Stator Core Locking via Plate Spring Key
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Solution Overview
Problem
Existing methods for locking a stator core to a housing in electric motors or generators, such as press-fitting a tapered pin, can cause deformation or breakage of key grooves and fail to provide sufficient length to withstand shearing forces, leading to increased manufacturing costs and stress on the key grooves.
Innovation Solution
A locking structure using a plate spring key with a U-shaped longitudinal section, which applies a spring force to cut-outs in the stator core and housing, reducing stress on the key grooves and providing sufficient shearing resistance without the need for complex machining or additional locking processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tapered pin is press-fitted into the key hole, then the key can be locked in place, but the key grooves may be deformed or broken down due to wedge effect
Solution Approach 1:
The key is designed with a tapered shape where the width at the insertion end is smaller than the width at the other end. This parameter change allows the key to be inserted first at the narrower end into the key groove, and then expanded against the bottom surface of the key groove to provide locking force, avoiding concentration of stress at a single point while maintaining reliable locking
Solution Approach 2:
The key employs a curved or tapered geometry rather than a straight cylindrical shape. The tapered configuration allows gradual insertion and expansion, distributing the locking force along the length of the key groove rather than concentrating it at one location, thereby reducing the risk of groove deformation or breakage
2Ease of manufacture
If only a tapered portion is used in the key, then insertion is easier, but it is difficult to obtain sufficient key length to tolerate shearing force
Solution Approach 1:
The key combines both a tapered portion and a straight portion in a single integrated structure. The tapered portion facilitates easy insertion into the key groove, while the straight portion extends the effective length of the key to provide sufficient resistance against shearing forces. These two functional sections work together to satisfy both insertion ease and strength requirements
Solution Approach 2:
The key is divided into distinct functional segments: a tapered insertion end that facilitates easy entry into the key groove, and a straight portion that provides the necessary length for withstanding shearing forces. This segmentation allows each part to optimize its specific function while contributing to the overall performance of the locking mechanism
3Strength
If a straight portion is added to the tapered portion in the key, then shearing force resistance improves, but key length and manufacturing cost increase
Solution Approach 1:
The tapered portion and straight portion are merged into a single monolithic key structure rather than being separate components. This integration maintains the functional benefits of both sections (easy insertion from the tapered end and shearing force resistance from the straight portion) while avoiding the complexity of assembling multiple parts, thereby controlling manufacturing complexity and cost
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 plate spring key design reduces stress on the key grooves, lowers manufacturing costs, and effectively prevents the key from falling off, while providing a strong holding force and shearing resistance to secure the stator core to the housing.
Implementation Method 1
The key comprises a plate spring that applies a spring force to at least one of the first and second cut-outs
Implementation Method 2
providing sufficient shearing resistance without the need for complex machining or additional locking processes
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A stator core having a circular outer circumference is locked to an inner circumferential surface of a cylindrical housing. A first groove is formed in the outer circumference of the stator core, and a second groove is formed in the inner circumference of the housing. A plate spring is used as a key that is interposed between the first and second grooves so as to apply a spring force to at least one of the first and second grooves. This construction reduces the stress that occurs in the key grooves due to insertion of the key.