Earthing Nut Thread Geometry for Reliable Conduction
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Solution Overview
Problem
Existing earthing nuts with partial deformation portions for conduction often result in irregular contact with bolts, leading to poor fastening force and fluctuating earthing performance due to irregular shapes and incomplete conduction states.
Innovation Solution
The earthing nut design features a screw thread pitch deviation (Pn = P + α) and angle (θ = 60 + β) to ensure high-pressure contact and reliable conduction, with cut-outs on both sides of the axial direction to peel off coating films and provide a sealing material to prevent water infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deformation portion is partially provided in a screw portion to achieve conduction, then a conduction state can be achieved between the earthing nut and bolt, but the fastening force becomes poor because the screw portion is unlikely to contact the bolt at portions other than the deformation portion
Solution Approach 1:
The invention applies local quality by providing cut-outs only at specific positions (both ends or one end) of the screw hole rather than throughout the entire screw portion. This localized approach allows coating film peeling and conduction at critical contact points while preserving the integrity and fastening capability of the remaining screw thread structure.
Solution Approach 2:
The screw hole is segmented by introducing cut-outs that divide the continuous screw thread into distinct sections. This segmentation creates discrete contact zones for coating removal and electrical conduction, while the uncut portions maintain structural strength and fastening functionality.
2Reliability
If the deformation portion is formed by applying external force to decrease diameter, then conduction can be achieved, but the deformation portion likely has an irregular shape causing fluctuation in conduction state and irregular earthing performance
Solution Approach 1:
The cut-outs are pre-formed in the screw hole at designated positions before the earthing nut is assembled to the bolt. This preliminary preparation ensures that when the bolt is threaded through, the coating film is reliably peeled at these predetermined locations, achieving consistent conduction states without relying on irregular deformation during assembly.
Solution Approach 2:
The invention changes the geometric parameters of the screw hole by introducing cut-outs with specific dimensions and positions (both ends or one end). This parametric modification creates controlled geometry for coating removal and conduction, replacing the irregular shape problem with precisely defined structural features.
3Reliability
If cut-outs are provided on both sides in axial direction, then coating film can be peeled more effectively and conduction state improved, but the structural strength of the screw hole may be reduced
Solution Approach 1:
The invention applies partial action by providing cut-outs at only the critical locations (both ends or one end of the screw hole) rather than continuously throughout the entire screw portion. This selective approach removes coating film where it most affects conduction while minimizing the total material removed, thereby preserving the overall structural strength of the screw hole.
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
This design achieves a strong fastening force and stable conduction state between the earthing nut and bolt, ensuring reliable electrical connectivity without compromising the nut's strength, even at low fastening torque, and allows for the use of a single type of general-purpose bolt.
Implementation Method 1
The screw thread pitch is set to be different from the screw thread pitch of the bolt by a predetermined value, and the screw thread angle is set to be different from the screw thread angle of the bolt by a predetermined value
Implementation Method 2
the cut-outs are provided on both sides in the axial direction... to peel off coating films
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An earthing nut 11 according to the present invention, in which a fastening force is great and a conduction state can be reliably achieved with respect to a bolt 33, includes a screw hole 22 that is engaged with the bolt 33 in which screw threads 21 are formed at a pitch P. In all screw threads 21 provided in the screw hole 22, a pitch Pn of the screw thread 21 is greater than the pitch P of the screw thread 21 of the bolt 33, and an angle θ [degrees] of the screw thread 21 is formed to be greater than 60 degrees. In a portion of the screw hole 22 in an axial direction, a cut-out 25 is provided extending in the axial direction, and an end surface of the screw thread 21 facing the cut-out 25 forms a cutting edge 26.