Linear Motor Actuator Phase-Shifted Thrust Control
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Solution Overview
Problem
Conventional voice coil motors face challenges in controlling the mover when it moves at high speeds or has a large stroke, as the voice coil can exit the magnetic field, leading to instability and limited frequency range due to the reliance on mechanical resilience from elastic bodies, which can result in resonance and structural brittleness.
Innovation Solution
A linear motor actuator design featuring permanent magnets with N and S poles and coils arranged in a specific configuration to generate phase-shifted thrusts, allowing the mover to be controlled without mechanical resilience, with alternating currents passed through the coils to manage movement and oscillation across the stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastic body is mounted on the voice coil to return it into the magnetic field, then the voice coil can be controlled when it exits the magnetic field, but the oscillation frequency becomes restricted due to resonance with the natural frequency of the elastic body
Solution Approach 1:
The patent replaces the mechanical elastic body return system with an electromagnetic control system. Multiple coils are arranged around the permanent magnet, and by controlling the current direction and magnitude in these coils, the voice coil is returned to the magnetic field without mechanical contact. This eliminates resonance issues and expands the usable frequency range while maintaining control capability.
Solution Approach 2:
The patent divides the single coil into multiple coils arranged in different directions around the permanent magnet. This segmentation allows independent control of each coil, enabling precise positioning and return of the voice coil without relying on a single elastic body, thereby avoiding resonance constraints.
2Reliability
If an elastic body is used to connect the stator and mover, then the voice coil can return to the magnetic field, but the structure becomes brittle due to bending forces in directions other than oscillation
Solution Approach 1:
The patent replaces the mechanical elastic body connection with an electromagnetic field-based return mechanism. Multiple coils are positioned to provide support and return forces without physical connection, eliminating the brittleness issue while maintaining the ability to return the voice coil to the magnetic field.
3Speed
If the voice coil operates at high speeds or with large stroke, then the movement performance is improved, but the voice coil exits the magnetic field and cannot be controlled
Solution Approach 1:
The patent segments the coil system into multiple coils arranged around the permanent magnet. This configuration creates an extended magnetic field coverage area, allowing the voice coil to maintain control during high-speed and large-stroke operations. The segmented coil structure ensures that at least some coils remain within the magnetic field during extended excursions.
Solution Approach 2:
The patent transitions from a single-direction coil arrangement to a multi-dimensional coil configuration surrounding the permanent magnet. This spatial arrangement in multiple dimensions extends the effective magnetic field coverage, enabling control during high-speed and large-stroke movements that would cause a single-coil system to exit the magnetic field.
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 enables reliable oscillation of the mover from low to high frequencies without mechanical resonance, ensuring stability and flexibility in movement control, and enhances resilience at stroke ends, allowing for precise positioning and high-speed operation.
Implementation Method 1
The operational principle of the voice coil motor utilizes Fleming's left-hand rule that thrust is generated when current is passed through a coil in a magnetic field created by a permanent magnet
Implementation Method 2
alternating currents having same phases are passed through the first coil and the second coil... phase of thrust generated in the first coil and phase of thrust generated in the second coil are shifted from each other
Data Source
AI summary
Provided is a linear motor actuator capable of oscillating a mover without using mechanical resilience of an elastic body. A first permanent magnet 3a and a second permanent magnet 3b magnetized in an axis direction are disposed in a mover 4 in the direction of the axis. A first coil 1a and a second coil 1b are disposed in a stator 2 so as to surround the first permanent magnet 3a and the second permanent magnet 3b, respectively. Alternating currents having the same phase are applied to the first coil 1a and the second coil 1b such that the phase of thrust generated in the first coil 1a and that of thrust generated in the second coil 1b are shifted from each other. At this moment, a center-to-center pitch LC1 between the center of the first coil 1a and that of the second coil 1b in the axis direction differs from a pole-to-pole pitch LM1 of the mover.