Supercharger Control Device for Backfire Suppression
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Solution Overview
Problem
Internal combustion engines with superchargers experience backfires due to increased temperature and pressure during supercharging, which existing water injection methods fail to adequately suppress.
Innovation Solution
A control device that determines the occurrence of backfires and adjusts the supercharging pressure by reducing it when backfires are detected, using a specific map to calculate the adjusted pressure based on the occurrence frequency, thereby minimizing the likelihood of backfires during supercharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is injected into the intake passage during supercharging, then the temperature of the intake passage decreases, but the backfire is not appropriately suppressed due to high pressure in the intake passage and cylinder
Solution Approach 1:
The control device changes the supercharging pressure parameter based on backfire occurrence history. When backfire occurs within a predetermined period, the supercharging pressure is reduced to a lower value, otherwise it is set to a higher value. This dynamic parameter adjustment resolves the contradiction by adapting the supercharging conditions to prevent backfire while maintaining efficiency when safe.
Solution Approach 2:
The control device uses feedback from backfire detection (via air-fuel ratio sensor or pressure sensor) to adjust supercharging pressure. The control unit determines whether backfire has occurred in a predetermined period and adjusts the supercharging pressure accordingly, creating a closed-loop control system that effectively suppresses backfire.
2Power
If supercharging pressure is increased to improve engine output, then the temperature and pressure in the cylinder increase, but backfire becomes more likely to occur
Solution Approach 1:
The supercharging pressure is made dynamic rather than fixed. The control device adjusts the supercharging pressure between a first (lower) value and a second (higher) value based on real-time backfire occurrence detection. This dynamic adjustment allows the system to maximize engine output when conditions are safe while preventing backfire when conditions are risky.
Solution Approach 2:
The control device takes preliminary anti-action by detecting backfire occurrence in advance and preemptively adjusting the supercharging pressure to prevent backfire. When backfire is detected within a predetermined period, the system reduces pressure before backfire can occur again, preventing the harmful effect rather than reacting to it.
3Loss of time
If supercharging is performed at high pressure to reduce engine load, then the likelihood of backfire increases due to higher temperature and pressure
Solution Approach 1:
The system dynamically adjusts supercharging pressure based on operational conditions and backfire history. By switching between high and low pressure modes, the system maintains fast response capability when safe while preventing backfire when necessary, resolving the contradiction between speed and reliability.
Data Source
AI summary
In an internal combustion engine having a cylinder in which an air-fuel mixture of gaseous fuel and intake air is combusted, an intake passage connected to the cylinder, and a supercharger for supercharging the intake air, in a case where backfire is generated in a set period before supercharging is performed by the supercharger, supercharging is performed at a smaller supercharging pressure than in a case where backfire is not generated in the set period.