US3638441A — Device for producing cold at low temperatures

Claim 1

Independent Claim 422 words

A device for producing cold at low temperatures comprising at least one cold-gas refrigerator having at least one compression space of a variable volume and a higher average temperature, as well as at least two expansion spaces of likewise variable volume and lower average temperature than that of the compression space, said spaces communicating with each other and a regenerator being present in each of the communications, the volume of the said expansion spaces being variable by a pistonlike body which is constructed from parts having different diameters, an outlet valve being arranged in the wall of the final expansion space having the lowest average temperature during operation, said valve opening when the pressure in said space is higher than the minimum pressure and preferably is substantially equal to the maximum pressure which occurs in the cold-gas refrigerator, a duct communicating with said valve which duct communicates via the high-pressure side of one or more heat exchangers with an expansion device in which the working medium expands, said medium being in heat exchange relationship with a place to be cooled, from which place the working medium flows back, via the lowpressure side of the said heat exchangers and a compression device to an inlet valve which communicates with one of the said spaces of the cold-gas refrigerator, characterized in that the compression device is formed by a cylinder incorporated in the pistonlike body which can vary the volume of the expansion spaces, in which cylinder a hollow further pistonlike body which is rigidly secured to the wall of one of the expansion spaces and move in such manner that the centerline of the cylinder-piston combination coincides with or is parallel to the centerline of the relative pistonlike body, the further pistonlike body communicating, on its side connected to the wall, with the duct through which low-pressure medium flows from the expansion device to the cold-gas refrigerator and comprising on its other side a suction valve through which working medium can flow into the cylinder, the cylinder on its side facing the interior of the pistonlike body being closed by a plate in which a pressure valve is provided which opens when the pressure in the cylinder exceeds the minimum pressure which occurs in the said expansion and compression spaces, said valve opening into a buffer space which, via a nonreturn valve, communicates with an intermediate expansion space having a higher average temperature than that prevailing in the final expansion space, said nonreturn valve opening in the direction of said intermediate expansion space.

Claim 2

Independent Claim 422 words

A device for producing cold at low temperatures comprising at least one cold-gas refrigerator having at least one compression space of a variable volume and a higher average temperature, as well as at least two expansion spaces of likewise variable volume and lower average temperature than that of the compression space, said spaces communicating with each other and a regenerator being present in each of the communications, the volume of the said expansion spaces being variable by a pistonlike body which is constructed from parts having different diameters, an outlet valve being arranged in the wall of the final expansion space having the lowest average temperature during operation, said valve opening when the pressure in said space is higher than the minimum pressure and preferably is substantially equal to the maximum pressure which occurs in the cold-gas refrigerator, a duct communicating with said valve which duct communicates via the high-pressure side of one or more heat exchangers with an expansion device in which the working medium expands, said medium being in heat exchange relationship with a place to be cooled, from which place the working medium flows back, via the lowpressure side of the said heat exchangers and a compression device to an inlet valve which communicates with one of the said spaces of the cold-gas refrigerator, characterized in that the compression device is formed by a cylinder incorporated in the pistonlike body which can vary the volume of the expansion spaces, in which cylinder a hollow further pistonlike body which is rigidly secured to the wall of one of the expansion spaces and move in such manner that the centerline of the cylinder-piston combination coincides with or is parallel to the centerline of the relative pistonlike body, the further pistonlike body communicating, on its side connected to the wall, with the duct through which low-pressure medium flows from the expansion device to the cold-gas refrigerator and comprising on its other side a suction valve through which working medium can flow into the cylinder, the cylinder on its side facing the interior of the pistonlike body being closed by a plate in which a pressure valve is provided which opens when the pressure in the cylinder exceeds the minimum pressure which occurs in the said expansion and compression spaces, said valve opening into a buffer space which, via a nonreturn valve, communicates with an intermediate expansion space having a higher average temperature than that prevailing in the final expansion space, said nonreturn valve opening in the direction of said intermediate expansion space.

Claim 3

Dependent Claim 168 words

A device as claimed in claim 1, characterized in that the cold-gas refrigerator comprises more than two expansion spaces and the further pistonlike body is constructed from a number of parts which, viewed from the connection of said body to the wall of the cold-gas refrigerator, show a decreasing diameter and in which each of the annular surfaces constituted by the transition of two adjacent parts influence the volume of a compression space, the various compression spaces being arranged in series through ducts having incorporated therein buffer spaces, if desirable, the inlet of the first compression space communicating with the low-pressure side of the said heat exchanger and the outlet of the last compression space communicating, via an outlet valve and a buffer space, if desirable, with an inlet valve which opens into the intermediate expansion space which is situated nearest to the compression space, each of the ducts between two successive compression spaces being in heat exchange relationshIp with the medium in an associated intermediate expansion space.

Claim 4

Dependent Claim 140 words

In a cold-gas refrigerating apparatus, including a displacer movable within a housing and defining therein at least one variable-volume expansion space in which working medium is expanded to a first pressure and temperature, this apparatus operable with a further expansion device wherein the medium is further expanded to a second temperature and pressure lower than said first temperature and pressure, the improvement in combination therewith of means for compressing said further expanded medium comprising a compression chamber defined as a bore within said displacer, a piston fixed to said housing and extending into said chamber which chamber moves relative to the piston when the displacer moves, first duct means communicating the further expanded medium from the further expansion device into said compression space, and second duct means communicating the medium from the compression chamber to one of said expansion spaces.

Claim 5

Dependent Claim 140 words

In a cold-gas refrigerating apparatus, including a displacer movable within a housing and defining therein at least one variable-volume expansion space in which working medium is expanded to a first pressure and temperature, this apparatus operable with a further expansion device wherein the medium is further expanded to a second temperature and pressure lower than said first temperature and pressure, the improvement in combination therewith of means for compressing said further expanded medium comprising a compression chamber defined as a bore within said displacer, a piston fixed to said housing and extending into said chamber which chamber moves relative to the piston when the displacer moves, first duct means communicating the further expanded medium from the further expansion device into said compression space, and second duct means communicating the medium from the compression chamber to one of said expansion spaces.

Claim 6

Dependent Claim 57 words

Apparatus according to claim 3 further comprising a one-way outlet valve for permitting medium flow from said expansion space to said further expansion device, a one-way suction valve for permitting medium flow from said further expansion device to said compression chamber, and another one-way valve for permitting medium flow from the compression chamber to said expansion space.

Claim 7

Dependent Claim 41 words

Apparatus according to claim 3 wherein said compression chamber comprises a first part into which said piston extends, and a second part buffer space, and a one-way valve permitting medium flow from said first to said second part of said chamber.

Claim 8

Dependent Claim 41 words

Apparatus according to claim 4 wherein said compression chamber comprises a first part into which said piston extends, and a second part buffer space, and a one-way valve permitting medium flow from said first to said second part of said chamber.

Claim 9

Dependent Claim 196 words

In a cold-gas refrigerating apparatus, including a displacer movable within a housing and defining therein at least one variable-volume expansion space in which working medium is expanded to a first pressure and temperature, this apparatus operable with a further expansion device wherein the medium is further expanded to temperature and pressure lower than said first temperature and pressure, the improvement in combination therewith of means for compressing said further expanded medium to be returned to said expansion space for recycling, comprising a compression chamber formed as a bore within said displacer, the bore defining a compression space and a buffer space, and a one-way valve which separates and permits flow only from the compression space into the buffer space, a duct communicating the buffer space to said expansion space with a one-way valve therebetween permitting flow only from the buffer space into the expansion space, a hollow piston secured to the housing and extending into said compression space for compressing medium therein when the displacer moves relative to the fixed piston, a one-way valve in said piston for permitting flow of further expanded medium only from the expansion device through the piston into the compression space.

Claim 10

Dependent Claim 196 words

In a cold-gas refrigerating apparatus, including a displacer movable within a housing and defining therein at least one variable-volume expansion space in which working medium is expanded to a first pressure and temperature, this apparatus operable with a further expansion device wherein the medium is further expanded to temperature and pressure lower than said first temperature and pressure, the improvement in combination therewith of means for compressing said further expanded medium to be returned to said expansion space for recycling, comprising a compression chamber formed as a bore within said displacer, the bore defining a compression space and a buffer space, and a one-way valve which separates and permits flow only from the compression space into the buffer space, a duct communicating the buffer space to said expansion space with a one-way valve therebetween permitting flow only from the buffer space into the expansion space, a hollow piston secured to the housing and extending into said compression space for compressing medium therein when the displacer moves relative to the fixed piston, a one-way valve in said piston for permitting flow of further expanded medium only from the expansion device through the piston into the compression space.

Claim 11

Dependent Claim 85 words

Apparatus according to claim 5 having at least two expansion spaces one of higher temperature and pressure than the other, and wherein said compression chamber''s first part and second buffer part define a first portion, and the chamber comprises a second portion similar to and axially spaced from the first portion, said piston has two portions corresponding to the first and second portions of the compression chamber, and the buffer space of said second portion communicates with said expansion space of higher temperature and pressure.

Claim 12

Dependent Claim 27 words

Apparatus according to claim 8 further comprising heat exchange means between the first compression chamber and an expansion space having lower temperature than said first compression space.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-01-31	1975-08-02	1976-02-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-01-31	1979-08-02	1980-02-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-01-31	1983-08-02	1984-02-01	$7700.00	Window Closed / Lapsed

Device for producing cold at low temperatures

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag