US1235684A - Electric switch. - Google Patents

Description

J. H. HALL,

ELECTRiC SWlTCH.

APPLICATION FILED MAR-18.

Patented Aug. 7, 1917..

UNITED s'ra'rns PATENT ornron.

JAY E. HALL, OF CLEVELAND, OHIO, ASSIGNOB, BY MESNE ASSIGNMENTS, TO THE ELECTRIC CONTROLLER & MANUFACTURING CGMPANY, A CORPORATION OF OHIO.

ELECTRIC swrrcn.

Application filed March 18, 1913.

To all whom it may concern:

Be it known that I, JAY H. HALL, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements in Electric Switches, of which the following is a specification.

My invention relates to magnetically-operated devices, and particularly to magnetically-operated switches.

One of the objects of my invention is to provide a switch having a single magnet or winding which has the characteristic of maintaining its contacts open not only when the winding is not energized, but also when it is energized above a certain value. The con tacts are closed when the current in the winding is at or below this value. Another object is to cause the contacts to remain closed as long as the winding is energized.

Referring to the accompanying drawing, Figure 1 shows in side elevation one of the many forms of switches embodying my invention. Fig. 2 is a wiring diagram showing the connections by which'a series of these switches may be used to control an electric motor;

On the drawing, the rectangular frame composed of magnetic material is provided with the magnetizing winding 2' which controls the core or plunger 3. The upper end of the core carries the movable switch contact 4: supported on a preferably non-magnetic stem. The contact 4.- when lifted bridges the fixed contacts 5. The upper member of the frame 1 contains an adjustable screw plug 6 composed of magnetic material and arranged in line with the core 3 to vary the length of the air-gap 12.

The lower member 9 of the frame 1 contains the screw 7 which is adjustable in line with the core and which forms a rest for the lower end of the core when the winding 2 is not energized or is energized above a predetermined value as hereinafter described: By

adjusting the screw 7 the length of the airgap between the core 3 and the frame-member 9 may be adjusted.

8 is a bar of ma etic material connected to the opposite si es of the frame between the top and bottom members thereof. I have shown the bar 8 integral with the sides of the frame. The winding 2 may rest on this bar, the core 3 extending through the same.

Specification of Letters Patent.

Serial No. 755,141.

The cross-section of the bar 8 is preferably smaller than that of the remainder of the bar 8, which furnishes the shortest return path for flux produced by the wlnding, can

not owing to its restricted cross-area, carry all the flux. Consequently, a portion of the flux is forced to flow through the lower end Patented Aug. 7,1917.

of the core and the lower member 9 of the frame by way of the air-gap 13. The magnetic pull across this air-gap assists gravity to hold the core in the same position that it occupies when the winding is not energized, that is, the magnetic pull across the gap 13 prevents the core 3 from rising.

When the current in the winding is reduced to the said value, the magnetic pull in the gap 13 becomes so diminished that the core will then be operated by the flux which traverses the ortion 8 of the frame and the air gap 12. hen the winding 2 is'energized with a current that exceeds a prede termined value, the switch remains open, and when thecurrent in the winding is reduced to that value, the switch operates to close its contacts.

I have shown at 10 a closed conductor on the portion 8 of the frame, which may be used to cause the flux initially produced by the winding to be dampened out of the portion 8 of the frame, and thereby to be made to enter the core through the frame member 9 and the air gap 13. Although the closed conductors 10 may be found to improve the operation of the switch, they are not essential for the successful operation thereof.

I have indicated at 11 a holding winding for the switch, which may be used to hold the switch closed after it has been closed by the winding 2. The circuit of the holding winding 11 may be independent of the circuit of the winding 2. If the winding 11 is connected in a shunt circuit across a source of supply when the main switch is closed, it should not be strong enough to close the switch, but strong enough to hold the switch closed after it has once been closed by the operating winding 2.

Referring to the wiring diagram in Fig.- 2, the motor to be controlled is shown at M; a main switch S is used to connect the motor system to a suitable source of supply; and the resistances R, R arearranged to regulate the current in the motor circuit during the acceleration of the motor. represent two of the switches shown in Fig. 1, the switch S having an operating winding only, whereasvthe switch S has an operating winding and a shunt holding windlng.

The operation of the system is as follows: Vhen the main switch S is closed, the holding winding 11 of the switch S is energized, but as before explained, cannot cause the operation of the switch. The motor circuit is from the positive through the motor M, the resistances R and R, and the operating winding of the switch S to the negative. The value of the current at this time will be limited only by the resistances R and R If it exceeds the value of current at which the switch S is adjusted to operate, the switch S will be locked open until the motor has increased its speed and thereby dimin-- ished the current in the motor circuit. WVhen it will close its contacts, short-circuit the re sistance R, and connect into the motor circuit the operating winding of the switch S The cutting out of the resistance R causes an increase'of current in the motor circuit which may be sufficient to lock the switch S open; but when the motor has further increased its speed, and thereby caused a reduction of current in themotor circuit, the switch S will operate and short circuit the resistance R as well as the operating windingsof the switches S and S The switch S drops open, but the switch S remains closed, this being due to. the holding winding- 11. The motor now operates at normal full speed. p I

To stop the motor, the switch S is opened, whereupon the motor is disconnected from the source of supply, the windingll becomes deenergized, and the apparatus re- S and S llIaroh, A. D. 1913. I

winding is above a predetermined value, and

close its contacts when the current is reduced. a

I claim- 1. In an electromagnetic device, a'mag' netic circuit having opposed poles, a magnetic shunt between the poles, and a reciprocablecore, separated from one pole by an operating gap and from the otherpole by a lock;out gap, and a single winding surrounding "the core and lying onthe opp'ositeside ofthe shunt from the look-out gap, the said shunt being of such restricted magnetic capacity as to force sufiicient flux across the lock-out gap when the winding is energized above a predetermined value to overcome the magnetic pull on the core across'tthe operat ing gap. v 2. In an electromagnet c switch, sw ich contacts, a magnetic circuit having. opposed poles, a magnetic shunt between the poles,-

and a reciprocable core,'separated= from one pole by an operating gap and from the other pole by a lock-out gap, and a single wlndlng surrounding the core and ly ng onthe opposite side of the shunt'i'rom the" look-out gap, the said shunt being of such restricted magnetic capacity as to force sufli-- I cient flux across the look-out gap when the winding is energized. above a predetermined value to overcome the magnet-icpull on the core across the operating gap andto allow the flux across the operating gap to move the core sovas to close said contacts when the energization of thewindin'g is reducedto the said value.

Signed at Cleveland, this' 15th day of JAYH. HALL.

Witnesses: V 1

RUTH H. BENNETT, H. M. DIEMER.

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