Patent GB-1296226-A (GB)
IPC: H02K3/24
Filed: 1969-12-22
Abstract: 1296226 Dynamo-electric machines MANUFACTURE DE VILEBREQUINS DE LORETTE MAVILOR SA 22 Dec 1969 [26 Dec 1968] 62460/69 Heading H2A In a dynamo-electric machine, e.g. a motor for driving a machine tool spindle similar to that described in Specification 1,060,628, wherein a hollow rotor 1 of moulded insulating material has windings embedded therein, at least one binding filament wound at an angle to the conductors of the windings is incorporated in the insulating material as reinforcement, the rotor and a magnetic circuit together defining a frusto-conical air gap and being axially adjustable relative to each other. As shown in Fig. 7, filaments 19, 20 are wound on either side of the rotor windings 1b and the internal filament may be reinforced by a further transverse filament (21), Fig. 8 (not shown). This transverse filament may alternate from side-to-side of the windings 1b as shown at 22 in Fig. 9. In another arrangement, Fig. 10, a single filament 23 traverses the windings 1b at intervals and encloses groups of conductors. The filament(s) may comprise cotton, glass or enamelled steel. Fig. 1 shows a D.C. commutator motor in which the rotor 1 is attached to a sleeve 1a, preferably by means of a resilient bush (24), Fig. 15 (not shown), and operates between inner and outer magnetic circuit parts 2, 3 forming a stator. The position of the rotor relative to the stator is adjusted by rotating a ring 8 relative to a ring 7, the ring 8 being axially located on sleeve 1a by washers 11 and the ring 7 being located inside a bearing 10 so as to be rotatable with the sleeve 1a to which it is slidably keyed at 9. Co-operating inclined faces are provided on the rings 7, 8 so that relative rotation produces axial movement of the sleeve 1a and rotor, the rings being clamped in their adjusted position by a collar 13 which draws the rings together when engaged by screws, not shown, passing through ring 7. Alternatively, the rotor may be adjusted by sots of shims (14, 15), Fig. 4 (not shown), mounted around the sleeve la and in abutment with parts having a fixed axial position in relation to the stator. The overall air gap between the stator parts 2, 3 may be adjusted by shims 18, Fig. 5, located between the inner part 2 and the motor frame 4. Inner part 2 may rotate with the rotor in which case the air gap is adjusted simultaneously with the rotor position. Cooling of the motor may be effected by a fan 17 which draws air through apertures in the casing along the air gap and through passages in the inner stator part 2, Fig. 11 (not shown). The fan may be driven by a separate motor, Fig. 13 (not shown). Fig. 18 shows an arrangement for mounting the brushes 30. These are carried in pairs in holders 31 which are slidable between guides 32 on a plate 33 attached to a frame partition by screws 34 which engage elongated apertures 33a in plate 33 permitting angular adjustment of the brushes. On insertion of the holders 31 between the guides 32, pins 35a engage members 35 to establish electrical connection to the brushes. Individual holders may be provided for each brush, Fig. 19 (not shown). The excitation means preferably is carried by the inner stator part and may comprise coils 39, Fig. 20, carried by a cruciform-shaped core 38 with sobient poles 38b. Alternatively, Fig. 22, a tubular coil 41 may surround a cylindrical core 41 formed at opposite ends with radially and axially extending poles 40b which are imbricated. This single coil arrangement may be applied to the external stator part and the coil may be replaced by a permanent magnet.