US2734346A

US2734346A - dickieson

Info

Publication number: US2734346A
Authority: US
Publication date: 1956-02-14
Anticipated expiration: 1973-02-14

Description

Feb. 14, 1956 E. F. DlcKlEsoN, .1R 2,734,346

r APPARATUS FOR CONTROLLING REFRIGERATING SYSTEMS Filed Feb. 4, 1949 3 Sheets-Sheet l Feb 14, 1956 E. F. DlcKlEsoN, JR 2734,346

APPARATUS FOR CONTROLLING REFRIGERATING SYSTEMS Feb. 14, 1956 E. F. DlcKxEsoN, .1R 2,734,346

APPARATUS FOR CONTROLLING REFRIGERATING SYSTEMS Filed Feb. 4, 1949 3 Sheets-Shee1'l 5 United States Patent APPARATUS FOR CONTROLLING -REFRIGERATING SYSTEMS Edward F. Dickiesoln Jr., Detroit, Mich.; Nathalie L. Dckieson, executrix of said Edward F. Bickieson, Jr., deceased, assignor to Nathalie L. Dckieson v Application February 4, 1949, serial Np. 14,585

7 claims. (ci. 62-4) This invention relates generally to refrigeration and more particularly to a method of and apparatus for the control of a refrigerating system whereby the condensing unit thereof is prevented from becoming overloaded.

An object of this invention is to provide an improved method for operating a refrigerating system. ff Another object of this invention is to provide a new controlling means for controlling the flow of vapor to a-compresson f A` further object of this invention is to provide such a mechanism with means responsive to the suction pressure of the compressor. Y g

A further object of this invention is to provide such a means which is responsive to discharge pressure of the compressor.

A'further object of this invention is to provide a novel control system having the aforesaid characteristics and the control of which is additionally-modied inaccordance with conditions contained with the space to be re'- frigerated. t t

Other objects will be apparent from the specification, the claims appended thereto and the drawings in which drawings Figure 1 is a diagrammatic view of a refrigerating system embodying the invention;

Fig. 2 is a view in partial central vertical section of a control element embodying the invention which may be utilized in the system of Fig. l, the device being connected between the outlet of the evaporator and the inlet of the compressor;

Fig.' 3 is a view in central vertical section of a fied form of the control element shown in Fig. 2;

Fig. 4 is a schematic view of a refrigerating system embodying a modified form of the invention; g

Fig. 5 is a view similar to Fig. 3 showingthe manner in which the apparatusv of Fig. 3 may be modified to accommodate itself for use in the refrigerating system shown in Fig. 4;

Fig. 6 is a view in central vertical section of a control mechanism used in the system of Fig. 4 the device being connected between the receiver and the compressor inlet and in open communication with the evaporator;

Fig. 7 is a diagrammatic view of a still further modied form of refrigerating systems embodying the invention; and

Fig. 8 is a View in central vertical section of a control element for actuating the throttle of a governor-controlled gasoline engine in the system of Fig. 7, the control element of this figure being employed to vary the setting ofthe governor over al definite range of engine speeds, the control device of Fig. 6 being used to further vary the compressor capacity when necessary in accordance with the demands of the space refrigerated. A

Referring to the drawings by characters of reference, 1 indicates generally a compressor having its discharge outlet connected by means of a conduit 2 to a condenser 3 wherein the gaseous` refrigerant pumped by the compressor 1 is condensedto a liquid in the usual manner.

modi- 2,734,346 Patented Feb. 14, 1956 A receiver tank 4 receives the condensed liquid from the condenser 3. Liquid refrigerant ows from the tank 4 through a conduit 6 under control of a thermostatic expansion valve 8 to an evaporator 10 located within a space 12 which is to be cooled. The evaporator 10 is connected by means of a suitable conduit 14 `to the inlet 16, Fig. 2, of an overload controlling mechanism genrally designated 18. The outlet 20, Fig. 2, of the mechanism `18 is `directly connected to the inlet port of the compressor 1. f A suitable source of rotative energy such as the electric lmotor 22 may be connected as by means ofa belt 24 for driving the compressorl.

lThe motor 22 is controlled in a suitable manner such as a thermostat'generally designatedl 26 and embodying an on-and-otf 4switch (not shown) for making and breaking currentin one or both of the lines L1 and L2. The thermostat 26 embodies a temperature sensitive element y28 which is located within the space 12 to be cooled and operates in the usual manner to close the switch contacts in the thermostat 26 upon increase of temperature in the space 12 above'that desired and to open the contacts in the thermostat 26 when the temperature in the space 12 falls to a predetermined low limit. It will be vapparent `that if desired a control such as that shown in my copending application, Serial No. 750,947 filed May 28, 1947,'now U. S. Patent No.2,626,506, for Control Mechanism, could be used to vary the rate of speed of the motor 22` instead of merely turning it on `and off' whereby the temperature within the refrigerated space might be maintained within predetermined limits. It will be obvious that a gasoline engine or othery source of prime energy could be used to drive the compressor 1 and the operation of the engine be controlled by a suitable temperature responsive element adapted for use with that particular source of prime energy. Such an element and system is shown in my above-mentioned U. S. Patent No. 2,626,506, and also in my U. S. Patent No. 2,626,507 for Method and Apparatus for Controlling Refrigerating Systemsl The energy required to drive a compressor 1 will be a function of the weight of the uid being transferred by the compressor'per unit of time and also proportional to the difference in pressure between which the uid is transferred. As is well known in the refrigeration art, when the `temperature of the evaporator 10 is higher than normal, the refrigerant pressure therein increases and more power is required to drive the compressor. lf the driving mechanism,.such as the motor 22, were selected so that there would be suicient power to drive the cornpressor 1 at all pressure conditions imposed thereon then when the vcompressor 1 is operating with normal pressures in the evaporator 10 andthe condenser 2, the motor would be partially loaded and would not operate as efliciently as a more nearly fully loaded motor. Also the cost of the larger size motor would make its use uneconomical. The control 18, placed in the suction line 14 and in communication with the inlet port to the compressor 1, regulates the pressure at the compressor inlet and consequently the weight of fluid being pumped by the compressor to prevent such weight-from becoming excessive and morethan the motor 22 is capable of pumping.

The apparatus 18 comprises generally a housing member 30 having a uid flow passageway 32 leading from the inlet 16 and opening into the outlet 20. In this passage is arranged a valve member 34 which may be of the balance buttery type as shown pivoted upon a shaft l valve 34. That is, when thevalve 34 is in the position as shown, maximum lluid can ow through the passageway 32 while when the valve has been rotated clockwise from the position shown to a substantially closed position, the tlowof .iluid through .thepassageway =16is -substantially reduced if .not entirely stopped. lhe positioning of the valve 34 is vrdetermined by Vtheresultantof the forces exerted by a piston .-38 sensitive lto dischargepressure and by the lipid force exerted on 1.a movableidisk 40 within the pressure chamber 4 2. 'Iheiplessure 1vvithinwtlle chamber 42 is lsubstantially .that -which appearsat -the end of `the passageway 32 adjacent the outlet 20, such vpressure being communicated thereto Ythrough an aperture 43 in the side wall of -the passageway .32 and sogpositioned that it will be ontheend of theipassageway .32adjacent the outlet 20 and separated from theinlet 16 by means of the valve y34 as the valve-moves-toward 'closed position.

The housing 3,0-is provided with -a hollowbossx44 extendingoutwardly ofthe Side wallof thspaSSgeway .32 coaxially of the yaperture `43and serves as .the outer peripheral wall o frvthe :chamber 4 2. The `inner wallsof the chamber -.42 -comprises Vthe peripheral surface of :a bellows member 46. The member 46 fis'sealed atA one :end-to .an annular plate 4 8 Vwhich abuts l.the outerend wall ,of ,the boss 44 to form an .end Wall of Lthechamber 42. ,The member 46 is sealedv at its other-end to the disk 40 within the chamber 42 and` inwardly .of -the common wall: section 49 between vthe passageway 32 and the pressure .chamber 4 2. A Ythrust rod 5 0 ispivotally isecuredatone .end.portion by the pin 52 4to the butterflyvalve 34 and issecured at its other end to the disk40 Yas oy meansfof atscrew 51. One end portion of apiston r..o.d 54 is also pivotally secured by .the pin 2to .the valve 34 and atl its `other end portion is made semi-spherical for reception in amating semi-spherical aperture in the piston 38. The `piston 38 is snugly butslidably positioned within a piston chamber 56 which yis located in la b oss.57 extending-outwardly of the passageway 32, and .is preferably coaxial with the chamber 42 and aperture 43. The portion ofthechamber 56-.outwardly of the piston 38 is s uitably :arranged to :be connected by means of conduit 58 to thedischargeconduit V2 whereby the discharge pressure of thefcompressor 1 acts upon the piston 38 to urge it in arghtward or inward direction (Fig. `2) in proportion to .the discharge pressureof the compressor.

The compressor suction .pressure is transmitted `through the aperture 4 3 into'the chamber l42fand acts `upon Lthe end member 40 of the :bellows .46 ;in .a .direction .to col.- lapse the bellows 0r move :the Wall 40 'toward'.the right. In -this manner an Iincrease iineither or both the .suction and discharge pressure of 4the compressor 1"will exert a force vtending to close the valve 34 .to reduce .the working load on fthe compressor. A spring-^62 .is located concentrically within the bellowsmember :46 .and is `arranged with its oppositeends abutting lthe disk A40 :and a transverse wall 64Irespectively. The .forcezexertedby the spring will-.determine :the pressures necessary 'in lthe chambers 5.6 and 42 .for positioning the valve :34 in its various controlling positions. The #transverse wall vor plate member -64 forms the fixed wall of :the .expansiblecontractable chamber 6 5 formed 'within the bellowsmember 46 and is provided with afluid flow restrictingorifice 66 extending therethrough. Ahollow cap :68 isrsecured to the -outersurface of theiplate member 64f-with its. hollow :interior or chamber 69, facing the :memberl 64'. AI-he cap 68, plate members 64 and 48 are suitably held tightly together and to :the end -wall of ,the boss -44lin .fluidtight engagement by lmeans of cap screwsor other means (not shown).

The chamber 65 is completely filled and the chamber 69 partially filled fwith a uid such as oil. The .oil is;introducedl into. the chambersfGS and 6 9 vthrough an .intemally-threaded aperturef/'U in the cap :68 =which,after .introduction of the oil, is closed as lby means lof yfa'p1ug""/'2, such lintroduction preferably ibeing made Awith the axis of the chamber 165Y extending in a vertical direction lwith the aperture 70 uppermost. The plug 72 has a venting aperture 72a to permit the iluid level therein to vary while still being maintained :at atmospheric pressure. The member 64 is provided with a passageway 73 for venting of the chamber 65 during the introduction of the oil after which it is closed by a plug 74. As the movable wall or disk 40 moves back and forth, the volume of the chamber 65 varies 'and the necessary oil `lows'through the orice 66, the restriction to How Athrough the orifice 66 acting to damp the -movement vof the movable wall 40 and the butterfly valve member 34 softhattheposition of the valve member 34 will be substantially proportionate :to the average discharge .and suction pressure .rather than to in stantaneous or transient pressures which might appear for various reasons and .also prevents a hunting action of the valve.

The position of the valve member 34, as shown in Fig. 2, is .that in lwhich :the compressor is .operating at or below its maximum rated loading. Let us now assume that for some reasons, such as the placing .of an article yto'be refrigerated in thespace 12 the pressure withintheevaporator 10.increases. This increase of pressure will normally increase the pressure at the inlet of the compressor 'land a greater weight'of refrigerant gas will bepumped per unit of time by Ythe .compressor 1. This increase in Weight of the gas being pumped by the compressor 1 .increases the power required to drive the compressor and also tends to increase the discharge pressure .due to the fact that a greater differential in temperature must be maintainedzbetweengthecondenser 3 and vthemedium to whichthe added heat is dissipated. `This increase in suction pressure passes through the aperture 43 and reacts upon the outer .face of themovable Iwall -40 tending `to move the .wall to :the-right. Upon :the occurrence .of a predetermined combined value O fdischarge .and suction pressures which may be 1an increase in either .or both, the controlling mechanism 18 will start to throttle the ow of suction vapor to .thecornpresser duetomovement of the .valvei34 towardclosedposition. This increase :in one .or both the discharge and suction pressures acts on the piston 56 and the wall .40 tondiugfto urge them toward right to rotate the .valvel34 in a clockwise direction restricting the owof refrigerant vapor frorn'the evaporator 10 tothe compressor ,1. lThe relative ,pressure :areas of the piston 56 and wall 40 .are chosen .itoprolducen effect `corresponding to the relative changein :power .characteristics of the compressor with change in suction and discharge pressure. The spring 6 2 `is chosen to calibrate 'the 4mechanism 1-8 .to .the absolute magnitude of pressure so that the .throttling :effect of the valvev 3 4 vto control the .quantity of suction'gas admitted to the compressor will not permit the compressor to receive `agreater -weight .of refrigerant vapor than that for :which the vmotor 22 is designed. As the evaporator pressurefalls the .opposite effect will be .produced on the apparatus 18 to reduce any restrictive .effect of thewalve 34.

In Fig. 3 there is .shown a -modiied form of .control apparatus 18a 'which .acts to perform Va similar function as does the apparatus =18 but is koperated :by servomotor 9.0 responsive to fthe intake -and exhaust pressures ofthe compressor -1. In this form, the intake or suction pressure is applied directly to the chamber 118 while the discharge or exhaust apressure of -the compressor 1 .is appliedftotheundersidc. of the'valve .13.4 Whichslides within tl 1,e .bushi-ng 92. Theupperportionpof the value 1'34 .isof larger diameter thanthe port 136 to provide an annular pressure -sensitivearea -against which the .discharge i pressur e actst o .exert a force on vthe Awall 130 proportional to the discharge pressure. The diameter .of the port 136 may remain .constant while the outer Adiameter of thevalve1-34-and. inner diameter of the bushing 92 may be'-vari ed'to :providelthe correct area of annula-r pressure sensitive 'area relative ltothe area of wall 130 for'opcration off'the `valve -1'14 substantially as described in connection'with-the operation of valve 34.

.5 The apparatus shown ineFig. 3 comprises a pair of

hollow housing members

100 and 102. The housing member 100 is provided with an inlet opening 104 adaptedgto be secured to thesuction conduit 14 or equivalent ofa refrigerating system whereby the suction gases from the evaporator may be introduced to the interior of the hollow housing member 100. The housing member 100 also has an outlet passageway 106 leading from the hollow interior thereof outwardly. of the housing member and is adapted for connection to the intake port of thecompressor 1. The housing member 100 is also provided. with a piston chamber 108 in which a piston 110 is positioned for movement. The piston 110 has a piston rod 11,2 at one end of which is carried a valve member 114 which is coactable with a valve seat 116 through which the suction vapors pass from the inlet 1.04 to the hollow interior of the housing member 100.

` The interior of the housing member 102 is open to the hollow interior of the member 100 through a hollow tubular member 122 which is press-fitted or otherwise suitably sealed as by brazing to the

body members

100 and 102. A bellows member 124 is positioned within the chamber 118 and is secured at one end to an annular' ring 126-which Vis clamped between a cap member 128 and the body member 102. The other or lower end of the bellows member 124 is closed by means of a movable wallor disl; 130 so that a pressure chamber 118 is formed ex'teriorlyV ofthe bellows 124. The interior of the bellows 124isopento atmosphere through bleed passageway 4131 in the cap member 128. A controlling memberV such as needle valve 134 is actuated by the wall 130 and coacts with valve port 136 to control flow of high pressure refrigerant vapor from an inlet 138 to an outlet conduit V140 for providing the necessary energy to actuate the valve 114. Atubular member 141 is carried by the cap member 128 and serves as a stop to limit upward movementv of the end member 130. The usual helical coil spring 142 is arranged interiorly of and concentric with the bellows 124 and seats at one end against the cover member 128 and its other end against the inner surface of the movable wall 130. It will now be apparentv that the valve 134 will be actuated by change in pressure within the housing 100 to control the flow of actuating fluid to actuate the valve 114.

The piston rod 112 associated with the valve 114 is provided with an internal bore 146 which fits over a guide member 148 carried by the housing member 100 whereby the piston rod'1l2 and valve 114 will be guided for vertical movement. In order that there may be no fluid pocket within the bore 146 to interfere with free movement of the valve 114 in accordance with change in pressure across the piston 110, the piston rod 112 is provided with a venting passageway 150 opening outwardly through the piston rod 112 into the hollow interior of the housing 100. The piston 110 is provided with a controlled or restricted fluid ow port 152 for a purpose which will be made clear presently.

Y It is believed that it will be obvious from the discussion of the operation of theapparatus of Fig. 2 that as the suction pressure of the compressor increases such increase in pressure will be transmitted through the passageway 120 formed by the hollow interior of the member ,122 into the 'chamber 118. Such increase in pressure causes the movable wall 130 to move upwardly thereby moving the needle valve 134 upwardly. Likewise an increase in discharge pressure causes the valve 134 to exert an increased upward force on the wall 130 for moving the wall'upwardly. Such upward movement of the valve 134 permits an increase in fluid flow from the high pressure fluid source through the conduit 140 to the underside of the piston 110. Such flow of iiuid through the conduit 140 will increase the pressure in the chamber 154 proportionately to the amount of opening of the valve port `136. Y Such increase in pressure in the chamber 154 causes the piston 110 to move upwardly thereby moving the valve member 114 closer to the valve seat 116 for restricting iiow of tiuid from the evaporator 8 to the com'- pressor 1 so that the suction pressure of the compressor, 1 does not rise beyond the desired value. Conversely, as the suction pressure and/or discharge pressure decreases, the pressure in the chamber 118, external of the bellows 124, decreases permitting the spring 144 to move the wall downwardly thereby moving the needle valve 134 closer to its seat 136 and lowering the flow of uid to the conduit to the chamber 154 thereby lowering the pressure in the chamber 154 permitting the valve member`114 to move downwardly away from the valve seat 116 for decreasing the restriction to uidv ow through the casing 100. The flow capacity of the passageway 152 is suiciently small with respect to that of the port 136 so that a pressure diiferential of varying magnitude across the piston 110 will be established by the varying position of the valve 134.

The refrigerating apparatus of Fig. 4 is similar to that of Fig. l in that it comprises a compressor 1, a condenser 3, a receiver 4, a liquid line 6, an expansion valve 8, an evaporater 10 located in the space 12 which is to be refrigerated, a suction line or conduit 14 and a discharge conduit 2. In this form of the invention the motor 22 or other source of prime mover is'continually energized whereby the compressor is operated continually. The pumping capacity of the compressor however is varied under the actuation of the control mechanism 200 (shown in Figs. 4 and 6) and takes the place of the on-otf thermostat 26 used in the system of Fig. l. The mechanism 200 asY used in Fig. 4 is connected to supply controlled amounts of high pressure refrigerant vapor from the re,- ceiver 4 through the conduit 22,2 to the fluid chamber 154 of the control mechanism 18a whereby the position of the valve member 114 relative tov its seat 116 may be controlled as a function of the' pressure in the evaporator 10 to maintain a desired temperature in the. space 12. AIn this regard it will be noted that the control of the mechanism 18a by the mechanism 200 will not interfere with the before described operation of the mechanism 18a by the control 90 to prevent undue overloading of the driving motor 22 since the overload controlling function occurs at high evaporator pressures and the temperature controlling function occurs at low evaporator pressures in which this motor 22 has ample power to drive the compressor 1. ln the system of Fig. 4, there is provided a valve 114 actuated by two controlling devices to perform an evaporator controlling'function at low evaporator temperatures and pressures and a compressor controlling function at high compressor power requirements to limit the compressor loading so that the power required'thereby does not exceed the power which may safely be delivered by the motor 22.

The mechanism 200 is shown and claimed in my copending application Serial No. 74,586 iled February 4, 1949, now U. S. Patent 2,626,507. Essentially the ap.- paratus 200 comprises a pressure sensitivechamber 202 communicatively connected by passageway 204 and conduit 206 to the evaporator 10 whereby the pressure in the chamber 202 is proportional to that in the evaporator. The position of the movable wall 208 will be a function of the pressure within the evaporator l0. The wall 208 moves a controlling valve element 210 whereby tluid ilow past the valve seat 212 is controlled as a fuction of evaporator pressure. High pressure iluid from the receiver 4 is conveyed by means of conduit 214 to the inlet 216 of the apparatus 200 which is in open communication with one side of the valve seat 212. Fluid passing through the seat 212 ows into the chamber 218 which has an outlet 220 communicatively connected by means of conduit 222, Fig. 5, to an inlet 224 opening into the chamber 154 and which was shown plugged in Fig. 3. When plugged, the mechanism 18a is adapted for use as above described in the system of Fig. l. When the inlet 224 is connected with conduit 222 as shown in Fig. 5, the

mechanism is suitedfor use in the system 'oiFig 4. A contr1`knob'226of the apparatus 200 is rotated' so `that 'the spring 228 will oppose upward movement ofthe 'movable wall'208 Asu'iciently so that the valve member '21'0 wfill Zbe positioned relative Yto the valve jport 212 at the iesired evaporator pressures to regulate the flow of the high Lpressure uid to the chamber1'54 to cause the' valve mcmber`ll4,'Fig. 3, to be positioned relative to its seat 116 torestrict'ilow of 'uid from the evaporatorlt) to thecompressor l. 'This *position is such asto permit just'suf- Vticientfuid owfro'mthe evaporator 10 to the compressor 1 to maintain the ldesiredpressure in the evaporator'10 irrespective of thefact that the compressor lhasa tendency'to lower this pressure below the desired limit.

7' The control 20'0 may be.used .with or without the `overload `servomotor90 vvshown in ',Fig. 3. lf used without the -overload 'servomotor 90, the yconduit 149 may be removed andthe opening `into .which the conduit 140 was .Connected maybe closed as by a plug. Under these conditions an increase in evaporator pressure reduces uid how Athrough -theiport 212 thereby reducing the pressure I.differential across the piston 11,0 permitting the valve 114 to move further awayfrom its seat 116. If both the servomotor VS90 and control 290 are used in combination to supply juid to the chamber 1'54, the valve member .114, during periods when the evaporator pressure is such as to cause overloading of the motor 22, is positioned relative to its vseat'116 -to restrict the inlet pressure of the compressor 11o a value such as to prevent `undesired overloading of the motor 22 as described it being realized at'thi's time that the valve 210 will prevent uid flow through the port 212 and the conduit 222 is effectively plugged and the valve member 114 is controlled by the valve 113.6. As the evaporator and/ or condensing ,pressures are reduced into the `rangewhi'ch will not cause undesired overloading of the motor 22, the valve 134 will plug the port 136 and conduit 140 is in effect plugged calling for 'full open position ofthe valve member 114. Asthe evaporator pressure tends to be lowered below the desired pressure, the valve member 114 againthrottles fluid'ow and is regulated by the control 200. The reduction in pressure in the evaporator is transmitted to the chamber`202 causing the valve`210 to open the port 2'12 for'uidiowto the chamber 154for movementof the piston 110 and valve/114 upwardly whereby uid ow throughthe port 116 is reduced to the vapor withdrawing effect of the compressor 1 on the evaporator 10.

"If desired unidirectional fluidow valves 230 may be placed in either-or both of the

conduits

140 and 222 to insure that there is no reverse uid flow therethrough. It will thus be evident that in the form of the invention disclosed in Figs. 4, '5 and 6, the refrigerating system acts to prevent undesired overloading of the Vmotor 22 and further permitscontinued operation thereof without causing an undesiredlow temperature of the evaporator I;and.space 12.

1n .the modification shown in Figs. 7 and 8, there is shown a gasoline engine 22a having a4 governor 250 for controlling the speed of operation thereof between predetermined limitsand which also includes `the regulator 12001'for controlling the refrigeration eiect of the vcompressor 1 and the load limiting features as shown .in .Figs 1 and A. Thisgovernor is controlled by atpiston cylinder combination'ZSZ shown connectedin the system in Fig. 7 and in detail'in Fig. 8 and more completely disclosed in my said copending application Serial No. 74,586. In this form the control mechanism 18a is actuated at high compressor,powerrequirements to control .the valve member'1`14 relative' to .the seat 116 to prevent the 4power requirements of the compressor'from exceeding the power which-*may safely be deliveredby the engine 22a in a mannersmiiar to that described above under control o'f the servornotor'-90. The vmechanism 200 upon a reduction in the-temperature 1of space 12 as reflectedby a reduction in `evaporator temperature to 'first actuate the governor controlling combination or device 252 Ato reduce 'the speed of 'the engine 22a tolower thel pumping capacity of 'the compressor '1 to prevent an undesired reduction in temperature ofthe space '12. Since engines, and especially air cooled engines, do not perform well below a-mnirnum speed it is not desirable to continueto reduce the speed below this minimum speed. In many instances this minimum -speed results in drivingthe compressor at a speed in which it reduces the temperature of the evaporator 10 lsufficiently to reduce the temperature of the space 12 below that desired. Under these conditions the mechanism '200 often reduces'the engine speed to the minimum speed then actuates the mechanism 18a to move the valve member 114 toward the valve seat 116 to throt- 'tle the iiow of suction vapor from the evaporator tothe compressor. The system of Fig. 7 therefore provides a continuously operating refrigerating system whichis prevented from overloading the engine by throttling of the suction vapor and prevented from reducting the'temperature of the space 12 below .a desire'dtemperature by reducing the engine speed to reduce the capacity of thc compressor and by throttling the suction vapor to'the compressor to further reduce the capacity of the compressor. The combination 252 has a fluid inlet 1254 which is connected as by means of branch conduit.256 to the conduit 222 whereby it is under control of the apparatus 200 shown in Fig. 6. The apparatus 200 also acts to control the valve 114as described in connection with the system of Fig. 4. The inlet 254 opens into a chamber 258 closed at its upper end by a piston 260`having a restricted Vfluidow passageway 262 therethrough and opening into a chamber 264 above the piston 260. The chamber 264 has an outlet 266 connected by means of conduit 268 directly to the inlet of the compressor 1 whereby the chamber 264 is maintained at all times substantially -at vthe inlet pressure to the compressor 1. A pistonrod 270 Vof the piston 260 extends .outwardly of. the combination 252 for connection with the governor 250. The chamber 254 is suitably sealed against loss of Huid to or reception of fluid vfrom the ambient air 'by means of bellows 272.

`It is believed that it will be apparent from the foregoing that as the valve 210 is opened to permit a greater uid ow through the port 212, as described above, uid will pass through

conduits

222 and 256 to the chamber'258 causing Aa pressure increase in the chamber'258 and a movement of the piston 260 and rod 270 downwardly to move 4the throttle toward closed position to decrease the compressor speed. Movement of the piston 260 downwardly maybe limited by a cylindrical stop 274 or 4the throttle movement under control of the piston 260 toward closedrposition may be limited by any other suitable means whereby the minimum operating speed of the engine 22a maybe predetermined. By such a combination, the engine may be operated continuously within a speed range which permits of suicient cooling by the fan 276 with which engines of the type customarily used for these applications are equipped, prevents the evaporator 10 and space 12 frombeing cooled below the desired temperatures, and to utilize the savings in fuel which are present -with reduced speedioperation.

What is claimed and is desired to be secured by United StatesiLetters 'Patent is as follows:

1. In a refrigerating system, a compressor having van inlet and an outlet, an evaporator connected to receive refrigerant from said compressor and having anoutlet, a suction vapor passageway connecting said evaporator outlet to said compressor inlet, a valve in said suction passageway fortcontrolling fluid flow therethrough and a pair vof valve actuators operatively inter-connected to-,said valve to actuate said valve toward a closedyposition as a result ofthe interaction ofthe etects of said actuators,-a first of said actuators vbeingresponsive to anoperating con-v dition of said evaporator to urge said valve toward av closed position in response to a rst magnitude of said evaporator condition, a second of said pair of actuators being responsive to an operating condition of said compressor to urge said valve toward a closed position in response to a first magnitude of said compressor condition, 4a means for driving said compressor at aV reduced speed, and means operatively connecting said first actuator to said driving means rendering said first actuator effective to control saidV driving means to reduce the speed at which said compressor is driven in response to a second magnitude of said evaporator condition. Y i,

`2. In a refrigerating system, a compressor having an inlet andan outlet, an evaporator connected to receive Vrefrigerantfrom said compressor and having an outlet, a suction vapor-.passageway connecting said evaporator outlet to said compressor inlet, a valve in said suction passageway for controlling fluid flow therethrough and a pair of valve actuators operatively inter-connected to said valve to actuate said valve toward a closed position as a result of the interaction of the effects of said actuators, a first ot said actuators being responsive to an operating condition of said evaporator to urge said valve toward a closed position in response to a rst magnitude of said evaporator condition, a second of said pair of actuators being responsive to an operating condition of said compressor-to urge said valve toward a closed position in response to a first magnitude of said compressor condition, means having a variable power output for driving said compressor, and means operatively connecting one of said actuators to said variable power means rendering said one actuator effective to control said variable power means in response to a second magnitude of the condition to which it is responsive. 3. In a refrigeration system, a compressor, an evaporator, fluid tlow means interconnecting said compressor and said evaporator for providing a regulated tlow of tluid from said compressor to said evaporator, a fluid ilow means interconnecting said compressor and said evaporator for providing a uid llow path from said evaporator to said compressor, means including a flow-restricting device in said last-named fluid flow means, a fluid-powered operating means for said device, and a speed control means for regulating the rate at which said compressor operates, a pair of actuators for supplying actuating uid to said fluid-powdered operating means and said speed control,

means rendering the operation of a rst of said actuators responsive to an increase in the work done by said compressor causing it to supply operating fluid to said uidpowered operating means to cause said now-restricting device to reduce the rate of removal of fluid from said evaporator, means rendering a second of said actuators responsive to a decrease in pressure in said evaporator causing said actuator to supply iluid to said speed control means causing the latter to reduce the speed of said compressor and to said huid-powered operating means to cause said flow-restricting device to reduce the ilow of fluid from said evaporator to said compressor, and means rendering said speed control means inefective to reduce the speed of said compressor below a predetermined minimum.

4. In a refrigerating system, a compressor having an inlet and an outlet, an evaporator having an inlet and an outlet, a first fluid flow passageway interconnecting said compressor outlet and said evaporator inlet and providing a regulated flow of fluid from said compressor to said evaporator, a second fluid ow passageway interconnecting said compressor inlet and said evaporator outlet for providing a fluid ilow path from said evaporator to said compressor, a third flow uid passageway communicatively connecting said compressor outlet and inlet in by-pass relation to said evaporator and including means restricting iluid flow therethrough, a first flow controlling element in said third passageway intermediate said third passageway restricting means and said compressor outlet and controlling fluid flow therethrough, a second low controlling element controlling fluid flow through said second passageway, a pressure sensitive element connected to respond to the pressure in said third passageway intermediate its said restricting meansand` said first ow controlling element and, having a pressure responsive .portion opera- Vtively connected to said second ilow element for actuation thereof, a'par of pressure sensitive elements operatively connected for actuation of said first ow controllingv element and operable upon increase in pressure -to actuate said first flowelement vto open position, one of said actuators being responsive to the pressure of the fluid in said compressor outlet, and the other of said actuators being responsive to the pressure of the fluid inlsaid compressor inlet.

S. In a refrigerating system, a compressor having an'inlet and an' outlet, an evaporator having an inlet and an outlet, a `firstiluid flow passageway interconnecting said com,- pres'sor outlet and Vsaid evaporator inlet and providing a regulated flow of fluid from said compressor to said evaporator, a second tluid flow passageway interconnecting said compressor inlet and said evaporator outlet for providing a fluid flow path from said evaporator to said compressor, a third fluid flow passageway communicatively connecting said compressor outlet and inlet in by-pass relation to said evaporator and including means restricting uid ow therethrough, a first flow controlling element in said third passageway intermediate said third passageway restricting means and said compressor outlet and controlling fluid How therethrough, a second flow controlling element in said passageway in lby-pass relation to said first element and controlling fiuid flow through said third passageway, a pressure sensitive element connected to respond to the pressure in said third passageway intermediate its said restricting means and said flow controlling elements and having a pressure responsive portion, means regulating the rate at which said compressor is operable to remove refrigerant from said evaporator and operatively connected to said pressure responsive portion for actuation thereby, a pair of sensitive actuating elements operatively connected to said ilow controlling elements for control thereof, means rendering one of said actuators responsive to an operating condition of said compressor, and means rendering the other of said actuators responsive to an operating condition of said evaporator.

6. In a refrigerating system, a compressor, an evaporator, a liquid refrigerant passageway including a liquid flow controlling means interconnecting said compressor with said evaporator for supplying a regulated flow of liquid refrigerant to said evaporator, a suction refrigerant passageway including a suction iluid flow regulator interconnecting said evaporator with said compressor for supplying a regulated ilow of suction refrigerant to said compressor, a fluid-powered operating means for said suction fluid flow regulator, a trst actuating device responsive to a minimum operating condition of said evaporator and having a controlling element operatively connected to said fluid-powered operating means to supply operating iluid to the latter causing it to operate said suction tlow regulator to reduce the flow of refrigerant to said compressor, a second actuating device responsive to maximum operating conditions of said compressor and having a single controlling element adapted to supply operating fluid to said fluid-powered operating means to cause the latter to reduce the rate of ow of suction refrigerant to said compressor, said last-named single controlling element having two pressure sensitive elements each having a pressure responsive portion, fluid flow means operatively connecting said last-named single control element with said fluid-powered operating means, pressure conveying means connecting one of said pressure sensitive elements to respond to the intake pressure of said compressor, and pressure conveying means connecting the other of said pressure sensitive elements to respond to the outlet pressure of said compressor.

7. In a refrigerating system, a compressor, an evaporator, a liquid refrigerant passageway interconnecting said compressor and said evaporator for providing a regulated flow of liquid refrigerant from said compressor to affamati saidevaporator, 'a'suction 'conduit 'interconnecting said 'coinpres'sor and saidevaporator'for providingV afinid'flow path *from sa'id evaporator to 'saidconipressoig a valve regulating' the flow of suction refrigerant through said suction 'conduit to'regulate'the rate 'at which suction krefrigerant' :is 'removed "from said 'evaporator' by said .compressor-independently of `the -Vrate at lwh'i'c'h liquid 4refrigetant 'is' supplied to said evaporator 'by said liquid flow regulating -means, atrst'actuator operatively connected Ato control said valve,'means'rendering-said first actuator responsive to an increase in the work done `by said Compressorgtomove 4said-valveV toward closedrpositiOn to reduce 'the' suction refrigerantadmitted to said compressor, means controlling thesp'eed at which saidf compressor 'is driven, a lscond'actuator responsive to an operating condition ofsaid'evaporator, fand r'neans'vrepnderingsaid second actuatojr 'responsive to a decrease-in the magnitude of said evaporator condition'to actuate said compressor speed controlling means to reduce' the speed at which said cornpressor'isdriven.

References 'cited in 'thefueiof' this ypatent Jones Nov.`- 14,' l1933 Thomas "July'24, '1934 Smith Nom-24, T1936 McCormack MayL1'1,`-1937 Euwer Sept. 30;19'41 Homes Dec. 15,11942 Henny "June'l, '-11943 Winkler Ylune 27, 1944 Newton lauf-I6, 1945 'Atchison 'Nov.-`23,11948 I Zearfoss :Sept 20, "1949 Lathrop I-Feb.`= 14, 1950 Lange lun'e, T1950 Schulze et val. Sept."2'6,"1950 Jones -`Jan. 8,' L1952