Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
  • F25B9/02—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using Joule-Thompson effect; using vortex effect
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
  • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
  • F25J1/005—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by expansion of a gaseous refrigerant stream with extraction of work
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
  • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
  • F25J1/0052—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant stream
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
  • F25J1/007—Primary atmospheric gases, mixtures thereof
  • F25J1/0077—Argon
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
  • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
  • F25J1/0275—Construction and layout of liquefaction equipments, e.g. valves, machines adapted for special use of the liquefaction unit, e.g. portable or transportable devices
  • F25J1/0276—Laboratory or other miniature devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2270/00—Refrigeration techniques used
  • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
  • F25J2270/912—Liquefaction cycle of a low-boiling (feed) gas in a cryocooler, i.e. in a closed-loop refrigerator

Definitions

• This invention relates generally to low temperature refrigeration systems, and more particularly to closed cycle cryogenic cooling systems and apparatus.
• Cooling apparatus and systems capable of producing very low (cryogenic) temperatures find applications in many different fields, such as in electronics.
• electronic or electro-optical devices such as infrared, x-ray and gamma ray detectors, solid state lasers, and low noise amplifiers, requires that the devices be cooled to cryogenic temperatures.
• devices and their associated cooling systems must often operate under remote or adverse environmental conditions, such as aboard spacecraft, aircraft or other vehicles, wherein space and weight are at a premium and where high reliability and long operating life are required.
• open cycle cooling systems commonly have been employed.
• One such open cycle cooling system stores refrigerant gas under high pressure in a pressure vessel.
• J-T Joule-Thomson
• the liquid refrigerant is puddled to cool the device.
• Cold refrigerant vapor is then routed back through the heat exchanger to cool the incoming gas and is then vented out of the system.
• the pressure vessel used for storing the refrigerant must be removed, refilled, and returned to the system quite frequently.
• the invention affords miniature closed cycle cooling apparatus that avoid the foregoing disadvantages and that satisfy the above-stated requirements.
• Systems in accordance with the invention are rugged and lightweight, possess exceptionally high reliability and efficiency, and are capable of operating for long periods of time in remote or adverse environments.
• the systems have a rather simple construction and have low input power requirements. They are capable of operating over a wide cryogenic temperature range between approximately 4.2°K and 100°K (-268.8°C and -173°C) with any of a number of common refrigerants such, as helium, neon, nitrogen, argon or methane, without modification, are capable of very rapid cool down from high ambient temperatures, and are capable of maintaining very accurately a preselected cryogenic temperature.
• the systems may be constructed to have a size of the order of 4 inches (10 cm. ) in diameter by 5 inches (13 cm.) in length, or smaller, and a weight of the order of 4-1/2 to 6 pounds (2 to 2-3/4 kg.), making them ideal for use aboard spacecraft or aircraft.
• the invention provides cooling apparatus that comprises compressor means for compressing a gas and for providing a compressed gas output, expander means for enabling the expansion of a portion of the compressed gas and for enabling the expansion of the compressed gas to perform work, and fluid means connecting the compressor means and the expander means for applying the work produced by the expansion of the gas to the compressor means to assist the compressor means in compressing the gas.
• the invention affords cooling apparatus that comprises diaphragm compressor means for compressing a gas, first expander means for receiving a first portion of compressed gas from the compressor means and for enabling expansion of the gas and for enabling the expansion of the gas to perform work, means for applying the work of expansion to the compressor means to assist the compressor means in compressing the gas, second expander means for receiving a second portion of compressed gas from the compressor means and for expanding the gas to liquefy a part thereof, and means for returning the expanded gas to the compressor means for recompression.
• the invention affords cooling apparatus comprising compressor means for compressing a gas, expander means comprising a movable member disposed within an expansion chamber for enabling expansion of the gas and for enabling the expansion of the gas to perform work, the expansion chamber having an inlet valve and an outlet valve for respectively admitting and discharging gas and the valves being arranged so as to be operated by the movable member, and means for applying said work to the compressor means.
• the invention affords an integral electrically-actuated fluid-operated compressor and expander apparatus that enables the work of expansion of a precooled pressurized refrigerant gas to be returned to the compressor so as to reduce the power input required to compress gas.
• the compressor/expander is constructed so as to avoid sliding seals or rubbing parts that may contribute to refrigerant contamination, and employs novel Inlet and outlet valve arrangements. The manner in which this is accomplished will be described more fully hereinafter. Brief Description of the Drawings
• Fig. 1 is a block diagram illustrating schematically a closed cycle cooling system in accordance with the invention
• Fig. 2- is a schematic diagram illustrating the system of Fig. 1 in somewhat greater detail
• Fig. 3 is a temperature-entropy (T-S) diagram of the thermodynamic cycle of the system of Fig. 2 employing argon as a refrigerant;
• Fig. 4 * is a longitudinal cross-sectional view taken along the line 4-4 of Fig. 5 of compressor/expander apparatus in accordance with the invention;
• Fig. 5 is an end elevational view of the compressor/ expander apparatus of Fig. 4; .
• Fig. 6 is a transverse sectional view taken along the line 6-6 of Fig. 4;
• Figs. 7-A and 7B are fragmentary sectional view taken along the lines 7A-7A and 7B-7B of Figs. 5 and 6, respectively;
• Fig. 8 is an enlarged fragmentary sectional view similar to Fig. 4, but taken from a different angle, of a portion of the compressor/expander apparatus;
• Fig. 9 is a sectional view taken along the line 9-9 of Fig. 8;
• Figs. 10A and 10B are, respectively, enlarged fragmentary plan and sectional views of portions of Figs. 8 and 9 illustrating a preferred outlet valve arrangement;
• Figs. 11A and 11B are, respectively, enlarged fragmentary sectional and plan views of portions of Figs. 8 and 9 illustrating a preferred inlet valve arrangement
• Fig. 1-2 is an enlarged fragmentary sectional view of a preferred inlet and outlet valve arrangement of the expander portion of the compressor/expander apparatus of Fig. 4. Description of the Preferred Embodiment
• the invention is primarily intended for use on vehicles, where minimum size and weight are very important, to provide cryogenic cooling to an electronic or electro-optical device, 5 and it will be described in that context. However, this is illustrative of only one utility of the invention and, as will become apparent, the invention is well suited for other purposes.
• Fig. 1 illustrates schematically a closed cycle
• the system comprises a dual-stage compressor 22, an expander 24, first and second reversing heat exchangers 26 and 28, respectively, and a pressurized container or dewar 30.
• a cryostat comprising
• a device 36 to be cooled may be placed in the bottom of the dewar, and may have appropriate input and output connections 38 and 40 thereto through the wall of the dewar.
• Low pressure (LP) refrigerant gas preferably argon, for example, enters the first stage of the compressor at 50 where it is compressed to a predetermined medium pressure (MP) .
• MP medium pressure
• a portion Cfor example 75%) of the pressurized gas from the first stage is tapped off at 52
• the precooled high pressure gas is further cooled in heat exchanger 32 (by returning cold vapor) and undergoes expansion and liquefaction at the output of J-T valve 34.
• the liquid refrigerant within the dewar is at a cryogenic temperature and serves to cool device 36.
• Cold vapor returned from the dewar through heat exchanger 32 is joined at 54 with the expanded cold gas from expander 24 and is returned to the low pressure side of the compressor through heat exchangers 26 and 28, where it cools the medium pressure and high pressure gas flowing therethrough.
• Cooling system 20 is based upon a modified Claude cycle system which is widely used in the gas liquefaction industry for liquefying air and other gases.
• Industrial systems employ large rather complicated rotary turbine- ype compressors and expanders, mechanically coupled together, which do not lend themselves to miniaturization. Moreover, these systems do not possess the requisite characteristics necessary for unattended operation under remote or adverse environmental conditions .
• the invention affords a system which has a rather simple construction, which is capable of being miniaturized, and which is capable of a rather high figure of merit, defined as the ratio of the theoretical minimum work requirement to the actual work requirement of the system, of the order of 0.378.
• Fig. 2 illustrates the closed cycle cooling system of the invention in more detail.
• the heart of the system is a compressor/expander 60 which, as will ' be described in more detail hereinafter, preferably comprises an integral, electrically-actuated fluid-operated two-stage diaphragm compressor 22 and piston expander 24.
• Fig. 3 is a temperature-entropy (T-S) diagram illustrating the thermo ⁇ dynamic cycle of the system for an ambient temperature of 343°K (100°C). Temperatures, pressures and mass flow rates at various points in the system are indicated by the encircled lower case letters in Figs. 2 and 3. As will become apparent, however, the system may employ other refrigerant gases and may be readily designed for other operating parameters .
• low pressure refrigerant gas enters the first stage 62 of the compressor from low-pressure, e.g., 0-3 psi CO-21 kg/m ), accumulator 64 via an inlet check valve VI.
• the first stage compresses the gas to a
• Heat exchangers 26 and 28 may be the first and second stages, respectively, of a reversing heat exchanger 70.
• Heat exchanger 70 may also be a tapped heat exchanger having first and second portions 26 and 28, and may be of conventional construction.
• the second stage of the compressor compresses the gas entering valve V3 to a high
• the compressed gas exits the second stage via an outlet check valve V4 and is routed to a high pressure (.875 psi) 2 (6,157 kg/m ) accumulator 72. From the high pressure accumulator, the compressed gas is then routed through both the first and second stages 26 and 28 of heat exchanger 70 and to the cryostat 58 via the inner line 74 of a coaxial bidirectional transfer line 76. In the cryostat, the high pressure gas passes through J-T expansion valve 34 where it undergoes expansion and liquefaction in the dewar
• Cold vapor from the dewar is returned to the system via an outer return line 78 of coaxial transfer line 76 that surrounds inner line 74.
• the returning cold vapor is fed through a back pressure regulator valve V9 to the return inlet 80 of the second stage 28 of heat exchanger 70.
• the gas is allowed to expand and to do work, thereby lowering its temperature.
• the expanded cold gas exits the expander via an outlet valve V6 and is joined with the returning cold vapor — from the dewar at the return inlet 80 of the second stage of the heat exchanger.
• the returning cold vapor from the dewar and the cold gas from the expander flow through the heat exchanger, they absorb heat from the high pressure gas flowing to the cryostat and from the medium pressure gas flowing to the expander, thus cooling and purifying these gases.
• the system may also include a fill valve V7 to enable the system to be charged with refrigerant (preferably through a filter 84) , and may include a cut-off valve V8 connected to a junction 86 in the high pressure line from accumulator 72 and adapted for connection to a pressure gauge 88.
• Accumulators 64, 66 and 72 constitute surge tanks for reducing pressure surges in the system. As is shown schmetically in Fig.
• each stage of the compressor 22 of compressor/expander 60 comprises a cavity 90 communicating with the inlet and outlet valves of the compressor stage.
• a displaceable resilient diaphragm member 92 is disposed within each cavity and is arranged such that one side of the diaphragm constitutes one wall of the cavity.
• the opposite side of the diaphragm communicates with a reservoir 94 containing a fluid, which may be either a gas or a liquid.
• a preferred liquid is fluorosilicon oil.
• the fluid reservoir of each stage may be in communication with an oil (.or other fluid) accumulator 96 via respective by-pass orifice check valves V10 and Vll, as shown, to enable the reservoirs to be maintained full of oil.
• Each reservoir is preferably formed as a resilient bellows 98 connected at one end to ' a movable member 100, a portion of which constitutes the armature of a solenoid 102.
• the solenoid which may comprise a magnetic core 104 and a coil 106, is adapted to be energized by a pulsed DC voltage on electrical conductors 108.
• member 100 is moved to the left (in Figure 2) decreasing the volumes of the reservoirs 94 and causing the oil to apply pressure to diaphragms 92 to displace the diaphragms to the left. This reduces the volume of the cavities and compresses the gas within the cavities.
• a portion of member 100 constitutes a piston 110 which is disposed within an expansion chamber 112 of expander 24.
• inlet valve V5 of the expander opens (in a manner which
• the solenoid is actuated by a rectangular 0 wave DC voltage at approximately a 50 Hz rate, for example.
• the DC voltage causes member 100 to undergo reciprocating motion, producing compression and discharge of pressurized gas from the cavities and allowing expansion of gas in expansion chamber 112 as the member moves to the left, and 5 permitting a new charge of gas to enter the cavities while discharging expanded gas from the expander as the member moves back to the right.
• the duty cycle of the rectangular wave DC voltage may be varied so as to vary the compression stroke, and the voltage on-time may be selected so that 0 the voltage turns off just prior to the desired end of the stroke in order to take advantage of the momentum of the movable member to complete the stroke.
• the system may also include a pressure regulator switch 120 connected in series with electrical conductors 108 that supply power to the solenoid.
• the switch monitors the pressure in the inlet line of accumulator 72 and opens and closes to control actuation of the solenoid to maintain the
• cryostat 58 comprises a J-T valve 34 located on the end of a tubular member 32 (which corresponds to heat exchanger 32 of Fig. 1).
• the cryostat is disposed within pressurized dewar- 30 and may be connected to the inner line 74 of transfer line 76 by a connector 122, for example.
• the transfer line may comprise a flexible inner line 74, as of stainless steel, surrounded y an outer flexible bellows, as of electro-deposited nickel, that forms return line 78.
• the transfer line may also be covered with insulation (not illustrated) and should be kept short (e.g., 24 inches ' (61 cm.) or less) in order to minimize the heat loss therefrom.
• the gas expansion within expander 24 is a thermodynamically reversible process and, therefore, is more efficient than the gas expansion through the J-T valve 34, which is an irreversible process.
• the solenoid work per unit of gas liquefied is reduced and higher efficiency is obtained.
• the temperature of the gas entering the expander at point is 222°K (-51°C) .
• the gas temperature at f is 118°K (-155°C .
• O PI expander 24 effects substantial precooling of the high pressure gas flowing through the heat exchanger such that the temperature of the high pressure gas is lowered from 377°K (104°C) at the inlet b, £ of the heat exchanger to 139° (-134°C) at its outlet g, and such that after expansion from the J-T valve 34, the temperature is 88°K (-185°C) (j_, k) , assuming a 24-inch coaxial transfer line 76 between the system and the cryostat.
• the system of Fig. 2 is capable of providing cool down from an ambient temperature of approximately 160°F (71°C) to a temperature of less than 100°K (-173°C) in approximately 3-1/4.minutes with only 50 watts of power required for the cool down phase, and of sustaining a one-quarter watt cooling capacity of liquid argon temperature with only 10 watts of power.
• the liquid temperature of the refrigerant in the dewar is a function of the internal pressure of the dewar, and the liquid temperature can be very accurately controlled by controlling the internal pressure.
• Back pressure regulator valve V9 enables the internal pressure within the dewar to be maintained at a preselected value so as to accurately maintain a desired liquid temperature. This also affords very good temperature stability.
• FIGs. 4-12 illustrate in more detail a preferred form of an integral compressor/expander 60 in accordance with the invention.
• compressor/ expander 60 may have a generally cylindrical multi-part housing comprising a cup-shaped solenoid housing 130, a compressor plate 132, a cylindrical housing extension 134 and an expander housing 136.
• the parts may be all formed of aluminum, for example, and may be held together by a plurality of bolts 138 and 140, as shown in Figs. 5-7B.
• Solenoid housing 130 may be formed with a plurality of radially directed heat-dissipating fins 142 which extend substantially about the circumference thereof.
• the magnetic core 104 of the solenoid may be secured to an end plate 144 of the solenoid housing, as by a screw 146, as shown.
• An electrical connector 148 adapted for connection to electrical conductors 108 may extend through end plate 144 to enable power to be supplied to solenoid coil 106, which may be disposed within an annular slot in the magnetic core as shown.
• a solenoid armature 150 is disposed within the solenoid housing between the magnetic core 104 and the end wall 152 of the solenoid housing. Upon the solenoid being energized, the armature moves to the left in Fig. 4 and may engage the magnetic core. The armature stroke may be of the order of 0.060 inch. Ci-5 mm.).
• the first stage of the compressor comprises a- lenticular-shaped cavity 160 formed between the oppositely contoured walls of a pair of insert members 162 and 164 positioned within mating cut-outs formed in end wall 152 of the solenoid housing and in compressor plate 132.
• a dish-shaped resilient diaphragm 166 as of beryllium-copper alloy or stainless steel, may be disposed within the cavity and sandwiched between insert members 162 and 164, and is preferably shaped to conform to the wall surface of insert 164 within the cavity, as shown.
• Insert member 162 may include an inlet valve VI in communication with the cavity and with a gas inlet passageway 170 formed in end wall 152 of the solenoid housing and an inlet line 172 from accumulator 64 (Fig. 2) and may also include a plurality of outlet valves V2 in communication with the cavity and with a gas outlet passageway 174* (see Fig. 8). (The valves will be described in more detail shortly) .
• insert member 164 may have a plurality of holes 180 therethrough that connect an oil (or other fluid) plenum 182 formed in compressor plate 132 to the right side (in the figures) of the diaphragm. The holes are preferably arranged to distribute oil pressure substantially uniformly to the diaphragm.
• the oil plenum is, in turn, connected to an oil reservoir 184 (to be described more fully shortly) via a plurality of oil passageways 186 through the compressor plate.
• the second stage of the compressor may have the same construction as the first stage, except that it may be smaller since it is required to handle a smaller flow rate (257_ of the flow rate of the first compressor stage, for example), and may comprise a lenticular-shaped cavity 190 formed between insert members 192 and 194 positioned within mating cut-outs in compressor plate 132 and a cover plate 195.
• a dish-shaped resilient diaphragm 196 which may also be of a beryllium-copper alloy or stainless steel, is disposed within the cavity and secured between insert members 192 and 194.
• Insert member 192 may include an inlet and outlet valve arrangement similar to that of the first stage, the inlet valve V3 connecting the cavity to a gas inlet passageway 198 and inlet line 200 (from accumulator 66) , and the outlet valve arrangement V4 connecting the cavity to a gas outlet passageway in the cover plate and an outlet line 202 (shown in Figs . 5 and 6) .
• Insert member 194 may likewise have a plurality of holes 204 therethrough connecting the cavity to an oil plenum 206 in cover plate 195 that, in turn, communicates with an oil reservoir 208 via an oil passageway 210 in the cover plate.
• a piston member 220 disposed within the cylindrical housing extension 134 and the expander housing 136 is a piston member 220 comprising a tubular U-shaped (in cross- section) center portion 222 with a closed end 224, a centrally located radially directed circular flange 226 extending outwardly from the center portion, and a circular end plate 228 topped by a piston plate 230 connected to end ' 224 of the center portion, as shown.
• Flange 226 may have a diameter that is slightly less 5 than the inner diameter of the cylindrical housing extension 134 and is preferably located on center portion 222 of the piston member so as to abut the end wall 232 of the expander housing within the cylindrical housing extension as piston plate 230
• End plate 228 and piston plate 230 constitute an expander piston 238 that is disposed within a cylindrical
• the end plate and piston plate may have a diameter slightly less than the inner diameter of the chamber.
• a resilient bellows 242 is connected at one end to end plate 228 and at the other end to the expander housing adjacent to wall 0 232. This provides a seal between expansion chamber 240 and the cylindrical housing extension 134, and avoids the necessity for sliding seals on the piston.
• Another resilient bellows 244 having one end sealingly connected to flange 226 of the piston member and one end sealingly 5 connected to an annular flange 246 of compressor plate 132 defines the oil reservoir 184 for the first stage of the compressor.
• a resilient bellows 248 disposed within the tubular center portion 222 of the piston member and connected to piston plate 195 defines oil 0 reservoir 208 for the second stage of the compressor.
• the oil reservoirs may be connected to oil accumulator 96 (see Fig. 2) via oil passageways (not illustrated) formed in compressor plates 132 and 195.
• Bellows 242, 244 and 248 are preferably metallic and may be
• Flange 226 of piston member 220 may be connected to solenoid armature 150 by a plurality of bolts 260 that extend through bushings 262 in compressor plate 132 and end wall 152 of the solenoid housing, as shown in Figs. 4 and 6, and are threaded into the solenoid armature.
• Bolts 260 serve as guide pins (in cooperation with bushings 262) and constrain the piston member for movement with the solenoid armature.
• the positions of the solenoid armature and piston member shown in Fig. 4 correspond to the solenoid being unenergized. When the solenoid is energized, the solenoid armature and piston member are moved to the left in the figure to the positions shown in phantom lines.
• the inlet and outlet valves V5 and V6 of the expander may be disposed in wall 234 of the expander housing (see Fig. 12) to enable them to be controlled by the expander piston 238.
• the inlet and outlet valves ' are, respectively, in communication with inlet and outlet lines 270 and 272 (see Figures 5 also) that connect the exapnder to heat exchanger 70.
• Fig. 8 illustrates the first stage of the compressor in somewhat more detail than Fig. 4 (and also from a different angle than Fig. 4).
• gas inlet passageway 170 is in communication with a centrally located recess 280 in insert member 162 and with compressor cavity 160 via a hole 282 that extends through the insert member between recess 280 and the
• OMPI contoured surface 284 of the insert member that constitutes the left (in Figs. 8 and 11A) wall of the cavity.
• a leaf spring 286 may be disposed within a mating depression or seat 288 formed in wall 284 and located so that one end of the leaf spring covers hole 282.
• the other end of the leaf spring may be connected, as by welding, to a threaded member 289 that extends through insert member 162 and is secured thereto with a nut 290 and a washer 292.
• the leaf spring constitutes a reed valve. When it flexes to the phantom line position shown in Fig. 11A, it uncovers hole 282 and allows gas to enter the* cavity.
• Leaf spring 286 is preferably selected to have a spring constant such that the inlet valve opens at an inlet line pressure slightly less than the desired inlet pressure, e.g., at approximately 2.5 psi (17.6 kg/m ) .
• the second stage inlet valve V3 may likewise have a leaf
• Figs. 8-10B illustrate a preferred outlet valve V2 arrangement which, as will be described, preferably comprises a plurality of ball valves.
• insert member 162 may be formed with an annular recess 300 that is in communication with gas outlet line 174 in end wall 152 of the solenoid housing.
• a plurality of stepped-diameter holes 302 may extend through the insert member between annular recess 300 and cavity 160. Each hole serves as a valve seat for a small ball 304, as of stainless steel, that is disposed therein.
• Each ball may be biased into engagement with the small diameter portion 306 of the hole (corresponding to the closed position of the valve) by a radially inwardly directed resilient finger 308 of a generally annular-shaped leaf spring member 310 that is sandwiched between insert member 162 and an annular retaining ring 312.
• the inner diameter edge 314 of the retaining ring serves to limit the travel of the resilient fingers 308 (to the phantom line position illustrated) to prevent the balls 304 from slipping out of holes 302 when the valves open.
• the outlet valves are normally held closed by the resilient fingers of the leaf spring, and they are all adapted to open at approximately the same time to allow gas in the cavity to be discharged into annular recess 300 and gas outlet passageway 174, in a,manner which, will be described shortly.
• leaf springs individual compression springs for the balls may also be used.
• both the inlet and outlet valves may be of the same type, such as reed valves, ball valves or other types of valves.
• the outlet valves are arranged in a circle about the inlet valve, other arrangements may be employed.
• the outlet valves may be located close to the center of insert member 62 and one or more inlet valves may be disposed about the outlet valves. The reason for employing a plurality of outlet valves is to ensure the complete discharge of compressed gas from the cavity. As previously indicated, the gas within the cavity is compressed during the first part of the diaphragm stroke and is discharged from the cavity during the latter part of the stroke.
• the first stage has a compression ratio of the order of 10:1.
• the gas within the cavity is compressed during approximately 90% of the diaphragm stroke and is discharged during only the last 107_ of the stroke.
• the plurality of outlet valves enables complete discharge of the compressed gas from the cavity during the relatively small discharge portion of the stroke.
• a single inlet valve VI is sufficient since gas can be supplied to the cavity during the entire return (intake) stroke of the diaphragm.
• seals 320 such as gaskets or O-rings, may be employed for sealing inlet cavity 282 and annular outlet cavity 300.
• seals 322 may be employed between insert member 164 and compressor plate 132 for sealing oil plenum 182.
• Fig. 12 illustrates a preferred arrangement for inlet valve V5 and outlet valve V6 of the expander.
• the inlet valve may comprise a leaf spring 324 disposed within a cavity 326 that is in communication with inlet line 270 (see Fig. 5) .
• One end of the leaf spring is sandwiched between an insert member 328 and a retaining plate.330 disposed within wall 234 of the expander housing adjacent to expansion chamber 240.
• a rigid projection 332 connected to the leaf spring extends through an opening 334 in the retaining plate and into the chamber.
• the leaf spring is sized to cover opening 334 and is normally biased into engagement with the retaining plate so as to close the opening between cavity 326 and- expansion chamber 240. This Is the normally closed position of inlet valve V5.
• Outlet valve V6 may similarly comprise a leaf spring 340 disposed between insert member 328 and retaining plate 330 and normally biased to uncover an opening 342 in the insert member that is in communication with a cavity 334 and outlet line 272. This is the normally open position of outlet valve V6.
• Leaf spring 340 may be formed with a resilient arcuate projection 346 that extends into expansion chamber 240, as shown.
• Gaskets 348 may be disposed between retaining plate 330 and insert member 328 and between insert member 328 and the expander housing, as shown, for sealing purposes.
• Inlet valve V5 is normally closed and outlet valve V6 is normally open as noted above.
• expander piston 238 is at the ends of its expansion stroke, and expansion chamber 240 has its maximum volume.
• piston plate 230 engages projection 346 of leaf spring 340 to move the leaf spring to the phantom line position corresponding to the closed.position of the outlet valve.
• leaf spring 324 returns to the solid line position to close the inlet valve, which is held closed because of the gas pressure in the inlet line.
• the outlet valve remains in closed position because of the pressure of the gas within the expansion chamber.
• Inlet valves VI and V3 are held closed during the compression stroke by the gas pressure in the cavities.
• the outlet valves V2 and V4 are held closed, as previously indicated, because of the gas pressures in the outlet lines.
• the outlet valves open and the pressurized gas is discharged from the cavities during the last portion of the compression stroke.
• the gas in the expansion chamber 240 acts against piston 238 and does work by aiding the solenoid in moving piston member 220 to the left.
• the power to the solenoid is turned off.
• Solenoid armature 150, piston member 220 and expander piston 238 thereafter move back to the right in the figure because of the resiliency of the bellows and the force against the piston member produced by gas entering the cavities through inlet valves VI and V3 that acts against the diaphragms to return the diaphragms to their original positions.
• the expanded gas is discharged from the expansion chamber, as previously described.
• the expander piston reaches the top of its stroke, a new charge of gas is taken into the expander and power is reapplied to the solenoid to repeat the cycle.
• the compressor/ expander does not require close tolerances nor sliding seals which can deteriorate and cause contamination of the refrigerant.
• the compressor can be hermetically sealed.
• the construction of the compressor/expander also enables it to be made quite small and lightweight, and its simplicity affords high reliability.
• the fluid coupling between the expander and the compressor avoids the high fatigue and stress that is typically associated with mechanical (rigid) couplings, such as gears or levers, and the fluid coupling minimizes the pressure differentials .that are applied to opposite sides of the diaphragms. This
• OMPI minimizes stress and fatigue and affords a long diaphragm life.
• the fluid coupling is also convenient for efficiently dissipating the heat of compression and con ⁇ tributes to a more efficient operation.
• 5 the fluid need not be incompressible. In some appli ⁇ cations, a compressible fluid might be desirable for damping purposes.
• the compressor/expander may be readily miniaturized, and a cooling system in accordance with the invention 10 capable of providing flow rates and temperatures such as those given in connection with the discussion of Figs. 2 and 3 may have dimensions of the order of 4 inches (10 cm.) in diameter by 5 inches (13 cm.) in length and a weight of the order of 4-1/2 to 6 pounds (2 to 2-3/4 kg), 15. as noted above.
• cooling systems in accordance with the invention may also be larger and may be configured to accommodate different flow rates and different temperatures. They may also use another gas as a refrigerant, although argon is preferred, and may be 0 easily adapted to employ other than electrical driving mechanisms.

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• Engineering & Computer Science (AREA)
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• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Clinical Laboratory Science (AREA)
• Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
• Compressor (AREA)

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• 1984
  • 1984-01-31 EP EP19840901244 patent/EP0136342A4/en not_active Withdrawn
  • 1984-01-31 WO PCT/US1984/000142 patent/WO1984003139A1/en not_active Application Discontinuation
  • 1984-01-31 JP JP59501194A patent/JPS60500424A/ja active Pending
  • 1984-01-31 AU AU26959/84A patent/AU2695984A/en not_active Abandoned
  • 1984-02-07 IL IL70886A patent/IL70886A0/xx unknown
  • 1984-02-09 IT IT8447668A patent/IT8447668A0/it unknown

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