Two-cycle combustion engine having two-staged piston

Abstract

To provide a two-cycle combustion engine having a two-staged piston, which is simple in structure and inexpensive and in which an undesirable blow-off phenomenon of the air-fuel mixture can be avoided effectively, the two-cycle combustion engine includes a cylinder block 1 having a two-staged cylinder bore defined therein and having a reduced diameter bore portion 1a and a large diameter bore portion 1b, and a two-staged piston 10 having a reduced diameter piston portion 10a and a large diameter piston portion 10b and drivingly accommodated within the two-staged cylinder bore. An annular auxiliary chamber 11 is defined between the large diameter bore portion 1b of the two-staged cylinder bore and the reduced diameter piston portion 10a of the two-staged piston. The two-cycle combustion engine also includes an air passage 24 for introducing an air mixed with oil into a crank chamber 29, an air-fuel mixture passage 21 for introducing the air-fuel mixture into the auxiliary chamber 11, a scavenge air passage 30 for supplying the air within the crank chamber 29 into a combustion chamber 2, and an injection passage 70 for injecting the air-fuel mixture within the auxiliary chamber 11 into the combustion chamber 2 from an inner peripheral surface of the cylinder block 1 in a direction oriented substantially diagonally upwardly.

Dependencies are inferred from the claim text.