2. What is CRDI ? CRDI stands for Common Rail Direct Injection.
Direct injection of the fuel into the cylinders of an engine via a single, common line, called the common rail which is connected to all the fuel injectors.
Instead of providing separate piston pumps for fuel supply, the common rail alone supplies high pressure fuel to each cylinder.

3. The Technology
Whereas ordinary diesel direct fuel-injection systems have to build up pressure anew for each and every injection cycle, CRDI engines maintain constant pressure regardless of the injection sequence.
This pressure then remains permanently available throughout the fuel line.
The electronic control unit (ECU) modifies injection pressure precisely as needed, based on data obtained from sensors on the cam and crankshafts. ie compression and injection occur independently of each other.
This technique allows fuel to be injected as needed, saving fuel and lowering emissions.

4. PRINCIPLE OF CRDi IN DIESEL ENGINES
is named as GDI( Gasoline Direct Injection)
Introduced to remove the drawbacks of carbureted and MPFI systems
Main advantage is that even petrol engines can be run under the very lean mixture ratio of 50:1.

5. Layout of a typical CRDI system

6. Differences between DI and CRD
Constant pressure regardless of the injection sequence.
Fuel is supplied directly to a common rail from where it is injected directly onto the cylinder head
High Pressure of about (1600 bar) , Improved pulverization
Electronic engine management system continually adjusts the peak fuel pressure according to engine speed and throttle position
Compression and injection occur independently of each other

8. Electronic Control Unit
ECU monitors Engine variables such as
Temperature
intake pressure
RPM
air mass intake
demand for power (from accelerator)
provides real time control
modifies injection pressure precisely as needed , based on data obtained from cam and crankshaft.

9. Electronic Fuel Injector
• Electromagnet moves the plunger - opening rapid solenoid valve
• Injector pulse width controlled by ECU

10. CHARACTERISTICS
Spiral shaped Intake port for optimum swirl of air entering cylinder – spiral port induces optimum swirl in the intake air leading to more efficient mixing and combustion of fuel inside cylinder
Integrated port at cylinder head for exhaust gas recycling – building up input air temperature, reducing vibrations and cooler exhaust

11. Precise Air Flow Metering
Air-flow meter located in front of the turbocharger's compressor permitting an exact analysis of the air-mass that is being taken in.
•Air mass alters depending on temperature or atmospheric pressure.
• The microcomputer that controls engine timing receives precise data.
• It is thus able to regulate exhaust-gas recycling according to engine load and speed in the interest of lowering nitrous oxide and particle emissions

12. Precise Air Flow Metering
Air-flow meter located in front of the turbocharger's compressor permitting an exact analysis of the air-mass that is being taken in.
•Air mass alters depending on temperature or atmospheric pressure.
• The microcomputer that controls engine timing receives precise data.
• It is thus able to regulate exhaust-gas recycling according to engine load and speed in the interest of lowering nitrous oxide and particle emissions

13. Multiple Pilot And Post Injection
Leading to smoother compression and expansion-- reducing noise levels
More efficient combustion and burning up of fuel leading to quieter engine cycles
Reduces unburnt HC , NOx and CO and particles in exhaust Visit

14. CRDI - Future Trends
Ultra-high pressure common-rail injection (1800 bar) generating ideal swirl in the combustion chamber allowing the air/fuel mixture to form a perfect vertical vortex - uniform combustion and greatly reduced NOx emissions
CRDi and Particle Filter - To reduce particle emissions from exhaust
CRDi and closed-loop control injection - Using ion sensor to provide real-time combustion data for each cylinder such as temperature and pressure.