Piston assembly for stirling engine

A piston assembly for reciprocation within a cylinder bore of a double-acting hot gas engine including a double-acting Stirling engine, said piston assembly comprising:

• a piston rod,
• a piston head, attached to said piston rod, forming an annular clearance space and having a radially outer-most surface,
• a sealing washer, positioned within said annular clearance space, having first and second opposed flat faces and radially inner-most and outer-most surfaces,
• first and second closed sealing rings,
• said first sealing ring positioned between said sealing washer and said piston head, said first sealing ring, said sealing washer and said piston head forming a first actuating cavity, said first sealing ring positioned in a sealing relationship with said first opposed flat face of said sealing washer, said first sealing ring and said piston head forming a first ring passageway allowing working fluid to be exchanged between said first actuating cavity and said cylinder bore, and
• said second sealing ring positioned between said sealing washer and said piston head, said second sealing ring, said sealing washer and said piston head forming a second actuating cavity, said second sealing ring positioned in a sealing relationship with said second opposed flat face of said sealing washer, said second sealing ring and said piston head forming a second ring passageway allowing working fluid to be exchanged between said second actuating cavity and said cylinder bore.

A piston assembly for reciprocation within a cylinder bore of a double-acting hot gas engine including a double-acting Stirling engine, said piston assembly comprising:

• a piston rod,
• a piston head attached to said piston rod, having an interior cavity and forming an annular sealing ring groove, said annular sealing ring groove having walls and a radially inner-most surface,
• a sealing ring, formed of elastic low friction material, located within said annular sealing ring groove, having radially inner-most and outer-most surfaces, separated from said radially inner-most surface of said annular sealing ring groove by an actuating cavity, said actuating cavity connected to said interior cavity by a cavity passageway,
• two gaskets, located on opposing sides of said sealing ring within said annular sealing ring groove, said gaskets contacting said walls of said annular sealing ring groove and said sealing ring and substantially inhibiting the passage of working fluid into or out of said actuating cavity between said sealing ring and said walls of said annular sealing ring groove, and
• pressurization means for positively pressurizing said actuating cavity, thereby causing said radially outer-most surface of said sealing ring to be urged into constant sealing engagement with said cylinder bore of said engine.

A piston assembly for reciprocation within a cylinder bore of a double-acting engine including a double-acting Stirling engine, said piston assembly comprising:

• a piston rod,
• a piston head, connected to said piston rod, forming an annular sealing ring groove, said annular sealing ring groove having a radially inner-most surface,
• a sealing ring, formed of elastic low friction material, located within said annular sealing ring groove, having radially inner-most and outer-most surfaces, said radially inner-most surface of said sealing ring separated from said radially inner-most surface of said annular sealing ring groove by an actuating cavity, and
• actuating cavity pressurization means for positively pressurizing said actuating cavity, thereby causing said radially outer-most surface of said sealing ring to be constantly urged into sealing engagement with said cylinder bore of said engine.