Linear Actuator Offset Adjustment via Stator Core Recess
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Solution Overview
Problem
Existing movable iron core linear actuators face challenges in adjusting the offset position without increasing manufacturing cost or device size, as changing the thickness and material of permanent magnets or introducing additional mechanisms like flat springs can be costly and complex.
Innovation Solution
Forming a space portion in the stator core with a cut-out facing portion to adjust the offset position, which balances the gravitational force and magnetic offset force without adding components or altering manufacturing processes significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the position of the linear actuator is changed to a longitudinal position, then the actuator can be installed in different orientations, but the offset force by the permanent magnets becomes smaller than the gravity and the moving element is displaced downward from the center of the movable range
Solution Approach 1:
The patent introduces a recess portion in the facing portion of the stator core, creating a localized structural modification. This recess portion selectively reduces the magnetic flux in specific regions, allowing precise adjustment of the offset force distribution to counteract gravity in longitudinal installation positions while maintaining adaptability to different orientations.
Solution Approach 2:
The facing portion of the stator core is designed with asymmetric structure by introducing a recess portion on one side. This asymmetric design creates unbalanced magnetic flux distribution that generates the necessary offset force to counteract gravity when installed in longitudinal position, while still allowing the actuator to function in horizontal positions.
2Manufacturing precision
If the thickness and material of the permanent magnets are changed to adjust the magnetic flux, then the offset position can be adjusted, but the number of components increases or the cost of permanent magnets increases
Solution Approach 1:
Instead of modifying the permanent magnets themselves, the patent extracts the adjustment function to the stator core by introducing a recess portion. This approach separates the adjustment mechanism from the permanent magnets, allowing offset position tuning without changing the magnet components, thereby avoiding increased device complexity and cost.
Solution Approach 2:
The patent changes the geometric parameter of the stator core's facing portion by introducing a recess portion with specific dimensions. This parameter change (the recess depth and width) directly controls the magnetic flux distribution and enables precise adjustment of the offset position without requiring multiple types of permanent magnets or additional components.
3Manufacturing precision
If additional mechanisms such as flat springs are introduced to adjust the offset position, then the balanced point can be adjusted, but the manufacturing cost and device size increase
Solution Approach 1:
The stator core's facing portion with the recess portion serves dual functions: it maintains the structural integrity of the stator core and simultaneously provides the offset adjustment function. This self-service design eliminates the need for separate adjustment mechanisms like flat springs, reducing both device size and manufacturing cost while achieving precise offset control.
Solution Approach 2:
The facing portion of the stator core is designed to perform multiple functions: it provides the magnetic circuit path, structural support, and offset adjustment capability through the recess portion. This multi-functional design consolidates what would otherwise require separate components, reducing the overall actuator size and complexity.
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 approach allows for precise adjustment of the offset position without increasing costs or size, enhancing the actuator's performance by maximizing reciprocation amplitude and reducing the risk of collision, while maintaining cost-effectiveness and simplicity.
Implementation Method 1
The self holding force is not external force which acts on the moving element by a mechanical element, such as a flat spring, but self force produced in the moving element by the magnetic flux of the permanent magnets
Implementation Method 2
The self holding force acts on the moving element so as to return the moving element to a predetermined position if the moving element has been displaced from the predetermined position
Implementation Method 3
A magnetic flux produced by energization of coil weakens a magnetic flux produced in a magnet situated in a necessary direction between the pair of permanent magnets, and strengthens a magnetic flux produced in the other magnet
Implementation Method 4
magnetic flux produced by energization of coil
Implementation Method 5
the offset force by the permanent magnets becomes smaller than the gravity which acts on the moving element at the center of the movable range and the moving element is displaced downward from the center of the movable range
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
To provide a movable iron core linear actuator capable of properly adjusting an offset position without any increase in manufacturing cost or device size. A movable iron core linear actuator includes a magnetic circuit (mc) which causes a moving element (2) to reciprocate. The magnetic circuit (mc) includes an iron core (20) constituting the moving element (2), a stator core (10) including a facing portion (10c) which faces the iron core (20), a pair of permanent magnets (12a, 12b) disposed in the facing portion (10c) along a reciprocating direction and having inverted magnetic poles at their surfaces which face the iron core, and a coil (11) wound around the stator core (10). Energization to coil (11) causes the moving element (2) to reciprocate. When the coil (11) is not energized, offset force (F4) is applied to the moving element (2) by the magnetic flux produced by the permanent magnets (12a, 12b). A space portion (30) having low magnetic permeability compared with the stator core (10) is provided in a state in which a part of the facing portion (10c) is removed in an area, which is a magnetic flux path, between a part of the facing portion (10c) of the stator core (10) and the permanent magnet (12b). Thus, an offset position which is a balanced point of the gravity (mg) acting on the moving element (2) and the offset force (F4) by the permanent magnets (12) is changed to a position (ps2) from a position (ps4) that is the offset position in a case in which no space portion (30) is provided.