Permanent Magnet Pole Piece Hermetic Sealing Method
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Solution Overview
Problem
Existing methods for mounting permanent magnets in large electrical machines face challenges such as corrosion, brittleness, and the need for expensive surface protection, as well as difficulties in magnetization and removal of demagnetized magnets, particularly due to heat input from welding or soldering processes which degrade the filling mass and compromise the seal.
Innovation Solution
A method involving the manufacturing of permanent magnet pole pieces with a base plate, protective cover, and filling mass, where the protective cover is fixed to the base plate, the cavity is evacuated, and the filling mass is injected and cured, providing a hermetically sealed environment without contamination or heat degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding or soldering is used to attach the protective cover to the base plate, then a strong and hermetic seal is achieved, but the heat input degrades the filling mass and compromises the seal quality
Solution Approach 1:
The filling mass is injected into the cavity before the protective cover is attached to the base plate. This preliminary action ensures the filling mass is in place before any heat-generating operations, preventing heat degradation and contamination of the filling mass while still achieving a hermetic seal through the attachment process.
Solution Approach 2:
The traditional sequence is inverted: instead of attaching the cover first and then injecting filling mass (which would require drilling through the cover and risk contamination), the filling mass is injected first through openings in the base plate, then the cover is attached to seal the cavity hermetically.
2Object-affected harmful factors
If the protective cover is hermetically sealed to the base plate before filling, then contamination is avoided, but the filling mass cannot be properly injected and cured
Solution Approach 1:
The filling mass injection is performed as a preliminary action before the hermetic sealing is completed. Openings are provided in the base plate to allow injection of the filling mass into the cavity, and these openings are subsequently sealed during the attachment process, ensuring both proper filling and hermetic protection.
3Object-affected harmful factors
If magnets are mounted and covered with fibreglass bandage in traditional method, then corrosion protection is provided, but magnets cannot be removed for remagnetization and special tools are required
Solution Approach 1:
The system is segmented into separable components: the protective cover can be detached from the base plate, allowing the magnets to be removed from the cavity for remagnetization if needed, while the hermetic seal and filling mass provide corrosion protection during normal operation.
Solution Approach 2:
The protective cover is designed to be detachably attached to the base plate, providing a dynamic system that can transition from a sealed protective state to an open accessible state for magnet removal and remagnetization operations.
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 method offers superior corrosion and mechanical protection for magnets within a sealed cover, allowing for post-mount magnetization and easy removal in case of demagnetization, while avoiding contamination and heat-related issues in the sealing process.
Implementation Method 1
The interior cavity between the protective cover and the base plate is injected with a filling mass which is then cured. The cured filling mass bonds the protective cover and the base plate to one another.
Implementation Method 2
The interior cavity between the protective cover and the base plate is evacuated.
Data Source
AI summary
A method for manufacturing of a permanent magnet pole piece comprising at least one magnet which is fixed to a base plate, a protective cover and a filling mass is provided, comprising the steps of fixing of the protective cover to the base plate so that it covers the magnet and so that the protective cover and the base plate are hermetically sealed jointed, evacuating of the interior cavity between the protective cover and the base plate through an opening, injecting of the filling mass through an opening into the interior cavity between the protective cover and the base plate and curing of the filling mass.