US2236908A - Movement amplifying snap action thermostat - Google Patents

Description

Ap 1, 1941. I ,w. JACKSON MOVEMENT AMILIFYING SNAP ACTION THERMOSTAT Filed Dec. 12, 19:8

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ATTORNEY.

Patented Apr. 1, 1941.

MOVEMENT AMPLIFYING SNAP ACTION THERMO STAT Wilbur Jackson, .Lynwood, Calif., assignor to Grayson Heat Control, Ltd., Lynwood, Calif., a corporation of California Application December 12, 1938, Serial no. 245,135

6 Claims. (Cl. 236-48) This invention relates to thermostats of the snap action type, and while the principles thereof may be utilized in thermostats adapted for various uses, the invention is here shown for illustrative purposes as embodied in a water heater control thermostat designed to shut off and turn on the fuel to the heater burners in response to variations in the temperature of the heated water in the storage tank.

In snap action thermostats of this general type, such as exemplified in Grayson Patent No. 1,744,- 465, for instance, a motion amplifying lever device has been employed between the thermostatic element and the clicker disk to expedite the snap over action of the disk. The extent of movement imparted to the control valve or other operated element, however, was equal only to the extent of movement of the center of the clicker disk when it reversed from one position to the other. A greater range of movement of the valve is very desirable in devices of this character.

One of the primary purposes of my present invention is to amplify the actual movement of the clicker disk in the transmission of such movement from the disk to the valve or other operable member so that the movement of the valve will be greater than the movement of the disk, thereby lifting the valve a greater distance away from its seat so as to permit an increased volume of fuel to pass the valve.

Another object of the invention is to. insure a quick opening and a quick closing of the valve and to enable accurate operation of the valve against higher fuel pressures than have heretofore been considered good practice.

Another feature of the invention resides in the construction which increases the sensitivity of the thermostat so that the valve will open and close within a shorter range of temperature variations than has heretofore been possible of attainment.-

Another advantage of the invention resides in the fact that the inevitable lost motion in devices of this character is materially reduced even though theindividual parts be made with less detailed accuracy than heretofore required.

Another advantage is that with my present construction, graduation or creeping of the valve at the point or time of closure is largely ellminated so that the dangers of flashbacks, resulting from partial closure of the valve, are obviated.

Other purposes and advantages of my invention should be readily appreciated as the same becomes better understood by reference to the following description when considered in connection with the accompanying drawing.

Referring to the drawing:

Fig. 1 is a longitudinal sectional view through a thermostat embodying my. invention;

Fig. 2 is an enlarged fragmentary view showing the position of the parts when the valve is in open position;

Fig. 3 is a similar view showing the valve in closed position; and

Fig. 4 is a sectional view on the line 4-4 of Fig. 3. 1

bridge 8 of the cylindrical extension is tapped to receive the expansible tube.9 of the thermostatic element, the other member of which is formed by a rod ll of Invar or other materials having a low coemcient of expansion which is adjustably threaded at i2 into the plug l3 closing the end of the tube. This thermostatic element consisting of the expansible and the nonexpansible members is of a well-known type. For adjustment purposes the rod H is equipped with an adjusting lever l4 secured to the rod by a set screw i5 so that swinging movement of the lever will thread the outer end i2 into or retract it from the closure plug iii. The thrust of the rod H is exerted through a cap l6 against a pusher H; A ball i8 interposed between the rod and the cap permits self-centering of the cap and reduces friction. A diaphragm lil'inte'rposed between the cap and the pusher seals the casing against escape of the gaseous fuel around the cap.

Thefuel valve seat 2| is formed on the end of a cage 22 which when threaded-into a tapped opening in the partition wall 23 seats at its inner end against a seal ring 24. I

A valve 25 equipped with a seating face 26 of suitable material is urged into closed position against the seat 2| by an expansion spring 21 interposed between the valve and a closure cap 28. A cylindrical screen 29 may be positioned between the cap and the cage. The stem 3| of the valve disk extends through a guide 32 centrally of the cage, and its inner end is equipped with an adjustable screw 33 by which.

the effective length of the stem may be regulated.

The pusher I1 is guided in the cylindrical skirt 34 of the cage 22, and the annular shoulder 35 spaced marginally inward from the perimeter of the pusher is adapted to engage and actuate the clicker disk 38 from the normal position shown viewing Figs. 2 and 3 of the drawing, of the clicker 'disk has directly contacted the valve stem, and, consequently, travel of the stem would be equal to the distance traveled by the center of the clicker disk in its movement from one extreme position to the other. The initial movement, however, of the clicker disk from the normal position of Fig. 3 toward the. reverse position of Fig. 2 before the snap action of the disk occurred would cause a slight lift of the fuel valve from its seat priorto the full opening by the snap action. This s1ight lift permitted the passage past the valve of a small amount of fuel a within the scope of the invention as defined in the appended claims.

I claim: s

- 1. In a thermostatic device, the combination of a pair of annular fulcrum rings, a plurality of levers fulcrumed between said rings, a clicker disk fulcrumed at its peripheral margin against one of said rings, a thrust member engaging the central portion of the disk and the levers intermedi-- ate their ends, means for actuating the disk, and a member operable by said levers.

2. In a thermostatic device, the combination of a cage having an annular skirt provided with an internal annular shoulder, a fulcrum ring engaging said shoulder, a plurality of radially disposed levers fulcrumed at their outer ends tion amplifying mechanism comprising an annular disk 31 constituting a thrust member having a central stud 38 seated in an opening'lo-v eated at the center of the clicker disk and a pair of levers 39 disposed between the disk 3? and the head 33. The levers as of resilient sheet metal are formed integrally with a ring M adapted to loosely fit within the skirt 8% of the cage 22. A substantial fulcrum is afforded for the outer ends of the levers 39 by a fulcrum ring 42, preferably of wire of suitable size interposed between the levers and the base of the skirt 3%, and a similarfulcrum for the perimeteral margin of the clicker disk 36 is afforded by a wire fulcrum ring 63 interposed between the choker disk and the lever ring ti.

Pressure exerted to the left viewing the drawing upon the pusher I] as the result of contraction of thethermostatic tubular element 9 will cause the clicker disk to reverse its convexity from that shown in Fig. 3 to that shown 1 in Fig. 2 carrying with it the thrust member 31.

'The annular rib at the perimeterof this disk I engaging the levers 39 intermediate their ends will move these levers into the position shown in Fig. 2, thereby quickly and fully lifting the valve from its seat. It will be manifest that by reason of the leverage afforded by the levers 38 and the disk 31, the free or inner ends of levers will move a distance considerably in excess of the movement of the center of the clicker disk. The clicker disk movement is ac- .cordingly amplified, the movement of the fuel valve is increased, and the sensitivity of the increased accuracy in parts.

The fulcrum rings 42 and .43 provide .nonyielding and substantial fulcrums for the am-' plifying levers and for the clicker disk, andbeing of cylindrical shape permit a rolling action of the levers and, of the clicker disk in their flexing movements whichis conducive'to smoothness of operation and to a minimization'ofi'riction between the parts.

While I, have shown and described that preperred embodiment of my invention whereby amagainst said fulcrum ring, a second fulcrum ring engaging the outer ends of said levers, a clicker disk fulcrumed at its peripheral margin against .said second fulcrum ring, a thrust member interto cause the same to amplify the movement transmitted by the disk, and a valve or the like positioned coaxially with said disk and operable by said lever mechanism. s V r 4. In a' thermostatic device, the combination I of a clicker disk, means for actuating said disk,

a plurality of levers fulcrumed in proximity to the periphery of the clicker disk and extendingtoward the center thereof, a valve member or the Lke positioned to be actuated by said-levers, and a. thrust member positioned centrally of the disk between the disk and said levers for transmitting the movement of the center of the disk directly to the levers intermediate their ends whereby said movement is amplified and transmitted to said valve member.

5. In a thermostatic device, the combination of a clicker disk, means for actuating the same, a

disk-shaped thrust member, a lever mechanism,

and an element to be operated, all concentrically arranged in cooperative relation, said thrust member being interposed between said disk and said lever mechanism and movable bodily and equally with the center of the clicker disk, said lever mechanism being operable by said thrust member to amplify and transmit to the element thermostat is improved without the necessity of 4 the production of the to be operated the movement imparted to the thrust member by said clicker disk.

6. A mechanism for transmitting movement from a thermostat to'a member to be operated, comprising, a clickerdisk, means for actuating the clicker disk from the thermostat, a plurality of levers inproximity to and substantially parallel with said disk when in normal position, and

a thrust member of smaller radial dimensions than the disk interposed between said disk and said levers centrally of the disk and movable therewith, said member engaging said levers at an intermediate point on the levers and radially spaced from the center of said disk, whereby said lovers are caused to-amplify and transmit to the member to be opera ed the movement received through said thrust member from said disk.

. WILBUR JACKSON.

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