Patent ID: 8171742

Claim:
A pressure wave generator configured to generate reciprocating pressure waves of operating gas for driving one or more cryogenic refrigerator systems, comprising: a housing with one or more inlet/outlet ports which the generated reciprocating pressure waves of operating gas pass through to drive a cryogenic refrigerator system or systems connected to the inlet/outlet port(s); at least one pair of opposed diaphragms located in the housing that are moveable in a reciprocating motion within the housing, each diaphragm comprising a front driving side and a rear side and wherein the diaphragms of each pair of opposed diaphragms are secured between the housing and at or toward a respective end of a reciprocating drive part such that the opposed diaphragms are operatively coupled together so that they move together; a gas space associated with each diaphragm and wherein the front driving side of each diaphragm is arranged to move in a reciprocating motion within its respective gas space to generate reciprocating pressure waves and wherein at least one of the gas spaces has an associated inlet/outlet port of the housing through which the generated pressure waves pass, the gas spaces associated with each pair of diaphragms being connected by a connection pipe comprising an orifice configured to reduce gas flow between the two gas spaces to levels that are sufficient to balance the average gas forces on the opposed diaphragms; and a drive system comprising one or more operable actuators that are arranged to drive the reciprocating drive part in a reciprocating motion to move each pair of diaphragms in a reciprocating motion back and forth in a straight path within the housing to generate the reciprocating pressure waves for driving one or more cryogenic refrigerator systems connected to the inlet/outlet port(s) of the housing, and wherein a common chamber within the housing separate to the gas spaces is defined between the rear sides of the diaphragms within which the reciprocating part(s) of the drive system move and such that the rear sides of the diaphragms move within the same common chamber, and wherein the actuator(s) of the drive system are not located in the gas spaces of the housing.