Bridgestone Corporation

Bridestone Corporation

Kabushiki Kaisha Bridgestone

Takeshi Masago

Kazuo Hayashi

A device for estimating a state of a road surface on which a tire is running, the device including: an acceleration sensorinstalled in the tire; an acceleration information acquiring meansthat acquires acceleration information input to the tire from an output of the acceleration sensor; a storage meansthat stores acceleration information of each road surface roughness set in advance; and a road surface state estimating meansthat compares the acquired acceleration information with the acceleration information of each road surface roughness stored in the storage meansso as to estimate the state of the road surface.

Road surface state estimation method and road surface state estimation device

A sensor case () with a sensor housed therein for obtaining information on a tire, including a lower side member () having a bottom surface () to be attached on an inner surface of the tire or to a base () for mounting the sensor case () on the inner surface of the tire, and an upper side member () protruding from a surface () opposite to the bottom surface () of the lower side member () to a side opposite to the bottom surface () and having a width smaller than a width of the lower side member (). A side surface () of the lower side member () is formed of a curved surface convex outwardly in a width direction, and a side surface () of the upper side member () and a top surface () of the upper side member (), which is a surface opposite to the bottom surface (), are connected by a curved surface () being in contact with the top surface ().

Sensor case

In order to provide a method and a device capable of precisely estimating a load acting on a tire with less sensors, a load estimation devicefor estimating the load acting on the tire is provided with: an acceleration sensor; an acceleration waveform detection meansthat detects an acceleration waveform in a tire radial direction on the basis of an output of the acceleration sensor; a differential acceleration waveform computing meansthat differentiates the acceleration waveform to obtain a differential acceleration waveform; a peak position detection meansthat detects a position of a peak on a leading edge side and a position of a peak on a trailing edge side appearing in the differential acceleration waveform; a ground contact time ratio calculation meansthat calculates a ground contact time and a rotation time on the basis of the peak positions and calculates a ground contact time ratio, which is a ratio between the calculated ground contact time and the rotation time; and a load estimation meansthat estimates the load acting on the tire on the basis of the calculated ground contact time ratio and a K-W mapM representing a relationship between the calculated ground contact time ratio stored in a storage meansand the load.

Tire load estimation method and tire load estimation device

A method and an apparatus configured to acquire, as acceleration information, a peak level awhich is a magnitude of a peak on a positive side or a negative side of an acceleration signal in a tire circumferential direction or a tire width direction detected by an acceleration sensor, or a peak interval bwhich is a time interval between peaks, or acquire the peak level aor the peak interval bof a differential acceleration signal in a tire radial direction obtained by differentiating the acceleration signal in the tire radial direction; calculate ratios P, Qof a difference between the acquired acceleration information a, band average values Aof the acceleration information to the average values; and determine that the acceleration sensor is detached from the inside of the tire when the calculated ratio P, Qexceeds a preset threshold value K, Kby multiple times successively.

Method for determining detachment of acceleration sensor and apparatus for determining detachment of acceleration sensor

A method and apparatus capable of estimating a tire wear amount even on snow-covered road surfaces accurately and reliably are provided. To that end, a differentiated acceleration waveform of a radial acceleration waveform of a tire is obtained, and an operation of calculating a leading-end differentiated peak value and a trailing-end differentiated peak value from the differentiated acceleration waveform is repeated a plurality of times. At the same time, a differentiated peak ratio, which is a ratio between the leading-end differentiated peak value and the trailing-end differentiated peak value, is calculated for each of the leading-end differentiated peak values and the trailing-end differentiated peak values obtained. Either one of the leading-end differentiated peak values and the trailing-end differentiated peak values, having a differentiated peak ratio within a lower limit range of 0.6 to 0.8 and an upper limit range of 1.0 to 1.2, or computed values of the leading-end differentiated peak values and the trailing-end differentiated peak values are extracted as the differentiated peak values for wear estimation. And the tire wear amount is estimated using the plurality of extracted differentiated peak values for wear estimation.

Tire wear amount estimating method and tire wear amount estimating apparatus

A method and an apparatus for estimating uneven wear in the tire shoulder with high accuracy using a fewer number of sensors are provided. An uneven tire wear estimating apparatus includes an acceleration sensor () disposed on an inner surface of a tire tread for measuring radial acceleration, an acceleration waveform extracting means () for extracting an acceleration waveform in a post-trailing-end domain from output signals of the acceleration sensor, means for calculating a vibration level &#x3b1; of an uneven wear measured band and a vibration level &#x3b2; of a reference band from the extracted acceleration waveform, an uneven wear determination index calculating means () for calculating an uneven wear determination index &#x3b3;, which is an index for determining au uneven wear, from the vibration level &#x3b1; and the vibration level &#x3b2;, and a determining means () for determining whether an uneven wear is occurring in an edge of the tire shoulder from the value of the uneven wear determination index &#x3b3;.

Method and apparatus for estimating uneven tire wear

A method for accurately determining internal failures, such as separations, of a tire without affecting tire behaviors. Radial acceleration signals of a tire during vehicular travel are detected by an acceleration sensor () attached to the inner surface of the tire at the axial center of the tread. A frequency analysis is performed on the radial acceleration signals to obtain a frequency spectrum. A band value Xis calculated of a specific frequency band [f, f] within the range of 100 Hz-400 Hz, which includes the frequency of the second lowest peak of the peaks appearing in the frequency spectrum. Then a check is made to see whether or not the difference between this band value Xand a predetermined band value Yof a normal tire exceeds a threshold value K. And when Y&#x2212;X&#x3e;K, it is determined that an internal failure, such as a separation, is present in the tire.

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Tokyo, Japan

Takeshi Masago