Pumping drive unit

Abstract

A pumping unit is disclosed which alternately applies a positive and a negative pressure, both of given values, to aa drive chamber of an artificial heart. In a first and a second embodiment, air of an elevated pressure which is discharged by an air compressor is fed through a positive pressure accumulator and a positive pressure open/close valve to the drive chamber, and a negative pressure from an air decompressor is fed through a negative pressure accumulator and the negative pressure open/close valve to the drive chamber. Alternating open periods are assigned to the positive and the negative pressure open/close valve. During the open period, each valve is opened and closed in a manner corresponding to the prevailing pressure in the drive chamber so as to maintain the pressure at a constant value. In a third embodiment, a positive pressure regulator valve is interposed between the air compressor and the positive pressure accumulator, and the positive pressure open/close valve is interposed between the positive pressure accumulator and the drive chamber while a negative pressure regulator valve is interposed between the air decompressor and the negative pressure accumulator, and the negative pressure open/close valve is interposed between the negative pressure accumulator and the drive chamber. The positive and the negative pressure open/close valves are opened in an alternate fashion. The positive pressure regulator valve is operated with a given duty cycle which depends on the prevailing pressure from the positive accumulator so that such pressure is maintained at a constant value. The negative pressure regulator valve is operated with a given duty cycle which depends on the prevailing pressure of the negative accumulator so that such pressure is maintained at a given value.