Method for Producing a Rotor Unit

Abstract

The invention pertains to a method for producing a rotor unit or a bearing unit, wherein the rotor unit or bearing unit is respectively realized with a rotor or a bearing housing and a plain bearing bush (20) for the rotatable arrangement of the rotor on a spindle, wherein the plain bearing bush is placed into a mould (21), wherein the rotor or the bearing housing is respectively produced by attaching a polymeric material to the plain bearing bush in the mould by means of a transfer moulding process or injection moulding process, wherein the plain bearing bush is composed of a first bush section (25) and a second bush section (26) that is connected to the first bush section, wherein the bush sections are placed into the mould, and wherein the polymeric material is attached to the bush sections.

Claims

1. A method for producing a rotor unit, wherein the rotor unit is realized with a rotor and a plain bearing bush (20) for the rotatable arrangement of the rotor on a spindle, wherein the plain bearing bush is placed into a mould (21), and wherein the rotor is produced by attaching a polymeric material to the plain bearing bush in the mould by means of a transfer moulding process or injection moulding process, characterized in that the plain bearing bush is composed of a first bush section (25) and a second bush section (26) that is connected to the first bush section, wherein the bush sections are placed into the mould, and wherein the polymeric material is attached to the bush sections.

2. A method for producing a bearing unit, wherein the bearing unit is realized with a bearing housing and a plain bearing bush for the rotatable arrangement of a spindle of a rotor, wherein the plain bearing bush is placed into a mould, and wherein the bearing housing is produced by attaching a polymeric material to the plain bearing bush in the mould by means of a transfer moulding process or injection moulding process, characterized in that the plain bearing bush is composed of a first bush section and a second bush section that is connected to the first bush section, wherein the bush sections are placed into the mould, and wherein the polymeric material is attached to the bush sections.

3. The method according to claim 1, characterized in that first bush section (25) forms a first radial bearing surface (27) on a first axial end (29) of the plain bearing bush (20) and the second bush section (26) forms a second radial bearing surface (28) on a second axial end (30) lying opposite of the first end.

4. The method according to claim 3, characterized in that the first bush section (25) and/or the second bush section (26) are formed with an axial bearing surface (31, 32) on the respective axial ends (29, 30).

5. The method according to claim 1, characterized in that the plain bearing bush comprises a connecting section, by means of which the first bush section and the second bush section are connected to one another.

6. The method according to claim 1, characterized in that the first bush section (25) and/or the second bush section (26) form a connecting section (33), by means of which the first bush section and the second bush section are connected to one another.

7. The method according to claim 5, characterized in that the connecting section (33) is realized with such an inside diameter (34) that a gap (36) is formed with respect to the spindle.

8. The method according to claim 1, characterized in that the plain bearing bush (20) is encased, preferably completely enclosed radially, by the polymeric material.

9. The method according to claim 1, characterized in that a connecting fit (37), which allows a relative motion between the bush sections in the axial direction, is produced between the first bush section (25) and the second bush section (26).

10. The method according to claim 9, characterized in that the connecting fit (37) is designed with an inside diameter (38) and an outside diameter (39) on the bush sections (25, 26), wherein the connecting fit is realized tight with respect to the polymeric material.

11. The method according to claim 1, characterized in that the first bush section (25) and the second bush section (26) are designed and arranged in the mould (21) in such a way that a radial gap (40) is at least sectionally formed between the first bush section and the second bush section, wherein the polymeric material can penetrate into the radial gap during the transfer moulding or injection moulding process.

12. The method according to claim 1, characterized in that a relative motion between the bush sections (25, 26) in the axial direction against respective inner surfaces (22, 23) of the mould (21) is realized by means of an injection pressure during the transfer moulding or injection moulding process.

13. The method according to claim 1, characterized in that the mould (21) is designed with receptacles for a first axial end (29) of the first bush section (25) and a second axial end (30) of the second bush section (26), wherein the bush sections can be inserted into the respective receptacles, and wherein the receptacles seal the axial ends with respect to the polymeric material during the transfer moulding or injection moulding process.

14. The method according to claim 1, characterized in that the rotor or the bearing housing is made of a fiber-reinforced polymeric material.

15. The method according to claim 14, characterized in that a thermosetting polymer, preferably phenolic resin, epoxy resin, polyester resin or polycyclopentadiene resin, or a thermoplastic polymer, preferably polypropylene, polyphenylene sulfide or polyetheretherketone, is used as polymeric material.

16. The method according to claim 1, characterized in that the bush sections (25, 26) are made of carbon, preferably of graphite, graphite with phenolic resin impregnation, a carbonized, graphite-filled phenolic resin compound, fiber-reinforced polymer or ceramic.

17. The method according to claim 16, characterized in that an additional filler in the form of graphite, molybdenum sulfide, tungsten disulfide, polytetrafluoroethylene, glass spheres and/or mineral additives is added to the polymeric material of the bush sections (25, 26).

18. The method according to claim 1, characterized in that the bush sections (25, 26) are made of different materials.

19. The method according to claim 1, characterized in that the first bush section (25) is produced by means of machining and the second bush section (26) is produced by means of a transfer moulding or injection moulding process.

20. The method according to claim 1, characterized in that the plain bearing bush (20) is designed with a length-diameter ratio of 5:1 or greater.

21. The method according to claim 1, characterized in that a permanent magnet or a cage winding of the rotor unit or the bearing unit is placed into the mould (21) and joined with the rotor or the bearing housing in the mould by means of the transfer moulding process or the injection moulding process.

22. A rotor unit for a canned motor, wherein the rotor unit is realized with a rotor and a plain bearing bush (20) for the rotatable arrangement of the rotor on a spindle, and wherein the rotor is produced by attaching a polymeric material to the plain bearing bush in a mould (21) by means of a transfer moulding process or injection moulding process, characterized in that the plain bearing bush is composed of a first bush section (25) and a second bush section (26) that is connected to the first bush section, wherein the polymeric material is attached to the bush sections.

23. A bearing unit for a canned motor, wherein the bearing unit is realized with a bearing housing and a plain bearing bush for the rotatable arrangement of a spindle of a rotor, and wherein the bearing housing is produced by attaching a polymeric material to the plain bearing bush in a mould by means of a transfer moulding process or injection moulding process, characterized in that the plain bearing bush is composed of a first bush section and a second bush section that is connected to the first bush section, wherein the polymeric material is attached to the bush sections.

24. A pump with a rotor unit according to claim 22.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] An embodiment of the invention is described in greater detail below with reference to the attached drawings.

[0035] In these drawings:

[0036] FIG. 1 shows a longitudinal section through a rotor unit according to the prior art; and

[0037] FIG. 2 shows a longitudinal section through a plain bearing bush in a mould.

DETAILED DESCRIPTION

[0038] FIG. 1 shows a rotor unit 10 according to the prior art, wherein the rotor unit 10 is composed of a rotor 11 and a plain bearing bush 12. The rotor 11 consists of a polymeric material, which was attached to the plain bearing bush 12 in a not-shown mould by means of a transfer moulding process or injection moulding process. The rotor 11 forms an impeller 13 and comprises an armature 14, which forms part of a not-shown canned motor for driving the impeller 13. The rotor unit 10 can be placed on a not-shown spindle in order to thereby rotate about the rotational axis 15 of the rotor unit 10. In the process, radial bearing surfaces 16 of the plain bearing bush 12 come in contact with the spindle, wherein an inside diameter 17 of a bearing bore 18 of the plain bearing bush 12 lying between the radial bearing surfaces 16 is larger than an inside diameter 19 of the radial bearing surfaces 16. A gap, which is not visible in this figure, can thereby be formed between the not-shown spindle and the inside diameter 17. The plain bearing bush 12 is produced in one piece by means of a transfer moulding process or injection moulding process, wherein the material of the plain bearing bush 12 differs from the polymeric material of the rotor 11.

[0039] FIG. 2 shows a longitudinal section through a plain bearing bush 20 in a mould 21. The plain bearing bush 20 can be encased with a polymeric material in the mould 21, for example in order to produce the rotor shown in FIG. 1. The schematically indicated mould 21 has opposite inner surfaces 22 and 23 and comprises a mandrel 24, on which the plain bearing bush 20 is placed. The plain bearing bush 20 is composed of a first bush section 25 and a second bush section 26, wherein the first bush section 25 is connected to the second bush section 26. In this case, the first bush section 25 forms a first radial bearing surface 27 and the second bush section 26 forms a second radial bearing surface 28. A first axial bearing surface 31 is formed on a first axial end 29 of the first bush section 25 and a second axial bearing surface 32 is formed on a second axial end 30 of the second bush section 26. The first axial bearing surface 31 and the second axial bearing surface 32 tightly abut on the respective inner surfaces 22 and 23 of the mould. In this case, a distance between the inner surfaces 22 and 23 of the mould essentially corresponds to a length L of the plain bearing bush 20.

[0040] The second bush section 26 forms a connecting section 33 with an inside diameter 34, which is larger than an inside diameter 35 of the radial bearing surfaces 27 and 28 such that a gap 36 is formed on the mandrel 34 in the connecting section 33. In addition, a connecting fit 37 is produced between the first bush section 25 and the second bush section 26 with an inside diameter 38 on the second bush section 26 and an outside diameter 39 on the first bush section 25. The connecting fit 37 allows a relative motion between the bush sections 25 and 26, wherein the connecting fit 37 prevents polymeric material from passing into the gap 36 during its injection into the mould 21.

[0041] A radial gap 40, into which the polymeric material penetrates during the transfer moulding or injection moulding process, furthermore is formed between the first bush section 25 and the second bush section 26 in the region of the connecting fit 37. As a result, the first bush section 25 and the second bush section 26 are respectively pressed in the direction of the arrows 41 and 42 such that the first axial bearing surface 31 and the second axial bearing surface 32 are pressed against the respective inner surfaces 22 and 23 of the mould. In this case, mechanical processing of the plain bearing bush 20 is no longer required after the polymeric material of the rotor has cured. A potential shrinkage can be ignored during the production of the bush sections 25 and 26 because the already finished bush sections 25 and 26 are adapted to the length L of the plain bearing bush 20 in the mould 21. Nevertheless, it is possible to choose different materials for the bush sections 25 and 26 in order to adapt the bush sections 25 and 26 even better to a potential load. In the plain bearing bush 20, the first bush section 25 is arranged in the region of a not-shown impeller of the rotor.