Engine Air-Fuel Ratio Stepped Control for Thermal Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control apparatuses for internal combustion engines face issues with thermal efficiency deterioration and response delay when changing combustion modes from stoichiometric to lean combustion, and vice versa, due to fluctuations in intake air and fuel injection.
Innovation Solution
A control apparatus that adjusts the air-fuel ratio in a stepped manner based on predetermined intake air amounts to maintain thermal efficiency and suppress torque fluctuations, using a torque suppression device like a motor-generator to manage engine torque during mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the intake air amount is increased to change over from stoichiometric combustion to lean combustion, then the combustion mode changes successfully, but the thermal efficiency deteriorates and response delay occurs
Solution Approach 1:
The control apparatus determines a preliminary changeover timing point before the actual combustion mode transition occurs. By predicting when the changeover should happen and preparing in advance, the system can execute the transition more efficiently without thermal efficiency deterioration or response delay. This preliminary timing determination allows the ECU to coordinate fuel injection and air-fuel ratio adjustments optimally.
Solution Approach 2:
The combustion mode changeover process is divided into distinct segments: a determination phase where changeover timing is identified, and an execution phase where the actual transition occurs. By segmenting the control process, the system can optimize each phase independently, ensuring that thermal efficiency is maintained while achieving timely mode transition.
2Object-generated harmful factors
If the air-fuel ratio is changed in a stepped manner to prevent intermediate ratios, then exhaust emission properties are improved, but the torque fluctuates and response delay increases
Solution Approach 1:
The system determines the optimal changeover timing in advance, allowing it to execute stepped air-fuel ratio changes without unnecessary delays. By knowing when the transition should occur, the ECU can coordinate the stepped changes efficiently, avoiding both intermediate air-fuel ratios and excessive response delay.
3Force
If the fuel injection amount is increased to ensure sufficient engine torque during acceleration, then the torque is maintained, but the air-fuel ratio becomes intermediate and exhaust emission deteriorates
Solution Approach 1:
By determining the changeover timing in advance, the system can coordinate fuel injection adjustments with the combustion mode transition. This ensures that torque requirements are met while avoiding intermediate air-fuel ratios that would deteriorate exhaust emissions.
Data Source
AI summary
A control apparatus for an internal combustion engine is provided. The control apparatus includes an ECU. The ECU is configured to change, in a stepped manner, an air-fuel ratio of the internal combustion engine so as to change over a combustion mode of the internal combustion engine between lean combustion and stoichiometric combustion, when an operating point of the internal combustion engine satisfies a first changeover condition that is defined by a rotational speed and a torque of the internal combustion engine. The first changeover condition is defined by the rotational speed and the torque that correspond to a predetermined intake air amount at which a thermal efficiency of the internal combustion engine is maintained before and after changeover of the combustion mode.