JPH08214476A - Core for small-sized motor - Google Patents

Abstract

PURPOSE: To provide an inexpensive core for small-sized motor which can eliminate the unbalance between magnetic fluxes. CONSTITUTION: A core 1 having a plurality of pole teeth 2, 3, and 4 and a prescribed shape is formed by punching a rolled plate and, at the same time, the surface area of the pole tooth 2 which is formed in the direction which is parallel with or perpendicular to the rolling direction of the rolled plate is made smaller than those of the other pole teeth 3 and 4. It is preferable to set the rate of decrease of the surface area at <=5% when the cogging is taken into account. The surface area of the pole tooth 2 can be reduced by making the width L1 of the rib 1c of the pole tooth 2 narrower than those L2 and L3 of the ribs 1d and 1e of the other teeth 3 and 4, by making the curvature of the corner sections 11i between the rib 11c and tooth section 11f of a pole tooth 12 smaller than those of the corner sections 11j and 11k between the ribs 11d and 11e and teeth sections 11g and 11h of the pole teeth 13 and 14, by narrowing the spreading angle 1 of the tooth section 21f of a pole tooth 22, or by shortening the extending length M1 of the rib 31c of a pole tooth 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor core formed by punching a rolled steel plate so as to have a plurality of radially extending magnetic pole teeth.

[0002]

2. Description of the Related Art Conventionally, in a small motor, a single core having pole teeth composed of a plurality of ribs extending radially from a base portion and teeth portions located at the tips of the plurality of ribs is stamped out from a rolled steel plate. It is known that a rotor is formed by forming a plurality of cores, laminating a plurality of cores, press-fitting a rotating shaft into a base portion, and winding a coil around each magnetic pole tooth.

[0003]

By the way, such a single core is generally formed by punching a rolled steel plate, and the magnetic flux in the rolling direction and the direction orthogonal to the rolling direction of this rolled steel plate is higher than that in the other directions. It is known that it is easy to pass.

However, in the conventional core, since the magnetic pole teeth are located at equal points, stacking the magnetic core teeth as they are results in a magnetically unbalanced core.
At the time of mounting, cogging and torque ripple increase, which causes a problem of low reliability.

Therefore, in order to eliminate such an imbalance of magnetic flux, it is conceivable to use a steel sheet having no magnetic orientation, but in reality, a steel sheet which does not have such magnetic orientation is used. It has been proved that magnetic orientation exists even if it exists.

Therefore, in order to structurally eliminate such an imbalance, it is conceivable to disperse the magnetic directivity by stacking the cores by shifting them at a constant angle (for example, Japanese Patent Publication No. 4-23497). (See issue)
However, in such a case, not only the assembling cost for stacking the individual cores rises, but also the imbalance cannot be completely eliminated due to the relationship between the number of stacked cores and the deviation amount.

In view of the above situation, it is an object of the present invention to provide a small motor core that is inexpensive and can eliminate the imbalance of magnetic flux.

[0008]

In order to achieve the object, the invention described in claim 1 is to form a core having a predetermined shape having a plurality of magnetic pole teeth by punching a rolled steel sheet, and at the same time, in the rolling direction or rolling. The surface area of the magnetic pole teeth in the direction along the perpendicular direction is made smaller than the surface areas of the other magnetic pole teeth.

According to a second aspect of the invention, in the small motor core of the first aspect, the surface area of the magnetic pole teeth in the rolling direction or the direction perpendicular to the rolling direction is made narrower than the surface area of the other magnetic pole teeth. The narrowing rate is set to 5% or less.

In addition, the invention described in claim 3 is the same as claim 1.
Alternatively, in the small motor core described in 2, the surface area is reduced by making the width of the rib of the magnetic pole tooth in the direction along the rolling direction or the direction orthogonal to the rolling narrower than the width of the rib of the other magnetic pole tooth. Furthermore, the invention of claim 4 is the core for a small motor according to claim 1 or 2, wherein the curvature of the corner portion connecting from the rib of the magnetic pole teeth to the tooth portion in the direction along the rolling direction or the direction perpendicular to the rolling is the other magnetic pole. The surface area is reduced by making it smaller than the curvature of the corner connecting the tooth rib to the tooth.

According to a fifth aspect of the present invention, in the small motor core according to the first or second aspect, the spreading angle of the tooth portion of the magnetic pole teeth in the direction along the rolling direction or the direction perpendicular to the rolling is set to be different from that of other magnetic pole teeth. The surface area is narrowed by making it narrower than the spread angle of the teeth. In addition, the invention according to claim 6 is the core for a small motor according to claim 1 or 2, wherein the extension length of the rib of the magnetic pole tooth in the direction along the rolling direction or the direction perpendicular to the rolling is set to the rib of another magnetic pole tooth. The surface area is narrowed by making it shorter than the extension length of.

The core for a small motor of the present invention has a plurality of radially extending magnetic pole teeth, and the surface area of the magnetic pole teeth in the rolling direction or the direction perpendicular to the rolling direction is smaller than the surface area of other magnetic pole teeth. A core having a predetermined shape is formed by punching a rolled steel plate. In the core thus formed, the surface area of the magnetic pole teeth through which the magnetic flux easily passes is smaller than the surface area of the other magnetic pole teeth, so that the magnetic flux imbalance is eliminated. Moreover, since at least one of the magnetic pole teeth extends along the rolling direction or the direction perpendicular to the rolling, and the magnetic pole teeth other than the magnetic pole tooth have a larger surface area, the passage of magnetic flux is maximized. It will be a core that can be used for. In addition, a three-pole core or the like has a line-symmetrical structure centered on magnetic pole teeth through which magnetic flux easily passes, which is easy to manufacture.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a small motor core according to the present invention will be described with reference to FIG.

In FIG. 1A, a core 1 for a small motor includes a base portion 1b having a hole 1a into which a rotary shaft (not shown) is press-fitted, and a rib 1c extending radially from the trisecting position of the base portion 1b. , 1d, 1e and the ribs 1c, 1d,
Teeth portions 1f, 1 formed in a fan shape at the tip of 1e
g, 1h, and the ribs 1c, 1d, 1e and the teeth portions 1f, 1g, 1h form magnetic pole teeth 2, 3, 4 respectively.

The ribs 1c extend (rolling direction in the embodiment) along the rolling direction (arrow X direction) or the direction perpendicular to rolling (arrow Y direction) of the rolled steel sheet. Also, the width L of the rib 1c
1 is set to be narrower than the widths L2 and L3 of the other ribs 1d and 1e, so that the surface area of the magnetic pole teeth 2 through which the magnetic flux easily passes becomes smaller than the surface area of the magnetic pole teeth 3 and 4 through which the magnetic flux does not easily pass. The amount of magnetic flux of each magnetic pole tooth 2, 3, 4 is equal.

In the core 1 having such a structure, the rolled rolled steel plate is punched by a punching die formed so that the ribs 1c are located in the rolling direction and have the above-described shape. Thus, the core 1 in which the surface area of the magnetic pole teeth 2 is smaller than the surface area of the magnetic pole teeth 3 and 4 is formed.

The punched core 1 is laminated into a plurality of layers to form a laminated core. A coil is wound around each magnetic pole tooth 2, 3, 4 and a rotary shaft is press-fitted into the hole 1a to form a rotor.
In order to avoid changing the winding resistance of the coil due to the change of the rib width, the thickness of the insulating treatment of the coil winding portion or the thickness of the insulating material fitted to the rib is changed,
The width of the portion around which the coil is wound is set to be the same for each magnetic pole tooth. Therefore, no special device or work is required for making the coil winding resistances the same. However, if winding resistance is not a problem, it is not necessary to change the thickness of the insulating material or the like.

By the way, the core 1 is, for example, as shown in FIG.
As shown in, among the ribs 11c, 11d, and 11e extending radially from the base portion 11b having the holes 11a, the curvature (R-shaped portion) of the corner portion 11i continuous from the rib 11c along the rolling direction to the tooth portion 11f is set. The surface area of the magnetic pole tooth 12 is made smaller by making the curvature of the corner portion 11j continuous from the other rib 11d to the tooth portion 11g and the curvature of the corner portion 11k continuous from the rib 11e to the tooth portion 11h. The core 11 may be narrower than that.

Further, as shown in FIG. 1C, the hole 21a is formed.
Ribs 21 extending radially from a base portion 21b having
Of the substantially fan-shaped teeth 21f, 21g, and 21h provided at the tips of c, 21d, and 21e, the spread angle θ1 of the teeth 21f formed at the tips of the ribs 21c along the rolling direction is set to the other teeth 21g. , 21h are made narrower than the spread angles θ2 and θ3, so that the surface area of the magnetic pole teeth 22 is made smaller than that of the magnetic pole teeth 23 and 24.
It may be 1.

Further, as shown in FIG.
Of the ribs 31c, 31d, 31e that radially extend from the base portion 31b having a and have substantially fan-shaped teeth portions 31f, 31g, 31h at their tips, the extension length M1 of the rib 31c along the rolling direction is Other ribs 31d and 31e
The core 31 may have a surface area of the magnetic pole teeth 32 smaller than that of the magnetic pole teeth 33 and 34 by making the core length 31 shorter than the extension lengths M2 and M3.

Each of these cores 11, 21, 31 is
Similarly to the core 1 described above, the surface area of the magnetic pole teeth 12, 22, 32 is simultaneously punched out from the rolled steel plate so that the other magnetic pole teeth 13, 22,
It is smaller than the surface area of 14,23,24,33,34.

Further, in the core thus constructed, when the surface area of the magnetic pole teeth in the rolling direction or the direction perpendicular to the rolling direction is made smaller than the surface area of the other magnetic pole teeth to be 5% or less, the result is shown in FIG. Thus, the amount of cogging is reduced, which is preferable. It should be noted that other motor characteristic values, such as torque ripple, are not necessarily within this range, but various motor characteristic values can be improved by reducing the value by several percent.

Further, in each of the above-described embodiments, the core 1 used for the rotor having the three magnetic pole teeth 2, 3 and 4 is disclosed, but the number of magnetic pole teeth is not particularly limited. At this time, when the magnetic pole teeth extend along the rolling direction or the direction perpendicular to the rolling, the cutting die is set so as to be narrower than the surface area of the other magnetic pole teeth in the same manner as in the above-described embodiments. At the same time as punching, cores having different surface areas are formed.
Further, the core according to the present invention is not limited to the rotor core, but can be used for the stator core.

By punching so that the surface area of the magnetic pole teeth in the direction along the rolling direction or the direction perpendicular to the rolling direction is made smaller than the surface area of the other magnetic pole teeth in this way, the core 1 is simply laminated to make it constant. It is possible to configure a laminated core of a well-balanced magnetic flux without shifting for each angle. Particularly, in the three-pole core as shown in FIG. 1, two magnetic pole teeth other than the magnetic pole teeth in the direction along the rolling direction or the direction perpendicular to the rolling are arranged in line symmetry with respect to the rolling direction or the direction perpendicular to the rolling. Therefore, the difficulty of passing the magnetic flux is the same. As a result, the two magnetic pole teeth can have the same shape, resulting in a core with good magnetic balance. This is preferable because it is extremely simple in design in terms of magnetic balance.

[0025]

As described above, in the small motor core according to the first aspect of the present invention, the core of a predetermined shape having a plurality of magnetic pole teeth is formed by punching the rolled steel plate, and the direction of rolling or rolling is performed. By making the surface areas of the magnetic pole teeth in the direction along the right angle smaller than the surface areas of the other magnetic pole teeth, the imbalance of the magnetic flux can be eliminated at low cost. In addition, since the magnetic pole teeth in the rolling direction or the direction perpendicular to the rolling direction are effectively used, the core can maximize the ease of passing the magnetic flux.

Further, in the small motor core according to the second aspect, the cogging amount is reduced, and the small motor using this core can rotate smoothly.

Further, in the core for a small motor according to claims 3 to 6, the width of the rib is changed, the curvature of the corner portion continuous from the rib to the tooth portion is changed, the spread angle of the tooth portion is changed, and the rib is changed. The surface area of the magnetic pole teeth is changed by changing the extension length of the magnetic pole teeth, so that the target core can be formed with a die having a simple structure. Therefore, the manufacturing of the punching die becomes easy, and the cost of manufacturing the core does not increase.

[Brief description of drawings]

FIG. 1 shows a core for a small motor of the present invention, (A) is a front view of the core alone when the width of the rib is narrowed, and (B) is a case where the R portion continuous from the rib to the tooth portion is reduced. FIG. 4C is a front view of the core alone, FIG. 7C is a front view of the core alone when the extending angle of the teeth portion is narrowed, and FIG. 7D is a front view of the core alone when the extension length of the rib is short.

FIG. 2 is a graph showing the relationship between the ratio of the surface area of the magnetic pole teeth in the rolling direction or the direction perpendicular to the rolling direction to the other magnetic pole teeth and the amount of coking.

[Explanation of symbols]

 1 ... Core 2 ... Magnetic pole tooth 3 ... Magnetic pole tooth 4 ... Magnetic pole tooth

Claims (6)

[Claims] 1. A core of a predetermined shape having a plurality of magnetic pole teeth is formed by punching a rolled steel plate, and the surface area of the magnetic pole teeth in the direction along the rolling direction or the direction perpendicular to the rolling is larger than the surface area of other magnetic pole teeth. Small motor core characterized by being narrowed. 2. The surface area of the magnetic pole teeth in the rolling direction or the direction perpendicular to the rolling direction is made smaller than the surface areas of the other magnetic pole teeth, and the narrowing ratio is set to 5% or less. Small motor core. 3. The surface area is reduced by narrowing the width of the rib of the magnetic pole tooth in the rolling direction or the direction perpendicular to the rolling direction to be narrower than the width of the rib of the other magnetic pole tooth. Small motor core. 4. The curvature of the corner connecting the rib of the magnetic pole tooth to the tooth in the rolling direction or the direction orthogonal to the rolling is made smaller than the curvature of the corner connecting the rib of another magnetic pole tooth to the tooth. The core for a small motor according to claim 1 or 2, wherein the surface area is reduced by. 5. A surface area is narrowed by making a spreading angle of a tooth portion of a magnetic pole tooth in a direction along a rolling direction or a direction perpendicular to rolling smaller than a spreading angle of a tooth portion of another magnetic pole tooth. The core for a small motor according to 1 or 2. 6. The surface area is narrowed by making the extension length of the rib of the magnetic pole tooth in the rolling direction or the direction perpendicular to the rolling direction shorter than the extension length of the rib of the other magnetic pole tooth. The core for a small motor according to item 1 or 2.