US2803951A

US2803951A - Refrigerating compressor

Info

Publication number: US2803951A
Application number: US554990A
Authority: US
Inventors: Alwin B Newton
Original assignee: Coleman Co Inc
Current assignee: Coleman Co Inc
Priority date: 1955-12-23
Filing date: 1955-12-23
Publication date: 1957-08-27
Anticipated expiration: 1974-08-27

Description

Aug. 27, 1957 A. BVNEWTON 2,803,951

' REFRIGERATING COMPRESSOR Filed D90. 23, 1955 2 Sheets-Sheet l ATTORNE Y5 Aug. 27, 1957 Filed D90. 23. 1955 A. B. NEWTON 2,803,951

REFRIGERATING COMPRESSOR 2 Sheets-Sheet 2 INVENTOR.

United States Patent REFRIGERATIN G COMPRESSOR Alwin B. Newton, Wichita, Kans., assignor to The Coieman Company, Inc., Wichita, Kans, a corporation of Kansas Application December 23, 1%5, Serial No. 554,999

16 Claims. (Cl. 62-115) This invention relates to a compressor structure adapted for use in a refrigeration system. More particularly, the invention relates to a combined heat and externally powered compressor wherein the energy for compression is derived from the burning of a fuel, and the energy for operating the moving parts of the compressor is provided primarily by an external power source.

An object of the invention is to provide a refrigeration system wherein a change in temperature is employed in a compressor cylinder to operate a refrigeration cycle. Another object is to provide compressor apparatus in which the energy for compression is derived from heat preferably developed from the burning of a fuel, such as a combustible gas. Still another object is in the provision of compressor apparatus useful in a refrigeration system for compressing refrigerant, the compressor having a cylinder heated at one end and cooled at the other end, and, a piston freely fited within the cylinder and reciprocable therein for cyclically displacing refrigerant from the cooled end and then from the heated end of the cylinder. 1

Yet another object is in providing a compressor adapted to be connected between the evaporator and condenser in a refrigeration system and which provides a cylinder heated at one end and cooled at the other end, and a freely fitted piston reciprocable within the cylinder for cyclically displacing refrigerant from one end to the other end thereof, the cylinder being provided with an inlet port connected with the evaporator and a discharge port connected with the condenser, and in which both of the ports are located adjacent the cooled end portion of the cylinder whereby in the reciprocatory movement of the piston within the cylinder refrigerant is admitted from the evaporator, is displaced to the heated end of the cylinder and is thereafter displaced to the cooled end portion of the cylinder and it is pumped into the condenser. A further object of the invention is to provide apparatus as described, wherein the cylinder is equipped with internal fins and the piston with external fins, the fins being in overlapping, nested relation and providing extensive heat exchange surfaces for the refrigerant flowing thereover. Still a further object is to provide an external power source for reciprocating the piston within the cylinder, the power source having a relatively low energy output, and providing substantially only the power required for overcoming the friction of the moving elements of the compressor and for overcoming the friction of the gases flowing between the cylin der and the piston. Yet a further object is to provide compressor apparatus as described in which the heated end portion of the cylinder has heat supplied thereto from a burner and in which the cooled end portion of the cylinder is cooled by passing liquid thereabout in heat exchange relation therewith after that liquid has been used to cool the condenser in the refrigeration system. Additional objects and advantages will appear as the specification proceeds.

Embodiments of the invention are illustrated in the accompanying drawing, in which- Figure 1 is a vertical sectional view of a refrigeration system employing a compressor of this invention; and Figure 2 is a side view in elevation with parts thereof shown in section illustrating a modified form of compressor as it is employed in a refrigeration system.

The compressor apparatus illustrated in Figure l is designated generally with the letter A, and the refrigeration system in which it is employed is designated generally with the letter B. The refrigeration system B is for the most part conventional, and provides a condenser 10 and an evaporator coil 11 connected together through a conduit 12 having an expansion valve 13 interposed therein. A conduit 14 leads from the evaporator 11 to a manifold 15 through a pressure regulator valve 16, the inclusion of which in the system is optional. The condenser 111 is connected through a conduit 17 with a manifold 18. The condenser 14 is cooled by a water coil 19 mounted in heat exchange relation therewith and that is connected through a conduit 21 and control valve 21 with a source of water (not shown). Preferably, a bypass conduit 22 provided with a control valve 23 bypasses the control valve 21, and this bypass is utilized in initiating a refrigeration cycle in a manner that will be described hereinafter. It may be noted that a capillary tube 24 is connected at one end with the expansion valve 13 and at its other end is equipped with a thermally sensitive bulb in heat exchange relation with the flow conduit 14.

The compressor A is equipped with at least one cylinder, and preferably a plurality of cylinders. In the illustration of Figure 1, two cylinders are shown, and since these cylinders and their associated parts are identical in construction, only one will be described; and for purposes of identification the separate cylinders and their associated components will be designated by the letters a and b following each numeral. Specifically then, the cylinder on the left in Figure 1 will be designated with the numeral and letter 25a, while the cylinder on the right will be designated as 2515. Mounted for reciprocatory movement within the cylinders are the pistons 26a and 26b.

Mounted below the cylinders is a crank case 27 that has mounted for rotation therein upon the bearings 28 and 29 a crank shaft 31 that may be rotatably supported intermediate the ends thereof in a main bearing assembly 31 suitably supported or secured to the casing 27. The crank shaft 3% is coupled to the pistons 26a and 2617 respectively through the connecting rods 32a and 32b, and the piston rods 33a and 3312. At their upper ends the piston rods are secured to the pistons and at their lower ends are secured at the joints 3 4a and 34b to the connecting rods in a conventional manner as are the connecting rods secured to the crank shaft. Thus, when the crank shaft is rotated, the pistons are reciprocated within their cylinders.

Preferably, a low energy power source is employed for rotating the crank shaft 30 so as to reciprocate the pistons within their cylinders. Since the energy for compression is obtained from means to be subsequently described and that is apart from the power source, only sufficient power need be provided to the crank shaft 30 for overcoming the friction of the moving mechanical parts and for overcoming whatever friction may appear as refrigerant flows from one end to the other end of the cylinders and over the reciprocable pistons therein. A number of different arrangements might be provided for reciprocating the pistons through rotation of the crank shaft 39, and one exemplary arrangement is illustrated in Figure 1.

Show in Figure 1 i a sma meter 35 having s sly-iv ing member 36 fixed to the shaft 37a thereof. The driving member 36 is semicylindrical and receives therein an armature 37 that is directly connected to the crank shaft 30. As the motor 35 rotates, the driving member 36 is rotated and thereby causes the armature 37 to rotate,

which then in turn drives the crank shaft 30. The

members

36 and 37 might be a magnetic clutch, or if desired, the member 36 could be the field windings of a motor while the member 37 could be the rotor of the motor.

It is desired to provide the crank case 2.7 as a sealed unit and for this purpose a seal member 38 is provided about the rotor 37. The member 38 is sealingly secured to the casing 27 and is preferably formed of a HOD: magnetic material that will not interfere with the operation of the driving member 36 and the rotor 37. It will be apparent that a lubricant will ordinarily bepro= vided within the crank case chamber 39 for lubricating the crank shaft 30, as well as the connecting rods 32a and 32b and the piston rods 33a and 33b. Lubricant is not required within the cylinders 25a and 25b and, therefore, the piston rods 33a and 33b, where they extend through the bosses 40 and 41 of the casing 27, are preferably provided with packing glands so as to prevent the admission of lubricant from the crank case chamber 39 and into the cylinders.

Provided about the upper end portions of the cylinders 25a and 25b is acasing 42 that is rigidly secured to the cylinders at approximately the mid-portions thereof. The casing 42 is provided with spaced-apart openings 43 and 44 through the top wall thereof that are in alignment, respectively, with the upper ends of the cylinders 25a and 2512. A manifold 45 adapted to be secured to a source of combustible gas through a control valve 46 is equipped with burners 47 and 48 that are aligned, respectively, with the upper ends of the cylinders 25a and 25b. About the burners 47 and 48, the casing 42 provides an inwardly tapered annular flange 49 equipped at its lower end with an outwardly extending annular skirt 50. The casing provides a similar flange 51 and skirt portion 52 about the burner 48. The burners function in a conventional manner to burn a combustible fuel supplied thereto; secondary air for combustion entering the casing 42 through the apertures 43 and 44, and primary air being entrained in the fuel. The casing 42 is pro vided with an exhaust port 53 through which the products of combustion are removed from the chamber defined by the casing 42.

While the upper end portions of the cylinders are heated, the lower end portions thereof are cooled. To accomplish this result, preferably cooling coils 54a and 541) are provided, respectively, about the cylinder ends, and these coils are connected together in series by a conduit 55. Liquid for cooling the cylinders is supplied ,to the coil 54b through the conduit 56 that is connected with the cooling coil 19 in the condenser 10. The liquid, which ordinarily will be water, may be discharged .to waste through the outlet conduit 57 that is connected to the coil -54a. While the cooling coils are shown con nected in'series, it will be appreciated that a parallel arrangement might be provided, although ordinarily a series water flow path will be preferable.

To facilitate heat exchange with the refrigerant within the cylinders '25aand 25b, the upper end portions of these cylinders are provided with external fins 58a and 58b. Each of the cylinders internally is provided with internal fins 59a and 59b that extend longitudinally .of the cylinders. "The internal heat exchange fins are oriented about the cylinders in spaced-apart relation, and overlapping the same and intermeshed in nesting relation therewith are the external fins 60a and 6012 that are provided by each of the pistons. The pistons are freely fitted .within the .cylinders so that they reciprocate therein without engagement between the internal and external fins being provided. Therefore, fluid within the cylinders is free .topass from one end .to' the other end thereofas the pistons reciprocate. Preferably, the cylinders and their pistons are cylindrical throughout the central portions thereof, as shown in Figure 1, and have end sections attached thereto of conical configuration.

At their lower ends, the cylinder 25a is provided with an inlet port 61a communicating with the manifold 15 through a control valve 62a, and the cylinder 25b has an inlet port 61b that communicates with the manifold 15 through a control valve 62b. Similarly, each of the cylinders is provided respectively with outlet ports 63a and 63b communicating with the manifold .18 through control valves 64a and 64b. Refrigerant is admitted into the lower end portions of the cylinders through the inlet ports that communicate with the manifold 15 which in turn communicates with the conduit 14 and evaporator 11. Compressed refrigerant is expelled from the cylinders through the discharge ports that communicate with the manifold 18, which in turn is connected to the condenser 10.

In many cases sufficient refrigeration can be obtained from the elements thus far described, but where it is desired to reach lower. pressures, a pressure multiplier designated generally with the numeral 65 may be employed. Since pressure multipliers are well known in the art, a detailed showing thereof has not been set forth and a detailed description will not be provided. It is believed sufficient to say that a pressure multiplier, when employed as shown generally in the drawings, will allow a different pressure level to exist in the compression cylinders 25a and 25b than that which exists in the refrigeration system. Furthermore, with such an arrangement the ratio ofpressures may be different, if so desired, between the high pressure occurring in the refrigerant cycle and the low pressure occurring in the refrigeration cycle, and that ratio occurring in the compressor cycle.

Pressure-multiplying device 65 might take the form of a piston-operated compressor in which the compressed gas'from the cylinders operate on a piston of one diameter to move a piston of a different diameter through a different stroke.

Operation In operation of the apparatus the motor 35 is first energized to rotate the crank shaft 34 and to reciprocate the pistons 26g and 2 6]; within their respective cylinders. At approximately the same time, the control valve 4-6 iswopened to supply a combustible gas to the burners 47 anddfi which are then ignited. It will be appreciated that a pilot or pilot burners .might be arranged with the burners 47 ,and 48 a conventional manner to facilitate the ignition of the combustible gas supplied thereto. Such pilots have not been illustrated, however, for purposes of simplifying the structural showing. The auxiliary water control valve .23 is then opened to permit water to flow through the coil 19 to cool the condenser 10 and to also permit the water to flow through the cooling coils 5.4a and 54b to cool the lowerend portions of the cylindens. The purpose of the bypass 2.2 and its flow control valve 23 is to permit only a relatively small amount of water to flow initially .while the refrigeration cycle is placed in operation. With these steps taken, the upper end portions of the cylinders are heated while the lower end portions thereof are cooled, and at the same time the condenser 10 is cooled.

.Ener-gizingthe motor 35 causes the pistons to reciprocate within their cylinders, and such reciprocation causes adisplaceme-nt of the .fiuid within the cylinders,- first from one end thereof to :the other end, and thereafter to the first end. Reciprocation of the pistons causes cyclic repetition of this fluid fiow vor fluid displacement within the cylinders. ;In one position of the pistons in the cylinders, refrigerant is drawn into the cylinders from the evaporator 1-1, and after the compression of that refrigerant and following a reciprocation of the pistons, the

fluid is dischargedthrough the outlet ports and is pumped into the condenser 10.

In the position of the pistons, as is shown in Figure l, the piston 26a is in substantially its uppermost position within its cylinder, while the piston 26b is in its lowermost position within its cylinder. Assuming the position of the piston 26a, the cavity of the cylinder 25a beneath the piston is filled with cool refrigerant that has been admitted through the suction valve 62a in the inlet port tilt: at approximately the suction pressure of the refrigeration system as that pressure is controlled by the valve 16. As the piston Zea moves downwardly to fill the cylinder cavity therehelow, it displaces the cold refrigerant and causes it to flow upwardly in heat transfer contact with the internal fins 59a of the cylinder and the external fins dila of the piston. The fins are progressively warmer toward the top of the cylinder, and as the refrigerant flows upwardly the temperature thereof is raised, and correspondingly, its pressure is raised so that a portion of the refrigerant in expanded condition is forced outwardly through the discharge valve 64a in the discharge port 63a and into the manifold 18, and from there into the condenser 10.

Stated another way, the refrigerant gas leaves and enters the cylinder from the cold end thereof. The gas entering the cylinder from the evaporator is cold and must be heated many hundreds of degrees in the upper end of the cylinder to increase the pressure. Discharging it at this high temperature into the condenser would require a very much oversized condenser, and to avoid this the gas is discharged at the bottom of the cylinder, and it is important that the portion of the gas which is discharged has never been heated or if it was partially heated, becomes cooled as it flows past the fins on the piston and cylinder.

Referring now to cylinder 25b and the position of the piston 26b therein, the major volume of the refrigerant in that cylinder is in the hot end thereof, and is thereby heated to a high temperature since the upper end portion of the cylinder is heated by the burner 48. Thus, the pressure of the heated refrigerant will increase. As the pressure increases, refrigerant is forced out of the cylinder through the discharge port 63b and its discharge valve 64b and through manifold 18 into the condenser 10. As the piston 26b rises in its cylinder, the heated refrigerant is displaced to the cooled end of the cylinder, and in its movement passes in heat transfer contact with the internal fins 59b of the cylinder and the external fins 60b of the piston. Since these fins are progressively cooler toward the cold end of the cylinder, the refrigerant is cooled thereby as it flows thereover. It will be appreciated that the fins 60b of the piston are progressively colder toward the bottom end thereof because those fins have been cooled by direct heat transfer at the cold end of the cylinder during the time the piston is within the lower or cooled end portion of the cylinder. During the time the refrigerant is transferring to the cold end of the cylinder, the refrigerant is cooled and the pressure thereof is reduced until a sufiiciently low pressure is reached to open the pressure regulating valve 16, and refrigerant will then be drawn in from the evaporator 11 and the evaporator will be cooled by this movement of the refrigerant.

This cyclic ope ation is repeated repetitiously with the resul that (36 temperature changes within the cylinders 25a and 25b serve to alternately draw suction refrigerant in through the suction valves 62a and 62b and to discharge it through the discharge valves 64a and 64b. Thus, the heat energy of the burners 47 and 48 is transferred directly into the compression of refrigerant through the utilization of an extremely small amount of power which is supplied by the external power source, or specifically, the motor 35. Actually, the only power that need be supplied by the external power source is that which is sufficient to overcome the friction of the me chanical components and of the flow of refrigerant past the pistons 26a and 26b.

It will be noted that with the construction of the compressor that is shown and that has been described, lubrication is not required above the piston rods 33a and 33b. Thus, lubricant may be kept from entering the hot end of the compressor, or specifically, the cylinders 25a and 25b. No lubricant is required within the cylinders for there is no mechanical contact between the pistons and the cylinder walls. Furthermore, there is a gradual change in temperature from the hot end portions of the cylinders to the cold end portions thereof, and this temperature gradient is constantly maintained so that the heat transfer may be augmented by fins, as described. In addition, the moving fins, or the fins provided by the pistons 26a and 26b, serve as moving regenerators with respect to the refrigerant, and as heat transfer units which alternately come in contact with the cold and hot end portions of the cylinder for further facilitating heat transfer. This combination of features results in minimizing the usual problems that are present in these structures, and also results in maximum utilization, as far as heat transfor is concerned, of the elements of the compressor.

The degree of cooling of the lower end portions of the cylinders 25a and 25!) may be varied as desired. Variations may be provided by controlling the volume of liquid flowing through the coils 54a and 541; (which are in good heat exchange relation with the cylinders and preferably in contact therewith), and might also be provided by varying the temperature of the liquid flowing therethrough. The greater the amount of cooling of the lower end portions of the cylinders, the greater will be the tendency for some of the refrigerant to condense into a liquid within the lower portions of the cylinders. However, no harm will be done by such liquid condensation since there is no problem presented by my compressor of small volumetric clearance. In the most extreme case where the lower end portions of the cylinders are cooled to a very low temperature, all of the condensation of the refrigerant may occur in the cylinders. In this case, the condensed refrigerant may be removed from each cylinder as a liquid and as it condenses during the compression stroke. In this arrangement, it is possible to eliminate the external condenser 1i) from the refrigeration system, and a trap or float valve will be arranged with the cylinders so that only liquid refrigerant can be drained therefrom. Therefore, if it is desired to cool the lower end portions of the cylinders to relatively low temperatures, the result will be a further simplification of the thermocompressor type of refrigeration system.

When once the refrigeration system is in operation, the bypass valve 23 may be closed if desired and the water flow control valve 21 opened to supply a greater volume of cooling water to the condenser 10 and. to the cooling coils about the cylinders. However, the valve 23 may be a relatively small valve of limited flow characteristics so that when opened, only a suificient amount of water flows to pass through the condenser which at such time is inoperative because no refrigerant is condensing in it and through the cooling coils 54b and 54a. This would maintain the bottom parts of the cylinders practically at water temperature since no great amount of heat can be transferred when there is no flow of gas through the system.

When flow of gas begins, the pressure in the condenser increases and a standard refrigeration water regulating valve 2]., which is pressure actuated in response to condenser temperature, opens and increases the water flow to the amount required to properly condense refrigerant in the condenser. Valve 23 can still pass its small amount of water without affecting the operation of valve 21.

The refrigeration system that is designated generally with the letter B functions in a conventional manner, and refrigerant that is condensed within the condenser 10 flows through the conduit 12 and is expanded through the evaporator coils 11 through the expansion valve 13. That expanded refrigerant enters the manifold 15 through the "7 pressure control valve 16, and after compression the cycle is completed by the supply of compressed refrigerant to the condenser 10, through the manifold 18.

In the structural arrangement shown in Figure 1, the cylinder and 25b are arranged in a parallel fashion. That is, each cylinder and its associated elements functions substantially independently of the other, and independently the cylinders and their pistons operate to draw refrigerant from the evaporator 11 and to supply it to the condenser 16'. In some instances, however, it may be desirable to connect the cylinders in a series or twostage arrangement so that the discharge from one cylinder enters the suction or inlet of the other cylinder. Twostage operation obtained in this manner would be effective to reduce the compression ratio in either cylinder or the temperature rise required, to approximately the square root of the over-all ratio of either pressure or temperature. It will be apparent that any number of stages that might be required may be employed in a serie arrangement, and that the operation of such Structures will be essentially the same as that described; and in each case, the refrigerant will be passed sequentially through all of the cylinder stages, the first stage in each case receiving suction refrigerant from the evaporator 11 and the last stage delivering the compressed refrigerant gas or liquid at high pressure to the refrigeration system. Such arrangements are, in essence, operative to produce substantially the same result as the pressure multiplier 65 that is shown in Figure l and that has been described hereinbefore. The decision as to whether single or multiple-stage compression is used will depend largely on the heat capacity of the metals available. Metals able to withstand temperatures of 1700 to 1800 P. will permit use of single-stage compression, while temperature limitations of about 1000 to 1100 F. will probably require multi-stage compression.

A structure of slightly modified character showing twostage compression is illustrated in Figure 2. In this form of the invention, substantially all of the elements are the same as those heretofore described, and except for the two-stage type of compression, the only difference resides in the exterior or external power source that is employed for rotating the crank shaft to reciprocate the pistons within their cylinders. It will be noted that the crank shaft 66 is slightly elongated, as is the casing 67 that houses the same. An extra crank portion is provided on the crank shaft 66 adjacent the connecting rod 68 that, in turn, is connected to the piston 70 which is mounted for reciprocable movement within the cylinder casing 71. All of these members are housed within the casing 67, as is shown in Figure 2.

The cylinder 71 is supported for pivotal movement at the mid-point thereof on pivot shaft 69, and adjacent the opposite ends thereof is provided with an inlet port 72 at its bottom end, and an inlet port 73 at its upper end. If desired, each of these ports may be controlled, respectively, by the

valves

74 and 75. The ports, through their valves, are connected to a flow conduit 76 in a parallel arrangement, and the flow conduit 76 at its opposite end is connected to the condenser 10 or to the conduit 17 which are, in effect, common, and this is the high pressure side of the refrigeration system. High pressure refrigerant is supplied through the conduit 76 to opposite ends of the cylinder 71.

The cylinder 71 is also provided adjacent its lower end with a discharge port 77, and adjacent its upper end with a discharge port 78. These ports are controlled, respectively, by the valves 79 and 81). The ports 77 and 78 are connected in parallel to a flow conduit 14, com municating with the evaporator 11, which is the low pressure or suction side of the refrigeration system. Connection of the cylinder 71 in this manner is effective to reciprocate the piston 70 through the force exerted thereagainst by the admission of high pressure refrigerant to the cylinder 71.

The cylinder casing 71 is pivoted about the pin or pivot shaft 69, and is pivoted by the reciprocatory movement of the piston 70 therein because that piston is rigidly connected to the rod 68 which, at its lower end, is swung through a closed are by the eccentric or crank to which it is secured. It is evident from Figure 2 that the cylinder casing 71 has the end portions thereof enclosed by rigidly supported valve casings 71a and 71b, respectively, each of which provides inlet and outlet ports adapted to align, respectively, with the

ports

72, 73 and 77, 78. As the cylinder casing 71 oscillates or pivots, the ports in the valve casings cyclically align with the respective inlet and outlet ports in the cylinder casing.

It is necessary to place the system in o eration before the cylinder 71 and its piston 70 in their operative arrangement can function to rotate the crank shaft 66, and thereby reciprocate the pistons within the cylinders 25a and 2512. Any suitable means may be provided for initiating rotation of the crank shaft 66, and an exemplary arrangement (which in this case is manual) is shown in Figure 2. It will be apparent that mechanical means, rather than manual, may be employed for starting rotation of the crank shaft 66 to place the system in operation.

In the form of the manual starter shown, the crank shaft 66 at one end thereof is connected through an overriding clutch (not Shown in detail) with a rotor 82 that is enclosed Within the casing 67 by a non-magnetic seal member 83. Surrounding the rotor 82 and shield 83 is a semicyclindrical driving member 84 that is connected to a crank 85 supported for rotation within a standard 86. The members 82 and 84 may be the same as those described hereinbefore with reference to Figure 1. The overriding clutch permits the crank unit to remain stationary after the unit has been started.

As has been brought out before, the cylinders 25a and 25b are connected in a series relation, and comprise together a two-stage compressor. This arrangement is accomplished by connecting together in a flow relation the outlet of the cylinder 25b with the inlet of the cylinder 25a through a manifold section 15a. The inlet of cylinder 25b is connected to the pressure regulator valve 16, as in the embodiment of Figure 1, and the outlet of the cylinder 25a is connected to the discharge manifold 18, also as in Figure 1. The operation of the cylinders is the same as described with reference to Figure 1, except that two-stage compression is provided rather than singlestage.

In operation ,of this refrigeration system, the same steps are carried out initially as those that have been described with reference to the Figure l embodiment. That is to say, the valve 46 is opened and the burners ignited to heat the upper end portions of the cylinders 25:: and 25b. Similarly, the bypass valve 23 is opened to supply a water coolant to the condenser coils 19 and to the coils 54a and 5412 about the cylinders. The crank 85 is then manually rotated to commence rotation of the crank shaft 66, and to reciprocate the pistons within the cylinders 25a and 2512. After a short period of manual rotation of the crank 85, the system will be placed in operation and cranking can be discontinued.

Once the system is in operation, the piston 70 is reciprocated by the pressure differential of the refrigerant in the refrigeration system as such pressure differential is produced by the compressor. Reciprocation of the piston 70 will, of course, rotate the crank shaft 66 to which it is operatively connected, and the system will thereafter function as described before. The cylinder 71 may be connected as shown, and may also be connected across either of the stages of the compressor, or across both stages thereof, in the event that a two-stage system is employed.

While in the foregoing specification embodiments of the invention have been set forth and described in considerable detail for purposes of adequately illustrating and describing the invention, it will be apparent to those skilled in the art that numerous changes may be made in these details without departing from the spirit and principles of the invention.

I claim:

1. In apparatus of the character described for eifectuating expansion and contraction of a fluid by heat transfer thereto, a cylinder heated at one end portion and cooled at the other end portion and provided with an inlet and an outlet, and a freely fitted piston reciprocable within said chamber for displacing fluid from one end to the other end thereof, said cylinder being provided with internal fins and said piston with external fins to expedite heat transfer with fluids passing thereover.

2. Apparatus as described in claim 1 in which said internal and external fins are in overlapping, nested relation.

3. In a compressor structure wherein the change of state in a fluid is derived from a heat transfer therewith, a cylinder provided with an inlet for admitting expanded fluid thereto and with an outlet for discharging a compressed fluid therefrom, means for heating one end portion of said cylinder, means for cooling the other end portion of said cylinder, said inlet and outlet being located at the cooled end portion of said cylinder, a freely fitted piston mounted for reciprocation within said cylinder for displacing fiuid from one end to the other end thereof, said cylinder being equipped with internal fins and said piston with external fins, and means for reciprocating said piston within said cylinder.

4. The apparatus of claim 3 in which said internal and external fins are in overlapping, nested relation.

5. In a refrigeration system having an evaporator, a condenser and conduit means interconnecting the same, a compressor interposed in said conduit means for receiving refrigerant from said evaporator and for delivering it to said condenser, comprising a cylinder, means for heating said cylinder at one end portion thereof, means for cooling said cylinder at the other end portion thereof, a valve-equipped inlet at said cooled end portion connected to said evaporator, a valve-equipped outlet at said cooled end portion connected to said condenser, a freely fitted piston reciprocable within said cylinder for cyclically displacing admitted refrigerant from the cooled end portion to the heated end portion of the cylinder and heated refrigerant from the heated end portion to the cooled end portion of the cylinder, said cylinder being equipped with internal fins and said piston with external fins, and means for reciprocating said piston to effectuate said displacement.

6. In a refrigeration system having an evaporator, a condenser and conduit means interconnecting the same, a multiple stage compressor interposed in said conduit means for receiving refrigerant from said evaporator and for delivering it to said condenser, comprising at least two cylinders, means for heating one end portion of each of said cylinders, means for cooling the other end portion of each of said cylinders, inlet and outlet means for each cylinder at the cooled end portion thereof, the inlet of one of said cylinders being connected to said evaporator, the outlet of the other cylinder being connected to said condenser, conduit means connecting the outlet of the first cylinder with the inlet of the second, a freely fitted piston reciprocable within each of said cylinders for cyclically displacing refrigerant admitted at the cooled end portion thereof to the heated end portion and heated refrigerant from the heated end portion of the cylinder to the cooled end portion thereof, said cylinders being equipped with internal fins and said pistons with external fins, and means for reciprocating each of said pistons to effectuate said displacement.

7. In a refrigeration system having an evaporator, a condenser and conduit means interconnecting the same,

a compressor interposed in said conduit means for receiving refrigerant from said evaporator and for delivering it to said condenser, comprising a cylinder, means for heating said cylinder at the upper end portion thereof, means for cooling said cylinder at the lower end portion thereof, a valve-equipped inlet at said cooled end portion connected to said evaporator, a valve-equipped outlet at said cooled end portion connected to said condenser, a freely fitted piston reciprocable within said cylinder for cyclically displacing admitted refrigerant from the cooled'end portion to the heated end portion of the cylinder and heated refrigerant from the heated end portion to the cooled end portion of the cylinder, said cylinder being equipped with internal fins and said piston equipped with external fins, and means for reciprocating said piston to effectuate said displacement.

8. The system of claim 7 wherein the means for heating said cylinder at one end portion thereof comprises a casing supported on said cylinder at approximately the mid-portion thereof, an opening in the top wall of said casing aligned with the top of said cylinder, and gas burner means extending into said casing through said opening. i

9. The system of claim 7 wherein the said cylinder has a conical-shaped top portion and said casing is provided with an internally depending skirt about said opening to direct heated gas from said burner about said cylinder, and means for exhausting the products of combustion from said burner.

10. The system of claim 7 wherein the said cylinder is provided with external fins about its top portion to facilitate heat transfer into said cylinder from said burner.

'11. In a refrigeration system having an evaporator, a condenser and conduit means interconnecting the same, a compressor interposed in said conduit means for receiving refrigerant from said evaporator and for delivering it to said condenser, comprising a cylinder, means for heating said cylinder at one end portion thereof, means for cooling said cylinder at the other end portion thereof, a valve-equipped [inlet at said cooled end portion connected to said evaporator, a valve-equipped outlet at said cooled end portion connected to said condenser, a freely fitted piston reciprocable within said cylinder for cyclically displacing admitted refrigerant from the cooled end portion to the heated end portion of the cylinder and heated refrigerant from the heated end portion to the cooled end portion of the cylinder, said condenser being liquid cooled and said means for cooling an end portion of said cylinder comprising means for flowing liquidused to cool said condenser in heat exchange relation with said cooled end portion of said cylinder, and means for reciprocating said piston to effectuate said displacement.

12. The system of claim 11 in which a cooling coil is provided in heat exchange relation about an end portion of said cylinder, said coil being connected to said liquid-cooled condenser for receiving cooling liquid therefrom.

13. The system of claim 11 in which said compressor is provided with at least two cylinders and in which series connected cooling coils are provided in heat exchange relation about the respective end portions of the cylinders, one of said coils being connected to the liquid-cooled condenser for receiving cooling liquid therefrom.

14. The system of claim 11 in which flow regulation means are interposed in the conduit supplying cooling liquid to said condenser, said flow regulating means comprising a by-pass control valve and a larger capacity, refrigerant pressure-actuated valve.

15. In a refrigeration system having an evaporator, a con-denser and conduit means interconnecting the same, a compressor interposed in said conduit means for receiving refrigerant from said evaporator and for delivering it to said condenser, comprising a cylinder, means for heating said cylinder in one end portion thereof, means v for cooling said cylinder at the other end portion thereof,

a valve equipped inlet at said cooled end portion, ICOH'. nected to said evaporator, a valve-equipped outlet at said cooled end portion connected to said condenser, a freely fitted piston reciprocable Within said cylinder for cyclically displacing admitted refrigerant from the cooled end portion to the heated end portion of the cylinder and heated refrigerant from the heated end portion to the cooled end portion of the cylinder, and means for reciprocating said piston comprising a driven cylinder equipped With a reciprocable piston operatively connected to said first-mentioned piston for reciprocating the same, said last-mentioned cylinder being connected adjacent opposite ends thereof With the high pressure side of said refrigerant system and being provided with valveequippedports connected with the low pressure side of :said system, and in which means are provided for initiating operation of said compressor.

16, In a refrigeration system having an evaporator, a condenser and conduit means interconnecting the same, a compressor interposed in said conduit means for receiving refrigerant from said evaporator and for delivering it to said condenser, comprising a cylinder, means for heating saideylin'der in. one end portion thereof, means for cooling :saidcylinder at the other end portion thereof, a valve-equipped inlet at the cooled end portion connected to said evaporator, a valve-equipped'outlet at the said cooled end portion connected to said condenser, a freely fitted piston reciprocable within said cylinder for cyclically displacing admitted refrigerant from the cooled end portion to the heated end portion of the cylinder and heated refrigerant from the heated end portion to the cooled end portion of the cylinder; pressure-multiplier means being provided in said conduit means to provide a pressure differential between said cylinder and evaporator and condenser,- and means 'for reciprocating :said piston to effectuate said displacement.

References Cited iii the file of this patent UNITED STATES PATENTS