US2581956A

US2581956A - Refrigeration control device

Info

Publication number: US2581956A
Application number: US31591A
Authority: US
Inventors: Frederick M Jones
Original assignee: U S THERMO CONTROL CO
Current assignee: U S THERMO CONTROL CO
Priority date: 1948-06-07
Filing date: 1948-06-07
Publication date: 1952-01-08
Anticipated expiration: 1969-01-08

Description

F. M. JONES REFRIGERATION CONTROL DEVICE Jan. 8, 1952 2 SHEETS-SHEET 1 Filed June '7, 1948 mmvrox. Fkevemm M. Aowzs 3% florne Jan. 8, 1952 JONES 2,581,956

REFRIGERATION CONTROL DEVICE Filed June 7, 1948 2 Sl-XEETSSl-IEET 2 INVENTOR.

Feeoemcx- M Jones Patented Jan. 8, 1952 REFRIGERATION CONTROL DEVICE Frederick M. Jones, Minneapolis, Minn., asslgnor to The U. S. Thermo Control 00., Minneapolis, Minn a corporation of Minnesota Application June 7, 1948, Serial No. 31,591

14 Claims.

My invention relates to improvements in a refrigeration control device for controlling the flow of a refrigerant fluid. In particular it relates to a fluid flow control device which is used .in a refrigeration system to limit the flow of refrigerant fluid from an evaporator to a compressor when the fluid in the evaporator is under considerable pressure representing a volume of fluid which is in excess of the normal capacity of the compressor.

In refrigeration systems of the compressor condenser-evaporator type, conditions may and frequently do arise, when the amount of refrigerant in the form of gas. is present in the evaporator in a quantity which is beyond the normal capacity of the compressor to satisfactorily remove and compress. This condition can arise when the refrigeration unit has been inactive for a considerable period of time and conditions surrounding the evaporator are static, and then rapidly changed, or when the evaporator is subjected to conditions where a very high rate of heat exchange is occurring. In either instance,

an excessive load is placed on the compressor and also on the prime mover, such as the motor or engine which is provided to drive the compressor.

In most instances, refrigeration units are constructed with the prime mover being connected ,to the compressor by a direct drive, such as a driven shaft rigidly coupled between the prime mover and the compressor, or by an indirect connection which includes pulleys and belts. Discounting as negligible the effect of slippage when an indirect drive is used, the full load of the compressor is placed directly on the driving member, and ordinarily there is no convenient way of disconnecting the load prior to starting the prime mover. Thus, when the unit has been inactive for some time, and where there is likelihood of a very high pressure existing in the evaporator because of the high rate of .heat exchange, a problem arises in starting the prime mover because of its direct connection to the compressor and because the compressor is thus required to start under heavy overloaded conditions. In the instance of an internal combustion engine used as the prime mover, the starting motor or other mechanism used to initiate operation of the engine is relatively weak and is not ordinarily intended to turn over the engine when the latter in addition to being connected to the compressor, which constitutes a considerable load, must also move the compressor against the resistance of a heavy overload. Thus in one instance the pressure of gases present in the evaporator may prevent the starting of the engine, or at least seriously overtax its starting mechanism. In a second instance, when the prime mover is an electric motor, problems of another form concerning starting can arise. If

the motor is of the type which is provided with a starting winding and a running winding, the initial overload can be so great as to prevent the motor from reaching sufficient speed to shift from the one winding to the other. When the motor construction is of a type which is provided with a single winding, the overload can be so great as to cause destruction of fuses positioned in the electrical lines between the source of current and the motor.

The foregoing discussion illustrates the situation where the temperature in the space surrounding the evaporator is relatively high and the problem is in starting the unit. Still another situation arises when the unit has been in operation and is suddenly overtaxed. An example of this situation is when a space used for storing or transporting fresh vegetables is quickly loaded with produce from the field, which material is still radiating the heat of summer temperatures. This is a condition which constantly confronts the refrigerated transport industry and is serious enough to cause the prime mover employed for driving the compressor to burn out or otherwise to become seriously injured.

Nor is the problem solely confined to either the starting operation or to a mere overtaxing of the prime mover for driving the compressor, but rather it is also concerned with the application or use of the refrigeration unit. Generally speaking, refrigeration units are utilized in one of three diiferent ways: for deep freeze purposes, where extremely low temperatures must be maintained within a space or enclosure; for moderate refrigeration needs, where the required temperature is above the freezing point of water; and for air-conditioning purposes, where the required temperature is relatively high but where the rate of heat exchange is also high. Ordinarily for each of these specific uses a different type of compressor construction is used, since one which would be suitable for the extremely low temperature of a deep freeze unit is totally unsuited for the relatively high temperature requiied in an air-conditioning unit, where the rate of heat exchange is very high. As a result, the manufacturers of compressors have been forced to go to the additional expense of providing a different compressor displacement for each one of the three general uses set forth above, even though the total amount of refrigeration in each instance is approximately the same.

The problem of finding a satisfactory manner of handling the overload pressure to the compressor has long been recognized by the industry and various forms of fluid pressure control devices have resulted. I am aware of some of these devices, but in my opinion they do not furnish a satisfactory solution to the problem, and particularly to the phase of preventing an overload 3 on the prime mover during a starting operation. Furthermore, it has been my observation that where pressure responsive valves have been usedthey are either incapable of completely closing, or else they have a tendency to stick, or they are relatively complex in nature and are, there'- fore, expensive to obtain.

In the present invention, a control device provided which is adapted to be connected besystem in tween the evaporator and thecompressor for controlling the flow of refrigerant fluid insuch a manner as to prevent an excessive load Ironsstalling or injuring the starting mechanism of the prime mover, and which is also capable-"of-* preventing an overload condition from injuring the compressor or the prime mover while the unit is in active operation.

The present device includes what I believe to be a novel form of valve mechanism that is capable of completely shutting off the flow of fluid through the device; The valve includes a piston which is mounted within a cylinder and utilizes the high fluid pressure to aid in keeping the valve closed. A passage is formed between the cylinder and a point beyond the outlet side of the valve for relieving the pressure on the piston thereby maintaining a pneumatic balance on opposite sides of the valve so as to render it subject to operation independent of the inlet pressure however great that may be. A second valve is positioned in the aforementioned passage for controlling the flow of fluid through the passage. This second valve is controlled 'by the prime mover, or a condition associated with the prime mover, so as to prevent overloading the prime mover either when the same is being started or at any time when it is excessively overloaded.

An object of the invention is to provide a fluid flow control device for use in refrigeration apparatus to prevent overloading a compressor when the load is otherwise in excess of the normal capacity of the compressor.

Another object is to provide a pressure responsive control device which includes a valve mechanism that is capable of closing tightly with respect to its seat, but which is capable of being maintained in pneumatic balance .by a substantially common fluid pressure on either side of the valve seat.

Another object is to provide a fluid flow con trol device for use with refrigeration apparatus having a first portion controlled by fluid pressure and another portion controlled by a part of the apparatus with which the control device is associated.

A further object is to provide a control device for use in a refrigeration system which includes a pressure responsive valve mechanism, a by-pass connecting remote portions of the valve mechanism so as to maintain the valve mechanism in pneumatic balance and responsive to a pressure condition existing on one'side of the valve seat, together with a valve in the bypass which is controlled by a condition associated with the prime mover used to drive the refrigerant compressor.

A further object is to provide in combination with a refrigeration system that includes a compressor and an engine-for driving the same, a control device for completely shutting off the flow of fluid to the compressor when for any abnormal reason such as overheating, the engine begins to labor, thereby permitting the engine to regainnormal operating conditions.

Other and further objects and advantages may become apparent from the following description and. claims, and in the appended drawings in which:

5 big. 1 is a vertical section in side elevation of arefrigeration control device forming the present invention and shown as being operatively joined to a governor of a prime mover;

lrig. 2 is a schematic view of a refrigeration which the present invention is incorporated; and;

1 Fi 3 is a schematic view of another type of prime mover that may be used in the refrigeration system shown in Fig. 2.

Referring now to the several views of. the drawing,...the invention will be described in detail. Referring. first to Fig. 1, general reference numeral l0 indicates a refrigeration control device in the form of a casing I2 having removable upper and lower portions 14 and [6 that are secured to the body of easing l2 by conventional fastening means l8. Casing I2 is provided with a threaded inlet 20 and outlet 22 for connection to conduits extending to an evaporator and a 25 compressor of a refrigeration system as shown in Fig. 2. Within its interior, casing I2 is providezi with a partition 24 that extends horizontally across the interior of the casing to separate the casing into an inlet chamber 26 and an 30 outlet chamber 28. Partition 24 is provided with an enlarged aperture 30 which forms a valve passage between the inlet and outlet chambers.

Within the interior of the inlet chamber 25 and depending from the upper surface I4 is a wall 32 which is continuous in nature and defines a cylindrical chamber 34. Wall 32 extends in the direction of partition 24, but is separated therefrom for a short distance to form a pas sage 33 between inlet chamber 26 and the aperture 30. Extending through one portion of wall 32 between the inlet chamber 26 and the cylindrical chamber 34 is a passage 36. Extending through another portion of wall 32 between cylin drical chamber 34 and an exterior surface of the control device is a second passage 38. As shown in Fig. l, the

passages

36 and 38 are formed integral with the removable upper portion l4 of casing l2, but where desired, they could, if necessary, take the form of independent conduits exterior to the casing, as their only purpose is to provide fluid connections between the various portions of the casing as shown. A feature of some importance which will be evident hereinafter is the fact that passage 38 has a substantially larger fluid flow capacity than passage 36. Mounted within the interior of easing I2 is a valve structure'indicated by general reference numeral 46 and consisting of a piston 4| which is slidably mounted Within the cylindrical chamber 34 but separated from wall 32 by a relatively small distance which may be in the nature of .005 inch, and, therefore, does not forman absolutely fluid-tight seal with the interior of wall 32. Piston 4| is a hollow cup-shaped member whose interior and particularly the bottom wall thereof is referred to hereinafter as a piston head 42. Piston 4| is slightly larger in diameter than the opening 30 of partition 24 and has a circular recess 43 formed on its lower surface with an annular off-set ledge 44 at its periphery. A circular disk 45 having an annular flange 46 fits within recess 43 and is secured against the piston head 42 by screws 41. An annular rubber gasket 48, which is cylindrical in cross-section, fits within the-space between the ledge 44 and flange 46 and is securely heldin place by disk 45. When so held, a portion of gasket 48 protrudes below the surface of the piston and forms a resilient surface which engages the surface of partition 24 and around the aperture 80 and forms what is hereinafter referred to as a valve seat. Thus piston 4| actually serves as a valve member, and its construction in the form of a piston is for other purposes to be disclosed hereinafter.

Extending downwardly from the lower surface of disk 45 is a rod 50 having a flange 5| that is secured to the top of a resilient diaphragm, here shown as a bellows 52. About its lower edge 54 bellows 52 is rigidly secured to the bottom plate I6 of the casing. In order that the bellows may be subjected to atmospheric pressure within its interior, a small aperture 56 extends through wall I6 into the interior of the bellows. Within the interior of bellows 52 is a compression spring 58 which at one end contacts the upper interior surface of bellows 52, and at its lower end contacts a washer 60 that surrounds a plug 62, which in turn extends through lower wall I6 of the casing.

' Shown mounted on one side of casing I2 is an auxiliary valve structure indicated by general reference numeral 65, and consisting of a casing 64 which is connected by a first conduit 66 to passage 88, and by a second conduit 68 to a passage I0 within the threaded outlet 22 of casing I2 and in fluid communication with the outlet chamber 28. Within its interior, casing 64 is provided with a partition I2 in which is formed a valve seat 14. A movable valve I6 is adapted to cooperate with valve seat 14 and is held in a normally closed position by a coil spring 18 that surrounds an armature or core 80 formed of magnetizable material. An induction coil 82 is positioned in proper relationship with core 80 and forms with the core a solenoid operator for moving valve I6 away from its seat I4 when the coil 82 is energized.

Indicated by general reference numeral 84 is a speed control governor having a casing 86 within which extends one end of a shaft 88, that is supported in a bearing 90. Within casing 86 and secured to shaft 90 is a rotatable member 9|.

Secured to member 8I by pivots 92, 94, are a pair of

inertia weights

86, 98 that have L-shaped extensions I00, I02. The extensions I00, I02 engage one side of a collar I04 that is slidably mounted on shaft 88. A lever I06 which is pivoted at I88 has one end H0 in contact with collar I04 and another end II2 connected to a rod H4 which extends to the throttle of an internal combustion engine, not shown, for controlling the flow of fuel to the engine A tension spring M8 is connected between one portion of lever I06 and a portion of casing 86 to bias the lever in the inactive position shown, to resist movement of collar I04 by the

weights

86, 88 until the shaft 88 is rotating at some point between approximately 80 and 100 per cent of the maximum rated speed of the engine to which shaft 88 is connected. The portions of governor 84 thus far described are conventional.

Suitably mounted with respect to governor 84, and here shown as being supported on bearing 80 is a switch II8 containing a stationary switch blade I28 on which is mounted a contact I2I, and a resilient blade I22 that supports a movable contact I23. Blade I22 is actuated by a pin I24 held in contact with a portion of lever I06 by the ill resilience of the blade I22. As shown. contact 76 I88 is separated from contact HI and this condition will prevail as long as shaft 88 is stationary or is rotating at less than approximately 80 per cent of its maximum rated speed.

Extending from a source of power I20 is a conductor I28 that joins the resilient blade I22. A second conductor I80 extends from the source of. power I26 to one end of the induction coil A third conductor I82 Joins the other end of coil 82 with the stationary switch blade I28.

Referring now to Fig. 2, the control device I0 and the governor 84 are shown in their respective relationships, in a diagrammatic fashion with a refrigeration system. The system includes a prime mover, here schematically represented as an internal combustion engine I84, on which the governor 84 is mounted. Suitably connected to engine I34 by a drive shaft I85 is a compressor I86. The governor 84 is driven by a belt I81 which is in turn driven by shaft I85.

A conduit I88 extends from the high pressure side of compressor I86 to a condenser I40. Condenser I40 is connected to a receiver I42, that is in turn connected through an expansion valve diagrammatically shown at I44 to an evaporator I46. A short conduit I48 extends between the outlet connection 22 of the control device I0 and the compressor I36. The operation of the device shown in Fig. 1 will now be explained in conjunction with the refrigeration system shown in Fig. 2. Assuming a first condition in which the refrigeration unit has been inactive for some time and the temperature of the air ambient to evaporator I46 is static. Thiscondition is then suddenly unbalanced by introducing into the enclosed space surrounding the evaporator a source of considerable radiant heat, which might be a large quantity of produce that has been subjected to summer heat, or a large number of people entering an air conditioned space. As soon as the risin temperature within the space affects the evaporator, expansion valve I44 will open and thereafter other control means, not shown nor forming a part of this invention, will initiate operation of engine I34. However, the amount of refrigerant liquid which has already been converted into gas in the evaporator will, even in this short time, be considerable and will create considerable pressure within the evaporator. If this pressure is permitted to exert itself a ainst the compressor it would constitute a heavy load on the compressor and on the starting mechanism used to initiate operation of engine I 34. The device I0 is provided to control this excessive pressure.

Plug 62 is set to create a pressure on spring 58 which represents a volume of fluid that is equal to the rated capacity of the compressor and this setting is of course adjustable. Valve 40 will always initially be in a normally closed position with the piston 4i and gasket 88 against partition 28. Valve 16 is also closed with respect to its seat I4. Under these conditions gas can enter the inlet 20 passing into chamber 28 and through passage 36 into the cylindrical chamber 84 or through the opening 83, and thence between the wall 82 and piston 4I into chamber 34. However, because valve I6 is closed, the gas cannot leave chamber 34 beyond entering passage 38. And it, therefore, exerts its full pressure against the piston head 42 to hold the valve completely closed.

While the engine I34 is being started it will commence to drive the compressor I86 and the through conduit I48 from the interior of the outlet chamber 26. When this occurs, or within a moment thereafter, the compressor will. tend to fluid in the inlet chamber 26 is very great, nothing will' happen because communication with the compressor is completely closed. Thereafter and in a very short interval of time engine I84 will easily approach its maximum rated speed because of the absence of any load on the compressor, and governor 84 now comes into operation. Depending on .the rated tension of spring II6, collar I04 will be held secure against lugs I and I02, even though the

weights

86 and 88 are rotating in unison with member 8| and are attempting to move outwardly on their pivots 82. 94. When, however, the centrifugal force of

weights

86, 98 exceeds the tension of spring II6, thereby indicating that shaft 88 is rotating at a speed which is at least 80 per cent of its rated speed, they will rapidly rotate on their

pivots

82, 84, driving collar I04 to the left, as shown in Fig. l, and causing lever I06 to rotate on its pivot I08. As the lever I06 moves away from the position shown in the drawing, pin I24 will follow the lever and permit the movable contact I23 to engage the flxed contact I2I, When this occurs, a circuit to coil 82 will be established which may be traced as follows: from the source of power I26, through conductor I28, switch blade I22, movable contact I23, fixed contact I2I, switch blade I20, conductor I32 to the induction coil 82, and thence back to the source of power I26 through conductor I30. When the induction coil 82 is energized, core 80 is moved upwardly against the resilience of spring 18 to move valve I6 to an open position with respect to its seat 14.

When the valve I4 is opened, fluid present in the inlet chamber26 can pass through passage 36 into the cylindrical chamber 34, through passage 38 and connection 66 to the casing 64, through the seat I4 and connection 68 to the outlet connection 22 of the control device. The flow of gas through the connections described will not be suificient to satisfy the needs of the compressor, but will be sufllcient to maintain a relatively low pressure in cylindrical chamber 34, which pressure is substantially equal to the pressure in chamber 28. Under these conditions piston H is now in pneumatic balance with respect to chambers 28 and 34, and bellows 52 aided by spring 58 can move the piston 4I away from the valve seat because of the equal pressures in chambers 28 and 34 and because this pressure would by now be less than the pressure on spring 58. When this occurs, the fluid refrigerant in chamber 26 can pass through the opening 33 and aperture 30 and into chamber 26 and thence through outlet 22 to the compressor. The extent to which the piston is moved away from its valve seat is dependent entirely upon the pressure of gases in chamber 28. Bellows 52 constitutes a differential pressure diaphragm between atmospheric pressure on its interior, and the pressure in chamber 28 on its exterior, and will tend to collapse as the pressure in chamber 28 increases. Since the bellows 52 is connected to the piston 4|, it will tend to move the piston downwardly against its seat; however, spring 58 is within the bellows and will. to the extent that it is placed under pressure, resist this movement.

' Thus an increase of pressure in chamber 28 will tend to close the valve, and a decrease of pressure in chamber 28 will tend to open the valve.

In maintaining the balanced condition on opposite sides of the valve structure 40, the construction of the piston and the cylinder within which it moves, as well as the dimensions of the passages connected therewith are important. Piston H was previously described as being of diameter which is slightly less than the diameter of wall 82. This not only permits the piston to freely move within the cylinder wall, but it also oflers an alternative passage by which the gas within chamber 26 can enter chamber 34. Ordinarily both forms of permitting entry of the gas would not be used, as the total quantity of gas entering chamber 24 must be substantially less than the quantity of gas which can be removed therefrom through passage 38. This is critical because in order to maintain the valve 40 in pneumatic balance when valve 14 is open, it is necessary that the pressure in chamber 34 be substantially the same as the pressure in chamber 28. By forming the valve as a piston and enclosing it within the cylinder 34 it is possible to regulate the flow of fluid without regard to the extent to which the pressure has developed in the evaporator I46.

The foregoing discussion has largely applied to the starting operation, but a second condition can arise even when the apparatus is in actual operation. The second condition will arise when the radiant heat load of whatever is brought into the controlled space exceeds the heat exchange capacity of the evaporator, or at least taxes it to its limit. This condition will cause the expansion valve I44 to remain open. The rapid conversion of refrigerant from the liquid to the gaseous stage will again provide a higher fluid pressure than the compressor can suitably handle.

Instead of permitting the prime mover to burn itself out on the overload, the control device will act to restrict the flow of fluid to the compressor to an amount which is within the normal capacitlyi of the unit, thus saving costly repairs to the Reference was previously made to the fact that the control device I0 is subject to adjustment by means of changing the pressure on spring 58. It was also mentioned that the control device may be used with one type of compressor in any one of three different systems. As an example, when the compressor is used with a deep freeze unit the pressure on spring 58 would be relatively light so as to enable the compressor to maintain a relatively low pressure in the evaporator. It is within the conception of my invention to render spring 58 completely inactive and utilize the atmosphere entering passage 56 to form the pressure means for opening thevalve. The control device would, in the manner previously explained, still be capable of preventing an overload. Likewise, in the event the compressor was used with an air conditioning unit, the pressure on spring 58 would be increased, but never to the extent of permitting passage of a volume of fluid which is in excess of the safe capacity of the compressor.

Still another condition of considerable importance is when the system is used on a transport vehicle or when for some reason unusual conditions arise and cannot be quickly detected. The conditions to which I refer might arise if the engine overheats through lack or'suflicient ventilation, or because the engine developed carbon deposits. When either of these conditions occurred, the engine would labor and might easily destroy itself, but if freed of its load, it could soon correct the condition. When, therefore, the engine slows down the governor will open the switch which de-energizes the auxiliary valve that in turn will cause the main valve to close, thereby completely stopping refrigeration and relieving the engine of the load beyond driving an inactive compressor. When the condition has corrected itself as by way of cooling the engine with its cooling blower, or by burning out the carbon deposits, the engine will again resume its normal operating condition and refrigeration may be automatically started again.

Referring now to Fig. 3 is shown an alternative form of prime mover for driving the compressor, together with an alternative structure for replacing the governor 84 shown and described in connection with Figs. 1 and 2. Reference numeral I50 indicates an electric motor having a driven shaft I52 which is adapted for connection to the compressor I36. Shown at the left of the motor is a relay I53 consisting of an induction coil I54 having a plurality of taps I56, I58 and I60 connected thereto. Extending within the interior of induction coil I 54 is a core or armature I62 which at its upper end is connected to a movable switch blade I64 that is pivotally mounted at I66 and carries on one end a contact I68 that is adapted to engage a fixed contact I10. On the left hand side of the pivot I66, blade I64 is secured to a spring I12, which spring is anchored at I14. Also shown in Fig. 3 is the auxiliary valve 65 which is substantially the same in all extent as the auxiliary valve 65 shown in Fig. 1.

The electrical connections in Fig. 3 consist of a pair of conductors I16 and I 18 which extend from a source of power, not shown, to a pair of switch blades I80 and I82 thatare adapted to simultaneously engage contacts I 84, I86. A conductor I88 extends from contact I86 to one end of the induction coil 82. A conductor I80 extends from contact I84 to one end of induction coil I54. From the other end of induction coil I54, a conductor I82 extends to one pole of motor I50. -A conductor I84 extends from the other pole of motor I50 to conductor I88. A conductor I86 extends from conductor I80 to contact I10, and a conductor I88 extends from contact I68 to the other end of coil 82.

The operation of the structure in Fig. 3 will be explained with the understanding that the contact I68 in engagement with contact I 10. The whole purpose of the relay structure I53 is to maintain contacts I68. I10 separated until the motor approaches its full operating speed without regard to the length of time required for this to take place. Relay I53 serves the same purpose as governor 84, both as to the starting condition and also as to any abnormal condition. In the one instance contacts I 68, I10 are separated until the motor approaches its normal operating condition, but if any condition causes the motor to labor, the two contacts would again be separated so as to unload the compressor.

When contacts I68, I 10 are closed, a circuit is completed to coil 82, which may be traced as follows: from the source of power, not shown, through conductor I16, switch blade I80, contact I84, conductor I80. conductor I86, contacts I10, I68, conductor I88, coil 82, conductor I88, contact I86, switch blade I82, and conductor I18 back to the source of power. In passing, it should be mentioned that contacts I68, I10 constitute a normally closed switch and, therefore, when switches I80, I82 are initially closed, power will flow to coil 82 for an instant before coil I54 causes a separation of contacts I68, I10. The effect of the initial energization of coil 82 is negligible and of no consequence in the operation of the system.

The several taps I56, I 58, I on the induction coil I54 serve as alternative connectors for one end of conductor I82. They may be used either as an adjustment for obtaining a proper balance with sprin I12, or for connecting the relay to motors of increasing capacity. Thus for a one H. P. motor tap I56 may be used, whereas taps I58 and I60 may be used on motors of three and five H. P. capacity, as it is well known that inductance is a relationship between the number of turns in the coil and the number of amperes of energy passing through the coil.

The principal advantage of the present invention resides in a simplified manner of controlling the flow of fluid refrigerant in a refrigeration system between an evaporator and a compressor and preventing an excessive pressure of the fluid from injuring the compressor or its driving mechanism.

Another advantage is in providing a control device having a portion controlled by the prime mover which drives the compressor so as to prevent the flow of fluid to the compressor until the prime mover approaches its full operating electric motor I50 is substituted in place of engine I34 as the prime mover used to drive compressor I36. When the switches I80, I82 are closed with respect to contacts I84, I 86, power will flow from the source of power, not shown through conductor I16, switch blade I88, contact I84, conductor I80. coil I54, conductor I92, motor I50, conductor I84, conductor I88, contact I 86, switch blade I 82 and conductor I18, back to the source of power. Even though there is a relatively light load or no load at allon the motor, there will be a surge of current through the induction coil which will create suflicient induction to pull the armature I62 downwardly against the resilience of spring I 12. However, when the motor approaches its full speed, the current flow is diminished and the force of spring I12 will overcome the inductive pull on the armature and will permit the switch blade I64 to move back to the position shown ,.with

speed, and which is also operable to unload the compressor in the event that any abnormal condition would arise to overload the prime mover.

Another advantage resides in providing a con trol device for controlling the flow of refrigerant fluid in which a single type of compressor may be applied in a plurality of systems, each of which has a widely differing characteristic heretofore requiring the use of a modified form of compressor for each application.

My invention is defined in the terms of the appended claims.

I claim:

1. A refrigeration control device adapted for connection between a fluid evaporator and a compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, at pressure responsive valve within the casing between the inlet and the outlet, a chamber formed within said casing and Surrounding a portion of the valve, 9. fluid communication extending between the inlet and the interior of said chamber, a second fluid communication extending between the interior of the chamber and the outlet, a two-position valve in said second communication, a prime mover for driving said compressor, said prime mover having a first range of operating speeds representing abnormal operation and a second range of speeds representing normal operation, and control means operatively connected between said prime mover and said two-po si%n valve for moving the latter to one of its positions when the operating speeds of said prime mover change from one range to the other. Y

2. A refrigeration control device adapted for connection between a fluid evaporator and a compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a pressure responsive valve within the casing between the inlet and the outlet, a chamber formed within said casing and surrounding a portion of the valve, a fluid communication extending between the inlet and the interior of said chamber, a second fluid communication extending between the interior of thechamber and the outlet, a two-position valve in said second communication, a prime mover for driving said compressor, said prime mover having a first range of operating speeds representing abnormal operation and a second range of speeds representing normal operation, a speed responsive governor operatively connected to said prime mover and being movable between two positions I when the operating speeds of the prime mover change from one range to the other, and control means operatively connected between said governor and said two-position valve for moving the latter to one of its positions when the governor is moved to one of its positions.

3. A refrigeration control device adapted for connection between a fluid evaporator and a compressor for controlling the flow of fluid to the compressor, comprising a casing having an'inlet and an outlet, a pressure responsive valve within the casing between the inlet and the outlet, a chamber formed within said casing and surrounding a portion of the valve, a fluid communication extending between the inlet and the interior of said chamber, a second fluid communication extending between the interior of the chamber and the outlet, a two-position valve in said second communication, a prime mover having a first range of operating speeds representing abnormal operation and asecond range of speeds representing normaloperation, electrical meansv including a source of power for controlling the operation of said prime mover, a solenoid operator operatively connected to said electrical means between the source of power and the prime mover, said operator being movable to a first position during abnormal operation and a second position during normal operation of the prime mover, and ele rical means controlled by the operator and operatively connected to said second named valve for moving the latter to one of its positions when the operating speeds of said prime mover change from one range to the other.

4. A refrigeration control device, comprising a casing having an inlet and an outlet, a partition in said casing separating the interior thereof into an inlet chamber and an outlet chamber, said partition having an opening between said chambers, a cylinder formed within the inlet chamber,. a movable piston positioned within said cylinder; and being movable with respect to the partition for closing the opening therein, means for admitting fluid from the inlet chamber into the interior of said cylinder above the piston, pressure responsive means connected to the piston and positioned in the outlet chamber, said last named means being effective to move the valve to an open position when the pressure in the outlet chamber is less than a predetermined pres sure, and a passage extending between the interior of said cylinder and the outlet chamber for providing fluid communication between the outlet chamber and the interior of said cylinder to maintain pneumatic balance on oppositely disposed portions of the piston.

5. A refrigeration control device, comprising a casing having an inlet and an outlet, a partition in said casing separating the interior thereof into an inlet chamber and an outlet chamber, said partition having an opening between said chambers, a cylinder formed within the inlet chamber, a piston positioned within said cylinder and being movable with respect to the partition for closing the opening therein, pressure responsive means connected to the piston and positioned within the outlet chamber, said last named means bein effective to move the valve to an open position when the pressure in the outlet chamber is less than a predetermined pressure, means forming a first passage between the inlet chamber and the interior of the cylinder, means forming a second passage between the interior of said cylinder and the outlet chamber, said second passage being of substantially greater fluid flow capacity than the first passage to thereby maintain pneumatic balance on opposite sides of the piston, and fluid flow control means positioned in said second the interior of the cylinder and the outlet chamber.

6. In a refrigeration system, in combination, an evaporator, a compressor, a prime mover for driving the compressor, a control device adapted for connection between the evaporator and the compressor for controlling the flow of refrigerant to the compressor, comprising a main valve and an auxiliary valve which when opened renders the main valve operative and when closed renders the main valve inoperative, means for operating the auxiliary valve comprising an electric operator, a two-position switch operatively connected to said electric operator, and a mechanical operator operatively joined to the prime mover for moving the switch to one of its positions when the speed of the prime mover varies in either direction from substantially per cent of its rated speed,

7. A refrigeration control device, comprising a casing having an inlet and an outlet, a partition in said casing separating the interior of the casing into an inlet chamber and an outlet chamber, said partition having an opening between said chambers, a cylinder formed within the inlet chamber and depending from the upper surface of the casing and terminating at a spaced distance from the partition whereby the interior of the latter in the direction of the partition, a passage extending from the interior of the cylinder to the outlet chamber, valve means in said passage, a pressure responsive diaphragm in the outlet 7 cham e an c nected to said piston, a spring 13 operatively connected to said diaphragm for moving the piston away from the partition, and means for adjusting the pressure on said spring.

8. A refrigeration control device adapted for connection between an evaporator and a compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a pressure responsive valve within the casing between the inlet and the outlet, a cylinder formed within the casing and surrounding a portion of the valve, a passage extending between the inlet and the outlet and communicating with the interior of the cylinder, fluid flow control means in said passage, an electric operator connected to said fluid flow control means, a prime mover for driving the compressor, and a control device operatively connected between the prime mover and the electric operator for controlling the latter in response to a condition of the rime mover.

9. A refrigeration control device, comprising a casing having an inlet and an outlet, a partition in said casing separating the interior thereof into an inlet chamber and an outlet chamber, said partition having an opening between said chambers, a cylinder formed within the inlet chamber above said opening, a movable piston positioned within said cylinder for movement with respect to the partition for closing the opening therein, said piston having a portion extending through the opening into the outlet chamber, means for admitting fluid from the inlet chamber into the interior of said cylinder above the piston, and a flexible diaphragm secured to the portion of the piston which extends into the outlet chamber, one side of said diaphragm being subject to the pressure within the interior of the outlet chamber and its other side being subject to the pressure existing on the outside of the casing.

10. In a refrigeration system, in combination, an evaporator, a compressor, a prime mover for driving the compressor having a first range of operating speed representing a first condition and a second range of operating speed representing a second condition, and a control device adapted to be positioned between the evaporator and the compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a pressure responsive valve within the casing between the inlet and the outlet, a cylinder formed within the casing and surrounding a portion of the valve, a passage extending between the inlet and the outlet and communicating with the interior of the cylinder, a valve in said passage, an electric operator operatively connected to said valve, and a two-position switch electrically connected to said operator and operatively controlled by the prime mover in such a manner as to be held in one position during the first condition and moved to its other position during the second condition. I

11. In a refrigeration system, in combination. a fluid coil. a compressor connected to said coil to withdraw fluid from the coil, a prime mover for driving the compressor. and a control device adapted to be positioned between the coil and the compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a first valve member within said casing between the inlet and the outlet, a passage associated with said casing for by-passing arportion of the fluid between said inlet and outlet, a second valve positioned in said passage {or controlling the flow of fluid therethrough, and

a control device operatively connected between 75 2,318,933

said second valve and the prime mover for controlling the operation of said second valve in response to variations in speed of the prime mover.

12. In a refrigeration system, in combination, a fluid coil, a compressor connected to said coil to withdraw fluid from the coil, a prime mover for driving the compressor, and a control device adapted to be positioned between the coil and the compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a first valve member within said casing between the inlet and the outlet, a passage associated with said casing for bypassing a portion of the fluid between said inlet and outlet, 3, second valve positioned in said passage for controlling the flow of fluid therethrough, a source of power for operating the prime mover, and a control device operatively associated with said second valve and connected between the source of power and the prime mover for controlling the operation of the second valve in response to variations in the quantity of power flowing to the prime mover.

13. In a, refrigeration system, in combination, a fluid coil, a compressor connected to said coil to withdraw fluid from the coil, a prime mover for driving the compressor, and a control device adapted to be positioned between the coil and the compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a first valve member within said casing between the inlet and the outlet, a passage associated with said casing for bypassing a portion of the fluid between said inlet and outlet, a second valve positioned in said passage for controlling the flow of fluid therethrough, a flrstcontrol device operatively associated with the prime mover and responsive to the speed of the prime mover, and a second control device operatively connected between the first control device and the second valve for operating the valve in response to variations in the speed of the prime mover.

14. In a refrigeration system, in combination, a fluid coil, a compressor connected to said coil to withdraw fluid from the coil, a prime mover for driving the compressor, and a control device adapted to be positioned between the coil and the compressor for controlling the flow of fluid to the compressor, comprising a casing having an inlet and an outlet, a first valve member within said casing between the inlet and the outlet, a, passage associated with said casing for by-passing a portion of the fluid between said inlet and outlet, a second valve positioned in said passage for controlling the flow of fluid therethrough, circuit means including a source of power for controlling the operation of said prime mover, a solenoid operator in said circuit between the source of power and the prime mover, and a second solenoid operator connected between the flrst named operator and the second named valve for controlling the operation of said valve in response to variations in the flow of power to the prime mover.

FREDERICK M. JONES.

REFERENCES CITED UNITED STATES PATENTS Name Date Ehemann et al Dec. 5, 1922 Eilers et al. May 11. 1943 Number