图8-1 一种减压活门式滑油系统
Fig. 8-1 A pressure relief valve type oil system.
全流量系统
7．虽然对于具有低轴承腔压力的发动机来说，轴承腔压力不会随发动机转速的增加而过量增加，减压活门系统可以满意地工作。但是，对于具有高轴承腔压力的发动机来说，它就成了不符合要求的系统。例如，假如轴承腔的最大压力为90磅／平方英寸，为了在滑油供油喷嘴处产生40磅／平方英寸的压力降，就要求减压活门设定压力为l30磅／平方英寸。这时就要使油泵很大，并且在较低的转速下难以与要求的滑油流量相匹配。
system. Scavenge pumps return the oil to the tank via the oil cooler. On entering the tank, the oil is de-aerated ready for recirculation.
Full flow system
7. Although the pressure relief valve system operates satisfactorily for engines which have a low bearing chamber pressure, which does not unduly increase with engine speed, it becomes an undesirable system for engines which have high chamber pressures. For example, if a bearing chamber has a maximum pressure of 90 lb. per sq. in. It would require a pressure relief valve setting of 130 lb. per sq. in. to produce a pressure drop of 40 lb. per sq. in. at the oil feed jet. This results in the
Lubrication
need for large pumps and difficulty in matching the required oil flow at slower speeds.
8. The full flow system achieves the desired oil flow rates throughout the complete engine speed range by dispensing with the pressure relief valve and allowing the pressure pump delivery pressure to supply directly the oil feed jets. Fig. 8-2 shows an example of this system which may be found on a turbo-fan engine. The pressure pump size is determined by the flow required at maximum engine speed. The use of this system allows smaller pressure and scavenge pumps to be used since the large volume of oil which is spilled by the pressure relief valve system at maximum engine speed is obviated.
图8-2 一种全流量式滑油系统
8.全流量系统可以在整个发动机转速范围内达到要求的滑油流量，它不用减压活门，而允许增压泵直接向滑油供油喷嘴供压。图8-2示出了这种系统的一个例子，它可以在涡轮风扇发动机上找到。增压油泵的尺寸由发动机最大转速下要求的滑油流量决定。由于不像减压活门系统那样在最大发动机转速下溢出大量的滑油，所以使用本系统允许使用较小的压力和较小的回油泵。
Fig. 8-2 A full flow type oil system.
来自滑油箱
滑油压差开关
减压活门
高压油滤
滑油泵组件
供油
回油
通风空气
离心式通风机
节流后溢油
流回滑油箱
油气分离器盘
滑油压力传感器和低压警告开关
燃油冷却滑油散热器 空气冷却滑油散热器
9．为了防止高的滑油压力损坏油滤或滑油散热器，安装了限压活门，使滑油绕过这些装置而经旁路回油。一般情况下，这些活门只有在冷起动条件下或当发生堵塞时才工作。通过压差开关可以在驾驶舱中提前给出油滤堵塞的警告指示，该开关感受油滤进口和出口的压力差。
9. To prevent high oil pressures from damaging filters or coolers, pressure limiting valves are fitted to by-pass these units. These valves normally only operate under cold starting conditions or in the event of a blockage. Advance warning of a blocked filter may be indicated in the cockpit by a differential pressure switch which senses an increase in the pressure difference between the inlet and outlet of the filter.
Total loss (expendable) system
10. For engines which run for periods of short duration, such as booster and vertical lift engines,
Lubrication
the total loss oil system is generally used. The system is simple and incurs low weight penalties because it requires no oil cooler, scavenge pump or filters. On some engines oil is delivered in a continuous flow to the bearings by a plunger-type pump, indirectly driven from the compressor shaft; on others it is delivered by a piston-type pump operated by fuel pressure (fig. 8-3). In the latter, the oil supply is automatically selected by the high pressure fuel shut-off valve (cock) during engine starting and is delivered as a single shot to the front and rear bearings. On some engines provision is made for a
滑油／空气雾引射喷口
油箱压力
供滑油
滑油／空气雾
高压燃油
低压燃油
总损耗（可消耗的）系统
10．对于短时间运转的发动机，如助推发动机和垂直升力发动机，通常使用总损耗滑油系统。这种系统简单而且重量方而的负担较小，因为它不需要滑油散热器，回油泵或油滤。在某些发动机上，滑油由一个柱塞式泵连续地向轴承供油。该泵由上压气机轴间接驱动。在其它发动机上，滑油由燃油压力(图8-3)驱动的活塞式泵供应。对于后者，供油是由高
压燃油停车开关在发动机起动时自动选择的，向？后轴承只射油一次。在某些发动机上，还备有某种措施按预定的时间间隔第二次射油，但是只向后轴承射油。
后轴承
空心出口导向叶片
压气机空气
一次注油滑油泵
油门装置
燃油槽
图8-3 一种总损耗(消耗性)滑油系统
Fig. 8-3 A total loss (expendable) oil system.
11．滑油在润滑了燃油装置和前轴承之后，由前轴承排入集油槽，然后通过一个引射喷口喷入主燃气流。流过后轴承的滑油排入轴承后面的收油池，滑油在离心力作用下留在那里直至发动机停车。然后该滑油由位于排气装置内锥中的中心管排出机外。 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：劳斯莱斯喷气引擎－中英(37)
