Breaker Movable Piece Arc-Shaped Narrow Portion
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Solution Overview
Problem
Conventional breakers face challenges in miniaturization due to increased stress on thermally actuated elements when thicker movable pieces are used, leading to potential damage and deformation during repeated operations, while also requiring low electrical resistance for improved secondary battery performance and faster charging times.
Innovation Solution
A breaker design featuring a movable piece with a cantilevered, elastically deformable elastic portion that includes a first narrow portion with an arc-shaped contour, reducing bending rigidity and stress concentration, allowing for decreased electrical resistance without enlarging the case size and preventing damage to the thermally actuated element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the movable piece is increased to decrease conduction resistance, then electrical resistance decreases, but stress on the thermally actuated element increases causing damage during repeated operation
Solution Approach 1:
The movable piece is designed with non-uniform thickness: the elastic portion has a first thickness that is smaller than the second thickness of other portions. This local variation in thickness allows the movable piece to have sufficient overall strength while reducing stress concentration on the thermally actuated element during operation.
Solution Approach 2:
The patent changes the thickness parameter of the movable piece at different locations. By making the elastic portion thinner than other portions, the design optimizes the balance between electrical resistance (requiring sufficient thickness) and stress reduction (benefiting from thinner sections), thereby resolving the contradiction.
2Reliability
If a thermally actuated element with large diagonal length is used to suppress damage, then reliability improves, but case size increases hindering miniaturization
Solution Approach 1:
Instead of uniformly increasing the size of the thermally actuated element, the patent applies local quality optimization by varying the thickness of the movable piece. This allows stress reduction without requiring a larger thermally actuated element, thus maintaining compact case dimensions while improving reliability.
3Reliability
If the movable piece is made thicker to reduce contact resistance, then electrical performance improves, but the breaker cannot be miniaturized
Solution Approach 1:
The movable piece features localized thickness variation where the elastic portion is thinner than other portions. This allows the breaker to achieve good electrical performance through sufficient thickness in contact areas while maintaining miniaturization through reduced thickness in the elastic portion, optimizing both electrical performance and size.
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 solution effectively decreases electrical resistance during energization and prevents damage to the movable piece, enabling miniaturization of the breaker while maintaining durability and efficient operation.
Implementation Method 1
a thermally actuated element which deforms in accordance with a temperature change
Implementation Method 2
a movable piece having a plate-shaped and elastically deformable elastic portion
Data Source
AI summary
A breaker includes a fixed piece having a fixed contact, a movable piece having an elastically deformable elastic portion and a movable contact formed at a tip portion of the elastic portion and pushed to contact with the fixed contact, a thermally actuated element deformable according to a temperature change to shift the state of the movable piece from a conductive state to a cut-off state, and a case accommodating the fixed piece, the movable piece, and the thermally actuated element. The movable piece is cantilevered by the case on a base end portion side of the elastic portion, the elastic portion includes a first narrow portion having a smaller width dimension in a short direction perpendicular to a longitudinal direction of the elastic portion than the base end portion, and the first narrow portion has an arc-shaped contour in plan view from a thickness direction of the elastic portion.