Controlling the gap geometry in an eccentric screw pump

A method for operating a progressive cavity pump comprising a helical rotor, a stator within which the helical rotor is rotatably disposed about a longitudinal axis of the stator, the stator further comprising an inlet, an outlet, and a helical inner wall corresponding to the helical rotor, wherein the helical rotor comprises a shape tapering down toward the outlet or the inlet, and the helical rotor and the stator are disposed relative to each other such that at least one chamber is formed for transporting the liquid, and the chamber is cut off by a constriction between the helical rotor and stator, a drive shaft and a drive motor, wherein the helical rotor is coupled to the drive motor by the drive shaft, and an adjusting device for adjusting a relative axial position of the helical rotor and stator, wherein the adjusting device is adapted to adjust the constriction between the helical rotor and stator,

• wherein the helical rotor is axially displaceably supported and the adjusting device is adapted to axially displace the helical rotor to at least partially adjust the constriction between the helical rotor and stator, and
• wherein a gearbox is disposed between the drive shaft, and the drive motor and the gearbox allows axially displacing the drive shaft, wherein the drive shaft is connected to a drive shaft of the drive motor, and wherein the gearbox is equipped with a gear implemented as a hollow shaft, in which the shaft of the drive motor is displaceable;
• wherein the method comprises the steps of:
• driving the helical rotor via the drive motor for transporting a liquid;
• and
• adjusting the constriction between the helical rotor and stator by axially displacing the helical rotor and stator relative to each other.