Thomson Coil Drive With Soft-Magnetic Frame for High Force Density
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Solution Overview
Problem
Existing nail setting devices face limitations with electromagnetic drives due to insufficient power and efficiency, high wiring complexity, and structural stress, particularly in highly dynamic applications like hand-held nail setting tools.
Innovation Solution
A nail setting device with an electrodynamic drive featuring a soft magnetic frame, a squirrel-cage rotor, and a capacitor discharge system, where the frame has a high saturation flux density and specific electrical conductivity, and strain relief mechanisms to manage radial forces and structural stress, utilizing a Thomson coil design with a flat excitation coil and a hollow cylindrical rotor for efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If electromagnetic drives (Thomson coils, railguns) are used to achieve high force and work capacity, then force and power are improved, but device complexity and circuitry effort increase significantly
Solution Approach 1:
The patent replaces complex electromagnetic circuitry with a simpler electrodynamic system using a squirrel-cage rotor and excitation coil. The mechanical-like rotor structure with conductive bars and end rings substitutes for complex electronic control circuits, achieving high force density through straightforward electromagnetic induction rather than sophisticated circuitry.
Solution Approach 2:
The patent changes the operational parameters by using a soft magnetic frame with specific saturation flux density (at least 1.0 T) and controlled electrical conductivity (at most 10^6 S/m). These parameter specifications optimize the balance between magnetic field generation and eddy current losses, achieving high force density without requiring overly complex control systems.
2Productivity
If highly dynamic electrodynamic drive is implemented, then productivity and response speed are improved, but structural stress and radial forces increase
Solution Approach 1:
The patent incorporates strain relief means positioned at critical locations where radial forces act on the excitation coil and frame. These strain relief features are designed in advance to absorb and distribute the high radial forces generated during rapid operation, preventing structural damage while enabling high productivity operation.
Solution Approach 2:
The patent employs a soft magnetic frame with composite properties - high saturation flux density (at least 1.0 T) combined with controlled electrical conductivity (at most 10^6 S/m). This composite material approach allows the frame to simultaneously provide strong magnetic field concentration for high productivity while limiting eddy current losses that would generate excessive heat and stress.
3Force
If soft magnetic frame with high saturation flux density is used, then magnetic field strength is improved, but eddy current losses increase due to higher electrical conductivity
Solution Approach 1:
The patent optimizes the electrical conductivity parameter of the soft magnetic frame to be at most 10^6 S/m, which is sufficiently conductive to support strong magnetic field generation but limited enough to reduce eddy current losses. This parameter optimization resolves the contradiction between achieving high magnetic field strength and minimizing energy losses.
Solution Approach 2:
The patent applies different material properties to different parts of the magnetic circuit. The soft magnetic frame has controlled conductivity to minimize losses, while the squirrel-cage rotor maintains high conductivity for efficient current induction. This local differentiation of material quality allows strong magnetic fields where needed while minimizing eddy current losses in the frame.
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 achieves high force density and efficient energy transfer, enabling effective nail setting with reduced structural stress and improved efficiency, while preventing damage to the drive components during operation.
Implementation Method 1
a first excitation coil, a soft magnetic frame, and a squirrel-cage rotor mounted to move along an axis
Implementation Method 2
the Lorentz force acting on the squirrel-cage rotor is preferably used to perform work
Implementation Method 3
the frame has a saturation flux density of at least 1.0 T
Implementation Method 4
a soft magnetic frame... which, in particular, in the manner of a pot magnet, represents an open magnetic circuit
Data Source
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AI summary
The invention relates to a highly dynamic electromagnetic drive of the Thomson coil type with a soft-magnetic frame, comprising - a first exciter coil (30), the winding height of which is greater than the length thereof and which is therefore flat; - a soft-magnetic frame (10) in which the first exciter coil (30) is arranged and supported thereon and which forms an open magnetic circuit in the manner of a cup magnet, which has an outer region (11), a bottom (12) and an inner region (13) and is open at the end, wherein the first exciter coil at least partially encloses the inner part (13) of the frame; - a squirrel cage rotor (40) which is preferably hollow-cylindrical, at least on the side facing the first exciter coil (30), is mounted such that it can move along a shaft, passes into the end opening in the frame (10) when in the stroke starting position and in the process at least partially encloses the inner part (13) of the frame. The frame (10) is formed entirely or mainly from a soft-magnetic composite material or one or more lamination stacks, said composite material having a saturation flux density of at least 1.5 T and an effective specific electrical conductivity of at most 10∧6 S/m. The first exciter coil (30) and/or the frame (10) have at least one means for relieving tensile load, in particular in the form of an enclosure, to absorb at least some of the radial forces arising perpendicular to the movement direction at the first exciter coil (30) during an actuation process. The Lorentz force acting on the squirrel cage rotor is used to perform work.