US1974646A - Thermostatically operative valve - Google Patents

Description

Sept. 25, 1934.

FIG 1.

R. J. DOUGHERTY THERMOSTATICALLY OPERATIVE VALVE 'Filed Sept. 8. 1932 Patented Sept. 25, 1934 1,974,646 THEBMOSTATICALLY oraaa'nva VALVE Robert J. Dougherty, Ambler, Pa, asalgnor to John Wood Manufacturing Company, Inc.,

Conshohocken, Pa., a

corporation of Delaware Application September 8, 1932, Serial No. 632,103

10 Claims.

My invention is applicable to control the flow of gas to a burner which is part of a water heater, by location of the thermostatic element in the body of water which is being heated. That thermostatic couple comprises a tube of copper,

or other metal having a high coeflicient of expansion, and containing a rod of another material having a coeflicient of expansion which is substantially zero throughout the range of temperatures to which the couple is subjected. My invention includes means, accessible from the exterior of the valve casing, for adjustably varying the effective length of such inner member of said couple, and means interposed between said themiostatic couple and the valve, adapted to multiply the relative movement of said couple and effect snap action of the valve.

In the form of my invention hereinafter described; said tubular member of the thermostatic couple is carried by a cast metal casing which may be permanently rigidly supported by the wall of a water container, and the other member of the thermostatic couple is axially adjustable in said tubular member at the end of the latter projecting into the' water container; so that the temperature at which snap action of the valve is effected may be varied by rotation of the irmer member of the couple to shift its axial position with reference to the outer member of the couple.

My copending application Serial No. 602,235 relates to valves of the general character above defined but, in that case, the tubular member of the thermostatic couple is a unitary part of the cast metal casing which may be permanently rigidly connected with the wall of the water container, which casting entirely incloses the other member of the thermostatic couple. The embodiment of my present invention chosen for illustration is less costly to manufacture in that 40 the cast metal casing is designed to terminate at the inner wall of the water container and the tubular thermostatic element is formed of wrought metal in screw threaded engagement with that casting at its outer end and in screw threaded engagement with the inner member of the thermostatic couple at its inner end with respect to said container. The latter construction and arrangement facilitates the initial calibration of the device for given temperatures at which it will operate the valve. Moreover, in my previous application aforesaid, I have shown a resilient snap acting member which is symmetrical with respect to the line of pressure by which it is operated and which line is normal to the plane of said snap element, whereas, I have found that by stressing the snap element obliquely to the line of force by which its snap action is effected, the distortion of said element which must precede the reversal of direction of its'convexity is facilitated and, consequently, the differential of temperature bet-weenthat at which said element is snapped to open the valve and the temperature at which it is snapped to close the valve may be very materially reduced. For instance, such temperature diflferential of the structure shown in my copending application aforesaid may be as much as 20 F., whereas, by the construction and arrangement herein disclosed, I have been able to reduce such differential to approximately 10 F. That improvement is of great commercial importance in that it enables the manufacturer to guarantee the maintenance of a continuous supply of hot water with a minimum variation in temperature thereof. Moreover, in the form shown in said copending application, the axial adjustment of the inner member of the thermostatic couple is limited to effect merely changes in the degree of temperature of the water being heated without rendering the thermostatic couple inoperative with respect to the valve. However, I have found that it is advantageous to so construct and arrange the means for effecting relative adjustment of the members of the thermostatic couple that such adjusting means may be used to render the thermostatic couple inoperative and thereby permit the valve to be closed and held shut by its spring, at the will of the operator, without the necessity of employing any auxiliary valve with which to shut off the supply of gas as is necessary in the form of my invention shown in said copending application.

My invention includes the various novel features of construction and arrangement hereinafter more definitely specified.

In said drawing; Fig. I is a plan view of a thermostatic valve casing in engagement with a water container, a fragment of which is shown in section.

Fig. II is a fragmentary longitudinal diametrical sectional view of said casing and its appurtenances, taken on a horizontal plane.

Fig. III is an inner face view of the snap action unit which includes two resilient members and a rigid frame holding them in predetermined relation independently of the casing in which said unit is shown assembled in Fig. II.

Fig. IV is an enlarged fragmentary diametrical sectional view of the thrust disk shown in similar section in Fig. II, showing the toric curvature of the edge thereof which contacts with the snap elements.

In said figures; .the valve casing 1 is conveniently formed of cast metal with the gas inlet 2 and the outlet 3 upon opposite sides of the partition 4. Said partition 4 has valve ports 5 through it controlled by the valve 6 having the inner stem 7 mounted to reciprocate in the bearing 8 in said partition. Said valve is continually pressed toward its seat by the spring 10 which bears at its inner end upon said valve 6 encircling the outer valve stem 11. Said spring abuts at its outer end against the closure cap 12 which is detachably engaged with said casing 1 by two screws 14. Said valve stem 7 carries the screw 15 at its inner end in axial adjustment therewith and both said screw and the outer valve stem 11 are slotted to facilitate axial adjustment of said screw in cooperative relation with the tripod spring 16 by which said valve is snapped open in opposition to the pressure of said spring 10, as hereinafter described.

Said valve casing 1 is rigidly but detachably connected with the thermostat casing 18, conveniently by the screws 19. Said casing 18 has the screw thread 20, conveniently of a tapered standard pipe size, for engagement thereof with the water container comprising the cylindrical shell 21. Engagement of said casing 18 with said shell 21 is conveniently eifected by means of the hexagonal wrench hold 23 on said casing 18. Said casing 13 terminates at the inner wall of said water container 21 but carries the tubular thermostatic member 24 which is conveniently a cut length of copper pipe having the screw thread 25 at its outer end rigidly connecting it with said casing 18 by which it is supported. Said tubular thermostatic member 24 has, at its inner end with respect to said container 21, an internal screw thread engaging the external screw thread 26 on the cup-shaped bushing 27, which is axially adjustable in said thermostatic tube 24, conveniently by means of the screw driver slot 28 at its inner end. Said bushing 27 also has the internal screw thread 29, of a pitch different from the thread 26, for engagement with the screw thread 30 on the cylindrical rod 31, which is the other member of the thermostatic couple. Said rod is preferably formed of an alloy of ferric metal of such composition that it remains of substantially invariable length throughout the range of temperatures to which said couple is subjected.

The arrangement above described is such that said thermostatic rod 31 may not, only be axially adjusted by turning it, but its initial axial position may be precisely and variably determined by rotation of said bushing 27 to effect relative axial movement of said tube 24 and rod 31, without turning the latter, and, when the desired position is attained, said bushing may be sealed in its adjusted position by any suitable material, for instance, solder or other fusible metal 32 which also seals the inner end of said thermostatic tube 24 against ingress of the water 33 in said container 21; variations in the temperature of which effect relative movement of said thermostatic couple and operation of said valve 6, as hereinafter described.

It may be observed that the above described construction and arrangement of the means for initially adjusting and calibrating the members 24 and 31 of the thermostatic couple are essentially difierent from the calibrating means shown in my copending application aforesaid in that, in this case, axial movement of the rod member of the thermostatic couple may be effected without turning the rod, by rotation of the bushing 27, and the necessary calibration thus facilitated, so that it may be effected with less expenditure of time and labor than in the prior form of my invention aforesaid. Moreover, the construction shown in Fig. I is advantageous in that when the calibration has been effected, the means for effecting it are sealed against possible tampering by anyone who handles the valve structures in comn exgce. I

The oute end of said thermostatic rod 31 bears against the thrust disk 35, as shown in Fig. II. As best shown in Fig. IV, said disk 35 has the annular torically curved edge 36 for bearing against each of the three limbs of said tripod spring 16 and permitting greater freedom of rel ative movement thereof than is possible with the knife edge bearing of the thrust disk shown in my copending application aforesaid. Said spring is made of concavo-convex form with its concave surface normally presented toward said thrust disk 35, and of such configuration as to normally permit the valve 6 to be seated upon said partition 4 by the spring 10, to prevent the passage of gas from said inlet 2 to said outlet 3.

As shown in Fig. III, each of the three limbs of said tripod spring 16 is tightly held in the annular frame 38 by respective screws 39. Moreover, radial movement of each of the three limbs of said spring 16 is prevented by contact with the abutment flange 40 on said frame 38, as indicated in Figs. II and III.

Said annular frame 38 also carries the single auxiliary spring 41 interposed between two of the limbs of said spring 16, as shown in Fig. III, and tightly held at its outer end by the screw 42 engaging said frame, with the outer end of said spring 41 tightly fitted against said abutment flange 40 on said frame 38.

The inner end of said spring 41 is bent toward the spring 16, as shown in Fig. II and indicated by the smaller dotted circle shown in Fig. III, and applies the entire stress of said spring 41 upon said spring 16 in unsymmetrical relation to the latter so as to continually tend to distort it from its normal concavo convex curvature by tilting the central portion of said spring 16 ob liquely with respect to the common axis of said spring 16, valve 6, and thermostatic rod 31; whereas, the force exerted by the thermostatic couple 24, 31, is symmetrically applied to said spring 16 by the pressure of the annular flange of the thrust disk 35 upon the three limbs of said spring 16 at equal radial distances from the center of said spring 16.

The function and effect of said auxiliary spring 41, thus disposed in unsymmetrical relation with respect to the figure of the spring 16, is to stress the latter obliquely with respect to the axis of the thermostatic rod 31 which, of course, coincides with the direction of application of the force of relative movement of the members of said thermostatic couple to effect snap action of said spring. Such oblique stress facilitates the distortion of said spring 16 which is necessary to permit reversal of its convexity, in view of the fact that its outer ends are held by the screws 39 and the abutment flange 40 against radial movement.

In other words; it is necessary for the central portion of said spring 16 to buckle in order to effect the reversal of its curvature from being concaved toward the valve 6 to being convexed toward the valve 6 in order to open the latter under stress of the thermostatic couple against the stress of the spring 10, and such buckling movement is facilitated by the aforesaid oblique stress of said spring 41 upon said spring 16.

Fig. II shows the parts of the structure above described in the position in which the water is at the temperature for which the thermostatic couple has been calibrated and, consequently, the 'valve 6 is permitted to be shut by its spring 10 seat by contact of said spring 16 with the adjusting screw 15. In that position, said spring 16 is reinforced by the inner end of said spring 41 and obliquely stressed with respect to the line of force by which its curvature is reversed and, consequently, the distortion essential to such reversal is facilitated, to restore the spring 16 to its normal curvature shown in Fig. II. It may be observed that the arrangement described is such that although opening movement of said valve 6, to the right in Fig. II, is effected solely by the snap action of said tripod spring 16, induced by the pressure upon it. in the direction of the axis of the rod 24; reverse movement of said spring to restore it to its normal form convex to the left in Fig. II, is assisted by said auxiliary spring 41. In fact, such reverse movement is initiated by said spring 41 when pressure upon said spring 16 to the right in Fig. II is relaxed and relieved by expansion'of the tubular member 24 of the thermostatic couple under increment of temperature absorbed from the heated water 33.

As shown in Fig. II; said annular spring frame 38 is conveniently fitted in the valve casing 1 in contact with the inner surface of the flange 43 of the latter, and I find it convenient to make said casing 1 of a die casting with respective recesses 44 molded therein to receive the outer ends of the screws 39 and 42 by which said springs 16 and 41 are held in their annular frame 38, to thus insure the precise location of said frame 38 in said casing 1. Moreover, I flnd it advantageous to provide the casing 18 with the peripheral annular flange 45 to overhang the perimeter of the flange 46 on the casing 1 to insure the fitting together of the casings 1 and 18 in proper coaxial relation, regardless of any inaccuracy of location of said screws 19.

Said thermostatic rod 31 is axially adjusted in the described screw threaded connection with the thermostatic tube 24 so that the spring 16 is continually under stress which is nearly sufiicient to cause it to snap to the right to open the valve 6; in order to minimize the relative movement of the members 24 and 31 of the thermostatic couple required to effect such snap action of said spring 16. The extent to which said valve 6 is thus opened may be varied by axial adjustment of said screw 15. The precise temperature at which the snap action is effected may be varied, as above contemplated, by turning movement of said thermostatic rod 31, and such movement is conveniently effected by means of the collar 48 which is detachably hut rigidly connected with said rod 31 by the set screw 49, indicated in dotted lines in Fig. II, which extends through the sectoral slot 50 in the side of said casing 18 opposite to the sectoral slot 51 shown in Fig. I, through which the index pointer and handle 52, which is in screw threaded engagement with said collar 48, projects in cooperative relation with the arcuate series of graduations 54 on the outer surface of said casing 18, as shown in Fig. I.

As shown in Fig. I; said handle 52 is turned to the hot" side of said graduations 54, with the effect of opening said valve 6 and keeping it open until the water 33 has reached the greatest degree of heat within the range of the apparatus shown; whereupon, the expansion of the tubular thermostatic member 24 permits the valve 6 to assume its closed position shown in Fig. 11.

In other words, movement of saidhandle 52 to the position shown in full lines in Fig. I, and also indicated in dotted lines in Fig. II, unscrews the thermostatic rod 31 to the right to the greatest axial extent limited by the arcuate extent of said sectoral slot 51. On the contrary, movement of said handle 52 upwardly with reference to Fig. I, toward the opposite end of said slot 51, to the oif" side of said graduations 54, moves said rod 31 axially toward the left with respect to the thermostatic tube 24 to shorten the effective length thereof and permit the valve 6 to be shut by its spring 10 when the water is cooler, in accordance with the position of said handle 52 with reference to said graduations and, as above noted, I flnd it convenient to so calibrate the parts that when said handle 52 is turned to the "01? position, said rod 31 is axially shifted so far to the left in Fig. I as to be rendered inoperative upon the valve which, therefore, remains shut until the operator elects to re-turn the handle 52 to re- 110 establish operative connection between said thermostat and the valve. I find it convenient to make the range of adjustment of the handle 52 such that the temperature of the water 33 may be varied from 140 to 170 F.

However, I do not desire to limit myself to the precise details of construction and arrangement herein set forth, as it is obvious that various modiflcations may be made therein without departing from the essential features of my invention, as 120 defined in the appended claims.

I claim:

1. In a thermostatically operative valve structure; the combination with a valve casing having a fluid inlet port and a fluid outlet port; of a 25 valve mounted to reciprocate in said casing, for controlling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve in one direction; a thermostatic couple adapted to coop- 3 erate to move said valve in a direction opposite to that of the stress of its spring;.a snap spring interposed between said valve and thermostatic couple; means interposed between said thermostatic couple and said snap spring for operating said snap spring and valve by relative movement of said couple; and means for continually imposing stress upon said snap spring oblique to the direction of application of stress from said thermostatic couple upon said snap springs; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

2. In a thermostatically operative valve structure; the combination with a valve casing having a fluid inlet port and a fluid outlet port; of a 145 valve mounted to reciprocate in said casing, for controlling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve in one direction; a thermostatic couple adapted to cooplag erate to move said valve in a direction opposite to that of the stress of its spring; said couple including a tubular member rigidly connected at one end with the valve casing and a thermostatic rod member in said tubular member having one end connected therewith and the other end opposed to said valve; a snap spring interposed between said valve and thermostatic couple; means interposed between said thermostatic couple and said snap spring for operating said snap spring and valve by relative movement of said couple; and means for continually imposing stress upon said snap spring oblique to the direction of application of stress-from said thermostatic couple upon said snap spring; whereby the distortion of said snap spring. preliminary to its snap action, is facilitated.

3. In a thermostatically operative valve structure; the combination with a valve casing having a fluid inlet port and a fluid outlet port; of a valve mounted to reciprocate in said casing, for controlling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve in one direction; a thermostatic couple adapted to cooperate to move said valve in a direction opposite to that of the stress of its spring; said couple including a tubular member rigidly connected at one end with the valve casing and a. thermostatic rod member in said tubular member having one end connected therewith and the other end opposed to said valve; a snap spring interposed between said valve and thermostatic couple; said snap spring being initially bent away from said valve at the axis of the latter, but capable of flexure in the opposite direction; means interposed between said thermostatic couple and said snap spring for operating said snap spring and valve by relative movement of said couple; and means for continually imposing stress upon said snap spring oblique to the direction of application of stress from said thermostatic couple upon said snap spring; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

4. In a thermostatically operative valve structure; the combination with a valve casing having a fluid inlet port and a fluid outlet port; of a valve mounted to reciprocate in said casing, for controlling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve in one direction; a thermostatic couple adapted to cooperate to move said valve in a direction opposite to that of the stress of its spring; said couple including a tubular member rigidly connected at one end with the valve casing, and a rod member having one end connected with said tubular member and the other end operatively related to said valve; a snap spring interposed between said valve and thermostatic couple; said snap spring being normally bent away from said valve at the axis of the latter, but capable of snap flexure in the opposite direction, when stressed; means interposed between said thermostatic couple and said valve for transmitting stress to snap said spring and thereby operate said valve by relative movement of said couple; and means for continually imposing stress upon said snap spring oblique to the direction of stress from said thermostatic couple upon said snap spring; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

5. In a thermostatically operative valve structure; the combination with a valve casing having a fluid inlet port and a fluid] outlet port; of a valve mounted to reciprocate in said casing, for controlling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve to close it; a thermostatic couple for opening said valve against the stress of its spring; a snap spring interposed between said valve and thermostatic couple; means interposed between said thermostatic couple and said valve for operating said snap spring and valve by relative movement of said couple; and resilient means for imposing stress upon said snap spring oblique to the direction of application of stress from said thermostatic couple upon said snap spring; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

6. In a thermostatically operative valve structure; the combination with a valve casing having a fluid inlet port and a fluid outlet port; of a valve mounted to reciprocate in said casing, for controlling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve to close it; a thermostatic couple for opening said valve against the stress of its spring; a snap spring interposed between said valve and thermostatic couple; means for preventing movement of the perimeter of said snap spring, including a frame distinct from said casing; means interposed between said thermostatic couple and said valve for operating said snap spring and valve by relative movement of said couple; and resilient means for imposing stress upon said snap spring oblique to the direction of application of stress from said thermostatic couple upon said snap spring; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

'7. In a thermostatically operative valve structure; the combination with a valve casing comprising two separable parts, one part having an annular flange for centering the two parts in coaxial relation; a fluid inlet port and a fluid outlet port, in one of said casing parts; of a valve mounted to reciprocate in said casing, for con trolling the passage of fluid from said inlet port to said outlet port; a valve spring in said casing continually stressing said valve in one direction; a thermostatic couple adapted to cooperate to move said valve in a direction opposite to that of the stress of its spring, including a rodheld in coaxial relation with said valve by the cooperation of the two parts of said casing; a snap spring interposed between said valve and thermostatic couple; means interposed between said thermostatic couple and said valve for operating said snap spring and valve by relative axial movement of said couple, and axial stress upon said snap spring and valve; and means for imposing stress upon said snap spring oblique to the axial line of application of stress from said thermostatic couple upon said snap spring; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

8. A structure as in claim 6, wherein the snap spring has a plurality of arms in symmetrical relation with the axis of the valve, and the frame for said spring has flange means against which the outer ends of said arms abut for preventing their radial movement.

9. A structure as in claim 6, wherein the snap spring has a plurality of arms in symmetrical relation with the axis of the valve, and the frame for said spring has flange means against which the outer ends of said arms abut for preventing preventing movement of the perimeter of said spring; means securing said spring in said frame, independently of other parts of the structure; whereby distortion of said snap spring is limited to the central area thereof; and a spring in said frame imposing stress upon said snap spring oblique to the axis of said spring and frame; whereby the distortion of said snap spring, preliminary to its snap action, is facilitated.

ROBERT J. DOUGHERTY.

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