JP7620261B2 - Motor rotor and manufacturing method thereof - Google Patents

Description

The present invention relates to improvements to the motor rotor that constitutes the motor.

One example of a conventional motor rotor is described in Patent Document 1. The motor core described in Patent Document 1 is made by stacking multiple core plates and has a through hole that houses a permanent magnet. Inside the through hole, a fixed piece and a recess are formed in a selected core plate. The motor core houses a permanent magnet in the through hole, and the fixed piece is bent into the recess and pressed against the permanent magnet, thereby fixing the permanent magnet in the through hole.

JP 2011-172441 A

In recent years, the use of thin plates such as amorphous materials for the core plates of motor rotors has been considered in order to improve motor performance. However, conventional motor rotors have a structure in which the fixed piece is bent and pressed against the permanent magnet, i.e., the permanent magnet is fixed by crimping, which poses the problem that it is difficult to use brittle materials such as amorphous materials for the core plate, and solving this problem has been an issue.

The present invention was made with a focus on the above-mentioned conventional problems, and aims to provide a motor rotor and a manufacturing method thereof that can sufficiently fix permanent magnets even when a thin plate of amorphous material or the like is used for the core plate, thereby contributing to improved motor performance.

The motor rotor according to the present invention comprises a core material formed by stacking a number of core plates and having through holes passing through in the stacking direction, and permanent magnets housed in the through holes, and the motor rotor is characterized in that the permanent magnets have recesses on their sides that are open at least in the direction around the rotor axis, some of the core plates engage with the recesses , and the engagement points between the core plates and the recesses are provided on the rotor axis side of the permanent magnets and at positions symmetrical with respect to the center line of the permanent magnets that coincides with the radial direction of the core material .

The manufacturing method of the motor rotor according to the present invention is characterized in that, when manufacturing the motor rotor, a through hole and a through hole that opens in the stacking direction of the core plates are formed in the core material, a permanent magnet is placed in the through hole of the core material, and then a jig is inserted into the through hole to press some of the multiple core plates in the direction around the rotor axis to engage them with the recesses.

By adopting the above-described configuration, the motor rotor and manufacturing method thereof according to the present invention are able to sufficiently fix the permanent magnets even when a thin plate of amorphous material or the like is used for the core plate, and can suppress damage to the permanent magnets 5 due to centrifugal force , thereby contributing to improved motor performance.

FIG. 1 is a plan view illustrating a quarter portion of a motor rotor according to a first embodiment of the present invention. 2A is a perspective view illustrating the permanent magnet shown in FIG. 1 , and FIG. 2B is a perspective view showing another example of a recess of the permanent magnet. 2A is a cross-sectional view of a main part based on the arrows along line AA in FIG. 1, in which (A) shows a state in which a permanent magnet is accommodated, and (B) is a cross-sectional view showing a state in which the permanent magnet is fixed. 4A to 4D are plan views illustrating a core plate applicable to the first embodiment. 11A is a cross-sectional view illustrating a state in which a permanent magnet is accommodated in a motor rotor according to a second embodiment of the present invention; FIG. 11B is a cross-sectional view illustrating a state in which the permanent magnet is fixed; FIG. 13A to 13F are plan views illustrating a core plate applicable to a second embodiment.

First Embodiment
The motor rotor 1 shown in Fig. 1 constitutes a motor together with a stator (not shown) arranged on the outer periphery, and rotates about a rotor shaft Cr. The motor rotor 1 includes a core material 4 formed by stacking a plurality of core plates 2 and having through holes 3 penetrating in the stacking direction, and a permanent magnet 5 accommodated in the through holes 3.

As shown in FIG. 2A, the permanent magnet 5 has a recess 6 on its side that is open at least in the direction around the rotor shaft (direction of arrow R). The motor rotor 1 has a structure in which some of the core plates 2 are engaged with the recess 6. In this embodiment, some of the core plates 2 are engaged with the recess 6 while being shifted in the direction around the rotor shaft (direction of arrow R).

The core material 4 has holes 3 at regular intervals along its periphery, and also has a number of through holes 7 that are open in the lamination direction of the core plate 2. The permanent magnet 5 in the illustrated example is a rectangular flat plate, and is housed in the hole 3 with the long side of its main surface aligned with the lamination direction of the core plate 2. If necessary, the core material 4 may be laminated with other core materials to form a laminate, and end plates and a rotating shaft may be attached above and below the laminate.

When the permanent magnet 5 is placed in the through hole 3, multiple recesses 6 (three in the illustrated example) are formed at a predetermined interval at the corner between the main surface facing the rotor shaft Cr and one of the two side surfaces. As a result, the recesses 6 are open at least in the direction around the rotor shaft, and are also open to the rotor shaft Cr side.

Next, the rotor motor 1 and a manufacturing method thereof will be described with reference to FIG.
That is, in the manufacturing method of the rotor motor 1, as shown in Fig. 3(A), a plurality of core plates 2 are stacked, and then permanent magnets 5 are housed in the through holes 3. Next, in the manufacturing method, as shown in Fig. 2(B), some of the plurality of core plates 2, more specifically, the core plates 2 at positions corresponding to each recess 6 of the permanent magnet 5, are shifted in the direction around the rotor axis.

In this case, the manufacturing method uses a jig 8 that is inserted into the through hole 7 near the through hole 3. As shown in FIG. 2(B), this jig 8 has a body 8A with protrusions 8B that correspond to the positions of each recess 6. After being inserted into the through hole 3, each protrusion 8B presses the corresponding core plate 2 and moves it around the rotor shaft. This causes a portion of the core plate 2 to engage with each recess 6.

In this way, in the motor rotor 1 and its manufacturing method, the permanent magnets 5 are fixed in the through holes 3 in the core material 4. For ease of understanding, the drawings show one core plate 2 engaged with each recess 6. However, when a thin plate made of amorphous material is used for the core plate 2, it is not easy to engage one core plate 2 with one recess 6 because the plate thickness is about 0.1 mm. In such a case, each of the illustrated core plates 2 can be replaced with a core plate group (2) made of multiple core plates 2, and the core plate group (2) is engaged with each recess 6 to fix the permanent magnets 5.

The motor rotor 1 and its manufacturing method described above can secure the permanent magnets 5 without bending the core plate 2, compared to the conventional method of securing the permanent magnets by crimping the core plate. Therefore, even if a thin plate made of a brittle material such as an amorphous material is used for the core plate, the permanent magnets 5 can be secured sufficiently, which contributes to improving the performance of the motor.

In addition, the motor rotor 1 and its manufacturing method described above have a structure in which the core plate (core plate group) 2 and the permanent magnet 5 mesh together, so the permanent magnet 5 can be fixed more firmly than in a structure that maintains a fixed state by frictional force, such as with crimping, and the laminated portion between adjacent recesses 6 can be sufficiently fixed.

Furthermore, in conventional structures where the permanent magnet is fixed by crimping the core plate, a space is required inside the through hole to accommodate the deformed portion of the core plate. In contrast, in the above-mentioned motor rotor 1 and its manufacturing method, when the core plate 2 is moved around the rotor axis, as shown in Figure 1 (B), a gap S is generated between the moved core plate 2 and the permanent magnet 5, but this gap S is extremely small, about the depth of the recess 6.

In the above motor rotor 1 and its manufacturing method, the position, number, and shape of the recesses 6 of the permanent magnet 5 are not limited to those in the above embodiment, and it is also possible to adopt, for example, either or both of the recesses 6A and 6B shown in FIG. 2(B). The recess 6A shown on the upper side in FIG. 2(B) is a groove formed along the plate thickness direction of the permanent magnet 5, and is entirely open in the direction around the rotor shaft. The recess 6B shown on the lower side in FIG. 2(B) is a groove formed within a certain range in the direction around the rotor shaft from the end on the rotor shaft Cr side surface of the permanent magnet 5, and is open in the direction around the rotor shaft at the end.

In addition, in the above motor rotor 1 and its manufacturing method, the shape of the core plate 2 that engages with the recess 6 formed in the permanent magnet 5 can be appropriately selected depending on the shape of the recess 6. For example, two types of core plates 2A and 2B as shown in Figures 4(A) and (B) can be used for the motor rotor 1 of this embodiment.

The first core plate 2A shown in FIG. 4(A) corresponds to the recessed portion 6, has an opening H for forming the through hole 3, and is immobile when engaged with the permanent magnet 5. The second core plate 2B shown in FIG. 4(B) corresponds to the recessed portion 6 of the permanent magnet 5, and also has an opening H, and has a protrusion 2P on the edge of the opening H that becomes the engaging portion for the recessed portion 6, and moves when engaged with the permanent magnet 5. When the core plates 2A and 2B are stacked, the openings H communicate with each other to form the through hole 3.

When the core plates 2A and 2B are stacked on top of each other, the second core plate 2B is pre-shifted so that the permanent magnet 5 and the protruding piece 2P do not interfere with each other in the through hole 3, as shown in FIG. 4(C). After the permanent magnet 5 is placed in the through hole 3, the second core plate 2B is moved in the direction opposite to the initial shift direction, so that the protruding piece 2P of the second core plate 2B engages with the recess 6 of the permanent magnet 5, and the permanent magnet 55 is fixed in the through hole 3. As a result, the entire openings H of all the core plates 2A and 2B of the motor rotor 1 are aligned, realizing a structure without gaps S as shown in FIG. 3(B).

Second Embodiment
5 and 6 are diagrams illustrating a motor rotor according to a second embodiment of the present invention. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The motor rotor 1 shown in FIG. 5(A) has a permanent magnet 5 with multiple recesses 6 arranged in the lamination direction of the core plate 2. The permanent magnet 5 in the illustrated example has multiple recesses 6 at the corner between the main surface on the rotor shaft Cr side and one of its side surfaces (the left corner in the figure), and multiple recesses 6 at the corner between the main surface and the other side surface (the right corner in the figure). The number of recesses 6 on both sides is not limited, but they are provided at different positions in the lamination direction of the core plate 2.

As shown in FIG. 5(B), some of the core plates 2 of the motor rotor 1 engage with each recess 6 from one direction around the rotor shaft (arrow R1 direction). Also, some of the core plates 2 of the motor rotor 1 engage with other recess 6 from the other direction around the rotor shaft (arrow R2).

The motor rotor 1 of this embodiment can use three types of core plates 2A, 2B, and 2C, as shown in Figures 6(A) to (C). The first core plate 2A shown in Figure 6(A) corresponds to a portion other than the recess 6, has an opening H for forming the through hole 3, and is immobile when engaged with the permanent magnet 5.

The second core plate 2B shown in FIG. 6(B) corresponds to the recess 6 on one side of the permanent magnet 5, and also has an opening H, and has a protrusion 2P on the edge of the opening H that engages with the recess 6. The third core plate 2C shown in FIG. 6(C) corresponds to the recess 6 on the other side of the permanent magnet 5, and also has an opening H, and has a protrusion 2Q on the edge of the opening H that engages with the recess 6, at a position symmetrical to the protrusion P of the second core plate 2B. The openings H communicate with each other to form the through holes 3 when the core plates 2A to 2C are stacked.

When the core plates 2A to 2C are stacked on top of each other, the second and third core plates 2B and 2C are offset in advance in opposite directions so that the permanent magnets 5 and the protrusions 2P and 2Q do not interfere with each other inside the through holes 3, as shown in FIG. 6(D).

After the permanent magnet 5 is placed in the through hole 3, the second core plate 2B is moved in the direction opposite to the initial misalignment (the direction of the arrow R1) as shown in FIG. 6(E), and the protruding piece 2P of the second core plate 2B is engaged with the recess 6 on one side of the permanent magnet 5.

Next, as shown in FIG. 6(F), the third core plate 2C is moved in the direction opposite to the initial displacement (the direction of the arrow R2) to engage the protruding piece 2P of the second core plate 2B with the recess 6 on the other side of the permanent magnet 5. This causes the motor rotor 1 to fix the permanent magnet 5 in the through hole 3. It is also possible to move the second and third core plates 2B and 2C simultaneously.

In this way, the motor rotor 1 described above can adequately fix the permanent magnets 5 even when a thin plate made of a brittle material such as an amorphous material is used for the core plate 2, as in the first embodiment. In particular, by constraining the permanent magnets 5 on both sides, the fixing force can be further increased, which contributes to improving the performance of the motor.

The motor rotor 1 is configured such that the engagement points between the core plate 2 and the recessed portion 6 are located on the rotor shaft side of the permanent magnet 5 and symmetrically with respect to the center line Cm of the permanent magnet 5, which coincides with the radial direction of the core material 4. In short, the motor rotor 1 is configured such that the engagement points between the core plate 2 and the recessed portion 6 are located at both ends of the rotor shaft side of the permanent magnet 5.

The motor rotor 1 described above has improved durability against the centrifugal force generated at the center of gravity of the permanent magnet 5 due to rotation. In other words, when the motor rotor 1 rotates, as shown in FIG. 6(F), a centrifugal force F1 is generated at the center of gravity of the permanent magnet 5, and the permanent magnet 5 receives a reaction force F2 from the core material 4. At this time, the permanent magnet 5 may be damaged if a bending moment or a non-uniform, locally excessive load occurs.

The motor rotor 1 has a structure in which the restraining point of the permanent magnet 5 in the core material 4 is one surface, multiple surfaces, or a point that is symmetrical with respect to the direction of the centrifugal force F1 (center line Cm). As a result, the motor rotor 1 restrains the permanent magnet 5 at a point that is symmetrical with respect to the center of gravity of the permanent magnet 5, thereby suppressing damage to the permanent magnet 5 due to centrifugal force and improving durability. Furthermore, improving the durability of the permanent magnet 5 can contribute to improving the maximum rotation speed of the motor, making it possible to reduce the size of the motor.

The configuration of the motor rotor according to the present invention is not limited to the above-mentioned embodiments, and can be modified as appropriate without departing from the spirit of the present invention. The above-mentioned motor rotor can also be applied to the rotor of a generator, which has a substantially equivalent configuration to that of a motor.

Reference Signs List 1 Motor rotor 2 Core plate 2 A to 2C Core plates 3 Through hole 4 Core material 5 Permanent magnet 6 Recess 7 Through hole 8 Jig

Claims (3)

A core material formed by laminating a plurality of core plates and having a through hole passing through in the lamination direction;
A motor rotor having a permanent magnet housed in the through hole,
the permanent magnet has a recess on a side surface thereof that is open at least in a direction around the rotor axis,
Some of the core plates are engaged with the recesses ,
A motor rotor characterized in that the engagement point between the core plate and the recess is located on the rotor shaft side of the permanent magnet and in a position symmetrical with respect to the center line of the permanent magnet which coincides with the radial direction of the core material . the permanent magnet has a plurality of recesses arranged in a lamination direction of the core plate,
Some of the core plates are engaged with the recesses from one direction around the rotor shaft,
2. The motor rotor according to claim 1, wherein another part of the plurality of core plates engages with another of the recesses from another direction around the rotor axis. When manufacturing the motor rotor according to claim 1,
the core material has the through hole and a through hole that is open in the lamination direction of the core plate,
After the permanent magnet is accommodated in the through hole of the core material,
A method for manufacturing a motor rotor, comprising the steps of: pressing some of the plurality of core plates in a direction around the rotor axis using a jig inserted into the through hole to engage with the recess;

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