Nippondenso Co., Ltd.

Denso Corporation

Nippon Soken, Inc.

Toyota Jidosha Kabushiki Kaisha & Kabushiki Kaisha Toyota Chuo Kenkyusho

Yuuichi Inoue

Takaji Umeno

Hideki Ohashi

Nobuyoshi Onogi

Toshiharu Naito

Shusaku Fujimoto

Kenji Tomiita

Katsuhiro Asano

Motonori Tominaga

Takeyasu Taguchi

Hiroyoshi Kojima

Kenji Fujiwara

Hiroyuki Kawai

Yoshihiro Nishikawa

Hiromi Tokuda

Shinjiro Fukada

To accurately detect a resonance frequency of tire even in high speed range by which tire air pressure state of each wheel is known, a calculation processing unit to which detection signals of wheel speed and resonance frequencies of tire are inputted calculates a timewise change amount of a wheel speed deviation that is a difference between wheel speed ratios of front and rear wheels. Then, it makes corrections to remove the influence of timewise change amounts of resonance frequencies of front wheels from timewise change amounts of wheel speed deviations based on a relationship between the resonance frequency and the wheel speed deviation when air pressure of the tire is changed. The unit then converts the corrected timewise change amount of the rotational state into the timewise change amount of the resonance frequencies of the rear wheels based on the above-described relationship and the resonance frequencies of the rear wheels and the timewise change amounts of the resonance frequencies of the rear wheels which have been accurately detected before the vehicle speed exceeds an upper limit value.

Tire air pressure detecting device

In a tire air pressure estimation based upon vibration components extracted rom a vehicle wheel speed signal, when the vehicle is a driven vehicle wheel, the precision of estimation is improved by canceling the components of vibration due to the resonance of the drive system from the vibration components based upon which the estimation calculation is made. The vibration components due to the resonance of the drive system can be canceled by canceling those vibration components extracted from the vehicle wheel speed signal which are the same in the phase between left and right driven vehicle wheels. When the tire air pressure of one of a pair of left and right driven vehicle wheels is lower than that of the other, the lower tire air pressure is more correctly estimated. Therefore, the higher tire air pressure may be estimated according to the lower tire air pressure against the drive system resonance.

Device for estimating air pressure of tire from vibration components of

In a speed detecting apparatus for a rotating body, a correction coefficient is used to correct a detecting error in each of pulse signal periods representing speed data of the rotating body. The correction coefficient is updated so as to cancel an aberration of the corresponding pulse signal period caused by a nonstandard factor of the rotating body. Specifically, an average value of the pulse signal periods corresponding to one rotation of the rotating body is first derived, then a value indicative of a deviation between corresponding one of the pulse signal periods and the average value is derived, and further, an updating value is derived by adjusting a degree of influence of the deviation indicative value to the correction coefficient using a correction sensitivity coefficient. The correction coefficient is updated by adding the updating value to a last value of the correction coefficient.

Speed detecting apparatus for rotating body

It is an object of the present invention to detect a tire air pressure indirectly with high detection precision. A tire air pressure detecting device includes a speed sensor for outputting a signal corresponding to a rotational speed of a tire, and an electronic control unit which inputs the signal from the speed sensor and performs predetermined arithmetic operations on that signal. The electronic control unit calculates a wheel speed based on the output signal of the speed sensor, performs a frequency analysis for the calculated vehicle speed, and derives a resonance frequency corresponding to the unsprung mass in the vertical and longitudinal directions. The tire air pressure is then detected based on this resonance frequency.

Growing community of inventors

Tokai, Japan

Yuuichi Inoue