Hitachi YUTAKI S80 Series - Page 32

2. Features and benets
TCGB0075 rev.0 - 11/2012
32
Protection against liquid return
When the compressor is at rest, the moving scroll rests on the casing. When the compressor starts to run, the pressure in
the chamber under the scroll builds up through two bleed holes in the medium pressure section of the compression stroke.
This pressure then forces the scroll up against the housing and seals the compression chamber. If liquid returns to the
compressor, the resulting increase in pressure forces the scroll downwards, breaking the seal and allowing the liquid to
pass back into the compressor body, where it will boil off due to the higher temperature.
Hitachi Air Conditioning Product SA 2008.
1. Comercial information
MAIN FEATURES
Suction inlet
Gas outlet
Fixed scroll
Moving scroll
Housing
Medium pressure
chamber
“Oldham ring”
Shaft
Oilway
Optimized design of stator coils
The design of the stator coils positioned to optimize the magnetic eld signicantly reduce heat losses, and increase the
motor’s efciency at low speeds.
Compressor efficiency
New stator coil design
Current model
Efficiency
rpm
DC compressor with neodymium magnet
The use of a DC compressor with neodymium magnets in the rotor improves the performance at around the 30-40Hz range
where the operation time of the inverter compressor is longest. Additionally, to suppress electromagnetic noise interference
and achieve low noise, the rotor has been divided into two parts and the electric pole displaced.
Characteristics at low speed, which affect the annual running cost, have been signicantly improved.
High efficiency
motor (%)
DC motor
AC motor
rpm
Rotor shape
optimized
Neodymium
magnet
Reduction
of the typical
electromagnetic
noise of the DC
compressor.
Increased
efficiency in
the complete
range of
rpms used
Compressor rotor