Gardner Denver ELECTRA-SAVER ETY99A, Руководство пользователя

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13–13–600 Page 1
SECTION 1
GENERAL INFORMATION
FIGURE 1–1 – COMPRESSION CYCLE
COMPRESSOR – The Gardner Denver Electra–Sav-
er
R
compressor is a single stage, positive displace-
ment rotary machine using meshing helical rotors to ef-
fect compression. The input drive shaft and helical
drive gear are supported in the gear case by high ca-
pacity tapered roller bearings. The drive gear meshes
with a driven gear mounted on the main rotor shaft to
drive the rotors. Both rotors are supported between
large capacity anti–friction bearings located outside the
compression chamber. Single width cylindrical roller
bearings are used at the inlet end of the rotors. Early
models used two (2) heavy–duty, single–row, angular
contact ball bearings at the discharge end to locate
each rotor axially and carry all thrust loads; later mod-
els use tapered roller bearings in this location.
COMPRESSION PRINCIPLE (FIGURE 1–1) – Com-
pression is accomplished by the main and secondary
rotors synchronously meshing in a one–piece cylinder.
The main rotor has four (4) helical lobes 90
_
apart. The
secondary rotor has five (5) matching helical grooves
72
_
apart to allow meshing with main rotor lobes.
The air inlet port is located on top of the compressor
near the center. The discharge port is near the bottom
at the opposite end of the compressor cylinder. Figure
1–1 is an inverted view to show inlet and discharge
ports. The compression cycle begins as rotors unmesh
at the inlet port and air is drawn into the cavity between
the main rotor lobes and secondary rotor grooves (A).
When the rotors pass the inlet port cutoff, air is trapped
in the interlobe cavity and flows axially with the meshing
rotors (B). As meshing continues, more of the main ro-
tor lobe enters the secondary rotor groove, normal vol-
ume is reduced and pressure increases.
Oil is injected into the cylinder to remove the heat of
compression and seal internal clearances. Volume re-
duction and pressure increase continues until the air/oil
mixture trapped in the interlobe cavity by the rotors
passes the discharge port and is released to the oil res-
ervoir (C). Each rotor cavity follows the same “fill–com-
press–discharge” cycle in rapid succession to produce
a discharge air flow that is continuous, smooth and
shock free.
AIR FLOW (FIGURE 5–1, page 31) – Air enters the air
filter and passes through the inlet unloader valve to the
first stage compressor. After first stage compression,
the air/oil mixture passes through the interstage man-
ifold where coolant is injected. The air/oil mixture then
is compressed to the final discharge pressure in the se-
cond stage compressor. After compression, the air/oil
mixture passes into the oil reservoir where most of the
entrained oil is removed by velocity change and im-
pingement and drops back into the reservoir. The air
and remaining oil then passes through the oil separator,
the separated oil is returned to the system through tub-
ing connecting the separator and the first stage com-
pressor. The air passes through the reservoir dis-
charge manifold, minimum pressure/discharge check
valve, and the customer furnished unit shutoff valve if
aftercooled. If water cooled, the aftercooler and mois-
ture separator are between the minimum pressure/dis-
charge check valve and the customer supplied shutoff
valve.
LUBRICATION, COOLING AND SEALING – Oil is
forced by air pressure from the oil reservoir through the
oil cooler, thermostatic mixing valve/oil filter assembly
and is piped to the first stage compressor, second
stage compressor and the interstage manifold. A por-
tion of the oil to the compressors is directed through in-
ternal passages to the bearings, gears and shaft oil
seals. The balance of the oil is injected directly into the