TWI632761B - Fan, rotor and its permanent magnetic components - Google Patents

Abstract

The invention provides a fan, a rotor and a permanent magnetic component thereof. The permanent magnetic component comprises a body having a plurality of first magnetic pole regions, a plurality of second magnetic pole regions and a plurality of composite magnetic pole regions, each of the first magnetic pole regions and each of the second magnetic pole regions. Adjacent to the body, each of the first magnetic pole regions and each of the second magnetic pole regions are separated by each composite magnetic pole region, and the composite magnetic pole regions have at least one N magnetic pole block and at least one S magnetic pole. Block. The invention can achieve the effect of saving space and reducing weight.

Description

Fan, rotor and its permanent magnetic components

The invention relates to the technical field of a fan, in particular to a fan, a rotor and a permanent magnetic component thereof which have the advantages of achieving space saving and reducing overall weight, and having better sinusoidal magnetic flux.

According to the increasing popularity of personal computers and the booming of the computer industry, the problems of heat generation and heat dissipation of various electronic components are becoming more and more important. Therefore, the use of fans as the main heat dissipation components is currently the trend, and At present, the current computer industry is widely used, only in that its structure is simple and small, and it can quickly solve the problem of heat generation and heat dissipation of electronic components.

Referring to Figures 1, 2A, 2B, and 2C, the centrifugal fan 1 is a combination of a rotor 10 and a stator 11 and a frame 12. The rotor 10 is housed in a frame 12, and the rotor 10 is It is formed by a wheel 101, a rotor yoke 102 (i.e., a motor iron case made of metal), and a permanent magnet 103. The permanent magnet 103 is composed of a plurality of N magnetic poles and a plurality of S magnetic poles which are alternately arranged. The rotor yoke 102 The plurality of blades 1012 are annularly disposed on the outer peripheral side of the hub 1011, and the permanent magnets 103 are received on the inner peripheral side of the rotor yoke 102. And the stator 11 is composed of a stator core 111 formed by laminating steel sheets and a coil group 112 wound around the stator core, and the stator 11 is disposed on a shaft cylinder 121 of the frame body 12, the shaft cylinder 121 and The rotor 10 has a shaft center 105 pivoted. So when the centrifugal fan 1 is running At this time, the permanent magnet 103 of the rotor 10 is inductively excited with the stator 11 to drive the rotor 10 to operate to guide the airflow to generate a heat dissipation effect.

Since the foregoing permanent magnets 103 are generally multi-pole magnetized and need to be mounted on the motor iron shell (ie, the rotor yoke 102), the magnetic flux of the adjacent phase magnetic poles adjacent to the permanent magnets 103 are almost all involved in the magnetic field. In the loop, and in order to make the magnetic circuit of the permanent magnet 103 form a closed loop, the rotor yoke 102 (ie, the motor iron shell) must use a ferromagnetic material (ie, a magnetic conductive material), so that the wear on the rotor can be avoided. . Therefore, the main function of the rotor yoke 102 is to shield the inner ring magnetic circuit of the permanent magnet 103 to form a closed loop (as shown in FIG. 2C), but it extends another problem that the rotor yoke 102 not only increases the weight of the overall rotor 10, Moreover, it also causes a problem of occupying the space in the hub 1011, and thus the air gap magnetic flux density is low and the magnetic flux sinusity is poor.

Accordingly, in order to effectively solve the above problems, it is an object of the present invention to provide a permanent magnetic element of a rotor having the effect of saving space and reducing overall weight.

Another object of the present invention is to provide a permanent magnetic component having a rotor which achieves cost savings and which is capable of improving the air gap flux density and magnetic flux sinus.

Another object of the present invention is to provide a rotor having the effect of achieving space saving and reducing overall weight.

Another object of the present invention is to provide a rotor which is cost effective and which is capable of improving the air gap magnetic flux density and magnetic flux sinus.

Another object of the present invention is to provide a permanent magnetic component that is magnetized in a radial multi-pole, double-loop cross-array, eliminating the need for a rotor of a conventional rotor yoke component.

Another object of the present invention is to provide a permanent magnetic component with a radial multi-pole double-ring cross-array magnetization method, which can use a rotor yoke of a non-magnetic material (such as plastic or aluminum), thereby achieving cost saving and weight reduction. Rotor.

Another object of the present invention is to provide a fan having the effect of saving space and reducing overall weight.

Another object of the present invention is to provide a fan which achieves cost savings and which is capable of improving the air gap flux density and the magnetic flux sinusoidality.

To achieve the above object, the present invention provides a permanent magnetic component of a rotor, comprising a body having a plurality of first magnetic pole regions, a plurality of second magnetic pole regions, and a plurality of composite magnetic pole regions, each of the first magnetic pole regions and each of A second magnetic pole region is disposed adjacent to the body, and each of the two first magnetic pole regions is separated by each of the composite magnetic pole regions, and each of the two second magnetic pole regions is separated by each of the composite magnetic pole regions And the composite magnetic pole region has at least one N magnetic pole block and at least one S magnetic pole block; therefore, the design of the permanent magnetic component of the invention can effectively save product space and reduce product weight, and can also improve The air gap magnetic flux density is higher and the magnetic flux sinusoidal property is better.

The present invention further provides a rotor comprising a fan wheel and at least one permanent magnetic component, the fan wheel comprising a hub and a plurality of blades, the blade rings being disposed on an outer peripheral side of the hub, the hub having a receiving space The permanent magnetic component is disposed in the hub of the receiving space, the permanent magnetic component includes a body having a plurality of first magnetic pole regions, a plurality of second magnetic pole regions, and a plurality of composite magnetic pole regions, each of the first magnetic poles The region is disposed adjacent to each of the second magnetic pole regions on the body, and each of the two first magnetic pole regions is separated by each of the composite magnetic pole regions, and each of the two second magnetic pole regions is separated by each The magnetic pole regions are spaced apart, and the composite magnetic pole regions have at least one N magnetic pole block and at least one S magnetic pole block; The design makes it effective to save product space and reduce product weight, as well as improve air gap flux density and magnetic flux sinusoidality.

The present invention further provides a fan having the rotor of the present invention, thereby achieving the effect of saving product space and reducing product weight, and also improving the air gap magnetic flux density and magnetic flux sinusability.

The present invention further provides a permanent magnetic component of a rotor, comprising a body having a plurality of first magnetic pole regions and a plurality of second magnetic pole regions, wherein the first magnetic pole regions are adjacent to the second magnetic pole regions and are disposed adjacent to the body A portion of each of the first magnetic pole regions is formed with a magnetic pole block different from the first magnetic pole region, and a portion of each of the second magnetic pole regions is formed with a different polarity from the second magnetic pole region. Therefore, through the design of the permanent magnetic component of the present invention, the effect of saving product space and reducing the weight of the product can be effectively achieved, and the air gap density and the magnetic flux sinusability can be improved.

In one implementation, one side of each of the first magnetic pole regions is adjacent to one side of each of the second magnetic pole regions, and the other side of each of the first magnetic pole regions is adjacent to each of the composite magnetic pole regions, The other side of each of the second magnetic pole regions is adjacent to each of the composite magnetic pole regions.

In one implementation, the first magnetic pole regions and the second magnetic pole regions are formed by radial magnetization on the body, and the first magnetic pole regions are N magnetic pole regions or S magnetic pole regions, and the second The magnetic pole region is an S magnetic pole region or an N magnetic pole region.

In one implementation, the N magnetic pole block and the S magnetic pole block of each composite magnetic pole region are formed by radial magnetization on the body, and the N magnetic pole block between the two first magnetic pole regions is The S magnetic pole blocks are respectively disposed on the inner side of the adjacent body and the outer side of the adjacent body, and the N magnetic pole block and the S magnetic pole block between the two second magnetic pole regions are respectively disposed adjacent to the outer side of the body. Adjacent to the inside of the body.

In one implementation, the body is a permanent magnet.

In one implementation, each of the first magnetic pole regions and each of the second magnetic pole regions are arranged side by side in a radial direction, and the N magnetic pole blocks and the S magnetic pole blocks of each composite magnetic pole region are juxtaposed in a radial direction. Adjacent settings.

In one implementation, the body is formed by magnetization of a radially multi-pole, double-loop cross-array.

In one implementation, the non-magnetic material is a plastic material or an aluminum material.

In one implementation, the hub is made of a plastic material, and a rotor yoke is not disposed in the hub, and the permanent magnetic component is directly adhered to the inner side of the hub provided in the receiving space.

In one implementation, the hub is made of a plastic material, and the rotor is provided with a rotor yoke made of a non-magnetic material, the rotor yoke is disposed on the inner side of the hub in the receiving space, and the rotor yoke The iron is located between the body and the hub, and the permanent magnetic element is received and adhered to the inner side of the rotor yoke.

2‧‧‧fan

21‧‧‧Permanent magnetic components

211‧‧‧ body

212‧‧‧First magnetic pole zone

213‧‧‧Second magnetic pole zone

214‧‧‧Composite magnetic pole zone

2141‧‧‧N magnetic pole block

2142‧‧‧S magnetic pole block

22‧‧‧ Stator

23‧‧‧Box

231‧‧‧ accommodating space

232‧‧‧Base

2321‧‧‧Axis hole

234‧‧‧wind side

24‧‧‧ Cover

241‧‧‧wind side

25‧‧‧Rotor

251‧‧‧fan wheel

252‧‧·wheels

2521‧‧‧ Included space

2523‧‧‧ fan leaves

253‧‧‧ rotor yoke

254‧‧‧Axis

Fig. 1 is an exploded perspective view of a conventional centrifugal fan.

Figure 2A is a schematic cross-sectional view of a conventional centrifugal fan.

Figure 2B is a top plan view of a permanent magnet of a conventional centrifugal fan.

Fig. 2C is a schematic view showing the distribution of magnetic lines of the permanent magnet and the rotor yoke of the conventional centrifugal fan.

Figure 3 is a top plan view of a permanent magnetic component of an embodiment of the present invention.

Fig. 3A is a schematic view showing the distribution of magnetic lines of force of the permanent magnetic member of the embodiment of the present invention.

Fig. 4 is a schematic view showing the distribution of magnetic lines of force of another permanent magnetic element of an embodiment of the present invention.

Figure 5 is an exploded perspective view of an embodiment of the present invention.

Figure 6 is a schematic cross-sectional view showing a combination of embodiments of the present invention.

Figure 7 is a graph of the present invention and conventional magnetic flux density and magnetic field strength (B-H).

Figure 8 is a schematic cross-sectional view showing another combination of embodiments of the present invention.

The above object of the present invention, as well as its structural and functional features, will be described in accordance with the preferred embodiments of the drawings.

The invention is a fan, a rotor and its permanent magnetic components. Please refer to FIG. 3, which is a top plan view of an embodiment of the present invention, and is supplemented with reference to FIG. 3A. The permanent magnetic component 21 includes a body 211. The body 211 is formed by a permanent magnet system magnetized by a radial multi-pole double-ring cross array. The body 211 has a plurality of first magnetic pole regions 212 and a plurality of In the second magnetic pole region 213 and the complex magnetic pole region 214, the first magnetic pole region 212 and the second magnetic pole region 213 are respectively denoted as an N magnetic pole region and an S magnetic pole region in the embodiment, but are not limited thereto, and in specific implementation, It is also possible to design each of the first magnetic pole regions 212 to be an S magnetic pole region and each of the second magnetic pole regions 213 to be an N magnetic pole region. And each of the first magnetic pole regions 212 is disposed adjacent to each of the second magnetic pole regions 213 on the body 211 and is formed by radial magnetization, such as each of the foregoing first magnetic pole regions 212 in FIG. Each of the second magnetic pole regions 213 is disposed adjacent to each other in the front-rear direction, and one side of each of the first magnetic pole regions 212 is adjacent to one side of each of the second magnetic pole regions 213, and each of the first magnetic pole regions 212 The other side is adjacent to each of the composite magnetic pole regions 214, and the other side of each of the second magnetic pole regions 213 is adjacent to each of the composite magnetic pole regions 214.

Each of the first first magnetic pole regions 212 is separated by each of the composite magnetic pole regions 214, and each of the two second magnetic pole regions 213 is separated by each of the composite magnetic pole regions 214, and the composite magnetic pole regions 214 have At least one N magnetic pole block 2141 and at least one S magnetic pole block 2142, the N magnetic pole block 2141 and the S magnetic pole block 2142 between each of the two first magnetic pole regions 212 are respectively disposed adjacent to the body in this embodiment. The inner side of the 211 is adjacent to the outer side of the body 211 and is formed by radial magnetization. The N magnetic pole block 2141 and the S magnetic pole area are located between each of the second magnetic pole regions 213. The block 2142 is respectively disposed on the outer side of the main body 211 and adjacent to the inner side of the main body 211 and is formed by radial magnetization, such as the N magnetic pole block 2141 of each composite magnetic pole region 214 in FIG. The S magnetic pole block 2142 is disposed adjacent to each other in the left and right radial direction. One side of the N magnetic pole block 2141 between each of the two first magnetic pole regions 212 is adjacent to the inner peripheral side of the main body 211, and the first two are first. The other side of the N-pole block 2141 between the magnetic pole regions 212 is adjacent to one side of the S-pole block 2142, and the other side of the S-pole block 2142 is adjacent to the outer peripheral side of the body 211, the second and second One side of the S pole block 2142 between the magnetic pole regions 213 is adjacent to the inner peripheral side of the body 211, and the other side of the S magnetic pole block 2141 between the two second magnetic pole regions 213 is adjacent to the N magnetic pole block. On one side of the 2141, the other side of the N magnetic pole block 2141 is adjacent to the outer peripheral side of the body 211.

Therefore, the body 211 of the permanent magnetic component 21 is magnetized by a radial multi-pole double-ring cross array (as shown in FIG. 3), so that the outer loop of the body 211 (ie, the permanent magnet) is shaped like a closed loop of the inner loop. As shown in FIG. 3A, the magnetic lines of force of the body 211 are similar to the magnetic lines of the body 211 in the inner loop of the outer loop, so that the permanent magnetic element 2 of the present invention has a conventional rotor yoke. 102 (as in Figure 2C). Therefore, the design of the permanent magnetic member 21 of the present invention is effective in achieving space saving and weight reduction. In addition, each of the magnetic pole regions of the inner ring of the body 211 (i.e., the N, S magnetic pole blocks 2141, 2142 of each composite magnetic pole region 214) has an inner unique magnetic pole cycle, thereby locking the central portion. The magnetic flux of the magnetic pole (ie, the intermediate position between each of the first and second magnetic pole regions 212, 213) participates in the circulation of the adjacent out-of-phase magnetic pole, so the magnetic flux density at the center of each magnetic pole of the inner ring is higher, the center The higher the magnetic flux density, the better the sinusoidality.

In order to more clearly illustrate the efficacy of the present invention, please refer to FIG. 7 , which is a graph of magnetic flux density and magnetic field strength (BH) according to the present invention. In the figure, curve B1 is represented as the present invention, and curve B2 is represented. As is conventional, it can be seen from Figure 7 that the air gap flux density of the present invention is significantly higher than conventional air gap flux densities. its The vertical axis in Figure 7 represents the air gap flux density B in Tesla (T) and the horizontal axis represents the magnetic field strength H in am/m (A/m).

In one implementation, as shown in FIG. 4, the body 211 is modified to have the first magnetic pole region 212 and the second magnetic pole regions 213, and the composite magnetic pole region 214 between the two first magnetic pole regions 211. The first magnetic pole region 212 adjacent to the two sides is designed to be the same magnetic pole region (ie, the first magnetic pole region 212), and the composite magnetic pole region 214 between each of the two second magnetic pole regions 213 is designed to be adjacent to both sides. The second magnetic pole region 213 is regarded as the same magnetic pole region (ie, the second magnetic pole region 213), and the first magnetic pole regions 212 and the second magnetic pole regions 213 are adjacently disposed on the body 211, and each of the first A portion of a magnetic pole region 212 itself is formed with a magnetic pole block (such as an S magnetic pole block 2142) different from the first magnetic pole region 212 (such as the N magnetic pole region), and each of the second magnetic pole regions 213 itself a portion of the magnetic pole block (ie, the N magnetic pole block 2141) that is different from the second magnetic pole region 213 (such as the S magnetic pole region) is formed on a portion thereof, but is not limited thereto. In another implementation, the first The magnetic pole region 212 may be an S magnetic pole region and a magnetic pole block of a portion thereof is an N magnetic pole block 2141, and the second magnetic pole region 213 may be N Region itself blocks part of the magnetic pole is S pole block 2142. Therefore, through the design of the first and second magnetic pole regions 212 and 213 of the body 211, the magnetic lines of the body 211 are in the outer loop, and the magnetic lines of the body 211 are closed in the inner loop, so that the permanent loop of the present invention The magnetic element 21 has the function as the conventional rotor yoke 102 (as in Figure 2C). Therefore, the effect of saving space, cost, and weight is effectively achieved, and the effect of the air gap flux density and the magnetic flux sinus is also effectively improved.

Please refer to Figures 5 and 6, which are schematic exploded cross-sectional and combined cross-sectional views of a second embodiment of the present invention, supplemented by reference to Figures 3 and 3A. This embodiment mainly applies the permanent magnetic element 21 of the first embodiment described above to a fan 2, which is shown as a centrifugal fan 2 in this embodiment, but is not limited thereto. The fan 2 includes a rotor 25, a stator 22, a cover plate 24 and a frame 23, and the cover plate 24 is covered. The cover body 24 has a wind inlet side 241. The frame body 23 has a receiving space 231 communicating with the air inlet 241 and a base 232 disposed in the center of the receiving space 231. The wind side 234 is disposed on one side of the frame and communicates with the accommodating space 231. The stator 22 is disposed on the pedestal 232. The rotor 25 is received in the accommodating space 231 and covers the corresponding stator. 22, the first and second magnetic pole regions 212, 213 of the body 211 of the permanent magnetic element 21 of the rotor 25 are inductively excited with the opposing stator 22 to operate in the accommodating space 231.

The rotor 25 is shown in the present embodiment as a rotor 25 without a rotor yoke (ie, a rotor 25 without a motor casing). The rotor 25 includes a fan wheel 251 and at least one permanent magnetic element 21, the fan wheel 251 having a The hub 252 and the plurality of blades 2523 are disposed on the outer peripheral side of the hub 252. The hub 252 is formed of a plastic material. The hub 252 has a shaft center 254 and a receiving space 2521. One end of the shaft 254 is fixed at the center of the hub 252 in the receiving space 2521. The other end of the shaft 254 is pivoted with a shaft hole 2321 opposite to the base 232, and a rotor yoke is not disposed in the hub 252 (eg Motor iron shell). The structure and the connection relationship of the permanent magnetic element 21 of the present embodiment and the effect thereof are the same as those of the permanent magnetic element 21 of the first embodiment, and therefore will not be described again herein, and the permanent magnetic element 21 is directly used in this embodiment. The adhesive element is in contact with the inner side of the hub 252 in the receiving space 2521. However, in a specific implementation, the permanent magnetic element 21 can also be designed to be integrally molded with the hub 252 such that the inner side of the hub 252 integrally covers the permanent magnetic element 21.

Therefore, the permanent magnetic component 21 of the present invention is applied to the fan 2, so that no additional conventional rotor yoke 102 (such as FIG. 2C) components are required in the rotor 25, thereby effectively saving space, saving cost, and reducing overall weight. It is also effective to achieve an increase in the air gap flux density and the magnetic flux sinusoidality. In one embodiment, as shown in Fig. 8, and referring to Fig. 5, a rotor yoke 253 (i.e., a motor casing made of a non-magnetic material) made of a non-magnetic material is disposed in the hub 252 of the rotor 25 of the fan 2. The non-magnetic material is a plastic material or an aluminum material, and the rotor yoke 253 is disposed on the inner side of the hub 252 disposed in the receiving space 2521. The rotor yoke is located at the body 211 and the hub. between. The body 211 of the permanent magnetic component 21 is received and adhered to the inner side of the rotor yoke 253. Therefore, the permanent magnetic component 21 of the present invention is applied to the fan 2, so that the rotor 25 can be made of a non-magnetic material, thereby effectively achieving cost saving and overall weight reduction, and effectively improving the air gap flux density. And the magnetic flux sinusoidal is better.

Claims (15)

A permanent magnetic component of a rotor includes a body having a plurality of first magnetic pole regions, a plurality of second magnetic pole regions, and a plurality of composite magnetic pole regions, each of the first magnetic pole regions being disposed adjacent to each of the second magnetic pole regions Each of the two first magnetic pole regions is separated by each of the composite magnetic pole regions, and each of the second magnetic pole regions is separated by each of the composite magnetic pole regions, and each of the first magnetic pole regions One side is adjacent to one side of each of the second magnetic pole regions, and the other side of each of the first magnetic pole regions is adjacent to each of the composite magnetic pole regions, and the other side of each of the second magnetic pole regions Each of the composite magnetic pole regions is adjacent, and the composite magnetic pole regions have at least one N magnetic pole block and at least one S magnetic pole block. The permanent magnetic component of the rotor of claim 1, wherein the first magnetic pole region and the second magnetic pole region are formed by radial magnetization on the body, and the first magnetic pole regions are The N magnetic pole region or the S magnetic pole region is an S magnetic pole region or an N magnetic pole region, and the first magnetic pole regions are different from the second magnetic pole regions. The permanent magnetic component of the rotor of claim 1, wherein the N magnetic pole block and the S magnetic pole block of each composite magnetic pole region are formed on the body by radial magnetization, and each The N magnetic pole block and the S magnetic pole block of the composite magnetic pole region between the two first magnetic pole regions are respectively disposed on an inner side adjacent to the main body and adjacent to the outer side of the main body, between the two second magnetic pole regions The N magnetic pole block and the S magnetic pole block of the composite magnetic pole region are respectively disposed adjacent to the outside of the body and adjacent to the inner side of the body. The permanent magnetic component of the rotor of claim 1, wherein the body is a permanent magnet. The permanent magnetic component of the rotor of claim 1, wherein each of the first magnetic pole regions and each of the second magnetic pole regions are disposed adjacent to each other in a radial direction, the N of each composite magnetic pole region. The magnetic pole block and the S magnetic pole block are arranged adjacent to each other in the left and right radial direction. The permanent magnetic component of the rotor of claim 1, wherein the body is formed by magnetization of a radially multipole double loop cross array. A rotor comprising: a wheel comprising a hub and a plurality of blades, wherein the blade ring is disposed on an outer peripheral side of the hub, the hub has a receiving space; at least one permanent magnetic component is disposed in the casing In the hub of the space, the permanent magnetic component comprises a body having a plurality of first magnetic pole regions, a plurality of second magnetic pole regions and a plurality of composite magnetic pole regions, each of the first magnetic pole regions and each of the second magnetic pole regions Adjacently disposed on the body, each of the two first magnetic pole regions is separated by each of the composite magnetic pole regions, and each of the two second magnetic pole regions is separated by each of the composite magnetic pole regions, each of the first One side of one magnetic pole region is adjacent to one side of each of the second magnetic pole regions, and the other side of each of the first magnetic pole regions is adjacent to each of the composite magnetic pole regions, and each of the second magnetic pole regions is another One side is adjacent to each of the composite magnetic pole regions, and the composite magnetic pole regions have at least one N magnetic pole block and at least one S magnetic pole block. The rotor of claim 7, wherein the first magnetic pole region and the second magnetic pole regions are formed by radial magnetization on the body, and the first magnetic pole regions are N magnetic pole regions. Or S magnetic pole regions, the second magnetic pole regions are S magnetic pole regions or N magnetic pole regions, and the first magnetic pole regions are different from the second magnetic pole regions. The rotor of claim 7, wherein the N magnetic pole block and the S magnetic pole block of each composite magnetic pole region are formed on the body by radial magnetization, and the second magnetic poles are respectively The N magnetic pole block and the S magnetic pole block of the composite magnetic pole region between the regions are respectively disposed on the inner side of the adjacent body and the outer side of the adjacent body, and the composite magnetic pole between each of the second magnetic pole regions The N magnetic pole blocks of the region are respectively disposed on the outer side of the adjacent body and adjacent to the inner side of the body. The rotor of claim 7, wherein the body is a permanent magnet. The rotor of claim 7, wherein the hub is made of a plastic material, and a rotor yoke is not disposed in the hub, and the permanent magnetic component is directly adhered to the inner side of the hub of the receiving space. . The rotor of claim 7, wherein the hub is made of a plastic material, and the rotor is provided with a rotor yoke made of a non-magnetic material, and the rotor yoke is disposed in the receiving space. On the inner side of the hub, and the rotor yoke is located between the body and the hub, the permanent magnetic element is received and adhered to the inner side of the rotor yoke. The rotor of claim 12, wherein the non-magnetic material is a plastic material or an aluminum material. A fan having the rotor according to any one of claims 7 to 13 of the patent application. A permanent magnetic component of a rotor includes a body having a plurality of first magnetic pole regions and a plurality of second magnetic pole regions, the first magnetic pole regions being adjacently disposed adjacent to the second magnetic pole regions on the body, each of the plurality a magnetic pole block different from the first magnetic pole region is formed on a portion of the first magnetic pole region, and a magnetic pole region different from the second magnetic pole region is formed on a portion of each of the second magnetic pole regions Piece.