37.
During a rapid acceleration, the sudden decrease in throttle pressure difference is sensed by the A.S.U., causing the spill valve to close, Such a rapid increase in fuel supply would, however, create an excessive gas temperature and also cause the compressor to surge (Part 3). This occurs because the inertia of the rotating assembly results in an appreciable time lag in the rate of airflow increase. It is essential therefore, to have an acceleration control to override the A.S.U. to give a corresponding lag in the rate of fuel flow increase.
38.
The rapid initial increase of fuel flow causes a rise in the pressure difference across the fuel metering plunger and this is sensed by a diaphragm in the pressure drop control section. At a fixed value of over fuelling, the pressure drop control diaphragm opens its servo spill valve to override the A.S.U, and maintains a constant pressure difference across the metering plunger.
39.
The increased fuel supply causes the engine to accelerate and the fuel metering plunger gives the maximum permissible fuel flow to match the increasing compressor delivery pressure. This it achieves through the A.C.U. servo system, which is under the control of a spill valve operated by compressor delivery air pressure acting on a capsule.
40.
As the compressor delivery pressure continues to rise, the capsule is compressed to open the spill valve and to bleed pressure from above the metering plunger. Pump delivery pressure acting underneath the plunger causes it to lift, this increases the area of the main fuel flow passage.
37.当快速加速时，高度传感装置感测到油门压差突然降低，导致溢流活门关闭。然而，燃油供应如此急速的增加会产生过高的燃气温度，并导致压气机喘振(第3章)。这种情况发生的原因是，旋转组件的惯性使得空气流量增加的速率有相当大的时间滞后。因而必须有一套加速控制器来超控高度传感装置，使燃油流量增加的速率也有相应的滞后。
104
气机出口压力相匹配。这一功能是通过加速控制装置的伺服系统而实现的。该伺服系统由溢流活门控制，而该活门由作用在膜片上的压气机出口空气压力来操作。
40．当压气机供气压力继续提高时，膜片受压缩，将溢流活门打开，从节流柱塞上方释放压力。作用在柱塞下方的油泵的供油压力将其升起，这样便增大了主燃油流动通道的面积。
38．燃油流量快速地开始增加导致燃油节流柱塞前后的压差增加，这由压降控制部分的膜片感测。在过量供油的某个定值下，压降控制膜片打开它的伺服溢流活门，超控高度传感装置的控制，并使节流柱塞前后的压差保持恒定。
39．增大了的燃油供应量导致发动机加速，同时，燃油节流柱塞供应允许的最大燃油流量，使之与增加着的压
Fuel system
41. The pressure drop control spill valve closes to the fuel output in the same way as the gas increase the fuel pump delivery and maintains the temperature control. 41．压降控制溢流活门关闭，使燃油泵供油增加，并保持柱塞前后的控制压差。因此，燃油流量随着压气机空气流量的增加逐渐增加。通过负责增大膜片上压力信号的空气开关能自动改变过量供油的程
度。现在，压气机供气压力的全部数值已传递给加速控制装置的膜片组件，从而增加了节流柱塞的开启率。
42．当受控的过量供油继续进行时，油门活门前后的压差增大。当其到达控制值时，高度传感装置由于增加了比例流量而起作用，重新为喷嘴提供稳定的燃油流量。
43．发动机转速调节器可以是第15段所述的压力控制式，也可以是第23段所述的液压机械式的。
44．液压机械调节器的伺服压力控制，与压力控制调节器非常相似，但调节器压力由油泵供油流过一个限制器之后取得，限制压力受旋转式溢流活门的控制；这种调节器不受燃油比重改变的影响。
controlling pressure difference across the plunger. The fuel flow, therefore, progressively rises as airflow through the compressor increases. The degree of overfuelling can be automatically changed by the air switch, which increases the pressure signal on to the capsule. The full value of compressor delivery pressure is now passed on to the A.C.U. capsule assembly, thus increasing the opening rate of the metering plunger.
42. As the controlled overfuelling continues, the pressure difference across the throttle valve increases. When it reaches the controlling value, the
A.S.U. takes over due to the increasing proportional flow and again gives a steady fuel flow to the spray nozzles.
43.
The engine speed governor can be of the pressure control type described in para. 15, or a hydro-mechanical governor as described in para. 23.
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