Patent Application
20170166224
The invention relates to a chassis for a rail vehicle. The invention relates further to a rail vehicle together with a computer program.
In the case of chassis for rail vehicles there is a fundamental conflict of objectives between the dynamic running behavior when traveling round curves and the ride stability for straight-line travel at high speed. This conflict of objectives has already been known for a long time, and in the history of rail technology there have been the most varied approaches to solving it. Particularly in the most recent past, this conflict of objectives has gained renewed importance due to increasing stringency of the conditions for accessing the rail network by the infrastructure operators in Europe and in face of the constant discussion about the introduction of wear-dependent usage charges for the rail network.
From the disclosure document EP 1 193 154 A1, a method and a device are known for stabilizing the hunting oscillations of rail wheelsets. Provision is made that a turning moment is determined, from a metrologically detected acceleration of the wheelset horizontally at an angle to its direction of travel, which is imposed on the wheelset about its vertical axis. For this purpose an actuator, for example, is provided which, for example, can be a servo-hydraulic cylinder with an associated pressure provision (pump and supply storage).
The object underlying the invention can be seen as being to make available an improved chassis for a rail vehicle.
The object underlying the invention can also be seen as being to make available a corresponding method for operating a chassis for a rail vehicle.
The object underlying the invention can be seen as being to make available a corresponding rail vehicle.
The object underlying the invention can also be seen as being to specify a corresponding computer program.
These objects are achieved by means of the relevant subject of the independent claims. Advantageous embodiments of the invention are the subject in each case of dependent sub-claim.
From one point of view a chassis is made available, for a rail vehicle, comprising:
In accordance with a further aspect, a method is provided for operating the inventive chassis for a rail vehicle, comprising the following steps:
In accordance with yet another aspect, a rail vehicle is provided which comprises the inventive chassis.
In accordance with yet another aspect, a computer program is specified which comprises program code for carrying out the inventive method when the computer program is executed on a computer.
The invention thus encompasses in particular the idea of adjusting the longitudinal stiffness of a hydraulic bushing, of a bearing in an A-frame linkage, in that a particular hydraulic pressure is set in the hydraulic bushing, more precisely in the fluid chamber. By means of the active adjustment of the longitudinal stiffness it is thus advantageously possible to actively influence the hunting oscillations. These can be detected indirectly via a measurement of the wheelset accelerations. Since the adjustment is effected on the basis of, or dependent on, the wheelset accelerations, the hunting oscillations can be influenced in such a way that optimal track-following can be effected combined with minimal wear.
The hunting oscillations of the wheelset result from the vehicle alignment on the rails, and arise from the existing contact geometry between the wheel profile and the rail profile which, simplifying it, corresponds to a cone the outer surface of which rolls over a plane. The cone will then always roll on a circular path, determined by its angle. Here, to simplify, the wheelset corresponds to two cones arranged in opposition and rigidly joined together by an axle. In this case, as its two wheels roll along, rigidly joined together by the wheelset axle, the wheelset constantly wishes to make the advantageous attempt to adjust itself on a radial arc on the track (also on straight sections). Due to this radial setting, each of the two wheels rolls on different rolling radii on the track, so that what is known as a wheelset turning moment is generated which is in the opposite sense from its angular setting, which has as a consequence a radial setting in the opposite direction. The actual contact geometry between the wheel and rail is more complex, and has a non-linear behavior. The expression used here is so-called equivalent conicity. However, here again a hunting oscillation of the wheelset results from the difference in rolling radii, but this however no longer corresponds to a pure sine function. In order nevertheless to permit the desired radial setting of the wheelset it is aligned by the axle guide (A-frame) in such a way that a lateral displacement and an angular setting and turning movement about its vertical axis is possible. The hunting oscillation frequency is here dependent on the vehicle speed and the construction of the stiffness of the axle guide longitudinally and laterally relative to the vehicle's longitudinal axis. A soft axle guide is favorable to the turning movement, and hence to the radial setting capability of the wheelsets, that is the positive arc-following behavior on curved tracks with a relatively low travel speed, but during straight-line travel at high vehicle speed leads to unstable hunting oscillations.
In the case of a stiff axle guide, the wheelset has stable behavior on straight stretches, but its radial adjustment on track curves is made more difficult.
Together with the traction or braking forces, as applicable, from the drive and brake in the vehicle, the turning moments on the wheelset thus generated during the vehicle's travel on a track result in corresponding forces and accelerations which act longitudinally, laterally and as a turning moment about the vertical axis of the wheelset.
In accordance with the invention, therefore, this hunting oscillation is actively influenced in that the longitudinal stiffness of the hydraulic bushing is altered by means of an adjustment to the hydraulic pressure in the fluid chamber. In this way, an unfavorable hunting oscillation can be compensated, so that wear can be minimized and so that stable straight-line travel can be effected.
In accordance with one form of embodiment, provision is made that the adjustment device is designed to set a predetermined path over time for the hydraulic pressure, as a function of the measured wheelset acceleration, in order to impose on the wheelset a turning moment with a corresponding path over time.
In accordance with a further form of embodiment, provision is made that the adjustment device is designed, by adjusting the hydraulic pressure in the fluid chamber, to actively impose on the wheelset to which this fluid chamber corresponds a turning moment. By this means the technical advantage is achieved, in particular, that active steering is possible by adjustment of the hydraulic pressure. The turning moment can advantageously compensate for an unstable travel progress.
In another form of embodiment, provision is made that the bearing with the fluid chamber is the bearing on the wheelset side.
In accordance with a further form of embodiment, provision is made that the adjustment device has a pressure reservoir which can be connected to the fluid chamber. This produces the technical advantage, in particular, that a hydraulic pressure which is not at that moment required can be temporarily stored in the pressure reservoir, so that it can be reused at a later point in time in order then to adjust the hydraulic pressure in the fluid chamber. The pressure reservoir is constructed, in particular, to accept and reoutput the hydraulic fluid. That is to say that the pressure reservoir takes up and reoutputs, in particular, the hydraulic fluid. This is controlled, in particular, by means of the adjustment device. For example, a valve, for example an on-off valve, is provided between the fluid chamber and the pressure reservoir. In this way, the advantageous effect is achieved that the pressure reservoir can be connected up to and again disconnected from the fluid chamber.
In accordance with yet another form of embodiment, provision is made that the adjustment device has a pressure generation device which can be connected to the fluid chamber. This gives the technical advantage, in particular, that if additional hydraulic pressure is required in the fluid chamber this can be generated by means of the pressure generation device. Hence a particular pressure level can be ensured. In particular, this gives the technical advantage that it is possible to actively build up a pressure in the fluid chamber. This, in particular, against a flow of fluid which, in particular, is unavoidably produced due to the movement of the rail vehicle.
Because, due to the hunting oscillations, particular wheelset guidance forces arise which enforce hydraulic fluid flows. Thus the hydraulic fluid will respectively flow out of the fluid chamber or flow into it, depending on the wheelset guidance forces. This in- and out-flow can now be actively controlled or influenced. This is, in particular, an essential idea of the invention.
In accordance with a further form of embodiment, the frame-side bearings have elastomer bushings with a constant longitudinal and lateral stiffness, and the wheelset-side bearing have hydraulic bushings with a constant lateral stiffness, and variable longitudinal stiffness.
In accordance with one form of embodiment, the bearings of each A-frame linkage are arranged in each case at the corners of a horizontally aligned triangle with equal arm lengths, the apex of which forms the wheelset-side bearing and the base of which forms the frame-side bearing. By the symmetrically-distributed arrangement of the bearings relative to the longitudinal direction, at the corners of an isosceles triangle, one achieves a particularly high lateral stiffness of the A-frame linkage, which is determined for example by the properties of the elastomer in the bearings.
In another form of embodiment, provision is made that each hydraulic bushing has a fluid chamber which lies outside in the longitudinal direction and a fluid chamber which lies inside in the longitudinal direction, which are arranged to lie opposite each other in the longitudinal direction and can be filled with hydraulic fluid, wherein there is connected to each fluid chamber a fluid channel for the in- or out-flow respectively of hydraulic fluid respectively into or out of the fluid chamber, wherein the adjustment device is hydraulically coupled to the fluid channels and is constructed to adjust an in- or out-flow respectively of hydraulic fluid, so that it is possible to adjust the hydraulic pressure in the fluid chambers by means of outflows or inflows respectively of hydraulic fluid.
As already explained above, certain wheelset guidance forces arise from the hunting oscillations, which enforce hydraulic fluid flows. Provision is now made in accordance with the invention that these in- and out-flows are actively controlled and/or influenced. For example, valves which can be controlled are provided in the fluid channels. In particular, these valves can be opened and/or closed and/or controlled in such a way that a flow cross-section in the fluid channel is altered, that is for example enlarged or reduced. This advantageously allows an adjustment of a longitudinal stiffness to be adjusted in an advantageous manner. By this means, it is possible in an advantageous way to impose on the wheelset a particular turning moment. This can, for example, compensate a hunting oscillation in such a way that wear and/or noisy travel is minimized.
Lying inside and lying outside are here defined in relation to the longitudinal direction, which is defined as running parallel to the direction of travel or the rails. In the longitudinal direction, the first and second wheelsets are arranged one behind the other—expressed otherwise they are on the two sides of the center of a chassis—wherein a fluid chamber lying on the inner side faces towards the center of the chassis and a fluid chamber lying on the outer side faces away from the center of the chassis.
In accordance with a further form of embodiment, provision is made that hydraulic bushings which are arranged on the same side of the chassis are connected via external fluid channels in such a way that there is a hydraulic coupling from the fluid chambers lying on the outer side of the first wheelset to the fluid chambers lying on the inner side of the second wheelset and from the fluid chambers lying on the inner side of the first wheelset to the fluid chambers lying on the outer side of the second wheelset, wherein the adjustment device is hydraulically coupled to the external fluid channels.
In accordance with yet another form of embodiment, provision is made that each of the hydraulic bushings has in each case an internal fluid channel via which the fluid chamber which lies outside and the fluid chamber which lies inside on the same hydraulic bushing are hydraulically coupled, wherein the adjustment device comprises on/off valves, wherein an on/off valve is assigned to each internal fluid channel, by means of which the flow of hydraulic fluid through the fluid channel can be adjusted.
In the sense as intended by the present invention, inside means in particular that an internal fluid channel runs inside the hydraulic bushing. But inside, in the sense of the present invention, also means that such an internal fluid channel, while it may run outside the hydraulic bushing, does however exclusively link or hydraulically couple the fluid chamber which lies inside with the fluid chamber which lies outside on the same hydraulic bushing.
The forms of embodiment cited above in connection with the internal fluid channel and the external fluid channel can, in accordance with another form of embodiment, be provided as alternative forms of embodiment. That is to say, in particular, that there is a hydraulic decoupling between the fluid chambers of the same hydraulic bushing and an exclusively hydraulic coupling of the fluid chambers of several hydraulic bushings, as described in connection with the external fluid channels. As an alternative to this form of embodiment, there is a hydraulic decoupling of the fluid chambers of one hydraulic bushing from the fluid chambers of a further hydraulic bushing, and an exclusive coupling of the fluid chambers of the one and same hydraulic bushing, as described in connection with the internal fluid channels. In a further alternative form of embodiment, the individual fluid chambers of the hydraulic bushings are coupled with each other as above in connection with the external and internal fluid channels, wherein however in the fluid channels, that is in both the external and/or the internal fluid channels, valves are provided, for example on/off valves, in such a way as to effect the relevant coupling states by these valves being correspondingly respectively closed or opened. It is thereby advantageously possible, depending on the desired requirement, to switch in a particular coupling state (only the fluid chambers of the one and same hydraulic bus being hydraulically coupled, or the fluid chambers of several hydraulic bushings being coupled with each other, as explained above in connection with the external fluid channels).
In accordance with a further form of embodiment, provision is made that a pressure sensor is provided for measuring a hydraulic pressure in the fluid chamber. By this means, the technical advantage is achieved, in particular, that a pressure drop can be detected. It is then advantageously possible to initiate suitable measures, for example a warning.
In a preferred form of embodiment of the inventive chassis, each fluid chamber which is coupled via a fluid channel is assigned a pressure sensor, which reacts in the event that the pressure prevailing in the hydraulic fluid drops below a prescribable threshold value, wherein the pressure sensors are linked individually and/or serially with a pressure monitoring device, and wherein the pressure monitoring device is designed to transmit a warning signal to a central control device if an individual and/or all the pressure sensors is/are triggered. This makes possible a diagnosis in the event of a failure of the hydraulic system. The pressure sensors measure the pressure prevailing in the coupled fluid chambers, wherein a switch is closed as soon as the pressure drops below a threshold value. In the case when the pressure sensors are connected separately to the pressure monitoring device, it is there possible to determine separately for each hydraulic bushing whether there is a critical pressure drop. If the pressure sensors are connected in series to the pressure monitoring device, it is there possible to determine whether there is a critical pressure drop in the hydraulic bushings collectively. Depending on what is determined, a warning signal about the critical pressure drop can be output to a central control device of the rail vehicle. By this means the operational safety of the rail vehicle can be assured.
In another advantageous form of embodiment of the inventive chassis, there is a third wheelset arranged between the first wheelset and the second wheelset. The invention, which has up to here been described for a two-axle chassis, can also be applied for a three-axle chassis in which a further, third, inner wheelset, is arranged between the first and the second wheelset as outer wheelsets. In that the radial setting of the outer wheelsets is effected by A-frames in accordance with the invention, the third, inner, wheelset will in any case adopt a radial setting.
In accordance with one form of embodiment, a fluid channel is in the form of a rigid pipe or a flexible hose. In the case of several fluid channels, the fluid channels may, in particular, be the same or, for example, different in form.
In accordance with one form of embodiment, the rail vehicle is a locomotive, a traction unit, a streetcar, an underground vehicle or a suburban rail vehicle.
Forms of embodiment in connection with the chassis apply analogously for forms of embodiment in respect of the method, and vice versa. That is to say, the features and/or advantages as described in connection with the chassis apply analogously for the method, and vice versa.
The characteristics, features and advantages of this invention described above, together with the way and manner in which they are achieved, will become more clearly and more plainly comprehensible in conjunction with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawing, wherein
In what follows, it has been possible to use the same reference marks for the same features. Furthermore it has been determined that, for the sake of overall clarity, not all the reference marks for individual features will be shown in all the drawings.
A chassis 1 in accordance with the invention, on which a carriage body, not shown, of a rail vehicle, for example a locomotive, has a sprung support so that it can rotate about a vertical axis, has as shown in
As shown in
What is critical for the longitudinal stiffness c (on the assumption that no active influence is exercised on the fluid flows) of the hydraulic bushings 12 is here the frequency f at which lateral accelerations are evoked in the elastomer element 27 from outside by the hunting oscillations of the wheelsets 3 and 4. Apart from a high lateral stiffness, the hydraulic bushings 12 have a variable longitudinal stiffness c which is dependent on the excitation frequency, the nature of which is indicated in
In the form of embodiment as shown in
In the embodiments described above the assumption has been made that the fluid flows in or out of the fluid chambers, as applicable, solely because of the wheelset guidance forces. However, in accordance with the invention provision is made that active influence is exercised on the flow behavior of the hydraulic fluid. This will be explained in more detail in what follows.
Thus, drawn in
The acceleration signals 603 are fed to a regulatory device 605. This filters the acceleration signals 603, in particular in real time, as a function of the stiffness relationships of the A-frame linkages 8, of the hydraulic bushings 12 and the individual pipes of the hydraulic system, that is in particular the external channels 34, where these stiffness relationships are stored in the regulatory device 605 as benchmarks, so that the filtered acceleration signals can be used as the basis for regulation of the longitudinal stiffness. From the accelerations thus filtered and appropriate setpoint values, the regulatory device 605, which can for example be in the form of a PI regulator, forms a difference signal which supplies the regulating variable for a pressure generating device 607, which comprises a hydropulser, not shown, and a pressure generator, not shown. Together with a pressure generator, the hydropulser forms a hydraulic pressure signal, which is suitable for influencing highly dynamic hunting oscillations of the wheelsets 3 and 4 and to influence accordingly their setting on the track. For a suitable switching frequency (, which is determined) of the fluid chambers 31 and 32 one can thereby, when the vehicle's travel is unstable, advantageously stabilize the wheelsets 3 and 4 by means of the A-frame linkages 8 and hydraulic bushings 12 by imposing a frequency pattern which is counter-phase with the hunting oscillations. In particular, on sharp track curves one can then, by suitable hydraulic switching of the fluid chambers 31 and 32, effect active steering of the wheelsets 3 and 4 for the purpose of optimizing the track guidance and minimizing wear of the wheel running surfaces. The suitable switching frequency is determined, in particular, as a function of the measured wheelset accelerations.
That is to say, the pressure generation device 607 can set a hydraulic pressure in the fluid chambers 31 and 32 of the individual hydraulic bushings 12. This, in particular, as a function of the measured acceleration signals 603. For this purpose, the regulatory device 605 comprises a signal filter for the acceleration signals 603, in particular a real-time signal filter. In particular, the regulatory device 605 comprises a signal computer with a measured value converter, in particular a real-time signal computer with a measured value converter. The regulatory device 605 comprises in addition a difference calculator with a PI regulator and a setpoint value output for a pulse signal converter. Hence the regulatory device 605 comprises in particular a pulse signal converter with a valve control unit for controlling valves, in particular on/off valves. For the sake of clarity, these valves are not shown in
The pressure generation device 607 comprises in addition a hydraulic pulser, which works as an energy converter and generation unit for the required control pulse pattern and for the hydraulic pressure for the hydraulic bushings 12 in the A-frame linkages 8. In one form of embodiment, which is not shown, a separate pressure generator and/or a separate pressure reservoir are provided, to ensure the required hydraulic pressure level for an active stability regulation and steering of the wheelsets 3 and 4.
In one form of embodiment, which is not shown, pressure monitoring is provided, with one pressure sensor for each coupled fluid chamber 31, 32. By this means, a diagnosis is advantageously made possible in the event of a failure, a leakage.
So, in
The regulatory device 605 and the pressure generation device 607 form an adjustment device for setting a hydraulic pressure in the fluid chambers 31, 32.
Analogously to
In the forms of embodiment shown in
Analogously to
Thus the on/off valves 703 together with the regulatory device 605 form an adjustment facility for adjusting a hydraulic pressure in the fluid chambers 31, 32.
Hence, the inventive thinking lies in particular in a simple application of the previously proven concept of an A-frame linkage in the chassis and its equipping with hydraulic bushings together with their force-related regulation by the influencing and changing, for example imposition, of the hydraulic pressure level in their fluid chambers for the purpose of actively influencing the linkage characteristics of the axle linkages on the wheelsets of the chassis, and for the purpose of utilizing an active stability regulation by the imposition of a pulse pattern which is counter-phase with the hunting oscillation of the wheelset.
Provision is thus made to generate active control forces by the use of a hydraulic pulser. In addition, provision is made for the use of acceleration sensors, real-time signal filters, real-time signal computers together with measured value converters for the purpose of setpoint output for the regulatory device, with difference formers and pulse signal converters for the hydraulic controller and the actuators, in particular the on/off valves. Hence, in accordance with the invention provision is made for the use of hydraulically coupled wheelsets by appropriate hydraulic connection and actuation of the fluid chambers in the hydraulic bushings on the A-frame linkages to steer the wheelsets in the chassis. Advantageously, in accordance with one form of embodiment, provision is made for the application of pressure monitoring, by means of pressure sensors on the coupled fluid chambers, as a safety facility in the event of a failure of the hydraulic bushings and in the case of impermissible leakages in the hydraulic system of the active chassis control. In accordance with the invention, in accordance with one form of embodiment, the formation of an active turning moment damper is advantageously provided for stabilizing the wheelset running. The active chassis linkage and the stability regulation, together with the active turning moment damper, can be applied for single and multi-axle chassis, for undriven and driven chassis, for example bogies.
Although the details of the invention have been more closely illustrated and described by the preferred exemplary embodiments, the invention is not restricted by the examples disclosed and other variants can be derived from it by a specialist without going outside the scope of protection of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 214 055.2 | Jul 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/065069 | 7/2/2015 | WO | 00 |
