U.S. patent number 3,845,720 [Application Number 05/324,350] was granted by the patent office on 1974-11-05 for magnetic-levitation vehicle with auxiliary magnetic support at track-branch locations.
This patent grant is currently assigned to Krauss-Maffei Aktiengesellschaft. Invention is credited to Gerhard Bohn, Helmut Wende, Gunther Winkle.
United States Patent |
3,845,720 |
Bohn , et al. |
November 5, 1974 |
MAGNETIC-LEVITATION VEHICLE WITH AUXILIARY MAGNETIC SUPPORT AT
TRACK-BRANCH LOCATIONS
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.
Inventors: |
Bohn; Gerhard (Munich,
DT), Winkle; Gunther (Munich, DT), Wende;
Helmut (Munich, DT) |
Assignee: |
Krauss-Maffei
Aktiengesellschaft (Munich, DT)
|
Family
ID: |
25762595 |
Appl.
No.: |
05/324,350 |
Filed: |
January 17, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Jan 20, 1972 [DT] |
|
|
2202655 |
Apr 27, 1972 [DT] |
|
|
2220735 |
|
Current U.S.
Class: |
104/130.02;
104/283 |
Current CPC
Class: |
B60L
13/003 (20130101); B61B 13/08 (20130101); B60L
2200/26 (20130101) |
Current International
Class: |
B60L
13/00 (20060101); B61B 13/08 (20060101); B60l
013/00 () |
Field of
Search: |
;104/148MS,130 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Ward, Jr.; Robert S.
Assistant Examiner: Libman; George H.
Attorney, Agent or Firm: Ross; Karl F. Dubno; Herbert
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. In a magnetic-suspenion vehicle system comprising a track having
at least one branch region at which one track portion diverges from
another track portion, and a vehicle magnetically suspended on said
track and selectively directable onto said track portion, the
improvement which comprises, in combination:
respective suspension electromagnets extending along opposite sides
of said vehicle and cooperating with respective armature rails
formed along said track, said rows of suspension electromagnets
describing intersecting traces at said branch region, said armature
rails being disposed at the sides of the vehicle so that a gap is
formed in at least one of the rails at the branch region to permit
the vehicle to selectively traverse said portions; and
cooperating means on said vehicle and said track, at least in said
region, and effective to provide a magnetic supporting force for a
side of said vehicle through said region at which the corresponding
row of suspension electromagnets is ineffective.
2. The combination defined in claim 1 wherein said cooperating
means includes at least one row of supporting magnets mounted on
said vehicle and at least one magnetic member mounted on said
track, said supporting magnets and said magnetic members developing
a force field between them.
3. The combination defined in claim 2 wherein said row of
supporting magnets is mounted generally centrally on said vehicle
and is shiftable laterally to opposite sides of a vertical median
plane through said vehicle.
4. The combination defined in claim 2 wherein said magnetic member
is a row of supporting magnets having poles confronting those of
said supporting magnets and of identical magnetic polarity, the
magnetic axis of said support magnets being generally perpendicular
to said track.
5. The combination defined in claim 2 wherein said support magnets
are electromagnets.
6. The combination defined in claim 5 wherein said support
electromagnetic have magnetic axes perpendicular to said track and
said magnetic member is a row of oppositely oriented electromagnets
having magnetic axes generally perpendicular to said track.
7. The combination defined in claim 5 wherein said support magnets
are provided in a row along an edge of the top of said vehicle and
said magnetic member is mounted upon said track above said
vehicle.
8. The combination defined in claim 7 wherein said magnetic member
is an armature rail.
9. The combination defined in claim 8 wherein a second row of
support electromagnets is formed on the top of said vehicle at a
spacing from the first-mentioned row of support electromagnets
which is greater than the spacing of said rows of suspension
electromagnets from one another.
10. The combination defined in claim 2 wherein said cooperating
means includes two rows of transversely spaced supporting magnets
mounted on the underside of said vehicle, and respective magnetic
members extending along said track for cooperation with said rows
of supporting magnets.
11. The combination defined in claim 10 wherein said supporting
magnets are permanent magnets.
12. The combination defined in claim 10 further comprising means
for selectively raising and lowering said members relative to said
rows of supporting magnets to render a respective magnetic member
and the associated row of supporting magnets effective in
magnetically supporting said vehicle.
13. The combination in claim 10 wherein said rows of supporting
magnets are canted to generate a lateral force component upon
interaction of one of said magnetic members with the respective row
of supporting magnets.
14. The combination defined in claim 10 wherein each magnetic
member and the respective row of supporting magnets magnetically
register to develop a force field therebetween free from any
substantial lateral force component.
15. The combination defined in claim 10 wherein each magnetic
member and the respective row of supporting magnets are laterally
offset upon the development of a force field therebetween to
generate a lateral force component.
16. The combination defined in claim 10, further comprising a
magnetic shield selectively interposable between each of said rows
of supporting magnets and the respective magnetic member.
17. The combination defined in claim 16 wherein each of said rows
of supporting magnets comprises a plurality of permanent-magnet
strips extending longitudinally along said vehicle and said shields
are grates of soft magnetic material coextensive with said strips
and shiftable transversely relative to said strips to render said
supporting magnets selectively effective and ineffective.
18. The combination defined in claim 10 wherein said supporting
magnets are permanent magnets having pole faces of one magnetic
polarity turned toward the respective magnetic member, and each
magnetic member is a row of permanent magnets having pole faces of
the same magnetic plurality juxtaposed with those of said
supporting magnets, thereby generating a repulsion force between
said supporting magnets and the respective row of permanent magnets
of the associated member.
19. The combination defined in claim 10 further comprising
linear-induction motor means on said vehicle and said track for
imparting thrust to said vehicle in a direction of displacement
thereof along said track.
20. The combination defined in claim 19 wherein said
linear-induction motor means includes a respective motor at each
side of said vehicle, one of said motors being ineffective in said
region, the corresponding row of supporting magnets and magnetic
members being formed with means for imparting a thrust to said
vehicle to compensate for the loss of thrust upon inactivation of
said one of said motors.
21. The combination defined in claim 10 wherein said supporting
magnets are electromagnets and said magnetic members are
electromagnets.
22. The combination defined in claim 10 wherein said suspension
electromagnets lie generally in a plane of the center of gravity of
said vehicle, said track being generally channel-shaped and said
vehicle being received within the channel-shaped track.
23. The combination defined in claim 1 wherein said cooperating
means includes an electrodynamic coil assembly on said vehicle and
a reaction rail of high conductivity on said track cooperating with
said electrodynamic coil assembly to provide a supporting
force.
24. The combination defined in claim 23, further comprising means
for selectively raising and lowering the reaction rail relative to
said coil assembly.
25. The combination defined in claim 24 wherein said coil assembly
is superconductive and has an axis perpendicular to the axis of
said track, said reaction rail extending generally parallel to the
track.
26. The combination defined in claim 24 wherein said coil assembly
includes a magnetic yoke having arms straddling said reaction rail
and carrying a coil.
27. The combination defined in claim 23 wherein said reaction rail
has a section swingable about an axis perpendicular to said track
for directing said vehicle selectively onto said portions.
Description
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 U.S. Pat. No. 3,804,022
and entitled ELECTROMAGNETIC SUSPENSION AND GUIDE SYSTEM FOR
MAGNETICALLY SUSPENDED VEHICLES;
Ser. No. 268,133 filed June 30, 1972 now U.S. Pat. No. 3,797,403
and entitled ELECTROMAGNETIC SUSPENSION AND DRIVE MEANS;
Ser. No. 280,073 filed Aug. 11, 1972 now U.S. Pat. No. 3,780,668
and entitled ELECTROMAGNETIC SUSPENSION AND/OR GUIDE SYSTEM
ESPECIALLY FOR MAGNETICALLY SUSPENDED VEHICLES;
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 U.S. Pat. No. 3,804,499
and entitled CONTACT SYSTEM FOR HIGH-SPEED ELECTRICALLY OPERATED
VEHICLES.
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 magnetic-suspension vehicles
have become of increasing interest since they permit a
substantially 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. Gap-spacing 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 invention, by providing at
least temporarily and in the region of a track branch at which the
armature rail of a normal electromagnetic suspensions must be
interrupted to allow the vehicle to negotiate the branch, a
magnetic support system adapted to take over at least part of the
magnetic load of the ineffective electromagnetic suspension without
direct contact with the vehicle. The normal electromagnetic
suspension may be of any of the types shown and described in the
aforementioned copending applications.
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
electromagnetic-suspension 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 load-carrying 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 magnetic-suspension 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 lateral-guide 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 may be 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 arrangement 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 in
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. In 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. In 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.
The linear induction motor formed by the support magnets may
include field windings carried by the primary magnets on the track
and reacting with the supporting magnets and cooperating with the
supporting magnets of the vehicle. The two rows of supporting
magnets carried by the track are thus provided with the primaries
of direct-current linear motors and with 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 magnets may be
permanent magnets or partly permanent magnets and partly
electromagnets, a permanent-magnet 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 diverted. 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 f 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.
It 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 electromagnet 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 central member
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
efficiency, 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 reaction rail 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 fluid-responsive 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, e.g. 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 no overlap of two inner branch
tracks need occur. This has the advantage that systems can be used
for a particular system which not only allows any desired
transverse spacing of the movable system parts, but also allows
systems to be used whose transverse offsets of the movable system
parts are only possible in one direction.
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. 1 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 branch-track 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 magnetic-shield 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 of a 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. 11 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. 11 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. 2;
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 track 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 its
armature 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
one trace or pathway crosses over a trace or another 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. 1, 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 high-conductivity
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 10 of the vehicle 1 carries two rows 8
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 1 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. 1).
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. 1) 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 still-effective 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 1 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. 13 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 is to 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 of the electromagnet arrangement from its armature
rail. Similarly, as the vehicle leaves the branch, a gradual
increase in the energization of the electromagnet arrangement which
is to become 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 right-hand 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 higherto 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 entirely by 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 syspension
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 only to
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.sub.a. 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.sub.f, the force
relationships in the curve can be represented as P.sub.f = P.sub.a
+ P.sub.fl where P.sub.fl 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 (FIG. 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
left-hand 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/2, 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 25 are provided along the track and the
vehicle in the branch region. The vehicle 1 is here provided with
two one-sided 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 the vehicle 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 (e.g. the
right-hand spur of FIG. 3), the electromagnets 24 and 25 are
preferably offset from one another to provide a lateral 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.sub.i 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 arrangements 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.sub.Fl is directed to
the left (toward the outer limb of the curve) and is balanced by
the control force P.sub.f of the effective electromagnet and guide
arrangement, and a force p.sub.i 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.sub.i. 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. 10 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 10 of the vehicle,
i.e. in the vertical median plane, while a pair of track-support
electromagnet rows 27 are formed upon the track 3', 3" so as to be
offset from the central row of magnets 26 of the vehicle and
provide lateral force components P.sub.i to the left or to the
right as may be required. The leftward component of the force
represented in FIG. 9 is significant only in that it counteracts
the horizontal component P.sub.f developed by the electromagnetic
suspension and guide system 2 and thus permits a relatively stable
state of counteracting forces to develop. In the position shown in
FIG. 10, however, the lateral force component is effective with the
force component P.sub.f to balance the centrifugal force. By
canting the system, so that the weight of the vehicle is carried
somewhat to the right, it is possible to obtain a force component
of the vehicle weight for counteracting the centrifugal force. In
this case, a smaller portion of the centrifugal force need be taken
up by the electromagnetic suspension and guide arrangement 2.
FIGS. 11 and 12 illustrate yet another system for diverting the
vehicle to one side or another. In these embodiments, the vehicle
support electromagnets 26 extending generally centrally of the
vehicle can be shifted laterally to either side of a vertical
median plane by, for example, fluid-responsive means of the type
described for raising and lowering the rails. With this system, the
electromagnets 26 can be aligned with either of the track rows 27
of electromagnets and somewhat offset therefrom, as required, to
direct the vehicle onto one path or another, to vary the supporting
and lateral force contribution, etc. In FIG. 11, row 26 has been
shifted to the left of row 27 of electromagnets. A component
P.sub.a is generated in the direction of the centrifugal force
component P.sub.fl to balance the force P.sub.f of the suspension
arrangement. In FIG. 12, the row 26 of electromagnets lies somewhat
to the right of the right-hand row 27 so that the inward force
component P.sub.i adds to component P.sub.f to balance the
centrifugal force component P.sub.fl. In the embodiments of FIGS. 7
- 12 the support electromagnets may be replaced by permanent
magnets as in FIGS. 1 - 4.
ELECTRODYNAMIC SUPPORT SYSTEM (FIGS. 13 - 15)
FIGS. 13 and 14 show electrodynamic arrangements for supporting the
vehicle 1 along the limb of a curve encountered by the vehicle as
it traverses a branch. In FIG. 13, illustrating the electrodynamic
system at one side of the vehicle, the system is shown to comprise
a row 29 (extending in the longitudinal direction) of coils 30
which have been illustrated only schematically. The coils 30 are
carried by iron cores of U-profile, the shanks or arms 32 of which
straddle the upstanding rail 33 of copper or aluminum. This rail 33
is disposed on edge and can be received between the arms of core
31.
When the coil 30 is energized with direct current, a direct-current
magnetic field bridges the free ends of the arms and has its
magnetic lines of force cut by the rail 33 so that, especially at
high vehicle speeds, a magnetic reaction force is created to urge
the rail and the field coils apart and thereby provide a supportive
force along the outer limb of the curve. The braking force
associated with the electrodynamic system, which would slow the
vehicle down along the outer limb of the curve, must be compensated
for by increasing the thrust of the linear induction motor at this
side of the vehicle, or by providing an additional linear induction
motor as described previously.
When alternating current energization of coil 30 is employed, the
resulting traveling magnetic field provides a thrust in the
direction of vehicle movement and a supporting force is present
even when the vehicle is at standstill. Since the rail 33 projects
upwardly into the downwardly open yoke formed by the core 31, the
rail and core cannot be shifted relatively laterally. Consequently,
means, e.g. a hydraulic system 34, is provided for raising and
lowering this rail. The section to be raised and lowered will, of
course, be that of the region A - C of the layout shown in FIG. 15.
In addition, a swingable section 36 may be provided in the
crossover region and can be displaceable about the vertical axis 35
to align this section with the elevatable rail sections 33 in order
to direct the vehicle along the desired path.
FIG. 14 shows one half (left-hand side) of a system which comprises
two rows 37 of coreless coils 38 on the underside 10 of the vehicle
1, the coils 38 having axes perpendicular to the track 3.
The track is provided with rails 39 juxtaposed with the coils 38
and adapted to be raised and lowered as previously described.
Preferably, the coils 38 are superconductive and are energized by
direct current. The electrodynamic system of FIG. 14 thus provides
an upward supportive force component as previously discussed.
OVERHEAD SUSPENSION SYSTEM (FIGS. 16 - 19)
In FIGS. 16 and 17, there is shown diagrammatically a vehicle 101
provided with an overhead support of an attractive nature along the
outer limb of a curve negotiated by a vehicle (see FIG. 18). The
vehicle 101 may be driven by a two-sided linear induction motor
(FIGS. 1 through 5), by a pair of one-sided linear induction motors
(FIGS. 7 through 12) or by some other convenient system for
supplying thrust to the vehicle.
The track 102 of the vehicle is provided along its channel-like
walls with a pair of armature rails having downwardly extending
pole pieces and cooperating with rows 105 and 106 of electromagnets
mounted on the undercarriage of the vehicle 101. Each row of
electromagnets 105 and 106 comprises a succession of electromagnets
105' and 106', with the cores of the electromagnets alternately
offset to the left and to the right with respect to the pole pieces
of the juxtaposed armature rails 103 and 104. The electromagnets
105' and 106' have U-shaped cores carrying coils on the respective
webs, and upwardly directed shanks or pole pieces which define
electromagnetic suspension and guide gaps with the armature rails,
the gaps being spanned by magnetic fields which support the vehicle
out of contact with the track in accordance with principles already
disclosed. Each of the electromagnet arrangements (103, 105 or 104,
106) provides an upward force component tending to support the
weight of the vehicle and its load and a lateral force component
tending to center the vehicle along the track.
From FIG. 18 it will be apparent that the track can branch by
continuing the rail 103 through the branch location as one rail of
the straight track at the exit end of the junction while the rail
104 diverges and remains a rail of the curve spur. Since the
straight track and the branch must be completed by other armature
rails to provide balanced electromagnet suspension and guide forces
on both sides of the vehicle, the traces of the electromagnetic
arrangements intersect and no rail can be continued through the
intersecting region especially where, as here, the electromagnetic
arrangements are disposed substantially in the plane of the center
of gravity of the vehicle.
According to a feature of this aspect of the invention, the track
is covered, i.e. provided with a roof or vault as represented at
110, at least in the branch region, at which the magnetic support
is provided. Along the upper edges of the vehicle 101, therefore,
the rows 108 and 109 of alternately laterally offset electromagnets
108' and 109' are provided, the pole pieces of which are turned
upwardly away from the roof 107 of the vehicle.
The electromagnets 108' and 109' serve to support and guide the
vehicle temporarily along the outer limb of a curve as the vehicle
is directed through the junction. To this end, the tunnel roof 110
is provided with two spaced-apart armature rails 111 and 112, each
of which extends along an outer trace of one of the vehicle paths
and is designed to cooperate with the respective rows 108, 109 of
the support electromagnets.
In the branch region (FIG. 18), therefore, four armature rails 103,
104, 111 and 112 are provided, of which only two at diagonally
opposite sides of the vehicle are rendered operative depending upon
the direction in which the vehicle is to travel. For example, when
the vehicle is to branch to the right, rails 104 and 111 are
effective (see FIG. 17) while rails 103 and 112 are temporarily
functionless. Conversely, the branching of the vehicle to the left
will require rails 103 and 112 to be effective while the other two
rails are inactive.
When the vehicle enters the junction of FIG. 18 (i.e. is in the
region represented at A'- B'), all of which rows of electromagnets
105, 106, 108, 109 are juxtaposed with respective armature rails
103, 104, 111 and 112 (FIG. 1). As the region A'- B' is passed,
assuming the vehicle is to be diverted to the right (FIG. 18), the
electromagnets of row 105 are progressively deenergized while the
electromagnets of row 108 are energized so that the previous
suspension forces of the magnet 105' is replaced by an attractive
support force at the top of the vehicle as the row of
electromagnets 105 diverges from its rail 103.
When the vehicle is to pass through the junction without deflection
along the right hand spur, electromagnets 109' are energized and
electromagnets 106' are deenergized to replace the suspension and
guide function of the latter with the supporting and guide function
of the former. In the region C' at the exit side of the junction,
the previously inactive suspension and guide electromagnets again
become effective to support the vehicle.
FIGS. 16 and 17 also show that the mutual spacing of the magnet
rows 108 and 109 at the top 107 of the vehicle is greater than that
of the rows 105 and 106 of the suspension electromagnet system. As
a result of C' of the track system (FIG. 18) there is a significant
overlapping of the upper and lower magnetic arrangements and hence
a shock-free transition between the suspension and guide function
and the support and guide functions without requiring that both
upper armature rails 111 and 112 cross each other.
This freedom from crossover of the upper rails allows the system to
be constructed with the configuration shown in FIG. 19 wherein each
row 108, 109 of electromagnets along the upper edges of the vehicle
can be subdivided into two rows of electromagnets, one row directed
upwardly to provide the supporting function while the other row is
turned laterally to provide a guide function, the armature rails
111 and 112 of this embodiment being angle irons with horizontal
faces cooperating with the inwardly facing electromagnets at the
top of the vehicle.
* * * * *