Piezoelectric Drive Device Axial Downsizing
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Solution Overview
Problem
Existing piezoelectric drive devices face challenges in downsizing along the rotation axis due to the arrangement of the vibrator and driven member, which limits their compactness and efficiency.
Innovation Solution
The piezoelectric drive device incorporates a rotor with a driven part divided into three portions, where the first portion is coupled to the bearing, the second portion overlaps with the bearing in a plan view, and the third portion has a contact surface with the vibrating unit, allowing for a compact design by overlapping the vibrating unit and rotor in a plan view from a perpendicular direction, thereby reducing the axial size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the vibrator and driven member are arranged in the thickness direction (along the rotation axis), then the structure is simple and easy to manufacture, but the device cannot be downsized in the axial direction
Solution Approach 1:
The patent transitions from a one-dimensional axial arrangement to a two-dimensional planar arrangement by overlapping the driven part with the bearing in a plan view. This allows the vibrator and driven member to be arranged in the radial direction rather than the axial direction, achieving downsizing in the thickness direction while maintaining structural simplicity
Solution Approach 2:
The driven part is designed with multiple portions (first, second, and third portions) that are sequentially connected from the rotation axis toward the outer circumference. The second portion overlaps with the bearing in plan view, creating a nested spatial arrangement where components occupy different radial and axial spaces, enabling compact axial dimensions
2Volume of moving object
If the driven part is divided into three portions with specific arrangements, then the device can be downsized and clearance is improved, but the manufacturing complexity increases
Solution Approach 1:
The driven part is segmented into three distinct portions: a first portion coupled to the bearing's inner ring, a second portion overlapping the bearing in plan view, and a third portion with a contact surface for the vibrator. This segmentation allows each portion to be optimized for its specific function while enabling the overall compact axial design
3Reliability
If the contact surface is positioned at the inner side of both ends of the predetermined region, then abrasion-related interference is reduced, but the structural complexity increases
Solution Approach 1:
The contact surface for the vibrator is extracted and positioned on the third portion, which is separated from the bearing coupling region. This spatial separation removes the contact interface away from the bearing area, preventing abrasion particles from interfering with bearing operation while maintaining structural integrity
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 enables the piezoelectric drive device to be downsized in the axial direction, reduces abrasion-related interference, and enhances clearance for placement, leading to improved compactness and reduced friction, thus enhancing the device's efficiency and reliability.
Implementation Method 1
a vibrating unit having a piezoelectric element and applying a drive force for rotating the rotor to the driven part by displacement of the piezoelectric element
Data Source
AI summary
A piezoelectric drive device includes a rotor having a driven part and rotating around a rotation axis, a vibrating unit having a piezoelectric element and applying a drive force for rotating the rotor to the driven part by displacement of the piezoelectric element, and a bearing supporting the rotor. The driven part has a first portion, a second portion, and a third portion sequentially connected, the first portion has a predetermined region along an axial direction of the rotation axis and coupled to an inner ring of the bearing within the predetermined region, the second portion overlaps with the bearing in a plan view from the axial direction, and the third portion has a contact surface in contact with the vibrating unit at an inner side of both ends of the predetermined region in a plan view from a direction perpendicular to the axial direction.