FIELD OF THE DISCLOSURE

The present disclosure relates to a railway bogie for leveling a vertical position of a sensor unit and to a railway vehicle comprising such a railway bogie.

BACKGROUND OF THE DISCLOSURE

Railway vehicles, which are track bound such as trains, trams (streetcars, tramway) or other vehicles often exhibit wheels that are not optimally aligned to the tracks leading to higher friction between the railway track and treads of the wheels. Especially in curves with a small radius, this contact leads to an increased profile wear and noise pollution. In case of low-floor vehicles, this effect is even more pronounced: The low-floor vehicles feature smaller and less wheels per vehicle in order to increase the passenger comfort and inner space of the vehicle by having a continuous low-floor structure. However, this further leads to enhanced loads per wheel and a more pronounced fatigue of the wheel’s material causing smaller rifts or even larger material fractures.

In addition, reducing the number of wheels per vehicle and I or per bogie of the vehicle reduces the suspension comfort of the vehicle and I or of the vehicle comprising the bogie for passengers. In particular, with low floor vehicle this leads to a conflict between inner space requirements and suspension comfort require- merits. Further, creating a desired suspension comfort for the passengers requires conventionally a sophisticated suspension concept arranged above the bogie and between the bogie and the vehicle, which consumes a lot of construction space and further reduces the available inner space for the passengers.

Several attempts are known to reduce the track and wheel wear. In the 1990’s, systems have been developed that were able to steer the wheels in curves. However, it turned out that these solutions often suffered from undesired side effects in straight track sections such that the wheels adhered one-sided with the tread on the track, leading to an enhanced wear and noise in straight track sections. Hence, after a few years, most of these concepts were discarded and conventional concepts combined with wheel-noise absorbers and advanced industrial lubricants were again pursued. A particular challenge was and still is to measure accurately and reliably during operation of the bogie the position of the bogie with respect to the railway track. This is in particular challenging due to suspension movement of a frame of the railway bogie during operation. Sensors for track measurements, which are conventionally arranged rigidly to the frame of the railway bogie move due to the suspension with the frame vertically and laterally, which makes it impossible to provide accurate and reliable measurements, which might be useful for wear reduction.

One example of a railway bogie, which addresses these disadvantages in a successful manner is the WO2018015290 published 2018 in the name of the same applicant. The disclosed vehicle comprises a wheel assembly interconnected to a chassis as well as a method for steering said vehicle. The wheel assembly comprises a cross-member having a first end to which a first hub is interconnected by a first steering joint and a second end to which a second hub is interconnected by a second steering joint. A first wheel is attached to the first hub rotatable around a first rotation axis and a second wheel is attached to the second hub rotatable around a second rotation axis.

SUMMARY OF THE DISCLOSURE

The object of the present disclosure is to provide a railway bogie for a railway vehicle and a railway vehicle comprising the railway bogie. In particular, it is an object of the present disclosure to provide a railway bogie comprising a sensor leveling system for a railway vehicle and a railway vehicle comprising the railway bogie with the sensor leveling system, which do not have at least some of the disadvantages of the prior art.

According to the present disclosure, a railway bogie for leveling a vertical position of a sensor unit is specified. The railway bogie typically comprises a frame and a wheel arranged rotatable with respect to the frame around a respective wheel rotation axis, the wheel is mounted by a swing arm to the frame, wherein the swing arm is pivotable with respect to the frame around a pivot axis against the force of a swing arm spring. In other words, the swing arm provides a damped connection between the wheel and the frame of the railway bogie. The wheel moves during operation of the railway bogie around the pivot axis. This movement is limited and decelerated by the swing arm spring. The swing arm in combination with the swing arm spring provides a suspension for the wheel with respect to the frame, especially for high frequency vibrations coming from the railway track. The railway bogie according to the present disclosure further comprising the sensor unit configured to determine during operation a lateral position of the wheel with respect to a rail, and a sensor leveling system for leveling the vertical position of the sensor unit with respect to the rail due to deflection of the wheel with respect to the frame around the pivot axis during operation of the railway bogie. As described above, the wheel is during operation of the railway bogie deflected around the pivot axis due to its arrangement on the swing arm. This deflection causes vertical movement of all parts arranged rigidly with respect to the swing arm and the wheel. The vertical movement of the sensor unit, which is conventionally rigidly arranged with respect to the wheel, would result in poor quality sensor data of the sensor unit. The sensor leveling system is configured to level the vertical position of the sensor unit with respect to the rail and compensates therefore every movement of the wheel with respect to the rail due to the deflection of the swing arm. The sensor leveling system creates therefore the advantageous possibility that the vertical position of the sensor unit can be kept constant with respect to the rail throughout the operation of the railway bogie. According to the present disclosure, it is therefore possible to get high quality measurement data from the sensor unit during operation of the railway bogie.

Advantageous mounting of the sensor unit on the swing arm is achievable, when the sensor leveling system comprises a sensor bracket configured to position the sensor unit in front of or behind the respective wheel of the railway bogie with respect to a running direction of the wheel, wherein the sensor bracket is arranged pivotable with respect to the swing arm about a leveling axis for adjusting the vertical position of the sensor unit respect to the rail. The sensor bracket is for example arranged parallel to the rail along the lateral inner side of the wheel and extends at least from the leveling axis to the sensor unit for positioning of the sensor unit in front of or behind the respective wheel. Other shapes for the sensor bracket are also conceivable. The pivotable arrangement of the sensor bracket with respect to the swing arm enables an advantageous simple and reliable system for leveling I balancing of the sensor unit arranged on the tip of the sensor bracket due to deflection of the swing arm during operation of the railway bogie. Movement of the sensor bracket around the leveling axis compensates the deflection of the swing arm in an advantageous simple and reliable manner.

In a variation of the present disclosure, the sensor leveling system comprises a leveling actuator coupled to the frame and configured to adjust, by its movement, the vertical position of the sensor unit with respect to the rail during operation of the railway bogie. The sensor unit is for example arranged on the leveling actuator and is arranged vertically displaceable with respect to the frame by movement of the leveling actuator. For example, the sensor unit measures its vertical position with respect to the rail and send an adjustment signal to the leveling actuator in case the measured vertical position does not correspond to a desired vertical position, for example due to suspension movement of the frame. The signal may also be sent by a control unit. The leveling actuator can then adjust the vertical position. A control loop may be implemented for adjusting of the vertical position of the sensor unit during operation.

It is preferred that the leveling actuator is coupled to the sensor bracket and is configured to swivel the sensor bracket around the leveling axis for adjusting the vertical position of the sensor unit with respect to the rail during operation of the railway bogie. According to this embodiment, linear movement of the leveling actuator causes rotation of the sensor bracket around the leveling axis, which enables to adjust I level the vertical position of the sensor unit in front or behind the respective wheel during operation of the railway bogie. This embodiment enables advantageously to use a leveraging solution for the leveling actuator.

It is further preferred that the railway bogie comprises per wheel two leveling actuators, wherein a first leveling actuator is arranged in front of the respective wheel and a second leveling actuator is arranged behind the respective wheel with respect to the running direction, and wherein the two leveling actuators are interconnected for adjusting of the vertical position of the sensor unit. According to this embodiment, the two leveling actuators are connected to the sensor bracket and enable movement of the sensor bracket, which creates an advantageous redundancy. It is further advantageous when both leveling actuators are synchronized with respect to each other for a smooth rotation of the sensor bracket around the leveling axis.

In an embodiment, the sensor leveling system comprises a cross linkage unit interconnecting the first leveling actuator and the second leveling actuator, wherein the cross linkage unit is configured to transfer movement of one of the leveling actuators to movement of the other one of the leveling actuators such that both leveling actuators move simultaneously. The cross linkage unit is for example a control unit, which is configured to harmonize and I or synchronize the movement of the leveling actuators. An advantageous fast and responsive sensor leveling system is feasible, when the first leveling actuator comprises a first fluidic cylinder and the second leveling actuator comprise a second fluidic cylinder. The cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. Each cylinder comprises a first chamber and a second chamber, which are separated by a piston, which is connected to a piston rod, which extends through the cylinder. One longitudinal end of the piston rod is, for example, coupled to the sensor bracket and one longitudinal end of the cylinder is coupled to the frame. The cylinders may use different kind of fluids. The cylinder is an advantageous reliable and simple solution for the leveling actuators of the leveling system. According to this embodiment, the cross linking unit comprises a first fluidic line which is fluidic connected to the first chamber of the first fluidic cylinder and to the second chamber of the second fluidic cylinder, and a second fluidic line which is fluidic connected to the second chamber of the first fluidic cylinder and to the first chamber of the first fluidic cylinder. The different chambers of the two cylinders are cross linked.

The linkage between the different chambers of the two cylinders enables that the sensor bracket and in particular the sensor unit is during operation of the railway bogie kept at the same vertical position. In detail: deflection of the swing arm during operation around the pivot axis causes a movement of the leveling axis. This movement should be compensated by the sensor leveling system, in particular by the fluidic cylinders. The sensor bracket and the sensor unit should be kept static with respect to the rail. It is therefore required that both leveling actuators move simultaneously and in the same direction during deflection of the swing arm. This simultaneous movement is enabled by the cross linking unit according to this embodiment. For example, if the first piston of the first cylinder moves in vertical direction upwards (due to deflection of the swing arm), fluid is moved from the first chamber of the first cylinder to the second chamber of the second cylinder, which causes the second piston of the second cylinder also to move upwards. This upward movement transfers at the same time fluid from the first chamber of the second cylinder to the second chamber of the first cylinder to refill this chamber. The fluid in the system remains during operation constant and flows between the different chambers such that movement of one piston rod is transferred automatically into movement of the other piston rod. This linkage enables an automatic and simultaneous movement of the leveling actuators for leveling of the sensor unit during operation of the railway bogie due to deflection of the swing arm.

It is preferred that, the fluidic cylinders are pneumatic cylinders or hydraulic cylinders. Pneumatic cylinders use (compressed) air as fluid and are advantageously simple to maintain. Hydraulic cylinders use a (compressed) hydraulic oil, like a mineral oil, as fluid and are advantageously reliable, robust and precise. In an embodiment, the fluid pressure is in a range from 10 bar to 50 bar.

It is preferred that, the first fluidic cylinder and the second fluidic cylinder are synchronized cylinders, in which the volume of fluid flowing in and out of the different chambers during operation is constant. Synchronized cylinders comprise, for example, a specific piston rod, which extends throughout the whole cylinder during all operational positions of the piston. Such a specific cylinder may comprise two rods, which extend on both sides of the piston. In this case, the cylinder is a double rod synchronized cylinder. In other words, the volume of fluid flowing in and out of the first and second chamber of one synchronized cylinder is always the same and the piston rod moves in both direction at the same speed. Synchronized cylinders can also be realized with a piston rod arranged only on one side of the piston. In this case, a special shape of the piston rod with internal bores ensures that the surface ratios are the same.

It is preferred that the leveling axis is arranged parallel to the respective wheel rotation axis of the respective wheel. It is therefore possible to advantageously control the movement of the leveling axis due to deflection of the swing arm and to control the vertical position of the sensor unit. In addition, this embodiment provides constructive advantages.

In an embodiment, the first leveling actuator and the second leveling actuator are arranged parallel with respect to each other and I or with respect to a steering axis of the railway bogie, when the sensor leveling system is in zero position. The parallel arrangement with respect to each other enables a precise and reliable simultaneous movement of the leveling actuators. During operation, the leveling actuators may rotate at a small angel, with respect to their connection to the frame, due to the deflection of the swing arm. The steering axis is, for example arranged laterally between two wheels of the railway bogie. The zero position or neutral position is the position of the railway bogie in a dormant I neutral state, e.g. without any movement.

It is preferred that, the first leveling actuator and the second leveling actuator are arranged equidistantly away from the leveling axis with respect to the running direction of the respective wheel. According to this embodiment, it is possible to use the same leveling actuators for both sides. In case the distance from the leveling axis to the leveling actuators is not equidistant, it is necessary to have different leveling actuators, for example with different chamber sizes, to enable the required leveling of the vertical position of the sensor unit using the cross linkage unit.

In an embodiment, at least one of the leveling actuators, preferably both, is/ are coupled to a base frame of the frame of the railway bogie. The base frame is, with respect to its vertical position, configured to be rigidly coupled I connected to the railway vehicle. The railway vehicle is arranged substantially parallel with respect to the rail. Connecting one longitudinal end of the leveling actuators to the base frame advantageously enables that these ends of the leveling actuators are arranged parallel with respect to the rail during operation of the railway bogie.

In a variation of the present disclosure, the wheel comprises at least one of the sensor units arranged in front of and I or behind each wheel, and wherein the wheel comprises the sensor leveling system for leveling the vertical position of the sensor unit with respect to the rail due to deflection of the wheel with respect to the frame around the pivot axis during operation of the railway bogie. It is preferred that the sensor bracket extends in front of the respective wheel and behind the respective wheel for positioning two sensor units, one in front of the wheel and one behind the wheel. By leveling the sensor bracket, the vertical position of both sensor units is kept constant during operation of the railway bogie. Two sensor units per wheel increase the data quality, which helps to increase the accuracy of the determination of the position of the wheel with respect to the rail. In a further embodiment, each wheel of the railway bogie comprises two sensor units, a front sensor unit, arranged in front of the wheel, and a back sensor unit, arranged behind the respective wheel. The front sensor unit and the back sensor unit are used to determine the lateral position of the wheel with respect to the rail and in addition a tangential position of the wheel with respect to the rail. The tangential position determines the orientation of the running direction of the wheel, in particular the running direction of the wheel tread and wheel flange, with respect to the rail.

In a further embodiment, the sensor unit comprises a first sensor configured to provide a first sensor signal, corresponding to the lateral position of the sensor unit with respect to the rail, in particular with respect to an essentially vertical flange of the rail, and a second sensor configured to provide a second sensor signal, corresponding to the vertical position of the sensor unit with respect to the rail, in particular to an essentially horizontal surface of rail.

Advantageous accurate measurement results are achievable when the distance between the sensor unit and the essentially horizontal surface of the rail is in a range from 25 mm to 5 mm. The accuracy I performance of the sensor signal depends on the distance of the sensor unit to the rail. The preferred distance depends on the sensor type and / or sensor requirements.

Advantageous positioning of the first sensor with respect to the second sensor is achievable when the first sensor and the second sensor are in lateral direction spaced apart with respect to each other. This positioning reflects additionally the orientation of the essential vertical flange of the rail and the essential horizontal surface of the rail and is therefore advantageous for an accurate measurement.

Improvement of the sensor signal quality and therefore the accuracy of the measurement of the sensor unit is achievable when the first sensor is configured to be positioned during operation substantially above the essentially vertical flange of the rail, preferably above a guiding flange of the rail, and wherein the second sensor is configured to be positioned during operation substantially above the essentially horizontal surface of the rail, preferably above a running surface of the rail. The guiding flange of the rail is the vertical flange of the rail, which is configured to be in contact with an essentially vertical flange of the wheel for guiding of the wheel on the rail. The running surface of the rail is the surface, which is configured to be in contact with a running surface of the wheel, or a tread of the wheel. Positioning of the first sensor and the second sensor according to this embodiment improves therefore the signal quality, in particular because these surfaces of the rail are configured to be in contact with the wheel and have advantageous smooth surface properties.

In an embodiment, the railway bogie further comprises a housing configured to at least partially comprise I contain the sensor unit. The housing is, for example, a bar which is arranged between the sensor unit and the sensor bracket and on which the sensor unit is arranged. The housing has in another embodiment a cavity, which houses I comprises at least one of the sensors or the entire sensor unit. The housing advantageously protects the sensor unit from mechanical damage during operation. It is preferred that, the railway bogie comprises at least one shim arranged between the sensor unit, preferably between the housing, and the sensor bracket and configured for adjusting the vertical position of the sensor unit with respect to the rail. The shims are, for example, spacers, which are stacked and which are placed between the sensor unit and the sensor bracket. It is possible to adjust the vertical position of the sensor unit by removing or adding one or more shims(s). Wear of the wheels may cause a change in wheel diameter, which causes a change in the vertical position of the respective sensor unit. Removing at least one shim enables to adjust the vertical position back to the original value in a reliably and simple manner.

In a further variation, the sensor leveling system comprises a lever mechanism coupled to the frame and configured to adjust, by its movement, the vertical position of the sensor unit with respect to the rail during operation of the railway bogie. The lever mechanism may be an alternative for the sensor actuators for adjusting the vertical position of the sensor unit. The lever mechanism may comprise one or several levers, enabling to adjust the vertical position of the sensor unit (in other words to keep the sensor unit static with respect to the rail during operation), even if the frame of the railway bogie moves up and down due to deflections of the suspension system of the railway bogie. Moving levers are advantageously reliable, simple and do not require a hydraulic fluid, which improves the overall handling and the maintainability of the sensor leveling system. It is conceivable that the railway bogie comprises for each wheel the lever mechanism as sensor leveling system. It is preferred that the lever mechanism is coupled to the sensor bracket and is configured to swivel the sensor bracket around the leveling axis for adjusting the vertical position of the sensor unit with respect to the rail during operation of the railway bogie. The lever mechanism may be configured to deflect the sensor bracket during operation of the railway bogie such that the vertical position of the sensor unit with respect to the railway system is kept static. A deflection of the swing arm or the frame during operation is advantageously compensated by the lever mechanism such that the vertical position of the sensor unit is kept static or constant.

The lever mechanism comprises in a preferred variation a first lever and a second lever both connecting the frame and the sensor bracket. The first and the second levers are for example connected to the frame and the sensor bracket via respective joints, preferably joints enabling rotary movement and linear movement of the levers in one specific direction, preferably along the running direction of the railway bogie.

It is preferred that the first lever and the second lever are rotatable connected with each other via a central joint and that the four connection point between the levers and the frame and the sensor bracket enable a rotary movement of the levers with respect to the frame and the sensor bracket. It is further preferred that three of the four connection points enable linear displacement of these connecting points with respect to the frame and the sensor bracket respectively.

An advantageous lever mechanism is realizable when the first lever and the second lever are rotatable connected with each other via a central joint and wherein the first lever or the second lever is rigidly connected to the frame and the other lever is arranged linearly displaceable on the frame, and wherein the first lever and the second lever are arranged linearly displaceable on the sensor bracket, preferably with respect to the running direction of the railway bogie. Such a lever mechanism forms a so-called scissors lever, enabling advantageously to adjust the position of the pivotable arranged sensor bracket, such that the sensor unit is arranged at the same vertical position with respect to the rail during operation of the railway bogie even if the frame is deflected. The central joint is for example arranged substantially central above the leveling axis of the sensor bracket, the levers form an X and their ends are connected (displaceable) to the frame and the sensor bracket. One end of the first lever is for example rigidly connected to the frame behind the leveling axis of the sensor bracket with respect to the running direction and the other end of the first lever is for example displaceable connected with the sensor bracket in front of the leveling axis with respect to the running direction. Further, one end of the second lever is for example rigidly connected to the frame in front of the leveling axis with respect to the running direction and the other end of the second lever is for example displaceable connected with the sensor bracket behind the leveling axis with respect to the running direction.

It is further preferred that the railway bogie enables the linear displacement via a rod arranged at the frame and I or the sensor bracket respectively and via sleeves arranged on respective longitudinal ends of the first lever and the second lever, wherein the sleeves are arranged coaxially and displaceable with respect to the rods. For example, a first linear bearing is formed by the frame and the displaceable arranged lever enabling the movement of the respective lever with respect to the frame, and a second linear bearing formed by the sensor bracket and the first lever and the second lever enabling the movement of the first lever and the second lever with respect to the sensor bracket.

It is advantageous when the first linear bearing and I or the second linear bearings are formed via the rod arranged at the frame and I or the sensor bracket respectively and via the sleeve arranged on the respective longitudinal ends of the first lever and the second lever. The rods are for example arranged at the frame and the sensor bracket extending parallel with respect to each other (in neutral position of the railway bogie) and extending preferably parallel to the railway track. The sleeves are preferably connected to the longitudinal ends of the levers via a joint, which enables rotation between the lever and the sleeve. One sleeve is for example rigidly connected to the rod realizing the rigid connection between the lever and the frame. This rigidly connected lever is also advantageously connected via a joint to the respective sleeve, enabling the required rotary movement of the rigidly connected lever.

In a further variation, the sensor leveling system comprises a mechatronic mechanism, which is configured to adjust the vertical position of the sensor unit such that the distance between the sensor unit and the rail is kept constant during operation of the railway bogie. The mechatronic mechanism comprises for example an electrical controlled actuator for adjusting the vertical position of the sensor unit. Further, the mechatronic mechanism may comprise a sensor, which provides a signal, which is used to control the mechatronic mechanism in order to adjust the vertical distance of the sensor unit. The sensor is for example configured to measure a corresponding distance, angle or deflection, which is characteristic for the respective deflection of the wheel during operation, wherein the sensor signal is processed such that a respective control signal is used to control the mechatronic mechanism, in particular the at least one actuator for leveling the vertical position of the sensor unit during operation.

In a further aspect, a sensor leveling system for leveling a vertical position of a sensor unit of a railway bogie is specified. The sensor leveling system is configured for leveling the vertical position of the sensor unit with respect to a rail due to deflection of a wheel of the railway bogie with respect to the frame around a pivot axis during operation of the railway bogie. The sensor leveling system may comprise the features with its respective advantages as described above and hereinafter with respect to the other aspects and embodiments of the present disclosure.

In a further aspect of the present disclosure, a railway vehicle is specified, which comprises the railway bogie as described above and hereinafter.

It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

The herein described disclosure will be more fully understood from the detailed description given herein below and the accompanying drawings, which should not be considered limiting to the disclosure described in the appended claims. The drawings are showing:

Fig. 1 a perspective view of a first variation of the railway bogie according to the disclosure;

Fig. 2 a first perspective view of a second variation of the railway bogie according to the disclosure; Fig. 3 a second perspective view of the second variation of Fig. 2;

Fig. 4 a detailed view of Fig. 3;

Fig. 5 a first section view through the railway bogie according to the second variation;

Fig. 6 a second section view through the railway bogie according to the sec- ond variation;

Fig. 7 a detailed view of Fig. 6;

Fig. 8 a schematic view of a sensor leveling system according to a first variation; Fig. 9 a schematic view of movement of the railway bogie during operation according to a first variation;

Fig. 10 a side view of the railway bogie according to a third variation;

Fig. 11 a detailed view of the sensor leveling system according to the third variation.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

Figure 1 shows a perspective view of a first variation of the railway bogie according to the disclosure. Figure 2 shows a first perspective view of a second variation of the railway bogie according to the disclosure. Figure 3 a second perspective view of the second variation of Figure 2. Figure 4 shows a detailed view of Figure 3. Figure 5 shows a first section view through the railway bogie according to the second variation. Figure 6 shows a first section view through the railway bogie according to the second variation. Figure 7 shows a detailed view of Figure 6. Figure 8 shows a schematic view of a sensor leveling system according to a first variation. Figure 9 shows a schematic view of movement of the railway bogie during operation according to a first variation.

As e.g. visible in Figures 1, 2, 3, 5 and 6, a railway bogie 1 comprises a base 2, which is configured to be attached to a chassis of a railway vehicle. The base 2 may be connected to a connecting part 9, which is configured to be connected to the chassis of the railway vehicle during operation of the bogie 1 . The bogie 1 further comprises a frame 3 arranged rotatable with respect to the base 2 around a vertical steering axis 4. The bogie 1 further comprises two wheels 5, which comprise a tread 6. The tread 6 or tread profile is the radially external portion of the wheel 5. The tread 6 comprises a contact surface or a rolling surface, which is, during operation, in contact with a running surface of a rail 32 of a railway track 31 . The wheels 5 are arranged rotatable with respect to the frame 3 around a respective wheel rotation axis 7. The wheel rotation axis 7 of the wheels 5 are arranged essentially coaxially to each other and the steering axis 4 is arranged in a lateral direction Y between the two wheels 5. In another variation, the wheel rotation axis 7 may be arranged at a specific angle with respect to the lateral direction Y. In this case, the wheel rotation axis 7 are inclined with respect to the lateral direction Y. Figure 1 further shows covers 30 arranged on the frame 3 for protection of the bogie 1 during operation.

The Figures further show that the frame 3 comprises a base frame 23 and a wheel frame 24. The base frame 23 is arranged mainly above the wheel frame 24. The base frame 23 is interconnected to the wheel frame 24 via a spring damping system 12 and vice versa. The spring damping system 12 comprises a spring assembly 26 with a first spring 27 and a second spring 28. A strut 29 is arranged between the base frame 23 and the wheel frame 24.

The bogie 1 further comprises a sensor arrangement 11 , best visible in Figures 3, 4 and 7, which is configured to determine during operation the lateral position of at least one of the wheels 5 with respect to the rail 32 of the railway track 31 . The sensor arrangement 11 enables to determine the position of the wheels 5 on the railway track 31 during operation, which is crucial to control the position of the treads 6 of the wheels 5 with respect to the railway track 31 for noise and wear control/reduction and to steer the railway bogie 1 during operation for an advantageous noise and wear control I reduction.

Figure 1 further shows a steering actuator 16, which is connected to the frame 3 and to the connecting part 9. Movement of the steering actuator 16 cause a rotation of the frame 3 around the steering axis 4 by a steering angle with respect to the base 2 and with respect to the connecting part 9 and also with respect to the chassis of the railway vehicle.

Figures 3, 4 and 7 further show the sensor arrangement 11 in detail. The sensor arrangement 11 comprises a front sensor unit 13 arranged in front of the respective tread 6 of the wheel 5 with respect to a running direction X of the bogie 1 . The sensor arrangement 11 further comprises a back sensor unit 14 arranged behind the respective tread 6 of the wheel 5 with respect to the running direction X of the bogie 1 . As best visible in Figure 3, both wheels 5 of the railway bogie 1 comprise the front sensor unit 13 and the back sensor unit 14. The Figures 3, 4, 5, 6, 7, 8 and 9 further show a sensor leveling system 43, which is configured to level a vertical position 41 of a sensor unit 35 (14, 15) with respect to the rail 32 due to deflection of the wheel 5 with respect to frame 3 around a pivot axis 21 during operation of the railway bogie 1 . The pivot axis 21 is arranged in front of or behind the respective wheel rotation axis 7 with respect to the running direction X. The sensor leveling system 43 according to the embodiment as shown in the Figures comprises a sensor bracket 15, which is mounted pivotable with respect to the wheel 5, in particular to the swing arm 20, and which positions the front sensor unit 13 and the back sensor unit 14 in front of and behind the wheel 5. As best visible in Figure 7 and 9, the sensor bracket 15 extends parallel to the rail 32 and is arranged pivotable around the leveling axis 10. The sensor bracket 15 extends along the wheel 5 and holds the respective sensor units 13, 14 at a predefined position during operation of the railway bogie 1. The sensor leveling system 43 further comprises two leveling actuators 8, best visible in Figures 5 and 6, which are connected to the frame 3 and to the respective sensor bracket 15. Linear movement of the leveling actuators 8 adjusts during operation of the bogie 1 the vertical position 41 of the front sensor unit 13 and of the back sensor unit 14 with respect to the railway track 31 . Movement of the frame 3, in particular movement of a swing arm 20 of the frame 3 and movement of the suspension system of the frame 3, which affects the vertical position 41 of at least one of the sensor units 13, 14, can be compensated by movement of the leveling actuators 8. The leveling axis 10 is arranged parallel with respect to the respective wheel rotation axis 4 and on the same vertical virtual plane as the wheel rotation axis 4. The Figures further show that an additional bracket is arranged between the swing arm 20 and the sensor bracket 15. The additional bracket is, according to the embodiment as shown in the Figures, rigidly arranged on the swing arm 20, best visible in Figure 7. The additional bracket positions the leveling axis 10 vertically below the wheel rotation axis 7.

According to the variation of the disclosure as shown in the Figures, the linear movement of the leveling actuators 8 causes pivoting of the connected sensor bracket 15 around the leveling axis 10. The pivoting around the leveling axis 10 compensates a possible deflection of the swing arm 20 against a swing arm spring 22 during operation of the railway bogie 1 , such that the vertical position 41 of the respective sensor units 13, 14 may stay as static as possible during operation of the railway bogie 1 . In another variation of the disclosure, each of the leveling actuators 8 are connected with one of the sensor units 13, 14 and may move independently, such that each of the sensor units 13, 14 is always at the predefined vertical position 41 due to individual movement of the leveling actuators 8.

The Figures 1 to 4 further show that each wheel 5 comprises an electrical engine 18 and a brake 19. The electrical engine 18 is configured to drive, if required, during operation the respective wheel 5, and the brake 19 is configured to decelerate, if required, during operation of the railway bogie 1 the respective wheel 5. The brake 19 is a disk brake and the disk of the disk brake is arranged on the same shaft as the respective wheel 5 and the respective electrical engine 18. The wheel 5, the electrical engine 18 and the disk are partially surrounded and held by the swing arm 20, best visible in Figure 3. A brake caliper of the brake 19 is arranged on the swing arm 20.

The Figures further indicate schematically a control unit 17. The control unit 17 is, for example arranged within the railway bogie 1 or at a different position of the railway vehicle. The control unit 17 is configured to receive, during operation of the bogie 1 , a first sensor signal 38 from a first sensor 36 of the sensor unit 35 and the second sensor signal 39 from a second sensor 37 from the sensor unit 35. The first sensor signal 38 corresponds, according to this embodiment, to a lateral position 40 of the sensor unit 35 with respect to a substantial vertical flange 33 of the rail 32, and the second sensor signal 39 corresponds to the vertical position 41 of the sensor unit 35 with respect to a horizontal surface 34 of the rail 32.

The Figures further show that the railway bogie 1 further comprises a plurality of shims 44 arranged between the sensor unit 31 I sensor housing 42 and the sensor bracket 15 and configured for adjusting the vertical position 41 of the sensor unit with respect to the rail. The shims 44 are, for example, spacers, which are stacked and which are placed between the sensor unit 35 and the sensor bracket 15.

Figure 8 shows schematically a detail of the sensor leveling system 43. Figure 8 shows the two leveling actuators 8 and a cross linkage unit 45, which interconnects the two leveling actuators 8. The two leveling actuators 8 as shown in the Figures are fluidic (for example hydraulic or pneumatic) cylinders. The first lev- eling actuator 8 comprises a first fluidic cylinder 46 and the second leveling actuator 8 comprises a second fluidic cylinder 47. Each of the cylinder 46, 47 comprises a first chamber 48 and a second chamber 49, which are separated by a piston 52. The piston 52 is connected to a piston rod 53, which extends throughout the first and the second chamber 48, 49. One longitudinal end of the piston rods 53 is connected to sensor bracket 15 and one longitudinal end of the cylinders 46, 47 is connected to the frame 3 (best visible in Figure 7). Figure 8 further shows the cross linkage unit 45 in detail. The cross linkage unit 45 comprises a first fluidic line 50, which is connected to the first chamber 48 of the first cylinder 46 and to the second chamber 49 of the second cylinder 47. The cross linkage unit 45 further comprises a second fluidic line 51 , which is connected to the second chamber 49 of the first cylinder and to the first chamber 48 of the second cylinder 47. Figure 8 further shows schematically inlets 54 and outlets 55 for the fluid of the sensor leveling system 43, which are used to fill and to release fluid into I out of the system. The setup as shown in Figure 8 results in a simultaneous and constant movement of both actuators 8. For example, when one piston rod 53 moves upwards, due to a deflection of the swing arm 20 during operation of the railway bogie 1 , the fluid from the corresponding first chamber 48 will be pressed into the second chamber 49 of the second cylinder 47. This results in upwards movement of the piston rod 53 of the second cylinder 47, which will press fluid from the first chamber 48 of the second cylinder 47 to the first chamber 49 of the first cylinder 46. As shown in the Figures, both cylinders 46, 47 have the same size, such that movement of one piston rod 53 results in the same movement (velocity and distance) of the other piston rod 53. Figure 9 shows schematically the different movements within the railway bogie 1 during operation. As can be seen in the Figure 9, the base frame 23 is arranged parallel with respect to the rail 32 during operation of the railway bogie 1 , nevertheless the base frame 23 may move in vertical direction Z due to the suspension of the railway bogie 1 . The wheel 5 remains, during operation of the railway bogie 1 , in contact with the rail 32. The positioning difference between the base frame 23 and the wheel 5 during operation is compensated by the swing arm 20 and the swing arm spring 22. The swing arm 20 rotates slightly around the pivot axis 21 against the force of the swing arm spring 22. If the sensor bracket 15 would be arranged rigidly on the swing arm 20, the sensor bracket 15 would follow the rotation of the swing arm 20. In this case the vertical position 41 of the sensor unit 35, arranged in front of or behind the wheel 5 would also change, which would result in poor sensor data quality. The Figures and in particular Figure 9 show that the sensor bracket 15 is arranged pivotable on the swing arm 20 around the leveling axis 10. Further, the Figures show that the leveling actuators 8 are coupled to the sensor bracket 15 and the base frame 23. Simultaneous and equal movement of both actuators 8 compensates the rotational movement of the swing arm 20 such that the sensor bracket 15 and the thereto attached sensor units 35 are kept at the same vertical position 41 during operation of the railway bogie 1 . In other words, parallel movement of the two actuators 8 compensate the rotational movement of the swing arm 20 around the pivot axis 21 such that the vertical position 41 of the sensor unit(s) 35 is kept constant during operation of the railway bogie 1 .

According to the present disclosure, it is possible to maintain the vertical known height arrangement of the sensor units 35 with respect to the rail 32. The sensor leveling system 43 enables the sensor units 35 to always stay parallel to the rail 32, even when faced with any movements or vibrations from the primary suspension system of the railway bogie 1 or faced with any movements of the swing arm 20. The sensor levelling system 43 allows the sensor units 35 to maintain a constant parallelism above the rail 32, even with any physical movements from the suspension of the railway bogie (distance, rolling, pitching, and yawing movements).

An important aspect is the cross linking of a forward located leveling actuator 8 in combination with a rear located leveling actuator 8. The relative movement of one actuator 8 will directly affect the other actuator 8 as described above.

The mechanical connection positions (on the frame 3 and on the sensor bracket 15) determine how the relative extensions and retractions function. The sensor levelling system 43 consists of three major portions as best visible in Figure 7. First the connection of the leveling actuators 8 to the frame 3, second the leveling actuators 8 and third the sensor bracket 15 arranged pivotable around the leveling axis 10. The connection of the leveling actuators 8 to the frame 3 determines the parallel position of the sensor bracket 15. The leveling actuators 8 are fixed to the base frame 23 of the frame 3.

The leveling actuators 8 in combination with the cross linkage unit 45 accounts for any compression or decompression of the suspension created by vertical movements of the wheel rotation axis 7. The sensor levelling actuators 8 are cross linked, in combination with the centralized sensor levelling rotation point (leveling axis 10) therefore any vertical movement of the wheel 5 will not affect the parallel orientation of the sensor bracket 15 (sensor units 35) relative to the rail 32.

The sensor bracket 15 is fixed through leveling axis 10 that is attached to the central vertical line of the wheel rotation axis 7.

The Figures 10 and 11 show a third variation of the railway bogie 1 according to the present disclosure. This railway bogie 1 comprises a different sensor leveling system 43 compared to the variation shown with respect to the previous described figures. The sensor leveling system 43 comprises a lever mechanism 56, which is configured to adjust the vertical position of the at least one sensor unit 35 during operation of the railway bogie 1 with respect to the railway track 31 . The lever mechanism 56 as shown in the figures comprises a first lever 57 and a second lever 58, which are both connecting the frame 3 with the sensor bracket 15. The first lever 57 and the second lever 58 are further rotatable connected via a central joint 59 with respect to each other. The levers 57, 58 form the shape of an X with the central joint 59 in the central crossing point. It is further visible that the first lever 57 and the second lever 58 are arranged linearly displaceable on the railway bogie 1 thereby enabling the required compensation of movement of the frame 3, in particular of the swing arm 20 with respect to the sensor bracket 15. The first lever 57 and the second lever 58 are connected to the frame 3 and the sensor bracket 15 such that a rotary movement between the levers 57, 58 and the frame 3 and the sensor bracket 15 is enabled at all connecting points. The embodiment of the figures show that the first lever 57 is arranged rigidly on the frame 3 of the railway bogie 1 via its first longitudinal end (still enabling rotary movement of the first lever 57 with respect to the frame 3). The other longitudinal end of the first lever 57 is arranged linearly displaceable at the sensor bracket 15. The second lever 57 is arranged linearly displaceable at the frame 3 via its first longitudinal end and linearly displaceable at the sensor bracket 15 via its second longitudinal end. The second lever 57 is arranged on the frame 3 and the sensor bracket 15 such that the rotary movement is enabled. The rotatable connected first lever 57 and the second lever 58 form a so called scissors lever, which enables due to its respective connection with the frame 3 and the sensor bracket 15 that the sensor bracket 15 is kept vertically aligned, due to pivoting the sensor bracket 15 around the leveling axis 10, with the rail 32 during operation of the railway bogie 1 even if the swing arm 20 with the wheel 5 deflects, with respect to the frame 3 due to suspension requirements.

The required lateral movement of the longitudinal ends of the first and the second levers 57, 58 is in this embodiment realized via linear bearings 60, 61. A first linear bearing 60 is arranged between the frame 3 and the second lever 58. Second linear bearings 61 are arranged the sensor bracket 15 and the first lever 57 and the second lever 58. In this embodiment as shown in the Figures 10 and 11 , the linear bearing 60, 61 is realized via a rod 62 and sleeve 63 combination, wherein the sleeve 63 is axially displaceable with respect to the rod 62. The figures show that one rod 62 is arranged rigidly at the frame 3, via mounting brackets 64. Another rod 62 is arranged rigidly at the sensor bracket 15, preferably parallel with respect to the main extension direction of the sensor bracket 15. Each longitudinal end of the levers 57, 58 is connected to one of the sleeves 63, which are arranged coaxially with respect to the respective rods 62. The first sleeve 63, which connects the first lever 57 with the frame 3 is arranged rigidly on the rod 62, via screws or stops or any other fixing mechanism. The other sleeves 63 are arranged axially displaceable with respect to the rods 62, such that a vertical distance reduction or extension is realizable between the frame 3 and the sensor bracket 15, enabling that the sensor bracket 15 is kept at the desired level position with respect to the rail 32 during operation of the railway bogie 1 . Other linear bearings, e.g. via lanes are also conceivable. In the embodiment as shown in the figures, the rods 32 are arranged parallel with respect to the running direction of the railway bogie 1 . The figures further show that the rotary movement between the levers 57, 58 and the frame 3 and the sensor bracket 15 is realized via joints, which connect the longitudinal ends of the levers 57, 58 with the sleeves 63. The joints are for example realized via shafts arranged between the levers 57, 58 and the sleeves 63.

The lever mechanism 56 enables that a deflection of the swing arm 20 around the pivot axis 21 during operation of the railway bogie 1 does not affect the vertical positon of the sensor unit 35. In other words, the lever mechanism 56 is config- ured to compensate the deflection of the swing arm 20 by movement of the lever mechanism 56 such that the sensor bracket 15 is kept horizontally aligned with respect to the rail such that the distance between the sensor unit 35, arranged e.g. at the tip of pivotable arranged sensor bracket 15.

LIST OF DESIGNATIONS

1 Railway bogie 25 Damper

2 Base 26 Spring assembly

3 Frame 27 First spring

4 Steering axis 28 Second Spring

5 Wheel 29 Strut

6 Tread 30 Cover

7 Wheel rotation axis 31 Railway track

8 Leveling actuator 32 Rail

9 Connecting part 33 Vertical flange

10 Leveling axis 34 Horizontal surface

11 Sensor arrangement 35 Sensor unit

12 Spring damping system 36 First sensor

13 Front sensor unit 37 Second sensor

14 Back sensor unit 38 First sensor signal

15 Sensor bracket 39 Second sensor signal

16 Steering actuator 40 Lateral position

17 Control unit 41 Vertical position

18 Electrical engine 42 Housing

19 Brake 43 Sensor leveling system

20 Swing arm 44 Shim

21 pivot axis 45 Cross linkage unit

22 Swing arm spring 46 First fluidic cylinder

23 Base frame 47 Second fluidic cylinder

24 Wheel Frame 48 First chamber 49 Second chamber

50 First fluidic line

51 Second fluidic line

52 Piston

53 Piston rod

54 Inlet

55 Outlet

56 Lever mechanism

57 First lever

58 Second lever

59 Central joint

60 First linear bearing

61 Second linear bearing

62 Rod

63 Sleeve

64 Mounting brackets

X running direction

Y lateral direction

Z vertical direction