Abstract: In an automatic transmission for a vehicle such as an automobile having a speed stage shifting mechanism including parallelly arranged first and second input clutches C1, C2 and adapted to selectively engage the first and second input clutches in three ways of engaging the first input clutch C1 with the second input clutch C2 being disengaged to provide a certain first speed stage (2nd speed stage), engaging the second input clutch C2 with the first clutch C1 being disengaged to provide a certain second speed stage (4th speed stage) and engaging both the first and second clutches C1, C2 to provide a certain third speed stage (3rd speed stage), a hydraulic control device has a first valve (3-4 shift valve) for switching over connection of the first input clutch C1 with a hydraulic pressure supply 274 and a drain 280, a second valve (2-3 shift valve) for exchanging connection of the second input clutch C2 and a fail safe port 260 with a hydraulic pressure supply 246 and a drain 252, 253, and a passage 268 for c

Abstract: For an automatic transmission for a vehicle such as an automobile having a speed stage shifting mechanism including parallelly arranged first and second hydraulically operated input clutches and adapted to provide the 3rd speed stage in which the first and second input clutches C.sub.1 and C.sub.2 are both engaged and the overdrive 4th stage in which the clutch C.sub.1 is disengaged and the clutch C.sub.2 is engaged, the engagement of the clutch C.sub.1 in the 3rd speed stage being not essential unless engine brake availability is required, a hydraulic control device has a hydraulic pressure supply control device for variably controlling speed of supply of a hydraulic pressure to the first input clutch C.sub.1 according to conditions for engaging the first input clutch such whether it is a kickdown of an overdrive inhibition, and a hydraulic pressure exhaustion control device for controlling speed of exhaustion of a hydraulic pressure from the first input clutch C.sub.

Abstract: In an automatic transmission for a vehicle such as an automobile having a speed stage shifting mechanism including parallelly arranged first and second hydraulically operated input clutches and adapted to provide the 3rd speed stage in which the first and second input clutches C.sub.1 and C.sub.2 are both engaged (though the engagement of the clutch C.sub.1 in the 3rd speed stage is not essential unless engine brake availability is required) and the overdrive 4th stage in which the clutch C.sub.1 is disengaged and the clutch C.sub.2 is engaged, the clutch C.sub.1 in the 3rd speed stage being not essential unless engine a hydraulic control device has a switching over valve 330 for switching over supply of a hydraulic pressure to the first clutch C.sub.1 between a first mode of relatively slowing supplying the hydraulic pressure to the first clutch C.sub.1 and a second mode of relatively quickly supplying the hydraulic pressure to the first clutch C.sub.

Abstract: A hydraulic control device for generating a hydraulic pressure for a back pressure chamber of an accumulator in a speed stage shifting device of an automatic transmission for a vehicle such as an automobile is adapted to generate a hydraulic pressure to be supplied to the back pressure chamber of the accumulator by modulating the so-called line hydraulic pressure according to a balance between the modulated pressure itself and the line hydraulic pressure or more desirably an engine power simulation pressure modulated from the line hydraulic pressure to be lower than the line hydraulic pressure in low engine output operation under an influence of a signal hydraulic pressure controlled by an electromagnetic valve, wherein the signal hydraulic pressure decreases to substantially zero when the electromagnetic valve fails, and the accumulator control valve has a spool element having a first pressure receiving area exposed to the modulated hydraulic pressure to generate a positive feedback effect of decreasing the

Abstract: A hydraulic control device having a reverse inhibition system and applicable to an automatic transmission for a vehicle of a type including a friction engaging means for a reverse stage having a reverse exclusive hydraulic pressure chamber adapted to be supplied with a hydraulic pressure only for setting up the reverse stage, the reverse inhibition system having a reverse inhibition valve biased to a reverse inhibition position by a control hydraulic pressure for interrupting supply of hydraulic pressure to the reverse exclusive hydraulic pressure chamber and to a reverse allowance position by a hold hydraulic pressure for allowing the supply of hydraulic pressure to the reverse exclusive hydraulic pressure chamber, wherein the hydraulic pressure supplied to the reverse exclusive hydraulic pressure chamber is used for the hold hydraulic pressure.

Abstract: A hydraulic pressure control device for an automatic transmission for a vehicle, including a spool type hydraulic pressure control valve for selectively prevent setting up of the reverse stage when a manual shift valve is set to the reverse range while the vehicle is traveling forward, wherein the spool element of the hydraulic pressure control valve is positively shifted to a position for not preventing the setting up of the reverse stage by a hydraulic pressure available when the manual shift valve is set to the forward range.

Abstract: For an automatic transmission for a vehicle such as an automobile having a first friction engaging means such as a clutch which is switched over between engagement and disengagement between two adjacent speed stages such as the third speed stage and the fourth speed stage and a second friction engaging mechanism such as a brake which is engaged at two spaced apart jumping apart speed stages such as the fourth speed stage under D range and the second speed stage under S range, a hydraulic control device switches over such two friction engaging means by a first shift valve for three speed stages such as the fourth, third and second speed stages with a help of second shift valve for switching over the second speed stage and the third speed stage. A drain port of the first shift valve is supplied with a hydraulic pressure from an S port of a manual shift valve through the second shift valve.

Abstract: A hydraulic control apparatus for controlling a frictional coupling device of an automatic transmission for a motor vehicle includes a shift valve for effecting an engaging action of the coupling device from a first position to a second position, and an accumulator for reducing a change in a hydraulic pressure applied to the coupling device. The control apparatus is adapted to control a control value to regulate a back pressure of the accumulator, based on a parameter associated with an output of an engine, and according to a predetermined relationship between the control value and the parameter, so as to reduce a shifting shock of the transmission. The control apparatus includes a detector for detecting an engaging time of the engaging action of the coupling device.

Abstract: A hydraulic pressure control device for an automatic transmission for a vehicle, including a first, a second and a third hydraulic pressure control valve, wherein the third hydraulic pressure control valve cooperates with the first hydraulic pressure control valve to control switching over of a certain operation of the automatic transmission such as engagement and disengagement of a torque converter lock-up clutch during forward traveling of the vehicle, and also cooperates with the second hydraulic pressure control valve to selectively prevent setting up of the reverse stage when a manual shift valve is set to the reverse range while the vehicle is traveling forward.

Abstract: An apparatus for controlling A continuously variable transmission for use in an automotive vehicle, such that an actual engine speed coincides with a desired engine speed, wherein the desired engine speed in a transient state of the vehicle with an accelerator pedal being operated is determined based at least on a rate at which the accelerator pedal is operated.

Abstract: In a four wheel drive vehicle, wherein either a state where differential action between front wheels and rear wheels is restricted or a permitted state can be selected, the differential rate is calculated during stable running conditions, and, when the differential rate is greater than or equal to a predetermined value, the restriction of differential action is prohibited. As a result, power circulation can be prevented when there is a difference in effective radius between the front wheels and rear wheels due to, e.g., use of a temper tire, mounting of chains on the tires, or the like.

Abstract: A method wherein control of a desired engine speed occurs during a period when a throttle valve is opened at an upper limit position by an auto drive. Vo is defined as a desired vehicle speed, Vr as an actual vehicle speed, A1 as a positive constant and A2 as another positive constant smaller than A1. When Vo-Vr.gtoreq.A1, the desired engine speed is increased. When Vo-Vr<A2, the desired engine speed is decreased or maintained.

Abstract: In a continuously variable transmission (CVT), the desired engine speed is defined as a function of the throttle position. The speed ratio of the CVT is controlled such that the actual engine speed reaches the desired engine speed. The desired engine speed is set to B (Nos-Nos') upon the abrupt change in the throttle position, where B is a positive value less than 1, Nos is a desired steady-state engine speed after the change and Nos' is a desired steady-state engine speed before the change. Thereafter the desired engine speed approaches gradually the desired steady-state engine speed corresponding to the present throttle position. In the present invention the values of B in acceleration and deceleration of a vehicle are defined different from each other.

Abstract: In a four wheel drive vehicle, a central differential device receives rotational power from an engine and provides it to the combination of the front wheels of the vehicle and also to the combination of the rear wheels of the vehicle. This central differential device includes a device for selectively restricting its operation. A control device is provided for this central differential device operation restriction device, and includes: (a) a means for detecting a condition representative of the road speed of the vehicle and of the load on the engine; and (b) a means for controlling the device for selectively restricting the operation of the central differential device, so that the operation of the central differential device is less restricted than otherwise, when the vehicle speed is relatively high and also the engine output is not relatively high. Various specializations of this control device, and also the method of operation thereof, are also disclosed.

Abstract: A hydraulic control apparatus for controlling a hydraulically-operated power transmitting system for an automotive vehicle, the transmitting system having a continuously variable transmission and an auxiliary transmission coupled to an output side of the continuously variable transmission. The controlling apparatus comprises a first pressure generator for generating a first line pressure used to operate the continuously variable transmission, and a second pressure generator for generating a second line pressure used to operate a frictional coupling assembly incorporated in the auxiliary transmission.

Abstract: A hydraulic control apparatus for controlling a hydraulically hydraulically-operated power transmitting system for an automotive vehicle, the transmitting system having a continuously variable transmission and an auxiliary transmission coupled to an output side of the continuously variable transmission. The controlling apparatus comprises a first pressure generator for generating a first line pressure used to operate the continuously variable transmission, and a second pressure generator for generating a second line pressure used to operate a frictional coupling assembly incorporated in the auxiliary transmission.

Abstract: In a four wheel drive power transmission system for a vehicle, a power distribution device receives rotational power from an engine and provides rotational power to the combination of the front wheels and also to the combination of the rear wheels, and is controllable either to provide differential action between the front wheels combination and the rear wheels combination, or for this differential action to be at least partially inhibited by torque transmission. This slippage control device includes: a subsystem which estimates the torque being input to the power distribution device for four wheel drive from the transmission mechanism; and a subsystem which provides differential action inhibition of the power distribution device according to the thus estimated value of the torque being input to it from the transmission mechanism. The method of operation of this device is also described.

Abstract: A diagnostic apparatus for a continuously variable transmission the speed ratio and/or the rate of variation in the speed ratio of which are controlled by a shift-regulating device controlled by command signals from a control system.

Abstract: A continuously variable transmission (CVT) for use in a vehicle is controlled such that an actual engine speed Ne is equalized to a desired engine speed No. When a driver's request for a rapid speed change of the vehicle is addressed, a desired engine speed Ns for steady state or the desired engine speed No before the request is detected is defined as a first value Nc1. While the request continues the desired engine speed Ns for steady state which is determined by current values of vehicle running parameters is defined as a second value Nc2. The product B.multidot.(Nc2-Nc1) of a constant B and Nc2 minus Nc1 is calculated and defined as a desired engine speed during the request.

Abstract: A method and an apparatus for controlling a hydraulically-operated power transmitting system for an automotive vehicle, the power transmitting system including a continuously variable transmission and an auxiliary transmission coupled to the continuously variable transmission, the auxiliary transmission having plural speed-range positions. A shifting operation of the continuously variable transmission is restrained while the auxiliary transmission is in a shifting action.