Throttle cognition

Six pieces of automobile knowledge break your inherent cognition

Many system functions or car parts can be recognized only by their appearance, and we can easily tell their functions. But the reality is so interesting. There are many things in the car, and their actual working principles or ways are really different from what we imagined. Some you think are simple, but in fact they are complicated. And some things that you think are very tall are actually not as high-end as you think. Today we will talk about some knowledge about cars that may break your inherent cognition.

1, the generator is connected to the engine and has been generating electricity. There is no need to use it in vain.

Many people think that the generator is directly connected to the engine, and it has been generating electricity. If it is not used, it is a waste of electricity, so I can't wait to turn on all the lights when driving at night.

In fact, the more lights you turn on, the higher the fuel consumption will be, because the car generator is not always busy generating electricity as you think. It is very intelligent and will automatically adjust the power generation.

There is a coil in the generator, which is called the excitation coil. Its function is to generate a magnetic field after being electrified to replace the magnet in the generator. The regulator of the generator controls the magnetic force by controlling the current of the excitation coil, so as to adjust the power generation. When the demand for automobile electricity is large, the excitation current will be large, the power generation of generators will also increase, the difficulty of driving generators by engines will increase, and the fuel consumption will naturally increase.

2. Where does the front cooling fan blow air?

There is a radiator in the front of the car, and there will be one or two fans behind the radiator. Many people take it for granted that the coolant flows through the radiator, and then the fan blows against the radiator to cool the coolant. In fact, this fan does not blow air at the radiator, but draws air into the engine compartment, sucks the air in front of the radiator and takes away the heat when passing through the radiator. In fact, blowing against the radiator is the hot air in the engine compartment, and the heat dissipation effect will definitely become worse.

Moreover, the airflow from the front of the car is very strong, and the fan can't fight against the strong airflow at all. However, the air sucked in by the fan is different. When driving at a low speed or parking in place, you can use the air with lower temperature outside the car to dissipate heat. When driving at medium and high speed, the fan hardly needs to work, and the cooling demand can be met only by the airflow flowing at high speed in the front of the car.

3. Is the water pipe on the throttle radiating?

If you have cleaned the throttle yourself, you will find that there are many black pipes on the throttle that communicate with the cooling system, and there is coolant flowing inside. We will take it for granted that this is to cool the throttle.

Actually, it is not, because the throttle itself does not generate heat, and it is installed on the intake manifold, far away from the high temperature area of the engine. It is reasonable to say that there is no cooling requirement. Then why put so many radiator tubes in it?

In fact, these water pipes are used to heat the throttle, because the air will flow through the throttle continuously when the engine is working, thus cooling the throttle. Especially in winter, when the water vapor in the air passes through the throttle, it may liquefy to produce water droplets, and the cold air will continue to flow through the throttle, which may freeze the water and the throttle. Even if you loosen the throttle engine, it will not reduce the horsepower, which is very dangerous. Therefore, it is necessary to guide the high-temperature coolant to the throttle to ensure that it does not freeze. In addition, some old engines also need to control the idle valve through the coolant temperature to adjust the idle compensation.

The fuel tank cover is actually a one-way valve.

Many people will tighten the tank cover after filling it with oil, for fear that the seal will not be good and the oil will leak again. In fact, you may not know that the fuel tank cover has not completely sealed the fuel filler. It is equivalent to a one-way valve to prevent gasoline and gasoline vapor from escaping from the fuel tank, but outside air can enter the fuel tank through the fuel tank cover.

Why do you want to design like this?

The car will consume gasoline continuously when driving, and the fuel tank is completely sealed. With less and less gasoline, a vacuum will gradually form in the fuel tank, which will not only affect the oil absorption of the oil pump, but also cause the fuel tank to be sucked flat. Therefore, the fuel tank cover should be designed to conduct electricity in one direction. When a part of gasoline is consumed and the negative pressure of the fuel tank reaches a certain level, the valve on the fuel tank cover will be sucked open, which can replenish the outside air and prevent the vacuum degree of the fuel tank from being too high.

5, the maximum torque speed may not really output the maximum torque.

Xiaoming just bought a car. After checking the parameters, the engine can output the maximum torque at 5000 rpm. Then Xiao Ming wanted to drive on the road to experience it, so he stepped on the speed of 5000 rpm excitedly. As a result, when the speed reached 5000 rpm, the expected feeling of pushing back did not come, and Xiao Ming did not understand it.

Why has Xiao Ming stepped on the engine at the maximum torque speed, and the power has not changed much? The answer is actually very simple: Xiao Ming didn't step on the accelerator to the end! Because the maximum torque in the engine parameters is measured when the accelerator pedal is fully depressed, you must fully depress the accelerator pedal to feel the maximum torque of the engine during driving.

6. Is the exhaust gas from the engine pushed out by the piston?

We learned the basic working principle of the engine in junior high school physics class, knowing that the intake stroke piston sucks air and gasoline into the cylinder, and the exhaust stroke piston pushes the burnt exhaust gas out of the exhaust pipe.

In reality, part of the exhaust gas is not pushed out by the piston, but runs out of the cylinder by itself. Because when doing work, the mixed gas burns and expands violently, pushing the piston to move downward. When the piston moves to the bottom, that is, the bottom dead center, the mixture in the cylinder still has a certain pressure. At this point, the exhaust stroke starts, the piston starts to move upward, and at the same time, the exhaust valve opens. At this time, a part of high temperature and high pressure exhaust gas will automatically rush out of the exhaust valve, and the pressure in the cylinder will drop rapidly. Then the piston moves upward to push the remaining exhaust gas out of the cylinder.

It is precisely because some exhaust gas is automatically discharged under pressure when the exhaust valve is opened that the exhaust sound of the engine is so loud, especially after the exhaust pipe of some cars is broken, the exhaust sound is as loud as firecrackers. It is precisely because there is still a certain pressure in the cylinder after the piston reaches the bottom dead center, so the current engine generally adopts the design of small cylinder diameter and large stroke, because the piston moves downward for a longer distance, which can give full play to the expansion energy of the mixture, thus improving the thermal efficiency.

In the past, some engines paid more attention to power and power, and liked to use the design of large cylinder diameter and small stroke. Therefore, these engines have higher speed, higher power and better exhaust sound when accelerating, but the disadvantages are high fuel consumption and low thermal efficiency.

Do you feel that you have learned anything when you see this place? This is the case with cars. Many functions and systems are constantly improved in the long-term application. People's needs and various legal requirements are promoting the development of automobile technology. In the future, there will be more new and exotic technologies in front of us.