US3811292A

US3811292A - Refrigeration fan control system

Info

Publication number: US3811292A
Application number: US00349023A
Authority: US
Inventors: W Hoenisch
Original assignee: King Seeley Thermos Co
Current assignee: King Seeley Thermos Co
Priority date: 1973-04-09
Filing date: 1973-04-09
Publication date: 1974-05-21
Anticipated expiration: 1991-05-21
Also published as: DE2431604A1; DE7422390U; US3815378A

Abstract

A control for a refrigeration system including a compressor, a condensor, an evaporator and an electrically energized fan for passing air in heat exchange relation with respect to the compressor, the control including a light source, fan control means responsive to the light source for varying the operating speed of the fan, and means for varying the magnitude of light transmitted to the fan control means from the light source in response to the refrigerant pressure in the refrigeration system.

Description

United States Patent 1191 Hoenisch Y 11] 3,811,292 [45] May 21, 1974 REFRIGERATION FAN CONTROL SYSTEM [75] Inventor: Walter Harold Hoenisch, Albert Lea, Minn. [73] Assignee: King-Seeley Thermos Co., Ann

Arbor, Mich. [22] Filed:' Apr. 9, 1913 211 App]. 110.; 349,023

3,402,565 9/1968 Maynard 62/183 3,613,391 10/1971 Harter 62/183 2,952,991

9/1960 St. Pierre 62/184 Primary Examiner-William J. Wye Attorney, Agent, ar'Fi'rm-l-laniess, Dickey & Pierce ABSTRACT A control for a refrigeration system including a compressor, a condensor, an evaporator and an electrically energized fan for passing air in heat exchange relation with respect to the compressor, the control including a light source, fan control means responsive to the light source for varying the operating speed of the fan, and means for varying the magnitude of light transmitted to the fan control means from the light source in response to the refrigerant pressure in the I refrigeration system.

' 20 Claims, 4 Drawing Figures PAiENTEUIAY 21 um I sum 2 or 2 REFRIGERATION FAN CONTROL SYSTEM BACKGROUND OF THE INVENTION In refrigeration systems employing a refrigerant compressor, it is desirable to obtain the maximum desired operating head pressure of the compressor as soon as possible after the system is energized and to maintain this head pressure throughout the freezing cycle. In air cooled condensing units, especially under low ambient temperature operating conditions, it is possible that the desired head pressure may never be obtained unless some provision is made to control the condensor fan speed. As will be appreciated by those skilled in the art, thehead pressure in such refrigeration systems is directly proportional to the refrigerant discharge temperature, and accordingly, it has been proposed to utilize a pressure switch which delays energization of the com-' pressor fan until the proper compressor head pressure is obtained; however, this results in erratic operation of the fan from full on to off and further results in large fluctuations in the head pressure. Additionally, such pressure switches result in the compressor fan operating at full r.p.m. when such full operating speed is not required. Alternatively, it has been proposed to utilize an electronic phase control device for operating the compressor fan. Such controls obtain the desired. fan speed by an external variable resistor. In some such systems, a thermister is used to vary the resistance to the phase control, although this approach has been found to be objectionable due to the slow response to changes in compressor head pressure due to the insuffi cient conductance of temperature changes to the thermister. This results in high peaks in the compressor head pressure at the initiation of a freezing cycle, with an additional disadvantage being that the thermister senses high ambient temperatures which cause the compressor fan to operate too fast on start-ups.

Another approach to obtaining maximum operating head pressure of refrigerator compressors is to use a pressure bellows to operate a potentiometer that gives improved control of the fan through the phase control. Disadvantages of the use of such bellows reside in the fact that they frequently involve cumbersome and costly operating mechanisms that require critical adjustments due to the short travel of the pressure bellows operating the associated potentiometers.

in accordance with the principles of the present invention, a new and improved fan control is provided.

which overcomes the various objectionable characteristics of similar type devices heretofore proposed in the prior art. The fan control ofthe present invention utilizes a light source that may be in the form of a small neon lamp and which is cooperative with aphotoelectric cell located in theelectrical circuitry of the compressor fan motor. The cell operates to provide-a variable resistance which increases or decreases with the amount of light supplied by the neon lamp that is transmitted to the cell. For "example, when a maximum amount of light is transmitted to the cell, the resistance provided thereby may be quite low. for example, in the order of 600-1000 ohms, whereas when the magnitude of the light is predeterminately decreased. the resistance provided by thecell may be in the order of 100.000 ohms. The method of varying the magnitude of the light transmitted from the neon lamp to the pho toelectric cell, and thus changing the resistance through the cell in relation to the discharge pressure of the refrigerator compressor, is accomplished by interposing a light masking element between the light source and the photoelectric cell. More particularly, the light masking element is mounted on the shaft of a Bourdon tube that is connected to the discharge end of the compressor, with the result that as the pressure increases, the light masking element is moved in a predeof the refrigeration system be in the order of 150 psi.

Accordingly, under low ambient temperature operating conditions, the fancontrol maintains the fan motor deenergized until the head pressure has increased to approximately psi. At this point, the fan will operate at a very slow speed and the operating speed will gradually increase as the head pressure increases. At approximately l50 psi, the control operates the fan at full rpm. and this operating condition will continue'until the head pressure begins to drop, at which time the fan speed will decrease accordingly.-

SUMMARY OF THE INVENTION This invention relates generally to refrigeration systems, and more particularly, to a new and improved control for operating the condensor fan in a manner so as to obtain predetermined headpressure in the compressor. v

It is accordingly a general object of the present invention to provide a new and improved fan control for refrigeration compressors. i

It is a more particular object of the present invention .to provide a new and improved fan control of the above-described character which includes a light source and a photoelectric element for varying the resistance supplied to the fan motor, and which further includes means for selectively controlling the magnitude of the light transmitted from the light source to the photoelectric cell in accordance with the discharge pressure of the compressor.

it is another object of the present invention to provide a new and improved fan control of the abovedescribed type wherein the means for varying the magnitude of the lightsupplied to the photoelectric cell comprises a light masking element which is cooperable with a pressure responsive Bourdon tube.

It is still another object of thepresent invention to provide a new and improved fan control for use'in refrigeration systems of thetype which can be'used in ice making equipment.

It is yet another object of the present invention to provide a new-and improved fan control of the abovedescribed type which is of a relatively simple construction, is economical to manufacture and which will have a long and effective operational life. v

Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. I

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF A PREFERRED EMBODIMENT Referring in detail now to the drawings and in particular to FIG. lthereof, a refrigeration system is representatively illustrated as comprising a conventional compressor 12, c'ondensor l4 and evaporator 16. As is customary in the art, the compressor 12 is provided with a cooling fan, generally designated by the numeral 18, which functions to selectively pass cooling air over the compressor during operation thereof. The fan 18 isshown as comprising an electrically energized motor 20, the operation of which is controlled by a 'fan control, generally designated by the numeral 22 and constructed in accordance'with the principles of the present invention. Generally speaking, the fan control 22 is I connected to the refrigeration system by means of a conduit 24 which is communicablewith the discharge side of the compressor 12, and by means of electrical conductors 26, 28 .which supply electrical energy to the fan motor 20. As will hereinafter be described in detail, the discharge pressure of the compressor 12 increases with the ambient temperature of the refrigeration system l0, and when the system 10 is operatingunde'r'low ambient temperature conditions, such as below 70F.,

the discharge pressure of the compressor 12 is too low for efficient operation. The proper compressor head pressure is particularly important when the refrigeration system 10 is operatively associated with ice making machines. especially where the refrigerant gases are utilized to heat the defrost water that is employed during the harvest cycle'of an ice making machine. Normally, in such ice making machines, .a head pressure of approximately 'l5 0'psi is desirable. In high ambient temperature conditions, the pressurcmay increase in excess of 200 psi; however, in low ambients, the fan control 22 of thev present invention will function to delay operation of the fan 18 until the head pressure.

has increased to approximately l00 psi. At this vpoint, the fan 18 will operate-at a very slow r.p.m. and gradually increasein speedas the head pressure of the compressor increases. At approximately I50 psi, the fan control'22 operates the fan at full r.p.m. and-the fan 18 2 will continue to so operate until such time as the head pressure of the compressor l2 begins to decrease, at

which time the fan speed'will decrease proportionately to reduce the headpressure.

Referring now in detail to the construction of the fan a pair of

mounting flanges

34 and 36 on the opposite ends thereof which are secured to the side 32 by means of suitable screws, bolts or the like 38. The

flanges

34, 36 are adapted to cooperate with the remaining portion of the housing (not shown) in operatively securing the side 32 thereto, as will be appreciated by those skilled in the art. The mounting flange 46 is formed with an aperture 40 within which a suitable grommet or the like 42 is provided, whereby to permit suitable electrical conductors to pass from the exterior of the hous-' ing 30 to the interior thereof, as is well known in the art. Generally speaking, the interior of the housing 30 contains a pressure sensing assembly 44, a phase control 46 and electrical terminal block 48, all of which components will hereinafter be described in detail.

Referring now in detail to the construction and operation of the pressure sensing assembly 44, the assembly 44 comprises a Bourdon tube, generally designated by the numeral 50, which is of a conventional, generally C-shaped configuration and is fabricated of a flattened suitable manifold block 52 which is communicable-via control 22 of the presentinvention, as best seen in FIGS. 2-4, the fan control 22 is contained or enclosed within a generally rectangular-shaped housing 30, one side 32 of which is depicted in the drawings. The interiorof the housing 32 is preferably of a dark color to avoid any light reflections, as. will hereinafter be appreciated. The side 32 of the housing 30 is provided with asuitable fluid fitting 53 with the conduit 24 that comrnunicates with the discharge side of the compressor 12, as previously mentioned. The end of the Bourdon tube oppositethat which is secured to the manifold block 52 is connected via a suitable mechanical linkages 54 with a segmental, gear56 which is meshingly engaged with-external teeth formed on a rotatable shaft 58. The mechanical linkages 54 and gear segment 56 operate such that upon an increase in pressure within the Bourdon tube 50 due to an increase'in pressure on the discharge side of the compressor 12, the shaft 58 will be'caused to rotate, for purposes to be hereinafter described. As shown in FIG. 4, theouterendof the shaft 58 is journal supported by suitable bearing means 60 operatively secured within a support plate or the like 62 attached to the inner side of the manifold block 52.

Disposed interiorly of the Bourdon tube 50 is a light source, generally designated by the numeral 64. The light source 64 preferably is in the form of a neon light 6.6 and is operatively mounted within a suitable support bracket 68 attached by suitable screws, bolts or the like 70 to the side'32 of the housing 30. The neon light 66 is connected viarsuitable electrical conductors 72, 74 with

terminals

76 and 78 of the aforementioned terminal block 48, with suitable resistor means (not shown), such as a I200 ohm resistoror the like, being provided in the electrical circuit to the .neon light 66 so that the samemay operate on a 1 15 volt source of electrical en- The light source 64 is cooperable with a light sensitive photoelectric device, herein referred to as a photoelectric cell and generally designated by the numeral 82. The photoelectric cell 82 may be of any one of a numberof different types of constructions and may light transmitted thereto. Preferably the photoelectric cell 82 embodied in the present invention consists of a cadmium sulphide cell of a construction well known in the art. Due to the sensitivity of the photoelectric cell 82, it is preferable to maintain the interior of the housing 30 shielded from exterior light sources, as previously mentioned. The photoelectric cell 82 is opera tively supported in a suitable carrier element, generally designated by the numeral 84, which is located adjacent and above the end of the shaft 58 which is rotatable by the Bourdon tube .50. The carrier element 84 is threadably mounted on a generally externally threaded shaft or screw element 86 which is in turn journal supported within a suitable internal bore formed in a mounting block 88 that is operatively secured to the side 32 of the housing 30'. The upper end of the shaft 86 is formed with a screwdriver receiving slot 90 by which the shaft 86 may be rotated, with the result that the carrier element 84 and photoelectric cell 82 mounted thereon will move toward and away from the axis of the shaft 58 and hence toward and away from a position generally in aligned confronting relation with respect to the light source 64. Thus, the control 22 may be adjusted in accordance with the desired head pressure in the associated refrigeration system. One side of the carrier element 84 is formed with an elongated slot 92 which is adaptedto be slidably engaged with an elongated guide member 94 having an upper, generally loop-shaped portion 96 that is adapted to be secured to the side 32 by means of a suitable screw, bolt or the like 98. As will be appreciatedby those skilled in the art, the interen'gagement of the slot 92 with the guide member 94 prevents rotation of the element 84 and photoelectric cell 82 upon upward and downward-movement thereof upon rotational adjustment of the shaft 86. The photoelectric cell 82 is mounted on the carrier 84 such that the light sensitive side thereof faces the light source 64, and the cell 82 is connected to the electric circuitry of the fan control 22 of the present invention by means ofa pair of electrical conductors 100 and 102 which are respectively connected to

terminals

104 and 106 of the terminal block 48.

the internal pressure within the Bourdon tube 50 is relatively low, for example, in the order of approximately 150 psi, the aperture 114 is in complete registry with the line of light transmission from the light source 64 to the photoelectric cell 82. In this condition, the maximum amount of light is transmitted to the photoelectric cell 82 which results in a minimum or zero resistance being interjected thereby into the fan control circuit. As the pressure within the Bourdon tube 50 decreases, for example, to approximately 125 psi, resulting in a predetermined amount of rotation of the element 108, the configuration of the control aperture 114 therein is such that approximately 25 percent of the light transmission from the light source 64 to the photoelectric cell 82 is blocked. Similarly, when the pressure within the Bourdon tube 50 drops still further, for example, to

' approximately 70 psi, the shape of the control aperture lri accordance with the present invention,.interposed between the-photoelectric cell 82 and the light source 64 isa light masking element, generally designated by the numeral 108. The element 108 consists ofa generally disc-shaped member which may be fabricated of a light impervious material, such as metal or the like. The masking element 108 isformed with a central opening 110 which is provided with a suitable mounting hub or the like 112 adapted to operatively secure the element 108 on the end of the shaft 58. With this arrangement, upon rotation of the shaft 58 due to a pressure change within the Bourdon tube 50, the masking element 108 will rotate about the axis of the shaft 58. The radial di-- mension of the masking element 108 is such that the element is adapted to interrupt or block the transmission of light from the light source 64 to the photoelectric cell 82; however, the element 108 is formed with a control aperture, generally designated by the numeral 114, which is of a preselected configuration such that when the element 108 is selectively rotationally positioned, a predetermined magnitude of light will be transmitted from the'light source 64 throughthe aperture 114 to the photoelectric cell 82. The shape oi" con 114 is such that approximately one-half the light from the light source 64 to the photoelectric cell 82 isblocked; Finally, the control aperture 1141s such that when the pressure within the Bourdon tube 50 drops to some predetermined minimum level, approaching zero psi, the aperture 114 will be moved entirely out of registry with the photoelectric cell 82 and light source 64, with the result that the masking element 108 entirely blocks the transmission of light therebetween. It will be noted that the present invention is not intendedto be limited to the specific construction of the masking element 108 hereinbefore described, since the element 108 'may assume various other shapes and maybe fabricated of various other materials. For example, the eletransmission therebetween is blocked, and as the clear.

portion of the disc moves into registry with thelight source 64 due to rotation of the shaft 58, a-selectively greater amount of light will be transmitted to the photoelectric cell 82, thereby achieving the abovedescribed results. it will also be n'oted that the particular configuration and location of the various components of the fan control 22 of the present invention are not necessarily limited to the arrangement shown in the drawing and. that such components could be mounted on a conventional printed circuit board having the various electrical conductors described herein .printed thereon, as will be appreciatedby those skilled in the art. Additionally, it will be seen that various means other than the adjustable shaft 86 may be provided for varying the magnitude of light transmitted to the cell 82 for a given desired head pressure. For example, instead of having the photoelectric cell 82 bemovable by means of the aforedescribed shaft 86, it would be possible to have the masking element 108 adjustably mounted upon the shaft 58, whereby the element 108 could be selectively rotatably positioned upon the shaft I 58 in accordance with the desired pressure of the comfiguration of the control aperture 114 is such that when I pressor l2.

The fan motor 20 of the fan '18 consists of a typical triacs, etc. As is well known in the art, the firing angle at which the control devices are caused to conduct may be controlled by the input circuit to the gate electrode of the control devices, thus varying the amount of energy fed to the fan motor 20. The phase control 36 and resistance profided by the cell 82 generally functions to control the input circuit of such a control device. More particularly, the phase control 36 is shown as being housed in a suitable enclosure 'or housing 118 which is secured to the side 32 of the housing 30 by means of suitable screws,-bolts or the like 120. The phase control may consist of any suitable known motor speed control which generally functions to rapidly switch off" and on the AC supply to the fan motor 20 by cutting off a fraction of the AC cycle. This, of course, is accomplished by controlling the phase angle of the AC wave at which the triac orother control rectifier is triggered. A suitable phase control is marketed by Omnetics Incorporated of Syracuse, New York, and is marketed under the trade name Omnephase. Suitable AC phase control models sold under the Omnephase trade name are models 602A and 1002A and typically have an input voltage characteristic of I20 volts, an off state voltage of 200 volts, a forward voltage drop of reasons; anon state current of 6-10 amps, a peak surgeon-state current of 100-200, and a peak off'st at e cfirr'nrdf 2 milliamperes. It will be appreciated, of

course; that various alternative AC phase controls may be utilized without departing from the scope of the present invention and that the aforesaid typical phase control devices are described merely byway of example. The phase control 46 is communicable with the which, for example, may consist of the electrical energy supplied to the compressor 12.

Assuming'that the photoelectric cell 82 is properly positioned with respect to the light source 64 and that V the light masking element 108- is properly rotationally positioned upon the shaft 58, so as to achieve the desired rotation thereof for agiven desirable range of pressure changes occurring within'the Bourdon tube 50 and originating at the-discharge side of the compressor 12. the operation of the fan control 22 of the present invention is such that when a minimum pressure condition exists within the compressor 12, the masking element 108 is rotationally positioned so as to prevent the transmission of light from the light source 64 to the photoelectric cell 82. Accordingly, the maximum amount of electrical resistance is introduced into the electrical circuit of the fan motor 20. Depending upon the particular type of photoelectric cell 82 which is utilized, this resistance may be in the order of 100,000 ohms or greater. As the pressure at the discharge end of the compressor 12 increases, the masking element 108 will be rotated, thereby causing a greater amount of light to be transmitted from the light source 64 to the photoelectric cell 82.-For example, when the pressure in the Bourdo'n tube. 50 reaches approximately 75 psi, approximately one-half of the light produced by the continue to increase with increased pressure in the Bourdon tube 50 until such time as the pressure therewithin is in the order of 150 psi, at which time virtually the entire amount of light produced by the light source 64 will be transmitted to the photoelectric cell 82. When the maximum amount of light is received by the photoelectric cell 82, the resistance introduced thereby is at a relatively low level, for example, in the order of 600 ohms or less, with the result that the fan motor 20 is operatingat virtually full r.p.m., thereby resultingin the maximum amount of air being passed over the compressor l2.

As previously mentioned, the fan control 22 of the present invention will find particularly useful application in low ambient temperature operating conditions, particularly where the refrigeration system 10 is utilized in an ice making machine or the like wherein the electrical circuitry of the fan control 22 of the present t defrost water is heated by the discharge gases of the refrigeration system. it will be appreciated, of course, that the principles of the present invention will find wide and varied application other than ice making equipment, where a small, compact, easily adjustable fan control is to be employed. 7

While it will be apparent that the preferred embodiment herein illustratedis wellcalculated to fulfill the objects stated abovefit will beappreciated that; the present invention is susceptible to modification, variation, and change without departing'from the scope-of the invention. r

I claim: s i

l. A control for a refrigeration system including a compressor, a condensor, an evaporator and an electrically energized fan for passing air in heat exchange relation to the compressor,

said control including a light -source,= fan control means responsive to said light source produced for varying the operating speed and means for controlling the magnitude of light trans! mitted to the fan control means from said light source in response to the said system.

2'. The invention as set forth in claim 1 which includes a Bourdon tube'operable in response to the re-- frigerant pressure in the compressor portion of said refrigeration system, which includes a photoelectric cell,

.wherein said means for controlling the magnitude of light transmitted from said light source comprises a light masking element movable in response to operation'of said Bourdon tube.

3. The invention as set forth in claim 2 wherein said masking element is rotatable about a predetermined axis in response to operation of said Bourdon tube to control the magnitude of light transmitted from said light source to said photoelectric cell.

4. The invention as set forth in claim 3 which includes an electronic phase control, and wherein said photoelectric cell is cooperable with said phase control to control the firing angle .at which the phase control supplies electrical energy to the cooling fan.

5. The invention as set forth in claim 3 wherein said I masking elementis of a generally disc-shaped configuof the fan,

refrigerant pressure inration and has means thereon which is selectively interposable between said light'source and said photoelectric cell for varying the magnitude of light transmitted therebetween upon rotation of said element.

6. The invention as set forth in claim 5 wherein said masking element is mounted on a rotatable shaft, and which includes mechanical linkage means actuable in response to operation of said Bourdon tube to rotate said shaft and said masking element thereon.

7. The invention as set forth in claim 6 which includes adjustment means for selectively varying the amount of light received by said photoelectric cell from said light source for a given pressure condition in said refrigeration system.

8. The invention as set forth in claim 7 wherein said adjustment means comprise means for movably supporting said photoelectric cell relative to said light source.

9. The invention as set forth in claim 1 wherein said control comprises a housing having a low light reflective interior, which includes a Bourdon tube and conduit means communicating said tube with the discharge side of the refrigeration compressor, wherein said light source is located adjacent said-Bourdon tube, which includes a generally circular shaped light masking element mounted for rotation about an axis arrangement generally coaxial of said Bourdon tube, which includes mechanical linkage means operatively connecting said Bourdon tube with said shaft, whereupon a change in pressure in said Bourdon tube results in rotation of said shaft, which includes a photoelectric cell disposed on the opposite side of said masking element from said light source, which further includes means on said masking element for varying the magnitude of the light transmitted to said photoelectric cell in response to changes in the rotational position of said masking element, and whereupon said refrigeration fan includes an AC motor whose speed is controlled by a control device, the firing angle of which is varied by the resistance of the input circuit of the gate electrode of the control device, and wherein said photoelectric cell is operable to change the resistance in said input circuit and thereby vary the amount of energy supplied from a suitable source thereof to said fan motor.

10. A fan control to be used with an electrically energized cooling fan for a refrigeration system, comprising.

a light source, v I an electrical circuit for supplying electrical energy to said fan and including light sensitive variable-resistance means,

means for controlling the magnitude of light transmitted from said source to said light sensitive means. and

means for operating said last-mentionedmeans in response to the refrigerant pressure in said system.

-ll. The invention as set forth in claim 10 wherein f refrigeration system.

12. The invention as set forth in claim 11 which includes a Bourdon tube operable in response to the re- 10' frigerant pressure in the compressor portion of said refrigeration system, and wherein said light sensitive means comprises a photoelectric cell.

13. The invention as set forth in claim l2 wherein said means for controlling the magnitude of light transmitted from said source to said light sensitive means comprises a light masking element movable in response to operation of said Bourdon tube.

14. The invention as set forth in claim 13 wherein said masking element is rotatable about a predetermined axis in response to operation of said Bourdon tube to control the magnitude of light transmitted from said light source to said photoelectric cell.

15. The invention as set forth in claim 14 which includes an electronic phase control, and wherein said photoelectric cell is in cooperation with said phase control to control the firing angle at which the phase control supplies electrical energy to the cooling fan.

16. The invention as set forth in claim 14 wherein said masking element is of a generally disc-shaped configuration and has means thereon which is selectively interposable between said light source and said photoelectric cell for varying the magnitude of light transmitted therebetween upon rotation of said element.

17. The invention as set forth in claim 16 wherein said masking element is mounted on a rotatable shaft, and which includes mechanical linkage means actuable in response to operation of said Bourdon tube to rotate said shaft and said masking element thereon. I

- 18. The invention as set forth in claim 17 which includes adjustment means for selectively varying the amount oflight received by said photoelectric cell from said light source for a given pressure condition in said refrigeration system. i

19. The invention as set forth in claim 18 wherein said adjustment means comprise means for movably supporting said photoelectric cell relative to said light source.

20. The invention as set forth in claim 11 wherein said control comprises a housing having a low light refle'ctive interior, which includes a Bourdon tube and conduit means communicating said tube with the discharge side of the refrigeration compressor, wherein said light source is located adjacent said Bourdon tube, which includes a generally circular shaped light masking element mounted for rotation about an axis arrangernent generally coaxial of said Bourdon tube, which includes mechanical linkage means operatively connecting said Bourdon tube with said shaft, whereupon a change in pressure in said Bourdon tube results in rotation of said shaft, which includes aphotoelectric cell disposed on the opposite side of said masking element from said light source, which further includes means on said masking element for varying the magnitude of the light transmitted to said photoelectric cell in response to changes in the rotational posit-ion of said masking element, and whereupon said refrigeration fan includes an AC motor whose speed is controlled by a control device, the firing angle of which is varied by the resistance of the input circuit of the gate electrode of the control device, and wherein said photoelectric cell is operable to change the resistance in said input circuit and thereby vary the amount of energy supplied from a suitable source thereof to said fan motor.

' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 1, Dated May 21, 1974 Inventoflx) Walter Harold Hoenisch It is certified that error appears in the'above-ideutified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 18, delete "com"; line 19, "pressor" should be --condenser--; line 27, "compressor" should be -cor1denser--; line 38, "compressor" should be --condenser-; line 55, delete "com-"; line 56, "pressor"'should be "condenser-n Column 2, line 36, "compressors" should be --c0ndensers-7-. Column 3, line 20, "compressor 12" should be "condenser 14"; line 22, 'd-el1ete "over"; llne 23, delete "the compressor" and ip'sert therefor -'-thereover- -r-.

T "columns, line 39, "compressor" should be "condenser"; 7 Q

' Signed and; sealed this 7th day of January 1975.

(SEAL) Attest: McCOY M. GIBSON. JR. c. MARSHALL DANN' Attesting Off leer. Commissioner of Patents FORM PC4050 (10-69) UlcoMM-Dc cove- 69 u.s. aoyuupmq rimrlus omc: you maps-an

Claims

1. A control for a refrigeration system including a compressor, a condensor, an evaporator and an electrically energized fan for passing air in heat exchange relation to the compressor, said control including a light source, fan control means responsive to said light source produced for varying the operating speed of the fan, and means for controlling the magnitude of light transmitted to the fan control means from said light source in response to the refrigerant pressure in said system.

2. The invention as set forth in claim 1 which includes a Bourdon tube opErable in response to the refrigerant pressure in the compressor portion of said refrigeration system, which includes a photoelectric cell, wherein said means for controlling the magnitude of light transmitted from said light source comprises a light masking element movable in response to operation of said Bourdon tube.

4. The invention as set forth in claim 3 which includes an electronic phase control, and wherein said photoelectric cell is cooperable with said phase control to control the firing angle at which the phase control supplies electrical energy to the cooling fan.

5. The invention as set forth in claim 3 wherein said masking element is of a generally disc-shaped configuration and has means thereon which is selectively interposable between said light source and said photoelectric cell for varying the magnitude of light transmitted therebetween upon rotation of said element.

9. The invention as set forth in claim 1 wherein said control comprises a housing having a low light reflective interior, which includes a Bourdon tube and conduit means communicating said tube with the discharge side of the refrigeration compressor, wherein said light source is located adjacent said Bourdon tube, which includes a generally circular shaped light masking element mounted for rotation about an axis arrangement generally coaxial of said Bourdon tube, which includes mechanical linkage means operatively connecting said Bourdon tube with said shaft, whereupon a change in pressure in said Bourdon tube results in rotation of said shaft, which includes a photoelectric cell disposed on the opposite side of said masking element from said light source, which further includes means on said masking element for varying the magnitude of the light transmitted to said photoelectric cell in response to changes in the rotational position of said masking element, and whereupon said refrigeration fan includes an AC motor whose speed is controlled by a control device, the firing angle of which is varied by the resistance of the input circuit of the gate electrode of the control device, and wherein said photoelectric cell is operable to change the resistance in said input circuit and thereby vary the amount of energy supplied from a suitable source thereof to said fan motor.

10. A fan control to be used with an electrically energized cooling fan for a refrigeration system, comprising, a light source, an electrical circuit for supplying electrical energy to said fan and including light sensitive variable resistance means, means for controlling the magnitude of light transmitted from said source to said light sensitive means, and means for operating said last-mentioned means in response to the refrigerant pressure in said system.

11. The invention as set forth in claim 10 wherein said refrigeration system includes a compressor and wherein said means for controlling the magnitude of light from said source to said light sensitive means comprises a movable member movable in response to the refrigerant pressure in the compressor portion of the refrigeration system.

12. The invention as set forth in claim 11 which includes a Bourdon tube operable in response to the refrigerant pressure in the compressor portion of said refrigeration system, and wherein said light sensitive means comprises a photoelectric cell.

13. The invention as set forth in claim 12 wherein said means for controlling the magnitude of light transmitted from said source to said light sensitive means comprises a light masking element movable in response to operation of said Bourdon tube.

17. The invention as set forth in claim 16 wherein said masking element is mounted on a rotatable shaft, and which includes mechanical linkage means actuable in response to operation of said Bourdon tube to rotate said shaft and said masking element thereon.

18. The invention as set forth in claim 17 which includes adjustment means for selectively varying the amount of light received by said photoelectric cell from said light source for a given pressure condition in said refrigeration system.

20. The invention as set forth in claim 11 wherein said control comprises a housing having a low light reflective interior, which includes a Bourdon tube and conduit means communicating said tube with the discharge side of the refrigeration compressor, wherein said light source is located adjacent said Bourdon tube, which includes a generally circular shaped light masking element mounted for rotation about an axis arrangement generally coaxial of said Bourdon tube, which includes mechanical linkage means operatively connecting said Bourdon tube with said shaft, whereupon a change in pressure in said Bourdon tube results in rotation of said shaft, which includes a photoelectric cell disposed on the opposite side of said masking element from said light source, which further includes means on said masking element for varying the magnitude of the light transmitted to said photoelectric cell in response to changes in the rotational position of said masking element, and whereupon said refrigeration fan includes an AC motor whose speed is controlled by a control device, the firing angle of which is varied by the resistance of the input circuit of the gate electrode of the control device, and wherein said photoelectric cell is operable to change the resistance in said input circuit and thereby vary the amount of energy supplied from a suitable source thereof to said fan motor.