Three-Planet-Row Hybrid Drive Layout for High-Speed E-CVT Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid driving systems in hybrid electric vehicles suffer from low transmission efficiency due to high energy losses in power conversion between mechanical and electrical forms, particularly in series connection modes and high-speed conditions.
Innovation Solution
A hybrid driving system incorporating a three-planet-row planet gear configuration with multiple operating elements (clutches and brakes) to realize various modes such as pure electric, E-CVT, engine direct drive/parallel, and braking energy recovery, optimizing power transmission efficiency through selective engagement of these elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If series connection mode is used, then optimal control of rotating speed/torque can be realized, but energy loss is relatively large due to two conversions of mechanical power to electrical power and back
Solution Approach 1:
The system dynamically switches between series connection mode and parallel connection mode based on operating conditions. The control unit determines whether to engage the first clutch C1 to connect the first motor M1 to the first planet gear Z2, transitioning from series mode (C1 disengaged) to parallel mode (C1 engaged), thereby optimizing the balance between control flexibility and energy efficiency
Solution Approach 2:
The hybrid driving system is segmented into distinct operational modes (series mode and parallel mode) that can be independently selected. The power transmission path is divided into separate routes: one through the electrical conversion path (series mode) and another through the mechanical direct connection path (parallel mode), allowing selective activation based on efficiency requirements
2Loss of energy
If parallel connection mode is used, then transmission efficiency is high, but the mechanical connection cannot guarantee the engine is always in a better working area
Solution Approach 1:
The system employs dynamic mode switching between parallel connection and series connection based on engine operating conditions. When the engine operates in its optimal working area, parallel mode is activated for high efficiency. When engine conditions require flexibility or optimal operating area cannot be maintained, the system transitions to series mode, thereby maintaining both high efficiency and adaptability
Solution Approach 2:
The control unit monitors engine operating parameters and dynamically adjusts the connection mode based on these parameters. By changing the operational state (engaging or disengaging clutch C1), the system adapts to varying engine working areas while maintaining optimal performance characteristics
3Adaptability or versatility
If parallel-series connection (power splitting type) is used, then both optimized control of engine and high-efficiency control of medium and high speeds are achieved, but the requirements for the ultimate power of motor are high during vehicle starting
Solution Approach 1:
The system segments the power delivery function between the first motor M1 and the second motor M2. The first motor M1, connected through the planetary gear mechanism, handles high-torque starting conditions with mechanical advantage. The second motor M2 provides additional power assistance when needed. This segmentation reduces the ultimate power requirement of each individual motor compared to a single motor system
Solution Approach 2:
The planetary gear mechanism acts as an intermediary between the first motor M1 and the output shaft, providing mechanical advantage during starting conditions. This intermediary mechanism amplifies the torque output of the first motor, thereby reducing the ultimate power requirement of the motor while maintaining the ability to provide optimized engine control
4Adaptability or versatility
If single E-CVT mode hybrid system is used, then pure electric mode and E-CVT hybrid mode can be realized, but transmission efficiency is low at high speeds due to two conversions of power
Solution Approach 1:
The system dynamically switches between E-CVT mode (first clutch C1 disengaged) and parallel mode (first clutch C1 engaged) based on speed conditions. At low to medium speeds, E-CVT mode provides flexible power distribution. At high speeds, the system transitions to parallel mode to eliminate the double power conversion losses, thereby maintaining both driving mode flexibility and high transmission efficiency across the full speed range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves higher transmission efficiency by enabling multiple working modes, reducing electric power loss, and allowing the engine to be started on demand, thereby improving vehicle performance and extending motor lifespan.
Implementation Method 1
the first sun gear is in external meshing transmission with the first planet gear, the first planet gear is in internal meshing transmission with the first gear ring
Implementation Method 2
a first motor and a second motor; the third sun gear is connected to the first motor, the first sun gear and the second gear ring are both connected to the second motor
Data Source
AI summary
A hybrid driving system and a hybrid electric vehicle. The hybrid driving system includes an engine, an input element (20), an output element (23), a box body (24), a first motor (13), a second motor (14), a first planet row, a second planet row, a third planet row, a first clutch (15) and a first brake (16). According to the hybrid driving system of the present disclosure, a basic three-planet-row planet gear configuration is provided through the planet row mechanical structure and the reasonable layout of multiple operating elements (the clutches and the brakes), which can realize at least two E-CVT working modes to obtain higher transmission efficiency.