油门出口压力
调节器压力
温度微调信号
进气道空气压力
燃油控制装置
高压停车活门
低压燃油
油泵供油(高压燃油)
油门控制压力
油门伺服压力
伺服压力
开
关
起动
阻尼油门
油门杆
控制活门
反压活门
主燃油喷嘴
伺服滥流活门
流量控制
来自放大器
起动燃油喷嘴
带孔套筒
伺服弹簧
油门开关
低压转速限制器和燃气温度控制
燃油泵
压降控制膜片
旋转式
溢流活门
电磁线圈
高压轴调节器
(液压机械式)
低压
溢流活门
伺报控制膜片
真空膜盒
18．在稳定状态，阻尼油门活门保持平衡，因为油门控制压力加上弹簧力与油门伺服压力互相抵消。压力降掩制膜片前后的压力处于平衡，油泵伺服压力调节燃油泵，以供应恒定的燃油流量。
图10-5一种压力控制系统(涡轮喷气发动机)
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19．当油门打开，控制活门关闭套筒上的低压燃油孔，油门伺服压力增加。油门活门向选定的油门位置方向移动，直到低压孔打开，油门活门前后的压力恢复平衡为止。由压力降控制膜片感测油门活门前后降低着的炼油压差，关闭溢流活门，以增大油泵伺服压力，进而增加油泵输出。溢流活门移到感测位置，控制油泵伺服机构，使选定的油门位置下的正确的燃油流量得以保持。
Fuel system
20．在加速开始时，燃油控制如第l9段所述；但是，在预定的油门位置，发动机可得到更多的燃油，而且
在这一点，油门活门打开一个环形通道，引入额外的较高压力的燃油(油泵通过一个限制器供油)。这部分额外的燃油进一步增加了油门的伺服压力，这压力增加了油门活门的移动速度和向喷嘴的供油率。
21．在减速时，控制活门的移动通过伺服弹簧直接作用在油门活门上。控制活门的移动通过控制活门和油门活门，打开燃油的出口，通过低压孔放出伺服燃油。因此，油门控制压力使油门活门向关闭位置移动，因此，油门减少向喷嘴的供油量。
22．进气到空气压力由于飞机高度或飞行速度的变化而引起的变化，由燃油控制装置中的膜片组件感测。随着高度的增加，进气道空气压力相应降低，真空膜片打开溢流活门，导致油泵行程减小，直到燃油流量与空气流量匹配为止。反之，进气道空气压力增加，关闭溢流活门，增加供油量。
The control valve slides freely within the bore of the throttle valve and is linked to the pilot's throttle by a rack and pinion mechanism. Movement of the throttle lever causes the throttle valve to progressively uncover ports in the sleeve and thus increase the fuel flow. Fig. 10-6 shows the throttle valve and control valve in their various controlling positions.
18.
At steady running conditions, the dashpot throttle valve is held in equilibrium by throttle servo pressure opposed by throttle control pressure plus spring force. The pressures across the pressure drop control diaphragm are in balance and the pump servo pressure adjusts the fuel pump to give a constant fuel flow.
19.
When the throttle is opened, the control valve closes the low pressure (L.P.) fuel port in the sleeve and the throttle servo pressure increases. The throttle valve moves towards the selected throttle position until the L.P. port opens and the pressure balance across the throttle valve is restored. The decreasing fuel pressure difference across the throttle valve is sensed by the pressure drop control diaphragm, which closes the spill valve to increase the pump servo pressure and therefore the pump output. The spill valve moves into the sensitive position, controlling the pump servo mechanism so that the correct fuel flow is maintained for the selected throttle position.
20.
During initial acceleration, fuel control is as described in para. 19; however, at a predetermined throttle position the engine can accept more fuel and at this point the throttle valve uncovers an annulus, so introducing extra fuel at a higher pressure (pump delivery through one restrictor). This extra fuel further increases the throttle servo pressure, which increases the speed of throttle valve travel and the rate of fuel supply to the spray nozzle.
21.
On deceleration, movement of the control valve acts directly on the throttle valve through the servo spring. Control valve movement opens the flow ports through the control valve and throttle valve, to bleed servo fuel through the L.P. port. Throttle control pressure then moves the throttle valve towards the closed position, thus reducing the fuel flow to the spray nozzles.
22.
Changes in air intake pressure, due to a change in aircraft altitude or forward speed, are sensed by the capsule assembly in the fuel control unit. With increased altitude and a corresponding decrease in air intake pressure, the evacuated capsule opens the spill valve, so causing a reduction in pump stroke
Fig. 10-6 Acceleration control by dashpot
图10-6 由阻尼油门控制的加速性控制
throttle.
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油泵供油
油门出口
低压
油门伺服
油门控制
燃油压力
环腔
最终加速
开始加速
控制活门
油门杆
油门开关
关闭位置
23．高压压气机轴的转速用液压机械调节器调节，它采用与发动机的转速成正比的液压油压力作为其控制参数。旋转式溢流活门感测发动机的转速，然后用控制压力来限制油泵的行程，借以防止高压轴旋转组件超转。控制压力不受燃油比重变化的影响。
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(48)
