Dual-Clutch Torque Transfer for Electrified Vehicle Powertrains
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Solution Overview
Problem
Electrified vehicle powertrains face challenges in efficient torque transfer between engines and electric machines, particularly in starting the engine with minimal torque from the electric machine, which affects reserve torque availability for driving wheels.
Innovation Solution
A dual-clutch system is implemented, where a first disconnect clutch transfers torque from the engine to the electric machine, and a second disconnect clutch, with a gear reduction system, transfers torque from the electric machine to the engine for starting, allowing reduced torque requirements and reserve torque management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single clutch is used to transfer torque from the electric machine to the engine for starting, then the engine can be started, but the torque capacity required from the clutch is high and reserve torque for wheel driving is reduced
Solution Approach 1:
The patent divides the single clutch function into two separate clutches: a first clutch for transferring torque from engine to electric machine, and a second clutch for transferring torque from electric machine to engine for starting. This segmentation allows each clutch to be optimized for its specific function with appropriate torque capacity, reducing the burden on any single clutch and preserving reserve torque for wheel driving.
2Power
If a gear reduction system is added to the second clutch, then the torque required from the electric machine for engine starting is reduced, but the device complexity increases
Solution Approach 1:
The patent introduces a gear reduction system as an intermediary mechanism between the electric machine and the engine through the second clutch. This gear system provides torque multiplication, allowing the electric machine to start the engine with reduced torque output. The gear reduction acts as a mediator that transforms the torque characteristics to match the starting requirement.
3Ease of operation
If the first clutch is used for engine starting, then the engine can be started, but the reserve torque available for driving the wheels is reduced
Solution Approach 1:
The patent segments the clutch functions so that the first clutch (with higher torque capacity) handles torque transfer from engine to electric machine, while the second clutch (with lower torque capacity and gear reduction) handles torque transfer from electric machine to engine for starting. This segmentation ensures that the first clutch is not burdened with starting duties, preserving its availability for wheel driving operations and maintaining reserve torque.
Data Source
AI summary
An electrified vehicle torque transfer system includes, among other things, an engine having an engine shaft, an electric machine having an electric machine shaft, a first clutch that is selectively engaged to rotatably couple together the engine shaft and the electric machine shaft such that the engine can drive rotation of the electric machine, and a second clutch that is selectively engaged to rotatably couple together the engine shaft and the electric machine shaft such that the electric machine can drive rotation of the engine.