RAIL VEHICLE

Abstract: In a rail vehicle comprising a carriage body (1) supported by at least two bogies (5, 6), the carriage body comprises a body part (2), which at least in the lateral direction is displaceable in relation to the remainder of the carriage body. The rail vehicle also comprises a measuring means (16, 18, 20, 32) adapted to measure lateral motion of one of the bogies, a control means (14), which receives a signal, informing about lateral motions of one of the bogies, from the measuring means, and a drive means (4) for moving the body part in the lateral direction. The control means (14) is adapted to control the drive means to move the body part in response to the signal from the measuring means, thereby counteracting lateral oscillations in the carriage body.

Description: RAIL VEHICLE Field of the Invention The present invention relates to a rail vehicle and a method m connection with a rail vehicle. Background Art Rail vehicles are usually made up having a carriage body which is supported by two bogies with one or more axles and associated wheels. When driving such a rail vehicle along a track, vibrations and oscillations from the track are propagated through one or more bogies to the carriage body. If the vibrations conform with the natural frequency of the carriage body, an oscillation is induced m the carriage body. Traditionally, carriage bodies with a high natural frequency have been built by making them rigid and of a limited length so that the frequency of the vibrations has essentially been lower than the natural frequency of the carriage body. As the bogies roll along the track, they will m a well-known fashion move smusoidally owing to the conicity of the wheels. The frequency of the sinusoidal motion increases as the wheels on the axles are being worn, and besides increases as the speed of the rail vehicle increases. The deviations from the ideal track position that appear m railway tracks have the highest amplitude at low frequencies, and therefore vibrations originating from irregularities m the track will be most powerful at low frequencies . However the frequency of the vibrations will increase as the speed of the rail vehicle increases . There is an increasing demand for rail vehicles intended for high speeds. There is also a demand for longer carriages to obtain better space for passenger compartments. For improved performance characteristics there is also a demand for the carriages to have their own drive assembly and to be as light as possible to achieve good efficiency of the rail vehicle. Owing to these factors, the natural frequency of the carriage bodies increases while at the same time a higher speed causes the frequency of the vibrations to increase. There is thus an increased risk of lateral oscillations being induced m the carriage body. The oscillations are not desirable since they result m a lower degree of comfort and especially since they cause an increased risk of derailment . Swedish Patent 509,118 discloses a railway vehicle and a method for such a vehicle for reducing lateral oscillations m the carriage body of the railway vehicle by dynamically separating a partial mass from the total mass or bulk of the carriage body. As a result, the natural frequency of the bulk of the carriage body is increased, which causes elimination of the excitation of the carriage body oscillation. The partial mass is dynamically separated from the bulk of the carriage body with the aid of springs and damping means. However, it is necessary for the partial mass to be a relatively large part of the total mass of the carriage body for an optimal result. Moreover, the bulk of the carriage body must have a natural frequency which is higher than the frequencies that are excited by the sinusoidal motion of the bogies and irregularities m the track. This yields a restriction as to the reduction of the weight of the rail vehicle. Furthermore, the vibrations m the carriage body cannot be fully eliminated m a rail vehicle according to the above-mentioned Swedish patent. Japanese Patent Publication 06249284 discloses a method, according to which lateral vibrations of a carriage body are damped by moving a weight m relation to the carriage body m dependence on the measured lateral acceleration of the carriage body. A drawback of such a method is that oscillations with a measurable amplitude must have arisen before the signal from the measuring means becomes measurable . There is consequently a need for a rail vehicle and method for such a vehicle m which the above-mentioned drawbacks have been minimised. Summary of the Invention One object of the present invention is to provide a rail vehicle whose lateral oscillation is minimised. A further ob ect of the present invention is to provide a rail vehicle whose lateral oscillation, owing to the sinusoidal motion of its bogie, is minimised. One more object of the present invention is to provide a method for minimising lateral oscillations m a rail vehicle. An additional object of the present invention is to provide a method for minimising the effect of the bogies on the oscillations of the carriage body. These objects are achieved by means of a rail vehicle and a method for a rail vehicle according to the appended claims . The field of application of the invention is pre- ferably rail vehicles intended for high speeds, but the invention can be used for all types of rail vehicles. A rail vehicle according to the invention comprises a carriage body supported by at least two bogies, the carriage body comprising a body part, which at least m the lateral direction is displaceable m relation to the remainder of the carriage body. A rail vehicle according to the invention is characterised m that it also comprises a measuring means adapted to measure lateral motion of one of the bogies, a control means, which receives a signal, informing about the lateral motion of the bogie, from the measuring means, and a drive means for moving the body part m the lateral direction, the control means being adapted to control the drive means to move the body part m response to the signal from the measuring means, thereby counteracting lateral oscillations m the carriage body. By actively controlling, according to the invention, a laterally displaceable body part m response to a measured lateral motion of a bogie, it is possible to obtain essentially complete elimination of the excitation of carriage body vibrations while at the same time the mass of the body part need only be a small part of the total mass of the carriage body. It is also possible to reduce the weight of the vehicle since the rigidity requirements are lower m a vehicle according to the invention compar- ed with previously known vehicles owing to the fact that the natural frequency of the carriage body is allowed to be lower. The inventors have realised that the lateral oscillations m a carriage body are excited mainly by the sinusoidal motion of the bogies of the rail vehicle. In most cases the carriage body cannot be considered a rigid body and it is therefore difficult to filter out the relevant frequencies from measured oscillations of the carriage body. Consequently it will be extremely dif- ficult to damp the oscillation of the carriage body m the lateral direction by merely measuring the oscillation of the carriage body. By instead measuring, according to the invention, the motion of the bogies, it will be considerably easier to compensate for the oscillation applied by the bogies. The body part is advantageously displaced perpendicular to a longitudinal axis of the carriage body. The control means is advantageously provided with information about the dynamic properties of the rail vehicle, which has been obtained through experiments or theoretical calculations and which is used by the control means to control the body part motion performed by the drive means m such manner that oscillations m the carriage body are counteracted. For an optimal result, the control means must have detailed information about the dynamic properties of the rail vehicle. According to a particularly preferred embodiment of the invention, the lateral motion of at least one of the bogies and the lateral oscillation of the carriage body are measured with the aid of a first measuring means and a second measuring means, respectively. The control means uses the signals from both the first and the second measuring means to control the drive means to move the body part for the purpose of counteracting lateral oscillations of the carriage body. By the control means being fed forwards as well as backwards, lateral oscillations are efficiently counteracted while at the same time the demands for detailed information about the dynamic properties of the rail vehicle can be somewhat lower compared with the case if there is no feedback. The lateral oscillation of the carriage body is advantageously measured by means of an accelerometer which measures acceleration m the lateral direction. Alternatively, the longitudinal acceleration of the attachment of the transverse damping means to the car- riage body is measured. The bending of the carriage body can be determined by carrying out the measurement m at least two points which advantageously are located as far away as possible from the longitudinal symmetry axis of the carriage body. When feedback control and feedforward control are combined, it is advantageous if the control system first of all takes the feedforward control into consideration. It is particularly advantageous to measure the lateral motion of both bogies m the rail vehicle. By con- trolling the body part m response to the lateral motion of both bogies, oscillations m the carriage body are efficiently counteracted. Although the requirements as to the weight of the body part are lower m a vehicle according to the mven- tion, it is advantageous that the body part constitutes at least 1% of the mass of the rail vehicle m order to optimally counteract lateral oscillations of the carriage body. However, advantages of the invention are achieved also in the case where the body part constitutes less than 1% of the mass of the rail vehicle. The measurement of the lateral motion of the bogie can be carried out in a large number of ways. It is preferred to measure the transverse motion of the bogie by means of a gyro . The measurement of the lateral motion of the bogie can alternatively be carried out, for example, by measur- ing the force of the transverse damping means arranged between the bogie and the carriage body. The transverse damping means serve to damp the turning of the bogie in the lateral plane in relation to the carriage body. Alternatively, the measurement can be carried out by measuring by means of an accelerator the lateral acceleration of a point which is outside the centre of turning of the bogie. It goes without saying that the above features can be combined in the same embodiment . In order to further elucidate the invention, detailed embodiments will be described below, without, however, the invention being considered restricted thereto. Brief Description of the Drawing Fig. 1 is a schematic view of a rail vehicle accord- ing to a preferred embodiment of the present invention. Fig. 2 is a schematic block diagram of the function of a rail vehicle according to the present invention. Detailed Description of the Invention Fig. 1 is a schematic view of a rail vehicle com- prising a carriage body 1, a body part 2, which is suspended by means of springs 3 from the body 1. The body part 2 is displaceable in the lateral direction essentially perpendicular to the longitudinal axis of the carriage body with the aid of a drive means 4. The body part consists of e.g. a transformer. The carriage body is supported by bogies 5, 6 which are suspended from the carriage body and turnable about a centre of turning 7, 8 each. Each of the bogies has two axles 9, 10, 11, 12 and associated wheels 13. A control means 14 is also arranged on the rail vehicle and is connected to the drive means 4 via a control line 15. An accelerometer 16 is arranged m the centre of the rail vehicle for measuring lateral oscillations of the carriage body perpendicular to the longitudinal axis of the carriage body. The accelerometer is connected to the control unit 14 via a line 17. On one bogie 5 a gyro 18 is arranged, which is connected to the control unit 14 via a line 19. A transverse damping means 20 is arranged between a fixing point 21 on the carriage body and a fixing point 22 on the bogie. Fig. 2 is a schematic block diagram of the function of a rail vehicle according to the present invention. With reference to both Fig. 1 and Fig. 2, the control means 14 corresponds to the contents within the dashed frame 23. When the rail vehicle is driven on rails, the bogie 5 will move along a sine curve. The transverse motion will be detected by the gyro 18 and will be pass- ed on to the guide means 14 via the line 19. In Fig. 2, the sinusoidal motion is represented as a disturbance 14 affecting the bogie 5. The lateral oscillation of the rail vehicle is affected by the transverse motions 24 of the bogie m a process 26. The transverse motion of the bogie m the form of sinusoidal motion is measured by the gyro 18 and passed on to the control means m block 27. In block 27 there is information about the dynamic properties of the rail vehicle, i.e. information about the process 26, which consists of the connection between the lateral motion of the bogie and the lateral oscillations of the carriage body. In block 27, a reproduction of the process is made and passed on to block 28, where the signal from block 27 is added to the signal from block 31. The sum from block 28 affects the drive means which is represented by block 29, m response to the signal from block 27 and block 31. The force of the drive means is added to the force of the sinusoidal motion of the bogie, which is represented by block 25. Block 27 represents feedforward control . The lateral oscillation of the carriage body is measured by means of the accelerometer 16, which is represented by block 30. Block 30 is con- nected to a regulator 31 m the control means. The drive means 29 is actuated m response also to the signal from block 31. Blocks 30 and 31 represent feedback control m the system. In block 28, the signal from block 27 is considered most m order to obtain a quick reaction to the interference 24. The accelerometer 16 can be replaced by a measuring means which consists of at least two accelerometers 32 for measuring longitudinal acceleration, which are arranged adjacent to the fixing point 21 of the trans- verse damping means m the carriage body. The accelerometers 32 provide information about the bending of the carriage body. A person skilled m the art understands that the invention is not restricted to the embodiment described above and that many modifications are feasible within the scope of the invention. For example, the gyro 18 can be replaced by an accelerometer 34 arranged on the bogie. Alternatively, the gyro 18 can be replaced by a force- sensing device 33 m the transverse damping means 20, which measures the lateral motion of the bogie 5. In an alternative embodiment, there is only one of the accelerometers 16 and 18. This means that there is only a feedforward control or a feedback control m the block diagram m Fig. 2.

Claims: CLAIMS 1. A rail vehicle comprising a carriage body (1) supported by at least two bogies (5, 6) , the carriage body comprising a body part (2) , which at least m the lateral direction is displaceable relative to the remainder of the carriage body, c h a r a c t e r i s e d m that it also comprises a measuring means (16, 18, 20, 32) adapted to measure lateral motion of one of the bogies, a control means (14), which receives a signal, informing about the lateral motion of the bogie, from the measuring means, and a drive means (4) for moving the body part m the lateral direction, the control means (14) being adapted to control the drive means to move the body part m response to the signal from the measuring means, thereby counteracting lateral oscillations m the carriage body. 2. A rail vehicle as claimed m claim 1, c h a r a c t e r i s e d m that it comprises a first measuring means (18, 20) adapted to measure lateral motion of one of the bogies, a second measuring means (16, 32) adapted to measure lateral motion of the carriage body, a control means (14), which receives a first signal, informing about the lateral motion of the bogie, from the first measuring means and which receives a second signal, informing about the lateral motion of the carriage body, from the second measuring means, and a drive means (4) for moving the body part m the lateral direction, the control means being adapted to control the drive means to move the body part m response to the first and the second signal from the measuring means, thereby counteracting lateral oscillations of the carriage body. 3. A rail vehicle as claimed in claim 1 or 2, c h a r a c t e r i s e d in that the body part (2) constitutes at least 1% of the mass of the rail vehicle. 4. A rail vehicle as claimed in claim 2, c h a r - a c t e r i s e d in that it also comprises transverse damping means (20) arranged between the bogie and the carriage body, the measuring means for measuring the lateral motion of the carriage body being adapted to measure the force of the transverse damping means. 5. A rail vehicle as claimed in claim 2, c h a r a c t e r i s e d in that it also comprises transverse damping means (20) arranged between the bogie and the carriage body, the measuring means for measuring the lateral motion of the carriage body consisting of at least two, preferably four, transducers adapted to measure the longitudinal acceleration, thus measuring the bending pattern of the carriage body. 6. A rail vehicle as claimed in any one of claims 1-5, c h a r a c t e r i s e d in that the measuring means for measuring the lateral motion of the bogie consists of a gyro (18) arranged on the bogie. 7. A rail vehicle as claimed in any one of claims 1-5, c h a r a c t e r i s e d in that the measuring means for measuring the lateral motion of the bogie con- sists of an accelerometer (18) arranged on the bogie. 8. A method for reducing lateral vibrations in a rail vehicle comprising a carriage body (1) supported by at least two bogies (5, 6) and a body part (2) , which at least in the lateral direction is displaceable in rela- tion to the remainder of the carriage body, c h a r a c t e r i s e d by the steps of measuring lateral motion of one of the bogies, and moving the body part in the lateral direction in response to the measured lateral motion of the bogie. 9. A method as claimed in claim 8, c h a r a c t e r i s e d in that it also comprises the steps of measuring the lateral acceleration of the carriage body, and moving the body part in the lateral direction also in response to the lateral acceleration of the carriage body .

Inventors: PERSSON RICKARD, PERSSON, RICKARD
Applicants: DAIMLER CHRYSLER AG, PERSSON RICKARD, DAIMLERCHRYSLER AG, PERSSON, RICKARD
Application year: 2000
Main classification: B61F5
IPC codes: B61F5