Coaxial Electric Vehicle Powertrain With Compact Multi-Gear Layout
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Solution Overview
Problem
Existing powertrains for heavy-duty electric vehicles, such as trucks and buses, require shiftable transmissions for efficient power transfer, but these are not always necessary for electric vehicles, leading to a need for improved, compact, and efficient powertrain designs.
Innovation Solution
A powertrain design featuring a first and second power unit, primary and secondary reduction gearsets, and planetary gearsets arranged coaxially with a common rotational axis, allowing for shifting between multiple gear states and compact packaging, including differential and stator arrangements for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a shiftable transmission is used in heavy-duty electric vehicles, then driving efficiency is improved through favorable speed ratios, but device complexity increases
Solution Approach 1:
The patent combines two planetary gearsets (first and second planetary gearsets) into a single integrated transmission unit sharing a common carrier and coaxial arrangement. This merging reduces the number of separate components and simplifies the overall structure while maintaining the ability to provide multiple speed ratios through selective engagement of different gear elements.
Solution Approach 2:
The dual planetary gearset configuration enables the transmission to perform multiple functions within a single device: it can operate in direct gear mode (1:1 ratio) or speed reduction modes through different planetary gear states. The first and second planetary gearsets can be independently controlled to provide various speed ratios, making the transmission adaptable to different driving conditions without requiring separate transmission systems.
2Productivity
If multiple reduction gearsets and planetary gearsets are arranged in sequence, then favorable speed ratios are achieved, but the extension along the rotational axis increases
Solution Approach 1:
The patent implements a nested arrangement where the first planetary gearset and second planetary gearset are positioned coaxially with shared rotational axes. The gearsets are arranged such that components of one gearset are positioned within or adjacent to components of the other, allowing multiple speed reduction stages to be compacted along the radial direction rather than extending sequentially along the axial direction.
Solution Approach 2:
Instead of arranging reduction gearsets in a linear sequence along the rotational axis (one-dimensional arrangement), the patent transitions to a coaxial multi-layer arrangement where gearsets are stacked along the radial dimension. This dimensional change allows multiple speed reduction stages to be accommodated within a shorter axial length by utilizing the radial space around the common rotational axis.
3Volume of moving object
If a compact powertrain arrangement is implemented, then packaging is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple reduction functions into a single integrated transmission housing containing both planetary gearsets. By combining the first and second planetary gearsets into one compact unit with shared components and coaxial arrangement, the overall powertrain volume is reduced while the internal complexity is managed through unified design rather than separate assemblies.
Data Source
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AI summary
The disclosure relates to a powertrain (100) for a vehicle (1), comprising: - a first power unit (P1), - a first primary reduction gearset (210), - a first planetary gearset (310), shiftable between at least two gear states, comprising a direct gear state with a 1:1 speed ratio and a speed reduction gear state, - a first secondary reduction gearset (410), - a second planetary gearset (500), shiftable between at least two gear states, comprising a direct gear state with a 1:1 speed ratio and at least one speed reduction gear state, and - at least one drive shaft (610, 620), preferably two half-shafts (610, 620).