Engine valve

A pressure generating device comprising in combination:

• a dome-shaped block,
• said block defining a cylinder having input and exhaust ports,
• a piston reciprocally mounted in said cylinder,
• at least one circular flat rotary valve having flat surfaces on opposite sides thereof and a port extending therethrough for controlling one of said input and exhaust ports,
• said rotary valve being mounted on said block for rotation on an outside surface thereof for controlling the associated port,
• said block defining a wear surface around the port against which said valve temporarily seats during each cycle of the pressure generating device,
• one of the flat surfaces of said valve being provided with a rack of gear teeth on that surface around its periphery at a point near its edge,
• a drive gear for meshing engagement with said rack of gear teeth,
• means for rotating said drive gear in a timed sequence for controlling the operation of said piston;
• and
• a cooling chamber formed in said block immediately below said outside surface of said block on which said valve rotates for cooling said valve,
• said cooling chamber extending over at least one-half of said outside surface of said block on which said valve rotates.