Vehicle emission air injection

In an automotive vehicle emission system having an internal combustion engine, an engine exhaust conduit, a catalytic converter connected to the conduit, an air pump for injecting pressurized air into the exhaust conduit between the engine and the catalytic converter, and an air injection valve fluidly communicating the air pump with the engine exhaust conduit between the catalytic converter and the engine, the air injection valve comprising:

• a valve housing;
• a valve inlet fluidly communicating the valve housing with the air pump;
• a valve outlet fluidly communicating the valve housing with the catalytic converter, the valve outlet having a check valve therein preventing flow from the exhaust conduit through the air injection valve to the air pump;
• a first diaphragm in the housing creating a first chamber in the housing, the first chamber being fluidly exposed to the valve inlet;
• a second diaphragm in the housing having a central disk, the second diaphragm creating a second chamber between itself and the first diaphragm, and the second diaphragm forming a thin chamber between itself and the housing generally opposite the first chamber, the third chamber being vented to the atmosphere;
• a sealing wall located within the housing separating the second chamber from the inlet, the sealing wall having a surface forming a valve seat with the disk of the second diaphragm, dividing the inlet from the second chamber;
• a spring urging the disk of the second diaphragm toward the first chamber;
• and
• a valve stem connecting the first and second diaphragms wherein the air pressure within the second chamber causes a generally equal force on the first diaphragm to move in a first direction as it causes on the second diaphragm to move in a second direction opposite from the first direction, moving the second diaphragm away from the sealing wall.