GB1371115A - Control valve circuit for a vehicle automatic transmission - Google Patents

Abstract

1371115 Change-speed control FORD MOTOR CO Ltd 30 Oct 1972 [2 Nov 1971] 49915/72 Heading F2D To compensate for the reduction in eng ne intake depression without the usual correspond ing increase in torque caused by operating a motor-vehicle engine with exhaust gas recirculation (EGR) to reduce exhaust emissions, in an automatic transmission having fluid-pressure engaged ratio-establishing friction clutches and brakes selected by automatic shiftvalves responding to opposing output-speed responsive governor pressure and throttle (TV) pressure 114, a primary TV valve 130, loaded rightwards by engine intake depression acting on a spring-loaded diaphragm 148, is provided with additional rightward loading by a spring 170, such additional loading being normally neutralized by line pressure acting leftwards on a differential land 160 of a secondary piston 128, and supplied through a line 164 which is exhausted by a solenoid valve 166 when EGR is in operation, thus reducing TV pressure. The transmission (Fig. 1, not shown) is the conventional torque-converter-driven Simpson planetary gear set providing two reduced ratios, direct drive and one reverse, and the control circuit (Fig. 2, not shown), also conventional, includes 1-2 and 2-3 automatic shift valves, a manual RND21 valve, a main pressure regulator valve loaded by TV pressure subject to a cutback valve responding to governor and TV pressure to reduce line pressure at higher speeds, and a TV boost valve for processing the TV pressure applied to the shift valves. TV pressure is also increased during reverse operation, to augment line pressure, by supplying line pressure at 142 to act leftwards on a differential land of the primary TV valve 130.