JP2539861Y2 - Rotor device of brushless motor - 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 rotor device used for a spindle motor for a floppy disk, a cylinder drum motor for a VTR, and the like.

[0002]

2. Description of the Related Art In recent years, OA equipment, audio and video equipment have become lighter and smaller, and the structure of a motor, which is a component of a central part of a drive control mechanism, has been required to be smaller and thinner.

[0003] A conventional brushless motor rotor device will be described below. FIG. 3 shows a sectional view of a spindle motor for a floppy disk as an example of a rotor device of a conventional brushless motor. In FIG. 3, 1 is a shaft, 2 is a spindle hub, 3 is a hub magnet, 4 is a drive pin, 5 is a link, and 6 is a link support. Reference numeral 7 denotes a rotor frame, 8 denotes a magnet (hereinafter abbreviated as a PG magnet) for generating a pulse signal (hereinafter abbreviated as a PG signal) per one rotation of the rotor, and 9 denotes a magnetic sensing element (generally, a PG magnet). Hall element, Hall IC), 10 is a main magnet, 11 is a frequency power generation magnet (hereinafter abbreviated as FG magnet). Further, 12 is an armature coil, 13 is an armature core, 14 is a stator substrate, 15
Is a housing.

[0004] The operation of the rotor device of the brushless motor configured as described above will be described below.
First, the disk hub is magnetically attracted to the hub magnet 3 as the disk is inserted into the floppy disk device, and the drive pin 4 is chucked in the disk insertion hole while the motor starts rotating and the rotor makes one rotation. The motor and the disk rotate together. On the other hand, when the rotor starts to rotate, the FG magnet 11 attached to the flange portion obtained by bending the open end face of the rotor frame 7 at a substantially right angle and the power generation wire element arranged opposite to the FG magnet 11 cause a motor rotation speed signal (hereinafter, referred to as a motor speed signal). FG signal), the rotation of the motor is controlled, and at the same time, the magnetic flux is generated each time the rotor is rotated by the PG magnet 8 and the magneto-sensitive element 9 (generally a Hall element, Hall IC) opposed thereto. Is detected, and an index pulse signal (hereinafter referred to as P
(Abbreviated as G signal), and the disk information is read out or the write position on the disk is detected.

[0005]

However, in the above-described conventional configuration, the main magnet and the FG are mounted on one rotor frame while the motor is made thinner with the thinner FDD.
In order to dispose magnets and PG magnets, the open end face of the rotor frame is bent substantially at a right angle to form a flange portion, and FG magnets and PG magnets are attached to this portion. It becomes impossible to form a magnetic circuit, which causes a decrease in motor torque. In addition, the FG magnet has to be made thinner and the PG magnet must be made smaller, which causes problems such as a decrease in FG signal output and PG signal output due to a decrease in magnetic flux density, and an increase in leakage magnetic flux due to exposure of the PG magnet. I was

The present invention solves the above-mentioned conventional problems, and provides a rotor device of a brushless motor that can realize a thin motor while maintaining the control performance, torque characteristics, and leakage magnetic flux characteristics of the motor. The purpose is to:

[0007]

In order to achieve this object, a rotor device for a brushless motor according to the present invention provides a rotor frame having a continuous curvature with a certain curvature without cutting an open end surface of a cup-shaped rotor frame. , A flange is formed by providing a step with the open end face, an FG magnet is provided in the rotor frame, a notch is provided in a part of the FG magnet, and a PG magnet is provided.

[0008]

With this configuration, a complete magnetic circuit of the main magnet can be formed, and the magnetic flux is increased by increasing the thickness of the FG magnet. A notch is provided in one part of the FG magnet and the PG magnet is provided. In addition, it is possible to make the motor thinner while preventing the inertia of the rotor from lowering, and maintaining the motor control performance, torque characteristics, and leakage magnetic flux characteristics.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a spindle motor for FDD as an example of a rotor device of a brushless motor according to an embodiment of the present invention. FIG. 2A is a sectional view of the rotor device, and FIG. FIG. 4 is a plan view of the rotor as viewed from the tip.

In FIG. 1, 1 is a shaft, 2 is a spindle hub, 3 is a hub magnet, 4 is a drive pin, 5 is a link, and 6 is a support. 7 is a rotor frame, 8 is a PG magnet, 9 is a magneto-sensitive element, 10 is a main magnet, 1
1 is an FG magnet.

The operation of the rotor device of the brushless motor configured as described above will be described below. First, as the disk is inserted into the FDD device, the disk hub is attracted to the hub magnet 3 and the drive pin 4 is chucked in the disk insertion hole while the motor starts to rotate and the rotor makes one rotation. The rotor rotates together with the rotor. Fig. 2 When the rotor starts to rotate
As shown in (a), F is formed on a flange portion 7b formed by folding back from the rotor frame open end portion 7a.
The rotation speed signal of the motor can be obtained by the G magnet 11 and the power generating element arranged opposite thereto.
(B) A PG signal is generated once per rotation of the rotor by the PG magnet 8 and the magneto-sensitive element 9 fixed to the protrusion 7c and the FG magnet notch 11a at the tip of the flange portion 7b of the rotor frame 7. Incidentally, in the above embodiment, the hub magnet 3 and the FG magnet 11 are made of a magnetic material such as rubber or resin, and are fixed to the rotor frame 7 by bonding, adhesive tape or integral molding. The PG magnet 8 is bonded or press-fitted to the rotor frame protrusion 7c and the notch 11a of the FG magnet.

As described above, according to the present embodiment, the rotor frame open end 7a is folded along the outer peripheral surface of the rotor frame continuously and with a certain curvature without cutting.
The flange portion 7b is formed by providing a step with the open end face,
If the magnet 11 and the PG magnet 8 are integrally formed, the rotor inertia is prevented from lowering, the motor control performance is maintained, and the FG magnet 8 is secured with a sufficient volume to achieve FG.
The motor is improved without deteriorating the characteristics such as improvement of the S / N ratio of the signal, the shielding effect of the rotor frame projections 7c for reducing the leakage magnetic flux of the PG magnet 8, and the maintenance of the motor torque by the complete magnetic circuit configuration of the main magnet 10. Can be reduced in thickness.

[0014]

As described above, according to the present invention, the open end of the rotor frame is formed with a certain curvature without cutting, and the extended surface of the open end of the rotor frame is folded back along the outer peripheral surface of the rotor frame to open the rotor frame. A flange surface is formed by providing a step with the end surface, and an FG magnet, a PG
By configuring the magnet, the motor can be made thinner while maintaining the conventional motor control performance, torque characteristics, and leakage magnetic flux characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view of a brushless motor according to an embodiment of the present invention;

2A is a cross-sectional view of the rotor device according to the embodiment of the present invention. FIG. 2B is a plan view of the rotor device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional brushless motor.

[Explanation of symbols]

 Reference Signs List 1 shaft 2 spindle hub 3 hub magnet 4 drive pin 5 link 6 support 7 rotor frame 7a rotor frame open end 7b rotor frame flange 7c rotor frame protrusion 8 PG magnet 9 magneto-sensitive element 10 main magnet 11 FG magnet 11a FG magnet Notch 12 Armature coil 13 Armature core

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-92117 (JP, A) JP-A-58-184667 (JP, U) JP-A-2-22068 (JP, U) JP-A 61- 32779 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A motor generator comprising a cup-shaped rotor frame, a cylindrical field magnet mounted on an inner peripheral surface of the rotor frame, and a frequency power generation magnet and a position detector on an outer peripheral side of an open end surface of the rotor frame. A rotor device having a magnet for use in a brushless motor, wherein the open end surface of the rotor frame is continuously cut without cutting the open end surface along the outer peripheral surface of the rotor frame with a certain curvature, and the open end surface is provided with a step to provide a flange portion. And a magnet for frequency generation and a magnet for position detection are arranged on the flange portion. A rotor device for a brushless motor.