US1339922A

US1339922A - Switch for electric circuits

Info

Publication number: US1339922A
Application number: US616474A
Authority: US
Inventors: Deutsch Isidor
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1911-03-23
Filing date: 1911-03-23
Publication date: 1920-05-11
Anticipated expiration: 1937-05-11

Description

I. DEUTSCH.

SWITCH FOR ELECTRIC CIRCUITS. APPLICATION HLED 111111.23, 191i. RENEWED NOV. 19, 1919.

1,339,922, Emma May11,1920.

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SWITCH FOR ELECTRIC C IRCUITS. APPLICATION FILED MAR. 23, 1911. RENEWED NOV. 19,1919.

1,339,922. Patented May 11, 1920.

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UNITED STATE PATENT ISIDOR DEUTSCH, 0F AVALON, PENNSYLVANIA, ESSIGNQR T0 'WESTINGI-IOUSE ELEC- TRIO AND MANUFACTURING COMPANY, A GOBPORATISN OF PENNSYLVANIA.

SWITCH FOR ELECTRIC CIRCUITS.

Specification of Letters Patent.

Application filed March 23, 1911, Serial No. 616,474. Renewed November 19, 1919. Serial No. 339,065.

To all whom it may concern:

Be it known that I, Ismon Dnu'rsor-r, a citizen of the United States, and a resident of Avalon, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Switches for Electric Circuits, of which the following a specification.

My invention relates to switches and sys tems for the control of electric circuits and motors, and it has for its object to provide a simple and particularly advantageous switching device for use in connection with motor control systems of the unit switch type.

Unit-switch control systems, which have been very largely used, comprise a plurality of independently operated switches designed and connected to act successively to govern the acceleration of electric motors. In these systems some independent means are ordinarily employed for delaying the action of the successive switches in order to avoid injuring the motor by excessive current.

According to my present invention, 1 provide an electric switch having the characteristic of occupying its open position, not only when its actuating magnet is de'e'nergized, but also when energized above a predetermined value. In other words, the switch is closed only when energized between predetermined limits. By utilizing a plurality of switches of this character in a simple, unit-switch control system, the acceleration of the motor may be advantageously accomplished and the a tion of each switch will be delayed until the current traversing the motor circuit has sufliciently decreased to fall within the limits which determine the action of the switches.

In addition to the above-named characteristic, the switch, when closed, will remain closed until its actuating magnet winding is denergized.

Figures 1 and 2 of the accompanying drawings are, respectively, a side and a front elevation of a switch constructed in accordance with my invention, the actuating coil being shown in section in Fig. 1. Fig. 3 is a diagrammatic view of a control system to which the switch of Figs. 1 and 2 is applicable, and Figs. 4 and 5 are views, corresponding to Figs. 1 and 2, of a slightly modified structure which is specially adapted for use with alternating current cirouits.

Referring to Figs. 1 and 2 of the drawings, the switch here shown comprises a stationary contact member 1, a movable contact member 2, a stationary core member 3 and a movable core member 4 to which the contact member 2 is pivotally secured. The stationary core member 3 is of substantially shape, having three

legs

5, 6 and 7, the leg 7 of which is adjustable. On the intermediate leg 6, a coil 8 is mounted, and the movable core member 4 is pivotally secured to its outer end. The core leg 5 and the movable core member 4 are, respectively, provided with

pole pieces

9 and 10 which are in engagement when the switch is closed. The end of the movable core member 4 that is adjacent to the leg 7 is provided with a set screw 11, or some other suitable means for fining the air gap between the two members when the switch is open, the member 4 being so formed that there is a material air gap either at one of its ends or at the other. A compression spring 12 is interposed between a projection 13 of the contact-bearing member 14 and a bracket 15 upon the outer surface of the member 4 in order to effect a rotative movement of the contact-bearing member upon its pivot 16 ano thus produce a wiping ation between the contact members when the switch is opened. The rotative movement of the contact-bearing member is limited by a projection 17 in order to hold the spring 12 in position and to permit the contact members to be properly separated when the switch is opened.

The adjustment of the leg plished by screw-threading its engage a tapped hole in the base of the member 3, as shown in Fig. 1, and its position may be fixed against accidental displacement by means of a clamping bolt 18 or otherwise. The lower end of the member 8 is provided with a slot 19 which extends into the tapped hole so that the clamping bolt, when tightened as shown in Fig. 2, locks the leg 7 in position.

The operation of the switch is as follows:

Assuming that the coil 8 is deenergized and that the switch is open, the lower end of the member 4 being separated from the 7 is accominner end to core leg 7 only by means of the set screw 11;

if, under these conditions, a large current is supplied to the coil 8, a large amount of flux will traverse the magnetic circuit constituted by the upper half of the core memher and including the

core legs

5 and 6. Another magnetic circuit will be established through the lower half of the core member including the core legs 6 and 7. The

pole pieces

9 and 10 and the air gaps are so proportioned that, under the conditions outlined above, the core leg 5 will be saturated so that a suflicient flux will traverse the leg 7 to hold the switch open regardless of the

pole pieces

9 and 10.

As soon as the current traversing the coil 8 falls below a predetermined value, the pull exerted between the core leg 7 and the movable core member 4 will decrease very rapidly so that the pull at the opposite end will predominate and the switch will be closed. If the current first applied to the coil is below a predetermined value, the switch will be closed on account of the size of the

pole pieces

9 and 10.

Referring to Fig. 3 of the drawings, the control system here shown comprises

line conductors

20 and 21, a line switch 23,

resistance sections

241, 25 and 26, accelerating

switches

27, 28 and 29 and a master switch 30. Assuming that each of the

switches

27, 28 and 29 has the same operating characteristics as the switch shown in Figs. 1 and 2, if the master switch 30 is closed, current will be supplied to magnet 31 of the line switch 23, causing this switch to close the circuit to connect the motor 22 in series with the resistance sections. The motor circuit is from conductor 21, through the motor, conductor 32, line switch 23, magnet winding of the switch 27,

resistance sections

24, 25 and 26 and conductor 34 to line conductor 20.

In accordance with well known principles, a rush of current will first traverse the motor circuit and the switch 27 is so designed as to remain in its open position until the motor has accelerated somewhat and the current has fallen below a predetermined value. It will then close and short circuit resistance section 24, thus completing the motor circuit from the line switch, through coil 33, the switch 27 and coil 35 of switch 28 to an intermediate point 36 in the resistance, from which circuit is completed as before. The action of the switch 28 is similar to that of the switch 27 and, when closed, short-circuits the resistance section 25 and supplies energy to the coil 37 of the switch 29.

The advantages of my electric switch will be immediately apparent to those skilled in the art and, consequently, they will only be briefly referred to as follows:

No series relay or other independent means for delaying the action of the switches is required: no auxiliary contacts are necessary for the purpose of interlocking the switches: each of the switches may be identical in construction and at the same time the limits within which the switch will be closed may be adjusted by varying the air gap between the members 7 and 4 when the switch is open. This is accomplished as shown in Fig. 1, by adjusting the setting of the screw 11.

Referring to Figs. 4 and 5 of the drawings, in which corresponding parts are designated by the same reference characters, the coil 8 of Fig. 1 is replaced by

coils

38 and 39, respectively located on the core legs 5 and 7, and the structure of the core member itself is laminated for the purpose of adapting it to alternating current circuits. The core leg 7 forms a butt joint with the body of the core and brackets 10 are attached to the body by means of bolts 41. The arrangement of parts is such that when the lower ends of the brackets 10 are bolted together the position of the core leg 7 is fixed.

Variations in the size and arrangement of parts of the switch may be effected within the spirit and scope of my invention and it is capable of very wide application, the sys tem of Fig. 3 being intended merely to illustrate its utility.

I claim as my invention:

1. An electro-magnet comprising a substantially E-shaped core member, a relatively movable core member pivotally secured to the intermediate core leg of the E-shaped member and an actuating coil, a relative movement of the core members being effected only when the current traversing the coil falls within predetermined limits, one of the legs of said E-shaped member and said relatively movable member having enlarged pole pieces.

2. An electro-magnet comprising a substantially E-shaped core member having one of its core legs adjustable, and a relatively movable core member pivotally secured to the intermediate core leg of the E-shaped member and an actuating coil, a relative movement of the core members being effected only when the current traversing the coil falls within predetermined limits.

3. An electro-magnet comprising a substantially E-shaped core member having one of its core legs adjustable, and a relatively movable core member pivotally secured to the intermediate core leg of the E-shaped member, a coil, and adjustable means for fixing the minimum air gap between the movable core member and the adjustable leg of the E-shaped member, a relative movement of the core members being effected only when the current traversing the coil falls within predetermined limits.

at. An electromagnet comprising a switchcarrying member pivoted intermedlate 1ts ends, two magnetizable members respectively adjacent to said ends, one of said magnetizable members being larger than the other, and means for creating two magnetic circuits to respectively include said magnetizable members.

5. A controlling device for electric circuits comprising an electromagnet having two core members, a pivoted switch member having an armature portion cooperating with each of said core members and normally .in open position, with one armature portion resting adjacent to the free end of one core member but separated therefrom by an air gap, one of said core members being of smaller cross-sectional area than the other, whereby it becomes saturated to cause the flux of the magnet to cross the gap through the larger core member and thereby hold the switch open when the current is high but so reduces the flux across said gap, when the current falls to a predetermined value, that the switch may be closed by the flux acting upon the other armature portion.

6. In a switch, a magnetic circuit including a stationary mechanism, a movable mechanism and a winding associated with said stationary mechanism for producing magnetic pulls on said movable mechanism at two places, said circuit including also a gap for causing the pulls to vary differently at said two places when the ampere turns in said winding are varied, and means for adj usting both o1 said mechanisms to vary said gap and thereby vary the relation between said pulls 7. An electromagnet comprising a base having a screw-threaded opening and a slot leading therefrom, a screw-threaded core member adjustably mounted in said opening and a bolt for restricting the area of said slot to clamp said core member in adjusted position.

8. An electromagnet comprising a base having an opening and a slot leading there from, a core member adjustably mounted in said opening and means for drawing the walls of said slot toward each other to clamp said core member in adjusted position.

9. An electromagnet comprising a movable switch member pivoted at a point intermediate .its ends, two magnetizable members respectively adacent to said ends, and means for energizing two magnetic circuits of difi'erent reluctances, said circuits respectively including said magnetizable members.-

10. An electromagnet comprising a movable switch member, two magnetizable members respectively adjacent to coacting portions of said movable member, and means for energizing two magnetic circuits, respectively including said magnetizable members, to such degrees that only one of said magnetizable members is saturated.

11. An electromagnet comprising a member having a pivotal support intermediate its ends, two magnetizable members respectively adjacent to said ends, one of said members being of greater magnetic reluctance than the other, and means for energizing two magnetic circuits respectively including said magnetizable members.

12. An electromagnet comprising a member having a pivotal support intermediate its ends. two magnetizable members respectively adjacent to said ends, one of said members being of greater cross-section than the other, and means for energizing two magnetic circuits respectively including said magnetizable members.

In testimony whereof, I have hereunto subscribed my name this 14th day of March, 1911.

ISIDOR DEUTSCH. Witnesses W. BARNES, (In, B. B. HINns.