid pump that can be manufactured using simpler technical methods and, in particular, more quickly.

[0011] Disclosure of the invention

[0012] The problem of the invention is solved by the features of the independent patent claims.

[0013] A fluid pump, in particular an oil pump, is proposed, comprising a housing, wherein a chamber extends along a first direction from a first end side of the housing to a second end side of the housing, wherein a piston is movably arranged in a pumping section of the chamber, wherein at least annular sealing section of the piston seals against an inner wall of the pumping section of the piston chamber. R.411995

[0014] - 2 - is located, wherein a delivery line is formed in the piston, the delivery line extending from a first end of the piston to a second end of the piston, the first end of the piston being arranged outside the chamber, the second end of the piston being arranged in the chamber, the delivery line being designed to convey fluid from the first end of the piston into the chamber, the piston and / or the housing being made of cold-formed metal. This eliminates the need for complex machining processes.

[0015] One advantage of the proposed fluid pump and method is that the pump and the process can be manufactured more easily and, in particular, more quickly. Furthermore, the piston and / or housing are less susceptible to wear, since at least parts of the piston and / or housing exhibit greater hardness due to the cold forming process.

[0016] In addition, the edge and corner areas, which are advantageous thanks to the cold forming process, are formed so that fewer deposits can accumulate there.

[0017] Particularly at constrictions or narrowings of a flow path, the relatively large radii of curvature created by cold forming result in less flow loss, as the fluid flows less turbulently. Specifically, the cold forming process creates larger radii of curvature at the corners of the piston, facilitating easier installation of the piston into the housing chamber and simplifying its guidance within the chamber. These radii of curvature can range, for example, from 0.3 mm to 1 mm.

[0018] Preferably, extruded parts are used for the housing and / or the piston, which are then brought into their final shape using a cold forming process and appropriate forming tools. R.411995

[0019] - 3 -

[0020] The chamber has a first section at the first end of the housing, the first section having a cross-section that tapers conically towards the second end of the housing, the pump section adjoining the first section, the first section being cold-formed. The first section facilitates the insertion of the piston into the pump section during assembly.

[0021] In one embodiment, the chamber has a third section extending from the pump section towards the second end face. This third section has a cross-section that tapers conically towards the second end face and is cold-formed. The cold forming process gives the third section high strength. Furthermore, the transitions to and from the third section have relatively large radii of curvature due to the cold forming process, resulting in less turbulence in the fluid flow into and out of the third section.

[0022] In one embodiment, the pump section transitions into the third section via a tapered stage, where the tapered stage is an annular surface oriented transversely to the longitudinal extent of the chamber. This annular surface can be manufactured by cold forming, resulting in relatively high hardness. Furthermore, the radii of curvature at the edge of the annular surface are relatively large, leading to minimal turbulence in the fluid flow.

[0023] In one embodiment, a spring element is provided in the chamber, which biases the piston towards the first end of the housing. This improves the pumping function of the piston.

[0024] In one embodiment, the housing has a retaining tab at its first end that curves towards the center of the chamber, the retaining tab forming a holding surface that holds the piston in the chamber. This provides a simple and easily manufactured holding surface for the piston. R.411995

[0025] - 4 -

[0026] In one embodiment, the piston has an annular surface between the sealing section and the first end, across which the cross-section of the piston transitions from the larger cross-section of the sealing section to the smaller cross-section of a first end section. This annular surface is arranged transversely to the longitudinal extent of the piston and constitutes an additional retaining surface, which abuts the retaining surface of the retaining tab. In this way, an additional retaining surface is provided using simple means.

[0027] In one embodiment, the delivery line extends from the first end face of the piston, wherein a recess is provided in the first end face, the recess extending from a lateral edge of the piston to the delivery line, the recess facilitating fluid flow into the delivery line when the first end face of the piston rests against a housing wall. This ensures a reliable supply of fluid to the delivery line.

[0028] In one embodiment, the housing and / or piston are made of the following materials: steels suitable for cold forming. However, copper alloys, wrought copper alloys, bearing steels, aluminum alloys, etc., are also suitable. Preferably, steel, in particular 20MnB4 (easily cold-formable) or 38B2, can be used for the housing. The piston can, for example, be made of aluminum with a strength class of T6 (90 HB).

[0029] Tubular blanks can be used for both the housing and the piston, which are then formed into the housing or piston using a cold forming process. In particular, the entire inner surface and / or the entire outer surface of the blank can be cold formed.

[0030] A method for manufacturing a fluid pump according to one of the preceding claims is described, wherein the piston and / or the housing are made of a cold-formed metal.

[0031] In one embodiment, at least a section of the housing chamber was formed using a cold forming process. R.411995

[0032] - 5 - In one embodiment, at least a section of the piston was formed using a cold forming process.

[0033] In one embodiment, during assembly, the piston is inserted into the chamber of the housing through the first end of the housing. Subsequently, a section of material from this first end of the housing is bent towards the center of the chamber, forming a contact surface that holds the piston in place. This provides a simple assembly method with reliable piston retention within the chamber.

[0034] Exemplary embodiments of the proposed fluid pump and the proposed method are explained in more detail with reference to the figures. These show:

[0035] Fig. 1 shows a schematic representation of a pumping device,

[0036] Fig. 2 shows a schematic cross-section through a fluid pump after the piston has been mounted.

[0037] Fig. 3 is a perspective view of a partial cross-section of Fig. 2, Fig. 4 is a perspective view of the arrangement of Fig. 3 after bending the retaining tabs.

[0038] In cold forming processes, such as those defined in DIN 8580, metals are work-hardened at temperatures significantly below their recrystallization temperature. They are made more resilient by applying high forming forces (compressive and tensile forces). Cold forming processes can include, for example, pressing, deep drawing, rotary swaging, cold drawing, cold forging, cold upsetting, and / or cold extrusion.

[0039] Fig. 1 shows a schematic cross-sectional view of a pump device 1, which has a device housing 2, wherein a movable element 3 is arranged in the device housing 2. The movable element 3 is moved in a cyclic back-and-forth motion relative to R.411995 by an actuator (not shown), for example an electromagnet.

[0040] - 6 - moves back and forth relative to a housing wall 4 in a y-direction. A housing spring element 5 can be arranged between the movable element 3, which is designed, for example, in the form of a plate, and the housing wall 4. A fluid pump 6 is arranged between the movable element 3 and the housing wall 4.

[0041] The fluid pump 6 has a housing 7 and a piston 8 projecting from the housing 7 towards the housing wall 4. The piston 8 rests on the housing wall 4 with a first end face 9. A further spring element 10 can be arranged between the housing 7 and the housing wall 4. Due to the cyclic reciprocating movement along the y-direction of the movable element 3, the piston 1 is also moved cyclically back and forth relative to the housing 7. Depending on the chosen design, several fluid pumps can be provided.

[0042] Fig. 2 shows a schematic cross-sectional view of a partial section of Fig. 1, showing the fluid pump 6 in cross-section. A second end face 11 of the housing 7 rests against a bottom surface of the movable

[0043] Elements 3. The first end face 9 of the piston 8 sits on an inner surface of the housing wall 4. In the area of ​​the first end face 9 of the piston 8, fluid 12, for example oil, is located on the inner surface of the housing wall 4.

[0044] The housing 7 has a chamber 13 extending from a first end 14 of the housing 7 to a second end 11 of the housing. The chamber 13 has a pump section 15 extending from the first end 14 of the housing 7 towards the second end 11 of the housing 7. The pump section 15 has, for example, a cylindrical shape with a preferably constant cross-section. The pump section 15 transitions towards the second end 11 of the housing 7 preferably via a conically tapered end section 16, which narrows towards the second end 11 of the housing 7. The end section 16 constitutes a third section. Depending on the chosen embodiment, a separation can be made between the pump section 15 and the

[0045] End section 16 may have a tapered stage 17, which is formed, for example, in the form of a ring surface that extends transversely to the longitudinal extent of the R.411995

[0046] - 7 -

[0047] The chamber is arranged. The tapered stage 17 reduces the cross-section of chamber 13 to a smaller diameter in the form of a step.

[0048] Chamber 13 leads via the end section 16 into a further channel 18 of the movable element 3.

[0049] Depending on the chosen design, the chamber 13 can have a first section 29 in the region of the first end face 14 of the housing 7. The first section 29 has a cross-section that tapers conically towards the second end face of the housing, with the pump section 15 adjoining the first section 29, the first section being cold-formed.

[0050] In the selected embodiment, a plate valve 19 is arranged in the chamber 13, for example in the region of the annular surface 17. The plate valve 19 is designed to allow fluid to flow from the pump section 15 towards the further channel 18 and to prevent flow in the opposite direction.

[0051] Furthermore, a spring element 20 is provided in chamber 13, which preloads the piston towards the first end side 14 of the housing 7.

[0052] The piston 8 has a pumping surface 21, which is arranged opposite the first end face 9 of the piston 8 and constitutes a second end face of the piston. The pumping surface 21 delimits the chamber 13. The piston 8 also has a radially circumferential pumping section 22, which extends along the y-axis, is at least annular in shape, and seals against an inner wall 23 of the chamber 13. Furthermore, the piston 8 has a delivery line 24, which extends from the pumping surface 21 towards the first end face 9 of the piston 8. The delivery line 24 can, for example, be cylindrical and extend along the y-direction, and thus also along the direction of movement of the piston 8, through the entire piston 8.The piston 8 preferably has a recess 25 at its first end face 9, which is provided in the first end face 9 of the piston 8 and extends laterally from the delivery line 24 in an x-direction to an outer edge region of the piston 8. Depending on the selected embodiment, several recesses 25 and / or channels may be provided.

[0053] - 8 - be designed to allow the fluid 12 to flow into the delivery line 24 despite the contact of the first end face 9 of the piston 8 against the housing wall 4. For example, several recesses 25 are provided, each arranged at a 90° angle to one another, extending from the radial outer edge region of the piston into the delivery line 24. The recesses 25 are open in the y-direction on the first end face 9 of the piston 8. Preferably, the cross-section of the recesses 25 perpendicular to the flow direction of the fluid is larger than the cross-section of the delivery line 24 perpendicular to the flow direction of the fluid.

[0054] Furthermore, the piston 8 has an annular surface 26 between the sealing section 22 and the first end 9, over which the cross-section of the piston 8 transitions from the larger cross-section of the sealing section 22 to a smaller cross-section of a first end section 27 of the piston. The annular surface 26, which surrounds a central axis of the piston, extends transversely to the longitudinal extent of the piston 8. Thus, the annular surface 26 constitutes a retaining surface for the piston 8.

[0055] Fig. 2 shows the piston 8 in a position where the chamber 13 has its maximum filling volume. This is the situation where the movable element 3 is at its highest position in the y-direction. If the movable element 3 is now moved downwards towards the housing wall 4, the housing 7 shifts relative to the piston 8, which rests on the housing wall 4. During this movement, fluid 12, located in the chamber 13, is pumped through the pumping surface 21 of the piston 8, via the plate valve 19, and through the end section 16 into the further channel 18.

[0056] Fig. 3 shows a perspective partial sectional view of the fluid pump 6 of Fig. 2, with the piston 8 still in a pre-assembly position. The plate valve 19 is not shown. In the position shown, the plate valve 19 was first inserted into the chamber 13, then the spring element 20 was inserted into the chamber through the first end 14 of the housing 7. Finally, the piston 8 was inserted into the chamber 13, thereby pre-tensioning the spring element 20. R.411995

[0057] - 9 - In the area of ​​the first end side 14 of the housing 7, retaining tabs 25 are formed which, in the position shown, still extend along the y-axis.

[0058] The piston 8 is now permanently held in the chamber 13 by bending at least one, in particular both retaining tabs 25 in the direction of a central longitudinal axis of the chamber 13.

[0059] Fig. 4 shows a schematic and perspective sectional view of a corresponding arrangement of the fluid pump 6. The annular surface 26 of the piston 8 rests on the retaining tabs 25 due to the preload provided by the spring element 20; these tabs thus act as retaining surfaces and hold the piston in the chamber 13.

[0060] The formed retaining tabs 25 provide a means of securing the piston during assembly. Due to the cold forming process of the retaining tabs 25 during bending, from the initial position shown in Fig. 3 to the final position shown in Fig. 4, the bent retaining tabs 25 exhibit high stiffness and also a high surface hardness. This ensures that the piston 8 is securely held in the chamber by the retaining tabs 25, even under higher loads, i.e., particularly during vibrations or impacts on the annular surface 26.

Claims

R.411995 - 10 - Claims 1. Fluid pump (6), in particular an oil pump, with a housing (7), wherein a chamber (13) extends along a first direction from a first end (14) of the housing (7) to a second end (11) of the housing (7), wherein a piston (8) is movably arranged in a pumping section (15) of the chamber (13), wherein at least annular sealing section (22) of the piston (8) abuts an inner wall of the pumping section (15) of the chamber (13) in a sealing manner, wherein a delivery line (24) is formed in the piston (8), wherein the delivery line (24) extends from a first end (9) of the piston (8) to a second end (21) of the piston (8), wherein the first end (9) of the piston (8) is arranged outside the chamber (13), wherein the second end (21) of the piston (8) is arranged in the chamber (13), and wherein the delivery line (23) is designed to direct fluid from the first end (9) of the piston (8) into the chamber (13),wherein the piston (8) and / or the housing (7) are made of cold-formed metal.

2. Fluid pump according to claim 1, wherein the chamber (13) has a first section (29) at the first end side (14) of the housing (7), wherein the first section has a cross-section that is conically tapered towards the second end side (11) of the housing (7), wherein the pump section (15) is connected to the first section (29), wherein the first section (29) is cold formed.

3. Fluid pump according to one of the preceding claims, wherein the chamber (13) has a third section (16) extending from the pump section (15) towards the second end side, wherein the third section (16) has a cross-section that is conically tapered towards the second end side (11), wherein the third section (16) is cold formed. R.411995 - 11 - 4. Fluid pump according to claim 3, wherein the pump section (15) transitions via a tapering stage (17) into the third section (16), wherein the tapering stage (17) is an annular surface arranged transversely to the longitudinal extent of the chamber (13).

5. Fluid pump according to one of the preceding claims, wherein a spring element (20) is provided in the chamber (13) which biases the piston (8) towards the first end side (14) of the housing (7).

6. Fluid pump according to one of the preceding claims, wherein the housing (7) has in the first end side a retaining tab (28) bent towards a center of the chamber, the retaining tab (28) being a retaining surface which holds the piston (8) in the chamber (13).

7. Fluid pump according to one of the preceding claims, wherein the piston (8) has an annular surface (17) between the sealing section (22) and the first end side, over which the cross-section of the piston (8) transitions from the larger cross-section of the sealing section (22) to a smaller cross-section of a first end section (27), wherein the annular surface (17) is arranged transversely to the longitudinal extent of the piston (8), wherein the annular surface (17) represents a further retaining surface, wherein the further retaining surface abuts the retaining tab (28).

8. Fluid pump according to one of the preceding claims, wherein the delivery line (24) extends from the first end side (9) of the piston (8), wherein a recess (25) is provided in the first end side (9), wherein the recess (25) extends from a lateral edge of the piston (8) to the delivery line (24), wherein the recess facilitates the flow of fluid into the delivery line (24) when the first end side (9) of the piston (8) rests against a housing wall (4).

9. Fluid pump according to one of the preceding claims, wherein the housing consists of a cold-formed tubular blank, wherein in particular an entire inner surface and / or an entire outer surface of the blank is cold-formed. R.411995 - 12 - 10. Fluid pump according to one of the preceding claims, wherein the piston consists of a cold-formed tubular blank, wherein in particular an entire inner surface and / or an entire outer surface of the blank is cold-formed.

11. Method for manufacturing a fluid pump according to one of the preceding claims, wherein the piston and / or the housing are made of a cold-formed metal.

12. Method according to claim 11, wherein at least a partial section of the chamber of the housing was formed using a cold forming process.

13. Method according to claim 11 or 12, wherein at least a partial section of the piston was formed using a cold forming process.

14. Method according to any one of claims 11 to 13, wherein the piston is inserted into the chamber of the housing via the first end side of the housing, wherein a material section of the first end of the housing is subsequently bent towards a center of the chamber, wherein the material section constitutes a contact surface which holds the piston in the chamber.

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