Exhaust system
Exhaust system (OG) consists of exhaust manifolds, exhaust pipes, catalytic converters, mufflers and an exhaust pipe.
Exhaust emission control systems
The principle of operation of the engine management system is designed in such a way as to get the most out of the engine with minimal fuel consumption and the content of toxic components in the exhaust gas. The vehicles in question are fitted with a fuel vapor recovery system (EVAP, petrol models only), crankcase ventilation system (PCV), exhaust gas circulation system (EGR) and a system for mixing additional air into the exhaust gas (SAI) in order to accelerate the output of an unheated catalytic converter to the operating level (only models with M60 and M73 engines).
Controlled crankcase ventilation system (PCV)
To eliminate leakage of unburned hydrocarbons into the atmosphere, the engine is completely sealed. Gases and oil vapors formed in the crankcase are fed into the intake manifold and burn in the cylinders along with the fuel.
Gases are removed from the crankcase due to the pressure difference in the crankcase and inlet pipeline (pressure in the crankcase is higher).
Evaporative Emission System (EVAP)
The EVAP system is designed to reduce the emission of unburned hydrocarbons into the atmosphere. The filler neck of the fuel tank is hermetically sealed with a cap. The charcoal absorber collects fuel vapors that form in the tank while the car is parked and is held there until the absorber purge begins at the signal from the control unit. During the purge, fuel vapors are fed through the purge valve into the intake manifold, where they are mixed with the working mixture and then burned in the usual way in the combustion chambers.
To ensure normal operation of the engine at idle and during warm-up, the control unit keeps the valve closed. This prevents unburned fuel from entering the catalytic converter (mixture is too rich at high idle). After the engine warms up, the valve begins to open and close, regulating the supply of fuel vapor to the intake tract.
Because diesel fuel is hardly volatile, diesel models do not use an activated carbon filter. Air is removed from the fuel tank directly to the atmosphere.
Exhaust gas recirculation system (EGR)
This system reduces the amount of NOx in the exhaust gases. To do this, a small part of the exhaust gas is fed into the intake manifold through a special valve. The valve of the recirculation system is controlled by the control unit.
Catalytic converter and lambda probes
To reduce the amount of harmful emissions into the atmosphere, three-function catalytic converters are integrated into the exhaust system. The fuel injection control system has feedback, which includes lambda probes that constantly inform the control unit about the composition of the exhaust gas. Depending on the received data, the control unit corrects the quality of the mixture supplied to the combustion chambers and, thus, optimizes the conditions for fuel combustion.
The working surface of lambda probes is sensitive to changes in the oxygen content in the exhaust gas. Depending on its concentration, the output voltage of the sensor changes. If the mixture is too rich (the oxygen content in the exhaust gas is very low), the lambda probe emits low voltage signals. The voltage increases as the mixture becomes leaner and the oxygen content of the gases increases. The converter works most efficiently with the optimal composition of the combustible mixture (14.7 parts of air to 1 part of fuel).