US 5,667,458 AGranted

Lock-up control apparatus for automatic transmission

AssigneeNissan Motor Co., Ltd.

InventorsYasushi Narita, Yasuhiro Niikura, Noboru Hattori, Shusaku Katakura, Hisaaki Tohjima

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Abstract

A lock-up control apparatus for a vehicle automatic transmission enables an engine stalling prevention at the time of a sudden deceleration in the lock-up state of a torque converter without causing the slip of the torque converter before the sudden deceleration, and prevents effectiveness of the fuel consumption from being sacrificed by a fuel cut. A controller performs the change-speed control on an automatic transmission through shift solenoids and on the basis of a throttle opening and a transmission output speed, and also performs the lock-up control of the torque converter through a lock-up solenoid. During the coasting drive when the throttle opening is set close to zero, the controller sets the torque converter to have a minimum lock-up capacity through the lock-up solenoid within such a range that no slip occurs. When the sudden deceleration is carried out, the controller releases the lock-up, though this lock-up release is rapidly achieved with the minimum lock-up capacity thereby to avoid the engine stalling.

Claims8

Dependent claims

A lock-up control apparatus for an automatic transmission, including a torque converter which can be turned into a lock-up state by a lock-up clutch so that input and output elements of the torque converter are directly connected with each other, comprising:

a coasting drive detecting means for detecting a coasting drive including a deceleration operation of a vehicle;
a sudden deceleration detecting means for detecting a large deceleration rate above a predetermined value of the vehicle;
and
a coasting drive lock-up capacity controlling means for controlling an application capacity of the lock-up clutch to a minimum application capacity within such a range that a relative rotation is not generated between the input and output elements of the torque converter in a period when the deceleration rate of the vehicle is below the predetermined value during the coasting drive, in response to signals from both the detecting means,
wherein the coasting drive lock-up capacity controlling means comprises:
a reverse driving torque detecting means for detecting a reverse driving torque of an engine in a forward speed of the automatic transmission;
and
a coasting drive lock-capacity operating means for calculating a minimum application capacity of the lock-up clutch within such a range that the relative rotation is not generated between the input and output elements of the torque converter from the reverse driving torque detected by the reverse driving torque detecting means, thereby controlling the application capacity of the lock-up clutch by a command value corresponding with the application capacity calculated by the coasting drive lock-up capacity operating means.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/499,258Filed 7 Jul 1995
Priority: JP 6-1573258 Jul 1994
Granted: 16 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

F16H 61/143
Control of torque converter lock-up clutches: using electric control means
F16H 59/48
Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion: inputs being a function of acceleration
F16H 59/54
Inputs being a function of the status of the machine, e.g. position of doors or safety belts: dependent on signals from the brakes, e.g. parking…
F16H 2059/186
Dependent on the position of the accelerator pedal: coasting