US2113345A

US2113345A - Refrigerant control device

Info

Publication number: US2113345A
Application number: US92217A
Authority: US
Inventors: Haymond Paul
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-07-23
Filing date: 1936-07-23
Publication date: 1938-04-05
Anticipated expiration: 1955-04-05

Description

April 5, 193.8. P. 'HAYMOND 2,113,345

REFRIGERANT CONTROL DEVICE Filed July 23, 1956 2 Sheets-Sheet 1 WQNH QNN NNN v gh.. h

PAUL HAYNOND April 5, 1938- P. HAYMoND SEFRIGERANT CONTROL DEVICE Filed July 25', 1956 2 sheets-sheet 2 Patented Apr. 5, 1938v I l I v UNITED STATES PATENT oi-FicE 'naralcaasnrlsi'sra nevica l raul namens, Fairmont, w. va. Application July 23, 1936, Serial No. 92,217

13 Claims. (Cl. 82--8l The present invention relates to a refrigerant valve controlling the flow of the refrigerant and to control device especially adapted for use in conimpose between the float valve and the refrigerant nection with the controlling of the refrigerant in supply of the condensing unit a conventional type the conventional compressor type refrigeration automatic expansion valve which will insure the system. feeding of the refrigerant to the evaporator at a 5 In refrigerating systems of this character the constant suction pressure at a predetermined setmethod of controlling the refrigerant is by what ting during the time the float valve is open. In is known as the low side float, the high side oat, other words, the present invention contemplates and the expansion valve. The low side float has the combination of the low side float control and the advantage of keeping the evaporator ooded the expansion valve in a novel manner to obtain 10 with the refrigerant at all times. However, this the advantages of each. advantage is somewhat offset 4by the variation of By combining the oat valve and the expansion suction pressures which Awhen decreased reduces valve, a system of refrigerant control is obthe capacity and efficiency of the condensing unit tained which has the advantages of completely l5 materially. 'I'he low side float simply permits flooding the evaporator with liquid refrigerant 15 enough refrigerant to enter the evaporator to and the advantages of the expansion valve by maintain a fairly constant liquid level. The resupplying the refrigerant at a constant suction frigerant is permitted to enter the evaporator pressure. The efficiency of the evaporator and under any pressure less than the liquid refrigthe condensing unit is greatlyincreased. In addierant pressure of the condensing unit. tion to increasing the efciency of the condenser 20 The expansion valve system permits the refrigandthe evaporator, this system also greatly reerant to flow into the evaporator at a constant duces the necessity of adjustments and service pressure below a predetermined setting. This typical to the expansion valve, evaporator resystem of control of the refrigerant permits frigerant control systems.

higher condensing unit capacity and efficiency. Other objects and advantages of the invention However, it is practically impossible to obtain the Will beQme apparent and in fact pointed Out in ideal Situation of having the evaporator in a the following detailed description taken in connooded condition without the spilling over of the nection with the accompanying drawings, whererefrigerant into the suction line, which causes in Corresponding reference numerals designate very inefficient operation. In this connection similar partsthroughout, and in which, 30

thermauegulators have been devised and are now Figure 1 is a vertical sectional view of the rein use which attempt to control the frost line on 4Illelii'llil eOIilll'Ol device, evaporators operated by expansion valves. Agas Figure 2 is a fragmentary vertical sectional charged bulb isclamped to the suction line and view of a modified form of the invention,

connected to a bellows which varies the tension .*Figure 3 is a longitudinal horizontal sectional 35 ofthe expansion valve actuating spring. The dis- View of Figure 2 taken on line 3--3` thereof,

advantage of this. system of oontromng the re- Figure 'i is a front elevational view of a still frigerant is that it is almost impossible to mainfurther mOdied form 0f the iuveuliu,v tain the flooded coil without frosting or refrigerat- Figure 5 is a detail fragmentary view partly 40 ing the suction line. in section of the form of invention illustrated in 40 It is therefore one of the objects of the present Figure '4, invention to provide a refrigerant controlling Figure 6 iS a curve 0f a refrigerator employing device 'which insures a 'flooded condition of the a straight float VelVeAeOutrOl, evaporator at'au times and which will insure Figure-'l is a curve of a refrigerator employing the feeding oit therefrigerant to the evaporator at an expansion valve, and: 45 a constant suction pressure at a predetermined Figure 8 is a curveof a refrigerator employing setting during the operation of the device. the type of valve forming the subject matter of A still further important object or the inventhe present invention. tion is to provide a refrigerant controlling device In the laccoviripanying drawings wherein for of this character which will maintain a more the pul'pOee 0f illllStratiOn there 1S Shown pre- 50 constant back pressure on the system of the comferred embodiments of the invention, vand repressor, evaporator type refrigerating system. ferring more particularly to Figure 1, .the refer,

The presentinvention contemplates the proence numeral 6 generally designates the evapo- 'vision of a. float valve having a snap action mechrating chamber which is employed in refrigeratanism to fully open and fully close the needle ina systems of the character previously described. 55

In the usual manner one end of the evaporator chamber is provided with a closure plate 8, having secured therein and projecting into the upper portion of the evaporator a conduit I8 which communicates with the tubing I2 connected to the condensing unit which is of standard design and construction. It will thus be seen that the evaporated refrigerant is transmitted to the condensing unit in this manner.

As will be observed, the closure plate 8 is provided with an inwardly projecting externally threaded nipple I4 having a longitudinally extending bore or passage I6 therein, the inner end of which has a valve seat I8. On the inner end of the nipple I4 there is screw-threaded a cap 20 having a laterally extending integral arm 22 to which there is pivotally mounted through the medium of the pin 24 the arm 26 carrying the float 28. Also pivoted on the pin 24 is an upstanding support 38 to which the outer end of the needle valve 32 is pivotally mounted, the inner end thereof, as clearly illustrated, cooperating withthe valve seat I8 to control the flow of refrigerantA from the passage I6 into the evaporator chamber 6. On the upper side of the arm 26 there is arranged an integral upstanding ear 34 to which there is securely fastened by means of the screw bolt 36 an upstanding arm 38. Anv armature 40 is securely fastened to the plvotally mounted arm 30 and has secured thereto and'extending laterally therefrom an L-shaped arm 42. Spaced from the depending leg 46 of the arm 42 is a second depending leg 48 between which the upstanding arm 38 is movable. The limit of travel of the upstanding arm 38 between the depending legs 46 and 48 is controlled through the medium of the adjustable set screws 58. To the. inner side of the closure plate 8 there is fastened a laterally extending arm 52 which has disposed on the free end thereof a magnet 54 and an L- shaped arm having a depending portion 56 spaced from the outer end thereof. It will thus be seen that the armature 40 is movable between the end of the magnet and the depending portion 56 of the L-shaped arm.

The refrigerant liquid is carried from the con. densing unit to the evaporator chamber 6 by A the tubing 56 which is connected to the shell 58 of the expansion valve 60 through .the medium of the connector 62.- (Extending laterally in the shell and communicating with the connector 62 is a closed end conduit 65 having a valve seat 66, the lower side thereof adjacent the closed end.) The flow of liquid from the conduit 56a and consequently through the valve seat 66 into the chamber 63 of the shell is controlled through the medium of an adjustable needle valve 68 cooperating with the valve seat and controlled in theusual manner by means of the sylphon 18. It will be seen that the sylphon is suspended centrally within the shell 58, the needle valve 68 being connected to the sylphon by means of a saddle arm 12. 'I'he upper portion of the sylphon 'I8 is not only securely fastened Within the shell 58, but is sealed against leakage through .the medium of the screw-threaded cap 14. Thus,

it will be observed that a pressure exerted on the sylphon 'I6 Will raise the saddle arm 'I2 and consequently the needle 68 closing the valve seat 66. Similarly, a reduction of pressure against the sylphon 'I0 will allow the spring 18 to close therein to lexert a pressure in the opposite direction and open the needle 68 in the valve seat allowing the refrigerant to pass from v I8 and the cooperating needle valve 32.

' armature 4U.

the tubing56 through the valve seat 66 into the chamber'63 of the expansion valve. Incidentally, it is to be noted that this operation is the usual operation of an automatic expansion valve which is commercially on the market today and can be adjusted by means of the set screw 86 to any predetermined pressure opening or closing desired. The expansion valve is connected by means of the conductor 82, as clearly illustrated, to the closure plate 8 which conductor is screw-y threaded therein and communicates with the passage I6 in the nipple I4.

It is to be noted that the liquid from the tubing 56 and in the conduit 66 is under the usual condensing pressure and maintained in liquid form. However, at the needle valve 68 andthe seat 66 a reduction in pressure is encountered and the liquid is turned into a vapor. This is the usual function of an expansion valve. However, the amount of liquid passed by the valve and the amount changed to vapor is entirely dependent upon the surrounding temperature, so that there are times when only a small portion of the liquid is turned into vapor. As the liquid and vapor pass through the chamber 63 of the expansion valve and the threaded connector 82 it comes in contact with the oat valve seat v Thus, it will be seen that the valve 32 controls the passage of the refrigerant from the expansion valve to the evaporating chamber 6. When there is a sumcient liquid to maintain a level such as indicated by the dotted line A the float 28 is raised on the pivot 24 through lthe medium" of the arm 26 which is pivoted thereto. It will be seen that a rising movement of Athe oat 28 conveys a forward movement to the upstanding arm 38 causing it to abut the screw 58 of the Vdepending arm 48 bringing about a forward movement of the armature 40., Obviously, the armature 40 is held by the depending magnet 56 in its rearmost position until the force of the magnetic attraction is overcome whereupon it is moved. forwardly and brought quickly into abutting engagement with the permanent magnet 54 effecting a snap action or quick closing of the valve seat I4 by the needle valve 32. Thus, the magnetic attraction of the magnet 54 holds the armature 40 in position there against maintaining the needle valve 32 in forward position for closing the valve seat I4.

As .the refrigerant evaporates in the evaporator 6, the liquid level is lowered and will finally reach level B. Under these conditions, as the liquid level is lowered due to the evaporating of the liquid, the upward pressure on the oat ball 28 and the arm 26 is reduced and the float tends to drop, but due to the magnetic force between the permanent magnet 54 and the armature 40, the float movement is stopped when the arm 38 comes in contact with the set screw of the arm 46 and remains in this position until the downward pressure on thefloat 28 is greater than the magnetic force between the permanent magnet 54 and the l When this downward pressure overcomes the magnetic force, the fl'at 28 and the arms 26 pull the armature 40 in a direction opposite to the magnetic attraction towards the depending L-shaped end 56 quickly bringing the needle valve 32 upon its pivotal support 30 to a fully open position. It will thus be seen that the float valve is now open and there is unrestricted passage for the liquid or vapor to enter the evaporator chamber 6 through the valve seat I4.

However, it is to be noted here that the pressure built up by the evaporation lof the liquid will be transmitted through the passage I8 in the nipple I4 to the chamber of the expansion valve and consequently against'the sylphon 10 which will hold the needle valve 88 of the expansion valve closed against its seat 66. As the pressure or temperature of the evaporator chamber rises to a predetermined setting of the condensing unit control mechanism, the condensing unit is started and pulls the gas from the chamber 6 through the tubngs l and I2 connected to the compressor, reducing the pressure in the evaporating chamber 6. As the. operation of the condensing unit continues, the pressure is reduced in the chamber 6 to a point where the pressure against the sylphon 'l0 is not great enough to hold the valve 68 closed against the seat 66, the needle valve 68 opens and allows pure liquid to enter from the tubing 56. As the liquid enters the chamber 63 of the expansion valve and the evaporator 6 it absorbs heat Aand evaporates, causing a rise in pressure against the sylphon 10, overcoming the spring tension of spring 18 and closing the needle valve 68 against its cooperating seat Se. This allows a constant pressure to be maintained in the chamber of the expansion valve through the passage I6 and the expansion chamber B. This constant pressure can be adjusted to any predetermined setting by the adjustment of the screw 80 and the spring 18. It can readily be seen that as long as the iioat valve is held at the level B the pressure in the evaporating chamber 6 is maintained constant by the expansion valve 60. As-the temperature of the evaporator l6 is reduced there will be only suiiicient heat to evaporate a certain portion of the liquid entering the chamber of the expansion valve and the liquid will be carried to the evaporator through the passage I6 raising the liquid above the level B which will increase the upward pressure on the oat 28 and arm 26, but due to the magnetic force between the armature 40' and the depending member 56, the oat is held in a downward position until the upward pressure of the float is suilicient to overcome the magnetic force between the armature 40 and the magnet 54 which will allow the armature to snap over against the magnet l through thecontacting of the upstanding arm 38 with the set screw 50 at the same time closing the needle valve 32 against its cooperating valve seat I8. At this time the level will be at A which is below the suction opening 68.

It is obvious that as the mechanism goes through a cycle of operations the float will snap open the needle valve 32 as the liquid level in the evaporator 6 is lowered to level B and as the liquid level is raised to level A the oat will snap shut the needle valve 32 against its'cooperating valve seat i8. The location of levels A and B is controlled by the adjustment of screws 56. Thus, it will be seen that `the-liquid level will always be between A and Blievels in the evaporator during a cycle of operation'.- 'Ihe operation previously described may occur one or more times during the operation of the condensing unit. As the nee-.- dle valve 32 closes, shutting off the passage of gas and liquid from the expansion valve 60, the pressure in the chamber 6 is reduced and because of the evaporation taking place during the cycle of operation sufficient heat is removed from the evaporator to a point where verylittle liquid is vaporized. This will allow thev condensing unit to reduce the pressure in chamber S to a predetermined point at which the condensing unit control mechanisrn is set to start the condensing unit orated pressure to maintain an approximate 20 evaporator. Assume that the evaporator is of sufficient size to maintain the nxture temperature by 16 hours operation out of the 24. When the condensing unit is placed into operation the oat l chamber and the entire evaporator contains no refrigerant, and shortly after the condensing unit is placed i'nto operation the pressure in the evaporator will be reduced 21A pounds. In the absence of liquid refrigerant inthe evaporator the snap action oat will be opened and when the pressurehas been reduced to approximately 21/2 pounds the expansion valve will open and feed a sufllcient amount of liquid into the evaporator to maintain a 21/2 pound pressure, providing the condensing unit is of suillcient capacity to handle the gas from this refrigerant when it is operated. In due time through the evaporation of the refrigerant the coil temperature will be reduced tol approximately 20, the temperature of the refrigerant at 21/pounds pressure. The capacity of the expansion valve must always be in excess of the refrigeration load so that when the coil reaches its temperature the refrigerant would gradually build up1in the coil until it reaches the predetermined level A in 'the float chamber, (Figure 1.) At this point the snap action mechanism cuts of! the liquid supply from the expansion valve. The condensing unit continues to operate until the low pressure control mechanism, which is usually set about 2 pounds lower than the setting ofthe valve, cuts oil? the supply of energy to the electric motor. The evaporator which is now approximately 20 in a 40 fixture continues to absorb heat ,which continues the evaporation of the liquid until the pressure is built up on the low side to a point where it will operate the high limit setting of the low pressure control which will start the condensing unit on Y another cycle. The snap action float may or may not have yet opened when the condensing unit starts. However, after a few minutes of operation suiilclent liquid may be drawn from the evaporator to drop. the liquid level before the pressure has reached the low pressure control setting. If

sufficient liquid is not drawn from the evaporator by the time it reaches the low pressure control setting a short cycle will result. If,`however, it does draw suicient liquid from the evaporator so that the float valve opens a regular cycle will be the result.

Figures 6, 7, and 8 are curves showing one cycle by a low pressure switch set to start the condensing machine at ten pounds pressure. The cut out point of the switch varies with the different type of control, as the desired fixed temperature is reached ,with a shorter cycle with the float and expansion valve combination because of the higher average back pressure. These charts are typical and are shown to illustrate the eillciency of the combination of the float and expansion valve system of the present invention over the two conventional types now in use.

Referring now to Figures 2 and 3, it-will be seen that there is shown a modified form of the invention which performs in combination with the expansion valve substantially the same result as the previously'described snap action switch, which utilizes a magnet for obtaining the snap action effect. In this form of the invention, as illustrated in Figures 2 and 3, the expansion valve is connected to the closure plate 8 as previously described, the header being provided with the pro- `jecting nipple I4 having on the inner end thereof a valve seat I8. A cap |08 is screw-threaded on the nipple |4 which has a laterally extending arm |08 to which there is secured by means of a screw bolt ||0 a support I I2. As clearly illustrated in Figure 3, the arm |08 is bifurcated at its free end and has extending therethrough a pin I I4 on which there is pivotally mounted the upstanding support II8. To the free end of the support ||8 there is pivotally supported a needle valve |20 slidable in the bore in the cap |08 and cooperating with its associated valve seat I8. Obviously,

As shown in Figure 2, the support ||2 at its free end is provided on each side thereof adjacent the end with upstanding ears |22 carrying the transversely disposed pin |24 on which there is pivotally mounted the U-shaped member |28. It l will be observed that the arms |28 of the U-shaped member are provided with set screws |80 and have disposed therebetween a transversely extending pin |82 disposed in thelarms |20. Obviously, upon upward and downward movement of the arms |20, one or the other of the free ends of the set screws |80 are brought into contacting engagement therewith to the end that the U-shaped member |28 is moved about its pivot |24. Extending laterally from the bight portion of the U-shaped member |28'is an integral a'rm |40 havingfits free end sharpened toza substantially knife edge as at |42.

As clearly illustrated,A to the outer-side of the pivotal upstanding support ||8 there is secured an L-shaped arm |44, the depending portion |48 thereof being bent outwardly providing a. laterally extending arm` |48, the free end of which is formed with a knife edge. Between the knife edges of the arms |48 and |48 as shown there is arranged a substantially horseshoe-shaped spring |80. 1

In operation it will be apparent that as the arm |20 is moved in a vertical plane by the rise and fall of the refrigerant, the pin |82 will contact one of the adjustment screws |80 and rotate the U-shaped member |28 around its' -pivot causing the knife edge of the arm |40 to This will cause a pressure due to the expanding of the spring against the member |48 which will move armA |44 land-'support ||8 forwardly causing the needle valve to move forward and close against its seat I8. With the needle valve I 20 in seated position, the passage I8 in the nipple is closed. Whenlthe level of the liquid in the evaporator lowers the float on the free end of the arm |20 (not shown), the arm |28 will pivot about itspin |.I4 lowering the pin |82 bringing it into contacting engagement with the lower adjustment screw |88 transmitting pressure to the arm |40 rotating the arm |40 in a counterclockwise direction.' This will raise the knife edge on the arm |40 until it passes the center line of pinsv||8 and |24 where it will releasethe spring pressure of spring |80 in a downward direction against the knife edge of the arm |48 which will rotate the support'||8 in a counterclockwise direction pulling the needle |20 away from its seat I8 opening the passage I8. Obviously, the movement of arm |20 and arm |40 will not be transmitted to the needle valve |20 until the knife edge of the arm |40 goes past the center line of the two knife edges andthe center line of pins ||8 and |24 at which point the needle valve |20 snaps open or closes in accordance with the direction of movement of arm |20. Clearly, this snap action type of float valve when-employed and combined with an expansion valve as previously described with respect to the magnetic type illustrated and described in Figure 1 functions in the same manner and it is not thought necessary to again describe the cycle of operation.

Referring now to Figures 4 and 5, it will be .seen that there is shown a further modified form of the invention which utilizes an electrically controlled valve in combination with an expansion valve which is operated through the medium of a float, the valve being actuated in a snap action manner.

As illustrated, the expansion valve |88 which is of the usual type employed such as described with respect to Figure 1, is connected to the header |82 -of the evaporator (not shown) by means of the connection |84. To the nipple of the header |82 there is screw-threaded a cap |88 having a laterally extending arm |88 thereon, to the free end of which there is pivotally mounted the L-shaped arm |80 carrying the float ball |82.' To the` free end of the upstanding arm |84 there is pivotally mounted a mercury bulb |88 having space contact members |88 therein adjacent one end thereof. As clearly shown, these contact members project inwardly in the bulb and upon rotation of the bulb in the proper direction the contact members |88 'are adapted to be bridged by the mercury |10 therein for closing the same. Rotation of the bulb is effected by the depending arm |12 which is movable between the adjustment screws |14 arranged in projecting ears |18 on. the arm |84. It will thus be seen that the movement of the bulb may be controlledthrough the medium of the adjustment screws |14 which limit the travel of the arm |12. Obviously, upon an upward or downward movement of the arm |80 through the medium of the float |82 which in the usual manner is controlled by the refrigerant the mercury bulb is rotated in one direction or the other to effect through the medium of the mercury an opening or a bridging of the contacts |88. The header |82 is provided with spaced bores therein through which extend the binding posts |18 which are inservice in refrigerating systems of the compressor,

sulated therefrom and to which the contacts |68 are connected by the conductors |80. The liquid refrigerant supply from the condensing unit is supplied by the conduit |82 which is connected to the expansion valve |50. Between supply conduit |82 and expansion valve |50 for controlling the supply of refrigerant to the expansion valve there is provided a solenoid actuated valve |84. As shown the solenoid valve is provided with a needle valve in the form of an armature |86 which cooperates with its valve seat |88. The needle valve |86 is normally maintained in its closed position through the medium of the spring |90 and is moved to open position upon energization of the solenoid |92. The winding of the solenoid is connectedto contacts |68 and a source of electrical supply by conductors |94.

Obviously, as the arm |60 rises, themercury bulb is rotated tilting the mercury in a forward direction allowing the mercury to break contact with the contacts |68 de'energizing the winding of the solenoid permitting o f the closing of the needle valve against its valve seat and `stopping the ow of the refrigerant to the expansionvalve |50. When the liquid level in the evaporator lowers and the float |62 lowers the arm |60 the mercury in the bulb moves in a counter-clockwise direction allowing the mercury to bridge and close the contacts |68 energizing the winding of the solenoid raising or opening the needle valve permitting of the refrigerant to pass into the expansion valve I5. Thus, the combined action of this type of valves withgthe expansion valve is the same as previously described more in detail with respect to the valve shown in Figure l, and it is not thought necessary again to describe the complete cycle of operation thereof.

It will thus be seen from the foregoing that-V there is provided a combined snap action float valve and expansion valve which insures a flooded condition of the evaporator at all times and insures the feeding of the refrigerant to the evaporator at a constant suction pressure at a predetermined setting during the time the oat valve is open, thereby increasing the efficiency of the .evaporator and the condensing unit 'and greatly reducing the necessity of adjustment and evaporator type refrigeration.

While there is shown for the purpose of illustration preferred embodiments of the invention,

it is to be understood that they are capable of various changes and rnodications without departing Vfrom the spirit and scope thereof, and it lis intended therefore that only such limitations shall be imposed thereon as are indicated in the refrigerant supply to said chamber, a snap action opening and closing float valve arranged to control the flow from said supply line and a pressure control valve in said supply line.

2. In a refrigerating system including a refrigerant evaporating chamber, a source of refrigerant. supply, a conduit communicating said refrigerant supply to said chamber, a snap action opening and closing valve arranged to control the ow from said conduit, said valve being controlled by the refrigerant level in said chamber, and a pressure controlled valve in said conduit.

3. In a refrigerating system including a refrigerant evaporating chamber, a source of refrigerant supply, a supply line connecting said refrigerant supply to said chamber, a snap action open-` ing and closing valve arranged to control :the

y and a pressure controlled valve actuated by'the pressure of therefrigerant supply and the pressure in the evaporatingchamber through the snap action float yalve.

5. In a refrigerating system including a refrigerant evaporating chamber, a source of refrigerant supply, a supply line communicating said refrigerant supply to said chamber, means' for controlling the refrigerant in said chamber from said refrigerant supply comprising in combination a snap action opening and closing valve actuated by the refrigerant level in said chamber, and a pressure control valve in said supply line.

6. In a refrigerating system Vincluding a refrigerant evaporating chamber, a source of refrigerant supply, a supply line' communicating said refrigerant source of supply to said chamber, means for controlling the refrigerant in said chamber comprising in combination, a snap action opening and closing valve actuated by the refrigerant level in said chamber, and a pressure control valve in said supply line between the refrigerant source of supply and the snap action valve controlled by the pressure from the refrigerant source of supply and the pressure in the evaporating chamber through the snap action opening and closing valve. Y

7. In a refrigerating system including a refrigerant evaporating chamber and a -source of refrigerant supply, a supply line for conveying said refrigerant to said chamber, a float actuated valve arranged to control the ow from said supply line, said valve being controlled by the refrigerant level in said chamber, means for effecting a snap action opening and closingv of said valve, and a pressure control valve in saidsupply line.

8. In a refrigerating system including a refrigerant evaporating chamber and a source of refrigerant supply, a supply line for conveying said refrigerant to said chamber, a magnetically actuated snap action opening and closing float valve arranged to control the ow from said supply line, said valve being controlled' by the refrigerant level in said chamber, and a pressure control valve in said supply line.

9. In a refrigerating system including a refrigerant evaporating chamber and a source of refrigerant supply, a supply line for conveying said refrigerant to said chamber, a spring actuated snap action opening and closing float valve arranged to control the ilow from said supply line, said valve being controlled by the liquid level in lsaid evaporating chamber, anda pressure consaid refrigerant to said chamber. means for controlling the refrigerant from said supply lto said chamber comprislng'in combination, an adjustable snap action opening and closing oat valve arranged to control the ilowfrom said supply line, saidvalve being controlled by the level of the refrigerant in said chamber, and an adjust'- able pressure controlled expansion valve in said supply line.

11. In a compressor-condenser-expander reirigerating system, control means for the iiow of the refrigerant comprising a low side float controlled valve, in series with a pressure control valve responsive to evaporator pressure.

12.`In4 a compressor-condenser-expander refrigerating system, control means including means responsive to the liquid level in the evaporator in series with pressure controlled means responsive to evaporator pressure.

13. In a compressor-condensarsexpander refrigerating system, control means including means responsive to the quantity of liquid in the evaporator in series with pressure controlled means responsive to evaporator pressure.

PAUL RAYMOND.