TH40894A - An electric motor that uses a permanent magnet field - Google Patents

Abstract

DC60 (12/04/48) In an electric motor consisting of a number of permanent magnets (46) which surround the armature of the motor (52) for supplying field flux to the armature, a cylindrical magnetic cover (47) is fitted onto the inner circumferential surface defined by the permanent magnets to protect the permanent magnets from chipping and other damage. The magnetic cover is also provided with radial flanges (47b) in which pilot holes (47c) are made so that the adjusting bolts (48) which are driven axially inside the motor housing may be satisfactorily guided when they are inserted from one end of the motor housing to the other end of the shaft. Ideally, to better guide the bolts, each pilot hole may be provided with a cylindrical pilot hub (50,51) which may be created by polishing the surface of a sheet of metal or by cutting and raising a portion of the flange material. In an electric motor consisting of a number of permanent magnets (46) surrounding the motor armature (52) for supplying field flux to the armature, a cylindrical magnetic cover (47) is fitted onto the inner circumferential surface defined by the permanent magnets to protect the permanent magnets from chipping and other damage. The magnetic cover is also provided with radial flanges (47b) in which pilot holes (47c) are made so that the adjusting bolts (48) which are driven axially inside the motor housing may be satisfactorily guided as they are inserted from one end of the motor housing to the other end. Ideally, to improve bolt guiding, each pilot hole may be provided with a cylindrical pilot hub (50,51) which may be created by polishing a sheet of metal or by cutting and raising a portion of the flange material.

Claims (8)

1. An electric motor, which has the following components: an armature (52) which is supported by rotation in a general cylindrical enclosure (44); a number of permanent magnets (46) which are placed on the inner circumferential surfaces of the enclosure to surround the armature and provide field flux to the armature; and a magnetic cover (47) which has a general cylindrical main body (47a) which is fitted closely to the inner circumferential surfaces defined by the permanent magnets; which magnetic cover also contains a radial range (47b) which has pilot holes (49) for receiving bolts (48) which are passed axially through the enclosure. 2. Electric motors, as per claim 1, where the pilot hole is provided with an axial shoulder ring (50,51) that extends in the direction for passing through the said bolt. 3. Electric motors, as per claim 2, where the 50 mm axial shoulder ring is fabricated by a rough drilling process. 4. The electric motor, according to claim 2, which the axial shoulder ring (51) is to be fabricated by cutting a portion of the material of the said wing and by bending that portion away from the said wing. 5. Electric motors, as per claim 2, where the axial shoulder ring shall have a length at least equal to the pitch of the threads of the said bolt. 6. An electric motor, according to claim 1, through which the said bolt is passed axially through the defined gap (46a) between the opposite edges of the next pair of permanent magnets (46). 7. Electric motors according to claim 1, whose magnetic cover (47) is made of aluminum or aluminum alloy. 8. An electric motor, according to claim 1, whose enclosure shall consist of a main cylindrical body (44) which acts as the yoke of such permanent magnet and a pair of opposing end fittings (11) which close the corresponding ends of the main cylindrical body, and such bolts shall be passed through a hole provided in one of the end fittings and have a free end which shall be screwed into a corresponding threaded hole provided in the other end fitting (12,17). (Clause 8, page 2, figure 6)