US2743377A - Electrical controller for miniature trains - Google Patents

Description

April 24, 1956 M. J. MURPHY ELECTRICAL CONTROLLER FOR MINIATURE TRAINS Filed Sept. 14, 1953 3 Sheets-Sheet l INVENTOR. Mari; J Muff/0 fa/ irrom ir April 24, 1956 M. J. MURPHY ELECTRICAL CONTROLLER FOR MINIATURE TRAINS Filed Sept. 14, 1953 3 Sheets-Sheet 2 INVENTOR. Mari; M09969 April 24, 1956 M. J. MURPHY 2,743,377 ELECTRICAL CONTROLLER FOR MINIATURE TRAINS Filed Sept. 14. 1953 3 Sheets-Sheet 3 IN V EN TOR. Mari: Maw/y Irma/vi) United States Patent 2,743,377 ELECTRICAL CONTROLLER FOR MINIATURE TRAINS Moyes J. Murphy, Monrovia, Calif. Application September 14, 1953, Serial No. 379,819

Claims. (.Cl. 3.07 -9.6)

My invention relates in general to means especially useful in controlling the speed and direction of operation of electrically driven devices, particularly miniature trains.

In one form, miniature trains are operated. by electricity supplied through the tracks which supportthe train. For example, direct current is furnished in varying amounts and in reversible polarity to determine not .only the speed of the miniature .train, but also its direction of advance. The propulsion machinery in an. electrical miniature locomotive usually has characteristics such that it does not start smoothly and easily or at a scale starting acceleration and is incapable of smooth, accurately simulated operation at or near zero speed.

It is very important, particularly. to miniature train hobbyists, to reproduce, in as precise as fashion .as possible and as nearly to scale aspossible, vthe regular operation of the prototype devices. Unfortunately, .due to the relatively high coetficient of static friction, due to stick factors and other related influences, it is at present impossible to provide .a very smooth and gradual acceleration from or to stopped condition or to operate continuously at a scale speed approximating starting. or stopping. In other words, miniature trains can not easily be operated very slowly but instead start and stop jerkily. That is true of their operation in either direction.

It is therefore an object of my invention .toprovide an electrical control for miniature trains which is capable of starting the train very gradually and to scale speed and with scale acceleration from a standing start up to a maximum velocity and down to a stopped condition.

Another object of my invention is to provide gradual acceleration of a miniature train in either direction of operation.

Another object of my invention is to provide means for controlling the speed of operation of .a miniature train gradually and smoothly over the entire range of operation.

Another object of my invention is to provide an electri'cal controller which can readily be adapted to miniature train equipment now available and in use without change thereto.

Another object of my invention is to provide an electrical controller which can readily. be operated by the usual operator without any substantial change. in his operating. technique.

Another object of the invention is to provide an electrical controller economical to manufacture, simple to service, if necessary, and which can readily be sold at a. price within the range of the miniature train market.

A still further object of the invention is to provide an electrical controller which is not adversely affected, as by overheating or the like, by protractedoperation at any speed.

An additional obj ct of the invention is in general to provide an improved electrical controller for miniature trains.

Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings in. which:

Figure l is an isometric view, portions being broken away, showing the electrical controller in its normal position of use in connection with a miniature train.

Figure 2 is a plan of the controller, a portionof the housing being broken away to disclose the interior.

Figure 3 is a cross section, the plane of which is indicated by the line 3-3 of Figure 2.

Figure 4 is a cross section, the plane of which :is indicated by the line 44 of Figure 3.

Figure 5 is a view showing the various layers of the arm before assembly.

Figure 6 is a view similar to- Figure 4 with certain portions removed for clarity and showing the arm in one extreme position of operation.

Figure 7 is a diagrammatic plan of the rotary commutator illustrating various brush positions thereon.

Figure 8 is an end view of the electrical controller.

While the electrical controller of my invention is adapted for use in many fields for controlling electrical equipment, it is especially adapted for the control .of miniature trains and. is therefore described in that connection. In the usual instance, the miniature train includes a locomotive 6, for example, which is provided with any suitable sort of electric motor, in the present instance, the motor being a direct current motor. The locomotive 6 operates on a miniature track 7, having metallic conductor rails 8 and 9 included therein The rails are insulated from each other by miniature ties 1.0 and serve, by connections in the locomotive 6, as .condoctors to supply electricity to the driving motor for the locomotive, the polarity of ,the rails '7 and .8 being reversed in order to reverse the motor to act as a brake or to run in the opposite direction.

Supply of current ,to the rails 7 and 8 is through a pair of conductors 12 and 13, emanating from an electrical controller 14 constructed in accordance with the invention. The controller 14 is supplied with current of two sorts. T ere is a supply of alternating current through leads 16 and 17, this current customarily being supplied at approximately to volts, and having a standard frequency, for example, 60 cycles per second. The conductors 16 and 17 have leads 18 and 19 extend ing to a suitable current rectifier 21 for affording a supply of direct current through leads 22 and 23 to the electrical controller 1.4. If desired, the rectifier 21 .can be replaced by .a storage battery or any other suitable source of direct current supply, in which instance the leads 18 .and 1 9 are omitted. In any case, the electrical controller 14 is supplied with alternating. current through the leads l6. and 17 and is supplied with direct current through the leads 22 and 23. The voltage andamperage of the direct current supplied through the leads 22 and 23 are preferably those customarily utilized for the operation of the miniature locomotive 6.

The controller housing 14 preferably incorporates a top panel 31, of non-conducting material, on which a frame 32 is mounted. The frame preferably includesa mounting plate 33 and a top plate 34, together constituting a cover, and secured in. juxtaposition with an intervening sound absorbent .and cushioning. material in the form of an interposed sheet 36. The top plate 34. is .pro.- vided with a number of apertures 37 through which access is had. to fastening screws 38: for securing the frame '32 to the housing 14. The cover is held together by frame posts 39- and appropriate fastenings 41 so that an appropriate mounting is afforded.

The'depending posts 39, four in number, at their lower endsserve as supports'for a-frame plate 42 secured in positionby fastenings 43. At one extremity, the frame plate 42 is extended to serve as a mounting for insulating layers 44 and 46, held in position with respect to apertures through the frame plate 42' by bushings 47 formed integrally with insulating tubes 48 upstanding from the frame plate 42. Of-the four insulating tubes 48, the outer two are secured in position by through bolts 49 and 51, having fastening nuts 52 securing them in position, and also having jam nuts 53-to act as terminals for the conductors 22 and 23. One of the two central members 48 is longer than the others and the two are-held in position by through bolts- 54 and 56 having jam .nuts 57 and lock nuts 58 thereon to serve as terminals for the conductors 12 and 13.

Also mounted on the .top plate 34, for rotation with respect thereto, is a shaft 61 having a sleeve 62 secured thereto by a through pin 63. A hub 64 with an extended bushing thereonfits overthe shaft 61 and is jammed against the sleeve 62, except for an-intervening anti-friction washer 66, by an axial screw 67. A set screw 68 prevents rotation of the hub 64 with respect to the shaft 61. Also jammed in good supporting relationship with the top plate 34, is an intervening friction washer 69 and the central ring 71 of an operating lever 72. The lever 72, at the ring portion 71, is preferably secured by brazing, silver soldering or the like, to the hub 64 and is upwardly offset so as to be spaced a convenient distance from the top plate 34. It ends in a handle portion 73 including a through finger aperture 74, having rounded edges. With this construction, the lever 72 can be swung with respect to the cover about the axis of the shaft 61, the washers 66 and 69 serving not only to assist in the mounting but as friction supports so that the lever is easily rotated or swung, yet will stay in any set position.

The sleeve 62 depends through the housing 14 and carries a stub shaft 76 for rotation therewith, the fastening being effectuated by a pin 78. The stub shaft 76 is axially bored to receive an electrical brush 79 urged in a downward axial direction by a coil spring 81.

Also carried by the stub shaft 76 is a packet of layers constituting an arm 82. The top layer 83 of the packet is a metallic conductor and is secured by brazing, soldering or welding to'the stub shaft 76. Immediately beneath the layer 83 is a pair of insulating layers 84 and 86 and below them is a conducting, lower layer 87. All of these layers are of substantiallythe same outline contour, as shown especially in Figure 4, and constitute substantially a circular disc with a radial projection. The packet is mechanically secured together with the upper layer 83 electrically insulated from the lower layer 87 by fasten ings 88 which alternately engage the lower and upper layers but invariably engage the intermediate insulating layers 84 and 86. The fastenings are spaced from the layers they do not contact by apertures 89 therein of adequate insulating dimensions. Furthermore, the lower layer 87 has a central aperture of suificient dimension to be electrically separate from the stub shaft 76. Also, the insulating layers 84 and 86 have large central apertures for convenience in assembly and to avoid the fillet left by the welding or brazing operation around the stub shaft 76. Even further, while the various layers in the packet are of the general conformation indicated, the lower layer 87 is somewhat incomplete in that it stops just short of a diameter on the axis of the stub shaft 76, as shown in Figures 4 and 5, and is supplemented by a co-planar extension layer 91. This completes the envelope contour but itself stops somewhat short of a diameter to leave what amounts to a diametrical groove 92 or gap in the lower surface of the arm, a portion of the insulating layer 86 being thereby exposed.

The radially extended portion of the arm carries a.

brush 93 mounted in a socket 94 of conducting material and carrying a spring 96 urging the brush 93 outwardly. The socket 94 is shouldered and grooved to receive a fastening ring 97 on its lower end and to confine an insulating disc 98 near its center. The upper layer 83 is 4 provided with an aperture suificiently spaced from the socket 94, guided by the close fitting insulating layers 84 and 86, so that there is no electrical contact between the upper layer 83 and the socket 94. There is, however, a close metallic contact not only between the socket 94 and the lower layer 87, but also between the fastening ring 97 and the socket so that a firm electrical connection is so established between the brush 93 and the lower layer 87.

Carried on the frame plate 42 in operative relationship with the brushes 79 and 93 is a rotary commutator 101. This, preferably, is in the form of a disc 102 of metal over which an insulating sheet 103 is disposed. Superposed on the insulating sheet is a conducting metallic disc 104 of generally circular outline, having, however, two tangent circular apertures 106 and 107 (Figure 6) cut therefrom. In the apertures are disposed two insulating discs 108 and 109 secured in position by fastenings 111 insulated from but secured in the disc 102, while similar fastenings 112 hold the conducting disc 104 in position. The disc 102 is formed with a central hub 113 fitting over a drive shaft 114 and secured thereto by a set screw '116.

The drive shaft 114 is rotated by means of an electric motor 117 of any customary kind and usually is an alternating current, synchronous motor with or without a gear reduction to give any desired speed of operation of the shaft 114. In the present instance, the speed of rotation is of the order of 3,600 revolutions per minute.

.The motor is supported on the plate 42 by appropriate fastenings 118 and is connected to insulated terminals 119 and 120 serving as the terminals for the conductors 18 and .19, respectively.

One of the electrical paths through the structure is from the conductor 22 to the terminal 24 and through the bolt 49 to a spring primary contactor 126 secured thereto and extending approximately tangent to the arm 82. The contactor has a spherical end 127 adapted to be seated in the groove 92 when the arm is in the position illustrated in Figure 4, for example. In that position of the parts, the primary contactor 126 is against insulation and the circuit is interrupted. If the arm is moved in either direction, however, the current then has a path into either the lower layer 87 or the extension layer 91. Whichever layer forms thepath of the current, the other plate is then in touch with another primary contactor 128 having'a similar spherical end 129 thereon and being fastened to the bolt 51.

The extension layer 91 is contacted by a secondary contactor 131 on the bolt 56 and having a spherical end 132 thereon and identical in shape with the primary contactors 126 and 128 except that it is folded over to touch the smooth periphery of the extension layer 91. A similar secondary contactor 133 is supported on the terminal 54 and has a spherical end 134 in abutment with the top layer 83 of the arm. If, therefore, a circuit is completed between the lower layer 87 and the upper layer 83, the. various primary and secondary contactors and the extension plate 91, there is provided a polarity reversing device. Thus, by manipulation of the lever 72, if the terminal bolts 49 and 51 are respectively positive and negative, the terminal bolts 54 and 56 can be made respectively positive and negative or negative and positive. Hence, the polarity of the direct current supplied to the tracks 8 or 9 is selected and reversed and the direction of operation of the engine 6 is established and changed. Intermediate the direction changing positions is a neutral, or zero current, or off position.

Current from the bottom layer 87; for example, is conducted to the brush 93 and in the central position of the arm 82, is blocked from further travel since the theoretical point contact of the brush 93 is exactly at the theoretical point of intersection of the tangent insulating discs 108 and 109 and so there is no current path. Since in practice the brush 93 has a small area of contact rather'than the theoretical point contact, the insulating discs 108 and 1 09 are made not exactly tangent :but interfere slightly so that there is established an off or neutral area.

When the lever 72 and the arm:82 are swung to .either side of central position, then the brush 93 is swung into the path of contact of part of the conducting disc 104. Current flows then through that disc to the brush '79, which is always in contact with the -continuous metallic periphery or marginal portion of the disc 104. The current then flows through the stub shaft 76 into the upper layer '83 and'to the secondary contactor 133. Thus, the circuit is completed, although it is completed in the reverse direction in the event the primary contactor 128 happensto :be in abutment with the layer 87 and the primary contactor 126 is in abutment with the extension layer 91.

In the operation of the device, both of the circuitsare energized so that the electric motor 117 rotates the disc 102 at a rapid rate. When the lever 72 is in a central, oil? or neutral position, the circuit is interrupted with the spherical ends 127 and 129 of the primary contactors 126 and 128 in an insulated position and also with the brush 93 in an insulated position.

In the event it is considered that it is not necessary to have an electrical gap at the ends of the primary contactors 128 and 126 when the groove 92 is in the central position, then the proportions of the groove 92 can be made such that the springy primary contactors and their spherical ends serve with the groove and the adjacent layers as a detent mechanism, yieldingly centralizing the lever 72 and the arm 82.

In either case, the brush 93, in its central position, is out of contact with an electrical conductor. However, as the lever 72 is swung to one side or the other, as shown especially in Figure 7, increasing amounts of electrical conductor abut the brush. as it leaves center position. Current flow is possible just after the brush 93 leaves central position in either direction, the duration of current flow for each revolution of the commutator 101 depending upon the displaced position of the arm 82. Toward the center, only a small fraction of one revolution is given over to current conduction, the remaining part of the revolution being a current interruption as the brush 93 rides over the insulating discs 108 and 109.

As the brush swings farther and farther away from center position, the amount of conduction time is increased and the amount of insulation time is decreased until the brush gets near the marginal periphery of the disc. There it runs on a continuous conducting portion of the disc 104 and there is no interruption at all. There is thus provided a variation in current impulse length per revolution of the commutator from zero at the center through very short impulses near the center, through increasingly long impulses toward the edge, until finally at the edge there is no interruption whatsoever but there is continuous conduction.

The particular characteristics or proportion of current fiow time to current interrupted time for any displaced position of the brush depends upon the shape of the insulators 108 and 109. These are conveniently made circular discs, although they can be segments or other configurations. There is thus provided a structure giving a variation from no impulses, tluough current impulses of varying duration to continuous current at the control of the operator. The current impulses are available and effective in either direction of operation, due to the operation of the polarity reversing mechanism.

The operator, by putting his finger on the lever 72 in or near the aperture 74 and by swinging the lever either way, to the right or to the left, can control the direction of operation of the train 6 and by controlling the amount of displacement of the lever from central position can control the speed of the train very accurately. In fact, the impulses are of sufiicient strength when they are flowing to :break loose or overcome the stick point or static friction of :the train and its driving motor, but are of sufliciently short duration .or are spaced sufficiently far apart so that the net speed of the train 6 is very small and is according to scale. It is therefore possible tostart the train smoothly and to accelerate it very slowly in accordance with accurate scale performance up to its maximum speed when there is no longer any current interruption. Similarly, the train can be braked and slowed down very smoothly and continuously to a smooth stop without jerk, and this from either direction of operation at maximum speed. In a practical example, with ;a locomotive and tracks of approximately actual size -("?HO gauge) it is possible to operate a locomotive, at an actual speed .of advance of one-quarter inch per minute, which is equivalent to a scale speed of mile per hour. The appearanceof the operation is of-continuous motion, despite the fact that the impulses are separated for part :of the time, because of the effect of momentum of the locomotive 6, and because the impulses are of quite rapid frequency.

What is claimed is:

1. An electrical controller for miniature trains comprising a frame; an arm; means for mounting said arm on said frame for swinging movement about an axis; a pair of brushes on said arm, one of said brushes being on said axis; a rotary disc commutator on said frame in contact with said brushes; said commutator having a peripheral continuous conducting portion, a central continuous insulating portion and an alternately conducting and insulating portion; means on said frame for rotating said commutator with said continuous conducting portion in contact with said one of said brushes; means on said arm for insulating said brushes from each other; and means for swinging said arm to move the other of said brushes over said various commutator portions.

2. An electrical controller for miniature trains comprising a frame; a disc commutator on said frame; said commutator having a peripheral continuous conducting portion, a central continuous insulating portion and an alternately conducting and insulating portion; means on said frame for rotating said commutator about a rotational axis; an arm; a pair of brushes on said arm; means on said arm for insulating said brushes from each other; and means for mounting said arm on said frame for swinging movement about one of said brushes as a center and with said one brush in contact with said continuously conducting portion and with said other brush swinging over said rotational axis in contact with said commutator.

3. An electrical controller for miniature trains comprising a frame, a rotary disc commutator on said frame, said frame having a plane conducting surface continuous around the periphery of said disc and interrupted in part by an insulating surface extending across the rotational center of said commutator and varying in circumferentially measured dimensions at varying radially measured distances from said center, means on said frame for rotating said commutator about said center, an arm, means for mounting said arm on said frame for swinging movement in a plane parallel to the plane of said disc and about an axis within the periphery of said disc, a first brush on said arm disposed on the swinging axis of said arm and extending into abutment with said continuous conducting surface, a second brush on said arm disposed to swing through a position coincident with the rotational axis of said disc and extending into abutment with the surface of said disc, and means on said arm for insulating said first and second brushes from each other.

4. An electrical controller for miniature trains comprising a frame, a disc commutator on said frame, said commutator having a peripherally continuous conducting surface interrupted in part toward the center of said disc commutator by an insulating surface, means on said frame for rotating said commutator, an arm, a pair of brushes on said am, means on said arm for insulating said brushes from each other, and means for mounting said arm on said frame for swinging movement parallel to the plane of said disc commutator, said mounting being in a location to dispose one of said brushes for continuous contact with said peripherally continuous conducting surface and the other of said brushes for contact alternately with said peripherally continuous conducting surface and said insulating surface.

5. An electrical controller for miniature trains comprising a frame, a disc commutator on said frame, said commutator having a planar continuous conducting surface interrupted in part by an insulating surface extending across the rotational center of said commutator, means on said frame for rotating said commutator, an arm, a pair of brushes on said arm, means on said arm for insulating said brushes from each other, means for mounting said arm on said frame for swinging movement with one of said brushes in contact with said continuous conducting surface and the other of said brushes in contact with said surfaces and passing over the rotational center of said commutator, means for including said commutator conducting surface and said brushes in an electrical circuit, first polarity reversing switch contacts for said circuit and disposed on said arm, second polarity reversing switch contacts for said circuit and disposed on said frame, and means for abutting said first switch contacts with said second switch contacts for one polarity when said arm is on one side of said rotational center and for abutting said first switch contacts with said second switch contacts for the other polarity when said arm is on the other side of said rotational center.

References Cited in the file of this patent UNITED STATES PATENTS

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