Battery-less Tire Pressure Sensor Using Electret Vibration Energy
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Solution Overview
Problem
Current air pressure management devices for vehicle tires face challenges in power supply and practical implementation, particularly in providing reliable air pressure information under varying conditions.
Innovation Solution
A vehicle tire system incorporating a ferroelectric member with floating electrodes, an electret-vibration electric power generation unit, an air pressure sensor, and a wireless communication unit that uses external vibrations to generate power and transmit air pressure data without a battery, ensuring reliable operation even under severe conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery is installed in the tire to power the air pressure sensor and wireless communication unit, then the tire can continuously monitor and transmit air pressure data, but the device complexity and weight increase, and the battery requires maintenance and replacement
Solution Approach 1:
The tire monitoring system powers itself by harvesting mechanical energy from the tire's rotation and vibrations through the electret-vibration electric power generation unit. This self-powered approach eliminates the need for external batteries or power cables, allowing the air pressure sensor and wireless communication unit to operate autonomously without increasing device complexity or requiring maintenance.
Solution Approach 2:
The system utilizes the natural vibrations and rotational motion of the tire during vehicle operation to generate electrical energy. The electret-vibration electric power generation unit converts these mechanical vibrations into electrical power, which continuously charges the energy storage component to power the sensor and communication functions, resolving the contradiction between reliability and device complexity.
2Ease of operation
If an electret-vibration electric power generation unit is used to generate power from tire vibrations, then the system becomes battery-less and maintenance-free, but the power generation reliability under severe conditions (high temperature, stationary vehicle, engine off) becomes uncertain
Solution Approach 1:
The system incorporates an energy storage component (capacitor or battery) that accumulates electrical energy in advance during periods when vibration power generation is sufficient. This stored energy serves as a buffer to ensure continuous operation during severe conditions such as high temperatures, stationary vehicles, or when the engine is off, thereby maintaining reliability while preserving maintenance-free operation.
Solution Approach 2:
The electret material is specifically selected and engineered to maintain stable surface electric potential (approximately 100 volts) across a wide temperature range, including up to 100°C. This parameter optimization ensures that power generation reliability is maintained under severe thermal conditions, resolving the contradiction between ease of operation and reliability.
3Device complexity
If the air pressure sensor and wireless communication unit are powered by the electret-vibration unit, then no battery is needed, but the electric power generated must be sufficient to run both components simultaneously under all conditions
Solution Approach 1:
The energy storage component accumulates electrical energy in advance during normal vehicle operation when vibrations are sufficient. This preliminary energy accumulation ensures that both the air pressure sensor and wireless communication unit can operate simultaneously even during severe conditions when vibration power generation may be insufficient, resolving the contradiction between simplified power supply structure and energy sufficiency.
Solution Approach 2:
The system dynamically manages power distribution based on available energy. The control unit monitors the charge level of the energy storage component and adjusts the operation of the wireless communication unit accordingly, enabling both components to function when energy is sufficient while maintaining the simple battery-less structure. This dynamic approach resolves the contradiction between device complexity and energy sufficiency.
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
Enables a battery-less tire with effective air pressure detection and transmission, maintaining functionality even when the vehicle is stationary or the engine is off, by harnessing vibrations for power generation and optimizing electric power use.
Implementation Method 1
a movable member including a plurality of electret portions stably maintaining a surface electric potential of approximately 100 volts at a temperature of 100° C.
Implementation Method 2
the plurality of electret portions and the plurality of opposed electrode portions being arranged in a line alternately so as to face the plurality of floating electrode portions, the movable member being supported by the ferroelectric member so that the plurality of electret portions and the plurality of opposed electrode portions are moved by an external vibration in parallel to the plurality of floating electrode portions
Implementation Method 3
a ferroelectric member including a plurality of floating electrode portions arranged in a line on one surface thereof
Data Source
AI summary
A wireless communication device includes an electric power generation unit, an electric power accumulation unit, a sensor supplied with the electric power from the electric power accumulation unit, and a wireless communication unit supplied with the electric power from the electric power accumulation unit, for transmitting the sensed information outputted by the sensor to outside of the wireless communication device. A storage unit stores the sensed information outputted by the sensor. A control unit controls operation of the wireless communication unit, the sensor and/or the storage unit in accordance, at least in part, with the electric power accumulated in the electric power accumulation.