US1949640A - Air conditioning apparatus - Google Patents

Description

March 6, 1934. s. M. ANDERSON AIR CONDITIONING APPARATUS Filed March 25, 1932 GSheetS-Sheet l INVENTOR \fam 412.! M. fine/eme y )MFW 51W ATTORNEY ra Hear March 6, 1934. s, M, ANDERSON 1,949,640

AIR CONDITIONING APPARATUS Filed March 25, 1952 6 Sheets-Sheet 3 Elf/71785? INVENTOR \Sam M M- 6 74015017 ATTORNEY March 6, 1934. s. M. ANDERSON AIR CONDITIONING APPARATUS Filed Marci. 25, 1952 6 Sheets-Sheet 4 PI/ P l ii A 1%? INVENTOR Samuel M Fraser-we BY M PM ATTORNEY March 6, 1934. s. M. ANDERSON AIR CONDITIONING APPARATUS Filed March 25, 1932 6 Sheets-Sheet 5.

INVENTOR Sam ve M qndwo z ATTORNEY S. M. ANDERSON AIR CONDITIONING APPARATUS March 6, 1934.

6 Sheets-Sheet 6 Filed March 25, 1932 Y mm m4 m D m I. i

Patented Mar. 6, 1934 UNITED STATES 1,949,640 AIR .conmrromc APPARATUS Samuel M. Anderson, Sharon, Mass, assignor to B. F. Sturtevant Company, Hyde Park, Mass a corporation of Massachusetts Application March 25, 1932, Serial No. 601,155

8 Claims.

This invention relates to the conditioning of air for passenger vehicles and relates more particularly to the conditioning of air circulated through railway cars. I I

It is now becoming well known that human comfort requires that the air within an enclosure should be not only circulated to provide suflicient ventilation, but should in winter be warmed, with moisture added to maintain the proper relative humidity, and in summer should be cooled, and moisture extracted from it to overcome the excessive humidity which is usually present.

While the conditioning of air for motion picture theaters, hotel, oifice and industrial buildings has been developed to a high degree in recent years, the air conditioning for vehicles, and particularly railways cars, has been more or less neglected, due,- perhaps, to the peculiar problems involved and the many difficulties present. Among the difficulties which present themselves are the lack of space in a railway car which already of necessity has had to accommodate the maximum of equipment in the minimum of space, the excessive refrigeration equipment which would have to be carried if the ordinary method of conditioning buildings were followed, the changing temperature conditions through which a railway car must pass, the costof the equipment, and other difliculties.

The treatment of air for comfort in summer always requires the cooling of air, and, in most instances, both the cooling of the air and the reduction of its moisture vapor content. This is ordinarily accomplished by refrigeration. Perhaps the greatest objection railway companies make of the present system of air conditioning has been the excessive refrigeration equipment required in summer. Not only is there a tremencles, having duplicate dehydration plants, auto-' dous mass and bulk of equipment required for the production of artificial refrigeration or the storage of ice, but the operating expense has been great.

An object of this invention is to condition the the air supplied to passenger vehicles without ,resort to refrigeration.

Another object of the invention is to condition the air supplied to passenger vehicles with a minimum of apparatus and expense.

Another object of the invention is to provide suitable apparatus for dehydrating and cooling the air supplied to passenger vehicles.

Another object of the invention is to provide in an air conditioning system for passenger vehicles, duplicate dehydration plants, one of which may be used while the other is being dried.

Another object of the invention is to provide in an air conditioning system for passenger vehimatic controls 'for placing one dehydration plant out of service and the other into operation.

- Other objects of the invention will be apparent from the drawings and the following description. The air conditioning system, according to this invention, comprises, in brief, a dehydration plant containing silica gel, calcium chloride, aluminum -which cooled water is passed. The temperature of the dehydrated air is reduced by passing it through the cooling chamber so that its dry bulb temperature is approximately that of the coils, the dew point remaining the same. The partially cooled air then passes into a spray chamber with a low dew point, a low wet bulb temperature, and a higher dry bulb temperature, and upon contacting with the .spray of cooled water, the dry bulb and wet bulb temperatures become approximately the same, thedry bulb temperature dropping to substantially the wet bulb temperature. The spray water assumes a temperature corresponding to the wet bulb temperature of the air. Cooled water from a cooling tower is circulated through the cooling coils in the cooling chamber. With this arrangement, the heated summer air may be effectively cooled without resort to refrigeration by use of the dehydration material and the use of the cooling tower for cooling the .water which lowers the temperature of thedehydrated air. 7

When a dehydration chamber containing hydroscopic material suchas silica gel approaches a point of saturation, it becomes necessaryto place it out of service and to dry it out'and to place in service fresh silica gel, the water con-- tent of which islow. In ordinary installations, it is, of course, possible to physically remove one silica gel bed, for example, from an air conditioning unit and to replace it by another one, the replaced bed being dried out by application of heat.

In passenger vehicles, such as'railway cars, it is ,bed may be physically removed and replaced.

Due to this reason and other reasons, such as lack '01 space, and the difficulty of physically removing and replacing the silica gel beds, the ordinary application of dehydration plants to railway car conditioning are not practical.

This invention provides conditioning systems whereby duplicate silica gel or other suitable mechanical dehydration beds are employed, one bed being dried out while the other is in operation removing moisture from the air to be conditioned.

In one embodiment of the invention, duplicate silica gel beds are arranged side by side in a dehydration chamber and are both associated with the same cooling and spray chambers. A damper is arranged to by-pass the air around the inactive unit and to pass the air through the active unit. When the active dehydration bed has been in service a period of time suiilcient for it to approach a predetermined point of saturation, the air is by-passed around it through the ior merly inactive unit, which is placed on an active status, and heat is applied to the formerly active unit to dry it out while the unit now active is absorbing moisture. x

In another embodiment of the invention, duplicate air conditioning units are located in opposite ends of a vehicle, the air of which is to be conditinned. Each conditioning unit comprises a dehydration chamber containing silica gel, for example, a cooling chamber, a spray chamber, and an outside air intake. A central water supply supplies water for the spray and cooling chambers. A central heat supply supplies heat for drying out the silica gel bed which is inactive. Only one of the air conditioning units is actively conditioning the air at any one time, the other unit serving as a dummy unit to aid in the circulation of the air supplied by the other unit. The air from the active unit passes through the inactive unit, is by-passed around the air conditioning equipment of the inactive unit, and circulated by the fan or blower of the inactive unit back to the intake side of the active unit. With this arrangement, no ducts are used, the air being circulated down along one side of the car by the active unit and being returned along the other side of the car by the inactive unit, the conditioned air penetrating the passenger space due to the displacement of heated air by the heavier conditioned air. When the active dehydration bed approaches the point of normal saturation, it is automatically cut out of service, the water in its associated spray and cooling chambers is shut off, and heat is turned on to dry the dehydration bed. The other dehydration bed which has been first dried out and then cooled is automatically cut into service. The water for its associated spray and cooling chambers is turned on. The air to be conditioned is routed through the bed now active and around the unit now being dried out. w

The invention will now be explained with reference to the drawings, of which:

Fig. 1 is a partial side view, with a portion removed, of a railway car equipped according to this invention;

Fig. 2 is a plan view, with a portion removed, of the air conditioning unit shown by Fig. 1;

Fig. 3 is a side view partially in section of Fig. 2;

Fig. 4 is a top view, with a portion removed, of the air washer unit of Fig. 1;

Fig. 5 is a plan view of the cooling chamber unit utilized.

Fig. 6 is a diagrammatic view of a complete system, according to this invention, showing one cooling tower for cooling the water that is circulated through both the spray chamber and the cooling chamber;

Fig. '1 is a diagrammatic view of an embodiment of the invention in which duplicate air conditioning units are provided at each end of a railway car, the intention being that one system functions as anair conditioning system while the dehydration material in the other 'system is being dried out;

Fig. 8 is a plan view, with a portion removed, of each of the air conditioning systems of Fig. '7, showing how the system which is being dried out can be used for returning recirculated air to the other system for conditioning;

Fig. 9a is a diagrammatic plan view of a railway car, with the top removed, illustrating the physi cal arrangement of the two air conditioning systems of Fig. '7

Fig. 9b is a side view of the apparatus shown by Fig. 8;

Fig. 10 is a diagrammatic view showing automatic controls for the system shown by Figs. 2, 3, and 6;

Fig. 11 is a diagrammatic view showing automatic controls for the systems shown by Figs. 7 and 8;

Fig. 12 is a diagrammatic view of a solenoid mechanism suitable for closing the valves and dampers of Figs. 10 and 11, and

Fig. 13 is a diagrammatic view of a solenoid mechanism suitable for controlling the air flow in Figs. 6 and 7.

Referring now to Figs. 1 to 5 inclusive, the physical arrangement of one embodiment of the invention will be explained. The air conditioning unit 15, mounted in the upper half deck of the car, as shown by Fig. 1-, comprises a recirculated air intake 16, an outside air intake 17, a filter 18 in the recirculated air intake, a damper 19 which acts to close off the recirculated air intake 16, a mixing chamber which is divided into two portions 20 and 21, the two portions being divided by a damper 22, the position of which is controlled by the solenoid Q. The portion 21 of the mixing chamber provides an air passage which connects with the silica gel chamber 23. the mixing chamber 20 leading to the silica gel chamber 24. There are provided two identical silica gel chambers in order that one may be utilized by conditioning air while the other is being dried out. The air which passes through the active silica gel chamber, passes next through the cooling chamber 25, the details of which are shown by Fig. 5, is partially cooled and then passes through the spray chamber 26 where it may be saturated. The air passes from the spray chamber into the fan unit 2'7 which is connected by means of duct 28 to a distribution duct 29, extending longitudinally of the car. This distribution duct 29 may be provided with a plurality of spaced openings through which the conditioned air is supplied into the car.

The cooling chamber 25 comprises a series of coils of pipe 30 which are provided with extending surfaces 31 for expediting heat transfer. The spray chamber shown by Fig. 4 is seen to comprise a plurality of nozzles 61 which are supplied With spray water, as will be explained later. The air enters the spray chamber in the' direction opposed to the movement of the spray and passes through the filter 32 where it is relieved of entrained moisture.

Operation of the embodiment of the invention illustrated by Figs. 1 to 5 inclusive will now be described with reference to the diagrammatic drawing shown by Fig. 6. Recirculated and outside air enters the mixing chamber 20, passes into one of the silica gel chambers 23 or 24, where its moisture contentis reduced by the absorbent characteristics of the silica gel, which material has the property of absorbing an amount of moisture equal to several times its own weight. The temperature of the air increases'during absorption, due to the fact that the latent heat of the moisture is given ofi as sensible heat. The wet bulb temperature of the air, however, is considerably reduced due to the removal of moisture. The heated air next passes over the coils 30 in the cooling chamber 25 where its dry bulb temperature is reduced to approximately that of the coils. The air next passes into the spray chamber 26 where it saturates its dry bulb temperature, drop'- dry and wet bulb temperature and is delivered into the space occupied by the passengers in a. railway car.

- The cooling chamber 25 and the spray chamber 26 are provided with water which is cooled by evaporation in the cooling tower 33. This cooling tower is constructed similar to the washer cham ber shown by Fig. 4 except that there is no necessity for a filter and a fan 34 driven by the motor 35 is associated with the cooling tower for drawing air through the spray produced by the no:- zles 36. The cooled water from the cooling tower passes through the pipe 38 under the action of the pump 39, then passes through a' dividedpath,

through the pipe 40 to supply the spray cham-,

ber 26, when the level of the water therein is. low, and through the pipe 41 to supply continuously the cooling chamber 25. The spray chamber 26 is provided with a sump 42 in which the spray water collects and from which the water from the sump 42 is circulated through the pipe 43, the pump 44, and back'to the spray nozzles 64. When the level of the water in the sump 42 gets low, the fioat 45 acts to open the valve 46 to permit water from the pipe 38 to flow into the spray chamberpiping. The water from the cooling chamber 25 is returned through the pipe 4'? to the spray heads 36 where the water is again sprayed. The distribution of the cooled water is so arranged that the heated air is progressively cooled. For example, the portion of the piping nearest the silica gel chamber 23 is supplied with warmer water than the other end of the chamber. a

The duplicate silica gel beds 23 and 24 are so arranged that one is active in extracting moisture from the air to be conditioned while the other is having its moisture content removed and is being placed in position to be substituted for the active unit when the active unit has absorbed a predetermined amount of moisture. The transfer of the dehydration beds and the operation of their'necessary associated apparatus is controlled by a timing device which will now be explained in connection with Figs. 6 and 10 of the drawings. Suppose, for example, that the silica gel bed 24 is active in absorbing moisture from the air while the bed 23 is being placed in condition f3! operation in its turn. The solenoid Q holds the damper 22 in position to close off the passage of air to the bed 23 and to permit the passage of the air to the bed'24. The inactive dehydration bed 23 is first supplied with heat through the coils 48 to drive out its contained moisture'and after the moisture has been dried out, is supplied with cooling water through the coils 49 which cools the heated bed. The heat is controlled through the electrically operated valve M and the cooling water by the electrically operated valve N. After the bed 24 has been in service for a predetermined period of time, the solenoid Q is operated automatically to open the air passage to the dehydratien bed 23 and to close ofi the flow of air through the dehydration bed 24: When this is done, the electrically operated valve 0 opens to supply heat to the coils 48 in the bed 24. After a predetermined period of time, the valve 0 is closed automatically and the valve P is opened automatically to supply cooling water from the cooling tower 50 through the coils 49 in the dehydration bed 24 to cool the heated bed. The operation of the automatic controls will now be explained with reference to Fig. 10. An electrical clock mechanism comprises the field coils 130 and the rotor 131.. The rotor 131 revolves a disc 132 at a constant speed as is usual in electric clock movements. In contact with the disc 132 is the clutch member 133, the position of which is, with ref-, erence to the periphery of the disc, governed by adjustment of the clutch lever 134, movable along the scale 135. The clutch member 133 drives, ,through the shaft 136, a bevel gear 137, which is meshed with another bevel gear 138, to which is attached the contact arm 139. The contact arm 139 is rotated at a speed depending upon the position of the clutch member 133 on the disc 132, this speed of rotation being controlled by the clutch member 134 along the scale 135.

Arranged in the travel of the contact arm 139 and in a position to be contacted with the arm during portions of its travel are the contact segments 140, 141, 142, 143 and 144. The contact segments 140 and 141 are associated with-the electrically operated valves M and N respectively controlling the heat supply and cooling water supply to the dehydration bed 23. The contact segments 143 and 144 are heat supply valve 0 and cooling water supply valve P respectively in the dehydration bed 24. The contact segment 142 is associated with the solenoid Q which controls the position of the shutter 22. The segment 140 is arranged to be in contact with the arm 139 during the first quarter of its travel. The segment 141 is in contact with the arm 139 during the second quarter of its travel. The segment 143 is in contact with the arm during the third quarter .of its travel. The segment 144 is the fourth quarter of its travel. The segment 142 is in contact with the arm during the first half of its travel.

The portions of the clutch mechanism and the gearing of the clock mechanism are adjusted so that a period of time is required to rotate the arm 139 in one half of its travel, during which period of time one dehydration bed would absorb associated with the a predetermined amount of moisture suificient to require it to be cut out of service and the other bed cut into service. Purely for example. let us say that the physical proportions of the system and the temperature and humidity conditions through which the railway car is passing require that one bed be active for two hours, that it is at the end of two hours, out out of service, the other bed cut into service, each bed remaining in servicetwo hours and out of service two hours. Then again purely for illustration, let us assume that one hour is required to dry out the wet bed by application of heat and another hour'is required to cool the heated bed. Thus,

while one bed is actively absorbing moisture from the air to be conditioned, the other bed is being dried out and cooled. The control apparatus shown by Fig. 10 is set up for the purposeof illustration on the above assumptions. The bed 24 is actively absorbing moisture from the air, while the contact arm 139 is moving through the first half of its travel, it requiring two hours for the arm to move through the first half of its travel, and, likewise, requiring two hours for the .arm to move through the second half of its travel. During the first hour of movement, the contact arm 139 closes an electrical circuit including the power supply, the segment 140, and the electrically controlled valve M. This valve M is held open, permitting the uppply of heat to the coils 48 in the bed 23 for one hour. At the end of one hour, the arm 139 has left the segment 140, thus causing the valve M to be closed and the supply of heat to the bed 23 shut oil, and the arm 139 makes contact with segment 141 for the second hour, thus closing an electrical circuit through arm 139, segment 141, and power supply, to hold open the electrically operated valve N which supplies cooling water from the cooling tower 50 to the heated bed 23. During the two hour period in which the bed 23 is inactive and the bed 24 is active, the contact arm 139 is in contact with the segment 142, thus closing an electrical circuit through the solenoid Q and power supply to energize the solenoid to maintain the shutter 22 in a position to close off the air through the bed 23 and to permit air to pass through the bed 24.

At the end of the second hour of operation, the contact arm 139 leaves the segments 141 and 142 and enters contact with the segment 143. The solenoid Q is de-energized and the shutter 22 is placed by action of a restoring spring (see Fig. 13) to close off the flow of air through the bed 24 to permit the flow of air through the bed 23. The valve N, which has been supplying cooling water to the bed 23, is closed. The bed 23 is now in condition to absorb moisture from the air which is now permitted to pass through it. The arm 139, in contact with the segment 143, closes the circuit of the electrically operated valve 0 which suppliesheat to the coils 48 in the now inactive bed 24. At the end of one hour the arm 139 leaves the segment 143 and contacts with the segment 144, the valve 0 is closed to shut off the heat, and the valve P is opened to supply cooling water from the cooling tower 50 to the cooling coils 49 of the bed 24. At the end of the two hour period, during which the bed 24 has been in service, the contact arm passes from the contact segment 144 to de-energize the valve P to shut off the cooling water to the coils 49 of the bed 24, and the arm again enters into contact with the segments 140 and 142 which now place bed 24 out of service and bed 23 again into service. This cycle is continued, one bed, as has previously been explained, serving to absorb moisture from the air to be conditioned, while the other bed is being dried by heat and then cooled. The clutch mechanism serves to vary .the period of time required for the rotation of the arm 139 and thus gives a control which may be operated when changing humidity and temperature conditions are encountered, as when the car passes from a region where rain is falling into a region of dry desert country. 1

In the embodiment above described the dehydration beds are arranged in side by side relationship. It is realized that in some railway cars the space available for conditioning equipment may be too limited for side by side arrangement of the dehydration beds, so provision is made in those instances for the installation of air conditioning equipment in each end of a passenger car, as illustrated diagrammatically by Figs. '7 and 8. As shown by Figs. '7 and 8, another embodiment of the invention is illustrated in which provision is made in each end of a car for separate air conditioning systems, one system serving to condition the air while the silica gel in the other system is being dried out. The system in which the silica gel is being dried out, however, serves to assist in the circulation of the cooled air projected by the active system. This arrangement provides a ductless system, the conditioned air being expelled into the car at one end in the space above the passengers, it passing down along one side of the car at high velocity and being returned by the inactive air conditioning system along the other side of the car to the intake side of the active system. Obviously, such an arrangement contemplates the recirculation of air and only a portion of the conditioned air is taken from the outside. Referring first to Fig. 8, the air conditioning unit there shown comprises a recirculating air inlet 100 50, an outside air intake 51, provided with'damper 52, a single silica gel bed 53, a cooling chamber 54, a spray chamber 55, a fan or blower unit 57, a discharge duct 58, a by-pass duct 59, a damper 60 which acts to close off the by-pass duct 59 when the unit is active and to closeofi the air through the conditioning chambers when the unit is inactive. When the unit is active, that is, the dehydration unit, is extracting moisture from the air, the damper 60 is adjusted to close ofi the by-pass duct 59, as shown by the full lines. The direction of air flow is then that indicated by the continuous line arrows, the air passing first over the silica gel bed 53, then'th'rough the cooling chamber 54, then through the spray chamber 55, and being discharged through the duct 58 into the railway car into the space above that occupied by the passengers and in the direction down along one side of the car. While one of the air conditioning units is operating in this manner, the silica gel bed of the other, or inactive, unit is being dried out. This inactive unit then acts as an air circulation assistant to the active unit as will be explained now. The damper 52 in the outside air intake is closed and the damper 60 is adjusted to close ofi the silica gel bed 53. The fan or blower unit 57 then draws air through the intake 50 and passes it through the by-pass duct 59 and dis-" charges it through the discharge duct 58 in the railway car. The two oppositely opposed units are so arranged that the discharge end of one is the intake end of the other. Thus, while one unit is supplying cool air down along one side of the car, the other unit assists in pulling the cooled air down along that side of the car, and thenreturning it down along the other side of the car downto the intake air side of the unit which is at the moment supplying conditioned air to the car.

Fig. '7 illustrates diagrammatically the arrangement of the apparatus associated with the two units shown by Figs. 9a and 9b, and Fig. 11 illustrates diagrammatically automatic control apparatus for converting the units from active to inactive status. The two air conditioning units ,62 and 63 are those shown by Figs. 9a and 9b, one

' unit, or inactive unit, to circulate and return air supplied by the active unit. Assuming now that the unit 621s active while the unit 63 is inactive, the automaticallycontrolled valve A maintains the cooling water to the spray chamber and the cooling-chamber 54 of the active unit on; the automatically controlled pump C keeps the coolingwater through the spray chamber 55 circulating; and the electrically operated valve J keeps heat circulating through the silica gel bed 53 of the inactive unit to dry out same.

After the silica gel bed 53 has been dried out, the valve J is closed to shut off thesupply of heat and the valves F and H are opened to permit cooling water from the cooling tower 200 to be piped through the coils of the pipe which formerly supplied heat to the bed. The electrically controlled solenoid R1 in the active unit 62 maintains the damper in a position to permit the air to pass through the air conditioning chambers 53, 54, and 55, and to close off the by-pass duct 59. A similar solenoid R, in the inactive air conditioning unit 63, maintains its damper 60 in a position to shut off the air through the air" conditioning chambers and to permit the air to pass through the by-pass duct 59. The electrically operated valves F and H are closed to prevent the supply of cooling water to the cooling and spray chambers of the inactive unit. Likewise, the electrically operated valves E, G, and I, associated with the active unit 62, are closed to prevent the supply of heat and cooling water to the dehydration bed of that conditioning unit. Furthermore, the electrically operated solenoid K, associated with the active unit 62, maintains the damper 52 in the outside air intake 51 open. A similar electrically operated solenoid L maintains the damper in the outside air intake of the inactive unit 63 closed.

Obviously, while the inactive silica gel beds are being dried out by the application of heat, the moisture driven ofi should not be permitted to enter the air stream passing the active beds. Each silica gel bed has been shown equipped with a conventional duct and damper which serve to permit the moisture driven off from the inactive bed, under reactivation, to be. vented to the atmosphere, while preventing the air passing through the active bed from being so vented. These conventional ducts are shown as 51a and 51b in the apparatus'of Fig. 1, and 510 and 51d in the apparatus of Fig. 8. Likewise, the dampers are illustrated as 52a and 52b of the apparatus of Figs. 1 and 2, and as 520 and 52d of the apparatus of Fig. 8.

The operation of the electrically operated valves and solenoids of Fig. 7' will now be described with reference to Fig. 11. An electrical clock mechanism, similar to that described in connection with Fig. 10, is provided to rotate the contact arm 201 in circular travel. On the same assumption as described in connection with Figs. 6 and 10, the clock drive is so arranged that the arm 201 is rotated throughout its complete travel from beginning to end in four hours. In the first half of its travel, requiring two hours, it closes contacts to maintain the air conditioning unit 62 in an active status and the air conditioning unit 63 in an inactive status. During the next half of its travel, .requiring two hours, the air conditioning unit 62 is rendered inactive and the unit 63' active by closure of electrical contacts.

During the first half of its travel the arm 201 is in contact with the segment 202 and closes a circuit including the power supply, the solenoid R1, and the operating mechanism of the valve A, motor C, and the solenoid K. Thesolenoid R1 is energized and maintains the damper 60 (see Fig; 8) in a position to permit the passage of air through the air conditioning chambers 53, 54, and 55, and to close oil" the by-pass duct 59. The pump C is operated to supply spray water to the spray chamber of the active unit. The valve A is opened to let'the cooling tower 203 supply cooling water to the cooling chamber 54 and to the spray chamber 55 of the active unit. The solenoid K is energized to permit outside air to be drawn in through the outside air intake 51 of the unit 62. All of the abovesolenoids, valves, and motors are. continuously energized throughout the two hour period during which the active air conditioning unit 62 is active. During this first two hour period, the contact arm 201, during the first hour of its travel, is also in contact with the segment 204 and completes an electrical circuit, including the power supply and the valve J to open this valve to permit heat to be supplied to the dehydration bed 53 of the inactive unit 63. At the end of the first hour, the contact arm leaves the segment 204 and makes contact with the segment 205 through which the power supply energizes the valves H and F. The valve J is first closed by the contact arm leaving the segment 204 so that heat to the pipes 206 is discontinued. The pipes 206 are connected to the coils 207 and the dehydration bed 53. The valves H and F, on being opened, supply cooling water from the cooling tower 200 through the pipes 206 to the coils 207 to cool the bed 53 which was formerly heated by the heat supply.

At the end of the second hour of travel of the contact arm, it leaves both the segments 205 and 202; the valves H and F are opened, the solenoid R1 is de-energized, the motor C is disconnected, the valve A is .opened, and the solenoid K is de- 115 energized, causing the damper in the outside air intake 51 of the unit 62 to close. This places the formerly active unit 62 out of service. At the same time the am 201 enters into contact with the segment 208 and the segment 209 and energizes the solenoid L which closes, with the damper 60, the by-pass duct 59 of the formerly inactive and now active unit 63, and permits the air to pass through the air conditioning chambers 53, 54, and 55 of this unit. The pump D is started up to circulate spray water through the spray chamber 55 of the unit 63. The valve B is opened to supply cooling water to the spray chamber and cooling chamber of the unit 63. The solenoid L is energized to permit air to pass from the no outside air intake to the unit 63. All of these controls are actuated for two hours while the unit 63 is active. The arm 201 closes circuits through the segment 209 for one hour to open the valve I to supply heat through the pipes 206 to the coils 207 of the dehydration bed 53 of the formerly active and now inactive unit 62. At the beginning of the third hour of travel of the arm, it leaves the segment 209 and makes contact with the segment 210 and closes the valve I and opens 149 the valves E and G to permit cooling water from the cooling tower 200 to be supplied to the pipes 206 to cool the dehydration bed 53 of the unit 62, thus placing it in condition for service when the unit 62 is cut into service and the unit 63 cut out of service at the end of the fourth hour.

Fig. 12 illustrates diagrammatically a solenoid and its associated valve. The solenoids M, N, O, and P of Fig. 10, and A, B, E, F, G, H, I, and J of Fig. 11 may be designed'to close their valves as will now be described. -When electrical current is supplied to the coil 163, it moves its coil 164 against the compression of the restoring spring 165" to move the piston 166 away from its seat in the valve 167, thus opening the valve. When the solenoid is de-energized, the restoring spring moves the plunger 164 to seat the'piston 166, thus closing the valve.

Fig. 13 illustrates diagrammatically the construction of a solenoid for performing the functions '01 the solenoid Q of Fig. 6 and R and R1 of Fig. 7. When the coil of the solenoid is deenergized, its plunger. remains in a neutral position by action of the restoring spring 176. The damper 1'77 has one end attached to the gear segment 173 which is engaged by a rack attached to the plunger. When the solenoid is energized by an electrical current flowing in one direction, the plunger is moved in one direction against the actionof the restoring spring 176 to move the damper 177 in one of the positions indicated by the dotted lines, thus closing off an air passage to one set of silica gel beds with which it is associated. When the solenoid is energized in the reverse direction, the plunger moves to its other extreme position, moving the damper 177 to a position shown by the other in the dotted lines to close ofi the air passage to the other silica gel bed with which the solenoid is associated.

Whereas one or more embodiments of the invention have been described for the purpose of illustration it should be understood that many modifications and departures may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. An air conditioning system comprising a dehydration chamber having duplicate beds of hygroscopic material, a cooling chamber, a spray chamber, a cooling tower for cooling water supplied to said spray and cooling chambers, means for passing a current of air through said chambers, means for rendering one of said beds inactive when it has absorbed a given amount of moisture from the air, means for heating the dehydration material used in the inactive bed, and means for cooling the heated dehydration material in said inactive bed after it has given up its excess moisture content.

2. An air conditioning system comprising a dehydration chamber having duplicate beds of hygroscopic material, a cooling chamber, a spray chamber, means for passing a current of air through said chambers, a cooling tower for cooling the water supplied to said spray and cooling chambers, means for rendering one of said beds inactive when it has absorbed a given amount of moisture from the air, means for heating the dehydration material in said inactive bed for removing excess moisture therefrom, a cooler for cooling the heated dehydration material in the inactive bed after its excess moisture content has been removed, and a cooling tower for cooling water supplied to said cooler.

3. An air conditioning system comprising a dehydration chamber having duplicate beds of hygroscopic material, a cooling chamber, a spray chamber, a cooling tower for cooling the water supplied to said cooling chamber and spray chamber, means for passing a current of air through said chambers, means for by-passing the air around one of said beds, means for heating the by-passed bed to cool same, and means for cooling the by-passed bed after it has been dried.

4. An air conditioning system comprising a dehydration chamber having duplicate beds 01 hygroscopic material, a cooling chamber, a spray chamber, means for passing a current of air through said chambers, means for by-passing the air around one of said beds, a cooling tower, means for circulating water through said cooling tower and said spray and cooling chambers, means for heating the by-passed bed to dry same, another cooling tower, and means for circulating water through said last mentioned cooling tower and the by-passed bed after it has been dried.

5. An air conditioning system comprisinga dehydration chamber having duplicate beds of hygroscopic material, a cooling chamber, a spray chamber, a fan for passing a current of air through said chambers, means for by-passing air around one of said beds, a cooling tower, a pump for circulating water through said tower and said spray and cooling chambers, means for heating the by-passed bed, another cooling tower, means for passing water through said last mentionedcooling tower and saidby-passed bed after it has been dried, and automatic means for controlling said heating and cooling means.

6. An air conditioning system comprising a pair of air conditioning units, one of which is active while the other is inactive, and each comprising a dehydration chamber, a cooling chamber, a spray chamber, a fan for passing a current of air to be conditioned through said chambers, a bypass duct around said chambers, a damper adapted to close ofi the entrance to the chambers or the by-pass duct, means for supplying cooling water to the spray chamber and cooling chamber of the active unit, and means for removing excess moisture from the dehydration material in the inactive unit.

7. An air conditioning system comprising a pair of air conditioning units, one of which is active while the other is inactive, and each comprising a dehydration chamber, a cooling cham her, a spray chamber, a fan for passing a current of air to be conditioned through said chambers, a by-pass duct around said chambers, a damper adapted to close oiT the entrance to the chambers or the by-pass duct, means for supplying cooling water to the spray chamber and cooling chamber of the active unit, means for heating the dehydration material in the inactive unit to dry same, and means for cooling the heated material after it has been dried.

8. An air conditioning system comprising a pair of air conditioning units, one of which is active while the other is inactive and each comprising a dehydration chamber, a cooling chamher, a spray chamber, afan for passing a current of air to be conditioned through said chambers, a by-pass duct around said chambers, a damper adapted to close ofi the entrance to the chambers or the by-pass duct, a cooling tower for supplying water to the spray chambers and cooling chambers of both units, a heat supply common to the dehydration chambers of both units, and means for placing the dampers to close ofi the by-pass duct in the active unit and to cldse ofi the entrance to the chambers of the inactive unit,

dehydration chamber of the inactive unit, and

later to supply cooling water to the heated dehydration chamber.

SAMUEL M. ANDERSON.

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