Intermediate Shaft Bearing Layout for Compact Electric Axle Gears
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gear assemblies for electric axles face challenges in balancing bearing fatigue life and achieving a compact design due to uneven load distribution and tolerance stack-ups, leading to increased noise and reduced efficiency.
Innovation Solution
The proposed drive unit configuration relocates the bearing supporting the intermediate shaft closer to the first driven gear, with a second bearing positioned at the distal end, reducing the distance between bearings and improving load balance, allowing for a more compact and efficient gear assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bearing is positioned conventionally in the gear assembly, then the structure is simpler and easier to manufacture, but the bearing fatigue life becomes unbalanced and noise increases
Solution Approach 1:
The bearing position is predetermined and optimized during the design phase to be located between the first driven gear and second drive gear on the intermediate shaft. This preliminary positioning ensures that the bearing is placed at the optimal location before manufacturing, which balances the load distribution and fatigue life without requiring complex adjustments during assembly or operation
2Object-generated harmful factors
If the bearing is relocated closer to the first driven gear with reduced distance between bearings, then load distribution improves and noise reduces, but the manufacturing and assembly precision requirements increase
Solution Approach 1:
The bearing is positioned at a specific location between the first driven gear and second drive gear, creating a localized optimization of load distribution. This local quality improvement at the bearing position reduces noise and vibration in that specific area without requiring high precision throughout the entire gear assembly, as the bearing location itself is optimized for load balance
3Volume of moving object
If the bearing distance between components is reduced, then the gear assembly becomes more compact, but the tolerance stack-up control becomes more difficult
Solution Approach 1:
The bearing position is predetermined in the design phase to be located between the first driven gear and second drive gear, which optimizes the axial distance and enables a more compact gear assembly. This preliminary action establishes the bearing location before manufacturing, allowing for better control of tolerance stack-up by setting fixed reference points for the bearing positions
4Productivity
If conventional bearing positioning is used, then assembly is easier, but uneven load distribution occurs leading to reduced efficiency
Solution Approach 1:
The bearing is positioned at a specific location between the first driven gear and second drive gear, creating localized optimization of load distribution. This improves efficiency by ensuring even load distribution at the critical bearing position, while the bearing location itself serves as a clear assembly reference that maintains ease of operation
Data Source
AI summary
Bearings (72, 74) are arranged for a drive unit (10) having an electric motor for providing drive to an electric axle and a wheel assembly of a vehicle. The drive unit includes a pair of bearings and a reduction gear assembly (12) with a first drive gear mounted to and coaxial with the main shaft of the motor, and a first driven gear rotatably coupled to the first drive gear and mounted to and coaxial with an intermediate shaft to form an intermediate shaft assembly. The reduction gear assembly includes a second drive gear mounted to and coaxial with the intermediate shaft, and a second driven gear rotatably coupled with the second drive gear. A first bearing of said pair of bearings is mounted to a bulkhead and to said intermediate shaft assembly between the first driven gear and second drive gear to reduce the distance between the first and second bearings.