Two-Planetary Hybrid Transmission Mode Switching Under Component Limits
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Solution Overview
Problem
Current multi-mode hybrid transmission systems face challenges in achieving optimal fuel efficiency and performance while maintaining component limits, particularly in transitioning between different operational modes.
Innovation Solution
A multi-mode, power-split hybrid transmission system comprising two planetary gear sets, two electric motors, and various clutches and brakes, allowing for selective operation in modes such as electric drive, power-split, parallel hybrid, and electronic continuously variable transmission, optimized by a supervisory controller to balance fuel economy, acceleration, and mode switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gear sets and torque transfer devices are used to achieve multi-mode operation, then adaptability and versatility are improved, but device complexity increases
Solution Approach 1:
The transmission system is divided into two independent planetary gear sets (first and second), each capable of providing different gear ratios. This segmentation allows the system to achieve multiple operating modes (direct drive, first gear ratio, second gear ratio) by selectively engaging different components, thereby improving adaptability while managing complexity through modular design.
Solution Approach 2:
The clutch device and brake device are designed as multi-functional components that can selectively connect or ground different members of the planetary gear sets. These universal components enable the system to switch between multiple operating modes (series hybrid, parallel hybrid, electric vehicle modes) without requiring separate mechanisms for each mode, thus improving versatility while controlling device complexity.
2Use of energy by moving object
If series hybrid mode is used at low speeds, then fuel economy is improved, but power output may be limited
Solution Approach 1:
The control system dynamically switches between series hybrid mode and other operating modes based on real-time vehicle speed and power demand. At low speeds, the system operates in series hybrid mode for optimal fuel economy, while automatically transitioning to parallel hybrid or direct drive modes when higher power output is required, thus resolving the contradiction between fuel economy and power output through dynamic adaptation.
Solution Approach 2:
The system changes operational parameters by engaging different clutch and brake configurations to switch between operating modes. When transitioning from series hybrid mode to parallel hybrid mode, the control system adjusts the engagement state of torque transfer devices to connect the internal combustion engine directly to the drivetrain, thereby increasing power output while maintaining fuel efficiency through parameter-based mode selection.
3Power
If parallel hybrid mode is used for high power demand, then power output is improved, but fuel consumption increases
Solution Approach 1:
The control system employs periodic switching between series hybrid mode and parallel hybrid mode based on varying power demands. During periods of high power demand, parallel hybrid mode is engaged to provide maximum power output. During periods of lower demand, the system transitions to series hybrid mode to reduce fuel consumption, thus resolving the contradiction through periodic adaptation to changing operational conditions.
4Adaptability or versatility
If multiple torque transfer devices are selectively engaged, then operational flexibility is improved, but control complexity increases
Solution Approach 1:
The control system continuously monitors vehicle operating conditions (speed, power demand, battery state) and uses feedback to automatically select the optimal operating mode. This feedback mechanism simplifies control complexity by automating the decision-making process for engaging clutch and brake devices, allowing the system to achieve operational flexibility through intelligent control rather than complex mechanical switching mechanisms.
Data Source
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AI summary
A multi-mode, power-split hybrid transmission system having two planetary gear (PG) sets connected to one engine, two electric motors, one output shaft, and each other by several clutches, brakes, and direct connection elements. Depending on the specific location and actuation of the various clutch and brake elements, the multi-mode, power-split hybrid transmission system can be run in one of several modes (e.g. electric drive, power-split, parallel hybrid, series hybrid, electronic continuously variable transmission (eCVT), generator, neutral, and the like).