Pressure equalization system for a stirling engine

A working gas control system for a double acting type Stirling cycle engine 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 variations from a minimum cycle pressure to a maximum cycle pressure during operation of the engine, each of the piston assemblies connected with a connecting rod, and each having a rod seal assembly for sealing the connecting rod, the control system comprising:

• the rod seal assemblies having an internal cavity,
• a first volume defined by hollow interiors of the pistons communicating through a first passageway in the connecting rods to the rod seal assembly internal cavities and with a second passageway,
• a check valve connected with each of the cycle volumes and the first volume, the check valves permitting flow from the first volume to the cycle volumes when the gas pressure of the cycle volume is less than the gas pressure of the first volume minus a lift-off pressure of the check valve, the check valves inhibiting working gas flow from the first volume to the cycle volumes, the check valves causing the gas pressure in the first volume to be maintained near the minimum cycle pressure during operation of the engine,
• a second volume configured to remain near a mean cycle pressure between the minimum and the maximum cycle pressures of all cycle volumes separated by the two or more piston assemblies during operation of the engine, the second volume having a constant volume, a respective permanent first restrictor connecting each of the cycle volumes with the second volume, and
• a respective second restrictor connecting the first volume with each of the cycle volumes, whereby, during operation of the engine, working gas flows between the cycle volumes by flowing through the first and second restrictors.

A method of controlling a working gas for a double acting type Stirling cycle engine 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 during operation of the engine, each of the piston assemblies connected with a connecting rod, and having a rod seal assembly for sealing the connecting rod, the control system comprising:

• forming a first volume defined by hollow interiors of the pistons communicating together through a first passageway in the connecting rods to a second passageway, the first volume configured to be near the minimum cycle pressure during operation of the engine, and
• providing a check valve connecting the cycle volumes with the first volume, whereby, during operation of the engine, the working gas flows from the first volume to the cycle volumes to maintain the pressure in the first volume near the minimum level,
• forming a second volume configured to remain near a mean cycle pressure between the minimum and the maximum cycle pressures of all cycle volumes separated by the two or more piston assemblies during operation of the engine by communicating with each of the cycle volumes via a respective third passageway having a permanent first restrictor, the second volume having a constant volume, wherein, during operation of the engine, the working gas of the cycle volumes is exchanged between the cycle volumes to provide control of the volume of working gas in the cycle volumes.