配气相位和废气再循环对Atkinson循环发动机泵气损失影响及优化
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摘要
为降低Atkinson循环汽油机泵气功产生的能量损失,采用一台1.0L自然吸气Atkinson循环汽油机一维热力学模型进行计算研究,依次分析了进排气相位和废气再循环(EGR)对泵气损失的影响,在典型小负荷区,推迟进气晚关角(IVC)可以增加进气歧管内压力,降低泵气损失,但当进气早开角在上止点后推迟过大,导致活塞在封闭系统中膨胀负功逐渐增加,泵气损失反而增加,因此可以通过推迟排气晚关角(EVC)来增加气门重叠期,减少活塞在封闭系统中做的膨胀负功;提前排气晚关角,利用活塞在封闭系统中压缩功抵消膨胀功,减少泵气负功。研究发现:当进气晚关角推迟到101°时,泵气损失压力降低到-64.7kPa;推迟排气晚关角到55°,泵气损失压力可以降低到-52.6kPa,同时提前排气晚关角到-45°,可以减少泵气损失压力到-30.4kPa。在保证稳定燃烧的前提下控制EGR阀来调节EGR率,在大负荷时,泵气损失减小收益来自于进气压力的增加和排气压力的降低,随EGR率的增加,泵气损失最多可减少18.8%;在小负荷时,泵气损失减小收益主要来自于进气压力的增加,随EGR率的增加,泵气损失最多可减少14.8%。
To reduce energy loss caused by pumping work in Atkinson cycle gasoline engine,this paper conducted the research on an one-dimensional thermodynamic model of naturally aspirated Atkinson cycle gasoline engine,and analyzed the effect of IVC and EVC on the pumping loss of a naturally aspirated gasoline engine.The results showed that when the intake valve closing time is delayed,the pressure in the intake manifold increases,the pumping loss is reduced to -64.7 kPa when the intake valve closing time is delayed to 101° at low load;however,when the intake valve closing time is delayed too late,the negative expansion power gradually increases and causes pump loss increase.Delaying exhaust closing angle to 55° can increase the valve overlap period and decrease the pumping loss to -52.6 kPa,while advancing exhaust closing angle to -45° can reuse negative compression power and reduce the pumping loss to -30.4 kPa.Then,under the premise of stable combustion,the EGR valve can be controlled to adjust the EGR rate.The results showed that,at high load,the pumping loss gain comes from the increase of inlet pressure and the decrease of exhaust pressure;with the increase of EGR,the pumping loss can be reduced by 18.8%;at low load,the pumping loss gain mainly comes from the increase of inlet pressure,and with the increase of EGR,the pumping loss can be reduced by 14.8% at most.
To reduce energy loss caused by pumping work in Atkinson cycle gasoline engine,this paper conducted the research on an one-dimensional thermodynamic model of naturally aspirated Atkinson cycle gasoline engine,and analyzed the effect of IVC and EVC on the pumping loss of a naturally aspirated gasoline engine.The results showed that when the intake valve closing time is delayed,the pressure in the intake manifold increases,the pumping loss is reduced to -64.7 kPa when the intake valve closing time is delayed to 101° at low load;however,when the intake valve closing time is delayed too late,the negative expansion power gradually increases and causes pump loss increase.Delaying exhaust closing angle to 55° can increase the valve overlap period and decrease the pumping loss to -52.6 kPa,while advancing exhaust closing angle to -45° can reuse negative compression power and reduce the pumping loss to -30.4 kPa.Then,under the premise of stable combustion,the EGR valve can be controlled to adjust the EGR rate.The results showed that,at high load,the pumping loss gain comes from the increase of inlet pressure and the decrease of exhaust pressure;with the increase of EGR,the pumping loss can be reduced by 18.8%;at low load,the pumping loss gain mainly comes from the increase of inlet pressure,and with the increase of EGR,the pumping loss can be reduced by 14.8% at most.
引文
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[2]MIKLANEK L,VITEK O,GOTFRYD O,et al.Study of unconventional cycles(Atkinson and Miller)with mixture heating as a means for the fuel economy improvement of a throttled SI engine at part load[J].SAE International Journal of Engines,2012,5:1624-1636.
[3]GOTO T,ISOBE R,YAMAKAWA M,et al.The new Mazda gasoline engine Skyactiv-G[J].Atzautotechnology,2011,72(6):40-47.
[4]YONEKAWA A,WATANABE O,SEKIYA N,et al.Development of new 2.0lgasoline engine for accord hybrid[J].Honda R&d Technical Review,2013,25(2):26-31.
[5]TAKAHASHI D.Combustion development to achieve engine thermal efficiency of 40%for hybrid vehicles:SAE 2015-01-1254[R].Washington,DC,USA:SAE,2015.
[6]BREHOB D D,AMLEE D R.Effects of inlet air heating and EGR on thermal efficiency of a SI engine at part load[R].Washington,DC,USA:SAE,1990.
[7]SHINAGAWA T,KUDO M,MATSUBARA W,et al.The new toyota 1.2-liter ESTEC turbocharged direct injection gasoline engine[R].Washington,DC,USA:SAE,2015.
[8]HEYWOOD J.Internal combustion engine fundamentals[M].New York,USA:McGraw-Hill Education,1988.
[9]潘锁柱,宋崇林,裴毅强,等.EGR对GDI汽油机燃烧和排放特性的影响[J].内燃机学报,2012(5):409-414.PAN Suozhu,SONG Chonglin,PEI Yiqiang,et al.Influence of EGR on combustion and emissions of a gasoline direct-injection engine[J].Transactions of CSICE,2012(5):409-414.
[10]韩林沛,洪伟,王建军,等.汽油机部分负荷应用热废气再循环实现临界爆震的性能优化[J].西安交通大学学报,2015,49(10):116-122.HAN linpei,HONG Wei,WANG Jianjun,et al.Performance optimization of partial load of gasoline engine at critical knock status using hot exhaust gas recirculation[J].Journal of Xi’an Jiaotong University,2015,49(10):116-122.
[11]胡顺堂.全可变气门机构汽油机泵气损失控制及对燃烧过程的影响[D].天津:天津大学,2009.
[12]PIERIK R J,BURKHARD J F.Design and development of a mechanical variable valve actuation system[R].Washington,DC,USA:SAE,2001.
[13]SAUNDERS R J,ABDUL-WAHAB E A.Variable valve closure timing for load control and the Otto Atkinson cycle engine[R].Washington,DC,USA:SAE,1989.