Catalyst temperature control system for internal combustion engines

In a catalyst temperature control system for an internal combustion engine having an intake system, an exhaust system, a catalyst having a catalyst bed and arranged in said exhaust system for purifying noxious components in exhaust gases emitted from said engine, and an exhaust gas recirculation passage connected to said intake system and said exhaust system for returning part of said exhaust gases from said exhaust system to said intake system,

• the improvement comprising:
• temperature detecting means for detecting a temperature of said catalyst bed of said catalyst;
• exhaust gas recirculation amount-increasing means for increasing a recirculation amount of exhaust gases flowing through said exhaust gas recirculation passage, when said temperature of said catalyst bed detected by said temperature detecting means is higher than a first predetermined value;
• and
• air-fuel ratio enriching means for enriching the air-fuel ratio of a mixture supplied to said engine, when said temperature of said catalyst bed detected by said temperature detecting means is higher than a second predetermined time period after said exhaust gas recirculation amount-increasing means started to increase said recirculation amount.