Schematic diagram of the fuel injection system «KE-Jetromic»: 1 - fuel tank; 2 - fuel pump; 3 - fuel filter; 4 - fuel accumulator; 5 - fuel dispenser, 6 - air flow meter; 7 - throttle limit switch; 8 - additional air supply valve; 9 - electro-hydraulic control pressure regulator; 10 - fuel pressure regulator in the system; 11 nozzle, 12 - starting nozzle. 13 - coolant temperature sensor; 14 - electronic control unit
Operating principle
Fuel under pressure is constantly supplied to the injectors 11 (see diagram), installed in front of the intake valves. The nozzle sprays fuel, the amount of which is determined by its pressure and depending on the load (from underpressure in the inlet pipeline) and coolant temperature.
The regulation of the amount of fuel is provided by the dispenser-distributor 5, controlled by the air flow meter 6. and the electro-hydraulic control pressure regulator 9, controlled by the electronic unit 14 according to the signals of the coolant temperature sensor 13, the throttle limit switch 7 and the engine speed sensor, and also depending on engine speed.
The operation of the injection system in load and idle modes
The electric fuel pump 2 takes fuel from the tank and supplies it under pressure to the dispenser-distributor 5 through the accumulator 4 and the fuel filter 3.
Fuel enters the upper chambers of the dispenser-distributor under pressure, which is varied by the regulator 10 depending on the position of the distribution plunger. The amount of fuel supplied to the injectors is controlled by a diaphragm pressed against the outlets by control pressure. The control pressure regulator is an electrovalve controlled by an electronic unit. In load modes, the valve occupies the working position.
The auxiliary air supply valve is installed in the air duct, made parallel to the throttle valve, the opening of which is regulated by a conical screw. This valve maintains a minimum vacuum in the area of the air flow meter and provides additional air to the engine when the engine is idling. The idle speed of the engine is controlled automatically by an electromagnetic regulator controlled by an electronic unit.
The principle of operation of the dispenser-distributor of fuel: A - in the operating modes of the engine; B - at forced idle; B - when starting a cold engine and accelerating; 1 - housing of the dispenser-distributor; 2 - lever of the pressure disk of the air flow meter; 3 - upper chamber; 4 - lower chamber; 5 - fuel slip into the tank; 6 - fuel supply; 7 - tubes for supplying fuel to the nozzles; 8 - tube for supplying fuel to the starting injector; 9 - bimetallic spring
Starting a cold engine
The electric pump instantly creates pressure in the system. When the engine is started and for a certain time, depending on the temperature of the coolant, the starting injector 12 atomizes fuel under pressure in the intake piping, which ensures a cold engine start.
The auxiliary air supply valve 8 opens access to the intake pipeline for additional air, thereby providing an increase in the idle speed of the crankshaft. The enrichment of the mixture on a cold engine is carried out by the control pressure regulator, which reduces it by the amount necessary to increase the amount of fuel. After the engine warms up to operating temperature, the enrichment of the mixture stops.
Enrichment of the mixture in acceleration mode
When the throttle valve is opened, the mixture is enriched in a similar way by reducing the control pressure issued by the regulator 9 depending on the speed of the throttle valve.
Enrichment of the mixture at full load
At full engine load, the combustible mixture is enriched by commands from the electronic control unit based on information from the throttle limit switch.
Forced idle
When the throttle valve is closed, when the engine speed exceeds 1700 rpm, the control pressure regulator opens completely and a pressure equal to the fuel supply pressure is created in the lower chambers of the fuel dispenser-distributor. The flow of fuel to the injectors is changed.
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