Leaf Spring Stress-Relief Structure for IGBT Mounting Reliability
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Solution Overview
Problem
Conventional IGBT spring elements are prone to mechanical failures due to stress concentration and high displacement at critical sections, leading to increased maintenance costs and reduced service life.
Innovation Solution
The IGBT spring element incorporates strategically disposed stress relieving sections in the form of cutouts and straight sections to prevent stress concentrations and displacements, ensuring a gradual change in cross-sections and enhanced stiffness, thereby reducing the likelihood of mechanical failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the leaf spring is made with uniform width and simple structure, then the manufacturing is easy and device complexity is low, but stress concentration and mechanical failure occur at critical sections
Solution Approach 1:
The leaf spring is designed with non-uniform width where the width varies along the length of the spring. Specifically, the width is greater at sections远离 the fixed end and smaller at sections closer to the fixed end. This local variation in geometry distributes stress more evenly throughout the spring structure, preventing stress concentration at critical sections while maintaining manufacturing feasibility through standard fabrication processes.
2Force
If the leaf spring extends angularly from the body to increase urging pressure, then the effectiveness in holding elements together is improved, but displacement and stress at critical sections increase leading to mechanical failure
Solution Approach 1:
The leaf spring incorporates varying width sections that create localized stiffness variations. The wider sections provide greater flexibility and stress distribution capacity, while narrower sections provide appropriate rigidity. This gradient in local properties allows the spring to maintain effective urging pressure through its angular extension while distributing stresses to prevent mechanical failure.
Solution Approach 2:
The leaf spring design incorporates curved or angular geometry rather than simple straight extensions. This curved configuration allows the spring to achieve the necessary urging pressure through distributed deformation along its length, reducing stress concentration at any single critical section while maintaining the required force application to the held elements.
3Strength
If the leaf spring is designed with abrupt cross-section changes to achieve desired stiffness, then the structural efficiency is improved, but stress concentration occurs leading to mechanical failure
Solution Approach 1:
Instead of abrupt cross-section changes, the leaf spring employs gradual width variations along its length. This progressive change in local geometry creates smooth transitions in stiffness properties, maintaining structural efficiency for load bearing while eliminating the stress concentration that would occur at sharp geometric discontinuities. The gradual transition allows stress to distribute evenly across the spring structure.
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 design modification significantly reduces the chances of mechanical failure, enhances the reliability and service life of the IGBT spring element, and simplifies its construction and usage.
Implementation Method 1
The at least one leaf spring exerts a predetermined urging pressure on an element disposed between the body and the housing as the body is mounted on the housing
Data Source
AI summary
A spring element includes a body, at least one leaf spring and a stress relieving section. The body includes at least one mounting section. The leaf spring includes a first portion and a second portion. The first portion being secured to the body and at least a part thereof extends angularly with respect to a plane of the body. The leaf spring exerts an urging pressure on an element disposed between the body and a housing as the body is mounted on the housing. The stress relieving section is formed along at least one lateral side of the leaf spring and proximal to the first portion.