Electromagnetic Opposing Field Actuators for Linear Bidirectional Motion
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Solution Overview
Problem
Conventional electromagnetic actuators face limitations in achieving bidirectional action with uniform force across displacement distance and linearly proportional force to applied current, due to constraints such as narrow air gaps, high magnetic field requirements, and complex control challenges, especially in applications requiring high precision and reliability.
Innovation Solution
The development of electromagnetic opposing field actuators with a novel design featuring stationary permanent magnets and movable electromagnetic coils or vice versa, allowing for symmetrical bidirectional force generation with a large working air gap, low magnetic field losses, and linear force scaling over a wide dynamic range, utilizing a housing made of ferromagnetic material and a shaft of magnetically inert material to minimize magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional solenoids and moving coil actuators are used to achieve bidirectional motion, then force capability is improved, but the force versus displacement relationship becomes nonlinear and asymmetric, requiring springs for bidirectional motion
Solution Approach 1:
The actuator is divided into two symmetric electromagnetic subsystems (first and second electromagnetic coils with first and second permanent magnets) that operate in opposition. Each subsystem generates force in one direction, and by controlling the excitation of these segmented subsystems, the actuator achieves bidirectional motion with symmetric and linear force versus displacement characteristics, eliminating the need for mechanical springs.
Solution Approach 2:
The patent employs symmetric asymmetry - two identical electromagnetic subsystems arranged oppositely with equal but opposite magnetic polarities. This symmetric configuration creates opposing electromagnetic forces that are linear and symmetric with respect to displacement, allowing the actuator to produce equal force in both directions without requiring asymmetric mechanical elements like springs.
2Force
If high magnetic field intensity is used to drive the moving element, then force output is improved, but the air gap must be narrowed and magnetic circuit complexity increases
Solution Approach 1:
The patent changes the magnetic field configuration parameter by using opposing field arrangements with symmetric coil-magnet subsystems. This parameter change allows the actuator to maintain high force output over extended displacement ranges without requiring narrow air gaps, as the opposing field configuration distributes the magnetic flux more efficiently across the working gap.
3Adaptability or versatility
If permanent magnets and electromagnetic coils are arranged to generate opposing fields, then bidirectional force generation is improved, but magnetic field losses increase
Solution Approach 1:
The patent extracts and eliminates the need for mechanical spring elements and complex magnetic return paths by using opposing electromagnetic fields. The symmetric coil-magnet subsystems generate forces in opposite directions, and the magnetic fields are configured to minimize leakage and maximize useful work, reducing overall magnetic field losses while maintaining bidirectional capability.
4Force
If conventional electromagnetic actuators are used, then force generation is improved, but device complexity increases due to required ancillary mechanisms
Solution Approach 1:
The patent merges the bidirectional force generation capability directly into the electromagnetic structure itself, eliminating the need for separate mechanical spring elements, complex magnetic circuits, or ancillary mechanisms. The first and second electromagnetic coils with their respective permanent magnets are integrated into a unified opposing field system that inherently provides symmetric bidirectional force generation.
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
These actuators provide high force, bidirectional action, high speed response, and low power dissipation with a linear force versus displacement relationship, enabling extended travel distances and reliable operation without the need for ancillary mechanisms, thus overcoming the limitations of traditional solenoids and moving coils.
Implementation Method 1
an electromagnetic coil arranged on the central portion of the shaft, wherein the electromagnetic coil is capable of generating a force when energized that causes linear displacement of the shaft in either direction along the longitudinal axis depending on a direction of current through the electromagnetic coil
Implementation Method 2
a first captive permanent magnet arranged on the first end wall and having an inward facing pole; a second captive permanent magnet arranged on the second end wall and having an inward facing pole arranged to repel the inward facing pole of the first permanent magnet causing the first and second permanent magnets to have opposing magnetic fields
Implementation Method 3
a housing comprising a ferromagnetic material, wherein the housing has a first end wall, a second end wall opposite the first end wall
Data Source
AI summary
Electromagnetic actuators capable of generating a symmetrical bidirectional force are disclosed. The electromagnetic actuators include a housing made of a ferromagnetic material and a shaft made of a magnetically inert material movable along an axis within the housing. In one type of actuator, captive permanent magnets are arranged on opposite interior end walls of the housing and an electromagnetic coil is mounted on a central portion of the shaft. The electromagnetic coil is capable of generating a force when energized that causes linear displacement of the shaft in either direction along its axis depending on the direction of current through the electromagnetic coil. In another type of actuator, captive electromagnetic coils are arranged on opposing inner end walls of the housing, and a permanent magnet is mounted on a central portion of the shaft. The electromagnetic coils are capable of generating a force when energized that causes linear displacement of the shaft in either direction along its axis depending on a direction of current through the electromagnetic coils.