Coaxial EV Powertrain Layout for Compact Multi-Speed Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing powertrains for heavy-duty electric vehicles, such as trucks and buses, require shiftable transmissions for efficient power transfer, but existing solutions are not compact or cost-effective.
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 compact packaging and multiple gear states, including a differential gearset for improved 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 multiple gear states, but the device complexity and packaging space requirements increase
Solution Approach 1:
The patent combines multiple planetary gearsets (first and second planetary gearsets) with reduction gearsets into a single integrated transmission unit. The first planetary gearset and second planetary gearset are coaxially arranged and mechanically coupled through reduction gearsets, allowing the system to achieve at least four different gear states while occupying a compact space. This merging approach reduces the number of separate components and simplifies the overall structure compared to using multiple independent gear systems.
Solution Approach 2:
The transmission system employs a nested arrangement where the first planetary gearset is positioned upstream and the second planetary gearset is positioned downstream, with reduction gearsets interconnecting them in a compact sequence. The gearsets are arranged such that they occupy overlapping or adjacent spaces along the rotational axis, creating a nested configuration that minimizes the overall length and packaging volume while maintaining the complexity needed for multiple gear states.
2Productivity
If multiple planetary gearsets and reduction gearsets are arranged in sequence, then favorable speed ratios are achieved, but the extension of the powertrain along the rotational axis increases
Solution Approach 1:
Instead of arranging all gearsets in a simple linear sequence along the rotational axis, the patent uses a combination of axial and radial arrangements. The first planetary gearset and second planetary gearset are coaxially arranged, and the reduction gearsets are positioned to connect them in a compact configuration that utilizes three-dimensional space more efficiently. This dimensional optimization reduces the overall extension along the rotational axis while maintaining the necessary speed reduction stages.
3Volume of moving object
If a compact transmission arrangement is designed, then packaging space is reduced, but the ease of manufacture and assembly may be compromised
Solution Approach 1:
The transmission system is divided into distinct modular segments: the first planetary gearset, the reduction gearsets, and the second planetary gearset. Each segment can be manufactured and assembled separately, then integrated into the final compact configuration. This segmentation approach allows for standardized manufacturing of individual components while achieving a compact overall arrangement when assembled together, balancing manufacturing ease with space efficiency.
Data Source
AI summary
A powertrain for a vehicle has a first power unit, a first primary reduction gearset, a first planetary gearset, 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, a second planetary gearset, 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, preferably two half-shafts.