Engine idle control
The idle speed of the engine is controlled regardless of the degree of engine running-in (friction torque values), intake air temperature and atmospheric pressure and is constantly maintained at a given level. To do this, the controller constantly compares the measured engine speed with the nominal value entered into its memory. In case of deviation from the norm, the controller issues a signal to the servomotor to correct the position of the air damper.
In addition to the idle mode, the controller also takes into account the temperature of the coolant, which provides idle control when starting a cold engine at low ambient temperatures.
Enrichment of the combustible mixture during starting, warming up and increasing the engine speed
The controller determines the required degree of enrichment of the combustible mixture at start-up, during warm-up and increase in the engine speed depending on the crankshaft speed, throttle position of the 1st chamber, the duration of the engine operation after a cold start, the temperature of the coolant and the throttle opening speed 1 th camera. The corresponding controller output signal is applied to the carburetor during the movement of the air damper in the closing direction. In addition, the controller provides the ability to issue a command for a short movement of the air damper in the closing direction when the engine speed increases. The moment of closing, its duration and re-opening of the air damper are calculated by the controller depending on the operating parameters.
Control of the amount of combustible mixture at start-up and at fast idle
Depending on the coolant temperature and engine speed, the controller determines the amount of combustible mixture necessary for reliable engine start and its instantaneous and smooth transition to the fast idle mode, and issues a corresponding signal to the 1st chamber throttle servo. As soon as the idle speed is above the nominal value, the controller's idle control circuit takes over the control of filling the cylinders.
Fuel cut-off control at speed drop and at engine stop
When the engine speed drops, the forced idle system is activated: the fuel supply to the engine stops, but additional air still enters the cylinders. Stopping the fuel supply and increasing the filling of the cylinders during engine braking is carried out by closing the throttle valve of the 1st chamber when the crankshaft speed exceeds the threshold value equal to 1400 rpm. As soon as the engine braking speed drops to a threshold value, the controller output signals the resumption of fuel supply to the servomotors of the throttle valve of the 1st chamber and the air damper, thereby ensuring a relatively smooth (no failures) resumption of the combustion process of the combustible mixture. If the speed rises again during engine braking, the fuel supply and, consequently, the combustion of the combustible mixture is instantly resumed.
When the ignition is turned off, the throttle valve of the 1st chamber closes, the fuel supply stops and the engine immediately stops. After some time, the throttle valve of the 1st chamber returns to the start position in order to avoid jamming when it comes into contact with the diffuser surface.
Additional controller features
In addition to controlling the operation of the carburetor in the above modes, the controller performs the following tasks:
- Based on the operating parameters, it issues a fuel consumption signal to the economizer;
- controls the ignition timing at idle depending on the temperature of the intake manifold and the position of the idle switch.
When the idle switch is pressed (its contacts are open), and the temperature of the walls of the intake manifold exceeds 15°C, atmospheric pressure is supplied to the vacuum regulator of the ignition distributor via a solenoid valve and it does not affect the ignition timing.