Adjustable Vane Pump

Abstract

An adjustable vane pump, in particular an oil pressure pump, with a suction side and a pressure side, with a housing and with a rotor, which is supported in the housing so as to be rotatable about a rotor axis and carries at least one vane supported movably in a radial direction, wherein the housing comprises a housing floor and a housing cover transversely to the rotor axis, and wherein an adjustment cage that is arranged between the housing floor and the housing cover, encloses the rotor and the vane and is adjustable transversely to the rotor axis is provided in the housing, wherein the housing and the adjustment cage delimit a pressure chamber fluidically connected to the pressure side, wherein a restoring element is provided, which pushes the adjustment cage into a base end position, and wherein the adjustment cage is deflected from the base end position when a limit operating variable is exceeded in the pressure chamber.

Claims

1. An adjustable vane pump, in particular oil pressure pump, with a suction side and a pressure side, with a housing and with a rotor, which is supported in the housing so as to be rotatable about a rotor axis and carries at least one vane supported movably in a radial direction, wherein the housing comprises a housing floor and a housing cover transversely to the rotor axis, and wherein an adjustment cage that is arranged between the housing floor and the housing cover, encloses the rotor and the vane and is adjustable transversely to the rotor axis is provided in the housing, characterized in that the housing and the adjustment cage delimit a pressure chamber connected fluidically to the pressure side, wherein a restoring element is provided, which pushes the adjustment cage into a base end position, and wherein the adjustment cage is deflected from the base end position if a limit operating variable is exceeded in the pressure chamber.

2. The vane pump according to claim 1, characterized in that the rotor is driven by an electric motor formed as a rotor drive, wherein the rotor drive is operated in the nominal speed range of about 3000 to 4000 revolutions/min, both when the adjustment cage is in the base end position and when the adjustment cage is deflected from the base end position.

3. The vane pump according to claim 2, characterized in that the rotor drive is operated at a nominal speed of about 3500 rev/min so that the rotor drive has the maximum efficiency.

4. The vane pump according to claim 1, characterized in that the adjustment cage is deflected into a deflection end position on exceeding of the limit operating variable either abruptly or continuously as the limit operating variable increases.

5. The vane pump according to claim 4, characterized in that at least one of the speed and the torque of the rotor drive are identical or substantially identical in the base end position and the deflection end position.

6. The vane pump according to claim 4, characterized in that the conveying volume in the base end position is 1.5 to 4 ccm/rev, and in that the conveying volume in the deflection end position is 0.2 to 1.4 ccm/rev, and in that the conveying volume in the base end position is 5 to 201/min, and in that the conveying volume in the deflection end position is 0.5 to 41/min.

7. The vane pump according to claim 4, characterized in that in the deflection end position a pressure of between 30 and 60 bar, can be applied to a pressure consumer.

8. The vane pump according to claim 1, characterized in that the restoring element extends perpendicularly to the rotor axis and/or in that the restoring element is supported on the housing on the one hand and on the adjustment cage on the other.

9. The vane pump according to claim 1, characterized in that the housing and the adjustment cage delimit the pressure chamber and an opposing restoring element chamber in a sealing manner.

10. The vane pump according to claim 1, characterized in that the housing has a pressure outlet connected to the pressure side, wherein the pressure outlet is fluidically connected to the pressure chamber by a fluid line.

11. The vane pump according to claim 1, characterized in that the adjustment cage rests, in the base end position, on a first stop on the housing side and in that the adjustment cage rests, in the deflection end position, on a second stop on the housing side opposite the first stop.

12. The vane pump according to claim 1, characterized in that the adjustment cage is formed as a cuboid and/or in that the housing is formed in two parts with a box-shaped base part and a plate-shaped housing cover.

13. The vane pump according to claim 1, characterized in that the limit operating variable is formed as a limit pressure.

14. The vane pump according to claim 13, characterized in that the limit pressure is between 1 and 7 bar, and in that the deflection end position is reached at a pressure of from 0.5 to 10 bar above the limit pressure.

15. The vane pump according to claim 1, characterized in that the limit operating variable is formed as a limit temperature, wherein a temperature-sensitive element is provided so that the adjustment cage is deflected counter to the restoring force (FR) of the restoring element when the limit temperature is exceeded.

16. A system comprising: a vane pump with a suction side and a pressure side, with a housing and with a rotor, which is supported in the housing so as to be rotatable about a rotor axis and carries at least one vane supported movably in a radial direction, wherein the housing comprises a housing floor and a housing cover transversely to the rotor axis, and wherein an adjustment cage that is arranged between the housing floor and the housing cover, encloses the rotor and the vane and is adjustable transversely to the rotor axis is provided in the housing, characterized in that the housing and the adjustment cage delimit a pressure chamber connected fluidically to the pressure side, wherein a restoring element is provided, which pushes the adjustment cage into a base end position, and wherein the adjustment cage is deflected from the base end position if a limit operating variable is exceeded in the pressure chamber; and a switchover valve arranged downstream of the pressure side for fluidically connecting the pressure side to a first pressure connection or a second pressure connection, wherein the second pressure connection is connected to a pressure consumer in such a way that, when the pressure side is fluidically connected to the second pressure connection and when the limit operating variable is exceeded, the adjustment cage is deflected from the base end position in the pressure chamber.

17. The system according to claim 16, characterized in that the first pressure consumer is a cooling circuit with a heat exchanger, and/or in that the second pressure consumer is a pressure accumulator.

18. A method for operating a system comprising a vane pump with a suction side and a pressure side, with a housing and with a rotor, which is supported in the housing so as to be rotatable about a rotor axis and carries at least one vane supported movably in a radial direction, wherein the housing comprises a housing floor and a housing cover transversely to the rotor axis, and wherein an adjustment cage that is arranged between the housing floor and the housing cover, encloses the rotor and the vane and is adjustable transversely to the rotor axis is provided in the housing, characterized in that the housing and the adjustment cage delimit a pressure chamber connected fluidically to the pressure side, wherein a restoring element is provided, which pushes the adjustment cage into a base end position, and wherein the adjustment cage is deflected from the base end position if a limit operating variable is exceeded in the pressure chamber; and a switchover valve arranged downstream of the pressure side for fluidically connecting the pressure side to a first pressure connection or a second pressure connection, wherein the second pressure connection is connected to a pressure consumer in such a way that, when the pressure side is fluidically connected to the second pressure connection and when the limit operating variable is exceeded, the adjustment cage is deflected from the base end position in the pressure chamber, the method comprising the following steps: switching over of the switchover valve, so that the pressure side is connected to the pressure accumulator and the pressure accumulator is filled; deflection of the adjustment cage when the limit operating variable is exceeded and further filling of the pressure accumulator; switching over of the switchover valve so that the pressure side is connected to the cooling circuit, either after a set or settable time or when a limit pressure in or upstream of the pressure accumulator is exceeded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is an exploded view of an adjustable vane pump according to the invention;

[0033] FIG. 2 is a rear view of the adjustable vane pump according to FIG. 1;

[0034] FIG. 3 is a side view of the adjustable vane pump according to FIG. 1;

[0035] FIG. 4 is a cross section along the line IV-IV according to FIG. 3 with the adjustment cage in the base end position;

[0036] FIG. 5 is a cross section along the line IV-IV according to FIG. 3 with the adjustment cage in the deflection end position;

[0037] FIG. 6 is a schematic view of the adjustment cage in the base end position;

[0038] FIG. 7 is a schematic view of the adjustment cage in the deflection end position;

[0039] FIG. 8 is a circuit diagram of a system according to the invention with the adjustment cage in the base end position; and

[0040] FIG. 9 is a circuit diagram of a system according to the invention with the adjustment cage in the deflection end position;

[0041] FIG. 10 shows the efficiency of the electric motor for driving the vane pump according to FIG. 1 plotted against its speed.

DETAILED DESCRIPTION

[0042] FIG. 1 shows an adjustable vane pump 10, which comprises a two-part housing 12 with a box-shaped base part 13 and a housing cover 26. A rotor 18 arranged so as to be rotatable about a rotor axis 16 is provided in the pump chamber 14 (cf. also FIGS. 4 and 5). To rotate the rotor 18, said rotor is rotationally coupled by a rotor shaft 20. The rotor 18 is used to carry vanes 22 supported movably in a radial direction in the rotor 18. To rotate the rotor 18, an electric motor 19 is screwed onto the housing cover 26, wherein the rotor shaft 20 driven by the electric motor 19 extends through the housing cover 26 to the rotor 18.

[0043] In an axial direction, i.e. in the direction of the rotor axis 16, the pump chamber 14 is delimited by a first upper stop surface 24 and by a second, lower stop surface 27 formed parallel to this. The upper stop surface 24 is formed here by the housing cover 26; the lower stop surface 27 is formed by the housing floor 30 of the base part 13.

[0044] An adjustment cage 32 that is arranged between the housing cover 28 and the housing floor 30, encloses the rotor 18 and the vanes 22 and is adjustable transversely to the rotor axis 16 is provided in the housing 12.

[0045] The adjustment cage 32 as well as the housing cover 28 and the housing floor 30 enclose the pump chamber 14. The adjustment cage 32 and the rotor 18 with the vanes 22 are consequently located, when viewed in the axial direction, between the two stop surfaces 24 and 26.

[0046] As is clear in particular from FIGS. 1, 4 and 5, the radially outer vane tips of the vanes 22 rest on the inner wall of the adjustment cage 32. The rotor 18 is arranged eccentrically in the pump chamber 14. The rotor 18 consequently also assumes an eccentric position relative to the adjustment cage.

[0047] On rotation of the rotor 18, a pressure gradient arises in the pump chamber 14. The pump 10 consequently comprises a suction side 19 and a pressure side 21.

[0048] It is evident from FIGS. 1 and 2 that in the housing floor 30 a suction inlet 47 is provided on the suction side 19 and a pressure outlet 48 that is spatially separated therefrom is provided on the pressure side 21. The suction inlet 47 and the pressure outlet 48 extend in an axial direction through the housing floor 30 into the pump chamber 14. On rotation of the rotor 18 the fluid, in particular transmission or engine oil, is aspirated via the suction inlet 47 and conveyed via the pressure outlet 48 out of the pump 10. The pressure outlet 48 provided in the housing cover 30 opens into a pressure duct 49 (cf. FIGS. 8 and 9). The medium conveyed by the pump 10 can be supplied to the consumer in question via the pressure duct 49.

[0049] The adjustment cage 32, the base part 13 and the housing cover 28 delimit a pressure chamber 38 and a restoring element chamber 33, which can be clearly seen in FIGS. 4 and 5. The adjustment cage 32 is formed here so as to be cuboid. Together with the housing 12 two opposing cuboid sides consequently delimit the pressure chamber 38 and the restoring element chamber 33. The other four sides rest on the housing 12 in a sealing manner, so that the pressure chamber 38 is separated from the restoring element chamber 33 in a sealing manner. Suitable seals can also be provided for this purpose. The housing 12 is consequently also used as a guide for the adjustment cage 32.

[0050] As shown in FIGS. 6 and 7, the adjustment cage 32 can be adjusted transversely to the rotor axis 16 in the direction of the arrow 34.

[0051] In the restoring element chamber 33 two restoring elements 36 formed as restoring springs are provided, which push the adjustment cage 32 into the base end position, which is shown in FIGS. 6 and 7.

[0052] As is clearly evident from FIGS. 4 and 5, the restoring elements 36 extend perpendicularly to the rotor axis 16. The restoring elements 36 are further supported on the base part 13 on the one hand and on the adjustment cage 32 on the other. The adjustment cage 32 rests, in the base end position, against a first stop 52 on the housing side which is provided on the pressure chamber side and is formed by the base part 13 of the housing 12.

[0053] It is evident from FIGS. 6 and 7 that the pressure outlet 48 is fluidically connected to the pressure chamber 38 by a fluid line 41. As a result the pressure side 21 is connected fluidically to the pressure chamber 38. The fluid line extends from the pressure outlet 48 of the vane pump 10 outside the housing 12 to an opening 51 (cf. FIG. 1) in the housing 12 and extends through this opening 51 into the pressure chamber 38. The fluid conveyed by the pump 10, in particular oil, is thus not only pumped from the pressure outlet 48 to a consumer but also flows in the pressure chamber 38. An adjustment of the adjustment cage 32 takes place consequently solely depending on the pressure and the pressure force F.sub.p exerted thereby in the pressure chamber, exerted by the fluid conveyed by the pump 10.

[0054] If a limit pressure at the pressure outlet 48 and thus also in the pressure chamber 38 is exceeded, the pressure force F.sub.P exceeds the restoring force F.sub.R of the restoring elements 36 acting in the opposite direction, so that the adjustment cage 32 is deflected. In this case the adjustment cage 32 is moved either abruptly or continuously as the pressure increases in the pressure chamber 38 into a deflection end position, which is shown in FIGS. 5 and 7. In an abrupt adjustment, the deflection end position is assumed substantially immediately when the limit pressure is exceeded. In a continuous adjustment, the adjustment cage 32 is gradually moved into the deflection end position after the limit pressure has been exceeded as the pressure increases in the pressure chamber 38.

[0055] In the deflection end position the adjustment cage 32 rests on a second stop 54, which is provided on the restoring chamber side, and is formed by the base part 13 of the housing 12.

[0056] Due to adjustment of the adjustment cage 32, the eccentric position of the rotor 18 changes inside the adjustment cage 32 and thus the size of the pump chamber 14 also changes. In the base end position the pump chamber is crescent-shaped (cf. FIG. 6), if this were in the deflection end position (cf. FIG. 7) it would be annular. The conveying capacity of the pump changes accordingly.

[0057] In the base end position the conveying volume (displacement) of the pump 10 is approx. 2.5 ccm/rev, while the conveying volume in the deflection end position is 0.5 ccm/rev. The limit pressure here is between 2 and 5 bar, a corresponding counterforce F.sub.R is consequently applied by the setting elements 36. In the deflection end position the pump can apply a pressure of up to 40 bar to a pressure consumer.

[0058] Both in the base end position and on deflection of the adjustment cage 32 from the base end position and in the deflection end position, the electric motor 19 is operated at its nominal speed b of approx. 3500 rev/min. As is clearly evident from FIG. 10, the efficiency and thus also the available drive output are maximal at the nominal speed b. As a result, the electric motor 19 is operated only at one operating point b. The change in the pump characteristics, in particular of the conveyed fluid volume per minute, takes place solely via the internal deflection of the adjustment cage 32 from the base end position.

[0059] It would also be conceivable on the other hand to vary the speed quite easily within the nominal speed range a (cf. FIG. 10). In this case the efficiency is only slightly poorer than the maximum efficiency of the electric motor 19. Nevertheless, an adjustment of the speed to the low-pressure or high-pressure mode can take place.

[0060] FIGS. 8 and 9 show the arrangement of the vane pump 10 in a system 80. Here oil is conveyed from an oil sump 70 by the vane pump 10 to the pressure outlet 48 through a filter 71. A magnetic switchover valve 56 is connected downstream of the pressure outlet 48. This can be controlled in the same way as the electric motor 19 for driving the rotor 18 by a control device 58. By means of the switchover valve 56 the pressure side of the vane pump 10 can thus be connected on the one hand to a first pressure connection 60 or on the other hand to a second pressure connection 62 in a fluid-tight manner.

[0061] The second pressure connection 62 is connected to a pressure consumer 64 formed as a pressure accumulator. In particular, shift rods 75 in gear units can be moved by the oil of the pressure consumer 64. The first pressure connection 60 discharges into a heat exchanger 66 of a coolant circuit 69.

[0062] In the switching position shown in FIG. 8, the first pressure connection 60 is connected fluidically to the vane pump 10. In this case in low-pressure mode a comparatively large quantity of oil is conveyed at low pressure to cool a gear unit 73, for example.

[0063] In the fluid connection, shown in FIG. 8, of the cooling circuit to the vane pump 10, it can occur, on cold starting of the vehicle or in the event of soiling of the heat exchanger, that the oil to be conveyed is viscous such that a flow resistance is built up, which causes the limit pressure in the pressure chamber 38 to be exceeded. This causes the adjustment cage 32 to be deflected from the base end position. Due to this, the pump 10 advantageously switches to the high-pressure mode (requirement 2) with low conveying volume and thus builds up a sufficiently high pressure to convey the oil in the cooling circuit. As soon as the oil heats up with the operating duration of the vehicle, the flow resistance drops. Due to this, the pressure falls below the limit pressure in the pressure chamber 38 again, so that the restoring springs 36 move the adjustment cage 32 back into the base end position and thus oil in the low-pressure mode (requirement 1) is conveyed through the cooling circuit 69 to cool the gear unit 73.

[0064] According to FIG. 9, the second pressure connection 62 for filling the pressure accumulator 64 is connected in a fluid-tight manner to the vane pump 10 by switching over the switchover valve 56. The switchover takes place at regular set or at settable time intervals. On the other hand, this can also take place when the pressure in the pressure accumulator, measured by the pressure sensor 74, falls below a certain limit value.

[0065] The pressure accumulator 64 is then filled. To prevent a flow of oil from the pressure accumulator back into the vane pump 10, a non-return valve 68 is provided here. As the filling level of the pressure accumulator 64 increases, such a high pressure resistance is exerted on the pressure outlet 48 that the limit pressure in the pressure chamber 38 is exceeded. This is because the limit pressure is at approx. 2 bar and the pressure accumulator 64 is filled with oil up to approx. 40 bar. Exceeding the limit pressure causes the adjustment cage 32 to be deflected. The pump characteristics are changed thereby, so that the high-pressure mode (requirement 2) is assumed. The pressure accumulator 64 is topped up at high pressure in this case.

[0066] The control device 58 can measure, on the one hand, pressure values of the coolant circuit by means of a sensor 72 or, on the other hand, pressure values upstream of the pressure accumulator by means of the pressure sensor 74 and switch the switchover valve 56 in response to the values measured. Furthermore, the temperature in the oil sump 70 can be measured by the temperature sensor 76 and said sensor can switch the switchover valve 56 depending on these values.

[0067] An exemplary and particularly preferred embodiment of the invention then results as follows: to cool and lubricate the gear unit 73, the vane pump 10 is connected to the cooling circuit 69 by switching over the switchover valve 56 and is operated in low-pressure mode (requirement 1). To this end the pump 10 is operated at a pump volume of 2.857 ccm/rev in low-pressure mode at up to approx. 5 bar pump pressure by the electric motor 19 at a speed of 3500 rev/min and a torque of 0.227 Nm in order to convey 101/min of fluid. The adjustment cage is located in the base end position in this case. The speed of 3500 rev/min here corresponds to the nominal speed at which the electric motor 19 has its maximum efficiency and thus its maximum available drive output.

[0068] To fill the pressure accumulator 64, the vane pump 10 is initially connected thereto and is no longer connected to the cooling circuit 69. On filling of the pressure accumulator 64, a back pressure builds up, which quickly exceeds the limit pressure of 5 bar. As the pump pressure increases, the adjustment cage 32 is then deflected into the deflection end position. In the deflection end position the pump volume is 0.571 ccm/rev. The speed here is identical to the low-pressure mode and is 3500 rev/min. The torque is virtually identical to the low-pressure mode and is 0.364 Nm. In this high-pressure mode (requirement 2) 21/min of fluid is conveyed. The pressure accumulator is filled with oil up to approx. 40 bar.

[0069] According to the invention the vane pump 10 can consequently be operated at a requirement 1 (high volume flow rate with low pump pressure) and a requirement 2 (low volume flow rate with high pump pressure). The operating point of the electric motor 19 does not have to be changed in this case. The vane pump 10 is instead operated with the same operating point of the electric motor 19 for both requirement 1 and requirement 2.