JP5819690B2 - Motor and motor for electric power steering - Google Patents

Description

  The present invention relates to a motor including a sensor magnet for detecting a rotational position on a rotating shaft of a rotor, and an electric power steering motor.

  In a motor or the like for an electric power steering apparatus, in order to detect the rotational position of the rotor, a sensor magnet fixed to the rotation shaft of the rotor so as to be integrally rotatable, and a magnetic sensor (for example, a hall sensor) arranged to face the sensor magnet. Element, MR sensor (magnetoresistive element) and the like. Some sensor magnets are fixed with respect to a rotating shaft using a holding device (holder), as shown in Patent Document 1, for example.

  As a configuration of such a motor, for example, as shown in FIG. 11, the holder 71 has an end portion of the rotating shaft 74 inserted into a through hole 71 a that penetrates the cylindrical portion 72 and the disc portion 73. It is fixed against. The sensor magnet 75 is fixed in the fixing portion 76 of the holder 71 so that it can rotate integrally with the rotary shaft 74. A magnetic sensor 78 is provided on a circuit board 77 that is arranged to face the sensor magnet 75 at a predetermined interval in the axial direction. The magnetic sensor 78 detects a change in the magnetic field associated with the rotation of the sensor magnet 75 and outputs a rotation detection signal corresponding to the detection result. Then, the rotational position of the rotor is detected based on the rotation detection signal.

JP-T-2004-537048

  However, in the sensor magnet 75 and the magnetic sensor 78 described above, the magnetic flux generated by the sensor magnet 75 is linked to the magnetic sensor 78 at an angle with the radial line as indicated by an arrow Gz shown in FIG. That is, in addition to the magnetic flux amount being simply reduced due to leakage with the magnetic sensor 78, the amount (component) of effective magnetic flux with respect to the magnetic sensor 78 is reduced because the interlinkage magnetic flux has an angle. . In addition, since the interlinkage magnetic flux has an angle, distortion occurs in the magnetic field change on the magnetic sensor 78. As a result, the detection accuracy of the rotational position of the rotor is lowered, causing an increase in torque clip of the motor or a decrease in output.

  Further, in attaching the sensor magnet 75 using the holder 71 as described above, for example, when the holder 71 to which the sensor magnet 75 is attached is attached to the rotating shaft 74, the sensor magnet 75 and the rotating shaft 74 are closed. The air in the holder 71 to be compressed may hinder proper mounting of the holder 71 to the rotating shaft 74, or the sensor magnet 75 may fall off. Further, after the fixing, the sensor magnet 75 is always in a state of receiving stress due to the compressed air in the holder 71, and there is a possibility that the sensor magnet 75 is dropped when the motor is continuously used.

  The present invention has been made to solve the above-mentioned problems, and a first object of the present invention is to improve the detection accuracy of the rotational position of the rotor, and to reduce the torque ripple and contribute to the output improvement, and An object is to provide an electric power steering motor.

  A second object is to reduce the possibility of the sensor magnet falling off by discharging the air in the holder that fixes the sensor magnet to the rotating shaft.

In order to solve the above-mentioned problem, the invention described in claim 1 is a sensor magnet having a pair of magnetic pole portions fixed to a rotating shaft of a rotor so as to be integrally rotatable, and a rotation of the sensor magnet disposed opposite to the sensor magnet. A magnetic sensor that detects a change in the magnetic field accompanying the rotation of the rotor based on detection of the rotational position of the rotor by the magnetic sensor, and a pair of different magnetic pole portions of the sensor magnet A magnetic induction portion made of a magnetic material that extends from the opposite surface and sandwiches the magnetic sensor, and the sensor magnet is fixed via a holder fixed to the rotating shaft so as to be integrally rotatable, The end portion of the rotary shaft is press-fitted into the cylindrical portion, and is closed by mounting the sensor magnet and the rotary shaft. As a discharge means that enables discharge of air in the cylindrical portion of the cylinder, a recess is provided on the inner side surface of the cylindrical portion, and between the outer peripheral surface of the rotating shaft and the inner side surface of the cylindrical portion of the holder, A gap is formed by the concave portion, and a taper portion whose diameter decreases toward the end portion is formed on the rotation shaft. By using the taper portion, a space between the rotation shaft and the cylindrical portion of the holder is formed. A space is formed, and the concave portion is provided so as to communicate with the space formed between the rotating shaft and the cylindrical portion of the holder, and the inside and the outside of the cylindrical portion of the holder are communicated with each other. This is the gist.

  In this invention, in order to detect the rotational position of the rotor, the sensor magnet fixed to the rotating shaft so as to be integrally rotatable is made of a magnetic material extending from a pair of different magnetic pole portions and facing each other with the magnetic sensor interposed therebetween. A magnetic induction part is provided. Magnetic flux entering and exiting each magnetic pole part of the sensor magnet is induced by the magnetic induction part, and magnetic flux is generated between the magnetic induction parts sandwiching the magnetic sensor therebetween. As a result, the direction in which the magnetic flux is generated can be restricted so that the angle at which the magnetic flux is linked to the magnetic sensor is small, and leakage of the magnetic flux between the magnetic sensor and the magnetic sensor can be reduced. The amount of magnetic flux can be increased effectively. Further, since the angle of the magnetic flux linked to the magnetic sensor is reduced, the distortion of the magnetic field change on the magnetic sensor is also reduced. As a result, the detection accuracy of the rotational position of the rotor can be improved.

In addition, the sensor magnet can be more securely fixed to the rotation shaft using a holder fixed to the rotation shaft so as to be integrally rotatable.
In addition, a concave portion is provided on the inner side surface of the cylindrical portion as a discharging means that enables the discharge of air in the cylindrical portion of the holder that is closed by mounting the sensor magnet and the rotating shaft. That is, when the holder to which the sensor magnet is first attached is attached to the rotating shaft, the air in the cylindrical portion of the holder that is blocked by the sensor magnet and the rotating shaft is discharged to the outside by the recess. Thereby, since the compression of the air in the holder at the time of mounting is prevented, it is possible to reduce the possibility that the mounting of the holder to the rotating shaft is hindered or the sensor magnet falls off. In addition, even when the sensor magnet is mounted on a holder that has been mounted on the rotating shaft in advance, the air in the holder is prevented from being compressed during mounting. The possibility of hindrance can be reduced, and further, no stress based on the expansion of air due to heat is applied. In addition, after fixing, it is possible to prevent a state in which each member is constantly subjected to stress due to compressed air in the holder, and it is possible to reduce the possibility of the sensor magnet falling off when the motor is continuously used.
Further, the recess is communicated with the space formed between the rotating shaft and the cylindrical portion of the holder, and the inside of the cylindrical portion of the holder and the outside communicate with each other, whereby the air in the holder can be discharged. Moreover, it can contribute to the improvement of the freedom degree of the position which provides a recessed part in the cylinder part of a holder by utilizing the space formed by having set it as the taper part of a rotating shaft.
The invention according to claim 2 is the motor according to claim 1, wherein a plurality of the recesses are formed at equal intervals in the circumferential direction on the inner surface of the cylindrical part.
According to a third aspect of the present invention, in the motor according to the first or second aspect , the sensor magnet and the magnetic sensor are arranged to face each other in the axial direction of the rotation shaft, The gist of the invention is that the magnetic sensor and the distal end surfaces opposed in the radial direction are configured in parallel to each other.

  In the present invention, the sensor magnet and the magnetic sensor are arranged to face each other in the axial direction of the rotation shaft, and the magnetic induction portion is configured such that the tip surfaces facing the magnetic sensor and the radial direction are parallel to each other. Thereby, since the flow of uniform strong magnetic flux parallel to the radial direction is generated between the front end surfaces of the magnetic induction portions, the detection accuracy of the rotational position of the rotor can be further improved.

According to a fourth aspect of the present invention, in the motor according to any one of the first to third aspects, a corner portion of the rotating shaft that changes from an outer peripheral surface of the rotating shaft to an inclined surface in the tapered portion is an R shape. The gist of this was formed.

In this invention, the corner | angular part which changes to the slope from the outer peripheral surface of a rotating shaft in the taper part of a rotating shaft is formed in R shape, and attachment of the holder with respect to a rotating shaft becomes easy .

The invention described in 請 Motomeko 5 is the motor according to any one of claims 1 to 4, wherein the holder, the tube portion is a mounting portion of the rotary shaft is formed by at least a non-magnetic material This is the gist.

In the present invention, the holder has a cylindrical portion formed of at least a nonmagnetic material. Here, depending on the material of the rotating shaft, the magnetic flux generated from the sensor magnet may leak into the rotating shaft, and the magnetic field generated by the sensor magnet may be weakened. When the magnetic field generated by the sensor magnet becomes weak, it becomes difficult for the magnetic sensor to detect the magnetic field, so that an error occurs in the detected rotational position of the rotor, and the rotational performance of the motor controlled based on the rotational position is reduced. In the present invention, the leakage of magnetic flux from the sensor magnet to the rotating shaft is reduced by increasing the magnetic resistance between the rotating shaft and the sensor magnet formed of a non-magnetic material in the cylindrical portion of the holder. Can do.

A sixth aspect of the present invention is the motor according to any one of the first to fifth aspects, wherein there is a gap or a magnetoresistive portion made of a nonmagnetic material between the sensor magnet and the end surface of the rotating shaft. The gist is that the intervening.

  In the present invention, a gap or a magnetoresistive portion made of a nonmagnetic material is interposed between the sensor magnet and the end surface of the rotating shaft. Thereby, the leakage of the magnetic flux from a sensor magnet to a rotating shaft can be reduced by providing a magnetoresistive part and raising the magnetic resistance between a sensor magnet and a rotating shaft.

The gist of the invention according to claim 7 is that, in the motor according to any one of claims 1 to 5 , the sensor magnet and the holder are integrally formed.
In this invention, since the sensor magnet and the holder are integrally formed, an increase in the number of parts can be suppressed compared to a configuration in which the sensor magnet and the holder are independent from each other.

The gist of an eighth aspect of the present invention is the motor according to the seventh aspect , wherein the sensor magnet is a plastic magnet and is integrally formed with the holder made of a metal member.

  According to the present invention, the sensor magnet made of a plastic magnet is integrally formed with the holder of the metal member, thereby suppressing an increase in the number of parts and improving the holding force with respect to the sensor magnet and the fixing force with the rotating shaft. it can.

The gist of the ninth aspect of the present invention is that the motor according to any one of the first to eighth aspects is provided with a discriminating means for indicating a magnetization mode of the sensor magnet.
In this invention, since the discriminating means that indicates the magnetizing mode of the sensor magnet is provided, the sensor magnet that needs to be positioned with respect to the rotor can be easily attached at an appropriate position.

The invention according to claim 1 0, in the motor according to any one of claims 1 to 9, wherein the rotor, together with the field magnet which functions as one of the magnetic poles are more arranged in the circumferential direction of the rotor core The gist is that the pseudo magnetic poles integrally formed with the rotor core are arranged between the magnets, and the pseudo magnetic pole functions as the other magnetic pole.

According to the present invention, in a motor having a consequent pole type (half magnet type) rotor, in which the magnetic field of the sensor magnet is often distorted, the effects of the motor according to any one of claims 1 to 9 are obtained. be able to. In particular, when applied to the inventions of claims 5 and 6 , the magnetic resistance of the sensor magnet is suppressed from being distorted by increasing the magnetic resistance between the sensor magnet and the rotating shaft.

The invention of claim 1 1, in the motor according to any one of claims 1 to 1 0, annular stator facing the rotor in a radial direction is housed in the case member of ferromagnetic material, The gist of the invention is that the sensor magnet is fixed to the rotating shaft outside the case member.

  In this invention, the rotor and the stator are accommodated in a case member made of a ferromagnetic material, and the sensor magnet is fixed to the rotating shaft outside the case member. As a result, among the magnetic fluxes generated from the rotor field magnets and the like, for example, the magnetic fluxes that attempt to flow through the rotating shaft can easily return to the magnets through the case member of the ferromagnetic material. That is, the sensor magnet has a ferromagnetic case member interposed between the rotor and the stator, thereby reducing the influence of the magnetic flux from the rotor and the stator and suppressing the distortion of the magnetic field.

According the invention described in claim 1 2 is an electric power steering motor using the structure of the motor according to any one of claims 1 to 1 1.
According to this invention, the rotational drive is improved by improving the detection accuracy of the rotational position of the rotor as a structure that effectively increases the amount of magnetic flux interlinking the magnetic sensor by guiding the magnetic flux of the sensor magnet into the magnetic induction portion. It has high applicability to a power steering motor that is required to reduce noise and reduce noise with high accuracy.

ADVANTAGE OF THE INVENTION According to this invention, the detection accuracy of the rotation position of a rotor can be improved, the motor which can contribute to reduction of a torque ripple, and an output improvement, and the motor for electric power steering can be provided.

Further, it is possible to discharge the air in the holder for fixing the sensor magnet on the rotation axis sensor magnet to reduce the possibility of falling off.

(A) is an axial sectional view of the motor, (b) is an enlarged view of the holder and sensor magnet of (a). The radial direction sectional view of a motor. The exploded perspective view of a holder and a sensor magnet. The enlarged view of the holder and sensor magnet of another form. The enlarged view of the holder and sensor magnet of another form. (A) is a perspective view of the holder of another form, (b) is a top view of a holder and a sensor magnet, (c) is AA sectional drawing in (b). (A) is a perspective view of the holder of another form, (b) is a top view of a holder and a sensor magnet, (c) is BB sectional drawing in (b). (A) (b) is sectional drawing of the holder and sensor magnet of another form. Sectional drawing of the holder and sensor magnet of another form. Sectional drawing of the holder and sensor magnet of another form. The enlarged view of the conventional holder and a sensor magnet.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1A, the motor M of this embodiment is used for an electric power steering apparatus (EPS) and is an inner rotor type brushless motor. The motor case 1 is made of a ferromagnetic material, and includes a case main body 2 and an end frame 3 assembled to the case main body 2. The case main body 2 has a bottomed cylindrical shape in which a cylindrical tubular portion 2a and a bottom portion 2b that substantially closes the proximal end side in the axial direction of the tubular portion 2a are integrally formed. The opening on the front end side of the case body 2 is closed by the substantially disc-shaped end frame 3.

  The bottom portion 2b is formed with a bearing housing portion 2c that is recessed toward the base end side in the central portion in the radial direction. The bearing housing portion 2c has a through hole 2d penetrating in the axial direction at the center of the bottom. An annular bearing 4 is accommodated in the bearing accommodating portion 2c. The end frame 3 is formed with a bearing housing portion 3a that is recessed toward the tip side at the radial center. The bearing housing 3a is formed with a through hole 3b penetrating in the axial direction at the center of the bottom. An annular bearing 5 is accommodated in the bearing accommodating portion 3a. And each bearing 4 and 5 supports the rotating shaft 22 of the rotor 21 mentioned later so that rotation is possible.

  Inside the motor case 1, a cylindrical stator 11 is fixed to the inner peripheral surface of the cylindrical portion 2a. As shown in FIGS. 1A and 2, the stator 11 includes a substantially cylindrical stator core 12 formed by laminating a plurality of magnetic metal plate materials. The stator core 12 includes a cylindrical inner fitting portion 12a and teeth 12b extending radially inward from the inner peripheral surface of the inner fitting portion 12a. Sixty teeth 12b are formed in the circumferential direction of the stator core 12 at equiangular intervals (6 ° intervals in this embodiment), and slots S are formed between the teeth 12b. The stator 11 according to the present embodiment is a so-called stator 11 in which a segment SG made of an elongated conductor plate is inserted into each slot S from the base end side in the axial direction to the tip end side, and the segments SG are joined to each other according to a predetermined rule. An SC winding 13 is configured. The SC winding 13 is composed of three-phase windings of U phase, V phase, and W phase. The stator 11 has an inner fitting portion 12a fixed to the inner peripheral surface of the cylindrical portion 2a. A rotor 21 is arranged inside the stator 11 in the radial direction.

  The rotor 21 includes a columnar rotating shaft 22 formed of a nonmagnetic metal (for example, stainless steel (SUS)), a rotor core 23 fixed to the rotating shaft 22, and a field disposed with respect to the rotor core 23. And a magnet 24. The rotating shaft 22 is made of a nonmagnetic metal having a larger magnetic resistance than the rotor core 23.

  The rotor core 23 includes a substantially cylindrical core fixing portion 23a formed by laminating a plurality of magnetic metal plate materials, and five pseudo magnetic poles 23b protruding radially outward from the outer peripheral surface of the core fixing portion 23a. Yes. The rotor core 23 is fixed to the rotation shaft 22 so as to be integrally rotatable with the stator 11 by the press-fitting of the rotation shaft 22 into a fixing hole 23c formed in the central portion in the radial direction of the core fixing portion 23a. Opposite to.

  The pseudo magnetic poles 23b are formed integrally with the core fixing portion 23a, and are formed at equiangular intervals (72 ° intervals in the present embodiment) at intervals in the circumferential direction on the outer periphery of the core fixing portion 23a. On the outer periphery of the rotor core 23, magnets 24 are provided between the pseudo magnetic poles 23 b, and a total of five magnets 24 are arranged. Each magnet 24 has a substantially rectangular shape extending in the axial direction, and the length in the axial direction is substantially equal to the length in the axial direction of the rotor core 23. On the radially inner side of each pseudo magnetic pole 23b of the rotor core 23, substantially trapezoidal through-holes 25 having short sides on the inner side are formed, and five are formed in the circumferential direction like the pseudo magnetic pole 23b.

  The inner peripheral side surface 24a on the radially inner side of the magnet 24 is fixed to the outer peripheral surface of the core fixing portion 23a. The circumferential width of the magnet 24 is formed shorter than the circumferential width of the portion between the pseudo magnetic poles 23b on the outer peripheral surface of the rotor core 23, and each magnet 24 is separated from the pseudo magnetic poles 23b on both sides in the circumferential direction. Each magnet 24 is magnetized so that the outer peripheral side surface 24b side is an N pole and the inner peripheral side surface 24a side is an S pole. The pseudo magnetic pole 23 b functions as a pseudo S pole with respect to the N pole magnet 24. That is, the rotor 21 of this embodiment is a continuous pole type (half magnet type) rotor.

  As shown in FIGS. 1 (a) and 1 (b), the rotating shaft 22 of the rotor 21 is pivotally supported by the bearing 5 in the bearing housing portion 3a on the tip side, and from the through hole 3b to the outside of the end frame 3. Protruding. A connecting portion 6 for connecting to an external mechanism such as a speed reducer is fixed to the protruding tip end portion (output side end portion) of the rotating shaft 22. Further, the rotary shaft 22 is pivotally supported by the bearing 4 accommodated in the bearing accommodating portion 2c on the proximal end side, and protrudes outside the case main body portion 2 from the through hole 2d. A holder 31 is fixed to the protruding proximal end portion of the rotary shaft 22, and a sensor magnet 32 for detecting the rotational position of the rotary shaft 22 (rotor 21) is held in the holder 31. The rotating shaft 22 has a truncated cone shape in which the end portion on the proximal end side is reduced in diameter toward the distal end.

  A drive circuit device 41 is fixed to the base end portion of the case body 2. The drive circuit device 41 includes a bottomed cylindrical storage case 42 and a circuit board 43 stored in the storage case 42. The housing case 42 is assembled to the case body 2 so that the opening thereof is closed by the bottom 2b, so that the base end portion of the rotating shaft 22, the holder 31, and the sensor magnet 32 are contained in the housing case 42. Is housed in. The circuit board 43 is disposed so as to be parallel to the sensor magnet 32 in the radial direction. A magnetic sensor 44 disposed opposite to the sensor magnet 32 at a predetermined interval in the axial direction is provided on the substrate in the central portion in the radial direction of the circuit board 43. The magnetic sensor 44 is, for example, an MR sensor (magnetoresistive element). A detection circuit (not shown) electrically connected to the magnetic sensor 44 and a drive control circuit (not shown) for controlling the supply of current to the SC winding 13 of the stator 11 are provided on the circuit board 43. ing. The drive control circuit is connected to the detection circuit and is connected to an external power supply device.

  Further, output terminals 46 for supplying electric power to each phase of the SC winding 13 are formed on the substrate on the radially outer side of the circuit board 43. Each output terminal 46 is provided at a position facing the power receiving terminal (not shown) provided in the SC winding 13 for each phase in the axial direction. The lead wires 47 led out from the power receiving terminals for each phase pass through the through holes 2e formed in the bottom 2b of the case body 2 and are connected to the output terminals 46 for each phase on the circuit board 43, respectively. .

  As shown in FIGS. 3 and 1B, the holder 31 fixed to the base end portion of the rotating shaft 22 is made of nonmagnetic metal (stainless steel (SUS), aluminum, etc.), and the rotating shaft 22 is fixed. A cylindrical portion 33 as a mounting portion, a disc portion 34 formed to extend radially outward from a proximal end of the cylindrical portion 33, and a fixed portion 35 formed on the outer periphery of the disc portion 34. Has been. A press-fit hole 31 a penetrating in the axial direction is formed at the center of the cylindrical portion 33 and the disc portion 34.

  A pair of fixing portions 35 extend from the outer peripheral surface 34a of the disc portion 34 to the side opposite to the cylindrical portion 33, and are provided in a pair at 180 ° facing positions. Each fixing portion 35 has an arc shape, and a notch 35 a is formed between the fixing portions 35. A disk-shaped sensor magnet 32 is disposed on the inner side in the radial direction of each fixed portion 35, and a through hole 32 a that penetrates the front and back in the axial direction is formed at the center of the sensor magnet 32. The sensor magnet 32 is disposed so that the outer peripheral surface 32b of the sensor magnet 32 is fitted into the inner peripheral surface 35b of the fixed portion 35, and the end surface 32c is in contact with the disk portion 34. For example, an adhesive made of a nonmagnetic material is used. The outer peripheral surface 32b and the inner peripheral surface 35b of the fixing portion 35 are bonded and fixed to the end surface 32c and the disc portion 34, respectively. The sensor magnet 32 fixed to the fixing portion 35 is arranged so that the end surface 32d is substantially the same height as the end surface 35c of the fixing portion 35. The holder 31 and the sensor magnet 32 are fixed to the rotary shaft 22 so as to be integrally rotatable when the proximal end portion of the rotary shaft 22 is press-fitted into the press-fitting hole 31 a of the holder 31. At this time, the end surface 32 c of the sensor magnet 32 and the end surface 22 a of the rotating shaft 22 are fixed in a state where a gap 37 is generated in the press-fitting hole 31 a of the holder 31.

  The sensor magnet 32 is magnetized with a pair of N-pole magnetized portions 38 and S-pole magnetized portions 39 so that the magnetic poles are switched in the circumferential direction (rotational direction). Magnetic induction portions 51 and 52 are fixed to the outer peripheral surface 32b of the magnetized portions 38 and 39 of the sensor magnet 32, respectively. The magnetic induction portions 51 and 52 are made of a ferromagnetic material (iron plate or the like), and include wall portions 51a and 52a formed in the axial direction, and flat portions 51b and 52b formed at end portions of the wall portions 51a and 52a. It is configured. The walls 51 a and 52 a are formed in an arc shape having the same curvature as the outer peripheral surface 32 b (fixed portion 35) of the sensor magnet 32. The flat portions 51b and 52b are formed by flat surfaces extending in a rectangular shape radially inward while closing the substantially semicircular shape of the protruding tips of the wall portions 51a and 52a. The front end surfaces 51d and 52d of the flat portions 51b and 52b are formed along a direction orthogonal to the protruding direction of the flat portions 51b and 52b.

  In such magnetic induction portions 51 and 52, the wall portions 51 a and 52 a are fitted into the cutout portions 35 a of the fixing portion 35, and the inner peripheral surfaces 51 c and 52 c of the wall portions 51 a and 52 a are the outer peripheral surfaces of the sensor magnet 32. It is fixed to 32b with an adhesive (preferably an adhesive having magnetism). Therefore, the magnetic induction portions 51 and 52 rotate integrally with the sensor magnet 32 when the holder 31 is fixed to the rotating shaft 22. The magnetic guide portions 51 and 52 have the axial length L of the wall portions 51a and 52a set so that the flat portions 51b and 52b face each other with the magnetic sensor 44 interposed therebetween in the radial direction. .

  In the motor M configured as described above, the magnetic sensor 44 shown in FIG. 1A detects a change in the magnetic field of the sensor magnet 32 accompanying the rotation of the rotary shaft 22, and the rotation detection signal corresponding to the detection result is detected as described above. Output to the circuit. The detection circuit detects the rotational position of the rotor 21 based on the rotation detection signal and outputs it to the drive control circuit. Then, the drive control circuit generates an appropriate drive current from time to time based on the detected rotational position and the like, and supplies the drive current from the output terminal 46 to the SC winding 13 of the stator 11 via the lead wire 47, and the rotor. 21 is driven to rotate.

Next, the operation of this embodiment will be described.
As shown in FIG. 1 (b), the magnetic induction portions 51 and 52 made of a ferromagnetic material disposed in contact with the sensor magnet 32 are formed by flat portions 51b and 52b provided on the projecting tip side of the walls 51a and 52a. The tip surfaces 51d and 52d are provided so as to face the magnetic sensor 44 in the radial direction. The tip surfaces 51d and 52d are provided so as to be parallel to the direction perpendicular to the protruding direction of the flat portions 51b and 52b (that is, the distance between the tip surfaces is the same). Therefore, the magnetic flux generated by the sensor magnet 32 is guided by the magnetic induction portions 51 and 52 corresponding to the magnetized portions 38 and 39, and the magnetic sensor from the protruding tips (tip surfaces 51d and 52d of the flat portions 51b and 52b). 44 is efficiently generated (leakage is less). Moreover, since the front end surfaces 51d and 52d of the magnetic induction portions 51 and 52 are formed in parallel with each other with the magnetic sensor 44 interposed therebetween, as shown by the arrow Ga in FIG. A parallel and uniform strong magnetic flux that sandwiches the magnetic sensor 44 in the radial direction flows between the front end surfaces 51d and 52d. Therefore, the angle at which the magnetic flux is linked to the magnetic sensor 44 becomes extremely small. From these, the amount of magnetic flux interlinked with the magnetic sensor 44 can be effectively increased, and the distortion of the magnetic field change on the magnetic sensor 44 is also extremely reduced, so that the detection accuracy of the magnetic sensor 44 is improved. Yes.

  As for the attachment of the sensor magnet 32 portion, for example, when the holder 31 to which the sensor magnet 32 is first attached is attached to the rotary shaft 22 through the through hole 32a formed at the center thereof, the sensor magnet 32 is attached. The air in the press-fit hole 31 a closed by the magnet 32 and the rotating shaft 22 is discharged to the outside through the through hole 32 a of the sensor magnet 32. That is, since the compression of the air in the press-fitting hole 31a at the time of mounting is prevented, the possibility of hindering proper mounting of the holder 31 to the rotating shaft 22 or dropping of the sensor magnet 32 is reduced. . Further, even when the sensor magnet 32 is mounted on the holder 31 previously mounted on the rotary shaft 22, the air in the press-fitting hole 31a at the time of mounting is prevented from being compressed. The possibility of hindering proper attachment to 31 can also be reduced, and furthermore, stress based on the expansion of air due to heat is not applied. Further, since the state where the sensor magnet 32 is always subjected to stress due to the compressed air in the holder 31 (inside the press-fit hole 31a) after fixing is prevented, the sensor magnet 32 when the motor M is continuously used is prevented. The possibility of dropping off is also reduced.

  Further, regarding the magnetic improvement of the holder 31 portion, the whole including the cylindrical portion 33 for mounting on the rotating shaft 22 is formed of a nonmagnetic material, and the end surface 32d of the sensor magnet 32 and the end surface 22a of the rotating shaft 22 A gap 37 is provided between them. Here, depending on the material of the rotating shaft 22, the magnetic flux generated from the sensor magnet 32 may leak into the rotating shaft 22, and the magnetic field generated by the sensor magnet 32 may be weakened. If the magnetic field generated by the sensor magnet 32 becomes weak, it becomes difficult to detect the magnetic field by the magnetic sensor 44, so that an error occurs in the detected rotational position of the rotor 21, and consequently the rotational performance of the motor M controlled based on the rotational position. Decreases. On the other hand, in the present embodiment, the holder 31 is formed of a nonmagnetic material, and the gap 37 is provided between the sensor magnet 32 and the rotating shaft 22 to increase the magnetic resistance between them, thereby rotating the sensor magnet 32. Magnetic flux leakage to the shaft 22 is reduced, and this also improves the detection accuracy of the magnetic sensor 44.

  Further, the motor M of the present embodiment includes a so-called continuous pole type rotor 21. Here, in the rotor 21 having the continuous pole type structure, the pseudo magnetic pole 23b functions as a magnetic pole different from the magnet 24, but is not actually a magnet. In this way, the magnetic flux of the magnet 24 flows into the rotating shaft 22 due to the effect of the pseudo magnetic pole 23b having no magnetic force forcing (induction) as a magnetic pole, and the cylindrical portion 33 of the holder 31 holding the sensor magnet 32 is fixed. There is a possibility that the part of the rotating shaft 22 is magnetized. As a result, the magnetic field of the sensor magnet 32 is distorted, and the detection accuracy of the rotational position of the rotor 21 by the magnetic sensor 44 may be reduced. On the other hand, in the present embodiment, the holder 31 is formed of a non-magnetic material, and a gap 37 (magnetic resistance portion) is provided between the sensor magnet 32 and the rotary shaft 22 so that the sensor can be detected by the magnetized rotary shaft 22. The distortion of the magnetic field of the magnet 32 is suppressed, and this also improves the detection accuracy of the magnetic sensor 44.

  Further, as shown in FIG. 1A, the rotor 21 and the stator 11 are accommodated in the motor case 1 made of a ferromagnetic material, and the sensor magnet 32 is fixed to the rotating shaft 22 outside the motor case 1. Yes. Thereby, for example, the magnetic flux of the magnet 24 that has flowed into the rotary shaft 22 from the rotor core 23 is absorbed from the bearing housing portion 2 c (through hole 2 d portion) of the motor case 1 adjacent to the rotary shaft 22, and from the magnet 24 and the rotor core 23. Magnetic flux (leakage magnetic flux) generated in the air is also absorbed by the bottom 2b of the motor case 1 and the like. That is, most of the magnetic flux generated by the magnet 24 flows in a magnetic circuit formed at a location unrelated to the sensor magnet 32, and this also improves the detection accuracy of the magnetic sensor 44.

Next, characteristic effects of the present embodiment will be described.
(1) In the motor M of this embodiment, the holder 31 is fixed to the base end portion of the rotating shaft 22, and the sensor magnet 32 is fixed to the fixing portion 35 of the holder 31. On the circuit board 43 in the drive circuit device 41 of the motor M, a magnetic sensor 44 is provided so as to face the sensor magnet 32 at a predetermined interval in the axial direction. The sensor magnet 32 is provided with magnetic induction portions 51 and 52 made of a ferromagnetic material on the outer peripheral surface 32b of the magnetized portions 38 and 39. The magnetic induction portions 51 and 52 are arranged in the radial direction with the magnetic sensor 44. It is provided so as to oppose. Therefore, the magnetic flux generated by the sensor magnet 32 is induced by the magnetic induction portions 51 and 52 corresponding to the respective magnetization portions 38 and 39, and between the magnetic induction portions 51 and 52 with the magnetic sensor 44 interposed therebetween (flat Magnetic flux is generated between the tip surfaces 51d and 52d of the portions 51b and 52b (see FIG. 1B). As a result, the direction of magnetic flux generation can be regulated so that the angle at which the magnetic flux interlinks with the magnetic sensor 44 is a small magnetic field, and leakage of magnetic flux between the magnetic sensor 44 and the magnetic sensor 44 can be reduced. The amount of magnetic flux interlinking can be effectively increased. Further, since the angle of the magnetic flux interlinking with the magnetic sensor 44 is reduced, the distortion of the magnetic field change on the magnetic sensor 44 can also be reduced. As a result, the detection accuracy of the rotational position of the rotor 21 can be improved, and the torque ripple of the motor M can be reduced and the output can be improved. Further, such a motor M has high applicability to a power steering motor that is highly accurate in rotational drive and that is desired to reduce noise and reduce noise.

  The sensor magnet 32 is fixed by the holder 31 so as to face the end surface 22 a of the rotating shaft 22. Here, in the configuration shown in Patent Document 1 described above, the sensor magnet 32 is formed in an annular shape, and the sensor magnet 32 does not face the end surface 22 a of the rotating shaft 22. In such a configuration, it is necessary to arrange the magnetic sensor 44 so as to correspond to the position accompanying rotation of the magnetized portions 38 and 39 of the sensor magnet 32, and high-accuracy position adjustment is required. On the other hand, in the present embodiment, the position adjustment is facilitated by arranging the magnetic sensor 44 on the axis of the rotating shaft 22 with respect to the sensor magnet 32 fixed facing the end surface 22a of the rotating shaft 22.

  (2) In each of the magnetic induction portions 51 and 52, tip surfaces 51d and 52d that face the magnetic sensor 44 in the radial direction are formed in parallel to each other. As a result, a uniform strong magnetic flux parallel to the radial direction is generated between the front end surfaces 51d and 52d of the flat portions 51b and 52b of the magnetic induction portions 51 and 52, so that the detection accuracy of the rotational position of the rotor 21 is further improved. Can be improved.

  (3) The sensor magnet 32 is fixed to the rotary shaft 22 via a holder 31 fixed to the rotary shaft 22 so as to be integrally rotatable. Thus, for example, the sensor magnet 32 can be more securely fixed to the rotary shaft 22 than the configuration in which the sensor magnet 32 is directly fixed to the end surface 22a of the rotary shaft 22, and the sensor magnet 32 is damaged. The possibility of doing so can be reduced.

  (4) The sensor magnet 32 is formed with a through hole (discharge means) 32 a that allows the air in the holder 31 that is blocked by the mounting of the sensor magnet 32 and the rotating shaft 22 to be discharged. As a result, the possibility of the sensor magnet 32 dropping off can be reduced, and the sensor magnet 32 can be appropriately attached to the holder 31.

  (5) The holder 31 is entirely made of a nonmagnetic material, including the cylindrical portion 33 for mounting on the rotary shaft 22. Thereby, the leakage of the magnetic flux from the sensor magnet 32 to the rotating shaft 22 can be reduced by increasing the magnetic resistance between the sensor magnet 32 and the rotating shaft 22. This also improves the detection accuracy of the magnetic sensor 44.

  (6) The holder 31 is provided with a gap 37 serving as a magnetoresistive portion between the press-fitted rotary shaft 22 and the sensor magnet 32 fixed to the fixing portion 35 in the press-fitting hole 31a. Thereby, the leakage of the magnetic flux from the sensor magnet 32 to the rotating shaft 22 can be reduced by increasing the magnetic resistance between the sensor magnet 32 and the rotating shaft 22. This also improves the detection accuracy of the magnetic sensor 44.

  (7) In this embodiment, in the motor M having the continuous pole type rotor 21 in which the magnetic field of the sensor magnet 32 is often distorted, the holder 31 is formed of a nonmagnetic material, By providing the gap 37 (magnetic resistance part) between the rotating shaft 22 and the magnetized rotating shaft 22, the magnetic field of the sensor magnet 32 is suppressed from being distorted. This also improves the detection accuracy of the magnetic sensor 44.

  (8) The rotor 21 and the stator 11 are accommodated in a motor case 1 (case member) made of a ferromagnetic material, and the sensor magnet 32 is fixed to the rotating shaft 22 outside the motor case 1. As a result, the sensor magnet 32 has the ferromagnetic motor case 1 interposed between the rotor 21 and the stator 11, thereby reducing the influence of magnetic flux from the rotor 21 and the stator 11 and suppressing distortion of the magnetic field. Is done. Since the portion of the rotating shaft 22 where the sensor magnet 32 (holder 31) is fixed is suppressed from being magnetized, the magnetic field of the sensor magnet 32 is suppressed from being distorted due to the influence of the magnetized rotating shaft 22. As a result, the detection accuracy of the magnetic sensor 44 can be improved.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the sensor magnet 32 is fixed to the rotating shaft 22 using the holder 31, but the sensor magnet 32 may be directly fixed to the end surface 22 a of the rotating shaft 22 as shown in FIG. 4. For example, if the sensor magnet 32 is fixed to the end surface 22 a of the rotating shaft 22 with an adhesive 61 made of a nonmagnetic material, the adhesive 61 functions as a magnetoresistive portion between the rotating shaft 22 and the sensor magnet 32. It can also be made.

  -In the said embodiment, the shape of the holder 31 is an example and may be changed suitably. For example, as shown in FIG. 5, it is good also as a structure which forms the fixing | fixed part 35 cyclically | annularly and mounts the sensor magnet 32 with the magnetic induction parts 51 and 52 inside it. Further, although the entire holder 31 is formed of a nonmagnetic material, only a part thereof, for example, the cylindrical portion 33 (mounting portion) may be formed of a nonmagnetic material.

  In the above embodiment, the shape of the magnetic induction portions 51 and 52 is an example, and may be changed as appropriate. For example, the wall portions 51a and 52a and the flat portions 51b and 52b are plate-shaped, but may be changed to other shapes such as a column shape.

  In the above embodiment, the front end surfaces 51d and 52d are provided so as to be parallel to each other in the direction orthogonal to the protruding direction of the flat portions 51b and 52b, but are provided so as to be parallel to each other in other radial directions, for example. May be.

  In the above embodiment, the magnetic induction portions 51 and 52, the sensor magnet 32, and the holder 31 are separately configured and bonded and fixed, but they may be fixed to each other using a fixing method other than bonding, such as press-fitting and locking. Good. Alternatively, the holder 31 may be molded and integrated with the magnetic induction portions 51 and 52 and the sensor magnet 32 in contact with each other. Further, the magnetic induction portions 51 and 52 and the holder 31 may be made of magnetic resin and molded integrally with the sensor magnet 32. In this case, an increase in the number of parts can be suppressed with respect to the configuration in which the members are independent from each other. Alternatively, the sensor magnet 32 may be constituted by a so-called plastic magnet formed by including a magnetic material in a resin material, and may be attached to the holder 31 such as a metal member by integral molding. Thereby, while suppressing the increase in a number of parts, the retention strength with respect to the sensor magnet 32 and the fixing force with respect to the rotating shaft 22 can be improved.

  In the above embodiment, the magnetic induction portions 51 and 52 are fixed to the outer peripheral surface 32b of the sensor magnet 32. However, the present invention is not limited to this. For example, the magnetic induction portions 51 and 52 are fixed on the end surfaces 32d of the magnetized portions 38 and 39 of the sensor magnet 32. Also good.

In the above embodiment, the through hole 32a is provided in the sensor magnet 32 as the discharging means for discharging the air in the holder 31 (press-fit hole 31a), but the present invention is not limited to this.
For example, as shown in FIG. 6A, a concave portion 62 may be provided in the cylindrical portion (mounting portion) 33 of the holder 31. The cylindrical portion 33 is formed with a plurality (three in FIG. 6A) of concave portions 62 each having a concave inner surface 63 in the circumferential direction. Each recess 62 is formed along the axial direction with a constant width in the circumferential direction, and the base end side (sensor magnet 32 side) in the axial direction has an arc shape. As shown in the enlarged view of FIG. 6C, a gap 64 is formed between the outer peripheral surface 22b of the rotating shaft 22 and the inner side surface 63 of the recess 62, and the inside of the holder 31 is communicated with the outside. . In this case, a frustoconical taper portion 65 whose diameter decreases toward the tip is formed at the end of the rotating shaft 22, and the recess 62 communicates with a space 66 formed by the taper portion 65. It is provided as follows. Thereby, the air in the holder 31 can be discharged through the concave portion 62 that communicates the inside of the holder 31 formed in the cylindrical portion 33 with the outside. Further, by using the space 66 formed by the tapered portion 65 of the rotating shaft 22, it is possible to contribute to an improvement in the degree of freedom of the position where the concave portion 62 formed in the cylindrical portion 33 of the holder 31 is provided. Further, the rotating shaft 22 is formed with an R-shaped corner portion 67 that changes from the outer peripheral surface 22b of the rotating shaft 22 to the inclined surface in the tapered portion 65 (see the enlarged view of FIG. 6C). Thereby, attachment of the holder 31 with respect to the rotating shaft 22 becomes easy. Incidentally, in the above-described configuration, the through hole 32a of the sensor magnet 32 can be omitted.

  In the above-described configuration, the cylindrical portion 33 is not formed with the concave portion 62 up to the axial base end side (sensor magnet 32 side) portion. By adopting such a configuration, a sufficient fixing force with the rotating shaft 22 can be secured, and for example, when the sensor magnet 32 is made of a plastic magnet and attached to the metal member holder 31 by integral molding, The molten plastic member at the time of molding can be prevented from leaking through the recess 62. Accordingly, the inside of the holder 31 and the recess 62 are communicated with each other in cooperation with the tapered portion 65 of the rotating shaft 22.

  For example, as shown in FIGS. 7A to 7C, even if the through hole 33 a is formed in the cylindrical portion 33 of the holder 31, the discharge means can be simply configured to discharge the air in the holder 31. . In this case, the through hole 33a is formed so as to communicate with the space 66 formed by providing the tapered portion 65.

  Further, for example, as illustrated in FIG. 8A, a through hole 22 c may be formed in the rotating shaft 22. The through-hole 22c of the rotating shaft 22 shown in FIG. 8A is formed in a substantially central portion of the rotating shaft 22 along the axial direction, is bent in a perpendicular direction at a predetermined position, and penetrates to the outer peripheral surface 22b. The inside 31 communicates with the outside. Even in such a configuration, the same effect as described above can be obtained. For example, as shown in FIG. 8B, even if the through hole 22c is formed by penetrating the end surface 22a on the proximal end side and the end surface 22d on the distal end side of the rotating shaft 22, the same effect as described above can be obtained. Can be obtained.

  For example, as shown in FIG. 9, a through hole 35 d is formed in the base end portion of the fixing portion 35 of the holder 31, and a recess 32 e is formed in the end surface 32 c of the sensor magnet 32 so as to communicate with the holder 31. The inside air may be discharged. In addition, as shown in FIG. 9, when the magnetic induction part 51 intervenes between the recessed part 32e and the through-hole 35d, it corresponds by forming the through-hole 51e in itself. Even in such a configuration, the same effect as described above can be obtained. In addition, the through hole 51e provided in the magnetic induction part 51 can be omitted by providing the recess 32e and the through hole 35d so as to be shifted from the magnetic induction part 51. The position where the through hole 35d is provided is not limited to the fixed portion 35, and may be formed in another portion (for example, the disc portion 34) that holds the sensor magnet 32.

  For example, as shown in FIG. 10, a recess 22 e that communicates the inside of the holder 31 with the outside may be formed on the outer peripheral surface 22 b of the rotating shaft 22. Even in such a configuration, the same effect as described above can be obtained.

  In the configuration including the above-described embodiment and the discharge means shown in FIGS. 5 to 10, the above-described effect (the air in the holder 31 can be discharged) can be obtained even if the magnetic induction portions 51 and 52 are omitted. . In addition, the number, shape, configuration, and the like of the discharging means described above are examples, and these and combinations thereof may be changed as appropriate. For example, both the through hole 32a of the sensor magnet 32 and the through hole 33a of the cylindrical portion 33 may be provided.

  In the above-described embodiment, a determination unit that indicates the magnetization mode of the sensor magnet 32 may be provided. For example, the holder 31 shown in FIGS. 6A to 6C is provided with an annular flange portion 68 formed to extend radially outward from the distal end portion of the fixing portion 35, and the outer peripheral surface of the flange portion 68 is A shape (D cut shape) cut linearly in a direction perpendicular to the radial direction is formed. The flat surface 68 a generated thereby is provided in accordance with the position of the N pole magnetized portion 38 of the sensor magnet 32. Here, in the correction processing of the magnetic pole positions of the sensor magnet 32 and the rotor 21 after the sensor magnet 32 is attached, there is a possibility that problems such as motor lock and reverse rotation may occur if the magnetic pole positions are greatly deviated. Therefore, in this correction process, the magnetic pole positions of the sensor magnet 32 and the rotor 21 need to be within a predetermined range. Therefore, since the flat surface 68a functions as a discriminating means for discriminating the mounting position of the sensor magnet 32 in the rotational direction, the sensor magnet 32 that needs to be positioned with respect to the rotor 21 can be easily mounted at an appropriate position. As a result, the correction process can be performed without causing a problem. Note that the shape, configuration, etc. of the discriminating means are examples, and may be changed as appropriate.

-In the said embodiment, the shape of the sensor magnet 32 made into disk shape is an example, You may change suitably, for example, you may form in a rectangular parallelepiped.
In the above embodiment, the magnetoresistive portion may be configured by filling the gap 37 with a nonmagnetic resin or the like.

In the above embodiment, the MR sensor is used as the magnetic sensor 44, but another sensor such as a Hall element may be used.
In the above embodiment, the number of magnetic poles of the sensor magnet 32 and the stator 11 is an example, and may be changed as appropriate.

  In the above-described embodiment, the present invention is applied to the so-called continuous pole type (half magnet type) rotor 21, but may be applied to a full magnet type rotor in which all magnetic poles are configured by magnets.

  In the above-described embodiment, the slot S of the stator 11 is composed of an SC winding in which an elongated conductor plate is appropriately joined. However, the coil is not limited to this, and for example, a flexible conductor wire is wound. You may comprise a coil by winding (concentrated winding, distributed winding, etc.). Further, the coil to be wound is not limited to three phases, and may be appropriately changed to a single layer or other plural phases.

In the above embodiment, the present invention is applied to the motor M for the electric power steering device (EPS), but may be applied to a motor used for other purposes.
Next, a technical idea that can be grasped from the above embodiment and another example will be added below.

(A) a sensor magnet fixed to the rotating shaft of the rotor via a holder so as to be integrally rotatable;
A magnetic sensor that is disposed opposite to the sensor magnet and detects a change in the magnetic field accompanying the rotation of the sensor magnet,
A motor for rotationally driving the rotor based on detection of a rotational position of the rotor by the magnetic sensor;
Discharging means that allows the air in the holder, which is blocked by mounting of the sensor magnet and the rotating shaft, to be discharged is provided in at least one of the sensor magnet, the holder, and the rotating shaft. Motor.

  According to this configuration, at least one of the sensor magnet, the holder, and the rotating shaft is provided with the discharging unit that allows the air in the holder that is blocked by the mounting of the sensor magnet and the rotating shaft to be discharged. That is, when the holder to which the sensor magnet is first attached is attached to the rotation shaft, the air in the holder closed by the sensor magnet and the rotation shaft is discharged to the outside by the discharge means. Thereby, since the compression of the air in the holder at the time of mounting is prevented, it is possible to reduce the possibility that the mounting of the holder to the rotating shaft is hindered or the sensor magnet falls off. In addition, even when the sensor magnet is mounted on a holder that has been mounted on the rotating shaft in advance, the air in the holder is prevented from being compressed during mounting. The possibility of hindrance can be reduced, and further, no stress based on the expansion of air due to heat is applied. In addition, after fixing, it is possible to prevent a state in which each member is constantly subjected to stress due to compressed air in the holder, and it is possible to reduce the possibility of the sensor magnet falling off when the motor is continuously used.

(B) In the motor described in (a) above,
The motor according to claim 1, wherein the discharging means includes a sensor magnet, a mounting portion of the holder with the rotating shaft, and a through-hole formed in at least one of the rotating shafts.

  According to this configuration, the air in the holder can be discharged through the through hole formed in at least one of the sensor magnet, the holder mounting portion, and the rotating shaft. Further, the discharging means can be configured simply.

(C) In the motor described in (a) above,
The motor according to claim 1, wherein the discharging means is formed of a recess formed in a mounting portion of the holder and communicating the inside of the holder with the outside.

According to this structure, the air in a holder can be discharged | emitted through the recessed part which connects the inside of the holder formed in the mounting part of the holder, and the exterior. Further, the discharging means can be configured simply.
(2) In the motor described in (a) above,
A taper portion whose diameter is reduced toward the end portion is formed on the rotating shaft,
Since the discharging means is the tapered portion, at least one of a through hole and a recess formed in the mounting portion so as to communicate with a space formed between the rotating shaft and the mounting portion of the holder. A motor characterized by being configured.

  According to this configuration, the through hole or recess formed in the mounting portion of the holder communicates with the space formed by the tapered portion of the rotating shaft, and the inside of the holder and the outside communicate with each other, so that the air in the holder is discharged. it can. Further, by using the space formed by forming the tapered portion of the rotating shaft, it is possible to contribute to an improvement in the degree of freedom of the position where the through hole or the concave portion formed in the mounting portion of the holder is provided.

(E) In the motor described in (d) above,
The motor is characterized in that the rotating shaft has an R-shaped corner portion that changes from an outer peripheral surface of the rotating shaft to an inclined surface in the tapered portion.

According to this structure, the corner | angular part which changes to the slope from the outer peripheral surface of the rotating shaft in the taper part of a rotating shaft is formed in R shape, and attachment of the holder with respect to a rotating shaft becomes easy.
(F) In the motor described in (a) above,
The discharging means is composed of a through-hole formed in a portion of the holder that holds the sensor magnet, and a recess formed in the sensor magnet so as to connect the through-hole and the inside of the holder. A motor characterized by

  According to this configuration, the through-hole formed in the portion of the holder that holds the sensor magnet is connected to the recess formed in the sensor magnet, and the inside of the holder communicates with the outside, so that the air in the holder can be discharged. . Further, the discharging means can be configured simply.

(G) In the motor described in (a) above,
The motor according to claim 1, wherein the discharging means is formed of a recess formed on an outer peripheral surface of the rotating shaft and communicating the inside and outside of the holder.

According to this structure, the air in a holder can be discharged | emitted through the recessed part which connects the inside of the holder formed in the outer peripheral surface of a rotating shaft, and the exterior. Further, the discharging means can be configured simply.
(H) In the motor described in any one of (i) to (d) above,
The motor according to claim 1, wherein the holder is formed with at least a nonmagnetic material at a mounting portion with the rotating shaft.

  According to this configuration, the holder is formed with at least the nonmagnetic material at the mounting portion with the rotating shaft. Here, depending on the material of the rotating shaft, the magnetic flux generated from the sensor magnet may leak into the rotating shaft, and the magnetic field generated by the sensor magnet may be weakened. When the magnetic field generated by the sensor magnet becomes weak, it becomes difficult for the magnetic sensor to detect the magnetic field, so that an error occurs in the detected rotational position of the rotor, and the rotational performance of the motor controlled based on the rotational position is reduced. In the present invention, the leakage of magnetic flux from the sensor magnet to the rotating shaft can be reduced by increasing the magnetic resistance between the rotating shaft and the sensor magnet formed by a non-magnetic material in the holder mounting portion. Can do.

(L) In the motor according to any one of the above items (i) to (i),
A motor comprising a gap or a magnetoresistive portion made of a nonmagnetic material interposed between the sensor magnet and the end surface of the rotating shaft.

  According to this configuration, a gap or a magnetoresistive portion made of a nonmagnetic material is interposed between the sensor magnet and the end surface of the rotating shaft. Thereby, the leakage of the magnetic flux from a sensor magnet to a rotating shaft can be reduced by providing a magnetoresistive part and raising the magnetic resistance between a sensor magnet and a rotating shaft.

(Nu) In the motor according to any one of (i) to (i) above,
A motor, wherein the sensor magnet and the holder are integrally formed.
According to this configuration, since the sensor magnet and the holder are integrally formed, an increase in the number of components can be suppressed as compared with a configuration in which the sensor magnet and the holder are independent from each other.

(Le) In the motor described above,
The motor is characterized in that the sensor magnet is a plastic magnet and is integrally formed with the holder as a metal member.

  According to this configuration, the sensor magnet formed of the plastic magnet is integrally formed with the holder of the metal member, thereby suppressing an increase in the number of components and improving the holding force with respect to the sensor magnet and the fixing force with the rotating shaft. be able to.

(Wo) In the motor according to any one of the above-described (1) to (2),
A motor characterized by comprising discriminating means for indicating a magnetizing mode of the sensor magnet.

  According to this configuration, since the discriminating means that indicates the magnetizing mode of the sensor magnet is provided, the sensor magnet that needs to be positioned with respect to the rotor can be easily attached at an appropriate position.

  DESCRIPTION OF SYMBOLS 1 ... Motor case (case member), 22c, 32a, 33a, 35d ... Through-hole (discharge means), 11 ... Stator, 21 ... Rotor, 22 ... Rotating shaft, 22a ... End surface, 22b ... Outer peripheral surface, 22e, 32e, 62 ... concave portion (discharge means), 23 ... rotor core, 23b ... pseudo magnetic pole, 24 ... field magnet, 31 ... holder, 32 ... sensor magnet, 33 ... cylindrical portion (mounting portion), 37 ... gap (magnetic resistance portion), 38, 39 ... Magnetized part (magnetic pole part), 44 ... Magnetic sensor, 51, 52 ... Magnetic induction part, 51d, 52d ... End face, 61 ... Adhesive (magnetic resistance part), 65 ... Tapered part (discharge means) , 66 ... space, 67 ... corner, 68a ... flat surface (discriminating means), M ... motor.

Claims (12)

A sensor magnet having a pair of magnetic pole portions fixed to the rotating shaft of the rotor so as to be integrally rotatable;
A magnetic sensor that is disposed opposite to the sensor magnet and detects a change in the magnetic field accompanying the rotation of the sensor magnet,
A motor for rotationally driving the rotor based on detection of a rotational position of the rotor by the magnetic sensor;
A magnetic induction portion made of a magnetic material extending from a pair of different magnetic pole portions of the sensor magnet and facing each other with the magnetic sensor in between ;
The sensor magnet is fixed via a holder fixed to the rotating shaft so as to be integrally rotatable,
The holder has a cylindrical portion, and an end portion of the rotating shaft is press-fitted into the cylindrical portion,
As a discharge means that enables discharge of air in the cylindrical portion of the holder that is closed by mounting the sensor magnet and the rotating shaft, a concave portion is provided on the inner side surface of the cylindrical portion,
Between the outer peripheral surface of the rotating shaft and the inner surface of the cylindrical portion of the holder, a gap is formed by the recess,
The rotating shaft is formed with a tapered portion that decreases in diameter toward the end portion, and by forming the tapered portion, a space is formed between the rotating shaft and the cylindrical portion of the holder,
The said recessed part is provided so that it may connect with the said space formed between the said rotating shaft and the cylinder part of the said holder, and the inside and outside of the cylinder part of the said holder are connected . The motor according to claim 1,
The motor is characterized in that a plurality of the recesses are formed at equal intervals in the circumferential direction on the inner side surface of the cylindrical part. The motor according to claim 1 or 2 ,
The sensor magnet and the magnetic sensor are arranged to face each other in the axial direction of the rotation shaft,
The motor according to claim 1, wherein the magnetic induction portion is configured such that tip surfaces opposed to the magnetic sensor in a radial direction are parallel to each other. The motor according to any one of claims 1 to 3 ,
The motor is characterized in that the rotating shaft has an R-shaped corner portion that changes from an outer peripheral surface of the rotating shaft to an inclined surface in the tapered portion. In the motor according to any one of claims 1 to 4 ,
The motor according to claim 1, wherein the cylindrical portion, which is a mounting portion with the rotating shaft , is formed of at least a nonmagnetic material. The motor according to any one of claims 1 to 5 ,
A motor comprising a gap or a magnetoresistive portion made of a nonmagnetic material interposed between the sensor magnet and the end surface of the rotating shaft. In the motor according to any one of claims 1 to 5 ,
A motor, wherein the sensor magnet and the holder are integrally formed. The motor according to claim 7 , wherein
The motor is characterized in that the sensor magnet is a plastic magnet and is integrally formed with the holder as a metal member. The motor according to any one of claims 1 to 8 ,
A motor characterized by comprising discriminating means for indicating a magnetizing mode of the sensor magnet. The motor according to any one of claims 1 to 9 ,
In the rotor, a plurality of field magnets functioning as one magnetic pole are arranged in the circumferential direction of the rotor core, pseudo magnetic poles integrally formed with the rotor core are arranged between the magnets, and the pseudo magnetic pole is the other magnetic pole. A motor that is configured to function as a motor. The motor according to any one of claims 1 to 10 ,
An annular stator that is radially opposed to the rotor is housed in a case member made of a ferromagnetic material,
The motor, wherein the sensor magnet is fixed to the rotating shaft outside the case member. An electric power steering motor using the structure of the motor according to any one of claims 1 to 11.

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