U.S. patent number 3,780,668 [Application Number 05/280,073] was granted by the patent office on 1973-12-25 for electromagnetic suspension and/or guide system especially for magnetically suspended vehicles.
This patent grant is currently assigned to Krauss-Maffei AG. Invention is credited to Gerhard Bohn, Helmut Schauberger, Peter Schwarzler.
United States Patent |
3,780,668 |
Schwarzler , et al. |
December 25, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
ELECTROMAGNETIC SUSPENSION AND/OR GUIDE SYSTEM ESPECIALLY FOR
MAGNETICALLY SUSPENDED VEHICLES
Abstract
An electromagnetic suspension and guide system for magnetically
suspended vehicles comprises a support or track along which the
vehicle is displaceable and is provided with an armature rail of
magnetically permeable material (e.g., a ferrous metal), while the
vehicle is provided with at least one electromagnet cooperating
with this armature rail. The electromagnet has a core of U-profile,
the arms or shanks of which reach toward the armature rail which is
likewise of U-profile whose shanks reach toward the electromagnet.
The shanks of these two members overlap and the shanks of one
member are inclined toward the shanks of the other. The shanks of
the armature member may reach into the space between the shanks of
the core member or vice versa.
Inventors: |
Schwarzler; Peter
(Furstenfeldbruck, DT), Bohn; Gerhard (Munich,
DT), Schauberger; Helmut (Munich, DT) |
Assignee: |
Krauss-Maffei AG (Munich,
DT)
|
Family
ID: |
5819644 |
Appl.
No.: |
05/280,073 |
Filed: |
August 11, 1972 |
Foreign Application Priority Data
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Sep 7, 1971 [DT] |
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P 21 46 143.8 |
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Current U.S.
Class: |
104/286; D12/37;
D12/40; D12/49; 104/281 |
Current CPC
Class: |
B61B
13/04 (20130101); B61B 13/08 (20130101) |
Current International
Class: |
B61B
13/04 (20060101); B61B 13/08 (20060101); B61b
013/08 () |
Field of
Search: |
;104/148MS,148SS,148LM
;308/10 ;335/219,281,299,297 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1,035,764 |
|
Jul 1966 |
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GB |
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707,032 |
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Mar 1941 |
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DD |
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643,316 |
|
Aug 1934 |
|
DD |
|
Primary Examiner: Reger; Duane A.
Assistant Examiner: Barefoot; Galen L.
Claims
We claim:
1. An electromagnetic suspension or guide system, comprising
support, a U-profile armature rail member fixed to said support and
having a web and a pair of shanks extending from said web, and
electromagnet juxtaposed with said rail member and having a core
member provided with a web and a pair of shanks extending therefrom
toward said rail member, and a coil wound on said core member, the
shanks of one of said members being received between the shanks of
the other of said members and overlapping therewith, and at least
one shank of each overlapping pair being inclined to the other.
2. The system defined in claim 1 wherein the shanks of said core
member extend into said rail member between the shanks thereof.
3. The system defined in claim 1 wherein the shanks of said rail
member are received between the shanks of said core member.
4. The system defined in claim 1 wherein the inclined shank of each
of said pairs is of curved configuration.
5. The system defined in claim 1 for a magnetically suspended
vehicle wherein said support is a longitudinally extending track,
said rail member extends longitudinally along said track, said
system further comprises a vehicle carrying said electromagnet and
displaceable along said track, said core member and said rail
member having centroids defining a longitudinal axis of stability
such that relative displacement of said vehicle and said support
tending to separate said core member from said rail member in the
direction of said axis results in a magnetic attractive force
counteracting such separation, and a further electromagnetic system
effective between said support and said vehicle for stabilizing
same against relative displacement in a direction transverse to
said longitudinal axis.
6. The system defined in claim 5 wherein said rail member and said
core member form a longitudinally stable suspension arrangement for
said vehicle, said further electromagnetic system including a
control arrangement for limiting lateral displacement of said
vehicle and being electromagnetically unstable in the absence of
said control arrangement.
7. The system defined in claim 5 wherein said rail member and said
core member provide a longitudinally stable lateral guide
arrangement for said vehicle and said further electromagnetic
system is an unstable electromagnetic suspension including a
control arrangement for adjusting the suspension gap of said
vehicle.
8. The system defined in claim 5 wherein said armature rail member
is provided with a pair of inclined shanks having free ends
approaching the shanks of said core member and the shanks of said
core member are mutually parallel.
9. The system defined in claim 5 wherein said core member is
provided with the inclined shanks having free ends approaching the
shanks of said rail member and said rail member has mutually
parallel shanks.
10. The system defined in claim 5 wherein the inclined shank of
each pair includes an angle between substantially 15.degree. and
60.degree. with the other shank of the pair.
Description
FIELD OF THE INVENTION
The present invention relates to magnetic suspension and guide
systems and, more particularly, to an electromagnetic suspension or
guide system for magnetically suspended vehicles.
BACKGROUND OF THE INVENTION
In recent years considerable effort has been expended in attempts
to devise mass transportation and high-speed transportation systems
without the disadvantages of conventional arrangements. For the
most part, any transportation system of this type must comprise a
track or support which is located above grade, at grade level or
below grade, and a vehicle displaceable along this track. One of
the principal disadvantages of conventional vehicular systems of
this type is the friction between the vehicle and the track.
More recent developments have made use of air cushion tenchiques
for suspending the vehicle or supporting the vehicle upon the
track, this system having the disadvantage that displacement of air
in large volumes is required to maintain a stable air cushion in
the gap between the vehicle and track. The displacement of air in
this manner is noisy, requires bulky equipment and is not desirable
in many urban centers.
The displacement of vehicles along a track may make use of
fluid-pressure differentials, linear-induction motors and other
non-contact or limited contact motive systems, i.e., systems in
which frictional contact between the vehicle and track is
minimized. However, unless the supporting and guiding functions are
also frictionless or of limited friction, the practical vehicle
speed remains limited.
The present applicants and others have disclosed heretofore
magnetic suspension systems whereby the disadvantages of some of
the earlier vehicle-support and vehicle-guide arrangements can be
overcome. In general, a magnetic suspension and guide system may
include one or more armature rails extending along the track and
one or more electro-magnets carried by the vehicle and having cores
cooperating with the armature rails of the track or support to
maintain an air gap therewith across which magnetic force supports
the vehicle. A magnetic-flux path is closed between the poles of
the electromagnet core through the armature and across the gap.
In prior-art magnetic suspension systems, especially for
magnetically suspended vehicles, the armature was a flat bar and
the system was characterized by an unstable force characteristic.
When the system was used as a suspension arrangement, therefore,
the vehicle could be laterally and longitudinally dislocated or
shifted by such forces as wind, centrifugal force as the vehicle
passes around a curve etc., without significant controllability.
When the system was used for guiding purposes, some freedom of
movement is provided in the parallel power to the plane of the air
gap and hence an unstable condition is created in this situation as
well. In order to avoid this instability with two degrees of
freedom, electronic control was necessary for each degree of
uncontrolled movement. In other words, electromagnets were provided
to adjust both lateral and vertical air gaps and to limit the
displacement of the vehicle in the vertical and lateral directions,
and even to stabilize the vehicle against displacement in a
longitudinal mode. For each electromagnet system a separate gap
detector and feedback circuit was provided to regulate the
energization current through the respective coil to maintain the
gap at desired level.
As a result, the electronic control system for conventional
magnetic suspensions having two or more degrees of freedom or
instability was highly complex, expensive and massive, thereby
decreasing the carrying capacity of the vehicle and increasing the
operating and capital cost.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide a
magnetic suspension and guide system, preferably for the
contactless support and/or guidance of a vehicle whereby the
control-system costs can be held relatively low.
It is another object of the invention to provide an improved
magnetic suspension and guide system whereby the aforedescribed
disadvantages can be obviated.
Still another object of the invention is to provide a magnetic
suspension and guide system for a magnetically suspended vehicle in
which fewer gap-responsive control circuits are necessary to limit
instability.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are
attained, in accordance with the present invention, which comprises
an electromagnetic suspension and/or guide system, especially for
magnetically suspended vehicles adapted to travel along a support
track, which comprises at least one armature rail extending along
this track and having a web from which a pair of shanks reach
toward a portion of the vehicle, and at least one electromagnet
whose coil member is of U-profile with a pair of shanks reaching
toward the armature member, the shanks of one of these members
being inclined toward the shanks of the other member and
overlapping the same. A coil is wound upon this core.
More specifically, the armature member is constituted substantially
of a U-cross-section channel whose lateral shanks or arms are
spaced from overlapping with the lateral shanks or arms of the
U-cross-section electromagnet core whereby the shanks of one of
these members is received between the shanks of the other member.
The shanks of one of the members, moreover, are inclined toward the
shanks of the other member so that the region of overlap has a
location of closest approach at which the inclined shanks are
closest to a flank of the noninclined shank or the shank with which
they overlap proximally of the web and divergent from this shank in
the direction of its free end. Between each inclined shank and the
noninclined shank of the other member, therefore, a wedge-shaped
air gap is provided.
A system of this type develops an attractive force in the direction
of the longitudinal axis in which the center of gravity of the
cross-sections or profiles (centroids) lie and which maintains
stability along this longitudinal axis over a limited range of
positions of the electromagnet.
This system is defined as a system having longitudinal stability,
i.e., without change in the electrical current traversing the
electromagnet, the magnetic force resisting displacement along the
longitudinal axis increased with displacement to provide a
so-called force characteristic which has a "spring constant"
similar to the force characteristic of an extension spring which is
deformed.
The increasing magnetic attraction with separation of the
interfitting core member and rail member results from the fact that
the magnetic flux bridging the air gap between the two shanks of
each overlapping pair is a stray flux which is unconcentrated over
the full length of the shank. As the degree of overlap is reduced,
the stray flux is reduced and the flux density at the reduced
regions of juxtaposition (poles) increases.
The force characteristic reaches its maximum when overlapping
practically ceases, i.e., at the point at which the free end of the
arms of the yoke or core of the electromagnet and the free ends of
the arms of the armature rail lie in a common plane perpendicular
to the longitudinal axis defined by the centroids. At this point of
total separation, increased adhesive force with increasing
displacement no longer develops and the magnetic suspension is no
longer stable even in one direction. With overlapping of the shanks
and interfitting of the two channel-shaped members, the system is
transversely unstable, this degree of instability remaining when
the two components of the system are separated. The transverse
instability is seen in the fact that a displacement of the core
member relative to the rail member in a direction perpendicular to
the plane of the longitudinal axis defined by the centroids of the
profile sections, is not magnetically resisted by the flux
traversing the core and rail members.
It is, therefore, a feature of the present invention to provide a
further electromagnetic system, preferably including a magnetic
armature rail and electromagnet, which is effective in the
transverse direction for limiting such displacement. The further
electromagnetic system may be provided with a gap sensor or
detector for adjusting the electromagnetic force to compensate for
or resist the transverse forces. It should be understood that an
arrangement of this type uses control circuitry only for one degree
of possible vehicle displacement, since any tendency for the
vehicle to shift with the other degree of freedom is counteracted
automatically because of the inclined orientation of the shanks of
the armature or core. In practice, it has been found that the
control circuitry need only respond to minor vehicle displacements,
e.g., to damp vehicle oscillation.
Another advantage of the present system resides in the relatively
large freedom of movement of the magnetically suspended system in
the longitudinal direction by comparison with systems using flat
armatures. The system of the present invention can thus provide
tracks, rails and like structures which interact with mating
facilities of the vehicle with larger tolerances than is possible
with the prior art arrangements.
The electromagnet of the present invention may be made relatively
wide with relatively short lateral shanks or arms such that the
lateral shanks or arms of the armature can be received between the
shanks or arms of the electromagnet core. A system of this type is
characterized by reduced stray flux between the relatively widely
spread lateral shanks of the magnet core, by the ability to use
wide electromagnet coils and hence by a reduced coil-winding
height.
When the system of the present invention provides lateral shanks or
arms of the armature which embrace the arms of the electromagnet,
the active surfaces of the armature and the magnet core is
protected from ice, contaminants and the like in a particularly
convenient manner.
It has been found, moreover, that it is possible to vary the spring
constant and the force characteristic of the system by imparting a
curvature to the inclined shank or arm, e.g., by curving the latter
more rapidly away from the non-inclined shank or curving it toward
the latter. When the system is used for suspension, a stiffer or
softer spring characteristic can be provided with increasing
load.
It has been found to be advantageous, moreover, to provide the
longitudinally stable suspension or guide system for stretches
which are relatively stiff and hilly as a suspension system, but as
the guide system where the vehicle is expected to travel around
large numbers of relatively sharp curves. These preferences are a
consequence of the high degree of longitudinal adjustability
afforded by the system of the present invention .
DESCRIPTION OF THE DRAWING
The above and other objects, features and advantages of the
invention will become more readily apparent from the following
description, reference being made to the accompanying drawing in
which:
FIG. 1 is a vertical cross-sectional view through a portion of a
suspension system embodying the invention, the means for attaching
the components to the respective supporting structure being
illustrated diagrammatically;
FIG. 2 is a view similar to FIG. 1 of a suspension and guide system
representing a variation of the system of FIG. 1;
FIG. 3 (sheet 2 of the drawing) is a view similar to FIGS. 1 and 2
but illustrating a kinematic reversal of the components in a
suspension or guide system according to the invention;
FIG. 4 is a view similar to FIG. 3 of still another embodiment of
the invention;
FIG. 5 (sheet 1 of the drawing) is a further diagrammatic
cross-sectional view, taken in a plane perpendicular to the
direction of movement of a vehicle provided with the suspension or
guide system and illustrating another aspect of invention;
FIG. 6 (sheet 1 of the drawing) is a view similar to FIG. 5 showing
another modification;
FIG. 7 (sheet 3 of the drawing) is a vertical cross-section through
a suspension system for a magnetically suspended vehicle in which
the longitudinal stability is provided in the suspension portion of
the system;
FIG. 8 is a view similar to FIG. 7 of an embodiment of the
invention wherein the longitudinally stable electromagnetic system
is provided for guiding the vehicle;
FIG. 9 is a side elevational view of one of the electromagnets in
accordance with the invention; and
FIG. 10 is a diagrammatic perspective view of a vehicle system
embodying the invention.
SPECIFIC DESCRIPTION
Referring first to the overall view of a vehicle system according
to the present invention shown in FIG. 10, it can be seen that the
system may comprise a substantially horizontal support track 50
held at intervals by pylons 51 or other suppor means at grade
level, above grade or below grade. The track 50 is provided with a
channel 52 which is upwardly open and is overhung by a pair of
inwardly turned flanges 53 and 54.
As will be described in greater detail in connection with FIGS. 7
and 8, the undersides of the flanges 53 and 54 are provided with
respective downwardly open channels 55, 56 constituting armature
rails composed of a fellow magnetic material, e.g., iron, and
extending the full length of the track. When, as described below,
longitudinal stability of the suspension portion of the system is
desired, the rails may have the configuration of any of the rails 1
of FIGS. 1 through 7. However, when guide stability is required,
the rail configuration may be that of FIG. 8.
The inwardly turned facrs of the flanges 53 and 54 are also
provided with inwardly open rails 57 and 58 of U-section as also
will be described in greater detail in connection with FIGS. 1
through 8.
The vehicle 60 may comprise an operator compartment 61 and a
passenger compartment 63 to which axis is had through a door 63.
The vehicle may be propelled by a linear induction motor and it
receives electrical power through brushes provided on the vehicle
and contact rails provided on the support tract 50 in accordance
with conventional practices.
The vehicle is provided with a horizontal flange 64 which extends
into the channel 52 and carries on its outer edges the
electromagnets 65 and 66 cooperating with rails 55 and 56 for
suspension of the vehicle. Outwardly facing electromagnets 67 and
68 are also provided upon the vehicle to cooperate with the
armature rails 67 and 68 in guiding the vehicle.
The vehicle is magnetically suspended from the downwardly open
U-section rails 55 and 56 and is guided against lateral movement by
the electromagnetic forces generated at rails 57 and 58. The result
is a frictionless magnetic suspension and guide system.
In FIG. 1, the electromagnetic suspension or guide system is shown
in greater detail and the principles of operation will become more
fully apparent.
Thus, the electromagnetic suspension or guide system, which may be
used for the suspension or guide arrangement of FIG. 10, can
comprise a fixed armature rail 1 with a substantially U-shaped
corss-section whose lateral flanges, shanks, or arms 2 to define
obtuse angles .alpha. with the web 3. These angles, greater than
90.degree. as illustrated in FIG. 1, are designed to provide
divergency in the direction of the fixed rail between the arms or
shanks of substantially 15.degree. to 60.degree., or a convergency
in the direction of this fixed rail of a similar angle as will be
apparent hereinafter.
On the vehicle 4 to be suspended or guided, there is mounted an
electromagnet 5 whose elongated core 6 has a U-shaped profile and
carries a coil 8 wound about the web 7.
The arms or lateral shanks 12 of the core 6 reach upwardly to
bracket the arms 2 of the rail 1 between them, i.e., the armature
rail 1 and the core 6 overlap or interfit with the arms 1 received
with the channel or between the arms of the other.
When the coil 8 is electrically energized, a magnetic flux 9 (shown
in broken lines) is induced in the core 6, the flux path closing
through the air gap between the arms 12 of the core 6 and the arms
2 of the rail 1 and through the latter.
The magnetic attractive force at the gaps, produced by the field 9,
and the lateral guide force represented at 10 (see also FIGS. 7 and
8) produced by some other means, e.g., another electromagnet and
rail arrangement, maintains the vehicle in the position illustrated
in FIG. 1 relative to the rail, thereby freely suspending the
supported or guided system represented at 11.
As already noted, the lateral flanges, arms or shanks 2 and 12 of
the armature rail 1 and the core 6 overlap in this position and
define gaps between them which diverge in the direction of the
support structure. Of course, it is not critical to the present
invention that the direction of divergence be toward the support
structure it being only significant that the direction of
convergence be such that a tendency toward separation will reduce
the volume of the air gap between the two members. The inclined
orientation of one of the pairs of lateral arms (in this case the
arms of the rail) to the mutually parallel arms of the other pair
results in an increasing attractive magnetic force between the
cores 6 and the rail 1 with increasing separation (i.e., with
increasing withdrawal of the interfitting parts) to a maximum
attractive force at the point that overlap ceases or the poles
formed by the ends of the arms become substantially coplanar. At
this point, the suspension or guide system becomes unstable as in
conventional magnetic suspensions in which the electromagnet
cooperates with a flat-strip armature.
If the centers of gravity of the armature rail and the
electromagnetic core in any sectional plane perpendicular to the
direction of movement of the vehicle and to the longitudinal
dimensions of these magnetic members,i.e., the centroids of the
sections, are considered to define a longitudinal axis 13 (FIG. 1),
it is possible to define the overlapping or interfitting
relationship as one which is longitudinally stable without the use
of a gap detector or other control arrangement to compensate for
increasing separation along this axis.
In other words, a longitudinally stable system, within the meaning
of the present invention,is one which compensates automatically for
a tendency toward separation of the parts by increasing the
magnetic attractive force resisting such separation without a
concommitant increase in the electrical energization of the coil.
The system of FIG. 1 thus provides increasing magnetic attractive
force to resist separation in the direction of the axis 13 until
the point of withdrawal is reached.
In the system of FIG. 1, however, a transverse stability (against
this location forces in the direction of arrows 10) is not present,
i.e., any shift of the system to the left or to the right from the
median position shown will not be magnetically resisted by the
field 9, but rather will be enhanced so that the system must be
laterally stabilized by some external or other means as represented
by the forces at 10.
In the system of FIG. 2, the mutually parallel lateral arms, flanks
or shanks 12 of the electromagnetic core 6 reach into the channel
formed by the armature rail 1 between the inwardly turned arms 2 of
the latter. The arms 2 include angles .alpha. of less than
90.degree. such that the arms will include the desired angle
between 15.degree. and 60.degree. with the arms 12. The overlapping
or interfitting relationship which is thus obtained ensures
longitudinal stability as described earlier.
FIGS. 3 and 4 represent systems which are kinematic reversal of the
systems of FIGS. 1 and 2. In FIGS. 3 and 4 the arms of the core 6
are inclined inwardly (FIG. 3) or outwardly (FIG. 4) toward the
mutually parallel arms 2 of the armature rail 1. The arms of the
latter are thus received with an overlap between the arms of the
electromagnetic core 6 (FIG. 3) or receive the arms of the core
(FIG. 4). The latter systems, which function as described for the
system of FIG. 1, have the advantage that a single armature rail
structure can be used for a variety of configurations of the magnet
or magnet core.
One of these is desired to modify the force characteristic of the
system i.e., the magnetic force versus displacement in the
direction of the axis 13, the inclined shanks or arms may be
oriented to provide the desired characteristic. For example, in
FIG. 5 there is shown a system in which the arms 2 are provided
with an outwardly concave curvature i.e., a curvature which is
convex in the direction of the centroids. This curvature which may
be generally cylindrical, pyramidal or otherwise conformed to a
surface of revolution with an axis parallel to the longitudinal
direction, results in an increase in the "spring constant" of the
system with increasing longitudinal displacement, i.e., the elastic
suspension of the floating system becomes stiffer with greater
loads. When the inversed effect is desired, the system of FIG. 6
may be employed in which the arms are concaved toward the centroid
of the armature rail. The term "spring constant" is used herein to
refer to the relationship between restoring force and displacement
which, generally speaking, can be represented by a relationship
such as F = Kx where x is the displacement and F is the restoring
force. The constant K is thus defined as F/x and is analogous to
the usual spring constant. With increasing K, the system becomes
stiffer.
In FIGS. 7 and 8, there are shown two arrangements of the
longitudinally stable suspension and guide arrangements of FIGS. 1
through 6. These systems respectively provide a longitudinally
stable suspension with an unstable system providing lateral control
and an unstable suspension system with a longitudinally stable
guide system for lateral control.
The system of FIG. 7, for example,comprises a support track 14
along which a vehicle 15 is displaceable. Along the undersides of
the inwardly turned flanges of the track, there are provided a pair
of longitudinally stable electromagnetic suspension systems 16 (see
FIG. 1) while the guide systems are longitudinally unstable and are
provided at 17. The unstable systems 17 each comprises an armature
rail 18 and electromagnets 19 with U-profiles whose arms are
parallel and aligned one another so that they are juxtaposed
without overlap. The electromagnets 20 of these systems are
provided with gap detector in their respective control circuits 100
to maintain the optimum gap. However, vertical control circuits are
not necessary because of the automatic adjustment of the magnetic
adhession force to increasing displacement in the vertical
direction.
A converse system is shown in FIG. 8 in which the longitudinally
stable system 21 is provided for guide purposes in combination with
longitudinally unstable suspension systems 22, the latter being
connected with a control 200 to maintain with optimum suspension
gap. The guide systems automatically operate to center the vehicle
against lateral forces, e.g., from wind or the centrifugal effect
of a turn or bend in the track without a control circuit.
* * * * *