Internal combustion engine provided with precombustion chamber

An internal combustion engine comprising:

• a cylinder;
• a cylinder head;
• a piston reciprocably disposed in said cylinder;
• a main combustion chamber defined by said piston, said cylinder, and said cylinder head;
• a precombustion chamber in said cylinder head, said precombustion chamber having a longitudinal axis;
• an ignition plug in said precombustion chamber;
• a fuel injection nozzle in said precombustion chamber;
• means defining a passage communicating said main combustion chamber and said precombustion chamber, one end of said passage opening into said main combustion chamber and the other end thereof opening directly into one end of said precombustion chamber in a direction directly toward said ignition plug, said passage having a cross-sectional area of 1 to 10% of that of said cylinder;
• said fuel injection nozzle is positioned adjacent the other end of said precombustion chamber;
• said ignition plug is positioned between said passage and said fuel injection nozzle;
• and
• means for producing a plurality of substantially circular swirl flows of air, the centers of which are spaced from each other along the longitudinal axis, in the precombustion chamber and for reducing the velocity of the flows in the precombustion chamber, said means comprising:
• said precombustion chamber having its longitudinal axis inclined relative to the axis of the cylinder and being oval in longitudinal cross-section;
• and
• said passage being substantially tangentially disposed relative to the inner surface of the precombustion chamber and being inclined relative to the axis of said cylinder whereby the swirl flows produced in the precombustion chamber interfere with each other as a result of their spaced centers to decrease the velocity of the swirl flows so that flame propagation of a fuel mixture charge is lowered and the amount of NO.sub.x in exhaust gas is reduced.