METHOD AND DEVICE FOR DETERMINING A TIRE-CHARACTERISTIC INFLUENCE CHARACTERISTIC VALUE

Description

[0001] The invention relates to a method and a device for determining the load history of a tire, in which load values ​​applied to the tire are determined, in particular by a sensor that can be attached to the tire.

[0002] US 2007 / 095446 A1 discloses using sensors attached to a tire to determine tire-specific variables, such as tire pressure or tire temperature, and transmitting these values ​​to a control unit via a radio signal. Such sensors can also measure tire mileage and tread depth, with the individual measurement data being stored on the sensor for readout at any time, as described, for example, in US 2006 / 006991 A1.

[0003] Furthermore, it is known that the load values ​​acting on vehicle tires, particularly wheel load and tread depth, together with tire temperature, have a significant influence on tire durability, which is commonly referred to as "endurance." However, these tire-specific influencing variables, particularly wheel load and / or tread depth, cannot currently be measured directly using appropriate sensors at a reasonable cost and incorporated into endurance monitoring.

[0004] From WO 2017 / 032466A1 and DE 10 2015 216 210 A1, a method and a sensor with associated control unit are known which determine the wheel load and the tread depth via a mathematical mapping from the course of the radial acceleration of the tire on the inner liner.

[0005] US 2018 / 0023998 A1 discloses a device and method for recording a vehicle's load history. Load ranges are defined with associated counters, the total weight of the vehicle is determined at various points in time, the measured total weight is assigned to the corresponding load range, and its counter is incremented. In this way, it can be determined whether the vehicle has been overloaded in order to evaluate warranty claims in the event of drivetrain damage. Determining the load history of an individual tire is not possible or intended with the known device and method.

[0006] A disadvantage of the methods and sensors known to date is that no load history can be created or made accessible over the operating or service life of the tire that could be used to assess endurance.

[0007] The object of the invention is therefore to propose a method and a device of the type mentioned at the outset which overcome the disadvantages of the prior art.

[0008] To achieve the stated object, the invention proposes the design of a method according to the features of patent claim 1.

[0009] A device according to the invention for solving the stated problem is the subject of patent claim 8.

[0010] Advantageous embodiments and further developments of the invention are the subject of the dependent claims.

[0011] The method according to the invention provides for defining load ranges of a predetermined width, and providing a counter for each load range. The load values ​​are then determined using suitable sensors on the tire in a continuous series at predetermined time intervals and assigned to the load ranges. Each assignment results in an increment of the corresponding counter. The counters or their counter readings are stored and provided as a load history and read out as needed.

[0012] Thus, according to the invention, it is possible to determine the applied load values ​​in a sensor attached to the tire at predetermined time intervals, which, however, are not stored directly for the purpose of creating a load history and reducing the data volume, but are assigned to predetermined load ranges and lead to an increase in the assigned counter.

[0013] According to the invention, a corresponding digital counter is maintained for defined load ranges or ranges of the correlated variables, which is incremented by a corresponding step size in order to generate the load history of the tire over a certain period of time or even over the entire service life of the tire by summing up the counter readings.

[0014] The defined load ranges are defined before the tire is put into operation based on the expected operating conditions and the correlated variables determined by the sensor used. For example, by determining or calculating wheel loads as load values ​​and specifying a range of 100 kg for passenger car tires and 500 kg for truck tires. By stringing together a large number of such successive load ranges with an exemplary range of 100 kg, the entire expected spectrum of load values ​​can be covered and evaluated with corresponding counters per load range. The same applies to other determined load values ​​or sensor variables instead of the wheel load.

[0015] Ideally, the range widths are divided as finely as possible and the entire range covered by all load ranges is dimensioned as wide as possible, whereby the actual range width is selected depending on the available storage.

[0016] According to one proposal of the invention, in addition to the load ranges defined on the basis of the expected operating conditions, a lower and an upper limit are defined for the load value, which are expected to be minimum and maximum, and the load ranges with their associated counters are defined between these two limit values. A further counter is provided for determined load values ​​below the lower limit and for determined load values ​​above the upper limit. When determining wheel loads, the unladen weight of the vehicle can be used as the lower limit, for example, and the maximum weight of the vehicle on which the tire is mounted can be used as the upper limit. The result obtained by evaluating all of the counters is a load histogram with an underflow and an overflow range.

[0017] According to a further proposal of the invention, the load values ​​can be determined in particular by determining the radial acceleration of the tire, for example by analyzing the so-called contact patch pattern, as is known in principle from WO 2017 / 032466A1, the disclosure of which is incorporated herein by reference, whereby the applied wheel load and / or the tread depth can be deduced.

[0018] According to a further proposal of the invention, the time intervals in which the load values ​​are determined as a continuous series and assigned to the load ranges by incrementing the corresponding counter can be selected to be of equal or different sizes. If the time intervals are of equal size, the corresponding counter is preferably incremented by 1 when a load value is assigned to a specific load range. If the time intervals are of unequal size, the counter is incremented by a value representing the size of the time interval, for example, by the length of the time interval in seconds or minutes.

[0019] The individual meters or their meter readings are stored and can be read out as load history if required. According to a further proposal of the invention, a wireless interface, for example a Bluetooth connection, can preferably be provided for this purpose, which wirelessly couples the meter to a corresponding reading device in order to read out the meter readings.

[0020] In addition to creating a one-dimensional load histogram over time, the invention also provides for the creation of a multi-dimensional load histogram. According to a further proposal of the invention, in addition to the load value, the temperature and / or the number of tire revolutions, and thus the distance traveled, can be determined and stored together with the counters and provided as a load history. For example, by additionally measuring the tire temperature, a two-dimensional load-temperature histogram of the tire can be provided and read out as needed.

[0021] The number of revolutions and thus the distance traveled by the tire can not only be stored directly, but can also be used as a default for incrementing the counter readings of the respective assigned load values ​​to load ranges. So, when a load value is assigned to a load range, the assigned counter is not incremented by 1, but rather by the distance traveled, determined, for example, from the number of revolutions. In simplified terms, this distance can also be replaced by the radial acceleration measured simultaneously with the load and, if applicable, the temperature, or the square root of this radial acceleration.

[0022] The device proposed within the scope of the invention for determining a tire-characteristic influencing variable comprises a sensor which can be attached to the tire, preferably to its inner liner, for determining load values ​​applied to the tire and is characterized in that the sensor comprises an evaluation unit which assigns determined load values ​​to definable load ranges and comprises counters assigned to the load ranges, by means of which each assignment of a load value to a load range can be counted and stored and can be output as a load history of the tire as required.

[0023] The sensor can be designed in particular to determine the radial acceleration of the tire in the so-called contact patch passage in order to determine the applied wheel load and the tread depth of the tire as a load value from the measured values ​​by means of a mathematical calculation, as described, for example, in WO 2017 / 032466.

[0024] To read the load history as needed, the sensor advantageously includes a radio interface, for example a Bluetooth interface.

[0025] Such a sensor can be glued or attached to the tire in a conventional manner, preferably on the inner liner, to determine the desired load values. The sensor also includes the evaluation unit and the counters assigned to the respective definable load ranges. Furthermore, such a sensor can also have extended functionality, for example, by measuring the tire temperature and storing it as part of the provided load history and / or determining the number of tire revolutions to measure the total tire mileage and incorporate it into the provided load history.

[0026] Using the method and device according to the invention, a tire load history can be created in real time over the tire's service life from load values ​​or variables that strongly correlate with the load. This can be made available and read at any time, for example, to perform a tire endurance assessment. This tire assessment can be performed both during the tire's service life and at the end of its service life. No additional hardware is required on the vehicle itself to store the load history, as this storage takes place entirely on the sensor.

Claims

1. Method for determining the load history of a tyre, in which load values applied to the tyre are determined by a sensor attached to the tyre, characterized in that load ranges of a predetermined range width are defined and a counter is provided for each load range and the load values are determined as a continuous series at predetermined time intervals and are assigned to the load ranges while incrementing the associated counter, wherein the counters are stored and provided as a load history and read out as required.

2. Method according to Claim 1, characterized in that a lower and an upper limit value are defined for the load value, between which the load ranges are defined, and a further counter for determined load values below the lower limit value and a further counter for determined load values above the upper limit value are provided.

3. Method according to either of Claims 1 and 2, characterized in that the load values are determined by determining the radial acceleration of the tyre.

4. Method according to one of Claims 1 to 3, characterized in that the time intervals are selected to be the same or different.

5. Method according to Claim 4, characterized in that, when a load value is assigned to a load range, the associated counter is incremented by the value 1 if the time intervals are the same and is incremented by a value representing the time interval if the time intervals are different.

6. Method according to one of Claims 1 to 5, characterized in that the counters are read out wirelessly.

7. Method according to one of Claims 1 to 6, characterized in that the temperature and / or the revolutions of the tyre is / are determined and stored together with the counters.

8. Apparatus for determining the load history of a tyre, comprising a sensor that can be attached to the tyre and is intended to determine load values applied to the tyre, characterized in that the sensor comprises an evaluation unit that assigns determined load values to definable load ranges and comprises counters which are assigned to the load ranges and by means of which each assignment of a load value to a load range can be counted and stored and can be output as a load history of the tyre as required.

9. Apparatus according to Claim 8, characterized in that the sensor is designed to determine the radial acceleration of the tyre.

10. Apparatus according to Claim 8 or 9, characterized in that the sensor comprises a radio interface for outputting the load history.

11. Apparatus according to one of Claims 8 to 10, characterized in that the sensor captures the temperature and / or the revolutions of the tyre and the values determined by the sensor can be stored together with the counters.