EP3232450A1

EP3232450A1 - Magnetic fluid and particular geometry for parts of electromagnetic apparatus

Info

Publication number: EP3232450A1
Application number: EP16020132.3A
Authority: EP
Inventors: Harri VIHRIÄLÄ
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-04-13
Filing date: 2016-04-13
Publication date: 2017-10-18

Abstract

An electromagnetic apparatus, including at least two discrete parts (1) before assembly/operation. During assembly, operation, these parts are pressed against each other, whereby the flexible joints (2) deform due to place given by the cavity (3). These joints do not have any locking function. The cavities can have a geometry of a groove (2) or a hole (5) completely surrounded by a ferromagnetic piece). In addition, a ferromagnetic fluid (6) can be inserted between the parts to enhance the magnetic permeability.

Description

R. 42(1)(a) Technical field to which invention relates

The present invention relates to an electromechanical apparatus and, more particularly, to an electromechanical apparatus consisting two or more discrete ferromagnetic parts before assembly.

R. 42(1)(b) Indication of the background art

In a conventional electromagnetic apparatus, a ferromagnetic material forms a path for a magnetic flux to flow. In several cases, this material has discontinuities, i.e. it is broken up to two or more discrete parts. During assembly and /or operation of the apparatus, these discrete parts are brought together. However, due to manufacturing tolerances, required slack for assembly or for other reasons, there remain gaps between these ferromagnetic parts, which requires more magnetization power and increases losses or permanent magnets material, since permeability of the air is a magnitude of thousand smaller than that of ferromagnetic material, like iron. Moreover, due to varying magnetic forces during the operation these parts may begin to colliding each other causing noise and a risk of breaking down.

R. 42(1)(c) Technical problem to be solved

The objective of the present invention is to provide means to reduce this magnetic air gap between the ferromagnetic parts.

R 42(1)(c) Disclosure of invention

In accordance with the present invention, geometry is provided for the ferromagnetic parts in a way that the cavities and gaps between the parts are filled. In addition a ferromagnetic fluid is presented, which further fills these gaps and cavities. These both methods used individually or simultaneously in an electromagnetic apparatus will reduce the magnetization power
Electromagnetical apparatus has a path made for magnetic flux from ferromagnetic material. This material has a high permeability, i.e. it conducts the magnetic flux effectively. However, due to various reasons, like e.g. manufacturing, transportation and supplier structure, this path is broken into discrete pieces. These parts are then re-connected during assembly and/or operation of the apparatus. Due to manufacturing tolerances, spaces left for movement or for other reasons, there remain gaps between the discrete parts. These gaps require more magnetization power and/or more permanent magnet material to attain the same level of magnetic flux as without the gaps. These gaps may begin to move against each other, the collisions causing noise and risk of breakdown.
To eliminate and/or reduce the gaps, it is proposed to introduce a geometry, which is larger than nominal space reserved for this part and when touched by adjacent parts, deforms providing a flexible contact between the parts. Natural plasticity of the material will attain the contact also during environmental effects, like heat expansion, vibrations and mechanical forces.
The geometry provides a cavity inside the part itself, which provides a needed lower thickness between the outer edge of the part and cavity.
There may be variety of cavities and/or grooves with differentiating spaces, depths and wall thicknesses which able the varying of the stiffness of the flexibility.
Likewise, the protruding parts can also be used for interlocking of the parts as a side effect. This feature in itself is well known.
In addition to the geometry, a magnetic fluid can be used to further to increase the permeability. Magnetic fluid in itself is a known invention. Here the fluid containing ferromagnetic particles is inserted between the ferromagnetic pieces. The fluid can be made with higher viscosity in applications were may by dismounted later, i.e. a segment of electrical machine is to be replaced. This ensures that the fluid does not flow away from the gap but the parts can be still removed.
For apparatuses which must not be dismounted ever, one can use curing fluid like two-component epoxy. There are also variants which remain slightly plastic, allowing 1-2% contraction/expansion in cured state.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

R. 42(1)(d) Brief description of drawings

In the drawings:

Fig. 1 shows ferromagnetic parts as individual segments (1) with protruding parts (2) formed, which have groove (3).
In Fig. 2 the segments (1) are assembled together, and the
Fig. 3 shows an enlarged view of assembled state: The protruding parts (2) contact each other at point (4) and have deformed.
In Fig. 4 an alternative geometry of cavity is shown, a hole (5), which also deforms when in contact which adjacent part (1). The Fig. 4 the ferromagnetic fluid (6) is also inserted into the gap between the parts to enhance the permeability of the gap.

R. 42(1)(e) Description of at least one way of carrying out the invention

The invention can be used in the electromacnetic machines, which is made of segments (1). To the rotor segments can be designed in a manner that when the rotor segments are tightened, the protruding parts (2) touch the adjacent segments, deforming and keeping the gap in minimum. In addition, the ferromagnetic fluid can be made by inserting ferromagnetic particles into both components of epoxy. When mixed and inserted between the segments (1; before assembly) it cures and creates a conductive bridge between the segments.

Claims

An electromagnetic apparatus and manufacturing method of it, compromising at least two discrete ferromagnetic parts (1) before assembly and/or operation where at least one adjacent edge of at least one ferromagnetic part is designed in a fashion, that at least one part (2) exceeds the geometric middlepoint (4) of the intersection between the parts when unassembled. When pressed together these protruding edges (2) contact the adjacent parts at least in one point of touch during the time the parts are together.
The apparatus in accordance to the claim 1, where the design contains at least one cavity (5) and/or groove (3) in order to attain at required flexibility.
Magnetic fluid (6) which has a considerably higher permeability than air is inserted into the apparatus described in the claim one that may or may not have the protruding parts (2).
The magnetic fluid (6) in accordance to claim 3 may be curing and it may be used to attach the parts (1) together.