METHOD FOR MONITORING A RAILWAY SYSTEM AND SENSOR ARRANGEMENT FOR A RAILWAY SYSTEM

A method for monitoring a railway system and a sensor arrangement for a railway system are provided.

For monitoring a railway track it is necessary to monitor the state of movable railway elements such as tongue rails and railway frogs. Tongue rails and railway frogs are components of railway switches. A prerequisite for a safe passage of a rail vehicle over a railway switch is that the movable railway elements of the railway switch are arranged at predefined positions. This can mean, that a tongue rail is either in a position where it is in direct contact or close to direct contact with a stock rail of the railway switch or in a position where the tongue rail is spaced apart from the stock rail far enough so that a wheel of a passing rail vehicle can safely pass the railway switch. The same is true for railway frogs. It is therefore necessary to monitor the state of these movable railway elements. Only if the movable railway elements are detected to be in a state in which a rail vehicle can safely, this means without the risk of a derailment, pass the railway switch, the rail vehicle is allowed to pass the railway switch. It is furthermore necessary to monitor if the movable railway elements stay at the measured positions.

It is an objective to provide a method for monitoring a railway system with an improved accuracy. It is further an objective to provide a sensor arrangement for a railway system with an improved accuracy.

These objectives are achieved with the independent claims. Further embodiments are the subject of dependent claims.

According to at least one embodiment of the method for monitoring a railway system, the method comprises the step of arranging a sensor below a movable railway element of the railway system. The movable railway element can for example be a tongue rail or a railway frog. Thus, the movable railway element is a part of the railway system or a part of a railway switch. The movable railway element can be a part of a rail or it can comprise a rail. Another expression for “tongue rail” is “switch rail”. Another expression for “railway frog” is “movable frog”.

The movable railway element can have an elongated shape. The railway system can be a railway switch. Thus, the method can be a method for monitoring a railway switch. Other expressions for “railway switch” are “point switch”, “railroad switch”, “track switch”, “turnout”, “set of point”, “points”, “switch”, “point”. That the sensor is arranged below the movable railway element can mean, that the sensor is arranged at a side of the movable railway element which faces away from the side where wheels of a rail vehicle can pass or move on the movable railway element. In other words, the sensor is arranged at a side of the movable railway element which faces away from a side which faces wheels of a rail vehicle when a rail vehicle passes over the movable railway element.

The sensor can comprise at least one contactless position sensor, at least one metal sensor, at least one inductive sensor or at least one capacitive sensor. It is also possible that the sensor comprises at least two or a plurality of one or more than one of these sensors. The sensor can comprise a two-dimensional array of one or more than one of these sensors.

The method further comprises measuring a spatial position of at least a segment of the movable railway element by a contactless measurement by the sensor. A spatial position can be a position in space. This means, the sensor can measure where the segment of the movable railway element is arranged. The sensor can have a sensing range within which the sensor is configured to measure the spatial position of the segment of the movable railway element. The sensing range can be a volume or an area. The sensor can be configured to detect the movement of electrically conductive material within the sensing range. Thus, the sensing range is at least partially arranged outside of the sensor. The sensor can be configured to measure the spatial position of the segment for the whole range within which the movable railway element is configured to move.

As the sensor can only detect parts of the movable railway element that are arranged within the sensing range of the sensor, a spatial position of at least a segment of the movable railway element is measured by the sensor. This means, if the movable railway element is significantly larger than the sensor, the sensor can only measure the spatial position of a segment of the movable railway element. The sensor can be configured to measure the spatial position of that segment of the movable railway element that is arranged within the sensing range of the sensor. The segment of the movable railway element is a part of the movable railway element. The segment is not necessarily separated from other parts of the movable railway element. It is rather possible that it is not visible where the segment begins and where it ends. The position of the segment in the movable railway element is defined by the prerequisite that the segment is arranged within the sensing range of the sensor. This means, the segment of the movable railway element is that part of the movable railway element that the sensor is configured to detect. The sensor is not configured to detect the spatial position of parts of the movable railway element that are arranged outside of the sensing range.

The segment of the movable railway element can be a front segment of the movable railway element. This means, that the segment can be arranged at the position of the movable railway element which is configured to be moved by the largest distance compared to other segments of the movable railway element. If the movable railway element is a tongue rail, the segment can be arranged at that position of the tongue rail which is supposed to be in direct contact with a non-movable rail of the railway system in one of the end positions of the tongue rail.

That the sensor is configured to measure the spatial position in a contactless measurement can mean, that the sensor is not in direct contact with the movable railway element. This means, the sensor is arranged spaced apart from the movable railway element. The sensor can comprise a contactless position sensor or the sensor can be a contactless position sensor. This means, the sensor is configured to determine the position of the segment of the movable railway element without mechanical contact to the movable railway element.

According to at least one embodiment of the method the sensor is configured to differentiate between at least two different spatial positions of the segment of the movable railway element. This can mean, that the sensor is configured to measure at least two different spatial positions of the segment of the movable railway element. Thus, for two different spatial positions of the segment of the movable railway element, the sensor is configured to determine the spatial position of the segment. The two different spatial positions are arranged spaced apart from each other. The two different spatial positions can be end positions of the movable railway element. The end positions can be the two positions that the movable railway element can reach that are arranged the furthest apart from each other. It is also possible that the two different spatial positions are end positions of the segment of the movable railway element. The sensor can be arranged below the segment of the movable railway element.

The respective spatial position relates to the distance between the segment of the movable railway element and a rail of the railway system. The rail of the railway system can be a stock rail. Another expression for “stock rail” is “closure rail”. The stock rail is a nonmovable rail of a railway switch. This means, the stock rail is arranged at a fixed position. The movable railway element can be arranged at different positions. For the case that the movable railway element is in direct contact with the rail, the measured distance is 0. For the case that the movable railway element is not in direct contact with the rail, the distance between the segment and the rail is greater than 0. That the respective spatial position relates to the distance between the segment and the rail can mean, that the spatial position of the segment is measured in relation to the rail. In other words, the measured spatial position gives the distance between the segment and the rail.

The method has the advantage that the actual spatial position of the segment of the movable railway element can be measured. Thus, not only end positions of the movable railway element, as for example an opened and a closed position, can be measured, but the actual spatial position of the segment. Measuring the actual position instead of only end positions has the advantage that the state, this means the position, of the movable railway element can be analyzed with an improved accuracy and it is possible to monitor defects and wear of the movable railway element.

The measured spatial position is given as the distance between the segment and the rail. This has the advantage that a parameter of interest is measured. For monitoring a railway system with a movable railway element it is necessary to determine where the movable railway element is arranged with respect to the non-movable rail. The distance between the movable railway element and the non-movable rail gives the space that is available for a wheel of a rail vehicle passing the railway system. By monitoring the available space it is possible to determine if a rail vehicle can safely pass the railway system or railway switch. For a safe passage of a rail vehicle it is necessary that the movable railway element is arranged either close enough to the rail or far enough away from the rail. By measuring the distance between the segment and the rail this parameter which is necessary for monitoring the railway system is determined.

Another advantage is that the spatial position is determined contactless. Thus, it is not necessary to mechanically connect the sensor to the movable railway element. In this way, installing and maintaining the sensor is simplified in comparison to a sensor which requires a mechanical contact to the movable railway element. The sensor described herein can be comprised by a sensor arrangement. The sensor arrangement can also comprise a rail claw. The sensor can be connected with the rail via the rail claw. The sensor is mechanically connected to the rail claw and the rail claw is mechanically connected with the rail. A further mechanical connection of the sensor to other parts of the railway system is not required. Also, no drilling is required. This means that the time required for installing the sensor is reduced. With this, also the time for which it is required to stop railway traffic on the railway system can be reduced. This also increases the safety for personnel installing or maintaining the sensor as the time that they need to spend on or at the rails is reduced.

That the sensor is configured to measure contactless also has the advantage that the sensor is not exposed to friction or other mechanical impacts. Thus, a damage of the sensor due to mechanical contact to the movable railway element is avoided.

According to at least one embodiment of the method the movable railway element comprises a tongue rail. The movable railway element can be comprised by a railway switch. The method enables advantageously to monitor movable parts of the railway system such as a tongue rail. In order to avoid a derailment of a rail vehicle it is necessary to monitor movable parts of the railway system.

According to at least one embodiment of the method the movable railway element comprises a railway frog. According to at least one embodiment of the method the sensor is configured to differentiate between three different spatial positions of the segment of the movable railway element. The sensor is configured to measure at least three different spatial positions of the segment of the movable railway element. Thus, for three different spatial positions of the segment of the movable railway element, the sensor is configured to determine the spatial position of the segment. The three different spatial positions are arranged spaced apart from each other. The sensor is thus not only configured to determine the end positions of the segment of the movable railway element but also at least one position which is no end position. With this, a defect of the movable railway element can be specified in more detail, as the actual spatial position of the segment of the movable railway element is measured. It is furthermore possible to monitor wear of the movable railway element as the change of the actual position of the segment when it is in its end positions can be monitored. After a movable railway element has been used for a while it is possible that the segment does not reach the exact spatial position where it is supposed to be in its closed or open state anymore. For example, in a closed state of a movable railway element, the movable railway element is supposed to be in direct contact with a neighboring non- movable rail. After a while, the movable railway element might not reach the position of direct contact with the neighboring rail anymore due to wear of the movable railway element. By measuring the actual spatial position of the segment of the movable railway element, this deviation from the position of direct contact with the neighboring rail can be detected and monitored. The same is possible for the open position of the movable railway element, where the movable railway element is in a position where a wheel of a passing rail vehicle can pass between the movable railway element and the neighboring rail. Consequently, the position of the movable railway element can be monitored with an increased accuracy.

According to at least one embodiment of the method the sensor is configured to differentiate between four different spatial positions of the segment of the movable railway element. The sensor is configured to measure at least four different spatial positions of the segment of the movable railway element. Thus, for four different spatial positions of the segment of the movable railway element, the sensor is configured to determine the spatial position of the segment. The four different spatial positions are arranged spaced apart from each other. Monitoring the actual position of the segment improves the accuracy. According to at least one embodiment of the method the sensor is configured to differentiate between a plurality of different spatial positions of the segment of the movable railway element. The sensor is configured to measure a plurality of different spatial positions of the segment of the movable railway element. Thus, for a plurality of spatial positions of the segment of the movable railway element, the sensor is configured to determine the spatial position of the segment. The different spatial positions are arranged spaced apart from each other or next to each other. Monitoring the actual position of the segment improves the accuracy.

According to at least one embodiment of the method the spatial position of the segment of the movable railway element is measured for a first arrangement of the movable railway element, where in the first arrangement of the movable railway element the segment of the movable railway element is in its closest position with respect to the rail, and the spatial position of the segment of the movable railway element is measured for a second arrangement of the movable railway element, where in the second arrangement of the movable railway element the segment of the movable railway element is arranged spaced apart from the rail. As the movable railway element can be moved, it can be arranged in different arrangements. In the first arrangement the movable railway element can be in direct contact with the rail. It is also possible that in the first arrangement the segment is in direct contact with the rail. Thus, in the first arrangement the movable railway element is in one of its end positions. In the second arrangement the movable railway element is arranged at a different position in comparison to the first arrangement. It is also possible that in the second arrangement the segment is arranged at a different position in comparison to the first arrangement. The position of the segment in the first arrangement can be spaced apart from the position of the segment in the second arrangement. However, the second arrangement is not necessarily an end position of the movable railway element. This measurement of the spatial position of the segment in the first arrangement and the second arrangement can be carried out in a calibration step. This means, this measurement of the spatial position of the segment in the first arrangement and the second arrangement can be carried out before the method is carried out in a situation with railway traffic. The two measured spatial positions can advantageously be employed as reference positions for later measurements of spatial positions of the segment. According to at least one embodiment of the method in the second arrangement of the movable railway element the segment of the movable railway element is arranged at its maximum distance from the rail. The movable railway element can have a range within which it can be moved. Thus, also the segment has a range within which it can be moved. In the first arrangement of the segment, the segment is arranged at a position at one end of this range. In the second arrangement of the segment, the segment is arranged at the opposite end of this range. In the second arrangement the segment is arranged at its furthest possible distance from the rail. The first arrangement can be one of the end positions of the segment and the second arrangement can be the other end position. The two measured spatial positions can advantageously be employed as reference positions for later measurements of spatial positions of the segment.

According to at least one embodiment of the method the spatial position measured for the first arrangement of the movable railway element and the spatial position measured for the second arrangement of the movable railway element are saved by the sensor as reference positions. The spatial position measured for the first arrangement of the movable railway element can be saved as a first reference position. The spatial position measured for the second arrangement of the movable railway element can be saved as a second reference position. The reference positions can be employed for providing the spatial position of the segment. For example, the spatial position of the segment can be given with respect to the first reference position. It is also possible that the spatial position of the segment is given with respect to the second reference position. It is also possible that the spatial position of the segment is given with respect to the first reference position and the second reference position. The reference positions can be saved in a calibration step. Thus, the reference positions can be saved in a step which is carried out before the method is carried out for the case that at least one rail vehicle is moving within the railway system. Saving the reference positions has the advantage that the spatial position can be provided with respect to at least one of the reference positions. Thus, it can be monitored how far the segment is spaced from the rail. With this information it can be decided if a rail vehicle can safely pass the railway system. This is for example the case when the segment is arranged close enough to the rail or when the segment is arranged far enough from the rail. Advantageously, the reference positions can be determined without mechanical contact to the movable railway element and the sensor. It is thus not necessary to enter the area of the railway system. Thus, determining the reference positions is less complicated than for the case that a mechanical contact is required and it is safer as no entering in the railway system is required.

According to at least one embodiment of the method in the first arrangement of the movable railway element a first edge of the movable railway element is detected by the sensor, a second edge of the movable railway element is arranged opposite to the first edge and the second edge is not arranged above the sensor in the first arrangement. The second edge of the movable railway element can be arranged at a side of the movable railway element facing the rail. The first edge of the movable railway element can be arranged at a side of the movable railway element facing away from the rail. In the first arrangement the movable railway element is arranged closer to the rail than the sensor. Thus, the second edge which is closer to the rail than the first edge is not arranged above the sensor in the first arrangement. Instead, only a part of the movable railway element is arranged above the sensor in the first arrangement. The second edge can be arranged outside of the sensing range of the sensor in the first arrangement of the movable railway element. The first edge can be arranged within the sensing range of the sensor in the first arrangement. As the sensor can be configured to detect the movement of electrically conductive material within the sensing range, the movement of the first edge can cause a difference in a signal detected by the sensor. The movable railway element can comprise an electrically conductive material. Thus, a movement of the first edge is detected by the sensor for the first arrangement. Also for positions close to the first arrangement a movement of the first edge is detected by the sensor. By combining the information that a movement of the first edge is detected for the first arrangement and positions close to the first arrangement and the information at which side of the movable railway element the first edge is arranged, the spatial position of the segment can be determined. For determining the spatial position at least one of the reference positions is employed. As the first edge is employed for determining the spatial position, the sensing range can be smaller than the range within which the segment can move. Consequently, the sensor can have a compact size.

According to at least one embodiment of the method in the second arrangement of the movable railway element the second edge of the movable railway element is detected by the sensor and the first edge is not arranged above the sensor in the second arrangement. In the second arrangement the movable railway element is arranged further away from the rail than the sensor. Thus, the second edge which is closer to the rail than the first edge is arranged above the sensor in the second arrangement. Only a part of the movable railway element is arranged above the sensor in the second arrangement. The first edge can be arranged outside of the sensing range of the sensor in the second arrangement of the movable railway element. The second edge can be arranged within the sensing range of the sensor in the second arrangement. A movement of the second edge is detected by the sensor for the second arrangement. Also for positions close to the second arrangement a movement of the second edge is detected by the sensor. By combining the information that a movement of the second edge is detected for the second arrangement and positions close to the second arrangement and the information at which side of the movable railway element the second edge is arranged, the spatial position of the segment can be determined. For determining the spatial position at least one of the reference positions is employed. As the second edge is employed for determining the spatial position, the sensing range can be smaller than the range within which the segment can move. Consequently, the sensor can have a compact size.

According to at least one embodiment of the method a passing range of spatial positions of the segment of the movable railway element is selected, and a pass signal is provided for the case that a spatial position within the passing range is measured. For the spatial positions within the passing range the segment of the movable railway element is close enough to the rail so that a rail vehicle can pass the railway system or the segment of the movable railway element is spaced apart from the rail far enough so that a rail vehicle can pass the railway system. The size of the passing range depends on the size of the wheels of passing rail vehicles and can also depend on regulations or laws in the country where the sensor is employed. The passing range is selected in such a way that for spatial positions within the passing range a rail vehicle can pass the railway system without a derailment. Also in this case it is advantageous to measure the actual spatial position of the segment since it can be determined if the segment is arranged outside of the passing range. If only the two end positions were measured, other dangerous situations might not be identified beforehand. Therefore, the method enables a safe railway traffic over the railway system. In addition, it is possible to select the passing range in such a way that it complies with national regulations or laws.

According to at least one embodiment of the method for at least one arrangement of the movable railway element delimiting the passing range the spatial position of the segment is measured by the sensor in a contactless measurement. An arrangement delimiting the passing range can be an arrangement of the movable railway element where the spatial position of the segment is within the passing range and where an adjacent spatial position is outside of the passing range. For measuring the spatial position of the segment for at least one arrangement of the movable railway element delimiting the passing range an obstacle or a plate with a known size is arranged between the rail and the movable railway element. Thus, the movable railway element cannot reach its closest position with respect to the rail but is kept at a distance which is given by the size of the obstacle or the plate. The size of the obstacle or the plate can be selected in such a way that it has the size of the largest slit between the rail and the movable railway element which is allowed for the closed position of the movable railway element. In this way, the arrangement delimiting the passing range is reached. For this arrangement the spatial position of the segment is measured and can be saved by the sensor as a further reference position. Saving the further reference position has the advantage that the spatial position can be provided with respect to the further reference position and it can thus be determined if the measured spatial position is within the passing range.

According to at least one embodiment of the method a stopping range of spatial positions of the segment of the movable railway element is selected, and a stop signal is provided for the case that a spatial position within the stopping range is measured. For the spatial positions within the stopping range the segment of the movable railway element is spaced apart from the rail by a distance that does not enable a rail vehicle to pass the railway system or that leads to a derailment of a rail vehicle passing the railway system. It is also possible that for the spatial positions within the stopping range the segment of the movable railway element is spaced apart from the rail by a distance that leads to a risk of a derailment of a rail vehicle passing over the railway system. The size of the stopping range depends on the size of the wheels of passing rail vehicles and can also depend on regulations or laws in the country where the sensor is employed. The stopping range can comprise all spatial positions that are not arranged within the passing range. The stop signal can be provided to a monitoring unit or a signal box. In case that a stop signal is provided, the passage of rail vehicles over the railway system can be forbidden or stopped. In this way, accidents at the railway system are avoided which increases the safety of the railway traffic.

According to at least one embodiment of the method for at least one arrangement of the movable railway element delimiting the stopping range the spatial position of the segment is measured by the sensor in a contactless measurement. This measurement is carried out analog to the measurement of the spatial position in an arrangement delimiting the passing range.

According to at least one embodiment of the method the spatial position of the segment of the movable railway element is measured at different points in time for the case that the segment of the movable railway element is in its closest position with respect to the rail. With this, changes with time of the movable railway element can be monitored. If a movable railway element is employed for a longer time period it might degrade or show signs of wear. This can have the consequence that the segment does not reach the position of direct contact with the rail anymore but only reaches a position close to the rail. By measuring the spatial position of the segment for its closest position with respect to the rail at different points in time the changing state of the movable railway element can be monitored. This enables for example that the movable railway element is repaired or maintained for the case that the closest possible position with respect to the rail is too far away from the rail for a safe passage of a rail vehicle. It is also possible to monitor other features of the movable railway element. For example, the spatial position can be measured for different points in time for different arrangements of the movable railway element. With this, the dynamic behavior of the movable railway element can be monitored. From this, it can be determined if the movable railway element works properly. In addition, it cannot only be controlled if the movable railway element is in a position where it is supposed to be, for example in its closed position, but it can also be monitored if the movable railway element stays in this position by measuring the spatial position of the segment at different points in time. According to at least one embodiment of the method, the method comprises arranging a further sensor below the movable railway element, and measuring a spatial position of at least a further segment of the movable railway element by a contactless measurement by the further sensor, wherein the further sensor is configured to differentiate between at least two different spatial positions of the further segment of the movable railway element, and the respective spatial position relates to the distance between the further segment of the movable railway element and a rail of the railway system. The further sensor can have the same features as the sensor. As the movable railway element can have an elongated shape the segment of the movable railway element can be at a different position in comparison to the further segment of the movable railway element. The segment can be arranged adjacent to the further segment. It is also possible that the segment is arranged spaced apart from the further segment. The movable railway element can be bent in different directions or in a different way at different positions along the movable railway element. For example, a stone or another obstacle such as snow or ice can be arranged between the movable railway element and a rail of the railway system. The movable railway element can be bent around the stone or the obstacle. However, it is possible that only a part or a segment of the movable railway element is bent. Other parts or segments of the movable railway element might not be influenced by the stone or the obstacle. For this situation it is advantageous to employ the sensor and the further sensor. With this, it is possible to monitor two different segments along the movable railway element. It is also possible to employ more than one sensor and/or more than one further sensor. Monitoring different segments of the movable railway element increases the safety. Obstacles blocking at least a part or a segment of the movable railway element can be detected. If an obstacle blocks the movable railway element in such a way, that a safe passage of a rail vehicle is not possible anymore, the respective part of the railway system can be closed for railway traffic. Thus, a derailment of a rail vehicle can be prevented.

Furthermore, a sensor arrangement for a railway system is provided. The sensor arrangement can preferably be employed in the methods described herein. This means all features disclosed for the method for monitoring a railway system are also disclosed for the sensor arrangement for a railway system and vice-versa. According to at least one embodiment of the sensor arrangement for a railway system, the sensor arrangement comprises a sensor that is configured to measure a spatial position of at least a segment of a movable railway element of the railway system in a contactless measurement. The sensor is configured to be arranged below the movable railway element. The respective spatial position relates to the distance between the segment of the movable railway element and a rail of the railway system.

According to at least one embodiment of the sensor arrangement, the sensor is configured to differentiate between at least two different spatial positions of the segment of the movable railway element. The sensor can be a two-channel sensor. This can mean, that the sensor comprises a first evaluation channel and a second evaluation channel. Some components of the sensor are connected with the first evaluation channel and other components of the sensor are connected with the second evaluation channel. The sensor can comprise a plurality of contactless position sensors or a plurality of other sensors. In this case some of the contactless position sensors or other sensors are connected with the first evaluation channel and others of the contactless position sensors or other sensors are connected with the second evaluation channel. The first evaluation channel and the second evaluation channel can be independent from each other. Employing two independent evaluation channels increases the safety. If a defect occurs in one of the channels, the other channel can operate independently from the defect channel.

The sensor arrangement can have the same advantages as the method for monitoring a railway system.

According to at least one embodiment of the sensor arrangement, the sensor comprises at least one metal sensor. The metal sensor can be configured to measure the spatial position of the segment of the movable railway element in a contactless measurement. The metal sensor is configured to detect the movement of a metal within the sensing range or within a part of the sensing range. The metal sensor is not in mechanical contact with the movable railway element. This has the advantage that the sensor is protected from damage caused by mechanical contact or friction. According to at least one embodiment of the sensor arrangement, the sensor comprises at least two or a plurality of metal sensors. The metal sensors can be arranged in a two- dimensional array. By employing more than one metal sensor the sensing range can be enlarged.

According to at least one embodiment of the sensor arrangement, the sensor comprises at least one inductive sensor. The inductive sensor can be configured to measure the spatial position of the segment of the movable railway element in a contactless measurement. The inductive sensor is configured to detect the movement of electrically conductive material within the sensing range or within a part of the sensing range. The inductive sensor can comprise at least one coil. The inductive sensor is not in mechanical contact with the movable railway element. This has the advantage that the sensor is protected from damage caused by mechanical contact or friction.

According to at least one embodiment of the sensor arrangement, the sensor comprises at least two or a plurality of inductive sensors. The inductive sensors can be arranged in a two-dimensional array. By employing more than one inductive sensor the sensing range can be enlarged.

According to at least one embodiment of the sensor arrangement, the sensor comprises at least one capacitive sensor. The capacitive sensor can be configured to measure the spatial position of the segment of the movable railway element in a contactless measurement. The capacitive sensor is configured to detect the movement of electrically conductive material within the sensing range or within a part of the sensing range. The capacitive sensor is not in mechanical contact with the movable railway element. This has the advantage that the sensor is protected from damage caused by mechanical contact or friction.

According to at least one embodiment of the sensor arrangement, the sensor comprises at least two or a plurality of capacitive sensors. The capacitive sensors can be arranged in a two-dimensional array. By employing more than one capacitive sensor the sensing range can be enlarged. The following description of figures may further illustrate and explain exemplary embodiments. Components that are functionally identical or have an identical effect are denoted by identical references. Identical or effectively identical components might be described only with respect to the figures where they occur first. Their description is not necessarily repeated in successive figures.

With figures 1 and 2 an exemplary embodiment of the sensor arrangement is shown.

With figure 3 an exemplary embodiment of the method for monitoring a railway system is described.

With figures 4, 5, 6 and 7 exemplary embodiments of the method for monitoring a railway system are described.

Figure 8 shows a further exemplary embodiment of the sensor arrangement.

Figure 1 shows an exemplary embodiment of a sensor arrangement 20 for a railway system 21. The sensor arrangement 20 is arranged at the railway system 21 which is a railway switch. The sensor arrangement 20 comprises a sensor 24 that is configured to measure a spatial position of at least a segment 34 of a movable railway element 25 of the railway system 21 in a contactless measurement and to differentiate between at least two different spatial positions of the segment 34 of the movable railway element 25. The respective spatial position relates to the distance between the segment 34 of the movable railway element 25 and a rail 23 of the railway system 21. The sensor 24 is arranged below the movable railway element 25 without mechanical contact to the movable railway element 25. The movable railway element 25 can comprise a tongue rail 26 of the railway switch. The railway switch also comprises the rail 23. The rail 23 can be a stock rail. The movable railway element 25 can be moved between two different end positions. In one end position, a front part of the movable railway element 25 is in direct contact or close to direct contact with the rail 23 at a connection point 27. In the other end position, the distance between the movable railway element 25 and the rail 23 is large enough so that wheels of a rail vehicle can pass between the rail 23 and the movable railway element 25 without a derailment of the rail vehicle. The sensor 24 can comprise at least one metal sensor, at least one inductive sensor or at least one capacitive sensor. The sensor 24 can be configured to differentiate between at least three or a plurality of different spatial positions of the segment 34 of the movable railway element 25.

Figure 2 shows an exemplary embodiment of the sensor arrangement 20 mounted to the rail 23 of the railway system 21. The sensor arrangement 20 comprises a rail claw 22 that is connected to the rail 23 of the railway system 21. Figure 2 shows a top view on the rail 23. The rail claw 22 is arranged below the rail 23. Thus, only parts of the rail claw 22 are visible in figure 2. The sensor 24 is mechanically connected with the rail claw 22. Adjacent to the rail 23 the movable railway element 25 is arranged. The sensor 24 is arranged below the movable railway element 25. Therefore, the sensor 24 is not visible in figure 2.

With figure 3 an exemplary embodiment of the method for monitoring a railway system 21 is described. In a first step SI of the method the sensor 24 is arranged below the movable railway element 25. In a second step S2 of the method the spatial position of the segment 34 of the movable railway element 25 is measured by a contactless measurement by the sensor 24. The sensor 24 is configured to differentiate between at least two different spatial positions of the segment 34 of the movable railway element 25 and the sensor 24 can be configured to differentiate between a plurality of different spatial positions of the segment 34 of the movable railway element 25. In optional further steps Sn of the method the spatial position of the segment 34 of the movable railway element 25 is measured at different points in time for the case that the segment 34 of the movable railway element 25 is in its closest position with respect to the rail 23 or for other arrangements of the movable railway element 25.

With figures 4, 5, 6 and 7 exemplary embodiments of the method for monitoring a railway system 21 are described.

In figure 4 a cross section through another exemplary embodiment of the sensor arrangement 20 is shown. Figure 4 shows a side view where a cross section through the rail 23 is shown. A rail claw 22 is arranged below the rail 23 and fixed to the rail 23 with two clamp parts 31. The different parts of the rail claw 22 are connected with each other by screws 32. The sensor 24 is arranged adjacent to the rail claw 22 and mechanically connected with the rail claw 22. Above the sensor 24 and adjacent to the rail 23, the movable railway element 25 is arranged. The sensor 24 is arranged spaced apart from the movable railway element 25. This means, the sensor 24 and the movable railway element 25 are not in mechanical contact. The movable railway element 25 is configured to be moved along a lateral direction x. The lateral direction x is indicated by an arrow in figure 4.

In figure 4 an arrangement of the movable railway element 25 is shown, which is referred to as a first arrangement. In the first arrangement of the movable railway element 25 the segment 34 of the movable railway element 25 is in its closest position with respect to the rail 23. In this case the movable railway element 25 is in direct contact with the rail 23. A top part 33 of the movable railway element 25 has a shape which fits to the shape of the top part 33 of the rail 23. At the side facing the movable railway element 25, the rail 23 comprises a region whose shape is adapted to the shape of the movable railway element 25. This means, the top part 33 of the rail 23 comprises a surface which faces the top part 33 of the movable railway element 25 and which extends parallel to a surface of the movable railway element 25 which faces the rail 23. This shape of the rail 23 and the movable railway element 25 enables this closed position of the movable railway element 25 where it is in direct contact with the rail 23. Because of the two surfaces extending parallel to each other a slit between the rail 23 and the movable railway element 25 in the closed position is avoided.

In an optional step of the method the spatial position of the segment 34 of the movable railway element 25 is measured for the first arrangement of the movable railway element 25. The measured spatial position can be saved as a first reference position.

The sensor 24 can comprise a plurality of sensor components as for example coils. The sensor components can each be configured to detect the movement of electrically conductive material within a sensing range of the respective sensor component. By employing a plurality of sensor components the sensing range of the sensor 24 can be increased. The movable railway element 25 can comprise an electrically conductive material.

The movable railway element 25 comprises a first edge 36 and a second edge 37 which is arranged opposite to the first edge 36. In figure 4 the second edge 37 is arranged closer to the rail 23 than the first edge 36. In the first arrangement the second edge 37 is not arranged above the sensor 24. However, the first edge 36 is arranged above the sensor 24. The first edge 36 of the movable railway element 25 is detected by the sensor 24.

If the sensor 24 comprises a plurality of coils, each coil has a sensing range within which it is configured to sense the movement of electrically conductive material. This means, if the movable railway element 25 enters the sensing range of a coil, the coil is partially damped. Thus, this movement of the movable railway element 25 can be detected. Once the movable railway element 25 extends over the whole sensing range of a coil, the coil is fully damped and a further movement of the movable railway element 25 does not change the state of the coil. This means, in this situation a further movement of the movable railway element 25 cannot be detected by the coil. A further movement of the movable railway element 25 can only be detected once the movable railway element 25 does not extend over the whole sensing range of the coil anymore. By evaluating the signals of the plurality of coils, the position of the movable railway element 25 can be determined. In the first arrangement the movement of the first edge 36 induces a change in the signal of the sensor 24. Thus, the first edge 36 of the movable railway element 25 is detected by the sensor 24.

With figure 5 another optional step of the method is described. Figure 5 shows the same cross section through the sensor arrangement 20 as figure 4 but the movable railway element 25 is arranged at a different position. The movable railway element 25 is arranged in a second arrangement where the segment 34 of the movable railway element 25 is arranged spaced apart from the rail 23. This means, that in the second arrangement the segment 34 is arranged spaced apart from the rail 23 further than in the first arrangement. In another optional step of the method the spatial position of the segment 34 is measured for the second arrangement of the movable railway element 25. In the second arrangement of the movable railway element 25 the segment 34 of the movable railway element 25 can be arranged at its maximum distance from the rail 23. The spatial position measured for the second arrangement can be saved as a second reference position.

In the second arrangement the first edge 36 of the movable railway element 25 is not arranged above the sensor 24 and the second edge 37 is arranged above the sensor 24. Thus, in the second arrangement the second edge 37 of the movable railway element 25 is detected by the sensor 24.

In another optional step of the method a passing range of spatial positions of the segment 34 of the movable railway element 25 is selected, and a pass signal is provided for the case that a spatial position within the passing range is measured.

In another optional step of the method a stopping range of spatial positions of the segment 34 of the movable railway element 25 is selected, and a stop signal is provided for the case that a spatial position within the stopping range is measured.

With figures 6 and 7 another optional step of the method is described. Figure 6 shows the same cross section through the sensor arrangement 20 as figure 4 but the movable railway element 25 is arranged at a different position. In figure 6 the movable railway element 25 is arranged at a position between the position shown in figure 4 and the position shown in figure 5. The movable railway element 25 is not in direct contact with the rail 23 and arranged spaced apart from the rail 23.

Figure 7 shows the same configuration as figure 6 with the only difference that a plate 30 is arranged between the rail 23 and the movable railway element 25. The plate 30 is in direct contact with the rail 23 and with the movable railway element 25. Thus, the movable railway element 25 cannot reach its closest position with respect to the rail 23 but is kept at a distance which is given by the size of the plate 30. The size of the plate 30 can be selected in such a way that it has the size of the largest slit between the rail 23 and the movable railway element 25 which is allowed for the closed position of the movable railway element 25. In this way, the arrangement delimiting the passing range is reached. For this arrangement the spatial position of the segment 34 is measured in another optional step of the method. The measured spatial position can be saved by the sensor 24 as a further reference position.

Figure 8 shows a top view on another exemplary embodiment of the sensor arrangement 20. In comparison to the embodiment shown in figure 1 the sensor arrangement 20 further comprises a further sensor 29 that is configured to measure a spatial position of at least a further segment 35 of the movable railway element 25 by a contactless measurement and to differentiate between at least two different spatial positions of the further segment 35 of the movable railway element 25. The further sensor 29 is arranged below the further segment 35. With this sensor arrangement 20 different segments 34, 35 of the movable railway element 25 can be monitored.

This patent application claims priority from European patent application 21203953.1, the disclosure content of which is hereby included by reference.

Reference numerals

20 sensor arrangement

21 railway system

22 rail claw

23 rail

24 sensor

25 movable railway element

26 tongue rail

27 connection point

28 further rail claw

29 further sensor

30 plate

31 clamp part

32 screw

33 top part

34 segment

35 further segment

36 first edge

37 second edge x lateral direction

SI, S2, Sn steps