Note: Descriptions are shown in the official language in which they were submitted.
CA 02284204 2001-10-26
21421-300
Rail vehicle with an articulated joint
The invention concerns a rail vehicle comprising
two or more wagon bodies each pair of wagon bodies being
interconnected through a single-axle articulated joint which
can pivot angularly about a vertical axis, each wagon body
being supported through resilient spring elements on a
mufti-axle bogie located in the region of the centreline of
the wagon body. Control means are provided for recording
the pivoting angles between the bogies and the wagon bodies
as well as the articulated angle at the articulated point,
and controllable servo elements are provided for influencing
the angle of articulation.
In the case of known rail vehicle of this type
(DE-A 2060231) two wagon bodies are joined with each other
via a single-axle articulated joint. In this case the wagon
bodies are supported on a mufti-axle bogie provided
approximately in the centre of the wagon body. The bogies
can pivot relative to the associated wagon bodies about a
vertical axis. At both sides of the articulated joint the
wagon bodies are joined with each other by means of
controllable elements. At the same time the control of the
servo elements is carried out as a function of
potentiometers as control means, which register the pivoting
angle between the respective bogie and the associated wagon
body as well as the angle of articulation of the articulated
joint. The control of the servo elements is carried out in
such a manner that the pivoting angles are equal. In this
construction it becomes apparent that for the purpose of
generating an adequate adjusting force the servo elements,
due to the short usable lever arms and the large masses to
be moved, have to have a very strong construction.
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In addition, the mechanical coupling positions have to be
correspondingly dimensioned to suit the great forces
occurring and due to the mass moment of inertia the
adjustment of the pivoting angle is very much delayed.
A further known rail vehicle (DE-A 2854776) is
constructed particularly as an articulated tram and
comprises two wagon bodies, each of them being supported by
a twin-axle~bogie arranged approximately along the
longitudinal centre of the wagon. The ends of the two wagon
bodies which face each other, are couples by means of an
articulated joint, the single pivoting axle of which extends
vertically. At the same time the pivoting angle between the
respective bogie and the associated wagon body is determined
by means of a control mechanism with a coupled distance
sensor and the angle of articulation is determined by means
of at least one distance sensor assigned to the articulated
joint. The signals generated by the distance sensor are
introduced to a control unit, which controls a servo unit
allocated asymmetrically, or two servo elements allocated
symmetrically, to the articulated joint. On this occasion
the angle of articulation of the articulated joint is so
influenced, that the twin-axle bogie, without a trunnion, on
which the wagon bodies are supported via resilient secondary
springs, are completely relieved from exercising the
function of the force dispenser. In this case, while
travelling on a straight section, the servo element blocks
the articulated joint in a position over the centre of the
track and when travelling in a curve it forces the buckling
of the articulated joint to the outside of the curve of the
track, thus improving the use of the clearance when the rail
vehicle travels on a curve.
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The object of the invention is to specify a rail
vehicle of the generic type and a method to control same, by
which the wagon bodies are controlled during a dynamic
travel in a position relative each other with an improved
force introduction, which position corresponds to the static
position in the actual section of the track.
The invention provides a rail vehicle comprising:
two wagon bodies which are joined by means of a single-axle
articulated joint which can pivot through an axle about a
vertical axis, each wagon body supported via resilient
spring elements on a multi-axle bogie provided in the region
of the longitudinal centreline of the wagon body; and
control means for the purpose of recording a pivoting angle
between a wagon body and the associated bogie, as well as an
angle of articulation (K) on the articulated joint; and
controllable servo elements for the purpose of influencing
said angle of articulation (K) which is controlled as a
function of the control means in accordance with the
relationship
Knoll = Kist + A2ist - Alist
where -
Knoll = a desired value of the angle of articulation,
Kist = the recorded actual value of the angle of
articulation,
Alist = the recorded actual pivoting angle between the
preceding, in the direction of travel, bogie and the
associated wagon body, and
A2ist = the recorded actual pivoting angle between the
following, in the direction of travel bogie and the
associated wagon body,
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CA 02284204 2001-10-26
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characterised in that further controllable servo elements
are provided on the articulated joint at least between one
of the wagon bodies and the associated bogie and that said
servo elements are controllable damping elements.
In the case of a refinement of a rail vehicle
according to the invention on the one hand the actual angle
of articulation of the articulated joint and on the other
the pivoting angles, between the bogies and the respective
associated wagon bodies are determined. The actual values
of these angles are added taking their signs into
consideration, whereby the pivoting angle between the first
bogie, viewed in the direction of travel, and the associated
wagon body, is subtracted. The sum of this addition is the
measure of the desired angle of articulation which the joint
should assume under actual operating conditions. Provided
according to this, for example, on a straight section of the
track the sum of the actual pivoting angle deviates from the
actual angle of articulation, the deviation of the
articulation joint will be counteracted by means of
mechanical servo elements. These servo elements may be
provided between the bogie and the associated wagon body and
influence forcibly the angle of articulation of the
articulated joint by changing the actual value of the
pivoting angle. In a preferred manner servo elements are
allocated to both the articulated joint and the bogies/wagon
bodies. In particular in the case of servo elements one can
deal with controlled damping elements which act against a
change of the pivoting angle until the externally acting
force cause a change in the actual value which exceeds the
desired value. If, in contrast, it is established that the
actual value moves toward the desired value, the damping
effect of the damping element is cancelled.
-2b-
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Should the actual value move towards the desired value too
fast and an overshooting is expected, the change of the
actual value is slowed down by engaging the damping effect
shortly before reaching the desired value. If the deviation
between desired/actual remains constant or increases in an
unchanged manner notwitstanding the counteracting damping
elements, a traction instruction has to be issued either to
a central control unit or to the driver of the rail vehicle,
according to
-2c-
CA 02284204 1999-09-17
which in the case of, for example, a too strong a deflection
the following bogie is braked or the preceding wagon is
accelerated.
Furthermore, in the case of the servo elements one can deal
with active servo elements which not only act against changes
when the actual value is drifting away from the desired value,
but in the absence of external restoring forces also affect the
return of the actual value to the desired value.
When measuring the pivoting angle and the angle of articulation
the significance of a sign definition is established, whereby,
for example, one will always commence from the value of zero
when the longitudinal axes of the respective bogie is parallel
to the longitudinal axis of the associated wagon body and the
longitudinal axes o.f the wagon bodies are aligned with each
other. The pivoting angles are considered positive when the
longitudinal axis of the wagon body is pivoted clockwise
relative to the longitudinal axis of the associated bogie. The
pivoting angles are considered negative when the longitudinal
axis of the wagon body is pivoted anti-clockwise relative to
the longitudinal axis of the associated bogie. Negative values
of the angle of articulation occur when the preceding wagon
body deflects anti-clockwise relative to the following wagon
body. Positive values of the angle of articulation occur when
the longitudinal axis of the first wagon body deflects
clockwise relative to the longitudinal axis of the second wagon
body.
A two-element rail vehicle with an articulated joint with a
vertical pivoting axis between the two wagon bodies and with
resilient restoring elements between the wagon bodies and the
respective bogie requires the smallest clearance in the static
stationary state. It has been ascertained for this state that
when the train is at standstill on any real rail track, the
pivoting angles are approximately the same. In the case of a
rail vehicle fitted in this manner the control of the pivoting
angle can be so carried out that first the actual pivoting
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CA 02284204 1999-09-17
angles between the bogies and the associated wagon bodies as
well as the actual angle of articulation on the articulated
joint are measured repeatedly by taking into consideration the
positive or negative signs of the angles at least during the
travelling. By adding up these angular values an adjusting
signal is generated in the control unit, which signal
corresponds to the desired value of the angle of articulation
and controls the mechanical force components acting against the
deviation of the angle of articulation if there is a deviation
from the actual angle of articulation measured on the
articulation joint. These force components act directly on the
articulated joint. Deviations from the ideal angle of
articulation, corresponding to the minimum clearance
requirement, may arise during operation due to various traction
forces on the bogies, in case of unequally Working brakes,
faulty rails, the spinning of one of the drive wheels, when
entering into a curve from a straight section as a result of
the acting dynamic force of inertia, in thrust operation or the
like.
If two or more similarly controlled two-element trains are
joined by means of a coupling rod each, wherein each coupling
rod is joined via a joint to the second wagon of the preceding
train and to the first wagon of the following train, then all
coupled trains are operated according to the same control
principle.
It could be of further use to influence at least one of the
pivoting angles by means of servo elements for the purpose of
minimising the required clearance. At the same time the
pivoting angle is controlled towards a desired value,
corresponding to the arithmetic average value of the two
pivoting angles actually measured during dynamic operation.
The invention is explained in detail based on basic sketches of
an embodiment. They show in:
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CA 02284204 1999-09-17
Fig.i - a two-element rail vehicle with adjusting and control
means for the determination of the angles as well as
for counteracting,
Fig.2 - the rail vehicle on a straight section with the
longitudinal axes of the wagon bodies being buckled
relative to each other,
Fig.3 - the rail vehicle on a curved rail track.
In the case of a rail vehicle two wagon bodies 1, 2 are
provided, each of which being mounted only on a twin-axle bogie
4, without a trunnion, via two resilient secondary spring
elements 5, the bogies arranged approximately along the
longitudinal centreline of the wagon bodies. The secondary
spring elements 5 in turn are arranged on a line extending
transversely to the longitudinal axis of the respective wagon
body. In addition to their vertical spring properties, the
secondary springs 5 allow an additional rotation about a
virtual vertical axis and a limited transverse movement. By
virtue of this the respective wagon body 1, 2 can carry out a
limited rotation in a plane which is parallel to the associated
bogie 4 as well as it can carry out a lateral movement. At the
same time a movement of the bogie 4 is prevented in the
longitudinal direction of the wagon body by virtue of at least
one connecting rod, which extends in the longitudinal direction
and is joined in a pivoting manner to the bogie 4 and the wagon
body 1,2, the connecting rod transferring the traction forces
between the bogie 4 and the wagon bodies 1 and 2 which occurs
in the longitudinal direction of the wagons. Thus the secondary
springs 5 make a pivoting of the longitudinal axis of the bogie
relative to the longitudinal axis of the associated wagon body
feasible by an angle of AZ and A2, respectively, which, as a
rule, may be different for the individual wagons during the
operation. For the determination of this angle A a pivoting
angle sensor 6 each is provided, which is coupled to the
associated wagon body 1, 2 on the one hand and to the
associated bogie 4 on the other. Depending from the respective
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CA 02284204 1999-09-17
pivoting angle A, the pivoting angle sensors 6 generate the
actual pivoting angle signals V1, V2, which are fed as input
signals to a control unit 7.
When the longitudinal axes of the bogie 4 and the associated
wagon body 1, 2 are aligned, the pivoting angle sensors 6
generate a value corresponding to 0° of the pivoting angle A.
When the wagon body pivots clockwise relative to the bogie, a
signal corresponding to a positive pivoting angle is generated:
when the wagon body pivots anti-clockwise relative to the
associated bogie, then a signal for a corresponding negative
angular value is emitted. The wagon bodies 1, 2 are joined to
each other by means of a single articulated joint 8, which has
a vertical joining axis. An angle of articulation sensor 9 is
assigned to the articulated joint, which sensor in the case of
the longitudinal axes of the wagon bodies l, 2 lying in one
line generates an angle of articulation signal corresponding to
an angle of articulation equalling 0°. When the longitudinal
axis of the wagon body 2 pivots anti-clockwise relative to the
longitudinal axis of the wagon body l, the generated angle of
articulation signal corresponds to a positive angle of
articulation. When, in contrast, the longitudinal axis of the
second wagon body pivots clockwise relative to the longitudinal
axis of the wagon body 1, the generated angle of articulation
signal corresponds to a negative angle of articulation. The
actual signal values K, generated by the angle of articulation
sensor 9, are also fed to the control unit 7 as input signals.
The desired value of the angle of articulation R is determined
in the control unit 7 by carrying out an addition of the actual
pivoting angles A1 and A2 as well as of the angle of
articulation K according to the equation
Ksom v Kte~ 'f A2 - A1
while observing the positive and negative signs of the measured
angles. The result of this addition is converted into a control
signal, which acts on the articulated joint 8 via servo
elements producing mechanical forces. For the purpose of
6
CA 02284204 1999-09-17
influencing the angle of articulation K, as servo elements
controllable hydraulic actor elements 10 are provided
symmetrically about the articulated joint 8 between those ends
of the adjacent wagon bodies l, 2 which face each other, with
the aid of which servo elements a force component can be
produced between the adjacent wagon bodies 1, 2, this component
causing an operationally warranted increase or decrease of the
angle of articulation R,st in accordance with the associated
control signal. When, in addition to the angle of articulation
R, at least one of the pivoting angles A1 and/or A2 is
controlled, then the arithmetic average value is formed from
the two actually measured dynamic pivoting angle values and by
means of associated actors 11 the, or both, pivoting angles)
is (are) controlled on the respective bogie/wagon body by
observing the relevant chosen sign definition from this average
value. On this occasion it is assumed that the two pivoting
angles A1 and A2 are approximately equal when the minimum
clearance is required. Each force component produced by the
actors 11 acts against the deviation. These actor elements li
are effectively connected symmetrically to the respective bogie
4 on the one hand and to the associated wagon bodies 1, 2 on
the other, thus enabling them to carry out a pivoting relative
each other in accordance with the required angle of
articulation. On this occasion the provision of one actor on
one bogie only may suf f ice .
Each actor element to is equipped with an actor control input
~I.ST, which are connected to the corresponding actor control
outputs ~I.STl and AST2 of the control unit 7. The actor elements
11 too have control inputs S, which, in turn, are connected to
the corresponding control outputs S1 to S4 of the control unit
7. At the same time the control inputs for the actors 11 of a
bogie may be connected parallel to prevent an asymmetrical
pivoting of the bogie brought about by these actors 11.
The wheels of both sets of wheels of each bogie 4 run in the
gauge of a track 13, so that the associated bogie inevitably
assumes a position determined by the rail section being
7
CA 02284204 1999-09-17
travelled on. This position corresponds essentially to the
tangent to the rail section 13 in the region of the respective
bogie 4. By virtue of the wagon bodies 1, 2 coupled by the
articulated joint 8, in a dynamic travel mode they cannot align
freely to correspond with the position of the bogie. Therefore
a twisting of the secondary springs 5 about a virtual vertical
axis takes place and, as a rule, also a slight transverse
movement relative to the longitudinal axes WRL1 and WRL2 of the
wagons. This twisting and transverse movement has to be taken
up by the respective pairs of secondary springs 5, i.e. the
secondary springs 5 store the energy arising from this. in the
static state, i.e. when the rail vehicle is stationary and not
being braked, the sum of these individual energies is at a
minimum. In the travel mode this energy changes due to the
additionally acting dynamic forces. Accordingly, in static
operation the clearance required for the entire rail vehicle is
at a minimum and during travel it reaches values which may
exceed the clearance required in the static operation. To
enable to counteract this, the control is so carried out that
during the dynamic travel the wagon bodies 1, 2 are controlled
by means of the actors 10, and possibly 11, into a position
corresponding to that of the static state as a function of the
actually measured values of the pivoting angle A and of the
angle of articulation K.
In the case of a configuration according to Fig.2 a two-element
rail vehicle is situated on a straight section of the track 13.
On this occasion wagon 2 is in the thrust mode, so that the
articulated joint 8 and, consequently, the longitudinal axes
WKL1 and WRL2 of the wagon bodies are laterally deflected
relative to the longitudinal axes DGL1 and DGL2 of the bogies,
which axes are in alignment with the section of the track 13.
The pivoting angle sensor 6 on the preceding wagon 1,4 in this
case registers a positive pivoting angle A1, whereas the
pivoting angle sensor 6 on the second wagon 2,4 registers a
negative pivoting angle A2 of the same magnitude, consequently
the longitudinal axis WKL2 of the wagon is pivoted against the
longitudinal axis WKL1 of the wagon anti-clockwise relative to
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CA 02284204 1999-09-17
the longitudinal axis of the bogie 1~ Therefore the actual
angle of articulation assumes, by definition, a positive value
for the angle of articulation Kist. which according to Fig.1
corresponds to the sum of the absolute values of the pivoting
angles Alist and A2,st~ Thus the angle of articulation Knoll is
zero in accordance with the conditions of the formula.
Therefore the actor, or actors, 10 or 11 have to be so
controlled that the angle of articulation is brought to zero,
consequently the longitudinal axes 1 and 2 of the wagons will
be aligned with the longitudinal axes 1 and 2 of the bogies and
thus in the case of a straight track 13 are parallel to their
longitudinal axes.
If controllable damping elements only are used as actors, then
the actors 10 are switched to high damping values already at
the commencement of the lateral deflection of the articulated
joint 8, thus practically preventing a lateral deviation of the
articulated joint. A restoring of the articulated joint is
carried out during the operation automatically when, for
example, the thrust mode of the wagon 2 finishes or the
preceding wagon pulls or is braked to a lesser extent. The
restoring forces of the secondary springs 5 assist the reverse
pivoting of the longitudinal axes of the wagon bodies into an
alignment with the longitudinal axes of the bogies, whereby
then damping action of the actors 10 can be appropriately fully
cancelled when the actual measured value of the angle of
articulation Rest changes towards the desired value angle of
articulation. In a corresponding manner, by damping the
pivoting movement, the actors 11 between the bogie 4 and the
associated wagon body 1 and/or 2 can counteract a change
drifting away from 'the desired value. When these damping
measures are adequate, the control unit 7 can order
additionally a braking of the second wagon 2,4 or an
acceleration of the first, preceding, wagon 1,4 or control the
bogies by means of 'the driving motors. When actors 10 and/or
11, which actively introduce forces, are used, the force
components necessary to move the actual value of the angle of
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CA 02284204 1999-09-17
articulation to the desired value of the angle of articulation
are actively controlled.
When the first wagon 1,4 pulls on a uniformly curved rail
section 13, there is the danger that the actual value of the
angle of articulation K,st will be too small, so that according
to Fig.3 the free ends of both wagon bodies 1 and 2 pivot
towards the outside the bend and the middle ends of the wagons
with the articulated joint 8 pivot towards the inside of the
bend thus increasing the clearance required. From the
geometrical conditions which, for the purpose of clarification
of the operation are exaggerated as far as the geometrical
relationships are concerned, it becomes obvious that the angle
of articulation R,st is considerably smaller than the desired
value K~11, which is obtained in the point of intersection of
the extended longitudinal axes DGL1 and DGL2 of the bogies.
This desired value of the angle of articulation is obtained by
considering the lines which are parallel to the longitudinal
axes of the bogies according to Fig.3, which pass through the
pivoting joint 8, as the sum of the absolute values of the
angle of articulatian Kist and of the pivoting angles A1 and A2.
Thus the control unit 7 emits in this case control signals to
the actors 10, 11, which will bring an increase of the actually
measured angle of articulation about. Provided the increase of
the actual value of the angle of articulation is carried out
not by deceleration of the preceding wagon 1,4 or acceleration
of the second wagon 2,4, active force components of the actors
10 have to deflect the articulated joint stronger or the actors
11 have to accomplish a reverse pivoting of the wagon bodies
relative to the bogies, or both steps can be controlled
simultaneously. At the same time care has to be taken that
angular values of the magnitude illustrated in Fig.3 cannot
occur in practice, since, as a rule, the pivoting angle A is
small and the radius of curvature of the rail track is
considerably greater than the dimensions of the bogies.
The actual position of the wagon bodies is obtained from the
angle of articulation K and the pivoting angles a, as they are
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CA 02284204 1999-09-17
actually measured by the angle of articulation sensor 9 and the
pivoting angle sensar 6 and emitted, in particular, as
electrical actual value signals K and V and fed to the control
unit 7 for further processing. In the control unit the actual
value signals are compared with the signals of the desired
values of the angle of articulation derived or calculated from
them and, as a result of this a control of the actors 10, and
possibly of 11, is carried out. At the same time the actors 10,
11 can be so controlled, that in the case of actual value
l0 signals lagging behind the desired value, the articulating
and/or pivoting forces between the associated wagon bodies and
bogie emanating from the vehicle's dynamics, are so assisted
that the actual value signals will approach the desired value
signals or that when the actual values exceed the desired value
they will be controlled in the opposite direction. If, in
contrast, the actors are constructed as damping elements only,
an active assistance of the pivoting movements to achieve a
faster catching up of the actual values with the desired values
is not feasible: in this case, however, when the actual value
reaches the desired value and afterwards exceeds the desired
value, a damping of the movement of the corresponding wagon
body is affected. As soon as the actual value starts to
approach again the desired value, this damping is cancelled to
enable the angle of articulation approach the desired angle of
articulation as soon as possible. Should the actual value move
towards the desired value too fast and an overshooting is
expected, the change of the actual value is slowed down by
engaging the damping effect shortly before reaching the desired
value.
The arrangement of the actors 10, 11 has preferably two actor
elements each provided symmetrically about the articulated
joint 9 and/or the bogies 4. While the actors il, positioned
between the bogie 4 and the wagon body 1 and 2, respectively,
have to operate in the same direction for the purpose of
achieving a symmetrical rotation relative to the associated
wagon bodies and therefore for each bogie they can be connected
to a common output .S1/S2, S3/S4 of the control unit 7, the
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CA 02284204 1999-09-17
actor elements 10 in the region of the respective articulated
joint 9 have to be controlled in opposite directions by virtue
of their arrangement in a horizontal plane next to the
articulated joint. accordingly, when extending one actor
element 10, the other has to be either ineffective or be
controlled in the sense of shortening the axial length. When
controlling the wagon bodies by influencing the angle of
articulation between the longitudinal axes of the wagon bodies,
possibly with the aid of controlling the bogies relative to the
to wagon bodies, the position of the wagon bodies relative each
other achieves in the dynamic travel mode an arrangement which
approximates very closely the static operation mode. In this
case, as far as the actual progress on the rail track is
concerned, the rail vehicle requires only an at least
approximate ideal clearance and adheres to this especially when
faulty operations of the brake~and/or drive elements or other
influencing factors may lead to a thrusting mode resulting in
the deflection of the coupling joint or traction forces may let
the angle of articulation become too small when travelling on a
zu curve .
12
