Determining the current frictional contact between wheel and rail

Abstract

Method for determining the available frictional contact between at least one wheel (18) of a rail vehicle (10) and a running surface (12) of a rail on which the at least one wheel (18) rolls, comprising the following steps: - Contact at least one magnetic track brake (20) with the running surface (12) of the rail, - Determine at least one contact force (40) between the at least one magnetic track brake (20) on the running surface (12), - Determine at least one tangential force (42) between at least one magnetic track brake (20) and the running surface (12), - Determining the available frictional engagement between wheel (18) and driving surface (12) by processing at least one contact force (40) and at least one tangential force (42), wherein the at least one magnetic track brake (20) is used in such a way that no significant deceleration of the rail vehicle (10) occurs, and wherein the at least one magnetic track brake (20) is used in such a manner, that the procedure for determining the available frictional engagement is separate from a method for generating a braking force for braking the rail vehicle (10) is carried out.

Description

[0001] The present invention relates to a method for determining the current frictional contact between at least one wheel of a rail vehicle and a running surface of a rail on which the wheel rolls. The invention further relates to a magnetic track brake configured to perform such a method, a computer program for performing this method, and a rail vehicle comprising at least one magnetic track brake according to the invention.

[0002] The safety and efficiency of rail vehicle operation depend significantly on the transmissible force (friction) between wheel and rail for propulsion and braking. In current systems, insufficient friction between wheel and rail can only be detected when propulsion or braking forces exceed the transmissible forces between wheel and rail. Consequently, the excess braking or propulsion force causes individual wheels or wheelsets to lock up during braking and to slip during acceleration. This can lead to increased relative movement in the contact between wheel and rail. Since this can cause significant damage to the wheel and rail, it is prevented by vehicle-integrated slip and wheel slip protection systems that intervene in the propulsion and braking control.However, these systems intervene at a point when the required forces can no longer be transmitted. Furthermore, there is a risk that the intervention of anti-slip and anti-skid systems will further reduce the transmissible forces, which has correspondingly negative effects, such as increased braking distances of the rail vehicle. Ultimately, this has negative consequences for the operation of the rail vehicle in terms of safety, economy, and efficiency.

[0003] From DE 10 2011 110 049 B4 a magnetic track braking device for a rail vehicle with a force sensor device for determining the generated braking force is known.

[0004] DE 10 2011 110 053 A1 discloses a brake control device for a braking system of a rail vehicle, which is designed to control at least one magnetic track braking device of the braking system based on track condition data.

[0005] DE 10 2011 113 069 A1 finally shows a possibility for determining frictional adhesion in a rail vehicle.

[0006] Based on this problem, the invention aims to provide a method for determining the currently available traction during the journey of a rail vehicle. Furthermore, the invention aims to provide a corresponding device, a rail vehicle equipped with this device, and a computer program for carrying out this method.

[0007] This task is solved by the independent claims. Advantageous further developments are the subject of the dependent claims.

[0008] Rail vehicles often feature magnetic track brakes, which typically consist of horseshoe-shaped magnetic cores enclosed by coils. When the coils are energized, a magnetic flux is generated, which closes the gap across the rail head. This presses the magnetic track brake, for example, with a section designed for this purpose using sliding shoes, against the rail, and the resulting tangential frictional force acts as a braking force on the rail vehicle. A distinction is made between rigid magnets and articulated magnets arranged in relation to each other, as well as between low-mounted systems, in which the magnetic track brake is held just above the rail surface by springs, and high-mounted systems, in which the magnetic track brake is lowered pneumatically via actuating cylinders.

[0009] To determine the available frictional contact, the magnetic track brake is suitable, as it is a device which can usually be pressed against the running surface of the rail with adjustable contact force, whereby a statement regarding the available frictional contact can be made by analyzing the forces occurring in the frictional contact.

[0010] According to the invention, a method for determining the available frictional contact between at least one wheel of a rail vehicle and a running surface of a rail on which the at least one wheel rolls is provided, wherein at least one magnetic track brake of the rail vehicle is brought into contact with the running surface of the rail, at least one contact force between the at least one magnetic track brake on the running surface is determined, at least one tangential force between the at least one magnetic track brake and the running surface of the rail is determined, and the determination of the available frictional contact is carried out by processing the at least one contact force and the at least one tangential force.

[0011] Preferably, such a rail vehicle has several magnetic track brakes to carry out the procedure described above. More than one magnetic track brake allows for the averaging of several determined values ​​of the available frictional force, thereby enabling the plausibility check of individual frictional force values.

[0012] Preferably, the method is designed such that, by processing at least one determined contact force of the magnetic track brake and a resulting tangential force, in particular a frictional or braking force, an available frictional engagement of at least one wheel of the rail vehicle can be determined. This processing can be carried out by threshold analysis, preferably by characteristic maps, and most preferably by computational models.

[0013] Preferably, the contact force is not only determined but also set to a target value. Setting the contact force then involves determining this force and correcting it to a target value. This has the advantage that the further determination of the available frictional engagement is carried out with a contact force at which the subsequent system behavior of the magnetic track brake is known. The system behavior at this contact force can, for example, be precisely determined in the preliminary development phase, so that, for instance, mechanical deformations are known and can be made available for further processing steps. The magnetic track brake then preferably operates at an operating point characterized by the target value.

[0014] Furthermore, it is also conceivable to have several target values ​​available for setting the contact force. These can, for example, be speed-dependent or dependent on other operating parameters, so that a suitable contact force is always set.

[0015] Preferably, the determination of the at least one contact force and / or the at least one tangential force is carried out by sensors and / or computational models.

[0016] Particularly preferably, the contact force of the magnetic track brake can be determined by measuring the electric current flowing through the coils of the electromagnets to generate the magnetic field of the magnetic track brake. Furthermore, an additional force can preferably be determined at the bearing points of the actuating cylinders, or other suitable locations, by force sensors, in particular load cells, or other suitable sensors, or preferably by measuring the pressure in the actuating cylinders of the magnetic track brake.

[0017] Preferably, a tangential force, in particular a frictional or braking force, of the magnetic track brake can be determined by measuring the force, preferably at the bearing points of the magnetic track brake, in particular by force measuring cells or other suitable sensors.

[0018] Preferably, the values ​​determined in this way are further processed to determine the final contact and / or tangential force using computational models, e.g. by taking into account the geometric and physical properties of the magnetic track brake.

[0019] Furthermore, the available frictional engagement between wheel and running surface is preferably determined by determining a coefficient of friction between magnetic track brake and running surface and deriving an available frictional engagement between wheel and running surface from the determined coefficient of friction.

[0020] Thus, the friction behavior of the magnetic track brake on the running surface can advantageously be determined in the form of the coefficient of friction, from which the friction behavior of the wheel-running surface pairing can then be derived.

[0021] The at least one contact force is preferably oriented essentially perpendicular to the running surface of the rail.

[0022] In other advantageous embodiments, the contact force, or the determined contact force, is not oriented perpendicular to the running surface of the rail, whereby this is preferably taken into account in further processing, whereby a determination of a contact force with a perpendicular orientation to the running surface of the rail is particularly preferably obtained from this.

[0023] Preferably, the at least one tangential force is aligned essentially parallel to the running surface of the rail and / or parallel to a direction of travel of the rail vehicle.

[0024] In other embodiments, the tangential force, or the determined tangential force, is not aligned parallel to the running surface of the rail and / or parallel to a direction of travel of the rail vehicle, whereby this is preferably taken into account in further processing, whereby a determination of a tangential force with parallel alignment to the running surface of the rail and / or the direction of travel of the vehicle is particularly preferably carried out.

[0025] Preferably, preparation for further processing of contact and / or tangential force is carried out by filtering and / or averaging and / or plausibility checks.

[0026] Preferably, the determined forces are processed using mathematical filtering methods, preferably eliminating unwanted noise or unwanted vibration excitations from the determined values.

[0027] Preferably, several forces of several magnetic track brakes are mathematically averaged, thereby obtaining an average contact force and an average tangential force.

[0028] Preferably, individual determined contact and / or tangential forces are checked for plausibility and thus examined for possible errors in the determination of these forces.

[0029] Plausibility can preferably be verified by comparison with other forces of other magnetic track brakes, or particularly preferably by comparison with predetermined force values, for example from a characteristic map.

[0030] Preferably, the processing of the at least one contact force and the at least one tangential force into an available force transmission takes into account geometric and physical boundary conditions between the at least one magnetic track brake and / or the at least one wheel and / or the running surface and / or the environment.

[0031] Since the determination of the available frictional contact between the running surface of the wheel and the running surface of the rail is indirectly carried out by determining the frictional contact, in particular the coefficient of friction, between at least one magnetic track brake and the running surface of the rail, the determination of the available frictional contact between wheel and rail is preferably carried out by taking into account geometric and physical boundary conditions between rail, wheel and magnetic track brake.

[0032] Preferably, the distance of the at least one magnetic track brake to the wheels is taken into account, whereby the distance in the direction of travel or the distance in the vertical direction or both are considered.

[0033] Preferably, the weight of the rail vehicle is taken into account, and particularly preferably the resulting load on individual bogies, especially individual wheels, which has an influence on the transmissible force between wheel and rail.

[0034] Preferably, the temperature of the environment and, more preferably, of the individual components, i.e., preferably the magnets of the magnetic track brake, the running surface of the rail, and the wheels, is taken into account. The temperature has an influence on the available traction.

[0035] Preferably, the temperature is determined by sensors, in particular by sensors already installed on the vehicle or by additionally provided sensors. These sensors are especially preferably designed for non-contact temperature measurement. This allows the temperature of the rail's running surface to be determined without contact, preferably by an infrared sensor.

[0036] In another advantageous embodiment of the invention, the temperature of the individual components is determined based on a measured ambient temperature. This is preferably achieved using characteristic maps or threshold values, or more preferably, computational models, from which the temperatures of the individual components can be determined.

[0037] Preferably, the vehicle speed is taken into account when determining the temperature of the individual components. In this process, the cooling effect of the airflow associated with the vehicle speed is preferably considered in computational models or characteristic maps, thus influencing the temperature of the individual components.

[0038] Preferably, the processing of the at least one contact force and the at least one tangential force to create an available force transmission takes into account material-specific boundary conditions between the at least one magnetic track brake and / or the at least one wheel and / or the running surface of the rail.

[0039] The contact between the wheel and the rail running surface is generally a contact between two steel components. The contact between the magnets or sliding shoes of the magnetic track brake and the rail running surface is usually different, meaning that the frictional behavior, which is inherently different between the magnets of the magnetic track brake and the rail running surface compared to the contact between the wheel and the rail running surface, must preferably be taken into account during further processing.

[0040] This consideration can preferably be achieved through characteristic maps and particularly preferably through computational models. For example, it is possible to determine a scaling factor through preliminary investigations, whereby the determined coefficient of friction between the magnetic track brake and the rail can be scaled to the currently available frictional engagement between the wheel and the running surface of the rail.

[0041] Preferably, the coefficient of friction between the magnetic track brake and the rail, as well as the frictional engagement between the wheel and the rail, is calculated as the quotient of the at least one tangential force and the at least one contact force, as follows: Tangential force / contact force

[0042] Preferably, when determining the available frictional contact between wheel and rail, a speed and / or an acceleration of the rail vehicle and / or their influence on an axle load distribution of the rail vehicle are processed.

[0043] Preferably, the influence of accelerations or decelerations on the axle load and / or the load of individual wheels is determined, and this influence is taken into account when determining the available traction. This determination of the axle and / or wheel loads is preferably carried out using computational models and particularly preferably using sensors, especially force sensors or, for example, pressure sensors in a pneumatic chassis of the rail vehicle.

[0044] According to the invention, the at least one magnetic track brake is used in the execution of the method in such a way that no significant deceleration of the rail vehicle occurs. Determining the available traction is thus possible while the vehicle is in motion, and the magnetic track brake does not negatively affect the operation of the vehicle, and in particular the comfort of passengers, through noticeable deceleration. This makes it possible to determine the available traction even without using the magnetic track brake to decelerate the vehicle.

[0045] According to the invention, a magnetic track brake is further provided for carrying out the method described above, wherein this magnetic track brake is designed to be installed in or on a rail vehicle. It also has at least one sensor system designed to acquire information suitable for determining at least one contact force and / or at least one tangential force between the magnets or sliding shoes of the at least one magnetic track brake and a running surface of the rail.

[0046] The sensors primarily have access to the electric current used to build up the magnetic field of the magnetic track brake, which flows through the coils of the electromagnets of the magnetic track brake.

[0047] In another advantageous embodiment, the sensor system is designed to determine the forces, preferably at the bearing points of the actuating cylinders.

[0048] In another advantageous embodiment, the sensor system is designed to determine, for example, pneumatic pressure in the actuating cylinders in order to be able to infer a contact force from this.

[0049] The magnetic track brake has at least one control device for determining the coefficient of friction between the magnetic track brake and the rail and / or for executing the process steps.

[0050] The control device is designed to actuate the magnetic track brake in such a way that the previously described procedure, in particular by applying the magnets or the sliding shoes to the running surface of the rail, is carried out without significant delay to the rail vehicle. For this purpose, the control device is preferably designed to allow an electric current to flow as precisely, precisely, and / or minimally as possible to generate the magnetic field.

[0051] Preferably, the sensor system of the magnetic track brake is a sensor system specifically designed for carrying out this method and / or a sensor system already present in or on the rail vehicle.

[0052] This allows the process to be advantageously carried out using sensors already present in the rail vehicle, thereby reducing costs and setup effort.

[0053] Preferably, however, new sensors designed for the process can also be installed to advantageously enable an accurate determination of the required values.

[0054] Preferably, the at least one sensor is in contact with the magnetic track brake via at least one data connection, and / or a mechanical connection, and / or a pneumatic connection, and / or an electrical connection in order to collect appropriate information for determining the contact and tangential forces.

[0055] Preferably, the at least one control device is in contact with the magnetic track brake and / or the sensors via at least one data connection, and / or a mechanical connection, and / or a pneumatic connection, and / or an electrical connection in order to obtain corresponding information from the sensors and to control the magnetic track brake.

[0056] Preferably, the at least one control device is designed to control the magnetic track brake.

[0057] The control device is preferably designed to control the magnetic track brake for its primary use, braking the rail vehicle, and in a further application to control it in such a way that the previously described method, in particular by applying the magnets to the running surface of the rail, is made possible without significant delay to the rail vehicle.

[0058] The application case “braking” and the application case “determining the frictional connection” can preferably also be carried out simultaneously by a magnetic track brake.

[0059] In a further advantageous embodiment of the invention, a computer program product is provided with program code stored on a machine-readable medium. When executed on a processing device, such as a control device, this code causes the control device to execute the method described above, thus enabling it to be preferably configured to perform this method. This makes it possible to enable existing control devices to perform the method described herein, thereby eliminating the need to replace the control device.

[0060] In a further advantageous embodiment of the invention, a rail vehicle is provided, comprising at least one previously described magnetic track brake, in order to enable the rail vehicle to carry out the previously described method.

[0061] The order in which the previously described procedure is carried out is not determined by the enumerated order of the individual steps and features. Rather, further embodiments are conceivable in which the at least one tangential force is determined before or simultaneously with the at least one contact force.

[0062] It is also conceivable to determine the available force transmission preferably at the beginning of the process from stored contact and tangential force values ​​and to subsequently update it preferably by repeatedly processing the process.

[0063] Furthermore, repeating the process preferably makes it possible to identify and preferably discard potentially implausible frictional values ​​by comparing them with frictional values ​​from further runs of the process.

[0064] The invention is described below using preferred embodiments with reference to the accompanying drawings.

[0065] In detail: Fig. 1. An overall view of a bogie including magnetic track brake, attached to a rail vehicle. Fig. 2 the same bogie made of Fig. 1, however with a lowered magnetic track brake.

[0066] Fig. Figure 1 shows an overall view of a bogie 16, which is equipped with a magnetic track brake 20 in a high-mounted suspension and attached to a suggested rail vehicle 10. The wheels 18 of the rail vehicle 10 are rotatably mounted on the bogie 16. The wheels 18 roll on the running surface of the rail 12 and enable the rail vehicle 10 to move in the direction of travel 14. In this illustration, only one rail vehicle 10 is shown. Additional bogies 16, connected to the rail vehicle 10, can be attached in and against the direction of travel 14. Furthermore, other rail vehicles can be coupled to the rail vehicle 10.

[0067] Such a configuration corresponds to the current state of the art and can be found in various forms on rail vehicles. The illustrated configuration of the bogie 16, the wheels 18, and the magnetic track brake 20 represents only one embodiment from the existing state of the art. Other bogies 16 with different wheel configurations are conceivable. The illustrated configuration was chosen to explain the functionality of the invention; however, it is not intended to limit the invention to the selected configuration.

[0068] The magnetic track brake 20 typically has pneumatic actuating cylinders 22 attached to the bogie 16, which in turn are connected to a magnet carrier 24. The magnet carrier 24 is equipped with magnets 26, in particular electromagnets. For the sake of clarity, other elements that typically belong to the construction of a magnetic track brake 20, such as the power supply for the electromagnets, have been omitted.

[0069] The function of the depicted magnetic track brake 20 in high suspension is as follows. Upon activation, the magnet carrier 24 is lowered towards the running surface of the rail 12 by means of the actuating cylinders 22, so that the magnets 26 come into contact with the running surface of the rail 12, or approach it to a minimum distance. To generate a braking force that slows the rail vehicle 10 against the direction of travel 14, a magnetic field is generated by the electromagnets 26 in the magnet carrier 24, which are wound by a coil. For this purpose, the coil is supplied with an electric current. The resulting magnetic field presses the magnets 26 against the running surface 12 of the rail.

[0070] Fig.Figure 2 shows this situation. The magnets 26 are pulled in the direction of travel 14 over the running surface 12 of the rail, whereby a braking effect on the rail vehicle 10 is caused by a frictional force as a tangential force 42 as a result of a contact force 40 of the magnetic track brake 20, in particular of the magnets 26, on the running surface 12 of the rail.

[0071] In addition, a sensor 30 and a control device 32 are indicated by dashed lines in this illustration, but these do not necessarily have to be located in the bogie 16.

[0072] The sensor 30 is designed to determine, on the one hand, the contact force 40, and on the other hand, the tangential force 42 of the magnets 26 on the running surface 12 of the rail.

[0073] The control device 32 is designed to control the magnetic track brake 20 and the sensor system 30, in order to carry out the intended operation of the magnetic track brake 20 to generate a braking force and to carry out the procedure described above.

[0074] It should be noted that the illustrated embodiment has two actuating cylinders 22. Only the interaction of a magnetic track brake 20 with a rail 12 is shown here. The same arrangement is usually found on the opposite side of the rail vehicle 10, i.e., behind the plane of the drawing in this view. Furthermore, the configuration shown does not limit the subject matter of the invention. Rather, other embodiments with only one actuating cylinder or with more than two actuating cylinders are conceivable. Other designs of magnetic track brakes are also suitable for carrying out the method, as explained above.

[0075] The present invention is not limited to the embodiments described above. Rather, further embodiments are conceivable which can be obtained from a combination of the embodiments described above, or which can be formed by obvious modifications of these embodiments. REFERENCE MARK LIST 10 rail vehicles 12 Rail (track surface) 14 Direction of travel 16 bogie 18-inch wheel 20 magnetic track brakes 22 actuating cylinders 24 magnetic carriers 26 magnets (electromagnets) 30 sensors 32 Control device 40 contact force 42 Tangential force (frictional force)

Claims

[1] Method for determining the available frictional contact between at least one wheel (18) of a rail vehicle (10) and a running surface (12) of a rail on which the at least one wheel (18) rolls, comprising the following steps: - Contact at least one magnetic track brake (20) with the running surface (12) of the rail, - Determine at least one contact force (40) between the at least one magnetic track brake (20) on the running surface (12), - Determine at least one tangential force (42) between at least one magnetic track brake (20) and the running surface (12), - Determining the available frictional engagement between wheel (18) and driving surface (12) by processing at least one contact force (40) and at least one tangential force (42), wherein the at least one magnetic track brake (20) is used in such a way that no significant deceleration of the rail vehicle (10) occurs, and wherein the at least one magnetic track brake (20) is used in such a manner, that the procedure for determining the available frictional engagement is separate from a method for generating a braking force for braking the rail vehicle (10) is carried out. [2] Method according to claim 1, wherein determining the at least one contact force (40) and / or the at least one tangential force (42) by means of - Sensors, and / or - Computational models this occurs, and / or The determination of the available frictional contact between wheel (18) and running surface (12) is carried out by determining a coefficient of friction between magnetic track brake and running surface and deriving an available frictional contact between wheel (18) and running surface (12) from the determined coefficient of friction. [3] Method according to claim 1 or 2, wherein the at least one contact force (40) is oriented substantially perpendicular to the driving surface (12). [4] Method according to any one of claims 1 to 3, wherein which exerts at least one tangential force (42) substantially parallel to the driving surface (12), and / or is aligned parallel to a direction of travel (14) of the rail vehicle (10). [5] Method according to one of the preceding claims, wherein the at least one contact force (40) and / or the at least one tangential force (42) for processing by means of - Filtering and / or - Notification and / or - Plausibility checks are being prepared. [6] Method according to one of the preceding claims, wherein the processing of the at least one contact force (40) and the at least one tangential force (42) to an available force transmission takes into account geometric and physical boundary conditions between the at least one magnetic track brake (20) and / or the at least one wheel (18) and / or the running surface (12) and / or an environment. [7] Method according to one of the preceding claims, wherein the processing of the at least one contact force (40) and the at least one tangential force (42) to an available force transmission takes place taking into account material-specific boundary conditions between the at least one magnetic track brake (20) and / or the at least one wheel (18) and / or the running surface (12). [8] Method according to one of the preceding claims, wherein the available force transmission is calculated as the quotient of the at least one tangential force (42) and the at least one contact force (40). [9] Method according to one of the preceding claims, wherein the speed and / or acceleration of the rail vehicle (10) and / or their influence on an axle load distribution of the rail vehicle (10) are processed in determining the available frictional contact. [10] Magnetic track brake (20) for carrying out the method according to one of claims 1 to 9, designed to be installed in or on a rail vehicle (10), comprising at least one sensor system (30) designed to determine information suitable for determining at least one contact force (40) and / or at least one tangential force (42) between a magnet (26) of the at least one magnetic track brake (20) and a running surface (12), and at least one control device (32) for determining the available frictional engagement and / or for processing the method steps according to one of claims 1 to 9, which is designed to carry out the method according to one of claims 1 to 9. [11] Magnetic track brake (20) according to claim 10, wherein which at least one sensor (30) at least - a data connection, and / or - a mechanical connection, and / or - a pneumatic connection, and / or - an electrical connection with the magnetic track brake (20). [12] Magnetic track brake (20) according to one of claims 10 or 11, wherein the at least one control device (32) at least - a data connection, and / or - a mechanical connection, and / or - a hydraulic connection, and / or - a pneumatic connection, and / or - an electrical connection with the magnetic track brake (20) and / or the at least one sensor (30). [13] Magnetic track brake (20) according to one of claims 10 to 12, wherein the at least one control device (32) is designed for controlling the magnetic track brake (20). [14] Computer program product comprising program code stored on a machine-readable medium which, when executed on a processing device, causes the processing device to execute the method according to at least one of claims 1 to 9. [15] Rail vehicle (10) comprising at least one magnetic track brake (20) according to any one of claims 10 to 13.

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