Transmission shift control valve having fluid pressure distributor valve

A hydraulic control system for an automatic transmission which is shiftable between different gear ratios and which has a plurality of hydraulically operated frictional elements to effect shifting, the plurality of hydraulically operated frictional elements including a first, a second, and a third frictional element, the hydraulic control system comprising:

• a fluid source;
• pressure regulator valve means communicating with said fluid source for generating a line fluid pressure;
• a distributor valve including a valve body formed with a line fluid pressure inlet port and a controlled pressure port, said valve body being formed with a plurality of outlet ports communicating with the first, second, and third frictional elements, respectively, said valve body being formed with a bore serving as a drain;
• means for defining a line fluid pressure supply passage connecting said pressure regulator valve means to said line fluid pressure inlet port of said distributor valve;
• solenoid operated valve means including an inflow passage connected to said line fluid pressure supply passage via a flow restrictor, a drain port, and an output passage connected to said controlled fluid pressure port, said solenoid operated valve means being operative in a first mode where said drain port thereof is closed to allow application of said line fluid pressure to said controlled fluid pressure port, in a second mode where said drain port is fully opened to drain fluid from said controlled fluid pressure port, and in a third mode where the level of pressure applied to said controlled fluid pressure port is varied from substantially zero to the level of said line fluid pressure or from the level of said line fluid pressure to substantially zero at any desired rate with respect to time;
• said distributor valve including a valve element movably disposed within said bore of said valve body, said valve element having a plurality of positions and being movable therebetween, said plurality of positions including a first position wherein the first frictional element is connected to said output passage of said solenoid operated valve means via said first outlet port and said controlled pressure port, the second frictional element is connected to said drain via said second outlet port, and the third frictional element is connected to said drain via said third outlet port, a second position wherein the first frictional element is connected to said line fluid pressure supply passage via said first outlet port, the second frictional element is connected to said output passage of said solenoid operated valve means via said first outlet port and said controlled fluid pressure port, and the third frictional element is connected to said drain via said third outlet port, and a third position wherein the first frictional element is connected to said line fluid pressure supply passage via said first outlet port and said line fluid pressure inlet port, the second frictional element is connected to said drain via said second outlet port, and the third frictional element is connected to said output passage of said solenoid operated valve means via said third outlet port and said controlled pressure port;
• a motor operatively connected to said valve element and actuated to move said valve element to one of said plurality of positions;
• and
• control unit means for electrically controlling said solenoid operated valve means and said motor.