Backflow check valve ARV

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The function of the secondary air valve is to prevent backflow of exhaust gases into the secondary air blower or the environment. At the same time, the valve has to ensure that when the secondary air system is in operation, fresh air can flow into the exhaust manifold and uncontrolled inflow of air into the exhaust gas system is avoided outside the operation of the secondary air system. The vacuum controlled check valve (ARV) is a pneumatically operated on-off valve featuring low pressure loss. To activate this valve, vacuum from the intake manifold is supplied by a solenoid valve. The ARV operates on the check valve principle. This will reduce return flows when the valve is open With a view to reducing system costs, an alternative, selfopening valve was developed. This secondary air valve (SLV), shown in Fig. 5, will open as soon as the system pressure generated by the secondary air pump exceeds the valve opening pressure. The SLV enables system complexity to be distinctly reduced because the electrical switch valve, the electrical activation and the complete vacuum lines can be deleted. With this valve type, it is likewise possible to integrate a check or non-return function. The SLV can also be chosen with an enlarged membrane diameter to enhance the actuating force.