SECONDARY AIR INJECTION SYSTEM OF ENGINE

摘要

Disclosed is a secondary air injection system of an engine, comprising a secondary air injection pump (4), a secondary air combination valve (2), an electromagnetic valve (3), a vacuum air storage tank (6) and a check valve (7), wherein an air inlet of the secondary air injection pump (4) is in communication with an air filter (8), and an air outlet of the secondary air injection pump (4) is in communication with an air inlet of the secondary air combination valve (2); an air outlet of the secondary air combination valve (2) is in communication with an exhaust manifold (1) of the engine; one end of the electromagnetic valve (3) is in communication with the vacuum air storage tank (6), and the other end thereof is in communication with a vacuum chamber of the secondary air combination valve (2); the secondary air injection pump (4) and the electromagnetic valve (3) are respectively connected to an ECU (9) and are controlled by the ECU (9); the other end of the vacuum air storage tank (6) is connected to an intake manifold (5) by means of the check valve (7), so that air in the vacuum air storage tank (6) only flows to the intake manifold (5); and the volume of the vacuum air storage tank (6) is at least five times as large as that of the vacuum chamber. The system can avoid excessive injection of compressed air when the compressed secondary air is injected.