US2482232A - Thermostatic device - Google Patents

Description

Sept. 20, 1949. J. o. YElDA THERMOSTATIC DEVICE Filed Nov. 3, 1944 l 4w] w u 4 0 4 T A J w M nmH fl ll! 2 s A M 2 m a Kw a m.

Patented Sept. 20, 1949 UNITED- STATES PATENT OFFICE THERMQSTATIG DEVIGE John Yei lal, Herculaneum, Mo., assignor, by mesne assignments, to Missouri Automatic Control Corporation, a corporation of Missouri Appli ation November 3, 1944, erial No- 561,775.

2 Claims. 1

This invention relates to a thermostatic device, and more particularly to one that is responsive only to variable temperature conditions within itself.

An object of the invention is to provide a simple thermostat of this kind, which is structurally strong and which functions r pidly.

A iurther object is to provide a thermostatic device in the form of a channel-shaped member designed so that flame applied to the flanges will cause av portion of them to expand more than the corresponding portion of the bottom wall of the channel, with resultant distortion of one end of the member. More particularly, it is an object to provide such a channel member in combination with a heat absorbing member adjacent the bottom wall to aid in the heat differential between the flanges and the bottom wall.

An especial object is to provide such a channel-shaped member in a U-shape, to attain compactness and maximum movement of the actuating end thereof.

In the drawings:

Fig. 1 is a side elevation of the device;

Fig. 2 is an edge elevation of Fig. 1; and

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 1.

The device includes a base member In adapted to be secured to a proper support by screws passing through holes II. The base I!) may be attached to the wall of a furnace adjacent a pilot burner shown at 12.

The base has a projection l3 preferably rounded, as shown at 14, at its upper end.

A channeled strip of uniform composition, generally indicated at l6, has a back leg ll attached at one edge of the projection l3 on the base Ill. The channel strip [6 is U-shaped having a bight portion l8 curved over the curved portion at the top of the projection l3. Preferably the projection 13 is no Wider than the channel section. The channel also has an operating leg I 9 extending down the other edge of the projection l3 closely adjacent thereto but spaced therefrom. At its free end, the arm I 9 carries a double throw switch blade 20 having a switch arm 2| supporting two contacts 22 cooperable with either contacts 23 on the base ID, or with contacts 24 supported on a bracket 25 mounted on and insulated from the base In. This switch is typical of devices to be operated by the element. Each of the contacts 22 and each of the contacts 23 is insulated one from the other. The various contacts are adapted to be connected by leads 26 with suitable circuits,

2 such as solenoid valve circuits, or. the like, con, trolling the flow of fuel to the burner.

The. channel section should be rather narrow, with flanges that are deep relative to its width. For example, a channel with a A" space between flanges deep has proved successful. The depth of the flanges should be such that a flame impingin upon their outer portions will not impinge with equal heat upon the bottom wall.

Operation This control is adapted to be used. in such places as a furnace, where it is subject to variat-v tion in ambient temperatures. Despite normal changes in ambient temperature, that afiect all parts of the element, it will also respond to the presence or absence of a flame F at the pilot burner l2.

When the element is not subjected to the pilot flame, it will assume the position shown in Fig. 1, wherein the contacts '22 close with the contacts 24. This may control a circuit to an igniter for the pilot burner. When the flame F impinges against the channel element. a large quantity of heat is introduced into the flanges. The narrow and deep channel section will take most of the heat in the flanges, which thereby expand to a greater degree than the bottom wall expands. As a result, the channel element warps, causing the contact member 20 to separate the contacts 22 from the contacts 24, and to move to bridge the contacts 23. When the device is used as a pilot flame detector, this operation will then permit a fuel valve circuit to close.

The warping is accentuated by having the bottom wall of the channel located so as to give off heat constantly. While the flanges are bathed in the flame, the bottom wall is more or less spaced from the flame. Also the back side is to a large extent, and preferably adjacent the flame, disposed against the relatively cooler projection 13, which can absorb heat therefrom, and, in any case, is exposed to air at lower temperature than the temperature of the flame. Hence the outer part of the flanges will always be hotter than the inner parts, during impingement of flame.

Curving the element to the U-shape increases the warping, as it increases the proportion of the element that is in direct contact with the projection l3. The spacing of the free arm l9 from the projection I3 is preferably the minimum, being only enough to permit proper switch operation.

Ambient heat afiects all parts of the device cause the switch to function. It will be seen that the device is of a rigid construction, free of pivots and like parts subject to wear and displacement. 7

What is claimed is: a 1. In a thermostatic device, tion extending from the base and providing p- .10 the proper action of the expanding parts to;

channel-shaped member of uniform composition secured to one side of the projection near the base and extending along said side in contact therewith, said member extending around said connecting'side of the projection in contact with a portion thereof and extending down the other side of the projection in spaced relation thereto, said channel-shaped member having the flanges thereof extending outwardly from the Projection, actuated means associated with the free end of 5 said member, the free end of said member being adapted to assume and remain in one position a base, a projecposite sides and a connecting side, a unitary;

heat-responsive channel-shaped member secured to one side of the projecting portion remote from the connecting side, extending along to the flanges of said member.

said sidein contact therewith, extending around 1 said connecting side of the projecting portion and extendingdown the other side of the projecting portion, said member being substantially uniform in composition, actuated means associated with the free end of said member, said member being adapted to be impinged upon by a flame applied to the flanges thereof.

2. A thermostatic device comprising a base, a projection extending from the base and including opposite sides and a connecting side remote from the base, a unitary heat-responsive upon impingement of the flame on the flanges thereof and being adapted to assume and remain in another position in the absence of heat greater than ambient temperature, the projection being adapted to absorb heat from the bottom wall of said member to accentuate the difference in temperature between the flanges and the bottom wall of said member when a flame is applied 7 JOHN O. YEIDA.

REFERENCES" CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS '7 Number Name 7 Date 2 1,233,223 Hachmann" July 10, 1917 2,064,909. Hahn Dec., 22, 193 2,080,385 Congdon f 'May 11, 1937 2,288,746 7 Samuels July 7,

Images