US2716015A - Snap acting thermostatic valve - Google Patents

Description

Aug. 23, 1955 GW ALLEN 2,716,015

SNAP ACTING THERMOSTATIC VALVE Filed July 18, 1952 E; @0 g j I l 65 T; @.44 6X 5g 20 52 [6 15.0 g 3i N .98 /08 N t //2 J/o 56 Q0 v 1 A 7@ HLTER I 6 73 j 9@ j] y! Y I 30 I Z /fg/ sE'Ix/ivr 32/ 4 yz ,l i*

I i IMI /Qeowge /l/ United States Patent Olihce 2,716,0l Patented Aug. 23, 1955 SNAP ACTING Hmrnnosrnrc vALvE George W. Allen, Indimapolis, lud., assigner to Stewart- Warner Corporation, Indianapolis, Ind., a corporation of Virginia Application July 1S, 1952, Serial No. 299,565

3 Claims. (Cl. 251-66) This invention has as its principal object to provide a novel snap acting thermostatic valve which is positive in its operation and which may be manufactured at relatively low cost.

Yet another object is to provide an improved valve of this character which is proof against leakage, either from the valve to the outside or through the valve when it is in closed position.

Other objects and advantages will become apparent from the following description of a preferred embodiment of my invention which is illustrated in the accompanying drawing.

In the drawing, the single gure shows a vertical medial sectional View through a snap acting valve embodying the present invention with typical equipment of one type ordinarily used therewith shown diagrammatically.

In the operation of heating equipment, particularly heaters supplied with liquid fuel, there is among other things the advisability of providing a valve for interrupting the flow of fuel to the nozzle or other fuel consuming device if the heater or some other portion of the heating equipment becomes too hot. Preferably the valve closing action should be abrupt rather than gradual because a certain minimum rate of of fuel tlow is required in order to insure combustion and thus fuel owing in less quantity will accumulate inasmuch as it is not consumed by the combustion process. Snap action is practically a necessity for control of a heater of the spray nozzle type, since otherwise the nozzle will become choked with carbon when the pressure drops below that essential for good atomization. Preferably, also, once the valve has closed it should remain closed until manually reset if it is to be used as a safety shutolf valve.

The drawing shows the valve of the present invention in such a typical application. Fuel from any suitable source is brought through a tube l) to a pump l2 and from the pump through any customary shutoff valve 14 to a filter 16 which is for the purpose of removing solid particles from the fuel, and thence by way of the tube i8 to the valve 29 which forms the subject matter of the present invention. From the valve the fuel passes by way of a tube 22 to a burner nozzle 24. The purpose of the valve 20, therefore, is to stop the flow of fuel to the nozzle 24 automatically under certain conditions to be explained below The valve is intended to be operated by a conventional thermostatic bulb 26 which supplies fluid under pressure through a tube 23 to a litting 36 connected to a chamber forming member 32 of the valve 20. The situation, therefore, is that whenever the bulb 26 has its temperature increased it will raise the pressure in the tube 28 and cause liquid to flow into the chamber 32. Conversely, lowering the temperature of the bulb 26 causes liquid to flow from the chamber 32.

The valve 26 is comprised of a body casting 34 having a generally cylindrical chamber 36 extending thereinto from the bottom. At a point well Within the casting the chamber 36 communicates through an axial opening 38 with a valve chamber 40 which is cored or drilled so as to have an inlet passage 42 communicating with a valve inlet fitting 44. This inlet passage 42 surrounds a downwardly facing valve seat 46 through the center of which there is an opening 48 communicating with an outlet cored passage 50 which leads in turn to an outlet tting 52. There is also a drilled opening 54' leading through the top portion of the casting and concentric with the valve seat 46.

A poppet valve stem 56 extends through the passages from top to bottom of the device, with its upper end bearing against a socket forming member 58 carried inside and at the end of a corrugated bellows 60. The

lower end of this bellows is soldered or brazed to a ring 62 which lies against the upper face of a gasket 64 seating in turn against a machined face on the casting 20. A ilanged, deeply drawn cup shaped cap 66 loosely encloses the bellows and has its ange in face to face contact with the top face of the ring 62, the cap,`ring, gasket and casting being secured tightly together in the relative positions indicated by means of screws 68.

rhe upper end of the cap 66 is provided with a bushing 70 which carries a headed stem or button 72 loosely fitted therein such that the outer end of the stem 72 is above the end of the cap 66, Whereas the lower end rests against the outer end of the bellows 6l) in alignment with the valve stem 56. The button 72, therefore, is available to an operator for pushing the stem 56 downwardly, while the bellows 6i) prevents the possibility of leakage to the outside which might occur if ordinary packing were depended upon to provide sealing around the axially movable stem S6.

At the lower end of the device there is the drawn sheet metal cup 32 previously referred to which is sealed against the lower face of the casting 20 by a gasket 74, this assembly being accomplished by passing screws 76 through an outwardly turned flange of the cup 32 so that these screws pass through the flange and through the gasket 74 and are threaded into the casting 20. The

`cup member 32 at its upper end carries an inwardly extending tlange or ring 7S which around the opening at its center is soldered or otherwise suitably secured to the upper end of a corrugated bellows member 80. The lower end of this bellows is closed by a at end 82 and the space within the cup 32 and surrounding the bellows S0 is lled with the iluid which also is present in the bulb 26. Thus, the bulb 26, the tube 28, and the space within the cup 32 surrounding the bellows 82 constitute together a sealed hydraulic system with the result that heating of the bulb 26 causes the lower end 82 of the bellows member S0 to move upwardly slightly.

Within the bellows 86 there is a tubular member 84 having its lower end closed as at 86, this closed end being provided with a button 83 which bears against the inner surface of the at end 82 of the bellows b. Within the tubular member 84 there is a comparatively stiff coil spring which rests against the inner surface of the tube end 86 at one end while its upper end supports an enlarged head 92 formed at the lower end of the valve stem 56. Above this head 92 there is a second and much lighter spring 94 which extends between the head 92 and a collar 96 threaded into the upper opening ot' the tubular member 84. The tubular member 84 therefore floats relative to the head 92 of the valve stem S6 between the springs 90 and 94.

102 between the two.

discs,.p1us.the length. of the sleeve 162 equals thev depth of the cavity 36 and therefore the discs are maintained in position with a space therebetween by the same rubber gasket" 74 which sealsthe cup'y member 32 tothe valve Ay resilient valve disc 104, formedI of rubber or similar material, is positioned a proper distance below the valve seat 46- andi is secured: to the valve stem 56 by being placedbetweena washer and pin or split ring 166 secured.. tothek valve stem: in a position. directly thereabove anda headed tubular member 108i which surrounds the valve stemf56 withy its head against the lower surface of the resilient ring 104; This tubular member 198. extends into= the cavity formed between the iron. rings 98'andz100 wherel its lower end restsV against a magnetic ring or. bar 110. Preferably'this magnetic member is made of Alnico or' a` similar material. This magnetic disc or bar 110 is somewhatsmaller in diameter orlength than the internaly diameter of the spacing ring 162 and basan opening through its center fitted to the valve stem 56. The lower surface of the magnet rests against the end. of a tubular spacer 1.12, the opposite end" of which passes through the Vcenter of the Ylightrcoil spring 94 and bears againstk the back Y surface of the valve stem head1 921 K f The lengths of the tubular spacing members 112 and 108 are such that when the valve disc 104 isV spaced from the valve yseat 46-an appropriate distance so that the valve is-ope'n,V the magnet 110 rests against the top surface of the iron disc 100y and adheres thereto because of the fmagneti'cV attraction between these members. The valve therefore, is positively held `open bythe force of this magnetic attraction.

As the pressure in the bulb 26 rises with an increase in temperature, this increases the pressure within the cham- Y Vber between the cup 32 and the bellows 80, thereby compressing theV bellows80 so as to shorten the length of ,the stiff spring 90. Eventually this spring is shortened lsutiiciently vso thatit develops a force just suliicient to 'push the magnet 1-10 away from the iron ring 100. Inas- Y much as the force exerted by a spring is a direct function of the amount of its compression, whereas magnetic attraction is a function of the square ofthe distance betweenthe members forming the magnetic circuit, it ywill be apparent that as'soon as the magnet 110 is pushed slightly Y away from the iron disc 100 the valve stem' 56 will be ,I thrown upwardly with a snap action.

Y When the resilient valve disc 10,4 is brought against the valve seat 46l so Yas to sealthe valve, the upper surface of the magnet 110 will be just` shortY of contact with the top iron disc 98 Vwith lthe result that both Vthe magnetic attracion` beweenl the members 11G and 98 Vand the pressure of the spring V90 will maintain the valve in tightly closed position.V Even after the pressure in theV bulb 26 subsequently decreases Y because of cooling, the elongation of the bellows S which follows will not cause the valve to open inasmuch as the forces due to lengtheningv of the spring 90 and the simultaneous compression of the lightspring 94 will not be suicient to overcome the magnetic attraction between the members 110 and 98. The valve there-A Vforerremains closed after it has once been actuated.

' from its top position to one in contact with the iron ring Y 1'00 thereby reconditioning the valve for a new cycle of operation.

VVIt should be noted that because of the bellows at each Vend of the valve stem, leakage aroundY the valve stem to the outside is not possible even though the valve, is free to move in an axial direction; ltV should also be noted 1 that the valve acts positively in asnap action mannerV between its open and closed position andl thatY when iny the closed position it does not automatically reopen until an open position so as to exert a magnetic 'force'onsaid' operator has had an opportunity to investigateV the, situation and push downwardly upon the button 72. Further it is evident that when the valve is in the closed position it is positively held tightly against its seat bythe magnetic attraction between the members 110 and 98.

It is desired that the valve` be of the automatically Y resetting, snap acting type, the button 72 can be climiv nated and the spring 94 strengthened, so that upon elongation of the bellows a pointj will be reached where the compressed spring 94.w1ll pull theV magnet 110away from the disc 9S and snap it into engagement with the lower disc 16D, thereby opening the Valve.

Having described my invention, what YI claimasV new and useful and desire'to secure by Letters atent of the United States is:

1. ln a snap acting valve, a valve body having inlet and outlet passages formed therein with a valve seat providing communication between.- said passages, a valve member movable toward and away from said seat to close andopen said valve, a valve stemy carrying said valve member and mounted for axial movement, resilient means for biasing'said valve stem for axialV movement in. one direction or the other, depending upon the'positionof said re. silient means, an actuator vfor positioningv saidl resilient meansto determine the direction and amount'of bias, said actuator including Ya corrugated metal bellows enclosing said resilient means and one end of said valve stem and saidV bellows acting to center said'resilient means and said one end of said valve stem, a magnetic member carried;` by and movable with said valve stem, av member of magnetic permeability positioned to be in contact'with said; magnetic member when said valve is-in open position andto exert Ya magnetic force on said valve stem to hold said valve stem in open position, a second `member of magnetic permeability so positioned as to be immediately ad-V jacent said magnetic member when saidy valve is in closed:Y

positionV and to exert a magnetic force on said valve stem to hold said valve stem in closed position, means including a second corrugated metal bellows for enclosingl the other end of said valve stem andfor centering said other end of said valve stem, and means available to anroperator exteriorly of the last said bellows for moving the end of the last said corugated metal bellows so as to push said valve stem from one end of its stroke to the opposite end= thereof.

2. In a snap acting valve, a valve body having inlet andoutlet passages formed therein with a valve seat providingl communication between said passages, a valve member movable toward and away from said seat to close andopen said valve, a valve stemV carrying said 'valve member and mounted for axial movement, resilient means for biasing said valve stem for axial movement in one direction or the other, Vdepending upon the position of said resilient means, said resilient means floatingfreely with'saidl valve stem, an actuator for positioning said resilient means to determine the direction and amount of bias,

means for moving saidV actuatorV in opposite directions, av Y Y' magnetic member carried by and movable with said valveY stem, a second magnetic member having an attraction for the first magnetic member and positioned to be in contact with said iirst magnetic'member when said valve is in valve stem to hold said valve stem in open position, and' a third magnetic member adapted to have an attraction for said iirst magnetic member and so p'ositioned'as to be immediately adjacent said rst magnetic member when said valve is in closed position.

3. In a snap acting valve, a valve body having inlet and outlet passages formed therein with a valve seat pro,- viding communication between said passages, a valve.

member movable toward and away from said scatto-V paratively .strong resilient means for biasing said valve,Y

stem for axial movement in a direction to close said valve, comparatively Weak resilient means for biasing said valve stem in an opposite direction so as to maintain said valve stem under the influence of said strong resilient means, an actuator for moving both said resilient means together, a magnetic member carried by and movable 5 with said valve stem, a member of magnetic permeability positioned to be in contact with said magnetic member when said valve is in open position and to exert a magnetic force on said valve stem to hold said valve stem in open position against the influence of both said resilient l0 means until both said resilient means have been moved together to a predetermined compressed position, and a second member of magnetic permeability so positioned as to be immediately adjacent said magnetic member when said valve is in closed position, said second member of 1 magnetic permeability exerting a magnetic force on said 6 valve stem suflicient to overcome the force developed by said weak resilient member when said weak resilient member is compressed, and manual means for moving said valve stem in a direction for opening said valve.

References Cited in the file of this patent UNITED STATES PATENTS

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