JP3439318B2 - Brushless motor and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor and a method of manufacturing the same, and more particularly to a structural technique for stabilizing the runout of a rotary shaft.

[0002]

2. Description of the Related Art Among various conventional motors, VT
In an R capstan motor or the like, a stator core is fixed to the side of a motor substrate that serves as a motor base, and a drive coil is wound around salient poles of the stator core. A bearing is also fixed to the side of the motor board, and a rotating shaft that rotates integrally with the rotor case is supported by the bearing. A rotor magnet is fixed to the inner peripheral surface of the rotor case so as to face the outer peripheral surface of the stator core, and the rotor is rotated by the magnetic force generated between the rotor magnet and the drive coil.

Here, an inexpensive sintered oil-impregnated bearing is being used as the bearing in place of the ball bearing, but in the sintered oil-impregnated bearing, there is a relatively large clearance with the rotating shaft, so that the rotor rotates. At this time, irregular run-out like a rubbed motion is likely to occur on the rotary shaft. As a technique for preventing such an irregular swing of the rotating shaft, Japanese Utility Model Publication No. 5-10547 discloses a recessed portion of a yoke plate (iron plate) which is formed by subjecting a region facing a rotor magnet to a drawing process. There is disclosed an invention in which the rotor is always attracted to one side by forming a convex portion or a convex portion and making the magnetic attraction force generated between the rotor magnet and the yoke plate strong or weak. In Japanese Utility Model Laid-Open No. 4-58065, magnetic powder is applied to only one side of the motor substrate with respect to the rotational center position of the rotor, and the magnetic powder is generated between the magnetic powder and the rotor magnet. An invention is disclosed in which the rotor is always attracted to one side by utilizing a magnetic attraction force.

[0004]

[Problems to be Solved by the Invention] However, the above 2
Of the two inventions, in the method of forming the concave portion and the convex portion by subjecting the yoke plate to the drawing, since the unevenness cannot be formed deeper or higher, the magnetic attraction force generated between the rotor magnet and the yoke is reduced. As mentioned above, there is a problem in that it is not possible to attach great strength. Also, if a wiring pattern is printed on the surface of the yoke plate via an insulating film and it is used as a motor substrate, the wiring pattern is peeled off when the unevenness is formed on the yoke plate. There is a problem that such a technique cannot be applied. on the other hand,
The method of applying the magnetic powder on the motor substrate has a problem in that the work for it is troublesome.

In view of the above problems, the object of the present invention is to
Even if you do not use the unevenness formed by drawing on the yoke plate,
In addition, even if a new process such as applying magnetic powder is not added, a wiring pattern is formed on the base of the motor so that the base of the motor can be used as a circuit board. It is to provide a brushless motor capable of reliably preventing such a runout at low cost, and a manufacturing method thereof.

[0006]

In order to solve the above problems, in the present invention, a drive coil held on the base side,
A bearing held on the side of the base body and a bearing supported on the side of the base body via a rotation shaft rotatably supported by the bearing, and the magnetic force generated between the drive coil and the rotor magnet on the base body. In a brushless motor having a rotor that rotates at a center, the base is made of a magnetic plate and a resin.
The drive coil is formed on the magnetic plate.
Terminal part to which the end of the cable is connected by wiring, and extending from the terminal part
The exposed wiring pattern and the rotor magnet.
Of the rotation center position of the rotor.
Unevenly distributed in the area on one side and pulls the rotor to the one side.
Generate a magnetic attraction force between the rotor magnet and
And a rotor suction portion is formed .

In the brushless motor according to the present invention, in the area facing the rotor magnet on the side of the base body made of the integrally molded product of the magnetic plate and the resin, the area on one side of the rotation center position of the rotor is provided. A rotor suction portion formed of a part of the magnetic plate is arranged, and the rotor suction portion is
A magnetic attraction force is generated between the rotor magnet and the rotor magnet. Therefore, since the magnetic attraction force acting on the rotor magnet has strength depending on the location depending on the presence or absence of the rotor attraction portion, the rotor attraction portion pulls the rotor to one side. Therefore, even if there is a relatively large clearance between the bearing and the rotary shaft, the rotary shaft is always in the state of being subjected to the lateral pressure, so that irregular runout does not occur. Moreover, since the magnetic attraction force acting on the rotor magnet is regulated depending on the presence or absence of the rotor attraction portion, this is different from the case where the gap between the rotor magnet and the magnetic plate is widened by the unevenness formed by drawing on the magnetic plate. Therefore, the magnetic attraction can be greatly enhanced. Therefore, it is possible to reliably prevent irregular runout of the rotating shaft. In addition, the conductive plate material and the resin forming the wiring pattern are integrally molded,
When the base body is configured as a circuit board, a magnetic plate is used as a plate material, and a part of the magnetic plate constitutes the rotor suction portion. That is, since the rotor suction unit is configured by directly using the process for configuring the base body as the circuit board, the number of processes does not increase. Therefore, the runout of the rotating shaft of the brushless motor can be prevented at low cost.

In the present invention, a wide arc portion corresponding to the shape of the rotor magnet is formed in a part of a region facing the rotor magnet with respect to the wiring pattern.
The wide arc portion may be used as it is as the rotor suction portion.

In the present invention, it is preferable that the magnetic plate is manufactured at low cost by press working.

In manufacturing the brushless motor having such a structure, a plate material as a raw material of the magnetic plate is pressed to connect the terminal portion, the wiring pattern, and the rotor suction portion to the frame portion. A pressing step to form, and of the plate material that has undergone the pressing step, the terminal portion, the wiring pattern, and the rotor suction portion are housed in a mold and resin molding is performed in the mold to form a resin molded product. A molding step of forming a resin molding product into the base by separating the terminal portion, the wiring pattern, and the rotor suction portion from the frame portion; bearing,
And an assembling process of mounting the rotor. That is, since it is not necessary to add a new process such as applying the magnetic powder, it is possible to inexpensively manufacture the brushless motor in which irregular runout does not occur on the rotating shaft.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless motor to which the present invention is applied will be described with reference to the drawings.

(Overall Structure) FIGS. 1A, 1B, and 1C
Are respectively a plan view of a brushless motor 1 to which the present invention is applied, a partial sectional view taken along the line II ', and a line II-I thereof.
It is a fragmentary sectional view in the I'line.

As shown in FIGS. 1A, 1B, and 1C, the brushless motor 1 of this embodiment is a VTR capstan motor, and a stator substrate 2 has a cylindrical protrusion at its central portion. 20 are formed. The sintered oil-impregnated bearing 3 is held inside the central hole of the protrusion 20, and the stator core 4 is fitted on the outside of the protrusion 20. Three phases (U phase, V phase, W phase) for each salient pole of the stator core 4.
The drive coil 5 is wound. A rotary shaft 61 of the rotor is rotatably supported by the sintered oil-impregnated bearing 3, and
A rotor case 62 is fixed to the. A ring-shaped rotor magnet 63 is fixed to the inner peripheral surface of the side surface of the rotor case 62 so as to face the outer peripheral surface of the stator core 4. Therefore, due to the magnetic force generated between the rotor magnet 63 and the drive coil 5, the rotor case 62 is
Rotates integrally with the rotating shaft 61. Here, a pulley 64 is formed on the upper surface of the rotor case 62.
The brushless motor 1 transmits a driving force via a belt (not shown) hung on the belt 4.

(Structure of Stator Substrate 2) FIG.
(B) and (C) are each a stator substrate (base / core holder) used in the brushless motor to which the present invention is applied.
Plan view of III, a cross-sectional view along the line III-III ′, IV
FIG. 4 is a cross-sectional view taken along the line IV ′.

In this embodiment, the stator board 2 is also used as a circuit board for supplying power to the drive coil 5. That is, as shown in FIGS. 2A to 2C, the stator substrate 2 stands up at four locations around the protrusion 20 and ends of the drive coil 5 of each phase (U phase, V phase, W phase). Are connected to each other, and three terminal portions 71, 72, 73 are connected to each other, and one terminal portion 74 to which all terminals of the three-phase drive coil 5 are connected to each other by common wiring is formed. Terminals 71 to 7 respectively
Wiring patterns 75, 76, 77, 7 from the lower end of 4
8 are integrally extended, and each wiring pattern 75, 76, 7
External terminal portions 751, 761, 77 are provided at the end portions of 7, 78.
1, 781 and 782 are respectively configured. These external terminal portions 751, 761, 771, 781, 782
Of these, the external terminal portions 751, 761, 771 of each phase and the common external terminal portion 781 are arranged so as to project from one end edge 21 of the stator substrate 2, and the common external terminal 782 of the stator substrate 2 is arranged. It is arranged so as to project from the other edge 22.

The above-mentioned four terminal portions 71 to 74 and 4
As will be described later, each of the two wiring patterns 75 to 78 is formed by insert molding after pressing one iron plate (magnetic plate). That is, the stator substrate 2 is an iron plate 70 (magnetic plate) that forms the four terminal portions 71 to 74 and the four wiring patterns 75 to 78.
And a resin 80 having high heat resistance such as PBT, PPS, or nylon 66 (insert mold substrate), and most of the wiring patterns 75 to 78 are almost entirely made of resin on the surface of the stator substrate 2. 80
Is exposed from the portion (in FIG. 2A, this exposed portion is shaded).

On the surface side of the stator substrate 2, a reinforcing rib 89 formed so as to surround the outside of the rotor case 62.
Is protruding. In addition, a thin insulating film is formed on the surface of the stator substrate 2, and the wiring patterns 75 to 7 are formed by the thin insulating film.
8 may be covered in some cases.

Here, the formation regions of the four wiring patterns 75 to 78 are arranged so as to be unevenly distributed in one region of the region facing the rotor magnet 63 with respect to the rotation shaft 61 of the rotor 6. . That is, of the four wiring patterns 75 to 78, the wiring pattern 78 for setting the terminal of the drive coil 5 to the common potential is provided on one side with respect to the rotary shaft 61 of the rotor from one edge 21 of the stator substrate 2. Although it is formed so as to reach the other end edge 22 through, the portion passing through a region facing the rotor magnet 63 is a wide arc portion 79. Therefore, the rotor magnet 63 and the wide arc portion 79 of the wiring pattern 78 face each other with a wide area. On the other hand, the other portion of the common wiring pattern 78 has a narrow width, and all of the other three wiring patterns 75 to 77 are narrow patterns. In the region excluding, the facing area between the rotor magnet 63 and the wiring patterns 75 to 78 is extremely narrow.

(Effect of this embodiment) In the brushless motor 1 thus configured, since the inexpensive sintered oil-impregnated bearing 3 is used as a bearing for supporting the rotating shaft 61, the inner circumferences of the rotating shaft 61 and the sintered oil-impregnated bearing 3 are used. There is a relatively large clearance between the surfaces. Therefore, in the structure as it is, the rotor 6
When the rotating shaft rotates, the rotating shaft 61 tends to cause irregular runout in the sintered oil-impregnated bearing 3. However, in the present embodiment, in the region facing the rotor magnet 63, the region on the one side with respect to the rotation center position (rotation shaft 61) of the rotor 6 has the wide width of the wiring pattern 78 formed of a part of the iron plate. A circular arc portion 79 is arranged, and this wide circular arc portion 79 functions as a rotor attraction portion that generates a magnetic attraction force (indicated by an arrow B) with the rotor magnet 63. Therefore, the magnetic attraction force acting between the stator substrate 2 and the rotor magnet 63 is strong on the side where the wide arc portion 79 is present and does not exist on the opposite side. That is, since the magnetic attraction force acting between the stator substrate 2 and the rotor magnet 63 has strength depending on the location depending on the presence or absence of the wide arc portion 79,
The stator substrate 2 (wide arc portion 79) pulls the rotor 6 to one side. As a result, even if there is a relatively large clearance between the sintered oil-impregnated bearing 3 and the rotary shaft 61, the rotary shaft 61 is always in the state of being subjected to the lateral pressure as indicated by the arrow C. Irregular swings such as exercise do not occur. Moreover, the rotor magnet 6
The strength of the magnetic attraction force acting on No. 3 is defined by the presence or absence of the wide arc portion 79 as the rotor attraction portion, so that the magnetic attraction force can be greatly affected.

(Manufacturing Method of Brushless Motor 1) The brassless motor having such a structure is manufactured by the method described below.

In the method for manufacturing the brushless motor 1 according to the present embodiment, first, a large iron plate is subjected to press working, and as shown in FIG. 3, terminal portions 71 to 74, wiring patterns 75 to 77, and rotor suction. A wiring pattern 78 having a wide arc portion 79 that serves as a part is punched in a state of being connected to a rectangular frame portion 701 (pressing step). Further, the terminals 71 to 74 are processed so as to stand them up.

Next, in the iron plate 700 that has undergone the pressing process, the wiring pattern 78 having the terminal portions 71 to 74, the wiring patterns 75 to 77, and the wide arc portion 79 is housed in the die and is housed in the die. Resin molding is carried out to form a resin molded product (molding step). Of course, the terminals 71 to 74 are made of resin 80 so that the coil wiring can be connected later.
Do not cover with. Note that, in FIG. 3, the outer peripheral contour of the resin molded product is represented by a one-dot chain line L.

Next, the wiring pattern 78 including the wiring patterns 75 to 77 and the wide arc portion 79 is separated from the frame portion 701 at a position indicated by an arrow F to form a resin molded product, and the stator substrate 2 shown in FIG. Shaping (shaping process).

Next, as shown in FIG. 1, the stator substrate 2
Then, the drive coil 5, the sintered oil-impregnated bearing 3, and the rotor 6 are mounted (assembly process).

As described above, the steps for forming the stator substrate 2 as a circuit board are used as they are to form the rotor suction portion (wide arc portion 79), so that the number of steps does not increase. Therefore, irregular runout of the rotary shaft 61 of the brushless motor 1 can be prevented at low cost. Therefore,
When the brushless motor 1 is mounted on a set as a VTR captan motor, the direction in which the lateral pressure is applied as indicated by the arrow C in FIG. 1B and the direction in which the belt is stretched by the pulley 64 (arrow E) are set. The brushless motor 1 is arranged in the same direction.

[Other Embodiments] In the above embodiment, the common wiring pattern 78 is provided with the wide arc portion 79 serving as the rotor suction portion, but the other wiring patterns 75 to 77 are provided. A wide arc portion 79 that serves as a rotor suction portion may be provided.

Further, the portion to be the rotor suction portion may be electrically insulated from any of the wiring patterns 75 to 78. To do this, a large iron plate is pressed to form terminal portions 71 to 74 and wiring patterns 75 to 78 as shown in FIG. The arc portion 79 may be formed. In this case, since the wide arc portion 79 (rotor suction portion) is separated from the wiring patterns 75 to 78, the wide arc portion 79 and the frame portion 701 are connected to each other by the connecting portion 702 before insert molding. Connected through
After insert molding, the connecting portion 702 is cut off at the position indicated by arrow F. Even with such a configuration, as described with reference to FIG. 1B, the magnetic attraction force acting on the rotor magnet 63 has a wide arc portion 79 (rotor attraction portion).
Since there is strength depending on the location depending on the presence or absence of "," the rotor 6 is pulled to one side. Therefore, even if there is a relatively large clearance between the sintered oil-impregnated bearing 3 and the rotary shaft 61,
Since the rotating shaft 61 is always in the side pressure state, it has the same effects as those of the above-described embodiment, such as no irregular shake. Further, although the wide circular arc portion 79 is separated and independent from the wiring patterns 75 to 78, the process for forming the stator substrate 2 as a circuit substrate is directly used as in the above-described embodiment. Since it is formed as described above, it is not necessary to increase the number of manufacturing steps, and it is possible to inexpensively prevent the rotation shaft 61 of the brushless motor 1 from swinging.

Further, the stator substrate 2 may be configured as a part of the chassis of the set (electrical product), not as the base of the motor.

[0029]

As described above, in the brushless motor according to the present invention, the center of rotation of the rotor is located in the area facing the rotor magnet on the side of the base body made of the integrally molded magnetic plate and resin. On the other hand, it is characterized in that the rotor suction part formed of a part of the magnetic plate is arranged in the region on one side. Therefore, according to the present invention, the rotor attracting portion attracts the rotor to one side by generating a large magnetic attracting force having strength depending on the location. Therefore, even if there is a relatively large clearance between the bearing and the rotary shaft, the rotary shaft is always in the state of being subjected to the lateral pressure, so that irregular runout does not occur. Further, since the rotor suction unit is constructed by directly using the process for constructing the base body as the circuit board, the number of processes does not increase.
Therefore, the runout of the rotating shaft of the brushless motor can be prevented at low cost.

[Brief description of drawings]

1A, 1B, and 1C are respectively a plan view of a brushless motor to which the present invention is applied, a partial cross-sectional view taken along line I-I ', and a partial cross-sectional view taken along line II-II' thereof. Is.

2A, 2B, and 2C are respectively a plan view of a stator substrate used in the brushless motor 1 to which the present invention is applied, a cross-sectional view taken along line III-III 'thereof, and IV-I thereof.
It is a sectional view taken along the line V ′.

FIG. 3 is a plan view showing a state after pressing an iron plate to form the stator substrate shown in FIG.

FIG. 4 is a plan view showing a state after pressing an iron plate to form a stator substrate used in another brushless motor to which the present invention is applied.

[Explanation of symbols]

1 brushless motor 2 Stator substrate (base) 3 Sintered oil-impregnated bearing 4 Stator core 5 drive coil 6 rotor 61 rotation axis 62 rotor case 63 rotor magnet 64 pulley 70 Iron plate (magnetic plate) 71-74 Terminal 75-78 wiring pattern 79 Wide arc part (rotor suction part) 80 resin 89 Reinforcing rib 700 Iron plate after pressing process 701 frame part

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K 29/00 H02K 5/22 H02K 15/02 H02K 21/22 H02K 7/04

Claims (4)

(57) [Claims] 1. A drive coil held on the side of the base body, a bearing held on the side of the base body, and a support shaft supported on the side of the base body via a rotary shaft rotatably supported by the bearing, In a brushless motor having a rotor that rotates on the base due to a magnetic force generated between a drive coil and a rotor magnet, the base is made of an integrally molded product of a magnetic plate and a resin.
Is, wherein the magnetic plate, the ends of the drive coils are hardwired
Terminal part, a wiring pattern extending from the terminal part, and
Of the area facing the rotor magnet and the rotor magnet.
Is unevenly distributed on one side of the rotation center position of the rotor.
The magnetic attraction force that draws the rotor to one side is applied to the low side.
The rotor suction part that is generated between the
The brushless motor is characterized by 2. The wiring pattern according to claim 1, wherein a wide arc portion corresponding to the shape of the rotor magnet is provided in a part of a region facing the rotor magnet, and the rotor attraction portion is constituted by the arc portion. Brushless motor characterized by being 3. The brushless motor according to claim 1, wherein the magnetic plate is manufactured by press working. 4. The method of manufacturing a brushless motor according to claim 1, wherein a plate material that is a raw material of the magnetic plate is pressed to form the terminal portion, the wiring pattern, and the rotor suction portion. A pressing step of forming in a state of being connected to a frame section, and among the plate materials that have undergone the pressing step, the terminal section, the wiring pattern, and the rotor suction section are housed in a mold and a resin is housed in the mold. A molding step of molding to form a resin molded product,
A shaping step of separating the terminal portion, the wiring pattern, the rotor suction portion from the frame portion and shaping the resin molded product into the base body, and mounting the drive coil, the bearing, and the rotor on the base body. A method of manufacturing a brushless motor, comprising: