US1874661A - Thermostat - Google Patents

Description

0, 93 s. P. VAUGHN 1,874,661

THERMOSTAT Filed Sept. 15, 1930 1N VEN TOR.

Patented Aug. 30, 1932 UNITED STATES PAT ENT OFFICE SIDNEY IP. VAUGHN, OF THE UNITED STATES NAVY, ACKERMAN, MISSISSIPPI, ASSIGN- OR TO GRAYSON HEAT CONTROL, INQ, 01E LYNWOOD, CALIFORNIA, A CORPORATION OF CALIFORNIA rnnauosre'r Application filed September 15, 1930. Serial No. 482,141.

This invention relates to thermostatic snap-mechanisms generally, but more particularly to thermostatic snap-valves adapted to the requirements of water heaters, ovens,

and the like.

' Gas burners are usually designed to operate most efiiciently on a predetermined quantity of gas at a predetermined pressure, and it has been found that greater fuel economy is obtained in a system employin a thermally controlled valve if the valve is opened and closed with a quick action, than if the valve is permitted to open and close slowly as the thermal-responsive element is gradually heated or cooled.

The principal object of my invention is to provide a simple, reliable and inexpensive snap-action thermostat, one in which the snap action of a convexo-concave disc of go spring material is amplified by means of a fulcrum lever cooperating intermediate its ends with the disc and transmitting movement at the free end thereof, whereby to secure any desired travel of the valve or other element to be operated.

The foregoing, together with such other objects as may hereinafter appear, or, are incident of my invention, I obtain by means of a construction described herein and illustrated in its preferred form in the accompanying drawing wherein:

Fig. 1 is a central longitudinal section through a thermostatic snap valve for a water heater made in accordance with my invention and shows the valve closed.

Fig. 2 is a vertical sectional view on line AA Fig. 1 looking toward the valve body.

Fig. 3 is the same view asthat in Fig. 1 showing the valvein an open position.

Figs. 4 and 5 illustrate modified forms of the snap mechanism illustrated in Figs. 1, 2 and 3.

Like numerals refer to like parts throughout the several views.

Referring to the drawing the apparatus includes a valve body 1 connected by a yoke 2 to a plug 3 which is adapted to screw into a nipple 4 secured to a tank 31 or other apparatus containing the fluid to be heated. The valve body 1 has a fuel supply inlet 5 and an outlet 6 leading to the burner. Communication between the inlet and outlet side of the valve body is established by means of a valve 7 carried by a stem 8 extendingthrough the body in the direction of the plug 3 and which is normally yieldingly held in a closed position by a helical spring 29 which engages the valve and is supported in the bore of a removable cap 9 threaded into the valve body 1 with the bore disposed concentrically with the valve.

The plug 3, which attaches the valve assembly to the boiler 31 carries the usual thermostatic elements which extend in the fluid to be heated. In this case the thermostatic elements comprise a tube 10, preferably a copper tube or other metal tube having a high coefficient of expansion, having one end secured to the plug 3 and its free end extending into the fluid to be heated, anda rod 11 of invar or other metal or substance hav ing a low coeflicient of expansion, passing through the tube 10 and having one end screwed into a plug 12 secured watertight in the free end of the tube 10. The thermostatic elements are preferably disposed concentrically in relation to the valve stem 8 to obtain a more compact arrangement. It is evident that expansion and contraction of the tube 10 results in endwise movement of the invar rod 11. This movement is amplified and utilized to open and close the valve 7 quickly through the intermediary of a compound lover system including a resilient lever 13 actuated by the free end of the rod 11 and supported at its fulcrum end ill tile yoke 2 by a pin 14, and a comparatively non-resilient lever 15 actuated by the free end of the resilient lever 13 and supported at its fulcrum end by a pin 16 between a pair of ears 17 ex tending from the valve body. Both levers are of the third class having the actuating force applied between the fulcrum and the load. The free end of the non-resilient lever 15 actuates the valve stem 8. Any degree of amplification may be attained with this arrangement, and in order to transmit the amplified movement of the rod -11 to the valve 7 with a snap action, a normally convexo-concave spring metal disc 18, which will collapse 100 to a concavo-convex form with a snap movement when pressure is applied to the convex side and which will re ain its normal convexo-concave form w en the pressure is removed, is utilized to increase the load on and retard the movement of the non-resilient lever 15 until the force exerted by the resilient lever 13 is suificient to overcome the resistance of the disc and cause it to snap past dead center into a concavo-convex form as illustrated in Fig. 3. The ed e of the disc is supported on an annular s oulder 20 in a recess 19 formedin the valve body .1 between the non-resilient lever 15 and the valve body outlet 6 with the center of the normally convex side of the disc in contact with an adjustment screw 21 carried by the non-resilient lever 15 between the fulcrum and the free end of the lever. The free end of the lever, it will be observed, is in contact with the valve stem 8. The disc 18 should be sufiiciently stiff to exert a load moment on the lever 15 greater than the load moment exerted by the valve, so that the lever 15 will force the valve open with a snap or quick movement when the disc collapses to a concave-convex form. The force required to cause the disc to collapse to a concavoconvex form is very much greater at the beginning of the collapse than at the end of the collapse, decreasing very rapidly as the center of the disc approaches its cord center line. There should be, however, suflicient tensile stress set up in the disc to cause it to regain its normal convexo-concave form when the force is removed. The resilient lever 13 is provided to amplify and store up the potential energy necessary to cause the disc to collapse to a full concavo-convex form when it begins to collapse and to open the valve at the same time with a snap action. The resilient lever should be sufficiently stiff as to require the minimum end movement of the rod 11 to open and close the valve with a snap action, but not so still as to prevent the disc collapsing with a snap action.

A stop 27 is provided in the valve body to limit the movement of the non-resilient lever 15, thus preventing any abnormal movements that would strain the disc 18 to such an extent as to prevent it regaining its normal convexo-concave form when the force collapsing the disc is removed. The resilient lever 13 will allow any abnormal end movements of the rod 11 which may take place due to abnormal changes in temperature.

In Figs. 1 and 2 the resilient lever 13 is shown in the form of a flat spring, but it may take the form illustrated in Fig. 4, that is,

thicker at its fulcrum end than at its free resilient end, so that the end movement of the rod 11 may be amplified before causing the resilient portion of the lever to flex.

In order to take up lost motion in the lever system and to provide a means for regulating the temperature, the rod 11 is screwed into the plug 12 in the end of the tube and the end movement of the rod 11 is adjusted by swinging a lever 22, secured to the rod, relative to a dial 23, graduated in any suitable manner as for example"HotWarmCold. An adjustment screw 21 is provided in the non-resilient lever to take up lost motion between the lever and the disc 18, and to regulate the throw of the lever with reference to the valve stem 8. In Fig. 4 is illustrated a modified form of the amplification lever system in which the resilient lever 13 is thicker at its fulcrum end than at its free end which is resilient. With this form of resilient lever the end movement of the rod 11 is amplified to flex the resilient portion of the lever through a greater are than would occur if a flat spring lever of the same thickness throughout were used, thus makin the system more sensitive to temperature 0 anges. Instead of adjusting for temperature as illustrated in Fig. 1, an adjustment screw 28 for temperature regulation is embodied in the thick end of the resilient lever against which the thermostat rod 11 presses. A second adjustment screw 24 to take up lost motion is carried by the non-resilient lever 15 against which the free' end of the resilient lever 13 presses. Instead of placin the snap disc 18 in a recess formed in the va ve body as illustrated in Fig. 1, it may be carried in a recess 19 formed in an extension of the non-resilient lever 15 with the center of the convex side of the disc pressing against an adjustment screw 21 screwed in the body of the apparatus. The action is the same as that described for the assembly illustrated in Figs. 1 and 2. From theabove, it is apparent that the disc may be placed in any convenient place, either in the lever or in the valve body. The only requirement is that it be placed in such a manner with relation to the levers and valve stem that the snap action will be amplified before opening the valve.

In Fig. 5 is illustrated another modified form of lever amplification in which a single resilient lever 13 of the 3rd class is used to actuate the valve or an electric switch. With this method the force is applied between the fulcrum and the load and the disc 18 is applied on the side opposite the force and between the point of force and the point of load. When a force is applied by the movement of the rod 11 the lever flexes more and more as shown by the dotted lines 25 until the pressure on the disc causes it to collapse to a concavo-convex form, at which time the free end of the lever Will snap into the position indicated by the dotted lines 26, thereby open ing the valve or operating an electrical switch, whichever may be used.

In operation assume that the valve 7 is closed as illustrated in Fig. 1, and that the thermostat rod 11 moves slowly inwardly due;

to a reduction in temperature and "presses against the resilient lever 13. The lever 13, being resilient, flexes more and more the farther the inward movement of the rod 11, builds up potential energy in the lever and transmits it to the disc 18 through the nonresilient lever 15. When the pressure on the disc is sufficient to cause it to collapse to a concavo-convex form, the non-resilient lever, due to the stresses in the resilient lever 13, will snap against the valve stem 8 and open the valve 7 as illustrated in Fig. 3. The opening of the valve 7 permits fuel to pass to the burner where it burns and heats the fluid to be heated. As the temperature of the fluid rises, the thermostat tube 10 expands and causes the end of the thermostat rod 11 to move back, thus relieving the pressure on the lever system and'the disc 18. When the pressure against the disc is relieved suficiently,

. the disc will snap back to its normal convexoconcave form and force the non-resilient lever back to its original positlon, thus permitting the valve to close, due to the action of the helical spring 27 pressing on the valve.

Tam aware that there are similar types of thermostatic valves in which clicker discs and resilient levers are used to obtain a similar action, but in such devices the valve stems are actuated direct by the clicker disc, and the travel of the valve is limited to the throw of the disc, which in most cases is very small, thus requiring a large valve to obtain the required gas flow. It often happens with such arrangements that the clicker disc is strained and does not regain its normal convexo-concave form, which prevents the valve closing and shutting off the fuel supply. In the arrangement disclosed in this invention the valve may be actuated to any desired opening and should the disc become strained or fail to regain its normal convexo-concave form, the-valve will close when the force acting on the lever system is removed. This very important distinguishing feature forms the basis for this invention and should not be confused with the action obtained in valves actuated directly by the clicker disc or over-center spring. Another point to bear in mind is that the lever amplification in valves operated directly by the clicker disc is limited to the travel of the center of the disc from a full convexo-concave form to a full concavo-convex form, and that to obtain a large amplification the disc must be made proportionately large, whereas, in my invention any degree of amplification may be obtained and any size disc may be used, due to the fact that the disc does not operate the valve, but is merely used to cause the nonresilient lever operating the valve to move with a snap action.

It is believed that the foregoing description conveys a clear understanding of the objects and advantages of my invention. While I have illustrated and described the application thereof to valves and electric switches it should be understood that there are numerous other possible applications. All legitimate modifications and applications of my invention are therefore to be construed as coming within the scope and spirit of the appended claims.

\ I claim:

1. In a thermostatic device, the combination with a thermostatic element adapted to move upon temperature change, and a device to be moved according to temperature change, of a resilient lever system intermediate said element and said device for amplifying the movement of the element and operating said device, said resilient lever system comprising a resilient lever actuated by the thermally expansible member, and a comparatively nonresilient lever actuated by the resilient lever and arranged to operate the device, and means cooperating with the non-resilient lever to cause the latter to move with a snap action in operating the device, said means comprising a snap action, over-center element of spring material actuated by the said non-resilient lever and adapted to snap over center under pressure of the lever thereon and further adapted to snap back to its normal position when the pressure of said lever thereon is relieved.

2. Adevice as set forth in claim 1 wherein the non-resilient lever is pivoted at one point and at another point thereof spaced a predetermined distance from the pivot is arranged to communicate movement to the device, and wherein the snap-action element is actuated by said lever at a point intermediate the pivot point and the other point.

3. A device as set forth in claim 1 wherein the non-resilient lever is pivoted at one point and is so disposed with relation to the device to transmit movement to the latter at another point spaced a predetermined distance from the pivot point, and wherein the snap action element is actuated by the lever at a third point spaced another predetermined distance from the pivot pointfiwhereby to maintain a predetermined ratio between the movement of the device and the snap-action movement of the element.

4. In a thermostatic device, the combination with a substantiallynon-resilientthermostatic element adapted to move upon temperature change, and a device to be moved according to temperature change, of a resilient lever system intermediate said element and said device for storing up energy therein with the movement of the element to operate said device, said system comprising one or more levers operated by said element and through which the movement of said element is amplified, the terminal lever of the system being pivoted at one end and disposedso as to directly operate the device at its other end, and means operated by said lever to cause the described, the combination with a thermostatic element adapted to move upon temperature change, of a device to be operated according to temperature change, a snap-action over-center element of spring material, a movement amplifyin lever pivotally supported at one end an traversing said overcenter element intermediate its ends and having its free end arranged to communicate movement to the device, the lever appl ing ressure to the over-center element and be- 1ng dependent for its movement upon the snap action of the over-center element and being arranged in such snap action to give abrupt amplified movement to the device, said lever bein operatively connected near its pivot with t e thermostatic element.

6. In a thermostatic device ofthe character described, the combination of a body member, a tube having a rod mounted therein to form a thermostat, the tube being fixed on the body and arranged to communicate endwise movement to the rod in the event of temperature change, a valve or other device to be operated according to temperature change mounted in one portion of the body, said valve having a stem for operating the same projecting from that portion of the body, spring means normally holding the valve closed, a spring diaphragm disc of substantially convexo-concave form supported loosely about its outer edge in another portion of said body with the center thereof spaced laterally from the projecting end of the valve stem, a resilient movement amplifying lever system operated by said rod, the terminal lever of said system being pivotallv supported at one end on the last mentione portion of the body and extending past the central portion of the disc and having its free end disposed to communicate movement to the projecting end of the valve stem, the lever applying pressure to the central portion of the disc and being dependent for its movement upon the sna action oi the disc and being arranged in suc snap action to give abrupt amplified move ment to the valve stem, the resilient lever system serving to amplify the movement of the rod to force the disc over dead center to concave-convex form.

7. In a thermostatic device of the character described, the combination of a body member,

and arranged to communicate endwise movement to the rod in the event of temperature change, a valve or other device to be operated according to tem erature change mounted in one portion of t e body, said valve having a stem for operating the same projecting from that portion of the body, sprlng means normally holding the valve closed, a spring diaphragm disc of substantially convexo-concave form supported loosely about its outer edge in another portion of said body with the center thereof spaced laterally from the projectin end of the valve stem, a movement ampli yin lever pivotally supported at one end on thfiast mentioned portion of the body and extending past the central portion of the disc and having its free end disposed to communicate movement to the projecting end of the valve stem, the lever being dependent for its movement upon the snap action of the disc and being arranged in such snap action to give abrupt amplified movement to the valve stem, and a second movement amplifying lever pivoted on the body member adjacent the thermostat and having the rod engaging the same intermediate its ends, the free end of said lever cooperating with the other lever intermediate the ends thereof to communicate movement thereto, at least one of said levers I being resilient whereby to permit of snap action of the disc in the cooperation of said levers therewith.

8. In a device of the character described, the combination With a thermostatic element adapted to move upon temperature change, a bell-crank movement amplifying lever pivotally mounted adjacent the thermostatic element and given pivotal movement thereby, a snap action, over-center element of spring material arranged to be moved over dead center by the bell-crank lever in a predetermined pivotal movement thereof, and a resilient pressure applying member arranged to store energy therein during the movement of the thermostatic element, said member cooperating with. the lever element and snap'action element and engaging one of the latter elements so that when the resilient member exerts sufficient force the snap action element will be moved abruptly over center and cause the abrupt operation of a device to be operated according to temperature change.

9. In a device of the character described, the combination with a thermostatic element adapted to move upon temperature change, and a device to be operated according to temperature change, a resilient, movement am plifying lever system between thethermostatic element and said device to amplify the movement of said element and operate said device, said system including a substantially non-resilient lever member, and a resilient push member, one of said members being actuated by the thermostatic element to actuate the other member which in turn is urnewest ranged to operate the aforesaid device, and a sna action over-center element of spring material for producing abrupt movement of the device, the said element being so arranged with respect to one of the members of the lever system to be moved over center when the resilient push member has stored sufficient energy therein by reason of a predetermined movement of the thermostatic element.

10. In a device of the character described, the combination with a thermostatic element adapted to move upon temperature change, a bell-crank movement amplifying lever pivotally mounted adjacent the thermostatic element and given pivotal movement thereby, a snap-action, over-center element of spring material arranged to be moved over dead. center by the bell-crank lever in a predetermined pivotal movement thereof and a resilient pressure applying member engaging the lever element and arranged to store energy therein during the movement of the thermo static element, said member being disposed with reference to the lever element and snap action element so as to force the snap-action element abruptly over center when suflicient force has been accumulated in the resilient member, one of the last mentioned elements being arranged to operate a device to be operated according to temperature chan e.

SNEY P. VAU

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