P.C.U. lever is operated to reverse the pitch of the propeller.
INSTRUMENTATION
9. The performance of the engine and the operation of the engine systems are shown on gauges or by the operation of flag or dolls-eye type indicators. A diagrammatic arrangement of the control and instru-mentation for a turbo-jet engine is shown in fig. 12-2.

圖12-2 發(fā)動(dòng)機(jī)控制和儀表的布置圖
Fig. 12-2 Diagrammatic arrangement of engine control and instrumentation.

Controls and instrumentation

發(fā)動(dòng)機(jī)推力
 
10．發(fā)動(dòng)機(jī)的推力用推力計(jì)來(lái)指示。推力計(jì)有兩種基本類型，第一種測(cè)量渦輪出口或噴管壓力，第二種稱為發(fā)動(dòng)機(jī)壓比(E.P.R.)表，測(cè)量?jī)煞N或三種參數(shù)之比。當(dāng)測(cè)量發(fā)動(dòng)機(jī)壓比時(shí),該壓比通常是噴管的壓力與壓氣機(jī)進(jìn)口壓力之比。但是，對(duì)于風(fēng)扇發(fā)動(dòng)機(jī)來(lái)說(shuō),該壓比可以是渦輪出口和風(fēng)扇出口的綜合壓力與壓氣機(jī)進(jìn)口壓力之比。

14.發(fā)動(dòng)機(jī)壓比既可以由電機(jī)械式，也可以由電子式傳感器來(lái)指示。對(duì)于這兩種情況，傳感器的輸入是發(fā)動(dòng)機(jī)的進(jìn)口壓力(P1)及由風(fēng)扇出口壓力和渦輪排氣壓力構(gòu)成的綜臺(tái)壓力(PINT)。有些情況下單獨(dú)使用風(fēng)扇出口壓力或者渦輪排氣壓力取代PINT。
圖12-3 電機(jī)械式發(fā)動(dòng)機(jī)壓比(E.P.R.)傳感器
15.電機(jī)械式系統(tǒng)對(duì)壓力改變的指示方式是采用傳感器膜盒（圖12-3）使壓力傳感器的中心軸偏移，導(dǎo)致軛架相當(dāng)于A.A軸旋轉(zhuǎn)。這一運(yùn)動(dòng)由線性可調(diào)電壓差變壓器感測(cè)，并轉(zhuǎn)換成為交流電信號(hào)，經(jīng)過(guò)放大后作用在伺服馬達(dá)的控制繞組上。
Controls and instrumentation

16.伺服馬達(dá)通過(guò)齒輪改變通向發(fā)動(dòng)機(jī)壓力比指示器的電位計(jì)輸出低壓信號(hào)，同時(shí)驅(qū)動(dòng)平衡架沿著與軛架的原始運(yùn)動(dòng)相同的方向運(yùn)動(dòng)，直到通向馬達(dá)的線性可調(diào)電壓差變壓器信號(hào)消失和系統(tǒng)穩(wěn)定在新的位置為止。
 
17.電子式發(fā)動(dòng)機(jī)壓比系統(tǒng)采用兩個(gè)震動(dòng)筒式壓力傳感器，它們感測(cè)發(fā)動(dòng)機(jī)空氣壓力，并在與這些壓力相關(guān)的頻率下振動(dòng)。依據(jù)這些振動(dòng)頻率，計(jì)算出發(fā)動(dòng)機(jī)壓比的電信號(hào)，然后將信號(hào)輸入發(fā)動(dòng)機(jī)壓比表和電子式發(fā)動(dòng)機(jī)控制系統(tǒng)（第10章）。
Engine thrust the minimum thrust output can be checked under all
10.
The thrust of an engine is shown on a thrust-meter, which will be one of two basic types; the first measures turbine discharge or jet pipe pressure, and the second, known as an engine pressure ratio (E.P.R.) gauge, measures the ratio of two or three parameters. When E.P.R. is measured, the ratio is usually that of jet pipe pressure to compressor inlet pressure. However, on a fan engine the ratio may be that of integrated turbine discharge and fan outlet pressures to compressor inlet pressure.

11.
In each instance, an indication of thrust output is given, although when only the turbine discharge pressure is measured, correction is necessary for variation of inlet pressure; however, both types may require correction for variation of ambient air temperature. To compensate for ambient atmospheric conditions, it is possible to set a correction figure to a sub-scale on the gauge; thus,

operating conditions.
12.
Suitably positioned pilot tubes sense the pressure or pressures appropriate to the type of indication being taken from the engine. The pilot tubes are either directly connected to the indicator or to a pressure transmitter that is electrically connected to the indicator.

13.
An indicator that shows only the turbine discharge pressure is basically a gauge, the dial of which may be marked in pounds per square inch (p.s.i.), inches of mercury (in. Hg.), or a percentage of the maximum thrust.

14.
E.P.R. can be indicated by either electro-mechanical or electronic transmitters. In both cases the inputs to the transmitter are engine inlet pressure (P1) and an integrated pressure (PINT) comprised of

20.除了提供發(fā)動(dòng)機(jī)的功率指示之外，扭矩計(jì)系統(tǒng)還在由于功率故障造成扭矩計(jì)滑油壓力降低時(shí)，用于自動(dòng)控制螺旋槳順槳系統(tǒng)。對(duì)于某些安裝條件下，它還用于協(xié)助噴水系統(tǒng)的自動(dòng)操作，以便在外界溫度較高或在高海拔飛機(jī)場(chǎng)恢復(fù)或增大起飛功率（第17章）。
圖12-4 簡(jiǎn)單的扭矩系統(tǒng)
Fig. 12-4 A simple torquemeter system.

22.發(fā)動(dòng)機(jī)轉(zhuǎn)速指示由發(fā)動(dòng)機(jī)驅(qū)動(dòng)的一個(gè)小型發(fā)電機(jī)經(jīng)電路傳給指示器，它顯示出實(shí)際的每分鐘轉(zhuǎn)速（r.p.m.)，或者顯示出發(fā)動(dòng)機(jī)最大轉(zhuǎn)速的百分比（圖12-5）。發(fā)動(dòng)機(jī)轉(zhuǎn)速常常用于估算發(fā)動(dòng)機(jī)扭力。但是，由于進(jìn)口溫度和壓力狀態(tài)會(huì)影響給定的發(fā)動(dòng)機(jī)轉(zhuǎn)速下的推力，所以它給出的不是推力的 指示值。
發(fā)動(dòng)機(jī)轉(zhuǎn)速

21.所有的發(fā)動(dòng)機(jī)都有它們的轉(zhuǎn)速指示。對(duì)于雙轉(zhuǎn)子或三轉(zhuǎn)子發(fā)動(dòng)機(jī)，總是要指示高壓轉(zhuǎn)子的轉(zhuǎn)速。在多數(shù)情況下，還有另外的指示器顯示低壓和中壓轉(zhuǎn)子的轉(zhuǎn)速。
Controls and instrumentation

fan outlet and turbine exhaust pressures. In some cases either fan outlet pressure or turbine exhaust pressure are used alone in place of PINT.
15. The electro-mechanical system indicates a change in pressure by using transducer capsules (fig. 12-3) to deflect the centre shaft of the pressure transducer causing the yoke to pivot about the axis
A.A. This movement is sensed by the linear variable differential transformer (L.V.D.T.) and converted to an
a.c. electrical signal which is amplified and applied to the control winding of the servo motor.
16. The servo motor, through the gears, alters the potentiometer output voltage signal to the E.P.R. indicator and simultaneously drives the gimbal in the same direction as the initial yoke movement until the
　
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