二、柴油發動機汽缸潤滑

1、氣缸潤滑的特點和方式

氣缸潤滑的特殊性首先在于高的工作溫度，其次是活塞在往復運動時的速度在中部附近最大，在上、下止點處為零，因此只有在活塞行程中部才有可能實現液體動壓潤滑。再次是使用劣質的燃油。由于這些原因，氣缸套特別是它的上部，很難形成連續完整的油膜，因此一般在氣缸套的上部磨損嚴重。

氣缸潤滑一般可分為飛濺潤滑和氣缸注油潤滑兩種方式。

   （1）飛濺潤滑

飛濺潤滑靠從連桿大端甩出并飛濺到氣缸壁上的滑油來潤滑，一般不需要專門的潤滑裝置，氣缸滑油與曲軸箱滑油屬同一油品且循環使用，在活塞裙部需裝設刮油環以便把飛濺到缸壁的多余滑油刮回曲軸箱。

   （2）氣缸注油潤滑

氣缸注油潤滑使用專用的潤滑系統及設備，把專用氣缸油經缸壁上的注油孔噴注到氣缸壁表面進行潤滑。目前在十字頭式柴油機中均使用此種潤滑方式。

三、柴油發動機軸承潤滑

軸承潤滑按滑油存容場所的不同，潤滑系統可分為濕曲軸箱式（簡稱濕式）和干曲軸箱式（簡稱干式）兩大類。

濕式潤滑系統的特點是全部滑油都存容于曲軸箱的油底殼中，油底殼起循環油柜的作用。

干式潤滑系統的特點是滑油單獨存放在柴油機外部的油柜中，曲軸箱的油底殼只是用來收集各潤滑部位流回的滑油，然后利用重力或滑油泵送回油柜，在借助滑油泵將滑油送入各摩擦部位。這種系統有以下優點：

   （1）可以避免柴油機工作中因油面的波動而導致潤滑的失常。

   （2）減少曲軸箱內高溫氣體對滑油的影響，延長滑油使用的時間。

   （3）油底殼容積減小，使柴油機高度降低。

四、柴油發動機冷卻系統

由于柴油機受熱部件工作條件不同，所要求的冷卻溫度、壓力和系統的基本組成也各不相同。因而各受熱部件的冷卻系統通常有幾個單獨的系統組成。一般分為缸套和氣缸蓋、活塞、噴油器三個冷卻系統。缸套和氣缸蓋用淡水冷卻，活塞和噴油器則有的用淡水冷卻的，也有的用滑油冷卻活塞，用柴油冷卻噴油器的系統。

五、柴油發動機故障分析

潤滑和冷卻系統的故障往往是由于下列各方面的原因所導致的：

   （1）潤滑油變質；

   （2）冷卻水質量不符合要求；

   （3）系統的各種參數（如溫度、壓力、流量等）不正常；

   （4）系統中混入了空氣或燃氣，造成氣塞。

 

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.