Elevator motor with damper winding

Abstract: Damper winding (13) for an elevator motor provided with permanent magnets (14). The damper winding consists of frames (16) surrounding each permanent magnet (14). Each one of the frames is electrically connected to the adjacent frame (16) or the frames are integrated together. The damper winding (13) can be used as a jig for positioning the magnets when these are being fixed to the rotor disc (6). In one of the embodiments, the magnets and damper winding are fixed to the rotor disc by a form-fit interlocking arrangement.

Description: The present invention relates to an elevator motor with damper winding as defined in the preamble of claim 7. Damper windings are typically shorted windings which are used in electric machines for various purposes, such as improving the running characteristics of a motor when affected by transients, improving a motor's starting characteristics and improving e.g. a synchronous motor's ability to withstand a pulsatile load. A further purpose is to reduce the noise level of a motor, which is particularly important in the case of elevator motors. Damper windings may be placed in the same slots with the motor windings, they may be passed through the magnetic poles or they may be placed in slots on the surface of the magnetic poles. In a motor provided with permanent magnets, passing the damper winding through the magnet is difficult, and it is likewise difficult to make slots on the surface of the magnet. EP-A 228 873 describes in figures 15 and 16 a permanent magnet motor with a planar air gap perpendicular to the motor shaft. The permanent magnets are fitted in the rotor in an aluminum cage with could act as a damper winding. Figure 4b of US 5,216,339 discloses a planar disc rotor perpendicular to the motor shaft comprising permanent magnets which are fixed in a steel shell and which are mounted with aluminum cage plates formfitting on their outer and inner edges to the rotor. Although this solution is more space saving than the aforementioned solution it is rather complicated as it needs the shells, the permanent magnet cage plates as well as rivets to fix the cage plates of opposites sites of the rotor to each other and to the surface of the rotor. The object of the present invention is to propose a new and advantageous solution for the placement of a damper winding in a motor provided with permanent magnets, wherein the motor has a discoidal rotor and a planar air gap oriented in a direction perpendicular to the motor shaft. To achieve the objects stated above, the invention is characterized by a method according to claim 1 and an elevator motor according to claim 7. Preferred embodiments of the invention are characterized by the features presented in the corresponding sub claims. The invention provides the advantage that the damper winding is of a simple construction and its manufacturing costs are low. It is used as a mounting jig when the permanent magnets are being mounted. The invention further provides a way to secure the permanent magnets on the rotor, in other words, the damper winding can be used to achieve form-fit interlocking of the permanent magnets with the rotor. Fig. 1 shows where the damper winding of the invention is located in the cross-section of an elevator motor, Fig. 2 presents a damper winding in front view, Fig. 3 presents part of a front view of a damper winding as provided by the invention, Fig.4 presents a cross-section of a damper winding of Fig.3, and Fig.5 presents a cross-section of a damper winding of a second shape. Fig. 1 presents an elevator machinery 1 comprising an elevator motor 2, a brake 3 and a traction sheave 4. The elevator motor 2 comprises a stator 5 and a rotor 6. The stator is a trough-shaped body of revolution with a stator core packet 7 attached to it by means of fixing elements 8. Between the stator and rotor there is a sealing 9. The motor is fixed in place by the stator by means of fixing bolts 10. Bearings 12 are provided between the stator shaft 11 and the rotor 6. The rotor 6 is of a discoidal construction. The traction sheave 4 is attached to the rotor 6. A damper winding 13 as provided by the invention, together with permanent magnets 14, is placed opposite to the stator core packet 7. Between the permanent magnets 14 and the stator core packet 7 is a planar air gap 15, the plane of which is perpendicular to the stator shaft 11. Fig. 2 presents the damper winding as seen from direction A in Fig. 1. The damper winding 13 consists of frames 16 made of non-magnetic, electrically conductive material, surrounding each permanent magnet 14. The plane of the frames 16 is substantially parallel to the plane of the air gap 15 of the motor 2. Each frame is in electric contact with the adjacent frame so that one side 17 of each frame is connected to one side 18 of the adjacent frame 16 of a permanent magnet. The damper winding can be manufactured by making it from separate frames 16 or by integrating the frames 16 in a single structure to form an integrated circular ring. Separate frames 16 can advantageously be manufactured e.g. from aluminium by extruding. Fig. 3 presents the damper winding 13 as seen from the same direction A as in Fig. 2, wherein the damper winding is mounted in a slot 19 in the rotor disc. Fig. 4 presents a cross-section of Fig. 3 along line C-C. The rotor 6 is provided with a ring-shaped slot 19 of a dovetail-shaped cross-section. The damper winding has slanting outer sides and the side of the damper winding next to the permanent magnet is also at a slant. By using a damper winding of the shape shown in the figure, it is possible to implement form-fit interlocking of the permanent magnet and damper winding in the slot e.g. as follows: the permanent magnets 14 are placed in the frames of the damper winding 13, the damper winding is placed in the slot, the slot space that remains between the damper winding 13 and the rotor is filled with form-fit interlocking material (20), such as epoxide resin. The damper winding can be secured against rotation in the slot by roughening the surfaces of the slot and magnets or by fixing the damper winding to the slot with a screw, spline or the like. Fig. 5 illustrates another way of fixing the damper winding in a slot 19a on the rotor disc 6. The damper winding 13 together with the permanent magnet 14 is fastened in the slot 19a by working the surfaces 23-25 between the damper winding 13 and the slot 19a and between the damper winding 13 and the permanent magnet 14 to a suitable roughness, preferably a roughness required for close slide fit, and then pressing the damper winding 13 together with the permanent magnets 14 into the slot 19a. The corners 26-29 of the damper winding 13 that lie against the bottom of the slot are bevelled or rounded. As the damper winding is made of a rather soft kind of material, such as aluminium, bevelling is needed because pressing the winding into the slot may cause a burr ro be raised off the winding. The bevelling prevents the formation of a burr. A bevelling can be made on the magnet as well, or both on the damper winding and the magnet. It is obvious to a person skilled in the art that the embodiments of the invention are not restricted to the examples described above, but that they may instead be varied in the scope of the following claims.

Claims: Method for producing an elevator motor (2) with a damper winding (13) comprising a stator (5) and a discoidal rotor (6) with a planar air gap (15) between them, the plane of said air gap being substantially perpendicular to the shaft (11) of the elevator motor (2), the motor being provided with permanent magnets (14) attached to the rotor (6), the damper winding (13) consisting of frames (16 ) made of non-magnetic, electrically conductive material, surrounding each permanent magnet (14), said frames being laid around the permanent magnets (14) in a plane substantially parallel to the plane of the air gap (15), whereby the shape of the damper winding is substantially that of a circular ring and the damper winding is used as a mounting jig when the permanent magnets are being mounted, and the damper winding (13) together with the permanent magnets (14) is fixed in a slot (19a) in the rotor disc (6) by working the surfaces (22,23,24,25) between the damper winding (13) and the slot (19a) and between the damper winding (13) and the permanent magnet (14) to a suitable roughness, preferably a roughness required for close slide fit, and then pressing the damper winding (13) together with the permanent magnets (14) into the slot (19a). Method for producing an elevator motor as defined in claim 1, characterized in that at least one side (17,18) of each frame (16) is made to electrically contact an adjacent frame (16) of a permanent magnet. Method for producing an elevator motor as defined in claim 2, characterized in that the electric contact is implemented by integrating the adjacent sides (17,18) of adjacent frames (16) of permanent magnets (14) into a single structure. Method for producing an elevator motor as defined in any one of the precedent claims, characterized in that the corners (26-29) of the damper winding (13) or permanent magnet that lie against the bottom of the slot (19a) are bevelled or rounded. Elevator motor (2) with a damper winding (13) comprising a stator (5) and a discoidal rotor (6) with a planar air gap (15) between them, the plane of said air gap being substantially perpendicular to the shaft (11) of the elevator motor (2), the motor being provided with permanent magnets (14) attached to the rotor (6), whereby the shape of the damper winding is substantially that of a circular ring the damper winding (13) consists of frames (16) made of non-magnetic, electrically conductive material, surrounding each permanent magnet (14), said frames being laid around the permanent magnets (14) in a plane substantially parallel to the plane of the air gap (15), and said damper winding (13) together with the permanent magnets (14) being provided in a slot (19a) of the rotor, characterized in that the damper winding (13) is provided as a jig for positioning the permanent magnets (14) and in that the surfaces (22, 23, 24, 25) between the damper winding (13) and the slot (19a) and between the damper winding (13) and the permanent magnet are provided with a suitable roughness, preferably a roughness required for close slide fit. Elevator motor as defined in claim 5, characterized in that the corners (26-29) of the damper winding (13) or permanent magnet that lie against the bottom of the slot (19a) are bevelled or rounded.

Inventors: AULANKO ESKO, HAKALA HARRI, MUSTALAHTI JORMA, AULANKO, ESKO, HAKALA, HARRI, MUSTALAHTI, JORMA
Applicants: KONE CORP, KONE CORPORATION
Application year: 1996
Main classification: H02K1
IPC codes: H02K3, H02K21, H02K1, B66B1