A hydraulic control device that includes a primary pressure control valve that has a first valve element and that regulates the primary pressure by varying a position of the first valve element in accordance with operation of a first electromagnetic actuator; a secondary pressure control valve that has a second valve element and that regulates the secondary pressure by varying a position of the second valve element in accordance with operation of a second electromagnetic actuator; and a fail-safe valve that varies the position of the first valve element such that the primary pressure is reduced when the first electromagnetic actuator and the second electromagnetic actuator become inoperable.

A hydraulic control apparatus including a first and second control valves switched to exert hydraulic pressure on a piston to press toward first position, a third and fourth control valves switched to exert hydraulic pressure on the piston to press toward second position and, a CPU. The CPU performs executing a first process controlling the control valves so that hydraulic pressure is exerted by switching of the first, second and third control valves or a second process controlling the control valves so that hydraulic pressure is exerted by switching of the second control valve and determining that the first control valve is failed when movement of the piston to the first position is not detected through the first process and determining that the third control valve is failed when movement of the piston to the first position is not detected through the second process.

Ground wires are shared between a drive-side pulley solenoid valve and a driven-side pulley solenoid valve. Therefore, when a disconnection or short circuit occurs in the shared portion, a drive-side pulley and a driven-side pulley show substantially the same behavior. As a result, changes in the speed ratio γcvt of a continuously variable transmission are suppressed and changes in vehicle behavior are also suppressed. Therefore, it is possible to suppress the degradation of drivability during the failure of the solenoid valves involved in power transmission.

An automatic transmission where the control portion controls the adjustment solenoid valve so that the circulation hydraulic pressure equals to a second circulation hydraulic pressure higher than the first circulation hydraulic pressure when the rotational speed difference between the output rotational speed of the fluid transmission device and the rotational speed of the driving source is more than the predetermined rotational speed.

A hydraulic pressure control device of a vehicle driving device, the hydraulic pressure control device includes a range switcher having a first signal solenoid valve capable of supplying a first signal pressure and a spool switchable between a first position reached via the first signal pressure and a second position reached via a biasing force of a biasing member.

A hydraulic control device that includes a normally closed first solenoid valve, a first check valve, a failsafe valve, and a second check valve, wherein the first movable member of the first check valve is biased to cut off the communication between the first input port and the first drain port in case of the failure in which no current is applied to the first solenoid valve.

A control apparatus for a vehicular continuously variable transmission is provided. The control apparatus includes a pair of pulley pressure adjusting valves, a pair of electromagnetic valves, a source pressure adjusting valve and an electronic control unit. The electronic control unit is configured to control the source pressure adjusting valve in such a manner as to lower the source pressure at a time of a fail mode below the source pressure at a time of a non-fail mode, at the time of the fail mode, and control command signals to the pair of the electromagnetic valves such that the command signals temporarily decrease below command signals at the time of the non-fail mode, before cancelling the lowering of the source pressure in making a changeover from the fail mode to the non-fail mode.

A drive apparatus for a hybrid vehicle includes: (a) a hybrid drive unit having (a-1) an automatic transmission, (a-2) a first rotating machine and (a-3) an engine connected to the first rotating machine through a hydraulically-operated connecting/disconnecting device; (b) an electric drive unit including a second rotating machine; and (c) a hybrid control device configured, in event of an anomaly that disables a shift control of the automatic transmission, to generate an electric power by causing the first rotating machine to be rotated by the engine and drive the hybrid vehicle to run by causing the second rotating machine of the electric drive unit to be operated with use of the generated electric power, in a state in which a power transmission through the automatic transmission is cut off and the connecting/disconnecting device is engaged.

A vehicle power transmission device includes: a continuously variable transmission including a primary pulley, a secondary pulley, and a transmission belt wound between the primary pulley and the secondary pulley; a belt running clutch of hydraulic type for transmitting power to the continuously variable transmission; and a hydraulic control circuit controlling the continuously variable transmission and the belt running clutch. The hydraulic control circuit includes a fail-safe valve switching a communication destination of an oil supply passage for supplying a hydraulic fluid to the belt running clutch to one of a first oil passage supplied with a control hydraulic pressure and a second oil passage supplied with a hydraulic pressure higher than the control hydraulic pressure, the fail-safe valve connecting the oil supply passage with the second oil passage when the fail-safe valve is switched to a failure position. The second oil passage is provided with an orifice.

A drive apparatus of a hybrid vehicle including an internal combustion engine, a first motor-generator, a power division mechanism, a second motor-generator and a mode switching unit. The mode switching unit includes a hydraulic pressure source, a planetary gear mechanism, a clutch actuator, a brake actuator, a parking lock actuator, control valves, a failure detecting part and an electronic control unit, A microprocessor of the electronic control unit is configured to perform controlling the control valves so that hydraulic oil is supplied to the clutch actuator, the brake actuator and the parking lock actuator, respectively, when a parking brake is operated in a state that the failure of the third control valve is detected by the failure detecting part.