Engine Intake Valve Timing Control for SPCCI Noise Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The implementation of Homogeneous-Charge Compression Ignition (HCCI) combustion in engines faces challenges such as varying combustion start timing due to external factors and difficulty in controlling engine load during transient operations, leading to excessive combustion noise and instability in SPCCI combustion.
Innovation Solution
A control system for an engine that adjusts the open timing of the intake valve based on engine load, creating a lean air-fuel ratio environment and controlling the spark plug to achieve partial compression-ignition combustion, reducing combustion noise while maintaining suitable flame propagation by advancing the intake valve timing at low loads and retarding it at high loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the open timing of the intake valve is advanced to increase residual gas amount for improving SI combustion stability at low engine load, then the combustion noise increases excessively at high engine load
Solution Approach 1:
The patent applies dynamics by making the intake valve timing adjustable rather than fixed. The control system dynamically changes the open timing of the intake valve based on engine operating conditions (load and speed). At low engine load, the intake valve timing is advanced to increase residual gas amount and improve SI combustion stability. At high engine load, the timing is retarded to reduce combustion noise, thus adapting the system to different operational requirements.
Solution Approach 2:
The patent changes the timing parameter of the intake valve based on engine operating conditions. By adjusting the open timing parameter dynamically according to engine load and speed, the system optimizes the balance between combustion stability and noise reduction across different operating ranges.
2Object-affected harmful factors
If the open timing of the intake valve is retarded to reduce residual gas amount for reducing combustion noise at high engine load, then the stability of SI combustion deteriorates at low engine load
Solution Approach 1:
The system dynamically adjusts intake valve timing based on real-time engine operating conditions. The control unit monitors engine load and speed, then automatically retards the intake valve timing at high load to reduce noise while advancing it at low load to maintain combustion stability, eliminating the need for manual intervention.
Solution Approach 2:
The timing parameter of the intake valve is changed dynamically based on engine operating conditions. The control system modifies this parameter to optimize performance across different load ranges, retarding timing at high load to reduce noise and advancing it at low load to maintain stability.
3Loss of energy
If HCCI combustion is implemented to improve thermal efficiency, then the combustion start timing varies greatly due to external factors and control during transient operation becomes difficult
Solution Approach 1:
The patent introduces spark-ignition combustion as an intermediary mechanism to control and stabilize the combustion process. The spark plug initiates combustion at a precise timing, serving as a mediator between the pilot injection and main fuel injection, thereby enabling better control over combustion start timing and improving transient operation control while maintaining thermal efficiency benefits.
Solution Approach 2:
The combustion process is segmented into distinct phases: pilot fuel injection to initiate combustion, spark-ignition combustion to control the start timing, and main fuel injection for sustained combustion. This segmentation allows independent optimization of each phase, improving overall control during transient operations while maintaining thermal efficiency.
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
The solution effectively reduces combustion noise and improves the stability of SI combustion in SPCCI mode by optimizing the in-cylinder temperature and pressure conditions, enhancing fuel efficiency and thermal performance.
Implementation Method 1
a spark plug configured to ignite a mixture gas containing the fuel injected by the injector and air
Implementation Method 2
combust a portion of the mixture gas by spark-ignition... after forcibly combusting a portion of the mixture gas through flame propagation caused by spark-ignition
Implementation Method 3
The in-cylinder temperature increases as pressure inside the cylinder (in-cylinder pressure) increases. An increase of the in-cylinder pressure on the compression stroke
Implementation Method 4
the remaining mixture gas is combusted by self-ignition (CI combustion)... the remaining mixture gas combusts at a plurality of positions simultaneously without flame propagation
Implementation Method 5
an intake valve configured to open and close the intake port... a control system includes an intake variable mechanism configured to change an open timing of the intake valve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A compression-ignition engine control system is provided, which includes an intake variable mechanism and a controller. Within a first operating range and a second operating range on a higher engine load side, the controller controls the variable mechanism to form a gas-fuel ratio (G/F) lean environment in which an air-fuel ratio inside a cylinder is near a stoichiometric air-fuel ratio and burnt gas remains inside the cylinder, and controls a spark plug to spark-ignite mixture gas inside the cylinder to combust in a partial compression-ignition combustion. The controller controls the variable mechanism to advance the intake valve open timing on an advancing side of a TDC of the exhaust stroke, as the engine load increases within the first range, and retard the intake valve open timing on the advancing side of the TDC of the exhaust stroke, as the engine load increases within the second range.