Vibration Actuator Oval Motion Nodal Line Design
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Solution Overview
Problem
Existing vibration-type actuators face challenges in downsizing and stabilizing the position of the vibrating body while maintaining effective driving performance, as they often require complex supporting structures and are prone to uneven pressure distribution and rotational moments due to the placement of projecting portions.
Innovation Solution
A vibration-type actuator design featuring a rectangular flat-shaped elastic body with projecting portions and a piezoelectric element, where two bending vibration modes are excited to generate oval motions, allowing for stable positioning and reduced size through optimized nodal line configurations and contact portion placement, which minimizes rotational moments and enhances frictional driving force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If projecting portions are added to the elastic body to generate driving vibrations, then driving performance is improved, but device complexity and structural stability deteriorate due to the need for complex supporting structures
Solution Approach 1:
The projecting portions are integrated directly into the elastic body as a unified structure, eliminating the need for separate supporting structures. The elastic body itself serves both as the vibrating element and the support for the projecting portions, reducing structural complexity while maintaining driving performance.
Solution Approach 2:
The supporting structure is extracted and eliminated entirely. Instead of adding separate supports for the projecting portions, the design relies on the elastic body's inherent properties and the strategic placement of nodal lines to provide stability without additional structural elements.
2Power
If projecting portions are placed to generate driving vibrations, then driving performance is improved, but position stability deteriorates due to uneven pressure distribution and rotational moments
Solution Approach 1:
The elastic body is designed with non-uniform local properties through the strategic placement of nodal lines. The nodal lines are positioned to create specific vibration patterns that concentrate stress and deformation in controlled regions, allowing the projecting portions to generate driving vibrations while maintaining overall position stability through localized vibration control.
Solution Approach 2:
The design utilizes controlled mechanical vibrations in two bending modes to generate oval motions at the projecting portions. By exciting specific vibration modes with defined nodal line patterns, the system achieves stable position holding while maintaining effective driving performance through the combination of vibration modes.
3Volume of moving object
If the elastic body is downsized to reduce actuator size, then device miniaturization is achieved, but driving performance deteriorates due to increased resonance frequencies
Solution Approach 1:
The design utilizes controlled mechanical vibrations in two bending modes to generate oval motions at the projecting portions. By exciting specific vibration modes with defined nodal line patterns, the system achieves stable position holding while maintaining effective driving performance through the combination of vibration modes.
Solution Approach 2:
The design changes the vibrational parameters by combining two different bending vibration modes. This allows the system to maintain effective driving performance at smaller sizes by utilizing resonant frequencies and vibration mode combinations that are optimized for compact dimensions, rather than relying on single-mode vibrations that would require larger dimensions.
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 design achieves downsizing of the actuator while maintaining stable driving characteristics and high performance by reducing resonance frequencies and ensuring stable position holding against pressurizing forces, minimizing losses in frictional driving force transmission.
Implementation Method 1
an electro-mechanical energy conversion element 12 joined to one surface of the elastic body 11
Implementation Method 2
vibrations in a first bending vibration mode... and vibrations in a second bending vibration mode... are excited
Implementation Method 3
reducing resonance frequencies and ensuring stable position holding
Implementation Method 4
by bringing the driven body 2 into pressure contact with the upper end faces of the projecting portions 13... the vibrating body 10 and the driven body 2 are moved relatively to each other
Data Source
AI summary
A vibration-type actuator is downsized and stably holds the position of a vibrating body. In the vibrating body, it is possible to excite vibrations in a first bending vibration mode with two nodal lines that do not cross each other but cross short sides of an elastic body, and no nodal line that connects two long sides of the elastic body together, and a second bending vibration mode in which amplitude peaks of vibration in an out-of-plane direction of a flat-shaped plane of the elastic body lie in six respective areas formed by dividing the flat-shaped plane, and in the adjoining areas, vibrations at the amplitude peaks are in opposite phases. Combined vibrations in the first and second bending vibration modes cause an oval motion of the projecting portion, moving the vibrating body and a driven body relatively to each other in a lateral direction of the elastic body.