US2815034A - Safety pilot - Google Patents

Description

7 M. F. KAUTZ 2,815,034

SAFETY PILOT Filed Oct. 18, 1954 IN VE N 70/? I5. MURRELL F. KAUTZ ATTORNEY couple.

*SAFETY PILOT Murrell .F. ,Kautz, Minneapolis, Minn., assignorto Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application October 13, 1954, Serial No. 462,991

6 Claims. (Cl. 13765) This invention relates to safety devices for controlling flow of fuel to burners. More particularly, the invention is concerned with a safety valve which is capable of shutting off the flow of gas to a pilot burner or a main humor or both in the event that the :pilot burner for igniting a main .burner becomes extinguished, which would make it unsafe for gas to continue to flow to the space where the gas is burned.

Devices of this type, broadly, are well known in the heating controls art and, while most of the devices currently being used are of the thermocouple actuated or controlled type, there are particular installations which render it advantageous to use a non-electrical flame sensing control means for the safety device rather than a thermo- Also, in the event that the material needed for thermocouples becomes scarce for any reason, a nonelectrical type of safety device would have to be used.

One of the objects of this invention is to provide a. safety device which is controlled by a non-electric flame sensing unit.

Another object of the invention is to provide a mercury filled bulb and bellows unit having a mechanism actuated 'by the expansion or vaporization of the mercury in the bulb to hold the safety device in its on position.

A further object is to provide a mercury filled bulb and bellows controlled valve sub-assembly which is sufliciently small so as to be able to replace or to be substituted for a thermocouple and electromagnetic control mechanism sub-assembly such as that disclosed in the copending application of James M. Cunnien and Melvin G. Sogge, Ser. No. 356,202, filed May 20, 1953, on a Safety Valve.

A still further object of the invention is to provide a mechanically actuated safety mechanism for a control which provides a strain release to prevent damage to the mechanism in the event of exceptional movement of the condition sensing means due to unusual condition changes.

Another object is to provide a safety control that has to be manually reset to its on position and which is of very simple and compact construction.

A further object of the invention is to provide an actuating mechanism between a control and a condition responsive means wherein a single biasing means coacts with a pivot for moving a lever into operative and inoperative positions and also provides a strain release for the condition responsive means.

Still further objects of the invention will become .apparent upon reading the following detailed description of the invention, in conjunction with the accompanying drawings, wherein:

Figure 1 of the drawing illustrates the invention in vertical cross-section and Figure 2 is a cross-sectional view of the invention taken along line 22 of Figure 1.

While it is obvious that the safety mechanism of this invention may also be adapted to control the operation of one or more electrical switches, the invention is being illustrated in its application to a safety valve which is States Patent .2 adapted to provide shutoff of all gas flow to the main burner and a pilot burner for the main burner in a conventional domestic heating system.

As can best be seen in Figure 1 of the drawing, the safety device consists of a lower casting 10 having an inlet 11 and an outlet 12 with a dividing wall 13 therebetween, and a pair of outlets 14 for selectively connecting a conduit (not shown) leading therefrom to a pilot burner. The wall 13 has a valve seat 15 formed therein to receive a valve head 16 that controls the fiow of gas to the main burner. The outlets 14 connect with .a bore 14a that terminates in a valve seat 17, which is "adapted to .receive a valve head 18 that controls the flow of gas to the pilot burner.

An upper casting 19 is secured to "the lower casting 12, with a rubber or other suitable gasket 20 therebetween, by means of bolts 21 in a conventional manner. Supported by the upper casting on a pivot 22 are two levers 23 and 24 which depend into the lower casting, with the lever 23 extending through an opening 24a in the lever 24 and the lower ends of the levers being biased toward each other by means of a coiled tension spring 25. The movement of the levers toward each other is limited by engagement of the lever 23 with the lever 24 at the lower end of the slot 24a. The intermediate portion of the lever 23 has an opening 23a therein for the reception of a valve stem 26 connected to the pilot valve 18. An arm extension 23]), extending to one side of the pivot 22, and an arm extension 24b on the lever 24, extending to the left of the pivot 22, are adapted to be engaged by a floating lever 27 by inward movement of a manually operable reset button 28 connected to the floating lever by means of a plunger 29. The button is outwardly biased by means of a coiled compression spring 30 which holds packing 31 tightly around the plunger 29 by reacting against a button 28. The lever 27 is held against displacement with respect to the levers 24 and 23 by means of downwardly depending ears 27a which extend alongside of the pivot 22. The functioning of the reset button and its cooperation with the levers 23 and 24 will be described hereinafter.

The safety mechanism for actuating the above mentioned main and pilot valves includes a bracket 32 that is supported in the upper casting 19 by means of a bellows unit 33 having a shank portion or spud 34 which is externally threaded and extends through an unthreaded opening 35 in the housing 19, substantially in axial alignment with the pilot valve bore14a, and through an opening 36 in the bracket 32. The bracket is clamped against the inner wall of the casting 19 by means of a nut 37 screwed upon the shank 34 tightly against the bracket. The bracket has a guide opening 38 in the right hand end thereof and a J-shaped support 39 extending between the side walls of the bracket 32. A guide bore 40 in the support 39 is in axial alignment with the guide 38 and both support and guide the valve stem 26 in rectilinear sliding movement toward and away from the valve seat 17. The stem 26 is biased toward the valve seat 17 by means of a coiled compression spring 41 bearing at one of its ends against the right hand end of the bracket 32 and at the other end against a cup shaped abutment mem ber 42 held in position on the stem 26 by means of two clip rings 43 resting in annular grooves in the stem 26. The stem 26 is operably connected to the lever 23 by having the abutment 42 engage one side of the lever 23 and another abutment member 26a, fixed to the stem 26, engaging the other side of the lever 23. There is enough clearance between the ends of the opening 23a in the lever, and lost motion between the lever 23 and the stem abutments as to enable the pivotal movement of the lever 23 to actuate the stem and the pilot valve carried thereby between open and closed positions of the valve.

The valve 13 and the valve 16 are adapted to be held in their open positions by means of a bell crank lever 44 carrying a pivot 45 that is horizontally slidable in slots 46 formed in the side walls of the bracket 32. The bracket 39 has two threaded openings 47 which receive an adjusting bolt 43, which has a head portion 49 that extends across the slot 46 to form an abutment for the pivot 45, there being an opening 50 in the lever 44 to permit the head 49 to engage the pivot 45.

Lever 44 has a large opening 44a therein that permits the stem 26 and the upwardly extending arm 39a of the bracket 39 to extend therethrough. The lever 44 also has an offset extension 44b of narrow Width that is vertically slidable in a guide slot 32a in the right hand end of the bracket 32. Near the end of the other arm of the lever 44 are laterally spaced forked ears 51 which receive one end of a torque spring 52 having a loop intermediate its ends and having its other end anchored in holes 53 in the bracket 32. This spring constantly biases the bell crank lever 44 counterclockwise on its pivot 45 to urge the right hand end of lever 44 away from the valve stem 26. The lever 44 is actuated in a clockwise direction by means of a plunger 54 welded or otherwise connected to a diaphragm 55 welded at its side to a rigid cup shaped housing 56, which, in turn, is connected through a capillary tube 57 to a bulb 58. The housing 56 is preferably Welded to the spud 34.

The bulb, capillary tube and the space between the diaphragm 55 and housing 56 are completely filled with mercury or any other suitable volatile liquid which when heated by the flame from a pilot burner P will cause the diaphragm to move to the right and actuate the lever 44- in a clockwise direction. The movement of the lever 44 in a clockwise direction will, if the stem 26 has been moved inwardly to position the pilot valve in its open position, cause that portion of the lever 44 at the right hand end of the opening 44a to engage in a notch 26b in the valve stem.

As long as the bulb 555 is being heated to vaporize the mercury therein, stem 26 will be held in valve-open position against the bias of spring 41, after the manually reset mechanism has been released. Upon the pilot flame becoming extinguished, mercury vapor in the bulb 58 will condense permitting the mercury in the bellows 33 to contract and a spring 59 to force the diaphragm 55 toward the left, thus permitting the torque spring 52 to pivot the lever 44 counterclockwise to follow the plunger 54. This movement releases the valve stem 26 to permit the valves to be closed by the spring 41.

Operation With the above described safety device installed in a heating system, with the inlet 11 connected to a suitable source of gas supply, the outlet 12 connected to a main burner and one of the plugs removed from one of the outlets 14 and the outlet connected to a pilot burner located to heat the bulb 58 and to ignite the main burner, the safety device, which is illustrated in its shutdown position, may be placed in operation in the following manner.

By pressing inwardly on the button 28, the left hand end of the lever 27, as viewed in Figure 1 of the drawing, will engage the arm 24b and the right hand end of the lever 27 will engage the right hand end of the arm 2311. Further inward movement of the button 28 will cause the left hand end of the lever 27 to react against the arm 24b to hold the main valve 16 seated While pivoting the lever 23 about the pivot 22 an amount sufiicientto move the notch 26b in the stem 26 to the left of the right hand end of the opening 44a in the lever 44 and to open the pilot valve 18. This movement of the lever 23 stretches the spring 25 by moving the lower end of the lever 23 away from the lower end of the lever 24.

With the elements of the safety device held in this position, the pilot burner may then be ignited and, after a sufficient time has elapsed to cause the mercury in the bulb 58 to become vaporized, expanding the bellows chamber and pivoting lever 44 clockwise to cause it to engage in the notch 26b, releasing the button 28 will cause the spring 30 to move the button 28 and the lever 27 away from the arms 24% and 23b of the levers 24 and 23, respectively. As the lever 27 moves away from the arm 24b, spring 25 will cause the lever 24 to move toward the lever 23 at the lower ends thereof and thus open the main valve 16. It is seen that no gas can flow through the main valve unless there is a flame present at the pilot burner for igniting the gas at the main burner.

If for any reason there should be any overheating of the bulb 58 as to cause mercury in part of the capillary tube to be vaporized and to thereby cause more movement of the diaphragm than is necessary to move the lever 44 into engagement with the notch 26b, no damage to the lever 44 or stem 26 will result from the lever meeting a rigid stop, due to the fact that the pivot 45 can slide in the slots 46, against the bias of spring 52, and thus provide a strain release for the movement of the plunger 54. Such movement would cause a slight movement of the pilot and main valves toward their closed positions, if the lever 44 is in engagement with notch 26b, but not enough to materially aifect the flow of gas to either the pilot or main burners.

The same strain release would be provided if for any reason the bulb 5% were heated sufficiently by means other than the pilot burner to cause clockwise movement of the lever 44 when the notch 26b is out of register with the end of opening 44a. It is thus seen that by a very simple arrangement of an adjustable pivot, lever and spring arrangement the control mechanism of the safety device may be readily calibrated through the same means which provides a strain release to prevent daamge to the operating mechanism upon the occurrence of unusual control conditions.

Upon failure of the flame at the pilot burner, the diaphragm chamber will contract as described above and cause the unlatching of the valve stem by the lever 44. Due to the fact that there is limited relative movement between the valve 18 and an abutment on the end of the valve stem 26, provided by a clip ring 260 on the end of the stem 26 within a socket in the valve 18, the pilot valve will first close under the bias of spring 4-1, followed by the closing of the main valve 16 upon further movement of the stem 26 against the bias of spring 18a, which holds valve 18 closed. It will be noted that the spring 4]. acts directly on the lever 23 which, in turn, bears against the lever 24 to hold the main valve to closed under the bias of spring 41. Upon the closing of the pilot and main valves, all gas to the burner is shut oif until the valves are again manually reset in the manner described above.

While the preferred embodiment of the invention has been described above, it will be obvious to those skilled in the art that modifications may be made therein without departing from the spirit of the invention. Therefore, the scope of the invention is to be determined solely by the appended claims.

I claim:

1. A safety control comprising a bracket, a control member movable between on and otf positions and being supported in said bracket, abutment means on said control member, means biasing said control member towards its off position, a lever supported on a pivot, said pivot being movably supported in said bracket, abutment means for said pivot, one portion of said lever having abutment means positioned to engage the abutment means on said control member when the control member is in its on position, condition responsive means for actuating another portion of said lever, means biasing said lever in a direction to move said other portion of said lever against said condition responsive means and said pivot against said abutment means, and means for manually moving said control means to its on position.

2. A control comprising a support, a control member movable betweeen on and ofi positions and having a supporting member movable in said support, abutment means on said supporting member, means biasing said control member towards its off position, a lever supported intermediate its ends on a pivot, said pivot being movably supported in said support, adjustable abutment means for said pivot, one end of said lever having abutment means positioned to engage the abutment means on said supporting member when the control member is in its on position, condition responsive means for actuating the other end of said lever, means biasing said lever in a direction to move said other end against said condition responsive means and said pivot against said adjustable abutment means, and means for moving said control means to its on position.

3. In a safety control, the combination comprising a bracket, a control member movable between on and off positions and having abutment means, means biasing said control member towards its off position, a lever supported intermediate its ends on a pivot, said pivot being slidably supported in a slot in said bracket, abutment means for said pivot, one end of said lever having abutment means positioned to engage the abutment means on said control member when the control member is in its on position, condition responsive means for actuating the other end of said lever, means biasing said lever in a direction to move said other end against said condition responsive means and said pivot against said abutment means, and means for moving said control means to its on position.

4. In a safety device, the combination comprising a support, a control member mounted on said support and movable between first and second positions and constantly biased toward its first position, manually operable means for moving the member to its second position, a pivoted lever having means at one of its ends for engaging and holding said member in its second position, a pivot for said lever supported for movement in a direction to permit the member to move toward its first position, means resiliently biasing said pivot against said abutment and said one end of said lever away from said control memher, a stop for limiting the movement of said pivot in the opposite direction, and condition responsive means for actuating said lever so as to pivot said means on said lever into engagement with said control member for holding it in its second position when a predetermined condition exists and freeing said member for movement to its first position when said condition ceases.

5. The combination comprising a support, a control member movably mounted on said support between first and second positions and constantly biased toward its first position, means for moving the member to its second position, a pivoted lever engaging and holding said member in its second position, a pivot for said lever supported for movement in a direction to permit the member to move toward its first position, an adjustable stop for limiting the movement of said pivot in the opposite direction, condition responsive means for actuating said lever so as to pivot said lever into engagement with said control member for holding it in its second position when a predetermined condition exists and freeing said member for movement to its first position when said condition ceases, and means for biasing said lever towards said condition responsive means and said pivot towards said abutment.

6. In a safety device, the combination comprising a support, a control member movably mounted on said support between first and second positions and constantly biased toward its first position, means for moving the member to its second position, a pivoted lever having means for engaging and holding said member in its second position, a pivot for said lever supported for rectilinear movement in a direction to permit the member to move toward its first position, a stop for limiting the movement of said pivot in the opposite direction, and condition responsive means for actuating said lever so as to pivot said means on said lever into engagement with said control member for holding it in its second position when a predetermined condition exists and freeing said member for movement to its first position when said condition ceases, and means for biasing said lever towards said condition responsive means and said pivot towards said abutment.

References Cited in the file of this patent UNITED STATES PATENTS 2,567,123 Ray Sept. 4, 1951

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