US2156830A - Furnace control mechanism - Google Patents

Description

May 2, 1939. Q s ANDERSEN I 2,156,830

FURNAGE CONTROL MECHANISM INVENTOR CHRISTIAN S. ANDERSEN BY MM YW May 2, 1939A c. s. ANDERSEN 2,156,830-

` l FURNACE CONTROL MECHANISM Filed sept. 1o, i937 2 sheets-sheet 2v INVENTOR CHRISTIAN s. ANDERSEN BY MMWYIW.

ATTORNEYS Patented May 2, 1939 UNITED STATES PATENT ori-lcs Pennsylvania Furnace & Iron Co., Warren, Pa.,

a. corporation of Pennsylvania Application September 10, 1937, Serial No. 163,167

2 Claims.

" *I This invention relates to improvements in furx10 be operated either in response to a steam pressure condition or to a water level condition. I

Another' feature of my invention is the ar rangement of a novel toggle actuated snap action control member l'and automatic means for actuating the control member in response to a boiler condition.

' My invention also includes a novel actuating device for a control member operable in response to a boiler water level condition. novel de- 20 vice also includes a novel arrangement ,of a con trol member operating lever extending from within a iloat `chamber to a point outside the same and novel sealing means for the .opening through which the operati-ng lever passes.

Other features of my `invention will appear from the accompanying drawings and speciiications and the essential feature thereof will be summarized in the claims.

In the drawings,

Fig. 1 isa sectional View through a water leg lof a boiler equipped with my novel control mechanism and taken alo-ng the Aline I I of Fig. 2;

Fig. 2 is an elevational view `of the mechanism ofFig. l taken from the right-hand side thereof;

Figs. 3, 4 and 5 are enlarged detail sections of a portion of the mechanism of Fig. l, showing the v parts in various operated positions; while Fig. 6 is a view similar to- Fig. 5, showing a modified form of the valve actuating plungers.

My invention is applicable to a boiler furnace having ,control mechanism which it is desired to operate automatically in response tosteam pressure yor water level conditions. I have illustrated at It the water leg or float ,chamber of such a 45 boiler wherein it will be understood that chamber III is partially. filled with water, the upper portions being filled with steam at boiler pressure as ,is usual in such cases. For illustrative purposes only I have indicated at II a portion 50 of a furnace control mechanism for operation in response to a steam pressure or water level condition in the moiler. The member illustrated is a diaphragm operated gas Valve which, for instance, might supply gas. to the heat generating 55 burner of the boiler furnace. This valve has a a valve plunger Ib reciprocable to open or close port Ila which is closed or opened in responseto the pressure conditions on opposite sidesof the diaphragm IIb. This diaphragm has a small vent IIc leading into the chamber I2 above the diaphragm. This chamber is vented as at I3 5 and whengas pressure is exerted below the dia-I phragm I Ib and chamber I2 is vented to atmosphere, the diaphragm will hold the port Ila open as indicated in Fig. 1. However, if in response to a boiler condition it is `desired to shut off the fuel to the burner, gas or other Vfluid pressure may be admitted through conduit I4 to chamber l2 to create in that chamber equal or greater pressure than that existing below the diaphragm, with the result that port IIa is closed and the burner ceases to generate heat.

For the control of such a valve I I or other control member having similar control effects, I have provided a valve I5 having a port i501, and

the port Ia whereby gas, for instance, supplied at It may pass to conduit I4 and chamber I2 when valve I5b is in open position. A spring I`| biases the valve toward closed position and plungers I3 and I9 may be automatically actuated, fas will presently appear, by Va boiler condition to open the valve I5b and dump gas pressure into chamber I2. A flexible diaphragm 20 seals the valve against gas leakage to atmosphere.

Means is provided for actuating valve I5 in response to a predetermined steam pressure con' dition in the boiler. In the form shown a metal bellows. 2| subjected to steam pressure inthe water leg is connected with an actuating stem 22 extending upwardly out of the watei` leg casing. This connection is sealed against steam leakage at 23. Lever 24 pivoted on the casing at `25 is in operative engagement at the one end with the pin 22 and at the lother end withrod 26, which extends downwardly and is provided at its lower end with the adjustable abutment 21. A bellcrank operating arm `23 is pivotally mounted on the framework at `Il and has a leg 28a engaging the abutment 21 and an upwardly yextending yoke `Z811 carrying a plunger 3E which engages in a notch 3 Ia of rocker 3| which in turn is pivotally mounted on the frame at 32. The free end ulb of the rocker engages the notched portion Ia of the valve operating plunger I8. The plunger has a downwardly extending pin 30a reciprocably mounted in the yoke 28h and spring pressed upwardly by the spring 33 which is compressed between the shoulder 28e of yoke 28h and the lower side faces of the plunger head 30. In effect the rocker 3| and the plunger 3|] form a snap acting casing Ill.

toggle which in the normal position of the parts lies with the rocker in the position of Fig. 5 but in the actuated position snaps the rocker to the position of Fig. 3, thus opening valve |5.

Means is provided for adjusting the action of the mechanism just described in response to the pressure exerted on the bellows 2|. To this end a yoke 34 on lever 24 is provided with a downwardly extending pin 34a and about the pin is a helical spring 35 compressed between the stop pin 34h and an adjustable cap 36 which has threaded engagement with a portion of the fixed casing. The tendency of increased pressure in bellows 2| is to cause a clockwise movement of lever 24 about the pivot 25. By adjusting the compression of spring 35 by means of the cap 36 this action may be adjusted and modified so as to set the device to act at a predetermined steam pressure.

The operation of the portion of the control mechanism just described will be readily understood. Upon the pressure in bellows 2| reaching a predetermined point, pin 22 moves upwardly, causing clockwise movement of lever 24, downward movement of rod 26 and clockwise movement of the bellcrank member 28. This causes movement toward the right of yoke 28h and moves the toggle 30, 3| toward center position, that is, with plunger 30 in line between pivots 32 and 29. This compresses spring 33, and if the movement of yoke 28h toward the right continues until the plunger 30 passes the center line position, spring 33 is effective to snap the rocker 3| to the position of Fig. 3, moving plungers I8 and 9 inwardly and opening valve I5. This will dump gas pressure on top of diaphragm ||b and shut oil gas supply to the boiler burner.

The means for actuating valve I5 in response to a water level condition comprises a iloat 38 in the chamber Il), this float having a downwardly extending guide part 38a and an upwardly extending pin 38h by which it is connected to the control mechanism. This pin is pivotally connected at 39 with the lever 45 which in turn is mounted on the pivot 4| which is rigid with the casing I0. The lever 40 in reality forms one arm of a bellcrank arrangement, the other arm of which is the upwardly extending member 42 engaging the valve actuating plunger I9.

I provide a novel structure at the point where the lever 40 passes outside of the casing |0. A exible bellows 43 is sealed to the lever 40 at the end 43al and is sealed to the cap 44 at the end of the bellows 43h. The cap 44 is tightly secured to the cover plate 45 which in turn is secured in sealed relationship with the flanged opening 46 through which this mechanism is inserted in the The member 41 is a supporting ring for the lever 40 and connected mechanism. It results from this structure that the lever 40 may have a tilting action about the pivot 4| while remaining sealed to the casing l0 without danger of steam or water leakage. At the same time, variations in temperature or pressure within the casing Il) have no effect on lever 40 because of the fixed pivot 4|. In other words, the temperature and pressure effective on rod 40 and bellows 43 will cause no movement of the arm 42.

The operation of the low water control just described is as follows: Upon the water level in the iloat chamber l0 dropping to a predetermined low point, float 38 will move downwardly, causing a downward movement of lever 4|! and a counterclockwise movement of the arm 42 about the pin 4|. This moves the valve actuating plunger I9 inwardly as shown in Fig. 4, thus opening valve I5 and dumping gas pressure on top of diaphragm IIb, closing off the supply of gas to the boiler burner.

A modification of the valve actuating plungers is shown in Fig. 6, wherein the head |9a of plunger I9 has been omitted and this plunger is given the form shown at 48. In the form shown in Figs. l to 5, when plunger I 8 is actuated to the position shown in Fig. 3 it carries plunger I9 with it. This moves the plunger away from arm 42, which ordinarily is not objectionable but with the plunger formed as is shown at 48 the plunger I8 may be moved independently of the plunger 48.

It will be noted that the valve |5 is actuated either in response to a predetermined steam pressure or in response to a predetermined water level or in response to both conditions.

While I have shown the valve |5a open for the purpose of producing a stated control effect on valve it will be understood that I intend my novel control mechanism for use with any suitable control member wherein the action of a member placed at the position |5 will cause the desired control eiect with respect to the boiler control mechanism. In other words, I have shown mechanism automatically responsive to a variation in steam pressure and water level conditions by which any desired control action may be brought about.

What I claim is:

1. In control mechanism of the class described for a boiler having a water level responsive device and having a steam pressure responsive device, the combination of a member for controlling fuel input to said boiler, two actuators for said control member including a sleeve surrounding a rod, said rod being reciprocable relative to said sleeve to actuate said control member independently of sleeve motion, and operative connections between one of said devices and said rod and between the other of said devices and said sleeve.

2. In boiler control mechanism of the class described, the combination of a device responsive to a condition in said boiler, a member for controlling fuel input to said boiler, an actuator for said control member, and an operative connection between said device and said control member comprising a lever having an end oscillatable in the general direction of actuator movement, a springpressed plunger on the end of said lever and reciprocable endwise of said lever, a rocker lever having a fixed pivot intermediate its ends, one end of said rocker lever operatively engaging said rst named lever and the other end of said rocker lever operatively engaging said actuator, whereby said plunger and said rocker lever form a yieldable toggle adapted to snap to either side of dead center to hold said actuator in inoperative and actuated positions.

CHRISTIAN S. ANDERSEN.

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