08-16-2017, 10:16 PM
There is disclosed an electronic control system for controlling a carburetor equipped with a slow system system solenoid valve and an enrichment system solenoid valve of different control ranges whose openings are electromagnetically controlled to control the air-fuel ratio of a Mixture supplied to internal combustion engine. The control system calculates, based on signals representative of the engine operating condition including the engine temperature, the duty of control of the main system solenoid valve slow according to the air-fuel ratio required for various states Of the engine. When the value of this load exceeds a predetermined value, the solenoid valve of the enrichment system is added to the solenoid valve of the slow main system to accurately control the air-fuel ratio over a wide range.
The simple design and low cost of the carburetor make it an attractive proposal to be used for two-wheel applications in India and other countries. However, stringent emission standards pose a greater challenge in carburetor adaptation for different vehicle applications. The use of electronics to control the air-fuel ratio in a carburetor with closed control to comply with Euro-II standards is the driving force to carry out this project. The aim is to achieve the best efficiency of the catalytic converter when the air-fuel ratio is maintained in stoichiometry within a closed band. Variations inherent in the manufacture of carburetors may cause the air-fuel ratio to deviate from the stoichiometric and have an adverse effect on the catalytic converter production. The most efficient method of maintaining the air-fuel ratio within a near-near stoichiometric band is through closed-loop control. This method is widely used in passenger cars with fuel injection. However, the need for a low-cost system for two-wheeled vehicles is well known. A closed-loop electronic control system has been developed for the carburetor used in a 90cc four-stroke two-wheel vehicle to comply with Euro-II emission standards. This paper illustrates some of the research carried out to adapt electronic carburation with closed control Euro-II emission standards.