Ultrasonic Sensor Weight Placement for Dual-Frequency Operation

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Solution Overview

Problem

Existing ultrasonic sensors face difficulties in easily attaching a transducer element due to the placement of mass elements on the base surface, limiting their ability to transmit and receive ultrasonic signals of different frequencies effectively.

Innovation Solution

The design includes a bottomed cylindrical case with weight portions on the circumferential wall, allowing the piezoelectric element to be easily attached and enabling the sensor to transmit and receive ultrasonic signals of different frequencies by adjusting the vibration modes through strategically positioned weight portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mass elements are disposed on the base surface to enable transmission and reception of ultrasonic signals, then the sensor can transmit and receive two ultrasonic signals of different frequencies, but the transducer element cannot be easily attached to the base surface

Engineering Contradiction:

Improveability to transmit and receive two ultrasonic signals of different frequenciesVSAvoidease of attaching transducer element to base surface

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The mass elements are relocated from the base surface (two-dimensional plane) to the circumferential wall portion (three-dimensional space), specifically positioned at the outer peripheral surface. This spatial relocation to another dimension allows both the transducer element attachment and mass element function to coexist without interference.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The housing is segmented into distinct functional zones: the base surface is dedicated to transducer element attachment, while the circumferential wall portion houses the mass elements. This segmentation separates the attachment function from the ultrasonic signal function, resolving the conflict between ease of manufacture and signal transmission capability.

Inventive Principle:

Principle #1Segmentation

2Reliability

If mass elements are disposed on the base surface, then the sensor can achieve specific vibration modes for ultrasonic transmission, but the structural complexity increases and attachment becomes difficult

Engineering Contradiction:

Improvevibration mode control for ultrasonic transmissionVSAvoidstructural complexity and attachment difficulty

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Mass elements are positioned on the circumferential wall portion's outer peripheral surface rather than on the base surface. This three-dimensional positioning maintains the vibration mode control capability while simplifying the overall structure and improving attachment accessibility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Different portions of the housing are assigned different qualities: the base surface has a smooth, attachment-optimized surface for the transducer element, while the circumferential wall portion has mass elements positioned to provide specific vibration characteristics. This local differentiation achieves both reliability and reduced complexity.

Inventive Principle:

Principle #3Local quality

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 allows for easy attachment of the piezoelectric element and efficient transmission and reception of ultrasonic signals at two distinct frequencies, enhancing the sensor's operational flexibility and accuracy in distance measurement and object detection.

Implementation Method 1

a piezoelectric element 120 disposed on the bottom portion 111 inside the case 110

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The two weight portions 130 are provided on the circumferential wall portion 115 outside the case 110

Methodology Applied

Scientific EffectConverse piezoelectric effect: Converse Piezoelectric Effect

Implementation Method 3

When the bottom portion 111 bends toward one side in the axial direction during vibration at a frequency of a first vibration mode

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentUS12123987B2Ultrasonic sensor

Publication Date: 2024.10.22 MURATA MFG CO LTD

AI summary

An ultrasonic sensor includes a case, a piezoelectric element, and two weight portions. The case includes a circumferential wall portion extending in an axial direction. The two weight portions are provided on the circumferential wall portion outside the case so as not to overlap each other as seen in the axial direction. When a bottom portion of the ultrasonic sensor bends toward one side in the axial direction during vibration at a frequency of a first vibration mode, the two weight portions incline toward the other side in the axial direction. When the bottom portion bends toward one side in the axial direction during vibration at a frequency of a second vibration mode, the two weight portions incline toward one side in the axial direction.