Terminal Fitting Reverse Tapered Locking Surface
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Solution Overview
Problem
In reduced-size connectors and terminal fittings, existing locking structures often fail to provide sufficient terminal holding force, and a strong pulling force can displace the retainer, releasing the locking mechanism due to a small engagement margin between upright locking surfaces.
Innovation Solution
The terminal fitting features a reverse tapered retainer locking surface and lance locking surface, both formed after assembly to ensure proper contact and increased surface area, with the retainer locking surface being a non-plated surface to maintain contact and the lance locking surface biting into the locking lance, enhancing the terminal holding force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the connector and terminal fitting are reduced in size with thinned components, then the connector size is reduced, but the terminal holding force becomes insufficient
Solution Approach 1:
The locking surface is changed from a vertical upright surface to a reverse tapered inclined surface. This geometric parameter change allows the locking surface to engage more effectively with the locking protrusion, increasing the holding force through the inclined geometry that converts pulling force into locking force, thereby maintaining sufficient terminal holding force even in reduced-size connectors.
2Volume of moving object
If the engagement margin between upright locking surfaces is small, then the connector size is reduced, but a strong pulling force may displace the retainer and release locking
Solution Approach 1:
The locking surface is changed from vertical to reverse tapered inclined geometry. This parameter change creates a self-locking mechanism where the inclined surface angle and direction are optimized so that pulling force on the terminal fitting is converted into increased engagement force between the locking surface and protrusion, preventing retainer displacement and maintaining reliable locking even with minimal engagement margin.
3Ease of manufacture
If the locking surface is formed before folding, then the manufacturing process is simpler, but the locking surface may not contact the retainer properly due to bending variation
Solution Approach 1:
The locking surface is formed after the folding operation rather than before. This sequence ensures that the locking surface is created on the already-bent component, eliminating the problem of bending variation causing poor contact. The locking surface is then formed precisely at the final position where it will contact the retainer, guaranteeing proper engagement.
4Reliability
If the retainer locking surface is made non-plated, then contact reliability with the retainer is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The terminal fitting has different surface treatments in different regions: the retainer locking surface is non-plated to ensure reliable contact and engagement with the retainer, while other portions of the terminal fitting retain plating for corrosion protection and electrical conductivity. This local differentiation of surface quality optimizes each region for its specific function while managing manufacturing complexity.
Data Source
AI summary
It is aimed to improve a terminal holding force. A terminal fitting includes a terminal connecting portion (12) connectable to a mating terminal fitting, a wire connecting portion (13) disposed behind the terminal connecting portion (12) and to be connected to an end part of a wire, and a retainer locking portion (18) formed to project on the terminal connecting portion (12) and having a retainer locking surface (22) to be locked by a retainer (5). The retainer locking surface (22) is formed into a reverse tapered shape from a projecting end side toward a base end side.