重型柴油机高原低温起动升速稳定性试验

Stability test of cold starting speed rising stage for heavy duty diesel engine under plateau environment

为提高柴油机高原起动过程中的升速稳定性,以某重型高压共轨柴油机为试验样机,在高原低温环境模拟试验台上,研究重型柴油机在海拔高度1~4km条件下,低温起动过程中的升速阶段稳定性问题,并通过调整喷油量和喷油提前角抑制升速阶段滞速现象的出现,改善柴油机高原低温起动性能。研究结果表明:环境温度为-30℃条件下,在海拔高度2km以上,试验样机在升速阶段出现滞速,随着海拔高度的升高,滞速出现转速降低,滞速比例上升,升速阶段稳定性变差,海拔每升高1km,滞速出现转速降低195r/min,滞速比例升高30.9%;通过适当减小喷油量或增大喷油提前角可抑制升速阶段滞速的出现,试验样机在环境温度-30℃、海拔高度3km下,通过循环喷油量的适当降低,升速阶段滞速比例由方案A的83.7%下降为方案C的68.3%,滞速幅度从75r/min降低为40r/min,滞速出现转速从346r/min升高至385r/min;通过喷油提前角适当增加,滞速比例由方案1的68.3%下降为方案3的34.8%,滞速幅度从40r/min降低为24r/min,滞速出现转速从401r/min升高至638r/min,柴油机高原冷起动升速阶段稳定性得到改善。

To improve the stability of diesel engine in the speed rising stage of starting process in plateau, taking a heavy duty diesel with a high pressure common rail system as test prototype, the stability of heavy duty diesel in cold starting speed rising stage was investigated at the altitude from 1 to 4 km by a test platform with simulated environment of plateau and low temperature. Moreover, the cold starting performance of engine in the environment was improved through reducing faltering in the speed rising stage by adjusting the fuel injection mass and the advanced injection angle. The results show that faltering appears in speed rising stage of the test prototype at an altitude of over 2 km, under the temperature of -30℃. With the increase of altitude, the speed reduces in faltering stage, the occurrence proportion of faltering rises, and the stability in the speed rising stage becomes poor. With the rising of each 1 km in altitude, speed reduces 195 r/min,and the proportion of faltering increases 30.9 %. The occurrence of faltering in speed rising stage can be prevented by properly reducing injection mass and increasing advanced injection angle. When the cyclic injection mass is properly reduced, for the test prototype under -30℃ at altitude lower than 3 km, the proportion of faltering reduces from 83.7% in scheme A to 68.3% in scheme C, the range of the faltering stage reduces from 75 to 40 r/min, and the speed increases from 346 to 385 r/min. When advanced injection angle is properly increased, the proportion of faltering reduces from 68.3% in case 1 to 34.8% in case 3, the range of which reduces from 40 to 24 r/min, and the speed increases from 401 to 638 r/min. Therefore the cold starting performance of heavy duty diesel engine in the speed rising stage is improved under plateau environment. 4 tabs, 10 figs, 25 refs.