US2020398A - Electromagnetic regulating apparatus - Google Patents

Description

Nov. 12, 1935. AH. CHILTON ELECTROMAGNETIC REGULATING APPARATUS Filed Aug.- 3, 1933 4 Sheets-Sheet l ELECTROMAGNETIC REGULATING APPARATUS Filed Aug. 3, 1933 4 SheetsSheet 2 Nov. 12, 1935. v A H, CH|LT0N 2,020,398

ELECTROMAGNT I C REGULATING APPARATUS Filed Aug. 3, 1933 4 Sheets-Sheet 5 Nov. 12, 1935.

4 Sheets-Sheet 4 Filed Aug; 5, 1955 is l 0 Z .a L. l I /QV n 6 I y mlnu,A M W W, 6 4 u.. 4 L; .d w mv la Patented Nov. l2, 1935 UNITED STATES PATENT AOFFICE ELECTROMAGllE-TEC REGULATING APPARATUS Application August 3, 1933, Serial No. 683,557 In Great Britain January 28, 1933 8 Claims.

This invention concerns improvements in or relating to electro-magnetic regulating apparatus and is more especially concerned with socalled carbon pile regulators such as are commonly employed, for example, in lighting installations on railway vehicles.

In a regulator of this kind, it is necessary that the electro-magnetic actuating force, the reaction of the carbon pile, and the force of the usual spring or equivalent loading means should be balance over the range of operation of the regulator. As the reaction of the pile, which va,- r'ies according to a given law, is a relatively small component, the required balance involves the l5 matching of the torque movement characteristic of the electro-magnetic actuating device against that of the spring or other loading means. Thus, if the characteristic of the electro-magnetic device is of a complex or curved nature, as has hitherto been the case, a relatively-complicated spring compensation system is required to provide a characteristic that can be matched with it.

The principal object of the present invention is to provide a magnet system having a characteristic of a shape substantially conforming to a part of a sine curve, particularly that part thereof which is nearly a straight line. Such a magnet system can be readily matched with a relatively simple spring system. With this object in view according tothe present invention use is made of a magnet system with a rocking rotor whereof the faces which come opposite the pole-faces of the magnet in the attracted position of said rotor are of circular shape.

Thus the magnet system may comprise a rotor wholly or in part of substantially circular crosssection mounted so as to be capable of rocking about a diametrical axis at the mid-point of its length and a magnet having opposed pole-faces between which the rotor is arranged to rock, said faces being of a concave cylindrical profile concentric with the aforesaid axis of the rotor and the rotor-ends being of convex cylindrical prole also concentric with said axis. The said polefaces are preferably of rectangular shape. A magnet system of this nature has a declining characteristic of the aforesaid required shape over a large range of movement of the rotor, i. e.

from an initial position in which the leading tips of the rotor almost overlap, or slightly overlap, the adjacent tips of the pole-faces to a nal position in which the rotor is located between the pole-faces. As a consequence, the magnet system can be readily matched with a spring system consisting essentially of a simple spring acting upon the rotor through a plain crank arranged so that the lever arm decreases as the rotor is attracted into the magnet.

Two embodiments of the invention will now be 5 described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a rear elevation of a carbon pile regulator intended more especially for dynamo regulation purposes in train lighting installations, 10

Fig. 2 is a Vertical section thereof.

Fig. 3 is a front elevation of a carbon pile regulator intended more especially for lamp voltage regulation purposes in train lighting installations, and 15 Fig. 4 is a vertical section thereof.

Referring rst of all to Figs. l and 2, the various component parts of the regulator are mounted upon a frame I. The iron magnet core 2, which is of approximately inverted U-shape and car- 20 ries the exciting winding or windings 3 upon its yoke portion, is carried in a foward extension 4 of the frame I. Supported in ball bearings 5 in the main frame I and forward extension 4 is a spindle 6 carrying an iron rotor 1 located be- 25 tween the opposed pole-faces 8 of the magnet core. These pole-faces are of a concave substantially cylindrical profile (Fig. l) concentric with the axis I0 of rotation of the rotor and' of rectangular shape, as shown in Fig. 2. The 30 convex end-faces II of the rotor are also of cylindrical profile struck from the axis I0. Consequently, when the rotor 1 is in the attracted position (Fig. 1) in which it extends between the pole-faces 8, the air gaps between said pole- 35 faces and said rotor end-faces are of uniform width. The rotor 1 is a cylindrical body of uniform circular shape. With this arrangement it is possible to provide a magnet system having a declining characteristic of a shape substantially 40 conforming to a part of a sine curve, particularly that part thereof which is nearly a straight line.

An overhanging extension of the spindle 6 on the rear side of the frame I carries a disc I6 45 and. a crank I1. The latter is connected by a crank-pin i8 to a push rod IS carrying a compression plate 20. The pile ZI of thin carbon discs is arranged between the plate 20 and a top plate 22 having an upward extension 23 which isvcon- 50 nected by a pivot 24 to a bracket 25. This bracket is mounted upon the top of the frame I in a vertically adjustable manner by means of a screw v 26 with a grooved head 21 engaged by the forked end of said bracket and is locked in position by 55 means of a screw 28 passing through a slot 29 in said bracket. Insulated pins 36, dependent from the plate and car" a plate 3l through a hole in which the rod freely passes, constitute a cage in which the pile guided with a slight degree of freedom. A practically vertically disposed helical tension spring of substantial length is connected between a metal tape 33, which is anchored to the disc l5 between slightly curved blocks 34 preventing too sharp flexure of the tape and an adjustable attachment means 35 which is substantially identical with that of 25-21 for the pile. The disc l which may be mutilated as shown, also carries crank-pin 35 connected with a dash-pot 3l.

The point of attachment of the tape 33 to the disc l is somewhat to side of 'the bottom dead centre thereof. As .ne rotor 1 moves between the pole faces 13 fr n its initial position, in which its longitudinal airis lies .as indicated by a chain line in Fig. towards the end position illustrated in Fig. l, the point of attachment travels towards the dead centre so that the effective lever arm with which the spring 32 acts upon the rotor decreases. In the range of operation of said rotor, however, said point never reaches the dead centre. It will be appreciated that the characteristic of this spring system is determined practically wholly by the variation of the lever arm with which the spring acts, said spring itself suffering only a relatively small elongation and contraction. Since, however, the lever arm variation, which is governed by a sine curve law, corresponds to that short length of the sine curve which is practically a straight line, it follows that the spring system has ,a declining characteristic which can be readily matched with that of the magnet system. The adjustable attachment means 25E- 2Q and 35 permit of adjustment of the initial compression and tension respectively in the carbon pile and spring. The manner of operation oi such a regulator is well lmown and need be only brieily referred to: With increasing excitation of the magnet winding or windings connected for example across the dynamo to be regulated, the rotor 1 tends to be attracted from its initial position (see the position of the axis as indicated by a chain line in Figure l) towards the final position illustrated in Figure this movement being resisted by the spring The said rotor movement, translated through the push rod I8 and plate 2f] results in the decompression of the carbon pile The resultant increase of the resistance is utilized for regulation purposes by, for instance, lisposing the carbon pile in series with the field windings of the dynamo to be regulated. The dash pot 31 counteracts tendency'towards jerking or huntinfr action of the regulator.

As regards the magnet system, the lamp voltage regulator illustrated in Figures 3 and 4 is es sentially similar tc that previously described. The disposition of the spring .and the carbon piles and the means for their control are, however, somewhat diierent. The disc IE and crank l1 are not mounted directly upon the rotor spindle ii but upon a separa-te spindle 61 disposed vertically below it. The two spindles E and 61 are geared together by a flexible metal tape 38 which is wrapped over arcs of the rims of the disc I6 and a disc 3Q on the spindle 5 (Fig. 3). The tape is anchored to the disc '5S at 4D and to the disc l5 by an adjustable anchorage del. The diameter of the disc EG is larger than that of the disc 39 so that the angular movement imparted to the former by the latter is smaller than the angular movement of the rotor 1 but is proportional thereto. With such an interposed gearing, the range of angular movement of the rotor is not unduly restricted, even if it is desired to keep the angular movement of the spring anchorage 34 within a range corresponding to the straight line portion of the sine curve.

The three carbon piles 4I provided to carry the lamp current are mounted above the magnet system upon a separate platform 42 secured to the frame l. In place of the push rod 9 of Figures l and 2, use is made of a push rod 43 ccnnected by a. see-saw lever 'lfl to a pull-rod 45 around which the piles 4! are grouped. This -rod 45 incorporate length-adjustment device which takes the i a turnbuckle 46 but is designed to give a nner adjustment than an ordinary turncucl i. The turnbuckle 48 has et the two ends threads of the same sense but of somewhat di ment pitch. Such a device provides a very fine adjustment as the effect of the eads is differential, i. e, for one turn of c, the length adjustment is equivalent only to the diierence between the pitches of the two threads. The pull rod 45 acts upon the carbon piles 4! through an equalizing spider 41 having a part spherical socket engaged by a part spherical head 4S on the rod 45.

The carbon piles 4l, when in use, experience a considerable rise of temperature with attendant expansion which, unless compensated for, may seriously derange the precision of the regulator. According to a further feature of the invention. a compensating evice for this purpose comprises a ring 50 of a material which expands with rise of temperature, a number of spokes 5| of a materia-l with a relatively low or negligible thermal expansion, such as mild steel or nickel-steel alloy, and a hub 52, the spokes being arranged at an angle of inclina-tion to the plane of the ring. This device is shown interposed between each carbon pile and the edualizing spider 41. The ring 50 which is of a material, for example aluminium, of good conductivity and not too large heat capacity so as to respond readily to temperature changes in the pile, is mounted upon the pile with the interposition of the usual metal contact piece and an insulating disc or washer. The hub 52 is connected pivotally with the spider 41, said hub being extended upwardly and the extension divided by a, diametrical slot, whilst holes for a pivot pin 53 are drilled at right angles to the slot. The effect of this compensating device is as iollcws: The ring 55' will follow the temperature rise of the carbon pile 4i and will expand in diameter. The spokes 5i on the other hand, will expand little or not at all so that their inclination will decrease, causing a decrease in the depth of the device between the hub 52 and ring 50. The size of the ring and initial inclination of the spokes is designed so that the decrease in depth of the compensating device substantially counterbalances the increase in length of the carbon pile itself over a suilicient range of temperature variation. In order to permit of the variation of the inclination ci the spokes 5I, these may be made of relatively flexible wire, a sucient number of spokes being provided to take the maximum pressure exerted on the pile.

The manner of operation of such aI lamp voltage regulator is well known and requires no detailed description here. The mest usual arrangement is that the magnet Winding 3 is subject to the lamp voltage whilst the carbon piles 4I con- 75 stltute a resistance in series with the lamp load. The separate piles are connected in parallel with each other. Upon the lamp voltage tending to rise, the regulator acts to relieve the pressure upon the piles and thus to increase their resistance and so maintain the voltage upon the lamps themselves constant. The initial setting of the regulator is effected by the adjustment means 35, 401 and 46.

I claimt- 1. In electro-magnetic regulating apparatus, particularly a carbon pile regulator for use in train lighting installations, the combination of a magnet system comprising a magnet with pole faces, and a rotor mounted so as to be capable of rocking in relation to the pole end-faces, the faces of the rotor which come opposite to said pole faces in the attracted position of said rotor being of substantially circular shape when viewed endwise and a spring system connected to the said rotor and adapted for exerting thereon a torque which opposes the magnet attraction and varies inversely with the rotor movement in an approximately rectilinear relationship.

2. In electro-magnetic regulating apparatus, particularly a carbon pile regulator for use in train lighting installations, the combination of a magnet system comprising a magnet with dlametrically opposed pole-faces, and a rotor of substantially circular cross-section mounted so as to be capable of rocking about a diametrical axis at the mid-point of its length and between the opposed pole faces, said pole faces being of a concave cylindrical prole concentric with said axis and the rotor ends of convex cylindrical profile concentric with said axis and a spring system connected to the said rotor and adapted for exerting thereon a torque which opposes the magnet attraction and varies inversely with the rotor movement in an approximately rectilinear relationship.

3. In electro-magnetic regulating apparatus, particularly a carbon pile regulator for use in train lighting installations, the combination of a magnet system comprising a magnet with pole faces of rectangular shape, and a rotor mounted so as to be capable of rocking in relation to the pole faces, the end-faces of the rotor which come opposite to said pole faces in the attracted position of said rotor being oA substantially circular shape when viewed endwise and a spring system connected to the said rotor and adapted for exerting thereon a torque which opposes the magnet attraction and varies inversely with the rotor movement in an approximately rectilinear relationship.

4. Electro-magnetic carbon pile regulator,

comprising a magnet system with a rotor of substantially cylindrical shape rockable about an axis perpendicular to the cylinder axis, a carbon pile operatively connected to said rotor, a tension spring extended at a substantially constant tension, and a simple crank member operatively connected to said rotor, the tension spring being connected to said crank member at a point in the vicinity of its dead centre position, which point, upon the rocking of the rotor in the direction of attraction, moves towards the dead centre position.

5. Electromagnetic carbon pile regulator, comprising a magnet system with a rotor of substantially cylindrical shape rockable about an axis perpendicular to the cylinder axis, a carbon pile operatively connected to said rotor, a tension spring exerting a substantially constant tension, a crank member to which said spring is attached at a point in the vicinity of its dead centre position, reduction gearing between the rotor and crank member such that the latter performsa movement proportional to but smaller than that of the former, the aforesaid point of attachment being so located that, upon the rocking of the rotor in the direction of attraction, it moves towards the dead centre position.

6. Regulating device for a train-lighting installation comprising an electro-magnet of substantially U-shape with pole pieces facing each other, a rotor of cylindrical shape mounted to rock about a diametrical axis. between said pole pieces, a spring exerting a substantially constant tension, a carbon pile operatively connected to said rotor for control thereby and a simple crank member connected to said rotor and having the spring attached to it, said crank member being arranged so that it moves towards its dead centre position upon attraction of said rotor by said magnet.

Ikl. In carbon pile regulator, a pile assembly comprising a carbon pile, an abutment for said pile, pile-compressing means, and temperature compaV sation means consisting of a hub, a ring o1 material which expands with rise of temperature and a number of spokes which are made of a material with a relativen7 low thermal expansion and are connected, at an angle to the plane of the ring, between the latter and the hub, said ring and hub being interposed between and in abutting relationship with adjacent parts of the pile assembly,

8. In a carbon pile regulator, a magnet system comprising a magnet having pole faces, and a rotor mounted so as to be capable of rocking in relation to the pole faces, the end faces of the rotor which come opposite to said pole faces in the attracted position or said rotor being of substantially circular shape when viewed endwise, and a spring system connected to said rotor and capable of exerting thereon a torque in opposition to the magnet attraction, the said spring system torque varying in a relationship which follows that part of a sine curve which approximates a straight line.

ALFRED HENRY CHILTON.

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