Patent GB-819550-A (GB)
Title: Improvements in or relating to fluid pressure control valves
IPC: F16H61/00
Filed: 1957-03-11
Abstract: 819,550. Change-speed control. FORD MOTOR CO. Ltd. March 11, 1957 [April 6, 1956], No. 7898/57. Class 80 (2). A regulator valve 12, for regulating the level of steady pressure in a fluid-pressure control (not shown) of an automatic variable-ratio transmission on a motor vehicle, is associated with a pilot valve 14 which modifies the regulator characteristic under control of the usual throttle-variable, " TV," pressure to cause increase in regulated pressure in accordance with increased torque demand, and also of the usual manual drive-reverse selector 20 for pressure augmentation in reverse. Included in the system are the usual TV and kick-down valves 18, 116, loaded by the engine throttle linkage 114 to supply TV pressure to a conduit 95; a TV limit valve 16, which limits the pressure increasing effect of TV pressure on the regulator valve 12 to a maximum at 35 to 40 degrees throttle opening; and input and output driven pumps 46, 130 which supply the system through one-way valves 54, 134. Initially a pressure passage 48, fed by the input pump 46, supplies a pressure main 112 feeding the control valve circuit 112<SP>1</SP>, the TV and selector valves 18, 20 and the regulator valve 12 between lands 28, 30. In the regulator valve 12 pressure 48 passes through a restricted line 50 to act downwards on the valve plunger and through a restricted orifice 68 in the valve plunger itself, to act downwards on the pilot valve 14, depressing the latter against a spring 82 to permit a controlled flow to exhaust 78 through the valve orifice 68. The resulting flow through the orifice 68 creates a pressure differential resulting in the fluid pressure acting upwards on the regulator valve 12 and assisted by a spring 64, being less than the downward fluid pressure 50. The regulator plunger 12 is thereby depressed from its uppermost position to open the supply 48 to a restricted line 56 feeding an hydrodynamic torque converter or coupling in the transmission. Further pressure increase depresses the regulator plunger 12 further until, as shown, a land 26 opens the pump delivery 42 to suction 44, to effect final pressure regulation. In the pilot valve 14, TV pressure 95 passes through the initially depressed limit valve 16 and line 88 to act upwards on the differentially landed plunger 14, restricting the exhaust outlet 78 to increase the downward pressure differential acting on the regulator valve 12 which thus regulates to an increased. pressure. TV pressure at 88 acts upwards on the limit valve 16 through a restrictor 102, and at 35 to 40 degrees throttle opening, raises the limit valve 16 (position shown) to close the TV line 95 and exhaust excess pressure at 80, thus preventing any further increase in TV pressure from causing increase in regulated pressure. Selection of reverse at the manual valve 20 supplies reverse pressure 122 to act upwards on the pilot valve 14, augmenting regulated pressure. When output speed is high enough for the output-driven pump 130 to supply the system, the consequent pressure increase causes the regulator valve 12 to descend further and regulate output pump pressure between lands 28, 36, whilst increasing the exhaust passage of the input pump 46 between lands 26, 34 to unload that pump.