VEHICLE COMPLETING AT LEAST ONE VEHICLE WHEEL WITH A VEHICLE PNEUMATIC TIRE ENCLUDING A TIRE INSIDE AND ONE, TWO OR AT LEAST THREE SOUND WAVE RECEIVERS FOR REPEATED OR CONTINUOUS DETECTION OF AIRBORNE SOUND WAVE SIGNALS AND A CORRESPONDING METHOD

Description

[0001] The invention relates to a vehicle comprising at least one vehicle wheel with a pneumatic vehicle tire comprising a tire interior.

[0002] The invention also relates to a method for the multiple or continuous detection of airborne sound wave signals from a pneumatic vehicle tire of a vehicle wheel of a vehicle.

[0003] The use of tire repair kits to seal leaks in tires is well known in the art. The most common application of these repair kits is to inflate and seal the leaking tire after the vehicle has been stopped due to a warning signal about a decrease in tire pressure. In this case, a corresponding warning signal is often given to the driver as soon as the tire pressure falls below a certain threshold. Further information about the leak on the leaking tire cannot be recorded. However, depending on the type of leak on the tire, different applications could be used to seal it or to call for help. For this purpose, it would be helpful if more information about the leak that has occurred or is occurring were available.

[0004] Various devices are known in the prior art: EP 0060469 A1 discloses a non-destructive tire testing apparatus with an acoustic ultrasonic wave transmitter and an acoustic ultrasonic wave receiver, which are arranged on the opposite side of a tire wall (cf. claim 1).

[0005] EP 0392859 A2 discloses a non-destructive testing method with an acoustic ultrasonic wave transmitter and an acoustic ultrasonic wave receiver, which are arranged on the opposite side of a tire wall (cf. claim 1).

[0006] GB 571817 A discloses a device for detecting defects in the material of articles, the device comprising means for generating variable high frequency sound waves and means for directing the sound waves onto the surface of the article and means for detecting sound waves on the opposite side of said surface of the article (see lines 11 to 20, on page 1).

[0007] JP H0244247 A discloses an ultrasonic measuring unit comprising a resin wedge (see abstract).

[0008] US 4327579 A discloses an ultrasonic vehicle testing device comprising an array of ultrasonic transmitting transducers and an array of ultrasonic receiving transducers (see claim 1). A vehicle with a tire noise measurement system is known from CN 107796639 A. US 4491013 A discloses a tire test bench with an ultrasonic sensor for tire paint detection.

[0009] This object is achieved according to the invention by a vehicle according to claim 1.

[0010] It is a major achievement of the present invention to have discovered that the leakage of a pneumatic vehicle tire of a vehicle can be detected while the vehicle is traveling using a device according to the invention, wherein the sound wave receiver of the device according to the invention is mounted outside the tire interior and directed toward the outer tire surface of the vehicle tire. This special sound wave receiver arrangement outside the tire interior not only allows a leak to be detected as it occurs while traveling, i.e., before the tire pressure drop in the tire falls below a threshold, but also allows qualitative information about the leak that has occurred or is about to occur to be recorded.

[0011] The documents described above and known from the prior art, however, only feature sound wave receivers located inside the tire cavity, with which the corresponding detection of a leak in a pneumatic vehicle tire on a vehicle during operation can only be measured under very specific conditions. According to current knowledge, the detection of a leak in a pneumatic vehicle tire using a sound receiver located outside the tire cavity has not yet been achieved.

[0012] Mounting the sound wave receiver outside the interior of the pneumatic vehicle tire not only enables trouble-free detection while driving a vehicle according to the invention, but also sufficiently accurate detection that qualitative information about the leak can be acquired. This special arrangement with the sound receiver outside the interior of the tire thus overcomes a technical prejudice from the prior art and thus represents a special achievement of the present invention.

[0013] A further advantage of the present invention over the prior art is that, using a device according to the invention in a vehicle as described above, a leak in a pneumatic vehicle tire can be detected non-invasively. This means, for example, that a leak in the pneumatic vehicle tire can be detected without filling the interior of the pneumatic vehicle tire with a liquid or without immersing the pneumatic vehicle tire in a liquid. Only this enables detection during driving depending on the location of the leak.

[0014] The airborne sound waves resulting from a leak in a pneumatic vehicle tire are detected sufficiently well, in particular, by sound wave receivers which are aligned in the direction of the tread of the pneumatic vehicle tire, in the direction of the inside sidewall of the pneumatic vehicle tire as seen from the vehicle, or in the direction of the inside outside sidewall of the pneumatic vehicle tire as seen from the vehicle.

[0015] As an example of a sound wave receiver for a device according to the invention, conventional sound transducers such as microphones capable of picking up sound waves with a frequency of 4 Hz to 100 kHz are suitable. A suitable example of such a microphone would be the product from "PCB piezotronics" with the product number "378C01."

[0016] In the context of the present invention, the term "sound" refers in particular to airborne sound. In the context of the present invention, the term "ultrasound" refers to sound waves with a frequency of 1 kHz to 1 GHz. Sound waves with a frequency above 1 GHz are referred to as "hypersonic" in the context of the present invention.

[0017] A vehicle according to the invention is preferably as described above or as described above as preferred, wherein the filter unit is a high-pass filter, or is a band-pass filter and the band-pass filter is designed to filter out signal components of an airborne sound wave signal with frequencies below 35 kHz and above 45 kHz, preferably signal components of an airborne sound wave signal with frequencies below 38 kHz and above 42 kHz.

[0018] A filter unit of a vehicle according to the invention as described above can also be implemented electronically by means of a control unit as described below.

[0019] A vehicle according to the invention as described above or as described above as preferred is particularly preferred, wherein the vehicle comprises at least one filter unit configured to filter out signal components of an airborne sound wave signal with frequencies below 28 kHz and above 36 kHz, wherein the one or at least one filter unit is a bandpass filter. The advantage is that a particularly good signal-to-noise ratio (SNR) is achieved in this signal range.

[0020] An advantage of the above-described aspect of the present invention is that, in particular by filtering out background noise with frequencies outside the above-described ranges, the sound waves generated by a leak can be detected quickly and easily. This rapid detection of the leak makes it possible to identify leaks as they occur while the vehicle is driving. This represents a particular achievement of the present invention compared to detection methods from the prior art. In particular, a person skilled in the art would not have expected that such reliable detection while a vehicle is driving would have been possible by mounting the sound wave receiver outside the interior of the pneumatic vehicle tire and filtering out the above-described frequency ranges from the sound wave signals.This is demonstrated in particular by the improvement in the signal-to-noise ratio according to the experiments described below. In particular, the signal-to-noise ratios thus achieved even allowed qualitative information about the shape and geometry of the leak to be obtained based on the signal height and width.

[0021] Signals that are particularly strong indicate, for example, that the crack in the tire extends along the circumferential direction of the pneumatic vehicle tire, which in particular also makes it possible to determine the length of the crack. Thus, a control unit described below can immediately determine whether the leak can be sealed using a tire repair kit or whether an emergency signal should be sent directly to a towing service or a similar provider. This would be of great help to the unsettled driver in an unfamiliar breakdown situation. However, it is particularly preferred to use various high-pass filters and band-pass filters in a filter unit according to the invention and thus also to be able to precisely determine the frequency of the sound wave signal triggered by the leak in order to advantageously obtain further geometric information about the leak from the frequencies thus detected.

[0022] Since the frequency also depends on the internal pressure of the tire, one can also indirectly conclude about the internal pressure of the tire.

[0023] A vehicle according to the invention is preferably as described above or as described above as preferred, wherein the vehicle comprises a control unit which is designed to two or more than two airborne sound wave signals detected by one or more of the sound wave receivers or two or more than two airborne sound wave signals filtered by one of the filter units to compare, where the airborne sound wave signals originate from the same leakage.

[0024] An advantage of the above-described aspect of the present invention is that by repeatedly recording the sound wave signal originating from the leak, not only information about the geometry or the size of the leak can be acquired in the respectively recorded sound wave signal, but also, in particular, changes in the size and geometry due to the change in the sound wave signal per tire revolution can be detected.

[0025] A vehicle according to the invention is preferably as described above or as described above as preferred, wherein the vehicle wheel of the vehicle or the vehicle pneumatic tire of the vehicle wheel of the vehicle comprises a pressure sensor for measuring the tire internal pressure and the pressure sensor is connected to a or the control unit, wherein the control unit determines a quantitative statement about the size and / or shape of the leakage as a function of the pressure drop per unit of time and as a function of the amplitude of the detected or filtered airborne sound wave signals in this unit of time.

[0026] An advantage of the above-described aspect of the present invention is that by evaluating the pressure sensor signals and the amplitude of the airborne sound wave signals, even more reliable information about the shape or geometry of the leak in the deflated tire can be obtained. This allows the control unit to determine even more reliably whether an emergency call or the use of a tire repair kit should be initiated.

[0027] A vehicle according to the invention is preferably as described above or as described above as preferred, wherein the vehicle wheel of the vehicle or the pneumatic vehicle tire of the vehicle wheel of the vehicle comprises a tire repair kit for sealing a leaky pneumatic vehicle tire and the tire repair kit is connected to a or the control unit, wherein the control unit is configured to activate the tire repair kit for sealing the leak in the pneumatic vehicle tire as a function of the pressure drop per unit of time and / or as a function of the amplitude of the filtered signal in this unit of time, wherein the tire repair kit is preferably designed to be used both during driving operation and outside of driving operation for sealing or inflating pneumatic vehicle tires.

[0028] An advantage of the above-described aspect of the present invention is that, by means of a device according to the invention in a vehicle according to the invention as described above, leaks can be detected so early that the resulting leak can be repaired while driving using an integrated tire repair kit as described above. Thus, the driver advantageously no longer has to stop, but only slows down, to repair the vehicle's pneumatic tire. This represents a particular advantage of the present invention.

[0029] A vehicle according to the invention is particularly preferred as described above or as described above as preferred, wherein two or three sound wave receivers are mounted on the vehicle and provided for this purpose such that one sound wave receiver can measure sound waves of a leak in the tread of the vehicle pneumatic tire and the second sound wave receiver can measure sound waves of a leak in the outer sidewall of the vehicle pneumatic tire as seen from the vehicle and optionally the third sound wave receiver can measure sound waves of a leak in the inner sidewall of the vehicle pneumatic tire as seen from the vehicle.

[0030] An advantage of the above-described aspect of the present invention is that, by means of the various acoustic wave receivers described above, leakage in the tread and in the sidewalls of a pneumatic vehicle tire can be reliably detected during driving.

[0031] A vehicle according to the invention is preferably as described above or as described above as preferred, wherein the one sound wave receiver or one of the sound wave receivers or all of the sound wave receivers comprises an acoustic lens for amplifying the airborne sound wave signals to be detected and the acoustic lens is directed onto an outer wall of the pneumatic vehicle tire of the vehicle wheel of the vehicle.

[0032] An advantage of the above-described aspect of the present invention is that the signal-to-noise ratio can be further improved by using an acoustic lens as described above.

[0033] The advantageous aspects of a vehicle according to the invention described above also apply to all aspects of a method described below, and the advantageous aspects of methods according to the invention discussed below apply accordingly to all aspects of a vehicle according to the invention.

[0034] The invention also relates to a method as defined in claim 7.

[0035] An advantage of the method described above is that several locations on the vehicle pneumatic tire can be monitored simultaneously and that, in particular, changes in a leak, whether it be an increase in the leak or a decrease in the size of the leak during sealing, can be detected.

[0036] In the context of the present invention, the term "time-shifted signals" refers to at least two signals which were recorded at different times but at the same location.

[0037] In the context of the present invention, the term "spatially offset signals" refers to at least two signals which in different places and at the same time or at different times were recorded.

[0038] A method according to the invention as described above or as described above as preferred is preferred, wherein the technical rubber article and the sound wave receiver are moved relative to one another at least during step C), preferably during the entire method, wherein preferably the technical rubber article is rotated relative to the sound wave receiver and the technical rubber article is particularly preferably a pneumatic vehicle tire.

[0039] An advantage of the above-described aspect of the present invention is that the relative movement allows leakage to be detected at different locations on the technical rubber article.

[0040] The filtering out by means of the said filter unit can also be carried out by means of a control unit, also called a processing unit, described above or below.

[0041] An advantage of the above-described aspect of the present invention is that particularly good signal-to-noise ratios are achieved in this way as described above, as is also set out below in the experimental data.

[0042] A method according to the invention as described above or as described above as preferred is preferred, wherein the leakage caused in step B) has a diameter in the range from 1 µm to 50 mm, preferably 0.1 mm to 20 mm. An advantage of the above-described aspect of the present invention is that even such small leaks as described above can be detected using a method according to the invention, since, as demonstrated in the experimental data described below, the signal-to-noise ratio could be significantly improved within the scope of the present invention. Character description:

[0043] It shows: Figure 1A: Graphic representation of the measurement results of an air pressure measurement in the tire interior of a tire (Z-axis) during the rotation of the tire with three leaks and with a sealant in the tire interior of the tire; Figure 1B: Graphic representation of the measurement results of the intensity of the sound waves recorded by the microphone both during phase A and during phase B according to Figure 1A shown; Figure 1C: Graphical representation of the measurement results of the intensity of the sound waves recorded by the microphone during phase A according to Figure 1A ; Figure 1D: Graphical representation of the measurement results filtered by means of a bandpass filter, which exclusively shows the intensity of the sound waves recorded by the microphone during phase A of the experiment, whereby the measurement data shown only show the sound wave signals from the Figure 1C , which are in a frequency range of 35 to 45 kHz.

[0044] Figure 1Ashows a graph in which the measurement results of an air pressure measurement in the tire cavity of a tire (Z-axis) during the rotation of the tire with three leaks and with a sealant in the tire cavity of the tire. In Figure 1A The graph is divided into a phase A and a region B by three vertical dashed lines. At time t = 0, three leaks are punctured into the rotating tire with the sealant contained in its interior. Subsequently, a drop in the air pressure in the tire interior can be observed, as shown in phase A between the first two vertical lines in Figure 1Acan be seen. Subsequently, an increase in the air pressure inside the tire is observed in Phase B. Throughout the entire experiment, particularly during Phase A and Phase B, as well as before and after the three leaks in the vehicle's pneumatic tire were punctured, air was pressed into the tire's interior using a compressor. At the same time, throughout the entire experiment, the sound waves coming from the tire with the three leaks were recorded using a microphone aimed at the tire with the three leaks. The pressure increase in Phase B is due to the sealing of the three leaks using the sealant contained in the tire.

[0045] Figure 1B shows the intensity of the sound waves recorded by the microphone during the experiment, both during phase A and phase B. The Figure 1BThe sound wave signal shown includes sound wave signals with a frequency of 4 kHz to 100 kHz.

[0046] Figure 1C shows only the intensity of the sound waves recorded by the microphone during phase A of the experiment. This would also be reflected in the intermediate figure 1B and Figure 1C shown dashed lines. The Figure 1C The sound wave signal shown includes sound wave signals with a frequency of 4 kHz to 100 kHz. In addition, vertical lines on the horizontal time axis of the Figure 1C The graph shown shows the time of a complete rotation of the rotating tire from which the sound wave signals were recorded. The latter were recorded for experimental purposes using a laser and a corresponding laser barrier. From these displayed times, it can be seen that the tire's rotation accelerated during the experiment.

[0047] Figure 1D shows only the intensity of the sound waves recorded by the microphone during phase A of the experiment. Figure 1D The sound wave signal shown includes only the sound wave signals from the Figure 1C , which are in a frequency range of 35 to 45 kHz. It is clearly visible that the signal-to-noise ratio has improved surprisingly significantly and, in particular, three large peaks per revolution of the rotating tire can be detected, with the signal of the first and third leakage already during the second revolution (see dashed lines in Figure 1Dis greatly reduced. This indicates that the first and third leaks have already been sealed. The second leak can be seen up to the 23rd revolution and therefore decreases more slowly. However, it is clearly visible that not only the number of leaks could be detected using the method shown, but also how differently the different leaks on a tire decrease. Thus, using this method, a seal can be achieved during the

[0048] Driving can be observed and it can be reliably detected whether the driver can continue driving due to the successfully sealed leak or whether he has to stop. Experimental examples: Measurement method:

[0049] Using a device according to the invention as described above, the sound wave signals from one and the same leak in the tread of a pneumatic vehicle tire were measured using a commercially available microphone and filtered using various filter units. The corresponding signal-to-noise ratio was then determined depending on the filter used and listed in Table 1 below. The rotation frequency of the pneumatic vehicle tire was approximately 600 rpm. The microphone was directed toward the tread of the pneumatic vehicle tire and was positioned 30 cm from the outer surface of the tread. The recorded sound wave signal was digitized and filtered using a conventional computer and appropriate software. Results:

[0050] The experiments were conducted as described above. The signal-to-noise ratio was then calculated using a conventional method from the magnitude of the highest frequency signal measured during the first rotation of the punctured tire, along with the background noise measured during this first rotation. The results are presented in Table 1 for each filter used. The measurement with the high-pass filter below 15 kHz (see Experiment 1) was used as a comparison and normalized to 1. Table 1: Experimental data of the measurement methods carried out according to the invention and not according to the invention experiment filter filtered out area Change in signal-to-noise ratio (SNR) 1 High pass below 15 kHz 1 2 High pass below 20 kHz 100 3 High pass below 42 kHz 100 4 Bandpass 38 to 42 kHz 1000 5 Bandpass 43 to 47 kHz 10 6 Bandpass 35 to 45 kHz 100

[0051] The 38-42 kHz bandpass filter achieved the best signal-to-noise ratio (SNR) in the chosen experiment (a 10- or 100-fold improvement compared to the high-pass filters or the other bandpass filters; compare the fourth experiment with the other experiments 2 to 6 in Table 1). What is surprising here is how important the limits of 38 kHz as the lower limit and 42 kHz as the upper limit are. Comparing Experiments 3 and 4, it is noticeable that noises with frequencies below 38 Hz degrade the SNR. However, the deterioration in the SNR is even more negative when comparing the frequencies in the range of 38 to 42 kHz (Experiment 4) with those in Experiment 5. Therefore, surprisingly, recording frequencies above 42 kHz appears to significantly degrade the SNR.

[0052] However, depending on the device's environmental parameters and the objective (there is a trade-off between robust cutoff and sensitive cutoff), other parameters and frequency ranges may also prove advantageous. Filters with cutoff frequencies below 20 kHz, on the other hand, appear to be fundamentally disadvantageous, as the proportion of background noise (engine, tire tread, etc.) increases, thus degrading the SNR (compare the first and second experiments in Table 1).

Claims

1. Vehicle comprising: - at least one vehicle wheel with a pneumatic vehicle tyre comprising a tyre interior space and - one, two or at least three soundwave receivers for repeated or continuous detection of airborne soundwave signals from the pneumatic vehicle tyre of the vehicle wheel, wherein the one soundwave receiver or one of the soundwave receivers is attached to the vehicle outside the tyre interior space of the pneumatic vehicle tyre and is designed to detect the airborne soundwaves produced by a leak in the pneumatic vehicle tyre, characterized in that the vehicle comprises at least one filter unit, which is designed to filter out signal components below 15 kHz of the airborne soundwave signals detected by one of the soundwave receivers.

2. Vehicle according to Claim 1, wherein the filter unit is designed to filter out signal components below 20 kHz of the airborne soundwave signals detected by one of the soundwave receivers, wherein the one or the at least one filter unit - is a high-pass filter, or - is a bandpass filter and the bandpass filter is designed to filter out signal components of an airborne soundwave signal with frequencies below 35 kHz and above 45 kHz, preferably signal components of an airborne soundwave signal with frequencies below 38 kHz and above 42 kHz or below 28 kHz and above 36 kHz.

3. Vehicle according to one of the preceding claims, wherein the vehicle comprises a control unit which is designed to compare - two or more than two airborne soundwave signals detected by one or more of the soundwave receivers or - two or more than two airborne soundwave signals filtered by one of the filter units, wherein the airborne soundwave signals originate from the same leak.

4. Vehicle according to one of the preceding claims, wherein the vehicle wheel of the vehicle or the pneumatic vehicle tyre of the vehicle wheel of the vehicle comprises a pressure sensor for measuring the internal tyre pressure and the pressure sensor is connected to a or the control unit, wherein the control unit is designed to determine on the basis of the drop in pressure per unit of time and on the basis of the amplitude of the detected or filtered airborne soundwave signals in this unit of time a quantitative finding about the size and / or form of the leak.

5. Vehicle according to one of the preceding claims, wherein the one soundwave receiver or one of the soundwave receivers or all of the soundwave receivers comprise(s) an acoustic lens for amplifying the airborne soundwave signals to be detected and the acoustic lens is directed at an outer wall of the pneumatic vehicle tyre of the vehicle wheel of the vehicle.

6. Vehicle according to one of the preceding claims, wherein two or three soundwave receivers are attached to the vehicle such that and are provided such that the one soundwave receiver can measure soundwaves of a leak in the tread of the one pneumatic vehicle tyre of the vehicle and the second soundwave receiver can measure soundwaves of a leak in the sidewall of the one pneumatic vehicle tyre that is the outer side wall as seen from the vehicle and optionally the third soundwave receiver can measure soundwaves of a leak in the sidewall of the one pneumatic vehicle tyre that is the inner side wall as seen from the vehicle.

7. Method for repeated or continuous detection of airborne soundwave signals from a technical rubber article, which is a pneumatic vehicle tyre of a vehicle wheel of a vehicle, wherein the method comprises the following steps: A) providing the inflated technical rubber article and one or more soundwave receivers, wherein the inflated technical rubber article - is a single-ply or multi-ply rubber layered structure with an outer wall and an inner wall, wherein the one single-ply or multi-ply rubber layered structure is preferably a sidewall or a tread of a pneumatic vehicle tyre, and - has an interior space delimited by the rubber layered structure, wherein the pressure in the interior space of the inflated technical rubber article that is delimited by the rubber layered structure is greater than the ambient pressure and the soundwave receiver is arranged outside the interior space of the inflated technical rubber article, B) creating a leak in the rubber layered structure of the technical rubber article, wherein the leak is used as a sound source for the one or more soundwave receivers and the sound source preferably has airborne soundwaves with a frequency component of 15 kHz to 75 kHz, C) repeated or continuous detection of soundwave signals from the leak - by means of the one or one of the soundwave receivers, so that the leak is used as a sound source for the soundwave receiver and temporally offset airborne soundwave signals are produced, and / or - by means of a number of the soundwave receivers, so that the leak is used as a sound source for the soundwave receivers and spatially offset airborne soundwave signals are produced, D) comparing two or more of the temporally offset and / or the spatially offset signals with one another, wherein the comparison is preferably carried out by means of a control unit, wherein, between steps C) and D), the method carries out the following step C-D): C-D) filtering out the signal components below 15 kHz of the airborne soundwave signals detected in step C) by means of a filter unit, so that filtered signals with signal components of 15 kHz or higher are produced.

8. Method according to Claim 7, wherein, at least during step C), preferably during the entire method, the technical rubber article and the soundwave receiver are moved relative to one another, wherein preferably the technical rubber article is rotated relative to the soundwave receiver.

9. Method according to either of the preceding Claims 7 and 8, wherein the filter unit - is a high-pass filter which is designed to filter out signal components below 20 kHz of the airborne soundwave signal detected by one of the soundwave receivers, or - the filter unit is a corresponding bandpass filter and step C-D) comprises: filtering out the signal components of the soundwave measurement signal with frequencies below 35 kHz and above 45 kHz, preferably below 38 kHz and above 42 kHz, so that a filtered signal with a frequency range from 35 kHz and above 45 kHz, preferably below 38 kHz and above 42 kHz, is produced.

10. Method according to one of Claims 7 to 9, wherein the leak created in step B) has a diameter in the range from 1 µm to 50 mm, preferably 0.1 mm to 20 mm.