US2504435A - System for controlling refrigeration - Google Patents

Description

April 18, 1950 MATTESON 2,504,435

SYSTEM FOR CONTROLLING REFRIGERATION Filed Nov. 24, 1942 '7 Sheets-Sheet l Tempe/afar! Fespons/ie g Swift/7 74 L H'enure Resp nsive Swifcb 7'mperafuns Expo/251k Sw/fC/I 7o* 23 MM 7/ 73 IN v E TO R Harv/a J fl/a/feson BY ATTORN E! April 1950- H. J. MATTESON 2,504,435

SYSTEM FOR CONTROLLING REFRIGERATION Filed Nov. 24, 1942 7 Sheets-Sheet 2 INVENTOR Hero/0 Wei/#6500 BY ATTORNEY April 18, 1950 H. J. MATTESON 2,504,435

SYSTEM FOR CONTROLLING REFRIGERATION Filed Nov. 24, 1942 '7 Sheets-Sheet 3 /'/TI::ENTOR [W MI W L ATTORNEY April 18, 1950 Filed Nov. 24, 1942 H. J. MATTESON '7 Sheets-Sheet 4 [T1 m j m 74 .59 ea 58 2 5G 1 I; f T 72 57 255 5. 'ZSB N- v E NrroR Ham/0 J. fl/a/feson BY ATTORNEY April 18, 1950 H. J. MATTESON 2,504,435

SYSTEM FOR CONTROLLING REFRIGERATION Filed Nov. 24, 1942 '7 Sheets-Sheet 5 /78 u l l ATTORNEY April 18, 1950 H. J. MATTESON SYSTEM FOR CONTROLLING REFRIGERATION Filed Nov. 24, 1942 '7 Sheets-Sheet 6 2/0 2,3 Zoo 5 NVENT'OR fiao/a fife/#6500 BY ATTOR NEY April 18, 1950 H. J. MATTESON 2,504,435

SYSTEM FOR CONTROLLING REFRIGERATION Filed Nov. 24, 1942 '1 Sheets-Sheet v 7mpemfu/r 18,000)??? v 70 Coo/0'1 2 I I P T L m Patented Apr. 18, 1950 SYSTEM FOR CONTROLLING REFRIGERATION Harold J. Matteson, Glendale, CaliL, assignor to General Controls 00., Glendale, Calit, a corporation of California Application November 24, 1942, Serial No. 466,739

15 Claims. (Cl. 62-8) This invention relates to refrigeration, and especially to the use of refrigeration in air conditioning.

Any suitable refrigerating unit may be provided for such purposes; a common form is one which utilizes a volatile refrigerant, e. g. Freon, absorbing heat during the change of state from liquid to gaseous.

The cycle of refrigeration includes passing the liquid refrigerant to an evaporator, where the pressure is such that the liquid vaporizes and absorbs heat. The gaseous refrigerant then passes out of the evaporator and is compressed. After compression, the gas is liquified by aid of a condenser, and the liquid refrigerant may be again passed into the evaporator.

The control of the passage of refrigerant into the evaporator is accomplished by valve means, that may be caused to respond to conditions in the evaporator. For example, it has been proposed to open the valve when a definite degree of superheat is attained by the vapor. This superheat is measured in degrees, and is represented by the difference between the temperature existing in the outlet of the evaporator, and the temperature which the refrigerant, at the pressure existing in the evaporator, would assume in a saturated state.

The evaporator is usually formed of a convoluted conduit, often referred to as an expansion coil. It is desirable to prevent over-flooding of the coil by too rapid supply of refrigerant; and normally this is easily accomplished by controlling the valve in accordance with a specified degree of superheat, as hereinabove mentioned. But under certain abnormal conditions, a control of this character is not suflicient to prevent an excessive flow of refrigerant into the evaporato'r. Such an abnormal condition may exist when the refrigerating unit is first turned on, upon installation, or turned on after a protracted period of inactivity. Under such circumstances, the degree of superheat is abnormally high, and the valve is caused to remain open for an excessive period. It is not until a substantial period of time has elapsed, that the valve closes, since the evaporator is incapable of evaporating the refrigerant at a rate rapid enough to reduce the degree of superheat below the controlling value. The result is a flooded evaporator, with its attendant disadvantages.

.In a prior application, filed in the name of the present applicant on November 27, 1940, under Serial No. 3 fi7,320, which has now matured into Patent No. 2,309,405 grantedJanuary 26, 1943,

abnormally high temperatures encountered in the space to be cooled cause such operation of the valve that the flow of refrigerant is severely restricted until normal conditions are approached. It is one of the objects of this invention to improve in general upon the system described in said prior application.

It is another object of this invention to provide a simple and eiiective system, capable of performing these controlling acts, resulting in a severe restriction in the rate of flow of liquid refrigerant into the evaporator, upon the occurrence of abnormal temperature conditions; and especially by the aid of electric circuits, controlling an electrically operated valve structure.

The vaporized refrigerant passes out of the evaporator and to the inlet of a compressor. Under normal conditions, the pressure of the refrigerant vapor is quite low, since the supply of refrigerant takes place relatively slowly, and

the compressor is capable of fully withdrawing the gaseous or vaporized refrigerant. However, abnormal conditions may arise that would overload the compressor. Thus for instance, in an air conditioning system utilizing multiple units operated by a single compressor, abnormal temporary climatic conditions involving high temperatures may severely overtax the capacity of the system. This may occur once or twice a year; so infrequently in fact that it is uneconomical to provide sufficient capacity for the system to take care of these occurrences.

It is another object of this invention to make it possible to restrict the flow of refrigerant to the evaporator upon the occurrence of abnormally high back pressure in the inlet side of the compressor.

It is still another object of this invention to provide effective and simple apparatus combining the controls for restricting the flow of refrigerant in response to the abnormal conditions hereinabove mentioned.

It is still another object of this invention to provide an electrically operated valve structure capable of efiicient control in a system of this character.

This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of several embodiments of the invention. For this purpose there are shown a few forms in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles oi the invention; but it is to be understood invention;

Fig. 3 is a view, mainly in vertical section, of a valve structure utilized in connection with the invention;

Fig. 4 is a detail sectional view, taken along plane 4-4 of Fig. 3;

Fig. 5 is an enlarged sectional view of a con- -trol device that may be utilized in connection with the invention illustrated in Fig. 1;

Fig. 6 is a fragmentary view, partly in section,

of a control device that may be utilized in connection with the system illustrated in Fig. 2;

Fig. 7 is an enlarged sectional view, similar to Fig. 5, of a modified form of control device that may be utilized in the system;

Fig. 8 is a sectional view taken along plane 8--8 of Fig. 7;

Figs. 9 and 10 are views, mainly in vertical section, of valves that may be incorporated in the system illustrated in Fig.2; and

Fig. 11 is a diagram similar to Fig. 1, of a modified form of the invention.

In the form shown in Fig. 1, a cooling unit I is indicated. This unit, together with the appurtenant controldevices, is shown as located in a compartment 280 that is to be cooled. In this cooling unit there may be provided an expansion coil 2, utilized as an evaporator. The cooling unit I may be one of several such units adapted to be utilized in an air conditioning system or the like, capable of automatically being set into operation by a temperature responsive device.

Into the evaporator 2 may be admitted a liquid refrigerant such as Freon. This liquid refrigerant is admitted through a valve structure 3 which will be described in greater detail hereinafter. The outlet side 4 of the valve structure 3 is connected to the inlet side of the evaporator 2. The inlet side 5 of the valve structure 3 is connected by conduit 6 to the tank 1 in which the refrigerant is stored in liquid form, after condensing by appropriate cooling of the convolutions 8 in the refrigerant conduit 9. This conduit 9 is connected to the discharge end of a compressor III. The intake end of the compressor I0 is connected as -by a conduit II to a control device I2. This control device I2 is connected to the outlet I3 of the evaporator 2.

The liquid refrigerant in entering the evaporator 2, within which low pressures exist, rapidly evaporates and absorbs heat. The resultant vapor is discharged through the outlet I3 and the control device I2 to the inlet side of the compressor Ill. The compressor I0 discharges the compressed gaseous refrigerant to the convolutions 8 where the refrigerant is cooled to liquify it, and the liquid refrigerant is collected in the receptacle 1. Thence the liquid refrigerant as heretofore stated, may be again admitted intermittently by the aid of the valve structure 3, as required by the conditions of operation.

This cyclic operation in general is typical of refrigerator systems utilizing a liquid refrigerant that absorbs heat by evaporation.

The compressor I 0 is shown as driven by an electric motor I4 adapted to be supplied with electrical energy from the mains I5. If desired, an automatically operating pressure responsive switch I6 may be interposed in the motor circuit- This switch is shown as controlling the motor I4 in response to the pressure at the intake side of the compressor III. Such control of the compressor operation is now conventional.

Control device I2 is illustrated most clearly in Fig. 5. It comprises a hollow body I1 that forms a chamber I8 into which the gaseous refrigerant discharging from the outlet I3 may pass. The gaseous refrigerant proceeds through the control device I2 into the conduit II.

In-its progress through the chamber I8, the control device is arranged to control the valve structure 3 in a manner now to be described.

An important factor in the control is that based upon the degree of superheat of the gaseous refrigerant entering the chamber l8. As heretofore explained, the degree of superheat is measured as the difference between the temperature of the refrigerant in chamber I8, and the temperature of the saturated refrigerant, the pressure remaining substantially constant.

In order to control the admission of refrigerant in response to the degree of superheat, a device is illustrated which is similar to that illustrated in an application filed in the name of William A. Ray on September 4, 1942, under Serial No. 457,302, which has now matured into Patent No. 2,355,894 granted August 15, 1944. For example, the body I1 may be provided with a wall I9 which is apertured as illustrated at 20 for the reception of a member 2I. This member 2| is formed as a flexible wall that is movable in response to variations in pressure exerted thereon. It may take the form of a corrugatedmetal bellows. The upper'end of the metal bellows is joined in a fluid tight manner to a flange 215. This flange 215 is shown as attached to the outer side wall I9, as by the aid of an overlying ring 22 and the cap screws 23 threaded into the wall I9.

The ring 22 is also in fluid tight relation with the bellows 2|. Its inner edge is joined to an inner corrugated metal bellows 24. The lower ends of the bellows 2| and 24 are joined by a rigid lower head member 25 and are sealed thereto. In this way a closed annular space 26 is provided, sealed off as indicated by the seal 21. Within the space 25 is a body of vaporizable liquid 28, preferably the same as the liquid refrigerant utilized in the system.

A compression spring 29 is utilized to provide a substantially constant force in a direction to reduce the volume of the space 26. For this purpose the lower head member 25 is shown as having a cylindrical portion forming a guide for the upper end of the spring 29. The lower end of the spring 29 is shown as guided by the cylindrical portion 30 of an abutment 3|. This abutment 3I is shown as adjustable to adjust the force exerted by the spring 29. For this purpose an adjusting screw 32 is provided, having a conical tip 33 engaging in a shallow conical seat 34 in the lower end of the member 3I.

Screw 32 is shown as threaded through a threaded aperture in a boss.35 depending from slot 39 for the accommodation of a screw driver to facilitate adjustment of the screw. Furthermore, the screw and gland arrangement may be sealed by the aid of a cap 40 threaded over the boss 35. The upper surface 4| of this cap may be made flat to cooperate with the tapered sealing flange 42 provided around the threaded boss 36. The cap 40 may be provided with a hexagonal portion 43 to facilitate removal and replacement thereof.

When the temperature of the refrigerant in chamber l8 increases, a corresponding increase in temperature is reached by the body 28 of liquid refrigerant in the space 26. Since this space 26 is closed, the vapor above the liquid 28 is constantly in a saturated condition, and accordingly the pressure within the space 26 corresponds to the vapor pressure at the temperature under consideration. This pressure exceeds that in the chamber I8, as the refrigerant in chamber I8 is superheated. Accordingly the member 2| tends to expand downwardly.

This expansion is opposed by several major factors. One is the pressure exerted on the bottom of the member 2| by the refrigerant in chamber I8; and the other is the force exerted by the spring 29. By appropriate adjustment of the spring force, by operation of screw 32, the amount of superheat required to cause a controlling expansion of the member 2| may be determined.

The inner surface of the inner bellows 24 is exposed to atmosphere by way of the central opening in ring 22, and a vent 44 located in a cover 45 for the device l2. As explained in the said prior William A. Ray application, by appropriate choice of the diameter of the members 2| and 24 the control may be made to respond at a definite degree of superheat, although the absolute temperature of the refrigerant in space I8 may vary.

The downward expansion of bellows structure 2|-24 is made use of to operate a control arm 46. This control arm is shown as pivoted by the aid of ear 41 projecting inwardly from the upright wall 48 of the member l2. This arm 46 is urged in a clockwise direction, or upwardly, by an appropriate torsion spring 49. The expansion of the bellows 2| exerts a force opposed to that of spring 49. This is accomplished by the aid of a saddle 50 having a knife edge contact with the upper side of the arm 46, and shown in this instance as formed integrally with a rod or link 5|. This rod 5| is appropriately supported as by the pivot pin 52 supported on the upper side of the head member 25. If desired, a stop 53 may be provided at the upper end of the rod 5| to limit the expansion of the member 2|.

The greater the superheat, the farther will the arm 46 be pulled downwardly against the action of the spring 49. Ultimately, this action may be suflicient to cause the valve structure 3 shown in Fig. 1 to open for the admission of refrigerant into the evaporator 2. Evaporation of the added refrigerant reduces the superheat, and this admission of refrigerant continues until the degree of superheat is insufiicient to cause arm 46 to be maintained in the valve controlling position.

The manner in which the valve structure 3 is constructed and operated by an electromagnetic force will be described hereinafter.

What has been said in connection with the operation of the arm 46 applies when the system is operating normally, in response to the action of a controlling thermostat. At times, as for example when the refrigerator unit has been inactive for an extended period, or when the unit 6 is first installed, the degree of superheat in chamber |6 is excessive, and much higher than encountered in normal operation. The opening of the valve 3 for a period sufllcient to reduce this superheat would permit an excessive amount of refrigerant to be admitted to the evaporator 2. This flooding of the evaporator should be prevented during this period of operation; and instead it is highly desirable that a very gradual supply of the refrigerant be provided, topermit the rate of evaporation of the refrigerant to be comparable with the rate at which it is supplied.

Accordingly the arrangement is such that upon an excessive expansion of the member 2|, corresponding to abnormal superheat, controlling actions are produced that sharply reduce or restrict the supply of refrigerant to the evaporator 2, until such time as the degree of superheat approaches normal.

The manner in which this is accomplished may be most readily understood in connection with Figs. 1, 3 and 5. Arm 46 (Fig 5) carries at its left hand end a contact post 54. This contact post is insulated as by an insulation bushing 55 from the arm 46. It is provided at its upper end with a contact point 56 and at its lower end with a contact point 51. The contact 56 during normal operation of the system is intended to be in con stant contact with a contact member 58 mounted on a resilient arm 59. The circuits controlled by these contacts will be described hereinafter.

The lower contact point 51 is arranged to make contact with a cooperating contact point 69 carried by flexible arm 6|. The contact post 54 is joined as by terminal 62 and flexible leads 63 to a terminal member 64.

The flexibility of arm 59 is such that during normal operation of the system as heretofore stated, the contact points 56 and 58 remain constantly in engagement. Upon an increase in the superheat, the contact points 51 and 69 may also engage, thereby completing two circuits, causing operation of the valve structure 3 to admit refrigerant to the evaporator 2. When the superheat decreases sufficiently, contact points 51 and 69 are disengaged, and admission of refrigerant is stopped.

The contact arms 59 and 6| as well as the terminal arm 64, are supported by the aid of the wall 65 of the device l2 and are insulated from each other as well as from the wall 65. Thus insulation blocks 66 may be arranged as spacers in a slot in the wall 65 to maintain the arms 59, 6| and 64 in the position illustrated in Fig. 5. Screws 6'! insulated from these arms and passing through the blocks 66, serve to attach these parts to the wall 65. The cover plate 45 encloses the controlling contacts as Well as the arm 46. This cover plate may be held in place as by a number of cap screws 68 engaging appropriate threaded apertures in the upright walls 48 and 65 of the device l2.

Contact points 56 and 58 control a circuit causing operation of the valve 3, by energization of the electromagnetic coil 69 (Fig. 3). This coil 69 when energized serves to maintain a passage in valve structure 3 open, and capable of passing liquid refrigerant into the evaporator 2. There is another passage in series, which is opened only upon engagement of contact points 51 and 66. These two passages being in series arrangement, both sets of contact points 56-58 and 5l-6l must be in engagement to permit passage of the refrigerant to the evaporator. Furthermore, the energization of coil 69 is also controlled by the thermostat or temperature responsive switch device 18 illustrated in Fig. 1. This switch device is shown as connected to one side of a source of electrical energy, such as a battery 1|. Its other terminal is connected by a lead 12 to the arm 84.

The circuit for the coil 69 may be traced as follows: from ground 13, battery 1I, switch 18, lead 12, arm 84, connection 83, terminal 82, contact points 55 and 58, arm 59, connection 14, coil 89, to ground 15.

When contact is established between contact points 51 and 68, a similar electromagnetic coil 18 (Fig. 3) is energized if the temperature responsive switch 18 is closed. The circuit for the electromagnet coil 18 may be traced as follows: from ground 13, battery 1|, switch 18, lead 12, arm 64, connection 63, terminal 62, contact points '81 and 68, arm GI, connection 11, coil 16, to ground 18.

As heretofore stated, energization of these electromagnets 69 and 16 permits the admission of refrigerant to the evaporator 2. How this is accomplished may be understood in connection with the description of the valve structure illustrated in Fig. 3.

This valve structure includes a body 19 shown conveniently as a casting. At the right hand side of the body 19 there is provided an inlet boss 88, into which is threaded the conduit 6 connected to the outlet side of thecondenser 1-8. At the left hand side of the body 18 a corresponding outlet 4 is indicated into which is threaded the conduit connected to the inlet of the evaporator 2.

An intermediate wall BI is shown, having a vertical port 82. In order for the refrigerant to pass from the inlet 88 to the outlet 4, it is necessary for it to pass through this port 82. The port 82 is controlled by a valve structure operated by the electromagnet 16. A boss 84 is shown as extending upwardly from the wall 8| and internally threaded for the accommodation of a seat forming member 83. This seat forming member 83 is provided with a sealing flange 85 adapted to cooperate with the upper surface of the boss 84. Through the member 83 extends a port 86 which is in communication with the port 82. The upper end of this port 85 is provided with a valve seat 81. tapered to cooperate with the lower surface of a closure member 88.

As shown most clearly in Fig. 4, the member 83 is provided with a plurality of rests 216. Accordingly the closure member 88 may be accommodated in the horizontal position illustrated in Fig. 3 by resting upon the seat 81 and the rests 216.

The upper flange of the member 83 (Fig. 4) may be interrupted as indicated at 89 to facilitate assembly or removal of the member 83 with respect to the boss 84.

The closure member 88 is made from magnetic material so as to be attracted by magnetism induced by the electromagnet coil 16. It may be provided with through apertures I88 adjacent its edge, to ensure free movement of the disc in the fluent medium controlled by the valve.

The electromagnet coil 16 is shown as disposed in the annular space between a central magnetic core 98 and an annular flange 9| of magnetic material. This flange 9| is shown as formed integrally with -a wall 92 into which the upper end 93 of the core 98 may be threaded. The lower end of the flange III is shown as provided with a shoulder 94 over which a clamping ring 95 is disposed. This flange 9| is shown as telescoped in the main boss 96 of the body 19 and is held in position by the clamping ring 95. A sealing metal disc 91 is shown disposed on the shoulder on which the lower end of the annular ring 9| rests. Furthermore, a metallic non-magnetic washer 88 may be provided to maintain the coil 18 in place. In this way the interior of main boss 96 is maintained fluid tight.

Conveniently the outer annular ring 9I may be continued to form an upwardly extending hollow boss 99 into which the ends of the coil 18 may extend. One end is connected to the ground 18 and the other lead is connected to the post III. This post I88 is connected to the conductor 11 by the aid of a separable coupling device IN. The stationary part of this coupling device IN is shown as provided with a flange I82 clamped between the top of the boss 98 and the lower end of a cap I83. This cap I83 is shown as screwed over the externally threaded projection of the boss 98.

The closure member 88 is shown in valve closing position. It is urged toward closing position by the aid of a compression spring I84. The bottom of this compression spring I84 is accommodated in the bottom of a spring cage I85 fastened in a central aperture in the closure 88. The upplained, the closure member 88 is lifted. Since The upper edge of the valve seat is shown as port 86 is eccentric with respect to the closure 88, the opening force acts to tilt the closure. This tilting is limited by the aid of an upwardly extending tilt-limiting flange I81 shown as formed integrally with the member '83. In this way excessive angular deviation of the closure member 88 from the horizontal is prevented, with attendant reduction in wear of the valve seat 81.

The refrigerant, when the valve closure 88 is lifted by the energization of coil 16, can pass through the horizontal passage I89, the connecting vertical port II8, into the hollow boss 98, thence through port 86 and into the central port 82. Further control of the admission of the refrigerant is provided by the electromagnet 68 and its associated valve parts. These valve parts are quite similar to the valve parts already described, except that they are arranged in reverse position on the other side of the wall or partition BI.

A central boss III extends downwardly from the wall 8I. It is internally threaded for the accommodation of a member II2 similar to member 83. This member H2 is threaded into the boss I I I so that the two annular sealing rings I I3 and. I I4 seat and seal upon the bottom surface of the wall 8|. Accordingly the annular space II5 between the sealing rings H3 and IN is segregated from the port '82. It is the function of the valve structure now to be described to establish communication between the port 82 and the annular passageway I I5.

For this purpose there is a port II8 located centrally of the member II2. Through this port the liquid refrigerant can pass from port 82, into a central recess II1 disposed in the lower face of the member II2, communicating with an outlet or port as hereinafterexplained. In order to reach the annular space I I5, the refrigerant must pass through port I I8 having the valve seat member H9 and arranged in general in a manner similar to that in member 83 illustrated in Fig. 4. Seat H9 is normally closed by closure member I20, similar to closure member '88. This closure member is urged upwardly to the closed position shown by the aid of a compression spring I2I arranged similarly to the compression spring I04. The electromagnet frame I22 includes the annular magnetic flange I23 held in fluid tight relation to the hollow boss I24 as by the aid of the clamping ring I25. One terminal of the coil 69 is connected to a grounded connection and the other terminal is connected to the conductor 14.

The compression spring I 2I is strong enough to maintain the valve closure I20 in the closed position indicated. However, when the coil 69 is energized, the closure member I20 is pulled downward, and tilts about seat H9; liquid refrigerant can then pass through the port I I8 upwardly into the annular passageway I I5.

In order, therefore, for the refrigerant to reach the annular space II5, both of the valve closures 88 and I20 must be attracted by the respective operating electromagnets.

From the annular space II the refrigerant can flow through a sloping port I26 formed in the body 19. This port extends into the aperture I21 formed in a boss I 28 on the valve body. From this aperture the refrigerant can flow through a number of radial apertures I29 disposed in a hollow orifice-defining member I 30. This member I30 is generall cylindrical and is seated upon a shoulder I3I around a port or passage I32. This port or passage I82 is in communication with'the evaporator 2 as by the aid of the port I33.

The member I30 is provided with an axial orifice I34 for passing the refrigerant from the inside of the member I30 into the port I 32. This orifice I34 is quite large, and offers little resistance to the flow of the refrigerant.

Member I30 is urged into fluid tight seating relationship with the seat I3I as by the aid of a compression spring I35. This compression spring is seated on a shoulder I36 on the inside of the member I 30. Its upper end is confined within a central aperture in a sealing cover I31 threaded into the boss I28. This sealing cover I 31 has a threaded extension I38 that cooperates with threads in the aperture I21. This extension telescopes over and guides the orifice defining member I30. This cover I31 may be provided with a sealing flange I39 cooperating with the upper surface of the boss I28.

During normal operation of the control device I2 (Fig. 5), contact points 56 and 58 are mengagement at all times. This therefore ensures that the electromagnet coil 69 is energized whenever the temperature responsive switch closes. However, no refrigerant can yet pass, since the refrigerant can not pass the closure member 88 unless the electromagnet coil 16 is energized. This occurs when contact point 51 engages contact point 60. Under such circumstances and in normal operation, both of the electromagnetic coils 16 and 69 are energized and the flow of refrigerant occurs as just described, through the orifice I 34..

Upon occurrence of abnormal superheat, the expanding bellows member 2| (Fig. 5) continues to expand until contact points 56 and 58 separate, while maintaining contact points 51 and 60 in engagement. Under such circumstances, the electromagnet coil 69 is deenergized and the valve closure I seats in theclosed position indicated in Fig. 3. Therefore the passage of refrigerant through annular passage H5 is prevented.

001116 is still energized, and a very restricted flow of refrigerant is nevertheless by-passed around the orifice I3 This by-pass can be traced as follows: past the closure 88, through ports 86, 82, and H6, into hollow boss I24, passages I40, I, to the interior of an aperture I42. This aperture is disposed in a boss I43. An orifice defining member I44 is seated on a shoulder I45 disposed around the lower end of the port I32. The refrigerant can flow through the radial apertures I46 into the interior of the member I44 and thence through the restricted orifice I41 through the ports I32 and I33 to the outlet 4. As before, the member I44 is in the form of a sleeve guided in the extension I48 of the cover I49. The member I44 is held in fluid tight seating relationship with the shoulder I45 by a compression spring I50 that operates in the same manner as compression spring I36.

Accordingly when contact is ultimately broken between the points 56 and 58 (Fig. 5), only a restricted flow of refrigerant is admitted to the evaporator 2.

There are three operative conditions represented by three alternative positions of the bellows 2I and of the control contacts. In the first position, illustrated in Fig. 5, there is a complete stoppage of the flow of refrigerant, because points 51, 60 are disengaged, and valve closure 88 is seated. In the second position, in which all of the contact points are in engagement, the valve closure 86 is lifted, and the valve closure I 20 is also in open position. Accordingly, refrigerant can pass freely through the orifice I34. In the third alternative position, in which contact points 51 and 60 only are in engagement, the closure I20 is in the closed position, and closure member 88 is in the open position. Under such circumstances, a restricted flow of refrigerant is permitted through the oriflce I41.

This restricted admission of the refrigerant is necessary as heretofore stated, when the system is first installed or after a protracted period of inactivity. As soon as the superheat of the! refrigerant in chamber I8 approaches normal, the valve closure I20 is free to be opened upon energization through the thermo-responsive switch 10; and thereafter the system operates in a normal manner.

As illustrated in Fig. 1, the outlet side of the control device I2 is connected as by conduit II to the intake side of compressor I0. It may happen that due to frequent admissions of refrigerant under abnormal temperature conditions, the pressure in the intake side of the compressor may reach an undesirably high value. This would result in an overloading of the compressor and of the system as a whole. Means are provided in connection with the control device I2 to limit the admission of refrigerant in the event this back pressure becomes abnormal.

Thus as shown in Fig. 5, a collapsible metal bellows member I5I is additionally provided in chamber I8. This metal bellows has its exterior surface exposed to the pressure of refrigerant in the space I8. Its interior is open to the atmosphere through an aperture in a cover member I52. This cover member operates with a flange ring I53 joined to the upper end of the member I5I. Screws I54 serveto seal the flange I53 to the wall IS.

A compression spring I55 is disposed within the member I5I. Its upper end abuts the lower surface of the cover I52. Its lower end is guided by cylindrical foot member I56. To this foot member is joined an operating upright member 11 I51 that extends through the cover I52. Stops I58 and I59 are carried by the member I51 to limit the extent of vertical movement of the member I51.

By proper proportioning of the spring I55, the arrangement may be such that upon excessive pressure being exerted by the refrigerant in chamber I8, the member I51" contacts the arm 46 and can overcome the pull exerted on the arm by the saddle 50. This ensures that the contact 1 members 51 and 60 separate,.and there occurs a consequent deenergization of the coil 16. As heretofore explained, this interrupts the supply of refrigerant. The admission of refrigerant can not be resumed until after the pressure in space I8 is sufficiently reduced to lower member I51 out of engagement with control arm 46.

In the system just described, the electromagnetically operated valve structure 3 is shown as comprising a pair of units, both of which are closed when deenergized, and opened by the energization of electric operating circuits.

An alternative system is illustrated in Fig. 2. In this case the valve units are shown separately as valves I60 and I6I, arranged in series relation. Valve I60 is illustrated in Fig. 10 and valve I6I is illustrated in Fig. 9. The control device I62, operating analogously to the control device I2, is shown in the same relative position to the cooling unit I.

In this instance, the control device I62 (Fig. 6) is provided with a control arm I63, similar to control arm 46 in Fig. and operated in the same manner by the saddle member 50 and the upright member I 51.

During normal operation of th system, the superheat control member operatin through the saddle 50 will move arm I63 so as to cause engagement and disengagement of a pair of contact members I64 and I65. Contact member I64, carried on the bottom of a post I 66, is insulatingly supported on the arm I63. The contact point I65 is carried by a flexible arm I61. Contact point I64 is connected as by terminal I68, flexible lead I69, contact bar I and conductor IN, to one side of the temperature responsive switch 10. The contact point I65 is connected through the flexible arm I61 and conductor I12, to the electromagnet coil I13 (Fig. 9) of the valve structure I6I.

I13 is grounded in a manner described in connection with Fig. 3.

Accordingly when there i a sufficient degree of superheat warranting admission of refrigerant to the evaporator 2, the electromagnet coil I13 may be energized through the following circuit: ground 13, battery 1I, switch 10, conductor I1I, arm I10, connection I69, terminal I68, post I66, contact point I64, contact point I65, arm I61, conductor I12, coil I13, and ground I 14 (Figs. 2, 6 and 9).

Upon energization of coil I13, liquid refrigerant is permitted to pass through the valve I6I, and through the normally open valve I60.

The valve structure I 6I is illustrated in Fig. 9. Conduit 6 is threaded into the inlet boss I14 of the valve body I15. Thence the refrigerant can pass through port I16 to a space I11 surrounding a central boss I18. This central boss accommodates a seat forming member I19 having the same general structure as the member 83 of Fig. 3. This member I19 is provided with an eccentric port I80. The upper portion of the port is The other terminal of the coil formed bythe valve seat member I8I. This valve seat member is normally closed. by the valve 12 closure I82 having the same general structure as the valve closure 88 of Fig. 3. This valv closure I82 is adapted to be attracted to open the port I when the coil I13 is energized. When the port is open, refrigerant can pass downwardly through the port I and into a passageway I84. This passageway I84 passes the refrigerant through a series of radial apertures I85 arranged in the orifice'forming member I86. This orifice forming member I86 is similar in structure to the orifice forming member I30 of Fig. 3. It is provided with an orifice I81 passing the liquid refrigerant into passageways I88 and I 89 to the out-- let boss I90. The orifice forming member I86 is urged against its seat by a, compression spring I9I held in place by the cover member I92. This cover member I92 may seal against the lower surface of a boss I93in which the orifice forming member I86 is accommodated.

The orifice I81 is quite large and is capable of passing the refrigerant at a rapid rate into the evaporator 2.

Upon the occurrence of a limiting degree of superheat, the control arm I63 continues its downward movement and contact is made between contact point I94 and contact point I95 (Fig. 6). Contact point I94 is formed on a post I96 that is insulatingly supported on the arm I63. It is likewise joined to the terminal I68. Engagement of contact points I94, I 95 occurs only after points I64, I65 are in engagement,.

since these points I94, I95 are normally separated by a greater distance than contact points I64, I65.

Contact point I95 is carried by a flexible arm I91 connected to a conductor I98. The arms I61, I10 and I91 may be supported on a wall of the control device I62 generally in the same manner as illustrated in connection with Fig. 5. Conductor I98 forms a part of the circuit for energizing the electromagnet coil I99 (Fig. 10) of the valve I60. Thus upon excessive superheat, contact points I94 and I95 may serve to complete the circuit of the coil I99 and thereby cause closing of the valve I60. This closing of the valve, however, permits a restricted bypass to supply liquid refrigerant at a greatly reduced rate to the inlet side of the cooling unit I.

The structure of the valve I60 is illustrated in Fig. 10.

The inlet boss 200 is shown as connected to the conduit 20I that leads from the outlet side of the valve I 6I. The outlet boss 202 i shown as connected to the conduit 203 joined to the inlet side of the cooling unit I. The general structure of the electromagnet I99, its frame 204 and connection means 205, is similar to th corresponding parts of the valve operating means 11- lustrated in Fig. 3 and no further description is therefore necessary.

Under normal conditions, with the electromagnet coil I 99 deenergized, the armature 206 is in the dropped position illustrated. This armature 206 is urged toward dropped position by the compression spring 201 disposed in the cage 206. The upper end of the spring 201 abuts the flange of a guide member 209 joined to the metallic disk 2I0, similar to disk 91 of Fig. 3. The lower end of the spring 201 is guided by,the head of the valve operating rod 2I2 that passes through the bottom of the cage 208. In the deenergized position of Fig. 10, this member 2I2 is active to maintain the valve in open position.

However, when the coil I 99 is energized due to the engagement of contact points I84, and

I95, (Fig. 6) the disk armature 206 is attracted,

13 and the valve is permitted to close. This disk armature 206 is shown as guided in the main boss 2I3 of the valve body 2.

The valve body 2 is provided with a transverse horizontal wall 2I5. In this wall is threadedly engaged a valve seat forming member 2| 6. This member is shown as having a tapered sealing flange 2I1 engaging the lower surface of the wall 2I5. It is also provided with a central port 2I6. The lower end of this port 2I8 accommodates a valve seat member 2I6.

Adapted to cooperate with this valve seat member 2 I 9 is a closure member 220. This closure member is of general disk-like configuration and is guided in the downwardly depending boss 22I. It may be provided with a series of apertures 222 adjacent the outer edge thereof. The member 2I6 may further be provided with a downwardly extending flange 223 to limit the tilt of the closure member 220.

The weight of the armature 206 and the force of compression spring 201 are imposed upon the closure member 220 by the aid of the closure operating rod 2| 2. For this purpose this closure operating rod 2I2 is provided with a pointed extremity 224 engaging in a shallow recess 225 in the upper face of the armature 220. Spring 201 overcomes the force of a. relatively light compression spring 226 acting upwardly against the lower side of the closure 220. The upper end of this compression spring 226 is accommodated in a shallow recess in the lower side of the closure 220. The lower end is shown as guided in a shallow recess in a closure cap 221. This closure cap is threaded into the boss 22I. It is provided with a tapered sealing flange 223 cooperating with the lower surface of the boss 22I.

When the coil I99 is deenergized, the parts assume the position illustrated in Fig. 10; that is. the closure member 220 is depressed and t e port 2I6 is open. When the electromagnet coll I99 is energized, the spring 226 is free to urge the closure member 220 to a closed position.

The flow of refrigerant through alternative restricted and unrestricted paths may now be traced between the inlet conduit 20I and the outlet conduit 203. Thus the inlet conduit 20! passes the refrigerant through a passa eway 229 which communicates with an aperture 230. This aperture 230 accommodates an orifice iormin' member 23I. This orifice forming member 2! is seated upon a shoulder 232 disposed around the passage 233. This passage 233 leads into the central space 234 in boss 2I3. This space 234 is in communication with the outlet conduit 20? by way of the passageway 235.

The orifice forming member 23I is provided with a restricted orifice 236 and with the radial openings 231. Accordingly whether or not the valve structure closure 220 is in open or closed position, refrigerant can pass through port 229, aperture 231, orifice 236, port 233, space 234 and port 235 to the outlet conduit 203.

The orifice forming member 23I is ur ed to seated position by the aid of a compression spring 238 confined in the cover member 239. This cover or cap 239 is threaded into the aperture 230 and is sealed as by the sealing flange 240 against the plane surface formed around the aperture 230.

In addition, when the valve is in the open position asindicated, refrigerant can pass around the orifice member 23I, into the passageway 2. .This passageway is in communication with the space 242 in which closure 220 is accommodated. Hence the refrigerant can flow upwardly through the port 2 I6 to the space 234, passageway 235 and outlet conduit 203.

The contact points I94 and I95 of Fig. 6, as heretofore stated, do not engage until after engagement of contact points I64 and I65. In normal operation, only the contact points I64 and I65 engage and disengage. In the disengaged position shown, valve I is fully open and valve I6I is closed, thereby stopping all fiow of refrigerant to the cooling unit I. In the next alternative position, where contact points I64 and I65 are engaged, the valve I6I is opened, and since valve I60 is also opened, a free flow of refrigerant through both valves could take place. On a continued or abnormal rise of superheat, contact points I94 and I95 engage, energizing the electromagnet coil I99 of valve I60. This closes the main port 2I8 for the valve I 60, while the restricted path through the orifice 236 remains open. Therefore, under such circumstances, restricted flow of refrigerant is permitted. This continues until the superheat approaches normal value.

As before, excessive back pressure will cause the operating member I51 of Fig. 6 to move the arm I63 to the contact opening position. Under such circumstances, all flow of refrigerant is stopped, and this continues until the back pressure approaches normal.

In the form of the invention illustrated in Fig. 1, control device I2 has been described which operates normally to maintain the degree of superheat below a definite limit. This is accomplished by the aid of a double walled control member 2I-24, so arranged that vapor pressure in the space 26 opposes the pressure of the refrigerant in space I8. When this vapor pressure is sufliciently great, the control arm 46 is operated to cause contact points 51 and 60 to engage and thereby to permit refrigerant to enter the cooling unit. In this arrangement it has been pointed out that the vapor pressure within the space 26 is effective over an area less than that exposed to the pressure of the refrigerant in space I6. This differential area is represented by the cross sectional area of the inner bellows member 24. By appropriate proportioning of these parts, the degree of superheat at which the control operates depends upon the adjustment of spring 29, and is substantially independent of the absolute temperature of, the refrigerant.

In the form of the control device illustrated in Figs. 7 and 8, a special bellows arrangement is provided to perform the functions of both of the bellows arrangements 2I-24 and I5I illustrated in Fig. 5. The manner in which this is accomplished will now be described.

Insofar as the contact points 56-58 and 5160 are concerned, they operate identically as described in connection with the form of the invention illustrated in Fig. 5. In this instance however the control arm 243 that carries the contact points 56 and 51, is operated in a manner somewhat difierent from that illustrated in Fig. 5.

The control arm 243 is shown as pivotally supported at 244 on the vertical wall 48 of the casing 245. As before, the refrigerant enters the device by way of conduit I3 and port 246. The refrigerant passes from the device by way of port 241 and conduit II. A chamber 246 is formed through which the refrigerant passes on its way to the intake side of the compressor l0.

Arm 243 has several forces imposed thereon.

. One force is transmitted by the control member 249 which is in the form of a corrugated metal bellows. The exterior surfaces of this bellows member 249 are exposed in the chamber 248 to the pressure of the refrigerant therein. The upper edge of the member 249 is sealed to the flange 250 fastened to the wall !9. This can be accomplished by aid of a cover member and the screws 252. The cover member 25! is apertured so that the interior of the bellows member 249 is open to the atmosphere.

A compression sprin 253 is accommodated within the member 249. It exerts a force tending to expand the member 249 downwardly. For this purpose its upper end abuts the lower surface of the cover 25! and its lower end is guided by the head 254 closing the lower end of the bellows member 249.

Pivotally connected to the upper side of head 254 is a link 255 operatively connected to the arm 243.

Normally the force of the spring 253 is sufficient to overcome the fluid pressure exerted on the exterior surface of the member 249. However,

contact points 56 and 58 are nevertheless kept in engagement by virtue of a lever mechanism. This mechanism includes lever 256. This lever 256 is pivoted on a pin 251 (see also Fig. 8) that extends across a recess 259 in a wall of the casing 245. This pin 251 is shown as for-med integrally with a headless screw 259 threaded into an aperture aligned with the axis of the pivot pin 251. A sealing cap 260 may be utilized to ensure a fluid tight structure.

The upper portion of the lever 256 is provided with a knife edge 26! which engages a shallow recess in the bottom of the head 254. This lever 256 is urged in a clockwise direction by a compression spring 262, thereby restricting downward motion of bellows 249. Compression spring 262 has its upper end guided in a head 263. The upper side of the member 263 is provided with a knife edge 264 operating upon the lower side of the lever 256.

The lower end of the spring 262 is guided by a head 265 adjustable by a screw 266. This screw 266 is similar in structure to the screw 32 illustrated in Fig. 5. A cover 261 similar to cover 46 of Fig. 5 may be provided.

The force of spring 262, under normal conditions of operation, is sufficient to overcome that of spring 253, and contact points 56 and 58 remain in engagement.

There is an additional force urging the lever 256 in a counterclockwise direction. This force is transmitted by the aid of a bellows member 268. This bellows member is non-coaxial with, and spaced from the bellows member 249. Member 268 is sealed to a cover 269, in turn attached to the wall l9. In this bellows member 268 is located a volatile liquid 210, preferably the same as the liquid refrigerant.

Accordingly, the pressure within the bellows device 268 corresponds to the vapor pressure of the refrigerant at the temperature existing in the space 248.

The lower end of the member 268 is attached to a head 21!. This head 21! is provided at its lower side with a shallow recess 212. In this recess is engaged a knife edge 213 carried by the upper side of the lever 256.

When the vapor pressure in the space 214 enclosed by the bellows member 268 is sufliciently increased, it overcomes the force of spring 262 sufliciently to urge the lever 256 downwardly. This downward movement of the lever 256 perl the superheat approaches a normal value.

16 mits the spring 253 in bellows 249 to urge the bellows downwardly to follow the downward motion of the lever. Upon a sufiicient vapor pressure being exerted within the space 214, contact members 51 and 60 are engaged, and refrigerant is admitted to the cooling unit By appropriate proportioning of the effective area of the bellows 249 and 268 that are exposed to the pressure exerted in the chamber 248, the degree of superheat required to cause contact members 51 and 60 to engage can be kept substantially constant, even when the absolute temperature of the refrigerant varies.

Upon an excessive degree of superheat, the vapor pressure in space 214, lowers lever 256 sufficiently to permit the spring 253 to lower the arm 243 sufliciently to disconnect contact points 56 and 58. Under such circumstances as hereto explained, the flow of refrigerant is restricted, since then it must pass through the restricted orifice I41 of Fig. 3.

In the event of excessive back pressure existing in the chamber 248, this pressure operating on the external surfaces of the bellows member 248 is sufficient to overcome the pressure of the spring 253, and head 254 may rise out of contact with the lever 256; this causes arm 243 to assume the position illustrated in Fig. 7; that is, the flow of refrigerant to the cooling unit stopped.

By the arrangement illustrated in Fig. 7, normal operation of the system to admit refrigerant into the cooling unit occurs while neither the superheat nor the back pressure reaches an undesirable high value. When excessive superheat occurs, the flow of refrigerant is restricted until This is accomplished by opening of the contacts 56 and 58 and maintaining contacts 51 and 60 closed. In the event of excessive back pressure, however, the contact points are maintained in the position illustrated to ensure complete shutting off of the refrigerant until normal back pressure conditions are approached. At the same time, by appropriate proportioning of the area of the members 249 and 268 that are exposed to the pressure in chamber 248 and by appropriate relative proportioning of the lever arms to which these two members operate upon the lever 256, the degree of superheat permitted by the system can be maintained within close limits.

The systems illustrated generally by Figs. 1 and 2 are intended to be utilized for air conditioning of relatively large spaces, represented by compartment 280. These systems are, however, useful as well in connection with refrigeration systems for the preservation of food, etc., where the temperature in a compartment is desired to be kept near freezing.

In such refrigerating systems, frosting often occurs because the normal temperature range of the cooling unit has lower and upper limits of about 15 F. and 36 F. respectively. In this way, frost is permitted to form while the temperature of the unit is at or near the lower limit. Frost being a heat insulator, its accumulation on the unit reduces the efliciency of the unit.

One way in which the advantages of the present invention may be attained in a food refrigerating system, without material accumulation of frost, is illustrated in Fig. 11. This is generally the same as that. illustrated in Fig. 1; compartment 28! is intended to represent a space where a temperature near freezing is to be maintained. Provisions are made in the present inis entirely I stance to stop operation of the system when the cooling unit reaches a temperature of about 32 Pt, and thereby to reduce the formation of frost.

To obtain this result, a supplemental thermostat switch 282 isplaced in series with switch 10. This thermostat is placed inside the unit I, or outside it, between the fins. In this way. itresponds to the temperature of unit I. Thermostat 282 opens the circuit when a temperature of say 32 F. is reached by the unit I. This temperature is not low enough to produce substantial frosting. The normal range may therefore be. quite narrow; the upper limit being defined by switch 10 may be about 36. The limits are therefore from about 32 to 36. With such narrow limits, frosting is substantially entirely eliminated; the emciency of the system is increased, although a larger unit I is needed than with a wider range of operation.

When such an additional thermostat 282 is used, the pressure responsive switch I6 is no longer relied upon for defrosting. It should be set to keep compressor l operating at lower pressures at the compressor inlet than in the system illus- .trated in Fig. 1. In this way, short-cycling" or the compressor is avoided.

What is claimed is:

1. In a refrigerator system utilizing a vaporizable refrigerant, an evaporator, an electrically operated valve structure controlling the admission ofv refrigerant to the evaporator, said valve structure including means capable of assuming any of three settings corresponding first to an interruption in the supply of refrigerant to the evaporator, second to the free admission of refrigerant to the evaporator, and lastly to a restricted admission of refrigerant to the eva orator, and an electrical control means for causing said valve structure to assume the proper one of said settings in response to a variation in a function of the temperature of the refrigerant in the evaporator.

2. In a refrigerator system utilizing a vaporizable refrigerant, an evaporator, an electrically operated valve structure controlling the admission of refrigerant to the evaporator, said valve structure including means capable of assuming any one of three settings corresponding first to an interruption in the supply of refrigerant to the evaporator, second to the free admission of refrigerant to the evaporator, and lastly to a restricted o superheat reaches said higher value.

. 3. In a refrigerator system utilizin a vaporizable refrigerant: an evaporator; electrically operated means for controlling the admission of refrigerant to the evaporator, said means having movable valve elements that together can assume such positions as toconform to any one of three combinations of positions, said positions of each element corresponding to limits of motion of said elements whereby such positions are stable, one combination of positions substantially entirely stopping the admission of refrigerant, another combination permitting a normal rate of admission, and the third combination restrictin the rate of admission; an electric circuit for operating amuse 18 said controlling means; and a circuit controller for said circuit and comprising sets of contacts constructed and arranged to assume positions conforming to any one of three combinations of positions, in response to variations in a function of the temperature of the refrigerant in the evaporator, and selectively causing said three combinations of the electrically operated means to be effected.

4. In a refrigerator system utilizing a vaporizable refrigerant: an evaporator; electrically operated means for controlling the admission of refrigerant to the evaporator, said means having movable valve elements that together can assume such positions as to conform to any one of three combinations of positions, said positions of each element corresponding to limits of motion of said elements whereby such positions are stable, one combination of positions substantially entirely stopping the admission of refrigerant, another combination permitting a normal rate of admission, and the third combination restricting the rate of admission; an electric circuit for operating said controllin means; a circuit controller for said circuit; and means for operating said circuit controller to cause said means for controlling the flow of refrigerant to assume said three combinations of positions progressively and in succession in response to a variation in one direction in function of the temperature of the refrigerant in the evaporator.

5. In a refrigerator system utilizing a vaporizable refrigerant: an evaporator; electrically operated means for controlling the admission of refrigerant to the evaporator, said means having movable valve elements that together can assume such positions as to conform to any one of three combinations of positions, said positions of each element corresponding to limits of motion of said elements whereby such positions are stable, one combination of positions substantially entirely stopping the admission of refrigerant, another combination permitting a normal rate of admission, and the third combination restricting the rate of admission; an electric circuit for operating said controlling means; a circuit controller for said circuit; and means for operating said circuit controller to cause said means for controlling the flow ofrefrigerant to assume said three combinations of positions progressively and in succession as the degree of superheat of the refrigerant in the evaporator increases.

6. In a refrigerator system utilizing a vaporizable refrigerant: an evaporator; electrically operrated means for controlling the admission of refrigerant to the evaporator, said means having movable valve elements that together can assume such positions as to conform to any one Of three combinations of positions, said positions of each element corresponding to limits of motion of said elements whereby such positions are stable, one combination of positions substantially entirely stopping the admission of refrigerant, another combination permitting a normal rate of admission, and the third combination restricting the rate of admission; an electric circuit for operating said controlling means; a circuit controller for said circuit; means for operating said circuit controller to cause said means for controlling the flow of refrigerant to assume said three combinations of positions progressively and in succession as the degree of superheat of the refrigerant in the evaporator increases; and means for independently causing said circuit controller to cause substantially complete stopping of the admission 19 of refrigerant in response to the attainment of an abnormal value in pressure of the refrigerant in the evaporator.

7. In a refrigerator system utilizing a vaporizable refrigerant: an evaporator; electrically operated means for controlling the admission of refrigerant to the evaporator, said means having movable valve elements that together can assume such positions as to conform to any one of three combinations of positions, said positions of each element corresponding to limits of motion of said elements whereby such positions are stable, one combination of positions substantially entirely stopping the admission of refrigerant, another combination permitting a normal rate of admission, and the third combination restricting the rate of admission; an electric circuit for operating said controlling means; a circuit controller for said circuit; means for operating said circuit controller to cause said means for controlling the flow of refrigerant to assume said three combinations of positions progressively and in succession as the degree of superheat of the refrigerant in the evaporator increases; and means for independently causing said circuit controller to cause ubstantially complete stopping of the admission of refrigerant in response to the attainment of an abnormally high pressure of the refrigerant in the evaporator.

8. In a valve structure, a valve body having at opposite ends, respectively an inlet passage and an outlet passage, as well as an intermediate wall having a port therethrough, means forming valve seats respectively on opposite sides of said port, and closures respectively for said seats, there being a passageway from the inlet to the first valve seat, said port being in communication with said passageway when the closure member cooperating with said first valve seat is moved off said first valve seat, said port communicating with another passageway controlled by the second closure, and communicating with the outlet passage, and there being a restricted by-pass between said port and said outlet passageway, said by-pass having an area less than said port.

9. In a refrigerating system utilizing a vaporizable refrigerant, an evaporator, electrically operated means for determining the rate of admission of refrigerant to said evaporator, a circuit controller for said means, said circuit controller having a movable switching element, means responsive to temperature conditions of the refrigerant in the evaporator, and in continuous co-operative relation to said circuit controller for moving said element, and means responsive to the pressure of the refrigerant in the evaporator for moving said element only upon the occurrence of abnormally high pressure.

10. In a refrigerating system utilizing a vaporizable refrigerant. an evaporator, electrically operated means for determinin the rate of admission of refrigerant to said evaporator, a circuit controller for said means, said circuit controller having a movable switching element, and means responsive to the pressure of the refrigerant in the evaporator for moving said element only upon the occurrence of abnormally high pressure.

11. In a refrigerating system utilizing a vaporizable refrigerant, an evaporator, valve means for adjusting the rate of admission of refrigerant into the evaporator, and a control mechanism for the valve means, comprising a movable arm, said arm having extremities of movement, corresponding respectively to substantially complete stopping of the admission of refrigerant, and to a restricted flow of refrigerant, said arm having an intermediate position corresponding to a free flow of refrigerant; a first member responsive to variations in fluid pressure of the refrigerant in the evaporator and connected to the arm to urge the arm in a direction toward the first extremity of movement; a lever arranged to exert a force on said member only in a direction toward said first extremity of movement; and a second member responsive to variations in the temperature of the refrigerant in the evaporator, and exerting a force upon the lever in a direction away from the said first member.

12. In a refrigerating system utilizing a vaporizable refrigerant, an evaporator, valve means for adjusting the rate of admission of refrigerant into the evaporator, and a control mechanism for the valve means, comprising a movable arm, said arm having at least two operating positions, corresponding respectively to substantially complete stopping of the admission of refrigerant, and to free flow of the refrigerant; a first member responsive to variations in fluid pressure of the refrigerant in the evaporator and connected to the arm to ur e the arm in a direction toward the first position; a lever arranged to exert a force on said member only in a direction toward said first position; and a second member responsive to variations in temperature of the refrigerant in the evaporator, and exerting a force upon the lever in a direction away from the said first member.

13. In a refrigerating system utilizing a vaporizable refrigerant, an evaporator, valve means for adjusting the rate of admission of refrigerant into the evaporator, and a control mechanism for the valve means, comprising a movable arm, said arm having at least two operating positions, corresponding respectively to substantially complete stopping of the admission of refrigerant, and to free flow of the refrigerant; a first member responsive to variations in fluid pressure of the refrigerant in the evaporator and connected to the arm to urge the arm in a direction toward the first position; a lever arranged to exert a force on said member only in a direction toward said first position; and a second member responsive to variations in temperature of the refrigerant in the evaporator, and exerting a force upon the lever in a direction away from the said first member, the forces upon the lever being such that the arm is controlled to reduce the rate of admission of the refrigerant upon the occurrence of a definite degree of superheat.

14. In a refrigerating system utilizing a vaporizable refrigerant, an evaporator, valve means for adjusting the rate of admission of refrigerant into the evaporator; and a control mechanism for the valve means, comprising an arm movable to a first position corresponding to substantially complete stopping of the admission of refrigerant, and to a second position corresponding to a free flow of refrigerant; a first member connected to the arm and movable in response to variations in fiuid pressure of the refrigerant in the evaporator, an increase in said pressure serving to increase the force exerted by the member to urge the arm toward said first position; and a second member responsive to variations in temperature of the refrigerant and. exerting a force supplementing the force exerted by said first member upon the arm, the supplementary force increasing as the temperature is reduced.

15. In a refrigerating system utilizing a vaporizable refrigerant, an evaporator, .valve means for 21 adjusting the rate of admission of refrigerant into the evaporator; and a control mechanism for the valve means, comprising an arm movable to a first position corresponding to substantially complete stopping of the admission of refrigerant,

in fluid pressure of the refrigerant in the evaporator, an increase in said pressure serving to increase the force exerted by the member to urge the arm toward said first position; and a second member responsive to variations in temperature of the refrigerant and exerting a force supplementing the force exerted by said first member upon the arm, the supplementary force increasing as the temperature is reduced, said forces being such that the arm is controlled to reduce the rate of admission of the refrigerant upon the occurrence of a definite degree of superheat.

HAROLD J. MA'I'IEBON.

22 nmmcns mm The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 762,249 Ott June 7, 1904 1,804,462 Eggleston May 12, 1931 1,853,273 Hofl'man Apr. 12, 1932 1,920,505 Henney Aug. 1, 1933 1,997,879 Watry Apr. 16, 1935 2,148,483 Philipp Feb. 7, 1939 2,167,399 Wagner July 25, 1939 2,195,220 McGrath Mar. 26, 1940 2,289,923 Miller July 14, 1942 2,296,322 Alfery Sept. 22, 1942 2,339,353 Ray Jan. 18, 1944

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