9.
Air Cycle Machine (ACM)(fig. 1-26).
The ACS serves as the main cooling component of the system. The ACM
mounts on the cooling air fan plenum after the condenser in the bleed
air flow and after the heat exchanger in the cooling air flow (fig.
1-27).
It consists of a curved bladed radial in-flow turbine wheel
mounted on a common shaft with an axial flow 3.5 in. fan.
When the shaft rotates, self-generated air supports the shaft axially
and radially.
When the shaft is at rest, complaint foil bearings
provide axial and radial support (fig. 1-28).
The ACM has two
journal bearings, for radial support, each consisting of five
overlapping foils; and two thrust bearings, each consisting of eight
foils, providing axial support for the shaft.
After assembly,
without the shaft, the journal bearings resemble the iris of a camera
with an opening smaller than the shaft.
When inserting the shaft,
the foils grip the shaft with a preload.
Figure 1-26.
The Air Cycle Machine (ACM).
23
OD1705
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