1. residual impurities in the production process

生產過程中，在鍛、鑄件的非加工面上未處理干凈的型砂和氧化皮。如缸體、缸蓋、進、排氣歧管、曲軸及凸輪軸等鑄、鍛件非加工面殘留物及機加工后留下的切屑、毛刺等。裝配前若這些雜質不清理干凈，都將影響件的清潔度。未清理干凈的雜質，在發動機運轉過程中，受到振抖和潤滑油沖刷落于機油盤中，再被帶入到各摩擦表面;有些直接進入摩擦面，如殘存在機械、曲軸油道中的切屑、毛刺以及型砂等，這將形成磨料，加速磨損、降低發動機的耐久性與使用壽命。

During the production process, no clean sand and oxide skin were disposed on the non machined surface of forging and casting. Such as cylinder block, cylinder head, intake and exhaust manifold, crankshaft and camshaft casting, forging non-machined surface residues and chips and burrs left after machining. If the impurities are not cleaned before assembly, the cleanliness of the parts will be affected. Uncleaned impurities, in the process of engine operation, are flushed into the oil pan by shaking and lubricating oil, and then brought into the friction surface; some directly enter the friction surface, such as residual chips, burrs and moulding sand in the crankshaft oil duct, which will form abrasives, accelerate wear and reduce engine resistance. Durability and service life.

2.裝配過程中的污染

2. contamination during assembly process

裝配過程中，部件的污染將直接影響發動機的裝配質量與耐久性。配件的污染程度與裝配場地的凈化程度和維修人員的責任心有關。場地的凈化程度，一般由控制日降塵量來控制。國外的日降塵量控制在5mgm2;而較好的是50mgm2左右，大多數場地衛生條件差。維修人員責任心不強，對清潔度認識不足，維修工具粘滿泥沙、用臟抹布擦件等，嚴重地影響裝配質量。普遍存在大修、維護后故障率較高，使用壽命縮短的現象。

During the assembly process, the contamination of components will directly affect the assembly quality and durability of the engine. The degree of contamination of the fittings is related to the cleanliness of the assembly site and the sense of responsibility of the maintenance staff. The cleanliness of the site is usually controlled by the amount of dustfall. The daily dustfall is controlled at 5mgm2, while the best is 50mgm2. Most of the sites have poor hygienic conditions. Maintenance personnel have a weak sense of responsibility, lack of awareness of cleanliness, and maintenance tools are filled with sand, and dirty wipes are used to wipe parts, which seriously affect the assembly quality. Generally there is a high failure rate and short service life after overhaul and maintenance.

3.油料中的污染雜質

3. contaminants in oil

車用燃料中，技術規定不允許含有機械雜質。但是燃料在運輸、保管和使用過程中，都可能混入無機的和有機的雜質。有隨空氣進入，也有燃油箱真空吸入。一般夏季比冬季高20%-70%，與使用季節及道路條件都有關系。燃油中的有機污垢雜質，主要是其中的不穩定成分不斷氧化，聚合成一種膠狀產物。這些無機和有機的雜質不僅易堵塞油路，而且小于50μm的灰塵微粒都能通過供油系的濾網進入氣缸，使氣缸與活塞發生磨料磨損。同時還會增加化油器量孔、加速泵的磨損，或增加柴油機供油系中精密偶件的磨損。

In vehicle fuel, technical regulations do not allow mechanical impurities. However, in the process of transportation, storage and use, fuel may be mixed with inorganic and organic impurities. With air entering, there is also a vacuum suction from the fuel tank. Generally, summer is 20%-70% higher than winter, which is related to season and road condition. Organic fouling impurities in fuel oil mainly consist of unstable components which are oxidized continuously to form a gelatinous product. These inorganic and organic impurities are not only easy to plug the oil circuit, but also dust particles less than 50 microns can enter the cylinder through the oil supply system filter, making the cylinder and piston abrasive wear. At the same time, it can increase the wear of carburetor measuring holes, accelerator pumps, or the wear of precision couples in diesel fuel supply system.

潤滑油中的污垢物可以分成有機污垢和無機污垢，為熱分解氧化和聚合產物，這些雜質起著磨料磨損的作用，加速了件磨損，降低件的抗磨性能。現代汽車發動機潤滑油中，污垢雜質的濃度一般不超過0.4%-0.6%，柴油機不超過1.0%-1.2%，潤滑油工作壽命一般為3000-6000km。

The dirt in lubricating oil can be divided into organic dirt and inorganic dirt, which are products of thermal decomposition, oxidation and polymerization. These impurities play the role of abrasive wear, accelerate the wear of parts and reduce the wear resistance of parts. In the lubricating oil of modern automobile engine, the concentration of dirt and impurities generally does not exceed 0.4%-0.6%, the diesel engine does not exceed 1.0%-1.2%, and the working life of lubricating oil is generally 3000-6000 km.

4.空氣中的灰塵雜質

4. dust impurities in the air

灰塵微粒的基本成分是二氧化硅(SiO2)占65%-95%，其余為三氧化二鋁或氧化鐵，以及少量的鈣、鎂、鈉和其它元素的化合物。一般公路上的含塵量為0.001gm3，土路上的含塵量為0.40-0.45gm3。大城市空氣含塵量為0.00025-0.0084gm3，73.55kW發動機每小時約消耗4000m3的空氣。當運行在良好的公路上時，發動機工作10h將吸入4g灰塵。因此汽車長期在灰塵中行駛，磨料磨損成其主要磨損方式。

The basic composition of dust particles is silica (SiO 2) accounting for 65% - 95%, the rest is aluminium oxide or iron oxide, and a small amount of calcium, magnesium, sodium and other elements of the compounds. The dust content on the general highway is 0.001gm3 and the dust content on the dirt road is 0.40-0.45gm3. The air in large cities is 0.00025-0.0084gm3 and 73.55kW engines consume about 4000m3 of air per hour. When running on a good road, the engine work 10h will inhale 4G dust. As a result, the automobile has been running in the dust for a long time, and abrasive wear has become the main wear mode.

5.冷卻系中的污垢

5. dirt in cooling system

冷卻系中污垢較多時，對發動機的冷卻會產生極不利的影響。綜上所述，對汽車維修行業及有車用戶來說，維修場地及行車環境的清潔度水平，直接影響汽車發動機的使用壽命。那么應從以下幾個方面予以注意：

When the fouling in the cooling system is more, the cooling of the engine will have a very negative effect. To sum up, for the automobile maintenance industry and users, the cleanliness level of the maintenance site and driving environment directly affects the service life of automobile engines. We should pay attention to the following aspects:

1)。發動機裝配時場地的清潔度。

1). Cleanliness of the site during engine assembly.

2)。磨合時潤滑油、燃料的清潔度。

2). Cleanliness of lubricating oil and fuel when running in.

3)。長期停放車輛的“三濾”及通氣口應封閉。

3). The "three filters" and ventilation ports for long-term parking should be closed.

4)。車輛行駛中，進氣過濾的清潔度問題。

4). The cleanliness of air intake filtration during vehicle running.