JP2006211753A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor that can suppress the generation of noise and vibration by reducing cogging torque. <P>SOLUTION: The brushless motor 10 of an axial gap type comprises a back yoke 80 in a stator unit 30 and salient poles 82 on the back yoke 80 wound with a stator coil 70. The salient pole 82 is formed into a chevron shape so as to gradually approximate a rotor magnet 24 as progressing toward the center side (Rc side) in the motor rotative direction from the tip side (Rf side) in the motor rotative direction, and to be apart from the rotor magnet 24 as progressing toward the rear end side (Rr side) in the motor rotative direction from the center side (Rc side) in the motor rotative direction. Thereby, since a suction force or a repulsive force acting between the rotor magnet 24 and the back yoke 80 is gradually increased and decreased, the cogging torque is reduced, and the generation of noise and vibration can be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a brushless motor, and more particularly to an axial gap type brushless motor in which a plurality of salient poles are formed on a stator core so as to face a rotor magnet and a motor rotation axis direction.

  2. Description of the Related Art Conventionally, a so-called axial gap type brushless motor in which a rotor and a stator are arranged so as to face each other in the motor rotation axis direction is known. Some brushless motors of this type include a stator core in a stator and a plurality of salient poles around which a stator coil is wound around a motor rotation shaft of the stator core (see, for example, Patent Document 1).

  The configuration of the stator core in this type of brushless motor will be briefly described with reference to FIGS. 12 and 13. The stator core 180 provided in the conventional brushless motor is shown in FIGS. 12 (a) and 12 (b). Thus, the sectional shape of the salient pole 182 when the salient pole 182 is cut along the motor rotation direction R is rectangular.

Further, as shown in FIGS. 13A and 13B, in the conventional brushless motor, the rotor magnet 224 side of the salient pole 282 protrudes more toward the rotor magnet 224 than the air core portion 272 of the stator coil 270. In addition, some of the stator coil 270 is configured to cover a part of the end surface 270a on the rotor magnet 224 side. At this time, the cross-sectional shape of the end 282a that protrudes toward the rotor magnet 224 from the air core 272 of the stator coil 270 of the salient pole 282 is rectangular when the salient pole 282 is cut along the motor rotation direction R. It was.
Japanese Utility Model Publication No. 6-70476 (FIGS. 1 and 9)

  However, in the prior art shown in FIG. 12, the salient pole 182 has a rectangular cross section, and therefore, as shown in FIG. 12 (b), a location where the gap between the rotor magnet 124 and the stator core 180 is large (reference numeral). A place indicated by P1 and a place having a small gap (a place indicated by reference sign P2) are alternately present.

  When the rotor 120 is rotated by energization of the stator coil 170, the magnetic poles of the rotor magnet 124 are repeatedly switched so that the gap between the stator core 180 and the stator core 180 is small and large. Become.

  At this time, when the gap between the rotor magnet 124 and the stator core 180 is large, the magnetic flux density between the rotor magnet 124 and the stator core 180 is low, and when the gap between the rotor magnet 124 and the stator core 180 is small, the rotor magnet 124 and the stator core. The magnetic flux density between 180 increases.

  Therefore, when the rotor 120 is rotated by energization of the stator coil 170, the magnetic flux density of the rotor magnet 124 is repeated so that the magnetic flux density is rapidly switched between the low state and the high state. The attractive / repulsive force acting between the rotor magnet 124 and the stator core 180 also suddenly increases or decreases.

  As described above, when the attractive / repulsive force acting between the rotor magnet 124 and the stator core 180 suddenly increases or decreases and the magnetic energy changes rapidly, the cogging torque (torque fluctuation due to the rotation angle) increases. There arises a problem that noise and vibration increase.

  Similarly, in the prior art shown in FIG. 13, the cross-sectional shape of the end portion 282a that protrudes toward the rotor magnet 224 from the air core portion 272 of the stator coil 270 of the salient pole 282 is rectangular. When 220 is rotating, the magnetic flux density of the rotor magnet 224 is repeated so that the magnetic flux density is switched between a low state and a high state rapidly.

  As a result, as described above, the attractive / repulsive force acting between the rotor magnet 224 and the stator core 280 suddenly increases / decreases and the magnetic energy suddenly changes, so that the cogging torque increases, noise and The problem of increased vibrations arises.

  The present invention has been made in view of the above problems, and its object is to suppress the generation of noise and vibration by reducing the cogging torque with a simple configuration without using a special configuration. It is to provide a brushless motor.

  In order to solve the above problem, a brushless motor according to claim 1 is configured so that a rotor having a rotor magnet in which a plurality of magnetic poles are formed around a motor rotation axis, and the rotor magnet face each other in the motor rotation axis direction. And a stator having a stator core with a stator coil wound around each of the salient poles, and the rotor magnet of the salient poles. The side gradually approaches the rotor magnet from the front side in the motor rotation direction toward the center side in the motor rotation direction, and gradually moves away from the rotor magnet from the center side in the motor rotation direction toward the rear end side in the motor rotation direction. It is characterized by being formed in a Yamagata shape.

  Thus, according to the brushless motor of the first aspect, the rotor magnet side of the salient pole gradually approaches the rotor magnet from the front end side in the motor rotation direction toward the center side in the motor rotation direction, and at the center side in the motor rotation direction. Is formed in a mountain shape so as to gradually move away from the rotor magnet toward the rear end side in the motor rotation direction, so that when the rotor is rotated by energization of the stator coil, magnetic flux is generated at each magnetic pole of the rotor magnet. The state where the density is low and the state where the density is high are gradually switched.

  Accordingly, the attractive / repulsive force acting between the rotor magnet and the stator core also gradually increases and decreases, and the change in magnetic energy becomes gradual. Thereby, since cogging torque can be reduced, it becomes possible to suppress generation of noise and vibration.

  At this time, as in the brassless motor according to claim 2, more preferably, the front end side in the motor rotation direction of the salient pole on the rotor magnet side gradually increases from the front end side in the motor rotation direction toward the central side in the motor rotation direction. It consists of a flat or curved inclined surface that approaches the rotor magnet, and gradually moves from the rotor magnet toward the rear end side of the motor rotation direction from the motor rotation direction center side of the motor rotation direction on the rotor magnet side of the salient pole. It consists of a flat or curved inclined surface that moves away.

  With this configuration, when the rotor is rotated by energizing the stator coil, it is more reliable that the magnetic flux density of each magnetic pole of the rotor magnet is gradually switched between the low magnetic flux density state and the high magnetic flux state. Can be.

  Further, as in the brushless motor according to claim 3, more preferably, the top of the salient pole on the rotor magnet side center side in the motor rotation direction is parallel to the end surface on the stator side of the rotor magnet. A surface is formed, and this top surface is formed so as to gradually become wider from the inner side to the outer side in the motor radial direction.

  That is, in a brushless motor in which the rotor and the stator are arranged so as to oppose each other in the motor rotation axis direction, the speed at which the magnetic poles of the rotor magnet pass on the salient pole is faster on the outer side than on the inner side in the motor radial direction Therefore, as in the brushless motor according to claim 3, when the top surface of the salient pole is formed so as to gradually increase from the inner side to the outer side in the motor radial direction, Thus, the timing at which the magnetic pole of the rotor magnet passes through the top surface of the salient pole can be matched. As a result, the cogging torque can be reduced more stably.

  Note that, as in the brushless motor according to the fourth aspect, the rotor magnet side of the salient pole may be configured to be located inside the air core portion of the stator coil.

  If comprised in this way, since the protrusion amount to the rotor magnet side of a salient pole can be suppressed, the gap of a rotor magnet and a stator core can be made small. Thereby, the magnetic flux density between the rotor magnet and the stator core can be increased, and the motor torque can be improved.

  Further, as in the brushless motor according to claim 5, the rotor magnet side of the salient pole protrudes to the rotor magnet side from the air core portion of the stator coil, and a part of the end surface of the stator coil on the rotor magnet side is formed. You may be comprised so that it may cover.

  With this configuration, the rotor coil side of the salient pole configured to protrude to the rotor magnet side from the air core portion of the stator coil and to cover a part of the end surface on the rotor magnet side of the stator coil. The magnetic flux of the rotor magnet can be taken into the stator coil side. Thereby, the magnetic flux density between the rotor magnet and the stator core can be increased, and the motor torque can be improved.

  Further, as in the brushless motor according to claim 6, the stator includes a connection terminal unit for connecting the terminal portions of the plurality of stator coils, and the connection terminal unit, the plurality of stator coils, and the stator core are integrally formed of a resin member. It may be unitized by molding.

  If comprised in this way, at the time of the assembly operation of a brushless motor, it will become possible to assemble | attach the stator which united the connection terminal unit, the several stator coil, and the stator core to the motor main body easily.

  Further, as in the brushless motor according to the seventh aspect, the stator may be integrally formed with a resin member with an external mounting stay by molding.

  With this configuration, when the stator is formed by integrally molding the connection terminal unit, the plurality of stator coils, and the stator core with a resin member, an external mounting stay is simultaneously formed on the stator. It is not necessary to separately mold the mounting stay. As a result, the number of manufacturing steps can be reduced as compared with the conventional case, and the increase in the number of parts can be prevented, so that the manufacturing cost can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that members, arrangements, and the like described below do not limit the present invention, and it goes without saying that various modifications can be made in accordance with the spirit of the present invention.

First, the configuration of a brushless motor according to an embodiment of the present invention will be described.
A brushless motor 10 according to an embodiment of the present invention is suitably applied to, for example, a brushless fan motor device for cooling a radiator of a passenger car, for example, as shown in FIG. A stator unit 30 as a stator, a circuit unit 40, and a back frame 50 are included.

  The rotor 20 includes a rotor yoke 22 configured in a disk shape, and an annular rotor magnet 24 is fixed to a flat surface portion 22a of the rotor yoke 22 on the stator unit 30 side. In the rotor magnet 24, N poles and S poles are alternately formed around the motor rotation axis L (for example, eight poles are formed).

  An annular shaft support portion 22b is formed at the center of the rotor yoke 22, and a rotating shaft 26 is fitted into the shaft support portion 22b. The rotating shaft 26 is rotatably supported by a bearing member 32 provided in a stator unit 30 described later, and a fan (not shown) is fixed to the tip of the rotating shaft 26 by a fixing tool such as a screw. It is like that.

  As shown in FIGS. 1 and 2, the stator unit 30 includes a connection terminal unit 60, a stator coil 70, and a back yoke 80 as a stator core. The stator unit 30 of the present embodiment is an integrated unit obtained by further molding a pre-molded connection terminal unit 60, a stator coil 70, and a back yoke 80, and is configured in a predetermined shape. ing.

  That is, the configuration of the molded stator unit 30 will be described. On the motor rotation shaft L of the stator unit 30, a hole 30a for inserting the rotation shaft 26 is formed. Around the periphery, bearing support portions 30b for supporting the bearing member 32 are formed at two positions separated in the motor rotation axis L direction.

  As shown in FIG. 2, an external mounting stay 30 c extending in the motor radial direction is formed at a position near the boundary of the stator coil 70 in the motor radial direction outer portion of the stator unit 30. The external mounting stay 30c is integrally formed of a resin member when the stator unit 30 is molded.

  Further, as shown in FIG. 1, a connection terminal unit 60 is disposed on the rotor 20 side of the stator unit 30 so as to face the rotor 20, and around the motor rotation axis L of the connection terminal unit 60. A plurality of stator coils 70 are provided so as to face the rotor magnet 24 in the motor rotation axis L direction. The stator coil 70 of this embodiment is connected in a Y shape by a connection terminal unit 60, and a back yoke 80 is integrally connected to the connection terminal unit 60.

  As shown in FIG. 3, the connection terminal unit 60 of this embodiment is a substantially disk-shaped member in which the connection terminal frame 62 and the resin member are integrated by molding the connection terminal frame 62 (bus bar). is there. FIG. 3 is a diagram illustrating a configuration of the connection terminal unit 60 at a stage before being molded into the stator unit 30. As shown in FIG. 3, a hole 60a penetrating in the motor rotation axis direction is formed in the central portion of the connection terminal unit 60, and the inner annular molded portion 60b formed around the hole 60a includes: The connection terminal frame 62 is molded.

  The connection terminal frame 62 used for the connection terminal unit 60 includes a U-phase frame 62u, a V-phase frame 62v, a W-phase frame 62w, and a common frame 62c. Each of the U-phase frame 62u, the V-phase frame 62v, the W-phase frame 62w, and the common frame 62c is formed by bending an elongated conductive flat plate member into an arc shape around the motor rotation axis.

  Each of the U-phase frame 62u, the V-phase frame 62v, and the W-phase frame 62w is connected for connection to the terminal portion of the stator coil 70 (see FIG. 2) of each phase of the U phase, V phase, and W phase. A terminal 64 is formed. Further, the common frame 62c is formed with connection terminals 66 for connecting terminal portions which are neutral points of the U-phase, V-phase, and W-phase stator coils 70, respectively.

  A plurality of notches 60c penetrating in the plate thickness direction are formed in the resin molded portion where the connection terminals 64 and 66 are located on the radially outer side of the inner annular molded portion 60b formed in the connection terminal unit 60. . In the present embodiment, by providing the notched portion 60c in the resin molded portion of the connection terminal unit 60 in this way, the connection terminals 64 and 66 project from the inner annular molded portion 60b outward in the radial direction. , 66 and the terminal portion of the stator coil 70 can be connected to each other by spot welding or the like through the notch 60c.

  A plurality of stator coil fixing portions 60e for fixing the stator coil 70 are formed on the outer annular molded portion 60d formed radially outside the inner annular molded portion 60b of the connection terminal unit 60. Further, a salient pole insertion portion 60f penetrating in the plate thickness direction is formed inside the stator coil fixing portion 60e. In this embodiment, the salient pole insertion portion 60f has a back yoke 80 described in detail later. The salient pole 82 can be inserted. Further, an insulating wall 60g is provided between the stator coil fixing portion 60e and the stator coil fixing portion 60e so that adjacent stator coils in the stator coil 70 do not contact each other.

  As shown in FIG. 4A, around the motor rotation axis L of the back yoke 80, there are a plurality of salient poles 82 (eight in this embodiment) so as to face the rotor magnet 24 in the motor rotation axis L direction. Is formed. A stator coil 70 is wound around the salient pole 82 via a stator coil fixing portion 60e of the connection terminal unit 60 (see FIGS. 2 and 3).

  Here, the configuration of the back yoke 80 of the present embodiment will be described with reference to FIG. 4B. The rotor magnet 24 side of the salient pole 82 is from the motor rotation direction front end side (Rf side) to the motor rotation direction center side. (Rc side) gradually approaches the rotor magnet 24 and forms a mountain shape so that it gradually moves away from the rotor magnet 24 toward the motor rotation direction rear end side (Rr side) from the motor rotation direction center side (Rc side). Formed

  That is, the salient pole 82 has a planar shape that gradually approaches the rotor magnet 24 from the front end side (Rf side) in the motor rotation direction toward the central side (Rc side) in the motor rotation direction. A first inclined surface 84 is formed, and the rear end side (Rr side) of the salient pole 82 in the motor rotation direction is directed from the central side (Rc side) in the motor rotation direction to the rear end side (Rr side) in the motor rotation direction. Accordingly, a planar second inclined surface 86 that gradually moves away from the rotor magnet 24 is formed.

  Further, a flat top surface 88 is formed on the center side (Rc side) of the salient pole 82 on the rotor magnet 24 side in the motor rotation direction so as to be parallel to the end surface 24a on the stator unit 30 side of the rotor magnet 24. Yes. As shown in FIG. 4A, the top surface 88 gradually increases in width from the inner side (Xi side) to the outer side (Xo side) in the motor radial direction (the width in this case is the motor rotation direction R of the top surface 88). It is formed so that the length of

  Further, in this embodiment, as shown in FIG. 4B, when the stator coil 70 is wound around the salient pole 82, the top surface 88 formed on the rotor magnet 24 side of the salient pole 82 is 70 is located inside the air core portion 72.

  As shown in FIG. 1, the circuit unit 40 includes a heat sink 42 and a circuit board 44. The heat sink 42 is disposed on the opposite side of the stator unit 30 from the rotor 20, and the circuit board 44 is provided on the opposite side of the heat sink 42 from the stator unit 30. The circuit board 44 is provided with a driver IC 44a and other electronic components, and the driver IC 44a is connected to the connection terminal unit 60 by a wiring member 44b. The circuit unit 40 is covered with a back frame 50 on the side opposite to the stator unit 30.

  Next, the operation of the brushless motor having the above configuration will be described.

  According to the brushless motor 10 according to the embodiment of the present invention, the rotor magnet 24 side of the salient pole 82 gradually increases from the motor rotation direction front end side (Rf side) toward the motor rotation direction center side (Rc side). 24, and is formed in a mountain shape so as to gradually move away from the rotor magnet 24 from the motor rotation direction center side (Rc side) toward the motor rotation direction rear end side (Rr side). Thus, when the rotor 20 is rotating, the magnetic flux density of each of the magnetic poles of the rotor magnet 24 is gradually switched between a low state and a high state.

  Accordingly, the attractive / repulsive force acting between the rotor magnet 24 and the back yoke 80 also gradually increases and decreases, and the change in magnetic energy becomes gradual. Thereby, since cogging torque can be reduced, it becomes possible to suppress generation of noise and vibration.

  Further, in this embodiment, the salient pole 82 gradually approaches the rotor magnet 24 toward the front end side (Rf side) in the motor rotation direction from the front end side (Rf side) in the motor rotation direction toward the central side (Rc side) in the motor rotation direction. A flat first inclined surface 84 is formed, and the salient pole 82 is directed to the rear end side (Rr side) in the motor rotation direction from the central side (Rc side) in the motor rotation direction to the rear end side (Rr side) in the motor rotation direction. Accordingly, a planar second inclined surface 86 that gradually moves away from the rotor magnet 24 is formed.

  With this configuration, when the rotor 20 is rotated by energization of the stator coil 70, the magnetic flux density of the rotor magnet 24 is gradually switched between a low magnetic flux density state and a high magnetic flux density state. It can be made more reliable.

  Further, in the present embodiment, the top surface 88 having a planar shape is parallel to the end surface 24a on the stator unit 30 side of the rotor magnet 24 on the motor rotation direction center side (Rc side) of the salient pole 82 on the rotor magnet 24 side. The top surface 88 is formed so as to gradually become wider from the inner side (Xi side) to the outer side (Xo side) in the motor radial direction.

  That is, as in the present embodiment, in the brushless motor 10 in which the rotor 20 and the stator unit 30 are arranged so as to face each other in the motor rotation axis L direction, the outer side (Xo side) than the inner side (Xi side) in the motor radial direction. This increases the speed at which the magnetic poles of the rotor magnet 24 pass over the salient poles 82 (the distance is longer). At this time, when the top surface 88 of the salient pole 82 is formed so as to gradually increase from the inner side (Xi side) to the outer side (Xo side) as in this embodiment, the motor diameter The timing at which the magnetic poles of the rotor magnet 24 pass through the top surface 88 of the salient pole 82 can be matched between the inner side (Xi side) and the outer side (Xo side). As a result, the cogging torque can be reduced more stably.

  Further, as in the present embodiment, when the salient pole 82 is configured so that the rotor magnet 24 side is positioned inside the air core portion 72 of the stator coil 70, the salient pole 82 projects to the rotor magnet 24 side. Since the amount can be suppressed, the gap between the rotor magnet 24 and the back yoke 80 can be reduced. Thereby, the magnetic flux density between the rotor magnet 24 and the back yoke 80 can be increased, and the motor torque can be improved.

  Further, in this embodiment, the stator unit 30 is formed as a single unit by molding the connection terminal unit 60, the plurality of stator coils 70, and the back yoke 80, so that when the brushless motor is assembled, The connection terminal unit 60, the plurality of stator coils 70, and the back yoke 80 can be prevented from being scattered. Therefore, the stator unit 30 can be easily assembled to the motor body.

  Furthermore, in this embodiment, when the stator unit 30 is formed by integrally molding the connection terminal unit 60, the plurality of stator coils 70, and the back yoke 80 with a resin member, the external mounting stay 30c is provided on the stator unit 30. Since they are formed at the same time, it is possible to eliminate the need for separately forming the external mounting stay 30c. As a result, the number of manufacturing steps can be reduced as compared with the conventional case, and the increase in the number of parts can be prevented, so that the manufacturing cost can be reduced.

  In the present embodiment, since the connection terminal unit 60 is formed by molding the connection terminal frame 62, the shape and position of the connection terminal frame 62 can be fixed by a resin member. Thereby, the handling of the connection terminal unit 60 can be facilitated during the assembly operation of the brushless motor 10.

  Further, in the present embodiment, as shown in FIG. 2, the external mounting stay 30c is formed in the vicinity of the boundary of the plurality of stator coils 70 in the stator unit 30, so that the resin is formed at the position where the external mounting stay 30c is formed. The external mounting stay 30c can be formed without joining. Therefore, the external appearance of the external mounting stay 30c can be improved, and the strength of the external mounting stay 30c can be ensured.

The embodiment of the present invention can be modified as follows.
(1) In the above embodiment, the first inclined surface 84 and the second inclined surface 86 formed on the salient poles 82 are each formed in a planar shape, but as shown in FIG. The 2nd inclined surface 86 may be formed in the convex curve shape. Moreover, the 1st inclined surface 84 and the 2nd inclined surface 86 may be formed in the concave curved surface shape. Furthermore, one of the first inclined surface 84 and the second inclined surface 86 may be planar, and the other may be curved.

  (2) In the above embodiment, the top surface 88 formed on the center side in the motor rotation direction on the rotor magnet 24 side of the salient pole 82 is formed so as to gradually become wider from the inner side to the outer side in the motor radial direction. However, as shown in FIG. 6, the width of the top surface 88 (the width in this case indicates the length of the top surface 88 in the motor rotation direction R) is from the inner side (Xi side) to the outer side (Xo side) of the motor radial direction. It may be formed so as to become constant as it goes to.

  (3) In the above embodiment, the salient pole 82 has the top surface 88 on the center side (Rc side) in the motor rotation direction on the rotor magnet 24 side. However, as shown in FIG. The curved first inclined surface 84 and the curved second inclined surface 86 may be configured to be continuous in a mountain shape.

  (4) The salient poles 82 may be formed in a pyramid shape (triangular pyramid shape) as shown in FIG.

  (5) In the above embodiment, the top surface 88 of the salient pole 82 is formed so as to extend from the inner side (Xi side) end of the salient pole 82 in the motor radial direction toward the outer side (Xo side). As shown, the salient pole 82 may be formed in a quadrangular pyramid shape, and the top surface 88 of the salient pole 82 may be formed at an intermediate portion in the motor radial direction X.

  (6) In the above embodiment, the first inclined surface 84 and the second inclined surface 86 of the salient pole 82 are configured to be continuous with the upper end surface 80a of the back yoke 80. However, as shown in FIG. The first inclined surface 84 and the second inclined surface 86 of the pole 82 may be formed on the upper end surface 80a of the back yoke 80 via the vertical surface 80b.

  That is, the front end side (Rf side) in the motor rotation direction and the rear end side (Rr side) in the motor rotation direction on the rotor magnet 24 side of the salient poles 82 may be chamfered. Thus, the salient pole 82 as a whole may not be chevron-shaped, but the end 82a on the rotor magnet 24 side may be chevron-shaped. In this way, when the stator coil 70 is wound directly around the salient pole 82, the stator coil 70 can be wound around the vertical surface 80b.

  (7) In the above embodiment, the salient pole 82 is formed so that the rotor magnet 24 side is located inside the air core portion 72 of the stator coil 70. However, as shown in FIG. The magnet 24 side may be configured in an umbrella shape so as to protrude from the air core portion 72 of the stator coil 70 to the rotor magnet 24 side and to cover a part of the end surface 70a of the stator coil 70 on the rotor magnet 24 side. .

  With this configuration, the magnetic flux of the rotor magnet 24 can be taken into the stator coil 70 side at the end portion 82a on the rotor magnet 24 side of the salient pole 82 configured in an umbrella shape as described above. Thereby, the magnetic flux density between the rotor magnet 24 and the back yoke 80 can be increased, and the motor torque can be improved.

FIG. 1 is a diagram showing a configuration of a brushless motor according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a stator according to an embodiment of the present invention. FIG. 3 is a diagram showing a configuration of a connection terminal unit according to an embodiment of the present invention. FIG. 4A is a perspective view showing a configuration of a back yoke according to an embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along line AA. Fig.5 (a) is a perspective view which shows the structure of the back yoke which concerns on a 1st modification, FIG.5 (b) is a BB sectional drawing. FIG. 6A is a perspective view showing a configuration of a back yoke according to a second modification, and FIG. 6B is a cross-sectional view taken along the line CC. Fig.7 (a) is a perspective view which shows the structure of the back yoke which concerns on a 3rd modification, FIG.7 (b) is DD sectional view taken on the line. FIG. 8A is a perspective view showing a configuration of a back yoke according to a fourth modification, and FIG. 8B is a cross-sectional view taken along the line EE. FIG. 9A is a perspective view illustrating a configuration of a back yoke according to a fifth modification, and FIG. 9B is a cross-sectional view taken along the line FF. FIG. 10A is a perspective view illustrating a configuration of a back yoke according to a sixth modification, and FIG. 10B is a cross-sectional view taken along the line GG. FIG. 11A is a perspective view showing a configuration of a back yoke according to a seventh modification, and FIG. 11B is a cross-sectional view taken along the line HH. 12A is a perspective view showing a configuration of a back yoke according to a conventional example, and FIG. 12B is a cross-sectional view taken along the line II. FIG. 13A is a perspective view showing a configuration of a back yoke according to a conventional example, and FIG. 13B is a cross-sectional view taken along the line JJ.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Brushless motor, 20 ... Rotor, 22 ... Rotor yoke, 22a ... Planar part, 22b ... Shaft support part, 24 ... Rotor magnet, 24a ... End face, 26 ... Rotating shaft, 30 ... Stator unit (stator), 30a ... Hole , 30b ... bearing support portion, 30c ... external mounting stay, 32 ... bearing member, 40 ... circuit unit, 42 ... heat sink, 44 ... circuit board, 44a ... driver IC, 44b ... wiring member, 50 ... back frame, 60 ... connection Terminal unit, 60a ... hole, 60b ... inner annular molded part, 60c ... notched part, 60d ... outer annular molded part, 60e ... stator coil fixing part, 60f ... salient pole insertion part, 60g ... insulating wall, 62 ... connection terminal Frame, 62c ... Common frame, 62u ... U phase frame, 62v ... V phase frame, 62w ... W phase frame, 4, 66 ... connection terminal, 70 ... stator coil, 70a ... end face, 72 ... air core part, 80 ... back yoke (stator core), 80a ... upper end face, 82 ... salient pole, 82a ... end part, 84 ... first slope Surface (inclined surface), 86 ... second inclined surface (inclined surface), 88 ... top surface

Claims (7)

A rotor having a rotor magnet having a plurality of magnetic poles formed around a motor rotation axis;
A stator core having a plurality of salient poles formed around the motor rotation axis so as to face the rotor magnet and the motor rotation axis, and a stator having a stator coil wound around each of the salient poles. Brushless motor
The rotor magnet side of the salient pole gradually approaches the rotor magnet as it goes from the front end side in the motor rotation direction to the center side in the motor rotation direction, and gradually goes from the center side in the motor rotation direction toward the rear end side in the motor rotation direction. A brushless motor, wherein the brushless motor is formed in a mountain shape so as to move away from the rotor magnet. The leading end side of the salient pole on the rotor magnet side in the motor rotation direction is composed of a flat or curved inclined surface that gradually approaches the rotor magnet as it goes from the leading end side in the motor rotation direction to the central side in the motor rotation direction.
The rear end side of the salient pole on the rotor magnet side in the motor rotation direction is a flat or curved inclined surface that gradually moves away from the rotor magnet as it goes from the motor rotation direction center side to the motor rotation direction rear end side. The brushless motor according to claim 1, wherein the motor is a brushless motor. A flat top surface is formed on the center side of the salient pole on the rotor magnet side in the motor rotation direction so as to be parallel to the end surface on the stator side of the rotor magnet,
The brushless motor according to claim 1, wherein the top surface is formed so as to gradually increase in width from the inner side to the outer side in the motor radial direction.   The brushless motor according to any one of claims 1 to 3, wherein the rotor magnet side of the salient pole is located inside an air core portion of the stator coil.   The rotor magnet side of the salient pole is configured to protrude to the rotor magnet side from the air core portion of the stator coil and to cover a part of the end surface of the stator coil on the rotor magnet side. The brushless motor according to claim 1, wherein the motor is a brushless motor.   The stator includes a connection terminal unit for connecting terminal portions of the plurality of stator coils, and is unitized by integrally molding the connection terminal unit, the plurality of stator coils, and the stator core with a resin member. The brushless motor according to any one of claims 1 to 5, wherein the brushless motor is provided.   The brushless motor according to claim 6, wherein an external mounting stay is integrally formed of a resin member on the stator by the molding.

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