Vehicle Impact Sensor Using Piezoresistive Carbon Material
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Solution Overview
Problem
Existing impact sensors in vehicles, such as g-sensors and membrane switch sensors, face challenges in detecting impacts early and reliably due to mechanical softness in modern car designs, integration issues, and sensitivity to temperature and humidity, while also lacking information on the time evolution of impact force.
Innovation Solution
A strain-sensitive impact sensor using metal-containing carbon materials with piezoresistive properties, integrated into a flexible polymer sheet, allowing for early and reliable impact detection with minimal size and shape constraints, and capable of withstanding temperature and humidity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If membrane switch sensors are used for impact detection, then detection speed and sensitivity are improved, but the sensors are large in size and require straight integration with respect to the vertical direction, causing integration problems when installed into bumpers
Solution Approach 1:
The patent uses a flexible polymer sheet as the substrate for the sensor element, allowing the sensor to be bent and integrated into curved bumper surfaces. This resolves the contradiction by enabling fast detection (inherent property of membrane sensors) while achieving easy integration through flexibility, directly addressing the limitation of rigid large sensors that cannot be curved.
Solution Approach 2:
The sensor is divided into a thin flexible polymer sheet substrate with a strain-sensitive layer, allowing it to be integrated as a compact component rather than a large rigid structure. This segmentation enables the sensor to maintain fast detection capabilities while being small enough for easy integration into vehicle bumpers.
2Speed
If membrane switch sensors are used for impact detection, then fast detection of impact is achieved, but the sensors are influenced by humidity and temperature
Solution Approach 1:
The patent changes the material parameters by using a metal-containing carbon material with piezoresistive properties that exhibits stable electrical characteristics across varying temperature and humidity conditions. This resolves the contradiction by maintaining fast detection response while reducing sensitivity to environmental factors through careful selection of material properties.
Solution Approach 2:
The sensor uses a composite structure combining a polymer substrate with a metal-containing carbon strain-sensitive layer. This composite material approach allows the sensor to achieve fast detection speed while the specific material composition provides stability against humidity and temperature influences.
3Measurement precision
If g-sensors are used for impact characterization, then crash-related acceleration effects are detected, but detection efficiency is hampered due to mechanically softer materials and design constraints of modern car front-ends
Solution Approach 1:
The patent replaces traditional mechanical g-sensors with an electrical resistance-based detection system. The strain-sensitive element changes electrical resistance in response to mechanical deformation, substituting mechanical measurement with electrical measurement. This resolves the contradiction by providing reliable detection efficiency through electrical signals while maintaining accurate impact characterization through resistance changes, overcoming the limitations of mechanically softer modern car front-ends.
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 sensor provides fast and reliable detection of impacts with varying resistance measurements, enabling early activation of safety devices and accurate assessment of impact severity, while being easily integratable into vehicle components with flexible design and resistance to environmental factors.
Implementation Method 1
the sensor material is a metal-containing carbon material. These materials are known to have a resistance that changes when they are subjected to strain, i.e. they are piezoresistive
Data Source
AI summary
An impact sensor for a vehicle. The impact sensor includes at least one strain-sensitive sensor element which comprises a sensor material, and at least two terminals, between which the sensor material is electrically connected. The sensor material is a metal-containing carbon material.