Screw air inlet pipe of diesel engine

The utility model discloses the technical proposal of the screw bending-surface structure improvement for the air inlet pipe of a direct-injection diesel engine. The scheme is that the improvement is conducted on the primary structure foundation of the screw air inlet pipe of a diesel engine, the dummy-club radial dimension of a valve conduit is reduced appropriately, and the screw bending surface and the arc-shaped incline are prolonged as much as possible; the screw bendinig surface is enlarged and the arc-shaped incline is lengthened, which is beneficial for further improving the flow velocity of the air eddy, the air input is increased, and the flow direction of the air eddy is improved at the same time. The optimum scheme is that the screw bending surface and the arc-shaped incline are extended to the two third parts downward between the convex table top of the valve guide and the valve seat of the valve.