EV Drive Unit Gear Layout With Axial Load Canceling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electric vehicle drive units lose efficiency and require unnecessary housing size and weight due to the conventional method of splitting electric motor torque into opposing output paths via an input differential.
Innovation Solution
The electric vehicle drive unit incorporates an input differential that splits the torque into two paths, which are then received by first and second pinion gear shaft assemblies. These assemblies are configured in a concentric and radially stacked arrangement, with opposed helix hands on the pinion gears to cancel axial loads, and engage with a first stage transfer gear assembly for speed reduction, followed by a second stage gear assembly for further speed reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor torque is split into opposing output paths via an input differential, then the torque distribution is achieved, but the housing size and weight increase unnecessarily
Solution Approach 1:
The patent combines the two pinion gear shaft assemblies into a single integrated unit with concentric and radially stacked arrangements. The first pinion gear shaft assembly and second pinion gear shaft assembly are merged such that they share common housing space and structural support, eliminating the need for separate housing sections and reducing overall housing weight while maintaining torque distribution functionality.
Solution Approach 2:
The patent implements a nested configuration where the first pinion gear shaft assembly is positioned concentrically within or adjacent to the second pinion gear shaft assembly. The pinion gears are arranged in a nested fashion where inner components are surrounded by outer components, allowing multiple torque paths to coexist in a compact volume, thereby reducing housing size and weight without compromising torque distribution capability.
2Ease of operation
If the electric motor torque is split into opposing output paths via an input differential, then the torque distribution is achieved, but the housing size increases unnecessarily
Solution Approach 1:
The patent merges the spatial requirements of two separate pinion gear assemblies into a single integrated structure. By combining the housing sections and sharing common structural elements, the overall housing footprint is reduced while maintaining the necessary torque distribution paths.
Solution Approach 2:
The patent transitions from a conventional lateral arrangement of pinion gear assemblies to a three-dimensional concentric and radially stacked configuration. This dimensional reorganization allows the torque paths to be stacked vertically and radially rather than extending horizontally, significantly reducing the housing's planar area while preserving torque distribution functionality.
3Device complexity
If conventional pinion gear assemblies are used without load canceling, then the structure is simpler, but gear and bearing loads increase
Solution Approach 1:
The patent applies load canceling principles where the first pinion gear and second pinion gear are configured to generate opposing axial loads that counterbalance each other. The helical pinion gears are arranged with opposite hand orientations, creating equal and opposite axial forces that cancel out, thereby reducing the net load on bearings and housing without requiring additional counterbalancing components.
Solution Approach 2:
The patent employs asymmetric configuration of the pinion gears with opposed helix hands. While the overall structure maintains symmetry for balance, the individual gear elements use asymmetric helical orientations to generate canceling axial loads, optimizing the force distribution across the gear and bearing system.
4Force
If the pinion gears have opposed helix hands to cancel axial loads, then the gear and bearing loads are minimized, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the pinion gear assembly into separate first and second pinion gear shaft assemblies, each with its own pinion gear. This segmentation allows each gear to be manufactured independently with standard helical gear processes, and then assembled in the correct opposing orientations. The segmentation simplifies manufacturing by avoiding the need to machine complex opposed-helix features into a single monolithic gear component.
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
This configuration achieves efficient torque distribution, minimizes gear and bearing loads, and reduces the overall size and weight of the drive unit while maintaining high efficiency and eliminating bending loads on motor pinion shafts.
Implementation Method 1
the first pinion gear and the second pinion gear have opposed helix hands canceling axial loads of the first pinion gear and the second pinion gear
Implementation Method 2
A first stage speed reduction is achieved by meshing the first pinion gear with the first transfer gear and the third transfer gear, and by meshing the second pinion gear with the second transfer gear and the fourth transfer gear
Implementation Method 3
the first pinion gear shaft assembly and the second pinion gear shaft assembly are configured in a concentrically and radially stacked arrangement
Data Source
AI summary
An electric vehicle drive unit includes an electric motor generating a torque. An input differential splits the torque into a first torque created by a first side gear and a second torque created by a second side gear. A first pinion gear shaft assembly receives the first torque and has a first pinion gear. A second pinion gear shaft assembly receives the second torque and has a second pinion gear. A first stage transfer gear assembly has a first, a second, a third, and a fourth transfer gear. A first stage speed reduction meshes the first pinion gear with the first transfer gear and the third transfer gear, and meshes the second pinion gear, the second transfer gear and the fourth transfer gear. A second stage gear assembly engages the first stage transfer gear assembly and includes a first final drive gear and a second final drive gear.