Patent ID: 7257997
Filing Date: 2007-08-21
Classification: B60T,G01N

Abstract:
1. A method of detecting a longitudinal force of a tire which detects the longitudinal force in a circumferential direction applied to the tire, comprising: at least one mark provided in the tire on one circumferential line around a tire axis; a first sensor fixed to a vehicle body and capable of sequentially detecting a passage of said mark rotating together with the tire; a second sensor capable of detecting a rotation angle θ of an axle; and a computing means for computing a longitudinal force applied to the tire on the basis of an information from said first and second sensors, wherein said computing means comprises: (1) storing an information of a rotation angle θr of the axle detected by said second sensor when receiving information of the passage signal from said first sensor according to the passage of said mark; (2) previously storing an information of a no-load rotation angle θo of the axle detected by said second sensor when receiving information of the passage signal from said first sensor according to the passage of said mark, as the tire rotates in a no-load state; (3) computing a tire warp angle αr corresponding to a difference (θo−θr) between said rotation angle θr and said no-load rotation angle θo; and (4) computing a longitudinal force Fr of a tire applied during the running from said warp angle αr using a a previously determined relational equation between the tire warp angle α and the longitudinal force F applied to the tire.