GB2032707A

GB2032707A - A rotor of an electrical generator

Info

Publication number: GB2032707A
Application number: GB7933958A
Authority: GB
Original assignee: Ducellier et Cie
Current assignee: Ducellier et Cie
Priority date: 1979-10-01
Filing date: 1979-10-01
Publication date: 1980-05-08
Also published as: GB2032707B

Abstract

A rotor for an electrical generator has a pair of rotor poles (2, 3) with respective half cores (14, 15) which engage within a hollow central portion of a spool 4 carrying a winding 5; at least one of the half cores has one or more tapered bosses (17) thereon arranged to enter said spool portion by deforming the latter during assembly of the spool and rotor poles, thereby to resist relative rotation of the spool and rotor poles, and the flanges of the spool have projections (7) adjacent their periphery to engage between adjacent claws (2a), also to prevent relative rotation between the spool and the rotor poles. <IMAGE>

Description

SPECIFICATION A rotor of an electrical generator The present invention concerns a rotor for an electrical generator, such as a motor vehicle alternator, comprising two rotor poles with opposed claws and each including a shaped half core engaging a hollow former respectively at either side thereof, the former being of insulating material with an inductor wire wound between the flanges thereof and including projections disposed adjacent the periphery of the claws of each rotor pole in order to locate the former with respect to said rotor pole.

In known rotors of this type, the initially and finally wound ends of the inductor wire are guided respectively by split pins situated at the centre of two diametrically opposed projections on one of the flanges of the former and the finally wound end of the wire is retained by a suitably shaped moulded stud in the region of a projection adjacent to the guiding split pin for that end of the wire.

Experience has shown that although rotors made in this manner give rise to a number of advantages, the former is not rendered completely immobile by the projections and this leads to the creation of vibrations during operation which themselves have the effect of causing breakage of the initially and finally wound wire ends in the region of the split pin or moulded stud.

The object of the present invention is to remedy these drawbacks by improving the retention of the former with respect to the rotor poles.

According to the invention, a rotor for an electrical generator comprises two rotor poles having interdigitated claws and each including a half core, a flanged spool of insulating material having a hollow central portion within which the half cores engage, an excitation winding wound between the spool flanges, projections arranged adjacent to the periphery of the spool flange external surfaces and received between two consecutive claws of each rotor pole in order to position the spool in relation to the rotor poles, and one or more tapered bosses on the periphery of at least one of the half cores and arranged to enter the hollow central portion of the spool by deformation of the latter during assembly of the spool and rotor poles so as to resist rotation of the spool with respect to the rotor poles.

Conveniently, the bosses of tapered form may be constituted by the angles of a frustom of a polygonal pyramid circumscribed about the circular base of the half core of the rotor poles.

The invention will now be described, by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view of one form of the rotor of the invention; Figure 2 is a plan view of one rotor pole of the rotor of Fig. 1, Figure 3 is a cross-sectional view of the rotor pole of Fig. 2 along the line A-A Figure 4 is a cross-sectional view to a larger scale of part of Fig. 1 showing the former and one of the rotor poles, Figure 5 is a cross-sectional view of the former of Figs. 1 to 4 along another plane.

Figure 6 is a plan view of an alternative form of rotor pole, and Figure 7 is a view in cross-section along the line B-B of Fig. 6.

As seen in Fig. 1, the rotor therein shown includes, in known manner, two rotor poles 2 and 3 fast with a drive shaft 1, a former 4, and an inductor wire 5 wound between the flanges 4a and 4b of the former 4. Each rotor pole 2 and 3 is constituted by a disc which has in its central portion one half of a magnetic core, shown respectively at 1 4 and 15, and at its periphery, claws 2 a for the rotor pole 2 and 3a for the rotor pole 3, extending parallel to the axis of rotation of the rotor.

The former 4, made of hard plastics material such as polypropylene, includes on the periphery of each of its flanges 4a and 4b, outwardly extending projections 7 formed in one piece with the former 4 and in number corresponding to the number of spaces 1 6 between the claws of the rotor poles 2 and 3.

These projections have the form of a cup in order to fit into the rounded space between two adjacent claws and effect the rotary connection and positioning of the former 4 with respect to the rotor poles 2 and 3.

As seen in Fig. 5, two pins 9 and 13, preferably cylindrical, are formed also in one piece in the cavity of two diametrically opposed projections 7 on a same flange of the former 4. These projections 9 and 1 3 have a length at least equal to the thickness of the disc of the rotor pole 3 and have a longitudinal slot (not shown) through which extend the ends of the inductor wire 5. The projection 9 is used for the passage of the initially wound wire 8 and the projection 1 3 for that of the finally wound wire 6.

Each rotor pole 2 and 3 includes on the periphery of the half core 1 4 and 1 5 a plurality of bosses 1 7 of tapered form obtained during the same manufacturing operation in one piece with the rotor poles 2 and 3 and in number equal to the number of claws on each pole.

The bosses 1 7 are disposed, in the present embodiment opposite to the spaces 1 6 between claws at the base of the half cores 1 4 and 15 and their outermost points 1 7a merge with the surfaces 14a and 15a of the half cores 14 and 15.

The outermost points 1 7a of the bosses 17 are at a distance hfrom the base 15b of the half core 1 5 or 1 4 b of the half core 14 equal, at the most, to the height hlof the projections 7 so that when the former 4 is engaged, said bosses 1 7 of tapered form engage wholly within the hollow cylindrical portion 4cso as to deform the latter and immobilise it in rotation with respect to the rotor poles 2 and 3 when the projections 7 are engaged in the spaces 16 between the claws of the rotor poles 2 and 3.

In another embodiment shown in Figs. 6 and 7, the bosses of tapered form are constituted by the angles 1 8 of a frustom of a hexagonal pyramid 9, and circumscribed about the circular base 20 of the half core 21 of the rotor pole 22.

Claims

1. A rotor for an electrical generator, comprising two rotor poles having interdigitated claws and each including a half core, a flanged spool of insulating material having a hollow central portion within which the half cores engage, an excitation winding wound between the spool flanges, projections arranged adjacent to the periphery of the spool flange external surfaces and received between two consecutive claws of each rotor pole in order to position the spool in relation to the rotor poles, and one or more tapered bosses on the periphery of at least one of the half cores and arranged to enter the hollow central portion of the spool by deformation of the latter during assembly of the spool and rotor poles so as to resist rotation of the spool with respect to the rotor poles.

2. A rotor according to claim 1, wherein the outermost points of the bosses of tapered form merge with the outer surface of the half core at a distance from the spool flange engaging surface of the half core which is at the most equal to the height of the projections, so that when the spool and rotor poles are assembied, the bosses can only enter the hollow central portion of the spool when the projections engage between the claws of the rotor poles.

3. A rotor according to claim 1 or claim 2 wherein the bosses of tapered form are constituted by the angles of a frustom of a polygonal pyramid circumscribed about the circular base of the half core.

4. A rotor for an electrical generator, substantially as hereinbefore described with reference to Figs. 1 to 5 or Figs. 6 and 7 of the accompanying drawings.

5. An electrical generator incorporating a rotor according to any one of Claims 1 to 4.