US2474369A - Air circulation control system - Google Patents

Description

June 28, 1949. w. A. RAY

AIR CIRCULATION CONTROL SYSTEM Filed Aug. 19, 1944 "vi 91 5 iff/21A] I Q FM 0 i. 3 ,5 2 0/ 2 lnvcmox WILLIAM A. RAY.

Patented June 28, 1949 2,174,389 AIR CIRCULATION CONTROL SYSTEM William A. Ray, Los Angeles, Calif assignor to General Controls 60., a corporation Application August 19, 1944, Serial No. 550,160

My present invention relates to temperature control systems for houses or other structures, and more particularly to systems wherein circulation of a fluid medium, such as outdoor air, which periodically varies in temperature above and below the temperature of the structure is employed for changing the temperature thereof in a desired sense. An example of such a system is found in the "attic cooler commonly in use in regions where the temperature of the outdoor air becomes considerably lower than that of the house during the night. The "attic cooler comprises means, such as a fan installed in the attic, for withdrawing the warm air from the house and replacing it with cool air from outdoors. The circulation of air is manually started during the evening; time-controlled means usually being provided for stopping the circulation at a predetermined tlme of the morning. This method of control is not very eflective for the reason that the circulation is stopped regardless of prevailing climatic conditions which might make it advantageous to set the time of stopping ahead, or even behind. Thermostatic control of the circulation by means responsive to the temperature of the outdoor air or of the house is also not fully effective since no consideration is then given to the fact that at the particular temperature at which the circulation is stopped there may still be a favorable difference between the indoor and outdoor temperatures. It is thereforean object of this invention to provide, in connection with a system of the general character described above, means for stopping circulation of the medium when its temperature and that of the space influenced thereby become substantially equal.

Another object of the invention is to provide means for stopping the circulation when the temperature of the space starts to change in a sense opposite to that desired.

Another object is to provide means responsive to the difference between the temperature of the medium and that of the space for stopping the circulation when said difference becomes substantially zero.

Other objects and advantages of the invention 3 Claims. (Cl. 98-1) Figure 3 is a front'elevation of a modified form of control device according to the invention.

Referring first to Figs. 1 and 2 of the drawing, the numeral ll indicates a base upon which a bracket I2 is pivotally mounted at l3. Secured by a strap II to the bracket is a mercury switch comprising a glass tube having, fused therein,

contact elements it and containing a globule of mercury l1 adapted to bridge the elements when the bracket is tilted counterclockwise, as"

shown. Indicated at I8 is a pair. of electric service lines which are connected, in series with the mercury switch, to an electric fan It.

Mounted on the lower part of the base II is a temperature responsive device comprising a sealed expansible-contractible metallic bellows 20 containing a thermally expansive fluid. The lefthand end of the bellows is rigidly secured to the base by a strap 2| and its movable right-hand end or head is provided with an extension 22 engageable with an abutment 23 extendin from the front surface of a gear 24 pivotally mounted on the base. The gear 2| meshes with another gear 25 mounted on a pin 26 extending from the base, this pin also supporting a catch arm 21. As is seen in Fig. 2, catch arm 21 and gear 25 are held together, and against a shoulder formed by an enlarged portion 28 of the pin, by a spring washer 29; a friction disk 30, of cork or the like, being interposed between the catch arm and the gear. The catch 21 hasa free fit on the pin; gear 25 preferably fitting tightly, and the pin 26 being freely rotatable on the base. Connected at its opposite ends to gear 25 and to the base is a spiral spring 30 which urges the gear in a counterclockwise direction, as viewed in Fig. 1, so that the abutment 23 of gear it follows the movement of projection 22 of bellows 20 when the same contracts.

Catch arm 21 cooperates with the corner portion 3| of the switch bracket l2, this comer being shown in Fig. l as resting on a shoulder 32 formed on the catch arm adjacent its top. The bracket l2, together with the mercury switch, is biased by gravity in a clockwise direction so that if the catch arm is rotated out of engagement withthe bracket the same is tripped into engagement with a stop' pin 33; the switch then being so tilted that the mercury flows out of contact with the elements It.

In connection with the operation of the control device described above, it will be assumed that the fan is is arranged to circulate outdoor air to the interior of a house and that the temperature responsive device, comprising bellows 20, is within the house (preferably close to some incoming air stream) and responds to the temperature thereof. With the parts in the positions shown in Fig. 1 the system is in operation, as during the a night. As the temperature of the house falls due to the circulation of air, the bellows contracts, with the result that gears 24 and 25 rotate under the force of spring as the abutment 23 follows the movement of the bellows. In this rotation of the gears, the catch arm 21 slips with respect to gear 25 since it is restrained from counterclockwise rotation by the engagement with its shoulder 32 of the corner 3| of the switch bracket. When, normally in the early morning, the temperature of the outdoor air rises to a degree at which it is no longer effective to cool the house (or rises above that of the house) the bellows 25 starts to expand due to rise of house temperature. When this occurs, the gears 24 and 25 are rotated in directions to disengage the catch arm 21 from the switch bracket i2; there being no appreciable impedance to the movement (by its frictional engagement with gear 25) of the catch arm in that direction. When the catch has moved through a distance corresponding to the width of its shoulder 32, the switch bracket trips by gravity (into engagement with stop 33) to effect deenergization of the fan and stoppage of the circulation of air-the cooling system remaining inoperative until the switching means is manually reset," as will be described. As the temperature of the house continues to rise during the day, the catch 21 rotates clockwise until its movement is arrested by engagement of its lower portion with the extension 34 of the switch bracket.

To reinitiate operation of the system,. the handle 35 of the switch bracket is raised; the bracket extension 34 moving catch arm 21 until its .tip 35 is engaged by the corner 3| of the bracket, the catch arm then being in vertical position so that when the bracket is released it rests in the position shown in Fig. 1.

Referring now to the modified form of control devic shown in Fig. 3, the numeral 4| indicates a base whereon is mounted a bracket 42, rockable about a pivot 43, which carries a mercury switch comprising a tube 44 having the usual contact elements 45 and globule of mercury 45. The switch is connected to control supply of energy to an electric fan 41 from service lines 45. Mounted on the lower part of the base is a pair of expansible-contractible bellows 45 and 50, the outer ends of which are rigidly secured to the base by straps 5| and 52; the adjacent movable inner ends or heads of the bellows being attached to opposite ends of a connecting member 52. Bellows 49 is fluidly connected by a capillary tube 54 to a thermal bulb 55, the bellows 55 by tube 55 to another bulb 51. For adlustably biasing the bellows system in either direction there is provided a resilient member 58, the upper end of which is disposed between a pair of pins 59 extending from the connecting member 53. The direction and degree of tension of the resilient member is controlled by rotation of a knob 55 by means of which the lower portion of this member is secured to the base. The bellows 48 and 50 and their associated thermal bulbs and 51 are charged with a thermally expansive fluid which is also compressible or elastic so that no destructive force is set up by simultaneous expansion or contraction of both bellows resulting from. like temperature changes at the bulbs. Rotatably mounted on a pin 5| extending from the base is a catch arm 52, the upper end of which is formed to provide a shoulder 53 upon which the lower corner 54 of switch bracket 42 rests when the switch is in circuit-closing position, as shown. Between the lower end of the catch arm and an extension 55 of the bellowsconnecting member 53 is a lost-motion or flexible connection 55 which may be a piece of cord or fine wire.

The operation of the control apparatus of Fig. 3 will be described in connection with the same type of house-cooling system as was described above in connection with Figs. 1 and 2; it being assumed that bulb 55 is arranged to respond to the temperature of the house, and bulb 51 to that of the outside air. The parts are shown in Fig. 3 in the positions in which they are when the cooling system is in operation and the temperature of the outdoor air is slightly lower than that of th house. I! such diflerence of temperature increases during the night, the extension 55 moves in a right-hand direction so that the catch-arm connection 55 slackens. When, normally toward morning, the temperature of the house approaches that outdoors, the parts will again be in the positions shown in the drawing. As the indoor and outdoor temperatures become substantially the same, the extension 55 moves far enough toward the left to effect, through the then tightened connection 55, disengagement from its shoulder 53 of the switch bracket 42;

the bracket tilting by gravity into engagement with a stop .51 to eiiect deenergization of the fan.

The control device of Fig. 3 is usually arranged to eil'ect stoppage of the circulation when the temperature of the outdoor air is still slightly below that of the house; however, under some circumstances it may be desirable to continue cir culation of air even when its temperature is somewhat above that indoors, as, for example, to provide'ventilation while cooking is in progress. Either of these conditions of control can be met by adjustment of the bias applied to the bellows system by member 55.

To reinitiate night operation of the system, the handle 55 of the switch bracket is raised so that catch arm 52 is tilted clockwise; this arm being biased by gravity to vertical position so that (when temperature conditions are such that the connection 55 is slack) the shoulder 63 of the arm is in position to receive the corner 54 of the switch bracket when the handle is released.

-In the systems described above it is assumed that circulation of the air is controlled by starting and stopping an electric fan; however, it is obvious that similar results could be achieved by opening and closing dampers or the like if other means for circulating the air are available.

The system of this invention has utility in connection with control of circulation of any fluid which normally has a beneficial temperature relation to the space with respect to-which it is circulated, but which at times may vary in temper ature in an undesired sense-as, for example, in a system wherein a liquid is employed for heating a space, circulation of which should be stopped in the event that for some reason the tion of outdoor air to the interior of the house: means for effecting said circulation of air, electrically-operable means for operating said circulation-efiecting means, switching means for controlling said electrically-operable means and biased to circulation-stopping position, means manually movable to a position to set said switching means in circulation-starting position, means responsive to the temperature of the house for so operating said movable meansas to trip the switching means to circulation-stopping posie tion upon rise of house temperature, and means for maintaining said temperature responsive means continuously in operative relation to said movable means so that the switching means is tripped upon any rise of house temperature, said maintaining means including means forming a slip-clutch.

2. In a system for cooling a. house by-circulation of outdoor air to the interior of the house: means for effecting said circulation of air; electrically-operable means for operating said circulation-efiecting means; a switch for controlling said electrically-operable means; stop means, manually settable to active position, for temporarily maintaining said switch in circulationeifecting position against the force of said bias, said stop means being movable in one direction to trip said switch to its biased position; means movable in response to variations of the temperature of the house; means trictionally connecting said temperature-responsive means to said stop means; said temperature-responsive means being capable, upon any rise of temperature of the house, of efiecting through said friction connection movement of said stop means in said one direction to trip said switch; and means for preventing movement of said stop means in an opposite direction while it is maintaining said switch in circulation-effecting position, said triction connection then serving as .a slip-clutch.

3. In a system for cooling a house by circulation of outdoor air to the interior of the house: an

electrictfan for eflecting said circulation; a switch for controlling the operation of said fan; stop means, manually settable to active position, for temporarily maintaining said switch in closed position against the force of said bias, said stop means being movable in one direction to trip said switch to open position; means movable in response to variations of the temperature of the house; means forming a clutch frictionally connecting said temperature-responsive means to said stop means; said temperature-responsive means being capable, upon any rise of housetemperature, of effecting through said clutch movement of said stop means in said one direction to trip ,said switch; and means for preventing movement of said stop means in an opposite direction while it is maintaining said switch in closed position, said clutch then serving to permit movement of said temperature-responsive means relative to the stop means with fall of temperature.

WILLIAM A. RAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 548,456 France Oct. 21, 1922

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