EV Differential Backlash Control With Elastic Side Gear Support
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Solution Overview
Problem
Existing differential apparatuses for electric vehicles fail to maintain a consistent backlash in the differential gear, leading to noise generation due to hard contact between the side and pinion gears when the vehicle is driven in 2WD mode, especially under high-speed rotation conditions.
Innovation Solution
Incorporation of a pinion shaft supporter with elastic members, such as wave washers, to provide an elastic force that maintains the initial backlash of the differential gear, preventing the side gears from being pushed inward by axial forces and ensuring consistent spacing between the side and pinion gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spacers are applied between the differential case and side gears to secure backlash, then the differential gear backlash is maintained during assembly, but the backlash increases and decreases during actual vehicle driving due to axial forces and temperature changes
Solution Approach 1:
The patent applies elastic members (wave washers) that can elastically deform in the axial direction to compensate for changes in backlash caused by axial forces and temperature variations. The elastic deformation capability allows the system to maintain consistent backlash under varying operating conditions.
Solution Approach 2:
The elastic members are pre-installed between the pinion shaft supporter and side gears to provide beforehand cushioning against axial forces. This pre-cushioning mechanism prevents direct transmission of axial forces to the differential gear, maintaining stable backlash during vehicle operation.
2Device complexity
If no elastic members are used, then the structure is simple, but the side gear is pushed inward by axial force causing hard contact between side gear and pinion gear, generating differential noise
Solution Approach 1:
The elastic members act as intermediary elements between the pinion shaft supporter and side gears. These intermediaries absorb axial forces through elastic deformation, preventing direct force transmission that would cause hard contact and noise between the side gear and pinion gear.
Solution Approach 2:
The elastic members provide beforehand cushioning by being pre-installed in the axial direction to counteract axial forces before they can push the side gear inward. This prevents hard contact and the resulting differential noise during high-speed rotation in 2WD mode.
3Use of energy by moving object
If the disconnector system is released in 2WD mode, then fuel efficiency is improved, but high-speed rotation of the differential gear causes axial force that reduces backlash and generates noise
Solution Approach 1:
The elastic members are pre-installed to provide beforehand cushioning against axial forces generated during high-speed rotation in 2WD mode. This cushioning mechanism maintains backlash stability even when the disconnector system is released for improved fuel efficiency, preventing noise generation.
Solution Approach 2:
The elastic members utilize elastic deformation parameter changes to compensate for axial force effects. As axial forces vary during high-speed rotation, the elastic members deform accordingly to maintain consistent backlash, preventing noise while allowing fuel-efficient 2WD operation.
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 solution effectively prevents differential noise by maintaining the initial backlash, ensuring smooth operation and reducing noise generation during high-speed rotations in 2WD mode.
Implementation Method 1
elastic members respectively disposed between first and second lateral sides of the pinion shaft supporter and the respective internal sides of the support plates to provide an elastic force in the axial direction to the pair of side gears
Data Source
AI summary
A differential apparatus for an electric vehicle includes a differential case disposed between driveshafts, a pinion shaft disposed in the differential, at least two pinion gears rotatably coupled on each side of the pinion shaft, and a pair of side gears disposed in a direction perpendicular to the pinion gears, the differential apparatus includes a pinion shaft supporter disposed on the pinion shaft between the pinion gears within the differential case, support plates on first and second sides thereof which are friction-supported by contacting respective internal surfaces of the pair of side gears and facing respective lateral sides of the pinion shaft supporter, and elastic members respectively disposed between first and second lateral sides of the pinion shaft supporter and the respective internal sides of the support plates to provide an elastic force in the axial direction to the pair of side gears.