Abstract: An aftermarket device for permitting an electric solenoid of a torque converter lock-up clutch to be selectively actuated and deactuated by a vehicle electronic control module only when the vehicle is operating above a predetermined vehicle speed, or is operating in the high gear ratio. The device includes a switching transistor in the supply voltage side of an electric solenoid which enables the solenoid by coupling a source voltage to the solenoid from a brake switch. The switching transistor can either be an "NPN" or an "PNP" type depending upon whether a pressure activated contact switch in the transmission is "normally open" or "normally closed".

Abstract: A lockup clutch of an automatic transmission is controlled so that no shock is produced while the vehicle is running within a predetermined gear stage. The automatic transmission includes a fluid coupling; a lockup clutch provided in the fluid coupling; a shift selector for selecting a range; a vehicle speed sensor for detecting vehicle speed, and a throttle opening sensor for detecting throttle opening. A control unit determines a gear stage in accordance with the selected range, the vehicle speed and the throttle opening, decides a shift, produces a shifting output signal, decides ON or OFF for the lockup clutch in accordance with the selected range, the vehicle speed and the throttle opening, and produces a lockup ON/OFF output signal. An oil pressure circuit actuates solenoid valves in response to the shifting output signal and the lockup ON/OFF output signal of the control unit.

Abstract: A hydraulic control circuit for an automatic transmission which has a plurality of hydraulic type frictional engagement elements for switching gear stages and a lockup clutch juxtaposed to a hydraulic power transmission device for transmitting engine power to the gearing. The hydraulic control circuit includes a lockup relay valve for switching oil pressure between an application side oil chamber and a release side oil chamber of the lockup clutch to apply and release the lockup clutch and a lockup switching valve for switching the lockup relay valve. A lockup control valve functions to increase the pressure difference between the application side oil chamber and the release side oil chamber at the time of application of the lockup clutch, as a signal pressure rises. A transient pressure control valve controls the transient pressure of a hydraulic frictional engagement element in accordance with the signal pressure.

Abstract: An apparatus for controlling a lock-up clutch disposed between an engine and an automatic transmission of a motor vehicle, including a slip control device for controlling a slip control pressure to be applied to the lock-up clutch to control the amount of slip of the lock-up clutch, a shift detector for detecting a shifting action of the transmission during deceleration of the vehicle, and a pressure changing device which commands the slip control device, upon detection of a shifting action of the transmission during vehicle deceleration, to change the slip control pressure a predetermined time prior to completion of the shifting action, for reducing an engaging force of the lock-up clutch to a value lower than a value corresponding to the amount of slip of the lock-up clutch established when the transmission is not in the process of a shifting action, to reduce the shifting shock of the transmission.

Abstract: A system and method for controlling the bypass clutch of an automatic transmission includes an electronic microprocessor, an electronic memory accessible to the microprocessor, solenoid-operated bypass valve, pressure actuated bypass clutche, a variable force solenoid-operated bypass valve, a torque converter bypass friction clutch, and control algorithms that produce output signals to control the state of the solenoid-operated valve. The vehicle speed at which the bypass clutch engages and disengages, according to a reference schedule, is compensated for loss of engine torque at conditions that differ from the conditions at which the reference schedule is defined. Vehicle speed is compensated for torque variation with reference to the ratio of current calculated engine torque divided by current engine output torque.

Abstract: An apparatus is provided for use in a vehicle having an engine driven transmission which includes a plurality of gear ratios. The apparatus includes a sensor adapted to sense an operating parameter and responsively produce a parameter signal. A memory device includes a custom shiftpoint map for storing data which relates transmission gear ratio to the parameter signal. A programming device for allowing the custom shiftpoint map to be reprogrammed during vehicle operation. A controller is adapted to receive the vehicle speed signal, retrieve data from the custom shiftpoint map, and process the retrieved data and the parameter signal to produce a transmission control signal. An actuator is adapted to receive the transmission control signal and responsively control the transmission gear ratio.

Abstract: A lock-up clutch by way of which input/output shafts of a torque converter are operatively connected to each other is connected to an electronic type pressure control valve. During speed changing in a transmission, the problem of interruption of torque transmission can be solved by turning off the lock-up clutch at the time when filling of one of the speed changing clutches to be next brought into an operatively engaged state with hydraulic oil is completed. Hydraulic pressure (P.sub.t) in the torque converter is exerted on the back pressure portion of a piston of the lock-up clutch while hydraulic pressure (P.sub.t) in the torque converter is exerted on the proportional solenoid side of the pressure control valve, making it possible to reduce the initial hydraulic pressure. During speed changing, the lock-up clutch is not fully released from the engaged state but maintains its operative state at low pressure, causing shock from shifting the lock-up state to be reduced.

Abstract: A shift control system controls an automatic transmission of a vehicle wherein half-lock-up control for a lock-up clutch is executed when the running state of the vehicle is in a predetermined operative range.

Abstract: A system for scheduling gear ratio changes in an automatic transmission and controlling operation of a torque converter bypass clutch includes a microprocessor; electronic memory containing control algorithms, lookup tables, functions and constants; solenoid-operated shift valves, a variable force solenoid, friction clutches, brakes and sensors, and planetary gear units. A table of calibrated performance weighting factors (PWF) is used to alter reference schedules of gear ratio changes based on the extent to which high performance operation is desired rather than economy operation. The PWFs are used to adjust gear shift points based on inferences drawn from engine throttle position and time rate of change of throttle position. Hydraulic pressure supplied to the friction elements and the schedule of unlocked and modulated operation of the torque converter are adjusted from reference schedules and pressures on the basis of PWF values.

Abstract: In a driving zone where a torque converter is to be locked up, a lockup force of a lockup clutch is weakened in the deceleration driving state compared with that in the non-deceleration driving state. Moreover, during transition from the deceleration driving state to the non-deceleration driving state, increase control of the lockup force is forcedly delayed for a predetermined time. By this, during acceleration from the deceleration driving state, the clutch is made to slip with a rapid increase in engine output torque and a rise in the engine output torque is buffered by the lockup clutch.