Engine Bypass Control for Alcohol Fuel Startability
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Solution Overview
Problem
Internal combustion engines using mixed fuels of gasoline and alcohol face challenges in startability due to the decrease in volatility with higher alcohol mixing ratios, which affects warming-up performance.
Innovation Solution
A control device with a mixing ratio determining means, bypass quantity varying means, and bypass control means that adjusts the bypass quantity before and after first explosion based on alcohol mixing ratio and engine temperature to enrich the air-fuel ratio, ensuring excellent first explosion and improved startability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mixing ratio of alcohol in the mixed fuel is increased, then the warming-up performance of the internal combustion engine deteriorates, but the startability of the engine is also deteriorated due to decreased volatility
Solution Approach 1:
The control device performs preliminary enrichment of the air-fuel ratio before the first explosion by controlling the bypass quantity based on the detected alcohol mixing ratio. This preliminary action ensures that sufficient volatile fuel is available for successful ignition and first explosion, even when the overall fuel mixture has low volatility due to high alcohol content. After the first explosion, the control device then implements the warming-up control strategy appropriate for high alcohol mixing ratios.
2Ease of operation
If the bypass quantity before first explosion is reduced to enrich the air-fuel ratio for high alcohol mixing ratios, then the startability is improved, but the bypass quantity needs to be increased after first explosion for warming-up performance
Solution Approach 1:
The control device dynamically adjusts the bypass quantity based on the engine operating phase and detected alcohol mixing ratio. Before the first explosion, the bypass quantity is reduced to enrich the air-fuel ratio for reliable starting. After the first explosion, the bypass quantity is increased to provide the necessary airflow for warming-up performance. This dynamic adjustment allows the system to optimize both startability and warming-up performance according to the specific operational requirements at different phases.
Solution Approach 2:
The control device detects the alcohol mixing ratio in advance and uses this information to pre-adjust the bypass quantity before the first explosion occurs. This preliminary adjustment ensures the air-fuel ratio is properly enriched for starting conditions. After the first explosion, the control device then transitions to the appropriate warming-up control strategy, effectively preparing the system in advance for different operational phases.
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
An intake passage (26) of an engine has a main flow channel (26A) provided with a throttle valve (32) and a bypass flow channel (26B) for bypassing the throttle valve (32). A bypass quantity adjusting mechanism (33) is provided in the bypass flow channel (26B) for adjusting a bypass quantity. A control device (40) for an engine includes a mixing ratio determining part (43) for detecting or estimating a mixing ratio of alcohol of a fuel and a storing part (42) for storing the determined mixing ratio of ethanol. The control device (40) controls the bypass quantity adjusting mechanism (33) so that a bypass quantity before first explosion would be smaller than a bypass quantity after first explosion in the case that the mixing ratio of ethanol, the mixing ratio being stored in the storing part (42), is equal to or more than a predetermined value.