Vehicle Earthing Terminal Locking to Prevent Cross-Threading
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Solution Overview
Problem
Existing earthing point systems for motorized vehicles are prone to failure due to cross-threading issues during assembly and loosening from vibrations, compromising the reliability and ease of attachment.
Innovation Solution
A device comprising a fixing bolt with a base, middle, and head section, a planar terminal with locking projections, and a nut that locks without a threaded screw arrangement, using a ledge and projections to secure the terminal and prevent rotation, ensuring a stable and vibration-resistant connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threaded nut and screw arrangement is used to secure the terminal to the fixing bolt, then the terminal can be firmly attached, but cross-threading issues occur during assembly and the connection loosens due to vibrations
Solution Approach 1:
The patent removes the threaded screw arrangement from the system entirely. Instead of using a nut that screws onto threads, the invention uses a simple nut that slides over a smooth cylindrical middle section of the fixing bolt and is retained by a ledge, eliminating cross-threading issues and assembly difficulties while maintaining secure attachment.
Solution Approach 2:
Rather than using threads to create friction-based engagement, the patent inverts the approach by using a ledge structure that provides mechanical retention through geometry rather than threading. The nut is retained by the ledge formed between the head section and middle section, creating a positive mechanical lock that prevents loosening from vibrations.
2Reliability
If a threaded nut and screw arrangement is used to secure the terminal, then the terminal can be firmly attached, but the assembly process becomes more complex and time-consuming
Solution Approach 1:
The patent removes the threaded screw arrangement from the system entirely. Instead of using a nut that screws onto threads, the invention uses a simple nut that slides over a smooth cylindrical middle section of the fixing bolt and is retained by a ledge, eliminating cross-threading issues and assembly difficulties while maintaining secure attachment.
3Device complexity
If the terminal is mounted on the fixing bolt without anti-rotation features, then the assembly is simpler, but the terminal rotates and compromises the electrical connection
Solution Approach 1:
The patent uses asymmetric geometric features to prevent rotation. The base section of the fixing bolt has a non-circular cross-section that matches a corresponding feature on the terminal, creating a key-way like structure. This asymmetric interface allows simple assembly while effectively preventing rotation and maintaining reliable electrical connection.
Data Source
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AI summary
A device for providing an earthing point of a motorised vehicle, the device comprising a fixing bolt, a terminal and a nut. The fixing bolt is configured to be mounted on a body of the motorised vehicle. The fixing bolt comprises a base section for attaching to the vehicle body, a middle section providing a shaft from the base section and a head section having a cross sectional area which is greater than the middle section to form a ledge between the underside of the head section and the middle section. The terminal provides one or more electrical connections to be earthed, and includes a hole for the terminal to be mounted on the base section of the fixing bolt. The nut has a hole which is large enough for the nut to pass over the head section of the fixing bolt, and has an axial depth which corresponds with an axial depth of the middle section of the fixing bolt. The terminal and the base section of the fixing bolt are configured to prevent the terminal, when mounted on the base section of the fixing bolt, from rotating. One of the base section of the fixing bolt and the terminal includes a plurality of projections arranged in a two dimensional plane. The nut and the plurality of projections are configured so that, when the nut is mounted on the fixing bolt to rotate about the middle section with a surface of a first side of the nut engaging with one of the base section of the fixing bolt or the terminal and another other side of the nut being constrained by the ledge formed between the head section and the middle section of the fixing bolt, the plurality of projections arranged in the two dimensional plane provide an unlocked state in which the nut is free to rotate about the middle section until a surface of the other end of the nut is forced by the plurality of projections against the ledge of the head section to secure the nut and the terminal when the nut is in a locked position by the nut being constrained by the ledge of the head section and the plurality of projections.