Stroke changing engine stroke switching mechanism

The invention discloses a stroke changing engine stroke switching mechanism. Two axial sides of a camshaft are respectively provided with a bearing. A cam body is arranged on the camshaft. The cam body is composed of four cam sheet bodies. A hemispheric locating groove I is formed in a four-stroke operating mode air inlet cam along the direction from the inner circumferential face to the outer circumferential face; a hemispheric locating groove II is formed in a two-stroke operating mode air outlet cam along the direction from the inner circumferential face to the outer circumferential face; a groove hole, namely a guiding groove, with a circular cross section is formed in the camshaft outer circumferential face corresponding to the locating groove I; and a locating steel ball is arranged inside the locating groove and connected with one end of a spring inside the guiding groove and the other end of the spring is connected with the groove bottom of the guiding groove. Compared with the prior art, the stroke changing engine stroke switching mechanism has the advantages that change on a prior machine is small, a valve timing mechanism transmission portion is not changed, adaptability is strong, switching is rapid and stable and weight is light.