The use of a carburetor with electronic mixture control allows you to maintain the optimal composition of the fuel-air mixture (with a stoichiometric ratio of 14.7:1) and optimal filling of cylinders in various engine operating modes, increase fuel efficiency and reduce the content of harmful impurities in exhaust gases, improve vehicle operating conditions, increase the reliability of the power supply system, and also facilitate maintenance and diagnostics. In the event of a failure of the electronic control system, the 2BE carburetor starts to work like a conventional carburetor. System «Ecotronic» performs the following functions.
Enrichment of the combustible mixture during start-up, warm-up and acceleration of the engine
During cold start, during warm-up and acceleration of the engine, enrichment of the combustible mixture is required. It is carried out depending on the speed of the crankshaft, the position of the throttle valve of the 1st chamber, the duration of the engine after a cold start, the temperature of the coolant and the opening speed of the throttle valve of the 1st chamber. Based on this information, the controller determines the required degree of enrichment of the combustible mixture and issues an appropriate control signal to the air damper servo. During acceleration, the air damper moves briefly in the closing direction. The moment of closing, its duration and the algorithm for re-opening the air damper are determined by the controller depending on the operating parameters.
Control of the amount of combustible mixture at start-up and at fast idle
The amount of combustible mixture required for a reliable start of the engine and its simultaneous transition to the fast idle mode is determined by the throttle valve servo of the 1st chamber, depending on the temperature of the coolant and the crankshaft speed. After the first excess of the preset idle mode, the filling of the cylinders is controlled by adjusting the idle speed of the engine.
Engine idle control
Idle speed is regulated independently of such parameters that usually affect it, such as the degree of engine burn-in (friction torque values), the temperature of the incoming air and atmospheric pressure, and is constantly maintained at a given level.
To this end, the measured crankshaft speed is continuously compared with a set value stored in the controller's memory. When the idle mode deviates from the nominal value, the position of the throttle valve of the 1st chamber is corrected by the servo drive in accordance with the proportional-integral control algorithm. The regulation control is chosen in such a way that the idling mode is regulated over the entire temperature range. This means that the nominal value of the idle speed is adjusted depending on the temperature of the coolant.
Fuel cut-off during engine speed reduction and engine shutdown
When closing the carburetor throttle, the fuel supply must be turned off.
To do this, the forced idle system (PXX) interrupts the fuel supply to the carburetor by completely closing the throttle valve of the 1st chamber at an engine speed above a certain value. The fuel supply to the carburetor is resumed as a result of the simultaneous action of the throttle valve servomotors of the 1st chamber and the air damper when the crankshaft speed is reduced to a certain threshold. This avoids interruptions in the operation of the engine when the process of combustion of the combustible mixture is resumed.