Control apparatus for automatic transmission

A control apparatus for automatic transmissions of the type having an output shaft of an engine operatively connected to an input shaft of a speed-change gear mechanism through a torque converter, and a frictional engagement device disposed in parallel to the torque converter for directly linking the output shaft to the input shaft, said control apparatus comprising means for automatically and hydraulically controlling both the selective actuation of said speed-change gear mechanism in response to the engine output and vehicle speed, and the selective actuation of said frictional engagement device for directly linking said output shaft to said input shaft in response to predetermining engine output and vehicle speed, including;

• a. governor valve means designed to be responsive to the drive speed of the vehicle for generating a governor pressure corresponding to the drive speed;
• b. throttle valve means for generating a throttle pressure in response to the opening of a throttle valve of the engine carburetor;
• c. shift valve means operatively connected to said speedchange gear mechanism and responsive to the pressures generated by said throttle valve means and said governor valve means for controlling the shifting of said speed-change gear mechanism from one gear ratio to another;
• and
• d. direct-linkage valve means operatively connected to said direct-linkage frictional engagement device and responsive to a predetermined relationship of the pressures generated by said throttle valve means and said governor means for hydraulically controlling the actuation of said direct-linkage frictional engagement device;
• and where said
• speed-change gear mechanism includes (a) speed-change frictional engagement devices hydraulically actuated by fluid pressure from said shift valve means, and (b) a speed-change planetary gear train responsive to the actuation of said speed-change frictional engagement devices for establishing different gear ratios of said speed-change gear mechanism;
• and wherein said hydraulic control means further includes (a) means individually disposed between said shift valve means and said direct-linkage frictional engagement device for reducing the fluid pressure received by selected ones of said speed-change frictional engagement devices from said shift valve means and adjusting the timing of actuation of said speed-change frictional engagement devices, (b) operation means for accepting the fluid pressure being received by said pressure-reducing means from said shift valve means and the reduced fluid pressure being received by said direct-linkage frictional engagement devices from said pressure-reducing means, and (c) interlock valve means operatively connected to said operation means and disposed between said direct-linkage frictional engagement device and direct-linkage valve means for introducing to said direct-linkage frictional engagement device the fluid pressure from said direct-linkage valve means and exhausting fluid pressure from said direct-linkage frictional engagement device in response to said fluid pressures of said operation means acting on said interlock valve means.

In automatic transmissions of the type having an output shaft of an engine operatively connected to an input shaft of a speed-change gear mechanism through a torque converter, a hydraulically actuable frictional engagement device disposed in parallel to the torque converter for directly linking the output shaft to the input shaft, a plurality of hydraulically actuable mechanisms for effecting speed changes in the speed-change gear mechanism, a source of hydraulic pressure, and valve means responsive to the engine output and vehicle speed for selectively applying the hydraulic pressure to the actuable mechanisms, apparatus for automatically controlling the hydraulically actuable, frictional engagement device comprising:

• direct linkage control means responsive to a predetermined engine output and vehicle speed for applying the hydraulic pressure to the frictional engagement device;
• means for creating a temporary hydraulic pressure differential in at least one of the hydraulic pressures being applied to the individual actuable mechanisms by the valve means for lowering the pressure applied to the individual mechanism and changing the timing of actuation of the mechanism;
• means responsive to the temporary hydraulic pressure differential for relieving the hydraulic pressure applied by the direct linkage control means to the frictional engagement means only during the continuance of the pressure differential;
• wherein the selected actuable mechanism having lowered hydraulic pressure applied thereto is for effecting relatively high speed, the means for creating a temporary pressure differential comprises a restricted orifice and an accumulator, and the means responsive to the temporary hydraulic pressure includes a floating valve element having one end sensitive to the pressure upstream of the orifice and accumulator and the other end sensitive to the pressure downstream of the orifice and accumulator, increasing pressure being applied sequentially.