| 摘要 |
A variable valve mechanism includes a low-speed cam, a high-speed cam, a low-speed rocker arm driven by the low-speed cam, a high-speed rocker arm driven by the high-speed cam, and a switching mechanism. A cam profile of the high-speed cam is set such that it does not exceed a cam profile of the low-speed cam. During low-speed operation, the switching mechanism links the low-speed and the high-speed rocker arms such that the low-speed cam causes the high-speed rocker arm to rock together with the low-speed rocker arm and to open and close a valve. During high-speed operation, the switching mechanism de-links the low-speed rocker arm and the high-speed rocker arm such that the low-speed cam causes the low-speed rocker arm to rock idly and the high-speed cam causes the high-speed rocker arm to rock independently and to open and close the valve. The cam profile of the low-speed cam is set such that the valve closes later than it does with the cam profile of the high-speed cam.
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