Dual-Piston Genset Cycle for Efficient Vehicle Electrification
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Solution Overview
Problem
Current battery electric vehicles face range anxiety due to extreme temperature effects on battery performance and low energy density, while conventional internal combustion engines for range extenders have low power efficiency and high emissions, and the lack of charging infrastructure poses challenges for commercial vehicle electrification.
Innovation Solution
The dedicated hybrid cycle (DHC) with dual pistons in internal combustion engines, where the Otto and Atkinson pistons have independent movements and different top dead centers, enhances brake thermal efficiency and eliminates the need for external exhaust gas recirculation, enabling more efficient fuel-to-electricity conversion using SI or CI combustion, and can be used in gensets for mobile charging of BEVs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional four-stroke engines are used for range extenders, then the engine design is simpler, but the power efficiency is low due to one power stroke per two revolutions
Solution Approach 1:
The piston is segmented into two independent pieces: the Otto piston piece connected to the crankshaft and the Atkinson piston piece with independent movement. This segmentation allows each piston to perform different functions - the Otto piston provides one power stroke per revolution while the Atkinson piston enables longer expansion strokes, achieving higher power efficiency without compromising structural integrity
Solution Approach 2:
The Atkinson piston piece is designed with independent dynamic movement from the Otto piston piece, allowing different stroke lengths and timing. The Atkinson piston can have a longer power stroke than compression stroke, optimizing expansion while the Otto piston maintains synchronous operation with the crankshaft, thereby improving overall power efficiency
2Use of energy by moving object
If external EGR mechanism is added to improve combustion efficiency, then the combustion efficiency improves, but the device complexity increases
Solution Approach 1:
The dual piston system enables self-service exhaust gas recirculation through its inherent operational characteristics. The Atkinson piston's longer expansion stroke and independent timing create natural pressure differentials that facilitate exhaust gas recirculation without requiring external EGR mechanisms, thereby maintaining combustion efficiency while avoiding additional complexity
Solution Approach 2:
The functions of exhaust gas recirculation and power generation are merged into the dual piston system itself. The Atkinson piston piece not only generates power through its longer expansion stroke but also inherently manages exhaust gas flow and recirculation, combining multiple functions that would traditionally require separate systems
3Power
If two-stroke engines are used to increase power output, then the power efficiency improves, but the emissions increase and durability decreases
Solution Approach 1:
The patent applies different quality characteristics to different piston pieces: the Otto piston piece operates with traditional four-stroke characteristics for controlled emissions, while the Atkinson piston piece provides extended expansion for improved efficiency. This local differentiation allows high power output similar to two-stroke engines while maintaining the emission control and durability benefits of four-stroke operation
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 approach significantly boosts the efficiency of internal combustion engines, reduces emissions, and provides a practical solution for electrifying hard-to-abate vehicles by optimizing fuel-to-electricity conversion and minimizing carbon dioxide emissions, while offering a mobile charging solution for BEVs.
Implementation Method 1
The top dead centers for both Otto and Atkinson piston can be different so that the burnt gas retention can be used to replace external EGR mechanism
Implementation Method 2
SI and CI can be applied principally for combustion ignition as designed
Data Source
AI summary
This invention presents an innovative technology, dedicated hybrid cycle, for dual piston based engines, which can be further developed as mobile chargers for electric vehicles. This design re-defines the single engine piston/crankshaft configuration in conventional internal combustion engines as two sets per the combustion process: Otto piston and Atkinson piston; correspondingly, there are Otto crankshaft and Atkinson crankshaft. As a matter of fact, the Atkinson crankshaft can be realized through a cam as well. The Atkinson mechanism is dedicated to accomplish high combustion efficiency, while the Otto crankshaft for engine output only. Periodically, the hybrid combination of both Atkinson and Otto cycle can significantly improve the engine efficiency and torque density. This innovative combustion mechanism is further developed for genset applications to generate electricity on the vehicles in a most efficient manner.