1. residual impurities in the production process

生产过程中，在锻、铸件的非加工面上未处理干净的型砂和氧化皮。如缸体、缸盖、进、排气歧管、曲轴及凸轮轴等铸、锻件非加工面残留物及机加工后留下的切屑、毛刺等。装配前若这些杂质不清理干净，都将影响件的清洁度。未清理干净的杂质，在发动机运转过程中，受到振抖和润滑油冲刷落于机油盘中，再被带入到各摩擦表面;有些直接进入摩擦面，如残存在机械、曲轴油道中的切屑、毛刺以及型砂等，这将形成磨料，加速磨损、降低发动机的耐久性与使用寿命。

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.装配过程中的污染

2. contamination during assembly process

装配过程中，部件的污染将直接影响发动机的装配质量与耐久性。配件的污染程度与装配场地的净化程度和维修人员的责任心有关。场地的净化程度，一般由控制日降尘量来控制。国外的日降尘量控制在5mgm2;而较好的是50mgm2左右，大多数场地卫生条件差。维修人员责任心不强，对清洁度认识不足，维修工具粘满泥沙、用脏抹布擦件等，严重地影响装配质量。普遍存在大修、维护后故障率较高，使用寿命缩短的现象。

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.油料中的污染杂质

3. contaminants in oil

车用燃料中，技术规定不允许含有机械杂质。但是燃料在运输、保管和使用过程中，都可能混入无机的和有机的杂质。有随空气进入，也有燃油箱真空吸入。一般夏季比冬季高20%-70%，与使用季节及道路条件都有关系。燃油中的有机污垢杂质，主要是其中的不稳定成分不断氧化，聚合成一种胶状产物。这些无机和有机的杂质不仅易堵塞油路，而且小于50μm的灰尘微粒都能通过供油系的滤网进入气缸，使气缸与活塞发生磨料磨损。同时还会增加化油器量孔、加速泵的磨损，或增加柴油机供油系中精密偶件的磨损。

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.

润滑油中的污垢物可以分成有机污垢和无机污垢，为热分解氧化和聚合产物，这些杂质起着磨料磨损的作用，加速了件磨损，降低件的抗磨性能。现代汽车发动机润滑油中，污垢杂质的浓度一般不超过0.4%-0.6%，柴油机不超过1.0%-1.2%，润滑油工作寿命一般为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.空气中的灰尘杂质

4. dust impurities in the air

灰尘微粒的基本成分是二氧化硅(SiO2)占65%-95%，其余为三氧化二铝或氧化铁，以及少量的钙、镁、钠和其它元素的化合物。一般公路上的含尘量为0.001gm3，土路上的含尘量为0.40-0.45gm3。大城市空气含尘量为0.00025-0.0084gm3，73.55kW发动机每小时约消耗4000m3的空气。当运行在良好的公路上时，发动机工作10h将吸入4g灰尘。因此汽车长期在灰尘中行驶，磨料磨损成其主要磨损方式。

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.冷却系中的污垢

5. dirt in cooling system

冷却系中污垢较多时，对发动机的冷却会产生极不利的影响。综上所述，对汽车维修行业及有车用户来说，维修场地及行车环境的清洁度水平，直接影响汽车发动机的使用寿命。那么应从以下几个方面予以注意：

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)。发动机装配时场地的清洁度。

1). Cleanliness of the site during engine assembly.

2)。磨合时润滑油、燃料的清洁度。

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

3)。长期停放车辆的“三滤”及通气口应封闭。

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

4)。车辆行驶中，进气过滤的清洁度问题。

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