不使用起动机的条件下，在一台4G15缸内直喷汽油机上研究了直接向处于膨胀冲程气缸喷油点火正转直接起动模式和向处于压缩冲程气缸喷油反转后再向膨胀冲程气缸喷油正转的起动模式．结果表明：首次喷油气缸过量空气系数在0．84左右时可以获得最高燃烧压力；正转起动模式处于膨胀冲程气缸活塞初始位置在上止点后105°CA时较为理想，能保证膨胀冲程气缸活塞转过其下止点，从而使起动成功；对于先反转后正转起动模式，处于压缩冲程气缸活塞位置控制在上止点前80°CA时，保证了该活塞反转且不能转过其下止点，其次使处于膨胀冲程的气缸有较多的气体并尽量的被压缩，有利于顺利起动．%The control strategies without starter and inject fuel into cylinder to start engine were studied on a 4G15 direct injection engine. Two starting methods were studied. One is to directly inject fuel into the cylinder at expansion stroke to start the engine and another is to inject fuel into the cylinder at compression stroke to make engine backwardly rotate and then inject fuel into the cylinder at expansion stroke to make engine forwardly rotate. Test results show that the first injection cylinder gives the highest peak in-cylinder pressure at excessive air coefficient of 0.84. In forward starting mode, piston position at 105° CA after top dead center at expansion stroke is ideal, which can ensure the piston at expansion stroke pass the bottom dead center and successfully be started. In backward starting mode, the piston at compression stroke reverses but will not let it to pass the bottom dead center when starting the engine at piston position before 80° CA before top dead center. More air remains in the cylinder at expansion stroke and being compressed will make a successful start.
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