US 3537509 A
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United States Patent Donald C. Ferdelman Dayton, Ohio Jan. 23, 1969 Nov. 3, 1970 General Motors Corporation Detroit, Michigan a corporation of Delaware Inventor Appl. No. Filed Patented Assignee CONTROL FOR HEAT PUMP 4 Claims, 3 Drawing Figs.
Field of Search References Cited UNlTED STATES PATENTS 3/1954 Ditzler et al.
3,173,476 3/1965 McCready 165/29 3,261,935 7/1966 Foster et al. 165/29 3,373,800 5/1968 Ferdelman 165/29 Attorney-Carl A, Stickel and w. E. Finken ABSTRACT: In the preferred form, a gang of six, six position selector switches having a common selector operating means selects either a heating cycle withmedinrn or high fan speed or a cooling cycle with either low or medium or high fan speed. A stage type double throw thermostat switch controls the refrigeration system for both heating and cooling. A thermostatic heat changeover double-throw switch substitutes resistance heating for reversed cycle heating when the latter becomes less desirable. An additional switch on the stage thermostat energizes an added resistance heater upon a greater fall in temperature.
(JONTROL, FOR HEAT PUMP This invention is directed to an improved control system for reverse cycle air-conditioners.
In my U.S. Pat. No. 3,373,800, issued Mar. 19, 1968, l provide a control for a reverse cycle air-conditioner providing only one fan speed for heating and two fan speeds for cooling. This control also requires a relay for energizing the fan motor during heating. I
It is an object of this invention to provide an improved control system for a reverse cycle air-conditioner providing addi tional selections of fan motor speeds for both heating and cooling and to eliminate the fan motor relay mentioned in the previous paragraph.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein preferred embodiments of the present invention are clearly shown.
IN THE DRAWlNGS F l0. 1 is a wiring diagram illustrating my improved control system for a reverse cycle air-conditioning system embodying one form of my invention;
FIG. 2 is a chart showing the closed positions of the various selector switches as "ON to perform the desired functions; and
FIG. .3 is a diagrammatic view of a reverse cycle air-conditioning system to which the control is applied.
Referring now more particularly to FIG. 3, there is shown diagrammatically a reverse cycle air-conditioning system including a compressor 20 having its outlet 22 connected to the reversing valve 24 which in the position shown delivers the compressed refrigerant to the outdoor heat transfer coil 26 which transfers heat from the refrigerant to the outdoor air. This transfer is greatly increased by the outdoor air fan 27 which is operated by the fan motor 36. The circulation of the outdoor air in heat transfer with the outdoor coil 26 causes the condensation of the compressed refrigerant which is forwarded through the restrictor 28 to the indoor heat transfer coil 30 where the refrigerant evaporates and absorbs heat from the air in the room to be cooled. This absorption of heat is increased by the indoor fan 31 which also is driven by the fan motor 36 and which circulates air from the room in heat transfer with the indoor coil 30. The evaporated refrigerant returns from the coil 30 through the reversing valve 24 to the compressor inlet 32. The compressor 20 is driven by the compressor motor 84. The reversing valve 24 is operated to reverse position by energizing a solenoid 34 which causes the compressor 20 to deliver the compressed refrigerant through the reversing valve 24 to the indoor coil 30 where it delivers heat to the room air circulated by the fan 31. This causes condensation of the refrigerant which then flows through the restrictor 28 in the opposite direction to the outdoor coil 26 where it evaporates and absorbs heat from the outdoor air circulated by the fan 27. The evaporated refrigerant then flows through the reversing valve 24 to the inlet 32 of the compressor 20.
In FIG. 1, the supply conductor L1 connects to the movable contacts 11, 12, 13 and 14 of a first gang of six position switches designated 1, 2, 3, and 4. respectively. The switch 1 includes one contact below a series of five dead contacts which is connected by the conductor 90 to the low-speed terminal 92 of the fan motor 36. The selector switch 2 has the second and sixth contacts connected by the conductor 135 with the medium speed terminal 137 of the fan motor 36. The No. 3 selector switch hasits third and fifth terminals connected by the conductor 94 to the high'speed terminal 96 of the fan motor 36. The fan motor 36 may have any form of control desired to provide low, medium-and high-speed terminals. In the form shown, the motor 36 is provided with a main winding 196, a phase winding 197, the medium-speed winding 195 and a low'speed winding 192. A running capacitor 97 connects the phase winding terminal 98 with the second supply conductor 40 for improved phase shift in both starting and running at all speeds; The junctions of the medium-speed winding 195 and the main winding 196 and the phase winding 197 are connected at the high-speed terminal 96. With this arrangement low-speed fan operation is provided in the lowest or full clockwise position, medium-speed operation is provided in the second and sixth positions while high-speed operation is provided in the third and fifth positions, with the fourth position having no connections for providing an OFF" position.
The supply conductor Ll also connects to the movable double throw switch member 42 of the stage type thermostat 44 which is responsive to room air temperatuke. This switch member 42 is of the snap action type and at higher room temperatures of the thermostat 44 such as, for example 78F, this contact 42 will be moved into engagement with an upper contact 46 which is connected by a conductor M6 to the movable contact 5 of the selector switch 6 which has its first, second and third contacts connected by the conductor 48 through the motor protector switch 80 and the conductor 82 with the compressor motor 84 which drives the compressor 20.
When the room temperature is lowered, for example to 72F., the lost motion connection of the stage thermostat 44 will move the double-throw switch member 42 into engagement with its lower contact 50 which connects through the conductor 52 to the movable contact 7 of the selector switch 8. The selector switch 8 has its upper fifth and sixth contacts connected by the conductor 141 to the double throw thermostatic heat changeover snap acting switch 143. The supply conductor L1 also connects through the movable contact 14 with the six position selector switch 4 having its fifth and sixth contacts connected through the conductor 121 with the solenoid 34 which is also connected by the conductor 123 to the second supplyconductor 40. All of the movable contacts of the selector switches are interconnected for substantially simultaneous movement by the common operating means shown diagrammatically and indicated by the reference character 109. Thus, whenever the gang of six selector switches is in the fifth and sixth position, the supply conductor L1 will be connected to the heat changeover switch 143 and the reversing solenoid 34'. The heat transfer switch 143 is positioned in heat transfer with the outdoor air and in the preferred form will remain in its lower position at outdoor temperatures above about 45F. In its lower position the snap action heat changeover switch connects through the lower contact 149, the conductor 145 and the auxiliary heater 147 which connects through the thermal overload protector 80 with the compressor motor 84 and the outdoor fan motor 29. The auxiliary heater 147 provides for quicker tripping of the thermal overload protector 80 during the reverse cycle operation for better protection of the motor.
When the temperature of the outdoor air falls below 45F., the snap-acting thermostatic heat changeover switch 143 will snap upwardly into engagement with its upper contact 151 connecting with the resistance heater 153 which connects through the temperature safety switch 139 with the second supply conductor 40. This provides more efficient heating at low outdoor air temperatures and prevents frosting the outdoor coil. The resistance heater 153 lS associated with the indoor coil 30 so that it is in heat transfer with the indoor air circulated by the fan 31.
The conductor 121 is connected by a branch conductor 58 to an additional snap actingmovable contact 54 of the stage thermostat 44. When the reverse cycle operation of the refrigerating system or the heater 153 is unable to maintain warm enough temperatures to satisfy the stage thermostat 44, a slight additional. fall in temperature will cause the snap act ing switch 54 to move downwardly into engagement with the contact 56. This contact connects through the conductor 60 with the auxiliary resistance heater 62 which also connects to the safety temperature thermostat 139. The energization of this auxiliary heater 62 provides additional heating sufficient to maintain the temperature of the room at the desired levels during extremely cold weather.
While the embodiments of the invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.
l. A reverse cycle refrigerating and control system including a refrigerant circuit provided with indoor and outdoor heat transfer units and a motor compressor unit provided with terminals and a flow control means for controlling refrigerant flow between the indoor and outdoor heat transfer units and an electrically operated reversing valve having terminals for changing the refrigerant connection between the motor compressor unit and the indoor and outdoor units, a fan and multiple speed fan motor having low-and medium-and high-speed terminals and a fourth terminal for circulating indoor and outdoor air in heat transfer with said indoor and outdoor units, electric heater means and terminals for heating the circulating air, a double-throw heat changeover switch having a doublethrow switch member and having one alternate terminal con- 1 nected to said heater means and having a second alternate terminal connected to a terminal of said motor compressor unit, a first supply conductor connected to said fourth terminal of said fan motor and to a terminal of said reversing valve and to a terminal of said heating means and to a terminal of said motor compressor unit, a second supply conductor, wherein the improvement comprises a first multiple selector switch means connected to said second supply conductor having a first selective contact means individually connecting to said low-speed terminal and having a second selective contact means individually connecting to said medium-speed terminal and having a third selective contact means individually connecting to said high-speed terminal of said fan motor and having a fourth selective contact means individually connecting to a terminal of said reversing valve, a stage-type dual thermostatic switch means having a double-throw switch member connected to said second supply conductor and having first and second double-throw terminals and having a second switch with one terminal connected to a terminal of said reversing valve and another terminal connected to a terminal of said electric heater, and second multiple selector switch means having a first contact means connecting said first double-throw terminal with a terminal of said motor compressor unit and having a second contact means connecting said second double-throw terminal to said double-throw switch member of said heat changeover switch.
2. A control system as defined in claim 1 in which interconnecting means are provided for said first and second multiple selector'switch means, said selector switch means being providcd with one position closing only said first contact means of said first selector switch means and said first contact means of said second selector switch means and being provided with a second position closing only said second contact means of said first selector switch means and said first contact means of said second selector switch means and being provided with a third position closing only the third contact means of said first selector switch means and said first contact means of said second selector switch means,
3. A control system as defined in claim 1 in which interconnecting means are provided for said first and second multiple selector switch means, said selector switch means being provided with one position closing only the second and fourth contact means of said first selector switch means and said second contact means of said second selector switch means and being provided with a second position closing only the third and fourth contact means of said first selector switch means and said second contact means of said second selector switch means.
4. A control system as defined in claim 3 in which interconnecting means are provided for said first and second multiple selector switch means, said selector switch means being pro' vided with three positions closing only the first contact means of said second selector switch means together with either the first or second or third contact means of the first selector switch means said selector switch means being also rovided with two additional positions closing only the secon contact means of said second selector switch means together with either the second and fourth contact means or the third and fourth contact means of said first selector switch means.