Abstract: A hydraulic control system for outputting an oil pressure instruction signal to a pressure modulating mechanism, to modulate the oil pressure generated in the hydraulic pump to an oil pressure according to the instruction signal and to feed the modulated oil pressure to a transmission.

Abstract: A hydraulic control system for an automatic transmission of multiple clutch type, in which a switchover valve (2 in FIG. 4) for switching-over clutch control pressures includes two spool valvules (4 and 6). When one of two clutches (C1 and C2) is supplied with the clutch control pressure and is held in engagement, the spool valvules (4 and 6) operate to cut off the supply of the clutch control pressure for the other clutch to-be-disengaged and to hold the engagement of one clutch to-be-engaged. Thus, even when the supply source (12 or 14) of the clutch control pressure has failed, the clutches (C1 and C2) are prevented from coming into multiple engagement.

Abstract: In a hydraulic control system for an automatic transmission of multiple clutch type for use in a motor vehicle, a shift valve which inverts the supply and cutoff of working oil for a hydraulic actuator serving to change-over gear shift stages is provided with a spool valvule and a clutch-oil-pressure supply port (as shown in FIG. 1). Even when a solenoid valve for controlling the shift valve has failed, a clutch oil pressure is supplied from the clutch-oil-pressure supply port so as to hold the switchover position of the spool valvule and to keep the gear shift stage already established. Thus, the hydraulic control system prevents an engine speed from rising or the motor vehicle from locking due to the failure of the solenoid valve.

Abstract: A hydraulic control apparatus for an automatic transmission of a motor vehicle, the transmission including a lock-up clutch, the apparatus including a lock-up clutch switching valve device which is operable for selectively placing the lock-up clutch in a fully released, a partially engaged, and a fully engaged state thereof; a hydraulic pressure producing device which produces a hydraulic pressure; an abnormality detecting device which detects an abnormality of at least one of the lock-up clutch and the lock-up clutch switching valve device; and a control device which, when the abnormality detecting device detects the abnormality, operates the hydraulic pressure producing device for one of (a) applying the hydraulic pressure, and (b) inhibiting the hydraulic pressure from being applied, to at least one of the lock-up clutch and the lock-up clutch switching valve device for forcibly placing the lock-up clutch in one of the fully released and fully engaged states thereof.

Abstract: A fluid coupling has capacity coefficients in forward and reverse driving which can be arbitrarily selected to comply with demand for a wide variety of characteristics in accordance with the intended application. Pump blades Bp and/or turbine blades Bt are inclined in the direction of rotation of pump impeller P and a turbine runner T with inclination angles .theta..sub.2p and .theta..sub.2t with respect to normal lines Lp and Lt of the pump and turbine, respectively. Transfer of working fluid between the pump impeller P and the turbine runner T is thereby smoothened or suppressed in accordance with the inclination angles .theta..sub.2p and .theta..sub.2t, and thus the capacity coefficients in both forward and reverse driving can be arbitrarily selected and fixed.

Abstract: Herein disclosed is a fluid coupling which comprises: a pump impeller connected to the output shaft of an engine; and a turbine runner for transferring a working fluid to and from the pump impeller. On the pump impeller and the turbine runner, respectively, there are arranged a pump blade and a turbine blade without any inner core for guiding the flow of the working fluid inside of the pump impeller and the turbine runner. By bending at least one of the working fluid outlet side of the pump blade and the working fluid inlet side of the turbine blade, there is formed transfer limit means for limiting the transfer of the working fluid when the fluid coupling is in a stalling state.

Abstract: A hydraulic control apparatus for a vehicle power transmission for transmitting power from an engine to a drive wheel a reversing mechanism having a reverse position established by a hydraulic actuator. The apparatus includes a reverse inhibit valve disposed in a hydraulic line leading to the hydraulic actuator and having a reverse inhibit position for inhibiting the mechanism from being placed in the reverse position and a non-inhibit position for permitting the mechanism to be placed in the reverse position. The apparatus uses a first and a second pilot pressure generating device for producing a first and a second pilot pressure, respectively. A relay valve is provided for producing a first hydraulic signal for establishing the reverse inhibit position of the reverse inhibit valve, based on one of combinations of operating states of the two pilot pressure generating devices, and a second hydraulic signal for establishing the non-inhibit position, based on the other combinations.

Abstract: An apparatus for controlling a hydraulic clutch, including a two-position clutch control valve, a two-position rapid clutch release valve, and a first fluid passage system for releasing the clutch, a second fluid passage system for engaging the clutch, and a third fluid passage system for releasing the clutch. These three passage systems for feeding and discharging a fluid into and from the clutch are selected by respective three combinations of the operating positions of the two valves. Normally, a predetermined one of the first and third passage systems is selected for releasing the clutch, and the other of these two systems is selected in the event of a trouble with the valves.

Abstract: A hydraulic control apparatus for a power transmitting system for an automotive vehicle having a continuously variable transmission which has a first and a second shaft, a pair of variable-diameter pulleys provided on the first and second shafts, a belt connecting the pulleys, and a pair of hydraulic actuators for changing diameters of the pulleys, wherein a tension of the belt is controlled by regulating an actuating pressure in a driven side actuator of the hydraulic actuators which is provided on a driven one of the two shafts. The apparatus includes a pressure regulating valve which has a valve spool for regulating the actuating pressure in the driven side actuator, and a pressure-reducing chamber for receiving a pressure-reducing pilot pressure for biasing the spool for reducing the actuating pressure.

Abstract: An apparatus for controlling a vehicle continuously variable transmission, including a directional control valve having a first spool movable between a shift-down and a shift-up position, a flow control valve including a second spool movable between a flow-restricting and a non-restricting position, and a first and a second solenoid-operated valve for applying an actuating pressure to the first and second spools. The directional and flow control valves and the solenoid-operated valves are adapted such that the first and second spools are moved toward the shift-up and flow restricting positions, respectively, when the actuating pressure is not applied to the spools, or when solenoid coils of the two solenoid-operated valves are both off. The directional control valve may have a shift-down chamber for receiving a pilot pressure to move the first spool to the shift-down position when a failure of one of the solenoid coils exists while the vehicle speed is lower than a predetermined limit.

Abstract: A hydraulic control apparatus for a vehicle power transmitting system having a fluid coupling equipped with a lock-up clutch, and a transmission to which power is transmitted from an engine of the vehicle through the fluid coupling. The fluid coupling has an engaging chamber and a releasing chamber for engaging and releasing the lock-up clutch. The apparatus includes a discharge passage communicating with the engaging chamber, for normally draining the engaging chamber to a drain, to thereby normally release the lock-up clutch, and a rapid release valve connected to the discharge passage. The rapid release valve operates to by-pass the discharge passage to the drain therethrough, for thereby rapidly draining the engaging chamber to rapidly release the lock-up clutch. A lock-up pressure regulating valve is provided for regulating a lock-up clutch pressure applied to the fluid coupling, normally to a first value, and upon operation of the rapid release valve, to a second value higher than the first value.

Abstract: A hydraulic control apparatus for a vehicle power transmitting system having a continuously variable transmission having a first and a second shaft, a pair of variable-diameter pulleys provided on the shafts, a belt connecting the pulleys, and two hydraulic actuators for changing diameters of the pulleys.