Rotary encoder for detecting impurities and train having a rotary encoder

Abstract

The present invention relates to a rotary encoder for detecting an acceleration acting independently of a rotational movement of a rail wheel rotatable on a rail section, comprising rotation detection means designed such that the rotational movement of the rail wheel and / or a wheel axle comprising two rail wheels can be detected by at least one rotation position signal.According to the invention, the rotary encoder comprises acceleration detection means designed such that an acceleration acting on the rail wheel, in particular the wheel center, independently of the rotational movement, can be detected by at least one acceleration signal, as well as fault detection means designed such that the at least one acceleration signal can be monitored for at least one abnormality, preferably at least one transient signal peak, particularly preferably a positive and / or negative increase in the amplitude of the acceleration signal, and most preferably a directed and / or impulse-like acceleration, in order to detect a fault in the rail wheel and / or in the rail section.

Description

[0001] The present invention relates to a rotary encoder for a rotating rail wheel.

[0002] Furthermore, the present invention relates to a train according to claim 12.

[0003] Rotary encoders for detecting a rotational movement of a rail wheel rotatable on a rail section are generally known, e.g. from US 2012 / 259487 A1.

[0004] Such rotary encoders are used to detect the rotational movement of a rail wheel or a wheel axle comprising two rail wheels and generate an analog or digital rotational position signal that represents the rotational movement of the rail wheel. In addition to the speed of the monitored rail wheel, the rotational direction and the rotational acceleration acting on the rail wheel can also be determined in real time from the rotational position signal. The rotational position signal is often fed into a control loop to specifically influence the rotational movement via a drive unit based on a setpoint.

[0005] A disadvantage of known encoders is that defects in the rail wheel and / or the rail section cannot be detected, which is why the rail wheels have to be measured on a test bench using separate measuring technology.

[0006] Therefore, it is the object of the present invention to overcome the disadvantages known from the prior art. In particular, it is the object of the present invention to provide a rotary encoder which, in addition to exclusively detecting a rotary movement of a rail wheel rotatable on a rail section, can also make a statement about the state and / or condition of the rail wheel and / or the rail section. Furthermore, it is also the object of the present invention to specify a train which comprises a corresponding rotary encoder in order to detect the state and / or condition of a rail wheel of the train and / or of a rail section on which the train runs during rotating operation of the rail wheel, i.e. during train operation.

[0007] This object is achieved by a rotary encoder having the features of claim 1. Furthermore, the object is achieved by a train with a rotary encoder according to the invention.

[0008] Advantageous developments of the invention are described in the subclaims. The scope of the invention includes all combinations of at least two of the features disclosed in the description, the claims, and / or the figures.

[0009] The present invention relates to a rotary encoder for detecting an acceleration acting on a rail wheel, in particular on the wheel center, independently of any possible rotational movement of the rail wheel. In other words, the rotary encoder is designed to detect the acceleration acting on a rail wheel independently of any rotational movement of the rail wheel on a rail section. Such an acceleration is generated, in particular, by a force acting on the rail wheel that acts in the vertical direction and / or along the vertical and is thus oriented orthogonally to a horizontal direction and / or the horizontal.

[0010] The rotary encoder according to the invention comprises rotation detection means which are designed and / or configured such that the rotational movement of the rail wheel and / or of a wheel axle comprising two rail wheels can be detected by at least one rotational position signal.

[0011] Furthermore, the rotary encoder according to the invention comprises acceleration detection means configured such that an acceleration acting on the rail wheel independently of the rotational movement, preferably acting on the wheel center and particularly preferably in the vertical direction, can be detected by at least one acceleration signal. In other words, the acceleration detection means are configured to detect a force acting in the vertical direction and / or along a vertical axis, which acts on the wheel center and results in an acceleration of the wheel center in the vertical direction.

[0012] Furthermore, the rotary encoder according to the invention comprises fault detection means which are designed such that the at least one acceleration signal can be monitored for at least one abnormality in order to detect a fault in the rail wheel and / or in the rail section.

[0013] For the purposes of the present invention, an abnormality can be formed by a transient signal peak, i.e., a short-term signal excursion, in the acceleration signal. An abnormality can also be formed by a positive and / or negative increase in the amplitude of the acceleration signal and / or by a directed and / or pulse-like acceleration. Furthermore, an abnormality can be a single signal peak or multiple, particularly high-frequency and / or immediately consecutive, signal peaks.

[0014] Preferably, the fault detection means for detecting an abnormality are configured such that the acceleration signal is detected and / or evaluated over several full revolutions of the rail wheel in order to detect an abnormality in the signal curve.

[0015] Particularly preferably, the defect detection means for detecting an abnormality are configured for averaging to detect acceleration values ​​of the rail wheel averaged from the acceleration signal and to detect an abnormality in the averaged acceleration values.

[0016] Most preferably, the fault detection means for detecting an abnormality are configured to monitor the acceleration values ​​or the averaged acceleration values ​​for exceeding a threshold value. The threshold value can be a static value that can be manually specified based on empirical values. Alternatively, the threshold value can also be dynamically determined, for example, to assess the signal peak with respect to the previous course of the acceleration signal, in particular by averaging.

[0017] The rotational position signal represents the rotational movement of the rail wheel and / or preferably encodes, particularly in conjunction with an absolute rotary encoder with absolute rotation detection means, a rotation angle sub-range in contact with the rail section as a function of a time base and / or a clock generator. The rail wheel is preferably divided into a plurality of rotation angle sub-ranges.

[0018] The rotational position signal, which can be generated by the rotation detection means, is preferably embodied as an analog or digital signal. Particularly preferably, the rotational position signal encodes and / or describes a plurality of rotational positions of the rail wheel.

[0019] By deriving the rotational position signal over time, a speed signal of the rail wheel can be formed. By deriving the speed signal, an acceleration signal of the rail wheel can be generated. This acceleration signal relates to the rotational movement of the rail wheel and thus acts essentially independently of the acceleration signal detectable by the acceleration detection means according to the invention.

[0020] The rotational position signal is preferably evaluated to monitor the rotational movement of the rail wheel. In addition to exclusively monitoring the rotational movement, the rotational position signal can also be used as an input variable of a control loop to influence the rotational movement of the rail wheel according to a setpoint specification via a drive unit. It is also particularly preferred if the rotational position signal is in the form of two rectangular signals, whereby the speed and direction of rotation of the rail wheel can be determined from the frequency and phase position of these rectangular signals.

[0021] The acceleration detection means are operatively connected to the rail wheel and / or the wheel axle. In a rotating operating state of the rail wheel, i.e., in a state in which the rail wheel rotates on the rail section at any rotational speed other than zero, the rotational movement of the rail wheel does not directly affect a vertically acting acceleration that can be detected by the acceleration detection means. The acceleration detection means are thus preferably mounted in a substantially stationary manner on a support unit, in particular a wheel bearing housing.

[0022] The fault that is detected in the rail wheel by evaluating the acceleration signal within the scope of the present invention can be a flat spot in the rail wheel.

[0023] A defect in the rail section can be formed by a horizontal and / or vertical offset between two rail elements that together form the rail section. Such a defect in the rail section is referred to in the present invention as a rail joint and / or a rail transition.

[0024] In a further development, it is provided that the rotation detection means and the acceleration detection means are operatively connected to one another in such a way that an acceleration value of the acceleration signal can be assigned to a rotation position of the rotation position signal.

[0025] In other words, the rotation detection means and the acceleration detection means comprise a common clock and / or timer, which is why any acceleration value of the acceleration signal can be assigned a corresponding rotational position of the position signal. Advantageously, the acceleration acting on the rail wheel can thus be detected and / or analyzed depending on the rotational position of the rail wheel.

[0026] According to a further development, the defect detection means comprise monitoring means which are designed to evaluate the acceleration signal as a function of the rotational position signal in such a way that a rotationally position-fixed defect can be detected as a flat spot in the rail wheel and / or a rotationally position-independent defect can be detected as a rail joint and / or rail transition in the rail section.

[0027] By evaluating the acceleration signal as a function of the rotational position signal over at least two full revolutions of the rail wheel in the rotating operating state, the faults detected by an abnormality in the acceleration signal can be more precisely identified. Advantageously, such an evaluation can identify a rotationally fixed fault as a fault in the rail wheel and thus as a flat spot, and a rotationally independent fault as a fault in the rail section and thus as a rail joint and / or rail transition.

[0028] In a further development of the present invention, the defect detection means comprise analysis means with a plurality of summation elements, wherein the number of summation elements corresponds to a predeterminable number of rotation angle sub-ranges in order to divide the rail wheel, in particular evenly, to represent a full rotation. The analysis means for determining the severity of flat spots and for detecting a possible flat spot are designed such that, in a rotating operating state of the rail wheel, i.e., in particular, during train operation, acceleration values ​​are assigned to a rotation angle sub-range via the assigned rotation position and are added to form a sum in the corresponding summation element of the assigned rotation angle sub-range.

[0029] By evaluating the calculated sums, in particular by comparing them with the remaining sums of the remaining rotation angle sub-ranges, the extent of a flat spot in the rail wheel can be advantageously determined for a specific rotation angle sub-range. Furthermore, by evaluating the sums, in particular by comparing them with the remaining sums of the remaining rotation angle sub-ranges, the presence of a flat spot in the rail wheel can also be detected.

[0030] Within the scope of the present invention, it was advantageously recognized that with increasing development of the flat spot in the rail wheel, the acceleration values ​​acting in the vertical direction for the corresponding rotational positions also increase, which is why the largest sum of acceleration values ​​can be formed in the rotational angle sub-ranges in which the flat spot is formed and / or which contain the corresponding rotational positions.

[0031] The largest sum of a rotation angle subrange always results from all sums of the remaining rotation angle subranges that completely represent the rail wheel. Furthermore, it is important to ensure that the sums being compared were calculated using an identical number of summands or were averaged over the number of summands before the comparison.

[0032] A rotation angle sub-range of the plurality of rotation angle sub-ranges can preferably be pie-shaped and / or span an angle of preferably 1° or 360 / 2", where the exponent n is an integer and greater than zero, particularly preferably 2°, very particularly preferably 4°. Alternatively, the plurality of rotation angle sub-ranges can also be of different sizes, i.e. each span a first and at least one second angle.

[0033] The individual acceleration values, which are continuously added together in the summation element to form a sum, can also be negative, particularly due to measurement variation and / or measurement noise. Therefore, the absolute values ​​of the sums of the individual summation elements do not necessarily increase continuously with the addition of further summands. In other words, with an increasing number of full revolutions taken into account when calculating the individual sums, the sums do not necessarily increase continuously.

[0034] When evaluating the calculated sums to determine the extent of the flat spot, the sums of all summation terms may be considered. If a sum with the largest absolute value is identified for a rotation angle sub-range or for several immediately adjacent rotation angle sub-ranges, the extent of a flat spot can be advantageously determined for this rotation angle sub-range or for these immediately adjacent rotation angle sub-ranges.

[0035] Furthermore, it was recognized within the scope of the present invention that the ratio or difference between the amount of the largest sum and the amounts of the remaining sums serves as a measure for determining the extent of the flat spot.

[0036] With an increasing number of full revolutions, which are taken into account by the analysis tools by adding the recorded acceleration values ​​to the sums of the summation elements, the risk of incorrect detection of a flat spot can be reduced, since in particular unevenness in the rail section is filtered out.

[0037] In a further development, it is provided that the analysis means for determining the characteristic and for a first detection of a possible flat spot are designed and / or arranged in such a way that the amount of the mean value of the respective sum of all summation elements, in particular the respective sum divided by the number of summands added up and the amount thereof, is determined and the largest mean value is determined from the mean values ​​of all summation elements.

[0038] In this context, it should be noted that this largest mean value is used as a measure of the extent of the potential flat spot, and the rotation angle subrange associated with the largest mean value is recorded and / or stored as an indicator for the initial detection of the potential flat spot. Furthermore, it is preferably provided that the largest mean value is output as a first output signal. Advantageously, an average acceleration value can thus be determined from the individual sums.

[0039] Within the scope of a further development of the aforementioned embodiment, the analysis means for further detection are designed such that the scatter, in particular the standard deviation, is formed over a plurality of continuously recorded indicators, in particular previously determined largest mean values, wherein a small scatter is assigned a high probability of occurrence and a large scatter is assigned a low probability of occurrence as a criterion for detecting a flat spot, and in particular the probability of occurrence is output as a second output signal.

[0040] In this context, it is particularly preferred if a histogram is used and the mean acceleration values ​​are assigned to the rotation positions, whereby abnormalities and / or defects, in particular flat spots, are detected by analyzing the characteristic distribution of the histogram, which is based on the constructive superposition of rotation-periodic amplitude peaks and on the destructive superposition of random amplitudes.

[0041] In this case, the individual indicators, each calculated by averaging over several full revolutions, are reanalyzed and evaluated in such a way that the variance, particularly the standard deviation, is determined for a large number of the successively calculated indicators. This advantageously further reduces the risk of false detection when detecting a flat spot.

[0042] Furthermore, in a further development of the present invention, the analysis means are designed to generate a maintenance indicator such that the maintenance indicator is formed from the characteristic, in particular the previously determined largest mean value, and the probability of occurrence, in particular by multiplication, in order to transmit this maintenance indicator, in particular by means of a third output signal, to an external evaluation unit. Advantageously, this further improves the determination of the characteristic of a flat spot, since defects detected due to an uneven rail section are not recognized as flat spots and / or are only output as flat spots with a low characteristic.

[0043] In a further preferred embodiment of the rotary encoder according to the invention, the rotary encoder comprises calibration means. These calibration means are designed such that, in a calibration state, which can be automatically activated, in particular after the rotary encoder is switched on and / or after a stationary operating state of the rail wheel is detected by evaluating the rotational position signal, the mounting orientation of the rotary encoder, in particular a mounting angle β of the rotary encoder between a detection axis and a vertical axis, can be detected by the acceleration detection means by detecting and evaluating the acceleration signal in order to compensate for the influence of the mounting angle on the acceleration signal by detecting the force of gravity and / or the gravitational acceleration g.

[0044] Advantageously, the influence of the mounting angle, which depends on the alignment and / or mounting, on the acceleration detection means can thus be determined in order to use the acceleration detection means to detect only the acceleration and / or force component acting on the wheel center point which acts in the vertical direction.

[0045] In other words, the calibration means can be used to determine calibration parameters for the acceleration detection means, which enable compensation of the acceleration signal such that the acceleration signal only encodes and / or maps the acceleration acting in the vertical direction and / or along the vertical axis. This can advantageously improve the detection of a defect in the rail wheel and / or the rail section.

[0046] In a further development, it is also provided that the acceleration detection means are designed such that the acceleration acting on the rail wheel and / or the wheel axle can be detected two-dimensionally or three-dimensionally, in particular along an X and Y axis or along an X, Y and Z axis, which are each aligned orthogonally to one another, and / or that the acceleration detection means are designed as a micromechanical acceleration sensor and / or a MEMS.

[0047] The acceleration signal is thus preferably designed as a vector in order to encode the acceleration acting on the wheel center in different directions.

[0048] In a further preferred embodiment, the rotary encoder comprises a magnetically or optically or mechanically coded measuring tape, wherein the rotation detection means are designed such that a relative movement between the measuring tape, which can be fixed in particular on an outer circumference of the wheel axle, and the rotation detection means, which can be fixed in particular substantially stationary relative to the wheel axle and to a wheel housing, can be detected, wherein the rotation position can be represented continuously or discretely by the rotation position signal.

[0049] A mechanically coded measuring tape is preferably formed by a ferromagnetic gear that is mechanically torsionally rigidly coupled to the rail wheel or the wheel axle in order to detect the rotational movement via the gear.

[0050] Furthermore, it is further provided that the rotary encoder comprises maintenance means, wherein the maintenance means are designed such that upon detection of a disturbance, in particular a flat spot in the rail wheel and / or a rail joint in the rail section, a maintenance signal can be generated, which can be transmitted in particular via communication means to a maintenance center. In this context, not only the maintenance signal is preferably transmitted, but also additional information about the disturbance. In the case of a flat spot, such information can be the rotational position and / or the shape of the flat spot, and in the case of a rail joint, the position of the rail joint in the rail section encoded by integrating the position signal.

[0051] Finally, within the scope of the present invention, protection is also claimed for a train with at least one wheel axle comprising two rail wheels, wherein the train and / or the wheel axle comprises at least one rotary encoder according to the invention for monitoring the rotational movement of a rail wheel.

[0052] The invention is explained in more detail below by way of example with reference to the drawings. The combination of features presented as examples in the embodiments shown can be supplemented by further features in accordance with the above explanations, depending on the properties of the sensor unit according to the invention required for a specific application. Individual features can also be omitted from the described embodiments if the effect of this feature is not important in a specific application.

[0053] In the drawings, elements with the same function and / or structure are designated by the same reference numeral.

[0054] It shows in Fig. 1 is a schematic representation of a rotary encoder according to the invention in accordance with a first exemplary embodiment, in Fig. 2 is a schematic block diagram of the rotary encoder according to the invention in accordance with a second exemplary embodiment, in Fig. 3 is a schematic block diagram of the rotary encoder according to the invention in accordance with a third exemplary embodiment, in Fig. 4 is an exemplary curve of the acceleration signal, in Fig. 5 is a schematic representation of the rotary encoder according to the invention in the mounted state on a wheel axle of a chassis, in Fig. 6a / b is a schematic representation to illustrate a defect in the rail section and in Fig. 7a / b is a schematic representation to illustrate a defect and / or flat spot in the rail wheel.

[0055] The Fig. 1 shows a schematic representation of a rotary encoder 1 according to the invention according to a first preferred embodiment.

[0056] The rotary encoder 1 according to the invention is designed to detect an acceleration BV which acts on the wheel center M independently of the rotational movement R of the rail wheel 3 and which is aligned along the vertical direction V and / or parallel to a vertical axis V.

[0057] The rotary encoder 1 according to the invention initially comprises conventional rotation detection means 4, which are designed such that the rotational and / or rotary movement R of the rail wheel 3 and / or the rotational movement of a wheel axle comprising two rail wheels 3 can be detected and coded and / or mapped by at least one rotational position signal P(t).

[0058] Furthermore, the rotary encoder 1 according to the invention comprises acceleration detection means 5, which are designed such that an acceleration acting on the rail wheel 3, i.e. in particular on the wheel center M of the rail wheel 3, independently of the rotational movement, can be detected and represented by at least one acceleration signal.

[0059] Furthermore, the rotary encoder 1 according to the invention comprises fault detection means 6 which are designed such that the at least one acceleration signal B v (t) can be monitored for at least one abnormality in order to detect a fault in the rail wheel 3 and / or a fault in the rail section 2.

[0060] Such an abnormality is preferably a transient acceleration peak formed in the course of the acceleration signal B v (t), which affects the wheel center point M of the rail wheel 3 along the vertical direction V.

[0061] The rotary encoder 1 according to the invention further comprises a magnetic measuring tape 15, which is operatively connected to the rotation detection means 4 for detecting the rotational movement. For this purpose, the rotation detection means 4 are configured such that a relative movement between the measuring tape 15, which is attached to an outer circumference of the wheel axle, and the rotation detection means 4, which can be fixed substantially stationary relative to the wheel axle and to a wheel housing, can be detected. The rotational position is represented continuously or discretely by the rotational position signal and, in a rotating operating state of the rail wheel 3, has a sawtooth-shaped curve, since the signal is incremented step by step from zero after completing a full rotation, i.e., a 360° rotation.

[0062] In the Fig. 2 a highly schematic block diagram of a rotary encoder 1 according to the invention according to a second embodiment is shown.

[0063] The rotary encoder 1 according to the invention according to the second embodiment comprises, in addition to the rotation detection means 4 already mentioned in connection with the known rotary encoder 1, the acceleration detection means 5 and the disturbance detection means 6, additional monitoring means 7.

[0064] The monitoring means 7, which are included in the fault detection means 6, are designed to evaluate the acceleration signal as a function of the rotational position signal. In this case, the rotation detection means 4 and the acceleration detection means 5 comprise a common clock generator, so that the corresponding, i.e., synchronously detected, acceleration value from the acceleration signal can be assigned to a detected rotational position of the rotational position signal.

[0065] Advantageously, the detection of defects can thus be further improved, since the temporal alignment between the acceleration signal and the rotational position signal for at least two full revolutions allows a defect to be characterized as either rotationally fixed or rotationally independent. Advantageously, when a rotationally fixed defect is detected, a flat spot formed in the rail wheel 3 can be detected, and when a rotationally independent defect is detected, the defect can be identified as a rail joint in rail section 2.

[0066] In the Fig. 3 a highly schematic block diagram of a further rotary encoder 1 according to the invention according to a third embodiment is shown.

[0067] This embodiment of the rotary encoder 1 again comprises the already known rotation detection means 4, the acceleration detection means 5 and the disturbance detection means 6.

[0068] In the present case, the acceleration detection means 5 are formed by a micromechanical acceleration sensor 14 which can detect the acceleration acting on the wheel center M in three dimensions, wherein in the present case only the acceleration acting in the vertical direction V is referred to as the acceleration signal.

[0069] Furthermore, this rotary encoder 1 comprises analysis means 8 comprising a plurality of summation elements 9a-c. The number of summation elements 9a-c depends on a predeterminable number of pie-shaped rotation angle subranges 10a-c that completely subdivide the rail wheel 3, with only three summation elements being shown as examples in the block diagram.

[0070] Furthermore, the analysis means 8 are designed such that, in a rotating operating state of the rail wheel 3 on the rail section 2, acceleration values ​​from the acceleration signal can be assigned to one of the rotation angle sub-ranges 10a-c via the temporally corresponding rotation position from the rotation position signal and are added together to form a sum in the corresponding summation element 9a-c.

[0071] By evaluating the individual sums, in particular those formed over several full revolutions, not only can a flat spot in the rail wheel 3 be detected but also a statement can be made about the extent of the flat spot in the rail wheel 3.

[0072] The analysis means 8 are designed to determine the extent of the flat spot and for the first detection of a possible flat spot in such a way that the absolute value of the mean value of the respective sum is formed from all summation elements 9a-c.

[0073] Then, from all the sums, the sum whose mean value is the largest with respect to the remaining mean values ​​is selected, and this mean value is then output as a measure to indicate the severity of the flat spot.

[0074] Furthermore, the rotation angle sub-range associated with the largest mean value is output as an indicator for a first, in particular preliminary, detection of a possible detected flat spot together with the largest mean value as a first output signal 11.

[0075] In addition, the analysis means 8 for further detection are preferably configured such that the scatter is determined over a plurality of continuously detected indicators, wherein, as a criterion for detecting a flat spot, a high probability of occurrence is assigned to a low scatter and a low probability of occurrence is assigned to a high scatter, wherein the probability of occurrence is output as a second output signal 11a.

[0076] Furthermore, analysis means 8 for generating a maintenance indicator are preferably designed such that the maintenance indicator is formed from the characteristic, in particular the largest mean value, and the probability of occurrence, in particular by means of multiplication, and the maintenance indicator is transmitted to an external evaluation unit (not shown graphically) by means of a third output signal 11b.

[0077] The rotary encoder 1 also includes maintenance means 16, which are operatively connected to a central maintenance unit (also not shown) via a communication link (not shown). The maintenance unit receives faults detected by the rotary encoder 1 and can thus adjust maintenance intervals as needed.

[0078] Finally, the rotary encoder 1 of the third embodiment also comprises calibration means 13, which are Fig. 5 be explained in more detail.

[0079] The Fig. 4 shows, by way of example, the time course of the detected acceleration signal B v (t) in a rotating operating state of the rail wheel 3, wherein the acceleration signal was generated by a rotary encoder 1 according to the invention.

[0080] The acceleration signal B v (t) represents the acceleration acting on the wheel center M in the vertical direction V, wherein the vertical direction V is orthogonal to the horizontal direction H. In the embodiment according to the Fig. 5 the illustrated rail section 2 runs along the horizontal direction (see the Fig. 5 ).

[0081] From the signal curve it can be seen that the acceleration signal B v (t) is composed of negative and positive acceleration values, whereby it should be noted that the signal curve is superimposed by the gravitational acceleration.

[0082] Furthermore, the curve shows that the acceleration signal BV includes transient signal peaks, i.e. directed acceleration peaks that are indicated by a positive and negative increase in the acceleration signal.

[0083] Furthermore, the diagram also includes the temporal progression of the rotational position signal P(t), which has a sawtooth-shaped progression. From the progression of the rotational position signal P(t), it is evident that the monitored rail wheel 3 moves and / or rotates at a constant speed in the graphically displayed section.

[0084] By means of the inventive adjustment and / or comparison between the course of the acceleration signal B v (t) with the course of the rotational position signal P(t), it can be seen that the abnormality formed by the acceleration peak X repeats itself in a rotational position-fixed manner or, in other words, is always detectable at the same position in the rail wheel and / or in the same rotational angle sub-ranges, which is why the abnormality is a defect in the rail wheel 3 and thus a flat spot.

[0085] In the Fig. 5 a side schematic view of a bogie 12 of a train 17 not shown in detail is shown.

[0086] The bogie 12 comprises two adjacent axes of rotation, each of which essentially rigidly connects two opposing rail wheels 3. The two axes of rotation comprise rotary encoders 1 according to the invention, which are mounted on the outer wheel housing and are thus essentially fixed to the bogie 12 and / or train 17. The rotary encoder 1 according to the invention comprises the rotation detection means 4 according to the invention (not shown in detail), the disturbance detection means 6 according to the invention, and the acceleration detection means 5 according to the invention.

[0087] Furthermore, it can be seen from the illustration that the two rotary encoders 1 are each mounted pivoted at a mounting angle β from the horizontal H and / or the horizontal direction H, which must be taken into account when detecting the acceleration BV acting in the vertical direction V, since the detection axis E of the respective acceleration detection means 5 is also pivoted by the respective mounting angle β.

[0088] For this reason, the two rotary encoders 1 comprise the calibration means 13 (not shown in detail), which are configured such that in a calibration state, which can be activated after the detection of a rest position by evaluating the rotation position signal of the rotation detection means 4 from the calibration means 13 and / or the rotary encoder 1 of the rail wheel 3, the influence of the attachment and / or mounting angle β on the acceleration detected by means of the acceleration detection means 5 can be determined by detecting the force of gravity and / or the gravitational acceleration g.

[0089] Advantageously, calibration data can thus be generated which can then be used to correct the acceleration signal in order to obtain the acceleration component acting on the wheel center M along the vertical direction V.

[0090] The Fig. 6a / b each show, again in a highly schematic manner, a defect in rail section 2, which is formed by a rail joint in rail section 2.

[0091] A rail joint can occur between a first rail element and a second rail element if the two rail elements are spaced apart from each other along the horizontal direction H and / or if the two rail elements form a step along the vertical direction V.

[0092] Such a disturbance also leads to an abnormality in the course of the acceleration signal B v (t), which is why such a disturbance can be detected by means of the rotary encoder 1 according to the invention.

[0093] To illustrate such rail joints, the Figuren 6a / b three temporally successive positions of the rail wheel S1-3 as well as the course of the movement line B(t) of the wheel center M.

[0094] In the Fig. 6a the fault is formed by a horizontal offset between two rail elements in a rail section 2.

[0095] The position S1 of rail wheel 3 occurs immediately before reaching the rail joint. At this point in time, no vertical acceleration is present.

[0096] At position S2, rail wheel 3 is located in the center of the disturbance. This is indicated by the achievement of maximum acceleration in the vertical direction V. The motion line B(t) reaches its minimum at S2.

[0097] At position S3, rail wheel 3 has completely overcome the rail joint. The acceleration in the vertical direction V has dropped back to zero, and the original level of the motion line B(t) has been reached again.

[0098] In the Fig. 6b the fault is formed by a horizontal offset between two rail elements in a rail section 2.

[0099] From the course of the sketched movement line B(t) of the wheel center M it can be seen that such a rail joint leads to an acceleration peak which is expressed by a permanent change and / or increase in the movement line B(t).

[0100] The Fig. 7a / b illustrate a flat spot formed in a rail wheel 3.

[0101] From the Fig. 7a It can be seen that the flat spot in the rail wheel 3 is formed over a circular segment at a central angle ϕ with respect to the wheel center M in the running surface of the rail wheel 3 and / or on the circumference of the rail wheel 3. The flat spot has a depth h. Furthermore, the rail wheel 3 has a radius r.

[0102] Through the Fig. 7b the course of the movement line B(t) of the wheel center M of the rail wheel 3 as well as three temporally successive positions S1-3 of the rail wheel 3 according to the Figuren 6a / b schematically shown. The angle of rotation α is derived from the Fig. 7a out.

[0103] The motion line B(t) can be determined from the acceleration signal B v (t).

[0104] The illustrated position S1 corresponds to the position of rail wheel 3 immediately before the transition into the flat spot area. Position S2 shows the rail wheel position at a time when the flat spot is fully in contact with rail section 2. Position S3 shows the rail wheel position immediately after the transition from the flat spot area.

[0105] It is noted that the line of motion B(t) of the wheel center M of the rail wheel 3 can be described as follows (compare the figures Fig. 7a / b, where in the Fig. 7a α = 0°). 0 < α ≤ φ 2 : r ∗ sin α r ∗ cos α φ 2 < α ≤ φ : l + r ∗ sin α − φ r ∗ cos α − φ φ < α ≤ 0 : l + r ∗ α − φ r

[0106] The angle of rotation α of the rail wheel 3 depends on the angular frequency and the time, whereby the angular frequency can be determined in particular from the rotation position signal and the time, which is why a speed position signal and an acceleration position signal can be determined for the wheel center M.

[0107] It should be noted that the movement sequence shown does not take into account dynamic effects due, among other things, to the inertia of the masses of the rail wheel 3 and the energy stored in the wheel suspension.

Claims

1. Rotary encoder (1) for detecting acceleration acting on a rail wheel (3) that is rotatable on a rail section (2), independent of a rotational movement, comprising: Rotation detections means (4), which are configured in such a way that the rotational movement of the rail wheel (3) and / or a wheelset axle comprising two rail wheels (3) is detectable by at least one rotational position signal, whereby acceleration detection means (5) are comprised by the rotary encoder (1) and are configured in such a way that an acceleration acting independently of the rational movement on the rail wheel (3), particularly on the wheel's center point, is detectable by at least one acceleration signal, and fault detection means (6), which are configured in such a way that the at least one acceleration signal is monitored for at least one abnormality, preferably at least one transient signal peak, more preferably a positive and / or negative amplitude overshoot in the acceleration signal, and most preferably a directional and / or pulse-like acceleration, to detect a fault in the rail wheel (3) and / or the rail section (2).

2. Rotary encoder according to Claim 1, characterized in that the rotation detections means (4) and the acceleration detection means (5) are operatively connected such that an acceleration value of the acceleration signal, particularly one acting on the wheel's center point, can be assigned to a rotational position of the rotational position signal.

3. Rotary encoder according to Claim 2, characterized in that the fault detection means (6) comprise monitoring means (7) configured to evaluate the acceleration signal based on the rotational position signal, in such a way that a fault location that is fixed in the rotational position can be identified as a flat spot on the rail wheel (3), and / or a rotational-position-independent fault location can be identified as a rail joint or rail transition in the rail section (2).

4. Rotary encoder according to Claim 2, characterized in that the fault detection locators (6) include analysis tools (8) with multiple summation elements (9a-c), whereby the number of summation elements (9) corresponds to a predeterminable number of rotational angle subranges (10), to divide the rail wheel (3) into segments representing a full rotation, preferably evenly distributed, whereby the analysis tools (8) are configured such that when the rail wheel (3) is in a rotating operational state, acceleration values corresponding to the rotational position are assigned to a rotational angle subrange (10a-c) and added up in the respective summation element (9a-c) to form a sum, whereby these sums are evaluated to determine the characteristics of flat spots and to detect the flat spots.

5. Rotary encoder according to Claim 4, characterized in that the analysis tools (8) for determining the characteristic and a first detection of a potential flat spot are designed in such a way that the amount of the mean value of the respective sum, in particular the respective sum divided by the number of summands and the amount thereof, is determined from all summation elements (9a-c), and the largest mean value is determined from the mean values of all the summation elements and this mean value is assigned as a measure for the characteristics of the potential flat spot, and the rotational angle subrange associated with the largest mean value is recorded as an indicator for the initial detection of the potential flat spot and, in particular the largest mean value is output as a first output signal (11).

6. Rotary encoder according to Claim 5, characterized in that the analysis tools (8) for further detection are designed such that the dispersion, particularly the standard deviation, is determined over multiple continuously detected indicators, a high probability of occurrence being assigned to a low dispersion and a low probability of occurrence being assigned to a high dispersion as a criterion for detecting a flat spot and, in particular, the probability of occurrence is output as a second output signal (11a).

7. Rotary encoder according to Claims 5 and 6, characterized in that the analysis tools (8) for generating a maintenance indicator are configured such that the maintenance indicator being formed from the characteristics, in particular the largest mean value, and the probability of occurrence, in particular by means of multiplication and the maintenance indicator is transmitted to an external evaluation unit, in particular by means of a third output signal (11b).

8. Rotary encoder according to any of the preceding claims, characterized in that the rotary encoder (1) comprises calibration means (13), whereby the calibration means (13) are configured such that in a calibration state, which can be automatically activated, in particular after the encoder (1) is powered on and / or after detecting a stationary operating state of the rail wheel (3) by evaluating the rotational position signal, the mounting orientation of the encoder (1), particularly a mounting angle (β) of the encoder (1) between a detection axis (E) and a vertical axis (V), can be detected by means of the acceleration detection means (5) by detecting and evaluating the acceleration signal, in particular acceleration values, in order to compensate for the influence of gravitational force on the acceleration signal.

9. Rotary encoder according to any of the preceding claims, characterized in that the acceleration detection means (5) are configured such that the acceleration acting on the rail wheel (3) and / or the wheelset axle can be detected in two dimensions or three dimensions, particularly along the X-, Y-, and Z-axis, which are oriented orthogonally to each other, and / or the acceleration detection means (5) are configured as a micromechanical acceleration sensor (14) and / or an MEMS.

10. Rotary encoder according to any of the preceding claims, characterized in that the rotary encoder (1) comprises a magnetically or optically or mechanically coded measurement tape (15), whereas the rotation detections means (4) are configured in such a way that a relative movement between the measurement tape (15), in particular fixable to an outer circumference of the wheel axle, and the rotation detections means (4), in particular fixable substantially stationary to the wheel axle and to a wheel housing, is detectable, whereby the rotational position is mappable continuously or discretely by the rotational position signal.

11. Rotary Encoder according to any of the preceding claims, characterized in that the rotary encoder (1) comprises maintenance means (16), whereby the maintenance means (16) being configured in such a way that when a flat sport and / or a rail joint is detected, a maintenance signal can be generated which can be transmitted to a maintenance center in particular via communication means.

12. Train (17) comprising at least one wheelset axle, whereby the wheelset axle includes a rotary encoder (1) according to any of the preceding claims.

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