FI118839B - Locking the permanent magnets in an electric machine - Google Patents

Description

118839

LOCKING OF ELECTRICAL MACHINE PERMANENT MAGNETS

The invention relates to a stiffening device according to the preamble of claim 1 for locking permanent magnets in an electrical machine.

Recently, the use of permanent magnets in electrical machines, in particular synchronous machines, has become significantly more common. This is largely due to the development and affordability of the magnetic materials, as well as the simple construction and adjustment characteristics of the frequency converters to be connected to the synchronous machines. The permanent magnets are normally mounted on the rotor of the machine, either embedded in the ferromagnetic parts of the rotor or mounted on the rotor surface.

Adequate cooling of the rotor when using embedded magnets may require the formation of cooled air ducts in the rotor. Radial salt cooling is commonly known in electrical machine cooling technology, in which, for example, a cooling fan is passed through ferromagnetic portions of the rotor, through a pack of plates through radial passages to the periphery of the rotor and to the air gap of the machine. The radial cooling channels in the rotor extend in the radial direction of the machine from the shaft surface to the outer surface of the rotor to cool the entire iron portion of the rotor 15. The cooling air must therefore be provided with an unobstructed passage in the radial direction. . also for permanent magnets.

The permanent magnets used in the magnetization of an electrical machine are relatively small in relation to the length of the machine or the width of the hub of the machine, so that one permanent magnet pole is formed of several separate pieces. There may be several magnets, both wide and especially longitudinal • · φ * ··· * 20. In embedded permanent magnet solutions, permanent magnets may be introduced into the • · * · * · * rotor end into a channel formed for permanent magnets. On the one hand, permanent magnet pieces are made difficult by the fact that their magnetic forces are high when the permanent magnets are magnetized. On the other hand, permanent magnets and their coatings must not be damaged during installation, handling, or use of the electrical machine. Further, the permanent magnets must be locked in place to secure the radial cooling sol described above.

In the attachment of permanent magnets, it is known to fill the space between channels • and permanent magnet pieces formed by permanent magnets, for example with resin. In this procedure, it is not always possible, for example due to small clearances, to ensure that the resin is in the proper position to lock the permanent magnet. Locking magnets is particularly important before resin bonding, but during the operation of the electrical machine, the resin properties may be altered and its bonding ability reduced. Introducing the resin into often confined and difficult-to-reach areas makes it difficult to make the rotor.

The object of the invention is to provide a new, reliable and effective locking mechanism for permanent magnets of an electric rotor. To accomplish this, the invention is known from the features of the characterizing part of claim 15. Other preferred embodiments of the invention are characterized by the features of the dependent claims.

With the solution of the invention, the permanent magnet pieces are reliably held in place during the manufacture, transport and use of the electrical machine. For example, when inserting the rotor in an upright position during the resin process, the permanent magnet pieces 10 cannot move.

According to one embodiment of the invention, a groove is provided on the planar surface of the channel or permanent magnet for the permanent magnets or in which a mounting stick can be fitted. The clearance between the mounting stick and the permanent magnet block is such that the permanent magnet block is easily movable in the direction of the rotor axis.

According to a preferred embodiment, the clearance plates pass through a rotor shaft mounting strip or stick so that when the permanent magnet pieces are fitted, the coating of the permanent magnets is not damaged when the permanent magnets are slid over the permanent magnet piece. along the installation list or stick. Thus, the permanent magnet pieces do not touch the edges of the discs adjacent to the openings formed in the rotor disk pack.

• '*' 20 Sleeves or spacers that separate permanent magnets are easy to install during installation. They cannot move out of position after the mounting stick: is in place, so they cannot inadvertently interfere with the cooling air circulation in the radiator. Mounting sticks and play pieces made of non-magnetic material do not * significantly impair the electromagnetic properties of the electrical machine. Preferably mounting sticks. * · *. 25 is then made of fiberglass and the sleeves or spacers made of Teflon. Clearances may also be made of electrically conductive non-ferritic material such as aluminum or aluminum; of copper, which can at the same time act as part of the damping winding of the electrical machine.

• ·

According to a preferred embodiment of the invention, there are two or more mounting sticks in parallel so that they permanently support the permanent magnet pieces, especially during the installation step 30, when installing the permanent magnet pieces.

3 118839

In a preferred embodiment of the invention, a permanent magnet piece is attached to a permanent magnet piece adjacent to the rotor axis. In this case, it is not necessary to form the groove required by the mounting stick, and installing the play pieces does not involve any additional work steps. The groove or hole can also be made through the magnet using 5 mounting sticks. However, in these constructions, the cost of manufacturing the permanent magnets increases and the magnetization properties of the permanent magnets suffer.

The invention will now be described in detail with reference to some embodiments, with reference to the drawings, in which: - Figure 1 shows a partial perspective view of the rotor according to the invention; implementation; • ·;. * * * - FIG. 6 shows a fifth embodiment and. Figure 7 shows a sixth embodiment.

Figure 1 shows a partial, i.e. one fourth of the rotor in perspective view with the rotor intersecting the vertical axis and the horizontal axis. The figure shows an embodiment of the invention in the rotor 2 of a permanent magnet synchronous machine. The rotor comprises a rotor body 6 fitted to the shaft 4. formed of ferromagnetic plates The rotor body «« ·, ** ·, 20 has openings 8 through which cooling air flows into the rotor, for example, when forced by a shaft-mounted blower (not shown) The outer periphery of the rotor body is shaped to protruding rotor hub portions 10 having apertures 14 at their base portions for permanent magnet pieces 12 • · • · *! * Thus, the ferromagnetic plates have narrow edge portions on the permanent magnet side of the hub. 12 hubs are mounted in the circumferential direction of the rotor and between the permanent magnet pieces To support the anchor 10, a support rail 16 extends to the shaft-side rotor body portion 18 and the hub portion 10 of the permanent magnets. The support rail 16 is the entire length of the rotor and is made of non-ferritic steel.

Radial cooling ducts 22 are provided in the rotor for passing cooling air through the rotor body from its inner side surface to the outer circumference of the rotor into the air gap of the electric machine.

Fig. 2 is a partial enlargement Z of Fig. 1 and shows in more detail how a shallow groove 26 is machined into the top surface of the channel 14 for permanent magnet pieces. The groove extends through the entire rotor magnet line from rotor to end. The lower grooves 26 are fitted with rotor plate pack mounting sticks or rails 28. The mounting stick 28 is threaded between each adjacent permanent magnet piece 12 through a hole 31 in the play piece 30, whereby the play piece 30 holds the permanent magnet pieces 12 in longitudinal direction. The mounting stick 28 is secured at both ends to the rotor end plate 32, which also supports the outermost permanent magnet piece.

The clearance piece 30 is, in the embodiment of Figure 2, a baffle or prick having the same thickness as the radial air channel width of the rotor and having a diameter that is so large that. . it holds the permanent magnet pieces in place. This allows the radial air duct to remain open for the most part, also for permanent magnet pieces, and the cooling air to flow freely across the entire cross sectional surface of the rotor. The clearance piece reliably prevents permanent magnet pieces • «· ·« ·. ··· from sliding out and clogging the radial cooling channel with the rotor or electric • · · «·. ·. 20 while making or moving a machine. If the permanent magnet pieces 12 and them * · ♦ ·. ·· *. the gap between the apertures 14 is further sealed with a resin which partially secures the permanent ··· magnetic pieces 12, preventing the clearance piece from moving the permanent magnet pieces even though the resin; * · For some reason, would weaken or not evenly spread everywhere.

·· • · · • · * ♦

In the manufacture of the rotor, the solution according to the invention facilitates and enhances especially the middle · * • ·! 25 Tact magnet pieces in place. Once the rotor plate package has been assembled and fitted to the shaft, the mounting sticks 28 are inserted into their respective grooves 26. The permanent magnet pieces are then inserted at the end of the root torque so that they correspond to the mounting sticks * * protruding slightly from the surface of the opening 14 for the permanent magnet piece.

Thus, the coating protecting the permanent magnet piece does not touch the disc pack and will not be scratched or otherwise damaged during installation. The coating, which is particularly important for corrosion protection, thus remains intact. When the permanent magnet pieces are in place, the mounting stick 28 5 118839 is pulled out of its groove and re-inserted, while inserting the play pieces between the permanent magnet pieces.

The shape and position of the mounting stick and the play piece may vary within the scope of the invention. Figure 3 illustrates a machine axial solution having two grooves 26 and two mounting pins 28 mounted on the machine axis 4 side of a permanent magnet channel 14. In this embodiment, there is only one permanent magnet piece 42 in the circumferential direction of the hub. is mounted on two mounting pins 28. The clearance piece 31 is oval in this embodiment, whereby the air flow in the radial duct is uniform.

According to an embodiment of the invention according to Fig. 4, a groove 33 is formed in the permanent magnet piece 44 for the mounting stick 28. The permanent magnet piece is also coated at the groove so that the protection is maintained.

In the embodiment shown in Figure 5, a hole 34 is drilled in the permanent magnet block 46 and the mounting stick 36 is guided through the hole. This avoids the step of machining the rotor body 15, but the mounting stick 36 cannot be used as a sliding surface when moving the permanent magnet pieces.

In the embodiment shown in Fig. 6, a hole 35 is drilled below the permanent magnet block 47 and the mounting stick 37 is guided through the hole. The clearance piece 39 is shaped such that it extends well between the permanent magnet pieces and is mounted on the mounting stick so that it remains in the correct position to lock the permanent magnet pieces in the axis of the machine.

From the side shown in Fig. 7, another permanent magnet block 38 is attached to its ends or otherwise provided with a clearance piece 40. In this case, the mounting stick is not needed at all, but also the advantages it brings.

The invention has been described above with reference to some embodiments thereof. However, the disclosure is not to be construed as limiting the scope of the patent, but embodiments may vary within the scope defined by the following claims.

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Claims (6)

6 118839 An arrangement for locking permanent magnet blocks (12) in an electrical machine comprising a plate pack (6) formed of ferromagnetic plates arranged on a rotor shaft (4), provided with channels (14) to which permanent magnet blocks (12) can be fitted, (4) is provided with at least two successive permanent magnet pieces (12), a gap piece (30) disposed between two successive permanent magnet pieces (12) which prevents the permanent magnet pieces (12) from moving in the direction of the electrical machine shaft (4), characterized in that A mounting stick (28) parallel to the shaft (4) can be inserted through (30) and that - a groove (33) is formed on the plane surface of the permanent magnet block (44) or the permanent magnet blocks (46) have a hole (34) , or - grooves 15 (26) are formed in the channels (14) provided for the permanent magnets, or a the hub on which the dowel pin (28) can be fitted. Arrangement according to Claim 1, characterized in that the permanent magnets (12) are. : Can be tagged along the surface of the mounting stick (28) when installing permanent magnets. Arrangement according to Claim 1 or 2, characterized in that the mounting stick (28) is slidable in the direction of the longitudinal axis of the electrical machine and the clearance pieces (30) are mounted. between the permanent magnet pieces (12) when the mounting stick (28) has been pulled to the side of the respective clearance • * »• · · **; piece (30). Arrangement according to one of Claims 1 to 3, characterized in that the mounting pin (28) and the clearance piece (30) are of non-ferritic material. · A • «• · • · .2 25 Arrangement according to Claim 1, characterized in that, when the mounting stick is • aa · · · · (fitted in an opening adjacent to the permanent magnet pieces, the clearance piece extends radially over the distance between the mounting stick and the permanent magnet piece as defined by the rotors for the axial line. • · • · ··· 7 118839 Arrangement according to Claim 1, characterized in that the mounting stick (28) is attached to an end plate (32) at the end of the electrical machine. • • • • • • • • • • • • • • • • • • • • •••••••••••• · »• • • * •« «• · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ··· · 118839