US2587363A - Controlling device for refrigerator systems - Google Patents

Description

Feb. 26, 1952 H. c. MILLER CONTROLLING DEVICE FOR REFRIGERATOR SYSTEMS Filed Feb. 16, 1949 INVENTOR.

Ha Ward 6/ 1 2' Z Z67.

7AM p A/ ag/2F I A i My 0 Z ATTORNEY Patented Feb. 26, 1 952 OFFICE CONTROLLING DEVICE REFRIGER ATOR SYSTEMS Howard C. Miller, New York, N. Y.

Application February 16, 1949, Serial N 0. 76,840

' 8 Claims. (01. 62--8) This invention is an improvement in controlling devices; and particularly controlling devices for refrigerating systems of the compression and evaporation type.

An important object of my invention is to provide a thermostatic controlling device that is efficient and certain in operation, and with the thermostatic element manually charged or self-charging upon installation, so that it does not have to be charged separately or in advance to prepare it for mounting in the system of which it is a part. It therefore contains the same refrigerant as the system, is very sensitive, fully responsive only to changes within the system and normally unaffected by conditions outside of the same.

A further object is to provide a simpleand practical thermostatic controlling device that can beeasily incorporated into the system, is strong, tight, durable, virtually proof against damage by accidents, and so constructedthat it can be easily and quickly repaired if a leak occurs, merely by replacement of the principal element therein.

Another object is to provide a refrigerant controlling device capable of acting at a comparatively smaller difference between the pressure in its own thermal element and the pressure in the system, thereby increasing the evaporator coil capacity.

' A still further object is to provide. a thermostatic refrigerant controlling device containing a thermal element into which, after installation in a system, a gaseous charge of refrigerant is forced automatically at a limited pressure, proper and best suited for that individual system; such limited charge having the efiect of preventing an overload on the compressor and motor during the initial period of the running cycle; and any damage during the idle period, especially when installed under abnormal conditions so that the thermal device is exposed to high temperature outside atmosphere. I

The nature and advantages of the invention are fully described herein and the novel features are pointed out in the claims. 'But this disclosure is by way of example only and I may vary the details of the construction illustrated, with.-.

out departing from the general the invention is embodied On the drawings, Figure 1 shows inoutline tion system containing my invention;

design in which.

Figure 2 shows in section a'modification ofv my controlling device; and

part of a refrigera- Figure 3 a further modification.

An expansion or evaporation coil is indicated at I. It is supplied with refrigerant through a pipe joined to a connecting element or coupling 2 that is screwed into tight union with the ex pansion valve casing 3. The liquid refrigerating medium flows into the coupling 2 and through the casing to the coil I, where it starts to expand and evaporate into a gas, and the opposite end or outlet of this coil is joined to a coupling 4 to which is joined thereturn connection or suction pipe that conducts the gaseous refrigerant back to the compression pump. In the easing 3 is a valve 5, which cuts off communication when closed between the supply pipe and the coil I. The valve is engaged by a compression spring 6 that tends to hold it against its seat, and the stem 1 of this valve is connected to a diaphragm 8, or it may just make contacttherewith.

The valve 5 operates in a well-known manner to admit the refrigerant to the coil I as required. The casing has a hollow boss on its exterior and the diaphragm is secured against the outer rim of this boss by a, screw cap 9. This cap 9 is coupled to a pipe II] by a soldered or threaded connection. The pressure space 29 within the boss under the cap 9 permits movement of the diaphragm 8, and when the latter is forced inward by an excess of pressure above it, the valve 5 is opened. The force of the spring 6 is regulated by a screw stem 1 l in the casing 3, the stem projecting from the casing and being covered by a screw cap l2. Leakage is prevented by the gland Packing 32, compressed by the threaded nut 33.

. The pipe In is united to the coupling t by a soldered connection, or a threaded connection, as desired. The coupling 4 has the form of a T or other convenient shape with a short stem represented by a boss [3 enclosing a chamber 39, with an aperture at its inner end or bottom and communicating with the bore of the coupling 4. The bottom has an annular shoulder [4 which serves as a seat for a member l5 having a rim I6 resting on the shoulder l4 and making sealed or leakproof contact therewith. The edge of the shoulder may have the form of a rib in relief, so that the rim I6 can engage it panded end 20 of the pipe Ill.

tobetter advantage. A cap I! is screwed on to the boss I3 and this cap has a neck l8 with a duct l9 extending therethrough. The outer end of the neck is conical and over it fits the ex- The connection is completed by means of a cap or coupling nut 2! which binds the end of the pipe on the neck. A spring 22 in the boss 13 presses against the cap I! at one end and upon the member l at the other and holds the latter against the seat [4. Opposite the member 15, the bore of the coupling 4 may be provided with a baflie projection 23.

The casing 3 with the valve 5 and diaphragm 8 therein is a well ,known unit and, except for the upper thermostatic portion, forms no part of this invention; which relates chiefly to the coupling 4 and the thermal device or unit which consists of the heat exchanging or transmitting member [5, the thermal chamber 39, the=connecting pipe Ill, the pressure space 29, and the-diaphragm 8; or, in place of diaphragm 8, afiexible metal bellows that has a similar purpose and function as the diaphragm 8. fl l'i'emonstruction and operation details described herein relate mainly to the application of the thermal device to the so-called thermostatic expansion valve of the diaphragm type, but -iti's equally applicable to the thermostatic expansion valve 'of the bellows type, "and also to "o'thehv'arieties of controls,switches and safety devices.

Inmany ordinary refrigerating systems oft-his kind, the pipe iilleading-fromthe casing 3termihates in a bulb 'which is 'secured to the *outside of the coil l adjacent the-suction-or=outlet end by a bolted metal clamp, said bulb, pipe 10 and the pressure space t9 having previously been evacuated of air, charged with a certain refrigerant at a fixed predetermined --pressu-re,-closed, and sealed by soldering in "the -manufacturing process. With-my inventionall of-these-processes are unnecessary, making for e'conomy "in "production, and there is no external bulb which often causes less efficient and=responsiveoperationbecause the bulb is subject to conditions outside the system as well-as within it.

The thermal device can never contain -the wrong refrigerant, which should always be the same as in the system proper, because itis not pre-charged before installation. 'W-hen'firs't connected, and refrigerant is introduced into the 4 coil l and coupling 4, the increased pressure raises the member I5 off the seat [I allowing gas to enter thermal chaniber 3-9 and -'-pass up through pipe I 0. Then, n the-purge or vent plug 36 is loosened, *the air that was the-thermal devicepasses out, and when plug afi -is retig-htened, the thermal -element is filled with gas at a pressure s'lightly less than that in coil I, the --difference being equal to the light pressure of spring 22.

In most -'compress-ion systems of this type, the operation of the compressor unit is controlled by a pressure control switch, said switch starting the motor when the desiredmax'imum pressure is reached in coil :Lcoupling 4, and -'return line 25. When the-compressor starts-a reduction in pressure occurs in return-line 2'5,*coupl-ing 4, coil 1, and easing 3, and onthe inner su-rface of diaphragm 8, but the pressure inthe'thermal device and on the outer surface -of-diaphragm 8 does not immediately drop, but remains --at'the same level, which is nearly equaltothem-aximum, or starting pressure of the system. Thus an excess of pressure is produced on the outer surface of the diaphragm 8, and when this excess pressure overcomes the opposing pressure ofthe spring 6, the valve 5 is forced away from its seat,allowing liquid refrigerant to flow into coil I. The charge contained in'the thermal device is superheated gas with the pressure automatically thermal chamber b9.

limited to the particular maximum operating pressure in that individual system, or only slightly less. Thus, since the suction pressure drops rapidly after the compressor starts until valve 5 opens, and since a high operating suction pressure usually causes an overloaded condition in the compressor and motor, the automatic limited charge acts to reduce the time period of such over oaded condition to "negligible proportions.

If, due ito unusual conditions, the casing 3, pipe [0 and coupling 4, are placed in the open ,air outside the refrigerated space, as has been "done in prior systems a high pressure charge in itheithermal -devicemay force valve 5 open during the idle period, causing a flooded condition in the lowpressure portion of the system, with probable damaging results. The low automatic limited charge will not i'force valve 5 to open no matter how .high the ambient temperature, because superheated gas expands but very little with considerable increase in temperature.

it, as with certain high temperature evaporators, a warmer-Hence charge higher than'the maximum operating pressure is required, this higher charge is =easiiy effected manually, by turning the electrical "switch off and raising the as pressure :in-cofl 'and"'c',oupling 4 to a point slightly above the pressure required in the then mal device, during "which process gas forced into the same at the proper pressure, and "the 'system is ready for'operation.

With the compressor inopera'tion and valve "'5 in open position, refrigerating performance is somewhat improved over that "of the "conventional expansion valve with externally zclarnped bulb. 'Evaporating liquid refrigerant flows through coil l, and gas slightly superheatedab'ove the temperature ofth'e evaporating liquid passes through coupling '6, in intimate contact with member 15 and the gas in thermal chamber :39, the temperatureof the latter "being substantially the same as that of the gas "flowing through coupling l. Thermal chamber 39 hassufiicient space to contain, when condensed, all 'of the'gas in the thermal device, including pipefllr'andpressure space 2 9, and according' ly'the pressure in space 29 and onth-eouter surf-ace of diaphragm 8 is that which corresponds to *the temperature of the mow chilled and semi-saturated "gas in The temperature {of "the latter is higher than that of the liquid in'co'il "1,

there exists -'an excess of pressure on the i'outer surface of diaphragm -B --over that -on "the inner surf ace of same, suc'lrexcess-pressure corresponding elire'ctly to the superheat of the gas in 'coupling l the refrigerant allbeing the "samewith identical pressure-temperature relationship. To obtain *maximum capacity and efiiciency "in any coil, the super-heat at its outlet should be "as low as possible providing valve 5-closes-Whenever, due to liquid surging through intothe "sucticniineafi, such 'superheat approaches, or reaches, zero. Whereas the conventional expansion valve with externally clamped bulb, due to the effect of higher ambient temperature, andslowerxand less accurate -response to temperature changes the adjacent suction line, requires arsuperheat justment averaging about 1'0" theen'closed, intimately contacting and sensitive "thermal chamber "39 permits a-superheat adjustment of about 5 or 6 'R with attendant increase-in coil capacity and'efiiciency.

collar 30 resting on theinner end of this nut.

The spring 22 holds the rim 30 against the nut 28. and the member l5 projects through the nut into the bore of the coupling so as to be in contact with the refrigerant passing therethrough. The foregoing is a compact, replaceable fitting which screws into the boss l3 on the coupling 4' by the external threads on fitting 26. The operation of this device is the same as above described.

In Figure 3, the diaphragm 8' in the boss 9 has a central aperture 8a, and the stem I of the valve 5 has a tapered upper end la that can fill this aperture and obstruct it fully. With this construction the thermal element is charged through the aperture 80. instead of through cou pling 4 or 4'; the springs 22 or 22' are omitted, and the member I5 is firmly attached to, or made a part of, the wall of coupling 4, or if the fitting of Figure 3 is used, the valve I5 is omitted and the nut 28 has no hole therein. Charging of the thermal device takes place the same as heretofore described, gas pressure in coil l exerting pressure on the inner surface of diaphragm 8 which is forced outward, away from the pointed end Ia of the valve stem 1'. The aperture 80. is then open and clear for the passage of gas into pipe l and thermal chamber 39 .or 39. Purging is accomplished by loosening of nut 2| or a vent plug opening into thermal chamber 39 or 39'.

The utility of the device will now be apparent. The construction of the coupling permits any desired or limited charge into the pipe H] and operation and control solely by inside conditions is afforded. The screw 36 in the cap can be employed for venting or purging. The fitting member 26 has a flange or collar 31 which engages tightly the rim of the boss I3.

The superheat in coupling l is controlled by the pressure of the spring 6 on the valve 5, said superheat and spring pressure being increased or decreased by turning adjusting stem ll inward or outward, respectively.

The device requires no external bulb or clamp and need not be precharged. When it is connected in place the device is self-charging and all that is necessary when all the connections have been made and the system itself is charged with refrigerant is to remove the screw 36 so that the line Hi can be vented. The refrigerant in the coil I when it fills the coupling 4 in line 25 lifts the valve l5 and fills the line In with the same refrigerant that is used in the operation of the system. The charge is limited to the pressure in the coupling 4. The device is suitable for all refrigerants and is completely self-enclosed and self-contained making a separate thermal unit. It can be interchanged or renewed at will and is well adapted for replacing an old feeler bulb that has to be clamped to the return pipe 25.

Having described my invention, what I believe to be new is:

1. A refrigerating system having an evaporator coil, a casing containing an expansion valve at the inlet end of the coil, connection for supplying refrigerant to the coil through the casing and a connection for conducting it from the coil at the outlet end, a coupling at the outlet end of the coil, a heat transferring member in said coupling, means in. said casing for controlling said valve, and an open conduit connecting said coupling and said means, said coupling having.-a..fitting attached thereto, the fittingbeing hollow, and closed by a hollow nut at its inner end, the. member projecting through the nut into the. coupling, and having afiange at its end engaging said nut, said fitting having aspringthereinpressing said member, and a neck on its outer end secured to the conduit.

2. A refrigerating systemhaving an evaporator coil, a casing containing an expansion valve having a stem at the inlet end of the-coil, connection for supplying refrigerant to-the coil through the casing'and conducting it from the coil at the outlet 'end,l and aconnection for a thermal device having an'open pipe united at one end'to the casing and having its opposite end disposed "adjacent the outlet of the coil, and means for controlling the valve in the casing, said device having a movable heat-transferring part and a portcontrolled thereby to put said pipe into communication with said last-named connection to'admit refrigerant in said lastnamed connection to said pipe.

3'. A refrigerating system having an evaporator coil, a casing containing an expansion valve having a stem at the inlet end of the coil, connection for supplying refrigerant to the coil. through the casin and conducting it from the coil at the outlet end, and a connection for a thermal device having an open pipe united at one end to the casing and having its opposite end disposed adjacent of the coil, and means for controlling the valve in the casing, said device having a movable heat-transferring part and a port controlled thereby to put said pipe into communication with said last-named connection to admit refrigerant in said last-named connection to said pipe. said part and said port being adjacent the outlet of the coil.

4. A refrigerating system having an evaporator coil, a casing containing an expansion valve having a stem at the inlet end of the coil, connection for supplying refrigerant to the coil through the casing and conducting it from the coil at the outlet end, and a connection for a thermal device having an open pipe united at one end to the casing and having its opposite end disposed adjacent the outlet of the coil, and means for controlling the valve in the casing, said device having a heat-transferring part and a port controlled thereby to put said pipe into communication with said last-named connection to admit refrigerant in said last-named connection to said pipe, said means being in the casing and having a port therein.

5. A refrigerating system having an evaporator coil, a casing containing an expansion valve at the inlet end of the coil, connection for supplying refrigerant to the coil through the casing and a connection for conducting it from the coil at the outlet end, a heat-transferring member adjacent said last-named connection at the outlet end of the coil, means in said casing for controlling said valve, and an open conduit between said means and said member, the connection containing said member having an aperture in which said member is movably mounted and a cap over said member and united to the conduit so that said member may respond to pressure in said last-named connection to admit refrigerant vapor from said system into said thermal device.

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