Common Rail is basically an advanced fuel injection system which uses a tube to inject pressurized fuel directly into the car engine while maintaining a constant high pressure. The pressure that is present in the engine ensures that the fuel breaks down while administering the injection which helps to mix with the air. This helps to reduce the pollution normally caused by automobiles. When the air and the fuel is mixed the harmful emissions from the vehicle drops. There is an interesting history behind this engine’s emergence.
The first prototype of the common rail was introduced by Robert Huber in Switzerland in 1960. The design was taken ahead by Dr. Marco Ganser at the Swiss Federal Institute in Zurich. It was introduced to the international market as a product in the 1990s. During that time, it was fitted in with a commercial vehicle and sold.
The principle of the CRDi and the conventional engines is not all that different. The only difference is the traditional engine was controlled mechanically and the CRDi is controlled by an electronic control unit. The unit regulates the amount of fuel injected as well as the pressure utilized and required for both injection and combustion. The CRDi works with alongside the solenoid valve. This is an electromechanical valve that controls the flow of liquid or gas by stopping or running the flow of electric current. This valve is capable of controlling the quantity and the time of the fuel engine and calculate the amount of high pressure which is generated by the engine. The first few cars to be put on the market, with this engine were Alfa Romeo 156 in 1997 and Mercedes Benz C 220.
Working of this Engine
In a conventional engine system, the high pressure fuel pump stores a reservoir of fuel at a pressure of at about 29,000 pound-force per square inch (psi) in a common rail. This rail is, in reality, a tube which divides into a fuel injector valve which is fully computer controlled and which has a precision-machined nozzle and a plunger which is driven by a solenoid valve. With the help of an on board computer, the engine regulates the fuel quantity and pressure. It also notes the time when the injection is actually injected and at the same time, increases the pressure at which the fuel is injected. This usually results in better combustion and fuel atomization which leads to lower exhaust emissions, increased fuel efficency and lower fuel consumption.
Like every new technology, CRDi has its own pros and cons. It has a couple of positive points such as, it offers 25% more power and torque as compared to convential engines. In countires such as India, since diesel is cheaper than petrol this form of injection works as an advantage. The disadvantage is, this form of engine is costlier than a conventional engine.
In the recent times, most big names in the automobile industry have adopted this engine. Some of these names are Fiat, Mitsubishi, Hyundai, Ford, Toyota, General Motors and so on.
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