CRDi technology
CRDi
CRDi (Common rail direct fuel injection) is the modern technique for fuel injection in both petrol and diesel engines. In this technique fuel will be kept in a separate container known as 'accumulator' since this part accumulates all the fuel before entering in to the injectors. Olden day technique involved pressuring the fuel by means of cam driven mechanisms, the cam will rotate at high speed only when the engine is operating at high load or high speed This made the mechanism to deliver high pressurized fuel only when the engine operates at high rpm (revolutions per minute), so this will result in incomplete atomization of the fuel at low speed.
In fuel injectors too the pressure with which the fuel is sprayed in to the cylinder will vary during the opening and closing of the fuel injector valves because they are controlled by springs. To overcome this technical difficulty CRDi uses injectors that works on the basis of piezoelectric effect. Piezoelectric effect is based on the principle that whenever electric pulses are sent to the piezoelectric crystal there will be a change in length in the perpendicular direction of the crystal. This change in length is enough to push the fuel in to the cylinder (combustion chamber). Since the fuel is pressurized in the accumulator itself, there is no need for the fuel injector to pressure it further. The fuel pump (accumulator) will pressurize the fuel to about 2,000 bar. One bar is equal to the normal atmospheric pressure then think of the potential of the fuel pump. CRDi has a common rail system to inject the fuel, so that every cylinder will receive the same amount of fuel during the same operating condition. Since CRDi atomizes the fuel completely there will be no improper burning of the fuel, this makes this technique noiseless. Some engine models used to name their engine as CRDe which is nothing but common rail diesel engine.
As in MPFi, CRDi technology is also controlled by ECU (Electronic Control Unit). Here in this technique ECU will keep track of the pressure in the fuel pump, so that the pressure can be increased depending upon the need. In addition to the fuel pump pressure ECU will also monitor the fuel temperature, mass of airflow, vehicle speed, throttle position etc; ECU sends the signal as pulse width, which means that how long an injector needs to open its valve to send the required amount of fuel. Invariably this technique is being used in all the diesel engine vehicles under different names. The fuel injectors that are being used in common rail diesel engine will be very small in size compared to those (injectors) used in multi port fuel injection. This smaller size component occupied less space thereby reducing the complexity of the engine and also made the engine construction to look simple. This system requires an additional fuel pump (accumulator) when compared with MPFi. This is not a big problem because the fuel pump will be located at a different location from the engine, so there won't be much complexity in the engine construction due this fuel pump.
CRDi (Common rail direct fuel injection) is the modern technique for fuel injection in both petrol and diesel engines. In this technique fuel will be kept in a separate container known as 'accumulator' since this part accumulates all the fuel before entering in to the injectors. Olden day technique involved pressuring the fuel by means of cam driven mechanisms, the cam will rotate at high speed only when the engine is operating at high load or high speed This made the mechanism to deliver high pressurized fuel only when the engine operates at high rpm (revolutions per minute), so this will result in incomplete atomization of the fuel at low speed.
In fuel injectors too the pressure with which the fuel is sprayed in to the cylinder will vary during the opening and closing of the fuel injector valves because they are controlled by springs. To overcome this technical difficulty CRDi uses injectors that works on the basis of piezoelectric effect. Piezoelectric effect is based on the principle that whenever electric pulses are sent to the piezoelectric crystal there will be a change in length in the perpendicular direction of the crystal. This change in length is enough to push the fuel in to the cylinder (combustion chamber). Since the fuel is pressurized in the accumulator itself, there is no need for the fuel injector to pressure it further. The fuel pump (accumulator) will pressurize the fuel to about 2,000 bar. One bar is equal to the normal atmospheric pressure then think of the potential of the fuel pump. CRDi has a common rail system to inject the fuel, so that every cylinder will receive the same amount of fuel during the same operating condition. Since CRDi atomizes the fuel completely there will be no improper burning of the fuel, this makes this technique noiseless. Some engine models used to name their engine as CRDe which is nothing but common rail diesel engine.
As in MPFi, CRDi technology is also controlled by ECU (Electronic Control Unit). Here in this technique ECU will keep track of the pressure in the fuel pump, so that the pressure can be increased depending upon the need. In addition to the fuel pump pressure ECU will also monitor the fuel temperature, mass of airflow, vehicle speed, throttle position etc; ECU sends the signal as pulse width, which means that how long an injector needs to open its valve to send the required amount of fuel. Invariably this technique is being used in all the diesel engine vehicles under different names. The fuel injectors that are being used in common rail diesel engine will be very small in size compared to those (injectors) used in multi port fuel injection. This smaller size component occupied less space thereby reducing the complexity of the engine and also made the engine construction to look simple. This system requires an additional fuel pump (accumulator) when compared with MPFi. This is not a big problem because the fuel pump will be located at a different location from the engine, so there won't be much complexity in the engine construction due this fuel pump.
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