The main elements of the Aisan carburetor
1 - accelerator pump; 2 - retarding valve; 3 - mixture control valve (MICV); 4 - vacuum chamber; 5 - double-leaf suction interrupter; 6 - electromagnetic damper; 7 - piston amplifier; 8 - solenoid feedback valve; 9 - float chamber valve; 10 - solenoid valve free cut-off fuel; 11 - enrichment valve; 12 - idle adjustment screw (SAS 1); 13 - throttle potentiometer.
Elements included in the carburetor control system
1 - speed sensor; 2 - throttle position sensor; 3 - oxygen sensor; 4 - engine coolant temperature sensor; 5 - electromagnetic free closing valve; 6 - solenoid feedback valve; 7 - fuel filter; 8 - fuel pump; 8 - housing of the carburetor accelerator pump; 10 - solenoid feedback valve (FBSC); 11 - solenoid feedback valve (SCSV); 12 - electronic control unit (ECU).
Electronic control unit (ECU)
Based on information received from various sensors during operation, the ECU controls and controls the output and executive bodies that regulate the optimal air-fuel mixture. The ECU usually consists of an 8-bit microprocessor.
Coolant temperature sensor
This sensor is located in the intake manifold coolant passage. The sensor is a thermistor. The ECU detects the engine temperature via the sensor output voltage and uses it to optimize the richness of the mixture on a cold engine.
Throttle position sensor (TPS)
TPS is a variable resistor that rotates with the throttle shaft, determining the angle of rotation. When the damper shaft is rotated, the output voltage of the sensor changes, causing the ECU to control the opening of the damper by changing this voltage. Using this signal, the relay signal and other signals, the ECU maintains the optimum air-fuel ratio.
Engine speed sensor
Twice in one revolution of the crankshaft, there is a sudden increase in voltage at the negative pole of the ignition coil. By detecting these voltage changes and changing the time between peak voltages, the ECU calculates the engine speed, determines the way it works, and regulates the composition of the fuel-air mixture, as well as the ignition timing.
Oxygen sensor (Lambda probe)
The intake manifold oxygen sensor uses the principle of an oxygen concentration cell with a permanent electrolyte. This element is characterized by a change in output voltage at an air-fuel ratio close to stoichiometric.
Using this characteristic, the sensor determines the oxygen concentration in the exhaust gases and sends information about it to the ECU, which determines whether the air-fuel mixture is richer or leaner than the stoichiometric ratio and includes feedback to adjust the air-fuel mixture in the direction of the stoichiometric ratio. With this ratio, the three-way catalytic converter has an optimal exhaust gas cleaning capability.
Vacuum circuit breaker
This is a contact type switch actuated by vacuum in the intake manifold. When the damper closes, the vacuum pressure in the intake manifold, acting on the vacuum switch, closes its contacts. The ECU receives a signal that the throttle opening is close to opening for idling.
Feedback solenoid valve (FBSV)
The valve is installed in the cover of the float chamber of the carburetor. The ECU regulates the composition of the air-fuel mixture by changing the duty cycle of the FBS. The greater the degree of loading, the poorer the air-fuel mixture.
Free closing solenoid valve (SCSV)
This valve is located in the carburetor float chamber cap The ECU regulates the carburetor free flow system by changing the valve cycle.