US2538190A - Barometric damper - Google Patents

Description

Jan. 16, 1951 M. W. CREW BAROMETRIC DAMPER Filed Aug. 29, 1945 IN V EN TOR.

.MORR/S I/L C/Pfl V Patented Jan. 16, 1951 BAROMETRIC DAMPER Morris W. Crew, Milwaukee, Wis., assignor to Perfex Corporation, Milwaukee, Wis., a corporation of Wisconsin Application August 29, 1945, Serial No. 613,347

8 Claims.

It has become common to provide furnaces with barometric dampers which maintain constant draft in the take-off flues. These dampers usually consist of a vane which is pivoted offcenter and which is provided with a biasing weight, thereby responding to the difierence in pressure between the flue and atmosphere. As this pressure difference or draft increases, the vane moves inwardly for permitting air to enter the flue, thereby tending to maintain the draft constant.

It has been found that dampersof this type usually work satisfactorily when new, but gradually become inoperative over a long period of time. The reason for this is that the bearings become dirty or rusty, thus requiring a substantial force in order to move the damper blade. In order for the damper to maintain a fairly uniform draft it must be movable by a very small force. Thus when the bearings become rusty or dirty the damper remains stationary, even though the draft may change considerably.

The primary object of this invention is to provide a barometric or pressure operated damper which is not subject to loss of efficiency due to age. This result is obtained by completely elimi- I mating the usual bearing type pivots and mounting the damper blade on spring 'hinges which flex to permit movement of the damper b1ade.

A further object of the invention is to provide an arrangement in which the damper blade is located between the spring hinges and stack so as to protect the spring hinges from the products of combustion.

A further object of the invention is to provide an arrangement in which the spring hinges carry the weight of the damper blade in tension.

Other objects of the invention will appear from the following description and the appended claims.

For a full disclosure of the invention, reference is made to the following detailed description and to the accompanying drawings in which,

Fig. 1 is a front elevation ,of a barometric damper embodying the invention;

Fig. 2 is a side sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view showing the damper in closed position; and

Fig. 4 is a view similar to Fig. 3 showing the damper in open position Referring to the drawings, reference character I indicates a damper frame.This frame is formed with an opening 2 which receives a damper blade 3. As shown in Fig. 2, the inner 2 edges of the frame are turned inwardly as at 4 to, provide for mounting the damper frame on a thimble (not shown), which in turn is mounted to a stack or flue (not shown). Extending inwardly from the damper frame is a bracket 5. This bracket may be formed integral with the frame or may be a separate piece spot-welded to the frame as shown. Attached to this'bracket is a spring hinge 6. In the embodiment of the in- Vention illustrated, the spring hinge is secured to the bracket by screws 1. As shown in Fig. 3, thesescrews extend through holes in the bracket and spring hinge into threaded engagement with a cross member 8. Located on the opposite side of the damper frame is a similar bracket 9 which supports the upper end of a spring hinge Ill and which is also attached to the cross member 8. The lower ends of the spring hinges are secured to the damper frame as shown in Figs. 3 and 4. The lower end of the spring hinge 6 is shown as spaced from the damper blade 3 by a spacer ll, screws l2 passing through this spacer and through holes at the bottom of the spring hinge. These screws threadedly engage an arcuate member [3 which extends upwardly adjacent the spring hinge. The lower end of the spring hinge H] is fastened to the damper blade in this same manner and an arcuate member [4 is located adjacent this spring hinge.

The damper blade is shown as being biased to closed position by means of a weight I5 which is threadedly mounted on a stud 16 attached to the damper blade. Preferably a spring washer IT is attached to the nut and engages the stud so as to prevent unintentional rotation of the weight.

It will be apparent that the Weight l5 serves to bias the damper toward closed position and that the combined weight of the damper blade and its biasing weight is carried by the springhinges in tension. Due to the spring hinges being located off-center with respect to the damper blade, a differential in pressure across the blade causes rotation of the damper. Thus as the furnace draft increases, the difference in pressure causes the damper to rotate clockwise, as seen in Figs.-2, 3, and 4. As shown in Fig. 4, the flexure of the spring hinges is controlled by the arcuate members l3 and I4. These arcuate members limit the maximum. curvature of the spring hing-es and thus prevent these hinges from being stressed beyond their elastic limit. In other words, these arcuate members serve to spread the flexing of the spring hinges over their entire length instead of permitting the spring to yield only at its weakest or most highly stressed point.

From the foregoing description it will be apparent that the present invention provides a damper construction in which the spring hinges are protected from products of combustion and also in which the spring hinges carry the damper and biasing weight in tension. This arrangement, in which the spring hinges carry the weight of the dampenand biasing weight in tension, permits the hinges to carry their load in the most favorable manner.

While a single embodiment of the invention." has been shown, it will be apparent that ,numer-.

.. blade, and a pair of spring hinges, one adjacent ous changes may be made without departing from the spirit and scope of the invention. It is desired therefore to be limited only by the scope of the appended claims.

What is claimed is:

1. In a damper constructionja frame having" an opening, a damper blade for the o.pening, a.

cross member extending from side to side of the frame across said opening, and-apair of spring hinges, one adjacent each end of the cross mem- "ber, each spring hinge having its upper end attached to-the cross member and its lower end attached to the damper blade whereby the Weight of the damper blade is carried by the spring hinges in tension.

2. In a damper construction, a frame having an opening, a damper bladefor the opening, a cross member extending from side to side of the frame across said openingand a pair of spring hinges, one adjacent each end of the cross member, each spring hinge having its upper end attached to the cross member and its lower-end attached to the damper blade whereby the weight of the damper blade is carried by the spring hinges in tension, and arcuate means adjacent the spring hinges for limiting the curvature thereof. I

3. In a damper construction; a frame having an opening, a damper blade for the opening, a cross member extending from side to side of the frame across said opening, and a pair of spring hinges, one adjacent each end of the cross memberyeach spring hinge having its upper end-attached sto the cross member and its lower end attached to the damper blade whereby the weight of the damper blade is carried -by the spring hinges in tension, and arcuate means carried by the free ends of the spring hinges for limiting the curvature of said spring hinges. I

4. In a barometric damper, in combination, a frame :formed with mounting means at its rear for mounting it tothe line of a furnace, said frame being also formed with an opening, a damper blade in said opening, cross member means extending across said opening from side .to side .of the frame and in front of the damper blade, and a pair of flat spring hinges attached to said cross member and to the front of said damper blade.

5.. In a barometric damper, in combination, a frame formed with mounting "means at its rear 'for mounting it to the flue of a furnace, said framebeing also formed with an opening, a damper blade in said opening, cross member rmeans' extending across said opening from side each end of the cross member, each spring hinge having its upper end attached to the cross member and its lower end attached to the damper blade whereby the weight of the damper blade is carried .by the Spring hinges in tension, and ar- "bua'te means adjacent the spring hinges for limiting the curvature thereof.

'7. A draft stabilizer adapted to be mounted in an air passage leading to the interior of a furnace flue, comprising, a frame, a-swingable shutter, a hinge-support stationarily fixed to the frame adjacent the outer facewof the shutter, and a pair .of

laterally spaced hinges formed of thin, fiat spring steel, each of said hinges being fixed at one end to the hinge-support, and fixed at its othenend to the outer face of the shutter, whereby the shut ter may be swung from a'vertical position to an angular position with relation'to the .frame,'each of said hinges being longitudinally curved when the shutter has been swung to an angular position, said frame having an air'ppening controlled by the shutter, and said hinge-support spanning said air Opening above the bottom edge thereof.

8. -A draft stabilizer adapted to bemounted in an air passageway leading; to the interior-of a furnace flue, comprising aframe, a swingable shutter, a hinge-support stationarily fixed to the frame adjacent the outer face of the shuttenand a pair of laterally spaced hinges formed'of thin, fiat spring steel, each of said hinges being fixed at one end to the-hinge-suppor-t, and fixed at its other end to the outer face of shutter, whereby the shutter may be swung from a vertical position to an angular position with relation to the frame, the top end of each hinge being fixed in the hinge-support and the bottom end of each hinge being fixed to the shutter at intermediate portions of the shutter. l

- MORRIS W. CREW.

REFERENCES CI TED The following references are of 'record .in the file of this patent: v

I UNITED STATES PATENTS v Date I Switzerland .Dec. 16.. 1938

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