US1709725A - Motor-starting switch - Google Patents

Description

April 1929. H. D. JAMES ET AL 1,709,725

MOTOR STARTING SWITCH Filed 001;. 16, 1922 Fig.1. 29 as 6 I I? l I I I6 56 2.2, 24 I9 W as a5 a1 3'? l8 Fi .& 8

WITNESSES: INVENTORS fl% 1 Henry D. James E;

Charles H. Hodghms.

ATTORNEY Patented Apr. 16, 1929.

-UNITED STATES 1,709,725 PATENT OFFICE.

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MOTOR-STARTING SWITCH.

Application filed October 16, 1922. Serial No. 594,739.

! dition of the motor, or other device, controlled thereby.

The object of our invention is to provide a unitary starting switch for use with'small I motors or household appliances.

A further object of our invention is to provide a unitary starting switch in whlch a starting circuit and a running circult to a motor, or other device, are closed by a single operation of the switch handle.

It is also an object of our invention to provide a unitary starting switch in which a starting circuit and a running c1rcu1t to a motor, or other device, are closed by a smgle operation of the switch handle, and in whlch means are employed for automatlcally opening the starting circuit after a given interval of time, and means for opening the running circuit upon voltage drop.

Another object of our invention is .to provide a unitary starting-switch structure which shall be of few parts, simple of manufacture, compact in size and rugged in construction.

In the copending application of C. H. Hodgkins and Charles McL. Moss, Serial No. 546,108, filed March 23, 1922, and assigned to the Westinghouse Electric & Manufacturing Company, is shown and described an electric switch responsive to conditions of current overload or current failure. In this invention, we employ such a switch in combination with means for controlling the opening and closing of a starting circuit.

Figure 1 is a sectional view of a switch illustrating the preferred embodiment of our invention.

Figs. 2, 3, 4 and are diagrammatic views of the arrangement of several circuits controlled by the switch structure illustrated in Figure 1.

In the several views, similar reference numerals refer to like parts.

We provide a frame 1, having a cover 2, the latter being provided with openings 3 and 4 for the reception.v of push buttons or handles 5 and 6, respectively.

To the frame 1 are secured brackets 7 and 6 for the support of a thermal relay 9. A

brace or web 11 extends across the frame 1 mldway of its length and carries a bracket 12 supporting a dash pot 13, together with a pair of similar brackets 14, 15.

At the base of the frame 1, is a plurality of electrical terminals 16, 17 and 18 disposed 1n spaced relation to bosses 19 and 21, the latter being surrounded by coiled springs 22 and 23, respectively. Bosses 19 and 21 constitute uides for plungers 24 and 25, respective y. The boss 19 and the opening 4 1n cover 2 are in vertical alinement, and, with push button 6, constitute the supporting means for movable plunger 24. Plunger 24 is of a non-magnetizable metal and freely moves in the core member of an electro magnet 26 that is fixedly secured to the frame 1. Plunger is supportedsolely by the boss 21 and the spring 23.

Member 24 carries a plurality of pins 27, 28 and 29 that engage armature members .31and 32 which are pivoted to brackets 14 and 15, respectively. The opposite end of armature member 31 is connected to the piston 33 of dash pot 13. The second end of agmature member 32 carries push button Dash pot 13 comprises a piston 33 having a cross head 34 and a compression spring 35, although any preferred type of retarding element having a definite time action may be employed in lieu thereof. It is desirable that this member be designed to complete the final stages of its travel very quickly for reasons which will be hereinafter set forth.

Plungers 24 and 25 carry contact members 36 and 37, respectively, for making contact between terminals 16, 17 and 18 in any desired arrangement of circuits, as, for example, those shown in Figs. 2 to 5, inclusive.

As shown in Fig. 1, the contact member 36 is normally in the circuit-opening position, while contact member 37 is normally in the circuit-closing position. For these reasons, contact member 36 is so connected in the electrical circuits as to control the running circuit to the motor, or other device, while contact member 37 is connected to the starting circuit. By this arrangement, the closing of contact member 36 causes current to traverse all the electrical circuits including those controlled by contact member 37, as illustrated in Figs. 2 to 5, inclusive.

The operation of the switch mechanism commences upon the closing of contact member 36 by pressure upon the push button 6. Electromagnet 26 then becomes energized and attracts armature 32. The latter bears upon pin 29, causing the contact member 36 to be held in a closed position against the compression of spring 22. At the same time, the armature 32, turning about bracket 15, causes the push button 5 to be further projected above the cover 2. Push button 6 is for starting service while push button 5 is for stopping service.

In order to stop the motor, a pressure on button 5 is transmitted to the plunger 24 through the pin 28, when, with the assistance of the compression spring 22, the attraction of electromagnet 26 for the armature member 32 is overcome, causing the contact member 36 to interrupt the electrical circuits controlled thereby.

The continued energization of the electromagnet 26 attracts armature member 31 against the retarding influence of the member 13. After a predetermined time interval has elapsed, armature member 31 quickly turns about the bracket 14, striking the adjaeent end of plunger 25 a sharp blow, causing the contact member 37 to open and thereby disconnecting the starting circuit. Contact member 37 is held in the open position by the attraction of the electromagnet 26 for the armature member 31, as the latter continues to depress the plunger 25 against spring 23.

In case electromagnet 26 be de-energized, spring 23 closes the contact member 37, while spring 35 draws the armature member 31 into the position shown in Fig. 1, where the switch is in position for again starting the motor.

Upon increased energization, the armature member 31 is further attracted by electromagnet 26 in opposition to the springs 35 and 23 until armature member 31 strikes the pin 27. The combined forces of the electromagnet 26 and spring 22 are suflicient to overcome the holding action of armature member 32 on the plunger 24. The contact member 36 is then opened.

The electrical current may also be interrupted by a thermal relay 9, which may be employed separately, or in conjunction with pin 27, as desired.

So soon as the retarding member 13 has returned to its closed position under the illfluence of compression spring 35, the switch is again ready for starting the motor.

In the arrangement of apparatus and electrical circuits shown in Fig. 2, the holding coil for electromagnet 26 is connected in parallel connection with the motor running circuit 41, the total current from these circuits traversing the thermal relay 9. In parallel connection to these circuits is the starting circuit 42, which is opened by the contact member 37 as previously described. The manner in which contact member 36 controls the entire system is well shown by this figure.

Fig. 3 illustrates a different arrangement of the contact member 36 and thermal relay member 9, from that shown by Fig. 2, whereby the starting current is caused to traverse the thermal relay. In each of the Figures 2 and 3 the coil 26 is in shunt circuit with the running winding 41 and should the voltage of the system be disturbed, the coil 26 will not be affected within predetermined limits. If, however, the voltage should increase or decrease beyond the predetermined limits, the coil will function to cut the motor out of circuit.

Fig. 4 illustrates an electrical circuit having the electromagnet 26 in series with the motor, and the starting and running circuits, the latter two circuits being in parallel connection. The operation of the starting switch 37 causes the starting circuit 42 to be opened.

In the modification shown in Fig. 5, the opening of the contact member 37 serves to shunt an increased resistance 44 of a comparatively high value into the starting circuit 42, rather than opening this circuit as in the other modifications.

We have invented a starting switch in which a single electromagnet serves to protect the device in use from overload and voltage drop, and at the same time providing automatic means for opening the starting circuit at the roper time.

While we have shown the preferred form of our invention, and several of the ways in which it may be connected in various circuits, it is to be understood that such changes may be made in the structure and in the connections to electrical circuits as fall within the spirit and scope of the accompanying claims.

We claim as our invention:

1. In combination with a motor having a starting circuit and a running circuit, a unitary control switch having a switch member controlling both circuits and a second switch member for controlling the starting circuit, electroresponsive means for retaining the first said switch member in closed posltion and a timing device associated with the said electroresponsive means to enable it to operate the second switch member only after a predetermined time interval.

2. In combination with a motor having a starting winding and a running winding, a starting switch therefor comprising an electromagnet, a movable member mounted in said electromagnet, a contact member mounted on said movable member for controlling both windings, manual means for closing the said contact member, means associated with the electromagnet for retaining the contact member in closed position and a second means associated with the said electromagnet for rendering the starting winding ineffective after a predetermined time interval.

3. In combination with a motor having a starting circuit and a running circuit, a unitary control switch having a switch member controlling both circuits and a second switch member for controlling the starting circuit, electroresponsive means for controlling both of the said switch members, said clectroresponsive means being responsive to both the over-voltage and under-voltage conditions in the circuit for actuating one of the said switch members to open circuit position.

4. In combination with a motor having a starting winding and a running winding, a supply circuit therefor, a starting switch having a pair of switch members connected 'to the windings, a single electromagnet energized by the supply circuit for retaining the switch member in motor operating position, the said electromagnet being responsive to under-voltage and over-voltage conditions of the supply circuit to operate the switch members to open circuit position.

5. A motor control system including a motor havinga starting and running winding, a supply circuit therefor, a unitary starting switch having a single electroresponsive means in series with the circuit and responsive to over-voltage and undervoltage conditions thereof to control the said windings, means for producing a time delay between the operation of the windings and additional means within the switch responsive to thermal conditions for controlling one of the windings.

6. A motor control system comprising a motor having a starting and running circuit, a unitary starting switch therefor having a single electroresponsive means that is responsive to over-voltage and under-voltage conditions to control the said circuits, and additional means within the switch responsive to thermal conditions for controlling both of the circuits.

7. In combination with a motor having a starting circuit and a running circuit, a unitary control switch having a switch member controlling both circuits and a second switch member for controlling the starting circuit, manual means for actuating the firstsaid switch member, eleetroresponsive means for retaining it in actuated position and means responsive to the said electroresponsive means to operate the second switch member to render the starting winding ineffective after a predetermined time interval.

In testimony whereof, we have hereunto subscribed our names this 11th day of October, 1922.

HENRY D. JAMES. CHARLES H. HODGKIN S.

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