|Title of Invention||
A WEIGHING DEVICE FOR RAIL VEHICLES
|Abstract||A WEIGHING DEVICE FOR RAIL VEHICLES|
THE PATENTS ACT, 1970
[39 OF 1970]
THE PATENTS RULES, 2003
[See Section 10; rule 13] "A WEIGHING DEVICE FOR RAIL VEHICLES"
SCHENCK PROCESS GMBH, of Landwehrstrasse 55, D-64293 Darmstadt,
The following specification particularly describes the nature of the invention and the manner in which it is to be performed:-
The invention relates to a weighing device for rail vehicles in accordance with the generic part of patent claim 1.
Some years ago, the weighing of rail vehicles was, in most cases, still carried out with the help of platform weighing scales, in which the total weight of an individual railway waggon was determined statically. In these platform scales, the rails on the weighing platform were separated from the running rails of the normal track system by gaps preceding and following the weighing platform. The weighing platform was mounted on at least four load cells and supported on a foundation. For this purpose, weighing platforms with the length of the waggons were needed, which required a very elaborate substructure of the platform consisting of concrete or steel components.
However, from EP 0 500 971 Al also dynamic weighing methods for rail vehicles which do not require an elaborate track base are known, in these methods, the shear strain is acquired in the neutral phase of the rail and evaluated. For this purpose, a strain-gauged weighing rail is welded into the normal track system, with at least two strain gauges arranged between the sleepers. The weight of the waggon is determined by adding up the weight signals measured for the individual axes. However, since the wheel load causes a deflection of the rail and the rail support, the train usually moves in a plane which is
located below the one which is determined by the unloaded rail, while at the same time vibrations in a vertical plane are generated due to the deflection of the rails between the sleepers. This leads, when a train in motion is weighed, to changes of the vertical forces and thus to measuring inaccuracies, which can only be avoided by a larger number of measuring points. Incidentally, such a weighing device is difficult to calibrate, since for this purpose static weighing devices are required, which today, in most cases, are available at a large distance only.
From DE 44 44 337 Al, a weighing device for rail vehicles for static and dynamic weight determination is known, in which load cells are arranged between the rails and a crossbeam, with the help of which the axle load of a railway waggon passing over the rails may be determined. In such a construction, the rails are provided with three recesses arranged one behind the other each in the rail foot and the rail stem, so that the rails are flexibly supported on the load cells. Due to this flexible support of the two sections of each rail, an elaborate foundation or frame structure is required in any case, which transmits the axle load into the ground. Moreover, the crossbeams consist, obviously, in I-beams, which cannot be installed into the the track system without major conversions.
For this reason, the invention is based on the problem of providing a weighing device for rail vehicles which requires only minor modifications in the rail net but with which, nevertheless, high accuracies can be achieved.
This problem is solved by the invention set forth in patent claim 1. Further developments and advantageous embodiments of the invention are described in the subclaims.
It is true that the use of the ballast glueing technique in which the ballast bed is stabilized with the help of an epoxy resin is known in track construction since 1988. The epoxy resin is sprayed onto the ballast bed with a hardener, and penetrates the ballast bed due to its viscosity, thus glueing the contact surfaces of the gravel together. However, this ballast glueing technique is employed in track construction mainly as a protection against projected gravel and in order to gradually increase the stability in the transition areas between ballast beds and solid beds. Anyway, the application of glue through the ballast as a support for a platform scale is not known.
An advantage of the invention is that the force measurement by means of weighing sleepers enables both static and dynamic weight measuring of rail vehicles. In particular, such a measuring device can easily be calibrated also for dynamic weight determination without having to resort to a platform scale located at a large distance.
A particular advantage of this invention is the fact that the entire weighing device consists just of one or several weighing sleepers which can be installed into the normal ballast bed just as other sleepers. Thus, no problems will arise with the transportation of long track sections or concrete and steel parts, which is necessary in case of static platform scales.
Another advantage of the invention is that the entire measuring equipment may be encapsulated into the concrete sleepers which are common today even during the manufacturing process, without much extra expenditure. With the help of such prefabricated weighing sleepers, platforms of varying lengths can easily be assembled, with, e. g., one weighing sleeper for single-axle weighing or with eight weighing sleepers for a
three-axle bogie, or with forty weighing sleepers for a complete high-precision waggon weighing procedure.
Another advantage df using such weighing sleepers is, in particular, the ease of maintenance, since in case of defects of the sensory equipment, in the worst case the entire weighing sleeper must be replaced just as any other normal sleeper. However, the load cells in the weighing sleepers may also be designed in such a way that they can be replaced individually, since they are always installed from above or from the side and are therefore easily accesible.
Another advantage of the invention is the fact that the weighing sleeper is glued into a ballast bed to which glue has been applied, which renders a platform construction, necessary for concrete or steel platforms, superfluous. In particular, such a stabilization of the ground can avoid abrupt changes in stiffness as occur in case of concrete or steel platforms, since a continuous stiffness increase or decrease is effected in a defined entry and exit area, so that the excitation of disturbing waggon vibrations due to the track support are reduced to a minimum during the weighing process.
In a special embodiment of the invention with shear strain sensors and/or recesses in the rail foot, the shunt force effect may be corrected or reduced by the uninterrupted rail track. This renders rail switches superfluous, which are otherwise required to identify the waggon type in in-motion weighing.
In a further, special embodiment of the invention, with dynamometers provided with force feedback elements, a particular advantage is that with the help of this measuring device, the weight can be determined very accurately even if the centre of gravity of the load input is horizontally
displaced and/or interferential forces or torques - as usual track systems - must be transmitted additionally.
The invention is further explained with an embodiment which is shown in the drawing. The figures show:
Fig. 1: schematic representation of a weighing device
with two weighing sleepers Fig. 2: a section of a weighing sleeper with a
dynamometer arranged underneath a rail.
In fig. 1 of the drawing,"a weighing device for rail vehicles with two glued-in weighing sleepers 2, 8 as crossbeams in a ballast bed 6 to which glue has been applied is shown, with one measuring eye 1, 11 being provided at the beginning and at the end of the weigh span in each rail as a shear stress sensor for shunt force correction in the area between the sleepers.
The two weighing sleepers 2, 8 are arranged in a ballast bed 6 which is common for trackways in railway construction. In this ballast bed 6, the two weighing sleepers 2, 8 are arranged just as conventional sleepers at right angles to the driving direction in parallel with each other, surrounded by the gravel forming the ballast bed 6. For consolidation, a two-package glue on an epoxy resin basis with hardener has been applied to the gravel, so that a glueing of the ballast is achieved by the liquid glue penetrating the ballast bed 6. In this process, also the weighing sleepers 2, 8 are glued into the gravel. This ballast glueing technique is already commom in track construction as a protection against projected gravel on high-speed railway lines and for stabilization in the transition areas between trackways in a ballast bed and trackways in a solid bed. Furthermore, such a ballast glueing method is already widely used for stabilization purposes at
points and on the verges of trackways in stations.
In the area of the weighing device, it has proven favorable to glue the ballast in the area approx. one waggon length preceding and one waggon length following the weighing sleeper or weighing sleepers 2, 8 and that the glueing reaches up to a depth of 0.5 m, depending on the load. The ballast stones are glued to each other at their edges or points of contact, thus forming a solid, stabilized ballast bed 6. The degree of stabilization of the ballast bed 6 depends on the amount and the penetration depth of the two-package glue. Thus, various degrees of stabilization of the ballast bed may be brought about, so that in particular a gradual increase of the consolidation or stiffness at the beginning and/or a gradual decrease at the end of the weighing device are advantageous. In this stabilized ballast bed 6, the weighing sleepers 2, 8 are glued into the bed, so that a frictional connection also arises between the weighing sleepers 2, 8 and the ballast bed 6.
Substantially, the weighing sleepers 2, 8 are designed as normal sleepers, with the only difference that the dynamometers are integrated into them. The weighing sleepers
2, 8 consist, like conventional sleepers, preferably out of
reinforced concrete and are made in a concrete casting
process. However, the weighing sleepers 2, 8 may also be made
out of other materials appropriate for the production of
In the concrete sleepers, recesses 4, 9 are provided in the area of the supporting points of the rails, into which the dynamometers 3, 10 may be inserted. However, the dynamometers
3, 10 may also be permanently installed in a prefabricated
housing, which is encapsulated in the concrete sleepers..In
addition., cable ducts 25 are provided in the weighing sleepers
2, 8, in which the wires of the measuring device are laid.
eferably, these cable ducts 25 extend from the recesses 4, 9 of the dynamometer 3, 10 up to the centre of the sleeper, where they end in a further recess 24, in which the interconnecting is effected. In this recess 24, however, electronic circuits for measured value processing and power supply may be arranged at the same time. This wiring-up recess 24 of each weighing sleeper 2, 8 is connected with the other weighing sleepers via a connection channel 5, which connects these devices to a central evaluation unit 12.
The dynamometers 4, 10 provided in the recesses 4, 9 are equipped, on their upper sides, with linking elements, establishing a firm connection with the rail 7 located above. Preferably, for this purpose clamping joints 15, 14 are provided, like the ones which are commonly used for linkage to the rails 7 on the remaining sleepers. Nevertheless, other linking elements may be provided as well, if this is necessary or favorable due to the design of the dynamometers 3, 10.
In the area of the weighing device, the rails 7 are not interrupted and constitute common running rails. The entire weighing device consists of, preferably, six to eight weighing sleepers 2, 8 which are appropriate for the weighing of railway waggons or other rail vehicles with up to three-axle bogies and cover a weigh span of 4 to 5 m. In the described embodiment, however, only two weighing sleepers 2, 8 are represented for reasons of clearness. For weight determination of rail vehicles with only two axles, weighing devices with just one weighing sleeper 2, 8 would be sufficient. In case of extremely high accuracy requirements and for static weighing of complete railway waggons, it is also possible to provide weighing devices with forty weighing sleepers 2, 8 with a weigh span of 25 m.
For correction of the shunt force effect, a so-called measuring eye 11 is provided as a shear strain sensor in the neutral phase of each rail 7 at the beginning and/or at the end of the weigh span in the middle between the first or the last weighing sleeper 2, 8 and the adjacent sleeper. With the help of such a measuring eye 11,. the shear strain occuring in the neutral phase of each rail 7 when a vehicle axis passes over it may be measured quite easily. For this purpose, measuring eyes 11 which are designed as circular transducer units with strain gauges have proven favorable. Preferably, these measuring eyes 11 may easily be fixed in a hole in the neutral phase of each rail. However, these shear strain transducers 11 may well have a different design, e. g. they may be attached directly at the rail stem.
These shear strain transducers 11 measure a force when an axis of a rail vehicle passes over, depending on the shunt force • effect, which distorts the weighing result measured by the dynamometers 3, 10 in the weighing sleepers 2, 8. The stronger this coupling to the dynamometer 3, 10, the greater the distortion by the shunt force effect. If only one weighing sleeper .2, 8 is provided, a relatively big shunt force error will result. In case of a weighing device with several weighing sleepers 2, 8, this shunt force error is correspondingly reduced.
However, due to the mentioned"determination of the shear strain, this error may be corrected by a corresponding calibration. For this purpose, both the signals of the shear strain sonsors 11, 1 and those of the dynamometers 3, 10 of each weighing sleeper 2,8 are transmitted to a central evaluation device 12. With the help of one or several known reference masses or reference dynamic effects (e. g. by a testing device), the- weighing device may be calibrated statically at first. During this process, the shunt force
effect, depending on the location, is measured with the help of the shear strain sensors 1, 11. For this purpose, a reference mass or the testing device is put down in various positions of the weigh span. Alternatively, this procedure can also be carried out with a.moving reference mass in an automated way. In the central evaluation unit 12, the correction functions derived from the shear strain measurements of the calibration process are stored. Subsequently, the static weights for the unknown masses may be determined. With these weights, in turn, the weighing device may be calibrated dynamically. The dynamic correction functions determined in this process are also stored in the central evaluation unit 12. That means that it is. possible to calibrate such a weighing device in a simple way with known reference masses or a testing device and further unknown masses both statically and dynamically. The weighing signal in the central evaluation unit 12 that has been calibrated in this way may be required or indicated by a further unit at the output of the central evalution unit for the purpose of further processing or for indication.
However, by providing a recess in the rail foot and rail stem the shunt force effect may be reduced to such a degree that its influence on the measuring result is insignificant. For . this purpose, a recess in the rail foot and stem is provided preceding the first weighing sleeper 8, which does, however, not interrupt the part which is passed over, so that a , flexible coupling is brought about. The greater the distance at which this joint is arranged from the first measuring sleeper 8 without support and the less bending stress is transmitted by the joint, the lower the shunt force effect. However, since a certain degree of shear strain may not be exceeded in this joint so that it will not be damaged when an admissible load passes over it, a certain degree of shunt force effect cannot be avoided. For this reason, it has proven
particularly favorable to provide a recess in each rail in addition to the shear strain measurement, so that - especially with small loads passing over - an accurate in-motion weighing is still achieveable, with the platform length being as short as possible. The measuring result may be improved especially by providing a recess and carrying out a shear strain measurement both at the beginning and at the end of the weigh span.
The shear strain sensors 1, 11 are simultaneously used as rail switches. For this purpose, the beginning and the end of a vehicle passing over is determined by the central evaluation unit 12 with the help of given axle bases of known rail vehicles. On the basis of the known and the measured axle bases, the vehicle weight may then be determined in the evaluation unit 12
In fig. 2 of the drawing, a dynamometer 3 is represented in detail as a sectional drawing of a section- of a weighing sleeper 2. In this figure, the same reference numbers have been used as for parts with identical functions in fig. 1 of the drawing. The weighing sleeper 2 contains a dynamometer 3 which is firmly installed in a housing 22 which is encapsulated in the sleeper. It is useful that this housing unit 22 is equipped with reinforcing elements 23, which ensure a non-separable connection with the reinforced concrete sleeper 2. In this housing unit 22, a dynamometer 3 is. provided as a load cell, which is arranged below the rail 7. This load cell 3 contains a load input element 18, a deformation element 17 to which strain gauges 20 are attached and a load output element 21, which is permanently fixed to the housing 22. This load cell 3 has the shape of an S, so that the load input elements 18 and the load output elements 21 are simultaneously designed as force feedback elements. The load input element 18 and the load output element 21 are
separated from the deformation element 17 by horizontal slots 16, 26. In its centre, the deformation element 17 contains two horizontal pocket holes 19 in opposite directions, so that between the two holes a vertical deformation area remains, to which strain gauges 20 are fixed. These generate a signal which is proportional to the weight on rail 7.
At the load input element 18, webs with clamping elements 14 are provided, between which the rail 7 runs at right angles to the load cell 3 and is permanently bolted with the latter. Favorably, load cells 3 with force feedback elements 18, 21 are provided, since in these the measured force is largely independent of the point of load input, so that displacements of the centre of gravity on rail 7 do not influence the measuring result. Therefore, it is also an advantage to use weighbeams with force feedback elements, in which case the rail 7 would be fixed to an upper feedback element, whereas a lower feedback element would have to be firmly connected to the housing 22.
The dynamometers 3, 10 may also be designed in such a way that they are separably connected to the housing 22. For this purpose, it is particularly favorable to use srewed connections, so that, in case of damage, the individual measuring devices 3, 10 may be replaced individually from above after lifting the rail. The housing 22 of the dynamometers 3, 10 could also be approached up to the end of the sleeper and provided with a separable lateral part, allowing the dynamometer 3, 10 to be replaced favorably from the side, without the need to lift rail 7.
In longitudinal direction of the weighing sleeper 2, a horizontal cable duct 25 is provided, in which the wiring to the strain gauges 20 and the measuring eyes 1, 11 is arranged so that it cannot be damaged. The cable duct 25 ends in the
middle of the weighing sleeper 2, 8 in a recess for interconnecting purposes 24, in which, additionally, electric circuits are arranged, which serve for power supply and for conversion of the measuring signal (A/D converter)independent of the distance.
Above the interconnection recess 24, a tubular connecting channel 5 is provided in the direction of the rail, which connects the weighing sleepers 2, 8 electrically with each other and with a central evaluation unit.
1. A weighing device for rail vehicles wherein at least one dynamometer (3, 10) is arranged between at least one running rail (7) and at least one crossbeam (2, 8), with the dynamometer forming a weigh span that produces a signal which is proportional to the load on the rail, characterized in that preceding the first dynamometer (3, 10), at least one additional shear strain sensor (1, 11) is arranged at at least one running rail (7) for determination of the shunt force coupling, and whose measuring signals are used for correction of the shunt force coupling.
2. The weighing device as claimed in claim 1, wherein a shear strain
sensor (i, II) is provided at least preceding the first and following the
last dynamometer (3, 10) of the weigh span, with the shear strain
sensor (1, 11) being arranged in the neutral phase of the fail (7).
3. The weighing device as claimed in claim 1 or 2, wherein on the basis
of the shear strain measurement and a static calibration, a location-
dependent correction function, which is used to take account of the
shunt force coupling in a dynamic weighing process, is formed and
stored in a central evaluation unit (12).
4. The weighing device as claimed in one of the preceding claims, wherein load cells (3) are provided as dynamometers (3, .10), whose weigh signals are linked in such a way that the weight of the rail
vehicles or parts thereof may be determined on the basis of the measuring signals.
The weighing device as claimed in one of the preceding claims, wherein the signals of at least one shear strain sensor (11) serve, at the same time, as rail switch, and that on the basis of these signals a waggon beginning or waggon end or bogie beginning or bogie end is determined in the evaluation unit (12) with the" help of given axle bases.
The weighing device as claimed in one of the preceding claims, wherein the said shear strain sensor (11) is designed as a measuring eye, which is arranged in a hole of the rail (7) or is formed by directly attached strain gauges.
The weighing device as claimed in one of the preceding claims, wherein at least preceding the said first dynamometer (3, 10), a vertical or inclined downwardly open recess is provided in the rail foot, connecting the said running rail (7) flexibly with the said dynamometer or dynamometers (3, 10).
The weighing device as claimed in any one of the preceding claims, wherein at least preceding the first and/or the last dynamometer (3, 10), a vertical or inclined downwardly open recess is provided in the
rail foot, which connects the said running rail (7) flexibly with the said dynamometer or dynamometers (3, 10).
The weighing device as claimed in claim one of the preceding claims, wherein the said dynamometer (3, 10) for each rail (7) is arranged between the said corresponding rail (7) and a crossbeam.
The weighing device as claimed in one of the preceding claims, wherein the said crossbeam is designed as a weighing sleeper (2, 8) in which the dynamometers (3, 10) are integrated and which are supported on a stabilized ground.
The weighing device as claimed in one of the preceding claims, wherein the said weighing device comprises at least one weighing sleeper (2, 8) or a multitude of weighing sleepers (2, 8).
The weighing device as claimed in one of the preceding claims, wherein the said weighing sleeper (2, 8) consists of reinforced concrete or another material which is suitable for the production of sleepers.
The weighing device as claimed in one of the preceding claims, wherein each said weighing sleeper (2, 8) contains at least two recesses (4, 9) for integration of the dynamometers (3, 10), which are provided below rail support.
The weighing device as claimed in one of the preceding claims, wherein in the said recesses (1, 9), dynamometers (3, 10) are arranged, whose load input element (18) is friction and torque-locked with the rail (7) and whose load output element (21) is friction and torque locked with the sleeper (2, 8).
The weighing device as claimed in one of the preceding claims, wherein the dynamometer (3, 10) is fixed in*a firm housing part (22) which is cast together with the sleeper (2, 8) or permanently connected with same by other means of connection.
The weighing device as claimed in one of the preceding claims, wherein the said dynamometer (3, 10) is connected to the said housing part (22) by means of a separable connection, with the said housing part (22) being equipped with an upper or laterally removable cover part, enabling the dynamometer (3, 10) to be replaced.
The weighing device as claimed in one of the preceding claims, wherein the dynamometer (3, 10) is embodied as a load cell with feedback elements (18, 21).
this 18th day of June, 2001.
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANTS
|Indian Patent Application Number||IN/PCT/2001/00725/MUM|
|PG Journal Number||16/2007|
|Date of Filing||18-Jun-2001|
|Name of Patentee||SCHENCK PROCESS GMBH|
|Applicant Address||OF LANDWEHRSTRASSE 55, D-64293 DARMSTADT, GERMANY.|
|PCT International Classification Number||N/A|
|PCT International Application Number||N/A|
|PCT International Filing date||1999-12-17|