SYSTEM FOR GROUNDING BEARINGS OF ROTARY ELECTRIC MACHINES, AND CORRESPONDING ELECTRIC MACHINE

Abstract

The present invention relates to a system for grounding bearings of rotary electric machines (200), especially rotary electric machines (200) controlled by frequency converters, the system comprising an outer ring (1), a contact ring (2), a support ring (3), elements (4) for fastening the rings, optional closure elements (5), elements (6) for fastening the assembly, elements (7) for adjusting the brush, a brush (8) made of a conductive material and a compressive fastening element (9), wherein the outer ring (1) is provided with at least two, preferably four to six housing holes (8A) for housing one or more grounding brushes (8). The present invention further relates to an electric machine provided with a system according to the invention.

Claims

1. A system for grounding bearings of rotary electric machines, especially rotary electric machines controlled by frequency converters, comprising: an outer ring, a contact ring, a support ring, elements for fastening the rings, optional closure elements, elements for fastening the assembly, elements for adjusting the brush, a brush made of a conductive material and a compressive fastening element, wherein the outer ring is provided with at least two, preferably four to six housing holes for housing one or more grounding brushes.

2. A system, according to claim 1, wherein in the internal diameter of the contact ring and the support ring chamfers are machined wherein the compressive fastening element is housed.

3. A system, according to claim 1 wherein the fastening of the assembly is made by the tightening of the elements for fastening the rings, whereby the rings are brought closer together and the decrease of the angle between the chamfers, forcing the compressive fastening element against the shaft of the rotary electric machine.

4. A system, according to claim 1, wherein the housing holes, not used, are closed by closure elements.

5. A system, according to claim 1, wherein the grounding brushes are conductive material rods, especially pure graphite or graphite with metal components and that they comprise a conductive spring fastened to its upper end, and an electrical contact point on the end of the conductive spring.

6. A system, according to claim 1, wherein the housing holes comprise part of its length threaded, and part of it smooth.

7. A system, according to claim 1, wherein in the apparent end of the elements for adjusting the brushes, there is a knurled handle.

8. A system, according to claim 1, wherein the outer ring can also comprise seals in the front part.

9. An electric machine comprising a system for grounding bearings of rotary electric machines, especially rotary electric machines controlled by frequency converters, comprising an outer ring, a contact ring, a support ring, elements for fastening the rings, optional closure elements, elements for fastening the assembly, elements for adjusting the brush, a brush made of a conductive material and a compressive fastening element, wherein the outer ring is provided with at least two, preferably four to six housing holes for housing one or more grounding brushes.

10. An electric machine, according to claim 9, wherein in the internal diameter of the contact ring and the support ring chamfers are machined wherein the compressive fastening element is housed.

11. An electric machine, according to claim 9, wherein the fastening of the assembly is made by the tightening of the elements for fastening the rings, whereby the rings are brought closer together and the decrease of the angle between the chamfers, forcing the compressive fastening element against the shaft of the rotary electric machine.

12. An electric machine, according to claim 9, wherein the housing holes, not used, are closed by closure elements.

13. An electric machine, according to claim 9, wherein the grounding brushes are conductive material rods, especially pure graphite or graphite with metal components and that they comprise a conductive spring fastened to its upper end, and an electrical contact point on the end of the conductive spring.

14. An electric machine, according to claim 9, wherein the housing holes comprise part of its length threaded, and part of it smooth.

15. An electric machine, according to claim 9, wherein in the apparent end of the elements for adjusting the brushes, there is a knurled handle.

16. An electric machine, according to claim 9, wherein the outer ring can also comprise seals in the front part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1: shows a perspective view of a system for grounding bearings of rotary electric machines according to the invention;

[0019] FIG. 2: shows a front view of a system for grounding bearings of rotary electric machines according to the invention;

[0020] FIG. 3: shows a side view of a system for grounding bearings of rotary electric machines according to the invention;

[0021] FIG. 4: shows a front view of a system for grounding bearings of rotary electric machines according to the invention;

[0022] FIG. 5: shows a side view of the A-A section of FIG. 4;

[0023] FIG. 6: shows a side view of the B-B section of FIG. 4;

[0024] FIG. 7: shows a front view of the assembly of the contact ring track;

[0025] FIG. 8: shows a side view of the A-A section of FIG. 7;

[0026] FIG. 9: shows a perspective view of a system for grounding bearings of a rotary electric machine comprising a system according to the invention;

DETAILED DESCRIPTION OF THE INVENTION

[0027] The mechanically protected grounding system according to the invention, or simply, the system (100), comprises an outer ring (1), a contact ring (2), a support ring (3), elements for fastening the rings (4) and, eventually, closure elements (5), elements for fastening the assembly (6), preferably screws, elements for adjusting the brush (7), conductive material brush (8) and compressive fastening element (9).

[0028] The outer ring (1) provides support and protection for the rest of the components by centralizing the assembly through an internal or external fitting located in the front cover of a rotary electric machine (200) comprising the shaft (210).

[0029] The outer ring (1) is made of a conductive material, preferably aluminum, comprising housing holes (8A) in which the grounding brushes (8) are housed, also fastening holes of a conductive material for housing the elements for fastening (6), and, finally, a space for housing the assembly of the contact ring (2) track. If requested, therein the installation of sealing systems is possible, making the system protected with a protection degree up to IP66.

[0030] In a preferred embodiment of the invention, the outer ring (1) is provided with at least two, preferably from four to six housing holes (8A).

[0031] The assembly of the contact track is formed by a contact ring (2), of a material with conductivity higher than that of steel, preferably copper, by which the contact with the grounding brushes (8) and their fastening elements occurs, which are: a support ring (3), compressive fastening element (9) and the elements for fastening the rings (4).

[0032] When the element for fastening the rings (4) from this assembly is tight, it promotes the approximation of the support ring (3) and the contact ring (2). In the internal diameter of these rings (2, 3), chamfers are machined, wherein the compressive fastening element (9) is housed. With the approach of the rings (2, 3), the angle between the chamfers closes, forcing the compressive fastening element (9) against the shaft (210) of the rotary electric machine (200). The pressure of this compressive fastening element (9) on the surface of the shaft (210) keeps the assembly fastened.

[0033] In a preferred embodiment of the invention, some of the housing holes (8A) may not be taken by the grounding brushes (8), the housing holes (8A) not being closed by closure elements (5). The closure elements (5) are, preferably, headless screws, which serve, therefore, to cover the housing holes (8A) that does not have grounding brushes (8) in its interior.

[0034] The grounding brushes (8) are, preferably, conductive material rods, especially graphite or pure graphite with metal components. They have a conductive spring (8B) fastened to its upper end, and a point of electrical contact on the end of the conductive spring (8B).

[0035] The fastening of grounding brushes (8) can be made in any of the housing holes (8A) present on the outer ring (1). The housing holes (8A) have a part of its length threaded, and the part smooth. The smooth part only houses the grounding brushes (8), keeping them radially positioned in relation to the shaft (210). In the threaded part of the housing holes (8A) the elements for adjusting the brush (7) are mounted, which limit the length of each of the housing holes (8A) in order to compress the conductive springs (8B) of the grounding brushes (8).

[0036] In the apparent end of the elements for adjusting the brushes (7), there is a knurled handle so that they can be mounted and removed without the use of tools providing access to the grounding brushes (8).

[0037] The system is provided for mounting a plurality of grounding brushes (8), in several positions and that can be disposed in symmetrical or non-symmetrical positions.

[0038] The purpose of the system (100) is to provide an alternative path to the bearing (not shown) to the effective drainage of the electric current.

[0039] This current passes from the shaft (210) of the rotary electric machine (200) to the contact ring (2) track mounted on the shaft (210) and then being transferred to the grounding brushes (8) in contact with it. The grounding brushes (8) are held in contact with the contact ring (2) track by means of conductive springs (8B), made of conductive material, with an electrical contact on its end. This contact transfers the current to the elements for adjusting the brushes (7) and to the outer ring (1) that supports the assembly. Therefrom, accordingly, the electric current may flow to grounding (not shown) through contact between the system (100) of the invention and the machined surface of the bearing cover of the rotary electric machine (200).

[0040] The conductive brushes (8) and the contact track of the contact ring (2) are strongly protected by the outer ring (1). This outer ring (1) can still be adapted to the installation of seals in its front part; the level of protection of the system can be raised up to the IP66 level.

CONCLUSION

[0041] It will be easily understood by those skilled in the art that changes can be made in the present invention without departing from the concepts exposed in the above description. These modifications must be regarded as included in the scope of the present invention. Consequently, the particular embodiments detailed above are only illustrative and exemplary and are non-restrictive as to the scope of the present invention, to which the full extent of the appended set of claims must be observed, and any and all correspondents thereof.