Engine Control Device Combustion State Detection
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Solution Overview
Problem
Existing control systems for internal combustion engines face challenges in detecting combustion states without using in-cylinder sensors, leading to increased costs and complexity, particularly in estimating combustion pressure and correcting EGR rates and air-fuel ratios accurately.
Innovation Solution
A control device that utilizes a processor to operate the first combustion timing or period from a crank angle sensor, calculates heat generation rates, in-cylinder pressure, and unburned gas temperature, and learns the correspondence between combustion speed and timing or period to detect combustion states without in-cylinder sensors, thereby reducing manufacturing costs and improving control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an in-cylinder pressure sensor is used to directly measure combustion pressure for detecting combustion state, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses crank angle sensor data as an intermediary to indirectly infer combustion pressure characteristics. Instead of directly measuring pressure with a sensor, the system calculates combustion timing and duration from crank angle information, which serves as a mediator between the sensor data and combustion state determination.
Solution Approach 2:
The patent replaces the mechanical/physical pressure sensing system with a computational approach. By substituting the direct pressure measurement mechanism with calculations based on crank angle data and heat generation rate models, the system achieves combustion state detection without requiring expensive in-cylinder pressure sensors.
2Measurement precision
If a crank angle sensor with high accuracy is used to estimate combustion pressure through dynamic relationship calculation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the necessary information from the crank angle sensor data - specifically combustion timing and duration - rather than attempting to calculate full combustion pressure. This extraction approach simplifies the system by removing the need for complex dynamic relationship calculations and high-accuracy sensor requirements.
Solution Approach 2:
The patent uses standard, low-cost crank angle sensors instead of expensive high-accuracy sensors. The system accepts that the sensor data will be processed through simplified calculations rather than requiring the sensor itself to be highly accurate, thereby using cheaper components that fulfill the functional requirement.
3Loss of energy
If exhaust gas recirculation rate is increased to reduce pump loss and knocking, then energy efficiency is improved, but combustion stability deteriorates
Solution Approach 1:
The patent implements feedback control by continuously monitoring combustion timing and duration from crank angle data and adjusting the EGR rate accordingly. When combustion becomes unstable (indicated by abnormal timing or duration), the system reduces EGR rate to restore stability, creating a closed-loop control system that balances energy efficiency and combustion reliability.
Solution Approach 2:
The patent dynamically adjusts the EGR rate based on real-time combustion conditions rather than using a fixed rate. The system modifies the EGR amount in response to changing combustion characteristics, allowing optimal EGR rates that adapt to varying engine conditions and maintain both efficiency and stability.
Data Source
AI summary
A processor (B705, B706) of a control device for an internal combustion engine 1 operates a first combustion timing (MFB 50) or a first combustion period (IG 100_1) in a cylinder of the internal combustion engine 1 from a crank angle detected by a crank angle sensor 20. A processor (B702) operates a heat generation rate based on a first combustion timing or a first combustion period. A processor (B703) operates in-cylinder pressure and in-cylinder unburned gas temperature based on the heat generation rate. A processor (B704) operates a first combustion speed (laminar flow combustion speed SL1) based on the in-cylinder pressure and the in-cylinder unburned gas temperature. A processor (B707) learns a correspondence relationship between the first combustion speed and the first combustion timing or the first combustion period.