Note: Descriptions are shown in the official language in which they were submitted.
CA 02225040 2000-06-22
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RAIL VEHICLE', COMPRISING A SINGLE-AXLE BOGIE
The invention relates to rail vehicles of the kind in which a wagon body is
mounted upon at least one single axle bogie and is pivotable relative to the
bogie about
a real or virtual vertical axis.
A known rail vehicle of this type (DE 42 24 467 A1) comprises at least two
wagon bodies supported on at least three controlled single-axle bogies. The
control
signals for the control of the plurality of bogies are generated by a control
means, which
derives the control signal fram the angular position of two adjoining wagon
bodies. The
control means in this context comprises a hydraulic adjusting unit coupled to
the bogies
and the control signal obtained from the angular position of adjoining wagon
bodies by
a transmitter sensor unit and therefore depending on the curved radius of a
track to be
travelled through, transposes a functional horizontal turning of the relevant
bogies around
a vertical axis. A dis;~dvantage of this embodiment resides in a complex
energy supply
requiring a hydraulic installation on the wagon in addition to an electric
power supply.
Moreover, scanning of the angular position of two adjoining wagon bodies is
performed
via mechanical lever iFormations, acting on relevant hydraulic control
elements guiding
the specific bogie chassis into a desired position.
An object of the present invention is to eliminate or at least mitigate these
disadvantages.
According to the present invention, there is provided a rail vehicle
comprising at
least one single-axle bogie, pivotally mounted to an associated wagon body for
rotation
around a real or virtual vertical axis in relation to said wagon body under
the control of
a control unit (15) in response; to a quasi-static signal (w(t)) provided by a
transmitter
sensor unit (14) in dependence upon the radius of curvature of a track to be
travelled
upon, wherein the transmitter sensor unit (14) comprises an electric
transmitter sensor
(17) and an electric low-pass filter (18), the transmitter sensor (17) emits a
dynamic
electric basic signal (w(t)dy~ and the low-pass filter (18) filters this basic
signal (w(t)dY,~
to produce the quasi-static signal (w(t)) for supply to the control unit (15)
for control
thereof.
Such an arrangement facilitates reliable adjustment of a singe-axle bogie by
simple control means.
In a preferred nmbodirr~ent of a rail vehicle according to the invention an
electric
source signal is generated by means of a transmitter sensor in a transmitter
sensor unit,
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derived directly from the radius of a track to be passed through, resulting
from the
current position of a bogie, more particularly a bogie further ahead which is
self-adjusting due to the whe<~l-rail-geometry, from the angular position of
adjoining
wagon body parts or the like. Besides a useful signal component required for
the control
and corresponding to the radius of curvature, this source signal further
includes
superimposed oscillations, which, in a rail vehicle in operation, come about
by swaying
between the bogie and the wagon body or between the wagon bodies used as a
measuring
basis, as a result of uneven surfaces, foreign bodies, traction force
influences and the
like, modulating or superimposing themselves on the curve-dependent useful
signal. In
order to eliminate such interference unrelated to the track curvature, the
source signal
is passed to a low-pass filter comprising a limiting frequency below the
interfering
oscillations. It has been found that this critical frequency is below 5 Hertz
and is
selected preferably up to 0.5 Hertz. The signal thus freed from interfering
oscillations
corresponds to a set value-signal adjusted in each case to the curve radius to
be
negotiated, serving as a quasi-stationary command signal for the control of a
control unit
assigned to the bogie to be adjusted.
The control unit coupled to the bogie to be controlled, in particular its
bogie
chassis, then may cornpr-ise a;n electric control means and an electromagnetic
control
element controlled by the source signal of the said electric control means
acting as a
command signal. This control element is, on the one hand, mechanically coupled
to the
bogie and, on the other hand., to the associated wagon body so that by
adjusting the
control element swivelling of the bogie around its actual or virtual vertical
axis is
possible. If a stepping motor is used as a control element, it may suffice to
transpose
the output signal of the filter via the controlling means into a control
impulse sequence
causing an angular shift of the bogie, adapted to the radius of curvature to
be negotiated
in relation to the associated wagon body. If, on the other hand, a
positionally accurate
control is not ensured., it will be advantageous to provide a position
indicator on the
control element or on the bogie, supplying an electric position signal
regarding the
current adjusting position. This position signal may then be conveyed as the
actual
position value to an electric comparator, to which the quasi-stationary output
signal of
the filter is fed as the set value, the deviation resulting from the set value
and the actual
value, in each case stiill to be compensated for, being fed to the controlling
means the
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output signal of which is emitted to the control element as the control signal
until such
time as the deviation moves a~. le:ast approximately towards zero.
The transmitter sensor unit and, in particular, the filter may comprise two
quasi-
static signal output terminals, in which case two of such control units are
provided, each
connected to a respecaive one of these signal output terminals, the respective
control
elements of the two control units jointly acting upon the same bogie and in
particular
upon its bogie chassis. The rr~echanical engagement points of the two control
elements
preferably are diagon~~l to one: another and in the regions of the bogie
chassis wherein
the secondary spring elements are accommodated for connecting the bogie
chassis to the
associated wagon body. In this region normally also primary spring elements
are
provided between the bogie chassis and the wheel bearings of the single-axle
wheelset.
The transverse rigidity of these spring elements effects the basic alignment
of the bogie
in relation to the longitudinal) axis of the vehicle and in operation allows a
limited
deflection of the whec:lset resulting from the wheel-rail-geometry, while the
deflection
forced by the control element takes place against the force of the secondary
spring
elements. Advantageously, in this case a pivot pin bearing forms a real
vertical axis for
the swivel movement of the bogie in relation to the wagon body.
The control elf;ment may be linearly driven and may be an electric linear
motor
or a servo-motor with threaded spindle drive or planetary drive. The
connection of the
control elements) to the bogie or the wagon body preferably is performed
resiliently,
for which purpose interposed rubber-metal elements preferably are used in
order, on the
one hand, to protect the control element against impact stresses, and to allow
necessary
reciprocating moveme~.nts between the bogie chassis and the wagon body
resulting from
the driving operation.
The transmitter sensor for the generation of the rail curve-dependent output
signal
may be assigned to a coupling; joint between two wagon bodies, taking the form
of an
electric impedance unit, and may record the angular displacement for the
output signal
coming about during curved travel as a changing electric resistance,
inductivity or
capacity value, or the like. The transmitter sensor may, however, be assigned
to a bogie
preceding or succeeding the bogie to be controlled and be provided on the same
or
another wagon body, influenced by the swivel deflection resulting
automatically from the
wheel-rail-geometry when negotiating a curve.
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An embodiment of the invention will now be described, by way of example only,
with reference to the accompanying drawings, in which:-
Figure 1 illustrates a single-axle bogie to be controlled by the radius of
curvature
to be negotiated by means of servo devices in plan view; and
Figure 2 is a block schematic diagram of a control unit including a sensor
unit
and servo units for controlling; the servo devices.
A wagon body, not illustrated, of a rail vehicle rests on a bogie chassis 2 of
a
single-axle bogie via secondary spring elements 1 comprising only one axle 3
having rail
wheels 4, rigidly mounted on the axle 3. The axle 3 of the wheelset 3, 4 is
positioned
in a vertical plane, extending transversely to the longitudinal direction of
the vehicle and
including the vertical <;entral aces 5 of the secondary spring elements 1, in
which context
the wheel bearings 6 .are supported and fitted on the underside of the bogie
chassis by
primary spring elements 7, preceding or succeeding the former in the direction
of travel.
The primary spring elements ~~ in this case not only absorb weight forces in
their axial
direction but, due to .a certain transverse resilience, allow, to a limited
extent, swivel
deflections of the axle 3 or the; bogie 2 in relation to the wagon body 13
resulting from
the wheel-rail-geometry. Swivelling in this case is performed around a
vertical axis 8,
carried out by an axle journal connected to the associated wagon body and
engaging in
a support for the bearings on l:he bogie chassis 2.
In order to bring about a forced swivel displacement of the bogie around the
vertical axis 8, depending on the radius of curvature of the respective rail
section to be
passed, a control unit, comprising two diagonally and symmetrically disposed
control
elements, i.e. servo devices 9, is provided, which, on the respective outer
side of the
bogie chassis 2 in the region of the wheel bearings 6 or the secondary spring
elements
1 is in engagement with an adjusting rod 10 having a holding lug 11 provided
there and,
at the other end, is til;htly connected to a wagon body part 13, rigidly
disposed on the
wagon body as an elastic connection means 12 by a rubber elastic element.
As shown in Figure 2, the control unit also comprises means for the control of
the servo devices 9. Thus, the control unit comprises a sensor unit 14 and two
servo
units 15 controlled thereby, identical at least in their basic function, each
comprising one
of the servo devices 9 for the forced swivel displacement of the bogie 2, 3.
The sensor
unit 14 comprises in this context a transmitter sensor 17 supplying the basic
signal as a
function of the radius of a track curve to be negotiated, generated depending
on a further
CA 02225040 2000-06-22
auto-adjusting bogie according; to the wheel-rail-geometry or according to the
angular
position in relation to one another of wagon body parts of adjoining wagons.
As these
transmitter means are not only affected by the radius of the track to be
travelled on but
also by interference factors, an interference signal, resulting from the
dynamics of
5 vehicle movement is superimposed upon the curve-dependent signal portion.
The
transmitter sensor 17 ;accordin;gly supplies a dynamic basic signal (w(t)dy,~
to a low-pass
filter 18 having an upper limiting frequency of up to 5 Hertz, preferably,
however, of
only 0.5 Hertz. The contributions of faster, higher frequency interference
oscillations
are thus eliminated from the basic signal so that at the filter 18, output
comprising
preferably two separate output terminals for the two servo units 15, a quasi-
stationary
control value (w(t)) is set up serving as the set value for the adjustment of
the servo
devices 9. For this purpose; the filtered control value (w(t)) is fed by way
of a
comparator 20 to a regulator 1.9 supplying an output signal (y(t)) as the
adjusting value
for the electro-mechanical servo device 9. According to the magnitude or
duration of
this signal, the servo device 9, comprising in particular an electric motor,
performing
a longitudinal shift to swivel the bogie, controls the bogie 1, 2 in such a
manner that the
axle 3 is in a radial line of the track section to be travelled on. In order
to ensure in this
case that the desired position of the control element or of the bogie is
indeed attained,
a position indicator 21 supplies, a position signal (xr(t)) as a function of
the swivel setting
of the bogie 2, 3. The position indicator may be coupled directly to the bogie
2, 3, or
to the servo device 9, in the latter case to detect the position of the
adjusting rod 10.
This position signal (xr(t)) is passed to the electric comparator 20 for
comparison with
the filtered control value (w(t)). The position signal is therefore the
actually attained
actual value in relation to the desired position predetermined by the desired
value. In
the comparator 20, the deviation is calculated on the basis of both input
signals (w(t))
and (xr(t)) and fed to the regulator 19 as input signal (xW(t)). The regulator
19 thus
generates the output signal (y(t)) only until the desired value signal and the
actual value
signal in the comparator 20 lead to a regulating deviation close in value to
zero. The
position indicator 21 may, for example, be an adjustable electric resistance,
mechanically
connected, on the one hand, to the bogie chassis 2 and, on the other hand, to
a stationary
wagon body part 13 and supplying the control signal (xr(t)) resulting from the
swivel
displacement of the bogie 2., 3.
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The sensor unit 14 nnay also be used for the purpose of storing the rail
configuration against .distance in a data base as the filtered control signal
for the entire
section, for example, during a test drive on a predetermined rail section and
calling up
from this data bank the quasi-stationary control value (w(t)) for the control
of servo units
15 during further rides on this. section.
As a whole, the design of the servo devices on an electric and electronic
basis
results in a cost-effective and compact construction with minimum
expenditures, the
electrical network on rail vehicles being available in any case for the
electrical power
supply. Electric inter:Ference independent of the radius of the rail section
to be travelled
on, is eliminated by simple electric filtering expedients so that a precise
radial alignment
of the bogie in relation to the tracks may take place free from interference,
thus attaining
a quiet and derailing-proof running of the respective bogie. It is in this
context likewise
possible to transmit the rail curvature identified by the sensor unit to a
plurality of
bogies. It may in this case further be advantageous to call up a curve-
dependent dynamic
basic signal on the actual bogie to be controlled, for example, when the
transmitter
sensor records the relative disvplacement between the bogie chassis 2, 3 and
the axle 3
mounted therein, accordingly bringing about via the servo devices on the
associated
bogie an overall adjustment of the bogie 2, 3 into a swivel position in which
the
deflection of the wheelset 3, 4 resulting from the wheel-rail-geometry, made
possible by
the primary spring elements 7 is compensated for in relation to the associated
bogie
chassis 2. On the whole, a good radial adjustment of single wheelset bogies in
the track
curve comes about even in the event of large wheelset spacings on a wagon
body, in
which context the control means to be used are more cost-effective than the
provision of
a second wheelset to take over the control functions. Moreover, the axle 3
also carries
brake disks 22 to which disk brake mechanisms 23 are assigned, mounted on the
bogie
chassis 3.
