Engine Restart Fuel Injection Sequencing for Rich Mixture Control
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Solution Overview
Problem
After automatic restart of an internal combustion engine, there is a risk of the air-fuel ratio shifting to a rich side due to high fuel pressure, affecting exhaust emission and fuel efficiency, especially when the requested torque is small.
Innovation Solution
An internal combustion engine system with an in-cylinder injection valve and a fuel pressure adjustment mechanism, controlled by a first and second controller, which executes compression stroke injection followed by intake stroke injection to adjust fuel pressure, ensuring the air-fuel ratio remains stoichiometric by limiting the number of intake stroke injections based on requested torque and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compression stroke injection is executed with high fuel pressure to promote fuel atomization and increase torque, then the internal combustion engine can restart quickly, but the air-fuel ratio shifts to a rich side after restart which affects exhaust emission and fuel efficiency
Solution Approach 1:
The patent applies periodic action by executing compression stroke injection a specific number of times (first number of times) followed by intake stroke injection a specific number of times (second number of times). This periodic injection pattern allows the fuel pressure to be controlled in cycles, ensuring quick restart while preventing excessive fuel accumulation that would cause rich air-fuel ratio and harmful emissions.
Solution Approach 2:
The patent changes the injection timing parameter from only compression stroke injection to a combination of compression stroke injection and intake stroke injection. By controlling the fuel pressure to a predetermined value during compression stroke and lowering it during intake stroke, the system maintains quick restart capability while preventing air-fuel ratio from shifting to rich side, thereby reducing harmful emissions.
2Productivity
If compression stroke injection is executed with high fuel pressure to promote fuel atomization and increase torque, then the internal combustion engine can restart quickly, but the actual fuel injection amount becomes larger than requested which affects fuel efficiency
Solution Approach 1:
The patent applies feedback by monitoring the fuel pressure and controlling the injection valve based on the relationship between injection timing and pressure. The system executes compression stroke injection to build up torque, then follows with intake stroke injection to reduce fuel pressure and correct the air-fuel ratio. This feedback control ensures the actual fuel injection amount matches the requested amount, preventing fuel waste and improving fuel efficiency while maintaining quick restart capability.
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 effectively suppresses the air-fuel ratio from shifting to the rich side, improving exhaust emission and fuel efficiency by precisely controlling fuel injection after automatic restart, particularly for smaller torque requests.
Implementation Method 1
The compression stroke injection is executed in a state in which a pressure of fuel is high to promote fuel atomization
Implementation Method 2
a pressure accumulation mechanism configured to accumulate the pressure of the fuel supplied to the in-cylinder injection valve
Data Source
AI summary
An internal combustion engine system includes an internal combustion engine including an in-cylinder injection valve and a fuel pressure adjustment mechanism, and a control device that executes fuel injection control at a time of automatic restart of the internal combustion engine that is automatically stopped, by controlling the in-cylinder injection valve and the fuel pressure adjustment mechanism, in which the control device includes a first controller that executes the compression stroke injection a first number of times after an automatic restart request is made and control the pressure of the fuel to a predetermined value, and a second controller that executes the intake stroke injection a second number of times after the compression stroke injection is executed the first number of times and make the pressure of the fuel lower than the predetermined value.