Temperature control of a catalytic exhaust purifier

Claim 1

IN A COMBINATION OF A CATALYTIC EXHAUST PURIFIER WITH A GASOLINE-POWERED INTERNAL COMBUSTION ENGINE ADAPTED TO OPERATE OVER A RANGE OF SPEEDS INCLUDING IDLING SPEED AND A HIGHER SPEED, A PURIFIER INCLUDING A HOUSING CONTAINING OXIDATION CATALYST, A CONDUIT CONNECTING THE EXHAUST OUTLET FROM SAID ENGINE WITH THE EXHAUST PURIFIER SO THAT THE EXHAUST GASES PASS OVER SAID OXIDATION CATALYST, AN AIR IMPELLER TO DELIVER AIR TO SAID CONDUIT BETWEEN THE ENGINE AND THE PURIFIER, MEANS TO CONTROL SAID AIR DELIVERY TO MAINTAIN SAID OXIDATION CATALYST WITHIN THE OPERATING TEMPERATURE RANGE THEREOF AND SUCH THAT THE AMOUNT OF AIR ADMITTED AT IDLING SPEED OF THE ENGINE WHEN THE FLOW OF EXHAUST GASES IS AT A MINIMUM PROVIDES A MAXIMUM WEIGHT RATIO OF AIR TO EXHAUST GASES FLOWING TO SAID PURIFIER WHILE THE AMOUNT OF AIR ADMITTED AT A HIGHER SPEED OF THE ENGINE IS SUCH THAT THE WEIGHT RATIO OF AIR TO EXHAUST GASES FLOWING TO THE PURIFIER IS DECREASED.