Ultrasonic Sensor Case Member Anisotropy Design
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Solution Overview
Problem
Ultrasonic sensors for automotive back sonar systems face challenges in achieving stable anisotropy in directional properties due to complex manufacturing processes and vibration issues, leading to high costs and unstable performance.
Innovation Solution
The design features a cylindrical outer case member with a piezoelectric element on its inner surface and a cylindrical inner case member with cutouts to reduce contact surface area, allowing for noticeable anisotropy in directional properties and reduced side vibration, using a metal material with higher density for the inner case member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the case member is provided with thick portions and thin portions to achieve desired directional properties, then anisotropy in directional properties is improved, but the structure becomes complex and manufacturing cost increases
Solution Approach 1:
The case member is divided into a bottom wall portion and a sidewall portion that are integrated through a continuous surface. The bottom wall includes a vibration suppression portion with reduced thickness that segments the structure to control vibration patterns, creating anisotropic directional properties without requiring multiple separate components or complex assembly
Solution Approach 2:
The vibration suppression portion is created by locally reducing the thickness of the bottom wall in specific areas while maintaining adequate thickness in other regions. This local variation in thickness creates the desired anisotropy in directional properties by controlling vibration characteristics at specific locations without making the entire structure complex
2Reliability
If the case member is provided with thick portions and thin portions to achieve desired directional properties, then anisotropy in directional properties is improved, but manufacturing cost increases due to complex processing
Solution Approach 1:
The vibration suppression portion is integrated directly into the bottom wall of the case member as a continuous structure, eliminating the need for separate components. This merging of functions into a single integrated part simplifies manufacturing processes and reduces cost while maintaining the anisotropic directional properties
3Reliability
If the hollow portion is formed to have an elliptical cross section to ensure anisotropy, then directional properties are improved, but the sidewall becomes thin and side vibration amplitude increases
Solution Approach 1:
The vibration suppression portion is specifically designed to control and reduce mechanical vibration in the sidewall region. By creating a thickness variation pattern in the bottom wall that couples with the sidewall, it dampens unwanted vibration modes and reduces side vibration amplitude while preserving the anisotropic directional properties through the overall geometry
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 achieves noticeable anisotropy in directional properties, reduces side vibration, and simplifies manufacturing, resulting in a more stable and cost-effective ultrasonic sensor with improved performance.
Implementation Method 1
a piezoelectric element provided on an inner surface side of a bottom wall of an outer case member
Implementation Method 2
an ultrasonic sensor used for, for example, back sonar or the like of an automobile
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
An ultrasonic sensor having stable anisotropy in directional properties is provided. ' A case member of an ultrasonic sensor according to the present invention includes an outer case member 10 having a cylindrical shape with a bottom and an inner case member 30. Cutout portions 36 having a predetermined size are provided so as to face each other in a lower portion of a sidewall 32 of the inner case member 30. The inner case member 30 is formed of a metal material having a higher density than that of the outer case member 10. Consequently, an elliptical vibrating-surface amplitude profile can be formed in a vibrating surface 20 of the ultrasonic sensor, and an ultrasonic sensor having noticeable anisotropy in directional properties can be provided. Further, an ultrasonic sensor with a small amount of displacement of side vibration in the ultrasonic sensor can be provided.