JP2019146427A - Brushless motor - Google Patents

Abstract

To improve quality and manufacturing efficiency of a brushless motor comprising a ring magnet.SOLUTION: The brushless motor comprises a rotor 16 pivotally supported inside a stator 15 rotatably, where the rotor 16 has a shaft 18 in a circular column shape and a ring magnet 28 fixed to a magnet attachment part 26 provided in the shaft 18 through an adhesive agent 27. In the ring magnet 28, a plurality of magnetic poles are magnetized with different magnetism being adjacent to each other in a circumferential direction. In the magnet attachment part 26, a plurality of adhesive agent grooves 47 storing the adhesive agent 27 are extended along a shaft direction. The adhesive agent grooves 47 are provided to correspond to center parts in the circumferential direction of the magnetic poles.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a brushless motor having a ring magnet bonded to a magnet mounting portion of a shaft.

  The brushless motor has a rotor provided with a magnetic field magnet and a stator provided with an armature winding. The position of the rotor is detected by a Hall element that is a magnetically sensitive element, and the energization timing for each stator coil is controlled by an inverter based on the detection signal of the Hall element. The rotor includes a surface magnet type (SPM) in which a plurality of magnets are attached to the outer periphery of the rotor and an embedded magnet type (IPM) in which a plurality of permanent magnets are embedded in the rotor. Furthermore, there are types of rotors with ring magnets. This type of rotor is a ring magnet in which N poles and S poles as magnetic poles are alternately shifted in the circumferential direction on a cylindrical member made of a magnetic material. It has.

  Patent Documents 1 and 2 each disclose a rotor or a rotor including a ring magnet. The rotors disclosed in these Patent Documents 1 and 2 have a yoke, that is, a rotor core, which is formed of a laminate of metal plates and forms a part of a shaft, and a magnet ring is attached to the outer peripheral surface of the rotor core. There is a type of rotor in which the outer peripheral surface of the shaft is a magnet mounting portion and a ring magnet is mounted on the outer peripheral surface of the shaft.

  On the other hand, Patent Document 3 discloses a brake device for parking a vehicle having a brushless motor, and this brake device has a caliper arranged so as to straddle a part of a brake disk attached to an axle. Yes. The caliper includes a cylinder portion provided with a piston, and a claw portion facing the cylinder portion via a disk, and a pad pressed against the brake disk is provided on the piston and the claw portion. When the brake pedal is operated, hydraulic pressure is supplied to the piston, and each pad is pressed against the brake disc to apply a braking force to the axle. A feed screw member that is rotationally driven by a brushless motor via a speed reducer is screwed to the piston. When the parking brake switch is operated, the piston is driven by the feed screw member to apply a braking force to the axle. Patent Document 3 is a parking brake device. However, when a reciprocating member provided with a pad is driven by a motor instead of a piston, the brake device is an electric brake that is also used for braking during vehicle travel.

JP-A-8-182294 JP 2003-174745 A Japanese Patent Laid-Open No. 2006-125512

  A rotor provided with a ring magnet is formed by magnetizing magnetic poles on a cylindrical member integrally formed of a magnetic material, so that the magnetic poles can be allocated evenly in the circumferential direction. Furthermore, a rotor can be manufactured with few assembly steps. Thereby, the rotor provided with the ring magnet has an advantage that a high-precision brushless motor can be manufactured at low cost.

  However, since the ring magnet is fixed to the outside of the shaft with an adhesive, the adhesive may leak from between the shaft and the ring magnet when the rotor is manufactured. If the adhesive leaks to the outside of the rotor, the adhesive may adhere to the outer surface of the rotor or the adhesive may adhere to a jig for assembling the rotor. For this reason, work processes such as inspection and cleaning of the rotor and cleaning of the jig increase, and the manufacturing efficiency of the motor decreases. Moreover, after the adhesive adhering to the outer surface of the rotor is solidified, it peels off to form an adhesive piece, which is scattered in the brushless motor, which may cause the adhesive piece to bite into the motor and cause malfunction. This is a problem particularly in a motor that requires high reliability such as the motor for a brake device described above.

  The objective of this invention is improving the quality and manufacturing efficiency of a brushless motor provided with the ring magnet.

  The brushless motor of the present invention is a brushless motor comprising a stator and a rotor rotatably supported inside the stator, the rotor being provided on a cylindrical shaft and the shaft. A ring magnet fixed to the magnet mounting portion via an adhesive, and a plurality of magnetic poles are magnetized adjacent to the ring magnet with different polarities in the circumferential direction. A plurality of adhesive grooves are provided along the axial direction, and the adhesive grooves are provided corresponding to the central portion of the magnetic pole in the circumferential direction.

  The rotor of the brushless motor has a ring magnet fixed to the magnet mounting portion of the shaft by an adhesive, and a plurality of magnetic poles are magnetized adjacent to each other with different polarities in the circumferential direction. In the magnet mounting part, an adhesive groove that accommodates the adhesive is extended along the axial direction, and the adhesive groove is provided corresponding to the center part in the circumferential direction of the magnetic pole, so the magnet mounting When the ring magnet is fitted to the part, the adhesive is prevented from entering the adhesive groove and leaking out of the rotor. As a result, the adhesive is prevented from adhering to the jig for assembling the rotor, and the work such as cleaning of the jig becomes unnecessary, and the manufacturing efficiency of the motor can be improved. Since the ring magnet is bonded to the shaft by the adhesive that has entered the gap between the ring magnet and the magnet mounting part and the adhesive that has entered the adhesive groove, the adhesive strength of the rotor is increased, and the brushless motor Can improve the quality.

It is a longitudinal section showing a brushless motor which is one embodiment. FIG. 2 is an enlarged cross-sectional view of FIG. 1. It is a block diagram which shows the rotation control circuit of a motor. It is an expansion perspective view which shows the rotor shown by FIG. FIG. 5 is an exploded perspective view of FIG. 4. It is an expansion cross-sectional view of a rotor. (A) is a longitudinal cross-sectional view which shows a part of rotor, (B) (C) is a longitudinal cross-sectional view which shows a part of rotor which is a modification, respectively. It is sectional drawing which shows the state which has processed the adhesive groove with the rolling roller. (A) (B) is a cross-sectional view of the rotor which is a modification, respectively. It is a top view which shows the external appearance of the rotor which is a modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the brushless motor 10 includes a motor case 11. The motor case 11 is formed by pressing a metal plate such as deep drawing, and has a bottom wall portion 11a and a cylindrical portion 11b. A flange portion 11c is provided at an opening end portion 12 of the cylindrical portion 11b. Yes. A bracket 13 made of a resin material is attached to the flange portion 11c.

  A plurality of collars 14 are attached to the bracket 13, and the brushless motor 10 is attached to a member (not shown) by a screw member penetrating each collar 14. The brushless motor 10 can be applied to drive a brake device of an automobile. In this case, the motor case 11 is attached to the speed reducer by a screw member that penetrates the collar 14.

  As shown in FIG. 1, a stator 15 is fixed to a cylindrical portion 11 b of the motor case 11, and a rotor 16 is rotatably supported inside the stator 15 via an air gap, that is, a gap 17. The rotor 16 has a cylindrical shaft 18, and a lower end portion of the shaft 18 in FIG. 1 is rotatably supported on the motor case 11 by a bearing 21, and an upper end portion is rotatably supported on the bracket 13 by a bearing 22. The The bearing 21 is attached to a cylindrical portion 23 provided on the bottom wall portion 11 a of the motor case 11, and the bearing 22 is attached to a holder 24 attached to the bracket 13.

  If the lower end portion of the shaft 18 in FIG. 1 is the base end portion of the shaft 18 and the upper end portion is the distal end portion, a pinion gear 25 is attached to the distal end portion. When the brushless motor 10 is applied for driving a brake device of an automobile, the rotation of the pinion gear 25 is transmitted to a feed screw shaft through a reduction gear mechanism (not shown). The feed screw shaft is screwed to a reciprocating member which is mounted on a caliper of the brake device so as to be reciprocally movable in the axial direction. The reciprocating member and the claw portion of the caliper opposed to the reciprocating member are provided with pads that are pressed against the brake disc of the electric brake device of the automobile, respectively, and a braking force is applied to the automobile by the brushless motor 10.

  As shown in FIG. 1 and FIG. 2, the shaft 18 is provided with a magnet mounting portion 26 composed of an outer peripheral surface having a larger diameter than both ends, and an adhesive 27 is attached to the outer periphery of the magnet mounting portion 26. The ring magnet 28 is fixed. The ring magnet 28 is formed by alternately magnetizing an N pole and S pole as magnetic poles in a circumferential direction on a cylindrical member made of a magnetic material. Accordingly, the magnetic poles are magnetized on the ring magnet 28 with different polarities adjacent to each other in the circumferential direction. The ring magnet 28 shown in FIG. 2 has 10 magnetic poles magnetized in the circumferential direction, and the rotor 16 has 10 poles. In FIG. 2, the boundary portion of the magnetic pole of the ring magnet 28 is indicated by a broken line. As described above, the brushless motor 10 is a ring magnet type, and unlike the surface magnet type or embedded magnet type rotor, as described above, the magnetic poles can be evenly allocated in the circumferential direction and the number thereof is small. The rotor 16 can be manufactured with assembly steps. In the surface magnet type rotor, it is conceivable that the arc-shaped magnet attached to the outer peripheral surface of the cylindrical member is detached, but the durability of the motor can be improved by the ring magnet 28.

  The stator 15 has a substantially cylindrical stator core 31. As shown in FIG. 2, the stator core 31 is formed by combining nine teeth portions 32 in the circumferential direction. Each tooth part 32 is formed by laminating a plurality of metal plates (electromagnetic steel plates) punched by press working. Each metal plate is provided with a through hole (not shown) for positioning during lamination. An insulator 33 made of an insulating resin material is attached to each tooth portion 32, and a coil 34 is wound around the outside of the insulator 33. Coils 34 are wound around the nine teeth portions 32, and the stator 15 shown in FIGS. 1 and 2 has nine coils 34.

  Each coil 34 constitutes three phases of a U phase, a V phase, and a W phase in order in the circumferential direction, and each phase is formed by three coils 34. As shown in FIG. 1, a bus bar unit 35 is disposed on the end surface of the stator 15 on the front end side. The bus bar unit 35 electrically connects the terminals of the coils 34 and an external power source. A sensor disk 36 is attached to the shaft 18 in order to detect the position of the rotor 16 in the rotational direction. The sensor disk 36 is provided with a magnet. A sensor substrate 37 is attached to the bracket 13 so as to face the sensor disk 36, and a Hall element that is sensitive to the magnetic force of the magnet provided on the sensor disk 36 is provided on the sensor substrate 37.

  FIG. 3 is a block diagram showing a motor rotation control circuit. The rotation control circuit has three Hall elements 38a to 38c corresponding to the three-phase coils, and each Hall element is attached to the sensor substrate 37 shown in FIG. 1 as described above. Each Hall element 38a to 38c detects the magnetic flux provided by the magnet provided on the sensor disk 36, and outputs a detection signal when the polarity of the magnetic pole part of the rotor 16 changes from the N pole to the neutral point. This is a magnetic field detection element to be output. The position of the rotor 16 is detected based on the detection signal from the Hall element, and the energization switching operation for each coil 34 is performed. The sensor for detecting the rotation position is not limited to the Hall element, but an electronic element having a comparator function and a Hall IC in which the Hall element is integrated into one chip may be used.

  The motor rotation control circuit has an inverter circuit 41 for controlling the drive current for the U-phase, V-phase, and W-phase coils 34. The inverter circuit 41 is a three-phase full-bridge inverter circuit, and includes two switching elements T1 and T2, two switching elements T3 and T4, and two switching elements T5 and T6 connected in series, Each is connected to the positive and negative output terminals of the DC power supply 42. One connection terminal of the U-phase coil 34 is connected between the two switching elements T1 and T2. One connection terminal of the V-phase coil 34 is connected between the two switching elements T3 and T4. One connection terminal of the W-phase coil 34 is connected between the two switching elements T5 and T6. The other connection terminals of the U-phase, V-phase, and W-phase coils 34 are connected to each other, and each coil 34 is star-connected. In addition, as a connection system, it is good also as a delta connection. The commutation operation for each coil 34 is controlled by adjusting the timing of the control signal supplied to each switching element.

  The motor rotation control circuit has a controller 43, and a control signal is sent from the controller 43 to the inverter circuit 41 via the control signal output circuit 44. Detection signals of the hall elements 38 a to 38 c as the rotational position detection sensors are sent to the rotor position detection circuit 45. A signal is sent from the rotor position detection circuit 45 to the controller 43. The controller 43 includes a microprocessor that calculates a control signal and a memory that stores a control program, data, and the like.

  The inverter circuit 41, the controller 43, the rotor position detection circuit 45, etc. are provided outside the motor, and the lead wires for connecting one connection terminal of each phase coil and the inverter circuit 41 are shown in FIG. Thus, it is guided to the outside through the cable guide 46 provided in the bracket 13. Lead wires connecting the three Hall elements 38a to 38c and the rotor position detection circuit 45 are also guided to the outside.

  4 is an enlarged perspective view showing the rotor shown in FIG. 1, and FIG. 5 is an exploded perspective view of FIG. FIG. 6 is an enlarged cross-sectional view of the rotor.

  As shown in FIGS. 4 and 5, one ring magnet 28 is mounted on the magnet mounting portion 26 of the shaft 18, but two ring magnets having a half length of the ring magnet 28 are provided. One magnet may be mounted on the magnet mounting portion 26. As shown in FIG. 5, an adhesive groove 47 extends along the axial direction of the shaft 18 in the magnet mounting portion 26. As shown in FIG. 6, ten adhesive grooves 47 are provided at intervals in the circumferential direction corresponding to the central portions in the circumferential direction of the N and S poles, which are magnetic poles. As described above, the central portion of the magnetic pole in the circumferential direction is a region where the magnetic flux hardly flows as conceptually shown by an arrow in FIG. 6, and the adhesive groove 47 is provided in the region. Even if the agent groove 47 is provided, a decrease in the output torque of the motor is suppressed.

  As described above, the ring magnet 28 is manufactured by magnetizing a magnetic pole on a cylindrical member made of a magnetic material. However, the ring magnet 28 may be fixed to the magnet mounting portion 26 after being magnetized. Alternatively, the cylindrical member may be magnetized after being fixed to the magnet mounting portion 26. When the magnetized ring magnet 28 is mounted on the magnet mounting portion 26, the adhesive groove 47 can be used as a positioning groove for mounting the ring magnet 28. On the other hand, when magnetizing after mounting on the magnet mounting portion 26, the adhesive groove 47 can be used as a positioning groove for magnetization.

  In the rotor 16 shown in FIG. 6, the number of the adhesive grooves 47 in the circumferential direction is set to be the same as the number of magnetic poles. As shown in FIG. 5, each adhesive groove 47 is divided into five groove portions 47a with an interval in the axial direction. That is, each adhesive groove 47 is formed by the plurality of groove portions 47a that are divided and arranged in a row along the axial direction.

  An adhesive 27 for fixing the ring magnet 28 to the magnet mounting portion 26 is applied to the outer peripheral surface of the magnet mounting portion 26, and the ring magnet 28 is mounted on the magnet mounting portion 26 to which the adhesive 27 has been applied. When the ring magnet 28 is mounted, the adhesive 27 is supplied between the outer peripheral surface of the magnet mounting portion 26 and the inner peripheral surface of the ring magnet 28 and enters the respective adhesive grooves 47. When the ring magnet 28 is mounted on the magnet mounting portion 26, the adhesive 27 can be filled in the adhesive groove 47 by moving the ring magnet 28 in the axial direction with respect to the shaft 18 and rotating the ring magnet 28.

  When the ring magnet 28 is mounted on the magnet mounting portion 26 of the shaft 18 by inserting the adhesive 27 into the adhesive groove 47, an amount of the adhesive 27 corresponding to the gap 17 and the volume of the adhesive groove 47 is mounted on the magnet. Applying a larger amount of adhesive 27 than in the case of applying only an amount of the adhesive 27 commensurate with the welding of the gap 17 will ensure that there is no gap in the entire gap 17. The adhesive 27 can be dispersed in the adhesive. When the ring magnet 28 is attached, the adhesive 27 is prevented from entering the adhesive groove 47 and leaking out of the rotor. As a result, the adhesive is prevented from adhering to the jig for assembling the rotor, and the work such as cleaning of the jig becomes unnecessary, and the manufacturing efficiency of the motor can be improved. Furthermore, since the adhesive 27 is also contained in the adhesive groove 47, the adhesive strength can be increased.

  After the adhesive 27 is filled between the ring magnet 28 and the shaft 18, the ring magnet 28 is fixed to the shaft 18 by drying and curing the adhesive 27. Before the adhesive 27 is cured, the center of the outer periphery of the ring magnet 28 is aligned with the center line of the shaft 18 so that the ring magnet 28 can be centered. Thus, the roundness of the ring magnet can be increased under the condition that the adhesive 27 is dried and cured and the ring magnet 28 is fixed.

  FIG. 7A is a longitudinal sectional view showing a part of the rotor 16 shown in FIG. The adhesive groove 47 has a plurality of groove portions 47a formed in rows along the axial direction at intervals, and the end face 48 in the axial direction of each groove portion 47a is more magnetized than the bottom surface of the groove. It protrudes toward the outer peripheral surface of 26. The end surface 48 functions as a capturing portion that holds the adhesive 27 that has entered the adhesive groove 47 into the adhesive groove 47 when the ring magnet 28 is attached to the magnet mounting portion 26. The end face 48 as the capturing portion allows the adhesive 27 to enter the adhesive groove 47 more reliably. As described above, the number of the groove portions 47a forming the adhesive groove 47 in one row is not limited to five, and can be an arbitrary number.

  FIG. 7B is a longitudinal sectional view showing a part of a rotor as a modification, and FIG. 7C is a longitudinal sectional view showing a part of a rotor as another modification.

  7A is an arcuate surface, the rotor 16 shown in FIG. 7B is formed with a flat surface that is straight in the radial direction. ing. Thus, the cross-sectional shape of the end surface 48 as the capturing portion is not limited to the circular arc shape. In the rotor 16 shown in FIG. 7C, the adhesive grooves 47 are continuous along the axial direction, and are not divided. Thus, it is good also as the adhesive groove | channel 47 of the shape continued along the axial direction.

  FIG. 8 is a cross-sectional view showing a state in which the adhesive groove 47 shown in FIG. 5 is processed by a rolling roller. A rolling machine 50 for processing the adhesive groove 47 has two rolling rollers 51 and 52. On the outer peripheral surface of each of the rolling rollers 51 and 52, a protrusion 53 as a rolling blade corresponding to the groove shape of the groove 47a extends in the circumferential direction and is provided at a predetermined interval. In a state where the material of the shaft 18 is disposed between the two rolling rollers 51 and 52, the material of the shaft 18 is rolled by rotating both the rolling rollers 51 and 52 in the reverse direction. Two rows of adhesive grooves 47 are machined at 180 degrees in the circumferential direction in the magnet mounting portion 26 of the shaft 18 that is fed out from the manufacturing machine 50. By indexing and rotating the shaft 18 by 36 degrees and repeating the forging process five times, a total of ten adhesive grooves 47 can be processed by shifting by 36 degrees in the circumferential direction.

  FIG. 9A and FIG. 9B are cross-sectional views showing a rotor that is a modification. In the rotor 16 shown in FIG. 9A, an adhesive groove 47 is provided in the magnet mounting portion 26 so as to correspond to the circumferential central portion of only the N pole of the five N poles and the five S poles. Yes. In the rotor 16 shown in FIG. 9B, one N pole and S pole adjacent to each other in the circumferential direction and each corresponding to the N pole and S pole shifted by 180 degrees in the circumferential direction. The magnet mounting portion 26 is provided with an adhesive groove 47. As shown in FIG. 9, even if the adhesive grooves 47 are not provided corresponding to all the magnetic poles, the leakage of the adhesive 27 during the manufacture of the rotor can be prevented. However, in consideration of the balance of the magnetic flux, it is preferable to provide the adhesive groove 47 in the magnet mounting portion 26 so as to correspond to all the magnetic poles and to correspond to the circumferential central portion of the magnetic poles.

  FIG. 10 is a plan view showing the appearance of a rotor that is a modified example. In order to suppress the cogging torque that causes the vibration of the motor, the rotor 16 having the ring magnet 28 subjected to skew magnetization can be employed. In that case, the ring magnet 28 is magnetized with a skew angle inclined from one end side toward the other end side. Thus, as shown in FIG. 10, an adhesive groove 47 is formed in the magnet mounting portion 26 to which the skew magnetized ring magnet 28 is mounted. That is, according to the skew angle, the adhesive grooves 47 are inclined and along the axial direction so that the one end side and the other end side of each adhesive groove 47 are displaced in the circumferential direction. Are formed on the magnet mounting portion 26.

  In the rotor 16 of the brushless motor 10 described above, the ring magnet 28 is mounted on the magnet mounting portion 26 provided on the shaft 18. As a form of the rotor, a brushless having a shaft provided with a rotor core is provided. The present invention can also be applied to a motor. In that case, the ring magnet 28 is mounted on the outer peripheral surface of the rotor core using the outer peripheral surface of the rotor core, that is, the yoke constituting a part of the shaft as a magnet mounting portion.

  In any form, it is possible to improve the quality of the brushless motor 10 by increasing the adhesive strength of the ring magnet 28 by providing the adhesive groove 47 for accommodating the adhesive 27 in the magnet mounting portion 26 along the axial direction. In addition, the manufacturing efficiency can be improved without the adhesive leaking out of the rotor when the rotor is manufactured.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the number of magnetic poles magnetized in the rotor 16 is not limited to the illustrated 10 poles, and may be 2 poles, 4 poles, 8 poles, or the like. Furthermore, the number of the tooth portions 32 of the stator 15 around which the coil 34 is wound is not limited to nine as illustrated, and any number may be used as long as it is a multiple of 3, such as 3, 6 or the like.

11 Motor Case 13 Bracket 15 Stator 16 Rotor 17 Clearance 18 Shaft 25 Pinion Gear 26 Magnet Mount 27 Adhesive 28 Ring Magnet 31 Stator Core 32 Teeth 33 Insulator 34 Coil 47 Adhesive Groove 47a Groove 48 End Face

Claims (3)

A stator,
A rotor rotatably supported inside the stator;
A brushless motor with
The rotor is
A cylindrical shaft;
A ring magnet fixed via an adhesive to a magnet mounting portion provided on the shaft;
Consists of
A plurality of magnetic poles are magnetized adjacent to the ring magnet with different polarities in the circumferential direction,
In the magnet mounting portion, a plurality of adhesive grooves for storing the adhesive are extended along the axial direction,
The said adhesive groove | channel is a brushless motor provided corresponding to the center part of the circumferential direction of the said magnetic pole. The brushless motor according to claim 1,
The adhesive groove is divided into a plurality of groove portions at intervals in the axial direction,
The end surface of each groove part is a brushless motor which is a capturing part for fastening the adhesive. The brushless motor according to claim 1 or 2,
The brushless motor, wherein the number of the magnetic poles and the number of the adhesive grooves in the circumferential direction are the same.

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