Planetary EV Transmission Layout for Wide Ratios and Lower Loss
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Solution Overview
Problem
Existing transmissions for electric vehicles, particularly heavy-duty vehicles like trucks and construction equipment, lack a compact and efficient design that can provide favorable speed ratios and reduce energy losses.
Innovation Solution
A transmission arrangement comprising multiple planetary gearsets and reduction gearsets, configured to be shiftable between different gear states, allowing for compact and efficient power transfer between electric motors and drive wheels, with optional neutral states to reduce energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission arrangement with multiple planetary gearsets is used, then the speed ratio range and driving efficiency are improved, but the device complexity increases
Solution Approach 1:
The patent combines two planetary gearsets (first and second planetary gearsets) with a common carrier axis into a single integrated transmission arrangement. The first planetary gearset includes sun gear, planet gears, and ring gear, while the second planetary gearset includes sun gear, planet gears, and ring gear, all sharing a common rotational axis. This merging approach enables multiple speed ratios (direct gear state with 1:1 ratio and speed reduction gear states) without requiring separate transmission units, thus improving adaptability while controlling complexity.
Solution Approach 2:
The transmission arrangement is designed to provide multiple functions through a single integrated structure. The first and second planetary gearsets can independently operate in direct gear state (1:1 speed ratio) or speed reduction gear state, allowing the system to achieve various speed ratios and torque multiplication effects. The common carrier architecture enables universal power transmission path while maintaining flexibility in gear state selection, improving versatility without proportionally increasing structural complexity.
2Volume of moving object
If the speed reduction ratio of the first secondary reduction gearset is reduced, then the transmission arrangement becomes more compact, but the manufacturing precision requirements increase
Solution Approach 1:
The patent segments the speed reduction function into two distinct planetary gearsets rather than using a single high-ratio reduction stage. The first planetary gearset handles initial speed reduction while the second planetary gearset provides additional reduction. This segmentation allows each gearset to operate at moderate reduction ratios, reducing the size of individual gearwheels and overall transmission volume, while distributing manufacturing precision requirements across multiple components rather than concentrating them in one complex gearset.
Solution Approach 2:
The patent arranges the first and second planetary gearsets in series along the power transmission path, utilizing the axial dimension for compact layout. Both gearsets share a common carrier axis, allowing them to be stacked or arranged along the rotational axis rather than requiring lateral space. This dimensional arrangement reduces the overall volume of the transmission arrangement while maintaining functional separation between the two reduction stages, and facilitates standardized manufacturing of each gearset module.
Data Source
AI summary
A transmission arrangement for a vehicle. comprising a first planetary gearset, a first secondary reduction gearset. a second planetary gearset, and at least one drive shaft. The disclosure also relates to a powertrain and a vehicle.