US804344A - Electrical switching apparatus. - Google Patents

Description

PATENTED NOV. 14

W. J. RICHARDS. ELECTRICAL SWITCHING APPARATUS.

APPLICATION FILED NOV. 4. 1904.

4 SHEETS-SHEET 1.

izmewim/ No. 804,844. PATENTED NOV; 14, 1905.

W. J. RICHARDS.

ELECTRICAL SWITCHING APPARATUS.

APPLICATION FILED NOV. 4, 1904.

4 SHEETS-SHBET 2.

Elf Wall E1? J. I: and; mow/5 29052224", 5 %m% p PHgpr g N0- 804,34A. PATENTED NOV. 14, 1905. W. J. RICHARDS.

ELECTRICAL SWITCHING APPARATUS.

APPLICATION FILED NOV. 4, 1904.

4 SHEETS-SHEET 3.

WLFPEEE E1 WJWM EH zz ga WALTER J. RICHARDS, OF MILVAUKEE, WVISOONSIN.

ELECTRICAL SWITCHING APPARATUS.

Specification of Letters Patent.

Patented Nov. 14, 1905 Application filed November 4, 1904. Serial No. 231,338.

To a. whom it may concern:

Be it known that I, WALTER J. RICHARDS, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of lVisconsin, have invented a certain new and useful Improvement in Electrical Switching Apparatus, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to electricalswitching apparatus, and more particularly to an automatic rheostat especially adapted for use in conjunction with alternating-current motors.

A well-known type of alternating-current motors comprises a primary winding traversed by multiphase alternating currents, whereby induced currents are set up in a secondary winding or circuit, the reactions between the two circuits serving to produce the torque or rotative'effect in the motor. It is desirable to'control the starting-current supplied by such motors by means of current-restricting means associated with the secondary winding.

A preferred embodiment of my invention consists of such a motor having resistances normally included in the secondary circuit,

the resistances being provided with short-circuiting switches controlled by a slow-acting electromagnetic device, through which the circuit is closed upon the closure of the primary circuit, whereby the resistance in the secondary circuit is gradually cut out as the motor comes up to its normal speed, when the resistances, being completely short-circuited, no longer entail a loss of energy which would otherwise ensue.

My invention will be better understood by reference to the accompanying drawings, in which- Figure 1 is a diagrammatic view showing the electrical connections employed. Fig. 2 is a front elevation of the electromagnetic switching device which forms the subject of the present invention. Fig. 3 is a side view of the same, parts being shown in cross-section for purposes of clearer illustration; and

connected by means of the main switch 15. The secondary circuit of the motor is illustrated in the form of the star-connected windings 16, 17, and 18, the free terminals of these windings being connected, respectively, with the free terminals of the resistances 19, 20, and 21, resistances and windings being connected at their neutral points, as shown. The electromagnetic switching device serves gradually after the closure of the motor-circuit to cut the resistances 19, 20, and 21 out of the secondary circuit of the motor.

I shall first explain the mechanical construction of the electromagnetic device by reference to Figs. 2, 3, and 4 and then explain its operation in connection with the motor by reference to Fig. 1, upon which the parts of the electromagnetic switching device are provided with the same reference characters as those upon the other figures.

At 22 I have shown the base-plate carrying the standards 23, in which the shaft 24 is mounted, the shaft being preferably insulated, as shown. Upon the shaft is pivoted a swinging frame 25. This frame when in its lower position extends into a suitable depression 26, formed in the base-plate. The frame carries a contact-plate 27 and at one end an auxiliary contact-plate 28, insulated from the main contact-plate 27. Above the contactplates carried upon the frame 25 there are a number of contact-fingers 31 to 38, inclusive. Each contact-finger is provided with an adjustable stop in the form of a screw 39 and a locknut 40, these screws resting upon an ordinary rubber strip 41, supported upon the baseplate. The screws are so adjusted that the three contact- fingers 31, 32, and 33 normally rest in a position somewhat lower than that of any of the other contact-fingers. The next three, 34, 35, and 36, are adjusted to an intermediate position, while the two contact- fingers 37 and 38 are so adjusted that they will be higher than any of the other contact-fingers. Each contact-finger is provided with a spring 42, each spring opposing the upward motion of the associated contact-finger. The contact-fingers are insulated from each other and from the shaft 24, about which they may rotate, and each contact-finger is provided with a suitable binding-post 43, to which the contact-finger is connected by means of the pigtail 44. In Fig. 4 certain of the springs 42 are broken away to illustrate the electrical connection with the contact fingers. The movement of the frame 25 and its contactplates 27 and 28 is caused by means of a solenoid 4 1, the solenoid being placed within the laminated iron field-magnet 15, the lamina of this magnet being held in position by means of the side plates 16 and 47, the rivets 18 serving to clamp the side plates together. These side plates at their lower ends are provided with suitable feet 19, by means of which they are secured to the base-plate by the cap-bolts 50. Alaminated plunger or core 51 is mounted within the field-magnet and solenoid, the lamina of the plunger being held together and in position by means of the side plates 52, the rivets 53 serving to hold the side plates together. The side plates extending downwardly form a forked end within which the tongue 54 of the frame 25 is pivoted by means of the pin 55, these two members being preferably insulated from each other, as shown. At the upper end the core 51 is pivoted upon a forked lever 56 by means of the pin 57, the lever being adapted for oscillation about the pin 58, which is carried in suitable projections of the side plates 16 and 17. At its free end the lever 56 is .pivoted, by means of the pin 59, to the end of a piston-rod 60, to which the piston 61 is attached, this piston, with the cylinder 62, constituting a dash-pot which retards the upward motion of the core 51 when attracted on account of the energization of the field-magnet, within which it is mounted. The piston has a valve-plate 60 loosely held thereon by headed pins 61. Upon downward stroke of the piston this plate covers the large opening 62 through the piston and restricts the flow of air to the fine opening 63 and the motion of the piston is retarded. Upon upward motion, however, the valveplate exposes the large opening and the retarding effect is removed. The retractingspring 63 is connected at its upper end to the lever 56 and at its lower end to an extension 6 1 of the side plate 17, this extension serving also as a point of attachment for the lower end of the cylinder 62, the connection being made by means of the pin 65, which permits the oscillation of the cylinder required on account of the movement of the lever 56 about its fulcrum at 58.

As will appear from reference to the diagrammatic drawing of Fig. 1, the closure of the main switch 15 causes the closure of a circuit through the solenoid 14, whereby the magnetization of the field-magnet causes an upward attraction of the core 51, bringing the contact-plate 27 first into engagement with the three contacts 31, 32, and 33, and as these contacts are connected with points intermediate to the terminals of the resistances 19, 20, and 21 the inner portions of the resistances are short-circuited or cut out of the secondary circuit of the motor. The dash-pot serves to retard the upward motion of the core; but within a short time the contact-plate 27 is brought into engagement with the contact- fingers 34, 35, and 36, wereby the re maining portions of the resistances are shortcircuited out, thereby leaving the secondary windings of the alternating-current motor alone in the secondary circuit, except for the extremely low resistance of the contact-lingers of the switching device and the conductors leading to them.

Connected with the motor M, I have shown an air-compressor U, which supplies compressed air to the pressure system,represented by the tank T and the pipe P, leading therefrom to suitable pneumatic appliances. (Not shown.) The suction-Valves of the pump, as in my copending application, Serial No. 202,567, are retained normally in an open or unseated condition, due to the weight of the cores and 70. Thus during the initial supply of current to the motor there is no load upon the compressor; but as the contact-plate 28 comes into engagement with the contact-fingers 37 and 38 a circuit is closed from the main 11, through contact-linger 38, contactplate 28, contact-finger 37 to solenoids 71 and 71, and thence to the main 12. The energization of the solenoids 71 and 71 causing the upward attraction of their cores 70 and 7 0, respectively, removes the pressure of the levers 72 and 72 from the stems of the suction-valves, thereby permitting the valves to seat themselves and upon the continued operation of the compressor will cause the delivery of air through the discharge-valves into the reservoir T. \Vhen the motor-circuit is opened by means of the main switch 15, the solenoids 71 and 71' are deenergized, whereupon the weight of their cores 70 and 70 causes the suction-valves to be lifted from their seats. The deenergization of the solenoid 14; permits the return of the core 51 to its normal position, the downward movement of the core being moderated by the tension of the spring 63. As the contact- plates 27 and 28 return to their lower or normal position the electrical connections with the contact fingers are broken, thereby establishing the effective connection of the resistances 19, 20, and 21 with the secondary windings of the motor. The motor of'course comes to rest when its circuit is broken, where it will remain until the main circuit is again closed and the above-described operationswill be repeated.

While I have shown and explained one means of employing my present invention, 1 do not wish to be limited to its use for this purpose only, nor do I wish to limit myself to the precise construction set forth.

The principle and scope of my invention are indicated in the following claims:

1. In a device of the class described, the combination with a plurality of pivoted contact-fingers, of an adjustable stop for each finger, an oscillating contact-plate, electromagnetic means for causing the movement of said contact-plate, and retarding mechanism serving to retard the movement of said contact-plate upon energization of said electromagnetic means.

2. In a device of the class described, the combination with a plurality of pivoted contact-fingers mounted for rotation upon a common axis, adjustable stop mechanism for adj usting the normal position of each finger independently of the others,a moving contact-plate adapted for engagement with said fingers, an electromagnet, a' core for said magnet connected with said contact-plate whereby the plate is moved upon energization of said magnet, and a dashpot serving to retard the movement of said contact-plate upon energi- Zation of said electromagnet.

3. In combination, a plurality of contactfingers independently mounted for rotation about a common axis, adjustable stop mechanism associated with each contact-finger, a spring serving to maintain each contact-finger in a normal position, an oscillating contact-plate mounted to rotate about the common axis of said contact-fingers, a tongue extending from said contact-plate, an electromagnet-core connected with said tongue, a C-shaped field-magnet of laminated iron surrounding said core, a solenoid for said magnet, a lever serving to guide said core in its movements, and a dash-pot associated with said lever serving to retard the motions of said core.

4:. In combination, a laminated field-magnet 45, side plates 46 and 47, a core 51, a lever 56, a swinging frame 25, pivoted fingers to be engaged by said frame and a dash-pot associated with said lever, all substantially as described.

5. In combination, a resistance, a plurality of pivoted contact-fingers electrically connected with different points in said resistance, stops for said contact-fingers, an oscillating contactplate normally electrically disconnected from said contact-fingers, and electromagnetic mechanism adapted upon energization by an alternating current to bring said contact-plate into connection with said fingers.

6. In combination, an alternating-current motor having a secondary circuit, a fluidpump driven by said motor, an electromagnet controlling a valve of said pump, a resistance in the secondary circuit of the motor, a plurality of pivoted contact-fingers mounted for rotation about a common axis, stops serving normally to maintain said fingers in different positions, electrical connections between difi'erent points in said resistance and certain of said contact-fingers, a contact-plate adapted to be moved into engagement with the contact-fingers associated with said resistance and other contact-fingers connected in a circuit including said electromagnet, a second contactplate mechanically associated with the first contact-plate and moving therewith but electrically disconnected therefrom, and laminated electromagnetic mechanism adapted upon energization to cause the movement of said contact-plates, whereby the first contactplate engages the contact-fingers associated with said resistance, and thereafter the second contact-plate engages the contact-fingers associated with said electromagnet and a retarding device for retarding the movements of said contact-plates.

7. In combination, a C-shaped field-magnet of laminated iron, side plates for said fieldmagnet, an extension formed integrally with one of the side plates, a core for said fieldmagnet, an electromagnet-coil for said fieldmagnet, a lever pivoted to said core and said side plates, serving to guide said core within the field of the magnet, a spring extending between said extension and said lever, a dashpot cylinder pivoted to said extension, and a piston for said dash-pot connected with said lever, substantially as described.

8. In combination, a C-shaped field-magnet of laminated iron, side plates for said fieldmagnet, an extension formed integrally with one of the side plates, a core for said fieldmagnet, an electromagnet-coil for said fieldmagnet, a lever pivoted to said core and said side plates serving to guide said core within the field of the magnet, a dash-pot cylinder pivoted to said extension, and a piston for said dash-pot connected with said lever, substantially as described.

9. In a device of the class described, the combination with a plurality of pivoted contact-fingers, an oscillating contact-plate, electromagnetic means for causing movement of said contact-plate into engagement with said contact-fingers, a retarding mechanism serving to retard the movement of said contactplate upon energization of said electromagnetic means.

10. In a device of the class described, the combination with a plurality of contact-fingers pivoted at one end, of a contact-plate pivoted concentric with said fingers, electromagnetic means for moving said plate, toward said fingers, and an adjustable stop for each finger for normally maintaining groups of said fingers at various angles from said plate, whereby the groups of fingers will be engaged at different times.

11. In a device of the class described, the combination with a plurality of contact-fingers pivoted at one end, of a contact-plate pivoted concentric with said fingers, electromagnetic means for moving said plate toward said fingers, an adjustable stop for each finger for normally maintaining groups of said fingers at various angles from said plate, Whereby the groups of fingers will be engaged at different times, and means for retarding the movement of said frame.

12. In a device of the class described, the combination with apivoted contact-frame, of a plurality of contact-fingers pivoted concentric IIO with said frame, adjustable means for causing said fingers to assume various relative angles When said contact-frame is disengaged therefrom, electromagnetic means for swinging said frame toward said contact-fingers, whereby said fingers are successively engaged thereby, stationary terminal posts for said contactfingers, and flexible conductors connecting said posts with said fingers.

13. In a device of the class described, the combination with a pivoted contact-frame, of a plurality of contact-fingers pivoted concentric with said frame, adjustable means for causing said fingers to assume various relative angles when said contact-frame is disengaged therefrom, electromagnetic means for swinging said frame toward said contact-fingers whereby said fingers are successively engaged thereby, stationary terminal posts for said contact-fingers, flexible conductors connecting said posts with said fingers, and springs secured to said posts and engaging said fingers for holding said fingers in firm engagement with said contact-frame.

14. In a device of the class described, the combination with a pivoted contact-frame, of a plurality of contact-fingers insulated from each other and pivoted concentric with said frame, an adjusting-screw for each contactfinger, an abutment for each contact-screw, said fingers by means of said screws and abutments being adapted to be normally disposed at different angles to each other, electromagnetic means for swinging said frame about its pivot into engagement successively with the contact-fingers, and spring means for normally maintaining said contact-fingers against the abutments and for assuring firm electrical contact thereof with the contact-frame when actuated by said electromagnetic mechanism.

15. In a device of the class described, the combination with a contact-frame pivoted at one end to a stationary support, a core of electromagnetic mechanism connected with the other end of said frame, contact-fingers insulated from each other and pivoted concentric with said frame and adapted to he engaged thereby upon energization of the electromagnetic mechanism, a field-frame for said electromagnetic mechanism, a rigid arm extending from said field-frame, a lever pivoted at an intermediate point to said field-frame, one end of said lever engaging the other end of said core, and dash-pot mechanism connected with the other end of said lever and with said rigid arm adapted to retard the motion of said core to bring the contact-frame into engagement with said fingers. v

16. In a device of the class described, the combination with a contact-frame pivoted at one end to a stationary support, a core of electromagnetic mechanism connected with the other end of said frame, contact-fingers insulated from each other and pivoted concentric with said frame and adapted to be engaged thereby upon energization of the electromag netic mechanism, a field-frame for said electromagnetic mechanism, a rigid arm extending from said field-frame, a lever pivoted at an intermediate point to said field-frame, one end of said lever engaging the other end of said core, dash-pot mechanism connected with the other end of said lever and with said rigid arm adapted to retard the motion of said core to bring the contact-frame into engagement with said fingers, and adjusting means for causing groups of said lingers to be successively engaged by said contact-frame.

In witness whereof I hereunto subscribe my name this 28th day of October, A. D. 190 1.

WALTER J. RICHARDS. l/Vitnesses:

S. H. I-IooLEY, M. O. BLUMENFELD.

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