|Publication number||US3845720 A|
|Publication date||Nov 5, 1974|
|Filing date||Jan 17, 1973|
|Priority date||Jan 20, 1972|
|Also published as||CA970847A, CA970847A1, DE2220735A1|
|Publication number||US 3845720 A, US 3845720A, US-A-3845720, US3845720 A, US3845720A|
|Inventors||G Bohn, H Wende, G Winkle|
|Original Assignee||Krauss Maffei Ag|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (2), Referenced by (59), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Unite States Patent 1 1 aim et a1.
[ 1 Nov. 5, 1974 MAGNETIC-LEVITATION VEHICLE WITH AUXILIARY MAGNETIC SUPPORT AT TRACK-BRANCH LOCATIONS  Inventors: Gerhard Bohn; Gunther Winkle;
l-lelmut Wende, all of Munich, Germany  Assignee: Krauss-Matfei Aktiengesellschaft,
Munich, Germany 22] Filed: .lan.17,1973
 Foreign Application Priority Data Jan. 20, 1972 Germany 2202655 Apr. 27, 1972 Germany 2220735 52 us. Cl. 104/148 MS, 104/130  Int. Cl B601 13/00  Field of Search 104/148 MS, 130
 References Cited UNITED STATES PATENTS 3,750,803 8/1973 Paxton 104/148 MS FOREIGN PATENTS OR APPLICATIONS 707,032 5/1941 Germany 104/148 MS Primary Examiner-Robert S. Ward, Jr. Assistant Examiner-George l-l. Libman Attorney, Agent, or FirmKarl F. Ross; Herbert Dubno 5 7 ABSTRACT A magnetic-levitation or magnetic-suspension vehicle in which a pair of electromagnetic-suspension arrangements are spaced apart on the vehicle body and describe traces or paths which intersect at branching locations of the track, is formed with auxiliary magnet means, e.g. an electrodynamic system, permanent magnets or electromagnets, for temporarily supplying a supporting force when the vehicle travels to one side or another of a track branch along that limb of the vehicle path at which the normal suspension arrangement is rendered ineffective.
27 Claims, 19 Drawing Figures PAIENTEUNUV 5 m4 SHEET '02 [1F 10 PATENTEDHUY 5m: 3.845720.
SHEET 03UF10 PATENTEDNUV 5 I974 SHEET mar 10 PATENTEDNUV 5m 3.845720 SHEET uaur 10 I PATENTEDNBV 519M v 3.845720 SHEET 10,0F10
MAGNETIC-LEVITATION VEHICLE WITH AUXILIARY MAGNETIC SUPPORT AT TRACK-BRANCH LOCATIONS CROSS-REFERENCE TO RELATED APPLICATIONS The present application is related to the commonly assigned copending applications:
Ser. No. 268,132 filed June 30, 1972 now US. Pat. No. 3,804,022 and entitled ELECTROMAGNETIC SUSPENSION AND GUIDE SYSTEM FOR MAG- NETICALLY SUSPENDED VEHICLES;
Ser. No. 268,133 filed June 30, 1972 now US. Pat. No. 3,797,403 and entitled ELECTROMAGNETIC SUSPENSION AND DRIVE MEANS;
Ser. No. 280,073 filed Aug. 11, 1972 now US. Pat. No. 3,780,668 and entitled ELECTROMAGNETIC SUSPENSION AND/OR GUIDE SYSTEM ESPE- CIALLY FOR MAGNETICALLY SUSPENDED VE- HICLES;
Ser. No. 280,074 filed Aug. 11, 1972 and entitled ELECTROMAGNETIC SUSPENSION AND GUIDE SYSTEM, PARTICULARLY FOR VEHICLES; and
Ser. No.292,638 filed Sept. 27, 1972 now US. Pat. No. 3,804,499 and entitled CONTACT SYSTEM FOR HIGH-SPEED ELECTRICALLY OPERATED VEI-Il- CLES.
FIELD OF THE INVENTION The present invention relates to magnetic-levitation vehicles and track systems therefor in which the system comprises at least one branch wherein one track path diverges from another or converges toward the-other and in which normal magnetic suspension fails at the crossing region.
BACKGROUND OF THE INVENTION In recent years magnetic-levitation or magneticsuspension vehicles have become of increasing interest since they permit asubstantially contactless movement of a vehicle for the transport of goods or passengers along a track at relatively high speeds.
Conventional wheel-vehicle systems have the disadvantage that the vehicle speed is limited because of the frictional interplay between vehicle and the track system and within the wheel assemblies of the vehicle and, consequently, such wheel systems have been found to be unsatisfactory for many purposes.
Consequently, investigations into transport systems free from these disadvantages have cast attention upon so-called contactless systems in which the major part of the vehicle load is transmitted to the supporting track indirectly, e.g. via magnetic forces. A typical magnetic-levitation vehicle may comprise a vehicle body having two rows of suspension electromagnets, generally spaced apart by a distance approximating the width of the passenger compartment of the vehicle, to gain stability; the suspension electromagnets cooperate with ferromagnetic armature rails extending in similarly spaced relationship along the rack. Magnetic attractive forces are developed between the cores of the suspension electromagnets and the fixed armature rails to balance the gravitational force of the load and vehicle across air gaps which separate the armature rails from the cores of the suspension electromagnets. Gapspacing directors, responsive to the air gaps spanned by the magnet field, may be provided to maintain a constant gap width with varying load. so that the magnet field always is sufficient to meet the vehicle load but is not of sufficient strength to bring the vehicle into contact with the track.
In early magnetic-levitation vehicles, the suspension of the vehicle body was effected from a roof or overhead portion of the track and, consequently, branching of the track to selectively direct the vehicle along one or another of a pair of divergent; pathways (or conversely to transfer the vehicle from one pathway to another of a pair of convergent pathways) did not create any significant difficulties. However, such overhead systems (when used for the principal suspension) have other disadvantages, including that. of low stability, and
recent efforts in the field of magnetic levitation vehicles have concentrated upon suspension systems in which the suspension electromagnets lie at, or substantially at, the level of the center of gravity of the vehicles. In general, the center of gravity of the vehicle can be considered to lie in a horizontal plane between a pair of horizontal planes defining the top and bottom of the vehicle body and the suspension electromagnets are provided in the plane of the center of gravity of substantially in this plane.
With vehicle systems of this type, especially where the electromagnets of the two suspension arrangements on either side of the vehicle are formed on outriggers or the like, each magnet-suspension arrangement defines a trace or path along which the armature rail normally runs. Where, however, the vehicle track branches, a spur of the track diverges from another portion of the latter and the trace of the electromagnetic suspension arrangement on the outside of the divergent curve or spur cannot be supported by the usual armature rail since the latter must be interrupted if the vehicle is to be allowed to continue, in an alternative situation, along the nondivergent path. The problem, therefore, is to provide support for the vehicle even in these regions of track branching in which one of the normally used suspension-electromagnet arrangements becomes ineffective.
OBJECTS OF THE INVENTION It is the principal object of the present invention to provide a magnetic-levitation vehicle of the class described with improved means for supporting the vehicle during branching.
Another object of the invention is to provide a magnetic-suspension vehicle system wherein the aforementioned disadvantages are obviated and a satisfactory passage of the vehicle through a branching region of the track is ensured.
SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter are attained, in accordance with the present According to a more specific feature of the invention, the vehicle comprises a vehicle body having two suspension-electromagnet arrangements adapted to cooperate with respective armature rails and defining crossing traces or pathways in regions in which the track is branched, with one of the electromagnet arrangements being rendered ineffective depending upon the direction in which the vehicle travels as the latter negotiates the branch region. The invention provides that, in the region in which the electromagneticsuspension arrangement is ineffective (i.e. at the outer limb of a curve track diverging from another track or the limb of this track crossed by the diverging track) and incapable of exerting a tractive force upon its armature rail, the branch region and the vehicle are provided with a magnetic-cushion system which takes up the lost suspension force until the vehicle again reaches a position in which both of its electromagnet suspensions are effective. The term magnetic cushion" or magnetic support, and terms of similar import, are used herein to describe the substitution of a magnetic force (which may be either repulsive or attractive) in the branch regions in which the attractive force of the normal suspension arrangement fails.
Magnetic cushions of the repulsion type are able to take up the weight of the vehicle and are basically stable, requiring little or no control circuitry and thus are of low cost. The components carried by the vehicle need be only of relatively light weight so that the loadcarrying capacity of the vehicle is not seriously diminished by the presence of a magnetic-cushion system. The stability of the magnetic cushion derives from the repulsion force increases as the repelling magnet poles increasingly approach one another so that, regardless of the vehicle load, the gap is always maintained between the stationary member of the means for forming the magnetic cushion and the member carried by the vehicle.
According to an important feature of the invention, the magnetic-support means on the vehicle and track is provided completely independently of the magneticsuspension means, along a generally central location of the vehicle, or along two laterally separated portions of the vehicle, e.g. in two rows of support magnets. in either case, the support magnets carried by the vehicle and the support magnets mounted along the track have magnetic axes perpendicular to the planes of the pole faces, are of opposite magnetic polarity and have an orientation of the pole surfaces which is generally parallel to the direction of vehicle movement. The vehicle is formed with the permanent magnet or electromagnet members which have downwardly turned pole faces while the track is formed with upwardly turned pole faces of similar magnetic polarity. Such a system has been found to be effective independently of the vehicle speed.
While either the central arrangement or the arrangement wherein the magnetic members are laterally spaced apart may be used as described above, the latter system has been found to be most advantageous when stability about the horizontal axis (antiroll stability) of the vehicle is a problem. The rows of support magnets can be provided along the outer edges of the vehicle body, preferably at as great a distance from one another as is possible (since stability increases with increasing spacing).
The central magnet arrangement has the advantage that only one row of support magnets is required and hence the reduction in load-carrying capacity and the increase in the size of the structure for mounting the support-magnet arrangement is reduced; the magnets advantageously are transversely shiftable to allow the supporting forces to be applied to either side of a vertical median plane through the vehicle body in accordance with the suspension electromagnet arrangement which was rendered ineffective.
According to another feature of the invention, the support magnets of the vehicle may be offset laterally from the support magnets of the track with which they cooperate to take up the load previously carried by an ineffective electromagnetic suspension, the offset being calculated and arranged so as to provide a transverse or lateral guiding force which may replace the loss of lateral guidance when the electromagnetic suspension and/or guide arrangement on one side of the vehicle is rendered ineffective. It will be apparent that the offset between the similarly poled magnets of the vehicle body and the track creates a repulsion-force component in the lateral direction which is combined with the vertical or supporting component. The degree of lateral offset and the direction of such offset, of course, are determined by the direction and size of the lateralguide components which may be necessary (e.g. to balance a still-effective lateral force component of the operative electromagnetic suspension and guide means, to balance or counteract centrifugal force components and to counteract wind-force components).
According to another feature of the invention, the support magnets on the vehicle are provided in transversely spaced longitudinal rows for selective cooperation with respective support magnets of the track. It has been found to be advantageous, with this conformation, to provide a lateral-force component at the support magnets by canting the support magnets of the vehicle mirror-symmetrically with respect to a vertical median plane of the vehicle extending in the direction of displacement thereof. The supporting magnets of the track are preferably similarly canted. Thus the repulsion force between the support magnets of each pair (vehicle and track magnets) may provide not only an upward or supportive force component, but also a lateral guidance component as well.
According to an aspect of the invention, the support magnets of the vehicle are provided in a single row generally centrally of the vehicle, thereby effecting a saving in weight over the two-row system previously described. When this embodiment is provided, the vehicle maybe formed with means for laterally shifting the row of the supporting magnets in two opposite directions, i.e. to either side of the vertical median plane of the vehicle, while the rows of supporting magnets of the track, or a single row of the supporting magnets, may register with the vehicle magnets or may be offset somewhat therefrom to deliver the lateral force components as mentioned earlier. In a central magnet ar rangement for each trace of the vehicle, the vehicle magnets may be shifted to one side to provide the upward or supportive force component and a lateral force component to this side, while a movement of the row of vehicle support magnets to the opposite side of the single row'of track support magnets will contribute the upward force component in addition to a lateral force component to this other side. The transverse or lateral shiftability of the row of the supporting magnets may be used to direct the vehicle along the desired trace and enables the single row of supporting magnets to function similarly to the two rows of supporting magnets of the system discussed above. The stability and canting characteristics of the vehicle as it negotiates a curve may. be equal to the corresponding characteristics of a two-row system or improved thereover.
According to another feature of the invention, the vehicle is driven (receives thrust in the direction of travel) by linear electric motors of the reaction type. The term linear motor or linear induction motor" is used herein to describe a system iri which a field coil is carried by one member of two relatively linearly displaceable members and interacts magnetically with a reaction rail mounted upon the other member and in which an electric current is caused to flow to produce a travelling magnetic field which applies a thrust component in the direction of movement of the movable vehicle. The linear induction motor which may be employed in accordance with the present invention may be of the two-sided type in which a centrally disposed reaction rail is flanked by a two-sided field coil arrangement. ln a one-sided linear induction motor, the field coil confronts a face of the reaction rail.
When linear induction motors are provided to propel the vehicle according to the present invention, the reaction rails are mounted upon the track, preferably on opposite sides of the vehicle and cooperate with the field coil arrangements carried by the vehicle body, preferably on each side thereof. To enable the vehicle to be diverted, at a branch location, along one or another track, the linear induction motor at the side of the vehicle whose electromagnetic suspension arrangement is rendered ineffective for crossing of the traces, is similarly rendered ineffective and withdrawn from the associated reaction rail. in the case of one-sided linear induction motors, this may be achieved by providing the reaction rail in a vertical conformation such that the field coil is juxtaposed with a vertical flange of this reaction rail. ln the case of double-sided linear motors, however, the reaction rail preferably is horizontal with the field-coil arrangement straddling the reaction rail and confronting the latter from above and below the latter.
In the region of a branch, the linear induction motor normally providing the thrust for propelling the vehicle separates from the reaction rail at the outside of the curve, i.e. at the side of the curve at which a trace of the vehicle path crosses the vehicle path extending along the track or running along the other branch thereof. As a result, there is a temporary failure of the propelling thrust at this side and, according to another feature of the invention, a thrust contribution is supplied to compensate for the new loss of normal propelling thrust. This is accomplished by forming the support magnets as a linear induction motor and rendering the support motor effective at the side of the vehicle, in the branch region, at which the propelling motor thrust is reduced or fails.
windings which are parallel to the pole surfaces of the supporting magnets and extend in a direction transverse to the direction of travel, so that the magnetic fields of these windings cooperate with the row of supporting magnets on the underside of the vehicle at the outer portion of the curve to impart a thrust in the direction of the vehicle travel. The row of supporting magnets on the vehicle thus acts as a secondary of the direct-current linear motor.
It has already been mentioned that the supporting magnetsmay be permanent magnets or partly permanent magnets and partly electromagnets, a permanentmagnet arrangement having the advantage that no additional enerby is required for temporary support of the vehicle. In this embodiment of the invention, two rows of permanent magnets are provided along the underside of the vehicle with only the permanent magnet at the outside of a curve of a track branch being effective for temporary support. In order to avoid interference with the operation of the vehicle by the ineffective row of the support magnets, it has been found to be advantageous to recess the support magnets of the track below a point at which there is appreciable interaction between the track magnets and the vehicle magnets. The selective operation of the supporting magnets can be accomplished by the provision of means fore selectively raising and lowering the track magnets in accordance with the direction in which the vehicle is di verted. This is the case with two rows of permanent magnets which run from the entry into the branch region and through the branch region, but need not be the case where a single row of permanent magnets is employed since the two permanent magnet rows of the track may be united in the region of the entry and may diverge only at the heart of the branch region. The permanent magnets of the track can, moreover, slope upwardly toward the underside of the vehicle so as to gradually assume a supporting function, thereby preventing magnetic shock from developing in a vehicle traveling at high speeds. It has also been found to be possible to render one or both of the supporting magnets or rows of magnets of the vehicle ineffective by providing magnetic shields on the vehicle which may be shiftable to extend into the space between the supporting magnets or vehicle and track. Then only the shield for the supporting magnets on the outside of the curve need be shifted or withdrawn to render this pair of the supporting magnets effective.
Advantageously the magnetic shields are composed of soft-magnetic (soft-iron) plates on the pole faces of the permanent magnets on the underside of the magnetic-levitation vehicle, the shiels being shiftable to expose the pole faces. The widths of the plates (shields) must correspond to at least that of the pole faces and, unless measures are taken as described below, the stroke of each plate must be equal to or greater than the dimension of the pole face in the direction in which the plates are shiftable.
According to another feature of the invention, however, the stroke of the shiftable magnetic shields can be reduced by providing the permanent magnets on the underside of the vehicle in the form of a number of relatively narrow permanent-magnet bands or strips extending in the longitudinal direction and transversely spaced apart by gaps substantially equal in width to the widths of the magnets. The shield can then be formed as a grate of soft magnetic material (soft iron) whose bars have a width and a length equal to those of the permanent-magnet strips (i.e. are coextensive with the strips) and are adapted to be aligned or to register with the magnet strips in one position of the grate, thereby magnetically blocking interaction between the vehicle and track support magnets. The grate may then be shifted only through a distance equal to the width of the magnetic strip into alignment with the gaps to render the permanent magnets effective.
lt has also been found to be advantageous in some cases to substitute electromagnets for the support magnets on the vehicle and/or on the rack, the electromagnets being of the coreless type or having iron cores.
The use of electromagnets has the advantage that an appropriate pair of support magnets (along the outer limb of a curve in the branching region) can be rendered effective simply by switching (exciting) the relevant electrom'agnet coils. Since the inactive magnetic members need not be energized except when actually in use to provide auxiliary support for the vehicle, the pole faces remain free from magnetically attracted particles which, in vehicle systems having continuously active magnetic surfaces, have a tendency to accumulate as contaminants on the pole faces.
According to still another feature of the present invention, the auxiliary magnetic support is provided by an electrodynamic arrangement of the eddy-current type. In this case a centralmember or two laterally spaced electrodynamic members, e.g. coils energized by alternating or direct currents, can be provided on the underside of the vehicle for cooperation with reaction rails of high electrical conductivity but little, if any, ferromagnetic character. In this case, the magnetic field generated by currents induced in the reaction rails interacts with the field of the coils to produce a supportive force component.
Th advantage of an electrodynamic system resides principally in the simplicity of the rail member provided on the track, this member consisting merely of a rail of high electrical conductivity (e.g. of copper or aluminum) instead of a row of supporting magnets.
When direct-current energization of the coils is used, however, the vehicle speed along the branch trace must be relatively high although the enerby which must be supplied to create the supporting force is relatively small. A disadvantage which must be taken into consideration is the braking action of the electrodynamic system which can be compensated by the provision of additional linear induction motors using the conductive rail as a stationary rotor or reaction rail. In most cases, however, it will be found to be advantageous to emply alternating current excitation of the electrodynamic support coils, although this may involve greater power and capital cost, since the resulting support force is practically independent of vehicle speed and the excitation results in the formation of a traveling magnetic field at a reaaction rail which contributes a thrust component in the direction of vehicle travel.
It is important for the proper functioning of the various magnetic devices of the magnetic-levitation vehicle, that the support magnet systems have a minimum stray magnetic flux which might adversely effect magnetic sensors, the guide system and even the suspension system. An electrodynamic support system with low stray magnetic flux may have, according to a more specific feature of the invention, a field coil with windings upon the shanks or arms or web of a permanently magnetic U-profile core straddling a reaction rail positioned (e.g. in a vertical plane) parallel to the direction of travel and received between the arms of the U.
Coreless electrodynamic support systems can also be provided with advantage, according to the invention, when the coils have axes perpendicular to the track plane and the rail is generally horizontal or parallel to the track plane. The coils can be superconductive, with a small number of turns (e.g. a single turn) and a high magnetic cross section, thereby providing high eff|- ciency, without loss in high ampere-turn efficiency.
To render the electrodynamic support system effective when the temporary support is required at the outer limb of a curve of the vehicle at a branch track, and inneffective when the normal magnetic suspension is in use, the invention provides means for selectively raising the reaction rail into an effective position or interaction with the coils. When the electrodynamic support is not desired, the reactionrail at the appropriate side of the vehicle can be lowered. The means for raising and lowering the rails may include fluid-responsive devices, e.g. hydraulic or pneumatic cylinders.
At trace crossovers of the branch track region, a reaction rail can be provided for swinging movement into alignment with fixedly positioned (but vertically shiftable) reaction rails extending along the respective traces. The swingable rail section may be mounted for angular displacement about another vertical axis perpendicular to the track plane (i.e. a vertical axis) by any conventional rail-displacement means commonly used for mechanical switch tracks (e.g. a fluidresponsive device of the type described for raising and lowering the reaction rails).
Of course, the means for selectively raising and lowering the reaction rails need not be provided when and where the electrodynamic support system is rendered selectively effective and ineffective by exciting or switching off the coils carried by the vehicle.
It has previously been mentioned that magnetic shock can be avoided in the system by gradually bringing into play the magnetic repulsion forces, eg by having the magnets of the track or the reaction rail rise gradually to their effective positions with respect to the magnets or coils of the vehicle. In addition, it has been found to be advantageous to have the portion of the electromagnetic suspension which is to become ineffective and the auxiliary system which is to provide the supporting force in overlapping relationship in the longitudinal direction and in the direction of vehicle travel.
Whereas the systems described previously have concentrated upon arrangements for providing the supporting force by repulsion between permanent magnets or electromagnetic members, or between electrodynamic coils and a reaction rail, it is also contemplated in another aspect .of the invention to employ a magnetic attractive force for the supporting action in the region of a track branch.
In accordance with this aspect of the invention, an attractive supporting force is applied at the top of the vehicle, at least along the outer limb of the curve described by the latter at a branch. Accordingly, the vehicle may be'provided at the top thereof with two rows of transversely spaced controlled electromagnets, the band extending in the longitudinal direction for cooperation with respective armature rails along the underside of a roof or vault structure of the track, beneath which the vehicle passes. The additional cost of control circuits for these supportive electromagnets is meager since these circuits may use components also required to control the normal suspension electromagnets and- /or the devices described previously to direct the vehicle onto or to another branch. The transverse of the spacing of the rails (and support electromagnets) of the support system can differ from the spacing of the suspension system and preferably is greater than the latter spacing so that the intersections of the upper and lower traces do not coincide.
According to this aspect of the invention the magnetic strips on the vehicle side of the particular system have a particular spacing relative to each other so that DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
FIG. I is a diagrammatic cross-sectional view through a portion of a track crossover or branch of a magnetic-suspension vehicle system according to the invention, using a permanent-magnet cushion to support the vehicle in regions in which an electromagnetic suspension is rendered ineffective to permit crossover to a branch track;
FIG. 2 is a view similar to FIG. 1 showing the vehicle as it branches to the right;
FIG. 3 is a diagrammatic plan view of the branchtrack portion of the system, containing section lines along which the cross-sectional view of FIGS. 1, 2., 4, 7 and 8 are generally taken;
FIG. 4 is a diagrammatic cross-sectional view taken generally along the line IV IV of FIG. 3 of a vehicle system according to an embodiment of the invention which differs from the embodiment of FIGS. 1 and 2 (in which the permanent-magnet systems of vehicle and track register with one another upon branching), in that the permanent magnets do not register and thus provide a lateral force contribution;
FIGS. 5 and 6 are diagrammatic sectional views along vertical cross-sectional planes perpendicular to the direction of vehicle movement, illustrating magneticshield arrangements for selectively rendering the permanent-magnet systems effective and ineffective;
FIG. 7 is a diagrammatic cross-sectional view taken generally along the line VII VII ofa track system of the type illustrated in FIG. 3, but showing another magnet arrangement for temporarily supporting the vehicle on a branch of the track system in which one electromagnet suspension of the vehicle is ineffective, the position of the vehicle corresponding to that of FIG. 2;
- FIG. 8 is a diagrammatic cross-sectional view taken generally along a line corresponding to that shown at VIII VIII of FIG. 3, illustrating a system with canted supporting electromagnets, the vehicle being generally in a position corresponding to that of FIG. 2;
FIG. 9 is a diagrammatic cross-sectional view of a magnetic-levitation vehicle system using a banked track and a single row of temporary-support electromagnets on the vehicle for selective cooperation with the track magnets, the track and vehicle supporting magnets being offset to provide a lateral guide force in regions in which a normal lateral guide electromagnet system is temporarily ineffective over a portion of the outer curve of the branch;
FIG. 10 is a view similar to FIG. 9 of the system in which the vehicle curves to the right (assuming travel is away from the viewer) rather than to the left as is the case with the vehicle of FIG. 9;
FIG. II is a diagrammatic cross-sectional view taken in a vertical plane perpendicular to the direction of vehicle movement, of a system in which the supporting magnets of the vehicle lie in a single row centrally of the vehicle and wherein the supporting magnets can be shifted transversely to opposite sides of a vertical median plane of the vehicle;
FIG. 12 is a section similar to that of FIG. II with the vehicle in another position, both FIGS. 11 and 12 showing the vehicle is rightward movement (assuming traveling away from the viewer) as diagrammed in FIG.
FIG. 13 is a detail view, corresponding to a vertical section along a plane perpendicular to the direction of vehicle travel, diagrammatically illustrating an electrodynamic temporary support system according to a feature of the present invention;
FIG. 14 is a view similar to FIG. 13 illustrating another embodiment of an electrodynamic system for temporarily supporting a vehicle in the region of a track branch;
FIG. 15 is a diagrammatic plan view of a track embodying the electrodynamic arrangement of FIG. 13;
FIG. 16 is a diagrammatic vertical cross-sectional view through a tunnel-shaped tracl system according to another embodiment of the invention, the view being taken along a vertical plane perpendicular to the direction of vehicle movement along a line XVI XVI of FIG. 18 at the entry to the track branch;
FIG. 17 is a sectional view generally taken along the line XVII XVII of the track system of FIG. 8, i.e. at the core of the branch;
FIG. 18 is a plan view diagrammatically illustrating a track-branch layout for the system of FIGS. 16 and 17; and
FIG. 19 is a sectional view taken generally along a line corresponding to the line XIX XIX of FIG. 16,
showing a vehicle and track system corresponding to still another embodiment of the invention.
SPECIFIC DESCRIPTION GENERAL In the following description, reference will be made repeatedly to certain elements and concepts which, although functionally different, may appear to have similar designations and hence it is desirable to define these concepts and elements. The term electromagnetic suspension" is used herein to describe those elements of the system which provide normal magnetic attractive force (between rows of electromagnets of the vehicle and respective armature rails of the track) for holding the vehicle substantially out of contact with the track during normal vehicle travel, while the term magnetic support and terms of similar import are used to describe the application of magnetic repulsion or attractive force'temporarily in the branch region in which part of the electromagnetic suspension fails. The electromagnetic suspension generally includes two rows of suspension electromagnets of the vehicle body in a plane (substantially horizontal) of the center of the gravity of the vehicle and thus between the horizontal planes defining the top and bottom of the vehicle. The suspension electromagnets cooperate with respective armature rails on opposite sides of the track to provide magnetic levitation so that the vehicle may travel along the track in a contactless state regardless of vehicle loading.
A typical system may also include lateral-guide electromagnets on the vehicle, whose function may be taken up in whole or in part by the suspension electromagnets, which cooperate with the same or different armature rails and, during normal travel of the vehicle (before and after a branch), provide oppositely directed lateral forces tending to center the vehicle on the track and resisting the internal lateral force of centrifugal action on turns and curves and the external lateral force of the wind. The terms lateral and transverse" are used to indicate a direction (generally horizontal) which is perpendicular to the direction of vehicle movement while the term longitudinal is used to designate the direction of vehicle movement. The term support magnet and terms is of similar import are used to refer to the electrodynamic systems, electromagnets or permanent magnet systems described in detail hereinafter and serving to provide temporary support for the vehicle at track branches in those regions in which the electromagnetic suspension may be rendered ineffective by reason of the separation of a row of suspense electromagnets from itsarmature rail.
. Finally, insofar as the general terminology used herein is concerned, the term track is embodied to designate the support structure extending along the path of the vehicle and provided with branches, forks of crossovers, the term branch" is used to designate that portion of the track at which one vehicle pathway diverges from or converges toward another (regardless of which pathway is used), the term spur is used to indicate a portion of a branch curving away from a straight or oppositely curved track portion, the term outer limb is used to indicate the outer portion of a curve of a spur, the term trace is used to designate the paths described by each suspension-electromagnet row and (at least in the region of a branch) is the imaginary line along which an armature rail would extend for the suspension electromagnets if such rail could be complete through the branch, the term core is used herein to refer to the branch, designates the region in which. are. trace .qrpathaaysross s 9L1? t sep an: other pathway (i.e. the righthand trace of one pathway crosses over the lefthand trace of the other), and the term vehicle is intended to refer to a body adapted to carry passengers or freight, which is controlled by an operator within the vehicle for or by some remote automatic controller or operator, which apart from the magnet system is and the structure carrying same may have any desired configuration (i.e. those of the copending applications) and which is designed to travel along the track with a minimum of direct contact (apart of the use of brushes or shoes cooperating current-carrying rails or the like) with the track, the weight of the vehicle and any load carried thereby being predominantly transferred by magnetic force to the track.
PERMANENT-MAGNET CUSHION (FIGS. 1 4) In FIGS. 1 and 2, there is shown a magnetic-levitation vehicle 1 adapted to travel along a track system 2, a branch portion of which has been shown diagrammatically in plan view in FIG. 3. The system comprises a two-branch support track 3 for the vehicle 1, having a pair of support rails 4 mounted along the underside of a pair of inwardly extending horizontal flanges of the channel-shaped track structure 3 into which the lower portion of the vehicle 1 reaches.
The armature rails 4 are of U-profile with horizontal webs affixed to the horizontal flanges and vertically downwardly extending pole pieces or legs. Each of the ferromagnetic armature rails 4 is associated with a row 5, 5' of suspension electromagnets mounted upon the upper surfaces of a respective outwardly extending lateral flanges or Outriggers at the bottom of the vehicle or undercarriage. Preferably, each of these electromagnet arrangements is received between a pair of vertical planes defining the lateral outsides of the vehicle body.
Each suspension electromagnet 5 or 5 has an upwardly channel-shaped (U profile) core of ferromagnetic material whose web is wound with a coil and whose arms reach upwardly as pole pieces toward the pole pieces of the respective armature rail 4. The alternate electromagnet 5 and 5 along each row have their cores mutually laterally offset along the row (see the cited copending applications).
During normal (nonbranching operation), each row of electromagnet 5, 5 exerts an attractive force upon the respective rail 4 with excitation of the coils of the electromagnets, thereby generating an upward force component which balances the vehicle weight and load. As is known and has been described in the aforementioned applications, the control circuitry for the coils can include inductive or other sensor means between the suspension electromagnets and the respective rails to maintain the width (spacing) of the air gap spanned by the magnetic field substantially constant.
Furthermore, the offset arrangement of the electromagnet 5, 5' of each row provides a lateral-guidance role for the suspension electromagnets since the electromagnets 5 offset to the right (FIGS. 1 and 2) produce attractive force components to the left whereas the electromagnets 5' offset to the left produce a counterbalancing lateral force component to the right. When the electromagnets of each row offset to the right are provided with a control circuit independent of that controlling the electromagnet offset to the left, the lateral-force components can be adjusted during travel of the vehicle 1 to maintain the latter centered within the track against the disturbing forces such as the centrifugal force produced when the vehicle negotiates a curve and wind forces.
The vehicle 1 is driven by a pair of two-sided linear induction motors 6, each of which has a pair of field coils (stator windings) mounted on the underside 10 of the vehicle body and upon a flange projecting laterally therefrom so that the horizontally oriented coils define a laterally open gap between them. Of course, the coils may have a vertical orientation, if disposed on one side of a reaction rail mounted on edge, i.e. in a vertical plane, so as to enable lateral separation of the parts of the linear induction motor.
The horizontal reaction rail 7 (FIGS. 1, 2 and 4) assigned to each linear induction motor reaches into the respective gap from a corresponding wall of the track channel upon which the rail is mounted. Thus the rails 7 can be laterally withdrawn from between the windings of the respective stator 6, or the stator can be displaced (with the vehicle in a branching region of the track.
Conventional principles govern the operation of the two linear induction motors illustrated in FIGS. ll, 2 and 4, the motors of each vehicle being disposed mirror-symmetrically with respect to a vertical median plane of the vehicle 1 extending longitudinally and perpendicular to the plane of the paper in FIGS. 1 and 2. Where no other drive means is illustrated in the subsequently described Figures, it will be understood that a two-sided linear induction motor of the type presently under discussion may be employed. Each reaction rail 7 may be composed of a bar of magnetically active (ferromagnetic) material bearing a band of a highconductivity substance (e.g. copper of aluminum) which can carry an exciting current. The magnetic field generated by this current interacts with the magnetic field induced in the stator coils to produce a traveling magnetic field which provides a thrust in the direction of vehicle travel.
In addition, the underside II) of the vehicle 1 carries two rows 3 of permanent magnets, the rows extending in the longitudinal direction. The magnetic axes of these permanent magnets are perpendicular to the plane of the track and the magnets have pole faces of the same polarity oriented in the same direction i.e. turned downwardly. These permanent-magnet rows 8 provide magnetic support to the vehicle I in the region of a track branch along the outer limb of the curve path of the vehicle. Each track branch is provided at its core (i.e. the region between positions B D) with a pair of permanent-magnet rows 9 adapted to selectively provide the magnetic support function by a repulsion-type of interaction with the electromagnets of rows 8 at least in the region of the branch at which the corresponding electromagnetic suspension arrangement is rendered ineffective.
The permanent magnets of rows 9 are so positioned that they magnetically register with the corresponding rows 8, at least at the entry and exit sides of the branch, i.e. are disposed directly below the support magnets of the vehicle such that the magnetic lines of force between the vehicle and track-support magnets are vertical and no substantial transverse force component is produced (see FIG. ll).
The magnetic axes of the permanent magnets of rows 9 are also perpendicular to the track plane, although the magnets are oriented oppositely to the orientation of the vehicle support magnets whereby the same magnetic poles (north as illustrated in FIG. I) of the magnets of each pair of rows 8 and 9 confron one another.
As will be apparent from FIG. 3, the rows 9 of track magnets extend to the entry side (region A B) and to the exit side (region D F) of the branch beyond the core region (B D) thereof, so as to overlap stilleffective portions of the electromagnetic suspension arrangements which are to become ineffective in the core region (B D). This insures a shock-free transition from normal suspension to temporary support and vice versa.
Since, at the entry (region A B) of the branch both permanent-magnet rows 9 of the track magnetically register with the respective permanent magnet rows 8 on the underside 10 of the vehicle I while only one of the row pairs 8/9 is to be effective to provide magnetic support (at the outer limb of the curve depending upon the direction to which the vehicle is to be diverted), means is provided (e.g. fluid-responsive means as shown in FIGS. I3 and 14) for selectively raising and lowering the rows 9 of permanent magnets. In other words, in the region in which magnetic support is not desired, the corresponding row 9 of electromagnets is not desired, the corresponding row 9 of electromagnets is lowered out of interacting relationship with the corresponding row 8 of support magnets on the underside of the vehicle. Assume, therefore, that the vehicle traveling upwardly along the track of FIG. 3 is to branch to the right. In the region A B, the right-hand row of electromagnets 9 is raised (FIG. 1) to begin magnetic support as the electromagnetic suspension force along the outer limb of the right-hand curve is lost (starting at location B and continuing to location D). Where, of course, the ineffective row of track magnets is laterally offset sufficiently from the associated row of vehicle magnets (as is the case in the region C D), there need not be a lowering of the track magnets, although such lowering is advisable to avoid interaction of the unused row of track magnets with the other magnetic systems of the vehicle.
When the vehicle 1 enters a branch of the type shown in FIG. 3, the permanent magnet rows 8 and 9 along the side of the vehicle at which electromagnetic suspension isto be lost, i.e. at the outer limb of a curve, provide a temporary support for the vehicle, the electromagnets 5, 5' of the suspension arrangement along this outer limb being gradually de-energized so that a smooth transition is made between suspension and temporary support. The de-energization of the electromagnets 5 and 5' at the outer limb of the curve can be effected automatically, e.g. with the aid of sensors responsive to the diversion ofthe electromagnet arrangement from its armature rail. Similarly, as the vehicle leaves the branch, a gradual increase in the energization of the electromagnet arrangement whichis to be come effective is provided so that the transition from magnetic support to normal suspension is also smooth. Where possible, the track support magnets which are to become effective, rise from their lower positions (right-hand side of FIG- 1) to their upper positions (left-hand side of FIG. 1) over the entry region A B and the exit region E F to provide a gradual increase in the supporting force.
In FIG. 2, there is shown a position of the vehicle within the core region B D of the branch. In this position, the vehicle which has branched to the right (FIG. 3) has its left-hand support magnets in magnetic registry and the righthand support magnets sufficiently offset from one another so that recessing of the permanent magnets 9 is not required. As the vehicle leaves the branch region, the operation sequence previously described is reversed and, at D, the sensor of the outer limb armature rail 4 (approached by the previously inactive row of suspension electromagnets 5, 5') automatically energizes these electromagnets to develop electromagnetic suspension force as the hitherto effective row 9 of track magnets gradually recedes away from its associated permanent magnets 8. In the region E F, therefore, the support system becomes ineffective and beyond position F, the vehicle may be supported entirelyby the suspension electromagnet.
Each of the rows 9 of the track magnets (FIG. 2) is additionally provided with a primary winding 11 of a direct-current linear motor 12, for which the juxtaposed row of permanent magnets 8 on the underside 10 of the vehicle acts as a reaction rail or so-called linear rotor. The winding is energized by direct current and produces a magnetic field which interacts with the vehicle magnets 8 to provide a thrust in the longitudinal direction, thereby compensating for any loss of thrust at the portion of the vehicle traveling along the outer limb of the curve and resulting from a separation of the linear induction motor stator 6 from its reaction rail 7. The direction of this thrust is determined by the direction of current flow through the coil. The supplemental linear-motor thrust provided in the region in which one of the normal drive motors becomes ineffective, prevents overloading of the linear induction motor 6 along the inner limb of the curve.
FIG. 4 diagrammatically illustrates a vehicle, according to another embodiment of the invention, being diverted to the right at a branch of the type shown in FIG. 3. This vehicle system differs from that previously described in that a guide system 14 is provided separate from the electromagnetic suspension system 13. The
electromagnetic suspension system 13 is generally similar to the suspension described in connection with electromagnets 5, 5 and illustrated in FIGS. 1 and 2, except that all of the electromagnets of each row are aligned (rather than alternately offset) and have pole pieces which are vertically juxtaposed and directly opposite the downwardly extending pole pieces of the respective armature rails. Thus the electromagnetic sys pension provides only a vertical force for retaining the vehicle in a contactless state during travel along the track and is not able to provide any lateral or transverse guiding force for centering of the vehicle.
The separate electromagnetic guide system 14 functions onlyto provide lateral or centering forces and to provide the forces necessary for selectively diverting the vehicle, but makes no contribution to the electromagnetic suspension force. The guide system comprises two armature rails 15 of ferromagnetic material and a U-profile, the webs of these rails being fixed to inwardly extending flanges of the channel-shape track structure 3 so that the webs lie in vertical planes substantially coinciding with the vertical planes defining the flanks of the vehicle. The armature rails 15 have horizontally extending legs or pole pieces which are juxtaposed with U-shaped magnetic cores of electromagnets mounted on opposite sides of the vehicle and forming part of the guide system 14. The cores of these electromagnets have webs carrying respective coils and lying in vertical planes while the shanks or pole pieces of the cores extend in horizontal planes to confront the pole pieces of the respective armature rails.
Normally, the vehicle is suspended by the system 13 which is provided with circuitry as described in the aforementioned copending applications, for maintaining a constant suspension gap in spite of variations in loading of the vehicle and is laterally guided by the system 14 which provides balanced forces acting in opposite directions on the opposite sides of the vehicle to center the latter. When an external force, e.g. wind force, tends to shift the vehicle laterally in one direction, the guide arrangement 14 at the side to which the vehicle tends to move may have its magnetic force reduced while the magnetic force of the other guide arrangement is increased to maintain the lateral gaps constant and the vehicle centered.
When, however, the vehicle enters a branch region as shown in FIG. 3, not only is the suspension force at the outer limb of the curve lost, but the lateral guide'force maintaining the vehicle in a proper position along the track, is likewise lost because of the separation of the armature rail 15 from the outer limb electromagnets with which it cooperates. It is desirable, in this case, to provide a lateral force component compensating the loss of this lateral force contribution. This can be achieved, according to the present invention, by offsetting the permanent magnet row 9 of the track to one side of the permanent magnet row 8 of the vehicle with which it cooperates, namely to the inside as shown in FIG. 4. The repulsion action here takes place with an inclination to the left so that the repulsion forces can be resolved into a vertical component and a lateral component, as illustrated, the lateral component having the value P,,. If the lateral force component of the electromagnet guide system 14 along the inner limb of the curve which remains effective, is represented at P,, the force relationships in the curve can be represented as P;= P P where P is the centrifugal force component which acts outwardly. Since the centrifugal force component in part replaces the horizontal component normally contributed by the guide arrangement at the outer limb of the curve, the permanent magnets 8 and 9 need not be dimensioned massively to provide the slight additional horizontal force increment necessary to stabilize the system.
MAGNETIC-SHIELD SYSTEM (FIGS. 5 AND 6) The raising and lowering of the permanent magnet rows 9 of the track 3 at the entry region A C F IG. 3) can be avoided when each of the permanent magnet rows 8 on the underside 10 of the vehicle 1 is provided with a magnetic shield.
In FIG. 5, the permanent magnet rows 9 are fixed to the track 3 and, for shielding the magnetic fields of the permanent magnets 8, the underside 10 of the vehicle is provided with soft-magnetic (soft iron) plates 16, shown for the right-hand row of permanent magnets in FIG. 5, to overlie and cover the pole face 17. The lefthand row of magnets 8 is shown to be unobstructed by its magnetic shield 16.
Before the vehicle enters the branch region of the track, both of the shields may cover the respective rows 8 of permanent magnets on the vehicle. When a rightward deflection of the vehicle is desired (assuming the vehicle enters the branch of FIG. 3 from below), the left-hand shield 16 is withdrawn by a lateral displacement of the shield, e.g. using a pneumatic or hydraulic cylinder, so that the exposed row 8 of vehicle magnets can interact with the juxtaposed row 9 of track magnets, thereby providing magnetic support at the outer limb of the curve. When the vehicle is to travel alone, the other spur, the left-hand shield 16 is shifted to obstruct the pole face 17 of the left-hand row of permanent magnets 8 while the shield previously obstructing the right-hand row of permanent magnets 8 is shifted to the left. Here again the exposed magnetic members provide support for the vehicle along the outer limb of the curve.
The plate 16 need be only so thick that a strong magnetic flux is prevented from developing between the two magnetic members in the gap of which the shield is inserted. In other words the magnetic shield need not be of such material and thickness that it will completely block magnetic interaction between the two members, but only of a thickness and material sufficient to weaken the magnetic field of the permanent magnet rows 8 beyond the shield.
The lateral stroke of the shield can be reduced when, as shown in FIG. 6, each row 8 of the permanent magnets affixed to the underside of the vehicle, is formed from a plurality of transversely spaced longitudinally extending permanent-magnet bands or strips 18 adapted to register with permanent-magnet bands or strips 19 of the track support magnets 9. The magnets 18 are spaced'apart by a center-to-center distance a, are of a width a/Z, define gaps of a width a/2 between them, and are substantially coextensive in the lateral direction with the magnetic strips of the track. In this case, the shield comprises a soft-magnetic grate 20 whose bars 21 are coextensive in number, width, length and spacing with the magnetic strips 18. In this case, the magnetic strips can be exposed through the gaps between the bars in one position of the laterally shiftable grate but are obstructed by the bars in another position. The grate need only be shifted by half the spacing a of the magnets, i.e. by a distance a/2, corresponding to the width of the strip.
ELECTROMAGNETIC SUPPORT SYSTEM (FIGS. 8 12) The vertical mobility of sections of a row of magnets on the track to selectively bring the track-support magnets into play and out of operation can be eliminated when, instand of permanent magnets for the support function, electromagnets are employed. As the vehicle enters the branch region, with an electromagnet support arrangement, the vehicle and track support electromagnets along the outer limb of the curve can be energized while the support electromagnets along the inner limb of the curve remain de-energized. The energization of the effective support electromagnets can be gradual, e.g. increasing current amplitude with increasing movement of the vehicle into the branch or curve, so that the support force is proportional to the loss of the suspension force, the latter decreasing as the vehicle passes further into the branch region. The use of electromagnets with variable energization in this manner also renders superfluous systems in which the track magnets gradually rise toward maximum interaction with the vehicle support magnets.
In FIG. 7, there is shown an embodiment of the present invention in which electromagnets 24 and ZSare provided along the track and the vehicle in the branch region. The vehicle I is here provided with two onesided linear induction motors 23 on opposite sides of the vehicle, adapted to drive the vehicle along the track. The one-sided linear induction motors 23 may include field coils arranged vertically and juxtaposed laterally with the face of the reaction rail disposed on edge (in a vertical plane) and carried by inwardly projecting flanges of the track system. Since the field coils of the linear induction motors 23 are disposed inwardly of the reaction rails, the vehicle may be laterally drawn away from one or the other reaction rails within the track branch. Of course, the two-sided linear induction motor of FIGS. 1 and 2 may be used herein as well and the one-sided motor system (consisting of two motors) may be used for any of the other vehicle and track embodiments disclosed.
The vehicle 1 and the track 3 are provided with a two-trace electromagnetic suspension and guide system, the individual suspension and guide arrangements of which are generally represented at 2 and having the configuration illustrated in and described with reference to FIGS. 1, 2 and 5, the traces crossing in the branch region. Since thevehicle of FIG. 7 loses both its suspension force and its lateral guidance force along the outer limb of the curve as it is diverted onto a spur (eg the right-hand spur of FIG. 3), the electromagnets 24 and 25 are preferably offset from one another to provide alateral force component. Of course, where the electromagnetic suspension which remains operative is of the type which can develop double acting centering forces, the centrifugal force can be balanced against the sum of the lateral forces of the electromagnetic suspension and the electromagnetic support systems, the sum of the centrifugal force and a similarly acting support-force component can be balanced by the counteracting lateral force of this suspension and guide arrangement, etc. The electromagnetic support system may provide a lateral force contribution P, which is directed toward the branch to which the vehicle is to be diverted.
The electromagnets 24 and 25 have magnetic axes which are perpendicular to the plane of the track, are energized by direct current, and may have coils wound around central posts or cores along these axes.
In FIG. 8 there is shown another electromagnet support arrangement for achieving lateral centering forces. In this embodiment, the electromagnets 24 and 25 on the underside 10 of the vehicle and on the track 3 are canted inwardly and downwardly. The electromagnets 25 on the vehicle 1 of FIG. 8 are mirror-symmetrical with respect to a vertical median plane through the vehicle in the direction of travel thereof. The vehicle 1 carries the electromagnetic support and guide arrange ments 2 as previously described and a pair of linear induction motors 23 as described with reference to FIG. 7. In this embodiment, the centrifugal force P is directed to the left (toward the outer limb of the curve) and is balanced by the control force P, of the effective electromagnet and guide arrangement, and a force p in the direction of the effective suspension and guide electromagnet system. Because of the inclination of the two electromagnets 24 and 25, the repulsion force between them lies along their common axis and thus slopes inwardly to the vertical. This force can be resolved into a vertical component (support force) and the horizontal component P The ineffective rows of electromagnets 24' and 25' here are spaced apart sufficiently so that they do not interact.
FIGS. 9 and 10 are cross-sectional views illustrating a branch system in which a straight track (left-hand track) and a curved right-hand track, form part of the branch. In this system, the straight track is represented at 3" and is shown to be canted or banked. In FIG. 9, the position of the vehicle 1 is shown as it travels over the straight track whereas FIG. Ill shows the position of the vehicle as it banks to the right.
' In this embodiment, a single row of electromagnets 26 is provided substantially at the center of the underside I0 of the vehicle, i.e. in the vertical median plane,
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|U.S. Classification||104/130.2, 104/283|
|International Classification||B61B13/08, B60L13/00|
|Cooperative Classification||B60L2200/26, B61B13/08, B60L13/003|
|European Classification||B61B13/08, B60L13/00B|