Engine Control Device Limiting Supercharging Pressure During Acceleration
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Solution Overview
Problem
In internal combustion engines with a turbocharger, the variable compression ratio mechanism struggles to prevent knocking and excessive cylinder inner pressure rises during acceleration, as the supercharging pressure can become too high before the mechanical compression ratio is sufficiently lowered, leading to issues like excessive fuel enrichment, reduced fuel economy, and combustion problems.
Innovation Solution
A control method and device that limit supercharging pressure based on the mechanical compression ratio, using a supercharger and an exhaust bypass valve to adjust supercharging pressure, ensuring the mechanical compression ratio is maintained within target limits during acceleration, thereby preventing excessive supercharging pressure and its associated issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the variable compression ratio mechanism is used to prevent knocking during acceleration, then knocking is reduced, but the supercharging pressure becomes too high before the mechanical compression ratio is sufficiently lowered, causing excessive cylinder inner pressure rise
Solution Approach 1:
The control device performs preliminary action by detecting the mechanical compression ratio and proactively limiting the supercharging pressure before excessive cylinder inner pressure rise occurs. The ECU restricts supercharging pressure based on the detected mechanical compression ratio during acceleration, preventing the timing mismatch between compression ratio change and supercharging pressure rise that would otherwise cause knocking and excessive pressure
Solution Approach 2:
The invention implements feedback control by continuously detecting the mechanical compression ratio and using this information to adjust the supercharging pressure limitation. The ECU receives feedback on the actual compression ratio state and dynamically modifies the supercharging pressure target value accordingly, creating a closed-loop control system that adapts to changing engine conditions
2Stress or pressure
If fuel increment is performed to suppress cylinder inner pressure rise, then excessive fuel enrichment occurs, reducing fuel economy and causing combustion problems
Solution Approach 1:
The control device performs preliminary action by limiting supercharging pressure based on mechanical compression ratio before excessive fuel enrichment is needed. By proactively restricting supercharging pressure during acceleration when the mechanical compression ratio has not yet been sufficiently lowered, the system prevents the need for large fuel increments, thereby avoiding excessive fuel enrichment and maintaining better fuel economy
Solution Approach 2:
The invention introduces supercharging pressure limitation as an intermediary control variable between mechanical compression ratio and cylinder inner pressure. Instead of directly controlling fuel injection to manage cylinder pressure, the system uses supercharging pressure as an intermediate parameter that indirectly influences cylinder pressure, thereby avoiding the need for excessive fuel enrichment
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
This approach suppresses delays in mechanical compression ratio changes and improves engine drivability by preventing excessive supercharging pressure, reducing fuel enrichment, and avoiding combustion failures, thus enhancing fuel economy and reducing emissions.
Implementation Method 1
a turbo charger supercharging intake air utilizing an exhaust energy
Implementation Method 2
an exhaust bypass valve which forms a bypass passage for exhaust gas from the exhaust turbine to the exhaust manifold
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
[Abstract] For example, during an acceleration transient period of time during which a demand load is raised, a supercharging pressure is raised before a mechanical compression ratio is lowered and an internal combustion engine falls in a high load state. At this time, there is a possibility that a generation of knocking and an excessive rise in a cylinder inner pressure occur. This possibility is a task to be solved. The internal combustion engine includes: a variable compression ratio mechanism which is capable of modifying the mechanical compression ratio; a turbo charger (2) which supercharges intake air utilizing an exhaust energy; and an exhaust bypass valve (7) which adjusts a supercharging pressure as a supercharging pressure adjustment mechanism. The mechanical compression ratio is detected by a control shaft sensor (34) and the supercharging pressure is limited on a basis of this mechanical compression ratio.