FI4098987T3

FI4098987T3 - Measuring wheel set

Info

Publication number: FI4098987T3
Application number: FIEP22174514.4T
Authority: FI
Inventors: Andreas Brodtka; Lennart Ruberg; Olaf Schwabe; Philipp Meyer
Original assignee: Deutsche Bahn Ag
Priority date: 2021-06-04
Filing date: 2022-05-20
Publication date: 2023-11-15
Also published as: PT4098987T; ES2965829T3; EP4098987A1; DE102021114425A1; DK4098987T3; EP4098987B1; PL4098987T3; HUE064203T2

Claims

1 221745144 MEASURING WHEEL SET

The invention relates to a measuring wheel set, comprising two wheels connected by means of a wheel set shaft, at least one optical waveguide each having at least one optical filter inscribed into its fibre core, wherein the at least one optical waveguide is configured to be laid on a surface of at least one wheel or of the wheel set shaft, as well as at least one light source for coupling a light signal into the at least one optical waveguide.

Measuring wheel sets are known from the state of the art and are preferably used to measure forces or load conditions occurring between the wheels of a rail vehicle and the rails on which these wheels roll.

In an analogous manner, such measuring wheel sets are also suitable for measurements of forces occurring in similar pairings, such as between the wheels of a rail vehicle and the rail rollers of a roller dynamometer.

By means of such measurements, for example, the effects of different speeds, axle loads or contact geometries in the contact area between wheel and rail are investigated both on the respective wheel of the measuring wheel set or rail vehicle and on the rail or the associated track system.

For metrological evaluation, the measuring signals are transmitted by means of near-field telemetry from the measuring wheel set to a receiver spatially distanced from the measuring wheel set.

Usually, the receiver is located in the body of a track-bound measuring vehicle, which is supported on a rail track in a rollable manner by means of the measuring wheel set or a plurality of such measuring wheel sets.

US 2009/0301221 A1 discloses a measuring wheel set whose sensors are connected by means of electric cables to a signal evaluation apparatus mounted on the rotating wheel set shaft.

However, electrical data transmission means are susceptible to interference or distortion of data signals by the electric fields of traction motors of electrically driven rail vehicles.

In order to overcome these disadvantages, EP 2 246 681 A2 discloses a generic measuring wheel set on which an optical waveguide is arranged with at least one optical strain gauge accommodated therein.

The optical waveguide passes through an opening in the wheel set bearing and is connected to a rotary optical transmitter on the wheel set bearing housing, which in turn is coupled to a non-rotating data acquisition and processing unit.

In this way, the measurement signals recorded on the rotating wheel set can be transmitted to the non-rotating evaluation unit.

However, the production of such

2 221745144 a measuring wheel set is complex and expensive.

In addition, such mechanical processing necessary to produce the feedthrough of the optical waveguide prevents further use of the measuring wheel set in regular operational use after completion of the measurements,

The invention is therefore based on the object of providing a measuring wheel set comprising two wheels connected by means of a wheel set shaft, at least one optical waveguide each having at least one optical filter inscribed into its fibre core, wherein the at least one optical waveguide is configured to be laid on a surface of at least one wheel or of the wheel set shaft, as well as at least one light source for coupling a light signal into the at least one optical waveguide, which overcomes this disadvantage and which is inexpensive to produce.

According to the invention, this object is achieved in conjunction with the generic term of claim 1 in that the measuring wheel set further comprises at least one signal evaluation apparatus, configured for the detection and evaluation of light signals which are coupled into the optical waveguide and are modified by the at least one optical filter, which is in the form of a spectrometer arranged on the wheel set shaft or at a wheel of the measuring wheel set.

In this way, a set of measuring wheels can be realised which enables the simultaneous measurement of the entire wavelength spectrum of the light signals reflected by the optical filters based on their intensities at a discrete point in time.

In this way, the geometric dimensions and the mass of such an optical spectrometer can be minimised in such a way that there are no negative effects on the dynamic properties of the rotating measuring wheel set during intended use.

This means that its signal generation apparatuses and signal evaluation apparatuses can be installed on the measuring wheel set in a particularly simple manner, without the need for any mechanical processing on its wheel set shaft or wheels.

Likewise, once the measuring wheel set has been used for metrological purposes, it can be rebuilt into a conventional wheel set suitable for operational use by simply removing the optical waveguide.

For this purpose, the signal generation and signal evaluation apparatuses are located at points either on the inside or on the outside of the measuring wheel set. “Points on the inside of the measuring wheel set” are those mounting locations which, when the measuring wheel set is used as intended on a rail track, are located in the area above the track (i.e. on) the inside of a wheel facing the wheel set shaft, on the wheel set shaft, etc. ...); analogously to this, “points on the outside of the measuring wheel set” are to be

3 221745144 understood as those mounting locations which are located outside the track area when the measuring wheel set is used as intended on a rail track (i.e. for example on the “track- outward” facing outer surfaces of a wheel, on the wheel set bearing housing etc ...). In the context of the present invention, signal generation apparatus means the optical filters inscribed into the fibre core of an optical waveguide, which are designed to modify a light signal coupled into the optical waveguide as a function of the geometric spacings of the filter {e.g. spacings of the gratings of an interference filter from each other) influenced by mechanical loading of the optical waveguide.

The data transmission between signal generation and signal evaluation apparatus is done optically without electrical signals.

The optical waveguide can be laid in a simple manner on the surface of the component to be metrologically tested (i.e. as a rule a wheel) of the measuring wheel set (for example by means of bonding technology) in such a way that the positioning of the inscribed filters along the optical waveguide corresponds to the measuring locations at which measured values are to be recorded by sensors.

For this purpose, the optical waveguide is provided with a connector at its first distal end,

which is designed for connection to the signal evaluation unit.

Commercially available connectors are suitable for this purpose.

Furthermore, the optical waveguide is laid in such a way that — starting from the aforementioned connector to the signal evaluation apparatus — it follows a successive sequence of measurement locations, wherein each filter inscribed into the optical waveguide is attached to one such measurement location.

This means that the first filter — starting from the connection terminal to the signal evaluation apparatus — is mounted along the longitudinal extension of the optical waveguide at a first measuring point of the component, the second filter, which follows in series at an intermediate distance therefrom, is mounted at a second measuring point of the component, and so on.

As a result, all measuring locations of the component to be metrologically tested are connected to each other by means of the same optical waveguide.

In a most preferred manner, a plurality of optical waveguides with optical filters inscribed into the fibre core are provided, which can be connected to the same signal evaluation apparatus by means of separate connectors.

In this way, the total number of measuring locations of a measuring wheel set to be metrologically detected can be subdivided into a plurality of segments, wherein all measuring locations of each segment are detected by means of a common optical waveguide.

In this way, each segment can be

4 22174514.4 measured and analysed independently of the other segments.

In this way, it is possible to prevent a complete failure of the entire measurement technology in the event of damage to an optical waveguide or signal generation apparatus occurring during operation of the measuring wheel set.

In case of repair, only the optical waveguides or signal generation means affected by the damage need to be replaced.

This increases the reliability of the measuring wheel set according to the invention and allows a more flexible and easier configuration of the measuring wheel set.

This is effectively supported by bonding the optical waveguide to the surface of the component of the measuring wheel set to be metrologically tested.

In this way, optical waveguides can be easily replaced in the event of damage, and optical waveguides that are not required can be removed from the measuring wheel set without damage or residue.

In this context, the invention further provides that up to 40 optical filters are inscribed into the fibre core of an optical waveguide, wherein the individual optical filters can have different spacings from the respective adjacent filter.

In this way, the optical waveguides can be easily adapted to different geometries of the component to be metrologically tested and the resulting different positions of the measurement locations.

This also improves the more flexible and easier configuration of the measuring wheel set.

Precise positioning of the optical filters inscribed into the optical waveguide at the assigned measurement locations is possible by temporarily coupling in a light signal that is visible to the installation personnel during the installation process.

In this way, for example, by applying a continuous red laser light in the visible wavelength range, sharply defined luminous points can be created at the locations of the optical filters, which greatly facilitates manual alignment of the optical waveguide.

Preferably, the filters are interference filters or fibre Bragg gratings, each with an individual filter area.

Here, each filter covers a distinct wavelength range that is different from the filter ranges of the other filters on the same optical waveguide.

The fibre Bragg gratings can be inscribed into the glass fibre in a particularly simple manner using a laser light source in the UV spectrum (e.g. with light of wavelength A = 248 nm). As a result, the signals transmitted via the optical waveguide to the signal evaluation apparatus can be assigned to specific filters and thus at the same time to the specific measuring locations or measuring points on the measuring wheel set.

Furthermore, it is preferably provided that the light source for coupling light into the fibre core of the optical waveguide is integrated in the signal evaluation apparatus.

In this way, in the signal evaluation apparatus, both the coupling of the light signal and the evaluation of the light signals reflected at the various interference filters are carried out with different wavelengths in each case.

For this purpose, the signal evaluation apparatus includes a spectrometer for evaluating the light reflected from the interference filters.

By means of the

5 aforementioned clustering of the wavelength ranges of the reflected light, the signals reflected by the various interference filters can be measured and evaluated independently of one another.

The strain information specific to each filter is extracted from the light signal registered in the signal evaluation apparatus.

Since data transmission is exclusively optical, interference or distortion of data signals caused by the electric fields of traction motors of electrically driven rail vehicles is effectively avoided.

In addition, the optical waveguides are covered with a silicone layer, which improves their protection against mechanical damage.

According to a useful embodiment of the basic inventive concept, the at least one optical waveguide has sensors for measuring temperatures.

Preferably, these are designed as fibre Bragg gratings set up for temperature measurement.

These determine the temperature by measuring the changing refractive index of the grating as the glass material of the optical waveguide expands thermally.

This enables compensation of temperature-related influences on the measurement results.

The invention further provides that the measuring wheel set has a near-field telemetry device connected with the at least one signal evaluation apparatus for the transmission of data and energy.

This comprises a non-rotating stator and a rotor antenna, which is set up both for contactless transmission of the metrologically determined data from the signal evaluation apparatus installed on the measuring wheel set to a stationary or non-rotating device for further processing of the measured data and,

in the opposite direction to this, for contactless transmission of energy to the data acquisition unit.

In the case of measuring wheel sets designed as running wheel sets, for example, the wheel set bearing housing can form a suitable location for installing the stator; in the case of measuring wheel sets designed as driving wheel sets, this can be a gearbox or motor housing in the vicinity of the wheel set.

The rotor antenna and the signal evaluation apparatus are arranged in relation to each other in such a way that no holes need to be drilled in the measuring wheel set for the connecting line between the two and short connecting paths are realised between

6 221745144 the location of the measured value acquisition (i.e. the signal evaluation apparatus) and the location of the measured value transmission.

If the optical waveguide is laid on an inner side of a wheel of the measuring wheel set oriented towards the wheel set shaft, the rotor antenna and the signal evaluation apparatus are therefore preferably arranged in the inside area of the wheel set shaft located between the two wheels of the measuring wheel set.

Analogously to this, when the optical waveguide is laid on an opposite outer side of a wheel, the rotor antenna and the signal evaluation apparatus are preferably arranged on an outside part of the wheel set shaft oriented towards the wheel set bearing.

In this context, it is also advantageous to mount not only the signal evaluation apparatus but also the rotor antenna directly on the surface of the wheel set shaft (instead of, for example, mounting it inside a hollow wheel set shaft). This means that there is no need for holes, recesses, etc. in the wheel set shaft, which preserves the structural strength properties of the wheel set shaft and enables it to be reused later in the operational use of rail vehicles.

If individual components of the near-field telemetry device are designed in such a way that their attachment to the measuring wheel set could lead to dynamic imbalances during operation of the measuring wheel set (e.g. a measuring amplifier that does not completely encompass the circumference of the wheel set shaft), then they must be arranged on the measuring wheel set with regard to their position and alignment in such a way that compensation with the mass of the signal evaluation apparatus occurs.

The invention further extends to a rail vehicle having a measuring wheel set embodied in accordance with the foregoing features.

The invention will be illustrated in more detail based on an embodiment and related drawings.

The following are shown:

Figure 1: Wheel of a measuring wheel set in front view

Figure 2: Wheel of a measuring wheel set in side view

Figure 3: Alternative embodiment of the invention with the signal evaluation apparatus arranged on the inside

Figures 1 and 2 show a first embodiment of a measuring wheel set according to the invention, which is installed in a rail vehicle and by means of which the real forces and load conditions occurring between the rail vehicle and the rail tracks during operation of the rail vehicle are to be determined by measurement.

On the outwardly oriented side of

7 22174514.4 the wheel disc of this wheel, an optical waveguide (1) is laid, in whose fibre core 24 optical interference filters {4) are inscribed in the form of fibre Bragg gratings.

The optical waveguide (1) is attached to the wheel disc with adhesive and connected by means of a connector (7) to a signal evaluation apparatus (3) which is also bonded to the wheel disc.

Each fibre Bragg grating has an individual filter area and an individual spacing from the connector (7). The optical waveguide (1) can thus be laid on the wheel disc in such a way that a fibre Bragg grating is arranged at each of the measuring points of the wheel disc, which are known per se from the state of the art.

This results in the “cloverleaf-shaped arrangement” of the optical waveguide connecting the individual measuring points, which is characteristic of this metrological application and is clearly visible in Figure 1. The signal evaluation apparatus (3) has a light source which is set up to couple a light signal into the optical waveguide.

Furthermore, the signal evaluation apparatus (3) has means for receiving the light signals reflected from the fibre Bragg gratings, wherein the light reflected from each fibre Bragg grating is assigned to an individual or grating-specific wavelength spectrum.

In this way, the received signals can be easily assigned to a specific interference filter (4) or fibre Bragg grating and thus also to a specific measuring point.

The signal evaluation apparatus (3) is connected by means of a short connecting cable to a near-field telemetry device with integrated rotor antenna (6), which is arranged on the outside of the wheel set shaft oriented in the direction of the wheel set bearing and surrounds it in an annular manner.

By means of this transmission unit, both the measured value signals generated in the signal evaluation apparatus (3) by evaluating the signals received from the interference filters (4) are transmitted inductively via an air interface to a stationary device for further processing of the measured data (not shown in the figures of the embodiment example for reasons of clarity) and, in the opposite direction to this, control signals for controlling the signal evaluation apparatus (3). This has a stator antenna spatially aligned with the rotor antenna and is installed in the area of the wheel set bearing housing or the bogie frame of the rail vehicle.

The evaluation unit converts the strain information recorded by the measurement system into the corresponding forces.

All data transmission paths upstream of the air interface on the measuring wheel set are designed as optical transmission paths, which significantly improves the electromagnetic compatibility of the measuring wheel set and its insensitivity to electromagnetic interference.

As an alternative to inductive data transmission, transmission by radio would also be possible.

8 22174514.4

The energy required to operate the signal evaluation apparatus (3) and the near- field telemetry device is also transmitted inductively via the same air interface.

The power supply of a single signal evaluation apparatus (3) at 5 volts reguires the provision of a constant electrical output of 3 watts.

For parallel operation of a plurality of signal evaluation apparatuses, a correspondingly higher power transmission via the air interface is reguired.

Figure 3 shows an alternative second embodiment of the invention with the signal evaluation apparatus (3) arranged on the inside and the interference filters (4). The optical waveguide (1) with the interference filters (4) inscribed into its fibre core is applied to the inside of the wheel (2) facing the wheel set shaft (5). The signal evaluation apparatus (3) is bonded to the outer surface of the wheel set shaft in its inside area, i.e. between the two wheels of the measuring wheel set.

List of reference numerals:

1 Optical waveguide

2 Wheel

3 Signal evaluation apparatus

4 Interference filter

5 Wheel set shaft 6 Near-field telemetry device with integrated rotor antenna 7 Connector