Vehicle Bumper Molded Article Millimeter Wave Transmissivity
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Solution Overview
Problem
Modern vehicle bumpers attenuate millimeter waves from radar devices, leading to reduced detection accuracy of surrounding objects due to excessive wave attenuation.
Innovation Solution
A molded article for vehicles with a thickness corresponding to an integer multiple of the half wavelength of the millimeter wave, specifically between 1.8 mm and 2.2 mm or 3.1 mm and 3.5 mm, to minimize wave cancellation and ensure adequate stiffness, using a polypropylene base member and a thin coating film with a relative permittivity of 2.93, optimizing transmissivity to better than -3 dB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the molded article is increased to ensure adequate stiffness, then the structural strength is improved, but the millimeter wave transmissivity deteriorates due to excessive attenuation
Solution Approach 1:
The molded article has different thicknesses in different regions: a first thickness in the millimeter wave transmission area and a second thickness (greater than the first) in the remaining area. This local differentiation allows the transmission area to maintain high transmissivity while the thicker remaining area provides adequate stiffness and structural strength.
2Reliability
If the thickness of the molded article is decreased to improve millimeter wave transmissivity, then the wave attenuation is reduced, but the stiffness of the molded article deteriorates
Solution Approach 1:
The molded article has different thicknesses in different regions: a first thickness in the millimeter wave transmission area and a second thickness (greater than the first) in the remaining area. This local differentiation allows the transmission area to maintain high transmissivity while the thicker remaining area provides adequate stiffness and structural strength.
3Reliability
If the thickness of the molded article is made non-uniform to optimize transmissivity in the transmission area, then the millimeter wave transmission is improved, but the manufacturing complexity increases
Solution Approach 1:
The thickness parameter of the molded article is optimized to be an integer multiple of half the wavelength of the millimeter wave in the article. This parameter change creates constructive interference of transmitted waves while minimizing reflection, thereby maximizing transmissivity without requiring complex multi-layer structures.
4Reliability
If the thickness of the molded article is set to an integer multiple of half wavelength to maximize transmissivity, then the millimeter wave transmission is improved, but the stiffness may be insufficient in the transmission area
Solution Approach 1:
The molded article has different thicknesses in different regions: a first thickness in the millimeter wave transmission area and a second thickness (greater than the first) in the remaining area. This local differentiation allows the transmission area to maintain high transmissivity while the thicker remaining area provides adequate stiffness and structural strength.
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 minimizes millimeter wave attenuation, ensuring reliable detection of obstacles by maintaining adequate stiffness and uniform transmissivity, enhancing the performance of millimeter wave radar systems.
Implementation Method 1
the millimeter wave reflected by the boundary between the molded article and the surrounding air is prevented from canceling the millimeter wave transmitted through the molded article
Implementation Method 2
The millimeter wave transmitted from the radar device is attenuated when passing through the bumper
Implementation Method 3
a combined relative permittivity of the base member and the coating film being about 2.93
Data Source
AI summary
Provided is a molded article (1) of a vehicle (S) designed to be placed in a path of millimeter wave transmitted from a radar device (7) that can minimize the attenuation of the millimeter wave. The molded product has a thickness as measured in a direction of the path of the millimeter wave transmitted from the radar device which is an integer multiple of a half wavelength of the millimeter wave in the molded article.