There is one interesting thing. Rider Xi Ti drove a new car, after driving on the highway for several hours, stopped in the service area to turn off the engine, passed the front of the car, felt the heat wave, reached out and touched the hood, felt that the hand should be very hot, the time passed, the engine temperature was too high, the hood This practice seems to be no problem, but such behavior is always "ridiculed" by the old driver, is it necessary in the end? See what the repairman has to say. In fact, the engine is heat-resistant, in the car driving, the temperature when the cylinder is burning reaches more than 2000, the temperature of the cylinder wall is also about several hundred, and the various components of the engine work at such high temperatures for a long time, so it is easy to have problems. However, our concern is that automotive engineers are thinking about the engine cooling system during the engine development phase. Today's family cars generally use "forced circulating water cooling system", which can dynamically balance the heat generated by the engine and heat dissipation. Its temperature is usually maintained at 80 to 100, which is the temperature required for the engine to work properly.
The water cooling system mainly relies on special coolant to absorb the heat generated by the engine, and the high temperature coolant is cooled by the cooling fan, and then flows through the engine again, continuously dissipating heat, so that the cycle repeats the engine to maintain "constant temperature". When the engine is running, the driving computer adjusts it in real time according to the vehicle speed, engine temperature, coolant temperature, etc. For example, when the car first starts, the engine temperature is very low, the thermostat will not open, and the cycle will not begin after the engine and coolant temperature gradually rise. When the vehicle is driving at high speeds, if the engine speed is high, the cooling system will work at full efficiency. Engines have a variety of ways to dissipate heat, on the contrary, if you run a high-speed engine, the heat dissipation is better. First of all, on the highway, the speed is very fast. In the average family car, the speed is 100km/ h, and the engine speed is only about 2000 rpm at this time. At this time, low speed, high load, high thermal efficiency, this is the ideal working condition of the engine, the heat generated is relatively small.
Secondly, the engine can dissipate heat through the front grille, oil, fan, natural heat dissipation and other ways. The intake grille can not only provide air to the engine, but also play a role in heat dissipation of the engine. On the highway, the speed is fast, the air volume through the intake grille is also increased, and the heat dissipation effect is obvious. Compared to opening the lid to dissipate heat, another problem is worth paying attention to. After the vehicle has been driving for a long time, as soon as it stops, it will immediately turn off the ignition, and it is customary to lock the car and go out. After the engine is stopped, the oil begins to flow counter-, the cooling system stops, and the coolant dissipates insufficient heat. At this time, the engine instead collects a lot of heat in a short period of time. So, every time the engine is turned off, you can hear that the fan is still spinning. At this time, heat can only be dissipated by the fan. That is to say, instead of opening the lid to dissipate heat, it is better to let the engine idle for a period of time after stopping, but the cooling effect is better. Five notes about the engine:
1. The engine has just started, do I need to preheat and then drive? In the past, I heard some old drivers say that the vehicle has just started, don't rush to drive, and warm up after idling. The reason for this is that the engine temperature is low, it does not reach the temperature when working, the oil is in the oil pan, there is no lubrication effect, and it is not good for the engine. In fact, today's engines are no longer the era of carburetors more than 20 years ago. No long warm-up is required. Usually, when starting the engine, the engine is loud and the speed is high. After waiting a few seconds, the speed returns to normal and you can drive at this time. However, the engine has just started and there is no need to preheat the engine deliberately, but do not press the accelerator or drive at high speeds at this time. At this time, because there is no oil flow of the engine components as a whole, if the engine parts run at high speeds, the wear between the engine components will increase, and the engine life may be reduced for a long time. Black smoke may appear immediately after start-up. This is the engine temperature is low, the combustion is not sufficient. Therefore, after a low-speed driving distance, the temperature of the engine gradually rises from 80 to 100 before the vehicle can work properly. On the contrary, long-term idling hot car, engine speed, power reduction, combustion chamber gasoline mixture can not be fully burned, its residue attached to the valve, cylinder wall, piston surface, long time gradually carbon deposition, long time idle,
2. How much engine coolant is added? In general, most of them are aqueous glycol antifreeze, which is replaced every 2-4 years or 3-60,000 kg. The anhydrous type is a long-lasting antifreeze, which is generally replaced once in more than 5 years and does not need to be replaced. It is only necessary to confirm how much antifreeze remains during the period, and if the residual antifreeze is below the labeled minimum, it should be added. Antifreeze must be added to make it the same color as the original. Antifreeze comes in different colors, generally common pink. In addition, there are green, brown and so on. Do not add too much. Do not exceed the maximum level value. If the antifreeze has not been replaced for several years, the balance is still large, but it is also necessary to pay attention to prevent expiration and smell. Smelling fishy needs to be replaced, and it is also possible to measure below freezing point. Minus 35 or so is normal, it is necessary to pay attention here, you need to confirm the antifreeze in the cold state of the vehicle. The change interval of antifreeze varies depending on the model and type. For example, most of Mercedes-Benz models use long-term antifreeze from the factory. Officially, it is replaced every 10 years or 250,000 kilometers. In addition, the Hofdo model, for example, requires replacement every two years or 40,000 kilometers. The specific replacement cycle can refer to the requirements of the manufacturer.
3. Can antifreeze be replaced with water? A few years ago the cooling of the engine relied on water, but with the advancement of technology, antifreeze is now used. It is a special liquid for mixing, and its functions are many, such as the freezing point of the antifreeze of more than 40, which can prevent freezing in low temperature environments. Antifreeze contains ethylene glycol, the boiling point at high temperature is much higher than water, while there are antioxidant, anti-corrosion and other effects, its effect is much higher than ordinary water. Therefore, it is generally not recommended to replace it with water. 4. What is the harm to the engine due to insufficient coolant? If there is little or no coolant, the engine water cooling system will not work properly and will not be able to play a cooling role. With the extension of the engine working time, the temperature gradually increases, with the increase of oil temperature, the lubrication performance is reduced, the piston, crankshaft and other components are damaged, and problems such as tire bursts, brake pads, locking shafts, and cylinder pulling may occur. In this case, it is basically necessary to overhaul the engine.
5. The engine compression ratio and design requirements of different models of mixed gasoline are different, and different symbols of gasoline need to be used. The aim is to reduce the knocking of the engine. There are also owners who do not comply with the manufacturer's requirements. For example, No. 95 gasoline was originally added, but in order to save money, No. 92 gasoline was added. Although this situation does not see any effect for a short period of time. However, for a long time, if you pay attention to it, the engine sound becomes louder, the sense of oscillation will also increase, in the long run, the carbon accumulation of the engine will increase when the condition is serious, the ternary catalyst, oxygen sensor, etc. will fail, the power will become weaker, or damage the engine components, so please do not mix different numbers of gasoline. If the manufacturer assigns to refuel No. 92 gasoline, it is usually possible to refuel No. 95 gasoline. In different brands of gas stations, it is possible to mix gas stations of the same number to refuel. For example, PetroChina 95 gasoline and Sinopec 95 gasoline can be mixed with refueling.
6. How many kilometers can the vehicle continue to travel without resting? This mainly depends on the durability of the vehicle and the stability of the vehicle. New cars usually undergo rigorous durability and reliability tests before mass production. General vehicles will undergo road tests of more than 600,000 kilometers and durability tests of more than 2 million kilometers. In bench testing, the general engine runs continuously for more than 1000 hours. In other words, the engine is not so squeamish, and in the case of normal maintenance, it is no problem to continue to travel tens of thousands of kilometers without turning off. In short, the engine does not need to open the cylinder head to dissipate heat, in daily operation, according to the workshop manual for corresponding maintenance.