Common rail direct injection

Common rail direct injection

1. Common Rail Direct Injection Submitted To- Mr. Amit Kumar Submitted By- Yashwardhan Sahi 140970104064

2. Contents Introduction History Operating Principle Working of CRDI Components of CRDI Diff. b/w direct & indirect injection Advantages & Disadvantages Applications Acronyms of CRDI References Remarks

3. INTRODUCTION CRDI (Common Rail Direct Injection) CRDI stands for Common Rail Direct Injection meaning, direct injection of the fuel into the cylinders of a diesel engine via a single, common line, called the common rail which is connected to all the fuel injectors.

4. Whereas ordinary diesel direct fuel-injection systems have to build up pressure anew for each and every injection cycle, the new common rail (line) engines maintain constant pressure regardless of the injection sequence. This pressure then remains permanently available throughout the fuel line. The engine's electronic timing regulates injection pressure according to engine speed and load. The electronic control unit (ECU) modifies injection pressure precisely and as needed, based on data obtained from sensors on the cam and crankshafts. In other words, compression and injection occur independently of each other. This technique allows fuel to be injected as needed, saving fuel and lowering emissions.    More accurately measured and timed mixture spray in the combustion chamber significantly reducing unburned fuel gives CRDI the potential to meet future emission guidelines such as Euro V. CRDI engines are now being used in almost all Mercedes-Benz, Toyota, Hyundai, Ford and many other diesel automobiles.

5. History The common rail system prototype was developed in the late 1960s by Robert Huber of Switzerland and the technology further developed by Dr. Marco Ganser at the Swiss Federal Institute of Technology in Zurich, later of Ganser-Hydromag AG (est.1995) in Oberägeri . The first successful usage in a production vehicle began in Japan by the mid-1990s. Modern common rail systems, whilst working on the same principle, are governed by an engine control unit (ECU) which opens each injector electronically rather than mechanically. This was extensively prototyped in the 1990s with collaboration between Magneti Marelli , Centro Ricerche Fiat and Elasis . The first passenger car that used the common rail system was the 1997 model Alfa Romeo 156 2.4 JTD, and later on that same year Mercedes-Benz C 220 CDI.  

6. Common rail engines have been used in marine and locomotive applications for some time. The Cooper-Bessemer GN-8 (circa 1942) is an example of a hydraulically operated common rail diesel engine, also known as a modified common rail. Vickers used common rail systems in submarine engines circa 1916. Early engines had a pair of timing cams, one for ahead running and one for astern. Later engines had two injectors per cylinder, and the final series of constant-pressure turbocharged engines were fitted with four injectors per cylinder. This system was used for the injection of both diesel oil and heavy fuel oil (600cSt heated to a temperature of approximately 130 °C). The common rail system is suitable for all types of road cars with diesel engines, ranging from city cars such as the Fiat Nuova Panda to executive cars such as the Audi A6.

7. Operating Principle   Solenoid or piezoelectric valves make possible fine electronic control over the fuel injection time and quantity, and the higher pressure that the common rail technology makes available provides better fuel atomisation. 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, thus reducing its explosiveness and vibration, as well as optimizing injection timing and quantity for variations in fuel quality, cold starting and so on.

8. Components of CRDI 1. PRE SUPPLY PUMP The electric fuel pump comprises of:  Electric Motor  Roller-Cell Pump   Non Return Valve - electric             - roller              - gear   Rail-pressure sensor (RDS). Injector 2. Pressure-control valve (DRV) Responsible for maintaining the pressure in the rail at  a constant level .

9. 3. High pressure pump The pump plunger moves downwards The inlet valve opens The fuel is drawn in to the  pumping element chamber(suction stroke ). At BDC, the inlet valve closes. The fuel in the chamber can be compressed by the upward moving plunger. High- pressure accumulator (Rail ). 4. 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 Rail-pressure-sensor(RDS) Inputs the information to the ECU. Measures the pressure in the rail.

10. Working of CRDI A high-pressure pump generates pressurised fuel. The pump compresses the fuel at the pressures of about 1,000 bar or about 15,000 psi. It, then, supplies the pressurised fuel via a high-pressure pipe to the inlet of the fuel-rail.

11. From there, the fuel-rail distributes it to the individual injectors which then inject it into the cylinder's combustion chamber. Most modern CRDI engines use the Unit-Injector system with Turbocharger which increases power output and meets stringent emission norms. This improves engine power, throttle response, fuel efficiency and controls emissions. Barring some design changes, the basic principle & working of the CRDI technology remains primarily the same across the board. However, its performance depends mainly on the combustion chamber design, fuel pressures and the type of injectors used.

12. Difference b/w Direct & Indirect Injection Direct Injection (DI) 1. Injection pressure is higher (21 kg/cm^2) in this case as compare to IDI because fuel atomisation is solely depend upon pressure of injection.

13. 2. This type of engines are easy to start in cold also. 3. Fuel injection nozzle have multiple holes as high atomisation and mixing is required because swirling of air is less in this case. 4. Thermal efficiency is higher as compare to IDI engine. Indirect Injection (IDI) 1. Injection pressure is low as compare to DI as most atomizing is achieved using pressure of air from pre-combustion chamber. 2. Glow plug is required to start the engine in cold start. 3. Single orifice nozzle is used. 4. Heat losses are more due to large wall area so thermal efficiency get reduced as compare to DI. 5. High compression ratio is possible in IDI as compared to DI.

14. Advantages & Disadvantages Advantages 1. CRDI engines are advantageous in many ways. Cars fitted with this new engine technology are believed to deliver 25% more power and torque than the normal direct injection engine. 2. It also offers superior pick up, lower levels of noise and vibration, higher mileage, lower emissions, lower fuel consumption, and improved performance. 3. In India, diesel is cheaper than petrol and this fact adds to the credibility of the common rail direct injection system.   Disadvantages Like all good things have a negative side, this engine also have few disadvantages. The key disadvantage of the CRDI engine is that it is costly than the conventional engine. The list also includes high degree of engine maintenance and costly spare parts. Also this technology can’t be employed to ordinary engines.

15. Applications The most common applications of common rail engines are marine and locomotive applications. Also, in the present day they are widely used in a variety of car models ranging from city cars to premium executive cars.

16. Some of the Indian car manufacturers who have widely accepted the use of common rail diesel engine in their respective car models are the Hyundai Motors, Maruti Suzuki, Fiat, General Motors, Honda Motors, and the Skoda. In the list of luxury car manufacturers, the Mercedes-Benz and BMW have also adopted this advanced engine technology. All the car manufacturers have given their own unique names to the common CRDI engine system. However, most of the car manufacturers have started using the new engine concept and are appreciating the long term benefits of the same. The technology that has revolutionized the diesel engine market is now gaining prominence in the global car industry.  

17. Acronyms used by different manufacturers for CRDI Acronym Company CDI Mercedes Benz CRDI Hyundai CR4, DiCOR Tata CRDE Mahindra D BMW, Volvo DDiS Suzuki D-4D Toyota DCi Renault, Nissan DI-D Mitsubishi i-CTDi , i -DTEC Honda JTD Fiat VCDi Chevrolet TDCi Ford TDI Volkswagen

18. REFERENCE www.google.com www.wikipedia.com www.seminarlinks.blogspot.com Textbook of Automobile Engineering

19. THANK YOU