Hydraulic control valve system for a planet gear transmission particularly for motor vehicles

Claim 1

In a hydraulic control valve system for a multiple-ratio, geared transmission having plural torque delivery paths extending from a driving member to a driven member, said paths being defined by planetary gear elements, clutch and brake means for controlling the relative motion of the gear elements to establish each of several torque ratios in the gearing, said clutch and brake means including a double acting intermediate speed ratio brake and a high speed ratio clutch, said brake being adapted to anchor one element of the gearing to establish a torque reaction point during an underdrive condition, said clutch being engageable selectively to establish a direct-drive, 1:1 ratio, a pressure source comprising a pump driven by said driving member, a valve circuit including a shift valve in said circuit for controlling distribution of pressure from said pump to said clutch and brake means, said brake means including a double acting servo having a piston engageable with a brake friction member, a double working chamber having a portion situated on either side of said piston, said chambers being simultaneously pressurized to establish a brake release condition, one pressure chamber being exhausted to establish a brake apply condition, and an intermediate ratio servo pressure regulator valve means in said circuit including a first passage communicating with the release side of said intermediate ratio servo and another passage communicating with a high pressure portion of said circuit, a modulator valve means for modulating the pressure in said high pressure portion to produce an accumulator pressure in said first passage, a source of a pressure signal that is proportional in magnitude to the input torque for said gearing, means for distributing said pressure signal to said servo regulator valve to control the modulating valve portions acting thereon whereby an increase in the torque related pressure establishes a decrease in the pressure in said accumulator line whereby the servo capacity for said intermediate ratio brake is proportional to the torque input.