Hydraulic control device for an automatic transmission

Claim 1

In an automatic transmission of an automobile having a mechanical planetary gearing system with hydraulically actuatable gearshift elements for selective engagement of transmission elements; a manual control valve having positions depending upon the position of a manually actuatable selector lever, said manual control valve conveying pressurized fluid for actuation of said gearshift element when said selector lever is positioned for a forward gear, and a pressure medium line communicating between said manual control valve and said gearshift element; a hydraulic control device comprising: a shift valve means arranged in said pressure medium line for selectively interrupting the delivery of said pressurized fluid, said shift valve means comprising a piston, said piston controlling the delivery of said pressurized fluid to said gearshift element and being acted upon in one direction by a return spring and acted upon in an opposite direction by a pressure depending upon the position of an accelerator pedal; a fluid line for delivering pressurized fluid to said piston, for imparting said pressure depending upon the position of an accelerator pedal, said fluid line being connected through a throttle point with a pressure line carrying an engine load-dependent pressure; and a control valve means, arranged in said fluid line and actuatable by said accelerator pedal, for venting said fluid line when said accelerator pedal is released, and for connecting said fluid line directly with said pressure line, for bypassing said throttle point, when said accelerator pedal is actuated beyond a predefined position.