JPS633639A - Brushless dc motor - Google Patents

Abstract

PURPOSE:To make a stator thinner, by bonding a plurality of stator coils arranged on the same circumference, between two large flexible substrates, and by pressing them with a retaining member having a flange smaller than the outer periphery. CONSTITUTION:A plurality of stator coils 40 are arranged on the circumference, and the flexible circuit substrate 42 of a radius which is slightly larger than the outer periphery of the coil is bonded to one surface and a lead wire is led out. On the other surface of the coils 40, a flexible substrate 44 is bonded to form a stator unit 60. A retaining member 62 has an outer diameter equal to that of the circuit substrate 42 and a thickness which is almost equal to the thickness of the stator coils 40, and has the flange section 63 of a diameter smaller than the outer diameter section of the coil 40. The flange section of the retaining member 62 is pushed against the stator unit 60, which is positioned. As a result, a thinner stator with great strength is formed to make a motor thinner.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a brushless DC motor that can be used in magnetic recording and reproducing devices.

BACKGROUND OF THE INVENTION In recent years, brushless DC motors have been desired to be smaller and lighter.

Hereinafter, an example of the conventional brushless DC motor mentioned above will be described with reference to the drawings.

FIG. 3 is a sectional view of a conventional brushless DC motor, and FIG. 4 is an exploded perspective view of the stator section thereof.

In FIGS. 3 and 4, the stator coil 10 is bonded to a printed circuit board 12, and the wire ends are connected to the printed circuit board 12.
It is connected to the copper foil printed on 2. A flexible circuit board 14 made of a flexible member is connected to the printed circuit board 12 and pulled out in any direction to form a stator unit 3o.

On the other hand, a boss 2 to which a back yoke 22 is fixed is attached to a shaft 24 which is supported by a ball bearing 28 in a housing 26.
o is fixed in a predetermined position.

In this state, the stator unit 30 is attached to the housing 26.
A printed circuit board 12 is fixed with screws, and a magnet case 18 holding a rotor magnet 16 is fixed to the end face of a boss 2o passing through the center of the stator unit 3o.

The operation of the conventional brushless DC motor configured as described above will be described below.

First, the magnetic flux of the rotor magnet 16 passes through the stator coil 30 and is focused on the back yoke n.

When the stator coil 10 is energized through the flexible circuit board 14 in this state, the rotor magnet 1
6 and the back yoke 22 rotate together with the shaft 24.

Problems to be Solved by the Invention However, in the above configuration, as shown in FIGS. 3 and 4, the stator unit 30 is placed in the gap between the rotor magnet 16 and the back yoke 22. In order to hold the stator unit 30 without touching the back yoke 22, it is necessary to make the stator unit 30 sufficiently strong. To achieve this, the printed circuit board 12 of the stator unit 30 was made thicker to increase its strength; however, this increased the thickness of the stator unit 30.
The gap T between the rotor magnet 1θ and the back yoke 22 becomes wider, and the magnetic flux of the rotor magnet 16 becomes weaker, which not only makes it impossible to obtain sufficient motor characteristics.
This has the problem that the size of the motor becomes large.

In view of the above-mentioned problems, the present invention does not use a thick printed circuit board, but instead uses a thin flexible circuit board to make the stator unit thinner, improve the characteristics of the motor, and ensure sufficient strength. The present invention provides a brushless DC motor that can be downsized.

Means for Solving the Problems In order to solve the above problems, the brushless DC motor of the present invention includes a plurality of stator coils arranged on the same circumference for rotationally driving the rotor of the motor, a holding member having a flange portion on the outer periphery where the stator coils are arranged and having a smaller diameter than the outer periphery of the plurality of stator coils; a substrate comprising a flexible member having a large diameter and provided with a wiring pattern; and a bearing supporting the rotor of the motor; A portion of the substrate having a diameter larger than an outer circumferential diameter of the plurality of stator coils is clamped, and the flange portion of the pressing member and the bearing are configured to clamp the plurality of stator coils. .

Effect The present invention has a structure in which the stator coil of the stator unit is directly held by the above-described structure, which allows the stator unit to be made thinner while maintaining its strength, and also to ensure the motor characteristics. It becomes possible to make it thinner.

Embodiments Hereinafter, brushless DC motors according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the same essential parts. In FIGS. 1 and 2, stator coils 40 arranged radially are bonded to a flexible circuit board 42 made of a removable member having a chamber diameter larger than the outer diameter of the stator coils 40 arranged radially, The wire ends are connected to a copper foil (not shown) formed on the flexible circuit board 42. A flexible substrate 44 made of a flexible member is bonded to a surface of the stator coil 40 opposite to the surface to which the flexible circuit board 42 is bonded, forming a stator unit 60. The holding member 62 has an outer diameter that is substantially equal to the outer diameter of the flexible circuit board 42, an inner diameter portion that is larger than the outer diameter and has a height that is substantially equal to the thickness of the stator coils 40 that are arranged radially. The flange portion 63 has a smaller diameter than the outer diameter of the stator coil 40.

- On the other hand, a boss 5 to which a back yoke 52 is fixed to a shaft 54 supported by a ball bearing 58 in a housing 56
0 is fixed at a predetermined position.

In this state, the stator unit fixing surface 5 of the housing 56
When the stator unit eo is finally fixed together with the holding member 62 with screws, the outer diameter portion of the flexible circuit board 42 of the stator unit 60 is located between the stator unit fixing surface 57 and the holding member 62, and the radially arranged stators The coil 40 and the flexible circuit board 42 are connected to the stator unit fixing surface 67 and the flange portion e3 of the holding member 62.
It is sandwiched between and fixed.

Furthermore, in this state, the magnet case 48 holding the rotor magnet 46 is fixed to the end face of the boss 50 passing through the center of the stator unit 60.

The operation of the brushless DC motor of this embodiment configured as described above will be described below.

First, the magnetic flux of the rotor magnetometer 46 passes through the stator unit 6o and is focused on the back yoke 52. When the stator coil 4o is energized through the flexible circuit board 42 in this state, the rotor magnet 46 and the back yoke 62 rotate together with the seven shafts 64.

As described above, according to this embodiment, although the flexible circuit board 42 and the flexible board 44 are made of thin and flexible materials, they sandwich the stator coil 40 to form a honeycomb structure. , since it is held between the flange portion 63 of the holding member 62 and the stator unit of the housing 56, /) the fixing surface 5,
Although the stator unit 60 is thin, it is extremely strong. This makes it possible to reduce the gap T between the rotor magnet 46 and the back yoke 52, which not only improves the performance of the motor but also contributes to miniaturization.

Effects of the Invention As described above, according to the present invention, even though the stator coil is bonded to the flexible circuit board, which is a thin and flexible material, the flange portion of the holding member and the stator of the housing Since the stator coil is held between the unit fixing surfaces, the stator unit is extremely strong although it is thin. This makes it possible to reduce the gap between the rotor magnet and the back yoke, which not only improves the performance of the motor but also contributes to miniaturization. Furthermore, the flexible circuit board is also extremely durable because it is clamped and fixed by the holding member and the stator unit fixing surface of the housing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the brushless DC motor of the present invention, FIG. 2 is an exploded perspective view showing the stator section, FIG. 3 is a sectional view showing a conventional brushless DC motor, and FIG.
The figure is an exploded perspective view showing the stator section. 40... Stator coil, 42... Flexible circuit board, 54... Shaft, 56
...Housing, 5 ... Stator unit fixing surface, 58 ... Ball bearing, 62 ...
...Holding member, 63...Flange part. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
−−−−−, is 8 (−11,
-11)

Claims (1)

[Claims] A plurality of stator coils arranged on the same circumference for rotationally driving a rotor of a motor, and a flange portion having a diameter smaller than the outer periphery of the plurality of stator coils on the outer periphery where the stator coils are arranged. and a flexible member having a diameter larger than the outer circumferential diameter of the plurality of stator coils to which the plurality of stator coils are bonded and provided with a wiring pattern. and a bearing member that supports the rotor of the motor, and the pressing member and the bearing member clamp a portion of the substrate having a diameter larger than the outer circumferential diameter of the plurality of stator coils, and the pressing member A brushless DC motor characterized in that the plurality of stator coils are sandwiched between a flange portion and a bearing member.