Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1998-12-24
2001-06-26
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S053000, C477S157000, C477S156000, C180S367000
Reexamination Certificate
active
06253137
ABSTRACT:
The contents of Tokugan Hei 9-3548610, with a filing date of Dec. 25, 1997 in Japan, are hereby incorporated by reference.
FIELD OF THE INVENTION
This invention relates to an oil pump for a vehicle drive system wherein an engine and a motor/generator are connected to drive wheels via a continuously variable transmission.
BACKGROUND OF THE INVENTION
European Patent Application EP0788914-A3 published by European Patent Office in 1998 discloses a vehicle drive system which inputs an output torque of one or both of an engine and a motor/generator through a continuously variable transmission. This is the so-called parallel hybrid vehicle drive system.
The generator/motor in this system is driven as a motor when electrical force is supplied from the battery and outputs rotational torque to the drive wheels. On the other hand, when rotational torque is input from the drive wheels, it functions as a generator and charges the battery by performing so-called regenerative braking. The drive ratio of the continuously variable transmission, i.e., the ratio of the input and output rotation speeds of the transmission, varies depending on the vehicle speed and the throttle opening of the engine.
SUMMARY OF THE INVENTION
The continuously variable transmission in this system is a V-belt continuously variable transmission which varies the drive ratio depending on oil pressure. Oil pressure is supplied from an oil pump connected to the input shaft of the continuously variable transmission. Even when the input shaft rotates at a low speed, the oil pump must provide the required discharge for the operation of the continuously variable transmission. However, determining the capacity of the oil pump on the basis of this kind of standard leads to excessive pump discharges when the input shaft is rotating at a high speed and the energy used to drive the pump is wasted.
It is therefore an object of this invention to improve the efficiency of the energy used to drive the oil pump.
In order to achieve the above object, this invention provides an oil pressure supply device for a vehicle drive system. In this drive system, an engine and a first motor are connected to a drive shaft via an automatic transmission and the transmission varies drive ratio depending on an oil pressure.
The device comprises an oil pump, a second motor connected to the oil pump, and an electrical circuit for regulating a rotation speed of the second motor. The oil pump varies a discharge according to the rotation speed of the second motor. The device further comprises a sensor for detecting an operating state of the automatic transmission and a microprocessor.
The microprocessor is programmed to determine from the operating state whether or not the automatic transmission is varying the drive ratio, and to control the electrical circuit so that the rotation speed of the second motor is higher when the automatic transmission is varying the drive ratio, than when the automatic transmission is not varying the drive ratio.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.
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Patent Abstracts of Japan, abstract of A. Suzuki et al. “Oil Pressure Control Device for Transmission”, 7-174218, Nov. 7, 1995.
Abo Keiju
Kuroda Shojiro
Takahara Hideaki
Cuchlinski Jr. William A.
Foley & Lardner
Hernandez Olga
Nissan Motor Co,. Ltd.
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