Combustion device for an engine and method for designing a piston

A combustion device for an engine, comprising a cylinder head, a cylinder block cooperating with the cylinder head, and a piston disposed in the cylinder block;

• wherein
• the cylinder head comprises an intake valve setting region and an exhaust valve setting region;
• a surface of the piston adjacent to the cylinder head comprises a first concave surface and a squeezing surface adjacent to the first concave surface, and the squeezing surface comprises a first squeezing surface corresponding to the intake valve setting region and a second squeezing surface corresponding to the exhaust valve setting region;
• a combustion chamber is formed between the first concave surface and the cylinder head;
• and
• the second squeezing surface comprises a flow guide groove, the flow guide groove comprises two first notches facing the combustion chamber, the two first notches of the flow guide groove are arranged symmetrically with respect to a first center line of the piston, and the first center line is perpendicular to a dividing line between the intake valve setting region and the exhaust valve setting region;
• wherein
• the flow guide groove comprises a first sidewall and a second sidewall, a first end of the first sidewall and a first end of the second sidewall form one first notch of the two first notches, and a second end of the first sidewall and a second end of the second sidewall form another first notch of the two first notches;
• the first sidewall comprises a first sub-sidewall, a second sub-sidewall, and a third sub-sidewall that are connected in sequence, the second sidewall comprises a fourth sub-sidewall, a fifth sub-sidewall, and a sixth sub-sidewall that are connected in sequence, the first sub-sidewall is disposed opposite to the fourth sub-sidewall, the second sub-sidewall is disposed opposite to the fifth sub-sidewall, and the third sub-sidewall is disposed opposite to the sixth sub-sidewall;
• and
• the first sub-sidewall and the third sub-sidewall are arranged symmetrically with respect to the first center line, the fourth sub-sidewall and the sixth sub-sidewall are arranged symmetrically with respect to the first center line, the second sub-sidewall is arranged symmetrically with respect to the first center line, and the fifth sub-sidewall is arranged symmetrically with respect to the first center line;
• and
• wherein the first sub-sidewall is parallel to the fourth sub-sidewall, and the third sub-sidewall is parallel to the sixth sub-sidewall;
• and
• an angle between the first sub-sidewall and the first center line is a, wherein 0°≤a<60°.