US2426786A - Automatic gas safety shutoff - Google Patents

Description

Sept. 2, 1947. R. E. NEWELL AUTOMATIC ms SAFETY SHUT-OFF Filed Jan. 13, 1945 MENTOR Patented Sept. 2, 1947 UNITED STATES PATENT OFFICE AUTOMATIC GAS SAFETY SHUTOFF Robert E. Newell, Irwin, re.

Application January 13, 1945, Serial No. 572,701

6 Claims.

This invention relates to automatic gas shutol! devices, generally referred to in the art as "safety pilots.

The objects of the invention are:

First, to provide a thermal element and valve combination, frictionless in operation.

Second, to provide a sturdy thermal mechanism quickly responsive to a pilot flame, but not responsive to changes in surrounding ambient temperature.

Third, to provide such mechanism with means for the simultaneous operation of a, gas valve and an electric switch, whereby electric ignition means, motors, solenoids, etc. may be synchronized in their action with that of the gas valve.

Fourth, to provide convenient means. for reversing the action of the flame responsive element relative to said gas valve.

Fifth, to provide a more compact valve and thermal mechanism than heretofore available.

In devices of this character where action of the thermal element is transmitted to operate a gas valve, the operative force is limited. Therefore, any moving parts involving friction, such as toggles, gland pins, diaphragms, etc. reduce the efl'ectiveness of the device, and may even prevent its operation. In the present invention the full benefit of the thermal action is obtained by transmitting its movement direct to a valve and contact switch without the use of sliding or rotating parts which would generate friction, and render the device unreliable.

Referring to the drawings:

Fig. 1 is a diagram illustrating, in exaggerated form, the action of the thermal mechanism, which is a portion of the entire safety device.

Fig. 2 is a plan view, partly in section, of the thermal mechanism, its support, and contacts operated by said mechanism.

Fig. 3 is a cross section, taken on the line X-X, Fig. 2.

Fig. 4 is a detail view of an insulating contact support, shown in Figures 2 and 5.

Fig. 5 is an external plan view of the entire safety device.

Fig. 6 is an end view of the apparatus shown in Fig. 5, looking from the right.

Fig. 7 is a, cross section of the thermal tube and burner at the point X-X, Fig. 2 in a slightly modified arrangement.

Fig. 8 same as Fig. 7, except that the burner is rotated to position the flame on the opposite side of the tube.

Fig. 9 is a cross section of the thermal tube, operating arm and burner, similar to Figures '1 and 8, except that the burner in Fig. 9 has a different port and flame formation, the ports being as indicated in Fig. 10.

Fig. 10 is a perspective view of the burner used in Fig. 9.

Fig. 11 illustrates the outer end portion of the thermal element in a vertical position.

Referring to Fig. 1, the thermal element is represented by the numeral I. It is a short piece of chromium-nickel alloy tubing, closed at one end, and secured at the opposite end to a longer piece of tubing 2 which supports it. The tube 2 may be of any suitable material, as it has no thermal function.

Within the tubes is an operating arm 3, preferably of ordinary drawn steel, case hardened for rigidity, and secured at one end to the thermal tube i, its free end extending in the opposite direction beyond the end of the support tube 2.

An external operating arm 4, of any suitable material, is secured to the closed end of the thermal tube I, as shown.

Suitable port means is provided in tube I for the propagation of a flame, in a manner later described, to contact one side of said thermal tube. The material of which the tube is composed possesses a high coeflicient of expansion, and a low heat conductivity.

Due to this fact, together with the insulating effect of the intervening air space within the tube, that is between the tube and arm 3, the side of the tube i next to the flame is heated several hundred degrees hotter than the opposite side of the tube. This causes the tube to expand more on the side adjacent the flame, than on the opposite side, whereupon a. progressive, transverse bending of the tube l occurs from one end to the other, increasing toward the end of the tube, as indicated.

This action is in a direction away from the flame, in a plane substantially in line with the axis of the tube and that point on the surface of the tube at which the maximum increase of temperature is maintained, or approximately midway between the base of the flame and its tip, as indicated in Fig. 3 by the line A--B. I

This bending action does not exceed the elastic limit of the tube i, so when the flame 5 is extinguished the tube soon returns to its normal position, thus moving the arms 3 and 4 to positions 3b and Id, respectively, Fig. 1.

As the tube I bends under heat, the inner operating arm 3 is carried with it, as indicated in Fig. l, the "end extending beyond the tube Imoving in the opposite direction, from the normal posilong, and a combined length of seven inches over all, including tubes I and 2, the movement from E to F will amount to approximately one thirty second of an inch, using an unmixed natural gas flame. With a manufactured gas flame, which is hotter, the movement will be greater. With a good Bunsen flame the movement will be still more.

The amount of movement corresponds to the heat of the flame, and in any caseis ample for the purpose for which it is intended.

Since the bending action of the tube I is caused only by a difference in expansion of opposite sides of the tube, its action, and the movement of arm 3 is not affected by an additional equal expansion of all sides of the tube, and which may be caused by increased ambient temperature, or by granular growth of the tube due to prolonged high ambient temperatures of one thousand degrees F. or

greater.

Any linear expansion of either the tubes'I or 2, or of the arms 3 and 4, does not affect the transverse action of the arms in any way. This should be clearly understood, as it is an important feature of the invention.

The external arm 4 is welded or otherwise secured at the free end of tube I, and its movement is therefore parallel with, and similar to, that of arm 3.

Now referring to Figures 2 and 3, which show the construction of the parts referred to in Fig. 1, it will be seen the tubes I and 2 are welded or otherwise rigidly secured together at,6, while the opposite end of tube I is closed by welding an enlarged head 3a, of arm 3, to the end of the tube; the external arm 4 being as above stated, also welded or otherwise firmly secured adjacent the closed end of tube I. At the opposite end of the assembly a stamping I is welded near the open end of tube 2, the purpose of the stamping 1 being to secure the entire assembly to a valve body, as later described. Closely parallel to the tubes I and 2, is a burner tube 8, which is supported bythe stamping I through which it passes.

A series of burner ports 9 are provided in the burner tube 8 opposite the thermal tube I, and so positioned as to direct an elongated sheet of flame 5, already referred to, crosswise around approximately half of the outer circumference of the tube. As indicated in Figures 3 and 5, the tendency of this flame is to spread and cling to the surface of the tube.- Although, no air mixer is provided, it burns with a blue color, and does not carbonize the tube I.

tact support II, also adjustable, and clamped by screw I2. A detail of the contact support II is shown in Fig. 4. Adjustment is made by means of the slot I3. Riveted to the support II are contact I4 and lead wire I5.

At the free end of arm 4 are secured insulating plate I6, contact I1, and flexible lead wire I8.

Now, referring to Figures 5 and 6, I9 represents a valve body, to which the mechanism just described is attached by securing the support plate I to the side of the bodyby four screws I2. A hole 29 is provided in the same side of the body to receive the extending end of tube 2, and the inner arm 3, said hole communicating with an axial bore 2|. Connecting with the bore 2I a tapped hole 22 is provided to receive a screw 23, which may be removed to provide access to the adjusting screw II]. I

Close beside the hole 20 is a, smaller hole 24, in which the burner tube 8 is inserted, said hole connecting with a small hole 25, Fig. 6, which leads to pipe tapping 21, connecting with a source of gas supply. This gas supply is independent from the main gas supply, and is regulated by a manually operated valve in the thermostator gas cook, notshown, but usually provided in connections with controls of this character.

The main gas supply enters the valve body at tapped inlet 28, Fig. 5, passing into the bore 2I, and from thence around the valve 29, into the enlarged bore 30, and through the outlet 3| in cover 32, to a main burner, not shown. The cover 32 is secured to the valve body by four screws 33, and is slightly recessed to receive the large end of a conical spring .34, the small end of the spring fitting over a boss on the back of the valve 29. Thus the spring 34 normally holds the valve in closed position, and also holds it in a central position in the bore 39.

A valve stem 35, riveted at the center of the valve, extends into bore 2I and is providedwith a conical recess at the end,- which rests upon the conical point of the adjusting screw I0.

It will now be understood that since the arm 3 operates entirely within the gas, and contacts the valve directly, no operating parts, involving friction, are necessary, as would be the case if the movement of the arm 3 had to be transmitted through to the valve from an external point,

Also, since the valve is both guided and supported entirely by the spring 34 and the adjust- The exact position of the burner tube a, relative to tube I, the design of the ports, and whether or not an air mixer is provided, may be determined by experiment, and will depend on the method of application of the device, and the work it has to do. Some. alternate burner arrangements are shown in Figures '7, 8, 9, and 10, and will be discussed later.

The essential point in all such arrangements must be that the mid point of that part of the flame which contacts the surface of the tube I must lie in a'plane corresponding to that in which the arms 3 and 4 move.

At the free end of the arm 3, Fig. 2, is an adjusting screw ID, the purpose of which is to adjust and operate a gas valve, as later explained; while secured to supporting plate I is an insulating coning screw I0, both of which members move with the valve, no friction of any discernable degree is involved in the operation of the valve. The operation of the valve is therefore positive and smooth, and the valve cannot stick in open position under any circumstances, a feature which is of first importance, since the main purpose of the device is to provide a positive safety cut-off of the main gas supply in event the pilot flame 5 is accidently extinguished.

As the operation of the thermal mechanism has already been described, little further explanation will be needed regarding the operation of the device. The assembly shown in Fig. 2 is attached to the body I9, in a manner permitting the movebe made special.

II, the contacts are first separated by loosening and sliding backcontact support II, and turning adiusting screw it until the valve is just closed.

Then the contact support II is adjusted until the contact l4 touches'contact l1, after which the screw I2 is tightened, and the cap 21 insorted in the body. The device is then ready for operation.

The circuit through wires II and I8 is of low voltage, and is intended to be used in connection with an electric igniter, not shown, adapted to ignite the pilot flame I. The use of a safety pilot valve, such as I have just described, prevents gas from reaching the main burner until ignition of the pilot flame has actually taken place, while the thermally operated circuit breaking'means renders the igniter inoperative after it has ignited the pilot flame I. Such a circuit can of course be used for other purposes as well.

Figures 7 and 8 illustrate an arrangement of the burner I, relative to the tube .l, by which the pilot flame I may be shifted from one side of the tube to its opposite side by merely rotating the e pilot flame is ignited or extinguished.

The need for such an arrangement arises in the manufacture of small safety pilot valves used to control gas bleed lines from diaphragm valves, where, in some cases the diaphragm valve is closed by back pressure when the safety pilot valve is closed, while in other designs of diaphragm valves the main valve is closed by the relief of pressure on the diaphragm, which is brought about by the opening of the safety pilot valve controlling the bleed line from the dia- The usual method is to make a special valve, operating in an opposite direction, although the thermal elenient usually operates in the same direction. ,In those types of safety pilots operated by bi-metal elements, the element is sometimes bent in opposite directions so that the active or expanding side or the bi-metal is on the opposite side, so that either the valve or the element must In the arrangement shown in Fig. 7 which is a cross section approximately at the point x x,

Fig. 2 looking toward the free end or the arm 3, the burner I is placed directly below the thermal tube I, with its ports to the left, thus causing the flame 6 to heat the left side of the tube i, and

therefore causing the free end of the arm 3 to move from right to left or in the direction AB.

In Fig. 8 this action is reversed by simply tuming the burner I one quarter turn to the right, whereupon the movement of the free end of arm 3 willbe from left to right, or in the direction A-C.

If desired, the arm 4 and the electrical contacts may of course be eliminated, althoug where the device is used on appliances requiring, electric fans, such as warm air furnaces, or where solenoids are used, the contact switch will be found of great advantage.

In Fig. 9 a form of burner is used such ms, is shown in detail in Fig. 10. Its ports are formed by slots cut crosswise of the burner, and, as indicated in Fig. 9, project a flat flame, spreading equally over half of the circumference of tube l, adjacenttothe burner.

In this case, the movement of the free end of I claim:

zontal position. In this position, however the effectiveness of the heating flame is reduced, and it a large valve movement is required it is advisable to use a Bunsen burner flame, of the type illustrated in Fig. 9.

It will be readily understood by those skilled in the art that the general design of the above device is such that it may be manufactured at low cost, with little labor, and will require a, minimum of those critical materials needed for war purposes.

The body ll may be made of square rolled aluminum bar. The machining of the body may be done entirely on an automatic machine, except the small hole 2!. The tubing parts are of course flnished on an automatic screw machine. The assembly is very simple, and when completed the control is sturdy, not likely to get out of order, and easily installed in all manner of conditions.

1. A flame responsive safety control for gaseous fuels including a. housing, a gas passage through said housing, a valve in said gas passage including a valve seat and valve closure member adapted to cut oil the flow of gas through said housing, said housing being provided with an opening communicating with said gas passage, and positioned to receive the free end of an operating member for operating the closure member of said valve, 8. flame responsive tubular element open at one end and closed at the other, means rigidly connecting the open end of said tubular element to said housing in communicative relation with said opening in the housing, a burner secured adjacent said tubular element having port means adapted to provide a continuous or serial elongated flame approximately parallel to the axis of said tubular element and impinging upon one side of said tubular element to cause it to flex in a progressively increasing degree from its flxed portion toward its free end, an operating member rigidly secured to the free end of said tubular element and adapted to move laterally within said tubular element in response to said flexing action, in a plane corresponding to that of the movement of said valve closure member, said operating member extending through the open end of said tubular element to engage said valve closure member, whereby said valve closure member may be actuated to open position by said operating member, and a. valve closing spring adapted to close said valve closure member when the operating member is in retracted position.

2. A non-friction, flame responsive, safety control for gaseous'fuels, comprising a housing, a main gas passage through said housing, a valve having a valve closure member for closing off the flow of gas through said housing, and a thermal device for operating said valve closure member to open position in response to the action of a pilot flame, said thermal device including a tubular element projecting fromsaid housing and having an open end and a closedend, said open end being fixed rigidly to said housing and communicating with said gas passage adjacent said valve closing member, a burner rigidly secured adjacent said tubular element and having port means adapted to provide arr-elongated flame or series of flames contacting a substantial length of said tubular element near its closed end, thereby caus- 7 ing a lateral flexing oi. the heatedportion of said tubularelement, an operating bar, rigidly secured at the closed or free end of said tubular element and extending through the tubular element to a point within said housing, to contact said valve closing member, said operating member being adapted to move laterally in response to the flexing action of said tubular element, without frictional contact with'said tubular element or housing, means on the movable end of said operating bar adapted to provide a free, adjustable engagement with said valve closure member, and to hold said valve closure member against lateral displacement, and a compression spring on the opposite side of said valve closure member adapted to urge said valve closure member to closed posie tion, and to also hold said valve closure member against lateral displacement when said operating bar is in a retracted position and out or engagement with said valve closure member.

3. A flame responsive control for gaseous fuels including means for simultaneously controlling a main gas supply and an electrical current, said control including a housing provided with a main gas passage, a. valve seat and valve closure member in said gas passage to control said main gas supply, a tubular element supported by said housing and communicating with said gas passage, said tubular element extending outward from said housing and being closed at its outer end, a pilot burner in fixed relation to said tubular element and provided with port means adapted to direct a flame or series of flames impinging on one side thermal tube and extending therefrom substantially parallel to the axis of said tube, with its opposite end free to operate the control member, a ilot burner tube fixed'to said body adjadirectly heat approximately one-half of the outer circumference of said thermal tube on one side only, causing a maximum unequal expansion and lateral flexing of said thermal tube, to operate said arm and control'me'mber.

. 5. A flame responsive control for gaseous fuels including a housin a gas passage through said housing, a valve seat and valve closure member in said gas passage for closing off the flow of gas through said control, a tubular extension connected with said gas passage and protruding from said housing in a direction substantially normal to the axis of said valve closure member, the outer portion at least of said tubular member being made of a metal having a high coefllcient of expansion and a low heat conductivity, said outer portion being closed at its end, an operating member for opening said valve, said operating member being rigidly secured at said closed only of said tubular element, causing said tubular element to flex in a transverse direction away from said flame, thereby shifting the position of the outer or closed end of said tubular element out of alignment with its normal axis, an internal operating arm extending lengthwise within said tubular element, rigidly secured at the closed end of said tubularelement while being free to move laterally at its opposite end, and engage said valve closure member, in response to the flexing movement of said tubular element, an external operating arm actuated in a similar manner to said internal operating arm, said external arm being rigidly secured on the outside of said tubular element at or near its closed end, while being -free to move laterally at its opposite end in response to the flexing of said tubular element, contact means secured to the free end of said external arm, a second contact means attached to the housing adjacent said first contact means in afixed position to be engaged or disengaged with said first contact means as a result of lateral movement of said external operating arm, said first and second contact means being part of an electrical circuit to be controlled simultaneously in conjunction with said valve closure member, threaded adjustment means at the end of the free end of said internal operating arm for adjusting the free engagement with said valve closure member, to open said valve closure in the presence of a pilot flame on said pilot burner, and adjusting means for one of said contact means, whereby said contacts may be adjusted to disengage simultaneously with the opening of said valve closure member, thus cutting off the electrical current at the same time that the main gas supply is opened.

4. A flame-actuated safety control including a main supporting body, a thermal tube fixed at one end to said body and extending outwardly, therefrom, a control member, an operating arm having one end secured to the outer end of said end of said tubular member and extending back through said tubular extension into the gas passage of said housing to a point adjacent said valve closure member, screw means positioned between said operating member and valve closure member and mounted on one of said members, to provide a free adjustable engagement between said members, said screw means being concentric with the axis of said valve closure member and centered at its point ofengagement in a pivot bearing in the other member, to guide said valve closure member against lateral displacement, a spring on the opposite side of said valve closure member tending to urge said valve closure member to closed position, a pilot burner, adjacent the outer portion of said tubular extension, connected with a gas supply and having port means adapted to provide a continuous or serial elongated flame, a. substantial portion of which impinges upon .that side'of said tubular extension toward which the free end of said operating arm must "move to opensaid valve, thereby causing that side of said tubular element to expand and flex the outer end portion transversely in a manner to carry the free end or said operating member in the opposite direction to move said valve closure member to open position.

6. A flame responsive control device including a housing, a control member within the housing, a hollow tube having one end secured to said housing and extending outwardly therefrom, an operating arm secured to the outer end of said tube and extending through the tube to a point adja-, cent said control member in the housing, a pilot burner provided with port means adapted to direct a heating flame to impinge upon one side only of said tube in a manner to cause the outer end of said tube to flex transversely in a given plane, to actuate said operating arm in contact with said control member in one direction, said pilot burner bein rotatably' mounted in said housing so that it may be turned to direct said 9 hating name upon the opposite side 0! said tube, tocauaeittoflexinthe sameplmebutinanoppoeite direction, thereby reversing the action or said operating arm and control member when the position of the flame is shifted.

ROBERT E. NEWELL.

REFERENCES cum) Number 10 1 UNITED STATES PATENTS Name Date Fonsece "Feb. 26, 1929 TePas Jan. 9, 1934 Hall July 20, 1920 Beam et a1. Jan. 6, 1942 Daugherty May 16, 1944 Hialey et a1 Nov. 28, 1944 Higley July 28, 1942 Burch Oct. 31, 1944

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