Catalytic converter function
Catalytic converter is a purifying device outside the engine, which can purify carbon monoxide (CO), hydrocarbons (HC), hydrocarbons (HC) and nitrogen oxides (NO) emitted by cars. Catalytic converters that can only purify CO and HC are oxidation-type catalytic converters;
The catalytic converter that can purify the environmental pollution of CO, HC and NO is a three-way catalytic converter.
The outermost part of the catalytic converter is a stainless steel shell, and the inside is a catalyst carrier. The catalyst carrier can be divided into a pit-shaped carrier made of cordierite, a metal carrier or a granular carrier (Figure 1). The outside of the carrier is coated with a catalyst. The catalyst used in the three-way catalytic converter is generally platinum (Pt), palladium (Pd), and rhodium (Rh), and alkali metal oxides are added as additives. In order to improve the stability of the catalyst, the catalyst is also added Earth oxide lanthanum (La), cerium (Ce), etc. (Figure 2).
The catalytic converter uses the residual oxygen in the exhaust gas and the temperature of the exhaust gas to carry out an oxidation-reduction reaction on the surface of the catalyst to turn harmful substances CO, HC and NO into harmless substances, thereby reducing environmental pollution and improving air quality.
Precautions:
1. Do not use leaded gasoline.
2. Do not run rapidly for a long time (open loop control state).
3. Don't let the engine speed suddenly increase or decrease.
4. The ignition time should not be too late.
5. Can not start for a long time.
6. Do not pull out the high-voltage line for a long time to test the fire.
7. When measuring the cylinder pressure, unplug the central control connector of the fuel pump to stop the fuel injector from injecting fuel into the cylinder.
8. When a cylinder is found to work poorly, stop the machine in time for inspection and troubleshoot.
9. Avoid many factors that cause the mixed gas to be too thick, such as poorly shutting off the fuel injector, failure of the fuel pressure regulator (excessive oil pressure), failure of the oxygen sensor, failure of the air flow sensor, etc.
10. As long as the catalytic converter is used correctly, it generally does not require maintenance, so do not disassemble it casually. If it needs to be replaced, it must be matched with the engine.
