CAJ | 학술논문

在现有4F20机械式燃油系统柴油机基础上,从机械系统和燃烧系统优化匹配、后处理系统选型等方面入手,进行了满足国Ⅳ排放标准的经济型轻型车用柴油机开发.机械系统设计中,对机体和缸盖的加强筋和冷却水套进行合理布置,有效提高整机刚度和缸套冷却效果,减少变形,并设计了结构紧凑、传动可靠且运转平稳的新型齿轮传动系统.燃烧系统升级优化方面,由直列泵式机械燃油供给系统升级为高压共轨电控燃油喷射系统,重新设计燃烧室形状的同时将压缩比从19.7降低为17.5,并优化燃油油束在燃烧室内的分布.通过燃油喷射、增压与废气再循环参数的协同标定改善了柴油机燃油经济性和排放性能.选用容积占有率为25%和75%的2级氧化催化转化器,对一氧化碳(CO)、碳氢化合物(HC)、可溶性有机成分(soluble organic fractions ,SOF)和颗粒(particulate matter,PM)的净化效率分别达90%、85%、90%和20%.柴油机配套 NHQ6492V3型 SUV 后整车排放测试结果显示:CO、NOx、总碳氢(THC)+NOx 和 PM 排放分别为0.36、0.259、0.328和0.029g/km,距国Ⅳ排放限值有20%以上的裕度,综合油耗为7.217 L/(100km),满足2015年即将实施的中国乘用车燃料消耗第3阶段法规限值.
재현유4F20궤계식연유계통시유궤기출상,종궤계계통화연소계통우화필배、후처리계통선형등방면입수,진행료만족국Ⅳ배방표준적경제형경형차용시유궤개발.궤계계통설계중,대궤체화항개적가강근화냉각수투진행합리포치,유효제고정궤강도화항투냉각효과,감소변형,병설계료결구긴주、전동가고차운전평은적신형치륜전동계통.연소계통승급우화방면,유직렬빙식궤계연유공급계통승급위고압공궤전공연유분사계통,중신설계연소실형상적동시장압축비종19.7강저위17.5,병우화연유유속재연소실내적분포.통과연유분사、증압여폐기재순배삼수적협동표정개선료시유궤연유경제성화배방성능.선용용적점유솔위25%화75%적2급양화최화전화기,대일양화탄(CO)、탄경화합물(HC)、가용성유궤성분(soluble organic fractions ,SOF)화과립(particulate matter,PM)적정화효솔분별체90%、85%、90%화20%.시유궤배투 NHQ6492V3형 SUV 후정차배방측시결과현시:CO、NOx、총탄경(THC)+NOx 화 PM 배방분별위0.36、0.259、0.328화0.029g/km,거국Ⅳ배방한치유20%이상적유도,종합유모위7.217 L/(100km),만족2015년즉장실시적중국승용차연료소모제3계단법규한치.
Based on a 4F20 diesel engine with a mechanical fuel injection system, a high-pressure common rail diesel engine was developed to meet the national stage IV Emission Regulation. The optimization and matching of mechanical, combustion and after-treatment systems were conducted. For the development of the mechanical system, the ribs were added and a separated structure between the cylinder head bosses and the liner was utilized to increase the cylinder block stiffness and to reduce the liner distortion. The geometry of the upper water jacket in the cylinder block was designed to be circular, and its height was increased to match the TDC position of the first piston ring to improve the cooling effect of piston. The installing hole of for the glow plug was added on the base of three-hole layout, and then the coordinates of four holes were optimized. Degassing holes were added at corresponding position in the cylinder head gasket and cylinder head to eliminate dead flow regions and to enhance cooling effect; Coolant passages were set around the injector and above the intake, exhaust ports, and the local maximum temperature of cylinder head was reduced from 469.1K to 457.8K according to the optimized results. A new type of double row gear transmission system was designed which can run compactly and stably at low noise levels. For the optimization of the combustion system, the precise and flexible control of fuel injection timing and amount as well as split injection strategies were achieved by upgrading the mechanical fuel injection system to the BOSCH CRS2.0 electronically controlled high-pressure common rail fuel injection system. The injection pressure was improved significantly (the max pressure could reach up to 160MPa) as a result of the upgrade. The pre-injection can effectively improve the NOx emission about 30% at small and medium load, and low NOx and soot emissions were achieved while maintaining fuel efficiency after the introduction of post-injection at medium load. A big, open shallow combustion chamber was designed and the compression ratio was decreased from 19.7 to 17.5. Fuel spray circumferential distribution was planned according to the principle of equal arc length, also spray axial distribution was optimized, and the ratio of spray coverage volume to effective combustion volume was determined as 54.41%. For the air intake system, a radial-flow turbocharger with an exhaust bleeder valve was chosen to ensure that the compressor had enough safety margins from surge line at low speed, and it could work in highly efficient areas in the medium speed range. After applying the two-stage DOC system whose first and second volume fraction were 25% and 75%, the purification efficiency of CO, HC, SOF and PM reached 90%, 85%, 90% and 20% respectively. The developed diesel engine in this paper was equipped on an NHQ6492V3 SUV. The vehicle emissions test results showed that the emission of CO, NOx, THC+NOx and PM were decreased to 0.36, 0.259, 0.328 and 0.029g/km respectively, which were 20% lower than the national stage IV Emission Regulation limit. The comprehensive fuel consumption was 7.217L/(100 km) and it can meet the Chinese third stage regulation for passenger cars limit which will be implemented in 2015.