Combustion type power tool having fin for effectively cooling cylinder

A combustion-type power tool comprising:

• a housing having one end and another end and defining an axial direction;
• a head portion disposed at the one end;
• a cylinder disposed in and fixed to the housing, the cylinder having a peripheral wall which defines a peripheral direction, the cylinder having one axial end and another axial end, the one axial end being closer to the one end than the another axial end is, the peripheral wall having an inner peripheral surface which defines an inner space and having an outer peripheral surface opposite to the inner peripheral surface, the peripheral wall being formed with an exhaust hole at a first axial position;
• a piston reciprocally movable in the axial direction between a top dead center and a bottom dead center and slidable in contact with the inner peripheral surface, the top dead center being closer to the one end than the bottom dead center is, the piston dividing the inner space into an upper space and a lower space, the upper space being closer to the one end than the lower space is;
• a combustion-chamber frame disposed in the housing and movable in the axial direction, the combustion-chamber frame being abuttable on the head portion to provide a combustion chamber in cooperation with the head portion and the piston, the piston allowing the combustion chamber to be in fluid communication with an atmosphere through the upper space and through the exhaust hole when the piston is located at the bottom dead center;
• and
• a fin disposed at the outer peripheral surface and including:
• a first row of fins arranged in the peripheral direction and located at a second axial position;
• and
• a second row of fins arranged in the peripheral direction and located at a third axial position, the second axial position being closer to the one axial end than the third axial position is, the first row of fins and the second row of fins being arranged alternately in the peripheral direction.