Piezoelectric Driving Device Actuator Configuration for Stability
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Solution Overview
Problem
Existing piezoelectric driving devices using a single piezoelectric actuator struggle to generate a large driving force and experience attitude instability due to moments generated between inner and outer rings of bearings.
Innovation Solution
A piezoelectric driving device employing multiple piezoelectric actuators positioned inside the outer circumferential part of the bearing, with their center of pressing forces aligned along the rotation axis, reduces moments and stabilizes the relative attitude of the first and second members by applying forces parallel to the rotation axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single piezoelectric actuator is used, then the device structure is simple, but the driving force is insufficient
Solution Approach 1:
The patent divides the single actuator into multiple piezoelectric actuators (at least two) that work together to generate driving force. Each actuator applies force at different positions, and their combined effect produces sufficient total driving force while maintaining coordinated motion through the bearing support structure.
Solution Approach 2:
Multiple piezoelectric actuators are combined to work together as a unified driving system. The actuators are positioned and configured to apply forces that combine constructively, with their center of pressing forces aligned inside the bearing's outer circumferential part to achieve both sufficient force and stable attitude.
2Stability of the object's composition
If a single piezoelectric actuator contacts the rotor from one side, then the actuator configuration is simple, but moment is generated between inner and outer rings of bearings causing attitude variation
Solution Approach 1:
The patent positions the center of pressing forces from the piezoelectric actuators asymmetrically inside the outer circumferential part of the bearing rather than at the center. This asymmetric positioning within the bearing radius reduces the moment arm between inner and outer rings, thereby reducing generated moments and stabilizing the relative attitude of the supporting part and rotor.
Solution Approach 2:
The configuration of multiple actuators with their pressing force centers positioned inside the bearing's outer circumferential part creates a counterbalancing effect that reduces the moment generated between bearing rings. The distributed force application counteracts the destabilizing moment that would occur with single-sided actuator contact.
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 enhances driving force and stabilizes the relative attitude of the members, reducing rattles and enabling high-accuracy operation in applications like electronic component conveyance, robots, projectors, and printers.
Implementation Method 1
a piezoelectric actuator that drives a driven member by vibrating a vibrator using a piezoelectric element
Data Source
AI summary
A first member, a second member, a bearing that rotatably supports the second member about a rotation axis relative to the first member, a driven member placed on the first member, and a plurality of piezoelectric actuators that transmit driving forces for rotating the second member about the rotation axis relative to the first member to the driven member are provided, and the piezoelectric actuators are supported by the second member while being pressed against the first member or the member fixed thereto, and, as seen from a direction along the rotation axis, a center of pressing forces from the plurality of piezoelectric actuators to the driven member is located inside of an outer circumferential part of the bearing.