在维修汽车发动机这么多年，但对于发动机上的很多孔要是不知道是干什么的，下面带你一起去看看这些孔的作用和原理！
I have been repairing the automobile engine for so many years, but if I don't know what many holes on the engine are for, let's take you to see the function and principle of these holes!
曲轴箱上的排气孔
Exhaust hole on crankcase
发动机工作时，一部分可燃气体和废气总会通过活塞环与气缸壁之间的间隙进入曲轴箱。曲轴箱内冷凝的燃油蒸气会稀释机油，废气中的酸性物质和水蒸气会腐蚀零件，使机油性能恶化（稀释、老化和结焦）。
When the engine is working, some combustible gases and exhaust gases always enter the crankcase through the gap between the piston ring and the cylinder wall. The fuel vapor condensed in the crankcase will dilute the engine oil, and the acidic substances and water vapor in the exhaust gas will corrode the parts and deteriorate the performance of the engine oil (dilution, aging and coking).
此外，进入曲轴箱的气体会使箱内温度和压力升高，导致油从油封、垫片等处渗出；由于活塞的往复运动，曲轴箱内的气体压力周期性变化，影响发动机的正常运转，严重时会导致曲轴箱内的机油向上跑到燃烧室和气缸盖罩内。
In addition, the gas entering the crankcase will increase the temperature and pressure in the box, resulting in oil leakage from oil seals, gaskets, etc; Due to the reciprocating motion of the piston, the gas pressure in the crankcase changes periodically, affecting the normal operation of the engine. In serious cases, the oil in the crankcase will run up to the combustion chamber and cylinder head cover.
为了避免上述现象，发动机配备了通风装置，以平衡曲轴箱内外的气压。如果在使用过程中出现烧机油、沿结合面漏油、机油过早变质、发动机怠速运转不稳定等现象，检查曲轴箱通风装置是否有效；确保通风孔通畅，负压阀板不得变形、粘连或安装错误，呼吸管不得弯曲或堵塞，单向阀不得装反，堵头不得用木塞代替。
In order to avoid the above phenomenon, the engine is equipped with ventilation device to balance the air pressure inside and outside the crankcase. In case of oil burning, oil leakage along the joint surface, premature deterioration of oil, unstable idle running of engine and other phenomena during use, check whether the crankcase ventilation device is effective; Ensure that the ventilation hole is unobstructed, the negative pressure valve plate shall not be deformed, adhered or installed incorrectly, the breathing tube shall not be bent or blocked, the one-way valve shall not be installed reversely, and the plug shall not be replaced by a wooden plug.
油箱盖上的排气孔
Vent on tank cap
为防止油箱内的燃油因振动而飞溅、油蒸气逸出和外部灰尘进入，应将油箱盖好并密封。但当因油耗降低油位时，油箱内会形成一定程度的真空，使油泵失去吸油能力；另外，当温度高时，燃油会蒸发，油蒸气会导致油箱内压力过大。
In order to prevent the splashing of fuel oil in the oil tank due to vibration, the escape of oil vapor and the entry of external dust, the oil tank shall be covered and sealed. However, when the oil level is reduced due to oil consumption, a certain degree of vacuum will be formed in the oil tank, resulting in the loss of oil absorption capacity of the oil pump; In addition, when the temperature is high, the fuel will evaporate, and the oil vapor will lead to excessive pressure in the fuel tank.
当罐的内部和外部之间发生压力差时，这两种情况都需要与大气自动连通。为此，在油箱盖上设有通气孔，以平衡油箱内外的气压。使用过程中，确保油箱盖上的通风孔畅通无阻。油箱盖丢失后，如果通风口堵塞或用塑料片堵住油箱，发动机工作时油位下降，油箱内部会形成负压，导致在发动机运行不稳定、功率下降、自动熄火和发动机故障时，在暖机状态等情况下难以启动。
When there is a pressure difference between the inside and outside of the tank, both cases need to be automatically connected to the atmosphere. Therefore, a vent hole is arranged on the oil tank cover to balance the air pressure inside and outside the oil tank. During use, ensure that the ventilation hole on the fuel tank cover is unobstructed. After the fuel tank cover is lost, if the vent is blocked or the fuel tank is blocked with plastic sheet, the oil level will drop when the engine is working, and a negative pressure will be formed inside the fuel tank, which will make it difficult to start under the condition of warm-up in case of unstable engine operation, power decline, automatic flameout and engine failure.
散热器箱上的进排气孔
Air inlet and exhaust holes on radiator box
济南哪里有宝马汽车维修的人员认为发动机工作时，封闭式冷却系统中水温的升高会导致冷却水汽化并产生高压，从而导致散热器芯管因膨胀开裂而泄漏。当发动机负荷降低或停止运转时，冷却系统中的水蒸气会凝结成水，其压力会下降。压力差可能导致芯管被压扁，阻碍冷却水的正常循环。
Jinan where BMW car maintenance personnel believe that when the engine is working, the rise of water temperature in the closed cooling system will lead to the vaporization of cooling water and high pressure, resulting in the leakage of radiator core pipe due to expansion and cracking. When the engine load decreases or stops running, the water vapor in the cooling system will condense into water and its pressure will drop. The pressure difference may cause the core tube to be flattened and hinder the normal circulation of cooling water.
为此，在散热器盖上设置了一个空气蒸汽阀，并有一个与大气相通的公共气孔。当水温升高时，散热器内产生水蒸气，打开蒸汽阀，水蒸气从该孔排出；当水温下降时，压力下降，空气阀打开，外界空气将从这个孔进入散热器，从而保证散热器。内压稳定。在使用过程中，一定要确保这个孔是畅通的，不能被堵塞，否则会影响散热器和发动机的散热性能。
Therefore, an air steam valve is set on the radiator cap, and there is a public air hole connected with the atmosphere. When the water temperature rises, water vapor is generated in the radiator. Open the steam valve and the water vapor is discharged from the hole; When the water temperature drops, the pressure drops, the air valve opens, and the outside air will enter the radiator from this hole, so as to ensure the radiator. The internal pressure is stable. During use, make sure that the hole is unblocked and cannot be blocked, otherwise it will affect the heat dissipation performance of radiator and engine.
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