Exhaust gas purifying system

An exhaust purifying system for an engine, comprising;

• a. a catalytic converter including a casing, exhaust gas inlet means for providing communication to the casing from an exhaust passageway of an engine, an outlet from the casing communicating with the atmosphere, catalytic means disposed in the casing and including an outer peripheral wall to provide a cooling chamber disposed between an inner circumference of the casing and the outer peripheral wall of the catalytic means, means spacing said catalytic means from the inner circumference of the casing, and an air inlet communicating with the space between the inner circumference of said casing and said catalytic means;
• b. means defining an upstream opening of the catalytic means communicating with the exhaust gas inlet means and defining a downstream opening of the catalytic means communicating with the outlet to provide an inlet chamber between the exhaust gas inlet and the upstream opening of the catalytic means and an outlet chamber between the outlet and the downstream opening of the catalytic means, said exhaust gas inlet and outlet chambers being disposed at mutually spaced ends of said casing and of said outer peripheral wall;
• c. a source of air;
• d. a valve having an inlet communicating with the source of air and having a first outlet communicating with said cooling chamber through said air inlet, whereby air passing into said cooling chamber via said air inlet is in direct heat-exchange contact with the catalytic means;
• and
• e. means, including temperature sensing means for feeding a signal to the valve when the temperature in the catalytic converter is above a predetermined level at which the activity of the catalyst means degenerates, to normally block communication between the source of air and said air inlet via the valve, and to selectively establish communication between the source of air and said air inlet via the valve in response to said electrical signal.