US2935077A - Bumpless manual automatic switch - Google Patents

Description

May 3, 1960 A. H. KEYsER BUMPLESS MANUAL AUTOMATIC SWITCH Filed vMarch 1. 1956 6 Sheets-Sheet 1 NAV IN1/Mm ALLEN H. KEYSER sy a S a `ATToRNr-:Y.

My 3, 1960 A. H. KEYsER BUMPLEss MANUAL. AUTOMATIC swITcH Filed March 1. 1956 6 Sheets-Sheet 2 All* l! INVENTOR. ALLEN H. KEYSER BY 2 s ATTORNEY.

May 3, 1960 A. H. KEYsER BUMPLESS MANUAL AUTOMATIC SWITCH 6 Sheets-Sheet 3 Filed March l, 1956 y mm .VNTL

INVENTOR. ALLEN H KEYSER BY p( ATTOR N EY.

A. H. KEYSER 6 Sheets-Sheet 4 May 3, 1960 BUMPLESS MANUAL AUTOMATIC SWITCH Filed March 1. 1956 ATTORNEY.

May 3, 1960 A. H. KEYSER BUMPLESS MANUAL AUTOMATIC SWITCH 6 Sheets-Sheet 5 Filed March l, 1956 INVENTOR ALLEN H. KEYSER BY Q /V ATTORNEY.

May 3, 1966 A. H. KEYsER BUMPLESS MANUAL AUTOMATIC SWITCH 6 Sheets-Sheet S Filed March 1, 1956 INVENTOR. ALLEN H. KEYSER 8% M ATTORNEY.

BUMPLESS `MAN UAL AUTOMATIC SWITC Application March 1, 1956, serial No. 568,782

s claims. (ci. rs1-sz) There are well known devices by means of which4 a valve, or the like, can be operated either manually, under the control of a human operator, or automatically, in

response to the deviations of some variable from a set;or selected value. These deviations are sensed by a measuring instrument which responds ,to changes in the chosen variable and converts such changes into variations in an air pressure. This variable air pressure is transmitted to a controller and thence to the air-operated motor for the valve. The manually operable means are similar and comprise, in Vtheir simplest form, a manually-operable valve for causing variations in an air pressure which is ap.- plied, either directly or after it has been amplified, to the air-operated motor forthe valve. It is likewise known to include in the-means for automatically operating the 'valve what is known as cascade control; In the cascade type of control, two controllers are employed, each responding to a different variable. One of Athese controllers is connected so asl to adjust the set point of the other controller.

'It is an object of this invention to provide means whereby the control of the valve may be transferred from the manual means to the automatic means or vice versa without disturbance of the position o-f thevalve at the 'time transfer is made. This is particularly advantageous if the valve constitutes the final control element of apparatus controlling an industrial process because changes in the position of such a valve cause changes in the industrial process. These changes cannot be quickly eliminated and consequently there is a disturbance of the process'under control and the resulting loss of efficiency. .More specifically, it'is an object of this invention. to provide a valve constituting the final control elementof an industrial process and having an air-pressure-operated motor for operating it; manually-actuated air-pressureoperatedmeans for `operating said motor and said valve; automatically-actuated air-pressure-operated means for operating said motor andsaidvvalve; a transfer valvefor taking the control of the valve away from the manu ally-actuated means and. givingv the control to the automatically-actuated means, or vice versa, in which the manually-actuated means includes: a transmitter-receiver having a first air-pressure-operated motor; a second airpressure-operated motor; valve arrangements for maintaining the air pressures in said motors equal; and'ahandie, or the like, constituting means for operating one of said'motors by hand.

The various features of novelty which characterize this invention are pointed out with particularity in the claims annexed to and forming a part ofy this specification. -For a better understanding of the invention, however, its advantages and specific objects obtained with its use, reference should be had to the acompanying drawings and descriptive matter in which is illustrated and described a preferred embodiment A0f the invention.

Iny the drawings: figs. 1-6 each is a block diagram or schematic show- 935,07? Patented May 3, 1950 ice ing of one modified circuit arrangement for actuating a final control element.

`In these drawings, the solid lines represent pipes or other connections for air under pressure. The dotted lines represent mechanical connections. The dot-anddash lines represent the casing or other container in which various individual units are mounted. In each of these figures the circuit is shown in the automatic position.

Fig. l shows a final control element, such as a valve, and a motor 2 for actuating this final control element. Motor 2 may well be a diaphragm attached to the stem or actuating member of the valve and adapted to be exposed on one faceto an air pressure and to be engaged, on the opposite face, by a spring.

The supply of air for actuating motor Y2 is controlled by means of a transfer valve 3. This transfer valve comprises the parts enclosed within the dot-and-dash lines 4. A movable, air-conducting conduit 5 is Vpivoted at 6 and is connected to a conduit 7 which communicates with motor 2. By means of a connection S, conduit S is connected to handle 9 which constitutes a manual actuator for the transfer valve. In automatic position, movable conduit 5 communicates with a stationary, air-conducting port 10 marked A to indicate that it communicates with conduit 5 when the device is in automatic position and is otherwise'closed. Transfer valve 4V also includes another, stationary, air-conducting port 11 which is marked M to indicate that it communicates with conduit 5 when the device is in the manual position and is otherwise closed.

The manually-actuated means for operating valve 1 also include a transmitter-receiver, generally indicated at 12, and comprising the parts enclosed within the dotand-dash line13. Transmitter-receiver 12 forms the subject vmatter of a United States patent filed April 20, 1955 by Harold E. Eller and Robert D; Schmitt, No. 2,763,278. Transmitter-receiver 12 comprsesa ltered air supply BALS. communicating through a restriction 14 with a rst motor comprising a hollow Bourdon tube 15 having a stationary end 16 and a perforated, movable end 17 forming a nozzle cooperating with a iiapper 18, or like valve, mounted on the `movable end 19 of a second motor comprised by a Bourdon tube 20 having a stationary end 21. A mechanical connection 22 is connected to Bourdon tube 20 and connects to a locking device 23. A second mechanical connection 24 connects to a handle 25, which forms the manual actuator for valve 1. The stationary end 16`of thefirst motor 15'is connected by-a conduit 26 to port 11. T he stationary end 21 of second'motor 20 is connected by conduit 27 to p ivot 6 and pipe 7.

The automatically-actuated means for operating valve 1 include a controller, generally indicated at 28. Controller 28 is of the stack type. Such stack type controllers are well known in the art. Examples are U.S. Patent 1,991,309 to D. HL Annin and U.S. Patent 2,518,244 to C. B. Moore. In general, such stack type controllers comprise a rigid casing 29 divided by flexible diaphragrns 30, 31, 32, and 33 into separate compartments or chambers each having a diaphragm as a movable wall thereof. The air pressure in chamber 34 opposes the air pressure in chamber 37. Chamber 34 is known as the positive feedback pressure chamber while chamber-37 is known as the negative feedback pressure chamber. An air pressure, which varies in response to the changes in the measured or process variable, is fed to chamber 36. This `air pressure is supplied by means of a measuring instrument, which responds tozchanges in the process variable to which the valve 1 is to respond. Thesechanges are measured by a measuring instrument, which VConverts the changes in the variable to changes in an air pressure and transmits them to chamber 36. Such measuring instruments and such means for convening Nassainir them into changes in air pressure are well known. Examples are to be found in U.S. Patents 2,216,448 and 2,311,853, both to C. B. Moore. Therefore, such a measuring instrument is not illustrated in detail herein save by the block 39, which is marked Automatic. Conduit 40 conducts the air pressure from the automaticallyactuated measuring instrument 39 to the process variable pressure chamber 36.

The pressure of air in chamber 35 opposes the pres-V sure of air in chamber 36. Air pressure is supplied to chamber 35 at a selected value by means of a. set point adjustment 41 and a conduit 42. Such a set point adjustment may constitute a manually-actuated, air-pressure regulator, which is well known in the art and which is not illustrated herein in detail.

If the pressure in chamber36 varies from the pressure in chamber 35, the output pressure of the controller in chamber 43, is varied and is transmitted by conduit 44 automatic position, pipe 44, conduit 5, and pivot 6 are connected to pipe 45 which conducts the air pressure applied to motor 2 to chamber 37 and, through restriction 46, to chamber 34. When the pressures in chambers 35 and 36 and in chambers 34 and 37 are equal, the controller 28 is in its balanced or normal position and the output pressure in chamber 43 and pipe 44 is at a selected ratio to the instantaneous value of the measure variable, as represented by the air pressure in set point pressure chamber 35. This is the condition of the controller 28 in the automatic position in which the device is shown in Fig. 1.

The operation of the device is as follows. In the automatic position Vshown in Fig. 1 any change in the process variable to which the measuring instrument 39 responds actuates the controller 28 and causes a variation in its output pressure. This output pressure passes through chamber 43 to pipe 44, conduit 5, pivot 6, and pipe 7 to the airzoperated motor 2 for the valve or final control element 1. This moves valve 1 to an adjusted position. Simultaneously, the output pressure from controller 28 is fed through pipe 45 to chamber 37 and through restriction 46 to chamber 34. When the pressures in chambers 34 and 37 equalize, the controller again resumes its balanced or normal position. Simultaneously, the output pressure of controller 28 is fed from chamber 43 through pipe 44, conduit 5, pivot 6, and pipe 27 to second motor 20. Any variation inthe pressure applied to second motor 20 causes its free end 19 to move. Consequently, fiapper 18 moves relative to nozzle 17 on the free end of the first motor 15. Any movement of apper 18 relative to nozzle 17 varies the pressure in first motor and, consequently, the pressure applied from the source F.A.S. through restriction 14 and pipe 26 to stationary port 11. The motor 15 causes the nozzle 17 to follow the flapper 18 and to maintain a constant distance between the flapper 18 and the nozzle 17.

' Therefore, the pressures in motors 20 and 15 are equal.

Since the pressures in motor 20 and 15 are equal, the pressure in port 11 is equal to the pressure in motor 2. Consequently, handle 9 can be actuated to cause mechanical connection 8 to shift conduit 5 outof engagement with port 10, which is closed as a result7 and into engagement with port 11, which is opened as a result. Since-the pressure presently applied to motor 2, when the device is still in automatic position, is equal to the pressure applied to motor 2, when the device is shifted into manual position.v this transfer of the control or governance of motor 2 and valve 1 can be made without changing the position of valve 1 and without disturbance to the process under the control of valve 1.

When the device is in manual position, the locking device 23 is unlocked. Handle 25 may then be operated by hand and causes second motor 20 to move reto the transfer valve 3. When the transfer valve 3 is in Kill gardless of the air pressure within it. Movement of the free end of second motor 20 causes flapper 18 to move relative to nozzle 17 and thereby varies the air air pressure within the first motor 15 is connected to its stationary end 16, pipe 26, port 11, conduit 5, pivot 6, pipe 27, and stationary end 21 to second motor 20. The pressure within motor 20 is therefore equalized with the pressure within motor 15 and any mechanical strain on the second motor 20 is`relieved.

While still`in manual position, in order to switch to automatic position, it is first necessary to adjust the set point adjustment 41 by hand so that the pressure in chamber 35 is equal to the pressure in chamber 36. Then, the handle 9 can be operated by hand to cause the transfer valve 3 to close the port 11 and to connect the port 10 to the motor 2. This can-be done immediately without any intermediate stops or manual adjustments.

Fig. 2 shows an air-operated circuit very similar to that disclosed in Fig. 1 with the addition of cascade operation. vThose elements of the vdevice of Fig. 2 which are the same as the elements of Fig. 1, have been given the same reference characters. Only the following differences are to be noted. Adjacent port 10 is marked the letter A, adjacent port 11 is marked the letter M and adjacent' port 47 are marked the letters CS and S. This will be explained hereinafter. Mechanical connection 8, which connects to the handle 9, which forms the manual actuator for the transfer valve 3, has a branch connection 88 which connects with al movable, air-conducting conduit 93 which, in the automatic position shown -in Fig. 2, engages stationary valve stop 89. A second controller, which may be in every respect like controller 28, is indicated at 90 and connects, by conduit 91, to the stationary, air-conditioning port 92 adjacent which the lettersV CA and CS are marked. Controller 90, when the device is connected in the cascade position, operates the set point adjustment 41 and consequentlyvaries the pressure in the set point pressure chamber 35 of controller 28.

The mode of operation of the device of Fig. 2 is as described in connection with Fig.V 1 with the following differences. If it is desired to switch from automatic position to cascade position, the handle 9 is operated so that the transfer valve 3 is actuated and conduit 5 is moved out of engagement with port 10, which is closed, and into engagement withstop 47. This is the cascade seal position denoted by the letters CS. In the cascade seal position, the pressure in motor 2 is locked in motor 2, in second motor 20, and in chambers 37 and 34. When handle 91s operated to move conduit 5` it moves movable conduit 93 by means of connection 88 at the same time. Conduit93 is moved out of engagement with stop S9,

with which it was engaged in the automatic position, as

indicated by the letter A, and into engagement with the stationary port 92, with which it engages in the cascade seal position, as indicatedby the letters CS. The controller 90 is then manually adjusted so that its output pressure is transmitted through pipe 91, port 92, conduit Y93, pipe 94, setpointadjustment 41, and pipe 42 to the set point pressure chamber 35. By means ofthe set point adjustment of second controller 90 (not shown), the pressure inset point chamber 35 can be adjusted to equal the pressure in the process variable pressure chamber 36. Handle 9 can then be Yoperated so as to leave conduit 93 in engagement with port 92 in thercascade automatic position, indicated by the letters CA. Simultaneously, conduits s moved by handle 9'and mechanical connection 8 from engagement with stop 47 and into engagement with `port 10, sonthat the output of controller 28 is' fed to motor 2. If it is desired to switch from automaticrposition from cascade automatic position, handle 9 is operated so that conduit 5 disengages from port 10 and engages with stop 47. Simultaneously, conduit 93 is disengaged from port 92 and engaged with stop S9. This is` the seal position, indicated by the letter S. Set point adjustment 41 isthen operated'so as to Iadjust the Ipressure in set 'pointchamber35 to equalfthepressure in the process ,variablerv pressure chamber ,36.V VHandle 9 can same elements have been given the same `referencechar- .acters. The difference is that a` second` transmitterreceiver100 is employed to adjust the set point of controller 28. This transmitter-receiver, generally indicated at 100 comprises the parts enclosed Within the dot-anddash line 113. `Transmitter-receiver 100 forms the :sub-

ject matter of ra United States patent filed April 20, 1955 l by Harold E. `Eller and RobertD. Schmitt, No. 2,763,- 278. `Transmitter-receiver 100 comprises a filteredV air Supply F.A.S communicating-througha restriction ,114 with a first motor comprising a hollow-Bourdon tube115 having av stationary end 116 and` aperforated, movable end Y117 forming a nozzle cooperating with a flapper 118, or like valve, mounted on the movable end `119 of a second motor comprised bya Bourdon 'tube 1Z0-having `a stationaryv end 121. A mechanical connection 122 is connected to Bourdon tube 120v and connects to a lock.- ing` device 123. A second,mechanicabconnection 124 onnectstoi a handle 125, which forms the manual actu; ator for transmitter-receiver 100. Thestationary end 116 of the first motorllS is connectedby a conduit 42 to set point pressure chamber-35. The stationary end 121 of second motor 120 is connected by conduit 95 to con- 'duit 40 which conducts'the airpressure Vfrom the automatically-actuated measuring instrument 39' to the process variable pressure chamber 36. d o l A The advantage of using V.this second, ,transmitter-.rey .Ceiver 100 to adjust the setf point of controller .p28 .is that,` since the ;secondmotor,120 of second transmitterreceiver 100 is connected by means of pipe-951m pipe 40, which forms the outputfrom the measuring instrument 39, the p'ressurein second motor 120is maintained equal to the pressure in process variable chamber 36.

i Thereforethe control or governance of the final control valve 1 can v-be 4transferred from manual to automatic or vice versa, ,without a-disturbance to the process underthe controlof valve 1.

Fig.v 4 shows an `apparatus by vmeans of .which valve 1 can -be actuated manually, automatically, or automatically by two controllersyin cascade. .This 'apparatus is the same as that of Fig; 2 `except that a novel .form of transmitter-receiver is used between -the r second controllerz90, which gives thecascade mode of operation, and the lfirst controller 28which is used to control the finalr control element 1 automatically. This second trans- 'miner-receiver is generally` indicated -at 200. A,It com.-

pr-ises Athe subiect matter `ori-a United States patentby Harold JE. Eller, No. 2,884,939, issued'May 5, 1959. In general, this controller comprises the-parts enclosed Witl1 in the dot-and-dash lines 20.15.' A filtered air supply v F.A.S. is connected to a relay, generally."indicatedl at-R,

and comprising a restriction202 leading to a nozzle 203. Nozzle 203 is connected through ay stationary wall 204 to a motor comprised by-a bellows205 whose free end carries a perforated, T-shaped, exhaust port206. A smaller, sealing bellows 207 surrounds'the stem or vertical leg of the exhaust port206 and Vconnects to a stationary casing 209. The lower end of the verticalv leg of exhaust 206engages a fiapper 210 pivoted at 211. The free end of flapper 210 bears against an inlet port 212 directly connected to source-FAS. y

`A stationary pivot 213 supports a beam 214. The output of relay R isv connected by means of pipe 215 with the stationary'end; of first motor 216 formed by a Bourdon tube. The free end offirstmotor 216 is connectedbyacspring 217` to. beam 214. A pipe-218 connectsathefoutput pipe 40to the .stationary end of a second motor 219 Vwhose"freeV end'is connected by means @essere of `a spring-220- to a beam 214. A; third motor 221is connected at its free end by means of aleaf spring222 to beam 214. Pipe 94 leads to the stationary end of .third motor 221 from movable conduit 93. Conduits 215 and 218'communicate with one side of a valve 223 which is` located between the `stationary, ends of iirst motorv216 and of second motor 219. Valve 223 is connected by a mechanical connection 288 to connection 88, which, in turn, connects the mechanical connection 8 so that it can be actuated by -handle 9, which forms the manual actuatorA for the transfer valve. The second motor 219 isy connected by--a mechanical connection 224 toa locking device 225 and to a handle 226 which provides meansjfor moving lsecond .motorv 219 when the locking device is disengaged. o

Fig. 4 shows the device in the automatic position. This device can be switched directly from Vmanual to automatic to cascade position ork vice versa.` VIt is not necessary to-vary any of the air pressures manually nor to match any air pressures by observing gauges to insure that the air pressures are equal. This `is due to the fact that the second motor'20- of transmitter-receiver 12 is always connected to motor 2 so that the pressurerin second `motor 20 is always-equal to the pressure'in motor 2 and,.consequently, conduit 5 can be switched out of engagement with port 10 and into engagement with port '11 without changing theV pressure appliedito motor 2.

sure in second motor 219 is always equal to the outputv pressure of relay R which `isfed to set point pressure chamber 35 by means of pipe 42. Therefore, the output of controller 28 is always equal to the instantaneous value measured by measuring instrument 39.

Fig. 5 vshows a device for actuating a final vcontrol valve-1 ,either manually or automatically. Inthisfdevice, the transmitter-receiver 12l is used, not onlyjto actuate valve 1 manually, but also to adjust the set point of controller 28 when the device is in automatic position. This permits the control or governance of valve 1 `tobe transferred directly from manual to automatic or .vice versa. Two intermediate stops are required in order to do this. However, it is not necessary to manually adjust any air pressures while in these stop or seal positions. When the device is in stop or seal position the motor 2 is disconnected from thecontroller 6 and from transmitter-receiver 12. Therefore, the motor 2 is not actuated either manually or automatically;

To secure these results, the transfer valve 3 is provided with astop 300 located intermediateport 10, which is open in the automatic position, as indicated by the letter A, andport .11, whichis open in the Vmanual position, as indicated by thefletter M. Theletters S1 and S2i-applied to the stop `300 indicate that conduit 5 engages with stop 300 injthe first and second seal positions.- vIn addition to transfer valve section 3,- a second trans-y fer valve section, lgenerally indicated at 301,- is employed. Transfer valvesection 301 `comprises the parts enclosed within the dot-and-dash` lines 302. This transfer valve section comprises a stationary port 303, which is open in automatic position, as is indicated by the letter A.

A movable 'valve conduit'304 ispivoted at 305 so that it can engage Awith port 303 or with a port 306 which-is open in the first seal position, as indicated by the letters S1 applied to it. A third port 307 isopen in the second sealpostion and in the manual position, as is indicated by the letters S2 and M applied to port 307. Port 303 is connected to set p oint pressure chamber 35 by conduit 308 and by conduit 312 with pipe 26. APort 306 is connected to pipe 40 by conduit 309. Port 307 is connectedto pipe 45 by conduit.310. Movable valve conduit 304 is connected at its pivot 305 with theV stationary end 21 of second motor 2 0 by -means.,;1f.conf` duit 311.

, The sequence of operations in transferring the control or governance of valve 1 from manual to automatic control is as follows- In the manual position, transmitter-receiver 12 is actuated by handle V25 Vsince locking device'23fis disengaged. Handle 25, my means of mechanical connectionsv24 and '22, moves second motor 20 regardless of the pressure existing within the second motor 20 and causes flapper 18 tomove relative to nozzle 17 and con-v sequently to vary the output pressure from source F.A.S. through restriction 14, pipe 26, port 11,V conduit 5, and pipe 7, to motor 2. The'air pressure in motor 2 is also applied through pipe 7, pivot 6, pipe 45, pipe 3101, port 307, conduit 304, pivot 305, pipe 311, and stationary end 21 to second motor 20. Theair pressure in second motor 20 is therefore equal to the air pressure in rst motor 15, Handle 9, which forms the manual actuator for transfer valve sections 3' and 301, is then actuated so that mechanical connection 8 moves Y'conduit 5 out Yof engagement with port 11, which is: closed, and into engagement with stop 300. However, conduit 304 is not moved out of engagement with port 307 but remains in engagement therewith, as is indicated by the letters S2 applied to port 307. The device is therefore in the second seal position in which the manually adjusted air pressure from port 11 is cut off from motor 2 but in which the air pressure in motor 2 is appliedA to second motor 20 of transmitter-receiver 12.

Handle 91is then actuated again but conduit Sis not moved out of engagement vwith stop 300. However, conduit 304 is moved out of engagement with port 307 and into engagement with port 306. This is the first seal position, as is indicated by the letters S1 applied to stop 300 and to port 306. In this first seal position the air pressure in motor 2 is still cut off from the transmitterreceiver 12 but the `second motor 20 of transmitterreceiver 12 is now connected to the measuring instrument 39 by means of pipe 40, pipe 309, port 306, conduit-304, pivot 305, and pipe 311. The air pressure in pipe 40 therefore actuates second motor 20 and causes flapper 18 to move relative to nozzle 17 so as to adjust the pressure in first motor 15 to equal the pressure in second motor 20. First motor 15 is connected from its stationary end 16 through pipe 26, pipe 312, port 303, and pipe 308, to set point chamber 35. Therefore, the pressure in set point chamber 35 is made to equal the pressure in process variable `chamber 36. This causes theoutput pressure of controller 28 inpipe 44 and portl 10 to equal the pressure locked in motor 2.

Handle 9 is moved once again.- This causes conduit to move out of engagement with stop 300 and into engagement with port which is opened,'so that theV output pressure of controller 28 is fed from pipe 44 to motor 2. Simultaneously, conduit 304 is moved out of engagement with port 306,V whichis closed, and into engagement with port 303, which is opened. This is the automatic position, as is indicated by the'letter A applied to the ports 10 and 303. In this automaticposition, the handle 25 forms the set point adjustment.. This is accomplished by disengaging the locking device l23 so that handle 25 can be moved manually so as to cause mechanical connections 24 and 22 to move second motor 20 and thereby vary the pressure in first motor 15. The pressure in first motor is transmitted from source F.A.S. through restriction 14, stationary end 16, pipe 26, pipe 312, port 303, and pipe 308 to the set point pressure chamber 3S so that the pressure in chamber 35 can be varied to indicate a desired value of the process variable which it is desired to be maintained. Simultaneously, the pressure'in first motor 15 is fed from port 303, conduit 304, pivot 305, pipe 311, and stationary end 21 to second motor 20. This relieves the mechanical stress in second motor due to the movement of handle 25 causing second motor 20 to assume a position other than that which second motor 20 would assume due to the air pressure within it and equalizes the air pressures in motors 20 and 15.

f cated at 400, comprises the parts enclosed within the'dot- Fig. 6 showsrmeans by which valve 1 may be actuated manually, automatically, or by two controllers in cascade. Inthis modification, a-single transmitter-receiver is used both to actuate the valve 1 manually, when the device is in manual position,`or to actuat'e the 4set pointof controller 28, when the device isl --iny automatic position'. These results are achieved by an Varrangement very similar to that lof Fig. 57but in which the transmitter-receiver has a-third motor in it. 1

In this device, the transmitter-receiver, generally indiand-dash lines 401. Afiltered air supply F.A.S. is connected through restriction 14 `to the stationary end 402 of thel first motor 403 formed of a Bourdon tube having a nozzle 404 at its free end cooperating with a fiapper 405 and connected by a spring 406 to a beam 407 mounted on a stationary pivot 408. A second motor 409 is formed of a Bourdon tube having a vstationary end 410'and a movable end connected by a spring 411 to beam 407. A third motor 412 is formed of a Bourdon tube having a stationary end 413 and a movable end connected by a spring 414 to beam 407.

In addition to the transfer valve sections 3 and 301, this device is provided with a transfer valve section 500 comprising the ,parts enclosed within the dot-and-dash lines 501. These parts consist of a movable valve conduit 502 pivoted op a stationary pivot 503; the stationary valve port S04-connected to atmosphere or vent; Iand a sta'- tionary valve port V505 connected by pipe 91 to a second controller 90 which cooperates with controller 28 to actuate yfinal control valve 1 in cascade.

By means of this device the control or governance of final control valve 1 can be switched directly from manual to automatic to cascade automatic or vice versa. Between these positions stops must be made but it is not necessary to manually vary any of the air pressures while in these stop or seal positions. Transmitter-receiver 400, when the deviceis in manual position, may be manually actuated to control the final control valve 1 and, when the device is in automatic or in cascade automatic position, may be manually actuated to supply the set point pressure to chamber 35.

The sequence of operations in transferring the governance or control of final control valve 1 from manual to automatic to cascade automatic'is as follows. VIn manual position, the handle 25v mayV be actuated by hand, since the locking device 23 is disengaged, so as to move second motor 409 by means of mechanical connections 24 and 22; Mechanical movement of second motor 409 causes beam 407 to rock about its pivot 408 and to move flapper 405 relative to nozzle 404 and thereby vary the pressure in pipe 26.V The pressure in pipe 26 is transmitted through port 11, conduit 5 and pipe 7 to motor 2. This pressure is also transmitted from motor 2 through pipe`7, pivot 6, pipe45, pipe 310, port 307, conduit 304, pivot 305, and piper311 to.second motor 409. This can be accomplished kbecause the parts are inthe manual position indicated by the letter M appliedto ports 11, y307, and 504. Y Handle 9, which forms the manual actuator for the transfer valve sections 3, 301, and 500, can then be moved Y by hand. Conduit 5 is moved out of engagement with port 11, which is closed, andV into engagement with stop 300. Conduit 304 is not moved out of engagement with port 3 07. Conduit 502 remains in engagement with port 504. This is the second seal position indicated by the legend S2 applied to stop 300 and to ports 307 and 504. In this second seal position, the pressure in motor 2 is disconnected from port 11 and is locked in motor 2 and in chambers 34 and 37 and in second motor 409.

Handle 9 may then be moved. Conduit 5 remains in engagement with stop 300. Conduit 304 is moved out of engagement with port 307, which is closed, and into engagement with port 306, which is opened. Conduit 502 remains in engagement with port 504. This is the first seal position indicated by the legend S1 applied to stop 300`and. tor ports 306v and 504. In'thefrst 'seal position, theairv pressure is still locked in motor 2, the second motor 409 is disconnected from the pressure locked in motor 2 and is connected by means of stationary end 410, pipe 311, -pivot 305, conduit 304, port 306, pipe 309, and pipe 40 with process variable pressure chamber 300i controller 28. The pressure in second motor- 409 is therefore, governed by the measuring instrument 39. Second motor 409 actuates beam 407 and moves iiapper 405 relative to nozzle 404 and-thus causes the pressure in first motor 403 to become equal to the pressure set up by the measuring instrument 39 because the pressure in first motor 403 is equal to the pressure in second motor 409. The first motor 403 is connected by means of its stationary end 402, pipe 26, pipe 312, stationary port 303, and pipe 308 L with. the set point pressure chamber 34 off contrauer-28. The pressure in chamber 35 is therefore made to..equalthe pressure in chamber 36. This placesthe ontroller 28 in its normal` or balanced position so' that themotor2 may be connected to the output pressure `from controller 28 by means of pipe 44 and port 10 without movement of final control valve 1 and the consequent disturbance to the process under the control of valve 1. lHandle 9 is next caused to move conduit 5 away from stop 300'and into engagement with port 10, which is opened. Conduit 304 is moved out of engagement with port-306, whichr is closed, and into engagement with port 303, which is opened. Conduit 502 remains in engagement with port 504. In this automatic position, indicated bythe letter A applied to ports 10, 303, and 504, the handle 25 may be actuated so as to cause the transmitterreceiver 400 to vary the pressure in set point pressure chamber 35. The pressure n chamber 35 is also fed back tosecondmotor 409 so that the pressure in first motor 403 is equal to thepressure in second motor 409.

c Inorder toY switch from automatic position to cascade automatic position, it is first necessary to actuate'handle 9 so'that the parts assume the first seal position indicated bythe legend S1 applied to stop 300, to port 306, Yand toport 504.

Handle 9 can thenV be actuated so that the device assumes the cascade seal position designated by the legend CS applied to the stop 300 and to the ports 306 and 505.

In this cascade seal position, the output pressure from theV second controller 90 is applied through pipe 91, port 505, conduit 502, pivot 503, and pipe 506 to the stationary end 413 ofthe third motor 412. In this cascade seal position,gthird motor 412 actuates beam 407 inresponse to thef'output'pressure of the second controller '90 and therebyV causes the pressure in firstY motor 403 to be governed by the second controller 90. The pressure in motor 403 is transmitted from source F.A.S. through its stationary end 404, pipe 26, pipe 312, port 303, and pipe 308 to the set point pressure chamber'35 of controller 28. Therefore, the pressure in set point pressure chamber 35 isgoverned bythe second controller 90. Therefore, the output pressure of the first controller 28 is equalized with the pressure locked in the motor 2.

Handle 9 may then be actuated so as to move conduit S- out of engagement with stop 300 and'into engagement with stationary port 10. Conduit 300 is simultaneously moved out of engagement with port 306 and into engagementv with port 303. Conduit 502 remains in engagement with port 505.

In transferring the governance or control of the final control valve 1 from cascade automatic to automatic to manual, the handle 9 is actuated so as to operate the transfer valve sections 3, 301, and 500 in the opposite sequence.

While, in accordance with the provisions of the statutes, I'. have illustrated'and described the bestform of the invention now known to me, it will be apparent to those skilled 'in the art that changes may be made in theV form yffthe apparatus disclosed without'departing from the `spirit of the invention as set forth in the appended claims,

10 and that in some cases certain features of rthe invention may sometimes beused to advantagewithout a corresponding use of `other features.

,Having now described `my invention what I lclaim as new and desire to secure by Letters Patent is-as follows:

1. In an air-pressure-operated'mechanism for operating a final control element, means for shifting automatically between automatic-actuation and manual actuation and cascade-automatic actuation without disturbing the pressure of the air being impressed on the final control element at the time of the shift, said means including, a firstair-pressure-operated controller having a set point chamber therein responsive to a set point pressure representing that value of the process variable which it is desired that said controller maintain, an automatically or manually actuated transmitter-receiver, a first air-pressure-,operated motor in said transmitter-receiver and adapted for-connection to a supply of air under pressure, a second air-pressure-operated motor in said transmitter-receiver and connected to the final control element, valve means connected between and actuated upon relative movement of said first and second. motors so as to vary the pressure of the air being impressed on said first motor in such a sense as to cause said first motor to follow the movements of said second motor, a manually or automatically actuated set point adjustment means connected to said set point pressure chamber, and transfer valve means having a first part connected to the air pressure being impressed on the final control element and operable to connect said pressure to the output pressure from said controller or to said first motor and having a second part connected to the air pressure being impressed on said set point adjustment means and operable to connect said pressure to a cascade controller whose output pressure represents a second process variable and is to be connected so as to actuate the set point chamber of said first controller and thereby actuate the final control elementwith the cascade mode of operation or to disconnect said set point adjustment means from said cascade controller.

2. In an air-pressure-operated automatically or manually actuated mechanism for operating a final control element, means for shifting automatically between automatic actuation and manual actuation without disturbing the Vpressure of the air being impressed on the final control element at the time of the shift, said means including, a first air-pressure-operated controller having a set point chamber therein responsive to a set point pressure representingthat value of the process variable which it is desired that said controller maintain, a first automatically or manually actuated transmitter-receiver, a first air-pressure-operated motor in said transmitter-receiver adapted for connection to a supply of air under pressure, a second air-pressure-operated motor in said transmitter-receiver and connected to the nal control element, valve means connected between and actuated upon relative movement of said first and second motors so as to vary the pressure of the air being impressed on said first motor in such a sense as to cause said first motor to follow the movements of said second motor, transfer Vvalve means having a first part connected to the air pressure being impressed on the final control element and operable to connect said pressure to the output pressure from said controller or to said first motor, and a second transv mitter-receiver providing set point adjustment means, a first air-pressure-operated motor in said second transmitter-receiver adapted for connection to a supply of air under pressure and to the set point chamber of said controller, a second air-pressure-operated motor in said second transmitter-receiver and connected to means for automatically actuating said controller, and valve means connected between and actuated upon relative movement of said first and second motors so as to vary the pressure of the air being impressed on said first motor of said second transmitter-receiver and on said set point chamber of said controller in such a sense as to cause said first motor to follow the movements of said second motor.

3. In an air-pressure-operated mechanism for operating a final control element, means for shifting automatically between manual actuation and automatic actuation and cascade automatic actuation without disturbing the pressure of the air being impressed on the final control element at the time of the shift, said means including, a first air-pressure-operated controller having a set point chamber therein responsive to a set point pressure representing that value of the process variable which it is desired that said controller maintain, a first automatically or manually actuated transmitter-receiver, a first air-pressure-operated motor in said transmitter-receiver and adapted from connection to a supply of air under pressure, a second air-pressure-operated motor in said transmitter-receiver and connected to the final control element, valve means connected between and actuated upon relative movement of said first and second motors so as to vary the pressure of the air being impressed on saidV first motor in such a sense as to cause said first motor to follow the movements of said second motor, a second transmitter-receiver providing set point adjustment means, a firstv air-pressure-operated motor in sid second transmitter-receiver and adapted for connection to a supply of air under pressure and to the set point chamber of said first controller, a second air-pressure-operated motor in said second transmitter-receiver and connected to means for automatically actuating said first controller, a third air-pressure-operated motor in said second transmitterreceiver', a' cascade controller whose output pressure represents a second process variable and is to be connected so as to vary the air pressure in said set point chamber of said first controller-and thereby actuate said final control element with the'cascade mode of operationfand transfer valve means having a rst part connected to the air pressurev being impressed on the final control element and operable to connect said pressure to the output pressure from said first controller or to said first motor in said first transmitter-receiver and a 'second part connected to said third motor in said second transmitter-receiver and operable to connect said'third motor to the output pressure from said cascade controller or to vent said third motor to atmosphere.

4. In an air-pressure-operated mechanism for operating a final control element, means for shifting automatically between automatic actuation and manual actuationwithout disturbing the pressure of the air being impressed on the final control element at the time of the shift, said means including, an air-pressure-operated controller having a set point chamber therein responsive to a set point pressure representing that value of the process variable which it is desired that said controller maintain and having a process variable chamber therein responsive to a process variable pressure representing the instantaneous value of the process variable as sensed by a measuring instrument, an automatically or manually actuated transmitter-receiver, a first air-pressure-operated motor in said transmitter-receiver and adapted for connection to a supply of air under pressure, a second air-pressure-operated motor in said transmitter-receiver, valve means connected between and'actuated upon relative movement of said first and second motors so as to vary the pressure of the air being impressed on said second motor in such a sense as to cause said first motor to follow the movements of said second motor, an automatically actuated measuring instrument connected to said process variable chamber, and a transfer valve means having a first part connected to the air pressure being impressed on the finalcontrol element and operable to connect said pressure to the output pressure from said controller or to said first motor or to an intermediate seal position between said connected positions and having a second part connected to said second motor and operable to connect said second motor to said final control element or to said process variable chainber ofsaid controller or to said set point chamber of said controller, whereby said transmitter-receiver may be'- manually operated to adjust the final control element in manual position or to adjust the set point pressure in said set point chamber in automatic position or may be automatically operated to adjust the pressure in said first motor in an intermediate seal position. 5. In an air-pressure-operated mechanism for operating a final control element, means for shifting automatically between manual actuation and automatic actuation and cascade automatic actuation without disturbing the pressure of the air being impressed upon the final control element at the time of the shift, said means including, a first air-pressure-operated controller having a set point chamber therein responsive to a set point pressure representing that value of the process variable which it is desired' that said controller maintain vand having a process variable chamber therein responsive to a process variable pressure representing the instantaneous value of the process variable as sensed by a measuring instrument, an automatically or manually actuated transmitter-receiver, a first air-pressure-operated motor` in said transmitter-receiver and adapted for connection to a supply of air under pressure, a second air-pressure-operated motor in said transmitter-receiver, a third air-pressure-operated motor in said transmitter-receiver, valve means connected with and ac-- tuated upon relative movement of said first and second and thirdvmotors so as to vary the pressure of the air being impressed on said first motor in such a sense as to cause saidV first motor to follow the resultant of the movements of said second and third motors, a cascade controller whose output pressure represents a second process variable and is to be connected so as to vary the air' pressure in said set point chamber of said controller and thereby actuate 'said final control element with the cascade `mode of operation, transfer valve means having a first part connected to the air pressure being impressed on the final control element and operable to connect said pressure to the output pressure from said first controller or to said first motor in said transmitter-receiver or to lock the air pressure being impressed on the final control element therein when saidnfirst part is in a position intermediate said connected positions and having asecond part connected to said second motor in said transmitter-receiver and operable to connect said second motor to said final control element or to said process variable` chamber of said first controller or to said set point chamber of said first controller and having a third part con# nected to said third motor in said transmitter-receiver and operable to connect said third motor to the output pressure from said cascade controller or to vent said third motor to atmosphere.

6. In an air-pressure-operated automatically or manu-- ally actuated mechanism for operating a final control element, means for shifting between automatic and manual` actuation and vice versa without disturbing the pressure of the air being impressed on the final'control element at the time of shift, said means including, automatically actuated mechanism comprising a measuring instrument having an output air pressure representing the instantaneous value of the process variable and an air-pressureoperated controller having a process variable chamber and at least one feedback chamber in it, said process variable chamber being responsive to the output air pressure from said measuring element and said feedback chamber being responsive to the output air pressure being impressed on the final control element, manually actuated mechanism comprising a first air-pressure-operated motor adapted for connection to a supply ofair under pressure and a second air-pressure-operated motorconnected to thcfinal control element when the mechanism is in manual position and a handle connected to said second motorv and manually operable to move said second motor and to override the pressure of the air within said second motor, valve means connected between and actuated upon` relative movement of said first and second motors so as to vary the pressure of the air being impressed on said first motor in such a sense as to cause said first motor to follow the movements of said second motor, and a transfer valve means connecting the nal control element to said first motor of said manually actuated mechanism or to said automatically actuated mechanism.

7. In an air-pressure-operated automatically ormanually actuated circuit for operating a final control element, means for shifting automatically between automatic or manual operation without disturbing the value of the air pressure being impressed on the final control element at the time of the shift, said means including, a controller having separate interacting pressure-responsive chambers therein, one of said chambers being a process variable chamber responsive to air at a pressure representing the instantaneous value of the process variable, another of said chambers being a set point chamber responsive to air at a pressure representing the value of the process variable which it is desired that said controller maintain, another of said chambers being a feed-back chamber, and another of said chambers providing the output pressure of a controller, a manually-operable transmitter-receiver, a first air-pressure-operated motor in said transmitter-re ceiver adapted for connection to a supply of air under pressure, a second air-pressure-operated motor in said transmitter-receiver, a handle engaging said second motor and manually operable to move said second motor, a valve having a first part connected to said rst motor and a second part connected to said second motor and operable so that relative movement between said first and second motors varies the value of the air pressure being impressed on said first motor from said source and causes said first motor to follow the movements of said second motor, and aV manually operable transfer valve having one part connected between the output pressure from said controller and a motor which actuates said final control element and adapted to open or close said connection and another part connected between said first motor and said second motor of said transmitter-receiver and adapted to open or close said connection.

8. In an air-pressure-operated automatically or manually actuated circuit for operating a nal control element, means for shifting automatically between automatic or manual operation without disturbing the value of the air pressure being impressed on the linal control element at the time of the shift, said means including, a controller having separate interacting pressure-responsive chambers therein, one of said chambers being a process variable chamber responsive to air at a pressure representing the instantaneous value of the process variable, another of said chambers being a set point chamber responsive to air at a pressure representing the value of the process variable which it is desired that said controller maintain, another of said chambers being a feed-back chamber, and another of said chambers providing the output pressure of said controller, a manually-operable transmitter receiver, a first air-pressure-operated Bourdon tube in said transmitter-receiver adapted for connection to a supply of air under pressure, a second air-pressureoperated Bourdon tube in said transmitter-receiver, a handle engaging said second Bourdon tube and manually operable to move said second Bourdon tube, a valve having a first part connected to said irst Bourdon tube and a second part connected to said second Bourdon tube and operable so that relative movement between said irst and second Bourdon tubes varies the value of the air pressure being impressed on said -iirst Bourdon tube from said source and causes said first Bourdon tube to follow the movements of said second Bourdon tube, and a manually operable transfer valve having one part connected between the output pressure from said controller and motor which actuates said iinal control element and adapted to open or close said connection and another part connected between said first Bourdon tube and said second Bourdon tube of said transmitter-receiver and adapted to open or close said connection.

References Cited in the tile of this patent UNITED STATES PATENTS 2,588,799 Booth Mar. 11, 1952 2,638,117 Horn May 12, 1953 2,658,516 Luppold Nov. 10, 1953 2,712,321 Grogan July 5, 1955 2,729,222 Dickey Jan. 3, 1956 2,731,023 Panich Jan. 17, 1956 2,743,710 Shannon May 1, 1956 2,747,595 Dickey May 29, 1956 2,763,278 Eller Sept. 18, 1956 2,834,362 Gorrie May 13, 1958 2,851,047 Eller Sept. 9, 1958 2,863,470 McChesney et al. Dec. 9, 1958 2,884,939 Eller May 5, 1959

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