Engine Compression Ratio Control for Sensor Failure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Internal combustion engines with mechanical compression ratio control systems face challenges in preventing pre-ignition and knocking when a detection sensor abnormality occurs, as reducing intake air or delaying ignition timing becomes insufficient at higher compression ratios.
Innovation Solution
A control system that lowers the mechanical compression ratio to its minimum value when an abnormality is detected in the detection device, thereby reducing combustion end temperature and preventing pre-ignition and knocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the mechanical compression ratio is raised to maximum when a detection abnormality occurs, then the engine can maintain high power output, but pre-ignition or knocking will occur due to excessive combustion end temperature
Solution Approach 1:
The control device applies preliminary anti-action by detecting abnormalities in the detection device and proactively lowering the mechanical compression ratio to a predetermined value before pre-ignition or knocking can occur. This preventive measure eliminates the harmful effects by adjusting the compression ratio in advance rather than reacting after the problem manifests.
Solution Approach 2:
The patent employs a simple control strategy that sacrifices optimal power output (using a lower, predetermined compression ratio) rather than implementing complex real-time monitoring and adjustment systems. This approach accepts reduced performance as a trade-off for reliably preventing pre-ignition and knocking when detection abnormalities occur.
2Object-affected harmful factors
If reducing intake air amount and delaying ignition timing are used to suppress knocking, then knocking can be suppressed at moderate compression ratios, but these measures become insufficient when the maximum mechanical compression ratio is further increased
Solution Approach 1:
The patent applies parameter changes by fundamentally altering the compression ratio parameter to a predetermined lower value when detection abnormalities are detected. This goes beyond minor adjustments like reducing intake air or delaying ignition timing, and instead changes the fundamental compression ratio parameter to ensure knocking suppression effectiveness across all compression ratio levels.
3Use of energy by moving object
If the mechanical compression ratio control system sets the compression ratio to maximum upon detection abnormality, then the system maintains high compression for efficiency, but the reliability of preventing pre-ignition and knocking deteriorates
Solution Approach 1:
The control device implements beforehand cushioning by preparing a safe predetermined compression ratio value in advance that is known to prevent pre-ignition and knocking. When detection abnormalities occur, the system immediately switches to this pre-prepared safe state, cushioning against the potential harmful effects before they can manifest.
Data Source
AI summary
An internal combustion engine wherein a variable compression ratio mechanism which can change the mechanical compression ratio and a detection sensor for detecting the mechanical compression ratio are provided and wherein the mechanical compression ratio is controlled based on the mechanical compression ratio detected by the detection sensor. When a signal line of the detection sensor breaks, the mechanical compression ratio is lowered to the minimum mechanical compression ratio.