By KEDAR D. GOKHALE ME 02 M 094 (Tata Technologies Ltd)
I.C. Engines; Still a dominant prime mover for automobiles ! However Challenges exist !
Exhaust Emissions reduction (Air Pollution) Better NVH & Driveability Fuel Economy improvement (CO2 - Global warming) Safety aspects Competitive Costs
(..Contd)
Direct Injection Diesel Engine with Flexible FIE viz. Common Rail System can offer: ü
Reduced Combustion Noise
ü
Diffused NOx – PM Trade-off
ü
High specific power output Hence Common Rail
“
”
has become a buzzword in Automotive Industry.
1) Start Diesel Injection... - at the right Moment (Injection Timing) - in the right Quantity (and Rate !) - in the right Form (Atomization & Penetration) - Consistently - Cycle by Cycle - Cylinder to Cylinder - Over a Period of Time 2) End the Injection sharply.
n
Mechanical Systems n
- Pump – Line – Injector n n n
n
n
Electronic Systems n
In line Type Rotary Distributor Type Unit Pump Type
Unit Injectors
- Pump – Line - Injector n n n
Electronic Inline Type Electronic Rotary Type Electronic Unit Pump
n
Electronic Unit Injector
n
Common Rail System n
Solenoid Operated n n
n
Unbalanced Servo Valve Balanced Servo valve
Piezo Operated n n
Servo valve type Direct acting type
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Common Rail System is a modular, e controlled diesel injection system offering closed loop flexible control of Injection
A Rail which is common for all cylinders, stores the fuel at high pressure and delivers it to each cylinder at almost constant pressure. Hence the name Common Rail “
”
“
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01 = H.P.Pump 02 = Element Shutoff valve 03 = Rail Pressure Sensor 04 = Pressure-limiter Valve 05 = H.P. Accumulator (Rail) 06 = Injector 07 = Phase sensor 08 = HFAMS 09 = Fuel Filter 10 = Boost Pressure Sensor 11 = Feed Pump 12 = Bi-Metal valve 13 = Coolant temperature Sensor 14 = Turbocharger 15 = Return line valve 16 = Speed Sensor 17 = Vacuum Valve 18 = EGR Pressure Transducer 19 = Vacuum Reservoir 20 = Fuel Tank 21 = In Tank Fuel Pump 22 = Battery 23 = Accelerator Pedal Position Sensor
High Pressure Pump (Bosch)
High Pressure Rail
C.R. Injector
01: Fuel Return 02: Solenoid Connector 03: Solenoid Assembly 04: H.P. Fuel Inlet 05: low pressure zone 06: Ball Valve 07: Fuel Path to Nozzle 08: Fuel Path to Ball Valve 09: Needle Stem 10: Nozzle 11: Needle
v v v v v
Heterogeneous Combustion Smoke limited Power Output Always Lean (Overall AFR 20 ~ 80) Criticality of In Cylinder Flows Quality Governed Fuel Injection Parameters are Critical...
Common Rail advantages: n
Injection Pressure fairly independent of Engine Speed & Load.
n
Multiple Injections (Pilot, Main, Post) for better emissions & NVH.
n
Commonization of parts across Variants (Diesel & Gasoline)
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Flexible and accurate Timing Control
n
Flexible Injection Rate Control
n
Flexible Torque Curve Shape Control
n
Additional control on n
EGR
n
Turbocharger
n
Particulate Trap
n
Improved Cycle to Cycle Control
n
Improved Cylinder to Cylinder control
n
Additional Parameters Processing capabillity
Evolution of DI Diesel Engine for Passenger Cars Example: Fiat 1.9 L TCIC Engine (Bosch) Common Rail Injection
Max. Injection Pressure: 1350 bar No Injection Rate Shaping Electronic 3 Pilot Injn 1.5 mm /St @ 500 bar Distributor Pump Swirl Ratio : 2.5 Max. Injection Pressure: 900 bar C.R. : 18.5 Mechanical Two Spring Injector(Rate Shaping) BHP / Litre : 57.1 Distributor Pump No Pilot Injection Torque Nm / Litre : 130 Swirl Ratio : 3.0 Max. Injection Pressure: 700 bar C.R. : 20 No Injection Rate Shaping BHP / Litre : 51.7 No Pilot Injection Torque Nm / Litre : 100 Swirl Ratio : 3.5 C.R. : 18 BHP / Litre : 47.6 Torque Nm / Litre : 95
Application
Bore x Stroke
1
DuraTorq, 4 cyl CR DI, Ford Mondeo 16V DOHC, VGTCIC
86 x 8 6
1998
2
Merc, 4 cyl CRDI, 16V DOHC, TCIC
Mercedes C 200 CDI
88 x 8 8.3
3
Hyundai, 3 cyl, CRDI, 12V DOHC
Hyundai Accent
4
Toyota, 1.4D-4D, 4 cyl CRDI, 8V SOHC
Sr Engine Description
5 Hyundai 4 Cyl C RD I
Engine C.R. cc
Max Power kW (hp) @ RPM
Max Torque Nm @ RPM
BHP per Litre
19
83 (113) @ 4000
280 @ 1900
57
2148
18
84 (114) @ 4200
250 @ 2300
53
83 x 92
1493
18
60 (82) @ 4000
187 @ 2000 ~ 2700
55
Toyota Yaris Verso D-4D
73 x 8 1.5
1364
19
55 (75) @ 4000
170 @ 2000 ~ 2800
55
Terracan
97.1 x 9 8
2902
19
110 (150) @ 3800
333 @ 2000
51.7
6
Fiat, 4 cyl, CRDI, 16V DOHC, Multijet
Fi at Punto
69.6 x 8 2
1251
N.A.
51 (70) @ 4000
180 @ 1750
56
7
Fiat, 4 cyl, CRDI, 8V SOHC, Multijet
Fiat P unto
82 x 9 0.4
1910
18
74 (100) @ 4000
259 @ 1750
52.3
BHP / litre for Typical DI Diesel Engine with Mechanical FIE = 45~48
Engine Feature
Present DI Diesel
Emerging DI Diesel
Combustion System
2 Valves per cylinder
4 Valves per cylinder
Fuel Injection Mechanical Common Rail System (Rotary) Pump Aftertreatment Boosting System
Oxidation catalyst
Lean Nox Catalyst
Fixed geometry Variable Turbo Geometry turbo
Actuator
Pneumatic
Electric
Base Structure
C.I. & Aluminium
Aluminium
Advantage over Present Nox
P.M.
a
a
a
a
NVH
a
Power Density
Fuel economy
a
a
a
a
a
a
a a
a
a
a a
