METHOD FOR DETERMINING UNEVEN VEHICLE TIRE WEAR

Description

[0001] The invention relates to a method for determining uneven tire wear using an acceleration sensor on a tire. The invention further relates to a tire with an acceleration sensor, a system comprising a tire, and a computer program for determining uneven tire wear.

[0002] Methods and devices for determining tire wear using an accelerometer on a vehicle tire are known. The radial acceleration values ​​of the vehicle tire, output by the accelerometer, are derived over time so that tire wear and tread depth can be determined. If a vehicle tire is worn despite at least partially sufficient tread depth due to other wear patterns, such as increased wear in the shoulder area of ​​the tire, this is not reliably detected by known methods. Such methods are known from JP 2013 136297 A, JP 2011 168211 A, and US 2015 / 090023 A1.

[0003] Against this background, the invention is based on the objective of designing a method, a vehicle tire, a system comprising a vehicle tire, and a computer program product for determining tire wear in such a way that a worn vehicle tire can be reliably detected even with at least partially sufficient tread depth.

[0004] This problem is solved by a method according to the features of claim 1, as well as by a vehicle tire and a system comprising a vehicle tire and a computer program product according to a dependent claim. The subclaims relate to particularly advantageous embodiments of the invention.

[0005] According to the invention, a method for determining uneven vehicle tire wear is provided, comprising the following steps.

[0006] Acquisition of measured values ​​of the lateral acceleration at a measuring point on the tread of a vehicle tire, whereby the lateral acceleration is measured with a lateral acceleration sensor. Measured values ​​are understood to be the measured values ​​obtained by the lateral acceleration sensor or measured values ​​stored before the start of the procedure, even if these have been processed, for example, by filters or algorithms. Lateral acceleration is understood here to mean the acceleration in the direction of the tire's axis.

[0007] Identifying peaks in the measured values ​​within a viewing window, and determining the peak parameters. Determined peak parameters include peak height, peak duration, relative time interval between peaks, peak slope, and / or the area enclosed by peaks and a reference line.

[0008] The peak height is determined, for example, relative to a reference line, which can be a zero line. The slope of a peak is understood as the gradient at which it rises or falls. The area enclosed by a peak and a reference line is preferably understood as the area extending along the time axis over the duration of the peak and along the acceleration axis over the distance of the measured values ​​from the reference line.

[0009] The relative time interval is obtained by relating the time interval between two peaks to the angular velocity of the vehicle tire.

[0010] The angular velocity of the vehicle tire can be determined, for example, by identifying two similar peaks—that is, two peaks detected when the point enters the tire contact patch—from two consecutive observation windows. Each entry of the measurement point into a tire contact patch is analyzed in a separate observation window.

[0011] The determined peak parameters are compared with stored peak parameters. If a target difference between the determined peak parameters and the stored peak parameters is exceeded, a warning message is issued.

[0012] Uneven tire wear can thus be detected and reported. This helps prevent consequential damage such as significant tire air loss and accidents.

[0013] In an advantageous embodiment, uneven tire wear in the form of shoulder wear, one-sided wear, or center wear can be detected. Such uneven tire wear is increasingly common and often produces only minor changes in peak characteristics when measured values ​​are evaluated, making it difficult to identify using measurements from radial acceleration sensors.

[0014] It has proven advantageous to determine the peak duration by measuring the interval between two measurements. Measurements are selected that correspond to a specific fraction of the peak height, preferably 50%. The beginning and end of a peak can often only be determined imprecisely, so a simple determination of the peak duration is achieved by selecting measurements that represent a specific fraction of the maximum peak height. Particularly accurate and reproducible peak duration determinations have been obtained at half the peak height.

[0015] It has proven advantageous to filter the measured values ​​before identifying the peaks, preferably using a low-pass filter. Filtering the measured values, especially removing high-frequency oscillations, leads to more usable measurement data.

[0016] It has also proven advantageous to determine the peak parameters before the measured values ​​are sent to a display unit. Determining the peak parameters from the measured values ​​is advantageously performed before sending the measured values ​​to a display unit, as this reduces the amount of data to be transmitted. The measured values ​​are evaluated at the lateral acceleration sensor. The display unit is located on the vehicle and either displays the warning message directly to the driver or sends the warning message to an external device and displays it indirectly via that device.

[0017] Another preferred embodiment provides that the measured values ​​are wirelessly transmitted from a lateral acceleration sensor to a display unit. This enables a particularly simple transmission of the measured values ​​from the lateral acceleration sensor to a display unit.

[0018] It has proven advantageous for the display unit to compare the measured peak parameters with stored peak parameters and to save the measured peak parameters or, alternatively, the result of the comparison. Performing the comparison and storing the data with the display unit allows the lateral acceleration sensor to be designed in a compact and cost-effective manner. Furthermore, this allows the memory to be read even when the lateral acceleration sensor is inactive due to a vehicle standstill.

[0019] Another preferred embodiment provides that the method generates all stored measured values ​​and / or, alternatively, peak parameters, wherein the first peak parameters are not compared with stored peak parameters, and wherein the first peak parameters are stored as reference parameters. The first peak parameters are recorded at the beginning of the method, i.e., when the vehicle tires are new. The first peak parameters are suitable as reference parameters because the vehicle tire does not exhibit uneven wear in this state. Preferably, the term "first peak parameters" also refers to a plurality of first peak parameters, which are stored, for example, as a mean value of the individual first peak parameters as reference values.

[0020] Compared to reference parameters determined in other ways, this method has the advantage that specific properties of an individual tire and resulting deviations from peak parameters do not override the change in peak parameters due to uneven vehicle tire wear.

[0021] It has proven advantageous for the display unit to issue a warning message to a driver and / or an external unit. Issuing the warning message to the driver provides a simple way to inform them about uneven tire wear. However, particularly in fleet operations, a centralized warning message output via an external unit is preferable.

[0022] According to the invention, a vehicle tire is provided with a tread, preferably with a profile structure, a carcass layer, a tire belt, an inner surface, and sidewalls. A lateral acceleration sensor with a transmitter unit is arranged on the tread, wherein the lateral acceleration sensor is configured to measure the lateral acceleration of the vehicle tire during driving and preferably to detect peaks of the measured values ​​within a viewing window. The lateral acceleration sensor is configured to determine peak parameters. Peak parameters are a peak height and / or alternatively a peak duration and / or alternatively relative time intervals between the peaks and / or alternatively the slope of the peaks and / or alternatively the area enclosed by peaks and a reference line.The relative time interval is determined by relating the time interval between two peaks to the angular velocity of the vehicle tire.

[0023] Uneven tire wear can thus be detected and reported. This helps prevent consequential damage such as significant tire air loss and accidents.

[0024] A preferred embodiment provides that the lateral acceleration sensor is arranged on the inner sidewall of the tire, preferably on the inner surface of the tire, and in a centrally located area relative to the sidewalls. Such an arrangement of the lateral acceleration sensor enables the acquisition of particularly meaningful measured values.

[0025] According to the invention, a system is provided for detecting an unevenly worn vehicle tire and for issuing a warning message, for carrying out the method according to the invention.

[0026] The system includes a lateral acceleration sensor for determining measured values ​​of the lateral acceleration of a vehicle tire's tread, and a transmitter unit for sending the measured values ​​from the lateral acceleration sensor to a display unit.

[0027] The display unit is designed to output a warning message and is, for example, mounted on the vehicle. It includes a processor unit for detecting peaks, determining peak parameters, and comparing these parameters with stored peak parameters. A memory unit is provided for storing the peak parameters and / or, alternatively, the result of the comparison.

[0028] According to the invention, a vehicle is provided having a vehicle tire according to the invention, which is equipped to carry out a method according to the invention with a display unit and a storage unit.

[0029] According to the invention, a computer program product for determining a worn vehicle tire of a vehicle is provided, comprising instructions which, when the program is executed by at least one processor unit, cause it to execute the method according to the invention.

[0030] The invention allows for numerous embodiments. To further illustrate its basic principle, one of these is shown in the drawings and described below. These show in Fig. 1 a vehicle tire with a lateral acceleration sensor; Fig. 2 a comparison of lateral accelerations of a tread surface of uniformly worn vehicle tires to vehicle tires with tire shoulder wear; Fig. 3 a comparison of lateral accelerations of a tread surface of uniformly worn vehicle tires to vehicle tires with one-sided wear.

[0031] Figure 1Figure 1 shows a vehicle tire 1 with a tread 2, a tire inner surface 3, and an inner liner 4, which accommodates a lateral acceleration sensor 5. The lateral acceleration sensor 5 has an accelerometer, a processor unit, and a transmitter unit to acquire and process measured values ​​and send them to a display unit located on the vehicle.

[0032] When a point on the tread 2 and inner liner 4 of a rolling vehicle tire 1 approaches the ground, this point on the tread 2 is located within the area of ​​a tire contact patch 6. The tire contact patch 6 is a predominantly flat area of ​​the vehicle tire 1, and the distance in this area to the axis of rotation of the vehicle tire 1 is reduced. Therefore, the vehicle tire 1 experiences lateral acceleration at the inner liner 4 as it enters and exits the tire contact patch 6.

[0033] The lateral acceleration of running surfaces 2 is calculated for a region, a viewing window, in Figure 2 The graph is shown. Time is plotted on the t-axis (t), and the lateral acceleration of points on the inner liner 4 of the vehicle tire 1 is shown on the al-axis (al).

[0034] The dashed line 7 represents the lateral acceleration at the inner liner 4 of a uniformly worn vehicle tire 1 in the area of ​​the tire contact patch 6. At the beginning of the observation window, shown on the left, the lateral acceleration is slightly positive. It then drops sharply to a minimum value in the form of a peak P and subsequently approaches a lateral acceleration of approximately zero. Upon leaving the tire contact patch 6, the lateral acceleration rises sharply to a maximum value in the form of a peak P, before subsequently approaching zero.

[0035] The solid line 8 represents the lateral acceleration at the inner liner 4 of a vehicle tire 1 in the area of ​​the tire contact patch 6, where the vehicle tire 1 exhibits shoulder wear. Compared to the dashed line 7, it is evident in the area of ​​the first peak P of the dashed line 7 that the solid line 8 does not have such a pronounced peak P in this area. Instead, the solid line 8 shows two less pronounced minimum values. In the area of ​​the second peak P of the dashed line 7, the solid line 8 also shows a peak P, which, however, reaches its maximum value at a later time. The solid line 8 then also approaches a zero value.

[0036] In Figure 3 A further lateral acceleration at the inner liner 4 is shown for a viewing window. The dashed line 7 corresponds to the dashed line 7 of the Figure 2and represents the lateral acceleration at the inner liner 4 of a uniformly worn vehicle tire 1. The solid line 9 represents an acceleration at the inner liner 4 with one-sided tire wear. The solid line 9 runs above the dashed line 7 in the area before the first peak P of the dashed line 7. The solid line 9 also exhibits a significantly less pronounced negative peak P. The positive peak P of the solid line 9 has a significantly larger area relative to the zero line. Furthermore, the peak P is shifted to a later time. Reference symbol list

[0037] 1 Vehicle tire 2 Tread 3 Tire inside 4 Inner liner 5 Lateral acceleration sensor 6 Tire tread 7 Dashed line 8 Solid line 9 Solid line alal axis PPeak tt axis

Claims

1. Method for determining uneven vehicle tyre wear, having the steps of: - recording measured values of a lateral acceleration of a measurement point on the inner liner (4) of a vehicle tyre (1) by means of a lateral acceleration sensor (5), - finding peaks (P) of the measured values by means of the lateral acceleration sensor (5), wherein the lateral acceleration sensor (5) is used to determine peak parameters, namely a peak height and / or a peak duration and / or a relative time interval between peaks, wherein the relative time interval is determined by relating the time interval between two peaks (P) to the angular velocity of the vehicle tyre (1), and / or the edge steepness of the peaks and / or the area enclosed by the peaks with a reference line, - comparing the determined peak parameters with stored peak parameters, - outputting a warning message when a setpoint difference between the determined peak parameters and the stored peak parameters is exceeded.

2. Method according to Claim 1, characterized in that the uneven vehicle tyre wear is tyre shoulder wear or one-sided vehicle tyre wear (1) or tyre centre wear.

3. Method according to Claim 1 or 2, characterized in that, when a peak duration is determined, the peak duration is determined by means of the duration between two measured values, wherein measured values which correspond to a certain proportion of the peak height of the peak (P), namely 50% of the peak height, are selected.

4. Method according to one of the preceding claims, characterized in that the measured values are filtered prior to finding the peaks (P), preferably with a low pass filter.

5. Method according to one of the preceding claims, characterized in that the peak parameters are determined prior to outputting the measured values to a display unit.

6. Method according to one of the preceding claims, characterized in that the measured values are output wirelessly from a lateral acceleration sensor (4) to a display unit.

7. Method according to Claim 6, characterized in that the display unit compares the determined peak parameters with stored peak parameters and stores the determined peak parameters and / or the result of the comparison.

8. Method according to one of the preceding claims, characterized in that the method generates all stored measured values and / or peak parameters, wherein first peak parameters are not compared with stored peak parameters, wherein first peak parameters are stored as reference parameters.

9. Method according to one of the preceding claims, characterized in that the display unit outputs a warning message to a vehicle driver and / or a unit outside the vehicle.

10. Vehicle tyre (1) having a tread (2), preferably with a profile structure, a carcass ply, a tyre belt, a tyre inner side (3), an inner liner (4) and side walls, wherein a lateral acceleration sensor (5) with a transmitting unit is arranged on the tread (2), wherein the lateral acceleration sensor (5) is configured to measure the lateral acceleration of the vehicle tyre (1) during a journey, characterized in that the lateral acceleration sensor (5) is configured to find peaks (P) of the measured values, wherein the lateral acceleration sensor (4) is configured to determine peak parameters, namely a peak height and / or a peak duration and / or relative time intervals between the peaks (P), wherein the relative time interval is determined by relating the time interval between two peaks (P) to the angular velocity of the vehicle tyre (1), and / or the edge steepness of the peaks (P) and / or the area enclosed by the peaks (P) with a reference line.

11. Vehicle tyre (1) according to Claim 10, characterized in that the lateral acceleration sensor (4) is arranged on the tyre inner side (3) of the tread (2), preferably on the tyre inner side (3), and in a region arranged centrally relative to the side walls.

12. System for determining an unevenly worn vehicle tyre (1) and for outputting a warning message, for carrying out the method according to Claim 1, comprising: - a lateral acceleration sensor (4) for determining measured values of a lateral acceleration of a tread (2) of a vehicle tyre (1), comprising a transmitting unit for transmitting the measured values from the lateral acceleration sensor (4) to a display unit, - a display unit for outputting a warning message, which is arranged in particular on the vehicle, - a processor unit for finding peaks (P) and determining peak parameters and for comparing the determined peak parameters with stored peak parameters, - a storage unit for storing the peak parameters and / or the result of the comparison.

13. Vehicle comprising a vehicle tyre (1) according to Claim 10, which is configured to carry out a method according to Claim 1 with a display unit and a storage unit.

14. Computer program product for determining a worn vehicle tyre (1) of a vehicle, comprising instructions which, when the program is executed by at least one processor unit, causes the latter to carry out the method according to Claim 1.