Manually Reset Safety Control

Abstract

A 100 percent safety shutoff gas valve comprising a biased closed main valve, a biased closed pilot valve, a thermoelectric power unit for holding the valves open but incapable of opening them and a plurality of pushbutton actuators that are sequentially actuated to first open the pilot valve and reset the power unit for energization by a pilot burner heated thermocouple and, thereafter, actuate another pushbutton to open the main valve. The valves are adapted to be closed either by the occurrence of a pilot burner flame failure, which deenergizes the magnet, or by depressing a third button to directly close the pilot valve and indirectly close the main valve by tripping a latching mechanism. The pushbuttons have an interlock arrangement whereby depressing of one pushbutton causes retraction of a previously actuated pushbutton.

Description

MANUALLY RESET SAFETY CONTROL

Safety pilot valves, which generally perform the end functions performed by this invention, are well-known in the art so the invention to be defined in detail below obviously lies in the particular combination and arrangement of valves and their actuating elements to function in a particular manner.

FIG. 1 of the drawing schematically illustrates the invention as it would appear in a vertical sectional view through the valve assembly;

FIG. 2 illustrates the position of an interlock latching means for the push buttons which is located on the backside of the valve illustrated in FIG. 1;

FIG. 3 is a sectional view of the pushbutton and interlock latching means taken along line 3-3 in FIG. 1;

FIG. 4 illustrates the mechanism and valve positioning of the invention in the positions the elements assume when the valve is being reset;

FIG. 5 illustrates the arrangement of the elements after the magnet has been energized and the main valve opened; and

FIG. 6 illustrates the position the elements assume upon a pilot burner failure.

Referring to FIG. 1 of the drawing, the valve body is generally designated by the reference numeral 11 and has a threaded inlet 12, a main burner outlet 13, a pilot burner outlet 14 and a plurality of plunger openings 15, 16 and 17 in an upper wall thereof and a cavity 18 with an aperture 19 also in the upper wall thereof.

A main gas valve 20 has a valve stem 21 that slides vertically in a bearing or guide member 22. The lower end of the stem 21, which extends below the guide 22, has a head portion 23 and a spring retainer cup 24 for the reception of one end of a coiled compression spring 25 extending from the lower wall of the valve body and the head 23 of the valve stem. The valve 20 is normally held closed against the valve seat 26 but is adapted to be actuated to its open position, against the bias of spring 25, by means of a valve actuator in the form of a lever 27 pivoted at one of its ends on a pivot 28. The other end of the lever is biased in a clockwise direction about the pivot 28 by means of a comparatively light tension spring 29 engaging the other end of the lever. Pivoted on the lever 27 by a pivot 30, is a latch member 31 with a transversely extending portion 31a that is adapted to engage the valve stem 21 above the head 23. It is resiliently urged into that position by means of a leaf spring (not shown) or by a coil spring 32. Also extending from the latch member 31 is an arm 31b which serves as an abutment 31 to be engaged by a resetting lever 33.

A point valve 34 is normally biased into seating engagement with a valve seat 35 by means of a coiled compression spring 36 and has a stem 37 that extends through the valve seat and to a position spaced a short distance from the lever 33. Located in the cavity 18 is a condition responsive means in the form of a conventional electromagnet 38 secured therein by having a threaded sleevelike portion 39 extending through the aperture 19 and held therein by means of a nut 40. An armature (not shown) of a conventional construction, is located within the electromagnet 38 and has a stem 41 extending out of the bottom thereof and into engagement with the end of the lever 33. A strong compression spring 42 normally holds the armature away from the magnet (not shown) but the armature is adapted to be held by the electromagnet, against the bias of this spring, when it is energized by a pilot burner heated thermocouple T. The lever 33 is pivoted intermediate its end on a separate pivot or on the same pivot 28 for the lever 27. The other end of the lever 33 is adapted to engage the abutment 31b of the latch 31 to disengage the latch 31 from the head 23 of the main valve. This occurs when the armature drops away from the magnet when the valve is in the open position or when the lever 33 is otherwise moved clockwise. The lever 33 is caused to follow the movement of the armature stem 31 by means of a spring 43 which is strong enough to overcome the spring 36 but not strong enough to overcome spring 42.

The value mechanism is illustrated in the "off" position in FIG. 1, wherein both the main valve and pilot valve are closed and the armature is separated from the deenergized magnet. A plunger 44 extends through opening 16 and is retained therein by means of a split washer 45, located in an annular groove 44a in the plunger, and by a compression spring 47 extending between a push button 48 secured to the upper end of the plunger 44 and a washer 46 loading an O-ring sealing means 49. Downward movement of the plunger 44 will cause engagement of the lower end of the plunger with lever 33 to move the armature into seating engagement with the electromagnet and lift the pilot valve 34 off from its seat, as illustrated in FIG. 4. This downward movement of the plunger 44 and push button 48 will cause a pin 48a, extending from the front wall thereof, to slide along a cam surface 50a of a slidable plate or interlock latch member 50, to cause a latch shoulder 50b to disengage from an abutment 51b on a button 51 connected to the top of a plunger 52. This movement of the interlock latch is against the bias of a compression spring 53. The inward movement of the button 48 also positions an abutment 48b (see FIG. 2) under a latch 56c on a second slidable plate or interlock latch 56 which, due to the fact that the button 51 has been released to its upper position under the bias of spring 54, enables the spring 55 to move the interlock latch 56 to the right as viewed in FIG. 2.

The plunger 52 is sealed against leakage by means of an O-ring seal 57 by being compressed against the plunger by means of spring 54. Plunger 52 is adapted to rotate the lever 33 clockwise about its pivot to disengage the latch 31 and to permit the pilot valve to close regardless of whether or not the armature is being held by the electromagnet.

To provide for the opening of the main valve following the opening of the pilot valve and the resetting of the armature, a plunger 58 extends through the opening 15. It is supported therein and sealed against leakage by an O-ring seal 59 in a manner similar to the previously described plungers. An "on" button 60 on the plunger 58 is biased outwardly by means of a coil compression spring 61 which normally holds the plunger in the position shown in FIG. 1 of the drawing. It will be noted that the tension spring 29 normally holds a shoulder portion 27a against the lower end of the plunger 58 so as to cause the lever 27 to follow the movement of the plunger 58. Depression of the "on" button to the position illustrated in FIG. 5, not only rotates the lever 27 counterclockwise, moving the latch 31 and the valve 20 to their open positions, but also causes a pin 60a to move along cam surface 50c to deflect the interlock plate 50 to the left and an abutment 60c to move along cam surface 56a to position 60b under 50d and to disengage the "pilot" button 48 from its latching engagement with abutment 56c and to permit the button to return to its fully retracted or outermost position, respectively. This would then free the lever 33 to be moved clockwise about its pivot in the event there should be a pilot burner flame failure, resulting in deenergization of the magnet and drop out of the armature, to provide safety shutdown. This last mentioned condition causes the elements of the valve to assume the position shown in FIG. 6 of the drawing. It will be noted that while the main valve 20 is in the closed position, in FIG. 6 of the drawing, the "on" button is still being held in its depressed position due to the latching of the abutment member 60b under the latch 50d. Therefore, before the burner can again be placed in operation, it will be necessary for the "off" button to be depressed to cause the "on" button to be raised, through actuation of the interlock latch slide members, to raise the lever 27 to the position wherein the latch member 31 can again be positioned above the head 23 on the main valve stem.

From an understanding of the construction and the arrangement of the parts described above, the operation of the valve is deemed to be obvious but may be briefly described as follows. Depression of the "pilot" button causes the "off" button to be released to return to its uppermost position while simultaneously rocking the lever 33 to reset the armature and to open the pilot valve 34. Releasing the pilot button 48 will cause the plunger 44 to return approximately half way between its resetting position, illustrated in FIG. 4 of the drawing, to the dotted line position where the abutment 48b will engage the latch shoulder 56c. While this partial return of the "pilot" button to the dotted line position may cause a slight return of the pilot valve toward its valve seat, the spring 43 will cause the pilot valve to stay in an open position. With the armature being held to overcome the spring 42, the "on" button may then be depressed to unlatch the "pilot" button and pivot the lever 27 counterclockwise to open the main valve 20 through the latch member 31. The pilot and main burners will then continue to burn until either the "off" button is depressed to close the pilot value and trip the latch member 31 to close the main valve or the magnet becomes deenergized to cause drop out of the armature to accomplish this same function.

Claims

I claim:

1. A manually reset safety control, embodiment embodying a valve body having an inlet, a main outlet and a pilot outlet, a main biased-closed fuel flow control valve and a pilot biased-closed fuel flow control valve and a condition responsive means for holding the valves open but incapable of opening them, comprising; a first valve actuator is said valve body, latch means operably connected to said first valve actuator and said main valve and detachable from one of them, a first motion transmitting means having a first portion thereof operably connected to said first valve actuator and another operable portion, a second valve actuator in said value body, means adapted to be actuated by said condition responsive means for biasing said second valve actuator in a direction to close said pilot valve and to unlatch said latch means from said main valve when an unsafe condition arises and requiring manual resetting to move said pilot valve to its open position, a second motion transmitting means having one portion for actuating said second valve actuator to reset said condition responsive means and open said pilot valve and another operable portion, a third motion transmitting means having a portion for actuating said second valve actuator to close said pilot value and unlatch said main valve and having another operable portion thereof, and interlock latch means arranged to selectively cooperate with said another operable portions for selectively latching one of said first, second or third motion transmitting means in its "on" "pilot" or "off" positions, respectively, said interlock latch means being so constructed and arranged that when one of said motion transmitting means is actuated the previously actuated one is released and returns to its unactuated position.

2. A manually reset safety control as defined in claim 1 wherein said second motion transmitting means is arranged to latch in a position intermediate its unactuated position and its resetting position.

3. A manually reset safety control as defined in claim 1 wherein said motion transmitting means include pushbuttons which are constructed to form part of said interlock latch means.

4. A manually reset safety control as defined in claim 3 wherein said first, second and third motion transmitting means are plungers with said pushbuttons mounted thereon and arranged in a common plane and part of the interlock latch means includes a pair of slidable latch plates extending across the sides of said pushbuttons.

5. A manually reset safety control as defined in claim 1 wherein said condition responsive means is a thermocouple energizable electromagnet and said valve actuators are levers.

6. A manually reset safety control as defined in claim 5 wherein said first lever is pivoted at one of its ends and said latch means is pivoted on said first lever intermediate its ends.

7. A manually reset safety control as defined in claim 1 wherein said valve actuators are levers and said latch means is pivoted on said first lever and said levers are mounted on a common pivot.