| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately evaluate on-ice braking performance by improving measuring precision of friction coefficient and slip ratio. <P>SOLUTION: Braking procedures comprise: first stepwise braking to decelerate the tire in a stepwise manner from an initial speed va to an intermediate speed vb at a first small deceleration rate Δv1; and second stepwise braking to decelerate the tire in a stepwise manner from the intermediate speed vb at a second big deceleration rate Δv2. At each deceleration step, the tire is forced to run at each step speed v for a running time between 40 seconds and 60 seconds. Evaluation procedures comprise: an averaging step to obtain an average friction coefficient μ0 and an average slip ratio S0 per deceleration step by averaging a friction coefficient μ and a slip ratio S which are obtained from a vertical load Fz, a longitudinal force Fx and a step speed v that are measured per each deceleration step during a period after a lapse of 30 seconds in the running time Δt; and an evaluation step to evaluate on-ice braking performance based on a μ0-S0 curve made by plotting the average friction coefficient μ0 and the average slip ratio S0. <P>COPYRIGHT: (C)2012,JPO&INPIT |
