Physical quantity estimating apparatus and tire state determining apparatus, and estimating method of same and determination method of same

#The disclosure of Japanese Patent Application No. 2002-109818 filed on Apr. 11, 2002, including the specification, drawings and abstract are incorporated herein by reference in its entirety.

#1. Field of Invention

#The invention relates to a physical quantity estimating apparatus and a tire state determining apparatus. More particularly, the invention relates to a physical quantity estimating apparatus capable of estimating a physical quantity relating to a tire radius, taking into consideration a tire torsional spring and a suspension longitudinal spring of an estimated ideal vehicle model, using a method for estimating a road surface friction coefficient (p) gradient based on a wheel speed difference between any two wheels, e.g., a rear wheel and a front wheel, and an acceleration and deceleration rate of a vehicle during acceleration and deceleration of the vehicle, and a tire state determining apparatus that determines a tire state such as a tire type using the physical quantity estimated by the physical quantity estimating apparatus, and a determination method of that tire state determining apparatus.

#The above-mentioned exemplary embodiment and other exemplary embodiments, objects, features, advantages, technical and industrial significance of this invention will be better understood by reading the following detailed description of the exemplary embodiments of the invention, when considered in connection with the accompanying drawings, in which:

#FIG. 1 is a block diagram showing one exemplary embodiment of the invention;

#FIG. 2A is a schematic diagram showing an ideal vehicle model that takes into consideration a tire torsional spring element and a suspension longitudinal spring element according to an exemplary embodiment of the invention;

#Hereinafter, an exemplary embodiment of the invention will be described with reference to the appended drawings. In this exemplary embodiment, a physical quantity estimating apparatus according to the invention has been applied to a tire state determining apparatus such as an apparatus that determines a tire type.

#As shown in FIG. 1, this exemplary embodiment is configured with an acceleration/deceleration sensor 10 that detects an acceleration and deceleration rate of a vehicle body, a wheel speed sensor 12 provided on each of the four wheels, which detects a rotation speed (i.e., wheel speed) of the wheel on which it is provided (only one wheel speed sensor is shown in the figure), a physical quantity estimating apparatus 14 (i.e., an estimating portion) as an estimating means, and a constant memory 16. The constant memory 16 stores known values and the like indicative of a distribution ratio of braking force and driving force to each wheel and a distribution ratio of a load on each wheel when the vehicle is stopped.

#Further, the physical quantity estimating apparatus 14 estimates the physical quantity according to a method described later, using the value of the distribution ratio of braking force and driving force to each wheel and the distribution ratio of the load on each wheel that has been corrected according to the detected acceleration and deceleration rate, based on the wheel speed difference between any two wheels during deceleration and acceleration of the vehicle, using a vehicle—wheel model.