US1855754A - Refrigerating system - Google Patents

Description

April 26, 1932. J. DuBRovlN 4REFRIcnszRMIING SYSTEM Filed` Feb. 23, 1928 3 Sheets-Sheet April 26, 1932. J. DuBRovlN REFRIGERATING SYSTEM Filed Feb. 23, 1928 3 Sheets-Sheet 2 (f5/717 DuraV/'f 5% Y /Z April 26, 1932 J. DUBRoviN 1,855,754

REFRIGERATING SYSTEM Filed Feb. 2s, 192s s sheets-sheet s I j' Y 4f l 43 f f 7 .loy l' WM Y l l; 'A ity! Patented Apr. 26, 1932 PATENT OFFICE JOHN DUBRDVIN, F LOGAN SPORT, INDIANA REFRIGEBATING SYSTEM Application filed February23, 1928. Serial No. 258,303.

My invention relates to compression refrigerating systems and in some of its general objects aims to improve the efiiciency of the entire system, to reduce the sizes of the condenser and motor required for a given refrigerating capacity, to reduce the required amount of refrigerant, to eliminate the need of an oil separator, to insure a sensitive temperature control, and to avoid expansion valve troubles.

Compression refrigerating systems employing refrigerants of the general class of sulphur dioxide, ethyl chloride and the like, usually have piping through which the refrigerant passes successively from the compressor through the condenser, the expansion valve (and sometimes through a receiver between the condenser and the expansion valve), through an eyaporator, and then back to the compressor. Such systems commonly have the following objections, which my invention particularly aims to overcome:

(l) In operating such a system in refrigerators designed for households, from onethird to one-half of the total refrigerant usually remains in the condenser during the pe- I riods when the compressor is not running.

Consequently. the condenser must have a correspondingly large liquid storage capacity, or must be supplemented by a liquid-storing receiver, and a correspondingly large amount of refrigerant must be provided. Vhen the compressor again starts ruiming, a heavy motor torque is needed to start against the high pressure due to the presence of liquid in the comparatively Warm condenser, thus requiring a larger size of motor than would other- Wise be ample. My invention aims to overcome these objections by providing a refrigerating system in which the condenser is substantially emptied during each period in which the compressor is not running, and by reducing the pressure of the condenser during each such idle period, thereby greatly reducing the needed size of condenser and likewise reducing the starting torque of the compressor.

(2) The lubricating oil Which accumulates in the condenser along with the liquid refrigerant during the Working of the compressor,

also occupies considerable space in the condenser, thus further increasing the needed size of the condenser. And, since this oil is a poor conductor of heat, its presence greatly reduces the eiiciency of the condenser. While the last mentioned difficulties may be reduced by employing an oilseparator, this in turn involves an increased initial cost, together with the diculty of keeping the needed oil-return valve adjusted and free from clogging. My invention aims to overcome these objections by providing a system in which oil as Well as liquid refrigerant will continually trickle or seep from the condenser to the evaporator While the compressor is running, so that no large amount of oil will accumulate in the condenser, thereby further reducing the required size of the condenser and greatly increasing the eiiiciency of the condenser.

(8) Compression refrigerating systems also commonly employ an expansion valve of a needle valve type, which is ditiicult to maintain in proper adjustment and apt to clog, and which varies greatly in effectiveness With its wear, thereby impairing the eiciency of the system and often causing a chattering ofthe valve. My invention aims to overcome these diificulties by providing a valve which never closes entirely and hence eliminates the likelihood of clogging, which requires no close tting tip adapted to Wear unduly, and which will require no adjusting. Furthermore, my inventionprovides a system in Which the valve affords an unusually large passage when opened, so that the liquid refrigerant can quickly iiush oii'` any particles of impurities adhering to the condenser piping, the valve portions, or other interior parts.

(4) In the usual compression refrigerating systems, a bursting (or explosion) of the condenser piping sometimes occurs, owing to an excessive increase of pressure in the condenser in case the system becomes deranged. My invention aims to overcome this by providing a valv'e arrangement which will automatically relieve such an excessive pressure in the condenser by freely connecting the condenser to the evaporator.

Furthermore, my invention provides simple means for simultaneously and positively moving the liquid control valve to its liquidthrottling disposition when the compressor is started, and for keeping it so disposed 'until the pressures in the evaporator is substantially reduced and the compressor is halted. Then the throttling of liquid by the valve is greatly increased and the pressures in the system are substantially equalized so as to reduce the back pressure against which the compressor must be started in the usual compression type refrigerating systems. My invention also provides a system in which the entire control means are easily manufactured, durable and not likely to get out of order, and one in which neither a spring nor a diaphragm will be required in the liquid control valve.

Still further and also more detailed objects will appear from the following specification and from the accompanying drawings, in which ig. 1 is asomewhat diagrammatic view of a compression system embodying my invention and including a liquid control valve magnetically actuated in one direction, with the compressor shown in central and vertical section.

Fig. 2 is an enlarged central and longitudinal section through the liquid control valve of Fig. 1, showing the plunger in the throttling disposition in which it is electromagnetically retained as long as the compressor is running.

Fig. 3 is a central and vertical section through lower end portions of the same valve, showing the position of the lower end of the plunger when the plunger hasbeen lifted by the pressure of liquid .refrigerant after the compressor was halted.

Fig. 4 is a horizontal section taken along the line 4-4 of Fig. 3, showing the slots in the plunger which afford liquid passages.

Flg. 5 is a partially sectioned enlargement of the current-controlling valve of Fig. 1.

Fig. 6 is a diagrammatic view of another compression system embodying my invention, namely one in which a single diaphragm-actuated valve stem actuates an electric switch for controlling the motor-driven compressor, and also mechanically governs the liquid 'control valve.

Fig. 7 is an enlarged central and vertical section through the valve of Fig. 6.

Fig. 8 is a horizontal section taken along the line 8 8 of Fig. 7.

Fig. 9 is a diagrammatic view of another embodiment of my invention, namely one in which the liquid-control valve is mechanically responsive to the starting and stopping of the compressor.

Fig. 10-is an enlarged central and vertical section through the liquid control valve of Fig. 9.

Fig.k 11 is an enlarged side elevation of the tip of the liquid control valve member of Fig. 7.

Fig. 12 is a partially sectioned enlargement of the medial portion of the movable valve member of the valve of Fig. 10.

Referring first to the embodiment of Figs. 1 to 5 inclusive, Fig. 1 shows a compressor including a piston 1 connected by a pitman 2 and a crank 3 to the shaft 4 of an electric motor 5.

An intake pipe 6 leads to the crank casing 7 of the compressor, while an outlet pipe 8 connects the compression chamber 9 of the compressor with the condenser 10. The discharge end of the condenser is connected to the top of the evaporator 11 through a liquid control valve and a connecting pipe 12, and the intake pipe 6 leads from this evaporator to the compressor to complete the circuit for the refrigerant.

The liquid control valve includes a tubular and desirably upright shell 13 spaced radially from a plunger-guiding tube 14 by portions of a lower head 15 and an upper head 16, and a solenoid coil of wire 17 is disposed in the annular space between the said tube and shell. The valve bottom 15 has a threaded inlet 15B to which the discharge end of the condenser 10 is connected and has its vertical bore reduced in diameter at its upper end, desirably by inserting a bushing 18 (Fig. 3) having a relatively minute bore, and the upper end of this nipple is above the bottom of the solenoid coil 17. The upper end of the guide tube 14 carries a nipple 19 for connecting it to the pipe 12 which leads to the evaporator, and this nipple has its lower end spaced from the top of the valve bottom by a distance considerably greater than the length of a soft iron plunger 2O which is freely slidable in the guide tube 14. This plunger 20 desirably has longitudinal slots 21 extending radially inward from its periphery and also has a bottom recess 22 opening into these slots 21, while the lower end of the nipple 19 has transverse slots 23 which will connect the slots 21 with the bore of the nipple 19 when the plunger is raised so that its upper end abut-s against the bottom of the nipple.

The solenoid 17 is connected to the motor circuit 24 and to an oscillating mercury switch 25 which simultaneously controls the flow of current to both the motor and the solenoid of the liquid control valve, for which purpose the solenoid is here shown as connected in series with the motor 5. although the arrangement of the circuit connections is not material. The switch 25 is pivoted on a riser 26 mounted on the cover 27 of a diaphragm casing 28, through a lever 29 which has an approximately horizontal arm provided with an approximately vertical slot 30. Extending downwardly into the casing 28 through the cover 27 is a thrust stem 31 carrying at its upper end a transverse pin 32 which moves in the slot 30, while the lower end of the thrust stem 31 carries a disk 33. Connecting this disk 33 with the cover 27 is a bellows-like tubular member 34 of sufficient flexibility to be expanded or contracted in length by differences in pressure between the interior and exterior of this member, which bellows member is sealed at its ends respectively to the disk 33 and the cover 27. A compression spring 35 within the said bellows member is interposed between the disk 33 and the bottom of a nipple 36 through which the thrust stem 31 loosely extends, and this nipple is threadedly connected tol the cover 27 to permit an adjusting of the pressure of the spring. A pressure pipe 37 leads from the top of the evaporator 11 to the bottom of the casing 28, so that the interior portion of the casing surrounding the bellows member 35 and below the disk 33 is at the vapor pressure in the evaporator, while the interior of the bellows member is subjected to the pressure of the outer air. The movement permitted to the stem pin 32 by the length of the slot 30 in the lever which carries the mercury switch afs fords lost motion to permit a quick snapping action of the switch in response-to corresponding pressure increases or decreases in the evaporator, so that the mechanism as just described simultaneously controls the How of current to the motor and to the solenoid of the liquid control valve, in response to the pressure variations within the evaporator for which the spring 35 was adjusted by the setting of the nipple 36.

With my refrigerating system thus arranged. current is only supplied to the solenoid 17 while the compressor isoperating, thus holding the plunger during the operation of the compressor in the position shown in Fig. 2, in which portion liquid refrigerant can only seep slowly through passages restricted in size by the diameter of the valve bottom bore18. Thus disposed, the throttling position of the plunger permits both liquid refrigerant and oil to pass continuously but at a slow rate from the"condenscr to the evaporator, as the action of the solenoid holds the plunger in its said position against the pressure due to the operation of the co1npressor, and the pressure in the condenser and the evaporator tend to equalize while the compressor is running. This continuous flow through lthe valve avoids the accumulation of both liquefied refrigerant and oil 'in the condenser, and continues until the suction of the compressor through the intake pipe fi has reduced the vapor pressure in the condenser below that for which the spring 35 associated with the switch was adjusted.

lVhen this critical minimum pressure is reached, the spring snaps the switch to its below it, presses liquid refrigerant and oil (if present) up through the bottom bore 18 of the liquid control valve and against the bottom of the plunger, thereby forcing the plunger up against the stop nipple 19 in the top of the casing of this valve. This effectively opens the valve to a greater extent and permits a more rapid flow of the liquid refrigerant into the evaporator, so that the latter will house by far the greater part of the refrigerant by the time the vapor pressure in the upper portion of the condenser is substantially equal to that in the evaporator. The approach to pressure equalization may vary somewhat with the weight of the plunger and with the arrangement of the pipes leading to and from the casing of the liquid valve, but such variations are relatively immaterial.

When this pressure equalization is reached, the plunger gradually sinks to its downward or liquid-throttling position and gravity holds it there while the withdrawal of heat from the evaporator as for example by the food chamber in which the evaporator is disposed) has raised the vapor pressure in the evaporator to the point where the bellows member 34 is sufficiently collapsed to move the switch back to its on position of Figs. 1 and 3. The closing of the circuit through the motor then starts thev compressor again, while the simultaneous closing of the circuit through the solenoid causes the latter to exert its downward pull on the plunger 2O of the liquid control valve. Since this plunger had already dropped by gravity upon the valve bottom before this occurs` there can be no chattering. The suction of the compressor then again draws refrigerant vapor out of the vaporizer, while the pressure of freshly compressed vapor fed to the condenser slowly forced more liquefied refrigerant through the valve into the evaporator.

Owing to the relatively wide opening of the valve when the plunger was raised and to the above described previous equalizing of pressure. relatively little liquid refrigerant (or none at all) was left in the condenser when the compressor is again started. and the pressure of vapor in the compression chamber of the compressor and in the upper portion of the condenser had also been greatly reduced during the idle period of the compressor, as this vapor expanded while forcing liquid refrigerant out of the condenser into the evaporator. Consequently, the initial strokes of the compressor encounter very little back pressure, thus reducing the starting torque required in the motor and thereby permitting the use of a lower poweredmotor for a given size of compressor. So also, the relatively small amount of warmed liquid which was left in the condenser produces only a rather negligible effect on the evaporator when forced into the latter.

When my refrigerator is thus operating, the condenser is cleared of lubricant during each idle period of the compressor, and the absence of the usually large amount of oil in the condenser greatly increases the heat trans- Lfer through the condenser, thereby increaslng the efficiency of the latter. By deliberately permitting seepage from the condenser to the evaporator through the valve while the compressor is running, I avoid the need of a needle valve member, or other tightly seating movable valve member, and can employ an unusually durable valve arrangement in which a hard and acid-proof material may be used both for the valve seat and the plunge1' bottom. Since both the valve seat and the valve bore are amply flushed whenever the plunger 1s ralsed, any particles of impuritles are then washed away, thereby preventing.

all clogging and insuring the desired seepage flow. Since the radial slots 21 in the plunger also deter eddy currents, my electromagnetically operating valve can readily be used on alternating current as well as direct current circuits, and particularly so, since this valve is continuously cooled by the refrigerant which passes around the solenoid core (plunger) and through the slots in the latter.

The pressure-controlled switch also can be of a quite simple and rugged construction,

y as shown for example in Fig. 5 and with the major portion of the refrigerant housed by the evaporator, the desired approximate uniformity of the temperature around the evaporator can be obtained with the oppositely directed movements of the switch-actuating stem 31 responsive to considerable differl ences of the vapor pressure in the evaporator.

Consequently, no highly delicate adjustment or readjustment of the spring-pressure regulating nipple 36 is required, which is the only adjustable portion of the entire refrigerating system shown in Fig. 1. To prevent liquid refrigerant from entering the pipes 6 and 37, these should lead to the vapor space at the top of the evaporator, but the arrangement shown diagrammatically in Fig. 1 may otherwise be modified in many ways.

Moreover, while I have heretofore described my refrigerating system as including an electromagnetic valve, I do not wish to be limited in this respect, as other liquid control valves may be employed to good advantage if also operated in substantial unison with the starting and the stopping of the compressor.

For example, Fig. 6 shows another embodiment of my invention, in which the switchactuating stem 41 extends downward into a valve casing 42 through which the liquid refrigerant iows from the condenser 10 through a pipe 37 intb the evaporator 11. In this case, a generally horizontal diaphragm 43 has its edge portion clamped between the mouth of the valve casing 42 and the cover 44. The

valve stern 41 extends vertically through the center of the diaphragm and is sealed to the latter (as by soldering), and the lower` position of the stern extends through one arm 45 of a bell-crank lever which is held in pivoting engagement with a notched bracket 46 (mounted in the casing) by a spring 50. The other lever arm 47 carries a valve tip 48 shaped so that it can throttle the inlet to the casing from the pipe 10, and the stem has enlargements 51 and 52 disposed respectively for engaging upper and lower faces of the lever arm 45 but spaced to permit lost motion so that the diaphragm 43 can flex from its upwardly bowed disposition of Fig. 7 to the downwardly bowed form shown in dotted lines.

When moved to the latter position by the snapping of the spring 50, the bottom of the enlargement 52 is still above the bottom of the casing, so as to allow the flow of liquid into the pipe 37; and in the same (dotted line) position the lever tip 41 is freely spaced from the adjacent wall of the casing to permit liquid to enter from the pipe 10. lVhen the lever is in its raised (full line) position of Fig. 7, the lever tip 48 seats in the inlet from the pipe 10, the entrance of the liquid is then throttled, as it can only iow through a suitable passage provided at this tip, such asthe slot 54 of Fig. 11. Thus arranged, a rise of vapor pressure in the evaporator 11 to a point suflicient for snapping the diaphragm 43 upwardly will raise the diaphragm, thereby causing the valve-tip 41 of the lever to throttle the flow of liquid from the condenser through the valve casing to the evaporator, while the same movement of the diaphragm rocks the switch 25 to its on position and starts the driving of the compressor. Likewise, a drop of pressure in the evaporator (and hence in the casing 42), to the point where the pressure of the outer air will flex the diaphragm downwardly, will rock the lever to the dotted position of Fig. 7. This movementhalts the compressor and permits the free How of liquid refrigerant from the condenser to the evaporator to flush the condenser and the valve casing, also permitting a substantial emptying of the condenser and an equalizing of the pressures in the condenser and evaporator.

Fig. 9 shows still another embodiment of my invention, namely one in which the switch 25 is actuated in response to the vapor pressure in the evaporator, after the manner of the switches in Figs. 1 and 6, but the switch is electrically connected only to the electric motor 5, so as to start and stop the latter in response to vapor pressure variations in the evaporator. The crank-shaft 4 of the compressor has a bushing 55 fastened to it by a set screw 56, while another bushing 57 is slidably supported on the shaft and extends beyond the end of the shaft, as shown in Fig. 10. This slidable bushing 57 has a projecting stem 58 disposed for exerting an inward thrust on the bottom 59 of a bellows member 60 which has its other end sealed to the perforated cover 61 of a stationary casing 62, which casing is supported (by means not shown in the drawings) for alining the casing axially with the shaft. A ball 63 is preferably interposed between the tip of the stem 58 and the bottom 59 of the bellows member to reduce friction between these parts. The bottom of the casing 62 has an outwardly extending tube 64 through which the interior of the casing is connected to the condenser 10, and this connection is controlled by a. valve member 65 which engages the bottom 59 of the bellows member, and which valve member is continually pressed against the said bottom by a spring 66, and the interior of the casing is also connected to the evaporator 11, as shown in Fig. 9. The shaft bushings 55 and 57 are connected by normally straight and resilient members 88, each of which carries aweight 59.

When the compressor is not running, these resilient members 88 hold the slidable bushing 57 in the osition shown in full lines in Fig. 10, there y forcing the bottom of the bellows member, together with the valve member 65 away from the end of the shaft 4 and holding the closure portion of the valve away from a seat 67 in the tube 64, thereby affording a full open connection from the' condenser to the evaporator. As soon as compressor starts running, the rotation of the shaft 4 and of the resilient members 58 causes the Weights 59 to separate by centrifugal action, thereby flexing these members 88 outwardly and drawing the slidable bushing 57 away from the valve and diaphragm casing 62. This permits the spring 66 to seat the valve member 65, but slots 68 in the head of this valve member (shown in Fig. 12) still maintain a throttled connection to permit a seepage of liquid refrigerant and oil from the condenser to the evaporator.

In each of the illustrated embodiments, the starting and stopping of the compressor is responsive to differences in the vapor pressure within the evaporator, and the liquid control valve is held in a position as long as the compressor is running but is released and moved to a full open position when the cornpressor is halted. Consequently, neither liquid refrigerant or oil can accumulate to any considerable extent in the condenser, and by far the greater part of the refrigerant is continuously stored in the evaporator. Since the connection between the condenser and the evaporator is never entirely shut of, no perfect fitting of the valve parts is required (as in the expansion valves now commonly employed) and the wear on these parts will not materially affect the efficiency of the system. Moreover, the entire control is in response to pressure variations in the evaporator, which is commonly disposed Where the refrigerating effect is to be utilized (as for example in the food chamber of a household electric refrigerator), so that no separate thermostatic switch is required.

However, while I have described my invention in embodiments including a reciprocating piston type of compressor, I do not Wish to be limited to this or other details of the construction and arrangement here disclosed, since many changes may obviously be made without departing either from the spirit of my invention or from the appended claims.

With control mechanisms of thegeneral type of those shown in Fig. 2 and Fig. 7, I also secure the added advantage that such a mechanism serves as a safety valve in case a derangement of the system permits the pressure in the condenser to become excessively high. In such a case, the high pressure would overbalance the electromagnetic pull on the valve member of Fig. 2 and would likewise tend to move the lever of Fig. 7, so as to open the valve and relieve the pressure by freely connecting the condenser to the evaporator.

I claim as my invention.:

1. A refrigerating system including a compressor, condenser and evaporator successively and continuously connected in series with each other, means for driving the compressor; and automatic control means for throttling the connection between the condenser and the evaporator when the compressor is in operation, and for widely opening the said connection when the compressor is halted.

2. A refrigerating system including a compressor, condenser and evaporator successively and continuously connected in series with each other, means for driving the compressor; a throttling valve disposed for controlling the connection between the condenser and the evaporator, and conjointly acting means responsive to the pressure in the evaporator for controlling the actuation of the com-- pressor and controlling the valve.

3. A refrigerating system including a compressor, condenser and evaporator successively and continuously connected in series` with each other; an electric motor driving the compressor; an electric circuit connected to the motor; and means responsive to the vaporpressure in the evaporator for controlling the electric circuit and controlling the connection between the condenser and the evaporator, the said means being arranged for maintaining a seepage connection between the condenser and the evaporator as long as the circuit to the motor is closed.

4. A refrigerating system as per claim 3, in which the said means include a switch in the electric circuit and an electromagnetic valve also controlled by the switch and controlling the said connection.

5. A refrigerating system including a compressor, condenser and evaporator successively in series with each other; an electric motor driving the compressor; a valve casing interposed between the condenser and the evaporator; a valve member movable in the casing and arrangedto permit a seepage of refrigerant from the condenser to the evaporator when the valve member is in one position, and to permit a relatively free passage of refrigerant from the condenser to the evaporator when the movable valve member is in a second position electromagnetic means arranged for holding the movable valve member in its first named position, and means responsive to the pressure in the evaporator for controlling both the operation of the motor and the electromagnetic means.

6. An assembly of refrigerating system parts as per claim 5, in which the valve member is movable in one direction by the magnetic fiux in the coil and in the opposite direction by the pressure of refrigerant flowing from the condenser to the evaporator.

7. For interposition between the condenser and evaporator of a compression refrigerating system, a valve casing; a valve member slidable in the casing to control the passage of refrigerant through the casing while continuously permitting refrigerant to flow from the condenser to the evaporator, the valve member havinga portion of magnetizable material; a wire coil coaxial with and surrounding a portion of the valve member, an electric circuit connected to the coil, and means responsive to the pressure in the evaporator for controlling the said circuit.

8. A refrigerating system including a compressor, condenser, valve and evaporator successively in series with each other, the valve including a member, movable between two positions in which it respectively affords a mere seepage of refrigerant and a voluminous passage of refrigerant through it; means responsive to an increase of pressure in the evaporator above a predetermined minimum for holding the movable valve member in its seepage affording position against the pressure of refrigerant in the condenser; and means responsive to a decrease of pressure in the evaporator below the said minimum for `releasing the said holding of the valve member in its seepage affording position, the said member being then movable to its voluminous passage-aifording position by the pressure of refrigerant in the condenser.

9. Means for controlling the flow of refrigerant from the condenser to theY evaporator of a refrigerating system, comprising a valvel casing interposed between the condenser and the evaporator, a valve member movable in the casing from a first position in which it permits a voluminous passage of refrigerant to a second and eXtreme position in which it permits only a relatively restricted passage; connections from the casing to the condenser and the evaporator, the connections being such that the flow refrigerant from thecondenser through the casing will tend to move the said valve member towards its said first position, and means responsive to a predetermined increase in the refrigerant vapor pressure in the evaporator for holding the said valve member in its said first position.

10. Control means as per claim 9, in which the said pressure-responsive means are also arranged for moving the said valve member from its first to its second named position when the vapor pressure in the evaporator decreases to less than a predetermined minimum.

11. A compression refrigerating system including an intermittently actuated compressor having a compression chamber, an evaporator, and a condenser interposed between the compression chamber and the evaporator and connected to both of the latter by continuously open connections; and cont-rol means including a single mechanism responsive to pressure changes in the system for controlling the actuation of the compressor and for effecting a reduction of pressure in the compression chamber and the condenser before each restarting of the compressor.

1Q. The combination with the compressor, condenser and the evaporator of a compression refrigerating system, of a valve casing interposed between the condenser and the evaporator, a valve member movable in the casing and arranged for continuously allowing refrigerant to flow from the condenser to the evaporator, the valve member being arranged to permit a mere seepage of refrigerant through the casing when the valve member is in one position, and permitting a full flow of refrigerant from the condenser to the evaporator when in a second position; valve-holding means responsive to the actuation of the compressor for moving the valve to and holding the valve in its said second position; the movable valve member being movable from its said seepage permitting position toward its said second position by the pressure of liquid in the condenser when the said valve-holding means are inoperative.

Signed at Chicago 1928.

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