METHOD FOR ENABLING VARIABLE COMPRESSION RATIO AND VARIABLE AIR-FUEL RATIO FOR INTERNAL COMBUSTION ENGINE

The present invention provides a method for realizing variable compression ratio and variable air-fuel ratio of an internal combustion engine, the method comprising the following steps: dividing an air intake volume in a cylinder into a first air intake volume and a second air intake volume, designing a compression ratio according to the first air intake volume and opening a throttle to enable the air intake volume to reach the first air intake volume; increasing the opening of the throttle to increase the air inflow to enable the second air intake volume to start the intake, the second air intake volume going beyond the first air intake volume, the compression ratio increasing with the increase of the air intake volume, the compression density of a fuel air mixture increasing with the increase of the compression ratio, and the air-fuel ratio reducing with the increase of the compression density of the fuel air mixture; and correcting, by an electronic control unit, a duration of ignition in real time according to a detonation signal fed back by a knock sensor, and controlling the fuel-injection quantity in real time to ensure the compression density required by the combustion of a lean fuel air mixture.