ROTARY PUMP COMPRISING A SETTING STRUCTURE SPRING HAVING AN OFFSET LINE OF ACTION

Abstract

A rotary pump including: a pump housing including a delivery chamber, having an inlet and an outlet for a fluid; a delivery member which can be rotated about a rotational axis in the delivery chamber in order to deliver the fluid; a setting structure which can be moved translationally back and forth in the pump housing relative to the delivery member in and counter to a setting direction in order to adjust the delivery volume of the rotary pump; a setting device for generating a setting force which acts on the setting structure in the setting direction; a restoring spring for exerting a restoring force which acts on the setting structure counter to the setting direction; and an additional spring for exerting an additional force which acts on the setting structure in or counter to the setting direction.

Claims

1.-17. (canceled)

18. A rotary pump having an adjustable delivery volume, comprising: 1.1. a pump housing comprising a delivery chamber, a low-pressure region of which has a delivery chamber inlet for a fluid to be delivered, and a high-pressure region of which has a delivery chamber outlet for the fluid; 1.2. a delivery member which can be rotated about a rotational axis in the delivery chamber in order to deliver the fluid; 1.3. a setting structure which can be moved translationally back and forth in the pump housing relative to the delivery member in and counter to a setting direction in order to adjust the delivery volume of the rotary pump, and which exhibits an inner contour which delineates the delivery chamber radially on the outside; 1.4. a setting device for generating a setting force which acts on the setting structure in the setting direction; 1.5. a restoring spring for exerting a restoring force which acts on the setting structure counter to the setting direction; and 1.6. an additional spring for exerting an additional force which acts on the setting structure in or counter to the setting direction, 1.7. wherein the additional force crosses the rotational axis at a lever arm distance.

19. The rotary pump according to claim 18, wherein the additional force and/or the restoring force act(s) on the setting structure secantially with respect to the inner contour.

20. The rotary pump according to claim 18, wherein: the restoring force and the additional force generate a resultant external force; the resultant external force crosses the rotational axis at a lever arm distance.

21. The rotary pump according to claim 18, wherein the additional force acts counter to the setting direction on a portion of the setting structure surrounding the high-pressure region of the delivery chamber, or wherein the additional force acts in the setting direction on a portion of the setting structure surrounding the low-pressure region of the delivery chamber.

22. The rotary pump according to claim 18, wherein the additional force generates a torque which acts on the setting structure and is directed oppositely to the rotary direction of the delivery member.

23. The rotary pump according to claim 18, wherein the restoring force and the additional force generate a resultant external force, and the external force generates a torque which acts on the setting structure and is directed oppositely to the rotary direction of the delivery member.

24. The rotary pump according to claim 18, wherein the restoring force of the restoring spring which acts on the setting structure and/or the additional force of the additional spring which acts on the setting structure act parallel to the setting direction or at an acute angle of less than 10° to the setting direction only.

25. The rotary pump according to claim 18, wherein the restoring force and the additional force act on the setting structure at a spring force distance from each other which is orthogonal with respect to the setting direction.

26. The rotary pump according to claim 25, wherein the spring force distance is equal to or greater than the lever arm distance.

27. The rotary pump according to claim 18, wherein the restoring force acts on the setting structure radially with respect to the rotational axis or crosses the rotational axis at a distance which is less than the lever arm distance at which the additional force crosses the rotational axis.

28. The rotary pump according to claim 18, wherein the restoring force is greater than the additional force.

29. The rotary pump according to claim 18, wherein the restoring force and the additional force differ in magnitude in one or more different positions which the setting structure can assume within the scope of its mobility in and counter to the setting direction.

30. The rotary pump according to claim 18, wherein the restoring force and the additional force generate a resultant external force which acts on the setting structure counter to the setting direction.

31. The rotary pump according to claim 30, wherein the setting structure comprises an abutment which comes into contact with a surface of the pump housing when the delivery volume of the rotary pump is at its maximum, and wherein the line of action of the resultant external force passes through the abutment.

32. The rotary pump according to claim 30, wherein the resultant external force crosses the rotational axis at a distance, and the resultant external force acts counter to the setting direction on a portion of the setting structure surrounding the high-pressure region of the delivery chamber.

33. The rotary pump according to claim 30, wherein the resultant external force acts on the setting structure secantially with respect to the inner contour, and the resultant external force generates a torque which acts on the setting structure and is directed oppositely to the rotary direction of the delivery member when the pump is operating normally.

34. The rotary pump according to claim 18, wherein the setting structure comprises an abutment which comes into contact with a surface of the pump housing when the delivery volume of the rotary pump is at its maximum, and wherein the abutment is formed between the line of action of the restoring force and the line of action of the additional force.

35. The rotary pump according to claim 20, wherein the lever arm distance is at most 30%, or at most 20%, of an inner width of the inner contour as measured radially with respect to the rotational axis.

36. The rotary pump according to claim 35, wherein the inner width is orientated orthogonally with respect to the setting direction.

37. The rotary pump according to claim 29, wherein the restoring force and the additional force differ in magnitude in each position of the setting structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0108] 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 and also the embodiments described above. There is shown:

[0109] FIG. 1 a cross-section of a rotary pump having an adjustable delivery volume in a first example embodiment;

[0110] FIG. 2 a cross-section of a rotary pump having an adjustable delivery volume in a second example embodiment;

[0111] FIG. 3 a schematic drawing of the rotary pump of the second example embodiment;

[0112] FIG. 4 a schematic drawing of the rotary pump of the first example embodiment;

[0113] FIG. 5 a schematic drawing of a rotary pump in a third example embodiment;

[0114] FIG. 6 a schematic drawing of a rotary pump in accordance with a fourth example embodiment;

[0115] FIG. 7 a schematic drawing of a rotary pump in accordance with a fifth example embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0116] FIG. 1 and FIG. 4 show a rotary pump having an adjustable delivery volume in accordance with a first example embodiment. The rotary pump includes a pump housing 1 comprising a delivery chamber, a low-pressure region of which has a delivery chamber inlet 2 for a fluid to be delivered, and a high-pressure region of which has a delivery chamber outlet 3 for the fluid. A delivery member which can be rotated about a rotational axis R in order to deliver the fluid is arranged in the delivery chamber. The delivery member is formed by a delivery rotor and multiple vanes mounted in the delivery rotor such that they can slide.

[0117] For adjusting the delivery volume of the rotary pump, the pump housing 1 of the rotary pump includes a setting structure 10 which can be translationally moved back and forth relative to the delivery member in and counter to a setting direction and which has an inner contour I which delineates the delivery chamber radially on the outside. The setting structure 10 is formed by a setting ring which encloses the delivery chamber radially on the outside, and the inner contour I of which is formed to be circular. The setting structure 10 does not delineate the delivery chamber in the axial direction.

[0118] A setting device 30, 31 for generating a setting force F.sub.S which acts on the setting structure 10 in the setting direction is formed in the pump housing 1. The setting device 30, 31 is formed by a fluid setting chamber 30 and an abutment 31. The fluid setting chamber 30 is preferably connected permanently or selectively to the high-pressure region of the delivery chamber, such that the fluid can act on a setting surface of the setting structure 10. The fluid can be diverted from the delivery chamber outlet 3 of the delivery chamber and fed to the fluid setting chamber 30 directly or for example via a control valve. The setting force F.sub.S acts on the setting structure 10 in the setting direction. Moving the setting structure 10 in the setting direction throttles the pump, i.e. reduces the delivery volume. Accordingly, moving the setting structure 10 counter to the setting direction increases the delivery volume, wherein the setting force F.sub.S results from the fluid acting on the setting structure 10 and located in the fluid setting chamber 30, and is indicated as a resultant force in FIG. 1.

[0119] As can be seen from FIG. 1, the resultant setting force F.sub.S crosses the rotational axis R of the rotary pump at a distance. This generates a torque which acts on the setting structure 10 in the rotational direction. In addition to the torque generated by the setting force F.sub.S, a frictional moment which corresponds to a torque acting in the rotational direction of the delivery member additionally acts on the setting structure 10 when the delivery member is rotated. Alternatively, the resultant setting force F.sub.S can act on the setting structure 10 radially in relation to the inner contour I, as indicated in the schematic drawing in FIG. 4. In this case, the resultant setting force F.sub.S does not generate a torque which acts on the setting structure 10.

[0120] The rotary pump also includes a restoring spring 11 for exerting a restoring force F.sub.R, which acts on the setting structure 10 counter to the setting direction, and an additional spring 12 for exerting an additional force F.sub.A which likewise acts on the setting structure 10 counter to the setting direction. The restoring spring 11 and the additional spring 12 act on the setting structure 10 on a side of the setting structure 10 radially opposite the fluid setting chamber 30 in the setting direction.

[0121] The restoring spring 11 is arranged in a restoring space 20. In accordance with the example embodiment of FIG. 1, the restoring space 20 is formed radially opposite the fluid setting chamber 30 in the setting direction. The fluid setting chamber 30 and the restoring space 20 are fluidically separated from each other, i.e. fluid from the fluid setting chamber 30 cannot flow into the restoring space 20 and vice versa. The restoring space 20 is preferably free of pressure. The restoring space 20 is preferably connected to the low-pressure region of the rotary pump. In addition to the restoring spring 11, the additional spring 12 is also arranged in the restoring space 20.

[0122] The restoring spring 11 and the additional spring 12 are each formed by a helical compression spring. In accordance with the present example embodiment, the restoring spring 11 and the additional spring 12 are cylindrical helical compression springs. The person skilled in the art will be aware that this is merely an example embodiment and that the restoring spring 11 and the additional spring 12 can also be formed by other types of spring, for example disc springs, hollow rubber springs or the like.

[0123] The restoring spring 11 has a first spring constant, and the additional spring 12 has a second spring constant. The first spring constant of the restoring spring 11 and the second spring constant of the additional spring 12 preferably differ in magnitude. In the present example embodiment, the second spring constant of the additional spring 12 is preferably less than the first spring constant of the restoring spring 11. Here, too, it will be self-evident to the person skilled in the art to appropriately adapt the first spring constant and/or the second spring constant.

[0124] The restoring spring 11 exerts a restoring force F.sub.R acting counter to the setting direction on the setting structure 10. In accordance with the first example embodiment, the restoring force F.sub.R acts on the setting structure 10 radially in relation to the inner contour I of the setting structure 10, i.e. the restoring force F.sub.R crosses the rotational axis R at a distance which is equal to zero.

[0125] The additional spring 12 exerts the additional force F.sub.A acting counter to the setting direction on the setting structure 10. In accordance with the first example embodiment of FIG. 1 and FIG. 4, the additional force F.sub.A crosses the rotational axis R at a lever arm distance d; in particular, the additional force F.sub.A acts secantially on the setting structure 10, wherein the additional force F.sub.A acts on a portion of the setting structure 10 surrounding the high-pressure region of the delivery chamber.

[0126] As can be seen in FIG. 4 in particular, the inner contour I of the setting structure 10 has an inner width A, which is divided by the bisector B transversely with respect to the setting direction into two portions of equal length. The additional force F.sub.A is spaced from the bisector B by the lever arm distance d. In accordance with the first example embodiment, the line of action of the restoring spring 11 overlaps with the bisector B.

[0127] Due to the lever arm distance d, the additional force F.sub.A generates a torque which acts on the setting structure 10 counter to the rotational direction of the delivery member. The torque generated by the additional force F.sub.A preferably at least partially compensates for the torques which are generated by the setting force F.sub.S and the frictional moment and which act on the setting structure 10 in the rotational direction.

[0128] The restoring force F.sub.R and the additional force F.sub.A are introduced into the setting structure 10 at a spring force distance D from each other which is orthogonal with respect to the setting direction. In accordance with the example embodiment of FIG. 1 and FIG. 4, respectively, the spring force distance D is the same as the lever arm distance d at which the additional force F.sub.A crosses the rotational axis R. The additional force F.sub.A acts on a portion of the setting structure 10 surrounding the high-pressure region of the delivery chamber.

[0129] The restoring force F.sub.R and/or the additional force F.sub.A then act on the setting structure 10 parallel to the setting direction only, i.e. the restoring force F.sub.R corresponds to the resultant spring force exerted by the restoring spring 11 and/or the additional force F.sub.A corresponds to the resultant spring force exerted by the additional spring 12.

[0130] The restoring force F.sub.R and the additional force F.sub.A together generate a resultant external force F.sub.E which crosses the rotational axis R at a lever arm distance d.sub.E. The lever arm distance d.sub.E of the resultant external force F.sub.E is at most 30%, preferably at most 20%, of the inner width A of the inner contour I as measured radially with respect to the rotational axis R. The resultant external force F.sub.E acts on a portion of the setting structure 10 surrounding the high-pressure region of the delivery chamber. The resultant external force F.sub.E thus generates a torque which acts on the setting structure 10 counter to the rotational direction of the rotary pump when the pump is operating normally.

[0131] In the region of the fluid setting chamber 30, the setting structure 10 has an abutment 31 which comes into contact with a surface of the pump housing 1 when the delivery volume of the rotary pump is at its maximum. The abutment 31 thus limits the translational movement of the setting structure 10 counter to the setting direction.

[0132] The line of action of the resultant external force F.sub.E passes, in particular centrally, through the abutment 31 of the setting structure 10. The abutment 31 is also formed between the line of action of the restoring force F.sub.R and the line of action of the additional force F.sub.A. The setting force F.sub.S preferably does not act on the abutment 31, i.e. the line of action of the setting force F.sub.S does not pass through the abutment 31.

[0133] In addition to the abutment 31, the setting structure 10 has a protrusion 21 which is formed on the side of the setting structure 10 axially opposite the abutment 31. The protrusion 21 lies opposite the abutment 31 in the setting direction, preferably exactly opposite the abutment 31. The protrusion 21 is formed centrally between the restoring spring 11 and the additional spring 12, i.e. the protrusion 21 is formed centrally between the line of action of the restoring force F.sub.R and the line of action of the additional force F.sub.A. The line of action of the resultant external force F.sub.E also passes through the protrusion 21.

[0134] The protrusion 21 serves to mount the restoring spring 11 and the additional spring 12, such that the end of the restoring spring 11 which rests against the setting structure 10 and/or the end of the additional spring 12 which rests against the setting structure 10 is/are restricted in its/their movement transverse to the setting direction. The protrusion 21 also serves to separate the two spring ends transversely with respect to the setting direction.

[0135] FIG. 2 shows a cross-section of a rotary pump having an adjustable delivery volume in a second example embodiment. FIG. 3 shows a schematic drawing of the rotary pump of the second example embodiment. The rotary pump in accordance with the second example embodiment differs only immaterially from the example embodiment in accordance with FIG. 1. In the following, therefore, only the differences between the first example embodiment and the second example embodiment shall be discussed. Statements relating to the first example embodiment also apply to the example embodiment in accordance with FIG. 2, providing they do not contradict the second example embodiment.

[0136] The rotary pump in accordance with FIG. 2 differs from the example embodiment of FIG. 1 in particular in that the rotary pump comprises only a restoring spring 11 for exerting a restoring force F.sub.R which acts on the setting structure 10 counter to the setting direction, i.e. unlike the rotary pump of the first example embodiment, the rotary pump in accordance with FIG. 2 does not include an additional spring 12.

[0137] The restoring spring 11 generates a restoring force F.sub.R which crosses the rotational axis R at a distance d.sub.R, wherein the restoring force F.sub.R acts on the setting structure 10 secantially with respect to the inner contour I, i.e. the line of action of the restoring force F.sub.R is a secant in relation to the inner contour I of the setting structure 10, i.e. contrary to the first example embodiment, the restoring force F.sub.R does not act on the setting structure 10 radially in relation to the inner contour I of the setting structure 10.

[0138] The distance d.sub.R is at most 30%, preferably 20%, of the inner width A of the inner contour I as measured radially with respect to the rotational axis R, wherein the inner width A is measured orthogonally with respect to the setting direction. The restoring spring 11 in accordance with the second example embodiment thus performs the function of the additional spring 12 and at the same time the function of the restoring spring 11 of the first example embodiment. In other words, the restoring force F.sub.R corresponds to the resultant external force F.sub.E of the first example embodiment, i.e. what has been said regarding the resultant external force F.sub.E applies equally to the restoring force F.sub.R of the second example embodiment.

[0139] The restoring force F.sub.R preferably acts on the portion of the setting structure 10 surrounding the high-pressure region of the delivery chamber. The restoring force F.sub.R thus generates a torque which acts on the setting structure 10 counter to the rotational direction of the rotary pump when the pump is operating normally.

[0140] The rotary pump in accordance with the second example embodiment likewise has an abutment 31 which comes into contact with a surface of the pump housing 1 when the delivery volume of the rotary pump is at its maximum. The abutment 31 thus limits the translational movement of the setting structure 10 counter to the setting direction.

[0141] Contrary to the line of action of the resultant external force F.sub.E in accordance with the first example embodiment, however, the line of action of the restoring force F.sub.R does not pass through the abutment 31 of the setting structure 10. The setting force F.sub.S in accordance with FIG. 2 likewise acts on the setting structure 10 radially in relation to the inner contour I of the setting structure 10, i.e. the setting force F.sub.S crosses the rotational axis R at a lever arm distance which is equal to zero.

[0142] The example embodiment of FIG. 2 otherwise corresponds to the example embodiment of FIG. 1.

[0143] FIG. 5 shows a schematic drawing of a rotary pump in a third example embodiment. Since the third example embodiment differs only immaterially from the first example embodiment, only the differences will substantially be discussed. Statements made with respect to the first example embodiment also apply to the third example embodiment, providing they do not contradict the third example embodiment.

[0144] The rotary pump in accordance with the third example embodiment substantially corresponds to the first example embodiment, i.e. in accordance with the third example embodiment, the rotary pump has a restoring spring 11 and an additional spring 12, wherein the restoring spring 11 generates a restoring force F.sub.R which acts on the setting structure 10 counter to the setting direction, and the additional spring 12 generates an additional force F.sub.A which together with the restoring force F.sub.R acts on the setting structure 10 counter to the setting direction.

[0145] The example embodiment in accordance with FIG. 5 differs from the example embodiment in accordance with FIG. 1 and FIG. 4 in that the restoring force F.sub.R does not act on the setting structure 10 radially in relation to the inner contour I. Contrary to the first example embodiment, the restoring force F.sub.R acts secantially. The restoring force F.sub.R crosses the rotational axis R at a distance d.sub.R.

[0146] The distance d.sub.R at which the restoring force F.sub.R crosses the rotational axis R is less than the lever arm distance d at which the additional force F.sub.A crosses the rotational axis R. The restoring force F.sub.R and the additional force F.sub.A are introduced into the setting structure 10 at a spring force distance D, wherein the spring force distance D results from the sum of the lever arm distance d and the distance d.sub.R. The restoring force F.sub.R and the additional force F.sub.A act on the setting structure 10 orthogonally with respect to the setting direction and on different sides of the bisector B.

[0147] In accordance with the example embodiment of FIG. 5, the restoring force F.sub.R preferably acts on a portion of the setting structure 10 surrounding the low-pressure region of the delivery chamber, i.e. the restoring force F.sub.R generates a torque which acts on the setting structure 10 in the rotational direction of the delivery member. Like the additional force F.sub.A of the first example embodiment, the additional force F.sub.A of the third example embodiment generates a torque which acts on the setting structure 10 counter to the rotational direction. The torque which this additional force F.sub.A generates is greater than the torque which the restoring force F.sub.R generates, such that as a result, the restoring force F.sub.R and the additional force F.sub.A generate a resultant torque which acts on the setting structure 10 counter to the rotational direction of the delivery member.

[0148] In other words, the restoring force F.sub.R and the additional force F.sub.A generate a resultant external force F.sub.E which acts secantially on the setting structure 10. The lever arm distance d at which the additional force F.sub.A crosses the rotational axis R and the distance d.sub.R at which the restoring force F.sub.R crosses the rotational axis R, as well as the additional force F.sub.A and the restoring force F.sub.R, are set such that the resultant external Force F.sub.E preferably acts on a portion of the setting structure 10 surrounding the high-pressure region of the delivery chamber, i.e. the resultant external force F.sub.E generates a torque which acts on the setting structure 10 counter to the rotational direction of the delivery member.

[0149] FIG. 6 shows a schematic drawing of a fourth example embodiment. Since the fourth example embodiment differs only immaterially from the first and third example embodiments, only the differences shall substantially be discussed. Statements made with respect to the first and third example embodiments also apply to the fourth example embodiment, providing they do not contradict it.

[0150] In accordance with the fourth example embodiment, the restoring force F.sub.R likewise crosses the rotational axis R at a distance d.sub.R, but the restoring force F.sub.R together with the additional force F.sub.A preferably acts on a portion of the setting structure 10 surrounding the high-pressure region of the delivery chamber. The restoring force F.sub.R and the additional force F.sub.A act on the setting structure 10 orthogonally with respect to the setting direction and on the same side of the bisector B.

[0151] The distance d.sub.R at which the restoring force F.sub.R crosses the rotational axis R, plus the spring force distance D, equals the lever arm distance d at which the additional force F.sub.A crosses the rotational axis R.

[0152] FIG. 7 shows a schematic drawing of a fifth example embodiment. Since the fifth example embodiment differs from the first example embodiment only with regard to the additional spring 12 and the additional force F.sub.A, only the differences shall substantially be discussed. Statements made with respect to the first example embodiment also apply to the fifth example embodiment, providing they do not contradict it.

[0153] Contrary to the example embodiment in accordance with FIG. 1, the additional spring 12 is arranged on the side of the setting structure 10 radially opposite the restoring spring 11. The additional spring 12 generates an additional force F.sub.A which acts on the setting structure 10 in the setting direction, i.e. contrary to the other example embodiments, the additional force F.sub.A acts in the same direction as the setting force F.sub.S.

[0154] The overall setting force F.sub.S is composed, so to speak, of multiple force components, wherein one force component is formed by the setting force F.sub.S and a second force component is formed by the additional force F.sub.A, wherein both force components act permanently on the setting structure 10.

[0155] The additional force F.sub.A crosses the rotational axis R at a lever arm distance d, wherein the additional force F.sub.A preferably acts on a portion of the setting structure 10 surrounding the low-pressure region of the delivery chamber. In this way, the additional force F.sub.A generates a torque which acts on the setting structure 10 in the opposite direction to the torque of the delivery member generated by friction and counter to the rotational direction.

[0156] The setting force F.sub.S of the setting device 30, 31 and the additional force F.sub.A of the additional spring 12 preferably act on the setting structure 10 parallel to the setting direction or at an acute angle of less than 10° to the setting direction.

REFERENCE SIGNS

[0157] 1 pump housing

[0158] 2 delivery chamber inlet

[0159] 3 delivery chamber outlet

[0160] 10 setting structure

[0161] 11 restoring spring

[0162] 12 additional spring

[0163] 20 restoring space

[0164] 21 protrusion

[0165] 30 fluid setting chamber

[0166] 31 abutment

[0167] A inner width

[0168] B bisector

[0169] D spring force distance

[0170] d lever arm distance of the additional force

[0171] d.sub.E lever arm distance of the resultant external force

[0172] d.sub.R distance of the restoring force

[0173] F.sub.E resultant external force

[0174] F.sub.S setting force

[0175] F.sub.R restoring force

[0176] F.sub.A additional force

[0177] I inner contour

[0178] R rotational axis