Exhaust gas recirculation system for engine incorporating turbo-supercharger

An exhaust gas recirculation system for an engine incorporating a turbo-supercharger, comprising:

• an intake passage connected to an intake port of an engine, for feeding air into a cylinder of the engine through a compressor housing of said turbo-supercharger;
• an exhaust passage connected to an exhaust port of said cylinder, for discharging exhaust gas into the atmosphere from said cylinder through a turbine housing of said turbo-supercharger;
• an external EGR device including an EGR passage connected at one end thereof to said exhaust passage and connected at the other end thereof to said intake passage, and an EGR valve provided in said EGR passage and adapted to adjust the flow rate of exhaust gas recirculated from said exhaust passage into said intake passage through said EGR passage;
• an internal EGR device for opening an exhaust valve provided at the exhaust port, so as to introduce exhaust gas from said exhaust passage into said cylinder during intake stroke of said cylinder;
• a speed sensor for detecting a speed of said engine;
• a load sensor for detecting a load of said engine;
• and
• a controller for controlling said EGR valve or both said EGR valve and said internal EGR device in accordance with detection outputs from said speed sensor and said load sensor.