US2114768A - Refrigerating apparatus - Google Patents

Description

April 19, 1938.

L. A. PHILIPP REFRIGERATING APPARATUS Filed' DeG, 8, 1932 ze am A if l'llllllllllllll.

'Illlllll INVENTOR mmafw M.akm

ATTORNEY Patented Apr. 19, 1938 UNITED STATES PATENT OFFICE BEFBIGEBATING APPARATUS land Application December 8, 1932, Serial No. 648,261

4 Claims.

This invention relates to reirigerating apparatus and particularly to the control mechanism for such apparatus.

One of the objects of the invention is to provide a refrigerating system in which the cooling unit normally operates between predetermined temperatures and in which is provided a means responsive to the condition oi the cooling unit to raise the temperature oi the cooling unit to a point at which the accumulated frost melts and thereafter the system is returned to normal operation.

Another object of the invention is to provide a system so constructed and arranged that the accumulation of frost to any predetermined thiclrl ness on a cooling unit will cause the operation of the control mechanism to be temporarily modiiied and produce a single defrostlng cycle during which cycle substantially all of the accumulated frost melts.

A further object of the invention is the provision oi mechanism operable at the will of the user of the machine to render the automatic defrosting mechanism inoperative, so that the machine will operate solely under the control of the normal temperature-responsive mechanism. Such a construction is particularly desirable for use in household refrigerators in which at times it is necessary to keep the machine in normal operation for the purpose of freezing ice or dessert.

Other objects and advantages of the invention will be apparent from the following description and accompanying drawing wherein the single iigure is a diagrammatic representation of a refrigerating apparatus embodying one form of my improved control mechanism partly in elevation and partly broken away.

'In general my invention, which may be applied to any automatically controlled reirigerating apparatus, comprises a mechanism responsive to the temperature of the cooling unit for opening and closing the circuit to a source of power for the compression mechanism, together with a temperature-responsive device located adjacent to but spaced from the cooling unit and operatively associated'with a mechanism arranged to temporarily modify the action of the first named temperature-responsive mechanism.

In the embodiment of the invention herein illustrated there is shown a cooling unit or evaporator III located within an insulated compartment III,- and which is provided with a freezing compartment II for the reception of ice trays I2.

u Evaporated refrigerant is withdrawn from. the

cooling unit I0 through a conduit I3 by means of i a compressor Il wherein the expanded gas is compressed and discharged through a conduit I5 to a condenser I6. The condensed refrigerant passes through a conduit I1 to the header IB of the aforementioned cooling unit IIl and within this header I8 may be located any suitable pressure reducing valve such as a iioat valve (not shown). The compressor is driven by an electric motor I9 through a belt 20.

The operation of the motor and compressor is controlled by a temperature-responsive device 2i comprising a thermostatic bulb 22 located in immediate contact with a wall of the cooling unit IIl and connected by a flexible conduit 23 to a hermetically sealed sylphon bellows 24. The bulb 22, conduit 23 and bellows 24 contain expansible fluid which may be sulphur dioxide, methyl chloride or any other similar and well known medium. One end of the bellows is fixed as indicated at 25, and its outer end 26 moves in response to variations in the pressure of the medium contained within the bellows. The outer end of the bellows is secured to a lever 21, which lever has one of its ends mounted on a fixed pivot 28 and its other end movably secured to a switch operating rod 29. Movement of the rod upwardly is opposed by coil spring 30 secured between the fixed stop 3I and a collar or disc 32. The collar 32 may be mounted in screw threaded relation with the shaft 29 as indicated at 33, so that it may be rotated relatively to the shaft 29 as by means of a pinion gear 34 associated with its peripheral edge, thereby varying 'the tension on the spring 30.

A conventional toggle mechanism 35 carrying at one end thereof a movable contact member 36 is also associated with and operated by the shaft 29. A pair of iixed contact members 31 is provided to cooperate with the movable contact member 36.

In the operation of the control mechanism as hereto described, with the parts in the position shown in the ligure in the drawing, the circuit through the contact members 36 and 31 is broken and the compressor and its driving motor are at rest. When the temperature of the evaporator has increased to a predetermined degree the iiuid contained in the thermostat bulb 22 and the bellows 24 will expand suiiiciently to cause the bellows to move the lever 21 and the rod 29 upwardly against the tension of the spring 30, and when the pressure exerted within the bellows becomes sumcient to overcome the downward force of the spring 30, the rod 29 will move upwardly far enough to cause the toggle mechanism 35 to snap to its downward position and thereby close the circuit to the motor I9 through the contact members 36 and 31. continue to operate until the cooling unit temperature has been lowered to such an extent that the pressure with the bellows 24 and its associated bulb 22 has been reduced to a point where the force of the spring 30 overcomes the pressure exerted by the bellows, whereupon the rod 29 will be moved downwardly to the point where the toggle mechanism will be operated to separate contact members 36 and 31. The adjustment of the collar 32 relative to the shaft 29 to increase or decrease the tension on the spring 3D obviously serves to vary the eifective operating temperature of the switch mechanism.

In order to temporarily modify the operation of the control mechanism which has just been described, so that the cooling unit may be periodically automatically defrosted, I have provided a means responsive to the accumulation of a substantial quantity of frost on the unit for modifying the operation of the compressor. In the embodiment herein shown and described, this means comprises a bulb 38 disposed adjacent to, but spaced a short distance from, the cooling unit. lIfnis bulb, which should be relatively long, is spaced from the cooling unit at a distance at which the accumulation of frost on the unit begins to materially retard the rate of heat transfer from the air to be cooled to the cooling unit, and in tests I have already conducted I have found that a satisfactory operation is obtained by placing the bulb about one-quarter inch from the outer wall of the cooling unit. The bulb 38 is connected by means of a flexible conduit 39 to a sylphon bellows 40, and a suitable expansible iiuid is conned within the bulb 33, the conduit 39 and the bellows.

One end of the bellows is rigidly fastened as indicated at 4i, while the other end 42 is free to contract and expand in accordance with variations in the pressure of the confined expansible fluid. The movable end of the bellows operates against one end 44 of a lever which is pivoted intermediate its ends as indicated at 45. The outer end 46 of this lever bears against an operating rod 41 which is recessed at its lower end as indicated at 48 so as to telescope over the outer end of the rod 29. A coil spring 49 is interposed between the lower end of rod 41 and the collar which is attached to the gear member 32. The rod 41 is provided with a toggle mechanism 50 whereby the rod will move either up or down with a snap action. The movement of the bellows 40 is opposed by an adjustable coil spring 5l.

In the operation of the complete control mechanism herein described the refrigerating apparatus remains under the normal control of the thermostatic bellows 24 and the switch mechanism until the frost on the cooling unit has accumulated to such a thickness that it contacts with and begins to surround the bulb 38. As the frost begins to collect around the bulb it lowers the temperature and consequently the pressure of the expansible medium within this bulb and its associated bellows 40 to a point where the force exerted by the bellows is insufficient to overcome the force of the spring 5|,.whereupon the spring 5I moves the operating lever counterclockwise, causing the end 49 -thereof to bear against the upper end of the rod 41 with sufcient force to deflect the toggle mechanism 50 and thereby cause the rod 41 t0 move downwardly The motor and compressor will with a snap action until the lower end of the rod engages the spring 49 and compresses itagainst the collar 32. It will be obvious that when the rod 41 and the associated spring 49 are bearing against the member 32, the bellows 24 must exert a pressure suilcient to overcome the force of the spring 30, the spring 49 and the two toggle members 35 and 50 in order to permit the closing of the contact members 36 and 31. In other words in order to obtain the necessary pressure within the bellows 24 the cooling unit I0 must heat up to a temperature higher than that at which it normally operates, and it will be apparent that, by properly determining the effective pressure exerted by the rod 41, the toggle 50 and the spring 49, this temperature may be set suiiiciently high to permit the complete defrosting of the cooling unit before the switch contact members 36 and 31 are again closed. When this predetermined high pressure and correspondingly high temperature is reached, the bellows 24 will move the rod 29 upwardly against the force of the spring 30,

the spring 49, and the two toggle members and will eventually force the rod 41 up to a point where the toggle mechanism 5U will throw over, and completely remove the rod 41 from contact with the spring 49. While the cooling unit has been warming to this predetermined defrosting temperature, the expansible fluid within the bulb 33 and the bellows 4U will also become warmer and thus will oppose the force of the spring 5| sufficiently to rock the arm 44 of its operating lever in a clockwise direction and thereby relieve the rod 41 from the force of the spring 5i.

Movement of the member 32 upwardly on the rod 29 to obtain Varying temperature conditions within the evaporator, with the resultant compression of the spring 39, has the effect of shortening the distance through which the rod 41 must move to bring it in contact with spring 49 so that less pressure will be exerted by the springr 49, the rod 41 and its attached toggle member, thereby providing a compensating effect for the increased tension on the spring 3G with the result that the defrosting cut out temperature will lbe substantially constant regardless of the position of the member 32 relative to theshaft 29. In the actual operation of my device I have found that if the main thermostatic control mechanism 2l is set to cut in the compressor at a cooling unit temperature of 28 degrees Fahrenheit and to cut out the compressor at a cooling unit temperature of 19 degrees Fahrenheit, and that if the thermostatic bulb 38 is spaced approximately one-quarter inch from the cooling unit and is set to operate so as to permit the arm 41 to be forced down by the spring 5| when the temperature of the bulb has been reduced by the accumulated frost to approximately 27 degrees Fahrenheit, complete defrosting of the cooling unit is obtained in a single cycle. The bulb 38 may be moved to or from the cooling unit wall so as to Vary the amount of frost which may be permitted to collect, and the operating temperature of the defrosting thermostat may be regulated by varying the tension on the spring 5I.

In order that the automatic defrosting mechanism may be rendered ineiective at the will of the user of the machine, as for example when it is desired that ice or desserts be frozen without any unforeseen interruption, I have provided a pivoted lever member 52 having a handle or knob 53 and so arranged that a. projection 54 provided thereon may be interposed in the path of movement of the end 46 of the operating lever and I thereby prevent any movement of this lever in a counterclockwise direction even though the temperature of the bulb 38 should be reduced by the collection of frost thereon to a point where the spring 5I normally tends to force the rod 41 in a downward direction.

It will be apparent from the foregoing description that I have shown only a diagrammatic embodiment of the invention, and that various structural modiilcations may be made and other forms adopted all coming within the scope of the appended claims.

`I claim:

l. Refrigerating apparatus comprising a cooling unit, means for circulating a refrigerant medium through said unit, pressure operated apparatus responsive to the temperature of said unit for controlling the ilow of said refrigerant medium to maintain normal operating temperatures for the unitl manually operated means for adjusting the pressure operated means to vary the operating temperature of said unit. automatic means responsive to a predetermined condition of said unit for temporarily obtaining a predetermined higher temperature in said unit, and means associated with said automatic means for insuring the attainment of said predetermined higher temperature regardless of the setting of said manually operable means.

2. Refrigerating apparatus comprising a cooling unit. rzeans for circulating a refrigerant medium through said unit, pressure operated ap'- paratus responsive to the temperature of said unit for controlling the ilow of said refrigerant medium to maintain normal operating temperatures for the unit, manually operated means for adjusting the pressure operated means to vary the operating temperature of said unit, automatic means responsive to the accumulation of a predetermined amount of frost on said unit for temporarily obtaining a predetermined higher temperature in said unit, and means associated with said automatic means for insuring the attainment of said predetermined higher temperatemperature range, additional pressure operated means also operative to operate said device .to cause an increase in temperature of said cooling element above said range irrespective of the regulation effort of said first means, said additional means being constructed and arranged so that operation thereof is instigated upon accumulation of a predetermined amount of frost on said cooling element and operation thereof is terminated upon predetermined abnormal increase in temperature of said cooling element and manually operable means positioned for controlling said additional pressure operated means.

4. Refrigeration apparatus including a cooling unit, and apparatus for controlling flow of refrigerant in1 said unit comprising a primary energy control device, means for normally actuating said device including a bellows and a bulb responsive to temperature of said cooling element connected to said bellows, a second bellows, a second bulb spaced from said cooling unit and connected to said second bellows, said first and second bellows acting through common mechanism on said control device, means whereby said second beliows is normally ineffective and is caused to take over actuation of said control device on attaining a low temperature due to accumulation of frost, snap action mechanism associated with said second bellows and a manually controllable locking de- 4o vice associated with said second bellows.

LAWRENCE A. PHILIPP.

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