R 1EFF : 001-003, 051-054, 1 21-51-00Page 38 1 1 Aug 01/05 1 1 1CES 1
R **ON A/C 004-049, 055-099, 101-149, 151-199, 201-299, 301-399,
The flow control valves 11HB (8HB) are installed upstream of the air conditioning packs 10HM (11HM). These valves are of the venturi type with a nominal 4 in. (101.5998 mm) diameter. Both have a built-in butterfly valve that controls the flow and can also perform a shut-off function. The flow control valve has three main assemblies:
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the valve body with its butterfly valve,
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the pneumatic actuator,
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the air pressure regulator.
A pneumatic actuator with a flexible diaphragm (1) controls the butterfly
valve. A return spring (2) closes the valve when there is no pressure
supply.
The air pressure regulator has:
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an air flow sensoring system,
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an electro-pneumatic adjustment system,
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an electrical venting system. The flow sensoring system has a pressure sensor which measures the differential pressure in the venturi-shaped valve body. The pressure sensor transfers the pressure into an electrical signal. It amplifies this signal and sends it to the pack controller 7HH (27HH) which calculates the actual air flow. The pack controller compares the air-flow with the pre-set value from the cockpit, and then calculates if the butterfly position must be changed.
One part of the electro-pneumatic regulator is a pressure reducer. If the pressure after the orifice G2 increases, the spring-loaded pressure reducer closes. This decreases the pressure in the pressure line and the reducer opens again. This protects the valve from damage caused by sudden pressure changes or too high an inlet pressure. Another part of the electro-pneumatic regulator is a torque motor which turns a quadrant. If the butterfly valve has to be opened, the torque motor turns the quadrant to a position closer to the opening of the pressure line. This increases the pressure after the orifice G1 and that pressurizes the pneumatic actuator of the valve and so the butterfly opens.
The electrical venting system includes an electromagnetic clapper. When the clapper is energized, solenoid S1 closes the valve by fully venting the pneumatic actuator chamber. When the solenoid is no longer energized, the pneumatic actuator chamber can be pressurized.
A pin situated on the butterfly axis actuates a microswitch, which supplies electrical power to indicate the fully-closed position of the valve.
R 1EFF : 004-049, 055-099, 101-149, 151-199, 1 21-51-00Page 39 1201-299, 301-399, 1Aug 01/05 1 1 1CES 1 The flow control valve has a safety feature which prevents a pack overheat: A pneumatic temperature sensor at the compressor outlet of the air cycle machine is connected to the pneumatic actuator. If the air temperature at the compressor outlet is too high, the pressure line in the temperature sensor opens and the pressurized air in the actuator vents through the now open temperature sensor. This reduces the pressure in the actuator and as an effect of this, the valve closes. The valve will open again if the compressor outlet temperature decreases. Another control feature is the downstream pressure regulator. If the pressure after the flow control valve is to high, a clapper opens and the pressure vents from the actuator. This closes the valve and the pressure after the valve decreases. The flow control valve can be closed manually with the use of a special vent screw. If you loosen the screw, the actuator looses pressure, the valve closes and then you use the same screw to fix the valve in the closed position.
R **ON A/C 401-499,
The flow control units 23HB (24HB) are installed upstream of the air conditioning packs 10HM (11HM). The flow control valves of the flow control units are electrically commanded, pneumatically actuated and have a nominal diameter of 4 in. (101.5998 mm). Both have a built-in butterfly valve that controls the flow and can also perform a shut-off function. The flow control valve has the following main components:
-the valve body with venturi,
-3 chamber pneumatic actuator,
-torque-motor electrical regulation,
-contactless duplex position sensor (Hall-sensor)
-integral DPS and PIP sensors,
-downstream pressure limiter,
- on/off solenoid
-mode selection selenoid. Actuator The actuator has 3 pneumatic chambers, eliminating the need for a constant pressure regulator, increasing reliability and resistance to pollution. The actuator opens or closes the FCV butterfly valve using the air pressure available in the main actuator chamber. 中國航空網 www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：A320飛機維護手冊 AMM AIR CONDITIONING 空調 3(91)
