Permanent Magnet Rotor Casing for Electric Drive Motors
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Solution Overview
Problem
Existing electric drive motors in household appliances, such as refrigeration and washing machines, face inefficiencies due to increased air gaps caused by the use of hardened plastic or adhesive materials for fixing permanent magnets, which limits mechanical stability and efficiency, especially at high speeds or with ferrite magnets.
Innovation Solution
A non-magnetic casing made of sheet steel or stainless steel encloses the permanent magnets to counteract centrifugal forces, reducing the air gap and enhancing mechanical stability and efficiency without altering magnetic field lines, and is secured through a press fit and adhesive bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If permanent magnets are fixed with hardened plastic material, then mechanical stability is improved, but air gap increases and efficiency decreases
Solution Approach 1:
The patent removes the hardened plastic material from the rotor assembly, extracting only the essential function of mechanical stability. This elimination of the plastic material directly reduces the air gap between rotor and stator, thereby improving efficiency while maintaining structural integrity through alternative means (precise rotor yoke design and magnetic bonding).
Solution Approach 2:
The patent changes the material parameter from hardened plastic to a combination of precise mechanical fitting and magnetic bonding. This parameter change allows the permanent magnets to be securely fixed without adding significant thickness, thus maintaining small air gap and high efficiency while achieving adequate mechanical stability.
2Loss of energy
If permanent magnets are fixed with adhesive layers, then efficiency is maintained, but mechanical stability is insufficient for high-speed machines
Solution Approach 1:
The patent employs a composite approach combining adhesive bonding with precise mechanical fitting of the rotor yoke. This composite fixation method leverages the strengths of both approaches: adhesives provide adequate bonding for efficiency, while the precision-machined rotor yoke structure provides the mechanical stability required for high-speed operation, creating a synergistic solution.
3Stability of the object's composition
If fiberglass epoxy bandage is used to fix permanent magnets, then mechanical stability is improved, but air gap increases and efficiency decreases
Solution Approach 1:
The patent eliminates the fiberglass epoxy bandage entirely, extracting only the necessary mechanical support function which is provided by the precisely engineered rotor yoke structure. This removal of the bandage material prevents air gap increase, thereby maintaining efficiency while achieving mechanical stability through superior precision engineering.
Solution Approach 2:
The patent replaces the mechanical bandage system with a precision-machined rotor yoke system. The rotor yoke incorporates precisely fitted surfaces and structural features that provide mechanical stability without requiring additional binding materials, thus avoiding air gap increase and maintaining high efficiency.
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 configuration reduces the air gap between the rotor and stator, increasing the efficiency of the electric machine, extending its service life, and allowing for a compact, cost-effective design suitable for high-output applications.
Implementation Method 1
an electric machine designed as an electric drive motor (102)... a rotor (204) which has a rotatably mounted rotor yoke (208) and a plurality of permanent magnets (302)
Implementation Method 2
a centrifugal force acting on the plurality of permanent magnets during a rotation of the rotor yoke
Data Source
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AI summary
The invention relates to an electrical machine, in particular an electric drive motor, having a rotor (204) which has a rotatably mounted rotary yoke (208) and also a plurality of permanent magnets (302) which are arranged on an outer surface (300) of the rotor yoke (208). According to the invention, a casing (400) surrounds the plurality of permanent magnets (302) in order to at least partially compensate for a centrifugal force which can act on the plurality of permanent magnets (302) when the rotor yoke (208) rotates.