| 摘要 |
PURPOSE:To improve intake efficiency throughout a wide range, according to the method wherein an intake valve is shifted by cams for a low speed and a high speed for opening and closing operation, the length of an intake passage is shifted during low speed running or high speed running, and two shifting operation rotation speeds are differed from each other. CONSTITUTION:A cam 13A for a low speed and a cam 13B for a high speed are disposed in juxtaposition on a cam shaft 10, and during low speed operation, an intake valve 3 is operated by a locker arm 15A brought into contact with the cam 13A for a normally low passed. During high speed running of an engine, a traveling plunger 17 of a locker arm 15B, normally brought into contact with the cam 13B for a high speed and swung, is locked through sliding of a lock member 19, and the plunger presses the end of a screw 26 to directly swing the locker arm 15A for opening and closing operation for a high speed. Meanwhile, an on-off valve 34 is located in an intake passage 32, and the length of an intake line is substantially shortened by opening the on-off valve 34 during a middle speed before operation of the cam 13B for a high speed. |
