Membrane for pump, has profiles in its surface in form of waves, folds or grooves, lines of separation between which are arranged so that their direction at specific position is at constant angle to radius passing through that position

摘要

The membrane has profiles (2) in its surface which are in the form of waves, folds or grooves. The lines of separation (8) between these are arranged so that their direction at a specific position is at a constant angle to the radius which passes through that position.