Control valve for a stirling engine

A control valve for a double acting type Stirling cycle engine of the type having two or more piston assemblies reciprocating within cylinder bores, each of the piston assemblies separating isolated cycle volumes of a working gas contained within the engine, the cycle volumes undergoing cyclical pressure changes from a minimum cycle pressure to a maximum cycle pressure, each of the piston assemblies connected with a connecting rod, and having a rod seal assembly for sealing the connecting rod, the engine having a valve port for receiving the control valve which communicates with the cycle volumes and with a pressure volume, the control valve comprising:

• a valve body forming a first passageway for communicating with the cycle volume,
• a valve plug having a hollow interior passage forming a second passageway for communicating with the pressure volume,
• a plunger moveable between a closed position against a seat which seals against the seat and an open position displaced from the seat, wherein, in the closed position, flow between the cycle volume and the pressure volume is restricted and in the open position the flow between the cycle volume and the first volume is enabled,
• a spring urging the plunger to the closed position such that the plunger moves to the open position when the pressure in the first passageway is less than the pressure in the second passageway by more than a predetermined pressure difference, and
• an actuator acting on the plunger to move the plunger to the open position against the urging force of the spring to thereby connect the passageways.

A double acting type Stirling cycle engine comprising:

• two or more piston assemblies reciprocating within cylinder bores, each of the piston assemblies separating isolated cycle volumes of a working gas contained within the engine, the cycle volumes undergoing cyclical pressure changes from a minimum cycle pressure to a maximum cycle pressure,
• the engine having block forming a valve port for each of the cycle volumes which each communicate with one of the cycle volumes and with a pressure volume, and
• a control valve disposed in each of the valve ports and forming a first passageway for communicating with the cycle volume and a second passageway for communicating with the pressure volume, the control valve further having a plunger moveable between a closed position against a seat which seals against the seat and an open position displaced from the seat, wherein, in the closed position, flow between the first passageway and the second passageway is restricted and in the open position the flow between the passageways is enabled, a spring urging the plunger to the closed position such that the plunger moves to the open position when the pressure in the first passageway is less than the pressure in the second passageway by more than a predetermined pressure difference, an actuator acting on the plunger to move the plunger to the open position against the urging force of the spring to thereby connect the passageways.