US2123058A - Control device and system - Google Patents

Description

y 1938. T. l. MASLIN ET AL 2,123,058

CONTROL DEVICE AND SYSTEM Filed June 26, 1955 Figl. Fig.2.

START F Inventors: Thomas ,I. Masl'm,

Roy N. Thomas,

by d

Thei Attorney.

Patented July 5, 1938 CONTROL DEVICE AND SYSTEM Thomas I. Maslin,

Bloomfield, and Roy N.

Thomas, East Orange, N. J., assignors to General Electric Company, a corporation of New York Application June 26, 1935, Serial No. 28,470

8 Claims.

Our invention relates to control systems for electric motors, more particularly to control devices and systems for selectively energizing electric motors either for continuous operation or for inching or jogging operation, and has for an object the provision of a simple and reliable control device and system of this character.

It has heretofore been proposed to provide the driving motors for printing presses and similar 10 apparatus with control systems, including control devices for providing inching or jogging operation during the make ready period and for providing continuous operation of the driving motors thereafter. It has also been proposed in connection with such apparatus to provide a push button control station for accomplishing the jogging operation. In such previous systems, one or more push buttons have been provided with means for selectively locking the push button in one posi- 0 tion or another by some preliminary operation,

such as rotating the button or adjusting a looking attachment.

It will be apparent that when such a preliminary operation is necessary to ensure jogging of the driving motors, considerable reliance is placed upon the person operating the push button and consequently, there is considerable danger to other persons working around the apparatus if the operator forgets to make the preliminary adjustment before operating the push button. For example, if persons working around the machine expect only the jogging operation and the operator neglects to make the preliminary adjustment, the resulting continuous operation of the apparatus may endanger the safety of the persons who expected only a jogging operation.

The driving motors for such apparatus are usually controlled by an electroresponsive starting switch having interlock contacts for establishing a holding or maintaining circuit when the switch is energized, and it has been proposed to overcome the above objection to some.

extent by providing separate start and jog buttons, the jog button being normally inaccessible to the operator and being provided with manually operable means for rendering it accessible. Both the jog and the start button are arranged to energize the starting switch directly, and the means for rendering the jog button accessible is effective when operated to interrupt the holding circuit. Although such arrangements do not depend upon the skill of the operator for reliability of operation, much is yet to be desired in a push button station by means of which jogging operation may be accomplished without resort to a preliminary operation for safety purposes and without depending upon the skill of the" operator. Accordingly, it is a further object of our invention to provide a control system for accomplishing jogging operation of an electric motor, which system is provided with a jog button which requires no preliminary operation by the operator,

which is automatically held in jogging position gizing circuit and a maintaining circuit, which motor-starting switch is controlled by a push button station having a separate jog button and a separate start button. The jog button is provided with a pair of closed contacts common to both the energizing circuit and the maintaining circuit and with a pair of normally open contacts for establishing an independent energizing circuit when the jog button is depressed. Means are also provided which are automatically responsive to depression of the jog button for preventing the jog button from returning to its normal position to close the maintaining circuit while permitting the jog button to be moved to close and open the normally open contacts to energize and de-energize'the starting switch as many times as desired. Means are also provided for releasing the jog button for movement to its normal position when it is desired to operate the driving motors continuously.

For a more complete understanding of our invention, reference should now be had to the drawing in which Fig. l is a plan view of a push button control station provided with a jog button embodying our invention; Fig. 2 is an elevational view, partly in section, of the control station shown in Fig. 1; Fig. 3 is a fragmentary sectional view showing the jog button in its latched posi- Thomas I. Maslin.

As shown, this push button switch comprises a base formed of molded insulating material having an open slot I2 at one side thereof. Secured to the base II on opposite sides of the slot I2 are pairs of spaced stationary contacts I3 and I4 provided respectively with suitable terminal screws I5 and IE, only one contact of each pair being shown in the drawing.

Mounted for movement between the pairs of stationary contacts I3 and I4 is a bridging contact member I1 carried by a reciprocal operating rod I8 slidably journaled in the base I I, the upper end of the rod I8 carrying the push button I9. The bridging contact I1 is of irregular shape for a purpose fully described in the above patent and is resiliently held against a collar 20 formed on the rod I8 by a compression spring 2|. Surrounding the operating rod I8 is a biasing spring 22 the opposite ends of which respectively engage the insulating base II and the push button I9, the spring 22 being considerably stronger than the spring 2| and serving to bias the push button I9 and the movable contact I1 to the position shown in Fig. 2.

As shown, the push button I9 is provided with a flange or shoulder 23 arranged to co-operate with a. latch 24 secured to an L,-shaped finger 25 pivotally mounted on a pin 28 with the end of the member 25 extending through an aperture 21 in the casing I0 adjacent a guard ring 28 which surrounds the push button I9. The pin 26 is rigidly mounted on a bracket 29 which is secured to the casing I0, and a spring 38 surrounding the pin 26 normally biases the latch 24 into engagement with the circumferential surface of the flange 23 as shown in Fig. 2.

Referring now to Fig. 3, it will be apparent that when the push button I9 is depressed, the latch 24 will be moved by the spring 30 to a position to engage a side of the shoulder 23 when the push button is released, to hold the push button and the movable contact I1 in the intermediate position there shown. It will be apparent now that the push button may be depressed as many times as desired so as to engage the movable contact I1 with the stationary contacts I4, during which movement the collar 20 is carried into an opening (not shown) in the base II, and that the movable contact I1 will be prevented from returning to its normal position; i. e., into engagement with the stationary contacts I3. When it is desired to release the push button I 9. the pivoted member 25 may be moved toward the guard ring 28 so as to compress the spring 38 and withdraw the latch 24, whereupon the push button I9 is moved to its normal position by the biasing spring 22.

It is believed that a complete understanding of our invention may now be had from a description of the operation of the control system shown in Fig. 4. As shown, the control system comprises an electroresponsive starting switch 3| for controlling the energization of an electric motor 32 which is connected to a suitable source of energy 33 through the conductors 34, 35, and 36. Energization of the operating winding 31 of the starting switch 3| is controlled by the control station shown in Figs. 1, 2, and 3, which includes. in addition to the jog button I9, a start button 38 having a pair of normally open contacts 39. In addition, the energizing circuit of the operating winding 31 may be provided with a stop button 48 having normally closed contacts, and the starting switch 3| is provided as shown with a pair 01 interlock contacts 4|.

When it is desired to operate the motor 32 continuously, the start button is depressed and an energizing circuit for the winding 31 is thereby established, which may be traced from the source of energy 33 through the conductors 36 and 42, the winding 31, the conductors 43, 44, and 45, the contacts 39 of the start button, the conductor 48, the normally closed contacts I3 of the jog button, the conductors 41 and 48, the stop button 40, and by way of the conductors 49 and to the source of energy 33. Operation of the starting switch 3| to its closed circuit position closes the interlock contacts 4| and establishes a maintaining circuit for the operating winding 31 which may be traced from the source of energy through the conductors 36 and 42, the operating winding 31, the conductors 43 and 58, the interlock contacts 4|, the conductor 5|, the normally closed contacts I3 of the jog button, the conductors 41 and 48, the stop button and by way of the conductors 49 and 35 to the source of energy 33. It will be apparent now that the motor will operate continuously until the maintaining circuit is interrupted to de-energize the winding 31.

If it is desired to inch or jog the motor before energizing the motor for continuous operation, the jogging or inching operation may be accomplished simply by depressing the jog button I9. As soon as the jog button is depressed, it will be apparent that the latch 24 will be operated by the spring 3|] as described in connection with Figs. 2 and 3, to prevent the jog button from returning to its normal position when the jog button is released. Operation of the jog button to its depressed position establishes an independent energizing circuit for the operating winding 31 of the starting switch 3|, which circuit may be traced from the source of energy through the conductors 38 and 42, the operating winding 31, the conductors 43, 44, and 52, the contacts I4 of the jog button, the conductors 53 and 48, the stop button 4|), and by way of the conductors 49 and 35 to the source of energy. Upon energization of the winding 31, the interlock contacts 4| will again close, but it will be apparent that the previously traced maintaining circuit will be only partially completed, since the normally closed contacts I3 of the jog button are now open. The jog button may now be operated between its depressed position and the intermediate position in which it is held by the latch 24 as many times as desired to energize the winding 31 and close the switch 3| to jog the motor, and there is no danger that the maintaining circuit will be established through the interlock contacts 4| to operate the motor continuously.

As soon as the desired preliminary operation or the equipment has been obtained by jogging the motor 32, continuous operation may be obtained by moving the pivotedmember 25 toward the guard ring 28 so as to release the jog button for movement to its normal position and by then depressing the start button 38. Although the energizing circuits for the winding 31 may be interrupted at any time by depressing the jog button I9 to its intermediate position, it may be desirable to provide for stopping the motor 32 at any time from some remote point. It will be apparent that this stopping of the motor may be accomplished by depressing the stop button 48 which may be located at any desired point.

While we have shown a particular embodiment of our invention, it will be understood, of course that we do not wish to be limited thereto since many modifications may be made and we, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

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

1. In combination, an electroresponsive motorstarting switch having an energizing circuit and a maintaining circuit, a push button operated switch having normally closed contacts common to both circuits and normally open contacts, said contacts being operable by a common push button, means automatically responsive to depression of said push button from said normal position for maintaining said normally closed contacts in open circuit position while providing for selective closure and opening of said normally open contacts by said push button, circuit connections for establishing an independent energizing circuit for said starting switch when said normally open contacts are closed, and manual means for releasing said automatic means to permit reclosure of said normally closed contacts.

2. In combination, an electroresponsive motorstarting switch having an energizing circuit and a maintaining circuit, a push button operated switch having a pair of spaced stationary contacts common to both circuits and a bridging member connected to said push button, means biasing said push button and said bridging memher to cause said bridging member to engage said contacts, a second pair of spaced stationary contacts, said bridging member being depressible by said push button to disengage said first pair of contacts and to engage said second pair of contacts, means automatically responsive to depression of said push button for restricting said bridging member to movement between said second pair of contacts and an intermediate position, circuit connections for establishing an independent energizing circuit for said starting switch when said bridging member engages said second pair of contacts, said independent circuit being interrupted by release of said bridging member to said intermediate position, and manual means for releasing said bridging member for movement to said normal biased position.

3. In combination, an electroresponsive motorstarting switch having an energizing circuit and a maintaining circuit, a push button operated switch having spaced apart stationary contacts and a movable contact member cooperating with said stationary contacts connected to said push button, means biasing said push button and said contact member to provide normally closed and normally open contacts, said normally closed contacts being common to both circuits and said movable contact being depressible by said push button to open said normally closed contacts and to close said normally open contacts, means automatically responsive to depression of said push button for restricting said movable contact to movement between its depressed position and an intermediate position selectively to close and open said normally open contacts, circuit con nections for establishing an independent energizing circuit for said starting switch when said normally open contacts are closed, and manual means for releasing said movable contact for movement to said normal biased position.

4. A control system for an electroresponsive motor-starting switch comprising a start button and a jog button, means operable by said jog button comprising spaced apart stationary contacts and a movable contact member connected to said jog button, means biasing said "jog button and said contact member outwardly to cause said contact member to provide normally closed and normally open contacts, said movable contact being depressible by said jog button to open said normally closed contacts and to close said normally open contacts, circuit connections including said normally closed-contacts for establishing an energizing circuit for said switch when said start button is depressed, circuit connections also including said normally closed contacts for establishing a holding circuit when said switch is energized, whereby said switch is maintained energized after said start buttonis released, circuit connections for establishing an independent energizing circuit for said switch when said movable contact is operated by said jog button to close said normally open cont-acts, means automatically responsive to depression of said jog button for restricting said movable contact to movement between said depressed. position and an intermediate position whereby said holding circuit is rendered ineffective, said movable contact being depressible from and releasable to said intermediate position selectively to establish and interrupt said independent energizing circuit, and manual means for releasing said movable contact for movement to said normal position.

5. A control system for an electroresponsive device comprising push button means for partially completing an energizing circuit for said device, means operable with said device for partially completing a holding circuit therefor, a second push button means, means normally biasing said second push button means outwardly to one position to complete said energizing and-said holding circuits when said first push button means is operated to energize said device and operate said holding circuit means, saidsecond push button being depressible to open both of said circuits, latching means automatically responsive to movement of said-second push button to depressed position for restricting said second button to movement between said depressed position and an intermediate position, whereby said second push button is prevented from completing said circuits, circuit connections for completing an independent energizing circuit for said device when said second push button is in said depressed position, said independent energizing circuit being interrupted by release of said second push button to said intermediate position, and means for releasing said latching means whereby said second push button returns to said biased position to prepare said first-mentioned circuits for closure upon operation of said first push button.

6. A push button switch comprising a pair of spaced apart stationary contacts, a movable contact, means biasing said movable contact to one position to engage one of said stationary contacts, a push button for operating said movable contact to another position to engage another of said stationary contacts, means automatically responsive to an operation of said push button to operate said movable contact from said one position for restricting said contact to movement between said other position and an intermediate position to prevent reengagement of said movable contact with said one stationary contact, and manual means independent of said push button for operating said restricting means to permit said movable contact to return to said one position.

7; A push button switch comprising a casing having an aperture, a push button movable through said aperture, a plurality of spaced apart stationary contacts, a movable contact within said casing, means biasing said movable contact to one position to engage one of said stationary contacts, a connection between said push button and said movable contact whereby said movable contact is operable by said push button to another position, means including a spring pressed latch within said casing responsive to an operation of said movable contact from said one position for limiting said movable contact to movement between said other position and an intermediate position to prevent reengagement of said movable contact with said one stationary contact, and means operable from outside of said casing for withdrawing said latch to permit said movable contact to return to said one position.

8. A push button switch comprising a casing having an aperture, a push button movable through said aperture and having a shoulder formed thereon within said casing, a contact within said casing, means biasing said contact to one position, means connecting said contact to said push button whereby said contact is operable by said push button to another position, a spring pressed latch normally engaging the circumference of said shoulder on the push button, said latch being automatically operable when said push button is depressed to a position to engage a side of said shoulder when said push button is released, whereby said contact is thereafter limited to movement between said other position and an intermediate position, and means movably extending through said casing adjacent said push button and operable from outside said casing for withdrawing said latch from engagement with said shoulder to permit said contact to return to said one position.

THOMAS I. MASLIN. ROY N. THOMAS.

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