齒間集油容量
(在供油泵中的滑油或在回油泵中的空氣／滑油)

圖8-5 一種齒輪泵的工作原理
Fig. 8-5 Principle of a gear pump.
cylinder is achieved by a spring forcing the piston to its original position. This reduces the pressure between the cylinder and the oil tank which allows the oil replenshing valves to open until the cylinder is recharged.
20.
The most common type of oil distribution device is a simple orifice which directs a metered amount of oil onto its target. These jet orifices are positioned as close to the target area as possible to overcome the possibility of the local turbulent environment deflecting the jet of oil. The smallest diameter of a jet orifice is 0.04 inch which allows a flow of 12 gallons per hour when operating at a pressure of 40 lb. per sq. in. The use of restrictors upstream can reduce the flow rate if required.

21.
All engines transfer heat to the oil by friction, churning and windage within a bearing chamber or gearbox. It is therefore common practice to fit an oil cooler in recirculatory oil systems. The cooling medium may be fuel or air and, in some instances, both fuel-cooled and air-cooled coolers are used.

低壓進口
低壓滑油
高壓滑油
機匣
高壓出口
21.所有的發動機都會因軸承腔或齒輪箱內的摩擦、攪動和風阻向滑油傳熱。因此，一般的做法是在循環滑油系統中裝一個滑油散熱器。冷卻介質可以是燃油或空氣，在某些情況下同時使用燃油冷卻的和空氣冷卻的散熱器。
23．燃油冷卻滑油散熱器(圖8-7)有一個蜂窩散熱組件，由折流板分隔成段。大量的導管穿過蜂窩散熱器輸送燃油，滑油在折流板的引導下經一系列通道流過這些管子外面。熱量由滑油傳給燃油，因此降低了滑油溫度。
22．某些同時使用兩種散熱器的發動機，可以設一套電子監控系統，只在需要的時候才將空氣冷卻的散熱器打開。這樣可保持理想的滑油溫度和提高總的熱效率。
24．燃油冷卻滑油散熱器在滑油的進口和出口之間裝有一個旁通活門。該活門在預先設定的散熱器前后壓差下工作，從而防止在堵塞的情況下發動機缺滑油。通常在散熱器的輸油路上還安裝一個壓力保持活門，它保證滑油壓力總是高于燃油壓力。在散熱器發生內部故障的情況下，滑油會漏入燃油系統，而不是燃油漏入滑油系統發生潛在的危險。

25.空氣冷卻滑油散熱器與燃油冷卻式相比，兩者在結構和工作上都相似。主要差別是利用空氣作為冷卻介質。
Lubrication

圖8-6 一次壓射式滑油泵
Fig. 8-6 A single-shot oil pump.
22.
Some engines which utilize both types of cooler may incorporate an electronic monitoring system which switches in the air-cooled cooler only when it is necessary. This maintains the ideal oil temperature and improves the overall thermal efficiency.

23.
The fuel-cooled oil cooler (fig. 8-7) has a matrix which is divided into sections by baffle plates. A large number of tubes convey the fuel through the matrix, the oil being directed by the baffle plates in a series of passes across the tubes. Heat is transferred from the oil to the fuel, thus lowering the oil temperature.

24.
The fuel-cooled oil cooler incorporates a bypass valve fitted across the oil inlet and outlet. The valve operates at a pre-set pressure difference across the

高壓燃油
低壓燃油
cooler and thus prevents engine oil starvation in the event of a blockage. A pressure maintaining valve is usually located in the feed line of the cooler which ensures that the oil pressure is always higher than the fuel pressure. In the event of a cooler internal fault developing, the oil will leak into the fuel system rather than the potentially dangerous leakage of fuel into the oil system.
25.
The air-cooled oil cooler is similar to the fuel-cooled type in both construction and operation; the main difference is that air is used as the cooling medium.

26.
Magnetic plugs, or chip detectors (fig. 8-8), are fitted on the scavenge (return) side to collect ferritic

油泵再次充油

滑油出口
滑油溫度傳感囂
滑油旁路活門
滑油進口
燃油進口
蜂窩結構
散熱組件
低壓燃油
供滑油
折流板
燃油出口
Lubrication
26．磁性堵頭，即磁性探屑器(圖8-8)裝在回油路上，用來收集來自各個軸承腔的鐵屑。它們基本上是插在滑油流道中的永久磁鐵，固定在甘行封嚴的活門座上。設計中采用了一些特有的保險辦法，以保證探屑器能正確地安置在活門座上。根據檢查，它們可以提供故障臨近的警告，而無需拆卸和檢查油濾。它們設計成在維護檢查時拆卸，用于狀態監視的目的(第24章)，而不發生滑油損失。另外，它們還可能接通駕駛艙的警告系統，提供飛行中的指示。
圖8-7 一種低壓燃油冷卻滑油散熱器
Fig. 8-7 A low pressure fuel-cooled oil cooler.

圖8-8 一種磁性探屑器
28．為防止滑油箱、齒輪箱和軸承腔中的空氣壓力過高，在潤滑系統中有通大氣的通風口。在空氣通往機外之前，空氣中的任何油滴將被離心通風機分離出來。有些通風機中有多孔中間體，構成空氣分離段，提高了油氣分離的效率(圖8-10)。
27.在某些發動機上，為了盡量減小從旋轉組件傳向軸承座的動力載荷的影響，采用了“擠壓油膜”式軸承(圖8-9)。它們在軸承外圈和軸承座之間留有很小的間隙，該間隙中充滿了滑油。該油膜阻尼了旋轉組件的徑向運動及傳向軸承座的動力載荷，因此減低了發動機的振動水平及疲勞損壞的可能性。
　
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