USRE20476E

USRE20476E - Temperature controller recorder including method and apparatus

Info

Publication number: USRE20476E
Authority: US
Inventors: Charles H. Wilson; Cuthbert J. Brown
Original assignee: Foxboro Co
Current assignee: Schneider Electric Systems USA Inc
Priority date: 1928-12-14
Filing date: 1935-10-12
Publication date: 1937-08-17
Also published as: US1930496A; US1982185A; US2077451A

Description

1937- c. H. WILSON ET AL Re-.20,476 TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD AND APPARATUS Original Filed Dec. 14, 1928' '7 Sheets-Sheet 1 INVENTORS (harleg If. WZZson,

e A R A P A D N A D 0 H T E M G N I D U L G N I R E D R O C E R R E L L O R T N O fl vv E R U T A R E h E T Aug. 17, 1937. c. H. WILSON ET AL Original Filed Dec 14, 1928 7 Sheets-Sheet 2 l NVENTOR S 3 Z 7182 Charla c. H. WILSON ET AL 75 14,'12s 7 Sheets-Sheet 5 Aug. 17, 1937.

TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD AND APPARATUS Original Filed Dec.

INVENT Rs CkarZeSElf an ukb rZZBmwn .7 XMA%.@WH1ATTORNEY 7, 1937. c. H. WILSON ET AL. Re. 20,476

TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD AND APPARATUS Original Filed Dec. 14, 1928 '7 Sheets-Sheet 4 NVENZI'OR s Uharle; E 25 Aug. 17, 1937- c. H. WILSON ET AL. 20,476 TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD :AND APPARATUS Original Filed Dec. 14, 1928 7 Sheets-Sheet 5 A) PM Y o r F. 7 N m2 m NZ 5 i W i mu Z M Aug. 17, 1937. Re. 20,476 TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD AND APPARATUS C. H. WILSON ET AL Origin-a1 Filed Dec. 14, 1928 7 Sheets-Sheet 6 INVENTOR 3 672121 1635 E WZZSQIL C aZ M -U eri :ZBrozan B Q 5 ATTORNEY Aug. 17, 1937. c. H. WILSON ET AL 20,476 TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD AND APPARATUS Original Filed Dec. 14, 1 928 7 Sheets-Sheet 7 Reiseued Aug. 17, 1937 I TEMPERATURE CONTROLLER RECORDER INCLUDING METHOD AND APPARATUS Charles H. Wilson, Pelhllli M n- Assi n J. Brown, Foxboro, assignm N. Y and Cuthbert ors, by mesne cuts, to The Foxboro Company, Foxboro, Mass a corporation of Massachusetts Original No. 1,930,490,

Serial No. 326,074, December 14, 1938.

dated October 17, 1933,

Ann

eation l'or reissue October 12, 1935, Serial No.

27 Claims.

Our present invention relates to an improvement in method and apparatus for utilizing light-actuated means for causing controlled actuation of recorders, recording chronographs, autograph recorders, repeaters, pyrometer controls of the automatic furnace-temperature control type, and similar instruments of the above noted class, wherein various kinds of records and analyses are made, to which such appliances may be directed.

In the present disclosure, we have, for the purpose of outlining a characteristic, specific application of our improvement, disclosed its ready-adaptation to the control of temperature recording apparatus .as utilized in, conjunction with an automatic temperature controlling system of novel design, primarily adapted to control the temperatures of industrial furnaces. In this particular system, the predetermined temperature desired is set by manually controlled means which are related to control contacts in such system, and by means of a furnace thermocouple in control of a galvanometer, operating under the so-called null method, the 25 deflections of the thermocouple influenced galvanometer, which delicate element is freed of all mechanical incumbrance, affect the system to maintain furnace temperatures withindesired limits, as will be hereinafter described more in 30 detail.

The galvanometer herein referred to, as controlled by the thermocouple or heat sensitive current source, may be of the deflector, null method or semi-potentiometer types.

35 One of the main objects of the present improvement in recording and controlling temperatures is the joint utilization of a fixed source of light and light-actuated, current-passing means in a control circuit, such light-actuated means 40 being in either the form of the well known selenium cell or its improved equivalent, the photoelectric cell, whereby a galvanometer, operating under the influence of currents generated by a furnace heated thermocouple of any suitable 45 type, and carrying an intermittent acting light intercepting means, operative between said-light source and light-actuated current-passing means, causes initiating control operation, and cycle, of a series of associate circuits and mechanism 50 whereby to regulate furnace temperatures, whether the source of furnace heat be oil or gas fuel, electric or steam, and regardless of the kind of mechanical means involved to control the heat sources.

55 A further object of the improvement is the provision of such means upon the galvanometer whereby to control said light source and thereby a sequential acting control-or recording means, whereby said galvanometer is relieved of all unnecessary load in its performanceoi' intermittent control of the operation of associate devices and which, in its present adaptation, is utilized only to cut oil or expose a beam of light to the light sensitive means, according to predetermined cycle and setting. Thus, the galvanometer is subjected to no restraint whatever, except as to predetermined limitation of its amplitude of oscillation by stops provided for this purpose.

Another object of the herein disclosed device is to provide a light-actuated, sensitive, quickactinr' control system whereby relays may be operated to cause desired sequential operation of mechanical or electrical means of any kind other than those specifically herein referred to.

The advantages accomplished by the herein control method and apparatus are extreme sensitivity of action, speed of cycle operation, and where applied, inany of its modifications as a temperature control means for furnaces, as more specifically hereinafter outlined, the heat-treaded products from the furnace are improved in quality, are uniform and can be produced in greater quantity with a minimum of labor and fuel costs.

As will hereinafter be noted, a number of modified structures and means may be developed, but the underlying principle in all such modifications is the same, and are herein held to be equivalent, and these and such obvious modifications as are not herein disclosed are considered to be within the scope of the broader claims herein.

The principle and certain applications of this invention are diagrammatically illustrated in the accompanying drawings in which:

Fig. 1 is a diagrammatic view of an automatic recording and temperature control system embodying our invention.

Fig. 2 is a diagrammatic view of a modified form of automatic recording and temperature control system embodying our invention, illustrating the control 01'. the galvanometer-photoelectric mechanism directly from the reversible motor mechanism.

Fig. 3 is a diagrammatic view of a modified form of galvanometer, photoelectric control mechanism, illustrating the use of optical condensers and reflectors in conjunction with the photoelectric cells.

Fig. 4 is a diagrammatic view of a modified I a manually operated mechanism adapted toestablish a temperature control point.

Fig. 5 is a diagrammatic view of a modified galvanometer control mechanism for the sys- 5 tem shown in Fig. 4 showing a galvanometer actuated reflector used with a secondary curvilinear reflector of fixed type.

Figs. 6 and '7 are diagrammatic plan views illustrating the range of the light rays in the modi- 10 fication shown in Fig. 5 during operative periods.

Fig. 8 is a diagrammatic view of a galvanometer having optical means associated therewith to actuate a dual photoelectric cell control adapted, as an alternative embodiment. to be used in the systems shown in Figs. 1 and 2, showing a light reflecting means rigidly mounted on a suspended or pivoted movable galvanometer and used with a fixed double curvilinear reflector, with a single source of light and light concentration, in which the galvanometer, and its reflector are the only moving parts. a

Fig. 9 is a plan view of the means shown in Fig. 8, disclosing diagrammatically the action of the light rays and range of action thereof.

Fig. 10 discloses a diagrammatic view of a further modification of a photoelectric controlling mechanism of a similar type to that shown in Fig. 8 with fixed photoelectric cell light intercepting shields.

Fig. 11 is a plan view oi the means disclosed in Fig. 10 showing the range of action.

Fig. 12 shows a diagrammatic view of a galvanometer-actuated balanced shutter means of the type shown in Fig. 5 and adapted to be used in connection with a system such as is shown in Fig. 4.

Figs. 13, 14, and 15 are plan views of the mechanism in Fig. 12 showing, diagrammatically, certain steps in the operative scope and range of 40 the latter modification.

Referring now to the accompanying drawings. Fig. 1 discloses a furnace temperature control system, in diagrammatic outline, in which a pivoted or suspended galvanometer moving coil l is suitably mounted upon a shaft 2. The shaft 2 is supported for pivotal movement at its upper and lower ends by bearings or suspensions, not shown. The upper end of the galvanometer shaft 2 mounts a collar 3, through which is firmly'mounted a shutter stem 4, upon one end of which is carried a light intercepting photoelectric cell controlling shutter 5. The shutter is operatively associated with a housing 54 and its enclosed photoelectric cells 60, H to control the 55 action of the cells, the manner of which will be later described.

Slide wire ill, rheostat I, fixed resistance I and source of current supply 8 comprise the potentiometer circuit, the current through which is m adjusted by rheostat I and standardized by comparison against a known E. M. F. such as a cadmium cell, not shown, in the known and usual manner. The galvanometer coil l and thermocouple II are connected in series across 5 the potentiometer circuit by conductors i and I2. At point "5 the connection is fixed, the other connection being made through sliding contact I i along slide wire Ill. When the current through the potentiometer circuit is correctly adjusted,

the voltage drop between points A and "B" equals the voltage range of the thermocouple when subjected to the lowest and highest heats, so that whatever temperature, and therefore voltage, to which the thermocouple may be subiected, the sliding contact II can be moved to a point of equal .and opposite voltage along the'slide wire I. at which point, of course, the voltages being equal and opposite, no current will flow through the galvanometer coil in which case it takes up its zero'position with the shutter covering both apertures.

when: the temperature of the furnace. increases or decreases, the voltage of the thermocouple proportionately increases or decreases, causing a current to flow in either one direction or the other through; the galvanometer coil, which deflects in a direction respectively to the flow of current and uncovers either the one or the other aperture.

Heat leg of the current main II is connected to the middle tap of a controller relay coil 2., by a conductor 2|.

Within the controller relay coil 20 is mounted a reciprocable plunger 22, one end of which is pivotally attached to a pivoted switch arm 22, the pivot point 24 thereof being firmly supported by means, not shown. The arm 23 carries thereon, on its outer end, a contact terminal 25' for contact with terminal it, said terminal being insulated from the arm 23 by insulation 28. Terminal 25' is electrically connected to line 2| by a conductor 21. In its open position switch arm 23 is stopped by stop pin 22, suitably mounted.

The control relay coil 20 is connected at one of its ends to the spring terminal 20 01 a cam.- controlled closeable contact switch by conductor 29'. The opposite end of the controller relay coil 20 is connected to a second similar camcontrolled switch spring terminal 2lby a conductor 29 Thus, the lower cam-actuated

terminals

29 and 29 are located in series with the relay 20.

Both

terminals

29 and 2! are associated with cooperating upper terminals 32, these latter being insulated from

terminals

28 and 29 by-insulation 29 and being connected by conductor 22' to the heater coil l5 by conductor ll-ll'. Both cam-controlled switches are provided with con-. tact points ll-ll, in the usual manner. As the switches are shown in Fig. 1, the lower one is open and the upper one is closed.

In order to efl'ect'the control of the above noted switches, there is located below saidswitches an operative assembly comprising, generally, a reversible electric motor I! which indirectly drives two settable cams "-45, each of which is variably flxed on stepped shafts 38-. but are adiustable, as to the radial positioning of their raised cam contours 25 with scale 45, which contact with the

spring terminals

29 and 22 of the relay switches. This action will be described in detail later.

In the positions shown, the lower relay switch is open and the upper relay switch isclosed. In

this position the furnace heater coil II will be cut out of operative circuit by reason of the excitation of the rear end of'the controller relay coil, said coil being in circuit with the main It, thus drawing the switch plunger 22 to the rear and holding switch 22 in open position. Movement of the cam shaft 35 causes the cams ll3l to alter their contact positions, causing the upper cam to release its switch and the lower cam to close its switch, thereby exciting the other side of the relay 20, drawing plunger 22 to the forward position, and closing contacts |!-2l', thereby putting the furnace heater coil into closed circuit with main ii.

The cams 34-35 are provided with integral hubs 31 in which are mounted set screws 31',

some

whereby the cams are adiustably located upon shsftttsothattbeirraiaedcamcontoursflmay beradiallyrelatedorvariedtolncieaeeordecrease the related angular position of said can a contours to set the limits of temperature variationtodesireddegrees.'ibelowercamis mounted adjacent to an indicator dial it which is provided with indlces at its outer edge reading in desired temperature indications. The

shaft 46 has keyed, at its outer end, a worm wheel II and isrotatably supported in a hearing I, thisinturnbeingiixedlymounteduponabracket 41' which forms a part of the appurtenant framing. not shown.

Thescalediallllsiixedtotheshaftllwhich carries worm wheel ll, operated by worm u. The gear ratio of worm wheel ll, worm I4 and screw thread 49 are so made that whatever temperature is indicated by contact index II on the scale 8 corresponds to the temperature indicated on scale it by index 41'. y

It will thus 'be seen that radial movement of the cams "-35 in either direction from their set points ll causes controlled closing and opening of the upper and lower switches 32-32, alter-,

nately, either to start or stop'the temperaturecreating means I.

As a means for driving the above noted apparatus and other related devices herein, later to be described, there is provided the previously noted reversible electric motor 39 which is mounted upon a base plate II which may be part of the associate framing, not shown. The base also mounts a reduction gear set enclosed in the basemounted housing 40, said housing supporting a motor driven gear coupling 42, which drives the enclosed gearing. The opposite end of the housing supports a gear driven shaft 43, on one end of which is mounted a worm 44, which in turn drives 40 the cam shaft operating worm'wheel l5, previously described.

The opposite end of the gear shaft 43 is connected to a rotatable slide operating lead screw 49 which is mounted in opposite side frames 50, I

these forming a part of the machine framing. These side frames may also form a supporting means for operatively mounting a temperature record receiving roll or drum 5| which may be synchronously driven with the associate mecha- 50 nism by a timed, separate motor gear drive or clock, not shown.

The record roll-0r drum is ruled with lines 52 thereon representing the same temperature values as the index graduations on cam dial 48,

and on slide scale S, the graduations being shown enlarged at the circle K.

Operatively mounted upon the lead screw 49 is -a travelling stylus arm 58 which mounts a threaded bearing nut 54 whereby to cooperate B0 engageably with the lead screw 49. Thus, when the lead screw 49 is rotated in either direction by the motor 39, the stylus arm 53 will move to and fro along the length of the lead screw.

One end of the stylus arm 53 carries therein a recording stylus or roll marker 55 whereby to Rotationoftheleadscrewllcaus'esthestylus arm ll totraversethe lead serewandtomove the slide ll acrosstheslide wirelt, andalsotocarry thestylus ll acrossthemovlngdrumor record II.

The photoelectric mechanism which controls the operation of-the reversible motor II will now be described in detail.

There is provided, as shown at the left hand side of Fig. l, a suitable source of light such as it, of fixed intensity, the rays of which are indicated by lines II which impinge upon the galvanometer-carried shutter I.

Theshutter I is located over a housing I; the front of which is broken away in order to disclose the mounting therein of two photoelectric cells it and II. The two cells are mounted in separate compartments and enclosed in a light-proof manner. The compartments are provided on the tops thereof with light ports 02, II. Normally, these ports are shielded from the light rays 58 by shutter l so that these cells are inactive during such current fromthe motor 39. The other cell terminal II is connected through conductor 69 to the opposite leg of current supply 81. A conductor II leads from the conductor 69 to the intermediate terminal 83 of the reversible motor 39.

The second photoelectric cell BI is also con-, nected to the main current source 61 in which one terminal thereof is connected directly to said main by conductors I5, 69. The other terminal of said cell is connected to a second relay I4 through a conductor I3 and conductor 66, common to both relays 65 and I4, completes the connection of these to one leg of the main 51.

Thus, it will be seen that both cells 60 and ii are connected to, and control the flow of current from a common source 61 to control the motor 39, the details of which will now be described.

Each of the relays 65 and 14 has associated therewith motor circuit-controlling switches Ill and 16 respectively. These switches are pivotally conductor ll to an outer terminal 84 on the motor 39. The other switch 16 is connected through a conductor 18 to the main 51, this latter conductor being common to both contacts X.

When the switch 10 is drawn towards its associated relay 65 by actuation of the cell 60, the switch contacts with terminal II. The terminal H is connected by conductors I2, 18 to one leg of the main 61. The opposite circuit to the motor is through conductor 8| to motor terminal ll, thence to return by intermediate motor terminal 83, conductor to opposite leg of main 61, thus completing the circuit controlled by cell 60.

The operation of the opposite circuit controlled by cell II to motor 39 is through switch contact II to switch Ii to common conductor 18 to one leg of the main 61. From contact 11 through conductor I9 to motor terminal 82 thence through intermediate motor terminal conductor 80 to opposite leg of main 81.

10 thermocouple in series with the galvanometer coil connected across potentiometer circuit from "A" to II, a current would flow from the potentiometer circuit through the galvanometer circuit deflecting the galvanometer in such a direction 15 as to uncover one of the photoelectric cells which would energize the motor in a direction that would turn the worm M and lead screw 99 and it would keep turning until the slide l I had reached a point on slide wire II where the voltage of the thermocouple equaled the voltage drop from A.

toil.

The voltage from the thermocouple then equal ing the voltage from A to II and being in the opposite direction, no current would flow through 25 the galvanometer and the pointer would return to its zero position covering both ports.

The motor, in turning the lead screw, would operate the pen and

stylus

94 and 59 to draw a record of this travel and at the same time it would 39 turn worm wheel 45 and the contact operating cams attached thereto and so close contact switches 29 and 92 to shut the furnace switch 29.

Should the temperature of the furnace rise above the predetermined setting the voltage generated by the thermocouple would be greater than the drop in vvoltage between A and Ii. Current would then flow through the galvanometer in the oppo site direction causing the galvanometer to defleet and uncover the other photoelectric cell which would operate the motor in the opposite direction so that contact switch 29 would be opened and contact switch 29 closed, so energizingthe plunger'circuit 22 to open the contact switch 22.

The earns 95 and 29 being adjusted in their radial position to the dial 49 which is in definite relation to the position of the sliding contact iridex II on slide wire scale S so that when the temperature, or the voltage, rather, of the thermocouple varies from that drop across the slide wire from A to II ,the galvanometer swings to uncover either one of the cells energizing the motor in such a direction as to bring the contact ll back to the point of equal voltage and at the same time it operates earns 94 and 99 to switch on or switch off the heater coil II in the furnace.

Thus increase or decrease of temperature within the furnace causes the galvanometer to respend and to move the shutter I, which in turn causes responsive automatic control of the apparatus to hold the temperature within desired limits.

In this way, not only is a control record obbut ' an automatic temperature control obtained which operates in synchronism with the graphic recording means. 4

The modification shown in Fig. 2

In this system illustrated in Fig. 2 is shown a modification of the system disclosed in Fig. 1. Since many of the cooperating devices and cir- .cuitsshowninFigJaresimilartothoseshown 75 in Fig. l, in structure and function, in some intained of the performance of the furnace, but

1 v stances like indices as in Fig. -1, will be used for like structures.

The galvanometer coil l is arranged in series with the thermocouple l9 anda calibrating resistance 99. The galvanometer coil is suspended by a torsionable flat suspension spring 9| from rotatable disk shaftjl which carries a driven worm wheel dial 99 having temperature indicia 94 inscribed on the face thereof. The reversible motor 99 by means of-a worm and worm gearing 99, 99, drives a shaft 99 upon which is fixed a dial driving worm 91 which drives the dial in. A lead screw extension 99, mounted on the end of the shaft 99, mounts a threaded stylus arm 99 thereon for reciprocation by means of its threaded hub or an equivalent I99.

An alternative stylus arm structure shown dotted in this view may be attached directly to the dial 9!, permitting the members 99 and I99 to be dispensed with. The stylus 59 and recording means may be arranged as described for Fig. 1. In this structure when the motor 39 rotates in either direction, through the

reduction gearing

99, 99, 99, 91, it directly and mechanically influences the movement of the galvanometer to return to a position of balance through torsion of the galvanometer suspension spring 9i A change in thermocouple current causes the galvanometer to deflect from its point of balance thereby exposing either of the cells 99, ii to the rays from the light source 39.

Thus, rotation of the motor 39 rotates the dial shaft 9| creating a torsional tension on the flat spring suspension 9|. The direction of dial shaft rotation is opposite to the deflection movement of the galvanometer; therefore the galvanometer is influenced by thermocouple current to initiate temperature control and recording changes and is mechanically restored to balanced position.

As a. means for causing the above noted control and recording. sequences, a vertical shaft 921s arranged to rotate in a hollow support bearing "I which carries an index point I92 rigidly ailixed thereto, these being part of the frame mounting, not shown. The shaft 92 further has a pair of cams I99, I99 rigidly, but adiustably, attached at its upper end. Thus, the shaft 92, cams I93, I94 may be rotated as a unit relative to the index point I92. The cams are independently radially adjustable on the shaft similar to that shown and described for Fig. l. A furnace heater switch control means C-D, controlled by cams I99 and I99, respectively, controls the current supply to the furnace heater coil l5. Since this cam and switch mechanism is similar to that shown and described in Fig. 1, the details will not be repeated. 1

Both switches C, D, are connected to a relay coil 22, switch 23 and supply mains It, as in Fig. l. The operation of this modified system is similar in most respects to that shown in Fig. l. The index pointer I92 in this case is fixed and the worm dial 92 movable.

The thermocouple being approximate to the furnace heat, then generates a'current which would flow through the galvanometer circuit. The calibration resistance 99, Fig. 1, having been adjusted so that the current through the galvanometer circuit would have a deflecting force on the galvanometer coil which would equal the torsion of the other end of the suspension spring set up by the scale index to correspond with the temperature in the furnace. As for example, if the index I92 pointed to the scale division of 1000 degrees of temperature and if the temperature of the thermocouple in the furnace was also 1000 degrees, the current which would flow through the galvanometer coil would hold the shutter at a point of balance, shutting off the 6 light from both ports, and if the temperature of the furnace and, therefore, the thermocouple current varied from this degree of temperature, it would uncover either one or the other of the photoelectric cell ports and so energize the motor in one direction or the other to restore the'point of balance on the galvanometer coil and at the same time would open or close switch C or D to switch on or switch ofl the heater current in the furnace.

The modification shown in Fig. 3

Fig. 3 shows a modification in the galvanometer control structure shown in Figs. 1 and 2. Like numerals are used to indicate elements in Fig. 3

which are similar to like elements shown in Figs. 1 and 2. A galvanometer coil I is suspended by a wire support 8|, which passes through a cylindrical collar 3. The collar 8 has rigidly afllxe'd thereto a stop mu IIII engageable with a rigidly supported stop plate III, and also a shutter bar I which mounts a V-shaped reflector I I2 at its outer end, as a substitute for the shutter 5 of the previous figures.

The coil is connected to the thermocouple mechanism as shown in Figs. 1 and 2. The V--shaped mirror I I2 is arranged at the end of arm 4, in a position to be over the light ports 63, 82 of the photoelectric cell box 58, which houses the photoelectric cells 60, 6|. Two light sources 38, one

light through condensing lenses 8, so as to concentrate the light on the opposite faces of the mirror II2.

The mirror is so arranged that when the gal- 40 vanometer coil I is at rest or zero position, the light rays will not be deflected into the ports 88 or 62. Any deflection of coil I, results in the mirror being moved to the right or left, thus deflecting light into one or the other of the ports A diaphragm stop H3 may be interposed between the light sources 38 and the lens II3 for the purpose of definitely focusing and confining the light rays upon the mirror faces.

50 The stop pin IIII cooperates with the raised lugs of the stop plate III to restrict the oscillation of the shutter bar within desired limits.

Thus, this modification shows a dual light means with suitable light modulation and reflect- 55 ing means for the control of the photoelectric cells.

The modification shown in Fig. 4

Fig. 4 illustrates a temperature control system 60 applying the basic principles disclosed heretofore, wherein the galvanometer I and thermocouple I3 are arranged in a potentiometer cir-.

cult, except that no provision is made herein for recording the temperature changes. As before,

65 a furnace It has positioned therein a thermocouple I3 and heater resistance IS. The thermocouple I3 is connected to the galvanometer coil I which is supported by a suspension wire 8i from a solid support, not shown. The wire passes 70 through a cylindrical collar 3, to which is rigidly afiixed the shutter arm 4 carrying a shutter 5 at the extreme end thereof.

The thermocouple is connected by a conductor I24 to a slide IIS which slides .over a potenti- 5 ometer resistance I20. The threaded slide hub mounted on either side of mirror II2, project- 5 Dis moved along a lead screw II'I rotatably mounted in bearings III by the manual rotation of a knurled head of the lead screw. A scale and index pointer, not shown, may be arranged parallel to the length of the lead screw to provide for predetermined temperature reading index.

The potentiometer slide wire I28 is placed in series in a. potentiometer circuit with a rheostat I22, a source of E. M. 1''. I22 and fixed resistance I2I. The'thermocouple II in series with galvanometer I is connected to the potentiometer circuit by connection I II at a fixed Point F, and f by connector I24 through sliding contaq II! on the slide wire I20. The cell I26is connected on one side directly to oneleg of the main current supply 1 by conductor I28 and is connected on the other side through relay coil I28 to the other leg on the moved in the direction of the arrow A by a slight amount, the port I32 is uncovered and the relay I28 excited by cell I26 to close the circuit I21, I38, I5, I39, I28, I30 to I21, thus passing current from the main I2I through furnace resistor I5 and cause a temperature rise in furnace l4.

Should the shutter be moved in a direction opposite to the direction of the arrow, however, it would not uncover the light port, but merely move over to stop 85 without uncovering said port.

In operation, as shown in Fig. 4, the slide H5 and rheostat I23 have been set to send a predetermined E. M. F. through the thermocouple and potentiometer circuits. -If the E. M. F. generated by the thermocouple becomes greater or less than the opposing potential diflerence of the potentiometer circuit, the coil I will be deflected from its zero point.

, If the deflection of the coil I is in such direction as to uncover the port I32 above the cell I28, then the relay I28 is energized. This results in the armature I30 making contact with I28 and current passed through I5. Thus, the temperature is regulated to be increased. Should the temperature get too high, the thermocouple E. M. F. becomes greater than the potentiometer E. M. F. and the coil I is swimg to port covering position.

The modification shown in Figs. 5 to 7 inclusive In these figures there is shown an optical modification of the .galvanometer temperature control mechanism, without recording, shown in Fig. 4. This optical arrangement may be used as an equivalent of the shutter-mechanism shown in Fig. 4:.

Light beams E from the light source 38 are concentrated by a lens I on a mirror I4I carried by the galvanometer I. The beams are then reflected onto a fixed, curvilinear mirror surface I, said mirror having the form 'of a right section of a hollow elliptical cylinder. In this case, the inner surface is the reflecting surface.

The beams are reflected from galvanometer mirror I to the photoelectric cell I25, housed in'a box I25, Fig. 5, through reflection from mirror I. To provide a cut-oil point for the light beams E, a light cut-oil stop or diaphragm 5 I4! is interposed between the mirrors "I and I44. The stop I4! may also be placed between the cell I25 and mirror I44. A portion of the mirror I44 may be left unsilvered and the beams thus absorbed on this surface on mirror I44.

'10 The-mirror I44, geometrically, is a section of a hollow, right, elliptical cylinder. The galvanometer coil I and cell III are'so arranged that the axis of the coil I and the sensitive plate oi the cell III are each locatedon a line 1'', in the plan 1 views of Fig. 5, as shown in Figs. 5 and 'L'said line passing through one of the foci of the ellipses formingthe top and bottom boundaries of the elliptical mirror I44.

. Since from the law of the ellipse, the tangent The modification shown in Figs. 8 and 9 Fig. 8 shows an optical arrangement to be applied to a system as shown in Figs. 1, 2, and 3, including temperature-control and recording, the arrangement here shown being used to replace I the shutter mechanism in Figs. 1 and 2, and the mirror structure-in Fig. 3.

The coil- I, of the galvanometer, carries a flxed mirror I, as explained in Figs. 5-7 inclusive, 40 which reflects a beam F onto a compound elliptical mirror I44--I44'. The arrangement shown in Fig. 8 is similar to that in Fig.5, but the cells and mirror are duplicated. Two cells m, I26 encased in housings I25, I25 receive the angularly reflected beam F from the single light source 55, through condenser lens I40 to the galvanometer mirror I and thence to either elliptical mirror surfaces I44, I44.

The light beams F from source 55 are concentrated by a lens I40 on the mirror I. When the coil I is in rest or zero position the beam F strikes the mirror I and is reflected to the intersection I45 of the two surfaces I44, I44. An unsilvered strip may be left at this point for 55 the light beams to be absorbed, or a diaphragm may be interposed in-front of said intersection,

or the light beams maybe passed through a slot at this point, not shown. It is understood, of course, that instead of a compound mirror. separate mirrors, shaped as shown, may be substituted.

The two mirror surfaces I44, I44 are so located that the foci all lie on the same straight line and two of the fool, one for each ellipse, are coincidental. The concave faces of both mirrors are toward mirror I, as shown in the plan view, Fig. 9, and the pivotal axis of the galvanometer I passes through this coincidental foci point. The

7 shielded cells I25, I25 are positioned on either side of the mirror I, as shown.

The operation is obvious. The deflection of the coil 1 in either direction casts a beam E or E upon the mirror surfaces I44 or I 44' and, being 75 reflected, thus activate either of cells I25, I26.

sired limits.

' mirror from a constant light source 35 by a con- The modification shown .iaFias. 10 and 11 This is an optical arrangement adapted to be applied in the same manner as that shown in Fig. 8 and carries with it similar features to the photoelectric cell control shown in Fig. 2, and may be utilized for both temperature control and recording. The .galvanometer coil I carries a tired mirror I on stem I50 afllxed thereto. A shaft I5I mounted in said stem I50 and at right angles thereto cooperates to function as a limiting stop arm. The end of shaft I5I extends into and cooperates with the limiting lugs on step I52, to restrict the deflection of the coil I to the de- The photoelectric cells I55, I54 are positioned in opposite compartments formed by partition I51 which divides the supporting basefl53. A light intercepting baille I55 is positioned at right angles uponand to the partition I51 and serves asa single shield for the two photoelectric cells I54 and I55 and normally serves to shield the cells from the beams G reflected from mirror I when the galvanometer mirror I is in zero position. The beams are concentrated on the denser lens I40.

As shown in the plan view in Fig. 11, when the mirror I is in zero position and undeflected,- the beams G are projected upon the bum I55 and are absorbed. when the mirror is in deflected position the beams, H are reflected to either side of the baiiie I55, and the incident beams H are projected upon the cells I54 or I55 and cause' actuation of the temperature controller-recording means such as is shown in Figs. 1 and 2.

The modification; shown in Figs. 12 to 15 inclusive Herein is shown a modification of the galvanometer controlled mechanism as disclosed in Fig. 4. In this form, a pair of axially opposed shutters I5I, I5I are afllxed to the galvanometer shaft I54 for movement therewith. The shaft I54 is attached to the galvancmeter I which is pivotally supported upon suspension wires 9|. The coil and shutter assembly is mounted between a pair of diaphragm stops I55, I55, both of which are provided with diaphragm apertures I58, I55 respectively. l

The two aligned shutters I60, I5I are provided with cut-out sections I52 and I53 whereby to pass light through apertures I55, I59 when the galvanometer is out of zero position. When the galvanometer is moved into zero position, the bailie portions I52'I53' are brought into light axis H and prevent light from passing to the single 55 photoelectric cell I5I. This arrangement permits 01' providing twice the amount of light opening to the photoelectric cell for the same amount of galvanometer deflection as hereinbefore-disclosed, and at greater speed.

Shutter limiting stops ilil, I1l are mounted upon the baflle I55, adjacent the shutter I5I, to limit the deflection of the galvanometer, as heretofore.

The detailed operation of this modification is shown in the plan views in Figs. 13, 14, and 15. When the coil is in rest or zero position, Fig. 13, light passes through diaphragm I55, but is prevented from passing further through diaphragm 7 I59 to cell I51 by the blocking action of the portions I52'I53 ofthe shutters I5I'I,I5I.

In the plan view, Fig. 14, the coil I and shutter lill-ISI are shown to have been deflected out of zero position to render cell I61 inactive. In this 7 some position the baiiie portions l82'l0l' of the shu ter prevent the light passing through aperture I66 to the cell I61.

"In the plan view, Fig. 15, the shutters are shown in opposite or cell activating position, the galv fi nometer coil l having been moved to opposite position to that shown in Fig-14, the baiiies I", ISI being deflected out of the path of beams H thereby uncovering the apertures IOU-I89 and passing light from 38 through to cell I".

It should be understood that these various galvanometer controlled mechanisms may be used with either of the'systems shown in Figs. 1, 2, or 4,

as our invention is not limited to the specific details illustrated or to the specific arrangement thereof, since various modifications may be made therein within the spirit of the invention and the scope of the appended claims.

We claim:

1. A light responsive control mechanism comprising a casing, a partition'dividing said easing into two compartments, a photoelectric cell in each compartment, a galvanometer coil adapted to be deflected, a reflecting surface operatively associated with said coil, a deflection limiting mechanism associated with said coil and surface, a source of light normally in non-activating position relative to said cells, a lens to concentrate light from said source upon said surface, a light obstructing member associated with said casing and adapted to obstruct the passage of light reilected from said surface when said coil is in nondeflected position only, said limiting mechanism being positioned. and constructed to prevent said reflecting surface from passing light beyond the cells.

2. An automatic heat control mechanism ineluding a furnace, a heating means therefor, and means associated with said heating means to 40 control the temperature of said heating 'means comprising a motor and motor circuit, adjustable means operatively interposed between said motor and said heating control means to limit the temperature of said heating means, a source of variable current responsive to the action of said heating means, a galvanometer circuit actuated by said current, a potentiometer circuit connected to said galvanometer circuit and in equilibrium therewith, a source of light, a light-actuated motor circuit current passing means, and means influenced by the action of the galvanometer potentiometer circuit to vary said light source upon said current passing means.

3. An automatic heat controlmechanism including a furnace, a heating means therefor, and

means associated with said heating meansto control the temperature of said heating means I comprising a motor and motor circuit, settable means operatively interposed between said motor and said heating control means to limit the temperature of said heating means, a source of variable current responsive to the action of said heating means, a galvanometer circuit actuated by said current, a potentiometer circuit connected to said galvanometer circuit and in equilibrium therewith, a source of light, a light-actuated current passing means located to control said motor circuit, means influenced by the action of the galvanometer-potentiometer circuit to vary said light source upon said current passing means.

4. An automatic control mechanism including a furnace, a heating means therefor, and means associated with said heating means to record the temperature of said heating means comprising a 5 motor and motor circuit, recording means opera- 7 means, andmeans influenced by the action of the tively associated with said motor circuit and cogalvanometer potentiometer circuit to vary said light source upon said current passing means.

5. A control mechanism comprising a source of variable current responsive to a condition to be examined, a galvanometer circuit actuated by said current, a potentiometer circuit connected to said galvanometer circuit, movable indicator means for maintaining said potentiometer circuit in equilibrium with the galvanometer circuit, a source of light, a light-controlled current passing stationary means, and means influenced by the action of the galvanometer potentiometer circuit to vary said light source upon said current passing means, and means controlled by the current passing means to control said movable means. I

6. A control mechanism comprising a source ofvariable current responsive to a condition to be examined, a galvanometer circuit actuated by said current, apotentiometer circuit connected to said galvanometer circuit, means including a\ movable part for maintaining said potentiometer circuit in equilibrium with the galvanometer circuit, a source of light, a light-controlled current passing stationary means, and means influenced by the action of the galvanometer potentiometer circuit to vary said light source upon said current passing means, and recording means actuated by said movable part. I 7. An automatic heat recording mechanism for a furnace having a heating means, said recording means being associated with said heating means for recording the temperature in said furnace, said recording means comprising a motor and motor circuit, a source of variable current responsive to the action of the heat in said furnace, a galvanometer circuit actuated by said current, a potentiometer circuit ,connected to said galvanometer circuit and comprising a variable resistance controllable by the motor to keep the potentiometer circuit in equilibrium with the galvanometer circuit, a source of light, a lightactuated current passing means located to control said motor circuit, means influenced by the action of the galvanometer-potentiometer circuit to vary said light source upon said current passing means, and a recording device operated by said motor for recording the temperatures of said furnace.

8. An automatic heat recording mechanism for a furnace having a heating means, said recording mechanism comprising a motor and motor circuit, a source of variable current responsive to the action of the heat in said furnace, a galvanometer circuit actuated by said current, a potentiometer circuit connected to said galvanometer circuit and including variable means controlled by the motor for maintaining the potentiometer circuit in 'equilibrium with the galvanometer circuit, a

source of light, a light-actuated motor circuit current passing means, and means influenced by the action of the galvanometer-potentiometer circuit to vary said light source upon said current means.

9. A control mechanism comprising a source of variable current responsive to a variable condition, a galvanometer circuit actuated by said cinrent, a potentiometer circuit connected to said galvanometer circuit, movable means for main- 5 taining said potentiometer circuit in equilibrium with the galvanometer circuit, a source of light, a light-controlled current passing means, and means influenced by the action of the galvanometer potentiometer circuit to vary said light 10 source upon said current passing means, and a translating means controlled by the light passing means.

10. A control mechanism comprising a source of variable current responsive to a condition to 15 be maintained, a galvanometer circuit actuated by said current, a potentiometer circuit connected to said galvanometer circuit, means including a movable part for maintaining said potentiometer circuit in equilibrium with the galvanometer cir- 20 cult, a source of light, a light-controlled current passing means, and means influenced by the action of the galvanometer potentiometer circuit to vary said light source upon said current pass-: ing means, and means controlled by said movable 25 part for controlling said condition.

11. An automatic heat recording and control mechanism including a furnacefa heating means therefor, and means associated with said heating means to control the temperature of said heating means comprising a motor and motor circuit, a shaft positively rotated by said motor in constant ratio therewith; settable cams carried on said shaft, switches operated by said cams to control said heating control means to limit the tempera- 35 ture of said heating means, a source of variable current responsive to the action of said heating means, a galvanometer circuit influenced by said current, a source of light, light-sensitive stationary current passing means located to control said 40 motor circuit, and means immediately influenced by the action of the galvanometer to vary the eiiect of said light source on said light-sensitive means.

12. An automatic heat recording and control 45 mechanism including a furnace, a heating means therefor, and means associated with said heating means to control the temperature of said heating means comprising a motor and motor circuit, adjustable settable means operatively inter- 50 posed between said motor and said heating control means to limit the temperature of said heating means, a. source of variable current responsive to the action of said heating means, a galvanometer circuit influenced by said current, a

' 55 source of light, a light-actuated current pasing means located to control said motor circuit, means influenced by the action 01' the galvanometer to vary said light source upon said current passing means.

13. In combination, a furnace, a heating means therefor, and a heat-controller mechanism controlled by the heat of said furnace comprising a motor and motor circuit, a source of variable current responsive to the action of said heating means, a galvanometer circuit actuated by said current, a potentiometer circuit connected to said galvanometer circuit and in equilibrium therewith, a pair of light-actuated current passing means located to control said motor circuit 7 for rotating the motor in opposite directions respectively, means influenced by the action of the galvanometer-potentiometer circuit to control said current passing means respectively, and translating means operated by said motor.

75 14. A light responsive control mechanism comsome prising a pair of adjacent photoelectric cells, a single light bai'iiing means separating said cells, a galvanometer coil adapted to be deflected, a light controlling means operatively associated with said coil, a source of light, cooperating with said controlling means to cause the light from said source to fall on one cell when said controlling means is in one position, and on the. other when in another position, said controlling means being movable by the coil in a plane of movement Pe pe dicular to the axis of movement'of the coil and disposed at an angle to the rays from said source to said plane.

15. A ght responsive control mechanism comprising a pair of adjacent photoelectric cells, a pair of compartments housing said cells respectively and comprising a single opaque partition separating said cells, a galvanometer coil adapted to be deflected, a light controlling means operatively associated with said coil, a source of light normally in non-activating position relative to said cells, and cooperating with said controlling means to cause the light from said source to fall on one cell when said controlling means is in one position, and on the other when in another position, said controlling means being movable by the coil in a plane of movement perpendicular to the axis of movement of the coil and disposed at an angle to the rays from said source to said plane.

16. In combination, a furnace, a thermocouple therein, adjustable heating means for the furnace, a galvanometer, a potentiometer circuit including said galvanometer and thermocouple and comprising a variable resistance, having a movable means, by which the potentiometer circuit may be placed in equilibrium, a motor having a constant ratio connection with said movable means for adjusting said movable means, light controlled current passing means immediately influenced by the action of the galvanometer for supplying positive or negative current to said motor to run the motor forward or backward, thereby to control immediately the motor whenever and as soon as, and as long as, said influence takes place, and additional visible movable means controlled by the action of said motor, and moved in opposite directions when the temperature of the furnace is raised or lowered to indicate movement of the adjustable means and adjustment which ought to be made by the heating means.

17. In combination, a furnace, a thermocouple therein, adjustable heating means for the furnace, a galvanometer, a potentiometer circuit including said galvanometer and thermocouple and comprising a variable resistance, having a movable part, by which the potentiometer circuit may be placed in equilibrium, a motor for adjusting said heating means, a stationary light-controlled Y current passing means immediately influenced by the actionoi the galvanometer to vary the action of the current passing means, for immediately supplying positive or negative current to said motor to run the motor forward or backward, thereby to control immediately the motor whenever and as soon as, and as long as, said influence takes place, and additional visible movable means controlled by the action of said motor, and moved in opposite directions when the temperature of the furnace is raised or lowered to indicate adjustment made by the heating means.

18. In combination, a furnace, a source of current responsive to the temperature in the furnace, a galvanometer circuit actuated by said current and comprising a galvanometer in the circuit, a potentiometer circuit connected to said galvanometer circuit and comprising a variable resistance, having a movabl part by whiclmthe potentiometer circuit is p in equilibrium with the galvanometer circuit, a motor having diately the action of the-motor whenever and as soon as said influence takes place, and temperature recording means for the furnace controlled by said motor.

19. In combination. a furnace, a thermocouple therein, adjustable heating means for the furnace, a galvanometer, a potentiometer circuit including said galvanometer and thermocouple and comprising a variable resistance, having a movable part, by which the potentiometer circuit may be placed in equilibrium, a motor having a. constant ratio positive connection between said motor and said movable means for adjusting said movable means, and heating means, a stationary current passing means immediately influenced by the action of the galvanometer to vary the action of the current passing means for immediately supplying positive or negative current to said motor to run the motor forward or backward, thereby to control immediately the motor whenever and as soon as, and as long as, said influence takes place, and recording means controlled by the action of said motor, including a marking means moved in opposite direc-' tions whenever and as soon as the temperature of the furnace is raised or lowered to indicate adjustment made by the heating means, and to .record adjustments of the heating means and current passing means, immediatelylinfluenced by the action of the galvanometer to vary the action to record temperature changes at all times when the heating means is not being adjusted.

20. In combination, a furnace, a source of current responsive to the temperature in thefurnace, a galvanometer circuit actuated by said current and comprising a galvanometer in the circuit, a potentiometer circuit connected to said galvanometer circuit and comprising a variable resistance, having a movable part, by which the potentiometer circuit is placed in equilibrium with the gal'vanometercircuit, a motor for adjusting said movable means, a source of light,

a stationary light-controlled current passing means for supplying current to said motor, means influenced by the action of the galvanometer to vary the action of the light on the current passing means, thereby to vary immediately the action of the motor whenever and as soon as said influence takes place, and adjustable heating means and temperature recording means for the furnace controlled by said motor, said recording means recording changes in the heating means as soon as they take place, and recording temperature changes substantially as soon as and whenever they take place.

21. In combination, a furnace, a thermocouple therein, adjustable heating means for the furnace, a galvanometer, a potentiometer circuit including said galvanometer and thermocouple and comprising a variable resistance, having a movable part, by which the potentiometer circuit may be placed in equilibrium, means for adjusting said movable means, means including a magnet controlling said heating means, a light-controlled of the light on the current passing means for immediately supplying current to said magnet thereby to control immediately the magnet whenever and as soonas and as long as, said influence takes place.

22. A control mechanism comprising condition sensitive means, balancing means connected with said condition sensitive means for returning the condition sensitive means to a null point upon departure therefrom, and translating means controlled by said balancing means for indicating the balancing force necessary to maintain the condition sensitive means at the null point, and stationary light sensitive means controlled by said condition sensitive means for controlling.

the operation of said balancing means.

23. A control mechanism comprising means having a variable electrical characteristic responsive to a condition, electrical means responsive to said characteristic, a balancing circuit, said first named means and said electrical means being electrically connected into said balancing circuit, means including a movable part for balancing said balancing circuit when unbalanced by variation of said variable characteristic, a beam of light, light sensitive stationary means for controlling the operation of said movable part for balancing said circuit, and said electrical means controlling said light sensitive means by controlling the light aflecting said light sensitive means.

24. A control mechanism comprising means having a variable electrical characteristic responsive to a variable condition, electrical means responsive to said characteristic, a potentiometer circuit connected with said first named means and said electrical means, movable means for balancing said potentiometer circuit, light-controlled means for operating said movable means, and means influenced by said electrical means for operating said light-controlled means.

- 25. In combination, means to be heated, means for controlling an agent influencing the temperature of the means to be heated, means havsive to the temperature of the means to be heated, electrical means responsive to said electrical characteristic, a balancing circuit electrically connected to said variable characteristic means and said electrical means and having a variable resistance by which the circuit maybe balanced, a motorfor adjusting said variable resistance, stationary light sensitive means for controlling the supply of current to said motor, said electrical means controlling the operation of said light sensitive means to vary immediately the action of the motor whenever, and as long as, said balancing circuit is out of balance, and an additional movable visible means controlled by the action of said motor moved in one direction when the temperature is raised and in the opposite direction when lowered to indicate adjust ment made to the variable resistance.

26. A light responsive control mechanism comprising a plurality of light sensitive means placed side by side, means to prevent light while affecting one of; said light sensitive means from affecting the other light sensitive means, a condition sensitive element adapted to be deflected, a refiecting surface movable responsively to said condition sensitive element, a beam of light normally in non-actuating position relative to the light sensitive means, light obstructing means associated with said light sensitive means to prevent light reflected from said surface from aftecting said light sensitive means when said condition sensitive element is in a certain position only, and limiting means for limiting the movement oi said surface for preventing said surface from reflecting said beam in such a manner as to render the instrument inoperative.

27. A light responsive control mechanism comprising a plurality of photoelectric cells arranged side by side, means for preventing light 10 eating one cell from similarly aifecting an ad- Jacent cell, a condition sensitive element adapted to be deflected, lllht controlling means operativethe axis of movement 01 the condition sensitive element and disposed at an angle to the rays from said source to said plane.

' CHARLES H. WILSON.

CU'I'HBERT J. BROWN.