Drive device for driving an oil pump

Abstract

A drive device for driving an oil pump (12) using a drive element (3), the oil pump (12) and the drive element (3) comprising axes (13, 8) that are arranged parallel to and offset from each other. It is suggested that the drive element (3) comprises an internal gear (11) with internal gearing and the pump (12) comprises a driving wheel (14) with outer gearing, and that the pump (12) can be driven by engaging the gears of the internal gear (11) and the driving gear (14).

Description

This application claims priority from German Application Serial No. 10 2004 045 425.6 filed Sep. 18, 2004.

FIELD OF THE INVENTION

The invention relates to a drive device for driving an oil pump.

BACKGROUND OF THE INVENTION

Drives for oil pumps in motor vehicles with automatic transmissions are known in various designs. The oil pump serves the supply of pressurized oil to the control elements of the transmission and of lubricating oil to the bearings and gear wheels. Beyond that, the converter is also supplied with hydraulic oil by way of an oil pump. The most prevalent are the so-called converter neck oil pumps, as they became known for example by WO 93/11376 by the applicant or DE 37 17 255 C2. Such oil pumps are disposed coaxially to the shaft of the converter on the transmission housing and are driven by the so-called neck of the pump shaft, i.e. with the input speed of the converter. These oil pumps are typically implemented as internal gear pumps, so-called crescent pumps or as radial piston pumps. A typical design for a crescent pump is disclosed in the applicant's DE 102 27 314 A1; here an inner pump wheel with outer gearing is driven by the converter neck and meshes with the inner gearing of an internal pump gear while forming a sickle-shaped gap, the so-called crescent. These coaxial designs have the disadvantage that they require axial space—between the converter and transmission—which is typically very scarce.

DE 43 42 233 B4 discloses an oil pump drive device in non-coaxial, but instead in an axially displaced configuration, i.e., the pump drive shaft is offset parallel to the axis of the engine drive shaft and is driven by way of a spur gear step. This configuration also requires axial space, which is determined by the width of the spur gear toothing.

It is the object of the present invention to design a drive device for driving an oil pump of the above-mentioned kind such that the least possible space is required.

SUMMARY OF THE INVENTION

It is provided in that the oil pump is driven by an internal gear, which is connected directly to the drive element in accordance with the invention. The driving gear wheel of the pump drive shaft is located within the internal gear. This results in a space-saving advantage. The drive element can be designed as a starting element, beneficially as a hydrodynamic converter, as a starting clutch or twin clutch, which is known in particular for motor vehicle transmissions from the state of the art. Moreover, the drive element can be designed as a vibration-isolating element, for example, as a torsional oscillation damper or as a dual mass flywheel. The internal gear with internal gearing for driving the oil pump can be attached to these drive elements without difficulty. Another advantage is that the oil pump can be driven at a higher rotational speed, due to the increased gear ratio, between the internal gear and driving gear wheel of the pump shaft. In this way, a pump having a smaller volumetric displacement can be used, i.e., a pump with lower manufacturing costs and lower space requirement. Beyond that, favorable ratios of the pump width to the diameter can be selected so that the pump efficiency increases.

According to a beneficial embodiment of the invention, the oil pump is used for supplying hydraulic medium to an automatic transmission for motor vehicles, i.e., for supplying pressure oil for the control elements of the transmission, for supplying lubricating oil for the gear wheels and bearings and for supplying pressure oil to the converter circuit. Beneficially these pumps are designed as outer gear wheel, inner gearwheel, piston pumps, especially radial piston pumps or vane cell pumps.

According to a beneficial embodiment of the invention, the internal pump gear is driven by the internal gear of the drive element, e.g., the converter pump wheel, when using an internal gear pump, i.e., a crescent pump. The internal gearing of the driving internal gear thus engages in the outer gearing of the driven internal pump gear. This results in the advantage of a particularly compact design.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is an oil pump drive device driven by a hydrodynamic converter according to the invention; and

FIG. 2 is the oil pump drive device driven by a clutch according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows in a schematic illustration of the top half of an automatic transmission 1 for a motor vehicle with a housing 2 illustrated with dotted lines, which holds a converter 3 as well as a transmission (not illustrated) consisting of sets of wheels and control elements. The converter 3—as is known—comprises a pump wheel 6 driven by a drive shaft 5, a turbine wheel 7 with a turbine shaft 8 and a guide wheel 9, which is supported in relation to a housing wall 10 by way of a free wheel 9a. An internal gear 11 comprising internal gearing 11a is attached to the pump wheel 6 of the converter 3. Within the transmission housing 2, an oil pump 12 is arranged, which comprises a drive shaft 13 and a driving gearwheel 14 with outer gearing 14a. The drive shaft 13 of the pump 12 is arranged in an offset fashion in relation to the drive shaft (turbine shaft) 8 of the gearshift 4. The pump wheel 6 drives the driving gear wheel 14, and hence the pump 12 by way of the internal gear 11. The different number of teeth on the internal gear 11 and the driving gear wheel 14 result in a speed-increasing gear ratio so that the pump 12 is driven at a higher rotational speed than the speed of the pump wheel 6 and hence the speed of the drive shaft 5. The drive shaft 5—as is known—is driven by an engine (not illustrated) of the motor vehicle, i.e., at the engine speed. The rotational speed of the oil pump 12 is, therefore, higher than the respective engine speed. The pump 12 can be designed as an outer gear wheel or inner gear wheel pump, as a piston or vane cell pump. In a variation (not illustrated), the pump 12 is designed as a crescent pump, i.e., an internal gear wheel pump, comprising an internal pump gear, which assumes the function of the driving gear wheel 14, i.e., is driven by the internal gear 11 and its internal gearing 11a.

FIG. 2 shows another embodiment of the invention wherein, instead of the converter 3 from FIG. 1, a different drive element, namely, a clutch, e.g., a multi-disk clutch 20 is used, which is driven by way of a drive shaft 21 by an engine (not illustrated) of the motor vehicle. In a housing 22 illustrated with dotted lines, a gear transmission is accommodated, which is driven by an output shaft 23 of the clutch 20. The clutch 20 can also be designed as a twin clutch, which is indicated by a dotted internal gear 24. The clutch 20 comprises a housing 20a, which is connected to an internal gear 25. In the transmission housing 22, an oil pump 26 of a drive shaft 27 and with a driving gear wheel 28 is arranged, which is driven by the internal gear 25. The pump 26 and its drive shaft 27 are arranged axially displaced in relation to the shafts 23, 24.

The oil pump drive using an internal gear according to the invention—as described in the two embodiments—is preferably used in motor vehicles, but is not limited to this type of application. Instead of the described starting elements—converter or clutch—the internal gear can be attached; also the other drive elements in the drive train, e.g., to a torsional oscillation damper or a dual mass flywheel, for the purpose of driving the oil pump.

Reference Numerals

• • 1 automatic transmission of a motor vehicle
  • 2 transmission housing
  • 3 converter
  • 4 gearshift
  • 5 drive shaft of converter
  • 6 pump wheel
  • 7 turbine wheel
  • 8 turbine shaft
  • 9 guide wheel
  • 9a free wheel
  • 10 housing wall
  • 11 internal gear
  • 11a internal gearing
  • 12 oil pump
  • 13 pump drive shaft
  • 14 driving gear wheel
  • 14a outer gearing
  • 20 clutch (twin clutch)
  • 20a clutch housing 21 clutch drive shaft
  • 22 transmission housing
  • 23 clutch output shaft
  • 24 internal gear (for twin clutch)
  • 25 internal gear
  • 26 oil pump
  • 27 pump drive shaft
  • 28 driving gear wheel

Claims

1-11. (canceled)

12. A drive device for driving an oil pump (12, 26) using a drive element, the oil pump and the drive element have axes that are arranged parallel to and offset from each other, the drive element having an internal gear (11, 25) with internal gearing, and the oil pump (12, 26) having a driving wheel (14, 28) with outer gearing, the oil pump (12, 26) can be driven by engaging the gears of the internal gear (11, 25) and the driving gear (14, 28).

13. The drive device according to claim 12, wherein the drive element is designed as a starting element (3, 20).

14. The drive device according to claim 13, wherein the drive element is designed as one of a hydrodynamic converter (3, 6, 7, 8, 9), a starting clutch (20) and a twin clutch (24).

15. The drive device according to claim 12, wherein the drive element is designed as a vibration-isolating element.

16. The drive device according to claim 15, wherein the vibration-isolating element is designed as one of a torsional oscillation damper or a dual mass flywheel.

17. The drive device according to claim 12, wherein the oil pump (12) is designed as a pump for supplying an automatic transmission (1, 2, 3, 4) for motor vehicles with hydraulic medium.

18. The drive device according to claim 17, wherein the oil pump (12, 26) is designed as an outer gear wheel pump.

19. The drive device according to claim 17, wherein the oil pump (12, 26) is designed as an inner gear wheel pump, especially a crescent pump.

20. The drive device according to claim 17, wherein the oil pump (12, 26) is designed as a piston pump, especially a radial piston pump.

21. The drive device according to claim 17, wherein the oil pump (12, 26) is designed as a vane cell pump.

22. The drive device according to claim 19, wherein the internal gear wheel pump comprises an internal pump gear, which is designed as a driving gear with outer gearing and engages in the internal gear (11, 25) of the drive element (3, 20).

23. A drive device for driving a flow of pressurized oil, the drive device comprising:

an oil pump (12, 26) having driving wheel (14, 28) with outer gearing which rotates about a pumping axis; and

a drive element drive element (3, 20) having an internal gear (11, 25) with internal gearing, the internal gear rotates about a driving axis, the driving axis being parallel to and offset from the pumping axis, the oil pump (12, 26) being driven by engaging the outer gearing of the oil pump (12, 26) with the internal gear (11, 25) of the drive element drive element (3, 20).

24. The drive device according to claim 23, wherein the drive element is one of a starting element (3, 20), a hydrodynamic converter (3, 6, 7, 8, 9), a starting clutch (20) and a twin clutch (24).

25. The drive device according to claim 23, wherein the drive element is a vibration-isolating element.

26. The drive device according to claim 25, wherein the vibration-isolating element is one of a torsional oscillation damper or a dual mass flywheel.

27. The drive device according to claim 23, wherein the oil pump (12) is a pump for supplying an automatic transmission (1, 2, 3, 4) of a motor vehicle with a hydraulic medium.

28. The drive device according to claim 27, wherein the oil pump (12, 26) is an outer gear wheel pump.

29. The drive device according to claim 27, wherein the oil pump (12, 26) is an a crescent pump.

30. The drive device according to claim 27, wherein the oil pump (12, 26) is a radial piston pump.

31. The drive device according to claim 27, wherein the oil pump (12, 26) is a vane cell pump.

32. The drive device according to claim 29, wherein the crescent pump has an internal pump gear, which is a driving gear with outer gearing and engages in the internal gear (11, 25) of the drive element (3, 20).