Exhaust gas control apparatus

Claim 1

In an exhaust gas control apparatus having an exhaust gas sensor means, disposed in the exhaust system of an internal combustion engine having an engine shaft, for detecting the air-fuel ratio of an air-fuel mixture supplied to the engine, a carburetor supplying an air-fuel mixture to the engine having main and slow systems and an air cleaner upstream of the carburetor, temperature detector means for detecting a non-warm condition of the engine, actuator means disposed in the main and slow systems of the carburetor for controlling the air-fuel ratio of the mixture supplied to the engine, control circuit means for driving said actuator means in accordance with a signal from the exhaust gas sensor, a 3-way catalyst disposed in the exhaust system at a downstream side of said exhaust gas sensor, idle detector means for detecting an idle condition of the engine, an air supply means for supplying secondary air to the exhaust system at an upstream side of said 3-way catalyst in accordance with a signal from the temperature detector means for detecting the non-warm condition of the engine, the improvement wherein said air supply means comprises a diaphragm type fuel pump means, having a diaphragm and a rocker arm operatively connected thereto, for being driven by the engine shaft via said rocker arm, said detector means are connected to said control circuit means, said air supply means defining a chamber at one side of the diaphragm and having an air inlet port and air discharge port communicating therewith, change-over solenoid valve means for being driven by said control circuit means in accordance with signals from said detector means and for communicating therethrough said air discharge port with the upstream side of the 3-way catalyst and the air cleaner respectively.