US2284795A - Control mechanism - Google Patents

Description

June 2, 1942. N. BELAEF CONTROL MECHANISM Filed Feb. 23, 1940 INVENTOR. NIK OLAI BELAEF un N u a-k ATTORNEY.

Paienied June 2 1942 2,286,795, CONTROL MECHANISM Nikolai Belaef, Boston, Jam, assignor in Mason- Neilen Regulator Company, Boston, Maw, 21. voluntary association of Massachusetts Application February 23, 1940, Serial No. 320,330

12 Claims.

This invention relates to an improvement in control instruments of the kind used in connection with power operated valves or like devices to govern the value of a variable, and particularly concerns an improved means, adaptable to various kinds oi standard iasirumente, for maintaming a predetermined ratio between the value of a, controlled or dependent variable and that of another veritable; letter being indecendent or controlled from excernei source.

One cbieci invention to provide means which; be edvarrtegecuslgr either,

"so cenircl a dependent verieh'le in exact accordarise wiish the value an independent.

varlebie, er in once min were funciiorl cf the ci e 121 value, em change in value or .liene veriaioll. may desirably lee :3. linear en the in value of the independ value may vary inrelaiien care root or other lame r inomer e iooonizrc. corp-crater? strumenis iii 1c 'zicn ef which. may be inof standard innormal operam lie-ell "for the ere variable. oi'iier than a slight to enebie same mechae. reti e eonircller. While instruments have their pen or one of P alteration, e.

to oeriein inelicetir iliustraiee we of the ei; and while the corree eonding 31181 instruments have zelvoiel mints arranged in eireddied relon, as shewn my United States described is e "veil adapted for either kind of operating eeeemhiy.

It is e, for :51 eTejeei: ef chi; inventicn to provide e. ratio ecntrol mechanism which may beset e maintain the selected value difierentiel by the seine means ncrmelly used in the instrument for determining control setting of e. singie variable, the difference being indicated or recorded en lie usual scale of calibration.

in carrying; out the preferred mine of this invention, I have eucstiiuted for the usual operating connections between the ccnditien responsive elements, such as heliealcoils, and the power contreliing 1 ice, such as nozzle and flapper, e movement comprising four separate members having the general configuration oi e parallelogrem, namely. a fem-sided figure in which the opposite sides are always substantially parallel during all enereiing positions, and by combining.

en adjuseable cam with one or these members I vary the no" e-fiepper relation relatively to the coil movement to obtain the controi differential required. Eeceuse of the configuration of these The invention will be more fully understood,-

and further objects and advantages will appear from the following description taken in 00 tion with the accompanying drawing, in which: Fig. 1 is e. front elevation of a portion of an air' operated indicating pressure controller shew ing an operating and indicating mechanism em bodying my invention which is set ie mein'te" linear operating differential between ables as indicated en the scale oi ce ere Fig. 2 is a diagrammatic View cf pr mechanism illustrated in Fig. 1 slio'vim tion of the perm "when the -r ent pressure increases by an emoun'; irirllce the calibrated scale,

Fig. 3 is a view similar to $3 showing trolled pressure is increased ccrreeponcir Having reference to Fig. l of craw ing operating mechanism of an indieatilzg re'iie a sure controller is shown mounted. on e. .SlLlEi-LMG backing: plate 3 by which the essemlol may Ii conveniently attached to en instrument case not illustrated. The mechanism prcvlelerl with indicating pointers l8 and l 5 end in seeing indicator i2, herein shown as adapted to ccopereie with e pressure scale :13, it Eeeing understood that the pointers end scale be replaced by pen arms and chart if desired, and iurther mm the device is equally well e-dep'eed fer the conirol'ci temperature, level, rate of iicw or o'islier variable.

Al: M is an assembly support including circular portion i5 and an extension l3, circular portion being rotetaioly mounted on the Ecaclzing plate 9 by meene cf 2. fixed bearing ring and having a gear segment 38 meshing with a pinion 19, which is in tum mounted on 2; shaft 2%. The shalt 26 may be provided with e, squared end suitable for e. key, not shown, bywlrieh lhe assembly support arm may be rotated in a. deckwise or counter direction. The setting indicator i2 is aiiechecl to the circular portion 9% and serves to indicate the differential setting a manner to be described. The extension. 36 may carry a. nozzle 2i mounted on a, member 22 eeoured ho the extension. Cooperating with the nozzle 2i is e. flapper 23 secured at one end to a. cam follower arm 2-3 and pivcteily supported. at 25 lac the exienslcn l8. The free end of cam follower 25 is supported on e cam 33 lac be described. While 1 have herein shown one type nozzleflapper construction, it will Toe imelere aocd that any usual control mechanism may be employed.

A convenient operating fluid, for exem pie, air may be supplied under pressure to the nozzle El through a line 25 having a restricted orifice 2?. A pipe 28 may connect the nozzle line with a. meter valve 8, herein. shown in conventional manner as governing fluid flow through a line i to vary the value or a dependent variable, or the pipe 2% may connect with any other power operated. device suitable for governing any dependent variable, the value of which may be de -sirably controlled in some predetermined relation ly of four-members which are so arranged in respectto their relative positions and movements as substantially to constitute a parallelogram under all conditions of setting and control. These members comprise an arm 29-rigidly secured to a pivot shaft 30 to which the pointer H is also rigidly secured; an arm 3| rigidly connected to the pointer H! which isin turn mounted on a pivotal shaft 32, the shafts 30 and 32 being herein shown as arranged in straddled relation instead-of having a common center of rotation as is also usual; and a lever 33 and link 34, the lever being pivoted at one end to the free end of the arm 29 and at its other end being arranged to carry the cam 35, and the link being pivotally connected to the lever 33 and arm 3| as shown. The cam 35 may be adjustably secured to the le ver 33 by means of a frictional mounting such as a screw 36 or the like.

The pointers, l and il may be actuated by helical coils 31 and 38 respectively secured to the plate 9 by supports 8, the former coil being responsive to an independent variable, by means of a pipe 39, and the latter coil being sensitiveto a controlled variable which it is desired to mainaee aves V pendent variable is some multiple or sub-multiple of the value change of the independent vari able by swinging the cam about its mounting on arm 33. When the cam 35 is tilted in a counterclockwise direction about itspivot 36 the value of the dependent variable changes as a submnltiple' of the value change of the independent variable, and when the cam is tilted clockwise the opposite occurs; By changing the shape of the cam the value changes may be made to conform toa square root function or the like.

The operation of the device a as follows:

Having reference to Fig. 1, assuming that the value of the independent variable is twenty, as

shown by pointer in, and the dependent variable is to be maintained at a constant differential value of ten units higher, the assembly support i4 isrotated by the pinion I9 until the settingindicator |2 shows a unit differential of ten on the calibrated scale l3. The rotation of assembly plate M, for example, in a counter-cloclmise direction to move the setting indicator l2 from zero to ten on the calibrated scale l3, moves the nozzle 2| away from the flapper 23 reducing the nozzle pressure and by means of suitable control its fixed pivot 39 lowering lever 33 and cam 35' and moves the flapper toward the nozzle 2| to reduce gradually the rate of increase of the dependent variable and finally to check its increase entirely. When the pointer arrives at thirty on the scale the flapper-nozzle relation has been established to maintain the dependent variable at A thatvalue. Thus a standard instrument setting tain at a definite ratio value relatively to the independent variable by means of a pipe 40. The

free end of the coil 31 is adapted to rotate an arm 4|, pivoted on a shaft 42, at the center of'the coil and is arranged to move the arm in a coun terclockwise direction on an increase of magnitude of the independent variable. The pointer ill may be operativelyconnected to the arm 4| by a link 33, by which means the pointer is positioned on the calibrated scale l3 in accordance with the value of the independent variable. The

pointer may be in operative connection with the helical coil 38 by means of arm 44 and link 45 arranged in a similar manner to the connecting parts described. The coil 38, which is responsive to the magnitude of the dependent variable, positions the pointer |l over the calibrated the lever 33 and follower 24 that a change in value of the independent variable is followed by the same change in value of the dependent variable in order to maintain a constant differential between the two variables. The action may be varied so that the change in value of the demechanism, which is used for setting the control point of a single variable, may be used without any mechanical change for settingthe diiferential between two variables.

Having reference to Figs. 1, 2 and 3, if it is as sumed that the independent variable increases forty units in the course of operation, arm 4| will be rotated counter-clockwise by coil 31 and by means of link 43 will move pointer II from twenty to sixty. Arm 3| is thus rotated in a counter-clockwise direction around its ilxed pivot 32 and by means of link 34 turns lever 32 and cam 35 in the same direction about the pivotal connection of said lever with arm 23. Movement of cam 35 as described serves to raise follower 24 and consequently flapper 23 from the position shown in Fig. 1 to that shown in Fig, 2 thereby eflfecting an increase in the value of the dependent variable. Increase of value of the dependent variable will cause helical-coil 38 to unwind and rotate arm. 44 in a counter-clockwise direction.

Link 45 will thus move pointer H from its position at thirty on scale II, as shown in Fig. 1, to position seventy on the scaleas shown in Fig. 3. As'pointer approaches seventy the arm 23 is turned counterclockwise around fixed pivot 32,

and lever 33 and cam 35 are lowered to cause the ables. If the .independent variable decreases in value, the opposite occurs.

In general the operation'oithe ratio movement is such that the selected dlilferential is deterembodied in various forms.

, In the claims:

.1. A ratio control movement 'for connecting drlving'members and a driven member and ineluding in combination, a lever-f having a fixed pivot which is rotatable about its pivot in accordance with movement of one of said driving members, a floating lever pivotally mounted on said lever at a point apart from its fixed pivot, a second lever having a fixed pivot approximately at the pivotal mounting of said first lever which is rotatable about, its pivot in accordance with movement of another of ,said driving members, a link pivotally connected to said second lever and to said floating lever at points substantially equidistant from the pivotal mountings of each of said levers having an effective length substantially equal to the effective length of said first lever, and means operatively connecting said floating lever with said driven member, said means and said link and levers combining, when I the levers having fixed pivotalmountings are rotated in the same direction by said driving members, to effect movement of said driven member in one direction by one of said driving members and in the opposite direction by another of said driving members.

2. A ratio control movement for connecting driving membersand a driven member and including in combination, a lever having a fixed pivot which is rotatable about its pivot in accordance with movement of one of said driving members, a floating lever pivotally mounted on said lever at a point apart from its fixed pivot, a secnd lever having a fixed pivot approximately at thepivotal mounting of said first lever which is rotatable about its pivot in accordance with movement of another of said driving members, a link pivotally connected to said second lever and to said floating lever at points substantially'equidistant from the pivotal mountings of each of said levers having an efi'ective length substanequidistant from the pivotal mountings of each of, said levers having an effective length substantially'e'qual tothe efiectivelength of said first lever-,said, floating lever having a free end extending'jbeyond its pivotal connections, a cam mounted on'the ire'e endf ol said floating lever,

,said cam andsaid levers combining, when the levers mountedon fixed pivots are rotated in the 'samejdirection by said driving members, to effect movement of said driven member in one direction bygone ofsaidxdriving members and in another direction 'byanother of said driving members.

4.'A ratio control movement for connecting driving members and a driven member and including inQcombination, a lever having a fixed 1 pivot" which is rotatable about its pivot in accordance with movement of one of said driving members, a floating lever pivotally mounted on said lever at a point apart from its fixed pivot, a second'lever having a fixed pivot approximately at the pivotal mounting of said first lever which is rotatable about its pivot in accordance with movementoi another ofsaid driving members, a link pivotally connected to said second lever and to said floating lever at points substantially equidistantirom the pivotal mountings of each of said levers having an effective length substantially equal to "the effective length of said first lever, a cammounted on said floating lever, said cam and said link and levers combining, when the levels mounted in fixed pivots are rotated in the same direction by said driving members, to effect movement of said driven member in one direction by one of said driving members and in another direction by another of said driving members,

and means for tilting said cam in respect to said driven member to vary the ratio of movement imparted to said driven member by one driving memberln respectto the movement imparted by another driving member.

5;. A ratio control movement connecting driving members and a driven member and including in combination, a pair of angularly disposed members having fixed pivots each of which members is rotatable by a driving member, a second pair of "angularly disposed members pivotally mounted on said first pair of members and pivotally connected to each other substantially to form in conjunction with said first pair of members a tially equal to the effective length'of said first lever, a cam mounted onsaid floating lever in operative connection with said driven member, said cam and said link and levers combining, when the levers mounted on fixed pivots are rotated inthe'same direction by said driving members, to effect movement of said driven member in one direction by one of said drivingmembers and inanother direction, by another of said driving members. I I I 3. A ratio control" movement for connecting driving members and "a driven member and ineluding in combination, a lever having a fixed pivot which is rotatable about'its pivot in accordancewith movementof one of said driving members, a fioating lever pivotally mounted on said lever at a point apart from its fixed pivot, "a second lever having-a fixed pivot approximately at the pivotal mounting of said first leverwhich is rotatable about its pivot in accordance with movement of another of said driving members, a link pivotally connected to said second lever and to said floating lever at points substantially parallelogram, and means for operatively connecting one member of said second pair of members to said driven member, said means and said pairs of members combining, when the members of said first pair of members are rotated in the same direction by said driving members, to effect movement of said driven member in one direction byone of said driving members and in the opposite direction by another of said driving members 6. A ratio control movement connecting driving members and a driven member and including'incombination, a pair of angularly disposed members having fixed pivots each of which is rotatable by a driving member, a second pair of angularly disposed members pivotally mounted on said first pair of members and pivotally connected to each other substantially to form in combination with said-first pair of members a parallelogram, and'a cam for operatively connecting one member of said second pair of members to said driven member, said cam and said pairs of members combining, when the members of said first pair of members are rotatedin the same'direction by said driving members, to effect movement of said driven member in one directionby one of said driving members and in an

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