Technology To Meet New Emission Norms

Presentation on “ Technologies to meet Bharat Stage III and IV emission legislations on Automotive Vehicles ”

Preet Ferozepuria

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Contents 1. Introduction to Automotive Emission 2.Emission Norms: BS III & IV (Passenger Car and Commercial vehicles) 3.Technology Available 2.1

Commercials Vehicles for BS III 2.1.1 2.1.2 2.1.3 2.1.4

2.2

Commercial Vehicles for BS IV 2.2.1 2.2.2

3.

Rotary pumps Diesel Oxycat (DOC) Turbochargers EGR Common rail EGR

Passenger Vehicles 3.1

Diesel 3.1.1 3.1.2 3.1.3 3.1.4

3.2

Advantages of Diesel Passenger vehicles Available technologies for BS III norms Technologies for BS IV norms Technologies for BS V norms

Gasoline

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Thermochemistry of fuel-air mixture PRINCIPLE CONSTITUENTS OF DRY AIR Gas

ppm by Volume

Molecular Weight

Mole Fraction

Molar Ratio

O2 N2 Ar CO2 Air

2,09,500 7,80,900 9,300 300 10,00,000

31.998 28.012 38.948 40.009 28.962

0.2095 0.7905

1 3.773

1

4.773

• O2 is the reactive component in air. • Air (O2 -21% and N2 -79%) • For 1 mole of O2 there is 3.773 moles of N2 Preet Ferozepuria

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I.C. Engine Fuels Gasoline or Petrol

Diesel

CNG

LPG

Biofuels Ehanol Alcoholes

Petrol and diesel are blend of different hydrocarbon refining crude oil Petrol: General formula : CnH1.87n C8.26H15.5 C7.76H13.1 to LHVP = 44, 000 KJ/Kg, mol. wt. ≅ 110

compounds obtained by

Diesel: General formula : CnH1.8n C10.8H18.7 LHVP = 42500 KJ/Kg, mol. wt. ≅ 148.6 S’ up to 1%, Preet Ferozepuria 4

CNG (Compressed Natural Gas) – Mainly Methane. RON is higher, therefore, can run at higher C.R. as compared to Gasoline. Thus, more efficient engine. LPG (Liquefied Petroleum Gas) – Mixture of Propane and Butane. Note: Butane content is higher in domestic LPG, which can cause gumming inside the engine, thus not recommended for Automotive purpose. E10 Fuel: With 10% ethyl alcohol derived from sugarcane added in gasoline.

B10 Fuel: With 10% diesel supplements, for example, ‘Jatropha’ oil being added into diesel. The fuel injection manufacturers like BOSCH allow up to 10% blending to safeguard against warranty of Fuel Injection components.

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Combustion Stoichiometry Complete combustion (Oxidation) when sufficient oxygen is available. The carbon in the fuel is converted to CO2 and Hydrogen to H2O. C3H8(propane) + 5O2 = 3CO2 + 4H2O Complete combustion (oxidation) of general hydrocarbons in air at low temperature, when N2 is non reactive: CaHb + (a+b/4)(O2+3.773N2)=aCO2 +b/2H2O+3.773(a+b/4) N2 Above equation defines, Stoichiometric or chemically correct or theoretical proportion of fuel and air; i.e. there is just enough oxygen for conversion of all the fuel into completely oxidized products. (Stoichiometric combustion occur when all the oxygen is consumed in the reaction & there is no molecular oxygen(O2) in the product)

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The stoichiometric air/fuel ratio depends upon fuel composition. (A/F)s = (1+y/4)(32+3.773 x 28.16) = 34.56(y+4) 12.011+1.008y 12.011+1.008y When y=b/a for fuel composition written as CHy where molecular weight of O2,atmospheric N2, atomic carbon and atomic hydrogen are respectively ,32, 28.16,12.011 and 1.008 (A/F)s depends on y only i.e. (A/F)s diesel = 34.56(1.73 + 4) = 198.03 = 14.4 12.011 + 1.008 x 1.73 13.75 (A/F)s petrol = 14.5  For gasoline/diesel as fuel, as it is a mixture of hydrocarbons a & b are not integers.

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For diesel taking C10.8H18.7 as average donation , molecular weight will be; Mdiesel = 12.011a + 1.008b = 12.011 x 10.8 + 1.008 X 18.7 = 148.6  For octane C8H18, at (A/F)s = 34.56(4+2.25) = 216 =15.13 12.011+1.008 x 2.25 14.279 the complete combustion is as per below equation (FUEL) + (AIR) = (PRODUCTS) C8H18 + 12.5 (O2 + 3.773 N2) = 8CO2+9H2O + 47.16N2 At 25% excess air then the stoichiometric or fuel-lean combustion, the extra air appears in the product in unchanged form. C8H18 + 1.25 x12.5(O2 + 3.773N2) = 8CO2 + 9H2O + 58.95N2 + 3.13O2 With less than the stoichiometric air requirement, i.e., with fuel-rich combustion, there would be insufficient oxygen to oxidize fully C and H to CO2 & 3H2O with CO appearing in the products.

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The ratio of actual A/F ratio to stiochiometric A/F ratio is important parameter for defining mixture composition. λ = (A/F)actual/ (A/F)s For lean mixture: λ> 1 For Rich mixture: λ< 1 For stiochiometric mixture: λ= 1 For SI engines 0.8 < λ < 1.2; For diesel engines 1.3 < λ < 5.0 In SI engine, the air mass flow rate is being changed through a venturi while maintaining λ in close range. This results into very high pumping losses under part load causing poor overall efficiency. The diesel engine runs at about same air flow rate while fuel quantity is being varied form 1.3 : 5. Therefore, pumping losses are small and diesel engine runs more efficiently on lean mixture. Therefore, CO produced is significantly less as compared to an SI engine.

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For

alcohols, the fuel oxygen is included in the oxygen balance between reactants and products. For ethyl alcohol(ethanol) C2H5OH, the stoichiometric combustion equation is: C2H5OH + 3(O2+3.773N2) = 2CO2 + 3H2O +11.32 N2 (A/F)s= 9.00 NOTE: At normal combustion temperature significant dissociation of CO2 and H2O occurs & NO and NO2 is generated.

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BENEFITS OF DIESEL FUEL ENGINES 1. Fuel-efficient by 30 % 3.00

2.5 B-Segement cars Diesel -IDI 15% further advantage by DI

Cost of Running / km(Rs/Km)

2.50 2.00

1.5

1.50 1.00 0.50 0.00

Petrol

Diesel

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2. Subsidy by Government on Diesel Fuel • Diesel prices less by 30% in India • Diesel prices 16% less in Europe

Petrol ~ 40.5 Rs/Lts

Diesel ~ 30.0 Rs/Lts

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3. Less CO2 emission By 2008, new vehicles legislated to meet limit of 140g/km in Europe.

Engine R.P.M 2000, Both Engines Euro II compliant

% CO2 EMISSION COMPARISION CNG V/S DIESEL ENGINE

14 12 11

11.3

11.1

11.6

10 8

7.4 6.3

6

5 4

3.6

CNG Engine Diesel Engine

2 0

25

50

75

100

LOAD

The CO2, which is a greenhouse effect gas, emitted far less by diesel engine as compared to Petrol and CNG engines equipped with TWCs (Three Way Catalysts). Preet Ferozepuria

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CO2 Reduction Roadmap for Passenger cars

165 165 g/km

-1%

Vehicle Weight

-3%

Reduce losses (Aerodynamic, lubricants, rolling resistance, powertrain friction)

-2%

Diesel Penetration by 50%

-0.7%

Gasoline DI Penetration by 7%

150

-1.3%

‘VVA’ penetration by 15%

145

-3.5%

5-10% ENGINE DOWNSIZING

-2%

CVT & DCT penetration by 25%

-1%

Mild Hybrid penetration by 5%

160

Reduction by 2%

155

140

140 g/km

2001

2008

Further CO2 Reduction: -20% by 2012 -30% by 2016

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Actual Combustion Products At normal combustion temperature and reaction rates, significant dissociation of CO2 occurs to generate CO; NO and NO2 is generated form Atmospheric N2.

(Cn Hp+S) + O2

CO2 + H2O

+

DIESEL FUEL

NOX

HC

CO

PM

+ SO2 +SO3

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DIESEL ENGINE EMISSION

GASEOUS POLLUTANTS VISIBLE POLLUTANT --SMOKE

PM

NOX

HC

CO

CO2

LEGISLATED

TO BE LEGISLATED

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EMISSION NORMS: BS III & IV

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BHARAT STAGE-III EMISSION NORMS FOR PASSENGER VEHICLES (Cars & SUVs/MUVs) DIESEL ENGINE Category by Reference Mass (RW), kg

CO (g/km)

HC+NOx (g/km)

NOx (g/km)

PM (g/km)

(Up to 6 occupants) or RW≤1305 kg RW between 1305-1760 kg

0.64

0.56

0.50

0.05

0.80

0.72

0.65

0.07

RW >1760 kg

0.95

0.86

0.78

0.10

Reference Mass of vehicle: Kerb Weight + 150 kg

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BHARAT STAGE-IV EMISSION NORMS FOR PASSENGER VEHICLES (Cars & SUVs/MUVs) DIESEL ENGINE Category by Reference Mass (RW), kg

CO (g/km)

HC+NOx (g/km)

NOx (g/km)

PM (g/km)

(Up to 6 occupants) or RW≤1305 kg RW between 1305-1760 kg

0.50

0.30

0.25

0.025

0.63

0.39

0.33

0.04

RW >1760 kg

0.74

0.46

0.39

0.06

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BHARAT STAGE-III EMISSION NORMS FOR PASSENGER VEHICLES (Cars & SUVs/MUVs) GASOLINE ENGINE Category by Reference Mass (RW), kg

CO (g/km)

HC (g/km)

NOx (g/km)

(Up to 6 occupants) or RW≤1305 kg

2.3

0.20

0.15

RW between 1305-1760 kg

4.17

0.25

0.18

RW >1760 kg

5.22

0.29

0.21

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BHARAT STAGE-IV EMISSION NORMS FOR PASSENGER VEHICLES (Cars & SUVs/MUVs) GASOLINE ENGINE Category by Reference Mass (RW), kg

CO (g/km)

HC (g/km)

NOx (g/km)

(Up to 6 occupants) or RW≤1305 kg

1.0

0.1

0.08

RW between 1305-1760 kg

1.81

0.13

0.10

RW >1760 kg

2.27

0.16

0.11

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Deterioration Factor 

Deterioration factor (DF) as given in below Table is the margin, which is applied on emission norm values so that over the life of vehicle emission is not exceeded. Engine Catego ry

Deterioration Factor CO

HC

NOx

Gasoline 1.2 Engines

1.2

1.2

HC+NO x

PM

Not Applicable

Diesel 1.1 N.A. 1.0 1.0 1.2 Engines Alternatively, the vehicle manufacturer may opt for an ageing test of 80, 000 km for evaluating deterioration factor.

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TECHNOLOGY AVAILABLE COMMERCIALS VEHICLES FOR BS III

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MECHANICALLY-CONTROLLED DISTRIBUTOR PUMPS (VE) 1 2 3 4

5 6 7 8 9

Fuel tank Fuel filter, Distributor fuelinjection pump, Nozzle holder with nozzle, Fuel return line, Sheathed-element glow plug (GSK) Battery, Glow-plug and starter switch, Glow control unit (GZS).

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FUEL-INJECTION TECHNIQUES Fields of application •

Small high-speed diesel engines demand a lightweight and compact fuel-injection installation. The VE distributor fuelinjection pump fulfills these stipulations by combining – – – –

Fuel-supply pump, High-pressure pump, Governor, and Timing device,

Fig.: VE distributor pump fitted to a 4-cylinder diesel engine

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The subassemblies and their functions 1

2

3

4 5

Vane-type fuel-supply pump with pressure regulating valve: Draws in fuel and generates pressure inside the pump. High-pressure pump with distributor: Generates injection pressure, delivers and distributes fuel. Mechanical (flyweight) governor: Controls the pump speed and varies the delivery quantity within the control range. Electromagnetic fuel shutoff valve: Interrupts the fuel supply. Timing device: Adjusts the start of delivery (port closing) as a function of the pump speed and in part as a function of the load.

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Design and construction 1 2 3 4

Pressure-control valve, Governor assembly, Overflow restriction, Distributor head with highpressure pump, 5 Vane-type fuel-supply pump, 6 Timing device, 7 Cam plate, 8 Electromagnetic shutoff valve.

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Fuel supply and delivery

Low-pressure delivery It delivers a virtually constant flow of fuel per revolution to the interior of the injection pump. • Using this valve, it is possible to set a defined pressure for a given speed. Components •

1 Drive shaft, 2 Pressure-control valve, 3 Eccentric ring, 4 Support ring, 5 Governor drive, 6 Drive-shaft dogs, 7 Overflow restriction, 8 Pump housing.

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Low-pressure delivery Fuel tank Requirements: • The fuel tank must be of non-corroding material, and must remain free of leaks at double the operating pressure at 0.3 bar. • Suitable openings or safety valves must be provided, • Fuel must not leak past the filler cap or through pressure compensation devices. • The fuel tank and the engine must be so far apart from each other that in case of an accident there is no danger of fire.

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Low-pressure delivery Fuel lines Requirements: • An alternative to steel pipes, flame-inhibiting, steel-braid-armored flexible fuel lines can be used for the low-pressure stage • These must be routed to ensure that they cannot be damaged mechanically, and • They cannot be damaged fuel which has dripped or evaporated must not be able to accumulate nor must it be able to ignite.

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Low-pressure delivery Fuel Filter The injection pump’s high-pressure stage and the injection nozzle are manufactured with accuracies of several thousandths of a millimeter. • Fuel filter specifically aligned to the requirements of the fuel-injection system is absolutely imperative if trouble-free operation and a long service life are to be achieved. •

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Low-pressure delivery Vane-type fuel supply pump The vane-type pump is located around the injection pump’s driveshaft. • Its impeller is concentric with the shaft and connected to it with a Woodruff key and runs inside an eccentric ring mounted in the pump housing. •

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Low-pressure delivery Pressure-control valve The pressure-control valve is connected through a passage to the upper (outlet) kidney-shaped recess, and is mounted in the immediate vicinity of the fuelsupply pump. • If fuel pressure increases beyond a given value, the valve spool opens the return passage so that the fuel can flow back to the supply pump’s suction side. •

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Low-pressure delivery Overflow restriction The overflow restriction is screwed into the injection pump’s governor cover and connected to the Pump’s interior. • It permits a variable amount of fuel to return to the fuel tank through a narrow passage •

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High-pressure delivery Delivery valve The delivery valve closes off the high-pressure line from the pump. • It has the job of relieving the pressure in the line by removing a defined volume of fuel upon completion of the delivery phase • The delivery valve is a plunger-type valve. It is opened by the injection pres-sure and closed by its return spring. •

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High-pressure delivery Constant-pressure Valve with return-flow restriction (RSD) To prevent such harmful reflections, the delivery valve is provided with a restriction bore which is only effective in the direction of return flow. • This return-flow restriction comprises a valve plate and a pressure spring so arranged that the restriction is ineffective in the delivery direction, whereas in the return direction damping comes into effect. •

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High-pressure delivery Constant-pressure valve (GDV) •

constant-pressure valves are fitted which relieve the high-pressure system (injection line and nozzle and holder assembly) by means of a single-acting non-return valve which can be set to a given pressure,(e.g., 60 bar).

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Fuel supply and delivery High-pressure stage The fuel pressure needed for fuel injection is generated in the injection Pump’s high-pressure stage. • The pressurized fuel then travels to the injection nozzles through the delivery valves and the fuel-injection tubing. •

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High-pressure stage Distributor-plunger drive The distributor plunger is held in the cam plate by its cylindrical fitting piece and is locked into position relative to the cam plate by a pin. • The distributor plunger is forced upwards to its TDC position by the cams on the cam plate, and the two symmetrically arranged plunger-return springs force it back down again to its BDC position. •

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High-pressure stage Cam plates and cam contours The cam plate and its cam contour influence the fuel-injection pressure and the injection duration, whereby cam stroke and plunger-lift velocity are the decisive criteria. • the different combustion-chamber configurations and combustion systems used in the various engine types, the fuel-injection factors are individually tailored to each other. •

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High-pressure stage Distributor head Generates the high pressure and distributes the fuel to the respective fuel injector. 1 Yoke, 2 Roller ring, 3 Cam plate, 4 Distributor-plunger foot, 5 Distributor plunger, 6 Link element, 7 Control collar, 8 Distributor-head flange, 9 Delivery-valve holder, 10 Plunger-return spring, 4 8 Distributor head.

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High-pressure stage Fuel metering The fuel delivery from a fuel-injection pump is a dynamic process comprising several stroke phases • The cam plate rotates against the roller ring, whereby its cam track follows the rollers causing it to lift (for TDC) and drop back again (for BDC) •

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High-pressure stage Distributor plunger with stroke and delivery phases

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MANIFOLD – PRESSURE COMPENSATOR (LDA) - A turbocharger forces pressurized fresher air into the intake tract. This charge –air pressure allows a diesel engine of any given displacement to generate more power and torque than its atmospheric – induction counterpart in any given speed band. - Fuel delivery by the pump is adapted to suit the increase density of this air charge to get effective Power increase. - During part load operation when cylinder charge density is relatively low, fuel delivery is reduced so as not to result into higher visible smoke. This function is carried out by Manifold – Pressure Compensator (LDA), which is mounted on top of a distributor pump (also possible on inline pump).

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MANIFOLD – PRESSURE COMPENSATOR (LDA) Design and construction The interior of the LDA is divided into two separate airtight chambers by a diaphragm to which pressure is applied by a spring. • The diaphragm is connected to the LDA’s sliding pin which has a taper in the form of a control cone. •

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MANIFOLD – PRESSURE COMPENSATOR (LDA) Method of operation •

In the lower engine-speed range charge-air pressure generated by exhaust turbocharger and applied to diaphragm is insufficient to overcome pressure of the spring.

•

As soon as the charge-air pressure applied to the diaphragm becomes effective, the diaphragm, and with it the sliding pin and control cone, shift against the force of the spring. Should the turbocharger fail, the LDA reverts to its initial position and the engine operates normally without developing smoke

•

the the the the

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LFB- LOAD DEPENDENT TIMING ADVANCE FUNCTION - As the diesel engine’s load factor changes , the start of injection must be advanced or retarded accordingly. - The load – sensitive start of delivery is designed to react to declining loads (from full – load to part throttle) by retarding start of delivery and responds to rising load factors by shifting the start of delivery towards advancing. This adaptive process provides smoother engine operation along with cleaner emissions at part throttle and idle. NOTE: The LFB can be deactivated to reduce HC emissions generated by the diesel engine when it is cold (<60˚c).

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LFB- LOAD DEPENDENT TIMING ADVANCE Design and construction •

•

For load-dependent injection timing, modifications must be made to the governor shaft, sliding sleeve, and pump devices housing. The sliding sleeve is provided with an additional cutoff port, and the governor shaft with a ringshaped groove, a longitudinal passage and two transverse passages .

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LFB- LOAD DEPENDENT TIMING ADVANCE Method of operation As a result of the rise in the supply-pump pressure when the engine speed increases, the timing device adjusts the start of delivery in the advance direction. • The control lever is used to input a given full-load Speed. •

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KSB- Cold Start injection Advance - The cold – start compensation device improves the diesel engine’s cold – start response by advancing the start of delivery. - This feature is controlled by an automatic temperature – sensitive control device which take input from coolant and / or ambient temperature.

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KSB- Cold Start injection Advance Design and construction The KSB is attached to the pump housing, the stop lever being connected through a shaft to the inner lever on which a ball pin is eccentrically mounted. • The automatic advance mechanism is mounted on the distributor pump, whereas the manual operating mechanism is in the driver’s cab. •

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KSB- Cold Start injection Advance Method of operation Automatically and manually operated cold-start accelerators (KSB) differ only with regard to their external advance mechanisms. • KSB is triggered by the driver from the cab (timing-device KSB), independent of the advance defined by the timing device (a), an advance of approx. 2.5 camshaft is maintained (b) •

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ATMOSPHERIC – PRESSURE SENSITIVE FULL LOAD STOP (ADA) - Owing to the lower air density , the mass of inducted air decreases at high altitudes. - If the standard fuel quantity prescribed for full – load operation is injected , there will not be enough air to support full combustion. The immediate results are smoke generation and rising engine temperatures . - The atmospheric pressure –sensitive full – load stop can help prevent this condition. -

It varies full – load fuel delivery in response to changes in barometric pressure .

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ATMOSPHERIC – PRESSURE SENSITIVE FULL LOAD STOP (ADA) Design and construction •

The construction of the ADA is identical to that of the LDA. The only difference being that the ADA is equipped with an aneroid capsule which is connected to a vacuum system somewhere in the vehicle (e.g., the power-assisted brake system). The aneroid provides a constant reference pressure of 700mbar (absolute).

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ATMOSPHERIC – PRESSURE SENSITIVE FULL LOAD STOP (ADA) Method of operation Atmospheric pressure is applied to the upper side of the ADA diaphragm. The a reference pressure (held constant by the aneroid capsule) is applied to the diaphragm’s underside. • If the atmospheric pressure drops (for instance when the vehicle is driven in the mountains), the sliding bolt shifts vertically away from the lower stop and, similar to the LDA, the reverse lever causes the injected fuel quantity to be reduced. •

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SOLENOID-VALVE-CONTROLLED AXIAL-PISTON DISTRIBUTOR FUEL-INJECTION PUMPS (VE-MV) This pump is of modular design. The field- proven distributor injection pump can thus be combined with a new electronically controlled fuelmetering system. • The most important new components are: •

1. Angle-of-rotation sensor which is located in the injection pump on the driveshaft between the vane-type supply pump and the roller ring, 2. Electronic pump ECU, which is mounted as a compact unit on the top side of the pump and connected to the engine ECU, 3. High-pressure solenoid valve, installed in the center of the distributor head.

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METHOD OF OPERATION

The distributor head and the opened high-pressure solenoid valve, the vane-type supply pump delivers fuel to the high-pressure chamber at a pressure of approx. 12 bar. • No fuel is delivered when the highpressure solenoid valve is deenergized (open). • The valve’s instant of closing defines the injection pump’s start of delivery. • Similarly, the valve’s instant of opening defines the pump‘s end of delivery. •

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DIESEL OXIDATION CATALYSTS (DOC) •

Flow through oxidation catalyst (two-way catalytic convertor) for reduction of CO and VOF (80%), and PM SOF (20-30%). Does not retain PM.

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BASICS OF TURBOCHARGERS • To increase performance increase the inlet density. – Done by manifold tuning or forced induction.

• Pack more air into cylinders. • Typical boost of 6 to 8 psi provided. • Significantly raise horsepower without significant weight gain. Preet Ferozepuria

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WHY IT IS EFFECTIVE 

Through the use of forced induction, turbochargers compress the air entering the engine causing it to be extremely dense; with more air in a small area, more gasoline can be coupled with the air creating larger explosions in the cylinder which help the car to progress forward

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Turbocharger Design Process of the air flow:

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BENEFITS OF TC ON ENGINE PERFORMANCE

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BENEFITS OF TC ON ENGINE PERFORMANCE More specific power over naturally aspirated engine. This means a turbocharged engine can achieve more power from same engine volume. • Better thermal efficiency over both naturally aspirated and supercharged engine when under full load (i.e. on boost). This is because the excess exhaust heat and pressure, which would normally be wasted, contributes some of the work required to compress the air. • Weight/Packaging. Smaller and lighter than alternative forced induction systems and may be more easily fitted in an engine bay. • Fuel Economy. Although adding a turbocharger itself does not save fuel, it will allow a vehicle to use a smaller engine while achieving power levels of a much larger engine, while attaining near normal fuel economy while off boost/cruising. This is because without boost, less fuel is used to create a proper air/fuel ratio. •

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Problems of Altitude • • •

Air density and pressure decrease 1/2 as much air at 20,000 feet as at sea level Less oxygen NOTE: Temperature and exhaust back pressure are decreasing but this is not enough to offset the decline in density and pressure

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How Turbocharger helps •

•

•

•

•

More fuel and air at a higher pressure can produce more horsepower within an engine A naturally aspirated engine can only burn as much fuel as it has air to mix with Mechanical aspiration increases the density of the air in the induction manifold so that more fuel can be added Mechanical aspiration increases the pressure in the combustion chamber to increase power The increases in power are limited by the strength, temperature, and lubrication limits in the engine Preet Ferozepuria

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DETAILING SPECIFIC PARTS      

Turbine Compressor Intercooler Tachometer and Boost Gauge Wastegate Bearings

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TURBINE •

• • • •

•

The exhaust flow from the engine is directed over the blades of the turbine to provide the force to turn the shaft and compressor Leaks in the exhaust system before the turbine will decrease performance Combustion deposits may form on the turbine and reduce efficiency Turbine speed is controlled to change the amount of boost available Proper mounting and connection between the turbine and turbine shaft is necessary because it operates at such high speeds. The Wastegate releases excess exhaust waste from the turbine.

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Turbine Technology Main Parts Turbine rotor 2. Turbine nozzle Ring 3. Turbine casing 1.

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1.Turbine Rotor Blades are forged of Nimoinic alloy  It is connected with rotor shaft by means of friction welding.  Blades are fastened to turbine disk by means of fir-tree foot connection. 

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2. Turbine nozzle Ring Nozzle Ring casing is insulated with simple and high efficient material to reduce the temperature and Noise.  With improved flow in nozzle ring, Reduce the Vibration acceleration of rotor blade and improved stability of nozzle ring. 

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3. Turbine Casing A turbine casing for enclosing a gas turbine component, such as a fan, a compressor, a combustion chamber or a turbine. • The suction-side opening forms an outlet-flow opening for the medium • The pressure-side opening forms an inlet-flow opening. • Applications of the turbine casing are particularly suitable both for highpressure turbines and for mediumpressure turbines •

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COMPRESSOR • When the compressor wheel spins, it draws in air from the ambient air inlet located on the opposite side of the turbine exhaust gas inlet to retrieve cool air. • The compressor increases the density of incoming air by six to eight pounds per square inch (psi). • At sea level, the density of air is 14.7 psi, so the compressor yields about a fifty percent increase (Nice). • The highly compressed air leaves the compressor section through the compressor air discharge as it travels towards the intercooler.

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Compressor Technology Main parts: 1. 2. 3. 4.

Compressor wheel (inducer & impeller) Compressor silencer-air filter Air intake casing Compressor outlet casing

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Compressor wheel (inducer & impeller)

•

It is made up of a single piece high-strength aluminum alloy and titanium for compression ratio 4.5 and to withstand up to 560 m/s circumferential velocity.

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Compressor silencer-air filter

•

Air intake silencer housings can be useful for silencing objectionable air intake noise and providing protection for air compressors.

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An intake silencer for attenuating intake air noise, and being disposed to fluidly connect said air filter box with an air intake port of said compressor .

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Air intake casing

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It is either constructed with 90 degree bent or as an axial air inlet duct

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The larger flow paths and widecurved deflection regions exhibits constant pressure and velocity distribution at compressor inlet.

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Compressor outlet casing

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Having wide flow sections and large outlet areas.

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It convert kinetic energy into pressure energy. Note: In large propulsion engine (Charge above 4.0 bars), Compressor casing can be heat insulated

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TRIM •

Trim is a term to express the relationship between the inducer and exducer of both turbine and compressor wheels.

•The inducer diameter is defined as the diameter where the air enters the wheel, •whereas the exducer diameter is defined as the diameter where the air exits the wheel.

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A/R(Area/Radius) Ratio •

It is defined as the inlet (or, for compressor housings, the discharge) cross-sectional area divided by the radius from the turbo centerline to the centroid of that area

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Compressor A/R  Larger A/R housings are used for low boost applications.  Smaller A/R are used for high boost applications.

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Turbine A/R  Smaller A/R will increase the exhaust gas velocity into the turbine wheel  Larger A/R will decrease the exhaust gas velocity into the turbine wheel

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VARIABLE GEOMETRY TURBOCHARGER (VGT) A Variable Geometry turbocharger is also known as a variable Turbine geometry turbocharger (VTGT), or a Variable Nozzle Turbine (VNT). • usually designed to allow the effective aspect ratio(sometimes called A/R Ratio) of the turbo to be altered as conditions change. • The vanes are controlled by a membrane actuator identical to that of a Wastegate, although electric servo actuated vanes are becoming more common. •

WHY : Big turbocharger do not work well at slow engine speeds, while small turbocharger are fast to spool but run out of steam pretty quick. But VTG turbocharger solve this problem

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VARIABLE GEOMETRY TURBOCHARGER WORKING A turbocharger equipped with Variable Turbine Geometry has little movable vanes which can direct exhaust flow onto the turbine blades. The vane angles are adjusted via an actuator. The angle of the vanes vary throughout the engine RPM range to optimize turbine behavior. In this cut-through diagram, The direction of exhaust flow when the variable vanes are in an almost closed angle. The narrow passage of which the exhaust gas has to flow through accelerates the exhaust gas towards the turbine blades, making them spin faster. This cut-through diagram shows the exhaust gas flow when the variable turbine vanes are fully open. The high exhaust flow at high engine speeds are fully directed onto the turbine blades by the variable vanes. Preet Ferozepuria

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EGR (EXHAUST GAS RE-CIRCULATION) Concept : exhaust –gas recirculation (EGR) is highly effective measure for NOx emissions on diesel engines.

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EGR IS EFFECTIVE MAINLY DUE TO : - Reduction in fresh intake air mass going into cylinder as it is replaced with inert exhaust gases. -This results in drop in rate of combustion and thus leads into reduction of peak temperature. Reduction in local excess – air factor. - At part load with higher EGR rates, almost homogeneous mixture conditions are achieved resulting into extremely low – NOx and low – particulate combustion.

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WORKING OF EGR

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ON/OFF EGR USING VALVE : -Solenoid operated on/off EGR value -Value put on intake side for longer life -On/off status to be decided by -Position of accelerator lever of fuel injection pump -Usually valve is switched at 80 -90 % of full travel of accelerator

-A micro – switch or a throttle position sensor (TPS) used to signal On/ Off position -Around 10-20 % NOx reduction possible under steady state testing. Preet Ferozepuria

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MAPPED / PROPORTIONATE EGR: - Very high rates of EGR flows possible (upto 30% at part load conditions). - Possible reduction of NOx by 50%. - Exhaust flow still driven by differential pressure between exhaust and intake. - Requires higher exhaust back pressures .This drawback can be overcome by having an intake throttle. - Costlier equipment .

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ECU AND SENSORS FOR EGR The EGR system is having a control valve which is controlled by the electronic control unit (ECU).The ECU output to control EGR valve depends on the three inputs: 1. Throttle Position: Throttle position is sensed by the throttle position sensor(TPS), which is mounted on the accelerator lever of on FI pump or throttle paddle in the cabin. 2. Water Temperature: Water temperature sensor is mounted on the water out let of the engine. 3. R.P.M: R.P.M is sensed by the magnetic r.p.m sensor which is mounted on the bell housing of the flywheel.

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EGR OPERATION

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TECHNOLOGY AVAILABLE COMMERCIALS VEHICLES FOR BS IV

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MULTIPLE INJECTION COMMON RAIL SYSTEM Common-rail (accumulator) fuel-injection systems make it possible to integrate the injection system together with a number of its extended functions in the diesel engine. • It thus increase the degree of freedom available for defining the combustion process. • The common-rail system's principal feature is that injection pressure is independent of engine speed and injected fuel quantity. •

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COMMON RAIL SYSTEM

Benefits of Common Rail Diesel Injection system: Major reductions in NOx and particulate matter emissions. Main characteristics of common rail fuel injection system, which give it advantage over other systems lies in. - Injection pressure is independent of engine speed (RPM) (Therefore PM is controlled at all speeds) - Injection begin and injection duration can be freely selected. Split injections up to 5 per cycle possible. - Low drive torque.

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MULTIPLE INJECTIONS IN A CR SYSTEM

Upto 6 part injection events are possible with common rail system as shown below. 1. 2. 3. 4. 5. 6.

Early pilot injection for torque increase at low speed and noise control. Close pilot injection for emissions and noise control. Main injection. Close post injection for NOx/Soot Control. Late post injection for control of λ < 1 operation. Very late post injection for HC-enrichment or exhaust gas temperature increase. Preet Ferozepuria

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SENSORS The sensors A to F are as follows: A. Crankshaft position; B. Camshaft position; C . Accelerator pedal; D. Boost pressure; E. Air temperature; F. Coolant temperature

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System design The functions of pressure generation and injection are separated by an accumulator volume. • The pressure is generated by a high-pressure plunger pump • An in-line pump is used in trucks and a radial-piston pump in passenger cars. • This injector serves as the core of this concept by ensuring correct fuel delivery into the combustion chamber •

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Hydraulic performance potential • • • • •

This system enhances the latitude for defining combustion-process patterns by separating the pressurization and injection functions. The pressures currently used are 1350 bar in passenger-car systems and 1400 bar in commercial-vehicle systems. Pilot injection and multiple injection can be used to further reduce exhaust and particularly noise emissions. The system can trigger the extremely fast solenoid several times in succession for multiple injection. Hydraulic pressure is used to augment injector-needle closing, ensuring rapid termination of the injection process.

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System application engineering on the engine No major modifications are required to adapt the diesel engine for operation with the common-rail system. • A high-pressure pump replaces the injection pump, while the injector is integrated in the cylinder head in the same manner as a conventional nozzle-and-holder assembly. • All of these features make the common-rail configuration yet another injection-system option. •

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COMMON-RAIL SYSTEM GENERATIONS • I generation CR: Pressure Upto 1350 bar • II generation CR: Pressure Upto 1600 bar •

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•

Bosch’s third generation 3.2 system, due next year, will give 1800-bar injection pressures, while 3.3 version, set for SOP in 2007, will yield 2000 bar pressure. Emission levels up to Euro 5 standards may be achieved without the need for NOx-reduction measures. The fourth generation system using novel HADI (Hydraulically Assisted Diesel Injector) due in 2008 will deliver pressures to an unprecedented 2500 bar. Denso, the world’s number – three component maker, claims that the company’s 1800 bar CRDi system, with its five injections per cycle, gives such clean combustion that DPF is unnecessary to meet EURO 4 norms.

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COMMON RAIL TYPE FUEL INJECTION PUMP – ELECTRONIC CONTROL

The ECU controls fuel delivery timing and amount Preet Ferozepuria

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PASSENGER VEHICLES DIESEL ENGINE

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ADVANTAGES OF CI ENGINE OVER SI ENGINE A diesel engine is much more efficient than a gasoline engine. A common margin is 40% more miles per gallon for an efficient turbodiesel. • A diesel engine does not require an ignition system due to the heat generated by the higher compression, • A diesel engine has a better fuel economy due to the complete burning of the fuel, and • A diesel engine develops greater torque due to the power developed from the high-compression ratio. •

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ADVANTAGES OF CI ENGINE OVER SI ENGINE Engines are durable and if properly cared for will maintain their economy. • Can use a variety of fuels and mixtures • Exhaust gases produced by diesel engine are less poisonous i.e. contain less amount of carbon monoxide • Fuel used in diesel engine is less volatile that means there is no vapor lock problems in diesel engine. •

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TORQUE ADVANTAGE OF THE CI ENGINES RELATIVE TO SI ENGINES

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The result of the higher torque of the diesel engine is that diesel engine-powered vehicles require a lower power- toweight ratio than vehicles using gasoline engines.

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Fuel Economy - Acceleration Correlations for Gasoline and Diesel Engine Vehicles

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FUEL PRICE CHART

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GROWTH OF DIESEL VEHICLES

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TECHNOLOGY AVAILABLE COMMERCIALS VEHICLES FOR BS III

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Gasoline Engines

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Training Content Standard systems of fuel injection in SI engines 1. Carburettor system for Gasoline, CNG & LPG Engines  Open loop system  Close loop system

2. Throttle body system Petrol Injection In throttle body system Gas Injection in throttle body system

3. Multi point fuel injection system or Intake –manifold injection (External A/F mixture formation) 4. Gasoline Direct Injection (GDI) system

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CARBURETOR SYSTEM A carburetor, is a device, that blends air and fuel for an internal combustion engine. • The throttle (accelerator) linkage does not directly control the flow of liquid fuel. Instead, it meters the flow of air being pulled into the engine. • The carburetor works on Bernoulli's principle: the faster air moves in the venturi during acceleration requirements, higher is its dynamic pressure and lower its static differential pressure w.r.t atmosphere. This higher pressure differential pulls more fuel for higher total charge flow requirements during acceleration. •

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CARBURETTOR SYSTEM

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LAMBDA CLOSE LOOP SYSTEM •

• • •

The closed-loop system reliably controls the Air/Fuel ratio natural gas (CNG) or propane (LPG) engines at all operating conditions to Stoichiometric. This reduces tail pipe emissions and fuel consumption. Included are the electronic control module, a high-resolution stepper motor gas flow metering valve and a wiring loom. Feedback from original or retrofit throttle position sensor (TPS), or manifold absolute pressure sensor (MAP), as well as an exhaust oxygen sensor (Lambda Sensor) is all that is needed to provide the performance needed to keep the A/F ratio to EU levels. (high efficiency catalytic converter is needed).

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THROTTLE BODY SYSTEM • • • •

It is also Called Manifold Injection or Single Point Injection (SPI) or Indirect Injection. The throttle body injection (TBI) system uses one or two injector valves mounted in a throttle body assembly. The injectors spray fuel into the top of the throttle body air horn The TBI fuel spray mixes with the air flowing through the air horn. The throttle body injection assembly typically consists of the following: throttle body housing, fuel injectors, fuel pressure regulator, throttle positioner (solenoid or stepper motor) , throttle position sensor.

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PETROL INJECTION IN THROTTLE BODY SYSTEM Injector Usually Upstream From Throttle (Air Intake Side) or In Some Cases Placed on the Opposite Side • Pressures are Low – 2 to 6 Bar. Maybe Injected Irrespective of Intake Process • Has Same Air and Fuel Mixing and Distribution Problems as Carburetor but Without Venturi Restriction so Gives Higher Engine Volumetric Efficiency • Higher Injection Pressures Compared to Carburetion – Speeds up Atomization of Liquid Fuel •

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GAS INJECTION IN THROTTLE BODY SYSTEM 

System similar to gasoline injection, but injector is of different design.

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MULTI POINT FUEL INJECTION SYSTEM •

It also Called Port Injection or Indirect Multipoint Injection (IMPI) or Semi-direct Injection .

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In this system, Fuel reaches a rail from which Electronic Injectors, positioned in each Induction Manifold Branch Just in Front of Inlet Port, inject fuel at a pressure of 2-6 bar. The injectors are activated individually for each induction pipe where it is Mixed and Stored Until IVO or after the valve has just opened.

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Stage(1)

Stage(3)

Stage(2)

Stage(4)

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Advantage 1.

More uniform A/F mixture will be supplied to each cylinder, hence the difference in power developed in each cylinder is minimum. Vibration from the engine equipped with this system is less, due to this the life of engine components is improved.

2.

No need to crank the engine twice or thrice in case of cold starting as happens in the carburetor system.

3.

Immediate response, in case of sudden acceleration / deceleration.

4.

Since the engine is controlled by ECM (Engine Control Module), more accurate amount of A/F mixture will be supplied and as a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level. Compared with carburetor engines and single-point injection systems, manifold fuel condensation is multipoint injection systems is reduced significantly resulting into less HC emission.

5.

6.

The mileage of the vehicle is also improved.

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GASOLINE DIRECT INJECTION (GDI) SYSTEM • • • • • •

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It is also Called Direct Multi-point Injection (DMPI) or Direct Cylinder Injection Fuel is injected into the combustion chamber from a central fuel rail under high pressure by electronically controlled injector. Injection May be During Intake or Compression Process To Compensate For Shorter Permitted Time For Injection/Atomization/Mixing Injection Pressure Must Be Higher Ignition is reliable as a relatively rich mixture cloud close to the spark plug is available (Choke function not required for cold start) Injector Nozzle Must Be Designed For Higher Pressure and Temperature So Must Be More Robust and Will Be Costlier Than Other Types Condensation and Wall Wetting in Intake Manifold eliminated But Condensation On Piston Crown and Cylinder Walls The direct injection cools the interior of the cylinder from evaporation of the fuel that reduces knocking at full loads. This makes it possible to increase C.R. by approximately one unit.

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GASOLINE DIRECT INJECTION (GDI) SYSTEM In contrast to conventional engines with intake manifold injection system which work under nearly all operating condition at a homogenous stoichiometric mixture, the DI engine is operated using different injection and combustion strategies. • Under hot engine at low and medium load conditions: The goal of stratified charging is to concentrate a well-prepared fuel-air mixture at the spark plug so that a locally limited, ignitable mixture arises (Lambda~1). The fuel is injected late into the compression stroke. This allows stable combustion despite overall engine running under lean operation with WOT for minimum pumping loss and maximum air flow. • For same output under cold start conditions, a homogenous slightly lean mixture would burn efficiently. This is achieved by closing the throttle valve to reduce air flow, the fuel injected quantity is also increased and injection is done during the intake stroke itself. •

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GASOLINE DIRECT INJECTION (GDI) SYSTEM

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Ward’s 10 Best Highlights Gasoline Direct Injection (GDI) Engines Ward’s 10 Best Engines 2006 Automaker

Engine

Test Vehicle

Audi

2L FSI turbocharged DOHC I-4

Audi A3

Audi

4.2L DOHC V-8

Audi S4

BMW

3L DOHC I-6

330i

5.7L Hemi Magnum OHV V-8

Dodge Charger R/T

4.6L SOHC V-8

Mustang GT

GM

2L supercharged DOHC I-4

Chevy Cobalt SS/td>

GM

2.8L turbocharged DOHC V-6

Saab 9-3 Aero

Mazda

2.3L DISI turbocharged DOHC I-4

Mazdaspeed 6

Nissan

3.5L DOHC V-6

Infiniti G35 6MT

Toyota

3.5L DOHC V-6

Lexus IS 350/td>

DaimlerChrysler Ford

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2-S Cycle 

Advantages of 2S Cycle ◦ Lightweight and compactness ◦ Less friction losses as no oil retainer, no valve train, no oil pump ◦ Low pumping losses as compared a 4S cycle ◦ Double cycle frequency and high specific power output ◦ NOx emission are less due to inherent internal EGR

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Higher Pumping Losses in a 4-S Cycle

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Low Pumping Losses in a 2-S Cycle

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2S Cycle 



Two Major drawbacks ◦ Fuel directly short-circuited in the exhaust during scavenging causing higher fuel consumption and HC emission (Can be overcome by DI) ◦ Instable combustion at part load, responsible high fuel consumption and high unburned HC Note: As significant amount of air is directly shortcircuited and lost in the exhaust, there is excess O2 in exhaust, this has two consequences: ◦ Conditions are highly favourable for HC and CO conversion in Catcon ◦ A conventional 3-way cat cannot be solution for NOx reduction

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Disadvantages of a 2-S Engine Preet Ferozepuria 127

2S GDI 

Bajaj has introduced 3-W auto-rickshaw having GDI in 2S. Compared to the conventional carburetted 2S model, its performance can be summarized as follows: ◦ 33% better furl consumption ◦ 15% more torque ◦ 25% more engine performance

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TECHNOLOGY AVAILABLE COMMERCIALS VEHICLES FOR BS IV

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DIESEL PARTICULATE FILTER (DPF) Trap oxidizer (Diesel particulate filter), reduce PM by 95%, filter + oxidation (regeneration) functions • The performance of the engine, as well as the consumption of fuel and the Co2 emissions similar levels to the ones of the functioning without filter are remained it. • The escape system, that includes a pre catalysis next to the engine and a catalysis of oxidation, was conceived to reduce all the emissions of gases, in special of hydro-carbons (HC) and carbon monoxide (CO). •

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DIESEL PARTICULATE FILTER (DPF)

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DIESEL OXIDATION CATALYSTS •

Flow through oxidation catalyst (two-way catalytic convertor) for reduction of CO and VOC (80%), and PM SOF (20-30%), does not retain PM.

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TECHNOLOGY AVAILABLE COMMERCIALS VEHICLES FOR BS V

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BHARAT STAGE-V NORMS FOR PASSENGER VEHICLES ENGINES DIESEL ENGINE Category

CO (g/kWh)

NOx (g/kWh)

PM (g/kWh)

0.50

HC+NOx (g/kWh) 0.23

0.18

0.005e

0.63

0.295

0.235

0.005e

0.74

0.350

0.280

0.005e

≤1305 kg 1305-1760 kg >1760 kg

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SELECTIVE CATALYTIC REDUCTION [SCR] CATALYST •

Ceramic materials used as a carrier (Titanium oxide)

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Active catalytic components:: oxides of base metals, zeolites & precious metals

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Base metal catalysts – lack thermal stability but inexpensive

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Zeolite catalysts – high thermal stability.

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SELECTIVE CATALYTIC REDUCTION [SCR] CATALYST GEOMETRY • •

Commonly used today are honeycomb and plate type Honeycomb type - smaller, - higher pressure drops, - plugging

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Plate type – larger, less susceptible to plugging, expensive.

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