Patent ID: 6545381
Filing Date: 2003-04-08
Classification: F16C,H02K

Abstract:
A small electric motor comprising:a rotor comprising a permanent magnet (15) and a shaft (1) having a first end provided with a depression (2); an axial bearing (3, 5) and a radial bearing (11) supporting the shaft (1) axially and radially, respectively; a bushing (4) receiving the first end of the shaft (1) and having a running surface (5); wherein the axial bearing (3, 5) comprises a non-magnetic ball (3), wherein the ball (3) is positioned in the depression (2) of the shaft (1) and has a side facing away from the shaft (1) and running against the running surface (5) of the bushing (4); wherein the shaft (1) is magnetically loaded in a direction toward the running surface (5) of the bushing (4) so that the ball (3) is forced against the running surface (5) of the bushing (4); wherein the shaft (1) is comprised of a ferromagnetic material and forms a part of a magnetic circuit of the permanent magnet (15) of the rotor; wherein the ball (3) forms an air gap at the first end of the shaft (1); and wherein an end face of the shaft (1) facing the air gap forms a magnetic pole (6), wherein the magnetic pole (6) attracts magnetic particles (7) in the area of the axial bearing (3, 5) and keeps the magnetic particles (7) away from the running surface (5) to counteract a destruction of the running surface (5) and of the non-magnetic ball (3) by the magnetic particles (7).