US3417918A

US3417918A - Gas control snap acting and modulating valve assembly

Info

Publication number: US3417918A
Application number: US647766A
Authority: US
Inventors: Elmer E Wallace
Original assignee: Controls Company of America
Current assignee: Controls Company of America
Priority date: 1967-06-21
Filing date: 1967-06-21
Publication date: 1968-12-24
Anticipated expiration: 1985-12-24
Also published as: NL6808840A

Description

Dec. 24, 1968 E. E. WALLACE 3,417,913

GAS CONTROL SNAP ACTING AND MODULATING VALVE ASSEMBLY Filed June 21. 1967 United States Patent O 3,417,918 GAS CONTROL SNAP ACTING AND MODULATING VALVE ASSEMBLY Elmer E. Wallace, Fullerton, Califi, assignor to Controls Company of America, Melrose Park, Ill., a corporation of Delaware Filed June 21, 1967, Ser. No. 647,766 1 Claim. (Cl. 236-48) ABSTRACT OF THE DISCLOSURE The manually actuated knob is rotated to adjust the compound leverage actuated by the bellows to impart movement to the valve assembly with the initial movement operating a snap disc to open a valve for low flow as determined by the adjustment of a valve in the bypass. Continued movement flexes a spider to gradually actuate the main valve.

BACKGROUND OF INVENTION There are two general classes of gas controls, one controls the flow of gas to the burner so that it is either on or ofl. The other class modulates the flow to more closely approximate the heat load. In the latter classification provision is generally made for initiating or terminating the flow with a snap action of the valve mechanism so that the minimum flow rate will not be below that considered safe for operation of the burner. In the United States the low flow rate has generally been considered properly held to about 50% of the full flow rate. In Europe, however, the low flow rate can be as low as To obtain such a low flow rate it has been customary to open a snap acting valve to establish a flow path which can be accurately restricted to obtain the desired low rate. Continued actuating movement imparted to the valve assembly after opening the snap acting valve will then act to gradually open the principal or modulating valve.

In the prior art there have been many solutions to the foregoing but these have generally required a rather substantial movement to be imparted to the valve assembly to obtain both actions and the valve assembly itself has generally been somewhat diflicult to assemble.

SUMMARY OF INVENTION The actuating pin which is moved by the temperature responsive mechanism acts on a rigid spider vertically movable inside a carrier to act on a snap disc which, when it snaps over center, will actuate the snap acting valve to move it from its seat which is carried by the carrier. The carrier is supported on a flexible diaphragm or bellows assembly permitting vertical movement of the carrier. After the snap disc is snapped over center, the rigid spider, in effect, goes solid with respect to the carrier, the lower end of which operates on a flexible spider providing a motionmultiplying leverage to actuate the stem of a modulating valve vertically slidable in a cup-like support in which the carrier is free to move. The cup-like support together with the modulating valve, the carrier, the diaphragm, and the snap valve can all be assembled as a subassembly and merely placed into the valve housing. The assembly costs with this arrangement are very low and there are no critical dimensions to be maintained in the valve actuating direction wtih the result that there is no need for adjustment after assembly. Due to the motion-multiplying effect of the snap disc and of the modulating spider, a great amount of movement can be imparted to both of the valves with a relatively minor amount of movement being imparted to the assembly. This reduces the size requirements of the actuating bellows in the temperature responsive mechanism.

Patented Dec. 24, 1968 ice The single figure has been simplified in some respects from the actual working construction but in connection with the snap and modulating valve assembly is as manufacturers contemplate it.

DESCRIPTION OF PREFERRED EMBODIMENT For simplicity only a fragmentary valve housing 10 has been shown. This is provided with an inlet 12 and it will be understood that gas flow into inlet 12 would normally be pressure regulated and there would also be provision ahead of the present valve arrangement for interruption of flow in the absence of pilot flame, etc.

In the cavity 14 there is a seat 16 for modulating valve 18 having a stem 32 projecting through the lower end of support 20 for engagement by the inner ends of the finger portions 22 of spider 24. The outer (ring) portion 26 of the spider is engaged by the lower end of carrier 28. Spring 30 biases the valve away from support 20 towards its seat with the valve position being determined by the point of engagement of the spider 24 with the head of the valve stem 32. The cup-like support 20 is placed in the cavity 14 as a complete subassembly with the valve 18 mounted as described and with the carrier 28 inside the support 20. The flexible diaphragm 34 is clamped on the carrier by wire ring clamp 36 and has an upper peripheral seal portion which is adapted to seal with respect to gasket 38 under the cover 40. The carrier 28 includes a seat 42 against which snap valve 44 seats. The valve has a stem 46 projecting through the center of the carrier with the spring 48 acting against the stem head 50 to urge the valve in the closing direction. In side the upper end of the carrier there is a small ring 52 over which the snap disc 54 is mounted so that it will tend to fulcrum about the ring 52. At the top of the carrier there is a spider 56 having a depending ring-like actuating edge 58 resting on the snap disc 54 inside of the pivot ring 52.

As the spider 56 is moved downwardly it will stress the snap disc 54 until it snaps over center about the pivot ring 52 so that the inner end of the snap disc will strike the stem head 50 and move valve 44 off seat 42. This, then, will allow flow from inlet .12 through the holes 60 in the lower portion of the support past the now opened valve 44 and through the ports 62 and thence out of the ports 64 in the spider. This flow will then pass through conduit 66 past the adjustable valve 68 to conduit 70 which leads into outlet 72 leading to the main burner.

Continued downward motion imparted to the spider will then cause carrier 28 to move downwardly so that its peripheral actuating edge 74 will act against spider 24 to flex the spider about the pivot 76 formed in the lower portion of the support to thereby act on the head 78 of valve stem 32 to move the valve 18 upwardly away from its seat 16. Since the minimum flow to the main burner is established through the

bypass conduits

66 and 70 the additional opening imparted to valve 18 will constitute flow in excess of the minimum rate. The minimum rate is set by adjustment of valve 68 which, it will be noted, may be fully closed so as to limit the low flow to that which can pass through orifice 80.

The entire assembly of the valve 18 and support 20 along with the carrier and diaphragm can be assembled as a subassembly and merely dropped in the cavity 14. It will be noted that there are not critical vertical dimensions and, hence, there is no need for fine adjustment after assembly. 7

Motion is imparted to the spider 56 by means of rod 82 passing upwardly through the housing cover 40 to be actuated by secondary lever 84 through the medium of adjusting screw 86. Primary lever 88 is pivoted at 90 on top of the valve housing. Spring 92 biases the primary lever 88 in a counterclockwise direction about pivot 90 so that it will bear against the actuating pin 94 carried by bellows 96. The bellows pressure varies in accordance with the temperature at feeler bulb 98 which is placed in the ambient air, the bulb being connected to the bellows by means of capillary tubing 100. The primary lever 88 is provided with upstanding ears 102 between which a pivot pin 104 is mounted and the secondary lever 84 is biased by spring 106 against pin 104 so that it, in effect, wants to follow the motion of the pin. The left end of the secondary lever 84 rides on the underside of cam 108 carried on shaft 1.10 which is actuated by knob 112. Knob 112 is rotated to rotate the cam and, hence, determine the initial position of the pin 82 with respect to the valve assembly at a given temperature. As the pressure inside bellows 96 decreases (temperature at the bulb decreases) the spring 92 causes the primary lever 88 to follow the movement of the bellows pin 94 downwardly. This, then, takes the pivot pin 104 downwardly which, in turn, will rock the secondary lever about its point of contact with the cam and move the pin 82 and spider 56 down. This will first open the snap acting valve 44 and if continued downward motion is imparted the modulating valve 18 will also open. As the temperature around the feeler bulb 98 increases, the pressure will increase resulting in the reverse motion being imparted to the actuating pin 82 and this will then let the spider 56 and carrier 28 start moving upwardly to first close the modulating valve and then if continued upward motion of actuating pin 82 occurs finally the force of spring 48 acting on stem head will be enough to overcome the snap disc 54 and cause the valve 44 to snap closed to terminate all flow to the main burner.

I claim:

1. A gas control including:

a housing having an inlet and an outlet,

a valve seat in the housing,

a fixed generally cup-shaped support in the housing,

a modulating valve carried by the support for movement toward and from the seat, 7 p

a carrier nested inside of and movable with'respect to the support,

a flexible seal interconnecting the carrier and the support, i

a spider having a fulcrum on the support and responsive to movement of the carrier relative to the support to actuate the modulating valve with a motion multiplying effect,

a port in the carrier,

a snap valve carried by the carrier for movement relative thereto for controlling flow through the carrier port,

a snap disc carried by the carrier and operative to actuate the snap valve,

and temperature responsive means connected to the snap disc through a motion multiplying leverage and actuating the snap disc in accordance with temperature so initial movement in the valve opening direction opens the snap valve first and continued movement gradually opens the modulating valve.

References Cited UNITED STATES PATENTS 2,702,052 2/1955 Grayson 236-48 2,889,990 6/1959 Loveland 236-48 WILLIAM J. WYE, Primary Examiner.