Hussmann Ingersoll Rand, User Manual

Page: 218 / 346

Mechanical Design 4
Figure 1: IR Impact
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compressor IR4C2397P with Positive Displacement Lubrication
To avoid frequent tripping, the oil pressure switch includes a time delay (usually 90 to 120
seconds) since the compressor starts with refrigerant dissolved in the oil, for example, the
pump’s operation may be temporarily interrupted by vapor bubbles in the suction port.
Enhanced Centrifugal Lubrication for C- Series Compressors
The challenge was to find a simple and reliable system that completely meets or exceeds the
requirements of the pump system described above:
x
Sufficient oil supply of all areas in the compressor that require lubrication
x
Immediate oil supply when the compressor is started
x
Expels dissolved refrigerant
x
Stable operation at all conditions
x
Ability to monitor the oil circuit for lack of lubrication
The solution is an enhanced centrifugal lubrication system as shown in Figure 2, which is
considerably different from common oil splash designs. By means of a centrifuge (1), which in
this case is a specifically shaped “dynamic disk”, the oil is transported out of the oil sump into a
pocket (2) at the housing cover where the outer crankshaft main bearing is located. The shaft
then has a central entrance port (3) from which the oil is taken in and supplied to the areas that
require lubrication. This system is driven by the centrifugal force of the oil in the shaft, which is
carried from the central port to the areas that require lubrication and are radially located further
outside. Due to its low but steady feed pressure, this oil transportation mechanism is exactly
matched to the demand of the slide bearings, which build oil pressure independent of the feed
pressure. A major advantage of this system over the pump-lubricated version is the small side
flow out of the bearings, which significantly reduces the compressor’s oil carry-over (Fig. 3).
Oil Pump