Passive SAW Sensor Embedded in Rubber for Tire Monitoring
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Solution Overview
Problem
Active tire pressure sensors are large, inconvenient, and not environment-friendly due to battery replacement needs, and they indirectly monitor tire temperature, which can lead to system failures and damage during tire vulcanization.
Innovation Solution
A patch-type passive surface acoustic wave sensing device with a surface acoustic wave sensor integrated into a multi-layered rubber structure and a PCB for support, allowing direct tire contact and real-time temperature monitoring, fixed using vulcanization or glue without battery reliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active tire pressure sensor with power supply and MCU is used, then the sensor can perform pressure and temperature monitoring, but the device size becomes large and requires periodic battery replacement
Solution Approach 1:
The patent extracts the power supply, MCU, and wireless communication module from the sensor assembly, leaving only the passive sensing elements (surface acoustic wave resonators). This eliminates the need for battery replacement while maintaining monitoring capability, directly resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The patent replaces the active electronic system (power supply + MCU + wireless module) with a passive surface acoustic wave-based system that uses mechanical vibrations to encode sensor data. The surface acoustic wave resonators naturally oscillate at frequencies that change with pressure and temperature, eliminating the need for active electronics and battery.
2Reliability
If the sensor is placed on tire valve or wheel hub, then the sensor can monitor tire parameters, but the temperature monitored is indirect and not real-time
Solution Approach 1:
The patent segments the sensing function from the mounting location, placing the passive surface acoustic wave sensor directly on the tire inner wall where it can directly contact the tire. This direct contact enables real-time temperature measurement of the tire itself rather than indirect measurement of air temperature inside the tire.
Solution Approach 2:
The patent uses a special adhesive layer as an intermediary between the sensor and the tire inner wall. This adhesive layer thermally couples the sensor to the tire, allowing the sensor to accurately measure tire temperature while protecting the sensor from direct exposure to harsh vulcanization conditions.
3Ease of manufacture
If the sensor is arranged on tire valve or around, then the sensor can be installed, but the risk of damaging the tire valve or sending module increases during vulcanization
Solution Approach 1:
Instead of placing the sensor on the outer surface of the tire where it would be exposed to vulcanization heat, the patent inverts the approach by placing the sensor on the inner wall of the tire. The sensor is positioned in a location that is protected from the harshest vulcanization conditions while still being able to measure tire parameters.
Solution Approach 2:
The patent uses a protective adhesive layer and positions the sensor away from the tire valve area to cushion it against the high temperatures and pressures of vulcanization. The sensor is pre-positioned in a safe zone that minimizes exposure to damaging conditions during the vulcanization process.
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 solution provides a compact, environment-friendly, and accurate tire pressure and temperature monitoring system that avoids battery replacement and harsh vulcanization conditions, ensuring reliable operation and reduced risk of sensor damage.
Implementation Method 1
a surface acoustic wave sensor, and at least a first rubber sheet and a second rubber sheet... the surface acoustic wave sensor comprises pins on the bottom part
Implementation Method 2
the surface acoustic wave sensor comprises pins on the bottom part, free ends of the pins are connected to an antenna
Data Source
AI summary
A patch-type passive acoustic waving sensing device includes a surface acoustic wave sensor and at least a first and second rubber sheets. A cross-section of each of the first and second rubber sheets is larger than that of the surface acoustic wave sensor. A bottom of the surface acoustic wave sensor is on an upper surface of the first rubber sheet, and a first central hole allowing the surface acoustic wave sensor to penetrate therethrough is formed in a center of the second rubber sheet. The surface acoustic wave sensor penetrates the first central hole, and the second rubber sheet is fixedly connected to the upper surface of the first rubber sheet. The surface acoustic wave sensor includes pins at the bottom thereof such that free ends of the pins are connected to an antenna, and the antenna and some of the pins are inside the first rubber sheet.