US1790681A

US1790681A - System of motor contbol

Info

Publication number: US1790681A
Authority: US
Publication date: 1931-02-03
Anticipated expiration: 1948-02-03

Description

H. L. SMITH SYSTEM OF MOTOR CONTROL Feb. 3, 1931.

Filed Dec. 5, 1928 Inventor Z I Hugh Smith,

Patented Feb. 3, 1931 UNITED TATE'S vHUGH L. SMITH, OF SCHENEUPADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK SYSTEM OF MOTOR CONTROL Application flledDecember 5, 1928.' Serial No. 823,834.

Fhis invention relates to the control of electric motors and moreparticularly to the control-of electric motors used for driving large units of machinery such, for example,

" as printing presses.

.In the operationof large printing presses it is necessary that a number of pressmen perform various duties and functions upon or about the press priorto the actual running .m and printing operations. Frequently it becomes necessary for a pressman to occupy a position close to the moving parts in or about the press in order to perform certain of his duties, such that serious harm might come 'to him if the press were started up while thus engaged. To prevent such an occurrence, a plurality of control stations are arranged about the pressin positions near or adjacent those'places where workmen most frequently have work or duties to perform.

A safe-run button or switch is usuallyprovidedat each of these control stations and 'these are connected. in a seriesjcircuit with the controlmechanism to the end that it shall 26 be impossible'to make the control mechanism effective to start the press-until all of these switches are closed and the series circuit established. It will beneali'zed, however," that the protection afforded by anymanually operated safety device is at best uncertain 'because of the fact that it isdependent-upon the care and thoughtfulness of the operative, or upon 'his decision either to exercise or not to exercise the option of operating the safety device.

extricate himself from his position of danger.

An object of invention is the provision of a safety means that will materially reduce the danger to which operatives and attendants of-large machines are subjected.

Another object is the provision of safety means that can be used in conjunction with provision of a system in conjunction with the motor control circuits togive a suitable 1 warning signal at the instant that a control switch is closed to start the driving motor at a time whenthe control apparatus-is entirely deenergized and in its pro-starting position, and also to delay the starting'of the driving 7 motor for a predetermined interval of time after the closing of thecontrol buttonand the giving of the signal, suflicienttoenable all workers in a position of danger .to get clear of the apparatus. 00

In the operation of printing presses it .is often necessary when platingup or adjustingthe plates on the cylinders to move the cylinders a fraction of a turn. This operation is knownas jogging or inching. Since this operation is resorted to so frequently,.it is not desirable-that a time delay shouldlbeinterposedbetween each closing ofthe jog switch and the starting ofthe motor-because much valuable time would be 76 wasted. However, it is desirable, that all engaged in work inthe proximity of the press should be apprised of this condition and put upon notice that the press is likely tobe started p'eremptorily without the usual warning signal and time delay.

It is a stillfurther object of my invention to provide a signal system that will permit of the jogging operation afterthe press has once been startednp and the usual warning as signal and timedelay given, without interposing further time delays between subse quent closings of the jog switch and the starting of the motor, but which will give a second warning signalto apprise .the press-1. man and operatives about the press that it maybe started-up at any instant.

For a better understanding of my inventionreference should be had to-the following specification and the accompanying drawing, thesingle figure of'which is a diagrammatical representation of one embodiment of'the invention.

In carrying outrmy invention in one form, a printing press or any other large machine escapement gear train 79 driven by unit (not shown) is adapted to be driven by a suitable driving means, such as the electric motor 10 which is arran ed to be supplier from a source of electric power 11. A line contactor 12 serves to establish electrical connections between the source of power 11 and the armature of the motor 19 through the starting rheostat 13. The starting, stopping, and jogging operations of the motorare controlled from a control station 14-. In order not to complicate the drawing unduly, l have shown but two control stations but those skilled in the art will appreciate that as many control stations as are desired may be provided at different positions about the press.

At each control station a plurality of control buttons or switches are provided. A safe-run button 15 normally biased to the closed position serves, when actuated to the open position, to deenergize the main control.

I circuit and to make it impossible to start the motorfroin any control station. Thus it will be seen that the safe-run buttons at all control stations must be in the closed position before the motor 10 can be started. The starting of the motor for the jogging operation is controlled by thenormally open jog button 16. Establishment of rumiing connections for the motor is controlled by the normally open fast button 17. Actual closing of the line contactor 12 to start the motor is controlled by either the jog relay 18 or the fast relay 19 when actuated to the closed position in response to" the closing of the corresponding control button. lhe normally closed stop button 39 serves when depressed to the open position to deenergize the control circuits for the motor and to effect stopping of the motor and return of the control apparatus to its initial or pie-starting position.

To prevent the line contactor 12 from being closed until a predetermined interval of time has elapsed after the energization of either the jog or the fast relays, a suitable definite time delay device 20 is provided which is set into operation when either the fast or the jog relay is operated. A spring when placed under compression by energization of coil 23 serves to actuate arm 7 6 and the gear sector 'Z'Zcarried thereby in a clockwise direction about the pivot 78. An the sector 77 serves to retard the motion and prevent the arm from engaging lever 41:? until arm 7 6 has reached its limit of travel, thereby introducing a time delay in the closing of contacts 49, the purpose of which will be more fully explained hereinafter. Auxiliary movable and

stationary contact members

21 and 22 respectively cooperate to provide a self-holding circuit for the energizing'coil 93 of the time delay device 20 so that a time de lay will not be interposed between subsequent operations of the jog button and the actual starting of the motor. Operation of either of the fast or the jog buttons at a time when the press has been shut down and all apparatus is in its normal or pre-starting position causes the warning gong 2a to be sounded to give notice to all engaged about the press that it is about to be started up. Any other kind of suitable signal means, such for example, as a. visual signal may be employed in place of the audible signal gong 2%.

Contacts

25, 26 in the signal circuit are adapted to be interrupted by the time delay device 20 at the expiration of the time interval, so that no further warning signal can be given by the gong as long as the time delay device 20 remains operated. To forewarn all operatives when the press is at rest between jogging operations that it is likely to be restarted without further warning from the signal gong, red warning'lights 26a are provided which are arranged to burn whenever the time delay device 20 is operated and the motor is at rest, i. e., between jogging operations of the motor. A still further precaution against danger in the interval between jogging operaticns is afloroed by the provision of a flashing" mechanism 27 to flash the regular press illuminating lamps or any other lamps which may be provided for the purpose, at recurring intervals during this period. A flashing signal has been found to be extremely effective in conveying a warning. The circuit of the illuminating lamps 28 is adapted to be interrupted by the flasher relay 29 when suitable potential exists at the termin 30, 31. Operation of the flasher relay 29 to open the illuminating lamp circuit causes the time relay to function to reclose the circuit. The use of the flashing mechanism. :27

to flash the illuminating lamps is purely ops tional and may be dispensed with. On the other hand, the red warning lamps 26a may be omitted and the flashing mechanism 2'? used in their place to provide the warning signal.

The amount of resistance in the armature circuit of the mainmotor 10 and the speed of the motor is determined by the position of the rheostat arm 33 which is rotated by the pilot motor 34:. hen the fast button 17 is maintained in closed position after the operation of the time delay device 20, the rotation of pilot motor to short circuit resistance in the armature circuit of the main motor is controlled by contactor 35, while rotation in the reverse direction to rcinsert the resistance is controlled. by contactor 36. Limit switches 37 and 38 are provided to stop the pilot motor and to prevent rotation of the arm 33 past either extremity of its preordain-ed travel.

Assume now that the press is entirely shut down with all the parts in theirnormal or prestarting positions, as shown inthe drawing. If it be desired to start up the press for jogging to enable plates to be fastened upon the cylinders, all the safe-run buttons at the various control stations must first be closed. Depression of a jog button 16 momentarily will cause the coil of jog relay 18 to be energized over a circuit extend ing from the conductor L of the source of supply 11, through contacts of safe-run buttons 15, contacts of stop buttons 39, contacts of jog button 16, coil of relay 18,

conductors

40 and 41, to the opposite side L, of the source of supply. Relay 18 now picks up closing its contacts 42 and 43 and a warning signal indicating that the press is about to be started isgiven. by warning gong 24 which is energized over the following circuit: L safe-run button 15, stop button 39,

conductors

44 and 45, contacts 43 of relay 1'8, conductor 46,

contacts

25 and 26, gong 24,

conductors

40, 41 and L Closing of the contacts 43 also establishes a circuit through the energizing coil 23 of the time delay device 20 to

conductors

40, 41 and L,, causing time delay device 20 to commence its operation. The movable contact member 21 is moved into engagement with the stationary contact members 22 immediately upon energization of coil 23 to short circuit contacts 43 and establish a self-holding circuit for coil 23. After the elapse of the definite interval of time required for the operation of time delay device 20, lever arm 47 moves contact arm 25 out of engagement with contacts 26 stopping the warning gong 24 and in the same -movement moves the contact member 48 into engagement with the station ary contact members 49. Should the jog button 16 be released at any time after having been depressed, relay 18 would fall down, but time delay device 20 would remain held The press is now in condition to be started up instantaneously by depression of buttons 16 or 17 without any further signal being given by gong 24, and warning of this con dition is given by the red warning lamps 26a which after, operation of the time'delay device 20 and up until the time when either .jog button 16, or fast button 17 is depressed are included in a circuit extending from L through buttons 15 and 39,

conductors

44, and 50, contacts '21 and 22,

' co-udi'actor 46, contacts 48 and 49, conductor 51, warning lamps 26a, conductor '52, upper auxiliary contacts 53 of line contactor 12, conductors 54, 41 'to L, Whenever a potential exists at the terminals of the warning lamp 26a, the same potential will exist at the terminals 30, 31 and the flashing mechanism 27 will be set into operation to flash the press illuminating lamps 28..

The operation of flashing mechanism 27 will be explained at this point The regular press illuminating lamps 28 are supplied from any suitable source of power 100 through the normally closed contacts 101 of flasher relay 29 when the press is running or when it is entirely shut down. When the red warning lamps 26a burn between jogging operations, a potential exists at the terminals 30, 31 of the flashing mechanism 27. The coil. of flasher relay 29 is then energized over the circuit terminal 30, conductor 102, coil of relay 29, conductor 103, con tacts 104. conductor 106, and terminal 31. Flasher relay 29 picks up, opening contacts 101 and extinguishing the illuminating lamps 28. In this movement relay 29 also closes its main Contact 107 to establish circuitsfor the relay coil 108 and motor 109 of time relay 112, relay coil 108 and coil of motor'109 in parallel,

conductors

113, 102, and terminal 30., Relay coil'108 whenenergized closes normally open contacts 114' energizing the coil of relay 105 from terminal 31. conductor 106,

contacts

110 and 114, coil of relay 105 to terminal 30. Relay 105 picks up opening its contacts 104, and energizing circuit of flasher relay 29 is opened permitting contacts 101 to close and reestablish circuit for the illuminating lamps 28, thus impartinga flicker or flash to the lamps. The opening of contacts 107 does not disturb the circuits for the relay coil 108 and. motor 109,since these circuits are maintained closed by the contacts 115 of relay 105. After a definite time, contacts 110 are opened by the motor 109 and relay 105 is deenergized, permitting contacts 115 to open and deenergize the relay 108 and motor 109, and allowing the mechanism of time relay 32 to reset. Those skilled in the art will understand that this operation will be repeated at regular intervals so long as potential existsat the terminals 30, 31. In other words, the illuminating lamps 28 will be flickered at regular intervals whenever warning lamps 2611 are burning.

If the 'og button be again depressed, relay 18 will be energized over the same circuit as before and will close its contacts 42.,to energize the coil of starting contactor 12, contacts 48 and 49 having been previously closed by the time element device; the circuit being from L through buttons 15 and39,

conductors

44, 45 and 50,

contacts

22, 21, contacts 48, 49, conductors 51, 56, contact 42, conductor 57, interlock contacts 58 on rheostat arm 33, conductor 59, coil of line contactor 12 and conductor 60 to L tactor 12 will now pick up closing its main contacts 61 to connect motor 10 with the line over the following circuit :-L contact 61, motor armature 10, rheostat 13 to L Simultaneously, with the closing of the main contacts 61 the line contactor opens its auxiliary contacts 53 to extinguish the warning lamps 26a and to stop the flashing of the Line coni 1 illuminating lamps 28. The motor 10 will now turn over very slowly becausethe full resistance of. the rheostat is included in the armature circuit, and it will continue t over only so long as the jog button 16 is maintained depressed. Should the button 16 be released, relay 18 will fall down opening the energizing circuit of the line contactor 12 which will also fall down opening its main contacts (51 to interrupt the met circuit and closing its auxiliary contacts 53't-o cause toe warnr g lamp 2% to burn again and the illuminating lamps 28 to be flashed. Ba depression of the button 16 would immediately cause relay 18 to pick up and close the control. circuit to the line contactor as be fore to start the motor and extinguish the signal lamps. This jogging operation may be repeated as often as is desired.

Assume that in this condition of the apparatus with the time delay device 20 in its operated position and the signal lamps 26a burning, it is now desired to run the press at full speed. The fast button 17' is depressed and the coil of fast relay 19 will be energized over a circuit that may readily be traced. Relay 19 will now pick up closing its main contacts 62 to establish a circuit for the energizing coil of contactor 6. and also for the energizing coil of fast contactor the circuit for the former being traced from L through buttons 15 and 39,

conductors

44, 15 and 50,

contacts

21, 22, conductor 46, contacts 18, 419, conductor 51, contacts 62, conductor 63, conductor '2 3, coil of contactor 67, conductor 60, to L and the latter being traced over the same circuit as far as conductor 7 3, and thence through limit switch 37, conductor 6 coil of fast contactor 35, conductor 65, to L Gontactor 6'? now picks up closing its main contacts 58 connecting' the coil of line contactor 12 with L and L causing the line contactor 12 to close ont-acts (31 to connect the armature of the main motor 10 across L and L through the rheostat 13. Simultaneously with the closing of main contacts 68 of cont-actor 67, the auxiliary contact is closed to provide the following self-holding circuit for the coil of (ii, L buttons 15 and 39, conductor lat, auxiliary contacts (39, coil of relay 6?, con uctor (30, L lilo-tor 10 now begins to to slowly.

iheenergization of the coil of fast contactor 35 causes it to close its mam contacts (36 to connect the pilot motor 34- across L and L and'pilot motor will now rotate the rheostat arm 33 in a counter-clockwise direction to short circuit resistance sections of rheostat 13 to speed up the main motor. i i hcn the rotation of main motor 10 has reached the desired speed, the fast button 14c may be released, thereby permitting relay 19 to open its main contacts 62 and deenergize contactor 35 which will now open its main contacts 66 disconnecting pilot motor 34 from the line and stopping the rotationof the rheostat arm 33. The main motor 10 will run at this desired speed until stop button 39 is depressed to open the control circuit to the coil of relay 67 which will then open its main contact 68 and interrupt the holding circuit previously described for the line contactor 12. The control circuit for coil 23 of time delay device 20 will also he opened when stop button 29 is depressed and time delay device will be returned to its initial position. When relay 6'? releases, it closes its lower main contact 70 to establish a circuit for the. coil of contactor 36 running from L through contact 70, conductor 71. limit switch 38. conductor to L Contactor 36 willthen be picked up and will close its upper contact 7 2 to connect the pilot motor. with L, and L so that current will flow through its armature in a direction the reverse of that reviouslv described, causing the motor to rotate in the reverse direction and return the rheostat arm 33 to initial position. After the arm 33 reaches initial po sition, it opens limit switch 38 thereby deenergizing the coil of contactor 36 and allowing the contactor to fall down to disconnect pilot motor 34: from the line and to connect its armature with the breaking" resistors r it; through the lower main contact '24-. The various elements are now in their normal or prestarting position.

Those who are skilled in the art will appreciate from the foregoing description that the fast button maybe employed to initiate the entire starting operation from rest when the parts are all in their normal posi tions and in this case the operation is substantially the same as when the jog button is used with the exception that the func tions of initiating the operation of the time delay device 20 and sounding the warning gong 2 1 during the time delay interval is controlled by the auxiliary contacts 62a of the fast relay 19 instead of being controlled by the auxiliary contacts 43 of relay 18. They remaining operations are exactly the same as those previously described.

I have described my improved signaling system as operating in conjunction with the starting, jogging, and running operations of a printing press. Those skilled in the art, however, will appreciate that it is equally applicable to any large unit of machinery arranged for similar or analogous operations.

"While I have described my invention as embodied in concrete form and operating in a specific manner in accordance with the pro visions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A system of motor control comprising control means for said motor and means dependent upon the operation of said control means for preventing operation of said motor until after a predetermined time interval, after which said motor may be operated by saidcontrol means.

2. A system of motor control comprisin manually operated means for starting and stopping the motor, a time delay device set in operation to prevent starting the motor for a predetermined time interval after initial operation of said manually operated means and for rendering said manually operated means effective at the expiration of said time interval to start the motor.

3. In a system for the control of electric motors, manually operated means for starting and stopping the motor, a time delay device controlled thereby to delaythe starting of the motor for a predetermined interval of time after operation of said manually operated means to start the motor and 'to give direct control for starting said motor to the manually operated means at the expiration of said time interval.

41. In a system for the control of electric motors the combination which comprises an electric motor, manually operated push buttons for controllin the starting of said motor and a line switcl i for said motor controlled thereby, a time delay device set into operation when one of said manually operated push buttons is first depressed to start the motor to prevent the closing of said line switch for a predetermined time interval and to cause said line switch to be closed thereafter when said manually operated means is depressed a second time.

5. In an electric motor control system,a line contact for controlling the power circuit of said motor, having its energizing winding included in a normally open circuit in series relationship with a normally open contact, manually operated switch means for starting and stopping the motor and a time delay device controlled thereby to prevent closing of the line contactor for a predetermined time interval after initial operation thereof to start the motor, and to close said normally open contacts at the expiration of said time interval partially to close said electric circuit whereby said manually operated swltch means is rendered effective, when operated a second time, to energize said line contactor and start said motor.

6. A controller for electric motors comprising in combination a control device for starting the motor, means including a time delay device controlled by said control device for delaying the starting of the motor for a the like, the combination which comprises manually operated means for controlling the starting of the motor, a timevdelay device for delaying the starting of the motor for a predetermined interval of time after the operation of said manually operated means, signalling means controlled by said manually operated means for giving a warning signal during said predetermined interval of time, means responsive to operation of said time dolay device for terminating the operation. of

said signalling means and rendering said manually operated means effective to start the motor at the expiration of said time interval, and means for rendering said time delay device ineffective to delay the starting of the.

motor upon repeated operation of said manuallyoperated means.

8. In a motor controller, the combination with electromagnetic switching means for starting and stopping the motor of a manual ly operated control element therefor to effect starting for jogging, means including a time element device set in operation in response-to operation of said control element for delaying the starting of the motor for a I predetermined interval of time after an initial operation of said control element, means responsive to initial operation of said control element for giving a warning signal during said timeinterval, means responsive to operation of said time element device for rendering said signalling means ineffective and for rendering said control element effective to start the motor at the expiration of said time interval, and means for rendering said time element device ineffective to interpose a time delay upon subsequent operations of said normally operated control element.

9. In a system for controlling the operation of motor driven printing presses and the like, means including a manually operable control element and a line contactor having its energizing winding connected in a normally open circuit and controlled thereby for connecting the motor with a source of supply,

in operation in response toinitial operation of said control element for delaying the closing of said circuit for a predetermined interval of time thereafter and for partially closing said circuit at the expiration of said time interval, means responsive to initial operation of said control element for giving a warning signal during said time interval, and means including a holding circuit established means including a time element device set in the operated position of said time element device for rendering said time element device ineffective to delay the starting of the motor upon subsequent operation of said control element.

10. In a system for the control of electrically driven printing presses, a manually operated control element for efiecting starting for jogging, signaling means rendered effective by the operation of said control element to give a warning signal, a time delay device controlled by said control element for delaying the starting a predetermined interval of time after the operation of said control elementmechanism controlled by said time delay device for rendering said signaling means ineffective at the expiration of said time interval, means for retaining said time delay device in its operated position, and a I second signaling means rendered effective by the time delay deviceto give a second Warning signal When and if the control element is released after the operation ot-said time delay device. In witness whereof I have hereunto set my hand this 4th day of December, 1928.

HUGH L. SMITH.