Three Elements of Gasoline Engines


1. Good air-fuel mixture for automobiles

(1) Gasoline is vaporized and sufficiently mixed with air In order for gasoline to completely burn, it must be sufficiently vaporized and mixed with air.

(2) Proper air-fuel mixture Automobiles are used under various operating conditions and there is a change in the engine operating condition, the required air-fuel mixture changes as well.

When the air temperature changes from high to low.

When the driving surface changes from flat ground to a steep incline and a heavy load is applied to the engine.

When the engine speed changes widely from idling to high speed for acceleration.

2. Air-fuel ratio

The air-fuel ratio is the ratio of the mass of air to fuel. When the amount of air is too great or too small, the gasoline does not burn well, resulting in incomplete combustion. There is a minimum of 14.7 parts air required to completely burn 1 part gasoline. This is called the theoretical air-fuel ratio. However, in actual gasoline engines, even though the gasoline is injected to meet the theoretical air-fuel ratio, not all the gasoline can be vaporized and mixed with the air. For that reason, under some conditions a richer air-fuel mixture is necessary.

3. Air fuel ratio and driving conditions

(3) At startingAt starting, the walls of the intake manifold, the cylinders and the cylinder head are cold, causing the fuel sprayed by the injectors to adhere to them. In this case, the air-fuel mixture in the combustion chamber becomes lean. Therefore, the rich air-fuel mixture is required.

(4) Warming-upThe lower the coolant temperature is, the vaporized condition of the gasoline becomes worse, causing ignition worse. Therefore, the rich air-fuel mixture is required.

(5) When acceleratingWhen the accelerator pedal is depressed, a fuel supply lag occurs by load change, resulting in a leaner fuel mixture. Therefore, an additional amount of fuel is injected to the mixture.

(6) When cruising (constant speed)After the engine is completely warmed up, the fuel mixture supplied to the engine is very close to the theoretical air-fuel ratio.

(7) Under heavy loadsWhen a higher output of power is needed, a slightly richer fuel mixture is supplied to the engine to lower the burning temperature and ensure that all of the intake air is used in combustion.

(8) When deceleratingAs engine output is not needed, fuel is cut-off in a part of this driving condition in order to clean exhaust gasses.

Related Post