Bearings; Oil Reclaim System; Primary Oil Recovery Mode - Carrier AquaEdge 19XR series Start-Up, Operation And Maintenance Instructions Manual

During the chiller start-up, the oil pump is energized and
provides 40 seconds of lubrication to the bearings after pres-
sure is verified before starting the compressor. During shut-
down, the oil pump runs for 60 seconds to ensure lubrication as
the compressor coasts to a stop. The oil pump can also be ener-
gized for testing purposes by using the Controls Test.
Ramp loading can be adjusted to help to slow the rate of
guide vane opening to minimize oil foaming at start-up. If the
guide vanes open quickly, the sudden drop in suction pressure
can cause any refrigerant in the oil to flash. The resulting oil
foam cannot be pumped efficiently; therefore, oil pressure falls
off and lubrication is poor. If oil pressure falls below 15 psid
(103 kPad) differential, the PIC II controls will shut down the
compressor.
When the oil pump is not running and the oil heater remains
energized for 30 minutes, the oil pump will be started and will
run for 30 seconds to evenly distribute the heat in the oil
system.
There are three pump-filter configurations. The original
vane pump, in which the oil filter is contained in the pump
housing, followed by the vane pump with the oil filter being
external in the oil piping between the oil pump and the oil cool-
er. The third configuration is the gerotor pump, also with the
external oil filter.
A gerotor pump has two rotors, one is inside the other and
their center points are offset with respect to each other. This
type of pump provides a smooth continuous flow. It is also qui-
eter than other designs.
The gerotor pump can be most easily identified by the exter-
nal location of the oil pressure regulator. The regulator is
located on the bottom of the pump pointing horizontally to the
left. See Fig. 8.
The 19XR compressor assemblies include
Bearings —
four radial bearings and four thrust bearings. The low speed
shaft assembly is supported by two journal bearings located be-
tween the motor rotor and the bull gear. The bearing closer to
7
the rotor includes a babbitted thrust face which opposes the
normal axial forces which tend to pull the assembly towards
the transmission. The bearing closer to the bull gear includes a
smaller babbitted thrust face, designed to handle counterthrust
forces.
high speed shaft assembly is supported by two journal bearings
located at the transmission end and mid-span, behind the laby-
rinth seal. The transmission side of the midspan bearing also
contains a tilting shoe type thrust bearing which opposes the
main axial forces tending to pull the impeller towards the suc-
tion end. The impeller side face of the midspan bearing in-
cludes a babbitted thrust face, designed to handle counterthrust
forces.
the high speed shaft assembly has been redesigned to utilize
rolling element bearings (radial and thrust). Machines employ-
ing the rolling element bearings can be expected to have higher
oil pressure and thrust bearing temperatures than those com-
pressors using the alternate bearing design.
Oil Reclaim System —
oil lost from the compressor housing back to the oil reservoir
by recovering the oil from 2 areas on the chiller. The guide
vane housing is the primary area of recovery. Oil is also recov-
ered by skimming it from the operating refrigerant level in the
cooler vessel.
PRIMARY OIL RECOVERY MODE — Oil is normally re-
covered through the guide vane housing on the chiller. This is
possible because oil is normally entrained with refrigerant in
the chiller. As the compressor pulls the refrigerant up from the
cooler into the guide vane housing to be compressed, the oil
normally drops out at this point and falls to the bottom of the
guide vane housing where it accumulates. Using discharge gas
pressure to power an eductor, the oil is drawn from the housing
and is discharged into the oil reservoir.
4
5
6
Fig. 8 — Gerotor Oil Pump
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For compressors equipped with hydrodynamic bearings, the
For compressors equipped with rolling element bearings,
The oil reclaim system returns
1. GERATOR OIL PUMP
2. ISOLATION VALVE
3. OIL PRESSURE REGULATOR VALVE
4. OIL SUMP PRESSURE TRANSDUCER
5. OIL SUMP DRAIN
6. BEARING TEMPERATURE SENSOR TERMINAL BLOCK
7. OIL HEATER
1
3
2
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