US1915265A - Thermostat for refrigerating apparatus - Google Patents

Description

June 1933. F. R. BICHOWSKY 1,915,265

THERMOSTAT FOR REFRIGERATING' APPARATUS Filed Dec. 29, 1928 Patented June 20, 1933 UNITED STATES PATENT OFFICE I'RANCIS B. BICHOWSKY, OF WASHINGTON, DISTRICT OI COLUMBIA, ASSIGNOR 1'0 FBIGIDAIRE CORPORATION, OF DAYTON, OHIO, A COBTORATIUU OF DELAWARE THEBMOSTAT 1 R BEFBIGERATING APPARATUS Application filed December 29,1928. Serial No. 329,111.

This invention relates to refrigerating apparatus and more particularly to a refrigcrating system wherein the energy source is controlled by means of a thermostat having energy being controlled by an element with a flexible chamber receiving, pressures from shown.

a fluid medium of such a character that the medium furnishes suflicient operatmg pressure at the low temperatures prevailing during the operation of the system and does not roduce'excessive pressureswhen the system 18 temporarily non-operative. Under certain conditions the fluid medium may be separate from the refrigerant of the system,

Further objects and advantages of the present invention will be apparent from thefollowing description, reference being had to the accompanying drawing, wherein a preferred form of the invention is clearly In the drawing The figure is a view partly diagrammatic and partly-in cross section of a refrigerating system embodying features of this invention. v

A refrigerating system embodying features of this invention may comprise a comressor 2O which delivers compressed re-- rigerant to a condenser 21. The condenser 21 delivers condensed refrigerant to a receiver ors torage reservoir 22. From thence the refrigerant may be delivered by means of a pipe 23 to an evaporator 24. In the evaporator 24 the refrigerant is evaporated and returns to the compressor 20, preferably through a pipe 25 delivering into the'crankcase of the compressor. In this particular embodiment, the system may be of the'nexpansion type, in which case the liquid refrigerant from the pipe 23 passes to an auto matic expansion valve 26 wherein the refrigerant is automatically expanded to a pre-' determined low ressure. The expanded refrigerant may t en pass through a pipe 27 to the evaporator, for instance to the inner coils 28; The coils 28 may form a freezing zone for the reception of trays for forming ice cubes and the like. After passing through the inner coils 28 the refrigerant may pass to the outer air cooling coils 29 and from thence to the pipe 25 and the compressor 20. If desired, the automatic'expansion valve 26 may be provided with an artificial atmosphere formed by the tube 30 and the bulb 31 so that the atmosphere on one side of the diaphragm in the expansion valve 26 may be kept substantially constant, since the bulb 31 may be placed in the space to be refrigerated.

The refrigerating system may be intermittently operated, for instance, by being intermittently driven by'la motor 32, which may be connected by the belt 33 with a flywheel 34 of the compressor 20. The motor 32 may be started and stopped by means of a snap switch 35 which is operated by a flexible chamber 36 connected by tubing 37. with a,"

thermostatic bulb 38 placed adjacent to the evaporator 24. A volatile fluid in the bulb 38 actuates the flexible chamber 36, so that it opens and closesthe electric contacts 39 for making and breaking the electric circuit 40 which supplies energy to the motor 32. This system, as thus far described, may be, though not necessarily of the ty e described in the application of llarry B. ull, Serial No.'183,480, filed April 13, 1927, now Patsent 1,883,920 granted Oct-25 1932 which is merely referred to as an example of a refrigerating system which may be modified to embody features of this invention. It is obvious, however, that other systems may embodyfeatures of this invention. The snap .switch may be, though not necessarily, of

vided with the snap mechanism 53 and with 2 the electrical contacts 39. In this articular embodiment, an adjustable pointe screw 54 acts on the cup-shaped end member 55 of a spring 56. The other end of the spring 56 may be provided with a cup-shaped member 57 engagin with stationary pointed member 58. As t e end of the arm 50 swings up and down, the alignment of the members 58 and 54 is such that a snap action is produced by virtue of the compression of the spring 56 and the alignment of the members 58, 54 causing the spring to reach an intermediate pointv of maximum compression. Other adjustments, such as the spring 60 having an adjustable connection 61 with thearm 50, together with the adjustment 54 enable the snap switch to be so'adjusted that the motor is started and stopped to produce predetermined high and low pressures in the vicinity of the evaporator 24. i

In domestic refrigerators and the like the predominating temperatures in the evaporator at present hover around 10 C. (14 F.) Thus 1t is seen that if the thermostatic bulb 38 should be filled with pure sulphur dioxide, the pressure acting on the flexible chamber 36 would be 0 lbs. gauge. It thus would seem that, at the temperatures when the thermostat should be most-sensitive, that actually the thermostat is providing the least a cunt of pressure. Should the thermostati hulb be filled with methyl chloride, the pressure acting on the flexiblechamber 36 would be sufiicient at temperatures around --10 C. (14 F.). However, should the system remain idle for a long period of time, as during the vacancy of the residence, during transportation of the system, or the like, the temperatures acting on the bulb 38 might rise to some temperature such as 40 C. 104 F.). At this temperature, the pure methyl chloride would exert a pressure of 112 lbsgauge. Thls 13 such an excessive pressure that it has a tendency to distort the members of the flexible chamber 36 and possibly the knife edge contact of .the member 52which is close to the fulcrum point 51.

In order to overcome these various objections, fluids may be so chosen, according to this lnvention, that they may be mutually soluble, non-reacting and at least two may be so chosen that one has a pressure above and the other has a pressure below the pressure necessary to operate the movable control member at the predominant operating temperature of the refrigerating system. Thus amequal mixture of sulphur dioxide and methyl chloride may be made. In a preferred embodiment, the proportions of these substances may be-in the ratio of one mol of sulphur dioxide to one mol of methyl chloswitch. Should the temperature rise to 40 0. (104 F.), this mixture would exert only about.90 lbs. gaugeawhich would be insuflicient to distort the mechanism of the type herein disclosed. Another mixture which is suitable under these conditions is methyl chloride and nori'nal butane in the proportions of two parts of methyl chloride and one part of normal butane. Such a mixture has about 5 lbs. gauge pressure at 10 C.

14 and only 60 or lbs. at 40 C. 104 Variousother mixtures in accordance with the principles herein disclosed may bechosen. Some of the preferred substances for making these mixtures are at least two of the following: sulphur dioxide, methyl chloride, isobutane and the pair ammonia and methylene. In general, it is necessary to obtain at least two mutually soluble and non-reacting fluids, or liquids, in which one has the pressure above, and the other a pressure below, that necessary to operate the movable control member at the predominant operating temperature. The exact desired pressure may be obtained by varying the proportions of the substances so mixed.

While the form of embodiment of the in vention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: 1. In a refrigeration system, control means therefor, said control means comprising a thermostat element containing a mixture of at least two mutually soluble, non-reacting fluids having pressures one above and the other below the pressure necessary to operate said movable control member at a predominant operating temperature of the refrigcrating. system.

2. In a refrigeration system, control means therefor, said control means comprising a thermostat element containing a mixture of at least two mutually soluble, nomreacting fluids having premures one above and the other below the pressure n v-;-: ry to operate said movable control member at the lower operating temperature limit of the refrigerating system.

3. In a refrigeration'system, control means therefor, said control ,means comprising -a thermostat element containing a mixture of sulphur dioxide and methyl chloride.

4. In a refrigeration system, control means therefor, said control means comprising a thermomat element containing a mixture of sulphur dioxide and methyl chloride in the proportions of one mol of sulphur dioxide and one mol of methyl chloride.

5. In a refrigeration system, control means.

therefor, said control means comprising a thermostat element containing a mixture of at least two mutually soluble, non-reacting fluids havin pressures one above and the other below t e pressure necessary tooperate said movable control member at a predominant operating tem rature ofthe refrigerating system, said uid medium containing at least two of the following substances, sulphur dioxide, methylchloride, normal butane, isobutane and the pair, ammonia and methylamine.

6. In a thermostatic control means for refrigerating apparatus in which in order to operate the control means a volatile liquid is used having an insuflicient vapor pressure at the low operating temperatures to proper- 1y actuate the control means, the method of correcting the 'vapor pressure characteristics by adding asecond volatile liquid having a 'higher vapor pressure in a quantity limited so as to prevent the occurrence of excessivevapor pressures/at :high temperatures wh the apparatus is idle, but providing an mcreased vaponpressure at operating tempera tures.

In testimony whereof I hereto aflix my signature.

RANCIS R. BICHOWSKY.

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