Patent ID: 6299560
Filing Date: 2001-10-09
Classification: F16H,Y10S

Abstract:
A control device for a vehicle automatic transmission having two hydraulic coupling elements belonging to a first group and two or more hydraulic coupling elements belonging to a second group and selectively establishing a plurality of shift ranges through a simultaneous engagement of said two hydraulic coupling elements of said first group and a simultaneous engagement of either one of said two hydraulic coupling elements of said first group and any one of said two or more hydraulic coupling elements of said second group, said control device comprising:shift control valves individually controlling the supply and drain of oil to and from said respective hydraulic coupling elements of said first and second groups;a fail-safe valve interposed between said shift control valves other than said shift control valves corresponding to said hydraulic coupling elements that are being intended to establish a predetermined gear change speed and an oil supply passage communicating with a hydraulic pressure source, said fail-safe valve being switchable between an open position where said oil supply passage is connected to said other shift control valves and a closed position where said connection is disconnected; anda resultant signal valve into which hydraulic pressures of said two hydraulic coupling elements of said first group are inputted, and outputting a signal pressure when the hydraulic pressures of said two hydraulic coupling elements of said first group are increased at the same time,wherein hydraulic pressures of said respective hydraulic coupling elements of said second group and said signal pressure are inputted into said fail-safe valve, and said fail-safe valve is switched over to said closed position when any two or more of said hydraulic pressures and signal pressure are increased at the same time.