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US-12618736-B2 - Wheel-state obtaining system

US12618736B2US 12618736 B2US12618736 B2US 12618736B2US-12618736-B2

Abstract

A wheel-state obtaining system includes: air pressure sensors each provided for a corresponding one of a plurality of wheels to detect an air pressure of a tire of the wheel; and temperature sensors each provided for a corresponding one of the wheels to detect a temperature of an inside of a tire of the wheel; and a controller. The controller obtains a temperature conversion air pressure, which is the air pressure of each tire when the temperature is a set temperature, based on a detected air pressure and a detected temperature. When a reduction amount of the temperature conversion air pressure of one of the wheels is greater than a reduction amount of the temperature conversion air pressure of each of other wheels except the one of the wheels, the controller determines that the air pressure of the tire of the one of the wheels is in an abnormal state.

Inventors

  • Hiroaki Kobayashi

Assignees

  • TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date
20260505
Application Date
20230628
Priority Date
20221020

Claims (5)

  1. 1 . A wheel-state obtaining system, comprising: a plurality of air pressure sensors each of which is provided for a corresponding one of a plurality of wheels of a vehicle to detect an air pressure of a tire of the corresponding one of the plurality of wheels; a plurality of temperature sensors each of which is provided for a corresponding one of the plurality of wheels to detect a temperature of an inside of a tire of the corresponding one of the plurality of wheels; a vehicle state detection device configured to detect a state of the vehicle; and a controller, wherein the controller is configured to obtain a temperature conversion air pressure, which is the air pressure of the tire of each of the plurality of wheels when the temperature of the inside of the tire is a predetermined set temperature, based on a detected air pressure that is the air pressure detected by each of the plurality of air pressure sensors and a detected temperature that is the temperature detected by each of the plurality of temperature sensors, wherein, when a reduction amount of the temperature conversion air pressure of one of the plurality of wheels is greater than a reduction amount of the temperature conversion air pressure of each of other wheels except the one of the plurality of wheels, the controller determines that the air pressure of the tire of the one of the plurality of wheels is in an abnormal state, wherein the controller obtains, for each of the plurality of wheels, an air-pressure reduction value by subtracting a reference pressure from the temperature conversion air pressure, and wherein the controller determines that the air pressure of the tire of the one of the plurality of wheels is in the abnormal state when an absolute value of the air-pressure reduction value of the one of the plurality of wheels is greater than an absolute value of the air-pressure reduction value of each of the other wheels by an abnormality determination threshold, wherein, when the state of the vehicle detected by the vehicle state detection device is a stopped state, the controller determines whether the temperature conversion air pressure of each of the plurality of wheels has increased by a pressure regulation determination threshold or more, and wherein, when the controller determines that the temperature conversion air pressure of at least one of the plurality of wheels has increased by the pressure regulation determination threshold or more, the controller changes the reference pressure of each of the at least one of the plurality of wheels.
  2. 2 . The wheel-state obtaining system according to claim 1 , wherein the controller determines whether a gradient of decrease in the detected air pressure that is the air pressure of the tire of each of the plurality of wheels detected by each of the plurality of air pressure sensors is not less than a predetermined set gradient, wherein, when the controller determines that the gradient of decrease in the detected air pressure of at least one of the plurality of wheels is not less than the set gradient, the controller determines that the tire of each of the at least one of the plurality of wheels has blown out, wherein the controller determines whether the detected air pressure that is the air pressure of the tire of each of the plurality of wheels detected by each of the plurality of air pressure sensors is lower than a predetermined set pressure, and wherein, when the controller determines that the detected air pressure of at least one of the plurality of wheels is lower than the set pressure, the controller determines that the air pressure of the tire of the at least one of the plurality of wheels is abnormally low.
  3. 3 . The wheel-state obtaining system according to claim 1 , wherein the controller determines whether a gradient of decrease in the detected air pressure that is the air pressure of the tire of each of the plurality of wheels detected by each of the plurality of air pressure sensors is not less than a predetermined set gradient, wherein, when the controller determines that the gradient of decrease in the detected air pressure of at least one of the plurality of wheels is not less than the set gradient, the controller determines that the tire of each of the at least one of the plurality of wheels has blown out, wherein the controller determines whether the detected air pressure that is the air pressure of the tire of each of the plurality of wheels detected by each of the plurality of air pressure sensors is lower than a predetermined set pressure, and wherein, when the controller determines that the detected air pressure of at least one of the plurality of wheels is lower than the set pressure, the controller determines that the air pressure of the tire of the at least one of the plurality of wheels is abnormally low.
  4. 4 . The wheel-state obtaining system according to claim 1 , wherein the controller is configured to determine whether the wheel is in a slow leak state in which the air leaks from the tire, based on the state of reduction of the temperature conversion air pressure.
  5. 5 . A wheel-state obtaining system, comprising: a plurality of air pressure sensors each of which is provided for a corresponding one of a plurality of wheels of a vehicle to detect an air pressure of a tire of the corresponding one of the plurality of wheels; a plurality of temperature sensors each of which is provided for a corresponding one of the plurality of wheels to detect a temperature of an inside of a tire of the corresponding one of the plurality of wheels; and a controller, wherein the controller is configured to obtain a temperature conversion air pressure, which is the air pressure of the tire of each of the plurality of wheels when the temperature of the inside of the tire is a predetermined set temperature, based on a detected air pressure that is the air pressure of the tire of each of the plurality of wheels detected by each of the plurality of air pressure sensors and a detected temperature that is the temperature of the inside of the tire of each of the plurality of wheels detected by each of the plurality of temperature sensors, and wherein the controller determines, for each of the plurality of wheels, whether the air pressure is in the abnormal state based on a state of reduction of the temperature conversion air pressure of each of the plurality of wheels with respect to a reference pressure, wherein the wheel-state obtaining system includes a vehicle state detection device configured to detect a state of the vehicle, wherein, when the state of the vehicle detected by the vehicle state detection device is a stopped state, the controller determines whether the temperature conversion air pressure of each of the plurality of wheels has increased by a pressure regulation determination threshold or more, and wherein, when the controller determines that the temperature conversion air pressure of at least one of the plurality of wheels has increased by the pressure regulation determination threshold or more, the controller changes the reference pressure of each of the at least one of the plurality of wheels.

Description

REFERENCE TO RELATED APPLICATIONS This application claims priority from Japanese Patent Application No. 2022-168147 filed on Oct. 20, 2022. The entire content of the priority application is incorporated herein by reference. BACKGROUND ART The following disclosure relates to a wheel-state obtaining system configured to obtain a state of a wheel. A wheel-state obtaining system described in Patent Document 1 (Japanese Patent Application Publication No. 2022-090477) includes air pressure sensors each of which is provided for a corresponding one of a plurality of wheels to detect an air pressure of a tire of the corresponding wheel and a slow-leak-state obtaining portion configured to determine whether the plurality of wheels is in a slow leak state based on detected air pressures of the tires of the plurality of wheels, each of which is the air pressure of the tire detected by a corresponding one of the air pressure sensors. In the wheel-state obtaining system, there are obtained a first average value that is an average value of the detected air pressures of each wheel in a first period and a second average value that is an average value of the detected air pressures of each wheel in a second period. The slow-leak-state obtaining portion determines that one wheel is in the slow leak state when a difference between the first average value and the second average value of the one wheel is not less than a first threshold and a difference between the first average value and the second average value of each of other wheels is less than the first threshold. SUMMARY An aspect of the present disclosure relates to an improvement in a wheel-state obtaining system such as a technique of accurately determining whether a wheel is in a state in which an air pressure of a tire of the wheel is abnormal. In a wheel-state obtaining system according to one aspect of the present disclosure, a temperature conversion air pressure, which is an air pressure of a tire of each of a plurality of wheels when a temperature of an inside of the tire is a set temperature, is obtained based on a detected air pressure and a detected temperature of the tire of each wheel. When a reduction amount (positive value) of the temperature conversion air pressure of one wheel A among the plurality of wheels is greater than that of each of other wheels, it is determined that the one wheel A is in a state in which the air pressure of the tire is abnormal. In a traveling state of the vehicle, the air pressure of the tire may be decreased due to a decrease in the temperature of the inside of the tire. It is determined in the present wheel-state obtaining system whether the air pressure of the tire is abnormal based on the reduction amount of the temperature conversion air pressure. This eliminates a necessity to consider the decrease in the air pressure due to the decrease in the temperature. It is thus possible to accurately determine whether the air pressure of the tire of the wheel is abnormal. BRIEF DESCRIPTION OF THE DRAWINGS The objects, features, advantages, and technical and industrial significance of the present disclosure will be better understood by reading the following detailed description of an embodiment, when considered in connection with the accompanying drawings, in which: FIG. 1 is a perspective view conceptually illustrating a wheel-state obtaining system according to one embodiment of the present disclosure; FIG. 2 is a conceptual view of a principal part of the wheel-state obtaining system; FIG. 3 is a flowchart representing a slow-leak-state determination program stored in a memory of a body-side unit of the wheel-state obtaining system; FIG. 4 is a flowchart representing an air pressure abnormality determination program stored in the memory; FIG. 5 is a view illustrating a change in an air pressure of each wheel of a vehicle on which the wheel-state obtaining system is installed; and FIG. 6 is a view illustrating a change in an air-pressure reduction value of each wheel, which is a value obtained by subtracting a reference pressure from a temperature conversion air pressure. DETAILED DESCRIPTION Referring to the drawings, there will be described in detail a wheel-state obtaining system according to one embodiment of the present disclosure. As illustrated in FIG. 1, the wheel-state obtaining system includes: wheel-side units 12FL, 12FR, 12RL, 12RR respectively provided for four wheels of a vehicle, i.e., a front left wheel 10FL, a front right wheel 10FR, a rear left wheel 10RL, and a rear right wheel 10RR; and a body-side unit 16 provided for a body 14 of the vehicle. In the following description, the wheels 10, the wheel-side units 12, etc., will be referred to without suffixes such as FL, FR, RL, RR indicative of the corresponding wheel positions where it is not necessary to distinguish them by their wheel positions or where they are collectively referred to. As illustrated in FIG. 2, each wheel-side unit 12 includes, for instance, an