Adjustable Connecting Rod Key Lock Against Vibration Misadjustment
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Solution Overview
Problem
Existing connecting rods with adjustable length suffer from misadjustment due to vibrations and have a bulky, mass-intensive anti-rotation system, particularly when the diameter is large, which increases on-board mass.
Innovation Solution
A connecting rod design featuring a key with distinct parts that immobilize the first fixing head relative to the body, utilizing a key with a blade and notches for secure rotation prevention, decoupling the anti-rotation system's volume and mass from the rod's diameter, ensuring stable length adjustment without bulkiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locknut is used as the anti-rotation system, then the connecting rod length can be adjusted, but the locknut can unscrew due to vibrations causing misadjustment and the locknut becomes bulky and mass-intensive for large diameter rods
Solution Approach 1:
The anti-rotation system is segmented into a key with distinct parts: a first part engaging the body, a second part engaging the fixing head, and a third part connecting them. This segmentation allows each part to be optimized independently, reducing overall mass while maintaining anti-rotation security against vibrations.
Solution Approach 2:
The third part of the key acts as an intermediary element connecting the first part (engaging the body) and the second part (engaging the fixing head). This intermediary structure distributes forces and provides a stable connection without requiring a bulky locknut, thereby reducing mass while ensuring reliable anti-rotation.
2Reliability
If a locknut is used as the anti-rotation system, then the connecting rod length can be adjusted, but the locknut can unscrew due to vibrations causing misadjustment
Solution Approach 1:
The key is divided into three functional parts that work together to prevent rotation: the first part engages the body, the second part engages the fixing head, and the third part connects them. This segmented design provides multiple engagement points that resist vibrational forces more effectively than a single locknut, improving length adjustment stability.
Solution Approach 2:
The traditional locknut mechanism is replaced with a key-based system that uses geometric engagement (faces pressed against surfaces, notches fitting together) rather than friction-based thread locking. This substitution provides more reliable anti-rotation performance under vibration while maintaining structural efficiency.
3Reliability
If the anti-rotation system is designed to be secure against vibrations, then misadjustment is limited, but the system becomes bulky and mass-intensive
Solution Approach 1:
The key is divided into three functional parts that work together to prevent rotation: the first part engages the body, the second part engages the fixing head, and the third part connects them. This segmented design provides multiple engagement points that resist vibrational forces more effectively than a single locknut, improving length adjustment stability.
Solution Approach 2:
Each part of the key is designed with specific local geometries optimized for its function: the first part has a face for pressing against the body's outer surface, the second part includes a blade for pressing against the plate's face, and the third part provides planar faces for connecting components. This localized optimization achieves secure connection with minimal volume.
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a connecting rod comprising a body (12), first and second fixing heads (14, 18) provided at each end (12.1, 12.2) of the body (12) and connected by first and second linking systems (24) to first and second elements, the first fixing head (14) comprising an extension screwing into a housing of the body (12) to adjust the length of the connecting rod (10). According to the invention, the connecting rod (10) includes an anti-rotation system (38) comprising a key (40), positioned astride the first fixing head (14) and the body (12), which has a first part (42) cooperating with the body (12) so as to be immobilized in rotation relative to the body (12) and a second part (44) cooperating with the first fixing head (14) and the first linkage system (24) so as to be immobilized relative to the first fixing head (14).