US2604090A - Sheetsxsheet i - Google Patents

Description

July 22, 1952 P. s. MARTIN 2,604,090

DRAFT OPERATED COMBUSTION AIR INLET CONTROL.

DEVICE FOR COMBUSTION APPARATUS A 2 SHEETS-SHEET 1 Filed Nov. 5, 1947 4 a0 a a8 i Q0. r r g 40 I 37 4 M W :5: I. .6/ 5 28 '62 I Z9 I v 23 Fl INVENTOR.

PERRY ,5. MAer/A/ ATTOP/Vf/ July 22, 1952 P. s. MARTIN DRAFT OPERATED COMBUSTION AIR INLET CONTROL DEVICE FOR COMBUSTION APPARATUS 2 'SHEETS-SHEET 2 Filed NOV. 5, 1947 I'IIIIA INVENTOR. 'Pieemi M4P77/V 05M 0 M/W- ATTORNEY 3 Z MU 5 AUWH 0 W6 ma 3 ,0, 4/ a/yli w 7 w ,A

Patented July 22, 1952 PARATUSY Perry' 5.

AVIIR'IINLIET Martin, Harrisonbu1-g,"Val

Application November 2,1947, Serial No; 3183;816 I I Myinvention relates to a thermostatically actuated, automatically operating temperature controldevice of the type'especially adapted for-use'zinregulating the supply of combustion air delivere to a solid fuel burning apparatus.

One objector the inventionis to produce an improved temperature control device "of the type setiorth." 1

Temperature control devices-usually iunction by moving afdamper from fully closed to partly, or fully, open position. In order to obtain a fairly accurate control, the damper should. be as light and as free of'friction as possible.

It is therefore a further object of the invention to produce an improved temperaturecontrol device in which the arrangement, mounting. and location of the damper or dampers, are such that the amount of friction present is negligible and in which the dampers are relatively light.-

A still further object is to produce an improved temperature control devicewhich employs a pair of dampers which are so located relativeto each other and to the direction of flow-ofair through the openings controlled by the dampers,so that the dampers are in almost, but not quite, 'balanced condition whereby minimum power will have to be exertedby the thermostat to movethe dampers.

A still further object isto produceian improved temperature control device in which the imbalance-of the dampers is'utilized to cause. the dampers to tend to close, in :windy weather. 1 1

A still further object of the invention "is to produce a simple, inexpensiveand durable temperature control devicezofthe characterset forth.

These and other objects are attainedby my invention as set forth in the .following specification and as shown in the accompanyingdrawings in which:

Fig. .1 is a top plan view of a temperature control device embodying-my invention, the same being shown attached to a portion of the wall of a solid fuel burning stove. I I

Fig. 2 is a vertical section on 1ine II--.II on Fig. 1 with the wall of the stove omitted, andwith the dampers shown closed. v I V Fig. 3 is a horizontalsection on line III-III on Fig.4 is similar to Fig. 2 but with the'dampers shown open. a I

Fig. 5 is a view similar to Fig. 2, illustrating another embodiment of the invention.

Fig. 6 is a fragmentary elevational view looking the direction of lineVI-e-VI on Figs. 2

and I a 3 Claims. '(ol. i2s 29o) Fig. '7 is a fragmentary, sectionalview taken on line VII--VII on Fig.--5.; I \I Fig. 8 is a fragmentary sectionalview taken on line VIII-VIII on Figs.2 and 5. p,

- Fig. 9 is :a perspective view o f 'the damper assembly, looking in thedirection of-line IX- IX onFigs.2and5 I i In both embodiments of theinvention the tam perature control device includes 'a dra ftjtube, connectible to the combustion chamber ot'afsolid fuel burning stove and thermostatically operated dampers for controlling thejlow pfcombustion air through said-tube. ,Thedraft tube, the dang. ers and the casing of the contrqldevice are pref-. erably made of inexpensive and easilyfabricated sheetmetah: g

The draft tube-may have any desired .,.cross' 'sectionalshapeabut', as .shown, it is soiuaie or rectangular, and it y .iormed o'f side ,walls iii-,1 a bottom'wall H, a top-wall I2 andone end wall 13. The other end of the draft tube is unobstructed and is attachable, in any well known manner, to the air inlet of the combustion cham ber of a solid fuel burning stove onlyaportion M of which is shown in Fig.1: I U I I The draft tube provided with an. air met opening lfi formed in .the {top wall 12 and..with an air inletopening 18in the end wall I3 thereof. It willbe noted that the opening 1.6.is in a hori zontal plane While the opening I8 is in.a vertical plane and. that the opening it is smaller than" the opening l3. It will also .benoted'that the damper 20 which closes theopening 16 has asmaller-ar'ea; than the damper which closes the opening it and that the :dampe zfl'moves' to closingiposition against the direction of. the flow of air through the opening it, while the fi'la'mper I8 'moves' to closing position with, .or in the. direction of the flow of the air through the opening I8.- These.

are all important features of the invention and I will hereinafter be ;more fully described.

-The dampers 20 and 2| are carried by. the horizontal and vertical arms Hand 24, respec tively, of a right-angle bracket, which' is best shown in Fig. 9. The arm 23 is provided with a slot 25. (Fig. 9) through whichextends atongue 26 formed on; the upper edge of a vertically disposed wallg2l of a U-shaped bracket the ;.bight portion 28; of which issuitablysecured to the top wall lzof the draft. tube. Theupper; edge of the wall 2.1,--;on' eit-her side of j the tongue 26', in cooperationgwith the tongue-.26 :and ithe slot .25 ..form a knife edge-pivotbearing --.f or the damperv supporting, bracket. In other words the arm 23' of the damper-bracket is mounted; and.

The movement of the dampers to the open 1 position is limited by contact ofthe underside of the arm 23 with the upper edge of the other limb 25 of the U-shaped bracket, as shownin Fig. 4. The damper 20 is secured to the free end of the Whether the dampers close the inlet openings fully, or whether they only partly restrict the flow of air by reducing the clearance between the dampers and the walls 12 and I3 depends on the degree of heat to which the thermostat is subjected.

Conversely, when the thermostat is fully contracted, .whichihappens when the temperature to be controlled falls to a predetermined value, the

knob 4! ceases to press against the upper end of the lever 35 and the dampers automatically revert to' the open position of Fig. 4. It will be notedthat, in opening, the damper moves downwardly, or in the direction of the flow of air through the opening I6 and that, in

' '-0pening,'the'damper 2| moves in a direction oparm 23 by a chain or a link 30 and the damper 2| is secured to the lower end of the arm 24 as shown at 32 in Figs. 2 and 5, or in any other suitable manner.

The dampers are moved from the open position of Fig. 4 to the closed position of Fig. 2, or to any position in between, by pressure applied to the arm 24 by the lower portion 34 of a lever 35, the upper portion 36 of which issecured at 31 to the vertical portion 38 of an angle member the horizontal portion 39 of which is pivoted at 40 in a slot-formed in a vertical wall 42 of the casing of-the thermostat.-

The lever 35 is actuated by a heat responsive element such as a wafer thermostat 46 which is mounted adjacent the fupper portion 36 of the lever. When the thermostat expands, the knob 41 thereof moves to the lleft, 'as shown in the drawings, and bears upon the arm 38 and the upper portion 36 of the lever 35 with a pressure which varies with theheat to which the thermo stat is subjected. When the heat reaches a predetermined value, the pressure exerted will begin to move the arm 35 to the left and will cause it to exert pressure on the arm 24 in a direction partly or wholly to close the damper 2! and, hence, the damper 20. The thermostat 46 is carried by an arm 50 which is pivotally suspended, at 5|, from a wall 52 forming part of the casing. By this means the thermostat can be moved towards or away from the upper portion of the arm 35 to predetermine the extent to which the thermostat must expand before it will actuate the dampers.

The thermostat is adjusted, or moved to the desired position relative to the arm 35 by a. cam 54 which is rotatable by a knob 55 joumalled in a wall of the casing. By turning the knob, the cam 54 will be turned to cause a relatively high, or a relatively low, portion thereof to bear against the portion 59 of the arm 50 to move the thermostat 45 further to the left as shown in the drawings. The arm 50 is so constructed that, in the absence of pressure by the cam 54, the thermostat will be in the position of Fig. 4 in which it exerts no pressure on the lever 35 and the dampers are left free tomove, by gravity, their non-obstructing position. I r 7 a The operation is as follows: 3 As the room temperature rises, the thermostat I 46 expands and exerts pressure on the upper portion 33 of the lever 35. The lever 35 being rigid, and being pivoted at 40, the pressure exerted by the thermostat on its upper portion will move the lower portion 34 thereof, and, hence, the damper 2 I, in a direction to close the opening l8. Movement of the damper 2| horizontally toward the opening l8 causes theda'mper 20 to move upwardly toward the opening l6,'and vice versa.

/ posed to'the'direction of the flow of air through the opening I8. However, and as above pointed out, the area of the damper 2| is greater than the area of the damper 20 so that the damper 23 must be so weighted as to overcome the excess'air pressure which is exerted on ithe damper-12L Further, because the movement 'of'the' damper- 2|, in opening direction, isagainst the static pressure of the air, as wellas against the dynamic pressure of the air flowing in the direction of the opening IS in response to reduced pressure with' in the stove, the movement of both dampers 'wvill' be gradual, rather'than abrupt and, therefore, the operation of the dampers will be free ofclanking and other noises which may be caused by sudden movement or impact of metallic parts.

The same is of course true when the dampers move to closing direction because, then, the damper 20 will be moving against the pressure of the air flowing through the opening I6.

The arrangement of the dampers, whereby'they are almost, but not quite inbalance, leaves very little work for the thermostat; In other Words, a very slight expansion'of the thermostat 'willbe enough to overcome the slight imbalance and the insignificant. friction and inertia present and willmove the dampers accordingly. Therefore, a sensitive thermostat can be'used and a very accurate control of the temperature to be regulated canbehad.

- In blustery weatherythe air tends to flow through the openings l6 and I8 at a more rapid rate. This increases the combustion and increases the negative pressure within the stove thus further accelerating the flow of air through the inlet openings. If this-condition is allowed to prevall'until' the room air is warm enough to cause the thermostat to. close the dampers, there will be a more or less serious temperature override. Therefore, to prevent or minimize such temperature over-ride, it is necessary to close the dampers somewhat before the room temperature has reached the desired maximum value This problem is also solved by making the damper 2| of slightly larger area than the dampor 20 so that the excess air pressure exerted on the outer surface of the damper 2|, as compared with th pressure exerted on'the upper side ofthe damper 20, will tend to, move the dampers toward closing position thus automatically reducing or shutting off the supply of air. Also, while this is taking, or is about to take, place, the thermostat will have begun to expand and while the expansion may not have, as yet, become enough, of its self, to move the dampers to partly or wholly closed position, it will be found that, the/action of the thermostat, assisted by the pressure differential on the dampers, will cause the dampers .to close partly, or wholly, thus reducing or bustion, induced by the increased supply of air prior to the closing of I the dampers will be enoughto bring the room 'temperaturefup ito'ithe desired value with little or no over-ride:

By turnin the cam 54'so'astomovethe theb mostat nearer to-the lever -35,* the amount-ore);- pansion of the thermostat needed to mov e 'the dampers to'closing positionwill-be reduced-and a relatively low-room-temperature will b'e maintained, and vice versa. 1;

While I have described the invention as applied to a solid fuel heatingjstove, it isof course evident that my novel arrangement ofdampers can be used to control th'ep'assage of 'airto, or through, other heat producing apparatus.

In order to prevent, or minimize, over-ride or the opposite effect, in the temperature to be controlled, during Ordinary weather and wind conditions, I enclose the thermostat in an improved casing so arranged that the thermostat is alternately bathed in streams of air of different temperatures, depending on whether the dampers are closed or open so that the thermostat will have anticipatory action and will move the dampers in one direction or the other somewhat before it would have otherwise done so.

As shown, the thermostat is positioned in a compartment 60 defined by the wall 42, front wall 6|, side walls 62, and the top wall 53*. The front wall and side walls 62 extend downwardly to the draft tube to form an extension of the compartment 60. The lower end of the com partment 60 is open and the sid walls 62 of this compartment are provided with apertures 63. The top wall (i3 of the compartment is provided with one or more openings 64 and the wall 42 is provided with upper and lower openings 65 which lead to an intermediate compartment 66 formed between the wall 42 and a wall 68. The wall 68 cooperates with a bottom wall 10, a vertical wall 12 and the side walls 62 to form a second compartment 14 which is provided with one or more top openings 16 and which communicates through an opening 18 with the compartments 66 and 6B. When the control device is in position, the wall 12 and the compartment 14 are im mediately adjacent the wall 14 of the stove and are subjected to the high temperature prevailing in the vicinity of thestove. The compartment 60 in which the thermostat is located is separated from the compartment I4 by the intermediate dead air space or compartment 66. Therefore, the thermostat is effectively insulated from the heat of the stove. On the contrary, the thermostat, except as hereinafter explained, is constantly bathed by the air of the room the temperature of which is to be controlled, the room air being free to circulate through the compartment 60.

However, when the dampers are open, the air flowing through the openings l6 and I8 tends to entrain air from the lower portion of the compartment S0 and produces reduced pressure in the compartment 60. This causes room air to flow through the top openings 64, 65, I6 and 18, downwardly over the thermostat. Since the air flowing through the openings 16 and 78 comes from the vicinity of the stove and is hotter than the room air entering through the opening 64, the thermostat will be subjected to air having a mean temperature higher than the temperature of the air in the rest of the room. The thermostatwill thuslbegin'to close the dampers a little before -thero'om air te'mperaturel has reached the desired value."'By' this meansfthe heat which will continue tobe'generated even afterithe air supply is reduced orcutbifgwill bring the room temperature to the desiredvaluei This prevents the rise-of the temperature to-be controlled much above the-desired value;

- Conversely, when the dampers are closed', room air-will flow through the open, "lower' end of the compartment-15B and through theofoenings -63, upwardly through the 'compartme'nt {6D and out through i the top openings; By this means fthe thermostatis 'subjected to the temperature of the room, exclusively, andwill therefore permit the dampers to open as soon as the room temperature falls to a given value. The room air thus bathing the thermostat shields it from any direct heat from the stove which would otherwise expand the thermostat and thus delay the opening of the dampers and will thus permit the room temperature to fall below said given minimum value.

In Fig. 5 I have shown another embodiment of the invention in which I include a second thermostat the function of which is to close the dampers i in response to excessive heat which might result from a failure of the thermostat 46 to operate as intended.

The secondary or safety thermostat illustrated is formed of a bimetallic element 88, disposed in the compartment Id, and carried by a bracket 82 secured to the wall 12. The element 80 is connected by means of an adjustment screw 84 to a lever 88 which is pivoted at 40 to the wall 68 and which is secured at 37 to the upper portion 3% of the damper actuating lever 35. As the bimetallic element is heated, the upper arm thereof moves in counterclock-wise direction thus pivotin the lever 88 and causing the pendant portion thereof to press against the upper portion of the lever 35 to move the dampers to closing direction, and vice versa.

,By turning the screw so as to cause it to move downwardly relative to the lever 88, the play between the element 89 and the head of the screw is reduced. Therefore, a relatively small expansion of the bimetallic element will move the dampers in closing direction and, vice versa.

inlet opening in a first wall of said casing and a second air inlet opening in a second wall of said casing, said second opening being spaced from said first opening and said walls being in planes which intersect to form an angle which is less than degrees, a first damper for closing said first opening, a second damper for closing said second opening, an angle member having a first arm and a second arm, means connecting the end of said first arm to said first damper, means connecting the end of said second arm to said second damper, and supporting means pivotally supporting said angle member at point adjacent the junctions of said arms, whereby arcuate movement of said arms about said last mentioned means will bodily move said dampers jointly toward, and away from, their respective openings, said angle member and said supporting means being located wholly outside of said casing.

2. The structure recited in claim 1 in which the dampers and the arms of the angle member are so arranged and weighted that, in the absence 01' other influences, said first damper will move, by gravity, to a non-obstructing position with reference to said first opening and will move the second damper to a non-obstructing position with reference to the second opening. 7 q

3. The structure recited in claim 1 in which the first damper moves toward the non-obstructing position in the direction of the flow of air through said first opening and the second damper moves toward the non-obstructing position against the direction of the flow of air through the second opening, and in which the surface area of the first damper is less than the surface area of the second damper, the weight difierential being substantially balanced by the greater air resistance of the second damper.

PERRY S. MARTIN.

8 REFERENCES CITED j file ofthis -patent: I k V um'rrinisTATEs PATENTS Number, Name Date 123,252 Eldridge Jan. 30, 1872 945,831; Westphal Jan. 11, 1910' 1,995,209 Kuenhold Mar. 19, 1935 2,061,587 Morris e Nov. 24, 1936 2,151,512 Hagen Mar. 21, 1939 2,226,815 Haines, Dec. 31, 1940 2,406,088' Martin Aug. 20, 1946 I FOREIGN PATENTS Number Country Date 51,569, .Germany Apr. 19, 1890 49,568

, Sweden 1 Aug. 22, 1917

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