In order to correspond to the exhaust emissions regulations that become severe every year, more advanced engine control becomes necessary. Engine engineers are concerned about the Hydrocarbons (HCs) that flow through the air-intake ports and that are difficult to precisely control. The main sources of the HCs are, the canister purge, PCV, back-flow gas through the intake valves, and Air / Fuel ratio (A/F) may be aggravated when they flow into the combustion chambers. The influences HCs give on the A/F may also grow even greater, which is due to the increasingly stringent EVAP emission regulations, by more effective ventilation in the crankcase, and also by the growth of the VVT-operated angle and timing, respectively.
In order to control the A/F more correctly, it is important to estimate the amount of HCs that are difficult to manage, and seek for suitable controls over fuel injection and so on. Therefore, the authors have developed a HC concentration measuring technology for the air-intake system using FID of which gas sampling performance has been remarkably improved. The characteristics of the system are as follows;
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Applicable to each point of the intake system
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Applicable to all engine operating conditions including the transition stage
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Small influences on the A/F control by gas sampling
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High accuracy; 1%F.S.
This report presents the results gained from the several tests carried out on EVAP purging, PCV gas supplying, and VVT system operation, as well as on the process of measuring technology development.