In-Tire Voltage Sensing for Low-Speed Wear Estimation
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Solution Overview
Problem
Existing tire wear estimation methods, such as those using radial acceleration signals, face accuracy issues at low vehicle speeds due to deteriorated signal-to-noise ratios, and fail to accurately detect wear and ground contact state changes, which are influenced by tire pressure, mounting state, and wheel load.
Innovation Solution
A tire state estimation method involving a power generator inside the tire that generates voltage based on deformation, acquiring time-series measurement data, identifying peaks, and estimating wear or ground contact state from peak values or intervals, utilizing a power generator with insulating films that change contact area with pressure, allowing accurate estimation even at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radial acceleration signals are used for tire wear estimation, then wear amount can be estimated, but estimation accuracy deteriorates at low vehicle speeds due to deteriorated signal-to-noise ratio
Solution Approach 1:
The patent replaces the mechanical vibration-based acceleration sensor system with an electrical field-based power generator system. The power generator detects changes in the electrical field caused by tire deformation and ground contact, providing a measurement mechanism that is not dependent on vehicle speed-induced vibrations, thereby resolving the contradiction between measurement accuracy and vehicle speed.
Solution Approach 2:
The patent changes the measurement parameter from radial acceleration (which diminishes at low speeds) to voltage signal from power generator (which remains detectable at low speeds). By detecting the voltage generated through deformation-induced changes in insulating film contact area, the system maintains measurement sensitivity across all vehicle speed ranges.
2Measurement precision
If power generator with insulating films is used inside the tire, then accurate wear and ground contact state estimation is achieved even at low speeds, but device complexity increases
Solution Approach 1:
The power generator structure serves multiple functions simultaneously: it generates voltage through deformation-induced contact area changes in insulating films, detects ground contact state through voltage signal characteristics, and provides structural integration within the tire. This multi-functionality reduces the need for separate sensing systems, offsetting the added complexity with consolidated functionality.
Solution Approach 2:
The patent utilizes thin insulating films as the core sensing element within the power generator. These flexible thin films deform with tire deformation, changing their contact area and generating voltage signals. The use of thin films minimizes the space required for the sensing mechanism while maintaining sensitivity, thereby reducing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively estimates tire wear and ground contact state with improved accuracy at low speeds, providing information on wear, mounting state, tire pressure, and wheel load, enhancing vehicle control and maintenance.
Implementation Method 1
The first insulating film and the second insulating film are configured such that one is positively charged and the other is negatively charged due to a change in the true contact area
Data Source
AI summary
This tire state estimation method includes the following. (1) Disposing, on the inner side of a tire, at least one power generator that generates voltage in response to deformation of the tire. (2) Acquiring measurement data in a time series obtained by measuring, while the tire is rotating, the voltage and/or a physical quantity corresponding to the voltage. (3) Identifying a peak that repeatedly appears in the measurement data. (4) Identifying a value of the peak and/or an interval of the peak. (5) Estimating the state of the tire on the basis of the identified value and/or the identified interval. The power generator is provided with a first member and a second member. The first member and the second member are configured such that one is positively charged and the other is negatively charged in accordance with pressure applied to the first member and the second member.