Vibration-Type Actuator Frequency Difference Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vibration-type actuators experience abnormal noise and instability due to unnecessary vibrations when the frequency of the driving voltage approaches resonance frequencies, leading to 'squeal' noise at low driving speeds.
Innovation Solution
A vibration-type actuator design that includes a vibration body with an electro-mechanical energy conversion element and an elastic body, where the resonance frequency difference between higher natural vibration modes and the driving frequency is maximized to prevent coincident frequency differences, reducing unnecessary vibrations and stabilizing the driving process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the frequency of driving voltage is swept to approach resonance frequency from high frequency side, then the driving speed is improved, but abnormal noise and instability occur due to self-excited vibration
Solution Approach 1:
The patent applies preliminary anti-action by designing the vibration body structure to create a frequency difference buffer before the harmful self-excited vibration can occur. The third vibration mode resonance frequency is intentionally positioned to maintain a larger frequency difference from the driving frequency compared to the fundamental mode, preemptively preventing the coincident frequency differences that cause squeal noise and instability during frequency sweeping operations.
2Ease of operation
If the frequency difference between third vibration mode resonance frequency and driving frequency is reduced, then the frequency response is improved, but self-excited vibration and abnormal noise increase
Solution Approach 1:
The patent applies parameter changes by optimizing the geometric parameters of the vibration body (such as the dimensions and positioning of protrusions and recesses) to control the resonance frequencies. By adjusting these physical parameters, the design ensures that the frequency difference between the third vibration mode resonance and driving frequency remains sufficiently large, preventing self-excited vibration while maintaining acceptable frequency response characteristics.
3Ease of manufacture
If the vibration body structure is simplified, then the manufacturing cost is reduced, but the control of resonance frequency and vibration suppression becomes difficult
Solution Approach 1:
The patent applies segmentation by dividing the vibration body into distinct functional regions: a body portion and protrusion portions with specific geometric features. This segmentation allows independent optimization of each region's contribution to the overall vibration characteristics, enabling precise control of resonance frequencies through localized geometric modifications rather than requiring complex overall restructuring.
Solution Approach 2:
The patent applies asymmetry by designing the protrusions and recesses with specific asymmetric geometries that influence the vibration modes. The asymmetric structure creates distinct resonance frequencies for different vibration modes, particularly ensuring the third mode maintains a larger frequency difference from driving frequency, thereby suppressing self-excited vibration through geometric asymmetry rather than complex material or structural solutions.
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 solution effectively reduces abnormal noise and ensures stable driving by maintaining a larger frequency difference between the resonance frequency of the third vibration mode and the driving frequency, preventing self-excited vibrations and enhancing durability.
Implementation Method 1
a piezoelectric device 102a joined to the elastic body 102b
Implementation Method 2
the driven body 103 receives friction driving force by elliptic motions of the two projections 102c
Implementation Method 3
vibrations in two bending vibration modes are excited in the vibration body 102
Data Source
AI summary
A vibration-type actuator that is capable of reducing an unnecessary vibration during driving includes a vibration body configured by connecting an electro-mechanical energy conversion element and an elastic body. A driven body is in pressure contact with the vibration body. A controller moves the vibration body and the driven body relatively by a vibration that is excited in the vibration body by applying driving voltage to the electro-mechanical energy conversion element so that a difference between a resonance frequency in a natural vibration mode of the vibration body that is higher than an upper limit frequency of a predetermined driving frequency range and that is nearest to the upper limit frequency and a frequency of the driving voltage is greater than a difference between a resonance frequency in a natural vibration mode used for moving the vibration body and the driven body relatively and the frequency of the driving voltage.