TWI662193B - Structure for holding a fan iron shell to a bearing and fan using same - Google Patents

Abstract

A fan iron casing and a shaft center fixing structure and a fan thereof include a fan wheel and a shaft center. The fan wheel has an iron casing, a hub and a plurality of fan blades. The iron casing has a top portion and an axial direction from its peripheral edge. A side wall is extended, and a hole is formed at the center of the top. The inside of the hole is provided with at least one groove or at least one convex portion. The shaft center has a first end and a second end, and the first end has at least one The combination part is formed on the outer side of the first end, and is embedded with the corresponding groove or convex part. Through the design of this creation, the production cost can be greatly reduced and the assembly is more convenient.

Description

Fan iron shell and shaft fixing structure and fan

This creation relates to a fan iron casing and a shaft fixing structure and a fan thereof, and more particularly to a fan iron casing and a shaft fixing structure and a fan thereof that can greatly reduce production costs and assembly complexity.

Pressing, as the computing performance of electronic devices is increasing, the internal electronic components will generate a large amount of heat during operation. Usually, heat sinks or fins need to be installed on the electronic components to increase the heat dissipation area and improve the heat dissipation effect. The radiator and fins are radiated by radiation to achieve limited heat dissipation effects. Therefore, an additional cooling fan with enhanced cooling efficiency is required to cool the heat sink or fins to improve the cooling performance. Therefore, the cooling fan becomes It is a very important component in the cooling module.

The fan iron casing and the shaft fixing structure are known, as shown in FIG. 1. The shaft 11 is formed on the hole 121 of the copper sleeve 12 by stamping, and the copper sleeve combined with the shaft 11 is continued. 12 A stamping method is used to form a hub 10 on a sleeve hole 131 of an iron shell 13. The hub 10 is molded with a plurality of blades 14 on the outer peripheral side by plastic injection, so that the blades 14 and the hub 10 are formed. Combined to form the fan wheel 1, although the structure of stamping and combining can effectively improve the problem of the skew of the shaft 11 and the deformation of the fan wheel 1 due to the high temperature, another problem is extended, that is, the iron shell 13 needs to pass through the continuous The mold manufacturing process makes the overall fan iron casing and shaft fixing process more tedious and complicated; in addition, through this process, it is necessary to have a copper sleeve 12 to combine the iron casing 13 and the shaft 11, resulting in an increase in the overall cost and an increase in material costs The problem.

As mentioned above, the knowledge has the following disadvantages: 1. Assembly is tedious and complicated; 2. Increase production costs.

Therefore, how to solve the above-mentioned problems and shortcomings is the creators of this case and the relevant manufacturers in this industry who are eager to study the improvement direction.

Therefore, in order to effectively solve the above problems, the main purpose of this creation is to provide a fan iron casing and a shaft fixing structure that can greatly reduce production costs.

The secondary purpose of this creation is to provide a fan iron casing and a shaft fixing structure that can facilitate assembly.

The secondary purpose of this creation is to provide a fan iron shell and shaft fixing structure that can increase the coupling force between the iron shell and the shaft.

The secondary purpose of this creation is to provide a fan that can significantly reduce production costs.

The secondary purpose of this creation is to provide a fan that makes assembly easier.

The secondary purpose of this creation is to provide a fan that can increase the coupling force between the iron shell and the axis.

In order to achieve the above purpose, the present invention provides a fan iron casing and a shaft fixing structure, which includes a fan wheel and a shaft center. The fan wheel has an iron casing, a hub and a plurality of blades. The iron casing has a top. The peripheral edge of the top part extends a side wall axially, a hole is formed at the center of the top part, and at least one groove or at least one convex part is provided on the inner side of the hole, and the hub is covered on the outer peripheral side of the iron shell. An equal fan blade ring is arranged on the outer peripheral side of the hub, the shaft center has a first end and a second end opposite to the first end, the first end has at least one combination part, and the combination part is formed On the outside of the first end, it is embedded with the corresponding groove or protrusion.

Therefore, through the design of this structure, the groove or convex part provided inside the hole is embedded with the combination part of the first end of the shaft center, so that the shaft center and the iron shell can be fixedly combined with each other. Structure, eliminating the need to use copper sleeves to reduce production costs; in addition, the iron shell directly communicates with The shaft center is embedded by contact, which makes assembly easier, and because the shaft center and the iron shell are directly fitted, the coupling force between the shaft center and the iron shell can be greatly improved.

This creation also provides a fan, which includes a frame body, a fan wheel, and a shaft center. The frame body has an accommodation space and a shaft seat. The shaft seat is arranged at the center of the accommodation space, and the shaft seat. It has a shaft hole, and the fan wheel system is pivoted with the shaft seat. The fan wheel has an iron shell, a hub, and a plurality of fan blades. The iron shell has a top portion, and the peripheral edge of the top portion extends axially with a side wall. A hole is formed at the center of the top portion, and at least one groove or at least one convex portion is provided on the inner side of the hole. The hub is covered on the outer peripheral side of the iron shell, and the fan blades are ringed on the hub. On the outer peripheral side, the shaft center has a first end and a second end opposite to the first end, the second end is pivotally disposed in the shaft hole, and the first end has at least one combination part. The combination part is formed on the outer side of the first end, and is embedded in the corresponding groove or convex part.

Therefore, through the design of this structure, the groove or convex part provided inside the hole is embedded with the combination part of the first end of the shaft center, so that the shaft center and the iron shell can be fixedly combined with each other. The structure eliminates the need to use copper sleeves to reduce production costs. In addition, the iron shell is directly in contact with the shaft center and is embedded to achieve more convenient assembly. The shell is directly fitted, so the coupling force between the shaft center and the iron shell can be greatly improved.

2‧‧‧ fan wheel

21‧‧‧Iron case

211‧‧‧Top

2111‧‧‧ Hole

2112‧‧‧Groove

2113‧‧‧Second junction

2114‧‧‧ raised

2115‧‧‧ Fourth junction

212‧‧‧ sidewall

22‧‧‧ Fan Leaf

23‧‧‧ Wheel

3‧‧‧ axis

31‧‧‧ the first end

311‧‧‧Combination Department

311a‧‧‧first joint

311b‧‧‧Third junction

32‧‧‧ the second end

321‧‧‧Groove

4‧‧‧frame

41‧‧‧accommodation space

42‧‧‧Shaft

421‧‧‧shaft hole

5‧‧‧ stator set

51‧‧‧ silicon steel sheet

52‧‧‧coil

Figure 1 is a cross-sectional view of a conventional fan iron casing and shaft fixing structure; Figure 2A is a three-dimensional exploded view of the first embodiment of the fan iron casing and shaft fixing structure; and Figure 2B is a creative fan A three-dimensional combined view of the first embodiment of the iron casing and the shaft fixing structure; FIG. 2C is a cross-sectional view of the first embodiment of the iron casing of the fan and the shaft fixing structure; FIG. 3A is a drawing of the iron casing and the shaft of the fan 3D exploded view of the second embodiment of the core fixing structure; FIG. 3B is a three-dimensional combined view of the second embodiment of the creative fan iron case and the shaft fixing structure; FIG. 3C is of the creative fan iron case and the shaft fixing Sectional view of the second embodiment of the structure; Figure 4A is an exploded perspective view of the third embodiment of the iron fan case and the shaft fixing structure of the creative fan; Figure 4B is a perspective combined view of the third embodiment of the iron fan case and the shaft fixing structure of the creative fan; 4C The figure is a cross-sectional view of the third embodiment of the iron fan case and the shaft fixing structure of the creative fan; FIG. 5A is an exploded perspective view of the fourth embodiment of the iron fan case and the shaft fixing structure of the creative fan; FIG. 5B is the present invention A three-dimensional combined view of the fourth embodiment of the creative fan iron case and the shaft fixing structure; FIG. 5C is a sectional view of the fourth embodiment of the creative fan iron case and the shaft fixing structure; FIG. 6 is the first of the creative fan. An exploded perspective view of the embodiment; FIG. 7 is an exploded perspective view of the second embodiment of the creative fan; FIG. 8 is an exploded perspective view of the third embodiment of the creative fan; Three-dimensional exploded view of the fourth embodiment.

The above-mentioned purpose of this creation and its structural and functional characteristics will be explained according to the preferred embodiments of the drawings.

Please refer to FIGS. 2A, 2B, and 2C, which are an exploded perspective view, a perspective combination view, and a cross-sectional view of the first embodiment of the first embodiment of the fan iron casing and the shaft fixing structure. As shown in the figure, a fan iron casing and the shaft The fixed structure includes a fan wheel 2 and an axis 3, and the fan wheel 2 has an iron casing 21, a hub 23, and a plurality of blades 22. The iron casing 21 has a top portion 211, and a periphery of the top portion 211 A side wall 212 is axially extended, and a hole 2111 is formed at the center of the top portion 211. At least one groove 2112 is provided inside the hole 2111. The hub 23 is covered on the outer peripheral side of the iron casing 21. The 22-series ring is provided on the outer peripheral side of the hub 23, that is, the hub 23 is integrated with the iron shell 21 by means of overmolding, and the outer peripheral side of the hub 23 is formed through plastic injection. The fan blade 22 further forms the fan wheel 2; the aforementioned shaft center 3 has a first end 31 and a second end 32 opposite to the first end 31, and the first end 31 has at least one combination portion 311. The combining portion 311 is formed on the outer side of the first end 31, and Corresponding to the corresponding groove 2112 or the protruding portion 2114, the second end 32 is provided with at least one groove 321, which is formed by being recessed along the outside of the second end 32.

Continuing, please refer to FIG. 2C. Through the creation of the design of this structure, in this embodiment, the combination portion 311 is a convex body, and the convex system is formed by protruding from the outside of the first end 31. The groove 2112 is formed by recessing the inside of the hole 2111 and is embedded with the corresponding convex body. The convex body protruding from the first end 31 is embedded in the groove 2112 inside the hole 2111 to form The structure in which the iron shell 21 and the shaft core 3 are combined and fixed, eliminating the need to use a copper sleeve component when the fan iron shell is combined with the shaft core, which greatly reduces the production cost. In addition, because the iron shell 21 It is directly fitted with the shaft center 3 to achieve a more convenient assembly, and the coupling force between the shaft center 3 and the iron shell 21 can be greatly improved.

Please refer to FIGS. 3A, 3B, and 3C, which are an exploded perspective view, an assembled perspective view, and a cross-sectional view of the second embodiment of the fan iron case and the shaft fixing structure of the original creation. The fan iron case and the shaft fixing structure are described. The corresponding relationship between the components and the components is the same as the above-mentioned fan iron case and the shaft fixing structure, so it will not be repeated here, but the main difference between the fan iron case and the shaft fixing structure and the foregoing is the aforementioned combination The portion 311 is a recessed hole formed from the outside of the first end 31. At least one protruding portion 2114 is provided inside the hole 2111, and the protruding portion 2114 is provided from the inside of the hole 2111. It is convexly formed toward the center of the hole 2111, and is embedded with the corresponding recessed hole. The recessed hole recessed outside the first end 31 is embedded in the protruding portion 2114 protruding inside the hole 2111 to form iron. The structure in which the shell 21 and the shaft 3 are combined and fixed with each other greatly reduces production costs and facilitates assembly, and because the iron shell 21 is directly in contact with the shaft 3 to be fitted and fitted, the shaft is increased to increase the shaft The bonding force between 3 and the iron shell 21.

Please refer to Figs. 4A, 4B, and 4C, which are an exploded perspective view, a three-dimensional combined view, and a cross-sectional view of the third embodiment of the creative fan iron case and the shaft fixing structure. The fan iron case and the shaft fixing structure are described. The corresponding components and the corresponding relationship between the components are the same as the aforementioned fan iron casing and the shaft fixing structure, so it will not be repeated here, but the main difference between the fan iron casing and the shaft fixing structure and the foregoing is as follows: The first end 31 has a plurality of combining portions 311. Each of the foregoing combining portions 311 is a convex body, and the convex systems are along the first The outer side of the end 31 is convexly formed, and the convex bodies define a first joint portion 311a with each other. The grooves 2112 are concavely formed along the inside of the hole 2111, and are correspondingly embedded in the convex bodies. And the grooves 2112 define a second joint portion 2113 with each other, the second joint portion 2113 is fitted with the opposite first joint portion 311a, and the convex body and the groove 2112 are engaged with each other. After being combined and fitted with the first joint portion 311a and the second joint portion 2113, the iron shell 21 and the shaft center 3 can be combined and fixed to each other without passing through a copper sleeve, thereby greatly reducing production costs and assembling more. For the sake of convenience, in addition, since the iron shell 21 is directly fitted and fitted in contact with the shaft core 3, the coupling force between the shaft core 3 and the iron shell 21 is improved.

Please refer to Figs. 5A, 5B, and 5C, which are an exploded perspective view, a combined perspective view, and a cross-sectional view of the fourth embodiment of the fan iron case and the shaft fixing structure of the original creation. The fan iron case and the shaft fixing structure are described. The corresponding components and the corresponding relationship between the components are the same as the aforementioned fan iron casing and the shaft fixing structure, so it will not be repeated here, but the main difference between the fan iron casing and the shaft fixing structure and the foregoing is as follows: The first end 31 has a plurality of combining portions 311. Each of the foregoing combining portions 311 is a recessed hole, and the recessed holes are recessed along the outside of the first end 31, and the recessed holes define a first Three joint portions 311b, the convex portions 2114 are convexly formed along the inside of the hole 2111 toward the center of the hole 2111, and are correspondingly embedded in the concave holes, and the convex portions 2114 are defined between each other A fourth coupling portion 2115 is fitted to the third coupling portion 311b correspondingly, and the convex portion 2114 and the recessed hole are fitted to each other, and the third coupling portion 311b and After the fourth joint portion 2115 is fitted to each other, the iron shell 21 and the shaft center 3 do not need to pass through. The sleeves can also be combined and fixed with each other, so that the production cost is greatly reduced and the assembly is more convenient. In addition, because the iron shell 21 is directly in contact with the shaft 3 and fitted, the shaft 3 and the iron shell are improved. The binding force between 21.

Please refer to FIG. 6, which is an exploded perspective view of the first embodiment of the creative fan. As shown in the figure, a fan includes a frame 4, a fan wheel 2 and an axis 3. The frame 4 It has an accommodating space 41 and a shaft seat 42. The shaft seat 42 is arranged at the center of the accommodating space 41. The shaft seat 42 has a shaft hole 421. The fan wheel 2 is pivoted with the shaft seat 42. It is assumed that the fan wheel 2 has an iron shell 21 and a hub 23 and a plurality of fans. Leaf 22, the iron shell 21 has a top portion 211, and the peripheral edge of the top portion 211 axially extends a side wall 212. A hole 2111 is formed at the center of the top portion 211, and at least one groove 2112 is provided inside the hole 2111. The hub The 23 series is wrapped on the outer peripheral side of the iron casing 21, and the fan blades 22 are ringed on the outer peripheral side of the hub 23, that is, the hub 23 is integrated with the iron casing 21 by means of overmolding, The outer peripheral side of the hub 23 is formed through the injection of the plastic blades 22 to form the fan wheel 2. The shaft center 3 has a first end 31 and a first end 31 opposite to the first end 31. Two ends 32, the second end 32 is pivotally disposed in the shaft hole 421, the first end 31 has at least one combination portion 311, and the combination portion 311 is formed on the outer side of the first end 31, and Correspondingly, the groove 2112 or the protruding portion 2114 is embedded, and the second end 32 of the shaft center 3 is provided with at least one groove 321, and the groove 321 is concavely formed along the outer side of the second end 32.

The aforementioned shaft seat 42 is further provided with a certain sub-group 5. The stator group 5 is composed of a plurality of silicon steel sheets 51 and is wound with a plurality of coils 52.

Please refer to FIG. 6 and FIG. 2C together. Through the creation of the design of this structure, in this embodiment, the combination portion 311 is a convex body, and the convex system is from the outside of the first end 31. The groove 2112 is concavely formed from the inside of the hole 2111 and is embedded with the corresponding convex body. The convex body and the groove 2112 are embedded with each other to form the iron shell 21 and the shaft. The cores 3 are combined and fixed with each other, which eliminates the need to use copper sleeve components when the fan wheel 2 hub is combined with the shaft 3 to reduce production costs. In addition, the iron shell 21 is directly connected to the shaft 3 The contact-fitting arrangement is more convenient for assembly, and the coupling force between the shaft center 3 and the iron shell 21 can be greatly improved.

Please refer to FIG. 7 and FIG. 3C together, which are three-dimensional exploded views of the second embodiment of the creative fan. The components of the fan and the corresponding relationships between the components are the same as the aforementioned fan, so I will not repeat them here, but the main difference between this fan and the foregoing is that the aforementioned combination portion 311 is a recessed hole, which is recessed from the outside of the first end 31, and the inside of the hole 2111 is provided. There is at least one convex portion 2114, and the convex portion 2114 is convexly formed from the inside of the hole 2111 toward the center of the hole 2111, and is embedded with the corresponding concave hole, and passes through the concave hole and the convex portion 2114. Embedded with each other to form the iron shell 21 and the shaft The cores 3 are combined and fixed with each other, eliminating the need to use copper sleeve components when the fan wheel 2 hub is combined with the shaft 3, which greatly reduces the production cost; in addition, the iron shell 21 directly contacts the shaft 3 The fitting arrangement is more convenient for assembly, and the coupling force between the shaft center 3 and the iron shell 21 can be greatly improved.

Please refer to FIG. 8 and FIG. 4C together, which are three-dimensional exploded views of the third embodiment of the creative fan. The components of the fan and the corresponding relationships between the components are the same as those of the aforementioned fan, so I will not repeat it here, but the main difference between this fan and the foregoing is that the first end 31 has a plurality of combining portions 311, and each of the foregoing combining portions 311 is a convex body, and the convex systems are along the first end. 31 is convexly formed on the outer side, and the convex bodies define a first joint portion 311a with each other, the grooves 2112 are concavely formed along the inside of the hole 2111, and are correspondingly embedded in the convex bodies, and The concave bodies define a second joint portion 2113 with each other, and the second joint portion 2113 is fitted with the opposite first joint portion 311a, and the convex body and the groove 2112 are fitted with each other. And after the first joint portion 311a and the second joint portion 2113 are fitted with each other, the iron shell 21 and the shaft center 3 can be fixed to each other without passing through a copper sleeve, so as to reduce production costs and facilitate assembly. In addition, Since the iron shell 21 is directly in contact with the shaft center 3 and is fitted and fitted, the shaft center is improved The bonding force between 3 and the iron shell 21.

Finally, please refer to FIG. 9 and FIG. 5C together, which are three-dimensional exploded views of the fourth embodiment of the creative fan. The components of the fan and the corresponding relationships between the components are the same as those of the aforementioned fan. Therefore, I will not repeat them here, but the main difference between this fan and the foregoing is that the first end 31 has a plurality of combining portions 311, and each of the foregoing combining portions 311 is a recessed hole, and the recessed holes are along the The first end 31 is concavely formed on the outer side, and the concave holes define a third joint portion 311b with each other. The convex portions 2114 are convexly formed along the inside of the hole 2111 toward the center of the hole 2111. Corresponding to the recessed holes, and the convex portions 2114 define a fourth joint portion 2115 with each other, the fourth joint portion 2115 is correspondingly fitted into the third joint portion 311b, and After the convex portion 2114 is fitted with the concave hole, and the third joint portion 311b and the fourth joint portion 2115 are fitted with each other, the iron casing 21 can be made without the need for a conventional copper sleeve. It is fixed to the shaft center 3 to reduce production cost and facilitate assembly. In addition, because the iron shell 21 is directly in contact with the shaft center 3 and fitted, the binding force between the shaft center 3 and the iron shell 21 is improved. .

As mentioned above, this creation has the following advantages compared to the conventional one: 1. The production cost is greatly reduced; 2. The assembly is more convenient; 3. The bonding force between the iron shell and the axis is greatly increased.

The creation has been described in detail above, but the above is only a preferred embodiment of the creation, and the scope of implementation of the creation cannot be limited. That is to say, all equal changes and modifications made in accordance with the scope of this creative application shall still be covered by the patent of this creative.

Claims (13)

A fan iron casing and a shaft fixing structure include: a fan wheel having an iron casing, a hub, and a plurality of blades. The iron casing has a top portion, the peripheral edge of the top portion extends axially with a side wall, and a central portion of the top portion A hole is formed, and at least one groove or at least one protruding portion is provided on the inner side of the hole, the hub is covered on the outer peripheral side of the iron shell, and the fan blade rings are provided on the outer peripheral side of the hub; And a shaft center having a first end and a second end opposite to the first end, the first end having at least one combination part formed on the outer side of the first end, and Correspondingly, the grooves or convex portions are embedded, so that the iron shell is directly in contact with the shaft center and is fitted to improve the coupling force between the shaft center and the iron shell and enhance the structural strength. According to the fan iron casing and the shaft fixing structure described in the first item of the patent application scope, wherein the combination part is a convex body, the convex system is formed by protruding from the outer side of the first end, and the groove is from The inside of the hole is formed concavely, and is embedded with the corresponding convex body. According to the fan iron casing and the shaft fixing structure described in the first item of the patent application scope, wherein the combined portion is a recessed hole, the recessed hole is formed by being recessed from the outside of the first end, and the protruding portion is It protrudes from the inside of the hole toward the center of the hole, and is embedded with the corresponding concave hole. According to the fan iron casing and the shaft fixing structure described in item 1 of the scope of the patent application, wherein the first end has the aforementioned plural combination parts, and each combination part is a convex body, the convex systems follow the The first end is convexly formed on the outer side, and the convex bodies define a first joint portion with each other. The grooves are concavely formed along the inner side of the hole, and are embedded corresponding to the convex bodies, and the concave The grooves define a second joint portion between each other, and the second joint portion is fitted with the first joint portion opposite to the first joint portion. The fan iron casing and the shaft fixing structure according to item 1 of the scope of the patent application, wherein the first end has the aforementioned plural combination parts, each combination part is a recessed hole, and the recessed holes are along the A concave structure is formed on the outer side of the first end, and the concave holes define a third joint portion with each other. The convex portions are convexly formed along the inside of the hole toward the center of the hole, and are embedded corresponding to the The concave hole defines a fourth joint portion between the convex portions, and the fourth joint portion is fitted into the third joint portion correspondingly. The fan iron casing and the shaft center fixing structure according to item 1 of the scope of the patent application, wherein the second end of the shaft center is provided with at least one groove, and the groove is formed concavely along the outer side of the second end. A fan includes: a frame body having an accommodation space and a shaft seat, the shaft seat is arranged at the center of the accommodation space, the shaft seat has a shaft hole, and a fan wheel is connected with the shaft seat The fan wheel has an iron shell, a hub, and a plurality of blades. The iron shell has a top portion, and the peripheral edge of the top portion extends axially from a side wall. A hole is formed at the center of the top portion, and the inside of the hole is provided. There is at least one groove or at least one protruding portion, the hub is covered on the outer peripheral side of the iron shell, and the fan blades are set on the outer peripheral side of the hub; and a shaft center has a first end And a second end opposite to the first end, the second end being pivotally disposed in the shaft hole, the first end having at least one combination part formed on an outer side of the first end, And the corresponding groove or convex portion is embedded, so that the iron shell is directly in contact with the shaft center and fitted to improve the coupling force between the shaft center and the iron shell and enhance the structural strength of the fan. The fan according to item 7 of the scope of patent application, wherein the combination part is a convex body, the convex system is formed by protruding from the outside of the first end, the groove is formed by being recessed from the inside of the hole, and Embedded with the corresponding convex body. The fan according to item 7 of the scope of patent application, wherein the combination portion is a recessed hole, which is recessed from the outside of the first end, and the protruding portion is directed from the inside of the hole toward the hole. The center is convexly formed, and is embedded with the corresponding concave hole. The fan according to item 7 in the scope of the patent application, wherein the first end has the aforementioned plural combination parts, each combination part is a convex body, and the convex systems are convexly extended along the outer side of the first end. And the convex bodies define a first joint portion with each other, the grooves are concavely formed along the inside of the hole, and the corresponding convex bodies are embedded, and the concave bodies define a second The joint portion is fitted with the first joint portion opposite to the joint portion. The fan according to item 7 of the scope of patent application, wherein the first end has the aforementioned plural combination parts, each combination part is a recessed hole, and the recessed holes are recessed along the outer side of the first end And the concave holes define a third joint portion with each other, the convex portions are convexly formed along the inner side of the hole toward the center of the hole, and are embedded corresponding to the concave holes, and the convex portions The setting parts define a fourth joint part with each other, and the fourth joint part is correspondingly fitted with the third joint part. The fan according to item 7 of the scope of patent application, wherein the second end of the shaft center is provided with at least one groove, and the groove is concavely formed along the outer side of the second end. According to the fan described in item 7 of the scope of patent application, the shaft seat is further provided with a certain sub-group, and the stator group is composed of a plurality of silicon steel sheets and is wound with a plurality of coils.