JP2009254143A - Rotor and embedded magnet motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent local demagnetization of permanent magnets at portions near air gaps. <P>SOLUTION: A rotor 20, which has a roughly cylindrical shape with a center axis roughly parallel to a rotating shaft 12 and faces a stator 14 via air gaps, includes a rotor core 22 formed roughly in a cylindrical shape and a plurality of magnet pole portions embedded in the rotor core 22 in such a manner to be formed along the circumferential direction around the rotating shaft 12. The magnet pole portions have the permanent magnets 30, which are formed roughly like a plate, which are embedded in each magnet embedding recessed portion 24 formed in the rotor core 22 in such a way as to have proximity portions 32 near the air gaps and a distant portion 34 more apart from the air gaps than the proximity portions 32, and which show anisotropy that the axes A of easy magnetization are inclined to the thickness direction from the proximity portions 32 toward the distant portion 34. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotor in which a permanent magnet is embedded in a rotor core and an embedded magnet type motor.

  An embedded magnet type motor can use reluctance torque due to its (reverse) saliency, and can realize a relatively high torque. Moreover, the operating range can be expanded to a higher speed by performing the flux-weakening control.

  On the other hand, in an embedded magnet type motor, which is a kind of brushless motor, it is difficult to accurately grasp the position of the rotor and flow current in a transient or abnormal state. Under such a state, the permanent magnet embedded in the rotor has a portion that is likely to be demagnetized locally due to the embedded portion.

  As a countermeasure against such demagnetization, a configuration in which the magnet thickness and the coercive force of the permanent magnet material are determined in accordance with a place where local demagnetization is likely to occur. However, in this case, the quality is excessive with respect to the demagnetization except in the portion where the demagnetization is easy. In addition, in order to increase the coercive force of the permanent magnet material, for example, a special element is added, for example. However, in this case, the residual magnetic flux density of the permanent magnet is lowered. That is, although a rare element is added to increase the coercive force, the residual magnetic flux density is lowered and the magnetic energy product is also reduced.

  For this reason, it is preferable to take a local demagnetization countermeasure for the permanent magnet. Usually, in the case of an inner rotor type embedded magnet type motor, a portion of the permanent magnet close to the air gap, that is, a circumferential end portion of the permanent magnet is easily demagnetized.

  As a measure against local demagnetization, as disclosed in Patent Document 1, a technique is provided in which a gap is provided at a circumferential end of a permanent magnet so that when a demagnetizing field is generated, the magnetic flux due to the demagnetizing field easily passes through the gap. is there.

  Further, as disclosed in Patent Document 2, there is a technique that uses a magnetic material having a high coercive force at the end of a permanent magnet.

JP 2000-50543 A JP-A-10-271722

  However, in the technique disclosed in Patent Document 1, it is necessary to increase the gap in order to increase the effect of preventing demagnetization. However, when the gap is increased, the amount of permanent magnets is decreased. For this reason, there is a circumstance that it is desired to make the gap as small as possible.

  Moreover, in the technique disclosed in Patent Document 2, it is necessary to separately combine a permanent magnet with the demagnetization countermeasure portion.

  Therefore, an object of the present invention is to prevent local demagnetization of a permanent magnet at a portion close to an air gap.

  In order to solve the above-described problem, the rotor according to the first aspect includes a rotor (20, 620) facing the stator (14) through a substantially cylindrical air gap having a central axis substantially parallel to the rotation shaft (12). The rotor core (22, 622) formed in a substantially cylindrical shape, and a plurality of magnetic pole portions embedded in the rotor core in a form along the circumferential direction around the rotation axis, the magnetic pole portion Is formed in a substantially plate shape, near the end of the magnetic pole, close to the air gap (32, 132, 432, 632) and closer to the magnetic pole center than the close part, and from the air gap It is embedded in a magnet embedded recess (24, 124, 624) formed in the rotor core in a form having a distant portion (34), and an easy magnetization axis (A) is provided from the distant portion toward the close portion. Thickness And it has a permanent magnet (30,130,430,630) which exhibits anisotropy inclined to.

  A 2nd aspect is a rotor which concerns on a 1st aspect, Comprising: The said permanent magnet (30,130,430,630) is a rare earth sintered magnet.

  A 3rd aspect is a rotor which concerns on a 1st or 2nd aspect, Comprising: The said permanent magnet (30,130,430,630) is a Nd-Fe-B type magnet.

  A fourth aspect is the rotor according to any one of the first to third aspects, wherein the permanent magnet (130) has a surface substantially perpendicular to the rotation axis substantially the same in a direction along the rotation axis. It is formed into a shape, and is formed by applying an orientation magnetic field in a direction (P2) substantially orthogonal to the rotation axis while compressing in the direction (P1) of the rotation axis.

  A fifth aspect is the rotor according to any one of the first to fourth aspects, wherein the permanent magnet has anisotropy in which an easy axis of magnetization is radially oriented.

  The permanent magnets (30, 130, 430, 630) have anisotropy in which the easy magnetization axis (A) is radially oriented.

  A sixth aspect is the rotor according to any one of the first to fifth aspects, wherein the permanent magnet (30, 130, 430, 630) is the proximity portion (32, 132, 432, 632). Have anisotropy oriented so that the easy axis (A) of the magnet tilts toward the far portion (34) toward the stator.

  A seventh aspect is the rotor according to any one of the first to sixth aspects, wherein the adjacent portions (32, 132, 632) are arranged in an orientation direction of the easy axis (A) in the adjacent portions. It has a substantially parallel slope (33a, 133a).

  An eighth aspect is the rotor according to any one of the first to seventh aspects, wherein the permanent magnets (30, 130, 630) are formed in a substantially trapezoidal shape on a surface substantially orthogonal to the rotation axis. It is what.

  A ninth aspect is the rotor according to the seventh or eighth aspect, wherein the proximity portion (132) is in contact with the slope (133a) of the proximity portion and the main surface of the permanent magnet (130). It has an acute angle relaxation surface (133b) that intersects at a substantially right angle or a substantially obtuse angle.

  A tenth aspect is the rotor according to the ninth aspect, wherein the magnet-embedded recess (124) is capable of abutting on an intersection of the acute angle relaxation surface of the adjacent portion and the main surface of the permanent magnet. A protrusion (124a) is formed.

  The eleventh aspect is the rotor according to the ninth or tenth aspect, wherein the length dimension (L3) of the inclined surface of the adjacent portion between both main surfaces of the permanent magnet is the thickness of the permanent magnet. It is the dimension (L4) or more.

  A twelfth aspect is a rotor according to any one of the first to eleventh aspects, wherein both main surfaces of the permanent magnets (30, 130, 430, 630) are formed on the magnet-embedded recesses (24, 124, 624) is substantially in contact with the inner surface.

  A thirteenth aspect is the rotor according to any one of the first to twelfth aspects, wherein the anti-air gap facing surface of the permanent magnets (30, 130, 630) is larger than the air gap facing surface. It is.

  A fourteenth aspect is a rotor according to any one of the first to thirteenth aspects, wherein the rotor core has a gap (28, 228, 228B, 328) adjacent to the adjacent portion. .

  A fifteenth aspect is the rotor according to the fourteenth aspect, wherein the gap (28, 228, 228B, 328) includes an edge of the adjacent portion and the rotor core, and the width of the magnet-embedded recess. It is formed in a shape that is opposed to each other through a gap (L1) having a dimension (L2) or more.

  A sixteenth aspect is a rotor according to the fourteenth or fifteenth aspect, wherein a pair of the gap portions (228) are formed adjacent to both magnetic pole ends of the magnetic pole portion, and the rotation axis is used as a reference. The spread angle (θ2) of the core portion provided between the pair of gap portions with respect to the rotation axis is smaller than the spread angle (θ1) of the magnetic pole portion.

  A seventeenth aspect is the rotor according to any one of the fourteenth to sixteenth aspects, wherein the gap (328) is formed in a shape in which the gap width decreases toward the air gap side. It is.

  An embedded magnet type motor according to an eighteenth aspect is opposed to the rotor (20, 620) according to any one of the first to seventeenth aspects via the substantially cylindrical air gap. A coil (17).

  According to the rotor according to the first aspect, the permanent magnet exhibits anisotropy in which the easy magnetization axis is inclined with respect to the thickness direction from the remote portion toward the close portion. It is possible to increase the substantial thickness of the permanent magnet at a portion that is easy to do, that is, a portion near the air gap, and it is possible to prevent local demagnetization of the permanent magnet at a portion near the air gap.

  According to the second aspect, since the permanent magnet is a rare earth sintered magnet, the magnetic energy product can be increased.

  According to the 3rd aspect, since the said permanent magnet is a Nd-Fe-B type magnet, especially a magnetic energy product can be enlarged.

  According to the fourth aspect, the permanent magnet has a shape in which a surface substantially orthogonal to the rotation axis has substantially the same shape in the direction along the rotation axis, and the rotation axis is compressed in the direction of the rotation axis. Since the magnetic field is formed by applying an orientation magnetic field in a direction substantially perpendicular to the magnetic field, the density can be increased, and the strength and magnetic characteristics such as magnetic flux density can be improved.

  According to the fifth aspect, it is possible to easily manufacture a permanent magnet having anisotropy in which the easy magnetization axis is radially oriented.

  According to the sixth aspect, the permanent magnet has anisotropy oriented so that the easy magnetization axis in the proximity portion is inclined toward the distant portion toward the stator side, so that the magnetic flux It can be concentrated at the center and high torque can be realized.

  In the seventh aspect, it is possible to prevent a magnetic short-circuit at an unnecessary portion by making it difficult to present a magnetic pole on the surface of the adjacent portion.

  According to the 8th aspect, since the surface of an adjacent part inclines, it is hard to exhibit a magnetic pole and can prevent the magnetic short circuit in an unnecessary part.

  According to the 9th aspect, an acute angle can be relieved in a proximity part, a permanent magnet can be manufactured easily, and a chip can be prevented.

  According to the tenth aspect, the magnet-embedded recess is formed with a protrusion capable of contacting the intersection of the acute angle relaxation surface of the adjacent portion and the main surface of the permanent magnet. Thus, the movement of the permanent magnet can be suppressed.

  According to the eleventh aspect, since the length dimension of the slope of the adjacent portion between the main surfaces of the permanent magnet is equal to or greater than the thickness dimension of the permanent magnet, it is possible to effectively prevent demagnetization. it can.

  According to the twelfth aspect, the magnetic resistance can be reduced between the permanent magnet and the rotor core.

  According to the thirteenth aspect, since the anti-air gap facing surface of the permanent magnet is larger than the air gap facing surface, the magnetic path passing through the rotor core between the permanent magnets can be shortened.

  Further, according to the fourteenth aspect, since the rotor core has a gap portion adjacent to the adjacent portion, when a demagnetizing field is generated, the magnetic flux due to the demagnetizing field easily passes through the gap portion. Magnetic prevention can be achieved.

  According to the fifteenth aspect, the edge portion of the proximity portion and the rotor core are opposed to each other through a gap that is equal to or larger than the width dimension of the magnet-embedded recess, and therefore, between the edge portion of the proximity portion and the rotor core. The magnetic resistance can be increased as much as possible.

  According to the sixteenth aspect, the spread angle of the core portion provided between the pair of gaps with respect to the rotation axis is smaller than the spread angle of the magnetic pole portion with respect to the rotation axis. Magnetic flux can be collected by the magnetic pole center.

  According to the seventeenth aspect, since the gap is formed in a shape in which the gap width becomes smaller toward the air gap side, the demagnetizing field can be released at the portion where the gap width is reduced.

  According to the eighteenth aspect, it is possible to obtain an embedded magnet type motor that is intended to prevent local demagnetization of the permanent magnet at a portion close to the air gap.

  Hereinafter, the rotor and the embedded magnet type motor according to the embodiment will be described. FIG. 1 is a cross-sectional view showing an embedded magnet type motor 10 according to the embodiment, FIG. 2 is a cross-sectional view showing a rotor 20, and FIG. 3 is a partially enlarged view showing the vicinity of the end of the permanent magnet 30 in FIG. It is. 1 to 3 show a cross section perpendicular to the rotating shaft 12. 1 to 3 and the following drawings, a shaft connected to the rotor 20 and transmitting a rotational force to the outside is not shown.

  The embedded magnet type motor 10 includes a rotor 20 and a stator 14. The rotor 20 is formed in a substantially cylindrical appearance, and a shaft (not shown) is connected and fixed along the central axis. The central axis of the rotor 20 becomes the rotating shaft 12 of the motor 10. The stator 14 includes a yoke portion 15 and a plurality of (here, six) teeth portions 16. The yoke portion 15 is formed in a substantially cylindrical shape having an inner peripheral diameter larger than the outer peripheral diameter of the rotor 20. The plurality of teeth portions 16 are distributed at substantially equal intervals along the circumferential direction of the yoke portion 15 (hereinafter referred to as the circumferential direction refers to the circumferential direction of a circle centered on the rotation shaft 12). Projected in a manner. Each tooth portion 16 extends from the inner peripheral portion of the yoke portion 15 along the radial direction of a circle centering on the rotation shaft 12 to the rotation shaft 12 side, and faces the rotor 20 via a gap. Each tooth portion 16 is magnetically coupled via a yoke portion 15 on the outer peripheral side. A coil 17 is wound around each of the teeth portions 16 as an armature winding (only one is shown in FIG. 1), and the coil 17 is opposed to the rotor 20 via an outer peripheral gap. ing. Three-phase alternating current for generating a rotating magnetic field for rotating the rotor 20 is passed through the coil 17. The winding method of the coil 17 is not particularly limited, and may be a concentrated winding form with respect to the plurality of tooth portions 16 or a distributed winding form.

  The rotor 20 and the stator 14 are used as a rotating electric machine by being incorporated in a casing or the like (not shown) in a mode of facing through a substantially cylindrical air gap having a central axis substantially parallel to the rotating shaft 12.

  The rotor 20 will be described in more detail.

  The rotor 20 includes a rotor core 22 and a plurality (four in this case) of permanent magnets 30.

  The rotor core 22 is formed in a substantially cylindrical shape from a magnetic material, and a shaft insertion hole 23 for fixing a shaft (not shown) is formed along the central axis (rotating shaft 12). The rotor core 22 is formed with a plurality (four in this case) of magnet-embedded recesses 24 along the circumferential direction around the rotary shaft 12. The magnet-embedded recess 24 is formed in a substantially rectangular parallelepiped space that is flat in a direction substantially orthogonal to the radial direction of the circle centered on the rotating shaft 12. The magnet embedding concave portion 24 may be a penetrating hole shape or a bottomed concave shape as long as the permanent magnet 30 can be embedded therein. Moreover, the space | gap part 28 extended toward the outer peripheral side along the said radial direction from the said circumferential direction both ends among the magnet embedding recessed parts 24 is formed. The gap 28 is formed at a position adjacent to a proximity portion 32 (described later) of the permanent magnet 30. When a demagnetizing field is generated, the magnetic flux generated by the demagnetizing field has a role of avoiding the permanent magnet 30 and easily passing through the gap portion 28, and this gap portion 28 also prevents demagnetization. A more preferable shape of the gap 28 will be described later in relation to the permanent magnet 30.

  Each of the plurality of permanent magnets 30 is disposed in an embedded manner in each of the magnet embedding recesses 24. Here, each permanent magnet constitutes a magnetic pole part, whereby a plurality of magnetic pole parts are embedded in the rotor core 22 along the circumferential direction around the rotating shaft 12. The permanent magnet 30 is formed in a substantially plate shape (here, a substantially rectangular plate shape having a substantially uniform thickness) having two main surfaces, and a circle centered on the rotary shaft 12 is formed in the magnet-embedded recess 24. It arrange | positions with the attitude | position extended in the direction substantially orthogonal to radial direction. Here, the outward surface of the permanent magnet 130 is a magnetic pole surface (also referred to as an air gap facing surface) that presents a magnetic pole with respect to the rotor core 22, and the inward surface is the opposite anti-magnetic surface (an anti air gap facing surface). ). Further, if the permanent magnet 30 is regarded as a portion that exhibits a magnetic pole with respect to the stator 14, both circumferential ends of the permanent magnet 30 are magnetic pole ends, and a substantially central portion in the circumferential direction is a magnetic pole center.

  In the posture of the permanent magnet 30 as described above, both end portions in the circumferential direction of the permanent magnet 30 are close to the end portions of the magnetic poles, and are close to the air gap 32. The far portion 34 is closer to the magnetic pole center than the close portion 32 and far from the air gap. However, the magnetic pole may be constituted by a combination of a plurality of permanent magnets, and in this case, the distant portion 34 may not be located in the circumferential central portion of the magnetic pole. That is, the proximity portion 32 close to the air gap and the far portion 34 far from the air gap are portions that are relatively grasped based on the positional relationship between the permanent magnet and the air gap. However, when one magnetic pole is formed by a combination of a plurality of permanent magnets, if it is grasped as one magnet group, the proximity portion coincides with the magnetic pole end.

  Further, the thickness dimension of the permanent magnet 30 and the dimension of the magnet-embedded recess 24 in the thickness direction of the permanent magnet 30 are formed substantially the same, and both main surfaces of the permanent magnet 30 are substantially the inner surface of the magnet-embedded recess 24. Is in contact with Here, when both main surfaces of the permanent magnet 30 are substantially in contact with the inner surface of the magnet embedding recess 24, there is a minute gap that is necessary when the permanent magnet 30 is inserted into the magnet embedding recess 24. The case where it arises between the permanent magnet 30 and the magnet embedding recessed part 24 is also included. By doing so, the magnetic resistance can be reduced between the permanent magnet 30 and the rotor core 22.

  Further, the permanent magnet 30 exhibits anisotropy in which the easy axis (see arrow A) is inclined with respect to the thickness direction from the remote portion 34 toward the close portion 32.

  Here, the permanent magnet 30 exhibits anisotropy that is oriented so that the easy axis of magnetization in the proximity portion 32 is inclined toward the far portion 34 toward the stator 14 side (here, the outer peripheral side). Further, the far portion 34 in the central portion in the circumferential direction of the permanent magnet 30 is a magnetic pole center and has anisotropy oriented substantially parallel to the thickness direction. As a result, when viewed from the permanent magnet 30 as a whole, the magnetic flux is concentrated on the magnetic pole center, which is the distant portion 34, on the stator 14 side. Thereby, high torque can be realized as the motor 10 characteristic.

  Further, here, the inclination angle of the easy magnetization axis with respect to the thickness direction of the permanent magnet 30 is gradually increased from the far portion 34 toward the close portion 32, and the permanent magnet 30 has a different orientation in which the easy magnetization axis is radially oriented. It exhibits directionality. Specifically, the permanent magnet 30 is centered on a point B on the stator 14 side (here, the air gap side) with respect to the permanent magnet 30 (the center of radial orientation is also indicated by a point B in each of the following drawings). Radial orientation as shown in FIG. More specifically, the permanent magnet 30 is radially oriented so that the permanent magnet 30 has a center on the air gap side from the permanent magnet 30 on a line connecting the rotating shaft 12 and the magnetic pole center (here, the central portion in the circumferential direction) of the permanent magnet 30. Anisotropy. Since the radially oriented permanent magnet 30 can be formed with a magnetic field orientation that can be easily realized at the time of molding, there is an advantage that it can be easily manufactured.

  From the viewpoint of easy manufacture, the center when the permanent magnet 30 is radially oriented may be on the side opposite to the air gap (here, the inner peripheral side) with respect to the permanent magnet 30.

  Further, the proximity portion 32 of the permanent magnet 30 has a slope 33 a that is substantially parallel to the orientation direction of the easy axis of magnetization in the proximity portion 32. Here, since the easy axis of magnetization in the proximity portion 32 is inclined toward the far portion 34 toward the air gap side, the inclined surface 33a is located toward the far portion 34 side, that is, the permanent magnet 30 toward the air gap side. Is inclined substantially toward the center in the circumferential direction. Here, on the extension of the inclined surface 33a, there is the center of the easy-magnetization axis in the radial orientation. When viewed as a whole of the permanent magnet 30, the surface substantially orthogonal to the rotating shaft 12 has a substantially trapezoidal shape (here, a substantially isosceles trapezoidal shape) having a long side on the outer peripheral side and a short side on the inner peripheral side. . As a result, the end face of the proximity portion 32 does not exhibit a magnetic pole, or even if a magnetic pole is present, it is only a very small number of magnetic poles. Thereby, the magnetic short circuit in the proximity part 32 can be prevented, the magnetic short circuit in the unnecessary part which does not contribute to rotation of the motor 10 can be prevented, and high torque can be achieved.

  Further, the anti-air gap facing surface (here, the inward surface) facing the opposite side of the air gap in the permanent magnet 30 from the direction of the inclined surface 33a at the end of the permanent magnet 30 and the direction of the trapezoidal shape. The permanent magnet 30 is formed larger than the air gap facing surface (here, the outward surface). For this reason, the distance between each anti-air gap direction surface is short between the permanent magnets 30 adjacently provided in the circumferential direction. Therefore, the magnetic flux passing through the rotor core 22 can be shortened between the permanent magnets 30 provided adjacent to each other in the circumferential direction. This is because even if the shaft insertion hole 23 has a large diameter because it is necessary to insert a relatively large shaft into the rotor core 22 or when the bolt hole or the air hole is provided in the rotor core 22, they have a magnetic path. The merit is great in that the obstruction can be suppressed.

  In order to realize the magnitude relationship between the two main surfaces of the permanent magnet 30, the permanent magnet 30 does not necessarily have a trapezoidal shape on a surface substantially orthogonal to the rotating shaft 12.

  Here, the configuration of the gap 28 in relation to the proximity portion 32 will be described. The gap portion 28 is formed in a shape in which the peripheral edge portion of the proximity portion 32 and the rotor core 22 are opposed to each other through a gap larger than the width dimension of the magnet embedding recess 24 (see FIG. 3). More specifically, the gap 28 is bent from the end of the magnet-embedded recess 24 and extends toward the outer peripheral side of the rotor core 22. A corner-shaped outer corner 25a at the bent portion between the magnet-embedded recess 24 and the gap 28 is substantially coincident with the circumferential edge of the surface facing the anti-air gap of the permanent magnet 30, and the magnet-embedded recess The inner corner portion 25b having a protruding corner located at the bent portion between the gap 24 and the gap portion 28 is located at a position closer to the central portion in the circumferential direction of the permanent magnet 30 than the outer corner portion 25a. In other words, the gap 28 is formed in a portion facing the circumferential edge of the surface facing the anti-air gap of the permanent magnet 30 in a direction substantially orthogonal to the surface facing the anti-air gap of the permanent magnet 30. The void portion 28 is formed in such a manner that a part thereof exists. As a result, the distance L1 connecting the circumferential edge of the adjacent portion 32 in the direction opposite to the air gap and the rotor core 22 portion facing this through a gap is the thickness direction of the permanent magnet 30 in the magnet embedded recess 24. It is formed so that it may become more than the width dimension L2. Thereby, it is possible to increase the magnetic resistance as much as possible between the inclined surface 33a of the edge portion in the circumferential direction in the proximity portion 32 and the portion of the rotor core 22 that faces the slope 33a. Here, the width dimension L <b> 2 is substantially the same as the thickness dimension of the permanent magnet 30.

  According to the rotor 20 and the embedded magnet type motor 10 configured as described above, the permanent magnet 30 has anisotropy in which the easy axis of magnetization is inclined with respect to the thickness from the remote portion 34 toward the close portion 32. From the standpoint of magnet characteristics, the substantial thickness at the proximity portion 32 can be evaluated as a dimension along the direction of the inclined easy axis of magnetization. For this reason, the substantial thickness of the permanent magnet 30 can be increased at the proximity portion 32 that is close to the air gap and easily demagnetized in the permanent magnet 30, and local demagnetization of the permanent magnet 30 can be prevented. .

  In addition, as a result of measures for demagnetization as described above, the amount of rare elements used to increase the coercive force can be reduced, and the decrease in improvement in residual magnetic flux density can be suppressed. It can also contribute to efficiency.

  In particular, in the concentrated winding type motor 10 in which the coil 17 is wound around each tooth portion 16, the magnetic flux generated by the coil 17 flows to the adjacent tooth portion 16. Accordingly, the demagnetizing field acts more strongly on the proximity portion 32 of the permanent magnet 30 near the surface of the rotor 20. For this reason, when this form is applied to the concentrated winding type motor 10, the effect is great. Also, in sensorless motors and brushless motors that do not have a rotor rotational position detection unit, it is difficult to accurately grasp the rotor position and flow current, so a demagnetizing field tends to act on the permanent magnet. It can be said that the effect is great when applied to such a motor.

  In addition, the above effect is that, as in the conventional example, it is possible to take measures against demagnetization without relying on the contrivance of the material of the permanent magnet itself, the enlargement of the gap, or the combination of a plurality of permanent magnets. Although the merit is great, it does not necessarily exclude the combination with those configurations.

  Based on the above embodiment, more preferred embodiments and various modifications will be described. In addition, the same code | symbol is attached | subjected about the same component as the component already demonstrated in the following description, and the description is abbreviate | omitted.

  In the above-described embodiment, the permanent magnet has an anisotropy oriented so that the easy axis of magnetization in the proximity portion is inclined toward the far portion toward the anti-air gap side (here, the inner peripheral side). Also good. In this case, the demagnetizing field component substantially parallel to the easy magnetization axis is reduced in the adjacent portion, which is more effective from the viewpoint of preventing demagnetization.

  FIG. 4 is a partially enlarged view showing an end portion of the permanent magnet 130 according to the modification.

  In this modification, the proximity portion 132 of the permanent magnet 130 has an acute angle relaxation surface 133 b that intersects the inclined surface 133 a on the circumferential end side and the surface facing the anti-air gap of the permanent magnet 130 at a substantially right angle. It can be said that the acute angle relaxation surface 133b relaxes the acute angle portion formed by the anti-air gap facing surface of the permanent magnet 30 and the inclined surface 33a in the above-described embodiment to a substantially right angle.

  Thereby, when the permanent magnet 130 is formed, the proximity portion 32 can be easily filled with magnetic powder or the like, and the density can be increased. Therefore, the permanent magnet 130 can be easily manufactured, Chipping can be effectively prevented.

  In the case of this modification, it is preferable that the length dimension L3 of the inclined surface 133a between the main surfaces of the permanent magnet 130 is equal to or greater than the thickness dimension L4 of the permanent magnet 130. Thereby, since the substantial length dimension of the permanent magnet 130 can be made into the thickness dimension L4 of the permanent magnet 130 in the part along the slope 133a, demagnetization prevention can be aimed at effectively.

  Further, in this modified example, a protrusion 124 a that can abut on the intersecting portion of the acute angle relaxation surface 133 b and the surface facing the anti-air gap of the permanent magnet 130 is formed in the magnet embedding recess 124. Thereby, in a state where the permanent magnet 130 is accommodated and disposed in the magnet-embedded recess 124, the protrusion 124a abuts on the circumferential end of the permanent magnet 130, and the movement of the permanent magnet 130 in the magnet-embedded recess 124 is suppressed. It has become so.

  In this case, the dimension L1 in the above embodiment is considered as a distance connecting the rotor core 22 part facing the gap between the proximity part 132 and the protrusion 124a with a gap as a base point, which is equal to or larger than the width dimension L2. It is preferable to set so as to be.

  In the present modification, the angle formed between the anti-air gap facing surface of the permanent magnet 130 and the acute angle relaxation surface 133b may be an obtuse angle.

  FIG. 5 is a diagram showing a further modification of the modification shown in FIG.

  In this modified example, a portion of the magnet-embedded recess 124 that faces the short-side portion of the permanent magnet 130, that is, a circumferential end of the short-side portion, that is, a surface facing the air gap between the inclined surface 133 a and the permanent magnet 130. A reverse entry preventing projection 124b that can be contacted is also formed at the intersecting portion. In this modification, when the permanent magnet 130 is inserted into the magnet-embedded recess 124 with the air gap facing surface and the anti-air gap facing surface of the permanent magnet 130 being mistaken, the long side portion of the permanent magnet 130 is reversed. Since it abuts against the insertion preventing projection 124b, its insertion is hindered. For this reason, the reverse insertion of the permanent magnet 130 can be prevented.

  4 and 5, when the short side portion of the permanent magnet 130 is inward and the long side portion is outward, the inward surface of the permanent magnet 130 in the above description. A similar configuration can be applied with the outer surface and the outer surface reversed.

  Moreover, as the above permanent magnets 30 and 130, it is preferable to use rare earth sintered magnets, and it is more preferable to use Nd—Fe—B based magnets. This is because the magnetic energy product of the permanent magnets 30 and 130 can be increased and the size can be reduced.

  Moreover, when using a rare earth sintered magnet, the rare earth sintered magnet is molded and sintered at a high pressure. Therefore, it is preferable that the permanent magnets 30 and 130 have a simple flat plate shape. The permanent magnets 30 and 130 have shapes that can meet such demands.

  FIG. 6 is a diagram showing the relationship between the compression direction and the direction in which the orientation magnetic field is applied when the permanent magnet 130 is manufactured.

  The permanent magnet 130 has substantially the same shape in a direction along the rotation axis 12 on a surface substantially orthogonal to the rotation axis 12. For this reason, when the permanent magnet 130 is manufactured, an orientation magnetic field is applied in a direction substantially orthogonal to the rotation axis 12 (refer to an arrow P2) while being compressed in the direction of the rotation axis 12 (see arrow P1). Can be applied. The above is the application of the perpendicular magnetic field molding in which the compression direction and the orientation magnetic field are substantially orthogonal, which contributes to the improvement of the strength by increasing the density and the improvement of the magnetic properties such as the coercive force and the magnetic flux density.

  FIG. 7 is a partially enlarged view showing a modified example related to the gap 228.

  In this modification, a pair of gaps 228 are formed adjacent to both adjacent portions 32 of the permanent magnet 30. The pair of gaps 228 are formed to be gradually wider in the circumferential direction toward the air gap side, and a portion of the rotor core 22 surrounded by the pair of gaps 228, the permanent magnet 30, and the air gap is The width of the magnetic pole surface of the permanent magnet 30 is substantially the same. In other words, the spread angle θ2 of the core portion between the pair of gaps 228 is smaller than the spread angle θ1 of the magnetic pole surface portion of the permanent magnet 30 (magnetic pole portion) when viewed from the spread angle with respect to the rotating shaft 12. It has become.

  Thereby, magnetic flux can be collected by the magnetic pole center, and a torque improvement can be aimed at. Moreover, in such a form, since the space | gap part 228 width | variety becomes large, the magnetic flux by a demagnetizing field tends to pass the proximity | contact part 32 of the permanent magnet 30, and is easy to be demagnetized. Therefore, it is more effective to apply this configuration to such a form.

  FIG. 8 is a partially enlarged view showing another modified example related to the gap 328.

  In this modification, the gap portion 328 is formed in a shape in which the gap width in the circumferential direction decreases toward the air gap side. As a result, the demagnetizing field can be released at the portion of the air gap 328 on the air gap side where the air gap width is reduced, thereby further preventing demagnetization.

  FIG. 9 is a partially enlarged view showing another modified example related to the gap 228B shown in FIG.

  In this modified example, in the modified example shown in FIG. 7, a thin part 228Ba is provided in the gap 228B corresponding to the gap 228 so as to cross the gap 228B. The thin portion 228Ba has a role of improving the strength of the rotor core 22. Such a form may be used.

  FIG. 10 is a partially enlarged view showing a modified example related to the permanent magnet 430.

  In this modification, the permanent magnet 430 has a substantially rectangular shape on a surface substantially orthogonal to the rotating shaft 12 and does not have the inclined surface 33a. Even in this case, it can be evaluated that the substantial thickness of the permanent magnet is increased except for a portion of the proximity portion 432 of the permanent magnet 430 that is added in excess of the portion corresponding to the slope 33a. In addition, regarding the portion added in excess of the portion corresponding to the inclined surface 33a in the proximity portion 432 of the permanent magnet 430, the demagnetizing field component along the easy axis direction is considered to be reduced by the inclination of the easy axis. Therefore, the demagnetization resistance is also improved.

  In the above-described embodiment and the modification, the description has been given in the form of the inner rotor in which the rotor 20 is present on the inner peripheral side of the stator 14, but the outer rotor may be in the form of an outer rotor around the stator.

  FIG. 11 is a cross-sectional view showing a modification applied to the outer rotor. In the rotor 620 shown in FIG. 11, the rotor core 622 is provided with a plurality of magnetic pole portions 631. Each magnetic pole portion 631 has a configuration in which two permanent magnets 630 are embedded in the magnet-embedded recess 624 in a form that is substantially V-shaped on a surface substantially orthogonal to the rotating shaft 12. That is, the number of permanent magnets 630 per one magnetic pole part 631 is two. In this way, when the magnetic pole part 631 is composed of a plurality of permanent magnets 630, the easy axis of magnetization of the proximity part 632 which is one end part close to the air gap among the permanent magnets 630 located on the magnetic pole end side. What is necessary is just to show the anisotropy which inclines with respect to the thickness direction.

  In addition, each structure demonstrated in the said embodiment and each modification can be suitably combined unless it mutually contradicts.

It is sectional drawing which shows the embedded magnet type motor which concerns on embodiment. It is sectional drawing which shows the rotor in an embedded magnet type motor same as the above. It is the elements on larger scale which show the edge part of a permanent magnet. It is the elements on larger scale which show the edge part of the permanent magnet which concerns on a modification. It is the elements on larger scale which show the further modification of the modification shown in FIG. It is a figure which shows the relationship between the compression direction with respect to a permanent magnet, and the application direction of an orientation magnetic field. It is the elements on larger scale which show the space | gap part which concerns on a modification. It is the elements on larger scale which show the space | gap part which concerns on a modification. It is the elements on larger scale which show the space | gap part which concerns on a modification. It is the elements on larger scale which show the permanent magnet which concerns on a modification. It is sectional drawing which shows the modification applied to the outer rotor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Embedded magnet type motor 12 Rotating shaft 14 Stator 17 Coil 20,620 Rotor 22,622 Rotor core 24,124,624 Magnet embedding recessed part 28,228,228B, 328 Gap part 30,130,430,630 Permanent magnet 32,132 , 432, 632 Proximity portion 33a, 133a Slope 34 Distant portion 124a Protrusion 133b Acute angle relaxation surface A Easy axis of magnetization

Claims (18)

A rotor (20, 620) facing the stator (14) via a substantially cylindrical air gap having a central axis substantially parallel to the rotational axis (12),
A rotor core (22, 622) formed in a substantially cylindrical shape;
A plurality of magnetic pole portions embedded in the rotor core in a manner along the circumferential direction around the rotation axis;
With
The magnetic pole portion is formed in a substantially plate shape, near the end of the magnetic pole, near the air gap (32, 132, 432, 632) and closer to the magnetic pole center than the proximity portion, It is embedded in a magnet embedded recess (24, 124, 624) formed in the rotor core in a form having a remote portion (34) far from the air gap, and an easy magnetization axis (from the remote portion toward the close portion) A rotor in which A) has permanent magnets (30, 130, 430, 630) exhibiting anisotropy inclined with respect to the thickness direction. The rotor according to claim 1,
The permanent magnet (30, 130, 430, 630) is a rotor, which is a rare earth sintered magnet. The rotor according to claim 1 or 2, wherein
The permanent magnet (30, 130, 430, 630) is a rotor that is an Nd-Fe-B magnet. The rotor according to any one of claims 1 to 3,
The permanent magnet (130) has a surface substantially orthogonal to the rotation axis that has substantially the same shape in the direction along the rotation axis, and is compressed in the direction (P1) of the rotation axis. A rotor formed by applying an orientation magnetic field in a direction (P2) substantially perpendicular to the direction. The rotor according to any one of claims 1 to 4,
The permanent magnet (30, 130, 430, 630) is a rotor having anisotropy in which an easy axis (A) is radially oriented. The rotor according to any one of claims 1 to 5,
In the permanent magnet (30, 130, 430, 630), the axis of easy magnetization (A) in the proximity portion (32, 132, 432, 632) is inclined toward the far portion (34) side toward the stator side. A rotor having anisotropy oriented to: The rotor according to any one of claims 1 to 6,
The proximity portion (32, 132, 632) has a slope (33a, 133a) substantially parallel to the orientation direction of the easy axis (A) in the proximity portion. The rotor according to any one of claims 1 to 7,
The said permanent magnet (30,130,630) is a rotor formed in the substantially trapezoid shape in the surface substantially orthogonal to the said rotating shaft. The rotor according to claim 7 or claim 8,
The proximity portion (132) has an acute angle relaxation surface (133b) that intersects at an approximately right angle or an obtuse angle with a slope (133a) of the proximity portion and a main surface of the permanent magnet (130). The rotor according to claim 9, wherein
A rotor in which a protrusion (124a) capable of contacting the intersection of the acute angle relaxation surface of the adjacent portion and the main surface of the permanent magnet is formed in the magnet-embedded recess (124). The rotor according to claim 9 or 10, wherein
The rotor has a length dimension (L3) of a slope of the adjacent portion between both main surfaces of the permanent magnet that is equal to or greater than a thickness dimension (L4) of the permanent magnet. The rotor according to any one of claims 1 to 11,
The rotor in which both main surfaces of the permanent magnet (30, 130, 430, 630) are substantially in contact with the inner surface of the magnet-embedded recess (24, 124, 624). The rotor according to any one of claims 1 to 12,
Of the permanent magnets (30, 130, 630), the surface facing the air gap is larger than the surface facing the air gap. The rotor according to any one of claims 1 to 13,
The rotor core has a gap (28, 228, 228B, 328) adjacent to the adjacent portion. The rotor according to claim 14, wherein
The gap (28, 228, 228B, 328) has a shape in which the edge of the adjacent portion and the rotor core are opposed to each other via a gap (L1) that is equal to or larger than the width dimension (L2) of the magnet-embedded recess. Formed rotor. A rotor according to claim 14 or claim 15, wherein
A pair of the gap portions (228) is formed adjacent to both magnetic pole ends of the magnetic pole portion,
A rotor in which a spread angle (θ2) of a core portion provided between the pair of gap portions with respect to the rotation axis is smaller than a spread angle (θ1) of the magnetic pole portion with respect to the rotation axis. The rotor according to any one of claims 14 to 16, wherein
The said space | gap part (328) is a rotor currently formed in the shape where a space | gap width becomes small toward the said air gap side. A rotor (20, 620) according to any of claims 1 to 17,
A coil (17) facing the rotor via a substantially cylindrical air gap;
Embedded magnet type motor equipped with

Images