| 摘要 |
A six-stroke cycle engine comprising: an intake passage (10) having a downstream end connected to a combustion chamber (6) and including no throttle valve provided therein; and an exhaust passage (15) having an upstream end connected to the combustion chamber (6) and including a catalyst (16) provided in the midway. The six-stroke cycle engine includes a first valve configured to open/close the intake passage (10), and a second valve (4) configured to open/close the exhaust passage (15). The six-stroke cycle engine includes a valve gear (8) configured to operate the first valve and the second valve so that an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are executed in the order named, and to operate only the first valve so that a scavenging intake stroke and a scavenging exhaust stroke are executed in the order named next to the exhaust stroke. The valve gear (8) includes a variable valve mechanism (9) capable of continuously changing an opening/closing timing and a lift amount of the first valve. The variable valve mechanism (9) controls an intake air volume in the intake stroke. Pumping loss can be reduced while preventing fresh air from being discharged to the exhaust passage (15) in the scavenging exhaust stroke. |
