Electro-magnetic bearing assembly with inner ventilation to cool the bearing

Abstract

A magnetic bearing assembly for a rotary machine, having a rotor circuit and a stator magnetic circuit secured to a stationary support element having at least one body of ferromagnetic material and at least one coil, both being fitted in a protective annular housing leaving uncovered a surface of revolution of said ferromagnetic body and a surface of revolution of said one coil facing a surface of revolution of the rotor circuit. The bearing assembly comprises at least one row of blades secured on the rotor circuit.

Claims

1. A magnetic bearing assembly for a rotary machine comprising: a rotor circuit; a stator magnetic circuit secured to a stationary support element, and comprising two bodies of ferromagnetic material and at least one coil fitted in a protective annular housing leaving uncovered a surface of revolution of the two bodies of ferromagnetic material and a surface of revolution of the at least one coil facing a surface of revolution of the rotor circuit; and at least one row of blades secured on the rotor circuit, the rotor circuit comprises an annular thrust collar having an axial portion secured to a rotor shaft and radially extending towards the stator magnetic circuit by a radial portion, the radial portion facing the uncovered surfaces of the two bodies of ferromagnetic material and the at least one coil, each of the two bodies of ferromagnetic material face a radial lateral surface of the radial portion of the annular thrust collar, and each of the at least one row of blades is secured on the axial portion of the thrust collar and radially located between the annular thrust collar and the stator magnetic circuit.

2. The magnetic bearing assembly according to claim 1, wherein the at least one row of blades comprises a plurality of blades extending from the rotor circuit.

3. The magnetic bearing assembly according to claim 1, wherein the bearing is an axial magnetic bearing.

4. The magnetic bearing assembly according to claim 1, wherein the at least one row of blades comprises a plurality of axial blades.

5. The magnetic bearing assembly according to claim 1, wherein the at least one row of blades comprises a plurality of radial blades.

6. The magnetic bearing assembly according to claim 1, wherein the at least one row of blades comprises a plurality of blades which shape is a combination of the radial and axial type.

7. The magnetic bearing assembly according to claim 1, comprising two rows of blades.

8. A turbo machine comprising a stator, a rotor mounted in rotation in the stator, and at least one magnetic bearing assembly according to claim 1 radially arranged between the rotor and the stator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will be better understood from studying the detailed description of a number of embodiments considered by way of entirely non-limiting examples and illustrated by the attached drawings in which:

(2) FIG. 1 is an axial half-section of the magnetic bearing assembly according to a first embodiment of the invention;

(3) FIG. 2 is an axial half-section of the magnetic bearing assembly according to a second embodiment of the invention; and

(4) FIG. 3 is a cross-section according to the line III-III of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(5) The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale.

(6) As illustrated on FIG. 1, a magnetic bearing assembly, designed by general reference number 10, is designed to be mounted in a rotary machine (not shown) comprising a casing or housing, a rotating shaft 12 extending along an axis X-X and adapted to support a rotor part (not shown). For example, if the rotating machine is a centrifugal compressor, the rotor part comprises impellers.

(7) As illustrated on FIG. 1, the magnetic bearing 10 is of the axial type and is designed to support the rotor shaft 12 inside the stator casing.

(8) The active magnetic bearing 10 comprises a stator armature 14 fixed to the stator casing and a rotor armature 16 or annular thrust collar having the shape of a disk secured to the rotating shaft 12.

(9) The annular thrust collar 16 and the rotor shaft 12 form the rotor circuit 17. The annular thrust collar 16 extend s radially from an axial plate 16a secured to the rotor shaft 12 towards the stator magnetic circuit 18 by a radial portion 16b having an outer cylindrical surface 16c and two lateral surfaces 16d, 16e.

(10) The stator armature 14 comprises a stator magnetic circuit 18 including, in conventional manner, one or more annular coils 20 and two ferromagnetic bodies 22 which may be massive or laminated locally. In the example of FIG. 1, each ferromagnetic body 22 encloses two annular coils 20. The stator armature 14 also comprises a protective annular support or annular housing 24 into which is placed the stator magnetic circuit 18, leaving uncovered a surface of revolution 22a of the ferromagnetic bodies 22 and a surface 20a of revolution of each coils 20. The support 24 is secured to a stationary support element 26 that is itself fixed to the casing. As illustrated, the surfaces of revolution 20a, 22a are the axial lateral surface.

(11) As illustrated, the radial portion 16b of the thrust collar 16 faces the uncovered surfaces 20a, 22a respectively of each ferromagnetic bodies 22 and each coils 20. In other words, the stator magnetic circuit 18 is placed axially facing one of the radial lateral surface 16d, 16e of the radial portion 16b of the annular thrust collar 16 with no mechanical contact, leaving an axial gap 28 between the annular thrust collar 16 and the stator magnetic circuit 18.

(12) The rotation shaft 12 may be provided with a stepped profile 12a for an axial positioning of the thrust collar 16. Alternatively, the annular thrust collar 16 could, for example, be made integrally with the rotor shaft 12.

(13) As illustrated on FIG. 1, the bearing assembly 10 comprises two rows of blades 30, 32 comprising a plurality of blades (not shown) which can be axial or radial or a combination thereof, secured on the axial plate 16a of the thrust collar 16. The blade s 30, 32 extend radially from the annular thrust collar 16 towards the stator magnetic circuit 18. Alternatively, the rows of blades 30, 32 can be secured directly to the rotor shaft 12. As illustrated, each row of blades 30, 32 can be radially located between the annular thrust collar 16 and each annular housing 24 of the stator magnetic circuits 18, leaving a radial air gap 34 between the annular housing 24 and one of the rows of blades 30, 32.

(14) Such row s of blades 30, 32 increase the ventilation inside the magnetic bearing and allow the magnetic bearing to be cooled.

(15) The embodiment shown in FIGS. 2 and 3, in which identical parts bear the same reference, differs from the embodiment of FIG. 1 in the type of magnetic bearing.

(16) As illustrated on FIGS. 2 and 3, the magnetic bearing 40 is of the radial type and is designed to support radially the rotor shaft 12 inside the stator casing.

(17) The radial magnetic bearing 40 comprises a stator armature 42 fixed to the stator casing and the rotating shaft 12 forming the rotor circuit 17. Alternatively, an additional rotor armature may be secured to rotor shaft 12 facing the stator armature 42.

(18) The stator armature 42 comprises a stator magnetic circuit 44 including, in conventional manner, one or more coils 46 and one annular ferromagnetic body 48 which may be massive or laminated locally. As shown in FIG. 3, the ferromagnetic body 48 encloses four circumferentially equally spaced coils 46. The stator armature 42 also comprises a protective annular support or annular housing 50 into which is placed the stator magnetic circuit 44, leaving uncovered a surface of revolution 48 of the ferromagnetic body 48 and a surface 46a of revolution of each coils 46. The protective annular support 50 is secured to a stationary support element 52 that is itself fixed to the casing.

(19) As illustrated, the outer cylindrical surface 12b of the rotor shaft 12 faces the uncovered surfaces 46a, 48a respectively of ferromagnetic body 48 and each coils 46, In other words, the stator magnetic circuit 44 is placed radially facing the outer cylindrical surface 12b of the rotor shaft 12, leaving a radial gap 54 between the rotor shaft 12 and the stator magnetic circuit 44.

(20) As illustrated on FIG. 2, the bearing assembly 40 comprises two rows of blades 56, 58 comprising a plurality of blades (not shown) which can be axial or radial or a combination thereof, secured on the outer cylindrical surface 12b of the rotor shaft 12. The blades 56, 58 extend axially from the rotor shaft 12 towards the stator magnetic circuit 44. As illustrated, the stator magnetic circuit 44 is located axially between the two rows of blades 56, 58, leaving an axial air gap 59 between the annular housing 50 and each of the rows of blades 56, 58.

(21) As an example, a magnetic bearing assembly may comprise the combination of a radial type magnetic bearing 40 as shown on FIG. 2 associated to the axial type magnetic bearing 10 as shown on FIG. 1 to support the rotating shaft 12.

(22) The each magnetic bearing assembly has enhanced cooling flow.

(23) Indeed, the rows of blades facilitate the pumping of the flow of fluid enhancing the cooling of the active magnetic bearing. The magnetic bearing is thus provided with inner ventilation.

(24) This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.