Interrelated power delivery controls – including engine control – Brake control – Sensed condition responsive control of engine of brake
Reexamination Certificate
2000-03-15
2001-09-18
Marmor, Charles A (Department: 3681)
Interrelated power delivery controls, including engine control
Brake control
Sensed condition responsive control of engine of brake
C477S094000, C477S139000, C477S144000, C477S210000
Reexamination Certificate
active
06290627
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control unit of an automatic transmission which provides speed reduction control with good responsiveness to a speed reduction demand by a driver of the vehicle.
2. Description of Related Art
Speed reduction responsive to a speed reduction operation by a driver of a vehicle, such as a sudden release of the accelerator, braking or the like, is conventionally provided by a control system which monitors reduction in vehicle speed during brake operation, performs a down-shift operation when it is judged that the reduction in speed has reached a predetermined large value, and effects speed reduction by engine braking. However, with this conventional control system, there is a time delay between depression of the brake and the reduction in speed reaching the predetermined large value, and a down-shift operation cannot be performed during that time delay. Accordingly, an undesirably long time delay occurs before engine braking is actually provided by a down-shift operation after the driver demands the speed reduction, i.e., the system does not provide good responsiveness.
Further, since the speed change operation is generally performed based on a speed change map, an up-shift operation is performed responsive to an accelerator OFF operation. There are times when a down-shift operation may be performed due to the reduction in speed becoming equal to or greater than a predetermined value. In this case, the up-shift operation and the down-shift operation are both performed within a short time interval, thereby causing discomfort to the driver.
SUMMARY OF THE INVENTION
In view of the foregoing problem, an object of the present invention is to provide a control unit for an automatic transmission which can perform proper down-shift control with superior responsiveness to a speed reduction operation by a driver.
Accordingly, the present invention provides a control unit for an automatic transmission connected to a vehicle engine which includes speed reduction requirement judging means for judging whether or not there is a speed reduction demand based on an accelerator releasing operation by a driver, brake operation detecting means for judging whether or not a first time interval between full release of the accelerator and operation of the brake is within a predetermined time range, up-shift operation inhibiting means for inhibiting an up-shift of the transmission when the speed reduction requirement judging means judges that there is a speed reduction demand, and down-shift executing means for executing a down-shift of the transmission when the brake operation detecting means judges that the brake was operated (engaged) within the predetermined time range.
Further, the up-shift inhibiting means inhibits (prevents) an up-shift until a second time interval has passed with the accelerator in an idle state, when the brake is not depressed within the predetermined time range.
The up-shift inhibiting means prevents an up-shift until the accelerator is depressed, when the brake is not depressed within the predetermined time range.
Further, the up-shift inhibiting means prevents an up-shift until the speed change is judged completed based on the normal speed change map, when the brake is depressed after the predetermined time has passed with the accelerator in the idle state.
In accordance with the present invention, when the speed reduction requirement judging means judges, based on release of the accelerator, that there is a speed reduction demand by the driver, the up-shift inhibiting means inhibits the up-shift operation of the transmission so that it is possible to prevent a speed reduction force on the vehicle from being reduced due to the up-shift operation. Further, when the brake is operated within the predetermined time after the accelerator is released, the down-shift operation is executed so that it is possible to effectively provide the engine brake by the down-shift operation. Also, it is possible to prevent an up-shift and a down-shift from being continuously performed within a short time so as to cause discomfort to the driver.
Further, by setting the second predetermined time interval, an up-shift is not inhibited indefinitely, and a normal speed change may be smoothly performed after the second predetermined time interval has lapsed.
Also, when the driver quits the speed reduction operation and again depresses the accelerator, an up-shift is inhibited until the accelerator is depressed so that it is possible to rapidly move to the acceleration operation.
Further, when the brake is depressed after the predetermined time has passed in the idle state, an up-shift is inhibited until there is a speed change judgment based on the normal speed change map, so that it is possible to prevent the discomfort to the driver that would otherwise be caused by a plurality of continuously performed speed change operations.
The teachings of Japanese Application H11-80479, filed Mar. 24, 1999, inclusive of specification, claims, drawings and summary, are incorporated herein by reference in their entirety.
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Kusafuka Muneo
Unoki Masamichi
Aisin Aw Co. Ltd.
Aisin AW Co., Ltd.
Ho Ha
Marmor Charles A
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