Transmission Arrangement With Coupled Planetary Gears
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Solution Overview
Problem
Existing gear arrangements for electric vehicle drive trains are complex due to the need for the drive to be routed through a hollow shaft, requiring a complex design to output to the first wheel axle, which complicates the integration of a compact e-axle module.
Innovation Solution
The integration of a first planetary gear set with a structurally connected ring gear to the rotor of the electric machine, allowing for a compact e-axle design by eliminating the need for a differential gear, with two coupling variants between the first and second planetary gear sets that support torques and achieve fixed ratios less than 1, enabling a differential gear-free E-axle module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the drive is routed through the sun wheel to the hollow shaft, then the transmission can be achieved, but the design becomes complex and requires routing outwards within the hollow shaft
Solution Approach 1:
The patent inverts the conventional routing path by driving the first wheel axle directly from the planet carrier instead of routing through the sun wheel and hollow shaft. This reversal eliminates the need for complex internal routing within the hollow shaft structure.
Solution Approach 2:
The patent extracts the drive path from the conventional sun wheel → hollow shaft route and redirects it through the planet carrier → first wheel axle path. This extraction removes the requirement for routing through the hollow shaft, simplifying the overall design.
2Adaptability or versatility
If a differential gear is included in the e-axle module, then the wheel speed differences can be accommodated, but the module size and complexity increase
Solution Approach 1:
The planet carrier serves multiple functions: it acts as both the drive output to the first wheel axle and the structural support for the planetary gears. This multi-functionality eliminates the need for a separate differential gear mechanism while maintaining adaptability to wheel speed differences.
Solution Approach 2:
The patent merges the differential function into the planetary gear set structure itself, where the planet carrier naturally accommodates wheel speed variations. This combining of functions removes the need for an additional differential gear component.
3Ease of manufacture
If the ring gear and rotor are separate components, then manufacturing flexibility is maintained, but assembly complexity and connection requirements increase
Solution Approach 1:
The patent combines the ring gear and rotor into a single integrated component. This merging eliminates the need for separate manufacturing and assembly operations, reducing connection requirements while maintaining manufacturing flexibility through integrated design.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a transmission arrangement (10) with a first planetary gear stage (18) and with a second planetary gear stage (20). The transmission arrangement (10) is driven by a rotor (14) of an electric machine (12). The first planetary gear stage (18) comprises a first sun gear (40), and the second planetary gear stage (20) comprises a second sun gear (42). Stepped planet gears (28, 34) of the first planetary gear stage (18) mesh with the first sun gear (40), whereas planet gears (48, 50) of the second planetary gear stage (20) mesh with the second sun gear (42). In the transmission arrangement (10) according to the invention, the first sun gear (40) of the first planetary gear stage (18) is coupled to the second sun gear (42) of the second planetary gear stage (20) via a coupling shaft (26), or alternatively, a planetary carrier (44) of the first planetary gear stage (18), on which the stepped planet gears (28, 34) of the first planetary gear stage (18) are held, is connected to a second internal gear (58) of the second planetary gear stage (20), with which the planet gears (48, 50) of the second planetary gear stage (20) mesh.