US2274741A - Control apparatus - Google Patents

Description

March 3, 1942. H. A. ROL'NICK 2,274,741

CONTROL APPARATUS Filed Feb. 1, 1958 2 6" 0 f g 4' P 5 pa 6 6 B .INVENTOR HARRY A. ROLNlCK I swi ATTORNEY v pressure Patented Mar. 3, '1942 V r 2,274,741 I 7 CONTROL APPARATUS a 2,274,741 UNITED STATES PATENTIV'OFFICE,

, IlarryA, Rolnick, Philadelphia, Pa., assignor to i The Brown Instrument Company, Philadelphia,

Pa., a corporation of Pennsylvania 6 Claims The general object of the present invention is to provide improved control apparatus of the socalled air controller type, adapted to effect a control action automatically dependent upon a variable control quantity, by varying a control in predetermined accordance with changes in the control quantity. 1A more, specific object of the invention is to provide such control apparatus with improved means through which an initial fluid pressure change, resulting directly from a change in the control quantity, efiects an automatic adjustment of the control apparatus and thereby produces another and related change in the control pressure. 7

A still more specific object of the present invention is to retain certain characteristic advantages of, and to obtain certain advantages not obtainable with, air controllers of a type and form now in extensive commercial use, comprising a so-called flapper valve, adjusted in direct response to a change in a control temperature, pessure or other control quantity, tovariably throttle the discharge through a bleed nozzle, and thereby vary the pressure in saidnczzle, and comprising means through which said change in the nozzle pressure results in an immediate or quickly effected second adjustment of the flapper valve partially neutralizing the first mentioned vary the fuel supply rate in. accordance with through a pipe A., at a rate regulated bya-fluid pressure motor valve A which is" adjusted to changes in a fluid control-pressure, the latter being transmitted to they motor pressure chamture to which a fluid pressure thermometerbulb adjustment thereof, and a slowly eifected'third adjustment of the flapper valve in the same'direction as the original adjustment. Said second adjustment or its effect is commonly referred to as a follow-up adjustment or eifect, and saideffects by flapper valve adjustments. -My im-v proved air ccntroller preferably includes means for effecting follow-up adjustments of theflapper valve, which are mechanically separate and distinct from the means provided to secure the reset or compensating effects-,and which may be or. reset adjustment or omitted from themcntroller without, requiring any modification in the construction of, or interfering with the operative effect -of the last mentioned means. 7 r

The various features of novelty which characterize my invention are pointed out with particularity in the claims, annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying ber A of the valve A and being varied automatically by variations in the furnace temperab isexposed. ..In the particular arrangement shown and hereinafter described in detail, an increase or decrease in the temperature of the bulb Y results in an increase or decrease, respectivly, in the pressure transmitted to the valve chamber A and in a decrease Lorincrease, respectively, I

in the rate at which fuel is supplied to the furnace.

Bourdon tube helix B, and a shaftB' given a clockwise or counterclockwise adjustment by an increase or decrease, respectively, in the pressure transmitted from the bulb b. to the helix B. The shaft B carries a pen arm 3?, adapted to makea temperature record on'a scaled'record chart disc B The shaft B also carries an arm B? through which the angular adjustment of the shaftfBl resultingfrom changes in the temperature ofthe bulb b,, adjusts the control apparatus and there-,

by varies the control pressure in the chamber A ,The arm B operates through alink B connecting said arm to one arm of a floating bell crank lever 0, having an adjustablefulcrum pivot.

C-', and the second arm ofwhich carries a pin C engaging .one side of a flapper valveD. The

latter has a pivotal support D, and is spring biased to turn toward a cooperating bleed nozzle E, so that thefdischarge orifice in the latter is subjected to an increased or decreased throttling effect by a movement of the pin C to theright orto the left. 7 The fulcrum/pivot C' of the lever C, is carried by a lever F pivoted at F to a cham bered element G. The latter is normally stationary, but as hereinafter described, may be bodily adjustedfor a calibration purpose. The member G also carries the nozzle E, and the pivotal supf port D for the flapper va'lve D. V

The element G encloses a pressure space G havinga flexible wall portion. The latter is in the form of a bellows H having one end closed by an end wall H movable relative to the member G, and having its other end open and rigidly connected to the member G. As shown, the bellows H is subjected internally to the pressure of the atmosphere, and externally to the pressure in the chamber or space G so that an increase in the last mentioned pressure causes the bellows to contract, until the increase in the bellows contracting force is balanced by a. spring force which opposes the contraction of the bellows and increases as the latter is contracted. As diagrammatically shown, said spring force is wholly due to the resiliency of the bellows. The movable end wall H of the bellows H, is connected by a link I-I extending axially through the bellows to the lever F at a point between the pivots C and F. The bellowsI-I isa-follow-up device, operating as hereinafter described, in response to a pressure change inthe chamber G to efiect a follow-up adjustment of the flapper D which quickly follows and partially neutralizes each flapper adjustment efiected by angular adjustment of the lever C. j

The nozzle E is connected to a source of air under pressure, shown as pipe I, by a branch pipe I which includes a throttling or flow rethe port'K, and decreasing the throttling effect on the port K each of the twothrottling effect variations contributing to a resultant increase in the pressure in the chamber K. As shown, the

' valve'member K is connected to and adjusted by a lever L, which has a stationary fulcrum pivot L, and is biased by a spring L for movestricting device 1 the latter preferably including a needle valve or analogous element I which may be manually adjusted to vary the flow restricting efiect of the device 1 The pressure in the nozzle E and in the portion of the piping connecting the latter to the outlet of the device 1 thus depends upon the throttling effect of the flapper valve D, and is increased or decreased has a definite length for each value of its internal pressure.

The expansion or contraction of the bellows J in; response to an increase or decrease in the nozzle pressure, effects an increase or decrease, respectively, in the delivery pressure of a valve K. The latter, as shown, comprises an inlet chamber K connected to a source of air under pressure which may be, and as shown is'the pipe I, and which communicates through a port K with the delivery pressure chamber K of the valve. The chamber K bleeds air to the atmosphere at a rate depending on the adjustment of the valve member K which is adapted on its adjustment to simultaneously exert an increased throttling efiect on one, and a decreased throttling effect on the other of the two ports K and K The pressure in the chamber K is aptly termed the control valve pressure, because it is transmitted through piping K to the motor pressure chamber A of the valve A ,'to control the adjustment of the latter. It is also transmitted through the piping K to the chamber G, whereby changes in said pressure produce the previously' mentioned follow-up adjustment actions of the bellows H.

In the arrangement shown in Fig. 1, the elongatioriof the bellows J, resulting from an increase in the throttlingeffect of the flapper valve D, results in a down movement of the valve member K increasing the throttling efiect on ment in the direction to move the valve member K upward.

The elongation of the bellows J gives the lever L a counterclockwise adjustment through adjustable thrust transmitting means shown as compriisng parts M, N and J The part J is carried by the lever J and extends into engagement with the part N, which isan arm generally parallel to the levers J and L, and the part M is a thrust pin interposed between the levers N and L. Advantageously,for a reason hereinafter stated, the" part J is adapted to be adjustably clamped to the lever J in difierent positions along the length of the latter. The arm N is mounted on a pivot support N adjacent the end of the lever L to which the .valve member K is connected, so that the pin M is located between the pivotal supports N and L forrthearrn N and lever L. In consequence the leverage with which the lever J acts on the valve member K may be varied by adjusting the pin M longitudinally of the lever L and'arm N. To facilitate such adjustment, the pin M is carried by one end of a link M which is pivotally connected at its other end to an arm M pivoted to turn about a stationary shaft M and adapted to be held, as by friction, in any angular position into which it may be adjusted.

Mounted on the support J alongside the bellows J, is a second pressure responsive device 0, which, as shown, is a bellows similar to the bellows J. The bellows O has one end fixed to the support J and has its other end closed and movable, and pivotally connected to the second end of the lever J The control valve pressure is transmitted to the interior of the bellows 0' from the piping K, through a pipe 0 including a flow restricting device 0 preferably comprising a manually adjustable needle valve or analogous adjustable throttling element 0 r The parts are shown in Fig. 1, in the relative positions which they assume for' some particular stable operating condition, in :which the temperature of the bulb b remains constant at a predetermined normalvalue. 0n a-decrease in the temperature of the bulb b, the parts B C ,-J and K are given movements in the direction of the arrows respectively adjacent those parts, and on an increase in the temperature of the bulb, the said parts are given movements in directions opposite those indicated by the adjacent arrows. The movement of the pin C in the direction of the adjacent arrow, occurring as a result of a decrease in the temperature of the bulb b, moves the flapper D away from the nozzle E, and thereby immediately reduces the pressure in the chamber of the bellows J, which is in relatively free, or unrestricted, communication with the nozzle E, a

The resultant up adjustment of the valve member K increases the throttling of the port K and reduces the throttling of the port K and each of those throttling changes contributes to the resultant reduction in the control valve pressure in'the chamberK The reduction in that pressure, transmitted by the piping K 'to the valve chamber A results in an opening adjustment of the valve A thereby increasing the fuel supply to the furnace A, and tending to raise the furnace temperature to which'thebulb' bresponds, to its normal value. The decrease in the control valve pressure, transmitted by the piping K to the chamber G, results in an immediate elonand follow-up adjustments of the flapper valve.

D, resulting from the described decrease in temperature of the bulb b, is a reduction in the pressure in the bellows J and a corresponding reduction in thecontrol pressure maintained in the chambers K A and G and piping K This reduction in the control pressure is transmitted to the pressure responsive device at a slow rate, due to the eiTect of the flow restricting device O As the pressure in the bellowsO is thus'reduced, that bellows contracts, and the valve member K is given a further adjustment in the same direction as that produced by the previous contraction of the bellows J. o

. Operations which are the converse of thosejust described result from an increase in the temperature of the bulb b following a steady operating condition in which the control parts have come into a condition of equilibrium. As those'skilled in the art will understand, while the normal and ultimate average effect of an increase or decrease in the temperature of thebulb b is a corresponding quick adjustment of the control pressure in the corrective direction efiected by the change in length of the bellows J and adelayed adjustment of the control pressure in the same directioneffected through the bellows O, with relatively rapidly alternating increases and decreases int-he temperature of the bulb, the bellows 0 may either slowly contract or slowly expand during a period immediately following either a contraction or an expansion of the bellows J. However, when the resultant of rapidly recurring bulb temperature fluctuations is an increase or decrease, the ultimate resultant effect of the operation of the device O is to augment the effect on the control pressure produced by the ultimat resultant effect of the bellows J. The bellows 0 thus serves the normal intended purpose of compensating adjustment means, in that it compensates for load changes in the controlled system. Thus in the furnace control system shown in Fig. 1, the bellows ,0 causes the valve A to be more widely open for a given bulb temperature, during any extended period of operation in whichthe furnace load is relatively heavy, and the need for fuel correspondingly large, than during anextended period in which the furnace load is relatively light and less fuel is needed.

The. apparatus diagrammatically illustrated in Fig. 1 is characterized by its relative simplicity and inherent operative reliability and by the ease with which desirable adjustment may be provided. Thus, as shown, in Fig.1, the relative effects of the pressure responsive-devices Jand O on the adjustment of the valve member'K and on the control valve pressure, may be varied by adjusting the thrust part J 3 along the length of the lever J Furthermore, with any given adjustment of the part J the throttling range of the control apparatus, or range of variation in the and arm N: An adjustment of the pin M-to the right increases, 'and its-adjustment'to the left control valve pressure produced by a given change in the pressure transmitted from the nozzle'E to thebellows J."

The type of apparatus-shown" in Fig; 1 is advantageously characterized further, by-the flexinozzle" pressuretransmitted to the bellows J decreases the m'agnitudeof the change in the.

bility which it permits in the design and assembly 'ofapparatus operating in accordance with the principles of the invention: Thus for example, the size and inherent elasticity of each of'the bellows devices J and O employedfm'ay'be determined with specialreference to the particular conditions ofuse, and inthe actual production of a commercial instrument; the latter may be assembled for use under particular operating conditionsj by suitable selection from stock inclu'd- Q ing interchangeably usable bellows 'parts'of dif ferentfdimensions and resiliency. Thev'alve K- '1 is adapted, desirablyincludes" means for vary 1 ing the control setting point, or'valu'e of the control quantity which the a'pparatus tends to maintain; One known arrangement for f the purpose is illustrated in Fig. and comprises means for bodily adjusting the member G- about a supporting pivot- G' so asto thereby change the relativepos'itions of the flapper D and nozzleE. with a given position of the arm B adjustment, the'member G'is shown as formed with a gear segment G engaged by a manually As shown,-the rotation of the worm P also'angularly adjusts a gear segment Q pivoted at Q and connected by a link Q to an index Q pivoted on, or coaxially with, the shaft B',-and adapted to indicate'on the chart B the temperature of the bulb b In the modification shown in Fig. 2, the pipe 0' with its flow restricting device 0 does not connect the bellows O to the pipe K, but to 1 contract and elongate, the bellows O corresponde ingly' elongates and contracts, respectively. The

arrangement-shown in Fig.2 has'the advantage over that shown in,Fig. 1 in 'that it is practically possible to more readily a'nd'accurately regulate the flow through a restricted passage of a' liquid than of an elastic fluid as air.

To effect such rotatable worm P supported in the-bearings P.

which the apparatus tends to main- While in accordance with the provisions of the statutes, I have illustrated and described the a best form of embodiment ,of1my invention now knownto me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features. Y

Having now described my invention, what I claim as new and desire to securev by Letters Patent, is: A 1 c 1. In .air control apparatus, the combination with a pressure responsive device, of means,-comprising an adjustable valve mechanism and means responsive to variations in a control quantity for adjusting said valve mechanism, for subjecting said device to a pressure varying promptly and in predetermined relation with -variations in said control quantity, means including a second adjustable valve mechanism for maintaining a control pressure dependent on the adjustment of said second valve mechanism, a second means to adjust said first valvemechanism, a non-restricted flow passage. through which changes in said controlled pressure operate said second adjusting means to adjust said first valve mechanism in a direction opposite to the movement imparted to it by the control reisponsive means, a second pressure responsive ldevice, means including a restricted flow passage through which changes in said control pressure are slowly transmitted to said second responsive device, and levermechanism separate from said first mentioned valve mechanism actuated jointly by the two pressure responsive devices to directly adjust said second valve mechanism in prompt response to a change in the pressure to which the first mentioned responsive device is subjected, and to effect a retarded adjustment of said second valve mechanism on a change in said control pressure ina direction augmenting control pressure.

3. Apparatus as specified in: claim 1,- including means for varying the relative adjustment effects of the two pressure responsive devices on said second valve mechanism, resulting from a change in the control quantity.

4. Apparatus as specified in claim' 1, including means for ,varying the magnitude of the control pressure change produced by a given' change in the pressure to which the first mentioned device of claim 1 is subjected.

5. In air control apparatus, the combination with a pressure responsive device, of means, comprising an adjustable valve mechanism and means responsive to variations in a control quantity for adjusting said valve mechanism, for subjecting said device .to a pressure varying promptly and in predetermind relation with variations in said control quantity, means including a second adjustable valve mechanism'ior maintaining a control pressure dependent on the adjustmentiof said second valve mechanism, a" second means to adjust said first valve mechanism, a non-restricted flow passage through which changesin said control pressure operate said second adjusting means to adjust said first valve ,mechanism in a direction' opposit e to the movement imparted to it by the .control responsive means, a second pressure responsive device, means including a, restricted 'fiow passage, through] whichchan'gesjin said'control pressure are slowly transmitted to said second responsive device, and means cooperating with the two pressure responsive devices to adjust said second valve mechanism in prompt response to a change in pressure to whichthe first mentioned re-' sponsive device is subjected, and; to effect a retarded adjustment of "said second valve mechanism on a changein said control pressure in a direction augmenting the last mentioned change, each of, the pressure responsive devices being an. expansible container subjected internally to the corresponding pressure and both containers acting on saidsecond valve mechacomprising an adjustable valvmechanism and means responsiveto variations in a control quantity for adjusting said valvemechanism, for subjecting said device to a pressure varying promptly and in predetermined relation with variations in said control quantity, means ineluding a second adjustable-valve mechanism for maintaining a control pressuredependent on the adjustment of said second valve mechanism, a second. means to adjust said first valve mechanism, a non-restricted flow passage through whichchanges in said controlpressure operate said second, adjusting means to adjust said first valve mechanism in a direction opposite to the movement imparted to it by the control responsive :means, a second pressure responsive device, means including a restricted fiowpas sage through: which changes in said control pressure are slowly transmitted to said second responsive device, and means cooperating with the two pressure responsive devices to adjust said second valve mechanism in prompt response to a change in the pressure to which the first mentioned responsive device is subjected, and to efiect'a retarded adjustmentof said second valve mechanism on a change in said control pressure in a direction augmenting the last mentioned change, each of the two pressureresponsive devices being bellows elements located alongside of one another and each having one end stationary and tthe other end movable and connected to the corresponding end of a floating lever. means operatively engaging said lever intermediatelits' ends through which the expansion of either b llows produces an adjustment of the second valve mechanism in one direction. and contraction produces an adjustment on the opposite direction and in which the pressure first. mentioned is transmitted to the interior of oneflof said bellows .and the control pressure is transmitted HARRY AgROLNICKr

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