US2245773A - Temperature control system - Google Patents

Description

June 17, 1941.

A. C. GRANT TEMPERATURECONTROL SYSTEM Filed Dec. 7, 1938 inventor Patented June 17, 1941 TEMPERATURE CONTROL SYSTEM Arthur C. Grant, St. Paul, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application December 7, 1938, Serial 'No. 244,405

12 Claims.

The present invention relates to a temperature control system and more particularly to one in which the flow of temperature changing fluid to a temperature changing device is modulated in accordance with a controlling condition.

An object of the present invention is to provide a temperature controlling system employing a temperature changing means supplied with a temperature changing fluid wherein a valve controls the supply of temperature changing fluid to said temperature changing means, the valve being modulated by an actuator in accordance with a desired controlling condition and wherein there is an electromagnetic connection between the actuator and the valve, which electromagnetic connection is released upon the temperature of the space whose temperature is being controlled assuming a predetermined value.

A further object of the present invention is to provide such a system wherein the electromag- 1 netic means is also deenergized when the valve reaches a position so close to a predetermined one as to prevent proper operation of the temperature changing means. r

A further object of the present invention is to provide such a system in which the temperature changing device is a heating means and in which the electromagnetic connection is deenergized when the temperature in the space being heated rises above a-predetermined value.

A further object of this present invention is to provide such a control system in connection with a heating system employing a fluid medium for transferring the heat from the heating means to the space being heated, and wherein the valve is modulated in accordance with the temperature of this fluid medium.

A further object of the present invention is to provide a system such as set forth in the preceding object in which the valve is modulated in accordance with the temperature of the fluid medium returning from the space to the heating means.

A still further object of the present invention is to provide such a system in connection with a gas burning furnace wherein means are provided for releasing the electromagnetic connection when the valve reaches a position such that when the flow of gas therethrough is incapable of maintaining proper combustion.

Other objects of the invention will be apparent from a consideration of the accompanying specification, claims, and drawing.

In the single figure of the drawing, the temperature control system of the present invention is shown in schematic form with the valve portion thereof shown in larger scale than the rest of the elements of the system in order to more clearly indicate the details of construction thereof.

Referring to the drawing, a warm air furnace is generally designated by the reference numeral It. This furnace comprises a furnace proper designated by the reference numeral III which is surrounded by a jacket l2. Located within the furnace proper is a gas burner I3 and a normally constantly burning pilot burner M. The air which is to be heated enters the furnace at a cold air inlet l5 and passes inside of the casing 12 out to a hot air delivery pipe Hi. The delivery pipe I6 is provided with various branch ducts ll (only one of which is shown), each of which ducts leads to a register l8 in a space I!) which is to be heated. Also located in the space I9 adjacent the floor is a'return air register connected with a return air branch pipe 2|, which in turn connects with the main return air duct 22. This a return air duct 22 is connected to the furnace at the cold air inlet l5.

The main burner I3 is supplied with gas by a pipe 25 connected to a gas supply pipe 26, the connection being controlled by a valve 21. The gas before entering the burner passes through a mixing chamber 24 of conventional type, in

tending through the aperture of the partition wall in sliding engagement with the wall of the aperture. The sleeve 8 is provided with the conventional inverted V shaped slots 9 to provide a uniform variation in flow with change in the valve position. Secured to the valve disc 32 by any suitable fastening means is a valve stem 33. A diaphragm 34 is clamped between two washers 35 and.33 by nuts 31 and 38 which are threadedly engaged with the valve stem 33. The outer edge 'of the diaphragm is clamped between the valve casing 21 and a circular plate 39 which is aperhired at 40 to permit the valve stem 33 to extend upwardly therethrough. Supported upon the plate 39 is an inverted cup shaped casing 42. Secured to the top of this casing is a smaller cup shaped casing 43 in which is located a bellows element 45. Enclosing the casings 42 and 43 is an outer casing member 44. Connected to the interior of the casing 43 and extending through casing 43 and casing 44 is a capillary tube 41 which leads to a bulb 46 located in the return air duct 22. The bulb 46 is filled with a suitable volatile fluid and the pressure .of vaporization of this fluid is transmitted to the interior of the housing 43 and consequently to bellows 45.

The bulb and bellows construction J'ust described forms the actuator for the valve, which actuator is employed to modulate the valve in accordance with return air temperature. An electromagnetic connection is provided between the valve and this actuator. Secured to the under side of the upper wall bellows 45 is a plunger 48. This plunger is adapted to bear against a core member 49 of magnetic material which is provided with a number of downwardly extending portions to provide a generally inverted cup shaped configuration. Wound upon the core member 49 is an electromagnetic winding 50. operating with the armature 49 is a core 5| which is longitudinally movable in the cylindrical recess of winding 58. A spring 53 serves to bias the coil and armature construction into engagement with the plunger 48. Upon energization of the winding 50, the solenoid core is drawn up into engagement with the armature 49 and is thereafter movable therewith. Upon the return air temperature rising, the pressure exerted on bellows 45 is increased and the entire assembly comprising plunger 48, core member 49, solenoid core 5|, and valve disc 32 is moved downwardly towards valve closed position.

Secured to core member 49 is a switch blade 55 which is adapted to cooperate with an adjustable contact 56 extending through an insulated block 51 secured in the casing 42. The contact 56 is at the end of a screw 58 so that upon threading the screw in or out, the spacing of the contact from the switch blade 55 may be adjusted.

Provisionis made for securing modulating operation of the valve during power failure. Secured to the lower side of valve disc 32 is a rod 11 which carries an inverted cup-shaped member 18 telescopingly engaging a second cup-shaped member 19 carried by a screw 80. The two cupshaped members 18 and 19 act as guides for a spring 8| supported by the lower cup-shaped member 19. The spring 8| is of limited extensibility and with the screw 80 in the position shown, which is the position for normal operation, the spring 8| does not engage the upper wall of cupshaped member 18. If it is desired to operate the system during a power failure, the screw 80 may be screwed inwardly until the screw head 83 engages a boss 84 of the valve casing. Inthis position, the spring will exert enough force upon the solenoid core 5| to hold it in engagement with the core member 49 even when core member 49 is in its uppermost position.

A thermostat 59 is located in the space l9. This thermostat may be of any suitable construction but is shown for purposes of illustration as comprising a bimetallic element 60 to which is and contact breaking operations of the thermostat. This differential eliminates the disadvantage of the thermostat opening and closing its circuit an excessive number of times when thrla temperature is at approximately the desired va 1.18.

A further thermostatic switch is designated by the reference numeral 65. This thermostatic switch corn-prises a helical bimetallic element 66 which extends into the bonnet of the furnace Ill and which has the end thereof connected to a rod 61 which, in turn, is connected to a switch blade 68. Switch blade 68 is adapted to be moved into and out of engagement with a fixed contact 69. The bimetal element upon being heated servesto rotate rod 61 and consequently switch blade 68 in a clockwise direction. The thermostatic switch 65 is employed as a limit control responsive to bonnet temperature.

Operation The various elements of the system are shown in the position which they assume when the room thermostat is calling for heat but in which the valve has been modulated so nearly to closed position that the switch consisting of switch blade 55 and contact 56 has been opened to cause deenergization of the winding 58. This deenergization of the winding 56 has resuted in valve 32 being moved to closed position by reason of the bias imparted by its own weight and the weight of solenoid core 5|. Particularly in the case'of a gas burner, it is undesirable to continue operation of the burner after the fluid supplied thereto has reached a predetermined minimum. If the gas supplied is reduced below this minimum, the pressure of the gas will be insufilcient to maintain the flame at the burner so that combustion will take place in the mixer 24.

Let it .be assumed 'now that the temperature of the return air falls to a point such that switch blade 55 is moved into engagement with contact 56. An energizing circuit will then be established to the winding 50 as follows: from conductor 10 through switch blade 68, contact 69, conductor 1|, contact 62, contact blade .6|-, bimetal 60, conductor 13, contact 56, switchblade 55, conductor 14, winding 59, and conductor 15. It will be understood that conductors 19 and 15 lead to any suitable. source ofpower (not shown). The establishment of the circuit just traced results in solenoid core 5| being abruptly moved upwardly.

into engagement with core member 49. The contakes place is such that when the core moves upwardly into engagement with the member 49, the valve will pass sufllcient fluid to the gas burner to properly support combustion. It is to be understood, of course, that whenever the valve is throttled towards closed position to a point that switch blade 55 separates from contact 56, the above traced circuit will be interruptedwith the result that the valve moves to closed position as shown in the drawing.

The thermostat 59 will normally be set at a temperature slightly above the optimum temperature. In view of'the fact that the return While the 4 modulation of the valve in accordance with the return air temperature is shown, it is to be understood that the valve could be modulated in accordance with other conditions indicative of the heat loss from the space l9. Thus the valve might well be modulated in accordance with baseboard temperature or even outdoor temperature. In fact, certain features of the invention are applicable to modulation of the valve from any desired condition indicative of the demand for burner operation such as bonnet temperature or, in the case of a hot water boiler, boiler temperature. While the valve is normally maintained in such a position that the right amount of fuel is supplied to the gas burner, it is preferable to insure that if the gas flow is not quite proper, it be supplied in excess of that required in order to insure that an adequate amount of fuel will be supplied to properly heat the space l9. For this reason, continued operation of the gas burner may eventually produce a condition wherein the space temperature rises to the point slightly above that desired at which thermo-- stat 59 is set to operate. When this point is reached, the thermostat opens its contacts and deenergizes the winding 50. Such deenergization of the winding 50 will cause valve 32 to abruptly move to closed position. Thus, with 'JhiS arrangement, the valve is normally modulated to supply heat at a rate equivalent to or slightly above the rate necessary to maintain the space temperature at the desired point and whenever the space temperature does rise :lightly above the desiredvalue, the operation of the burner is abruptly terminated until the space temperature again falls to such value.

It will be noted that the original energizing circuit in addition to including the thermostat 59 and the switch comprising switch blade 55 and contact 56 also included the thermostatic switch 65. This switch is normally maintained closed and is opened only when the bonnet temperature rises to an excessively high point such as may occur during a morning pick-up period or in the case of an extremely sudden temperature drop, such as occasioned by the demand for the heating of rooms not normally heated. In such case, the opening of this switch comprising switch blade 68 and contact 69 will deenergize the winding 50 to cause valve 32 to abruptly move to closed position.

In the event of power failure, the screw 80 is screwed inwardly until the screw head 83 engages the boss 84. In this position of the screw 80, the spring 8| is efiective to urge the core against the core member 49 regardless of the position of the latter ihember. The'valve is then free to be modulated in accordance with return air temperature, the modulation being effected against the action of both springs 53 and 8|. Due to the fact that spring Bl exerts a relatively small force compared with spring 53, the valve will assume substantially the same position for a given return air temperature as when the core 5| is held in engagement with the core member 49 by reason of the energization of coil '50.

It will be seen that I have provided a system wherein the supply of temperature changing fluid to a temperature changing device is modulated in accordance with the demand for operation of, the temperature changing device and wherein upon the space temperature rising above a desired value, upon the valve being movedto a position too close to closed position to properly sustain operation of the temperature changing means, or when the temperature adjacent the temperature changing means rises to an excessively high value, the valve is moved to closed position. This, moreover, is accomplished by means of an extremely simple valve mechanism having a minimum number of parts.

While I have shown a specific embodiment of the invention for purposes of illustration, it ,is to be understood that the invention is limited only by the scope of the appendedclaims.

I claim as my invention:

1. In a temperature control system, temperature changing means, means for supplying a temperature changing fluid to saidtemperature changing means, a valve biased to a predetermined position and controlling the flow of such temperature changing fluid to said temperature changing means, an actuator for said valve, means responsive to a condition influenced by the heat transfer between a room whose temperature is being controlled and the outdoors for causing said actuator to modulate said valve in accordance with the value of said condition, an electromagnet connection between said actuator and ,said valve comprising an electromagnet and armature one of which is connected to said valve and the other of which is positioned by said actuator, and means for deenergizing said electromagnet to release said valve to said predetermined position. when the room temperature assumes a predetermined value.

2. In a temperature control system, temperature changing means, means for supplying a temperature changing fluid to said temperature changing means, a valve biased to closed position and controlling the now of such temperature changing fluid to said temperature chang ing means, an actuator for said valve, means responsive .to a condition indicative of the demand for operation of said temperature changing means for causing said actuator to modulate said valve in accordance with the value of said condition, an electromagnetic connection beture changing means, means for supplying a temperature changing fluid to said temperature changing means, a valve biased to a predetermined position and controlling, the flow of such temperature changing fluid to said temperature changing means, an actuator for said valve, means responsive to a condition influenced by the heat transfer between a room,whose temperature is being controlled and the outdoors for causing said actuator to modulate said valve in accordance with the value of said condition, an electromagnetic connection between said actu ator and said valve comprising an electromagnet and armature one of which is connected to said valve and the other ofiwhich is positioned by said actuator, and means for deenergizing said electromagnet to release said valve to said determined position when the room temperature assumes a predetermined value or when the position to which said valve would be moved by said actuator would be too near to said predetermined position to operate the temperature changing means properly.

4. In a temperature control system, means for heating a fluid medium, means for conveyin the fluid medium from the heating means into heat transferring relation with a room to be heated and back to said heating means, means for supplying a heat producing fluid to said heating means, a valve biased to closed position and controlling the flow of said heat producing fluid to said heating means, an actuator for said valve, means responsive to the temperature of said fluid medium for causing said actuator to modulate said valve in accordance with said temperature, an electromagnetic connection between said actuator and said valve comprising an electromagnet and armature one of which is connected to said valve and the other of which is positioned by said actuator, and means for deenergizing said electromagnet to release said valve to closed position when the room temperature rises above a predetermined value.

5. In a temperature control system, means for heating a fluid medium, means for conveying the fluid medium from the heating means into heat transferring relation with a room to be heated and back to said heating means, means for supplying a heat producing fluid to said heating means, a valve biased to closed position and controlling the flow of said heat producing fluid to said heating means, an actuator for said valve, means responsive to the temperature of the fluid medium returning to said heating means for causing said actuator to modulate said valve in accordance with said temperature, an electromagnetic connection between said actuator and said valve comprising an electromagnet and armature one of which is connected to said valve and the other of which is positioned by said actuator, and means for deenergizing said electromagnet to release said valve to closed position when the room temperature rises above a predetermined value.

6. In a temperature control system, heatin means including a gas burner, means for supplying gas to said burner, a valve biased to closed position and controlling the flow of gas to said burner, an actuator for said valve, means responsive to a condition indicative of the demand for heat for causing said actuator to modulate said valve in accordance with the value of said condition, an electromagnetic connection between said actuator and said valve comprising an electromagnet and armature one of which is connected to said valve and the other of which is positioned by said actuator, and means for deenergizing said electromagnetic connection to 3 release said valve to closed position when the position to which said valve would be moved by said actuator would be too near to closed position to permit a flow of gas sufiicient to support combustion properly.

7. In a temperature control system, a warm air furnace including a fluid fuel burner, means for conveying-the heated air to a room bein heated and for returning the air to the furnace, means for supplying fluid fuel to said burner, an actuator for said valve, means responsive to the temperature of the air returning from the room for causing said actuator to modulate said valve in accordance with said temperature, an electromagnetic connection between said actuator and said valve comprising an electromagnet and armature one of which is connected to said valve and the other of which is positioned by said actuator, and means for deenergizing said electromagnetic connection to release said valve to closed position when the room temperature rises above a predetermined value.

8. In a temperature control system, temperature changing means, means for supplying a temperature changing fluid to said temperature changing means, a valve biased to a predetermined position and controlling the flow of such temperature changing fluid to said temperature changing means, an actuator for said valve, means responsive to a condition influenced by the heat transfer between a room whose temperature is being controlled and the exterior thereof for causing said actuator to modulate said valve in accordance with the value of said condition, a releasable connection between said actuator and said valve for positively connecting said members together, and means for effecting a release of said connection to release said valve to said predetermined position when the room temperature assumes a predetermined value.

9. In a temperature control system-temperature changing means, means for supplying a temperature changing fluid to said temperature changing means, a valve biased to closed position and controlling the flow of such tempera-' ture changing fluid to said temperature changing means, an actuator for said valve, means responsive to a condition. influenced by the heat transfer between the space whose temperature is being controlled and the exterior thereof for causing said actuator to modulate said valve in accordance with the value of said condition, a releasable connection between said actuator and said valve for positively connecting said members together, and means for effecting a release of said connection to releasesaid valve to closed position when the position to which said valve would be moved by said actuator would be too near to closed position to operate the temperature changing means properly.

10. In a temperature control system, temperature changing means, means for supplying a temperature changing fluid to said temperature changing means, a valve biased to a predetermined position and controlling the flow of such temperature changing fluid to said temperature changing means, a mechanical actuator for said valve, means responsive to a first controlling condition for causing said actuator to modulate said valve in accordance with the value of said condition, electromagnetic connecting means between said actuator andsaid valve for positively connecting said members together, a source of electrical energy, means including a switch re-i sponsive to a second condition for electrically connecting said electromagnetic connecting means to said source of electrical energy, and

means for mechanically maintaining said connection between said actuator and valve in the event of the failure of said source of electrical energy.

11-. In a temperature control system, temperature changing means, means for supplying a -temperature changing fluid to said temperature changing means, a valve biased to a predetermined position and controlling the flow of such temperature changing fluid to said temperature changing means, a. non-electric actuator for said valve, means responsive to a first controlling condition for causing said actuator to modulate said valve in accordance with the value of said condition, electromagnetic connecting means between said actuator and said valve, a source of electrical energy. means including a switch responsive to a second condition for electrically connecting said electromagnetic 'connecting means to said source of electrical energy. and means for applying to said valve a force not normally applied thereto for biasing the same into operative connection with said actuator in the event 01' the failure of said source of electrical energy.

12. In a temperature control system, means for heating a fluid medium, means for conveying the fluid medium from the heating means into heat transferring relation with a space to be heated and back to said heating means. means for supplying a heat producing fluid to said heating means, a valve biased to closed position and controlling the flow of said heat producing fluid to said heating means, an actuator for said valve, means responsive to the temperature or said fluid medium for causing said actuator to modulate said valve in accordance with said temperature. an electromagnetic connection between said actuator and said valve comprising an electromagnet and armature one or which is connected to said valve and the other of which is positioned by said actuator, and means for deenergising said electromagnet to release said valve to closed position when the position to which said valve would be moved. by said actuator would be too near to closed position to operate-the heating means properly.

ARTHUR 0. GRANT.

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