TWI535157B - Inner-rotor motor - Google Patents

Description

Inner rotor motor

The present invention relates to an inner rotor motor, and more particularly to an inner rotor motor that ensures smooth rotation of the rotor.

Referring to FIG. 1, a conventional inner rotor motor 9 is disclosed. The inner rotor motor 9 has a housing 91. The housing 91 is internally provided with a stator 92 and a rotor 93. The rotor 93 has a rotatable A rotating shaft 931 of the housing 91 is coupled to the outer peripheral surface of the rotating shaft 931, and a permanent magnet 932 is disposed. The permanent magnet 932 has an air gap between the stator 92 and the stator 92. The stator 92 can drive the rotor through the air gap. 93 rotation action. Similar to the detailed structural composition and actuation principle of the conventional inner rotor motor 9, it is disclosed in the invention patent of "Inner Rotor Motor" No. I371154 of the Republic of China.

However, if the rotor 93 of the conventional inner rotor motor 9 has problems such as asymmetrical shape, manufacturing tolerance, deformation, or uneven material distribution, the rotor 93 is prone to problems such as rotational imbalance during the rotation process, and thus causes vibration, such as vibration. Bad effects such as noise or motor function damage. Therefore, after the rotor 93 is manufactured and formed, the assembler must correct and test the balance state of the rotor 93 until the rotor 93 can reach the rotational balance, but the process of the calibration and test operation is not easy to operate, and is easy. There is a waste of manual assembly efficiency, and the accuracy of correction is not good, so it is necessary to improve.

The present invention provides an inner rotor motor mainly for at least one of permanent magnets A balance piece is placed at the end to ensure that the inner rotor motor stabilizes the rotator.

The above-mentioned inner rotor motor of the present invention can further facilitate the assembly and adjustment of the rotor by the assembler quickly and accurately.

The inner rotor motor of the present invention comprises: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances The permanent magnet is provided with a first end portion and a second end portion, and the permanent magnet is provided with a coupling hole penetrating the first end portion and the second end portion, and the rotating shaft is coupled to The plurality of balance sheets are respectively disposed on the first end portion and the second end portion.

The balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet.

Wherein, in the radial direction perpendicular to the axial direction of the rotation axis, the distance between the plurality of balance pieces in the circumferential direction is equal.

Wherein the plurality of balance pieces each have a pair of outer edges and an inner edge, the inner edge faces the coupling hole, the outer edge faces the outer peripheral surface of the permanent magnet, and has a radial direction perpendicular to an axial direction of the rotation axis In the direction, the outer edge does not extend beyond the outer surface of the permanent magnet.

The inner rotor motor of the present invention comprises: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances The permanent magnet is provided with a first end portion and a second end portion, and the permanent magnet is provided with a coupling hole penetrating the first end portion and the second end portion, and the rotating shaft is coupled to The bonding hole, the plurality of balance sheets are disposed at the first end portion, Each of the plurality of balance pieces has a pair of outer edge and an inner edge, the inner edge facing the coupling hole, the outer edge facing the outer circumferential surface of the permanent magnet, in a radial direction perpendicular to an axial direction of the rotation axis The outer edge does not extend beyond the outer surface of the permanent magnet.

The balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet.

Wherein, in the radial direction perpendicular to the axial direction of the rotation axis, the distance between the plurality of balance pieces in the circumferential direction is equal.

The outer edge of the plurality of balance pieces is adjacent to the outer peripheral surface of the permanent magnet.

The balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet.

Wherein, in the radial direction perpendicular to the axial direction of the rotation axis, the distance between the plurality of balance pieces in the circumferential direction is equal.

Wherein, the peripheral edge of the coupling hole of the permanent magnet is provided with a ring flange, and the outer edge of the plurality of balance pieces is adjacent to the outer peripheral surface of the permanent magnet, and the inner edge is connected to the ring flange.

The balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet.

Wherein, in the radial direction perpendicular to the axial direction of the rotation axis, the distance between the plurality of balance pieces in the circumferential direction is equal.

The inner rotor motor of the present invention comprises: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances a sheet; wherein the balance sheet is made of a magnetic material and integrally formed at an end of the permanent magnet.

The permanent magnet is provided with a first end portion and a second end portion. The permanent magnet is provided with a coupling hole penetrating the first end portion and the second end portion, and the rotating shaft is coupled to the joint. The holes, the plurality of balance sheets are disposed at the first end.

The inner rotor motor of the present invention comprises: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances a sheet; wherein, in a radial direction perpendicular to an axial direction of the rotation axis, the distance between the plurality of balance pieces in the circumferential direction is equal.

The permanent magnet is provided with a first end portion and a second end portion. The permanent magnet is provided with a coupling hole penetrating the first end portion and the second end portion, and the rotating shaft is coupled to the joint. The holes, the plurality of balance sheets are disposed at the first end.

The inner rotor motor of the present invention comprises: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances The permanent magnet is provided with a first end portion and a second end portion, and the permanent magnet is provided with a coupling hole penetrating the first end portion and the second end portion, and the rotating shaft is coupled to The plurality of balance pieces are disposed at the first end portion, and a first axial height between the first end and the second end of the permanent magnet is in an axial direction of the rotating shaft The plurality of balance pieces each have a second axial height, and the second axial height is 0.1 to 0.5 times the first axial height.

Wherein, in the axial direction of the rotating shaft, the first end portion to the second end portion of the permanent magnet have a first axial height, and the plurality of balance pieces located at the first end each have a a second axial height, the plurality of balance pieces at the second end each having a third axial direction The height, the sum of the second axial height and the third axial height is 0.1 to 0.5 times the first axial height.

Wherein, in the axial direction of the rotating shaft, the first end portion to the second end portion of the permanent magnet have a first axial height, and the plurality of balance pieces located at the first end each have a a second axial height, the plurality of balance pieces at the second end each having a third axial height, wherein the sum of the second axial height and the third axial height is the first axial height 0.15~0.4 times.

It can be seen from the above that the inner rotor motor of the present invention can ensure that the rotor is not easily offset and swayed when the rotor rotates by using the balance plate design of the permanent magnet, so that the rotor can achieve better balance rotation effect; The purpose of balance adjustment work can be achieved to improve the accuracy of correction and the convenience of correction.

〔this invention〕

1‧‧‧Shell

1a‧‧‧First housing

1b‧‧‧ second housing

11‧‧‧ accommodating space

12‧‧‧ pivotal department

2‧‧‧stator

3‧‧‧Rotor

31‧‧‧Rotary axis

32‧‧‧ permanent magnet

32a‧‧‧First end

32b‧‧‧second end

321‧‧‧ Balance film

321a‧‧‧ outer edge

321b‧‧‧ inside edge

322‧‧‧bond hole

323‧‧‧ring flange

‧‧‧‧ angle

H1‧‧‧First axial height

H2‧‧‧second axial height

H3‧‧‧3rd axial height

[study]

9‧‧‧Inner rotor motor

91‧‧‧Shell

92‧‧‧ Stator

93‧‧‧Rotor

931‧‧‧Rotary axis

932‧‧‧ permanent magnet

Fig. 1 is a sectional view showing a combination of a conventional inner rotor motor.

Fig. 2 is a sectional view showing the assembly of the inner rotor motor of the present invention.

Fig. 3 is a perspective view showing the rotor of the inner rotor motor of the first embodiment of the present invention.

Fig. 4 is a perspective view showing the rotor of the inner rotor motor of the second embodiment of the present invention.

Fig. 5 is a perspective view showing the rotor of the inner rotor motor of the third embodiment of the present invention.

Figure 6 is a plan view (1) of the rotor of the inner rotor motor of the present invention.

Figure 7 is a plan view (2) of the rotor of the inner rotor motor of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; The inner rotor motor of the present invention comprises a housing 1, a stator 2 and a rotor 3. Wherein the housing 1 is adapted to combine the stator 2 and the rotor 3, the stator 2 It is used to drive the rotor 3 to rotate.

The housing 1 is provided with an accommodating space 11 for coupling the stator 2, and the housing 1 is provided with at least one pivoting portion 12 for the rotor 3 to rotatably couple the housing by the pivoting portion 12. The seat 1, wherein the housing 1 can be a variety of hollow housing designs for the combination of the stator 2 and the rotor 3, the invention is not limited. In this embodiment, the housing 1 can include a first housing 1a and a second housing 1b. The first housing 1a and the second housing 1b can be combined with each other to form the housing 1. The first The housing 1a and the second housing 1b are each provided with a pivoting portion 12, and the two pivoting portions 12 have a spacing therebetween for assembly of the rotor 3.

The stator 2 is coupled to the accommodating space 11 of the housing 1 , and the stator 2 can be fixed in the accommodating space 11 of the housing 1 by means of a tight fit, a locking or a snap, etc., which is not limited by the present invention. .

The rotor 3 includes a rotating shaft 31 and a permanent magnet 32. The rotating shaft 31 is rotatably coupled to the pivoting portion 12 of the housing 1, and at least one end of the rotating shaft 31 can extend through the housing 1. external. For example, the rotating shaft 31 can be extended to the outside of the housing 1 at one end. Alternatively, the rotating shaft 31 can extend beyond the two ends of the housing 1 and is not limited by the present invention. The permanent magnet 32 can be coupled to the rotating shaft 31. The permanent magnet 32 can be fixed to the rotating shaft 31 by locking, clamping, bonding, tight fitting or welding, and the permanent magnet 32 and the stator 2 described above. An air gap is provided between the stator 2 to generate an alternating magnetic field through the air gap to drive the rotor 3 to rotate.

Further, at least one end portion of the permanent magnet 32 of the rotor 3 is provided with a plurality of balance pieces 321 which may be made of a magnetic material, and the balance is made in the process of manufacturing the permanent magnet 32 from a magnetic material. The sheet 321 can be integrally molded directly on at least one end portion of the permanent magnet 32 to improve manufacturing convenience, and the rotor 3 can be stably rotated by the plurality of balance sheets 321. Preferably, in the radial direction perpendicular to the axial direction of the rotating shaft 31, the distance between the plurality of balance pieces 321 in the circumferential direction may be equal to provide a better balanced rotation. effect.

Based on the balance piece 321 of the permanent magnet 32 described above, the permanent magnet 32 of the rotor 3 of the inner rotor motor of the present invention may comprise the following several different embodiments. Referring to FIG. 3, the permanent magnet 32 is provided with a first end portion 32a and a second end portion 32b, and the permanent magnet 32 is disposed through the first end portion 32a and the second end portion. a coupling hole 322 of the 32b, the coupling hole 322 is coupled to the rotating shaft 31, the plurality of balance pieces 321 are disposed on the first end portion 32a, and the plurality of balance pieces 321 each have a opposite outer edge 321a and An inner edge 321b faces the coupling hole 322, and the outer edge 321a faces the outer circumferential surface of the permanent magnet 32. Wherein, in the radial direction perpendicular to the axial direction of the rotating shaft 31, the outer edge 321a is preferably not beyond the outer peripheral surface of the permanent magnet 32, so as to avoid increasing the radial width of the permanent magnet 32, and further The weight of the inner rotor motor of the present invention is effectively reduced, and the plurality of balance pieces 321 are preferably coupled adjacent to the outer circumferential surface of the permanent magnet 32, so that the balance balance effect of the plurality of balance pieces 321 is better, so that the rotor 3 can be For example, in this embodiment, the outer edge 321a is adjacent to the outer peripheral surface of the permanent magnet 32. The inner edge 321b is not connected to the coupling hole 322, and the plurality of balance pieces 321 are The number of the balance pieces 321 has an angle α between each other, and the angle α is ninety degrees, so that the distance between the plurality of balance pieces 321 in the circumferential direction is equal, thereby the plurality of The weight of the balance piece 321 may fall on the first end portion 32a of the permanent magnet 32 on average, and is biased toward the outer peripheral surface of the permanent magnet 32 to provide a stable balance effect.

Referring to FIG. 4, it is disclosed that the plurality of balance pieces 321 are respectively provided at the first end portion 32a and the second end portion 32b. In this embodiment, the outer edge 321a is adjacent to the outer circumferential surface of the permanent magnet 32, and a ring flange 323 is disposed on the periphery of the coupling hole 322 to increase the bonding area between the rotating shaft 31 and the permanent magnet 32, and The inner edge 321b is connected to the ring flange 323 of the periphery of the coupling hole 322; in addition, the number of the plurality of balance pieces 321 of the first end portion 32a and the second end portion 32b is four, and the plurality of balance pieces 321 The angle α between each other is also ninety degrees. The distance between the plurality of balance pieces 321 in the circumferential direction is equal; thereby, the weights of the plurality of balance pieces 321 can respectively fall on the first end portion 32a and the second end portion 32b of the permanent magnet 32, respectively. It also provides a stable balance.

Referring to FIG. 5, it is disclosed that the plurality of balance pieces 321 are provided on the first end portion 32a. In this embodiment, the outer edge 321a is adjacent to the outer peripheral surface of the permanent magnet 32, the inner edge 321b is not connected to the coupling hole 322, and the number of the plurality of balance pieces 321 of the first end portion 32a is three. The angles α between the plurality of balance pieces 321 are one hundred and twenty degrees, and the distance between the plurality of balance pieces 321 in the circumferential direction can be equalized to provide a stable balance.

Referring to FIG. 6, it is disclosed that the plurality of balance pieces 321 are disposed on the first end portion 32a of the permanent magnet 32, and the first end portion 32a of the permanent magnet 32 in the axial direction of the rotating shaft 31. There is a first axial height H1 between the second end portions 32b, and the plurality of balance pieces 321 each have a second axial height H2 (when the axial heights of the plurality of balance pieces 321 are different, the The maximum axial height is the second axial height H2), wherein the second axial height H2 may be 0.1 to 0.5 times the first axial height H1. Preferably, the second axial height H2 is The first axial height H1 is 0.15 to 0.4 times; thereby, the plurality of balance pieces 321 can be ensured to provide the stable balance function of the rotor 3, and when the rotor 3 is applied to the motor structure, the rotor can be avoided. 3 occupies too much axial assembly space inside the motor structure.

Referring to FIG. 7, it is disclosed that the plurality of balance pieces 321 are respectively disposed on the first end portion 32a and the first end portion 32b of the permanent magnet 32, and the permanent magnet is in the axial direction of the rotating shaft 31. 32 has a first axial height H1 between the first end portion 32a and the second end portion 32b, and the plurality of balance pieces 321 located at the first end portion 32a each have a second axial height H2 (when the When the axial heights of the plurality of balance pieces 321 are different, the maximum axial height may be defined as the second axial height H2), and the plurality of balance pieces 321 located at the second end portion 32b each have a third axial direction. Height H3 (when the axial heights of the plurality of balance pieces 321 are different, the maximum can be defined The axial height is the third axial height H3), wherein the sum of the second axial height H2 and the third axial height H3 may be 0.1 to 0.5 times the first axial height H1, preferably The sum of the second axial height H2 and the third axial height H3 is 0.15 to 0.4 times the first axial height H1; thereby, the plurality of balance pieces 321 are also ensured to provide the rotor 3 The stable balance function is preferred, and when the rotor 3 is applied to the motor structure, the rotor 3 can be prevented from occupying excessive axial assembly space inside the motor structure.

The present invention is based on the design of the balance piece 321 of the permanent magnet 32. During the rotation of the rotor 2 to drive the rotor 3, a plurality of balance pieces 321 are disposed on at least one end of the permanent magnet 32 of the rotor 3. The distances of the pieces 321 in the circumferential direction are equal to each other, and the weights of the plurality of balance pieces 321 can respectively fall on at least one end portion of the permanent magnet 32, thereby ensuring that the rotor 3 is not easily arbitrarily shifted when rotated. The rotor 3 is provided with a better balanced rotation effect.

Furthermore, when the assembler performs a balance adjustment operation on the rotor 3 by the plurality of balance pieces 321 provided at least at one end portion of the permanent magnet 32 of the rotor 3, the rotor 3 can be rotated due to uneven weight. An unbalanced portion (such as a specific balance piece 321) is partially cut by a machining method to remove a portion of the thickness of the specific balance piece 321 by, for example, mechanical cutting or grinding to remove the corner portion of the balance piece 321 to appropriately reduce the specific portion. The weight of the balance piece 321 is balanced until the rotor 3 can reach the balance of rotation, and therefore, the effects of improving the correction accuracy and the convenience of correction can be achieved.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

1‧‧‧Shell

1a‧‧‧First housing

1b‧‧‧ second housing

11‧‧‧ accommodating space

12‧‧‧ pivotal department

2‧‧‧stator

3‧‧‧Rotor

31‧‧‧Rotary axis

32‧‧‧ permanent magnet

32a‧‧‧First end

32b‧‧‧second end

321‧‧‧ Balance film

321a‧‧‧ outer edge

321b‧‧‧ inside edge

322‧‧‧bond hole

Claims (20)

An inner rotor motor includes: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances The permanent magnet is provided with a first end portion and a second end portion, and the permanent magnet is provided with a coupling hole penetrating the first end portion and the second end portion, and the rotating shaft is coupled to The plurality of balance sheets are respectively disposed on the first end portion and the second end portion. The inner rotor motor according to claim 1, wherein the balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet. The inner rotor motor according to claim 1, wherein the distance between the plurality of balance pieces in the circumferential direction is equal in a radial direction perpendicular to an axial direction of the rotating shaft. The inner rotor motor of claim 1, wherein the plurality of balance pieces each have a pair of outer edges and an inner edge, the inner edge facing the coupling hole, the outer edge facing the outer circumference of the permanent magnet The outer side does not extend beyond the outer peripheral surface of the permanent magnet in a radial direction perpendicular to the axial direction of the rotating shaft. An inner rotor motor includes: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances a piece; wherein the permanent magnet is provided with a first end portion and a second end portion, the permanent magnet The iron is provided with a coupling hole penetrating the first end portion and the second end portion, the rotating shaft is coupled to the coupling hole, and the plurality of balance pieces are disposed at the first end portion, and the plurality of balance pieces each have And an inner side edge facing the coupling hole, the outer edge facing the outer peripheral surface of the permanent magnet, in a radial direction perpendicular to an axial direction of the rotating shaft, the outer edge does not exceed the outer edge The permanent magnet is outside the perimeter. The inner rotor motor according to claim 4, wherein the balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet. The inner rotor motor according to claim 4, wherein the distance between the plurality of balance pieces in the circumferential direction is equal in a radial direction perpendicular to an axial direction of the rotating shaft. The inner rotor motor of claim 4, wherein the outer side edges of the plurality of balance pieces are adjacent to the outer peripheral surface of the permanent magnet. The inner rotor motor according to claim 8, wherein the balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet. The inner rotor motor according to claim 8, wherein the distance between the plurality of balance pieces in the circumferential direction is equal in a radial direction perpendicular to an axial direction of the rotating shaft. The inner rotor motor of claim 4, wherein the peripheral edge of the coupling hole of the permanent magnet is provided with a ring flange, and the outer edge of the plurality of balance pieces is adjacent to the outer peripheral surface of the permanent magnet. The inner edge is connected to the ring flange. The inner rotor motor according to claim 11, wherein the balance piece is made of a magnetic material and integrally formed at an end of the permanent magnet. The inner rotor motor according to claim 11, wherein the distance between the plurality of balance pieces in the circumferential direction is equal in a radial direction perpendicular to an axial direction of the rotating shaft. An inner rotor motor includes: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet rotatably coupled to the pivoting portion of the housing, the permanent magnet being coupled to the rotation The shaft has an air gap between the permanent magnet and the stator, and at least one end of the permanent magnet is provided with a plurality of balance sheets; wherein the balance sheet is made of a magnetic material and integrally formed at an end of the permanent magnet. The inner rotor motor of claim 14, wherein the permanent magnet is provided with a first end portion and a second end portion, the permanent magnet being provided through the first end portion and the second end portion a coupling hole of the end portion, the rotating shaft is coupled to the coupling hole, and the plurality of balance pieces are disposed at the first end portion. An inner rotor motor includes: a housing having at least one pivoting portion; and a stator coupled to the inside of the housing; a rotor including a rotating shaft and a permanent magnet The rotating shaft is rotatably coupled to the pivoting portion of the housing, the permanent magnet is coupled to the rotating shaft, the permanent magnet has an air gap between the stator, and at least one end of the permanent magnet is provided with a plurality of balances a sheet; wherein, in a radial direction perpendicular to an axial direction of the rotation axis, the distance between the plurality of balance pieces in the circumferential direction is equal. The inner rotor motor of claim 16, wherein the permanent magnet is provided with a first end portion and a second end portion, the permanent magnet being provided through the first end portion and the second end portion a coupling hole of the end portion, the rotating shaft is coupled to the coupling hole, and the plurality of balance pieces are disposed at the first end portion. An inner rotor motor comprising: a housing, the housing is provided with at least one pivoting portion; and a stator, the stator is coupled to the inside of the housing; a rotor comprising a rotating shaft and a permanent magnet rotatably coupled to the pivoting portion of the housing, the permanent magnet being coupled to the rotating shaft, the permanent magnet having an air gap between the stator and the stator And at least one end of the permanent magnet is provided with a plurality of balance pieces; wherein the permanent magnet is provided with a first end portion and a second end portion, and the permanent magnet is provided through the first end portion and the first portion a coupling hole of the two ends, the rotating shaft is coupled to the coupling hole, the plurality of balance pieces are disposed at the first end, and the first end of the permanent magnet is in the axial direction of the rotating shaft The second end portion has a first axial height, and the plurality of balance pieces each have a second axial height, and the second axial height is 0.1 to 0.5 times the first axial height. The inner rotor motor of claim 1, wherein the first axial portion to the second end portion of the permanent magnet have a first axial height in the axial direction of the rotating shaft. The plurality of balance pieces of the first end portion each have a second axial height, and the plurality of balance pieces at the second end each have a third axial height, the second axial height and the first The sum of the three axial heights is 0.1 to 0.5 times the first axial height. The inner rotor motor of claim 1, wherein the first axial portion to the second end portion of the permanent magnet have a first axial height in the axial direction of the rotating shaft. The plurality of balance pieces of the first end portion each have a second axial height, and the plurality of balance pieces at the second end each have a third axial height, the second axial height and the first The sum of the three axial heights is 0.15 to 0.4 times the first axial height.