US2829504A

US2829504A - Air conditioning system for dwellings

Info

Publication number: US2829504A
Application number: US593409A
Authority: US
Inventors: Ralph C Schlichtig
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-06-25
Filing date: 1956-06-25
Publication date: 1958-04-08
Anticipated expiration: 1975-04-08

Description

R. c. SCHLICHTIG 2,829,504

AIR CONDITIONING SYSTEM FOR DWELLING-S April s, 1958 Filed June 25, 1956 5 Sheets-Sheet 1 /jj v.4 if

INVENTOR.

19(140/7 c sch/m;

R. c. SCHLICHTIG 2,829,504

AIR CONDITIONING SYSTEM FOR DWELLINGS s Sheets-Shet 2 April 8, 1958 Filed June 25, 1956 JNVENTCR. Aa/ph C. Sc/Micki? April 1958 R. C. SCHLICHTIG AIR CONDITIONING SYSTEM FOR DWELLINGS Filed June 25, 1956 5 Sheets-Sheet 3 INVENTOR. Raw a say/m April 1958 R c. SQHLHCHTIG 2,829,504

AIR COND ITIONING SYSTEM FOR DWELLINGS Filed Jfine 25, 1956 5 SheetsSheet 4 I I I April 8, 1958 R. c. SCHLICHTIG 2,829,504

AIR CONDITIONING SYSTEM FOR DWELLING-S Filed June 25, 1956 5 Sheets-Sheet 5 75 Ranks/17y Va/l e 2 V United States Patent AIR CONDITIONING SYSTEM FOR DWELLINGS Ralph C. Schlichtig, Dishman, Wash.

Application June 25, 1956, Serial No. 593,409

Claims. c1. 62--3) The present invention relates to improvements in an air heating and cooling system utilizing a reversible expansion-compression system which will, in cold weather, a

draw heat from outdoor air and supply it to a building unit air circulation system, and which will, during warm weather, draw heat from the building unit air circulation system and supply it to outside air.

I am aware that such reversible expansion and compression systems are known in the air conditioning field. The basic combination in such a system comprises an evaporator, a compressor charged with gas therefrom and a condenser which receives compressed gases from the compressor. When used for heating, the evaporator is positioned in contact with outside air to cause the fluid to pick up heat from the air. The fluid is then compressed to a higher pressure, and at this higher pressure, condensed to release the heat vaporization at a higher temperature in the building unit. When the system is used for cooling, the operation is reversed so that evaporation takes place in the condenser and condensation takes place in the evaporator, whereby heat is withdrawn from the building unit. and added to the outdoor air.

Such systems have several inherent weaknesses which have prevented their successful operation in colder climates. Perhaps the most serious weakness is the rapid decrease in heat delivering capacity of the system as the heat supplying outdoor air drops to a low temperature,

resulting in a drastic reduction of vapor pressure of the fluid in the evaporator and a consequent reduction of the charge in the compressor. Another weakness lies in the fact that as the temperature ofthe outer air goes down, more and more useful heat is carried back from the radiating condenser to the evaporator by the returning fluid, thereby reducing the net heat absorbed. A third weakness lies in the fact that when the outside air is near freezing, ice will be deposited on the evaporator, plugging it up and reducing its efficiency.

It is an object of the present invention to provide an expansion-compression system, reversibly operable to provide heating or cooling for a building unit, which is operable to draw heat from outside air partially warmed and dried by heat escaping from the building unit and also to draw heat from mild ground air drawn from a ground well.

A further object of the invention isto provide such a system having a compressor super charging system operated by heat returning with the fluid from the radiating condenser and additional heat from a water source.

A still further object of the invention is to provide such a system having an automatic rapid defrosting mechanism for the evaporator which utilizes the mild air drawn from the ground well and a water spray to melt the ice from the evaporator.

The nature and advantages of the invention will appear more clearly from the following description and the accompanying drawings, wherein a preferred form of the invention is shown. It should be understood, however,

2,829,504 Patented Apr. 8, 1958 that the drawings and description are illustrative only, and are not intended to limit the invention except insofar as it is limited by the claims. t i

In the drawings: 3

Figure 1 is a diagrammatic cross sectional view of a building unit provided with a heating and cooling system in accordance with my invention;

Figure 2 is a diagrammatic view of my heating and cooling system illustrating its utilization as a heating plant for the building unit;

Figure 3 is a diagrammatic view similar to Figure 2 but showing my invention utilized for cooling;

isure 4 is a sectional view taken on the line 4-4 of Figure 2, illustrating the positioning of the elements of the system in the air ducts of the heating and cooling unit;

Figure 5 is a sectionaal view taken onthe line 5-5' of Figure 2; t

Figure 6 is a wiring diagram showing the electrical connections for the heating and cooling system;

Figure 7 is a wiring diagram illustrating a slightly modified electrical circuit; and

Figure 8 is a fragmentary sectional view illustrating the reversing valve I employ in my system.

Referring now to the drawings, my invention is shown in Figure 1 as installed in a building unit 10. having a basement 11, a dwelling area 12 thereabove, an attic area 13 above the dwelling area, and a roof 14 covering the attic area. My heating and cooling unit generally indicated at 15 is located in the basement 11; The unit 15, shown more in detail in Figures 2 and 3 is comprised essentially of a compressor 16 driven by an electric motor 17 (see Figures 6 and 7), an evaporator 18 comprised of coiled tubing having thin heat conducting fins 19 thereon, and a condenser 20, also comprised of coiled tubing having heat conducting fins 21 thereon. The evaporator 18 and condenser 2%) are connected to the compressor 16 through a reversing valve generally indicated at 22 and described more in detail later herein.

The condenser 26 is positioned within a hot air bonnet 23 mounted atop the unit 15. The bonnet 23 is connected by a hot air duct 24 to the dwelling area 12 of the building 10. A cold air return duct 25 leads back from the dwelling area 12 to the bonnet 23. The bonnet 2.3 and the ducts 24 and 25 (it being understood, of course, that there are a multiplicity of each of the ducts 24 and 25 to supply air circulation throughout the building.) comprise the hot air circulation system for the building unit 1th. This system may be operated by gravity.

or may be a forced air system in which case a circulation fan 26, positioned in the bonnet 23, is employed.

The evaporator 18 of the unit 15 is positioned within a chamber 2'7 which is supplied with air from a duct 28. The unit is designed to extract heat from outside air, so the duct 28 is opened to the outside air. I have found that the efficiency of the system can be greatly increased if the duct 28 is opened into the attic 13 of the building 10 where it can gather outside air entering the attic 13 through ventilating openings 29, which air has already been somewhat warmed and dried by heat escaping from the dwelling area 12 below. This air is drawn into the duct 2% and through it to the chamber 27 by a fan 30 positioned in the chamber 27. After the air has flowed over the evaporator 18, it is exhausted to the outside by an exhaust duct 31;

Referring now more particularly to Figures 2 and 3, the compressor 16 is shown as having a cylinder 32 in which a piston 33 reciprocates, alternately reducing the cylinder space to compress and exhaust a charge of refrigerant fluid and enlarging the cylinder space to reduce the pressure therein and draw in a new charge of refrigerant. The refrigerant may be anysuitable fluid such as that sold under the trade name Freon. A pipe 34 extends from the cylinder 32 and has therein a check valve 35 which permits exhaust flow from the cylinder 32 but which prevents return flow. The pipe 34 connects to two pipes 36 and 37 which lead to opposite ends of the reversing valve 22. The pipes 36 and 37 have solenoid operated shut-off valves 33 and 39 therein. The reversing valve 22, shown diagrammatically in Figures 2 and 3, is shown in detail in Figure 8. The valve 22 comprises two

opposed valves

40 and 41 connected by a connecting rod 42. The

valves

40 and 41 are cup-sl1aped in cross section and have openings 43a in their side faces. Each

valve

40 and 41 has an inwardly extending skirt 42b thereon as shown in Figure 8. The

valves

40 and 41 are slidably mounted in cylinders 40a and 41a which have valve seats 40b and 41b therein. The

valves

43 and 41 are so arranged thatwhen one is seated in its valve seat, the other is positioned near the outer edge of its cylinder. Each of the cylinders 40a and 41a has a port 400 and 410 at its outer end to which the pipe 36 or 37 is connected. The cylinders 40a and 41a have

second ports

40d and 41d near their inner ends to which the evaporator 18 and the condenser 20 are connected, the condenser 24 being connected to the port 40a and the evaporator 18 being connected to the port 41d. The cylinders 40a and 41a have enlarged portions 4% and 41e adjacent the ports 40d and 41a. The intermediate portion of the reversing valve 22 between the cylinders 40a and 41a is connected by a return line 43 which leads back to the intake port of the compression cylinder 32. A check valve 44 in the line 43 prevents exhaust flow from the cylinder 32 into the line 43.

With the construction just described, manipulation of the two pilot operating solenoid valves 38 and 39 causes pilot operation of the reversing valve 22 to shift positively to direct compressed refrigerant into either the condenser 20 or the evaporator 13 without waiting for pressure to become equalized on the two sides, and to direct refrigerant from the remaining unit back into the compression cylinder 32. When the solenoid valve 38 is open and the solenoid valve 39 closed, as shown in Figures 2 and 8, the compressed refrigerant in the pipe 34 is free to enter the cylinder 40a of the valve 22 but cannot enter the cylinder 41a. The high pressure fluid flows into the cup of the valve 40 and causes it to move positively against its seat 40b. This positions the openings 42a in the enlarged portion 4% of cylinder 40a and allows the compressed refrigerant to flow through the port 40d, thereby admitting the compressed refrigerant to the condenser 20. When the valve 40 is so seated, the valve 41, not subjected to pressure since the solenoid valve 39 is closed, is forced toward the outer end of the cylinder 41a. In this position the refrigerant in the evaporator 18 is free to enter the port 41d, pass into the central portion of the valve 22, and through the line 43 to the compression cylinder 32. When the solenoid valve 33 is opened and the solenoid valve 38 is closed, as in Figure 3, the valve 22 is reversed and compressed refrigerant flows into the evaporator 18 while refrigerant in the condenser flows into the return line 43. In this instance, the functions of the

members

18 and 20 are reversed, the member 20 acting as an evaporator and the member 18 acting as a condenser. The skirts 4212 are so positioned that as the

valve

41 or 41 moves toward its seat 40b or 41b, the skirt 42b closes the opening in the seat before the slot 42a is moved to the enlarged portion 40:: or 41e of the cylinder 40a or 41a. This prevents refrigerant from flowing directly from either line 36 or 37 into the return line 43.

The unit, set up for operation as shown in Figure 2, acts as a heating system. The compressed refrigerant is indicated in the drawings by thickly dotting the pipe area. The evaporated refrigerant is indicated by lightly dotting the pipe area. The condensed refrigerant is indicated by double cross hatching the pipe area. Refrigerant in the compression cylinder 32 is compressed by the piston 33 and fed through the pipes 34 and 36, and the cylinder 40a, to the condenser 20. The compressed refrigerant is at this time at a relatively high pressure and temperature. As the refrigerant flows through the condenser, the cooler air in the bonnet condenses it, lowering the pressure and temperature. Condensation, of course, releases heat from the refrigerant which is transferred to the air in the bonnet 23. After the refrigerant has passed through the condenser 20, it flows through a pipe 45 which joins another pipe 46. Reverse flow in the pipe 45 is prevented by a check valve 47. When the refrigerant, now a liquid and having experienced a pres-sure and temperature drop but still relatively warm, reaches the pipe 46, most of it flows into a receiving vessel 48, but due to a capillary restriction 46a in the pipe 46 between the vessel 48 and the connection of the pipe 45, a portion of the refrigerant flows to a super charging evaporator to be described later herein. Liquid reaching the vessel 48 is prevented from flowing in reverse by a check valve 46!) in the line 46.

The liquid in the receiving vessel 48 flows out through a line 49 to a heat exchanger 50, the function of which will be described later herein. In the heat exchanger 50, the temperature and pressure of the refrigerant are lowered. From the exchanger 50, the refrigerant flows through a pipe 51 which leads to the low temperature, low pressure, evaporator 18. A thermal regulating expansion valve 52 in the pipe 51 at the connection thereof with the evaporator 18 expands the now cold refrigerant into a vapor. The valve 52 is not shown in detail since it is well known and in common use in the refrigeration industry. A check valve 53 in the line 51 ahead of the valve 52 prevents reverse flow.

As hereinbefore described, the evaporator 18 is positioned in the chamber 27 and in a stream of outside air. Heat from this air is absorbed by the expanding refrigerant in the evaporator 18. The vaporized refrigerant is drawn from the evaporator 18 through the reversing valve 22 and into the return line 43 to the compression cylinder 32. As the piston 33 moves down in the cylinder 32, a charge of this vapor is drawn into the cylinder 32.

The portion of the system heretofore described operates in substantially the same manner as a common heat pump. I have found, however, that under common cold weather conditions, the refrigerant vapor in the evaporator 18 is at such a low pressure, for example, about 18 p. s. i. absolute in the case of Freon when the outside air is at 5 F., that the charge admitted to the cylinder 32 on each intake stroke of the piston 33 is too small to cause the condenser 20 to radiate enough heat to sufiiciently warm the air in the bonnet 23. I therefore provide a supcrcharging apparatus for the cylinder 32. I have found that the rela tively warm liquid in the receiving vessel 48 is subject to a certain amount of evaporation and produces vapor of considerably higher pressure than that in the evaporator 13. This vapor is utilized to supercharge the cylinder 32 by providing a line 54 from the receiving vessel 4'3 to a port 55 near the bottom of the cylinder When the piston 33 reaches the bottom of its stroke this port 55 is uncovered, and the higher pressure vapor from the line 54 rushes in to increase the vapor charge. By providing a venturi restriction 56 in the line 54, and by providing a connecting line 57 from the return line 43 to the venturi restriction56, the rush of vapor through the line 54 and through the venturi restriction 56 is made to draw additional vapor from the evaporator 18 through the line 57 by venturi effect to further increase the charge in the cylinder 32. With this construction the heat carried from the condenser 20 is utilized to increase the charge of the cylinder 32.

To further supercharge the cylinder 32, a supercharging evaporator 58 is utilized. This evaporator 58 is connected to the line 46 and receives that portion of the refrigerant from the line 45 which is diverted by resistance to flow at the restriction 46a. A thermal regulating expansion valve 59 expands the refrigerant fiowing into-the supercharging evaporator 58. The evaporator 58 is positioned in a duct 60 which opens at theupper end thereof into the charnher 27 as shown at 61. The duct 66 is connected to an air well 62 constructed beneath. the building unit It). The air well 62 provides a year around source of mild air, non mally in the neighborhood of 50 F. in temperate zones. This mild air, though insuliicient in volume to provide the entire heat source for the building unit it), is capable of producing sufficient mild ground air to operate the evaporator :78. Since the ground air is of a higher temperature than the outside air during the months when the system described here is used for heating, the supercharging evaporator 58 may operate at a considerably higher pressure than the main evaporator 13. The evaporator 58 feeds the vapor therein through a pipe 63 which connects with the pipe 54 adjacent the supercharging port 55. The pipe 63 passes through the heat exchanger 56 and the vapor therein receives further heat from the refrigerant in the exchanger 56. Additional heat can be supplied from a water jacket 50a to the vapor in the pipe 63. In this manner the heat carried from the condenser 20 by the liquid refrigerant is removed to cool the liquid refrigerant flowing to the main. evaporator 18 sufficiently to allow that unit to operate efhciently. This heat is then added to already vaporized refrigerant used to supercharge the compression cylinder 32, whereby to increase the output of the condenser 20 and the intake of the evaporator .18. cylinder 32 through the lines 54 and 63, the pressure in the cylinder 32 at the end of the intake stroke of the piston 33 can be increased from about 18 p. s. i. absolute to as much as 70 p. s. i. absolute, in the example given ereinbefore. This, of course, results in a great increase in the heat radiating efiiciency of the condenser 20. In addition, the removal of heat from the liquid going to the evaporator 18, results in an increase in the heat gathering It is possible that by supercharging the capacity of the evaporator 18. 1 have found substantial increases in the heat gathering efiiciency in tests of the machine.

To further increase this heat gathering capacity, a second heat exchanger 64 may be included in the line 51 and positioned in the ground air duct 60 as shown in Figure 2. With this constructiomheat remaining in the liquid flowing to the evaporator 16 after passing through the exchanger 50 may be extracted. This exchanger 64, however, only extracts a small portion of heat and may be omitted as in Figure 3, without substantial loss to the system. i i

As hereinbefore described, the main evaporator 13. is exposed to outside air in the chamber 27 and extracts heat therefrom. Moisture in the air tends to collect on the evaporator 18, clogging the space between the fins 19 and restricting the flow of air through the chamber 27. This frost reduces the efficiency of the evaporator 18, so it is desirable to provide means for defrosting the evaporotor 13 at intervals. The present invention includes a defrosting mechanism which will quickly and automatically defrost the evaporator 18 when necessary. I have found that such defrosting may be quickly accomplished by merely terminating the operation of the system for a few minutes, during which time the mild ground air is drawn over the coils of the evaporator 18 to melt the ice thereon. A spray of relatively warm water may be included to speed the defrosting. The means for accomplishing this result will now be described.

in the chamber 27, two temperature sensitive elements 65 and 66 are positioneione on the upstream side of the evaporator 18 and one contacting the evaporator, as shown in Figure 2. The bulbs 6:3" and 66 have lines 67 and 63 leading from the top thereof to a control unit generally indicated at These bulbs 65 and 66, shown more clearly in Figure 6, are partially filled with a liquid and contain in addition, vapor of the same substance. As the temperature of the substance in the bulbs and 66 changes, the vapor pressure in the bulbs changes, in ac cordance with well known principles. In the control unit 69 and connected to the

lines

67 and 68 are two opposed diaphragms 70 and 71 (see Figure 6), which are connected together by arod 72. It will be understood that if the temperature of the bulb 65 and the temperature of the evaporator 18 contacting the bulb 66 remain equal, the pressures in the diaphragms 70 and 71 will remain equal and there will be no movement of the rod 72. Hot ever, should a temperature difierential exist between the bulbs 65 and 66, the diaphragm of the bulb subjected to the highest temperature will expand and push the rod 72 toward the other diaphragm. With the bulbs 65 and 66 positioned as shown in Figure 2, the bulb 65 will be at the temperature of the air before heat is extracted by the evaporator 18, while the bulb 66 will be at the temperature of the evaporatorltl. As the evaporator 13 ices up, iess and less air will be allowed to pass through the chamber 27 and consequently there will be a greater temperature drop in the air that does pass, causing a greater temperature differential between the bulbs 65 and 66. The bulb 65 always being at the higher temperature, will tend to expand the diaphragm 70 to move the rod 72 toward the diaphragm 71. A bias spring 73 prevents actual motion until the temperature differential reaches a predetermined amount, but when this amount is exceeded, indicating considerable icing of the evaporator 13, motion will occur. Movement of the rod 72 will actuate a switch 74, shown in Figure 6, moving it from a normally closed contact 75 to a normally open contact 76. The switch 74 is connected to a line 77 which extends to the voltage source. The normally closed contact 75 is connected to a line 73 which leads through a time delay switch 79 to a relay 8%). The switch 80a of the relay 80 is interposed in a line 81 extending from the voltage source to the motor 17 of the compressor 18, and to the hot air circulation fan 26. V hen the relay 80 is energized, the compressor motor 17 and fan 26 are energized. When the switch 74 disengagcs from the contact 75, the relay 80 is deenergized, stopping the compressor 16 and fan 26. At the same time the cornpressor 16 is stopped, it is necessary to close off the source of outside air from the chamber 27, and to open the chamber 27 to the ground air duct 60 to permit the mild ground air to pass around the evaporator 1.8 and melt the ice thereon. To accomplish this, I provide a damper 82, positioned as shown in Figures 2 and 3 at the entrance to the chamber 27. When the damper 82 is in the position shown in Figure 2, it permits outside air to enter the chamber 27 while blocking an opening 83 from the duct 60. The damper 82 is connected to a reversible motor 84 which has a clockwise winding and counterclockwise winding. The counterclockwise winding. connected by a line 85 to the line 81 supplying power to the compressor motor 17 and fan 26. A spring closed switch 86 is interposed in the line 85 and positioned on the wall of the chamber 27 above the opening 83 leading to the duct 60. When the switch 74 is engaged with the contact 75 and the compressor 16 is operating, the motor 34 will drive counterclockwise to swing the damper 82 to shut the opening 83 until the damper engages and opens the switch 86. The clockwise winding of the motor 84, however, is connected by a line 87 to the normally open line switch contact 76. A spring closed switch 88 is interposed in the line 87 and positioned as shown in Figure 2, on the wall of the chamber 27 above the entrance of the outside air duct 26. When the switch 74 is moved against the contact 76 in defrost position, current will flow through the line 87 and drive the motor 84 clockwise until the damper' 82 closes the entrance to the duct 28 and opens the switch 88. In this position, the damper S2 permits the mild ground air to pass over the evaporator 18.

'7 In order to prevent any flow of refrigerant through the evaporator 18 during defrosting, a solenoid valve 89 is positioned in the line 51 ahead of the expansion valve 52. The solenoid valve 89 is connected by a lead 90 to the switch contact 75 so that when the switch 74 swings to the defrost position, the solenoid valve 89 is deenergized and closed.

When the defrosting is completed, the large temperature differential between the bulbs 65 and 66 will be decreased, and the rod 72, aided by the bias spring 73 will move the switch 74 back to the normally closed contact 75. At this time, however, considerable moisture may still remain on the evaporator fins 19, so it is undesirable to flow cold air over the fins 19 at once. The time delay switch 79 placed in the line 78 prevents the damper and corn

pressor motors

84 and 17 from being energized immediately, and gives the moisture time to run oil. This switch 79 consists of a bi-metallic switch 79a, which is closed when heated, and a heater 7%. When the current through the line 78 is interrupted during defrosting, the switch 79a cools and opens. When the switch contact 75 is engaged after defrosting, current is passed through the heater 7%. After sufiicient time has elapsed to heat the switch 79a, it closes to start the

motors

17, 26 and 84.

As shown in Figure 6, the lead 77 which supplies line current to the switch 74, extends to one contact of a switch 91 which controls the operation of the unit as either a heating or cooling unit. When the switch 91 is in the position shown in Figure 6, the defrosting mechanism is energized for use during heating. The solenoid valve 38 is conected to the lead '77 so as to be energized during heating to open the pipe 36 and maintain the reversing valve 22 in the heating position. A solenoid valve 92, positioned in the pipe 54, is also electrically connected to the line 77 so that it is energized to open the pipe 54 during heating. When the unit 15 is to be used for cooling, the switch 91 is turned to the opposite position where it connects the voltage source to a lead 93 extending to a relay 94. The switch 94a of the relay 94 is interposed in a line 95 which extends from the voltage source to the compressor motor 17 and fan 26. When this relay 94 is energized, the

motors

17 and 26 are energized through line 95. The line 85 to the counterclockwise winding of the damper motor 84 is connected to line 95 so that when the switch 91 is turned to cooling position, the damper motor 84 will swing the damper 82 to close off the entrance 83 from the duct 60. The defrosting mechanism and the solenoid valve 38 are deenergised and valve 38 is closed.

The solenoid valve 39, however, is connected to the lead 93 and is energized to open the pipe 37 and to cause the reversing valve 22 to move to the position shown in Figure 3. The solenoid valve 92, positioned in the line 54, is also deenergized to close the pipe 54, since during the period when the unit 15 is operating as a cooling system, supercharging is unnecessary. The fan 30, positioned in the chamber 27, is intended to operate at all times, including the defrosting periods, so it is electrically connected, through a lead 96 to the voltage source. A switch 97 is interposed in the line 96 and ganged with the switch 91. The switch 97 is so connected as to close the line 96 when the switch 91 is in either the heating or cooling position.

Figure 7 illustrates a somewhat modified circuit for V the unit 15 wherein defrosting is accomplished in a different manner. With the circuit illustrated in Figure 7, the defrosting switch 74 operates between a normally closed contact 75 and a normally open contact '76 in the same manner as shown in Figure 6 and controls the

motors

17, 26 and 84 and the solenoid valve 89 through

circuit elements

78, 79, 80, 81, 85, 86, 87, 88 and 90, as in the circuit shown in Figure 6. However, the operation of the switch 74 is different. In the form of the invention shown in Figure 7, the switch 74' is ganged to a switch 98a of a relay 98. One side of the relay 98 and the switch 98a are connected by a lead 99 to the contact of a single pole, single throw switch 100, the other side of which is connected to a line 101 which extends to one contact, a heating and cooling control switch 91' which serves the same function as the switch 91, that is, to switch the unit 15 to either heating or cooling position. The switch is connected to a control rod 102 which in turn is connected to a diaphragm 103. The diaphragm 103 is connected by a pipe 104 directly to the evaporator 18. With this construction, the vapor pressure in the evaporator 18 is communicated to the diaphragm 103. So long as suflicient vapor pressure exists in the evaporator 18 the pressure of the diaphragm holds the switch 100 closed, allowing current to flow from line 101 through line 99 to the relay 98, maintaining both the ganged switches 98a and 74' in their normally closed positions. However, should the pressure in the evaporator 18 fall below a predetermined level, a bias spring 105 will force the diaphragm 103 to partially collapse and allow the switch 100 to open. In this event current will no longer flow to the relay 98 through the lead 99. The relay will not, however necessarily be deenergized, for an alternate current path is provided by a lead 106 which extends to the switch 98a of the relay 98 from the current supply line 101. This lead 106 has interposed therein a cam operated switch 107 which is opened and closed at selected intervals by a cam 108 driven by a motor 109. If, at the time the switch 100 is opened by insufficient pressure in the evaporator 18 (caused by icing conditions), the switch 107 is closed, the relay 98 will remain energized by current flow through its own switch 98a. Until the next periodic opening of the switch 107, the relay 98 will remain energized and the defrosting switch 74 will remain in normally closed position. If the switch 107 opens while the switch 100 is open, then, and only then, will defrosting occur. This circuit provides for defrosting based upon the pressure within the evaporator 18, but provides for protection against accidental defrosting caused by transient pressure fluctuations in the evaporator 18 caused by other than icing conditions. In the modified circuit, the fan 30 is energized through a line 96 controlled by a switch 97" ganged with switch 91' substantially as in the circuit of Figure 6.

If desired, the defrosting may be augmented by a spray of water from a water pipe 110 mounted above the evaporator 18. The pipe 110 has a solenoid operated valve 111 therein which is electrically connected to the switch contact 76 or 76', as shown in Figures 6 and 7. When the

switch

74 or 74 moves against contact 76 or 76 in the defrost position, the valve 111 is energized and opened to spray water over the evaporator 18 to assist in defrosting. The valve is closed when the switch 74 or 7 4' returns to normal position.

Figure 3 illustrates the operation of the unit 15 as a summer cooling system. When the unit 15 is to be so used, the switch 91 or 91 is turned to the cooling position so as to cut out the defrosting mechanism, close the

solenoid valves

38 and 92, open the valve 39, and insure that the damper 82 is moved to close the mild air opening 83. Now, compressed refrigerant flows from pipe 34 through pipe 37 and reverses the valve 22 by positively seating valve 41 against its seat 41b. The hot compressed refrigerant vapor is then passed through port 41d and into the member 18 which now operates as a condenser, cooled by the outside air inthe chamber 27. The condensed and cooled refrigerant flowing from the member 18 cannot flow into the line 51 due to the check valve 53, so a pipe 112 is provided which connects to the member 18 adjacent the expansion valve 52. The pipe 112 carries the refrigerant to the' receiving vessel 48. The check valve 113 in the line 112 prevents flow from the receiver 48 to the member 18 during heating operations. From the receiver 48 the liquid refrigerant flows through line 49, exchanger 50 and into line 51 and the second heat exchanger 64 where it is cooled by the mild air in the duct 60. There is no flow of vapor-through the pipe 54 due to the closed solenoid valve 92, nor is there flow in the pipe 46 toward the supercharging evaporator 58 due to the check valve 46b.

The cooled liquid in the pipe 51 cannot enter the member 18 through check valve 53 and expansion valve 52 because of the high pressure vapor in the member 18, so a pipe 114 is provided which connects to the pipe 51 just ahead of the check valve 53. The pipe 114 extends to the lower end of the member 20 adjacent the connection thereof with the pipe 45. A thermal regulating expansion valve 115111 the pipe 114 expands the cold liquid refrigerant as it enters the member 20. The member 20 now acts as an evaporator, and heat is removed from the air in the bonnet 23. The vapor passing from the member 20 flows through port 40d in the valve 22 and into the return line 43, to be drawn into the cylinder 32 upon the intake stroke of the piston 43.

It is believed clear from the foregoing that my improved mechanism operates efliciently either as a heating or cooling system, and that the conversion from heating to cooling is accomplished by turning a single electrical switch 89.

While it is desirable toutilize outside air partially preheated in the attic space as the main heat source, and to augment this heat source with mild air from a ground air well, it is contemplated, in instances where a ground air well cannot be provided, that the main heating air be drawn directly from outside, and attic air and water be used as the mild heat source for supercharging and defrosting. In such a case, the decreased volume of air drawn from the attic space would allow a higher attic temperature to be maintained, and the attic air utilized in the system would be at a temperature sufficient for defrosting purposes.

In either arrangement the completed air conditioning system utilizes one air conduit circuit comprising ducts 24 and 25 and the bonnet 23 for circulating air through the dwelling area 12. It uses a second air conduit circuit, including the inlet pipe 28 and the discharge pipe 31 for drawing outside air into the dwelling and discharges it outside of the dwelling. The third air duct 60 draws air from the area (either the attic or the ground well), which because of its position relative to the dwelling, keeps air therein at a temperature above the outside temperature during the heating season. In the first instance the second circuit consists of

conduits

28 and 31 which also takes air that is heated from the dwelling, while the conduit 60 of the third air circuit takes mild air from the ground beneath the dwelling. In the situation where r a ground air well cannot be provided, the conduit 28 would take its air directly from outside the dwelling and the attic where it would be drawn in through the conduit 60. In both instances there is one air duct circuit for circulating air through the dwelling area, which during the heating cycle, contains the condenser. There is a second air duct circuit taking outside air through the system and dischargingit to the exterior of the dwelling and this circuit has the evaporator therein to extract heat from the outside air during the heating cycle. There is also a third air conduit circuit which receives its air from the area (attic or air well) which supplies heat to keep the air above the outside air temperature during the heating season. This third circuit also has an evaporator in it where heat is picked up to supply a refrigerant vapor as a supercharge to the compressor.

It is believed that the nature and advantages of the invention appear clearly from the foregoing.

Having thus described my invention, I claim:

1. An air conditioning system for dwellings having an attic area over the dwelling area into which air may be drawn and having abasement area into which air may be drawn from the earth, said system comprisingan air duct circuit for circulating air through the dwelling area from the basement area, a condenser in the basement area and within said air duct circuit, a second air duct circuit taking outside air through the attic area to the basement area and from the basement area to the exteri or of the dwelling, an evaporator in the basement area within said second air duct circuit, a third air duct circuit in the basement area connected to the second air duct circuit to discharge air to the evaporator and having an inlet drawing air from the earth, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator and compress it and discharge it into the con-denser, a second evaporator in said third air duct circuit, a refrigerant carrying pipe leading from said condenser having one branch pipe leading to said first named evaporator and having a second branch pipe leading to the second evaporator, said second evaporator having an outlet pipe leading to the compressor, and the first named branch pipe being in heat exchange relation to the outlet pipe whereby to transfer heat from condensed refrigerant to the evaporated refrigerant in said outlet pipe.

2. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air,

because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, means to return condensed refrigerant to said evaporator, a second evaporator in said third air duct circuit, a refrigerant carrying pipe directing a part of the condensed refrigerant to the second evaporator, said second evaporator having an outlet pipe leading to the compressor, said means including a conduit for refrigerant in contact with said outlet pipe whereby to transfer heat from condensed refrigerant to the evaporated refrigerant in said outlet pipe.

3. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, air cut-off means operable, in response to ice formation on said evaporator, to restrict the flow of air past said evaporator to air in said third air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, means to return condensed refrigerant to said evaporator, a second evaporator in said third air duct circuit, a refrigerant carrying pipe directing a part of the condensed refrigerant to the second evaporator, said second evaporator having an outlet pipe leading to the compressor, said means including a conduit for refrigerant in contact with said outlet pipe whereby to transfer heat from condensed refrigerant to the evaporated refringement in said outlet pipe.

4. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, hecause of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a

I second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, air cut-01f means operable, in response to ice formation on said evaporator, to restrict the flow of air past said evaporator to air in said third air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, means to return condensed refrigerant to said evaporator, a second evaporator in said third air duct circuit, and a refrigerant carrying pipe directing a part of the condensed refrigerant to the second evaporator, said second evaporator havin an outlet pipe leading to the compressor.

5. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, and means to return condensed refrigerant to said evaporator, said means including a conduit in said third air duct circuit operable to transfer heat between the condensed refrigerant and the air in said third air duct circuit.

6. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and r discharge it into the condenser, and means to return condensed refrigerant to said evaporator, said means including a storage vessel for condensed refrigerant having a bottom outlet to said evaporator and a top outlet leading to the compressor, the compressor having its chamber provided with an opening to said outlet uncovered to the compression chamber only at the finish of the in-take stroke of the compressor.

7. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to said con-denser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, and means to return condensed refrigerant to said evaporator, said means including a storage vessel for condensed refrigerant having a bottom outlet to said evaporator and a top outlet leading to the compressor, the compressor having its chamber provided with an opening to said outlet uncovered to the compression chamber only at the finish of the iii-take stroke of the compressor, said outlet having a venturi restriction therein, and the evaporator to compressor connection ineluding a bypass to said restriction provided with a check valve limiting flow through said bypass to the condition when vapor fiow through the venturi restriction drops the pressure in said bypass below the pressure in the evaporator to compressor connection.

8. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, and means to return condensed refrigerant to said evaporator, said means including a storage vessel for condensed refrigerant having a bottom outlet to said evaporator and a top outlet leading to the compressor, the compressor having its chamber provided with an opening to said outlet uncovered to the compression chamber only at the finish of the in-take stroke of the compressor, said means also including an evaporator in said third air duct receiving a part of the condensed refrigerant, and having its discharge connected to said opening to the compression chamber.

9. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to said condenser and evaporator to draw refrigerant vapor from the evaporator, compress said vapor and discharge it into the condenser, means to return condensed refrigerant to said evaporator, temperature sensitive elements responsive one to the evaporator temperature and the other to the air temperature on the upstream side of the evaporator, control means operably connected to said elements to stop the compressor upon increase in temperature difference between the evaporator and the upstream air above a predetermined amount, and an air damper in said second duct upstreamfrom the evaporator o-perably connected to the control means to close said second duct when the compressor is stopped.

10. An air conditioning system for dwellings having therein a dwelling area, and a second area in which air, because of the position of said second area relative to the dwelling, receives heat to keep it at a temperature above outside air temperature, said system comprising an air duct circuit for circulating air through said dwelling area, a second air duct circuit drawing outside air into the dwelling and discharging it outside of the dwelling, a condenser in the first said air duct circuit, an evaporator in the second air duct circuit, a third air duct circuit leading from said second area and discharging into said second air duct circuit, a compressor operatively connected to it into the condenser, means to return condensed refrigerant to said evaporator, a second evaporator in said third air duct circuit, a refrigerant carrying pipe directing a part of the condensed refrigerant to the second evaporator, said second evaporator having an outlet pipe leading to the compressor, said means including a conduit for refrigerant in contact with said outlet pipe whereby to transfer heat from condensed refrigerant to the evaporated refrigerant in said outlet pipe, and a water jacket around References Cited in the file of this patent said outlet pipe having means to direct water into heat 10 2,716,870

exchange relation to said outlet pipe.

UNITED STATES PATENTS Buchanan a. July 12, Ambrose Aug. 18, Clancy June 28, Silvestro Feb. 12, Jones Jan. 19, Gygax June 8, Biehn Sept. 6, Borgerd et al. June 12,