US2017725A - Thermostatic structure - Google Patents

Description

Oct. 15, 1935. R. E. NEWELL THERMOSTATIC STRUCTURE Filed Jan. 28, 1935 Patented Uct. iii, 1935 UNITED STATES PATENT OFFICE THERMOSTATIC STRUCTURE Application January 28, 1935, Serial No. 3,885

5 Claims.

This invention relates to thermostatic structures for the operation of control devices such as valves, switches, or the like, in various types oi. systems. a.

In my United States Patent No. 2,000,294 dated May 7, 1935, is described a thermostatic structure for operating valves, switches, or the like, and comprising essentially a support, an element having a return bend intermediate the ends thereof and having oppositely disposed arm portions extending from said bend, one of said arms being rigidly secured to said support, and, adjacent said return bend, a cross bridge extending between and rigidly secured to the arms of said element and arranged to move one of said arms relative to the other as a result of any difference in the temperature of the return bend and that of the cross bridge.

In the preferred structure of the above mentioned patent, the arms 01 the U-shaped element are adapted to extend through holes in the crossbridge, the arms being swaged to hold the crossbridge in place adjacent the return bend 0! said U-shaped member. In the manufacture of such a device, it was found desirable to change said holes to slots to take care of any slight variations in form that might occur in shaping the U-shaped member. After positioning the cross-bridge on said U-shaped member, the edges of said slots were pressed around the arms of said member to rigidly secure the cross-bridge to both arms.-

It is necessary to anneal the assembled structure in order to remove any stresses set up in the metal by the bending or shaping of the members. Otherwise, the completed unit will not remain stable in its position relative to the control member to be operated. In the annealing process the cross-bridge and the arms of the U-shaped member change slightly their position with respect to each other and thus tend to loosen the cross bridge which is secured to said arms. This creates difliculties in the manufacture of a standard product.

When thermostatic expansion and movement takes place in such a structure, the cross-bridge, being rigidly secured to both arms, must necessarily flex slightly because of the spreading of said arms. This flexing, of course, consumes a portion of the power developed by the structure.

By my present invention, I provide an improved thermostatic structure which overcomes the aforementioned d'ifliculties, and presents new and original features through which greater power, efficiency, and quicker action, as well as uniformity and lower cost, may be obtained when the article is manufactured in quantities.

In the accompanying drawing, I have shown my invention as embodied in a structure particularly adapted to be used in connection with s a pilot flame safety valve or switch. However, it is not necessarily limited to such structures. As will be explained later, the device may also be used as a regulation thermostat to control the temperatures to which it is subjected. 10

In the drawing-- Figure 1 is an elevation view of a preferred form of the present unit conveniently mounted and arranged to actuate a control member in accordance with temperatures created by a pilot l6 flame;

Figure 2 is an elevational view of the structure dissociated from supporting means and the pilot li Figures 3 and 4 are side elevations of structure 20 shown in Figure 2;

Figures 5 and 6 are detail views of the new adjustable cross-piece; and

Figure 7 shows my invention as embodied in a structure similar to that of Figure 1 but having 5 a modified form or cross-piece and another form of burner particularly designed to act as a pilot in connection with this device.

As shown in Figures 1 to 6, inclusive, the member I has a flexible return bend 2 with arms! 3' and 4 extending therefrom. The arm 3 is longer than arm 4 and has its end portion 5 shaped' and adapted to be conveniently attached to support 6 by screw threads and held in place by lock nut I. This adaptation of the end portion 5 oi. as the longer arm 3 merely eliminates the necessity of a bracket or similar support.

The shorter arm 4 is allowed to remain free of the support and may be of any desired length to obtain sufiicient amplification of movement. 0 An adjustable actuating pin 8 is inserted in the end of arm 4, and cooperates with a rod 9 or any other suitable means provided to operate the control to which the device may be attached. The slit I0 is designed so that a blow of a hammer, or the like, on the end 01 arm 4will tighten the threads about the adjustable actuating pin 0, thus looking it against accidental displacement.

Mounted on the end portion 5 oi. arm 3, and extending through hole ll therein, is a burner I2, positioned to direct the flame l3 upon a thermally responsive cross-piece it, one end of which abuts against the arm 4, while the other end extends through and is adjustably secured to the opposite arm 3 by screw threads l5 and lock nut l0. Proper adjustment of the cross-piece II is facilitated by screw-driver slot II.

In assembling, the bent member is first annealed to relieve the strains incidental to shaping. The cross-piece is inserted and adjusted so that the end opposite the threaded portion abuts against the shorter arm of the member and the cross-piece is then locked in place. The end portion of the longer arm of the bent member is attached to the support and the actuating pin placed in the end of the free arm and operatively connected with the control member, and adjusted until the desired temperature range is obtained. The structure is then ready for use.

The flame i3, impinging on the cross-piece i4, causes it to expand and move the free arm 4 to a position such as shown by dotted lines in Figure 2. Such movement is amplified by the length of said arm 4, the end of which actuates the bar I which in turn operates a suitable control. When the flame is removed, the cross-piece cools and contracts. Since all strains have previously been removed from the member I by annealing and since the movement of said free arm is extremely small when compared to the size of said member I, the natural resiliency of the metal of which said member is formed causes it to return to its original position.

The member i may be formed of a flat strip of suitable material, the strip being wide enough so that the member is more or less rigid except for the portion forming the flexible return bend, which portion is narrowed or otherwise reduced in size to permit flexing. The member must also be large enough and formed of material having sumcient strength to operate properly the control means for which it is designed, without taking a set.

The cross-piece may be located at any desired point on the member I. However, I have found the most desirable position is one in which the cross-piece is adjacent the flexible return bend of said member, as shown in Figure 1, as this gives the free arm maximum movement amplification. This cross-piece should be only large enough to have suflicient strength to carry the load imposed upon it at the highest temperature to which the device is subjected. Such a cross-piece is then small enough to reach maximum temperature quickly and to cool rapidly when the flame is removed therefrom.

It is easily seen that by merely providing a cross-piece of a material having a considerably higher coefllcient of expansion than that of the member I, this structure can be used successfully as an ordinary thermostat for accurate temperature control or regulation. One of the advantages of an adjustable cross-piece of the type described is that it may be quickly and easily removed and another cross-piece, which may have a different coefllcient of expansion, readily inserted. This rapid conversion from one type of thermostat to another naturally increases the value of the structure, especially from a manufacturing standpoint.

In Figure 7, I have shown a structure, somewhat similar to that of Figure 1, in which a member ll has a flexible return bend I! with arms and II extending therefrom, arm 20 being attached to a support I! and arm 2| being free of said support and operatively engaged by means of pin 23 with any suitable control operating means such as rod 24. The thermally responsive cross-piece II has one end securely fastened to arm III and extends therefrom to the other arm and abuts against the end of screw 26. This screw 26 is adjustably supported by arm 2| and is locked in place by nut 21 and serves as an adjustable bearing contact point for the arm 2|.

The runner burn-er 28 is supported substantially parallel to the cross-piece by any convenient method (not shown). The burner tube extends through hole 29 in arm 2i but not touching said arm and thence through hole 30 in arm 20, the burner jets of the runner being arranged so that a series oi small flames 3| impinges on the crosspiece 25 and at least one flame 32 burns outside of the structure and thus presents a convenient method of lighting a main burner 33.

This type of pilot burner is particularly advantageous for installations in which it is impossible to locate the structure close enough to the main burner so that a pilot burner as shown in Figure 1 would ignite said main burner. It is to be noted that either type of burner may be used with either design of cross-piece, thus both the member I of Figures 1 through 4 and the member l8 of Figure 7 contain openings suitable for the use of either type of burner.

The structure shown in Figure 7 operates in a manner similar to that of the device of Figure l. The flames 3| impinging upon the cross-piece 25 cause it to expand and move arm 2| which actuates control member 24. is extinguished it is reignited by the other flames of the runner. If, for any reason, the entire pilot runner is extinguished, the cross-piece will cool, contract, and allow arm ii to return to its original position.

The advantages of making the cross-piece as described in this specification are quite clear and distinct, especially from the manufacturer's viewpoint. Any small errors in the forming of the bent member or slight changes of shape in the annealing of said member are easily taken care of by the adjustable feature. Loss of power caused by the necessity of flexing a bridge rigidly secured to both arms of said member is eliminated, thereby the efliciency of the structure is increased.

In case one jet flame One arm of said member having a free pivotal 5 contact with the end of said cross-piece, rather than being rigidly secured thereto, permits a more uniform action. With this increased freedom of movement, and the additional power available. the device operates in approximately one-half of the time required by the one shown in my aforementioned copending application. The crosspiece of the preferred design allows rapid and easy removal and replacement of said cross-piece if desired, and the simplicity of forming and assembling the parts materially reduces manufacturing costs.

Though I have shown and described a preferred embodiment and a modification of my invention, I do not intend to be limited thereby, as my invention may be otherwise embodied within the scope of the appended claims.

I claim:

1. A thermostatic structure having, in combination, a support, a member having a flexible return bend with arms extending therefrom, one of said arms being fastened to said support, a thermally-responsive cross-piece secured to one of said arms and in free bearing connection with the other arm, whereby thermostatic expansion or contraction of said cross-piece will result in a sensitive flexing of said bend and movement of the free arm of said member, and means for adjusting said free bearing connection.

2. A thermostatic structure having, in combination, a support, a member having a flexible return bend with arms extending therefrom, one of said arms being fastened to said support, a thermally-responsive cross-piece secured to one of said arms and operatively engaged, by free bearing contact, with the other arm so that thermostatic expansion or contraction of said cross-piece will result in a sensitive flexing of said bend and movement of the free arm of said member, and screw means for adjusting said free bearing contact.

3. In a thermal control system, the combination of a member having a flexible return bend with arms extending therefrom, means connected with one of said arms for supporting said member, a thermally-responsive cross-piece extending from one of said arms to the other and havin adjusting means cooperating therewith for obtaining operative engagement of said cross-piece with said arms, whereby a sensitive flexing of said bend and movement of the arm that is free of said supporting means will result from thermostatic expansion or contraction of said cross-piece, and a control member operatively connected with said movable arm.

4. In a thermal control system, the combination of a support, a member having a flexible return bend with arms extending therefrom, one of said arms being fastened to said support and the other arm operatively engaged with a control member, and a thermally-responsive cross-piece secured to one of said arms and in free bearing connection with the other arm, whereby thermostatic expansion or contraction of said crosspiece will result in a flexing of said bend and movement of the arm which is operatively engaged with aforesaid control member.

5. In a thermal control system, the combination of a support, a member having a flexible return bend with arms extending therefrom, one of said arms being fastened to said support, a thermally-responsive cross-piece secured to one of said arms and operatively engaged, by free bearing contact, with the other arm so that thermostatic expansion or contraction of said cross-piece will result in a sensitive flexing of said bend and movement of the arm that is free of said support, a control member connected to said movable arm, and means for adjusting said free bearing contact.

ROBERT E. NEWELL.

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