Engine Control Device for Partial Compression-Ignition Combustion
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Solution Overview
Problem
Partial compression-ignition combustion engines experience discomfort due to frequent mode switching, leading to repeated noise changes, as they switch between different combustion modes based on factors like combustion noise, which affects the comfort of occupants in the cabin.
Innovation Solution
A control device for a compression-ignition engine that sets a target combustion center of gravity for both modes and uses a noise index value to switch between modes only when necessary, ensuring a given time period elapses before resuming the first mode, thereby reducing frequent mode switching and associated noise changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mode switching is allowed without restriction to control combustion noise, then combustion noise can be reduced, but mode switching occurs frequently causing discomfort to occupants
Solution Approach 1:
The control device determines target values for control amounts in advance for both combustion modes, ensuring that combustion center of gravity positions are optimized before switching occurs. This preliminary setup allows for smoother transitions and reduces the frequency of switching by having pre-calculated optimal parameters ready.
Solution Approach 2:
The system implements a cooling period where a second mode cannot be selected for a predetermined time after switching from the first mode to the second mode. This periodic restriction prevents frequent oscillating switches between modes, reducing noise fluctuations that cause occupant discomfort while still allowing noise control when necessary.
2Object-affected harmful factors
If combustion mode is switched frequently to control noise, then noise levels can be managed, but fuel efficiency deteriorates due to repeated switching
Solution Approach 1:
By implementing a cooling period that prevents re-selection of the second mode for a predetermined time after switching, the system reduces the number of mode transitions. This periodic restriction minimizes energy loss associated with frequent switching while maintaining the ability to control combustion noise when truly necessary.
Solution Approach 2:
The control device continuously monitors combustion noise levels and uses this feedback to determine when mode switching is actually necessary. By base(ing) switching decisions on real-time noise measurements rather than arbitrary thresholds, the system avoids unnecessary mode changes that would waste fuel, while still responding effectively to actual noise problems.
3Object-affected harmful factors
If EGR ratio is increased to reduce combustion noise, then noise levels decrease, but combustion efficiency is reduced
Solution Approach 1:
The system dynamically adjusts the EGR ratio based on real-time combustion noise levels rather than using a fixed high EGR ratio. By making the EGR ratio variable and responsive to actual noise conditions, the system maintains low noise levels when needed while preserving combustion efficiency during normal operation, avoiding the continuous efficiency penalty of a permanently high EGR setting.
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 configuration minimizes discomfort by reducing frequent noise changes and maintaining low combustion noise levels, while ensuring smooth mode switching and improved fuel efficiency by maintaining the low EGR ratio mode unless noise exceeds a threshold.
Implementation Method 1
combust a portion of the mixture gas by spark-ignition using a spark plug
Implementation Method 2
the remaining mixture gas is combusted by self-ignition (CI (Compression Ignition) combustion)
Data Source
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AI summary
A control device for a compression-ignition engine in which partial compression-ignition combustion including spark ignition combustion performed by combusting a portion of mixture gas inside a cylinder by spark ignition followed by CI combustion performed by causing the rest of the mixture gas inside the cylinder to self-ignite is executed within a part of an engine operating range, is provided, including a manipulator configured to change an EGR ratio and/or an air-fuel ratio, and a controller configured to control the manipulator during the partial compression-ignition combustion to switch a combustion mode between first and second modes in which the EGR ratio is higher than the first mode and/or the air-fuel ratio is lower than the first mode. After the first mode is switched to the second mode, if a condition is satisfied, the controller causes the resumption to the first mode after a given period of time has elapsed from the switching.