This application claims priority from German Application Serial No. 10 2004 045 425.6 filed Sep. 18, 2004.
The invention relates to a drive device for driving an oil pump.
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.
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.
The invention will now be described, by way of example, with reference to the accompanying drawings in which:
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
Number | Date | Country | Kind |
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10 2004 045 425.6 | Sep 2004 | DE | national |