Rotary pump having an adjustable specific delivery volume and a pressure equalization surface

Abstract

A rotary pump includes: a housing featuring a housing inlet and a low-pressure space on a low-pressure side of the pump and featuring a housing outlet and a high-pressure space on a high-pressure side of the pump; a delivery chamber; a delivery rotor in the delivery chamber; a setting structure which can be moved in a first setting direction and, counter to the first setting direction, in a second setting direction in order to perform a setting movement which adjusts the specific delivery volume of the rotary pump; and at least a first setting chamber for charging the setting structure with a setting pressure which acts in the second setting direction, wherein the fluid pressure in the high-pressure space acts on a pressure equalization surface on the outer circumference of the setting structure resulting in an external additional force which acts on the setting structure in the first setting direction.

Claims

1. A rotary pump having an adjustable specific delivery volume the rotary pump comprising: (a) a housing featuring a housing inlet and a low-pressure space, connected to the housing inlet, on a low-pressure side of the pump and featuring a housing outlet and a high-pressure space, connected to the housing outlet, on a high-pressure side of the pump; (b) a delivery chamber into which a delivery chamber inlet connected to the low-pressure space opens on the low-pressure side and into which a delivery chamber outlet connected to the high-pressure space opens on the high-pressure side; (c) a delivery rotor which is rotatable about an axis of rotation in the delivery chamber; (d) a setting structure which is movable back and forth in a first setting direction and, counter to the first setting direction, in a second setting direction in order to perform a setting movement which adjusts the adjustable specific delivery volume of the rotary pump; and (e) at least a first setting chamber for charging the setting structure with a setting pressure of a setting fluid which acts in the second setting direction, (f) wherein the fluid pressure in the high-pressure space acts on a pressure equalization surface on an outer circumference of the setting structure, and the pressure equalization surface has a pressure surface asymmetry, resulting in an external additional force which acts on the setting structure in the first setting direction, and (g) wherein the external additional force corresponds to an equalizing force which acts counter to an internal force.

2. The rotary pump according to claim 1, wherein the high-pressure space is provided downstream of the delivery chamber outlet and upstream of the housing outlet in the housing.

3. The rotary pump according to claim 1, wherein at least most of the fluid which is delivered from the delivery chamber through the delivery chamber outlet flows into the high-pressure space and flows off out of the high-pressure space via the housing outlet, such that at least most of the fluid flows off out of the pump from the delivery chamber via the high-pressure space.

4. The rotary pump according to claim 1, wherein a normal vector of the pressure equalization surface has a setting direction component parallel to the setting directions as a whole, which is greater than zero, and a transverse component transverse to the setting directions as a whole, and the transverse component is more than three times or more than five times or more than ten times as large as the setting direction component.

5. The rotary pump according to claim 1, wherein the high-pressure space is connected in fluid communication to the delivery chamber via the setting structure.

6. The rotary pump according to claim 1, wherein the pressure equalization surface is a movable delineating wall of the high-pressure space, and a pressure prevailing in the high-pressure space acts on the setting structure via the pressure equalization surface.

7. The rotary pump according to claim 1, wherein a restoring element exerts a spring force which acts in the first setting direction on the setting structure.

8. The rotary pump according to claim 1, wherein the setting movement of the setting structure in the first setting direction increases the adjustable specific delivery volume, and the setting movement of the setting structure in the second setting direction reduces the adjustable specific delivery volume.

9. The rotary pump according to claim 1, wherein the fluid situated in the delivery chamber exerts a resultant internal force on the setting structure which acts in the second setting direction.

10. The rotary pump according to claim 1, wherein the setting structure is movable linearly back and forth in the first setting direction and in the second setting direction.

11. The rotary pump according to claim 1, wherein the rotary pump has another, second setting chamber for charging the setting structure with a setting pressure of a setting fluid which acts in one of the two setting directions, wherein the second setting chamber is provided for charging the setting structure with a setting pressure of the setting fluid.

12. The rotary pump according to claim 1, wherein: a normal vector of the pressure equalization surface has a setting direction component parallel to the setting directions as a whole, which is greater than zero; a normal vector of a pressure setting surface of the first setting chamber has a setting direction component parallel to the setting directions as a whole; and the setting direction component of the pressure setting surface of the first setting chamber is at least three times or at least five times or at least ten times greater than the setting direction component of the pressure equalization surface.

13. The rotary pump according to claim 1, wherein: the outer circumference of the setting structure has a first sliding surface, for forming a first sealing gap with the housing, and a second sliding surface for forming a second sealing gap with the housing; the pressure equalization surface extends in the circumferential direction from the first sealing gap up to the second sealing gap; and the first and second sliding surfaces are offset relative to one another, transversely with respect to the first and second setting directions, such that a normal vector of the pressure equalization surface for generating the external additional force points counter to the first setting direction.

14. The rotary pump according to claim 13, wherein the transverse offset of the first and second sliding surfaces provides an effective pressure equalization surface, on which a pressure prevailing in the housing on the high-pressure side acts in the first setting direction in order to generate the external additional force.

15. A rotary pump having an adjustable specific delivery volume the rotary pump comprising: (a) a housing featuring a housing inlet and a low-pressure space, connected to the housing inlet, on a low-pressure side of the pump and featuring a housing outlet and a high-pressure space, connected to the housing outlet, on a high-pressure side of the pump; (b) a delivery chamber into which a delivery chamber inlet connected to the low-pressure space opens on the low-pressure side and into which a delivery chamber outlet connected to the high-pressure space opens on the high-pressure side; (c) a delivery rotor which is rotatable about an axis of rotation in the delivery chamber; (d) a setting structure which is movable back and forth in a first setting direction and, counter to the first setting direction, in a second setting direction in order to perform a setting movement which adjusts the adjustable specific delivery volume of the rotary pump; and (e) at least a first setting chamber for charging the setting structure with a setting pressure of a setting fluid which acts in the second setting direction, (f) wherein the fluid pressure in the high-pressure space acts on a pressure equalization surface on an outer circumference of the setting structure, and the pressure equalization surface has a pressure surface asymmetry, resulting in an external additional force which acts on the setting structure in the first setting direction, and (g) wherein a normal vector of the pressure equalization surface has a setting direction component parallel to the setting directions as a whole, which is greater than zero, and a transverse component transverse to the setting directions as a whole, and the transverse component is more than three times or more than five times or more than ten times as large as the setting direction component.

16. The rotary pump according to claim 15, wherein: the normal vector of the pressure equalization surface has a setting direction component parallel to the setting directions as a whole, which is greater than zero; a normal vector of a pressure setting surface of the first setting chamber has a setting direction component parallel to the setting directions as a whole; and the setting direction component of the pressure setting surface of the first setting chamber (22) is at least three times or at least five times or at least ten times greater than the setting direction component of the pressure equalization surface.

17. The rotary pump according to claim 15, wherein: the outer circumference of the setting structure has a first sliding surface, for forming a first sealing gap with the housing, and a second sliding surface for forming a second sealing gap with the housing; the pressure equalization surface extends in the circumferential direction from the first sealing gap up to the second sealing gap; and the first and second sliding surfaces are offset relative to one another, transversely with respect to the first and second setting directions, such that the normal vector of the pressure equalization surface for generating the external additional force points counter to the first setting direction.

18. The rotary pump according to claim 17, wherein the transverse offset of the first and second sliding surfaces provides an effective pressure equalization surface, on which a pressure prevailing in the housing on the high-pressure side acts in the first setting direction in order to generate the external additional force.

19. A rotary pump having an adjustable specific delivery volume the rotary pump comprising: (a) a housing featuring a housing inlet and a low-pressure space, connected to the housing inlet, on a low-pressure side of the pump and featuring a housing outlet and a high-pressure space, connected to the housing outlet, on a high-pressure side of the pump; (b) a delivery chamber into which a delivery chamber inlet connected to the low-pressure space opens on the low-pressure side and into which a delivery chamber outlet connected to the high-pressure space opens on the high-pressure side; (c) a delivery rotor which is rotatable about an axis of rotation in the delivery chamber; (d) a setting structure which is movable back and forth in a first setting direction and, counter to the first setting direction, in a second setting direction in order to perform a setting movement which adjusts the adjustable specific delivery volume of the rotary pump; and (e) at least a first setting chamber for charging the setting structure with a setting pressure of a setting fluid which acts in the second setting direction, (f) wherein the fluid pressure in the high-pressure space acts on a pressure equalization surface on an outer circumference of the setting structure, and the pressure equalization surface has a pressure surface asymmetry, resulting in an external additional force which acts on the setting structure in the first setting direction, and (g) wherein: a normal vector of the pressure equalization surface has a setting direction component parallel to the setting directions as a whole, which is greater than zero; a normal vector of a pressure setting surface of the first setting chamber has a setting direction component parallel to the setting directions as a whole; and the setting direction component of the pressure setting surface of the first setting chamber is at least three times or at least five times or at least ten times greater than the setting direction component of the pressure equalization surface.

20. The rotary pump according to claim 19, wherein: the outer circumference of the setting structure has a first sliding surface, for forming a first sealing gap with the housing, and a second sliding surface for forming a second sealing gap with the housing; the pressure equalization surface extends in the circumferential direction from the first sealing gap up to the second sealing gap; and the first and second sliding surfaces are offset relative to one another, transversely with respect to the first and second setting directions, such that the normal vector of the pressure equalization surface for generating the external additional force points counter to the first setting direction.

21. A rotary pump having an adjustable specific delivery volume the rotary pump comprising: (a) a housing featuring a housing inlet and a low-pressure space, connected to the housing inlet, on a low-pressure side of the pump and featuring a housing outlet and a high-pressure space, connected to the housing outlet, on a high-pressure side of the pump; (b) a delivery chamber into which a delivery chamber inlet connected to the low-pressure space opens on the low-pressure side and into which a delivery chamber outlet connected to the high-pressure space opens on the high-pressure side; (c) a delivery rotor which is rotatable about an axis of rotation in the delivery chamber; (d) a setting structure which is movable back and forth in a first setting direction and, counter to the first setting direction, in a second setting direction in order to perform a setting movement which adjusts the adjustable specific delivery volume of the rotary pump; and (e) at least a first setting chamber for charging the setting structure with a setting pressure of a setting fluid which acts in the second setting direction, (f) wherein the fluid pressure in the high-pressure space acts on a pressure equalization surface on an outer circumference of the setting structure, and the pressure equalization surface has a pressure surface asymmetry, resulting in an external additional force which acts on the setting structure in the first setting direction, (g) wherein i. the outer circumference of the setting structure has a first sliding surface, for forming a first sealing gap with the housing, and a second sliding surface for forming a second sealing gap with the housing; ii. the pressure equalization surface extends in the circumferential direction from the first sealing gap up to the second sealing gap; and iii. the first and second sliding surfaces are offset relative to one another, transversely with respect to the first and second setting directions, iv. such that a normal vector of the pressure equalization surface for generating the external additional force points counter to the first setting direction, and (h) wherein the transverse offset of the first and second sliding surfaces provides an effective pressure equalization surface, on which a pressure prevailing in the housing on the high-pressure side acts in the first setting direction in order to generate the external additional force.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below on the basis of example embodiments. Features disclosed by the example embodiments advantageously develop the subject-matter of the claims, the aspects and also the embodiments described above. There is shown:

(2) FIG. 1 a rotary pump having an adjustable delivery volume and a pressure equalization surface; and

(3) FIG. 2 the operating principle of the pressure equalization surface.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows a rotary pump having an adjustable delivery volume. The rotary pump is a vane cell pump. The rotary pump comprises a housing 1 featuring a housing inlet and a housing outlet for a fluid, for example lubricating oil or gear oil. The rotary pump also comprises a delivery rotor featuring a rotor 2, which can be rotated in the delivery chamber, and vanes which are movably guided by the rotor 2. The vanes are supported on the radially outer side on an inner contour of a setting structure 3 and sub-divide the delivery chamber into a plurality of delivery cells. The setting structure 3 delineates the delivery chamber radially outwards and serves to adjust the delivery volume.

(5) The setting structure 3 is mounted such that it can move back and forth, for example linearly, in a first setting direction and a second setting direction. The first setting direction and the second setting direction are indicated in FIG. 2 by a double-headed arrow in the upper region of the image. The outer circumference of the setting structure 3 has a first sliding surface 3b, a second sliding surface 3c, a third sliding surface 3d, a fourth slide surface 3e and a fifth sliding surface 3f. The sliding surfaces 3b to 3f are part of the outer circumferential surface of the setting structure 3. They can be formed directly by the setting structure 3 or by sealing elements which are arranged at the corresponding locations on the outer circumference of the setting structure 3 and/or in the complementary surfaces on the housing 1. The sliding surfaces 3b to 3f extend parallel to the first setting direction and second setting direction. The housing 1 guides the setting structure 3 in a sliding guide contact in the region of the sliding surfaces 3b to 3f. The first setting direction and the second setting direction are determined by the sliding surfaces 3b to 3f in the sliding guide contact.

(6) A first setting chamber 22 and a second setting chamber 23 are formed in the housing 1. The first setting chamber 22 and the second setting chamber 23 are charged with pressure, wherein the first setting chamber 22 is permanently connected in fluid communication to the high-pressure side of the rotary pump, while the second setting chamber 23 can be selectively connected in fluid communication to the high-pressure side or the low-pressure side of the rotary pump via a control valve. The setting pressure prevailing in the first setting chamber 22 acts on the setting structure 3 in the setting direction. The setting pressure acting on the setting surface 22a generates a setting force in the setting direction. The setting surface 22a is part of the outer circumferential surface of the setting structure 3 and forms a movable wall of the first setting chamber 22. A restoring force acts in a restoring direction, counter to the setting force. The restoring force is generated by a restoring element 4, for example a restoring spring, which acts on the setting structure 3, wherein the restoring element 4 acts in the direction of increasing the delivery volume.

(7) The restoring element 4 is arranged in a restoring chamber 12 which is preferably part of the low-pressure side of the pump, more specifically a low-pressure space 11 of the housing 1. The low-pressure space 11 is permanently connected fluidically to the housing inlet. The low-pressure space 11 is fluidically separated from the second setting chamber 23 in a circumferential direction by the sealing gap formed between the housing 1 and the setting structure 3 in the region of the sliding surface 3e. The low-pressure space 11 extends in the other circumferential direction up to the sealing gap formed in the region of the second sliding surface 3c. The restoring chamber 12 is attached to the low-pressure space 11 and is thus part of the low-pressure space 11. The sealing gap formed in the region of the second sliding surface 3c separates the high-pressure space 21 from the restoring chamber 12 and thus from the low-pressure space 11 of the housing 1. In modifications, the restoring chamber 12 can be permanently connected to the high-pressure side of the pump or selectively connected to and separated from the high-pressure side of the pump in order to relieve the restoring element 12 and/or to enable additional ways of adjusting the specific delivery volume.

(8) If the restoring force and the setting force are in force equilibrium, the setting structure 3 is not moved. If the restoring force is greater than the setting force, the setting structure 3 is moved in the restoring direction. The restoring direction is referred to in the following as the “first setting direction”. The setting direction in which the pressure prevailing in the first setting chamber 22 acts on the setting structure 3 is referred to in the following as the “second setting direction”. If the setting force is greater than the restoring force, the setting structure 3 is moved in the second setting direction, against the restoring force of the restoring element 4, and the delivery volume is reduced, i.e. the pump is governed.

(9) If the second setting chamber 23 is charged via the control valve with fluid from the high-pressure side of the pump, the fluid acts on the setting surface 23a, which forms a movable wall of the second setting chamber 23, and likewise generates a setting force in the second setting direction. The first setting chamber 22 and the second setting chamber 23 are arranged next to one another in the circumferential direction of the setting structure 3 and fluidically separated from one another by the sealing gap formed between the housing 1 and the setting structure 3 in the region of the third sliding surface 3d. The setting chambers 22 and 23 can in particular, as in the example embodiment, be arranged directly next to one another, separated from one another only by the sealing gap at 3d.

(10) The rotary pump has a high-pressure space 21. The high-pressure space 21 is connected in fluid communication to the delivery chamber via the delivery chamber outlet 20. Although the delivery chamber outlet 20 is preferably formed by a pressure pocket in the housing 1 and a cavity in the setting structure 3 on the side of the setting structure 3 opposite the pressure pocket, the delivery chamber outlet 20 in FIGS. 1 and 2 is shown only as a pressure pocket in the housing. The explanations immediately above also apply analogously to the delivery chamber inlet 10. The high-pressure space 21 is separated from the delivery chamber only by the setting structure 3, as is preferred, and forms an antechamber to the housing outlet of the pump (not shown).

(11) The high-pressure space 21 connects the high-pressure side of the delivery chamber to the housing outlet. When the pump is in operation, at least some of the fluid on the high-pressure side of the pump is discharged via the high-pressure space 21. Preferably, at least most of the fluid is discharged via the high-pressure space 21. The delivery chamber outlet is particularly preferably connected to the housing outlet via the high-pressure space 21 only, such that the entire delivery flow is discharged via the high-pressure space 21 when the pump is in operation.

(12) The high-pressure space 21 is delineated inter alia by a pressure equalization surface 3a. The pressure equalization surface 3a is a circumferential portion of the outer circumferential surface of the setting structure 3 and forms a movable wall of the high-pressure space 21. The pressure equalization surface 3 exhibits a pressure surface asymmetry within the high-pressure space 21. The pressure surface asymmetry arises from an offset which the sliding surfaces 3b and 3c have relative to one another in a transverse direction with respect to the first and second setting direction of the setting structure 3. The sliding surfaces 3b and 3c are for example formed in the shape of projecting shoulders on the setting structure 3. The transverse offset provides the pressure equalization surface 3a with an asymmetry with respect to the first and second setting directions. The pressure equalization surface 3a has a remaining differential area in relation to the first and second setting directions, which is referred to in the following as the effective pressure equalization surface 3a′ (FIG. 2). The effective pressure equalization surface 3a′ lies between the sliding surfaces 3b and 3c as viewed in the circumferential direction. As is preferred, the sliding surfaces 3b and 3c delineate the pressure equalization surface 3a and therefore its effective pressure equalization surface 3a′ in the circumferential direction. The pressure prevailing in the high-pressure space 21 generates a setting force, which acts on the setting structure 3 in the first setting direction, in accordance with the size of the transverse offset and by association in accordance with the size of the differential area and/or effective pressure equalization surface 3a′.

(13) In the example embodiment, the setting structure 3 is broadly circular. The sliding surfaces 3b and 3c of the projecting shoulders are also offset transversely with respect to one another. The outer circumferential surface of the setting structure 3 describes a circular arc, which includes the equalization surface 3a, between the sliding surfaces 3b and 3c in the circumferential direction in the high-pressure space 21. The profile of the circular arc between the sliding surfaces 3b and 3c is however only one example of this outer circumferential portion of the setting structure 3.

(14) If the sliding surfaces 3b and 3c (cf. FIG. 2) are notionally extended in the first setting direction and the second setting direction, the circumferential portion of the setting structure 3 enclosed by the parallel lines gives the effective pressure equalization surface 3a′. The effective pressure equalization surface 3a′ is the projection of the enclosed circumferential portion in the first setting direction. The distance between the two parallel lines corresponds to the width of the effective pressure equalization surface 3a′ as measured transversely with respect to the first and second setting directions.

(15) The rotary pump has a low-pressure space 11 which is connected to the delivery chamber inlet 10 and the housing inlet (not shown). The low-pressure space 11 is preferably connected in fluid communication to the restoring chamber 12, such that the restoring chamber 12 and the low-pressure space 11 have the same pressure level.

(16) The principle of the external additional force F.sub.a will be explained in the following on the basis of FIG. 2. For a better overview, the rotor and the vanes are not shown in FIG. 2.

(17) An internal force is generated by the pressure conditions within the delivery chamber. The internal force has a force component F.sub.i in the second setting direction. The internal force can also have a force component orthogonal to the second setting direction, in this case preferably in the direction of the high-pressure space 21, since this at least partially compensates for the force exerted on the setting structure 3 by the pressure in the high-pressure space 21. The force component pointing in the second setting direction is referred to in the following as the internal force F.sub.i. If the internal force also has a force component transverse to the first setting direction, both the force composed of the two force components and the force component acting in the second setting direction are referred to as the “internal force F.sub.i”. The fluid pressure prevailing in the high-pressure space 21 acts on the outer circumferential surface of the setting structure 3, i.e. on the pressure equalization surface 3a. At each point on the pressure equalization surface 3a, a force thus arises which is perpendicular to the outer circumferential surface at this point. Since only forces acting in the first setting direction and in the second setting direction are relevant to an unintentional change in the specific delivery volume, only the resultants of these forces are indicated in FIG. 2.

(18) As already described at the beginning, the two sliding surfaces 3b and 3c of the setting structure 3 are offset with respect to one another, transversely with respect to the first and second setting directions. If the sliding surfaces 3b and 3c are notionally extended in the first setting direction and the second setting direction, the projection of the circumferential portion of the setting structure 3 enclosed by the parallel lines 3b′ and 3c′ corresponds to the effective pressure equalization surface 3a′, wherein the distance between the two parallel lines corresponds to the width of the effective pressure equalization surface.

(19) The fluid pressure which acts on the part of the pressure equalization surface 3a to the left of the parallel line 3b′ generates forces whose force components in the first setting direction are equal in size to the force components in the second setting direction. These force components thus compensate for one another reciprocally. By contrast, the forces which act on the part of the effective pressure equalization surface 3a to the right of the parallel line 3b′ generate a resultant force in the first setting direction. This resultant force is proportional to the size of the effective pressure equalization surface 3a′ and serves to compensate for the internal force F.sub.i. The resultant force generated by the effective pressure equalization surface 3a serves as an external additional force F.sub.a which is directed oppositely to the internal force F.sub.i. The pump and its setting structure 3 can in particular be designed such that the internal force F.sub.i and the external additional force F.sub.a are equal in size and cancel one another out. The additional external force F.sub.a thus acts as an equalizing force for the internal force F.sub.i.