| 摘要 |
Two part-annular section rigid magnets (4 and 5) are held within a cylindrical metal casing (1) by means of spacer means (9 and 10) comprising a rigid mild steel insert (9), disposed between two free edges (6 and 7) of the magnets, and an additional spacer in the form of a resiliently deformable "U"-shaped spring (10), which is disposed between another two free edges (28 and 29) of the magnets. The mild steel insert (9) has two oppositely-directed lateral extensions (12) disposed in contact with each of the magnets (4 and 5) and the closed end (11) of the casing (1) to locate the magnets (4 and 5) longitudinally within the casing (1). The insert (9) also has locating means (16) adjacent the open end of the casing (1) for engagement with complementary locating means (15) in an end cap for closing the open end of the casing (1) to locate the end cap angularly, relative to the casing (1) and thereby provide optimal commutation. The complementary locating means (15) may include an electrically conductive member which contacts the insert to provide an earth connection within the end cap. Moreover, the insert (9) serves as a magnetic shunt between the magnets (4 and 5) so that on magnetization of the magnets (4 and 5), the magnetic axis lies in a second plane (8) offset from the longitudinal axis (2) towards the insert (9), thus reducing radial vibration of the rotor (24) and noise during operation. <IMAGE> |
