Pressure pockets on the hollow wheel

Abstract

A rotary pump includes a housing featuring a delivery space which the housing surrounds and axially delineates on the end sides; an inner rotor rotatable in the delivery space; an outer rotor rotatable about a pump rotational axis in the delivery space and forming delivery cells with the inner rotor; and a circumferential bearing wall which mounts and surrounds the outer rotor rotatably about the pump rotation axis in radial sliding contact. The circumferential bearing wall includes multiple blind pockets which are radially open towards the outer rotor and/or the outer rotor includes multiple blind pockets which are radially open towards the circumferential bearing wall.

Claims

1. A rotary pump for delivering a fluid, the rotary pump comprising: a housing featuring a delivery space which the housing surrounds and axially delineates on the end sides and which comprises an inlet for the fluid on a low-pressure side of the rotary pump and an outlet for the fluid on a high-pressure side of the rotary pump; an inner rotor rotatable in the delivery space; an outer rotor rotatable about a pump rotational axis in the delivery space and which forms delivery cells with the inner rotor; and a circumferential bearing wall which is formed by the housing or arranged in the housing and which surrounds the outer rotor and mounts it, such that it is rotatable about the pump rotational axis, in a radial sliding contact, wherein the rotary pump comprises one or both of (i) multiple blind pockets in the circumferential bearing wall which are radially open towards the outer rotor and (ii) multiple blind pockets in the outer rotor which are radially open towards the circumferential bearing wall, wherein the multiple blind pockets are fluidically separated from each other in the region of the radial sliding contact between the outer rotor and the circumferential bearing wall, wherein the rotary pump comprises one or both of (i) a chamfer on a first end side of the outer rotor along its circumferential outer periphery and (ii) an inner edge transition on the circumferential bearing wall along its circumferential inner periphery on the first end side of the outer rotor, and wherein the multiple blind pockets are arranged in an asymmetrical distribution over the circumference of the outer rotor in relation to the circumferential direction of the outer rotor.

2. The rotary pump according to the claim 1, wherein at least one of the outer rotor and the circumferential bearing wall extend(s) axially beyond at least one of the multiple blind pockets towards a first end side of the outer rotor in its/their sliding contact, such that a respective blind pocket terminates in a dead end at a first end of the blind pocket in the region of an outer circumferential surface of the outer rotor which is in sliding contact with or in the region of an inner circumferential surface of the circumferential bearing wall which is in sliding contact and is thus fluidically separated from the one or more blind pockets on the first end side of the outer rotor.

3. The rotary pump according to claim 2, wherein the outer rotor or the circumferential bearing wall extend(s) axially beyond each of the multiple blind pockets.

4. The rotary pump according to claim 1, wherein at least one of the multiple blind pockets terminates axially in an opening on the one or both of the circumferential bearing wall and the outer rotor on a second end side of the outer rotor.

5. The rotary pump according to the claim 4, wherein the one or both of the circumferential bearing wall and the outer rotor fluidically separate(s) the respective blind pocket from the one or more other blind pockets at their end which terminates in an opening, in its/their sliding contact.

6. The rotary pump according to claim 5, wherein at least one of the circumferential bearing wall and the outer rotor fluidically separate(s) each blind pocket from the one or more other blind pockets at their end which terminates in an opening, in its/their sliding contact.

7. The rotary pump according to claim 4, wherein each of the multiple blind pockets terminates axially in an opening on at least one of the circumferential bearing wall and the outer rotor on a second end side of the outer rotor.

8. The rotary pump according to claim 1, wherein the housing comprises a housing cover which axially delineates the delivery chamber on the second end side of the outer rotor, and wherein the housing cover rests against one or both of the circumferential bearing wall in an axial sealing contact and the outer rotor in an axially sealing sliding contact.

9. The rotary pump according to claim 1, wherein the housing comprises a housing cover which axially delineates the delivery chamber on the second end side of the outer rotor and forms an axial sealing gap with the circumferential bearing wall and the outer rotor, and wherein the axial sealing gap between the housing cover and the circumferential bearing wall is smaller than the axial sealing gap between the housing cover and the outer rotor.

10. The rotary pump according to claim 1, wherein the chamfer on the outer rotor overlaps with the inner edge transition on the circumferential bearing wall.

11. The rotary pump according to claim 1, wherein the second end side of the outer rotor comprises a second chamfer along its circumferential outer periphery, and the first chamfer is at least three or four times as large in the radial or axial direction as the second chamfer.

12. The rotary pump according to claim 1, wherein the first end side of the outer rotor comprises the chamfer along its circumferential outer periphery, and the chamfer measures at least 200 ?m or at least 300 ?m or at most 400 ?m or 500 ?m in the radial direction, or wherein the chamfer measures at least 200 ?m or at least 300 ?m or at most 400 ?m or at most 500 ?m in the axial direction.

13. The rotary pump according to claim 1, wherein the circumferential bearing wall does not comprise a chamfer or only comprises a small second chamfer along its circumferential inner periphery on the second end side of the outer rotor or the second end side of the outer rotor does not comprise a chamfer or only comprises a small second chamfer along its circumferential outer periphery.

14. The rotary pump according to claim 13, wherein the second end side of the outer rotor comprises a second chamfer along its circumferential outer periphery, and a first chamfer is at least three or four times as large in the radial or axial direction as the second chamfer.

15. The rotary pump according to claim 13, wherein the first end side of the outer rotor comprises a chamfer along its circumferential outer periphery, and the chamfer measures at least 200 ?m or at least 300 ?m or at most 400 ?m or 500 ?m in the radial direction, or wherein the chamfer measures at least 200 ?m or at least 300 ?m or at most 400 ?m or at most 500 ?m in the axial direction.

16. The rotary pump according to claim 1, wherein a respective blind pocket of the multiple blind pockets overlaps by more than 80% or more than 90% of its circumferential extent with either the inlet only or the outlet only.

17. The rotary pump according to claim 16, wherein the respective blind pocket overlaps by its entire circumferential extent with either the inlet only or the outlet only.

18. The rotary pump according to claim 1, wherein the rotary pump comprises four blind pockets, and the multiple blind pockets are arranged mirror-symmetrically in relation to an inner diameter of the circumferential bearing wall or an outer diameter of the outer rotor.

19. The rotary pump according to claim 1, wherein the multiple blind pockets extend at least twice as far or at least three times as far in the circumferential direction of the outer rotor as in the radial direction of the outer rotor.

20. The rotary pump according to claim 1, wherein an axial extent of at least one of the multiple blind pockets from a first end of the blind pocket up to a second end of the blind pocket corresponds to at least 70% or at least 80% of an axial extent of the outer rotor from a first end side up to a second end side.

21. The rotary pump according to claim 1, wherein the chamfer is a rotor bevel or wherein the inner edge transition is an inner edge burr.

22. A rotary pump for delivering a fluid, the rotary pump comprising: a housing featuring a delivery space which the housing surrounds and axially delineates on the end sides and which comprises an inlet for the fluid on a low-pressure side of the rotary pump and an outlet for the fluid on a high-pressure side of the rotary pump; an inner rotor rotatable in the delivery space; an outer rotor rotatable about a pump rotational axis in the delivery space and which forms delivery cells with the inner rotor; and a circumferential bearing wall which is formed by the housing or arranged in the housing and which surrounds the outer rotor and mounts it, such that it is rotatable about the pump rotational axis, in a radial sliding contact, wherein the rotary pump comprises a multiple blind pockets on the circumferential bearing wall which are radially open towards the outer rotor, wherein the multiple blind pockets are fluidically separated from each other in the region of the radial sliding contact between the outer rotor and the circumferential bearing wall; wherein each of the multiple blind pockets terminates axially in an opening on the one or both of the circumferential bearing wall and the outer rotor on a second end side of the outer rotor, and wherein the rotary pump comprises four blind pockets, wherein two of the blind pockets overlap by more than 80% or more than 90% of their circumferential extent with the inlet only, and the other two blind pockets overlap by more than 80% or more than 90% of their circumferential extent with the outlet only.

23. A rotary pump for delivering a fluid, the rotary pump comprising: a housing featuring a delivery space which the housing surrounds and axially delineates on the end sides and which comprises an inlet for the fluid on a low-pressure side of the rotary pump and an outlet for the fluid on a high-pressure side of the rotary pump; an inner rotor rotatable in the delivery space; an outer rotor rotatable about a pump rotational axis in the delivery space and which forms delivery cells with the inner rotor; and a circumferential bearing wall which is formed by the housing or arranged in the housing and which surrounds the outer rotor and mounts it, such that it is rotatable about the pump rotational axis, in a radial sliding contact, wherein the rotary pump comprises one or both of (i) multiple blind pockets in the circumferential bearing wall which are radially open towards the outer rotor and (ii) multiple blind pockets in the outer rotor which are radially open towards the circumferential bearing wall, wherein the multiple blind pockets are fluidically separated from each other in the region of the radial sliding contact between the outer rotor and the circumferential bearing wall, and wherein at least one of the outer rotor and the circumferential bearing wall extend(s) axially beyond at least one of the multiple blind pockets towards a first end side of the outer rotor in its/their sliding contact, such that a respective blind pocket terminates in a dead end at a first end of the blind pocket in the region of an outer circumferential surface of the outer rotor which is in sliding contact with or in the region of an inner circumferential surface of the circumferential bearing wall which is in sliding contact and is thus fluidically separated from the one or more blind pockets on the first end side of the outer rotor, and wherein the multiple blind pockets are arranged in an asymmetrical distribution over the circumference of the outer rotor in relation to the circumferential direction of the outer rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention shall be explained below on the basis of an example embodiment. Features disclosed by the example embodiment advantageously develop the subject-matter of the claims and the embodiments explained above, but do not restrict the invention. There is shown:

(2) FIG. 1 a plan view onto the delivery space of the rotary pump;

(3) FIG. 2 a section in the axial direction of the rotary pump with a delivery member;

(4) FIG. 3 a detailed view of the section from FIG. 2;

(5) FIG. 4 an axial section through the outer rotor;

(6) FIG. 5 a detailed view of the axial section from FIG. 4;

(7) FIG. 6 a plan view onto the delivery space of the rotary pump with no delivery member;

(8) FIG. 7 an axial section through the rotary pump with no delivery member;

(9) and

(10) FIG. 8 a detailed view of the axial section from FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

(11) All the figures show a rotary pump and its components in an example embodiment. An aspect of the invention is not restricted to the example embodiment and can be embodied in accordance with the preceding embodiments.

(12) FIG. 1 shows a plan view onto the delivery space of the rotary pump, while FIG. 2 shows a section through the rotary pump according to FIG. 1 in the axial direction of the rotary pump. FIG. 3 shows a detailed view of FIG. 2. FIGS. 6 to 8 show the rotary pump of FIG. 1, but without the delivery member 3, 4.

(13) The rotary pump comprises a housing 1 featuring a delivery space 5 which the housing 1 surrounds and axially delineates on the end sides. As can be seen in particular in FIGS. 2 and 7, the housing 1 comprises a housing cup 11 and a housing cover 12. The housing cover 12 delineates the delivery space in the axial direction, while the housing cup 11 surrounds the delivery space in the radial direction and axially delineates it on the side facing away from the housing cover 12. The delivery space 5 comprises an inlet 6 for a fluid on a low-pressure side of the rotary pump and an outlet 7 for the fluid on the high-pressure side of the pump.

(14) A delivery member which is formed in the delivery space 5 delivers the fluid from the low-pressure side of the rotary pump, in particular the inlet 6, to the high-pressure side of the rotary pump, in particular the outlet 7. The rotary pump is embodied as an internal toothed wheel pump or gerotor pump. The delivery member comprises an outer rotor 3 and an inner rotor 4, wherein the outer rotor 3 is formed by an internally toothed ring, the inner rotor 4 is formed by an externally toothed wheel, and the teeth of the inner rotor 4 can be moved into engagement with the teeth of the outer rotor 3 by rotating the two rotors. The inner rotor 4 preferably comprises one tooth less than the outer rotor 3. In the example embodiment, the outer rotor 3 comprises five teeth and the inner rotor 4 comprises four teeth, wherein the number of individual teeth is only an example and can vary.

(15) Due to the engagement between the inner rotor 4 and the outer rotor 3, the two rotors form delivery cells which can change their volume in the circumferential direction of the outer rotor 3 as the two rotors rotate. In the present example embodiment, the inner rotor 4 is driven by a drive means, in particular a drive shaft, as disclosed in FIG. 2. The inner rotor 4 is mounted such that it can rotate about the pump rotational axis R4 and drives the outer rotor 3, in particular by the individual teeth engaging with each other. The inner rotor 4 is preferably driven by means of an electric motor. In alternative embodiments, the inner rotor 4 can also for example be driven by the assembly to be supplied. Also, in alternative embodiments, the outer rotor 3 can also be driven by means of a drive means, wherein the inner rotor 4 is driven via the outer rotor 3.

(16) The pump rotational axis R4 of the inner rotor 4 is formed eccentrically with respect to the pump rotational axis R3 of the outer rotor 3, i.e. the pump rotational axis R4 of the inner rotor 4 and the pump rotational axis R3 of the outer rotor 3 exhibit an offset. The eccentricity between the pump rotational axis R3 of the outer rotor 3 and the pump rotational axis R4 of the inner rotor 4 is constant in the present example embodiment, but can also be variable in alternative embodiments. If the eccentricity between the two pump rotational axes is variable, it can be changed, in particular controlled, for example in accordance with the operational state of the rotary pump.

(17) The housing cup 11 forms a circumferential bearing wall 2 which surrounds the outer rotor 3 and mounts it, such that it can rotate about the pump rotational axis R3, in a sliding contact. In alternative embodiments, the circumferential bearing wall 2 can also for example be formed by a separate ring which is inserted into the delivery space 5. As shown for example in FIG. 2, the circumferential bearing wall 2 is formed in one piece with the housing cup 11, in particular an end wall of the housing cup 11, in particular in an original-moulding method.

(18) As can be seen in FIG. 1, the circumferential bearing wall 2 comprises multiple blind pockets 21, 22, 23, 24 which are radially open towards the outer rotor 3 and fluidically separated from each other in the region of the sliding contact between the outer rotor 3 and the circumferential bearing wall 2. In accordance with the example embodiment, the rotary pump comprises four blind pockets 21, 22, 23, 24 which are formed in the circumferential bearing wall 2. In alternative embodiments, the number of blind pockets can vary and is not intended to be restricted to four. The blind pockets are fluidically separated from each other in every rotational position of the outer rotor 3, i.e. irrespective of the rotational angular position of the outer rotor 3, the blind pockets 21, 22, 23, 24 are fluidically separated from each other in the region of the radial sliding contact between the outer rotor 3 and the circumferential bearing wall 2.

(19) In alternative embodiments, the blind pockets 21, 22, 23, 24 are formed in the outer rotor 3 and are radially open towards the circumferential bearing wall 2. Even if the blind pockets 21, 22, 23, 24 are formed in the outer rotor 3, they are fluidically separated from each other in the region of the radial sliding contact between the outer rotor 3 and the circumferential bearing wall 2, irrespective of the rotational angular position of the outer rotor 3.

(20) The circumferential bearing wall 2 surrounds the outer rotor 3 in a radial sliding contact in the region of a first end side 31 of the outer rotor 3. In particular, the outer circumferential surface of the outer rotor 3 is in sliding contact with the inner circumferential surface of the circumferential bearing wall 2 over the entire outer circumference of the outer rotor 3 and/or the entire inner circumference of the circumferential bearing wall 2 in the region of the first end side 31 of the outer rotor 3, in order to form a radial sealing gap. The radial sealing gap extends in the axial direction of the outer rotor 3 over at least 10%, in particular at least 15%, of the axial extent of the outer rotor 3 from its first end side 31 up to its second end side 32.

(21) As can be seen in FIG. 1 and FIG. 6, the blind pockets 21, 22, 23, 24 are arranged in an asymmetrical distribution over the circumference of the outer rotor 3 in relation to the circumferential direction. In particular, the blind pockets 22 and 23 are at a distance from each other, over the circumference of the outer rotor 3 in relation to the circumferential direction, which is greater than the other distances between the individual blind pockets. The distance between the blind pocket 23 and the blind pocket 24 is then for example smaller than the distance between the blind pockets 22 and 23.

(22) As can be seen in particular from FIG. 6, the blind pockets 23 and 24 can overlap with the outlet 7 only, in the circumferential direction of the outer rotor 3 and/or in the circumferential direction of the circumferential bearing wall 2, by more than 90% of their circumferential extent. In particular, the blind pockets 23 and 24 completely overlap with the outlet 7 in the circumferential direction of the circumferential bearing wall 2. The blind pockets 21 and 22 can also overlap with the inlet 6 only, in the circumferential direction of the outer rotor 3 and/or in the circumferential direction of the circumferential bearing wall 2, by more than 90% of their circumferential extent. In particular, the blind pockets 21 and 22 completely overlap with the inlet 6 in the circumferential direction of the circumferential bearing wall 2.

(23) As disclosed in FIGS. 2 and 6, the rotary pump comprises four blind pockets 21, 22, 23, 24, which are arranged mirror-symmetrically in relation to the inner diameter d of the circumferential bearing wall 2 and/or the outer diameter D of the outer rotor 3, wherein the blind pockets 21 and 22 form a first pair of pockets and the blind pockets 23 and 24 form a second pair of pockets, respectively, wherein the two pairs of pockets are formed mirror-symmetrically with respect to each other in relation to the inner diameter d of the circumferential bearing wall 2 and/or the outer diameter D of the outer rotor 3. The axis of symmetry and/or inner diameter d of the circumferential bearing wall 2 and/or the outer diameter D of the outer rotor 3 are indicated in FIG. 6 as a dashed double arrow, wherein the blind pockets 21, 22 of the first pair of pockets overlap with the inlet 6 only by more than 80% or more than 90% of their circumferential extent, and the blind pockets 23, 24 of the second pair of pockets overlap with the outlet 7 only by more than 80% or more than 90% of their circumferential extent.

(24) The blind pockets 21, 22, 23, 24 preferably extend at least twice as far and preferably at least three times as far in the circumferential direction of the outer rotor 3 as in the radial direction of the outer rotor 3. As can be seen in particular from the example of the blind pocket 24 in FIGS. 3 and 8, the axial extent of the blind pockets 21, 22, 23, 24 from a first end 24a of the pocket up to a second end 24b of the pocket can correspond to at least 70%, preferably at least 80%, of the axial extent of the outer rotor 3 from a first end side 31 up to a second end side 32.

(25) In relation to the circumference of the outer rotor 3, the blind pockets 21, 22, 23, 24 together exhibit an extent in the circumferential direction of the outer rotor 3 which corresponds to at least 20%, in particular at least 25%, of the circumference of the outer rotor 3, i.e. the blind pockets 21, 22, 23, 24 preferably overlap at least 20% of the outer circumference of the outer rotor 3, in particular at least 25% of the outer circumference of the outer rotor 3.

(26) In relation to the outer diameter D of the outer rotor 3, the blind pockets 21, 22, 23, 24 exhibit a radial extent which preferably corresponds to at most 10% of the outer diameter D of the outer rotor 3, in particular at most 8% of the outer diameter D of the outer rotor 3.

(27) As can be seen in particular from the blind pocket 24 in FIGS. 3 and 8, the outer rotor 3 extends axially beyond the blind pocket 24 towards its first end side 31 in its sliding contact. Preferably, the outer rotor 3 extends axially beyond each of the blind pockets 21, 22, 23, 24 towards its first end side 31 in its sliding contact. In accordance with the example embodiment, the outer rotor 3 extends further in the axial direction than the blind pockets 21, 22, 23, 24.

(28) The circumferential bearing wall 2 also extends axially beyond the blind pocket 24 towards the first end side 31 of the outer rotor 3 in its sliding contact. Preferably, the circumferential bearing wall 2 extends axially beyond each of the blind pockets 21, 22, 23, 24 towards the first end side 31 of the outer rotor 3 in its sliding contact. As can be seen in particular in FIG. 3, the circumferential bearing wall 2 and the outer rotor 3 exhibit the same axial extent. The blind pocket 24, however, exhibits an axial extent which is smaller than the axial extent of the circumferential bearing wall 2 and outer rotor 3.

(29) Because the outer rotor 3 and the circumferential bearing wall 2 extend axially beyond the blind pockets 21, 22, 23, 24 towards a first end side 31 of the outer rotor 3 in their sliding contact, the blind pockets 21, 22, 23, 24 terminate in a dead end in the region of the outer circumferential surface of the outer rotor 3 which is in sliding contact and/or in the region of the inner circumferential surface of the circumferential bearing wall 2 which is in sliding contact. The outer rotor 3 and the circumferential bearing wall 2 also form a radial sealing gap in the region of the first end side 31 of the outer rotor 3. The radial sealing gap is not breached by any of the blind pockets 21, 22, 23, 24. In this way, the blind pockets 21, 22, 23, 24 are fluidically separated from each other in the region of the first end side 31 of the outer rotor 3.

(30) The blind pocket 24, preferably each of the blind pockets 21, 22, 23, 24, terminates axially in an opening on the circumferential bearing wall 2 in the region of the second end side 32 of the outer rotor 3, i.e. the blind pocket 24, preferably each of the blind pockets 21, 22, 23, 24, comprises a second end 24b of the pocket, which is formed with an opening, in the region of the second end side 32 of the outer rotor 3.

(31) The outer rotor 3 and the circumferential bearing wall 2 do not extend axially beyond the blind pocket 24, preferably each of the blind pockets 21, 22, 23, 24, towards the second end side 32 of the outer rotor 3 in their sliding contact. The circumferential bearing wall 2 and the outer rotor 3 fluidically separate the blind pockets 21, 22, 23, 24 from each other at their end 24b which terminates in an opening, in their sliding contact between the individual blind pockets 21, 22, 23, 24.

(32) The housing cover 12, which axially delineates the delivery chamber 5 on the second end side 32 of the outer rotor 3, rests against the circumferential bearing wall 2 in an axial sealing contact and forms an axial sealing gap with the circumferential bearing wall 2. The housing cover 12 rests against the outer rotor 3 in an axial sliding contact. In particular, the second end side 32 of the outer rotor 3 and the housing cover 12 exhibit an axial sealing gap. The housing cover 12 rests against the outer rotor 3 in an axial sliding contact, in particular an axial sealing contact, wherein the axial sealing gap between the housing cover 12 and the circumferential bearing wall 2 is smaller than the axial sealing gap between the housing cover 12 and the outer rotor 3.

(33) The axial sealing gap between the housing cover 12 and the circumferential bearing wall 2 is formed over the entire circumference of the circumferential bearing wall 2 in the circumferential direction of the outer rotor 3. In this way, the blind pockets 21, 22, 23, 24 are fluidically separated from each other in the region of the second end side 32 of the outer rotor 3 by the circumferential bearing wall 2 and the housing cover 12.

(34) The axial sealing gap between the housing cover 12 and the outer rotor 3 is formed over the entire circumference of the outer rotor 3 in the circumferential direction of the outer rotor 3. The axial sealing gap extends between the second end side 32 of the outer rotor 3 and the housing cover 12. In this way, the blind pockets 21, 22, 23, 24 are fluidically separated from each other in the region of the second end side 32 of the outer rotor 3. In particular, since the blind pockets 21, 22, 23, 24 comprise an end 24b which terminates in an opening in the region of the second end side 32 of the outer rotor 3, the blind pockets 21, 22, 23, 24 are fluidically separated from each other in the region of the second end 24b of the pocket by the axial sealing gap. In particular, the blind pockets 21, 22, 23, 24 are fluidically separated from each other by the axial sealing gap between the housing cover 12 and the circumferential bearing wall 2 and the axial sealing gap between the housing cover 12 and the outer rotor 3 in the region of the second end side 32 of the outer rotor 3.

(35) As shown in particular in FIGS. 4 and 5, the first end side 31 of the outer rotor 3 comprises a chamfer 31a along its circumferential outer periphery. As can be seen in particular from FIG. 5, the chamfer 31a is formed in accordance with the present example embodiment as a rotor bevel, wherein the rotor bevel preferably exhibits an angle of 45? and extends at least 300 ?m in the radial and axial directions. In alternative embodiments, the rotor bevel can also exhibit a different angle, for example an angle of 60?. In particular, the first end side 31 of the outer rotor 3 does not comprise a sharp-edged transition between the first end side 31 and the outer circumferential surface along its circumferential outer periphery.

(36) As disclosed in particular in FIG. 8, the circumferential bearing wall 2 comprises an inner edge transition 2a along its circumferential inner periphery on the first end side 31 of the outer rotor 3, i.e. on the axial side of the first end side 31 of the outer rotor 3. The inner edge transition 2a can be rounded, i.e. can exhibit a radius. In accordance with the example embodiment, the inner edge transition 2a is formed as an inner edge burr over the entire length of the circumferential inner periphery. The circumferential bearing wall 2 is formed in one piece with the end wall of the housing 1, in particular the housing cup 11, facing the first end side 31 of the outer rotor 3, and the inner edge transition 2a is formed along the inner edge between the end wall and the circumferential bearing wall 2.

(37) The inner edge transition is preferably an inner edge burr which measures at least 300 ?m in the radial and axial directions, wherein the inner edge burr exhibits an angle of 45? to the axial direction of the outer rotor 3.

(38) When the outer rotor 3 is installed, the inner edge burr and the rotor bevel 31a mutually overlap, i.e. the inner edge burr is formed in accordance with the dimensions and angles of the rotor bevel, and/or the rotor bevel 31a is formed in accordance with the dimensions and angles of the inner edge burr. The outer rotor 3 preferably forms a sliding contact with the circumferential bearing wall 2 in the region of the rotor bevel 31a.

(39) The second end side 32 of the outer rotor 3 does not comprise a chamfer or only comprises a small second chamfer 32a. The small second chamfer 32a extends at most 100 ?m in the radial and axial directions. The outer circumferential edge 32a of the outer rotor 3 is preferably formed as a sharp edge on its second end side 32.

(40) If the outer rotor 3 comprises a second small chamfer 32a on its outer circumferential edge of the second end side 32, said second small chamfer 32a corresponds to at most a third of the first chamfer 31a.

LIST OF REFERENCE SIGNS

(41) 1 housing 11 housing cup 12 housing cover 2 circumferential bearing wall 2a inner edge transition 21 blind pocket 22 blind pocket 23 blind pocket 24 blind pocket 24a first end of the pocket 24b second end of the pocket 3 outer rotor 31 first end side 31a first chamfer 32 second end side 32a second chamfer 4 inner rotor 5 delivery space 6 inlet 7 outlet d inner diameter D outer diameter R3 pump rotational axis R4 pump rotational axis of the inner rotor