US3517523A - Air conditioner compressor and air fan speed controller - Google Patents

Description

June 30, 1970 BROWN ET AL 3,517,523

AIR CONDITIONER COMPRESSOR AND AIR FAN SPEED CONTROLLER Filed Aug. 26, 1968 3 Sheets-Sheet 1 I 1 l I s k Q 2: k a R s v m 67 70 v 75 MIC/2.9155 TIMPEeA me:

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AIR CONDITIONER COMPRESSOR AND AIR FAN SPEED CONTROLLER 3 Sheets-Sheet 2 Filed Aug. 26, 1968 8 ea 54 56 54a 50x 1 50 52 4 6 w 5 3 L 4P m y x n 5 e e n ww n M w r w 3 w I w n ;||l|!. B O :IIII Ill. .m a W y a Z r n a 6 w a O "J a 1 W HDB I H 11$ 6 Z I a3 w mu. /.m I0 I 9 w b 7. mm 0 p M w 4 II a W m m. b. 0 m FV\ L MM m',,...n\y 8 W a m m .0 O 6 m 0 0 N mwm W June 30, 1970 w, BROWN ET AL 3,517,523

AIR CONDITIONER COMPRESSOR AND AIR FAN SPEED CONTROLLER Filed Aug. 26, 1968 3 Sheets-Sheet 5 Fig] United States Patent Office 3,517,523 Patented June 30, 1970 3,517,523 AIR CONDITIONER COMPRESSOR AND AIR FAN SPEED CONTROLLER Harry W. Brown, Big Bend, Wis., and Donald W. Fries,

Decatur, Ala., assignors to Cutler-Hammer, Inc., Milwaukee, Wis, a corporation of Delaware Filed Aug. 26, 1968, Ser. No. 755,177 Int. Cl. F2511 17/00 US. Cl. 62--180 4 Claims ABSTRACT OF THE DISCLOSURE A thermostatic controller providing coordinated onoff control of a refrigerant compressor motor, and onoff and temperature variable speed control of an air circulating fan motor. A known form of thermostatic controller provides normal snap-action, on-ofi, switch operation at adjustable high and low temperatures. Movement of a lever in accordance with temperature change in the snap-action mechanism is adapted to additionally change the value of resistance in the gate control circuit of a bilateral thyristor in accordance with temperature decrease to slow down a fan motor. Such lever additionally affords opening of a second switch to deenergize the fan motor when a low temperature limit is reached. A modified form of the controller permits selection of either the aforementioned temperature variable speed control of a fan motor, or manual adjustment of the fan speed.

BACKGROUND OF THE INVENTION It is recognized in operation of air conditioners, particularly those of the small unit, or window mounted type, that it is desirable to reduce the velocity of the cooled air being delivered into a room or conditioned space in accordance with decrease in temperature to enhance comfort. Expedients heretofore used include providing several preset speeds for the air circulating fan motor, and more recently, variable speed control of the air circulating fan motor in accordance with the decrease in temperature of the room air.

The temperature variable speed control forms of controllers previously proposed, are sometimes complex, and are difiicult to coordinate or synchronize with the thermostatic on-oif control of the refrigerant compressors. In some cases existing controllers utilize separate thermal sensing elements for the refrigerant compressor on-oft control, and for the fan speed control. This makes for difficulty in synchronizing the tracking of the two sensing elements so that there will be fixed coordination between the on-off temperature points for the compressor and the temperature range of speed variation for the fan motor. Some controllers utilizing a single sensing element employ photoelectric systems which provide variation in intensity of a light as a means of generating variable input signals for effecting speed variation of the fan motor.

It is a primary object of the present invention to provide an improved controller for effecting coordinated onoflf control of a refrigerant compressor, temperature variable speed control, and on-off control of an air fan circulating motor in an air conditioner using a known form of thermostatic controller with a single thermally responsive power element.

Another object is to provide a semiconductor fan speed control circuit wherein an adjusting element of a gating control impedance element is mechanically adjusted in accordance with change in position of the thermally responsive power element.

A still further object is to provide a controller of the aforementioned kind wherein the temperature range over which fan speed control is provided, is adjustable within the limits of on-off operation of the compressor motor switch.

A further object is to provide a modified form of controller, in which automatic temperature variation of fan speed control, or manual variation of the fan speed can be selected as desired.

Other objects and advantages of the invention will hereinafter appear.

In the drawings:

FIG. 1 is a schematic view of an air conditioner which embodies the improved controller;

FIG. 2 is a diagram of a variable speed control circuit used in the improved controller;

FIG. 3 is a view in side elevation of an improved controller constructed in accordance with the invention;

FIG. 4 is a fragmentary view to larger scale showing certain of the details of the controller;

FIG. 5 is a view like FIG. 4, but showing the controller in a different operation condition;

FIG. 6 is a graph showing the relation between temperature and fan motor speed afforded by operation of the controller;

FIG. 7 is a schematic view of the controller when connected in a modified way with a fan motor; and

FIG. 8 is a schematic view of a modified form of controller affording either automatic or manual adjustment of the speed of a fan motor.

FIG. 1 shows an air conditioner 10, which comprises a refrigerant compressor 12 driven by an electric motor 13, an evaporator or heat exchanger 14, condenser 16, an air circulating fan motor 18, and an electric controller 20 for coordinating starting and stopping of motors 13 and 18, and for varying the speed of the fan motor 18 in accordance with the change in air temperature on the air intake side of the evaporator 14.

Controller 20 is provided with a temperature responsive element 22 of the thermal fluid filled type which has its end portion 22a positioned in close proximity to the air intake side of evaporator 14. As best shown in FIGS. 3 to 5, controller 20 comprises an electric switch 24, a diaphragm type power unit 26, a snap-acting switch operating unit 28 and a fan speed regulating circuit 30, mounted on a printed circuit board 32. Switch 24, diaphragm power unit 26, snap-acting operating unit 28 and temperature responsive element 22 comprise a known form of thermostatic switch unit 34 which is like that disclosed in the Kuhn Pat. No. 2,511,640.

Switch unit 34 has an upper mounting bracket 36 which supports switch 24 and operating unit 28. A channel-shaped bracket 38 with outwardly extending arms is secured along its bight to the upper surface of bracket 36. A shallow channel-shaped bracket 40 is secured by ma chine screws 42 to the arms 38a of bracket 38. A shaft extension 44 extends thereof a suitable clearance opening (not shown) in the bight of bracket 40 and is secured by a set screw 44a to the shaft of a loading spring adjusting screw 46 of switch unit 28. Printed circuit board 32 is secured to an upstanding arm 40a of bracket 40 by machine screws 48.

As best shown in FIG. 4, diaphragm power unit 26 comprises a cup-shaped diaphragm member 50 welded in a sealed relation to the outer cup-shaped case. 52. The movable wall 50a of diaphragm 50 is of a corrugated form, and a cupshaped loading spring follower or stirrup member 54 seats on its bottom surface against the bottom wall of diaphragm 50. A helically coiled loading spring 56 is disposed about on upwardly turned annular flange portion 54a of stirrup 54 and seats against the inside of the bottom wall of the latter. A nut 58 secured against rotation seats against the upper end of loading spring 56,

3 and its threaded bore accommodates the complementally threaded shank of adjusting screw 46.

Snap-acting switch operating unit 28 comprises two toggle levers 60 and 62. As shown in the aforementioned Kuhn Pat. No. 2,511,640, the levers 60 and 62 are both of generally hollow rectangular form, and are pivoted on opposite parallel side walls of a frame 66 by oppositely extending tabs (not shown) which engage with V-shaped notches formed in the frame side walls. A pair of parallel spaced apart tension springs 68 are anchored at corresponding ends in openings formed on the lefthand portion of lever 60 and the other ends of the springs are anchored in openings formed in the right-hand end portion of lever 62. The bearing notches are so positioned that the levers 60 and 62 have single stable toggle positions, namely, that shown in FIG. 3, to which they tend to return. As shown in FIGS. 3 and 4, lever 62 in stable position is defined by its engagement with the lower side of the head of an adjustable screw stop 69. The right-hand end portion of lever 62 depends downwardly at an angle and engages operating lever 70 of switch 24. The corresponding stable position for lever 60 is defined by the engagement of its left-hand end portion with inwardly turned tangs 66a of frame 66.

Stirrup 54 has vertically extending portions 54b formed on opposite sides of the cup portion 54a and elongated notches 540 are formed in the portions 54b. Tabs 60a extending outwardly from the parallel sides of lever 60 extend into the notches 54c and engage at the upper closed ends of the latter with the portions 541). On decrease in temperature the pressure in diaphragm chamber 50x will correspondingly decrease. Loading spring 56 with following action moves stirrup 54 downwardly and the engagement of the portion 54b of the latter with the tabs 60a of lever 60 causes the latter to pivot counterclockwise (as viewed in FIGS. 3, 4 and in its bearing notches.

A compound lever 72 is welded adjacent one end of the short side of its right angle member 74 to the left-hand end of lever 60. A flat spring member 76 is riveted adjacent one end to the longer side of member 74. Adjacent its other end spring 76 is riveted to a portion 78a of an operating member 78 which is preferably formed of molded insulating material. An adjusting screw 79 penegageable with a pivoted contactor 80, and projection 78d of member 78, and takes into a threaded boss formed adjacent the left end of the portion 74b of member 74.

A substantially flat barrier portion 78b is integrally formed with portion 78a, and a cam projection 78c extends outwardly from one side of portion 78b and a second cam projection 78d extends downwardly. As will hereinafter be more fully described, the projection 780 is engageable with a pivoted contractor 80, and projection 78d is engageable with the contactor 82 of an on-off switch 82.

FIG. 2 shows a circuit diagram of the motor speed regulating circuit 30, which is mounted on printed circuit board 32, together with a motor 18 which in the preferred form shown is of the permanent split capacitor or shaded pole type. The circuit board 32 is provided with terminals A, M, B, C, L and D. Terminal A is connected to the upper terminal of a capacitor C1, and to the upper, main conducting terminal of a semiconductor bidirectional triode th ristor 86. The lower main conducting terminal of thyristor 86 is connected to terminal M and to one end of a resistor 88 which is connected in series with capacitor C1 and to the other terminal capacitor C2.

Terminals B and C are connected together in series with a resistor 90, and in series with a semiconductor bidirectional diode thyrintor 92 to the gate terminal of thyristor 86. Also terminals B and C are connected in series with an adjustable resistor 94 to terminal D and to the upper main conducting terminal of thyristor 86. One end of a resistor 96 is connected to the point intermediate terminals B and C and resistor 94. The aforementioned contactor engages the resistance element of resistor 96. Terminal D has connection with contactor 80, and is connected to resistor 94, the upper main conducting terminal of thyristor 86 and the upper terminal of capacitor C1. Single pole switch 82 is electrically connected between terminals D and L.

As shown in FIG. 2, motor 18 has main winding 18a connected at one end to terminal M. At its other end it is connected to line L1 of a single phase A.C. voltage source in series with auxiliary winding 18b and a capacitor C3 to terminal M. Terminal L is connected to the other line L2 of the A.C. source.

In the particular motor connections shown in FIG. 2, terminals A, B, C and D of circuit board 32 do not have any external connections. However, as will hereinafter be explained in connection with FIGS. 7 and 8, these latter terminals permit another possible motor connection and for a modified form of manual-automatic control.

When switch 82 is closed, the main conducting terminals of thyristor 86 will be subjected to the full A.C. voltage. The control gate of thyristor 86 at the moment of closing of switch 82 will have all of the resistance of resistor 96 connected in circuit therewith. Consequently, thyristor 86 will conduct for minimum periods during each half-cycle of the A.C. voltage. As contactor 80 is pivoted clockwise a decreasing amount of resistance of resistor 96 will be connected in the gate control circuit of thyristor 86. Accordingly, C2 charges sooner on each half cycle to the value that causes thyristor 92 to conduct and render thyristor 86 conducting sooner in each half cycle. Thus, motor 18 will increase in speed as more and more resistance of resistor 96 is effectively removed from the circuit of the control gate of thyristor 86. It will be appreciated that counter-clockwise pivotal movement of contactor 80 will result in the increase of the amount of resistance of resistor 96 included in the gate control circuit of thyristor 86, and motor 18 will correspondingly decrease in speed.

Referring particularly to FIG. 3, it shows in some detail a preferred physical arrangement of the components of the fan speed control circuit described in conjunction with FIG. 2 mounted on printed circuit board 32 with the conducting foil portions on the reverse side shown in dotted lines. The thyristors 86 and 92 are mounted together on a heat sink comprising an inverted channel member 98d formed of a suitable heat conducting metal. Resistor 96 is suitably mounted on a Bakelite strip 100 which has a metal conductor portion 100a. Contractor 80 is pivotally mounted at 80a on board 32 and may be assumed to be provided with a torsion spring (not shown) which biases contactor 80 for counterclockwise pivotal movement.

Contactor 80 throughout its range of pivotal movement has continuous engagement with the lower surface of a fixed conductor strip 82b of a member 82 which also integrally comprises the switch contactor 82a. Member 82 is riveted to the board 32. Contactor 82a is provided with a contact 820 which is normally held in engagement with a stationary contact 102 secured to a right angle bracket 104 riveted to board 32. Member 82 is electrically connected to terminal D, and bracket 104 is electrically connected to terminal L.

An insulated cylindrical stop 106, is eccentrically secured on board 32, and as will hereinafter be explained, limits the counterclockwise movement of contactor 80. A right angle bracket 108 riveted to board 32 provides a stop to limit the clockwise movement of contactor 80.

Operation of the controller as a -whole will now be described. Let it be assumed that the temperature of the air emitting from the coils is initially above 75 F. Under these conditions the fluid pressure in element 22 and diaphragm chamber 50x will be such that the snap-acting toggle levers 60 and 62 assumes their stable positions depicted in FIG. 3. It may also be assumed that lever 70 has operated switch 24 to circuit closed condition. Thus, electric driving motor 13 for refrigerant compressor 12 will be energized. Refrigerant will accordingly be circulated under pressure to evaporator 14. Under these assumed conditions, all of the resistance of resistor 96 will be eitectively out of the gate control circuit of thyristor 86. Consequently, air circulating fan motor 18 will run at maximum speed. It may be assumed that the point in the diagram of FIG. 6 represents these initial conditions.

As the temperature of the air exiting from coil 14 decreases, the temperature will decrease in accordance with line P, and lever 60 pivots counterclockwise. Contactor 80 will be correspondingly pivoted in the counterclockwise direction, and during the first part of its travel will move on the bare conductor portion 100a of member 100. When the temperature has decreased to the value represented by the point Q on line P contactor 80 moves onto the resistor 96. As contactor 80 continues to move counterclockwise in response to a continued decrease in room air temperature, progressively more of the resistor 96 is inserted into the control circuit of thyristor 86. As hereinbefore explained, this results in thyristor 86 being rendered conducting progressively later in each half cycle of the applied A.C. voltage, and motor 18 correspondingly slows down in accordance with line R of FIG. 6.

When the temperature point S is reached it may be assumed that levers 60 and 62 toggle over center in a snap-action manner. Thus switch 24 will be opened by counterclockwise pivotal movement of lever 70 caused by clockwise snap-action pivotal movement of toggle lever 62. The toggle movement of lever 60 in the counterclockwise direction will result in some further movement of contactor 80 on resistor 96 to cause a corresponding sudden decrease in motor speed represented by the line T. At that point contactor 80 engages stop 106 and motor speed remains constant as depicted by the horizontal line -U of FIG. 6. As the air continues to decrease in temperature, lever 60 continues to pivot counterclockwise, and with it, lever 78. By the time point V is reached lever 78 has engaged its cam projection 78d against contactor 82a and moved the latter downwardly to disengage its contact 82c from contact 102. Thus motor 18 will then be deenergized to stop the circulation of air through evaporator 14 into the conditioned space.

When the temperature in the conditioned space again rises, the fluid fill in the diaphragm chamber 50x increases in pressure. Consequently, lever 60 is caused to pivot in the clockwise direction. This results in lever 78 being correspondingly pivoted in the clockwise direction, thereby to first disengage its cam projection 78d from contactor 82a, which under its inherent spring bias, then recloses its contact 820 with contact 102 to recomplete the power and control circuit for thyristor 86 and motor 18. The motor then runs at the speed indicated by line U until the temperature W is reached.

The continued clockwise pivotal movement of lever 78 results in its projection 78c being reengaged with contactor 80 to aiford corresponding clockwise pivotal movement of the latter. As the temperature of the conditioned space continues to rise, the clockwise pivotal movement of lever 80 on resistance 96 effects reduction of resistance in the control circuit of the gate of thyristor 86, and the latter then progressively conducts earlier in each half cycle of the A.C. voltage to increase the speed of the motor 18 in accordance with the line X in FIG. 6.

When the temperature represented by point Y is reached the levers 60 and 62 toggle with snap-action to these positions depicted in FIG. 3 wherein lever 70 causes switch 24 to reclose to again energize refrigerant compressor motor 13. Due to the snap-action movement of lever 60 contactor 80 moves olf resistance 96 onto portion 100a of strip 100, thereby causing a sudden further 6 increase in speed of motor 12 as represented by the line Z in FIG. 6.

Changing of the adjustment of screw 79, aifords a range of adjustment of the speed of motor 18 attained at the time snap-action operating mechanism 28 operates with snap-action to close switch 24. Such range is typified by range I shown in FIG. 6. The reduction in speed of motor 18 attained at the time of cut-ou snapaction operation of member 28 to open switch 24 is determined by the adjustment of cam stop 106 and the adjustment of the resistor 94. The distance F between lines Z and T represents the temperature differential between cut-in and cut-out operation of the snapaction mechanism.

FIG. 7 shows a slightly different hookup of the controller with a permanent split capacitor motor 110. As shown, phase windings 110a and 110b are connected at corresponding ends to supply line L1 of an A.C. supply. The other end of winding 110a is connected to terminal M on circuit board 32 and the other end of winding 11% is connected in series with a capacitor C4 to terminal D. It will be noted that with these connections for motor 110 current will only be varied in winding 110a. This results in a lower harmonic content in the motor current, and consequent reduction in mechanical vibration noise.

FIG. 8 shows a modified form of the controller adapted for selective automatic or manual control of the speed of air circulating from motor 18. In this modified form of controller, the circuit board interconnections between terminals B and C are removed, and terminals B and C are connected to a contactor 112, and to a stationary contact 114 of a combination selector switch-manual speed control unit 116. Contactor 112 together with contact 114, and a second stationary contact 118 provide a twoposition selector switch. Contact 118 is electrically connected to the slider 120a of a variable resistor which has the right-hand end of its resistance element 120b electrically connected to terminal A on circuit board 32.

It will be observed that with contactor 112 closed to contact 114, terminals B and C will be connected together as hereinbefore described in conjunction with FIG. 2, and the modified form of controller will thus function in accordance with temperature changes as previously described. If contactor 112 is alternatively closed to contact 118, it will then be observed that some portion of resistance element 12012, and slider 120:: of variable resistor will be connected. in circuit between terminals Av and B of the circuit board 32. Thus the periods of conduction of thyristor 86 during each half cycle of the A.C. voltage will be dependent upon the selected manual adjustment of slider 120a, and will be independent of temperature variations sensed by the thermostatic switch unit 34.

We claim:

1. The combination in an air conditioner with an electrical refrigerant compressor motor and an electrical air circulating fan motor;

(a of a thermally responsive power element movable in opposite directions in accordance with increase and decrease in temperature of ambient air;

(b) a first lever movable in accordance with said power element;

(c) a second lever movable with snap-action between two extreme positions whenever said first lever attalns given positions in moving in said opposite directions;

(d) electric switch means for controlling electrical power to said compressor motor operable between open and closed positions whenever said second lever moves toward one or the other of its extreme positrons; and

(e) control circuit means in circuit with said fan motor and connectable to a source of A.C. supply voltage comprising a semiconductor device having main conducting terminals connectable to said supply voltage and the fan motor, and having a control gate;

(f) means including an adjustable impedance device connected in circuit with said control gate and which when connected to said source of A.C. supply voltage aflFords adjustment of the conduction of said semiconductor device for variable periods of half cycles of the A.C. supply voltage in accordance with the adjustment of a mechanical adjusting element of said impedance device;

(g) and means affording movement of said mechanical adjusting element by the movement of said first lever to change the impedance of said impedance device in accordance with the change in air temperature to which said power element is subjected.

2. The controller in accordaance with claim 1, together with a second switch operable by said means affording movement of said mechanical adjusting element to interrupt power connected to said control circuit and the fan motor when the temperature to which said power element is subjected approaches a predetermined limit.

3. The combination according to claim 2, wherein said second switch has a contactor normally biased to contact closed positions, and wherein said means affording movement of said adjusting element is an insulating member which operates said contactor to contact open position following disengagement of said insulating member from said adjusting element upon completion of the latters range of impedance adjustment.

4. The controller in accordance with claim 1, together with a selector switch, and a manually adjustable resistor connected together with said selector switch and to said control circuit, said selector switch in one position rendering the aforementioned impedance element according to its adjustment effective to control the conducting periods of said semiconductor device, and said selector switch in another position rendering said manually adjustable resistor effective to control theconducting periods of said semiconductor device.

References Cited UNITED STATES PATENTS 3,385,077 5/1968 Marsteller 62l80 3,390,539 7/1968 Miner 62180 XR 3,398,889 8/1968 Bohannan 62180 XR 3,410,105 11/1968 Marsteller 62l80 MEYER PERLIN, Primary Examiner U.S. Cl. X.R.

qg gg g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,517 ,523 Dated June 30, 1970 Inventor) Harry W. Brown and Donald W. Fries It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 44, after 79 delete "penegageable with a pivoted contactor 80, and projection 78d" and substitute penetrates a clearance opening in spring 76 and portion 78a--;

line 53, "contractor" should be --contactor--;

line 71, "thyrintor" should be --thyristor--.

Column 4, line 49, "Contractor" should be --Contactor--.

slfiNED AN WLED Q Attest:

Emmi netm'h mm x. suaum, .m. Lmmsfing 0mm Oonmissioner of Patents

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