GB2303499A

GB2303499A - Electric machine slot wedge

Info

Publication number: GB2303499A
Application number: GB9615040A
Authority: GB
Inventors: Bernd Halt; Horst Knupling; Stefan Wintzer
Original assignee: STILL GmbH
Current assignee: STILL GmbH
Priority date: 1995-07-20
Filing date: 1996-07-17
Publication date: 1997-02-19
Also published as: DE19526509A1; FR2737059A1; ITMI961051A0; IT1294979B1; GB9615040D0; ITMI961051A1

Description

ELECTRICAL MACHINE 1 2303499 The invention concerns an electrical machine

with a rotor which is rotatable about a rotation axis and has slots disposed at an oblique angle or parallel to the rotation axis in which formed coils formed of profiled wire are laid, the slots being closed in the radial direction towards the surface of the rotor by means of wedges connected positively to the rotor and the voids left in the slots being sealed with resin.

The formed coils are laid or pressed into the slots of the rotor. Each formed coil can consist of a single profiled wire or of a plurality of profiled wires disposed next to one another in the same slot. Likewise, a plurality of layers of formed coils can be disposed one above another in the radial direction in the same slot. Each slot is closed with a wedge or cap at the surface of the rotor. After the formed coil has been laid or pressed into the slot, this wedge is slid into the slot in the longitudinal direction of the slot. Corresponding profiling of the side walls of the slot serves to fix the wedge in the radial direction. The wedge has the task of protecting the formed coils against mechanical damage, and fixing the formed coils within the slot against the centrifugal forces acting when in operation. In order to avoid air gaps inside the slot, and the resulting losses of efficiency, the voids left after insertion of the wedge inside the slot are filled with warmed liquid resin in an immersion-impregnation process. After cooling, the resin provides a durable seal for the voids.

However, in practice a recurrent problem is that not all the voids within the slot are filled with resin. Above all, fine gaps are often not penetrated by resin.

The underlying object of the present invention is to provide an electrical machine of the kind described in which all the voids within the slots are filled with resin.

According to the invention this object is achieved in that the wedges are formed with at least one opening and/or at least one recess in the radial direction.

2 The radial openings or recesses form a connection from the interior of the slots to the surface of the rotor. When the rotor according to the invention is immersed in the bath of liquid resin, the resin penetrates into all the fine gaps within the slots due to capillary forces, while the air located therein can escape through the openings or recesses in the wedges. This ensures that the air gaps left within the rotor are reduced to a minimum.

In the case of electrical machines in which at least two layers of formed coils are laid into the slots and an insulating material, e.g. an insulating film, is disposed between the layers, one advantageous variant of the invention is characterised in that the insulating material is formed with openings and/or recesses extending in the radial direction.

The insulating material serves to ensure insulation between the two layers. The recesses or openings in the insulating material allow radial flow of air and resin, so that when the rotor is immersed in the liquid resin, the radially inner layer of the winding also receives an adequate supply of resin and any air trapped in the area of the radially inner layer can escape.

Further advantages and features of the invention are explained in greater detail with reference to the example shown in the accompanying diagrammatic Figures, in which:

Figure 1 shows the rotor of an electrical machine according to the invention in side view, and Figure 2 shows a partial cross-section of the rotor, the section plane extending across a slot.

Referring now to the drawings, Figure 1 shows the rotor of an electrical machine according to the invention. The rotor is mounted so as to be rotatable about a rotation axis 3 in bearings 1, 2 in a housing (not shown) of the electrical machine. A body 18 of the rotor is formed with slots 4 which are distributed over the entire circumference of the rotor and are disposed at an oblique angle to the rotation axis, and in which the rotor winding 5 formed of profiled wire is laid. In the radial direction the slots 4 are closed with wedges 6. According to the invention these wedges are penetrated by openings 7 and/or provided with 3 recesses 8. When the rotor is impregnated with liquid resin, the resin can enter the voids within the slots 4 at the ends 9 of the slots and through the openings 7 or recesses 8 and can fill all the gaps due to capillary forces. The escape of the air trapped in the slots 4 is also facilitated by the openings 7 or recesses 8.

Figure 2 shows a partial cross-section through the rotor, the section plane extending across a slot 4. An upper (radially outer) layer 10 and a lower (radially inner) layer 11 of formed coils 5 are disposed within the slot. Both the upper layer 10 and the lower layer 11 consist of three profiled wires disposed next to one another. An insulating film 12 is disposed betweenthe upper layer 10 and the lower layer 11. The insulating film 12 is formed with penetrating openings 13. The wedge 6 is connected positively to the body 18 of the rotor by engaging in undercuts formed in the walls of the slot 4 adjacent the open side of the slot 4. The recesses 8 in the lateral edges of the wedge 6 and the openings 13 in the insulating film 12 serve to improve the filling of the voids 14 and gaps 15 within the slot 4 with resin, by allowing trapped air to escape and liquid resin to flow in.

Claims

4 1. An electrical machine with a rotor which is rotatable about a rotation axis and is formed with slots in which formed coils formed of profiled wire are laid, the slots being closed in the radial direction towards the outer surface of the rotor by means of wedges connected positively to the rotor, and the voids left in the slots being sealed with resin, characterised in that the wedges each have at least one opening and/or at least one recess to allow fluid to flow therethrough in the radial direction.
2. An electrical machine according to claim 1, wherein the slots are disposed at an oblique angle or parallel to the rotation axis.
3. An electrical machine according to claim 1 or claim 2, wherein a radially inner and a radiaily outer layer of formed coils are laid in the slots and solid insulating material is disposed between the layers, characterised in that openings andlor recesses extending in the radial direction are formed in the insulating material.
4. An electrical machine according to claim 3, wherein the insulating material is an insulating film.
5. A rotor for an electrical machine according to any preceding claim.
6. An electrical machine substantially as herein described, with reference to Figures 1 and 2 of the accompanying drawings.
7. A rotor for an electrical machine substantially as herein described, with reference to Figures 1 and 2 of the accompanying drawings.