US2047057A

US2047057A - Refrigerating machine

Info

Publication number: US2047057A
Application number: US756109A
Authority: US
Inventors: Harold W Brown
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1934-12-05
Filing date: 1934-12-05
Publication date: 1936-07-07
Anticipated expiration: 1953-07-07

Description

July 7, 1936. H. w. BROWN -RE'FRIGERATING MACHINE Ihm.

Filed Dec. 5

'fill/lll',

fill] Sw /o Inventor: Harold W Br'ow'n, bg CL:

His Attorney.

Patented July 7V, i936 REFRIGERATING' MACHINE Harold W.Brown, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 5.1934, serial'No. '156,109

7 claims. (ci. isz-13er UNITED STATES PATENT -GFFICE My invention relates to refrigerating machines of the type in which a gaseous refrigerant is compressed, and cooled Without liquefaction, and is then expanded to produce refrigeration.

Refrigerating machines of the type in which a gaseous refrigerant, such as air, is circulated without liquefaction may be constructed utilizing a compressor in which the gaseous refrigerant is compressed at one end of the stroke and ex,-

panded at theu other end, the compressed gas betermed a wattless compressor. The operation of this compressor tends to equalize the pressures and temperatures in the high and low temperature circuits, and a second power compressor is provided for pumping refrigerant from the low pressure circuit to the high pressure circuitin order to maintain the desired pressure diierence.

An object'of my invention is to provide an im-v proved arrangement for actuating or driving a wattless compressor employed in a refrigeratingmachine of the type in which a gaseous refrigerant is circulated without liquefaction.

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

Fora better understanding of my invention, reference may be had to the accompanying draw- 4Q ling, the single iigure of which illustrates diagrammatically a refrigerating machine embodying my invention.

Referring now to the drawing, I have shown a refrigerating machine including a wattless compressor I 0, connected with a high pressure circuit comprising an air or water cooled coil II and a` scavenging .fan I2, and connected with a low pressure circuit comprising a refrigerating coil I3 and a scavenging fan I 4. A'I'he wattless compressor I0 is of the double-acting type and i comprises a body l5 having cylinders I6 and [6a communicating with each other at both ends vthrough clearance spaces I1 and I8. Within the cylinders I8 and IGa arevarranged pistons I9 and I9a,`which are connected by a yoke 20, so that they reciprocate in uniso'n, the yoke moving into the slot 20a when the pistons move to the left. The cylinder I6 is provided with intake ports 2I and 22 communicating with the high pressure circuit, and with an intake port 23 arranged midway between the ports 2l and 22 and communicating with the low pressure circuit. The cylinder Ilia is provided with exhaust ports 2Ia and 22a communicating with the high pressure circuit and with an exhaust port 23a arranged midway between the ports 2 Ia and 22a and communicating with the low pressure circuit. These ports are annular except for the portions of the cylinderv walls left to provide the requisite strength. The pistons I9 and I9@ are provided with passages 24 andl 24a respectively at theI left ends thereof right ends thereof. These passages open at the sides of the pistons and are arranged to register with their respective cylinder ports when the pistons are near the endof their stroke, and thereby provide a` passage from the intakeports in and with passages 25 and 25a respectively at the cylinder I6 through theclearance spaces to the.v

exhaust ports in the cylinder IBa. t l n During operationvof the refrigerating machine shown when the pistons I9 and Isa. are moved .to

their extreme left-hand positions, ythe passages 24 and 24a will providevcommunicationfbetween t i A the clearance space I1 and the high pressure ports.,v

2I and 2 I a, and the passages 25A andq25a will-profvide communication betweenthe clearance space I8 and the low pressure .ports 23fand 23a.- The gas, which has been compressed in the clearance i space I1 by operation of the pistons, will; now; be

driven out through, the port `2Iaby operation of the scavenging fan-I 2, which will force air cooled in the coil II through` theportZIr and. into the clearance space I'I. This Path of the gas in the high pressure circuit is indicated byA arrows. By this scavenging operation the hot compressed gas is displaced by gas cooled in the coil II at subt low pressure circuit is indicated by arrows. The

by cooler gas, a greater weight of gas is taken from the high pressure circuit than is added thereto, and a greater weight of gas is added to the low pressure circuit than is taken therefrom during the scavenging operation. In order to overcome this eilect and prevent the gradual equalization of the pressures in the high and low pressure circuits, a compressor 26 is provided to pump gas from a connection 21 on the warm side of the coil I3 of the low pressure circuit to a connection 28 on the warm side of the coil II of the high pressure circuit. This compressor is hereafter termed the power compressor.

In the operation of the compressor I0 the pistons I9 and I9a reciprocate. The gas is compressed at one end of the pistons, expanded at the other end thereof, and the pressures in the low and high pressure circuits are maintained substantially constant, so that the net work done on the gas is zero. -The power input to the wattless compressor I Il, therefore, need supply only the friction losses in the compressor in order to keep the pistons in operation. It is evident that the pistons will have a natural period of oscillation under the action of the gas within the cylinder somewhat like that of a spring, there being a differential of zero pressure between the ends of the pistons at the middle of the stroke. The variation from the simple harmonic motion, such as that of an oscillating spring is due to the fact that the pressure does not change during the opening of the ports at the ends of the stroke,

and since the ports are open for an appreciable time the restoring force is constant for this time vand does not act to produce simple harmonic motion.

In accordance with my invention I avoid the necessity ofvproviding a separate driving device for moving the pistons of the wattless compressor III. I accomplish this object by increasing the capacity of the power compressor 26 above that necessary to maintain a balance between the low pressure and high pressure circuits, by an amount suiilcient to supply the friction losses within the wattless compressor. Furthermore, since the pistons of the wattless compresser normally come to rest in midposition, this arrangement provides for setting the pistons in motion during starting of the machine.

Referring again to the drawing, it will be noted that the pistons I9 and I8a are secured together by the yoke 2li, and are free to oscillate in unison within the cylinders I6 and |60.. These pistons are shown in their mid-positions, which is their normal position when the refrigerating machine is not operating, because the pressures in the clearance spaces I1 and I8 are the same when the pistons are in their mid-position. Obviously it is impossible to start the pistons by application of pressure at the cylinder ports -since the ports are all closed when the pistons are in mid-position. In order to set the pistons in motion upon starting of the refrigerating machine, I provide a conduit 29 having therein a normally closed valve 30 which in its open position provides communication between the high pressure circuit and the clearance space I1 at one end of the compressor, and a conduit 3| having therein a normally closed valve 32 which in its open position provides communication between the low pressure circuit and the clearance space I8 at th other end of the compressor.

In order to set the pistons I9 and I9a in motion, the power compressor 26 is started thereby v When the ports 2| and 2Ia open, this pressure producing a pressure difference between the high and low pressure circuits. When the valves 30 and 32 are opened, the pistons are forced to thel right since the pressure within the space I1 is greater than within the space I8. At the end of 5 the stroke the space I8 is placed in communication with the high pressure circuit through the passages 25 and 25a in the piston and the space I1 is placed in communication with the low pressure circuit through the passages 24 and 24a and further motion of the pistons will be cushioned and arrested. If the valves 30 and 32 are now closed, the space I8 being then open only to the high pressure circuit and the space I1 being open only to the low pressure circuit, the pistons will move back and will continue to oscillate at their natural period provided the friction losses are overcome. I provide an automatic arrangement for operating the valves 30 and 32 only during starting, which will be described 20 later, the valves being closed as soon as the ports open at the end of the first starting stroke.

In order to overcome the friction losses of the compressor during its operation after it is started, and thereby to make it possible for the pistons 25 to oscillate at their natural period, I increase the capacity of the compressor 26 over that which would be necessary to maintain a balance in the system if the wattless compressor were driven by an external device. This increased pressure 30 is then available to force the pistons I9 and I9a to the end of their stroke against friction. During operation of the compressor, when the pistons reach their extreme positions to the left the high pressure ports 2l and 2Ia open and the pressure 3.5 in the space I1 becomes that of the high pressure circuit. The pressure in the space I1 is greater than that produced by thev compressor I0 because of the additional pressure produced by the compressor 26. This additional pressure produced by the compressor 26 while the ports 2| and 2Ia are open, being greater than that necessary to compress the gas on the right end of the pistons in the space I8 is suiilcient to overcome friction and move the pistons to the right until the passages 24 and 24a register with the low pressure ports 23 and 23a respectively. Since additional pressure was necessary to move the pistons against friction to this extreme right position, the pressure within the space I1 is greater than the pressure within the low pressure circuit, and some of the expanded gas will ow into the low pressure circuit to equalize the pressures. On the return stroke to the left there is then less gas in the space I1 than on the expansion stroke, and when the pistons have reached their extreme left position the coinpressed gas within the space I1 will be at a pressure less than that of the high pressure circuit.

will be equalized at the pressure of the high pressure circuit and the foregoing cycle will be repeated, the operation at the two ends of the pistons being the same. It is apparent, therefore, that the compressor I0 will continue to operate 65 as long as a suiilcient differential. of pressure is maintained by operation of the power compressor 26 to supply the friction losses.

In order to obtain quick and reliable starting of the pistons I9 and I9a at the beginning 70 of the operation of the refrigerating machine,

I provide an automatic arrangement for operating the valves 30 and 32 including an electrical control circuit associated with an electric motor 33 or other power device utilized to drive the 75 compressor 26. The electric `motor 33 drives the compressor through a connecting rod 34 and piston rod 35, power being supplied to the motor 33 through

leads

36 and 31 connected toa sluitable source of supply through a switch 38. The valves 30 and 32 are provided with operating arms 39 and springs 40 connected to the arms 39 for biasing the valves to their closed position and with solenoids including movable armatures 4I pivoted to the arms 39 and coils 42 for moving the armatures against the force of the springs 40 to open the valves. 'I'he coils 42 are connected in parallel across the motor leads 36 and 31, a normally open relay 43 being provided in one side of the solenoid circuit. When it is desired to start the compressor I0 the relay 43 is closed against a latch 44, so that when the switch 38 is closed to start the motor 33 the solenoid coils 42 will be energized and will open the valves 30 and 32. When the valves are open the pistons I9 and 19a. will move to the right in the manner described above and the clearance space I1 will be placed in communication with the low pressure circuit of the refrigerating machine through ports 23 and 23a. Since the space l1 is in communication with the high pressure circuit through the conduit 29 and valve 3|), there will be a rush of gas from the space I1 through the passages 24 and 24a. into the low pressure circuit. In order to utilize this rush of gas to close the valves 30 and 32, I provide a contact making check valve 45 in a conduit 46 which connects the scavenging fan I4 and the low pressure the relay 43 will be tripped, thereby deenergizing the coils 42 and closing the valves 30 and 32. When the valves have been closed normal operation of the compressor continues, as long as the compressor 26 is maintained in operation to produce the necessary pressure difference between the high and low pressure circuits.

From the foregoing itis apparent that I have provided a simple and improved arrangement for starting and driving a refrigerating machine of the type in which the gaseous refrigerant is circulated without liquefaction and which employs a wattless compressor.

While I have shown my invention as applied to a particular form of refrigerating machine,

`other applications will readily be apparent to those skilled in the art. I do not, therefore, desire my invention to be limited to the particular embodiment shown and described, and I intend in the accompanying claims to cover all modications within the spirit and scope of my invention.

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

1. A refrigerating machine of the type in which a gaseous refrigerant is circulated without liquefaction including a closed system comprising a high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a wattless compressor having a cylinder communicating with said circuits and a piston freely movable in said cylinder for compressing regrigerant received from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant compressed in said cylinder into said high pressure circuit, scavenging means for forcing refrigerant expanded in said cylinder into said low pressure circuit, and means including a power compressor connecting said circuits for pumping refrigerant from said low pressure circuit to said high pressure circuit and for actuating said piston.

2. A refrigerating machine of the type in in which a gaseous refrigerant is circulated without liquefaction including a closed system comprising a high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a wattless compressor having a cylinder com-y municating with said circuits and a piston freely movable in said cylinder for compressing refrigerant received from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant compressed in said cylinder into said high pressure circuit, scavenging vmeans for forcing refrigerant expanded in said cylinder into said low pressure circuit, means arranged in said high pressure circuit for cooling compressed gas discharged from said cylinder, means utilizing the heat absorbing capacity of the expanded gas discharged from said cylinder for producing refrigeration, and means including a power compressor connecting said circuits for pumping refrigerant from said low pressure circuit to said high pressure circuit and for actuating said piston.

3. A refrigerating machine of the type in which a gaseous refrigerant is circulated without liquefaction including a closed system comprising a high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a Wattless compressor having a cylinder communicating with said circuits and a piston freely movable in said cylinder for compressing refrigerant received from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant compressed in said cylinder into said high pressure circuit, scavenging means for forcing refrigerant expanded in said lcylinder into said low pressure circuit, means including a power compressor connecting said circuits for pumping refrigerant from said low pressure circuit to said high pressure circuit and for actuating .said piston, and means utilizing compressed gas for initially producing motion of said piston to start said wattless compressor.

4. A refrigerating machine of the type in which a gaseous refrigerant is circulated without liquefaction including a closed system comprising a high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a wattless compressor having a cylinder communicating with saidcircuits and a piston freely movable in said cylinder for compressing refrigerant received from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant` circuit for initially producing motion of said piston to start said wattless compressor.

5. A refrigerating machine of the type in which a gaseous refrigerant is circulated without liquefaction including a closed system comprising a high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a wattless compressor having a cylinder communicating with said circuits and a piston freely movable in said cylinder for compressing refrigerant received from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant compressed in said cylinder into said high pressure circuit, scavenging means for forcing refrigerant expanded in said cylinder into said low pressure circuit, means including a power compressor connecting said circuits for pumping refrigerant from said low pressure circuit to said high pressure circuit and for actuating said piston, a conduit connecting said cylinder on one side of said piston with said high pressure circuit, a conduit connecting said cylinder on the other side of said piston with said low pressure circuit, valves in said conduits, means operable upon starting of said compressor for opening said valves and for initially producing motion of said piston to start said Wattless compressor, and means responsive to operation of said piston for closing said valves.

6. A refrigerating machine of the type in which a gaseous refrigerant is circulated without liquefaction including a closed system comprising a high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a wattless compressor having a cylinder communicating with said circuits and a piston freely movable in said cylinder for compressing refrigerant received from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant compressed-in said cylinder into'said high pressure circuit, scavenging means for forcing refrigerant expanded in said cylinder into said low pressure circuit, means ncluding a power 5 compressor connecting said circuits for pumping refrigerant from said low pressure circuit to said high pressure circuit and for actuating said piston, and means dependent upon starting of said power compressor for supplying gas from said 10 high pressure circuit to said cylinder for starting said wattless compressor.

7, A refrigerating machine of the type in which a gaseous refrigerant is circulated Without liquefaction, including a closed system comprising a 15 high pressure refrigerant circuit and a low pressure refrigerant circuit, means including a wattless compressor having a cylinder communicating with said circuits and a piston freely movable in said cylinder for compressing refrigerant received 20 from said low pressure circuit and for expanding refrigerant received from said high pressure circuit, scavenging means for forcing refrigerant compressed in said cylinder into said high pressure circuit, scavenging means for forcing refrigerant 'expanded in said cylinder into said low pressure circuit, means including a power compressor connecting said circuits for pumping re frigerant from said low pressure circuit to said high pressure circuit and for actuating said piston, means dependent upon starting said power compressor for supplying gas from said high pressure circuit to said cylinder for starting said wattless compressor, and means dependent upon the ow of gas in said low pressure circuit for cutting oif the flow of gas from said high pressure circuit to said cylinder through said last mentioned means.

HAROLD w. BRowN.- 4o