GB1595279A

GB1595279A - Slot closures of winding carrying components for electric machines

Info

Publication number: GB1595279A
Application number: GB2061078A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-02-04
Filing date: 1978-05-19
Publication date: 1981-08-12
Also published as: FR2416582A1; DE2804877A1

Description

(54) SEAT CLOSURES OF WINDING CARRYING COMPONENTS FOR ELECTRIC MACHINES (71) We, ROBERT BOSCH GmbH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to slot closures for electrical machines.

The individual windings of electric machines are mounted on winding carrying components, normally the armature, and are accommodated in slots. It is known to close open, or semi-closed slots by means of closure wedges. For this purpose, dovetaillike recesses are incorporated in the open slot and are located in the vicinity of the slot opening, slot wedges of complementary exterior configuration being inserted into the recesses such that the wedges are anchored therein. These slot wedges or closure wedges can be made from sintered iron or an iron powder compound bonded by resins, wherein the magnetic properties can be influenced by the thickness of the material or the proportion of the iron powder components or by the size of the powder particles. The anchoring of the closure wedges in the semi-closed slots is also known and is simpler in that the slot cross section tapers again towards the opening and thus retains the closures inserted into the slots.

The width of the slots in armatures of three-phase-current generators on the one hand influences the field distribution in the air gap and thus should be as small as possible for electro-magnetic reasons and, on the other hand, a large slot width is desirable for reasons of manufacturing technology, so that the winding may be more readily introduced into the slot.

Finally, in connection with large slot widths, it is known to reduce disadvantages, affecting the field pattern, by using slot wedges which have magnetic properties particularly in their edge zones.

In generators for motor vehicles, it is also customary to close individual slots by means of strips of pressboard or paper, or by means of paper cord. Advantages with respect to the thermal conditions of the winding ensue when only some of the slots are closed, since the slot wedges basically limit the cross section available for the cooling air.

The present invention provides a winding carrying component for an electrical machine, having semi-closed slots in which the windings are received and having feromagnetic slot closures whose breadth is larger than the width of the mouth of the semi-closed slots which comprise strips of sheet metal of cylindrical metal rods received in the slots and overlying the windings.

The slot closure of the winding carrying component in accordance with the invention has the advantage that the fluctuations in the magnetic flux caused by the slots in electric machines can be reduced, and their effects on the noise produced can be reduced. It is also possible to optimize the magnetic conditions by the thickness of the sheet metal strips in the case wherein the latter are used.

The invention renders it possible to operate with relatively large widths of; slots of semi-closed construction, thus facilitating the winding of the generator components without having to accept unfavourable field distribution.

In one embodiment, the slot closures are in the form of strips of ferromagnetic sheet metal and thus have only a small thickness compared with the cross section of the slot, so that the flow of cooling air is also not substantially obstructed. Further savings in costs ensue in another embodiment wherein the slot closures are in the form of insulated pieces of iron wire, that is, cylindrical closures of suitable diameter. Overall, the slot closure arrangement of the winding carrying component in accordance with the invention combines low expense with a simple construction and a small expenditure on assembly.

It is particularly advantageous to construct the strip-shaped pieces of material in the form of ferromagnetic strips of sheet metal whose thickness can optimize the magnetic conditions.

The present invention will be further described, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a first embodiment of a semi-closed slot of winding carrying component of an electrical machine, having an inserted strip of iron plate acting as a slot closure, and Figure 2 shows a similar semi-closed slot having an insulated iron wire acting as a slot closure.

The Figures only show the region, under consideration, of a winding carrying component of an electric machine such as a three-phase-current generator, namely a slot 1 between two adjacent teeth 2a and 2b (only partially illustrated), and a slot closure which is inserted into the slot and which is inserted into the slot and which is generally designated 3. The basic idea of the invention is to use strip-shaped or cylindrical ferromagnetic materials as the slot closures in winding carrying components, such as the armatures, of electric machines. Suitable strip-shaped materials are thin strips of ferromagnetic iron plate which close the slots in machines having relatively wide slots, and thus contribute to improving the field pattern in the air gap. The sheet metal strip 4 shown in Figure 1 is curved concavely upwardly and, mounted above the winding assembly (not illustrated in the drawing) fitted in the slot 1, is located adjacent the slot opening where it is held by projecting armature parts Sa and 5b which narrow the slot at its mouth.

This slot configuration is designated "semiclosed slot". The strip 4 of iron plate acting as a slot closure is inserted endwise. Since the inserted strip 4 is relatively thin, the electrical machine is cooled in a satisfactory manner, since the flow of cooling air is not substantially obstructed. On the other hand, the magnetic conditions can be optimized without great expense by suitably choosing thickness of the strip of sheet metal, the improve,ent in the magnetic properties having a particularly favourable effect on the development of noise.

Figure 2 shows that insulated pieces of iron wire, designated 6, of suitable diameter can be used as slot closures instead of the ferromagnetic strips of sheet metal. In the same way as the strips of sheet metal, the pieces of iron wire are introduced into the semi-closed slot and constitute a particularly inexpensive solution.

Since the stray flux in the slots is increased when the slot closures are in the form or strips of sheet metal or pieces of iron wire, it is advantageous for slot closures to this type to be at a defined distance from the crests of the teeth. In the case of sheet metal strips, this can be achieved by providing them with a layer, of appropriate thickness, of non-magnetic materials such as paper or epoxy resin, and pieces of iron wire can be insulated in the same way.

For the purpose of producing slot closures in the form of strips of iron plate in an economic manner, corresponding pieces of sheet metal strip are glued to paper or are glued between two strips of paper. Pieces of sheet metal strips of this type can then be coiled onto a supply roll, preferably with a corresponding anterior curvature which can be obtained by pressure rollers of suitable configuration. The strip is then drawn from this supply roll and, in conformity with the length of the slot, is severed at the point of separation between two strips of sheet metal. This cutting operation ensures that, after the sheet metal strip has been introduced into the slot, the paper strip directed towards the winding prevents damage to the winding insulation. Insertion into the slot is further facilitated by rounding or chamfering the edges of the sheet metal strips. It will be appreciated that the length of the sheet metal strips and the distances between the points of separation in the length of the iron core are adapted to the electrical machine.

WHAT WE CLAIM IS:- 1. . A winding carrying component for an electrical machine. semi-closed slots in which the coil windings are received and having ferromagnctic slot closures whose breadth is larger than the width of the mouth of the semi-closed slots and which comprise strips of sheet metal or cylindrical metal rods received in the slots and overlying the windings.

2. A winding carrying component as claimed in Claim 1, wherein the slot closures are in the form of arcuate strips of sheet metal.

3. A winding carrying component as claimed in Claim 2, wherein the strips of sheet metal are provided with a protective coating for protection against corrosion andl or are coated with a non-magnetic material in order to form a predetermined distance from the crest of the teeth between which the slots are defined.

4. A winding carrying component as claimed in Claim 3 wherein said nonmagnetic material is paper and/or epoxy resin.

5. A winding carrying component as claimed in Claim 1, wherein the slot closures are in the form of insulated pieces of wire.

6. A winding carrying component as

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

It is particularly advantageous to construct the strip-shaped pieces of material in the form of ferromagnetic strips of sheet metal whose thickness can optimize the magnetic conditions.

The present invention will be further described, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a first embodiment of a semi-closed slot of winding carrying component of an electrical machine, having an inserted strip of iron plate acting as a slot closure, and Figure 2 shows a similar semi-closed slot having an insulated iron wire acting as a slot closure.

The Figures only show the region, under consideration, of a winding carrying component of an electric machine such as a three-phase-current generator, namely a slot 1 between two adjacent teeth 2a and 2b (only partially illustrated), and a slot closure which is inserted into the slot and which is inserted into the slot and which is generally designated 3. The basic idea of the invention is to use strip-shaped or cylindrical ferromagnetic materials as the slot closures in winding carrying components, such as the armatures, of electric machines. Suitable strip-shaped materials are thin strips of ferromagnetic iron plate which close the slots in machines having relatively wide slots, and thus contribute to improving the field pattern in the air gap. The sheet metal strip 4 shown in Figure 1 is curved concavely upwardly and, mounted above the winding assembly (not illustrated in the drawing) fitted in the slot 1, is located adjacent the slot opening where it is held by projecting armature parts Sa and 5b which narrow the slot at its mouth.

This slot configuration is designated "semiclosed slot". The strip 4 of iron plate acting as a slot closure is inserted endwise. Since the inserted strip 4 is relatively thin, the electrical machine is cooled in a satisfactory manner, since the flow of cooling air is not substantially obstructed. On the other hand, the magnetic conditions can be optimized without great expense by suitably choosing thickness of the strip of sheet metal, the improve,ent in the magnetic properties having a particularly favourable effect on the development of noise.

Figure 2 shows that insulated pieces of iron wire, designated 6, of suitable diameter can be used as slot closures instead of the ferromagnetic strips of sheet metal. In the same way as the strips of sheet metal, the pieces of iron wire are introduced into the semi-closed slot and constitute a particularly inexpensive solution.

Since the stray flux in the slots is increased when the slot closures are in the form or strips of sheet metal or pieces of iron wire, it is advantageous for slot closures to this type to be at a defined distance from the crests of the teeth. In the case of sheet metal strips, this can be achieved by providing them with a layer, of appropriate thickness, of non-magnetic materials such as paper or epoxy resin, and pieces of iron wire can be insulated in the same way.

For the purpose of producing slot closures in the form of strips of iron plate in an economic manner, corresponding pieces of sheet metal strip are glued to paper or are glued between two strips of paper. Pieces of sheet metal strips of this type can then be coiled onto a supply roll, preferably with a corresponding anterior curvature which can be obtained by pressure rollers of suitable configuration. The strip is then drawn from this supply roll and, in conformity with the length of the slot, is severed at the point of separation between two strips of sheet metal. This cutting operation ensures that, after the sheet metal strip has been introduced into the slot, the paper strip directed towards the winding prevents damage to the winding insulation. Insertion into the slot is further facilitated by rounding or chamfering the edges of the sheet metal strips. It will be appreciated that the length of the sheet metal strips and the distances between the points of separation in the length of the iron core are adapted to the electrical machine.

WHAT WE CLAIM IS:- 1. . A winding carrying component for an electrical machine. semi-closed slots in which the coil windings are received and having ferromagnctic slot closures whose breadth is larger than the width of the mouth of the semi-closed slots and which comprise strips of sheet metal or cylindrical metal rods received in the slots and overlying the windings.
2. A winding carrying component as claimed in Claim 1, wherein the slot closures are in the form of arcuate strips of sheet metal.
3. A winding carrying component as claimed in Claim 2, wherein the strips of sheet metal are provided with a protective coating for protection against corrosion andl or are coated with a non-magnetic material in order to form a predetermined distance from the crest of the teeth between which the slots are defined.
4. A winding carrying component as claimed in Claim 3 wherein said nonmagnetic material is paper and/or epoxy resin.
5. A winding carrying component as claimed in Claim 1, wherein the slot closures are in the form of insulated pieces of wire.
6. A winding carrying component as

claimed in claim 1 or 2, wherein the slot closures are in the form of strips of sheet metal to which a layer of paper is glued to at least one side thereof for the purpose of avoiding damagae to the winding insulation.
7. A winding carrying component as claimed in Claim 6, wherein the corners of the strips of sheet metal are rounded or chamfered in order to facilitate insertion into the groove.
8. A winding carrying component as claimed in any of Claims 1 to 4, 6 and 7, wherein the slot closures are in the form of strip-shaped pieces of sheet metal which are of uniform thickness over their entire length and breadth and have a concave curvature in the transverse direction.
9. A winding. carrying component substantially as hereinbefore described with reference to Figure 1 or 2 of the accompanying drawings.
10. A winding carrying component as claimed in any of Claims 1 to 9 which is the armature of a three-phase-current generator for a motor vehicle.