US2319498A - Refrigerating apparatus - Google Patents

Description

.May 18, 1943 F. w. GERARD REFRIGERATING APPARATUS Filed Nov. 2o, 1940 n. L 54 4 n, M MV bl. z n n n. 4 l. n

Patented May 18, y 1943 REFRIGERATING APPARATUS Frank W. Gerard, Dayton, Ohio, assig'nor to Geni eral Motors Corporation, Dayton, Ohio, a corporation of Delaware SApplication November 20, 1940, Serial No. 366,442

s claims. (c1. ez-s) This invention relatesv to refrigerating apparatus and particularly `to means for controlling the ow of liquid refrigerant from the refrigerant compressing and liquefying unit t the evaporator.

In many refrigeration applications restrictors have replaced valves for controlling the iiow of liquid refrigerant from the condenser to the evaporator. 'I'he chief reason for this is because of the simplicity of a restrictor which renders the same substantially foolproof to thus reduce service troubles. Restrictors, however, do not accommodate varying refrigeration loads as well as desired. In restrictor type systems use is made of a varying condensing pressure and the cycling of the systm to secure some variation of the systems the restrictor will not produce sufficient throttling of the ow of liquid refrigerant to the evaporator under high temperatures and high refrigerant condensing pressure conditions. An abnormally high condensing pressure causes too liquid Iiow in accordance with varying loads.` `However, it has been found that in ordinary much liquid refrigerant to be forced through a capillary passage 0f a restrictor and as a result thereof the evaporator becomes full of liquid refrlgerant which slopes or flows therefrom into the suction line and causes this line to become frosted. Operation of a refrigerating system under this condition is rather ineiiicient and highly undesirable.

It 'is an object of my invention to reduce the iiow of liquid refrigerant through a capillary. passage of a restrictor under, high temperature and high pressure conditions to prevent an accumulation of an `excessive amount of liquid refrigerant in the evaporator.

Another object of my invention is to provide means for changing the cross-sectional area of a capillary passage of a restrictor of a refrigerating system which means is rendered eective automatically in response to temperatures exteriorly of the food storage compartment to be cooled by the evaporator of the system A further object of :ny inventionis to provide a 'restrictor for a. refrigerating system with a continuously open capillary refrigerant restricting passage of great length in proportion to its cross-sectional area that is of a predetermined restriction to the now of liquid refrigerant to the evaporator under normal ,temperature andpressure conditions and which restriction thereof is reducing the ow of liquid refrigerant therethrough in its passage to the evaporator.

In carrying out the foregoing objects it is a still further and morespeciiic object of my invention to provide a restrictor of avrefrigeratingsystem with an insert member that has a greater coefficient of expansion and contraction than walls of the restrictor in which it is confined and which insert is provided with a continuously open capily lary refrigerant restricting passage, the crosssectional area of which is reduced automatically by its expansion within the confinement of walls 'of the restrictor due to an increase in temperature outside the compartment being cooled by the system.

Further objects and advantages o'f the present Fig. l and constructed in accordance with my .diameter of the refrigerant restricting capillary passage; and

Fig. 4 is a view similarto Fig. 3 showing the diameter of the refrigerant restricting capillary passage diminished.

increased under-high temperature conditions for In Fig. 1 of the drawing I have shown a refrigerating apparatus of the household type comprising a cabinet I0 having insulated walls II forniing a food storage compartment I2 therein and including a closed refrigerant circulating system or circuit associated' with the cabinet. The closed refrigerating system includes a refrigerant compressing and liquefying unit comprising a sealed motor-compressor I4 for compressing refrigerant and for forwarding the compressed refrigerant toy a condenser I5 where the compressed refrigerant `is liquefied and collects therein. From the condenser |5 the liquid refrigerant is forwarded through a supply conduit I6 to a restrictor element I'I,4 and through a small, preferably'insu- V I8 to an` evaporator I9. The

the food compartment I2 which is to be cooled and the restrictor element I1 controls the now oi?- liquid refrigerant thereinto. Liquid refrigerant vaporizes within the evaporator I9 under reduced pressure and the evaporated refrigerant returns to the compressor through a suction conduit 2|. In. order to provide for intermittent operation of the motor-compressor I4 a thermostatic switch (not shown), actuated in response to the refrigerating effect produced by evaporator I9, may be connected into the electric circuit leading to the motor-compressor I4. The method of actuating such a switch. by a thermostat bulb and the construction of the switch itself is now conventional and forms no part of the subject matter of the present application. The restrictor element, generally represented by the reference character I1, of the refrigerating system is, in the present illustration, mounted exteriorly of the insulated walls II of compartment I2 and preferably Within the outer sheet metal walls of cabinet I. The restrictor of the present invention is variable in response to its environment temperature`in a manner and for a purpose to be hereinafter more fully described. For example, the restrictor'element I1 in the present disclosure is exposed to temperatures outside the compartment I2 and of the room Within which the refrigerating apparatus is located. Motor-compressor i4 and condenser I5 of the refrigerant compressing and liquefying unit of the refrigerating system may be mounted in a machine compartment of cabinet I located below the food compartment I2.

The restrictor element I1 better shown in Fig. 2 includes a metal housing 25 having a large round bore 26 therein threaded at one end as at 21 and provided at its other end with a threaded boss or projection 28. A small bore 29 extends from the inner wall of bore 26 through the threaded boss 28. The pipe or conduit I8, which leads from the restrictor to the evaporator of the refrigerant circuit, is secured to element I1 by a nut 3l threaded upon the boss 28. I place a non-metallic round elongated plug-like member or means 33, having an opening 34 provided centrally thereof, within the bore 26 of housing 25 and locate a metal Washer 36, having a hole 31 centrally thereof, at one end of member 33. An adjustable metal clamping gland 39, having a hole 4I centrally thereof, is threaded as at 42 upon the threads 21 of housing 25 and abuts the Washer 36. Gland 33 is provided with a key or screwdriver slot 44 to permit adjustment thereof Within the bore 26 and against Washer 36. A nut 45 threaded into the threads 21 of housing 25 has a gasket 46 disposed under a shoulder formed thereon and clamped against the end portion of housing 25 to seal the same against leakage of refrigerant at this point. Nut 45 is also provided with a threaded projection or boss 41 which receives a nut 43 for securing the liquid refrigerant supply pipe or conduit I6 to the element I1. An opening 49 extends through nut 45 and its boss 41 to permit now' of refrigerant from pipe I6 into the element I1.

The opening 34 located centrally within member 33 forms.a continuously open substantially capillary passage Within element I1 preferably, although not necessarily, of great length in proportion to its cross-sectional area so as to serve as the sole means for controlling the flow of liquid refrigerant from the Vcondenser I to evaporator I9. The member 33 is preferably formed of a resilient rubber-like material, such as a compound which includes a polymer of chloroprene or neoprene, of the type sold under the trade name of Duprene." The material of member 33 as constructed is resistant to the refrigerant and oil used in the refrigeratlng system and has the characteristic of being expansible and contractible in response to changes in temperature thereof. The member 33 has a greater coeicient of expansion and contraction than the metal Walls of housing 25 of restrictor element I1 and since, as before stated, the element I1 is mounted outside the compartment I2, member 33 therein is subject to its environment temperatures.

After placing plug-like member 33 within the bore 26 of housing 25 the member 33 is confined by the one flat end wall and round side Wall of the bore and at its other end by the washer 36. This confinement of member 33 within element I1 permits'the adjustable gland 33 to be tightened against washer 36 to rmly clamp member 33 Within the restrictor housing 25. The elongated hole 34 in member 33 is set, by the clamping gland 39, to a predetermined diameter or cross-sectional area to offer the proper or a predetermined resistance to the flow of liquid refrigerant through the restrictor element I1 in lts passage to the evaporator under normal voperating temperature conditions. The confinement of member 33 by Walls of housing 25 and the predetermined clamping thereof within the bore 23 maintains the proper cross-sectional area of the hole 34 for normal operating temperatures as balanced against the normal temperature of refrigerant flowing through the restrictor. However, this confinement of member 33 also causes the diamleter or cross-sectional area of the restricted refrigerant passage 34 to be reduced when the temperature of member 33 is increased above normal room temperature or increased when the temperature of the room is decreased. Since a rise in temperature of member 33 creates expansion thereof its method of confinement causes the same to expand in a'direction toward the passage 34 to thereby reduce the diameter thereof substantially uniformly along its length. Conversely, a drop in the temperature of member 33- creates contraction thereof to cause enlargement of the cross-sectional area of the capillary passage 34. 'I'his characteristic of member 33 is utilized for varying the amount of liquid refrig erant flowing through the restrictor element to the evaporator in response to environment temperatures about element I1.

The refrigerant restricting passage 34 of element I1 may normally offer the proper resistance to the fiow of refrigerant to the evaporator of the refrigerating system within the ordinary temperature ranges maintained in the room in which the refrigerating apparatus is located in accordance with normal pressures in the system which affect the ow of refrigerant therethrough. However, an abnormal rise in temperature Within the room, such as a period of several days of Very hot Weather during the summer, Will cause the temperature and consequently the pressure of refrigerant .in the condenser to increase. Without some means for varying the size of the capillary passage of the restrictor this increased pressure of refrigerant within the condenser will force too much liquid refrigerant through the passage and into the evaporator. My-invention eliminates the difficulties hereinbefore pointed out in that Whenthis abnormal high temperature occurs the refrigerant restricting passage of the restrictor element automatically offers more re-v striction to the refrigerant now to thereby pre- I pansible and contractible `in- .temperature exteriorly of said compartment,

vent too greatv a flow of liquid refrigerant into the evaporator. The abnormal high temperature is transmitted through the metal walls of the element I1 to member 33 therein and this higher temperature will cause expansion of member 33. Due to the confinement of member 33 within the element IT as herein disclosed, the expansion thereof is in a direction to diminish the diameter or cross-sectional area of passage 34 and its smaller diameter, see Fig. 4, as compared to its normal diameter, seeFig. 3, affords greater resistance'to the flow of refrigerant from the condenser to the evaporator to thereby prevent the higherpressure in the system from circulating too much refrigerant through the restrictor. In other words, as the temperature exteriorly of the refrigerated food compartment increases abnormally this temperature affects the restrictor membersimultaneously with the attending increase in pressureof refrigerant in the condenser and causes a reduction in the size or crosssectional area of the capillary passage of the restrictor, The additional restricted flow of liquid refrigerant to the evaporator counterbalances .the increase of refrigerant pressure Within the system to thereby provide eficent operation of the system without the dimculties heretofore enumerated.

Irrespective of the location of the restrictorl element, a drop in the temperature surrounding same causes the capillary passage forming element thereof to contract. Contraction of this member enlarges the cross-sectional area of the refrigerant restricting passage and permits sufflcient liquid refrigerant to flow into the evaporator to provide efficient refrigeration within the food storage compantment of the refrigerator cabinet under low temperature conditions, which conditions might otherwise diminish the flow of refrigerant to the evaporator to such an extent that the evaporator would be starved of liquid cooling said compartment, a refrigerant compressing and liquefying unit and a restrictor ele-rment exposed to temperatures exteriorly of said compartment, a member confined within walls of said restrictor element and having' a greater coefficient of expansion and contraction than the walls thereof, said member having an opening therein forming a continuously open capillary passage therethrough of great length in proportion to its cross-sectional area for controlling the flow of liquid refrigerant from said unit to said evaporator, and said member being expansible `and contractible in response to changes in temperature exteriorly of said compartment and be, ing so conned within the walls of said restrictor element that its contraction or expansion varies the cross-sectional area of said capillary passage.

3. A refrigerating apparatus comprising, a cabinet having a compartment therein to be cooled. a closed refrigerant circuit associated with said cabinet, said circuit including an evaporator for cooling said compartment, a refrigerant compressing and liquefying unit and a restrictor element exposed to temperatures exteriorly of said compartment, an elongated plug-like member within said restrictor element and having formed centrally therein a continuously open capillary passage of great length in proportion to its crosssectional area for controlling the flow of liquid refrigerant from said unit t0 said evaporator, said member being formed of a material that is expansible and contractible in response to changes in temperature exteriorly of said compartment, and said mem-ber being so confined by walls of said element that expansion and contraction thereof is in a direction to vary the cross-sectional area of said capillary passage.

4. A refrigerating apparatus comprising, a cabinet having a compartment therein to -be cooled,

refrigerant. Thus, in the present disclosure the y member Within the restrictor element forms the liquid refrigerant restricting means as well as forming its own ladjustment thereof in response to the environment temperature of the element.

While the form of embodiment'of the invention as herein disclosed, constitutes a preferred form,

it is to be understood that other forms might be y adopted, al1 coming within the scope of the claims which follow.

What is claimed is as follows:

l. A refrigerating apparatus comprising, a carbinet having a compartment therein to be cooled, a closed refrigerant circuit associated with said cabinet, said circuit including an evaporator for cooling said compartment, a refrigerant compressing and liquefying unit and a restrictor element exposed to temperatures exteriorly of said compartment, means withinsaid restrictor element and forming a continuously open capillary passage therethrough of great length in prop0r' tion to its cross-sectional area for controlling the ow of liquid refrigerant from said unit to said evaporator, said passage 'forming means being exin response to changes inet having a compartment therein to be cooled,.

a closed refrigerant circuit associated with said cabinet, said circuit including an evaporator for cooling said compartment, a, refrigerant compressing and liquefying unit and a restrictor element exposed to temperatures exteriorly of said compartment, an elongated plug-like member Within said restrictor element and having formed centrally therein a continuously' open capillary passage of great length in proportion to its crosssectional area for controlling the flow of liquid refrigerant from said unit to said evaporator, said member being formed of a resilient non-metallic material having a greater coefficient of expansion 'and contraction than walls of said element, and

said member being expansible and contractible in response to changes in temperature exiteriorly of said compartment and so confined Within the Y walls of said element that its expansion and contraction is in a direction to vary the cross-sectional area of said capillary passage.

5. A refrigerating apparatus comprising, a cabinet having a. compartment therein to be cooled. a closed refrigerant circuit associated with said cabinet, said circuit including an evaporator for cooling said compartment, a refrigerant compressing and liquefying unit and a restrictor element exposed to temperatures exteriorly 4of said compartment, an elongated member confined within walls of said restrictor element and having a greater coefficient of expansion and contraction than the walls thereof, said elongated m'ember having a continuously open capillary passage centrally thereof of great length in a closed refrigerant circuit associated with said l cabinet, said circuit includirg an evaporator for proportion to its cross-sectional area for controlling the flow of liquid refrigerant from said unit to` said evaporator, said member being expansible and contractible in response to changes in temperature exteriorly of said compartment. and said elongated member being s0 confined within the walls of said restrictor element that its contraction and expansion occurs substantially uniformly along the length thereof in a direction to vary the cross-sectional area of said capillary passage.A

6. A refrigerating apparatus comprising, a cabinet having a compartment therein to be cooled, a closed refrigerant circuit associated with said cabinet, said circuit; including an evaporator for cooling said compartment, a refrigerant compressing and liquefying unit and a restrictor element, means conned within walls of said restrictor element and having a continuously open v substantially capillary passage of great length in proportion to its cross-sectional area extending therethrough for controlling the ow of liquid refrigerant from said unit to said evaporator, said passage forming means having a greater coeflicient of expansion and contraction than Walls of said restrictor element, and said passage forming means being so confined within the Walls of said element that its expansion and contraction therein in response to environment temperaturel changes varies the cross-sectional area of said capillary passage.

7. A refrigerating apparatus comprising, a cabinet having a compartment therein to be cooled, a closed refrigerant circuit associated with said cabinet, said circuit including an evaporator for cooling said compartment, a refrigerant compressing and liquefying unit and a .restricter element, an elongated plug-like member confined within walls of said restrictor element and having formed therein a continuously open capillary passage of great length in proportion to its cross-sectional area for controlling the ow of liquid refriger nt from said unit to said evaporator, said passage forming member having a greater coeficient of expansion and contraction than walls of said restrictor element, and said passage forming member being so coniined within the walls of said element that its expansion and contraction in response to environment temperature changes varies the cross-sectional area of said capillary passage.

8. A refrigerating apparatus comprising, a cabinet having a compartment therein to be cooled, a closed refrigerant circuit associated with said cabinet, said circuit including an evap orator for cooling said compartment, a refrigerant compressing and liquefying unit and a restrictor element, a. non-metallic member confined V within walls of said restrictor element and having formed therein a continuously open substantially -capillary passage of greater length than its cross-sectional area .for controlling the flow of liquid refrigerant from said unit to said evaporator, said passage forming member having a greater coeflicient of expansion and contraction than walls of said restrictor element, and said non-metallic passage forming member being so conned by the walls of said element that its expansion and contraction therein in response to environment temperature changes is in a direction to vary the cross-sectional area of said capillary passage. FRANK W. GERARD.

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