Constant-Ratio Hybrid Drivetrain Eliminates Transmission Complexity
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Solution Overview
Problem
Current hybrid electric vehicle drivetrains face inefficiencies due to low ICE to Generator efficiency, mechanical complications from transmissions, and the need for large battery packs in plug-in hybrids, limiting range and infrastructure reliance.
Innovation Solution
A constant-ratio independent series-parallel hybrid drivetrain for plug-in hybrid vehicles, utilizing a digital motor controller and constant gear ratio mechanisms to eliminate transmissions, optimize power transfer between electric motor/generator and internal combustion engine, and enable all-wheel-drive capabilities with reduced mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission is used for full-range use of ICE, then the vehicle can operate across a wide speed range, but mechanical complication increases and total efficiency decreases
Solution Approach 1:
The drivetrain is segmented into two independent power sources: an electric motor/generator for low-speed operation and an internal combustion engine for high-speed operation. Each power source operates independently within its optimal range, eliminating the need for a transmission to bridge speed ranges and reducing mechanical complexity.
Solution Approach 2:
A constant-ratio gearbox acts as an intermediary between the ICE and the differential, providing a fixed mechanical advantage that allows the ICE to operate at optimal speeds while delivering power to the wheels across a practical speed range without requiring a multi-speed transmission.
2Adaptability or versatility
If a transmission is used for full-range use of ICE, then the vehicle can operate across a wide speed range, but total efficiency decreases
Solution Approach 1:
The drivetrain is segmented into two independent power sources: an electric motor/generator for low-speed operation and an internal combustion engine for high-speed operation. Each power source operates independently within its optimal range, eliminating the need for a transmission to bridge speed ranges and reducing mechanical complexity.
Solution Approach 2:
The multi-speed transmission system is replaced with a constant-ratio gearbox and electronic control system. The digital motor controller manages power delivery and switching between power sources, replacing the complex mechanical shifting mechanisms with electronic control to minimize energy losses.
3Power
If a larger ICE is used to supplement the EMG, then power availability increases, but drivetrain efficiency decreases
Solution Approach 1:
The drivetrain is segmented into two independent power sources: an electric motor/generator for low-speed operation and an internal combustion engine for high-speed operation. Each power source operates independently within its optimal range, eliminating the need for a transmission to bridge speed ranges and reducing mechanical complexity.
Solution Approach 2:
Each power source is optimized for its specific operating range: the electric motor/generator is optimized for low-speed, high-torque applications while the ICE is optimized for high-speed operation. This local optimization ensures each component operates at peak efficiency in its designated range without requiring oversized components.
4Duration of action of moving object
If very large battery packs are used in plug-in electric drivetrain, then electric driving distance increases, but vehicle cost and weight increase
Solution Approach 1:
The drivetrain is segmented into two independent power sources: an electric motor/generator for low-speed operation and an internal combustion engine for high-speed operation. Each power source operates independently within its optimal range, eliminating the need for a transmission to bridge speed ranges and reducing mechanical complexity.
Solution Approach 2:
The battery pack serves multiple functions: providing power for electric-only driving, charging the electric motor during regenerative braking, and supporting the ICE during transition periods. This multi-functionality allows a smaller battery pack to achieve extended range without proportionally increasing weight.
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
This solution enhances drivetrain efficiency by minimizing power losses, extending vehicle range, and reducing mechanical complexity, while leveraging the strengths of both electric motor/generator and internal combustion engine power sources for improved fuel economy and reliability.
Implementation Method 1
the electric motor (EM) 10...allows the electric motor/generator (EMG) to convert electric energy to mechanical energy from zero RPM to a specified limit...The DMCI also allows the EMG to act as a generator which converts mechanical energy to electric energy
Data Source
AI summary
A drivetrain for a plug-in hybrid vehicle which uses constant gear ratios, rather than any type of multi-gear transmission (traditional transmission gears or CVT) to power the driven wheels in order to increase drivetrain efficiency. A transmission is not a necessary drivetrain component for vehicles with an electric motor/generator (EMG). The EMG is the only mechanical power source until highway speeds are achieved. At that time, the driver may choose to activate and engage the small internal combustion engine (ICE) and the EMG is usually electrically disconnected so that it does not regeneratively charge the vehicle batteries using the power created by the ICE. Constant gear ratios may be achieved by a mechanical gearing system or by a belt drive system. This drivetrain is only for plug-in hybrid vehicles where the batteries are primarily charged by AC electrical outlet or solar (photovoltaic) cells.