US2256840A - Furnace regulator - Google Patents

Description

Sept. 23, 1941. HAINES I 2 256,840

FURNACE REGULATOR Filed Aug. 19, 1938 .l W Jwhn E. Haines attorney Patented Sept. 23, 1941 FURNACE REGULATOR John Haines, Chicago, IlL, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn a corporation of Delaware Application August 19, 1338, Serial No. 225,825 1 Claim. (01. 236-9) My invention relates to temperature regulators and is more particularly applicable to control of coal fired furnaces and boilers by automatic regulation of the draft and check dampers normally I forming part of such equipment.

The object of my invention is to provide a compact, eiiicient, and inexpensive temperature regulator adapted for controlling the draft through coal fired heaters.

Another object is to provide a device of this general nature which dispenses with cumbersome weights and similar arrangements and utilizes adjustable resilient devices for securing automatic control of a furnace or boiler.

Another object is the provision of a damper regulator for controlling a coal fired heater which is adjustable by a space thermostat for maintaining a. relatively high heater temperature when the thermostat is calling for heat and for maintaining a relatively low heater temperature when the space thermostat is satisfied, thereby preventing the fire from going out during such periods; Y

Another object is the provision of a spring loaded temperature regulator responsive to heater conditions having space temperature responsive mechanism for adjusting the spring loading.

Another object is the provision in a device of the character described of independent high and low limit temperature adjustments.

Other objects and advantages of my invention will become apparent from the detailed specification following, the invention residing in the improved construction, arrangement, and combination of parts.

The single figure of the drawing is a crosssectional view of a preferred form of my invention installed in a furnace damper control system.

Referring to the drawing, I have shown my improved regulator generally at I as comprising a substantially cylindrical casing 2 havinga bottom plate 3 suitably secured thereto by means of screws or the like 4.- Formed integrally'with the bottom plate 3 is a nipple portion 5 which may be engaged in screw-threaded relation with a suitable fitting in the upper part of a boiler. Engaged in screw-threaded relationship with the interior of the nipple portion 5 is a fitting 6 to which is securedthe lower of a plurality of expansible cells 1. The expansible cells 'I are comprised of diaphragm members sealed together so as to be fiuid tight, the cells communicating with each other and with a sealed tube 8 extending portion 5. The cells I and tube 3 may be filled witha temperature responsive medium and collectively form a heat responsive element in the manner well known in the art. Supported on the upper surface of the uppermost of the cells I is a plate or disc H which may be suitably,

fastened to the expansible cells and which has integrally formed therewith'a lug 12 to which is pivoted a. lever lit by means 01' a pivot pin M. The lever I3 extends through an opening ii in one side wall of the casing 2 and through an opening ill in the opposite side wall and is pivotedv at I6 to a fixed support I! extending integrally from the side wall of the casing 2.

Numeral 20 designates generally a heat motor which is-disposed in the upper part of the casing 2 and comprisesa pair of expansible cells 2| and 22. The cells 2| and 22 are each formed of diaphragms suitably secured together at their edges so as to be fluid tight and are also filled with a temperature responsive medium adapted to expand upon the application of heat thereto.

The upper diaphragm of the cell 2| has a central downwardly from the fitting 6 within the nipple 65 embossment or convex portion 23 which engages and interfits with a corresponding depression in the top of the casing 2 for the taining the cell 2| in position. The lower diaphragm of the cell 22 has a similar embossment or convex portion 24 which engages and interfits with av corresponding depression formed in a disc or plate 25 hearing against the bottom of cell 22. Interposed between the cells 2| and 22 is a grid or framework 26 comprising plates 21 and 28 which bear against the cells 2i and 22, respectively, and are held in spaced relation by spacing members 29 and 30. Supported by the spacing members 29 and 30 is a heat resistant element 3| upon which is wound a coil 32 of electrical resistance wire forming a heater. The ends of the resistance wire 32 are connected to a pair of electricalconductors 33' and 34.

Integrally formed on the plate 25 is a projecting portion 31 which engages "in a suitablev depression in the end of a lever 40.. The lever 43 is pivoted at II to the support I! and alsoex tends through the opening IS in the side wall of the casing 2. Connected between the left ends of the levers, l3 and 40 is a coil spring 42, the

' upper end of which engages a member 43 engaged on a screw 44 extending through the end of the lever 40 and locked in position by means of a lock nut 45. Clockwise movement of the lever 40 about its pivot is limited by a screw 46 extending through a bracket 41 formed integralpurpose of rely withthe casing 2, the screw 45 being locked in position by means of a lock nut 45.

As previously pointed out, my improved re lator is primarily adapted for controlling the dampers of a coal flred furnace or boiler. In the system which I have shown, numeral 50 designates a boiler which may be of conventional other end of which The right of which is connected to.

end of the lever I5 is also connected to the chain 53 and the chain may be passed over pulleys 55, 55, 56, and 51 mounted in pulley blocks suitably disposed with respect to the installation so that the chain can be easily moved for operating the dampers.

The device may be controlled from a space or room thermostat 55 which may preferably be of a conventional type comprising a bimetal element 6| arranged to actuate a. movable switch arm 52 cooperating with a flxed electrical contact 53. The electrical conductor 33 previously described is connected to the fixed electrical contact 53 and the conductor 34 may lead to a suitable source of external power, not shown. Another electrical conductor 54 also leading to the external source oi power is connected to the thermostat. 50.

With the parts in the-position shown, the room or space thermostat ll is calling for heat and a circuit energising the electrical heating resistance 32. is completed through the conductor 54,

the thermostat, conductor 3!, resistance.32, and conductor 54. Heat from the resistance 32 has caused expansion of the fluid contained in cells 2| and 22 causing the lever M to be moved in a clockwise direction until it has engaged the stop screw 45. As can be seen from the drawing, this clockwise movement of lever 50 has added a certain amount of tension to the spring 42, which has caused movement of lever IS in a clockwise direction so as to move the chain 53 in a directionto open the draft damper 5| as shown and close the check damper 52. By reason of these positions of the dampers, the rate of combustion will be increased in the furnace for supplying heat to the spaces wherein the thermostat 50 is located. As the boiler temperature increases above the desired value the fluid within the cells I will expand correspondingly, tending to move the lever II in a counterclockwise direction against the force of spring l2. This will cause movement of the draft damper towards closed position and the check damper towards open position for reducing th rate of combustion. Conversely, upon a decrease in boiler temperature, the cells I will contract under the action of spring 42, which will cause the dampers to be shifted in a direction to increase the rate ofcombustion. In this manner, the regulator will act to maintain the boiler water at the 'desired temperature. The temperature maintained in the boiler when the room thermostat is calling for heat may be conveniently adjusted by adjusting the position of the screw 45 in the bracket 51. By unscrewing the screw 48, the heat motor will cause lever an to be moved further in a clockwise direction tending to increase the tension of spring 42 which raises the temperature setting of the regulator. Conversely, by screwing down on screw 45, the tension on spring 42 due to expansion of the heat motor is decreased which lowers the temperature setting.

Should now the thermostat 60 become satisfled indicating that no further heating is necessary for the time being, the heater 32 will be deenergized causing the cells comprising the heat motor 20 to collapse. This will immediately permit lever 40 to rotate in a counter-clockwise direction, releasing some of the tension in spring 42 which will cause leverl3 to be rotated in a counter-clockwise direction so as to close the draft damper 5i and open the check 52. By reason of the positions the dampers are now in, the furnace 'flre will diminish and the pressure within the cells 'I will drop accordingly. When the Y boiler temperature has dropped to some low value,'which may be for example it is desirable that the dampers be open slightly in order to prevent the flre from becoming completely extinguished. When the pressure within the cells I of my device has dropped to a value corresponding to such a temperature of the boiler, the lever I! will have been moved clockwise under the. combined action of the spring 42 and cells I to slightly open the draft damper 5| and to move the check damper 52 to closed position. The boiler responsive device comprising the cells I will now control the temperature of the boiler and maintain it substantially at 100v in this manner, or at some other suitable value which may be determined by adjustment of the screw 44. In order to adjust the low limit of boiler temperature to be maintained, for example, to lower it, the screw 44 may be unscrewed tending to reduc the amount of tension in the spring 42. Obviously, the result will be that the pressure in the cells I will have to fall to a lower value before it will be unbalanced by the reduced amount of tension in the spring 42 so as to cause the lever l3 to be moved in a direction to open the draft damper 5| and close the check 52.

From the foregoing, it is apparent that I have provided a compact and sturdily constructed device for controlling the temperature of a furnace wholly automatically in a manner such that overheating is prevented and additionally the fir is prevented from becoming extinguished. The boiler responsive device controls the boiler temperature and prevents it from exceeding a limiting relatively high value when the space thermostat is calling for heat and controls the boiler temperature maintaining it at a relatively low value when the space thermostat is not calling for heat. This is accomplished as I have described by automatically changing the adjust- .ment, or in other words, the loading of the spring 42. A further advantage of my invention is that I have provided separate adjustments as I have described for adjusting the high and low limit temperatures of the boiler which are to be maintained. This provides an important convenience inasmuch as in different installations wherein this type of boiler is used or where different temdisclosed and described in detail a representative preferred form of my invention. There are other forms and embodimentswhlch my invention may take and many changes and variations will occur to those skilled in the art but which are within the scope of my invention as manifested in the representative form herein disclosed. The boundaries of my invention are, therefore, to be determined only by the scope of the appended claim.

I claim as my invention:

In a damper regulator system for operating a combustion regulating damper for a solid fuel fired space heater, in combination, a base mem her, a first diaphragm means carried on said base member and responsive to a pressure varying with the temperature of the heater, means piv'- oted on said base member and actuated by said first diaphragm means for positioning said damper, biasing means including a spring for .upon heat demand from said second temperature responsive means, and separate means for adjusting said biasing means so as to maintain a predetermined low heater temperature when said second temperature is satisfied for thereby causing the regulator to maintain the fire slightlv active at such times.

JOHN E. HAINES.

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