US2354391A - Machine control - Google Patents

Description

July 25, 1944. A. R. MccouRT 2,354,391

MACHINE CONTROL Filed July 3, 1942 4 Sheets-Sheet 1 Irzventar Jrflur FM'Ja tor-Z July 25, 1944. A. R. MCCOURT MACHINE CONTROL Filed July 5, 1942 4 Sheets-Sheet 2 Inventor J w w m m r 3E9: K849 O O E- Q .m

w f Lam mi d m 4 T W \N. m .w QM A July 25, 1944. A. R. McCOURT MACHINE CONTROL Filed July 3, 1942 4 Sheets-Sheet 3 Lu N RN 1/ M g I m/entar M gag/W zm July 1944. A. R. MccouR'r 2,354,391

MACHINE CONTROL Filed July 3, 1942 4 Sheets-Sheet 4 I\ Q t 2 b 5 Q l N T Q N w s: m m x U- k N s & TX w &

If 4H m a a q t b '1 Invenior fliiorn e ys Patented July 25, 1944 UNITED STATES PATENT OFFICE 2,354,391 MACHINE CONTROL Arthur R. McCourt, Butte, Mont. Application July 3, 1942, Serial No. 449,633

3 Claims. I (Cl. 172-239) The invention relates to improved means for controlling the operation of a machine by means of a conductive line or strip on a prepared chart,

so as to make the machine substantially inde-- pendent of an attendant while in operation, and the prirrlary object of the invention is to provide a simple, reliable, and relatively inexpensive arrangement of this character.

Other important objects and advantages of the invention will be apparent from a reading of the following description taken in connection with the appended drawings, wherein for purposes of illustration a preferred embodiment of the invention is shown.

In the drawings:

Figure 1 is a general top plan view of the device showing a prepared chart in position.

Figure 2 is a general vertical longitudinal sectional view taken through Figure 1.

Figure 3 is a fragmentary transverse vertical sectional view taken through Figure 2 along the line 3-4 and looking toward the left in the direction of the arrows.

Figure 4 is an enlarged fragmentary transverse vertical sectional view taken through Figure 3 along the line 4-4 and looking toward the right in the direction of the arrows.

Figure 5 is a perspective view of one of the contact points.

Figure 6 is a fragmentary perspective view of the outer end of the lead screw mechanism.

Figure '7 is a perspective view of the point carrier. I

Figure 8 is a schematic wiring diagram showing the electrical connections involved in the device.

Figure 9 is a schematic view showing the conductive ink line moving in a direction at right angles to the lead screw.

Figure 10 is a schematic view similar to Figure 9 in which the ink line takes an abrupt turn so that part of the line lies parallel with the lead SCI'CW.

Figure 11 is a similar view in which the ink line takes an abrupt turn in a direction parallel to the lead screw.

Figure 12 is a diagrammatic view of a servomotor forming a connecting link between the electrical wire and the governor for the turbine.

Referring in detail to the drawings, the device may suitably comprise a horizontal base 5 upon which normally rests a flat block 6 which is hinged on a transverse axis as indicated by the numeral 1 to the left hand end of the base 5. A reversible electric motor 8 is mounted on the block 6. The left hand end of the motor shaft is provided with a pinion 9 which is adapted to be geared to the machine to be controlled. This link connection is indicated in Figure 12. The opposite end of the motor shaft is provided with a pinion III which is meshed with a gear I I which is fixed on the lead screw 12 one smooth end portion of which is mounted in an L-shaped bracket 43 secured to the right hand portion of the top of the block 6, the outer and smooth end portion being journaled in a, bracket ll which is rigidly supported relative to the 'bracket [3 .by means of fixed rods l5 and I6 which are anchored in the two blocks on the upper and lower sides of the lead screw. The rods l5 and It also function as slide guides which pass through the upper and lower smooth bores I1 and IS in the contact point carrier which is generally designated IS. The upper end portion of the carrier is provided with a threaded bore 20 located between the bores I1 and I8 in which the lead screw I2 is threaded. The carrier I9 is preferably of dielectric material or is suitably insulated and is equipped also with a foot portion 2| which has longitudinally spaced binding post holes 22 and 23, respectively. Between the binding post holes are two laterally longitudinally spaced pairs of contact point mounting holes. The contact points, of which there are two, are severally designated by the numerals 26 and 21, although of similar construction and arrangement. Each contact point consists of an inverted U-shaped wire having a longitudinally inwardly deflected extension 28 on one leg thereof, the lower terminal of the extension being arranged to ride on the chart 29 which is laid upon and fixedrelative to theturn table 30. wardly through the pairs of holes 24 and 25 so that the extensions 28 depend below the foot portion 2| of the carrier to engage the chart, while the shorter leg remains above the level of the chart. Reclining J-shaped flat springs 3| and 32 have their standard portions pressing downwardly on the bight portions of the contact points as illustrated in Figure 4 of the drawings so as to urge the extensions 28 into engagement with the chart. The crook portions of the springs are anchored by the binding post screws 33 and 34 which are threaded in the binding post holes 22 and 23 in the foot portion of the carrier.

The turn table 30 is a disk of suitable material to revolve evenly and present a level surface and includes a hub 35 from which depends a reduced spindle 36 which is journaled in the base 5, the spindle having a gear 31 on its lower end in mesh with the gear 38 of a suitable synchronous driving mechanism, such as the clockworks 39 which drives the turn table 30 at a predetermined timed rate. The top of the turn table has a central hole 40 to receive the aligning lpin 4| on the lower end of the bracket H of the lead screw mechanism, so that when the lead screw mechanism is swung downwardly from an upwardly hinged position (not shown) to the operative p0- The arms of the contact point pass downsit-ion, the pin 4| is entered in the hole 40 to center and align the entire mechanism.

The chart 28 may be in the form of circular graph 42 divided into segments by the radii 43 to designate time periods, and the top of the time table is provided with a suitable mark 44 to enable lining up the chart-for starting and stopping positions in time. Drawn on the graph 42 is the guide line 45 which may be in the form of a line drawn in India or other electrically conductive ink, or in the form of a conductive inlay or strip. The line 45 is wide enough so that both of the points 25 and 21 can rest on the line together.

For operating the described mechanism for controlling a machine, the reversible motor 8 is connected as shown in Figure 8 to a manual reversing switch 46 which has the blade mountings 41 and 48 connecting to corresponding conductive armatures 49 and 50 which are operated by a relay magnet which is energized from the vacuum tube plate circuit cut on and off by the contact of the contact points with the line 45 on the chart. The armatures 49 and 50 severally disposed between armature contacts 52 and 53 and 54 and 55, respectively. The contacts 53 and 54 are connected together and are connected by a wire 51 with one side of the 110 volt A. C. or D. C. line as indicated by the numeral 58, with the field 55 of the reversible motor connected therein. The remaining side 60 of the power line is connected to the armature contact 52 and by means of the jumper 6| to the armature contact 55.

The chart 2! may be ordinary paper ruled in ink or printed. Only the control line or curve 45 is drawn in conducting ink. It will be noted that the contact points 25 and 21 can be moved to any place on the chart by operation of the turntable 30 by means of phonograph motor, clockworks, or similar operating mechanism, and/or by operation of the block I 9 by means of the motor 8.

By way of illustrating employment of the device of the invention, let it be supposed that it is desired to provide for varying current output from an unattended and isolated hydroelectric station for a certain period of twenty-four hours, the chart 2! is divided into 24 equal parts rel resenting hours and to arrange that the turntable 30 turn at the rate of one revolution in twenty-four hours. The pinion 9 on the shaft of motor 8 is connected to the control apparatus which is to be operated over the twenty-four hour period, in accordance with the conductive line or curve 45 on the chart, to produce the following variations in current output:

Time

csocaccmw i The load curve is plotted on the chart in terms of kilowatts and hours and drawn with conductive ink.

It is to be noted that since the points 25 and 21 are mounted on block l9 which is connected to the motor shaft through the lead-screw l2 and the gears l0 and II, a certain definite number of revolutions of the motor 8 will be required to move the points a given distance along a radius of the chart. For example, supposing the motor shaft is in zero position when the points are at the zero reading of load on the chart, then it will require a given number of revolutions of the motor shaft to move the points 25 and 21 to the load reading on the chart. Let this number of revolutions be designated by the letter n.

The electric line follower does only one thing. It keeps the points on the edge of the line or curve 45 as the curve moves under them. This is done by the circuit which controls the direction of rotation of the motor 0.

Assuming that it is midnight and the device has been placed in operation and the chart is rotating, so that the line 45 is sliding under the points 26 and 21, the motor shaft is rocking a part of a revolution in each direction, pushing both of the points onto the line 45 and then reversing until one point comes off the line. The angular position of the motor shaft is at 0.3 n revolution above zero, since zero revolutions is assumed to be the value when the points are at zero load on the chart and n revolutions is the value when the points are at 1000 kw. on the chart. The line now is at 300 kw., hence the 0.3 n revolution. Nothing new happens until 1 oclock in the morning when the curve shows that a drop from 300 kw. to 250 kw. is desired. Since the motor keeps the points on the curve, it must turn 0.05 n revolution to push them to the new position of the curve, making the motor stop when the 0.05 n revolution has been made, and start rocking as explained above. This condition remains until 2 oclock. The motor then makes another 0.05 n. revolution in the same direction as at 1 oclock in order to keep the points on the curve. No further revolutions of the motor are made until 3 o'clock when the motor makes 0.01 n revolution to keep the oints on the line at kw., on the curve, or 0.190 n revolution above zero. At 4 oclock the curve rises from 190 kw. to 420 kw., so that the motor shaft must make 0.230 n revolution in the opposite direction to keep the points on the line.

It will be noticed that any load desired corresponds to a given number of revolutions of the motor shai't from the zero position. This means that the motor shaft can be geared to the control apparatus of the power plant with the following results:

Supposing that the plant ha a total capacity of 1000 kw., and with the gates wide open, it gencrates this amount. With the gates half open, it generates half load or 500 kw., and so on. By gearing the motor 8 to the gate controls through a suitable coupling, it can be arranged that at n revolutions of the motor shaft the gates are wide open, at 0.5 n revolution the gates are half open etc. This makes it possible to control the future operation of the plant by means of a curve drawn on chart 29. The purpose of the pinion gear 9 on the motor shaft is, therefcre, to couple the controls of the machine to be operated to the motor of the electric line follower. This is, in effect, coupling the controls of the machine to the curve on the chart.

In operating the device, the prepared chart is placed on the turntable 30 by grasping the support I4 and lifting. The entire lead-screw and motor mechanism will pivot on hinge 1, so it will be out of the way, making it possible to place the chart on the turntable. The chart is then turned the turntable 56 is then wound.

The points 26 and 21 on block l9 will be either inside the curve 45 or outside of it when the lead-screw mechanism is lowered into place. Th device is then turned on" electrically, power being supplied to the electric circuit.

Assuming that. after the chart has been placed on the turntable and the lead-screw mechanism has been lowered into place, the points come to rest inside the curve, that is, at a point somewhere between the curve and the center the chart. When the power is turned on, the leadscrew driven by motor 6 will either push the points toward the center of the chart or pull them out toward the curve, depending on the position of the switch 46, Figure 8.

It, at this time, the motor 6 pushes the points toward the center of the chart, it shows that switch 46 is in the position for making the points follow the outside edge of the curve. By outside edge is meant theedge of conductive ink lin 45 which is farthest from the center of the chart.

The operatormust now decide which edge of the linked curve or line he desires the points to follow. If he wishes to hav them follow the outside edge, he shuts off the power and turns gear Ill by hand until the points are between the curve and the edge of the chart. He then turns on the power and the device is in operation.

Should the operator decide to have the points follow the inside edge of the line, and conditions are as described above (that on test application of power the Points are between the curve and the center of the chart and try to go toward the center), he simply throws the switch 46 to its other position, turns on the power, and the device is in operation, following the inside edge of the curve.

Supposing that in adjusting the device for operation the points have come down at a point outside of the curve 45, that at a point between the curve and the outer edge 01' the chart, on test application of power the points will either move toward the curve or away from it.

If the points move toward the curve (in this case toward the center of the chart), it means that switch 46 is set to make them follow the outside edge of the conductive curve. If this is what the operator desires, he leaves the power on. The device is operating as he wishes.

If the points move away from the curve (in this case, away from the center of the chart), it means that switch 46 is set to make them follow the inside edge of the line. If the operator wants them to follow the outside edge, he simply throws the switch 46 toits other position. If he wants them to follow the inside edge of the curve, he leaves the switch 46 as it is and moves the points by hand across the curve to some place between it and the center of the chart, and then turns on the power.

It is evident from the foregoing that the device will do one 0! two things, depending on the position of the switch 46, namely:

(1) Follow the outside edge of the line 45, or

(2) Follow the inside edge of the line 45.

The operator, must arrange the switch 46 and manually move the points by means of the leadscrew so that they will move toward the curve when the power is turned on. They will then automatically find the line and follow it.

As explained before, there are no critical circult constants, the following conditions being sufficient for the operating circuit shown in Figure 3 of the drawings: (1) The fC" voltage must be high enough to block the vacuum tube 62, that is, cut oil the plate current when both points 26 and 21 are on the ink line 45. (2) The vacuum tube 62 and the "B voltage must be chosen to fit the requirements of the relay 5|.

No heater connections have been shown for the vacuum tube 62, and batteries are shown for simplicity in tracing the circuit and describing its operation. It will be understood that any of the usual methods of energizing the circuit such -as transformers and rectifier, may be used. l

Startingwith the manual reversing switch 46, X

in the motor armature circuit in the position shown in dotted lines, this connects point 41 to point 46 and point 46 to the other side of the motor armature, and assuming that at the instant of starting, both points 26 and 21 are resting on the conductive line 45 as shown in Figure 8, it can be seen that the grid of the tube 62 is at a high negative potential with respect to the cathode. This particular circuit consists of the cathode of the tube 62, and the conductor 63 to point 26, the I conductive line 45 from point 26 to point 21, the wire 64 to the positive side of the 0" battery, the 0" battery, the wire 65 to the grid of the tube. A negligible amount of current will also flow through the resistance 66 which is placed between the grid and cathode, but this is immaterial at this time.

With the vacuum tube grid at a high negative potential as described above, no current can flow from the cathode to the plate. The tube is blocked." Under these conditions, no current is flowing in an part of the plate circuit which consists of the vacuum tube 62 (cathode-toplate), the conductor 61 from the plate to relay coil 5|, the relay coil 5|, the conductor 66 from the coil to the positive side of the B battery, the- B battery, and the conductor 69 from the negative side of the B battery back to the cathode of the vacuum tube.

With no current flowing in the plate circuit as described above, there is no current flowing in the winding 5| of the relay, since it is a part of the circuit. There is no attraction oi the armatures 49 and 50, and they remain in the position shown.

Under the above conditions, the current in the motor circuit takes the following path: Power line to conductor 60 to conductor 6|, to relay contact 55, to relay armature 50, through the conductor 10 between relay armature 55 and point 41 on the manual reversing switch 46, to point 41 on the manual reversing switch. With the switch 46 in the position shown, current will flow from point 41 to point 46, then to the motor armature 6, through it, back to the manual reversing switch to armature 49 of the relay. Since the relay coil 5| is demagnetized, the relay armature is in the position shown, so that the current will flow from armature 49 to contact 53 and conductor 51 to the motor field 59, through it and back to the power line conductor 56.

In this case at a given time, current is flowing upwardly through the motor field 59 and from left to right in motor armature 6. The direction of motor rotation will be such as to move the points 26 and 21 to either the right or left. The direction of point motion is immaterial in this description since it can be changed at will by means of the manual reversing switch which reverses the motor armature connections but does not aifect the field connections of the motor. Assuming that the operator has decided to have the points 26 and 2! follow the right-hand edge of the line 45, then the above conditions will cause the motor to rotate in the direction which will pull the points 26 and 21 toward the right.

The motor will continue to run in this direction until it has pulled point 25 oil? of the line 45. It can be seen that point 25 will leave the line 45 before point 21. In practice, the motor will reverse when noint 25 leaves the line, but point 21 will still be on the line. The reason for reversal of the motor, and the means whereby it is produced are set forth below.

Assuming that the motor has moved the points to the right until point 25 is off the line 45, but point 21 is still on the line, the following changes taking place:

There is no longer a complete grid circuit because the point 26 is no longer on the conducting line 45. battery is removed as far as use is concerned because its circuit is open between point 25 and point 21. The negative cha ge which C battery had maintained on the {5541'} of the vacuum tube 52 now leaks off through the 10 megohm resistance 55, bringing the grid and cathode to approximately the same potential.

Removal of the negative charge on its grid allows the vacuum tube 62 to conduct current and the 3" battery circuit is now completed through the vacuum tube and current flows around the loop which also includes the winding of the relay 5|. Current in the relay winding causes it to attract the armatures 49 and 50, pulling them away from contacts 53 and 55 and engaging them instead with contacts 52 and 54, respectively.

The above relay operation reverses the motor since then current flows from the power line down through conductor 50 as before, but can on longer reach armature 50 through contact 55 because the armature has been attracted to the relay magnet 5|, but instead, the current flows to armature 49 through contact 52 which has been closed by the relay magnet 5|. From armature 49. the current flows to point 45 on the manual reversing switch. The position of this switch not having been changed, the current flows through it to the right hand side of the motor armature 5, through it and back to point 41 on the manual reversing switch, through the switch to point 41 and then to armature 55, contact 54, conductor 51, motor field 59, conductor 55 and back to the power line. It will be noticed that the current flows upwardly through the motor field in both cases, and that when both of the points 25 and 21 are on the conductive line 45 current flows from left to right in the motor armature, and that when point 26 is off the line 45, the current fiows from right to left in the motor armature. As a result, the motor will run in one direction when both points are on the line 45, and in the opposite direction when one point comes off the line 45. The direction of rotation of the motor is continually changing since it must be running at all times. The direction of rotation at a given instant is determined by the position of the points 26 and 2! with respect to the line 45 at that instant.

Extreme conditions of operation The action of the device under the most extreme conditions possible can be understood by reference to the enclosed Figures 9, and 11.

In Figure 9, the line 45, is moving at a right angle to the lead screw l2, so that the motion of the line 45 and point motion are at right angles. The manual switch is set to make the points follow the lower edge of the line 45. Point 25 is off the line and point 21 is on the line. The motor pushes the points in the direction shown until both points are on the line. This reverses the motor, so that it pulls the points until point 25 is oil again. The process is repeated continuously until the line 45 changes direction.

In Figure 10, the line 45 makes an abrupt turn, so part of it lies parallel to the lead screw I2. The points follow the line 45 as in Figure 9 until the corner is reached. At this time the line 45 moves out from under point 21. The motor pushes the points as shown. Point 25 goes on the line, but point 21 being still oil, the circuit is still open and the motor continues pushing the points in the direction shown until the line changes direction. The line must sooner or later make a turn to the right, because no other kind of curve is encountered in practical work.

In Figure 11. the direction of the line 45 is abruptly changed to a position parallel to the lead scre l2, but opposite from the Figure 10.

The points were following the lower edge as in Figure 9 until the corner was reached. At this juncture, the line reached a position where both points rest on it. The circuit being thereby closed, the motor pulls the points downwardly until the line direction changes.

The connecting link mechanism between the electrical unit and the governor, shown in Figure 12, which controls the turbine gates, is through hydraulic servomotor unit while beginning with motor gear 5, motion is transmitted through gear train ll, 12 to rack on shaft 14 through bearing support 15, and the motiion of link 16 will center about the pivot at 55 transmitting such motion to piston rod 11, which operates as a control or relay valve in the cylinder.

The hydraulic unit will function as a controlling device. Oil from a high pressure pump. transmitted through pipe 15, will in a neutral position be trapped and no motion occurring. Pipes l5 and 55 are connected from extreme ends of control cylinder to oil pump reservoir existing under no pressure. It is evident from the above, that the valve piston and rod 11 will be free to move with very little resistance, and the power supplied from gear 5 will be suillcient to move this link-work. As piston with rod 11 moves in direction indicated by arrow X of any slight amount, high pressure oil will now to chamber from pipe 15 through oil pipe 52, transmitting pressure to large piston 55. Any required force can be attained by relative diameter of pistons 55, and 11. Motion of piston 55 will be transmitted to outer turbine gate ring 55 through link 55 to fixed ring 51, positioning the gates to the predetermined load requirement as plotted on the chart. The process of obtaining equilibrium will be by link 15 pivoting about 75 in its new position and gradually bringing piston and rod 11 to a neutral position, as in Figure 12, of no oil flow. Movement 01' rack and rod 14 in either direction will cause change in gate position through the hydraulic unit and will become neutralized in this position.

Should the operator wish the points to follow the upper instead of the lower edge of the line Having described the invention, what is claimed as new is:

1. An electric line follower comprising a chart having a conductive line formed thereon, means for supporting and moving the chart in a predetermined path and at a predetermined rate, a pair of spaced contactors to ride upon the chart and make electrical contact with said conductive line, electric motor means for moving said pair of contactors relative to the chart to follow along one edge of said conductive line, and coupling means on said electric motor means adapted to operate control means to cause operation of a machine in accordance with the arrangement of the conductive line on the chart.

2. An electric line follower comprising a chart having a conductive lineformed thereon, means for supporting and moving the chart in a predetermined path and at a predetermined rate, a pair of spaced contactors to ride upon the chart and make electrical contact with said conductive line, electric motor means for moving said pair of contactors relative to the chart to follow along one edge of said conductive line, and coupling means on said electric motor means adapted to operate control means to cause operation of a machine in accordance with the arrangement of the conductive line on the chart, a current source for energizing said electric motor means, said motor means being reversible, a manual reversing switch in circuit between said source and set motor means, said manual switch being arranged to be set to cause the contactors to continuously follow along one edge or the other of said conductor line.

3. A device of the character described comprising a base, a turntable mounted on the base. time controlled means for turning said turntable, an electric motor mounted on said base, said mOtOr having a shaft and coupling means thereon for connection to drive control apparatus, a normally horizontal assembly hinged at one end P to said base and having its free end portion overhanging the turntable when in horizontal position, said assembly being adapted to be swung upwardly away from said turntable, a chart on said turntable having a conductive line, said chart being adapted to be placed and removed while said assembly is in an elevated position. a longitudinal feed screw on said assembly, an operating connection between the shaft of the motor and said feed screw, a carrier slidably mounted on said assembly for movement along the carrier and across the chart in either direction, said carrier being threaded on said screw, a pair of laterally spaced contactors depending from said carrier for engagement with the chart and for electrical contact with the conductive line thereon, and electrical means affected by the contact of at least one of said contactors with an edge of said conductive line on the chart whereby said motor means is automatically operated in forward and reverse directions to maintain or return the contactors into contact with said conductive line on the chart during the revolution of the turntable.

ARTHUR R. McCOURT.

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