WO2023248777A1

WO2023248777A1 - Brushless motor

Info

Publication number: WO2023248777A1
Application number: PCT/JP2023/020911
Authority: WO
Inventors: 渉横山; 一平鈴木; 肇寺崎; 佑亮西澤
Original assignee: 日立Astemo株式会社
Priority date: 2022-06-22
Filing date: 2023-06-06
Publication date: 2023-12-28

Abstract

This brushless motor has: a rotor 5 having a rotor core 9 to which a motor output shaft 4 is fixed; a permanent magnet 11 having a body 11a disposed inside each holding hole 10 formed in the outer circumference of the rotor core and a projection portion 11b projecting in the axial direction from one end opening portion 10a of each holding hole; magnetic sensors 22a to 22c each disposed so as to face the projection portion from the axial direction and detecting a magnetic flux component of the permanent magnet in the rotational axis direction; and two extending portions 12, 12 provided on both side surfaces of the projection portion in the circumferential direction of the rotor core. The extending portions are each formed so that facing one end surface 12a and the other end surface 12b of the facing extending portions of the adjacent permanent magnets are close to each other with a gap C interposed therebetween. This increases a magnetic flux density detected by a rotation detection sensor, thereby enabling the electricity consumption and the heat generation amount of a coil to be reduced.

Description

brushless motor

The present invention relates to a brushless motor.

As a conventional brushless motor, one described in Patent Document 1 below is known. This brushless motor is a so-called IPM motor, and has a rotor rotatably disposed inside a stator formed in a frame shape. A magnetic sensor is provided at one end of the stator to detect the magnetic pole position of the rotor.

The rotor has a rotatable shaft and a cylindrical rotor core that is integrally attached to the shaft. This rotor core has a plurality of through holes along the axial direction of the rotating shaft.

Further, the rotor has a plurality of permanent magnets inserted and fixed into each axial hole of the rotor core. Each of the permanent magnets is formed into a plate shape having a predetermined thickness, and has a protruding portion that partially protrudes from an opening at one end of each of the axial holes.

Furthermore, a magnetic sensor is provided at a position facing the outer peripheral portion of the rotor. This magnetic sensor detects the magnetic pole position of the rotor by detecting magnetic flux generated from each protrusion of a plurality of permanent magnets inserted and fixed into each through hole of the rotor core.

Japanese Patent Application Publication No. 2013-20783 (see Figures 1 and 3)

In the conventional brushless motor, the magnetic sensor detects the magnetic flux generated from each protrusion of the plurality of permanent magnets, but the distance between the adjacent protrusions is large. Therefore, there is a risk that the recognition of the switching of the magnetic pole by the magnetic sensor may be delayed.

That is, as the distance between adjacent protrusions increases, the timing at which the magnetic poles change becomes slower. Furthermore, since there is no permanent magnet that generates magnetic flux in the space between the protrusions of adjacent permanent magnets, the magnetic flux at the magnetic sensor position becomes weak, and the timing of the magnetic pole switching determination at the magnetic sensor is delayed. If there is a delay in recognizing the switching of the magnetic poles, the ideal energization timing will be delayed, and the current required to generate the same torque will increase. As a result, there is a possibility that the electricity cost and the amount of heat generated by the coil will increase.

The present invention was devised in view of the above-mentioned conventional technical problems, and reduces the distance between the extension parts (protrusions) of adjacent permanent magnets to reduce the weakening of the magnetic flux at the magnetic sensor position. One of the objects of the present invention is to provide a brushless motor that can reduce electricity costs and the amount of heat generated by the coil.

In one preferred embodiment, a plurality of plate-shaped permanent magnets are arranged inside each of the axial holes of the rotor core, and a main body located inside the plurality of axial holes; a permanent magnet having a protrusion protruding in the axial direction from an opening at one end of the axial hole;
a rotation detection sensor that is arranged to face the protrusion in the axial direction and detects a magnetic flux component in the rotation axis direction of the permanent magnet;
an extending portion provided on at least one side surface of each of the protrusions in the circumferential direction of the rotor and extending in the circumferential direction of the rotor so that adjacent protrusions approach each other through a gap; It is characterized by

According to a preferred embodiment of the present invention, it is possible to increase the detection magnetic flux density of the rotation detection sensor and reduce the electricity cost and the amount of heat generated by the coil.

1 is a longitudinal sectional view showing an embodiment of a brushless motor according to the present invention. 2 is an enlarged view of part A in FIG. 1. FIG. FIG. 2 is a schematic diagram showing the mounting positions of three magnetic sensors provided on a circuit board used in this embodiment. It is a distribution diagram of the magnetic flux density of the permanent magnet provided for this embodiment. FIG. 2 is an overhead view of a rotor used in this embodiment. (a) is an overhead view showing one of the permanent magnets taken out from the rotor, and (b) is a front view of the same permanent magnet. FIG. 2 is a perspective view of a rotor used in this embodiment, viewed from below. FIG. 2 is a side view of a rotor used in this embodiment. 9 is a sectional view taken along line BB in FIG. 8. FIG. 6 is an enlarged view of section C in FIG. 5. FIG. FIG. 6 is a characteristic diagram showing the relationship between magnetic flux density and rotor angle depending on the difference in the distance between the poles between the extension portions of adjacent permanent magnets used in this embodiment. FIG. 7 is an overhead view of a rotor used in a second embodiment of the present invention. FIG. 12 is an enlarged view of part D in FIG. 11. (a) is a perspective view showing another example of the permanent magnet used in the embodiment of the present invention, and (b) is a front view of the same permanent magnet. (a) is a perspective view showing still another example of the permanent magnet used in the embodiment of the present invention, and (b) is a front view of the same permanent magnet. (a) is a perspective view showing still another example of the permanent magnet used in the embodiment of the present invention, and (b) is a front view of the same permanent magnet.

Hereinafter, embodiments of the brushless motor according to the present invention will be described in detail based on the drawings.

FIG. 1 is a longitudinal sectional view of the brushless motor of this embodiment, FIG. 2 is an enlarged view of part A in FIG. 1, and FIG. 3 shows the mounting positions of three magnetic sensors provided on the circuit board used in this embodiment. It is a schematic diagram. Note that in FIG. 1, radial arrows indicate the radial direction of the rotor 5, and axial arrows indicate the rotational axis direction of the rotor 5.

The brushless motor 1 is an IPM motor, and as shown in FIGS. 1 and 2, the brushless motor 1 includes a bottomed cylindrical motor housing 2 fixed to a chain case, and a stator fixed to the inner peripheral surface of the motor housing 2. (Stator) 3, a motor output shaft 4 disposed on the inner circumference of the stator 3, a rotor 5 fixed to the outer circumference of the motor output shaft 4, and one end of the motor housing 2 in the axial direction (Fig. It has a control mechanism 6 provided on the middle left side).

The motor housing 2 is formed by bending, for example, an iron-based metal plate into a cup shape, and has a stator housing space S for housing the stator 3 and the like therein. The motor housing 2 has a through hole 2b formed approximately in the center of the bottom wall 2a, into which the motor output shaft 4 is inserted. This through hole 2b is formed inside a cylindrical portion 2c that is bent into a cylindrical shape at the center of the bottom wall 2a. Further, a cylindrical bearing holding portion 2g that holds a first ball bearing 15a, which will be described later, is provided near the cylindrical portion 2c of the bottom wall 2a.

Further, the motor housing 2 is integrally provided with a flange portion 2d projecting outward in the radial direction on the outer periphery of the open end of the rear end portion. This flange portion 2d has three bracket pieces 2e integrally provided at approximately 120° positions in the circumferential direction. Further, bolt insertion holes 2f into which three bolts 7 are inserted are formed through each of the three bracket pieces 2e. Note that there may be three or more bracket pieces 2e.

Each bolt 7 is adapted to fasten and fix the motor housing 2 and a casing 17 of the control mechanism 6, which will be described later, together, and also to fix them to a chain case (not shown). That is, in each bolt 7, a male threaded portion 7b on the outer periphery of the tip of the shaft portion 7a is fastened to a female threaded portion on the chain case, thereby fixing the motor housing 2 and the casing 17 to the chain case. Note that it is also possible to increase the number of bolt insertion holes 2f, bolts 7, etc. to three or more.

As shown in FIGS. 1 to 3, the stator 3 includes a stator core (iron core) 3a and a multi-phase (3-phase U, V, W) coil 3b wound around the outer periphery of the stator core 3a. . The stator core 3a is formed by laminating a large number of steel plates, and has a ring-shaped yoke (not shown) and a plurality of teeth protruding inward from the yoke. The coil 3b is wound around a plurality of teeth via an insulator.

The motor output shaft 4 is made of, for example, an iron-based metal material, and one end 4a in the direction of the rotating shaft protrudes from the through hole 2b via an oil seal 8, which will be described later.

The one end 4a of the motor output shaft 4 has a width across flats (not shown) formed along a tangential direction on the outer surface, and a pair of widths cut out from a direction perpendicular to the width across flats. A fitting groove is formed. As shown in FIG. 1, a stopper member 16 that restricts movement of the intermediate member 14 in the right direction in the figure is fitted and fixed in both fitting grooves from the radial direction. Further, one end portion 4a is supported by the motor housing 2 by a first ball bearing 15a held within the bearing holding portion 2g. The first ball bearing 15a has a general structure, and includes an outer ring fixed to the inner peripheral surface of the bearing holding part 2g, an inner ring fixed to the outer peripheral surface of one end 4a of the motor output shaft 4, and both wheels. It has a plurality of balls provided with a cage in between.

On the other hand, the other end 4b of the motor output shaft 4 is rotatably supported by a second ball bearing 15b provided in the casing 17 of the control mechanism 6. The second ball bearing 15b, like the first ball bearing 15a, includes an outer ring press-fitted into the inner circumferential surface of a bearing holding groove 18a of a cylindrical portion 18, which will be described later, and an outer circumferential surface of the other end 4b of the motor output shaft 4. It has an inner ring into which is press-fitted, and a plurality of balls provided between the two rings via a cage.

The oil seal 8 has a general structure, and the outer circumferential surface is press-fitted into the inner circumferential surface of the through hole 2b, while the inner seal piece is attached to the outer circumferential surface of one end 4a of the motor output shaft 4 by a backup spring. They are slidably abutted. Thereby, the oil seal 8 restricts oil from flowing into the motor housing 2 from the outside.

As shown in FIG. 1, the motor output shaft 4 has one end 4a disposed close to the head of a cam bolt (not shown) with a small gap from the rotation axis direction. The entire one end portion 4a including the stopper member 16 can be inserted from the axial direction into a hexagonal groove formed on the front end surface of the head of the cam bolt.

The stopper member 16 is formed in a C-ring shape and can be elastically deformed in the diameter expanding direction and the diameter contracting direction by its own elastic force.

An intermediate member 14 is provided at one end 4a of the motor output shaft 4. This intermediate member 14 constitutes a part of an Oldham joint which is a joint connected to a reduction gear (not shown).

FIG. 4 is a schematic diagram showing the mounting positions of three magnetic sensors provided on the circuit board used in this embodiment, FIG. 5 is an overhead view of the rotor used in this embodiment, and FIG. 6(a) is a diagram showing the rotor (b) is a front view of the permanent magnet, FIG. 7 is a perspective view of the rotor used in this embodiment, viewed from below, and FIG. 8 is a perspective view of the rotor used in this embodiment. 9 is a sectional view taken along line BB in FIG. 8, and FIG. 10 is an enlarged view of section C in FIG. 5.

As shown in FIGS. 1, 2, and 5 to 8, the rotor 5 is arranged on the inner circumferential side of the stator 3, and includes an annular rotor core 9 fixed to the outer circumference of the motor output shaft 4, and an annular rotor core 9 fixed to the outer circumference of the motor output shaft 4. A plurality of (eight in this embodiment) holding holes 10, which are a plurality of axial holes provided in the outer peripheral portion 9a of the rotor core 9, and eight permanent magnets 11 inserted and held in each of the holding holes 10, respectively. We are prepared. The rotor core 9 and the permanent magnets 11 are provided coaxially with respect to the motor output shaft 4.

The rotor core 9 is integrally formed of a metal material and has a substantially cylindrical outer circumferential portion 9a and a cylindrical inner circumferential portion 9b fixed to the motor output shaft 4. An intermediate portion between the outer circumferential portion 9a and the inner circumferential portion 9b is formed into a honeycomb shape in order to reduce the weight.

The outer peripheral portion 9a has a shape in which eight arcuate blocks are connected in an annular manner along the circumferential direction, and the inner peripheral surface 9c is formed in an octagonal shape. In the outer peripheral portion 9a, gaps each having a substantially triangular cross section are formed on the outside between each block, and are filled with a covering portion 24 made of a synthetic resin material, which will be described later. An insertion hole 9d into which the motor output shaft 4 is inserted and fixed is formed through the inner peripheral portion 9b in the central axial direction.

As shown in FIGS. 5, 6(a), and 7 to 10, each holding hole 10 is formed to penetrate along the inner axial direction of each block portion of the outer peripheral portion 9a. Each holding hole 10 is formed in the shape of a linear elongated hole substantially along the circumferential direction when viewed from above, and is formed into a substantially rectangular shape when viewed from the outside in the radial direction. Further, each holding hole 10 is formed so as to have a uniform cross-sectional area from one end opening 10a on the control mechanism 6 side in the axial direction to the other end opening 10b on the opposite side. Further, each holding hole 10 has both

end portions

10d and 10e formed in an arc shape when viewed from a plane (see FIG. 6(a)).

As shown in FIGS. 5 to 10, each permanent magnet 11 is made of a common composite alloy material such as neodymium (rare earth sintered magnet) into a plate shape with a predetermined thickness, and its overall shape is It is approximately T-shaped when viewed from above.

That is, as shown in FIG. 6, the permanent magnet 11 includes a main body 11a inserted into the holding hole 10, and a permanent magnet 11 protruding in the direction of the rotation axis of the rotor 5 from an opening 10a at one end of the holding hole 10 of the main body 11a. It has a protruding part 11b and a pair of extending

parts

12, 12 that are integrally provided on both sides of the protruding part 11b in the circumferential direction of the rotor 5, that is, in the width direction perpendicular to the longitudinal direction of the main body 11a. There is.

As shown in FIG. 6(b), the main body 11a and the protrusion 11b are each formed into a plate shape with a substantially uniform width W perpendicular to the longitudinal direction. This width length W is formed shorter than the length in the width direction of the holding hole 10, and when the main body 11a is inserted and held in the holding hole 10, as shown in FIG. Clearances C1 and C2 are respectively formed between the opposing inner surfaces in the width direction of the opposing holding holes 10. Each of the clearances C1 and C2 has a substantially arc-shaped cross section at each end face in the circumferential direction by retaining the shape of the arc-shaped

end portions

10d and 10e of each holding hole 10.

Further, each other end of each permanent magnet 11 on the opposite side in the axial direction from each protrusion 11b is a retreated portion 11c that is retreated further into the holding hole 10 than the other end opening 10b of each holding hole 10. .

As shown in FIG. 2, the protruding portion 11b has a protruding amount, that is, a length L from one end opening 10a of the holding hole 10 to the tip surface, of approximately 2 mm in this embodiment. On the other hand, the amount of retraction of the retracted portion 11c, that is, the length L1 from the hole edge of the other end opening 10b of the holding hole 10 to the rear end surface of the retracted portion 11c is approximately 1 mm in this embodiment.

As shown in FIG. 4(b), each of the extending

portions

12, 12 has the same protruding amount H, H in the circumferential direction of the rotor 5, and has the same protruding amount H, H in the axial direction of the rotor 5. The width lengths W1 and W1 are also the same and are formed to be the same as the protrusion amount L of the protrusion portion 11b. Further, as shown in FIGS. 3, 4(a), and 8, the extending portion 12 has one end surface 12a in the circumferential direction and the opposite end surface of another extending portion 12 adjacent in the circumferential direction of the rotor 5. A gap C is formed between each of them and 12b. This gap C is set to such a size that the distance X between the poles does not affect the magnetic flux mutually generated in each of the extending

portions

12, 12 facing each other in the circumferential direction.

The relationship between the magnetic flux density and the rotation angle of the rotor when the interpolar distance

Further, each extending portion 12 is provided within a range inside the outer circumferential surface of the outer circumferential portion 9a of the rotor core 9 when the main body 11a is inserted into the holding hole 10. Further, as shown in FIG. 10, when the main body 11a is inserted into the holding hole 10 through the opening 10a at one end, the extending

portions

12, 12 have both inner and outer

lower end edges

12c, 12d on the main body 11a side. is adapted to abut against the edge of one end opening 10a of the holding hole 10, that is, the radial edge of the rotor 5 across the respective clearances C1 and C2. This restricts the maximum insertion position of the permanent magnet 11 into the holding hole 10 of the main body 11a.

Further, the outer circumferential portion 9a of the rotor core 9, on the side of each protruding portion 11b and the side of each retreated portion 11c, is entirely covered with a covering portion 24 made of a synthetic resin material, which is a non-magnetic material. This covering portion 24 is formed into an annular shape so as to cover the entire outer circumferential surface of each protruding portion 11b. Further, the covering portion 24 is filled into the holding hole 10 from the other end opening 10b of the holding hole 10 so as to close each of the retreating portions 11c, and is formed into an annular shape as a whole. In addition, a part of the covering portion 24 is also filled in the triangular gaps between the blocks B of the outer peripheral portion 9a, and also between both circumferential side surfaces of the permanent magnet 11 and the facing surface of the holding hole 10 in the width direction. It also fills the gaps between.

As shown in FIGS. 1 to 3, the covering portion 24 is filled in the rear end opening of the holding hole 10 so as to close the retracted portion 11c, and this filling portion is filled with the rear end surface of the retracted portion 11c and the outside. Holes 13 are provided to communicate with each other. Each hole 13 is a support that is placed in advance in a mold and supports the rear end surface of each retreating portion 11c from below when molding a synthetic resin material onto the outer peripheral portion 9a of the rotor core 9 by injection molding, for example. This was formed at the mark left after the pin was removed after being molded.

The control mechanism 6 has a box-shaped casing 17 made of, for example, a synthetic resin material (non-magnetic material). As shown in FIG. 1, the casing 17 includes a square partition wall 17a disposed on the motor housing 2 side, and a square frame-shaped peripheral wall 17b rising from the outer periphery of the partition wall 17a. There is. Further, a substrate storage space S1 is formed inside surrounded by the partition wall 17a and the peripheral wall 17b.

The partition wall 17a is integrally provided with a cylindrical portion 18 in the center, and four small-diameter cylindrical boss portions 17e are integrally provided at the four corners of the inner surface. Each of the cylindrical boss portions 17e has a female screw hole (not shown), into which four screws (not shown) for fixing the rectangular circuit board 19 are screwed, at the tip thereof.

As shown in FIGS. 1 and 2, the partition wall 17a is provided with a first recess 20a at a portion facing a magnetic sensor 22, which will be described later, in the axial direction, and a portion facing a protrusion 11b of the permanent magnet 11. A second recess 20b is provided in the second recess 20b. The first recess 20a and the second recess 20b partially overlap in the radial direction, that is, they partially overlap in the radial direction.

The first recess 20a is formed in the shape of an annular groove, and its radial width is larger than the radial length of the magnetic sensor 22, so that the magnetic sensor 22 can enter therein. On the other hand, the second recess 20b is similarly formed in the shape of an annular groove, and its width in the radial direction is formed to be sufficiently larger than the thickness and width of the protrusion 11b, so that the protrusion 11b can enter therein. It has become.

As shown in FIG. 1, the circuit board 19 is housed in the board housing space S1, and a conductive circuit (not shown) such as a bus bar that supplies power to the brushless motor 1 is disposed inside. Further, on one side of the circuit board 19, a hole terminal is provided which is coupled by soldering to a plurality of terminal pieces of a connector 21, which will be described later. In addition, the circuit board 19 has an insertion hole 19a formed in the center through which the cylindrical portion 18 can be inserted, and four small-diameter screw insertion holes into which screws (not shown) are inserted at the four corners. It is formed.

In addition to the circuit board 19, the board housing space S1 also includes three

magnetic sensors

22a, 22b, and 22c, which are rotation detection sensors that are electrically connected to the circuit board 19 and control the drive of the brushless motor 1, and aluminum

electrolytic sensors

22a, 22b, and 22c. Multiple electronic components (not shown) such as capacitors, normal coils, common coils, and multiple ceramic capacitors are housed.

Three magnetic sensors 22a to 22c are provided on the circuit board 19, as shown in FIG. There are three magnetic sensors: a V-phase magnetic sensor 22b provided between the U-phase and the U-phase, and a U-phase magnetic sensor 22c provided between the U-phase and the W-phase. Furthermore, each of the magnetic sensors 22a to 22c detects an axial magnetic flux component (magnetic flux density) rather than a radial magnetic flux component of the permanent magnet 11, and determines whether the magnetic flux density is positive or negative. It has become.

As shown in FIGS. 1 and 2, each of the magnetic sensors 22a to 22c is located on the circuit board 19 at a position away from the arrangement position of the permanent magnet 11 in the direction of the rotation axis of the rotor 5, and in the radial direction. It is located outside of the That is, as shown in FIGS. 3 and 4, each of the magnetic sensors 22a to 22c is arranged at a position deviated outward in the radial direction from the center position of each permanent magnet 11 in the circumferential direction. This is because, as will be described later, the unique arrangement of the permanent magnets 11 increases detection accuracy due to the characteristics of the magnetic sensors 22a to 22c in detecting magnetic flux components (magnetic flux density) in the axial direction.

Further, as shown in FIG. 3, each of the magnetic sensors 22a to 22c is arranged so as to straddle an annular gap C3 between the inner circumferential surface of the stator 3 and the outer circumferential surface of the rotor 5. P1 is located in the annular gap C3.

Further, each of the magnetic sensors 22a to 22c is partially disposed between each coil 3b at the mounting position in the circumferential direction of the stator 3, and is connected to the protruding portion 11b (extending portion 12) of the permanent magnet 11 in the axial direction. They are located at almost opposite positions.

The cylindrical portion 18 is formed into a substantially cylindrical shape with a bottom, and one end and the other end in the axial direction face the stator housing space S and the board housing space S1, respectively, with the partition wall 17a as the center. That is, one end is arranged in the stator accommodation space S, and the other end is arranged in the board accommodation space S1. Further, the cylindrical portion 18 has a bearing holding groove 18a that accommodates and holds the second ball bearing 15b therein.

The peripheral wall 17b is integrally provided with a connector 21 for both signal and power supply on the outer periphery. This connector 21 is formed into a box shape, and one end portion of a pair of terminal pieces (not shown) is arranged inside. The other end of this terminal piece (not shown) located in the board accommodation space S1 is coupled to a hole terminal of a conductive circuit of the circuit board 19 by soldering. One end of the pair of terminal pieces located inside the connector 21 is partially connected to an engine control unit (ECU) (not shown) via a female terminal to a battery as a power source. Further, the other part outputs information signals such as magnetic pole position signals detected by each of the magnetic sensors 22a to 22c to the ECU.

Further, a cover member 23 is attached to the outer periphery of the peripheral wall 17b on the opposite side from the motor housing 2. The cover member 23 is made of, for example, a synthetic resin material and is formed into a plate-like rectangular shape, and an outer peripheral portion 23a bent in a crank shape toward the casing 17 is fixed to the peripheral wall 17b of the casing 17 by a predetermined fixing means. It has become so.

The ECU controls the rotation of the motor output shaft 4 by energizing the coil 3b of the brushless motor 1 based on signals from the magnetic sensor 22 and the like.
[Function and effect of brushless motor]
The functions and effects of the brushless motor of this embodiment will be explained below.

That is, according to the present embodiment, each of the magnetic sensors 22a to 22c detects an axial magnetic flux component, which is cheaper than one that detects a radial magnetic flux component. Therefore, the cost of the magnetic sensors 22a to 22c itself can be reduced. The magnetic sensors 22a to 22c are Hall ICs, and the sensor cores of the Hall ICs are plate-shaped. The magnetic flux passing through the plate-shaped sensor core in the thickness direction is detected.

Moreover, each of the magnetic sensors 22a to 22c is arranged at a position away from the permanent magnet 11 in the rotational axis direction of the rotor 5 and at a position outside the rotor 5 in the radial direction. That is, each of the magnetic sensors 22a to 22c is provided at a position shifted outward in the radial direction of the rotor 5 with the permanent magnet 11 as the center. This makes it easier for the magnetic flux density of the permanent magnet 11 to reach its peak value, thereby improving detection performance and making it less susceptible to variations in the axial positions of the magnetic sensors 22a to 22c.

Furthermore, in this embodiment, each of the magnetic sensors 22a to 22c is attached to a measurement position on the outside in the radial direction, and is also attached so as to straddle between the permanent magnet 11 and the coil 3b. As a result, the peak value of the magnetic flux component in the axial direction of the permanent magnet 11 is high, and it becomes less susceptible to the magnetic flux component generated from the coil 3b. As a result, the detection accuracy of each of the magnetic sensors 22a to 22c is increased, and stable detection performance can be obtained.

Further, as a result of investigating the magnetic flux density distribution of the permanent magnet 11 by the present inventor, it was found that, due to its characteristics, the magnetic flux density T of the permanent magnet 11 is lower than the central axis P of the permanent magnet 11, as shown in the magnetic flux density distribution diagram of FIG. It can be seen that the Q area on the outside in the radial direction or the R area on the inside in the radial direction from the central axis P is sufficiently higher than the area.

Furthermore, by locating the magnetic sensor 22 on the outside of the permanent magnet 11 in the radial direction rather than on the inside, the angular error due to variations in the mounting of the magnetic sensor 22 is reduced, and detection accuracy can be increased. can. That is, if the three magnetic sensors 22a to 22c are mounted on the inside in the radial direction, an error in the mounting angle of the three magnetic sensors 22a to 22c is likely to occur, but if they are mounted on the outside in the radial direction, the error in the mounting angle is less likely to occur.

Therefore, in this embodiment, each of the magnetic sensors 22a to 22c is attached to a predetermined position on the outside in the radial direction, and the sensor center P1 is placed in the annular gap C3 between the rotor 5 and the stator 3, as shown in FIG. The magnet 11 was positioned so as to straddle between the permanent magnet 11 and the coil 3b. As a result, the peak value of the magnetic flux component in the axial direction of the permanent magnet 11 is high, and it becomes less susceptible to the magnetic flux component generated from the coil 3b. As a result, the detection accuracy of each of the magnetic sensors 22a to 22c is increased, and stable detection performance can be obtained.

Furthermore, each of the magnetic sensors 22a to 22c is installed at a position where it straddles the annular gap C3 between the rotor 5 and the stator 3 in the radial direction. Since this is the position where the peak value is high, the detection performance of each magnetic sensor 22a to 22c is high.

Furthermore, each of the magnetic sensors 22a to 22c is partially disposed between each coil 3b at the mounting position in the circumferential direction of the stator 3, so that the influence of the magnetic flux of the coil 3b can be sufficiently avoided. Control accuracy increases.

In the present embodiment, two

extension parts

12, 12 are provided on both sides of the protrusion part 11b of each permanent magnet 11, and one end face 12a of one of the extension parts 12 adjacent in the circumferential direction and the rotor 5 Since the distance X between the poles and the other end surface 12b of the other extending portion 12 facing each other in the circumferential direction is made smaller than that of the prior art, the following effects can be obtained.

FIG. 11 is a characteristic diagram showing the relationship between the magnetic flux density T and the rotor angle deg due to the difference in the interpolar distance . This represents the results of experiments conducted by the inventor of the present application with various changes in the inter-electrode distance X. This is a comparison between the two electrodes having different interpolar distances X1, X2, and X3.

In this experiment, the distance between poles X' of the conventional technology was set to 4.66 mm, and as the present embodiment, the distance between poles X1 was set to 3.74 mm in the first example, and the distance between poles X2 was set to 3.74 mm in the second example. In the third example, the interpolar distance X3 was set to 1.15 mm.

From the characteristic diagram in FIG. 11, the magnetic sensors 22a to 22c recognize that the magnetic poles have changed when the magnetic flux density T exceeds the sensor threshold. It is clear that as the interpolar distance X becomes smaller, the slope of the magnetic flux density T near the sensor threshold changes.

That is, in the case of the distance X' between the poles of the conventional technology in which the protruding part 11b of the permanent magnet 11 does not have the extending

parts

12, 12, the magnetic flux density T with respect to the rotation angle of the rotor 5 is The slope becomes smaller, and the rotor rotation angle is approximately 13 degrees at the sensor threshold.

On the other hand, in the first to third examples of this embodiment, the slope of the magnetic flux density T gradually increases, and in the first example (distance between poles X1), as shown by the thin solid line in the figure, The slope is slightly higher than the technology (broken line), and the rotor rotation angle is about 11.5 degrees at the sensor threshold. Therefore, it is clear that the conventional technique is 13deg−11.5deg=1.5deg, which is 1.5deg faster than the conventional technique. This makes it possible to recognize the timing at which the north and south magnetic poles change earlier than in the prior art.

In the second example (distance between poles It is clear that the speed is further increased by 3 degrees.

In the third example (distance between poles X3), as shown by the thick solid line in the figure, the slope is even larger than that of the conventional technique, and the rotor rotation angle is approximately 7.5 degrees at the sensor threshold, which is 5.5 degrees greater than that of the conventional technique. It is clear that the speed is increased by 5 degrees. Therefore, in the second and third examples as well, it becomes possible to recognize the timing at which the magnetic poles of the north and south poles change more quickly than in the prior art.

As described above, in this embodiment, since the timing at which the magnetic poles of N and S poles change can be recognized quickly, the magnetic flux at the positions of each magnetic sensor 22a to 22c is increased, and the detection delay of each magnetic sensor 22a to 22c is reduced. can be reduced.

That is, as in the prior art, if the detection speed of the magnetic sensor is delayed, the timing of energization is delayed, and as a result, the current that generates the same torque increases.

In contrast, in the present embodiment, since the detection delay of the magnetic sensors 22a to 22c can be reduced, the power consumption rate (electricity cost) and the amount of heat generated by the coil wound around the stator core can be reduced. Furthermore, costs associated with changing element parts compatible with high current can be reduced.

In addition, in this embodiment, since the gap C of the predetermined inter-pole distances X1 to X3 described above is provided between both

adjacent extensions

12, 12, if there is no gap It is possible to suppress the occurrence of cracks, damage, etc. due to vibration, etc., which may occur when the protruding

parts

12, 12 are in contact with each other.

In this embodiment, the main body 11a of the permanent magnet 11 has a retracted portion 11c located inside the other end opening 10b of the axial hole. In other words, the other end of the main body 11a of the permanent magnet 11 can be cut short by the magnetic force of the

extensions

12, 12, so the overall weight and volume of the permanent magnet 11 can be reduced.

Further, as described above, when the main body 11a of each permanent magnet 11 is inserted into the holding hole 10, both lower end edges 12c and 12d of the

extension parts

12, 12 are inserted into the opening 10a at one end of the holding hole 10. It comes into contact with the edge and further insertion is restricted. Thereby, the maximum insertion position of the permanent magnet 11 into the holding hole 10 is determined. As a result, the work of inserting each permanent magnet 11 into the holding hole 10 becomes easier.

Since each of the extending

portions

12, 12 is provided within a range inside the outer circumferential surface of the outer circumferential portion 9a of the rotor core 9, the extending

portions

12, 12 are provided within a range inside the outer circumferential surface of the outer circumferential portion 9a of the rotor core 9. Contact with the coil 3b is avoided, and damage to the extension portion, stator core 3a, etc. due to interference due to vibration or the like can be suppressed.

Further, in the permanent magnet 11, the protruding portion 11b and the recessed portion 11c are covered with a covering portion 24 made of a synthetic resin material at the front and rear in the axial direction, and the holding hole 10 is also filled with the covering portion 24 to cover the holding hole 10. As a result, displacement of the permanent magnet 11 is suppressed, so that the magnetic field can be stabilized, and cracking and scattering of the permanent magnet 11 due to impact can be suppressed.
[Second embodiment]
12 and 13 show a second embodiment of the present invention, and the basic configuration is the same as that of the first embodiment, but the lengths H and H of each extending

portion

12 and 12 in the circumferential direction of the rotor 5 are was formed for a long time.

That is, as shown in FIG. 12, the lengths H, H of the extending

portions

12, 12 provided on both side surfaces of the protruding portion 11b of the permanent magnet 11 are set by the extending portions 12 of the other adjacent

permanent magnets

11, 12 and is made longer within a range that does not interfere with 12.

As a result, as shown in FIG. 13, each of the extending

portions

12, 12 has both

lower end edges

12c, 12d with a clearance of one end opening 10a of the holding hole 10 when the main body 11a is inserted into the holding hole 10. It contacts the hole edge in a manner that covers the entirety of C1 and C2.

Therefore, according to the present embodiment, since the one end opening 10a of the holding hole 10 is entirely covered by each of the extending

portions

12, 12, dust and contaminants are prevented from entering into the holding hole 10 from the one end opening 10a. Can be suppressed.

Since the rest is the same as the first embodiment, the same effects as the first embodiment described above can be obtained.
[Other examples of permanent magnets]
14 to 16 show a plurality of examples in which the shapes of the protruding portion 11b and the extending

portions

12, 12 of the permanent magnet 11 are changed.

First, in the example shown in FIGS. 14(a) and 14(b), a notch groove 25 is formed in the center of the upper end of the protrusion 11b. This cutout groove 25 is formed by cutting out a part of the upper end of the protrusion 11b in a rectangular shape along the direction of the extensions 12 .

This reduces the weight and volume of the permanent magnet 11, making it possible to make the entire permanent magnet 11 lighter and more compact.

In the example shown in FIGS. 15(a) and 15(b), an arcuate groove 26 is formed by continuously cutting out the upper end portions of both the

extension portions

12, 12 and the protruding portion 11b in an arcuate concave shape.

Also in this case, since the weight and volume of the permanent magnet 11 are reduced, the permanent magnet 11 as a whole can be made lighter and more compact.

In the example shown in FIGS. 16(a) and 16(b), an arcuate protrusion 27 is formed by continuously cutting out the upper ends of both the

extensions

12, 12 and the protrusion 11b in an arcuate shape. This example also provides the same effects as the above two examples.

The present invention is not limited to the configuration of the embodiment described above, and only one

extension portion

12, 12 of the permanent magnet 11 is provided on one side of the protrusion portion 11b, and the protrusion portions of the adjacent permanent magnets 11 are It is also possible to form a gap C between it and 11b.

In addition, the protrusion amount L (W1) of the protrusion portion 11b of each permanent magnet 11 and each

extension portion

12, 12, and the retraction amount L1 of the retraction portion 11c are determined depending on the specifications of the brushless motor 1, the magnitude of the magnetic force, etc. It is possible to determine the length relatively.

Applicable devices for the brushless motor 1 include not only valve timing control devices for internal combustion engines, but also various in-vehicle motors such as power steering motors, power window motors, sunroof motors, and power seat motors, as well as home appliances such as air conditioners. It can also be applied to motors used in other applications.

DESCRIPTION OF SYMBOLS 1... Brushless motor, 2... Motor housing, 3... Stator, 3a... Stator core, 3b... Coil (winding), 4... Motor output shaft, 5... Rotor, 6... Control mechanism, 9... Rotor core, 9a... Outer periphery, 9b...Inner peripheral part, 10...Holding hole, 10a...One end opening, 10b...Other end opening, 11...Permanent magnet, 11a...Main body, 11b...Protrusion part, 11b...Retreating part, 12...Extending part, 17 ...Casing, 18...Cylindrical part, 19...Circuit board, 22 (22a to 22c)...Magnetic sensor (rotation detection sensor), 23...Cover member, 24...Synthetic resin covering part, 25, 26, 27...Permanent Other examples of magnets, C...gap, C1/C2...clearance, X(X1-X3)...distance between poles, X'...distance between poles of conventional technology.

Claims

A stator including a stator core and a plurality of windings wound around the stator core;
A rotor having a rotor core arranged inside or outside the stator and having a plurality of axial holes formed at predetermined intervals in the circumferential direction;
A plurality of plate-shaped permanent magnets are arranged inside each of the axial holes of the rotor core, the main body being located inside the plurality of axial holes, and one end opening of the plurality of axial holes. the permanent magnet having a protrusion protruding in the axial direction;
a rotation detection sensor that is arranged to face the protrusion in the axial direction and detects a magnetic flux component of the permanent magnet;
an extending portion provided on at least one side surface of each of the protrusions in the circumferential direction of the rotor and extending in the circumferential direction of the rotor so that adjacent protrusions approach each other through a gap;
A brushless motor characterized by:
The brushless motor according to claim 1,
The brushless motor is characterized in that the extending portion is provided on both side surfaces of the protruding portion in the circumferential direction of the rotor.
The brushless motor according to claim 2,
A brushless motor characterized in that a gap is formed between the circumferentially adjacent extending portions.
The brushless motor according to claim 1,
The brushless motor is characterized in that the end surface of the permanent magnet main body on the opposite side in the axial direction with respect to the protrusion is disposed inside the other end opening of the axial hole.
The brushless motor according to claim 1,
The brushless motor is characterized in that an edge of the extending portion on the main body side abuts a part of a hole edge of an opening at one end of the axial hole of the rotor core from the axial direction.
The brushless motor according to claim 1,
The axial hole is formed in a long hole shape that is longer in the circumferential direction of the rotor than the main body of the permanent magnet,
An end edge of the extending portion on the main body side is in axial contact with at least one of a radially outer hole edge and a radially inner hole edge of the hole edge of the opening at one end of the axial hole. A brushless motor characterized by:
The brushless motor according to claim 6,
When the main body of the permanent magnet is inserted into the axial hole, a clearance is formed between both sides in the width direction and both sides of the main body,
The extending portion has an end edge on the main body side that is in axial contact with both a radially outer and a radially inner hole edge of the one end opening, and the end edge of the extending portion on the one end opening side is in contact with both the radially outer and radially inner hole edges of the one end opening. A brushless motor characterized by covering the clearance.
The brushless motor according to claim 6,
The brushless motor is characterized in that the extending portion is located within a range inside an outer circumferential surface of an outer circumferential portion of the rotor core in which the axial hole is formed.