US 2331264 A
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Description (OCR text may contain errors)
Oct, 5, 1943.
F. Y. CARTER REFRIGERATING SYSTEM Filed May 17. 1940 #Mmmm Patented Oct. 5, 1943 REFRIGERATING SYSTEM Franklyn Y. Carter, Detroit. Mich.. assignor to Detroit Lubricator Company, Detroit, Mich., a
corporation of Michigan Application May 17, 1940, Serial No'. 335,846
This invention relates generally to refrigerating systems and more particularly to systems using a capillary tube feeding device.
One object of the invention is to increase the eiliciency of a refrigerating unit by providing means for preventing the passage of high pressure refrigerant vapor into the-evaporator during off periods of the compressor.
Another object is to provide an automatic means for operating the iiow preventing means.
Another object is to utilize the unloader of the compressor as the automatic means.
The invention consists in the improved construction and combination of parts, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.
Inl/the accompanying drawing, to be taken as a part of this specification, I have fully and clearly illustrated a preferred embodiment of my invention in which drawing:
Figure 1 is a diagrammatic view of a refrigerating system including the control valve which is shown in central vertical section,
Fig. 2 is an enlarged detail view partly in section and showing onelform of compressor unloading means, and
Fig. 3 is a partial View in central vertical section of a modified form of the valve member.
Referring to the drawing by characters of reference the numeral I designates generally a valve means having an outlet 2 and an inlet 3. The outlet 2 is connected to the inlet of an evaporator 4 which may be of any desired type and which is shown as a continuous coil type having its outlet connected by means of a conduit 5 to the inlet 6 of a compressor 'I having unloading means for equalizing the inlet and outlet pressures upon stopping of the compressor. This pressure equalizing or unloading means may be any of the conventional devices for accomplishing this purpose. In some rotary compressors this means is inherent in that there is suiicient clearance for leakage back through the vanes or blades to equalize quickly the outlet and inlet pressures on stopping of the compressor. In other compressor types or constructions additional means must be employed for pressure equalization, such for example as a solenoid valve which is energized to closed position when the compressor motor is energized. The compressor 'I has its outlet connected by means of a conduit 8 to the inlet of a condenser or radiator 9. With a solenoid valve type of unloader, the inlet 6 is connected to the outlet conduit 8 by a bypass pipe 8a in Whichis intercalated a normally open, when deenergized, solenoid valve 8b having its coil or winding connected in parallel or multiple with the compressor motor I I by lead wires 8C, 8d connected respectively to the lead wires I5, I6 on the motor side of the switch I3. The condenser outlet is connected to the inlet 3 of the valve means I by a capillary tube refrigerant feed device Ill which regulates the ow of the liquid refrigerant to the evaporator in the well known manner of the prior art. The compressor l is driven by an electric motor II as by means of a belt I2. Operation of the motor II is controlled by means of an automatic switch I3 operated by a temperature sensitive bulb means I4 secured to the evaporator adjacent its outlet or placed wherever it is desired to control the temperature. The switch controls the circuit from the source of electrical supply through lead Wires I5 and I5 and upon closure of the switch I3 the motor II is started to drive the compressor 1.
The valve means I comprises a tubular member I'I having a central longitudinal aperture therethrough. The lower end portion of the member I'I is the inlet 3 and is adapted to receive one end of the capillary tube device I0 which substantially ts the central aperture and is held in fluid-tight relationship therewith as by means' of solder. The member Il extends through a central aperture in the bottom wall I8 of a cupshaped casing member I9 and an outwardly extending shoulder 2U which is located substantially midway between the ends of the member I7 is positioned against and soldered to the wall I8. The upper end portion is within the interior ol the casing I9 and has at its end surface a valve port 22 which is controlled by means of a valve member 23. The member 23 has a polygonal extending portion 23a which is reciprocal within and is guidedby the longitudinal aperture of the member Il thereby to maintain the valve member 23 in correct relationship to the port 22. The polygonal faces cooperate with the wall of the aperture of member I1 to provide Ilow pas sageways for flow of fluid refrigerant from the' inlet 3 to the valve port 22. Packing or seating material 24 is carried in an annular recess in the lower end wall of the member 23 so that upon closure of the valve port 22 by the member 23 the material 24 engages the upper end wall of the member I'I and prevents ow of fluid through the port 22. A helical coil spring 25 is positioned concentric with the member Il and has its lower end portion engaging the bottom wall I8. The upper end portion of the spring 25 engages an outwardly ext-ending flange 28 of the valve member 23 and due to the expanding force. of the spring 25, the valve member 23 is urged toward open position.
Adjacent to but spaced from its top end, the member I9 has a shoulder 21 against which a diaphragm member 28 is positioned. The member 28 acts to seal the open end of the casing member I9 to form a chamber 28a and also acts to position the valve member 23 relative to the port 22. The valve member 23 is constructed with a flat top surface portion which is substantially in the plane of the shoulder 21 when the valve member 23 is seated. The outlet 2 opens throughthe side wall of the member I9 and forms a fluid flow path from the chamber 28a to the evaporator 4.
A cap member 29 .has its peripheral portion held against the peripheral portion of the diaphragm member 28 and has its central portion spaced from the central portion of the diaphragm member 28 and cooperates therewith to form a pressure sensitive eXpansible-contractible chamber 3U. The end portions of the side walls of member I9, which extend beyond the shoulder 21, are bent inwardly to clamp the peripheral portion of cap member 29 and diaphragm member 28 tightly against the shoulder 21.- As an additional means of securing the members together in fluid-tight relation, solder is placed in the channel formed at the intersection of the Vmembers 28, 29 and I9.
The cap member 29 has a central aperture therethrough in which one end of a capillary tube 3| is sealed in fluid-tight relation, as by solder. The other end of the tube 3| is secured to the inlet 6 of the compressor 1 on the compressor side of a check valve 32 which valve is positioned within inlet 6 and is operable to prevent flow of uid from the compressor 'I to the evaporator 4.
The valve means I of Fig. 2 differs from the valve means I chiefly by the construction of the tubular member I1' and the valve member 23. The member I1' comprises a tubular member having a larger diameter portion and a smaller diameter portion forming at their intersection a shoulder 29 which seats against the lower or bottom wall of the casing I9 and is held in fluidtight relation therewith as by solder. The tubular member I1' has its larger diameter portion external of the casing I9 and has its longitudinal aperture internally screw-threaded for reception of a seat member 33 which has a central longitudinally extending aperture therethrough, the outer.end of which receives the outlet end of the capillary tube means ID. Solder is utilized around the joint between the means I and member 33 and in the joint between the member 33 and lower end of the member I1 to prevent any leakage of fluid from the interior of the member I1 to atmosphere. The inner end of the seat member 33 forms a valve seat which is controlled by means of a valve member-23. The valve member 23 has a head portion 34 which engages the underside of the diaphragm member 28 and has a polygonal portion 35 reciprocal within the upper end of the central aperture of member I1. The lower end portion of the polygonal portion 35is conical in shape and cooperates with the aperture through the seat member 33 to control flow of fluid` therethrough. The head portion 34 is urged upward into engagement with the diaphragm member 28 by a spring 36 which has one end engageable with the portion 34 and has lts other end engaging the lower end wall of the member I9.
Because the valve means I is intended to be primarily operative during the oil" periods of a normally cycling capillary tube rel'rigerating system, the operation of the system in which the valve means I is incorporated can best be described by referring to the system when it is already maintaining the evaporator between the given predetermined temperature limits as determined by the bulb means I4. The switch I3, controlled by the bulb means I4, is of the type for operating a refrigerating system according to temperature change and which is well known to those skilled in the art. The evaporator temperature is assumed to be midway between the said predetermined temperature limits with the compressor 1 being operated by the motor II through the belt I2. High pressure gaseous refrigerant is being discharged by the compressor i through conduit 8 into the condenser 9 where heat is radiated therefrom to the ambient air so that the gaseous refrigerant can condense to liquid form so that substantially only liquid refrigerant flows from the capillary tube feeding means I0 to the valve means I and the evaporator 4. The exact place of complete condensation of the refrigerant to liquid phase varies somewhat depending upon the pressure maintained in the evaporator 4 and the ambient temperature surrounding the condenser 9 which is reflected as refrigerant pressure within the condenser 9. If the ambient temperature is high the pressure drop across the capillary tube means I0 is great and more refrigerant can flow therethrough so that the point of complete liquid phase may be within the means I or in extreme conditions may never occur. With low ambient temperatures the point of complete liquid phase may be within the condenser 9 because the refrigerant pressure therein is low and the pressure drop across the capillary means IIl is correspondingly low and the liquid does not flow therethrough as rapidly. By the backing up into the condenser 9 of the liquid refrigerant, the radiating surface thereof is made smaller with an effective increase in refrigerant pressure therein so that the rate of flow through capillary means I0 equals the rate of inflow to the condenser 9 by the compressor 1. The ideal location of the point of complete liquid phase is intermediate the capillary tube means IG and condenser 9 as this gives most economical operation.
The evaporating refrigerant in the evaporator 4 is removed by the compressor 1 and discharged to condenser 9, the solenoid valve 8b, if employed, being energized and closed. This lowers the temperature of the evaporator 4. When theminimum predetermined temperature of evaporator 4 is reached, the switch I3 controlled by bulb means I4, will open the circuit through lead wires I5, I6 to the motor II to stop operation of the compressor 1. Immediately upon stopping of the compressor 1, due to the unloader means included therein, pressure from the condenser 9 finds its way back through the blade clearance or the opened bypass conduit of the compressor 1 to the inlet 6 where a check valve 32 is positioned which closes and prevents the passage or flow of refrigerant from compressor 1 through conduit 5 to evaporator 4. The capillary tube 3l is, however. open to the compressor 1 between it and the check valve 32 positioned in inlet 6 and the rcfrigerant pressure is transmitted thereby and therethrough to the pressure chamber 30 and acts on the top side face of the diaphragm member 28 to compress the spring 25 and to force the valve member 23 against; the port 22 to prevent further flow of refrigerant from the capillary means I to the evaporator 4. The lower side face of the diaphragm member 28 is subjected to the pressures within the chamber 28a and which due to its constant communication with the evaporator 4 is always at evaporator pressure which is a relatively low pressure so that the high pressure in chamber 30 can seat the valve member 23.
Under the prior art systems and those omitting the valve means I, the capillary tube means I0 continues to supply liquid refrigerant to the evaporator 4 after the compressor 'I has been stopped. This is quite satisfactory as far as operation is concerned, but soon the liquid in means I0 and condenser 9 is all gone and only hot, high pressure refrigerant vapor remains. When this enters the evaporator 4, the gaseous refrigerant is condensed therein with a consequent rise in temperature of evaporator 4 due to the increased heat content thereof. This means that the temperature sensitive switch will again call for compressor operation sooner than it otherwise would. Before any useful refrigeration Work can be done the by-passed vapor or gas must be again pumped by the compressor 'I to4 the condenser 9 to raise the pressure therein to a suitably high point so that the heat of vaporization of the refrigerant may be radiated and thrown off to the medium surrounding condenser 9. A motor driven fan may be utilized to increase the radiating effect of the condenser 9 if desired and which fan may be controlled in Synchronism with motor II or the fan may even be driven by the motor I I. By the inclusion of the valve means I, flow through the capillary tube means I0 subsequent to stopping of the compressor 9 is prevented so that the uncondensed high pressure gaseous refrigerant within condenser 9 is kept from flowing into the evaporator. In a system in which the compressor is designed to run continuously the valve means I would be without function, but in many modern refrigerators now being built with capillary tube feed devices the compressor is designed to start and to stop or cycle anywhere from 6 to 12 or more times per hour. In such a system the efficiency by incorporating the valve means I would be increased substantially, or in the neighborhood of 15% or more, depending upon the volume within the high side or condenser 9 and conduit 8 and varying in direct proportion therewith.
When the predetermined high temperature of the evaporator 4 has been reached, switch I3 will,
again energize the motor II and start operation of the compressor 1. The first operation is to lower the pressure within the compressor 'I on its inlet side intermediate the outlet thereof and the check valve 32 within inlet 6. This will also lower the pressure within chamber 30 so that the valve member 23 will be moved by the spring 25 to open position. When this said pressure has been r..- duced to or slightly below the pressure within the evaporator 4, the check valve in the inlet 6 Willopen and the system Will act as does a normally operating capillary tube refrigerating system after equilibrium conditions have occurred, and as described hereinbefore.
Operation of the modified valve means I as shown in Fig. 2 is substantially the same as that of the valve means I of Fig. 1, the difference between the two valve means I and I being not in operation but in the details of construction as hereinbefore pointed out.
It may now be seen that by utilizing the herein described invention the efciency of the cycling capillary tube refrigerating systems is increased in a simple, novel and new manner, and one Which is automatic and positive in its operation.
What I claim and desire to secure by Letters Patent of the United States is:
1. In a refrigerating system, evaporating means, means for supplying refrigerant to said means, means for intermittently extracting refrigerant from said evaporating means and discharging the extracted refrigerant into said supplying means, pressure sensitive means interposed between said supplying means and said evaporating means, and means for supplying a pressure to said pressure sensitive means greater than the pressure in said evaporating means upon cessation of said extracting means thereby to cause said sensitive means to stop further flow of refrigerant from said supplying means to said evaporating means.
2. In a refrigerating system, an evaporating means having an inlet and an outlet, a condensingV means having an inlet and an outlet, flow restricting means connecting said condensing means outlet to said evaporating means inlet, means including a check valve connecting said evaporating means outlet to said condensing means inlet, valve means having a pressure operated power element interposed between said now restricting means and said evaporating means inlet and operable upon a predetermined pressure within said element to stop flow of refrigerant to said evaporating means, and pressure conducting means connected to said condensing means and operable to supply a pressure at least as great as said predetermined pressure to said element upon cessation of operation of said condensing means.
3. In a refrigerating system, an evaporator, a compressor for extracting vaporized refrigerant from said evaporator, conduit means connecting said compressor and said evaporator, condensing means for liquefying the vaporized refrigerant discharged from said compressor, capillary tube means for regulating the ow of refrigerant from said condensing means to said evaporator, valve means interposed between said capillary tube means and said evaporator, pressure sensitive means for moving said valve means to closed position, unloader means cooperable with said compressor upon cessation of operation thereof to a1- low the high pressure discharged refrigerant to pass t0 the inlet of said compresson'check valve means interposed between said compressor and s'aid evaporator and operable to prevent backiiow of refrigerantto said evaporator through said conduit means, and conduit means for conveying the high pressure refrigerant passed by said unloader means to said pressure sensitive means so that during periods of cessation of operation of said compressor said first-named valve means acts to stop flow of refrigerant to said evaporator.-
4. In a refrigerating system, an evaporator, a compressor for extracting vaporized refrigerant from said evaporator, conduit means connecting said c'ompressor and said evaporator, condensing means for liquefying the refrigerant discharged from said compressor, capillary tube means for regulating the ow of refrigerant from said condensing means to said evaporator, Valve means interposed between said capillary tube means and said evaporator, spring means urging said valve means toward open position, pressure sensitive means ior moving said valve means to closed position in opposition to said urging means, unloader means cooperabie with said compressor upon cessation of operation thereof 'to allow the high pressure discharged refrigerant to pass to the inlet of said compressor, check valve means interposed between said compressor and said evaporator and operable to prevent back flow of refrigerant tolsaid evaporator through said conduit means, and conduit means for conveying the high pressure refrigerant passed by said unloader Ameans to said pressure sensitive means so that during periods of cessation of operation of said compressor said rst-named valve means acts to stop ow of refrigerant to said evaporator.
FRANKLYN Y. CARTER.