US445448A - holmes - Google Patents

Description

(No Model.) 5 Sheets-Sheet 1.

J. H. HOLMES. REGULATOR FOR DYNAMO ELECTRIC MACHINES.

N0. 445,448. Patented Jan. 2'7, 1891.

5 Sheets-Sheet 2.

R m d 0 M 0 W No. 445,448. Patented Jan. 27, 1891.

(No Model.)

' 5 Sheets-Sheet 3. J. H. HOLMES. REGULATOR FOR DYNAMO ELECTRIC MACHINES.

No. 445,448. Patented Jan. 2'7, 1891.

ill I g H m nu: mums pznzns cm, PHOTO-L c,

m Model.) 5 Sheets-Sheet 4.

J. H. HOLMES. REGULATOR FOR DYNAMQBLEGTRIG MACHINES. No. 445,448. Patented Jan. 27, 1891.

(No Model.) 5'Sheets-,Sheet 5. J. H. HOLMES.

REGULATOR FOR DYNAMO ELECTRIC MACHINES. No. 445,448. Patented Jan. 27, 1891.

UNITED STATES PATENT OFFICE;

JOHN ll. HOLMES, OF NElVCASTLE-ON-TYXE, ENGLAND.

REGULATOR FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 445,448, dated January 27', 1891.

Application filed May 14, 1890, Serial No. 851,771. (No model.) Patented in England December 17, 1889, No, 20,244, and in France March 31, 1890, No. 204,702.

T0 (1, whom it 'II'I/CLZ/ concern.

Be it known that 1, JOHN HENRY HOLMES, electrical engineer, a citizen of England, residing at Portlaml Road,Newcastle-0n lvne, in the county of Northumberland, England, have invented certain new and useful Improvements in Elect ric Generati n g Machinery for Use in Connection with the Electric Lighting of Railway-Trains, (for which I have received Letters Patent in England dated December 17,1881 No. 202%, and in France dated lvltllCll 31, 1890, No. 201L702) of which the following is a specification.

This invention relates to improvements in electric gei'ieraiing machinery for use in connection with the electric lighting of railwaytrains, and has for its object to construct an apparatus which will maintain a constantdif- 't'erenec of potential at the terminals of the dynamo-electric generator under a considerable variation in speed and when driven in either direction. Practically speaking, the electro-moti ve force of an ordinary separatelyexcited dynamo varies directly as the speed at which the armature revolves. So therefore, if the speed be increased, say, from live hundred revolutions per minute to one thousand revolutions per minute, the eleetro-motive force will be doubled. 'lhe clcctro-motive t'orce, however, varies also directly as the strength ot' the magnetic field, so that it the strength of field of the separately-excited dynamo be reduced in the same proportion as the speed at which its armature revolves be increased, then the electro-motive torceot' the armature will remain 'iractically constant.

To this end, according to my invention, I construct a dynamo-elect ric machine with two armatures arranged to revolve together, but in separate magnetic liel'ls. The one is the main generating-armature, the other being for regulating the strength of the magnetic field of the geuerating-armature.

I separately excite the magnets ot' the ma chine from some external source, such as a set of accumulators, and provide the magnets of the generatiug-armature with two dis tinct eXcitii'ig-circuits. One circuit isahighresistance shunt-circuit and the other is of less resistance and is coupled up to the source of current, so as to have the small regulatingarmature in series with it. The regulatingarmature is so coupled up that its own electro-motive force opposes the electro-motive force of the source of supply. sistance shunt-circuitis preferably so proportioned that at the highest speed at which the gencrating-armature is intended to be run it (without the aid of the second exciting-circuit) will give a magnetic field of an intensity proper for the required electro-motive force in the generating armature. \Vhen thus arranged, the second exciting-circuit ought to have no currentpassingthroughita result which is brought about by the electro-motive force of the regulating-armature being at the highest speed equal and opposite to the external source of electro-motive force by means of which the exciting of the magnets is accomplished. it, however, the speed falls, the electro-motive force of the regulating-armatu re is lessened in the same proportion, and, being no longer equal to the external electro-motive force, a current will be permitted to flow through the second exciting-circuit of the magnets of the generating-armatu re, thus increasing the intensity of the magnetic field to make up for reduction of speed, with the result of maintaining a practically uniform electro-motive force in the generating-a1mature.

\Vhen the speed falls to the lowest limit, which I will assume to be half the highest rate of speed, then the electro-motive force of the regulating-armature in the case I am considering will be half the electro-motive force of the external source of supply, so that it will be seen thatit is necessary to calculate the proportions of the second exciting-circuit of the generating-armature magnets upon the basis of only half the electric pressure of the external source of electro-motive force being available, and the resistance of the regulating-armature fOllllll'lg part of the circuit-1e sistance. At thelowest speed, therefore, half the exciting-power upon the generating-armature magnets will be produced by one coil having the full difference of potential of the external source of eleetro-motive force at its terminals and by a second coil having half the ditt'erence of potential of the external source of elcctro-motive force at its terminals,

The high-re less of course by the drop of potential due to the resistance of the regulating-armature, which forms a portion of this circuit.

In speaking of the proportioning of the parts I assume that the magnets of the generating-armature are used witha low magnetic density well below the saturation-point for the iron of which they are composed. I prefer to use them thus; but by careful allowances a sufficiently near result might be obtained with the iron in a condition more nearly saturated when the full exciting-power is on. I

lVhen I use an electric machine of the nature described for generating electric currents for the lighting of railway-trains in conjunction with the storage-batteries, I use the latter for the externalsource of electro-motive force, by which I excite the magnets, and drive the armature by means of gearing, which transmits the power from the axle of the van or vehicle in which the machinery is placed. I also arrange a centrifugal governor driven from the same source, which is made to switch on the circuitfrom the storage-batteries to the magnet-coils as soon as the speed rises to about the minimum speed at which the electric generating apparatus is intended to come into action, and which also switches off the current when the speed falls below the minimum speed.

As it is desirable that when the railwaytrain runs backward the dynamo would still be able to do its work properly, I prefer to make the brushes which collect current from the two armatures of copper-wire gauze and placed in positionsradial to the comm utators, being held in brush-holders attached to flat springs lying parallel to a tangent drawn to the surface of the commutator at the points at which the brushes bear. I also reverse the lead of the brushes of the generatingarmature when the direction of rotation changes by means of mechanism of the following description: The brush-holders are carried by arms which, in the usual manner, can be rotated together around the axis of the armature, the motion in either direction being limited by stops. The motion is transmitted from the axle of the machinethrough gearing coupled to'the axle and by means of a friction-clutch which slips round as soon as the brush-carrying arms are hard up against their stops.

To prevent any wearot the friction-clutch faces occurring excepting when the speed of the axle is very low, I arrange on the axle a centrifugal governor, the balls of which at a slow rate of revolution fly out and separate the faces of the friction-clutch, 'so'that they do not touch excepting at speeds below this low rate of revolution. When the direction of rotation of the armatures is changed the polarity of the brushes is alsochanged. I therefore utilize the motion which reverses the lead to Work reversing switches of a kind. well understood, so as to alter the con nections and keep the polarity at the terminals of the machine the same.

I do not find it necessary to make provision for reversing the lead of the brushes of the regulating-armatu re, because the current ru nning through this armature is usually small, and at maximum speed is, in fact, m'l. I therefore place these brushes i n fixed positions at the neutral points.

In order that my invention may be thoroughly understood, I will now proceed to describe an apparatus constructed in accordance therewith, for which purpose I will refer to theaccompanying drawings, in which- Figure 1 shows a side elevation of the combined generating and regulatingdynamo-machines; Fig. 2, a cross-sect ion on line T P; Fig. 3, a plan; Fig. Al, a view of the brushreversing gear on an enlarged scale; Fig. 5, a diagram plan of the circuitand connections. Figs. 6 and 7 are enlarged detail views of the switch for coupling the exciting-circuits of both dynamos with the accumulators. Figs. 8 and 9 are respectively a plan and an elevation of the automatic switch hereinafter referred to.

The generating-dynamo Q has its fieldmagnets L excited first by an ordinary highresistance shunt-circuit 0t, and secondly by a circuit 1), of less resistance, coupled upto the accumulator C, which is charged by the dynamo, and having the armature 0f the regulating-dynamo R in series with it, the regulatingdynamo being so coupled up that its own electro-motive force opposes the electro-motive force of the accumulator. The armature of the geueratirig-dynamo and thatof the regulating-dynamo are both fixed on the same shaft 0, driven by pulleys d from an axle of the vehicle. This shaft carries the commutator A of the geueratirig-dynamo, and the commutator I) of the regulating-dynamo. The brushes D of the commutator A are mounted in spring-holders D, carried by bars F, projecting from shiftable arms F F, mounted loose on the armature-shaft 0, so that, ac cording as these arms are brought from one inclined positionsuch as that shown at Fi 4to an opposite one, the brushes which are held in a radial position on the commutator have the requisite lead imparted to them on the one or the other side of the vertical center line, according as the armature-shaft is rotating in the one direction or the other.

The arms F F are connected together by pins F andv these pins are made to enter between the one or other pair of contact-jaws S S or S S, connected, respectively, to the screw-terminals T T for the circuit-wires, so

that as the polarities of the brushes are reversed, on the reversal of the motion of the armature-shaft their connection with the circuit is at the same time reversed by the movement of the arms F. The jaws S S on the right-hand side are coupled; respectively,with the jaws S S on the left-hand side by means of copper bars S S The reversal of the position of the arms:

and brushes on the reversal of the motion of the shaft effected as follows: Loose upon the shaft is a friction-disk N, to which vis fixed a pinion X, gearing with a toothed sector I fixed on a spindle passing through the standardcarrying the rocking arms F, which spindle has fixed on its other end a pinion F", gearing with a toothed sector F on the boss of the arms F.

A second frictiondisk N is carried round by the shaft, but can slide longitudinally upon it. lhis disk has a neck, into which take the ends of the arms of the governor M, fixed on the shaft, the weights of which are drawn together by springs 0, so as, when at rest or moving very slowly, to cause the arms to press the disk N against the disk N with a certain amount. of frictional contact. From this arrangement it will be seen that if, after having revolved in one direction, the armatureshaft is made to revolve in the contrary direction by the reversal of the motion of the carriage the disk will carry round with it the disk N, and in thus turning the pinion N, the sector F and pinion I will cause the arms F to be brought into the opposite inclined position, thereby reversing the position of the brushes and. contacts, as above described. As soon as the arms I have passed as far as they can into the jaws S or S, so as to be arrested in that position, the disk N will slip upon the disk I\' until the speed of the shaft 1,: has increased sufficiently to cause the governor .d to draw the disk N backward out of contact with the disk N, in which position it-will continue as long as the machine is running.

The disk N has a groove which is embraced by the fork of an arm Nflwhiclnwhcn the disk is slid backward to a certain extent by the QO\'Glll0l,\\lll act upon the switch ll, Figs. 0 and 7, that couples up the exciting-circuits of both dynamos with the accumulators, the resistance of the governor-springs 0 being so arranged that these contacts are not made until the armature-shaft has attained a cer tain speed slightly under the minimum speed at which the dynamo is intended to generate current. The switch ll may be a doublebreak ln'idgt-i-over switch, made of two bars n n, rigidly connected by a cross-bar 0 and turning on insulated pivots p. As the governor-arms diverge the arm of the fork N" is drawn back and forces the bars 22 a into the jaws and the circuit is then complete through j, n, o, 71, and When the governors converge, the arm N returns and frees the switch, which is thrown off by the spring r.

The spindle carrying the sector It and pinion F also carries loose upon it an arm G, which acts upon a switch (l, so as to reverse the connection of the armature B with the coils Z) of the field-magnets L at the sametime that the polarity of the brushes D is reversed on the reversal of the motion of the train, the

motion of the arm G being effected by pins G on the pinion FY As before stated, the brushes E of the reghlatingalynt-nno are held stationary on the commutator l3.

As before explained, Iprefer to arrange the shunt-circuit a of the field-magnets L so that when the gen eratin g-armature is running at its highest speed this circuit will unaided give a magnetic held of the intensity proper for the required electro-motive force in the generating-arinature. In the circuit 1) the electromotive force of the accumulators should be entirely balanced by the opposing electro-motive force of the regulating-armature when running at the same maximum speed. ()n a reduction of the speed the resulting reduction of electro-motive force in the armature A will be entirely compensated for by an increase of magnetic intensity produced by the circuit b, as the opposing electro-motive force of the regulating-armatur will now be decreased to such an extent as to allow a suiiicient current from the accumulators to pass through the circuit to effect such increase of intensity.

For switching the armaturcs of the generating-machine onto the lamp or charging cireuit,I prefer to use an automatic switch K, Figs. 8 and 9, which couples up the circuitas soon as the electro-motivc force rises to the proper amount, and which breaks the circuit again when the electro-motive force falls be low the proper amount. The switch K consists of a rocking lever I, having an adjustalily-weighted tail v1: and carrying an iron armature '1', wound with a thick wire coil ii, belowwhich is an electro-magnet, the finewire coils S S of which is connected asa shunt to the dynamo circuit, so that on the produc tion of a current of a certain strength in the latter the armature is attracted in opposition to the weight It, causing the ends c c of the coil '6 to dip into the mercury-cups mm, which are connected to the leads of the main circuit, so that this circuit is now closed. The current which now flows through the coil tin increasing the polarity of the armature assists the coils S S in holding the lever down; but when the electro-motive force of the dynamo falls below a certain minimum the main current in If and the shunt-current in S S will not have sufficient force to cause the lever to be held against the weight w, (or it might be a spring,) and this consequently in overcoming the attraction will tilt the lever and cause the main circuit to be broken.

It will be obvious that any other known construction of automatic switch having similar action might be used in place of the above, and I make no claim to the said construction as part of my present invention.

Having thus described the nature of my invention and the best means I know for carrying the same into practicaleltect, I claim 1. In electric machinery for lighting railway-trains, a generating-dynamo the fieldilO magnets of which have, in addition to the ordinary shunt-wound exciting-circuit, a supplenental circuit connected to an independent source of current, and having in series with it the armature-circuit of a regulating-dynamo driven at the same speed or subject'to the same degree of speed variation ast'hegenerating-dynamo, the electro-motive force of the regulating-armature being made to oppose the electro-motive force of the independent source of current, so that its variation in proportion to the variation of speed will practically maintain constant the electro-motive force of the dynamo, substantially as described.

:2. In agenerating-dynamo for lightingrailway-trains, the combination, with the ordinary shunt exciting-circuit for the field-magnets, of a supplemental exciting-circuit connected to an external independent source of electric current and to the arrnat ure-circuit of a regulating-dynamo subject to the same'variations of speed as the generating-dynamo, the electro-motive force of lhearmature-circuit being, opposed to that of the independent source of current, so as in counteracting it"to a greater or less .legree, according to the speed of the regulating-armature, to maintain the electromotive force of the generating-dynamo practically uniform.

3. In agenerating-dynamo fol-lighting railway-trains, the combination, Wit h the ordinary shunt exciting-circuit for the field-magnets, of a supplemental exciting-circuitwhich is subject to two opposing electro-motive forces, the one proceeding from a constant'independent source of current and the other from the armature-circuit of a regulatingdynamo whose armature revolves at the same speed or is subject to the same speed variation as that of the generating-(Lynamo, so that as the electro-motive force of the regulating-armature increases with an increase of speed it will tend to neutralize the electro-motive force ot' the constant source of current, substan- C and in series with the armature of a regulating-dynamo I, driven at the same speed or subject to the same speed variation as the generating-dynamo, the last-named armature being so connected to the exciting-circuit b that'its electro-motive force acts in opposition to the electro-motive force of theindependent source of current, substantially as and for the purposes described.

5. In dynamo-electric generating machinery wherein'the armature is required to operate when revolving in either direction for efiecting the reversal of thelead of the commutatorbrushes when the direction of rotation is reversed, a friction-clutch, partot' which revolves with the armature-shaft, while the other part is attached to the brush-gear, and which operates in combination with a governor so as to be kept in gear when the shaft is stationary or revolving at a very slow speed, but which is moved out of contact by means of the governoras soon as a certain slow speed is exceeded, substantially as herein described.

'6. The combination, with a governor, of a friction-clutch for actuating the commutatorbrushes, which is moved out of gear by the governor when a certain rate of speed is exceeded, a contact device acted uponby the governor when the speed requisite for producing a certain electro-motive force is attained, so as to couple up the exciting-circuits, the governor being made to act upon the said contact device so as to uncouple the excitingcircui-ts when the speed falls below the said rate, substantially as described.

7. The combination of a generating-dynamo, a regulating-dynamo whose circuit includes a regulating-coil on the generating-dynamo, mechanism for reversing the position of the comm utator-brushes on the reversal of the motion of the armature-shaft, and a switch connected to said mechanism, so that when this reverses the position of the brushes it also reverses the connections'ot armature of the regulating-dynamo with the regulatingcoil on the field-magnets of the generatingdynamo, substantially as described.

In testimonywhereof I have signed my name to this specification, in the presence of two subscribing Witnesses, this lst day of May, A. D. 1890.

- JOHN H. HOLMES.

\Vitnesses:

PERCY CORDER, Solicitor and .Notary Public, Newcastle-upon- Tyne.

HARRY BENSON, Solicitor, 41 llfoslen St, N cwcastZc-upon- Tyne.

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