What is a car secondary air system?

Vehicle Secondary Air System

In gasoline engines, the injection of secondary air into the exhaust system is a proven method of reducing harmful emissions. During cold starts. A reliable cold start gasoline engine is known to require a rich air-fuel mixture. This mixture contains excess fuel. During a cold start, ignition produces large amounts of carbon monoxide and unburned hydrocarbons. Since the catalyst has not yet reached operating temperature, harmful exhaust gases can be released to the atmosphere. Reduce the content of harmful substances in the exhaust gases during cold start of the engine. Atmospheric air is supplied to the exhaust manifold in close proximity to the exhaust valves. Use of a secondary air system, also called an optional air supply system.

The working process

This leads to additional oxidation or combustion of harmful substances in the exhaust gases. It produces harmless carbon dioxide and water. The heat generated by this process further heats the catalyst and oxygen sensors. This reduces the start time for their effective work. The secondary air system has been used for cars since 1997. Due to the improvement of the fuel injection system and engine management system. The secondary air supply system is gradually losing its significance. The design of the secondary air supply system includes a secondary air pump, a secondary air supply valve and a control system. The secondary air pump is an electric driven radial fan. Atmospheric air enters the pump through the air filter channel.

Vacuum Valve Operation

Air can be drawn into the pump directly from the engine compartment. In this case, the pump is equipped with its own built-in air filter. A secondary air supply valve is installed between the secondary air pump and the exhaust manifold. It combines control and control valves. The non-return valve prevents exhaust emissions and condensation from the exhaust system. This protects the pump from secondary air from damage. The shut-off valve supplies secondary air to the exhaust manifold during a cold start. The secondary air valve works differently. Vacuum, air or electricity. The most commonly used actuator is a vacuum valve. It is controlled by an electromagnetic changeover valve. The valve can also be actuated by pressure. It is generated by a secondary air pump.

Secondary Air System

The best valve is the one with electric drive. It has a shorter reaction time and is resistant to contamination. The secondary air system does not have its own control system. It is included in the engine control circuit. The actuators of the control system are the motor relay, the secondary air pump and the vacuum line solenoid changeover valve. Control actions on the drive mechanisms are formed on the basis of signals from oxygen sensors. Coolant temperature sensors, mass air flow, crankshaft speed. The system is activated when the engine coolant temperature is between +5 and +33 °C and works for 100 seconds. Then it turns off. At temperatures below +5 °C the system is inactive. When you start a warm engine idling, the system can be turned on briefly for 10 seconds. Until the engine reaches operating temperature.

Questions and answers:

What is a secondary air pump for? This mechanism supplies fresh air to the exhaust system. The pump is used at the time of a cold start of the internal combustion engine in order to reduce the toxicity of the exhaust.

What is secondary air? In addition to the main atmospheric air, an additional supercharger is installed in some cars, which supplies air to the exhaust system so that the catalyst warms up faster.

Which element is designed to supply additional air to the combustion chamber? For this, a special pump and a combination valve are used. They are installed in the exhaust manifold as close to the valves as possible.