US1854922A - Control apparatus - Google Patents

Description

April 19, 1932.

E. S. BRISTOL CONTROL APPARATUS Original Filed Dec. 18, 1924 2 Sheets-Sheet l April 19, 1932. E. s. BRISTOL 1,854,922

CONTROL APPARATUS Original Filed Dec. 18, 1924 2 Sheets-sheet 2' Zia/621102" G x! M P2 f Maw Patented Apr. 19, 1932 PATENT OFFICE EDWARD S. BRISTOL, OI PHILADELPHIA, PENNSYLVANIA, ASSIGNOBJIO LEEDS G2 NOBTHBUP'GOIPANY, OF PHILADELPHIA, PENNSYLVANIA, A OORPOBATION OI PENNSYLVANIA comnor. Arrm'rus Original application fled December 18, 1924, Serial No. 756,856. Divided and till: application filed September 21, 1929.

having advantages over the various construc- B tions proposed heretofore as regards simplicity and ruggedness of construction, sensitivity and reliability of operation, and adaptability to different machines, equipment or a device or element to be controlled in accordance with varying conditions.

Other objects and advantages will hereinafter appear.

For the purpose of illustrating theinvention, several embodiments thereof are shown in the drawings, wherein Figure 1 is a diagrammatic view, partly in section, showing the manner in which apparatus'constructed in accordance withthe present improvements may be embodied in a control'system for a steam generator; 7

Fig. 2 is a diagrammatic view, partly in section, showing a modified construction of apparatus embodying the present improve- Fig. 3 is ,a side elevational view, looking toward the left in Fig. 2; and

Figs. 4, 5, 6'and7 are diagrammatioviews illustrating, respectively, other modified constructions of apparatus embodying the present improvements.

"Referring to Fig. 1, B is a steam boiler or generator comprising a drum D in communication with the water tubesT, which latter are disposed in a heating chamber comprising the furnace or fire chamber F' from which the hot gases ass around the tubes T and thence outwar 1y throu h the stack S provided with the damper operable by hand or automatically throughthe pivoted lever a [provided with the counterweight b and the actuating or control cord or chain. 0.

Steam is delivered through the line or conduit C to steam turbines or engines, or other steam-consuming devices. Steam is supplied through the pipe 0 to the engine or motor f, which drives the stoker g which delivers fuel 7 to the fuel-bed hdisposed upon the grate z' upwardly through which and the bed h air is supplied at varying rate by the air blower A Serial No. 394,366.

driven by any suitable means, as, for example, the electric motor M, which is in turn controlled in response to variations in the pressure of the steam delivered by the generator Connected with the conduit G is the pipe 7', through which the steam pressure is applied to the interior of the chamber k closed by the v flexible or yielding diaphragm m, upon which 15 carried the knife edge or pivot n, upon which rests the lever or beam 0 provided with the pivot or knife edge 11 en ging the under side of the abutment g. ovable along the lever o is the member 1, which may be socured thereto in any of its adjusted positions by the set screw 3. Pivoted to the fixed member t at u is the lever 1r, along which is movable the member '10, which may be secured in any of its adjusted positions by the set screw The link :1 is pivoted at its opposite ends to the members -r and 10, whereby movements or deflections of the lever o are imparted to the lever v. By adjusting the members'r and 'w to different positions along their respective levers o and 'v, the ratio of angular movements of the levers o and 'vis variable or adjustable for the purpose of varying with respect to the pressure change effective upon the diaphragm m the magnitude of the resultant control effect, as, for example, control of the speed of the motor M and therefore control of the rate of combustion in the generator B.

Opposing the pressure applied to the under side of the lever o by the diaphragm m is the weight .2, hungby the knife edge a1 upon the lever o. For operating cumulatively with the weight 2 upon the lever 0 there may be utilized the spring b1, connected at its one end to the lever o and at its opposite end to the member t, the tension of the sprin bein adjust-able by the screw 01. The e ect o the spring b1, if and when emplo ed, is to reduce the extent of motion or de ection of the lever o fora given change in steam pressure, with the result that larger pressure changes are required to produce a given magnitude of COIilIII'Ol efiect. h l d t;

un upon t e ever an 0 re. mg thereon 'cumulatively with ither or bbth the ample, 245 to 255 pounds weight a andspring 61, is the tank or chamber (51 connected by the flexible tube e1 through the throttling valve fl with the stationary or fixed chamber g1 having the vent hl to atmosphere. In the chambers g1 and (Z1 is contained liquid all, which may be of any suitable character, as water, oil, etc. The spaces in the chambers (Z1 and g1 above the liquid therein are connected through the flexiible tube jl. 1 f

Carried by and insulated from the lever o is the movable contact k1 of a rheostat comprising the resistance ml, the amount of which in circuit is increased by downward movement of the contact 701. The direct current shunt motor M receives its current from the supply conductors a1 and 01, across which are connected the motor armature and motor field, the adjustable resistance m1 being connected in series with the motor field through the conductors p1, g1, whereby the field of the motor M is weakened or strengthened as the contact 701 descends or' ascends, effecting corresponding increase or decrease or" speed of the motor M, and therefore of the blower A, and thereby increasing or decreasing the rate of combustion of fuel'in the generator B.

While the Weight 2, spring 51 and chamher all are shown as applied directly to the lever o, it will be understood that any one or more of them may be applied to the lever v to apply thereto a downward force to the left of its pivot at. And it will be understood that these members, or equivalents of them, may be similarly applied to the secondary levers corresponding with lever 42 of any of the other arrangements hereinafter described.

The operation of a'system of the character illustrated in Fig. 1 is as follows:

Assuming that the standard or reference pressure of the steam delivered through the conduit C shall be, for example, 250 pounds per square inch, the normal control, that is, the control effected by the lever 0 'under the control of the diaphragm m and either or both the weight a and spring the chamber (11, or without change in the amount of liquid therein, will, for changes of load within suitable limits, maintain the boiler pressure within therange of, for exper square inch. Upon occurrence of load or increase of load upon the generator B, the pressure will fall, for example, to 24.7 pounds. There will be a co1-esponding reduction in pressure in the chamber 70, and the diaphragm m will yield downwardly to corresponding extent because of the now preponderance of control upon the lever o by either or both'the weight 2 and spring 721. In consequence, the contact 101 descends, cutting resistance into the field of the motor M, and thereby correspondingly increasing the speed of the blower A and the rate of combustion. er A effected by the aforesaid descent of conof the lever 0.

61, but without The speed of'the blow-- messes tact 701 may be such as to increase the rate of combustion to such magnitude that during the persistence of the same load which caused the descent of the diaphragm m the steam pressure of the generator will be maintained at the aforesaid magnitude of 247 pounds. Such normal control may effect, as stated, the maintenance of the steam pressure during persistence of load at the subnormal pressure of, say, 2 .7 pounds, or the adjustments or proportions may be such that the rate of combustion will permit the steam pressure to further slowly or slightly decrease or slowly or slightly increase with respect to 247 pounds. When equilibrium is attained, with the speed of blower A just sufiicient to maintain combustion at the rate required by the increased load, the steam pressure will become stabilized at the value necessary to hold contact 761 at a position corresponding with the increased speed of motor M.

The action or the chamber (Z1, however, is to vary the normal control by superimposing thereon a compounding control, efi'ective immediately the lever 0 deflects. The 5111331 posed or auxiliary control is direct, in the sense that it is dependent directly upon the deflection of the lever 0, and not indirectly upon any force due to or representative of a change ei'lected through the normal control More specifically in the example illustrated, the superposed or the compound control is etl'ected by flow of liquid through the throttle valve fl and tube 61 into the chamber 611, thereby applying greater weight to the lever 0. This bias or force is therefore directly applied, and directly and immediately in response to deflection of the lever 0, and in this instance greater as the deflection of lever 0 is greater; it is not due indirectlyto the effect of the control, as of the blower A or any other steam-pressure-changing means, as effected in response to deflection When the lever arm 0 finally attains equilibrium after a change of load, the superposed control has acted to change the loading Weight on lever 0 in a predetermined manner, so that the steam pressure attains a predetermined value for each position of the regulating mechanism.

Because of the increased weight applied to the lever 0 by the liquid passing from chamber g1 into the chamber all, the control is compounded in the sense that notwithstanding the persistence of the load upon the generator B which caused the fall in steam pressure, the speed of the blower will be such as to effect a rate of combustion more than sufficient to maintain the steam pressure at 247 pounds, and will cause it to rise or return to 250 pounds; or the control may be over-compounded and cause a rise in the steam pressure during the persistence of the load to a value even higher than 250 pounds. The nature of the compounding action is predeapparatus.

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termined as desired by suitably fixing the size and shape of the chambers J1 and g1.

The effect of the superposed or compounding control is, therefore, to cause an amplification or exaggeration of the normal control to effect the application of an agent, such as an agent affecting the rate of combustion in the example illustrated, or any other condition or factor upon whose magnitude depends the magnitude of the steam pressure.

The throttle valve fl is provided to prolong or retard the flow of liquid from chamber 91 into chamber'dl upon deflection of the lever or to delay or retard the flow in reverse direction from chamber d1 into chamber 91 in event of steam pressures above the standard or reference pressure, or within the upper part or beyond the upper part of the range of pressures within which the normal control is by itself effective. By prefer- .ence, the valve fl is so nearly closed as to introduce a considerable time factor as re-' gards the application of the superposed or auxiliary control to prolong. the desired steam pressure change throughout a period of, for example, ten to fifteen minutes, more or less." While for purposes of illustration I have described the control of the rate of application of air to a combustion chamber of a there disclosed may be used in a system such as indicated in Fig. 1, or in a system of any other character above referred to for controlling the magnitude, rate of application or position of a control agent.

Referring to Figs. 2 and 3, there is illustrated an arrangement in which along the secondary lever '11 is adjustable the member 11, to which there is pivoted the link 81 pivoted at its upper end to the member t1 adjustable along the member ul carried upon the piston rod '01, upon which is secured the piston wl movable in the cylinder 001. To the rod '01 is connected also the chain c, which, as indicated in Fig. '1, is utilizable for varying the position of the damper d to thereby vary the rate ofcombustion of the generator B, as when natural draft is used, or as when forced draft is supplied-so as to maintain a desired pressure in the furnaceF,

as will be understood by one familiar with the art. The lower and upper ends of the cylinder :01 are connected through the passages 3 1 and 21, respectively, with the upper and lower ports a2 and 62 of the pilot valve structure comprising the chamber 02, in which is movable with respect to the ports a2 and b2 the slide valve (12 operated by the rod e2 pivoted to the lever 11 at f2. Fluid under pressure, as steam, air, water, etc., is delivered through the pipe 92, and. directed accordin to the position of the valve d2 into the cyFinder $1 on one side or the other of piston wl, the fluid being exhausted through the exhaust or discharge outlet h2.

B the adjustment of the members 11 and t1 ai ong the lever v and member ul, respectively, the distance between the pivot f2 and the pivotal mountingof the lever '0 upon the member t1 through the link 81 is varied to.

procure any suitable ratio of movement of the slide valve d2, whose movement is further affected by the ratio of movements of the levers o and 'v as determined by the positions of the members r and w upon the levers 0 and '0, respectively.

In general, the operation is similar to that descri ed in connection with F i 1, in that the flow of liquid from chamber 91 into chamber (11 upon downward deflection of the lever 0 effects a superposed or amplified control causing the plston wl to move in such a direction, and to'such extent asto move the damper d in such direction and to such extent as to efiect a rate of combustion which may be such either'as to maintain the pressure corresponding with the increased load, or as to cause such pressure to rise and return to or beyond the standard or reference pressure.

- The piston ml by its motion reacts through the lever 41 upon the valve d2 to return it to or toward its port-closing position. In the example illustrated, a'downward deflection of the lever 0 causes upward movement of the piston wl and of chain c, and reacts upon 1 the valve (12 to return it upwardly toward or to port-losing position.

With structure of this type there is a definite position of the piston wlcorresponding to any position of the arm 0 within the working range. The use of the piston wl and its adjuncts of the character described may, as indicated, be utilized in lieu of the motor M and its control, of Fig. 1, or of Figs. 4 to 7.

Referring to Fig. 4, there is shown control apparatus utilizable in systems of the character described in connection with Fig. 1, and in which again there. is provided a superposed or auxiliary control directly responsive to change in the pressure to be controlled.

There is applied to the system which deflects in response to pressure changes a superposed or auxiliary control force by the spring '52 connected to the deflecting system to operate cumulatively thereon with either or both ''ing over suitable idler rollers and connected to the nut 722 through which is threaded the shaft me, upon which is secured the worm gear n2 driven by the worm 02 secured upon the shaft of the reversible electric motor M1 receiving current from the supply conductors p2'and 92, in which latter is disposed the ly, the adjustable contact-e002 and 2 connected, respectively, ,in the leads of. the different field windings of the motor M1, whereby when the contact s? is in engagement with contact m2 the motorllfrotates in one direction, and in the. opposite fdirection when the contact 82 engages the contact g 2,.in which latter case the nutjcZis moved-downwardly to increase the tension upon the spring z'2 and thereby increase the force acting downwardly upon'the lBVGlflOp The gear ratio as between the shaft of the motor M1 and the nut 702, and the mag nitude of the resistance r2, are such'that the nut c2'moves fslo.v. ly, thereby introducing a time factor or lag as regards application of the auxiliary or' superposed control, as effected in the arrangement of Fig. 1 by the throttle valve f1. i

As the ,nut 702 descends, the increased force applied downwardly upon the lever 0 increases the loading force when the pressure falls, and, vice versa, decreases the loading force when the pressure rises, in which latter case the nut Z02 ascends because of engagement of the contact 52 with contact The contacts 022 and p52 are yieldingly mounted, so that notwithstanding relatively great displacements of the lever 0 there shall not be offered thereto appreciable opposition.

Obviously, the contact 82 may be carried upon the lever 'v, or upon any other member moving in unison with the diaphragm m.

In Fig. 5 there is shown a generally similar arrangement, but in this case the block 142 remains stationary and the nut k2 carries a pivot 10 for the lever 41.

Upon drop in pressure, the downward defiection of the lever 0, which tends tobalance in a horizontal position when. equilibrium is attained, closes circuit at the contacts 32 and 3 2, causing the nut 1:2 to ascend, causing a drift or shift of the contact 701 with respect to the fixed resistance m1, and having in general the effect of superimposing a direct auxiliary control, of the character effected by passage of fluid from chamber 91 into chamber (Z1 in Fig. 1. The auxiliary control is again effected slowly, as in Fig. 4. Nhen the pressure is returned to standard, lever arises to ahorizontal position, circuit is opened at the contacts 82 and 3 2, and the superimposed drifting action ceases.

To prevent travel beyond the control range, there are provided in the circuits of the contacts and g2 the limit switches 22 and a3,

' respectively. The limit switches are opened after predetermined extent of movement of the nut k2 by the member 63 movable therewith, or may be actuated by contact 701, as

the extremes of travel of contact #1, or may be opened after predetermined travel of the nut Z22, as described in connection with Fig. 5.

In this arrangement again there is effected a drifting motion of the contact k1 in one sense or the other, according to the sense of deflection of the levero, and this dr ting motion, as in Fig. 5, effects a direct and immediatelysuperposed or auxiliary control having the purpose and effects-hereinbefore described.

In Fig. 7 there is again shown a generally similar arrangement. In this instance,.however, the resistance m1 is moved by.v the nut k2 with respect to the contact 701 upon deflection of the lever 0 to effect the direct superposed or'auxiliary control.

While but a single steam generator has been described as controlled, it will be understood that any number of them may be simultaneously controlled by one and the same mechanism in response to their common steam pressure. In such case the blower A may supply air for all of the generators of the battery, or each generatormay have its own blower A driven by its individual motor M,

in which case several rheostats Z01, m1 may be operated in unison by the control mechanism, as, for example, by the member 0 thereof. Or in the case of the arrangement indicated in Figs. 2 and 3, the several stack dampers d of the different generators, or at least different furnaces, may be moved in unison by the piston wl.

This application is a division of my copending application Serial No. 756,856, filed December 18, 1924. I

From the foregoing it will be seen that improved control apparatus has been provided including means, such as the fluid-pressure motor E's-m and lever 0 responsive to variation in conditions to which the apparatus is subjected, such as variation in steam pressure conditions of boiler B in the system shown in Fig. 1, such means being operable to effect controlling action of the apparatus through a control range corresponding to such variation. Further, it wilhbe seen that the apparatus includes means, such. as chambers 91 and d1 in Figs. 1 and 2 and nut 102 in Figs. 4 to 7, rendered eflective consequent upon operating action of motor lcm and the associated lever 0, and being operable upon -be-' coming'efi'ective' to induce controlling action of the apparatus beyond the control range efiected by operating action of the motor and lever 0. While the various modifications or arrangements shown and described are presented as practical embodiments of thepresent invention, it is to be understood that various other changes or modifications, such as in the size, shape or arran ement of the parts, might be made without departing from the spirit of-the invention or. the scope of the c alms. 5

The invention claimed is: v

1. In control apparatus, pressure responsive means includinga movable member, a resistance, a contact adjustable along said resistance, structure mechanically connecting said movable member to said adjustable contact for movement thereof at a rate of departure of pressure from a predetermined controller immediately and substantially proportionally responsive to pressure changes; and auxiliary control means for gradually applying a controlcumulative with and con-. tinuing for a substantial period after said primary control comprising a motor and speed-reducing means -for slowly efl'ecting relative movement of-said contact and said resistance, and switch mechanism operated by said member to control said motor.

2. In control apparatus, a deflecting member responsive t the controlled condition, a resistance, a. pivzted contact therefor, a link connecting said. member and said contact, structure forming an adjustable fulcrum for said pivoted contact, a motor and speed-reducing means for, adjusting said structure, and contact mechanism operable by said member for controlling said motor.

3. In control apparatus, a deflecting member responsive to the controlled condition, a

resistance, a" contact therefor, structure' mechanically connecting said member to said contact, and means operating upon said structure to vary the, distance between said member and said contact to efle'ct a compensating control comprising a motor, speedreducing means, and contact mechanism operable by said deflecting member for controlling said motor. v

5. In combustlon control apparatus for vapor generators, means responsive to pressure including a deflecting member, a prlmary control system for controlling the combustion rate, com-prlsing aresistance and an ad ustable contact mechanically connected to said deflecting member for movement in immediate response to pressure changes, and means for effecting a supplemental control of the combustion rate to compensate-for the falling characteristic of the system comprising a motor, speed-reducing means, contacts operable by said deflecting member to control said motor, and means mechanically connect- "ing said lever to said contact arm, a spring connected to said lever for opposing move-' ment by said diaphragm, and means for varying gradually the tension of said spring to effect compensated control of combustion comprising a motor, contacts adapted to be operated by said weighted lever and mounted on a movable support, and speed-reducing means interposed between said motor and said spring and between said motor and said contact mounting. i

. 7. In combustion control apparatus for vapor generators, means responsive to the vapor pressure including a deflecting member, a primary control system for controlling the combustion rate, comprising a resistance and an adjustable contact mechanically connected to said deflecting member-for varying said resistance in immediate response to pressure change, and means for effecting a supplemental control of the combustion rate to compensate for the falling characteristic of said system comprising a motor, speedreducing means, contacts operable by said deflecting member to effect a control of said motor, and means. mechanically connecting said speed-reducing means to said primary control system gradually to eflI'ect further change of resistance in the same sense as effected by the primary control but beyond the final value possible by action of the primary control. i

8. In control apparatus, pressure responsive means including a movable member, an adjustable resistance for controlling the magnitude of said pressure, means for promptly checking change of said pressure from a predetermined value comprising means interconnecting said movable member to said adjustable resistance for variation thereof at substantially the rate of departure of said pressure, and means for gradually restoring the pressure by further and slower variation of said resistance comprising a motor, speedreducing means interposed between said motor and said adjustable resistance, and mechanism operated by said member to effect a control of said motor. I i

9. Incontrol apparatus, a-deflecting mem ber responsive to the controlled condition, a

variable resistance for controlling said condition, means, for promptly checking departure.

of said con-trolled condition from a predetermined value comprising means interconnecting said movable member tosaid adjustable resistance'lto effect variation. thereof at substantially the rate of departure of said condition, and means for graduallyrestoring said condition by furtheran'd slower variation of said resistance comprising a spring connected to said member, a motor and speed-reducing means for continuously and gradually changmg the tension of said spring 1n a sense resulting in further movement of said deflect- I ing member always in the same direction as the initial movement of said member in response to departure of the condition, and switching mechanism controlling voperation of said motor comprising movable contact structure operated by said deflecting member and cooperating contact structure slowly movable in the path of said first contact structure by said motor and speed-reducing means.

10. In control apparatus for a vapor generator, vapor pressure responsive means including a deflecting member, a combustion control member, structure connecting said deflecting member to said control member for effecting change in the rate of combustion substantially immediately to an. extent deter mined by the extent of departure of the vapor pressure, and means for gradually restoring the vapor pressure comprising a slowly acting motive mechanism for effecting change in the position of said control. member, and means engaged by said deflecting member to initiate operation of said motive-mechanism and disengaged'from said deflecting member upon restoration of the vapor pressure to stop operation of said motive-mechanism.

EDWARD S. BRISTOL.

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