1. CRDI Engine technologyby
P. Mohamed Iqbal

2. Overview Introduction Principle Working Features
Scope for further development
Conclusion

3. Introduction
The country among other things has seen an enormous development in engines used in cars also.
The Diesel engines have also undergone a sea change from the time Rudolf Diesel invented it way back in 1892.
Today Common Rail Direct Injection (CRDI) is the order of the day.

4. CRDI Engine

5. Principle
Unlike in conventional diesel engines, the fuel is fed into the common tube or rail and high pressure is maintained.
This allows fuel to combine with air much more efficiently.
It features high-pressure fuel rail feeding individual solenoid valves as opposed to low-pressure fuel pump feeding injectors.

6. Layout of a CRDI Engine

7. The Common Rail Sub functions
Low –pressure circuit comprises of:
Fuel tank ,Pre-supply pump, Fuel filter, And the respective connection lines.

8. Low –pressure circuit
The low –pressure circuit is responsible for transporting the fuel to the high –pressure circuit

9. The Common Rail Sub functions
High –pressure circuit comprises:
High – pressure pump with pressure – control valve
The high – pressure accumulator (Rail )with the rail –pressure sensor
Injectors, and
The respective high – pressure connection lines.

10. The high – pressure circuit
It is the responsibility of the high
pressure circuit to generate a constant
unvarying high pressure in the high
pressure accumulator (the rail) and to
inject the fuel through the injectors into
the engine’s combustion chambers.

11. The Common Rail Sub functions
ECU and sensors
The common rail ECU evaluates the signals from the following sensors.
Crankshaft – speed sensor, Camshaft sensor,
Accelerator-pedal travel sensor

12. The Common Rail Sub functions
The common rail ECU evaluates the signals from the following sensors:
Boost – pressure sensor, Air temperature sensor,
Air – mass meter, and Rail pressure sensor.

13. The Common Rail Sub functions
ECU and sensors
The sensor are responsible for measuring important physical quantities. The ECU calculates injected fuel quantity, start of injection, duration of injection, and rate of discharge curve, as well supervises the correct functioning of the injection system as a whole.

14. COMMON RAIL FUEL INJECTION SYSTEM DESIGN
PRE SUPPLY PUMP
Transports fuel from the fuel tank to the high pressure pump.
An electric fuel pump is used for this purpose in the CRFIS.
When the electric fuel pump is switched off, the supply of fuel is interrupted and the engine stops.

15. PRE SUPPLY PUMP The electric fuel pump comprises of: 1.Electric Motor
2.Roller-Cell Pump
3.Non Return Valve

16. PRE SUPPLY PUMP The roller cell is driven by an electric motor.
Its rotor is mounted eccentrically and provided with slots in which movable rollers are free to travel.

17. PRE SUPPLY PUMP
The rollers are forced against the base plate by rotation and by fuel pressure .
The fuel is transported to the outlet openings on the pump’s pressure side.

18. PRE SUPPLY PUMP variants
Gear type fuel pump
The drive gear wheel is driven by the engine .
Delivery quantity is directly proportional to engine speed .
Shut off is by means of an electromagnet..

19. High- pressure pump The pump plunger moves downwards
The inlet valve opens
The fuel is drawn in to the pumping element chamber(suction stroke)

20. High- pressure pump At BDC, the inlet valve closes
The fuel in the chamber can be compressed by the upward moving plunger.

21. High- pressure pump
An electromagnet is used for pumping element switch-off.

22. High- pressure accumulator (Rail)
Store fuel
Prevent pressure fluctuations

23. High- pressure accumulator (Rail)
Rail is a forged-steel tube.
ID is approx.. 10mm
Length is between 280 and 600mm
The volume must be “ as small as possible, as large as necessary”

24. Pressure-control valve (DRV)
Responsible for maintaining the pressure in the rail at a constant level.

25. Rail-pressure sensor (RDS)
Measures the pressure in the rail
inputs the information to the ECU
RDS should provide extremely precise measured values.
RDS is mounted directly on the rail.

26. Injector
Injects exactly the correct amount of fuel in to the combustion chamber at precisely the right moment in time

27. Injector The injector is equipped with:
2/2 electromagnetic servo valve
Nozzle
Valve control chamber
Return line

28. Injector The essential forces for correct functioning are:
Nozzle-spring force
Valve spring force
Electromagnet force
Force due to the pressure in the valve-control chamber
Force due to the pressure in the nozzle needle

29. ECU with sensors Common Rail is an EDC controlled injection system
The ECU controls & monitors the complete injection process
The sensors delivers all the measured values which are required in the process

30. COMMON RAIL FUEL INJECTION SYSTEM
Summary
Components of CRFIS are:
Pre-supply pump
High-pressure pump
High-pressure accumulator(rail)
Pressure-control valve
Rail-pressure sensor
Injectors
ECU with sensors

31. Working
Solenoid valves make possible fine electronic control over the injection time and amount, and the higher pressure that the common rail technology makes available provides better fuel atomization. In order to lower engine noise, the engine's electronic control unit can inject a small amount of diesel just before the main injection event ("pilot" injection), thus reducing its explosiveness and vibration, as well as optimizing injection timing and the process continues

32. Features Direct injector Spiral-shaped intake port Integrated port
Air flow metering
Multiple Pilot injection and Post injection
Powerful Microcomputer
Newly-developed catalytic converters
Reduced noise levels

33. Direct injector
A fuel injector is nothing but an electronically controlled valve.

34. Spiral-shaped Intake port
Provides optimum swirl and even distribution of fuel.

35. Integrated port
Integrated port is used for exhaust gas recycling. There are three advantages to this system
eliminates external pipes which are subject to vibration
quicker engine warm-up
better combustion.

36. Air flow metering
It gives exact analysis of the air-mass that is being taken in.
Due to this metering system, the microcomputer that controls engine timing receives precise data.

37. Multiple Pilot injection and Post injection
Pilot injections is small doses of fuel made prior to the main injection which help to smoothen the sharp combustion character.
Post injection is a similarly small dose of fuel injected after the main injection to reduce particulates.

38. Powerful Microcomputer
The microcomputer regulates the amount of time the valves stay open and thus the amount of fuel injected, depending on operating conditions and how much output is needed.

39. Newly-developed catalytic converters
Besides electronically-controlled exhaust-gas recycling which contributes to lower nitrous oxide emissions, CRDI engines are equipped with catalytic converters near the motor and emission control devices on the underbody. These vouch for a high degree of efficiency.

40. Reduced Noise levels
The Electronic control and multiple injections reduced noise to a great extent

41. Scope for further development
Use of different fuels for zero emissions and better engine performance
By using different fuels and cetane improvers, maximum torque can be obtained
Lowering the cost
Closed-loop control injection with ion sensing technology

42. Conclusion
CRDI technology revolutionized diesel engines. It has changed the way one looks as diesel cars by providing the above said advantages.

43. Advantages -More power is developed -Increased fuel efficiency
-More stability
-Pollutants are reduced
-Particulates of exhaust are reduced
-Exhaust gas recirculation is enhanced
-Precise injection timing is obtained
-Pilot and post injection increase the combustion quality
-The powerful microcomputer makes the whole system more perfect

44. Manufacturers of CRDI engine
The car makers refer to their common rail engines by their own brand names. Some of them are
BMW's D-engines
Mahindra's CRDe
Tata's DICOR
Honda's i-CTDi
Hyundai-Kia's CRDi etc

45. References International Journal of Automotive Technology
Approaches to Automotive Emissions Control
Magazines: Auto week, Automobile India

46. Thank you
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