Canted Coil Spring Terminal Fitting for Automotive Connectors
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Solution Overview
Problem
Existing methods for establishing electrical connections in automotive applications, such as those described in Japanese Patent Laid-Open No. 2002-274290, face challenges with contamination removal due to increased stiffness of thicker leaf springs required for large currents, leading to inadequate elastic deformation and contact resistance.
Innovation Solution
A terminal fitting utilizing a canted coil spring with an inclined wound surface, sandwiched between a mating terminal and an electrical contact member, which resists elasticity to deform and rub off contamination when the terminals connect, ensuring effective contact despite contamination presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker leaf spring is used for large current, then current carrying capacity is improved, but elastic deformability deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the coil spring by introducing a cant angle (inclination of the wound surface relative to the coil axis). This parameter modification allows the spring to achieve both high current carrying capacity and sufficient elastic deformability, as the cant angle creates a mechanical advantage that amplifies the rubbing motion during contact while maintaining structural integrity for large currents.
Solution Approach 2:
The patent transitions from a conventional straight coil spring to a canted coil spring by adding a dimensional feature (the cant angle). This dimensional change introduces a new degree of freedom in the spring's deformation behavior, enabling it to simultaneously satisfy both the current carrying requirement and the contamination removal requirement through enhanced rubbing motion.
2Reliability
If a thicker leaf spring is used for large current, then current carrying capacity is improved, but contamination removal capability deteriorates
Solution Approach 1:
By modifying the geometric parameter (cant angle) of the coil spring, the patent enhances the rubbing motion between contacting surfaces. This parameter change allows the spring to effectively remove contamination while maintaining the thickness required for large current transmission, thus resolving the contradiction between current carrying capacity and contamination removal capability.
Solution Approach 2:
The introduction of the cant angle dimension transforms the spring's contact mechanics, creating a more effective rubbing action that removes contamination. This dimensional modification enables the spring to simultaneously handle large currents and effectively clean contact surfaces, eliminating the trade-off present in conventional designs.
3Object-affected harmful factors
If a canted coil spring is used instead of a leaf spring, then contamination removal capability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the winding geometry of the coil spring (introducing the cant angle) while keeping the overall spring structure and material properties similar to conventional springs. This localized modification achieves enhanced contamination removal capability without substantially increasing device complexity, as the change is confined to the spring's geometric configuration rather than requiring additional components or complex mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The canted coil spring design effectively removes contamination and maintains contact pressure, reducing contact resistance and parts count while accommodating large currents without significant changes in spring load, ensuring reliable electrical continuity.
Implementation Method 1
the canted coil spring resists its elasticity and deforms in such a manner that the wound surface inclines farther. Through this process, in a contact portion between the canted coil spring and the contact surface of the mating terminal and a contact portion between the canted coil spring and the facing surface of the electrical contact member, a shifted movement phenomenon occurs in such a manner that the canted coil spring rubs each surface.
Data Source
AI summary
A terminal fitting (10) includes an electrical contact (20) with a facing surface (21) facing a contact surface (81) of a mating terminal (80). A canted coil spring (50) that is made of a conductive wire material (51) has a wound surface inclined with respect to the coil axis (L) of the canted coil spring (60). The coil axis (L) is parallel with the facing surface (21) of the electrical contact member (20). The canted coil spring (50) is sandwiched between the mating terminal (80) and the electrical contact member (20) when the mating terminal (80) and the electrical contact member (20) approach each other. A holder shaft (40) is inserted in the canted coil spring (50) to hold the canted coil spring (50) in a posture where the coil axis L is parallel with the facing surface (21) of the electrical contact member (20).