VANE PUMP FEATURING FLUID LUBRICATION FOR AN IMPELLER

Abstract

A vane pump includes: a housing with a first end-facing wall and a second end-facing wall which delineate a delivery chamber on one end-facing side each, and with a circumferential wall which extends around the delivery chamber; a rotor which can be rotated about a rotational axis in the delivery chamber and which forms a first axial gap with the first end-facing wall and a second axial gap with the second end-facing wall; multiple vanes which can be moved back and forth in guide slots of the rotor, wherein the guide slots have sub-vane regions which are connected to the high-pressure side of the delivery chamber in order to apply pressure to the underside of the respective vanes; and a collecting structure for collecting fluid via the first axial gap.

Claims

1.-15. (canceled)

16. A vane pump for supplying an assembly with a fluid, the vane pump comprising: a pump housing having a first end-facing wall and a second end-facing wall which delineate a delivery chamber of the vane pump on one end-facing side each, and a circumferential wall which extends around the delivery chamber; an inlet for the fluid on a low-pressure side of the delivery chamber and an outlet for the fluid on a high-pressure side of the delivery chamber; a rotor which can be rotated about a rotational axis in the delivery chamber, and which forms a first axial gap with the first end-facing wall of the housing on a first end-facing side and a second axial gap with the second end-facing wall of the housing on the other, second end-facing side; multiple vanes which can be moved back and forth in guide slots of the rotor, wherein the guide slots have radially inner sub-vane regions which are connected to the high-pressure side of the delivery chamber at least when the vanes are passing through the high-pressure side, in order to apply pressure to the underside of the respective vanes; and a collecting structure which extends around the rotational axis in the first axial gap in order to collect fluid which enters the collecting structure via the first axial gap, wherein the collecting structure comprises one or more recesses formed on the first end-facing wall of the housing and/or the first end-facing side of the rotor, radially between the rotational axis and the sub-vane regions, and the first axial gap forms an outer sealing gap, radially between the sub-vane regions and the collecting structure, which continuously encircles the rotational axis without interruption.

17. The vane pump according to claim 16, wherein the first axial gap forms an inner sealing gap, circumferentially and continuously around the rotational axis without interruption, which the collecting structure surrounds.

18. The vane pump according to claim 16, wherein the collecting structure is a blind groove.

19. The vane pump according to claim 16, wherein the collecting structure is fluidically isolated such that fluid can only enter the collecting structure via leakage.

20. The vane pump according to claim 16, wherein the outer sealing gap and/or the inner sealing gap, if provided, fluidically separates the collecting structure from the high-pressure side and/or the low-pressure side of the vane pump, such that fluid can only enter and/or exit the collecting structure due to leakage via the respective sealing gap.

21. The vane pump according to claim 16, wherein the collecting structure is continuously circumferential.

22. The vane pump according to claim 16, wherein the outer sealing gap has an axial width W.sub.1a and/or the inner sealing gap, if provided, has an axial width W.sub.1b, the collecting structure has a maximum axial depth T, and one or more of the following relationships is/are met: $T5W_{1a}\mathrm{or}T10W_{1a}\mathrm{or}T20W_{1a}$ $\mathrm{and}/\mathrm{or}$ $T5W_{1b}\mathrm{or}T10W_{1b}\mathrm{or}T20W_{1b}.$

23. The vane pump according to claim 16, wherein the outer sealing gap has a radial width B.sub.1a and/or the inner sealing gap, if provided, has a radial width B.sub.1b, the collecting structure has a maximum axial depth T, and one or more of the following relationships is/are met: $B_{1a}T\mathrm{or}{B}_{1a}2T\mathrm{or}{B}_{1a}3T$ $\mathrm{and}/\mathrm{or}$ $B_{1b}T\mathrm{or}{B}_{1b}2T\mathrm{or}{B}_{1b}3T.$

24. The vane pump according to claim 16, wherein: the first end-facing wall of the housing has a radially outer sealing surface and a radially inner sealing surface; the first end-facing side of the rotor has a radially outer sealing surface and a radially inner sealing surface; the outer sealing surface of the end-facing wall and the outer sealing surface of the rotor continuously encircle the rotational axis without interruption axially opposite each other and form the outer sealing gap which is circumferentially contained over 360 and surrounds the collecting structure; and the inner sealing surface of the end-facing wall and the inner sealing surface of the rotor continuously encircle the rotational axis without interruption axially opposite each other and form an inner sealing gap which is circumferentially contained over 360 and which the collecting structure surrounds.

25. The vane pump according to claim 16, wherein the respective recess of the collecting structure has a round or U-shaped or V-shaped profile.

26. The vane pump according to claim 16, wherein the rotor is axially mounted in a suspended manner between the first end-facing wall of the housing and the second end-facing wall of the housing.

27. The vane pump according to claim 16, comprising a drive shaft which is mounted such that it can be rotated about the rotational axis and to which the rotor is connected in a way which transmits torque, wherein the collecting structure extends around the drive shaft, and the first axial gap forms an inner sealing gap which encircles the drive shaft, radially between the rotational axis and the collecting structure, continuously without interruption.

28. The vane pump according to claim 27, wherein the drive shaft protrudes into the first end-facing wall of the housing, and the inner sealing gap adjoins the drive shaft on the radially inner side and the collecting structure on the radially outer side.

29. The vane pump according to claim 16, wherein the vane pump has a first flow comprising the inlet and the outlet and, following the first flow in the rotational direction of the rotor, a second flow comprising another inlet and another outlet, such that when the rotor is rotated, a portion of the fluid is delivered in the first flow and another portion of the fluid is delivered in the second flow.

30. The vane pump according to claim 16, wherein one or more supply pockets which open into the first axial gap and are connected to the high-pressure side or the low-pressure side of the vane pump is/are provided on the first end-facing wall of the housing, axially facing the sub-vane regions, and the outer sealing gap continuously encircles the rotational axis, radially between the collecting structure and the supply pocket(s).

31. The vane pump according to claim 16, wherein the collecting structure is a blind groove which encircles the rotational axis continuously.

32. The vane pump according to claim 16, wherein the collecting structure is fluidically isolated such that fluid can only enter the collecting structure via leakage and also only exit the collecting structure via leakage.

33. The vane pump according to claim 16, wherein the collecting structure is continuously circumferential and is or comprises an annular groove which continuously encircles the rotational axis.

34. The vane pump according to claim 24, wherein the outer sealing gap surrounds and radially adjoins the collecting structure.

35. The vane pump according to claim 24, wherein the inner sealing gap radially adjoins the collecting structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] An example embodiment of the invention is described below on the basis of figures. Features disclosed by the figures, each individually and in any combination of features, advantageously develop the claims, the aspects and the embodiments described above. There is shown:

[0091] FIG. 1 a vane pump comprising a fluid collecting structure in accordance with the invention, in a longitudinal section;

[0092] FIG. 2 the vane pump, not yet fully assembled, in a plan view;

[0093] FIG. 3 an end-facing wall of the housing of the vane pump, in a plan view;

[0094] FIG. 4 the end-facing wall of the housing, in the longitudinal section C-C of FIG. 3;

[0095] FIG. 5 a portion of the vane pump featuring the collecting structure;

[0096] FIG. 6 the end-facing wall of the housing again, in the plan view of FIG. 3;

[0097] FIG. 7 a collecting structure of a first variant, in a schematic representation;

[0098] FIG. 8 a collecting structure of a second variant, in a schematic representation; and

[0099] FIG. 9 a collecting structure of a third variant, in a schematic representation.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0100] FIG. 1 shows a vane pump in a longitudinal section. The vane pump has a pump housing featuring a first end-facing wall 1, a second end-facing wall 2 and a circumferential wall 3. The end-facing walls 1 and 2 of the housing axially delineate a delivery chamber 4 on the two end-facing sides. The circumferential wall 3 extends around the delivery chamber 4 and can directly surround the delivery chamber 4, as for instance in the example embodiment. A rotor 11 of the vane pump is accommodated such that it can be rotated about a rotational axis R in the delivery chamber 4.

[0101] FIG. 2 shows the vane pump in a plan view before the end-facing wall 2 of the housing has been assembled, such that there is a clear view into the delivery chamber 4 including the rotor 11 which has already been inserted into the delivery chamber 4. The rotor 11 has guide slots 13 which guide multiple vanes 12 in a distribution around the rotational axis R such that they can be moved radially or at least substantially in the radial direction, as is usual in vane pumps. The rotor 11 and the vanes 12 together form an impeller 10 of the vane pump.

[0102] The circumferential wall 3 of the housing serves directly as a stroke structure, and its inner circumference has, for this purpose, a guide surface for the vanes 12. When the rotor 11 is rotated, the vanes 12 are pressed outwards against the guide surface of the circumferential wall 3 of the housing. When the rotor 11 is rotated, the guide surface determines how far the vanes 12 protrude beyond the outer circumference of the rotor 11. The vanes 12 delineate delivery cells, which are formed in the delivery chamber 4, in the circumferential direction. The profile of the guide surface of the circumferential wall 3 of the housing is selected such that when the rotor 10 is rotated in the direction of the rotational direction arrow indicated, for example clockwise, the delivery cells periodically increase in size on a low-pressure side of the delivery chamber 4 and decrease in size again on a high-pressure side of the delivery chamber 4 in order to expel a fluid, which flows into the delivery chamber 4 through an inlet 5 on the low-pressure side of the delivery chamber 4, at an increased pressure as a pressurised fluid on the high-pressure side of the delivery chamber 4 through an outlet 6 on the high-pressure side. In advantageous embodiments, the pump is designed to suction the fluid through the inlet 5, for example against gravity.

[0103] The pump is a multi-flow pump (in the embodiment, a dual-flow pump comprising a first flow and a second flow). The flows each have a low-pressure side and a high-pressure side. Accordingly, the delivery chamber 4 has the inlet 5 as a first inlet and the outlet 6 as a first outlet for the first flow and additionally a second inlet 7 and a second outlet 8 for the second flow. When the impeller 10 is rotated in the direction of the rotational direction arrow, the delivery cells pass through the flows consecutively in each revolution. The guide surface of the circumferential wall 3 of the housing is shaped such that the delivery cells increase in size on the low-pressure side of the first flow and decrease in size again on the high-pressure side of the first flow in each revolution, in order to expel fluid, which flows through the inlet 5 into the delivery chamber 4, at an increased pressure as a pressurised fluid on the high-pressure side of the first flow through the outlet 6 on the high-pressure side, and then increase in size again on the low-pressure side of the second flow and decrease in size again on the high-pressure side of the second flow in order to expel fluid, which flows through the inlet 7 into the delivery chamber 4, at an increased pressure as a pressurised fluid on the high-pressure side of the second flow through the outlet 8 on the high-pressure side. The vane pump can be a multi-circuit pump, as is preferred, such that the flows are fluidically separated from each other, wherein the flows can be designed for different pressures and/or delivery volumes.

[0104] The inlets 5 and 7 extend along the circumference of the circumferential wall 3 of the housing and on the end-facing sides of the end-facing walls 1 and 2 of the housing which axially face each other. The inlets 5 and 7 are offset in the circumferential direction with respect to the outlets 6 and 8 contained in the section in FIG. 1 and are indicated only schematically in FIG. 1 by dashed arrows. The outlets 6 and 8 extend through the first end-facing wall 1 of the housing and emerge on the outer end-facing side of the first end-facing wall 1 of the housing which faces axially away from the delivery chamber 4 and serves as the high-pressure connecting side of the vane pump. In order to seal the outlets 6 and 8 off from each other, the vane pump comprises an axial gasket 24 (FIG. 1) which is arranged on the outer end-facing side of the first end-facing wall 1 of the housing.

[0105] The radially inner ends of the vane slots 13 each form a sub-vane region 14 to which fluid from the high-pressure side of the respective flow is applied when the impeller 10 is rotated. For supplying the sub-vane regions 14, a supply pocket 5a and, following it in the rotational direction, a supply pocket 6a are formed in the rotational angular region of the first flow, and a supply pocket 7a and, following it in the rotational direction, a supply pocket 8a are formed in the rotational angular region of the second flow. The supply pockets 5a to 8a are formed separately from each other, each in the shape of a pocket on the end-facing side of the end-facing wall 1. The supply pocket 5a is connected to the outlet 6 of the first flow via a channel, and the supply pocket 7a is connected to the outlet 8 of the second flow via another channel. When the impeller 10 is rotated, the sub-vane regions 14 consecutively overlap with the supply pockets 5a, 6a, 7a and 8a. As they pass over the supply pockets 5a and 7a, the latter are exposed to the pressure of the high-pressure side of the respective flow. The supply pockets 6a and 8a are blind pockets which are subjected to pressure from the sub-vane regions 14 as the latter pass over them, thus ensuring a certain drop in pressure in the sub-vane regions 14 before the vanes 12 enter the rotational angular region of the next flow in each case.

[0106] In their pre-assembled state, the components of the vane pump are loosely joined to each other, such that the pre-assembled vane pump can be assembled, i.e. positioned and fastened, as an assembly unit at a desired installation location. The circumferential wall 3 and the end-facing walls 1 and 2 are held together in an axial layered assemblage. The end-facing walls 1 and 2 of the housing each rest against the circumferential wall of the housing 3 in an axial contact. The vane pump can for example be inserted with the first end-facing wall 1 of the housing first into the well of an accommodating structure and fastened to the accommodating structure in the region of the second end-facing wall 2 of the housing. In order to firmly press the housing walls 1, 2 and 3, which are only loosely joined in their pre-assembled state, against each other axially, the vane pump can comprise a spring device 25, for example a disc spring, which when assembled is axially clamped between the pump housing and an abutment on the accommodating structure, for example a base of an accommodating well, and presses the housing walls 1, 2 and 3 axially against each other with a spring force, such that the delivery chamber 4 is closed in a fluid-tight seal, aside from the inlets and outlets 5 to 8, under nominal operating conditions.

[0107] The rotor 11 is non-rotationally connected to a drive shaft 15. The drive shaft 15 passes through the second end-facing wall 2 of the housing and the rotor 11 and protrudes into the first end-facing wall 1 of the housing. The drive shaft 15 can in principle also protrude through the first end-facing wall 1 of the housing, but it is more advantageous for the first end-facing wall 1 of the housing to be provided with a blind bore, as in the example embodiment, and for the drive shaft 15 to protrude into this blind bore. A drive portion of the drive shaft 15 protrudes beyond the second end-facing wall 2 of the housing and can be rotary-driven in said drive portion. A drive wheel, for example a belt disc for a belt drive, a sprocket for a chain drive or a toothed wheel for a toothed wheel drive, can be non-rotationally connected to the drive shaft 15 in the drive portion. The passage of the shaft through the end-facing wall 2 of the housing is sealed off by means of a shaft gasket.

[0108] The drive shaft 15 is supported radially on one side of the rotor 11 in a rotary bearing on the first end-facing wall 1 of the housing and on the other side of the rotor 11 in a rotary bearing on the second end-facing wall 2 of the housing. The rotary bearings can for example be rotary slide bearings. In order to form the rotary bearing on the first end-facing wall 1 of the housing, a bearing socket 16 can be introduced into the blind bore of the first end-facing wall 1 of the housing, with which the drive shaft 15 is in rotary sliding contact. It would in principle be sufficient for the drive shaft 15 to be supported on one side; the drive shaft 15 is however more advantageously supported on both end-facing side of the rotor 11.

[0109] The rotor 11 is non-rotationally seated on the drive shaft 15 and can also be connected axially fixed to the drive shaft 15. The rotor 11 can then, as in the example embodiment, rest against an abutment 17, for example an abutment collar directly on the drive shaft 15, in an axial direction and against another abutment 18 in the opposite axial direction and thus be prevented from moving axially relative to the drive shaft 15. The other abutment 18 can, as in the example embodiment, be formed by a securing ring arranged on the drive shaft 15.

[0110] The drive shaft 15 is axially mounted in a suspended manner. The rotating unit consisting of the rotor 11 and the drive shaft 15 is axially mounted relative to the pump housing via the rotor 11. A first end-facing side of the rotor 11 forms a first axial gap with the first end-facing wall 1 of the housing, and the other, second end-facing side of the rotor 11 forms a second axial gap with the second end-facing wall 2 of the housing. The end-facing walls 1 and 2 of the housing form an axial rotary slide bearing with the rotor 11 via the respective axial gap, wherein the axial rotary slide bearing is lubricated by means of the fluid delivered by the vane pump. At least regions of the axial gaps are axially narrow enough that only leakage fluid, driven by pressure differences, is pressed or sucked through the respective axial gap.

[0111] In order to improve lubrication and (as in the example embodiment) also to improve how the rotor 11 is axially mounted, a collecting structure 20 which extends around the rotational axis R is formed in the first axial gap. The collecting structure 20 comprises an annular recess which continuously encircles the rotational axis R on the end-facing surface of the first end-facing wall 1 of the housing which faces the rotor 11, i.e. it extends 360 around the rotational axis R and is self-contained. The collecting structure 20 can in particular be formed by one annular recess in the form of an annular groove. The recess can in particular have circumferentially the same profile. In principle, however, the recess can also have a profile which changes in the circumferential direction. The collecting structure 20 can alternatively be formed on the first end-facing side of the rotor, or another collecting structure can additionally be formed on the first end-facing side of the rotor, but it is preferable for a collecting structure to be formed only on the end-facing side of the first end-facing wall 1 of the housing which axially faces the rotor 11.

[0112] In the first axial gap, an outer sealing gap which continuously encircles the collecting structure 20 circumferentially without interruption fluidically separates the collecting structure 20 from the supply pockets 5a, 6a, 7a and 8a and thus from the sub-vane regions 14 of the rotor 11. The outer sealing gap is axially delineated by an outer sealing surface 1a on the end-facing side of the first end-facing wall 1 of the housing and by a sealing surface 11a on the end-facing side of the rotor 11. The outer sealing gap 1a, 11a is configured such that fluid delivered by the vane pump can enter or exit the collecting structure 20 via the outer sealing gap 1a, 11a in the form of leakage only. The sealing surfaces 1a and 11a, which face axially opposite each other across the outer sealing gap 1a, 11a, in particular do not have a channel connecting the collecting structure 20 to one of the supply pockets 5a to 8a or to another region of the high-pressure side or low-pressure side of the delivery chamber or the vane pump as a whole. Fluid can only flow in the sealing gap 1a, 11a in accordance with the axial gap width and the surface quality of the sealing surfaces 1a and 11a.

[0113] The first axial gap also comprises an inner sealing gap which fluidically isolates the collecting structure 20 radially inwards, towards the rotational axis R (towards the drive shaft 15 in the example embodiment). The inner sealing gap is axially delineated by an inner sealing surface 1b on the end-facing side of the first end-facing wall 1 of the housing and by an inner region of the sealing surface 11a on the end-facing side of the rotor 11. The inner sealing gap 1b, 11a is advantageously configured such that only leakage can occur via this sealing gap 1b, 11a. In particular, neither the inner sealing surface 1b of the first end-facing wall 1 of the housing nor the sealing surface 11a of the rotor 11 has a channel through which fluid collected in the collecting structure 20 could flow radially inwards from it. Fluid can only flow in the inner sealing gap 1b, 11a in accordance with the axial gap width and the surface quality of the sealing surfaces 1b and 11a.

[0114] In the embodiment as an annular groove which has been selected by way of example, the collecting structure 20 is a blind groove.

[0115] The rotor 11 can form its sealing surface 11a simply by being flat. The first end-facing wall 1 of the housing can simply be flat on its end-facing side which faces the rotor 11, aside from the inlets and outlets 5 to 8 and the supply pockets 5a to 8a, or at least in the region of its sealing surfaces 1a and 1b.

[0116] The fluid which accumulates in the collecting structure 20 when the vane pump is in operation serves as a lubricant reservoir and thus improves lubrication in the first axial gap. Because the collecting structure 20 is fluidically isolated, the fluid in the collecting structure 20 also forms a sort of hydrostatic bearing for the rotor 11. Fluidically isolating the collecting structure 20 also reduces the fluid losses via the first axial gap and improves the volumetric effectiveness of the vane pump.

[0117] In the second axial gap, a collecting structure corresponding to the collecting structure 20 can likewise be provided. This other collecting structure can extend around the rotational axis R, in a comparable way to the collecting structure 20, between the drive shaft 15 and the supply pockets for the sub-vane regions 14 which are optionally also provided on the second end-facing wall 2 of the housing. Of the optionally provided supply pockets of the second end-facing wall 2 of the housing, the supply pockets 6a and 8a can be seen in the longitudinal section of FIG. 1. Tests have however shown that such an additional collecting structure 20 is not necessary.

[0118] FIGS. 3 and 4 show the first end-facing wall 1 of the housing, which in FIG. 3 is shown in a plan view onto the end-facing side which faces the rotor 11 and in FIG. 4 is shown in the longitudinal section C-C of FIG. 3. In the plan view, the rotor 11 is projected onto the end-facing wall 1 of the housing in accordance with its installation location and is indicated together with its guide slots 13 and sub-vane regions 14 in dashed lines. The projection of the rotor 11 indicates in particular the end-facing surface region of the end-facing wall 1 of the housing which the rotor 11 passes over when it is rotated. The collecting structure 20 which is embodied as a blind groove, the outer sealing surface 1a which directly adjoins the collecting structure 20 on the radially outer side and the inner sealing surface 1b of the first end-facing wall 1 of the housing which likewise directly adjoins the collecting structure 20 on the radially inner side are clearly shown. As already explained, the outer sealing surface 1a extends continuously around the collecting structure 20 circumferentially without interruption, between the collecting structure 20 and the supply pockets 5a, 6a, 7a and 8a for the sub-vane regions 14 which are located further outwards in the radial direction. The inlets 5 and 7 and the outlets 6 and 8 are formed even further outwards in the radial direction.

[0119] FIG. 5 shows a portion of the first axial gap in the plane of the longitudinal section of FIG. 1. In the portion shown, the supply pocket 8a located on the high-pressure side of the second flow opens into the first axial gap. A leakage path L of the fluid delivered by the vane pump is also indicated. In the first axial gap, the leakage path L leads from one of the delivery cells 4 which is just passing through the high-pressure side of the second flow radially inwards towards the supply pocket 8a, from the supply pocket 8a radially inwards towards the collecting structure 20 through the outer sealing gap 1a, 11a, and from the collecting structure 20 radially inwards towards the drive shaft 15. In the region of the drive shaft 15, the leakage fluid flows through the rotary slide bearing between the drive shaft 15 and the bearing socket 16 in accordance with the pressure gradient, ensuring hydrodynamic lubrication of the rotary slide bearing 15, 16, and flows off from the rotary slide bearing 15, 16 via the drive shaft 15 which is embodied as a hollow shaft. Within this context, it is also favourable for the shaft receptacle forming the first end-facing wall 1 of the housing for the drive shaft 15 to be a blind bore. This facilitates sealing off the outlets 6 and 8 on the high-pressure side of the vane pump, which is simultaneously also an outer connecting side.

[0120] FIG. 6 shows the first end-facing wall 1 of the housing, again in the same plan view as in FIG. 3, but without the rotor 11. Leakage paths L through the outer sealing gap or over the outer sealing surface 1a and through the inner sealing gap or over the inner sealing surface 1b are indicated schematically by directional arrows.

[0121] Each of FIGS. 7, 8 and 9 shows the first axial gap between the end-facing wall 1 of the housing and the rotor 11 in the immediate vicinity of the collecting structure 20. The collecting structure 20 is formed as a continuously circumferential blind groove without interruption, in accordance with the example embodiment, wherein the three collecting structures 20 shown differ from each other in their profile. Aside from the difference in profile, the collecting structure 20 and the first axial gap are otherwise the same in all three variants.

[0122] In the first variant shown in FIG. 7, the collecting structure 20 has a round profile comprising a central recess region 21 which is for example shaped as a conical section, for example semicircular, and tapers at the radially outer and/or radially inner edge into the outer sealing surface 1a and the inner sealing surface 1b via a rounded transition region 22 and 23, respectively.

[0123] In the second variant shown in FIG. 8, the collecting structure 20 has the same central recessed region 21 as in the first variant. The second variant differs from the first variant only in that the transition regions 22 and 23 are simply edged or chamfered only obliquely.

[0124] In a third variant which is shown in FIG. 9, the collecting structure 20 has a V-shaped profile which in each of the transition regions 22 and 23 simply tapers obliquely into the sealing surfaces 1a and 1b of the end-facing wall 1 of the housing. A round and in particular V-shaped profile enables the ratio of the opening area to the volume or the ratio of the radial width B.sub.20 to the cross-sectional area of the profile of the respective collecting structure 20 to be advantageously increased as comparison to for example a U-shaped profile. The opening area is understood to be the area of the collecting structure 20 level with the sealing surfaces 1a and 1b, i.e. the area between the sealing surfaces 1a and 1b. If the sealing surfaces 1a and 1b are to be axially offset with respect to each other, the opening area is understood to be the axial parallel projection of the area between the sealing surfaces 1a and 1b.

[0125] The axial gap width W.sub.1a of the outer sealing gap 1a, 11a, the axial gap width W.sub.1b of the inner sealing gap 1b, 11a, the axial depth T of the respective collecting structure 20, the radial width B.sub.1a of the outer sealing gap 1a, 11a, the radial width B.sub.1b of the inner sealing gap 1b, 11a and the radial width B.sub.20 of the respective collecting structure 20 (in this case, by way of example, the respective blind groove) are indicated in FIGS. 7 to 9. These variables advantageously meet one or more of the following relationships:

[00009]$T5W_{1a}\mathrm{or}T10W_{1a}\mathrm{or}T20W_{1a}$$T5W_{1b}\mathrm{or}T10W_{1b}\mathrm{or}T20W_{1b}$$T>0.2\mathrm{mm}\mathrm{or}T0.3\mathrm{mm}\mathrm{or}T0.4\mathrm{mm}$$T<1\mathrm{mm}\mathrm{or}T0.8\mathrm{mm}$$W_{1a}0.01\mathrm{mm}$$W_{1a}0.05\mathrm{mm}\mathrm{or}{W}_{1a}0.04\mathrm{mm}\mathrm{or}{W}_{1a}0.03\mathrm{mm}$$W_{1b}0.01\mathrm{mm}$$W_{1b}0.05\mathrm{mm}\mathrm{or}{W}_{1b}0.04\mathrm{mm}\mathrm{or}{W}_{1b}0.03\mathrm{mm}$$0.5B_{20}/T2$$B_{1a}T\mathrm{or}{B}_{1a}2T\mathrm{or}{B}_{1a}3T$$B_{1b}T\mathrm{or}{B}_{1b}2T\mathrm{or}{B}_{1b}3T$$B_{1a}{B}_{20}\mathrm{or}{B}_{1a}2B_{20}\mathrm{or}{B}_{1a}3B_{20}$$B_{1b}{B}_{20}\mathrm{or}{B}_{1b}2B_{20}\mathrm{or}{B}_{1b}3B_{20}$$B_{20}5W_{1a}\mathrm{or}{B}_{20}10W_{1a}\mathrm{or}{B}_{20}20W_{1a}$$B_{20}5W_{1b}\mathrm{or}{B}_{20}10W_{1b}\mathrm{or}{B}_{20}20W_{1b}$$B_{1a}1\mathrm{mm}\mathrm{or}{B}_{1a}1.5\mathrm{mm}\mathrm{or}{B}_{1a}2\mathrm{mm}$$B_{1b}1\mathrm{mm}\mathrm{or}{B}_{1b}1.5\mathrm{mm}\mathrm{or}{B}_{1b}2\mathrm{mm}.$

[0126] The outer sealing surface 1a and/or the inner sealing surface 1b of the first end-facing wall 1 of the housing can in particular be obtained by lapping. With regard to the surface quality, the outer sealing surface 1a and/or the inner sealing surface 1b can for example have an average surface roughness of Rz3 and/or a relative material ratio Rmr(1.0)>75% (c0 5%). It is advantageous for the reduced peak height Rpk of the outer sealing surface 1a and/or inner sealing surface 1b to be less than 0.4 m and/or for the core surface roughness Rk of the outer sealing surface 1a and/or inner sealing surface 1b to be less than 1.5 m. The sealing surface 11a of the rotor 11 should have an average surface roughness of Rz7 or less.

REFERENCE SIGNS

[0127] 1 end-facing wall of the housing [0128] 1a sealing surface, sealing stay of the end-facing wall [0129] 1b sealing surface, sealing stay of the end-facing wall [0130] 2 end-facing wall of the housing [0131] 3 circumferential wall of the housing [0132] 4 delivery chamber [0133] 5 inlet [0134] 5a supply pocket [0135] 6 outlet 45 [0136] 6a supply pocket [0137] 7 inlet [0138] 7a supply pocket [0139] 8 outlet [0140] 8a supply pocket [0141] 9 [0142] 10 impeller [0143] 11 rotor [0144] 11a sealing surface, sealing stay of the rotor [0145] 12 vane [0146] 13 guide slot [0147] 14 sub-vane region [0148] 15 drive shaft [0149] 16 bearing socket [0150] 17 abutment [0151] 18 abutment [0152] 19 [0153] 20 collecting structure [0154] 21 central recess region [0155] 22 transition [0156] 23 transition [0157] 24 axial gasket [0158] 25 spring device [0159] B.sub.1a radial width [0160] B.sub.1b radial width [0161] B.sub.20 radial width [0162] L leakage path [0163] R rotational axis [0164] T depth [0165] W axial width