Combustion-type power tool having ignition proof arrangement

A combustion-type power tool comprising:

• a housing having one end;
• a cylinder head disposed at the one end and formed with a fuel injection passage;
• a cylinder disposed in and fixed to the housing, the cylinder defining an axial direction;
• a piston slidably disposed in the cylinder and reciprocally movable in the axial direction;
• a combustion chamber frame disposed in the housing and movable in the axial direction, the combustion chamber frame being abuttable on the cylinder head to provide a combustion chamber in cooperation with the cylinder head and the piston;
• a fan rotatably disposed in the combustion chamber for agitating and mixing an air with a combustible gas injected into the combustion chamber through the fuel injection passage;
• and
• an ignition unit comprising an ignition plug exposed to the combustion chamber and having a tapered tip end portion providing an acute angle of less than or equal to 45 degrees, and an ignition ground that generates a spark between the ignition plug and the ignition ground to ignite a mixture of air and the combustible gas, to thus provide a fire.