JP6748615B2 - Rotor for rotating electric machine - Google Patents

Description

The present invention relates to a rotor for rotary electric machines.

2. Description of the Related Art Conventionally, there is known a rotor provided in a rotating electric machine such as a motor, in which a cylindrical balance adjusting member for adjusting an unbalance of rotation is fixed to a rotating shaft. For example, the rotational imbalance is adjusted by shaving the outer peripheral surface of the balance adjusting member or adding putty.

JP, 2010-200440, A

However, in the conventional technology, when the rotor is rotated, a loss of rotation due to air resistance (so-called wind loss) occurs due to the uneven shape of the adjusted portion, or scraps or putty of the adjusted portion is generated. The parts may be scattered around. As described above, in the conventional rotor, the performance of the motor may be deteriorated.

The present invention has been made in view of the above, and an object of the present invention is to provide a rotor for a rotary electric machine that can prevent the performance of the motor from being deteriorated.

In order to solve the above-mentioned problems and to achieve the object, a rotor for a rotary electric machine according to an aspect of the present invention includes a magnet, a balance adjusting unit, a pair of bearing units, and a cover. The magnet is provided on the outer peripheral surface of the rotating shaft. The balance adjustment portion is tubular and is provided on the end side in the rotation axis direction of the magnet, and an adjustment portion for adjusting the rotation balance is formed on the outer peripheral surface. The pair of bearing portions are provided at positions sandwiching the magnet and the balance adjusting portion in the rotation axis direction, and rotatably support the rotation shaft. The cover has a tubular shape, extends along the outer peripheral surface of the balance adjustment portion in the rotation axis direction, and covers the adjustment portion of the balance adjustment portion. The magnet has a tubular shape. The cover covers the outer peripheral surface of the magnet. The outer diameter of the cover is smaller than the inner diameter of the outer ring portion of the pair of bearing portions. At least one of the cover is Mashimashi inner portion or in extension of the bearing portion of said pair are in contact.

According to one aspect of the present invention, it is possible to provide a rotor for a rotary electric machine that can prevent the performance of the motor from being degraded.

FIG. 1 is a side view of the motor according to the embodiment. FIG. 2 is a cross-sectional view of the rotor according to the embodiment. FIG. 3 is a cross-sectional view of the rotor according to the embodiment. FIG. 4 is a diagram showing the relationship between the presence or absence of a cover and the no-load current value. FIG. 5 is a diagram showing the relationship between the specific gravity of the cover and the allowable imbalance of the rotor. FIG. 6 is a sectional view of a rotor according to a modified example of the embodiment.

Hereinafter, a rotor for a rotary electric machine according to an embodiment will be described with reference to the drawings. Note that the dimensional relationship of each element in the drawings, the ratio of each element, and the like may differ from reality. Even between the drawings, there may be a case where the dimensional relationships and ratios are different from each other. In the following, an inner rotor type brushless motor will be described as an example of the rotating electric machine.

First, the motor according to the embodiment will be described with reference to FIG. FIG. 1 is a side view of a motor 1 according to the embodiment.

The motor 1 according to the embodiment includes a rotor 2 and a stator 3. The rotor 2 is a rotor of the motor 1, and includes a rotating shaft 21 and bearing portions 22a and 22b. The rotor 2 is a so-called inner rotor type that faces the inner peripheral surface of the stator 3. The rotor 2 further includes a magnet 23, a cover 26, and the like, which will be described later with reference to FIG.

The bearings 22a and 22b are, for example, ball bearings, are fixed to the outer peripheral surface of the rotary shaft 21, and rotatably support the rotary shaft 21. Specifically, the pair of bearings 22a and 22b are provided at positions where the magnet 23 (see FIG. 2) and the balance adjusting parts 24 and 25 (see FIG. 2) are sandwiched between them in the rotation axis direction. The bearings 22a and 22b are not limited to rolling bearings such as ball bearings, but may be bearings of other structures such as slide bearings and magnetic bearings.

The stator 3 is a stator in the motor 1, and is a cylindrical member formed by stacking a plurality of plate-shaped metal members such as soft magnetic steel plates such as silicon steel plates and electromagnetic steel plates. Further, the stator 3 is provided with a plurality of teeth, which are evenly arranged along the circumferential direction, and each of which faces the rotor 2 and which faces the rotor 2 and coils which are not shown and are wound around the teeth.

Next, the rotor 2 according to the embodiment will be further described with reference to FIG. FIG. 2 is a cross-sectional view of the rotor 2 according to the embodiment. As shown in FIG. 2, the rotor 2 further includes a magnet 23, balance adjusting portions 24 and 25, and a cover 26.

The magnet 23 is a cylindrical permanent magnet, and is provided on the outer peripheral surface of the rotating shaft 21. Specifically, the inner peripheral surface of the magnet 23 is fixed to the outer peripheral surface of the rotating shaft 21 by, for example, an adhesive member. As the magnet 23, for example, a ferrite magnet or a neodymium magnet can be used.

The balance adjustment parts 24 and 25 are non-magnetic metal materials such as brass and stainless steel, and are cylindrical members that adjust the unbalance of rotation of the rotor 2. The balance adjustment parts 24 and 25 are provided on the end side of the magnet 23 in the rotation axis direction, and adjustment parts 24a and 25a for adjusting the rotation balance are formed on the outer peripheral surface. For example, the balance adjusting parts 24 and 25 are fixed by being in contact with both end surfaces of the magnet 23. Specifically, the balance adjusting parts 24 and 25 have their inner peripheral surfaces fixed to the outer peripheral surface of the rotating shaft 21 by, for example, an adhesive member, and rotate in accordance with the rotating operation of the rotating shaft 21.

The balance adjusters 24 and 25 are members that adjust the rotational balance by a so-called negative balance, in which the adjustment parts 24a and 25a are recessed. Specifically, the concave adjustment portions 24a and 25a are formed by excavating the outer peripheral surface in the radial direction.

The balance adjusting parts 24 and 25 are not necessarily provided on both end surfaces of the magnet 23, that is, so-called two-sided balance, and may be provided on only one end surface of the magnet 23.

The cover 26 is provided after the balance adjustment of the balance adjustment units 24 and 25 (after the adjustment portions 24a and 25a are formed), and is made of, for example, a material having a relatively small specific gravity, for example, a metal such as aluminum or a resin such as plastic. It is a member.

Specifically, the cover 26 extends in the rotation axis direction along the outer peripheral surfaces of the balance adjusting portions 24 and 25 and covers the adjusting portions 24a and 25a of the balance adjusting portions 24 and 25. Further, the cover 26 covers the outer peripheral surface of the magnet 23. The cover 26 may cover the entire outer peripheral surface of the magnet 23 or a part of the outer peripheral surface in the rotation axis direction. The cover 26 is sandwiched by the pair of bearings 22a and 22b, and details of this point will be described later with reference to FIG.

Here, a conventional cover will be described. The conventional cover is provided at a position that does not cover the adjustment portion of the balance adjustment unit. Therefore, when adjusting the rotational balance, a part of the outer peripheral surface of the balance adjusting portion which is not covered with the cover is cut or a putty is added.

However, conventionally, when the motor is rotated, the wind loss (loss due to air resistance) is large due to the uneven shape of the adjustment part, and the material such as shavings and putty of the adjustment part is scattered around. As a result, the performance of the motor may decrease.

Therefore, the cover 26 according to the embodiment is provided at a position that covers the adjustment parts 24a and 25a. As a result, it is possible to reduce windage loss that occurs when the motor 1 rotates, and to prevent scattering of substances such as scraps and putties on the adjustment parts 24a and 25a. That is, it is possible to prevent the performance of the motor 1 from decreasing.

Further, as shown in FIG. 2, the cover 26 extends over the entire outer peripheral surfaces of the magnet 23 and the balance adjusting portions 24 and 25. That is, the cover 26 extends to each of the pair of bearings 22a and 22b. This point will be described with reference to FIG.

FIG. 3 is a cross-sectional view of the rotor 2 according to the embodiment. As shown in FIG. 3, the bearing portion 22a has an inner ring portion 22a1, and the inner ring portion 22a1 and the ball portion rotate together with the rotary shaft 21.

As shown in FIG. 3, the cover 26 has an end portion 26a fixed to the inner ring portion 22a1. Further, an end portion (not shown) opposite to the end portion 26a of the cover 26 is also fixed to the inner ring portion of the bearing portion 22b. That is, the cover 26 is sandwiched by the pair of bearings 22a and 22b. Therefore, it is not necessary to use an adhesive member or the like for fixing the cover 26. Therefore, it is possible to prevent the imbalance of the rotation from being caused by the manufacturing tolerance such as the variation in the coating amount of the adhesive member, and to prevent the manufacturing man-hour from increasing.

Although the cover 26 is sandwiched and fixed by the pair of bearings 22a and 22b, the inner peripheral surface of the cover 26 and the outer peripheral surface of the magnet 23 may be adhered and fixed by an adhesive member, for example.

Next, the relationship between the presence or absence of the cover 26 and the windage loss during rotation will be described with reference to FIG. FIG. 4 is a diagram showing the relationship between the cover 26 and the no-load current value. FIG. 4 shows a graph in which the vertical axis represents the no-load current value and the horizontal axis represents the rotation speed of the motor 1.

The graph of FIG. 4 shows the no-load current value of the motor 1 in the cases of “with cover” and “without cover”. “With a cover” indicates that the rotor 2 is provided with a cover 26 that covers the adjustment parts 24a and 25a. “Without cover” is a comparison target and indicates that the rotor 26 is not provided with the cover 26.

As shown in FIG. 4, when the number of revolutions is in the range of 30,000 to 100,000 min ⁻¹ , “with a cover” is a no-load current value when compared with “without a cover” at the same number of revolutions Is small. That is, the motor 1 according to the embodiment can reduce the windage loss by providing the cover 26.

Next, the specific gravity of the cover 26 will be described with reference to FIG. FIG. 5 is a diagram showing the relationship between the specific gravity of the cover 26 and the allowable imbalance of the rotor 2. Here, the allowable imbalance refers to a range of allowable balance, that is, an allowable amount of unbalance that does not affect the performance of the motor 1 during rotation.

In the graph shown in FIG. 5, when the specific gravity of the rotor 2 excluding the cover 26 is 7.0 and the weight of the rotor 2 is 1 g, the unbalance amount generated by adding the cover 26 is shown for each specific gravity. The cover 26 has a gap of 0.05 mm between the balance adjusting portions 24 and 25, and the thickness of the cover 26 itself is 0.3 mm.

Here, in the diagram showing the allowable residual ratio imbalance with respect to the balance goodness grade (FIG. 1 of JIS B 0905-1992), an electric motor (for example, motor 1) of 50,000 min ⁻¹ that satisfies the balance standard G6.3 is assumed. In that case, the allowable imbalance of the entire rotor 2 is 0.12 mgcm/g. When the allowable unbalance allowed by the cover 26 is halved, it becomes 0.06 mgcm/g.

Considering that the diameter of the rotor 2 of the motor 1 that can handle high-speed rotation is generally 15 mm or less, the cover 26 that satisfies the allowable unbalance amount 0.06 mgcm/g from the graph of FIG. The specific gravity of is preferably 3 or less.

In other words, it is preferable that the cover 26 has a ratio of the specific gravity of the cover 26 to the total specific gravity of the rotary shaft 21, the magnet 23, and the balance adjusting portions 24 and 25 of 3/7 or less. Accordingly, even when the cover 26 is provided on the rotor 2, it is possible to prevent the rotation from being unbalanced.

As a material having a specific gravity of 3 or less, there is aluminum (specific gravity 2.7), for example. Further, as shown in FIG. 5, the cover 26 preferably has a specific gravity of 2 or less. Materials having a specific gravity of 2 or less include carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP). As a result, even if the rotor 2 is smaller, it can be accommodated.

Next, another example of the cover 26 will be described with reference to FIG. FIG. 6 is a cross-sectional view of the rotor 2 according to the modified example of the embodiment. The cover 26 according to the modified example is different from the cover 26 according to the above-described embodiment in that it has a bottomed tubular shape.

Specifically, in the cover 26 according to the modified example, the end portion 26a is a bottom surface, and a through hole through which the rotary shaft 21 penetrates is formed in the bottom surface. The end 26b of the cover 26, which is opposite to the end 26a, contacts the balance adjusting unit 25 in the rotation axis direction.

Specifically, the balance adjusting portion 25 has a shape in which the end portion 25b on the bearing portion 22b side is projected in the radial direction, and the end portion 25b and the end portion 26b of the cover 26 are in contact with each other. More specifically, the cover 26 is fixed by the bearing portion 22b pressing the balance adjustment portion 25.

Thereby, for example, even if the inner ring portions 22a1 and 22b1 of the bearing portions 22a and 22b are relatively small, it is possible to cope with them without reducing the diameter of the cover 26 in accordance with the inner ring portion.

As described above, the rotary electric machine rotor 2 according to the embodiment includes the magnet 23, the balance adjustment units 24 and 25, and the cover 26. The magnet 23 is provided on the outer peripheral surface of the rotating shaft 21. The balance adjusting parts 24 and 25 are cylindrical and are provided on the end side in the rotation axis direction of the magnet 23, and adjusting parts 24a and 25a for adjusting the rotation balance are formed on the outer peripheral surface. The cover 26 has a tubular shape, extends in the rotation axis direction along the outer peripheral surfaces of the balance adjusting portions 24 and 25, and covers the adjusting portions 24a and 25a of the balance adjusting portions 24 and 25. As a result, it is possible to reduce windage loss that occurs when the motor 1 rotates, and to prevent scattering of substances such as shavings and putty of the adjustment parts 24a and 25a, so that the performance of the motor 1 can be prevented from deteriorating.

Moreover, in the rotor 2 for a rotary electric machine according to the embodiment, the magnet 23 has a tubular shape. Further, the cover 26 covers the outer peripheral surface of the magnet 23. Thereby, for example, even when a minute substance is scattered from the surroundings, the outer peripheral surface of the magnet 23 can be protected.

Further, the rotor 2 for a rotary electric machine according to the embodiment includes a pair of bearing portions 22a and 22b. The pair of bearing portions 22a and 22b are provided at positions where the magnet 23 and the balance adjusting portions 24 and 25 are sandwiched therebetween in the rotation axis direction, and rotatably support the rotation shaft 21. The cover 26 extends to each of the pair of bearings 22a and 22b. As a result, an adhesive member or the like is not required to fix the cover 26, so that it is possible to prevent imbalance in rotation from occurring, and it is possible to prevent the number of manufacturing steps from increasing.

Further, in the rotor 2 for a rotary electric machine according to the embodiment, the balance adjusting portions 24 and 25 have a shape in which the adjusting portions 24a and 25a are recessed. As a result, when the balance adjustment units 24 and 25 are in a negative balance, it is possible to reduce windage loss and prevent scattering, and thus it is possible to prevent the performance of the motor 1 from deteriorating.

Further, in the rotor 2 for a rotary electric machine according to the embodiment, the balance adjusting portions 24 and 25 are provided on both end surfaces of the magnet 23. Accordingly, when the balance adjusting units 24 and 25 are in a two-sided balance, wind loss can be reduced and scattering can be prevented, so that the performance of the motor 1 can be prevented from being deteriorated.

Further, in the rotor 2 for a rotary electric machine according to the embodiment, the cover 26 has a ratio of the specific gravity of the cover 26 to the total specific gravity of the rotating shaft 21, the magnet 23, and the balance adjusting units 24 and 25 of 3/7 or less. Accordingly, even when the cover 26 is provided on the rotor 2, it is possible to prevent the rotation from being unbalanced.

In the rotor 2 for a rotary electric machine according to the embodiment, the cover 26 has a specific gravity of 3 or less. This makes it possible to prevent imbalance in rotation due to the attachment of the cover 26.

In addition, in the above-described embodiment, the cover 26 is provided over the entire outer peripheral surfaces of the magnet 23 and the balance adjusting portions 24, 25. However, the cover 26 does not necessarily have to be provided over the entire outer peripheral surfaces and covers at least the adjustment parts 24a, 25a. I'll do it.

That is, the cover 26 does not have to cover the outer peripheral surface of the magnet 23 and the outer peripheral surfaces of the balance adjusting portions 24 and 25 other than the adjusting portions 24a and 25a. As a result, the weight of the rotor 2 can be reduced, and the rotation efficiency can be improved.

Further, the present invention is not limited to the above embodiment. The present invention also includes those configured by appropriately combining the constituent elements described above. Further, further effects and modified examples can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

1 Motor 2 Rotor 3 Stator 21 Rotating Shaft 22a, 22b Bearing 23 Magnet 24, 25 Balance Adjuster 24a, 25a Adjusting Part 26 Cover

Claims (5)

A magnet provided on the outer peripheral surface of the rotating shaft,
A cylindrical balance adjusting portion provided on the end side in the rotation axis direction of the magnet, and an adjusting portion for adjusting the rotation balance is formed on the outer peripheral surface,
A pair of bearing portions that are provided at positions sandwiching the magnet and the balance adjustment portion in the rotation axis direction and that rotatably support the rotation axis;
A cylindrical cover that extends in the rotation axis direction along the outer peripheral surface of the balance adjustment unit and covers the adjustment portion of the balance adjustment unit,
The magnet has a tubular shape,
The cover covers the outer peripheral surface of the magnet,
The outer diameter of the cover is smaller than the inner diameter of the outer ring portion of the pair of bearing portions,
At least one of the cover is Mashimashi inner portion or in extension of the bearing portion of said pair are in contact,
Rotor for rotating electric machine. The balance adjustment unit,
The rotor for a rotary electric machine according to claim 1, wherein the adjustment portion has a concave shape. The balance adjustment unit,
The rotor for a rotary electric machine according to claim 2, wherein the rotor is provided at both ends of the magnet. The cover is
The rotor for a rotary electric machine according to any one of claims 1 to 3, wherein a ratio of the specific gravity of the cover to the total specific gravity of the rotating shaft, the magnet, and the balance adjusting unit is 3/7 or less. The rotor for a rotary electric machine according to claim 4, wherein the cover has a specific gravity of 3 or less.

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