Electro-hydraulic control with a manual selection valve

An electro-hydraulic control for a transmission having a plurality of torque transmitting mechanisms for controlling the establishment of a reverse drive ratio, a neutral condition, and a plurality of forward drive ratios, said electro-hydraulic control comprising:

• a source of pressure;
• a manual control valve selectively moveable to forward, neutral, and reverse positions;
• first, second, and third shift valves each having a solenoid valve to provide an on pressure to the respective shift valve for movement to a hydraulically on position, and each having a spring for urging the respective shift valve to a hydraulically off position when pressure from said respective solenoid valves is not present, all of said shift valves being pressurized by said respective solenoid valves during the reverse drive ratio, the neutral condition, and a first of the forward ratios;
• a first variable pressure solenoid valve communicating a first fluid pressure therefrom to said first shift valve;
• a second variable pressure solenoid valve communicating a second fluid pressure therefrom to said second shift valve;
• said variable pressure solenoid valves and said third shift valve being continuously connected with said pressure source;
• first passage means for communicating said first fluid pressure through said first shift valve to said third shift valve when said first shift valve is in said hydraulically on position;
• second passage means for connecting said first fluid pressure to said manual control valve when both of said first and third shift valves are in said hydraulically on position;
• third passage means for communicating said first fluid pressure from said manual control valve to said second shift valve to assist said spring to urge said second shift valve to said hydraulically off position regardless of the on pressure from the respective solenoid valve, said third passage means also communicating said first fluid pressure from said manual control valve to said second shift valve when said manual control valve is in said reverse position, said manual control valve communicating said third passage means to an exhaust when said manual control valve is in said neutral and forward positions;
• fourth passage means for communicating said first fluid pressure from said manual control valve to a first of said torque transmitting mechanisms when said manual control valve is in said forward position and for communicating with exhaust when said manual control valve is in said reverse and neutral positions;
• fifth passage means for communicating said first fluid pressure from said second shift valve means to a second of said torque transmitting mechanisms when said second shift valve is in said hydraulically off position and said manual control valve is in said reverse position, and for communicating said second fluid pressure from said second shift valve to said second torque transmitting mechanism when said second shift valve is in said hydraulically on position and said manual control valve is in either said neutral of forward position;
• and
• sixth passage means for communicating said second fluid pressure to a third of said torque transmitting mechanisms when said second shift valve is in said hydraulically off position.

An electro-hydraulic control for providing engagement pressure to a plurality of torque transmitting mechanisms in a power transmission to establish a plurality of forward drives, a reverse drive, and a neutral condition therein, said electro-hydraulic control comprising:

• a pressure source distributing hydraulic fluid pressure;
• a manual valve manipulable by an operator between neutral, forward, and reverse positions;
• first variable pressure valve means in continuous fluid communication with said pressure source for providing a first engagement pressure;
• second variable pressure valve means in continuous fluid communication with said pressure source for providing a second engagement pressure;
• a first shift valve having a valve spool, a control chamber connected with said spool valve and being selectively pressurized to urge said valve spool to a pressure set position, a spring chamber connected with said valve spool, and a spring disposed in said spring chamber and being in contact with said valve spool for imposing a force thereon to urge said valve spool to a spring set position, said first shift valve being in continuous communication with said first engagement pressure for distribution thereof;
• a second shift valve having a valve spool, a control chamber connected with said spool valve and being selectively pressurized to urge said valve spool to a pressure set position, a spring chamber connected with said valve spool, and a spring disposed in said spring chamber and being in contact with said valve spool for imposing a force thereon to urge said valve spool to a spring set position, said second shift valve being in continuous communication with said second engagement pressure for distribution thereof;
• a third shift valve having a valve spool, a control chamber connected with said spool valve and being selectively pressurized to urge said valve spool to a pressure set position, a spring chamber connected with said valve spool, and a spring disposed in said spring chamber and being in contact with said valve spool for imposing a force thereon to urge said valve spool to a spring set position;
• first, second, and third solenoid control valve means for selectively supplying pressurized hydraulic fluid from said pressure source to said control chambers on said first, second, and third shift valves during the reverse drive, the neutral condition, and a first of the forward drives;
• passage means for communicating said first engagement pressure from said first shift valve through said third shift valve and said manual valve to said spring chamber on said second shift valve to move said valve spool of said second shift valve to said spring set position regardless of the fluid pressure in said control chamber of said second shift valve and for communicating said first engagement pressure to a first of said torque transmitting mechanisms sequentially by way of said manual valve and second shift valve when said manual valve is in said reverse position, for distributing said first engagement pressure to a second of said torque transmitting mechanisms by way of said first shift valve, said third shift valve and said manual valve, for distributing said second engagement pressure to the first of said torque transmitting mechanisms through said second shift valve when said manual valve is in said neutral or forward position and to a third of said torque transmitting mechanisms when said manual valve is in said reverse position.