Patent ID: 9199517
Filing Date: 2015-12-01
Classification: B60C

Abstract:
1. A tire air pressure monitor device that monitors air pressure in tires, the tire air pressure monitor device comprising: a tire air pressure sensor configured to be installed on wheels of the tires to detect the air pressure in the tires; a transmitter configured to be provided on each of the wheels to transmit via wireless signal the air pressure along with identification information inherent to the transmitter; a receiver configured to be provided on a vehicle body to receive the wireless signal; a rotation position calculation unit provided on the vehicle body to correspond to each of the wheels for detecting a rotation position of the wheel; and a wheel position determination unit that accumulates as rotation position data for the wheels, the rotation position of the wheels acquired a plurality of times when a wireless signal is transmitted including a certain identification information; and that determines wheel position corresponding to the rotation position data having a smallest degree of dispersion from among the rotation position data as the wheel position for the transmitter corresponding to the identification information, the wheel position determination unit converting the rotation position of each of the wheels to a vector with a start point at an origin of a two dimensional plane and an end point at a point on a circumference of a unit circle; calculates a scalar quantity of an average vector of vectors for the rotation position data as a dispersion characteristic value; and determines a highest value among the dispersion characteristic values has having the smallest degree of dispersion.