US2401553A - Control means for draft regulators - Google Patents

Description

June 4, 1946. M, w REW 2,401,553

CONTROL MEANS FOR DRAFT REGULATORS Filed June 50, 1943 2 Sheets-Sheet l INVENTOR. ffb/PE/S 1M CREW I4 W I Patented June 4, 1946 CONTROL DIEANS FOR DRAFT REGULATORS Morris W. Crew, Cleveland, Ohio, assignor to The Hotstream Heater Company, Cleveland, Ohio,

a corporation of Ohio Application June 30, 1943, Serial No. 492,840

3 Claims. (01. 236-45) This invention relates to the control of the draft in the operation of magazine feed stoves or other forms af solid fuel fired furnaces, boilers or space heating equipment.

One object of the invention is to provide an improved draft controller or regulator which is thermostatically controlled in such manner as to automatically limit the rate of combustion and the stack temperature and thus prevent overheating or unnecessary fuel loss.

Another object is to provide an improved thei mostatically controlled draft regulator capable of adjustment to meet any desired temperature conditions, within reasonable limits.

Still another object is to provide a combined draft regulator and controller in which all parts, including the control parts, may be assembled and sold as a complete unit ready for insertion in or attachment to the usual stove pipe connection to the stack.

A further object is to provile a draft control hereinafter. i

In the drawings, which represent one typical embodiment of the invention,

Fig. 1 is a front elevation, showing only a portlton of the stove to which the regulating unit is connected;

Fig. 2 is a side elevation, from the left in Fig. 1.;

Fig. 3 is a sectional elevation on the line 3-3, Fig.

Fig. 4 is a detail sectional elevation on the line 4-4, Fig. 5;

Fig. 5 is a detail sectional plan view on the line 5--5, Fig. 4;

Fig. 6 is a sectional elevation on the 1ine 6--5, Fig. 2, showing the flutter closed; and

Fig. '7 is a similar view, showing the flutter open.

In the drawings It represents conventionally the top portion of any suitable furnace, boiler or stove, preferably fired by coal or other solid fuel, with which the draft regulating or control unit of the present invention may be used. For example, it may be a magazine feed stove of the general form shown in Patent No. 2,255,527, granted September 9, 1941, to Sam P. Locke, although other forms of stove may be employed. In the arrangement shown the products'of combustion or flue gases leave the stove by way of an opening in its upper portion to whichis connected the pipe or conduit II for conducting such ases to the chimney or stack (not shown) or to the outer atmosphere. The regulating or control unit of the present invention is attached to or forms a part of the said conduit.

Said unit, in the arrangement sh'own, includes a stove pipe T 12 havin a running section [3 and a lateral section 14 providing three open ended arms a, b, 0, designed for connection oftwo of them tothe stove and stack respectively, with the third open to atmosphere to provide check draft where desirable or necessary.

In the third arm referred to, here marked. c, is located a draft regulator of suitable form consisting of a disc or plate for flutter 15, mounted to pivot or swing at 1-6 in a, thimblelike frame I! and provided with a counterweight l 8. The flutter of course oscillates back and forth between the dotted line position and the full line position against stop Ila, Fig. 6, to balance out fluctuations and varying draft pull from the chimney or stack. The pipe and the particular draft regulator used with any stove will be chosen or selected of the proper siZe and the counterweight l8 will be of the proper calibrated weight to produce the requisite-draft for the desired maximum rating and efliciency, Which in the case of a stove of the type shown may be assumed to require a draft of, say, .04 inch. The counterweight is thus carefully calibrated at the factory to produce that draft, and in operation at maximum output the stove will produce an attendant stack temperature of 850 to 900 F.

The present invention provides means by which the draft automatically may be reduced when desirable,such as during mild weather or when for any reason the stove might continue to operate at maximum output when that is undesirable.

As shown, the control unit includes a thermostatic element, such as a bimetallic strip or member 19, one end of which is fastened to a member 28 pivoted at 2] on a bracket 22, and the other end of which carries an arm 23 pinned at 24 to 1 a rod 25 sliding through and guided in an openture below normal in the space to be heated, such as the room containing the stove. The parts then occupy the positions shown in Fig. 6, with the bimetallic strip holding the rod 25 away from the closed flutter J5. When the fire is started in the stove combustion and draft increase untilthe, stove is operating at maximum output with the desired draft of .04 inch. Heat transfer from the stove to the space :to be heated is rapid. The temperature of the fiue gases and stack reaches 850 to 900 F. and the temperature in the thermostat chamber em slightly lesser value, it being understood, however, that at all times there is a definite relation betweenthe temperatures of the flue gases and in chamber 3!. However, at first and until the room temperature comes up to normal, say 72 F., the temperature in chamber 3| does not rise sufficiently to move the end of rod 25 into the zone of movement of flutter I5.

During the initial period, while the room temperature is rising, the flutter moves back and forth, either quickly, to counteract the effects of gusts, due to back draft, or slowly to. balance out gradual fluctuations in draft pull, thus tending to maintain the desirable maximum stack draft of .04 inch.

When, finally, theroom temperature reaches normal, say 72 F., the rate of absorption of heat by the space to be heated from the exposed heated parts, including the stove jacket, the T IZand thermostat casing 21, etc., has been so reduced that the temperature of both the flue gases and in chamber 3| rises, with the, result of flexing the bimetallic strip I9 until it reaches the position of Fig. 7, with the end of rod 25 Within the zone of movement of the flutter. If, at the time, the flutter is closed, rod 25 will engage it and move it to and hold it in the position of Fig. 7,

whereas if it is already open, rod 25 will merely hold it there. In either case the check draft opening is open, air flow through the fuel bed is reduced and held to a low value, the combus-- tion rate is reduced and sooner or later the stove and stack temperatures are reduced below that attendant upon operation at maxmum rating, to-

wit, 850 to 900? F. Thus, after. the stove has been, operated at maximum. output for a period sufficient, to bring the space temperature up to the desired normal value, it, is thereafter operated with thermostatic control to maintain normal space temperature, without overheating and avoiding unnecessary waste offuel.

- Means may be provided for adjusting the parts to secure and maintain any desired normal space temperature. In the arrangement shown, this means takes the form of a screw 32 threaded into the bracket 22 and having swiveled connection at 33 to the member 20 to which; the lower end of the strip I9 is attached. The head 34 of the screw is exposed on the outside of the casing 21 for manual adjustment. Stops 35, 36 limit the amount of adjustment in bothdirections. As the screw is adjusted to the right, Fig. 6, thenormal space temperature will be increased, as will.

be readily understood.

Means is also provided for manually and releasably locking the flutter in its full open position. This comprises a hand lever 31 pivoted in a bracket 38 on the thimble l1, and having two positions, shown in Figs. 6 and 4 respectively. Fig. 6 is the normal position, when, the lever. is ineffective and flutter I is permitted to have full and unrestricted operation, as before. de-

scribed. Fig. 4 illustrates the locking position 7 of the lever in which its inner arm has engaged the shutter and holds it open. The check draft opening is now wide open and ultimately thestack draft may be reduced to as low as .005 inch. This lever is used when the stove is banked at night and low draft is desirable. It does away with any necessity of adjusting the air intake at the bottom of the stove.

Suitable means may be provided for releasably locking the hand lever in either of the two positions to which it may be adjusted, such as a small teat 39 piuiched out of the metal of the lever and adapted to engage either of two depressions 4:0 in the supporting bracket for said lever.

Since all parts of the mechanism, including the flutter and its thimble and the thermostatic device and its housing, are relatively permanently attached to the pipe T It, the controlling or regulating device here involved may be, assembled as a complete unit on the bench, at the factoryand so sold and shipped for use. stated, the pipe and flutter sizes are predetermined and the weight and location of the, counterweight are calibrated for the particularv size and style of, stove or heating device with which the control unit is to be used, so as to produce the desired stack draft, say .04 inch more or less, required for maximum efficiency and output.

When the unit is installed in, the original setting up of the stove, the bimetallic element is adjusted to a permanent setting by the user, by a series of trials, until the stove produces and main tains the desired normal room or space'temperature. I justing screw 32 inwardly or outwardly to set the angle or position of the bimetallic strip and thus. determine the amount of movement of arm 23 and rod 25 required before rod 25 exerts a controlling effect upon the flutter I5. While any desirable bimetallic. element may be employed, I have used one which begins to travel at 200 F. and which reaches its maximum travel at possibly 800 or 900 of temperature within the T H. When the parts are so adjusted, if the stove is serving a comparatively small space that'may be satisfactorily heated by utilizing onlya portion of the maximum output of the stove, satisfactory heating may be accomplished by adjusting the screw 31 all the way in, which carries the rod 25 closer to thefiutter and permits it to be opened when the stove temperature reaches. 400 to 500 of temperature. When a larger space is being heated thescrew is adjusted all the way out, permitting the stove to operate at maximum output until the normal temperature of 72 is reached, after which thethermostat takes over control and prevents the possibility of the. stove continuing to operate at maximum output and either overheating the room space or unnec essarily wasting fuel.

What I claim is:

1. As an article of manufacture, a.se1f-=contained draft controller adapted for insertion into a stove stack pipe, comprising a pipe T having threev arms, two for connection to the stove and stack respectively, a flutter mounted for swinging motion in the third arm, a housing mounted, on said T closely adjacent to said third arm, a

thermostatic element enclosed within said hous extending through the walls of said housing and,

third arm and movable into and out of the path As before,

This is accomplished by moving the ad- 7 of movement of the flutter, and a manually operatable releasable looking lever for said flutter movably mounted on the third T arm and having two positions in one of which the flutter is free for full motion and. in the other of which said lever engages the flutter and holds it in fully open position, and means for maintaining said lever in either of its two positions.

2. As an article of manufacture, a self-contained draft controller, comprising a pipe T having upper and lower end arms and a middle arm, the lower end arm being connectable to a stove or the like and the upper end arm being connectable to the stack pipe for said stove or the like, a flutter mounted for swinging movement in said middle arm, a chambered housing mounted on the lower end arm exteriorly thereof and in planar contact therewith, the chamber of said housing having no direct communication with such lower end arm, thermostatic means mounted within the chamber of said housing and sensitive to variations in the temperature of the flue gases passing through the pipe T, and means mounted within said middle arm for movement into and out of the path of movement of the flutter, said last named means being operatively connected with said thermostatic means for operation thereby.

3. As an article of manufacture, a self-contained draft controller, comprising a pipe T having two end arms and a middle arm, one end arm being connectable to a stove or the like and the other end arm being connectable to the stack pipe for said stove or the like, a flutter mounted for swinging movement in said middle :11 a housing carried by one of said arms exteriorly thereof, thermostatic means pivotally mounted in said housing and extending into said third arm, a push rod in said third arm adjustably connected to said thermostatic means for movemerit into and out of the path of movement of the flutter, and means connected to said thermostatic means and extending to the outside of the housing for adjusting said thermostatic means about its pivot to vary the range of temperature to which said thermostatic means is effectively responsive.

MORRIS W. CREW.

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