柴油发动机润滑和冷却系统

二、柴油发动机汽缸润滑

1、气缸润滑的特点和方式

气缸润滑的特殊性首先在于高的工作温度，其次是活塞在往复运动时的速度在中部附近最大，在上、下止点处为零，因此只有在活塞行程中部才有可能实现液体动压润滑。再次是使用劣质的燃油。由于这些原因，气缸套特别是它的上部，很难形成连续完整的油膜，因此一般在气缸套的上部磨损严重。

气缸润滑一般可分为飞溅润滑和气缸注油润滑两种方式。

   （1）飞溅润滑

飞溅润滑靠从连杆大端甩出并飞溅到气缸壁上的滑油来润滑，一般不需要专门的润滑装置，气缸滑油与曲轴箱滑油属同一油品且循环使用，在活塞裙部需装设刮油环以便把飞溅到缸壁的多余滑油刮回曲轴箱。

   （2）气缸注油润滑

气缸注油润滑使用专用的润滑系统及设备，把专用气缸油经缸壁上的注油孔喷注到气缸壁表面进行润滑。目前在十字头式柴油机中均使用此种润滑方式。

三、柴油发动机轴承润滑

轴承润滑按滑油存容场所的不同，润滑系统可分为湿曲轴箱式（简称湿式）和干曲轴箱式（简称干式）两大类。

湿式润滑系统的特点是全部滑油都存容于曲轴箱的油底壳中，油底壳起循环油柜的作用。

干式润滑系统的特点是滑油单独存放在柴油机外部的油柜中，曲轴箱的油底壳只是用来收集各润滑部位流回的滑油，然后利用重力或滑油泵送回油柜，在借助滑油泵将滑油送入各摩擦部位。这种系统有以下优点：

   （1）可以避免柴油机工作中因油面的波动而导致润滑的失常。

   （2）减少曲轴箱内高温气体对滑油的影响，延长滑油使用的时间。

   （3）油底壳容积减小，使柴油机高度降低。

四、柴油发动机冷却系统

由于柴油机受热部件工作条件不同，所要求的冷却温度、压力和系统的基本组成也各不相同。因而各受热部件的冷却系统通常有几个单独的系统组成。一般分为缸套和气缸盖、活塞、喷油器三个冷却系统。缸套和气缸盖用淡水冷却，活塞和喷油器则有的用淡水冷却的，也有的用滑油冷却活塞，用柴油冷却喷油器的系统。

五、柴油发动机故障分析

润滑和冷却系统的故障往往是由于下列各方面的原因所导致的：

   （1）润滑油变质；

   （2）冷却水质量不符合要求；

   （3）系统的各种参数（如温度、压力、流量等）不正常；

   （4）系统中混入了空气或燃气，造成气塞。

 

Lubrication and cooling system for diesel engine
: Diesel engine lubricating oil and lubricating additive
Lubrication in diesel engines have the following roles:
(1) reduction mill
(2) cooling effect
(3) clean
(4) sealed
(5) the antiseptic effect
(6) to reduce noise
Second, the diesel engine cylinder lubrication
1, cylinder lubrication characteristics and modalities
Cylinder lubrication particularity lies first and foremost with high temperature, followed by the reciprocating motion of the piston speed in the vicinity of the Central maximum, zero at the top and bottom dead center, so only in the Middle piston stroke could achieve hydrodynamic lubrication. Again using poor quality fuel. For these reasons, especially its upper part of the cylinder liner, it is difficult to form a continuous integrity of oil-film, and therefore tend to be in the upper part of the cylinder liner wear the most serious.
Cylinder lubrication can generally be divided into oil-splash lubrication, and cylinder note in two ways.
(1) splash lubrication
Splash lubrication from the connecting rod big end and throw out and splash into the lubricating oil on the cylinder wall lubrication, typically does not require special lubrication device, the cylinder lubricating oil and crankcase oil is of the same oil and recycled, installing wiper at the piston skirt you want so that excess oil in the cylinder wall splash to scrape back into the crankcase.
(2) the cylinder oil lubricated
Cylinder oil lubricated using a dedicated lubrication system and equipment, cylinder oil by special oiling hole in the cylinder wall lubrication of injection into the cylinder wall surface. At present cross-head in diesel engines use this lubrication method.
Three, the diesel engine bearing lubrication
Place of bearings are lubricated by lubricating oil storage capacity are different, can be divided into wet-crankcase lubrication system (referred to as wet) and the dry-sump (referred to as dry) two broad categories.
Wet lubrication system is characterized by all of the oil is in the Save volume on crankcase oil pan, oil sump cycle oil tank role to play.
Dry lubrication system is characterized by lubricating oil in a separate oil tank outside the store in a diesel engine, the crank case oil pan just to collect the oil lubricated parts flow back, and then returned to the oil tank using gravity or sliding oil pump, through the sliding friction pump the oil into the site. This system has the following advantages:
(1) diesel engines can be avoided in the work of arrhythmia caused by fluctuations in oil lubrication of.
(2) reducing the impact of high temperature gas in the crankcase oil, extending the time lubricating oil.
(3) volume reduction of oil pan, engine height.
Four, diesel engine cooling system
Because the diesel engine heated parts working conditions are different, the required cooling temperatures, pressures, and consists of basic system differs. Thus heated parts of the cooling system typically consists of several separate systems. Is generally divided into the cylinder and the cylinder heads, Pistons, injectors three cooling systems. Cylinder and the cylinder head with fresh water cooling, piston and injector and some fresh water cooling, also use oil cooled Pistons, diesel injector cooling systems.
Failure analysis of five, diesel engine
Lubrication and cooling systems tend to be caused by the following reasons:
(1) modification of lubricating oil;
(2) cooling water quality does not meet the requirements;
(3) all kinds of system parameters (such as temperature, pressure, flow, and so on) is not normal;
(4) mixed with air or gas in the system, causing air lock.