7/31/2019 Control of Exhaust Pollutants From Gasoline Engine

1/4

201O Itrtl Cfrc Cmptr Applct d Sstm CA 2010)

Control of Exhaust Pollutants from Gasoline Engine of Vehicle

Le XuSchool of Information &

Engineering, Changzhou Institute of TechnologyCZU

Changzhou, ChinaXulei@czu.cn

b- this paper, we rst introduce the exhaustpollutants from gasoline engine of vehicle's formation,harmfulness, and then show some technologies about itscontrol. We conclude that the combination use of fuelinjection's electronic control and the three-way catalystconverter is the most ecient method at present. This canmake the engine of vehicle t the normal emission standard.Now, the engine which uses alternative fuels, the mixed powerplant and the lean-burn engine are the focus of these days,perhaps they can provide a new way for resolving the gasolineengine's exhaust pollutants.

Kw vh; P; b; h

I. NTRODUCTION

In these days, about the 50% of the world's oil has beenconsumed in vehicle. The carbon dioxide release whichcomes om vehicles accounts for 30% of the wholetransporation's. Vehicles have been the biggest pollution

source, about 43% of air pollutants come om vehicles. Inbig city, we can get a higher percentage. There are almost700 billion vehicles in the whole world; the vehicles whichxed gasoline engine are far more than the vehicles whichxed diesel engine. And the gasoline engine's pollution isworse than the diesel engine's. How to control and decreasethe gasoline engine's exhaust pollutants eciently? This hasbeen the important question which answers the developmentdirection of vehicle. We will show our some research resultsabout gasoline engine's discharge and its control.

XAUST POLLUTANTS ROM GASOLIN

Gasoline is kind of compound hydrocarbon which

composed by a little of sulphur and plumbum. So thepollution is inevitable. the entire vehicle's exhaust gas, Naccounts or 72, CO accounts or O an wateraccount for 9.36% and the injurious ingredients account for1.64%. And in the injurious ingredients, CO accounts for85%, HC accounts for 5%, NO accounts for 8% and the restare the compound of sulphur and plumbum. Obviously, thevehicle's ehaust gas aect human's health greatly.[]

A The gasoline engine's greenhouse eect

Water and CO are all the products of normal combustion;they are nature matters of the physical world. But thegreenhouse effect which caused by these products are an

Xaoyan JangSchool of & Electric

Engineering, Changzhou Institute of TechnologyCZU

Changzhou, China

increasing conce. The eciency of energy sources' usecan be improved greatly by means of the ehaust pollutants'discharge control.[2]

B CO which comes from the gasoline's combustion

CO is a one of the products of combustion, and it is akind of product of incomplete combustion, it is an essentialproduct when the gasoline engine is working. CO is a kind ofharmful product. ability which combines withhaemoglobin is 300 times than O, nd it reduces the blood'scapacity of transporting O. Once the CO's density of airreaches 0.3%, people will be dying in several minutes. Onthe other hand, CO can be convered into CO; this canincrease the stream of chemical smoke's formation.

HC which comes from the gasoline's combustion

Usually there are three ways which produce HChydrocarbon. The rst which the gasoline's incompletecombustion accounts for 55% - 65%; the second which

comes om crankcase accounts for 20% - 25%; and the thirdwhich comes om the oil's evaporation accounts for -20%. Hydrocarbon is a kind of organic compound whosecomponents are very complicated; some of them can causecancer. The mixure of a certain density of HC and nitrogenoxide can cause photochemistry smoke that has lots of toxicingredients on the condition of strong sunshine. It's harmfulfor environments.

D N which comes from the gaoline's combustion

The conditions that there is plentil oxygen and hightemperature in engine are good for NO and NO products'formation. And NO accounts for 95%, NO accounts for 5%.They are not only toxic, but also the preconditions which

cause photochemistry smoke. Too much NO and NO maybea acd r. Th mot mrnt factor o cotrol r rel ratio, ratio of and ignition timing. [3]

E. Some particles which comes from the gasoline's

combustion

The gasoline engine's exhaust pollutants always havesome particles, they are mainly minimum lead compound,sulphate and some carbon smoke which caused by engine'simproper operation. Usually, these particles almost cause noimpact on the environment.

98/$ EEE 6

7/31/2019 Control of Exhaust Pollutants From Gasoline Engine

2/4

2010 Itrtl Cfrc Cmptr Applct d Sstm Mdl (ICCASM 2010)

I. TUDY ABOUT T XAUST POLLUTANTSDISCARG CONTROL O VICL GASOLIN NGIN

The harmlness of atmospheric pollution which caused

by vehicle exhaust was rst prompted by America in the pastcentury. Now, almost every country has established moreand more strict clauses about atmospheric pollution. Thepresent laws in America make the vehicle exhaust valuesabout CO, C and CO be reduced 96%, 98% and 90%separately than before. And in Japan, the exhaust has beenreduced 95%, 98% and 85% separately. In Europe, they arealso controlled strictly. All these laws have developed thecontrol technologies of gasoline engine's exhaust rapidly.[ 4]

A The principle of gasoline engine's electronic fuelinjection system for vehicle

Fig. shows the principle of gasoline engine's electronicel injection system for vehicle. With the development ofelectronic tecnology, especially for the large-scaleintegrated circuit's development, the injector location andinjection timing have been all improved. The injectionsystem has been developed om single point injection tomultipoint injection. Once all the cylinders injected at thesame time, now it has been change to sequential fueliection. So it is good for engine. The single-nctionalelectronic control fuel injection system has been developedinto the synthesized engine management system whichcontrols the oil mass, injection timing, ignition timing,ignition energy, air-fuel ratio, EGR and some auxiliary itemseciently. The improvement of electronic control systemcan get the el and air mixture instantaneously. This makes

the gasoline engine's emsson performance; powerperformance and fuel economy reach the best state.[5] Andthe present study of integrated power transmission must helpthe engine to operate efciently.

Hh TF

igure lectronic control el injection system of gasoline engine

B Comparing of vehicle gasoline engine's mechanicalinjection and electronic injection

Fig.2 shows the comparison of vehicle gasoline engine'smechanical injection and electronic injection. In the pastyears, almost every country has replaced the traditionalcarburetor with the advanced electronic fuel injection (EFI)system successively. In our country, the car which equippedwith carburetor had been banned about several years ago.

Comparing with the gasoline engine which equipped withcarburetor, electronic injection system can make the engine'spower be increased 5% - 10%, and the oil consumption isreduced 5% - 15%. All these improvements depend on theengine's exhaust control. e obvious advantages of EFIinclude that the precise control of oil mass, formation anddistribution of high quality fuel and air mixture. So thecombustion is well. On the other hand, the precise control ofoil mass is an antecedent of tree-way catalyst converer'secient operation.[6]

pu!sat ing . Hgh-rssr 1 Tub

pr6e TWAdvac Injetor

Fuel Injeto

Injection Pup Fl sly ppPulsin

Q yrate (3 / dcg)Fuel nection

ra (?/s)CaAgle

a) Mechic fuel iectonsystm of gasolin ngin

l in:

(b) Elcrni cnro flinjetion sysm

igure 2. Comparison between Mechanic el injection system engine andlectronic control el injection system

Ignition system of low exhaust vehicle

Ignition system is the most imporant part in gasolineengine. Both the characteristics of ignition timing andignition energy affect the combustion and the engine'sexhaust. Fig.3 shows the ignition advance angle map, andFig shows its error map. The popular and easy method ofexhaust control is ignition delaying. Although this canreduce the exhaust of C and CO obviously, it affects thepower and oil consumption. So, many factors should beconsidered synthetically in ignition timing. We cn acquirethe initial data by means of computer simulation, and thendraw the ignition advance angle map by the ignitioncalibration test. The ignition energy can be realized by meansof primary current's operate time. The operate time can beexpanded automatically when the battery voltage is lower

than the normal level, and the engine speed can be increasedb expaning the gle of attachment utomticll. Thegood operation of sparking plug is the basis of reliableignition.

J6

7/31/2019 Control of Exhaust Pollutants From Gasoline Engine

3/4

2010 Itrtl Cfrc Cmptr Applct d Sstm Mdl (ICCASM 2010)

-Q

.

0

.+b

'0

0

u0 4"r

b

i 35u

o

Rgsd mir;l

u u v I ssu!V

igure 3. Ignition advance angle

2

1

0

of opeaton

-O

igure 4. rror of ignition advance angle

D The optimization of ignition and air inlet system

The optimization of ignition and air inlet system hasmeaning to the control of exhaust. The compact combustionchamber causes the low thermal losses, and the completecombustion reduces the exhaust of HC and CO. Themeasures about reducing the slot between the piston and thecylinder wall can help the engine to reduce the exhaust. And

the optimized power performance and oil consumption arealso can be acquired by adjusting the ignition advance angle.Many foreign countries have realized multi-valve engine.Now, the four-valve and ve-valve technologies are

replacing the traditional two-valve and three-valvetechnologies. The engine's multi-valve structure hasimproved the engine's ventilation greatly. And the aerationeciency has been improved, too. It not only reduces thepumping loss, but also be convenient to place the sparkingplug in the central location.[7] The ventilating-fantechnology of Volkswagen Group also can get a pressureeect, and the oil consumption can be reduced. So theengine's power performance has been increased greatly, andthe exhaust of HC and CO also be reduced apparently. Onthe other hand, in order to make engine acquire the highestvolumetric efciency in all the range of rotation speeds,scientists are studying the intake-tube which can vary withthe engine speed.

ADI Group has applied the secondary vaatntechnology of intake-tube in vehicle engine. And the VTEC(variable valve timing and li electronic control system) alsohas been developed and applied; it can change the air massby changing valve timing and valve stroke automatically inaccordance with the engine speed and load. So the systemcan reduce the oil consumption and exhaust of N on thebasis of improving the engine's performance.

E. Three-way catalyst converter

Thee-way catalyst converer is the most effectivemethod which used to control exhaust. Three-way catalystconverer not only promotes oxidation reaction of CO andHC, but also promotes their oxidation-reduction reaction. So,all the toxic ingredients can be puried. The experimentshave shown that the exhaust of HC and CO can be reduced90% - 95% by means of air-el ratio closed-loop control and

three-way catalyst converer. The core of three-way catalystconverer is catalyst carrier which covered by activesubstance. Most of the catalyst carriers are cellular porouscordierite ceramics, aluminum oxide porous pelletedsubstrate which produced by Japan has been fallen intodisuse. Usually, the active substance includes some noblemetal, such as Pt, Pb and . The catalytic effect can also beimproved by adding some rare earh element in catalyst.Whether the three-way catalyst converer gets high ecientoperation depends on air-el ratio, and it must be limited ina small range. This can be well done by the closed-loopcontrol which executed by EMS. The catalyst's normaloperation temperature is 350 'C, some EMS which equippedwith auxiliary TWC heating device can reach the

temperature rapidly. On the other hand, the oil supply mustbe cut o if existed misring or reverse towing. Otherwise,the plenty of unbued el cause thermal aging. Someimpurities and additives which are in the fuel decrease thecatalyst's eciency. And all the elements of P, Mn, S, Siand Pb can cause catalyst poisoning. So, we must payattention to use all kinds of catalysts.

Exhaust gas recirculation system (EGR)

Reducing the gasoline engine's exhaust is the mainfunction of EGR. Because the density of oxygen in exhaustgas is very low, and the specic heat capacity of exhaust gasis high, so the introduced ehaust gas may be used to reduce

the highest temperature of combustion properly, and blockthe formation of N But the introduced exhaust gas alsoaects the combuston, the highest power of engine will bedecreased, the oil consumption will be added and thereliability of combustion will be decreased. The keytechnology of EGR is controlling the exhaust gas quantity.Usually, EGR increases with load. But in order to getsucient power, EGR will be disabling when the load is llor low. On the other hand, in order to realize the optimumeciency, EGR will also be disable when the engineoperates waly, idly and idling. Exhaust gas must bedistributed in every cylinder uniformly.

66

7/31/2019 Control of Exhaust Pollutants From Gasoline Engine

4/4

2010 Itrtl Cfrc Cmptr Applct d Sstm (ICCA 2010)

G. Positive Crankcase Ventilation system C

Now, PCV system must be accepted in gasoline engine.Seal gas system which consists of piston, piston ring and

cylinder is labyrinth seal-rotating system essentially, and theblow-by of engine is inevitable. The quantity of blow-byequal the cylinder's total air discharging capacity's 0.5% -1.0%. The blow-by consists of plentil unbued substance,some harml gas HC and CO. necessary to putcrankcase's exhaust into air inlet manifold, so the exhaustcan be bu out in cylinder. On the other hand, canprotect engine when it backs re.

Fuel evaporative emission control system

The el always is exposed in thermal radiation, and onthe occasion of multipoint injection, the retu el whichcome om el spray nozzle ow into the el tank with a lotof heat. So the el tank will produce some el evaporationbecause the rising temperature. On this occasion, the quantityof will exceed the total exhaust 20% without anycontrolling. here the control about exhaust isaccomplished by evaporative emission control system. Andthe system consists of purge valve and some pipelines. Aerthe el evaporation being cleaned by means of purge valve,the exhaust will be sent to air inlet manifold. The elevaporation may be handled by the system properly.

IV. COMPUTERAIDED DIAGNOSIS SYSTEMS WITAUTOMOBILE

computer-aided diaosis system withautomobile has been the development priority of exhaust

control recently. Many researches show that the exhaust isclosely bound up with vehicle failures. Usually, there isabout 70% vehicle exhaust caused by 20% poor performanceengines. So the engine's performance is very imporant to theexhaust's control. Computer-aided diagnosis system withautomobile simplied the complicated diagnosis andmaintenance of initially. Now, the second-generationcomputer-aided diagnosis system with automobile hascentralized in the control of exhaust. OB-II computer-aideddiagnosis system with automobile surveys the conceeddevices and systems, and shows the failure by means ofindicator lamp when any imporant failure happened or thethree-way catalyst converer's exhaust exceeds the 1.5 timesFTP value. And the failure code and the engine's operating

data will be saved. Then the system stars the backupdatabase and the engine will be gotten corrected OB-IImainly surveys the following nine functions: the eciencyof three-way catalyst converer, misring, fuel system,lambda sensor, system, synthetic devices, evaporativeemission control system, secondary air injection system anduorocarbon. These surveys are all conceed with engine's

operation. So, it's necessary to survey all kinds of factorswhich can aect the vehicle exhaust.

V. HYBRID SYSTEMSThe study of hybrid system provides a new way to

resolve the vehicle exhaust. The experiments show that thegasoline engine may be worked in high theal eciencyand low exhaust. This is good for the optimization of exhaustprocess system. Lots of foreign countries have proucedmany kinds of hybrid vehicles; its engines provide powerunder the ideal situations. And on the other situations, thevehicles were powered by other motor system. This canreduce the fuel consumption and the exhaust of CO. The keytechnology of hybrid system is how to make sure the systemoperation mode and control strategy. That means whichoperation mode to choose and how to optimize and controlthe engine under the mode.

VI. ONCLUSIONS

There are many factors about gasoline engine's exhaust,and some factors may be contradicted each other. theprocess of vehicle exhaust control, we must consider all thefactors synthetically. And we also consider the engine'spower and ecient, we should accept the correspondingsynthetic control measures in accordance with the particularcase. Now the most ecient design is combining the threeway catalyst converer with the engine management systemwhich uses closed-loop fuel injection control, and it's goodto control the exhaust of HC and CO. The study about theprocess's optimization of air in-let and combustion is under

way. The study about gasoline engine's exhaust is theimportant mission for us.

[] Nakajima,Yamaguchi and Tashiro "Study of TWC in AbsorberCatalyst System for Gasline Direct Injection Engine SAE2001-01-1300.

[2] Lake T..ct al Expeniene of a Muticylinder CCVSEngineSAE950165,1995.

[3] Liu Zhiqiang, Wu Wenbing, Some technologies about reducinggasoline engine's exhaust[J], Middle South AutomotiveTransportation, 2003(0).

[4] Chen Yan, Yan Wei, Control of vehicle gasoline engine's exhaust[J],Shandong Gas Engine, 2009(9).

[5] Liu Xunjun, Gas Engine's Exhaust and Control[M], Beijing ChinaMachine Press, 2003

[6 Wang Suishuang, Li Jianwen, Lan ongguo, Principe and repair ofvehicle electronic control system[M], Beijing: Institute ofTechnology Press, 1999.

[7] Liu Shuliang, Xu zhengzhong, Effect of In-cylinder Tumbling AirFlow on Engine Performance in S.I.Engines[J], TRANSACTIONSOF CSICE, 2005(3) 23-27.

67