JP5898519B2 - Tire wear amount estimation method and tire wear amount estimation device - Google Patents

Tire wear amount estimation method and tire wear amount estimation device Download PDF

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JP5898519B2
JP5898519B2 JP2012033091A JP2012033091A JP5898519B2 JP 5898519 B2 JP5898519 B2 JP 5898519B2 JP 2012033091 A JP2012033091 A JP 2012033091A JP 2012033091 A JP2012033091 A JP 2012033091A JP 5898519 B2 JP5898519 B2 JP 5898519B2
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differential peak
tire
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剛 真砂
剛 真砂
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Bridgestone Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/24—Wear-indicating arrangements
    • B60C11/246—Tread wear monitoring systems

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Description

本発明は、タイヤトレッドの内面側に配置された加速度センサーの出力信号を用いて、当該タイヤの摩耗量を推定する方法とその装置に関するものである。   The present invention relates to a method and an apparatus for estimating the amount of wear of a tire using an output signal of an acceleration sensor arranged on the inner surface side of a tire tread.

従来、タイヤの摩耗を推定する方法としては、タイヤトレッドの溝部もしくはトレッドゴムの内部などに磁性材料や導電ゴムから成る検知体を埋め込み、車体側にセンサーを配置して、タイヤの摩耗により検知体が摩耗してセンサーの検出信号が変化することからタイヤの摩耗を推定する方法（例えば、特許文献１参照）や、タイヤトレッドに有臭ガスや着色ガスを予め挿入しておき、トレッドの摩耗が進行しガス封入部が空気中に露出して有臭ガスや着色ガス空気中に放出されることで、タイヤが摩耗していることを周囲に認識させる方法（例えば、特許文献２参照）などが提案されている。   Conventionally, as a method of estimating tire wear, a detector made of a magnetic material or conductive rubber is embedded in a groove of a tire tread or the inside of a tread rubber, and a sensor is disposed on the vehicle body side. The wear signal of the tire changes from the detection signal of the sensor due to wear of the tire (see, for example, Patent Document 1), or odorous gas or coloring gas is inserted in the tire tread in advance, A method (for example, refer to Patent Document 2) that recognizes that the tire is worn by proceeding and exposing the gas sealing portion to the air and releasing it into the odorous gas or colored gas air. Proposed.

しかしながら、タイヤトレッドにセンサーや磁性体などの異物を挿入すると、挿入した部位近辺に応力が集中して故障の核となる可能性があるため、タイヤの耐久性が低下することが懸念される。また、有臭ガスや着色ガスを用いる方法では、摩耗が進行したか否かの判定しか行えないので、トレッドの摩耗する過程における摩耗状態の変化を捉えることはできないといった問題があった。   However, if a foreign object such as a sensor or a magnetic material is inserted into the tire tread, stress may concentrate near the inserted portion and become the core of failure, so there is a concern that the durability of the tire may be reduced. In addition, the method using odorous gas or colored gas can only determine whether or not the wear has progressed, so there is a problem that it is impossible to capture the change in the wear state during the process of wearing the tread.

そこで、タイヤのインナーライナー部のタイヤの幅方向中心に加速度センサーを設置して、この加速度センサーを用いて検出したタイヤ径方向の加速度波形を微分した微分加速度波形の接地端におけるピーク値である微分ピーク値を求めるとともに、接地面外部分の特定位置かつ特定周波数範囲における振動レベルである帯域値を算出し、前記帯域値に基づいて前記微分ピーク値を補正し、この補正された微分ピーク値からタイヤの摩耗の度合いを推定する方法が提案されている（例えば、特許文献３参照）。
これにより、路面状態によらず、タイヤの摩耗状態を精度よくかつ安定して推定できるとともに、センサーがタイヤの内面側に設置されているので、センサー及びタイヤの耐久性が向上する。 Therefore, an acceleration sensor is installed at the center of the tire in the width direction of the inner liner portion of the tire, and a differential value that is a peak value at the contact end of the differential acceleration waveform obtained by differentiating the acceleration waveform in the tire radial direction detected using the acceleration sensor. While obtaining a peak value, calculating a band value that is a vibration level in a specific position and a specific frequency range outside the ground plane, correcting the differential peak value based on the band value, and from the corrected differential peak value A method for estimating the degree of tire wear has been proposed (see, for example, Patent Document 3).
Accordingly, the wear state of the tire can be estimated accurately and stably regardless of the road surface state, and the sensor and the tire are improved in durability because the sensor is installed on the inner surface side of the tire.

特開２００３−２１４８０８号公報JP 2003-214808 A 特開２００５−２８９５０号公報JP 2005-28950 A ＷＯ ２００９/１５７５１６ Ａ１WO 2009/157516 A1

しかしながら、前記特許文献３に記載の方法では、微分ピーク値及び帯域値にバラつきがあることから、タイヤの摩耗の度合いの推定精度が十分に高いとはいえなかった。
そこで、タイヤ径方向の加速度波形を複数回抽出して微分ピーク値の平均値と帯域値の平均値を求め、微分ピーク値の平均値を帯域値の平均値で補正した値に基づいてタイヤの摩耗の度合いを推定することが考えられるが、単に平均値を用いただけでは、タイヤの摩耗の度合いの推定精度を十分に高めることは困難であった。 However, in the method described in Patent Document 3, since the differential peak value and the band value vary, it cannot be said that the estimation accuracy of the degree of tire wear is sufficiently high.
Therefore, the tire radial acceleration waveform is extracted multiple times to obtain the average value of the differential peak value and the average value of the band value, and based on the value obtained by correcting the average value of the differential peak value with the average value of the band value. Although it is conceivable to estimate the degree of wear, it has been difficult to sufficiently improve the estimation accuracy of the degree of wear of a tire simply by using an average value.

本発明は、従来の問題点に鑑みてなされたもので、路面状態によらず、タイヤの摩耗状態を精度よくかつ安定して推定できる方法とその装置を提供することを目的とする。   The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a method and apparatus capable of accurately and stably estimating the wear state of a tire regardless of the road surface state.

本願発明は、加速度センサーを用いて検出したタイヤ径方向加速度からタイヤトレッドの摩耗量を推定するタイヤ摩耗量推定方法であって、タイヤトレッドの内面に配置された加速度センサーを用いて当該タイヤのタイヤ径方向加速度を検出するステップ（ａ）と、前記検出されたタイヤ径方向加速度から接地面近傍を含むタイヤ径方向加速度波形を抽出するステップ（ｂ）と、前記タイヤ径方向加速度波形の踏み込み前領域の波形から、予め設定した特定周波数帯域の振動レベルである踏み込み前帯域値を算出するステップ（ｃ）と、前記タイヤ径方向加速度波形を微分して微分加速度波形を求めるステップ（ｄ）と、前記微分加速度波形から当該微分加速度波形の接地端部に出現するピークの大きさである微分ピーク値を算出するステップ（ｅ）と、前記ステップ（ａ）〜（ｅ）を複数回繰り返して、複数の互いに異なる踏み込み前帯域値のそれぞれについて、前記微分ピーク値を算出するステップ（ｆ）と、前記ステップ（ｆ）で算出された複数の踏み込み前帯域値と微分ピーク値とから、前記踏み込み前帯域値と前記微分ピーク値との関係を示す近似式、もしくは、前記踏み込み前帯域値に対する前記微分ピーク値をプロットして得られる近似線を求めるステップ（ｇ）と、前記近似式もしくは近似線から予め設定された基準踏み込み前帯域値に対応する微分ピーク値である基準微分ピーク値を算出するステップ（ｈ）と、前記算出された基準微分ピーク値から当該タイヤの摩耗量を推定するステップ（ｉ）と、を備えることを特徴とする。
このように、踏み込み前帯域値と微分ピーク値の関係を示す近似式もしくは近似線を作成し、この近似式もしくは近似線における予め設定された基準踏み込み前帯域値に対応する微分ピーク値に基づいてタイヤの摩耗量を推定したので、単なる平均値を用いては得られない、路面の凹凸度合いである路面粗さにより異なる踏み込み前帯域値と微分ピーク値の関係を考慮したタイヤの摩耗量の推定を行うことができる。したがって、路面の状態によらず、タイヤの摩耗量を精度よく推定することができる。
The present invention relates to a tire wear amount estimation method for estimating a wear amount of a tire tread from a tire radial acceleration detected using an acceleration sensor, the tire of the tire using an acceleration sensor disposed on an inner surface of the tire tread. A step (a) of detecting radial acceleration, a step (b) of extracting a tire radial acceleration waveform including the vicinity of a ground contact surface from the detected tire radial acceleration, and a region before stepping on the tire radial acceleration waveform A step (c) of calculating a pre-depression band value which is a vibration level in a predetermined specific frequency band from the waveform of step (d), a step (d) of obtaining a differential acceleration waveform by differentiating the tire radial acceleration waveform, and A step of calculating a differential peak value, which is a size of a peak appearing at a grounded end portion of the differential acceleration waveform from the differential acceleration waveform. And (e), the step (a) ~ (e) a repeated multiple times, for each of a plurality of different depression before the bandwidth values, and step (f) to calculate the differential peak value, said step (f) From the plurality of pre-depression band values and differential peak values calculated in Step 1, plot an approximate expression indicating the relationship between the pre-depression band value and the differential peak value, or the differential peak value with respect to the pre-depression band value. A step (g) of obtaining an approximate line obtained by calculating a reference differential peak value that is a differential peak value corresponding to a reference pre-step-in band value set in advance from the approximate expression or the approximate line; And (i) estimating the amount of wear of the tire from the calculated reference differential peak value.
In this way, an approximate expression or approximate line indicating the relationship between the pre-depression band value and the differential peak value is created, and based on the differential peak value corresponding to the preset reference pre-depression band value in the approximate expression or approximate line. Estimating the amount of tire wear taking into account the relationship between the pre-stepping zone value and the differential peak value, which differ depending on the road surface roughness, which is the degree of road surface unevenness, which cannot be obtained by simply using the average value because the amount of tire wear has been estimated. It can be performed. Therefore, the amount of tire wear can be accurately estimated regardless of the road surface condition.

また、本願発明は 前記ステップ（ｆ）では、前記微分ピーク値を前記踏み込み前帯域値毎に計数し、前記計数された踏み込み前帯域値毎の微分ピーク値の数が予め設定された個数であるＮ個に全て達するまで、前記踏み込み前帯域値と前記微分ピーク値と算出する操作を繰り返し、前記ステップ（ｇ）では、前記踏み込み前帯域値毎に求められたＮ個の微分ピーク値の平均値である微分ピーク平均値を前記踏み込み前帯域値毎に算出した後、前記踏み込み前帯域値と微分ピーク平均値との関係を示す近似式、もしくは、前記踏み込み前帯域値に対する微分ピーク平均値をプロットして得られる近似線を求め、前記ステップ（ｈ）では、前記近似式もしくは近似線から予め設定された基準踏み込み前帯域値に対応する微分ピーク平均値を算出してこれを基準微分ピーク値とし、前記ステップ（ｉ）では、前記算出された基準微分ピーク値と、予め求めておいた基準微分ピーク値とタイヤの摩耗量との関係を示すマップとから当該タイヤの摩耗量を推定することを特徴とする。
このように、帯域レベル毎に微分ピーク値の平均値（Ｎ個の平均値）を求め、帯域レベルと微分ピーク値の平均値との関係から基準微分ピーク値を求めるようにしたので、微分ピーク値のバラつきによる影響を更に低減することができる。
また、算出された基準微分ピーク値と、予め求めておいた基準微分ピーク値とタイヤの摩耗量との関係を示すマップとを比較してタイヤの摩耗量を推定するようにしたので、タイヤの摩耗量の推定精度を更に向上させることができる。
なお、前記微分ピーク値Ｖを前記踏み込み前帯域値毎に計数する際には、一般に行われているように、踏み込み前帯域値Ｐを所定のレベル幅Δを有する離散的な踏み込み前帯域値Ｐiとし、この離散的な踏み込み前帯域値Ｐiを中心にした［Ｐi−Δ/２，Ｐi＋Δ/２］の領域内に入るＰに対応する微分ピーク値を踏み込み前帯域値Ｐiに対応する微分ピーク値Ｖiとして計数することはいうまでもない。 In the present invention, in the step (f), the differential peak value is counted for each pre-depression band value, and the number of differential peak values for each pre-depression band value is a preset number. The operation of calculating the pre-stepping zone value and the differential peak value is repeated until all N pieces are reached, and in step (g), the average value of the N differential peak values obtained for each of the pre-stepping zone values. After calculating the differential peak average value for each of the pre-depression band values, an approximate expression showing the relationship between the pre-depression band value and the differential peak average value, or plotting the differential peak average value with respect to the pre-depression band value In the step (h), a differential peak average value corresponding to a preset reference step-in band value is calculated from the approximate expression or the approximate line. In this step (i), the tire is determined based on the calculated reference differential peak value and a map indicating the relationship between the previously determined reference differential peak value and the amount of tire wear. The amount of wear is estimated.
In this way, the average value of the differential peak value (N average values) is obtained for each band level, and the reference differential peak value is obtained from the relationship between the band level and the average value of the differential peak value. It is possible to further reduce the influence due to the variation in values.
In addition, the tire wear amount is estimated by comparing the calculated reference differential peak value with a map indicating the relationship between the reference differential peak value obtained in advance and the tire wear amount. The estimation accuracy of the wear amount can be further improved.
When the differential peak value V is counted for each pre-depression band value, the pre-depression band value P is a discrete pre-depression band value P having a predetermined level width Δ, as is generally done. i, and the differential peak value corresponding to P that falls within the region of [P i −Δ / 2, P i + Δ / 2] centered on the discrete pre-step-down band value P i is set to the pre-step-down band value P i. Needless to say, it is counted as the differential peak value V i corresponding to.

また、本願発明は、加速度センサーを用いて検出したタイヤ径方向加速度からタイヤトレッドの摩耗量を推定するタイヤ摩耗量推定装置であって、タイヤトレッドの内面側に配置されてタイヤ径方向加速度を検出する加速度センサーと、前記加速度センサーの出力信号から、接地面近傍を含むタイヤ径方向加速度波形を抽出する加速度波形抽出手段と、前記タイヤ径方向加速度波形の踏み込み前領域の波形から、予め設定した特定周波数帯域の振動レベルである踏み込み前帯域値を算出する帯域値算出手段と、前記タイヤ径方向加速度波形を微分して微分加速度波形を求める微分演算手段と、前記微分加速度波形における接地端部のピーク値である微分ピーク値を算出する微分ピーク値算出手段と、前記微分ピーク値を踏み込み前帯域値毎に計数する計数手段と、前記計数された微分ピーク値の数が予め設定された個数であるＮ個に達したときに、前記微分ピーク値の平均値である微分ピーク平均値を算出する微分ピーク平均値算出手段と、前記踏み込み前帯域値と微分ピーク平均値との関係を示す近似式、もしくは、前記踏み込み前帯域値に対する微分ピーク平均値をプロットして得られる近似線を求め、前記近似式もしくは近似線から予め設定された基準踏み込み前帯域値に対応する微分ピーク平均値である基準微分ピーク値を算出する基準微分ピーク値算出手段と、予め求めておいた基準微分ピーク値とタイヤの摩耗量との関係を示すマップを記憶する記憶手段と、前記算出された基準微分ピーク値と前記記憶されたマップとから、当該タイヤの摩耗量を推定する摩耗量推定手段と、を備えることを特徴とする。
このような構成を採ることにより、路面の状態等による踏み込み前帯域値や微分ピーク値のバラつきによる影響を最小限にした、推定精度の高いタイヤの摩耗量推定装置を実現できる。 Further, the present invention is a tire wear amount estimation device for estimating a tire tread wear amount from a tire radial acceleration detected using an acceleration sensor, and is disposed on an inner surface side of the tire tread to detect a tire radial acceleration. An acceleration waveform extracting means for extracting a tire radial acceleration waveform including the vicinity of a ground contact surface from an output signal of the acceleration sensor, and a predetermined identification from a waveform in a region before stepping on the tire radial acceleration waveform. Band value calculating means for calculating a pre-depression band value that is a vibration level in a frequency band, differential calculating means for differentiating the tire radial acceleration waveform to obtain a differential acceleration waveform, and a peak at a ground end in the differential acceleration waveform Differential peak value calculating means for calculating a differential peak value that is a value, and stepping on the differential peak value for each pre-band value A counting means for counting and a differential peak average for calculating a differential peak average value that is an average value of the differential peak values when the number of the counted differential peak values reaches a preset number N An approximate expression showing a relationship between the value calculation means and the band value before stepping and the differential peak average value, or an approximate line obtained by plotting the differential peak average value with respect to the band value before stepping, the approximate expression or Reference differential peak value calculating means for calculating a reference differential peak value, which is a differential peak average value corresponding to a band value before reference depression, which is set in advance from an approximate line, and a reference differential peak value determined in advance and a tire wear amount Wear amount estimation for estimating the wear amount of the tire from the storage means for storing a map showing the relationship between the calculated reference differential peak value and the stored map Characterized in that it comprises a stage, a.
By adopting such a configuration, it is possible to realize a tire wear amount estimation apparatus with high estimation accuracy that minimizes the influence of variations in the pre-depression band value and differential peak value due to road surface conditions and the like.

なお、前記発明の概要は、本発明の必要な全ての特徴を列挙したものではなく、これらの特徴群のサブコンビネーションもまた、発明となり得る。   The summary of the invention does not list all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

本実施の形態に係るタイヤ摩耗量推定装置の構成を示す図である。It is a figure which shows the structure of the tire wear amount estimation apparatus which concerns on this Embodiment. 加速度センサーの取付け例を示す図である。It is a figure which shows the example of attachment of an acceleration sensor. 加速度波形と微分加速度波形の一例を示す図である。It is a figure which shows an example of an acceleration waveform and a differential acceleration waveform. 本発明によるタイヤ摩耗量推定方法を示すフローチャートである。It is a flowchart which shows the tire wear amount estimation method by this invention. 微分ピーク平均値の算出方法を説明するための図である。It is a figure for demonstrating the calculation method of a differential peak average value. 基準微分ピーク値の算出方法を説明するための図である。It is a figure for demonstrating the calculation method of a reference | standard differential peak value. 踏み込み前帯域値と微分ピーク平均値との関係を示す図である。It is a figure which shows the relationship between a step-down zone value and a differential peak average value. 微分ピーク平均値とタイヤ摩耗量との関係を示す図である。It is a figure which shows the relationship between a differential peak average value and the amount of tire wear.

以下、実施の形態を通じて本発明を詳説するが、以下の実施の形態は特許請求の範囲に係る発明を限定するものでなく、また、実施の形態の中で説明される特徴の組み合わせの全てが発明の解決手段に必須であるとは限らない。   Hereinafter, the present invention will be described in detail through embodiments, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

図１はタイヤ摩耗量推定装置１０の構成を示す機能ブロック図で、同図において、１１は加速度センサー、１２は加速度波形抽出手段、１３は帯域値算出手段、１４は微分加速度波形演算手段、１５は微分ピーク値算出手段、１６は微分ピーク平均値算出手段、１７は基準微分ピーク値算出手段、１８は記憶手段、１９はタイヤ摩耗量推定手段である。
加速度センサー１１がセンサー部１０Ａを構成し、加速度波形抽出手段１２からタイヤ摩耗量推定手段１９までの各手段が記憶・演算部１０Ｂを構成する。
記憶・演算部１０Ｂを構成する各手段は、例えば、コンピュータのソフトウェア及びＲＡＭ等の記憶装置により構成され、図示しない車体側に配置される。
加速度センサー１１は、図２に示すように、タイヤ１のインナーライナー部２の同図のＣＬで示すタイヤ幅方向中心に、検出方向がタイヤ径方向になるように配置されて、タイヤトレッド３のセンター部４の内面に作用するタイヤ径方向加速度を検出する。なお、加速度センサー１１の出力信号を演算部１０Ｂに送る構成としては、例えば、図２に示すように、インナーライナー部２もしくはホイール５に送信器１１Ｆを設置して、加速度センサー１１の出力信号をそれぞれ図示しない増幅器で増幅した後、無線にて車体側に配置された記憶・演算部１０Ｂに送信する構成とすることが好ましい。なお、記憶・演算部１０Ｂをタイヤ１側に設けてタイヤ摩耗量推定手段の推定結果を車体側の図示しない車両制御装置に送信する構成としてもよい。 FIG. 1 is a functional block diagram showing the configuration of the tire wear amount estimating apparatus 10, in which 11 is an acceleration sensor, 12 is an acceleration waveform extracting means, 13 is a band value calculating means, 14 is a differential acceleration waveform calculating means, 15 Is a differential peak value calculating means, 16 is a differential peak average value calculating means, 17 is a reference differential peak value calculating means, 18 is a storage means, and 19 is a tire wear amount estimating means.
The acceleration sensor 11 constitutes a sensor unit 10A, and each unit from the acceleration waveform extraction unit 12 to the tire wear amount estimation unit 19 constitutes a storage / calculation unit 10B.
Each means constituting the storage / calculation unit 10B is constituted by, for example, a computer software and a storage device such as a RAM, and is disposed on the vehicle body side not shown.
As shown in FIG. 2, the acceleration sensor 11 is arranged at the center of the tire width direction indicated by CL of the inner liner portion 2 of the tire 1 so that the detection direction is the tire radial direction. The tire radial acceleration acting on the inner surface of the center portion 4 is detected. In addition, as a structure which sends the output signal of the acceleration sensor 11 to the calculating part 10B, as shown in FIG. 2, the transmitter 11F is installed in the inner liner part 2 or the wheel 5, for example, and the output signal of the acceleration sensor 11 is sent. It is preferable that the signal is amplified by an amplifier (not shown) and then wirelessly transmitted to the storage / calculation unit 10B disposed on the vehicle body side. The storage / calculation unit 10B may be provided on the tire 1 side, and the estimation result of the tire wear amount estimation means may be transmitted to a vehicle control device (not shown) on the vehicle body side.

加速度波形抽出手段１２は、加速度センサー１１から出力されるタイヤトレッド３のセンター部４に作用するタイヤ径方向加速度の大きさを表す信号からセンター部４におけるタイヤ接地面近傍のタイヤ径方向加速度の時系列波形であるタイヤ径方向加速度波形（以下、加速度波形という）を抽出する。加速度波形としては、必ずしもタイヤ１周分の波形である必要はなく、接地面近傍の波形を含んでいれば、例えば、１周の６０％程度の長さであってもよい。
帯域値算出手段１３は、加速度波形抽出手段１２で抽出された加速度波形の踏み込み前領域の波形から、予め設定した特定周波数帯域の振動レベルである踏み込み前帯域値Ｐを算出する。
図３（ａ）は、加速度センサー１１Ｃで検出した径方向加速度波形の一例を示す図で、横軸は時間[sec.]、縦軸は加速度の大きさ［G］である。微分加速度波形では、同図の左側の丸印に示す踏み込み端Ｅfと右側の丸印に示す蹴り出し端Ｅkの２つの接地端において加速度の大きさが０となる。
踏み込み前帯域値Ｐは、加速度波形のうちの同図の一点鎖線で囲った、踏み込み端Ｅfよりも前の所定の時間領域（踏み込み前領域）の加速度波形を抽出し、この抽出された加速度波形にバンドパスフィルタ（５０Ｈｚ〜１０００Ｈｚ）をかけて取出した波形のＲＭＳ平均をとることで得られる。
なお、踏み込み端Ｅfの位置及び蹴り出し端Ｅkの位置については、図３（ａ）に示す加速度波形のゼロクロス点から求めるよりは、図３（ｂ）に示す微分加速度波形のピークの位置から求める方が精度が高い。 The acceleration waveform extracting means 12 is used when the tire radial acceleration in the vicinity of the tire contact surface in the center portion 4 from the signal representing the magnitude of the tire radial acceleration acting on the center portion 4 of the tire tread 3 output from the acceleration sensor 11. A tire radial acceleration waveform (hereinafter referred to as an acceleration waveform), which is a series waveform, is extracted. The acceleration waveform does not necessarily have to be a waveform for one round of the tire, and may be, for example, about 60% of the length of one cycle as long as the waveform in the vicinity of the ground contact surface is included.
The band value calculating unit 13 calculates a pre-stepping band value P that is a vibration level in a specific frequency band set in advance from the waveform in the region before the stepping of the acceleration waveform extracted by the acceleration waveform extracting unit 12.
FIG. 3A shows an example of a radial acceleration waveform detected by the acceleration sensor 11C, where the horizontal axis represents time [sec.] And the vertical axis represents acceleration magnitude [G]. In the differential acceleration waveform, the magnitude of acceleration is zero at the two ground contact ends, that is, the stepping end E f indicated by the left circle in the figure and the kicking end E k indicated by the right circle.
The pre-depression band value P is obtained by extracting an acceleration waveform in a predetermined time region (pre-depression region) before the depressing end E f surrounded by a one-dot chain line in the figure of the acceleration waveform. It is obtained by taking the RMS average of the waveform extracted by applying a band pass filter (50 Hz to 1000 Hz) to the waveform.
Note that the position of the stepping end E f and the position of the kicking end E k are not obtained from the zero cross point of the acceleration waveform shown in FIG. 3A, but the peak position of the differential acceleration waveform shown in FIG. It is more accurate to calculate from

微分加速度波形演算手段１４は、加速度波形抽出手段１２で抽出された加速度波形を時間微分して微分加速度波形を求める。
微分ピーク値算出手段１５は、微分加速度波形から微分加速度波形の接地端部に出現するピークの大きさである微分ピーク値Ｖを算出する。
図３（ｂ）は、前記の図３（ａ）に示した加速度波形を微分して得られた微分加速度波形で、横軸は時間［sec.］、縦軸は微分加速度の大きさ[G/sec.]である。
以下、微分加速度波形に出現する２つの接地端Ｅf，Ｅkにおける微分加速度の大きさを微分ピーク値Ｖという。
本例では、微分ピーク値Ｖとして、２つの接地端Ｅf，Ｅkのうち、踏み込み端Ｅfにおける微分ピーク値を用いたが、蹴り出し端Ｅkの微分ピーク値を用いてもよいし、踏み込み端Ｅfの微分ピーク値と蹴り出し端Ｅkの微分ピーク値との平均（絶対値の平均）を用いてもよい。 The differential acceleration waveform calculation means 14 obtains a differential acceleration waveform by time differentiation of the acceleration waveform extracted by the acceleration waveform extraction means 12.
The differential peak value calculation means 15 calculates a differential peak value V that is the magnitude of a peak that appears at the grounded end of the differential acceleration waveform from the differential acceleration waveform.
3B is a differential acceleration waveform obtained by differentiating the acceleration waveform shown in FIG. 3A. The horizontal axis is time [sec.], And the vertical axis is the magnitude of differential acceleration [G. / sec.].
Hereinafter, the magnitude of the differential acceleration at the two grounded ends E f and E k appearing in the differential acceleration waveform is referred to as a differential peak value V.
In this example, as the differential peak value V, the differential peak value at the stepping-in end E f out of the two grounding ends E f and E k is used, but the differential peak value at the kick-out end E k may be used. The average (average of absolute values) of the differential peak value at the stepping-in end E f and the differential peak value at the kicking-out end E k may be used.

微分ピーク平均値算出手段１６は、微分ピーク値算出手段１５で算出された微分ピーク値Ｖを踏み込み前帯域値Ｐ毎に計数する計数部１６ａと微分ピーク値の平均値である微分ピーク平均値を算出する平均値算出部１６ｂとを備える。
微分ピーク値Ｖは踏み込み前帯域値Ｐ毎に得られるが、計数部１６ａでは、微分ピーク値Ｖの数を計数する際に、踏み込み前帯域値Ｐを所定のレベル幅Δを有する離散的な踏み込み前帯域値Ｐiとし、この離散的な踏み込み前帯域値Ｐiを中心にした［Ｐi−Δ/２，Ｐi＋Δ/２］の領域内に入るＰに対応する微分ピーク値を踏み込み前帯域値Ｐiに対応する微分ピーク値Ｖiとして計数する。
平均値算出部１６ｂでは、計数された微分ピーク値Ｖiが予め設定された個数であるＮ個に達したときに、微分ピーク値Ｖiの平均値である微分ピーク平均値Ｖi-aveを算出する。微分ピーク平均値Ｖi-aveは踏み込み前帯域値Ｐi毎にそれぞれ算出する。 The differential peak average value calculation means 16 counts the differential peak value V calculated by the differential peak value calculation means 15 and counts the differential peak average value, which is the average value of the differential peak values, and a counting unit 16a that counts for each pre-band value P. And an average value calculating unit 16b for calculating.
The differential peak value V is obtained for each pre-depression band value P. When the counting unit 16a counts the number of differential peak values V, the pre-depression band value P is discretely depressed with a predetermined level width Δ. The front band value P i is set, and the differential peak value corresponding to P that falls within the region of [P i −Δ / 2, P i + Δ / 2] centered on the discrete pre-step-in band value P i is before stepping on. The differential peak value V i corresponding to the band value P i is counted.
In the average value calculating unit 16b, when the counted differentiated peak value V i reaches N number is the number that is set in advance, the differential peak average value V i-ave is the average value of the differential peak value V i calculate. The differential peak average value V i-ave is calculated for each pre - depression band value P i .

基準微分ピーク値算出手段１７は、近似線作成部１７ａと基準微分ピーク値算出部１７ｂとを備える。
近似線作成部１７ａは、横軸を踏み込み前帯域値Ｐi、縦軸を微分ピーク平均値Ｖi-aveとして踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとをプロットしたグラフを作成し、踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係を表す近似線を求める。
基準微分ピーク値算出部１７ｂでは、前記のグラフに近似線を書き込むとともに、予め設定された基準踏み込み前帯域値Ｐkに対応する近似線上の微分ピーク平均値Ｖkを算出し、このＶkを基準微分ピーク値Ｖkとしてタイヤ摩耗量推定手段１９に出力する。
記憶手段１８は、予め求めておいた基準微分ピーク値Ｖkとタイヤの摩耗量Ｍとの関係を示すＶ−Ｍマップ１８Ｍを記憶する。
タイヤ摩耗量推定手段１９では、基準微分ピーク値算出手段１７で算出された基準微分ピーク値Ｖkと記憶手段１８に記憶されたＶ−Ｍマップ１８Ｍとから、当該タイヤ１の摩耗量を推定する。 The reference differential peak value calculation means 17 includes an approximate line creation unit 17a and a reference differential peak value calculation unit 17b.
The approximate line creation unit 17a plots the pre-depression band value P i and the differential peak average value V i-ave with the horizontal axis representing the pre-depression band value P i and the vertical axis representing the differential peak average value V i-ave. create, obtaining an approximate line representing the relationship between the depression before the bandwidth values P i and the differential peak average value V i-ave.
The reference differential peak value calculation unit 17b writes an approximate line to the graph, calculates a differential peak average value V k on the approximate line corresponding to a preset reference step-down band value P k , and calculates this V k . The reference differential peak value V k is output to the tire wear amount estimating means 19.
Storage means 18 stores the V-M map 18M showing the relationship between the reference differential peak value V k and wear amount M of the tire obtained in advance.
The tire wear amount estimating means 19 estimates the wear amount of the tire 1 from the reference differential peak value V k calculated by the reference differential peak value calculating means 17 and the VM map 18M stored in the storage means 18. .

次に、タイヤ摩耗量推定方法について、図４のフローチャートを参照して説明する。
まず、加速度センサー１１により、タイヤトレッド３の変形に伴って変形するインナーライナー部２内面におけるタイヤ径方向加速度を検出して増幅した後、これら検出されたタイヤ径方向加速度をインナーライナー部２に設置された送信器１１Ｆから車体側に配置された記憶・演算部１０Ｂに送信する（ステップＳ１０）。
記憶・演算部１０Ｂでは、加速度センサー１１から連続して出力されるタイヤトレッド３に作用するタイヤ径方向加速度の大きさを表す信号から加速度波形を抽出する（ステップＳ１１）とともに、加速度波形を時間微分して微分加速度波形を微分演算により求める（ステップＳ１２）。
次に、ステップＳ１２で抽出された加速度波形の踏み込み前領域の波形から、予め設定した特定周波数帯域の振動レベルである踏み込み前帯域値Ｐを算出する（ステップＳ１３）とともに、微分加速度波形から踏み込み端側のピーク値である微分ピーク値Ｖを算出する。 Next, a tire wear amount estimation method will be described with reference to the flowchart of FIG.
First, the acceleration sensor 11 detects and amplifies the tire radial acceleration on the inner surface of the inner liner portion 2 that is deformed as the tire tread 3 is deformed, and then installs the detected tire radial acceleration on the inner liner portion 2. Transmitted from the transmitter 11F thus transmitted to the storage / calculation unit 10B arranged on the vehicle body side (step S10).
The storage / calculation unit 10B extracts an acceleration waveform from a signal representing the magnitude of the tire radial acceleration acting on the tire tread 3 continuously output from the acceleration sensor 11 (step S11), and time-differentiates the acceleration waveform. Then, the differential acceleration waveform is obtained by differential calculation (step S12).
Next, a pre-depression band value P, which is a vibration level in a specific frequency band set in advance, is calculated from the waveform in the pre-depression region of the acceleration waveform extracted in step S12 (step S13), and the depressing end is determined from the differential acceleration waveform. A differential peak value V which is a peak value on the side is calculated.

次に、微分ピーク値Ｖを踏み込み前帯域値Ｐ毎に計数する（ステップＳ１４）。
図５（ａ）に示すように、横軸を踏み込み前帯域値Ｐ、縦軸を微分ピーク値Ｖとしたグラフを作成すると、踏み込み前帯域値Ｐiを中心にしたレベル幅がΔの領域、すなわち、領域［Ｐi−Δ/２，Ｐi＋Δ/２］内に入る微分ピーク値Ｖiの数は踏み込み前帯域値Ｐiにより異なる。そこで、本例では、図５（ｂ）に示すように、各領域内に入る微分ピーク値の数を揃えるため、横軸を踏み込み前帯域値Ｐi、縦軸を各領域［Ｐi−Δ/２，Ｐi＋Δ/２］内に入る微分ピーク値Ｖiとしたヒストグラムを作成して、各領域［Ｐi−Δ/２，Ｐi＋Δ/２］内に入る微分ピーク値Ｖiの数をカウントする（但し、ｉ＝１〜ｍ；ｍは踏み込み前帯域値Ｐの分割数）。
ステップＳ１５では、領域［Ｐi−Δ/２，Ｐi＋Δ/２］内に入る微分ピーク値の数ｎがＮ個に達したかどうかを各領域［Ｐi−Δ/２，Ｐi＋Δ/２］毎に判定し、Ｎ個に達した領域［Ｐi−Δ/２，Ｐi＋Δ/２］がある場合には、図５（ｃ）に示すように、当該領域［Ｐi−Δ/２，Ｐi＋Δ/２］におけるＮ個の微分ピーク値Ｖiの平均値である微分ピーク平均値Ｖi-aveを算出する。 Next, the differential peak value V is counted for each pre-band value P (step S14).
As shown in FIG. 5A, when a graph with the horizontal axis representing the pre-depression band value P and the vertical axis representing the differential peak value V is created, the level width centered on the pre-depression band value P i is Δ, That is, the number of differential peak values V i falling within the region [P i −Δ / 2, P i + Δ / 2] differs depending on the pre-step-in band value P i . Therefore, in this example, as shown in FIG. 5B, in order to equalize the number of differential peak values that fall within each region, the horizontal axis is stepped on before the band value P i , and the vertical axis is each region [P i −Δ. / 2, P i + Δ / 2] is created as a differential peak value V i that falls within the range [P i −Δ / 2, P i + Δ / 2], and the differential peak value V i that falls within each region [P i −Δ / 2] The number is counted (where i = 1 to m; m is the number of divisions of the pre-step-in band value P).
In step S15, whether or not the number n of differential peak values that fall within the region [P i −Δ / 2, P i + Δ / 2] reaches N is determined for each region [P i −Δ / 2, P i + Δ. / 2] and when there are N [P i −Δ / 2, P i + Δ / 2], the area [P i − A differential peak average value V i-ave that is an average value of N differential peak values V i in Δ / 2, P i + Δ / 2] is calculated.

一方、領域内に入る微分ピーク値の数が予め設定した数Ｎになっていない領域［Ｐj−Δ/２，Ｐj＋Δ/２］がある場合には、ステップＳ１１に戻って、加速度波形の抽出を継続する。
すなわち、本例では、微分ピーク値Ｖiの平均を求める際に、微分ピーク値Ｖiを踏み込み前帯域値Ｐi毎に計数し、計数された踏み込み前帯域値Ｐi毎の微分ピーク値Ｖiの数がそれぞれ予め設定された個数であるＮ個に全て達するまで、ステップＳ１１〜ステップＳ１４までの操作を繰り返し、全ての踏み込み前帯域値Ｐiについて微分ピーク平均値Ｖi-aveを計算する。
なお、微分ピーク平均値Ｖi-aveの算出は、各領域［Ｐi−Δ/２，Ｐi＋Δ/２］において微分ピーク値Ｖiの数が全てＮ個になってから行ってもよい。 On the other hand, if there is a region [P j −Δ / 2, P j + Δ / 2] where the number of differential peak values falling within the region is not the preset number N, the process returns to step S11 to return to the acceleration waveform. Continue extraction.
That is, in this example, when determining the average of the differential peak value V i, counted before each band value P i depress the differential peak value V i, counted depression before the bandwidth values P i for each of the differential peak value V The operations from step S11 to step S14 are repeated until the number of i reaches the preset number N, and the differential peak average value V i-ave is calculated for all the pre-stepping band values P i. .
The differential peak average value V i-ave may be calculated after the number of differential peak values V i has become N in each region [P i −Δ / 2, P i + Δ / 2]. .

全ての領域［Ｐi−Δ/２，Ｐi＋Δ/２］において微分ピーク平均値Ｖi-aveの計算が終了した後には、ステップＳ１６に進んで、踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係を表す近似線を求める。近似線の求め方としては、例えば、図６（ａ）に示すように、周知の最小自乗法などを用いて踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの一次回帰線を求めてこれを近似線とすればよい。
そして、図６（ｂ）に示すように、予め設定された基準踏み込み前帯域値Ｐkに対応する近似線上の微分ピーク平均値を求めてこれを基準微分ピーク値Ｖkとする（ステップＳ１７）。
最後に、算出された基準微分ピーク値Ｖkと記憶手段１８に記憶されたＶ−Ｍマップ１８Ｍとから、当該タイヤ１の摩耗量を推定する（ステップＳ１８）。
なお、Ｖ−Ｍマップ１８Ｍは、加速度センサーを搭載して新品タイヤ及び複数の異なる摩耗状態を有するタイヤを試験タイヤとし、これらの試験タイヤを搭載した車両を様々な路面状態の路面で走行させ、前記ステップＳ１０〜ステップＳ１８までの操作を行って各試験タイヤにおける基準微分ピーク値Ｖkを求めることで作成できる。 After the calculation of the differential peak average value V i-ave is completed in all the regions [P i −Δ / 2, P i + Δ / 2], the process proceeds to step S16, where the pre-step-in band value P i and the differential peak average are calculated. An approximate line representing the relationship with the value V i-ave is obtained. As a method of obtaining the approximate line, for example, as shown in FIG. 6A , a linear regression line between the pre-step-in band value P i and the differential peak average value V i-ave using a known least square method or the like is used. What is necessary is just to obtain and use this as an approximate line.
Then, as shown in FIG. 6 (b), a differential peak average value on an approximate line corresponding to a preset reference step-down band value P k is obtained and set as a reference differential peak value V k (step S17). .
Finally, the wear amount of the tire 1 is estimated from the calculated reference differential peak value V k and the VM map 18M stored in the storage means 18 (step S18).
The VM map 18M has a new tire and a plurality of tires having different wear states as test tires mounted with an acceleration sensor, and a vehicle on which these test tires are mounted travels on various road surface conditions. It can be created by calculating the reference differential peak value V k in each test tire by performing the operations from step S10 to step S18.

このように、本実施の形態では、タイヤ径方向加速度波形の踏み込み前領域の波形から算出した踏み込み前の振動レベルの大きさである踏み込み前帯域値Ｐと、タイヤ径方向加速度波形を微分して得られた微分加速度波形の接地端部に出現するピークの大きさである微分ピーク値Ｖとを算出する操作を、所定幅を有する踏み込み前帯域値Ｐiに対応する微分ピーク値Ｖiの算出回数がＮ回になるまで複数回繰り返して、微分ピーク値Ｖiの平均である微分ピーク平均値Ｖi-aveを算出した後、踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係を示す近似線を求め、この近似線から予め設定された基準踏み込み前帯域値Ｐkに対応する微分ピーク値である基準微分ピーク値Ｖkを算出し、この基準微分ピーク値Ｖkと、予め求めておいた基準微分ピーク値とタイヤの摩耗量との関係を示すＶ−Ｍマップ１８Ｍとから当該タイヤの摩耗量を推定するようにしたので、路面の凹凸度合いである路面粗さにより異なる踏み込み前帯域値と微分ピーク値の関係を考慮したタイヤの摩耗量の推定を行うことができる。したがって、路面の状態等による踏み込み前帯域値のバラつきによる影響を低減することができるだけでなく、微分ピーク値のバラつきによる影響についても低減することができるので、タイヤの摩耗量の推定精度を向上させることができる。
なお、単に平均値を用いただけでは、踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係が前述した近似線からずれてしまい、路面粗さによる誤差が生じるので、タイヤの摩耗の度合いの推定精度を十分に高めることは困難である。 As described above, in the present embodiment, the pre-depression band value P that is the magnitude of the vibration level before depressing calculated from the waveform of the pre-depression region of the tire radial acceleration waveform and the tire radial acceleration waveform are differentiated. The operation of calculating the differential peak value V which is the magnitude of the peak appearing at the grounded end of the obtained differential acceleration waveform is calculated as the differential peak value V i corresponding to the pre-step-in band value P i having a predetermined width. After calculating the differential peak average value V i-ave , which is the average of the differential peak values V i , repeatedly until the number of times reaches N times, the pre-step-in band value P i and the differential peak average value V i-ave We obtain an approximate line indicating the relationship to calculate the reference differential peak value V k is a preset reference depression before differential peak value corresponding to the band value P k from the approximate line, and the reference differential peak value V k Standards that have been obtained in advance Since the wear amount of the tire is estimated from the VM map 18M showing the relationship between the minute peak value and the wear amount of the tire, the pre-stepping zone value and the differential which differ depending on the road surface roughness which is the degree of unevenness of the road surface The amount of tire wear can be estimated in consideration of the relationship between peak values. Accordingly, not only can the influence due to the variation in the pre-depression band value due to the road surface condition etc. be reduced, but also the influence due to the variation in the differential peak value can be reduced, so that the estimation accuracy of the tire wear amount is improved. be able to.
Note that simply using the average value, deviates from the approximate line relationship between depression before the bandwidth values P i and the differential peak average value V i-ave is described above, since the error due to the road surface roughness occurs, the wear of the tire It is difficult to sufficiently increase the accuracy of estimation of the degree of.

なお、前記実施の形態では、踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係を表す近似線を用いた基準微分ピーク値Ｖkを求めたが、例えば、Ｖi-ave＝ａ・Ｐi＋ｂのような近似式を求め、この近似式から基準微分ピーク値Ｖkを求めてもよい。
また、前記例では、踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係から近似線もしくは近似式を求めたが、図５（ａ）に示すグラフから直接近似線もしくは近似式を求めてもよい。この場合には、前記実施の形態よりもタイヤ摩耗量の推定精度は低下するが、近似線もしくは近似式を用いて求めた基準微分ピーク値Ｖkからタイヤ摩耗量を推定しているので、単に踏み込み前帯域値Ｐの平均と微分ピーク値Ｖの平均値とからタイヤ摩耗量を推定した場合よりも推定精度を高めることができる。
また、前記例では、基準微分ピーク値ＶkとＶ−Ｍマップ１８Ｍとから当該タイヤの摩耗量を推定したが、基準微分ピーク値Ｖkに対して閾値Ｋjを設定し、閾値Ｋjと基準微分ピーク値Ｖkとを比較してタイヤ摩耗量を推定してもよい。
例えば、Ｋ1＜Ｋ2＜Ｋ3とし、新品タイヤの溝深さを１５ｍｍとしたとき、Ｖk＜Ｋ1なら摩耗量が３ｍｍ未満、Ｋ1≦Ｖk＜Ｋ2なら３ｍｍ以上６ｍｍ未満、Ｋ2≦Ｖk＜Ｋ3なら６ｍｍ以上９ｍｍ未満、Ｖk≧Ｋ3なら９ｍｍ以上であると判定すればよい。 In the above embodiment, the reference differential peak value V k using the approximate line representing the relationship between the pre-step-in band value P i and the differential peak average value V i-ave is obtained. For example, V i-ave An approximate expression such as = a · P i + b may be obtained, and the reference differential peak value V k may be obtained from this approximate expression.
In the above example, the relationship between the depression before the bandwidth values P i and the differential peak average value V i-ave calculated approximate line or approximate expression shown in FIG. 5 (a) directly fitted line or approximation formula from the graph You may ask for. In this case, the estimation accuracy of the tire wear amount is lower than that in the above embodiment, but since the tire wear amount is estimated from the reference differential peak value V k obtained using the approximate line or the approximate expression, The estimation accuracy can be increased as compared with the case where the tire wear amount is estimated from the average of the pre-depression band value P and the average value of the differential peak value V.
In the above example, the tire wear amount is estimated from the reference differential peak value V k and the VM map 18M. However, a threshold K j is set for the reference differential peak value V k , and the threshold K j The tire wear amount may be estimated by comparing with the reference differential peak value V k .
For example, when K 1 <K 2 <K 3 and the groove depth of a new tire is 15 mm, if V k <K 1, the wear amount is less than 3 mm, and if K 1 ≦ V k <K 2, 3 mm or more and less than 6 mm, If K 2 ≦ V k <K 3, it may be determined that it is 6 mm or more and less than 9 mm, and if V k ≧ K 3, it is determined that it is 9 mm or more.

また、前記例では、加速度センサー１１をタイヤ１のインナーライナー部２のタイヤ幅方向中心に１個設けたが、なお、加速度センサー１１を複数個設けてもよい。特に、タイヤトレッド３のタイヤ幅方向中心に溝部が形成されているタイヤでは、インナーライナー部２のタイヤ幅方向中心から左右対称の位置にある陸部のタイヤ径方向内側に設け、右側の加速度センサーで検出した加速度波形から推定したタイヤ摩耗量と左側の加速度センサーで検出した加速度波形から推定したタイヤ摩耗量とから、タイヤの摩耗状態を推定することが好ましい。なお、加速度センサー１１を複数個設ける場合には、Ｖ−Ｍマップ１８Ｍについても、加速度センサー１１の設置箇所に応じて複数準備することが好ましい。
また、前記例では、踏み込み前帯域値Ｐiを踏み込み前領域の加速度波形にバンドパスフィルタ（５０Ｈｚ〜１０００Ｈｚ）をかけ、ＲＭＳ平均をとることで求めたが、踏み込み前領域の加速度波形をＦＦＴ処理して周波数帯域が５０Ｈｚ〜１０００Ｈｚの周波数成分の大きさを求め、この周波数成分の大きさを踏み込み前帯域値としてもよい。 In the above example, one acceleration sensor 11 is provided at the center of the inner liner portion 2 of the tire 1 in the tire width direction. However, a plurality of acceleration sensors 11 may be provided. In particular, in a tire in which a groove is formed at the center of the tire tread 3 in the tire width direction, the right acceleration sensor is provided on the inner side in the tire radial direction of the land portion that is symmetrical to the center of the inner liner 2 in the tire width direction. It is preferable to estimate the tire wear state from the tire wear amount estimated from the acceleration waveform detected in step 1 and the tire wear amount estimated from the acceleration waveform detected by the left acceleration sensor. When a plurality of acceleration sensors 11 are provided, it is preferable to prepare a plurality of VM maps 18M according to the location where the acceleration sensor 11 is installed.
In the above example, the band value before the depression P i is obtained by applying the bandpass filter (50 Hz to 1000 Hz) to the acceleration waveform in the area before depression and taking the RMS average, but the acceleration waveform in the area before depression is FFT processed. Then, the magnitude of the frequency component having a frequency band of 50 Hz to 1000 Hz may be obtained, and the magnitude of this frequency component may be set as the pre-band value.

［実施例］
本発明によるタイヤ摩耗量推定装置を取付けた試験タイヤを搭載した試験車両を、車速40〜80km/hrにて、様々な路面状態の路面を走行させたときの踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係を調べた結果を図７に示す。
なお、踏み込み前帯域値Ｐi及び微分ピーク平均値Ｖi-aveの値は測定値ではなく換算値［a.u.］を用いた。すなわち、踏み込み前帯域値Ｐi、及び微分ピーク平均値Ｖi-aveは車速（タイヤ回転時間）に応じて変化するので、踏み込み前帯域値Ｐiにはタイヤ回転時間を乗じ、微分ピーク平均値Ｖi-aveにはタイヤ回転時間の３乗をそれぞれ乗じることで換算を行った。
試験タイヤのタイヤサイズは315/70R22.5である。
また、試験タイヤの種類は、新品タイヤ（残溝 15mm）、残溝 9mmのタイヤ、残溝 6mmのタイヤ、残溝 3mmのタイヤの４種である。
図７に示すように、微分ピーク平均値Ｖi-aveは踏み込み前帯域値Ｐiが増加するにつれて減少し、その傾きの大きさ（絶対値）はタイヤ摩耗量が大きいほど大きいことが分かる。したがって、加速度センサーを用いて検出したタイヤ径方向加速度から踏み込み前帯域値Ｐiと微分ピーク平均値Ｖi-aveとの関係を示す近似線もしくは近似式が求めることができることが確認された。
また、図８は、踏み込み前帯域値がＰk＝２．５のときの微分ピーク平均値である基準微分ピーク平均値Ｖk-aveとタイヤ摩耗量を表すパラメータの１つである実際のタイヤの残溝量［mm］との関係を調べた結果を示す図である。同図に示すように、タイヤ摩耗量の対応する数値であるタイヤの残溝量［mm］と基準微分ピーク平均値Ｖk-aveとは高い相関を有するので、基準微分ピーク平均値Ｖk-aveを求めることで、当該タイヤの摩耗量を精度よく推定できることが確認された。 [Example]
The test vehicle equipped with a test tire mounted tire wear amount estimating apparatus according to the present invention, the depression before the bandwidth values P i and the differential peak when at speed 40~80km / hr, was run on a road surface of different road surface conditions The result of examining the relationship with the average value V i-ave is shown in FIG.
Note that the pre-depression band value P i and the differential peak average value V i-ave are not measured values but converted values [au]. That is, since the pre-depression band value P i and the differential peak average value V i-ave change according to the vehicle speed (tire rotation time), the pre-depression band value P i is multiplied by the tire rotation time to obtain the differential peak average value. Conversion was performed by multiplying V i-ave by the cube of the tire rotation time.
The tire size of the test tire is 315 / 70R22.5.
There are four types of test tires: new tires (15 mm remaining groove), tires with 9 mm remaining grooves, tires with 6 mm remaining grooves, and tires with 3 mm remaining grooves.
As shown in FIG. 7, it can be seen that the differential peak average value V i-ave decreases as the pre - depression band value P i increases, and the magnitude (absolute value) of the slope increases as the tire wear amount increases. Therefore, it was confirmed that it is possible to approximate line or approximate expression indicating the relationship between the radial acceleration detected with depression before the bandwidth values P i and the differential peak average value V i-ave is obtained by using an acceleration sensor.
FIG. 8 shows a reference differential peak average value V k-ave , which is a differential peak average value when the pre-depression band value is P k = 2.5, and an actual tire which is one of parameters representing tire wear. It is a figure which shows the result of having investigated the relationship with the amount of remaining grooves [mm]. As shown in the figure, the tire residual groove amount [mm], which is a numerical value corresponding to the tire wear amount, and the reference differential peak average value V k-ave have a high correlation, so the reference differential peak average value V k- It was confirmed that the wear amount of the tire can be accurately estimated by obtaining ave .

以上、本発明を実施の形態を用いて説明したが、本発明の技術的範囲は前記実施の形態に記載の範囲には限定されない。前記実施の形態に、多様な変更または改良を加えることが可能であることが当業者にも明らかである。そのような変更または改良を加えた形態も本発明の技術的範囲に含まれ得ることが、特許請求の範囲から明らかである。   As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

このように、本発明によれば、タイヤの摩耗状態をドライバーが感知する前に精度よくかつ安定して推定できる。したがって、タイヤの摩耗が進展している場合には、これをドライバーに警報すれば、ドライバーはタイヤを交換するなどの対策を的確に行うことができるので、車両の走行安全性を向上させることができる。   Thus, according to the present invention, it is possible to accurately and stably estimate the wear state of the tire before the driver senses it. Therefore, if the wear of the tire is progressing, if the driver is warned of this, the driver can take appropriate measures such as replacing the tire, so that the driving safety of the vehicle can be improved. it can.

１ タイヤ、２ インナーライナー部、３ タイヤトレッド、４ センター部、
５ ホイール、
１０ タイヤ摩耗量推定装置、１０Ａ センサー部、１０Ｂ 記憶・演算部、
１１ 加速度センサー、１１Ｆ 送信機、１２ 加速度波形抽出手段、
１３ 帯域値算出手段、１４ 微分加速度波形演算手段、１５ 微分ピーク値算出手段、１６ 微分ピーク平均値算出手段、１６ａ 計数部、１６ｂ 平均値算出部、
１７ 基準微分ピーク値算出手段、１７ａ 近似線作成部、
１７ｂ 基準微分ピーク値算出部、１８ 記憶手段、１９ タイヤ摩耗量推定手段。 1 tire, 2 inner liner part, 3 tire tread, 4 center part,
5 wheels,
10 tire wear amount estimation device, 10A sensor unit, 10B storage / calculation unit,
11 acceleration sensor, 11F transmitter, 12 acceleration waveform extraction means,
13 band value calculation means, 14 differential acceleration waveform calculation means, 15 differential peak value calculation means, 16 differential peak average value calculation means, 16a counting unit, 16b average value calculation unit,
17 reference differential peak value calculation means, 17a approximate line creation unit,
17b Reference differential peak value calculation unit, 18 storage means, 19 tire wear amount estimation means.

Claims (3)

加速度センサーを用いて検出したタイヤ径方向加速度からタイヤのトレッドの摩耗量を推定するタイヤ摩耗量推定方法であって、
タイヤトレッドの内面に配置された加速度センサーを用いて当該タイヤのタイヤ径方向加速度を検出するステップ（ａ）と、
前記検出されたタイヤ径方向加速度から接地面近傍を含むタイヤ径方向加速度波形を抽出するステップ（ｂ）と、
前記タイヤ径方向加速度波形の踏み込み前領域の波形から、予め設定した特定周波数帯域の振動レベルである踏み込み前帯域値を算出するステップ（ｃ）と、
前記タイヤ径方向加速度波形を微分して微分加速度波形を求めるステップ（ｄ）と、
前記微分加速度波形から当該微分加速度波形の接地端部に出現するピークの大きさである微分ピーク値を算出するステップ（ｅ）と、
前記ステップ（ａ）〜（ｅ）を複数回繰り返して、複数の互いに異なる踏み込み前帯域値のそれぞれについて、前記微分ピーク値を算出するステップ（ｆ）と、
前記ステップ（ｆ）で算出された複数の踏み込み前帯域値と微分ピーク値とから、前記踏み込み前帯域値と前記微分ピーク値との関係を示す近似式、もしくは、前記踏み込み前帯域値に対する前記微分ピーク値をプロットして得られる近似線を求めるステップ（ｇ）と、
前記近似式もしくは近似線から予め設定された基準踏み込み前帯域値に対応する微分ピーク値である基準微分ピーク値を算出するステップ（ｈ）と、
前記算出された基準微分ピーク値から当該タイヤの摩耗量を推定するステップ（ｉ）と、を備えることを特徴とするタイヤ摩耗量推定方法。 A tire wear amount estimation method for estimating a wear amount of a tire tread from a tire radial acceleration detected using an acceleration sensor,
(A) detecting the tire radial acceleration of the tire using an acceleration sensor disposed on the inner surface of the tire tread;
Extracting a tire radial acceleration waveform including the vicinity of the contact surface from the detected tire radial acceleration (b);
Calculating a pre-depression band value that is a vibration level in a specific frequency band set in advance from the waveform of the pre-depression region of the tire radial direction acceleration waveform;
Differentiating the tire radial acceleration waveform to obtain a differential acceleration waveform (d);
A step (e) of calculating a differential peak value which is a size of a peak appearing at a grounded end portion of the differential acceleration waveform from the differential acceleration waveform;
Said step (a) ~ (e) repeated multiple times, for each of a plurality of different depression before the bandwidth values, and step (f) to calculate the differential peak value,
From the plurality of pre-depression band values and differential peak values calculated in step (f), an approximate expression indicating the relationship between the pre-depression band value and the differential peak value, or the differential with respect to the pre-depression band value Obtaining an approximate line obtained by plotting the peak value (g);
A step (h) of calculating a reference differential peak value that is a differential peak value corresponding to a preset reference step-in band value from the approximate expression or the approximate line;
And (i) estimating the amount of wear of the tire from the calculated reference differential peak value. 前記ステップ（ｆ）では、
前記微分ピーク値を前記踏み込み前帯域値毎に計数し、前記計数された踏み込み前帯域値毎の微分ピーク値の数が予め設定された個数であるＮ個に全て達するまで、前記踏み込み前帯域値と前記微分ピーク値と算出する操作を繰り返し、
前記ステップ（ｇ）では、
前記踏み込み前帯域値毎に求められたＮ個の微分ピーク値の平均値である微分ピーク平均値を前記踏み込み前帯域値毎に算出した後、前記踏み込み前帯域値と微分ピーク平均値との関係を示す近似式、もしくは、前記踏み込み前帯域値に対する微分ピーク平均値をプロットして得られる近似線を求め、
前記ステップ（ｈ）では、前記近似式もしくは近似線から予め設定された基準踏み込み前帯域値に対応する微分ピーク平均値を算出してこれを基準微分ピーク値とし、
前記ステップ（ｉ）では、
前記算出された基準微分ピーク値と、予め求めておいた基準微分ピーク値とタイヤの摩耗量との関係を示すマップとから当該タイヤの摩耗量を推定することを特徴とする請求項１に記載のタイヤ摩耗量推定方法。 In step (f),
The differential peak value is counted for each pre-depression band value, and the pre-depression band value until the number of differential peak values for each pre-depressed band value reaches N which is a preset number. And the operation of calculating with the differential peak value,
In step (g),
After calculating a differential peak average value, which is an average value of N differential peak values obtained for each band value before depression, for each band value before depression, a relationship between the band value before depression and the differential peak average value Or an approximate line obtained by plotting the differential peak average value against the pre-step-in band value,
In the step (h), a differential peak average value corresponding to a preset reference depression step band value is calculated from the approximate expression or approximate line, and this is used as a reference differential peak value,
In step (i),
The tire wear amount is estimated from the calculated reference differential peak value and a map indicating a relationship between a reference differential peak value obtained in advance and a tire wear amount. Tire wear estimation method. 加速度センサーを用いて検出したタイヤ径方向加速度からタイヤトレッドの摩耗量を推定するタイヤ摩耗量推定装置であって、
タイヤトレッドの内面側に配置されてタイヤ径方向加速度を検出する加速度センサーと、
前記加速度センサーの出力信号から、接地面近傍を含むタイヤ径方向加速度波形を抽出する加速度波形抽出手段と、
前記タイヤ径方向加速度波形の踏み込み前領域の波形から、予め設定した特定周波数帯域の振動レベルである踏み込み前帯域値を算出する帯域値算出手段と、
前記タイヤ径方向加速度波形を微分して微分加速度波形を求める微分演算手段と、
前記微分加速度波形における接地端部のピーク値である微分ピーク値を算出する微分ピーク値算出手段と、
前記微分ピーク値を踏み込み前帯域値毎に計数する計数手段と、
前記計数された微分ピーク値の数が予め設定された個数であるＮ個に達したときに、前記微分ピーク値の平均値である微分ピーク平均値を算出する微分ピーク平均値算出手段と、前記踏み込み前帯域値と微分ピーク平均値との関係を示す近似式、もしくは、前記踏み込み前帯域値に対する微分ピーク平均値をプロットして得られる近似線を求め、前記近似式もしくは近似線から予め設定された基準踏み込み前帯域値に対応する微分ピーク平均値である基準微分ピーク値を算出する基準微分ピーク値算出手段と、
予め求めておいた基準微分ピーク値とタイヤの摩耗量との関係を示すマップを記憶する記憶手段と、
前記算出された基準微分ピーク値と前記記憶されたマップとから、当該タイヤの摩耗量を推定する摩耗量推定手段と、
を備えることを特徴とするタイヤ摩耗量推定装置。 A tire wear amount estimation device that estimates a wear amount of a tire tread from a tire radial acceleration detected using an acceleration sensor,
An acceleration sensor that is arranged on the inner surface side of the tire tread and detects tire radial acceleration;
Acceleration waveform extraction means for extracting a tire radial acceleration waveform including the vicinity of the ground contact surface from the output signal of the acceleration sensor;
Band value calculation means for calculating a pre-depression band value that is a vibration level in a specific frequency band set in advance from the waveform of the pre-depression region of the tire radial direction acceleration waveform;
Differentiating means for differentiating the tire radial acceleration waveform to obtain a differential acceleration waveform;
Differential peak value calculating means for calculating a differential peak value that is a peak value of a ground end in the differential acceleration waveform;
Counting means for counting the differential peak value for each pre-band value,
Differential peak average value calculating means for calculating a differential peak average value that is an average value of the differential peak values when the number of counted differential peak values reaches a preset number N, and An approximate expression indicating the relationship between the pre-stepping band value and the differential peak average value, or an approximate line obtained by plotting the differential peak average value with respect to the pre-stepping band value is obtained, and is set in advance from the approximate expression or the approximate line. A reference differential peak value calculating means for calculating a reference differential peak value which is a differential peak average value corresponding to the reference step-down band value;
Storage means for storing a map indicating a relationship between a reference differential peak value obtained in advance and a wear amount of a tire;
Wear amount estimation means for estimating the wear amount of the tire from the calculated reference differential peak value and the stored map;
A tire wear amount estimation device comprising:
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