单向阀对双增压气路中气体流向影响的分析与研究

搭建由双电动增压器与单向阀组成的试验台架并模拟研究单向阀对双增压气路中气体流向的影响规律,以提高电动增压器的补气效率,从而增大公交车柴油机工况突变时的进气量,改善瞬态烟度。通过向两个电动增压器设定不同的转速,分别模拟公交车柴油机的废气涡轮增压器和附加用于急加速补气的电动增压器,研究并分析在气路上设置单向阀前后对双增压气路中气体流向的影响。试验结果表明,电动增压器的流量大于废气涡轮增压器的流量时,出口总流量在无单向阀时大致等于废气涡轮增压器提供的流量,增加电动增压器的流量不会改变出口总流量,电动增压器补气效率低,柴油机的进气量未得到改善。有单向阀时,出口总流量随电动增压器流量增加而增大,电动增压器补气效率高,柴油机的进气量增大;电动增压器的流量小于废气涡轮增压器的流量时,电动增压器与单向阀不影响出口总流量,出口总流量与有旁通气路无单向阀时相同,即电动增压器不工作时不影响原机的进气量。

Research and Analysis on the Air Flow Direction Affected by Check Valve in Pressurization Gas Path of Two Electric Superchargers

A testing rig,consisting of two electric superchargers and a check valve,used to simulate and investigate the air flow direction affected by check valve in pressurization gas path is built.Through this way higher fill gas efficiency of electric supercharger can be achieved,which will give rise to more air inflow of diesel engine at its working condition mutation,improving transient FSN.By setting the speed of the two electric Superchargers respectively,one is used to simulate the turbocharger of the diesel engine of a bus and the other is used to simulate electric supercharger which supplys additional air for a sharp acceleration,to study the air flow direction affected by check valve in pressurization gas path.Testing results indicate that without the check valve,when the flow rate of the electric supercharger is larger than that of the turbocharger,the total flow rate is equal to that of the turbocharger,and it will not increase while increasing flow rate of the supercharger,for the fill gas efficiency of the electric supercharger is low and air inflow is not increased.With the check valve,the total flow rate will increase while increasing flow rate of the supercharger,for higher fill gas efficiency of the electric supercharger is achieved and air inflow is increased.When the flow rate of the electric supercharger is smaller than that of the turbocharger,the total flow rate will not be affected by the electric supercharger while using the check valve and a by-pass comparing to the total flow rate while using a by-pass only,which means the air inflow will not be decreased by the electric supercharger when it stops.