FLUID DISPLACEMENT UNIT

摘要

The invention relates to a positive fluid displacement unit (11, 12) comprising positive displacement ports (50) which are arranged in a circle and are associated with switching ports (55) which allow the passage of fluid between one of the positive displacement ports (50) and the associated switching port (55). To reduce the tonality the switching ports (55) are non-periodically circumferentially offset relative to the positive displacement ports (50) in a defined random pattern so that during operation of the positive displacement unit (11, 12) the tonality is effectively reduced with a relatively small variation range.