6-4-sistemy-vypuska-i-snizheniya-toksichnosti-otrabotavshikh-gazov.html

6.4. Systems of release and decrease in toxicity of the fulfilled gases

General information

System of release of OG

The system of production of the fulfilled gases (FG) consists of final collectors, reception pipes, catalytic converters, mufflers and an exhaust pipe.

Systems of decrease in toxicity of the fulfilled gases

The principle of functioning of a control system of the engine is constructed so that to receive the maximum return from the engine at the minimum fuel consumption and the maintenance of toxic components in OG. On the considered cars system of catching of fuel evaporations (EVAP, only petrol models), the system of ventilation of a case (PCV), system of circulation of OG (EGR) and system of admixture of additional air in OG (SAI) for the purpose of acceleration of a conclusion of not heated-up catalytic converter to operating level are established (only models with M60 and M73 engines).

System of the operated ventilation of a case (PCV)

For elimination of leak of not burned down hydrocarbons in the atmosphere the engine is completely sealed. The gases and vapors of oil which are formed in a case move in the inlet pipeline and burn down in cylinders together with fuel.

Gases are removed from a case at the expense of pressure difference in a case and the inlet pipeline (pressure in a case is higher).

System of catching of fuel evaporations (EVAP)

The EVAP system is intended for decrease in emission in the atmosphere of not burned down hydrocarbons. The jellied mouth of the fuel tank is hermetically closed by a cover. In a coal absorber the fuel vapors which are formed in a tank during the parking of the car gather and keep there until on a signal of the control unit the absorber purge does not begin. During a purge of couple of fuel move via the purge valve in the inlet pipeline where they mix up with working mix and further burn down usually in combustion chambers.

For ensuring normal operation of the engine on single turns and during warming up the control unit holds the valve closed. Thus hit of not burned down fuel in the catalytic converter (is prevented at the raised idling turns mix of a pereobogashchen). After warming up of the engine the valve begins to open and be closed, regulating supply of vapors of fuel to the inlet highway.

Since diesel fuel to a trudnoletucha, on diesel models the filter with absorbent carbon is not used. Removal of air comes from the fuel tank directly in the atmosphere.

System of recirculation of OG (EGR)

This system allows to reduce the number _{of NOx} in the fulfilled gases. For this purpose a small part of OG moves in the inlet pipeline via the special valve. The valve of system of recirculation is controlled by the control unit.

Catalytic converter and lambda probes

For decrease in number of harmful emissions in the atmosphere three-functional catalytic converters are built in system of release of OG. The control system of injection of fuel has feedback which included a lambda probes, OG which are constantly informing the control unit on structure. Depending on the obtained data, the control unit corrects quality of the mix given to combustion chambers and, thus, optimizes fuel combustion conditions.

The working surface a lambda probes is sensitive to change of content of oxygen in OG. Depending on its concentration the output tension of the sensor changes. If mix of a pereobogashchen (content of oxygen in OG very low), the lambda probe gives signals with low voltage. Tension increases in process of impoverishment of mix and increase in content of oxygen in gases. Most effectively the converter works at optimum composition of gas mixture (14.7 parts of air for 1 part of fuel).