Abstract: A lock-up control system for an automatic transmission of an automotive vehicle controls operation of a lock-up clutch for mechanically engaging the automatic transmission with the engine to enable transmission of a driving force output from the engine to the automatic transmission. An engaging force of the lock-up clutch is controlled in an predetermined operating region of the automotive vehicle, which is determined based on operating conditions of the automotive vehicle and the engine, in such a manner that an amount of slip of the lock-up clutch becomes equal to a desired value. An engaging force control amount for controlling the engaging force of the lock-up clutch is learned when the automotive vehicle is traveling in the predetermined operating region with the automatic transmission being in a predetermined speed position, and a learned value thus obtained is stored.

Abstract: A vehicle automatic transmission control system in which the clutch is controlled in a slipping state if a torque converter is locked up when the gear shift command is not output. When the engine speed fluctuates, the fluctuations pass through the transmission and wheels and act on the ground to produce a reaction which passes back through the wheels and vehicle body and acts on the passengers as surging. In the prior art, this surging is prevented by slip-controlling the lockup clutch. This complicates the hydraulic control circuit. In the subject control, therefore, the clutch is slip-controlled even when no gearshift is in progress so as to absorb surging by slipping the clutch, not by the torque converter as in the prior art. As a result, it suffices to control the lockup clutch L of the torque converter between only two positions, one for complete lockup and one for complete release, rendering the structure of the hydraulic control circuit simple.

Abstract: A control system for an engine-CVT drivetrain controls torque transmitting capacity of a lock-up clutch in response to drop of operator's power demand to keep hydraulic drive of a fluid coupling operable until a predetermined period of time passes after the subsequent increase of operator's power demand.

Abstract: In order to prevent an increase in engine noise during a kick-down, a timer is set concurrently with a downshifting. When the throttle opening degree becomes equal to or larger than a threshold value YTHNST by a rapid depression of an accelerator pedal before lapse of a predetermined time, a lock-up clutch of a torque converter is brought into an engaged state, thereby preventing a revolution speed of an engine from rising rapidly in order to alleviate the engine noise. After the throttle opening degree TH becomes smaller than the threshold value YTHNST and the engagement of the lock-up clutch is released, the lock-up clutch is not brought into the engaged state even if the throttle opening degree TH again becomes equal to or larger than the threshold value YTHNST. Also, when the throttle opening degree TH becomes equal to or larger than the threshold value YTHNST after lapse of the predetermined time, the lock-up clutch is not brought into the engaged state.

Abstract: A controller device for vehicle automatic transmission including oil-pressure driven type friction elements controls the duty factors of the solenoid valves for the respective friction elements involved in the gear shift. In the first control interval A, the duty factors are controlled in accordance with predetermined patterns, such that the friction elements engage with predetermined amounts of slip at the actual beginning of the gear shift. The first interval A is terminated either when a change in the rotational speed of the input shaft of the automatic transmission is detected or when a predetermined length of upper limit for the first interval A expires. When the first interval A terminates, the second control interval B begins, and the duty factors are controlled by a feedback control method.

Abstract: A locking-up hydraulic pressure control device of an automatic transmission comprises a memory, a controller, a second memory, and a time schedule management. The memory stores a hydraulic pressure control time schedule from the beginning of shift operation to the end. The controller means controls a locking-up hydraulic pressure in accordance with said hydraulic pressure control time schedule to be provided to a lock-up clutch that mechanically connects and disconnects a pump impeller of a torque converter of said automatic transmission connected to an engine and a turbine runner connected to transmission gears. The second memory stores a time schedule of engine revolution during a shift operation. The time schedule management means resets said hydraulic pressure control time schedule higher pressures than the former pressures in case if engine revolution exceeds said time schedule of engine revolution during the shift operation by a certain given limit.

Abstract: A multiple ratio automatic transmission having a hydrokinetic torque converter in an automotive vehicle driveline wherein the torque converter has a controllable bypass clutch and wherein provision is made for changing the clutch capacity during a ratio change to reduce undesirable torque fluctuations in the driveline, thus improving shift quality while maintaining optimum hydrodynamic torque converter efficiency.

Abstract: An electronic transmission coastdown shift control method in which the transmission controller has the capacity to predict timing of apply element application. The control method of the present invention improves the shift sequence by accurately prefilling the apply element. The transmission controller vents the release element when apply element application is imminent and controls the application of the oncoming element to achieve a controlled element exchange for a smooth coastdown shift. A duty cycle is then applied to complete the oncoming element application with a soft yet quick application and control the engagement of the oncoming element. The identification of the application point of the oncoming element enables the apply element fill volume to be learned during coastdown shifts. It also enables the calculation of a line pressure correction factor necessary in accurately predicting application of the apply element. Anticipation of a coastdown tip-in condition is also provided.