ROTARY VANE PUMP

Abstract

A rotary vane pump includes a pump housing, a stator, a rotor, a plurality of vanes which are accommodated in the rotor so as to be displaceable in the radial direction, so that they delimit a plurality of pump chambers between themselves, the stator and the rotor. A radially inner cam surface is provided, against which the vanes rest, wherein secondary chambers are delimited in the radial direction between the cam surface and the rotor and in the circumferential direction between the vanes, with a suction inlet and a pressure outlet being assigned to the secondary chambers.

Claims

1. Rotary vane pump having a pump housing, a stator, a rotor, a plurality of vanes which are accommodated in the rotor so as to be displaceable in the radial direction, so that they delimit a plurality of pump chambers between themselves, the stator and the rotor, wherein a radially inner cam surface is provided, against which the vanes rest, wherein secondary chambers are delimited in the radial direction between the cam surface and the rotor and in the circumferential direction between the vanes, with a suction inlet and a pressure outlet being assigned to the secondary chambers.

2. Rotary vane pump according to claim 1, wherein the cam surface is located axially inside the rotor.

3. Rotary vane pump according to claim 1, wherein the cam surface has a width in the axial direction of between 5% and 15% of the axial length of the rotor.

4. Rotary vane pump according to claim 1, wherein the cam surface is formed in one piece with an end wall of the pump housing.

5. Rotary vane pump according to claim 1, wherein connection channels for pump chambers are formed radially within the cam surface.

6. Rotary vane pump according to claim 1, wherein the volume inside the rotor delimited by the slots for receiving the vanes, the end walls of the pump housing and the end faces of the vanes is connected to a suction inlet and a pressure outlet.

7. Rotary vane pump according to claim 1, wherein the vanes are designed in a stepped manner on the radially inner side, with a guide surface which cooperates with the cam surface, and a radially further inner end face which is accommodated within the rotor.

8. Rotary vane pump according to claim 7, wherein the end face protrudes beyond the guide surface by a length (h) in the order of 5% to 15% of the height of the vane.

9. Rotary vane pump according to claim 2, wherein the cam surface has a width in the axial direction of between 5% and 15% of the axial length of the rotor.

10. Rotary vane pump according to claim 2, wherein the cam surface is formed in one piece with an end wall of the pump housing.

11. Rotary vane pump according to claim 2, wherein connection channels for pump chambers are formed radially within the cam surface.

12. Rotary vane pump according to claim 2, wherein the volume inside the rotor delimited by the slots for receiving the vanes, the end walls of the pump housing and the end faces of the vanes is connected to a suction inlet and a pressure outlet.

13. Rotary vane pump according to claim 2, wherein the vanes are designed in a stepped manner on the radially inner side, with a guide surface which cooperates with the cam surface, and a radially further inner end face which is accommodated within the rotor.

14. Rotary vane pump according to claim 3, wherein the cam surface is formed in one piece with an end wall of the pump housing.

15. Rotary vane pump according to claim 3, wherein connection channels for pump chambers are formed radially within the cam surface.

16. Rotary vane pump according to claim 3, wherein the volume inside the rotor delimited by the slots for receiving the vanes, the end walls of the pump housing and the end faces of the vanes is connected to a suction inlet and a pressure outlet.

17. Rotary vane pump according to claim 3, wherein the vanes are designed in a stepped manner on the radially inner side, with a guide surface which cooperates with the cam surface, and a radially further inner end face which is accommodated within the rotor.

18. Rotary vane pump according to claim 4, wherein connection channels for pump chambers are formed radially within the cam surface.

19. Rotary vane pump according to claim 4, wherein the volume inside the rotor delimited by the slots for receiving the vanes, the end walls of the pump housing and the end faces of the vanes is connected to a suction inlet and a pressure outlet.

20. Rotary vane pump according to claim 4, wherein the vanes are designed in a stepped manner on the radially inner side, with a guide surface which cooperates with the cam surface, and a radially further inner end face which is accommodated within the rotor.

Description

[0013] The invention will be described below on the basis of an embodiment which is illustrated in the appended drawings. In the drawings:

[0014] FIG. 1 shows a perspective view of the rotary vane pump, wherein part of the housing is shown transparent so that the inner workings of the pump are visible;

[0015] FIG. 2 shows the rotary vane pump in FIG. 1, wherein a housing cover is removed;

[0016] FIG. 3 shows a first cross-section through the rotary vane pump;

[0017] FIG. 4 shows a second cross-section through the rotary vane pump;

[0018] FIG. 5 shows a perspective view of a section along the plane V-V in FIG. 4;

[0019] FIG. 6 shows a perspective view of a section along the plane VI-VI in FIG. 4;

[0020] FIG. 7 shows the section along the plane VI-VI, wherein parts of the pump housing are shown transparent to make fluid channels visible;

[0021] FIG. 8 shows a section along the plane VII-VII in FIG. 4; and

[0022] FIG. 9 shows the detail IX in FIG. 8 on an enlarged scale.

[0023] FIGS. 1 to 9 schematically show a rotary vane pump 1 that can be used in particular to provide a volume flow of hydraulic fluid in a hydraulic unit.

[0024] The rotary vane pump 1 has a pump housing 2, which is formed from a main body 3 and a housing cover 4. A rotor 5 is arranged inside the housing and is mounted on a shaft 6 for conjoint rotation. This can be driven by an electric motor, not shown.

[0025] The rotary vane pump is a two-stroke pump, so that the housing cover 4 has two intake openings 7 and two delivery openings 8.

[0026] The rotor 5 has a plurality of slots 10, each of which receives a vane 12.

[0027] The vanes interact with their radially outer end with the inner face of a stator 14, which is accommodated in the pump housing 2.

[0028] The rotary vane pump 1 has a cam surface 16 against which the vanes 12 rest with their radially inner side.

[0029] The cam surface 16 is formed here as a projection on the end face of the main body 3 facing the rotor 5, wherein the rotor 5 is designed to be axially shorter in this region. In its radially outer region, the rotor 5 is designed with its full width (see FIG. 4), so that the rotor 5 and the cam surface 16 overlap each other (in the region of the right plane of section in FIG. 4).

[0030] Specifically, the vanes 12 have a guide surface 18 (see in particular FIG. 9), which is stepped in relation to the radially inner end face 20 of the vanes 12 (see in particular FIG. 3).

[0031] The height of step h (see FIG. 3) is in the order of 5 to 15% of the total height H of the vanes 12.

[0032] The width b of the guide surface 18 (see also FIG. 3) is in the order of 10 to 15% of the total width B of the vanes 12.

[0033] The cam surface 16, together with the guide surface 18, provides a positive guide for the vanes 12, which ensures that the vanes 12 move outwards when the rotor 5 rotates, even if the centrifugal forces acting are relatively small.

[0034] As can be seen in particular in FIG. 8, the course of the cam surface 16 corresponds to an envelope contour formed from the guide surfaces 18 of the vanes 12, which is created when the rotor 5 rotates and the vanes 12 simultaneously make contact with the stator 14. It is advantageous, for example, to design the vanes 12 in this region to be of constant thickness; the radii of the outer and inner guide surfaces may indeed be different, but should have a common central axis. Deviations from this are possible, since a functionally suitable envelope contour can, nevertheless, be constructed.

[0035] As can be seen in particular in FIG. 8, the course of the cam surface 16 corresponds to the course of the inner contour of the stator 14. In other words, the distance between the cam surface 16 and the inner face of the stator 14 measured in the radial direction is constant along the circumference of the cam surface.

[0036] Due to the offset between the guide surface 18 and the further inner end face 20 of the vane, a shoulder 22 is formed which acts as a seal. The shoulder 22 prevents hydraulic fluid from entering the corresponding slot 10 in the rotor 5 from the delivery chambers between the vanes 12.

[0037] A special feature of the rotary vane pump 1 is that a total of three different types of delivery chambers are used to provide the volume flow.

[0038] The majority of the volume flow is provided by the main chambers, which are delimited in the circumferential direction between adjacent vanes 12 and in the radial direction between the rotor 5 and the stator 14. In the axial direction, the main chambers, which are marked here with the reference sign 30, are delimited between the opposing end faces of the main body 3 and the housing cover 4 of the pump housing 2.

[0039] Another type of delivery chamber is constituted by secondary chambers 32, which are delimited between the cam surface 16 and the inner face 34 of the rotor 5 opposite the cam surface 16. These secondary chambers have a radial height of almost zero in the region I in FIG. 7, while their radial height is maximal in the region II in FIG. 7.

[0040] FIG. 7 also shows a suction inlet 36 associated with the secondary chambers 32 and a pressure outlet 38. FIG. 7 shows a pump with two different displacements per pump stream. The stream with smaller displacement has a simplified intake port in the form of the two holes leading to the rotor chamber of the electric motor; this flow is used to cool the electric motor. The pressure port of the secondary chambers 32 of the smaller stream leads into the suction region of the main chambers via a groove. If the pump strokes are of the same size, it is advantageous to design the intake and pressure outlets 36 and 37 for both streams.

[0041] Lastly, there is a third type of delivery chamber, hereinafter referred to as auxiliary chambers 40. These are formed within the slots 10 in the rotor 5 between the walls of the rotor and the end faces 20 of the vanes 12. Here, the vanes 12 act similarly to the pistons of a piston pump in that, during each revolution, they are pushed into the corresponding slot 10 twice (corresponding to an ejection movement of the hydraulic fluid) and are forced axially outwards twice (corresponding to the intake phase).

[0042] The associated intake and pressure ports are denoted here by the reference sign 42.

[0043] Due to the three different types of delivery chambers, the rotary vane pump 1 has a particularly large displacement per revolution and thus a high delivery capacity with a small overall volume.