Note: Descriptions are shown in the official language in which they were submitted.
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Drive unit for driving at least one wheel drive shaft, in
particular of a wheelset axle
The invention relates to a drive unit for driving at
least one wheel drive shaft, in particular of a wheelset
axle, for rail vehicles, in particular having the features
from the preamble of claim 1.
Such a drive unit has been disclosed by
DE 4 137 233 A.
The solution described there has, however, the
disadvantage that the necessary installation space is
relatively large, which has disadvantageous effects
particularly in vehicles of the low-platform type. The
fabrication and mounting are also relatively complex.
A similar design of a drive unit has been disclosed
by US 4 042 071 - see column 1, lines 12 - 14 in this
document.
Drive units for rail vehicles, in particular having
an integrated cross-drive, are known in a multiplicity of
embodiments. These comprise a driving engine which is coupled
to a transmission assembly. The drive of the transmission
assembly is formed by a hollow shaft which is coupled via an
articulated coupling to the wheel drive shaft, in particular
the wheelset axle, in order to compensate the relative
movements between the wheelset axle and cross-drive- The
driving engine is arranged here in the direct spatial
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vicinity of the transmission assembly, preferably both -
driving engine and transmission assembly - are connected to
one another by flanges in the region of their housings. As a
result of this measure, only one radial bearing is necessary
for the driving engine and a corresponding end shield. The
coupling of the drive shaft of the driving engine to the
transmission input shaft is carried out by means of what is
referred to as a rotationally rigid and radially rigid
diaphragm coupling. The transmission assembly itself is
usually embodied in two stages or in a single stage with an
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of rotation to the hollow shaft or else forming one physical
unit with said hollow shaft. The assembly composed of the
driving engine and transmission assembly, which is referred
to as an integrated cross-drive, is attached only at three
points in the bogie frame with primary suspension. If
necessary, a braking system is assigned to the drive unit,
the brake disk being arranged on the hollow shaft. The
attachment elements are arranged in the housing of the
transmission assembly. The disadvantage of the previous
solution is that, on the one hand, the overall costs for the
structural implementation and fabrication are relatively
high. Furthermore, in particular for embodiments which are to
be used in low-platform vehicles, the available radial and
axial installation space is considerably reduced as a result
of wheel diameters which are becoming ever smaller while at
the same time drive hollow shaft internal diameters are
becoming larger owing to the softer suspensions. There is
thus no longer sufficient installation space available to
arrange the braking system in this region in order to achieve
sufficient braking deceleration. Solutions for this are to
arrange the braking system at another location or else to do
without conventional mechanical braking systems and use other
braking systems, for example electrical braking systems,
which are however more costly.
The invention has therefore been based on the object
of developing a drive unit for a wheel drive shaft, in
particular a wheelset axle, in particular for the use of rail
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vehicles of the type mentioned at the beginning, in such a
way that sufficient braking deceleration is achieved with
simple means and also with an axial and radial installation
space which is becoming smaller and smaller. The structural
solution is intended here to be defined by a simple
embodiment, cost-effective fabrication and mounting.
Furthermore, the solution according to the invention is to be
applicable in particular for vehicles of the low-platform
type.
The solution according to the invention is
characterized by the features of claim 1. Advantageous
refinements are given in the subclaims.
The drive unit for driving at least one wheel drive
shaft, in particular of a wheelset axle, comprises a
cross-drive with a driving engine and a transmission assembly
which is coupled thereto. The output of the transmission
assembly is embodied as a hollow shaft and is connected to
the wheel drive shaft or the wheelset axle via a coupling, in
particular an articulated coupling. The braking system
comprises two braking subsystems by means of which the
entirety of the braking force necessary can be generated by
activating two braking subsystems.
The solution according to the invention provides the
advantage that as a result of the distribution between a
plurality of braking systems said braking systems can, in
their entirety, be kept respectively smaller in terms of
their dimensions in the radial and axial directions and the
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installation space available can thus be used to an optimum
degree.
There are a multiplicity of ways in which the
individual braking subsystems can be arranged. They can
either be arranged on the two sides of the transmission
assembly, one of the two braking subsystems being arranged
between the transmission assembly and the first coupling
element of the coupling which is necessary for coupling to
the wheelset axle. In order to provide the necessary braking
force while taking into account the necessary installation
space for the individual braking subsystems, additional
attachment means, which take up space, for the elements to be
connected to one another have been dispensed with and the
entire system has been structurally simplified. Here, the
hollow shaft is embodied integrally with at least one of the
attachment flanges for one of the braking subsystems. In a
further advantageous refinement, the first coupling part of
the articulated coupling is also embodied in one piece with
the hollow shaft. As a result, the radial installation space
necessary for the connecting elements is significantly
reduced in comparison with that in embodiments according to
the prior art. The solution according to the invention
provides the advantage that the available radial and axial
installation space resulting from the wheel diameters which
are becoming smaller and smaller while at the same time the
output hollow shaft 'internal diameters are becoming larger
and larger owing to the softer suspensions is utilized to an
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optimum degree and at the same makes available the necessary
braking deceleration.
There are also a multiplicity of possible ways of
arranging the hollow shaft and an attachment flange of a
braking subsystem and/or of the first coupling element of the
articulated coupling in an integrated fashion. Here, the
embodiment can be effected in an integral fashion as a cast
part or forged part. However, the specific selection depends
on the requirements of use and is at the discretion of the
person skilled in the related art.
According to a further aspect of the invention, it is
also possible to arrange both braking subsystems between the
transmission assembly and articulated coupling. In this case,
both attachment flanges form one physical unit with the
hollow shaft.
In one development there is provision for the
transmission housing to be embodied in an integral fashion.
The hollow shaft is supported by means of a bearing
arrangement in the housing of the transmission assembly. For
the sake of simplification and standardization there is
provision for the external diameter of the bearings to be
identical for all embodiment variants, while adjustment is
carried out to the requirements of use by means of variable
bearing arrangement internal diameters and thus hollow shaft
external diameters.
The solution according to the invention is explained
below with reference to figures. They are, in particular as
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follows:
Fig.l shows an axial section of a schematic
simplified view of the basic design of a drive
unit designed according to the invention;
Figs 2a and 2b show the coupling of the attachment flanges of
the individual braking subsystems to the
hollow shaft.
Figure 1 shows a schematic simplified view of the
basic design of a drive unit designed according to the
invention for driving at least one wheel drive shaft which is
coupled to at least one wheel and which is formed by a
wheelset axle 3 in the case illustrated. The drive unit 1
comprises an integrated cross-drive 4. This comprises a
driving engine 5 which is coupled to the transmission
assembly 6. For this purpose, the drive shaft 7 of the
driving engine 5 is connected fixed in terms of rotation to
an input 8 of the transmission assembly 6, preferably via a
coupling element 9 in the form of a diaphragm coupling which
is rotationally rigid and embodied so as to be rigid in the
radial direction. The transmission assembly 6 comprises an
output 10 which is formed by a hollow shaft 11 which encloses
the wheelset axle 3 in the circumferential direction and over
at least part of its axial extent. Said hollow shaft 11 is
connected to the wheelset axle 3 via an articulated coupling
12. The articulated coupling 12 comprises here a first
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coupling part 13 and a second coupling part 14 which can be
connected to one another in a rotationally elastic fashion.
The first coupling part 13 is connected here fixed in terms
of rotation to the hollow shaft 11. The second coupling part
14 is coupled at least indirectly fixed in terms of rotation
to the wheelset axle 3. Here, at least indirectly means that
the connection is made directly to the wheelset axle or else
via further transmission elements, for example a second
coupling level. In one advantageous refinement, the hollow
shaft 11 and the first coupling part 13 are of integral
design. Furthermore, the drive unit 1 comprises a braking
system 15 which is preferably embodied in the form of a disk
brake unit 16.
According to the invention, the braking system 15
comprises at least two braking subsystems 17.1 and 17.2 which
are each embodied as disk brake systems. The necessary
overall braking force is thus generated by two braking
subsystems 17.1 and 17.2. These comprise here a brake disk
18.1 or 18.2 which is only indicated and which can be
attached to the hollow shaft 11. For this purpose, the hollow
shaft has in each case two attachment flanges 19.1 and 19.2
which form one physical unit with the hollow shaft 11, and at
least one flange - the attachment flange arranged between the
transmission assembly 6 and articulated coupling 12 - is
preferably formed with the hollow shaft 11 from one
component. The other 'second attachment flange is attached to
the hollow shaft 11 by means of attachment elements. The two
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attachment flanges 19.1 and 19.2 are arranged here on both
sides of the transmission assembly 6. The activation elements
(not illustrated here) can thus easily be arranged and
attached to the housing 20 of the transmission assembly. The
integral embodiment of the hollow shaft 11 with the
simultaneously integrated attachment flange 19.1 and 19.2 for
the braking subsystems 17.1 and 17.2 and the fact that the
crown gear known from the prior art between the hollow shaft
11 and the first coupling part 13 provides, in addition to
more cost-effective fabrication, the advantage of requiring
less radial installation space. By dispensing with the crown
gear between the hollow shaft 11 and the first coupling part
13, less installation space is required in the radial
direction for the coupling between the hollow shaft 11 and
first coupling part 13. Furthermore, as a result of the
distribution of the braking force between two braking
systems, the available radial and axial installation space
which is becoming smaller and smaller between the hollow
shaft 11 and the wheel diameter while at the same time the
hollow shaft internal diameter D[illegible] is becoming larger
and larger is utilized to an optimum degree.
The driving engine 5 and the transmission assembly 6
are arranged spatially near to one another, preferably
connected to one another by flanges in the region of their
housings 21 and 20. There are also a multiplicity of possible
designs of the transmission assembly 6. In the simplest case
it comprises two pairs of spur wheels, a first set of spur
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wheels 22 and a second set of spur wheels 23. The first set
of spur wheels 22 comprises a spur wheel 24 which is coupled
fixed in terms of rotation to the transmission input shaft 8,
the spur wheel 24 either forming one integral assembly with
the transmission input shaft 8 or else being connected fixed
in terms of rotation to it. The spur wheel 24 intermeshes
with a spur wheel 26 which is arranged on an intermediate
shaft 25. Furthermore, a second spur wheel 27 is arranged on
the intermediate shaft 25, said second spur wheel 27 being a
component of the second set of spur wheels 23 and
intermeshing with a spur wheel 28 which is connected fixed in
terms of rotation to the hollow shaft 11. In one particularly
advantageous embodiment, the hollow shaft 11 and spur wheel
28 are embodied as an integral component. In terms of
fabrication, the integral component composed of the hollow
shaft 11, the attachment flange 19.2 and the first coupling
part 13, and optionally also the spur wheel 28, can be
embodied as a cast part or forged part. As a result, in the
case of minimum external diameter of the articulated coupling
12, here with D12 and of the brake disks, here with D18.1 or
18.2, a simultaneously maximum internal diameter D[illegible] is
possible.
According to a further aspect of the invention, the
housing 20 of the transmission assembly 6 is embodied in an
integral fashion/one piece structure, whereby the bearing
arrangement 29 of the hollow shaft 11 in the housing 20
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provides for a fine gradation of the internal diameter D 129
with simultaneously keeping the roller bearing external
diameter DA29 constant.
The inventive solution of the embodiment of the
hollow shaft 11, attachment flange 19.2 and of the first
coupling part 13 as one integral component can be used for a
multiplicity of integrated cross-drives 4 and is not tied to
a specific embodiment of the transmission assembly 6 or of
the driving engine S. Other embodiments which lie within the
field of activity of a person skilled in the respective art
are also conceivable.
According to figure 2a, the attachment flange 19.2 of
the second braking system 17.2 is embodied in an integral
fashion with the hollow shaft 11. The attachment flange 19.1
of the first braking system 17.1 is connected, as a separate
component, fixed in terms of rotation to the hollow shaft 11
by means of attachment elements 30, for example in the form
of screw elements which are arranged at specific intervals in
the circumferential direction of the attachment flange 19.1.
A structural embodiment of the connection of the brake disk
of the second braking system 17.2 to the attachment flange
19.2 is illustrated in figure 2a. Figure 2b shows a possible
structural embodiment of the connection of the brake disk
18.1 to the attachment flange 19.1 of the first braking
subsystem 17.1, and the attachment of the attachment flange
19.1 to the hollow shaft 11.
