US2283386A - Air conditioning system - Google Patents

Description

May 19, 1942.

A. B. NEWTON AIR CONDITIONING SYSTEM Filed Jan- 24', 1940 Fig, 2

v nventor Alwin.. Newom MQW/X46?" Patented May 19, 1942,.

UNITED STATES PATENT OFFICE y AIR CONDITIONING SYSTEM Alwin B. Newton, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company,

This invention relates in general to air condinoid valve', the solenoid valves being sequen-l tially controlled in accordance with the cooling load for thereby varying the number of coils in operation in accordance with the cooling load. i

This type of arrangement while being very ilexible and eicient has thedisadvantage of being relatively expensive, due to its requiring a separate expansion valve for each coil.

It vis an object of this invention to provide a` system of this general type which is not only both elective and exible but which also does not re- `v quire a separate expansion valve for each coil. This result is achieved by employinga single largeexpansion valve for the entire group of coils, and by providing a distributor which equally distributes the refrigerant from the expansion valve' to the coils, the cut-on? valves being located in the connections Vbetween the distributor and -coils. A I "1.

Other objects will appear, from the following description and the appended claims.

For a full disclosure of this invention reference is made to the following detailed description and A to the accompanying drawing, in which:

Figure 1 is a diagrammatic illustration of an air conditioning system embodying the features of the invention, and

Figure 2 lis an elevation in section showing the expansionvalveand' distributor arrangement for the direct expansion coils.

Referringto Figure 1, reference character l indicates an air conditioning chamber having a fresh air inlet 2,- and a return air inlet 3 which communicates with a space to be conditioned 4. The discharge end of the chamber I is connected to a ian 5 which acts to draw air through the chamber ,land discharge it through suitable duct means into the space 4. Located within the chamber I is a heat exchange device generally vvindicated as 6, this heat exchange device being adapted-to operate as an evaporator for cooling the`space. 'I'l'ie heat exchange device 6 preferably is formed of a plurality of separate cooling coils or refrigerant passes 1, B, 9, and III. The

right-hand ends of these coils are connected to a suitable header II while the left-hand ends l of these coils are.co nnected to a combined ex- Minneapolis, Minn., a corporation of Delaware Application January 24, 1940, Serial No. 315,365

pansion valve and distributor: device indicated asv I2.

Referring now to Figure 2, this figure indicates the construction of the combined expansion valve .5 and distributor device I2. Referringto the expansion valve portion of this device, this valve may be offthe same type shown in my co-pending application Serial No.v 192,818, led February 26, 1938. `'I'his expansion valve may comprise a diaphragm casing I3 which houses a diaphragm structure formed of diaphragms I4 and I5 and a connecting member I6. The diaphragm or bellows I4 is sealed Ato lthe lower surfaceof the diaphragm casing I3 and the lower `-end thereof is l5 closed by means of a cup member I'I. The bellows I5 is similarly sealed to the upper end of casing. I3, and its openl end is closed by means of a cup member I8. Both the bellows I4 and the bellows` I5v are sealed as by soldering to the member I5 so as toprovide a unitary fluid tight device. The cup member I1 isprovided with a tting I9 which is connected by a pipe 20 to a fitting 2| located on the header II. A passage 22 is provided within the fitting I 9 for placing 25 the interior of the bellows I4 into communication with the interior of the header II. The pressure within bellows I4 is therefore equal to the ,preslsure within this header. Also located within the fitting 2 I is a thermostatic bulb 23 which is connected to a capillary tube 24 locatedwithin the pipe 20, this tube 24 being attached to the fitting c I9 in a manner to communicate with a passage 25 in this fitting. This passage 25 is connected by means of a coiled tube 26 located within the bellows I4 to the interior of the bellows I5. The

bulb 23 contains a suitablevolatile ll which preferably is the same as the refrigerant used in the system. The arrangement Just described therefore will cause a pressure to exist within the bellows I5 which is indicative of the temperature in the header II, while the pressure within the bellows I4 is equal to the pressure within said header. v

Connected to the member I6 is a rod 2l which ,extends upwardly through the cup member I8,

this rod being threaded at its upper end as shown and carrying a nut 28 engaging a spring 29 which is 4supported bymeans of a spring retainer 30. A sealing bellows 3| is provided for preventing the escape of vapor from the bellows I5. With the arrangement just-described it will be apparent that upon an increase in pressure within the header II the bellows I4 will expand and the` v bellows I5 Vwill contract, while upon an increase in temperature at bulb 23 the pressure within bellows I will increase thereby causing expansion of this bellowsand contraction of the bellows I4. The bellows I4 and I5 therefore act in opposition and the vertical position assumed by the connecting member I6 is anindication of out 63 which may be of any suitable type.

the degree'j'of superheat of the refrigerant at the fitting 2I.

The member I 6 is provided with a pin 32 which cooperates with a lever arm 33 extending through an opening 34 into the valve chamber 35. This lever is pivoted tothe valve chamber casing at 36 and carries' a valve member 31 cooperating with a valve port 38 located in 'a nipple 39. A spring 48 is provided for urging the lever 33 in a direction tending to maintain the valve xnember 31 against the valve port 38. In operation, liquid refrigerant enters at `4I and passes through port 38 to the distributor ydevice 42. If the amount of superheat of the refrigerant leaving the coils 1, 8, 9, and I8 should increase, the pres.- sure within bellows I5 will increase this causing downward movement of the member I6, and due to engagement of pin 32 with lever 33 the valve to the header II. This compressor is provided with a combination high and low pressure cut- This device includes a switch (not shown) which is opened upon either anexcessive head pressure or a predetermined low suction pressure occurring.

'Ihe solenoid refrigerant valves and the compressor are controlled by means of a step controller generally indicated as 64. This step controller includes an electric proportioning motor 65 which may be ofthe type shown in the Taylor Patent 2,028,110. This motor is provided with an operating shaft 66 and assumes intermediate positions depending upon the combined eiect of a return air thermostat 61, humidity controller 68 and an outside thermostat 69. The control circuit between the thermostat 61, humidity controller 68 and thermostat 69 may be of the .effec tive temperature type disclosed 'in the Haines Patent 2,173,331 dated Sept. 19, 1939, or preferably may be of the type disclosed in my copending application Serial No. 182,817 filed Decemmember 31 will be move'd away from port 38 to increase the supply of liquid refrigerant to the coils. Conversely, upon decrease in the amount of superheat, thel member I6 will move upwardly, thereby permitting valve member 31 to approach port 38 under the action of spring 48. By.ad justing the nut 28 any desired degree of superheat may be maintained.

Referring now to the distributor device 42, this device consists of a member 43 having a chamber 44, this device being secured to -the valve casing in. a manner to cause the chamber 44 to register with the opening in nipple 39. The member 43 is also provided with a pluralityof restricted radial passages 45 which lead from the chamber 44 to openings 46 which are adapted for individual connection with the-coils of the evaporator 6. It will be understood that a restricted passage 45 and connection 46 is provided for each of the coils. It will be noted that the nipple 39 is formed to provide a venturi and that the chamber 44 is in direct alignment with the valve port 38, so that the stream of liquid passing through the valve is discharged into the chamber 44 at high velocity. Thishigh velocity discharge of refrigerant into the chamber 44 causes the refrigerant to become a homogeneous mixture of liquid and gas within this chamber and to pass through the restricted passages' 45 into the coils 1, 8, 9', and I8. Due to this action of refrigerant within the chamber 44, both the gaseous and liquid refrigerant will be divided ber 31, 1937. This arrangement causes the shaft 66 to be rotated to positions corresponding to the effective temperature of 'the air in the space 4 and this effective temperature is in turn varied by outside temperature in order to maintain comfortable conditions in the space.

which actuate mercury switches 14, 15, 16, and 11. These cams are designed and positioned on the shaft 66 so..that when this shaft reaches its clockwise limit of rotation, the mercury switches are all tilted so as to unbridge their electrodes.

As the shaft 66 rotates counter-clockwise due to an increase in effective temperature, that is, due to either an increase in temperature or humidity in the space, the cam 18 will first tilt the mercury switch 14 to closed position. Upon a further increase in effective temperature the shaft 66 will rotate further in the counter-clockwise direction for causing cam 1I to tilt switch 15 to closed position. Switches 16 and 11 are similarly tilted to closed position in sequence upon continued counter-clockwise rotation of mercury switches in inverse order.

Assumingvrst that the effective temperature within the space is such that no cooling is neces- *l sary, the controls for the motor 65 will cause this motor to position its shaft at its clockwise equally between the various coils. This arrangement therefore provides for the passing of the proper amount of liquid refrigerant to each coil and thereby prevents the flooding of one coil and the starving of another.

Interposed in .the connections between the dis.- tributor 42 and the coils 1, 8, 9, and I8 are solenoid valves 5I, 52, 53, and 54. These valves are of the type which open when energized and which close when deenergized. These valves are provided for the purpose of controlling the number of cooling coils which are in operation.

Referring to the remainder of the refrigeratio system this system includes a compressor 56 which is driven by means of an electric motor 51 having a starting box 58. The compressor 56 is connected by a discharge line 59 to a condenser A 68 which is in turn connected by a lliquid line 6I to theinlet of the expansion valve I2. This compressor is also connected by a suction line 62 limit of rotationat which all of the mercury switches are open. perature due to either rise in relative humidity or temperature, the shaft 66 will be.rotated countercloclrwise for tilting mercury switch 14 to closed position. 'I'his will complete a circuit j from the transformerl secondary '88 of transtrol ofthe controller 84.

cury switch 14, wire 88, solenoid valve 5I, wire 89, and wire 81 to secondary 88. 'I'herefore upon ,an initial call for cooling the compressor Iis placed into operation and one evaporator coil is placed into operation. At this time as the load upon the compressor imposed by coil 1 is quitesmall the pressure of the evaporating refrigerant in this coil will be lowand thus this coil Upon rise in effective tem-y lby coil 1 will be mixed with the uncooled air passing over coils 8, il,` and l0, this mixture being completed in the fan so that air at relatively high temperature is discharged into the space 4. This arrangement thus provides for securing a substantial amount of dehumidication without performing, a large amount of cooling and without the necessity of discharging cold air into the conditioned space.

If operation of coil 1 is insuilicient to carry the existing cooling load, the eilective temperature in the space will continue to rise thus causing further rotation of shaft 63 for closing the mercury switch 15. This will energize solenoid valve 52 as follows: transformer secondary 80, wire 82, wire 90, mercury switch 15, wire 9|, solenoid valve 52, wire 89, and wir'e 81 to secondary 80. The placing of coil 8 in operation will increase the effective cooling area thereby providing a larger amount of cooling. Similarly upon continued increase in cooling load the mer- 'cury switch 16 will be closed for energizing solenoid valve 53 which -places coil 9 into operation, and' if still further cooling is required the mercury switch 11 is closed for opening solenoid. valve 54 and placing I0 in operation. Thus at 4such time the entire cooling coil is employed for obtaining maximum cooling.

It should be noted that when only valve 5| is open, the expansion valve will supply just enough refrigerant to maintain the superheat of the refrigerant leaving coil. 1 at the desired value, the supply of refrigerant to coil 1 being varied in accordance with the rate of evaporation in said coil. When valve 52 is opened for placing coil 8 in operation, refrigerant will 4now be supplied to both coils 1 and 8. Due to the additional heat exchange surface, the' superheat chamber, said cooling device comprising a plurality of separate heat exchange conduits adapted to containrefrigerant and in heat exchange relationship with said air stream, said 'conduits having inlets and outlets, a source of liquid refrigerant, a single expansion valve connected to receive refrigerant from said source, a distributor receiving low pressure refrigerant from said expansion v alve, said distributor comprising a of the refrigerant in header I'IV willl increase, p which will cause the expansion valve to open wider for supplying enough refrigerant to maintain both coils 1 and 8 fully effective. In the same manner, the expansion valve-will readjust itself whenrcoils 9 and I0 are] placed in opera- 'ticn so as to always supply the proper amount of refrigerant to the evaporator 6 as determined by the number of coils in operation. As the coils are placed out of operation, the expansion valve Will reduce the total supply of 'refrigerant correi spondingly. Due to the action of the distributor, the refrigerant will be equally divided among the operating evaporator coils irrespective of the number .of coils which are operating.

From the foregoing description it will be apparent that this invention provides for automatically varying the amount lof coil surface placed in operationin accordance with temperature or humidity or both, this control .of coil surface being secured positively by placing coil sections into and out of operation, the arrangement requiring only a single expansion valve for all of the coils even though the number of coilsplaced y into and out of operation is varied.

As Various modifications of the invention Vmay be made without departing from its scope it is desired to be limited only by the appended claims. p

I claim as my invention:

1. In an air conditioning system, in combination, a conditioning chamber through which a stream of air is passed to a conditioned space, a. direct expansion cooling device located in said chamber communicating with said expansion valve and with a plurality of restricted passages, individual connections between the outlets of said restricted passages and said heat exchange conduits whereby each restricted passage meters the supply of refrigerant from the expansion valveto corresponding heatexchange conduit, ,a separate valve in each of said individual connections, operating means for opening and closing the valves in sequence, and means responsive to the humidity in said space for controlling said operating means for opening said valves in sequence upon rise in humidity and for closing the valves in sequence upon fall in humidity;

2. In an air conditioning system, in combination, a conditioning chamber through which a stream of air is passed to a conditioned space, a direct expansion cooling device located in said chamber, said cooling device comprising a plurality of separate heat exchange conduits adapted to contain refrigerant and in heat exchange relationship with said air stream, said conduits` having inlets and outlets, a source of liquid refrigerant, a single expansion valve connected ,to receive refrigerant from `said source,` a distributor receiving low pressure refrigerant from said expansion valve, said distributor comprising a chamber communicating with said expansion valve and with a plurality of restricted passages, individual connections between the outlets of said restricted passages and said heat exchange conduits whereby each-restricted passage meters the supply of refrigerant from the expansion valve to a corresponding heat exchange conduit, a separate valve in each of said individual connec-A ranged to cause complete opening of the valve when the controller is in one position and for causing complete closing of the valve when the controller is in another position, a movable mem- 'ber arranged to cause movement of said c ontrollers between their first and second positions in sequence upon movement of said member through a predetermined operating range, and means responsive to the humidity in said space for graduatingly positioning said movable member in accordance with variations in humidity.-

3. In an air conditioning system, ,in.,combination, a. conditioning chamber through which a stream of air is passed to 'a conditionedv space, a direct expansioncooling device located in said chamber, said cooling device. compriisng a plurality of separate heat exchange conduits adapted'to contain refrigerant and inheat exchange relationship with said air stream, said conduits chamber communicating -with said expansion4 having inlets and outlets, a source of liquid/refrigerant, a single expansion valve connectdto receive refrigerant from said source, a` distributor receiving low pressure refrigerant from said expansion f valve,` said distributor comprising a valve and with a plurality of'rrestricted passages, individual connections between the outlets of said restricted passages and said heat exchange conduits whereby` each restricted passage meters the supply of refrigerant from the expansion valve to a corresponding heat exchange conduit, a separate valve in each'of said individual' con` nections, an electromagnet foreach of saidv valves, a separate switch for eachof said electromagnets for energizing and deener'gizing the same a movablemember for. vactuating the switches in sequence, a reversible electric motor' chamber, said coolingdevice comprising a plurality of separate heat exchange conduits adapted to contain refrigerant and in heat exchange relationship with said air stream, said conduits having inlets and outlets, and being located side by side in said conditioning chamber. whereby the air stream in said chamber ows across said heat exchange devices in parallel relationship, a source of liquid refrigerant, a single expansion valve connected to receive refrigerant from said source, a distributor receiving low pressure refrizerant from said expansion valve, said distributor comprising a chamber communicating with said expansion valve and with a plurality of restricted passages, individual connections between the outlets of said restricted passages and said heat exchange conduits whereby each restricted passage meters the supply of refrigerant from the expansion valve to a corresponding heat exchange conduit, ka separate valve in each of said individual connections, an' electromagnet for each of said valves, a separate` switchl for each of said electromagnets for energizing and deenergizing the same, amovable member for actuating the switches in sequence, a reversible electric motor for positioning said movable member, and means responsive to the cooling load for graduatingly controlling said reversible electric motor'. ALWIN B. NEWTON.

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