MEASURING DEVICE FOR A RAIL VEHICLE AND METHOD FOR DETERMINING AT LEAST ONE CHARACTERISTIC VALUE ON THE VEHICLE'S SIDE

Description

[0001] The invention relates to a measuring device for a rail vehicle for determining at least one characteristic value for the grip of a track during travel and furthermore to a method for determining such a characteristic value.

[0002] The grip of a track, also known as adhesion, refers to the friction between the track rail and the wheel of the rail vehicle. This friction enables the rail vehicle to accelerate or brake. If there is insufficient grip or adhesion, the wheels will spin during acceleration and slip, lock, or slide during braking. This results in a loss of traction or braking power for the rail vehicle and causes or increases wear and tear on the wheel and rail. Wheel spin or locking during acceleration and braking is monitored and prevented by systems such as wheel slide protection systems (WSPs). However, energy loss before wheel slippage or locking is not prevented if the driver's behavior does not take adhesion into account.The WSP systems therefore only react, but do not prevent.

[0003] The grip of the track can be influenced by various factors besides the material properties, such as weather-related moisture or icing, slippery leaves on the tracks (for example, in autumn), the condition of the tracks or wheels, and also the weight of the rail vehicle. Therefore, it is important to monitor and consider the changing grip to ensure safe and efficient train operations.

[0004] In manual train operation, where a train driver or other personnel have full control of the train, they must be aware of the track's grip and control the train accordingly. If the grip is low, for example due to wet or icy weather conditions, the driver may reduce speed and increase the braking distance to prevent wheel slippage. The assessment of track grip is based on the driver's experience and visual impression.

[0005] In future rail transport, the level of automation will increase, meaning that train drivers and other personnel will have less or no responsibility or influence over the control of the rail vehicle. Even at a level of automation (GOA) of 2 and above, where, for example, an ATO (Automatic Train Operation) system is used for automatic control of the rail vehicle, acceleration and braking are carried out by the ATO system and only under the supervision of the train driver. For the ATO system, and generally for an automated rail vehicle, it is important to consider a characteristic value for the grip of the track in order to calculate an energy-efficient driving curve, adhere to the timetable, and minimize wear on wheels and rails.

[0006] Even in established railway standards, various sources are identified where a characteristic value for the current grip of the track can be obtained. These are as follows: Such a characteristic value can be transmitted via a radio interface to a trackside ATO (Automatic Train Operation) equipment on the train.

[0007] A characteristic value for grip can come from a train control system such as ETCS (European Train Control System) via a changed speed requirement, which is justified by low grip.

[0008] A grip rating can be manually entered by the train driver on the rail vehicle, for example via the ETCS control panel or via separate hardware buttons inside the driver's cab.

[0009] The first two adhesion data sources originate from trackside information (from the Traffic Management System or trackside ETCS equipment – ​​ETCS-TS), which can only provide up-to-date information if the entire track is continuously monitored for adhesion. This could be achieved via a frequently used route. However, for example, the first train after a storm in a rural area would only have access to the current adhesion data too late because the track has not yet received the adhesion information. Regarding the third point, adhesion input by the train driver is only possible if the driver is on board. This is not the case with higher levels of automation. If the grip value in the ATO (Automatic Traction Equipment) is higher than the actual grip, the train generates more traction force than necessary, resulting in energy losses.If, on the other hand, the input adhesion parameter is lower than the actual grip of the track and the ATO system follows a rather conservative approach, the train will have difficulty adhering to the timetable because it will accelerate and brake too cautiously. Therefore, the most accurate possible parameter for the current grip of the track is desirable.

[0010] This applies particularly to automation levels (GOA) 3 and 4, where the ATO control system has full responsibility for controlling the train, and at GOA 4, there is no personnel on board. At these automation levels, manual input of a characteristic value for the track grip by the train driver is therefore no longer possible, yet a precise characteristic value for the grip is still desirable.

[0011] While there are well-known systems for rail vehicles designed to prevent wheel slippage, such as the aforementioned WSP (Wheel Slide Protection System), these systems do not use the road surface grip as a metric for optimizing travel. Instead, they focus on the wheel slippage or locking of the rail vehicle's drive wheels. Such systems are described, for example, in "MANAGING LOW ADHESION," AWG Manual, 6th edition, January 2018.

[0012] WO 01 / 71315 Al describes a device for measuring friction and CH 653297 A5 a track measuring car.

[0013] The invention is therefore based on the objective of providing a measuring device and a method of the type mentioned at the outset, by which a more reliable characteristic value for the grip of the track of a rail vehicle can be determined.

[0014] According to the invention, this problem is solved by a measuring device according to claim 1 and a method according to claim 11. The solution according to the invention has the advantage that the characteristic value for the grip is determined on-site at the rail vehicle and can be updated at any time. This allows even rapidly changing grip conditions of the track during travel, for example due to black ice or sudden heavy rain, to be determined and taken into account immediately.

[0015] In the measuring device according to the invention, the measuring wheel is used to establish direct contact with the track. The measuring wheel is held by means of the wheel suspension and attached to the rail vehicle in such a way that the articulated connection of the measuring wheel decouples it from the rail vehicle. In this way, the pressure force can be applied by means of the pressure medium, pressing the measuring wheel against the track. To generate at least a slight deceleration of the measuring wheel on the track, a braking device is provided, which generates the braking torque acting on the measuring wheel during the measurement. Finally, according to the invention, the sensor device acquires a measured value representative of the rotation of the measuring wheel, from which the characteristic value for the grip of the track can then be determined in comparison to the speed of the rail vehicle or a value representative thereof.

[0016] The solution according to the invention can be further developed by advantageous embodiments, which are described below.

[0017] The measuring device according to the invention has at least one computing device which determines the characteristic value for grip, taking into account the measured value of the sensor device.

[0018] This has the advantage that the characteristic value for grip is determined directly by the measuring device via the computing unit, and not by an external unit, such as one located in the vehicle's computer. Furthermore, the computing unit can be configured to determine the characteristic value taking into account the speed of the rail vehicle during the measurement. This has the advantage of making the characteristic value particularly easy to determine, since the speed of the rail vehicle is usually already known.

[0019] To ensure simple data transmission between the measuring device and the rail vehicle, the measuring device can have at least one vehicle interface with which the measuring device can be connected to the rail vehicle according to the invention with an ATO device and optionally a vehicle bus of the rail vehicle.

[0020] In a further advantageous embodiment, the measuring wheel can be made of a material, particularly a synthetic material, that has a higher coefficient of friction than the wheels of the rail vehicle. This has the advantage of enabling a reliable measurement because the measuring wheel has a higher grip on the track than the steel wheel of the rail vehicle. Naturally, the entire measuring wheel, or a large part of it, can also be made of this material. This has the advantage that the measuring wheel can deform more during the measurement than the steel wheel of the rail vehicle. This deformation causes a measurable difference in rotation, from which a characteristic value for the grip can be determined. The material can be, for example, rubber or a rubber-like material.

[0021] To achieve a simple design for the measuring device, the pressure medium can be engaged with the wheel suspension and, in particular, be designed as a servo motor. Alternatively, a large weight could, for example, apply downward pressure to the wheel suspension at a suitable point, or a spring-damper unit could be used to press the axis of rotation of the measuring wheel downwards via the wheel suspension. The servo motor design, which is located, for example, in the joint of the wheel suspension, has the advantage that it can generate the contact force of the measuring wheel and also detect wear-related changes in the angle of rotation of the wheel suspension.

[0022] In a further advantageous embodiment, the braking device can be attached to the wheel suspension and comprise at least one brake pad. This has the advantage of allowing for a simple design. The brake pad, for example, can be supported by the wheel suspension and press against the measuring wheel to generate the braking torque.

[0023] To limit wear on the measuring wheel, the measuring device can include at least one activation device designed to move the measuring wheel from a rest position without contact with the track to a measuring position with contact. Such an activation device can be implemented, for example, by a servo motor, which can also perform other tasks, such as applying the contact force as mentioned above. Other designs, such as a pneumatic cylinder, are of course also possible. Since determining the grip value may not be required continuously, this design can significantly reduce wear on the measuring wheel.

[0024] Furthermore, the measuring device, in particular the braking device and the pressure medium, can be designed such that the measuring wheel is braked during the measurement, but not completely blocked. This has the advantage that the recorded measurement value is highly reliable.

[0025] The invention further relates to a rail vehicle which, according to the invention, comprises a measuring device according to one of the aforementioned embodiments.

[0026] In an advantageous embodiment of the rail vehicle according to the invention, which has at least one ATO device configured for automated control of the rail vehicle, the ATO device can be configured to control the rail vehicle taking into account the characteristic value. This has the advantage that the ATO device can thereby control the rail vehicle particularly effectively and is still adapted to the current grip of the track.

[0027] According to the invention, a value for the speed of the rail vehicle during the measurement is taken into account when determining the characteristic value. This has the advantage that the characteristic value can be calculated in a simple way and the speed of the rail vehicle is usually known and does not have to be determined first.

[0028] Furthermore, a value for the coefficient of friction of the measuring wheel-track connection and a value for the relative measuring wheel slip are determined, and these values ​​are taken into account when determining the characteristic value by comparing them with known values ​​for known grip properties. This has the advantage that the characteristic value for grip can be determined reliably.

[0029] The invention will now be explained with reference to the accompanying drawings and the exemplary embodiments shown therein.

[0030] They show: Figure 1 is a schematic representation of a rail vehicle according to the invention with a measuring device according to the invention; Figure 2 is an enlarged schematic representation of the measuring device according to the invention. Figure 1 Figure 3 shows a schematic representation of a µ-λ diagram, which is measured from the measuring device. Figures 1 and 2 is used.

[0031] The invention is described below with reference to the exemplary embodiment in the Figures 1 to 3 explained.

[0032] A rail vehicle 1 travels in a direction 2 on a track 3, as described in Figure 1 The rail vehicle 1 is, for example, a locomotive, a high-speed train, a suburban train, a subway, a tram, or similar. The track 3 is constructed in the usual way from parallel steel rails, on which the rail vehicle 1 travels with its wheels 4.

[0033] The wheels 4 of rail vehicle 1 are made of steel in the usual way, as are the rails of track 3. The connection between rail vehicle 1 and track 3 is therefore a steel-to-steel or metal-to-metal contact between wheels 4 and track 3. This connection between rail vehicle 1 and track 3 has become historically established, even though its frictional behavior is inferior to other material combinations in the contact report.

[0034] Additionally, the frictional behavior in the contact area between rail vehicle 1 and track 3 is also affected by external influences, such as weather-related moisture or ice. This alters the grip of the track 3, sometimes also referred to as adhesion. This grip of the track 3 influences the behavior of rail vehicle 1 during acceleration and braking. With low grip on the track 3, the wheels 4 can slip during acceleration and lock up during braking. This results in sliding friction, the coefficient of which is lower than that of static friction, which prevails without slippage.

[0035] It is advantageous to avoid wheel spin or locking, as otherwise there will be less traction or less braking of the rail vehicle 1.

[0036] In current technology, a characteristic value for the grip of the track 3 is entered into the vehicle control system by a train driver, who determines this value based on their impression of the track and their experience. Future rail vehicles 1 will increasingly be operated autonomously, i.e., without a train driver.

[0037] The rail vehicle 1 in the exemplary embodiment shown in the figures has no driver, but is equipped with an ATO device 5 that automatically controls the rail vehicle 1. The rail vehicle 1 according to the invention comprises a measuring device 6 according to the invention, by which the characteristic value for the grip of the track 3 is automatically determined.

[0038] The measuring device 6, which is in Figure 2The enlarged image shows a measuring wheel 7, a wheel suspension 8, a pressure medium 10, a braking device 11 and a sensor device 9.

[0039] The measuring wheel 7 is made, at least on its circumference, of a synthetic rubber-like material whose coefficient of friction is higher than that of the wheels 4. During a measurement of the measuring device 6, the measuring wheel 7 contacts the rail of the track 3 on its circumference. The measuring wheel 7 is connected to the wheel suspension 8 at its axis of rotation 12.

[0040] The wheel suspension 8 comprises a mounting unit 13, with which it is essentially rigidly connected to the underbody 14 of the rail vehicle 1. The connection to the rail vehicle 1 can be implemented in the usual manner as a screw connection. Furthermore, the wheel suspension comprises a lever unit 15, which is connected to the mounting unit 13 in a pivot joint 16. On the other side, the lever unit 15 is connected to the measuring wheel 7 in the region of the pivot axis 12.

[0041] The pressure medium 10 is arranged at the pivot joint 16 of the wheel suspension and, in the exemplary embodiment, in Figure 2The servomotor is designed as a servomotor that exerts a torque Mp on the lever unit 15. The servomotor also simultaneously functions as an activation device, moving the measuring wheel from a rest position without contact to the track to a measuring position with contact to the track during the measurement. This reduces the wear of the measuring wheel 7.

[0042] The braking device 11 is attached to the lever unit 15 and exerts a substantially constant braking torque T b on the measuring wheel 7 during the measurement.

[0043] The measurement with the measuring device 6 according to the invention takes place during the movement of the rail vehicle 1 as follows: The measuring wheel 7 contacts the track 3 and rotates due to the friction between the measuring wheel 7 and the track 3. The pressure medium 10 generates a substantially constant contact force Fz of the measuring wheel 7 against the track 3 via the lever unit 15 with lever length d. In the exemplary embodiment, the sensor device 9 comprises Figure 2 at least one rotation sensor, here a displacement pulse generator (not shown), which determines the rotation of the measuring wheel 7 about its axis of rotation 12. The rotation, determined very precisely by the sensor device 9, allows for the detection of any deceleration of the measuring wheel 7, even if it is very slight. This allows, for example, a comparison with an unbraked wheel, such as wheel 4 of the rail vehicle 1, or with the speed of the rail vehicle 1.

[0044] The measuring device 6 also includes a computing device 17. This device has at least one vehicle interface (not shown) that is connected to the ATO device 5. The computing device 17 receives the speed v of the rail vehicle 1, which is available to the ATO device 5, via this interface. Alternatively, the computing device 17 could also receive the speed v via an interface to the vehicle bus of the rail vehicle 1, through which the speed v is also available.

[0045] To facilitate the calculation of the coefficient of friction µ for the connection between the measuring wheel 7 and the travel path 3, the device 6 according to the invention induces a temporary braking of the measuring wheel 7 by the braking torque Tb. According to the invention, the braking torque Tb generated by the braking device 11 is set such that only a temporary, slight braking of the measuring wheel 7 is produced, without the measuring wheel 7 completely locking up.

[0046] Using the measured values ​​of the sensor device 9 and the other known parameters of the measuring device 6, the following can be calculated according to known relationships: I w ω ˙ = r F x − T b F x = F z . μ λ

[0047] These are: I w : Moment of inertia of the measuring wheel 7 r : Radius of measuring wheel 7 ω: Angular velocity of measuring wheel 7 F x : Frictional force of the measuring wheel 7 F z : Contact force of the measuring wheel 7 v : Speed ​​of the rail vehicle 1 T b: Braking torque of measuring wheel 7 µ: Wheel-rail coefficient of friction λ : relative slip of the measuring wheel 7

[0048] Since the measuring wheel 7 is relatively small, the moment of inertia IW can be neglected. Furthermore, the measurement of the measuring device 6 is carried out at a constant speed of the rail vehicle 1, so that the measuring device 6 has stabilized and ω̇ can be assumed to be 0 ( ω̇ ~ 0). This results in: μ λ = T b F z . r

[0049] The computing device 17 can thus determine a value for estimating the coefficient of friction µ(λ) of the measuring wheel 7 for the travel distance 3. Additionally, the following formula applies to the slip of the measuring wheel 7: λ = v − r . ω v

[0050] The values ​​for A and µ determined in this way can be entered into the Figure 3 The diagram shown can be used to create an intersection point 18.

[0051] In the diagram in Figure 3Several curves are plotted. These curves 19 are known during the measurement of the measuring device 6, in particular stored in the computing device 17. The curves 19 were determined beforehand, for example in the laboratory or in other tests. The curves 19 show the behavior of the connection between the measuring wheel 7 and the track 3 under different weather conditions or influences. For example, curve A represents a dry track 3, curve B a wet track, curve C an oily track, and curve D an icy track. The computing device 17 now determines which of the curves 19 is closest to the intersection point 18, and then the condition corresponding to the nearest curve 19 is defined as the characteristic value for the grip of the track 3. Thus, for example, the curve A, B, C, D that is closest to the intersection point 18 is taken as the characteristic value.

[0052] The characteristic value for the grip of the track 3, determined in this way, is then transmitted to the ATO device 5, which takes this characteristic value into account when calculating the driving and braking curves for the rail vehicle 1. This characteristic value, determined according to the invention, for the current grip of the track 3 prevailing at the rail vehicle 1 can be updated at any time and thus adapts quickly to changing grip conditions. The ATO device 5, which operates with this characteristic value, can therefore control the rail vehicle 1 without slippage occurring.

[0053] The characteristic value determined according to the invention can, of course, also be transmitted by the rail vehicle 1 to a control center or other higher-level authority. Further processing can then take place there. For example, the characteristic value can be transmitted to other rail vehicles that are not equipped with the measuring device 6 according to the invention. Furthermore, many characteristic values ​​for different locations can be stored over time, so that a map of the rail network is created on which the characteristic values ​​can be read.

[0054] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

1. Measuring device (6) for a rail vehicle (1) for determining at least one characteristic value, on the vehicle side, for a road grip of a route (3) during the journey, with at least one measuring wheel (7) which is embodied to make contact with the route (3), with at least one wheel suspension (8) connected to the measuring wheel (7) in its axis of rotation (12), said wheel suspension (8) being embodied to fasten to the rail vehicle (1) and to establish an articulated connection between the rail vehicle (1) and the measuring wheel (7), with at least one compression means (10), which is embodied to generate a substantially constant pressing force of the measuring wheel (7) against the route (3) during the measurement, with at least one brake assembly (11) which is embodied to generate a substantially constant brake torque acting on the measuring wheel (7) during the measurement, and with at least one sensor device (9) which is embodied to detect at least one measured value which is representative of the rotation of the measuring wheel (7) relative to the wheel suspension (8), wherein the measuring device (6) has at least one vehicle interface, with which the measuring device (6) can be connected to an ATO device (5) of the rail vehicle (1), so that the ATO device (5) can control the rail vehicle (1) by taking into account the characteristic value, and the measuring device (6) has at least one computing device (17), which determines the characteristic value for the road grip by taking into account the measured value of the sensor device (9) and the computing device (17) is embodied to determine the characteristic value by taking into account a value for the speed of the rail vehicle (1) during the measurement and in each case to determine a value for a friction coefficient of the measuring wheel-routes-connection and a value of a relative measuring wheel slip and to take these values into account during the determination of the characteristic value such that they are compared with known values for known road grips.

2. Measuring device (6) according to claim 1, characterised in that the measuring device (6) is embodied to be connectable to a vehicle bus of the rail vehicle (1) by means of the vehicle interface.

3. Measuring device (6) according to one of the afore-cited claims, characterised in that the circumference of the measuring wheel (7) consists of a material, in particular a synthetic material, which has a higher coefficient of friction than the wheels (4) of the rail vehicle (1).

4. Measuring device (6) according to claim 3, characterised in that the material is rubber or a rubber-type material.

5. Measuring device (6) according to one of the afore-cited claims, characterised in that the compression means (10) is engaged with the wheel suspension (8) and is embodied in particular as a servomotor.

6. Measuring device (6) according to one of the afore-cited claims, characterised in that the brake device (11) is fastened to the wheel suspension (8) and comprises at least one brake pad.

7. Measuring device (6) according to one of the afore-cited claims, characterised in that the measuring device (6) has at least one activation device, which is embodied to move the measuring wheel (7) from a rest position without contact with the route (3) into a measuring position with contact with the route (3).

8. Measuring device (6) according to one of the afore-cited claims, characterised in that the measuring device (6), in particular the brake device (11) and the compression means (10), is embodied such that during the measurement the measuring wheel (7) is braked but is not completely blocked.

9. Rail vehicle (1), characterised in that the rail vehicle (1) comprises a measuring device (6) according to one of the afore-cited claims.

10. Rail vehicle (1) according to claim 9, wherein the rail vehicle (1) has at least one ATO device (5), which is embodied to automatically control the rail vehicle (1), characterised in that the ATO device (5) is embodied to control the rail vehicle (1) by taking into account the characteristic value.

11. Method for determining at least one characteristic value, on the vehicle side, for a road grip of a route (3) of the rail vehicle during the journey of a rail vehicle (1), in which at least one measuring wheel (7) of a measuring device (6) is brought into contact with the route (3), in which by means of the measuring device (6) a substantially constant pressing force of the measuring wheel (7) against the route (3) is generated, in which by means of the measuring device (6) a substantially constant brake torque acting on the measuring wheel (7) is generated and in which by means of a sensor device (9) at least one measured value which is representative of the rotation of the measuring wheel (7) is determined, wherein the characteristic value is determined by taking into account the measured value, and the measuring device (6) comprises a wheel suspension (8), which is connected to the measuring wheel (7) in an axis of rotation, which is embodied to fasten to the rail vehicle (1) and to establish a hinged connection between the rail vehicle (1) and the measuring wheel (7), wherein the measuring device (6) is connected to an ATO device (5) of the rail vehicle (1) by means of a vehicle interface so that the ATO device (5) can control the rail vehicle (1) by taking into account the characteristic value, the measuring device (6) uses a computing device (17) to determine the characteristic value of the road grip by taking into account the measured value of the sensor device (9) and during the determination of the characteristic value a value for the speed of the rail vehicle (1) is taken into account during the measurement, and in each case a value for a coefficient of friction of the measuring wheel-routes-connection and a value for a relative measuring wheel slip are determined and these values are taken into account during the determination of the characteristic value such that they are compared with known values for known road grips.