Abstract:
When the stop valve is in a first shifting position, a torque-transferring shift element is sealed tight against the rest of a hydraulic system by a stop valve, such that the actuating pressure enclosed in the shift element remains essentially constant or does not decrease. The stop valve is formed and arranged in the hydraulic system such that the stop valve is held in the first shifting position by the force of a barrier pressure generated by the pump, and, upon a standstill of the pump or falling below a certain value of the pressure generated by the pump, the stop valve is automatically displaceable at least through the action of the trapped shift element pressure into a second shifting position, in which the respective shift element is connected to the rest of the hydraulic system and the shift element is open.
Abstract:
A hydraulic pressure control device for an automatic transmission in which a single control valve selectively applies control pressure to friction elements includes a control valve and a shift valve. The control valve has a control port from which control pressure is outputted after being adjusted by a linear solenoid valve, and first and second feedback ports to which the control pressure is fed back. The shift valve is positionable in a first position when the control pressure is applied to the first friction element and a second position when the control pressure is applied to the second friction element, and is adapted to lower the control pressure outputted by the control valve in the second position of the shift valve by controlling communication of the control port with the feedback ports. In addition, an ON-OFF solenoid valve switches the position of the shift valve.
Abstract:
A transmission and control has a torque converter and clutch which is controlled between torque converter operation and torque converter clutch operation. The switch between these operations is controlled by a solenoid valve and a TCC apply valve. The solenoid valve is a normally open valve and includes a plunger that is spring loaded against a poppet valve to control the static pressure in the torque converter, during non-operating conditions of a vehicle, at or above a predetermined value.
Abstract:
Disclosed is a hydraulic control system for an automatic transmission, including a hydraulic pump; a regulator valve for constantly regulating hydraulic pressure generated from said hydraulic pump; a reducing valve for reducing hydraulic pressure regulated by the regulator valve; a first-to-second speed shift valve for feeding hydraulic pressure to a friction member which is applied as a reacting element in a second speed; and a second-to-third/fourth-to-third speed shift valve for feeding hydraulic pressure to another friction member which is applied in third and fifth speeds. The first-to-second and second-to-third/fourth-to-third speed shift valves are respectively provided with control ports to which hydraulic pressure which is used for applying a friction member in fourth and fifth speeds is fed. The control ports are connected to a line, the line being provided with a shuttle valve.
Abstract:
A control system for an automatic transmission, which receives the rotation of the engine through a fluid coupling, and which has a clutch applied when a forward running range is selected and released when a neutral range is selected and a range selecting mechanism for selecting a range. The control system includes a range detector for detecting the selected range, a hydraulic circuit and a control unit. The hydraulic circuit includes a hydraulic servo which is fed an oil pressure for applying the clutch and a manual valve movable between at least a forward range position for generating a forward range oil pressure and a neutral range position, by operation of the range selecting mechanism. A regulator valve regulates the forward range oil pressure to generate a regulated oil pressure. A solenoid valve is turned ON/OFF by the control unit to generate a signal oil pressure for switching a change-over valve between a first position feeding the forward range oil pressure to the hydraulic servo and a second position feeding the regulated oil pressure to the hydraulic servo. The control unit delays output of the signal solenoid valve, if a switching from the forward running range to the neutral range is detected by the range detector, so that the change-over valve remains in the second position until lapse of a set time period, and is then moved to a first position after the set time period has elapsed.
Abstract:
A hydraulic control for operating a five speed automatic transmission with two modulating solenoid valves. The control is particularly adapted for use with a twin countershaft automatic transmission that requires only one torque transfer device for each drive ratio. A system of valves is employed to direct the flow of the pressurized fluid necessary for the on-going actuation of each drive ratio and the simultaneously off-going deactuation of the previously actuated drive ratio. The flow control for actuating and deactuating the torque control devices is directly effected by two, two-position spool valves which operate in concert with two, two-position shuttle valves. Pressurized hydraulic fluid used to position the two-position spool valves and the two-position shuttle valves is primarily provided by two on/off solenoid control valves, but a third on/off inhibitor solenoid valve may also be employed. A failure of the electrical supply to the solenoid valves will effect a shift to the third drive ratio when the transmission is operating in the first through the fourth drive ratio, but will retain the transmission in the fifth drive ratio should the electrical failure occur while operation in that drive ratio. Similarly, the transmission will be retained in the reverse drive range should an electrical failure occur while operating in that drive range, even though the torque transfer device being utilized is also used in the forward drive range.
Abstract:
A hydraulic pressure control apparatus for an automatic transmission includes brakes and clutches to be engaged for selectively establishing gear positions in response to a controlling hydraulic pressure from a hydraulic pressure source. Two solenoid-operated valve assemblies are disposed in a hydraulic passage between the hydraulic pressure source and the brakes and clutches. The solenoid-operated valve assemblies are independently operable in response to respective control signals for controlling the supply of the controlling hydraulic pressure from the hydraulic pressure source to the brakes and clutches.
Abstract:
A control apparatus for selectively operating any one of at least three fluid pressure operated devices at any given time. The control system includes first and second valves arranged in combination with each other and which are hydraulically interposed between a fluid pressure source and each of the fluid operated devices. Each valve is shiftable between first and second positions. Hydraulic logic circuitry selectively connects the first valve to the fluid operated devices and selectively connects the second valve to the first valve whereby, for any one position of the two valves, only one of the fluid operated devices is connected to the fluid pressure source while the remainder of the fluid operated devices are open to exhaust. First and second ON/OFF solenoid operated valves facilitate positioning of the first and second valves in response to electrical signals received by the ON/OFF valves.
Abstract:
Two solenoid-actuated shuttle valves selectively direct hydraulic fluid from a line pressure source to a clutch and brake servo or direct fluid from the clutch and servo to a low pressure drain, in accordance with the combined states of the solenoids. The system includes several orifices, which in combination control the rate of flow between the pressure source and the friction elements. The orifices control also the flow rate in the system between the friction elements and drain ports. Accumulators are located in the system between the shuttle valves and the friction elements. An arrangement of check valves and orifices located between the shuttle valves and the accumulators establish the rate of flow between each of the accumulators and the associated friction element.
Abstract:
In an electronic controller for an automatic transmission having at least one driving circuit incorporating a switching device for driving a solenoid used as an actuator, at least one monitor circuit for detecting an abnormal state of the actuator, and a control section connected to these circuits, an emergency power cutoff circuit is provided between the solenoid driving circuit and the positive terminal of a battery (solenoid driving power source). The switching operation of the emergency power cutoff circuit is freely controlled to effect fail-safe control on the basis of a signal which is output from a microcomputer if, for example, the switching device in the controller malfunctions by short-circuiting.