| 摘要 |
PURPOSE:To enable the intake and exhaust valves to be of a larger diameter by placing a combustion chamber in such a manner that it shifts to the exhaust port side with respect to a cylinder, and then providing a notch, which forms an operating space for the exhaust valve, on a place where it faces the exhaust valve in the neighborhood of the touching section between the cylinder and a cylinder head. CONSTITUTION:A combustion chamber 12 is placed so that it shifts to the exhaust port 15 side with respect to a cylinder 11. Thereby, the moving area of an intake valve 16 is set up on the inside from the internal surface 11a of the cylinder 11. In addition, a notch 18, forming an operating space for an exhaust valve 17, is provided on a place where it faces the exhaust valve 17 in the neighborhood of the touching section between the cylinder 11 and a cylinder head 13. The notch 18 is formed in front of the moving direction of the exhaust valve 17 so that it extends from the outermost edge of the exhaust port 15 along the moving direction of the exhaust valve 17. And further, it is formed into a circular-arc shape having a radius of curvature a little larger than the outside diameter of the valve element 17a of the exhaust valve 17. Moreover, its depth is set up so that a subscribed clearance can be formed between it and the peripheral edge of the valve element 17a when the exhaust valve 17 is caused to open. |
