HEV Transmission Structure with Planetary Gear and Mode Switching
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Solution Overview
Problem
Hybrid electric vehicles experience decreased efficiency during driving, leading to deteriorated fuel efficiency due to limitations in power split and parallel driving modes.
Innovation Solution
A transmission structure for hybrid electric vehicles incorporating an engine connected to either the front or rear wheel, a planetary gear part with a ring gear, sun gear, and carrier, a first motor generator, an overdrive brake, and a second motor generator, along with an output synchro and torque blocking mechanism, allowing for power split, parallel, and series driving modes to improve fuel efficiency and adapt to various driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power branch apparatus (planetary gear) is used to transfer engine power to output shaft, then mechanical power transfer efficiency is improved, but the system complexity increases and fuel efficiency deteriorates during certain driving conditions
Solution Approach 1:
The patent implements dynamic switching between power split mode and parallel driving mode based on driving conditions. The power branch apparatus can be selectively engaged or disengaged, allowing the system to adapt its power transfer mechanism dynamically. This resolves the contradiction by using the planetary gear for efficient mechanical power transfer when needed, while switching to alternative configurations when it causes energy loss.
Solution Approach 2:
The transmission system is designed to perform multiple functions: it can operate in power split mode for fuel-efficient cruising, switch to parallel driving mode for high-power demands, and disengage the power branch apparatus entirely when electrical power alone suffices. This multi-functionality allows the system to optimize fuel efficiency across diverse driving conditions while maintaining the capability for efficient mechanical power transfer when required.
2Adaptability or versatility
If hybrid vehicle systems are designed with multiple motor generators and power branch apparatus, then driving efficiency and adaptability are improved, but system size and complexity increase
Solution Approach 1:
The patent divides the hybrid powertrain into distinct functional modules: engine, first motor generator, second motor generator, power branch apparatus, and battery. Each component can be independently controlled and switched. This segmentation allows the system to achieve high adaptability by selectively engaging different modules while keeping the overall system complexity manageable through modular design and independent control of each segment.
3Loss of energy
If power split driving mode is used, then fuel efficiency is improved during steady-state operation, but the system cannot provide sufficient power during high-demand situations
Solution Approach 1:
The patent implements dynamic mode switching capability that transitions from power split driving mode to parallel driving mode when high power is required. The control system monitors driving conditions and seamlessly switches between operating modes, allowing the vehicle to maintain fuel efficiency during steady-state operation while providing sufficient power during high-demand situations by engaging both engine and motor generators in parallel.
Data Source
AI summary
A transmission structure of a hybrid electric vehicle (HEV) may include an engine connected to a front wheel of the hybrid vehicle, a planetary gear part connected to the engine, a first motor generator connected to the planetary gear part, an overdrive brake connected to the first motor generator, and a second motor generator connected to a rear wheel of the hybrid vehicle.