Cascade Magnetic Actuator Design for Fast Force Generation
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Solution Overview
Problem
Magnetic drives based on the pot magnetic circuit principle face limitations in realizable pole area and actuation speed due to large pole faces, which increase mass and inertia, and existing electromagnets for valves have inhomogeneous field distribution and reduced force generation due to flux passing through multiple air gaps.
Innovation Solution
An electric magnetic actuator design with a cascaded arrangement of disc-shaped elements, where magnetic flux passes through only one air gap, enhancing force generation and using a simple sleeve as a magnetic yoke to simplify manufacturing and reduce installation space and energy requirements, while providing mechanical guidance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the pole face area is increased to improve force generation, then the magnetic force increases, but the mass and inertia increase, reducing actuation speed
Solution Approach 1:
The magnetic actuator is divided into multiple cascaded stages, each with its own coil and pole pieces. This segmentation allows the total force to be distributed across multiple smaller magnetic circuits, reducing the pole face area of each individual stage while maintaining overall force output, thereby reducing mass and inertia for faster actuation.
Solution Approach 2:
The invention transitions from a single-stage radial magnetic circuit to a multi-stage cascaded arrangement that utilizes the axial dimension. By stacking multiple magnetic stages along the axial direction, the system achieves increased force without proportionally increasing the radial pole face area, thus reducing rotational inertia.
2Force
If flux passes through multiple air gaps as in conventional electromagnets, then the magnetic circuit is complete, but the force generation is reduced and the field distribution becomes inhomogeneous
Solution Approach 1:
The magnetic flux path is segmented into multiple independent cascaded stages, where each stage has its own coil and magnetic circuit. This segmentation ensures that flux from each coil passes through only one air gap per stage, avoiding the cumulative effect of multiple series air gaps and maintaining homogeneous field distribution across the entire actuator.
Solution Approach 2:
Multiple magnetic stages are combined in a cascaded arrangement where the output of one stage feeds into the next. This merging of stages allows the system to achieve complete magnetic circuits while ensuring that flux from each individual coil passes through only one air gap, maintaining force and field homogeneity.
3Reliability
If a complex electromagnet structure with radial coil fitting is used, then the magnetic circuit functions, but the manufacturing difficulty and cost increase
Solution Approach 1:
Instead of fitting coils radially from the interior of the core as in conventional designs, the invention inverts the approach by mounting coils axially on the outer surface of the cylindrical core. This inversion simplifies manufacturing, as coils can be easily attached to the external cylindrical surface without requiring internal access or complex radial assembly.
Solution Approach 2:
The cylindrical core serves multiple functions: it provides the magnetic circuit path, supports the axial mounting of coils, and acts as a mechanical structure for assembly. This multi-functionality reduces the need for separate components and simplifies the overall manufacturing process while maintaining magnetic circuit functionality.
4Area of stationary object
If more installation space is allocated in the axial direction, then larger pole faces can be accommodated, but the available space in compact injectors is limited
Solution Approach 1:
The invention utilizes the axial dimension efficiently by cascading multiple magnetic stages along the axis. This allows the system to achieve increased effective pole face area through the stacking of stages without requiring a proportional increase in the radial dimensions, thus fitting within the limited axial space of compact injectors.
Solution Approach 2:
Multiple magnetic stages are nested in a cascaded arrangement where each stage is positioned within or adjacent to the previous stage along the axial direction. This nesting allows maximum utilization of the available axial space, accommodating multiple pole faces and coils without exceeding the overall length constraints of the injector.
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 increases force generation efficiency, reduces manufacturing costs and complexity, and improves actuation speed by minimizing inductance and allowing for redundancy in coil elements, while maintaining mechanical stability and efficient use of space.
Implementation Method 1
The magnetic flux generated by the coil only has to pass through one air gap instead of two, as a result of which the force that can be generated is significantly increased
Implementation Method 2
Magnetic drives that work according to the pot magnetic circuit principle generate a magnetic force F = -1/2 μ 0 A 1 H 1 2
Data Source
Figure 1
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Figure 3
AI summary
The actuator (10) has an armature counter piece (12) and an armature (14), which is arranged inside the counter piece and extends longitudinally. The counter piece has a main side (16) with several coil units (18a-18d) and exciter pole collars (20a-20d), which are magnetically connected with one another by the main side. The armature has armature pole collars (22a-22d), which extend radially to the counter piece. The exciter pole collars act on the armature pole collars during activation of the coil units, where the coil units are arranged in the main side.