Cryogenic refrigerator

Claim 2

A Stirling-cycle refrigerator having a variable volume compression space, and a cold finger defining a variable volume expansion space operable at a lower average temperature than that of the compression space, comprising: an elongated, closed housing having in one end said compression space and at the opposite end the cold finger, a warm heat exchanger at the distal part of the compression space, a compression piston axially movable in the compression space adjacent and inward of the warm heat exchanger, said cold finger comprising a cylindrical part, a cold heat exchanger at the distal end thEreof, a displacer piston axially movable in the cylinder part, thus defining said variable volume expansion space with a far end adjacent the cold heat exchanger and an opposite near end, and a regenerator carried by the displacer adjacent the cold heat exchanger, drive means intermediate and engaged to the compression and displacer pistons to oscillate the pistons with a pre-selected phase difference, the drive means being a single motor with dual drive shafts extending from opposite ends, and coupling means between each of said shafts and the compression and displacer pistons respectively, and a gas duct interconnecting the warm heat exchanger and the near end of the expansion space.

Claim 3

Apparatus according to claim 1 wherein the coupling means at each motor shaft comprises a bevelled pinion gear secured axially to the shaft, a mating bevel gear rotatable about an axis normal to said shaft, an eccentric pin carried by the bevel gear and operable as a crank, and a connecting rod secured between the pin and the corresponding piston for oscillating same axially.

Claim 4

Apparatus according to claim 2 wherein at least one of said couplings means is adjustable to vary the angle of said phase difference between the two pistons.

Claim 5

A Stirling-cycle refrigerator having a variable volume compression space, and a cold finger defining a variable volume expansion space operable at a lower average temperature than that of the compression space, comprising: an elongated, closed housing having in one end said compression space, and at the opposite end the cold finger, a warm heat exchanger at the distal part of the compression space, a compression piston axially movable in the compression space adjacent and inward of the warm heat exchanger, said cold finger comprising a cylindrical part with a regenerator for receiving gas from the warm heat exchanger, a cold heat exchanger adjacent the regenerator for expansion of gas from said regenerator, and a displacer piston spaced from the compression piston and axially movable to provide said variable volume space for gas in the cold finger, drive means between the compression and displacer pistons and engaged to said pistons to oscillate them with a pre-selected phase difference, the drive means being a single motor with dual drive shafts extending from opposite ends, and coupling means between each of said shafts and the compression and displacer pistons respectively, and gas duct means interconnecting the warm heat exchanger and the expansion space.

Claim 6

A Stirling-cycle refrigerator having a variable volume compression space, and a cold finger defining a variable volume expansion space operable at a lower average temperature than that of the compression space, comprising: an elongated, closed housing having in one end said compression space, and at the opposite end the cold finger, a warm heat exchanger at the distal part of the compression space, a compression piston axially movable in the compression space adjacent and inward of the warm heat exchanger, said cold finger comprising a cylindrical part with a regenerator for receiving gas from the warm heat exchanger, a cold heat exchanger adjacent the regenerator for expansion of gas from said regenerator, and a displacer piston spaced from the compression piston and axially movable to provide said variable volume space for gas in the cold finger, drive means between the compression and displacer pistons and engaged to said pistons to oscillate them with a pre-selected phase difference, the drive means being a single motor with dual drive shafts extending from opposite ends, and coupling means between each of said shafts and the compression and displacer pistons respectively, and gas duct means interconnecting the warm heat exchanger and the expansion space.

Claim 7

Apparatus according to claim 4 wherein the regenerator is disposed at the remote end opposite the warm heat exchanger, and the cold heat exchanger is disposed intermediate the regenerator and the cold piston.

Claim 8

Apparatus according to claim 5 wherein said regenerator is fixed in place.

Claim 9

A Stirling-cycle refrigerator having a variable volume compression space, a cold finger defining a variable volume expansion space operable at a lower average temperature than that of the compression space, and a warm heat exchanger, and further comprising: an elongated, closed housing having in one end said compression space and at the opposite end said cold finger, the housing wall defining an outer surface operable as the warm heat exchanger and a compression piston axially movable in the compression space, said cold finger comprising a cylindrical part, a cold heat exchanger at the distal end of the cold finger, a displacer piston axially movable in the cylinder part, thus defining said variable volume expansion space, and a regenerator carried by the displacer, drive means intermediate and engaged to the compression and displacer pistons to oscillate the pistons with a pre-selected phase difference, the drive means being a single motor with dual drive shafts extending from opposite ends, and coupling means between each of said shafts and the compression and displacer pistons respectively, and a gas duct interconnecting the warn heat exchanger and the expansion space, this duct extending along the length of and in heat exchange relationship with the inside surface of the housing wall which is thermally conductive to said outer surface thereof.

Claim 10

A Stirling-cycle refrigerator having a variable volume compression space, a cold finger defining a variable volume expansion space operable at a lower average temperature than that of the compression space, and a warm heat exchanger, and further comprising: an elongated, closed housing having in one end said compression space and at the opposite end said cold finger, the housing wall defining an outer surface operable as the warm heat exchanger and a compression piston axially movable in the compression space, said cold finger comprising a cylindrical part, a cold heat exchanger at the distal end of the cold finger, a displacer piston axially movable in the cylinder part, thus defining said variable volume expansion space, and a regenerator carried by the displacer, drive means intermediate and engaged to the compression and displacer pistons to oscillate the pistons with a pre-selected phase difference, the drive means being a single motor with dual drive shafts extending from opposite ends, and coupling means between each of said shafts and the compression and displacer pistons respectively, and a gas duct interconnecting the warn heat exchanger and the expansion space, this duct extending along the length of and in heat exchange relationship with the inside surface of the housing wall which is thermally conductive to said outer surface thereof.

Claim 11

Apparatus according to claim 7 further comprising cooling fins extending outward from the outer surface of said housing.

Claim 12

Apparatus according to claim 8 wherein said fins extend generally radially outward and longitudinally along the length of the housing.

Claim 13

Apparatus according to claim 8 wherein the fins extend outward from the outer surface of the housing, and wind around the housing defining a curve such as a spiral or helix.

Claim 14

Apparatus according to claim 8 wherein said cooling fins are separate elements from the housing, are disposed and secured in intimate physical contact with the housing for good thermal conductivity.