The inlet and outlet cones with pipes and mounting flanges, as well as heat reflectors holding the ceramic lining, are welded to the stainless steel catalytic converter body. The entire internal volume of the body is occupied by a ceramic porous monolith - a catalyst, fixed with rings or a stainless steel mesh. The catalyst is a filter in which the entire internal and external surface of the pores that come into contact with gases is covered with a very thin layer of alloy containing platinum, rhodium and palladium. The porous catalyst has a large surface area covered with this alloy of very expensive metals, which is mainly what determines the high price of catalytic converters.
The neutralizer is where a reaction occurs that converts potentially hazardous hydrocarbons and carbon monoxide in the exhaust gases into harmless gases and water vapor.
On all models with a neutralizer, the fuel supply system is a closed-loop system, i.e. based on the signal from the lambda sensor installed in the exhaust system, the control unit constantly optimizes the composition of the fuel-air mixture. Depending on the oxygen content in the exhaust gases, the lambda sensor induces a voltage of 0.1 V (high oxygen, lean mixture) up to 0.9 V (low oxygen, rich mixture). Based on this data, the engine control unit changes the injector opening time and the fuel-air mixture ratio. In order for the combustible mixture to burn completely and the exhaust gases to be free of harmful substances, there must be 1 part fuel per 14.7 parts by weight of air.
The catalytic converter operates effectively at temperatures of +300…+800°C.
Operation of vehicles with a catalytic converter
The neutralizer is a reliable and simple device that does not require maintenance. In order for its service life to be maximum, the following requirements must be met.
Do not use leaded gasoline in a vehicle equipped with a catalytic converter, as the lead will coat the precious metals in the catalytic converter grid, reducing their effectiveness and ultimately causing damage to the converter.
Always keep the ignition and fuel systems in good condition.
Do not operate the vehicle with a faulty ignition system until the fault has been corrected.
If the engine control indicator light comes on while the engine is running, you should contact a service station as soon as possible. If the engine control system is damaged, then in addition to increased fuel consumption and deterioration of the engine's dynamic characteristics, the catalytic converter may fail.
Do not start the engine by towing.
Do not turn off the ignition at high engine speed.
Do not use fuel or motor oil additives as they may contain substances that can damage the catalytic converter.
Do not operate the vehicle if blue smoke is emitted from the exhaust pipe.
After the engine has stopped, the exhaust system continues to emit heat for a long time, so you should avoid parking your car on grass and dry leaves.
Remember that the neutralizer is fragile, so avoid impacts when removing it or other components of the exhaust system.
The service life of a catalytic converter on a well-adjusted car is 100–160 thousand km of vehicle mileage.