TRACKBOUND VEHICLE WITH STEERING OF WHEEL AXLES

Abstract: A trackbound vehicle comprising a first and a second car (1), the longitudinal axes of which (17, 18) form an angle ( alpha ), interconnected at a joint (4) and being rotable in relation to each other around an axis of rotation (6), which passes through the joint, a number of bogies (5), each of which having a bogie frame (7), at least one wheel axle (10) attached to the bogie frame and at least two wheels (8, 9) with each wheel rigidly connected to a wheel axle, whereby a first bogie is arranged rotatable around said axis of rotation, which is centred between the wheels. The vehicle further comprises a first measuring device (21) for measuring the angle ( alpha ) between the longitudinal axes of the first and second car, an actuator (20) for aligning the first bogie in relation to the cars, and a calculating member (22) which, on the basis of the measured angle, produces a signal to the actuator for aligning the wheel axles in parallel with the bisectrix (19) to the angle between the longitudinal axes of the cars.

Description: Trackbound vehicle with steering of wheel axles TECHNICAL FIELD A trackbound vehicle comprising a first and a second car, the longitudinal axes of which form an angle, interconnected at a joint and rotatable in relation to each other around an axis of rotation, which passes through the joint, a number of bogies, each of which has a bogie frame, at least one wheel axle attached to the bogie frame and at least two wheels with each wheel rigidly connected to a wheel axle, wherein a first bogie is arranged rotatable around the mentioned axis of rotation, which is centred between the wheels . BACKGROUND ART The conventional technique for providing long trackbound vehicles with wheel arrangements is based on utilization of bogies, that is, rotatable, load-carrying structures comprising two or more wheelsets, wheel axles and suspension. To support a car body, at least two bogies are needed. The concept car body in this context is defined as the device which is intended to contain and/or constitute the base for the payload. A large number of solutions for steering such bogies through track curves, and devices for minimizing oscillating movements during travel, have been described over the years and today constitute examples of well-tested technique. The fact that bogies are used is also explained by the fact that the frame in the bogie permits two suspension steps between the track and the car body as well as improved possibilities of suspension of the brake and traction equipment. The general ambition is to make the vehicles simpler and lighter, partly in view of the purchasing and maintenance costs, partly in view of energy consumption when starting and stopping the vehicles. This also leads to the desire to reduce the weight of the bogies . One way of achieving vehicles with lower weight is to change to using single-axle bogies. One way of reducing the weight of the vehicle is to reduce the number of bogies. However, it is not possible to exceed a maximum permissible load per axle. For a given length of a train, the number of bogies and hence also the weight of the vehicle are reduced by placing two-wheeled bogies between the car bodies . Bogies placed in the manner described are known as Jacobs bogies . When Jacobs bogies are used, structures are often used which are interconnected at joints which may be in common with the joints in which the bogies are rotatable. The car bodies are placed spring- mounted on the structures . The wheel axle in a single-axle frame must be given a possibility of steering through track curves, while at the same time it is desired to counteract tendencies to oscillation and hunting movement of the bogie when driving at higher speeds . In track curves, the wheel axles in a trackbound vehicle should be set radially or almost radially to the track curve if negotiation of the curve is to be performed without friction and without major wear of wheel and rails. Steering a wheel axle through a track curve entails adjusting the wheel axle radially to the track curve, but may as well be expressed such that the wheels are adjusted and roll in the direction of tangent of the rails and almost tangentially to the direction of tangent of the rails. In train technology it has long been desirable to steer the wheel axles of a railway vehicle to align radially to the track both in track curves and along a straight track. The reason for this is that the running characteristics of such a vehicle may be considerably improved if steering is carried out. It is especially important to be able to steer the wheel axles if the speed of the vehicle is high, which is the case when using high-speed trains. When a railway vehicle is run along a track, the necessary conicity on the running surfaces of the wheels causes wheel undercarriages with non-steered wheel axles when running along straight tracks to describe a sinuous or wave-like movement. When negotiating curves, incorrectly aligned wheel axles cause the angle of application of the wheels with the rails to become greater than desirable. These conditions lead to drawbacks such as increased wear on the wheels of the vehicle and the rail because of unnecessarily great lateral forces between wheels and rail. The rail may get into contact with the wheel flanges and a risk of derailment may arise. The train comfort is also reduced when the roll properties deteriorate. The disturbances also give rise to disturbing noise from wheels and rail . The wear on wheels and rail is caused, inter alia, by the creep which arises due to the lateral forces, which create frictional movements between the wheels and the rail when the wheel axle in incorrectly aligned in relation to the track. Various ways of solving the problems described above have been presented over the years. The existing solutions are based on various principles which may primarily be divided into systems with passive steering and systems with active steering, respectively. Passive steering is obtained, for example, in those cases where the running surfaces of the wheels are conically shaped, whereby a wheel axle with such wheels strive to assume a position along the radius of the track. This is also usually called self-steering and occurs both in single-axle bogies and in multi-axle bogies in a number of different variants. As an example of self-steering in a single-axle bogie, reference is made to the patent document WO 94/07728. One problem which may be difficult to solve in case of self-steering is to obtain a damping of the self-steering which is adapted to the movement of the vehicle along both straight tracks and curves. The technique which is most closely related to the present invention is the principle for active steering of wheels in a railway vehicle which is described in the publication "The tilting talgo", Elektrische Bahnen, 5/1985, pp 156-162, 6/1985, pp 82-85. The technique which is described in that publication is based on the provision of linkage arms connected between a two-wheeled Jacobs bogie and the car bodies both behind and in front of the bogie, on both sides thereof. In curve track the linkage arms between the car bodies and the bogie will ensure that it is aligned with the wheel axles substantially perpendicular to the track. The disadvantage of the above-described technique is that rolling motion of a car body, as a result of, for example, oblique loading, will provide a steering deflection of the bogie. During assembly of the vehicle it has to be ensured that the bogie is perpendicular to the track in case of a straight track. From the points of view of service, cost and reliability, it may also be a disadvantage to use completely mechanical steering systems. OBJECT AND ADVANTAGES OF THE INVENTION The object of the invention is to suggest a railway vehicle in which the wheel axles are aligned radially to the track in a simple and reliable way. What characterizes a device according to the invention is clear from the invention. According to the invention, the bogie is controlled by means of actuators such that the wheel axles are aligned in parallel with the bisectrix to the longitudinal axes of the cars. The wheel axles are thus also aligned perpendicular to the track. By using an actuator for aligning the bogie, the mechanical construction may be made considerably less expensive compared with current constructions, while at the same time the angular adjustment is not influenced by oblique loading of the car body. Nor does the construction require the same precision during the assembly as a completely mechanical solution. By having the axis of rotation for the bogie frame centred in relation to the wheels and the wheel axle, the lateral movement of the car bodies is minimized when negotiating curves. By using measuring devices for measuring the angle of rotation between the bogie and the car, it is, furthermore, possible to provide a feedback to the steering of the bogie such that it is aligned with the axles perpendicular to the track. One aspect of the invention is to align the bogies at the ends of the trackbound vehicle at the same angle in relation to the car as the nearest bogie in relation to the same car. The wheel axles in the bogies at the ends of the trackbound vehicle will then be aligned perpendicular to the track. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a railway vehicle comprising two cars with a two-wheeled bogie at the joint between the cars. Figure 2 shows a railway vehicle comprising two cars with a two-wheeled bogie between the cars. Figure 3 shows a railway vehicle comprising two cars with a four-wheeled bogie between the cars . DESCRIPTION OF THE PREFERRED EMBODIMENTS A number of embodiments of the invention will be described with reference to the drawing. Figure 1 shows a railway vehicle comprising a first and a second car, wherein each car 1 is composed of a frame structure 2 from which a car body 3 is suspended. Suspension may be arranged between the car body and the frame . The cars with their frames are interconnected at the joint 4 and rotatable in relation to each other around the joint. Figure 2 shows a preferred embodiment of the invention in which a two-wheeled bogie 5 is suspended between the cars rotatable around an axis of rotation 6. The bogie has a bogie frame 7 and two wheels, 8 and 9, with the wheels arranged on a common wheel axle 10. The wheel axle is suspended from the bogie frame. The axis of rotation 6 is centred between the wheels and passes through the joint 4 of the cars. At the end of the first car, a second bogie 11 is suspended from the frame of the car. The bogie has a bogie frame 12 and two wheels, 13 and 14, suspended from a common second wheel axle 15. The bogie is rotatable around a second axis of rotation 16 centred between the wheels. In track curves, the longitudinal axes 17, 18 of the first and second cars will have a certain angle α between them. This angle determines how much the bogie, suspended between the cars, must be rotated for the wheel axle to be aligned in parallel with the bisectrix 19 to the angle α between the longitudinal axes of the cars. The steering of the bogie is ensured by the actuator 20. A measuring device 21 is used for measuring the angle between the longitudinal axes 17, 18 of the cars. The signal from the measuring device is processed in a calculating member 22 and used for controlling the deflection on the actuator 20 which is used for aligning the bogie in relation to the cars. The actuator is placed between the frame, for at least one of the cars coupled to the common axis of rotation, and the bogie. Alternatively, the wheels in the example above may be individually suspended from the bogie, with the wheels rigidly arranged on two parallel wheel axles . A vehicle in accordance with the invention may also comprise a second measuring device 23 which measures the angle between the bogie 5 and one of the cars. The second measuring device produces a signal, which is a measure of the angle through which the bogie has been rotated from the neutral position, to the calculating member 22. A signal from the second measuring device provides a feedback of the deflection of the actuator and may be used for ensuring that the rotation of the bogie is correct. In accordance with the invention, a second bogie 11 at the end of the first car may be aligned by using a second actuator 24, between the car and the second bogie 11, for rotating the second bogie through the same angle in relation to the first car as the angle through which the first bogie 5 is rotated in relation to the first car. A third measuring device 25 measures the angle between the first car and the second bogie 11. A signal from the third measuring device provides a feedback of the deflection of the actuator and may be used for ensuring that the rotation of the second bogie is correct. Alternatively, the wheels in the example above may be individually suspended from the bogie, with the wheels rigidly arranged on parallel axles. A vehicle according to the invention may comprise more than two cars . Figure 3 shows a vehicle in accordance with the invention, wherein the bogie 26 has four wheels with the wheels 27, 28, 29, 30 rigidly arranged, in pairs, on wheel axles 31, 32. The wheel axles are each suspended from the bogie rotatable around respective axes 33, 34. The bogie is suspended in so far as it is rotatable around an axis 35, centred between the wheels and the wheel axles, with the mentioned axis in common with an axis of rotation for the joint 6 of the cars. A measuring device 21 is used for measuring the angle between the longitudinal axes 17, 18 of two cars. The signal from the sensor is processed in a calculating member and is used for controlling the deflection on the actuator 20 which is used for aligning the bogie in relation to the cars . The actuator is placed between at least one of the cars, connected to the common axis of rotation, and the bogie. The bogie is adjusted such that a symmetry axis 36 between the two wheel axles coincides with the bisectrix 19 to the angle between the longitudinal axes of the cars. The signal from the sensor is used by the calculating member also for influencing the actuator 37, 38 acting between the bogie frame and the wheel axles . These actuators align the wheel axles perpendicular to the rail, both on the straight track and in a curve track. Alternatively, the wheels in the example above may be individually suspended from the bogie. A four-wheeled bogie according to the example may also be placed at the end of the vehicle. The wheel axles in the bogies are located in pairs on common lines. The fact that the axis of rotation is centred between the wheels in the four-wheeled bogie implies that the angle of rotation passes through the symmetry line for the wheel axles and at the same distance from the wheels.

Claims: CLAIMS 1. A trackbound vehicle comprising a first and a second car (1) , the longitudinal axes of which (17, 18) form an angle (α) , interconnected at an articulation point, or joint, (4) and being rotatable in relation to each other around an axis of rotation (6) , which passes through the joint, a number of bogies (5) , each of which having a bogie frame (7), at least one wheel axle (10) attached to the bogie frame and at least two wheels (8, 9) with each wheel rigidly connected to a wheel axle, whereby a first bogie is arranged rotatable around said axis of rotation, which is centred between the wheels, characterized in that it further comprises a first measuring device (21) for measuring the angle (α) between the longitudinal axes of the first and second car, an actuator (20) for aligning the first bogie in relation to the cars , and a calculating member (22) which, on the basis of the measured angle, produces a signal to the actuator for aligning the wheel axles in parallel with the bisectrix (19) to the angle between the longitudinal axes of the cars, a second bogie, at the end of the first car, which is controlled by the calculating member by means of at least one second actuator (24) acting between the first car and the second bogie, which second actuator rotates the second bogie through an equally large angle in relation to the first car as the angle through which the first bogie is rotated in relation to the first car. 2. A trackbound vehicle according to claim 1, characterized in that the vehicle also comprises a second measuring device (23), for measuring a second angle between the first bogie and one of the cars, and that the second measuring device produces a signal to the calculating member. 3. A trackbound vehicle according to claim 1 or 2 , characterized in that the wheels in the bogie are arranged on a common axle . 4. A trackbound vehicle according to claim 1, 2 or 3 , characterized in that the vehicle also comprises a third measuring device (25), for measuring the angle between the second bogie and the first car, and that the third measuring device produces a signal to the calculating member. 5. A trackbound vehicle according to any of the preceding claims, characterized in that the bogie has two wheels. 6. A trackbound vehicle according to claim 1, 2 or 4, characterized in that the bogies have four wheels . 7. A trackbound vehicle according to claim 1, 2 or 4, characterized in that bogies have four wheels, where the wheel axles, which may be rotated in relation to the bogie frame, are controlled by the calculating member by means of at least one third and one fourth actuator (37, 38), resulting in the wheel axles being aligned perpendicular to the track.

Inventors: LINDBLOM JULIUS, LINDBLOM, JULIUS
Applicants: ABB DAIMLER BENZ TRANSP, LINDBLOM JULIUS, ABB DAIMLER-BENZ TRANSPORTATION (TECHNOLOGY) GMBH, LINDBLOM, JULIUS
Application year: 1998
Main classification: B61F3
IPC codes: B61F3, B61F5