Gear Shift Finger Profile for Reduced Gearbox Vibration
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Solution Overview
Problem
Manual gearboxes experience vibrations due to contact between the control finger and fork, leading to undesirable movements of the gear ratio control knob, and increasing clearance or effort for gear ratio passage are not optimal solutions.
Innovation Solution
A gear ratio change control system with a shaft and fork design featuring convex generatrix surfaces, where the distal section has constant curvature for engaging a gear ratio and the proximal section has a flatter profile to reduce vibrations by maintaining a reduced shift stroke and increasing play in the engaged gear ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If play is introduced or increased between the shift fork and the shift finger, then vibrations are reduced, but the gear shift travel increases
Solution Approach 1:
The invention applies local quality by differentiating the curvature characteristics of different sections of the finger. The distal section has a first curvature radius while the proximal section has a second curvature radius that is 1.5 to 3 times larger, creating localized geometric variations that serve different functional purposes in reducing vibrations versus controlling shift travel.
Solution Approach 2:
The invention changes the geometric parameters of the finger by introducing a curvature radius ratio of 1.5 to 3 between distal and proximal sections. This parameter modification allows the finger to maintain optimal contact characteristics during gear engagement while reducing vibrations, without increasing the overall gear shift travel distance.
2Object-affected harmful factors
If play is introduced or increased between the shift fork and the shift finger, then vibrations are reduced, but the effort required to shift gears increases
Solution Approach 1:
The differentiated curvature sections create local quality variations where the distal section maintains tighter contact for precise gear engagement while the proximal section with larger curvature reduces vibration transmission, achieving vibration reduction without increasing the force required for gear shifting.
Solution Approach 2:
By modifying the curvature radius parameter along the finger length (1.5 to 3 times larger at the proximal section), the invention optimizes the force distribution during gear engagement, reducing vibrations while maintaining acceptable shifting effort levels.
3Object-affected harmful factors
If the finger profile is modified to reduce vibrations, then gear knob vibrations are eliminated, but the manufacturing complexity increases
Solution Approach 1:
The invention implements local quality through differentiated curvature sections on the finger, where only specific regions (distal and proximal sections) have modified geometric properties. This localized approach simplifies manufacturing compared to completely redesigning the entire finger, as the changes are confined to specific zones along the finger length.
Data Source
Figure 1
Figure 2A~5A
Figure 3A~5B
AI summary
Gear ratio shift drive shaft, for a gearbox, the shaft comprising a finger (1103) disposed radially on the shaft (100) for interacting with a fork crosshead, the finger (1103) resting against the fork crosshead for the purposes of coupling or decoupling, by means of two opposing convex generatrix cylindrical surfaces (1103d, 1103e) according to a planar symmetry, and wherein the convex generatrix surfaces (1103d, 1103e) of the finger (1103) have a distal section of constant curvature (1103d) for resting against the fork crosshead when the finger (1103) is rotated to engage a first of the two ratios and a proximal section (1103e) of a profile that is flatter than that of the distal section to provide a space between the corresponding bearing surface of the fork (302) and the finger (1103) after the finger (1103) has been rotated to engage the second of the two ratios.