Terminal Fitting Locking Hole Engagement Margin
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Solution Overview
Problem
The existing terminal fittings have a limited engagement margin between the locking portion and the locking hole, restricting the size reduction of the rectangular tube portion and preventing the formation of a retracted portion over the entire width, which limits the engagement margin and stability.
Innovation Solution
A terminal fitting design featuring a base plate portion, side plate portions, a lid plate portion with a locking hole extending over the entire width, and a retracted portion formed over the entire width to provide a height difference for engagement with the locking projection, along with a posture stabilizing portion to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the retracted portion is formed by cutting and bending the base plate portion, then the locking hole dimension can be reduced, but the formation range in width direction is limited by the side plate portions
Solution Approach 1:
The lid plate portion is divided into a front plate portion and a rear plate portion that are positioned at different heights. The retracted portion is formed only in the rear plate portion, allowing it to extend beyond the side plate portions and achieve full width coverage without interfering with the side plate structure.
Solution Approach 2:
The solution moves the retracted portion formation from the base plate to the lid plate portion, specifically in the rear plate portion. This dimensional relocation allows the retracted portion to achieve full width coverage by extending beyond the side plate portions, resolving the width direction limitation.
2Reliability
If the retracted portion is limited to the formation range within side plate portions, then the structure remains simple, but the engagement margin between locking lance and locking hole is limited
Solution Approach 1:
The lid plate portion is segmented into front and rear plate portions at different heights. The retracted portion is formed only in the rear plate portion, allowing it to extend beyond the side plate portions and achieve full width coverage, thereby maximizing the engagement margin without requiring complex modifications to the entire structure.
Solution Approach 2:
The retracted portion is selectively formed only in the rear plate portion of the lid plate, which is the specific location needed to maximize engagement margin. This localized formation achieves the reliability improvement without requiring the entire structure to be redesigned.
3Reliability
If the locking hole opening range extends from front end to rear end of locking projection, then the engagement margin is maximized, but the rectangular tube portion length increases
Solution Approach 1:
The rear plate portion is positioned at a different height than the front plate portion, creating a stepped configuration. The retracted portion in the rear plate allows the locking hole to engage the locking projection effectively while reducing the overall length of the rectangular tube portion, as the locking engagement occurs at the elevated rear plate level.
Solution Approach 2:
By forming the retracted portion in the rear plate portion at a different height, the locking engagement is achieved in a different dimensional space. This allows the locking hole to maintain adequate engagement margin with the locking projection while reducing the forward-backward length of the rectangular tube portion.
Data Source
Figure 1
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Figure 4
AI summary
An object of the present invention is to ensure a large engagement margin between a locking lance and a locking hole. A rectangular tube portion 10 of a terminal fitting T includes a lid plate portion 16 extending substantially at a right angle from the extending end edge of a right side plate portion 15 and formed with a locking hole 20 extending over the entire width, a front plate portion 19F extending in a cantilever manner from the right side plate portion 15 and arranged before the locking hole 20, a rear plate portion 19R extending in a cantilever manner from the right side plate portion independently of the front plate portion 19F and arranged to be behind and adjacent to the locking hole 20, and a retracted portion 21 formed over the entire width at the rear plate portion 19R, retracted inwardly of the rectangular tube portion 10 from the front plate portion 19F to provide a height difference within the range of an engagement margin with a locking projection 34 and capable of facing a rear end part of the locking projection 34.