Characterization of Particle Emissions of Turbocharged Direct Injection Gasoline Engine in Transients and Hot Start Conditions

Reducing pollutant emissions,particularly soot particles emitted by internal combustion engines,is a major challenge for car manufacturers.In this paper,the experimental setup is a turbocharged three-cylinders gasoline direct injection engine installed on a HORIBA dynamic test driven by a HORIBA STARS computer.The particle-measuring device is a Pegasor Particles Sensor that measures the current carried by previously electrically charged particles.The hot engine stabilized tests,with lambda parameter lower or equal to one,have very low emission levels,unlike dynamic tests.As a consequence,the present paper deals with experiments in transient conditions.Unlike diesel engine,cycle tests show that particulate emissions vary widely.To understand the phenomenon,a simple transient was created and reproduced a hundred times in order to obtain enough data to analyze and compare these different tests.This transient starts from idle to reach the speed of 2000 r/min and 60 N·m in 5 s.To reach this point,it is necessary to stay in full load for about 3 s.The maximum deviations of particles reaches 85%with the standard deviationσ=18%.The cylinder pressure sensor shows significant variations at the very beginning of each transient,i.e.,during the first 500 ms.This kind of result was observed for Worldwide harmonized Light vehicles Test Cycles(WLTC)with a maximum deviations of particles reaching 75%withσ=30%,on Real Drive Emissions Cycle(RDE)with a maximum deviations of particles reaching 45%withσ=22%and for a 300 s Mini-Cycle with a maximum deviations of particles reaching 70%withσ=17%.The Mini-cycle is made up of the five largest accelerations of the WLTP cycle.A complete analysis highlights the importance of filling the first engine cycles.This depends on the opening speed of the throttle,the position of the crankshaft at the beginning of the transient,and the acceleration of the first cycles.But,the NO_(x) sensor shows very slight variations between each test.As a consequence,it appears that the variation of particles emissions is not only related to variation of equivalence ratio but with another setting,which may be the oil consumption.Finally,from these results,it is possible to determine a particle characterization function.It consists of two functions.The first one is the average of the emitted particles level which depends on the engine speed,engine acceleration,engine torque and torque acceleration.The second function,which corresponds to dynamic variations in emissions,mainly depends on oil consumption in the cylinder and on the combustion quality of the first transient engine cycles.

Experimental study of stratified lean burn characteristics on a dual injection gasoline engine

Due to increasingly stringent fuel consumption and emission regulation,improving thermal efficiency and reducing particulate matter emissions are two main issues for next generation gasoline engine.Lean burn mode could greatly reduce pumping loss and decrease the fuel consumption of gasoline engines,although the burning rate is decreased by higher diluted intake air.In this study,dual injection stratified combustion mode is used to accelerate the burning rate of lean burn by increasing the fuel concentration near the spark plug.The effects of engine control parameters such as the excess air coefficient(Lambda),direct injection(DI)ratio,spark interval with DI,and DI timing on combustion,fuel consumption,gaseous emissions,and particulate emissions of a dual injection gasoline engine are studied.It is shown that the lean burn limit can be extended to Lambda=1.8 with a low compression ratio of 10,while the fuel consumption can be obviously improved at Lambda=1.4.There exists a spark window for dual injection stratified lean burn mode,in which the spark timing has a weak effect on combustion.With optimization of the control parameters,the brake specific fuel consumption(BSFC)decreases 9.05%more than that of original stoichiometric combustion with DI as 2 bar brake mean effective pressure(BMEP)at a 2000 r/min engine speed.The NO_(x) emissions before threeway catalyst(TWC)are 71.31%lower than that of the original engine while the particle number(PN)is 81.45%lower than the original engine.The dual injection stratified lean burn has a wide range of applications which can effectively reduce fuel consumption and particulate emissions.The BSFC reduction rate is higher than 5%and the PN reduction rate is more than 50%with the speed lower than 2400 r/min and the load lower than 5 bar.

Estimation of Residual Exhaust Gas of Homogeneous Charge Compression Ignition Gasoline Engine Operating Under Negative Valve Overlap Strategy

To meet the requirements of the homogeneous charge compression ignition gasoline engine’s rapid cylinder exhaust gas rate and accurate control of combustion phasing,a residual exhaust gas rate model was proposed.A heat dissipation model for gas flow in the exhaust passage and exhaust pipe was established,and the exhaust gas was established.Flow through the exhaust valve was considered as an adiabatic expansion process,the exhaust temperature was used to estimate the temperature in the cylinder at the time that the valve was closed,and the cylinder exhaust gas rate was calculated.To meet the requirements of transient operating conditions,a first-order inertial link was used to correct the thermocouple temperature measurement.Addressing this delay problem and modification of the exhaust wall temperature according to different conditions effectively improved the accuracy of the model.The relative error between the calculated results of this model and the simulation results determined using GT-POWER software was within 3.5%.

Framework for fault-tolerant speed tracking control of gasoline engines using the first principle-based engine model

Optimal engine torque management,a fundamental objective,depends predominantly on engine speed tracking performance.It ensures to attain desired speed profile in the presence of uncertainties,disturbances and malfunctions.On the other hand,certain requirements such as emissions control,fuel efficiency and drivability are degraded in case of poorspeed tracking.Furthermore,constraints on engine speed tracking performance are even more stringent for hybrid power-train architecture as crankshaft speed and engine torque are the basic variables for coordinated control.Speed tracking is also considered essential for gearshift control ofthe automatic transmission.In this research work,a framework for fault-tolerant speed tracking of the gasoline engine is proposed using the First Principle-based Engine Model(FPEM).A high-fidelity direct relationship between fuel injection input and engine speed is derived by the transformation of FPEM.Fault is induced in the fuel injection subsystem to generate the torque imbalance.Using the proposed framework,a second-order sliding mode-based control technique is applied to track desired speed profile by mitigating the faultsin the fuel injection subsystem.Reference data acquired from the engine test rig is used to demonstrate the offline validity and fault tolerance capabilities of the proposed framework in MATLAB/Simulink.