Variable Compression Ratio Engine Fuel Injection Control
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Solution Overview
Problem
Conventional internal combustion engines with fixed compression ratios cannot optimize fuel economy and engine power performance across varying operating conditions, leading to inefficiencies and increased particulate matter emissions in variable compression ratio (VCR) engines due to misaligned fuel injection timing with changing piston positions.
Innovation Solution
A method for adjusting fuel direct injection in VCR engines by varying the compression ratio and split injection ratio based on engine operating conditions, including actuating a variable compression ratio mechanism to optimize fuel delivery between intake and compression strokes, leveraging improved fuel evaporation and charge cooling effects at higher compression ratios to reduce abnormal combustion events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel injection timing is selected based on crankshaft position in a VCR engine, then injection timing can be scheduled for specific strokes, but the actual injection timing becomes misaligned with piston position when compression ratio changes, causing increased particulate matter emissions
Solution Approach 1:
The patent changes the control parameter from crankshaft position to piston position relative to the cylinder head. The controller adjusts injection timing based on the actual piston position, which varies with compression ratio, thereby maintaining proper injection timing alignment and reducing particulate matter emissions caused by fuel adhering to the piston
Solution Approach 2:
The system incorporates feedback from piston position sensing to dynamically adjust injection timing. The controller receives information about the actual piston position and modifies injection timing accordingly, creating a closed-loop control system that adapts to changing compression ratios
2Use of energy by moving object
If compression ratio is increased to improve thermal efficiency and fuel economy, then fuel evaporation improves and combustion stability increases, but the risk of abnormal combustion events increases
Solution Approach 1:
The patent utilizes parameter changes in fuel injection strategy based on compression ratio. At higher compression ratios, the controller adjusts injection timing and duration to leverage improved fuel evaporation while preventing abnormal combustion, optimizing both fuel economy and combustion reliability
Solution Approach 2:
The system dynamically adjusts fuel injection parameters based on operating conditions and compression ratio. The controller modifies injection timing, duration, and split injection ratios in real-time to maintain optimal combustion stability across varying compression ratios, preventing abnormal combustion events
3Device complexity
If fixed compression ratio is used in conventional engines, then engine structure is simple, but fuel economy and power performance cannot be optimized across different operating conditions
Solution Approach 1:
The patent implements a variable compression ratio system that dynamically adjusts the compression ratio based on operating conditions. The controller receives inputs about engine operation and actuates the VCR mechanism to provide optimal compression ratio, thereby optimizing fuel economy and power performance across different operating conditions
Solution Approach 2:
The system changes the compression ratio parameter dynamically based on operating conditions. The controller adjusts the compression ratio to match optimal values for different load and speed conditions, improving overall fuel economy while maintaining acceptable engine structure through controlled variability
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 enhances combustion stability, reduces emissions, and improves fuel economy by optimizing fuel injection timing and split ratios, extending engine component life and maintaining efficient operation across a range of conditions.
Implementation Method 1
fuel may evaporate more easily in the compression stroke, requiring less fuel mass to be delivered
Implementation Method 2
the different charge cooling effects realized from injecting fuel in the intake stroke relative to the compression stroke to reduce the propensity for abnormal combustion events
Data Source
AI summary
Methods and systems are provided for adjusting a fuel direct injection split ratio and injection timing in a variable compression ratio engine. In one example, as the compression ratio increases, the split ratio of fuel injected during an intake stroke relative to a compression stroke is increased, with a start of the intake stroke injection retarded and a start of the compression stroke injection advanced. Additionally, the fuel direct injection split ratio and injection timing may be further adjusted responsive to an indication of pre-ignition or knock.