US2612902A

US2612902A - Apparatus for measurement and control

Info

Publication number: US2612902A
Authority: US
Inventors: Charles F Ward
Original assignee: Reconstruction Finance Corp
Current assignee: Reconstruction Finance Corp
Priority date: 1946-07-13
Filing date: 1946-07-13
Publication date: 1952-10-07
Anticipated expiration: 1969-10-07

Description

Oct. 7, 1952 c. F. WARD 2,612,902

APPARATUS FOR MEASUREMENT AND CONTROL Filed July 1:5, 1946 m /44 l /44 I54 IN VE N T0,?

CHA mas/T \A/Ako Zy 1 flf ATTO NEYS Patented Oct. 7, 1952 APPARATUS ro g umsunsmsnr AND TRO -. 1 Charles F. Ward, Narberth, -Pa., as'signor, by .1 1 6 ass gnments, t c n t uction Finance Corporation, Philadel of the Uni edfStates t a, a cor rati n Application July l3, 1946, Serial No. 683,296

This invention relates to methods and apps-- ratus for measurementand control purposes, and specifically to pneumatic apparatus especially designed for industrial control and measurement.-

Improv'ed pneumatic apparatus for measures ment and control purposes is'described in the application of Winfield B. Heinz, Serial Number 652,525, filed March 7, 1946, now abandoned. The present invention relates to transfer meansfa'pplicable to the apparatus of said Heinz application and illustrated therein, though of broader application, whereby the final control element can be actuated from the controller selectively either by manual or by automatic operation. While the process is under manual operation under the action of the transfer means all conditions Within the controller remain'in a continuous state of balance so thatwhenever the variable and the control point coincide it will be possible to transfer the actuation of the final control element from manual to automatic operation .without any change in the position of the final control element resulting because of the transfer. Transfer from automatic to manual operation is also accomplished Without changing of thefmal control element.

The broad object of the invention is the pro? vision of transfer means of the type just indicated.

-This.and other objects of the. invention par, ticularly relatingto details of construction'and operation will become apparent from the followins description read in conjunction with the acpact n ra ngin wh ch:

Figure l isaodiagram showi g the el ents of a prefer whe o o de ntrol r e bod ing the matters of the present invention;

Figure 2 is a diagram illustrating the connections effected by the transfer valve whenin its A casing 2 having an external connection at 3 to the pressure to be controlled is sealed to a :the. position lows downwardly.

l2 and lever 1,4 thebellows is connected to a bellows ii to provide a closed chamber between the casing and the bellows, so that the bellows l is acted upon externally by the pressure to be controlled. 'A spring 5 urges the headof the bel- Through a rod 6, lever 8, link pointer-22 which may be of recording type carrying a conventional ink reservoir and pen ar-' ranged to trace a curve on a driven chart as i111istrated in'said Heinz application. An arm 30. of the lever arrang m nt has pivoted torit a link 32 connected to the upper end of a spring 34 havns-a link onne onto a relay as h reafter described.

1 A lever 36 having a fixed pivot 38is provided with a cam-following :44 engageable in a scroll groove 46 in one side of a cam -plate 48 which is arranged to be rotatably adjustable through, manipulation of 'a suitable knob. A pointer 56 secured to the lever 36 moves relatively to the same chartscaleas the pointer 22.

p A scroll groove 58 in the side of the ,cam' plate 4.8 opposite the scroll groove .45 receives a "camfcllowing pin 60 carried-by a lever 62 pivoted at .64 and connected through a link 65 and a spring- 10 to a relay as hereafterdes'cribed.

p {The springs 34 and lo are link-connectedas in ic ed in th d es am o a er 14 c t t tm part of a relay enerall designated 12,}the lever 14 being provided with a fulcrum at 75. The relay includes a ham 3 havin a mo ab wall constituted by a slack diaphragm 30 of'rela tively large area. Beneath this diaphragm is a second chamber 82, the bottom of which is closed by a slack diaphragm 8 of relatively small area. Beneath the lever 14 is another chamber'fiili, the upper side of which is closed by a slack ,dia phragm 88 of relatively large area while above this diaphragm is a chamber Blithe top of which is closed by a slack diaphragm 92 of relatively small area. For simplicity of description there may be assumed that diaphragms and 8-8 have the same area and that the'diaphragms $4 and 92 have thesame area though, as will be evident hereafter, this need not necessarily be the case, if additional loading'ineans are incorporated in the'relay. All four diaphragms are connected mechanically to the lever 14 by a pin arrange 'ment indicated at 94.

By the term slack diaphragm" as used herein there is meant a diaphragm of flexible material which exerts negligible spring action in its dis placement.

{The r ht'hand end of the lever 1.4 constitutes a baffle lying between a pair of nozzles 9.6 and 98 and arranged to restrict the flows therefrom to provide resistances depending upon the bafiie positions.

To provide for rate action,

resistances

360 and 362 are joined in series to the line 3, resistance 362 opening to the atmosphere. To the junction of these resistances there runs the connection 364 through the resistance 366 to the capacitance 368.

The chambers 82 and 90 are joined to the ends of the resistance 365.

A removable and reversible plate I is provided with grooves I02 and I04 for connecting ports, extending through the base plate of the apparatus, in a pair of alternative arrangements. One of these arrangements is indicated in Figure 1. The nozzle 98 communicates with a port I06, while the nozzle 90 communicates with a port I06. A connection I I 0 joins the chamber 86 with a port II2. A connection H4 joins the chamber 80 with a port IIS.

Two ports H6 and E areconnected together and to one end of a pneumatic resistance I22. This resistance, and similar resistances hereafter described may be conveniently referred to as fixed with the understanding that this means mechanically unchanged during operation as contrasted with variable resistances also referred to hereafter. Actually analogy to a fixed electrical resistor is not-strictly existent "when a compressible fluid is used since the resistance value is to some extent dependent upon the pressure drop therethrough. However, for descriptive and most practical purposes such a resistor may be considered fixed even in the sense of maintenance of a fixed value of fluid resistance. Two ports I24 and I20 are connected together and to a line I28 connectedto a port I42. A port I30 is connected through a line I32 and a second line I34 to a chamber I36 constituting a pneumatic capacitance. The passage I 32 also connects with a reset vent valve I38 by which the passage may be connected alternatively either to the atmos phere or to one end of an adjustable resistance I40, the other end of which is connected to the line I28. A port I44 is connected to the end of the resistance adjacentto the valve I38. The reset vent valve I33 is of simple construction, consisting of no more than a screw provided with a valve element I39 movable between two seats, the valve stem being provided with a bore open to the atmosphere so that when the valve element is seated to close off the connection to resistance I40, the connection I32 is vented to the atmosphere, while when the atmospheric connection is cut off, as illustrated in Figure 1, connection between I32 and I40 is provided.

The ports I42 and I44 constitute apair of ports in a circular array the various ports of which are arranged to be selectively joined by a transfer I valve, the construction of which is hereafter described.

For the present, it may be pointed out that besides the ports I42 and I44 in the circular array, there are ports I46, I48, I50, I52 and I54. The transfer valve comprises grooves I56, I 58 and I60 for the selectiveinterconnection of these ports. In Figure 1 these grooves are indicated dotted in the positions assumed during automatic operation.

The port I46 is connected through the line I 62 with the end of the resistance I22 remote from the port H8 and to an automatic pressure regulating means I64 communicating through a line I 65 with a supply of air under pressure.

The port I48 is connected through the line I66 to a pressure gauge I68.

The port I is connected through a line I10 with a second automatic pressure regulating means I12 connected through a line I13 with the supply of compressed air.

The port I52 is'connected through a line I14 with the final control element, which in the pres- .ent instance is illustrated as a diaphragmoperated .valve I16 in a fluid line I18. As will be evident hereafter, the pressure delivery line I14 may be connected to any type of final control element. The ultimate function of the controller is'toprovide at every instant whatever particular pressure is required in the line I14 to control the process in such manner that the pressure in line 3 will-be maintained at a selected constant value.

As an example, the valve I16 might control the 1 flow of fuel through the line I18 while the pressure in line 3 may be a function of temperature or some other variable; or the pressure in line I14 may control an electric current, flow of a chemical reagent or the like, and the pressure in line 3 may respond to viscosity, liquid level, speed, or'somc other variable. The apparatus is capable of quite general application, the particular applications forming no part of the present invention.

The port I 54 is connected through the lines I 00 and I 82 to a gauge I84 and through the line I88 to a port I61'zcontrolled by the upper piston I88 of an amplifier. This piston has associated on the same stem with it a lower piston I92 to define a space in the piston-mounting cylinder to which air','under controlled pressure, is led through the linesI62 and I94. The pistons I88 and I02 are connected to a lever I96 having a fulcrum at I98 and acted upon by a spring 200, the force exerted by which is adjustable. In the amplifier, a chamber 202 has its upper side closed by a slack diaphragm 204 and is connected through a line 205 with the end of the resistance I22 which is joined'to the ports H8 and I20; Above the lever I96v is a chamber 208, the lower side of which is closed bya slack diaphragm 2 I0. This chamber 208 is connected through the line 201 to the junction of a pair of resistances 209 and H I, the latter being adjustable. These resistances are in series, with the free end of the resistance 200 connected to the line I86 and with the free end of the resistance 2II communicating with the atmosphere. A pin 2I2 connects both of the diaphragms 204 and 2I0 to the lever I96.

The details of the apparatus so far outlined will be understood from consideration of said Heinz application but need not be described herein since they form no part of the present invention.

The transfer valve cooperating with the ports I42, I44, I46 and I52 and I54 is merely a disc adjustable manually and provided with grooves I55, I58 and I60, the arrangement and dimensions of which are indicated in Figures 2, 3 and 4, these being arranged to join selectively various combinations of the ports. As will be indicated in the following description of the operation the transfer valve is adjustable to three positions for securing respectively manual and automatic operation and balancing.

The operation of the apparatus so far described will be'best understood by considering first the conditions which exist when the system is in equilibrium and arranged for automatic operation as indicated in Figure 1. Under these circumstances the measuring element 2 is subject to ment and its associated stylus 22 and chart scale. As will be evident hereafter the lever,

has only a very slight movement and-consequently' the stylus pen will mark on the chart a line, the position of which depends solely on the pressure in the line 3.

Under equilibrium conditions the pressures in the

chambers

18 and 88 are equal-since-these chambers are connected together-through the resistance I 46. Likewise the pressures in the chambers 82 and 96 are equal since, 011th? assumption of equilibrium, there is no flow through the resistance 366 and consequently nopressure drop across the same, the pressure in the chambers being that existing at the junction of. the resistances 360 and .362: bearin a fixed relationp o the difierence between rthe pressure in the line 3 and atmospheric pressure.

The pressure regulator I64 maintains substantially constant pressure at the right hand end of the resistance I22 and consequently, with the baffle lever '14 in fixed position a constant flow takes place through the nozzle 98 and themessure in the chambers 13 and 86 corresponds'to the pressure drop through the nozzle.

The constant nozzle pressure is applied through the line 266 to the chamber 262 of the amplifier and equilibrium in the amplifier is maintained by an assumption of the position of the valve 1488 which provides at the junction of the resistances 209 and 21! a pressure applied to the chamber 268 which maintains the lever I96 in fixed position. The pressure in the line 1186 being constant a constant pressure is applied to the valve 116' to maintain a constant flow through the line H8, or alternatively a constant condition of whatever responds to the pressure in the line lie.

In view of the equality of pressure in 'xthe chambers of each pair in the primary-relay it will be evident that equilibrium requires a balance of the torques exerted on the lever-ls byxthe springs 34 and H1. The tension of the springdll is fixed by the adjustment of the loam disc :48 and as will be evident, the pointer 56 occupies a position which is indicative of, and uniquelyrelated to, the tension of the spring 76. If an adjustment is effected to change the tension of the spring 10 and equilibrium is again attained it will be evident that the torques exerted by the springs .34 and 16 must again balance. Accordingly, whenever equilibrium is attained the pressure in the line 3 must bear a definite relationship to the tension of the spring 16. construction of the grooves in the cam 48, the arrangement of the levers, and the adjustments of the springs, the apparatus is so arrangedthat the pointer .56 and the stylus 22 must always be in coincident positions along the common chart scale when the apparatus is in equilibrium. There will now be discussed the operations by which equilibrium is attained following either anadjustment of the "tension of the spring Hi, i; e.; of

the set-point of the apparatus or a change in the pressure in the line "3. Since the actions are essentially similar it will be assumed that the adjustment of the set-point remains fixed and that a pressure rise occurs in the line 3. In order to simplify the description it will be first assumed that the

resistances

366, 362 and 356 and the capaci- By reason of the tance1368 are absent and thatcham ers 12 and 6.6 are either missin or, equivalentl are pen to t e atmosphere. As a matter of fact, if th aparatus operated without rate effect his will be the-case. irate .efiect beineuunnecessary in certain instances,

A rise in pressure in he line 3 will raise the link :32 and incr as the tension n the sprin 34. This'action :is a companie y a mo e of the stylus 2:2 away fr m the s t-p int so that the stylus immediately and continuously indicates the pressure in t e li h increase tension in the sprin :34 raises the baf l l v 0f the p imary re aypenin t n z i i e 9 beyond its previous position and so causing'a substantially immediate drop in the pressure in the chamber 86. this chamber having a low capacita e an being irectly c n ct d W t u s e tial'zi er c d es stance to th no zl If the connection from the chamber 18 was cut off entirely. it will be evident that equilibrium would be immediatelyattained due to the fact that the chambers .18 and 36 would .now'be at different pressures, this equilibrium involving a net zero torque on the lever 14 under-theactions of the tensions exerted by the springs .34 and 16 and the net force resulting fromthe difference in pressures between the chambers-1.8 and 8.6, the bafiie "lever '14 assuming such position relative to the nozzle 98 as .to-maintaina sumcient pressure difference to achieve equilibrium.

Actually, substantially-this does occur immediately upon increase in pressure in-the line 3 since due to the presence of the resistance 1.46 and the capacitance provided by chamber 136 the presu e in e chambe T rema ns mo e arily substantially constant. The reset action, :how-

ever, now begins. Since the pressure in the chamber 1.8 is greater than the-pressure in the chamber 86 a flow of air from the former to the latter must take place through the connection H4, port H6. passage I64 in bloc}; i-D,6,.port';i36, the body of valve 138 theresistance M6, port I24, passage I62 in block I00 and connection H6. Since capacitance I36, in effect, forms an enlargement of the chamber 18 the drop in pressure in 18 consequent to this flow takes place slowly to an extent de pendent upon the value of the resistance I46 and the size of the capacitance I36. As the pressure in the chamber 78 drops the downward force on .the lever 14 exerted by the diaphragm 86 is reduced .and consequently the nozzle 68 is still further opened to the extent necessary to produce a further drop in pressure in the chamber 86 to maintain mechanical equilibrium of the lever 74. The action accordingly is progressive: a step increase in pressure in the line 3 does not produce afixed pressure in thechamber 86 but causes an initial drop in this pressure followed by a continuing decreasein this pressure at a rate which is continuously proportional to the deviation of the pressure in line "3 from its control point, giving rise to aso-called proportional-speed floating action.

Ihe'nozzle pressure, 1. e., substantially the'pres sure the chamber 86, is applied to the amplifier illustrated at the lower left in Figure 1 and this amplifier delivers to the line 114 a pressure definitely related to the pressure in the line 266 in accordance with the principles set forth in Heinz application, Serial No. 561,073, filed October so, 1944, the pressureyin the line n4 constituting an amplification of the pressure'in the line 266.

The action of the pressure in the line Ht, by controlling a flow or some other action will tend to correct the deviation of thepressure'in the line 3 from the control point. As a consequence, the pressure in the line 3 will be caused to drop by the operation of the process with a resulting decrease in the tension of the-spring 34 so that ultimately there will again be attained mechanical equilibrium of the lever M when the pressures'lil and 86 are again equal so that the mechanical equilibrium of the lever 14 will depend solely on the balancing of the torques exerted by the springs 34 and 10,. Obviously this can only occur when the pressure in the line 3 again returns to the set-point since the sprin 10 has been unchanged. When equilibrium is again attained, however, the pressure existing in the chambers 18 and 86, while equal in the two chambers, will not-be the same as in the beginning. The baffle will be displaced slightly from its original position and the pressure above the nozzle 98 will have changed. As a consequence, the amplified pressure in the line H4 will also be different from, what is was initially, i. e., it may cause either a greater or less flow through the line H8 or a change in condition of some other controlled medium or controlled agent such as may be required under some new demands on the controlled system to maintain the pressure in line 3 at the set-point.

While What has just been discussed involved an actual change in position of the lever 14 it may be pointed out thatthe actual motion of the baffie end of this lever to secure a full range of change in the nozzle flow is, in fact, very small, being less than 0.001 inch. This movement is so slight as not to affect appreciablythe tensions of the

springs

34 and 70 so that for all practical purposes the lower ends of these springs may be regarded as occupying fixed positions through the entire range of the apparatus. The result is that the tensions of the springs effectively depend solely on the movements imparted by their upper ends with the result that throughout the entire range of operation substantially precise correspondence will exist between the set-point '6 and the recording stylus 22 when equilibrium is attained. 3

When rate efiect or action is introduced by the presence of the elements associated with the chambers 82 and 93 the action is rather similar but modified to the extent of some dependence upon the amplitude of the change in the pressure in line 3. Assume again that the pressure in line 3 increases. A proportional increase in pressure will appear at the junction of the

resistances

360 and 362 since their arrangement constitutes a pressure divider. It may be here noted the only reason there is provided a pressure divider is to reduce to some fraction of the pressure in line 3 the pressure which is introduced into the chambers 82 and 90, since in many instances the pressure in line 3 may be quite high and in excess of the pressure which the diaphragms in the primary relay can withstand without damage. So far as the action is concerned, the connection of the line 364 could be directly to the line 3 and, of course, such connection may be used if the pressure in the line 3 never exceeds a safe limit The increase in pressure in the line 364 will now cause a flow of air through the resistance 366 into the capacitance 368, the pressure in which, at the beginning of the change, will be that which prior to the change existed in the line 364. The resulting fiow through the resistance 366 will accordingly produce an immediate rise in the pressure in chamber82 as compared with the pressure in chamber 90. The result is that added to the upward force on the bafile which was caused by the tensioning of spring 34 there is a further upward force on the baffle resulting from the pressure difference between chambers 62 and 90, this pressure difference having the characteristics pointed out hereafter, it being suificient to state at the present time that, as will be evident, it depends upon the magnitude of the change in pressure in the line 3. The force so exerted upwardly on the baffle gradually decreases as the pressure in the capacitance 368 rises. Consequently, while it initially contributes to the drop in pressure in the chamber 86 its efiect becomes less with time. Final equilibrium, of course, involves equality of pressure in the chambers Biland 99 and no flow through the resistance 366.

The arrangement which has been described involving the control of the nozzle 98 results in a decrease in pressure in the line I'M when the pressure in the line 3 increases. It is desirable that the apparatus should be readily adjustable to produce an increase in the pressure in line I74 when the pressure in line 3 increases. This end is achieved merely by turning the plate I00 upside down whereupon connections are interchanged so that the nozzle 96 is rendered active, chamber 18 becomes the follow-up chamber and chamber 86 becomes the reset chamber, the capacitance I36 being connected directly to the chamber 86 rather than to the chamber 18. It may be noted that no reversal of the connections of the chambers 82 and 90 for rate action is necessary since these chambers are arranged to provide forces which are related always in the same fashion to the force exerted by the spring 34.

It will be evident that the various actions resulting from these changes or resulting from decrease rather than increase in pressure in the line 3, or resulting from a reset of the set-point are all essentially similar to those described above with mere changes in sign and it will, therefore, not be necessary to describe the various alternatives in detail. A lowerin of the set-point precisely corresponds to a rise in the input pressure and vice versa.

The rate action which has been described involves the introduction of an input differential pressure which is substantially proportional, under normal conditions, to the rate of change of the controlled variable or of some function of it represented by a fluid pressure. Since this rate action forms no part of the present invention it need not be described in detail and reference may be made to said Heinz application, Serial Number 652,525 for further description thereof. Reierence may also be made to this application for description of the steps involved in setting the parts of the apparatus and adjusting their actions.

It is important in a recorder-controller that means be provided whereby the final control element can be operated either automatically'by the controller itself or manually by the operator. The means provided for this purpose must be such that the operator can transfer from manual to automatic operation and, vice versa, without even a transient change in the pressure delivered to the final control element. In order that this be possible it is necessary that the operator be able to compare the pressure which fixes the position of the final control element with the pressure which will be applied to it on transferring from one regime to another. Before transferring it must be possible to adjust the new smattepressure to match exactly "the existing valve pressure in order that when the'transfer is effected therewill be no change in the position of the final control element and'thus no upset in the process conditions which are determined by its position. In the present apparatus these requirements are met through the action of the transfer valve diagrammed in the figures. I V

The automatic position of this valve is indicated in Figures 1 and 4 and its functions have been indicated in the description of the operation by the references to the various connections. In brief, the ports I42 and I44 are closed off by the valve disc so that the variable reset-resistance MI] is not short circuited. Ports I46 and I48 are connected so that the gauge I68 indicates the constant pressure which is. automatically maintained by the pressure regulator I64. v.Theport I50 communicates with the-groove 158 .but no connection is efiectedthereby so that the output of the regulator I12 is not fed tothesystem. Ports I52 and I54'are connected so'that the am' plifier output is delivered to the valve I 16..

If it is now desired to pass to manual operation the transfer valve is turned to a balancin position indicated in Figure 3. Ports I42 and M4 still remain closed and ports I52 and I54 remain connected so that the operation continues under automatic control. The change which is effected by-this position of the valve is merely to connect the gauge I68 to theYManlial. supply line I70 rather than to the. Automatic? supply line. Accordingly, it is now possible to compare In the position of Figure. 2 the ports I42 and IE4 are connected, short circuiting. the resetresistance I40 and quickly equalizing the pressures in chambers I8 andiifi. Port I46'comrnunicates with the groove I58 but no connection with any other part of the system is efie'cted'thereby.

The ports I48, I50 and. I52iarefionnected to gether. Accordingly, the gauge H58 continues to show the-output. pressure of the regulator 112 while, at the same time, through the port-I152 there is afforded a directconnection between the output of the regulator and 'theline I'M .to the valve I'K. Port I5fl ,is cutoff. I

The process is no'wsubject entirely to manual control through manipulation or the regulator I12. At the sametimahoweverfthe .automatic parts of the system continue to function, with the exception that the resistance I40 is short circuited so that the samepressures continuously exist in chambers I8 and- 86. Accordingly, the parts may be adjusted .or .dismantlecl for repairs or replacements and when. reassembl'ecithey will attain their normal opetatingconditions.

In the reverse transition from-manuallto' automatic operation, while maintainingth'etransfer' valve in the Manual position, the oontrolpoint is adjusted to secure-on the' gauge: l-8'4 areading' corresponding to that on the-gauge IE8; The fact that resistance lit'il is short circuite'd insures that no timedelay is involved to permit equalization of thepressures-i'n chambers-18 and 86. When equality of the gauge readings-is attained the transfer valve can be'moved directly through the Balancing position to the'Auto matic position and automatic operation will-be T0 resumed. It will be seen that thus a transition from manual to automatic operation may be 6f? iected without disturbing a proper condition which may havebe'eniattained by manual adjustment; that is, the automatic operation is causedto meet the manual adjustment, not the manual adjustment the particular condition which may have been assumed by the continuousiy operating automatic devices.

' It'inay be noted that the transition between Figures 3 and 4 is merely one which results in economy of gauges; 1.6;, if gauge Isa-was permanently connected to line I10, Figure 3 might well represent the valve position for normal auto mati operation and the setting of Figure 4 would be unnecessary. In such case, however, a separate gauge would be provided .to show the pressure delivered by regulator I64.

As will be evident from the foregoing, not even transient disturbances are produced during these transrersin the output line I'M;

It will be evident from the foregoing that the recorder-controller which has been described is of very general application to any type of system in which an output pressure can be made to rep? resent a variable which is to be controlled and control of the variable may beexecuted through a pressure delivered by the controller; In fact, ituwill beevident, that the input to the system need not necessarily be a fluidpre'ssure but could well be a force acting directly upon the baffle spring 3.4. It will accordingly-be understood that while reference has'been made to an input pressureof the system, thedescriptions above applied equally to a mechanical orelectrical input acting p n the baflle spring :34, 7

While for the sake of simplicity the descriptionhas been based upon the useot air, it willbe evident that fluids in general maybe used in the system and thatanv ases o her tha r may be utilized orevcn liquids wh desir d.- I h case-of liq i s; of course th variou ea ita ces take-the form of in which the rise of liquid level with or Without compression of gas serves toprovide the necessary pressure ghanges therein. It will, of cour se ,be evident that the input pressure line may carry liquid-instead of gas.

It will also be evident that by simple reversals oithe parts the-entire system may be vacuum rather than pressure operated, the necessary changes for accomplishing such results being indicatedin Heinz application, Serial No. 561,073.

.If .fluidginput is used, the apparatus may be re arded as one typeofreceiVer for reception of fluidpressure from a transmitter. Pneumatic transmitters for difierent variables may be constructedin accordance with theprinciples ole.- scribed in said; Heinzapplioation, Serial No. 561,073,- Heinz application, Serial No. 612,505, filed August 24;, 1 945 the patent to Arthur E. Increase. John c Wi i s an infi l Heinz, Ne. 2,462,697, issued February 22 me dthe patent to William Melas and Winfield B.

Heinz, 1N0. 2,475,630 issued July 12, 19451.

:What ;I claim and desir to pr t s b L tters Patentis: I

l. Inicombination, means automatically operating to providea variable fluidpressure in ,ac-

cordance with changes ofna variable, manually first mentioned variable fluidv pressure, .a second gauge. and valve means and (connections thereto,

7 said valve meanshaving three positions, in one:

of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure, in the second of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the third of which it provides connection between said responsive means, said manually adjustable means, and said second mentioned pressure gauge, so that said responsive means is subject to control by said manually adjustable means, and said second mentioned pressure gauge indicates the pressure applied to the responsive means.

2. In combination, means automaticallyoperating to provide a variable fluid pressure in accordance with changes of a variable, manually adjustable means for concurrently providing a second fluid pressure, meansresponsive to fluid pressure, a gauge continuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides direct fluid connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means, said manually adjustable means and said second mentioned pressure gauge, and cuts the connection between said automatically operating means and said responsive means so that said responsive means is subject to control by said manually adjustable means, and said second mentioned pressure gauge indicates the pressure applied to the responsive means.

3. In combination, means automatically operating to provide a variable fluid pressure in accordance with changes of 'a variable, manually adjustable means for concurrently providing a second fluid pressure, means responsive to fluid pressure, a gauge continuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, said valve means having three positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure, in the second of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the third of which it provides connection between said responsive means and said manually adjustable means, so that said responsive means is subject to control by said manually adjustable means.

4. In combination means automatically operating to provide a variable fluid pressure in ac-,

cordance with changes of a variable, manually adjustable means for concurrently providing a second fluid pressure, means responsive to fluid pressure, a gauge continuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to eifect automatic operation thereof by the first mentionel fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means and said manually adjustable means, so that said responsive means is subject to control by said manually adjustable means.

5. In combination, means automatically operating to provide a variable fluid pressure in accordance with changes of a variable, manually adjustable means for concurrently providing a second fluid pressure, means responsive to fluid pressure, a gauge continuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, said valve means having three positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure, in the second of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the third of which it provides connection between said responsive means and said manually adjustable means, so that said responsive means is subject to control by said manually adjustable means, the change of said valve means from its second to its third position leaving the operating connections of said automatically operating means in substantially the same operating condition as when said valve means was in its first position so that said automatically operating means continues to operate in accordance with changes of the variable irrespective of adjustments of said valve means.

6. In combination, means automatically operating to provide a variable fluid pressure in accordance with changes of a variable, manually adjustable means for concurrently providing a second fluid pressure, means responsive to fluid pressure, a gauge continuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the first mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means and said manually adjustable means, so that said responsive means is subject to control by said manually adjustable means, the change of said valve means from its first to itsfsecond position leavingthe operating connections of said automatically operating means in substantially the same operating condition as when said valve means wasinits first position so that said automatically operating means continues to operate in accordance with changes of the variable irrespective of adjustments of said valve means.

7. In combination,;means automatically operating to provide a variable fluid pressure in accordance with-changes of a variable in relation to a setpoint and including means for adjusting a set-point, manually adjustable means forces currently providing a second fluid pressure, means responsive to fluid pressure, a gauge continuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically op--' erating means and said responsive means to effect automatic operation thereof by the rust mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equal.- ized, and in the second of which it provides connection between said responsive means, said manually adjustable means, and said second mentioned pressure gauge, so that said respon' sive means is subject to control by said mam ually adjustable means, and said second mentioned pressure gauge indicates the pressure applied to the responsive means, said means for adjusting the set point enabling the operator to provide a, fluid pressure output from said automatically operating means equal to the pressure delivered by said manually adjustable means prior to a transition from manual to automatic operation. 1

8. In combination, means automatically operating to provide a variable fluid pressure in accordance with changes of a variable in relation to a set point and including means for adjusting a set point, manually adjustable means for concurrently providing a second fluid pressure, means responsive to fluid pressure, a gauge con-'- tinuously responsive to the first mentioned variable fluid pressure, a second gauge, and valve means and connections thereto, saidvalve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof by the flrst mentioned fluid pressure and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the sec nd of which it provides connection between said responsive means and said manually adjustable means, so that said responsive means is Subject to control by said manually adjustable means, said means for adjusting the set point enabling the operator to provide a fluid pressure output from said automatically operating means equal to the pressure delivered by said manually adjustable means prior to a transition from manual to automatic operation.

F}. In combination, means automatically operating to provide avariable fluid pressure in ac cordance'with changes of a variable in relation to a'set point'and including means for adiusting 1 1 4 asetpoint, manuany adjustable means for concurrently providing a secondfluid pressure, means responsive togfluid pressure, a gauge continuously responsive'to the first mentioned variable fluid pressure; a second gauge, andvalve means and connectionstheretdlsaid .valve means having'two positions, in one for-which it provides I connection between said automatically operating means and said responsive means to effect automatic operation thereofby the first mentioned fluid J pressure and. provides connection between the "second mentioned pressure gauge and-said manually adjustable means so that by manual adjustment of the latter the pressurelindications of said gauges may be equalized, and in the secend of which it provides connection'between said responsive means and said manually adjustable means, so that. said responsive means is subject to control by said manually adjustable means, the changeof said valve means from its first to its second position leaving the operating connections of said automatically operating means in substantially the same operating condition as when said valve means was inits first position so that said automatically operatingmeans continues to operate in accordance with changes of the variable irrespective of adjustments of said valve, means, said means for adjusting the set point enabling the operator to provide a fluid pressureoutput from said automatically operating means equal to the pressure delivered by said manually adjustable means prior to a transition from manual to automatic operationi l0 In combination, means automatically operating to provide a fluidpressurein accordance with, changes of a variable, said automatically e operating means including a pair'of chambers joined by a fluid resistance to give reset action,

manually adjustable means for providing a second fluid pressure, means responsive to fluid pressure, a gauge responsive to the first mentioned fluid pressures, second gauge, andvalve means and connectionsthereto, said valve means having two positions, in one of which it provides connection between said automatically operating ,means and said responsive means to'effect automatic operation thereof. and provides connection, between thesecond mentioned pressure gauge and said manually adjustable means .sov

said manually adjustable means, and said second mentioned pressure gauge indicates the pressure applied to the responsive means, and at'the same time effects short-circuiting of said fluid resistance so as to maintain equalized the pressures in said chambers.

11 In combination, means automatically operating to provide a'fluid pressure in accordance with changes of avarlable, said automatically operating means including a pair of chambers joined by a fluid resistance to give re'set action, manually adjustable means for providing a second fluid pressure, means responsive to fluid pressure, a gauge responsive to the first-mentioned fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positionsjnone of Whichit provides connection between said-automatically operating means and said responsive means to efiect automatic operation thereof and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means and said manually adjustable means, and closes connection to said automatically operating means, so that said responsive means is subject to control by said manually adjustable means, and at the same time efiects short-circuiting of said fluid resistance so as to maintain equalized the pressures in said chambers.

12. In combination, means automatically operating to provide a fluid pressure in accordance with changes of a variable, said automatically operating means including a pair of chambers joined by a fluid resistance-to give reset action, manually adjustable means for providing a second fluid pressure, means responsive to fluid pressure, a gauge responsive to the first mentioned fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized-and in the second of which it provides connection between said responsive means and'said manually adjustable means, and closes connection to said automatically operating means, so that said responsive means is subject to control by said manually adjustable means, and at the same time effects short-circuiting of said fluid resistance so as to maintain equalized the pressures in said chambers, the change of said valve means from its first to its second position leaving the operating connections of said automatically operating means in substantially the same operating condition aswhen said valve means was in its first position so that said automatically operating means continues to operate in accordance with changes of the variable irrespective of adjustments of said valve means.

13. In combination, means automatically operating to provide a fluid pressure in accordance with changes of a variable in relation to a set point and including means for adjusting a set point, said automatically operating means including a pair of chambers joined by a fluid resistance to give reset action, manually adjustable means for providing a second fluid pressure, means responsive to fluid pressure, a gauge responsive to the first mentioned fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to eiiect automatic operation thereof and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means, said manually adjustable means, and said second mentioned pressure gauge, and closes connection to said automatically operating means, so that said responsive means is subject to control by said manually adjustable means, and said second mentioned pressure gauge indicates the pressure applied to the responsive means, and at the same time eflects short-circuiting of said fluid resistance so as to maintain equalized the pressures in said chambers,said means for adjusting the set point enabling the operator to provide a fluid pressure output from said automatically operating means equal to the pressure delivered by said manually adjustable means prior .to a transition from manual to automatic operation.

14. In combination, means automatically operating to provide a fluid pressure in accordance with changes of a variable in relation to a set point and including means for adjusting a set point, said automatically operating means including a pair of chambers joined by a fluid resistance to give reset action, manually adjustable means for providing a second fluid pressure, means responsive to fluid pressure, a gauge responsive to the first mentioned fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof and provides connection between the second mentioned pressure gauge and said menually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means and said manually adjustable means, and closes connection to said automatically operating means, so that said responsive means is subject to control by said manually adjustable means, and at the same time effects short-circuiting of said fluid resistance so as to mainta equalized the pressures in said chambers, said means for adjusting the set point enabling the operator to provide a fluid pressure output from said automatically operating means equal to the pressure delivered by said manually adjustable means prior to a transition from manual to automatic operations.

15. In combination, means automatically operating to provide a fluid pressure in accordance with changes of a variable in relation to a set point and including means for adjusting a set point, said automatically operating means including a pair of chambers joined by a fluid resistance to give reset action, manually adjustable means for providing a second fluid pressure, means responsive to fluid pressure, a gauge responsive to the first mentioned fluid pressure, a second gauge, and valve means and connections thereto, said valve means having two positions, in one of which it provides connection between said automatically operating means and said responsive means to effect automatic operation thereof and provides connection between the second mentioned pressure gauge and said manually adjustable means so that by manual adjustment of the latter the pressure indications of said gauges may be equalized, and in the second of which it provides connection between said responsive means and said manually adjustable means, and closes connection to said automatically operating means, so that said responsive means is subject to control by said manually adjustable means, and at the same time effects short-circuiting of said fluid resistance So as to maintain equalized the pressures in said chambers, the change of said-valve means from its 17 v first to its second position leaving the operating connections of said automatically operating means in substantially the same operating condition as when said valve means was in its first position so that said automatically operating means continues to operate in accordance with changes of the variable irrespective of adjustments of said valve means, said means for adjusting the set point enabling the operator to provide a fluid pressure output from said automatically operating means equal to the pressure delivered by said manually adjustable means prior to a transition from manual to automatic operation.

CHARLES F. WARD.

18 REFERENCES orrnn The followingreferences are of record in the file of this patent:

Number UNITED STATES- PATENTS Name Date Gorrie Nov. 9, 1937 Eckman Feb. 20, 1945 Mason July 12, 1949