Quick-Switching Lifting Magnet with Short-Circuit Ring
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Solution Overview
Problem
Conventional lifting magnets face challenges in achieving rapid switching times due to the trade-off between high magnetic force and armature mass, where increased armature cross-section for force requires more mass, leading to slower movement, and high inductance results in slower current increase and magnetic flux.
Innovation Solution
A lifting magnet that combines a conventional reluctance principle-based design with an electrodynamic actuator featuring a short-circuit ring loosely coupled to the armature, where the short-circuit ring is positioned to minimize protrusion into the excitation coil space, allowing for rapid current increase and magnetic field generation, enhancing switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the armature cross-section is increased to generate large forces for rapid acceleration, then the magnetic force is improved, but the armature mass increases causing slower movement
Solution Approach 1:
The patent combines two different actuation principles: the conventional reluctance principle (providing high magnetic force through the excitation coil and armature) and the electrodynamic principle with a short-circuit ring (providing rapid response through induced currents). This merging allows the system to achieve both high force and fast switching by utilizing the complementary strengths of both principles simultaneously.
2Force
If the armature cross-section is increased to generate large forces, then the magnetic force is improved, but the inductance of the coil increases causing slower current rise
Solution Approach 1:
The short-circuit ring acts as an intermediary element that decouples the relationship between armature size and current rise time. By introducing this additional conductive component, the system can maintain large armature cross-sections for high force while the short-circuit ring's induced currents provide a rapid response mechanism that compensates for the increased inductance.
3Speed
If electrodynamic actuators with short-circuit rings are used for rapid switching, then the switching speed is improved, but the efficiency is reduced due to large leakage field and losses
Solution Approach 1:
The patent merges the electrodynamic actuator with the conventional lifting magnet, allowing the system to leverage the rapid switching capability of the electrodynamic principle while the reluctance principle provides efficient force generation. The combination enables fast switching without relying solely on the inefficient electrodynamic mechanism for the entire actuation process.
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 combination results in a significantly faster-switching lifting magnet with peak forces nearly twice those of individual principles, achieving millisecond-range switching times by leveraging both reluctance and Lorentz forces effectively.
Implementation Method 1
Conventional lifting magnets usually work according to the reluctance principle. In this case, an iron armature that can be moved by energizing an excitation coil is provided within a metallic housing that is part of a magnetic circuit. The way it works is based on the force that is exerted on magnetic interfaces in the inhomogeneous magnetic field.
Implementation Method 2
The advantage of electrodynamic actuators is that the short-circuit ring is flooded with a rapidly changing magnetic field. This induces a voltage in the ring, which carries a current that also generates a magnetic field.
Implementation Method 3
electrodynamic actuators are also known, which are based on the effect of the Lorentz force. A Lorentz force occurs when a current-carrying conductor is in a magnetic field, with the current-carrying conductor being movably mounted relative to the magnetic field.
Data Source
Figure 1~2
Figure 3
AI summary
The solenoid (10) has a housing (11) comprising an upper housing cover (12) and a lower housing cover (14) and a housing wall (16). A pole core (20) is extended along a center axis of housing. A front surface (21) of pole core is made to face a movable armature (30). A short circuit ring (60) is loosely anchor with a plunger (40) that is connected with movable armature.