What is the difference between internal circulation and external circulation of automobiles?

One of the main functions of adjusting the air flow and temperature in the car is the internal circulation and the external circulation. Many novice friends are often confused by the complicated function buttons on the air conditioning panel, and it is even more unclear when to use the internal circulation. When to use the outer loop?

The inner circulation and the outer circulation are two separate buttons on the air conditioning control panel, which is easy to understand. The inner circulation means that the air inside the car circulates when it is closed. The icon is an arrow with a circulation inside a closed car. The external circulation is to flow the air outside the car into the car. The icon is an open car with an air arrow pointing to the inside.

Let's talk about this external circulation first. Its function is to flow the fresh air outside the car into the car and ventilate the car. If we don't use external circulation, we usually open the window directly to breathe. In fact, the purpose is the same, but the effect is different.

first of all, if you open the window for air, this air will come in directly. If there is wind and sand exhaust on the road, it will all enter the car together. The air circulating in is filtered by the air conditioner filter of the car first, and then enters the car;

In addition, if the car is driving at a high speed, especially at a high speed, if the wind coming in by opening the window is strong and uncomfortable, the wind circulating outside will be much milder.

Finally, open the window at high speed, even if you only open a small gap, it will have a great impact on fuel consumption, because when the car is at high speed, about 6% of fuel consumption is to overcome the wind resistance, and the wind resistance is even greater when you open the window.

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The ventilation mode of external circulation is more scientific, which is that there is an air inlet under our front windshield wiper and an air outlet at the rear of the car, that is, when we drive at high speed, the wind comes from the front of the car and then is discharged from the rear. This entry and exit are all along the pressure of wind resistance, so it has little effect on fuel consumption and can even reduce wind resistance.

so, the first situation that requires us to go outside is driving at high speed. In addition, if we are new cars, we should always circulate outside and convect harmful substances such as formaldehyde and benzene out of the car, especially when it is cold in winter and it is inconvenient to open the window; There are also people who like to smoke in the car and circulate outside; In addition, if the car has been circulating for a long time, it should be replaced by external circulation every hour to let the air inside the car convection.

Therefore, the external circulation is to ventilate the car, so that the dirty and oxygen-deficient air in the car can be discharged and flow into the fresh air. Then what is our internal circulation for?

it has two functions, one is to turn off the external circulation to prevent bad air from entering the car, and the other is to keep the temperature inside the car. Generally, there are several kinds of environments that are best to open internal circulation, such as underground garage, traffic jam and sandstorm, to prevent automobile exhaust, dirty air in underground garage and sandstorm dust from entering the car.

But we always use car air conditioners in winter and summer. How should we cooperate to use internal circulation and external circulation?

As we just said, internal circulation can keep warm, keep warm in winter and keep cool in summer. Therefore, in general, whether it is warm air or cold air, we start the internal circulation first. However, with the continuous internal circulation, although the temperature inside the car drops, the dioxide exhaled by people inside the car will increase. Therefore, it is best to switch to the external circulation every hour to change the air.

We have seen some news about suffocation in the car before. Many times, it was because the internal circulation was always on. After parking, we slept in the car, locked ourselves in a completely closed small space, and there was no fresh air flowing in, and finally died of suffocation.

finally, to sum up for everyone, generally, when we turn on the air conditioner, refrigeration or warm air, we can turn on the internal circulation first, and quickly let the temperature in the car drop or rise; When the temperature is stable, switch to the external circulation properly and exchange air with the outside of the car;

however, if the air environment outside the car is not very good, such as a lot of exhaust gas in traffic jams and bad air in the basement, don't circulate outside. If you are running at a high speed, don't open the window, just open the external circulation. In short, in a word, when the air outside the car is good and you feel stuffy inside the car, you should quickly open the external circulation for air exchange; If you want to stay in the car, turn on the internal circulation.

I believe everyone has seen cars smoke, but do you know why cars smoke? What harm will black smoke do to cars? What is its solution?

1: because the oil supply of each cylinder of the high-pressure oil pump is uneven or too large. Uneven oil supply will lead to unstable rotating speed and intermittent black smoke, which should be adjusted to make it balanced or within the specified range.

2: the diesel itself. The brand of diesel oil used is wrong, the viscosity is too high, or the quality of diesel oil is too poor to catch fire, which makes the exhaust gas emit black smoke, and at the same time, the combustion chamber and exhaust pipe are easy to produce carbon deposit. The solution: choose appropriate regular diesel oil.

3: The fuel injector works badly or is damaged, resulting in insufficient diesel atomization.

The main reasons are as follows:

(1) The injector pressure is too low;

(2) the pressure regulating spring of the injector is broken or hairpin;

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(3) The needle valve of the fuel injector is stuck or worn excessively due to carbon deposit on the valve seat;

(4) The decompression annulus of the oil outlet valve of the fuel injection pump is excessively worn, which makes the fuel injector drip. Solution: It is better to disassemble and clean the fuel injector or directly replace it.

4: The gap between the intake valve and the exhaust valve is too large, which reduces the valve opening, or the parts of the accessory mechanism are loose, worn and deformed, and the relative position of the camshaft gear and the crankshaft timing gear changes, and the valve opening and closing time is incorrect, resulting in insufficient fresh air in the cylinder. Solution: Check the valve clearance, valve spring and valve seal

5: The exhaust back pressure is too high or the exhaust pipe is blocked. This situation will cause insufficient air intake, thus affecting the air-fuel mixing ratio and causing excessive oil. Solutions: First, there are too many bends in the exhaust pipe, which should be reduced as much as possible; Second, the muffler is blocked by too much soot and should be removed.

6: The plunger coupling of the fuel injection pump is seriously worn, which makes the fuel supply pressure of the pump rise slowly, thus affecting the normal fuel supply time, prolonging the fuel injection process and affecting the quality of fuel injection atomization, which is a common fault of black smoke emitted from diesel engine exhaust. Solution: The oil pump should be replaced and repaired in time.

7: insufficient air intake or blocked air intake pipe. In order to find out the reason, the following inspections should be carried out: First, whether the air filter is blocked; Second, whether the intake pipe leaks air (if there is such a phenomenon, the engine will be accompanied by a harsh whistling sound due to the increase of load); The third is whether the turbocharger is damaged. Solution: check whether the blades of waste gas wheel and booster wheel are damaged and whether the rotation is smooth and flexible; The fourth is whether the intercooler is blocked.

8: The cylinder liner and piston assembly are seriously worn. When this happens, the piston ring is not tightly sealed, and the air pressure in the cylinder is seriously reduced, which leads to the diesel oil not being fully burned and emitting black smoke, and the engine power is drastically reduced. In serious cases, the engine will automatically turn off when it is loaded. Solution: Wear parts should be replaced.

the phenomenon of black smoke will cause great damage to the engine, so everyone must repair it in time after discovering it! That's all, I hope you like it! !