When we go to the repair shop to repair the car, we often see that some engines are repaired. The reason why these engines repairing these engines are nothing more than “pulling the cylinder”, “turning the tile”, “burst cylinder”, “top cylinder”, “severe burning oil” and so on. For these auto repair Xiaobai, these words are tantamount to the “black words” of Yang Zirong. Today, Lao Hou uses as straightforward language as possible to tell you what these words mean. Let’s take a look at where the “pulling cylinder” pulls? What is the “explosive cylinder” burst? How did the “top tank” top? How can we avoid these faults in daily use.
To explain this problem, we must first briefly introduce the relevant knowledge of a car engine. The engine used on the car is the full name is “four -stroke water cooling to the rehabilitation engine”. The piston moves in the middle and downward movement in the cylinder, completes the four strokes of intake, compression, work, and exhaust. , Drive the crankshaft rotation and output the power outward. In the process, a “happy enemy” played a vital role: Pistons-cylinder. They are also the largest sporting friction in the engine and are the core institutions of the engine.
Let’s talk about the piston first. The piston is a cylindrical body that moves in the middle of the engine cylinder. It forms a combustion chamber with the cylinder head and the cylinder wall. The fuel is burned in it. The crankshaft drives the crankshaft rotation. The working environment of the piston is extremely harsh. The top is directly in contact with the high temperature, high pressure, and corrosive gas. It has the role of huge gas pressure and inertial force. Specifies between the piston surface and the cylinder wall during high -speed exercise. Therefore, the piston must have sufficient strength and stiffness, and has the performance of abrasion and high temperature resistance. The smaller the quality, the better.
Pistons are usually cast with silicon aluminum alloy, and some high -enhanced diesel engines are made of advanced cast iron or heat -resistant steel. Pistons are divided into three parts: top, head and skirt. The top and the cylinder head and cylinder wall constitute the burning room. Its shape determines the shape of the burning room and is an important factor affecting the combustion state; the head is used to install the piston ring. The heat is passed to the cylinder wall; the skirt is mainly guided by the piston movement, and the side pressure of the cylinder wall is applied to the piston. The current household gasoline engine usually uses a trailer piston skirt. The piston is on the shape of the small lower and big cone. The upper part is heated more at work, and the expansion is greater, which becomes similar to circular.
The piston will be deformed by heating and expansion at work, but its deformation is not uniform. The top of the piston will bend and deformed under the action of gas pressure. Under the action of side pressure, there will be deformation along the direction of the piston -selling axis. There will be more metals at the piston sales hole. The lower part of the heating is less deformed. The oval deformation of the piston will destroy the cooperation with the cylinder wall and make the engine work abnormal. Therefore, the piston will also take some insulation and compensation measures in the structure, such as opening insulation tanks, expansion grooves, elliptical conical skirts, and inlaying constant steel sheets in the piston.
In addition, strengthening the cooling and lubrication of the piston is also very important. Some high -enhanced engines have special oil nozzles to cool down the piston spray oil and cool down. Use the oil ring to lay oil on the wall of the cylinder , Or apply graphite, spray polytetrafluoroethylene coating, etc., to improve the abrasion resistance and high temperature resistance of the piston.
Let’s talk about the engine cylinder. The cylinder is a cylindrical cavity that guides the upper and lower movements in the engine. It is also part of the combustion room. It must withstand huge gas pressure and high temperature, corrosion, etc., so it requires it to have sufficient strength, heat resistance, wear resistance. In order to save materials, reduce costs, and ensure the service life of the engine, in most engines, it is inlaid into a cylinder sleeve in the cylinder to form a cylinder working surface.
The cylinder sleeve is made of alloy cast iron or alloy steel with good thermal resistance. The cylinder body is cast with cheaper ordinary cast iron or aluminum alloy. When the cylinder sleeve is over -wear, it can also be repaired or replaced separately, which can reduce the cost of use and maintenance. Some aluminum alloy engines are not inlaid with cylinder sets, but instead of electrochemical processing on the cylinder wall. In addition, processing the inner wall of the cylinder cover into a grid shape can form a tiny oil storage pool to enhance the lubrication of the piston.
The cylinder sleeve is fixed. The piston moves in the middle and downward movement in the cylinder sleeve. A normal household gasoline engine, assuming that the piston itinerary is 87mm, when the engine runs in 2000 rpm, the relative speed of the two is nearly 6 meters/s. With such a high friction speed, if there is no good lubrication and heat dissipation, the friction will soon be destroyed, so the lubrication and heat dissipation of the Pistons-cylinder is the core technology of the engine. In addition, due to the existence of side pressure and gas pressure, the piston is not running in the middle of the cylinder, but is biased towards one side at the time of up and down. The engine is inevitable.
There is a gap between 0.05 ~ 0.1mm between the piston and the cylinder sleeve. This gap is called “matching cylinder gap”. The numerical value of different engines is slightly different. Generally, the cast iron cylinder is slightly larger than the aluminum alloy piston, and the aluminum alloy cylinder is slightly smaller than the aluminum alloy piston. Such a small coordination gap requires precise mechanical processing technology and equipment to achieve. We usually say that the engine production is precise, which mainly refers to this part. In addition, the thermal expansion of the metal is also a factors that must be considered. Different metal materials are used. The thermal expansion coefficient is different and the gap between the cylinder is also different. These are the core technologies of the engine.
It should be noted that this parameter is the data during the cold car, and the gap between the piston skirt and the cylinder wall. When the engine reaches normal operating temperature, this gap will narrow to about 0.02 ~ 0.05mm. If this gap is too large due to wear, the sealing performance of the piston-cylinder will decrease significantly, the pressure of the cylinder is reduced, the combustible mixed gas entered the combustion room is insufficient, it is difficult to burn, and the gap between the piston-cylinder wall is leaked to form formed The so -called “lower exhaust”, the power of the engine has decreased, and the oil consumption increases dramatically. In this case, the engine needs to be repaired.
Knowing the characteristics of the piston, the characteristics of the cylinder, and the movement of the two, you can explain the terms such as pulling and explosive cylinder.
As mentioned earlier, the gap between the piston-cylinder is very small. If there are hard particles entering this gap, under the action of high -speed movements and huge inertia of the piston, it will cause scratching the cylinder wall and the piston surface. Pull the cylinder. Therefore, simply speaking, “pulling the cylinder” is the vertical scratching of the inside surface of the cylinder wall. The cause of pulling the cylinder generally has impurities into the combustion room, such as the carbon pellets that fall off, the hard particulate matter in the air, etc. In addition It can cause a tank failure.
When the engine fails to pull the cylinder, because the sealing of the cylinder decreases due to the leakage of the scratching area, the opportunity to mobilize abnormal sounds, jitter and other phenomena, the engine power decreases, and the lower exhaust increases. A one will be seen at the oil ruler. The wicked smoke came out of this. If it is a slight pull cylinder, the engine can continue to be used, just avoid large load operation. If it is a severe pull cylinder, it must be stopped for repair. An important measure to avoid tank failure is to use good quality air filters and maintain a good sealing of the air intake pipeline. middle. In addition, reducing the accumulation of carbon in the engine burning room is also one of the measures to avoid pulling the cylinder.
So what is the “explosive cylinder”? Everyone heard it, exploded, wow, the engine exploded!
Actually not. The current car engine is very safe and will never explode. The so -called “explosive cylinder” actually refers to the failure of the dying and the cylinder sleeve card.
As mentioned earlier, when the engine works normally, the gap between the piston and the cylinder wall is very small. But this is built in the case of good engine heat dissipation. If the engine heat dissipation is not good, or when the load work for a long time, the temperature of the piston will rise sharply, the expansion and deformation of the cylinder will not be large, so the gap between the piston and the cylinder case will disappear. The two from the time of the gap became a transmission. Under the influence of the flywheel inertial force, the piston still maintains a recurring movement, and severe friction occurs between the wall of the cylinder, which generates a lot of heat, so that the piston shows the melting with the metal surface of the inside of the cylinder wall, melts together, and then tears again. Essence At this time, the surface of the piston and the cylinder sleeve was completely damaged, and the friction pair was completely damaged. As a result, huge resistance forced the engine to stop running. The high temperature made the piston melt with the cylinder sleeve, and the engine could not work at all.
The explosive cylinder is generally caused by the high temperature of the engine. At this time, the cooling liquid in the engine will boil, and the smoke in the engine compartment is like an explosion, so it is called a “explosive cylinder”. The explosive cylinder is a serious mechanical failure. The piston and the cylinder sleeve in the engine can not die. They completely lose their ability to work. They must be disassembled to repair them. If the car occurs in a high -speed driving, it will even cause the car to get out of control, which is one of the very dangerous engine failures. Therefore, in daily use, we must maintain a good heat dissipation capacity of the engine. If the engine temperature is too high, we must stop checking, and we must not run with illness.
Let’s talk about how the engine “top cylinder” tops. There are two cases of the top tank of the engine, one is the top of the piston and the valve, and the other is the piston top or other foreign objects.
When the engine is working, the piston moves up and down. When the piston reaches the upper end point, or the exhaust end, or the compression end. If it is the end of the exhaust, at this time, the intake valve is opened, and the valve is stacked. At this time, the gap between the valve and the piston top is less than one millimeter. In addition, while the piston movement is moved up and down, the valve is also opened or closed, and the two maintain a specific exercise relationship and ensure that the two will not interfere with exercise.
This specific motion relationship is completed by the engine gas distribution mechanism. If the gas distribution mechanism fails, such as the timing belt breaks, the timing chain jumping teeth, the camshaft break, etc., the valve no longer moves with the piston, but keeps it in a certain position. It will be broken. When the piston movement is up to the upper stop point, the top of the piston at high -speed movement collides with the open valve, crushing or rupture of the piston, the valve breaks or bending, and even a broken cylinder head and cylinder will even be damaged. The engine is completely damaged. If the car occurs at a top cylinder during a high -speed driving, the car will instantly lose power, the engine is damaged or stuck, and the car will easily get out of control.
The vast majority of the top tank of the top air -type type is caused by the time -time belt or the timing chain that is not replaced in time. Therefore, we must replace the timing belt or timing chain on time according to the requirements of the maintenance manual. Don’t listen to the lies of some old drivers: don’t change if you look good. The consequences of the top tank are extremely serious. The engine is basically completely scrapped, and it takes only a few hundred dollars to change a belt.
Another type of top tank is the piston to water or other foreign objects.
During the engine work, during the compressor, the top of the piston is compressed by combustible mixed gas. Gas can be compressed and can be compressed into a small group. However, if the engine is wading, water instead of air in the cylinder in the cylinder in the airbuilding process, then the piston is compressed during the compressed process, and the water cannot be compressed. If we forcibly mobilize the car, the piston is forced to rise under the driving of the starting motivation. When we encounter water closed in the cylinder, we will be blocked by water and cannot rise. At this time, the starting motivation continues to rotate the crankshaft, and the connecting rod continues to promote the upward of the piston. Under the huge resistance, the connecting rod will bend and deform, and the valve will also bend due to the collision of water. Essence If water is replaced with other non -compressed foreign bodies, such as screws, spark plugs, etc., the consequences are the same. Therefore, the engine must not be started after the wading.
The top cylinder mentioned above, if the consequences are very serious, it will cause piston link to break. The connecting rod swing at high speed in the engine will break the cylinder body, which causes another serious failure: pounding the cylinder. After the tank is pounded, the engine shell is completely ruptured. The internal components are basically deformation and damaged, and the engine is completely scrapped.
Finally, let’s summarize: The engine pulling cylinder refers to the entering impurities between the piston and the cylinder sleeve, and a vertical groove pattern is formed on the cylinder cover. This situation only needs to replace the damaged piston and the cylinder alone; The piston and cylinder are killed. In this case, the “four supporting facilities” of the engine need In the later period, it is prone to failure of oil leakage, water leakage, and cylinder pads; while the very serious mechanical accident in the top cylinder, the engine of the top cylinder has no maintenance value. Generally, the engine assembly needs to be replaced or the mid -cylinder is replaced.