Engine Control Device Stabilizing Throttle via Reference Air-Fuel Ratio
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Solution Overview
Problem
In internal combustion engines with multiple cylinder groups, achieving precise control of air-fuel ratios and torque is challenging due to the sharing of a single throttle, leading to oscillatory throttle operation and instability in air quantity, which affects torque and air-fuel ratio precision.
Innovation Solution
A control device that sets a reference air-fuel ratio within the range of request air-fuel ratios for each cylinder group, using methods such as averaging or setting near the combustion limit ratio, to stabilize throttle operation and fuel injection, allowing for precise control of air quantities and torque realization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared throttle is used for multiple cylinder groups with different request air-fuel ratios, then device complexity is reduced, but air quantity stability deteriorates due to oscillatory throttle operation
Solution Approach 1:
The control device introduces a reference air-fuel ratio as a new parameter that is used to calculate target air quantity. By changing the calculation parameter from direct use of request air-fuel ratios to use of reference air-fuel ratio, the system stabilizes throttle operation while maintaining the ability to achieve different air-fuel ratios in different cylinder groups through fuel injection control.
2Measurement precision
If target air quantities are determined based on request air-fuel ratios for each cylinder group, then air-fuel ratio control precision is improved, but throttle operation stability deteriorates due to varying target throttle openings
Solution Approach 1:
The reference air-fuel ratio acts as an intermediary parameter between the request air-fuel ratios of different cylinder groups and the target air quantity calculation. This intermediary stabilizes the throttle control by providing a consistent basis for calculation, while the actual air-fuel ratio control is achieved through fuel injection amount adjustment rather than throttle variation.
3Adaptability or versatility
If oscillatory throttle operation is allowed to respond to changing request air-fuel ratios, then adaptability is improved, but combustion reliability deteriorates due to unstable air quantities
Solution Approach 1:
The control strategy substitutes mechanical throttle adjustment with electronic fuel injection control. Instead of using throttle oscillation to respond to changing air-fuel ratio requirements, the system uses electronic control of fuel injection amounts to achieve the desired air-fuel ratios, thereby maintaining combustion stability while preserving adaptability.
Data Source
AI summary
An internal combustion engine control device the present invention provides is a control device that can realize both of request torque and a request A/F for each of cylinder groups with high precision, even when the request A/F differs at each of the cylinder groups. The present control device sets a reference A/F within a range from the leanest A/F to the richest A/F out of the request A/Fs to the respective cylinder groups. The present control device calculates a target air quantity for realizing the request torque under the reference A/F, based on data that defines a relation between engine output torque and an air quantity in relation to an A/F. The present control device controls a throttle opening in accordance with the target air quantity, and controls fuel injection amounts of the respective cylinders in accordance with the request A/F s to the respective cylinder groups.