Method and device for approximating an acceleration signal plot, detected when a railbound vehicle travels via a measurement route, to the characteristic features of a corresponding force signal plot

Abstract

The invention relates to a method and device for approximating an acceleration signal plot a(t), detected when a railbound vehicle travels via a measurement route (1, 1', 1''), to the characteristic features of a corresponding force signal plot F(t). The measurement route (1, 1', 1'') is in the form of a rail (3) with at least one acceleration sensor (11) with the acceleration signals a thereof being transferred to an electronic evaluation unit (13) for receipt and processing. According to the invention, the following method steps are carried out: a) determining the acceleration signal plot a(t) resulting from the vertical wheel forces F acting on the measurement route (1, 1', 1'') when it is travelled, by continuously detecting the acceleration a by means of the at least one acceleration sensor (11); b) filtering the acceleration signal plot a(t) determined in step a) with a high-pass filter and a low pass filter or a band-pass filter; and c) numerically integrating the acceleration signal plot filtered in step b). The device according to the invention is characterised in that the electronic evaluation unit (13) is designed for carrying out the above-mentioned steps a) to c).

Description

[0001] Method and device for approximating an acceleration signal curve recorded during the passage of a rail-bound vehicle over a measuring section to the characteristic features of a corresponding force signal curve

[0002] field of technology

[0003] The invention relates to a method for approximating an acceleration signal curve a(t) detected during the passage of a rail-bound vehicle over a measuring section to the characteristic features of a corresponding force signal curve F(t) according to the preamble of claim 1 and to a device for carrying out the method according to the preamble of claim 7.

[0004] State of the art

[0005] The treads of the wheels of rail-bound vehicles are of crucial importance with regard to ride comfort and safety of rail transport, as the static and dynamic forces occurring during travel are transmitted into the rails via the treads and wheel flanges. Ideally, the geometry of the treads corresponds to a slightly conical surface concentrically surrounding the wheel axle, with which the wheels roll on the rails. The treads thus form the rotating part of the wheel-rail contact. Deviations from the ideal circular shape, for example due to uneven wear, material and manufacturing defects, and the like, are referred to as out-of-roundness. These include, among other things, singular out-of-roundness such as flat spots, flattening and material build-up, as well as periodic out-of-roundness such as eccentricities, ovalities and polygonization.Especially at high speeds, out-of-roundness increases the dynamic component of the forces exerted by the wheels on the rail. As a result, there is a risk that the peak force limits specified by the track operator will be exceeded, resulting in damage to the track and rolling stock. Further negative impacts include safety risks, noise emissions, and ground vibrations.

[0006] Therefore, there has been no shortage of efforts to identify wheels affected by out-of-roundness on a rail vehicle as early as possible. In addition to manually measuring the geometry of a wheel using gauges on a stationary vehicle, which is particularly useful when performing other maintenance and repair work due to the associated time expenditure, it is also already known to detect out-of-roundness on a wheel while the rail vehicle is passing over a measuring track equipped with sensors.

[0007] For example, EP 1 212 228 B1 already discloses a method and device for detecting out-of-roundness and flat spots on rail vehicle wheels. In this method, the vertical forces acting on the rails are recorded within a predefined measuring section using multiple force transducers. The force transducers are designed as load cells arranged between the rails and stationary sleepers over a length of at least one wheel circumference. As the vehicle travels over the measuring section, an electronic evaluation device calculates an average weight load from the vertical force signals and compares this with the signal curve over time. If a predefined deviation is exceeded, an out-of-roundness or flat spot is indicated. In this way, out-of-roundness and flat spots can be detected very reliably.However, since the detection is based on a force signal curve, this method involves relatively high investments for the construction of the measuring section due to the necessary force transducers.

[0008] EP 0 282 615 A1 describes an arrangement for detecting wheel damage using accelerometers extending linearly along a rail. The linear accelerometers measure the acceleration transmitted from the wheel to the rail at any point along their length. The individual measurement signals obtained in this way are subjected to an evaluation procedure to obtain information about the extent of wheel damage. Characteristics that provide information about the type and severity of the wheel damage are filtered out from the measurement signal using suitable frequency filter stages and / or an FFT analysis. The disadvantage of this approach is that it only provides a rough measurement result. Furthermore, it is not possible to determine the level of load on the track during the passage.

[0009] Furthermore, EP 1 883 565 A1 discloses a method for detecting the wheel shapes of rail vehicle wheels using a measuring section formed by a series of measuring elements attached to the rails. The wheel loads acting on the measuring elements generate force-proportional electrical signals, which are fed to an electronic evaluation device for evaluation. In the evaluation device, an information array is generated from the signals derived from the measuring elements, which correspond to the movement of the rail in the vertical direction and preferably also in the transverse direction. This information array represents at least one wheel circumference. The information array is composed of several information cells, whereby the respective signal components of different information cells can be continuously combined and relevant signal components evaluated.

[0010] Brief summary of the invention

[0011] Based on this prior art, the invention seeks to provide a method and device for determining the out-of-roundness of a wheel of a rail-bound vehicle in an economical, reliable, and highly accurate manner. A further object of the invention is to be able to make quantitative statements about the wheel loads underlying the acceleration signal curve from an existing acceleration signal curve.

[0012] These objects are achieved by a method having the features of claim 1 and a device having the features of claim 7.

[0013] Advantageous embodiments emerge from the subclaims.

[0014] The invention is based on the idea of ​​drawing conclusions about the corresponding force signal curve F(t) from the acceleration signal curve a(t) recorded when a rail vehicle travels over a measuring section, without the need for additional recording. The corresponding force signal curve F(t) is the unknown or only partially known force signal curve F(t) that is the cause of the recorded acceleration signal curve a(t), i.e., the basis for it.

[0015] Since more precise information about the mass-spring system formed by the track superstructure, substructure, and rail vehicle is generally not available, a purely mathematical conversion of the acceleration signal curve a(t) to the corresponding force signal curve F(t) is not possible. The invention is particularly effective in providing a solution for approximating the force signal curve F(t) based on the corresponding acceleration signal curve a(t), even without knowledge of this information.

[0016] The inventive solution provides for filtering the acceleration signal curve a(t) recorded by a measuring path, whereby signal components below a lower cutoff frequency fi and above an upper cutoff frequency fH are blocked or strongly attenuated. Filtering both adjusts the acceleration signal curve a(t) to the measurement technology and prepares it for numerical integration. For this purpose, a device according to the invention comprises suitable low-pass and high-pass filters or a corresponding bandpass filter.

[0017] For further approximation, the acceleration signal curve a'(t) obtained in this way is numerically integrated, which can be performed using electronic data processing in a suitable evaluation unit. After the numerical integration is complete, the acceleration signal curve a"(t) is so close to the corresponding force signal curve F(t) that sufficiently qualified statements can be made about the state of wear and the need for repair of a wheel. For example, above-average maximum and minimum values ​​in the amplitude of the numerically integrated acceleration signal curve a"(t) can indicate wheel runout, or the actual circumference of a wheel and thus its state of wear can be deduced based on consistent repetitions in the acceleration signal curve a(t).

[0018] When evaluating the acceleration signal curve a"(t) obtained according to the invention, it proves particularly advantageous that known and proven algorithms for evaluating force signals can be used. Therefore, no additional effort is required for the creation and testing of suitable software.

[0019] Since measuring sections equipped with force transducers require significantly higher investments than measuring sections with acceleration transducers, the invention represents a particularly interesting alternative from an economic point of view, especially for operators of track systems.

[0020] In order to prevent damage to track systems, compliance with limit values ​​for the wheel contact forces F is of great importance. In order to be able to derive quantitative statements about the existing wheel contact forces F from the integrated acceleration signal curve a"(t), in an advantageous development of the invention the acceleration signal curve a"(t) is calibrated on the basis of known wheel contact forces F. According to a preferred embodiment of the invention, this can be done by scaling the acceleration signal curve a"(t) by multiplying the individual values ​​of the acceleration signal curve a"(t) by a uniform factor k and thus adapting them to the force signal curve F(t). The factor k can be stored in the evaluation unit as a fixed value for a specific rail vehicle type.Alternatively, it is possible to determine the factor k as the rail vehicle passes over the measuring section, which can increase the accuracy of the approximation of the integrated acceleration signal curve a"(t). This requires that at least part of the measuring section is equipped with force transducers that record the corresponding force signal curve F(t) during or after the acquisition of the acceleration signal curve a(t). Corresponding individual values ​​or sections of the two signal curves a"(t) and F(t) can be related in this way, so that the factor k can be determined according to the relationship: k = a" / F or k = a"(t) / F(t).

[0021] A suitable measuring section is advantageously divided into a first measuring section equipped with force transducers and a second measuring section with accelerometers. The first measuring section and the second measuring section can overlap, for example, if the second measuring section with the accelerometers extends over the entire length of the measuring section, and the second, in comparison, shorter measuring section only extends over a longitudinal section of the measuring section. In this embodiment of the invention, the acceleration signal a and force signal F are recorded simultaneously, so that a subsequent calibration of the integrated acceleration signal curve a(t) can be carried out based on the actual wheel contact forces. With this procedure, extremely reliable values ​​for the wheel contact force F can be derived from the acceleration signal curve a(t) obtained by numerical integration.

[0022] In another embodiment of the invention, the first partial measuring section and the second partial measuring section follow one another in the direction of the rail track. Since both partial measuring sections are shorter than the total measuring section, the full length of the measuring section is only determined by combining the two partial measuring sections. This embodiment is particularly suitable when a measuring section with force transducers for determining wheel contact forces is already available, and its functionality is to be expanded with regard to the condition of the wheels of a rail vehicle. However, new measuring sections can also be implemented economically using this embodiment of the invention.

[0023] Without being limited thereto, the invention will be explained in more detail below with reference to exemplary embodiments illustrated in the drawings, wherein further features and advantages of the invention will become apparent. Where possible, identical reference numerals are used for identical and functionally equivalent features of different embodiments.

[0024] Short description of the drawings

[0025] It shows

[0026] Fig. 1 is an oblique view of a first embodiment of an apparatus according to the invention for carrying out a method according to the invention,

[0027] Fig. 2 shows the time course of the acceleration signal a detected by the device according to Fig. 1,

[0028] Fig. 3 is an oblique view of a second embodiment of a device according to the invention for carrying out a method according to the invention,

[0029] Fig. 4a shows the time course of the force signal F recorded with the device according to Fig. 3,

[0030] Fig. 4b shows the time course of the acceleration signal a detected by the device according to Fig. 3,

[0031] Fig. 5 is an oblique view of a third embodiment of an apparatus according to the invention for carrying out a method according to the invention,

[0032] Fig. 6a shows the time course of the force signal F recorded with the device according to Fig. 5,

[0033] Fig. 6b shows the time course of the acceleration signal a detected by the device according to Fig. 5, and

[0034] Fig. 7 shows the temporal progression of an acceleration signal a, a', a" at different times during the implementation of the method according to the invention in comparison with the corresponding force signal progression F. Description of the embodiments

[0035] Fig. 1 shows a first embodiment of a device according to the invention for carrying out the method according to the invention with a measuring section 1 for recording and evaluating the acceleration a that occurs during the passage of a rail-bound vehicle over the measuring section 1. In a simplified representation, one can see a section of a rail track 2 designed as a measuring section 1 with two rails 3 running parallel to one another, which are supported by a plurality of sleepers 4. The mutual distance between the sleepers 4 is in a range of approximately 600 mm to 700 mm. The rail track 2 is traveled over by a rail-bound vehicle at a speed v, for example a passenger or freight wagon, for which only the wheels 5 of a wheelset axle (not shown in detail) are shown as representative.The direction of travel of the rail-bound vehicle is denoted by x, the wheel contact force exerted by a wheel 5 on a rail 3 is denoted by F.

[0036] The measuring section 1 extends over a length L, which in the present embodiment corresponds to at least 1.2 times the wheel circumference U of the wheels 5 of the vehicles traveling on the rail track 2, preferably 1.5 times, most preferably 2 times. With a standard wheel diameter of approximately 1250 mm, this results in a length L of at least 4710 mm, preferably at least 5888 mm, most preferably 7850 mm.

[0037] In the area of ​​the measuring section 1, a measuring device for recording the acceleration a exerted on the rail 3 by a rolling wheel 5 is integrated into the rail track 2. The measuring device initially comprises two lateral force transducers 6, 7 arranged on each rail 3, one of which is installed at the beginning and the other at the end of the measuring section 1. These can be, for example, measuring eyes or strain gauges that record the shear stresses induced by the wheels 5 in the rails 3 in analog form and convert them into digital measurement signals. The lateral force transducers 6, 7 are used in this embodiment for the optional determination of the wheel contact forces. Alternatively, the lateral force transducers 6, 7 can be used as switches for the start and end of the measuring process of the measuring device and / or for axle detection and vehicle identification. In addition, as shown in Fig.2, the travel speed v in the area of ​​the measuring section 1 can be determined by means of the lateral force transducers 6, 7, which can be determined on the basis of the known distance of the lateral force transducer 6 from the lateral force transducer 7 in the direction of travel x and the known time period T, which corresponds to the difference between the rollover times U and t. In addition, the measuring device comprises acceleration transducers 11 for recording the acceleration a. The acceleration transducers 11 are each fastened between two sleepers 4 on the underside of the rails 3, which results in a mutual distance between the acceleration transducers 11 in the direction of the rail track 2, which corresponds to one sleeper spacing, but can also be greater and can correspond, for example, to twice the sleeper spacing.

[0038] The transverse force sensors 6, 7 and acceleration sensors 11 are connected via data lines 12 to an electronic evaluation unit 13, in which data storage and processing take place. To implement the method according to the invention, the evaluation unit 13 can, for example, have high-pass, low-pass, and / or band filters to filter the acceleration signal, and / or calculation algorithms can be executed in the evaluation unit 13, by means of which a numerical integration of the acceleration curve a(t) takes place. The data from a measurement process or the results of the evaluation are transmitted to a higher-level central location via radio or another data line 14. It is also possible to carry out the data processing partially or entirely at the higher-level central location.

[0039] Fig. 2 shows the time course of the acceleration signal a measured by the acceleration sensors 11 during the crossing of the measuring section 1. The rolling over of the lateral force sensor 6 by the wheel 5 corresponds to the time tA at which the measuring process by the measuring device begins. The rolling over of the lateral force sensor 7 by the same wheel 5 defines the time tE, which defines the end of the measuring process. The time period T lying between the times tA and tE corresponds to the duration of the crossing of the measuring section 1. With a known spatial distance between the lateral force sensors 6, 7, which in the present embodiment corresponds to the length L of the measuring section 1, the driving speed v of the rail vehicle can be determined according to the relationship: v = L / T, where T = (t E - t A )

[0040] The amplitude of the acceleration signal a oscillates around the value zero at a high frequency, depending on the quality of the running surface of the wheel 5. Significant deviations from this fluctuation range are the first acceleration maximum 16 or first acceleration minimum 17 of the acceleration signal curve a(t), which indicate an out-of-roundness of the running surface of the wheel 5. The time of the first occurrence of the first acceleration maximum 16 or first acceleration minimum 17 is denoted by ti.

[0041] Due to the specified length L of the measuring section 1, which is greater than the wheel circumference U, the wheel 5 rolls a second time within the measuring section 1 with at least a portion of its circumference U while the measurement process continues. As the wheel 5 rolls again on the rail 3, an acceleration signal curve a(t) is generated, the characteristic features of which correspond to those of the previous acceleration signal curve a(t). The most striking repetition is the second acceleration maximum 16' and the second acceleration minimum 17' at time t2, which, based on their amplitude and shape, can be assigned to the first acceleration maximum 16 and the first acceleration minimum 17, respectively. The time period Δt between times t1 and t2 corresponds to the time it takes the wheel 5 to roll once over its circumference U. In conjunction with the known driving speed v, the circumference U of the wheel 5 can be determined using the relationship:

[0042] U = v * At with At = t2 - ti

[0043] The acceleration signal curve a(t) recorded by the measuring device forms the basis for carrying out the method according to the invention, in which the acceleration signal curve a(t) is approximated to the force signal curve F(t) underlying the acceleration signal curve a(t), which is explained in more detail in Fig. 7.

[0044] A second embodiment of a device according to the invention is the subject of Figs. 3, 4a and 4b. The measuring section T shown in Fig. 3 corresponds to the measuring section 1 described in Fig. 1, supplemented by a partial measuring section 1.1 for recording the wheel contact force F in the area of ​​the partial measuring section 1.1. To avoid repetition, with regard to the rail track 2, the measuring section T with lateral force sensors 6, 7, acceleration sensors 11, data lines 12, evaluation unit 13, etc., reference is made to the above statements, which apply accordingly.

[0045] The partial measuring section 1.1 extends over a length L1 which is shorter than the length L of the measuring section 1' and, in the present exemplary embodiment, corresponds at least to the simple wheel circumference U of the wheels 5 of the vehicles traveling on the rail track 2. With a standard wheel diameter of approximately 1250 mm, this results in a length of at least 2925 mm. The measuring section 1' and partial measuring section 1.1 overlap in the direction of travel x, with a common beginning defined by the lateral force transducers 6. The first partial measuring section 1 .1 ends after the length L1 with the lateral force transducers 8, while the measuring section T continues up to the lateral force transducers 7, which mark the end of the measuring section 1'.

[0046] In the area of ​​the partial measuring section 1.1, the measuring device also includes transverse force transducers arranged on the rails 3, which can correspond to the transverse force transducers 6 at the beginning of the partial measuring section 1.1 and to the transverse force transducer 8 installed there at the end of the partial measuring section 1.1. Additional transverse force transducers 9 can be arranged between them, the distance between which corresponds, for example, to one or two times the sleeper spacing. As already described, the transverse force transducers 6, 8, 9 are preferably measuring eyes or strain gauges that record the shear stresses induced by the wheels 5 in the rails 3 in analog form and convert them into digital measurement signals.

[0047] Like the transverse force transducers 6, 7, the transverse force transducers 8, 9 serve to correct the force shunt to compensate for interference from adjacent rail sections. In this way, the partial measuring section 1.1 is segmented into smaller measuring sections. Transverse force transducers 6, 7, 8, 9 can also be used to determine the wheel contact force F.

[0048] In addition, force transducers 10 for detecting the wheel contact force F are provided in the area of ​​the first partial measuring section 1.1, for example, load beams, load cells, or weighing discs. In order to obtain a force signal that is as uniform as possible over the length of the partial measuring section 1.1, in the present embodiment, a force transducer 10 is arranged between each sleeper 4 and each rail 3, resulting in a mutual spacing of the force transducers 10 in the direction of the rail track 2 corresponding to one-time sleeper spacing. Furthermore, embodiments in which the spacing between successive force transducers 10 in the direction of travel x corresponds to twice or three times the sleeper spacing are also within the scope of the invention.

[0049] As already described in the first embodiment, the lateral force transducers 6, 7, 8, 9 and the force transducers 10 are connected by means of data lines 12 to an electronic evaluation unit 13 in which data storage and processing take place. The data from a measurement process and, if necessary, their evaluation are transmitted to a higher-level central location via radio or another data line 14. As can be seen from Figs. 4a and 4b, at time tA both the recording of the wheel contact force F by means of the force transducers 10 and the recording of the acceleration a by means of the acceleration transducers 11 begin simultaneously. Accordingly, in this embodiment of the invention, the force signal curve F(t) over the length L1 is recorded simultaneously with the acceleration signal curve a(t).

[0050] Fig. 4a shows the time course of the force signal F measured by force transducers 10 when passing over the partial measuring section 1.1, which begins with the wheel 5 rolling over the lateral force transducer 6 and ends at the time tx at which the wheel 5 rolls over the lateral force transducer 8 and thus leaves the area of ​​the first partial measuring section 1.1.

[0051] The amplitude of the force signal F oscillates more or less strongly around a value corresponding to the static load component F s tat corresponds to the force F exerted by a wheel 5 on a rail 3. Significant deviations from the fluctuation range are the force maximum 14 and force minimum 15 at time ti, which, due to their gradient and amplitude, indicate an out-of-roundness on the running surface of the wheel 5.

[0052] The acceleration signal curve a(t) shown in Fig. 4b corresponds to that described in Fig. 2, so reference is made to what was said there to avoid repetition. It should be noted that an out-of-roundness on the running surface of a wheel 5 at the same time t1 leads to maximum values ​​14, 15 in the force signal curve F(t) and to maximum values ​​16, 17 in the acceleration signal curve a(t).

[0053] In this embodiment of the invention, an approximation of the acceleration signal curve a(t) recorded by the measuring device to the force signal curve F(t) underlying the acceleration signal curve a(t) is carried out on the basis of the acceleration signal curve a(t) in combination with the force signal curve F(t), which will be explained in more detail in the description of Fig. 7.

[0054] Finally, Figs. 5 and 6 show an embodiment of the invention in which the measuring section 1" in the direction of the rail track 2 is composed of a first partial measuring section 1.1 of length L1 and a second partial measuring section 1.2 of length L2, which merge seamlessly into one another in the direction of travel x. The first partial measuring section 1.1 with force transducers 10 is similar to that described in Fig. 3, so that the explanations there apply accordingly.

[0055] The second partial measuring section 1.2 with the acceleration sensors 11 has a structural design that is fundamentally similar to the measuring section 1 described in Fig. 1, so that the statements made there apply accordingly. A key difference, however, is that the length L2 of the second partial measuring section 1.2 is significantly shorter than the length L of the measuring section 1. The length L2 of the second partial measuring section 1.2 can be shorter than the length L1 of the first partial measuring section 1.1, as in the present embodiment, or even longer than the length L1 of the first partial measuring section 1.1. In both cases, the first partial measuring section 1.1 and the second partial measuring section 1.2 together form the measuring section 1". At the beginning of the measuring section 1", shear force transducers 6 are arranged on the rails 3, and at the end of the measuring section 1", shear force transducers 7 are arranged. Additional shear force transducers 8 are located in the transition area between the first partial measuring section 1.1 and the second partial measuring section 1.2 and optionally in the area of ​​the partial measuring section 1.1 in order to divide it into smaller sections as previously shown in Fig. 3.

[0056] When a rail vehicle passes over the measuring section 1", a force signal curve F(t) is recorded over the length L1 in the area of ​​the first partial measuring section 1.1 starting at time tA, for which the force maximum 14 and force minimum 15 are characteristic, as already described in Fig. 4a. Upon reaching the end of the first partial measuring section 1.1 and at the beginning of the second partial measuring section 1.2 as the vehicle rolls over the lateral force transducers 8 at time tx, the recording of the acceleration signal a begins over the length L2 of the second partial measuring section 1.2, which results in the acceleration curve a(t) shown in Fig. 6b with the acceleration maxima 16 and acceleration minima 17. The measuring process ends when the wheels 5 pass over the lateral force transducers 7 at the end of the measuring section 1".

[0057] For the evaluation of the combined force / acceleration curve, the acceleration signal curve a(t) is approximated to the force signal curve F(t) underlying the acceleration curve a(t) using the method according to the invention, which is explained in more detail below with reference to Fig. 7. The result is a continuous force signal curve F(t), which can be used for further evaluation.

[0058] Based on Fig. 7, the various process steps for approximating the acceleration signal curve a(t) as shown in Fig. 7a to the underlying force signal curve F(t) are explained below. This curve is the subject of Fig. 7d and is intended to be reproduced as closely as possible by stepwise processing of the acceleration signal curve a(t). The data processing required for this purpose can take place entirely or partially in the evaluation unit 13, or entirely or partially at a higher-level location to which the necessary data is transmitted for this purpose.

[0059] Fig. 7a shows the acceleration signal curve a(t), as recorded, for example, when a rail vehicle travels over a measuring section 1, 1' by means of its accelerometer 11. Due to the high frequency of the oscillating acceleration signal a, qualified conclusions about the associated force signal curve F(t) (see Fig. 7d) are not readily possible. Nevertheless, exceptional deviations from the average acceleration signal curve a(t) can be seen in the area of ​​the first maximum 16 and first minimum 17 at time t1, which are due to an out-of-roundness of the wheel 5. Due to the length L of the measuring section 1, 1', which is greater than the circumference U of the wheel 5, these maximum values ​​are repeated in the form of the maximum 16' and minimum 17' at time t2 when the wheel 5 rolls again over the measuring section 1, 1'.2, which differs from measuring sections 1 , T only by its shorter length L2, this applies accordingly.

[0060] In a first method step, the acceleration signal curve a(t) shown in Fig. 7a is filtered with a high-pass filter and a low-pass filter or a band-pass filter. The lower cutoff frequency fi lies between 5 Hz and 60 Hz, preferably between 10 Hz and 30 Hz, and most preferably at 15 Hz, and the upper cutoff frequency fn lies between 400 Hz and 800 Hz, preferably between 500 Hz and 700 Hz, and most preferably at 600 Hz. After applying the filters, the acceleration signal curve a'(t) shown in Fig. 7b is obtained. By limiting the recorded acceleration signals a to the frequency range between the lower cutoff frequency fi. upper limit frequency fn, a clear amplitude curve is recognizable in the acceleration signal curve a'(t), which also has a first maximum 16 or first minimum 17 at time ti and a second maximum 16' and second minimum 17' at time tz as characteristic features.

[0061] Subsequently, the acceleration signal curve a'(t) is processed by numerical integration, resulting in the acceleration signal curve a"(t) shown in Fig. 7c. This is characterized by a further approximation to the force signal curve F(t). In particular, the amplitude ratios of maximum 16, 16' to minimum 17, 17' of the acceleration signal curve a"(t) already approximately correspond to those of the force signal curve F(t).

Claims

Claims 1. Method for approximating an acceleration signal profile a(t) recorded when a rail-bound vehicle passes over a measuring section (1 , 1', 1") to the characteristic features of a corresponding force signal profile F(t), wherein the measuring section (1 , 1', 1") is designed as a rail (3) and has at least one acceleration sensor (11), whose acceleration signals a are transmitted to an electronic evaluation unit (13) for reception and processing, comprising the following method steps: a) Determining the acceleration signal profile a(t) resulting from the wheel contact force F acting on the measuring section (1 , 1', 1") when passing over it by continuously recording the acceleration a using the at least one acceleration sensor (11), b) Filtering the acceleration signal profile a(t) determined in step a) with a high-pass filter and a low-pass filter or a band-pass filter,and c) Numerical integration of the acceleration signal profile a'(t) obtained by filtering in step b)., 2. Method according to claim 1, characterized by the following further method step: d) Scaling the acceleration profile a"(t) obtained in step c) by numerical integration by multiplication with a factor k.

3. Method according to one of claims 1 or 2, characterized in that in step b) the cutoff frequency fi. of the high-pass filter is between 5 Hz and 60 Hz, preferably between 10 Hz and 30 Hz and most preferably 15 Hz.

4. Method according to one of claims 1 to 3, characterized in that in step b) the cutoff frequency fa of the low-pass filter is between 400 Hz and 800 Hz, preferably between 500 Hz and 700 Hz and most preferably 600 Hz. A method according to any one of claims 1 to 4, characterized in that in step d) the factor k is determined by calibrating the acceleration signal profile a"(t) obtained by numerical integration on the basis of a corresponding force signal profile F(t) acquired by means of the measuring section (1, 1', 1"). A method according to any one of claims 1 to 5, characterized in that in step d) the factor k is determined by calibrating the acceleration signal profile a"(t) obtained by numerical integration on the basis of values ​​and / or profiles of the wheel contact force F stored in the evaluation unit (13). A device for approximating an acceleration signal profile a(t) acquired when a rail-bound vehicle passes over a measuring section (1, 1', 1") to the characteristic features of a corresponding force signal profile F(t), wherein the measuring section (1, 1',The measuring section (1, 1', 1") is configured as a rail (3) and comprises at least one acceleration sensor (11) and an electronic evaluation unit (13), characterized in that the electronic evaluation unit (13) is configured to: a) determine the acceleration signal profile a(t) resulting from the wheel contact force F acting when crossing the measuring section (1, 1', 1") by continuously detecting the acceleration a using the at least one acceleration sensor (11); b) filter the acceleration signal profile a(t) determined under a) using a high-pass filter and a low-pass filter or a band-pass filter; and c) numerically integrate the acceleration signal profile a'(t) obtained under b) by filtering. The device according to claim 7, characterized in that the measuring section (1, 1', 1") additionally comprises at least one force transducer (10) for detecting the wheel contact force F. The device according to claim 8, characterized in that:that the area of ​​the measuring section (1 ', 1 ") with the at least one acceleration sensor (11 ) and the area with the at least one force sensor (10) in the direction of travel x partially, overlap or follow one another. Device according to one of claims 7 to 9, characterized in that the measuring section (1 , 1', 1") has a transverse force sensor (6, 7, 8, 9) or rail switch at least at its beginning and / or end.

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