Патент USA US2301301код для вставки
2,301,301 Patented Nov. 10,. 1942 UNITED STATES " PATENT OFFICE Robert L. Mallory, Houston, Tex., assignor to The ' Brown Instrument Company, Philadelphia, Pa., . .a corporation of Pennsylvania Application October 7, 1939, Serial No. 298,419 7 (c1. rev-439) ' understanding of the invention, however, its ad My present invention comprises improvements ogous control actuating element and which varies vantages, and speci?c objects attained with its ' use, reference should be had to the accompanying drawing and descriptive matter in which I have illustrated and described a preferred embodiment in accordance with changes in a control condi- ' of the invention. in ?uid pressure control apparatus operating to create a control ?uid pressure force which is im pressed on a ?uid pressure control motor or anal ' ' In the drawing: ‘ > ' tion, such for example, as a temperature, a pres Fig. 1 is a diagrammatic view, partly in section, sure, a height of liquid level, or a velocity, the, showing one embodiment of my invention; controlling condition usually, though not neces~ Fig; 2 is a view, partly in section of a second sarily, being returned to, or-toward a normal 10 - value on a departure therefrom, by the operation _ embodiment; and Fig. '3 is a view of an embodiment having an of said motor or analogous device. ~ other arrangement of the control nozzle. Referring to the drawingthere is shown by A main object of the present invention is to provide certain speci?c improvements in ?uid pressure controlling apparatus of the type com 15. way of example, a furnace l whose temperature is to be controlled. The temperature of the fur prising means whereby a departure in the value nace is to be varied by regulating the heating of a controlling condition from a predetermined ?uid therefor which is supplied through a pipe or normal value thereof, varies an air or other 3 having a valve 4 in it. The valve is closed by ' elastic ?uid pressure control force, and whereby such initial variation in the control force pro duces a second control force adjustment quickly eliminating more or less of the initial change in the‘control pressure, and produces a subsequent means of the pressure of a spring 5 and is opened . varying amounts in response to pressure applied to the h .per surface of a diaphragm 6. Inserted in the furnace is a temperature re- ' sponsive bulb ‘I that is ?lled with a ?uid that of the second adjustment isneutralized at a rate 25 expands upon an increase in temperature to cause third control force adjustment by which the effect ' suitably retarded to insure the regulation or con trol stability necessary to avoid hunting. Said second and third adjustments are sometimes referred to as “follow-up” and “compensating” adjustments, respectively, and the third adjust ment is also sometimes referred to as an auto the expansion‘ of a Bourdon tube 8 to which it ' is connected by a capillary 9. The Bourdon tube 8 is of helical form and has its stationary end attached to the capillary 9,‘ while its'movable end is attached to and adapted to move a lever l0 clc‘kwise around a pivot II in response to . temperature increases and to move said lever ' counter-clockwise in response to temperature In such control apparatus, the extent to which decreases. 7 theinitial control pressure adjustment is neu tralized by the second adjustment, and the rate 35 Through suitable connections the operation of at which the third adjustment ‘neutralizes the ' the lever l0 gives motion to a ?apper valve I2, which as shown, forms part of a control pressure effect of the second adjustment, should be capa regilator, or air control unit It, and regulates ble of regulation or calibration to enable the the escape of air therefrom, and thereby regu apparatus to give desirable results under varying 40 lates the control air pressure in a regulator conditions of operation. chamber I4, The latter receives air through a .Another main object of the present invention pipe I5 and a restriction 16. The pressure in is to provide an air control instrument by which matic resetting adjustment. the above mentioned movements are accom plished in a simple manner by the use of an abso lute minimum of parts. In my invention a single ‘ bellows that is subjected to variations in air pres sure on its opposite sides as a result of'a change in the value of the condition being measured and I. the chamber I4 is transmitted through the pipe l5 to the control chamber of a booster valve l1. Booster valve H is supplied with air under regulated pressure from pipe l8 to a controlled pressure chamber i9. Pivoted within the cham ber IB' and attached to a diaphragm 20, forming one wall of the control chamber, is a valve 2i controlled is used to operate mechanism that provides the follow-up and compensating move 50 that moves between the air entrance of pipe “I and an exhaust duct 22. Diaphragm 20 is sub ments. ' ' . The various features of novelty which charac terize the present invention are pointed out with particularity in the claims annexed to and form ing a part of this ‘specification. For a better 55 jected to opposing pressures, namely that in chamber M and that in chamber I9 to ‘move the valve‘2-l between the inlet and exhaust openings to thereby maintain the pressure in chamber l9 2 1 proportional to that in chamber ll. A pipe II connects the chamber is to the control valve 4. All of the above mentioned parts except the furnace I, valve 4 and bulb ‘I, are advantageously proportional to the temperature increase in the combined in a control instrument which 'may well be a recording meter similar in form to a initial temperature change results from and is commercial type meter used for recording tem peratures and pressures. Such a meter may include a casing, chart plate, chart, and chart driving motor together with a hinged door, which reduction in chamber H. Due to the pressure reduction in chamber I l the bellows 48 expands simultaneously shifting rod 48 to the right. As the rod 48 moves the member 38 is also shifted to the right so that bell-crank 34 and pin 33 for sake oi clearness, are ‘not shown herein. v furnace. ' * The second or follow-up movement oi.’ the in strument that is produced as a result of the practically contemporaneous with the pressure‘ will let the ?apper return toward its initial posi tion, thus tending to neutralize the original pres sure change. The net eilect oi the initial and ‘ment thereby in accordance with temperature 15 iollow-up adjustments following any particular departure of the pen from its normal position changes in the furnace. An arm 28, extending from the pen arm 25, is connected by a link ' is a corresponding definite change in the control pressure and a‘ corresponding de?nite position 28 to one end of a ?oating lever 38 that is nor mally pivoted at its right end. The ?apper I: for the valve 4. that is pivoted at ll, on a support 32 extend 20 In order to compensate for the temperature _ increase to bring the value of the iumace tem ing from the control unit II, is given movements proportional to the temperature changes of the perature back to the control point, the instru furnace I by means 01' a pin 33 that is project ment, as a‘ result of its second movement, is ing from One arm of a bell-crank lever 84 which . given its third or compensating movement. As has its other arm pivotally connected to the 25 the bellows 48 expands due to a decrease in pres center or lever 38. The bell crank 34 is sup sure in the chamber H the volume of chamber 4| will increase and decrease the pressure in ported tor movement at 38 around the lower that chamber. This pressure change in the end of a lever 38 that, along with the ?apper The meter recording pen 28 is mounted on the lower end of an arm 2!, pivoted at 28, and con nected by a link 21 to the lever N for move is pivoted at 8|. - _ chamber 4|, however, is so small as to be negli The unit It comprises a cup-shaped casing 30 gible, so that the pressure in that chamber is still considerably above the reduced pressm'e in member 31 that is closed by a head 38. Pro iecting from the head is a nozzle I! which com chamber It. The air in chamber 4| therefor starts to pass through the duct 48, at a rate municates with the chamber‘ l4 and is variably controlled by the adjustment of restriction 48, throttled by the ?apper valve l2. Within the casing 31 and attached to the head 88 is an 35 into the chamber H. As this continues pres sures in the chambers II and It are equalized extensible bellows 48 that has a rod 4! attached and the bellows 88 returns approximately to its at. one end to its head; the other end of the normal length moving the ?apper away from the rod being pivotally connected to the member nozzle or toward-its original position, again re'38. The head 89 is provided with an opening through which the rod 88 extends, this opening 40 ducing the pressure hi chamber ll. Bellows 88 being. in effect, closed to form a second chamber‘ at the termination of the compensating action. ‘will be displaced from its initial position by an 4! by another and smaller sealing bellows 82. ' amount depending upon the amount of air which The sealing means for chamber 4| is conven is transferred from chamber ll to chamber l8 iently shown as the small bellows 42, but may, if desired, take the form of a limp diaphragm 45 during the interval that the bulb ‘l was above its normal value. This is in turn dependent upon or an ordinary stu?'lng box. The bellows I2 is the original pressure change in chamber I 4 and attached to the rod 80 so that the two bellows 48 and I! move together as the bellows 88 is the relative areas of bellows l8 and 42. Thus the amount of unremoved iollow-up-or the dis expanded or contracted due to pressure changes in thechamber ll. The chambers 14 and 4| 50 placement between the position of lever 38 at the end of the follow-up movement and the end are connected by a'duct 43 in which is located a variable restriction 44 that may be adjusted of the compensating movement may be varied to change the rate at which pressures in cham by varying the area of bellows 42. The less the hers I8 and 4| may equalize. area 01 bellows 42 the smaller the unremoved 'In the operation of the device, assuming an 55 follow-up will be. At this time, assuming that increase in the temperature of the furnace above‘ the decreased pressure in chamber II has caused its normal value, the Bourdon tube 8 will be sumcient closing of valve 4, that the tempera expanded to move lever I8 clockwise and, through ‘ture has returned to its normal value, equilibrium link 21, move‘the pen 24 outwardly along the of the apparatus with the bellows 48 and 42 at chart (not shown). This movement will ‘cause 60 substantially their normal lengths is obtained ' the lever 88 to be moved clockwise around its with a pressure in chamber l8 di?'erent from right end to lift the left end oi’ bell-crank 34 the pressure in that chamber at the commence ment of the operations just described. and move that lever clockwise so that pin 33 Provision is made to change the control point rwill raise the ?apper I! from the nozzle :9, against the bias or spring 48. This movement 65 of the instrument, or the normal value or the temperature in the furnace l by altering the of the ?apper will permit more air to escape original position of the ?apper l2 relative to from the chamber l4, lowering the pressure in the nozzle 38. This is accomplished by ad that chamber and on diaphragm 28. As a result lusting the right end of the lever 38 that is of the decreasein pressure on 28 the valve mem supported by a link 10 from one arm ‘ll oi’ an ber II will close the inlet to chamber l8 and index member 12 that is also pivoted at 28. The open the exhaust port 22 and reduce the pres sure in that chamber and line 23. A consequent pressure reduction will occur on diaphragm 0 so that the spring I will close the valve an amount index member is adapted to extend down in front of the chart to indicate thereon the value at which the instrument is set to maintain. In order to adjust the index 12 there is provided a 8,801,801 ing movement takes place. knob 13 having a crank arm'll thereon which is connected to the upper end of the index by a links". When the knob 13 is rotated the index - ‘l2 will‘be moved across the chart to the de sired point and at the same time link ‘II will be raised or lowered, as the case may be. to shift, the initial position of lever '30 and bell crank 34- to control ?apper l2. Thereafter the 3 By the use of the _ springs l1 and ll the etiect of the relative areas of the bellows ll and II is somewhat removed as the tendency for l! to return to its normal . length is more pronounced. In this embodiment. also, the speed of compensation is regulated by the adjustment oi the restriction M. which ad justment should bear a relation to the time lag of the process being controlled. In other words Bourdon tube‘ tends to maintain the ?apper in its initial position and the temperature 0! vthe 10 it may be said that. ordinarily the time required , for effecting thev automatic resetting or com furnace at the control point. pensating adjustment should increase or de The embodiment of the invention disclosed in Fig. 2 is essentially the same as-that of Fig. 1. ‘ crease in accordance with the rate at which change in the controlled process or operation but differs therefrom in certain constructional occur. 15 details whose purpose will be set forth below. In the above described embodiments of the In the form of the invention of Fig. 1 the nat invention the nozzle 30 has been shown in com ural resiliency of the bellows I! was used to re munication with the chamber II. This is not turn those'bellows to their normal length dur necessary and another manner in which pres ''ing the compensating movement as the pres sure in chamber I‘ may be adjusted is shown sures in chambers II and il equalized. At times 'in' Fig. 3. In that ?gure the nozzle 39A issup it is desirable to use some auxiliary force to plied directly with‘ air from the line it that return the bellows to their normal length. To also communicates with the diaphragm 20. this end the head to thafcloses the bell shaped casing in‘Fig. 2 is formed with an'inwardly ex-‘ ‘ Thus changes in pressure as a result oi- move tending cup-shaped portion II having an open 25 ment of flapper l2 relative to the nozzle "A only serve to move the valve member II to ad ing through its bottom wall. Fastened to the just the pressure in chamber Ii. Aspressure bottom wall of the part Si is one end of a bel changes in chamber II are applied to the con lows member 52 whose other end is attached to trol valve diaphragm through line 23, this same a plate Ill that has an opening therethrough. The open end of a bellows M is attached to 80 pressure is applied to the chamber l4 throng . a line “a connecting with line It. ‘ ' the other face of the plate I! while the closed The mechanism located in casing 31 in this end of the bellows is held in a given position figure may take the form of either Fig. 1 or Big. by its attachment to a U-shaped member 5! 2. In either case the~operation is the same as that straddles the bellows and is attached to described for that embodiment. the face of head 50. Because of the openings 35 above While in accordance with the provisions of in plate It and the bottom wall of the portion the statutes, I have illustrated and described the ii. the interior of bellows i2 and I‘ are in com best form of embodiment of my invention now munication with the interior of bellows 40 to known to me. it will be apparent to those skilled form a chamber 56 corresponding to the cham in the art that changes may be made in the ber ll of Fig. 1. form of the apparatus disclosed without depart Located within the bellows t2 and tending to ing from the spirit‘of my invention as set forth force that bellows toward a longer length by in the appended claims and that in some cases means of its engagement with portion II and certain features of my invention may be used to plate 83 is a spring '1. In a like manner a advantage without a corresponding use of other spring 58 is located in the bellows II to abut‘ features. ' against plate ti and oppose the spring 51. Be— Having now described my invention, what I cause of the springs 51 and 58 the plate It is claim as new and desire to secure by Letters ‘ at all times resiliently biased toward a 'given Patent. is: position. _ i. In an air control instrument the combina The connection between the bellows 40 and 50 tion of a cupsshaped casing. a bellows extending member 38 whereby movements of. that bellows into the same to form a chamber therein, a may move the ?apper valve l2 comprises a rod second bellows forming with the ?rst bellows and 59 that is attached to the bellows and the plate casing a second chamber. a re"tricted passage 81. This rod passes through the opening in~ portion 5i and the spring '1. A yoke member 55 way between said chambers, a supply of air and an exhaust nozzle for said first chamber. a nap Cll surrounds the bellows “and is attached to per valve for said nozzle. means responsive to the plate 53 for movement therewith. The the variations in the value of a condition to ad movement of yoke 80 is transferred to member just said valve relative to said nozzle to thereby 3! by means of a rod II. vary the pressure in said chamber, and means The operation of this embodiment of the in extending through the second bellows and at vention is essentially the same as that above de- . tached to said ilrst bellows operative upon move scribed in connection with Fig. 1. Upon move ment of said ?rst bellows in response to a pres ment of the flapper it away from nozzle to sure change in the first chamber to readjust the more air can escape therefrom to reduce the pressure in space It and cause an expansion of 65 valve in a reverse direction. 2. In an air control instrument, the combina— the bellows 48. Such expansion will shift bell tion or a cup-shaped casing. a bellows extend crank 34 to the right by means of the connec ing into said casing and attached at its open tions including rod I9, plate ‘I, yoke Oil and rod end- to the open end of said casing to form be II, and at the same time will compress the tween the two an expansibie chamber, a second spring 51. Upon a contraction of the bellows bellows fastened at its open end to the open end of - 4| the spring 58 would have been compressed said casing and in opposed relation to said ilrst by the plate 53. In either event the force of v bellows to form a second expansible chamber one of the springs 81 or 50 is added to the nat therebetween, a rod extending thorugh the end ural resiliency'of the bellows 48 in returning that of said second bellows and rigidly connected to bellows to its normal length as the compensat 4- '- ' 2,301,301 \ the ends of each bellows, a restricted connection between said two chambers, a supply of pressure ‘?uid for said ?rst chamber, an exhaust nozzle for said ?rst chamber, a valve cooperating with said nozzle to regualte the flow oi’ pressure ?uid therethrough, and means jointly actuated by vari ations in the value of a variable condition and by said rod to move said valve relative to said nozzle. ’ -' chamber, an exhaust port in said one chamber, an exhaust valve tor said port, means to Jointly move said exhaust valve comprising a part moved to a position proportional to the value 01' a condition and a part connected to said movable wall whereby upon movement or either part the a pressure in said one chamber and said controlled valve mechanism will be-varied, a restricted connection between said two chambers and means tending at all times to move said movable wall to a given normal position. . 3. In an air control instrument a cup-shaped casing open at one end, a bellows extending into said casing and attached to the same at said end to form between the casing andv bellows an . 6. An air control system comprising a con expansible chamber varying in size as the pres- -. sure in said chamber changes, a second bellows also attached to said casing at said end- and forming with the casing and ?rst bellows a sec- ' ond expansible chamber, a rigid connection be tween said two bellows’ and extending beyond the second one, a restricted connection between , ‘ said two chambers whereby a pressure change trolled valve' mechanism, and a control unit hav ing a closed casing and a movable wall therein forming a pair of chambers, means including a restriction for supplying air simultaneously to said controlled valve mechanism and one of said chambers, a supply 01' air passing through said restriction, an exhaust valve regulating the ex haust or air from said controlled valve mech anism and said one.chamber and thereforethe ' in one is slowly communicated to the other, a' source or ?uid under pressure communicating pressure in them,'means including means at valve in response to variations in the value of to cause the controlled valve mechanism‘ and said movable wall to assume positions corre tached to and actuated by said movable wall and with said ?rst chamber, a bleed nozzle for the ?rst chamber, a valve adapted 'to regulate the .' means movable in accordance with the value of bleed through said nozzle, means to adjust said - a condition for positioning said exhaust valve a variable condition to thereby change the pres sure in said ?rst chamber andthe length of said bellows and means operated by said rigid con nection to give a reverse movement to said valve. 4. In an air control instrument, the combina tion of a casing, a bellows extending into the same to form therewith an expansible chamber, a second bellows cooperating with said casing and ?rst bellows to form a second expansible cham ber, a variably restricted connection between said chambers, a source or pressure ?uid for said ?rst chamber, an exhaust nozzle for the ?rst chamber‘, a valve for said nozzle to variably .re strict the ?ow therethrough and thereby vary the pressure in said ?rst chamber and the length of said bellows,,means operative upon variations in a variable condition to move said valve rel ative to said nozzle to change the-pressure in the first chamber, and means rigidly connected to both bellows to move said valve in a reverse di rection in response to said pressure change. > 5. An air control system comprising a closed casing‘provided with a movable wall therein di viding the same into .a plurality of chambers whose size varies in accordance with the position of said wall, a controlled'valve mechanism, a connection between said‘ valve and one of said chambers whereby the pressure in the two is the same, a supply of air under regulated pressure for the controlled valve mechanism and said one sponding to the valueoi the condition, and means including a restriction i'orequalizing the pres~ sure on opposite sides of the movable wall to cause the controlled valve mechanism to be addi-e , tionally positioned with respect to the value of the condition. a ‘ Y' 7. Anair control system comprising a con trolled valve mechanism and a control unit hav ing a closed casing and a movable wall therein vforming a pair of chambers variable in size. means including a restrictionthrough which air is simultaneously- supplied to said control valve "mechanism and one of said chambers, a supply of air passing through said restriction, an ex haust port for‘said chamber and controlled valve mechanism, an exhaust valve regulating the ?ow oi’ air-through said port, means operated in re sponse to‘variations in the value of a ‘variable condition to adiust said valve and thereby change > the pressure in said one chamber and controlled valve mechanism, whereby said movable wall will be shifted, a mechanical connection, between said ‘ movable wall and exhaust valve operative upon movement of said wall to move ‘said exhaust valve, a restricted connection between said two chambers and meansat all times tending to move said movable wall to a normal position upon its displacement therefrom. ‘ ROBERT L. MALLORY.'