EC motor with cast armature shaft

Abstract

An EC motor is provided having a stator, in which an armature is rotatably supported, the armature including an armature shaft, on which an armature core having a plurality of permanent magnets is held, the armature core being electrically insulated against the armature shaft with the aid of a casting compound, and a balance ring being provided on at least one axial end of the armature core, which is accommodated on the armature shaft by a central recess, a gap between the armature shaft and the central recess of the balance ring being filled with casting compound, and the permanent magnets being held in pockets of the armature core by casting compound.

Claims

1. An EC motor comprising: a stator in which an armature is rotatably supported, the armature including an armature shaft on which an armature core having a plurality of permanent magnets is held, the armature core being electrically insulated against the armature shaft via a casting compound; a balance ring provided on at least one axial end of the armature core, which is accommodated on the armature shaft by a central recess, wherein the central recess of the balance ring forms a gap between the armature shaft and the balance ring, the gap being filled with the casting compound, wherein the permanent magnets are held in pockets of the armature core by the casting compound, and wherein the gap formed by the central recess of the balance ring is designed as a sprue for introducing the casting compound into a further gap, provided between the armature core and the armature shaft, as well as into the pockets of the armature core.

2. The EC motor according to claim 1, wherein the balance ring is provided on both ends of the armature core, such that two balance rings are provided which each have the gap designed as the sprue for introducing the casting compound into the further gap, provided between the armature core and the armature shaft as well as into the pockets of the armature core.

3. The EC motor according to claim 1, wherein an outer diameter of the balance ring corresponds to an outer diameter of the armature core.

4. The EC motor according to claim 1, wherein the balance ring is closed in a direction of the armature core by an annular projection on a side facing the armature core.

5. The EC motor according to claim 4, wherein the annular projection is flush with an outer surface of the balance ring.

6. The EC motor according to claim 4, wherein the annular projection axially supports the permanent magnets.

7. The EC motor according to claim 4, wherein the balance ring has an inner circumferential surface facing the armature shaft and an outer circumferential surface facing away from the armature shaft, wherein the annular projection projects toward the side of the balance ring facing the armature core at a position that is closer to the outer circumferential surface than the inner circumferential surface.

8. The EC motor according to claim 1, wherein the central recess of the balance ring is provided with form-fitting elements in the form of seams or grooves.

9. The EC motor according to claim 1, wherein the balance ring is made from a brass alloy or a comparable non-magnetic material, and wherein the armature shaft is made from steel.

10. The EC motor according claim 1, wherein, with respect to an axial direction of the armature shaft, a portion of the balance ring is spaced apart from the armature core and the pockets so as to form a spacing that is in fluid communication with the gap formed by the central recess of the balance ring to introduce the casting compound in the gap formed by the central recess of the balance ring into the pockets.

11. An EC motor comprising: a stator in which an armature is rotatably supported, the armature including an armature shaft on which an armature core having a plurality of permanent magnets is held, the armature core being electrically insulated against the armature shaft via a casting compound; a balance ring provided on at least one axial end of the armature core, which is accommodated on the armature shaft by a central recess, wherein the central recess of the balance ring forms a gap between the armature shaft and the balance ring, the gap being filled with the casting compound, wherein the permanent magnets are held in pockets of the armature core by the casting compound, and wherein at least one of the permanent magnets is fixed in a respective one of the pockets by a protruding nose of a lamination of the armature core, and wherein at least two or four laminations have the nose.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 shows a greatly simplified representation of an EC motor according to the invention;

(3) FIG. 2 shows an enlarged longitudinal sectional view of the armature shaft of the EC motor according to FIG. 1;

(4) FIG. 3 shows an enlarged section of detail III according to FIG. 2;

(5) FIG. 4 shows an enlarged section of detail IV according to FIG. 2;

(6) FIG. 5 shows a cross sectional view of the armature along line V-V according to FIG. 2; and

(7) FIG. 6 shows a top view of one mold half of a casting mold, in which the armature, including its motor shaft, the armature core and the two balance rings, is inserted prior to supplying the casting compound, the motor shaft, the armature core and the balance rings being illustrated in a cutaway view.

DETAILED DESCRIPTION

(8) FIG. 1 shows a simplified representation of an EC motor according to the invention.

(9) Motor 10 comprises a stator 12, which has a plurality of stator windings. An armature 16 is rotatably supported within stator 12, which has a plurality of permanent magnets 18. Stator 12 is activated with the aid of an activator 14 having a rotating field, by means of which the rotation of armature 16 is generated.

(10) FIG. 2 shows an enlarged longitudinal sectional view of an armature 16 according to the invention according to FIG. 1.

(11) Armature 16 includes a motor shaft 20, which is lathed from tool steel. An armature core 22 is accommodated on armature shaft 20, in which four permanent magnets 18 are accommodated, tangentially to each other, at uniform angular distances from each other. Permanent magnets 18 are held in pockets 36 of armature core 22 and fixed with the aid of casting compound 28.

(12) A balance ring 24, 26, which is made from brass or a comparable non-magnetic material, is provided on each of the two axial ends of armature core 22. Gaps 32, 34, which are filled with casting compound 28, are provided between balance rings 24, 26 and the outer surface of the motor shaft. Casting compound 28 also extends continuously into a gap 30 between armature core 22 and the outer surface of motor shaft 20 as well as into pockets 36, in which permanent magnets 18 are accommodated. Gap 32, 34 between balance rings 24, 26 are used to supply casting compound 28 to gap 30 between armature core 22 and armature shaft 20 as well as to pockets 36, in which permanent magnets 18 are accommodated, during an injection molding operation.

(13) Balance rings 24, 26 are provided for balancing armature 16 later on after the casting of armature 16. As is apparent in greater detail from FIGS. 3 and 4, balance rings 24, 26 are provided with form-fitting elements 33, 35 at their central recesses, which are designed as seams, so that a form-fitting connection with casting compound 28 results after the casting compound is cured.

(14) An annular projection 38, 39 is formed on each balance ring 24, 26 in the direction of armature core 22. The outer surface of balance rings 24, 26 and of annular projection 38, 39 is designed to be flush with the outer surface of armature core 22. Annular projections 38, 39 are used to seal balance rings 24, 26 against armature core 22 during the injection molding operation.

(15) To facilitate a fixing of permanent magnets 18 within pockets 36 prior to the injection molding operation, multiple laminations 40, 44 are formed on armature core 22, each having a nose 42 and 46, respectively, which project into pockets 36. Permanent magnets 18 may be fixed in pockets 36 by noses 42, 44 prior to the injection molding operation.

(16) FIG. 6 shows a sectional view of an injection mold 50, 51, into which armature shaft 20 is introduced, together with armature core 22 and the two balance rings 24, 26. Motor shaft 20, balance rings 24, 26 and armature core 22 are centered with respect to each other in mold 50, 51 by correspondingly shaped recesses. The second mold half 51 is pressed on prior to the injection molding operation, and casting compound is supplied via one or multiple sprues 52 through mold 51 into the cavity, which is formed between mold 50, 51, the outer surface of motor shaft 20, balance rings 24, 26 and armature core 22.

(17) Casting compound 28 is distributed under pressure into the corresponding cavities, so that a cast armature 16 according to FIG. 2 results after casting compound 28 is cured.

(18) FIG. 5 shows a cross sectional view of armature 16 along line V-V according to FIG. 2.

(19) It is apparent that both armature core 22 and armature shaft 20 are provided with assigned form-fitting elements to ensure a form-fitting connection and thus a secure transmission of torque after casting compound 28 is cured.

(20) Permanent magnets 18 are secured against an axial displacement during the injection molding operation by a stop against annular projection 38 of balance ring 26. The stop against annular projection 38 takes place in the edge area (cf. FIG. 5) of permanent magnets 18.

(21) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.