Method of influencing the inflection angle of railway vehicle wagons, and railway vehicle for carrying out this method

A multiple-unit railway vehicle having three car bodies where the respective neighboring car bodies are each connected in a pivoting manner to one another by means of a single coupling, and each car body sits only on one two-axle truck. In the vicinity of the respective center pivot and possibly also on the trucks, there are actuator elements that are used to influence the articulation angle between the longitudinal axes of the car bodies. To control the articulation angle so that when the train is traveling over a curved segment of track, the car bodies assume a position in relation to one another that corresponds at least to a significant extent to the static rest position of the railway vehicle on the corresponding section of track, the profile and curvature of the track are determined during travel for the segment of the track that currently lies between the first and last trucks, and from that measurement, the set point position is determined, and by means of the actuator system measurements are taken to counteract at least an overshooting or undershooting of the set point value.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a method for influencing the articulation angle 
between the longitudinal axes of neighboring car bodies of a multiple-unit 
railway vehicle traveling on a track and a railway vehicle for the 
implementation of this method. 
2. Description of the Prior Art 
To influence the articulation angle between the longitudinal axes of 
adjacent car bodies of a multiple unit railway vehicle traveling on a 
track, the prior art (DE 28 54 776 A1) teaches that the torsion of the 
longitudinal axis of a car body is measured with respect to the 
corresponding truck, and as a function of said measurement, a system of 
actuators in the form of hydraulically pressurized cylinders is controlled 
by means of a control unit. This system of actuators acts electrically on 
the control unit and mechanically between the ends of the neighboring car 
bodies that are connected to one another by means of a single center 
pivot. The system of actuators is controlled so that the two-axle trucks, 
which do not have a truck center pin and on which the car bodies are 
supported by means of elastic secondary springs, are completely freed of 
the function of force dispensers, and the wear of the wheel flanges and 
the rails is significantly reduced. In this case, when the train is 
traveling on a straight section of track, the system of actuators blocks 
the center pivot in one position over the center of the track, and when 
the train rounds a curve, forces the center pivot to buckle toward the 
outside of the curve of the track. The purpose of this restricted 
excursion is to achieve an improved utilization of the clearance when the 
railway vehicle is traveling around a curve. 
One disadvantage of this arrangement and method is that it requires a 
permanent and restricted control of the center pivot, because the forces 
resulting from the buckling must be completely isolated from the truck. 
SUMMARY OF THE INVENTION 
The object of the invention is to create a method and railway vehicle which 
make it possible to control the car bodies so that during dynamic travel, 
the car bodies are in a position in relation to one another which 
corresponds to the static position in the corresponding track segment. 
In a method and a configuration as claimed by the invention, the curvature 
of the track in the vicinity of the contact points with the truck is 
determined from the articulation angle at the center pivot measured during 
the travel of the railway vehicle and from the torsional angle on the 
respective truck, as well as from the known distance between the center 
pivot and the respective virtual center point of the truck in question, 
and stored. This same measurement procedure is repeated for the respective 
subsequent differential track segment, and the resulting coordinates for 
this partial track segment are again stored. This measurement and storage 
of measurements takes place at least over a distance that lies between the 
first and the last truck of the multiple-unit railway vehicle. In the 
track segment thus simulated, therefore not only is the point at which the 
first truck is located determined, but also the points at which the one or 
more following trucks are located. Once the curvature of the track segment 
at these additional points is contained in the storage sequence, the 
current actual position for all the current contact points of the trucks 
is known, after the trucks have entered the track segment in question. 
To find the actual position of the trucks, the set point position of the 
car bodies must be determined as it occurs under static conditions, when 
the railway vehicle is at this point. In the static set point position, 
the clearance is minimized. In this static set point position, moreover, 
the energy stored in the secondary springs as a result of the torsion and 
transverse displacement of the car body with respect to the truck is at 
its minimum. The set point position of the car bodies in relation to one 
another can thus be determined on the basis of the minimum energy stored 
in the secondary spring elements and can be output as a set point angle 
for the position of the center pivot and the truck with respect to the car 
bodies as corresponding set point signals. The set point position and the 
corresponding set point signals are then compared to the actual position 
or the actual value signals for the articulation angle and the torsional 
angle, and on the basis of this comparison, a system of actuators is 
controlled which counteracts any difference between the set points and the 
actual values. Therefore the actual values of the articulation and 
torsional angles are first evaluated for a determination of the curvature 
of the track, from that value the static set point position of the car 
bodies is determined in relation to the current track segment, compared to 
the actual values previously determined, and on the basis of that 
comparison, a control signal for the system of actuators is generated to 
bring about a correction of the difference between the set points and the 
actual values. 
If active force-dispensing actuator elements are used during this process, 
when the actual value lags behind the set point, a force component can be 
exerted on the car bodies in the vicinity of the center pivot or between 
the car bodies and the corresponding truck that accelerates the car bodies 
toward the set point position, and if the actual value exceeds the set 
point value, these actuators can also exert a force in the opposite 
direction. On the other hand, if controllable dampers are used, then these 
dampers can be used in the event of a change in the actual position that 
moves away from the set point position to counteract any further change of 
the actual position in the same direction. The damper elements are 
accordingly active only as long as the actual value is moving away from 
the set point after the set point has been reached. Changes of the current 
actual value toward the set point, on the other hand, are not damped. 
The control system claimed by the invention is advantageous in particular 
if the car bodies are pushed into an unusual and/or hazardous V or Z 
position with respect to one another and are in danger of jumping the 
track as a result of brake failure, failure of the drive unit on a leading 
truck or similar malfunctions. 
To determine the curvature of the track, the difference between the 
distances traveled by the track wheel of the first truck on the inside of 
the curve and the track wheel on the outside of the curve can be measured, 
and that value can be used to determine the radius of curvature of the 
track in the vicinity of the first truck in the direction of travel. The 
values determined in this manner are in turn stored in the form of a 
measurement sequence at least for the current segment of track between the 
first and last truck, in particular in the form of measurements plotted on 
a system of coordinates, so that the data or measurement sequence stored 
simulates the current curvature of the track that is being referenced for 
the determination of the set point position of the car bodies. The 
difference between the distances traveled can be determined from the 
different speed of rotation of the track wheels on the inside and the 
outside of the curve, by optical odometers or odometers that use radar or 
ultrasound. It is also possible, however, to evaluate the transverse 
displacement, the inclination and the speed of travel of the first car 
body to determine the curvature of the track and to store the radius 
values for differential track segments in a sequence for a simulation of 
the track segments over which the train is currently traveling. 
For the technical processing, a current value signal that is a function of 
the angular position is generated for the articulation angle that results 
from the current position of the car bodies and for the torsional angle 
between the car body and the truck. Separate electrical set point signals 
are generated corresponding to the set point position of the car bodies 
calculated from the simulation of the current track, for the resulting set 
point values of the articulation angle and the torsional angle. These 
current value and set point value signals are compared, preferably 
electrically or digitally, and from the result a control signal is derived 
that controls the system of actuators that are operated to assist in 
bringing the current actual value signal closer to the corresponding set 
point signal, or to counteract an overshoot or undershoot. If a system of 
actuators with a damper characteristic is used, the system of actuators is 
regulated so that only changes of the actual value that are moving away 
from the set point are damped. The damping action can thereby be regulated 
as a function of the gradient of the change, so that the damping value is 
high at high rates of change. The system of actuators can thereby have 
actuator elements that are located at least in the vicinity of the center 
pivot, between the two neighboring car bodies and/or also between the 
truck and the corresponding car bodies. Preferably, the system of 
actuators is laid out symmetrically with respect to both the center pivot 
and the respective truck. 
If the multiple-unit railway vehicle consists of two cars that are 
connected by means of a center pivot, in which the two pairs of cars are 
connected by means of a drag link that pivots on both ends and is located 
between the second and third cars, then in this case it is appropriate if 
the curvature of the track over the entire length of the railway vehicle 
is also stored and the set point position is determined separately for 
each pair of cars, whereby the basis for this determination is also the 
minimum of the energy of the respective pair of cars stored in the 
secondary spring elements. 
The invention is explained in greater detail below with reference to the 
accompanying schematic drawings of one embodiment, in which:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
On a railway vehicle, there are three car bodies 1, 2, 3, each of which 
sits on only one two-axle truck 4, each by means of two elastic secondary 
spring elements 5 which, for their part, are located on a line that is 
oriented at right angles to the longitudinal axis of the respective car 
body, and which, in addition to their vertical spring characteristic, also 
permit a twisting around a vertical axis and a transverse displacement. 
The respective car bodies 1, 2, 3 can thereby be twisted in a plane that 
lies parallel to the corresponding truck 4 to a limited extent and can be 
displaced laterally. A displacement of the truck 4 in the longitudinal 
direction of the car body is thereby prevented by at least one drag link 
that can pivot in the longitudinal direction on the truck 4 and on the car 
bodies 1, 2 3, which drag link transmits the traction forces between the 
truck 4 and the car bodies 1, 2, 3 that occur in the longitudinal 
direction of the car bodies. The secondary springs 5 thus make possible a 
twisting of the longitudinal axis of the truck with respect to the 
longitudinal axis of the corresponding car body by the angle a, and are 
generally of different sizes on the individual cars. To measure this angle 
a, there are respective torsional angle sensors 6 which are connected on 
one hand to the corresponding car bodies 1, 2, 3 and on the other hand to 
the corresponding truck 4. 
The torsional angle sensors 6 generate torsional angle actual value signals 
V1, V2, V3 as a function of the respective torsional angle a, which actual 
value signals are transmitted and used as the input signals of a control 
unit 7. The car bodies 1, 2 and 2, 3 respectively are pivotably connected 
by means of a center pivot 8 with a corresponding articulation angle 
sensor 9, whereby the center pivot 8 is the only coupling between the 
neighboring car bodies. The articulation angle sensor 9 generates an 
actual value articulation angle signal K1 or K2 as a function of the 
articulation angle between the longitudinal axes of the corresponding car 
bodies, which actual value signals are transmitted and used as the input 
signals for the control unit 7. 
To influence the articulation angle on the individual center pivots 8, 
there is a system of actuators with controllable actuator elements 10 laid 
out symmetrically with respect to the respective center pivot 8 between 
the facing ends of the neighboring car bodies, by means of which actuator 
elements a force component can be generated between the neighboring car 
bodies. Additional corresponding actuator elements 11 are located in a 
symmetrical arrangement and are effectively connected on one hand to the 
respective truck 4 and on the other hand to the corresponding car bodies 
1, 2 and 3 respectively. Each actuator element 10 is equipped with an 
actuator control input AST which is connected to the respective actuator 
control outputs AST 1 to AST 4 on the control unit 7. The actuator 
elements 11 also have control inputs S which, for their part, are 
connected to corresponding control outputs S1 to S6 of the control unit 7. 
The control inputs for the actuators 11 of a truck 4 can thereby be 
connected in parallel, to prevent an asymmetrical twisting of the truck 
under the action of these actuators 11. 
The wheels 12 of the two wheel sets of each truck 4 run on the tracks 13 so 
that the corresponding truck is forced to assume a position defined by the 
section of track over which it is currently traveling. This position 
corresponds essentially to the tangent to the curved track segment 13 in 
the vicinity of the respective truck 4. As a result of the fact that the 
car bodies 1, 2, 3 are coupled only at the respective center pivot 8, 
these car bodies cannot be freely oriented as a function of the position 
of the truck. Consequently, there is a twisting of the secondary springs 5 
around a vertical axis, and as a rule also a slight displacement at a 
right angle to the longitudinal axes of w1. The angular position of the 
individual car bodies 1, 2, 3 with respect to the longitudinal axis d1 of 
the corresponding trucks 4 is shown in FIG. 2. FIG. 2 also shows, although 
on a greatly enlarged scale, the transverse displacement h that occurs 
with the twisting between the longitudinal axis of the car bodies w1 and 
the longitudinal axis of the truck d1, which is also generally of 
different magnitudes on the individual car bodies 1, 2, 3. This twisting 
and transverse displacement must be absorbed by the respective pairs of 
secondary springs 5, i.e. the secondary springs 5 store the energy that 
results from these movements. Under static conditions, i.e. when the 
railway vehicle is stationary, the sum of these individual energies 
assumes a minimum value. When the train is in motion, this energy 
increases as a result of the additional dynamic forces involved. 
Accordingly, the clearance required by the entire railway vehicle during 
static operation is a minimum, and when the train is in motion the 
clearance reaches values that can exceed the clearance corresponding to 
static operation. To counteract this phenomenon, the vehicles are 
controlled so that under dynamic conditions, i.e. when the train is in 
motion, and as a function of the segment of track over which the cars are 
currently traveling, the car bodies 1, 2, 3 are placed in a position that 
corresponds to the static conditions by means of the actuators 10 and 
possibly also 11. As part of this process, the curvature of the track is 
measured and simulated at least over a length that lies between the first 
and last trucks of the railway vehicle running on the track segment 13. 
For this track segment, which is continuously updated as the train 
continues to move, the set point position of the car bodies with respect 
to one another is determined which, as explained above, is the position 
they would assume with respect to one another under static conditions, 
i.e. in stationary operation, with respect to the track, taking into 
consideration the contact points of the trucks with respect to one 
another. By a comparison of the current actual position of the car bodies 
with respect to one another with the corresponding set point position 
determined from the curvature of the track segment, the difference is 
counteracted as a function of the result of the comparison, at least if 
the actual value is moving away from the set point value. This procedure 
is appropriate if the actuators used for the mechanical control are 
controllable dampers that reduce mobility in the vicinity of the center 
pivot and/or between the respective truck and car body. In this case, 
hydraulic dampers in particular are used, the damping characteristic of 
which is dependent on the speed of adjustment. If force-dispensing 
actuators such as hydraulic cylinders or motor-driven spindle drives are 
used, then controlled force components can be introduced between the car 
bodies or between the truck and the corresponding car body which actively 
move the articulation angle and/or the torsional angle toward the set 
point, and if the actual value is greater than the respective specified 
set point value, also counteract this change by changing the direction of 
force. 
The curvature of the segment of track over which the cars are currently 
traveling can be determined in a number of different ways. For example, it 
is possible at a constant cadence, i.e. in a plurality of steps, to 
continuously determine the current articulation angle between the 
longitudinal axes of two neighboring car bodies and the torsional angle at 
least between the first truck in the direction of travel and the 
corresponding car body, and from these angles and the specified distances 
between the center pivot and the two neighboring trucks, to determine the 
radius of curvature of the segment of track in the vicinity of the first 
truck for the current differential track segment at that point. A 
differential track segment is thereby a short section of track, compared 
to the length of the segment between the first and last trucks. For this 
differential track segment, measurements plotted on a system of 
coordinates are also taken, and these measurements are continuously stored 
at least for the segment of track that lies between the first and last 
trucks as a simulation of the corresponding track segment. The values for 
track segments that lie behind the last truck in the direction of travel 
can each be deleted if the track segment as a whole is no longer to be 
traveled over by additional trains which do not have their own line 
profile measurement systems. 
The curvature and profile of the track, however, can also be determined 
from the difference between the distances traveled by the wheels on the 
rail on the inside of the curve and the rail on the outside of the curve, 
whereby this difference is used to determine the radius of curvature of 
the track in the vicinity of the first truck in the direction of travel, 
and the measurements plotted on a system of coordinates are thereby 
derived for the corresponding differential segments and can be stored as a 
digital simulation of the distance traveled in the form of a series of 
measurements. The difference in the distances traveled can thereby be 
determined by a measurement of the number of rotations on the idler wheel 
of the first truck on the inside and the outside of the curve, or by 
ultrasound or radar distance measurement devices. The curvature and 
profile of the track, however, can also be determined from the transverse 
acceleration, the inclination of the car body and the speed of travel, by 
determining the radius of curvature of the track from these values and for 
corresponding differential track segments, again storing the measurements 
plotted on a system of coordinates as the curve profile in a multi-cell 
memory. 
For the determination of the current set point position of the car bodies 
1, 2, 3 with respect to the current profile of the track 13 stored in the 
memory, the initial assumption is that in the static idle position 
corresponding to the set point position, the secondary springs 5 of the 
car bodies connected to one another by center pivots 8 are at an overall 
energy minimum with respect to their twisting around a vertical axis and a 
transverse displacement. Accordingly, in a digital calculation based on an 
algorithm corresponding to the current curvature of the track segment, 
preferably a determination is made of the angles at which neighboring car 
bodies must be with respect to one another in the set point position, or 
their trucks with respect to the car bodies. Therefore, the set point 
signals for the articulation angle between the longitudinal axes of the 
neighboring car bodies corresponding to the set point position are 
determined. Analogously, for the determined set point position, the 
corresponding set point signals are also generated for the torsional angle 
between the truck and the corresponding car body by digital data 
processing. 
The actual position of the car bodies results from the articulation angle 
and the torsional angle(s), as they are actually measured by the 
articulation angle sensor 9 and the torsional angle sensor 6, and as they 
are output, in particular in the form of electrical actual value signals K 
and V respectively, and transmitted to the control unit 7 for further 
processing. 
In the control unit 7, the actual value signals are compared to the set 
point signals, and the actuators 10 and possibly 11 are controlled as a 
function of this comparison. The actuators 10, 11 can thereby be 
controlled so that for actual value signals that lag the set point values, 
which result from the articulation or torsion forces between the 
corresponding car bodies or between the truck and the car body and caused 
by the dynamics, are supported so that the actual value signals approach 
the set point signals or so that, if the actual values exceed the set 
point value, the actuators are controlled in the opposite direction. On 
the other hand, if the actuators are realized in the form of only damping 
elements, an active support of the rotational movements for a more rapid 
approximation of the actual values to the set point values is not 
possible, but if the actual value has reached the set point value and then 
continues to move away from the set point, there is a damping of the 
corresponding car body movement. As soon as the actual value then again 
comes closer to the set point value, this damping is neutralized, so that 
the car body actual position can come as close as possible to the set 
point position without any hindrances. 
Each actuator system 10, 11 preferably has actuator elements that are 
oriented symmetrically in twos with respect to the corresponding center 
pivot 9 and/or to the trucks 4. While the actuators 11 on the truck 4 must 
each work in the same direction to achieve a symmetrical twisting with 
respect to the corresponding car body, and therefore for each truck 4 can 
be connected to a common output S1/S2, S3/S4, S5/S6 of the control unit 7, 
the actuator elements 10 in the vicinity of the respective center pivot 9, 
on account of their location in a horizontal plane next to the center 
pivot 9 must be controlled in the opposite direction. Therefore when one 
of the one actuator elements 10 is extended, the other must be either idle 
or must be controlled in the sense of shortening the axial length. 
FIG. 3 illustrates the "static" articulation angle set point value in 
comparison to the corresponding "dynamic" articulation angle actual value, 
and simultaneously the "static" torsional angle set point value in 
comparison to the "dynamic" torsional angle actual value on the first 
truck in the direction of travel for a segment of track that leads from a 
straight section into a curve with a constant radius of curvature. The set 
point and actual value signals have thereby had the parasitic oscillations 
that occur during operation eliminated. Over the length of a section of 
track plotted on the abscissa, articulation angle values are plotted on 
the left ordinate, and torsional angle values are plotted on the right 
ordinate. The 0-points are thereby not at the same level. 
When the first truck enters a curved section of track with a constant 
radius from a straight section of track, the set point of the articulation 
angle increases in an approximately linear fashion to a maximum until the 
two corresponding car bodies or their trucks are running in the curved 
segment. When there is no change in the radius, the articulation angle 
then remains constant at the maximum. The curve of the articulation angle 
set point therefore corresponds to the curve as it is measured 
point-for-point at a speed of travel approaching zero or in stationary 
operation. In the same manner, the torsional angle set point which is 
plotted in the diagram initially decreases, starting from the value zero, 
in the opposite direction, and then rises back to the value zero when the 
second truck has also entered the curve. The car bodies at that point are 
at least largely tangential to the curved rail. 
The curve of the line of the articulation angle set points is calculated 
from the curve of the track over which the train is currently traveling on 
the basis of the smallest of the total energy content of the transverse 
and torsional forces of the corresponding secondary spring elements to be 
taken into consideration, and can preferably be stored as a progressive 
sequence of set points for the corresponding differential track segments. 
The set point for the torsional angle is determined in an analogous 
manner. 
The articulation angle actual value that is assumed when the train travels 
over the track segment in question without the influence of the actuators 
begins of course at the value zero when the train enters a curved section 
of track from a straight line, and as a result of its mass inertia 
increases with respect to the set point with some delay. The mass inertia, 
however, then prevents the termination of the increase in the articulation 
angle actual value when the actual value equals the set point, and thus 
results in the actual value overshooting the set point, as illustrated 
schematically by the line that rises above the set point. 
Unless the articulation of the longitudinal axes of the car bodies are 
assisted by actuator elements that actively apply a force to bring them 
closer to the set point even before the maximum value is reached, when 
actuators with a damping characteristic are used, the overshooting of the 
articulation angle is only counteracted when the actual value exceeds the 
set point. If necessary, the damping action can also be initiated when the 
actual value is only a short distance away from reaching the set point. 
The damping of the increase in the articulation angle after the actual 
value has exceeded the set point is illustrated by the shaded area 
pointing upward in the overshooting curve, whereby the damping action is 
continued only as long as the actual value is moving away from the set 
point. By a correspondingly strong damping, the level of the overshooting 
curve is significantly reduced, ideally to the value zero. The descending 
branch of the overshooting curve is not damped, to avoid delaying the 
approximation to the set point value. When the actual value falls below 
the set point, as illustrated by the curve that drops below the set point, 
there is also a damping of the articulation angle reduction after it 
reaches the set point, to also reduce this undershoot to a minimum. The 
curve segment that then runs toward the set point is in turn not damped. A 
damping of differences between the set point and current value is thereby 
performed only when it exceeds certain specified limit values, so that 
small, normal operational angular differences are tolerated. 
The curve of the actual value of the torsional angle under dynamic 
operating conditions illustrated by the dotted line initially follows, at 
an increased amplitude, the curve of the torsional angle set point value 
which is also calculated from the track geometry, so that after returning 
to the value zero, it can also oscillate beyond the value zero as a result 
of the mass inertia of the car bodies. To the extent that this 
overshooting cannot already be limited to harmless levels by means of the 
actuators in the vicinity of the center pivot, the actuator elements 11 
are used, which act between the truck 4 and the corresponding car bodies 
1, 2 or 3. It thereby becomes possible, by means of actuator elements 11 
that apply active force, e.g. hydraulic cylinders or electric actuators, 
to counteract the negative rebound beyond the set point. If only damping 
elements are used as actuators, it is only possible to counteract the 
overshooting or undershooting of the set point by the corresponding 
control of the actuators. In this case, too, a damping corresponding to 
the shaded field is continued only as long as the actual value, after 
reaching the set point, moves away from the set point in a positive or 
negative direction. Movements of the truck with respect to the car body 
that approach the set point, however, are not damped. Here again, it is 
possible to initiate the damping shortly before reaching the set point, to 
reduce the overshoot to a minimum. 
Corresponding control methods can also be carried out using the actuators 
if the railway vehicle leaves the curved section of track, and 
corresponding oscillation processes become active, in the opposite 
direction, in the straight section of track. 
When the car bodies are controlled by influencing the articulation angle 
between the longitudinal axes of the car bodies, possibly with assistance 
by the system used to control the position of the trucks with respect to 
the car bodies, the positions of the car bodies with respect to one 
another can be controlled so that an orientation of the car bodies with 
respect to one another under dynamic conditions is achieved that is at 
least approximately the same as under static operating conditions, so that 
the railway vehicle overall has a clearance requirement that approaches 
the actual track curvature and in particular remains within this clearance 
requirement if malfunctions in the braking and/or drive elements or other 
factors could lead to thrust or shearing forces that could cause the 
coupling to buckle.