Hanbell RC2-D, Техническое руководство

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RC2-D Technical Manual
3. Capacity control system
3.1 Compression process
At the beginning of the compression cycle, as the male rotor and female rotor unmesh, gas from suction
port fills the interlobe space (refer to the dark area in Figure 3-1). Refrigerant at suction pressure
continues to fill it, until the trailing lobe crosses the suction area and the gas is trapped inside the
interlobe space. As the male rotor and female rotor meshes, the interlobe space moves towards to
discharge end and its volume decreases so that gas pressure increases consequently. Gas is discharged
from the interlobe space when the leading lobe crosses the discharge port whose volume ratio is
designed differently for various applications.
（
A
）
Suction and sealing
（
B
）
Compression
（
C
）
Discharge
Figure 3-1 Compression process
3.2 Step capacity control system
RC2-D series screw compressors are equipped with either 3&4-step capacity control system .
This capacity control systems consist of slide valve, piston rod, piston cylinde and piston ring.
The slide valve and the piston are connected by a piston rod; the oil pressure in the system
pushes the piston in the cylinder to move, thus the slide valve moves .
Step capacity control, as shown in Figure 3-2.
The lubricating oil flows out of the oil tank and
passes through the oil filter and capillary tube.
As the oil pressure is higher than the sum of
the right end spring force and the refrigerant
pressure, the lubricating oil enters the piston
cylinder. Under the action of pressure
difference, the piston moves to the right, the
effective compression volume in the
compression chamber increase. At this time, the discharge volume of refrigerant gas increases,
resulting in the increase of refrigeration capacity. However, when any one of the step (3-stage
/ 4-stage) capacity control solenoid valves is energized, the high-pressure oil in the piston
Figure 3-2 (3&4 step) Capacity control