Measuring device for a rail vehicle and method for determining at least one characteristic value on the vehicle side

Abstract

The invention relates to a measuring device (6) for a rail vehicle (1) for determining at least one characteristic value for the grip of a track (3) during travel, comprising at least one measuring wheel (7) designed to contact the track (3), at least one wheel suspension (8) connected to the measuring wheel (7) in its axis of rotation (12), designed for attachment to the rail vehicle (1) and for establishing an articulated connection between the rail vehicle (1) and the measuring wheel (7), at least one pressure means (10) designed to generate a substantially constant contact force of the measuring wheel (7) against the track (3) during the measurement, at least one braking device (11) designed to generate a substantially constant braking torque acting on the measuring wheel (7) during the measurement, and at least one sensor device (9).which is designed to capture at least one measured value representative of the rotation of the measuring wheel (7) relative to the wheel suspension (8). The measuring device (6) according to the invention has the advantage that it can automatically determine a current characteristic value for the rail vehicle (1). The invention also relates to a method for determining at least one characteristic value for the grip of a track (3) on the vehicle side.

Description

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

[0002] The grip of a track, also known as adhesion, refers to the friction between a rail on the track 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 skid, lock, or slide during braking. This causes the rail vehicle to lose traction or braking power and causes or increases wear or damage to the wheel and rail. Wheel spin or lock during acceleration and braking is monitored and prevented by systems such as wheel slide protection (WSP) systems. However, the energy loss before the wheels slide or lock 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] In addition to the material properties, the skid resistance of the track can be influenced by various factors, such as weather-related moisture or ice, slippery leaves on the tracks (e.g., in autumn), the condition of the track or wheels, and even the weight of the rail vehicle. Therefore, it is important to monitor and consider changing skid resistance to ensure safe and efficient train service.

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

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

[0006] The well-known railway standardization also lists various sources from which a characteristic value for the current skid resistance of the track can be obtained. These are as follows: Such a characteristic value can be transmitted to the rail vehicle via an interface for a radio connection to trackside ATO equipment.

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

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

[0009] The first two adhesion sources come from trackside information (from the traffic management system or from the trackside ETCS equipment - ETCS-TS), which can only provide up-to-date information if the entire line is constantly monitored for adhesion. This could be done on a frequently used line. However, for example, the first vehicle to arrive after a storm in a rural region would only have access to the current adhesion level too late because the line does not yet have the adhesion information. Regarding the third point, the driver can only input adhesion information if the driver is on board. This is not the case with higher levels of automation. If the grip value in the ATO is higher than the actual grip level, the vehicle generates more tractive force than necessary, resulting in energy losses.On the other hand, if the entered adhesion index is lower than the current grip level of the track and the ATO system follows a more conservative approach, the rail vehicle will have difficulty adhering to the schedule due to overly cautious acceleration and braking. Therefore, a value as accurate as possible for the current grip level of the rail vehicle's track is desirable.

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

[0011] While there are also known systems for rail vehicles designed to prevent slippage, such as the aforementioned WSP (Wheel Slide Protection System), these systems do not determine the grip of the track as a value for optimizing the ride, but rather the 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] The invention is therefore based on the object of providing a measuring device and a method of the type mentioned at the outset, by means of which a more reliable characteristic value for the grip of the track of a rail vehicle can be determined.

[0013] According to the invention, this object is achieved by a measuring device for a rail vehicle for determining at least one characteristic value for a grip of a route during travel, with at least one measuring wheel designed to make contact with the track, with at least one wheel suspension connected to the measuring wheel in its axis of rotation, which wheel suspension is designed to be fastened to the rail vehicle and to produce an articulated connection between the rail vehicle and the measuring wheel, with at least one pressure medium designed to generate a substantially constant pressure force of the measuring wheel against the track during the measurement, with at least one braking device designed to generate a substantially constant braking torque acting on the measuring wheel during the measurement, and with at least one sensor device designed to detect at least one measured value representative of the rotation of the measuring wheel relative to the wheel suspension.

[0014] Furthermore, this object is achieved by a method according to the invention for determining at least one characteristic value for a grip of a track of the rail vehicle during the travel of a rail vehicle, in which at least one measuring wheel of a measuring device is brought into contact with the track, in which a substantially constant pressure force of the measuring wheel against the track is generated by means of the measuring device, in which a substantially constant braking torque acting on the measuring wheel is generated by means of the measuring device and in which at least one measured value representative of the rotation of the measuring wheel is determined by means of a sensor device, wherein the characteristic value is determined taking into account the measured value and the measuring device comprises a wheel suspension which is connected to the measuring wheel in an axis of rotation, which is designed for fastening to the rail vehicle and for establishing an articulated connection between the rail vehicle and the measuring wheel.

[0015] The inventive solution has the advantage that the characteristic value for skid resistance is determined on-site on the rail vehicle and can be updated at any time. This allows even rapidly changing skid resistance on the track during travel, for example, due to black ice or sudden heavy rain, to be immediately determined and taken into account.

[0016] 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 the wheel suspension and attached to the rail vehicle in such a way that the articulated connection of the measuring wheel creates a decoupling from the rail vehicle. The pressure medium can thus be used to apply the pressure force and press the measuring wheel against the track. In order to at least slightly decelerate 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 records a measured value representative of the rotation of the measuring wheel, which can then be used to determine the characteristic value for the grip of the track in comparison to the speed of the rail vehicle or a value representative thereof.

[0017] The solution according to the invention can be further developed by advantageous embodiments which are described below.

[0018] The measuring device can thus have at least one computing device that determines the characteristic value for the grip, taking into account the measured value from the sensor device. This has the advantage that the computing device determines the characteristic value for the grip directly from the measuring device and not by a unit external to the measuring device, for example, located in the vehicle computer. Furthermore, the computing unit can be designed to determine the characteristic value, taking into account a value for the speed of the rail vehicle during the measurement. This has the advantage that the characteristic value can be determined particularly easily, since the speed of the rail vehicle is usually already known.

[0019] In order 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, in particular to an ATO device and / or a vehicle bus of the rail vehicle.

[0020] In an advantageous development, the measuring wheel can be made of a material on the circumference, in particular a synthetic material, which has a higher coefficient of friction than the wheels of the rail vehicle. This has the advantage of resulting in reliable measurements because the measuring wheel has a higher grip on the track than the steel wheel of the rail vehicle. Of course, the entire measuring wheel or a large part of the measuring wheel 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, for example, be rubber or a rubber-like material.

[0021] To achieve a simple measuring device design, the pressure medium can be engaged with the wheel suspension and, in particular, can be designed as a servomotor. Alternatively to the servomotor, a large weight could be applied to the wheel suspension at a suitable location and press it downwards, or a spring-damper unit could be used to press the axis of rotation of the measuring wheel downwards via the wheel suspension. The servomotor design, which is arranged, for example, in the joint of the wheel suspension, has the advantage that it can be used to generate the contact pressure of the measuring wheel and, in addition, to detect a wear-related angular change in the pivot point 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 a simple construction. The brake pad can, for example, be supported on 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 have at least one activation device designed to move the measuring wheel from a rest position without contact with the travel path to a measuring position with contact with the travel path. Such an activation device can be implemented, for example, by a servo motor, which can also perform other tasks at the same time, such as applying the contact pressure as already mentioned above. Other configurations, such as a pneumatic cylinder, are of course also possible. Since the determination of the characteristic value for the grip may not be required permanently, this configuration 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 measured value is highly meaningful.

[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 the characteristic value into account. This has the advantage that the ATO device can thereby control the rail vehicle particularly effectively while still being adapted to the current grip of the route.

[0027] In an advantageous embodiment of the method according to the invention, a value for the speed of the rail vehicle during the measurement can be taken into account when determining the characteristic value. This has the advantage that the characteristic value can be easily calculated, and the speed of the rail vehicle is usually known at this time and does not need to be determined first.

[0028] Furthermore, a value for the friction coefficient of the measuring wheel-track connection and a value for the relative measuring wheel slip can be determined. These values ​​can be 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 reliably determined.

[0029] In the following, the invention is explained with reference to the accompanying drawings and the exemplary embodiments shown therein.

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

[0031] In the following, the invention will be described 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 route 3 as shown in Figure 1The rail vehicle 1 is, for example, a locomotive, a high-speed train, a commuter train, a subway, a tram, or the like. The track 3 is typically constructed from parallel steel rails on which the rail vehicle 1 runs with its wheels 4.

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

[0034] In addition, the friction 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 changes the grip of track 3, which is sometimes also referred to as adhesion. This grip of track 3 influences the behavior of rail vehicle 1 during acceleration and deceleration. If the grip of track 3 is low, wheels 4 can spin during acceleration and lock during deceleration. This results in sliding friction whose coefficient of friction is lower than that of static friction, which prevails without slippage.

[0035] It is advantageous to avoid spinning or locking of the wheels 4, since otherwise less traction or less braking of the rail vehicle 1 occurs.

[0036] In the current state of the art, a characteristic value for the grip of the track 3 is input into the vehicle control system by a train driver, which the driver determines based on his impression of the track and his 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 illustrated in the figures does not have a 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 skid resistance of the track 3 is automatically determined.

[0038] The measuring device 6, which is Figure 2is shown enlarged, comprises 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 the coefficient of friction of the wheels 4. During a measurement by 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 in its axis of rotation 12.

[0040] The wheel suspension 8 comprises an attachment 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 way as a screw connection. Furthermore, the wheel suspension comprises a lever unit 15, which is connected to the attachment unit 13 via a pivot joint 16. On the other side, the lever unit 15 is connected to the measuring wheel 7 in the region of the rotation axis 12.

[0041] The pressure medium 10 is arranged on the swivel joint 16 of the wheel suspension and in the exemplary embodiment in Figure 2It is designed as a servomotor that exerts a torque M p on the lever unit 15. The servomotor also functions as an activation device, designed to move the measuring wheel from a rest position without contact with the travel path to a measuring position with contact with the travel path during the measurement. This reduces wear on 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 travel 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 via the lever unit 15 with the lever length d a substantially constant contact force F z of the measuring wheel 7 against the track 3. The sensor device 9 comprises in the exemplary embodiment in Figure 2 at least one rotation sensor, here a displacement encoder (not shown), which determines the rotation of the measuring wheel 7 about its rotational axis 12. The rotation, which is determined very precisely by the sensor device 9, can be used to detect any deceleration of the measuring wheel 7, even if it is very slight. For example, a comparison can be made with a non-braked 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 has at least one vehicle interface (not shown) connected to the ATO device 5. Via this interface, the computing device 17 receives the speed v of the rail vehicle 1, which is available to the ATO device 5. Alternatively, the computing device 17 could also receive the speed v via an interface to the vehicle bus of the rail vehicle 1, via which the speed v is also available.

[0045] In order to more easily calculate a coefficient of friction µ for the connection of the measuring wheel 7 to the track 3, the device 6 according to the invention causes a temporary braking of the measuring wheel 7 by the braking torque T b. The braking torque T b generated by the braking device 11 is adjusted according to the invention such that only a temporary slight braking of the measuring wheel 7 is generated, without the measuring wheel 7 completely blocking.

[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 include: IW : Moment of inertia of the measuring wheel 7 r : Radius of the measuring wheel 7 ω: Angular velocity of the measuring wheel 7 F x : Friction force of the measuring wheel 7 F z : Pressure force of the measuring wheel 7 v : Speed ​​of the rail vehicle 1 T b: Braking torque of the measuring wheel 7 µ: Wheel-rail friction coefficient λ : relative slip of the measuring wheel 7

[0048] Since the measuring wheel 7 is relatively small, the moment of inertia I w 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 gives: μ λ = T b F z . r

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

[0050] The values ​​for λ and µ thus determined can be entered in Figure 3 shown diagram can be used to obtain an intersection point 18.

[0051] In the diagram in Figure 3several curves are drawn. These curves 19 are known during the measurement of the measuring device 6, in particular they are stored in the computing device 17. The curves 19 were determined in advance, for example in the laboratory or during 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 of the nearest curve 19 is set as the characteristic value for the grip of the track 3. For example, the curve A, B, C, D that is closest to the intersection point 18 is assumed as the characteristic value.

[0052] The thus determined characteristic value for the grip of track 3 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 grip of track 3 currently prevailing on the rail vehicle 1 can be updated at any time and thus quickly adapts to changing grip conditions. The ATO device 5, operating with this characteristic value, can thus control the rail vehicle 1 without slippage occurring.

[0053] The characteristic value determined according to the invention can, of course, also be forwarded from the rail vehicle 1 to a control center or another higher-level location. Further processing can take place there. For example, the characteristic value can be forwarded 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, creating a map of the rail network 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. A measuring device (6) for a rail vehicle (1) for determining at least one characteristic value for the grip of a track (3) during travel, comprising at least one measuring wheel (7) designed to make contact with the track (3), at least one wheel suspension (8) connected to the measuring wheel (7) in its axis of rotation (12), which is designed to be fastened to the rail vehicle (1) and to establish an articulated connection between the rail vehicle (1) and the measuring wheel (7), at least one pressure medium (10) designed to generate a substantially constant pressure force of the measuring wheel (7) against the track (3) during the measurement, at least one braking device (11) designed to generate a substantially constant braking torque acting on the measuring wheel (7) during the measurement, and at least one sensor device (9),which is designed to detect at least one measured value representative of the rotation of the measuring wheel (7) relative to the wheel suspension (8).

2. Measuring device (6) according to claim 1, characterized in that the measuring device (6) has at least one computing device (17) which determines the characteristic value for the grip taking into account the measured value of the sensor device (9).

3. Measuring device (6) according to claim 2, characterized in that the computing unit (15) is designed to determine the characteristic value taking into account a value for the speed of the rail vehicle (1) during the measurement.

4. Measuring device (6) according to one of the above claims, characterized in that the measuring device (6) has at least one vehicle interface with which the measuring device (6) is designed to be connectable to the rail vehicle (1), in particular to an ATO device (5) and / or a vehicle bus of the rail vehicle (1).

5. Measuring device (6) according to one of the above claims, characterized in that the measuring wheel (7) consists on the circumference of a material, in particular of a synthetic material, which has a higher coefficient of friction than the wheels (4) of the rail vehicle (1).

6. Measuring device (6) according to claim 5, characterized in that the material is rubber or a rubber-like material.

7. Measuring device (6) according to one of the above claims, characterized in that the pressure medium (10) is in engagement with the wheel suspension (8) and is designed in particular as a servo motor.

8. Measuring device (6) according to one of the above claims, characterized in that the braking device (11) is fastened to the wheel suspension (8) and comprises at least one brake pad.

9. Measuring device (6) according to one of the above claims, characterized in thatthe measuring device (6) has at least one activation device which is designed to move the measuring wheel (7) from a rest position without contact with the travel path (3) into a measuring position with contact with the travel path (3).

10. Measuring device (6) according to one of the above claims, characterized in that the measuring device (6), in particular the braking device (11) and the pressure medium (10), is designed such that the measuring wheel (7) is braked during the measurement, but not completely blocked.

11. Rail vehicle (1), characterized in that the rail vehicle (1) comprises a measuring device (6) according to one of the above claims.

12. Rail vehicle (1) according to claim 11, wherein the rail vehicle (1) has at least one ATO device (5) which is designed for automated control of the rail vehicle (1), characterized in thatthe ATO device (5) is designed to control the rail vehicle (1) taking into account the characteristic value.

13. A method for determining at least one characteristic value for a grip on a track (3) of the rail vehicle during travel of a rail vehicle (1), in which at least one measuring wheel (7) of a measuring device (6) is brought into contact with the track (3), in which a substantially constant pressure force of the measuring wheel (7) against the track (3) is generated by means of the measuring device (6), in which a substantially constant braking torque acting on the measuring wheel (7) is generated by means of the measuring device (6), and in which at least one measured value representative of the rotation of the measuring wheel (7) is determined by means of a sensor device (9), wherein the characteristic value is determined taking into account the measured value and the measuring device (7) comprises a wheel suspension (8) which is connected to the measuring wheel (7) in a rotational axis,which is designed for attachment to the rail vehicle (1) and for establishing an articulated connection between the rail vehicle (1) and the measuring wheel (7).

14. Method according to claim 13, characterized in that When determining the characteristic value, a value for the speed of the rail vehicle (1) during the measurement is taken into account.

15. Method according to claim 14, characterized in that a value for a friction coefficient of the measuring wheel-track connection and a value for a relative measuring wheel slip are determined and these values ​​are taken into account when determining the characteristic value in such a way that they are compared with known values ​​for known grips.

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