Engine Ignition Timing Control for Cycle-by-Cycle EGR Variation
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Solution Overview
Problem
Knocking occurrence timing changes due to varying air-fuel mixture temperature, especially in internal EGR systems, leading to suboptimal ignition timing and increased fuel consumption.
Innovation Solution
An internal combustion engine control device that measures gas temperature and EGR ratio during the compression stroke to correct ignition timing using a three-dimensional map, adjusting for cycle variations and optimizing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ignition timing is advanced to MBT (maximum brake torque) timing for optimal fuel consumption, then fuel consumption is optimized, but knocking occurs when air-fuel mixture temperature is high
Solution Approach 1:
The system performs preliminary detection of air-fuel mixture temperature and EGR ratio during the compression stroke, before ignition occurs. Based on these detected parameters, the ECU预先 determines the appropriate ignition timing correction value from a pre-stored map, ensuring that the ignition timing is optimized while preventing knocking before the combustion event takes place
Solution Approach 2:
The system detects actual air-fuel mixture temperature and EGR ratio during the compression stroke, compares these values with reference conditions, and adjusts ignition timing accordingly. This closed-loop feedback mechanism allows the system to adapt ignition timing to real-time combustion conditions, optimizing fuel consumption while preventing knocking
2Object-affected harmful factors
If ignition timing is retarded to prevent knocking in high-temperature conditions, then knocking is suppressed, but fuel consumption increases
Solution Approach 1:
The system determines the appropriate level of ignition timing retardation in advance, based on detected air-fuel mixture temperature and EGR ratio. By pre-calculating the optimal correction value from a stored map, the system minimizes unnecessary retardation, thereby suppressing knocking while maintaining fuel efficiency
Solution Approach 2:
The system dynamically changes ignition timing parameters based on detected air-fuel mixture temperature and EGR ratio. By adjusting ignition timing as a variable parameter according to actual combustion conditions, the system achieves optimal balance between knocking suppression and fuel consumption across different operating conditions
3Device complexity
If a fixed ignition timing map is used without considering air-fuel mixture temperature, then control is simple, but knocking occurs or fuel consumption increases due to cycle variations
Solution Approach 1:
The system transitions from a static, fixed ignition timing map to a dynamic control approach where ignition timing is adjusted in real-time based on detected air-fuel mixture temperature and EGR ratio. This dynamic adaptation allows the system to respond to cycle variations and changing combustion conditions, optimizing fuel consumption without significantly increasing control complexity
Solution Approach 2:
The system uses the engine's own combustion characteristics (detected through pressure sensors and calculated EGR ratio) to automatically adjust ignition timing. By leveraging the engine's inherent feedback mechanisms and pre-stored correction maps, the system achieves adaptive optimization without requiring complex external control systems
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 device ensures optimal ignition timing for each cycle, reducing fuel consumption by considering temperature and EGR ratio changes, thereby improving engine efficiency.
Implementation Method 1
pressure change inside a combustion chamber is detected during a compression stroke, an EGR gas concentration in the air-fuel mixture is calculated on the basis of the detected pressure change
Implementation Method 2
exhaust gas recirculation (EGR) is widely known, which causes an exhaust gas after combustion to be sucked into the cylinder again together with outside air and lowers combustion temperature of the air-fuel mixture to suppress the occurrence of knocking
Implementation Method 3
a mixture of fuel and air is formed in a cylinder and combusted by ignition or self ignition
Data Source
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AI summary
An object of the present invention is to predict change of a combustion limit due to cycle variation of temperature and an EGR ratio and perform correction every cycle to decrease an amount of combustion consumption. Therefore, in an internal combustion engine control device that controls an internal combustion engine including a cylinder and an exhaust pipe, the internal combustion engine control device includes a control unit configured to perform EGR control of controlling an exhaust gas in the exhaust pipe to return to an inner cylinder of the cylinder, obtain temperature of the gas in the internal cylinder and an EGR ratio in a state where both an intake valve and an exhaust valve are closed in an combustion cycle, and correct a combustion parameter in a same combustion cycle as the combustion cycle on the basis of the obtained gas temperature and the obtained EGR ratio.