油門出口壓力
調(diào)節(jié)器壓力
溫度微調(diào)信號
進(jìn)氣道空氣壓力
燃油控制裝置
高壓停車活門
低壓燃油
油泵供油(高壓燃油)
油門控制壓力
油門伺服壓力
伺服壓力
開
關(guān)
起動
阻尼油門
油門桿
控制活門
反壓活門
主燃油噴嘴
伺服濫流活門
流量控制
來自放大器
起動燃油噴嘴
帶孔套筒
伺服彈簧
油門開關(guān)
低壓轉(zhuǎn)速限制器和燃?xì)鉁囟瓤刂?br />
燃油泵
壓降控制膜片
旋轉(zhuǎn)式
溢流活門
電磁線圈
高壓軸調(diào)節(jié)器
(液壓機(jī)械式)
低壓
溢流活門
伺報(bào)控制膜片
真空膜盒
18．在穩(wěn)定狀態(tài)，阻尼油門活門保持平衡，因?yàn)橛烷T控制壓力加上彈簧力與油門伺服壓力互相抵消。壓力降掩制膜片前后的壓力處于平衡，油泵伺服壓力調(diào)節(jié)燃油泵，以供應(yīng)恒定的燃油流量。
圖10-5一種壓力控制系統(tǒng)(渦輪噴氣發(fā)動機(jī))
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19．當(dāng)油門打開，控制活門關(guān)閉套筒上的低壓燃油孔，油門伺服壓力增加。油門活門向選定的油門位置方向移動，直到低壓孔打開，油門活門前后的壓力恢復(fù)平衡為止。由壓力降控制膜片感測油門活門前后降低著的煉油壓差，關(guān)閉溢流活門，以增大油泵伺服壓力，進(jìn)而增加油泵輸出。溢流活門移到感測位置，控制油泵伺服機(jī)構(gòu)，使選定的油門位置下的正確的燃油流量得以保持。
Fuel system
20．在加速開始時(shí)，燃油控制如第l9段所述；但是，在預(yù)定的油門位置，發(fā)動機(jī)可得到更多的燃油，而且
在這一點(diǎn)，油門活門打開一個(gè)環(huán)形通道，引入額外的較高壓力的燃油(油泵通過一個(gè)限制器供油)。這部分額外的燃油進(jìn)一步增加了油門的伺服壓力，這壓力增加了油門活門的移動速度和向噴嘴的供油率。
21．在減速時(shí)，控制活門的移動通過伺服彈簧直接作用在油門活門上。控制活門的移動通過控制活門和油門活門，打開燃油的出口，通過低壓孔放出伺服燃油。因此，油門控制壓力使油門活門向關(guān)閉位置移動，因此，油門減少向噴嘴的供油量。
22．進(jìn)氣到空氣壓力由于飛機(jī)高度或飛行速度的變化而引起的變化，由燃油控制裝置中的膜片組件感測。隨著高度的增加，進(jìn)氣道空氣壓力相應(yīng)降低，真空膜片打開溢流活門，導(dǎo)致油泵行程減小，直到燃油流量與空氣流量匹配為止。反之，進(jìn)氣道空氣壓力增加，關(guān)閉溢流活門，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
圖10-6 由阻尼油門控制的加速性控制
throttle.
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油泵供油
油門出口
低壓
油門伺服
油門控制
燃油壓力
環(huán)腔
最終加速
開始加速
控制活門
油門桿
油門開關(guān)
關(guān)閉位置
23．高壓壓氣機(jī)軸的轉(zhuǎn)速用液壓機(jī)械調(diào)節(jié)器調(diào)節(jié)，它采用與發(fā)動機(jī)的轉(zhuǎn)速成正比的液壓油壓力作為其控制參數(shù)。旋轉(zhuǎn)式溢流活門感測發(fā)動機(jī)的轉(zhuǎn)速，然后用控制壓力來限制油泵的行程，借以防止高壓軸旋轉(zhuǎn)組件超轉(zhuǎn)。控制壓力不受燃油比重變化的影響。
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