US2095010A - Refrigerating apparatus - Google Patents

Description

Oct. 5, 1937. 1.. A. PHILIPP REFRIGERATING APPARATUS I Filed March 16, 1933 3 Sheets-Sheet 1 INVENTOR. Law/game I]. PHIL/PP BY g ATTORNEY.

Oct. 5, 1937. A." PHILIPP REFRIGERATING APPARATUS Filed March l6, 1933 3 Sheets-Sheet 3 INVENTOR. fiwzwl: 4. P/lIL/PP ATTORNEY.

Patented Oct. '5, 1937 UNITED STATES 2,095,010 REFRIGERATING APPARATUS Lawrence A. Philipp, Detroit, Mich, assignor, by

mesne assignments, to Nash-Kelvinator Corporation, Detroit, Mich., a corporation of -Maryland Application March 16, 1933, Serial No. 661,033

25 Claims.

This invention relates to refrigerating apparatus, and more particularly to refrigerating apparatus of the multiple temperature type.

. One of the objects of my invention is to provide a new and improved arrangement for freezing substances and for cooling circulating air in a refrigerator cabinet.

Another object of my invention is to provide an improved and simplified arrangement for obtaining a temperature differential between a number of different refrigerant evaporators.

Another object of my invention is to provide for maintaining a substantially constant temperature differential between a number of different refrigerant evaporators without the necessity of making adjustments although various average mean temperatures are sought to be attained in the different evaporators.

Another object of my invention is to provide an improved unitary refrigerating system in a refrigerator cabinet, which system includes a refrigerant condensing element, a low temperature refrigerant evaporator for freezing large quantities of ice cubes and the like, and a relatively high temperature refrigerant evaporator for cooling circulating air in the food compartment of the cabinet, and to provide for controlling the operation of the condensing element in response to changes in temperatures in the relatively high temperature evaporator, and also to provide an improved arrangement for maintaining a substantially constant temperature differential between said evaporators which permits a large quantity of substances to-be frozen to be applied to the low temperature evaporator without effecting the average temperatures maintained in the air cooling evaporator, while at the same time the operation of the condensing element continues until the heat of the substances to be frozen is substantially or entirely absorbed by the low temperature evaporator.

Another object of my invention is to provide within a refrigerator cabinet an improved arrangement of and control for refrigerant evapcrating means which is arranged and operated without the collection of frost thereon or a slight film of frost is allowed to collect thereon during the on-phase of the refrigerating cycle and is melted off during the off-phase of the refrigerating cycle, while at the same time provisions are made for freezing substances, such as ice cubes and the like, and for cooling circulating air in the food storage compartment whereby continuous refrigeration at substantially constant, predetermined temperatures is assured and the necessity of periodic inoperative conditions of the system for defrosting is avoided.

-Another object of my invention is to provide an improved arrangement for the ready removability of the aforesaid refrigerant evaporators 5 and the condensing elementas a unitary structure without uncoupling the devices from one another. 0

Other objects and advantages will be apparent from the following description, reference being 10 had to the accompanying drawings.

In the drawings:

Fig. 1 is a side vertical view in cross section of a refrigerating apparatus embodying features of my inventon; 15

Fig. 2 is a view taken along the line 2- -2 of Fig. 1;

Fig. 3 is a horizontal view in cross section of the apparatus embodying features of my invention; I 20 Figs. 4 to 6 are graphs indicating the cyclic operations of the system under various conditions;

Fig. '7 is a vertical view in cross section .of a control valve embodying features of my inven- 25 tion;

Fig. 8 is a diagrammatic representation of the switch mechanism used for controlling the operation of the system;

Fis. 9 is a side vertical view in cross section 30 of a modified form of refrigerating apparatus embodying features of my invention;

Fig. 10 is a front view partly in elevation and partly in cross section of the apparatus shown in Fig. 9; and 35 Fig. 11 is a view taken along the line H--ll of Fig. 7.

' lated wall 32. The wall 32 extends across the width of the cabinet and from the rear wall to a point adjacent the front wall, separating the food compartment from the freezing compart- 50 ment and machine compartment. An inner metallic lining member 35 forms 'the inner walls of the food compartment and is, preferably, provided with a coating of vitreous enamel, such as porcelain, to provide a neat appearing compart-, 55

ment and one which may be easily cleaned. The front wall 28 is provided with an opening 31 through which access may be had to the food compartment and freezing compartment. The opening 81 is closed by door 38.

A unitary structure is arranged to be inserted in and removable from the cabinet through the door opening 81. This structure comprises, in general, a refrigerant evaporating element 40, a refrigerant condensing element 42, an upright partition or closure member 44 between said ele ments, and a refrigerant evaporating element 46. When the removable structure is in operative position in the cabinet the upright partition 44 separates the machine compartment 24 from the freezing compartment 28. Thus, the condensing element is located in the rear of the cabinet and the cooling element 48 is in substantially horizontal alignment therewith at the front of the cabinet.

As shown in the drawings, the refrigerant evaporating element 48 is of the flat plate type and is horizontally disposed substantially midway between the top wall 88 and the wall 32 in the compartment 28. The evaporator 48 may be secured to the upright partition 44 by any suitable means. Preferably, the element 40 is constructed of sheet metal plates which are secured together about the peripheries thereof by seam welding and welded at various points intermediate their edges, but spaced apart between the welded points to provide a space for refrigerant. By locating the evaporating element 40 substantially midway between the walls and 32, and by operating said element at temperatures sufficiently low enough to freeze substances, said substances may be frozen rapidly by placing same on the upper part of the evaporating element and if desired, when frozen, may be removed to be stored and retained in a frozen condition by placing same on the upper part of the wall 32 in compartment 22 immediately below the evaporating element 48. In the drawings I have shown conventional ice trays 48 mounted on top of the element 48 to freeze substances therein. When the substances are frozen, the trays may be transferred to the space immediately below the evaporating element and additional trays may be mounted on the plate evaporating element to freeze additional substances therein. Thus, it will be noted that I have provided for rapidly freezing large quantities of ice cubes or other substances,- and in addition I have provided a large space for storing said substances in a frozen condition.

In order to prevent the circulating air in the food storage compartment 22 from entering the freezing compartment 23, I have provided a closure plate 88 for the front of compartment 28. Plate 68 is provided with openings 62 closed by doors 88. Doors 88 and openings 52 provide ready access to the interior of compartment 23.

Evaporating element 46 may be of similar construction as evaporating element 40 and is vertically disposed in the food storage compartment adjacent the rear wall 21 but slightly spaced therefrom to permit circulating air in the compartment 22 to pass on all sides of the element 46. A plurality of U-shaped heat absorbing fins 55 are secured to the one side of evaporating element 46 to increase the heat transfer characteristics thereof.

The refrigerant condensing element 42 comprises, in general, a motor compressor unit 88,

eous refrigerant and delvers' it to the condenser 62 wherein it is liquefied d from which it is delivered to the high side float mechanism 65. Liquid refrigerant is delivered to the evaporating elements through conduit 68 under the control of the high side float mechanism 65. The electrically operated fan 63 is employed for circulating a blast of air over the condenser 62 to aid in condensing the refrigerant and for circulating air about the compartment 24.

Liquid refrigerant is first delivered to the evaporating element 46 through the conduit 68, and from the evaporating element 46 liquid and gaseous refrigerant is delivered to the evaporating element 46 through a conduit 18. Evaporated refrigerant is withdrawn from the evaporating element 40' through the vapor conduit 61.

As will be noted in Fig. 2 of the drawings, the wall 32 is provided with notches 12 for receiving conduits 10 and. 68. The notches 12 extend from a. point in the wall 32 adjacent the partition 44 to the front of wall 32 to permit the ready, removal of the evaporating elements 40 and 46 and condensing element 42 without uncoupling said devices from one another, as is hereinafter more fully described. The notches 12 are normally closed by slabs of insulating material 15.

Preferably, the condensing element is intermittently operated. In order to control the oper-- ation of the condensing element, I have provided a thermostatically controlled switch 88 to which is connected a thermostat fluid containing bulb 82 which is disposed in thermal contact with the evaporating element 46 so that the switch operates in response to changes in temperature within the evaporating element 46. The switch '88 is adapted to open and close the circuit to the motor of unit 60 in response to predetermined'changes in temperature within the evaporating element 46. In view ,of the fact that the evaporating ele ments 48 and 46 are of the so-called flooded type, the temperature therein will bear a direct relation to the pressures existing therein.

Referring in detail to Fig. 8, the thermostatic switch 88 comprises, in general, a casing 85 which houses the operating parts of the switch. The switch mechanism includes an expansible bellows 81, which is connected to the thermostatic bulb 82 by means of a conduit 88. The bellows 88 is disposed in engagement with a pivotally mounted lever 80 which moves upwardly and downwardly, depending upon the movement of the bellows 81.

The lever 98 is adapted to actuate suitable leverage mechanism 82 for controlling the opening and closing of contacts 84. .Contacts 84 control an electric circuit 96 which leads to the motor to thereby control the flow of current from power mains 98 to the motor. A spring I88 is provided for controlling the movement of bellows 81 to thereby control the operation of switch 88 so that the motor may be cut in or cut out of circuit between predetermined operating limits. A screw l8| is provided for varying the efiectiveness of spring I08 to thereby vary the cut in and cut out periods of the motor of unit 68. Thus, the thermostatic switch 88 controls the operating periods i of the condensing element 9 thereby control the temperatures within the evaporaflng elements 46 and 46. It will also be noted that the switch is controlled in response to changes intemperatures within the evaporating element 46.

In order to maintain a predetermined temperature differential between the evaporating element 46 and the evaporating element 46, I have provided a pressure responsive valve I66 which is interposed in the conduit 16 for controlling the flow of liquid and gaseous refrigerant fromthe evaporating element 46 to the evaporating element 46. The pressure responsivevalve I65 is adapted to maintain a predetermined pressure differential between the evaporating. element 46 and the evaporating element 46 to thus maintain a temperature differential between said evaporating elements. As shown in Fig. 7, the pressure responsive valve includes a valve proper I61 and a valve seat I66 located within a casing I69. The casing I66 is provided with an inlet II6 to which the outlet end of conduit I6 is connected, and an outlet III. The evaporating element 46 is connected to outlet III. The valve proper IN is secured to a weight H6 which is adapted to move upwardly and downwardly within a chamber I I6, depending upon the pressure of the refrigerant exerted on the valve proper I61. Preferably, the chamber H6 is cylindrical in shape and also, preferably, the weight I I6 is provided with a plurality of arcuate portions II6 which conform to the contour of the walls of the chamber. The weight is also provided with cutaway fiat portions II6 between the arcuate portions II8 to provide spaces between the walls of the chamber ment 46. When the pressure recedes to a preing elements 46 and 46.

determined point (for example, to a point less than that required to open valve I61) the weight and valve proper move downwardly to cause the valve I61 to engage itself with seat I66 to prevent further passage of refrigerant into the evaporating element 46. The weighted valve is arranged to be intermittently operated so as to maintain a predetermined pressure differential between the evaporating elements 46 and 46. As previously stated herein, the pressure differential is controlled by the weight of the weighted valve proper I61. In other words, before refrigerant may pass from the evaporator 46 to the evaporating element 46, the pressure within the evaporating element 46 must be equal to the pressure in the evaporating element 46, plus an amount equal to move the weight II5 upwardly to remove the valve I61 from its seat I68. This predetermined pressure differential is maintained irrespective of the temperatures maintained in the evaporat- Preferably, the thermostat is set so that the evaporating element 46 will be operated at temperatures which causes rapid freezing, and the evaporating element 46 at temperatures which are slightly above that which would be likely to cause the collection of frost or ice thereon due to the deposit of moisture from the circulating air in the food compartment. If desired, the thermostat may be set to operate evaporating element 46 at a temperature which would allow a slight film of ice to collect thereon during the on-phase of the refrigerating cycle and melted off during the off-phase of the refrigerating cycle. In view of the fact that the refrigerant-condensing element 42 is operated in response to changes intemperature within the evaporating element 46, the adjustable spring I66 of thermostat 66 may be set so as to providefor operating the evaporating element 46 at either of the desired temperatures. In the refrigerating system herein described, I prefer to use sulphur dioxide asthe refrigerant. When sulphur dioxide is used as the refrigerant and when a predetermined setting of switch 66 is made, I have found that the cyclic operation of the system is as indicated by the graphs shown in Figs 4 and 5.' In Fig. 5, as illustrated, the normal cycling is between an upper pressure range limit E, and a lower pressure range limit F. E represents the pressure existing in evaporating element 46 when the motor of unit 66 is cut in to operate the compressor of said unit, and F represents the pressure in said element when the motor is cut out of circuit to render the compressor inoperative toperform its compressing function. When sulphur dioxide is used as the refrigerant, the upper pressure range limit E may be fourteen pounds pressure and the lower pressure range limit may be four pounds pressure of the refrigerant in element 46. In Fig. 4, it will be noted that the normal cycling takes place between an upper limit A and a lower limit-.13 in element 46. The upper limit A and the lower limit B may be four pounds pressure and six inches of vacuum, respectively. Thus, it will be noted that a predetermined pressure differential at seven pounds is maintained between elements 46 and 46 while the unit is operating during normal cycling operation and this is accomplished by the weighted valve I65, and the operation of the unit 66 is controlled by thermostatic switch 86 in response to changes in temperature in evaporating element 46.

Assuming now a large quantity of substances to be frozen is applied to the ice freezing plate or evaporating element 46, the pressure of the refrigerant in element 46 is increased by the heat of the substances and the element 46 operates on a curve different from the normal cycling curve between the A and B limits. As shown in Fig. 4, the upper limit is at C, which is, for excreased until the desired pressure differential is.

atta ned by the valve I65. As will be noted, the pressure differential maintained by the valve I65 during operation of the condensing element is seven pounds since the lower pressure limit B of element 46 is 6 inches of vacuum, and the lower;

pressure limit E of element 46 is four pounds pressure of the refrigerant when the unit 66 ceases operation. As indicated, the pressure range in element 46 is varied with the upper limit being at G, which is, for example, sixteen pounds. pressure, and the lower limit H, which is four pounds pressure of the refrigerant. Thus, it will be noted, that as the temperature in element 46 rises to a temperature corresponding to fourteen pounds pressure, the thermostatic switch 85 cuts in the motor-compressor unit 60 to reduce the pressures in the elements and 46, which gradually takes place as the heat of the sustances to be frozen is gradually dissipated by being absorbed in the refrigerant and withdrawn from elements 40 and 46 by the motor-compressor unit. As will be noted in Figs. 4 and 5, the placing of a large quantity of substances to be frozen in the element 40 causes the elements 40 and 46 to operate on curves 0-D and GH, respectively, which are at pressure range limits different from normal cycling, and'it is also to be noted that the average mean temperatures existing in the evaporating elements are substantially the same as the temperatures existing therein during normal cycling. Thus, it will be noted that the placing of a large quantity of substances to be frozen on element 40 will, after operation of the motor-compressor unit has started, cause it to continue to operate until the substances are either entirely or substantially frozen even though the operation of the motor-compressor unit is controlled in response to changes in temperatures in the evaporating element 46. This is due to the pressure diflerential maintained by valve I05 which prevents the pressure in element 46 to be lowered to four pounds until the pressure in element 40, is lowered to six inches of vacuum, at which time the substances are frozen. In the event an abnormal large quantity of warm foods should be placed in the food compartment, the pressures in each evaporating element is similarly increased until lowered by the action of the condensing element 42.

.Although I have disclosed my pressure differential valve I05 in connection with an intermittently operated refrigerating system, it will be readily apparent from the foregoing that in a continuously operated system the valve I05 would maintain a predetermined pressure differential between the elements 40 and 46 at all times.

v In Fig. 6 there is shown a graph indicating normal cycling operation between predetermined upper and lower pressure range limits in which I is the upper limit and J the lower limit. The pressure limits I and J may correspond to upper and lower limits E-F with respect to evaporating element 46 during normal cycling at a predetermined setting of switch 05. However, when it is desired to operate the system at a higher pressure range, the upper and lower pressure limits may be varied by adjustment of screw IM to vary the effectiveness of spring I00. 'As shown, the upper and lower limits have been increased with the upper limit being at K and the lower limit at L. By varying the upper and lower pressure range limits in the evaporating element 46, the upper and lower pressure range limits are correspondingly varied in the evaporating element 40 owing to the pressure responsive valve I05, which maintains a'predetermined pressure differential between the two evaporating elements 40 and 46 From the foregoing, it will be noted that I have provided an improved and simple arrangement for maintaining a pressure differential between a number of different evaporating elements for maintaining a temperature differential there;- between. It will also be noted that the pressure differential is obtained automatically throughout variations in pressure range limits existing in the different evaporating elements. In addition, it is to benoted that the pressure range limits may be set at any desired operating limits by simply adjusting a single manually operable screw without inany way effecting the temperature differential maintained between the different evaporating elements by the provision of the pressure responsive valve I05. Furthermore, it will be noted that in maintaining a predetermined pressure differential rapid ice freezing is promoted, since the condensing element when once started continues to operate until the ice is frozen. I

As previously stated herein, the entire refrigerating system may be removed from the cabinet as a unitary structure. The structure includes the condensing element 42, upright separating wall 44, metallic member I22, which includes an upright portion which is secured to wall 44 and a horizontal portion which rests on wall 32, evaporating element 46, evaporating element 40, a sheet metal member I24, which includes an upright portion which is secured to the wall 44 and a horizontal portion which rests on wall 32, front closure plate 50 and doors 53. Preferably, the evaporating element is secured to rear wall 21 by screws (not shown) so that it may be readily removed from the wall 21. The entire structure as a unit may be moved forward with portions above wall 32 sliding thereon and the conduits 60 and 10 moving in slots or notches 12. The entire structure, after clearing wall 32, may be removed from the cabinet through opening 31.

Referring now to Figs. 9 and 10, there is shown a cabinet I30, which is similar to cabinet 20, and includes a food storage compartment I32, machine compartment I34 and a freezing compartment I35. The cabinet is formed of insulated walls, including top wall I31, bottom wall I38, rear wall I33, front wall I40, a substantially horizontal, fixedwall I43 located between the top wall I31 and bottomwall I38 to separate the food compartment I32 from compartments I34 and I35, and upright wall I45 between compartments I34 and I35. The front wall I .40 is provided with an opening I through which access may be had to compartments I32 and I35. The opening I50 is closed by door I5I. The upright wall I45 is provided with an opening I52 which is closed by a movable closure wall I54. The closure wall is adapted to support a primary refrigerant evaporator I56 within compartment I35 and an intermittently operated refrigerant condensing element I50, which may be similar to element 42, within compartment I34. The condensing element is operatively connected to the evaporating element I by conduits I and I6I. of compartment I35 is arranged to be closed by a closure plate I 65, which is provided with an opening I66 through which access to the interior of compartment I35 may be had. If desired, the opening I66 may be closed by doors (not shown) similar to doors 53 shown in Figs. 1 and 2. Preferably, the apparatus including condensing element I50, evaporating element I56, wall I54 and front closure plate I are removed from the cabinet as a unitary structure by simply moving same forward through opening I50. The operation of element I56 may be controlled by any suitable control means (not shown).

In order to cool the food compartment I32, I have provided a secondary refrigerant evaporating element I10. The element may be similar to The front element 45 and is located in the cabinet in a like 1 2,095,010 the element I I through a single conduit I12.

The conduit I12 is connected to a condenser I'Il disposed immediately below the evaporating element I56 and in thermal contact therewith to effect condensation in the condenser I'Il. Evaporated refrigerant passes from evaporating element I10 through conduit 2 to condenser I14 wherein it is condensed by the refrigerating action of element I56, and the liquefied refrigerant is returned to the evaporating element I10 through conduit I12. If desired, a baflle H5 is placed in front of the element I'III- to direct the air flow about the element I'Ill.

In the apparatus shown in Figs. 9 and 10, the primary system, including the condensing element and evaporating element I56, may be removed for repairs and the like while the secondary system is, preferably, permanently installed in the cabinet, for the reason that the secondary system has no operating mechanism to necessitate repairs.

Preferably, the contact between the condenser I" and the evaporating element I56 is such that during periods when the condensing element I58 is inoperative or, in other words, during the off-phase of the refrigerating cycle, the condensing surface is inadequate to condense all of the evaporated refrigerant in the secondary system which permits the element H0 to warm up to thereby melt the frost formed on its exterior surface. Thus, the evaporating element I56 may be operated at temperatures sufficiently low enough for freezing purposes and the evaporating element I10 is arranged to automatically defrost itself between off and on-phases of the refrigerating cycle. Inasmuch as the evaporating element is closed to the circulating air in the compartment I32, it will be unnecessary to frequently, if at all, defrost this element.

Although only a preferred form of the invention has been illustrated, and that form described in detail, it will be apparent to those skilled in the art that various modifications may be made therein Without departing from the spirit of the invention or from the scope of the appended claims.

What I claim as my invention is:

1. A refrigerating system including heat absorbing means arranged to be operated at variable pressure range limits, and means connected in said system for maintaining during the entire operation of said system a substantially constant pressure differential between different portions of the heat absorbing means to maintain different temperatures in the different portions 7 thereof.

system including a refrigerant evaporating ele- A ment, a second refrigerant evaporating element, means connected in said system for operating said evaporating elements at a substantially constant pressure differential, and control means for the system, said control means being adjustable to vary the operating pressure range limits without effecting the pressure diflerential maintained in said elements. Y

4. A refrigerating system comprising a refrigerant evaporating element, a second refrigerant evaporatingelement, means associated with said elements for reducing the pressures of the refrigerant in said elements, and means for maintaining a substantially constant pressure differential between said elements during the entire time that the pressures are being reduced therein.

5. A refrigerating system comprising a refrigerant evaporating element, a second refrigerant evaporating element connected in series with the first element, means associated, with said elements for reducing the pressures of the refrigerant in said elements, and means for obtaining a predetermined pressure differential bebeing arranged to maintain said predetermined pressure differential until the compressing means ceases operation, and means for controlling the operation of said compressing means.

'7. A refrigerating system comprising, a number of different refrigerant evaporators, an intermittently operating refrigerant condensing element connected to the said evaporators for withdrawing gaseous refrigerant from said evaporators, condensing the gaseous refrigerant and for delivering refrigerant to said evaporators, means for controlling the operation of said condensing element, said means being adjustable to modify the operating periods of said condensing element, and means for automatically maintaining a predetermined pressure differential between the different evaporators throughout variations in operating periods of said condensing element.

8. Refrigerating apparatus comprising, in combination, a refrigerant evaporator, a second refrigerant evaporator associated with the first named evaporator, and a pressure responsive valve for controllingthe flow of liquid and gaseous refrigerant from the first to the second refrigerant evaporator said valve being operable at a predetermined pressure differential between said evaporators to maintain said differential substantially constant.

9. Refrigerating apparatus comprising, in combination, a refrigerant evaporator, a second refrigerant evaporator, and an intermittently operated weight valve operable to allow the flow of liquid refrigerant from the first named evaporator to the second evaporator when the pressure in the first evaporator is equal to the pressure in the second evaporator plus an amount sumcient to move said weight valve.

10. Refrigerating apparatus comprising, in combination, a refrigerant evaporator, a second refrigerant evaporator connected in series with the first evaporator, a condensing element connected to said evaporators, means associated with the first named evaporator for controlling the operation of said condensing element, and means 11. A refrigerating system comprising an air cooling evaporator, an ice freezing evaporator, a

refrigerant condensing element associated with said evaporators, a device responsive to changes in temperatures in said air cooling evaporator for controlling the operation of said condensing element, and means for maintaining a predetermined pressure diii'erenthl between said evaporators whereby a demand for refrigeration by the ice making evaporator will modify the fiow of refrigerant from the air cooling evaporator to cause operation of the condensing element continuously until the ice is in a frozen condition.

12. Refrigerating apparatus comprising, in combination, heat absorbing means including a portion adapted tobe positioned in a compartment for cooling circulating air therein and having a large area exposed to said circulating air, and said heat absorbing means including a second portion shielded from said circulating air not deposited on said second portion and the heat of the circulating air does not warm up said second portion as rapidly as the first portion, means for delivering liquid refrigerant first to said first portion and then to said second portion, means for controlling the operation of said apparatus in such a manner thatfrost does not accumulate on said first portion at least part of the time, and valve means for controlling the flow of liquid and gaseous refrigerant from the first portion to said second portion for causing operation of said second portion at a low temperature.

13. Refrigerating apparatus comprising, in combination, heat absorbing means including a refrigerant evaporating element adapted to be positioned in a compartment for cooling circulating air therein and having a large area exposed to said circulating air, and said heat absorbingmeans including a second refrigerant evaporating element shielded from said circulating air whereby the moisture in said circulatingair is not deposited on said second element and the heat of the circulating air does not warm up said second element as rapidly as the first named element, means for delivering liquid refrigerant first to said first named element and then to said second element, thermostatic means associated with said first element for controlling the operation of said apparatus in such a manner that frost does not accumulate on said first element at least part of the time, and valve means to control the flow of liquid and gaseous refrigerant from the first evaporating element to the second evaporating element for causing operation of said second portion at a low temperature.

14. A refrigerating system of the flooded type comprising a refrigerant evaporating element adapted to be positioned in a compartment for cooling circulating air, a second refrigerant evaporating element for freezing substances, a refrigerant condensing unit associated with said elements, a high side float mechanism for controlling the fiow of refrigerant to said first element, conduit means for conducting the flow of refrigerant to the second element after the refrigerant has passed through said first element, means directly responsive to the condition of said first element for controlling the operation of said condensing unit, and a pressure responsive valve interposed between said, evaporating elements to control the fiow of liquid and gaseous refrigerant from the first refrigerant evaporating element to the second evaporating element for obtaining a temperature differential therebetween.

15. Refrigerating apparatus comprising a refrigerant evaporator adapted to be positioned in a cabinet for cooling circulating air therein and having a relatively large area exposed to the circulating air in the cabinet, a refrigerant evaporator shielded from said circulating air and having provisions for supporting an ice making receptacle in intimate thermal contact with the refrigerant therein, liquid refrigerant conduit means associated with said evaporators, means for maintaining said evaporators substantially flooded with liquid refrigerant, and valve means to control the flow of liquid and gaseous refrigerant from the first named evaporating element to the second named evaporating element for obtaining a pressure difierential between said evaporators. I

16. Refrigerating apparatus comprising a refrigerant evaporator adapted to be positioned in a cabinet for cooling circulating air therein and having a relatively large area exposed to the circulating air in the cabinet, a refrigerant evaporator shielded from said circulating air, a liquid refrigerant conduit interconnecting said evaporators for conducting liquid and gaseous refrigerant from one evaporator to another, a pressure responsive valve in said conduit to control the flow of said liquid and gaseous refrigerant to obtain a pressure differential between said evaporators, means for maintaining a substantially constant quantity of liquid refrigerant in said evaporators, and a thermostat responsive to changes in temperatures in said first named evaporator for controlling said latter means.

17. A refrigerating system comprising a number of difierent refrigerant evaporating elements connected in series, a refrigerant condensing element, and means for maintaining a predetermined pressure difierential between said evaporaating elements and to permit the flow of liquid and gaseous refrigerant from one evaporating element to another and the simultaneous reduction in pressures in said evaporating elements during the entire operation of said condensing elements, comprising a valve-connected between said evaporating elements and operable to open and close by the difference in pressures in said evaporating elements.

18. A refrigerating system comprising a number of dififerent refrigerant evaporating elements, a refrigerant condensing element, and valve means operable to maintain a predetermined pressure differential between said evaporating elements and to permit the simultaneous reduction in pres sures in said evaporating elements during the entire operation of said condensingelement.

19. A refrigerating system comprising a plurality of refrigerant evaporating elements connected in series, a refrigerant condensing element, and means for maintaining a predetermined pressure differential between said evaporating elements and to permit the flow of liquid and gaseous refrigerant from one evaporating element to another and the simultaneous reduction in pressures in said evaporating elements during the entire operation of said condensing element, comprising pressure diiferential means connected between said evaporating elements and arranged to control the flow of liquid and gaseous refrigerant by the difference in pressures in said evaporating elements.

20. A refrigerating system comprising a refrigerant evaporating element having an inlet and a single outlet, av second refrigerant evaporating element having a single inlet and an outlet, pressure differential means associated with the single outlet of the first named evaporating element and the single inlet of the second named evaporating element for controlling the fiow of liquid and gaseous refrigerant from the first to the second named evaporating element, and a refrigerant condensing element associated with said evaporating elements.

21. Refrigerating apparatus comprising, in combination, heat absorbing means including a portion adapted to be positioned in a compartment for cooling circulating air therein and having a large area exposed to said circulating air, means providing an insulated compartment, and said heat absorbing means including a second portion disposed in said insulated compartment so as to be shielded from said circulating air whereby the moisture in said circulating air is not deposited on said second portion and the heat of the circulating air does not .warm up said second portion as rapidly as the first. portion, means for delivering liquid refrigerant first to said first portion and then to said second'portion, means for controlling the operation of said apparatus in such a manner that frost does not accumulate on said first portion at least part of the time, and means for controlling the flow of liquid and gaseous refrigerant from the first portion to the second portion for causing operation of'said second portion at a low temperature.

22. Refrigerating apparatus comprising, in combination, a cabinet divided into two compartments by an insulating wall, a refrigerant evaporator positioned in one of said compartments for cooling circulating air therein and having a relatively large area exposed to the circulating air in said compartment, a refrigerant evaporator positioned in the other compartment so as to be shielded from the circulating air in the other compartment and having provisions for supporting an ice making receptacle in intimate thermal contact with the refrigerant therein, liquid refrigerant conduit means associated with. said evaporators, means for maintaining said evaporators substantially flooded with liquid refrigerant, and means to control the flow of liquid and gaseous refrigerant from the first named evaporating element to the second named evaporating element for obtaining a pressure differential between said elements.

23. A refrigerating system comprising, in combination, a plurality of evaporators connected in series circuit relation, means for withdrawing gaseous refrigerant from the evaporators and for condensing the gaseous refrigerant and for delivering the same to the evaporators, a liquid feed valve of the type adapted to feed liquid refrigerant from the means at a rate substantially in direct accordance with the rate of accumulation of liquid refrigerant condensed, said liquid feed valve being interposed between the said means and the inlet to the evaporator first to receive liquid refrigerant, and a second valve interposed between the outlet of the first evaporator and the inlet to the next evaporator for controlling the flow of both liquid and gaseous refrigerant from the first to the second evaporator, said second valve including a pressure element for moving the valve, and said pressure element being responsive to the pressure in the first evap orator for supplying refrigerant from the first to the second mentioned evaporator in response to the pressure in the first evaporator.

24. A refrigerating system comprising, in combination, a plurality of evaporators connected in series circuit relation, means for withdrawing gaseous refrigerant from the evaporators and for condensing the gaseous refrigerant and for delivering the same to the evaporators, a high side fioat type valve interposed between the said means and the inlet to the evaporator first to receive liquid refrigerant, and a second valve interposed between the outlet of the first evaporator and the inlet to the next evaporator for controlling the flow of both liquid and gaseous refrigerant from the first to the second evaporator, said second valve including a pressure element for moving the valve, and said pressure element being responsive to the pressure in the first evaporator for supplying refrigerant from the first to the second mentioned evaporator in response to the pressure in the first evaporator.

25. A refrigerating system comprising, in combination, a plurality of evaporators connected in series circuit relation, means for withdrawing gaseous refrigerant from the evaporators and for condensing the gaseous refrigerant and for delivering the same to the evaporators, a liquid feed valve of the type adapted to feed liquid refrigerant from the means at a rate substantially in direct accordance with the rate of accumulation of liquid refrigerant condensed, said liquid feed valve being interposed between the said means and the inlet to the evaporator first to receive liquid refrigerant, and a second valve interposed between the outlet of the first evaporator and the inlet to the next evaporator for controlling the fiow of both liquid and gaseous refrigerant from the first to the second evaporator, said second valve being responsive to the pressure in the first evaporator for supplying refrigerant from the first evaporator to the second mentioned evaporator in response to the pressure of the first evaporator.

LAWRENCE A. PHILIPP.

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