Hitachi- Scroll Compressors

Scroll Compressors - Technical Features & Benefits

Scroll Compressor

The principal of the scroll compressor was first discovered at the beginning of the twentieth Century, but due to the close manufacturing tolerances needed to ensure an efficient operation and mass production, it was not until the late twentieth Century that their production was made possible.

Hitachi marketed the first vertical scroll compressors for air conditioning applications in 1983 and has since ceased production of piston compressors.

A scroll compressor generally uses two scrolls, one fixed and one orbital. The orbital scroll orbits within the fixed scroll, trapping and compressing the gas, gradually forcing it to the centre of the scroll arrangement where it is discharged.

Hitachi High Pressure Scroll

The above is a cut out diagram of the Hitachi High Pressure Scroll. The compressor consists of only five moving parts:-

1 The Rotor

2 Moving Scroll

3 Oldham’s Ring

4 Roller Bearing

5 Check Valve

The main features of the Scroll compressor are:-

a It has a high pressure casing

b Lubrication by pressure difference

c Pressure controlled tip sealing

Efficiency, Noise & Vibration

Scroll compressors are more efficient than their reciprocating or rotary cousins because of the lack of valves and the continuous gas compression cycle. These characteristics also contribute to the quietness of the scroll compressor. The noise pattern is a high frequency noise and is simple to reduce to a very low level using a wool type insulation jacket.

Acoustic Analysis

Vibration Analysis

The above chart shows a 10 fold reduction in vibration of the scroll compressor against a rotary of the same capacity.

Reliability

A scroll compressor has fewer moving parts than a reciprocating or rotary, which makes it a very reliable compressor and, as such, is used in a wide range of applications. The Hitachi high pressure scroll has five. This makes it a very reliable compressor and as such is used in a wide range of applications.

In summary the scroll compressor is regarded as the industry standard for air conditioning and commercial refrigeration applications, as they are efficient, quiet, and reliable.

Hitachi are pioneers of this technology, producing a wide range of high pressure scroll compressors for all applications.