Stepped Planetary Gear Transmission for Symmetric Power Distribution
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Solution Overview
Problem
Current transmission devices for electric motor vehicles lack an efficient and symmetrically designed solution for distributing drive power to both wheels, particularly in electric axle drives, where existing designs often result in complex and costly configurations.
Innovation Solution
A transmission device incorporating a planetary gear with stepped planetary gears and a spur gear differential transmission, where compensation gears are arranged in phase with stepped planetary gears, allowing for a symmetrical distribution of power through a common planet carrier, enabling efficient torque transmission and rotational speed distribution to both output sun gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional differential mechanism with multiple pinions and reduction gears is used, then power distribution to both wheels is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the differential mechanism and reduction mechanism into a single integrated planetary gear system. The first and second sun gears are integrated with the planetary gears, eliminating the need for separate reduction pinions and carriers. This merging of functions reduces the number of components while maintaining the dual capabilities of power distribution and speed reduction.
Solution Approach 2:
The planetary gears serve multiple functions simultaneously: they act as both the differential mechanism (through the sun gears and planetary gears) and the reduction mechanism (through the same gear meshing). This multi-functionality allows a single compact structure to perform what traditionally required separate differential and reduction mechanisms.
2Ease of operation
If asymmetric differential mechanisms are used for power distribution, then functional requirements are met, but manufacturing precision and cost increase
Solution Approach 1:
The patent employs asymmetric tooth count configurations in the planetary gears to achieve the desired power distribution characteristics. By deliberately designing different numbers of teeth on various gear components, the system optimizes torque distribution and rotational characteristics while maintaining manufacturing feasibility through standardized gear cutting processes.
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 simplifies the transmission device, ensuring efficient power distribution to both wheels, reducing complexity and cost while maintaining symmetry and identical design for both output sun gears, enhancing the electric axle drive performance.
Implementation Method 1
the first gear meshes with the drive sun gear
Implementation Method 2
the second gear meshes with the ring gear
Implementation Method 3
the first compensation gears mesh with the first output sun gear, wherein the second compensation gears mesh with the second output sun gear
Data Source
AI summary
A transmission device for a motor vehicle includes a planetary gearset and a spur gear differential. The planetary gearset includes a drive sun gear, a ring gear fixed to the housing, and multiple stepped planetary gears. Each stepped planetary gear has a first gear meshing with the drive sun gear and a second gear meshing with the ring gear. The spur gear differential includes multiple first and second compensation gears. Each first compensation gear meshes with a first output sun gear, each second compensation gear meshes with a second output sun gear, and the first and second compensation gears mesh with each other in pairs. One compensation gear of each compensation gear pair is arranged in phase with a respective stepped planetary gear. The other compensation gear of each compensation gear pair overlaps axially and contactlessly with the second gear.