Sprung Web Clamping Element for Internal Rotor Magnet Security
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Solution Overview
Problem
Existing internal rotor electric motors face challenges in securely fastening permanent magnets, leading to potential rattling or falling out due to rebound of clamping mechanisms over the motor's lifespan, especially under high acceleration and impact conditions, requiring additional components and complex designs that increase costs and complexity.
Innovation Solution
The design incorporates a laminated rotor core with first and second recesses and a web-shaped clamping element that applies a radially outward spring force to the rotor magnets, ensuring secure clamping through elastic deformation and minimizing material strain, thus preventing rebound and maintaining magnet position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional clamping methods (gluing, retaining washers, embedding in synthetic resin) are used to secure permanent magnets, then the magnets can be firmly held in the laminated core, but additional work steps, time, and auxiliary materials are required
Solution Approach 1:
The clamping function is merged into the laminated core structure itself through the web-shaped clamping element that is integrally formed with the core. This eliminates the need for separate clamping components and reduces manufacturing steps while maintaining secure magnet holding.
Solution Approach 2:
The web-shaped clamping element automatically exerts clamping force on the permanent magnets through its elastic deformation when the rotor rotates. The system serves itself by using the rotational motion to generate the necessary clamping force without additional actuators or complex mechanisms.
2Reliability
If sprung pressing (notching, imprinting) is used to clamp permanent magnets radially inward, then the magnets are initially secured in recesses, but the pressing can spring back over the useful life of the motor causing magnets to become loose and rattle
Solution Approach 1:
The web-shaped clamping element is designed to dynamically adapt to the rotational motion of the rotor. As the rotor rotates, the element experiences cyclic elastic deformation that maintains continuous clamping force on the magnets, preventing springback and ensuring long-term clamping stability.
Solution Approach 2:
The geometric parameters of the web-shaped clamping element (thickness, width, curvature) are optimized to provide sufficient elastic deformation capacity. This allows the element to undergo repeated deformation cycles without permanent set, maintaining consistent clamping force throughout the motor's operational life.
3Reliability
If high clamping forces are applied to secure magnets firmly, then the magnets remain firmly held under high acceleration, but high tensile stresses occur in the laminated core
Solution Approach 1:
The web-shaped clamping element concentrates the clamping force locally at the magnet-clamping interface while distributing the stress across the broader laminated core structure. This localized approach provides strong magnet holding without subjecting the entire core to high tensile stresses.
Solution Approach 2:
The solution utilizes the composite nature of the laminated core structure, where multiple thin laminations work together to provide both the elastic compliance needed for clamping and the overall structural strength to withstand the clamping forces without excessive stress.
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 solution provides a secure and reliable holding mechanism for rotor magnets, reducing noise and the risk of magnet loss, while simplifying the design and reducing material strain, thus enhancing motor performance and durability under various operational conditions.
Implementation Method 1
a sprung web-shaped clamping element (291) is formed between a second recess (231) and an associated first recess (211), which clamping element is tensioned by an associated rotor magnet (221) towards the second recess (231)
Data Source
AI summary
An internal rotor for an electric motor has a laminated rotor core with a multiplicity of rotor plates, and multiple pockets in each of which pocket a rotor magnet is at least partially arranged. The rotor plates have first recesses for forming the pockets and at least a first rotor plate which has at least a second recess associated with a first recess. A sprung web-shaped clamping element is formed between the second recess and the associated first recess, and tensioned toward the second recess by the associated rotor magnet to apply a force to the associated rotor magnet toward the first recess in order to hold the associated rotor magnet in the pocket. A rotor plate holds a rotor magnet in a pocket of a laminated rotor core.