Method and device for forming mixture gas in direct injection type internal combustion engine

A mixture gas forming device for a direct injection type internal combustion engine, which comprises:

• a piston with a recess forming a combustion space;
• air intake means having air swirling means, for supplying swirling intake air into said combustion space at a swirl speed in conformance to the speed of said internal combustion engine;
• and
• an intermittent swirl injection nozzle for spraying fuel into said swirling intake air in said combustion space at a fuel spray angle, defined as the angle of the substantially conical spray pattern defined by said fuel, varied in response to said engine speed, said intermittent swirl injection nozzle comprising:
• a valve body having a valve hole formed therein and a bottom portion with a valve seat and an injection hole;
• a needle valve slidably fitted in said valve hole, for opening and closing said injection hole;
• at least one tangential passage for swirling fuel to be supplied to said combustion space when said needle valve is lifted;
• and
• means for changing the area of a nozzle gap between said valve body and said needle valve to change the quantity of fuel to be supplied through said nozzle gap relative to the quantity of fuel to be supplied through said tangential passage in response to said engine speed, said nozzle gap being provided in at least one of said valve hole and said needle valve near said tangential passage and at a part where said needle valve is slidably fitted in said valve hole,
• thereby allowing said fuel to float in said combustion space substantially without adhering to a wall of said combustion space.