ROTARY PUMP COMPRISING A LUBRICATING GROOVE IN THE SEALING STAY

Abstract

A rotary pump with a rotational direction which can be switched, including: a housing which has a pump space featuring an inlet into a low-pressure region of the pump space for a medium to be pumped and an outlet out of a high-pressure region of the pump space for the medium to be pumped; at least one rotor; at least one bearing for the at least one rotor; at least one sealing stay which axially faces the rotor and separates the low-pressure region from the high-pressure region in the rotational direction of the rotor; and a lubricant feed which feeds a lubricant from the pump space to at least the bearing, wherein the lubricant feed is formed in the sealing stay.

Claims

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

2. The rotary pump according to claim 1, wherein the medium to be pumped is fed by the lubricant feed to at least the bearing from at least one self-contained working chamber which is delineated in the rotational direction by the at least one rotor.

3. The rotary pump according to claim 1, wherein the lubricant feed is formed in the sealing stay in a region of maximum toothed engagement of the rotor.

4. The rotary pump according to claim 1, wherein the inlet and the outlet are embodied symmetrically with respect to each other.

5. The rotary pump according to claim 1, wherein the lubricant feed is arranged centrically in the sealing stay.

6. The rotary pump according to claim 1, wherein the lubricant feed is arranged eccentrically in the sealing stay.

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

8. The rotary pump according to claim 1, wherein the lubricant feed is a groove or channel in the sealing stay or comprises at least one groove and/or channel.

9. The rotary pump according to claim 1, wherein the lubricant feed comprises at least one pocket in the sealing stay and the pocket is connected to the bearing directly or via a groove or channel.

10. The rotary pump according to claim 1, wherein the lubricant feed is not short-circuited with the inlet into the pump space or the outlet out of the pump space in any position of the rotor.

11. The rotary pump according to claim 1, wherein an imaginary extension of the groove or channel intersects a rotary axis or an axis in parallel with the rotary axis of the pump.

12. The rotary pump according to claim 8, wherein an imaginary extension of the groove or channel is arranged on a straight eccentric line which connects to each other a centre point of the pump space and the rotary axis of the at least one rotor or the rotary axes of at least two rotors, which are arranged eccentrically with respect to each other.

13. The rotary pump according to claim 1, wherein the sealing stay is formed between the inlet and the outlet in the rotational direction of the rotor, and the lubricant feed extends from the bearing to at least between the inlet and the outlet.

14. The rotary pump according to claim 1, where the pump is a toothed wheel pump, wherein the lubricant feed extends from the bearing up to at least a root circle diameter of one of the toothed wheels.

15. The rotary pump according to claim 1, wherein the pump space comprises an axial cover and an axial base, and the inlet, the outlet, the sealing stay and the lubricant feed are formed in the axial cover and/or axial base of the pump space.

16. The rotary pump according to claim 1, further comprising an electric motor for driving the rotary pump.

17. The rotary pump according to claim 1, wherein the pump is an auxiliary and/or additional pump for assisting and/or at least partially replacing a main pump in a lubricant and/or coolant system of a motor vehicle.

18. The rotary pump according to any one of claim 1, wherein the lubricant feed is arranged eccentrically in the sealing stay nearer the outlet for the medium to be pumped which is envisaged for a predetermined rotational direction.

19. The rotary pump according to claim 1, wherein the rotary pump is either i) an internal-axle pump selected from the group consisting of a rotary piston pump, a reciprocating piston pump, a vane cell pump, an internally toothed wheel pump, or ii) an external-axle pump.

20. The rotary pump according to claim 1, wherein the pump is a toothed wheel pump, wherein the lubricant feed extends from the bearing up to at least a root circle diameter which is radially furthermost from the bearing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the following, the invention is described in more detail on the basis of figures. The figures show example embodiments of a rotary pump, without this restricting the invention to the embodiments shown in the figures. Features essential to the invention which can only be gathered from the figures can advantageously develop the rotary pump of the invention, individually or in combination. Specifically:

[0027] FIG. 1 shows a rotor set of a rotary pump, comprising one rotor embodied as an internally toothed wheel and one rotor embodied as an externally toothed wheel;

[0028] FIG. 2 schematically shows an inlet, an outlet and a sealing stay comprising a centrically arranged lubricant feed of the rotary pump from FIG. 1;

[0029] FIG. 3 shows an open pump housing in a view onto an axial inner side of a pump, plus a detailed view;

[0030] FIG. 4 shows a drawing of the pump inlet, pump outlet and sealing stay comprising an eccentrically arranged lubricant feed of the rotary pump from FIG. 3;

[0031] FIG. 5 shows the drawing from FIG. 4, together with the pump space and rotor;

[0032] FIG. 6 shows a drawing of the pump inlet, pump outlet and sealing stay comprising a centrically arranged lubricant feed; and

[0033] FIG. 7 shows the drawing of FIG. 6, together with the pump space and rotor.

DETAILED DESCRIPTION OF THE INVENTION

[0034] FIG. 1 shows a rotary pump 1 of a motor vehicle. The rotary pump 1 is embodied as an internally toothed wheel pump, internally toothed ring pump or gerotor pump. The delivery direction or rotational direction D of the rotary pump 1 can be switched during operation. The rotary pump 1 comprises a rotor set comprising one rotor 10 embodied as an externally toothed wheel and one rotor 11 embodied as an internally toothed wheel, which are arranged eccentrically with respect to each other. The rotor 10 can serve as a stator within which the rotor 11 is arranged eccentrically. The rotor 10 can however also be rotated, for example rotated along with and by the rotor 11. The designations “rotor 10” and “rotor 11” are therefore maintained for the purposes of the description. The two rotors 10 and 11 together embody a pump space 7 which is filled with a medium to be pumped and in which the medium is compacted on its way from the inlet to the outlet. The rotors 10, 11 delineate and/or form multiple working chambers, as viewed in the rotational direction D, in which the medium to be pumped is transported. The rotors 10, 11 divide the pump space 7 into multiple working chambers which change their volume when the rotors 10, 11 rotate.

[0035] In order to be driven, the rotary pump 1 comprises an electric motor (not shown) which is attached in drive terms to the rotor 11. The electric motor is provided in order to drive the rotor 11 in both rotational directions D. The rotary pump is embodied as an auxiliary and/or additional pump for assisting and/or at least partially replacing a main or primary pump of the motor vehicle. The rotary pump 1 is arranged in a lubricant and/or coolant system of the motor vehicle.

[0036] The rotary pump 1 also comprises a housing 2 (not shown in FIG. 1) which can form a base of the pump space 7, comprising an inlet/outlet 4, an outlet/inlet 3, a bearing 5 for the rotor 11 and two sealing stays 8 and 9 (cf. also FIG. 2) formed between the inlet/outlet 4 and the outlet/inlet 3. When the rotational direction is reversed, the inlets/outlets 3, 4 change their function. If a rotational direction D is in the clockwise direction, the inlet/outlet 4 is embodied as an inlet and the outlet/inlet 3 is embodied as an outlet. If a rotational direction D is in the anti-clockwise direction, the inlet/outlet 4 is embodied as an outlet and the outlet/inlet 3 is embodied as an inlet. For the sake of simplicity, the inlet/outlet 4 is referred to as the inlet 4 and the outlet/inlet 3 is referred to as the outlet 3 in the following. The inlet 4 and the outlet 3 are embodied symmetrically with respect to each other.

[0037] In order to lubricate the bearing 5 independently of the rotational direction, a lubricating groove which is incorporated in the sealing stay 9 forms a lubricant feed 6 using which compression oil is channeled as a lubricant from the pump space 7 to the bearing 5 of the rotor 11. The lubricant feed 6 feeds compression oil from one of the working chambers to the bearing 5 of the rotor 11. The lubricant feed 6, i.e. the lubricating groove, is formed in the region of maximum toothed engagement of the rotors 10, 11, i.e. in the region in which a tooth of the rotor 11 engages substantially completely with a region between two teeth of the rotor 10. The lubricant feed 6 is supplied with a residual medium which has not been displaced through the outlet 3 and which is charged with a compression pressure when the rotor 11 rotates further. Since the compressed medium negatively affects the performance of the rotary pump 1 and can hasten wear on the rotary pump 1, an attempt is made to avoid such compression pressures occurring, by displacing the residual medium back into the pump space 7 or the inlet 4, for example via bores in the rotor 10, 11, in pumps of the prior art. In the example embodiment of the invention, the compressed medium is advantageously discharged in this way via the lubricant feed 6, and the medium is used for lubricating the bearing 5 of the rotor 11.

[0038] In the example embodiment shown, the lubricant feed 6 is arranged centrically in the sealing stay 9, i.e. a distance between the lubricant feed 6 and the outlet 3, which connects a high-pressure side of the rotary pump 1 to for example conduits, and a distance from the inlet 4 which is assigned to the low-pressure side of the rotary pump 1 are identical or substantially identical. The lubricant feed 6 does not have a fluidic connection either to the outlet 3 or to the inlet 4. The centric arrangement of the lubricant feed 6 within the sealing stay 9 has the advantage that the lubricant feed 6 is reliably supplied with lubricant from the pump space 7 irrespective of a rotational direction of the rotary pump 1, i.e. a rotational direction of the rotors 10, 11. It can be advantageous if the sealing stay 9 is wider than in pumps of the prior art, i.e. a distance between the edges of the inlet 4 and outlet 3 which face each other and define a minimum width of the sealing stay 9 is selected to be larger than in comparable pumps which do not have the lubricant feed 6.

[0039] The lubricant feed 6 is open at its ends assigned to the bearing 5 and ports onto an outer surface of the bearing 5, whence it extends radially outwards into the sealing stay 9 and terminates in a region of the sealing stay 9 which lies between the inlet 4 and the outlet 3. The lubricant feed 6 is formed as a recess in the base of the pump space 7. The sealing stay 9, together with the rotors 10, 11, separates the low-pressure region of the pump space 7 from the high-pressure region of the pump space 7 and prevents a medium to be pumped from being able to flow directly from the inlet 4 into the outlet 3. The other sealing stay 8 also has the same function, i.e. that of preventing a direct fluidic connection between the inlet 4 and the outlet 3, although unlike the sealing stay 9, a toothed engagement between the internally toothed wheel 11 and the externally toothed wheel 10 is lacking or is at a minimum in the region of the sealing stay 8.

[0040] The medium to be pumped can for example be an oil, heavy oil, diesel or other medium which has sufficient lubricating properties to reliably lubricate the bearing 5 of the rotor 10. In this example embodiment, it is a lubricating oil for lubricating and/or cooling motor vehicle components.

[0041] The lubricant feed 6 or, respectively, an extension of an axial longitudinal axis L of the lubricant feed 6 which is indicated in FIG. 2 intersects the rotary axis R of the rotor 11. The rotor 11 can be rotary-driven and can be rotated relative to the housing 2 only and, optionally, linearly adjusted along the rotary axis R, i.e. the rotary axis R of the rotary pump 1 of the example embodiment does not change its position relative to the housing 2.

[0042] The rotary pump 1 likewise comprises a bearing in order to mount the rotor 10. As an alternative to or in addition to supplying the bearing 5 with lubricating oil, the lubricant feed 6 can in principle supply the bearing of the rotor 10 with the compression oil in order to lubricate it. The lubricating groove can for example be extended radially outwards and supply both bearings with compression oil. It is alternatively or additionally possible to incorporate an additional, in particular parallel lubricating groove which supplies the bearing of the rotor 10 with compression oil, wherein the lubricating grooves can take their compression oil from the same working chamber or from two different working chambers.

[0043] FIGS. 3, 4 and 5 show a rotary pump 1 of a second example embodiment, wherein FIG. 3 shows a view into a housing 2 of the rotary pump 1. The housing 2 comprises an inner side wall which can form a base of a pump space 7, comprising an inlet 4, an outlet 3, a bearing 5 for a rotor 11 and two sealing stays 8 and 9 formed between the inlet 4 and the outlet 3. A lubricating groove which is incorporated in the sealing stay 9 forms a lubricant feed 6 using which compression oil is channeled as a lubricant from the pump space 7 to the bearing 5 of the rotor 11.

[0044] In the second example embodiment, the inlet 4 and the outlet 3 are embodied asymmetrically, wherein the lubricant feed 6 is arranged eccentrically in the sealing stay 9, i.e. a distance between the lubricant feed 6 and the outlet 3 envisaged for a preferred rotational direction D.sub.pref, the outlet 3 connecting a high-pressure side of the rotary pump 1 to for example conduits, is smaller than a distance from the inlet 4 envisaged for the preferred rotational direction D.sub.pref, the inlet 4 being assigned to the low-pressure side of the rotary pump 1. The eccentric arrangement of the lubricant feed 6 within the sealing stay 9 is in particular advantageous if the rotary pump 1 has a preferred rotational direction D.sub.pref. In this case, arranging the lubricant feed 6 in this way increases the size of the region of the sealing stay 9 which seals the lubricant feed 6 with respect to the low-pressure side or the inlet 4, such that the lubricant is reliably prevented from being suctioned out of the lubricant feed 6 again through a fluidic connection between the lubricant feed 6 and the inlet 4. The axial longitudinal axis L of the lubricant feed 6 lies on a straight eccentric line which, in a cross-section of the rotary pump 1, connects a rotary axis of the rotor 10 and a rotary axis of the rotor 11 to each other. Although the longitudinal axis L of the lubricant feed 6 is preferably congruent with the eccentric straight line which connects the rotary axis of the rotor 10 and the rotary axis of the rotor 11, the longitudinal axis L of the lubricant feed 6 can instead however also, in modifications, extend in parallel with the eccentric straight line at a distance. In other modifications, the longitudinal axis L can in principle extend at an acute angle of preferably less than 20° to the eccentric straight line and intersect the rotary axis of the rotor 10 and/or the rotary axis of the rotor 11 or intersect it/them at a distance.

[0045] The lubricant feed 6 can also, unlike FIGS. 3, 4 and 5, be arranged in the sealing stay 9 eccentrically and nearer the inlet 4 envisaged for the preferred rotational direction D.sub.pref, in order to reliably prevent a fluidic connection between the outlet 3 envisaged for the preferred rotational direction D.sub.pref and the lubricant feed 6. This can for example be advantageous in rotary pumps 1 having a high outlet pressure, in order to reliably prevent the highly pressurised medium from being pressed into the lubricant feed 6 before the outlet 3 of the rotary pump 1 is completely closed. The region of the sealing stay 9 is additionally shown in an enlarged representation.

[0046] FIGS. 6 and 7 show a rotary pump 1 in a third example embodiment. Unlike the example embodiment in FIGS. 1 and 2, the inlet 4 and outlet 3 are embodied asymmetrically. Unlike the example embodiment in FIGS. 3, 4 and 5, the lubricant feed 6 is arranged centrically in the sealing stay 9, i.e. it has substantially identical distances from the inlet 4 and the outlet 3. The rotary pump 1 therefore comprises inlets and outlets 3, 4 which are embodied asymmetrically with respect to each other, but a lubricant feed 6 which is arranged centrically.

LIST OF REFERENCE SIGNS

[0047] 1 rotary pump [0048] 2 housing [0049] 3 outlet [0050] 4 inlet [0051] 5 bearing [0052] 6 lubricant feed [0053] 7 pump space [0054] 8 sealing stay [0055] 9 sealing stay [0056] 10 rotor [0057] 11 rotor [0058] D rotational direction [0059] D.sub.pref preferred rotational direction [0060] R rotary axis of the rotor [0061] L longitudinal centre axis of the lubricant feed