US395382A - Automatic damper - Google Patents

Description

G. H. CROWBLL.

AUTOMATIC DAM-PER.

`Patented Jan. 1, 1889.

un em. lj C1 (o Model.)l

NiTEo STATES PATENT Erica.

GEORGE HEURY CROIYELL, OF BERLIN FALLS, NEV HAMPSHIRE.

AUTOMATIC DANI PER.

SPECFICATION' forming part of Letters Patent No. 395,382, dated January l, 1889.

Application led April 4, 1888.

To all whom it may concern:

Beit known that I, GEORGE HENRY (taow- ELL, a citizen ofthe United States7 residing` at Berlin Falls, in the county ot' Coos and State of New .Ilampshire, have invented certain new and useful Improvements in Automatic Damp ers; and I do declare the following to be a full, clear, and exact description of the invention, such as will' enable others skilled in the art towhich it appertains to make and use the same, reference being had. to the accompanying' drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

My invention relates to dampers, and more especially to that class known vas automatic dampers,7 which are opened and shut by devices that are sensitive to the changes of temperature to which they are subjected.

My invention is applicable to all kinds of dampers, but is particularly adapted for ovens. It is arranged in a suitable opening in the door or in the wall of the oven. As ordinarily constructed, these dampers operate in connection with a stationary slotted basepiece or gridiron, the extent of opening being always the same for any given degree of temperature. In my invention, however, I make the gridiron adjustable, and thereby am enabled to vary the extent to which the damper will open at any given temperature, ranging from wholly open to nearly or entirely closed.

In the drawings, Figure l is a front elevation of my device; and Fig. 2 is a rear elevation, upside down from the position shownin Fig. l. Fig. is a liorizontal section, and Fig. 4f is a vertical section.

A is a shallow box or easing, deep enough to contain the sliding damper and the thermostatc devices. The front of the casing has one or morel slots, u, for the admission of air to the oven,V the easing being fastened over an opening preferably in the oven-dom'. I have shown two slots, a, in the drawings, though it is evident that the number may be varied, as

desired. Inside the easing is an adjustable gridiron, B, consisting ot' a sheet of metal covering, the slots a, and provided with a series of rectangular openings, l), opposite the slots a. The solid portions between the openings Z9 are about one and one-half time as wide as the openin gs themselves.

sei-in N0. 269,568. (No man.;

Superposed upon the gridiron D is the damper C, consisting of a sheet of metal pro vided with a series of rectangular openings, c, of substantially the same size and shape and arrangement as the openings l) in the gridiron, and adapted to register with them. At each end of the gridiron and damper are two slots, 2) c', through which pass headed studs A', projecting from the casing A. The length of the slots c governs the range of movement of the damper C.

To enable the gridiron B to be moved at will, a knob, D, is provided on the outside of the casing, mounted on a short shaft, d, that passes through the gridiron B and carries on its inner end a disk, D. A slot, b2, in the gridiron permits the passage of the shaft (Z and allows the gridiron to move back and forth. The disk D carries a wrist-pin, d', which enters a curved slot, b3, formed in the gridiron B eccentric to the shaft d. Upon turning the shaft d by means of the knob D, the pin d causes the gridiron to move. An index, e, traveling over a graduated scale, E, enables the gridiron to be set at any desired point in the range of movement', which is equal to one-h alf the width of one of the openings b.

The damper C is arranged to be moved automatically by the following means: Fast i ened to the inside of the casing A is one end of a thermostatic bar, F, composed of two strips of dissimilar metal-such as brass and steek-having unequal rates of expansion under heat. The strips are riveted lirmly together, and to the free end of the bar thus vformed is secureda jaw, G, in which is pivoted one end of aV link, l-I, connecting the jaw with one arm of a bell-crank lever, I, fulcrumed on the stud A. The other arm of the lever is forked, and engages with a pin, K, projecting from the damper C. lVhen the bar j 'E is expanded by heat, its free end moves down, owing to the greater expansion of the upper strip of metal. This movement is comniunieat-ed to the lever I, and causes the damper to slide toward the right in Fig. 2. The openings l) c in the gridiron and damper are so related that when both are at their eX- treme left-hand position the openings will not register, but when at their extreme right-hand i position the openings will register. Further- IOO more, when the damper C is in its extreme l lett-hand posit-ion the gridiron B can be shifted to either limit o'l' its movement without opening a passage through the damper. New, when the gridiron and damper are both at the left hand it requires ybut a moderate degree ol:` heat to expand the bar F enough to fully open. the damper, thereby admitting cool air to .relieve the temperature of the oven. It, however, the gridiron .l is set at the righthand limit, it will require a considerable expansion of the bar to open the damper, since the damper must slide a greater distance toward the right in order to cause the openings t) c to register; but since the gridiron B can be set at various intermediate positions it Afollows that the damper C can be required to move to a greater or less distance from its extreme left-hand position before the slots I) c will register. l'n this wav the degree of heat required in the oven. can be closely regulated between certain extremes and the oven kept at a predetermined temperati'ire.

rlhe index e and scale E enable the gri diron B to be set at anvpoint and indicate the tem* perature which exists inside the oven. It the oven becomes too hot, the damper gradually opens to admit cool air and `gradually closes as the temperature lowers 'toward the predetermined point. It is obviousv that my improvement ean'be applied to automatic dampers of various kinds, and may be varied in dee tail. without departing Vfrom the spirit of the invention.

l am aware that it is not 'new to use an adj ustable gridiron with an automatic damper, and that a piu engaging with a slot is an old adjusting device. I do not claim an)v of these parts separately, but merely in eomli ination, for the purpose set forth.

llaving thus described my invention, what l claim7 and desire to secure by Letters Patent, isM v The combination, with the casing A, having the studs A and slots a, oli' the reciprocating gridiron l, having openings b, straight slots b and if?, and eccentric slot Us, the shaft d, passing' through the slot U2, and carrying disk D provided with pin d', engaging with slot U", the reciprocating damper C, haring the openings c and superposed upon the gridirou '13, the th ermostatic bar li, an d tl 1e bell-crank lever l, engaging with the damper C and coun ected with the bar F, all combined and operating substantially as and Vfor thepurpose set forth.

ln testimony whereolI l aliix in v signature in presence of two witnesses.

GEORCrE HENRY CRO\\'ELL.

l'Vitnesscs:

R. i CHAMBERLIN, VALENTINE GRAY.

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