Method and device for controlling excess air ratio of gasoline engine catalytic converter

Abstract

The invention relates to the technical field of engine pollutant emission control, and provides a method and device for controlling an excess air ratio of a catalytic converter of a gasoline engine. The method for controlling the excess air ratio of the catalytic converter of the gasoline engine according to the present invention includes: after the engine is started and before the catalytic converter is ignited, at the engine idling stage, controlling the excess air ratio at both the first set value and the second set value switch alternately until the excess air ratio sensor realizes a closed loop; wherein, the excess air ratio is the ratio of the amount of air actually supplied for fuel combustion to the standard air amount, when the excess air ratio is controlled at the first setting When the air-fuel ratio is greater than 14.7, lean control is performed; when the excess air ratio is controlled at the second set value, the air-fuel ratio is less than 14.7, and rich control is performed. Through the above-mentioned technical scheme, it can be realized to reduce NMOG and NO at the same time at low cost X emissions.

Description

technical field [0001] The invention relates to the technical field of engine pollutant emission control, in particular to a method and device for controlling an excess air ratio of a gasoline engine catalytic converter. Background technique [0002] With the gradual implementation of exhaust emission regulations such as China VI a / b, Euro VI a / b, and North American LEVIII. In particular, NMOG (non-methane organic gas) + NO is stipulated in SULEV20 of the LEVIII regulation X (nitrogen oxides such as NO and NO 2 ) emission limit is as low as 20mg / mile, so special attention should be paid to the exhaust emission characteristics after the first start of the engine, because the exhaust emissions produced in the first stage of the FTP-75 driving test cycle are higher than the weighted average tailpipe exhaust emissions More than half the amount. Due to the addition of NMOG+NO to the limits X Therefore, the average light-off temperature of the catalytic converter, which functi...

AI Technical Summary

Problems solved by technology

The excess air ratio at startup is determined by the fuel injection amount calculated based on the intake air volume, but there is an error between the intake air amount and the injection amount itself, so it is difficult to achieve precise control of the excess air ratio λ=1

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