Ultrasonic Sensor Damping Member and Foamable Resin Design
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Solution Overview
Problem
Ultrasonic sensors face issues with vibration damping, positional accuracy of terminals, and resistance to external stress, leading to potential disconnection and assembly challenges.
Innovation Solution
A cylindrical ultrasonic sensor design featuring a damping member between the casing and substrate, preventing direct contact and using foamable resin to suppress vibration, while ensuring perpendicularity and positional accuracy of terminals through a damping member and substrate configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the substrate is attached to the casing such that the substrate is in direct contact with side surfaces of the casing, then automatic mounting is enabled, but vibration of the piezoelectric element is transmitted through the casing and the substrate and is damped through the terminals
Solution Approach 1:
A damping member made of silicone rubber is introduced as an intermediary between the substrate and the casing. This damping member suppresses the transmission of vibration from the piezoelectric element through the substrate and casing, while still enabling automatic mounting through the terminals. The damping member acts as a mediator that decouples the vibration transmission path while maintaining the mechanical connection for mounting purposes.
2Reliability
If the substrate is fitted to a hole formed at the center of a damping member, then vibration transmission is suppressed, but the perpendicularity of the terminals with respect to the casing and the piezoelectric element is degraded and the positional accuracy is reduced
Solution Approach 1:
The damping member is designed with non-uniform thickness, being thicker at the peripheral portion and thinner at the central portion. This local variation in thickness allows the damping member to provide effective vibration suppression at the periphery while maintaining adequate space and alignment guidance at the center for the substrate and terminals. The peripheral portion provides the necessary damping effect, while the central portion maintains the perpendicularity and positional accuracy of the terminals.
3Reliability
If foamable resin is used to fill the inner space of the casing, then vibration of the casing and ultrasonic waves remaining in the casing are reduced, but the foamable resin may deform under external stress leading to disconnection
Solution Approach 1:
The patent employs a composite structure combining the foamable resin (for vibration absorption) with the damping member made of silicone rubber (for stress resistance). The damping member provides mechanical strength and resistance to external stress, while the foamable resin fills the remaining space and absorbs vibration. This composite approach allows the system to benefit from both vibration reduction and stress resistance properties.
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 effectively reduces vibration damping, enhances terminal positional accuracy, and increases resistance to external stress, preventing disconnection and facilitating easier assembly by maintaining the levelness and positional accuracy of terminals.
Implementation Method 1
the piezoelectric element 3 is excited by applying a drive voltage to the terminals 5a and 5b. The bottom surface of the casing 2 is vibrated in response to vibration of the piezoelectric element 3. As a result, ultrasonic waves are emitted in a direction perpendicular to the bottom surface
Implementation Method 2
ultrasonic waves that are emitted toward the inside of the casing 2 are dispersed and absorbed by a large number of pores in the foamable resin 4
Implementation Method 3
vibration of the piezoelectric element 3 is transmitted through the casing 2 and the substrate 6 and is damped through the terminals 5a and 5b
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An ultrasonic sensor in which vibration of a piezoelectric element is not easily damped, which has high positional accuracy at end portions of terminals, and which is resistant to external stress is provided. A ultrasonic sensor 10 includes a cylindrical casing 12 having a bottom. The casing 12 has a piezoelectric element 16 on a bottom surface thereof. A substrate 20 is attached to an end face of an opening portion of the casing 12 with a damping member 18 provided therebetween such that the damping member 18 covers the opening portion. Pin terminals 22a and 22b are provided so as to extend through the substrate 20 and the damping member 18 and are electrically connected to the piezoelectric element 16 with lead wires 24a and 24b or the like. An inner space of the casing 12 is filled with foamable resin 26.