GB2032196A

GB2032196A - Face Commutator for a Dynamo-electric Machine

Info

Publication number: GB2032196A
Application number: GB7932168A
Authority: GB
Original assignee: Societe de Paris et du Rhone SA
Current assignee: Societe de Paris et du Rhone SA
Priority date: 1978-09-27
Filing date: 1979-09-17
Publication date: 1980-04-30
Also published as: IT1123739B; IN153007B; FR2437709B1; DE2937608A1; FR2437709A1; ES484201A1; DE2937608C2; IT7926026A0; GB2032196B

Abstract

A face commutator for a rotating electrical machine includes a plurality of individual segments 2 mounted on an insulating ring 1 which supports the segments 2 with air insulating gaps therebetween; the segments, ring and a metal socket 11 which provides the bore of the commutator being permanently assembled together by a moulding 13 of insulating material. Each segment 2 has a stud 8 which is secured in a corresponding hole in the ring 1 by splitting or bending, and notches 10 are also provided for connecting wires. <IMAGE>

Description

SPECIFICATION A Frontal Collector for a Rotating Electrical Machine The present invention relates to a frontal collector for a rotating electrical machine, especially but not exclusively a collector, the useful part of which is flat and in the form of a disc perpendicular to the centre line of the electrical machine.

In this field of technology collectors are already well known which are made from extruded copper in which radial grooves are stamped marking out the single segments. The bottom of these grooves is uneven with respect to the useful face of the copper, so that after moulding and machining of the raised points corresponding to the groove, the segments are separate. This has the following effects: Cutting out of the initial copper washer involves a substantial loss of metal.

The radial grooves have a clearance necessitated by the performances of the stamping punches, so that the space between the segments does not have a constant thickness over the whole of the height.

The space of gap between segments cannot be made as fine as would be desirable.

The spaces or gaps between segments are lined with insulating material, which requires the use of special abrasive brushes, or milling in order to clear the spaces between segments.

There is another way of producing collectors which partially overcome these disadvantages and comprises rolling a sort of cut-out track. In this way losses of metal are reduced, and the gaps between segments may have a constant sufficiently fine thickness.

An object of the present invention is to obviate or mitigate the disadvantages exhibited by prior collectors.

According to the present invention there is provided a frontal collector for a rotating electrical machine, including a plurality of segments and an annular insulating mounting support to hold the segments at the time of moulding a body in insulating material, whilst providing between the segments insulating gaps which are constituted at least the part of the segments nearest the active face of the collector by air.

This solution makes use of individial copper segments which may be obtained with a minimum loss of metal, and a method of assembling is provided making it possible to have gaps between the segment offering all the qualities sought, in particular air insulation. The insulating support ensures the angular distribution of the segments and assists in the subsequent mechanical maintenance of these segments.

The individual segments are assembled automatically be swaging on the insulating support, so as to constitute a single-piece subassembly. According to a preferred embodiment, each segment has, projecting from the face opposite the useful or working face, an anchoring stud which may be introduced through one opening of the series of openings made at regular angular intervals in the insulating support.

In accordance with an advantageous embodiment, the insulating support has radial ribs, passing between the aforementioned openings, the thickness of which corresponds to the value of the gap between segments. These radial ribs delimit accommodations in the form of sectors taking each one of the segments, which are in this way positioned exactly. The height of these radial ribs is less than the thickness of the segments, so as to preserve the air insulation. To delimit the accommodations intended for the segments in a better way, the insulating support shall preferably have a tubular central section and an external collar or skirt. The central tubular section shall delimit a central passage which will take, in accordance with another characteristic, a metal socket comprising an annular collar under which one end of the said central tubular section fits.This metal socket, which should be made symmetrically, that is to say with its collar at middistance from its ends, constitutes the finished bore of the collector. It should be noted that the moulded body surrounds both the insulating support, the anchoring studs of the segments, and the said metal socket, thereby ensuring perfect mechanical maintenance of the assembly.

In accordance with a first possibility, the individual segments of the collectors are made by stamping, with a constant thickness, each segment having a notch opening out on its useful face.

In accordance with a second possibility, the individual segments of the collector are made by cutting out then bending, each segment thereby being formed of two parts bent against each other and comprising a notch which is complete open.

In this case, the two aforementioned parts may be of different length, so that each segment has a thick area where the notch is located, and a thinner area sufficient for the electrical function of the collector, where the brushes rub.

In every case, the notches of the segments serve for connecting the wires of the wound rotor of the electrical machine.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which Fig. 1 is a front view of an insulating support alone, intended for a first embodiment of a frontal collector for an electric machine; Fig. 2 is a section through the centre line of this insulating support; Figs. 3, 4 and 5 are respectively a side view with partial sections, a rear and top view of a segment for a collector of this first embodiment; Fig. 6 is a half-section through the centre line of a complete collector in accordance with this first embodiment; Fig. 7 is a front view of the insulating support alone, for a second embodiment of a frontal collector; Fig. 8 is a section passing through the centre line of this insulating support;; Figs. 9, 10, 11 and 12 are a side view, a rear view, bottom and top view, of a segment for this second embodiment; and Fig. 1 3 is a half-section passing through the centre line of a complete collector in accordance with this second embodiment.

A collector in accordance with the first embodiment, shown in Figs. 1 to 6, has an insulating support 1 and conducting segments 2.

Insulating support 1, shown alone in Figs. 1 and 2, has an annular shape with a tubular central section 3, a flat annular web 4 and an external collar or skirt 5. Openings 6, in this case rectangular in shape, are provided at regular angular intervals in annular web 4. Radial ribs, 7 are also formed on one of the faces of web 4 extending between tubular central section 3 and external collar 5, each radial rib 7 passing between two openings 6. Tubular central section 3, external collar 5 and radial ribs 7 delimit a certain number of cells or compartments, each of which serves as accommodation for a segment of the collector. The thickness e of ribs 7 corresponds to the value of the gap between segments, and their height h is less than the thickness d of segments 2 (see Fig. 3).

Each segment 2 made of copper, shown alone in Figs. 3 to 5, is made as a single segment by cold stamping, the advantage of which is to increase the hardness of the copper by workhardening. Segments 2 have an anchoring stud 8, projecting from the face opposite useful face 9. In addition, on the curved external side, segments 2 have a notch 10 opening out on useful face 9 but not opening out on the opposite face. By way of advantage, useful face 9 of each stamped segment 2 again has initials, along its radial edges, chamfers or curved parts 9' and 9 (see Fig.

5) which, at the time of subsequent trimming of the collector will avoid the formation of burrs.

Single segments 2 are installed in the correspondingly shaped compartment formed on insulating support 1, stud 8 of each segment passing through one of opening 6 on the insulating support. Each segment 2 is swaged onto web 4 of the insulating support, by division into two parts and the lateral displacement thereof of its anchoring stud 8, as shown in Fig. 6.

In this way a single-piece sub-assembly is constituted comprising insulating support 1 and segments 2.

This sub-assembly is then introduced into the bottom of an injection mould. A metal socket 11, having an external retaining annular collar 12, is introduced into the central passage of insulating support 1, so that one end of tubular section 3 is embedded under collar 12. The sub-assembly is then moulded into an insulating material 13 to form a substantially cone-shaped assembly.

Figs. 7 to 1 3 illustrate a second embodiment of a collector in accordance with the invention.

Insulating support 1 (Figs. 7 and 8) still consists of a central tubular section 3, an annular web 4 and an external collar or skirt 5, web 4 having alternating openings 6 and radial ribs 7. In this case, however, these ribs 7 start from external collar 5 but terminate before reaching tubular central section 3. Radial ribs 7 delimit accommodations for segments 2, these accommodations having a zone of lesser depth, separated by a circulaishourder 14, near tubular central section 3. In addition this central tubular section 3 has recesses 15 made on the face of each accommodation.

Segments 2 (Figs. 9 to 12) are designed from the same general concept as previously, with an anchoring stud 8 and a notch 10, but in this case they are made by cutting out on a standard press, then by bending, from a metal sheet, the thickness d/2 of which is equal to half the total final thickness d of each segment. One of the two sections bent in this way against each other form useful face 9 of the segment, whilst the other part terminates in stud 8. In the zone in which these two parts are connected, that is to say the bent zones, notch 10 is made, which in this case is completely open.It will be noted again that each segment 2 has an area of maximum thickness d which is accommodated in one of the accommodations in insulating support 1 between two radial ribs 7, and a zone which is less wide d/2, which is accommodated in the zone of lesser thickness of the corresponding accommodation.

To complete the precise indexing of segments 2, each of them is extended, at the end of its finished region, by a cut-out strip 1 6 which connects up with one of recesses 1 5 in central tubular section 3.

Segments 2 introduced into the corresponding accommodations on insulating support 1 are swaged by bending their anchoring studs 8 (see Fig. 13), and the subsequent operations that is the adddition of a central metal socket 11 and the moulding of an insulating body 13, are not modified with respect to the description of the first embodiment.

As is obvious, the invention is not limited to the embodiments of this frontal collector which have been described above as examples; on the contrary it also covers any variants comprising equivalent means. Indeed when notches 10 of segments 2 open out on the side where anchoring stud 8 is located, insulating support 1 may have segment indexing bosses, additional to the notches; the radial separating ribs 7 may then be eliminated.

Claims

1. A frontal collector for a rotating electrical machine, including a plurality of segments and an annular insulating mounting support to hold the segments at the time of moulding a body in insulating material, whilst providing between the segments insulating gaps which are constituted at least the part of the segments nearest the active face of the collector by air.

2. A frontal collector as claimed in claim 1, in which each segment has, projecting from its face opposite its useful face, an anchoring stud capable of being inserted through an opening of a series of openings made at regular intervals in the insulating support.

3. A frontal collector as claimed in claim 2, in which the insulating support has radial ribs which delimit accommodations in the form of sectors each taking one of the segments between said openings of a width corresponding to the gap between segments and a height of less than the depth of the segments.

4. A frontal collector as claimed in any one of claims 1 to 3, in which the insulating support has a central tubular section and an external skirt.

5. A frontal collector as claimed in claim 3 or claim 4, in which the radial ribs on the insulating support extend between the central tubular section and the external collar.

6. A frontal collector as claimed in claim 3 or claim 4, in which the radial ribs on the insulating support start from the external collar and terminate before the central tubular section.

7. A frontal collector as claimed in any one of claims 4 to 6, in which the central tubular section of the insulating support takes a metal socket comprising an annular collar under which one end of the said central tubular section is embedded.

8. A frontal collector as claimed in claim 7, in which the said metal socket is made symmetrically.

9. A frontal collector as claimed in any one of claims 1 to 8, in which each segment is made by stamping, has a constant depth and a notch opening out on its useful face.

10. A frontal collector as claimed in claim 9, in which each stamped segment has along its radial edges, on its useful face, chamfered or curved sections.

11. A frontal collector as claimed in any one of claims 1 to 8, in which each segment is made by cutting out then bending, the resulting segment being formed of two sections bent against each other and including an open notch.

12. A frontal collector as claimed in claim 11, in which said two sections of each segment are different in length, so that each segment has a wide region where the notches are located, and a narrower region.

13. A frontal collector as claimed in any one of claims 4 to 12, in which each segment extends, at its narrowest end, by a strip which connects up with a recess in the central tubular section of the insulating support.

14. A frontal collector as claimed in claim 11, in which the insulating support has segment indexing bosses, in addition to the notches opening out on the segments.

1 5. A frontal collector for a rotating electrical machine substantially as hereinbefore described with reference to Figs. 1 to 6 or Fig. 7 to 13 of the accompanying drawings.

1 6. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.