Air flow control valve

Claim 1

In an internal combustion engine system in which the unburned component in discharge gas is burned in a catalytic converter mounted downstream of an exhaust pipe and the resulting gas is discharged to the atmosphere and including an engine having an intake manifold and having an exhaust manifold connected to the exhaust pipe, means for controlling the flow of secondary air comprising, in combination: an air pump for supplying secondary air; first and second two-position changeover valves, said first twoposition changeover valve being connected to provide secondary air from said air pump to a suction port of said second changeover valve in a first position and to provide secondary air to the exhaust pipe upstream of the catalytic converter in a second position, and said second two-position changeover valve coupling said suction port to an exhaust port of a combustion chamber of the engine in a first position and coupling said suction port to the atmosphere in a second position; first pressure responsive means responsively connected to the intake manifold of the engine connected for momentarily switching said first two-position changeover valve from its first position to its second position in response to a first level of vacuum pressure in the intake manifold; a first operating valve responsively connected to said intake manifold and connected for introducing atmospheric pressure acting on said first pressure responsive means in response to a predetermined level of vacuum pressure in said intake manifold, whereby said first two-position changeover valve is maintained in its first position when the vacuum pressure in the intake manifold exceeds the predetermined level; second pressure responsive means responsively coupled to the intake manifold connected for switching said second twoposition changeover valve from its first position to its second position in response to a second level of vacuum pressure being lower than the first level; a second operating valve connected between said second pressure responsive means and the intake manifold for selectively coupling said second pressure responsive means to the intake manifold; and a controller connected to operate said second operating valve, said controller including means for sensing catalytic converter temperature and closing said second operating valve in response to the temperature of the catalytic converter being above a predetermined level, whereby said second two-position changeover valve is maintained in its first position, whereby the flow of secondary air is controlled in response to engine operating conditions.