Determining the wear of a contact strip
Patent Information
- Application Number
- EP2024702255
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-02-10
- Filing Date
- 2024-01-18
- Publication Date
- 2025-10-22
AI Technical Summary
Current methods for determining the wear of pantograph contact strips in rail vehicles are inaccurate and labor-intensive, leading to premature replacement and increased risk of energy transmission failure, especially in multi-system vehicles with limited redundancy.
The implementation of a system using central and partial magnetic field sensors to measure the magnetic fields caused by contact wire currents, allowing for precise determination of contact strip thickness and wear status without manual measurements, by calibrating the sensors on new strips and comparing signals from used strips.
Enables accurate and timely assessment of contact strip wear, extending its usage, reducing maintenance and replacement costs, and ensuring reliable energy transmission by providing a real-time, precise measurement of remaining operational range.
Smart Images
Figure EP2024051120_15082024_PF_FP
Abstract
Description
[0001] Description
[0002] Wear determination of a grinding bar
[0003] The invention relates to an arrangement and a method for determining the wear of a used contact strip of a rail vehicle pantograph.
[0004] A rail vehicle's pantograph is equipped with one or two pairs of contact strips. The contact strips wear out as the rail vehicle moves in contact with a designated overhead electric line. The contact strips must be replaced as soon as a predetermined limit, such as a minimum thickness, is reached on at least one of the pairs.
[0005] If the minimum thickness or strength required as a limit value is significantly undercut, there is a risk of energy transmission failure via the contact strip and thus a failure of the rail vehicle.
[0006] Pantographs are often equipped with a so-called "automatic drop down" system, which automatically lowers the pairs of loop strips when the minimum thickness is reached or exceeded.
[0007] A worn contact strip is particularly critical in so-called multi-system vehicles, which use different energy supply systems (AG overhead line, DC overhead line, ...) to alternately drive the rail vehicle.
[0008] Due to the limited installation space on these rail vehicles, often only one pantograph is provided on board the rail vehicle for an energy supply system, for which there is no additional pantograph for any possible redundancy.
[0009] During periodic maintenance of the pantograph or its contact strips, the current condition or the current thickness of the contact strips is determined by measurements (e.g. using a caliper, measuring template, or similar).
[0010] The current condition of the grinding strips is determined by:
[0011] - the distance travelled,
[0012] - the average speed of the rail vehicle,
[0013] - the friction between the overhead line and the contact strip,
[0014] - the thermal stress on the contact strip during current transmission,
[0015] - the contact situation between the contact strip and the overhead line, which is caused and influenced by ice formation, wear, surface structure, sparking, etc.,
[0016] - etc .
[0017] After the measurement has been completed, maintenance specialists will make a rough estimate based on their experience as to whether the contact strip in question can continue to be used for the intended future range or whether it needs to be replaced.
[0018] If subsequent operating conditions for the maintained rail vehicle are more demanding than expected, the estimated range does not reflect reality, increasing the probability of failure of the maintained rail vehicle. To address this problem, maintenance specialists tend to estimate the future range conservatively, resulting in the preventative disposal of the contact strips, even if they could still remain in operation for a longer period.
[0019] Apart from maintenance, the remaining strength or thickness of a used contact strip and the associated remaining range of the rail vehicle at a desired time cannot currently be determined or estimated.
[0020] It is therefore the object of the present invention to provide an improved method and a suitable arrangement for determining the wear of contact strips in a rail vehicle pantograph in order to determine at any given time the remaining strength or thickness of the used contact strips.
[0021] This problem is solved by the features of patent claim 1. Advantageous further developments are specified in the dependent patent claims.
[0022] The invention relates to an arrangement and a method for determining the wear of a contact strip (SL) of a rail vehicle pantograph.
[0023] A sanding strip has a central section, a first partial section, and a second partial section along its length. The central section is located (preferably centrally) between the two partial sections.
[0024] A contact wire contacts the contact strip to feed a contact wire current into the contact strip. The contact wire current is then split into a first partial current, which flows in the first sub-area, and a second partial current, which flows in the second sub-area.
[0025] The two partial streams are essentially the same size.
[0026] A central magnetic field sensor is provided to monitor the central area, so that the central magnetic field sensor measures a central magnetic field caused by the contact wire current at a distance that includes a thickness of the contact strip in the central area.
[0027] A first magnetic field sensor is provided for monitoring the first partial area, such that the first magnetic field sensor measures a first magnetic field caused by the first partial current at a distance that includes a thickness of the contact strip in the first partial area. A second magnetic field sensor is provided for monitoring the second partial area, such that the second magnetic field sensor measures a second magnetic field caused by the second partial current at a distance that includes a thickness of the contact strip in the second partial area.
[0028] During calibration, the magnetic field sensors are arranged on an unused contact strip for area monitoring in such a way that the electrical signals formed from the measured magnetic fields have a summed signal value of zero.
[0029] When a grinding strip is subsequently used, the electrical signals formed from the measured magnetic fields have a summed signal value that is not equal to zero.
[0030] The total signal value of the grinding strip used is
[0031] Vehicle diagnostic device which, based on this and in comparison to the calibration, determines the current thickness of the grinding strip used in the middle area.
[0032] In an advantageous further development, the contact wire contacts the contact strip on a first side of the contact strip in a back and forth movement.
[0033] In an advantageous further development, the central magnetic field sensor is arranged on a second side of the grinding strip opposite the first side.
[0034] In an advantageous further development, the first magnetic field sensor is arranged on a second side of the grinding strip opposite the first side.
[0035] In an advantageous further development, the second magnetic field sensor is arranged on a second side of the grinding strip opposite the first side.
[0036] In an advantageous embodiment, the grinding strip is connected to a grinding strip holder. At least one of the magnetic field sensors is preferably attached to the grinding strip holder.
[0037] In an advantageous further development, the contact wire and the contact strip are preferably aligned to one another in the contact area and are essentially perpendicular to one another in order to form a system geometry.
[0038] In an advantageous further development, the system geometry arranges the first and the second magnetic field in respective parallel planes which are orthogonal to the plane of the central magnetic field, so that the magnetic fields are decoupled from one another via their distance and via the orthogonality for the magnetic field measurement.
[0039] In an advantageous further development, the sums of the signals from the magnetic field sensors are processed based on their mean values, preferably at predetermined time intervals.
[0040] In an advantageous further development, calibration is carried out each time an unused contact strip is installed on the rail vehicle.
[0041] In an advantageous further development, the calibration is carried out at room temperature of the pantograph.
[0042] The present invention makes it possible to determine the actual strength or thickness of the sanding strip used at any time.
[0043] This enables an improved estimation of the future or remaining range of the rail vehicle over the contact strip under consideration.
[0044] The present invention enables an improved or extended use of the grinding strip, which is based on actual wear and is free from estimates.
[0045] The present invention makes it possible to determine the strength or thickness of the sanding strip used with high precision and without the need for manual measurements.
[0046] This saves time, effort, and ultimately costs in both maintenance and sanding strip replacement. The invention is explained in more detail below with the aid of a drawing. It shows:
[0047] FIG 1 shows a view of currents and magnetic fields in a contact strip as a basis for the present invention,
[0048] FIG 2 with reference to FIG 1 magnetic field sensors used according to the invention,
[0049] FIG 3 with reference to FIG 1 and FIG 2 an overview of the magnetic field sensors, magnetic fields and currents in an unused contact strip,
[0050] FIG 4 with reference to FIG 3 a plan view of the grinding strip, and
[0051] FIG 5 with reference to the previous figures an overview of the magnetic field sensors, magnetic fields and currents in a worn contact strip.
[0052] FIG 1 shows, as a basis for the present invention, a consideration of currents I, II, I2 and magnetic fields B, B1, B2 in a contact strip SL which is in contact with a contact wire FD.
[0053] A contact wire current I flows from the contact wire FD into the contact strip SL and branches there into a first partial current II and a second partial current 12 in order to reach further components inside the rail vehicle via associated strands LI, which are provided at both ends of the contact strip SL.
[0054] The first partial flow II flows through a first partial area TB1 of the contact strip SL, while the second partial flow 12 flows through a second partial area TB2 of the contact strip SL. The two partial flows II, 12 are approximately equal, but directed oppositely to each other.
[0055] This means that the following applies to their amounts:
[0056] 1 = 11 + 12.
[0057] The contact wire current I flowing in the contact wire FD generates a magnetic field referred to as the central magnetic field B. Its approximately circular and closed induction lines lie in a plane orthogonal to the longitudinal axis of the contact wire FD.
[0058] According to the well-known "Biot-Savart law z", the magnetic field strength of the central magnetic field B is inversely or indirectly proportional to a considered distance r from the contact wire FD.
[0059] So: B ~ 1 / r
[0060] The first partial current II generates a first magnetic field Bl, whose approximately circular and closed induction lines lie in a plane that is orthogonal to the longitudinal axis of the contact strip SL.
[0061] A magnetic field strength of the first magnetic field Bl is inversely or indirectly proportional to a considered distance from the contact strip SL, so that:
[0062] Bl ~ 1 / distance.
[0063] The second partial current 12 generates a second magnetic field B2, whose approximately circular and closed induction lines lie in a plane that is orthogonal to the longitudinal axis of the contact strip SL.
[0064] A magnetic field strength of the second magnetic field B2 is inversely or indirectly proportional to a considered distance from the grinding strip SL, so that
[0065] B2 ~ 1 / distance .
[0066] FIG 2 shows, with reference to FIG 1, magnetic field sensors SEN, SEN1 and SEN2 of the contact strip SL used according to the invention and their signals S , S 1 and S2 .
[0067] In advance, the following consideration is carried out for the two contact strips of a pantograph shown here:
[0068] - Pantographs are generally equipped with two contact strips. Power is often supplied from the contact wire of an overhead line via the two contact strips from two substations, each located before and after a corresponding contact point.
[0069] - Since the two contact strips are at the same electrical potential, it can be assumed that the current flowing in a section of wire between the two contact strips is negligibly small compared to the current drawn by each individual contact strip.
[0070] - This makes it possible to analyse in the present invention only a simplified case in which only one contact strip SL takes the contact wire current I from the contact wire FD.
[0071] The contact wire FD and the contact strip SL are aligned perpendicular to each other, so that a special system geometry is formed: - the magnetic fields Bl and B2 lie in respective parallel planes,
[0072] - these planes are each orthogonal to the plane in which the central magnetic field B lies.
[0073] In the area of the contact strip SL, preferably on an associated contact strip holder, magnetic field sensors SEN, SEN1 and SEN2 are mounted, which detect the respective magnetic field strengths of the magnetic fields B, B1, B2 at the mounting points and convert them into electrical signals S, S1 and S2 respectively.
[0074] A central magnetic field sensor SEN is arranged below and in a middle or central area MB of the contact strip SL.
[0075] Preferably, the central sensor SEN is attached to a grinding strip holder which carries the grinding strip SL.
[0076] The central magnetic field sensor SEN is positioned in the middle area MB of the contact strip SL at a distance from the contact wire FD due to its mounting position and the thickness of the contact strip SL, and at this position detects the magnetic field strength of the central magnetic field B. The central magnetic field sensor SEN converts this magnetic field strength into an electrical (central) signal S of the central sensor SEN.
[0077] A first magnetic field sensor SEN1 is arranged below and in the first partial area TB1 of the contact strip SL.
[0078] Preferably, the first sensor SEN1 is also attached to the grinding strip holder.
[0079] The first magnetic field sensor SEN1 has a predetermined distance from the central magnetic field sensor SEN. The first magnetic field sensor SEN1 has in the first partial area
[0080] TB1 determines a distance to the grinding strip SL based on its mounting situation and the thickness of the grinding strip SL.
[0081] The first magnetic field sensor SEN1 detects the magnetic field strength of the first magnetic field Bl at this position and converts this magnetic field strength into an electrical first signal S 1 of the first sensor SEN1.
[0082] A second magnetic field sensor SEN2 is arranged below and in the second partial area TB2 of the contact strip SL.
[0083] Preferably it is also attached to the sanding strip holder.
[0084] The second magnetic field sensor SEN2 has the same predetermined distance from the central magnetic field sensor SEN as the first magnetic field sensor SEN1 has from the central sensor SEN. Thus, the two magnetic field sensors are arranged mirror-symmetrically to the central magnetic field sensor SEN.
[0085] The second magnetic field sensor SEN2 has a distance to the contact strip SL in the second partial area TB2 due to its mounting situation and the thickness of the contact strip SL.
[0086] The second magnetic field sensor SEN2 detects the magnetic field strength of the second magnetic field B2 at this position and converts this magnetic field strength into an electrical second signal S2 of the second sensor SEN2.
[0087] Due to the special system geometry and the positions of the sensors SEN, SEN1 and SEN2 described above, - the central magnetic field sensor SEN, which detects the central magnetic field B, is insensitive to the two magnetic fields Bl and B2,
[0088] - that the first magnetic field sensor SEN1 , which detects the first magnetic field Bl , is insensitive to the central magnetic field B ,
[0089] - that the second magnetic field sensor SEN2 , which detects the second magnetic field B2 , is insensitive to the central magnetic field B ,
[0090] - that due to the spatial distance between the first magnetic field sensor SEN1 and the second magnetic field sensor SEN2, the first magnetic field sensor SEN1 is insensitive to the second magnetic field B2, and
[0091] - that due to the spatial distance between the first magnetic field sensor SEN1 and the second magnetic field sensor SEN2, the second magnetic field sensor SEN2 is insensitive to the first magnetic field Bl.
[0092] FIG 3 shows in a side view and with reference to FIG 1 and FIG 2 an overview of the magnetic field sensors or sensors SEN, SEN1, SEN2, the magnetic fields B, B1, B2 and the currents I, II, I2 for an unused or unworn contact strip SL.
[0093] The central magnetic field sensor SEN is located rather far away from the contact wire FD due to the unused contact strip SL, so there is typically a distance of > 40 mm between the two.
[0094] The special system geometry described above makes it possible to calibrate the magnetic field sensors SEN, SEN1, and SEN2 via their respective positioning. Calibration is performed in such a way that the electrical signals S, S1, and S2 assume a signal value of "0" when the contact strip SL is unused or unworn and a contact point between the contact wire FD and the contact strip SL is in the center of the contact strip SL.
[0095] This leads to the following equation with a signal SO as the resulting signal from the sensors SEN, SEN1 and SEN2:
[0096] SO = SI + S2 - S = 0
[0097] This configuration corresponds to an equilibrium state in which the effects of the magnetic fields B, B1 and B2 generated by the currents I, II and B2 cancel each other out.
[0098] During the operational operation of the rail vehicle, the contact wire FD is actively guided back and forth via the contact strip SL, whereby this active guidance is realized by suspending the contact wire FD along the route traveled by the rail vehicle.
[0099] This means that in the middle area MB of the grinding list SL there is a higher material removal on the surface of the grinding bar SL than is the case on the surface of the grinding bar (SL) in the two partial areas TB1, TB2 of the grinding bar SL.
[0100] As shown above, the magnetic field sensors SEN1 and SEN2 are positioned laterally in the sub-areas TB1 and TB2 and below the contact strip SL or at corresponding locations on the contact strip holder. The central magnetic field sensor SEN is positioned in the central or middle area and below the contact strip SL or at a corresponding location on the contact strip holder.
[0101] The central magnetic field sensor SEN monitors the thickness of the grinding strip SL in the middle area MB .
[0102] The sensors SEN1 and SEN2 monitor the thickness of the grinding strip SL in the corresponding sub-areas TB1, TB2 of the grinding strip SL.
[0103] FIG 4 shows a plan view of the grinding strip SL with reference to FIG 3.
[0104] FIG 5 shows, with reference to the preceding figures FIG 1 to FIG 4, an overview of the magnetic field sensors SEN, SEN1, SEN2, the magnetic fields B, B1, B2 and the currents I, II, I2 in the case of a worn contact strip SL.
[0105] Compared to FIG 3, the central magnetic field sensor SEN, which is arranged in the middle area MB of the contact strip SL, is now closer to the contact wire FD due to the increased material removal there.
[0106] Typically, there is now a distance of well < 40 mm between the two, for example 25 mm.
[0107] The value of 25 mm is often taken as the operating limit and represents a minimum thickness for the SL grinding strip.
[0108] Due to the increased material removal in the central area MB, the corresponding signal S of the central magnetic field sensor SEN changes compared to the calibration described above, while the signals S 1 and S2 of the two corresponding magnetic field sensors SEN1 and SEN2 remain essentially the same.
[0109] Due to the Biot-Savart law, this is due to the fact that the sensors SEN1 and SEN2 maintain their distance from the source of the magnetic fields B1 and B2 almost unchanged (because they are installed below less stressed sections of the contact strip), while the central magnetic field sensor SEN continues to reduce its distance from the source of the magnetic field B (contact wire FD, current I) due to the material removal.
[0110] The increased material removal in the central area MB of the grinding strip SL leads to a change in the geometry and thus to a change in the equilibrium set during calibration.
[0111] For the worn grinding strip SL shown, the following now applies:
[0112] SO = SI + S2 - SV 0 .
[0113] The electrical signal SO is processed accordingly and transmitted to a receiving device of a vehicle diagnostic device.
[0114] The vehicle diagnostic device is preferably designed as part of the rail vehicle or is part of a remote monitoring system with which the rail vehicle is monitored via a fixed control point, which is referred to as the landside.
[0115] The wear condition of the SL contact strip is monitored with the aid of the vehicle diagnostic device, whereby this monitoring is current at all times with regard to the wear condition and can be carried out continuously.
[0116] Despite the generally high system voltages, the sensors SEN, SEN1 and SEN2 require only a small amount of energy to generate signals.
[0117] This allows the sensors SEN, SEN1, SEN2 to be powered by a rechargeable and / or replaceable battery, the battery being provided in the sensor.
[0118] This avoids additional cabling of the magnetic field sensors on the rail vehicle with all its disadvantages.
[0119] Preferably, the magnetic field sensors are protected from temperature fluctuations that occur during operation of the rail vehicle. This ensures that signal measurements can be performed reliably at any temperature.
[0120] The signals S, S1, and S2, which contribute to the formation of SO, are preferably processed based on their mean value rather than their instantaneous value. This reduces the influence of deviations, particularly those caused by temperature fluctuations.
[0121] Preferably, the mean values are calculated at specified time intervals.
[0122] The described calibration for specifying or setting SO = 0 is preferably performed each time a new, i.e., unused, contact strip is installed on the rail vehicle. Calibration is preferably performed at room temperature and under non-operating pantograph conditions.
Claims
Patent claims 1. Arrangement for determining the wear of a contact strip (SL) of a rail vehicle pantograph, - with a contact strip (SL) which has a central region (MB), a first partial region (TB1) and a second partial region (TB2) in its length, the central region (MB) being arranged between the two partial regions (TB1, TB2), - with a contact wire (FD) which contacts the contact strip (SL) in order to feed a contact wire current (I) into the contact strip (SL), which is divided there into a first partial current (II) which flows in the first partial area (TB1), and into a second partial current (II2) which flows in the second partial area (TB2), - in which a central magnetic field sensor (SEN) is provided for monitoring the central area (MB), so that the central magnetic field sensor (SEN) measures a central magnetic field (B) caused by the contact wire current (I) at a distance which includes a thickness of the contact strip (SL) in the central area (MB), - in which a first magnetic field sensor (SEN1) is provided for monitoring the first partial area (TB1), so that the first magnetic field sensor (SEN1) measures a first magnetic field (B1) caused by the first partial current (II) at a distance which includes a thickness of the contact strip (SL) in the first partial area (TB1), - in which a second magnetic field sensor (SEN2) is provided for monitoring the second partial area (TB2), so that the second magnetic field sensor (SEN2) measures a second magnetic field (B2) caused by the second partial current (12) at a distance which includes a thickness of the contact strip (SL) in the second partial area (TB2), - in which, during calibration, the magnetic field sensors (SEN, SEN1, SEN2) are arranged on an unused contact strip (SL) for area monitoring in such a way that electrical signals (S, S1, S2) formed from the measured magnetic fields (B, B1, B2) summed up to have a total signal value of zero, - in which, in a subsequently used contact strip, electrical signals (S, S1, S2) formed from the measured magnetic fields (B, B1, B2) summed up have a total signal value that is not equal to zero, which is fed to a vehicle diagnostic device (EDV) in order to determine, based thereon and in comparison to the calibration, a current thickness of the used contact strip (SL) in the central region (MB).
2. Arrangement according to claim 1, - in which the contact wire (FD) contacts the contact strip (SL) on a first side in a back and forth movement, - in which the central magnetic field sensor (SEN) is arranged on a second side of the contact strip (SL) opposite the first side, and / or - in which the first magnetic field sensor (SEN1) is arranged on a second side of the contact strip (SL) opposite the first side, and / or - in which the second magnetic field sensor (SEN2) is arranged on a second side of the contact strip (SL) opposite the first side.
3. Arrangement according to one of the preceding claims, in which the contact strip (SL) is connected to a contact strip holder and at least one of the magnetic field sensors ( SEN, SEN1 , SEN2 ) is attached to the contact strip holder.
4. Arrangement according to one of the preceding claims, in which the contact wire (FD) and the contact strip (SL) are aligned substantially perpendicular to one another in the contact area in order to form a system geometry.
5. Arrangement according to claim 4, wherein the system geometry arranges the first and second magnetic fields (B1,B2) in respective parallel planes which are orthogonal to the plane of the central magnetic field (B), so that the magnetic fields (B0,B1,B2) are decoupled from each other via their spacing and via the orthogonality for the magnetic field measurement.
6. Method for determining the wear of a contact strip (SL) of a rail vehicle pantograph, - in which a contact strip (SL) is divided in its length into a middle area (MB), into a first partial area (TB1) and divided into a second sub-area (TB2), the middle area (MB) being arranged between the two sub-areas (TB1, TB2), - in which a contact wire (FD) contacts the contact strip (SL) in order to feed a contact wire current (I) into the contact strip (SL), which is divided there into a first partial current (II) flowing in the first partial area (TB1) and a second partial current (II2) flowing in the second partial area (TB2), - where a central magnetic field sensor (SEN) is used to monitor the middle area (MB) in order to to measure the central magnetic field (B) caused by the contact wire current (I) at a distance, whereby the distance includes a thickness of the contact strip (SL) in the central area (MB), - in which a first magnetic field sensor (SEN1) is used to monitor the first partial area (TB1) in order to measure a first magnetic field (B1) caused by the first partial current (II) at a distance, wherein the distance includes a thickness of the contact strip (SL) in the first partial area (TB1), - in which a second magnetic field sensor (SEN2) is used to monitor the second partial area (TB2) in order to measure a second magnetic field (B2) caused by the second partial current (12) at a distance, wherein the distance includes a thickness of the contact strip (SL) in the second partial area (TB2), - in which, during calibration, the magnetic field sensors (SEN, SEN1, SEN2) are arranged on an unused contact strip (SL) for area monitoring in such a way that electrical signals (S, S1, S2) formed from the measured magnetic fields (B, B1, B2) add up to a total signal value of zero, - in which, in a subsequently used contact strip, electrical signals (S, S1, S2) formed from the measured magnetic fields (B, B1, B2) are summed up to form a total signal value not equal to zero, which is fed to a vehicle diagnostic device (FDV) which, based thereon and in comparison to the calibration, determines a current thickness of the used contact strip (SL) in the central region (MB).
7. Method according to claim 6, wherein a system geometry is formed by the contact wire (FD) which is aligned substantially perpendicular to the contact strip (SL) in the contact area with the contact strip (SL).
8. Method according to claim 7, wherein the system geometry decouples the first and second magnetic fields (B1, B2), which are arranged in respective parallel planes and which are both orthogonal to the plane of the central magnetic field (B), from one another via their distance and via the orthogonality for the magnetic field measurement.
9. Method according to one of claims 6 to 8, wherein the sum of the signals (S,S1,S2) of the magnetic field sensors ( SEN, SEN1 , SEN2 ) are processed based on their mean values, preferably at specified time intervals.
10. Method according to one of claims 6 to 9, wherein the calibration is carried out each time an unused contact strip is installed on the rail vehicle and / or wherein the calibration is carried out at room temperature of the pantograph.