6. Fuel systemFuel system
|1 – fuel return pipeline;
2 – fuel supply pipeline;
3 – fuel filter (high pressure);
4 – fuel nozzle;
5 – pressure regulator;
|6 – fuel supply block;
7 – a quencher of pulsations (only on the TED engine);
8 – fuel tank;
9 – cover of a toplivonalivny mouth;
10 – toplivonalivny mouth;
11 – the pipeline (to nozzles)
On the majority of fuel systems of more than 90% of fuel comes back to the fuel tank in the normal operational mode.
Temperature of the fuel returned in the fuel tank increases by 7–15 °C because it heats up passing under the bottom of the car and about the hot engine, and also due to internal friction and friction about walls of pipelines.
Continuously returned warmed-up fuel increases fuel temperature in a tank.
In too time, the fuel compressed up to the pressure of 320-350 kPa in the fuel highway, passing through pressure regulator, comes to the fuel tank under small pressure.
In this case fuel evaporation, in relation to the elements having lower evaporation increases, and vapors of fuel come to the fuel tank.
Fuel vapors from the fuel tank do not get to the atmosphere thanks to work of system of catching of vapors of fuel.
System with the reduced fuel return
On cars the system in which there is no pipeline of return of fuel from the engine in the fuel tank is installed.
Pressure regulator installed in the fuel tank and reduction of length of the pipeline of return of fuel reduces evaporation of fuel by 60–20% in relation to usual fuel system.
Besides, installation of the jet pump in the fuel supply block, provides supply of fuel to the pump, providing steady supply of fuel, at the low level of fuel in a tank. The system provides steady supply of fuel at car inclinations, at the low level of fuel in a tank.
Fuel supply block
The block of supply of fuel is installed in the fuel tank and consists of the following an element and knots:
– the fuel pump with the electric drive;
– pressure regulator;
– fuel filter;
– fuel level sensor;
– fuel-supply lines.
The fuel pump with the electric drive is installed in the fuel tank together with the fuel level sensor. Management of the fuel pump is made by the engine control unit, via the relay of the fuel pump.
The fuel pump via pipelines gives fuel under pressure to the fuel highway and nozzles. Pressure in the fuel highway remains even then when the fuel pump does not work, at the expense of the unilateral valve of the fuel pump located near.
Regulator of pressure of fuel and nozzle
Pressure in fuel system is regulated by pressure regulator.
Giving of tension to nozzles is carried out from the rechargeable battery via the main relay. The amount of the fuel given to an inlet path of the engine is defined by duration of the impulses developed by the control unit of the engine and given on nozzles.
Fuel level sensor
The fuel level sensor consists of the float fixed on the lever and the variable resistor. At change of provision of a float, resistance of the variable resistor in proportion changes. On the basis of a signal from the fuel level sensor, the index of level of fuel in a combination of devices shows amount of fuel in a tank.
Fuel pipelines and hoses
Fuel pipelines and hoses provide transfer of fuel from the fuel tank to the fuel highway and nozzles and return excess fuel in a tank. The fuel pipelines fixed on the bottom of the car need to be examined periodically on lack of dents and deformation as due to narrowing of their passes, restriction of a stream of fuel is possible.
Fuel pipelines and hoses also provide transfer of vapors of fuel from the fuel tank to a canister with absorbent carbon where they gather at the switched-off engine. After launch of the engine and warming up up to the working temperature, the control unit of the engine opens the electromagnetic valve, and fuel vapors from a canister come to the engine and are burned.
The fuel highway provides supply of fuel to each nozzle and is established on an inlet collector.
Now, the regulator of pressure of fuel is not located on the fuel highway, and installed in the fuel tank.
On the fuel highway the service valve which serves for removal of air after service of the car or launch of the engine is located.