JP5707831B2 - Powder core and method for producing the same - Google Patents

Description

  The present invention relates to a dust core and a method for producing the same.

  In recent years, a dust core has attracted attention as an iron core material for electric devices such as motors. The powder core is manufactured by press-molding and heat-treating a mixture in which an iron-based magnetic powder is coated with an insulator and, if necessary, a binder is added. Therefore, it is possible to produce an iron core having a three-dimensional structure, unlike an electromagnetic steel sheet that has been widely used as an iron core material for electric devices such as motors. Thus, the width of the structural design of electrical equipment has been greatly expanded by the dust core.

JP 2008-278623 A JP 2008-135560 A

  However, there are some disadvantages in using a dust core as an iron core. For example, a dust core has a problem that it is difficult to obtain a high-density product because it is produced by pressure-molding an iron-based magnetic powder coated with a coating. When the density is low, the magnetic flux density of the dust core is low, and as a result, it is difficult to obtain a high-performance electric device.

  In addition, the shape of an electromagnetically optimized iron core is often complicated, but it is not easy to produce a dust core having a complicated shape by pressure molding. In particular, when the mold has a complicated shape, the press pressure cannot be increased, or pressure molding is performed by a mold lubrication method in which a lubricant is applied to the inner surface of the mold and the magnetic powder is not mixed with the lubricant. It is even more difficult to obtain a high-density product because it is difficult.

Although it is possible to actually increase the pressing pressure or to produce a dust core using the mold lubrication method, in such cases, troubles such as the inability to remove the molded product from the mold occur frequently. In addition, the mold life is significantly reduced. Therefore, the above-described method is not suitable for mass production of complex-shaped dust cores. Therefore, when producing a dust core having a complicated shape by a method suitable for mass production, it is difficult to obtain a dust core having a high density and a high magnetic flux density.
Accordingly, an object of the present invention is to solve the above-described problems of the prior art and provide a compact powder core having excellent magnetic properties and a method for manufacturing the same.

In order to solve the above problems, the present invention has the following configuration. That is, the method for producing a dust core according to the present invention is a method for producing a dust core having a shape in which one or more protrusions protrude from the main body portion by press-molding a raw material powder containing magnetic powder. In the first molding step, the component raw material powder is filled in a component molding die and press-molded with a predetermined press pressure to produce one or more types of components, and obtained in the first molding step. One or more of each of the various parts is placed in a mold for forming a dust core, the part forms the protrusion , one end of the part is embedded in the main body portion, and the radial outer diameter of the part The side part is covered with the main body part, or only the radially inner diameter side part and the axial front end surface of the surface of the component are exposed from the main body part, and the other parts are covered with the main body part. as the configurations, the powder of the component (A) The powder core is obtained by placing the powder at the predetermined position in the molding die and filling the powder for molding the main body into the powder core molding die and press-molding with a predetermined press pressure. Each of the press pressures when molding the various parts in the first molding step is higher than the press pressure when molding the dust core in the second molding step. It is characterized by high pressure.

In such a method for manufacturing a dust core according to the present invention, it is preferable to include a heat treatment step of heat-treating the dust core obtained in the second molding step.
Further, when molding at least one of the various components in the first molding step, the component molding die having an inner surface coated with a lubricant is used, and the dust core is formed in the second molding step. At the time of molding, it is preferable to use the raw material powder for a main body part containing a lubricant.

Furthermore, the component raw material powder and the main body part raw material powder contain a binder, and the content of the binder contained in the component raw material powder used when molding at least one of the various components is: It is preferable that the content of the binder contained in the main body portion raw material powder is smaller.
Furthermore, the concentration of impurities contained in the component raw material powder used when molding at least one of the various components is lower than the concentration of impurities contained in the main body portion raw material powder and less than 1000 ppm. It is preferable.

Furthermore, it is preferable that the component raw material powder used when molding at least one of the various components is flattened.
Furthermore, it is preferable that the average particle size of the main body portion raw material powder is smaller than the average particle size of the component raw material powder. In that case, it is more preferable that the average particle size of the raw material powder for main body part is 50 μm or more and 100 μm or less, and the average particle size of the raw material powder for parts is 200 μm or more and 300 μm or less.
Furthermore, the dust core according to the present invention is a dust core obtained by press-molding a raw material powder containing magnetic powder, and having a shape in which one or more protrusions protrude from the main body portion, It is manufactured by the manufacturing method of the dust core which concerns on this invention like this.

The iron core of the motor, which is the main application of the dust core, is composed of yokes, teeth, etc. Of these, it is often the teeth, that is, the protrusions, that most easily saturate the magnetic flux during operation. . That is, it is a projection part among powdered cores that require high density. In addition, since each of the teeth of the iron core of the motor rarely has a complicated shape, it is easy to press-mold the teeth in advance at a high pressure.
Therefore, if a compact corresponding to the protrusion (tooth) is prepared by press molding at high pressure in advance, the compact is placed in a mold, further filled with magnetic powder and press-molded. It is possible to obtain a powder core having a high and difficult to saturate protrusion.

  According to the method for producing a dust core according to the present invention, a dust core having a complicated shape having excellent magnetic properties can be produced. In addition, the dust core according to the present invention has excellent magnetic properties despite its complex shape.

It is a perspective view explaining the structure of the electromagnetic unit of 1st embodiment. It is a disassembled perspective view of the electromagnetic unit of FIG. FIG. 2 is a cross-sectional view of a stator core (a dust core) incorporated in the electromagnetic unit of FIG. 1. It is sectional drawing which shows the modification of the stator core (compact core) of FIG. It is a fragmentary top view which shows another modification of the stator core (compact core) of FIG. It is a perspective view which shows the structure of the electromagnetic unit of 2nd embodiment. It is a disassembled perspective view of the electromagnetic unit of FIG. It is a perspective view which shows the structure of the electromagnetic unit of 3rd embodiment. It is a disassembled perspective view of the electromagnetic unit of FIG. It is a perspective view which shows the structure of the electromagnetic unit of 4th embodiment. It is a disassembled perspective view of the electromagnetic unit of FIG. It is a perspective view which shows the structure of the motor of 5th embodiment. It is a perspective view which shows the structure of the motor of 6th embodiment. FIG. 5 is a schematic diagram for explaining a state in which particles of both raw material powders in a joint portion between a stator yoke and a tooth are engaged when the average particle diameters of the component raw material powder and the main body part raw material powder are the same. It is a schematic diagram explaining the state of meshing of the particles of both raw material powders at the joint portion of the stator yoke and the teeth when the average particle diameters of the raw material powder for parts and the raw material powder for main part are different.

Embodiments of a dust core and a method for producing the same according to the present invention will be described in detail with reference to the drawings.
[First embodiment]
1 is a perspective view for explaining the structure of an electromagnetic unit (element constituting a motor) using a dust core according to the present invention as an iron core, and FIG. 2 is an exploded perspective view of the electromagnetic unit of FIG. . In FIG. 1, only a part of the teeth included in the rotor and the stator is omitted so that the detailed structure of the electromagnetic unit can be easily seen.

First, the structure of the electromagnetic unit shown in FIGS. The electromagnetic unit shown in FIGS. 1 and 2 is an element constituting an axial motor suitable for downsizing (thinning). The electromagnetic unit is arranged substantially concentrically with the rotor 10 and the rotor 10 via a gap. And a substantially annular stator 20 facing each other.
The stator 20 is concentric along a stator core 23 formed of an annular stator yoke 21 and a plurality of teeth 22 and along an inner diameter surface of the stator core 23 (specifically, along a row of a plurality of teeth 22 arranged as will be described later). And an annular coil 25 arranged in proximity to each other. The number of turns of the coil 25 is not particularly limited, and may be set as appropriate according to the supplied voltage.

  The stator core 23 will be described in detail (see also FIG. 3, which is a cross-sectional view of the stator core 23 cut along a plane along the axial direction), and a plurality of teeth 22 are provided to protrude in the axial direction from one axial end surface of the stator yoke 21. These teeth 22 are arranged along the circumferential direction at predetermined intervals. And this stator core 23 is comprised with the powder core obtained by press-molding the raw material powder containing a magnetic powder. The stator yoke 21 corresponds to a main body portion that is a constituent element of the present invention, and the tooth 22 corresponds to a protrusion that is a constituent element of the present invention.

  On the other hand, the rotor 10 includes an annular rotor yoke 11 and a plurality of teeth 12 (the same number as the teeth 22 of the stator 20). More specifically, a plurality of teeth 12 are formed to project radially outward from the outer diameter surface of the rotor yoke 11, and these teeth 12 are arranged along the circumferential direction with a predetermined interval therebetween. Since these teeth 12 are made of a magnetic material such as iron or a dust core, for example, protrusions and recesses made of a magnetic material are alternately arranged in the circumferential direction on the outer diameter surface of the rotor yoke 11. It becomes.

  Each tooth 12 of the rotor 10 can be opposed to each tooth 22 of the stator 20 via a gap. More specifically, the axial front end surface of each tooth 22 of the stator 20 and the axial side surface of each tooth 12 of the rotor 10 can be opposed to each other via an axial gap (see FIG. 1). Note that the number of teeth 12 of the rotor 10 and the number of teeth 22 of the stator 20 are not necessarily the same. Even if the number is not the same, if the magnetic energy changes as described later according to the rotation of the rotor 10, rotational torque is generated.

  Instead of providing the teeth 12 made of a magnetic material such as iron or a dust core on the outer diameter surface of the rotor yoke 11, a plurality of magnetic poles (for example, permanent magnets) are provided along the circumferential direction on the outer diameter surface of the rotor yoke 11. May be arranged. In this case, the surface of the outer surface of the magnetic pole that faces the teeth 22 of the stator 20 is an N-pole or S-pole, and the opposite surface is a magnetic pole that is an N-pole and a magnetic pole that is an S-pole along the circumferential direction. Place them alternately. The number of teeth 22 of the stator 20 and the number of magnetic pole pairs (N-pole and S-pole pairs) of the rotor 10 is preferably the same.

  When the teeth 12 of the rotor 10 and the teeth 22 of the stator 20 are opposed to each other (facing state), the magnetic body including both the teeth 12 and 22 surrounds the conduction direction of the coil 25. The magnetic path of the magnetic flux generated by 25 is formed. This state is the most magnetically stable (low magnetic energy) state as the rotational position of the rotor 10, so that no rotational torque is generated even if a current is supplied to the coil 25.

  On the other hand, when each tooth 12 of the rotor 10 and each tooth 22 of the stator 20 are not opposed to each other (non-facing state), a large space exists in the magnetic path surrounding the conduction direction of the coil 25. . And since the magnetic resistance of a magnetic path becomes large compared with the said facing state, the magnetic flux which generate | occur | produces when an electric current is supplied to the coil 25 becomes smaller than the said facing state. Since this state is the most magnetically unstable (high magnetic energy) state as the rotational position of the rotor 10, even if current is supplied to the coil 25, theoretically no rotational torque is generated.

  Actually, when the rotational position of the rotor 10 slightly deviates from the facing state or the unfacing state, rotational torque is generated in a direction in which the magnetic energy decreases. For example, if the teeth 12 of the rotor 10 and the teeth 22 of the stator 20 are shifted by a quarter of the distance between the teeth (hereinafter also referred to as a pitch), a current is supplied to the coil 25. When supplied, magnetic flux is generated, and rotational torque is generated in a direction in which each tooth 12 of the rotor 10 and each tooth 22 of the stator 20 are in the above-described facing state. In other words, since the directly facing state is the most magnetically stable (low magnetic energy) state, a rotational torque is generated to reach that state.

Therefore, when an electric current is supplied to the coil 25 of the stator 20 of the electromagnetic unit, an axial magnetic flux is generated in each tooth 22 of the stator 20, and the rotor 10 rotates about the shaft by the mechanism described above. The rotation of the rotor 10 is transmitted to a member (not shown) connected to the rotor 10.
This electromagnetic unit uses a dust core with excellent magnetic properties and an optimized complex three-dimensional shape as an iron core. Compared to the case where an electromagnetic steel sheet is used as an iron core, this electromagnetic unit is It has the advantages described above. And such an electromagnetic unit is suitable as an element which comprises the motor integrated in an electric equipment, an electronic device, an industrial machine, a motor vehicle, a robot, etc.

  Since it is only necessary to fit the coil 25 into the inner diameter surface of the stator core 23, the assembly of the stator 20 is extremely easy, and furthermore, the rotor 10 and the stator 20 can be fitted together from the side surface. The assembly of the electromagnetic unit is also good. Further, although the support mechanism for the rotor 10 and the stator 20 is not shown in the drawing, it may be held so as to be relatively rotatable while maintaining the positions in the axial direction and the radial direction.

Next, the manufacturing method of the powder core which comprises the stator core 23 is demonstrated. This powder core is manufactured by press-molding a raw material powder containing magnetic powder. And this pressure molding consists of the following two-stage pressure molding processes.
First, a part (for example, a columnar part as shown in FIGS. 1 and 2) for forming the teeth 22 of the stator 20 is manufactured by the first molding step. In that case, the component raw material powder is filled in a component molding die and press-molded with a predetermined pressing pressure. One type of component may be used, but a plurality of types of components having different shapes, types of component raw material powders, molding conditions, and the like may be manufactured as desired.

  Next, a stator core 23 in which a plurality of teeth 22 protrude in the axial direction from one axial end surface of the stator yoke 21 is manufactured by a second molding step. In that case, the said components are put in the metal mold | die for powder core shaping | molding, and the said components are arrange | positioned in the predetermined position in the metal mold | die for powder core shaping | molding so that the said parts may form the teeth 22. FIG. Then, when the main body part raw material powder is filled into the compacting core molding die and press-molded with a predetermined pressing pressure, a stator yoke 21 is formed from the main body part raw material powder, and a stator including teeth 22 is formed. A stator core 23 composed of the yoke 21 is obtained. At this time, the press pressure at the time of molding the component in the first molding step is higher than the press pressure in the second molding step.

  In addition, when using multiple types of components, each of the various components may be used one by one, or a plurality of components may be used. Further, the stator yoke 21 and the teeth 22 may be in contact with each other as shown in FIG. 3, but as shown in FIG. 4 (a cross-sectional view of the stator core 23 cut along a plane along the axial direction). One end of the component may be embedded in the main body portion (stator yoke 21), and the radially outer diameter side portion of the component may be covered with the stator yoke 21. Further, as shown in FIG. 5 (a plan view of the teeth 22 of the stator core 23 seen from the axial direction), only the radially inner diameter side portion and the axial front end surface of the surface of the component are exposed from the stator yoke 21. These portions may be covered with the stator yoke 21.

  The component raw material powder and the main body part raw material powder are preferably soft magnetic powders coated with an insulating film. The component of the powder is not particularly limited as long as it exhibits soft magnetism, and examples thereof include pure Fe, Fe-Si alloy, permalloy, etc., but it is used at a low frequency like a motor core and has a high magnetic flux density. Is required, pure Fe is preferably used. This powder is preferably produced by, for example, a water atomization method, and its particle size is preferably several tens to several hundreds μm (for example, 100 μm). The powder is preferably a flat powder obtained by subjecting a granular powder to flattening (for example, a method of flattening mechanically by a dry method).

  Furthermore, the raw material powder for parts and the raw material powder for main part may be the same type of powder or different types of powder. For example, when improving the magnetic properties of a dust core by using a powder with high purity (low concentration of impurities such as oxygen), the raw material powder for parts of the raw material powder for parts and the raw material powder for main part Only high purity (less than 1000 ppm) should be used. By doing so, it is possible to minimize the cost increase in improving the magnetic characteristics. The lower the impurity concentration, the better the performance, but if it is lower than normal (1000 ppm), the magnetic properties of the dust core can be improved. In the case where a plurality of types of component powders are produced using a plurality of types of component raw material powders, the magnetic properties can be improved if at least one of the component raw material powders has a high purity. .

  Furthermore, for the purpose of removing distortion generated during pressure molding, the stator core 23 obtained by the second molding step may be appropriately heat-treated. When heat treatment is performed, it is preferable to form an insulating film with a material having high heat resistance on the component raw material powder and the main body part raw material powder. Examples of such a material having high heat resistance include phosphate compounds and magnesium oxide (MgO) as well known.

  Furthermore, the raw material powder for parts and the raw material powder for main body part may contain a binder. The type of binder is not particularly limited, and examples thereof include polyimide, epoxy resin, phenol resin, and silicone resin. Moreover, 1.0 mass% or less of the whole raw material powder is preferable, and, as for content of a binder, 0.5 mass% or less is more preferable. When the content of the binder is large, the nonmagnetic portion inside the molded body increases and the magnetic characteristics may be insufficient.

  Furthermore, when both the raw material powder for parts and the raw material powder for main part contain a binder, the raw material powder for parts preferably contains less binder than the raw material powder for main part. By doing so, it is possible to increase the density of only the portion where the magnetic flux is easily saturated without significantly reducing the strength. In the case of producing a plurality of types of parts using a plurality of types of component raw material powders, if the content of at least one of the component raw material powders is less than the content of the main body part raw material powder, the above effect is obtained. Is obtained.

Below, it demonstrates still in detail about said 1st shaping | molding process and 2nd shaping | molding process.
The parts corresponding to the teeth 22 are manufactured from the raw material powders for parts as described above, but not only one type of parts, but also multiple types of parts having different shapes, types of raw material powders for parts, molding conditions, etc. are manufactured. These may be used not only for the tooth part but also for any part. Since the teeth 22 often do not have a very complicated shape, the parts can be manufactured by high pressure compression molding and can be pressure molded at a higher pressure than the pressure molding in the second molding step. When producing a plurality of types of parts, all types of parts are pressure-molded at a higher pressure than the pressure molding in the second molding step.

  The pressure of pressure molding in the first molding step is not particularly limited, but is preferably 700 MPa or more and 1200 MPa or less, and more preferably 800 MPa or more and 1000 MPa or less. If the pressing pressure is too low, the density of the formed body will not be sufficiently high, and there is a possibility that a high magnetic flux density in the tooth portion, which is the effectiveness of the present invention, cannot be realized. On the other hand, if the pressing pressure is too high, mass production becomes difficult from the viewpoint of reducing the life of a part molding die even with a simple shape.

  The shape of the component molding die at this time may be determined as appropriate in accordance with the designed structure of the tooth 22, but from the viewpoint of improving the strength of the dust core, it is preferable to devise the following. That is, the length of the part is made longer than the teeth 22 of the stator core 23. By doing so, a part of the part is embedded in the main body part (stator yoke 21) in the second molding step (see FIG. 4), and simply rides on the main body part (stator yoke 21). The strength of the dust core is improved as compared with the state (see FIG. 3).

Further, when the flat powder is pressure-molded, the flat surface of the flat powder tends to be arranged with the flat surface perpendicular to the pressing direction. Therefore, when flat powder is used, the pressing direction of pressure molding is determined so that the flat surface of the flat powder arranged by pressure molding is aligned with the direction of magnetic flux flow of the finished powder core. Good.
Furthermore, it is preferable to use a lubricant when pressure forming the part. In that case, the lubricant may be mixed with the raw material powder for parts. However, in order to obtain a high-density molded body, the lubricant is applied to the inner surface of the mold for molding the part to obtain the raw material powder for parts. It is preferable to use a mold lubrication method in which a lubricant is not mixed. Although the kind of lubricant to be used is not particularly limited, for example, a stearic acid-based lubricant can be mentioned.

The part obtained by pressure molding under the above conditions is preferably used as it is for the production of the powder core in the second molding step. By doing so, the curing of the binder does not proceed, so that the familiarity between the component and the raw material powder for the main body portion becomes good. However, the parts may be heat-treated before being subjected to pressure molding in the second molding step.
Next, a powder core is produced using one or more kinds of parts thus obtained and the raw material powder for the main body portion. Since the parts corresponding to the teeth 22 have already been pressure-molded, the volume thereof hardly changes even if the parts are pressed again in the second molding step. Therefore, it is necessary to appropriately determine the initial position of each punch in consideration of this. For example, in the case of the dust core as shown in FIG. 3, the punch may be one stage, but in the case of the dust core as shown in FIG. 4, the punch needs to be three stages.

  Moreover, it is preferable to mix a lubricant with the main body part raw material powder. The mold lubrication method can be used in the same manner as in the case of pressure molding of parts. However, when pressure molding is performed with a complex-shaped mold, it is better to mix the lubricant with the raw material powder for the body part. The frequency of troubles, such as being unable to come out of the mold, can be reduced. 1.0 mass% or less is preferable, and, as for the mixing amount of the lubricant with respect to the whole raw material powder for main body parts, 0.1 mass% or more and 0.5 mass% or less are more preferable.

  In the second molding step, the parts are first arranged at a predetermined position in the compacting core molding die, and thereafter, an appropriate amount of raw material powder for the main body portion is filled in the gaps between the parts. At this time, if the size of the portion corresponding to the teeth 22 in the dust core molding die is larger than that of each component, and a gap is generated between the component and the dust core molding die, The position of the part within the powder core mold must be determined.

  In general, the highest magnetic flux density required in the teeth 22 is often a part of the outer surface of the teeth 22, so that the surface of the part is used as a dust core molding die. What is necessary is just to fix components in the state contacted to the inner surface (so that the surface of the components is exposed from the dust core). For example, such fixing can be performed by applying resin or the like to the parts.

  In addition, when the surface where the highest magnetic flux density is required is the tip end surface in the axial direction of the tooth 22, for example, the longitudinal end surface of the columnar component is in contact with the inner surface of the mold for forming a dust core. After fixing, the raw material powder for the main body part may be filled in the mold for forming the powder core. However, it is not always necessary for the teeth portion to have a part of the part exposed, and the part may be fixed so that the part is not exposed at all by filling a small amount of powder.

  When the components are arranged in the powder core molding die and filled with the raw material powder for the main body portion as described above, pressure molding is performed. The press pressure at the time of pressure molding in the second molding step is preferably 500 MPa or more and 1000 MPa or less, and more preferably 600 MPa or more and 800 MPa or less. In the case of a dust core with a complicated shape, if the pressure molding is performed at a high pressure, the molded product may not come out of the dust core molding die, or the life of the dust core molding die may be significantly reduced. It is preferable not to mold at a high press pressure. In particular, since the density of the teeth part can be made relatively high by making it smaller than the press pressure at the time of molding the part, high mass productivity and high magnetic flux density of the teeth part can be realized simultaneously. Can do.

  The molded body thus obtained is heat-treated at a temperature of 300 ° C. or higher and 600 ° C. or lower, thereby removing the distortion caused by the pressure molding and reducing the core loss (when the binder is contained, the binder is also cured at the same time). Let the powder core complete. Since the optimum value of the heat treatment temperature varies depending on the type of the insulating film of the raw material powder, it may be appropriately determined according to the substance constituting the insulating film. The heat treatment time is preferably 10 minutes or more and 1 hour or less, and the atmosphere may be selected from air, nitrogen and the like. As described above, a dust core having excellent magnetic properties despite the complicated shape can be produced.

[Second Embodiment]
The structure of the electromagnetic unit of the second embodiment will be described in detail with reference to FIGS. FIG. 6 is a perspective view illustrating the structure of the electromagnetic unit according to the second embodiment, and FIG. 7 is an exploded perspective view of the electromagnetic unit of FIG. However, since the configuration and operational effects of the electromagnetic unit of the second embodiment are substantially the same as those of the first embodiment, only different parts will be described and description of the same parts will be omitted. 6 and 7, the same or corresponding parts as those in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS.

  In the rotor 10 of the electromagnetic unit according to the second embodiment, a plurality of teeth 12 are formed to protrude radially outward from the outer diameter surface of the rotor yoke 11, but the protrusion length of the teeth 12 is compared with the first embodiment. Therefore, the teeth 12 are arranged on the radially inner side of the teeth 22 of the stator 20. The radially inner side surfaces of the teeth 22 of the stator 20 and the radial front end surfaces of the teeth 12 of the rotor 10 can be opposed to each other via a radial gap (see FIG. 6).

  Since such an electromagnetic unit can be shortened in the axial direction, it can be further downsized (thinned). In general, since the cylindrical surface can be processed with higher accuracy than the flat surface, the facing surface of each tooth 22 of the stator 20 facing the teeth 12 of the rotor 10 is more radial than the front end surface in the axial direction. The inner side is preferred. When the opposing surface is a radially inner side surface, the distance between the opposing surfaces (the size of the gap) can be shortened, and hence the magnetic resistance viewed from the coil 25 can be reduced, so that the generated magnetic flux It increases and it becomes easy to increase torque.

[Third embodiment]
The structure of the electromagnetic unit according to the third embodiment will be described in detail with reference to FIGS. FIG. 8 is a perspective view for explaining the structure of the electromagnetic unit of the third embodiment, and FIG. 9 is an exploded perspective view of the electromagnetic unit of FIG. However, since the configuration and operational effects of the electromagnetic unit of the third embodiment are substantially the same as those of the first and second embodiments, only different parts will be described, and description of the same parts will be omitted. 8 and 9, the same or corresponding parts as those in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS.

  In the rotor 10 of the electromagnetic unit of the third embodiment, a plurality of teeth 12 protrude from the outer diameter surface of the rotor yoke 11 toward the stator 20 side in the axial direction. Since the rotor yoke 11 has a larger diameter than the stator yoke 21, the teeth 12 of the rotor 10 are arranged on the radially outer side of the teeth 22 of the stator 20. The radially outer side surface and the radially inner side surface of each tooth 12 of the rotor 10 can be opposed to each other via a radial clearance (see FIG. 8).

  In general, since the cylindrical surface can perform machining with higher accuracy than the flat surface, the opposing surface of each tooth 22 of the stator 20 that opposes each tooth 12 of the rotor 10 is radially outer than the front end surface in the axial direction. Sides are preferred. When the opposing surface is a radially outer side surface, the distance between the opposing surfaces (the size of the gap) can be shortened, and thus the magnetic resistance viewed from the coil 25 can be reduced, so that the generated magnetic flux It increases and it becomes easy to increase torque.

[Fourth embodiment]
The structure of the electromagnetic unit according to the fourth embodiment will be described in detail with reference to FIGS. FIG. 10 is a perspective view for explaining the structure of the electromagnetic unit of the fourth embodiment, and FIG. 11 is an exploded perspective view of the electromagnetic unit of FIG. However, since the configuration and operational effects of the electromagnetic unit of the fourth embodiment are substantially the same as those of the first to third embodiments, only different parts will be described, and description of the same parts will be omitted. 10 and 11, the same reference numerals as those in FIGS. 1 and 2 are given to the same or corresponding parts as those in FIGS.

  In the rotor 10 of the electromagnetic unit of the fourth embodiment, a plurality of teeth 12 are formed so as to protrude from the axial end surface of the rotor yoke 11 toward the stator 20 side in the axial direction. On the other hand, in the stator 20, a plurality of teeth 12 are formed so as to protrude from the axial end surface of the stator yoke 21 toward the rotor 10 side in the axial direction. Two rows are formed concentrically with a gap in the radial direction.

  The teeth 12 of the rotor 10 are disposed in the radial gap, and the radially outer side surface of each tooth 22 of the inner diameter side teeth row of the stator 20 and the radially inner side surface of each tooth 12 of the rotor 10 are respectively It is possible to face each other through a radial gap, and the radial inner side surface of each tooth 22 of the outer diameter side teeth row of the stator 20 and the radial outer side surface of each tooth 12 of the rotor 10 are respectively in the radial gap. (See FIGS. 10 and 11).

  Such an electromagnetic unit can generate a rotational torque for each of the two tooth rows, so that a large torque can be achieved. In general, since the cylindrical surface can be processed with higher accuracy than the flat surface, the facing surface of each tooth 22 of the stator 20 facing the teeth 12 of the rotor 10 is more radial than the front end surface in the axial direction. Sides are preferred. When the opposing surface is a radial side surface, the distance between the opposing surfaces (the size of the gap) can be shortened, and thus the magnetic resistance viewed from the coil 25 can be reduced, so that the generated magnetic flux increases. However, it becomes easy to increase torque. The number of teeth rows of the stator 20 can be three or more. In that case, it is preferable to appropriately increase the number of teeth rows of the rotor 10 according to the number of teeth rows of the stator 20.

[Fifth embodiment]
The structure of the motor of the fifth embodiment will be described in detail with reference to FIG. FIG. 12 is a perspective view illustrating the structure of the motor of the fifth embodiment. However, since the configuration and operational effects of the electromagnetic unit that is an element constituting the motor of the fifth embodiment are substantially the same as those of the first to fourth embodiments, only different portions will be described, and descriptions of the same portions will be omitted. To do. In FIG. 12, the same or corresponding parts as those in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS.

  The electromagnetic units of the first to fourth embodiments can generate rotational torque according to the rotational positions of the teeth 12 of the rotor 10 and the teeth 22 of the stator 20, and reverse the polarity of the current supplied to the coil 25. As a result, the polarity of the rotational torque can be reversed. However, when the rotor 10 of the electromagnetic unit has a tooth 12 made of a magnetic material such as iron or a dust core and does not have a magnetic pole, the rotational torque generated by one electromagnetic unit is a pulsating torque. A torque that continuously rotates in one direction cannot be generated. Therefore, in order to continuously generate rotational torque in one direction to function as a motor, it is necessary to configure the motor using three or more electromagnetic units.

  The motor of FIG. 12 is configured by connecting three electromagnetic units U1, U2, U3 of the second embodiment in the axial direction. Each electromagnetic unit U1, U2, U3 is connected with the stator 20 oriented in the same axial direction (in FIG. 12, the stator 20 faces downward). However, the number of electromagnetic units to be connected is not limited to three and may be four or more. Although not shown, the three rotors 10 and the three stators 20 are mechanically connected to each other, and are relatively rotatably held. That is, a structure in which three rotors 10 are connected functions as a motor rotor, and a structure in which three stators 20 are connected functions as a motor stator.

  In each of the electromagnetic units U1, U2, and U3 constituting the motor, the rotational positions of the teeth 12 of the rotor 10 and the teeth 22 of the stator 20 do not coincide with each other (is not in a directly-facing state). The amount of deviation gradually increases from the electromagnetic unit at one end in the axial direction toward the electromagnetic unit at the other end, and the increase in the amount of deviation is constant.

  However, with respect to the electromagnetic unit at one axial end, the rotational positions of the teeth 12 and 22 may coincide. For example, in the case of the motor shown in FIG. 12, in the electromagnetic unit U1 at the lower end, the rotational positions of the teeth 12 and 22 coincide with each other, and the central electromagnetic unit U2 is shifted by 1/3 pitch. In the electromagnetic unit U3, it is shifted by 2/3 pitch (the shift amount is increased by 1/3 pitch).

  In the case of the motor of FIG. 12, the rotational positions of the teeth 12 of the rotor 10 of the three electromagnetic units U1, U2, and U3 are all aligned, and the rotational positions of the teeth 22 of the stator 20 are not aligned. Since the relative positional relationship only needs to be shifted, the configuration is such that the rotational positions of the teeth 22 of the stator 20 are aligned and the rotational positions of the teeth 12 of the rotor 10 are not aligned, contrary to FIG. Good.

  When a predetermined current is supplied to each of the coils 25 of the three electromagnetic units U1, U2, and U3, the respective electromagnetic units U1, U2, and U3 generate rotational torque. Since the rotors 10 and the stators 20 of the three electromagnetic units U1, U2, and U3 are mechanically connected to form the rotor and stator of the motor, the rotational torque generated in the motor rotor is three electromagnetics. This is the total (synthetic torque) of the rotational torques of the units U1, U2 and U3. Since this combined torque has a waveform in which pulsation is superimposed on a constant rotational torque, continuous rotational torque can be generated.

[Sixth embodiment]
The structure of the motor of the sixth embodiment will be described in detail with reference to FIG. FIG. 13 is a perspective view illustrating the structure of the motor of the sixth embodiment. However, the configuration and operational effects of the electromagnetic unit, which is an element constituting the motor of the sixth embodiment, are almost the same as those of the first to fourth embodiments, so only the different parts will be described and the description of the same parts will be omitted. To do. In FIG. 13, the same reference numerals as those in FIGS. 1 and 2 are assigned to the same or corresponding parts as those in FIGS.

  Unlike the motor of the fifth embodiment, when the rotor 10 of the electromagnetic unit has the magnetic pole 31, the motor can be configured using two electromagnetic units. As shown in FIG. 13, a thin motor can be obtained by connecting the stators 20 of the two electromagnetic units U1 and U2 to each other on the back. That is, the other end surface in the axial direction of the stator yoke 21 (the end surface in the axial direction where the teeth 22 are not formed) are opposed to each other, and the stators 20 of both electromagnetic units U1 and U2 are connected to each other to constitute a motor.

Although not shown, the two rotors 10 and the two stators 20 are mechanically connected to each other, and are relatively rotatably held. That is, a structure in which two rotors 10 are connected functions as a motor rotor, and a structure in which two stators 20 are connected functions as a motor stator.
In at least one of the electromagnetic units U1 and U2 constituting the motor, the rotational positions of the magnetic pole 31 of the rotor 10 and the teeth 22 of the stator 20 do not match (not in a directly-facing state) and are shifted. And the difference of the deviation | shift amount of both electromagnetic units U1 and U2 is 1/4 pitch. For example, in the case of the motor of FIG. 13, in the upper electromagnetic unit U2, the rotational positions of the S pole 31S of the magnetic pole 31 of the rotor 10 and the teeth 22 of the stator 20 coincide, and the lower electromagnetic unit U1. In FIG.

  In the case of the motor shown in FIG. 13, the rotational positions of the magnetic poles 31 of the rotors 10 of the two electromagnetic units U1 and U2 are aligned, and the rotational positions of the teeth 22 of the stator 20 are not aligned. Therefore, the rotational positions of the teeth 22 of the stator 20 are aligned and the rotational positions of the magnetic poles 31 of the rotor 10 are not aligned.

  When a predetermined current is supplied to each of the coils 25 of the two electromagnetic units U1 and U2, the electromagnetic units U1 and U2 generate rotational torque. Since the rotor 10 and the stator 20 of the two electromagnetic units U1 and U2 are mechanically connected to form the rotor and stator of the motor, the rotational torque generated in the rotor of the motor is the two electromagnetic units U1 and U1. This is the sum of U2 rotational torque (combined torque). Since this combined torque has a waveform in which pulsation is superimposed on a constant rotational torque, continuous rotational torque can be generated.

  When the magnetic pole 31 (S pole or N pole) of the rotor 10 and each tooth 22 of the stator 20 face each other (facing state), the magnetic flux generated by the magnetic pole 31 and the magnetic flux by the coil 25 are generated. This state is the most magnetically stable state and no rotational torque is generated. When the polarity of the current supplied to the coil 25 is reversed, the magnetic flux generated by the magnetic pole 31 and the polarity of the magnetic flux generated by the coil 25 are opposite to each other, so that the magnetically unstable state is obtained.

  When a current of a predetermined polarity is supplied to the coil 25 when the rotational position of the N pole 31N of the rotor 10 is slightly deviated from the facing state, the N pole 31N of the rotor 10 and the teeth 22 of the stator 20 are Rotational torque is generated in the direction of facing directly. Conversely, when a current having a polarity opposite to that of the polarity is supplied, rotational torque is generated in a direction in which the S pole 31S of the rotor 10 and the teeth 22 of the stator 20 are in the directly facing state.

  Therefore, when an electric current is supplied to the coil 25 of the stator 20 of the electromagnetic unit, an axial magnetic flux is generated in each tooth 22 of the stator 20, and the rotor 10 rotates about the shaft by the mechanism described above. The rotation of the rotor 10 is transmitted to a member (not shown) connected to the rotor 10. As described above, when the rotor 10 of the electromagnetic unit has the magnetic pole 31, the direction of the generated rotational torque changes depending on the polarity of the current supplied to the coil 25. In addition, when the rotor 10 has both the teeth 12 and the magnetic pole 31 made of a magnetic material such as iron or a dust core, a torque characteristic in which both characteristics are combined appears.

[Seventh embodiment]
The electromagnetic unit of the seventh embodiment will be described in detail below. However, since the configuration and operational effects of the electromagnetic unit of the seventh embodiment are substantially the same as those of the first to sixth embodiments, only different parts will be described, and description of the same parts will be omitted.
In the stator core 23 in the first to sixth embodiments, the joint strength of the joint portion between the stator yoke 21 and the teeth 22 is sufficient, but in order to reliably prevent the occurrence of cracks in the joint portion. Therefore, it is preferable to further increase the bonding strength of the bonded portion.

  First, the joint portion between the stator yoke 21 and the teeth 22 in each of the above embodiments will be described with reference to FIG. In the above embodiments, the average particle size of the component raw material powder and the main body portion raw material powder is not particularly limited, and the average particle size of both raw material powders may be the same. However, when the average particle diameters of both raw material powders are the same, as shown in FIG. 14, the meshing of the particles of both raw material powders in the joint portion is not good. As a result, there is a possibility that the occurrence of a crack or the like at the joint portion between the stator yoke 21 and the tooth 22 cannot be reliably prevented.

  Therefore, when the average particle size of the raw material powder for the main part is smaller than the average particle size of the raw material powder for the part, as shown in FIG. The particles of the raw material powder enter, and the meshing of the particles of both raw material powders at the joint portion of the stator yoke 21 and the teeth 22 becomes good. As a result, the joint strength of the joint portion between the stator yoke 21 and the teeth 22 becomes higher, and a high-strength stator core 23 is obtained.

  If the particle diameters of both raw material powders are reduced, the hysteresis loss of the stator core 23 increases and the magnetic permeability decreases. However, in general, portions other than the teeth 22 (such as the stator yoke 21) do not change much in magnetic flux density compared to the teeth 22, and are not easily saturated. Therefore, by using the raw material powder having a small particle size only for the portion other than the teeth 22, the deterioration of the magnetic characteristics in the entire stator core 23 can be suppressed to the minimum.

The average particle diameter of the component raw material powder is preferably 200 μm or more and 300 μm or less. If it is less than 200 μm, the joint strength of the joint portion between the stator yoke 21 and the teeth 22 may not be sufficiently improved. On the other hand, if it exceeds 300 μm, the eddy current loss of the stator core 23 may increase. The average particle size of the main body portion raw material powder is preferably 50 μm or more and 100 μm or less. If it is less than 50 μm, the magnetic permeability may decrease. On the other hand, if it exceeds 100 μm, the joint strength of the joint portion between the stator yoke 21 and the teeth 22 may not be sufficiently improved.
In addition, each said embodiment showed an example of this invention, Comprising: This invention is not limited to each said embodiment. For example, the structure of the electromagnetic unit and the motor and the shape of the dust core are not particularly limited, and the present invention can be applied to soft magnetic components having any structure.

  Hereinafter, the present invention will be described more specifically with reference to examples. A dust core for the iron core (stator core) of the motor having the same configuration as that of FIG. 1 was produced by the same manufacturing method as described above, and the motor of FIG. 1 was produced using this dust core. The motor characteristics were compared and evaluated. The dimensions of the stator yoke portion of the dust core are an outer diameter of 100 mm, an inner diameter of 70 mm, and a height of 10 mm, and the teeth portions have a length of 10 mm, a width of 10 mm, and a height of 20 mm. The number of teeth is ten.

  Unless otherwise specified, the magnetic powder contained in the component raw material powder and the main body part raw material powder is obtained by applying a phosphate coating to pure iron powder having an average particle size of 200 μm. Moreover, the binder mixed with the raw material powder for parts and the raw material powder for main part is an epoxy resin. Then, as the lubricant applied to the inner surface of the mold and the lubricant mixed with the raw material powder, zinc stearate was used.

[Pressing pressure during pressure molding]
As shown in Table 1, a raw material powder for a component in which a binder and a lubricant were mixed with magnetic powder was filled in a component molding die, and pressure molded to produce a component. The dimensions of the part are 6 mm in length, 6 mm in width, and 25 mm in height. Then, this part is placed in the mold for molding the powder core, and the raw material powder for the main body part (the same as the powder for parts) is mixed with the magnetic powder in the binder and lubricant. The mold was filled and pressure-molded to produce the dust cores of Example 1 and Comparative Example 1. As shown in FIG. 5, the fixing position of the component in the dust core is such that only the radially inner portion and the axial front end surface of the surface of the component are exposed from the stator yoke, and the other portions are covered by the stator yoke. I made it.

  As a comparative control of the dust cores of Example 1 and Comparative Example 1 produced in this way, the same material powder as the component raw material used in Example 1 and Comparative Example 1 was placed in the dust core molding die. Filled and pressure-molded to produce a conventional powder core. That is, the conventional example is one in which a dust core is produced by a production method comprising a one-stage pressure molding process as in the prior art, rather than a production method comprising a two-stage pressure molding process.

  When the characteristics of the motor incorporating these dust cores were evaluated, as shown in Table 1, if the press pressures when forming the parts and the dust core are equal as in Comparative Example 1, the motor characteristics are conventional. Although it is equivalent to the example, when the press pressure at the time of molding the part as in Example 1 is higher than the press pressure at the time of molding the dust core, the torque is improved over the conventional example. The torque and efficiency of each motor shown in Table 1 are shown as relative values when the torque and efficiency of the conventional motor are set to 1.

[About heat treatment]
The powder core of Example 1 described above was subjected to a heat treatment that was heated at 500 ° C. for 1 hour (referred to as Example 2), and the difference in the performance of the motor with and without the heat treatment was compared. The results are shown in Table 2. The torque and efficiency of each motor shown in Table 2 are shown as relative values when the torque and efficiency of the conventional motor are set to 1.
From Table 2, it can be seen that the iron loss of the dust core is reduced by the heat treatment, resulting in an increase in efficiency.

[About lubricant]
We examined whether the performance of the motor differs depending on whether the lubricant is mixed with the raw material powder for parts when using the mold lubrication method or not. The results are shown in Table 3. The torque and efficiency of each motor shown in Table 3 are shown as relative values when the torque and efficiency of the conventional motor are set to 1.
From Table 3, compared to Example 2 in which a component was manufactured by mixing a lubricant with component raw material powder, Example 3 in which a component was manufactured using a mold lubrication method was used because the density of the component was high. It can be seen that the torque is high.

[About Binder]
The difference in motor performance depending on the amount of binder contained in the raw powder was compared. The results are shown in Table 4. The torque and efficiency of each motor shown in Table 4 are shown as relative values when the torque and efficiency of the conventional motor are set to 1.
From Table 4, the content of the binder contained in the raw material powder for the part is different from that in Example 3 in which the content of the binder contained in the raw material powder for the part is equal to the content of the binder contained in the raw material powder for the main part. In Example 4 where the content of the binder contained in the partial raw material powder is smaller, it can be seen that the torque of the motor is high because the density of the parts is high.

[About impurities]
The difference in motor performance due to the concentration of impurities contained in the raw powder was compared. The results are shown in Table 5. The torque and efficiency of each motor shown in Table 5 are shown as relative values when the torque and efficiency of the conventional motor are set to 1.
From Table 5, Example 5 (concentration of impurities contained in the raw material powder for parts is lower than usual compared to Example 4 (1000 ppm) in which the concentration of impurities contained in the raw material powder for parts is a normal height. 100 ppm) shows that the motor efficiency is high.

[About flat processing]
The difference in the performance of the motor was compared depending on whether or not the magnetic powder used for the raw material powder for parts was flattened. The part was produced by pressure-molding the side surface (surface of height 25 mm × length or width 6 mm) as a press surface. The results are shown in Table 6. The torque and efficiency of each motor shown in Table 6 are shown as relative values when the torque and efficiency of the conventional motor are set to 1.
From Table 6, compared to Example 5 using normal magnetic powder that has not been flattened, Example 6 using flattened magnetic powder with a flat particle shape has a component permeability of It can be seen that the torque of the motor is high because it is high.

[Average particle size]
The difference in performance of the motor was compared when the average particle size of the main body part raw material powder and the part raw material powder was changed. The results are shown in Table 7. In addition, the manufacturing method of a compacting core is the same as that of Example 1 except the point from which the average particle diameter of the raw material powder for main body parts differs from the raw material powder for components. Further, the torque, efficiency, and mechanical strength of the dust core of each motor shown in Table 7 are relative values when the torque, efficiency, and mechanical strength of the dust core of Example 6 are set to 1, respectively. It is shown.

  As can be seen from Table 7, the average particle size of the main body part raw material powder is the average of the part raw material powder compared to Example 6 using the main body part raw material powder and the part raw material powder having the same average particle size. In Examples 7 to 10, which are smaller than the particle diameter, the torque and the efficiency are almost equal, and the mechanical strength is remarkably improved. On the other hand, in Example 11, since the average particle size of the raw material powder for the main body portion is less than 50 μm, although mechanical strength is improved as compared with Examples 7, 8, and 9, torque and efficiency are low. I understand that. Moreover, since the average particle diameter of the main body part raw material powder is larger than 100 μm in Example 12, it can be seen that mechanical strength is less improved than in Examples 7, 8, and 9. From the above, it can be seen that when the average particle size of the main body part raw material powder is 50 μm or more and 100 μm or less, the mechanical strength can be improved without greatly reducing the torque and efficiency.

  On the other hand, in Example 13, since the average particle size of the component raw material powder is less than 200 μm, it can be seen that mechanical strength is less improved than in Examples 7 and 10. Furthermore, in Example 14, since the average particle diameter of the raw material powder for parts is larger than 300 μm, although the strength is improved compared to Examples 7 and 10, the efficiency is decreased. From the above, it can be seen that when the average particle size of the component raw material powder is 200 μm or more and 300 μm or less, the mechanical strength can be improved without greatly reducing the efficiency.

DESCRIPTION OF SYMBOLS 10 Rotor 11 Rotor yoke 12 Teeth 20 Stator 21 Stator yoke 22 Teeth 23 Stator core 25 Coil U1, U2, U3 Electromagnetic unit 31S S pole 31N N pole

Claims (9)

A method for producing a powder core having a shape in which one or more protrusions protrude from a main body part by press-molding a raw material powder containing magnetic powder,
A first molding step in which component raw material powder is filled in a component molding die and pressed at a predetermined pressing pressure to produce one or more types of components;
One or more of each of the various parts obtained in the first molding step is placed in a compacting core molding die, the part forms the protrusion , and one end of the part is embedded in the main body. And a configuration in which a radially outer diameter side portion of the component is covered by the main body portion, or only a radial inner diameter side portion and an axial front end surface of the surface of the component are exposed from the main body portion. The part is arranged at a predetermined position in the powder core molding die so that the part is covered with the body part, and the raw material powder for the body part is used as the powder core molding metal. A second molding step of filling the mold and press-molding with a predetermined press pressure to obtain the dust core;
With
Each of the press pressures when molding the various parts in the first molding step is higher than the press pressure when molding the dust core in the second molding step. A method for producing a dust core.   The method for producing a dust core according to claim 1, further comprising a heat treatment step of heat-treating the dust core obtained in the second molding step.   When molding at least one of the various parts in the first molding step, the powder molding core is molded in the second molding step using the component molding die having an inner surface coated with a lubricant. In the process, the powder for core body according to claim 1 or 2, wherein the raw material powder for main body portion containing a lubricant is used.   The component raw material powder and the main body part raw material powder contain a binder, and the content of the binder contained in the component raw material powder used when molding at least one of the various components is determined by the main body. The method for producing a powder core according to any one of claims 1 to 3, wherein the content is less than the content of the binder contained in the raw material powder for partial use.   The concentration of impurities contained in the component raw material powder used when molding at least one of the various components is lower than the concentration of impurities contained in the main body portion raw material powder and less than 1000 ppm. The manufacturing method of the powder core as described in any one of Claims 1-4 characterized by the above-mentioned.   The powder core according to any one of claims 1 to 5, wherein the component raw material powder used when molding at least one of the various components is flattened. Manufacturing method.   The method for producing a dust core according to any one of claims 1 to 6, wherein an average particle size of the raw material powder for the main body part is smaller than an average particle size of the raw material powder for parts.   8. The method for producing a dust core according to claim 7, wherein an average particle diameter of the raw material powder for the main body portion is 50 μm or more and 100 μm or less, and an average particle diameter of the raw material powder for parts is 200 μm or more and 300 μm or less. .   It is a powder core of the shape obtained by press-molding the raw material powder containing magnetic powder, and the one or more protrusion parts protruded from the main-body part, Comprising: It is a powder core with any one of Claims 1-8. A dust core produced by the method for producing a dust core according to claim 1.

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