ROTARY PUMP

Abstract

A rotary pump, the rotational direction of which can preferably be switched, featuring: a housing including a pump space featuring an inlet into a low-pressure region of the pump space for a fluid to be pumped and an outlet from a high-pressure region of the pump space for the fluid to be pumped; at least one rotor which forms delivery cells in the pump space; a bearing; and a sealing stay which axially faces the at least one rotor and separates the low-pressure region from the high-pressure region in the rotational direction of the at least one rotor; and featuring at least one lubricant feed, in the sealing stay, which feeds a fluid, as a lubricant, from at least one of the delivery cells to the bearing.

Claims

1. A rotary pump, the rotational direction of which can be switched, comprising: a) a housing comprising a pump space featuring an inlet into a low-pressure region of the pump space for a fluid to be pumped and an outlet from a high-pressure region of the pump space for the fluid to be pumped; b) at least one rotor which forms delivery cells in the pump space; c) at least one bearing; and d) at least one sealing stay which axially faces the at least one rotor and separates the low-pressure region from the high-pressure region in the rotational direction of the at least one rotor; and e) at least one lubricant feed, in the sealing stay, which feeds a fluid, as a lubricant, from at least one of the delivery cells to the bearing.

2. The rotary pump according to claim 1, wherein the housing comprises an inner circumferential wall which radially delineates the pump space and, together with the at least one rotor, forms a radial sealing gap in order to seal off adjacent delivery cells, wherein the radial sealing gap varies in size in the rotational direction of the rotor.

3. The rotary pump according to claim 2, wherein the radial sealing gap is smaller, in a circumferential region of the inner circumferential wall, which lies opposite the lubricant feed, than an average radial sealing gap.

4. The rotary pump according to claim 2, wherein the radial sealing gap in a circumferential region between the low-pressure region and the lubricant feed, and/or the radial sealing gap in a circumferential region between the high-pressure region and the lubricant feed, is larger than the radial sealing gap in the circumferential region opposite the lubricant feed.

5. The rotary pump according to claim 1, wherein the lubricant feed is a recess which extends in the radial direction from the bearing up to and into at least one delivery cell which passes over the recess.

6. The rotary pump according to claim 1, wherein the lubricant feed connects at least two adjacent delivery cells to each other in at least one position of the rotor.

7. The rotary pump according to claim 1, wherein the lubricant feed comprises at least one elongation which extends substantially in and/or counter to the rotational direction of the rotary pump, at or near an end which faces away from the bearing.

8. The rotary pump according to claim 1, wherein there is no position of the rotor at which the lubricant feed is short-circuited with the inlet into the pump space or the outlet from the pump space.

9. The rotary pump according to claim 1, wherein: the rotary pump comprises two rotors in the form of toothed wheels; the two toothed wheels mesh with each other in a driving stay; each of the rotors is assigned each of a bearing, a sealing stay and a lubricant feed; and the two lubricant feeds are connected to each other via the driving stay.

10. The rotary pump according to claim 1, further comprising an electric motor which drives the at least one rotor.

11. The rotary pump according to claim 1, wherein the rotary pump is an external-axle pump.

12. A rotary pump, a rotational direction of which can be switched, comprising: a) a housing comprising a pump space featuring an inlet into a low-pressure region of the pump space for a fluid to be pumped, an outlet from a high-pressure region of the pump space for the fluid to be pumped, and an inner circumferential wall which radially delineates the pump space; and b) at least one rotor which forms delivery cells in the pump space and, together with the inner circumferential wall, forms a radial sealing gap in order to seal off adjacent delivery cells, wherein c) the radial sealing gap varies in size in the rotational direction of the rotor.

13. The rotary pump according to claim 1, wherein the lubricant feed is a groove which extends in the radial direction from the bearing up to and into at least one delivery cell which passes over the recess.

14. The rotary pump according to claim 1, wherein the rotary pump is an externally toothed wheel pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the following, aspects of the invention are described in more detail on the basis of figures. The figures shoal example embodiments of a rotary pump, without thereby restricting aspects of the invention to the embodiments shown in the figures. Features essential to aspects of the invention which can only be gathered from the figures can advantageously develop the rotary pump of aspects of the invention, individually or in combination. The individual figures show:

[0035] FIGS. 1A and 1B an open pump housing, with and without toothed wheels, featuring a T-shaped lubricant feed;

[0036] FIG. 2 a partial exploded drawing of the pump in accordance with FIG. 1;

[0037] FIG. 3 an enlarged detail of the pump in accordance with FIG. 1;

[0038] FIGS. 4A and 4B an open pump housing, with and without toothed wheels, featuring a straight lubricant feed;

[0039] FIGS. 5A and 5B an open pump housing, with and without toothed wheels, featuring an L-shaped lubricant feed orientated counter to a rotational direction of the pump;

[0040] FIGS. 6A and 6B an open pump housing, with and without toothed wheels, featuring an L-shaped lubricant feed orientated in a rotational direction of the pump;

[0041] FIG. 7 an open pump housing, without toothed wheels, featuring an L-shaped lubricant feed and a connection which extends through the driving stay and fluidically connects bearings for the toothed wheel shafts to each other;

[0042] FIG. 8 an open pump housing of a rotary pump in which the lubricant feed has been omitted.

DETAILED DESCRIPTION OF THE INVENTION

[0043] FIGS. 1A to 7 show a rotary pump 1 of a motor vehicle. The rotary pump 1 can be driven electrically. The rotary pump 1 is embodied as an externally toothed wheel pump. It is embodied as a gear pump. The rotary pump 1 is provided in order to lubricate and/or cool an axle gear system of the motor vehicle. Additionally or alternatively, the rotary pump 1 can be provided in order to suction a fluid from a fluid sump of the motor vehicle. The motor vehicle is embodied as a motor vehicle which is driven by an electric motor. It is embodied as an electric vehicle. The fluid delivered by the rotary pump 1 is embodied as an oil.

[0044] FIGS. 1A and 1B show a view into the open rotary pump 1, in two depictions. The rotary pump 1 comprises two rotors 10, 11, which mesh with each other, and a housing 2. The left-hand depiction in FIG. 1A shows the open rotary pump 1 together with the rotors 10, 11 arranged in it. The right-hand depiction in FIG. 1B shows the open rotary pump 1 without the rotors 10, 11, wherein the rotors 10, 11 are indicated. An inner surface of an axial side wall of the rotary pump 1, for example a base or a cover, can be seen.

[0045] FIG. 2 shows the open rotary pump 1 in a perspective partial exploded representation. FIG. 3 shows an enlarged portion of the open rotary pump 1. The rotors 10, 11 are embodied as externally toothed wheels.

[0046] The rotors 10, 11 are each arranged on a rotor shaft or axle A0, A1. The rotors 10, 11 are each arranged, secured against rotating and shifting, on the rotor shaft or axle A0, A1. They are each pressed onto the rotor shaft or axle A0, A1. The rotor shafts or axles A0, A1 are rotatably mounted in the housing 2 by bearings 50, 51. The bearings 50, 51 are embodied as shaft bearings. They are embodied as slide bearings. The rotor 11 is embodied as a driven rotor 11 which outputs onto the rotor 10.

[0047] The housing 2 forms a pump space 7 featuring an inner circumferential wall 70, 71. The housing 2 has an inlet 4 into the pump space 7 and an outlet 3 from the pump space 7. The inner circumferential wall 70, 71 and the rotors 10, 11 together form a radial sealing gap which can be referred to as a tip clearance. The radial sealing gap extends from the inlet 4 into the pump space 7 up to the outlet 3 from the pump space 7 in relation to each rotor 10, 11. The radial sealing gap can at least partially also overlap the inlet 4 and/or outlet 3. In the rotary pump 1 of the example embodiment, the radial sealing gap overlaps the inlet 4 and the outlet 3, as can in particular be seen in the right-hand depiction. The rotors 10, 11 form delivery cells 8 in the pump space 7. The delivery cells 8 are delineated by the base, the cover, the respective inner circumferential wall 70, 71 and the respective rotor 10, 11.

[0048] The inlet 4 and outlet 3 are defined according to the rotational direction D of the rotary pump 1 which is indicated in the right-hand depiction. The rotary pump 1 can be a reversible rotary pump 1, in which the rotational direction D can be changed, whereby the inlet 4 becomes the outlet from the pump space 7, and the outlet 3 becomes the inlet into the pump space 7. The inlet 4 and the outlet 3 are separated from each other in the rotational direction D by sealing stays 90, 91, such that the medium or fluid delivered by the rotary pump 1 cannot flow directly from the inlet 4 to the outlet 3. The fluid is transported from the inlet 4 to the outlet 3 in the delivery cells 8.

[0049] A driving stay 9 is formed in the region in which the two rotors 10, 11 mesh with each other, and in which the teeth of the two rotors 10, 11 are in maximum engagement with each other, and likewise fluidically separates the inlet 4 from the outlet 3 and prevents the inlet 4 and outlet 3 from being fluidically short-circuited.

[0050] In order to lubricate the bearings 50, 51, lubricant feeds 60, 61 are formed in the sealing stays 90, 91, wherein the lubricant feeds 60, 61 supply the bearings 50, 51 with the fluid from the pump space 7. The lubricant feeds 60, 61 are embodied in the shape of a T. The free end or root of the lubricant feed 60, 61 emerges into the respective bearing 50, 51, wherein the lubricant feed 60, 61 extends radially far enough away from the bearing 50, 51 that the delivery cells 8 pass over at least the tip of the lubricant feed 60, 61 when the rotor 10, 11 is rotating. The tip of the lubricant feed 60, 61 connects two directly adjacent delivery cells 8 to each other. It is in principle conceivable for the lubricant feed 60, 61, in particular the tip of the lubricant feed 60, 61, to connect at least two non-adjacent delivery cells 8 to each other.

[0051] The inner circumferential wall 70, 71 respectively comprises a circumferential region 70r.sub.i, 71r.sub.i in which the radial sealing gap and/or tip clearance is smaller than in the rest of the circumferential region of the inner circumferential wall 70, 71. The circumferential regions 70r.sub.i, 71r.sub.i are formed in the inner circumferential wall 70, 71 at the point at which an imaginary radial elongation of the lubricant feeds 60, 61 would meet the inner circumferential wall 70, 71. An extent of the circumferential regions 70r.sub.i, 71r.sub.i in the rotational direction D of the rotary pump 1 is at least large enough that the circumferential region 70r.sub.i, 71r.sub.i completely covers at least one delivery cell 8 at its furthest extent in the rotational direction D of the rotary pump 1. In the example embodiment, the circumferential regions 70r.sub.i, 71r.sub.i extend over two adjacent delivery cells 8 when the rotor is correspondingly positioned, as can be seen in the right-hand depiction. These two delivery cells 8 are more effectively sealed off than the preceding and subsequent delivery cells 8 as viewed in the rotational direction D, due to the smaller radial sealing gap. A maximum extent of the circumferential regions 70r.sub.i, 71r.sub.i is determined by the inlet 4 and outlet 3 or, respectively, by the profile of the inner circumferential wall 70, 71, under the premise that the lubricant feed 60, 61 is not to be directly connected to the inlet 4 and/or outlet 3.

[0052] As can best be seen in FIG. 3, the inner circumferential wall 70, 71 in the circumferential regions 70r.sub.i, 71r.sub.i is part of a circle around the axle A0, A1 having a radius Ri which is smaller than a radius Ra in the circumferential region of the inner circumferential wall 70, 71 outside the circumferential regions 70r.sub.i, 71r.sub.i, wherein the radius Ri substantially corresponds to the radius of a circular circumference U which contacts all the radially outer ends of the delivery elements (in the example embodiment shown, the teeth of the rotor 10, 11), i.e. the radial sealing gap in the circumferential regions 70r.sub.i, 71r.sub.i is smaller than the rest of the sealing gap between the rotor 10, 11 and the inner circumferential wall 70, 71, whereby the delivery cells 8 are more effectively sealed off in these circumferential regions 70r.sub.i, 71r.sub.i. The fluid in the more effectively sealed-off delivery cells 8 is thus at a higher pressure, which is advantageous for pressing the fluid into the bearing 50, 51. In the example embodiment, the transitions in the sealing gap are not stepped; instead, the inner circumferential wall 70, 71 transitions into the circumferential regions 70r.sub.i, 71r.sub.i in a curve.

[0053] FIG. 2 shows the left-hand depiction from FIG. 1 in a partial exploded representation. The two rotor shafts or axles A0, A1 are missing, and the rotor 11 has been removed from the pump space 7, while the rotor 10 lies in the pump space 7. The inlet 4, the outlet 3 and the lubricant feeds 60, 61 are incorporated in the axial inner side of the housing 2 which faces the rotors 10, 11. Radially opposite the lubricant feeds 60, 61, the inner circumferential wall 70, 71 comprises a circumferential region 70r.sub.i, 71r.sub.i which protrudes radially inwards from the inner circumferential wall 70, 71. The inner circumferential wall 70, 71 and the circumferential regions 70r.sub.i, 71r.sub.i extend over their entire axial length substantially perpendicular to the axial end-facing side of the housing 2.

[0054] FIGS. 4A and 4B show a rotary pump 1 which is identical to the rotary pump 1 of FIGS. 1A and 1B except for the shape of the lubricant feed 60, 61 which in FIGS. 4A and 4B is formed as a straight line. The lubricant feed 60, 61 exhibits a width which substantially corresponds to a tooth width of a rotor 10, 11. The width of the lubricant feed 60, 61 can also be larger or smaller than the tooth width. If the width of the lubricant feed 60, 61 is larger than the tooth width, the lubricant feed 60, 61 connects two directly adjacent delivery cells 8 to each other.

[0055] FIGS. 5A-6B likewise show the rotary pump 1 as in FIGS. 1A and 1B, only the lubricant feeds 60, 61 are L-shaped in these figures and extend counter to the indicated rotational direction D of the rotor 10, 11 in FIG. 5B and in the indicated rotational direction D in FIG. 6B.

[0056] FIG. 7 shows a rotary pump 1 without the rotors 10, 11. Unlike the rotary pumps 1 in accordance with FIGS. 1A to 6B, the rotary pump 1 in accordance with FIG. 7 comprises a connection 12 which fluidically connects the bearings 50, 51 and the two lubricant feeds 60, 61 to each other via the driving stay 9.

[0057] FIG. 8 shows a rotary pump 1 which does not comprise any lubricant feeds. Aside from the lubricant feeds, the rotary pump 1 in FIG. 8 is identical to the rotary pump 1 shown in FIGS. 1A to 3. Unlike the rotary pump 1 in accordance with FIGS. 1A to 3, the rotary pump 1 in accordance with FIG. 8 lacks the lubricant feeds.

[0058] Like the rotary pump 1 of FIGS. 1A to 3, the inner circumferential wall 70, 71 of the rotary pump 1 in accordance with FIG. 8 respectively comprises a circumferential region 70r.sub.i, 71r.sub.i in which the radial sealing gap and/or tip clearance is smaller than in the rest of the circumferential region of the inner circumferential wall 70, 71. The circumferential regions 70r.sub.i, 71r.sub.i are formed in the inner circumferential wall 70, 71 between the inlet 4 and the outlet 3, substantially centrically as viewed in the rotational direction D. An extent of the circumferential regions 70r.sub.i, 71r.sub.i in the rotational direction D of the rotary pump 1 is at least large enough that the circumferential region 70r.sub.i, 71r.sub.i completely covers at least one delivery cell 8 at its furthest extent in the rotational direction D of the rotary pump 1. The circumferential regions 70r.sub.i, 71r.sub.i extend over two adjacent delivery cells 8 when the rotor is correspondingly positioned. These two delivery cells 8 are more effectively sealed off than the preceding and subsequent delivery cells 8 as viewed in the rotational direction D, due to the smaller radial sealing gap.

LIST OF REFERENCE SIGNS

[0059] 1 rotary pump [0060] 2 housing [0061] 3 outlet [0062] 4 inlet [0063] 50 bearing [0064] 51 bearing [0065] 60 lubricant feed [0066] 61 lubricant feed [0067] 7 pump space [0068] 70 inner circumferential wall [0069] 71 inner circumferential wall [0070] 70r.sub.i circumferential region [0071] 71r.sub.i circumferential region [0072] 8 delivery cell [0073] 9 driving stay [0074] 90 sealing stay [0075] 91 sealing stay [0076] 10 rotor [0077] 11 rotor [0078] 12 connection [0079] A0 axle [0080] A1 axle [0081] D rotational direction [0082] Ra radius [0083] Ri radius [0084] U circular circumference