JPH0747982Y2 - In-hub type brushless spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an in-hub type brushless spindle motor.

[Conventional technology]

Conventionally, magnetic fluid seals have been widely used in in-hub brushless spindle motors used to drive magnetic disks, especially DC brushless spindle motors, in order to prevent grease in internal bearings from flying into the air. Has been.

[Problems to be solved by the device]

Recently, this kind of DC brushless spindle motor
There has been an increasing demand for precision and miniaturization. Therefore, in the in-hub type, it is becoming very difficult to leave even a space for interposing the above magnetic fluid seal.

The object of the present invention is to achieve compactness (miniaturization) in such an in-hub type brushless spindle motor by omitting the magnetic fluid seal and maintaining relatively good sealing performance. The point is to realize a spindle motor.

[Means for Solving the Problems]

The in-hub type brushless spindle motor according to the present invention has a stator fixed to the outer periphery of a fixed pivot shaft.
A rotor magnet is fixed to the inner peripheral side of the hub, the hub is rotatably supported on both ends of the pivot through a pair of bearings, and one end of the pivot is internally attached to the hub. As the substrate is fixed, a sensor for rotor position detection is provided in the circuit portion on the inner surface side of the substrate, and a sensor magnet holding ring having a sensor magnet to be detected by the sensor as an integral part is provided. The substrate is fixed to the inner peripheral side of the hub as opposed to the substrate, and the sensor magnet holding ring and the substrate are sequentially arranged from the bearing on one end side of the pivot shaft outward in the axial direction,
Further, the center hole of the sensor magnet holding ring is formed to have a predetermined length in the axial center direction, and the inner diameter of the center hole is set to be slightly larger than the outer diameter of the pivot shaft so that the center hole A minute circumferential gap portion is formed between the inner circumferential surface and the outer circumferential surface of the pivot shaft, and the inner circumferential surface of the center hole or the outer circumferential surface of the pivot shaft forms the minute circumferential gap portion. A labyrinth groove having a spiral groove shape or a plurality of independent groove shapes was formed.

Further, a stator is fixed to the outer circumference of a fixed pivot shaft, a rotor magnet is fixed to the inner circumference of the hub, and the hub is rotatably supported on both ends of the pivot shaft through a pair of bearings. Then, at one end of the pivot shaft, a substrate is fixed to the hub as an internal condition, and a sensor for detecting the rotor position is provided in the circuit portion on the inner surface side of the substrate, and the sensor to be detected by the sensor. A sensor magnet mounting ring having a magnet fixed thereto is fixed to the inner peripheral side of the hub so as to face the substrate, and the sensor magnet mounting is sequentially performed from the bearing on one end side of the pivot shaft outward in the axial direction. An annular body and a substrate are arranged, a central hole of the sensor magnet mounting annular body is formed to have a predetermined length in the axial direction, and an inner diameter of the central hole is slightly larger than an outer diameter of the pivot shaft. Set a small circumference between the inner peripheral surface of the center hole and the outer peripheral surface of the pivot shaft. Forming a gap portion, the outer peripheral surface of the inner peripheral surface or 該枢 support shaft of said central hole forming a fine small circumferential gap,
A labyrinth groove having a spiral groove shape or a plurality of independent groove shapes was formed.

[Action]

When the labyrinth groove is a spiral groove, the relative rotation between the pivot shaft and the sensor magnet mounting ring or the sensor magnet holding ring causes
A rotating flow that travels inward in the axial direction is generated, and the air present in the minute circumferential gap is affected so as to be drawn into the motor. Therefore, the unclean air inside the motor,
The grease of the bearing is prevented from scattering from the inside of the motor to the outside.

When the labyrinth groove has a plurality of independent grooves, the air present in the minute circumferential gap is large or small due to the relative rotation between the pivot shaft and the sensor magnet mounting ring or the sensor magnet holding ring. A seal layer is formed due to the difference in atmospheric pressure. As a result, the inside and outside of the motor are shut off in a nearly hermetically sealed state, and unclean air inside the motor, grease in the bearing, and the like are prevented from scattering from the inside of the motor to the outside.

Moreover, since the sensor magnet holding ring or the mounting ring has a simple shape, it can be made compact.
Moreover, in the case of having a conventional magnetic fluid seal, the difficult work of supplying the magnetic fluid to the narrow space by a spoid or the like was required, but this can be omitted, and the magnetic fluid is scattered. Secondary air pollution also
It will not occur.

〔Example〕

Hereinafter, the illustrated embodiment will be described in detail. FIG. 1 shows an embodiment in which the left side and the right side of the center line L are separate. In this Fig. 1,
Reference numeral 1 denotes a fixed pivot shaft, on which a hub 3 is rotatably supported via bearings 2 and 2, and a magnetic field is provided between the upper end of the pivot shaft 1 and the upper end of the hub 3 in the illustrated example. The fluid seal 4 is interposed. However, a magnetic fluid seal is completely omitted between the lower end of the pivot shaft 1 and the lower end of the hub 3.

A magnetic storage disk (not shown) is attached to the outer peripheral surface of the hub 3, and an example is a so-called in-hub type brushless spindle motor for driving a magnetic disk. A rotor member 5 is fixed to the inner peripheral surface of the hub 3. The stator 6 is fixed to the center of the pivot shaft 1 and closely faces the rotor magnet 7 on the hub 3 side.

Further, one end 1a of the pivot shaft 1 is internally provided in the hub 3—that is, a state in which it is located inside the opening-side end surface 8 of the hub 3—
The substrate 9 is fixed to the −. As the fixing means, caulking or gluing can be used. Circuit part on the inner surface side of the substrate 9
A sensor 11 for detecting the rotor position is attached to the rotor 10. A Hall element is suitable as the sensor 11.

The sensor magnet 12 to be detected by the sensor 11 corresponds to a part of the annular sensor magnet holding ring 13. That is, the sensor magnet holding ring 13 is formed of the same material as a general magnet material, for example, sintered ferrite, and only a part thereof is magnetized to form the sensor magnet 12. In FIG. 1, the sensor magnet 12 is formed on a part of the outer peripheral edge of the sensor magnet holding ring 13.

The sensor magnet holding ring 13 is fixed to the inner peripheral side of the hub 3 (the inner peripheral surface of the rotor member 5 in the illustrated example) so as to face the substrate 9 and is located on the one end 1a side of the pivot shaft 1. The sensor magnet holding ring 13 and the substrate 9 are arranged in this order from the bearing 2 outward in the axial direction. Further, the center hole 14 of the sensor magnet holding ring 13 is formed to have a predetermined length in the axial direction, and the inner diameter of the center hole 14 is set to the pivot shaft 1
Is set to be slightly larger than the outer diameter of the inner peripheral surface of the central hole 14 and the outer peripheral surface of the pivot shaft 1 to form a minute circumferential gap portion 15 to form a minute circumferential gap portion 15. A labyrinth groove R having a spiral groove shape or a plurality of independent groove shapes is formed on the inner peripheral surface of the center hole 14 or the outer peripheral surface of the pivot shaft 1. The left half of the center line L in FIG. 1 is the case where the labyrinth groove R is formed on the inner peripheral surface of the central hole 14, and the right half of the center line L in FIG. 1 is the outer peripheral surface of the pivot shaft 1. The case where the labyrinth groove R is formed in each is illustrated.

When the labyrinth groove R has a spiral groove shape, the rotation of the sensor magnet holding ring 13 causes a rotational flow that advances inward in the axial direction in the minute circumferential gap portion 15 to generate a small amount of air. Since the air is drawn from the circumferential gap 15 into the motor, unclean air inside the motor, grease of the bearing 2 and the like are prevented from scattering from the inside of the motor to the outside. The spiral direction of the labyrinth groove R and the rotation direction of the sensor magnet holding ring 13 are set so as to exert such a sealing action.

Further, when the labyrinth groove R has a plurality of independent groove shapes, the cross section of the minute circumferential gap portion 15 has an uneven shape, and a large gap portion and a small gap portion are alternately formed, and the sensor magnet holding ring body 13 is formed. By the rotation of the air, the air is blocked by the pressure difference generated in the minute circumferential gap portion 15, and the unclean air inside the motor and the bearing 2
The grease and the like are prevented from scattering from the inside of the motor to the outside.

When one end 1a of the pivot shaft 1 is inserted into the center hole of the substrate 9 and fixed by adhesion or caulking, if a magnetic fluid seal is provided at the position of the sensor magnet holding ring body 13 of the present invention Assuming that, it is difficult to inject the magnetic fluid because the substrate 9 becomes an obstacle. In the present invention, such magnetic fluid injection work can be omitted.

Next, FIG. 2 shows still another embodiment, which is different from the left half and the right half with respect to the center line L.

Also in FIG. 2, the hub 3 is pivotally supported by the pivot shaft 1, the substrate 9 is fixed to one end 1a thereof, and the sensor 11 is provided in the circuit portion 10 on the inner surface side of the substrate 9. Shows a brushless motor type.

Reference numeral 16 denotes a sensor magnet mounting ring body to which the sensor magnet 12 is fixed, which is formed of a metal plate or the like and fixed to the inner peripheral side of the hub 3. The sensor 11 is provided at a position corresponding to the rotation locus of the sensor magnet 12.

The sensor magnet mounting ring (16) faces the base plate (9), and the sensor magnet is sequentially arranged from the bearing (2) on the one end (1a) side of the pivot shaft (1) outward in the axial direction. Mounting ring (1
6) and the substrate (9) are arranged, and further, the center hole (14) of the sensor magnet mounting ring (16) is formed to have a predetermined length in the axial direction,
In addition, the inner diameter of the central hole (14) is set to be slightly larger than the outer diameter of the pivot shaft (1) so that the inner peripheral surface of the central hole (14) and the outer peripheral surface of the pivot shaft (1) are On the inner peripheral surface of the central hole (14) or the outer peripheral surface of the pivot shaft (1) forming a minute circumferential gap portion (15) in the form of a spiral groove or a plurality of grooves. A labyrinth groove (R) having an independent groove shape of a book is formed. Also in this case, if the sensor magnet mounting ring (16) rotates, the same sealing action as that of the motor of FIG. 1 is exerted.

Note that the sensor magnet mounting ring 16
In the case of constructing, the inner cylindrical portion is preferably formed by bending with a press or the like as shown in the figure in order to increase the axial length (width) of the central hole 14. In the right half of FIG. 2, the case where the labyrinth groove R having an independent groove shape is formed on the outer peripheral surface of the pivot shaft 1 is illustrated. Needless to say, the groove may be a spiral groove, and the labyrinth groove R may be freely formed on the inner surface of the mounting ring body 16 forming the central hole 14.

〔effect〕

The present invention has the above-mentioned configuration and has the following remarkable effects.

Without using an expensive magnetic fluid seal, it is sufficient that unclean air inside the motor (inside the minute circumferential gap 15) and grease in the bearing 2 are scattered from the minute circumferential gap 15 to the outside. Can be stopped.

Since a magnetic fluid seal is not required, there is no concern about air pollution due to the scattering of magnetic fluid, and a stable sealing action can be exhibited over a long period of time with excellent reliability.

Since the seal is formed by using the pivot shaft 1 which is a part of the motor component and the sensor magnet holding ring body 13 or the sensor magnet mounting ring body 16, as compared with the motor using the magnetic fluid seal, The number of parts can be reduced, the device can be made compact, and it is suitable for a small motor having a small seal installation space.

The sensor magnet holding ring 13 or the sensor magnet mounting ring 16 may have a simple shape, and the labyrinth groove R may be formed on the pivot shaft 1, the sensor magnet holding ring 13 or the sensor magnet mounting ring 16 before assembly. Since it can be easily formed as a single product, it is easy to manufacture.

In a magnetic fluid seal, after assembling a member that mounts the magnetic fluid seal body and a member on the other side that should hold the magnetic fluid between the magnetic fluid seal body, inject the magnetic fluid into a narrow space. However, in the present invention, if the hub 3 is attached to the pivot shaft 1,
Since the seal structure is automatically completed, the troublesome work described above can be omitted, and the motor can be assembled and manufactured easily and quickly.

[Brief description of drawings]

FIG. 1 is a sectional front view showing an embodiment of the present invention, and FIG. 2 is a partial sectional front view showing another embodiment. 1 ... Pivot shaft, 1a ... One end, 3 ... Hub, 9 ... Substrate,
10 ... Circuit part, 11 ... Sensor, 12 ... Sensor magnet, 13 ...
… Sensor magnet holding ring, 14 …… Center hole, 15 …… Small circumferential gap, 16 …… Sensor magnet mounting ring, R …… Labyrinth groove.

Claims (2)

[Scope of utility model registration request] 1. A stator (6) is fixed to the outer circumference of a fixed pivot shaft (1), and a rotor magnet (7) is fixed to the inner circumference side of the hub (3) to fix the pivot shaft (1). The hub (3) is rotatably supported by a pair of bearings (2), (2) at both ends of the shaft, and is attached to one end (1a) of the pivot shaft (1) and to the hub (3). The substrate (9) is fixed as an internal state, and a sensor (11) for rotor position detection is provided in the circuit portion (10) on the inner surface side of the substrate (9), and the sensor is detected by the sensor (11). A sensor magnet retaining ring (13) integrally having a power sensor magnet (12) as a part is fixed to the inner peripheral side of the hub (3) so as to face the substrate (9), and The sensor magnet retaining ring (13) and the substrate (9) are arranged in this order from the bearing (2) on the one end (1a) side of the support shaft (1) outward in the axial direction, and Sumer magnet holding ring (13)
Of the central hole (14) is formed to have a predetermined length in the axial direction, and the inner diameter of the central hole (14) is set to be slightly larger than the outer diameter of the pivot shaft (1). A central circumferential hole (14) is formed between the inner peripheral surface of (14) and the outer peripheral surface of the pivot shaft (1) to form a minute circumferential gap (15). An inner hub type brushless spindle motor, characterized in that a labyrinth groove (R) having a spiral groove shape or a plurality of independent groove shapes is formed on the inner peripheral surface of (1) or the outer peripheral surface of the pivot shaft (1). 2. A stator (6) is fixed to the outer circumference of a fixed pivot shaft (1), and a rotor magnet (7) is fixed to the inner circumference side of the hub (3) to fix the pivot shaft (1). The hub (3) is rotatably supported by a pair of bearings (2), (2) at both ends of the shaft, and the hub (3) is attached to one end (1a) of the pivot shaft (1). The substrate (9) is fixed as an internal state, and a sensor (11) for rotor position detection is provided in the circuit portion (10) on the inner surface side of the substrate (9), and the sensor is detected by the sensor (11). A sensor magnet mounting ring (16) to which a power sensor magnet (12) is fixed is fixed to the inner peripheral side of the hub (3) so as to face the substrate (9), and the pivot shaft (1) is fixed. The sensor magnet mounting ring (16) and the substrate (9) are sequentially arranged from the bearing (2) on the one end (1a) side outward in the axial direction, and further, the sensor magnet mounting ring ( The center hole (14) of 16) is formed to have a predetermined length in the axial direction, and the inner diameter of the center hole (14) is
Set slightly larger than the outer diameter of the pivot shaft (1),
A center is formed by forming a minute circumferential gap (15) between the inner peripheral surface of the central hole (14) and the outer circumferential surface of the pivot shaft (1), and forming the minute circumferential gap (15). Inner peripheral surface of hole (14) or pivot shaft (1)
An in-hub type brushless spindle motor, characterized in that a labyrinth groove (R) having a spiral groove shape or a plurality of independent groove shapes is formed on the outer peripheral surface of the.