Rotary expansible chamber devices – Moving cylinder – Rotating
Reexamination Certificate
1998-12-02
2001-02-06
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Moving cylinder
Rotating
C418S206400
Reexamination Certificate
active
06183229
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to hydraulic gear machines, such as pumps or motors, especially internal gear machines or spur gear machines of the type having a first gear which is rotatably journalled in a housing and a second gear which drives the first gear, as well as with at least one pressure building slot which is provided in the housing.
Hydraulic gear machines of the above outlined character are known, for example, from published German patent application Serial No. 2942417, U.S. Pat. No. 4,472,123 and published German patent application Serial No. 1553014. These gear machines have pressure building slots which are provided in the axial plates of the housing and, in a plan view, have a triangular outline. The pressure building slots in the axial plates of the housing in a gear machine serve to ensure a more uniform pressure application or pressure rise which is effected all the way to a plenum chamber and, in the event that the gear machine is used as a pump, there takes place a pressure rise and a rise in the rate of delivery from a suction chamber to a plenum chamber. When such gear machine is in use, it conveys a fluid from the suction chamber to the plenum chamber.
When such gear machines are used as pumps for motor vehicle aggregates, and especially for the transmissions of motor vehicles, such as for continuously variable speed transmissions with pulleys employing conical flanges, for example to convey a fluid, such as oil, from a sump to act upon adjusting members and/or for lubrication and/or cooling, the pump draws from the sump—during certain stages of operation of the vehicle—oil which contains a relatively high percentage of air, for examples a mixture of air and oil whereas, during other stages of operation of the vehicle, there is conveyed oil or an oil-air mixture which contains a relatively low percentage of air.
In known prior art pumps, the above brings about the drawback that the preliminary compression or the regulation of pressure by way of pressure building slots which—when looked at from above—have a triangular outline, and when the oil contains a relatively high percentage of air, takes place abruptly, i.e., in response to a relatively small angular displacement of the pinion. On the other hand, when the oil contains a relatively small percenage of air, the regulation of pressure takes place in response to a relatively larger angular displacement of the pinion, namely an angular displacement corresponding to the extension of the pressure building slot.
Pressure equalization during a relatively small angular displacement when the oil contains a high percentage of air entails a rather unsatisfactory acoustic behavior of the pump because, when the percentage of air in oil is relatively high, this causes the pressure rise to take place at a relatively high speed which, in turn, generates pressure waves causing a reduced acoustic quality.
OBJECT OF THE INVENTION
An object of the invention is to provide a hydraulic gear machine which exhibits improved acoustic characteristics by causing relatively low-velocity pressure rises even if the percentage of air or outside air in the oil to be conveyed varies, for example, under different operational conditions.
SUMMARY OF THE INVENTION
This object is achieved in the novel hydraulic gear machine by the provision of at least one pressure building slot which is of a multistage design and has at least two sections, an increase of the cross sections of individual sections taking place at different rates as a function of their extension. The extension can be interpreted as the length of the slot and/or for example also the extent of angular displacement of the gear which sweeps over or rotates along the slot.
Furthermore, it is possible to achieve the object in a hydraulic gear machine, such as a pump or motor, with a first gear which is rotatably journalled in the housing and a second gear which drives the first gear, with at least one filler piece disposed in a cavity between the first and second gears and a filler pin serving as an abutment for the filler piece, as well as with at least one pressure building slot provided in the housing. The slot is of a multistage design and comprises at least two sections with the cross sections of individual sections increasing at different rates as a function of their extension. If one employs conventional pressure building slots, an increase of the slots, as considered along their extension, is uniform in that each slot has a triangular shape or the area of the slot is even constant along its extension.
In accordance with another inventive concept, it is advisable that at least one pressure building slot comprise at least two first and second sections, the first sections of the pressure building slot exhibiting a divergent cross section and the second sections of the pressure building slot exhibiting a substantially constant cross section.
It is also particularly advantageous, in a hydraulic gear machine with a first gear which is rotatably journalled in a housing and a second gear which drives the first gear, with at least one filler disposed between the first and second gears and a filler pin serving as an abutment for the filler, as well as with at least one pressure building slot provided in the housing, if the at least one pressure building slot comprises first and second sections, the first sections of the pressure building slot having a divergent cross section and the second sections of the pressure building slot having an essentially constant cross section.
It is equally advisable that at least one pressure building slot comprise at least two sections having essentially different cross sections.
Furthermore, it is advisable that the first gear be an internally toothed hollow gear and the second gear constitute an externally toothed pinion.
It is also of advantage if each of the first and second gears constitutes an externally toothed gear.
It is further particularly advantageous if the hydraulic gear machine is provided with a radially inner and a radially outer pressure building slot.
It is equally advisable if at least one pressure building slot comprises three different sections.
Furthermore, it can be of advantage in accordance with a further embodiment of the invention if the filler consists of two filler portions and pressure zones are formed between the filler portions by seals, at least some of the pressure zones being connected, by a single channel, with a section of the pressure building slot.
In accordance with a further embodiment, it is of particular advantage if at least some plenum chambers are conected, by a single channel, with a section of a pressure building slot. The plenum chambers can be provided in the housing and/or in the axial plates.
The invention will be described, in greater detail, by way of example and without limiting its broadest aspects, with reference to the drawings,
REFERENCES:
patent: 3890066 (1975-06-01), Eckerle
patent: 3912427 (1975-10-01), Eckerle et al.
patent: 4132514 (1979-01-01), Eckerle
patent: 4472123 (1984-09-01), Eckerle et al.
patent: 4740142 (1988-04-01), Rohs et al.
patent: 5499910 (1996-03-01), Hundt et al.
patent: 1553014 (1969-08-01), None
patent: 29 42 417 A1 (1981-08-01), None
patent: 1 453 318 (1976-10-01), None
Darby & Darby
Denion Thomas
LuK Getriebe-System GmbH
Trieu Thai-Ba
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