US1930353A - Proportional control apparatus - Google Patents

Description

Oct. 10, 1933. DOYLE 1,930,353

PROPORTIONAL CONTROL APPARATUS Filed June 11, 1928 Patented Oct. 10, 1933 UNITED STATES PATENT OFFICE- PROPORTIONAL CONTROL APPARATUS Application June 11, 1928. Serial No. 284,370

7 Claims.

My invention relates to control apparatus wherein the degree of control effected by said apparatus is proportional to the departure of the controlled condition from its predetermined or desired value.

My invention resides in circuit-controlling means in combination with control apparatus for intermittently closing a control circuit during a time interval which is proportional to the degree of departure of a deflecting member from a predetermined position.

My invention further resides in circuit-controlling means in combination with control and recording apparatus wherein an element of saidcircuit-controlling means is individually adjustable with respect to a predetermined control position of said apparatus for determining a different control position thereof.

My invention further resides in apparatus of the character hereinafter described and claimed.

For an illustration of one of the various forms my invention may take, reference is to be had to the accompanying drawing in which:

Fig. 1 is a view of my invention as applied to control apparatus.

Fig. 2 is a development of the circuit-controller shown in Fig. 1.

Fig. 3 shows diagrammatically an electric control circuit for co-operating with the control apparatus.

Referring to Fig. 1 control apparatus such as shown in U. S. Letters Patent to Leeds, 1,125,699, is shown associated with a circuit-controller embodying my invention.

The control apparatus comprises disengageable clutch mechanism for moving the main operating shaft 21 in either one direction or another in a manner hereinafter described. Galvanometer G, which is responsive to unbalanced conditions in an electric circuit, carries deflecting member 6 which moves with the galvanometer. Pivoted members '7 having extensions 7a substantially at right angles to said members, are adapted to be individually moved by the deflect ing member when it passes underneath either one or the other of the extensions 7a. Pivoted U-shaped member 8, having a cam operated actuating arm 9 engages deflecting member 6 in its upward movement, and, if the said mem her is underneath one of the extensions 7a, moves said member in a clock-wise or counter clockwise direction as the case may be.

Constant speed motor M through shaft land gearing 2 drives the main operating shaft 4 having mounted thereon cams 10 and 11 cooperating with arms 9 and 12 respectively. Arm

12 is pivoted near its upper portion and is normally biased in opposition to movement by its co-operating cam. Since shaft 4 operates at constant speed, arm 9 will be periodically cammed away from said shaft and member 8 moved upwardly about its pivots. Mounted on the lower extremity of member 12 is a pivoted element 13 carrying a transversely disposed clutch-engaging element 14, for engaging clutch disc 15 secured to shaft 21. Cams 16 are secured to shaft 4 and are adapted to engage one end or the other of the clutch engaging element when the same is in other than horizontal position.

It will be seen therefore that deflection of the galvanometer member from either side of its middle or neutral position results in movement of one of the arms '7, which engages pivoted member 13, thereby moving clutch-engaging member 14 from its horizontal position, whereupon one 76 of the cams 16 engages the end which is above the horizontal and restores it to its original position. During the above described operation of the clutch-engaging member, cam 11 engages arm 12 so as to raise member 14 away from 80 the clutch disc during movement of arm '71, but permits said member to be in engagement with clutch disc 15 directly afterwards and during actuation by cam 16.

The above mechanism therefore comprises a B5 disengageable clutch connection between main operating shaft 4 and control mechanism shaft H 21, depending as previously stated upon the position of thegalvanometer deflecting member 6.

Main operating shaft 4 is adapted to actuate through gearing 3 the counter shaft 5 which in turn through gearing 30 and 39 actuates a recording chart and circuit-controlling mechanism respectively. A recording chart is supported on a cylinder 29 carried by shaft 29a. Recording pen 28 carried by cord or flexible connection 26 around rollers 2'7 and operating disc 25, records variations in the position of shaft 21, hence deflections of the galvanometer. The circuitcontrolling mechanism hereinafter described is operated by the same driving means as operates recording pen 28. Shaft 5at one end through gearing 39 actuates shaft 40 carrying contact means 38 with which cooperates a moveable contact 36 actuated by shaft 21. Contact 36 is carried by a flexible connection 31 which engages driving disc 24 secured to shaft 21, disc 24 being appreciably smaller in diameter than disc 25. Flexible member 31 extends around pulleys 32 to a transversely moveable contact-shifting member 0 iii iieviiig pulleys 33 around which cord. Eli. e tends to guide pulleys moveoble contt 33. Pulleys 32 end 35 relatively so t it will apparent that s either to the right or to be shifted either to the spectiveiy, without move.- 2i.

Referring to the circu t in developed plan in If represent conducting of the cylinder, remaining portion insulating istics. ' Conductirig portions 21 and 42 ccnve in towards other tor mate to ne portions spaced to a small e other. Contact which coiitim against the cylindrical suri'oce clrcuit c troller 3d may therefore come into iodic c toot with either conducting portion ii or depending on its transverse position with spect to the said member. iiiso as contact moves further towards either extremity of mecc ber 38 it will be apparent its period oi con"- tact with the respective conducting portions will vary and will be oi longer duration.

For the purposes of illustration only, contact 36 and conducting portions 41 and d2 are shown connected by leads 3'? and 3m to a reversible motor for controlling the rate oi application of a control agent. In the specific instance shown motor 44 controls through gearing 45 a valve 46 for regulating flow or a control agent through conduit 47.

Fig. 3 shows a conventional electrical balanc ing circuit, specifically a Wheatstone bridge having an adjustable resistance 22a and moveable contact 23, and a galvanomcter G, incorporated in a control system. One arm of the Whcatstone bridge may have electrodes 50, the resistance between said electrodes varying as the c0ncentration of an electrolyte in container 52. The other arms of the bridge may include resistance 7'1, 1'2 and T3 of suitable values. Container 52 receives fluid from conduits 4'7 and 48 containing a control agent such as'acid, and water respectively. Discharge conduit 49 may lead oil the resulting solution. Y

The operation of the system and apparatus will be as follows:

Upon variation oi! the resistance between electrodes 50 Irom a predetermined standard, Wheatstone bridge 51, due to the fact that resistances 1'1, 12 and r3 do not change in value, will be unbalanced and the deflection of galvanometer' G will occur. Upon such deflection, shaft 21, and consequently discs 22, 24 and 25, will be rotated through the disengageable clutch connection between motor M, in 'a. direction depending upon the direction of deflection oi the galvanometer member. Assuming contact 36 to be in its neutral position, that is in the space between conducting portions 41 and 42, there will be no energization of motor 44 and the flow or acid or other control agent through conduit 4'7 will be at a constant rate. If, however, the galvanometer deflection should be in such direction as to indicate too high concentration of acid, shaft 21 would rotate in such direction as to move contact 36 into contact with the conducting portion which would operate motor 44 in a. direction to start closing movement of valve 46. Reversing motor-44 connected through leads 3'7 and 37a to contact 36 and commutator brushes 43 respectively, will be energized only while contact 36 is in actual conducting relation with eithor silo 32o rethat contact neutral position in the continual periodic al towards the ii balance, contact will moved away u, prev g of course ad 1 remains t position. By shifting member 341, however, in the proper direction contact 38 may be returned to its DELI-1 tral position without in any sense disturbing relation between contact 23 and slide wire rcsistehce 22a. A new control point may there i'ore be determined without changing the posh tion of circuit controller 38 since contact 36 will tend to return to its neutral position regardless of the position oi adjusting member 34.

By providing it circi' t-controller having conducting portions dive in area away from a neutral position a co. roi my be effected which is proportional to the degree of departure of the controlled condition from its desired or predetermined standard. By effecting proportional control, it is obvious that for large departures or variations the condition may be brought back to its normal value within c much smaller time than by a non-proportional control, and in addition objectionable "hunting" is prevented or considerably reduced, since the degree of control is diminished as the condition approaches its normal value.

A practical advantage in connection with the application of my circuit-controlling means to control apparatus is that the contact operating disc 24 is of smaller diameter than recording pen operating disc 25. By such difference in design of discs 24 and 25, contact 36 may be limited to a much smaller range of movement than recording pen 28, thereby preventing mechanical interiference between the two when the same are incorporated in compactly designed controlling equipment such as commonly used in commercial practice. Assuming, for example, that recording pen 28 moves through a range of 10 inches, disc 24 may be readily designed so that contact 36, for corresponding movement of pen 28, moves through a range of but 5 inches. Referring to Fig. 2 for an illustration of such operation, contact 36 will operate either within the range low" to "neutral" or high" to neutra depending on the setting of the recorder.

It will be understood that the circuit-controlling mcchanism in combination with control apparatus above described may be used in widely different control systems, such as control of a physical, chemical or electrical condition, and that the same is not limited to the specific control of acid concentration herein described.

What I claim is:

1. In combination, a deflecting member, control apparatus adapted to be actuated by deflection of said member from a neutral position, circuit-controlling means co-operating with said control apparatus, said circuit-controlling means comprising a cylindrical member having conducting portions oppositely disposed with respect to a neutral or non-conducting portion, and a contact actuated by but adjustable independently of said control apparatus adapted to intermittently engage one of said conducting portions when not within the limits of said neutral portion.

2. In combination, a deflecting member, control apparatus adapted to be actuated by deflection of said member from a neutral position, circuit-controlling means co-operating with said control apparatus, said circuit-controlling means comprising a rotatable cylinder having conducting portions oppositely disposed with respect to a neutral or non-conducting portion, said portions converging in area towards said neutral portion, and a contact element actuated by but adjustable independently of said control apparatus adapted to intermittently engage one of said conducting portions when not within the limits of said neutral portion.

3. In combination, a deflecting member, control apparatus adapted to be actuated by deflection of said member from a neutral position, circuit-controlling means co-operating with said control apparatus, said circuit-controlling means comprising a rotatable cylinder having oppositely disposed contacting portions spaced and insulated from each other, and a contact element movable parallel with respect to the longitudinal axis of said cylinder for intermittently engaging one of said portions during varying time intervals depending on the direction, and degree of deflection, respectively, of said deflection member, said contact element actuated through a flexible connection by said control apparatus.

4.' In proportional control apparatus, an electrical balancing circuit, means responsive to variations in a condition to be controlled affecting balance of said circuit, means for adjusting an element of said circuit for determining a value of said condition at which said circuit is in balance, deflecting means responsiveto unbalanced condition of said circuit, a movable control contact element actuated by said deflecting means during and in accordance with unbalance of the circuit, said contact element adapted periodically to engage cooperating contact members for periods of varying duration, common actuating means for said movable contact and said firstnamed element, and means for adjusting said movable contact element independently of said first-named element to a neutral or non-controlling position whereby the balancing position of said first-named element coincides with the neutral control position of the apparatus.

5. Proportional control apparatus comprising a deflecting member, a driven structure actuated by deflection of said member from a neutral position, circuit controlling means related to said deflecting member operated by said driven structure, a movable contact member likewise operated by said driven structure, means having a neutral or open circuit position coacting with said movable contact member for completing one of a plurality of circuits intermittently for time intervals proportional to the displacement of said movstructure, means having a neutral or open cir-' cuit position coacting with said movable contact member for completing one of a plurality of circuits intermittently for time intervals proportional to the displacement of said movable contact member from said neutral position, with change in said time intervals proportional to defiections of said first named member, and means guiding said flexible connection for adjusting said movable contact independently of said firstnamed circuit'controlling means to its neutral position thereby establishing a reference control position of said apparatus.-

7. Proportional control apparatus comprising a' deflecting member, driven structure actuated by deflection of said member from a neutral position,

circuit controlling means related to said deflecting member operated by said driven structure, a movable contact member likewise operated through a continuous flexible connection by said driven structure, means having a neutral or open circuit position coacting with said movable contact member for completing one of a plurality oi circuits intermittently for time intervals proportional'to the displacement of said movable contact member from said neutral position, with change in said time intervals proportional to deflections of said first named member, and means guiding opposing portions of said continuous flexible connection for adjusting said movable contact independently of said first-named circuit controlling means to its neutral position thereby establishing a reference control position of said apparatus.

EDGAR D. DOYLE.

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