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Common sense for diesel engine

When customer choosing commercial vehicle products, will face the choice of petrol and diesel power, so why do most commercial vehicles choose diesel? How much do you understand the common sense of diesel engine? let’s learn some preliminary understanding of diesel engine together.

1) What do the power and torque respectively represent?

Power refers to the object the work done in a unit time, which is the object to tell work done efficiency. Watt (w) is the international standard unit, 1 kw = 1000 w, 1000 joules of work within one second, its power is 1 kw. We often use maximum power to describe the dynamic performance of the car. The power, commonly known as Horsepower (HP) or kilowatts (kw), 1 horsepower is equal to 0.735 kw.

The rated power of the engine generally refers to the engine carrying the necessary parts during the highest power operation. The effective power of the engine refers to the net output power from crankshaft.

Torque, the size of moment of force in physics, which is equal to torque force times arm of force, and the international unit is cattle • m (N, m). In addition we can also see k. gm as the torque unit, 1k.gm = 9.8 N m, torque is often referred to as force. The greater the power, the greater the torque, the higher power drive the car as well.

Simply stated as follows:
Power – how fast can run, how heavy can drive
Torque – how fast to speed up, how steep slope can climb
Power = torque x speed

2) Why the diesel engine has strong torque?

Relative to the gasoline engine, the basic conditions for the same case, the power of diesel engine is more powerful. As is known to all, the power from petrol engine is by the spark plug ignites mixed gas, but mixture gas is not easy to ignite for diesel engine. So the diesel engine use “compression ignition”, which is also the important characteristic different from gasoline engine.

Diesel engine compress the air first (some diesel engine compression ratio can reach to 20:1), then inject the atomized diesel to the high temperature and pressure air to cause explosion to finish work done. Because of the large diesel engine compression ratio, the reaction is also big, namely we often say as big torque. The gasoline engine adopt “light” the compressed gas mixture (normally the compression ratio is 10:1), with the blast work done. Because of the gasoline engine mixture has a lower density than diesel engine before the “compression ignition “, so the reaction is lower than diesel engine after the explosion, namely that is why the diesel engine has more powerful explosive power than gasoline engine.

3) Why diesel engine is more fuel-efficient?

Firstly, for one litre fuel, diesel’s combustion heat is more than 9000 calories, and only 7000 calories for gasoline. Secondly, under the condition of the engine power is equal to torque, diesel engine has less fuel consumption than gasoline because of the fuel heating value. In addition, cause the diesel engine has higher compression ratio, so the energy conversion efficiency is also higher than gasoline engines.

4) Why can Turbo-charge increase the power and torque?

Diesel engine can increase the intake air quantity through the turbine, to improve the driving force of the work done. Namely take use of the high-pressure exhaust fumes as power, which drive the other side shaft to “suck” more air through the inlet turbine, to increase the effect of explosion power and torque. The current high-end diesel engine has generally adopted the turbocharged technology.