Abstract: A novel combined scroll compressor profile is proposed. It consists of some similar profile units and each unit includes a large arc, a small arc and a straight line. So the profile is named as arc-arc-line unit combined profile. The basic geometrical theory of the profile is established. The working chamber volume is derived and its change rule is studied. A prototype of scroll compressor with the arc-arc-line unit combined profile for automotive air conditioner is developed and its performance at variable speed is tested. The results show that the scroll compressor with arc-arc-line unit combined profile, in comparison with the one with the normal circle involute profile, has greater refrigeration quantity and higher coefficient of performance (COP) when they have the same overall dimensions of scroll plate.

Key words: Performance, Scroll compressor, Unit combined profile