52.燃油流量調節器由發動機通過齒輪系驅動。它有2個離心調節器，即轉速控制調節器和壓力降控制調節器。齒輪系還帶動2個滑閥旋轉。一個閥是可調節流套筒，帶有三角形孔，即可調節流孔，該套筒在膜盒組件作用下產生軸向移動。可調節流孔套筒在一個不旋轉的調節器套筒中移動，后者靠轉速控制調節器作軸向運動。另一個閥，即壓力降控制閥，由壓力降控制調節器軸向驅動。它也有一十三角形小孔，即壓力降控制孔和一個固定面積的長方孔。轉速控制調節器的位置南油門桿通過調節器內的一個凸輪、一根彈簧和一個托架臂設定。
54.當進氣道空氣壓力為一恒定值時，膜盒載荷使旋轉的可調節流孔套筒保持在一個固定的軸向位置。由于油門位置是固定的，它在轉速控制調節器上保持一個固定的載荷，因而只要轉速恒定，調節器套簡便處于一個固定的位置。
53．在任何穩定運轉狀態，發動機轉速由控制燃油流量的調節器控制。靠油泵伺服活塞上施加的系統壓力差，使燃油泵的供油被固定在一個恒定值。該壓力差用于平衡伺服活塞的彈簧力。
Fuel system

53.
At any steady running condition, the engine speed is governed by the regulator controlling the fuel flow. The fuel pump delivery is fixed at a constant value by applying the system pressure difference to the fuel pump servo piston. This is arranged to balance the servo piston spring forces.

54.
When the air intake pressure is at a constant value, the rotating V.M.O. sleeve is held in a fixed axial position by the capsule loading. The fixed throttle setting maintains a set load on the speed control governor and, as the r.p.m. is constant, the governor sleeve is held in a fixed position.

55.
The fuel pump delivery is passed to the annulus surrounding the V.M.O.; the annulus area is controlled by the governor sleeve, and the exposed area of the orifice is set by the axial position of the

V.M.O. sleeve. Consequently, fuel passes to the inside of the sleeve at a constant flow and therefore at a constant pressure difference.
56.
The pressure drop control valve, which also forms a piston, senses the pressure difference across the V.M.O. and maintains the fuel flow at a fixed value in relation to a function of engine speed, by controlling the exposed area of the pressure drop control orifice.

57.
When the throttle is slowly opened, the load on the speed control governor is increased, so moving the governor sleeve to increase the V.M.O. annulus area. The effect of opening the V.M.O. is to reduce the pressure difference and this is sensed by the pressure drop control governor, which opens the pressure drop valve. The reduced system pressure difference is immediately sensed by the fuel pump servo piston, which increases the pump stroke and consequently the fuel output. The increased compressor delivery pressure acts on the capsule assembly, which gradually opens the V.M.O. so that the fuel flow and engine speed continue to increase. At the speed selected, centrifugal forces acting on the speed control governor move the governor sleeve to reduce the V.M.O. annulus area. The resultant increased pressure difference is sensed by the pressure drop control governor, which adjusts the pressure drop valve to a point at which the pump servo system gives an output to match the engine requirements. The function of the governors and the control of the fuel flow is shown diagrammatically in fig. 10-10.

58.
During a rapid acceleration, the initial degree of overselling is mechanically controlled by a stop that limits the opening movement of the speed control

governor sleeve. A similar stop also prevents the fuel supply from being completely cut off by the governor sleeve during a rapid deceleration.
59.
Changes in altitude or forward speed of the aircraft vary the fuel flow required to maintain a constant engine speed. To provide this control, the capsule assembly senses changes in H.P. compressor inlet and delivery pressures and adjusts the V.M.O. accordingly. For instance, as the aircraft altitude increases, the compressor delivery pressure falls and the capsule assembly expands to reduce the V.M.O. The increased system pressure drop is sensed by the fuel pump servo piston, which adjusts the pump output to match the reduced airflow and so maintain a constant engine speed. Conversely, an increase in aircraft forward speed causes the capsule assembly to be compressed and increase the V.M.O. The reduced system pressure drop causes the fuel pump to increase its output to match the increased airflow.

60.
To prevent the maximum gas temperature from being exceeded, fuel flow is reduced in response to signals from thermocouples sensing the temperature (Part 12). When the maximum temperature is reached, the signals are amplified and passed to a rotary actuator which adjusts the throttle mechanism. This movement has the same effect on fuel flow as manual operation of the throttle.

61.
To ensure that the engine is not overstressed, the H.P. compressor delivery pressure is controlled to a predetermined value. At this value, a pressure limiting device, known as a power limiter, reduces the pressure in the capsule chamber, thus allowing the capsule assembly to expand and reduce the V.M.O. so preventing any further increase in fuel flow.
　
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