Motorcycle Transmission Input Shaft Adjustment for Gear Backlash
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Solution Overview
Problem
Motorcycle drive devices face challenges in adjusting the backlash between gear wheels due to thermal expansion differences between steel and aluminum components, leading to noise sensitivity and inadequate adjustment ranges.
Innovation Solution
An adjustable backlash mechanism using an eccentric shaft and bearing plates with deep-groove ball bearings allows for precise adjustment of the axial spacing between the primary pinion and transmission input shaft axes, enabling a durable and mistake-proof connection to maintain optimal gear meshing angles and reduce noise sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If gear wheels and housing are made of different materials (steel/aluminum) to achieve weight reduction, then weight is reduced, but thermal expansion differences cause temperature-dependent backlash variations
Solution Approach 1:
The patent changes the physical state of the adjustment mechanism by using a bearing plate that can be positioned at different axial locations. This allows the backlash parameter to be adjusted compensating for thermal expansion differences between steel gear wheels and aluminum housing, maintaining reliable meshing conditions across temperature variations.
2Object-affected harmful factors
If gear pairs have slight meshing angle to reduce noise, then noise is reduced, but the adjustment range for backlash becomes inadequate
Solution Approach 1:
The patent introduces an additional degree of freedom by allowing the bearing plate to be positioned at different axial locations, not just radial adjustments. This extra dimensional adjustment capability provides sufficient backlash adjustment range even for gear pairs with slight meshing angles, while maintaining low noise operation.
3Reliability
If axial spacing between gear axes is adjusted to compensate for thermal expansion, then backlash stability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the transmission housing into a fixed housing portion and a movable bearing plate portion. This segmentation allows the bearing plate to be independently positioned at different axial locations to adjust backlash, while the rest of the housing remains simple and unchanged, minimizing overall device complexity.
4Ease of operation
If deep-groove ball bearings are used to mount the transmission input shaft, then ease of adjustment is improved, but manufacturing precision requirements increase
Solution Approach 1:
The deep-groove ball bearings automatically accommodate slight misalignments and positioning variations through their inherent design characteristics. The bearing's ability to self-align and absorb dimensional tolerances reduces the stringency of manufacturing precision requirements while maintaining ease of adjustment capability.
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 mechanism effectively adjusts the backlash to predetermined nominal values, enhancing the operating behavior and durability of the motorcycle drive device by minimizing noise and ensuring accurate power transmission.
Implementation Method 1
The transmission input shaft is mounted in a transmission input shaft bearing, in particular in a deep-groove ball bearing
Implementation Method 2
The motorcycle drive device has an adjusting mechanism for changing the position of the bearing plate with respect to the transmission housing
Implementation Method 3
The different materials (steel/aluminum) have different coefficients of thermal expansion, which results in a temperature dependency of the backlash, since gear wheels and housing expand differently
Data Source
AI summary
A motorcycle drive device includes a shiftable transmission set up to transmit drive power which can be provided by an engine crankshaft toward a drivable wheel. The transmission includes an input shaft having a rotation axis when is displaceable to adjust a spacing between the rotation axes of a primary gearwheel on the transmission input shaft and a primary pinion transferring the drive power from the crankshaft. A transmission input shaft bearing supporting the transmission input shaft is arranged in a bearing plate that is rotatable relative to a housing of the transmission. The bearing plate includes an adjusting mechanism arranged to change the position of the bearing plate with respect to the transmission housing to adjust the axial spacing of the rotation axes.