Page 4
B − Compressor
FIGURE 3
SCROLL COMPRESSOR
DISCHARGE
SUCTION
All 13ACD units utilize a scroll compressor. The scroll com-
pressor design is simple, efficient and requires few moving
parts. A cutaway diagram of the scroll compressor is shown in
figure 3. The scrolls are located in the top of the compressor
can and the motor is located just below. The oil level is immedi-
ately below the motor.
The scroll is a simple compression concept centered around
the unique spiral shape of the scroll and its inherent properties.
Two identical scrolls are mated together forming concentric
spiral shapes (figure 4). One scroll remains stationary, while
the other is allowed to "orbit" (figure 5). Note that the orbiting
scroll does not rotate or turn but merely orbits the stationary
scroll.
NOTE − During operation, the head of a scroll compressor may
be hot since it is in constant contact with discharge gas.
FIGURE 4
STATIONARY SCROLL
ORBITING SCROLL
DISCHARGE
SUCTION
CROSS−SECTION OF SCROLLS
TIPS SEALED BY
DISCHARGE PRESSURE
DISCHARGE
PRESSURE
The counterclockwise orbiting scroll draws gas into the outer
crescent shaped gas pocket created by the two scrolls (figure 5
− 1). The centrifugal action of the orbiting scroll seals off the
flanks of the scrolls (figure 5 − 2). As the orbiting motion contin-
ues, the gas is forced toward the center of the scroll and the
gas pocket becomes compressed (figure 5 − 3). When the
compressed gas reaches the center, it is discharged vertically
into a chamber and discharge port in the top of the compressor
(figure 4). The discharge pressure forcing down on the top
scroll helps seal off the upper and lower edges (tips) of the
scrolls (figure 4). During a single orbit, several pockets of gas
are compressed simultaneously providing smooth continuous
compression.
The scroll compressor is tolerant to the effects of liquid return. If
liquid enters the scrolls, the orbiting scroll is allowed to separate
from the stationary scroll. The liquid is worked toward the cen-
ter of the scroll and is discharged. If the compressor is re-
placed, conventional Lennox cleanup practices must be used.
1
2
3
4
SUCTION
SUCTION
ORBITING SCROLL
STATIONARY SCROLL
SUCTION
SUCTION
DISCHARGE
SUCTION
INTERMEDIATE PRESSURE
GAS
CRESCENT
SHAPED
GAS POCKET
HIGH PRESSURE GAS
FLANKS SEALED
BY CENTRIFUGAL
FORCE
MOVEMENT OF ORBIT
FIGURE 5
