Thermodynamic reciprocating machine

Claim 2

A thermodynamic reciprocating machine including a cylinder, a reciprocable displacer located in the cylinder, a gas inlet through the cylinder wall, a gas outlet through the cylinder wall, valve means located between the cylinder wall and the displacer and operated by the displacer to open and to close the inlet and the outlet, an expansion chamber which includes the space defined by one end of the displacer and the cylinder, and which is able to receive gas entering the inlet and to expel gas through the outlet, and a regenerator for exchanging heat between gas entering and leaving the expansion chamber, in which machine the displacer is reciprocated by a varying differential pressure between the gas in the expansion chamber and a restoring pressure.

Claim 3

A thermodynamic reciprocatinG machine according to claim 1, in which the restoring pressure is exerted by a gas in a driving chamber which includes the space defined by the ends of the displacer and the cylinder opposite to the ends thereof defining the expansion chamber, in which the driving chamber has a pressure-relief device set to exhaust gas at a pressure between the maximum and minimum pressures that are created in the expansion chamber by the reciprocating displacer, in which the driving chamber is divided into first and second compartments, the first compartment being in part bounded by the end of the displacer, in which passage of gas from one compartment to the other is permitted by a one-way valve when the pressure in said one compartment is greater than in said other compartment, and in which passage of gas from said other compartment to said one compartment is through a constriction between the compartments when the pressure in said other compartment is greater than in said one compartment.

Claim 4

A thermodynamic reciprocating machine according to claim 2, in which the one-way valve permits gas flow only from the first compartment to the second compartment.

Claim 5

A thermodynamic reciprocating machine according to claim 1, in which a restricted passage leads to the driving chamber from a passage leading to the inlet of the expansion chamber.

Claim 6

A thermodynamic reciprocating machine according to claim 1, in which two sealing rings are located between the displacer and the inner surface of the cylinder wall, one sealing ring being located on one side of the inlet and outlet of the expansion chamber, the other sealing ring being located on the other side of the inlet and the outlet.

Claim 7

A thermodynamic reciprocating machine, according to claim 1, in which the valve member includes at least one ring in frictional engagement with the inner surface of the cylinder wall, in which the ring is located between the end walls of a recess formed in the displacer.

Claim 8

A thermodynamic reciprocating machine, according to claim 6, in which the end face of the ring nearer to the expansion chamber is able to make a seal with the end wall of the recess facing said end face, whereby for the greater part of the period when the displacer is moving to increase the volume of the expansion chamber, the valve ring directly closes the inlet to the expansion chamber and makes the said seal to close the outlet to the expansion chamber.

Claim 9

A thermodynamic reciprocating machine according to claim 6, in which there is a valve member for the inlet provided by a ring in frictional engagement with the inner surface of the cylinder wall and located between the walls of a first recess in the displacer, in which there is a valve member for the outlet provided by a ring in frictional engagement with the inner surface of the cylinder wall and located between the walls of a second recess in the displacer wall, in which both rings are operated by being contacted and displaced by the end walls of the recesses in which they are located, and in which the difference in length between the outlet ring and the recess in which it is located is greater than the difference in length between the inlet ring and the recess in which it is located, whereby both the inlet and the outlet are able to be closed for the greater part of the period during which the displacer is moving to increase the volume of the expansion chamber.

Claim 10

A thermodynamic reciprocating machine according to claim 1, in which the region of the cylinder wherein the inlet and outlet of the expansion chamber are located is of smaller cross-sectional area than the region of the cylinder that bounds the driving chamber.

Claim 11

A thermodynamic reciprocating machine according to claim 1, and further including more than one regenerative stage.

Claim 12

A thermodynamic reciprocating machine according to claim 1, in which at least part of the region of the cylinder that, in part, bounds the expansion chamber is made of a heat-conductive material to facilitate heat transfer beTween a load being cooled and the gas in the expansion chamber.

Claim 13

A thermodynamic reciprocating machine including a cylinder, a reciprocable displacer located within the cylinder, an expansion chamber which includes the space defined by one end of the displacer and the cylinder, a driving chamber which includes the space defined by the other end of the displacer and the cylinder, an inlet through the cylinder wall leading from the expansion chamber, an outlet through the cylinder wall leading from the expansion chamber, a regenerator located between the inlet and outlet and the expansion chamber for exchanging heat between gas entering and leaving the expansion chamber, and at least one valve member which is in frictional engagement with the inner wall of the cylinder, and which is located between the walls of a recess in the displacer, said at least one valve member being operated by the displacer to open and to close the inlet and the outlet, in which machine the displacer is caused to reciprocate by a varying differential pressure exerted against the displacer by the gas in the expansion chamber and the gas in the driving chamber.

Claim 14

A thermodynamic reciprocating machine including a cylinder, a reciprocable displacer located within the cylinder, an expansion chamber which includes the space defined by one end of the displacer and the cylinder, a driving chamber which includes the space defined by the other end of the displacer and the cylinder, an inlet through the cylinder wall leading from the expansion chamber, an outlet through the cylinder wall leading from the expansion chamber, a regenerator located between the inlet and outlet and the expansion chamber for exchanging heat between gas entering and leaving the expansion chamber, and at least one valve member which is in frictional engagement with the inner wall of the cylinder, and which is located between the walls of a recess in the displacer, said at least one valve member being operated by the displacer to open and to close the inlet and the outlet, in which machine the displacer is caused to reciprocate by a varying differential pressure exerted against the displacer by the gas in the expansion chamber and the gas in the driving chamber.

Claim 15

The thermodynamic machine defined by claim 6 in which a single ring is employed and the length of said ring measured along the axis of the cylinder is greater than the distance between the inlet and outlet measured along the same axis.