Baldor BD Series User Manual page 12

BALDOR AIR COMPRESSOR
2、working principle
Working cycle can be divided into three processes: suction, compression and exhaust.
2.1 suction process
As shown in picture a (screw compressor suction process), the pair of gear is arrowed. Male rotor rotate
clockwise and female rotor anti-clockwise. As in the picture a, the rotor end is for exhaustion. When the
rotor rotates, the gear meshing with each other in the inlet end gradually disconnect, thus the composition
of the gear space volume increase gradually, and it connects with the air inlet, beginning to breathe in.
Rotor continues to rotate, and gear space volume increase. When gear space volume achieves the maximum,
that is, the gear with suction orifice is off, the suction process is over.
2.2 compression process
As shown in picture b, it is the compression process of screw compressor. Male and female rotor gear
mesh with each other to form a complete sealing connecting line and the air is surrounded in a closed
volume by rotor gear and casing. When the rotor rotates, the gear connecting line moves towards the
exhaustion end and the closed volume among tooth gradually decreases, and its air pressure increases.
When the gear space volume connects with
the exhaust orifice, air is compressed over.
2.3 exhaust process
As shown in picture c, gear space volume is divided by the rotor connecting line into low pressure side
and high side. When the volume of high pressure side connects with the exhaust orifice, which is the exhaust
process, the volume of low pressure side is in suction process. Along with the rotor rotating, the volume of
high pressure side reduces to zero, and the air is all discharged. At the same time, volume of the low
pressure side achieves maximum, completing the suction process. So that the suction, compression,
exhaustion processes go cycling.
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