Transmission Pinion Backlash Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical transmissions experience backlash due to gear geometry and tolerances, leading to undesirable noise, vibration, and harshness (NVH) issues, especially when reversing rotational direction, which is exacerbated in vehicles using electric motors for torque vectoring.
Innovation Solution
A transmission design incorporating a first gear, a shaft, a second gear, and a biasing member, where the second gear is fixedly coupled to the shaft and axially slidable to engage the first gear, and a second output member that can move relative to the first output member to adjust tooth spacing, utilizing a biasing member to maintain engagement and reduce backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional fixed gear meshing is used, then structural simplicity is maintained, but backlash occurs causing noise and vibration during load cycling and direction reversal
Solution Approach 1:
The patent applies dynamics by making the second gear axially movable along the shaft rather than fixed. The second gear can slide axially to maintain continuous contact with the first gear, eliminating backlash. This dynamic adjustment allows the gear system to adapt to load changes and direction reversals, preventing the harmful effects of backlash while maintaining reasonable structural complexity through a single degree of freedom movement.
2Adaptability or versatility
If electric motor is used for torque vectoring, then vehicle maneuverability is improved, but frequent direction changes exacerbate backlash and NVH issues
Solution Approach 1:
The patent ensures continuity of useful action by maintaining constant meshing contact between the first and second gears through the axial movement capability of the second gear. During frequent direction changes enabled by electric motor torque vectoring, the second gear continuously adjusts its axial position to eliminate backlash, ensuring uninterrupted torque transmission and preventing NVH issues that would otherwise occur during direction reversal.
3Object-affected harmful factors
If gear tolerances are tightened to reduce backlash, then backlash is reduced, but manufacturing cost and complexity increase
Solution Approach 1:
The patent applies parameter changes by introducing axial movement as a new degree of freedom for the second gear. Instead of relying solely on tight manufacturing tolerances to control backlash, the system changes the operational parameter of the second gear from fixed position to variable axial position. This allows standard tolerance gears to achieve backlash-free operation through dynamic adjustment, avoiding the need for expensive high-precision manufacturing.
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 design effectively reduces backlash-related NVH by maintaining constant contact between gear teeth, allowing for smooth torque transfer and improved operational stability across rotational directions.
Implementation Method 1
The first biasing member can bias the third gear axially away from the second gear and into engagement with the first gear
Implementation Method 2
The first biasing member can bias the second output member toward the second position and into engagement with the second set of teeth
Data Source
AI summary
A transmission can include a first gear, a shaft, a second gear, a third gear and a first biasing member. The first gear can be disposed about a first rotational axis. The shaft can be disposed about a second rotational axis. The second gear can be fixedly coupled to the shaft and can be configured to meshingly engage the first gear. The third gear can be non-rotatably coupled to the shaft. The third gear can be axially slidable along the shaft and can be configured to meshingly engage the first gear. The first biasing member can bias the third gear axially away from the second gear and into engagement with the first gear.