ELECTRONIC ENGINE CONTROL
77. As stated in para. 8, some engines utilize a system of electronic control to monitor engine performance and make necessary control inputs to maintain certain engine parameters within predeter-mined limits. The main areas of control are engine shaft speeds and exhaust gas temperature (E.G.T.) which are continuously monitored during engine operation. Some types of electronic control function as a limiter only, that is, should engine shaft speed or
E.G.T.
approach the limits of safe operation, then an input is made to the fuel flow regulator (F.F.R.) to reduce the fuel flow thus maintaining shaft speed or
E.G.T.
at a safe level. Supervisory control systems may contain a limiter function but, basically, by using aircraft generated data, the system enables a more appropriate thrust setting to be selected quickly and
75.随着油门关闭，慢车状态由控制经慢车调节器和地面慢车电磁阀进行通风的空气量来确定。在工作中通过此二者同时放气，保证了在发动机有空气提取时仍有满意的空中慢车。通过关闭电磁阀可获得地面慢车时的低功率状态。
74．高压轴转速也由此辅助节流活门调节。万一其他控制装置失灵，而且油泵转速增加时，燃油压力将此节流活门关闭，并打开压力降溢流活门，从而减小燃油流量。
73．为了防止超过低压压气机的最大转速和发动机燃气温度。在燃油泵出口处装了一个活门，即辅助节流活门。在稳态运转状态下，该活门在弹簧力作用下保持打开。当到达极限状态时，燃油流量依据发动机的转速和温度信号而减少。信号被放大，并传至旋转作动筒，来减小可调限流器的面积。这个动作的效果是增大燃油压力，此压力又部分地关小节流活门。作用在压力降溢流活门表面上的高压燃油的压力增加，溢流活门打开，因而减步向喷嘴供应的燃油流量。
个输入量，使燃油流量减步，将轴转速或排气温度保持在安全水平上。监督控制系统可以具有限制器的功能，但是基本上它利用飞机提供的数据保证驾驶员能够快速而又精确地选择更为适当的推力位置。然后，控制系统进行微调，保持发动机的推力符合驾驶员预先设定的值，而不管大气条件如何变化。全权限数字式发动机控制器(F.A.D.E.C.)实际上接管了所有的稳态和瞬态的控制智能，并取代了燃油系统中绝大多数的液压机械和气动元件。因此，燃油系统简化到一个油泵、一个控制活门、一个单独的停车开关，以及在大量电子损坏的情况下必须要用来保证发动机安全的步量的附加装置。
78．全权限燃油控制器(F.A.F.C.)以与全权数字式发动机控制器相同的方式对发动机的燃油系统进行全电子式控制，但是它没有用来控制压气机空气流量系统的瞬态控制智能能力，而现在正用的发动机控制系统却具有这种能力。
76．与组合式加速和转速控制系统相似，这一燃油系统也没有采用增压活门来将燃油从油泵分配到主油路及初级油路。
发动机电子控制
77．如第8段所述，某些发动机采用电子控制系统来监视发动机的性能并提供必要的控制输入量，将一些发动机参数保持在预定的极限值之内。控制的主要领域是发动机轴转速及排气温度，这些都是在发动机工作中要连续监视的。有些类型的电子控制器仅仅起一个限制器功用。即一旦发动机轴转速或排气温度接近安全工作极限，那么就会向燃油流量调节器提供一
accurately by the pilot. The control system then makes small control adjustments to maintain engine thrust consistent with that pre-set by the pilot, regardless of changing atmospheric conditions. Full authority digital engine control (FAD.E.G.) takes over virtually all of the steady state and transient control intelligence and replaces most of the hydromechani-cal and pneumatic elements of the fuel system. The fuel system is thus reduced to a pump and control valve, an independent shut-off cock and a minimum of additional features necessary to keep the engine safe in the event of extensive electronic failure.
78. Full authority fuel control (F.A.F.C.) provides full electronic control of the engine fuel system in the same way as F.A.D.E.C., but has none of the transient control intelligence capability used to control the compressor airflow system as the existing engine control system is used for these.
Speed and temperature control amplifiers
79. The speed and temperature control amplifier receives signals from thermocouples measuring
E.G.T. and from speed probes sensing L.P. and in some cases, L.P. shaft speeds (N1 and N2). The amplifier basically comprises speed and temperature channels which monitor the signals sensed. If either N1, N2 or E.G.T. exceed pre-set datums, the amplifier output stage is triggered to connect an electrical supply to a solenoid valve (para. 47) or a variable restrictor (para. 73) which override the F.F.R. and cause a reduction in fuel flow. The limiter will only relinquish control back to the F.F.R. if the input conditions are altered (altitude, speed, ambient temperature or throttle lever position). The limiter system is designed to protect against parameters exceeding their design values under normal operation and basic fuel system failures.
Engine supervisory control
80. The engine supervisory control (E.S.C.) system performs a supervisory function by trimming the fuel flow scheduled by the fuel flow governor (F.F.G.) to match the actual engine power with a calculated engine power for a given throttle angle. The E.S.C. provides supervisory and limiting functions by means of a single control output signal to a torque motor in the F.F.G. In order to perform its supervisory function the E.S.C. monitors inputs of throttle angle, engine bleed state, engine pressure ratio (E.P.R.) and air data computer information (altitude, Mach number and temperatures). From this data the supervisory channel predicts the value of N1 required to achieve the command E.P.R. calculated for the throttle angle set by the pilot. Simultaneously a comparison is made between the command E.P.R. and the actual
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