汽车4冲程内燃机课程设计-精.docVIP

四冲程内燃机设计 摘要 内燃机是一种动力机械，它是通过使燃料在机器内部燃烧，并将其放出的热能直接转换为动力的热力发动机。通常所说的内燃机是指活塞式内燃机。 活塞式内燃机以往复活塞式最为普遍。活塞式内燃机将燃料和空气混合，在其气缸内燃烧，释放出的热能使气缸内产生高温高压的燃气。燃气膨胀推动活塞作功，再通过曲柄连杆机构或其他机构将机械功输出，驱动从动机械工作。内燃机的工作循环由进气、压缩、燃烧和膨胀、排气等过程组成。这些过程中只有膨胀过程是对外作功的过程，其他过程都是为更好地实现作功过程而需要的过程。四冲程是指在进气、压缩、膨胀和排气四个行程内完成一个工作循环，此间曲轴旋转两圈。进气行程时，此时进气门开启，排气门关闭；压缩行程时，气缸内气体受到压缩，压力增高，温度上升；膨胀行程是在压缩上止点前喷油或点火，使混合气燃烧，产生高温、高压，推动活塞下行并作功；排气行程时，活塞推挤气缸内废气经排气门排出。此后再由进气行程开始，进行下一个工作循环。 关键字：内燃机，4冲程，压缩，做功，排气，吸气 Abstract The internal combustion engine is one kind of power generator, it is through causes the fuel at the machine internal ignition, and the heat energy which emits it transforms directly into the power heat engine. The usually called internal combustion engine refers to the internal-combustion reciprocating engine. The internal-combustion reciprocating engine moves back and forth the plunger type to be most common. The internal-combustion reciprocating engine the fuel and the air mixing, in its air cylinder internal combustion, the heat energy which releases causes in the air cylinder to produce the high temperature high pressure fuel gas. The fuel gas inflation impetus piston makes the merit, again through crank link motion gear or other organizations mechanical merit output, actuation follower work. Internal combustion engines operating cycle by processes and so on air admission, compression, combustion and inflation, exhaust is composed. In these processes only then the expansion process is makes the merit outward the process, other processes are to realize well make the merit process, but needs process. The four stroke is refers to, in the air admission, the compression, inflate and exhaust in four traveling schedules to complete an operating cycle, crankshaft rotation two. When intake stroke, this time air intake valve opening, exhaust gate closure; When compressio