DEVICE AND METHOD FOR DETERMINING THE OUT-ROUNDNESS OF A WHEEL OF A RAIL-BOUND VEHICLE

Description

[0001] The invention relates to a device for determining the out-of-roundness of a wheel of a rail-bound vehicle according to the preamble of claim 1 or 2 and to a method for determining the out-of-roundness of a wheel of a rail-bound vehicle according to claim 10 or 11.

[0002] 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 wheel on the rail, posing the risk of damage to the rail vehicle and track. The associated safety risks, as well as noise emissions and vibrations of the subsurface, are undesirable.

[0003] To prevent such effects, there has been no lack of effort 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 while the vehicle is stationary, 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.

[0004] 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.

[0005] 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 thus obtained are subjected to an evaluation procedure to determine the extent of wheel damage. Characteristics that provide information about the type and severity of the wheel damage are filtered out of the measurement signal using suitable frequency filter stages and / or an FFT analysis. The disadvantage of this approach is that the measurement result is only approximate.

[0006] 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.

[0007] FR 2 893 900 A1 discloses a method and device for detecting roundness defects on the wheels of rail vehicles. For this purpose, a section of track resting on sleepers is equipped with piezoelectric acceleration sensors that record the amplitude of the track vibrations caused by the wheels as they pass over the track section. The acceleration sensors are arranged between the sleepers of the track section, the length of which is at least equal to the circumference of the wheels. Inductive sensors at the ends of the track section are used for synchronization and to determine the wheel speed. The signals recorded by the acceleration sensors are digitized and filtered in a vibration range with maximum damping. This allows for the detection of defects by comparing them with reference signal profiles, their nature can be further determined, and the wheels affected by the defects can be identified.

[0008] DE 10 2019 114 288 A1 discloses a method and a device for locating a singular defect on the running surface of a wheel of a rail-bound vehicle when traveling over a rail designed as a measuring section in the X direction. A force measuring device continuously measures the contact force F of the wheel over the length L of the measuring section. A distance measuring device measures the lateral distance of the wheel from the rail at at least one defined position within the measuring section. The defect is then detected by evaluating the profile of the wheel contact force F in an electronic evaluation unit. The position of the wheel-rail contact on the running surface of the wheel is determined at the time the defect occurs and based on the measured lateral distance.Based on this prior art, the object of the invention is to provide a device and a method with which the out-of-roundness of a wheel of a rail-bound vehicle can be determined reliably and with high accuracy, taking economic aspects into account.

[0009] This object is achieved by a device having the features of patent claim 1 and alternatively of patent claim 2, as well as by a method having the features of patent claim 10 and alternatively of patent claim 11.

[0010] Advantageous embodiments emerge from the subclaims.

[0011] The invention, like the aforementioned prior art, is based on the fundamental idea of ​​using the measured values ​​of the wheel contact forces obtained when a rail vehicle travels over a measuring section not only to determine the weight of the rail vehicle, but also to evaluate them simultaneously with regard to possible wheel runout. A prerequisite for complete recording of the runout is that the measuring section extends over at least one times the wheel circumference. In order to be able to make statements about the periodicity of the runout or its wavelength and to represent them graphically as part of the evaluation, knowledge of the actual wheel circumference (actual wheel circumference) of a wheel to be tested is essential. It proves problematic that the actual wheel circumference differs from the original wheel circumference (nominal wheel circumference) due to gradual wear.Within the scope of the invention, it is therefore provided to determine the actual wheel circumference when rolling over the measuring section or the time period Δt which corresponds to the rolling of the actual wheel circumference U ist on the measuring section.

[0012] In this context, the invention has recognized that it is sufficient for determining the actual wheel circumference or the time period Δt if characteristic features repeat over the course of the measurement signal, whereby the measurement signal can also originate from sensors other than the force transducers. If a sufficiently high degree of agreement indicates a repetition of the measurement signal curve, it is assumed according to the invention that the section of the measurement signal curve between a characteristic feature and its repetition corresponds to the actual wheel circumference. Depending on the time period Δt between the first detection of a characteristic feature at time t 1 and its repetition at time t 2 in combination with the known driving speed v, the actual wheel circumference U actual can be calculated according to: U ist = v * Δt mit Δ t = t 2 − t 1

[0013] According to the invention, the actual wheel circumference U determined in this way or the time period Δt determined in this way is used as the basis for the evaluation of the force signal curve determined with force transducers, whereby the section of the force signal curve determined for the evaluation corresponds to the length of the actual wheel circumference or the time window Δt.

[0014] A first resulting advantage lies in the possibility of using sensors that require relatively little effort to acquire and / or install. For example, sensors suitable for the invention, such as accelerometers, can be mounted directly on the rails in the area between the sleepers, without affecting the bearings of the rails on the sleepers. The installation of a device according to the invention on a track is therefore possible with relatively little equipment effort and in a short time, resulting in an exceptionally advantageous cost-benefit ratio.

[0015] Because of the minimal intervention in the existing track construction, the devices and methods according to the invention are not only suitable for the construction of new measuring lines, but also excellently suited for retrofitting existing measuring lines, whose functionality is thus extended.

[0016] For the users and operators of the railway routes according to the invention, it is of crucial importance that disruptions to rail traffic, such as the temporary closure of a railway line during the construction or retrofitting of a measuring section according to the invention, are kept to a minimum.

[0017] Since absolute measurement values ​​are not required to determine the actual wheel circumference U actual, but the relative measurement signal curve is sufficient, the requirements for the sensors are less stringent, with the further advantage that calibration intervals for the sensors can be longer. As a result, the devices and methods according to the invention contribute significantly to increasing cost-effectiveness compared to the prior art.

[0018] The length of a measuring section according to the invention is selected such that it can be concluded with sufficient probability from the repetition of significant features in the measurement signal curve that the recurring features are due to the same circumferential section of the wheel. For this purpose, the length of a measuring section according to the invention must be greater than the simple actual wheel circumference U ist . To be on the safe side, it is preferred according to the invention that the length of the measuring section corresponds to at least 1.2 times the nominal wheel circumference U nom . The significance of the measured values ​​can be further increased if the length of the measuring section is selected to be longer. In this sense, a length of the measuring section which corresponds to at least 1.5 times the nominal wheel circumference U nom or even at least twice the nominal wheel circumference U nom is particularly preferred by the invention.

[0019] In an advantageous development of the invention, the correspondence of recurring significant features in the measurement signal curve is determined by autocorrelation, wherein the measurement signal curve is examined for correlations between temporally spaced measurement signal curve sections.

[0020] According to one embodiment of the invention, the force signal curve of the first partial measuring section and the acceleration signal curve of the second partial measuring section are recorded independently of each other. The measurement data from both partial measuring sections are thus directly incorporated into the evaluation, which promotes the accuracy and reliability of the evaluation.

[0021] It is possible for the first and second measuring sections to follow one another in the direction of travel, i.e. to be spatially separated from one another, with the second measuring section following the first or vice versa. The length of the measuring section is therefore calculated by adding the first and second measuring sections, with the force and acceleration signal curves being generated sequentially in time. This has the advantage that the two measuring sections can be constructed independently of one another. Especially when retrofitting existing measuring sections, there is no need to intervene in the existing measuring section, which would otherwise entail the risk that the construction work could potentially impair the existing measuring equipment.In addition, in this embodiment, measurement signals are obtained over a relatively large length, which represents significantly more than twice the wheel circumference and therefore enables the evaluation of the measured values ​​on a broader basis.

[0022] Alternatively, it is possible for the first partial measuring section and the second partial measuring section to partially or completely overlap in the direction of travel. In this embodiment, the force signals and acceleration signals are recorded at least partially simultaneously. Such an embodiment opens up the possibility of designing the measuring section extremely compactly, which is particularly advantageous in confined spaces and thus expands the application range of a device according to the invention to include confined spaces.

[0023] According to another embodiment of the invention, the force signal curve of the first partial measuring section and the acceleration signal curve of a remaining measuring section, which together form the second partial measuring section, are combined. In order to be able to base the evaluation on a consistently uniform signal curve, it is provided to transform the acceleration signal curve into a force signal curve or the force signal curve into an acceleration signal curve. Since the force transducers are functionally part of both the first partial measuring section and the second partial measuring section, they perform a dual function, so that in this embodiment, the effort for the measuring device and its installation can be reduced to an absolute minimum.

[0024] To measure the wheel contact force, load beams, load cells, or weighing discs are preferably used as force transducers. These are arranged beneath the rail, usually in the sleeper or between the rail and the ground. To obtain a force signal that is as uniform as possible over the length of the first partial measuring section, several force transducers are preferably provided, arranged consecutively in the direction of travel, with a mutual spacing preferably between 300 mm and 1000 mm. The same applies to the arrangement of the accelerometers, with the proviso that their maximum spacing is 2000 mm.

[0025] For a measuring section supported on sleepers, the maximum distance between the force transducers and accelerometers is advantageously based on the sleeper spacing, with the maximum distance between the force transducers and / or accelerometers corresponding to twice the sleeper spacing, preferably to one-times the sleeper spacing. These measures facilitate the evaluation of the signal curve and increase the precision of the resulting results. The force transducers are arranged below the rail, preferably between the rail and sleeper or rail and subgrade. The accelerometers are arranged directly on the rail. Accordingly, the advantage of using accelerometers is that no intervention is required in the substructure of the rails or in the track bed. This results in considerable time and cost savings.

[0026] A measuring section according to the invention preferably has at least one transverse force sensor per rail, which is, for example, integrated into the rail and detects the shear stresses induced in the rail by a wheel load. Suitable transverse force sensors include strain gauges or measuring eyes. The transverse force signal generated by a transverse force sensor can be used to precisely determine the point in time at which a wheel rolls over the transverse force sensor. Such a signal can be used, for example, as a trigger for starting and / or stopping a measuring process and / or for axle and vehicle identification.

[0027] By arranging two transverse force transducers at the beginning and end of the first measuring section L1, whose measuring device includes force transducers, these can be used to correct force shunts or prevent force shunts from the adjacent rail. This enables both continuous recording of the signals from the force transducers arranged beneath the rail and precise determination of the wheel contact.

[0028] In addition, using two transverse force transducers arranged at a known distance along the rail, the time of passage from the first transverse force transducer to the second transverse force transducer can be determined based on the times assigned to the two transverse force signals, and the travel speed v of the rail vehicle can be determined. Advantageously, the travel speed v calculated in this way is directly incorporated into the determination of wheel out-of-roundness.

[0029] A preferred embodiment of the invention provides for the provision of several transverse force transducers in each rail within a partial measuring section, arranged consecutively in the direction of travel, which divide the partial measuring section into several sections. This offers, among other advantages, the further advantage that changes in the driving speed v within the measuring section can be recorded and taken into account when determining the actual wheel circumference U actual, thus allowing for greater accuracy in the evaluation of the measurement signals.

[0030] It is further preferred that the transverse force transducers be spaced apart by a distance corresponding to one or two times the sleeper spacing. This embodiment ensures that only one wheel of a rail vehicle is located between two adjacent transverse force transducers of a partial measuring section; a signal measured in this section can therefore be unambiguously assigned to this wheel. This simplifies the evaluation of the measurement signals, which ultimately contributes to the high accuracy and quality of the evaluation results.

[0031] Without being limited thereto, the invention is 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 appropriate, identical reference numerals are used for identical or functionally equivalent features of different embodiments.

[0032] It shows Fig. 1 is a perspective oblique view of a first embodiment of a device according to the invention, Fig. 2 shows the time course of the in the first partial measuring section of the Fig. 1 shown device, Fig. 2b the time course of the force signal recorded in the second partial measuring section of the Fig. 1 shown device, Fig. 3 is a perspective oblique view of a second embodiment of a device according to the invention, Fig. 4 shows the time course of the acceleration signal recorded in the first partial measuring section of the device shown in Fig. 3 shown device, Fig. 4b the time course of the force signal recorded in the second partial measuring section of the Fig. 3 shown device, Fig. 5 a perspective oblique view of a third embodiment of a device according to the invention, Fig. 6a the time course of the acceleration signal recorded in the first partial measuring section of the device shown in Fig. 5 shown device, Fig. 6b the time course of the force signal recorded in the remaining measuring distance of the Fig. 5 acceleration signal recorded by the device shown, and Fig. 6c shows the time course of the Fig. 6a The force signal shown combined with the Fig. 6b represented acceleration signal transformed into a force signal.

[0033] Fig. 1 shows a first embodiment of a device according to the invention with a measuring section 1 for evaluating the wheel contact force F and acceleration a 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 parallel rails 3 that 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 on 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. The direction of travel of the rail-bound vehicle is denoted by x, and the wheel contact force exerted by a wheel 5 on a rail 3 is denoted by F.

[0034] The measuring section 1 comprises a first partial measuring section 1.1 for detecting the wheel contact force F and a second partial measuring section 1.2 for detecting the acceleration a with which the wheels 5 act on the rails 3 while a rail-bound vehicle travels over the measuring section 1. In the present first embodiment of the invention, the two partial measuring sections 1.1 and 1.2 follow one another in the direction of travel x, with the second partial measuring section 1.2 seamlessly connecting to the first partial measuring section 1.1 in the direction of travel x. A reverse order and / or a spatial distance between the two partial measuring sections 1.1 and 1.2 are also within the scope of the invention.

[0035] The first partial measuring section 1.1 extends over a length L1 that corresponds at least to the nominal wheel circumference U nom 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.

[0036] In the area of ​​the first partial measuring section 1.1, a first measuring device for detecting the wheel contact force F exerted by a wheel 5 on the rail 3 is integrated into the rail track 2. The first measuring device comprises two transverse force transducers 6, 7 arranged on the rail 3, one of which is installed at the beginning and the other at the end of the first partial measuring section 1.1. These transducers are, 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.

[0037] The transverse force transducers 6, 7 serve, on the one hand, to correct force shunts to compensate for interference from adjacent rail sections. On the other hand, the transverse force transducers 6, 7 can be used as switches for the start and end of the measurement process of the first measuring device and / or for axle detection and vehicle identification.

[0038] Preferably, the driving speed v in the area of ​​the first partial measuring section 1.1 is 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 t 0 and t X (see Fig. 2a ).

[0039] Additionally, force transducers 8 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 measuring section 1, preferably several successive force transducers 8 are provided in the direction of travel x, the mutual spacing of which corresponds to a maximum of twice the sleeper spacing, preferably to one sleeper spacing. In the present embodiment, each of the two rails 3 rests on force transducers 8, which in turn are mounted on successive sleepers 4.

[0040] The second partial measuring section 1.2 has a length L2 that is greater than the length L1 and corresponds to at least 1.2 times the nominal wheel circumference U nom 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 L2 of at least 4710 mm, preferably at least 5888 mm, most preferably 7850 mm.

[0041] In the area of ​​the second partial measuring section 1.2, the device according to the invention has a second measuring device for detecting the acceleration a exerted by a wheel 5 on the rail 3, which is also integrated into the rail track 2. The second measuring device also comprises transverse force transducers 9, 10 installed at the beginning and end of the rail 3, whereby in the present first embodiment, the first transverse force transducer 9 in the direction of travel x corresponds to the second transverse force transducer 7 of the first partial measuring section 1.1, thus performing a dual function. In their actual design and function, the transverse force transducers 9, 10 correspond to those of the first partial measuring section 1.1, so that the explanations there apply accordingly, in particular with regard to the possibility of force shunt correction and determination of the travel speed v in the area of ​​the second partial measuring section 1.2.

[0042] In addition, accelerometers 11 are provided in the area of ​​the second partial measuring section 1.2 to measure the acceleration a. The accelerometers 11 are each mounted between two sleepers 4 on the underside of the rails 3, resulting in a mutual spacing of the accelerometers 11 in the direction of travel x that corresponds to one sleeper spacing, but can also be twice the sleeper spacing. The accelerometers 11 measure the acceleration value or the acceleration signal of the rail at the location where the sensor is located.

[0043] The lateral force sensors 6, 7, 9, 10, the force sensor 8 for the wheel contact force F, and the acceleration sensor 11 are connected via data lines 12 to an electronic evaluation unit 13, where data storage and processing takes place. The data from a measurement process is transmitted to a higher-level central location via radio or another data line 14.

[0044] Fig. 2a shows the time course of the force signal F measured by force transducers 8 during the travel over the partial measuring section 1.1. The measuring process carried out by the first measuring device begins at time t 0 , defined by the wheel 5 rolling over the lateral force transducer 6, and ends at time t X , at which the wheel 5 rolls over the lateral force transducer 7 and thus leaves the area of ​​the first partial measuring section 1.1. The time period T between times t 0 and t X thus corresponds to the duration of the travel over the first partial measuring section 1.1, the length L 1 of which corresponds at least to the simple nominal wheel circumference U nom and is therefore greater than the actual wheel circumference U . If the spatial distance between the transverse force transducers 6, 7 is known, which in the present embodiment corresponds to the length L1 of the first partial measuring section 1.1, the driving speed v of the rail vehicle in the first partial measuring section 1.1 can be calculated according to the relationship: v = L 1 / T mit T = t X − t 0

[0045] Depending on the quality of the running surface of wheel 5, the amplitude of the force signal F fluctuates more or less strongly around a value corresponding to the static load component F stat . 15 denotes a force maximum or minimum that deviates significantly from the fluctuation range, which, due to its gradient and height, indicates an out-of-roundness of the running surface of wheel 5.

[0046] In Fig. 2b , the time course of the acceleration signal a measured by the acceleration sensors 11 during the travel over the second partial measuring section 1.2 is shown. The rolling over of the lateral force sensor 9 by the wheel 5 corresponds to the time t 0 , at which the measuring process by the second measuring device in the area of ​​the second partial measuring section 1.2 begins. The rolling over of the lateral force sensor 10 by the same wheel 5 defines the time t X , which simultaneously represents the end of the measuring process. The time period T lying between the times t 0 and t X corresponds to the duration of the travel over the second partial measuring section 1.2, the length L2 of which is greater than the length L1 of the first partial measuring section and, in the present case, corresponds to twice the nominal wheel circumference U nom . With a known spatial distance between the lateral force sensors 9, 10, which in the present embodiment corresponds to the length L2 of the second partial measuring section 1.2, the driving speed v of the rail vehicle in the second partial measuring section 1.2 results as above.

[0047] The amplitude of the acceleration signal a fluctuates more or less strongly around the value zero depending on the quality of the running surface of the wheel 5. With the force maximum or force minimum 15 of the force signal curve F(t) ( Fig. 2a ) corresponds to an acceleration maximum 16 in the acceleration signal curve a(t) that deviates significantly from the fluctuation range and is due to the same out-of-roundness on the running surface of the wheel 5. The time of the first occurrence of the acceleration maximum 16 is in Fig. 2b denoted by t 1 . Due to the specified length L2 of the second partial measuring section 1.2, the wheel 5 rolls a second time on the second partial measuring section 1.2 with part of its circumference during the measurement process, or with a corresponding length of L2 with the entire circumference. As the wheel 5 rolls again on the rail 3, an acceleration signal curve a(t) is generated from this point in time, the characteristic features of which correspond to those of the previous acceleration signal curve a(t). The most striking repetition is the acceleration maximum or minimum 16' at time t 2 . The time period Δt between times t 1 and t 2 corresponds to the time it takes the wheel 5 to roll once over its actual circumference U actual . In conjunction with the known driving speed v, the actual circumference U actual of the wheel 5 can be determined according to the relationship: U ist = v * Δt mit Δ t = t 2 − t 1

[0048] For the evaluation of the force signal curve F(t) related to the actual circumference U ist, for example when displaying the wheel runout in polar diagrams or determining their periodicity or wavelength, the time period Δt determined in the second partial measuring section 1.2 or the corresponding actual wheel circumference U ist is transferred to the force signal curve F(t) recorded by means of the first partial measuring section 1.1, which is indicated by arrow 17. The part of the force signal curve F(t) lying within the time period Δt or actual circumference U ist is then used as the basis for further evaluation to determine the runout of the wheel 5.

[0049] A further, second embodiment of the invention is described below with reference to Fig. 3, 4a und 4b explained. The Fig. 3 The measuring section 1' shown also comprises a first partial measuring section 1.1', which largely corresponds to the first partial measuring section 1.1 of the first embodiment, and a second partial measuring section 1.2', which largely corresponds to the second partial measuring section 1.2 of the first embodiment. To avoid repetition, with regard to the rail track 2, the two measuring devices, the transverse force transducers 6, 7, 9, 10, force transducers 8, acceleration transducers 11, data lines 12, evaluation unit 13, etc., reference is made to the explanations made there, which apply accordingly.

[0050] Differences to the first embodiment described above result from the number of transverse force sensors in the area of ​​the first partial measuring section 1.1', where in the second embodiment according to Fig. 3 between the end shear force transducers 6, 7 additional shear force transducers 18 are arranged at twice the sleeper spacing.

[0051] A further difference lies in the relative arrangement of the first partial measuring section 1.1' and the second partial measuring section 1.2' to each other. While in the first embodiment according to Fig. 1 The two partial measuring sections 1.1 and 1.2 follow one another in the direction of travel x, overlap at the Fig. 3 In the embodiment shown, the first partial measuring section 1.1' and the second partial measuring section 1.2' have a common beginning, which is defined by the shear force transducer 6 and 9, respectively. The first partial measuring section 1.1' ends after the length L1 with the shear force transducer 7, while the second partial measuring section 1.2' continues to the shear force transducer 10, which defines the end of the second partial measuring section 1.2'.

[0052] As can be seen from the Fig. 4a und 4b As can be seen, at time t 0 both the recording of the wheel contact force F by means of the force transducers 8 and the recording of the acceleration a by means of the acceleration transducers 11 begin simultaneously. Accordingly, the force signal curve F(t) over the length L1 is recorded at the same time as the acceleration signal curve a(t).

[0053] The evaluation of the force signal curve F(t) and the acceleration signal curve a(t) is carried out analogously to the first embodiment described above. A repetition of the acceleration signal curve a(t) is determined based on characteristic features in the acceleration signal curve a(t), such as acceleration maxima or minima 16, 16', and a time period Δt is assigned to the preceding acceleration signal curve a(t) until the repetition. Given a known driving speed v, the actual circumference U actual of wheel 5 can be determined from this.

[0054] Using the time period Δt or the actual wheel circumference U ist thus determined, a section of the force signal curve F(t) is then selected, analogously to the procedure in the first embodiment of the invention, which section corresponds exactly to the actual wheel circumference U ist and which forms the basis for polar diagrams, statements on periodicity, wavelength and the like.

[0055] Subject of the Fig. 5, 6a, 6b und 6c is a third embodiment of the invention, in which the measuring section 1" in turn comprises a first partial measuring section 1.1" for determining the wheel contact force F over the length L1. The partial measuring section 1.1" with the associated first measuring device corresponds to the Fig. 1, 2a und 2b described first partial measuring section 1.1, so that in order to avoid repetition, reference is made to the explanations there.

[0056] Differences arise in the area of ​​the second partial measuring section 1.2", which in the third embodiment is composed of the first partial measuring section 1.1" of length L1 and a remaining measuring section 1.3 of length L3, which together result in the length L2 of the second partial measuring section 1.2".

[0057] The remaining measuring section 1.3 is analogous to the second partial measuring section 1.2 of the Fig. 1, 2a und 2b described embodiment, with transverse force transducers 7, 10 at the beginning and end of the remaining measuring section 1.3 and acceleration transducers 11 arranged between the sleepers 4. In comparison with the length L1 of the first partial measuring section 1.1" and the length L2 of the second partial measuring section 1.2", the remaining measuring section 1.3 is characterized by a shorter length L3.

[0058] When a rail vehicle passes over the measuring section 1", a force signal curve F(t) corresponding to Fig. 6a When the end of the first partial measuring section 1.1" is reached and the remaining measuring section 1.3 begins at time t X, the acquisition of the acceleration signal over the length L3 of the remaining measuring section 1.3 begins, which corresponds to the Fig. 6b shown acceleration curve a(t) with the acceleration maxima and acceleration minima 16.

[0059] For further evaluation, the acceleration signal curve a(t) is transformed into a calculated force signal curve F'(t), which is combined with the force signal curve F(t) determined in the first partial measuring section 1.1". The result after transformation and addition corresponds to the force signal curve F(t) and F'(t) as in Fig. 6c which extends over the entire length L2 of the second partial measuring section 1.2". One can see the force maxima 15, 15' at time t 1 and time t 2 , which are each due to the same out-of-roundness of the wheel 5 and thus mark the beginning and end of the actual wheel circumference U as well as the time period Δt.

[0060] The actual wheel circumference U determined in this way or the time period Δt determined in this way is entered into the force signal curve F(t) as indicated by arrow 17 according to Fig. 6a and defines there a section of the force signal curve F(t) which corresponds exactly to the actual circumference U of the wheel 5 and which, as in the previously described embodiments of the invention, forms the basis for further evaluation.

[0061] The device and method according to the invention pursue the overall approach of designing the measuring sections as short as possible, with as little interference with the track bed or subsurface as possible, and thus as cost-effectively as possible. Through the arrangement of the measuring sections and the combination of the various sensors, namely force transducers under the rail (vertical forces, wheel contact forces), transverse force transducers in the rail, and acceleration transducers, the wheel contact forces and wheel out-of-roundness are nevertheless determined extremely accurately and reliably. The findings obtained on a partial measuring section, which is minimally required for a full wheel circumference, are verified using a second partial measuring section and alternative sensors.

Claims

1. An apparatus for ascertaining out-of-roundnesses of a wheel (5) of a railbound vehicle when passing over a rail (3) designed as a measuring section (1, 1') in the direction of travel x at the travel velocity v, comprising - a first measuring subsection (1 .1, 1.1'), which extends over a length L1, and includes a first measuring device having force transducers (8) for detecting the contact force F of the wheel (5) over the length L1, and comprising a second measuring subsection (1.2, 1.2') , which extends over a length L2 and includes a second measuring device for ascertaining the actual circumference Uist of the wheel (5), - the length L1 of the first measuring subsection (1 .1, 1.1') corresponding at least to the nominal circumference Unom of the wheel (5); and comprising - an electronic evaluation unit (13) for receiving and processing the measured values detected with the aid of the first measuring device and the second measuring device; - the length L2 of the second measuring subsection (1.2, 1.2') being greater than the length L1 of the first measuring subsection (1.1, 1.1'); and - the second measuring device being formed from - - acceleration transducers (11) for detecting the acceleration a applied by the wheel (5) to the rail (3) over the length L2 of the second measuring subsection (1.2, 1.2'); and - the evaluation unit (13) being designed to generate a continuous force signal form F(t) from the measured values of the first measuring device over the length L1; and to generate - a further signal form from the measured values of the second measuring device over the length L2, from which, based on the travel velocity v, the actual circumference Uist of the wheel (5) or the time period Δt corresponding to the rolling of the actual wheel circumference Uist on the second measuring subsection (1.2, 1.2') may be derived; - the ascertainment of the out-of-roundnesses of the wheel (5) being based on a segment of the force signal form F(t), which corresponds to the actual circumference Uist or the time period Δt.

2. An apparatus for ascertaining out-of-roundnesses of a wheel (5) of a railbound vehicle when passing over a rail (3) designed as a measuring section (1") in the direction of travel x at the travel velocity v, comprising - a first measuring subsection (1.1"), which extends over a length L1, and includes a first measuring device having force transducers (8) for detecting the contact force F of the wheel (5) over the length L1, and comprising a second measuring subsection (1.2") , which extends over a length L2 and includes a second measuring device for ascertaining the actual circumference Uist of the wheel (5), - the length L1 of the first measuring subsection (1.1‴) corresponding at least to the nominal circumference Unom of the wheel (5); and - an electronic evaluation unit (13) for receiving and processing the measured values detected with the aid of the first measuring device and the second measuring device; - the length L2 of the second measuring subsection (1.2") being greater than the length L1 of the first measuring subsection (1.1") by the length L3 of a remaining measuring section (1.3); - the first measuring subsection (1.1") completely overlapping the second measuring subsection (1.2"); and - the second measuring device being formed from - - force transducers (8) for detecting the contact force F over a first partial length of the second measuring subsection (1.2"), which corresponds to the first measuring subsection (1.1"); and - - acceleration transducers (11) for detecting the acceleration a applied by the wheel (5) to the rail (3) over a second partial length of the second measuring subsection (1.2"), which corresponds to the remaining measuring section (1.3), the first partial length and the second partial length together resulting in the length L2 of the second measuring subsection (1.2"); and - the evaluation unit (13) being designed to generate a force signal form (F(t) from the measured values of the first measuring device over the length L1 and a further signal form from the measured values of the second measuring device over the length L2, from which, based on the travel velocity v, the actual circumference Uist of the wheel (5) or the time period Δt corresponding to the rolling of the actual wheel circumference Uist on the second measuring subsection (1.2") may be derived; - the ascertainment of the out-of-roundnesses of the wheel (5) being based on a segment of the force signal form F(t), which corresponds to the actual circumference Uist or the time period Δt.

3. The apparatus according to Claim 1 or 2, characterized in that the length of the first measuring section (1, 1', 1") formed by the first measuring subsection (1.1, 1.1', 1.1") and the second measuring subsection (1.2, 1.2', 1.2") corresponds at least to 1, 2 times the nominal circumference Unom of the wheel (5), preferably at least 1.5 times the nominal circumference Unom, most preferably at least 2 times the nominal circumference Unom.

4. The apparatus according to Claim 1 or 3, characterized in that the first measuring subsection (1.1) and the second measuring subsection (1.2) follow each other in the x direction.

5. The apparatus according to one of Claims 1 through 3, characterized in that the first measuring subsection (1.1', 1.1") completely or partially overlaps the second measuring subsection (1.2, 1.2') in the direction of travel x.

6. The apparatus according to one of Claims 1 through 5, characterized in that the spacing of adjacent force transducers (8) of the first measuring subsection (1.1, 1.1', 1.1") is between 300 mm and 1,000 mm.

7. The apparatus according to one of Claims 1 through 6, characterized in that the spacing of adjacent acceleration transducers (11) of the second measuring subsection (1.2, 1.2', 1.2") is between 300 mm and 2,000 mm.

8. The apparatus according to one of Claims 1 through 7, characterized in that the rail (3) forming the measuring section (1, 1', 1") is supported on ties (4), and the spacing of the force transducers (8) and / or acceleration transducers (11) corresponds to the spacing of the ties (4) in the x direction.

9. The apparatus according to one of Claims 1 through 8, characterized in that a transverse force transducer (6, 7, 9, 10) or track switch is arranged in each case at the beginning or end of the first measuring subsection (1.1, 1.1', 1.1") and / or second measuring subsection (1.2, 1.2', 1.2").

10. A method for ascertaining out-of-roundnesses of a wheel (5) of a railbound vehicle when passing over a rail (3) designed as a measuring section (1, 1') in the direction of travel x at the travel velocity v, comprising the following steps: a) Continuously detecting the contact force F applied by the wheel (5) to the rail (3) over the length L1 of a first measuring subsection (1.1, 1.1'), which corresponds at least to the nominal circumference Unom of the wheel; b) Continuously detecting the acceleration a applied by the wheel (5) to the rail (3) over the length L2 of a second measuring subsection (1.2, 1.2'), the length L2 being greater than the length L1; c) Ascertaining the actual circumference Uist of the wheel (5) or the time period Δt corresponding to the rolling of the actual circumference Uist on the second measuring subsection (1.2, 1.2'), based on the travel velocity v, by evaluating the signal form detected under step b); d) Ascertaining out-of-roundnesses of the wheel (5) by evaluating the force signal form detected under step a) over the length of the actual circumference Uist or the time period Δt ascertained under step c).

11. The method for ascertaining out-of-roundnesses of a wheel (5) of a railbound vehicle when passing over a rail (3) designed as a measuring section (1") in the direction of travel x at the travel velocity v, the measuring section (1") being made up of a first measuring subsection (1.1") of the length L1 and a second measuring subsection (1.2") of the length L2, which overlap each other in the direction of travel x, the length L2 of the second measuring subsection (1.2") being greater than the length L1 of the first measuring subsection (1.2") by the length L3 of a remaining measuring section (1.3), comprising the following steps: a) Continuously detecting the contact force F applied by the wheel (5) to the rail (3) over length L1 of the first measuring subsection (1.1"), which corresponds at least to the nominal circumference Unom of the wheel, the first measuring subsection (1.1") corresponding to a first partial length of the second measuring subsection (1.2"); b) Continuously detecting the acceleration a applied by the wheel (5) to the rail (3) over a second partial length of the second measuring subsection (1.2"), which corresponds to the remaining measuring section (1.3), the first partial length and the second partial length together resulting in the length L2 of the second measuring subsection (1.2"); and c) Transforming the form of the acceleration a detected continuously over the second partial length of the measuring subsection (1.2") in step b) into a force signal form, and combining the force signal form obtained thereby with the form of contact force F detected continuously over the first partial length of the second measuring subsection (1.2") in step a);. d) Ascertaining the actual circumference Uist of the wheel (5) or the time period Δt corresponding to the rolling of the actual wheel circumference Uist on the second measuring subsection (1.2"), based on the travel velocity v, by evaluating the signal form detected under step c); e) Ascertaining out-of-roundnesses of the wheel (5) by evaluating the force signal form detected under step a) over the length of the actual circumference Uist or the time period Δt ascertained under step d).

12. The method according to Claim 10, characterized in that steps a) and b) follow each other over time.

13. The method according to Claim 10 or 11, characterized in that steps a) and b) are carried out completely or partially in parallel over time.

14. The method according to one of Claims 10 through 13, characterized in that the evaluation of the signal form detected in step b) for ascertaining the actual circumference Uist of the wheel (5) or the time period Δt according to step c) takes place by means of autocorrelation.