3 introductionThe common rail system of fuel injection was used in marine diesel engines during the early and mid-19th century.The common rail system of fuel injection is a simple and efficient system.The recent trend in the automobile industry is the usage of common rail direct fuel injection systems in some modern vehicles.Some of the engines in the automobile sector introduce this common rail system of injection not only in diesel engines, but also in petrol/gasoline engines.
4 Why it is called crdi?It is a new technology and it is called common rail direct injection because there is only one plunger in the pump which supply fuel to the rail from where fuel is injected to the different nozzles (injectors).
5 Demand On Modern Diesel Engine Development Low fuel consumption.Low pollution emission.Quiet running engine.Improved engine performance
6 Common Rail Fuel Injection System And Its Function Provide the diesel engine with fuel.Generate the high pressure needed for fuel injection and distribute the fuel to the individual cylinders.Inject precisely correct amount of fuel at exactly the right moment in time.In contrast to other injection system Common rail fuel injection system is an accumulator injection system.
7 How Does A CR System Function? COMMON RAIL FUEL INJECTION SYSTEMLow Pressure CircuitHigh Pressure CircuitECU With Sensors
8 Working Of CRDi. Low –pressure circuit comprises of: Fuel tank . Pre-supply pump.Fuel filterAnd the respective connection lines.
9 High –pressure circuit comprises: Working Of CRDiHigh –pressure circuit comprises:High – pressure pump with pressure – control valveThe high – pressure accumulator (Rail )with the rail –pressure sensorInjectors, andThe respective high – pressure connection lines.
10 Working Of CRDi ECU and sensors The common rail ECU evaluates the signals from the following sensors.Crankshaft – speed sensor, Boost – pressure sensor.Camshaft sensor, Accelerator-pedal travel sensor.Air temperature sensor.Air – mass meter and Rail pressure sensor.
11 Components of CRDi PRE SUPPLY PUMP - electric - roller - gear Rail-pressure sensor (RDS).InjectorHigh pressure pump.High- pressure accumulator (Rail).Pressure-control valve (DRV)
12 Pre Supply Pump The electric fuel pump comprises of: 1.Electric Motor 2.Roller-Cell Pump3.Non Return Valve
13 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.
14 PRE SUPPLY PUMP 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.
15 High- pressure pump The pump plunger moves downwards The inlet valve opensThe fuel is drawn in to the pumping element chamber(suction stroke)At BDC, the inlet valve closesThe fuel in the chamber can be compressed by the upward moving plunger.
16 Pressure-control valve (DRV) Responsible for maintaining the pressure in the rail at a constant level.
17 Rail-pressure sensor(RDS) Measures the pressure in the rail.Inputs the information to the ECU.
18 ECU with Sensors Common Rail is an EDC controlled injection system The ECU controls & monitors the complete injection processThe sensors delivers all the measured values which are required in the process