DELIVERY ELEMENT FOR A ROTARY PUMP

Abstract

A delivery element for a rotary pump is proposed which is formed in one part from a metallic material, wherein the delivery element includes at least one first surface and at least one second surface which differ from each other, at least in regions, in at least one material property. A method for manufacturing a delivery element in accordance with the invention, a rotary pump including at least one delivery element in accordance with the invention, and the use of a delivery element in accordance with the invention in a rotary pump is also proposed.

Claims

1. A delivery element for a rotary pump, which is formed from a metallic material, wherein the delivery element comprises at least one first surface and at least one second surface which differ from each other, at least in regions, in at least one material property.

2. The delivery element according to claim 1, wherein the first surface and the second surface (7, 8) differ from each other, at least in regions, in at least one of a hardness, a density, and a compressive residual stress.

3. The delivery element according to claim 1, wherein the first surface and/or the second surface are formed by a surface layer which is at least one of harder, denser, and exhibits a greater compressive residual stress than a core region which lies beneath the surface layer.

4. The delivery element according to claim 3, wherein the surface layer forming the first surface is at least one of harder, denser, and exhibits a greater compressive residual stress, at least in regions, than the surface layer forming the second surface.

5. The delivery element according to claim 3, wherein the surface layer forming the second surface is thinner than the surface layer forming the first surface.

6. The delivery element according to claim 3, wherein the surface layer forming the second surface is at least partially ablated.

7. The delivery element according to claim 1, comprising: at least one curved surface, the curvature of which results at least substantially from a drawing process.

8. The delivery element according to claim 1, wherein the second surface is embodied as a housing sliding surface which is provided in order to slide on a delivery element running surface of a housing base or housing cover of the rotary pump.

9. The delivery element according to claim 1, wherein metallic material is a tempering steel.

10. The delivery element according to claim 1, wherein the metallic material is alloyed with chromium, molybdenum and vanadium.

11. The delivery element according to claim 1, wherein the delivery element is embodied as a vane for a vane cell pump.

12. A method for manufacturing a delivery element according to claim 1 for a rotary pump of a motor vehicle, wherein a delivery element blank formed from a metallic material is at least one of surface-hardened, surface-compacted, and surface-reinforced and the hardened, compacted and/or reinforced surface layer is then at least partially ablated on at least one surface of the delivery element blank.

13. The method according to claim 12, wherein the delivery element blank is ground in order to ablate the hardened, compacted and/or reinforced surface layer.

14. The method according to claim 12, wherein the delivery element blank is ground on its surfaces which define its main extent, in order to ablate the hardened, compacted and/or reinforced surface layer.

15. The method according to claim 12, wherein a process of grinding a curved surface of the delivery element blank is omitted.

16. A rotary vane cell pump for a motor vehicle, comprising at least one delivery element according to claim 1.

17. (canceled)

18. The delivery element according to claim 2, wherein the first surface and/or the second surface are formed by a surface layer which at least one of is harder, denser, and exhibits a greater compressive residual stress than a core region which lies beneath the surface layer.

19. The delivery element according to claim 4, wherein the surface layer forming the second surface is thinner than the surface layer forming the first surface.

20. The method according to claim 13, wherein the delivery element blank is ground on its surfaces which define its main extent, in order to ablate the hardened, compacted and/or reinforced surface layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other advantages follow from the following description of the figures. An example embodiment of the invention is shown in the figures. The figures, description and claims contain numerous features in combination. The person skilled in the art will also expediently consider the features individually and combine them to form other expedient combinations.

[0033] FIG. 1 shows a rotary pump with the housing cover disassembled, comprising multiple delivery elements in accordance with the invention;

[0034] FIG. 2 shows one of the delivery elements in accordance with the invention; and

[0035] FIG. 3 schematically shows a method sequence for manufacturing the delivery element in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0036] FIG. 1 shows a rotary pump 2 of a motor vehicle. The rotary pump 2 is provided in order to deliver an operational fluid. The operational fluid is embodied as a lubricant and/or coolant. In this example embodiment, the operational fluid is embodied as an engine lubricating oil. The rotary pump 2 is assigned to a combustion engine of the motor vehicle. The rotary pump 2 is embodied as a vane cell pump. The operational fluid can in principle also be embodied as an actuating means. The rotary pump 2 can in principle be assigned to a transmission of the motor vehicle.

[0037] In order to deliver the operational fluid, the rotary pump 2 comprises a delivery rotor 9 which rotates about a rotary axis 10 when the rotary pump 2 is in operation. The delivery rotor 9 comprises a rotor structure 11, which is central with respect to the rotary axis 10, and delivery elements 1 which are arranged in a distribution over the circumference of the rotor structure 11. The rotor structure 11 comprises multiple rotor slots in order to accommodate the delivery elements 1 in such a way that they can be shifted. One delivery element 1 is respectively arranged, such that it can be shifted, in each rotor slot.

[0038] In order to adjust a delivered amount of operational fluid while the rotary pump 2 is in operation, the rotary pump 2 comprises an adjustable setting element 12. The setting element 12 surrounds the delivery rotor 9. The setting element 12 comprises a delivery element running surface 16 which faces the delivery rotor 9. The delivery elements 1 contact and slide on the delivery element running surface 16. The delivery rotor 9 and the setting element 12 are arranged eccentrically with respect to each other. In order to adjust the eccentricity and therefore the delivered amount, the setting element 12 is arranged such that it can be pivoted. The setting element 12 is embodied as a setting ring. In order to adjust the eccentricity and therefore the delivered amount, the setting element 12 can in principle be arranged such that it can be axially shifted. The setting element 12 can in principle be embodied as a setting piston.

[0039] In order to shift the delivery elements 1 out of the rotor slot, perpendicularly with respect to the rotary axis 10, in accordance with the rotational position, the rotary pump 2 comprises a supporting element 15 which directly contacts the delivery elements 1. The supporting element 15 is provided in order to press the delivery elements 1 against the delivery element running surface 16 of the setting element 12. The supporting element 15 is embodied as a supporting ring.

[0040] The rotary pump 2 also comprises a housing 13. The delivery rotor 9 and the setting element 12 are arranged within the housing 13. The housing 13 comprises a housing base and a housing cover. Lateral walls axially protrude in one part out of the housing base in the direction of the housing cover with respect to the rotary axis 10. The housing cover is not shown in FIG. 1, such that the functional components of the rotary pump 2 are visible.

[0041] The housing base and the housing cover each comprise a delivery element running surface 16 which faces the delivery rotor 9. The delivery elements 1 contact and slide on the delivery element running surface 16 of the housing base and the delivery element running surface 16 of the housing cover. The housing base, the housing cover and the setting element 12 enclose a delivery chamber within the setting element 12, in which the operational fluid is delivered from a suction side to a pressure side by the delivery elements 1 while the rotary pump 2 is in operation.

[0042] The housing 13 and the setting element 12 enclose at least one hydraulic setting chamber 17 outside the setting element 12. A hydraulic pressure, which acts on the setting element 12 in order to adjust the eccentricity and therefore the delivered amount, can be built up in the at least one setting chamber 17 while the rotary pump 2 is in operation. The pressure in the at least one setting chamber 17 acts in the direction of less eccentricity and therefore a lower delivered amount.

[0043] In order to restore the setting element 12, the rotary pump 2 comprises a spring element 14 which is functionally connected to the setting element 12. The spring element 14 acts counter to the hydraulic pressure in the at least one setting chamber 17 and therefore counter to a setting force which acts on the setting element 12 and results from the pressure in the at least one setting chamber 17. The spring element 14 is embodied as a restoring spring or a regulating spring. It acts as a pressure spring. In this example embodiment, the spring element 14 is embodied as a helical spring.

[0044] The delivery elements 1 are embodied as single-part vanes. The delivery elements 1 are formed entirely from a metallic material. The delivery elements 1 are produced from a single metallic material. They are formed from a tempering steel. The material of the delivery elements 1 is a nitriding steel alloyed with chromium, molybdenum and vanadium. In this example embodiment, the delivery element 1 is made of the material 31CrMoV9. The delivery elements 1 are embodied similarly to each other, for which reason only one of the delivery elements 1 is described in more detail in the following. The delivery elements 1 do not comprise a coating produced by being applied and are in this sense uncoated.

[0045] FIG. 2 shows the delivery element 1 in a perspective view. The delivery element 1 comprises six surfaces 3, 4, 5, 6, 7, 8. Each two of the surfaces 3, 4, 5, 6, 7, 8 are orientated in parallel with each other. Each two surfaces 3, 4, 5, 6, 7, 8 which are orientated in parallel with each other respectively face away from each other. The two surfaces 3, 4 which are orientated in parallel with each other exhibit the largest area as compared to the other surfaces 5, 6, 7, 8. The two surfaces 5, 6 which are orientated in parallel with each other are embodied as curved surfaces. The two surfaces 5, 6 are convex. The curvature of the surfaces 5, 6 results substantially from a drawing process. In the drawing process, the delivery element 1 can be plastically deformed, thus creating the surfaces 5, 6 embodied as drawn surfaces. The two surfaces 7, 8 which are orientated in parallel with each other are embodied as axially facing surfaces. The delivery element 1 exhibits a main extent 19 which is orientated in parallel with the rotary axis 10 when the delivery element 1 is fitted in the rotary pump 2. The main extent 19 is the largest extent of the delivery element 1. The two surfaces 7, 8 define the main extent 19 of the delivery element 1. A distance between the two surfaces 7, 8 which are orientated in parallel with each other corresponds to the main extent 19. The four surfaces 3, 4, 5, 6 together form a shell surface of the delivery element 1. The shell surface extends around a centre axis 18 of the delivery element 1 which is orientated in parallel with the main extent 19. The two surfaces 7, 8 form a base surface and covering surface, respectively. The base surface and covering surface are orientated perpendicularly with respect to the centre axis 18. The surfaces 3, 4, 5, 6 are each orientated in parallel with the main extent 19. The surfaces 7, 8 are each orientated perpendicularly with respect to the main extent 19. The delivery element 1 is embodied as a cuboid.

[0046] The surfaces 3, 4, 5, 6, 7, 8 are each embodied as a friction surface or a sliding surface. The two surfaces 3, 4 are each embodied as a rotor sliding surface. They are provided in order to slide on a lateral sliding surface of the rotor slot when arranged in the rotor slot of the rotor structure 11. When the delivery element 1 is fitted, the two surfaces 3, 4 point in the circumferential direction of the rotor structure 11.

[0047] The surface 5 is embodied as a supporting surface. It contacts the supporting element 15 when the delivery element 1 is fitted. The delivery element 1 is supported on the supporting element 15 at the surface 5. When the delivery element 1 is fitted, the surface 5 points in the radial direction of the rotor structure 11. The surface 5 points perpendicularly with respect to the rotary axis 10 when the delivery element 1 is fitted. It faces the rotary axis 10.

[0048] The surface 6 is embodied as a setting element sliding surface. It contacts the setting element 12 when the delivery element 1 is fitted. The surface 6 is provided in order to slide on the delivery element running surface 16 of the setting element 12 when the delivery element 1 is fitted. When the delivery element 1 is fitted, the surface 6 points in the radial direction of the rotor structure 11. The surface 6 points perpendicularly with respect to the rotary axis 10 when the delivery element 1 is fitted. It faces away from the rotary axis 10.

[0049] The two surfaces 7, 8 are each embodied as a housing sliding surface. The surface 7 contacts the housing cover when the delivery element 1 is fitted. It is provided in order to slide on the delivery element running surface of the housing cover when the delivery element 1 is fitted. When the delivery element 1 is fitted, the surface 7 points in the axial direction of the rotor structure 11. The surface 7 points in parallel with the rotary axis 10 when the delivery element 1 is fitted. It faces the housing cover.

[0050] The surface 8 contacts the housing base when the delivery element 1 is fitted. It is provided in order to slide on the delivery element running surface of the housing base when the delivery element 1 is fitted. When the delivery element 1 is fitted, the surface 8 points in the axial direction of the rotor structure 11. The surface 8 points in parallel with the rotary axis 10 when the delivery element 1 is fitted. It faces the housing base.

[0051] The delivery element 1 is surface-hardened. The delivery element 1 harder on the surfaces 3, 4, 5, 6, 7, 8 than in its core. The surfaces 3, 4, 5, 6, 7, 8 are each formed by a surface layer which is harder than a core region of the delivery element 1 which lies beneath the surface layer. The delivery element 1 is nitrided. It is gas-nitrided. The surfaces 3, 4, 5, 6 differ from the surfaces 7, 8 in a physical material property. The physical material property by which the surfaces 3, 4, 5, 6 differ from the surfaces 7, 8 is embodied as a hardness, in particular a Vickers hardness. The surfaces 3, 4, 5, 6 are harder than the surfaces 7, 8. The shell surface of the delivery element 1 is harder than the base surface and/or covering surface of the delivery element 1. The surfaces 3, 4, 5, 6 exhibit a Vickers hardness HV10 of more than 600. The surfaces 7, 8 exhibit a Vickers hardness HV10 of more than 300. The Vickers hardness HV10 of the surfaces 7, 8 is less than 600, in particular less than 500. The core and the surface layers are made of the same metallic material. The delivery element 1 can also be surface-compacted, in particular when the delivery element 1 is embodied as a powder-metallurgical delivery element. It is also conceivable for the delivery element 1 to exhibit induced compressive residual stresses on at least one of the surfaces 3, 4, 5, 6, 7, 8, whereby the surfaces 3, 4, 5, 6, 7, 8 exhibit greater compressive residual stresses than the core.

[0052] The surface layer forming the surfaces 3, 4, 5, 6 is harder than the surface layer forming the surfaces 7, 8. The surface layer forming the surfaces 7, 8 is partially ablated. The surface layer forming the surfaces 7, 8 is thinner than the surface layer forming the surfaces 3, 4, 5, 6.

[0053] The nitriding hardness depth (NHD) on the surfaces 7, 8 is respectively less than the nitriding hardness depth (NHD) on the surfaces 3, 4, 5, 6. The surfaces 3, 4, 5, 6 each comprise a connecting layer formed by diffusing nitrogen or carbon into it (ε and γ′ iron nitrides). The surfaces 7, 8 lack such a connecting layer formed by diffusing nitrogen or carbon into it (ε and γ′ iron nitrides). The connecting layer formed by diffusing nitrogen or carbon into it (ε and γ′ iron nitrides) is mechanically ablated on the surfaces 7, 8.

[0054] FIG. 3 schematically shows a method sequence for manufacturing the delivery element 1. The method for manufacturing the delivery element 1 comprises at least three method steps 20, 26, 27. The method advantageously comprises at least one other method step 21, 22, 23, 24, 25. The at least one method step 21, 22, 23, 24, 25 is performed after method step 20 and before method steps 26, 27. In this example embodiment, the method for manufacturing the delivery element 1 comprises multiple method steps 21, 22, 23, 24, 25 between method steps 20, 26, 27. It comprises at least five method steps 21, 22, 23, 24, 25 between method steps 20, 26, 27.

[0055] In method step 20, a delivery element blank is separated from a metallic material profile at the surfaces 7, 8 by way of a separating process. The separating process in method step 20 is embodied as an adiabatic separating process. Following method step 20, the delivery element blank is slide-ground in method step 21. Following method step 21, the delivery element blank is tempered in method step 22. Following method step 22, the delivery element blank is ground on its surfaces 3, 4 in method step 23. Following method step 23, the delivery element blank is slide-ground and demagnetised in method step 24. Following method step 24, the delivery element blank is washed in method step 25.

[0056] Following method step 25, the delivery element blank is surface-hardened in method step 26, thus creating a hardened surface layer on the surfaces 3, 4, 5, 6, 7, 8. Beneath the hardened surface layer, the delivery element blank comprises a core region which is softer than the surface layer. In method step 26, the delivery element blank is gas-nitrided for the purpose of surface-hardening.

[0057] Following method step 26, the hardened surface layer is mechanically ablated partially, on the two surfaces 7, 8 only, in method step 27. The hardened delivery element blank is ground on the surfaces 7, 8 in method step 27, in order to ablate the hardened surface layer. In method step 27, the hardened delivery element blank is ground on its surfaces 7, 8 which define its main extent 19, thus partially ablating the hardened surface layer on the surfaces 7, 8. In method step 27, the nitriding hardness depth (NHD) on the surfaces 7, 8 is reduced by ablating the hardened surface layer. By ablating the hardened surface layer, a connecting layer formed by diffusing nitrogen or carbon into it (ε and γ′ iron nitrides) is mechanically ablated on the surfaces 7, 8.

[0058] Following method step 27, the delivery element 1 is in principle ready for use. A process of grinding, in particular radius grinding, the curved surfaces 5, 6 of the delivery element blank is omitted. At least one other method step, such as for example a gauging process, can in principle follow method step 27.

LIST OF REFERENCE SIGNS

[0059] 1 delivery element [0060] 2 rotary pump [0061] 3 surface [0062] 4 surface [0063] 5 surface [0064] 6 surface [0065] 7 surface [0066] 8 surface [0067] 9 delivery rotor [0068] 10 rotary axis [0069] 11 rotor structure [0070] 12 setting element [0071] 13 housing [0072] 14 spring element [0073] 15 supporting element [0074] 16 delivery element running surface [0075] 17 setting chamber [0076] 18 centre axis [0077] 19 main extent [0078] 20 method step [0079] 21 method step [0080] 22 method step [0081] 23 method step [0082] 24 method step [0083] 25 method step [0084] 26 method step [0085] 27 method step