WO2021198800A1

WO2021198800A1 - An apparatus for mounting a permanent magnet and a method thereof

Info

Publication number: WO2021198800A1
Application number: PCT/IB2021/050989
Authority: WO
Inventors: Gomathi Venkatraju
Original assignee: Gomathi Venkatraju
Priority date: 2020-04-03
Filing date: 2021-02-08
Publication date: 2021-10-07

Abstract

An apparatus for mounting a permanent magnet is provided. The apparatus includes a glue tank mechanically coupled to a surface of a rotor rim, wherein the glue tank is configured to store a pre-defined amount of glue, wherein an inner surface of the glue tank comprises one or more pre-guiding dovetail keys, wherein a predefined amount of glue is applied to the one or more pre-guiding dovetail keys, the permanent magnet, and the one or more pre-guiding dovetail key ways. A pushing mechanism mechanically coupled to a top surface of the glue tank, wherein the pushing mechanism comprises an actuating device to actuate and align the one or more dovetail key in the permanent magnet over the one or more pre-guiding dovetail keyways, thereby preventing the permanent magnet from movement between the one or more pre-guiding dovetail keys and the one or more dovetail key ways.

Description

AN APPARATUS FOR MOUNTING A PERMANENT MAGNET AND A

METHOD THEREOF

This International Application claims priority from a Patent application filed in India having Patent Application No. 202041014861, filed on April 03, 2020, and titled “AN APPARATUS FOR MOUNTING A PERMANENT MAGNET AND A METHOD THEREOF”.

FIELD OF THE INVENTION

Embodiments of the present disclosure relate to mounting permanent magnets, and more particularly to, an apparatus for mounting permanent magnets that form magnetic poles on a permanent magnet support surface of the rotor of an electric machine.

BACKGROUND

Permanent magnets are often used in large electrical machines such as motors or generators. Such an electrical machine comprises two basic components, namely a field for creating magnetic flux, and an armature for generating electromotive force and for carrying current crossing the field. The armature usually comprises conductive coils wrapped on a stator, while the field usually comprises magnets arranged on a rotor. The rotor can surround the stator or vice versa, and the magnets and coils face each other across a narrow air gap. The established methods of loading or mounting permanent magnets onto the field of an electrical machine comprise various steps such as enclosing the individual permanent magnet poles in housings and gluing the permanent magnet poles to the field (usually the rotor), wrapping the entire arrangement in fibreglass bandage or enclosing it in a vacuum bag, pumping resin into the bag and performing vacuum extraction to consolidate the permanent magnet poles to the rotor body. These methods are accompanied by various problems such as the extensive and therefore costly effort involved in securing the permanent magnets to the field. Therefore, in order to overcome the abovementioned problem, there exists a need for an improved apparatus and method to fix the permanent magnet on the rotor inner circumference.

BRIEF DESCRIPTION

In accordance with one embodiment of the disclosure, an apparatus for mounting a permanent magnet is provided. The apparatus includes a glue tank mechanically coupled to a surface of a rotor rim, wherein the glue tank is configured to store a pre defined amount of glue, wherein an inner surface of the glue tank comprises one or more pre-guiding dovetail keys, wherein a predefined amount of glue is applied to the one or more pre-guiding dovetail keys, the permanent magnet, and the one or more pre-guiding dovetail key ways. The apparatus also includes a pushing mechanism mechanically coupled to a top surface of the glue tank, wherein the pushing mechanism comprises an actuating device to actuate and align the one or more dovetail key in the permanent magnet over the one or more pre-guiding dovetail keyways, thereby preventing the permanent magnet from movement between the one or more pre-guiding dovetail keys and the one or more dovetail key ways.

In accordance with another embodiment of the disclosure, a method thereof is provided. The method includes applying a predefined amount of glue on the permanent magnet and one or more pre-guiding dovetail keys; aligning the permanent magnet to the one or more pre-guiding dovetail keys; and actuating, by a pushing mechanism, the one or more dovetail key ways in the permanent magnet over the one or more pre- guiding dovetail key, thereby preventing the permanent magnet from movement between the one or more pre-guiding dovetail keys and the one or more dovetail key ways.

To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures. BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:

FIG. 1 illustrates a pictorial depiction of an apparatus for mounting a permanent magnet in accordance with an embodiment of the present disclosure;

FIG. 2 illustrates a pictorial depiction of a pushing mechanism of FIG. 1 , in accordance with an embodiment of the present disclosure;

FIG. 3 illustrates a pictorial depiction of segmental permanent magnets with glue formed the magnetic poles in rotor rim of FIG. 1, in accordance with an embodiment of the present disclosure;

FIG. 4 illustrates pictorial depiction ross- sectional view of rotor rim of with permanent magnetic poles made out of using glue and the segments of the permanent magnets, in accordance with an embodiment of the present disclosure;

FIG. 5 illustrates pictorial depiction of alternate poles in accordance with an embodiment of the present disclosure;

FIG. 6 illustrates a cross-sectional view of rotor rim with permanent magnetic poles made out of using glue and the segments of the permanent magnets, in accordance with an embodiment of the present disclosure; and

FIG. 7 illustrates a flow chart representing steps involved in a method of FIG. 1 in accordance with an embodiment of the present disclosure.

Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein. DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.

In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

FIG. 1 illustrates a pictorial depiction of an apparatus (100) for mounting a permanent magnet in accordance with an embodiment of the present disclosure. The apparatus (100) includes a rotor, wherein a rotor rim (102) is mechanically coupled to a mounting surface (110). The mounting surface (110) is mechanically coupled to multiple female pre-guiding dovetail keys (104). In one embodiment, the multiple female pre-guiding dovetail keys (104) are mechanically coupled to the mounting surface (110) via multiple fasteners (108) such as including, but not limited to, screws. Multiple pole separators (106) are mechanically coupled to the mounting surface (110), wherein the multiple pole separators (106) are placed in between a predefined number of multiple female pre-guiding dovetail keys (104). In one embodiment, a pole separator (106), from the multiple pole separators (106) is positioned in between a set of four female pre-guiding dovetail keys (104). The multiple female pre-guiding dovetail keys (104) are fixed as per design in rotor rim (102) at a predetermined tangential distance from each other. The pole separator (106) will be grooved and fixed in between the adjacent poles at the rotor rim (102) pole surface (110). Multiple male pre-guiding dovetail keys (114) are mechanically coupled to the multiple female pre-guiding dovetail keys (104). In one embodiment, a set of four male pre-guiding dovetail keys (114) are mounted on the set of four female pre-guiding dovetail keys (104). A glue tank (112) is mechanically coupled to the rotor rim (102). In one embodiment, the glue tank (112) is mechanically coupled to the rotor rim (102) via multiple clamping screws (118). The glue tank (112) stores a predefined amount of glue, wherein the inner surface of the glue tank (112)is mechanically coupled to the multiple male pre-guiding dovetail keys (114), wherein a predefined amount of glue is applied to the multiple male pre- guiding dovetail keys (114).

FIG. 2 illustrates a pictorial depiction (200) of a pushing mechanism (202) of FIG. 1, in accordance with an embodiment of the present disclosure. In addition to the aforementioned description of the apparatus in FIG. 1, the pushing mechanism (202) is mechanically coupled to a top surface of the glue tank (112). In one embodiment, the pushing mechanism (202) is mechanically coupled to the rotor rim (102) via multiple pillars (208). In one embodiment, a permanent magnet (210) is placed at a pre-defined distance from the multiple male pre-guiding dovetails keys (114). In one embodiment, four permanent magnets (210) are placed at the predefined distance from the set of four multiple male pre-guiding dovetail keys (114). In one embodiment the permanent magnet (210) is designed to have a dovetail groove. A magnetic steel sheet (116) is placed on top of the multiple male pre-guiding dovetail keys (114) and the multiple female pre-guiding dovetail keys (104). The multiple female pre-guiding dovetail keys (104) are fixed on the glue tank (112) top over and above the magnetic steel sheet (116) which is placed at the top of the rotor rim (102). The glue tank (112) seating surface at a pole surface of rotor rim (102) with O’ ring grooves are provided to arrest the glue (212) leakage during the process for permanently mounting the permanent magnet (210). In one embodiment, the pushing mechanism (202) is a hydraulic pushing mechanism. In one embodiment, the pushing mechanism (202) includes an actuating device (204). In one embodiment, the pushing mechanism (202) is non-magnetic. In one embodiment, the actuating device (204) is a hydraulic piston. The actuating device (204) is mechanically coupled to multiple pre-guiding dovetail keyways (206). In one embodiment, the permanent magnets (210) with dovetail grooves are applied with the predefined amount of glue, similar to the predefined amount of glue applied to the multiple male pre-guiding dovetail keys (114). The multiple pre-guiding dovetail keyways (206) are aligned in associated with the multiple male pre-guiding dovetails keys (114), wherein the actuating device (204)is actuated to pass the multiple pre-guided dovetail keyways (206) into the multiple male pre-guiding dovetail keys (114) through the dovetail groove of the permanent magnets (210). Once the permanent magnet (210) is locked between the multiple pre-guiding dovetail keys (206) and the multiple male pre-guiding dovetail keyways (114), the predefined amount of glue applied is cured, thereby preventing the permanent magnet (210) from movement between the multiple male pre-guiding dovetail keys (114) and the multiple pre-guiding dovetail keyways (206).

FIG. 3 illustrates a pictorial depiction of segmental permanent magnets (300) with glue formed the magnetic poles (304) in rotor rim (102) of FIG. 1, in accordance with an embodiment of the present disclosure. In addition to the aforementioned description of the apparatus (100) in FIG. 1, in one embodiment, a predefined amount of glue (212)is filled up to a predefined height over and above the multiple female pre-guiding dovetail keys (104), thereby enabling easy travel of the permanent magnets (210) without friction into the multiple female pre-guiding dovetail keys(104) in a predefined position and rest with the help of a bottom locker (306). The segmented permanent magnets (300) form an alternative magnetic north and south poles (304) in the rotor rim (102)of asynchronous machine for fixing the permanent magnets (210) in the rotor rim (102) at the pole surface (110) in the multiple female pre-guiding dovetail keys (104), wherein the multiple female pre-guiding dovetail keys (104)are rigidly fixed in the pole surface (110) of the rotor rim (102) with screwing at four locations of each of the multiple female pre-guiding dovetail keys (104). Turning to FIG. 4 and FIG. 5, the FIG. 4 illustrates pictorial depiction cross-sectional view (400) of rotor rim (102) with permanent magnetic poles (304) made out of using glue (212) and the segments of the permanent magnets (300), in accordance with an embodiment of the present disclosure. FIG. 5 illustrates pictorial depiction of alternative poles (500) of multiple female pre-guiding dovetail keys in accordance with an embodiment of the present disclosure. The multiple female pre-guiding dovetail keys (104) are fixed as per design in the rotor rim (102) at a predetermined tangential distance from each other. The pole separators (106) will be grooved and fixed in between the adjacent poles at the rotor rim (102) pole surface (110). The multiple male pre-guiding keys (114) are fixed rigidly in the rotor rim (102) at the permanent magnet pole area with the multiple fasteners (108) at the predefined locations on the entire circumference of the rotor with suitable offset. In one embodiment, each pole has 4 male pre-guiding dovetail keys (114). Therefore, 4 x 88 = 352 male pre-guiding dovetail keys are fixed perpendicularly to the rotor rim (102). In each of the 4 male pre-guiding dovetail keys (114), 13 permanent magnets (210) are driven and fixed at the pre-defined position as per the design. Therefore, in total, 52 segments of the permanent magnets (210) create a permanent magnetic pole in the synchronous machine. The alternative poles (500) are created in synchronous machine rotor with 2 types of permanent magnets - Type-1 creates North Pole (304) and Type- 2 creates South Pole (304). In one embodiment, the alternative poles (500) are created in synchronous machine rotor with 2 types of permanent magnets - Type-1 creates North Pole (304) and Type-2 creates South Pole (304). Therefore, the permanent magnets are made such a way with female dovetail key way at decided position of the permanent magnet. The permanent magnets are in solid rectangular type. After completing 13 strokes per pole, then the permanent magnets (210) are locked with a top locker (302). Once 13 strokes are completed, the total glue in the glue tank (112) will be drained at bottom. In one embodiment, about 30 to 40 microns thickness of glue coated all over surface of the permanent magnets (210) and filling the gaps in between the permanent magnets (210) and the rotor rim (102) to the permanent magnets (210); also the cured glue will arrest the vibrations in the permanent magnets (210). Therefore, the glue viscosity will be selected in such a way to achieve such results. The glue used for this process will be air dried at decided time duration, wherein the glue coating will act as an anti-corrosive layer and protect the permanent magnets (210) from the corrosion. FIG. 6 illustrates a cross-sectional view (600) of the rotor rim (102) with the permanent magnetic poles (304) made out of using glue (212) and the segments of the permanent magnets (300), in accordance with an embodiment of the present disclosure. In one embodiment, once multiple magnetic steel plates (602) are inserted up to the end of the permanent magnets (210), the magnetic steel parts (102, 116, and 602) give magnetic circuit push and pull action and help the permanent magnets (210)to travel to its targeted location smoothly without friction. The permanent magnets (210) is pushed by the pushing mechanism (202) with a predefined amount of constant pressure. During the process of permanently mounting the permanent magnets (210), glue (212) is filled to the predefined level and excess glue will overflow through a drainer (504). After completing the process and before removing the glue tank (112), the glue (212) is drained at the bottom of the glue tank (112) completely through a drain valve (506).

FIG. 7 illustrates a flow chart representing steps involved in a method (700) of FIG. 1 in accordance with an embodiment of the present disclosure. The method (700) includes applying a predefined amount of glue on the permanent magnet and multiple pre-guiding dovetail keys, in step 702. In one embodiment, the predefined amount of glue is applied to the multiple male pre-guiding dovetail keys and the permanent magnets. In one embodiment, the permanent magnets are rectangular and each of the permanent magnets includes dovetail groove. In one embodiment, the permanent magnets are positioned at a predefined distance from the multiple male pre-guiding dovetail keys. The method (700) includes aligning the permanent magnet to the multiple pre-guiding dovetail keys, in step 704. The method (700) includes aligning the permanent magnet to the multiple male pre-guiding dovetail keys. The method (700) includes actuating the multiple dovetail keyways in the permanent magnet over the one or more pre-guiding dovetail keyways, in step 706. The method (700) includes actuating, by a pushing mechanism, the multiple dovetail keyways in the permanent magnet over the multiple male pre-guiding dovetail keys. The pushing mechanism is mechanically coupled to a top surface of the glue tank. In one embodiment, the pushing mechanism is mechanically coupled to the rotor rim via multiple pillars. In one embodiment, the pushing mechanism is a hydraulic pushing mechanism. In one embodiment, the pushing mechanism includes an actuating device. In one embodiment, the pushing mechanism is non-magnetic. In one embodiment, the actuating device is a hydraulic piston. The actuating device is mechanically coupled to multiple pre-guiding dovetail key ways. The multiple pre-guiding dovetail key ways are aligned in associated with the multiple male pre-guiding dovetails keys, wherein when the actuating device is actuated to pass the multiple pre-guided dovetail keyways into the multiple male pre-guiding dovetail keys through the dovetail groove of the permanent magnets. Once the permanent magnet is locked between the multiple pre- guiding dovetail keys and the multiple male pre-guiding dovetail keyways, the predefined glue is cured, thereby preventing the permanent magnet from movement between the multiple male pre-guiding dovetail keys and the multiple pre-guiding dovetail keyways

The disclosed apparatus provides various advantages, including but not limited to, permanently mounting magnets into synchronous machines using glue and draining the overflow glue through the drainers.

While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependant on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.

Claims

I/WE CLAIM:

1. An apparatus (100) for mounting a permanent magnet, comprising: a glue tank (112) mechanically coupled to a surface of a rotor rim (102), wherein the glue tank (112) is configured to store a pre-defined amount of glue, wherein an inner surface of the glue tank (112)comprises one or more male pre guiding dovetail keys (114), wherein a predefined amount of glue is applied to the one or more male pre-guiding dovetail keys (114), the permanent magnet (210) and one or more pre-guiding dovetail keyways(206); and a pushing mechanism (202) mechanically coupled to a top surface of the glue tank (112), wherein the pushing mechanism (202) comprises an actuating device (204) to actuate and align the one or more male pre-guiding dovetail keys (114) in the permanent magnet (210) over the one or more pre-guiding dovetail key ways (206), thereby preventing the permanent magnet (210) from movement between the one or more male pre-guiding dovetail keys (114) and the one or more dovetail key ways (206).

2. The apparatus (100) as claimed in claim 1, wherein the glue tank (112) is fabricated of non-magnetic steel material and magnetic steel material.

3. The apparatus (100) as claimed in claim 2, wherein the non-magnetic steel material is used in the glue tank (112) at a permanent magnet pole area of the rotor.

4. The apparatus (100) as claimed in claim 1, wherein the pushing mechanism (202) comprises a hydraulic pushing mechanism.

5. The apparatus (100) as claimed in claim 1, wherein each of the one or more male pre-guiding dovetail keys (114) are placed at a predefined tangential distance from the one or more pre-guiding dovetail key ways (206).

6. The apparatus (100) as claimed in claim 1, wherein the permanent magnet (210) comprises a dovetail groove.

7. The apparatus (100) as claimed in claim 1, comprising multiple magnetic steel plates (502) mechanically coupled to a front and a backside of the one or more male pre-guiding dovetail keys (114) respectively.

8. The apparatus (100) as claimed in claim 1, wherein the multiple magnetic steel plates (502) aid in maintaining the permanent magnet (210) from movement upon gluing the permanent magnet (210) with the one or more pre-guided dovetail key ways (206) and the one or more male pre-guiding dovetail keys (114).

9. A method (700) for mounting a permanent magnet on a rotor comprising: applying (702) a predefined amount of glue on the permanent magnet and one or more pre-guiding dovetail keys; aligning (704) the permanent magnet to the one or more pre-guiding dovetail keys; and actuating (706), by a pushing mechanism, the one or more pre-guiding dovetail keyways in the permanent magnet over the one or more male pre-guiding dovetail key, thereby preventing the permanent magnet from movement between the one or more pre-guiding dovetail keys and the one or more pre-guiding dovetail keyways.

10. The method (700) as claimed in claim 9, comprising maintaining, by multiple magnetic steel plates, the permanent magnet from movement between the one or more pre-guided dovetail keyways and the one or more male pre-guiding dovetail keys.