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在降低凸轮转速n_κ或减少喷油量B_μ时,喷孔前压力P_с(喷射压力)下降,是现今柴油机中普遍采用的由凸轮以刚性驱动柱塞的燃油装置固有的缺点。按机车或螺旋浆特性工作的发动机,在同时减少n_к和B_д时,P_с的下降就尤为显著。喷射压力的下降,使燃油与气体的混合和燃烧恶化,从而使发动机的经济指标和可靠性下降。对于大部分时间是在部分工况(其中包括小负荷和空转工况〔1〕)工作的机车发动机来说,这些现象是特别有害的。这时,高增压发动机(如Д70柴油机)是处在最不利的条件下。该种发动机空转时的n_к和Β_ц与全功率时相比,n_κ降低了60～66.6％,B_с降低了90～
The drop in the pressure P_с (injection pressure) before the injection hole when the cam rotation speed n_κ is decreased or the injection amount B_μ is decreased is a drawback inherent in today’s diesel engines in that the fuel is rigidly driven by the cam by the cam. The engine that operates on locomotive or propeller characteristics reduces the P_с especially significantly when both n_к and B_д are reduced. The drop in injection pressure deteriorates the fuel-gas mixture and combustion, resulting in a reduction in the economic indicators and reliability of the engine. These phenomena are particularly detrimental to locomotive engines that work most of the time in some operating conditions, including light-load and idling conditions [1]. At this time, high-pressured engines (such as the Д70 diesel) are under the most unfavorable conditions. The engine idling n_к and Β_ц compared with the full power, n_κ reduced by 60 ~ 66.6%, B_с reduced by 90 ~