Rolling Piston Compressor

Rolling Piston Compressor

In the rolling piston compressor (rotary), the refrigerant is compressed by rotating roller inside the cylinder. The partially surface of roller is always contacting with the wall of the cylinder, because of that rotates eccentrically (off-centre) around a shaft. Meanwhile the blade with mounted spring is also contacting to the roller. These two contacting points will create two sealed areas of volume inside the cylinder. When in the suction process, the intake port will opened and the refrigerant will be sucked into the cylinder. While the roller continues to rotate, the volume of area will getting smaller and refrigerant will be compressed to higher pressure. When in the discharge process, the high-pressure refrigerant will force the exhaust valve to open than exit to compressor.

Because of the suction process and discharge process occupied contiguously at the same time, it will decreases friction and vibration and also prevents the leakage of refrigerant during compression. This gives much efficient operation and more quieter than conventional reciprocating type compressor.

What is Inverter technology?

Inverter is a device which supplies variable frequency of power supply on equipments. Because of the speed of motor is determined by the frequency of the power and the number of poles in stator winding , according to the relation.

RPM = Revolutions per minute
p = Number of poles
f = Frequency
By change the frequency of the voltage applied to the motor, the speed will be changed.

Function of Inverter
The inverter is made up primarily of modules that are each made up of a transistor and diode in combination with each other which inverts the DC energy back to AC.

By switching the inverter-transistor devices on and off many times per half cycle, a AC-similar current waveform is approximated. At the same time we can input variable frequency that determined by system requirement.

So it is possible that we can control the speed of motor by changing frequency by inverter technology. That is to say, in the situation of Xpressar system, the temperature of CPU can be maintain at some level we want by it's PWM signal that output to the inverter module of driver board.

Why use DC motor ?
First of all, we need to know what's the difference between the DC & AC Motor.
¡¾The AC Motor¡¿:

1. Current goes through the coil on the stator and the rotating magnetic field is generated.
2. Being induced by the rotating magnetic field, induced current is generated on the rotor (squirrel cage).
3. According to the interaction force between current and magnetic field, the squirrel on which the induced current goes through turns around.

¡¾The DC Motor¡¿:

The biggest and only difference is that rotor is made of permanent magnet, but the principle of the operation is completely different from that of an AC motor..

1. Current goes through the coil on the stator and rotating magnetic field is generated (same as AC)
2. By the interaction of the pole of the magnet, rotor will rotate.

Advantage of DC Motor:
- Less loss and better efficiency than AC motor, because of no motor slip & no induced current loss.
- Less noise than AC motor, because there is no induction effect between stator and rotor.
- Low friction loss , because there is no brush in the motor.

In order to attain better efficiency, it will be reduce the compressor speed, than reduce energy consumption when In partial load conditions. DC motor has been known as much more efficient motor than AC, and its efficiency is roughly double compared to AC. (it means energy consumption becomes half at the same condition.)

In conclusion, DC Inverter type compressor is a good solution for reducing energy consumption, this is so called ¡°Eco-Friendly¡± technology.