Load detection sensor and load detection sensor unit
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Solution Overview
Problem
Existing load detection sensors in vehicles are prone to erroneous load detection due to temperature variations, particularly at high temperatures, where resin films used in seating detection systems can bend under reduced strength, leading to false positives from smaller loads.
Innovation Solution
A load detection sensor unit featuring a metal plate bonded with an adhesive layer to a thinner insulating sheet, where the total thickness of the insulating sheet and adhesive layer is less than the metal plate, reduces deformation and variations caused by temperature changes, and includes a spacer with an elastic modulus of at least 10 MPa to stabilize the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin film is used for load detection, then the sensor can be manufactured with ease and flexibility, but the sensor becomes prone to bending and erroneous detection at high temperatures due to reduced strength
Solution Approach 1:
The patent uses a composite structure combining a metal plate (high strength, low thermal expansion) with a resin film (flexible, easy to manufacture). The metal plate serves as the load-bearing element that maintains dimensional stability at high temperatures, while the resin film provides flexibility and ease of manufacturing. This composite approach resolves the contradiction by leveraging the complementary properties of both materials.
Solution Approach 2:
The patent changes the material parameter from purely resin-based to metal-based load-bearing structure. By substituting the resin film with a metal plate for the critical load detection function, the sensor maintains reliability at high temperatures while the overall device still benefits from resin-based components for manufacturing ease.
2Stability of the object's composition
If the thickness of the insulating sheet is increased to provide structural support, then the sensor becomes more stable, but the deformation amount increases at high temperatures leading to erroneous detection
Solution Approach 1:
The patent combines a thin insulating sheet with a metal plate to achieve both stability and precision. The metal plate provides the necessary structural support and thermal stability, while the thin insulating sheet minimizes deformation. The synergistic combination allows the sensor to remain stable without suffering from excessive deformation at high temperatures.
Solution Approach 2:
The patent applies different thickness requirements to different components: the insulating sheet is kept thin to minimize deformation, while the metal plate provides the necessary structural support. This local differentiation of quality (thickness) resolves the contradiction by optimizing each component for its specific function.
3Reliability
If a metal plate is used instead of resin film, then the sensor becomes resistant to temperature-induced deformation, but the ease of manufacture and flexibility are reduced
Solution Approach 1:
The patent uses a composite structure where the metal plate provides reliability and temperature resistance, while resin-based components (insulating sheets, adhesive layers, encapsulation) maintain ease of manufacture and flexibility. This composite approach allows the sensor to benefit from both material types without sacrificing either reliability or manufacturability.
Solution Approach 2:
The patent segments the sensor into different functional components: the metal plate handles load-bearing and temperature resistance, while separate resin-based components handle insulation, bonding, and encapsulation. This segmentation allows each component to be optimized for its specific function, with the metal plate providing reliability and the resin components providing ease of manufacture.
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 configuration effectively prevents erroneous load detection by minimizing deformation and maintaining accurate load detection across varying temperatures, ensuring reliable seating detection.
Implementation Method 1
an adhesive layer that is disposed between the second insulating sheet and the metal plate and bonds the second insulating sheet and the metal plate together
Implementation Method 2
when the metal plate is pressed, the metal plate is bent, and the second insulating sheet of the sensor sheet is also bent following the bending of the metal plate
Data Source
Figure 1
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AI summary
A load detection sensor 5 includes: a sensor sheet 50 including a main block 56m that is a part of a first insulating sheet made of resin and a main block 57m that is a part of a second insulating sheet made of resin, the main block 56m and the main block 57m facing each other, a first electrode 56e that is disposed on a face of the main block 57m of the first insulating sheet, and a second electrode 57e that is disposed between the first insulating sheet and the second insulating sheet and paired with the first electrode 56e; and a metal plate 60 that is disposed on a face of the second insulating sheet, the face being opposite to a face of the main block 57m facing the main block 56m, at least in a part overlapping the first electrode 56e and the second electrode 57e. The thickness of the second insulating sheet including the main block 57m is less than the thickness of the metal plate 60.