Vibration Actuator Foam Structure for Stable Drive and Pressure Uniformity
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Solution Overview
Problem
Vibration-type actuators using foamed members exhibit lower drive characteristics compared to those using felt, and there is a need for improved stability and efficiency over a long period.
Innovation Solution
A vibration-type actuator design incorporating a foamed member with a specific siloxane bond ratio (NQ/ND ≥ 0.09) and optimized air bubble structure, including independent air bubbles with an average equivalent circle diameter greater than 120 μm, to enhance drive characteristics and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a high-rigidity urging member is used to apply uniform pressure to the vibrator, then pressure uniformity is improved, but vibration of the vibrator is hindered leading to deterioration of drive characteristics
Solution Approach 1:
A foamed member is introduced as an intermediary between the urging member and the vibrator. This foamed member has a cellular structure that allows it to transmit pressure uniformly while its porous nature permits vibration transmission, thus mediating between the conflicting requirements of pressure uniformity and vibration freedom
Solution Approach 2:
The urging member is designed with a foamed (porous) structure containing siloxane bonds. This porous structure enables the member to apply uniform pressure through its cell wall distribution while allowing vibration waves to pass through the void spaces, resolving the contradiction between pressure application and vibration transmission
2Reliability
If a vibration attenuation member is disposed between the urging member and the vibrator to prevent vibration hindrance, then drive characteristics are improved, but pressure uniformity deteriorates
Solution Approach 1:
The urging member is designed as a composite structure combining foamed material with specific siloxane bond ratios (NQ/ND ≥ 0.09). This composite structure integrates both pressure transmission capability through the foam matrix and vibration attenuation properties, eliminating the need for a separate vibration attenuation member and resolving the contradiction between drive characteristics and pressure uniformity
3Reliability
If felt is used as a vibration attenuation member, then drive characteristics are improved, but long-term stability decreases
Solution Approach 1:
The material composition of the urging member is changed from traditional felt or simple foamed materials to a specific foamed structure with controlled siloxane bond ratios (NQ/ND ≥ 0.09). This parameter change in material composition provides both improved drive characteristics and enhanced long-term stability, as the siloxane-based foamed structure maintains its mechanical properties over extended periods
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 actuator achieves stable drive characteristics over a long period with improved efficiency by using a foamed member that uniformly applies pressure while attenuating vibrations, maintaining performance even at low temperatures.
Implementation Method 1
a foamed member that is in contact with the vibrator... The foamed member includes siloxane bonds, Si—O—Si, made of silicon and oxygen
Implementation Method 2
optimized air bubble structure, including independent air bubbles with an average equivalent circle diameter greater than 120 μm, to enhance drive characteristics and maintain stability
Data Source
AI summary
A vibration-type actuator of the present disclosure includes a vibrator including an electromechanical energy conversion element and an elastic body, the elastic body having a plate portion and protruding portions that protrude in the same direction out of a plane of the plate portion, a contact body that is in contact with the protruding portions of the vibrator and that moves relative to the vibrator, a foamed member that is in contact with the vibrator, and an urging member that urges the vibrator toward the contact body via the foamed member. The foamed member includes siloxane bonds, Si—O—Si, made of silicon and oxygen, and a ratio NQ/ND of the number NQ of Q units to the number ND of D units is greater than or equal to 0.09 in silicon contained in the foamed member.