Connector Fitting Body Stepped Bolt Nut Housing Protection
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Solution Overview
Problem
Conventional connector fitting bodies with tightening-type fitting structures face challenges in managing bolt tightening torque, which can lead to damage of resin-based housings due to excessive axial force, especially when a large number of terminals are used or higher contact strength is required.
Innovation Solution
The connector fitting body design incorporates a bolt with a stepped head that presses the first housing toward the second housing, and a nut with a corresponding step that receives the second housing, ensuring that the axial force from tightening does not compress the housings directly, allowing for easier management of tightening torque and protection from damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large tightening torque is applied to tighten the bolt for ensuring contact strength of terminals, then the contact strength of male terminals and female terminals is improved, but the axial force applied to the resin housing increases causing damage risk
Solution Approach 1:
A metal plate is introduced as an intermediary component between the bolt and the resin housing. The metal plate receives the axial force from the bolt head and transfers it to the housing, preventing direct compression of the resin material. This allows large tightening torques to be applied without damaging the housing, thereby maintaining both high contact strength and housing integrity.
Solution Approach 2:
The invention changes the material parameter of the interface between bolt and housing from resin (low strength) to metal plate (high strength). By replacing the resin contact surface with a metal plate, the system can withstand higher axial forces and tightening torques without exceeding the strength limits of the housing material.
2Object-affected harmful factors
If the bolt tightening torque is limited to protect the resin housing, then the housing damage is prevented, but the contact strength of terminals cannot be sufficiently ensured
Solution Approach 1:
The metal plate serves as a mediator that decouples the relationship between bolt tightening torque and housing stress. It allows the bolt to apply high tightening forces while the housing only experiences distributed, manageable pressures through the metal plate's larger contact area and higher strength properties.
Solution Approach 2:
The contact interface is segmented into two distinct zones: a high-stress zone between the bolt and metal plate where large forces are transmitted, and a low-stress zone between the metal plate and housing where forces are distributed. This segmentation allows each interface to be optimized for its specific function.
3Device complexity
If a conventional tightening structure is used where the bolt head contacts the housing directly, then the structure is simple, but the bolt mounting portion made of resin may be damaged due to axial force
Solution Approach 1:
A metal plate is positioned between the bolt head and the resin housing to prevent direct contact. This simple addition of one component protects the resin mounting portion from axial force damage while maintaining overall structural simplicity and ease of assembly.
Data Source
AI summary
A connector fitting body (1) has a first housing (2) holding first terminals (21), a second housing (3) holding second terminals (31) to be conductive with the first terminals (21), a nut (5) arranged in a nut arrangement hole (32) in the second housing (3), and a bolt (4) arranged in a bolt arrangement hole (22) in the first housing (2) and engaged threadedly with the nut (5). A head (41) of the bolt (4) includes a large-diameter portion (411) serving as a first step for pressing the first housing (2) toward the second housing (3). The nut (5) includes a general portion (51) serving as a second step for pressing the second housing (3) toward the first housing (2). An end surface of the head (41) is in contact with an end surface of the nut (5).