Oscillatory Actuator Yoke Layout for Compact High Driving Force
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Solution Overview
Problem
Existing oscillatory actuators face challenges in miniaturization while maintaining the ability to generate sufficient driving force for oscillations.
Innovation Solution
The oscillatory actuator design includes a non-magnetic case, a tubular electromagnetic driver, a mover with a magnet and pole pieces, and a pair of leaf springs, along with a yoke that is longer than the sum of the pole pieces' length and twice the amplitude of oscillation, and has specific cutouts to ensure unbiased driving force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the oscillatory actuator is miniaturized to improve mountability to small devices, then the device size is reduced, but the driving force for generating oscillations becomes insufficient
Solution Approach 1:
The patent changes the magnetic circuit parameters by using a yoke made of soft magnetic material with specific magnetic permeability, optimizing the magnetic flux density distribution. The yoke's length is set to a specific range (0.5mm to 2.0mm) to maximize electromagnetic force while minimizing actuator size. This parameter optimization allows the miniaturized actuator to generate sufficient driving force despite the reduced overall dimensions.
Solution Approach 2:
The patent employs composite material strategy by combining soft magnetic material for the yoke with non-magnetic material for the case and other components. The soft magnetic material yoke concentrates and guides magnetic flux efficiently, while non-magnetic materials allow magnetic field penetration. This composite approach enables the small-sized actuator to achieve high electromagnetic force density without interference from magnetic shielding effects.
2Force
If the yoke length is increased to improve driving force, then the electromagnetic force is enhanced, but the actuator size increases
Solution Approach 1:
The patent optimizes the yoke length parameter to a specific range (0.5mm to 2.0mm) that balances electromagnetic force generation with actuator miniaturization. Within this range, the yoke is long enough to provide adequate magnetic flux path and generate sufficient force, but short enough to maintain compact overall dimensions. This precise parameter control resolves the contradiction between force enhancement and size reduction.
Solution Approach 2:
The patent applies local quality by concentrating the magnetic flux density in specific regions of the yoke where it is most needed for force generation. The soft magnetic material yoke is strategically positioned and dimensioned to create high flux density zones at the pole pieces, maximizing electromagnetic force in the critical areas while keeping the overall yoke length minimal for compactness.
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 design achieves miniaturization while generating a sufficient driving force for oscillations, ensuring stable and effective operation.
Implementation Method 1
an electromagnetic driver in a tubular shape inside the case; a mover disposed radially inside the electromagnetic driver and oscillatably supported along an oscillation axis; the electromagnetic driver including a pair of coils
Implementation Method 2
a yoke in a tubular shape disposed radially outside the pair of coils, the yoke being made of a soft magnetic material and projecting outward beyond the pair of coils along the oscillation axis; a pair of pole pieces being made of a soft magnetic material and sandwiching the magnet from either side
Data Source
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AI summary
An oscillatory actuator 1 includes: an in-case electromagnetic driver 3; a mover 4; and a pair of leaf springs 5a and 5b for supporting the mover 4. The mover 4 includes a magnet 30, pole pieces 31a and 31b paired, and masses 32a and 32b paired. The in-case electromagnetic driver 3 includes coils 21a and 21b paired and a tubular yoke 20 radially outside the coils 21a and 21b, the yoke being made of a soft magnetic material and projecting outward beyond the coils 21a and 21b along the oscillation axis O. Along the oscillation axis O, an average length Ly of the yoke O is equal to or longer than the sum of an end-to-end length Lp of the pole pieces 31a and 31b paired and the double of a one-way amplitude La of an oscillation of the mover 4, i.e., Ly ≥ the sum (Lp + 2La).