Patent ID: 8915219

Claim:
A working machine engine comprising: an engine body having a cylinder block in which a cylinder is provided, a cylinder head provided above the cylinder block and a crank case provided below the cylinder block; a crank shaft that has a first end to which a working machine can be coupled and is rotatably supported by the crank case; a casing that covers an outer surface of the engine body; a fan section that is coupled to a second end opposite to the first end of the crank shaft and generates flow of cooling air in the engine body by rotation of the crank shaft; a cooling air flow passage that is provided between the engine body and the casing to allow the cooling air having passed through the fan section to flow through from a surface of the engine body facing the second end of the crank shaft to a surface of the engine body facing the first end of the crank shaft, the first end of the crank shaft being located in an operator side; an auxiliary fan section that is coupled to the first end of the crank shaft and generates flow of air by rotation of the crank shaft, the auxiliary fan section being smaller in size than the fan section; a centrifugal clutch to which the working machine can be coupled, the centrifugal clutch being connected to the first end of the crank shaft; and an auxiliary air flow passage configured to allow the air having passed through the auxiliary fan section, the auxiliary air flow passage being provided between the casing and the surface of the engine body facing the first end of the crank shaft; wherein the auxiliary air flow passage has an outlet in a side surface of the engine body in a direction orthogonal to the crank shaft; the auxiliary air flow section flows air toward the outlet; and the cooling air flow passage joins the auxiliary air flow passage.