Active steering of a rail-mounted two-axle working vehicle

Abstract

In a rail-bound, two-axle work vehicle (1), comprising a frame (2) and a superstructure (3), and a chassis (4) having two wheels (8) rotatable about a common axis of rotation, wherein the chassis (4) is pivotably mounted about a vertical axis, such that the chassis (4) together with the wheels (8) can be pivoted about the vertical axis at a steering angle when the work vehicle (1) is traveling around a curve following the course of the rails (9), the invention proposes: • that an actuator is effectively connected to the chassis (4) in such a way that different movements of the actuator cause the chassis (4) to pivot into different positions about its vertical axis, • and that a control unit is provided which is effectively connected to the actuator for signal transmission, such that, based on control signals transmitted to the actuator by the control unit, a movement of the actuator and thus the steering position of the chassis (4) can be controlled.

Description

[0001] The invention relates to a method for manufacturing a rail-bound two-axle work vehicle. By means of a pivotable bearing of the work vehicle's axle, the axle is steerable, so that when the work vehicle is traveling around a curve, the chassis can automatically align itself as optimally as possible with the rails in order to follow the rail's curve optimally and thereby avoid undesirable friction, so-called "abrasion", and the associated mechanical wear as well as any associated noise emissions.

[0002] The following vehicles are considered non-rail vehicles in this context: Firstly, rail vehicles in which several wheels or axles are combined into bogies are considered non-rail vehicles. The present proposal concerns a so-called two-axle work vehicle. Within the context of this proposal, "two-axle" means that the work vehicle has two separate axles – not combined into a bogie. Accordingly, at least these two separate axles are provided below the typically provided vehicle frame or superstructure, and possibly one or more additional axles. The problem described at the beginning does not occur with bogies with regard to cornering behavior.

[0003] Secondly, rail vehicles that are not work vehicles, but rather, for example, transport vehicles or passenger vehicles, are not considered railway vehicles. Within the scope of this proposal, "work vehicles" refers to vehicles intended for track maintenance, such as laying overhead contact lines, tamping the track bed, resurfacing the rail profile, or similar tasks. The aforementioned transport or passenger vehicles travel at relatively high speeds on the rails during normal operation – that is, in their typical use. Work vehicles, on the other hand, travel at considerably lower speeds during normal operation, for example, at working speeds of less than 20 km / h, or possibly at walking speed.Regarding cornering behavior, the low speed of the work vehicles presents a problem: for example, when driving through a banked curve, they risk sliding towards the lower inside of the curve, as the bank is designed for a specific speed of freight or passenger trains, which is significantly higher than the work vehicle's normal operating speed. Therefore, the problem described at the beginning does not occur with vehicles other than work vehicles.

[0004] Vehicles of this type are known from practical experience. The closest prior art is considered to be European patent application EP 0 937 818 A2, which describes a track maintenance vehicle with an excavator superstructure. Such vehicles typically have undercarriages whose wheelsets each have two running wheels rotatable about a common axis of rotation and pivotally mounted about a vertical axis, so that the undercarriage, together with the running wheels, can be pivoted, i.e., deflected, around the vertical axis when the vehicle is cornering. It automatically follows the track alignment solely due to the forces acting upon it and the resulting equilibrium of forces. This automatic steering has proven particularly effective in practice for large curve radii. However, when negotiating smaller curve radii, it is often not possible to ensure that the undercarriage executes the required steering deflection.

[0005] The pivoting axle suspension allows the chassis to steer, a function that can be described as passive steering: when cornering, so-called deflection forces from the track act on the wheels of the axle, causing the chassis to pivot automatically around its vertical axis, so that the two wheels of the axle follow the curved track. Through restoring forces, the axle suspension essentially ensures automatic centering of the chassis, which is advantageous for straight-line travel. The deflection forces acting on the axle when cornering, which displace the chassis from its centered position, must therefore overcome the restoring forces that strive to achieve automatic centering.

[0006] As vehicle weight increases, so too can the restoring forces. This affects, for example, a work vehicle that is equipped with different tools or loaded with different materials depending on its use, meaning the same work vehicle can have different operating weights. And this, of course, affects different types of work vehicles, which inherently have different vehicle weights. Furthermore, the deflection forces can also vary in magnitude, even when acting on the same, unchanged work vehicle: for example, weather conditions, such as humidity, can alter the friction between the wheel and the rail, leading to correspondingly different deflection forces.

[0007] The aforementioned influences cause very different and variable force ratios between, on the one hand, the deflection forces and, on the other hand, the restoring forces.

[0008] In particular, but not exclusively, this proposal concerns a rail-bound, two-axle work vehicle in which the undercarriage is mounted or suspended by shackle suspension. A typical characteristic of shackle suspension is that the restoring forces increase considerably with increasing vehicle weight, thus significantly influencing the force ratio between the deflection forces and the restoring forces.

[0009] In practice, it has been observed that passively steered, pivotally mounted axles of a rail-bound two-axle work vehicle are only partially deflected during an undesirably high proportion of cornering maneuvers. This ranges from a present but incomplete steering angle to an axle remaining in its centered position and not deflected at all in the curve.

[0010] From WO 97 / 41022 A1, a rail vehicle with a single-axle running gear is known, in which a sensor unit is influenced by the curve radius of a track to be traversed and serves to control an actuating unit which in turn is coupled to the running gear in order to pivot it about a real or virtual vertical axis.

[0011] From EP 3 012 170 A1, a bogie for a rail vehicle is known which, through its pendulum-like movement, enables the wheels to run in a sinusoidal motion on the rails. This avoids increased wear of the rails, limited to a narrow section of the rail profile, in favor of more even wear and a correspondingly longer service life.

[0012] From DE 1 215 192 B, a device for curve-adapted control of single- or multi-axle bogies of rail vehicles is known, the bogies of which are pivotable about a vertical axis, namely in the horizontal plane, wherein pneumatic springs are provided for this purpose, the filling quantities of which are adjustable according to the curve curvature. Contact sensors on the rail influence sensing elements of the bogies in order to generate control impulses for the control elements, which act on the gas spring bellows.

[0013] The present proposal is based on the task of ensuring optimized axle deflection when cornering in a rail-bound two-axle work vehicle.

[0014] This problem is solved by a method according to claim 1. Advantageous embodiments are described in the dependent claims.

[0015] The proposed system envisages that the axle is not only passively steered by the forces exerted on the wheels by the track, but also actively deflected from its centered position by one or more actuators when the work vehicle negotiates a curve. Two essential components are proposed for this purpose: First, at least one actuator that can act on the axle, allowing it to be deflected from its centered position and pivoted around its vertical axis, thus enabling active steering and the assumption of a predetermined steering angle. For this purpose, the actuator is effectively connected to the axle, acting either directly on the axle or indirectly on a component connected to the axle, so that ultimately, a movement of the actuator produces the desired steering movement of the chassis.

[0016] Secondly, a control system is provided that controls the actuator, thus determining its movements and consequently the position assumed by the axis.

[0017] The specific technical design can be achieved by using a single actuator connected to a centrally located guide element of the axle, thus causing a pivoting movement of the axle around its vertical axis, depending on the actuator's movement. To manufacture a work vehicle, such as the one described above, it may be possible to modify a previously used axle suspension design only minimally by adding the aforementioned actuator to an existing component. This offers an economic advantage in the production of the work vehicles because they can be manufactured either with or without the actuator, and because manufacturing the work vehicle with the actuator requires very few modifications compared to the previously standard production method without it.From a technical perspective, it is advantageous that even work vehicles already in operation can be retrofitted and designed according to the proposal by replacing the corresponding element of the axle suspension, so that the advantages of the present proposal can be used with minimal effort even for work vehicles that were not originally equipped accordingly.

[0018] For example, if hydraulic cylinders are used as actuators, a double-acting cylinder can be used, which can act on the connected component by both pressure and tension. However, instead of a single such actuator, two oppositely arranged, single-acting cylinders can also be used, each acting, for example, only in pressure, so that two different directions of movement can be achieved by selectively actuating one or the other cylinder.

[0019] Advantageously, the actuator can incorporate an electric drive motor, ensuring a mechanically robust and leak-proof design. Such an electric actuator can, for example, be designed as a spindle drive or a rack and pinion drive, thus featuring a longitudinally movable push or pull element whose movement can be transmitted directly or indirectly to the axis.

[0020] Alternatively - or possibly in addition to the above-mentioned designs and installation of actuators, namely to support them and to keep the forces to be applied as low as possible - it may be possible to arrange one actuator on each side of the axle, i.e., assigned to each of the two wheels.

[0021] A common example of equipping an axle suspension element with an actuator is to modify an existing damper accordingly. For instance, the length of such a damper can be adjustable via an electric spindle drive. In a shackle axle suspension, these dampers are oriented horizontally, so a change in the damper's length correlates with a pivoting movement of the axle around its vertical axis. Therefore, an actively controlled damper with a motor-driven length adjustment can deflect the axle from its centered position.

[0022] The actuator can be controlled in different ways, either individually or, to improve the reliability with which the chassis is adapted to the respective track and actively steered, possibly also in combination: Actual value sensors can detect the alignment of the work vehicle relative to the rail. This concerns the alignment of the work vehicle's longitudinal axis with respect to the straight or curved track section in front of the vehicle. A camera can be used as an example of sensor-based rail alignment detection, capturing the track's path in front of the work vehicle. Using image analysis software, it can detect not only deviations from a straight track but also whether the curve is to the right or left and how sharp it is. Instead of cameras, other sensors are commonly used, such as radar sensors. Both of the described sensor types operate without contact and are therefore wear-free.Alternatively, the alignment of the work vehicle relative to the track can be determined using guide rollers or similar mechanical elements. Based on the sensor data, the actuator can be controlled in such a way that the axle is deflected from its centered position to varying degrees, optimally adapted to the respective curve radius. The actuator can also be controlled using position data, since the track alignment is known. For example, using a distance counter or GPS data, the actuator can deflect the axle from its centered position to the extent necessary to align it optimally with the respective curve radius, as mentioned above.In a particularly simple technical embodiment, the actuator can be configured not to individually adjust the steering angle to the specific curve, but rather to move the axle from its centered position based on three different control signals: for example, a first, middle position for straight-ahead driving, a second position for right-hand turns, and a third position for left-hand turns. Alternatively, the actuator can assume only two different positions: a first position for straight-ahead driving and a second position for cornering. This latter scenario is suitable when, during cornering, only the actuator on the inner wheel or the actuator on the outer wheel is activated to deflect the axle from its centered position.In this case, too, the control system outputs three control signals; however, when negotiating curves, it only activates one of the two available actuators. With this particularly simple design, which avoids the need for the control system to send a multitude of different control signals to the actuator(s), the present proposal assumes that the curve position of the axle achievable by the actuator is better adapted to the actual track alignment than the various deflections that automatically occur in practice with a passively steered axle. The adverse effects, such as wheel rubbing on the rails, the resulting wear, and the associated noise emissions, are not completely eliminated in this way, but can be reduced to low levels that are not critical in practice.

[0023] The actuator or linkage, which is designed to actively deflect the axle, necessarily creates a connection between, on the one hand, a vehicle frame or a stationary element attached to it, referred to as the vehicle body, and, on the other hand, the axle or a movable element attached to it relative to the vehicle frame. In this respect, a rail-bound work vehicle differs from the other rail vehicles mentioned earlier, such as passenger vehicles: for example, passenger vehicles typically employ a two-stage suspension system for ride comfort. In this system, the wheels are sprung within a bogie, and the bogie itself is sprung relative to the vehicle frame or car body. This achieves the greatest possible decoupling of the wheels from the car body and the passenger seats within it.For the work vehicle, a loss of this decoupling to the greatest extent possible is not critical, and in any case, work vehicles are usually only single-stage sprung.

[0024] Various properties can be integrated into the actuators: Pulsed excitation, continuous excitation, actuator force limitation, damping integration, integrated displacement sensors

[0025] The actuators can be controlled in different ways: GPS sensor and / or stored database. Sensors that directly or indirectly record track condition: ∘ Mechanical sensor (roller) ∘ Non-contact sensor, e.g., camera with image recognition or radar. Manually at the driver's request.

[0026] Various actuators can be used in the implementation. Electrically driven ∘ Electromotive via rack and pinion / spindle ∘ Linear drive Hydraulically driven ∘ Hydraulic cylinder ∘ Rotary drive Pneumatically driven ∘ Pneumatic cylinder ∘ Rotary drive

[0027] An exemplary embodiment of the work vehicle to be produced by the method according to the invention is explained in more detail below with reference to the purely schematic drawings. These show: Fig. 1 a perspective view of a rail-bound, two-axle work vehicle, Fig. 2 a perspective view of a section of the chassis of the work vehicle detached from the rest of the work vehicle Fig. 1 , where this section shows the area of ​​a chassis, and Fig. 3 a side view of this chassis in the installed state on the work vehicle.

[0028] In Fig. 1 Figure 1 shows a rail-bound, two-axle work vehicle, comprising a chassis or frame 2, a superstructure 3 on the frame 2, and two bogies 4 below the frame 2. The superstructure 3 includes a driver's cab 5 on one side and a crane 6 on the other. The work vehicle 1 stands on a track 7, with one wheel 8 of each bogie 4 resting on a rail 9 of the track 7.

[0029] Fig. 2 The chassis 4 is shown. It has a wheelset gearbox 11 between the running wheels 8, which serves to drive an axle 12 of the chassis 4. The actual axle body is not directly visible in the drawing, but is indicated at 12. The two ends of the axle 12 are guided by a rocker arm 14, which has a cross member 15. The cross member 15 runs parallel to the axle 12 and carries a rocker arm 16 at each of its two ends, which extends in the direction of the axle 12.

[0030] In front of the wheelset gearbox 11, a bearing 17 is visible, below which and parallel to it runs a second, identical bearing. From this lower bearing, a tension-compression rod 18 extends forward, where it connects centrally to the frame 2 or the superstructure 3, i.e., to the unsprung part of the work vehicle 1, for example via a console not shown in the drawing.

[0031] The upper one, from Fig. 2 The visible bearing 17 serves to support an upright torque support 19, with the tension-compression rod 18 and this upright torque support 19 serving to support the rocker arm 14. The upright torque support 19 also extends centrally under the unsprung part of the work vehicle 1. Therefore, the rocker arm 14 is supported centrally on this unsprung part of the work vehicle 1 via both the tension-compression rod 18 and the torque support 19, thus enabling small oscillation movements of the chassis 4, which ultimately allow the wheels 8 to run sinusoidally on the rails 9.

[0032] The upright torque support 19 forms an opening 20 through which a horizontally oriented torque support 21 extends, which is articulated on one side to the wheelset gearbox 11 and on the other side is supported centrally on the unsprung part of the work vehicle 1.

[0033] All chassis components that are in Fig. 2 The components shown are therefore supported exclusively near the central axis of the work vehicle 1 on its frame 2 or on its superstructure 3.

[0034] In the illustrated embodiment, the upright torque support 19 of the rocker arm 14 has a component that is designed as a single piece and frames the opening 20. Alternatively, the upright torque support 19 could have two separate struts that leave a gap between them, which serves as the opening 20 and allows the horizontal torque support 21 of the gearbox 11 to pass through this opening 20.

[0035] Furthermore, in a modification of the illustrated embodiment, the opening 20 could be realized in the horizontal torque support 21 of the gearbox 11, so that in such a case the upright torque support 19 would not have to have the illustrated opening 20, but rather would itself be guided through the opening of the horizontal torque support 21.

[0036] Furthermore, the design of the in Fig. 2 The chassis 4 shown is essentially a known design, so that it need not be discussed in detail. By way of example only, reference is made to the brake discs 22 arranged between the running wheels 8 and the wheelset gearbox 11, as well as to a shackle suspension 23 of the running wheels 8 and to wheelset bearings 24 at the ends of the axle 12.

[0037] The torque supports 19 and 21 and the tension-compression rod 18 are connected to the frame 2 and the superstructure 3, respectively, via connection plates 25. Preferably, the connection is not made to the superstructure 3 of the work vehicle 1, but rather to its frame 2. This allows for the creation of very different work vehicles 1 using identical or similar frames 2 and different superstructures 3.

[0038] The shackle suspensions 23 allow the running wheels 8, and consequently the entire chassis 4, to move in such a way that it can follow the curve of the rails 9. In doing so, the chassis 4 performs a steering movement, deflecting it from its centered position by a certain steering angle around its vertical axis. These movements of the chassis 4 are damped by horizontally arranged shock absorbers 26, thus preventing uncontrolled fluttering movements.

[0039] Especially from Fig. 3 It is evident that a change in length of a shock absorber 26 displaces the associated wheel 8 longitudinally of the work vehicle 1 and thus causes a steering movement of the axle 12, unless the opposite shock absorber 26 simultaneously undergoes the same change in length in the same direction. The shock absorber 26 acts indirectly with one end on a swing arm 16, so that a change in length of the shock absorber 26 moves the swing arm 14 in a steering motion.

[0040] The chassis 4 can also move in an upright direction by means of a single-stage suspension in the form of coil springs 27. These movements of the axle 12 are also damped: for this purpose, upright shock absorbers are provided, which, to distinguish them from the horizontally arranged shock absorbers 26, are referred to as vertical dampers 28. A load cell 29 is provided as part of a load-dependent brake of the work vehicle 1. The load cell 29 detects the vehicle's load status and adjusts the respective brake pressure.

[0041] In the illustrated embodiment, the shock absorbers 26 on both sides of the chassis 4 are not merely designed as passive elements that are compressed to a shorter effective length or extended to a longer effective length due to external forces. Rather, each shock absorber 26 has an actuator located in its housing, which, as an active component, can effect a predetermined change in the length of the shock absorber 26. Accordingly, by changing the length of a single shock absorber 26, or by changing the length of both shock absorbers 26 in opposite directions, the chassis 4 can be adjusted to a predetermined steering angle. In the illustrated embodiment, the actuators are controlled by a wired connection via a control unit located in the driver's cab 5.

[0042] The shock absorber 26 is supported "in a fixed position", namely in relation to the frame 2, with its in Fig. 3 right end. This stationary end is fixed to a frame bracket 30, which in turn is attached to a so-called sword, which is fixed to a longitudinal member of the frame 2 projecting downwards, for example by welding or bolting. With its opposite "movable" end, in Fig. 3 On the left, the shock absorber 26 is mounted in an axle bracket 31. The actuator allows the shock absorber 26 to be extended or retracted. This movement is transmitted via the axle bracket 31 to an axle bearing housing 32, in which the axle 12 is mounted. As a result, the shock absorber 26 can move one end of the axle 12 forward or backward, thus pivoting the axle 12 about its vertical axis and performing a steering movement.

[0043] In contrast to the illustrated embodiment, an actuator can also be arranged outside a shock absorber 26. In particular, in contrast to the illustrated embodiment, an actuator can also be arranged away from a shock absorber 26 and act on other components, for example – and in each case at a distance from the central axis of the work vehicle 1 – directly on the swing arm 16 or the crossmember 15 of the swing arm 14, or directly on the axle 12. In the illustrated embodiment, the actuator, by virtue of its integration into a shock absorber 26, acts on the chassis 4 as far away as possible from the central axis of the work vehicle 1, which enables the deflection of the chassis 4 with the lowest possible steering forces and thus the lowest possible material stress on the components involved in the steering movement. Reference symbol:

[0044] 1 Work vehicle 2 Frame 3 Body 4 Chassis 5 Driver's cab 6 Crane 7 Track 8 Wheel 9 Rail 10 Chassis 11 Wheelset gearbox 12 Axle 14 Swing arm 15 Crossbeam 16 Swing arm 17 Bearing 18 Tension-compression rod 19 Upright torque arm 20 Opening 21 Horizontal torque arm 22 Brake disc 23 Swing arm suspension 24 Wheelset bearing 25 Mounting plate 26 Shock absorber 27 Coil spring 28 Vertical damper 29 Load cell 30 Frame bracket 31 Axle bracket 32 ​​Axle bearing housing

Claims

1. Method for manufacturing a rail-bound, two-axle work vehicle (1), wherein a rail-bound, two-axle work vehicle (1) • having a frame (2) and a body (3), • and having a chassis (4), which has two running wheels (8) which can rotate about a common rotation axis, wherein the chassis (4) is mounted pivotably about a vertical axis in such a way that the chassis (4) together with the running wheels (8) can be pivoted about the vertical axis at a steering angle following the course of the rails (9) when the work vehicle (1) is cornering, is provided, • and, on the basis of this specified design of the axle suspension, a component of this axle suspension that is provided in any case is additionally provided with an actuator, • wherein the actuator is operatively connected to the chassis (4) in such a way that the chassis (4) can be pivoted about its vertical axis to different positions by different movements of the actuator, • wherein the actuator is arranged on or in a shock absorber (26) of the axle suspension in such a way that the length of the shock absorber (26) can be adjusted by way of the actuator, and the work vehicle (1) is provided with a controller which actuates the actuator and is connected to the actuator in a signal-transmitting manner in such a way that, on the basis of control signals of the controller which are transmitted to the actuator, a movement of the actuator and thus the steering position of the chassis (4) can be controlled.

2. Method according to Claim 1, characterized in that the axle suspension is configured as a link suspension (23), wherein the shock absorber (26) is oriented horizontally and in the longitudinal direction of the work vehicle (1).

3. Method according to Claim 1 or 2, characterized in that the controller has a sensor which detects the orientation of the work vehicle (1) with respect to the track (7) or to a rail (9), wherein the controller is configured in such a way that it sends control signals to the actuator based on the received sensor data, the control signals causing movement of the actuator.

4. Method according to Claim 1 or 2, characterized in that the controller is connected to a receiver for position data, and in that the course of the track (7) is stored in a data memory, wherein the controller is configured in such a way that it sends control signals to the actuator based on the received position data, the control signals causing movement of the actuator.

5. Method according to Claim 1 or 2, characterized in that the controller is configured in such a way that it, while avoiding a large number of different control signals which are assigned to different bend radii, only sends a control signal for a right turn or a control signal for a left turn to an actuator, and a reset signal for straight-ahead travel.

6. Method according to Claim 1 or 2, characterized in that the frame (2) or body (3) of the work vehicle (1) is supported against the chassis (4) by a single-stage suspension.

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