Abstract: An automatic transmission system includes a transmission having transmission elements with lubrication-requiring portions and hydraulic actuators therefor, a switching valve that supplies hydraulic fluid to the hydraulic actuators, a valve actuator that actuates the switching valve, a shift range detection unit that detects a selected shift range of the transmission, and a control unit that controls the valve actuator to actuate the switching valve in accordance with the selected transmission shift range. The switching valve has a bypass position to provide a supply of the hydraulic fluid to the lubrication-requiring portions by bypassing a transmission oil cooler. The control unit judges whether the transmission is in a low lubrication state based on a given operating parameter of the transmission and controls the valve actuator to switch the switching valve to the bypass position at the time the transmission is judged as being in the low lubrication state.

Abstract: An automatic transmissions control system varies times to start a shift to securing a good response in engagement pressure for an engagement-side frictional element as well as suppressing occurrence of hydraulic pressure vibrations at low temperatures.

Abstract: An automatic transmission system includes a transmission having transmission elements with lubrication-requiring portions and hydraulic actuators therefor, a switching valve that supplies hydraulic fluid to the hydraulic actuators, a valve actuator that actuates the switching valve, a shift range detection unit that detects a selected shift range of the transmission, and a control unit that controls the valve actuator to actuate the switching valve in accordance with the selected transmission shift range. The switching valve has a bypass position to provide a supply of the hydraulic fluid to the lubrication-requiring portions by bypassing a transmission oil cooler. The control unit judges whether the transmission is in a low lubrication state based on a given operating parameter of the transmission and controls the valve actuator to switch the switching valve to the bypass position at the time the transmission is judged as being in the low lubrication state.

Abstract: An automatic transmissions control system varies times to start a shift to securing a good response in engagement pressure for an engagement-side frictional element as well as suppressing occurrence of hydraulic pressure vibrations at low temperatures.

Abstract: A hydraulic control device for an automatic transmission comprises an engagement element pressure control section for controlling an engagement element pressure, engagement elements supplied with the engagement element pressure, and an oil pressure switches provided in oil supply paths of the engagement element pressure. The plural gear positions are achieved by engaging or disengaging the engagement elements. The engagement element pressure control section controls the engagement element pressure with a first gain when the engagement elements are in the shifting state and controls the engagement element pressure with a second gain when the engagement elements are in the engagement state.

Abstract: A hydraulic control device for an automatic transmission comprises an engagement element pressure control section for controlling an engagement element pressure, engagement elements supplied with the engagement element pressure, and an oil pressure switches provided in oil supply paths of the engagement element pressure. The plural gear positions are achieved by engaging or disengaging the engagement elements. The engagement element pressure control section controls the engagement element pressure with a first gain when the engagement elements are in the shifting state and controls the engagement element pressure with a second gain when the engagement elements are in the engagement state.

Abstract: A second shift valve for a lock-up clutch is switched in response to supply of an R range pressure and a solenoid pressure from a low-and-reverse solenoid valve to selectively supply an output from a lock-up solenoid valve to a pressure reduction control valve or a lock-up control valve. The pressure reduction control valve regulates a line pressure at a small gain by the output from the lockup solenoid valve via the second shift valve. The first shift valve actuated by the solenoid pressure from the low-and-reverse solenoid valve selectively supplies a high R range pressure from a manual valve or an output from the pressure reduction control valve to the low-and-reverse brake. This enables accurate hydraulic control of the low-and-reverse brake and ensures the required torque capacity with simple arrangement.

Abstract: A second shift valve for a lock-up clutch is switched in response to supply of an R range pressure and a solenoid pressure from a low-and-reverse solenoid valve to selectively supply an output from a lock-up solenoid valve to a pressure reduction control valve or a lock-up control valve. The pressure reduction control valve regulates a line pressure at a small gain by the output from the lockup solenoid valve via the second shift valve. The first shift valve actuated by the solenoid pressure from the low-and-reverse solenoid valve selectively supplies a high R range pressure from a manual valve or an output from the pressure reduction control valve to the low-and-reverse brake. This enables accurate hydraulic control of the low-and-reverse brake and ensures the required torque capacity with simple arrangement.

Abstract: In a control device of an automatic transmission that controls a plurality of solenoid valves by an ATCU to thereby supply and release signal pressure for controlling friction elements according to selected gear positions, the solenoid valves generate a signal pressure to be supplied to the friction elements which are engaged at a predetermined gear position in a low speed gear position group, when the ATCU stops functioning while the vehicle is driven at a low speed gear position. Shift valves supply the signal pressure to the friction elements. If the ATCU stops functioning while a gear position in a high speed gear position group is selected, the shift valves supply a signal pressure generated by manual valve to friction elements which are engaged at a predetermined gear position in the high speed gear position group.