US1988956A - Snap action valve mechanisms - Google Patents

Description

Jan. 22, 1935. R. E. NEWELL SNAP ACTION VALVE MECHANISMS Filed July 26, 1930 Patented 1935 UNITED sr rE s PATENT OFFICE.

The present invention relates broadly to the art of fluid distribution, and more particularly to an improved valve of the so-called snap action type, especially useful for the control of gas. or

fluid burners.

Developments in the art, and more particularly with respect to gas and fluid burners, have been such as to make it desirable to utilize snap action valves for controlling the fuel supply thereto. The present. invention has for one of its objects the provision of an improved valve structure possessing desirable characteristics with respect to a snap opening or closing, and suitable for use in systems wherein either a temperature or pressure variation is available for controlling purposes.

In the accompanying drawing I have shown for purposes of illustration only, certain preferred embodiments of the present invention.

In the drawing, Figure 1 is a longitudinal sectional view through one form of thermostatic valve constructed in accordance with the present invention;

Figure 2 is a top plan view, partly broken away,

of a valve of the type illustrated in Figure 1;

Figure 3 is a detail sectional view, on an enlarged scale, of the valve disk;

Figure 4 is a detail sectional view, on an enlarged scale, of the adjustable stop screw; and

Figure 5 is a view partly in elevation, partly in section and partly broken away, illustrating an-' other embodiment of the invention.

It has heretofore been proposed to provide valves of the snap action type in which th snap action has been obtained by means of a disk of spring metal adapted to be flexed from one position of concavity into another position, the movement being relied upon to obtain the desired operation of the part being controlled. Such structures, while responsive to the conditions which it is desired to control, are open to certain objections, depending upon their particular constructional characteristics. In some cases the operating disk is perforated at its center portion whereby the disk is correspondingly weakened and its sensitiveness is impaired. In most cases the disk has been held against movement at one portion thereof, whereby a uniform flexing action has not been obtainable. Also in most cases with whichI am familiar it has been considered desirable to so construct the disk that it will have a difierent amount of movement in one direction than in the other to thereby give it the required sensitiveness of operation, and to utilize a lost motion connection between the disk and the second for the reason that the lost motion connection has required installation of the valve in a predetermined manner such that the pressure of the gas or other fluid beingcontrolled will not be effective for opening the valve to the extent permitted by the lost motion present in the valve structure.

In accordance with the present invention there is provided a construction in which the disadvantages and objections before referred to are obviated, and correspondingly improved operating results and characteristics obtained.

As illustrated in Figure 1 of the drawing, there is provided a valve casing 2 having a seat 3 therein adapted to be controlled by a valve disk 4. As is customary in structures of this type, the seat is intermediate the inlet and outlet ports or connections 5 so as to control the flow of fluid through the casing.

Secured within the casing is a tube 6 having a relatively high coeflicient of expansion, the tube containing a rod 7 having either a negligible or relatively low coefficient of expansion. By reason of this construction, it will be apparent that if the tube 6 is subjected to the temperature of the medium which it is desired to control, the

, tube will tend to contract as the medium cools in temperature, and thereby move the rod 7 upwardly as indicated in Figure 1 oi the drawing. This upward movement will in turn be transmitted to a lever 8 having an adjustable fulcrum in the form of a temperature adjusting screw 9. The movement of the lever is transmitted to a flexible disk 10 illustrated in Figures 1 and 3 of the drawing as convexed upwardly with the valve disk in seated position.

The flexible disk is carried by the valve disk 4 in such manner as not to interfere with the free flexing of the disk. Desirable results may be obtained by providing the disk with a flange or rib 11 adapted to be turned inwardly over the edge of the flexible disk and thus hold it in position, the upper surface 12 of the valve disk being cut away below the flexible disk so as to permit movement to the extent permitted by the engagement bea tween a shoulder 16 on the push pin and the shoulder formed by the inturned edge 17 on the stop screw. The construction of the parts is conveniently such that the free end of the push pin 15 extends beyond the end of the adjustable stop screw a short distance equal to slightly more than half of the total flexing distance of the disk 10. The outside diameter of the upper end of the stop screw 13 is such as to slide easily within a central opening 18 in the valve disk.

Extending through a cap 19 carried by the valve casing is an adjustable screw 20 carrying a disk 21 at its lower end. This disk, and the screw perature conditions, it will be apparent that the downward pressure of the lever 8 against the convex upper side of the disk 10 will be transmitted to the valve disk 4 and will be in opposition to the spring 14 and the push pin 15. This tends to press the valve disk 4 more tightly into engagement with its seat, this condition continuing and becoming greater and greater until the critical point is reached. At this point the disk 10 will spring to an opposite curvature. This will cause the peripheral edge of the disk to move upwardly, thereby lifting the valve disk 4 away from its seat to the extent permitted by the engagement of pins 23a carried by the valve disk, with the disk 21 on the adjustable screw 20.

The flexible disk having been sprung to an opposite curvature, and having thereby'opened the valve, retains the valve in such opened position until such time as the temperature of the medium being controlled increases to an extent sufflcient to expand the tube 6, thereby releasing the lever 8 from the holding influence of the rod 7 andpermitting the spring 14 through the push pin 15 to push the flexible disk 10 in the opposite direction to an extent sufiicient to cause it to resume its original position. In resuming this.

original position and in snapping to the opposite curvature, the valve disk 4 will again be brought into engagement with its seat. j

It is to be pointed out that the valve structure just described is characterized by the fact that during such period of time as the valve is preparing to open, it is gradually pushed tighter and tighter toward its seat, thereby precluding any possibility of leakage until a critical temperature has been reached. It is also to be noted that the construction of the flexible disk is such that pressures exerted in either direction are evenly spread over its whole area and not -so concentrated in small sections thereof as to tend to over-strain the metal.

The disk is also characterized by a total movement which is the same in opposite directions and which is the same at the center of the disk as at the outside, thereby distinguishing from structures as heretofore used in which either the outer edge is relatively stationary while the center is snapped, or in which'the center is relatively sta-:

tionary while the outer edge is snapped.v -A construction of the character disclosed herein .obtains the advantage of a more perm'anent and de pendable snap action for the reason that the equalized movement of the flexible disk is such that the tension or tendency to snap is equal on both sides. With other types of the character referred to in which most of the'tension is placed on one side of the disk with only a slight tension on the other side, there is not a uniform action in both directions.

The general construction of the valve having beenreferred to, the steps necessary to effect a setting of the parts for actual operation will now be described.

Assume the flexible disk 10 to be so flexed that its center is up as illustrated in Figures 1 and 3, and the concave side downwardly, with the valve disk 4 in positiononthe seat 3.- The adjustable stop screw 121' willbe threaded inwardly until the push pin 15 almost contacts valve disk 10. The

indicator 24 carried by the fulcrum temperature adjusting screw 9 will then be set to cold position, the tube 6 being screwed out of position if necessary so that the lever 8 will drop into place. By then pressing firmly on the long end of the lever 8 the push pin 15 will be-caused to recede into the adjustable stop 13 until the flexible disk 10 rests on the upper end of the stop screw 13 itself. The stop screw will then be threaded outwardly by means of a screw driver until the valve disk 4 is snapped to open position by the flexing action of the flexible disk 10, the reversal of curvature of the flexible disk causing its outside edge to move upward with a corresponding movement of the valve disk.

The thermostat is now ready for calibration, which is accomplished in the following manner. The tube 6 is submerged in water or the like at a temperature, for example, of 123. The indicator 24 is set at ,-7 higher than the water temperature. The outer edges of the valve disk are then pressed downwardly so thatthe valve disk is seated. The tube 6 is then slowly screwed inwardly until its action on the lever 8 causes the valve disk to snap to open position. The thermostat is now calibrated for opening at any temperature 7 lower than the indicator setting.

Assuming that it is desired to have the valve preset at a temperature 7 higher than the indi-- cater setting, so that the indicator wherever it is placed will always be at a point half way between the actual opening and closing temperatures at which the valve will operate, the following procedure is resorted to. The cap 19 is screwed into position, the adjustable back stop screw 20 having been screwed outwardly so as not to permit the disk 21 to engage the pins 23a when the valve disk 4. is in open position. The tube 6 is then inserted in water at a temperature of 137, and the'stop 20 is slowly screwed inwardly until the valve disk is heard to snap to closed position. The thermostat is then ready for service. I

In Figure 5 there is illustrated a construction in which parts corresponding to parts already described are designated by the same reference characters having, however, a prime afiixed thereto.

In this embodiment of the invention, the tube 6 and rod 7 of Figure 1 are replaced by a bellows 25 within a suitable housing 26 which is threaded onto a boss 27 projecting from the valve casing 2'. The periphery of the lower flange 28 of the housing 26 may be calibrated to cooperate with an indiactor or pointer 24' projecting outwardly from the valve casing. I

For cooperation with the seat 3' is a valve disk 4 carrying a flexible disk 10'. The lever B of Fig ure 1 is replaced by a push pin 8 adapted to be actuated by the bellows 25, the action, however, being the reverse of that obtained with the construction of Figure 1 in that when the bellows cools due to a decrease in the temperature of the medium to which it is subjected, it contracts and thereby relieves pressure from the pin 8'.

This release of pressure from the pin 8 permits the push pin 15', under the influence of the spring 14 to move upwardly, thereby exerting pressure against the under side of the center of and consequently temperature ranges. By setting the back stop closer to the valve disk to limit the movement thereof, a smaller capacity will be obtained and a very much smaller temperature range, while by moving it in the oppo-' site direction, the opposite results will be obtained. The outer end of the adjustable back stop may be housed within a suitable cap 29.

With reference to the structure just described, it will be assumed that instead of calibrating it to exact maximum and minimum temperatures, as was disclosed inconnection with the valve of Figures 1 to 4, leavingthe capacity to be what it may, it is desired to set the valve for an exact maximum capacity, leaving the total temperature range to come as it may. Either method may be used on both types of thermostata Under the condition just assumed, the parts will be assembled approximately as illustrated in Figure 5, taking care that the flexible disk 10' is snapped to open position, i. e., with the concave side facing the push pin 15'. The adjustable stop screw 13' 'will be threaded inwardly until the back of the valve disk 4 is about one-sixteenth of an inch from the back stop 12'. The operator will then press down firmly on the pin 8 with one hand, while with the other hand the adjustable stop screw 13' will be backed out slowly until a snap is heard, which means that the back of the valve disk 4' has engaged the adjustable back stop 12 pressing against the outer edge of the flexible disk 10' and that continued pressure on the rod or pin 8' has caused the outer edge of'the flexible disk 10' to spring upwardly and throw the valve disk into closed position.

The downward pressure on the rod 8' is then released, and the back stop 12' gradually screwed inwardly until the valve disk touches its seat. This movement is continued until the valve disk snaps to open position. The thermostat may then be submerged in water at a temperature of 75. for example, and the housing 26 turned to bring pressure on the rod 8' until such time as the valve disk snaps to closed position. The indicator of the thermostat may then be set, for example, at 73. The thermostat is then calibrated to snap to closed position at 2 above the indicator setting. With the indicator in the same position, the thermostat may be placed in water at 71.

. If the bellows is designed to operate the valve with a maximum snap capacity with a 4 temperature range, the valve should snap open again with water at 71. If the snap does not occur, the indicator may be moved carefully until the snap is heard. The pointer of the indicator or the indicator dial may then be loosened and readjusted to one-half of the total variation. In

' this way the indicator pointer is maintained half way between the actual valve opening and closing temperatures.

It will be understood that any further adjustment inwardly of the back stop screw 12' will decrease the capacity of the valve as well as the range in temperature in a manner generally similar to that obtained with the structure of Figure 1. Any limiting of the snap disk movement by adjustment of the back stop screw. also reduces the movement required at the center to reverse its snap action, as the movement at thev center and at the outside periphery of the disk is always equalized, as referred to.

Even though the construction of Figure 5 operates in certain respects on the opposite principle from that illustrated in Figures 1 to 4, the results obtained are the same. In both cases the same advantages as to gradually increasing pressure against the seat under a decreasing temperature are obtained, in that with the form shown in Figure 5 the follow spring 14' will .tend to push the valve disk 4' more tightly into engagement with its seat as the pressure on the rod 8decreases due to contraction of the bellows until such time as a critical temperature has been reached, when the valve disk was snapped to open position. In both cases the valve is operated by a valve disk having a uniform movement at the center and at the periphery and having a uniform tension in opposite directions or on opposite sides.

The construction disclosed in the present application differs further .from so-called snap valves as'heretofore constructed, in that the snap action is produced mechanically in both directions under such conditions that the opening movement and the closing movement are substantially the same. With ordinary snap valves in which a lost motion adjustment is utilized, as hereinbefore referred to, there is not such a uniformity of the opening and closing movements. This is necessarily true for the reason that with such structures the valve disk starts to close gradually, such gradual movement continuing until the gas-back pressure on the outlet side of the valve isless than the gas pressure on the inlet side. When this condition obtains, the preponderance of pressure on the inlet side completely overcomes the tendency of the valve to remain open, and forces it shut with a quick action so that the snap eifect during closing is obtained by gas pressure as distinguished from mechanical means.

Not only does the lost motion type of valve give non-uniform movements of the character referred to, but it is necessarily limited to installation under such conditions that the gas flow is always in the same direction. If it were attempted to pass gas, or any other fluid being controlled, through the valve in the opposite direction, the valve would continuously remain away from its seat to the extent permitted by such lost motion connection. Such a. valve'is further characterized by the fact that due to the necessity of extreme accuracy and finally balancing the parts, the valve is subject to variation caused by vibration.

It is further to be observed that a valve of the character herein disclosed possesses the additiona1 advantage that since the closing force is produced mechanically, as distinguished from fluid pressure, the valve is held more tightly closed with the instant structure than with constructions of the lost motion type.

Both structures of this application constitute an advanceover the art in that there is utilized a valve disk having incorporated therewith as a part thereof a flexing member, the action of which, in combination with other parts, serves to instantly throw the valve completely either to its open or to its closed position with a snap action. In addition to the advantages before set forth, the construction just referred to possesses the advanment in the event of damage by'cracking or losing of its snap by too high local temperature,

is permitted. Also by-reason of a valve disk which is larger than the diameter of the flexing member, a larger gas capacity is rendered available by a smaller movement of the diaphragm.

The adjustable back stop 12 or 12' also possesses the advantage not only of making possible an adjustment for various capacities and temperature, but also the advantage that in the event the flexible disk should in time lose some of has tension so as to be unable to snap the valve disk to full capacity, the back stop may be adjusted in such manner that the valve will snap, but at a smaller capacity. In this manner a snap action may be maintained so long as the flexible disk retains a fraction of its original tension.

Other advantages with respect not only to constructional, but operating characteristics will be apparent to those skilled in the art from the foregoing description taken in connection with the drawing. It will be further understood that while I have illustrated and described certain preferred embodiments of my invention, the utility of the invention is not limited to the structures shown, inasmuch as changes in the construction and operation of the parts may be made without departing either from the spirit of the invention or the scope of my broader claims.

I claim:

1. As an article of manufacture, a valve disk having secured thereto a snap action flexing element, said flexing element being carried by and connected only to the valve disk, and being adapted to be flexed past a plane substantially parallel to the plane of the'valve disk.

2. As an article of manufacture, a valve disk having secured thereto a snap action flexing element, said flexing element being carried by and connected only to the valve disk, said valve disk being constructed to permit a flexing movement of said element in oppozite directions past a plane substantially parallel to the plane of said disk.

3. As an article of manufacture, a relatively large valve disk and a relatively small imperforate disk centrally carried entirely thereby, and mounted so as to permit flexing of the center of said disk to either side of a plane passing through the edges thereof.

4. As an article of manufacture, a relatively large valve disk, and a relatively imperforate small flexible disk centrally carried thereby, said flexible disk being secured to the valve disk at .portion of said element havingapproximately equal movement to that of the central portion and in the opposite direction at the same time.

7. In a valve, a valve disk, a flexible element carried entirely by said disk for operating said disk and adapted to impart a snap action thereto, and means for operating said element to simultaoaaeso neosuly impart an approximately equal move-- ment to the centralportion in one direction and to the outer portion thereof in the opposite direction. 1 W

8.,In -a-.valve, a valve disk, snap means for operating said disk carried entirely by said disk and secured thereto at its outer periphery only, and an adjustable non-yielding back stop cooperating with said disk. 1

9. In a valve, a valve disk, and snap operating means for said disk, said operating means including a flexible element carried entirely by said disk and secured at its outer periphery only to said disk, andv an adjustable stop for the valve disk with a yieldable push pin normally engaging one surface of the snap operating means.

10. In a valve, a valve disk, and snap operating means for said disk, said operating means ineluding an adjustable stop for the valve 'disk with a yieldable push pin normally engaging one surface of the snap operating means, and an adjustable back stop cooperating therewith.

11. In a valve, a valve. disk, snap means for operating said disk carried entirely by said disk and secured thereto at its outer periphery only, and means for adjusting the total permissible opening movement of said disk.

, 12. In a valve, a valve member, and a flexible element mounted on and carried entirely by said member substantially in the plane thereof for operating the same, said element being normally curved in one direction and adapted to snap to a position of reversed curvature.

13. As an article of manufacture, a valve disk having a rib projecting from one side thereof,

and a snap action flexing element having its outer edge portions only engaged by said rib.

14. As an article of manufacture, a valve disk having an opening therethrough, and asnap action flexible'disk overlying said opening and secured to said disk at its edge portions only.

15. In a valve, a valve member having an opening therethrough, a flexible element of the snap action type overlying said opening and secured to the valve member, and mechanical means in engagement with opposite sides of said element at all times for producing a mechanical movement thereof in each direction, one of said means extending through said opening? 16. As an article of manufacture, a substantially circular valve disk having a substantially annular rib projecting from one side thereof, and a substantially circular snap action "flexing element having its outer periphery engaged by said rib.

1'7. As an article of manufacture, a valve disk having secured thereto a snap action flexing disk, said flexing disk being carried'by and connected only to the valve disk.

18. As an article of manufacture, a valve disk having secured thereto a snap action flexing disk, said flexing disk being carried by and connected only to the valve disk, said valve disk being constructed to permit a flexing movement of said flexing disk in opposite directions.

19. As an article-of manufacture, a valve disk having secured thereto a snap action flexing disk, said flexing disk being carried by and connected only to the valve disk, the valve disk and flexing disk forming a unit which is free and unattached to the valve.

ROBERT E. NEWELL.

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