US2208267A - Refrigerating apparatus - Google Patents

Description

July 16, 1940. R. J. RIDGE REFRIGERATING APPARATUS Filed Feb. 17

INVENTOR Raymond. J RIO 99 BY ATIV'OR Y Patented July 16, 1940 PATENT OFFICE 2,208,287 REFRIGERATING ArrAaA'rUs Raymond J. Ridge, Lansdowne, Pa., asslgnor to Westinghouse Electric 3.; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 17, 1939, Serial No. 256,889

9 Claimsq (Cl. 62-4) My invention relates to refrigerating apparatus and has for an object to provide improved apparatus of this kind.

A further object of the invention is to maintain 5 the mean temperature of the media in a refrigerated zone at a substantially constant value irrespective of changes in the temperature of the ambient atmosphere and the different rates of heat leakage into the zone which accompany 10 variations in the temperature of the ambient atmosphere.

A further object of the invention is to provide improved means for adjusting the control mechanifim of a refrigerating machine in response to 15 changes in temperature of the ambient atmosphere whereby the mean temperature of the cooling element is increased and decreased with respective decreases and increases in temperature of the ambient atmosphere.

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. 1 is a diagrammatic view of a refrigerator controlled in accordance with my invention; and,

Fig. 2 is an enlarged view of a detail shown in Fig. 1.

Reference will now be had to the drawing wherein I have shown my invention applied to a conventional refrigerator of the domestic type and including a cabinet structure It having insulated walls H for defining a zone or cooling chamber l2. A suitablHlement such as, for

example, a refrigerant evaporator I3 is employed for abstracting heat from the air in the chamber Refrigerant vaporized in the evaporator I3 is withdrawn therefrom through a conduit II by i means of a refrigerant condensing unit, generally indicated at i5, and including a compressor l6 driven by an electric motor IT. The withdrawn vapor is compressed to a relatively high pressure by the compressor l6 and is delivered to a condenser it through a conduit l9. Cooling of the condenser may be eflected in any well understood manner such, as for example, by means of a fan 2i driven by an electric motor 22. The motor I! may be energized from a suitable source of electrical energy (not shown) through line conductors L1 and In. The high pressure vapor delivered,.to the condenser I8 is cooled and condensed'and the liquefied refrigerant is conveyed -to the evaporator it through a conduit 23 having type, and generally shown at 25. The thermostat 25 responds to the temperature of the evaporator l3 and includes an expansible bellows 26 that is connected by a tube 21 to a bulb or reservoir 29, the latter being secured in heat transfer relation with a suitable portion of the evaporator l3. The bulb 29, bellows 26 and tube 21 preferably contain a volatile fluid, the pressure of which increases and decreases with respective increases and decreases in the temperature of the bulb 29. The thermostat 25 includes a switch 29 which is opened and closed, respectively, as the temperature of the bulb 28 attains predetermined low and high values. As shown, the bellows 26 operates a lever 3| that is connected to the switch 29 by an over-center spring 32 or other suitable quick-make, quick-break device. A spring 33 0pposes expansion of the bellows 29 and may be adjusted by a suitable adjusting device shown at 34 whereby the mean temperature of the evaporator l3 may be varied.

The insulating walls H of the cabinet structure l0 may be of conventional construction and defined by spaced inner and outer shells I la and l lb having suitable, heat insulating material Hc therebetween. As the construction of cabinets of the type shown at I0 is well understood in the art, no further description of the same is deemed necessary.

The refrigerating machine described in the foregoing is of the compressor-condenser-expander type, but it will be understood that other suitable forms of refrigerating machines may be controlled in accordance with my invention. As the operation of a refrigerating machine of this type is well known, no detailed description of its operation is deemed necessary other than to say that, as the temperature of the bulb 28 increases to a predetermined value, the thermostat 25 closes the switch 29 for energizing the motor I? 7 whereby operation of the condensing unit I5 is started. Opening of the thermostat switch 29 in response to asecond predetermined value termicontainer 36 of suitable form has its upper end portion 31 connected in heat transfer relation with the thermostat bulb 28 and its lower end portion 38 disposed in heat transfer relation with the ambient atmosphere exterior of the refrigerated zone l2. Preferably, the lower end 38 is secured to the outer shell llb which presents a large surface to the outside atmosphere so that its temperature closely followsvariations in temperature of the ambient atmosphere. The container 36 encloses a suitable charge of volatile fluid, as best shown in Fig. 2, and the arrange- V ment is such that, as the fluid is condensed, it flows by gravity to the lower end portion 38, As

the tube portion 38 is relatively warm, it defines a vaporizing portion and, conversely, the relatively cool portion 31 of the tube'defines a condensing portion for the fluid vaporized in the Portion 38. Accordingly, there is a transfer of heat from the portion 38 of the tube to the portion 31 thereof; the latent heat of vaporization of the fluid being imparted to the cold thermostat bulb 28 as the fluid condenses. The rate of vaporization and heat transfer is a function of the temperature of the ambient atmosphere, so that during periods of high ambient temperature,

heating of the bulb 28 is effected at a high rate (Q and, conversely, during periods of low ambient temperature, heating of the bulb is at a relatively low rate.

Operation As shown in the drawing, the thermostatic switch 29 is open so that the compressor unit I5 is inactive. At this time the temperatures of the media in compartment l2 and of'the evaporator l3 increase due primarily to the leakage of heat through the insulated walls I I. The temperature of the thermostat bulb 28 increases due to the increase in temperature of the evaporator I3 and because of the heat imparted thereto by the condensing fluid in the container 36. When the bulb 28 has been heated to a predetermined temperature, the thermostatic switch is closed and circulation of refrigerant to the evaporator I3 is initiated.

. Cooling of the evaporator is effected by the vaporization of refrigerant therein and heat is abstracted from the air in the chamber l2. Cooling of the thermostat bulb is effected and, when it has been depressed to a predetermined temperature, the thermostatic switch is opened for terminating circulation of refrigerant through the evaporator l3.

The operation described heretofore is for a given outside or ambient temperature. Assuming an increase in outside or ambient tempera ture, the rate of heating of the bulb 28 by the fluid in the container 36 is increased. Accordingly, the temperature of the bulb 28 is increased to the value at which starting of the condensing unit I5 is initiated when the temperature of the evaporator I3 is at a lower value than in the cycle of operation described heretofore. Also, the tern;- perature of the evaporator l3 must be depressed to a lower value than in the cycle of operation described heretofore in order to compensate for the added heat flow to the bulb during operation of the apparatus or when the temperature of the bulb 28 is being depressed to the value at which circulation of refrigerant is terminated.

I, A decrease in ambient temperature effects an operation which is the reverse of that effected by an increase in ambient temperature. A decrease in ambient temperature reduces the amount of heat imparted to the bulb 28 by the fluid in the container 36 so that the evaporator temperatures at the time of opening and closing of the switch 29 are relatively high.

It will be apparent from the foregoing description of operation that during periods when the ambient temperature'and the rate of heat flow into the zone l2 are relatively h the evaporator I3 is operated at a lower mean temperature in order to compensate for this increased load. Conversely, when the ambient temperature and rate of heat flow into the zone l2 are relatively low, the evaporator is operated at a higher mean temperature, whereby the reduced rate of heat leakage into the box is compensated for.

As the operation of the control system described heretofore is dependent upon the relative rate of heat transfer from the container 36 to the thermostat control bulb 28 and from the bulb 28 to the evaporator l3, any desired relation between the temperature of the refrigerated zone and the ambient atmosphere may be obtained by varying the amount of thermal contact between these elements. The thermal contact or heat transferred between the elements may be such that the temperature of the air in the zone I2 is reduced as the temperature of the ambient atmosphere increases and vice versa. This may be desirable in order to compensate for different service loads caused by opening the cabinet door and by cooling food products from different initial temperatures.

While I have shown the vaporizing portion 33 of the container 36 connected to the outer shell Mb, it will be understood that it may be disposed otherwise in'heat exchange relation with the ambient atmosphere. Furthermore, my invention broadly contemplates the employment of the outer cabinet shell as a heat source, the temperature of which varies with ambient temperature, and the transfer of heat in any manner from the shell to the thermal responsive control member.

The specific form of refrigerant circulating machine which I have disclosed is shown by way of example and it will be understood that other forms of refrigerating machines may be controlled equally well in accordance with the invention. Furthermore, forms of thermostats other than the fluid or gas type may be compensated in accordance with the invention.

While I have shown my invention in but one form, it will be 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 imposed by the prior art ing means for abstracting heat from said zone,

means for circulating refrigerant through the cooling means, thermostatic means for initiating and terminating operation of the circulating means in response to predetermined respective high and low temperatures of the cooling element, means for adjusting at least one of said temperatures in response to the temperature of a of means defining a zone to be refrigerated, cooling means for abstracting heat from said zone, means for circulating refrigerant through the cooling means, thermostatic means for controlling operation of said circulating means and including an element responsive to the temperature of the cooling means and means for imparting heat to said element at rates varying with the temperature of the ambient atmosphere exterior of said zone, said last-named means including a container and a volatile fluid therein, said container having a fluid vaporizing portion disposed in heat transfer relation with said ambient atmosphere and a fluid condensing portion disposed in heat transfer relation with said temperature responsive element.

3. In refrigerating apparatus, the combination of means defining a zone to be refrigerated, cooling means for abstracting heat from said zone, means for circulating refrigerant through the cooling means, thermostatic means for controlling operation of said circulating means and including an element responsive to the temperature of the cooling means and means for imparting heat to said element at rates varying with the temperature of the ambient atmosphere exterior of said zone, said last-named means in- 'cluding a container and a volatile fluid therein, said container having a vaporizing portion and a condensing portion disposed for the gravitational flow of condensed fluid from the c on densing portion to the vaporizing portion, said vaporizing and condensing portions being disposed, respectively, in heat transfer relation with the ambient atmosphere and with said temperature responsive element.

4. In refrigerating apparatus, the combination of a cabinet structure defining a chamber to be refrigerated, a cooling element for abstracting heat from the media in said chamber, means for circulating refrigerant through the cooling element, means'responsive to the temperature of the cooling element for controlling the operatlon of said refrigerant circulating means, and means for transferring heat directly from a portion of said cabinet structure to said temperature responsive means.

5. In refrigerating apparatus, the combination of an insulated cabinet structure having spaced inner and outer shells, said inner shell defining a chamber to be refrigerated, an evaporator disposed for abstracting heat from the media in said chamber, means for circulating refrigerant through said evaporator, means responsive to predetermined high and low temperatures of the evaporator for respectively initiating and temiinating operation of the circulating means, and means for transferring heat directly from a portion of said outer shell to the temperature responsive means, whereby the temperatures of the evaporator at which the circulating means is started and stopped are increased and decreased respectively as the temperature of said portion of the outer shell is decreased and increased.

6. In refrigerating apparatus, the combination of means defining a zone to be refrigerated, an evaporator for abstracting heat from the air in said zone, means for circulating refrigerant through the evaporator, a thermostat for controlling the operation of the refrigerant circulating means and having a temperature responsive element in heat transfer relation with the evaporator, a container for a heat transfer medium and having an upper end thereof disposed in heat transfer relation with said temperature responsive element and the lower end thereof disposed in heat transfer relation with the ambient atmosphere exterior of said zone.

7. In refrigerating apparatus, the combination of an insulated cabinet structure having spaced inner and outer shells, said inner shell defining a chamber to be refrigerated, a cooling element disposed for abstractingheat from the media in said chamber, means for circulating refrigerant through said cooling element, a thermostat for controlling the operation of the refrigerant circulating means and having a temperature responsive element disposed in heat transfer relation with the cooling element, a container for volatile fluid and having an upper end thereof disposed in heat transfer relation with said temperature responsive element and the lower end thereof disposed in heat transfer relation with the ambient atmosphere exteriorly of said zone.

8. In refrigerating apparatus, the combination of an insulated cabinet structure having spaced inner and outer shells, said inner shell defining a chamber to be refrigerated, an evapo-. rator disposed for abstracting heat from the air in said chamber, means-for circulating refrigerant through the evaporator, a thermostat controllingoperation of said refrigerant circulating means and having a temperature responsive element disposed in heat transfer relation with the evaporator, a container for a volatile fluid having the upper end thereof disposed-in heat transfer relation with said temperature responsive element and the lower end thereof connected to said outer shell, the lower end of the container defining a vaporizing portion and the upper end thereof defining a condensing portion.

9. In refrigerating apparatus, the combination of a chamber, a cooling element for abstracting heat from the media in said chamber, means for circulating refrigerant through the cooling element, a thermostat on and in heat exchange relationship with the cooling element, saidthermostat controlling said refrigerant circulating means to start the circulation of refrigerant when the temperature of said thermostat rises above a predetermined limit and to stop said circulation when the temperature of the thermostat drops below a predetermined limit, and a heat conducting path of limited capacity for conducting heat from the atmosphere ambient said chamber to said thermostat whereby the control of said thermostat on said refrigerant circulating means acts to decrease the average temperature of the cooling element when the temperature of the ambient atmosphere increases.

RAYMOND J. RIDGE.

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