US2047039A - Refrigerating machine - Google Patents

Description

July 7, 1936. A. R. STEVENSON, JR

REFRIGERATING MACHINE 2 Sheets-Sheet 1 Filed Dec. 5', 1934 Ila lnQentor Alexander- R. Stevenson Jr,

. .7 E, by His Attorney.

, July 1935- A. R. STEVENSON, JR 2,047,039

REFRIGERA'IIING MACHINE Filed Dec. 5, 1934 2 Sheets-Sheet 2 I nventor-i Alexander R. Stevenson Jr;

H rif /Attorney.

Patented July 7, 193% REFEIGERATING MACHINE Alexander R. Stevenson, Jr., Schenectady, N. Y.; I

assignor to General Electric @ompany, a corporation of New York My invention relates to refrigerating machines of the type in which a gaseous refrigerant is utilized without liquefaction.

Refrigerating machines which circulate a gaseous refrigerant through .the refrigerant cycle without liquefaction may comprise a high pressure refrigerant circuit and a low pressure refrigerant circuit, a device or devices to compress refrigerant received from the low pressure circuit '10 and deliver it to the high pressure circuit, and to expand refrigerant received from the high pressure circuit and deliver it to the low' pressure circuit. ,These devices may be combined in a single machine for performing both expanding 5 and compressing operations. Such a combined machine is termed a wattless compressor since no net work is done on the refrigerant thereby. The .expanded refrigerant and compressed refrigerant are delivered to the low and high pressure circuits respectively by scavenging pumps or fans arranged in the circuits. The compressed refrigerant is cooled in the high pressure circuit by a suitable heat exchanger and the expanded refrigerant. in the low pressure circuit is' utilized to absorb heat from a cooling element. The

continuous operation of the expanding and compressing devices tends to equalize the pressures in the high and low pressure circuits and, in order to maintain the desired pressure difference between the circuits, a compressor or pump is provided which continually operates to pump 1'8.- frigerant from the low pressure circuit to the high pressure circuit. This compressor is termed a power compressor. It has been proposed to construct a machine arranged to perform the the functions of compression and expansion and of maintaining the pressure difference between the high and lowpressure circuits. In the machines thus far proposed it has been necessary to provide pressure actuated ports through which the refrigerant must pass during the scavenging operation. Such an arrangement is undesirable because it produces excessive losses due to turbulence of the gas during the scavenging operation. Accordingly, it is an object of my invention to provide an improved refrigerating machine of the type above referred to in which gaseous refrigerant is utilized without liquefaction which shall v require only a single machine for performing all the functions of compression and expansion.

Another object'of my invention is to provide a refrigerating machine utilizing a gaseous refrigerant without liquefaction, which shall perform 35 the functions of a wattless and a power compressor, and which shall provide an unobstructed path for the scavenging gases.

A further object of my invention is to provide a refrigerating machine utilizing a gaseous refrigerant without liquefaction incorporating an im- 5 proved and well-balanced wattless compressor.

Further objects and advantages of my invention will become apparent as the following de-. scription proceeds, and the features of novelty which characterize my invention will be pointed 10 out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawingsin which Fig. 1 is a diagrammatic view of a refrigerating machine embodying my invention; Fig. 2 is an enlarged sectional plan view of the compressor shown in Fig. 1; and Fig. 3 is a sectional view on the line 3-3 of Fig. 2.

Referring now to Fig. 1, I have shown a refrig- 2o crating machine including a compressor Hi having stationary cylinders II and Ila and provided with a driving motor l2. The compressor I0 is" arranged to alternately'expand and compress refrigerant, refrigerant being compressed in the cylinder II at the same time that refrigerant is being expanded in the cylinder I la and vice versa. A ,high pressure refrigerant circuit and a low pressure refrigerant circuit are connected to the compressor. The highpressiire circuit includes 30 a heat exchanger or cooling coil I 3 for cooling the hot compressed gas received fromthe compressor and ascavenging fan M for scavenging the cylinders ll andila and replacing the hot compressed refrigerant therein with refrigerant at the some pressure which hasbeen cooled in the coil I3. During the scavenging operation hot compressed-gas is delivered from the cylinders alternately-throughconduits l6 and l6a to the conduit l5, and is circulated by the fan I4 through the coil l3 where. it is cooled before returning through a conduit 'l'l 'and alternately through conduits l8 and 18a. to'the compressor, the path of the high'pressure refrigerant being indicated by arrows. The low pressure circuit includes a refrigerating coil l9arranged' to .0001 any desired medium and ascavenging fan 20 for scavenging the cylinders and Ila and replacing the cold expanded gas therein with refrigerant at substantially the same pressure warmed by passage through the coil l9. During the scavenging operation, cold expanded gas is delivered from the cylinders alternately through conduits 2| and 2 la to the coil l9, and is warmed in the refrigerating coil l9 before being returned through a conduit 22 r and alternately through conduits 28 and 28a to the compressor. The operation of the compressor III which supplies hot compressed gas to the high pressure circuit and cold expanded gas to the low pressure circuit tends to equalize the pressures in the circuits. In order to maintain the desired pressure difference between the circuits, the compressor I0 is constructed sothat it will pump refrigerant from a connection 24 between the conduit 22 and the casing of the compressor in the low pressure circuit through connections 25 and 250. into the conduit I! of the high pressure circuit, thereby maintaining the desired pressure difference.

Referring now to Fig. 2 of the drawings, the compressor ||l including the cylinders i and Na is symmetrical the cylinder II and all parts of the compressor to the left of a shaft 28 driven by the motor |2 being similar to and symmetrical with the cylinder II a and all parts of the compressor to the right of the shaft 28. In this description the symmetrical parts to the right of the shaft 28 have been designated by applying the letter a to the same numerals as the parts to the left thereof. The moving parts of the compressor are balanced, so that the equal masses at all times move in opposite directions and at equal rates of acceleration. Cylinders 21 and 21a are arranged within the cylinders I I and I la and pistons 28 and 28a are arranged to move within the cylinders 21 and 21a. Cylinders 21 and 21a are driven at the same rate and in the opposite direction from the pistons 28 and 28a, so that when one of the pistons is on its expansion stroke the other is on its compression stroke. The pistons and the cylinders are driven by Scotch yoke connections. As shown in Figs. 2 and 3, the driving mechanism for the cylinders 21 and 21a includes yokes 29 and 29a secured together by bolts 30 and blocks 3| arranged to slide transversely of the cylinder axis betwen guides 32 and 321: formed in the yokes 29 and 29a respectively. A reciprocating motion is imparted to the cylinders through eccentrics 33 driven by the shaft 26 and mounted in the blocks 3| on roller bearings 34 arranged between cages 35 and 38. A similar mechanism is provided for driving the pistons 28 and 28a and includes a yoke 81 formed integrally with the pistons 28 and 28a. Sliding blocks or cross-heads 38 are mounted in guides 39 and 38a in the sides of the yoke 31, and a reciprocating motion is imparted to the pistons by eccentrics 40 mounted in the blocks 38 and roller bearings 4| having inner bearing races 42 and outer bearing races 43. placed 180 and have the same eccentricity, and the reciprocating mass including the cylinders 21 and 21a driven by the eccentrics 33 is the same asv the reciprocating mass including the cylinders 28 and 28a driven by the eccentrics 48. As the eccentrics 33 and 40 are mounted apart on the shaft 28, the pistons and cylinders are'driven in opposite directions at equal rates of acceleration and the reciprocating forces are therefore balanced. Fly-wheels 44 are provided on the shaft 26 on either side of the Scotch yoke driving mechanism.

The compressor is shown with the cylinders 21 and 21a in their extreme left-hand positions and,

The eccentrics 33 and 40 are dispression stroke, and in communication with the high pressure circuit.

The cylinder 21 is in communication with the low pressure circuit of the refrigerating machine through ports 48 and 48 connected to the low 5 pressure conduits 28 and 2| respectively, and which register with ports 41 and 48 respectively in thecylinder 21 and with ports 49 and 50 in a cylindrical extension 8| on the piston 28. The scavenging fan 20 circulates low pressure gas warmed in the'coil l8 to cylinder- 21 through the ports 48 and 88 and forces out cold expanded gas through the ports 48 into the conduit 2| through which it is conveyed to the refrigerating coil IS.

The cylinder 21a is in communication with the 15 high pressure circuit through ports 52a and'53a communicating with the high pressure conduits |8a and IM respectively and registering with ports 54a and 55a in the piston 21a and with ports 49a and 50a in extension 8| of the piston 20 28a. High pressure scavenging gas circulated by the fan |4 flows through the coil I3, is cooled therein and then'flows through the conduit |8a through registering'ports 52a, 54a and 49a and then through the cylinder 21 around a baflle 25 56a therein and forces the hot compressed gas out through the registering ports 50a, 55a and 53a and through conduit |8a to the conduit IS. The bailie 86a divides the space within the cylindrical extension 5| of the piston into a U-shaped passage having a substantially uniform crosssectional area. This arrangement whereby a baille is provided within the cylinder to provide a passage of substantially uniform cross-sec tional area for the scavenging gas is described 35 and claimed in a co-pending appliction of Robert U. Berry, Serial No. 756,111, filed December 5, 1934, and assigned to the General Electric Company, assignee of this present application. I do not, therefore, claim herein anything described or claimed in the said Berry application which is to be regarded as prior art with respect to this present application, my present invention relat- 'ing to an improved arrangement for combining the wattless and power compressors and for balancing the wattless compressor of a refrigerating As has been pointed out, the operation within the right and left-hand cylinders II and Na is identical and, while one cylinder is compressing the other one is expanding the refrigerant gas. It will be evident, therefore, that when the cylinders 21 and 21a and the pistons 28 and 28a are at the opposite ends of' their strokes, the 55 cylinder 21 will be in communication with the I high pressure circuit of the refrigerating machine and the cylinder 21a will be in communication with the low pressure circuit of the refrigerating machine. The scavenging of the compressed and expanded gas for this opposite position of the cylinders and pistons is, therefore, the same as that explained above for the position shown in the drawings. These compressing .andexpanding operations will continue throughout the 65 operation of the compressor. A consideration of this operation will disclose that it tendsto equalize the pressures between the high pressure and low pressure circuits. For example, when the hot compressed gas is replaced during 70 the scavenging operation with cool compressed gas, a greater weight of gas is left in the cylinder than was present at the end of the compression stroke. This cooled gas is then expanded and delivered on the next scavenging 75 operation to the low pressurecircuit when it is replaced by warmer low pressure gas. A. greater weight of gas is thus added to the low pressure circuit than is taken therefrom. A repetition of this operation results in a-continual drain of refrigerant from the high pressure circuit to the low pressure circuit. For this reasong it is necessary to provide an arrangement for returning refrigerant from the low pressure circuit to the high pressure circuit in order to maintain the desired difference in pressure between said circuits. 1

In accordance with. my inventionI provide ad'- ditional ports in the cylinders 21 and 21a and utilizethe movement of the pistons 28 and 28a to pump refrigerant directly from the low pressure circuit to the high pressure circuit when the cylinders and pistons are intermediate their scavenging positions.

In the illustrated embodiment of my invention shown in Fig. 2 I provide normally closed pressure operated valves or ports hi and bl'a in heads at and the of the cylinders 21'! and 2%; respectively. These valves are designed to open when the pressure within the cylinders 2i and his exceeds the pressure in the high pressure circuit by a predetermined amount, the high pressure circuit being connected with chambers 59 and the in the ends of the cylinders it and Ho by the conduits tit and 250. I also'provide pressure operated valves db and tile for providing i lli munication between the cylinders 2i andt'ia and the low pressure circuit when the pressure therein is a. predetermined amount less than the pressure within the low pressure circuit. The valves fit and the are arranged at the ends of passages ti and tie in the pistons it and its. In order to provide communication between the low pressure circuit and the passages ti and ii to, I enclose the Scotch yoke driving mechanisms within a sealed casing comprising athousing t2 and end plates t3 and 63a formed integrally with the cylinders ii and i to: respectively, the connection It and a pluralityof ducts 64 providing communication between the low pressure circuit and the interior of the housing 62. It will be seen from a consideration of-Fig. 3 that the refrigerant is free to pass through the spaces between the blocks ti and the yokes 29 and 29a. In order to provide communication between the interior of the housing 62 and passages ti and tie, I

. provide ducts 65 and 65a. respectively in the yokes 3ft;

When the piston ,28 and the cylinder 21! are moved from the right hand position in which they are shown, the ports and 46 in the cylinder H are closed by movement of the cylinder II, and the compression of the gas within this cylinder begins. The pressure within the cylinder 2?? becomes equal to that within the high pressure circuit before the piston reaches the end of its stroke. The pressure, therefore, increases above the pressure of the high pressure circuit and a volume of gas is forced out through the valve ti into the chamber 59 and thence through the conduit 25' to the high pressure circuit. The cylinder 21 and piston 28 then reach the ends of their strokes and open the ports 52 and 53, and the pressure between the cylinder ti and the high pressure circuit is equalized during the scavenging operation. (in the return stroke the ports 52 and 53 are closed and the gas in the cylinder is expanded until its pressure becomes less than that within the low pressure circuit. Further movement of the cylinder and.

piston will then tend to further decrease this pressure and will draw refrigerant into the cylinder 21 through the valve 60 from the housing 62 communicating with the low pressure circuit,

thereby increasing the amount of gas within the cylinder 21. On the scavenging operation the pressure within the cylinder 21 and the low pressure circuit will be equalized due to the opening of the ports 45 and 46, and the compression cycle will be repeated. From the foregoing it is seen that by operation of the piston 28 and the cylinder 2'! gas is continuously removed from the low pressure circuit and pumped by the piston 28 into the high pressure circuit through the valves 60 and 51 respectively. The pumping operation on-the right end of the compressor within the cylinder Me is exactly the same as that just described within the cylinder 21, the valves bid and 6011 operating in the same manner as the valves bl! and 6t. From a consideration of the operation of the compressor it will clearly be seen that the power and wattless compressors have been combined in one machine, and that the scavenging operations are performed without the necessity for the passage of scavenging gas through the pressure operated valve or the like, and that the function of maintaining the pressure difierence between the high and low pressure circuits is performed by the machine through ports separate from the ports utilized during the scavenging operation. The difference in pressure between the high and low pressure circuit is determined by the dimensions of the cylinders 2i and Na and of the pistons 28 and flea; and by proper design a refrigerating machine may be provided to operate at any desired pressure difien. ence.

During operation of the refrigerating machine shown in Fig. 1 the cooling coil it is arranged to be cooled by a fluid such as water or air circulating thereover. The coil 9 is placed in a refrigerator cabinet, or in contact with any medium to be cooled. The compressor ill is operated continuously or at intervals, as desired to maintain the required temperature of the coil l9.

The scavengingfans M and 20 operate continuously during operation of the compressor it.

From the foregoing it is apparent that I have provided an improved refrigerating machine utilizing a gaseous refrigerant without liquefaction and embodying a balanced compressor for performing all the functions of compression, expansion and maintenance of pressure difference in the system.

While I have described one embodiment of my invention, I do not desire myinvention to be limited to the particular construction shown and described," and I. intend in the appended claims to cover all modificationswithin the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:-.-

l. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder having high and lowv pressure intake and exhaust ports and a piston movable therein for compressing refrigerant from said. low pressure circuit and for expanding refrigerant from said high pressure circuit, scavenging means for utilizing said high and low pressure ports for circulating gas compressed in said cylinder through said high pressure circuit and for circulating gas expanded in said cylinder through prising a low pressure refrigerant circuit and ahigh pressure refrigerant circuit, means including a cylinder having high and low pressure intake and exhaust ports and a piston movable therein for compressing refrigerant from said low pressure circuit and for expanding refrigerant from said high pressure circuit, scavenging means utilizing said high and low pressure ports for circulating gas compressed in said cylinder through said high pressure circuit and for circulating gas expanded in said cylinder through said low pressure circuit, means for cooling hot compressed refrigerant in said high pressure circuit, means utilizing the cold expanded refrigerant in said low pressure circuit for producing refrigeration and means separate from said scavenging means and utilizing the movement of said piston for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

3. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder'having'high and low pressure intake and exhaust ports and a piston movable therein for compressing refrigerant from said low pressure circuit and for expanding refrigerant from said high pressure circuit, scavenging means utilizing said high and low pressure ports for circulating gas compressed in said cylinder through said high pressure circuit and for circulating gas expanded in said cylinder through said low pressure circuit, and means including pressure operated portsin said cylinder separate from said last mentioned means and utilizing the movement of said piston for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

4. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder having high and low pressure in take and exhaust ports and a piston movable therein for compressing refrigerant from said low pressure circuit on one stroke of said piston and for expanding refrigerant from said high pressure circuit on the other stroke of said pis-,

ton, means arranged in said high pressure circuit and utilizing said high pressure ports for scavenging said cylinder at the end of the compression stroke of said piston, means arranged in said low pressure circuit and utilizing said low pressure ports for scavenging said cylinder at the end of the expansion stroke of said piston, and means separate from said scavenging means and utiliz-\ ing the movement of said piston intermediate the ends of thestrokes thereof for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

5. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder having high and low pressure intake and exhaust ports and a piston movable therein for compressing refrigerant from said low pressure circuit on one stroke of said piston and for expanding refrigerant from said high pressure circuiton the other stroke of said pistonymeans arranged in said high pressure circuit and utilizing said high pressure ports for scavenging said cylinder at the end of the compression stroke of said piston, means arranged in said low pressure circuit and utilizing said low pressure ports for scavenging said cylinder at the end of the expansion stroke of said piston, means for cooling the compressed gas in said high pressure circuit, means utilizing the cooling effect of the expanded gas in said low pressure circuit for producing refrigeration, and means separate from said scavenging means and utilizing the movement of said piston intermediate the ends of the strokes thereof for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

6. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder having high and low pressure intake and exhaust ports and a piston movable therein for compressing refrigerant from said low pressure circuit on one stroke of said piston and for expanding refrigerant from said high pressure circuit on the other stroke of said piston, means arranged in said high pressure circuit utilizing said high pressure ports for scavenging said cylinder at the end of the compression stroke of said piston, means arranged in said low pressure circuit and utilizing said low pressure ports for scavenging said cylinder at the end of the expansion stroke of said piston, means for cooling the compressed gas in said high pressure circuit, means utilizing the cooling effect of the expanded gas in said low pressure circuit for producing refrigeration, and means including pressure operated ports separate from said scavenging means and utilizing the movement of said piston intermediate the ends of the strokes thereof for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

7. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigerant on the other stroke thereof, means including ports in said cylinder for providing communication between said cylinder and said low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at the end of the compression stroke of said piston, means utilizing said low pressure circuit for scavenging said cylinder at the end of said expansion stroke, means utilizing said high pressure circuit for scavenging said cylinder at the end of said compression stroke, and means including ports in said cylinder in addition to said above-mentioned ports and utilizing the movement of said piston for maintaining a difference in pressure between said circuits.

aosaoaa 8. A refrigerating machine of the utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigerant on the other stroke thereof, means including ports in said cylinder for providing communication between said cylinder and said low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at the end of the compression stroke of said piston, means utiliz-- utilizing the cooling eflect of the scavenged expanded gas for producing refrigeration, means utilizing said high pressure circuit for scavenging said cylinder at the end of said compression stroke, means arranged in said high pressure circuit for cooling the scavenged compressed gas, and means including ports in said cylinder in addition to said above-mentioned ports and utilizing'the movement of said piston for maintaining a diderence in pressure between said circuits.

9. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerantcircuit and a high pressure refrigerant circuit, means including a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigeranton the other stroke thereof, means including ports in said cylinder for providing communication between said cylinder andsaid low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at theend of the compression stroke of said piston, means utilizing said low pressure circuit for scavenging said cylinder at the end of said expansion stroke, means utilizing said high pressure circuit for scavenging said cylinder at the end of said com: pression stroke, and means including a port in said piston and an additional port in said cylinder and utilizing the movement of said piston for maintaining a difference in pressure between said circuits. I

10. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigerant on the other stroke thereof, means including ports in said cylinder for providing communication between said cylinder and said low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at the end of the compression stroke of said piston, means utilizing said low pressure circuit for scavenging said cylinder at the end of said expansion stroke, means utilizing said high pressure circuit for scavenging said cylinder at the end of said com: pression stroke, and means including ports in addition to said first mentioned ports for withdrawing gas from said low pressure circuit prior to scavenging expanded gas from said cylinder and for adding gas to said high pressure circuit prior to scavenging compressed gas from said cylinder to maintain a difference in pressure between said circuits.

11. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including, a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigerant on the other stroke thereof, means including ports in said cylinder actuated by said piston for providing communication between said cylinder and said low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at the end of the compression stroke of said piston, means utilizing said low pressure circuit for scavenging said cylinder at the end of said expansion stroke, means utilizing said at the end of said compression stroke, means including a pressure operated port 'arranged in high pressure circuit for scavenging said cylinder to said piston for withdrawing refrigerant from said low pressure circuit prior to the'scavenging of expanded gas from said cylinder, and means including a pressure operated port arranged in said cylinder for adding refrigerant to said high pressure circuit prior to the scavenging compressed gas from said cylinder to maintain a difference in pressure between said circuits.

12. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigerant on the other stroke thereof, means including ports in said cylinder for providing communication between said cylinder and said' low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at the end of the compression stroke of said piston, means utilizing said low pressure circuit for scavenging said cylinder at the end of said expansion stroke, means utilizing said high pressure circuit for scavenging said cylinder at the end of said compression stroke, a driving connection for said piston, aclos'ed easing surrounding said driving connection and communicating with said low pressure circuit, and means utilizing the movement of said piston and including a port in said cylinder communicating with said casing and a port in addition to said above mentioned ports communicating with said high pressure circuit for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

13. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, means including a cylinder and a piston movable therein for expanding refrigerant on one stroke of said piston and for compressing refrigerant on the other stroke thereof, means including ports in said cylinder for providing communication between said cylinder and said low pressure circuit at the end of the expansion stroke of said piston and for providing communication between said cylinder and said high pressure circuit at the end of the compression stroke of said piston, means utilizing said low pressure circuit for scavenging said cylinder at the end of said expansion stroke,

means utilizing said high pressure circuit for scavenging said cylinder at the end of said compression stroke, a driving connection for said piston, a closed casing surrounding said driving connection and communicating with said low pressure circuit, means including a port arranged in said piston for withdrawing refrigerant from said casing prior to the scavenging of said cylinder at the end of said expansion stroke, and means including a port in said cylinder separate from said above mentioned ports for adding refrigerant to said high pressure circuit prior to the scavenging of said cylinder at the end of the compression stroke of said piston.

14. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low pressure refrigerant circuit and a high pressure refrigerant circuit, a stationary cylinder having high pressure ports communicating with said high pressure circuit and low pressure ports communicating with said low pressure circuit, a second'cylinder reciprocatable between two extreme positions in said stationary cylinder, said second cylinder having high pressure ports communicating with the high pressure ports in said stationary cylinder in one extreme position of said second cylinder and having low pressure ports communicating with the low pressure ports of said stationary cylinder in the other extreme position of said second cylinder, a piston in said second cylinder reciprocatable with respect thereto, means including a driving mechanism for said piston and said second cylinder for compressing refrigerant from said low pressure clr-'- cuit and for expanding refrigerant from said high pressure circuit, means utilizing said low pressure circuit for scavenging expanded refrigerant from said second cylinder in said other extreme position, means utilizing said high pressure circuit for scavenging compressed refrigerant from said cylinder in said one extreme position, and means for maintaining a difference in pressure between said circuits.

15. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction comprising a low-pressure refrigerant circuit and a high pressure refrigerant circuit, a stationary cylinder having high pressure ports communicat-. ing with said high pressure circuit and low pressure ports communicating with said low pressure circuit, a second cylinder reciprocatable between two extreme positions in said stationary cylinder, said second cylinder having high pressure ports communicating with the high pressure ports in said stationary cylinder in one extreme position of said second cylinder and having low pressure ports communicating with the low pressure ports of said stationary cylinder in the other extreme position of said second cylinder, a piston in said second cylinder reciprocatable with respect thereto, means including a driving mechanism for said piston and said second cylinder for compressing refrigerant from said low pressure circuit and for expanding" refrigerant from said high pressure circuit, means utilizing said low pressure circuit for scavenging expanded refrigerant from said second cylinder in said other extreme position, means utilizing said high pressure circuit for scavenging compressed refrigerant from said cylinder in said one extreme position, and means including an additional port in said second cylinder communicating with said high pressure circuit and an additionalport; in said piston communicating with said low pressure circuit for pumping refrigerant from said low pressure circult to said high pressure circuit to maintain a difference in pressure between said circuits.

two extreme positions in said stationary cylinder,

said second cylinder having high pressure ports communicating with the high pressure ports in said stationary cylin er in one extreme position of said second cylinder and having low pressure ports communicating with the low pressure ports of said stationary cylinder in-the other extreme position of said second cylinder, a pistonin said second cylinder reciprocatable with respect thereto, meansincluding a driving mechanism for said piston and said second cylinder forcompressing refrigerant from said low pressure circuit and for expanding refrigerant from said high pressure circuit, means utilizing said low pressure circuit for scavenging expanded refrigerant from said second cylinder in said other extreme posit-on, means utilizing said high pressure clrcuitfor scavenging compressed refrigerant from said second cylinder in said one extreme position, and means including a pressure operated port in said piston and a pressure operated port in said second cylinder and utilizing the movement of said piston for maintaining a difference in pressure between said circuits.

'17. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction including a pair of oppositely disposed cylindershaving pistons therein for alternately compressing and expanding refrigerant received from said low pressure refrigerant circuit and said high pressure refrigerant circuit respectively, means providing communication between said cylinders and said low pressure circuit for scavenging expandedgrefrigerant from said cylinders, means providing communication between said cylinders and said high pressure circuit for scavenging compressed refrigerant from said cylinders, a driving mechanism for said pistons arranged therebetween, a casing enclosing said driving mechanism and communicating with said low pressure circuit, and means including ports in said cylinders for pumping refrigerant from said casing to said high pressure circuit to maintain a difference in pressure between said circuits.

18. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction including a pair of oppositely disposed cylinders, a pair of pistons arranged in said cylinders and reciprocatable relatively thereto, and means including a driving mechanism arranged between said cylinders for alternately compressing and expanding refrigerant in said cylinders, means providing communication between said cylinders and said low pressure circuit for scavenging expanded refrigerant from said cylinders, means providing communication between said cylinders and said high pressure circuit for scavening compressed refrigerant from said cylinders, a casing enclosing said driving mechanism and communicating with said low pressure circuit, and means separate from said scavenging means for pumping refrigerant from said casing to said high pressure circuit to maintain a diflerence in pressure between said circuits.

19. A refrigerating machine of the type utiaos'aoae lizing a gaseous refrigerant without liquefaction including a pair of cylinders spaced apart and arranged in alignment, a pair of pistons arranged within said cylinders, means including a driving mechanism arranged between said cylinders and between said pistons for drivingjsaid pistons and said cylinders, said pistons moving in unison in a direction opposite to that of'said cylinders, means including ports in said cylinders registering with said high pressure circuit at the end of the compression strokes of said cylinders for scavenging compressed gas from said cylinders, means including ports in said cylinders registering with said low pressure circuit at the end of the expansion strokes of said pistons for scavenging expanded gas from said cylinders, a sealed casing enclosing said driving mechanism and communi eating with said low pressure circuit, and means including ports in said cylinders in addition to said above mentioned ports for pumping refrigerant from said casing to said high pressure circuit to maintain a difference in pressure between said circuits. i

20: A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction includinga pair of cylinders arranged in alignment,

a pair .of pistons arranged within said cylinders, means including a driving mechanism associated with said pistons and a driving mechanism associated with said cylinders for reciprocating said pistons and said cylinders and for simultaneously displacing them equally in opposite directions, said pistons and said driving mechanism associated therewith having the same mass as said cylinders and said driving mechanism associated therewith so as to balance said mechanism, means including ports in said cylinders registering with said high pressure circuit on the compression strokes of said pistons for scavenging compressed gas from said cylinders, and means including ports in said cylinders registering with said low pressure circuit on the expansion stroke of said pistons for scavenging expanded gas from said cylinders.

21. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction including a pair of cylinders arranged in alignment, a pair of pistons arranged within said cylinders, means including a driving mechanism associated with said pistons and a driving mechanism associated with said cylinders for reciprocating said pistons and said cylinders and for simultaneously displacing them equallyinopposite directions, said pistons and said driving mechanism associated therewith having the same mass as said cylinders and said driving mechanism associated therewith so as to balance said mechanism, means including ports in said cylinders. registering with said high pressure circuit on the compression strokes of said pistons for scavenging compressed gas from said cylinders, means including ports in said cylinders registering with said low pressure circuit on the expansion stroke of said pistons for scavenging expanded gas from said cylinders, a sealed casing enclosing said driving mechanisms and communicating with said low pressure circuit, and means utilizing said pistons for pumping refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

22. A refrigerating machine of the type utilizing a gaseous refrigerant without liquefaction including a pair of cylinders spaced apart and arranged in alignment, a pair of pistons arranged within said cylinders, means including a driving mechanism arranged between said cylinders and a driving mechanism arranged between said pistons for reciprocating said pistons and said cylinders and for simultaneously displacing them equally in opposite directions, said pistons and said driving mechanism arranged therebetween having the same mass as said cylinders and said drivingmechanism arranged therebetween so as to balance said machines, means including ports in said cylinders registering with said high pressure circuit on the compression strokes of said pistons for scavenging compressed gas from said cylinders, and means including ports in said cylinders registering with said low pressure circuit on the expansion stroke of said pistons for scavenging expanded gas from said cylinders.

23. A refrigerating'machine of the type utilizing a gaseous refrigerant without liquefaction including a pair of cylinders spaced apart and arranged in alignment, a pair of pistons arranged within said cylinders, means including a driving mechanism arranged between said cylinders and a driving mechanism arranged between said pistons for reciprocating said pistons and said cylinders and for simultaneously displacing them equally in opposite directions, said pistons and said driving mechanism arranged therebetween having the same mass as said cylinders and said driving mechanism arranged therebetween so as to balance said machine, means including ports in said cylinders registering with said high pressure circuit on the compression strokes of said pistons for scavenging compressed gas from said cylinders, means including ports in said cylinders registering with said low pressure circuit on means for P p ng refrigerant from said low pressure circuit to said high pressure circuit to maintain a difference in pressure between said circuits.

ALEXANDER R. STEVENSON, JR...

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