Abstract: A vehicle equipped with four-wheel drive has a transfer case including a center-differential which delivers driving power to both front and rear axle assemblies when needed and is shiftable between a two-wheel and a four-wheel drive mode of operation and between a differential-locked and a differential-unlocked drive mode of operation. A free wheeling drive mechanism with a clutch member is incorporated in an output shaft of an axle differential in association with wheels non-driven in the two-wheel drive mode of operation and is adapted to disconnect when the vehicle is in the two-wheel drive mode of operation. A controller causes a forced drive mode shift of the center-differential from the four-wheel differential-underlined drive mode of operation either to the four-wheel differential-locked or to the two-wheel drive mode of operation when the disconnection of the free-wheeling drive mechanism is detected while the vehicle is in the four-wheel differential-unlocked drive mode of operation.

Abstract: In an automatic transmission control system, completion of gear-shifting is detected on the basis of both the rate of change in rotational speed of the output shaft of the torque converter and the rotational speed at which the output shaft of the torque converter is expected to rotate. That is, a rotational speed range within which the rotational speed of the output shaft of the torque converter is expected to fall upon completion of the gear-shifting is determined taking into account the rotational speed of the output shaft of the torque converter upon initiation of the gear-shifting and the gear ratio, and it is determined that the gear-shifting is completed when the rotational speed of the output shaft of the torque converter falls within the predetermined rotational speed range and the rate of change in rotational speed of the output shaft of the torque converter is reduced below a predetermined value.

Abstract: An engine has an output shaft which is connected with a generator and a motor. A control device is provided to operate the generator in a high output torque period and to operate the motor in a low output torque period in an operating cycle of the engine. Thus, the generator applies a negative torque to the output shaft whereas the motor applies a positive torque to the output shaft to thereby moderate the output torque fluctuations.

Abstract: A lock-up control system for an automatic transmission including a torque converter coupled with an engine, a power transmitting gear arrangement controlled by a gear ratio control device in accordance with a shifting up or down signal, and a lock-up clutch provided for locking up the output shaft of the torque converter to the output shaft of the engine. The lock-up control system comprises lock-up operation control apparatus causing the lock-up clutch to be in its inoperative state when the gear ratio control device performs the control with the shifting up or down signal, and lock-up command device for preventing the lock-up operation control apparatus from causing the lock-up clutch to be in its inoperative state until a predetermined reductive variation in the speed of the output shaft of the torque converter arises after the shifting up signal is supplied to the gear ratio control device under the condition in which the lock-up clutch is in operation.

Abstract: A vehicle automatic transmission including a torque converter, a multiple stage transmission gear mechanism connected with the torque converter and a hydraulic control circuit for automatically selecting one of gear stages of the transmission gear mechanism. The hydraulic control circuit includes a kickdown control device which functions to shift down the gear mechanism when the engine control foot pedal is substantially fully depressed. Depending on the vehicle running condition, the kickdown control device shifts down the gear mechanism by two gear stages. The hydraulic circuit includes control circuit which functions to shift down the gear mechanism at first by one gear stage and then by a further one stage in sequence when a two stage shift down is required.

Abstract: A vehicle automatic transmission including a torque converter, a multiple stage transmission gear mechanism connected with the torque converter and a hydraulic control circuit for automatically selecting one of gear stages of the transmission gear mechanism. The hydraulic control circuit includes a kickdown control device which functions to shift down the gear mechanism when the engine control foot pedal is substantially fully depressed. Depending on the vehicle running condition, the kickdown control device shifts down the gear mechanism by two gear stages. The hydraulic circuit includes control circuit which functions to shift down the gear mechanism at first by one gear stage and then by a further one stage after a certain time delay when a two stage shift down is required.

Abstract: An exhaust gas purifying system for an automobile engine including at least first and second engine cylinder has a shutter valve for interrupting the supply of a combustible air-fuel mixture to the first engine cylinder during a particular engine operating condition, a three-way electromagnetically operated valve for controlling the operation of the shutter valve, and a secondary air supply unit including a switching valve for selectively supplying a secondary air to a portion of an exhaust passage upstream of at least one catalyst unit disposed in the exhaust passage.