US665903A - Rheostat. - Google Patents

Description

no. 665,903.. Batman Ian. l5, |9ol.

E. M. HEWLETT.

,i nHEos'rAT.

(Application Bled Nov. 13, 1900.)

(No lodgl.) 2 Sheets-Sheet l.

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Witnesses. I. j Jnv'entor b Edward M. Pievvletpip', y

YH: News Perma co, ro'rmwuo., msumurow. n. c.

Patented lan. I5, |90l.`

No, 665,903.Y

E. M.'HEWLETT.

' RHEosTAT.

(Applicatiqn led Nov. 13, 1900.)

A 2 Sheets-Sheet 2.

(N0 Model.)

lrwentl"l Edward MfHewlett,

Witnesses UNITED STATES l-ATEEVF OEEICE.

EDWARD M. HEWLETT, OF SCHENECTADY, NEIV YORK, ASSIGNOR T TI-IE GENERAL ELECTRIC COMPANY, OF NEV YORK.

RH EOSTAT..

SPECIFICATION forming part of Letters Patent No. 665,903, dated January 15, 1901.

Application led November 13, 1900. Serial No. 36,362. KNO model.)

To all whom it may concern: nitely indicated in the claims appended to Be it known that I, EDWARD M. HEWLETT, a this specification. citizen of the United States, residing` at Schen- In the accom panying drawings, which illusectady, county of Schenectady, State of New trate my invention, Figure l is a front eleva- 55 York, have invented certain new and useful tion ofa motor-driven rheostat employing my Improvements in Rheostats, (Case No. LMA) improvements. Fig. 2 is a sectional elevation of which the following is a specification. on a plane at right angles to that of Fig. l.

This invention relates to I )ower-controlled Fig. 3 is a diagram showing the plan of conrheostats, the object being to permit the in struction of the rheostat and its relation to 6o 1o troduction or withdrawal from the circuit to the governed and controller circuits, and Fig.

be governed of a desired variable amount of 4 is a detail View of the rheostat-brush.

resistance, the resistance-switch being gov- Referring `first to Figs. l and 2, the rheoerned by a source of power controlled by an stat is composed of a range of copper orphosoperator. phor-bronze contacts l l lb, dac., solidly 65 One particular use of the invention is the mounted on a slate base and separated by an regulation of resistance in the field-circuit of air-space or otherwise insulated one from ana dynamo-electric machine for varying the other. I preferably arrange thesein the form voltage of the machine, it being desirable to of a circle, mounting` within the circle an be able to manipulate a device of this charannulus of conductive metalZ, between which 7o zo acter by means of a control-switch at a disand the several contacts cross-connection tance from the rheostat. may be made by means of a laminated phos- In carrying out my invention I provide a phor-bronze brush 3, spanned by a yoke on range of contacts electrically connected with the end of a cast-metal arm 4, journaled in a different resistance sections or spools of the bushing mounted in the base. Bolted to this 75 rheostat, in coperative relation to which I brush-arm and insulated therefrom is a shaft provide a brush-contact operated by an elec- 5, carrying a worm-gear 6, inclosed within a tric motor connected with a speed-varying cast-metal casing 7, supported by and formand current-reversing controller. I provide ing a part of a spider 8, bolted to the base by also an automatic switch for opening the moarms 9 9a, dac. The worm-gear engages a 8o 3o tor-circuit independently of the controller as worm 10, mounted on a shaft jointed to the the limit of travel over the range of contacts shaft of an electric motor l1 by a iiexible is approached at either end, these limitjoint, as indicated at l2. Between the sevswitches being so arranged that the motoreral contacts la lb, thc., are interposed seccircuit will always be in proper condition to tions of a continuous resistance in the usual 85 start the rheostat into action. I provide also manner, the segment l being disconnected means for indicating to the operator whether so as to form a dead-point upon which the the rheostat is in working order, employing brush may rest when the circuit is open. Sefor this purposeatelltale device which gives cured to the brush 3 is a plate or bar 13,

a visual or other indication when the rheobridging the under side of the contacts and 9o 4o stat-contacts are in proper engagement fora the ring-contact 2 and holding the brush or stable condition of the circuit, thereby prebridging contact 3 down into iirm engageventing the rheostat being left in a position ment with the face of the rheostat. Thus the where these contacts d0 not have agood curbrush is independent of the arm 4, but may rent-carrying capacity, and thus avoiding be pushed by it in either direction, as is evi- 95 damage to the apparatus. dent from Fig. 1l. This construction permits My invention embodies also features of the the brush to make a good contact at all times motor-controller by which the movements of Whether the arm is in true parallelism to the the power-governed rheostat are quickly arcontact or not. An auxiliary insulated brush l rested when the circuit is opened. or bridging contact le is mounted on bar 13 roo 5o The novel features will be more particuand cross-connects a ring 15(1nore clearly larly hereinafter described and will be deiseen in Fig. 3) and any one of the range of contacts governing a telltale or indicator, as will be presently set forth. As thus organized, the rheostat and its operating-motor may be mounted near the machine to be governed or at any other suitable point, connec- -tions being led therefrom to the circuit to be governed-as, for example, thefield-magnet of a dynamo-electric machine-and to the controller by which the movements of the rheostat are governed, which latter may be mounted on a switchboard with suitable indicating instruments.

1n the diagram, 17 represents the armature, and 18 the held-magnet, of a generator the potential of which it may be desired to regulate, and A B represent the bus-bar or mains, with which the Generator may connect 19 represents the telltale, the type shown being a visual indicator-as, 'for example, an incandescent lamp-in a branch circuit from the bus-bar, the closure oi which is determined by the auxiliary brush 11, which spans the ringcontact 15 and the contacts 16 16, ttc. These telltale-contacts are arranged in an annular group and are the same angular distance apart as the main contacts 1 1, the., ot the rheostat. They subtend, however, a smaller angle, serving thus to indicate by means of the lamp 19 when the brush 3 is squarely upon one of the contacts of the rheostat. 1f the latter bears upon one edge only of one of the contacts, the telltale-contact Will not be bridged, and the lamp will therefore not be lighted. One termin al of the circuit to be governed-forexample, the held-magnet coil 1S-may be connected with the ring-contact 2 of the rheostat and one end of the resistance with the main A, the other end of the field-coil being` connected with the main B. At or near the limits of movement of the rheostat-brush l place limit-switches 2O 20, being pivoted switches provided with projections lying in the path of an insulated projection 21, mounted on the end of the brush-arm. These are set in a short distance from the end of travel of the brusharm, so that the momentum oi the motor after it is cut ont may be absorbed in carrying` the brush to the open-circuit position, and when one limit-switch is open the other is closed and adapted to reverse the direction of operation of the rheostat. Inl the return movement of the brush the projection 21 strikes the pivoted switch-lever 2O or 2O1 (according to the direction of movement) and recloses thelimit-switch. These limit-switches are interposed in the armature-circuit of the motor which drives the rheostat and in such relation, as indicated in Fig. 3, to two Wires 22 22, leading to the controller, as to give opposite directions of movement to the armature. The controller is provided with a fixed range of contacts and a movable drum adapted to reverse the motor-circuit or cut in or out resistance to vary its speed. The controller is so designed that after the armature is disconnected from the line it is shortcirc uited fora moment before the held-circuit is opened. ln starting 'the motor the lirst movement ofthe controller in either direction closes the field-magnet circuit, then opens the short circuit for the armature, and cuts thc armature into line with resistance. The second movement cuts out the resistance, thus permitting the motor to speed up. 'lhus in the position indicated in the diagram the field-magnet circuit ot' the drivingA motor is open and the armature-circuit is closed by way of conductor 23, contacts 20 20, wires 22 22, controller-contacts 24- 25, bridging-contact of the controller to contact 2G to the other brush olf the armature. By moving the controller in either direction this short circuit is openedA and the field-magnet circuit closed by way oi" contact-s 27 2h and 2.() SO, this circuit including a blow-out magnet 3l, as usual in the construction ot' controllers. The next position of the controllercloses the armature-circuit, asindicated in the position marked 1 in the diagram, in which case thc armature-circuit is closed through the resistance 32. The final position of the controller is indicated by the dotted lines 2 2 in the diagram, in which the resistance has been cut out and the motor is at maximum speed. The operator recognizes by the blinking of the lamp 1.() that the rheostat is in good working order and also knows when a suilicient amount of resistance is out in exactly at what point to leave the rheostat, since if the lamp 19 is not lighted the motor must be started ahead a triile until the lamp burns, when the best relation of contact engagement between the rheostat-brush and its contacts is maintained.

What 1 cia-im as new, and desire to secure by Letters Patent of the United States, is

1. A. power-driven rheostat comprising a motor, and a limit device i`or cutting out the motor, automatically operated when the rheostat-contact nears its limit of movement.

2. A motor-driven rheostat comprising an electric motor, a rhecstat contact driven thereby, a circuit-controller `for the motor, and limit-switches to automatically interrupt the motor-circuit near the limit-s of travel of the contact. 3. A power-driven rheostat comprising a motor, a movable rheostat-contact driven thereby to vary the resistance, and a limit device to cut in or out the motor as the contact passes or returns to a definite point of its travel.

It. A motor-driven rheostat comprising a range of resistence-varying contacts, a contact-brush sweeping the same, an electric motor in gear with the brush, a limit-switch in the motor-circuit, and a projection moving with the brush to engage said switch at a definite point of its travel.

5. A power-driven rheostat comprising a vrange of resistance-varying contacts, a motor-driven brush adapted to successively engage the same, and a telltale or indicator to show when the contacts are in good conductive relation.

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6. A power-driven rheostat comprising a range of resistance-varying contacts, a motor-driven brush adapted to progressively engage the same, and an indicator operated when the contacts are engaged.

7. A power-driven rheostat comprising a range of resistance-varying contacts, a motor-driven brush adapted to progressively engage the same, and an incandescent lamp cut into circuit when the brush bears squarely on a contact.

8. A rheostat comprising a circular range of resistancevarying contacts, a movable brush to progressively engage the contacts, an arm carrying the brush, and a guide at the outer end of the arm to hold the brush in rm engagement with the contacts.

9. In a rheostat, a base-plate, a range of resistance-varying contacts mounted thereon, a brush-arm, a spider mounted on the baseplate, a gear-wheel attached to the arm and mounted on the spider, and a motor in gear with the wheel.

10. A power-driven rheostat comprising a range of resistance-varying contacts, a movable brush to progressively engage the same, an electric motor to drive the brush, and a controllei` provided with contacts to put the motor-armature on short circuit when the motor is cut out.

l1. A power-driven rheostat comprising a range oi' resistance-varying contacts, a movable brush to progressively engage the same, an electric motor to drive the brush, a controller to close the armature on short circuit when the motor is cut out, and a limit-switch on the rheostat to cut out the motor at a deflnite point of movement of the brush.

l2. The combination with a plurality of contacts, a brush movable thereon and held in engagement therewith, and a lever or arm loosely engaging the brush but mechanically disconnected therefrom.

13. A power-driven rheostat comprising a range of resistance-varying contacts, a movable brush to progressively engage the same, a motor to drive the brush, a circuit-controller and limit-switch at different points of the brush travel to automatically open the motor-circuit when the brush reaches a determinate position, said switches being connected to effect opposite directions of movement of the armature. v

In Witness whereof I have hereunto set my hand this 12th day of November, 1900.

EDWARD M. HEWLETT.

Witnesses:

BENJAMIN B. HULL, MABEL I-I. EMERSON.

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