Control valve system for a continuously variable belt driven transmission for motor vehicles

A hydraulic valve system for controlling a continuously variable drive ratio automotive vehicle transmission adapted to shift continuously between different drive ratios and having first and second control pulleys driveably connected by an endless traction belt, a displacement cylinder associated with each pulley, the location of the belt on each pulley being radially variable in response to hydraulic fluid pressure in the associated cylinder to shift between the drive ratios, comprising:

• first and second hydraulic fluid pumps;
• main pressure regulation valve means connected to the discharge of the second pump for producing line pressure and torque converter supply pressure;
• torque converter means for hydrodynamically, driveably connecting the engine of the vehicle to a transmission pulley, said torque converter means having an impeller, a turbine, the impeller connected to the engine, the turbine connected to said pulley;
• a lockup clutch adapted to selectively driveably connect the turbine and the impeller when hydraulic fluid flows in a first direction through the torque converter and to disconnect the turbine and impeller when said flow is in the opposite direction;
• a lockup valve supplied with line pressure, coupled to the electronic control means for opening and closing communication between line pressure and a converter lockup pressure line in accordance with the control of the electronic control means;
• a lockup on-off valve subject to torque converter lockup pressure for connecting torque converter supply pressure to the inlet of the torque converter and for connecting line pressure to the outlet of the torque converter in accordance with the control of the torque converter lockup pressure;
• torque converter relief valve means supplied with torque converter discharge pressure and line pressure for producing emergency control pressure at an outlet port when the discharge flow rate from the torque converter is above a predetermined flow rate and for disconnecting line pressure from the outlet port when said flow rate is below the predetermined flow rate;
• ratio control valve means hydraulically connected to the discharge of the first pump for selectively opening hydraulic communication between the discharge of the first pump and the first and second displacement cylinders to produce ratio control pressure;
• and
• an emergency shift valve means subject to emergency control pressure and ratio control pressure supplied with torque converter discharge pressure for connecting the ratio control valve means to the converter discharge pressure when emergency control pressure and ratio control pressure are absent.