Wire Harness Terminal Insertion via Insulator Thinning
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Solution Overview
Problem
Existing methods for preventing corrosion in connecting portions between electric wire conductors and terminals often result in terminals being unable to be smoothly inserted into connector housings due to oversized resin coatings, leading to increased manufacturing costs and potential electrical connection issues.
Innovation Solution
A connecting structure where the terminal is crimped only to the exposed conductor of the electric wire, with the insulator coating being thinned to allow the coating resin to fit within standard terminal insertion holes, ensuring smooth insertion and enhanced waterproof properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mold resin is used to coat the end connecting portion to prevent corrosion, then corrosion prevention is improved, but the outer diameter becomes larger than the terminal insertion hole inner diameter
Solution Approach 1:
The insulator is divided into two functional zones: a first insulator portion that is stripped to expose the conductor for terminal connection, and a second insulator portion that remains coated with mold resin for corrosion protection. This segmentation allows selective application of resin only where needed, preventing excessive outer diameter increase.
Solution Approach 2:
The mold resin coating is applied locally only to the second insulator portion adjacent to the conductor exposed portion, rather than uniformly across the entire insulator. This localized coating provides corrosion protection at the critical connecting portion while maintaining a smaller overall outer diameter that fits within the terminal insertion hole.
2Ease of operation
If the terminal insertion hole is enlarged to accommodate the resin-coated terminal, then insertion is facilitated, but the connector housing size increases and manufacturing cost rises
Solution Approach 1:
By segmenting the insulator into stripped and coated portions, the design enables the terminal to be inserted into standard-sized holes without modification, eliminating the need for enlarged connector housings and reducing manufacturing costs.
Solution Approach 2:
The outer diameter parameter of the coated portion is controlled by limiting resin application to only the second insulator portion, ensuring it remains smaller than the standard terminal insertion hole inner diameter, thus maintaining compatibility with existing connector housings.
3Length of moving object
If the insulator coating is thinned to reduce outer diameter, then insertion into standard holes is enabled, but the insulator strength may be reduced
Solution Approach 1:
The insulator is segmented such that the first portion is stripped and the second portion retains full or reduced thickness coating. This segmentation allows the coated second portion to provide sufficient mechanical strength and corrosion protection while the overall outer diameter is reduced for insertion compatibility.
Solution Approach 2:
The insulator thickness is optimized locally: the second insulator portion has sufficient thickness to maintain strength and provide effective corrosion protection, while the overall configuration ensures the outer diameter remains smaller than the terminal insertion hole, avoiding the need for uniform thinning that would compromise strength.
Data Source
Figure 1A~1F
Figure 2A~2C
Figure 3A~3F
AI summary
An objective of the present invention is to provide a connecting structure, a connecting device, and a connecting method for electric wires and terminals which allow terminals connected to electric wire conductors to be smoothly inserted into terminal insertion holes of connector housings, and a wire harness. For coating a connecting portion 6 of a conductor 3 of an electric wire 2 and a terminal 5, which form a wire harness 1, with a coating resin 7, a portion of an insulator 4, which is to be inserted into a terminal insertion hole 9 of a connector housing 8, is subjected to a diameter reduction process such that an outer diameter of the coating resin 7 coated on the insulator 4 is smaller than the terminal insertion hole 9. Therefore, for inserting the terminal 5 of the wire harness 1 into the terminal insertion hole 9 of the connector housing 8, an outer peripheral surface of the coated resin 7 coated on the connecting portion of the conductor 3 of the electric wire 2 and the terminal 5 does not abut the inlet side peripheral portion of the terminal insertion hole 9, and the terminal 5 of the wire harness 1 can be smoothly inserted into the terminal insertion hole 9 of the connector housing 8.