Terminal Fitting Lock-Hole Structure to Prevent Positional Deviation

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Solution Overview

Problem

Conventional engagement structures of terminal metal fittings and housings fail to prevent positional deviation of terminal metal fittings, leading to improper electrical contact and potential disengagement due to biting and external forces during wiring.

Innovation Solution

The opening area of the lock hole is increased by cutting and erecting the surrounding portion, allowing a larger lock projection that can withstand deeper biting, and utilizing the space between the lock hole and terminal spring to receive the lock projection, thereby suppressing positional deviation and enabling miniaturization of the terminal metal fitting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the terminal metal fitting is pulled by an electric wire during wiring, then the terminal metal fitting may be pressed against the lace and cause biting, but this leads to positional deviation and improper electrical contact

Engineering Contradiction:

Improveelectrical contact reliabilityVSAvoidbiting force from electric wire

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful biting force into a beneficial locking mechanism. The lock hole is designed to receive the lace, and when the terminal metal fitting is pulled during wiring, the end surface of the lock hole bites into the lace, creating a firm engagement that prevents the fitting from coming loose. This transforms the potentially harmful pulling force into a secure locking action that ensures reliable electrical contact.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Manufacturing precision

If the opening area of the lock hole is increased to allow a larger lock projection, then positional deviation is suppressed, but the internal space of the box portion is reduced

Engineering Contradiction:

Improvepositional accuracy of terminal metal fittingVSAvoidinternal space of box portion

Core Design Contradiction:

Manufacturing precisionVSVolume of stationary object

Solution Approach 1:

The patent utilizes the depth dimension of the lock hole to accommodate the lace, rather than solely relying on the width or height dimensions. By designing the lock hole with sufficient depth and an optimized opening area, the patent allows the lace to extend into the lock hole and be engaged by the end surface, thereby suppressing positional deviation without significantly reducing the overall internal space of the box portion.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If the terminal metal fitting is miniaturized to reduce housing size, then productivity is improved, but the ability to withstand biting force is reduced

Engineering Contradiction:

Improvehousing miniaturizationVSAvoidresistance to biting force

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent employs a composite structure combining the lock hole, lace, and lock projection into an integrated engagement system. The lock hole is formed with specific dimensional characteristics (opening area and depth) that work in conjunction with the lace material properties to distribute and withstand the biting force. This composite engagement mechanism allows the terminal metal fitting to be miniaturized while maintaining sufficient strength to resist pulling forces during wiring.

Inventive Principle:

Principle #40Composite materials

4Volume of moving object

If the space between the lock hole and terminal spring is used to receive the lock projection, then the terminal metal fitting can be miniaturized, but the terminal spring may interfere with the lock projection

Engineering Contradiction:

Improvesize of terminal metal fittingVSAvoidinterference between terminal spring and lock projection

Core Design Contradiction:

Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent segments the internal space of the box portion into distinct functional zones. The space between the lock hole and terminal spring is specifically allocated for receiving the lock projection, while the terminal spring is positioned and dimensioned to operate within its own zone without interfering with the lock projection. This spatial segmentation allows the terminal metal fitting to be miniaturized while preventing harmful interference between components.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP3588688B1Terminal metal fitting and engagement structure of terminal metal fitting and housing

Publication Date: 2023.12.13 YAZAKI CORP

Figure 1A~1B
Figure 2
Figure 3A~3B

AI summary

A terminal metal fitting (10) includes a tubular box portion (11) receiving a counterpart terminal; a lock hole (14) formed through a wall (11a) of the box portion (11) and receiving the lock projection (25); a terminal spring (16) extending from an inner wall surface of the box portion (11) to press and contact to the counterpart terminal; and a supporting point portion (15) formed at a portion around the lock hole (14) to have a cantilevered-shape. The supporting point portion (15) serves as a supporting point (15a) when the terminal spring (16) contacts to the counterpart terminal.