JP2007124885A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor in which lower price and reduction in size can be achieved. <P>SOLUTION: There are disposed magnets 12, in which a pair of the same poles are opposed to each other in an inner peripheral surface of a cylindrical yoke 3 incorporating a rotor 4 therein, and no magnets are disposed in the other pole portions that have opposite poles to the magnets between these magnets and made empty, and the other pole portions are configured as the other pole component 3a by a yoke. Since the number of magnets can be reduced, the cost as a whole can be lowered, even if unit price becomes higher, by using rare-earth magnet for example so that magnetic properties may not be worsened. In particular, the outline of the portion where no magnet of the yoke is deteriorated (parts to serve as other pole portion) can be made thinner than the portion, where magnets are disposed, thus achieving reduction in size. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor having a rotor wound with a coil, a cylindrical yoke that coaxially houses the rotor, and a magnet disposed on an inner peripheral surface of the yoke.

2. Description of the Related Art Conventionally, for example, an inner rotor type motor has a plurality of magnets arranged on the inner peripheral surface of a cylindrical yoke in the circumferential direction so that magnetic poles are alternately arranged (see, for example, Patent Document 1).
JP 2003-324868 A

  In the motor having the above-described conventional structure, a magnet having the same arc-shaped cross-sectional shape is arranged on the entire circumference that surrounds the rotor (armature). For this purpose, a cylindrical yoke is used as described above. Yes. Therefore, the outer shape of the motor having such a structure depends on the outer shape of the cylindrical yoke.

  On the other hand, power window motors, wiper motors, slide door motors, and the like that are mounted on automobiles are required to be miniaturized due to the layout of the vehicle body. For example, in the case of a power window motor, the motor is arranged so that the rotor shaft is along the surface of the door (body), and the output shaft connected to the window opening / closing link mechanism is oriented perpendicular to the rotor shaft. By providing it, the door is made compact in the thickness direction. A gear box is provided between the rotor shaft and the output shaft, and the gear box is integrated with the motor.

  Although the overall length of the motor (axial length) with respect to the axial direction of the rotor can be reduced by the above structure, the shape of the yoke that affects the diameter of the motor is cylindrical. It is not made compact in the extending direction of the output shaft, which is the thickness direction. Further downsizing is important in automobile-mounted equipment, and downsizing of the motor has been required in the extending direction of the output shaft.

  For example, by using a rare-earth magnet as the magnet, it has higher magnetic characteristics than a ferrite magnet, so that it can be expected to be thin when the same magnetic force is obtained. However, the effect of downsizing in the radial direction by reducing the thickness of the magnet is not so great. Rather, there is a problem that the cost increases due to the rare earth element.

  In order to solve such a problem and realize a motor that is inexpensive and can be reduced in size, in the present invention, a rotor wound with a coil and a cylindrical shape that coaxially houses the rotor. A motor having a yoke and a magnet disposed on an inner peripheral surface of the yoke, wherein the magnet includes a pair of magnets disposed so that the same poles face each other, and the pair of the yokes The part between the magnets is formed so as to have a surface having substantially the same diameter as the inner peripheral surface of the magnet so as to be a magnetic pole opposite to the magnetic pole of the magnet.

  In particular, the outer shape of the yoke is preferably formed such that a portion between the pair of magnets is closer to the axis of the yoke than a portion where the pair of magnets are disposed. Further, it is preferable that a magnetic body is disposed on an inner peripheral surface of a portion between the pair of magnets of the yoke.

  The gap between the pair of magnets and the rotor, and the gap between the pair of magnets of the yoke and the rotor may be substantially the same. Further, the circumferential lengths corresponding to the rotation direction of the rotor of the pair of magnets and the portion of the yoke between the pair of magnets may be substantially the same. The pair of magnets may be a rare earth magnet, or the pair of magnets may be a La-Co substituted ferrite magnet. The pair of magnets may have a specific holding force of 300 kA / m or more, or the pair of magnets may be made of a magnet material that can have a specific holding force of 300 kA / m or more. The motor may be a 4-pole motor.

  Further, an output shaft for transmitting the rotational force of the rotor to an external load is provided in a direction intersecting with the shaft of the rotor, and the output shaft extends between the pair of magnets of the yoke in the extending direction of the output shaft. It is good to arrange so as to match the part.

  As described above, according to the present invention, a pair of magnets with the same polarity facing each other is disposed on the inner peripheral surface of the cylindrical yoke incorporating the rotor, and the magnets are disposed between the magnets. It is possible to reduce the number of magnets by forming a portion that is substantially the same surface as the inner peripheral surface of the magnet and forming a magnetic pole opposite to the magnetic pole by the magnet. By using, for example, a La—Co substituted ferrite magnet or a rare earth magnet so as not to deteriorate the magnetic characteristics, the cost can be reduced as a whole even if the unit price is increased. In particular, the intrinsic holding force of the magnet is preferably 300 kA / m or more.

  In particular, since the outer shape of the portion of the yoke where the magnet is not disposed (the portion that is opposite to the magnetic pole of the magnet) can be made thinner (smaller diameter) than the portion where the magnet is disposed, the motor can be made thinner. Since the yoke and the rotor are disposed close to each other at that portion, it is possible to provide a structure that easily releases heat generated by the rotor from the yoke. Further, the magnetic material is disposed on the inner peripheral surface of the portion between the pair of magnets that constitute the magnetic pole of the yoke, so that the magnetic flux can be concentrated on the portion that becomes the magnetic pole of the yoke. In addition, since the air gap between the rotor and the magnet and the portion where the magnet of the yoke is not provided are substantially the same, the air gap at the facing portion between the rotor and each yoke side can be made uniform. It is possible to reduce the spots and stabilize the rotation of the rotor. Even if a conventional yoke made of a general material is used, the magnetic flux passing through the yoke is not weakened, and there is no problem in the identification of the gap.

  Moreover, the magnetic poles alternate in the circumferential direction by making the circumferential width (arc length) with respect to the rotation direction of the magnet rotor substantially the same as the circumferential width (arc length) of the magnetic pole portion between the magnets of the yoke. This is the same as arranging magnets with the same arc length, and there is no change in the drive control of the motor. Further, since the magnet is made of a rare earth magnet, a small and powerful magnetic force can be obtained, which is effective for miniaturization of the motor. In addition, by using a 4-pole motor, the pair of magnets are disposed at positions facing each other by 180 degrees, and the portion between the pair of magnets of the yoke is located on a line orthogonal to the line passing through both magnets. The length in the direction passing through the portion between the magnets can be easily shortened, and the direction can be reduced in size.

  Furthermore, in the case where the output shaft is provided so as to intersect the rotor shaft, the motor is made thinner with respect to the extending direction of the output shaft by matching the extending direction of the output shaft with the portion between the pair of magnets of the yoke. In an apparatus in which the driven mechanism is disposed ahead of the extending direction of the output shaft, interference with the motor can be easily avoided.

  Thus, since the motor according to the present invention can shorten the radial length of the portion between the pair of magnets of the yoke, for example, in the case of a four-pole motor, the portions between the pair of magnets of the yoke are 180 to each other. Therefore, a thin flat motor can be formed in that direction. In such a flat motor, for example, a wiper motor disposed in a narrow installation space such as in an automobile engine room, or a power window motor disposed in a thin installation space such as an automobile door. By applying, the effect becomes large.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing an automotive wiper motor to which the present invention is applied. As shown in the figure, the motor 1 and the gear box 2 are integrated by connecting the casings to each other.

  The illustrated motor 1 is a four-pole motor, and includes a bottomed cylindrical yoke 3 constituting a casing and a rotor 4 as an armature that is rotatably received in the yoke 3. The rotor 4 includes a rotor shaft 4a, a core 4b made of a laminated electromagnetic steel plate fixed coaxially to the rotor shaft 4a, and a coil 4c wound around the core 4b. One end of the rotor shaft 4a in the axial direction is rotatably supported by a central portion of the bottom of the bottomed cylindrical yoke 3 via a bearing member, and the other end extends from the open end of the yoke 3 into the gear box 2. It is put out and pivotally supported in place.

  A commutator 5 is fixed on the side of the gear box 2 of the rotor shaft 4 a, and a brush holder 7 that supports the brush 6 that is in sliding contact with the commutator 5 is supported by a part of the casing of the gear box 2.

  A worm 8 is integrally provided at the end of the rotor shaft 4a that protrudes into the gear box 2, and the wheel 9 and the worm 8 provided in the gear box 2 are engaged with each other. The wheel 9 is integrally provided with an output shaft 10 that protrudes outward from the gear box 2, and a part of the link mechanism 11 of the wiper device (not shown) is provided at the outward projecting end of the output shaft 10. A tapered serration portion 10a for connecting to the link arm to be formed and a screw portion 10b into which a nut for fixing the link arm is screwed are formed. Therefore, in the illustrated example, the rotor shaft 4a and the output shaft 10 are orthogonal to each other.

  In the motor 1 according to the present invention, as shown in FIG. 2, a pair of magnets provided on the inner peripheral surface of the yoke 3 are disposed so that the same poles (N poles in the illustrated example) face each other. The magnet 12 has an arcuate cross-sectional shape. Since the illustrated example is a four-pole motor, the pair of magnets 12 are disposed to face each other by 180 degrees. The circumferential lengths of these magnets 12 (the length with respect to the rotational direction of the rotor 4b) are about 1/4 of one round (360 degrees).

  The magnets are not disposed in the portions spaced apart from each other in the circumferential direction of the pair of magnets 12, and the portion of the yoke 3 (the portion between the pair of magnets 12) is the magnetic pole of the magnet 12. It is provided as the other-pole constituent part 3a that becomes the opposite magnetic pole. Similarly to the magnet 12, the other-pole component 3a has an inner peripheral surface along the rotating outer peripheral surface of the rotor 4b and is formed in an arc shape having a circumferential length of about 1/4 of one turn (360 degrees). .

  The portion of the yoke 3 to which the pair of magnets 12 are attached is formed in an outwardly bulging shape, and the magnet 12 is attached in the bulging portion 3b, so that the positioning of the magnet 12 in the circumferential direction is also possible. Easy. In the case of the conventional circular yoke, since the magnet can freely move in the circumferential direction, some device for determining the positional relationship with the brush is required. On the other hand, by using the shape as shown in the illustrated example, positioning with respect to the brush only requires fine adjustment, and assemblability is good.

  Further, in the illustrated example, the thickness of the yoke 3 is uniform over the entire circumference, and the inner circumferential surface of the other pole component 3 a is formed so as to extend on the same circumference together with the inner circumferential surfaces of both magnets 12. Has been. Accordingly, in the illustrated example, the gap d between the inner peripheral surfaces of both the magnets 12 and the other pole component 3a and the rotating outer peripheral surface of the rotor 4b is the same.

  In the motor 1 configured as described above, the pair of magnets 12 are disposed so that the same poles face each other. In the illustrated example, an S pole is generated at the point (in the circumferential direction). As a result, the other-pole component 3a acts in the same manner as the provision of a magnet that constitutes a magnetic pole opposite to the magnet 12, and the same magnetic circuit as that of a motor having a four-pole magnet can be formed.

  FIG. 3 shows a winding diagram of the motor 3 according to the present invention. FIG. 3 is a developed view for easy understanding of the relationship between the winding of the coil 4c, each magnet 12, and the other pole component 3a. In the figure, numerals 1 to 12 indicate the 12 teeth of the core 4b and the segments of the commutator 5 for explanation. The number of teeth (12) is also a number that can be changed as appropriate depending on the motor specifications.

  Thus, since the other pole component 3a functions in the same manner as the magnet 12, the number of magnets can be halved as described above. Therefore, the cost of the entire magnet can be reduced, and the overall size and weight can be reduced by thinning the portion where the magnet 12 is not provided.

  In order to achieve motor characteristics equivalent to those provided with magnets on all four poles and to take measures against irreversible demagnetization, the thickness b of the magnet 12 is approximately doubled relative to that provided on all four poles. Therefore, although the number of magnets used is halved, the weight of the whole magnet is not changed, and there is a concern that the effect of reducing the total cost of the magnet is thin. However, if a magnet having a high intrinsic retention force such as a La-Co substituted ferrite magnet 14 is used, the thickness c of the magnet 14 can be made thinner than that of the strontium ferrite magnet, and as shown in FIG. The direction width D and the volume of the motor unit can be reduced, and the mass and cost can be reduced.

  For example, in the case of a wiper motor or a window regulator motor, when the strontium magnet is used, the magnet thickness (b in FIG. 2) is 6 to 10 mm, but the La-Co substituted ferrite magnet 14 is used to increase the magnet thickness. (C in FIG. 7) can be 3 to 7 mm. As a result, as shown in FIG. 7, the width D in the left-right direction of the motor 1 can be made substantially the same as the conventional example. At this time, the intrinsic holding force of the La—Co substituted ferrite magnet is more preferably 300 kA / m or more. The magnet is not limited to a La-Co substituted ferrite magnet as long as its intrinsic holding force is 300 kA / m or more, and is made of a magnet material whose intrinsic holding force can be 300 kA / m or more. It can be a thing.

  In addition, when a sintered Nd magnet is used as the rare earth magnet, if it is formed to a size applicable to a standard size of a power window motor or a wiper motor of a passenger car, the thickness of the magnet due to restrictions in manufacturing the magnet. There is a limit to making (b) thin, and in a conventional structure in which magnets are provided for all four poles, a magnet having a thickness greater than necessary is used.

  In the illustrated example, it is possible to reduce the thickness of the motor 1 with respect to the extending direction of the output shaft 10a orthogonal to the rotor shaft 4a, and there is no problem even if it becomes longer in the left-right direction in FIG. There is no problem even if the thickness b of the magnet 12 is increased. In addition, the thickness that is wasted when the magnets are provided for all four poles is approximately doubled in the present invention, so that the thickness is not wasted. Therefore, when using the same sintered Nd magnet, for example, the mass of the magnet can be reduced with respect to a conventional motor in which magnets are provided for all four poles.

  The outline of the conventional motor 21 in which magnets are provided for all four poles is shown by a two-dot chain line in FIG. The conventional motor 21 shown in FIG. 2 shows a case where the thickness of the magnet 12 is half. When a rare earth magnet is used, the relationship is not half as described above. Also increases radially outward. In any case, as shown in FIG. 2, the length L in the direction of thinning according to the present invention is shorter by M on both sides than the conventional type, and a total reduction of 2M is possible.

  Similarly to FIG. 1, a conventional motor 21 is indicated by a two-dot chain line. If the relationship between the motor 1 of the present invention and the link mechanism 11 of the wiper device remains unchanged, the conventional motor 21 interferes with the link mechanism 11 of the wiper device as shown in the figure. According to the present invention, such interference can be avoided and installation in a narrow place is possible. Therefore, the motor 1 according to the present invention is suitable for a mounted device such as an automobile in which the installation space of the device is desired to be set as narrow as possible. It is.

  According to the present invention, there is no problem even if the thickness of the yoke 3 is made uniform over the entire circumference as in the illustrated example, but a motor that requires more accurate magnetic flux management is formed. In this case, the thickness t1 of the other pole constituent part 3a of the yoke 3 is set to be equal to that of the other part so that the magnetic characteristics of the magnet 12 and the other pole constituent part 3a of the yoke 3 with respect to the rotor 4b are the same with high accuracy. You may make it relatively thick with respect to the thickness t2 (refer FIG. 4).

  Further, a magnetic material such as the iron piece 13 may be separately prepared and attached without changing the thickness of the yoke 3 (see FIG. 5). In this case, the fine adjustment is facilitated by replacing the iron pieces 13 having different thicknesses according to the differences in the motor specifications, and a flexible response is possible.

  Further, the cross-sectional shape of the magnet 12 need not be uniform, and the magnet 12 may be formed so that the back surface on the side opposite to the rotor 4b side is a flat surface (see FIG. 6). In this case, the thickness at both ends in the circumferential direction is thick and the center portion is the thinnest, but the decrease in magnetic force is negligible. By doing so, the amount of protrusion of the yoke 3 in the left-right direction in FIG. 2 can be reduced, so that the layout can be further improved.

  Further, the present invention is not limited to a 4-pole motor, and a cost reduction effect can be expected even if it is applied to a motor having an even number of magnetic poles, such as 6-pole or 8-pole.

  The motor according to the present invention can be thinned in one direction, and is useful when there is a demand to fit in a space as narrow as possible, such as an automobile.

It is a principal part fracture side view showing the wiper motor for vehicles to which the present invention was applied. It is sectional drawing seen along the arrow II-II line | wire of FIG. It is an expanded view which shows the coil | winding structure of the coil based on this invention. It is a figure which shows the other example of the other pole structure part of a yoke. It is a figure which shows another example of the other pole structure part of a yoke. It is a figure which shows the other example of a magnet. It is a figure corresponding to FIG. 2 which shows the example using the La-Co substituted ferrite magnet magnet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Gear box 3 Yoke, 3a Other pole component 4 Rotor, 4a Rotor shaft, 4b Core, 4c Coil 12 Magnet 14 La-Co substitution ferrite magnet

Claims (11)

A motor having a rotor wound with a coil, a cylindrical yoke that coaxially houses the rotor, and a magnet disposed on an inner peripheral surface of the yoke,
The magnet comprises a pair of magnets arranged with the same polarity facing each other,
A portion between the pair of magnets of the yoke is formed to have a surface having substantially the same diameter as the inner peripheral surface of the magnet so as to be a magnetic pole opposite to the magnetic pole of the magnet. Motor. The outer shape of the yoke is formed so that a portion between the pair of magnets is closer to an axis of the yoke than a portion where the pair of magnets are disposed. Motor. 3. The motor according to claim 1, wherein a magnetic body is disposed on an inner peripheral surface of a portion of the yoke between the pair of magnets. 4. The gap between the pair of magnets and the rotor, and the gap between the pair of magnets of the yoke and the rotor are substantially the same. The motor described in. 5. The circumferential length corresponding to the rotational direction of the rotor of the pair of magnets and the portion of the yoke between the pair of magnets is substantially the same. The motor described in. The motor according to any one of claims 1 to 5, wherein the pair of magnets are rare earth magnets. The motor according to any one of claims 1 to 5, wherein the pair of magnets are La-Co substituted ferrite magnets. The motor according to any one of claims 1 to 7, wherein a specific holding force of the pair of magnets is 300 kA / m or more. The motor according to any one of claims 1 to 7, wherein the pair of magnets is made of a magnet material whose intrinsic holding force can be 300 kA / m or more. The motor according to claim 1, wherein the motor is a four-pole motor. An output shaft that transmits the rotational force of the rotor to an external load is provided in a direction crossing the axis of the rotor,
The said output shaft is arrange | positioned so that the extension direction of the said output shaft may be match | combined with the part which becomes between the said pair of magnets of the said yoke. Motor.

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