The described system includes an exhaust gas catalytic converter, a crankcase ventilation system and a gasoline vapor recovery system.
Exhaust gas control is carried out using a catalytic converter and two oxygen concentration sensors. These sensors provide feedback through the engine injection computer. One sensor is screwed into the top of the exhaust manifold, the other is located behind the catalytic converter. The ECU regulates the composition of the mixture, creating optimal operating conditions for the converter. The catalytic converter consists of a cylinder with a fine mesh coated with catalytic material through which the exhaust gases pass. The catalyst provides a high rate of oxidation of harmful carbon oxides (SO), unburned hydrocarbons and soot, thereby reducing the release of toxic products into the atmosphere.
The oxygen concentration sensor sends a voltage signal to the ECU, which varies depending on the oxygen concentration in the exhaust gases: a low voltage corresponds to a low oxygen level, with a lean mixture and an increase in the oxygen concentration in the exhaust gases, the voltage increases.
Voltage peaks at 14.7 parts stoichiometric (by weight) air and 1 part fuel. Around this value, the voltage coming to the ECU from the sensor varies over a wide range, changing the width of the injector opening pulse.
The crankcase ventilation system reduces the release of unburned hydrocarbons from the crankcase to the atmosphere. The system is closed, gases and oil vapors are extracted from the crankcase and fed into the intake manifold through the wire mesh oil separator for post-combustion during normal combustion in the cylinders.
In all engine operating modes, crankcase gases are removed under the action of increased pressure in the crankcase.
To ensure the correct operation of the system, the hoses and calibrated bushings must be cleaned periodically.
The EVAP system minimizes the release of unburned fuel vapors into the atmosphere. The fuel tank is vented to the atmosphere through a carbon adsorber installed in the front right part of the engine compartment behind the bumper support. The adsorber captures fuel vapors from the tank when the car is parked and stores them until the engine is started and warmed up. The purge valve, at the command of the computer, will open, and the vapors will enter the cylinders through the intake manifold, where they will burn out in the usual way.
Figure 3.113. Scheme of the fuel vapor recovery system: 1 - intake manifold; 2 - solenoid valve of the fuel vapor recovery system; 3 - adsorber; 4 - fuel tank; M - hole for communication with the atmosphere; A, B - connecting hoses
The scheme of the system operation is shown in Figure 3.113, the adsorber is shown in Figure 3.114.
Figure 3.114. Adsorber: 1 - pipeline from the fuel tank; 2 - solenoid valve for adsorber purge; 3 - pipeline to the intake manifold; 4 - hole for communication with the atmosphere