Patent ID: 8632433
Filing Date: 2014-01-21
Classification: F16H,Y10T

Abstract:
1. A hydraulic control system for an automatic transmission having a first friction engagement element to be engaged at establishment of a first forward gear and establishment of a reverse gear, and a second friction engagement element to be engaged at least at establishment of a second forward gear different from the first forward gear, the system comprising: a range pressure output unit that outputs a reverse range pressure when a reverse range is selected; a first switching valve having a reverse range pressure input port to which the reverse range pressure is input, a control pressure input port to which a control pressure from a linear solenoid valve is input, a first output port, a second output port, and a third output port connected to a hydraulic servo of the second friction engagement element, and switched to a first state in which the reverse range pressure input port and the second output port, the control pressure input port and the third output port are communicated with each other and a second state in which the reverse range pressure input port and the first output port, the control pressure input port and the second output port are communicated with each other; a second switching valve having a first input port connected to the first output port, a second input port connected to the second output port, and a fourth output port connected to a hydraulic servo of the first friction engagement element, and switched to a third state in which the second input port and the fourth output port are communicated with each other and a fourth state in which the first input port and the fourth output port are communicated with each other; a first on/off solenoid valve that may output a signal pressure for switching the first switching valve; and a second on/off solenoid valve that may output a signal pressure for switching the second switching valve.