US2965352A

US2965352A - Snap-acting thermostatic valve

Info

Publication number: US2965352A
Application number: US722876A
Authority: US
Inventors: Charles D Coffey
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1958-03-21
Filing date: 1958-03-21
Publication date: 1960-12-20
Anticipated expiration: 1977-12-20

Description

Dec. 20, 1960 c. D. coFFEY 2,965,352

SNAP-ACTING THERMOSTATIC VALVE Filed March 21, 1958 Jrg4 www \ x 1w v l s INVENTOR.

. T/g', 2 CHARLES D. coFFEY BY l A 7' TOR/VE Y 1. "the ow of gas past the valve seat.

` washer, 24 is welded or otherwise secured to the disc 22 Unit' 2,965,352 SNAP-ACTING THERMOSTATIC VALVE Filed Mar. 21, 1958, Ser. No. 722,876

Claims. (Cl. 251-58) This invention lrelates to control valves and, more particularly, to temperature responsive valves for controlling the ow of gas to a furnace or space heater.

While it is generally old in the art to provide thermostatically controlled gas valves which will snap open to a minimum or partial full ilow position and then modulate between a full on and a minimum flow position and then snap od in the event of the temperature in the space being heated reaching the control point of the thermostat that operates the valve, this invention is directed to a similar type of valve wherein the valve snaps to substantially a full open position and then modulates between the full on and a minimum flow position from which it may snap to its olf position. v

It is another object of this invention to provide a simple mechanical valve actuating means between the valveY head and the thermostatic power means for actuating the valve in a manner indicated above,

Another object of the invention is to provide a lost motion connection between a valve and a valve actuator and resilient means for cooperating with the lost motion means to cause the valve to sequentially snap to its open position, modulate between full on and a minimum flow position and thereafter snap to its closed position from the minimum flow position.

Still a further object of the invention is to provide resilient latching means for holding a valve in its closed position and permitting it to open only when suflicient energy has been stored in a resilient actuator as to cause the valve to move to its substantially full open position upon being released by the resilient latching means and said same latching means preventing the full modulation of the valve back to its off position.

Other objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying drawing wherein:

FigureA 1 is a vertical sectional View taken transversely of the valve body and with portions thereof broken away;

Figure 2 is a vertical sectional view along the line 2--2 of Figure 1; and

`Figure 3 is a fragmentary view partly in cross section, showing the valve assembly just prior to snapping open.

The valve body is made up of two castings, a lower casting 11 and an upper casting 12. The two castings are bolted together by means of bolts 13 with a sealing gasket 14 therebetween. The lower casting has an inlet 15 and an outlet 16 with a partition or wall 17 therebetween. A valve seat member 18 is screwed or otherwise secured to the partition 17 around an opening 19 therein which is surrounded by a sealing gasket 20 clamped `against the partition by means of the valve seat member 18.

The valve head assembly 21 comprises a valve disc 22 adapted to seat on the valve seat 1S and having a depending and inclined skirt portion 23 that serves to regulate A backing disc or Stats Patent and carries a valve stem 25 having a reduced diameter portion 26 that extends through the washer 24 and is headed over against the other side of the washer 24 and in a recess 22a in the disc 22. Slidably mounted on the stem 25 is a frusto-conical sleeve 27 that has an outwardly and downwardly inclined skirt portion 27a of an outside diameter substantially equal to the diameter of the washer 24. A helical compression spring 28 tends to bias the sleeve 27 away from the disc 24 and toward an annular abutment shoulder 29 positioned in an annular groove near the upper end of the stem 25.

Three brackets 30 are secured to the bottom wall of the casting 11 by means of screws 31 while the upper ends of these brackets carry leaf springs 32 that are secured thereto by means of screws 34. The leaf springs have inwardly and downwardly extending arms 33 with vertically extending portions 33a and downwardly and outwardly inclined portions 33b. Portions 33b of the arms engage the upper surfaces of inclined wall 27a of the. sleeve 27 to normally hold the sleeve against the valve head and the valve head against the valve seat, the

spring 28 being of insufficient strength to bias the sleeve upwardly away from the valve disc 24 against the bias of the leaf spring arms.

YThe means for actuating the valve is ,a conventional r temperature sensing bulb 35 connected by a capillary tube 36 to a conventional bellows 37 located in a cavity 38 in the upper portion of the upper casting 12. A cover plate 39 is secured to the upper casting 38 by means of screws 40. Extending through the cover 39 is an adjusting screw 41 that bears against the upper end of the bellows 37 to vary the calibration or control point of the bellows. The lower end of the bellows bears against a head 42 screwed to the upper end of a plunger 43. The plunger extends through an opening 44 in the bottom of the casting 12 and is pivoted at its lower end to a two armed lever 45 that straddles the lower end of the plunger. An O-ring surrounds the stem and is biased against the stern and the upper surface of the bottom wall of the casting 12 by means of a coil compression spring 46 and a spring retaining washer across the O-ring. A heavy coil spring 48 bears at its lower end against the upper surface of the casting 12 and at its upper end against a spring retainer washer 49 positioned between the head 42 of the stem 43 and the light sealing spring 46.

One end of the lever 45 is pivoted on a pivot 50 resting at each of its ends in a recess 51 formed in the upper edges of the casting 11. The pivot is held in position lever 52 is made of stainless steel and has two forked,

ends, one with the forks formed in a loop 52a for the reception of a pivot pin 53. The pin extends through the loops and through a rib 11a formed on the inner surface of the lower casting 11. A screw 53a extends through the top of the rib into engagement with the pin 53 to hold it in position. The other end of the lever 52 has its forks S2b extending through the arcuate grooves 27b in the opposite sides of the sleeves 27a. lt is thus seen that slight upward movement of the plunger 43 by contraction of the bellows 37, will cause considerable upwardmovement of the sleeve engaging ends of the lever 52 due to the motion amplification of the

levers

45 and 52.

Operation Assuming that the valve is installed in a heating, system, with the inlet 15 connected to a source of gas and the outlet 16 connected to a furnace and with thef V elements of the valve in the positions shown in tlreiiguuresA l of the drawing, the heating system would be in a shut down or satisfied condition. Upon a drop in tempera ture of the air surrounding the bulb 35, the bellows 37 will contract permitting the spring 48 to force the' plunger 43 upwardly irV the opening 44. The upward movement of the Yplunger 43 causes the lever 45 to move counterclockwise as shown in Figure l and place a bias on the lever 52l in a clockwise direction around the pivot 53. The spring arms 33 will prevent upward movement of the free end of the lever 52 initially but will then permit or cause the skirt portion 27a. of the sleeve 27 to slide gradually on the surface 33b as the force thereon is increased to the point at which the edge of the skirt 27a reaches the position where the surface 331; joins the vertical surface 33a on the spring arm, whereupon the sleeve will snap upwardly to engage the annular abutment 29 to lift the valve 22 off of the seat 18, the valve moving to substantially its full or maximum open posit-ion. It is to be noted that as the -skirt portion 27a moves up gradually on the surface 33b, the skirt portion will move away from the plate 24 and valve 22 as the spring 28 will hold the valve closed. Only after the lost motion between the sleeve 27 and the abutment 29 has been taken up, will the valve 22 be lifted off of its seat to permit gas to flow through the valve. A large `travel of the valve to its maximum ow position is caused by the unexing of the lever 52 which was bent by its trying to open the valve while it was being held closed by the spring arms 33.

After the initial opening of the valve, placing the furnace into operation and supplying heat to the are surrounding the bulb 3S, the bellows will start to expand and move the valve towards its closed position. As the valve stern is lowered, plate 24 will first engage the upwardly and outwardly inclined surface of the spring arm 33, abo've the vertical surface 33a and will not mo've downwardly any further until after the skirt portion 27a has been lowered a further amount by the lever 52 against the bias of spring 28. Only after a sufiicient force has been built up in the lever 52 by the expansion of the bellows 37, at the minimum flow position of the valve, will an additional movement of the lever 52, under the bias of thebellows, cause the snapping closed of the valve with the skirt portion 27a following.

It is thus seen that this valve provides for the snapping open 'of a Valve to its full open position, to provide the desired initial flow of the gas for ignition purposes, but also modulation of the val've to provide the ow of gas to the furnace in accordance with the need, followed by the snapping closed of the valve from a minimum flow position to prevent flash back in the furnace burners.

While I have disclosed the preferred modification of the valve according to my invention, it is to be understood that various modifications may be made therein without departing from the spirit of the invention. Therefore, the scope of the invention should be determined from the appended claims.

I claim:

l. A valve comprising a valve body having an inlet and an outlet and a valve seat therebetween, a valve head normally resting on said seat but movable away from said seat to an on position, said valve head having a stem thereon with an abutment shoulder at its outer end, a sleeve surrounding said stem and slidable thereon, said sleeve having an inclined peripheral surface with its maximum diameter portion substantially equal to the diameter of said valve head and the axial length thereof substantially less than the distance between said valve head and the abutment on said stem providing a lostmotion connection 'between said sleeve and valve head, resilient means between said valve head and said sleeve tending to separate them, resilient latch means normally engaging saidV inclined peripheral surface to hold said valve head seated on said valve seat but yieldable when said-v sleeve is moved axially away from said sfea't, and

means including resilient means for actuating said sleeve axially.

2. A valve comprising a valve body having an inlet and an outlet and a valve seat therebetween, a valve head normally resting on said seat but movable away from said seat to an on position, said valve head having a stern thereon with an abutment shoulder at its outer end, a sleeve surrounding said stem and 'slidable thereon, said sleeve having a surface engageable with said valve head and having a bearing surface at its periphery and having an axial length substantially less than the distance between said valve head and the abutment on said stern providing a lost-motion connection between said sleeve and said valve head, resilient means between said valve head and said sleeve tending to separate them, resilient latch means having a bearing surface engageable with said bearing surface on said sleeve to hold said valve head seated on said valve seat but'yieldable when said sleeve is moved axially away from said seat, one of said bearing surfaces being inclined with respect to said stem so that the latch means is forced laterally away from said stern as the sleeve moves away from said valve until the distance of the bearing surface' of the latch from the stem is the same distance as the sleeves bearing surface is vfrom the stem, whereupon the sleeve is free 'to move rapidly with no increase in force applied to the sleeve to strike the abutment and lift said valve to its open position, and means for actuating said sleeve axially.

3. In a valve comprising a valve body having an inlet and an inlet chamber and an outlet and a valve seat between said chamber and outlet, the combination comprising a valve head located in said inlet chamber and normally held in a first position but movable away from said first position to a second position, said valve head having a stem thereon with an abutment shoulder at Li-ts outer end, a sleeve of frusto-conical shape positioned in said chamber and slidable on said stem and of shorter length than said stem to provide a lost-motion connection with said valve head, said sleeve having an axial length substantially less than the distance between said valve head and the abutment on said stem, resilient means between said valve head and said sleeve tending to separate them, latch means normally engaging said sleeve to hold said valve head seated on said valve seat but laterally yieldable when said sleeve is moved axially away from said seat to permit said sleeve to move rapidly once it clears said latch means to pick up said valve head, and means for actuating said sleeve axially.

4. In a valve comprising a valve body having an inlet and an outlet and a valve seat therebetween, the combination comprising a valve head normally resting on said seat but lmovable away from said seat to an on position, said valve head having a stem thereon with an abutment shoulder at its outer end, a sleeve surrounding said stem and slidable thereon, said sleeve having an inclined peripheral surface with its maximum diameter portion substantially equal to the diameter of said valve head and the axial length thereof substantially less than the distance between said valve head and the abutment on said stem, resilient Imeans between said valve head and said sleeve tending to separate them, resilient latch means normally engaging said inclined peripheral surface to hold said valve head seated on said valve seat and said sleeve away from said abutment but yieldable when said slee-ve is moved axially away from said seat to free said sleeve to move Irapidly toward `said abutmentto pick up said abutment and to open said valve, and means including resilient means for actuating said sleeve axially.

5. A valve comprising a valve body having an inlet and an outlet and a valve seat therebetween, a valve head normally resting on said seat but movable away from said seat to an on position, said valve head having a stem thereon with an abutment shoulder at its outer end, a sleeve surrounding said stem and slidable thereon, said sleeve having an inclined peripheral surface with its 5 maximum diameter portion substantially equal to the diameter of said valve head and the axial length thereof substantially less than the distance between said valve head and the abutment on said stem, resilient means between said valve head and said sleeve tending to separate them, a plurality of resilient latch means spaced around said valve head and normally engaging said inclined peripheral surface to hold said valve head seated on said valve seat and said sleeve away from said abutment but laterally yieldable under the bias of said sleeve 10 when said sleeve is moved axially away from said seat to free said sleeve to move `rapidly toward said abutment to piek up said abutment and to open said valve, and means for actuating said sleeve axially.

References Cited in the le of this patent UNITED STATES PATENTS 2,437,468 Hunter Mar. 9, 1948