Lean-Burn Hybrid Engine Control via Load Threshold Switching
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Solution Overview
Problem
Lean-burning engines face challenges in maintaining stable combustion and efficiency at low loads and engine speeds, leading to potential engine misfire and reduced power output, limiting their use to only part of the engine map.
Innovation Solution
An engine control unit for a full hybrid engine that operates the internal combustion engine in lean-burn mode and switches to electric mode when the load level is below a defined threshold, using an electric motor to maintain battery charge and improve efficiency and emissions, with optional NOx concentration monitoring for adaptive threshold calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the internal combustion engine operates in lean-burn mode at low load levels, then fuel efficiency and emissions are improved, but combustion stability deteriorates and engine misfire occurs
Solution Approach 1:
The system dynamically adjusts the air-fuel ratio parameter based on operating conditions. At low load levels, the engine operates at stoichiometric ratio (lambda=1) to ensure stable combustion, while at higher load levels it transitions to lean-burn mode (lambda>1.3) to improve fuel efficiency and reduce emissions.
Solution Approach 2:
The engine control system continuously monitors load level and dynamically switches between operating modes (stoichiometric and lean-burn) based on real-time conditions. This dynamic adaptation allows the engine to maintain optimal performance and stability across the entire operating range.
2Object-generated harmful factors
If the internal combustion engine operates in lean-burn mode, then CO2 and hydrocarbon emissions are reduced, but power output decreases
Solution Approach 1:
The engine control system dynamically adjusts the air-fuel ratio based on load demands. During high power demand conditions, the system enriches the mixture to maintain adequate power output, while during low to medium load conditions it operates in lean-burn mode to minimize emissions.
Solution Approach 2:
The lambda parameter is adjusted according to operating conditions: operated at lambda=1 for power-critical situations and at lambda>1.3 for emissions-critical situations, optimizing the balance between power output and emissions reduction.
3Reliability
If the engine operates at stoichiometric point, then combustion stability is maintained, but fuel efficiency and emissions performance are limited
Solution Approach 1:
The engine control system dynamically switches between stoichiometric and lean-burn operating modes based on real-time load level detection. This allows the engine to exploit the fuel efficiency and emissions benefits of lean-burn operation whenever combustion stability permits, while maintaining stoichiometric operation only when necessary for stability.
Solution Approach 2:
The operating map is segmented into different regions: a stoichiometric region for low loads and high power demand, and a lean-burn region for medium to high loads where stability is maintained. This segmentation allows optimization for different operational priorities.
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
Enables the internal combustion engine to run in a clean and efficient lean-burn mode while the electric motor takes over in unstable regions, extending battery life and reducing emissions, allowing for broader lean-burn operation and improved power output.
Implementation Method 1
burn the fuel with an excess of air... Burning fuel in such an oxygen-rich environment is usually called lean-burning
Implementation Method 2
The full hybrid engine comprises an internal combustion engine and an electric motor
Data Source
AI summary
An engine control unit (400) for a full hybrid engine (100, 101) is provided. The full hybrid engine (100, 101) comprises an internal combustion engine (110) and an electric motor (120). The internal combustion engine (110) is coupled to the drivetrain via a clutch (130). The engine control unit (400) is configured to operate the internal combustion engine (110) in a lean-burn mode, to determine a current load level of the full hybrid engine (100, 101), and to compare the current load level to a lean-burn load threshold (210). The lean-burn load threshold (210) defines a load level below which stable operation of the internal combustion engine (110) in the lean-burn mode is impossible and/or undesirable. If the current load level of the full hybrid engine (100, 101) is below the lean-burn load threshold (210), the internal combustion engine (110) is decoupled from the drivetrain and the full hybrid engine (100, 101) is operated in an electric mode.