JP2014099955A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor that can make it hard for a field magnet to be demagnetized (irreversible temperature change) even if the temperature gets high inside a vehicle engine room.SOLUTION: A brushless motor 11 for a valve timing variable device 3 comprises a rotor of which first unguiform magnetic poles 31b function as first magnetic poles and second unguiform magnetic poles function as second magnetic poles by placing an annular magnet 33 magnetized in an axial direction between axial directions of a first rotor core 31 in which the multiple first unguiform magnetic poles 31b are formed in a circumferential direction and a second rotor core 32 in which the multiple second unguiform magnetic poles are formed in a circumferential direction.

Description

  The present invention relates to a brushless motor for a position control device disposed in a vehicle engine room.

  Conventionally, as a motor for a position control device arranged in a vehicle engine room, for example, there is a brushless motor for a valve timing variable device disclosed in Patent Document 1. This brushless motor includes a rotor in which a field magnet is inserted and fixed in a hole penetrating in the axial direction of the rotor core.

Japanese Patent No. 4468033

  However, in the brushless motor as described above, the field magnet is easily affected by the outside due to the configuration in which the field magnet is inserted and fixed in the hole penetrating in the axial direction of the rotor core. Then, there is a problem that the field magnet is easily demagnetized (irreversible temperature change). In addition, since the magnetic force of the field magnet becomes weak in a high temperature state, it may be possible to control to increase the current flowing through the stator coil. However, in this case, the field magnet is more demagnetized (irreversible temperature change). ).

  The present invention has been made to solve the above-described problems, and an object thereof is to make it difficult to demagnetize a field magnet (irreversible temperature change) even if, for example, the temperature in a vehicle engine room becomes high. The object is to provide a brushless motor capable of achieving the above.

  A brushless motor that solves the above-described problem is a brushless motor for a position control device that is disposed in a vehicle engine room, and includes a first rotor core having a plurality of first magnetic pole portions formed in the circumferential direction and a plurality of circumferentially arranged plurality of first magnetic pole portions. The field magnet magnetized in the axial direction is disposed between the second rotor core in which the second magnetic pole portion is formed, so that the first magnetic pole portion functions as a first magnetic pole, The second magnetic pole part includes a rotor that functions as a second magnetic pole.

  According to this configuration, the field magnet of the rotor in the brushless motor for the position control device disposed in the vehicle engine room is disposed between the first rotor core and the second rotor core in the axial direction, and is affected by external influences. For example, it is difficult to demagnetize the field magnet (irreversible temperature change) even if the temperature in the vehicle engine room becomes high. Therefore, position control can be performed stably.

  In the brushless motor, the first magnetic pole portion and the second magnetic pole portion protrude radially outward from the outer peripheral portions of the substantially disk-shaped first and second core bases of the first and second rotor cores, and It is preferable that the first claw-shaped magnetic pole and the second claw-shaped magnetic pole extend in the axial direction so as to cover the radially outer surface of the field magnet.

  According to the same configuration, the first magnetic pole part and the second magnetic pole part protrude outward in the radial direction from the outer peripheral parts of the first and second core bases of the substantially disk shape of the first and second rotor cores. Since the first claw-shaped magnetic pole and the second claw-shaped magnetic pole extend in the axial direction so as to cover the radially outer surface of the field magnet, the field magnet is less susceptible to external influences. Therefore, for example, even if the temperature in the vehicle engine room becomes high, the field magnet can be made more difficult to demagnetize (irreversible temperature change).

  In the brushless motor, the field magnet may be set so as to be disposed radially inward from the outer peripheral portions of the first and second core bases having substantially disk shapes of the first and second rotor cores. preferable.

  According to this configuration, the field magnet is set so as to be disposed radially inward from the outer peripheral portions of the disk-shaped first and second core bases of the first and second rotor cores. It becomes difficult to be affected by. Therefore, for example, even if the temperature in the vehicle engine room becomes high, the field magnet can be made more difficult to demagnetize (irreversible temperature change).

In the brushless motor, the first rotor core and the second rotor core are preferably fastened and fixed by a fastening member.
According to this configuration, since the first rotor core and the second rotor core are fastened and fixed by the fastening member, for example, the first rotor core and the second rotor core are firmly fixed as compared with those fixed using an adhesive, and the interior of the vehicle engine room is hot. Even if it becomes, the adhesion part does not peel.

In the brushless motor, it is preferable that the number of poles of the rotor is set to 2 × n (where n is a natural number), and the number of concentrated winding teeth of the stator is set to 3 × n.
According to this configuration, the number of poles of the rotor is set to 2 × n (where n is a natural number), and the number of concentrated winding teeth of the stator is set to 3 × n. The portion and the concentrated winding teeth can face each other, and the detent torque can be increased. Therefore, it is possible to prevent the rotor from rotating due to vibrations in the vehicle engine room when not driven.

  In the brushless motor, it is preferable that the cross-sectional shape of the first magnetic pole portion and the second magnetic pole portion in the direction perpendicular to the axis of the radially outer surface is not a concentric circle centering on the central axis of the rotation shaft of the rotor.

  According to this configuration, the cross-sectional shape in the direction perpendicular to the axis of the radially outer surface of the first magnetic pole part and the second magnetic pole part does not become a concentric circle centering on the central axis of the rotation axis of the rotor. The intervals between the surfaces of the first and second magnetic pole portions and the stator will vary. Therefore, a large change in the magnetic field is caused by the fluctuation, resulting in a load during rotation, and the detent torque increases. Therefore, it is possible to prevent the rotor from rotating due to vibrations in the vehicle engine room when not driven.

The brushless motor is preferably for a valve timing variable device.
According to this configuration, the durability of the brushless motor for the variable valve timing device can be increased, and the valve timing can be changed stably.

  In the brushless motor of the present invention, for example, the field magnet can be made difficult to demagnetize (irreversible temperature change) even if the temperature in the vehicle engine room becomes high.

Sectional drawing of the brushless motor in one Embodiment. The partial cross section perspective view of the brushless motor in the same form. (A) is a perspective view of a rotor in another example. (B) is sectional drawing of the rotor in another example. (A) is a perspective view of a rotor in another example. (B) is sectional drawing of the rotor in another example. (A) is a perspective view of a rotor in another example. (B) is sectional drawing of the rotor in another example. The perspective view of the rotor in another example. Sectional drawing of the rotor in another example.

Hereinafter, an embodiment of a brushless motor will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the brushless motor 11 of this embodiment is for a position control device disposed in a vehicle engine room 1, specifically for a valve timing variable device 3 connected to an engine 2.

  As shown in FIG. 1, a motor case 12 of a brushless motor 11 has a cylindrical housing 13 formed in a bottomed cylindrical shape and a front side (left side in FIG. 1) opening of the cylindrical housing 13 closed. And a front end plate 14.

  As shown in FIG. 1, a stator 16 is fixed to the inner peripheral surface of the cylindrical housing 13. The stator 16 is wound around an armature core 17 having a plurality of (in this embodiment, 12) teeth 17a serving as concentrated winding teeth extending radially inward and a tooth 17a of the armature core 17 via an insulator 18. Winding 19 is provided. The stator 16 generates a rotating magnetic field when a drive current is supplied from the external control circuit S to the winding 19.

  As shown in FIG. 1, the rotor 21 of the brushless motor 11 has a rotating shaft 22 and is disposed inside the stator 16. The rotating shaft 22 is a non-magnetic metal shaft, and is rotatably supported by bearings 23 and 24 supported by the bottom portion 13a of the cylindrical housing 13 and the front end plate 14. The valve timing variable device 3 is connected to the tip of the rotating shaft 22 protruding to the outside, and the valve timing according to the operating state by the rotational driving of the rotating shaft 22 (the relative rotational phase of the camshaft with respect to the crankshaft of the engine 2). Are appropriately changed.

As shown in FIGS. 1 and 2, the rotor 21 includes first and second rotor cores 31 and 32 that are fitted onto the rotary shaft 22, and an annular magnet 33 as a field magnet.
The first rotor core 31 has a plurality of first claw-shaped magnetic poles 31b as radial first outer peripheral portions on the outer periphery of a substantially disc-shaped first core base 31a at equal intervals (four in this embodiment). And extending in the axial direction.

  The second rotor core 32 has the same shape as the first rotor core 31, and second claw-shaped magnetic poles 32 b as a plurality of second magnetic pole portions are arranged at equal intervals on the outer peripheral portion of the substantially disk-shaped second core base 32 a. It protrudes radially outward and extends in the axial direction. The second rotor core 32 is arranged such that each second claw-shaped magnetic pole 32b is disposed between the first claw-shaped magnetic poles 31b adjacent to each other in the circumferential direction, and between the first core base 31a and the second core base 32a. The annular magnet 33 is assembled to the first rotor core 31 so as to be disposed (clamped) in the axial direction. In the present embodiment, the first and second core bases 31a and 32a are respectively fixed to the annular magnet 33 with an adhesive.

  As shown in FIG. 1, the annular magnet 33 is a neodymium magnet, and more specifically, the outer diameter thereof is disposed radially inward from the outer peripheral portions of the first and second core bases 31 a and 32 a. Is set smaller than the outer diameter of the first and second core bases 31a and 32a. The annular magnet 33 causes the first claw-shaped magnetic pole 31b to function as the first magnetic pole (N pole in the present embodiment), and the second claw-shaped magnetic pole 32b serves as the second magnetic pole (S pole in the present embodiment). It is magnetized in the axial direction to function. That is, the rotor 21 of the present embodiment is a so-called Landell type rotor using an annular magnet 33 as a field magnet. In the rotor 21, first claw-shaped magnetic poles 31b that are N poles and second claw-shaped magnetic poles 32b that are S poles are alternately arranged in the circumferential direction, and the number of poles is 8 (the number of pole pairs is 4). It becomes. That is, in the present embodiment, the number of poles of the rotor 21 is set to 2 × n (where n is a natural number), and the number of teeth 17a of the stator 16 is set to 3 × n. The number of poles 21 is set to “8”, and the number of teeth 17a of the stator 16 is set to “12”.

  In the present embodiment, the assembled first and second core bases 31a and 32a and the annular magnet 33 are set to have a diameter that is at least four times the axial length, and the diameter is specifically 100 mm or less. Is set to

  As shown in FIG. 1, the rotor 21 of the present embodiment is provided with a sensor magnet 42 via a substantially disk-shaped magnet fixing member 41. The magnet fixing member 41 is fitted on the rotary shaft 22 on the opposite side of the first rotor core 31 from the second rotor core 32, and the sensor magnet 42 is fixed on the outer peripheral side thereof. The sensor magnet 42 is configured such that N poles and S poles appear alternately at predetermined angles in the circumferential direction (rotation direction). In the front end plate 14, a hall element 43 is provided at a position facing the sensor magnet 42 in the axial direction, and the rotational position of the rotor 21 can be detected by detecting the sensor magnet 42 with the hall element 43. Has been.

Next, the operation of the brushless motor 11 configured as described above will be described.
For example, when control is performed to change the valve timing in accordance with the driving state during vehicle travel, a three-phase drive current is supplied from the control circuit S to the winding 19 to generate a rotating magnetic field. Then, the rotor 21 is driven to rotate, and the valve timing (the relative rotation phase of the camshaft with respect to the crankshaft of the engine 2) is changed by the valve timing variable device 3.

Next, the characteristic effects of the above embodiment will be described below.
(1) The annular magnet 33 of the rotor 21 in the brushless motor 11 for the variable valve timing device 3 disposed in the vehicle engine room 1 is disposed between the first rotor core 31 and the second rotor core 32 in the axial direction. . Thereby, since the annular magnet 33 becomes difficult to receive the influence of the outside, for example, even if the inside of the vehicle engine room 1 becomes high temperature, it is difficult to demagnetize the annular magnet 33 (irreversible temperature change). Therefore, the position control, that is, the valve timing can be changed stably.

  (2) The first magnetic pole part and the second magnetic pole part protrude outward in the radial direction from the outer peripheral parts of the substantially disk-shaped first and second core bases 31a and 32a of the first and second rotor cores 31 and 32. In addition, since the first and second claw-shaped magnetic poles 31b and 32b extend in the axial direction so as to cover the radially outer surface of the annular magnet 33, the annular magnet 33 is less susceptible to external influences. Therefore, for example, even if the inside of the vehicle engine room 1 becomes high temperature, the annular magnet 33 can be made more difficult to demagnetize (irreversible temperature change).

  (3) The annular magnet 33 is set so as to be disposed radially inward from the outer peripheral portions of the disk-shaped first and second core bases 31 a and 32 a of the first and second rotor cores 31 and 32. , Less susceptible to external influences. Therefore, for example, even if the inside of the vehicle engine room 1 becomes high temperature, the annular magnet 33 can be made more difficult to demagnetize (irreversible temperature change).

  (4) Since the number of poles of the rotor 21 is set to 2 × n (where n is a natural number) and the number of teeth 17a of the stator 16 is set to 3 × n, the least common multiple is reduced, and the first And many 2nd nail | claw-shaped magnetic poles 31b and 32b and the teeth 17a can be correctly opposed, and a detent torque can be enlarged. Therefore, it is possible to prevent the rotor 21 from rotating due to vibrations in the vehicle engine room 1 when not driven.

The above embodiment may be modified as follows.
In the above embodiment, the annular magnet 33 is set to be arranged radially inward from the outer peripheral portions of the disk-shaped first and second core bases 31a and 32a of the first and second rotor cores 31 and 32. However, it may be changed.

  For example, as shown in FIGS. 3A and 3B, the outer diameter of the annular magnet 51 may be set to be the same as the outer diameters of the first and second core bases 31a and 32a. In this example (see FIG. 3), the thickness of each member is also changed.

-Although the rotor 21 of the said embodiment provided the permanent magnet only with the annular magnet 33, it is not limited to this, You may change to the rotor which added the other permanent magnet.
For example, as shown in FIGS. 4 (a) and 4 (b), the first and second claw-shaped magnetic poles 31b and 32b in the other example (see FIG. 3) are radially magnetized on the back surfaces (the inner surfaces in the radial direction). The back auxiliary magnet 52 may be added, or the interpole auxiliary magnet 53 magnetized in the circumferential direction may be added between the circumferential directions of the first claw-shaped magnetic pole 31b and the second claw-shaped magnetic pole 32b. Good.

In the above embodiment, the first magnetic pole part and the second magnetic pole part are the first and second claw-shaped magnetic poles 31b and 32b. However, the present invention is not limited to this, and the magnetic pole part may be changed to another shape.
For example, as shown in FIGS. 5A and 5B, the first and second protrusions projecting radially outward from the outer peripheral portions of the first and second core bases 31a and 32a (and not extending in the axial direction). The protruding magnetic poles 31c and 32c may be used.

  The cross-sectional shape in the axis orthogonal direction of the radially outer surface of the first and second claw-shaped magnetic poles 31b and 32b (first magnetic pole part and second magnetic pole part) of the above embodiment is the central axis of the rotary shaft 22 of the rotor 21 You may set so that it may not become a concentric circle centering on.

  For example, as shown in FIG. In this example, the radially outer surfaces of the first and second claw-shaped magnetic poles 31b and 32b have concentric circular arc surfaces centering on the central axis of the rotating shaft 22, and a pair of recesses provided from the circular arc surfaces. The auxiliary groove 55 is provided. In addition, in this example, although it was set as the shape which had the auxiliary groove 55, it is not limited to this, For example, you may form so that the whole radial direction outer surface may not become a concentric circle.

  If it does in this way, the space | interval of the surface of the 1st and 2nd claw-shaped magnetic poles 31b and 32b which are going to rotate and the stator 16 (tooth 17a) will each change. Therefore, a large change in the magnetic field is caused by the fluctuation, resulting in a load during rotation, and the detent torque increases. Therefore, it is possible to prevent the rotor 21 from rotating due to vibrations in the vehicle engine room 1 when not driven.

  In the above embodiment, the first and second core bases 31a and 32a are each fixed and assembled to the annular magnet 33 with an adhesive. However, the present invention is not limited to this and may be assembled in other configurations. .

  For example, as shown in FIG. 7, the first rotor core 31 and the second rotor core 32 may be fastened and fixed by rivets 56 as fastening members. Specifically, in this example, the first and second rotor cores 31 and 32, the annular magnet 51, the rotor case 25 that accommodates them, and the magnet fixing member 41 are formed with a plurality of through holes 57 at positions overlapping in the axial direction. Has been. The through holes 57 in this example are formed at predetermined intervals (90 ° intervals in the circumferential direction in this embodiment) on a concentric circle with the rotation shaft 22 as the center. Then, the first and second rotor cores 31 and 32, the annular magnet 51, the rotor case 25 that accommodates these, the magnet fixing member, and the end portion of the rivet 56 are caulked while the rivet 56 is inserted into the through hole 57. 41 may be caulked (fastened) and fixed. The rotor case 25 of this example includes a bottomed cylindrical housing 25a and a lid portion 25b that closes the opening of the bottomed cylindrical housing 25a. Of course, the rotor case 25 may not be provided. The rivet 56 in this example is made of a nonmagnetic material. The rivet 56 may be changed to other fastening members such as bolts and nuts.

If it does in this way, it will be fixed firmly compared with what was fixed using adhesives, for example, and even if the inside of vehicle engine room 1 becomes high temperature, an adhesion part will not exfoliate.
In the above embodiment, the number of poles of the rotor 21 is set to “8” and the number of teeth 17a of the stator 16 is set to “12”. However, the number may be changed. For example, the number of poles of the rotor 21 may be set to “4”, and the number of teeth 17a of the stator 16 may be set to “6”. Further, for example, the number of poles of the rotor 21 may be set to “6”, and the number of teeth 17a of the stator 16 may be set to “9”. The number of poles of the rotor 21 may be changed to 2 × n (where n is a natural number) and the number of teeth 17a of the stator 16 does not satisfy the condition of 3 × n.

  In the above embodiment, the brushless motor 11 for the valve timing variable device 3 is embodied. However, the brushless motor for another position control device (for example, a throttle valve control device) disposed in the vehicle engine room 1 is embodied. May be.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle engine room, 3 ... Valve timing variable apparatus, 16 ... Stator, 21 ... Rotor, 22 ... Rotary shaft, 31 ... 1st rotor core, 31a ... 1st core base, 31b ... 1st claw-shaped magnetic pole (1st magnetic pole) Part), 31c ... first protruding magnetic pole (first magnetic pole part), 32 ... second rotor core, 32a ... second core base, 32b ... second claw-shaped magnetic pole (second magnetic pole part), 32c ... second protruding magnetic pole ( 2nd magnetic pole part), 33, 51 ... annular magnet (field magnet), 56 ... rivet (fastening member).

Claims (7)

A brushless motor for a position control device disposed in a vehicle engine room,
A field magnet magnetized in the axial direction between the first rotor core formed with a plurality of first magnetic pole portions in the circumferential direction and the second rotor core formed with a plurality of second magnetic pole portions in the circumferential direction. Is provided, the brushless motor includes a rotor in which the first magnetic pole portion functions as a first magnetic pole and the second magnetic pole portion functions as a second magnetic pole. The brushless motor according to claim 1,
The first magnetic pole portion and the second magnetic pole portion protrude radially outward from the outer peripheral portions of the first and second core bases of the first and second rotor cores, and the diameter of the field magnet. A brushless motor comprising a first claw-shaped magnetic pole and a second claw-shaped magnetic pole extending in the axial direction so as to cover the outer side surface in the direction. The brushless motor according to claim 1 or 2,
The brushless motor, wherein the field magnet is set to be arranged radially inward from the outer peripheral portions of the first and second core bases of the first and second rotor cores that are substantially disk-shaped. . The brushless motor according to any one of claims 1 to 3,
The brushless motor, wherein the first rotor core and the second rotor core are fastened and fixed by a fastening member. The brushless motor according to any one of claims 1 to 4,
A brushless motor, wherein the number of poles of the rotor is set to 2 × n (where n is a natural number), and the number of concentrated winding teeth of the stator is set to 3 × n. The brushless motor according to any one of claims 1 to 5,
A brushless motor characterized in that a cross-sectional shape of the first magnetic pole part and the second magnetic pole part in the axially orthogonal direction of the radially outer surface is not a concentric circle centering on the central axis of the rotation axis of the rotor. The brushless motor according to any one of claims 1 to 6,
A brushless motor characterized by being used for a valve timing variable device.