JP2000253608A - Brushlfss motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an overall torque in a brushless motor by eliminating the deviation between the peak of Fleming's torque and that of reluctance torque. SOLUTION: A brushless motor has a rotor 1 containing first permanent magnets 3 and slits 1a and a stator 6 which is arranged on the outer periphery of the rotor 1 and in which stator windings 7 are wound around teeth 8 for supplying driving forces to the rotor 1. The rotor l is made of a material having high magnetic permeability and constituted in such a way that the magnetic reluctance of the rotor 1 on a q-axis is set differently from that on a d-axis, with the q-axis being the straight line connecting the center of rotation and outer peripheral surface of the rotor 1 and the d-axis being the straight line which passes the center of rotation electrically perpendicularly to the q-axis. In addition, the centers of the first permanent magnets 3 are positioned in the areas surrounded by the Q- and d-axes on the outer peripheral surface of the rotor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor that uses a reluctance torque in addition to a framing torque, which is a magnet torque, by embedding a permanent magnet in a rotor.

[0002]

2. Description of the Related Art In recent years, environmental issues have become a social topic and energy saving has become an important concern. Particularly in the field of motors, small, high-efficiency, high-output motors have been desired from the viewpoint of energy saving. Under such circumstances, a motor (brushless motor) having a different structure from the conventional motor has appeared.

As such a motor, for example, SPM
(Surface Permanent Magne
t) a motor.

As shown in FIG. 14, for example, the SPM motor includes a rotor 121 formed of a laminated steel plate and a permanent magnet 122 disposed on an outer peripheral surface of the rotor 121.
And a non-magnetic SUS tube 12 arranged on the outer peripheral surface of the permanent magnet 122 to prevent scattering of the rotating permanent magnet 122.
3 and a stator 125 arranged close to the outer peripheral surface of the SUS tube 123.

In the SPM motor having the above configuration, the magnetic field of the permanent magnet 122 and the coil 12 provided on the stator 125
The driving force is transmitted to the outside from the rotating shaft 124 that is the central axis of the rotor 121 by using the framing torque according to the framing law caused by the current flowing through the rotor 6.

As another motor, there is a synchronous reluctance motor. This synchronous reluctance motor includes a rotor composed of laminated steel plates and a stator for transmitting a driving force to the rotor. A plurality of slits are provided inside the rotor such that the central portion is convex on the rotation axis.

The synchronous reluctance motor having the above configuration is a motor utilizing reluctance torque generated by a magnetic resistance difference in a region connecting a rotor outer peripheral point and a center point.

Therefore, the synchronous reluctance motor is suitable for high-efficiency and high-speed rotation because it does not use magnets so that iron loss due to magnet flux does not occur and no induced voltage is generated in the stator coil.

The above-described SPM motor is excellent in mass productivity, but has room for improvement in efficiency. Therefore, a permanent magnet is embedded in the rotor to utilize reluctance torque in addition to framing torque.
PM (Interior Permanent Mag)
net) motors have been proposed.

In the above-described IPM motor, for example, as shown in FIG. 15, a permanent magnet 132 is embedded in a rotor 131 made of an iron core made of a high magnetic permeability material or a laminated silicon steel sheet. The stator 135 is arranged so as to be close to the outer peripheral surface. Note that FIG. 15 shows a half configuration of the IPM motor, and the other half configuration is omitted.

The above-structured IPM motor is a four-pole motor, in which four (two in the figure) permanent magnets 132 are arranged such that the N and S poles are alternately arranged along the circumferential direction.
It is arranged on the surface.

With this configuration, d is a direction connecting the center of the permanent magnet 132 and the center of the rotor 131.
The inductance Ld in the axial direction and the inductance L in the q-axis direction which is a direction rotated by 90 electrical degrees with respect to the d-axis.
A difference occurs between q and q, so that reluctance torque is generated in addition to the framing torque by the permanent magnet 132.

For a description of these relationships, see References (Rotating machines utilizing reluctance torque (Nobuyuki Matsui et al., TE
E Japan, Vol. 114-D, no. 9, '9
According to 4)), the following equation (1) is obtained.

[0014]

(Equation 1)

Here, Pn: the number of pole pairs ψa: linkage flux Ld: d-axis inductance Lq: q-axis inductance id: d-axis current iq: q-axis current

In the SPM motor shown in FIG. 14, since the magnetic permeability of the permanent magnet 122 is substantially equal to the magnetic permeability of the air, the two inductances Ld and Lq in the above equation (1) have substantially the same value. The reluctance torque shown by the second term in the equation does not occur.

However, in the IPM motor shown in FIG. 15, the inductance Ld in the d-axis direction is the direction in which the magnetic flux of the permanent magnet 132 is generated, and the flow of the magnetic flux in the d-axis direction is the same as that of air. Since the magnetic resistance is large, the inductance Ld in the d-axis direction is small. On the other hand, since the inductance Lq in the q-axis direction passes through the iron core of the rotor, the magnetic resistance decreases,
The inductance Lq in the q-axis direction increases. For this reason, a difference is generated between the inductance Ld in the d-axis direction and the inductance Lq in the q-axis direction, and the reluctance torque of the second term of the above equation (1) is generated by flowing the d-axis current id.

From the viewpoint of the magnetic flux vector, the Fleming torque Tm is generated by multiplying the magnetic flux ψa by a current iq in a direction perpendicular to the electrical direction. Similarly, the reluctance torque Tr is generated by the inductance and the current. The magnetic fluxes are generated by multiplying the magnetic fluxes Ld · id and Lq · iq by electric currents id and iq, respectively, which are perpendicular to each other. The sum of these two torques is the total torque Tt.

Incidentally, the total torque Tt changes according to the input current phase. The following equation (2) is an equation that takes this into consideration with respect to the above equation (1).

[0020]

(Equation 2)

Here, Pn: the number of pole pairs ψa: linkage flux Ld: d-axis inductance Lq: q-axis inductance id: d-axis current iq: q-axis current β: current phase ia: current vector size

FIG. 16 is a graph showing the relationship between the fleming torque Tm and the reluctance torque Tr when the current phase β is changed, and the total torque Tt obtained by adding both.

From the graph shown in FIG. 16, it can be seen that the Fleming torque Tm has a maximum value at a current phase of 90 °, becomes smaller as the current phase advances, and becomes 0 at 180 °. Then, since the reluctance torque Tr shows the maximum value at the current phase of 135 °, the total torque Tt obtained by adding the two changes depending on the respective torque ratios, but the maximum value exists around the current phase of 115 °. You can see that it is.

Therefore, it can be seen that the IPM motor that effectively uses the reluctance torque Tr can output a higher torque at the same current than the SPM motor that uses only the framing torque Tm.

However, in order to further increase the efficiency, it is possible to improve the total torque Tt by changing the current phase. However, when each torque alone is viewed, it is not always the maximum value. That is, in the graph shown in FIG. 16, the peak of the framing torque Tm and the peak of the reluctance torque Tr do not overlap at the point of the current phase where the total torque Tt is maximum.

Therefore, a technique taking this point into consideration is disclosed in Japanese Patent Laid-Open No.
-23598 and JP-A-7-143694.

For example, Japanese Patent Application Laid-Open No. 9-23598 discloses that a d-axis inductance Ld and a q-axis inductance Ld are provided by disposing a first permanent magnet having a smaller magnetic flux permeability than a rotor iron core near a rotor cylindrical surface. Even if the difference between the shaft inductances Lq is the same, reducing the d-axis inductance Ld improves the orthogonality between the magnetic flux and the current to improve the efficiency of the motor. Alternatively, it is disclosed that at least one of a large magnet insertion hole for a magnet is provided to reduce negative torque and improve the efficiency of the motor.

Japanese Unexamined Patent Publication No. 143694/1995 discloses that, although it is not an IPM motor, attention is paid to the orthogonality between magnetic flux and current, and a material having high magnetic permeability between a plurality of permanent magnets arranged on the outer periphery of the rotor. With a protruding salient pole
Position the magnet at 45 ° or more and 90 ° with respect to the protruding salient pole.
A technique has been disclosed in which the peaks of the fleming torque and the reluctance torque coincide with each other by being shifted in the rotation direction by an angle smaller than the angle.

[0029]

The above-mentioned synchronous reluctance motor has a high efficiency and a high speed because no magnet loss is used and no iron loss is generated due to the magnet magnetic flux, and no induced voltage is generated in the stator coil. Although it is suitable for rotation, it has a problem that the generated torque is small and the efficiency at low speed is poor as compared with a motor using a normal permanent magnet.

The above publications also have the following problems.

In Japanese Patent Application Laid-Open No. 9-23598, a negative torque is generated by providing at least one of a gap, a notch, or a magnet insertion hole large for a magnet in a portion opposite to the rotating direction of the rotor. The magnetic flux of the magnet is reduced in the part to be made, the magnetic flux contributing to generate a positive torque as a whole is increased, and the positive torque is increased, but the deviation between the peak of the Fleming torque and the peak of the reluctance torque is Not resolved.

Further, it is disclosed that the orthogonality between the current and the magnetic flux is improved by the motor structure. However, even when the d-axis inductance Ld = 0, deviation of each torque peak occurs. Further, a specific structure for Ld = 0 is not specified.

Japanese Patent Application Laid-Open No. 143694/1991 discloses that a peak deviation between a fleming torque and a reluctance torque is eliminated by using a salient pole position in a protruding shape of a rotor and a magnet arrangement. However, this is effective when the rotor structure has salient salient poles, but the magnet position is not limited for other rotor structures without salient salient poles.

Further, in the motor structure disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 143694/1995, the holding of the magnet is not specified.

Usually, when the magnet is arranged on the surface of the rotor, a SUS tube having a low magnetic permeability is used to prevent scattering. The air gap between the rotor and the stator is widened due to the SUS pipe or the like for preventing the scattering, which is one of the causes of the deterioration of the motor performance. Further, as the rotational speed of the motor increases, S
Iron loss (eddy current loss) generated in the US pipe portion increases, and the efficiency is reduced.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to eliminate a deviation between a peak of a fleming torque and a peak of a reluctance torque.
An object of the present invention is to provide a brushless motor capable of improving overall torque.

[0037]

According to a first aspect of the present invention, there is provided a brushless motor, wherein the rotor is disposed close to an outer peripheral surface of the rotor, and a driving force is applied to the rotor. A stator wound with a winding wound around a stator core for supplying, the rotor having a first axis defined by a straight line connecting a rotation axis of the rotor and an outer peripheral surface, and passing through the rotation axis. The first
When a straight line electrically perpendicular to the axis is defined as a second axis, the magnetic resistance of the first region of the rotor through which the first axis passes is different from the magnetic resistance of the second region through which the second axis passes. And a permanent magnet center is disposed in the vicinity of the outer peripheral surface of the rotor on the acute angle side surrounded by the first axis and the second axis.

According to the above configuration, the first rotor in the rotor
When the axis is a reference axis (q-axis) and the second axis is a d-axis orthogonal to the q-axis, the magnetic resistances in the rotor regions (first region and second region) passing through each axis are different. Therefore, the inductance in the q-axis direction related to the magnetoresistance and d
The magnitude of the inductance in the axial direction will be different.

As a result, reluctance torque is generated in addition to the framing torque by the permanent magnet disposed on the rotor, and the total torque is obtained by adding the framing torque and the reluctance torque.

The permanent magnet is arranged in a region surrounded by the first axis and the second axis on the outer peripheral surface of the rotor.
That is, the permanent magnets are arranged in an electrical angle range of 0 ° to 90 ° with respect to the first axis.

By arranging the permanent magnet centers in the electrical angle range of 0 ° to 90 °, the peak position of the fleming torque caused by the permanent magnet and the peak position of the reluctance torque caused by the difference in the magnetic resistance. Can be reduced, and as a result, the total torque can be improved.

That is, by arranging the permanent magnets within the electric angle range and the permanent magnet center at an electric angle of about 45 °, the peak position of the fleming torque and the peak position of the reluctance torque can be substantially reduced. Since they can be matched, the total torque can be greatly improved.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, in addition to the configuration of the first aspect, the rotor includes a rotor parallel to the rotation axis of the rotor and near the center. A plurality of gaps having a shape substantially convex toward the rotation axis and having both ends extending to near the surface of the rotor are formed around the rotation axis, and the gaps are included in the first region. Not
Further, it is characterized by being included in the second region.

According to the above configuration, in addition to the effect of the first aspect, the magnetic permeability of the gap may be considered to be the same as that of air. As a result, the magnetic resistance of the second axis passing through the gap is reduced. It is larger than the magnetic resistance of the first axis that does not pass through the gap. Thus, a difference in magnetic resistance can be easily generated only by providing a gap inside the rotor.

In addition, since the center of the gap is convex toward the rotating shaft of the rotor, and both ends of the gap extend to near the surface of the rotor, the inductance of the first shaft and the second Since the difference from the shaft inductance can be further increased, the reluctance torque can be increased.

A brushless motor according to a third aspect is characterized in that, in order to solve the above-mentioned problem, in addition to the configuration of the second aspect, a permanent magnet is fitted into the gap.

According to the above configuration, in addition to the function of the second aspect, the permanent magnet is fitted in the gap, so that the permanent magnet is disposed inside the rotor. As a result, the equivalent magnet surface area of the rotor increases, and the framing torque can be increased. As a result, the total torque can be increased.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, in addition to any one of the first to third aspects, the permanent magnet near the outer peripheral surface of the rotor has the surface of the stator. Is disposed so as to face the side surface of the winding wound around the stator core.

According to the above construction, in addition to the function of any one of claims 1 to 3, the permanent magnet near the outer peripheral surface of the rotor has a surface wound around the stator core of the stator. By arranging it so as to face the side surface, it is possible to make the peaks of the fleming torque and the reluctance torque substantially coincide with each other by concentrating the magnet magnetic flux in a desired region.

Therefore, the equivalent air gap can be reduced and the leakage flux can be reduced, so that a brushless motor with high torque and high efficiency can be provided.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Regarding each embodiment of the present invention,
This will be described below. In each embodiment, a 4-pole DC brushless motor will be described as the brushless motor. Further, for convenience of explanation, only the half structure is shown without showing the entire structure of the motor.

[Embodiment 1] DC according to the present embodiment
As shown in FIG. 1, the brushless motor is disposed close to a cylindrical rotor 1 and an outer peripheral surface of the rotor 1.
And a stator 6 for supplying a driving force to the rotor 1.

The rotor 1 is formed by punching out a thin laminated body of a high magnetic permeability material into a circular shape, and is formed in a cylindrical shape. The rotor 1 has a gap extending in the axial direction of the rotating shaft 4 of the rotor 1. A plurality of slits 1a are formed around the rotation shaft 4 and a notch 1b is formed at a predetermined position on the outer peripheral surface of the rotor 1.
Are formed corresponding to the slits 1a.

The first permanent magnet 3 is fitted in the notch 1b. In the present embodiment, four first permanent magnets 3 are arranged, and the polarity of each first permanent magnet 3 is magnetized as shown in FIG.
The pairs are arranged such that the polarities are inverted. In FIG. 1, the polarities of the adjacent first permanent magnets 3 are reversed.

The rotational force of the rotor 1 having the above structure is transmitted to the outside by a rotating shaft 4 provided at the center of the rotor 1.

The slit 1a formed inside the rotor 1 is formed in a substantially arc-shaped cross section. The center is formed to be convex toward the rotation shaft 4 of the rotor 1, and both ends of the slit 1a are formed. The portions 1a 'and 1a' have a shape extending to a position close to the outer peripheral surface of the rotor 1. This slit 1a
Has a lower magnetic permeability than the other parts of the rotor 1 because air enters the inside. That is, the slit 1 a has a higher magnetic resistance than the other parts of the rotor 1.

The notch 1b formed on the outer peripheral surface of the rotor 1 has a straight line (first axis) 5 connecting the rotation center of the rotor 1 and the outer peripheral surface as a reference axis (q axis). A straight line (second axis) 9 that passes through the rotation center and is electrically orthogonal to the q axis is d.
As an axis, it is formed within the range on the acute angle side (electrical angle 0 ° to 90 °) between the q axis and the d axis. At this time, the center of the notch 1b passes around 45 ° in electrical angle (22.5 ° in mechanical angle). That is,
The center (permanent magnet center) of the first permanent magnet 3 fitted into the notch 1b also passes through an electrical angle of about 45 °.

In other words, the notch 1b is arranged such that the outer periphery of the first permanent magnet 3 into which the center of the notch 1b is fitted at an electrical angle of about 45 ° with respect to the q axis is partially exposed. It is formed so that.

The q axis is the slit 1 in the rotor 1.
a is set so as to pass through a region where the permeability does not change (first region) without passing through the center a of the slit 1a in the rotor 1, that is, a region where the permeability changes (the first region). (The second area).

Here, the reference axis will be described below with reference to FIG. In FIG. 2, point a indicates an intersection with the q axis in the outer peripheral portion of the rotor 1, point b indicates an intersection with the d axis, and point O indicates a center point of the rotation shaft 4.

At this time, the magnetic resistance between the outer peripheral portion of the rotor 1 and the center of the rotor 1 is considered as follows.

The portion between a and O is constituted by the rotor 1 and the rotating shaft 4 which are made of a laminate of high permeability materials and has a low magnetic resistance. On the other hand, between b and O is constituted by a rotor 1 made of a thin plate laminate of a high magnetic permeability material and an air layer of a slit 1a having a lower magnetic permeability than the rotor 1 described above, and has a large magnetic resistance. Become.

When the magnetic resistance between the outer periphery of the rotor 1 and the center of the rotor 1 is applied to the entire circumference of the rotor 1, the minimum magnetic resistance is between a and O. The axis including the smallest point of the magnetic resistance is defined as a reference axis. However, although the magnetic resistance near the point a is exactly the same, the axis including the point a located at the center between the magnets is taken as the reference axis in consideration of the symmetry of the shape. Also, an axis obtained by rotating the phase by 90 degrees in electrical angle from the q axis, which is the reference axis, is referred to as a d axis.

In this embodiment, the reference axis,
Define the q-axis and d-axis. Note that, in the present embodiment, the d-axis is illustrated as being rotated at a mechanical angle of 45 ° (electrical angle 90 °) with respect to the q-axis.

Next, the stator 6 for supplying a driving force to the rotor 1 will be described.

The stator 6 includes a predetermined number of teeth 8 as stator cores, and a stator winding 7 as a winding is wound between the teeth 8. The winding state of the stator winding 7 is omitted. And
When an alternating current is applied to the stator winding 7, a rotating magnetic flux is generated, and the generated rotating magnetic flux acts on the rotor 1 with a framing torque and a reluctance torque, so that the rotor 1 is driven to rotate. This rotational force is transmitted to the outside by the rotating shaft 4.

The principle of the effect of the DC brushless motor configured as described above will be described.

First, as shown in FIG. 1, by arranging the center of the first permanent magnet 3 between 0 ° and 45 ° in electrical angle from the q axis which is the reference axis, the center of the magnet magnetic flux distribution is also changed. Moving from 0 °. Assuming that the moving amount of the magnetic flux is the magnetic flux shift amount θ (deg), the following expression (3) is derived from the expression (2) shown in the section of the related art.

[0069]

(Equation 3)

On the other hand, when θ = 0 (conventional method), the torque indicates the maximum torque value Tmax when the current phase β is given by the following equations (4) and (5).

[0071]

(Equation 4)

[0072]

(Equation 5)

FIG. 3 is a graph showing the relationship between the maximum torque value Tmax and the optimum current phase β for realizing the torque value when the magnetic flux shift amount θ (deg) is appropriately changed. It is.

Here, the amount of magnetic flux shift indicates the amount of movement of magnetic flux that changes depending on the magnet arrangement. The maximum torque value indicates the maximum value of the combination of the framing torque and the reluctance torque. The current phase indicates the timing at which the stator coil is energized. Note that a torque difference is generated at this timing.

According to this graph, the magnetic flux shift amount θ (de
It can be seen that the maximum torque value Tmax increases as g) approaches 45 ° in electrical angle (22.5 ° in mechanical angle).

Next, regarding the peak value of the magnet magnetic flux distribution,
References (Design of ferrite magnet rotating machine (Mitsuyoshi Okawa, T
DK)) will be described.

First, the permeance coefficient P determines the operating point of the magnet and is expressed by the following equation (6).

[0078]

(Equation 6)

Here, Lm: magnet thickness Ag: air gap sectional area kf: magnetomotive force loss coefficient Lg: air gap length Am: magnet sectional area kr: leakage coefficient

In the above equation (6), basic motor parameters (air gap length Lg, air gap sectional area A
g, the magnetomotive force loss coefficient kf, and the leakage coefficient kr) are the same, the permeance coefficient P is proportional to the magnet thickness Lm and inversely proportional to the magnet cross-sectional area Am. The larger the permeance coefficient P is, the higher the magnet operating point becomes, and the higher the magnetic flux density of the magnet used can be obtained.

Therefore, as a desirable form, by setting the circumferential length of the first permanent magnet 3 to be arranged short, the magnet thickness can be increased if the magnet volume is the same.
The permeance coefficient P can be further increased.

As described above, the slits 1a
On the basis of the q-axis, which is a line connecting the center between 1a and the center of the rotor 1, the first permanent magnet 3
By arranging the reluctance torque Tr and the framing torque Tm at a peak position near 5 ° and near the outer peripheral surface, deviation of the peak position between the reluctance torque Tr and the framing torque Tm can be eliminated, and high torque and high efficiency can be realized in an optimal current phase. Moreover, since the permeance coefficient P can be increased, the magnet capability can be effectively used, and a higher torque can be realized.

As described above, by arranging the first permanent magnet 3 so as to face the stator 6 on the outer peripheral surface, the magnet flux is concentrated on a desired region, thereby reducing the framing torque and the reluctance torque. It is possible to make the peaks substantially coincide with each other, and it is possible to achieve high torque and high efficiency such as reduction of the equivalent air gap and reduction of leakage magnetic flux.

The surface arrangement of the first permanent magnet 3 and the method of holding the magnet will be described in detail with reference to FIGS.

For example, as shown in FIG. 4, when the first permanent magnet 83 is arranged so that its surface faces the stator winding 7 wound around the teeth 8 of the stator 6, it is shown in FIG. As with the DC brushless motor, the notch 81
The center of the first permanent magnet 83 has an electrical angle of 45 ° (mechanical angle 2) based on a line connecting the center of the rotor 81 and the center of the rotor 81.
A method is conceivable in which the first permanent magnet 83 is arranged so as to be exposed to the outer peripheral surface at about 2.5 °) and both ends 83a and 83b of the first permanent magnet 83 are formed in a wedge shape.

In this case, the notch 81b of the rotor 81 corresponding to the first permanent magnet 83 also has a wedge-shaped shape opposite to the wedge-shaped shape of both ends 83a and 83b of the first permanent magnet 83. In addition, the first permanent magnet 83 can be inserted along the rotation axis from the upper surface of the rotor 81, and the scattering of the first permanent magnet 83 when the rotor 81 rotates can be prevented.

As shown in FIG. 5, both ends 93a and 93b of the first permanent magnet 93 may be desirably stepped. Notch 91b of rotor 91 corresponding to this
Has a stepped shape corresponding to both ends 93a and 93b of the first permanent magnet 93, and enables the first permanent magnet 93 to be inserted along the central axis from the upper surface of the rotor 91, This makes it possible to prevent the first permanent magnet 93 from scattering when the rotor 91 rotates.

Further, as shown in FIG. 6, both end portions 103a and 103b of the first permanent magnet 103 are desirably straight, but a non-magnetic material 109 is provided on the upper portion of the first permanent magnet 103. The first permanent magnet 103 can be inserted along the central axis from the upper surface of the rotor 101 by press-fitting into the cutout portion 101b on the outer peripheral surface of the rotor 101, and the first permanent magnet 103 is rotated when the rotor 101 rotates. The scattering of the permanent magnet 103 can be prevented.

In the present embodiment, a DC brushless motor in a state where nothing but air is inserted into the slit 1a formed in the rotor 1 has been described. An example in which a permanent magnet is inserted will be described.

[Embodiment 2] DC according to the present embodiment
As shown in FIG. 7, the brushless motor has a configuration in which the second permanent magnet 2 is inserted into the slit 1a of the rotor 1 in the DC brushless motor shown in FIG. 1 described in the first embodiment. .

The second permanent magnets 2 are arranged in the same manner as the first permanent magnets 3, and are magnetized in the same polarity as the first permanent magnets 3.

In the DC brushless motor having the above structure, since the second permanent magnet 2 is disposed inside the rotor 1, the equivalent magnet surface area is increased, and the framing torque Tm can be increased. Similarly, as shown in the section of the prior art, the rotor 1 is formed in a substantially arc-shaped cross section that is convex toward the center side of the rotor 1 and both end portions extend to positions near the outer peripheral surface of the rotor 1 (1). Since the difference (Ld-Lq) in the inductance of the expression (2) becomes large, the reluctance torque Tr can be increased.

Therefore, in the DC brushless motor having the above-described structure, the total torque is improved as compared with the DC brushless motor of the first embodiment because the second permanent magnet 2 is disposed in the rotor 1. The motor is suitable not only for high rotation but also for low rotation.

In the first and second embodiments, the shape of the slit 1a, which is the gap of the rotor 1, is substantially arc-shaped in cross section in which the center is convex toward the rotation shaft 4 side. The shape of the permanent magnet 2 is also matched to the shape of the slit 1a. However, the present invention is not limited to this, and slits of other shapes and second permanent magnets may be used. Examples of such other shapes will be described below. Here, for convenience, D shown in FIG.
Only members different in configuration from the C brushless motor will be described, and the same members will be denoted by the same reference numerals and description thereof will be omitted.

[Embodiment 3] DC according to the present embodiment
The brushless motor includes a rotor 21 instead of the rotor 1 shown in FIG. 1 as shown in FIG. 8, for example.

The rotor 21 has the same shape as the rotor 1 shown in FIG. 1, except that the shape of the vicinity of the center of the slit 21a of the rotor 21 is substantially rectangular in cross section.
The portion of the rotor 1a near the outer peripheral surface is bent at a predetermined distance from the center. In accordance with this, the shape of the second permanent magnet 22 inserted into the slit 21a is also substantially rectangular. The slit 21a
Although the magnets are not inserted into the bent portions on both end sides, they may be inserted.

The second permanent magnet 22 described above is
Similarly to the above, four permanent magnets are arranged, and the polarity of each permanent magnet is magnetized as shown in FIG.

According to the DC brushless motor having the above configuration, since the second permanent magnet 22 has a substantially rectangular cross section, the second permanent magnet 22 has a rectangular parallelepiped shape. The manufacturing of the permanent magnet 22 is easy,
The manufacturing and processing of the C brushless motor is easy, and mass productivity can be improved.

[Embodiment 4] DC according to the present embodiment
The brushless motor includes a rotor 31 instead of the rotor 1 shown in FIG. 1, for example, as shown in FIG.

The rotor 31 differs from the rotor 1 shown in FIG. 1 in the shape of the slit 31a and the second permanent magnet 32. The shape of the slit 31a is bent into two around the d-axis so that the central portion becomes convex toward the rotation shaft 4, and each region has a substantially rectangular cross section. Each of the two areas of the slit 31a has a slit 3
A rectangular parallelepiped second permanent magnet 32 conforming to the shape of 1a is fitted therein. In this case, eight second permanent magnets 32 are arranged in the rotor 31, and the polarity of each second permanent magnet 32 is magnetized as shown in FIG. The pairs are arranged such that the polarities are inverted.

According to the DC brushless motor having the above structure, the shape of the second permanent magnet 32 fitted into the rotor 31 is a rectangular parallelepiped, so that it is easy to manufacture and process, and is excellent in mass productivity.
Further, the fleming torque increases due to the increase in the equivalent magnet surface area as the reluctance torque increases.

[Embodiment 5] DC according to the present embodiment
For example, as shown in FIG.
A rotor 41 is provided in place of the rotor 1 shown in FIG.

The rotor 41 is, as shown in FIG.
Three slits 41a are formed for each pole. Similar to the slit 1a shown in FIG. 1, the shape of the slit 41a is a substantially arc-shaped cross section in which the central portion is convex toward the rotation shaft 4 side.

Then, the end 41a 'of each slit 41a
Are formed close to the surface of the rotor 41.

A second permanent magnet 42 conforming to the shape of each slit 41a is fitted in each slit 41a.

According to the DC brushless motor configured as described above, since the second permanent magnet 42 is increased in one pole, the equivalent magnet surface area is increased, and the framing torque can be increased. Further, since the slit 41a is also increased in one pole, the reluctance torque is also increased.

As a result, the total torque of the DC brushless motor having the above configuration is improved as compared with the DC brushless motor shown in FIG. Therefore, FIG.
According to the DC brushless motor described in (1), high torque can be realized.

The number of the slits 41a in one pole of the rotor 41 is not limited to three, but may be more than three. In this case, the framing torque can be further improved.

[Embodiment 6] DC according to the present embodiment
As shown in FIG. 11, the brushless motor has a rotor 51 in which three slits 51a each having the same shape as the slit 41a shown in FIG. 10 are arranged at each pole. The configuration is such that the second permanent magnet 52 is fitted only into the slit 51a closest to the rotation shaft 4 among the slits 51a.

According to the DC brushless motor having the above-described configuration, since each pole of the rotor 51 is provided with a plurality of slits 51a, the reluctance torque can be increased.

Incidentally, since the second permanent magnet 52 is fitted in only one of the three slits 51a of each pole, the framing torque is reduced as compared with the DC brushless motor shown in FIG. I have. However, by compensating for the reduction in the Fleming torque with the increase in the reluctance torque, it is possible to substantially increase the total torque.

Furthermore, as compared with the DC brushless motor shown in FIG. 10, the induced voltage by the second permanent magnet 52 can be reduced by the amount of the magnet which is smaller. This allows
High-speed rotation of the DC brushless motor can be easily performed, and the volume of the second permanent magnet 52 can be reduced, so that the cost can be reduced.

Accordingly, the DC brushless motor shown in FIG. 11 is a motor suitable for high-speed rotation.

If the first permanent magnet 52 is inserted into two of the three slits 51a, the framing torque can be improved, and as a result, the total torque can be further improved. By forming a plurality of slits 51a at one pole of the rotor 51, the degree of freedom in designing the DC brushless motor is increased, and the DC brushless motor can be easily designed with specifications desired by the user.

[Embodiment 7] DC according to the present embodiment
For example, as shown in FIG.
Is provided with a rotor 61 having substantially the same configuration as the rotor 1 shown in FIG.

In the rotor 61, the rotor 1 shown in FIG.
61a having substantially the same shape as the slit 1a in FIG.
Are formed. A second permanent magnet 62 is fitted into the slit 61a in a half area around the d-axis. The first permanent magnet 3 is arranged at a predetermined position on the surface of the rotor 61, similarly to the rotor 1 shown in FIG.

The second permanent magnet 62 is fitted in the area of the slit 61a on the side close to the first permanent magnet 3, and is magnetized as shown in FIG.
The pairs are arranged such that the polarities are inverted.

According to the DC brushless motor having the above configuration, the surface area of the second permanent magnet 62 is smaller than that of the DC brushless motor shown in FIG. 1, so that the framing torque is reduced. , Rotation at high speed is possible, and cost reduction can be realized by reducing the magnet volume.

[Eighth Embodiment] A DC according to this embodiment
For example, as shown in FIG.
A rotor 71 having substantially the same configuration as the rotor 41 shown in FIG.

In the rotor 71, as in the first embodiment, the first permanent magnets 3 are disposed at predetermined positions on the surface, but the second permanent magnets are fitted in the respective slits 71a. There is no configuration.

Accordingly, in the DC brushless motor having the above structure, although the framing torque is reduced, the induced voltage by the magnet is small, high-speed rotation is possible, and the concentration of the magnetic flux on the desired portion is increased, so that the magnetic flux can be effectively used. In addition, the cost can be reduced by reducing the magnet volume.

In the above-described first to eighth embodiments, the example in which the present invention is applied to a DC brushless motor has been described. However, the present invention can be applied to an AC brushless motor.

[0123]

The brushless motor according to the first aspect of the present invention
As described above, the rotor and the stator, which is disposed close to the outer peripheral surface of the rotor and has a stator in which a winding is wound around a stator core for supplying a driving force to the rotor, The rotor has a first axis that is a straight line connecting the rotation axis of the rotor and the outer peripheral surface, and a second axis that is a line that passes through the rotation axis and is electrically orthogonal to the first axis. The reluctance of the rotor in the first region through which the first axis passes and the second region through which the second axis passes
The magnetic resistance is different from that of the region, and a permanent magnet center is disposed near the outer peripheral surface of the rotor on the acute angle side surrounded by the first axis and the second axis.

Therefore, the difference between the peak of the fleming torque and the peak of the reluctance torque can be reduced, and as a result, the overall torque of the motor can be improved.

According to the brushless motor of the second aspect of the present invention, as described above, in addition to the configuration of the first aspect, the rotor has a structure in which the rotation axis is parallel to the rotation axis of the rotor and near the center. A plurality of voids having a shape substantially convex toward the periphery and having both ends extending to near the surface of the rotor are formed around the rotation axis, and the voids are not included in the first region, And the second
The configuration is included in the area.

Therefore, in addition to the effect of the first aspect, the magnetic permeability of the air gap may be considered to be the same as that of air. As a result, the magnetic resistance of the second axis passing through the air gap is reduced. It is larger than the magnetic resistance of the first axis that does not pass through. Thus, a difference in magnetic resistance can be easily generated only by providing a gap inside the rotor.

In addition, since the center of the gap is convex toward the rotation axis of the rotor, and both ends of the gap extend to near the surface of the rotor, the inductance of the first shaft and the second axis are reduced. Since the difference from the inductance of the shaft can be further increased, there is an effect that the reluctance torque can be increased.

A brushless motor according to a third aspect of the present invention has a configuration in which a permanent magnet is fitted into a gap as described above, in addition to the configuration of the second aspect.

Therefore, in addition to the effect of the configuration of the second aspect, the permanent magnet is fitted in the gap, so that the permanent magnet is disposed inside the rotor. As a result, the equivalent magnet surface area of the rotor is increased, and the framing torque can be increased. As a result, the effect of increasing the total torque can be achieved.

According to the brushless motor of the fourth aspect of the present invention, as described above, in addition to the configuration of any one of the first to third aspects, the permanent magnet near the outer peripheral surface of the rotor has a fixed surface of the stator. This is a configuration that is arranged so as to face the side surface of the winding wound around the core.

Therefore, in addition to the effect of any one of the first to third aspects, the permanent magnet is arranged so that the surface thereof faces the stator, thereby reducing the magnetic flux of the magnet.
By concentrating on a desired region, it becomes possible to make the peaks of the fleming torque and the reluctance torque substantially coincide with each other. Therefore, since the equivalent air gap can be reduced and the leakage flux can be reduced, it is possible to provide a brushless motor having high torque and high efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a DC brushless motor of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a q-axis and a d-axis of the DC brushless motor shown in FIG.

FIG. 3 is a graph showing a relationship between a magnetic flux shift and a torque ratio in the DC brushless motor shown in FIG.

FIG. 4 is an explanatory diagram showing an example of a relationship between a first permanent magnet and a rotor in the DC brushless motor of the present invention.

FIG. 5 is an explanatory diagram showing another example of the relationship between the first permanent magnet and the rotor in the DC brushless motor of the present invention.

FIG. 6 is an explanatory diagram showing still another example of the relationship between the first permanent magnet and the rotor in the DC brushless motor of the present invention.

FIG. 7 is a schematic configuration diagram showing another example of the DC brushless motor of the present invention.

FIG. 8 is a schematic configuration diagram showing still another example of the DC brushless motor of the present invention.

FIG. 9 is a schematic configuration diagram showing still another example of the DC brushless motor of the present invention.

FIG. 10 is a schematic configuration diagram showing still another example of the DC brushless motor of the present invention.

FIG. 11 is a schematic configuration diagram showing still another example of the DC brushless motor of the present invention.

FIG. 12 is a schematic configuration diagram showing still another example of the DC brushless motor of the present invention.

FIG. 13 is a schematic configuration diagram showing still another example of the DC brushless motor of the present invention.

FIG. 14 is a schematic configuration diagram of a conventional brushless motor.

FIG. 15 is a schematic configuration diagram of a conventional brushless motor.

FIG. 16 is a graph showing a relationship among a fleming torque, a reluctance torque, and a total torque in the brushless motor shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 1a Slit (gap part) 1b Notch part 2 2nd permanent magnet 3 First permanent magnet 4 Rotation axis 5 Straight line (1st axis) 6 Stator 7 Stator winding (winding) 8 Teeth (stator) Iron core) 9 straight line (second axis) 21 rotor 21a slit (gap) 22 second permanent magnet 31 rotor 31a slit (gap) 32 second permanent magnet 41 rotor 41a slit (gap) 42 first Second permanent magnet 51 Rotor 51a Slit (gap) 52 Second permanent magnet 61 Rotor 61a Slit (gap) 62 Second permanent magnet 71 Rotor 71a Slit (gap) 81 Rotor 81b Notch 83 first permanent magnet 91 rotor 91b notch 93 first permanent magnet 101 rotor 101b notch 103 first permanent magnet

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H002 AA09 AB07 AD04 AE08 5H619 AA01 BB01 BB06 BB13 BB15 BB24 PP02 PP06 PP08 5H622 AA03 CA02 CA05 CA10 CB04 CB05 PP03 PP10 PP11 QB02 QB05

Claims (4)

[Claims] 1. A rotor, comprising: a rotor disposed in close proximity to an outer peripheral surface of the rotor and having a winding wound around a stator core for supplying a driving force to the rotor; The rotor has a first axis that is a straight line connecting the rotation axis of the rotor and the outer peripheral surface, and a second axis that is a line that passes through the rotation axis and is electrically orthogonal to the first axis. The rotor is formed so that the magnetic resistance of the first region through which the first axis passes is different from the magnetic resistance of the second region through which the second shaft passes, and is surrounded by the first shaft and the second shaft. A brushless motor, wherein a permanent magnet center is disposed near the outer peripheral surface of the rotor on the acute angle side. 2. The rotor according to claim 1, wherein the rotor is parallel to the rotation axis of the rotor, the central portion is substantially convex toward the rotation axis, and both ends extend to near the surface of the rotor. 2. The brushless motor according to claim 1, wherein a plurality of voids having a shape are formed around the rotation axis, and the voids are not included in the first region and are included in a second region. 3. 3. The brushless motor according to claim 2, wherein a permanent magnet separate from a permanent magnet disposed near an outer peripheral surface of the rotor is fitted into the gap. 4. A permanent magnet in the vicinity of an outer peripheral surface of the rotor is arranged so that a surface thereof faces a side surface of a winding wound around a stator core of the stator.
4. The brushless motor according to any one of claims 1 to 3.