Rotodynamic pump with spherical bearing

A canned pump-motor unit for increasing the pressure of a flux of liquid, whose motor has a stator and a rotor separated by a spherical magnetic cap, the rotor forming a rotating unit around an axis of rotation with an impeller which separates the pressure region from a suction region of the pump part of said pump motor unit, said rotating unit being supported by a spherical bearing consisting of a ball having a radius and a bearing cap, the ball being mounted on a stationary pedestal, the bearing cap forming part of the rotor-impeller-unit and riding on a surface of the ball, characterized in that the rotor impeller unit (8,10) is located between the pressure region (16a) and the suction region (15a), said bearing cap (9) having a slot shaped channel (19,30) defined by two wide and two narrow walls, said channel extending from one axial end of said bearing cap (9) to the other, the two wide walls of said channel (19,30) having a substantially longer radial extension than the radius of the ball (6), said wide walls following essentially radially aligned planes running parallel to the axis of rotation, and one of the two narrow walls of said channel running parallel to said axis of rotation at a distance which is considerably larger than the radius of the ball (6), a part of said channel which is defined by said narrow wall and adjacent parts of the two longer walls forming an aperture together with the surface of the ball (6), to cause considerable back flow of the liquid conveyed, created by the pressure of the pump, from the pressure region (16a) to the suction region (15a).