Nov. 2, 1971 A. s. VALLS 3,616,761'
' HOMOPOLAR LOCOMOTIVE RAILWAY Filed .my 1e. 196s 50 IN1/wrox u 55A? To afee@ Inv/Q l 3,616,761 HOMOPOLAR LOCOMOTIVE RAILWAY Alberto Serra Valls, Apartado 1827, Caracas, Venezuela Filed July 16, 1968, Ser. No. 745,166 Int. Cl. B61b 13/00; B61c 9/46; H02k 31/02 U.S. Cl. 104-148 R 12 Claims ABSTRACT OF THE DISCLOSURE A direct current propulsion system for homopolar electric locomotive railways wherein driving current is delivered to self-contained motor-wheel assemblies through the track rails. Each motor-wheel assembly consists of a spiral homo-polar winding mounted between a pair of circular discs of magnetic material. A magnetic housing member carried by the vehicle -frame extends adjacent the peripheries of the discs and provides a flux path therebetween. Electrical contact `with the associated rail is made to the winding at its peripheral end and its inner end is connected through an electromagnetically-operated control switch to the internal end of the winding of the opposite motor-wheel assem-bly. The two cooperating wheel assemblies and the control switch are coaxiallymounted on, but are insulated from a common axle. The switch control winding is rigidly-secured to the 'vehicle frame surrounding a pair of concentric arcuate contact segments secured on and insulated from the axle. A bridging ring is drawn into conductive engagement with the segments responsive to the energization of the control winding.
This invention relates to propulsion systems for electric railways, and more particularly to a system employing self-contained combination motor and wheel assemblies wherein each assembly includes an electric motor of the homo-polar type.
A main object of the invention is to provide a novel and improved propulsion system for electric railways which involves relatively simple components, Iwhich provides highly efficient operation with minimum mechanical and electrical losses and which minimizes current transmission costs by employing the rails as conductors for the required driving power.
A further object of the invention is to pro'vide an improved electrical propulsion system for railways of the type employing self-contained motor-wheel assemblies making direct conductive contact with the track rails, the system thereby avoiding the necessity of employing collector brushes or rings, providing an assembly requiring a minimum number of parts, and being easy to maintain in proper working condition.
A still further object of the invention is to provide an improved railway propulsion system which eliminates the necessity of employing a special traction engine, which provides etiicient and economical distribution of electric driving power, which employs components which are relatively light in weight and small in bulk, and which avoids electrical losses heretofore caused by commutation.
A still further object of the invention is to provide an electrical propulsion system for railways wherein driving torque is developed directly in the wheels without any need for transmission or lubrication, Iwherein control of velocity of the associated vehicle is accomplished in a simple, inexpensive and effective manner, and wherein the components are economical to manufacture and `durable in construction.
A still further object of the invention is to provide an improved electrical propulsion system for railways of the UnitedV States Patent O 3,616,761 Patented Nov. 2., 1971 lice the cars of an electric railway system according to the present invention, showing the construction of a pair of cooperating opposite motor-wheel assemblies and their associated electro-magnetically-operated control switch.
FIG. 2 is a fragmentary transverse vertical crosssectional 'view taken substantially on the line 2-2 of FIG. 1. t. FIG. .3 ista fragdrnentary transverse vertical cross-seciona View, o a re uced scale, take une 3 3 of FIG. 1. n substantially on the Referring to the drawing, 11, 11 designate opposite depending vertical portions of the framing of a railway car employing an improved propulsion system according to the present invention. The car framing elements 1K1, 11 are mechanically-supported on and carried by a plurality of wheel and axle assemblies, presently to be described which, 1n turn, are supported on and roll along -a pair of track rails 12 and 13 which also serve as electrical conductors to ydeliver driving power to the car in a manner presently to be described. The rails 12 and 13` are suitably-supported on and are insulated from conventional railway ties 14, the rails lbeing insulated yfrom the ties by suitable blocks 15 of insulating material located between the bottom langes of the rails and the ties.
The car is provided with a plurality of spaced driving wheel and axle assemblies, one of which is designated lgenerally at 17 in FIG. l. i
The typical wheel and axle assembly 17 comprises a transverse axle 18 having reduced end portions 19 19 which are respectively journaled in the lower portions of the depending side members 11, 11 by means of suitable ball bearing assemblies 20, 20, with the intermediate reduced portions 21, 21 on which are mounted respective motor-wheel assemblies designated generally at 22 and 23, .of similar construction. The assembly 22 comprises an inner disc member 24 of magnetic material and an outer disc member 25 also of magnetic material mounted on the axle reduced portion 21 and insulated therefrom by means of an insulating sleeve 26 suitablysecured on reduced portion 21. Thus, the sleeve 26 may be clampingly-engaged by a retaining nut 27 threadedly-engaged on the axle end portions between the reduced segments 21 and 19, as shown in FIG. l. The inner disc member 24 is formed with a peripheral guide flange 28 cooperating with the subjacent rail head in a conventional manner.
Clampingly-secured between the disc members 24 and 25 is a spiral winding 29 whose outer end is connected to a contact ring 30 Hush with the peripheral tread Surfaces of the disc members 24 and 25. Respective insulating discs 31 and 32 of suitably impregnated paper, or any other suitable insulating material, are clampinglysecured between the opposite side surfaces of the spiral coil 29 and the magnetic disc members 24 and 25. From FIG. 1 it will be readily apparent that the track ring 30 makes electrical contact with the rail 12, whereby the outer end of the spiral coil 29 is electricallydconnected to rail 12 to receive current therefrom.
Rgidly-secured to the sidewall 11 is a housing member 33 of magnetic material which closely embraces the upper portion of the assembly 22 although being spaced therefrom by a Very small peripheral air gap 34, Since the disc members 24 and 25 and the housing member 33 are of magnetically-permeable material, they define a magnetic stator structure wherein magnetic flux can circulate through the turns of the spiral-wound coil 29, the ux being generated responsive to the ow of current through the coil, as will be presently described. For example, as shown by the arrows in the upper portions of the disc members 24 and 25 and in the housing 33, in FIG. 1, the flux may circulate in a clockwise direction, whereby it can interact with the turns of the spiral-wound coil 29 and produce torque in acordance with the well-known manner of operation of a homopolar motor. The magnetic flux llows radially in the disc 24 and 25 and crosses the air gap 34, flowing through the housing 33, which thus constitutes a magnetic yoke with respect to the disc members 24 and 25. In order to decrease the reluctance of the air gap 34, the peripheral portions of the discs 24 and 25 are preferably somewhat enlarged, as shown at 35 and 36. The spiral winding 29 may be formed in any suitable manner, for example, from a metal disc cut in spiral form. As above-mentioned, the electric current passing through the coil produces a magnetic tield in the spiral coil which, in turn, interacts with the current, producing a torque which forces the coil to rotate on its axis. The direction of the torque does not change when the direction of the current flow is changed, because the magnetic field is also reversed when the current is reversed. Thus, the direction of rotation of the wheel assembly depends exclusively on the direction of winding of the spiral coil 29.
The dynamic characteristics of a motor of the type above-described are similar to those of a motor of the series type, because the intensity of the magnetic eld is directly proportional to the intensity of the current in the rotor winding.
The respective motor-wheel assemblies 22 and 23 are connected in series and are arranged to produce torques in the same direction responsive to their energization by a current owing through the spiral windings of the assemblies, said current being supplied by the rails 12 and 13. Thus, the spiral winding of the assembly 23 is energized from a conductor 37 connected to the inner end of the winding, the outer end of the winding being connected by the contact ring 30 of assembly 23 to the rail 13.
Velocity regulation of the wheel and axle assembly 17 is achieved by controlling the series connection between the respective wheel units 22 and 23, namely, by opening and closing said series connection. Thus, an electromagnetically-controlled switch assembly, designated generally at 38, is provided between the inner terminal conductor 39 of the wheel assembly 22 and the terminal wire 37 leading to the inner end of the Spiral coil of the wheel assembly 23.
The electromagnetically-controlled switch 38 comprises an annular control winding y40 rigidly-secured to a d6- pending supporting plate 41 which is, in turn, rigidlyconnected to the car frame. The supporting plate 41 is provided with an aperture 42 which is concentric with the axle 18, and the control coil 40 is mounted on the margin of the #aperture 42, being also concentric with axle 18, as will be apparent from FIG. 1. Rigidly-secured on axle 18 inside the coil 40 is a substantially annular block `43 of insulating material having an inner peripheral flange 44. Molded in the block 43 is a first conductor element 45 to the outer end of which the terminal wire 39 is connected. Conductor 45 has the peripheral outwardly-extending semicircular contact flange 46. Rigidlysecured on the block 43 opposite the conductor element 45 is another conductive metal element 47 having the general .semicircular outwardly-extending contact flange 48 which is symmetrically and diametrically-opposite the general semicircular outwardly-extending contact flange FIG. 2. Wire 37 is electrically-connected to the conductive member 47, as shown in FIG. l.
Designated at 49 is an annular conductive washer of copper, or other suitable non-magnetic material, which is rigidly-secured to the rim of a short cylindrical sleeve member 50 of magnetic material which surrounds the block 43 and which is biased away from flange 44 by a coiled spring 51 surrounding block 43 and bearing between flange 44 and the peripheral edge of the magnetic sleeve member 50. Spring 51 biases the annular Contact Washer 49 against an annular retaining collar element 52 of insulating material rigidly-secured on the inner end portion of insulating block 43. Thus, the coiled spring 51 biases the conductive ring 49 away from bridging contact with flange elements 46 and 48. When the coil 40 is energized, the magnetic sleeve 50 is attracted into the coil 40 and thus moves the conductive ring member 49 to the left, as viewed in FIG. 1, into bridging contact with the semicircular flange elements 46 and 48, thereby connecting wire 39 to wire 37. This establishes the series connection of the two cooperating wheel-motor assemblies 22 and 23, energizing same, and producing driving torque. When the coil 40 is de-energized, the spring 51 disengages the bridging ring 49 from the switch contact elements 46 and 48, opening the circuit and interrupting the series connection.
Any suitable control circuit for the coils 40 may be provided, such control circuits being conventional and in themselves, forming no part of the present invention. lt can thus be seen that any desired type of speed regulation may be achieved by correspondingly controlling the series connection of the driving wheel-motor assemblies.
In an analogous manner, wheel-motor assemblies may be provided which are suitably-wound to produce driving force in an opposite direction to the main driving force, for the purpose of providing braking action, or for providing reverse motion of the vehicle.
The housing members 33 may be secured to the side portions 11 of the vehicle frame in any suitable manner. Thus, the housing members 33 may comprise generally circular rings of magnetic material extending around substantially the entire peripheries of the disc members 24, 25 and being open merely at their bottoni portions adjacent the rails, as shown at 50 in FIG. 3. The housing members 33 are provided with spaced securing lugs 51 which are apertured to receive suitable fasteners, such as fastening screws 52, for securing the housing members to the depending side frame members 11 in the manner illustrated in FIGS. 1 and 3.
By so arranging the housing members 33 so that they extend adjacent the major portions of the peripheries of the associated magnetic wheel disc members 24 and 25, the efiiciency of the homo-polar wheel-motor assemblies is considerably increased since this provides maximum radial flux ow through the spiral homo-polar motor windings.
While a specific embodiment of an improved electric railway system of the type obtaining driving current from its associated rails has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.
What is claimed is:
1. In an electric railway system of the type having a pair of rails connected to a source of direct current, a vehicle having a frame, said vehicle being provided with a plurality of wheel yand axle assemblies connected to said frame and supported on said rails, at least one of said wheel and axle assemblies comprising an axle journaled to said frame and respective wheel assemblies mounted on said axle and engaging said rails, each wheel assembly comprising a pair of spaced circular discs of magnetic material mounted coaxially with the axle, a spiral homo-polar motor winding mounted between and parallel to the discs, and contact ring means between the peripheral portions of the discs substantially flush therewith and connected to the outer end of the winding, a respective housing member of magnetic material secured to the frame and extending adjacent the periphery of each wheel assembly, substantially defining a magnetic yoke relative to the magnetic discs of the wheel assembly, electrically-operated control switch means mounted substantially coaxially with said axle, and circuit means interconnecting the inner ends of the spiral homo-polar windings through said control switch means.
2. The railway system of claim 1, and wherein said control switch means has one portion xed to the frame and a cooperating portion fixed to the axle.
3. The railway system' of claim 2, and wherein said one portion of the control switch means comprises a coil secured to the frame and surrounding said cooperating portion.
4. The railway system of claim 3i, and wherein said cooperating portion comprises a pair of spaced contacts secured to said axle and conductive means controlled by said coil and being bridgingly engageable with said spaced contacts.
5. The railway system of claim 4, .and wherein said spaced contacts comprise a pair of diametrically-opposite concentric arcuate conductive metal segments coaxially mounted on and insulated from said axle.
16. The railway system of claim 5, and wherein said conductive means comprises a metal ring member surrounding said axle adjacent said arcuate segments, spring means biasing said ring member away from said segments, and magnetic means secured to said ring member and located in the field of said coil, said magnetic means being movable sutliciently responsive to energization of the coil to cause the metal ring member to conductively bridge said arcuate segments.
7. The railway system of claim 6, and wherein said magnetic means comprises an annular element of magnetic material coaxially secured to said metal ring member and being receivable inside said coil.
8. The railway system of claim 7, and wherein said axle is provided with a substantially annular block of insulating material having an annular flange, said arcuate metal segments being concentrically mounted on said block, said spring means comprising a coiled spring surrounding said block and bearing between said annular ange and said last-named annular element of magnetic material.
9. The railway system of claim 8, and wherein said discs of magnetic material have enlarged peripheral portions to decrease their reluctance at their peripheries adjacent their associated magnetic housing members.
10. The railway system of claim 9, and wherein the magnetic housing members have peripheral walls surrounding and extending closely adjacent the peripheries of the major portions of the magnetic discs.
11. In an electric railway system of the type having a pair of rails connected to a source of direct current, a vehicle having a frame, said vehicle being provided with a plurality of wheel and axle assemblies connected to said frame and supported on said rails, at least one of said wheel and axle assemblies comprising an axle journaled to said frame and respective wheel assemblies mounted on said axle and engaging said rails, at least one of said wheel assemblies comprising 'a pair of spaced disc-like members of magnetic material mounted substantially co-axially with the axle, a homo-polar motor winding mounted between and coaxial with said disc-like members, rail-engaging contact means connected to the outer end of the winding, means substantially defining a magnetic yoke relative to the magnetic disc-like members, and circuit means con necting the inner end of said motor winding to the rail engaged by the other wheel assembly mounted on said axle.
12. An electrical propulsion assembly comprising a pair of spaced coaxial disc-like members of magnetic material, a homo-polar motor winding mounted between and coaxially with said disc-like member, rail-engaging conductive contact means electrically connected to one end of said winding, means substantially dening a magnetic yoke relative to said magnetic disc-like members, further railengagng contact means axially spaced from said rst concontact means, and circuit means electrically connecting said further contact means to the other end of said windmg.
References Cited UNITED STATES PATENTS 433,181 7/1890 Parcelle 105--53 458,859 9/1891 Ries 104-148 806,217 12/1905 Wait 310-178 881,387 3/1908 Eastwood 310-178 X 3,479,967 ll/ 1969 Crompton 10S-53 FOREIGN PATENTS 347,856 9/ 1960 Switzerland 104-148 LM 943,189 12/ 1963 Great Britain 104--148 LM OTHER REFERENCES Steinmetz, C. P.: Theory and Calculations of Electrical Apparatus, New York, N Y., McGraw-Hill, 1st edition 1917, Chapter XXII, pp. 450458 inclusive, Tk 2181.S7.
ARTHUR L. vLA POINT, Primary Examiner H. BELTRAN, Assistant Examiner U.s. rc1. x.R. 10s-s3, 76; 31e-67, 17s