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以一台车用电控高压共轨柴油机为样机,研究了柴油机恒转速增转矩、恒转矩增转速两类典型瞬变工况的排气烟度、颗粒数量、氮氧化物NO_x等排放特性。结果表明,增转矩瞬变工况下,柴油机烟度值均呈现先升高、后降低、再趋于稳定的特点,中等转速的烟度值变化剧烈。颗粒数量瞬时升高后,逐渐降低并趋于稳定,中高转速瞬时颗粒数量变化显著。NO_x排放在瞬变过程初期就迅速上升,并趋于稳定。增转速瞬变工况下,柴油机排气烟度在初始阶段迅速上升,后逐渐下降,但中低转矩时变化不显著。高转矩时颗粒数量初期出现一个尖峰后迅速下降,而低转矩时颗粒数量持续增加且较高。NO_x排放呈现先增加、后迅速下降的特点,表明了转速瞬变过程对缸内燃烧过程的复杂影响。
Taking a vehicle with electric high pressure common rail diesel engine as a prototype, the exhaust smoke density, particle number, NOx and NO x emission of two typical transient conditions of constant speed and constant torque of diesel engine were studied. characteristic. The results show that under the condition of transient torque transient, the smoke smoke values of diesel engine first increase, then decrease, and then tend to be stable. The smoke smoke value changes rapidly at medium speed. After the number of particles increases instantaneously, it gradually decreases and tends to be stable. The number of instantaneous particles changes significantly at middle and high speeds. NO_x emissions rapidly increased in the early transient and stabilized. Increasing speed transient conditions, the diesel exhaust smoke rose rapidly in the initial stage, then gradually decreased, but the change was not significant at low torque. When the torque is high, the number of particles decreases sharply after a spike, while the number of particles continues to increase and increases at low torque. NO_x emission first increased, then decreased rapidly, indicating the speed transient process of combustion in the cylinder complex impact.