JP2006353052A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor which shortens the axial dimension by constituting so that a position sensor is arranged close to an armature coil. <P>SOLUTION: A disc type sensor yoke 10, including a plate surface orthogonal to the axis of a rotor 5 is arranged between the rotor body 6 and an axial end of a motor housing 1, and is fixed to a rotating shaft 7 of the rotor 5. A sensor magnet 11 is fitted to the plate surface of the sensor yoke 10 facing an axial end side of the motor housing 1. The sensor yoke 10 has a larger outside diameter than that of the sensor magnet 11, and the outside diameter of the sensor yoke 10 is set so that a portion of the sensor yoke 10, which protrudes outward in the radial direction larger than the sensor magnet 11, constitutes a shielding member which shields the magnetic flux generated by the armature coil 4, from the position sensor 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor including a stator having an armature coil and a rotor having a magnet field.

  As shown in FIG. 4, the brushless motor includes a stator 2 ′ having an armature coil 4 ′, a rotor 5 ′ having a magnet field, and a position detection device 15 ′ that detects a rotational angle position of the rotor 5 ′. And an excitation control circuit that switches the excitation phase of the armature coil so as to rotate the rotor in a predetermined direction in accordance with the position information of the rotor detected by the position detection device.

  In the example shown in FIG. 4, as the position detection device 15 ', a device that detects the magnetic field magnetic pole of the rotor 5' by a position sensor 13 'made of a Hall element or the like and outputs a position detection signal is used. . In this case, the position sensor 13 ′ needs to be installed at a position sufficiently away from the stator 2 ′ so as not to be affected by the magnetic flux generated from the armature coil. Therefore, the normal position sensor 13 'is arranged on one end side in the axial direction of the motor housing 1' as shown in the drawing. In the illustrated example, a printed circuit board 12 'is disposed near one end of the motor housing 1' in the axial direction, and a position sensor 13 'is attached to the printed circuit board together with electronic components (not shown) constituting an excitation control circuit. It has been. In this way, the position sensor 13 'is arranged on one end side in the axial direction of the motor housing 1', and the magnetic field magnetic pole of the rotor 5 'is detected without being affected by the magnetic flux generated from the armature coil 4'. For this purpose, it is necessary to extend the end portion of the rotor 5 'from the end portion of the stator 2' and extend it to a position in the vicinity of the position sensor 13 ', and accordingly, the axial length of the motor housing 1' is increased. There is a need to. Therefore, this type of motor has a problem that the axial lengths of the rotor 5 'and the motor housing 1' become long, and the motor becomes large.

  Therefore, as shown in Patent Document 1 and Patent Document 2, a sensor magnet magnetized to have a magnetic pole arrangement similar to the magnetic pole arrangement of the magnet field of the rotor is attached to the rotating shaft of the rotor, A sensor in which a position detection signal is obtained by detecting a magnetic pole of a sensor magnet with a position sensor is used.

However, even when the sensor magnet is provided as described above, if the position sensor is close to the armature coil, a noise signal is generated in response to the magnetic flux generated from the armature coil. It is necessary to arrange it some distance away.
JP 2000-69784 A JP 2004-304945 A

  As described above, in the conventional brushless motor, the position sensor needs to be arranged away from the armature coil in order to prevent the position sensor from being affected by the magnetic flux generated from the armature coil. It was inevitable that the axial dimension of the housing would become longer and the motor would become larger.

  An object of the present invention is to make it possible to obtain a detection signal including information on the rotational angle position of a rotor without being affected by the magnetic flux generated from the armature coil even if the position sensor is disposed close to the armature coil. Thus, an object of the present invention is to provide a brushless motor capable of reducing the axial dimension.

  The present invention relates to a stator in which an armature coil is wound around an annular stator iron core fixed to the inner periphery of a motor housing, a rotor body having a magnet field and disposed inside the stator, and a rotating shaft. The rotor shaft is rotatably supported at both ends in the axial direction of the motor housing, and one end side in the axial direction of the motor housing is magnetized so as to have a plurality of magnetic poles aligned in the circumferential direction of the rotor And a position sensor for detecting a magnetic pole of the sensor magnet inside one end in the axial direction of the motor housing and outputting a position detection signal including information on the rotational angle position of the rotor And an excitation control circuit that switches the excitation phase of the armature coil in accordance with the position detection signal in order to rotate the rotor.

  In a preferred aspect of the present invention, a disk-shaped sensor yoke having a plate surface perpendicular to the axis of the rotor is disposed between the rotor body and one end in the axial direction of the motor housing, and is fixed to the rotating shaft of the rotor. A sensor magnet is attached to the plate surface of the sensor yoke facing one end side in the axial direction of the housing. The sensor yoke has an outer diameter that is larger than the outer diameter of the sensor magnet, and the portion of the sensor yoke that protrudes outward in the radial direction from the sensor magnet generates magnetic flux generated from the armature coil of the stator from the position sensor. The outer diameter of the sensor yoke is set so as to constitute a shielding member for shielding.

  With the above configuration, since the sensor yoke shields the position sensor from the magnetic flux generated by the armature coil, even if the sensor yoke, the sensor magnet, and the position sensor are arranged close to the armature coil, the armature coil A position detection signal including information on the rotational angle position of the rotor can be obtained without being affected by the generated magnetic flux. Therefore, the sensor yoke, the sensor magnet, and the position sensor can be brought close to the armature coil to reduce the axial dimension of the motor, and the brushless motor can be reduced in size.

  In another preferred aspect of the present invention, the sensor yoke formed in a cup shape has its opening directed toward one end side in the axial direction of the motor housing, and the axis of the rotor main body and the motor housing is shared with the rotor. It arrange | positions between the one ends of a direction, is fixed to the rotating shaft of a rotor, and a sensor magnet is attached inside the bottom wall part of this cup-shaped sensor yoke. In this case, the position sensor is disposed inside the cup-shaped sensor yoke and fixed to the motor housing, and the position sensor is shielded from the magnetic flux generated from the armature coil of the stator by the sensor yoke.

  Even in such a configuration, the sensor yoke, the sensor magnet, and the position sensor can be disposed close to the armature coil, so that the axial dimension of the motor can be reduced.

  According to the present invention, since the sensor yoke shields the position sensor from the magnetic flux generated by the armature coil, the sensor yoke, the sensor magnet, and the position sensor are arranged close to the armature coil, and the axial direction of the motor The dimensions can be reduced, and the size of the brushless motor can be reduced.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a housing body 1a formed in a cylindrical shape and an end cover 1b attached so as to close the open end of the housing body 1a. This is a motor housing.

  Reference numeral 2 denotes a stator. The stator includes an annular stator core 3 fixed to the inner periphery of the main body 1 a of the motor housing 1, and a multiphase (for example, three-phase) armature wound around a slot of the stator core 3. It consists of a coil 4.

  Reference numeral 5 denotes a rotor. This rotor is provided in a state in which a permanent magnet is attached to a rotor yoke made of a laminate of steel plates to form a magnet field, and a shaft portion of the rotor body is penetrated. It is comprised with the rotating shaft 7. FIG. The rotor body 6 is arranged inside the stator in a state of sharing the axis with the stator 2, and one end and the other end of the rotating shaft 7 are end walls on one end side in the axial direction of the motor housing 1 (this example) Then, the end cover 1b) and the end wall on the other end side are supported via bearings 8 and 9, respectively.

  Reference numeral 10 denotes a sensor yoke formed in a disk shape from a ferromagnetic material such as iron. The sensor yoke has an axial direction of the rotor body 6 and the motor housing 1 in a state where the plate surface is orthogonal to the axis of the rotor 5. Between the two ends (end cover 1 b) of the rotor 5 and fixed to the rotating shaft 7 of the rotor 5. The illustrated sensor yoke has a boss portion 10 a at the center thereof, and the boss portion 10 a is fixed to the rotation shaft 7 by being fitted to the rotation shaft 7.

  A sensor magnet 11 is attached to the sensor yoke 10. As shown in FIG. 2, the sensor magnet 11 has a thickness direction such that the same number of magnetic poles (4 in the illustrated example) as the magnetic field of the rotor 5 is aligned in the circumferential direction with the same arrangement as the magnetic poles of the rotor 5. The sensor yoke 10 is attached to the plate surface of the sensor yoke 10 facing the one end side in the axial direction of the motor housing 1.

  A printed circuit board 12 disposed so as to face the sensor yoke 10 is fixed inside one end (end cover) of the motor housing 1 in the axial direction, and a position sensor 13 is attached to the printed circuit board 12. The position sensor 13 is composed of a magnetic sensor such as a Hall IC. The position sensor 13 detects the magnetic pole of the sensor magnet 11 and outputs an electrical signal indicating different levels depending on whether the detected magnetic pole is an N pole or an S pole. Is output as a position detection signal including information on the rotation angle position.

  The sensor yoke 10 has an outer diameter larger than the outer diameter of the sensor magnet 11, and a portion 10 b of the sensor yoke 10 that protrudes outward in the radial direction from the sensor magnet 11 is formed from the armature coil 4 of the stator. The outer diameter dimension of the sensor yoke 10 is set so as to constitute a shielding member that shields the generated magnetic flux from the position sensor 13. In this example, the sensor yoke 10, the sensor magnet 11, and the position sensor 13 constitute a position detection device 15 that outputs a position detection signal including information on the rotational angle position of the rotor 5.

  The printed circuit board 12 is also mounted with electronic components that constitute an excitation control circuit that switches the excitation phase of the armature coil 4 in accordance with a position detection signal output from the position sensor 13, and the excitation control circuit rotates the rotor 5. By switching the excitation phase of the armature coil 4 according to the angular position, a rotating magnetic field is generated to rotate the rotor 5 in a predetermined direction.

  If comprised as mentioned above, since the sensor yoke 10 shields the position sensor 13 from the magnetic flux which an armature coil generate | occur | produces, the sensor yoke 10, the sensor magnet 11, and the position sensor 13 are arrange | positioned close to the armature coil 4. However, a position detection signal including information on the rotational angle position of the rotor 5 can be obtained without being affected by the magnetic flux generated by the armature coil 4. Therefore, the sensor yoke 10, the sensor magnet 11, and the position sensor 13 can be brought close to the armature coil 4 to reduce the axial dimension of the motor, and the brushless motor can be reduced in size.

  FIG. 3 shows another embodiment of the present invention. In this example, the cup has a peripheral wall portion 20a and a bottom wall portion 20b provided to close one end of the peripheral wall portion in the axial direction. The sensor yoke 20 formed in the above is used. The sensor yoke 20 is made of a ferromagnetic material such as iron, and its opening is directed to one end side (end cover side) in the axial direction of the motor housing 1 and the axis is shared with the rotor 5. It is disposed between the rotor body 6 and one end of the motor housing 1 in the axial direction and is fixed to the rotating shaft 7 of the rotor 5.

  The sensor magnet 11 is made of an annular permanent magnet that is magnetized in the same manner as the example shown in FIG. 1, and is attached to the inside of the bottom wall portion 20 b of the cup-shaped sensor yoke 20. In this example, the printed circuit board 12 is formed in a disk shape having an outer diameter smaller than the inner diameter of the peripheral wall portion 20 a of the sensor yoke 20, and the printed circuit board 12 is disposed inside the sensor yoke 20. . Therefore, a gap is formed between the inner periphery of the peripheral wall portion 20 a of the sensor yoke 20 and the outer periphery of the printed circuit board 12, and the sensor yoke 20 rotates together with the rotor 5 without being blocked by the printed circuit board 12. The position sensor 13 is attached to the printed circuit board 12 and disposed inside the sensor yoke 20 together with the printed circuit board. The position sensor 13 is shielded from the magnetic flux generated from the armature coil 4 of the stator by the sensor yoke 20. The position detection device 15 is configured by the sensor yoke 20, the sensor magnet 11, and the position sensor 13. The other points are configured in the same manner as the embodiment shown in FIG.

  Even when configured as shown in FIG. 3, the sensor yoke 20 shields the position sensor 13 from the magnetic flux generated by the armature coil 4, so that the sensor yoke 20, the sensor magnet 11, and the position sensor 13 are armature coil. Even if it is arranged close to 4, a position detection signal including information on the rotational angle position of the rotor 5 can be obtained without being affected by the magnetic flux generated by the armature coil 4.

  In FIG. 1 and FIG. 3, only one position sensor 13 is shown. However, when the armature coil 4 is configured in multiple phases, a plurality of normal position sensors 13 are provided. For example, when the armature coil is composed of a three-phase coil, three position sensors 13 are provided.

It is the longitudinal cross-sectional view which showed the structure of embodiment of this invention. It is the front view which showed the sensor yoke and sensor magnet which are used in embodiment of FIG. It is the longitudinal cross-sectional view which showed other embodiment of this invention. It is the longitudinal cross-sectional view which showed the structure of the conventional brushless motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor housing 2 Stator 3 Stator iron core 4 Armature coil 5 Rotor 6 Rotor main body 7 Rotating shaft 10, 20 Sensor yoke 11 Sensor magnet 13 Position sensor

Claims (2)

A stator formed by winding an armature coil around an annular stator core fixed to the inner periphery of a motor housing; a rotor body having a magnet field and disposed inside the stator; and a rotating shaft The rotating shaft is magnetized so as to have a rotor rotatably supported at both ends in the axial direction of the motor housing, and a plurality of magnetic poles arranged in the circumferential direction of the rotor, and at one end side in the axial direction of the motor housing. A sensor magnet fixed to the rotation shaft of the rotor, and a position detection signal including information on the rotation angle position of the rotor by detecting the magnetic pole of the sensor magnet inside one end of the motor housing in the axial direction A brushless motor comprising: a position sensor configured to rotate; and an excitation control circuit that switches an excitation phase of the armature coil in accordance with the position detection signal to rotate the rotor. Stomach,
A disk-shaped sensor yoke having a plate surface perpendicular to the axis of the rotor is disposed between the rotor body and one end in the axial direction of the motor housing and fixed to the rotation shaft of the rotor,
The sensor magnet is attached to the plate surface of the sensor yoke facing the one end side in the axial direction of the motor housing,
The sensor yoke has an outer diameter larger than the outer diameter of the sensor magnet, and a portion of the sensor yoke that protrudes radially outward from the sensor magnet is generated from the armature coil of the stator. A brushless motor, wherein the outer diameter of the sensor yoke is set so as to constitute a shielding member that shields magnetic flux from the position sensor. A stator formed by winding an armature coil around an annular stator core fixed to the inner periphery of a motor housing; a rotor body having a magnet field and disposed inside the stator; and a rotating shaft The rotating shaft is magnetized so as to have a rotor rotatably supported at both ends in the axial direction of the motor housing, and a plurality of magnetic poles arranged in the circumferential direction of the rotor, and at one end side in the axial direction of the motor housing. A sensor magnet fixed to the rotation shaft of the rotor, and a position detection signal including information on the rotation angle position of the rotor by detecting the magnetic pole of the sensor magnet inside one end of the motor housing in the axial direction A brushless motor comprising: a position sensor configured to rotate; and an excitation control circuit that switches an excitation phase of the armature coil in accordance with the position detection signal to rotate the rotor. Stomach,
A sensor yoke formed in a cup shape has its opening directed toward one end side in the axial direction of the motor housing and between the rotor body and one end in the axial direction of the motor housing in a state of sharing the axis with the rotor. Is fixed to the rotating shaft of the rotor,
The sensor magnet is attached to the inside of the bottom wall of the cup-shaped sensor yoke,
The position sensor is disposed inside the cup-shaped sensor yoke and fixed to the motor housing,
The position sensor is shielded from the magnetic flux generated from the armature coil of the stator by the sensor yoke;
Brushless motor characterized by

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