Page 12
C−Cooling Components
FIGURE 9
SCROLL COMPRESSOR
DISCHARGE
SUCTION
The scroll compressor design is simple, efficient and re-
quires few moving parts. A cutaway diagram of the scroll
compressor is shown in figure 9. The scrolls are located in
the top of the compressor can and the motor is located in
the bottom of the compressor can. 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 form-
ing concentric spiral shapes (figure 10). One scroll remains
stationary, while the other is allowed to "orbit" (figure 11).
Note that the orbiting scroll does not rotate or turn but mere-
ly orbits the stationary scroll.
NOTE − The head of a scroll compressor may be hot since it
is in constant contact with discharge gas.
FIGURE 10
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 (fig-
ure (figure 11 − 1). The centrifugal action of the orbiting scroll
seals off the flanks of the scrolls (figure 11 − 2). As the orbiting
motion continues, the gas is forced toward the center of the
scroll and the gas pocket becomes compressed (figure 11 −
3). When the compressed gas reaches the center, it is dis-
charged vertically into a chamber and discharge port in the
top of the compressor (figure 9). The discharge pressure
forcing down on the top scroll helps seal off the upper and
lower edges (tips) of the scrolls (figure 10). 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 re-
turn. If liquid enters the scrolls, the orbiting scroll is allowed
to separate from the stationary scroll. Continued slugging of
liquid will cause damage to the scroll and replacement will
be necessary. The liquid is worked toward the center of the
scroll and is discharged. If the compressor is replaced, con-
ventional Lennox cleanup practices must be used.
FIGURE 11
1
SUCTION
SUCTION
ORBITING
SCROLL
STATIONARY
SCROLL
2
SUCTION
INTERMEDIATE PRESSURE
GAS
CRECENT SHAPED
GAS POCKET
FLANKS SEALED
BY CENTRIFUGAL FORCE
MOVEMENT OF ORBIT
3
SUCTION
HIGH PRESSURE GAS
4
SUCTION
DISCHARGE
