Engine Controller Combustion Mode Switching via TIVC Estimation
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Solution Overview
Problem
Existing engine systems face challenges in seamlessly switching between compression ignition (CI) and spark ignition (SI) combustion modes based on engine load, leading to difficulties in maintaining optimal combustion stability and fuel efficiency due to the temperature of the mixture gas inside the cylinder.
Innovation Solution
An engine system with a controller that adjusts the combustion mode by estimating the in-cylinder temperature at the intake valve closing timing, using a combination of compression ignition and flame propagation to ensure stable combustion, and varying the injection timing and amount of fuel to optimize combustion based on engine load and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the combustion mode is switched between CI and SI combustion corresponding to engine load change, then fuel efficiency can be improved, but it is difficult to instantly change the T IVC inside the cylinder to match the target combustion mode
Solution Approach 1:
The system performs preliminary estimation of the intake-valve-closing temperature (T IVC) based on engine operating conditions (intake air temperature, engine speed, load, EGR rate) before combustion occurs. This allows the controller to predict the thermal state of the cylinder and proactively select the appropriate combustion mode (CI or SI) in advance, ensuring rapid response to load changes without waiting for actual temperature measurements.
Solution Approach 2:
The system uses feedback from multiple sensors (intake air temperature sensor, engine speed sensor, load sensor, EGR rate sensor) to continuously monitor engine operating conditions. The controller compares the estimated T IVC with predetermined thresholds and adjusts the combustion mode accordingly, creating a closed-loop control system that maintains optimal combustion stability while responding quickly to load changes.
2Use of energy by moving object
If the T IVC is not satisfied even when the engine load is appropriate for CI combustion, then CI combustion cannot be appropriately performed, making it impossible to improve both fuel efficiency and combustion stability
Solution Approach 1:
The system introduces an intermediary estimation model that calculates the intake-valve-closing temperature (T IVC) based on intermediate parameters (intake air temperature, engine speed, load, EGR rate) before combustion occurs. This intermediary calculation allows the controller to determine whether CI combustion conditions are met and switch to SI combustion as a mediator when T IVC is insufficient, preventing combustion instability while maintaining fuel efficiency through intelligent mode selection.
3Use of energy by moving object
If the entire mixture gas combusts by compression ignition when T IVC is above the first temperature, then fuel efficiency is improved, but when T IVC is below the first temperature, abnormal combustion occurs reducing combustion stability
Solution Approach 1:
The system changes the combustion mode parameter based on the T IVC parameter. When the estimated T IVC exceeds a first predetermined temperature, the controller selects CI combustion for improved fuel efficiency. When T IVC is below the threshold, the controller switches to SI combustion to maintain combustion stability and prevent abnormal combustion. This dynamic parameter adjustment resolves the contradiction between fuel efficiency and combustion stability.
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 improves both fuel efficiency and combustion stability by allowing the engine to switch between CI and SI modes effectively, reducing abnormal combustion and enhancing thermal efficiency.
Implementation Method 1
an injector attached to the engine and configured to inject fuel into the cylinder
Implementation Method 2
a spark plug attached to the engine and configured to ignite a mixture gas of fuel and intake air
Implementation Method 3
the mixture gas inside the cylinder combusts by compression ignition
Implementation Method 4
at least part of the mixture gas inside the cylinder combusts by flame propagation
Implementation Method 5
a variable valve operating device connected to an intake valve and an exhaust valve, and configured to control opening and closing of the intake valve and the exhaust valve to adjust a filling amount of the intake air
Data Source
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AI summary
An engine system is provided, including a controller which estimates an intake-valve-closing temperature inside a cylinder. When an engine operates at a given speed and a demanded engine load is a first load or a second load (> the first load), the controller controls so that a mixture gas inside the cylinder combusts by compression ignition, and controls so that, at the first load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a first temperature, and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the first temperature, whereas at the second load, the entire mixture gas combusts by compression ignition when the intake-valve-closing temperature is above a second temperature (< the first temperature), and at least part of the mixture gas combusts by flame propagation when the intake-valve-closing temperature is below the second temperature.