Tire Tread Deformation Sensor Using Flexible Printed Circuit
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Solution Overview
Problem
Existing sensors for measuring tire deformation are limited by their punctual nature, leading to significant errors when encountering ground irregularities, and they disturb the true deformation of the pneumatic casing due to their impact on local rigidity.
Innovation Solution
A device with a bending sensor that covers a larger area of the tire's contact zone, oriented in the circumferential direction, and having a flexibility greater than the radial stiffness of the tire, allowing for continuous measurement of deformation across 10-80% of the contact area, reducing the impact of point irregularities and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a point-like sensor is used to measure tire deformation, then the device complexity is reduced, but the measurement precision deteriorates due to significant errors from ground irregularities
Solution Approach 1:
The patent divides the measurement function into multiple discrete sensors arranged in an array across the contact patch. Instead of using a single point sensor, multiple sensors segment the measurement area to capture deformation data at multiple locations, thereby reducing the impact of local ground irregularities on overall measurement accuracy.
Solution Approach 2:
The patent transitions from one-dimensional point measurement to two-dimensional area measurement by arranging sensors in a grid pattern across the contact patch. This dimensional expansion allows the system to capture spatial distribution of deformation and filter out localized irregularities through spatial averaging.
2Ease of operation
If a traditional sensor is mounted on the tire, then the measurement function is achieved, but the reliability deteriorates because the sensor disturbs the true deformation of the pneumatic casing
Solution Approach 1:
The patent employs thin-film flexible printed circuit boards to mount the sensor array. These flexible substrates conform to the tire's curved surface without adding significant rigidity, thereby minimizing disturbance to the natural deformation of the pneumatic casing while enabling easy integration of multiple sensors.
Solution Approach 2:
The patent changes the mechanical parameters of the sensor mounting system by using flexible materials with low stiffness compared to the tire structure. This parameter change ensures that the mounting system does not significantly alter the tire's deformation characteristics while still providing stable sensor attachment.
3Measurement precision
If multiple sensors are arranged in an array, then the measurement precision improves by averaging ground irregularities, but the device complexity increases
Solution Approach 1:
The patent uses flexible printed circuit boards that serve multiple functions: they provide mechanical support for the sensor array, enable electrical connections between sensors, and conform to the tire's geometry. This multi-functionality reduces the need for separate mounting structures and simplifies the overall device complexity despite the increased number of sensors.
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
This solution provides more reliable and accurate deformation measurements, averaging out ground irregularities and minimizing disturbance to the tire's deformation, thus enhancing the quality of sensor signals and safety systems like ABS and ESP.
Implementation Method 1
at least one flexural sensor exhibits a flexural stiffness less flexible than the radial stiffness kradial of the tire casing
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3c
AI summary
The invention relates to a device for evaluating the deformation of a pneumatic tyre casing, comprising: – a pneumatic tyre casing having an axis of rotation, comprising a crown and having a radial stiffness; – when the pneumatic tyre casing is comprised within a mounted assembly, the footprint of the pneumatic tyre casing having a dimension L adc in the axial direction; – an electronic device comprising a bending sensor; characterized in that the bending sensor comprises an active part having a main dimension comprised between 10% and 80% of the dimension Ladc, in that the active part of the sensor is situated in line with the crown, in that the main dimension of the active part is oriented in the circumferential direction of the pneumatic tyre casing, and in that the bending sensor has a bending stiffness that is lower than the radial stiffness of the pneumatic tyre casing.