| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce incurring of a pump loss without worsening of combustion during partial load, in a four-cycle gasoline engine. SOLUTION: Both an intake valve and an exhaust valve are provided with a variable valve mechanism to continuously vary and control a valve opening and closing timing together with a working angle. During idling (a) and during high speed (c), the central angle of a valve overlap is situated approximately at a top dead center but during low speed partial load (b), the closing timing of the exhaust valve is more delayed than the top dead center and at the opening timing of the intake valve, it is also more delayed tan the top dead center. At the initial stage of a suction stroke, a cylinder pressure is rendered equal to an exhaust pressure and incurring of a pump loss is reduced. Further, since residual gas does not reversely flow to an intake system, combustion is improved.</p> |
