Slot sealing compound, slot seal, and method for producing a slot seal

Abstract

The invention relates to a slot sealing compound (7) for an electrical machine that comprises at least one slot (2) with a slot opening (5) for receiving an electrical conductor arrangement (3). Said slot sealing compound (7) contains a magnetic filler material, particularly a soft-magnetic filler material, and a reactive resin mixture that comprises at least one resin component. In the interests of improving storage stability for said slot sealing compound (7), the components thereof are selected to be suitable for cationic polymerisation. A catalyst, provided to accelerate the cationic polymerisation of said reactive resin mixture, is also added to said slot sealing compound (7).

Claims

1. A slot sealing compound for filling into a slot opening of an electric machine that accommodates an electric conductor arrangement for the electric machine, comprising: a reactive resin mixture containing at least one resin component; a catalyst configured to accelerate a cationic polymerization of the reactive resin mixture; a magnetic filler material; and an additive configured to bind or inhibit the catalyst at a temperature of up to 45° C. so as to prevent the catalyst from accelerating the cationic polymerization of the reactive resin mixture and thereby render the slot sealing compound storage stable up to a temperature of 45° C., said additive is selected from the group consisting of aluminum trihydrate, magnesium hydroxide and their salts.

2. The slot sealing compound of claim 1, wherein the magnetic filler material is a soft-magnetic filler material.

3. The slot sealing compound of claim 1, wherein the catalyst is at least one substance selected from the group consisting of organic ammonium salt, sulphonium salt, phosphonium salt, and imidazolium salt.

4. The slot sealing compound of claim 1, wherein the catalyst has a percentage by weight of at most 5% by weight.

5. The slot sealing compound of claim 1, wherein the catalyst has a percentage by weight of at most 1% by weight of the reactive resin mixture.

6. The slot sealing compound of claim 1, wherein the resin component is an epoxy resin.

7. The slot sealing compound of claim 1, further comprising organic and/or inorganic nanoparticles.

8. The slot sealing compound of claim 1, having a glass transition temperature of at least 180° C.

9. The slot sealing compound of claim 1, wherein the magnetic filler material has a percentage by weight, which amounts to at least 85% by weight.

10. The slot sealing compound of claim 1, wherein the magnetic filler material is present in the form of bimodal to multimodal particle size distributions.

11. The slot sealing compound of claim 1, having a storage stability of several days at a temperature of up to 45° and/or an air humidity of more than 50%.

12. A slot seal, comprising the slot sealing compound of claim 1.

13. A method for producing a slot seal in an electric machine, comprising, mixing a reactive resin mixture, comprising at least one resin component together with a magnetic filler material and a catalyst to accelerate a cationic polymerization of the reactive resin mixture and an additive selected from the group consisting of aluminum trihydrate, magnesium hydroxide and their salts to form a slot sealing compound as a slot seal for an electric machine, the slot sealing compound being storage stable up to a temperature of 45° C., introducing a conductor arrangement into a slot of the electric machine, placing the slot sealing compound to seal a seal opening of the slot; and thereafter subjecting the slot sealing compound to a heat treatment initiating the cationic polymerization of the slot sealing compound.

14. The method of claim 13, further comprising hardening initially only a surface of the slot sealing compound through heat treatment to realize a superficial hardening.

15. The method of claim 13, further comprising hardening initially only a surface of the slot sealing compound through UV treatment to realize a superficial hardening.

16. The method of claim 13, wherein the polymerization of the slot sealing compound takes place at a hardening temperature from about 70° C.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) An exemplary embodiment of the invention is explained in more detail on the basis of a drawing. The sole FIGURE here shows an exemplary embodiment of a stator of an electric machine having a magnetic slot seal.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(2) An exemplary embodiment of a stator 1 of an electric machine is shown in a partial cross-section in the FIGURE. The stator 1 comprises a slot 2, in which an electric conductor arrangement 3 is positioned. The conductor arrangement 3 (only shown schematically) can be embodied as an electrical individual conductor or also as a combination of a number of electrical sub-conductors. It is surrounded with an electrical insulation 4 and is part of a coil winding of the stator 1. The slot 2 and the conductor arrangement 3 can basically also be provided in a rotor of the electric machine instead of in the stator 1.

(3) In the region of a slot opening 5, a slot seal 6 is arranged within the slot 2. The slot seal is embodied from a slot sealing compound 7, which contains a soft-magnetic filler material and a reactive resin mixture. The reactive resin mixture is composed at least from a resin component, in the exemplary embodiment shown an epoxy resin, and a catalyst for a cationic polymerization of the epoxy resin. The slot sealing compound 7 can also contain organic and/or inorganic nanoparticles and fibrous filler materials.

(4) The proportion of the magnetic filler material in the slot sealing compound 7 amounts to at least 85% by weight. The proportion of the catalyst in the reactive resin mixture amounts at most to 5% by weight, in particular the percentage by weight of the catalyst amounts to less than 1% by weight of the reactive resin mixture.

(5) The components of the slot sealing compound 7 form a ready-mix, which is storage stable at room temperature and/or at the same time as a high air humidity. Even with a raised air temperature, e.g. of 45° C., the ready-mix is storage stable for a number of days to weeks and its components do not react disadvantageously with one another in respect of processing and final properties. The ready mix can thus be stored and transported during periods of several days or weeks. In the exemplary embodiment shown, the slot sealing compound is firstly treated with UV light at the site of application, once it is inserted into the slot opening 5, so that the surface of the slot sealing compound is hardened. The slot sealing compound 7 is then subjected to a heat treatment, in particular with a hardening temperature of 70° C. or higher, so that the lower layers of the slot sealing compound 7 thus also polymerize.

(6) A slot sealing compound 7 manufactured in this way is characterized by a high chemical resistance, by a high temperature resistance and mechanical stability, by a high magnetic permeability on account of the high proportion of magnetic filler material. By virtue of its composition, the slot sealing compound 7 has in particular a glass transition temperature of more than 180° C. The area of application of the slot seal 6 lies here in the temperature class F or greater, i.e. during operation of the electric machine, a temperature of in particular 155° C. can be reached and if necessary exceeded. Moreover, the slot sealing compound does not contain any toxic components that are legally required to be labeled.