Method for a general detection of derailment

0001The invention relates to a method for detecting deregistered states of wheels of a rail vehicle by determining at least one characteristic for a derailment characteristic value, which is compared with at least one predetermined target value, wherein when exceeding a predetermined deviation of the characteristic value of the desired value, a reference signal and / or emergency braking is triggered.

0002Under derailed conditions, this document is understood to mean pre-critical conditions that are substantially immediately preceded by derailment of a wheel or wheelset and local derailment conditions, that is, conditions that correspond to derailment of one or more wheels / wheelsets of a rail vehicle.

0003Before there is a complete derailment of a rail vehicle or a rail vehicle association comes, usually the above-mentioned, local or pre-critical derailment conditions characterized by changes in wheel-rail contact. Local derailment conditions, which are indeed the cause of a complete derailment of the rail vehicle, but not a complete derailment of the rail vehicle or Rail vehicle association correspond, for example, from the lane jumping a wheel or Wheel set of the rail vehicle so that some wheels no longer run on tracks. At a later time, it may then, for example when crossing a switch, come to a complete derailment. A pre-critical derailment condition can, for example, represent a run-up of the wheel flange of a wheel on the tracks, so that a correct wheel-rail contact is no longer guaranteed.

0004In this context, for example, EP 0 697 320 A1 has become known. In the solution proposed there, at least one sensor is arranged in the region of a wheelset axle, with which the position of the wheels and the axle with respect to the rails can be determined and at a deviation of this position via a predetermined tolerance value of the sensor emits a signal transmitted by transmission means to a central Job is transferable. A particular disadvantage of the proposed solution is that only one parameter is used to determine a derailed state, namely the relative position from axis to rail plane, since it can also lead to derailments in which the relative position of the axes to the rail plane is not significantly different a not derailed state distinguishes.

0005EP 0 734 925 discloses a derailment detector which is combined with an emergency brake valve in the form of an emergency brake block. The derailment detector is designed as a shock sensor and has a weight body, which is biased by a spring in the direction of the emergency brake valve. The reactivity of the derailment detector is determined by the mass of the weight body and its spring tension. A disadvantage of this sensor is that it can not distinguish between damage to the track and an actual derailment situation, which can lead to unwanted tripping of emergency braking.

0006US 3 994 459 describes a system for detecting derailment conditions of a rail vehicle. In the disclosed system, a radio transmitter is provided which has elements that respond to vertical accelerations resulting from derailed conditions. In the event that a derailed condition is detected, a radio signal is transmitted to a receiver located in a checkpoint, which has an alarm output unit to indicate a derailed condition. A disadvantage of this solution is that no pre-critical derailment conditions can be detected.

0007US 5 433 111 A describes an apparatus and a method for detecting wheel damage of a rail vehicle. The known device has a measuring unit for determining the axis rotation of a wheelset and a motion sensor, for example an acceleration sensor, for detecting movements vertically to the rail plane. If a wheel damage occurs, an acceleration signal in the vertical direction is generated with the period of the axis rotation, which allows a conclusion as to whether a wheel damage is present. From the technical teaching this document does not follow that as can be concluded from the signals generated on a derailed condition of the rail vehicle.

0008DE 199 19 604 A1 describes a method or a device for detecting errors occurring in wheels of rail vehicles. For this purpose, the signal profiles of acceleration signals generated on the rail vehicle are considered in the time domain, wherein based on the waveform a damaged wheel condition is to be detected. To detect a derailed condition, however, other, additional measurements are required in addition to the detection of accelerations. A disadvantage of this invention is especially the large metrological effort, which is also associated with high costs.

0009DE 298 11 354 U1 describes a device for monitoring wheels, in which an acoustoelectric sensor is provided on a vehicle axle or on a wheel shaft or wheel which converts acoustic signals into electrical signals.

0010DE 298 11 208 U1 discloses a wheel monitoring system for multi-axle vehicles, wherein at each wheel axle sensors are arranged which detect vibrations caused by bumps on the Abrollweg arranged on the axles wheels. Furthermore, an evaluation unit is provided, which is set up to check whether all the sensors, which are arranged on successive axes, in each case transmit signals corresponding to one another when passing over the unevennesses. The evaluation unit detects if not all sensors give the same signal and triggers an alarm in this case or the vehicle is automatically stopped.

0011A disadvantage of the known device is that no quantitative and qualitative detection of derailment conditions or pre-critical derailment conditions is possible.

0012JP 09039790 describes a method for detecting a derailed condition in a rail vehicle based on a characteristic value, wherein the vertical acceleration is measured at a position of the bogie frame on a suspension. The value determined by integrating the measured acceleration twice is set to -80 mm, whereby an alarm signal is generated when a determined characteristic value is below this setpoint value. A disadvantage of JP 09039790 is, inter alia, that in a faulty or defective suspension erroneously a derailed condition can be detected.

0013JP 10278795 A discloses a derailment detector having a capacitive acceleration sensor which is arranged on a rail vehicle and receives accelerations in the vertical direction. The output of a counter, which converts changes in the acceleration signal into frequency changes, is connected to a microcomputer, which can determine whether a deregistered condition exists. This derailment detector also has the disadvantage that with it no quantitative and qualitative analysis of a derailed state or a pre-critical derailment condition possible.

0014In summary, it can be said that with the known devices for derailment detection only a certain type of derailment condition can be detected and the susceptibility to error is very high.

0015It is therefore an object of the invention to provide a way which makes it possible to detect a derailment condition with great certainty and to prevent a momentous accident.

0016This object is achieved by a method of the type mentioned in the present invention that, at least one acceleration signal is generated in the region of an axle bearing of at least one wheel, and / or continuously determines the respective longitudinal acceleration at at least two points of a bogie frame and detects it as a longitudinal acceleration signal and / or generates a rotational frequency signal on at least one wheel axle, where from the at least one, acceleration signal generated in the region of an axis bearing and / or the longitudinal acceleration signals and / or from the at least one rotational frequency signal of the at least one, for a derailment characteristic characteristic value is determined.

0017This solution allows a comprehensive analysis of the forces acting on the bogie of a rail vehicle accelerations, the course of which can be deduced with great certainty on a derailment condition of individual wheels or wheelsets and entire bogies.

0018Conveniently, to calculate the characteristic value, signal values ​​of the at least one acceleration signal generated in the region of an axle bearing, which lie within a predefinable time window, are subjected to a Fourier transformation or another unitary transformation which maps the time range of a signal onto the frequency range.

0019To calculate a first parameter characteristic for a derailment condition, the diameter of the wheel of the rail vehicle is determined on the basis of the at least one acceleration signal and the at least one rotational frequency signal, wherein the first characteristic characteristic value for a derailed condition is calculated on the basis of changes in the wheel diameter.

0020In each case, at least one acceleration signal is generated on at least two axle bearings one behind the other in the direction of travel and at least one rotational frequency signal is generated on the axles of the wheels mounted in these axle bearings.

0021Subsequently, to calculate the diameter of the wheel, a characteristic of the traveled route threshold frequency oscillation or threshold frequency is determined.

0022The calculation of the first characteristic value can be simplified in that signal values ​​that lie within a predefinable time interval are subjected to a Fourier transformation and from the Fourier transform of the signal values ​​the threshold frequency oscillation characteristic of a traveled distance or Threshold frequency is determined, which is associated with at least one front and / or rear wheel with respect to the direction of travel. As a result, the phase angle of the threshold frequency oscillation can be determined and the phase difference of the threshold frequency oscillation associated with a front and a rear wheel can be formed. The threshold distance can then be calculated from the phase difference of the threshold compartment oscillation, and the vehicle speed can be determined from the threshold distance and the threshold compartment frequency. The diameter of the wheel can then be calculated from the rotational frequency of the axle and the travel speed of the rail vehicle.

0023In order to form a second characteristic value for characterizing a derailed state, a predeterminable number of radial wheel harmonics can be determined from the at least one acceleration signal recorded in the region of an axis bearing, possibly from the transformations of the signal values. In the context of the calculation of the second characteristic value, an average value may further be formed from amplitudes of a predeterminable number of radial health harmonics.

0024Advantageously, the phase angles of the radial health harmonics are determined, wherein the course of the phase angles is used for characteristic value formation.

0025Another possibility for determining the second characteristic value is to carry out a cepstral analysis of the at least one further acceleration signal.

0026An advantageous variant of the invention for forming a third characteristic value is that the frequency ranges lying in the vicinity of the resonance frequencies of the wheel are compared continuously with a spectrum recorded at another time.

0027The method according to the invention can be further improved by determining the angular acceleration and / or the angular velocity of the wheel axle on the basis of the rotational frequency, and using the speed or acceleration characteristics to determine a fourth characteristic characteristic value for a derailed state.

0028To form a fifth characteristic value, the cross-correlation function of two acceleration signals recorded in the region of the axle bearings, which are each assigned to a front and a rear wheel, can be calculated within a predefinable time window.

0029An easy-to-implement variant of the invention is to determine the fifth characteristic value on the basis of the position and / or the amplitude of the maximum of the cross-correlation function.

0030In a preferred variant of the invention, at least one longitudinal acceleration signal is generated at a predeterminable distance from and to both sides of the longitudinal center plane of the bogie. which reproduces the course of acceleration of the bogie in the longitudinal direction and further generates at least one lateral acceleration signal, showing the course of the acceleration of the bogie parallel to the rail plane and normal to the direction of travel of the rail vehicle, wherein a sixth characteristic value is formed from the acceleration signals.

0031To form the sixth characteristic from the acceleration signals, the tangential acceleration of the center of gravity of the bogie and the rotational acceleration about the center of gravity can be calculated. On the basis of the curves of the calculated tangential and rotational acceleration, the sixth characteristic value can be calculated thereon.

0032For the realization of the method according to the invention, in particular, a device is suitable for detecting out-of-service conditions of wheels of a rail vehicle with at least one bogie, wherein at least one acceleration sensor is provided on the rail vehicle, which is in communication with an evaluation unit, which is set up receive acceleration signals from the at least one acceleration sensor and to determine therefrom at least one characteristic value that is characteristic of a derailment state and to compare this characteristic value with at least one predefinable setpoint value, wherein the evaluation unit is further adapted to when a predefinable deviation of the characteristic value from the desired value is exceeded, generating a warning signal and / or initiating emergency braking, wherein at least one acceleration sensor is arranged in the region of an axle bearing of at least one wheel, and / or at least two points of the bogie each at least one longitudinal acceleration sensor is arranged, which is set up to measure the respective longitudinal acceleration and / or at least one rotational frequency sensor is arranged on at least one wheel axle of a wheel, which is in communication with the evaluation unit.

0033In a preferred embodiment, the evaluation unit is set up for calculating the characteristic value signal values ​​of the at least one acceleration signal generated in the region of an axle bearing, which lie within a predefinable time window, a Fourier transformation or another unitary transformation, which determines the time range of a signal on the frequency / Phase domain maps, subject.

0034It has been proven in practice that the evaluation unit is set up to determine the diameter of the wheel based on the at least one recorded in the region of an axle bearing acceleration signal and the rotational frequency signal, and on the basis of changes in the wheel diameter a first characteristic of a derailed characteristic value to calculate.

0035Advantageously, at least two axle bearings arranged one behind the other in the direction of travel each have at least one acceleration sensor, wherein at least one rotational frequency sensor is arranged on each axle of the wheels mounted in these axle bearings.

0036Furthermore, it is advantageous if the evaluation unit is set up to calculate the diameter of the wheel and / or the travel speed characteristic of the traveled route threshold frequency oscillation or Threshold frequency to determine and from the Fourier transform of the signal values ​​of the at least one further acceleration signal, the at least one with respect to the direction of travel front and / or rear wheel associated with threshold frequency oscillation or To determine threshold frequency.

0037Furthermore, the evaluation unit is set up to calculate the threshold distance from the phase difference of the threshold compartment oscillation and to determine the driving speed from the threshold distance and the threshold compartment frequency.

0038To determine the first characteristic value, the evaluation unit is set up to calculate the diameter of the wheel from the rotational frequency of the axle and the travel speed of the rail vehicle.

0039An advantageous variant of the invention provides that the evaluation unit is set up to determine from the at least one acceleration signal, where appropriate from the transform of the signal values ​​of the at least one acceleration signal, a predeterminable number of Radunrundheitsharmonischen and from this a second, for a derailed condition of a rail vehicle to calculate the characteristic characteristic value.

0040In an advantageous embodiment of the invention, the evaluation unit is set up to form an average value for the calculation of the second characteristic value from amplitudes of a predeterminable number of radial health harmonics.

0041A practice-proven embodiment of the invention provides that the evaluation unit is set up to perform a cepstral analysis of the at least one acceleration signal to determine the second characteristic value.

0042The reliability can be increased by the fact that the evaluation unit is set up to determine the angular acceleration and / or the angular velocity of the wheel axle based on the rotational frequency signal and to determine a fourth characteristic value for a derailed condition on the basis of the angular velocity or angular acceleration characteristics.

0043Further advantages can be achieved in that the evaluation unit is set up to form a fifth characteristic value and, within a predefinable time window, to calculate the cross-correlation function of two acceleration signals recorded in the region of the axle bearings, which are each assigned to a front and a rear wheel ,

0044An easy-to-implement variant of the invention consists in that the evaluation unit is set up to determine the fifth characteristic value on the basis of the position and / or the amplitude of the maximum of the cross-correlation function.

0045A favorable variant of the invention provides at least one longitudinal acceleration sensor is arranged on both sides of the longitudinal center plane of the bogie and at least one further acceleration sensor for determining the transverse acceleration is arranged on the bogie, wherein the evaluation unit is set up to receive longitudinal acceleration signals from the longitudinal acceleration sensors and at least one lateral acceleration signal from the further acceleration sensor and from the longitudinal acceleration signals, which represent the course of the longitudinal acceleration of the bogie and the acceleration signal, which shows the course of the lateral acceleration of the bogie, to form a sixth characteristic value.

0046For this purpose, the evaluation unit can be set up to calculate from the acceleration signals the tangential acceleration of the center of gravity of the bogie and the rotational acceleration about the center of gravity in order to calculate the sixth characteristic value based on the courses of these accelerations.

0047The invention together with further advantages is illustrated below with reference to some non-limiting embodiments which are illustrated in the drawing, in which show schematically:<dl id="dl0001"><dt>Fig. 1</dt><dd>a bogie of a rail vehicle in side view with an arrangement of acceleration sensors according to the invention for determining a derailed state in a side view,</dd><dt>Fig. 2</dt><dd>the bogie of Fig. 1 in plan view,</dd><dt>Fig. 3</dt><dd>a section of an amplitude spectrum of two acceleration signals, which come from two in the direction of travel successive axle bearings,</dd><dt>Fig. 4</dt><dd>a section of a phase spectrum of two acceleration signals, which come from two consecutively lying in the direction of axle bearings,</dd><dt>Fig. 5</dt><dd>a simplified block diagram of a first part of an evaluation unit of a device according to the invention,</dd><dt>Fig. 6</dt><dd>the course of the calculated diameter of a wheel correctly running on rails,</dd><dt>Fig. 7</dt><dd>the course of the calculated diameter of a derailed wheel,</dd><dt>Fig. 8</dt><dd>a simplified block diagram of a second part of an evaluation unit of a device according to the invention,</dd><dt>Fig. 9</dt><dd>a wheel set with a wheel flange of a wheel climbed on the rail head in frontal view,</dd><dt>Fig. 10</dt><dd>a derailed wheel running on a concrete bed in lateral view,</dd><dt>Fig. 11</dt><dd>a derailed wheel set with wheels running on a concrete bed in frontal view,</dd><dt>Fig. 12</dt><dd>a derailed wheel running on a threshold track in lateral view,</dd><dt>Fig. 13</dt><dd>a derailed wheel set with wheels running on a threshold track in frontal view,</dd><dt>Fig. 14</dt><dd>a section of an amplitude spectrum of an acceleration signal in which the acceleration is plotted on the ordinate and the frequencies on the abscissa,</dd><dt>Fig. 15</dt><dd>a further section of an amplitude spectrum of an acceleration signal,</dd><dt>Fig. 16</dt><dd>a cepstrum of the amplitude spectrum of FIG. 15,</dd><dt>Fig. 17</dt><dd>a section of a broadband amplitude spectrum of an acceleration signal with highlighted resonance points,</dd><dt>Fig. 18</dt><dd>a simplified block diagram of a third part of an evaluation unit of a device according to the invention,</dd><dt>Fig. 19</dt><dd>a general course of the rotational frequency of the axis of a wheelset traveling on rails during a journey, in which the ordinate represents the rotational frequency and the abscissa the time,</dd><dt>Fig. 20</dt><dd>a detail from FIG. 19 at a relatively constant travel speed, FIG.</dd><dt>Fig. 21</dt><dd>the range of the course of the rotational frequency for a derailed wheel set shown in FIG. 20,</dd><dt>Fig. 22</dt><dd>a simplified block diagram of a fourth part of an evaluation unit of a device according to the invention,</dd><dt>Fig. 23</dt><dd>a section of the cross-correlation function of two acceleration signals, which come from successive axle bearings, which are arranged on the same bogie side,</dd><dt>Fig. 24</dt><dd>a simplified block diagram of a fifth part of an evaluation unit of a device according to the invention,</dd><dt>Fig. 25</dt><dd>an acceleration distribution on a bogie,</dd><dt>Fig. 26</dt><dd>a simplified block diagram of a sixth part of an evaluation of a device according to the invention and</dd><dt>Fig. 27</dt><dd>a simplified block diagram of a device according to the invention.</dd></dl>

0048According to FIG. 1, two acceleration sensors BS1, BS2 with vertical direction of action are provided for a device according to the invention for determining a derailed state of a rail vehicle, which are each arranged one behind the other in the direction of travel FA1, FA2 of the bogie DRE of the rail vehicle in the area of ​​an axle bearing. The possible directions of travel FA1, FA2 of the rail vehicle are indicated by arrows.

0049When driving over thresholds SWE, due to the stiffness variation of the tracks - in the region of a threshold SWE, the rigidity is increased compared to a track section situated between two thresholds SWE - vibrations are induced in the bogie DRE. These oscillations can be measured in the form of characteristic acceleration fluctuations in the area of ​​the axle bearings AX1, AX2, AX3, AX4, with a selected vibration component, the so-called threshold vibration, conclusions about the threshold distance d_s or the speed of travel of the rail vehicle permits.

0050The threshold distance d_s between two thresholds SWE essentially corresponds to one period of the threshold frequency oscillation.

0051An essential element of the present invention is the recognition that particularly representative measurement results can be achieved if the direction of action of the acceleration sensors BS1, BS2 is substantially normal to the rail plane or parallel to the direction of travel of the rail vehicle. In the drawing, the direction of travel FA1, FA2 and the direction of action of the acceleration sensors BSE is shown with arrows.

0052In the direction of action of an acceleration sensor BSE, this document refers to the direction in which the sensor can absorb acceleration forces and deliver signals.

0053The acceleration sensors BS1, BS2 can be designed, for example, as piezoelectric sensors in which, in a known manner, a piezoelectric crystal is arranged between two capacitor plates running parallel to one another. If this type of sensor is used, as a result of the fact that the two capacitor plates run essentially parallel to the direction of travel of the rail vehicle, a direction of action WIR of the acceleration sensors BSE running normal to the direction of travel FA1, FA2 can be achieved. Of course, other known acceleration sensors based on other mechanisms may also be used.

0054From the threshold frequency can be at a known threshold distance d_s the relative speed of the wheel RA1, RA2, RA3, RA4 along the rail or the travel speed of the rail vehicle are determined according to the following formula:<maths id="math0001" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">V = ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> * D</mtext></mrow><mrow><mtext mathvariant="italic">S</mtext></mrow></msub><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0001.tif" /></maths> where V is the travel speed of the rail vehicle and <i>ν</i>_<i>SF</i> denote the threshold frequency.

0055The position of the threshold frequency in the frequency spectrum is both directly and indirectly in the just-mentioned formula for determining the vehicle speed V on the determination of the threshold distance d_s and must therefore be determined as accurately as possible.

0056As a measure of the eligible frequency range, the rotational frequency ν_WAVE an axis AC1, AC2, wherein the still unknown size of the wheel diameter D must be taken into account.

0057According to Fig. 2, the rotational frequency of the axis AC1, AC2 by a rotational frequency sensor DFS, for example, arranged on the axis AC1, AC2, known, used for this purpose, electromagnetic rotational frequency sensor DES, can be determined. To detect accelerations of the bogie DRE normal to the rail plane SCE, an acceleration sensor BS1, BS2, BS3, BS4 is arranged in the region of each axle bearing AX1, AX2, AX3, AX4.

0058Furthermore, to detect accelerations of the bogie DRE in a plane parallel to the rail plane further sensors BS5, BS6, BS7 are provided on the bogie, the signal evaluation is described below. Assuming a smooth rolling, the vehicle speed V can be determined both via the threshold frequency ν_SF as well as the rotational frequency ν_WAVE the axis AC1, AC2 are determined:<maths id="math0002" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">V = ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> * D</mtext></mrow><mrow><mtext mathvariant="italic">S</mtext></mrow></msub></mrow></math><img file="EP1236633A2_D0002.tif" /></maths><maths id="math0003" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">V = ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub><mtext mathvariant="italic"> * D * π</mtext><mtext>,</mtext></mrow></math><img file="EP1236633A2_D0003.tif" /></maths>

0059Equating the two velocity expressions allows the relationship between the threshold frequency <i>ν</i>_<i>SF</i> and the rotational frequency ν_WAVE the axis AC1, AC2 are determined:<maths id="math0004" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub><mtext> = </mtext><mfrac><mrow><mtext mathvariant="italic">D</mtext><mtext> * Π * </mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub></mrow><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">s</mtext></mrow></msub></mrow></mfrac><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0004.tif" /></maths> this can be simplified in the form<maths id="math0005" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub><mtext> = α </mtext><msub><mrow><mtext mathvariant="italic">* Ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub><mtext> write, where</mtext></mrow></math><img file="EP1236633A2_D0005.tif" /></maths><maths id="math0006" num=""><math display="block"><mrow><mtext>α = </mtext><mfrac><mrow><mtext mathvariant="italic">D</mtext><mtext> * Π</mtext></mrow><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">s</mtext></mrow></msub></mrow></mfrac><mtext> was set.</mtext></mrow></math><img file="EP1236633A2_D0006.tif" /></maths>

0060In the case of an ICE-2 train, the tolerable range of the wheel diameter D is from 860 to 920 mm, resulting, for example, the following proportionality factors α for the relationship between the threshold frequency and the rotational frequency of the wheel axis as a function of the wheel diameter D and the threshold distance d_s result: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><i>d</i>_<i>S</i> /cm</entry><entry namest="col2" nameend="col2" align="center">D / cm</entry><entry namest="col3" nameend="col3" align="center">α</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">60</entry><entry namest="col2" nameend="col2" align="center">86</entry><entry namest="col3" nameend="col3" align="char" char=",">4.5</entry></row><row><entry namest="col1" nameend="col1" align="center">60</entry><entry namest="col2" nameend="col2" align="center">92</entry><entry namest="col3" nameend="col3" align="char" char=",">4.82</entry></row><row><entry namest="col1" nameend="col1" align="center">65</entry><entry namest="col2" nameend="col2" align="center">86</entry><entry namest="col3" nameend="col3" align="char" char=",">4.16</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">65</entry><entry namest="col2" nameend="col2" align="center">92</entry><entry namest="col3" nameend="col3" align="char" char=",">4.45</entry></row></tbody></tgroup></table></tables>

0061Referring to Fig. 3, in the case of the above example, the threshold frequency ν is frequency_SF in the spectrum of the amplitudes of the recorded in the axle storage acceleration signals SI1, SI2 between the fourth and fifth Radunrundheitsharmonischen RH4, RH5 and can be determined undisturbed by these. Radunural harmonics in this document are understood to mean forced periodic vibrations caused by deviations of the wheel cross-section from the circular shape. The fundamental harmonic of the Radunrundesharmoniker RH1 is exactly at the rotational frequency of the axis AC1, AC2.

0062The term harmonic is understood in this document spectral lines whose frequencies have an integer ratio to each other. This occurs in particular during the Fourier transformation of periodic, non-sinusoidal signals. The fundamental harmonic is the harmonic with the lowest frequency, which corresponds to the reciprocal of the period of such a signal. With her, the numbering begins with 1. All higher frequency harmonics ("harmonics") are numbered in this document according to their frequency ratio to the fundamental harmonic, i. H. the first harmonic is the second harmonic.

0063Based on the expected threshold distances in combination with the tolerable wheel diameters can be calculated from the formulas<maths id="math0007" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub><mtext>(</mtext><mtext mathvariant="italic">D</mtext><mtext>) = </mtext><mfrac><mrow><mtext mathvariant="italic">D</mtext><mtext>* Π *</mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub></mrow><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">s</mtext></mrow></msub></mrow></mfrac><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0007.tif" /></maths> and<maths id="math0008" num=""><math display="block"><mrow><mtext>Δν = Δ</mtext><mtext mathvariant="italic">D</mtext><mfrac><mrow><mtext>π *</mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub></mrow><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">s</mtext></mrow></msub></mrow></mfrac><mtext> With</mtext></mrow></math><img file="EP1236633A2_D0008.tif" /></maths><maths id="math0009" num=""><math display="block"><mrow><mtext>Δ</mtext><mtext mathvariant="italic">D</mtext><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">D</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext> - </mtext><msub><mrow><mtext mathvariant="italic">D</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0009.tif" /></maths> where D₁ the upper limit and D₂ the lower limit of the tolerable wheel diameter, the frequency range ν_SF (D₂) Δν for the search of the threshold frequency ν_SF be determined. In this case, integer multiples of the rotational frequency ν_WAVE with AC1, AC2 and a safety clearance except to avoid confusion with RH4, RH5 Radunural Harmonics.

0064Within the just defined frequency range ν_SF (D₂) Δν is determined, for example, the maximum, with some demands on the absolute value of the amplitude or the ratio of the amplitude to the noise level can be set to ensure a clear detection.

0065The basis for determining the wheel diameter D is the identity of the threshold frequency ν_SF determined travel speed V and from the rotational frequency ν_WAVE certain travel speed assuming a pure rolling motion. The wheel diameter D can after the determination of the exact threshold frequency ν_SF calculated using the formula:<maths id="math0010" num=""><math display="block"><mrow><mtext mathvariant="italic">D</mtext><mtext> = </mtext><mfrac><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">s</mtext></mrow></msub><mtext> * </mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub></mrow><mrow><mtext>π * </mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub></mrow></mfrac></mrow></math><img file="EP1236633A2_D0010.tif" /></maths>

0066For an exact determination of the travel speed V or the wheel diameter D is an accurate knowledge of the threshold distance d_s necessary. Since different standards exist, this quantity can not be regarded as a constant, but must be measured.

0067The method proposed here makes use for this purpose of the phase shift of the oscillation of two offset along the rail wheelsets whose geometric distance 1 is known exactly.

0068According to Fig. 4, the phases φ of the acceleration signals SI1, SI2 are shifted from each other. The cause of the phase shift Δφ can be seen in the fact that the distance 1 of the bearing surfaces of the wheels RA1, RA2, RA3, RA4 on the rails usually not exactly with an integer multiple of the threshold distance d_s matches. In the direction of travel FA1 to the left in FIG. 1, the second acceleration signal SI2 has a trailing phase position with respect to the first acceleration signal SI1. In the opposite direction of travel FA2, the sign is reversed, but also with a corresponding extension or shortening of the threshold distance d_s entry. To be able to distinguish these effects from one another, the direction of travel FA1, FA2 must be known, for example by forming the cross-correlation function of the two acceleration signals SI1, SI2, otherwise it is necessary to determine the existence of certain threshold distances d_s excluded.

0069To determine the phase difference Δφ, it is important that the phase angle φ the phase spectrum at the same frequency v - the threshold frequency ν_SF - Is taken. Theoretically, the two acceleration signals SI1, SI2 are identical and phase shifted with respect to the threshold harmonic.

0070To the threshold frequency ν_SF in the phase spectrum, the threshold frequency ν_SF for each acceleration signal SI1, SI2 determined from the amplitude spectrum and the arithmetic mean of these two values ​​formed. This mean value is then in the phase spectrum as threshold frequency ν_SF identifies and formed at this frequency, the phase difference Δφ the phase angle φ (SI1, SI2) of the two threshold frequency vibrations.

0071Since the phases are between -180 ° and + 180 °, the number of complete periods of the threshold beat oscillation in the area between the two wheels RA1, RA2, RA3, RA4 is unknown. This information must therefore be assumed.

0072Assuming a known number of complete periods N, the threshold distance can be determined <i>d</i>_<i>S</i> calculate at known distance 1 of the axes AC1 and AC2 by the following formula:<maths id="math0011" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">S</mtext></mrow></msub><mtext> = </mtext><mfrac><mrow><mtext mathvariant="italic">l</mtext><mtext>[</mtext><mtext mathvariant="italic">m</mtext><mtext>]</mtext></mrow><mrow><mtext mathvariant="italic">N</mtext><mtext>+</mtext><mfrac><mrow><mtext>Δφ [</mtext><mtext mathvariant="italic">wheel</mtext><mtext>]</mtext></mrow><mrow><mtext>2π</mtext></mrow></mfrac></mrow></mfrac><mtext>,</mtext></mrow></math><img file="EP1236633A2_D0011.tif" /></maths>

0073An assignment of different values ​​of complete periods N to some threshold intervals d_s can be done at a distance 1 of the axes AC1 and AC2, for example, 2.5 m as given below: <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><i>d</i>_<i>S</i>/cm</entry><entry namest="col2" nameend="col2" align="center">N</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">41.7 - 50.0</entry><entry namest="col2" nameend="col2" align="center">5</entry></row><row><entry namest="col1" nameend="col1" align="center">50.0 - 62.5</entry><entry namest="col2" nameend="col2" align="center">4</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">62.5 - 83.3</entry><entry namest="col2" nameend="col2" align="center">3</entry></row></tbody></tgroup></table></tables>

0074It is therefore necessary the area in which the threshold distance d_s a given distance is known to the exact threshold distance d_s to calculate this route.

0075Varies the threshold distance d_s between several areas, can be determined by the phase difference to the correct value of complete periods N and thus to the threshold distance d_s getting closed.

0076As already mentioned above, in order to obtain the correct sign of the phase difference, it is necessary to know the direction of travel of the rail vehicle. This fact also follows directly from the formula used to calculate the phase difference Δφ:<maths id="math0012" num=""><math display="block"><mrow><msub><mrow><mtext>Δφ = φ</mtext></mrow><mrow><mtext mathvariant="italic">in front</mtext></mrow></msub><msub><mrow><mtext> - φ</mtext></mrow><mrow><mtext mathvariant="italic">to</mtext></mrow></msub><mtext>,</mtext></mrow></math><img file="EP1236633A2_D0012.tif" /></maths>

0077In the case of the direction of travel FA1 corresponds to φ in the formula just mentioned_{in front} the phase angle of the acceleration signal SI1, which originates from the acceleration sensor BS1 situated in the direction of travel FA1 in front of the other acceleration sensor BSE, calculated threshold frequency oscillation and φ_to the phase angle of the threshold shake vibration associated with the acceleration signal SI2 received by the other acceleration sensor BS2.

0078Prerequisite for a clear assignment of the two sign ranges is, as already mentioned above, the knowledge of the direction of travel FA1, FA2. If this information is not available, it is still possible by limiting it to specifiable values ​​of the threshold distances d_s make a definite decision based on the absolute value of the phase difference of the threshold shake.

0079It has been shown that, due to the sensitivity of the method, even rotations of the bogie DRE relative to the rails - which corresponds to a shortening of the distance 1 of the axes AC1, AC2 - significantly affect the phase difference Δφ. Since the laying of the thresholds is very exact on average, the shortening of the distance 1 at a constant threshold distance d_s a greater influence on the acceleration signals SI1, SI2 as fluctuations of the threshold distance d_s, For this reason, the method described above is used only for detecting the respective laying standard, for the further calculations then the determined standard spacing is used.

0080According to FIG. 5, the acceleration signals SI1, SI2 recorded by the acceleration sensors BS1, BS2 and the rotational frequency signals DSI recorded by the rotational frequency sensor DFS are transmitted to an evaluation unit ASW. The transmission of the signals from the acceleration sensors BS1, BS2 and the rotational frequency sensor DFS to the evaluation ASW can be done by means of electrical lines, optical lines or wirelessly.

0081In the evaluation unit, signal values ​​of the acceleration signals SI1, SI2 which lie within a predefinable time interval / time window, for example 2.5 s, are subjected to a Fourier transformation FFT. On the concept of time-windowing, see E. Schrüfer "Signal Processing: Numerical Processing of Digital Signals" 2nd ed. - Munich; Vienna: Hanser 1992; P. 167 - p. 180.

0082Circuits and methods for performing a Fourier transformation, in particular a Fast Fourier transformation, are known to the person skilled in the art and are described, for example, in EP 402 145 and in "Speech Processing" by B. Eppinger and E. Herter; Hanser Verlag Munich Vienna 1993 pp. 68-71.

0083From each Fourier transform, the threshold frequency ν is calculated_SF and the phase angle φ of the threshold frequency oscillation determined.

0084Is the threshold distance d_s not known in advance, the phase difference Δφ of the threshold frequency oscillation associated with a front and a rear wheel is formed.

0085From the phase difference Δφ of the acceleration signals SI1, SI2, the threshold distance d_s calculated according to the method described above.

0086From the threshold frequency ν_SF Then, the calculation of the wheel diameter D according to the method just described.

0087For example, if the wheel rolls on the rail with the wheel flange, the rotational speed of the wheel / wheel set decreases according to the difference in diameter between the running surface and the flange edge, without the train speed varying significantly - the threshold frequency remains the same. However, since the rotational frequency ν_WAVE the wave changes, according to the formula already mentioned above<maths id="math0013" num=""><math display="block"><mrow><mtext mathvariant="italic">D</mtext><mtext> = </mtext><mfrac><mrow><msub><mrow><mtext mathvariant="italic">d</mtext></mrow><mrow><mtext mathvariant="italic">s</mtext></mrow></msub><mtext> * </mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">SF</mtext></mrow></msub></mrow><mrow><mtext>π * </mtext><msub><mrow><mtext mathvariant="italic">ν</mtext></mrow><mrow><mtext mathvariant="italic">wave</mtext></mrow></msub></mrow></mfrac></mrow></math><img file="EP1236633A2_D0013.tif" /></maths> a dergistered state of a change in the diameter D. Accumulation of the flange edge, as shown in Fig. 9 corresponds, for example, in an ICE train substantially an increase of the wheel diameter by 5% compared to a non-derailed state. FIG. 6 shows the course of the calculated diameter D of a wheel running on the rail and, in comparison to that in FIG. 7, the calculated diameter D of a wheel in the derailed / climbed state.

0088In order to determine a second characteristic KEN2, as already shown in FIG. 2, an acceleration sensor BS1, BS2, BS3, BS4 is arranged on the bogie DRE in the region of each axial bearing AX1, AX2, AX3, AX4.

0089About the rotational movement of a rigidly connected to an inner ring of a rolling bearing wheel axis vibrations are induced in the bogie during a journey of the rail vehicle. These vibrations can be measured in the form of local acceleration fluctuations at the axle bearings AX1, AX2, AX3, AX4 of the wheel axle, with selected vibration components, the so-called Radunrundesharmoniker, allow conclusions about a derailed condition.

0090As already mentioned above, the Radunrural Harmonics are forced periodic vibrations, which are caused by deviations of the wheel cross-section from the circular shape. The mechanism underlying the formation of radial health harmonics can be understood as follows: rolling the non-round wheels causes shocks of the bogie. A point on the running surface of the wheel is thereby rolled over at a time interval which corresponds to the reciprocal of the rotational frequency of the wheel axle. Damage / derailment of the tread therefore leads to a shock sequence with the rotational frequency of the wheel axle and induces a Radunrundheitsschwingung in the axle bearing of the wheel in question, whose fundamental frequency coincides exactly with the rotational frequency of the wheel axle. Due to the different shape of the contact points of (tidy) tread or Flange with the rail surface or other surface and the resulting different Radunrundesharmonon may be on a run-up of the flange to be closed a derailed state.

0091According to FIG. 8, from the Fourier transform of the acceleration signals SI1, SI2, SI3, SI4 in the evaluation unit ASW, the radial runtime harmonics RH0-RH10 are determined in the manner explained below.

0092The basic vibration or fundamental harmonic of the radial health harmonics RH0-RH10 lies in a spectral representation of the acceleration signals SI1, SI2, SI3, SI4, as already mentioned above, exactly at the rotational frequency of the wheel axis. For accurate determination of this rotational frequency, a rotational frequency sensor DFS can be arranged on the wheel axle.

0093In order to determine a derailed state, the mean value of the amplitudes of a predefinable number of radial wheel harmonics RH0-RH10 can be formed as second characteristic value KEN2 and compared, for example, with a predefinable setpoint value SOL2. Depending on the amount of deviation of this characteristic value KEN2 from the desired value SOL2, a conclusion can be drawn about a derailed state.

0094Another possibility is that value ranges or Values ​​of the characteristic value just mentioned corresponds to a specific stage of the derailment condition. A specific value / value range of the second characteristic KEN2 corresponds, for example, to a climbing up of the wheel flange SPK onto the rail head SKO according to FIG. 9, another value / value range of a wheel rolling on a concrete bed BET, as shown in FIG. 10 and 11, and again another value / value range is provided to an over-threshold wheel as shown in FIG. 12 and FIG. 13 shown. A direct comparison with a setpoint SOL is not necessary in this case.

0095In summary, to determine the second parameter KEN2, it can be said that, on the one hand, the flange SPK has a different profile than the running surface LAU of its wheel and that a sleeper superstructure, for example a concrete bed BET, offers a completely different running surface than the rail. These changes in roll geometry have a rapid impact on the spectrum.

0096In the case of a complete derailment, but also in the pre-critical state, according to FIG. 9 and FIG. 11 and FIG. 13, the normal operating contact point with respect to both the wheels and the rail head SKO thus changes the overall spectrum of the wheel harmonic and the threshold harmonic , A quick and singular change with respect to the bogie of the above sizes is recognized and reported as a derailed condition of a wheelset.

0097As shown in FIG. 14, the amplitudes A of the radial health harmonics RH0, RH2, RH3, RH4, RH5, RH6, RH7, RH8, RH9, RH10 have different heights. In the case of derailed wheel conditions, the associated wheel-radius harmonics RH0-RH10 have, on average, greatly increased amplitudes A, for which reason the abovementioned second characteristic value KEN2 for derailment detection increases with increasing derailment.

0098On the other hand, since the diameter of the flange is larger than that of the tread, there may be a shift of the wheel harmonic towards lower frequencies.

0099After determining the respective Radunrundessharmonischen whose phase angles are determined, the phase angles are taken from the Fourier transform of the acceleration signals. From the phase curves of the wheels associated acceleration signals, it can be concluded that a derailment of a wheel. The phase characteristic of the wheel harmonic of a derailed wheel differ substantially from that of a wheel running on the rail. Analogous to what has just been said, however, the progressions of the phase differences of the wheels of a wheelset can also be monitored.

0100Another method for derailment diagnosis is to perform the Fourier transform of the acceleration signals as shown in FIG. 15 The cepstrum is calculated according to the following formula KEP = iFFT (ln (FFT)), in which KEP the cepstrum iFFT means the inverse Fourier transform, FFT the fast Fourier transform of the acceleration signal and ln the natural logarithm - see "Digital Speech Processing" by Peter Vary et. al. Teubner-Verlag Stuttgart, 1998, pp. 68-69.

0101The spectrum according to FIG. 15 essentially corresponds to the spectrum according to FIG. 4, the spectral lines shown here also correspond here to a prescribable number of radial wheel harmonics. For illustrative reasons, however, numbering of the radial health harmonics in FIG. 15 has been dispensed with.

0102The cepstrum representation according to FIG. 16 contains the reciprocal of the wave frequency <i>ν</i>_<i>wave</i> of the wheel a peak, which corresponds to the average height of all Radunrundesharmonic from the considered frequency interval and thus allows a conclusion on the existence of a derailed condition.

0103To increase the accuracy of the derailment diagnosis, a third characteristic KEN3 can be formed. For this purpose, one starts from the consideration that the spectral representation of the vibration of a mechanical system can be considered as a product of the transfer function of that system with the excitation function. Thus, certain dominance regions of a spectrum - the regions of the resonant frequencies of the wheel - are subject to qualitative and quantitative change as the excitation changes significantly. These frequency intervals can be measured continuously, compared with one another and finally assessed. For the term transfer function, see E. Schrüfer "Signal Processing: Numerical Processing of Digital Signals" 2. Ed. - Munich; Vienna: Hanser 1992; Cape. 7, p. 263-271.

0104The term dominance ranges of a spectrum are those frequency intervals in which any broadband excitations due to design-related conditions (structural resonances = transfer function) cause stochastic, noise-like amplitude increases, which appear in the form of high-energy zones in the amplitude spectrum, as shown in FIG.

0105A derailment leads due to the wandered contact point on the part of the wheel in the direction of wheel flange and on the rolling mat, which is no longer the rail, but consists of sleepers and / or gravel or the concrete bed, to a sudden change in the shape of the excitation and thus a characteristic Change of dominance areas DOM of the affected wheel / pair of wheels. This change can be quantified in the form of characteristic value KEN3 and compared with a predefinable desired value and, if necessary, detected and reported as a degressed state of a pair of wheels.

0106In order to form this characteristic KEN3, according to FIG. 18 the acceleration signals recorded at the axle bearings are subjected in the evaluation unit to a Fourier transformation or another unitary transformation which maps the time domain of a signal onto the frequency domain. The dominance regions DOM are then determined from the spectrum of each signal. To form the characteristic values, the dominance regions DOM are compared with one another at different times of recorded spectra. If there is an exceeding of a tolerable deviation of the two dominance areas, then a message ALA is generated, which is displayed for example on an output unit AUS, and / or initiated an emergency braking.

0107A method for calculating a fourth characteristic KEN4, as shown in FIG. 22 illustrated, the consideration is based on that according to FIG. 19 and FIG. 20 In normal operation within predeterminable time intervals, the wheel sets - apart from emergency braking - are not exposed to significant fluctuations in the rotational accelerations. That would hardly be possible because of the high inertial masses of the car body and the bogie frame and the high moments of inertia of the coupled car body bogie system, since, inter alia, the energy quantities required for this are not available.

0108Now, according to Fig. 21 in the case of a derailment, the wheel's energy exchange with the new rolling pad, since both the rim and the new rolling pad, such as ballast, sleepers or concrete bed, are suitable for rolling less than the tread-rail system. The periodic abrupt contact of the derailed wheels with the thresholds is very energy-intensive and leads in the affected wheelset, among other things by the rapid change of sections of positive and negative spin to noticeable fluctuations in the rotational speed curve. These changing rotational accelerations are detected metrologically by means of the pole wheel and perceived by the evaluation unit under the condition that they occur unilaterally with respect to the bogie, as a feature of a derailment.

0109Referring to FIG. 22, the rotational frequency ν continuously detected by the rotational frequency sensor DFS becomes ν_WAVE a wheel axle or a wheelset forwarded to the evaluation ASW. The signal transmission to the evaluation unit ASW, as in the above-mentioned acceleration sensors SI1, SI2, SI3, SI4, via electrical lines, optical lines or wireless. The fourth characteristic KEN4 can, for example, by forming the second derivative of the course of the rotational frequency ν_WAVE be formed in a predetermined time interval. In the case of constant accelerations, as for example when starting or Braking may occur, the second derivative in the considered time interval is approximately zero. In the case of constant speed, of course, this also applies. In the case of acceleration fluctuations within the considered time interval, the second derivative does not disappear. In this case, it can be concluded that there is a derailed condition of the wheel / wheel set under consideration and a corresponding indication signal is generated and / or emergency braking is initiated. The differentiation of signals is for example in E. Schrüfer "Signal Processing: Numerical Processing of Digital Signals" 2. Ed. - Munich; Vienna: Hanser 1992; Cape. 4.2, p. 114 - 116 described.

0110In another embodiment for determining the fourth characteristic KEN4, the rotational frequency characteristics of all axes of a bogie can be compared. If there are major deviations in the course of events from one another, there is a derailed condition.

0111The calculation of a fifth characteristic KEN5, as shown in Fig. 24, can be carried out by means of a cross-correlation of those acceleration signals, which originate from two with respect to the longitudinal center plane λ equidistant wheels of two wheelsets and reflect the acceleration curve of the bogie normal to the rail plane.

0112The correlation analysis - be it cross-correlation or autocorrelation - makes it possible to identify periodicities of measured time signal segments or to check. Thus, if necessary, periodic events can be highlighted and stochastic components eliminated. In this case, two signal sections in the time domain with themselves - autocorrelation - or with each other - cross-correlation - multiplied by a certain algorithm and added taking into account the sign. For the concept of cross-correlation see E. Schrüfer "Signal Processing: Numerical Processing of Digital Signals" 2. Ed. - Munich; Vienna: Hanser 1992; Cape. 7, p. 235-262.

0113Is shown in FIG. 23 a cross-correlation function KKF of simultaneously recorded acceleration signals SI1, SI2, SI3, SI4 consecutively on the same rail moving wheels RA1, RA2, RA3, RA4 formed, in this way, a maximum MAX can be detected on the basis of the same excitation through the common roadway offset by the delay time τ, whose distance from the zero point of the cross-correlation function KKF the physical distance 1 two consecutive wheels RA1, RA2, RA3, RA4 at a certain speed corresponds. The value of this maximum MAX is a similarity feature of the two considered time signals.

0114The derailment of one of the monitored wheels causes the above-mentioned similarities of the routes traveled no longer exist. As a result, the maximum MAX can be reduced so much that it goes down in the noise of the signal. The one-sided disappearance of such a maximum with respect to a bogie or a strong variation of its position is regarded as a feature of a derailment and reported.

0115For derailment detection on threshold tracks, it is expedient, as shown in FIG. 24, to carry out a narrow bandpass filtering BAF by the threshold frequency in advance. In this case, in the non-derailed state, a large increase in the amplitude of the abovementioned maximum MAX is to be expected, which simplifies the characteristic value determination.

0116If the calculation of the cross correlation for the left and right side of the bogie is carried out simultaneously with signals coming from the left and the right side of the bogie, then the unilateral loss of the rail contact of a single wheel set can be detected.

0117One method for calculating a sixth characteristic KEN6 is to evaluate the plane-parallel movement of the turntable frame. For this purpose, the longitudinal acceleration is determined on both sides of the longitudinal center plane λ of the bogie and the lateral acceleration of the bogie.

0118The calculation of a sixth characteristic KEN6, as shown in FIG. 26 is based on the assumption that the derailment of at least one bogie axle significantly affects the dynamics and the kinematics of the bogie frame. The cause of this is to be found in the change of the roll underlay of the two wheels of the affected axle. The new base, be it concrete bed or sleeper, caused by their compared to the rail significantly worse rolling properties in the case of a concrete bed low-frequency rigid body vibrations and in the case of a threshold railway frontal shocks against the thresholds and lateral shocks against the rail edge, which by the primary suspension and Radsatzführung forwarded to the bogie frame. These suggestions quickly lead to a substantial change in the frame dynamics, which can be measured using the acceleration sensors described above and evaluated accordingly in the evaluation unit ASW.

0119As part of a first method for determining the sixth characteristic KEN6 only the accelerations in the longitudinal direction of the bogie frame, respectively measured on both sides of the longitudinal center plane λ, wherein the evaluation of the in Fig. 22 shown longitudinal acceleration signals SI5, SI6 in the time domain, d. h, the signals are not subjected to Fourier transformation. As a sign of a derailment of a bogie is one-sided occurrence of large rashes. This method is very well suited for detecting defied states on a threshold track.

0120A second method for determining the sixth characteristic KEN6 consists in the detection of the lateral acceleration signals SI7 transverse to the direction of travel in the middle of the bogie frame DGR. In this case, one-sided, excessively large lateral acceleration rashes are assigned as lateral impacts derailed wheels against the rail side.

0121Another more complex variant for the formation of the sixth characteristic KEN 6 consists in the analysis of the ratio of the rotation or Translational parts of the plane-parallel movement of the bogie frame. Also in this method, the acceleration signals are evaluated in the time domain. In the context of this method, according to a known solid-state mechanics approach, the assumed instantaneous plane-parallel movement of the bogie frame is decomposed into a translational and a rotational component on the basis of the superposition principle.

0122According to FIG. 25 let the rotational and the translational acceleration component be calculated from the acceleration signals recorded by acceleration sensors BS5, BS6, BS7. The longitudinal acceleration sensors BS5, BS6 are used to detect the longitudinal acceleration of the bogie DRE, which is why their effective direction extends substantially in the direction of travel FAR of the rail vehicle. In addition to the two acceleration sensors BS5, BS6 whose direction of action in the direction of travel FAR of the rail vehicle, a third acceleration sensor BS7 is provided, the direction of action in a plane parallel to the rail plane and normal to the direction of travel FAR of the rail vehicle. In this way, it is possible to uniquely determine the state of acceleration of the bogie DRE in a plane.

0123In this case, the amount of the resulting acceleration vector measured as left- or right-side longitudinal acceleration signal SI5, SI6 is composed as follows:<maths id="math0014" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">XLi</mtext></mrow></msub><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Tx</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> + a</mtext></mrow><mrow><mtext mathvariant="italic">Rx</mtext></mrow></msub><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0014.tif" /></maths><maths id="math0015" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Xre</mtext></mrow></msub><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Tx</mtext></mrow></msub><mtext> - </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Rx</mtext></mrow></msub></mrow></math><img file="EP1236633A2_D0015.tif" /></maths> and<maths id="math0016" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Y</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> = a</mtext></mrow><mrow><mtext mathvariant="italic">Ty</mtext></mrow></msub><mtext> + </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Ry</mtext></mrow></msub><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0016.tif" /></maths> mean here <i>a</i>_<i>XLi</i> and <i>a</i>_<i>Xre</i> the longitudinal accelerations SI5, SI6 measured on the left or right of the bogie frame, <i>a</i>_<i>Tx</i> and <i>a</i>_<i>Ty</i> the tangential component of the measured acceleration in the x and y directions, <i>a</i>_<i>Rx</i> and <i>a</i>_<i>Ry</i> the rotatory component in x-resp. in the y direction and<i>a</i>_<i>Y</i> the acceleration measured on the bogie frame normal to the rail plane and to the direction of travel in the form of a lateral acceleration signal SI7.

0124As can easily be seen, the equality of the translational components of the measured accelerations and the translational component of the bogie center SWP follows in the x and y directions. After a short calculation and forming one obtains for the translational component of the bogie center of gravity SWP<maths id="math0017" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Tx</mtext></mrow></msub><mtext> = </mtext><mfrac><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">XLi</mtext></mrow></msub><mtext> + </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Xre</mtext></mrow></msub></mrow><mrow><mtext>2</mtext></mrow></mfrac></mrow></math><img file="EP1236633A2_D0017.tif" /></maths> and<maths id="math0018" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Ty</mtext></mrow></msub><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Y</mtext></mrow></msub><mtext> - </mtext><mfrac><mrow><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">XLi</mtext></mrow></msub><mtext> - </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Xre</mtext></mrow></msub></mrow><mrow><mtext>2</mtext></mrow></mfrac><mtext> * </mtext><mfrac><mrow><mtext mathvariant="italic">la</mtext></mrow><mrow><mtext mathvariant="italic">b</mtext></mrow></mfrac><mtext>.</mtext></mrow></math><img file="EP1236633A2_D0018.tif" /></maths> where la is the distance of one of the acceleration sensors BS5, BS6 for measuring the longitudinal acceleration of the bogie frame DRE of a plane of symmetry σ of the bogie, which is normal to the longitudinal center plane λ and b is the distance of a longitudinal acceleration sensor BS5, BS6 for measuring the longitudinal acceleration of the longitudinal center plane λ. The lateral acceleration sensor BS7 may be disposed at an arbitrary position of the bogie frame DGR. It is only important that its effective direction is normal to the effective direction of the longitudinal acceleration sensors BS5, BS6.

0125For the rotational acceleration ε of the bogie center SWP results<maths id="math0019" num=""><math display="block"><mrow><mtext>ε = </mtext><mfrac><mrow><mtext>1</mtext></mrow><mrow><mtext>2</mtext><mtext mathvariant="italic">b</mtext></mrow></mfrac><mtext>(</mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">XLi</mtext></mrow></msub><mtext> - </mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext mathvariant="italic">Xre</mtext></mrow></msub><mtext>)</mtext></mrow></math><img file="EP1236633A2_D0019.tif" /></maths>

0126From the comparison of the time courses of the calculated translational and rotational components of the acceleration of the bogie center of gravity conclusions can be drawn regarding the stability of the bogie frame DGR. In order to facilitate the detection of a derailed state, the sixth characteristic value KEN 6 is formed on the basis of the calculated acceleration characteristics. For this purpose, the translational and rotational acceleration of the bogie center of gravity SWP can be calculated within a predefinable time interval, the ratio of successive, calculated acceleration profiles being formed. If this ratio exceeds or this sixth characteristic KEN6 a setpoint SOL6 by a predetermined amount, it can be concluded that a derailed condition. This is possible because the acceleration curves deviate greatly from their original shape in the event of a derailment.

0127Of course, any other method to compare the calculated acceleration signals with each other, for example by subtraction, etc, possible.

0128In all methods for calculating the sixth characteristic KEN6 is shown in FIG. 26 a low-pass filtering performed. This ensures that only the vibration components which correspond to the rigid body dynamics remain from the overall spectra of the acceleration signals - higher-frequency components belonging to the acoustic range are filtered out in the process. For the term of filtering, see for example E. Schrüfer "Signal Processing: Numerical Processing of Digital Signals" 2. Ed. - Munich; Vienna: Hanser 1992; S. 180- S. 234th

0129From the synopsis of the calculated characteristic values ​​KEN1-KEN6, it can be concluded with great certainty whether a degassed state is present or not. For example, the presence of setpoint overshoots of two characteristics KEN1-KEN6 indicates that there is a derailment. In this way, track-related false alarms about derailment conditions can be avoided, which also leads to a higher acceptance of rail vehicles, which are equipped with a device according to the invention.

0130In order to conclude a derailed state from all characteristic values ​​KEN1-KEN6, in the evaluation unit ASW according to FIG. 27 For example, a multi-dimensional state space are formed whose dimension corresponds to the number of calculated characteristic values ​​KEN1-KEN6. As decision limits for the classification into the two classes "not derailed" and "derailed" as many limits can be selected as there are characteristic values. In the simplest case, these limits / setpoints run linearly. By considering the calculated characteristic values ​​KEN1-KEN6, a comprehensive and exact determination and analysis of derailed states of a rail vehicle or a group of rail vehicles can be achieved.

0131With a suitable choice of the limits / setpoints SOL1-SOL6, a dangerous derailment situation or a pre-critical derailment condition is recognized at a very early stage and, for example, reduced by a reduction in the speed of travel. Furthermore, it can be provided that when one or more setpoint values ​​SOL1-SOL6 are exceeded, the indication signal ALA is transmitted to a control unit STR, which is connected to the brakes of the rail vehicle and causes emergency braking.

0132Of course, the method described above may be performed online using known, appropriately programmed microprocessors. The skilled person is also aware of numerous programs or programming languages ​​that are suitable for implementing the method according to the invention, for example Mathematica, Matlab etc.

0133In summary, it can be said that the susceptibility to error of the method according to the invention or the device according to the invention compared to the known methods and devices by the simultaneous calculation of different characteristics for derailment detection significantly reduced and greatly improved in terms of accuracy and reliability.