JP2020078231A - Multiple motor products, motor, motor group, drive device, and magnet group - Google Patents

Abstract

To provide a motor that can suppress cogging torque.SOLUTION: Each of 30 or more identical motor products on the market includes one or more magnets, the magnet has a void ratio of 7% or less, is a sintered magnet having a non-parallel oriented region, and has a first main surface having a maximum surface magnetic flux density peak value, and in the first main surface of the magnet, when the surface magnetic flux density is measured across a measurement line, the following formula of deviation variation P between magnets satisfied by P[%]=(σ[mT]/A[mT])×100 is 4% or less.SELECTED DRAWING: Figure 40

Description

  The present invention relates to a motor and a group of motors including a magnet, and a driving device including such a magnet.

  Motors (electric motors) that convert electrical energy into mechanical kinetic energy are widely used in the fields of machine tools, vehicles, aircraft, and the like. Such a motor is equipped with a permanent magnet, and as the permanent magnet, for example, a parallel-oriented rectangular magnet with easy axes of magnetization aligned in parallel, a polar anisotropic ring magnet, or the like is used.

  However, it is known that current motors have a phenomenon called cogging torque, in which a magnetic attraction force between an armature and a rotor pulsates with respect to a rotation angle. Since such a cogging torque causes vibration and noise of the motor, it is desired to reduce it as much as possible.

  For example, Patent Document 1 proposes to use a polar anisotropic ring magnet whose magnetization direction is controlled in a specific direction in order to suppress cogging torque.

JP, 2005-44820, A

  Various permanent magnets have been proposed so far in order to suppress cogging torque.

  However, even in the conventional motor including the permanent magnet, it is difficult to say that the effect of suppressing the cogging torque is sufficient, and a measure capable of further suppressing the cogging torque is still required.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a motor and a motor group that can further suppress the cogging torque. Another object of the present invention is to provide a drive device including such a motor or a group of motors.

In the present invention, the same plurality of commercially available motor products,
There are over 30 motor products,
Each motor product contains one or more magnets,
Each magnet has a void fraction of 7% or less,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

A plurality of motor products having a deviation variation P between magnets of 4% or less are provided.

Here, the measurement line, when the cross section in which the non-parallel oriented region is recognized is referred to as a specific cross section, in the substantially center of the first main surface, along the direction parallel to the specific cross section, 1 represents a measurement locus corresponding to the entire main surface, and the measurement line is defined at a spatial position 1 mm above the first main surface,
A _total represents the total average surface magnetic flux density, and when the absolute values of the surface magnetic flux densities at the same measurement positions on the measurement lines of the respective sintered magnets were averaged, and this was taken as B _ave [mT], the measurement was performed. Calculated by summing the average values B _ave [mT] at all measurement positions on the line,
σ _total represents the total standard deviation, and the standard deviation of the surface magnetic flux density at each measurement position used for the calculation of the total average surface magnetic flux density A _total on the measurement line in each sintered magnet is σ [mT]. Then, the standard deviation σ [mT] at all the measurement positions on the measurement line is calculated.

Further, in the present invention,
A motor having a plurality of magnets,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

There is provided a motor in which the deviation variation P between the magnets represented by is 4% or less.

Further, in the present invention,
A series of motor groups having a plurality of motors,
Each motor has one magnet
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

There is provided a motor group in which the deviation variation P between the magnets represented by is 4% or less.

  Furthermore, the present invention provides a drive device having a motor or a motor group having the above-described characteristics.

Further, in the present invention, a magnet group including a plurality of magnets,
Each magnet has a void fraction of 7% or less,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

There is provided a magnet group in which the deviation variation P between magnets represented by is 4% or less.

  In the present invention, the void fraction of each magnet is preferably 5% or less, more preferably 3% or less, and further preferably 1% or less.

  In the present invention, the deviation variation P [%] between magnets is preferably 3% or less, and more preferably 2% or less.

  According to the present invention, it is possible to provide a motor and a motor group that can further suppress the cogging torque. Further, according to the present invention, it becomes possible to provide a drive device including such a motor or a motor group.

FIG. 3 is a diagram schematically showing a cross section of a motor according to an embodiment of the present invention. It is the figure which showed typically an example of the sintered magnet with which the motor shown in FIG. 1 was equipped. It is the figure which showed typically the cross section along the S1-S1 line of the sintered magnet in FIG. FIG. 3 is a diagram schematically showing a surface magnetic flux density distribution on each of a first main surface and a second main surface in a sintered magnet having a polar anisotropic orientation of an easy axis of magnetization. It is the figure which showed typically the operation at the time of defining the measurement start end part on a measurement line in a rectangular parallelepiped sintered magnet. It is the figure which showed typically the operation at the time of defining the measurement start end part on a measurement line in a rectangular parallelepiped sintered magnet. FIG. 6 is a diagram schematically showing a cross section of a motor according to another embodiment of the present invention. FIG. 8 is a diagram schematically showing an example of a sintered magnet mounted on the motor shown in FIG. 7. It is the figure which showed typically the cross section of the sintered magnet shown in FIG. It is the figure which showed typically the operation at the time of determining the measurement starting point and the measurement direction on the measurement line in a ring-shaped sintered magnet. It is the figure which showed typically the operation at the time of determining the measurement starting point and the measurement direction on the measurement line in a ring-shaped sintered magnet. It is a figure for demonstrating the method of determining parallel alignment / non-parallel alignment by the EBSD method. It is the figure which showed typically the cross section perpendicular to the axial direction of the IPM motor. It is the figure which showed typically the cross section parallel to the moving direction of a linear motor. FIG. 3 is a diagram schematically showing a motor group according to an embodiment of the present invention. It is the figure which showed typically the cross section of the inner rotor type rotation motor which a magnet rotates. It is the figure which showed typically the cross section of the outer rotor type rotation motor which a coil rotates. It is the figure which showed typically the cross section of the outer rotor type rotation motor with which a magnet rotates. It is the figure which showed typically the cross section of the inner rotor type rotation motor which a coil rotates. It is the figure which showed typically the cross section of the moving coil type linear motor with a core. It is the figure which showed typically the cross section of the moving magnet type linear motor with a core. It is the figure which showed typically the cross section of the coreless moving coil type linear motor. It is the figure which showed typically the cross section of the coreless moving magnet type linear motor. FIG. 6 is a diagram schematically showing an example of a flow of a method for manufacturing a sintered magnet applied to the motor according to the embodiment of the present invention. It is the figure which showed typically one structure of the jig which can be used for the pressure sintering process of a ring-shaped calcined body. It is the figure which showed typically the shape of the sintered magnet manufactured in Example 1. It is the figure which showed collectively the measurement result of the surface magnetic flux density in each sintered magnet manufactured in Example 1. It is the figure which showed collectively the measurement result of the surface magnetic flux density in each sintered magnet manufactured in Example 2. It is the figure which showed collectively the measurement result of the surface magnetic flux density in each sintered magnet manufactured in Example 3. It is the figure which showed collectively the measurement result of the surface magnetic flux density in each sintered magnet manufactured in Example 4. It is the figure which showed an example of the image obtained at the time of measuring the void of the sintered magnet in an Example. It is the figure which showed typically the shape of the sintered magnet used in Example 11. It is the figure which showed an example of the image obtained at the time of measuring the void of the sintered magnet in a comparative example. It is the figure which showed typically the shape of the sintered magnet used in Example 12. It is the figure which showed an example of the image obtained at the time of measuring the void of the sintered magnet in a comparative example. It is the figure which showed typically the structure of the apparatus used for the simulation. FIG. 37 is a schematic enlarged view of a portion surrounded by a thick frame in FIG. 36. 9 is a graph showing the relationship between the deviation variation between magnets P and the cogging torque width ΔT obtained by simulation. It is the figure which showed the geometrical dimension of the motor used for the simulation in the 4th apparatus. It is a graph which shows the deviation P between magnets obtained by the simulation in a 4th apparatus, and the relationship of the average of a harmonic amplitude ratio. It is the figure which showed typically the focus coordinate used for the simulation in the 5th apparatus. It is the figure which showed the geometrical dimension of the motor used for the simulation in a 5th apparatus. It is a graph which shows the variation variation P between magnets obtained by the simulation in a 5th apparatus, and the average of a harmonic amplitude ratio.

  An embodiment of the present invention will be described below with reference to the drawings.

  In the following description, the “first main surface” of the magnet means the surface of the magnet that can obtain the surface magnetic flux density having the “maximum” peak value. Further, the “second main surface” of the magnet means a surface located on the opposite side of the first main surface. Furthermore, the "thickness" of the magnet means the distance between the first major surface and the second major surface.

  In the surface magnetic flux density, the peak value being “maximum” means that the peak value is farthest from the reference 0 (zero) regardless of whether the peak value is positive or negative.

(Motor according to an embodiment of the present invention)
FIG. 1 schematically shows a cross section of a motor according to an embodiment of the present invention.

  As shown in FIG. 1, a motor (hereinafter, referred to as “first device”) 101 according to an embodiment of the present invention includes a rotor 112 rotatably installed around a shaft 110 and a rotor 112 surrounding the rotor 112. And a stator 114. A coil 118 having a predetermined number of turns is installed on the stator 114 at a predetermined position.

  The rotor 112 has a plurality of sintered magnets 120. For example, in the example shown in FIG. 1, the rotor 112 has a total of four sintered magnets 120. Note that the number of sintered magnets included in the rotor 112 is not particularly limited as long as it is plural. For example, the rotor 112 may have an even number of sintered magnets 120.

  FIG. 2 schematically shows an example of the shape of the sintered magnet 120 mounted on the first device 101.

  In the example shown in FIG. 2, the sintered magnet 120 has a substantially rectangular parallelepiped shape. That is, the sintered magnet 120 has a first surface 130 and a second surface 132 facing each other, and four side surfaces connecting the both surfaces 130, 132. The four side surfaces are respectively referred to as a first side surface 136, a second side surface 137, a third side surface 138, and a fourth side surface 139 counterclockwise.

  Here, the first surface 130 is the first main surface and the second surface 132 is the second main surface. That is, it is assumed that the sintered magnet 120 has the maximum surface magnetic flux density on the first surface 130.

  As shown in FIG. 2, each surface of the sintered magnet 120 is associated with three orthogonal axes (XYZ axes).

  That is, the first surface 130 and the second surface 132 are parallel to the XY plane, the first side surface 136 and the third side surface 138 are parallel to the XZ plane, and the second side surface 137 and the fourth side surface 137. The side surface 139 of is parallel to the YZ plane.

  The dimension L of the first surface 130 and the second surface 132 in the X direction is referred to as the “length” of the sintered magnet 120, and the dimension W of the first surface 130 and the second surface 132 in the Y direction is This is referred to as the “width” of the sintered magnet 120.

  According to the above definition, the distance between the first surface 130 and the second surface 132, that is, the dimension t of each side surface 136 to 139 in the Z direction is the “thickness” of the sintered magnet 120.

  Here, the sintered magnet 120 is formed by sintering magnet material particles. Each magnet material particle has an easy axis of magnetization.

  FIG. 3 schematically shows a cross section taken along line S1-S1 in FIG. 2, that is, a direction substantially parallel to the width W of the sintered magnet 120 and parallel to the XZ plane.

  In FIG. 3, each line segment in the cross section 160 represents the orientation direction of the easy axis of magnetization of the magnet material particles. Further, the arrow of the line segment represents the magnetization direction.

  As shown in FIG. 3, the cross section 160 of the sintered magnet 120 has a region 162 in which the easy axis of magnetization of the magnet material particles is “polar anisotropic orientation”.

  Here, the “polar anisotropic orientation of the easy axis of magnetization” of the permanent magnet means that the maximum surface magnetic flux density is twice or more different between the first main surface and the second main surface of the permanent magnet. Such an orientation of the easy axis of magnetization. For example, “polar anisotropic orientation of the easy axis of magnetization” of a permanent magnet includes a configuration in which the easy axis of magnetization of magnet material particles is arranged to gradually change along a predetermined direction.

  This feature will be described in more detail with reference to FIG.

  FIG. 4 schematically shows the surface magnetic flux density distribution on each of the first main surface and the second main surface in the permanent magnet having the polar anisotropic orientation of the easy axis of magnetization. The measurement position (horizontal axis) is a direction perpendicular to the width direction of the permanent magnet.

  As shown in FIG. 4, in the permanent magnet having the polar anisotropic orientation of the easy axis of magnetization, the first main surface has a surface magnetic flux density distribution having a larger peak value than the other surfaces. The two main surfaces are characterized in that such a surface magnetic flux density distribution cannot be obtained. That is, the surface magnetic flux density distributions that are significantly different are obtained between the first main surface and the second main surface.

Here, in the surface magnetic flux density distribution as shown in FIG. 4, the area surrounded by the surface magnetic flux density curve obtained on the first main surface and the horizontal axis is P ₁ . The area enclosed by the surface magnetic flux density curve obtained on the second main surface and the horizontal axis is P ₂ . When specified in this way, a typical permanent magnet having a magnetically easy axis oriented in polar anisotropy is characterized in that the ratio P ₁ / P ₂ is 2 or more, for example 3 or more.

  By the way, in the sintered magnet 120, the polar-anisotropically oriented region 162 as shown in FIG. 3 does not have to exist in all the cross sections parallel to the thickness direction, and the cross section parallel to the thickness direction does not have to exist. It only needs to exist in at least one of them. Hereinafter, the cross section in which such polar anisotropically oriented region 162 is recognized is also particularly referred to as a “specific cross section”.

  For example, in the case of the sintered magnet 120, in the cross section parallel to the X direction of the sintered magnet 120 in FIG. 2, a polar-anisotropically oriented region 162 as shown in FIG. 3 is observed. Therefore, the cross section parallel to the X direction (XZ plane) is the specific cross section. However, it should be noted that in the cross section of the sintered magnet 120 parallel to the Y direction (YZ plane), no regions having polar anisotropy orientation are observed, and the cross section in this direction is not a specific cross section. .

  When the specific cross section is defined in this way, in the substantially rectangular parallelepiped sintered magnet 120, the above-mentioned “length L” can also be defined as the dimension of the connecting portion connecting the first main surface and the specific cross section. The “width W” can also be defined as the dimension in the direction perpendicular to the direction of the length L and perpendicular to the direction of the thickness t.

Referring to FIG. 2 again, each sintered magnet 120 mounted on the first device 101 has a direction parallel to the specific cross section at substantially the center in the width direction of the first main surface (that is, the first surface 130). When the surface magnetic flux density is measured in a region extending from one end to the other end of the sintered magnet 120 along (X direction in FIG. 2), the following formula (1) is obtained.

Deviation variation between magnets P [%] =
(Σ _total [mT] / A _total [mT]) × 100 (1) Expression

The deviation variation P between magnets represented by is less than 4%.

  Here, in the present application, the measurement locus over the entire first main surface along the direction parallel to the specific cross section at the approximate center in the width direction of the first main surface of the sintered magnet 120 is referred to as a “measurement line”. To call.

Further, in the formula (1), A _total [mT] represents the total average surface magnetic flux density. This total average surface magnetic flux density A _total [mT] is obtained by averaging the absolute values of the surface magnetic flux densities at the same measurement positions on the measurement lines of the respective sintered magnets 120, and taking this as B _ave [mT], It is determined by summing the average values B _ave [mT] at all the measurement positions on the measurement line.

Further, σ _total [mT] represents the total standard deviation. The total standard deviation σ _total [mT] is the standard deviation of the surface magnetic flux density at each measurement position used for calculating the total average surface magnetic flux density A _total [mT] on the measurement line of each sintered magnet 120. When [mT] is used, the standard deviation σ [mT] at all measurement positions on the measurement line can be obtained by summing.

  For example, in the examples shown in FIGS. 2 and 3, the sintered magnet 120 has the first surface 130 as the first main surface and the XZ plane as the specific cross section, and therefore the measurement line is the first surface 130. Is a straight line portion approximately parallel to the center in the width direction from the second side surface 137 to the fourth side surface 139 (or vice versa).

Further, the total average surface magnetic flux density A _total [mT] is obtained by measuring the absolute value of the surface magnetic flux density at the same position on the measurement line in the four sintered magnets 120, and from these, the average value B _ave [at that position]. mT] is calculated, this is carried out at all positions on the measurement line, and the obtained average values B _ave [mT] are summed.

Similarly, the total standard deviation σ _total [mT] is the standard deviation σ [mT] at each measurement position on the measurement line selected for obtaining the average value B _ave [mT] described above in the four sintered magnets 120. ], This is carried out at all positions on the measurement line, and the obtained standard deviation σ [mT] is summed up.

  If the measurement line is selected so as to be in direct contact with the first main surface of the sintered magnet 120, it may be difficult to accurately evaluate the surface magnetic flux density due to the shape of the first main surface and the like. Therefore, in the present application, the measurement line is selected in the space 1 mm above the first main surface of the sintered magnet 120.

  Further, it is preferable that the measurement points on the measurement line are separated by a constant distance, and in this case, the distance between the measurement points at two adjacent points is 4 μm.

  The variation deviation P [%] between magnets represented by the equation (1) can be used as an index representing the variation in magnetic characteristics of the plurality of sintered magnets 120 used in the motor. That is, it can be said that the smaller the P value, the smaller the variation in characteristics among the used sintered magnets 120.

  As described above, the conventional motor has a problem that it is difficult to sufficiently suppress the cogging torque.

  On the other hand, the sintered magnet 120 mounted on the first device 101 is characterized in that the deviation variation P represented by the equation (1) is suppressed to 4% or less as described above.

  When the sintered magnet 120 having such characteristics is used, characteristic variations among the magnets are significantly suppressed, and the cogging torque of the motor can be significantly suppressed. Therefore, in a motor including a plurality of such sintered magnets 120, it is possible to significantly suppress vibration and noise.

  When measuring the surface magnetic flux density, if the measurement start end and the measurement direction on the measurement line are not determined for each sintered magnet 120, the obtained data may not be able to be compared with each other. In this case, it becomes impossible to accurately evaluate the deviation variation P between the magnets.

  For example, in the normal case, the surface magnetic flux density data obtained by measuring the measurement line in the direction from the second side surface 137 to the fourth side surface 139 and the measurement line in the direction from the fourth side surface 139 to the second side surface 137 are used. The measured surface magnetic flux density data cannot be directly compared. Further, it is difficult to distinguish the difference between the second side surface 137 and the fourth side surface 139 of each sintered magnet 120 only by visually recognizing each sintered magnet 120.

  Therefore, in the present application, the measurement start end portion and the measurement direction of the sintered magnet 120 are determined as shown in FIGS. 5 and 6 below. 5 and 6 schematically show an operation procedure for determining the measurement direction, that is, the measurement start end portion.

  First, the surface magnetic flux density in each sintered magnet 120 is measured along a measurement line from an arbitrarily determined measurement start end to the opposite end. As a result, in each sintered magnet 120, a relationship (hereinafter referred to as “acquired data”) between the measurement position (horizontal axis) and the surface magnetic flux density (vertical axis) as shown in FIG. 5 is obtained. Here, the measurement direction is provisionally determined from the end 1 to the end 2.

  Next, as shown in FIG. 6, in the acquired data, data obtained by converting the surface magnetic flux density into an absolute value (hereinafter, referred to as “absolute value data”) is obtained. The absolute value data can be obtained by bending the measurement result shown in FIG. 5 along the X axis.

Next, in the absolute value data, the maximum peak P _max is determined. Further, one of the end 1 and the end 2 which is closer to the position of the maximum peak P _max is selected, and this is set as the measurement start end. For example, in the example shown in the figure, the end 1 is the measurement start end.

When there are two or more peaks having the same maximum value, the area surrounded by the X axis in each peak is determined, and the one having the larger area is defined as the maximum peak P _max .

It is also assumed that the position of the maximum peak P _max is exactly equidistant from the end 1 and the end 2. In that case, the absolute value data and the area of the region surrounded by the X axis are obtained from the position of the maximum peak P _max , that is, from the center between the end portions 1 and 2 toward each end portion. The end portion included in the larger area of the area including the end portion 1 and the area including the end portion 2 is defined as the measurement start end portion.

  Next, the direction from the measurement start end to the other end is determined as the surface magnetic flux density measurement direction.

  Based on the measurement start end and the measurement direction determined in this way, the acquired data is converted and converted data is obtained.

  When the conversion data obtained in this way is used, the measurement start end and the measurement direction can be aligned in each sintered magnet 120. Further, this makes it possible to accurately evaluate the deviation variation P between the magnets.

  In this way, in each sintered magnet 120, the measurement direction for measuring the surface magnetic flux density is determined.

(Other characteristics of the sintered magnet 120)
The sintered magnet 120 used in the first device 101 is not particularly limited, but may be, for example, a rare earth sintered magnet.

  In that case, the sintered magnet 120 may include R (R is one or more of rare earth elements including Y), B (boron), and Fe (iron). The content of each component is, for example, R = 27 wt% to 40 wt% (preferably 28 wt% to 35 wt%, more preferably 28 wt% to 33 wt%), B = 0.6 wt% to 2 wt% (preferably 0. 6 wt% to 1.2 wt%, more preferably 0.6 wt% to 1.1 wt%).

  The sintered magnet 120 may be, for example, an Nd-Fe-B based magnet.

  Further, the sintered magnet 120 is made of Co, Cu, Al, Si, Ga, Nb, V, Pr, Mo, Zr, Ta, Ti, W, Ag, Bi, Zn, and / or Mg in order to improve magnetic properties. Other elements and unavoidable impurities may be included in small amounts.

  The dimension of the sintered magnet 120 is not particularly limited, but the length L may be, for example, in the range of 5 mm to 40 mm. Further, the width W of the sintered magnet 120 may be in the range of 10 mm to 150 mm. Furthermore, the thickness t of the sintered magnet 120 may be in the range of 1.5 mm to 8 mm.

(Motor according to another embodiment of the present invention)
Next, with reference to FIG. 7, a motor according to another embodiment of the present invention will be described.

  FIG. 7 schematically shows a cross section of a motor according to another embodiment of the present invention.

  As shown in FIG. 7, a motor (hereinafter, referred to as “second device”) 201 has a rotor 212 rotatably installed around a shaft 210, and a stator 214 surrounding the rotor 212. A coil 218 having a predetermined number of turns is installed on the stator 214 at a predetermined position.

  The rotor 212 has a plurality of sintered magnets 220. For example, in the second device 201, the rotor 212 includes a total of four sintered magnets 220 along the axial direction of the shaft 210, although it is hard to see from FIG. 7. Note that the number of sintered magnets included in the rotor 212 is not particularly limited as long as it is plural. For example, the rotor 212 may have an even number of sintered magnets 220.

  FIG. 8 schematically shows an example of the shape of the sintered magnet 220 mounted on the second device 201.

  In the example shown in FIG. 8, the sintered magnet 220 has a substantially ring shape. That is, the sintered magnet 220 has a first surface 230 and a second surface 232 facing each other, and an outer surface 236 and an inner surface 237 connecting the two surfaces 230, 232.

  Here, the outer side surface 236 is the first main surface and the inner side surface 237 is the second main surface. That is, it is assumed that the sintered magnet 220 has the maximum surface magnetic flux density on the outer surface 236.

  Here, as shown in FIG. 8, the sintered magnets 220 are associated with each other by three axes (XYZ axes) orthogonal to each other. That is, the first surface 230 and the second surface 232 are parallel to the XZ plane, and the outer surface 236 and the inner surface 237 extend parallel to the Y direction.

  According to the above definition, the dimension between the outer side surface 236 and the inner side surface 237 is the thickness t. In the sintered magnet 220, the distance W between the first surface 230 and the second surface 232 is defined as “width”.

  FIG. 9 schematically shows a cross section along the direction parallel to the XZ plane in the approximate center of the width W of the sintered magnet 220.

  In FIG. 9, each line segment in the cross section 260 represents the orientation direction of the easy axis of magnetization of the magnet material particles. Further, the arrow of the line segment represents the magnetization direction.

  As shown in FIG. 9, the cross section 260 of the sintered magnet 220 has a region 262 in which the easy axis of magnetization of the magnet material particles is “polar anisotropic orientation”. As described above, the cross section in which the polar-anisotropically oriented region 262 is recognized is particularly referred to as a “specific cross section”.

  As is clear from FIG. 9, the specific cross section is parallel to the XZ plane.

  When such a specific cross section is defined, in the substantially ring-shaped sintered magnet 220, the above-mentioned “connecting portion” is the portion that connects the first main surface and the specific cross section (the first surface 230 or the second surface). It becomes the outer circumference of the surface 232. The "width W" can also be defined as the dimension in the direction perpendicular to the connecting portion and perpendicular to the thickness t direction.

Each of the sintered magnets 220 mounted on the second device 201 has the following values when the surface magnetic flux density is measured over the “measurement line” at approximately the center in the width direction of the first main surface (that is, the outer surface 236). Formula (1)

Deviation variation between magnets P [%] =
(Σ _total [mT] / A _total [mT]) × 100 (1) Expression

The deviation variation P between magnets represented by is less than 4%.

  As described above, the “measurement line” means a measurement locus over the first main surface along a direction parallel to the specific cross section.

  Therefore, in the example shown in FIG. 8 and FIG. 9, the measurement line in the sintered magnet 220 is one outer circumference of the sintered magnet 220 along the plane parallel to the XZ plane at the approximate center in the width direction of the outer surface 236. Minutes (accurately, the outer circumference is 1 mm away from the outer side surface 236).

The total average surface magnetic flux density A _total [mT] and the total standard deviation σ _total [mT] are as defined above.

Therefore, in the examples shown in FIGS. 8 and 9, the total average surface magnetic flux density A _total [mT] of the sintered magnets 220 is the same as the surface magnetic flux density of the four sintered magnets 220 at the same position on the measurement line. By measuring the absolute values, calculating from them the mean value B _ave [mT] at that position, carrying out this at all positions on the measuring line and summing the obtained mean values B _ave [mT] Desired.

Similarly, the total standard deviation σ _total [mT] is the standard deviation σ [mT] in each of the four sintered magnets 220 at each measurement position on the measurement line selected to obtain the above-mentioned average value B _ave [mT]. ], This is carried out at all positions on the measurement line, and the obtained standard deviation σ [mT] is summed up.

  However, as described above, the actual measurement line is set at the spatial position 1 mm above the first main surface.

  In addition, it is preferable that the measurement points on the measurement line be separated at regular intervals. In this case, the two adjacent measurement points are selected such that the center angle centered on the center C (see FIG. 9) of the specific cross section of the sintered magnet 220 is 0.04 °.

  The variation deviation P [%] between magnets represented by the equation (1) can be used as an index representing the variation in magnetic characteristics of the plurality of sintered magnets 220 used in the motor. That is, it can be said that the smaller the P value, the smaller the variation in characteristics among the used sintered magnets 220.

  Therefore, in a motor including a plurality of such sintered magnets 220, vibration and noise can be significantly suppressed.

  When measuring the surface magnetic flux density, the obtained data may not be able to be compared with each other unless the measurement starting point and the measurement direction on the measurement line are determined for each sintered magnet 220. In this case, it becomes impossible to accurately evaluate the deviation variation P between the magnets.

  Therefore, in the present application, the measurement start point and the measurement direction on the measurement line of the sintered magnet 220 will be determined as shown in FIGS. 10 and 11 below. 10 and 11 schematically show an operation procedure for determining the measurement start point and the measurement direction.

  First, the surface magnetic flux density in each sintered magnet 220 is measured along an arbitrary direction from an arbitrarily determined measurement start point along the measurement line. As a result, in each sintered magnet 220, a relationship (hereinafter referred to as “acquired data”) between the mechanical angle (horizontal axis) and the surface magnetic flux density (vertical axis) as shown in FIG. 10 is obtained.

  Next, as shown in FIG. 11, in the acquired data, data obtained by converting the surface magnetic flux density into an absolute value (hereinafter, referred to as “absolute value data”) is obtained. The absolute value data can be obtained by bending the measurement result shown in FIG. 10 along the X axis.

Next, in the absolute value data, the maximum peak P _max is determined. In addition, the two closest peaks to the maximum peak _Pmax are defined on both sides of the determined maximum peak _Pmax, and the peaks are designated as the first peak P ₁ and the second peak P ₂ . In addition, the larger one of the first peak P ₁ and the second peak P ₂ is selected as the specific proximity peak P _n . For example, in the example shown in the figure, the first peak P ₁ becomes the specific proximity peak P _n .

When there are two or more peaks having the same maximum value, the area surrounded by the X axis in each peak is determined, and the one having the larger area is defined as the maximum peak P _max .

Next, a position between the specific proximity peak P _n and the maximum peak P _max at which the surface magnetic flux density becomes zero is set as a measurement start point of the surface magnetic flux density. Further, the direction from the measurement start point to the maximum peak P _max is the measurement direction.

  Based on the measurement start point and the measurement direction thus determined, the acquired data is converted and converted data is obtained.

  When the conversion data obtained in this way is used, the measurement start point on the measurement line and the measurement direction can be aligned in each sintered magnet 220. Further, this makes it possible to accurately evaluate the deviation variation P between the magnets.

  In some sintered magnets, the first main surface may not be represented by a substantially flat surface or a substantially circular shape. In such a case, the measurement line is selected from the above-described linear locus and circumferential locus that can more stably evaluate the surface magnetic flux density.

(Other characteristics of the sintered magnet 220)
The material and the like of the sintered magnet 220 used in the second device 201 are the same as those of the above-described sintered magnet 120.

  The size of the sintered magnet 220 is not particularly limited, but the width W may be, for example, in the range of 10 mm to 150 mm. The outer diameter of the sintered magnet 220 may be in the range of 8 mmφ to 60 mmφ, for example. Furthermore, the thickness t of the sintered magnet 220 may be in the range of 1.5 mm to 6 mm.

  The features according to the embodiment of the present invention have been described above by taking the rectangular sintered magnet 120 and the ring-shaped sintered magnet 220 as examples. However, the shape of the magnet used in the present invention is not particularly limited. In another embodiment of the present invention, for example, the ring-shaped sintered magnet 220 may be divided into two, three, four, or more, and segmented sintered magnets may be used.

  Further, in the above example, one feature of the present invention has been described by taking the motors 101 and 201 including the sintered magnets 120 and 220 having polar anisotropy as an example.

  However, the magnet used in the motor according to the present invention is not limited to the sintered magnet having polar anisotropy. That is, in the present invention, any sintered magnet having a region of "non-parallel orientation" can be applied as long as the variation P between magnets obtained by the above-mentioned formula (1) is 4% or less.

  Here, the non-parallel orientation means an orientation other than the parallel orientation. Specifically, the non-parallel orientation means all orientations having regions having crystal orientations different by 20 ° or more. The non-parallel orientation includes, for example, polar anisotropic orientation and radial orientation.

  In the above description, the "specific cross section" is defined as the cross section 160, 260 having the polar anisotropically oriented regions 162, 262. However, hereinafter, not only the polar anisotropic orientation but also a cross section having a region of orientation other than the parallel orientation is broadly defined as a “specific cross section”.

  Therefore, “a magnet having a non-parallel orientation region” means a magnet having a region having a different crystal orientation of 20 ° or more in the “specific cross section”.

  Further, whether or not a given sintered magnet has a non-parallel orientation region can be determined by using an EBSD (Electron Back Scatter Diffraction Patterns) method.

  Hereinafter, a method for determining parallel alignment / non-parallel alignment by the EBSD method will be specifically described with reference to FIG.

  FIG. 12 shows a cross section AP perpendicular to the first main surface of the substantially rectangular parallelepiped sintered magnet. The cross section AP is a cross section parallel to the moving direction of the motor and a direction perpendicular to the first main surface.

Whether or not the cross-section AP has regions of non-parallel orientation is determined by the following method:
(I) In the cross section AP, a line segment (hereinafter, referred to as a “dividing line CL”) that connects the substantially centers in the thickness (t) direction is determined.
(Ii) Each point that divides the dividing line CL into eight equal parts (hereinafter referred to as "point CP") is determined.
(Iii) At each point CP, in the 100 μm × 100 μm region, the orientation vector of the easy axis of magnetization (the direction with the highest frequency) is measured by the EBSD method. Depending on the size of the magnetic material particles forming the sintered magnet, the measurement area is selected at an appropriate time. If the measurement is performed so that 30 or more magnet material particles are included in each visual field, the orientation vector of the easy axis of magnetization can be determined.
(IV) The orientation vectors at all points CP are compared, and when the maximum angle difference is 20 ° or more, the cross section is determined to be a specific cross section and has a non-parallel alignment region.

The above method can be applied to the case of a substantially ring-shaped sintered magnet such as the sintered magnet 220 shown in FIGS. 8 and 9. However, in the cross-section AP, the “line segment” connecting the substantially centers in the thickness (t) direction becomes the “circumference”. Therefore, in this case the following evaluations are carried out:
(I ') In the cross section AP, a circumference (hereinafter referred to as a "dividing line CL") that connects substantially centers in the thickness (t) direction is determined.
(Ii ′) Each point (hereinafter, referred to as “point CP”) that divides the dividing line CL into eight equal parts is determined.
(Iii ′) At each point CP, in the 100 μm × 100 μm region, the orientation vector (the highest frequency direction) of the easy axis of magnetization is measured by the EBSD method.
(IV ′) The orientation vectors at all points CP are compared, and when the maximum angle difference is 20 ° or more, it is determined that the cross section is a specific cross section and has a non-parallel alignment region.

  With such a method, parallel orientation / non-parallel orientation in the sintered magnet can be determined.

  The type of motor to which the present invention is applied is not particularly limited. The motor may be, for example, a surface magnet type motor (SPM motor), a magnet embedded type motor (IPM motor), or a linear motor.

  Among them, the SPM motor has a structure in which a sintered magnet is installed on the surface of the rotor as shown in FIG. 7 among the rotary motors. Further, the IPM motor has a structure in which a sintered magnet is embedded in the rotor of the rotary motor. Further, the linear motor has a configuration capable of linear movement.

  FIG. 13 schematically shows a cross section perpendicular to the axial direction of the IPM motor. Further, FIG. 14 schematically shows a cross section parallel to the moving direction of the linear motor.

  As shown in FIG. 13, the IPM motor 401 has a rotor 412 rotatably installed around a shaft 410, and a stator 414 surrounding the rotor 412. The stator 414 is provided with a coil 418 having a predetermined number of turns at a predetermined position.

  As can be seen from FIG. 13, the IPM motor 401 is significantly different from the SPM motor in that the sintered magnet 420 is embedded inside the rotor 412.

  In FIG. 13, the rotor 412 has four sintered magnets 420. However, the number of the sintered magnets 420 included in the rotor 412 is not particularly limited as long as it is plural. For example, the rotor 412 may have an even number of sintered magnets 420.

  On the other hand, as shown in FIG. 14, the linear motor 451 has a configuration capable of linear movement.

  Specifically, the linear motor 451 includes a mover 453 and a stator 455. The mover 453 includes a yoke 467 and a plurality of coils 468. The stator 455 has a base 460 and a plurality of sintered magnets 470 arranged on the base 460.

  Among the various motors, in the SPM motor and the linear motor, the cogging torque can be suppressed more significantly by applying the embodiment of the present invention. This is because in the SPM motor and the linear motor, the magnetic flux generated from the sintered magnet is not influenced by the electromagnetic steel plate of the rotor and is linked to the stator.

(Motor group according to an embodiment of the present invention)
Next, another embodiment of the present invention will be described with reference to FIG.

  FIG. 15 schematically shows a motor group according to an embodiment of the present invention.

  As shown in FIG. 15, a motor group (hereinafter, referred to as “third device”) 300 according to an embodiment of the present invention includes a plurality of motors 301 of the same type.

  For example, in the example shown in FIG. 15, the third device 300 includes a total of 10 motors 301 (301A, 301B, ..., 301J).

  The number of motors 301 included in the third device 300 is not particularly limited as long as it is 2 or more.

  Each of the motors 301A to 301J has one sintered magnet (which is difficult to see from FIG. 15).

  The form of the sintered magnet included in each of the motors 301A to 301J is not particularly limited, but the sintered magnet is, for example, the ring-shaped sintered magnet 220 as shown in FIGS. 8 and 9 described above. Is also good.

  In addition, in a normal case, the specific cross section of each sintered magnet is a surface parallel to the moving direction (rotational surface) of each of the motors 301A to 301J.

Here, the sintered magnet included in each of the motors 301A to 301J has the following formula (1) when the surface magnetic flux density is measured over the measurement line in the approximate center in the width direction of the first main surface.

Deviation variation between magnets P [%] =
(Σ _total [mT] / A _total [mT]) × 100 (1) Expression

The deviation variation P between magnets represented by is less than 4%.

  As described above, the “measurement line” means a measurement locus over the first main surface along a direction parallel to the specific cross section.

  Therefore, when the sintered magnet included in each of the motors 301A to 301J is the above-mentioned sintered magnet 220, the measurement line is a plane parallel to the XZ plane at approximately the center in the width direction of the outer side surface 236 of the sintered magnet 220. Along the outer circumference of the sintered magnet 220 (accurately, the outer circumference is 1 mm away from the outer surface 236).

The total average surface magnetic flux density A _total [mT] and the total standard deviation σ _total [mT] are as defined above.

  As described above, the variation deviation P [%] between magnets represented by the equation (1) can be used as an index representing the variation in the magnetic characteristics of each sintered magnet. That is, it can be said that the smaller the P value, the smaller the variation in characteristics between the used sintered magnets.

  Therefore, in a motor group in which each of the motors 301A to 301J includes such a sintered magnet, it becomes possible to significantly suppress vibration and noise.

(Multiple Motor Products According to One Embodiment of the Present Invention)
Next, another embodiment of the present invention will be described.

In another embodiment of the invention,
The same multiple motor products on the market,
There are over 30 motor products,
Each motor product contains one or more magnets,
Each magnet has a void fraction of 7% or less,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

A plurality of motor products having a deviation variation P between magnets of 4% or less are provided.

  In the present application, whether or not a plurality of motor products are “identical” is basically determined by the model number attached to each motor product or its package.

  That is, the model number of the motor product is a unique label determined by the manufacturer for distinguishing the various motor products, and generally, if the same model number is attached, it is recognized that they are the same motor product. You can

  However, a phenomenon called demagnetization often occurs in the motor. Due to this demagnetization, the surface magnetic flux density of the magnet may change even if the model numbers are the same. Therefore, in the present application, even if the model numbers are the same, the induced voltage constant of each motor product is measured and the matching of the values is confirmed.

  If the value of the induced voltage constant measured by the same measuring device is within ± 3%, those motor products are judged to be identical to each other. The induced voltage constant of a motor product is determined by the induced voltage effective value / rotational speed in the case of a rotary motor and the induced voltage effective value / moving speed in the case of a linear motor.

  On the other hand, there are often cases where the model number of the motor product is unknown, such as when the motor product is already incorporated in the drive device. In such a case, whether or not a plurality of motor products are “identical” is determined as follows for each type of motor product.

(When the motor product is a rotary motor)
When the motor product is a rotary motor, it is determined whether or not each motor product is the same by evaluating the following items for each product.

  The rotary motor is roughly divided into two parts, a stator and a rotor. Further, the rotary motor has a structure in which the magnet is arranged on the rotor and a structure in which the magnet is arranged on the stator side. In the following description, in order to make the expression applicable to any of the configurations, the one in which the magnet is arranged is referred to as a field, and the one in which the coil is arranged is referred to as an armature.

[motor]
・ Full length LA of motor products
The total length LA represents the maximum dimension of the motor product in the axial direction. However, the dimensions are excluded from the movable portion whose shape is changed (terminal lines for transmitting electric energy / signal, etc.).
-Induced voltage constant / number of poles The number of poles can be obtained by reading the cycle of the induced voltage waveform with an oscilloscope and doubling the number of cycles per motor shaft rotation.

[Armature]
・ Number of slots MS
The number of slots MS is defined as the number of slots into which the coil is inserted. However, measurement is not required for coreless motors and slotless motors.
・ Diameter DS at the position where the distance to the surface of the armature facing the field is the shortest
The diameter DS is obtained by doubling the length of a line segment that connects the center of the motor shaft and the position of the armature projecting to the most field side when the armature is viewed from the motor axis direction. ..
・ Teeth width WT (WT1, WT2)
The tooth width WT means a linear distance between adjacent slots. In addition, normally, the distance changes between the outer peripheral side and the inner peripheral side of the slot. Therefore, the straight line distance between the adjacent slots on the outer peripheral side of the slot is defined as WT1, and the straight line distance between the adjacent slots on the inner peripheral side of the slot is defined as WT2. However, measurement is not required for coreless motors and slotless motors.
・ Total number of coils NC
-Presence or absence of pseudo groove A pseudo groove means a notched groove existing on the field facing surface of the armature. However, measurement is not required for coreless motors and slotless motors.

[Field]
・ Number of magnets ・ Length of magnet in the motor axis direction LM
· Diameter DR at the position where the distance to the surface of the field facing the armature is the shortest
The diameter DR is obtained by doubling the length of a line segment that connects the center of the motor shaft and the position of the field most protruding toward the armature when the field magnet is viewed from the motor axis direction. ..

  16 to 19 schematically show, as an example, some of the evaluation items in each type of motor product.

  FIG. 16 shows a cross section of an inner rotor type rotary motor in which a magnet rotates. FIG. 17 shows a cross section of an outer rotor type rotary motor in which a coil rotates. FIG. 18 shows a cross section of an outer rotor type rotary motor in which a magnet rotates. FIG. 19 shows a cross section of an inner rotor type rotary motor in which a coil rotates.

  In these figures, the reference numeral GM represents a pseudo groove.

(When the motor product is a linear motor)
When the motor product is a linear motor, it is determined whether or not each motor product is the same by evaluating the following items for each product.

  The linear motor is roughly divided into two parts, a mover and a stator. Further, the linear motor has a structure in which the magnet is arranged in the mover and a structure in which the magnet is arranged in the stator. In the following description, in order to make the expression applicable to any of the configurations, the one in which the magnet is arranged is referred to as a field, and the one in which the coil is arranged is referred to as an armature.

[motor]
・ Full length LA of motor products
The total length LA represents the maximum size of the armature in the direction perpendicular to the moving direction of the motor product and parallel to the facing surface between the armature and the field. However, the dimensions are excluded from the movable portion whose shape is changed (terminal lines for transmitting electric energy / signal, etc.).
・ Induced voltage constant [armature]
・ Number of slots MS
The number of slots MS is defined as the total number of slots in the movable direction that completely cover the entire length of the mover in the movable direction. However, measurement is not required for coreless motors and slotless motors.
・ Pitch PA between coils
The pitch PA between the coils is a coil in one bundle of coils forming a ring, with the center of the distance between the coils in the movable direction as a starting point, and a coil of one bundle of adjacent coils forming another ring. It refers to the distance dimension between two points when the middle point is the end point. However, if there are a plurality of identical measurement points in a range that covers the entire length of the movable element in the movable direction in the movable direction, all of them are measured and the average value is taken.
・ Total number of coils NC
The total number NC of coils is defined as the total number of coils within a range that completely covers the entire length in the movable direction of the mover in the movable direction.

[Field]
-Number of magnets The number of magnets shall be the number of magnets that completely cover the entire length of the mover in the moving direction.
・ Magnet length LM
The magnet length LM represents the magnet size in the direction perpendicular to the movable direction and parallel to the facing surface of the armature and the field. However, in the movable direction, if there are a plurality of magnets within a range that completely covers the entire length of the movable element in the movable direction, all the magnets are measured and the average value thereof is taken.
・ Pitch PB between magnets
The pitch PB between the magnets refers to the distance dimension between two points when the center of the width dimension of one magnet in the movable direction is the starting point and the center of the width of one adjacent magnet is the ending point. However, if there are a plurality of identical measurement points in a range that covers the entire length of the movable element in the movable direction in the movable direction, all of them are measured and the average value is taken.

  20 to 23 schematically show (part of) the above evaluation items in each type of linear motor product as an example.

  FIG. 20 shows a cross section of a moving coil type linear motor with a core. FIG. 21 shows a cross section of a moving magnet type linear motor with a core. FIG. 22 shows a cross section of a coreless moving coil type linear motor. FIG. 23 shows a cross section of a coreless moving magnet type linear motor.

  As described above, in each motor product, these items are evaluated, and if all the items match, it is determined that each motor product is the same.

  However, among the above items, the total length LA of the motor product, the armature diameter DS, the tooth widths WT1 and WT2, the magnet axial length LM, the field diameter DR, the coil pitch, and the magnet length LM. , And the pitch between the magnets includes a dimensional error.

  Therefore, these items are judged to be in agreement with each other if they are within the tolerance range (tolerance class: coarse grade) according to JIS B 0405.

  Further, the induced voltage constants are determined to be in agreement with each other if the values measured by the same measuring device are within ± 3%.

(Application example)
The motor and the motor group according to the embodiment of the present invention can be applied to various drive devices and the like. The drive device may be, for example, a linear motor, a rotary electric motor, a robot having multiple joints, or the like.

  The present invention can be applied not only to general drive devices such as rotary electric motors and linear motors, but also to magnetic application products using magnets, such as galvano-scanner actuators and magnetic refrigeration devices.

(Sintered magnet manufacturing method)
Next, with reference to FIG. 24, an example of a method for manufacturing a sintered magnet having the above-described features will be described.

  FIG. 24 schematically shows the flow of the method for manufacturing a sintered magnet.

As shown in FIG. 24, the method for manufacturing a sintered magnet is
(1) a step of finely pulverizing a raw material alloy for magnets to obtain magnet material particles (step S110),
(2) a step of forming a compact containing magnet material particles (step S120),
(3) a step of applying a part of an annular magnetic field to the compact to orient the easy axis of magnetization of the magnet material particles to polar anisotropy (step S130),
(4) a step of calcining the molded body to obtain a calcined body (step S140),
(5) A step of sintering the calcined body under pressure to obtain a sintered body (step S150),
(6) A step of magnetizing the sintered body (step S160),
Have.

  Hereinafter, each step will be described. In the following description, the manufacturing method of the sintered magnet 120 will be described as an example.

(Step S110)
First, the raw material alloy for a magnet is finely pulverized to form magnet material particles.

  The raw material alloy for magnets is, for example, a neodymium-iron-boron-based alloy. The fine pulverization process may be carried out by, for example, a jet mill pulverizer. The center particle size of the magnet material particles after the fine pulverization treatment is, for example, 1 μm to 5 μm.

(Step S120)
Next, the obtained magnet material particles are mixed with a polymer resin to form a kneaded product.

  As the polymer resin, for example, a depolymerizable polymer may be used. Examples of such a polymer include polyisobutylene (PIB) which is a polymer of isobutylene, polyisoprene (isoprene rubber, IR) which is a polymer of isoprene, polypropylene, and poly (α-methylstyrene) obtained by polymerizing α-methylstyrene. Styrene), polyethylene, polybutadiene (butadiene rubber, BR) which is a polymer of 1,3-butadiene, polystyrene which is a polymer of styrene, and styrene-isoprene block copolymer (SIS) which is a copolymer of styrene and isoprene. Butyl rubber (IIR) which is a copolymer of isobutylene and isoprene, styrene-butadiene block copolymer (SBS) which is a copolymer of styrene and butadiene, and styrene-ethylene- which is a copolymer of styrene and ethylene and butadiene. Butadiene-styrene copolymer Polymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS) which is a copolymer of styrene, ethylene and propylene, ethylene-propylene copolymer (EPM) which is a copolymer of ethylene and propylene, ethylene EPDM prepared by copolymerizing a diene monomer with propylene, 2-methyl-1-pentene polymer resin which is a polymer of 2-methyl-1-pentene, and 2-methyl- which is a polymer of 2-methyl-1-butene. 1-butene polymerization resin etc. are mentioned.

  The polymer used as the polymer resin may contain a small amount of a polymer or copolymer of a monomer containing an oxygen atom and / or a nitrogen atom (for example, polybutyl methacrylate or polymethyl methacrylate). However, a polymer containing no oxygen atom and nitrogen atom is preferable.

  The polymer resin is added so that the ratio of the polymer resin to the total amount of the magnet material particles and the polymer resin (referred to as “polymer resin mixed amount”) is 1 wt% to 20 wt%, for example. The mixing amount of the polymer resin is preferably 2 wt% to 15 wt%, more preferably 2 wt% to 10 wt%, and further preferably 3 wt% to 6 wt%.

  Next, the obtained kneaded material is molded to form a molded body.

(Step S130)
Next, a part of the annular magnetic field is applied to the molded body. As a result, the easy axis of magnetization of the magnet material particles in the molded body is oriented in polar anisotropy.

  In this step, a pulsed magnetic field generator including a multilayer coil and a high capacity capacitor is used. The polar anisotropic orientation can be realized by instantaneously flowing a current stored in a large-capacity capacitor through a multilayer coil and applying a magnetic field in a direction parallel to a specific cross section. The maximum current at this time is, for example, 8 kA to 16 kA, and the pulse width is, for example, 0.3 msec to 10 msec. The annular pulse magnetic field may be applied multiple times.

Further, the step of orienting with polar anisotropy is performed at a temperature at which a melt viscosity of a mixture of a mixture of magnet material particles and a polymer resin at a pulse magnetic field is 900 Pa · s or less, and more preferably Is 700 Pa · s or less, particularly preferably 300 Pa · s or less. When it is 300 Pa · s or less, the orientation degree can be 93% or more even if the magnetic field is applied once. Here, the melt viscosity was measured at a shear rate of 243 s ⁻¹ and a capillary length L / capillary inner diameter D = 1/10. The applied pulse magnetic field strength is preferably 2T or more, more preferably 3T or more. By performing the orientation with the magnetic field strength, the degree of orientation can be increased even with a mixture.

(Step S140)
Next, the molded body is pre-baked to remove the polymer resin component contained in the molded body.

  The calcination treatment is carried out, for example, by heating the molded body to 400 ° C to 600 ° C in a reducing atmosphere. The reducing atmosphere may contain hydrogen.

  After the calcination treatment, a calcinated body is obtained.

(Step S150)
Next, the calcined body is sintered to form a sintered body. The sintering process is performed in a state where the calcined body is pressurized.

  The pressure applied to the calcined body is, for example, 3 MPa to 20 MPa. The firing temperature is, for example, in the range of 700 ° C to 1000 ° C. The direction of the pressure applied to the calcined body is a direction perpendicular to the plane where a specific cross section will be obtained later. For example, in the sintered magnet 120 shown in FIG. 2, the pressure application direction is the Y direction.

  For the sintering treatment, for example, a hot press sintering method, SPS sintering or the like may be used. According to these methods, the polar anisotropic orientation of the magnet material particles obtained in the above-mentioned step can be maintained even after sintering.

(Step S160)
Next, the obtained sintered body is magnetized.

  In this magnetizing process, the same device as that used in step S130 can be used.

  Thereby, a magnet such as the sintered magnet 120 can be manufactured.

  The manufacturing method of the sintered magnet 120 having a substantially rectangular parallelepiped shape has been described above as an example. However, it is obvious to those skilled in the art that the above manufacturing method can be applied to the manufacturing of the substantially ring-shaped sintered magnet 220.

  When the ring-shaped calcined body is sintered in step S150, pressure sintering is particularly preferable.

  FIG. 25 schematically shows a configuration of a jig that can be used for pressure sintering of a ring-shaped calcined body.

  As shown in FIG. 25, this jig 900 includes a central mold 910, an upper pin 920, a lower pin 930, and a center rod 940. The center mold 910 is made of graphite, and the upper pin 920, the lower pin 930 and the center rod 940 are made of stainless steel.

  When performing the pressure sintering process using this jig 900, first, the ring-shaped calcined body 950 is placed inside the central mold 910 with the center rod 940 penetrated.

  Next, the entire jig 900 is heated to a high temperature. The heating temperature is, for example, in the range of 900 ° C to 1050 ° C.

  After the calcined body 950 has reached a predetermined temperature, the calcined body 950 is pressure-sintered by pushing down the upper pin 920 with a predetermined pressure.

  In addition, when using this jig 900, it is preferable to apply a release material in advance to the part of the jig 900 that contacts the calcined body 950. This makes it easy to take out the sintered magnet after the treatment from the jig 900.

  In particular, the mold release material preferably has a two-layer structure of a first mold release material and a second mold release material in the order of increasing distance from the calcined body 950.

  The first release material is used to enhance the adhesion between the second release material and the constituent members of the jig 900. The second release material is used to prevent the calcined body 950 from sticking to the member of the jig 900.

  The first release material contains boron nitride particles and a resin component. The first release material may further include alumina particles. The resin component is added in the range of 15% to 25% with respect to the total weight of the first release material. The resin component is selected from those having a thermal decomposition start temperature of 180 ° C. or higher and 200 ° C. or lower and a thermal decomposition end temperature of 250 ° C. or lower. The first release material has a shear strength of 10 MPa or more at room temperature.

  The second release material contains boron nitride particles and a resin component. The resin component is added in the range of 2% to 10% with respect to the total weight of the second release material. The resin component is selected from those having a thermal decomposition start temperature of 250 ° C. or higher and a thermal decomposition end temperature of 400 ° C. or lower. The second release material has a shear strength of 0.5 MPa or less at room temperature.

The amount of the resin component and the thermal decomposition temperature of the resin component can be measured by using Discovery TGA (manufactured by TA Instruments). Specifically, the following analytical conditions apply in the absence of volatile solvents in the release material:

Sample amount: about 10mg
Atmospheric gas: Air container: Platinum container temperature program: Heating from room temperature to 1000 ° C Heating rate: 10 ° C / min

The decomposition start temperature and the decomposition end temperature are calculated with reference to JIS K7120.

  Specifically, the temperature at the intersection of the baseline after the start of measurement and the maximum tangent line of the TG curve is set as the decomposition start temperature, and the temperature at the intersection of the maximum slope tangent line of the TG curve and the tangent line of the weight reduction end region is set as the decomposition end temperature. did. Further, the amount of residue at 750 ° C. was taken as ash, and the weight reduction rate was taken as the amount of resin component.

Further, the release material shear strength device can be measured by using SAICAS DN-20 type (manufactured by Daipla Wintes). Specifically, the following analytical conditions apply in the absence of volatile solvents in the release material:

Blade width: 1 mm (single crystal diamond)
Rake angle; 10 °
Horizontal speed: 10 μm / sec
Vertical speed: 0.5 μm / sec

Under the above conditions, diagonal cutting was performed from the sample surface, and the shear strength and the peel strength were calculated from the obtained horizontal load / displacement curves by the following formulas:

Shear strength (Pa) = horizontal load (kN) / (2 × shear cross-sectional area (m ² ) × cotφ)

Here, φ is a shear angle (45 °). W is the blade width (m), d is the vertical displacement (m), and the shear cross-sectional area (m ² ) is W × d.

  When such a release material having a two-layer structure is used, sliding resistance at the time of pressure sintering processing is lowered, and it becomes possible to sinter the calcined body 950 without causing cracks or the like. Further, due to the reduction of the sliding resistance, the disorder of the orientation of the calcined body 950 can be suppressed. As a result, the variation among the obtained sintered magnets can be further reduced.

  Further, the use of the above-mentioned two-layer structure release material reduces the possibility that the calcined body 950 is contaminated with impurities. Therefore, the factor that hinders sintering is eliminated, and insufficient sintering can be avoided.

  As a result, the void ratio of the obtained sintered magnet can be significantly reduced.

  It should be noted that such a pressure sintering apparatus and method can be applied to a substantially rectangular parallelepiped calcined body. However, in this case, the jig 900 that does not have the center rod 940 shown in FIG. 25 is used.

  Next, examples of the present invention will be described.

(Evaluation of deviation P between magnets)
The deviation variation P between magnets was evaluated using the sintered magnet manufactured by the following method.

(Example 1)
A sintered magnet was manufactured by the manufacturing method described above.

  First, Nd-Fe-B based alloy (Nd: 25.25 wt%, Pr: 6.75 wt%, B: 1.01 wt%, Ga: 0.13 wt%, Nb: 0.2 wt%, Co: 2.0 wt. %, Cu: 0.13 wt%, Al: 0.1 wt%, balance Fe, and other unavoidable impurities) were pulverized to form magnet material particles. A jet mill grinding device was used for the grinding process. The center particle diameter of the obtained magnet material particles was about 3 μm.

  Next, the obtained magnet material particles were mixed with styrene / butadiene block copolymer (SBS resin) and 1-octadecine and 1-octadecene as oil components to prepare a kneaded product. The amount of the polymer resin mixed was 4 parts by weight with respect to 100 parts by weight of the magnetic material particles, 1-octadecine was 1.5 parts by weight, and 1-octadecene was 4.5 parts by weight. Thereafter, the kneaded product was filled into a mold having a size of 21.2 mm in length × 32 mm in width × 4.3 mm in thickness and molded to prepare a molded body.

  Next, a part of the annular magnetic field was applied to the molded body by the method described above. The annular magnetic field was a pulse magnetic field generated by a pulse current. The pulse current was generated by applying a charging voltage of 1300 V to a capacitor (capacity 1000 μF) connected to the coil and discharging this capacitor. The pulse width of the pulse current was 0.7 ms, and the pulse current was 12.2 kA. The temperature of the molded body after applying the pulsed magnetic field was 120 ° C.

  As a result, the easy axis of magnetization of the magnet material particles contained in the molded body was oriented in polar anisotropy, and the plane represented by the length and the thickness became the specific cross section.

  Next, the compact was calcined in a pressurized hydrogen atmosphere of 0.8 MPa at 500 ° C. to obtain a calcined body.

  Next, the obtained calcined body was filled in a graphite mold. In addition, the calcinated body was sintered by heating the mold to 1000 ° C. while being pressurized at 10 MPa. As a result, a sintered body having a length of 21.2 mm, a width of 16 mm and a thickness of 4.3 mm was formed. After that, grinding was performed to obtain dimensions of 20 mm in length, 15 mm in width, and 4 mm in thickness.

  Next, this sintered body was magnetized using the above-mentioned annular magnetic field until the maximum magnetic flux density was almost saturated.

  Through the above steps, 10 sintered magnets (hereinafter referred to as "lot A") were manufactured.

  FIG. 26 schematically shows the shape of the obtained sintered magnet.

  As shown in FIG. 26, the sintered magnet 520 has a first main surface 530 (first surface) and a specific cross section 560. In FIG. 26, the magnetization direction in the specific cross section 560 is schematically shown.

(Evaluation)
The surface magnetic flux density was measured using each sintered magnet included in the lot A.

  A three-dimensional magnetic field vector distribution measuring device (MTX-5R: manufactured by IMS Inc.) was used for the measurement. As shown in FIG. 26, the measurement was performed at 0.004 mm intervals along the measurement line in a horizontal plane 1 mm above the first main surface 530 of the sintered magnet 520. The measurement line passes through the center of the sintered magnet 520 in the width (Y) direction and is parallel to the length (X) direction.

  The measurement was carried out with the sintered magnet fixed using a non-magnetic material so as not to affect the surface magnetic flux density. The measured surface magnetic flux density is a measurement of the component in the direction normal to the locus of the measurement line.

  In FIG. 27, the measurement results obtained with 10 sintered magnets are shown together.

  In FIG. 27, the horizontal axis represents each position on the measurement line, and the 0 point corresponds to the center of the sintered magnet 520 in the length (X) direction.

  It can be seen from FIG. 27 that the magnets included in the lot A have a small difference in surface magnetic flux density characteristics.

  From the obtained results, the deviation variation P between magnets was calculated by using the above-mentioned formula (1). As a result, the deviation variation P between magnets was about 3.3%.

(Example 2)
Ten sintered magnets (hereinafter referred to as "lot B") were manufactured by the same method as in Example 1, and the characteristics of each sintered magnet were evaluated.

  In FIG. 28, the measurement results obtained for 10 sintered magnets included in lot B are shown together.

  From FIG. 28, it is understood that the magnets included in the lot B have a small difference in surface magnetic flux density characteristics.

  From the obtained results, the deviation variation P between magnets was calculated by using the above-mentioned formula (1). As a result, the deviation variation P between magnets was about 3.5%.

(Example 3)
Ten sintered magnets (hereinafter referred to as “lot C”) were manufactured by the same method as in Example 1, and the characteristics of each sintered magnet were evaluated.

  In FIG. 29, the measurement results obtained for the ten sintered magnets included in lot C are shown together.

  From FIG. 29, it is understood that the magnets included in the lot C have a small difference in surface magnetic flux density characteristics.

  From the obtained results, the deviation variation P between magnets was calculated by using the above-mentioned formula (1). As a result, the deviation variation P between the magnets was about 2.6%.

(Example 4)
Ten sintered magnets (hereinafter referred to as “lot D”) were manufactured by the same method as in Example 1, and the characteristics of each sintered magnet were evaluated.

  FIG. 30 collectively shows the measurement results obtained from the ten sintered magnets included in Lot D.

  From FIG. 30, it can be seen that the magnets included in the lot D have a small difference in surface magnetic flux density characteristics.

  From the obtained results, the deviation variation P between magnets was calculated by using the above-mentioned formula (1). As a result, the deviation variation P between magnets was about 2.5%.

(Example 5)
A sintered magnet was manufactured by the method described below.

  First, Nd-Fe-B based alloy (Nd: 23.45 wt%, Pr: 6.75 wt%, Dy: 1.80 wt% B: 1.01 wt%, Ga: 0.13 wt%, Nb: 0.2 wt%. , Co: 2.0 wt%, Cu: 0.13 wt%, Al: 0.1 wt%, balance Fe and other unavoidable impurities) were pulverized to form magnet material particles. A jet mill grinding device was used for the grinding process. The center particle diameter of the obtained magnet material particles was about 3 μm.

  Next, the obtained magnet material particles were mixed with styrene / butadiene block copolymer (SBS resin) and 1-octadecine and 1-octadecene as oil components to prepare a kneaded product. The amount of the polymer resin mixed was 4 parts by weight with respect to 100 parts by weight of the magnetic material particles, 1-octadecine was 1.5 parts by weight, and 1-octadecene was 4.5 parts by weight. Then, the kneaded product was filled into a mold having an outer diameter of 29.8 mm × an inner diameter of 25.2 mm × a width (axial length) of 30 mm to be molded to prepare a ring-shaped molded body.

  Next, a part of the annular magnetic field was applied to the molded body by the method described above. The annular magnetic field was a pulse magnetic field generated by a pulse current. The pulse current was generated by applying a charging voltage of 2550 V to a capacitor (capacity 1000 μF) connected to the coil and discharging this capacitor. The pulse width of the pulse current was 0.7 ms, and the pulse current was 11.9 kA. The temperature of the molded body after applying the pulsed magnetic field was 120 ° C.

  The coil was installed outside the ring-shaped compact so as to be parallel to the axial direction.

  As a result, the easy axis of magnetization of the magnet material particles contained in the molded body was oriented in polar anisotropy. The molded body was oriented in polar anisotropy so as to have eight magnetic poles on the outer diameter side. The specific cross section of the molded body is a cross section perpendicular to the axial direction.

  Next, the compact was calcined in a pressurized hydrogen atmosphere of 0.8 MPa at 500 ° C. to obtain a calcined body.

  Next, using the jig 900 shown in FIG. 25, the obtained calcined body was subjected to pressure sintering treatment.

  First, the mold release material was spray-coated on the central mold 910, the upper pin 920, the lower pin 930, and the center rod 940 at the places where they might come into contact with the calcined body. The release material has a two-layer structure including the first release material and the second release material described above. The mold release material was installed such that the side of the second mold release material was in contact with the calcined body.

  Next, the calcinated body was pressed at a pressure of 10.5 MPa along the axial direction by the upper pin 920 and the lower pin 930. In this state, the jig 900 was heated to 980 ° C. and held for 30 minutes to sinter the calcined body.

  As a result, a ring-shaped sintered body having an outer diameter of 29.8 mm, an inner diameter of 23.8 mm, and an axial length of 15 mm was formed. This sintered body was heat-treated at 1000 ° C. for 7 hours, and then further heat-treated at 480 ° C.

  Next, this sintered body was magnetized using the above-mentioned annular magnetic field until the maximum magnetic flux density was almost saturated.

  Through the above steps, 30 sintered magnets (hereinafter referred to as "lot E") were manufactured.

(Evaluation)
(Difference variation P between magnets)
By the same method as in Example 1, the surface magnetic flux density was measured using each sintered magnet included in Lot E.

  However, each sintered magnet included in the lot E has a ring shape, and the first main surface is an outer peripheral surface. Therefore, a position 1 mm away from the outer peripheral surface of the sintered magnet was set as a measurement line, and the measurement was performed along this measurement line. The measurement interval is 0.04 °.

  From the obtained surface magnetic flux density, the variation variation P between magnets was calculated by the above-mentioned formula (1), and it was P = 3.8%.

(Void rate)
The void ratio was evaluated using each sintered magnet included in the lot E.

  For the measurement of the void rate, a measuring device FINE SAT III (FS200III) (manufactured by Hitachi Power Solutions Co., Ltd.) was used and the measurement was performed as follows.

  First, a sample for measuring void fraction was prepared from a sintered magnet. A ring-shaped sintered magnet is cut in a direction parallel to a specific cross section, and a ring-shaped sample having a width of 4 mm is taken from a substantially central portion along the axial length direction (direction of width W in FIG. 8) of the sintered magnet. did.

  Next, the sample was placed in the measuring device, and the measurement was performed under the following conditions and operating methods.

  As the probe used, 50P6F15 (frequency 50 MHz, focal length 16 mm, working distance 15 mm) was used. The focus of the probe was measured by the reflection method with the sample being aligned with the central portion in the width direction.

  Specifically, the following operations were performed.

  The Z-axis coordinate of the probe is adjusted so that the surface echo is maximized. Next, with the detection intensity gain fixed at 24 Hz, the Z-axis coordinate of the probe is adjusted so that the echo from the bottom surface of the sample becomes maximum. The distance between the probe and the sample was 0.2 mm or more so that the probe and the sample would not come into contact with each other.

  Next, an F gate having a gate width of 200 ns is set at the center of the surface echo and the echo from the bottom of the sample.

  The Z-axis coordinate of the probe is between the Z-axis coordinate where the surface echo is maximum and the probe Z-axis coordinate where the echo from the sample bottom is maximum so that the sample is focused on the center portion in the width direction. Adjusted to height.

  The height (trigger) of the S gate was adjusted so as not to be affected by noise. The measurement was performed every 50 μm pitch, and speed priority was selected as the scanning mode.

  The energy applied to the probe is 50 V, the pulse repetition frequency (PRF) is 10 kHz, the high pass filter is 10 MHz, the low pass filter is 140 MHz, the depth data is the trigger point, and the surface echo detection mode is used. Was (+) (-).

  The image to be displayed was a standard video (Std), and the brightness of the image displayed by the color bar was 6 for High, 0 for Low, and 0 for Bright.

  From the obtained image, the area ratio of voids was calculated using image analysis software (ImageJ). A void having a brightness of 120 or more was identified as a void.

  The outer peripheral surface and the inner peripheral surface of the sample may be affected in various ways in the process of manufacturing the sintered magnet. For this reason, the area ratio was calculated excluding a portion having a depth of 500 μm from the outer peripheral surface of the sample and a portion having a depth of 500 μm from the inner peripheral surface of the sample.

  As a result of the measurement, the average of the 30 void ratios was 3.8%.

  FIG. 31 shows an example of the obtained image. It was found that the sintered magnet contained in lot E had few voids.

(Example 6)
A sintered magnet was manufactured by the method described below.

  First, Nd-Fe-B based alloy (Nd: 23.45 wt%, Pr: 6.75 wt%, Dy: 1.80 wt% B: 1.01 wt%, Ga: 0.13 wt%, Nb: 0.2 wt%. , Co: 2.0 wt%, Cu: 0.13 wt%, Al: 0.1 wt%, balance Fe and other unavoidable impurities) were pulverized to form magnet material particles. A jet mill grinding device was used for the grinding process. The center particle diameter of the obtained magnet material particles was about 3 μm.

  Next, the obtained magnet material particles were mixed with styrene / butadiene block copolymer (SBS resin) and 1-octadecine and 1-octadecene as oil components to prepare a kneaded product. The amount of the polymer resin mixed was 4 parts by weight with respect to 100 parts by weight of the magnetic material particles, 1-octadecine was 1.5 parts by weight, and 1-octadecene was 4.5 parts by weight. Then, the kneaded product was filled into a mold having a size of 21.2 mm in length × 32 mm in width × 4.3 mm in thickness and molded to prepare a molded body.

  Next, a part of the annular magnetic field was applied to the molded body by the method described above. The annular magnetic field was a pulse magnetic field generated by a pulse current. The pulse current was generated by applying a charging voltage of 1650 V to a capacitor (capacity 1000 μF) connected to the coil and discharging this capacitor. The pulse width of the pulse current was 0.7 ms, and the pulse current was 12.5 kA. The temperature of the molded body after applying the pulsed magnetic field was 120 ° C.

  The coil was installed so as to be parallel to the width direction of the rectangular parallelepiped molded body.

  As a result, the easy axis of magnetization of the magnet material particles contained in the molded body was oriented in polar anisotropy. The specific cross section of the molded body is a direction parallel to the plane formed by the length and the thickness.

  Next, the compact was calcined in a pressurized hydrogen atmosphere of 0.8 MPa at 500 ° C. to obtain a calcined body.

  Next, pressure calcining treatment of the obtained calcined body was carried out.

  For the pressure sintering process, the same device as the jig 900 shown in FIG. 25 was used. However, this device does not have a center rod 940 like the jig 900, but is configured with a center mold, an upper pin, and a lower pin.

  Before the pressure-sintering treatment, a mold release material was spray-applied to a portion that might come into contact with the calcined body. The same release material as in Example 5 was used.

  After the calcined body was placed in the central mold, the calcined body was pressed at a pressure of 9.1 MPa along the axial direction by the upper pin and the lower pin. In this state, the calcined body was sintered by heating the apparatus to 980 ° C. and holding it for 5 minutes.

  As a result, a rectangular parallelepiped sintered body having a length of 21.2 mm, a width of 16 mm, and a thickness of 4.3 mm was formed. This sintered body was heat-treated at 1000 ° C. for 7 hours, and then further heat-treated at 480 ° C. After that, grinding was performed to obtain dimensions of 20 mm in length, 15 mm in width, and 4 mm in thickness.

  Next, this sintered body was magnetized using the above-mentioned annular magnetic field until the maximum magnetic flux density was almost saturated.

  Through the above steps, 30 rectangular parallelepiped sintered magnets (hereinafter referred to as “lot F”) were manufactured.

(Evaluation)
(Difference variation P between magnets)
By the same method as in Example 1, the surface magnetic flux density was measured using each sintered magnet included in Lot F. Further, from the obtained results, the deviation variation P between magnets was calculated by using the above-mentioned formula (1).

  As a result, the variation deviation P between magnets of the lot F was 1.9%.

(Void rate)
The void ratio was evaluated by the above-mentioned method using each sintered magnet included in the lot F. As a result, the average void ratio in Lot F was 1.9%.

(Example 11)
The same evaluation as in Example 1 was performed using five commercially available ring-shaped sintered magnets. A 4-pole anisotropic magnet was used as the sintered magnet.

  FIG. 32 schematically shows the shape of the sintered magnet used.

  As shown in FIG. 32, the sintered magnet 620 has a first main surface 630 (outer peripheral surface) and a specific cross section 660 (upper surface). FIG. 32 schematically shows the magnetization direction in the specific cross section 660.

  In the same manner as in Example 1, the surface magnetic flux density was measured along the measurement line at approximately the center in the width (Y) direction of each sintered magnet 620, and the deviation variation P between magnets was calculated from the obtained result. . In addition, in this Example 11, the measurement line was a circumference 1 mm apart from the outer peripheral surface 630 of the sintered magnet 620, and the measurement interval was 0.04 °.

  As a result, the deviation variation P between magnets was about 4.9%. The average void fraction measured by the above method was 8.1%.

  FIG. 33 shows an example of the obtained image. As is clear from FIG. 33, many voids were recognized in the sintered magnet 620.

(Example 12)
The same evaluation as in Example 1 was carried out using three commercially available ring-shaped sintered magnets. A radial anisotropic magnet was used as the sintered magnet.

  FIG. 34 schematically shows the shape of the used sintered magnet.

  As shown in FIG. 34, the sintered magnet 720 has a first main surface 730 (outer peripheral surface) and a specific cross section 760 (upper surface). FIG. 34 schematically shows the magnetization direction in the specific cross section 760. The outer diameter (maximum dimension in the X direction) of the sintered magnet 720 is 43.1 mm, and the thickness (distance between the outer peripheral surface and the inner peripheral surface) is 2.2 mm. The width (dimension in the Y direction) is 39.2 mm.

  In the same manner as in Example 11, the surface magnetic flux density was measured using each sintered magnet 720, and the deviation P between magnets was calculated from the obtained results.

  As a result, the deviation variation P between magnets was about 7.4%.

(Example 13)
The same evaluation as in Example 1 was performed using ten commercially available ring-shaped sintered magnets. A 4-pole polar anisotropic magnet was used as the sintered magnet.

  The shape of the sintered magnet used is the same as in the case of Example 11 described above.

  In the same manner as in Example 11, the surface magnetic flux density was measured using each sintered magnet, and the deviation variation P between magnets was calculated from the obtained result.

  As a result, the deviation variation P between magnets was about 14.3%.

  The average void fraction of the 10 sintered magnets measured by the above method was 7.3%.

  FIG. 35 shows an example of the obtained image. As is clear from FIG. 35, many voids were recognized in the sintered magnet.

(Evaluation by simulation)
Assuming a series of motor groups (third device) as shown in FIG. 15 described above, the effect of variation deviation P between magnets on the cogging torque of the third device was evaluated by simulation.

  The number of motors was 10, and it was assumed that one sintered magnet was attached to each motor. Further, the sintered magnet mounted on each motor was the sintered magnet 220 having the ring-shaped quadrupole anisotropy as shown in FIGS. 8 and 9 described above.

  Specifically, the following simulation was performed.

  First, Δθ, ΔD, ΔG, Δx, and Δy were assumed as factors that affect the variations in the surface magnetic flux density characteristics of the ten sintered magnets.

  Here, Δθ, ΔD, and ΔG are parameters relating to characteristic variations that occur when the magnet powder compact is magnetized.

  Each parameter will be described with reference to FIGS. 36 and 37.

  FIG. 36 schematically shows the device configuration of the magnetizing process used in the simulation. Further, FIG. 37 shows a schematic enlarged view of a portion surrounded by a thick frame in FIG.

  As shown in FIG. 36, the device 800 includes a sleeve 810, a coil 818, and a yoke 870.

  The sleeve 810 functions as a “mold” for installing the magnet powder compact 821. The sleeve 810 is a magnetic ring and has a center equal to the center H of the device 800.

  Four coils 818 are provided around the sleeve 810 at substantially equal intervals (about 90 ° intervals) with the center H as the center of rotation.

  As shown in FIG. 37, an air region 819 exists between the coil 818 and the sleeve 810.

  The yoke 870 is installed so as to surround the sleeve 810 and the coil 818.

  Here, as shown in FIG. 37, the parameter Δθ described above is an angle formed by a horizontal straight line passing through the center H of the device 800 at the time of the magnetization process and a stretching axis M passing through the center H of the left coil 818. Represent

Further, ΔD is, as shown in FIG. 37, when the maximum dimension of the air region 819 existing between the left coil 818 and the sleeve 810 in the direction of the extension axis M of the coil 818 is D,

ΔD = D−D ₀

It is represented by. Here, D ₀ represents the ideal maximum dimension of the air region 819 in the direction of the extension axis M of the coil 818.

Further, ΔG represents a deviation with respect to complete (100%) magnetization of the magnet powder compact due to the magnetizing process. For example, when the ideal magnetic susceptibility is G ₀ ,

ΔG = G ₀ −G

It is represented by. Here, G is the actual magnetic susceptibility.

  In the actual simulation, the variation of the current value flowing in the coil 818 is used as a direct input parameter, and ΔG is a secondary parameter generated by the variation of the current value.

  On the other hand, Δx and Δy are parameters representing the deviation of the center axis of the sintered magnet obtained after magnetization from the center axis of the ideal sintered magnet. That is, Δx represents the deviation of the central axis of the sintered magnet from the ideal sintered magnet in the x direction, and Δy represents the deviation of the central axis of the sintered magnet from the ideal sintered magnet in the y direction.

  These parameters were changed to generate characteristic variations among the 10 sintered magnets. In addition, the variation range of the cogging torque generated in each motor when the value of the variation deviation P between magnets between the 10 sintered magnets is changed between about 1% and about 11% is evaluated by simulation. did.

  Electromagnetic field analysis software (JMAG-Designer: version 16.1.03k) was used for the simulation.

  The sintered magnet was a neodymium magnet.

  FIG. 38 shows the evaluation result of the simulation.

In FIG. 38, the horizontal axis represents the deviation variation P [%] between the magnets. The vertical axis represents the cogging torque width ΔT [mN · m]. The cogging torque width ΔT [mN · m] is the cogging torque value (K _max ) in the motor in which the largest cogging torque occurs and the cogging torque value (K _min in the motor in which the smallest cogging torque occurs in the third device). ) And the difference.

  It can be seen from FIG. 38 that the cogging torque width ΔT in the third device tends to decrease as the variation deviation P between the magnets decreases. In particular, it is understood that the cogging torque width ΔT can be suppressed to about 2.5 mN · m or less when the deviation variation between magnets P ≦ 4%.

  As described above, in the sintered magnet used for the motor, it was confirmed that the cogging torque generated in the series of motors can be significantly suppressed by setting the variation deviation P between the magnets to 4% or less.

(Evaluation by another simulation)
Assuming a plurality of identical motor products, the effect of the deviation variation P between magnets on the cogging torque was evaluated by simulation.

  It is assumed that the number of motor products is 30, and that one sintered magnet is attached to each motor product. The sintered magnet mounted on each motor product was the sintered magnet 220 having the ring-shaped quadrupole anisotropy as shown in FIGS. 8 and 9 described above. Hereinafter, the configuration used for the simulation will be referred to as a “fourth device”.

  The following simulation was carried out.

  First, Δθ, ΔD, ΔG, Δx, and Δy were assumed as factors that affect the variations in the surface magnetic flux density characteristics of the 30 sintered magnets.

  Here, Δθ, ΔD, and ΔG are parameters relating to characteristic variations that occur during the magnetization process for the compound.

  Each parameter will be described with reference to FIGS. 36 and 37 described above.

  As shown in FIG. 36, the device 800 includes a sleeve 810, a coil 818, and a yoke 870.

  The sleeve 810 functions as a “mold” for installing the compound 821. The sleeve 810 is a ring of magnetic material and has a center equal to the center H of the device 800.

  Four coils 818 are provided around the sleeve 810 at substantially equal intervals (about 90 ° intervals) with the center H as the center of rotation.

  As shown in FIG. 37, an air region 819 exists between the coil 818 and the sleeve 810.

  The yoke 870 is installed so as to surround the sleeve 810 and the coil 818.

  Here, as shown in FIG. 37, the parameter Δθ described above is an angle formed by a horizontal straight line passing through the center H of the device 800 at the time of the magnetization process and a stretching axis M passing through the center H of the left coil 818. Represent

Further, ΔD is, as shown in FIG. 37, when the maximum dimension of the air region 819 existing between the coil 818 on the left side and the sleeve 810 in the direction of the extension axis M of the coil 818 is D,

ΔD = D−D ₀

It is represented by. Here, D ₀ represents the ideal maximum dimension of the air region 819 in the direction of the extension axis M of the coil 818.

Further, ΔG represents a deviation with respect to the perfect (100%) magnetization of the sintered magnet due to the magnetization treatment. For example, when the ideal magnetic susceptibility is G ₀ ,

ΔG = G ₀ −G

It is represented by. Here, G is the actual magnetic susceptibility.

  On the other hand, Δx and Δy are parameters representing the deviation of the center axis of the sintered magnet obtained after magnetization from the center axis of the ideal sintered magnet. That is, Δx represents the deviation of the central axis of the sintered magnet from the ideal sintered magnet in the x direction, and Δy represents the deviation of the central axis of the sintered magnet from the ideal sintered magnet in the y direction.

  These parameters were changed to generate characteristic variations among 30 sintered magnets. At that time, a population with a small variation in the surface magnetic flux density and a population with a large variation were created. In addition, the relationship between the magnet variation deviation P among 30 sintered magnets randomly selected from each population and the cogging torque generated in 30 motor products was evaluated by simulation.

The simulation is
Simulation of variations in the orientation of the easy axis with respect to I compound,
II Simulation of variation in magnetizing a sintered magnet, and III Simulation of variation in cogging torque in motor products,
It carried out in the flow of.

  Electromagnetic field analysis software (JMAG-Designer: version 16.1.03k) was used for the simulation. A two-dimensional static analysis was used for the calculation of I and II, and a two-dimensional transient response analysis was used for the calculation of III.

  Hereinafter, each item of I to III will be described in detail.

(Simulation of variation in orientation of easy axis of magnetization with respect to compound)
An example of a simulation of variations in the orientation of the easy axis of magnetization used in the simulation will be described with reference to FIG.

  The compound 821 has an outer circumference of 15 mmφ and a thickness of 5.6 mm (inner circumference 3.8 mmφ). As the compound material, initial magnetization curve (B-H) data measured by using a pulse excitation type magnetic characteristic measuring device or a measuring device such as a B-H curve tracer is assigned.

  The sleeve 810 was carbon steel S45C having an outer circumference of 25 mmφ and an inner circumference of 7.5 mmφ (thickness t5 mm). The yoke 870 had an outer circumference of 100 mmφ and a thickness t of 37.5 mm (inner circumference of 25 mmφ), and the magnetic material was SS400. A coil 818 exists inside the yoke 870. The coil 818 has a width of 11.2 mm in parallel with a horizontal straight line passing through the center H or the extension axis M as a center line, and a horizontal straight line or extension axis M. It has a depth of 20 mm in the direction perpendicular to.

Fillets having a radius of 2.8 mm were formed at the corners of the coil region. The number of turns was set to 52 turns per coil. Further, the air region 819 existing between the coil 818 and the sleeve 810 has a width of 5.1 mm in parallel with the horizontal straight line of the coil 818 or the extension axis M as a center line, and the direction of the horizontal straight line or the extension axis M. The maximum dimension D ₀ at 0.5 is 0.5 mm.

  Using this model, the above-mentioned parameters Δθ and ΔD were changed, and it was assumed that a current of 20 kA was applied to each coil, and the easy axis direction of the compound 821 was determined.

(Simulation of variation in magnetizing a sintered magnet)
Next, using the same model, the compound 821 was replaced with a sintered magnet, and a pattern in the direction of the easy axis of magnetization determined in advance, the initial magnetization curve (B-H) obtained by actual measurement, the magnetic susceptibility, and the recoil ratio were used. By assigning the magnetizing material data determined by the magnetic permeability curve, and performing the magnetizing process by using Δθ and ΔD and the current value flowing through the coil 818 as a variable parameter, the direction of the easy axis of magnetization and the magnetic susceptibility G are determined. Different magnet material data were created.

  Next, an example of surface magnetic flux density calculation used in the simulation will be described with reference to FIG. 9 described above.

  The sintered magnet 220 has an outer circumference of 10.0 mmφ, a width of W25 mm, and a thickness t of 2.25 mm (inner circumference of 5.5 mmφ), and the magnet material data created by the previous magnetizing process is assigned.

  In assigning the magnet material data, the relative positions of the center H of FIG. 36 and the center C of FIG. 9 are changed by changing the parameters of Δx and Δy described above, and the sintered magnet 220 having different surface magnetic flux waveforms is changed. I got the data.

  In the obtained sintered magnet 220, the surface magnetic flux density was measured along the measurement line, and the deviation variation between magnets P was calculated from the result.

(Simulation of cogging torque variation in motor products)
Next, the shape dimensions of the motor product used for the simulation will be described with reference to FIG.

  As shown in FIG. 39, the stator of the motor product has a cylindrical shape with an outer circumference of 21 mmφ, an inner circumference of 10.3 mmφ, and a laminated thickness of 25 mm, and is arranged concentrically with the sintered magnet. In the stator, six slots for installing coils inside and six teeth for winding the coils are alternately arranged at equal angles.

  The depth dimension of the slot is 17 mmφ, and the tooth width in the portion from the slot depth side of the stator toward the center point C has a uniform thickness of 3.1 mm.

  In addition, the teeth are configured such that the width of the tip on the center side is wide, and the gap between the tips of adjacent teeth is arranged such that the angle passing through the motor center point is 14 degrees. The center-side end portion of the tooth thickness 3.1 mm portion is located on the circumference of a diameter of 12.4 mmφ with the motor center coordinates as the center point. The angle at which the side of the tooth thickness 3.1 mm portion spreads in the tooth front end direction from the terminal end on the center side is 137 °.

  Six such tooth shapes are arranged symmetrically in the stator at equal intervals in the circumferential direction.

  The stator was electromagnetic steel plate 50H700, the shaft was carbon steel S45C, and the coil was copper.

  The number of turns of the coil 218 is arbitrary.

  The setting conditions for calculating the cogging torque are as follows.

  The number of analysis steps was 61, and the rotor was set to rotate 1 ° per step. The number of gap divisions was 4 in the radial direction and 720 in the circumferential direction. The number of elements is 34,938 and the number of nodes is 19,294.

  Under this condition, sintered magnets with different surface magnetic flux densities are assigned and calculated, and the difference between the maximum peak point and the minimum peak point of the output cogging torque waveform is registered as the cogging torque value for the motor product. To do.

  By the above calculation, one surface magnetic flux density and one cogging torque value are associated with one sintered magnet.

  A plurality of combinations of the surface magnetic flux density and the cogging torque value were prepared, and 30 combinations were randomly selected from the combinations to calculate the relationship between the deviation variation P [%] between the magnets and the cogging torque.

  FIG. 40 shows the evaluation result of the simulation.

  In FIG. 40, the horizontal axis represents the deviation variation P [%] between the magnets. The vertical axis represents the average of harmonic amplitude ratios.

  Here, the “harmonic amplitude ratio” is one of the parameters obtained by Fourier transforming the cogging torque value in the range of 360 °.

  Specifically, when the cogging torque value is Fourier-transformed, the amplitude is separated into specific harmonic components. Assuming that the motor product type is N pole M slot, there will be amplitude peaks at positions of order M and at the order of the least common multiple of M and N. The former peak is called a stator period component due to variations in magnets. On the other hand, the latter peak is called a cogging fundamental wave due to the structure of the motor product.

  The "harmonic amplitude ratio" on the vertical axis is expressed as the ratio of both peaks, that is, the stator period component / cogging fundamental wave. Therefore, the "average of the harmonic amplitude ratios" is represented by the average of the harmonic amplitude ratios in the target motor product.

  From FIG. 40, it was found that in the fourth device, when the variation deviation P between magnets was 4% or less, the average of the harmonic amplitude ratios was significantly reduced and was suppressed to about 0.8 or less.

(Evaluation by another simulation)
Assuming a plurality of identical motor products, the effect of deviation variation P between magnets on cogging torque was evaluated by simulation.

  However, here, it is assumed that the number of motor products is 30, and that four sintered magnets are attached to each motor product. The sintered magnets mounted on each motor product were segmented sintered magnets obtained by dividing the ring into quarters. Hereinafter, the configuration used for the simulation will be referred to as a “fifth device”.

  The following simulation was carried out.

  First, Δx and Δy were assumed as factors that affect the dispersion of the surface magnetic flux density characteristics of 4 × 30 sintered magnets.

  Here, Δx and Δy are parameters that cause variations in the focal coordinates of the radial orientation. These parameters were changed to cause characteristic variations among 4 × 30 sintered magnets. At that time, a population with a small variation in the surface magnetic flux density and a population with a large variation were created. In addition, the relationship between the magnet variation deviation P among the 4 × 30 sintered magnets randomly selected from each population and the cogging torque generated in 30 motor products was evaluated by simulation. .

  The software and the like used for the simulation are the same as those for the simulation in the device 4 described above.

The simulation is
I Simulation of characteristic variation in sintered magnet, and II Simulation of variation in cogging torque in motor products,
It carried out in the flow of.

  Each will be described below.

(Simulation of characteristic variation in sintered magnet)
An example of calculation of the surface magnetic flux density used in the simulation will be described with reference to FIG.

  As shown in FIG. 41, the sintered magnet used was a segment shape in which a ring having an outer circumference of 19 mmφ and a thickness of t3.5 mm (inner circumference of 12 mmφ) was divided into quarters, and a straight line formed by the X axis and the Y axis In parallel with the above, the magnet portion is removed by 0.4 mm, and the four corners are chamfered at 1 mm square.

  In this magnet model, the center point corresponding to the outer circumference circle or the inner circumference circle of the magnet is set as the origin coordinates (0, 0), and the reference focus coordinates are set at the coordinates (13, 13). That is, it is assumed that the easy axis of magnetization in the magnet is oriented so as to converge to the coordinates (13, 13). By shifting Δx in the X-axis direction and Δy in the Y-axis direction with respect to the reference coordinates, data of the sintered magnet having different focus coordinates is created.

  In the data of each sintered magnet, the surface magnetic flux density is measured along the measurement line, and the deviation P between magnets is calculated from the obtained result. Here, the measurement line in the sintered magnet means a surface on the side facing the focus coordinates as a first main surface, and a Y-axis from the X axis on a concentric circle 1 mm away from the first main surface on the focus coordinate side. It means the range from 0 ° to 90 ° to the axis.

(Simulation of cogging torque variation in motor products)
Next, the shape dimensions of the motor product used for the simulation will be described with reference to FIG.

  As shown in FIG. 42, the stator core of the motor product has a cylindrical shape with an outer circumference of 42 mmφ, an inner circumference of 20.4 mmφ, and a laminated thickness of 23 mm, and is arranged concentrically with the sintered magnet. On the stator core, six slots for installing coils inside and six teeth for winding the coils are alternately arranged at equal angles.

  The depth dimension of the slot is 34 mmφ, and the tooth width in the portion from the slot depth side of the stator toward the center point C has a uniform thickness of 6.2 mm.

  Further, the teeth are configured such that the width of the tip on the center side is wide, and the gap between the tips of adjacent teeth is arranged so that the angle passing through the motor center point is 14 degrees. The center-side end portion of the teeth thickness 6.2 mm portion is located on the circumference of a diameter of 24.8 mmφ with the motor center coordinates as the center point. The angle when the side of the tooth thickness of 6.2 mm spreads in the tooth tip direction with the terminal end on the center side as the base point is 137 °.

  Six such tooth shapes are arranged symmetrically in the stator at equal intervals in the circumferential direction.

  The rotor includes a shaft at the center of the motor product, a sintered magnet on the outer diameter side of the rotor, and a rotor core made of a magnetic material between the shaft and the sintered magnet. The rotor core has an outer circumference of 12 mmφ and an inner circumference of 6 mmφ, and a total of four protrusions having a distance of 9 mm from the motor center are provided so as to fill the gap between the sintered magnets.

  The stator core and the rotor core were electromagnetic steel plates 50A700, the shaft was carbon steel S45C, and the coil was copper. The number of turns of the coil is arbitrary.

  The setting conditions for calculating the cogging torque are as follows.

  The number of analysis steps was 61, and the rotor was set to rotate 1 ° per step. The number of gap divisions was 4 in the radial direction and 720 in the circumferential direction. The number of elements is 43,395 and the number of nodes is 23,218.

  Under this condition, sintered magnet patterns with various different surface magnetic flux densities are assigned to the four sintered magnets of the motor product for calculation, and the maximum peak point and the minimum peak point of the output cogging torque waveform are calculated. The difference is registered as a cogging torque value in the motor product.

  The focal position pattern of the sintered magnet shown in FIG. 41 is a pattern example corresponding to the sintered magnet located in the first quadrant of the sintered magnet in the motor of FIG. Therefore, when the positions of the sintered magnets are different from those in the second quadrant, the third quadrant, and the fourth quadrant, patterns in which the respective coordinates are rotationally moved by 90 ° are assigned.

  By the above calculation, four surface magnetic flux densities (four sintered magnets) and one cogging torque value are associated with one motor product.

  By preparing a plurality of combinations of these four surface magnetic flux densities and cogging torque values, and randomly selecting 30 combinations from among them, 4 × 30 variation deviation P [%] between magnets and 30 The relationship of the cogging torque of the single motor product was calculated.

  FIG. 43 shows the evaluation result of the simulation.

  In FIG. 43, the horizontal axis represents the deviation variation P [%] between the magnets. The vertical axis represents the average of harmonic amplitude ratios.

  From FIG. 43, it was found that in the fifth device, when the variation deviation P between the magnets was 4% or less, the average of the harmonic amplitude ratios was significantly reduced and was suppressed to about 0.8 or less.

  As described above, in the sintered magnet used for the motor product, it is confirmed that the cogging torque and the harmonic amplitude ratio generated in the plurality of motor products can be significantly suppressed by setting the variation deviation P between the magnets to 4% or less. It was

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in the different embodiments Is also included in the technical scope of the present invention.

101 motor 110 shaft 112 rotor 114 stator 118 coil 120 sintered magnet 130 first surface 132 second surface 136 first side surface 137 second side surface 138 third side surface 139 fourth side surface 160 cross section 162 area 201 motor 210 shaft 212 rotor 214 stator 218 coil 220 sintered magnet 230 first surface 232 second surface 236 outer side surface 237 inner side surface 260 cross section 262 region 300 motor group 301 (301A, 301B, ..., 301J) motor 401 IPM motor 410 shaft 412 rotor 414 stator 418 coil 420 sintered magnet 451 linear motor 453 mover 455 stator 467 yoke 468 coil 460 base 470 sintered magnet 520 sintered magnet 530th 1 main surface 560 specific cross section 620 sintered magnet 630 first main surface 660 specific cross section 720 sintered magnet 730 first main surface 760 specific cross section 800 device 810 sleeve 818 coil 819 air region 821 green compact 870 yoke 900 jig 910 Central type 920 Upper pin 930 Lower pin 940 Center rod 950 Calcined body AP cross section CL dividing line CP point

Claims (12)

The same multiple motor products on the market,
There are over 30 motor products,
Each motor product contains one or more magnets,
Each magnet has a void fraction of 7% or less,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

A plurality of motor products having a variation deviation P between magnets represented by 4% or less:
Here, the measurement line, when a cross section in which the non-parallel oriented region is recognized is referred to as a specific cross section, at a substantially center of the first main surface, along a direction parallel to the specific cross section, 1 represents a measurement locus corresponding to the entire main surface, and the measurement line is defined at a spatial position 1 mm above the first main surface,
A _total represents the total average surface magnetic flux density, and when the absolute values of the surface magnetic flux densities at the same measurement positions on the measurement lines in each sintered magnet were averaged, and this was taken as B _ave [mT], the measurement Calculated by summing the average values B _ave [mT] at all measurement positions on the line,
σ _total represents the total standard deviation, and the standard deviation of the surface magnetic flux density at each measurement position used in the calculation of the total average surface magnetic flux density A _total on the measurement line in each sintered magnet is σ [mT]. Then, the standard deviation σ [mT] at all the measurement positions on the measurement line is calculated.   The plurality of motor products of claim 1, wherein each motor product includes a magnet.   The plurality of motor products of claim 1, wherein each motor product includes a plurality of magnets. A motor having a plurality of magnets,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

The deviation variation P between the magnets represented by is 4% or less, the motor:
Here, the measurement line, when a cross section in which the non-parallel oriented region is recognized is referred to as a specific cross section, at a substantially center of the first main surface, along a direction parallel to the specific cross section, 1 represents a measurement locus corresponding to the entire main surface, and the measurement line is defined at a spatial position 1 mm above the first main surface,
A _total represents the total average surface magnetic flux density, and when the absolute values of the surface magnetic flux densities at the same measurement positions on the measurement lines in each sintered magnet were averaged, and this was taken as B _ave [mT], the measurement Calculated by summing the average values B _ave [mT] at all measurement positions on the line,
σ _total represents the total standard deviation, and the standard deviation of the surface magnetic flux density at each measurement position used in the calculation of the total average surface magnetic flux density A _total on the measurement line in each sintered magnet is σ [mT]. Then, the standard deviation σ [mT] at all the measurement positions on the measurement line is calculated.   The motor of claim 4, wherein each magnet has a void fraction of 7% or less.   The motor according to claim 4 or 5, wherein the non-parallel orientation is polar anisotropic orientation or radial orientation.   The motor according to claim 4, wherein the magnet has a substantially rectangular parallelepiped shape or a substantially ring shape. A series of motor groups having a plurality of motors,
Each motor has one magnet
Each magnet is a sintered magnet having non-parallel-oriented regions and has a first main surface with a maximum peak value of surface magnetic flux density,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation deviation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

A motor group in which the deviation variation P between magnets represented by is 4% or less:
Here, the measurement line, when the cross section in which the non-parallel oriented region is recognized is referred to as a specific cross section, in the substantially center of the first main surface, along the direction parallel to the specific cross section, 1 represents a measurement locus corresponding to the entire one main surface, and the measurement line is defined at a spatial position 1 mm above the first main surface,
A _total represents the total average surface magnetic flux density, and when the absolute values of the surface magnetic flux densities at the same measurement positions on the measurement lines of the respective sintered magnets were averaged, and this was taken as B _ave [mT], the measurement was performed. Calculated by summing the average values B _ave [mT] at all measurement positions on the line,
σ _total represents the total standard deviation, and the standard deviation of the surface magnetic flux density at each measurement position used for the calculation of the total average surface magnetic flux density A _total on the measurement line in each sintered magnet is σ [mT]. Then, the standard deviation σ [mT] at all the measurement positions on the measurement line is summed up.   The motor group according to claim 8, wherein each magnet has a void fraction of 7% or less.   A drive device comprising the motor according to any one of claims 4 to 7, or the motor group according to claim 8 or 9.   A plurality of motor products according to any one of claims 1 to 3, taken from the same drive. A magnet group including a plurality of magnets,
Each magnet has a void fraction of 7% or less,
Each magnet is a sintered magnet having non-parallel oriented regions, and has a first main surface where the peak value of the surface magnetic flux density is maximum,
When the surface magnetic flux density is measured across the measurement line on the first main surface of each magnet, the following formula is obtained.

Variation variation between magnets P [%] = (σ _total [mT] / A _total [mT]) × 100

A magnet group in which the deviation variation P between magnets represented by is 4% or less:
Here, the measurement line, when a cross section in which the non-parallel oriented region is recognized is referred to as a specific cross section, at a substantially center of the first main surface, along a direction parallel to the specific cross section, 1 represents a measurement locus corresponding to the entire main surface, and the measurement line is defined at a spatial position 1 mm above the first main surface,
A _total represents the total average surface magnetic flux density, and when the absolute values of the surface magnetic flux densities at the same measurement positions on the measurement lines in each sintered magnet were averaged, and this was taken as B _ave [mT], the measurement Calculated by summing the average values B _ave [mT] at all measurement positions on the line,
σ _total represents the total standard deviation, and the standard deviation of the surface magnetic flux density at each measurement position used in the calculation of the total average surface magnetic flux density A _total on the measurement line in each sintered magnet is σ [mT]. Then, the standard deviation σ [mT] at all the measurement positions on the measurement line is calculated.