US2351140A - Refrigeration apparatus - Google Patents

Description

June 13, 1944. G. s. MccLOY 2,351,140

REFRIGERATION APPARATUS Filed Nov. 6, 1941 Condeser asl ' vuwlamom GRAHAM S. M? CLoY ATTO EY Patcntcdl June 13, 1944 2,351,140 REFRIGERATION APPARATUS Graham S. McCloy, Springfield, Mass., assigner to Westinghouse Electric a; Manufacturing7 Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 6, will, S No., 4133.984

Claims.

This invention relates to mechanical refrigeration apparatus and more especially to a method and .a device for rapidly defrosting the cooling unit of such apparatus.

@ne object of the invention is to eiect rapid defrosting of the evaporator of a compressorcondenser-evaporator type refrigerating system.

Another object of the invention is to effect defrosting of selected areas of an evaporator.

A further object of the invention is to defrost the shell oi' an evaporator without melting the ice stored in the evaporator.

A still further object of the invention is to provide a multiple valve for reversing the flow of refrigerant in a mechanical refrigerating system.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a schematic drawing of a refrigerating system embodying the defrosting mechanism of this invention the mechanism being shown in the position which produces refrigeration of the evaporator, and

ltig. 2 is similar to Fig. l but with the mechanism shown in the position which produces defrosting 4of the evaporator.

Referring now to the drawings, the reference numeral t0 designates a U-shaped evaporator such as-customarily used in domestic refrigerators. The evaporator includes two refrigerated shelves ll formed by brazing portions of a refrigerant-carrying tube l2 in undulated configuration to the bottom of the shelves II, The tube thereafter communicates with the bottom of the hollow U-shaped evaporator In. Refrigerant is normally supplied to the evaporator Il? through the tube l2, lthe refrigerant passing along along the shelves H. then to the bottom of the hollow U-shaped evaporator I0, and thereupon upwardly through both legs of the U- shaped evaporator to therefrigerant headers I3. The level of the liouid refrigerant is normally located in the headers I3 and the vapors are drawn from the headers I3 through a tube H. through conduits I6 and I1 by a refrigerant compressor I5. 'I'he refrigerant compressor is ldriven by an electric motor and both the compressor and the electric motor are enclosed in a hermetically sealed casing I8.

4The electric motor 20 in the casing I8 i: energized through lines I9 and 2| by means of the connecting lines 22 and 23. The connecting line Cil 2t has a switch it included therein actuated by an expansible bellows 26 which is in communication with a bulb il through a tube 28. The bulb tl contains a volatile liquid which causes the bellows it to expand and close the switch 2t whenever the temperature of the evaporator it rises above a predetermined limit.

The refrigerant vapor withdrawn from the evaporator lll is compressed by the compressor i5 and .passes through tubes 29 and 3l to a condenser 32 wherein the refrigerant vapor is liquiiied, and thereupon passes as a liquid through tubes t3, 3i, 35, 36, and 31 to the aforementioned tube l2. Of these tubes, tube 35 is a flow restrictor such as a capillary tube. The abovedescribed flow of refrigerant is indicated by the arrows of Fig. l.

Fig. 2 shows the flow of refrigerant when the evaporator l@ is being defrosted. During the defrosting, the refrigerant is by-passed around the capillary tube 35 by tubes 38 and 39 so that the evaporator lll is substantially at the same pressure as the condenser 32 and substantially no refrigerant liquid is formed. The ow of refrigerant vapor during the defrosting operation is from the compressor in the casing l 8 through the tube 29, tube M, tube it, and tube i4 to the two refrigerant headers ,i3 from whence it flows downwardly through the two lengths of the U-shaped evaporator itl and upwardly through tube l2, through tube 31, tube 38, tube 39, tube 33, through the condenser 32, through tube 3|, and through tube i1 back to the compressor I5 in the sealed casing i3.

The refrigerant pumped into the evaporator ill during the defrosting cycle is in the form of a vapor at the temperature of the compressor and condenser 32 both of which are at or above room temperatures. 'Ihe relatively warm refrigerant vapor pumped reversely through the evaporator l0 forces the liquid refrigerant therein out through the tube I2 and through tubes 31, 3c, 39, and 33, through the condenser 32, through tubes 3l and ll into the sealed casing I8 where it remains. It will be observed that the shell of the U-shaped evaporator receives the warm refrigerant vapor first of all and will, therefore, be defrosted before the shelves II are defrosted.

The multiple valve mechanism of this invention which effects the reversal of refrigerant ow just described and the mechanism for actuating the compound valve mechanism will now be described. The valve mechanism comprises a hollow cylindrical valve body I2 and a valve stem 43- adapted by guides 44 and 45 for axial movement within and longitudinally of the valve body 42. Two annular, spaced apart, and coaxial recesses -45 and 41 are provided adjacent one end oi' the valve body 42. The annular recess 43 forms two opposite-facing valve seats 43 and 43 and the annular recess 4l forms a similar pair of oppositely-facing valve seats 5| and 52. A valve disc 53 is vsecured to the valve stem 43 to lie in therecess 45 andgeats selectively on the valve seats 43 and 4l depending upon the position of the valve stern 43. A similar valve disc 54 is secured to the valve stem 43 and lies in the annular recess 4l to seat selectively on the valve seat 5| or 52. The respective valve discs 53 and 54 are spaced to seat simultaneously on the valve seats 49 and 52 and likewise simultaneously on the valve seats 43 and 5I.

A further valve seat 55 is formed in the cylindrical body 42 adjacent the other end thereof, and a valve disc 59 is secured to the valve stem 43 to engage the seat l5 simultaneously with the engagement of seats 43 and 52 by the valve discs 53 and 54, respectively. A disc 51 is secured to the valve stem 43 between thevalve discs 54 and 56. A cylindrical flexible bellows 58 is secured at one of its edges to the disc v57 and the other of its edges is secured to an angular shoulder 59 formed in the interior of the cylindrical valve body 42. The valve seats 49, 52, and 55 and the flexible bellows 58 are of substantially the same diameter. The bellows 53 forms a seal between the valve stem 43 and the valve body 42.

It will be apparent from an inspection of Fig. 1 that when the valve member 43 is in the lower position, the refrigerant flowing from tube 29 is transferred to tube 3|, that the by-pass, comprising tubes 38 and 39, around the capillary tube 35 is closed, and that the refrigerant issuing from tube I5 is transferred 'to tube i1. In like manner an inspection of Fig. 2 will disclose that when the valve stem 43 is in the upper position, the refrigerant issuing from the tube 29 is directed to flow through tube 4I and thence through tube I6, the refrigerant flowing from tube 31 is permitted to flow through the by- pass comprising tubes 33 and 39, and the refrigerant flowing from tube 3| is directed to flow through tube I1.

The movement of the valve stem 43 is effected by an electro-magnet 35 which actuates an armature 66 aillxed to one end 51 of the valve stem 43 which end 81 projects through an Aopening which also constitutes the guide 45. A sealing cup 68 is interposed between the electro-magnet 65 and the armature 55 to effect a seal for the opening in the valve body 42 comprising the guide 45. The sealing cup 68 is brazed at its edges to the valve body 42 and preferably constitutes nonmagnetic metal such as brass. When the electro-magnet 55 is energized. the armature 66 and the valve stem 43 is pulled to its upper position and when the electro-magnet 65 is deenergized a spring 59 moves the valve stem 43 and the armature 65 to its lower position.

The power required to actuate the valve stem 43 is not very great because the valve stem 43 and the valve discs 53, 54, 56, and the disc 51 and bellows 58 comprise a balanced valve system when the valve stem 43 and the structures connected thereto are at the lower position as shown in Fig. 1. Assuming that the compressor of the refrigerating system is in operation, the high pressure above the valve disc 53 is balanced by the high pressure belowthe valve disc 54 and likewise the high pressure above the disc 5l is 4balanced by the high pressure below the valve disc 53. To insure such balanced action it is necessary that the sum of the effective areas of the valve discs 54 and 53 when seated on the valve seats v52 and l5, respectively, is equal to the sum of the eective area of the valve dsc 53 vwhen seated on the valve seat 49 and the ei'- fective cross-sectional area ot the bellows 58. When the compressor oi' the refrigeratlng system is not in operation and also when the valve stem 43 is in the upper position as shown in Fig. 2, the pressures in all of the portions'of the valve body 42 are substantially equal so that the valve system is also balanced during these conditions.

The electro-magnet 85 is energized periodically for a short period, preferably each night, by an electric clock mechanism 1|, which clock mechanism H receives its energy from lines I 9 and 2l through leads 12 and 13. The electric clock mechanism 'il is arranged to close a switch 'i4 located in a lead 15 which supplies the electro-magnet 35 with power from the line 2i. Another lead 19 supplies the electro-magnet 55 with power from line I9. The electric clock 1| also closes a switch I1 lying in the lead 18 which shunts the switch 24 to insure operation of the refrigerating mechanism regardless of the position of switch 24 so that whenever the clock mechanism 1l raises the valve stem 43, the compressor pumps warm refrigerant vapor through the evaporator l 0 to defrost the same. l

It will be apparent from the above that this invention provides a method and means for rapidly defrosting an evaporator of a refrigerating system, that the shell portion of the evaporator is defrosted before the shelves o1' the evaporator are defrosted so that ice stored on the shelves will not melt if the defrosting period is not of too long a duration. It will also be apparent that this invention provides a novel valve structure by means of which this result can be accomplished.

While I have shown my invention in but one form, it will vbe obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications Without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I- claim is:

1. In a defrosting valve for a compressorcondenser-evaporator type refrigerating system in which a fixed orifice controls the flow of refrigerant to the evaporator, the combination of a hollow valve body having two annular, coaxial, and spaced-apart recesses in the interior thereof. each of said annular recesses providing two oppositely-facing valve seats, an annular shoulder in said valve body coaxial with said annular recesses, said annular shoulder being spaced from said two spaced-apart recesses and providing an additional valve seat, a valve stem in said body adapted for longitudinal movement, three valve discs on said valve stem adapted to simultaneously seat respectively on said additional valve seat and on said valve seats facing in the same direction as said additional valve seat when the'valve stem is in one position and two oi.' said valve discs being adapted to simultaneously seat respectively on the remaining two of said valve seats when the valve stem is in another position, sealing means between the valve stem and the valve body located between the said annular shoulder, said valve body having a' plurality -of ducts communicating with the exterior thereof, one of said ductscommunicating l with the space between' the annular shoulder" andA the end of said body beyond said shoulder, another communicating with the 'space between ksaid shoulder and said seal, another communicating with the space between said sal and the' annular recesses nearest to said seal and with the space beyond the annular recess farthest from said seal and the end of said-body adjacent said last-mentioned recess, another duct communicating with o'ne of said annular recesses at a point between the valve seats thereof,'another duct communicating with the other of said annular recesses at a point between the valve seats thereof, and another of said ducts communicatingwith the space between said recesses.

2. The method of defrosting the evaporator of a compressor-condenser-evaporator refrigerating system having a restrictor for controlling the ilow of refrigerant to said evaporator, said evaporator having portions primarily for the storage of frozen material and other portions primarily for maintaining an insulated space at low but above freezing temperatures, the flow of refrigerant during normal operation of said refrigerating system being from said firstnamed portions to said second-named portions. said method comprising rendering said restrictor ineffective and reversing the ow of refrigerant through said evaporator for a period of time sufficient to substantially defrost said evaporator but insuiiicient to melt substantial portions of the frozen material which may be stored in the portion of the evaporator provided for the same and thereafter again rendering said restrictor effective and resuming the normal flow of the refrigerant through the evaporator.

3. In refrigerating apparatus, the combination of a compressor, a condenser, a flow-restricting passage. and an evaporator defining an elongated conduit, tubing connecting said compressor, condenser, flow-restricting passage, and

evaporator in normal operating relationship, wherein the refrigerant passes through the elongated conduit of the evaporator in one direc-1 tion, a reversing valve and tubing connected to said apparatus, said reversing valve being movable selectively to two positions one of which produces flow of said refrigerant in said one direction through the elongated conduit of the evaporator and the other of which positions Vproduces flow of said refrigerant through said elongated conduit in a. direction reversely to said one direction, a second valve, tubing connecting said second valve in parallel with said now-restricting passage, and means interconnecting said second valve with said reversing valve to close said second valve when the reversing valve is positioned to direct the flow of said refrigerant through the elongated conduit of the evaporator in said one direction and to open said second valve when said reversing valve is positioned to direct the flow of refrigerant through the elongated conduit of the evaporator in a. direction reversely to said one direction of i the refrigerant therethrough.

4. In refrigerating apparatus. the combination of a compressor, a condenser, an evaporator, a ow-restricting passage, a flow-reversing valve, tubing connecting said condenser, owrestricting passage, an evaporator in series, additional'tubing connecting said flow-reversing valve with said compressor, condenser, and evaporator, in operating relationship whereby said reversing valve functions to direct the flow of refrigerant from the compressor selectively either through the condenser and thereafter through the evaporator in one direction or through the evaporator in the opposite'direction and thereafter through the condenser, a second valve, tubing connecting saidsecond valve in parallel with said now-restricting passage, said second valve being interconnected with said reversing valve to operate simultaneously therewith.

5. In refrigerating apparatus, the combination of a compressor, a condenser, an evaporator, a flow-restricting passage, a now-reversing valve, tubing connecting said condenser, nowrestricting passage, and evaporator in series, additional tubing connecting said flow-reversing valve with said compressor, condenser, and evaporator, whereby said reversing valve functions to direct the flow of refrigerant from the compressor selectively either through the condenser and thereafter through the evaporator or through the evaporator and thereafter through the condenser, a second valve, tubing connecting said second valve in parallel with said flowrestricting passage, said second Valve being interconnected with said reversing valve to close when the reversing valve directs the ow of the refrigerant through the condenser and thereafter through the evaporator and to open when the reversing valve directs the iiow of a refrigerant through the evaporator and thereafter through the condenser.

- GRAHAM S. McCLOY.

A CERTIFICATE OF CORRECTION. Patent No. 2,551,1ho. Y June 15. 19141;.

GRAHAM S. HCCLOY.

It 1s hereby certified ta't error appears in the Vpinted specification 'of the above numbered. patent requiring correction asfollows: 'Page 1,*f`1z-st column; line 14.1, vbefore thewords "the shelves'I strike out "along"4 second occurrence; page 5, eeeondcolwn'n, line 19, claim 14:, for "an" read' --and--g and that the said Letters Patent should be readvth this correctiori there 1n that the same may conform to the record -of the case in the Patent Office.

sign-a and sealed this 15th day of August, A. D. 191m.

Leslie Frazer (Seal) Y Acting Commissioner of Patents.

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