JP2536471Y2 - 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 motor. More specifically, the present invention relates to a rotor for a high-speed rotating motor such as a laser scanning motor or a high-speed spindle motor, and a mounting structure for a driving magnet and a yoke fixed thereto.

[0002]

2. Description of the Related Art High-speed rotating motors such as a laser scanning motor, a magnetic drum motor, a gyro motor, and a high-speed spindle motor require dynamic pressure air generated with the rotation to enable high-speed rotation. A dynamic pressure air bearing that supports the rotor is adopted. In this dynamic pressure air bearing, for example, a spiral dynamic pressure generating groove is formed on any one of an outer peripheral surface of a rotor and an inner peripheral surface of a cylindrical bearing member that supports the rotor, and the rotor and the bearing member are formed. Between them. This dynamic pressure air bearing generates dynamic pressure during rotation to levitate and support the rotor. Therefore, a very narrow fixed bearing gap between the rotor and the bearing member (in the figure, the bearing gap is exaggerated but is usually , Several μm to tens of μ
m) is formed. Therefore, when a predetermined bearing gap cannot be accurately secured between the rotor and the bearing member, they contact each other to generate frictional heat and cause a so-called seizure phenomenon in which the shaft and the bearing adhere to each other due to melting of the contact portion. There is a risk of starting. Therefore, the production of the rotor and the bearing member requires sufficient roundness and squareness accuracy.

On the other hand, in a high-speed rotating motor such as a laser scanning motor, a driving magnet yoke, a driving magnet and the like are fixed inside a cylindrical rotor by an adhesive applied on the entire surface, and a stator coil is further provided inside. In addition, it is conceived that a motor is made more compact and the deflection and inclination of the rotating shaft are reduced as much as possible by disposing an iron core and the like. In the case of a hydrodynamic air bearing with such a structure, the shape and structure of the rotating shaft becomes complicated, so hardened steel is used as the rotor material, and it is created by turning an aluminum alloy rather than grinding it. This is much more advantageous in terms of processing cost.
Therefore, it is desired that both the rotating shaft and the bearing member be made of aluminum or an aluminum alloy.

[0004]

However, when the rotor is made of aluminum or an aluminum alloy, there is a problem that it is relatively soft and relatively easily deformed by the action of an external force, so that the above-mentioned bearing gap cannot be maintained. That is, as shown in FIG. 3, conventionally, a driving magnet yoke 102, a driving magnet 103, a FG magnet yoke 104, an FG magnet 105, a spacer 106, and the like are provided on an inner peripheral wall surface of an aluminum cylindrical rotor 101. Each is entirely bonded by an adhesive 107. For this reason, the force due to the contraction of the adhesive during curing acts throughout the rotor, deforming the vicinity of the relatively weak opening end of the rotor, affecting its accuracy (roundness / squareness). The product yield is poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor having a structure that does not affect the accuracy of the rotor by bonding a magnet yoke or a magnet to the rotor.

[0006]

In order to achieve the above object, the present invention provides a bottomed cylindrical rotor whose one end is open and the other end is partially or completely closed by a bottom wall, and is rotatable. A dynamic pressure bearing is formed between the rotor and the bearing member, and a driving yoke and a driving magnet are fixed to the inner surface of the rotor, and a stator core and a stator coil are further disposed inward. At least one circumferential annular groove is provided on the inner peripheral surface, and an adhesive is applied to a deeper portion closer to the bottom than the groove to fix a drive magnet, a yoke, and the like to the rotor.

In the motor of the present invention, the rotor is made of aluminum or an aluminum alloy.

[0008]

Therefore, even if a force is applied to deform the rotor due to shrinkage during curing of the adhesive, it occurs only in the vicinity of the bottom reinforced by the bottom wall, so that the rotor is not deformed. Further, the partially applied adhesive is stopped by the circumferential annular groove, and does not flow out to a portion near the opening end which is easily deformed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIG. 1 shows a schematic structure of a rotor used in the motor of the present invention. This rotor 1 has one end opened,
The other end has a bottomed cylindrical shape partially closed by a bottom wall 1b, and has a rotor magnet yoke 2, a rotor magnet 3, a frequency power generation magnet yoke (FG magnet yoke) 4, and a frequency power generation magnet ( The FG magnet 5 and the spacer 6 are fixed by an adhesive 8 (a portion indicated by a thick line in the figure). The rotor 1 is made of, for example, aluminum or an aluminum alloy, and has one or more, for example, two annular grooves 7 formed in the circumferential direction near the bottom of the inner peripheral surface 1 _fi .
7 divides into a fixed region 9 and a non-fixed region 10. The grooves 7, 7 are not particularly limited in their shape, number, and size, but at least the non-fixed area 9 of the adhesive 8 applied to the fixed area 9 closer to the bottom side than that.
It is preferable to have a sufficient volume to prevent outflow to the air.

An adhesive 8 is applied to the fixing region 9 and the FG
The magnet yoke 4, the FG magnet 5, the spacer 6, and the rotor magnet yoke 2 are fixed as required. The FG magnet 5 is fixed to the entire surface of the FG magnet yoke 4 with an adhesive 8. Furthermore, this FG
A spacer 6 is fixed between the magnet 5 and the rotor 1. The spacer 6 is for magnetically shielding the FG magnet 5 and the rotor magnet 3, and is made of a non-magnetic material. An adhesive 8 is applied to the inner peripheral surface side of the rotor magnet yoke 2 partially or entirely, and the rotor magnet 3 is fixed thereto.

The rotor 1 has one end opened, but the other end has a bottom wall 1b orthogonal to the cylindrical portion. This portion provides a rib effect to reduce the resistance to deformation due to shrinkage of the adhesive 8. It is provided so that it becomes. On the other hand, a spiral dynamic pressure generating groove (not shown) is formed on the outer peripheral surface 1 _{fo of the} rotor 1 (or the inner peripheral surface of a cylindrical bearing member constituting a dynamic pressure bearing with the rotor 1). The bearing is provided so as to support the bearing load by increasing the pressure of the fluid in the bearing gap, for example, air or other gas or oil or other liquid, by a spiral groove with the rotation. The bottom wall 1b of the rotor 1
Is further provided integrally with a small diameter portion 1a, and a polygon mirror or the like is attached using this portion.

Further, as a specific embodiment, FIG. 2 shows an example of a polygon mirror rotation driving device to which the present invention is applied.
This polygon mirror rotation driving device includes a polygon mirror 1
, A bottomed cylindrical rotor 1 that supports and rotates, and a hydrodynamic air bearing 13 that accommodates the rotor 1 and
And a cylindrical bearing member 12 constituting the bearing member 12.
A center pole 15 which is disposed at the center of the bearing member 14 and supports the stator coil 14; a base member 16 which supports the center pole 15 and closes the bottom of the bearing member 12;
The motor 17 mainly includes a stator coil 14 fixed to the side and a rotor magnet 3 fixed to the rotor 1 side.

In order to prevent the position of the center of gravity of the entire rotating system including the polygon mirror 11 from being shifted from the center axis of the rotor due to a machining error or an attachment error when the polygon mirror 11 is attached to the rotor 1, balance adjustment is performed. A balance plate 18 is attached. The balance plate 18 is formed in a disc shape by, for example, aluminum or a synthetic resin, and is provided so as to adjust a rotational balance by piercing a hole or the like (not shown) for a balance adjustment on a peripheral edge thereof as necessary. Have been. An air hole 19 is formed in the balance plate 18 at a position near the center of rotation. This air hole 19 communicates the inner space of the rotor and the outer space which are substantially sealed between the bearing member 12 and
It functions as an air damper.

The bearing member 12 is formed of aluminum or an aluminum alloy, and a bearing surface 12f is subjected to a surface treatment for improving abrasion resistance, and a central portion thereof is formed with an outer peripheral surface _1fo of the rotor 1. An annular peripheral groove 20 for supplying air to a dynamic pressure air bearing 13 formed between the air bearings is provided, and an air hole 2 opened outside the bearing member 12, for example, on an upper end surface.
1 to introduce air into the bearing surfaces 12f, _1fo .

On the inner peripheral surface 1 _fi of the large cylindrical portion of the rotor 1, a cylindrical yoke 2 is interposed and a cylindrical rotor magnet 3 is interposed.
Has been fixed. The rotor 1 is a bottomed cylinder formed of aluminum or aluminum alloy, the two annular grooves 7,7 formed in the bottom wall 1b side of the inner peripheral surface thereof 1 _fi inside (the bottom wall 1b nearer The FG magnet yoke 4, the FG magnet 5, the spacer 6, and the rotor magnet yoke 2 are fixed by the adhesive 8 applied to the fixing region 9 of the (part). The FG magnet 5 is fixed to the FG magnet yoke 4. The rotor magnet yoke 2 is adhered to the rotor 1 only in the fixing region 9, and is not fixed in the non-fixing region 10.

The rotor 1 has a polygonal mirror 11 mounted on a small cylindrical portion 1a protruding out of the bearing member 12, and is pressed by a wave spring 22 and a mirror retainer 23 to support the polygon mirror 11 on the bottom wall 1b. It is provided in. Grooves (not shown) for generating dynamic pressure are formed on the bearing surface _1fo of the large cylinder accommodated in the bearing member 12 to a depth of about 5 μm to 20 μm by, for example, etching or the like. The bearing surface _1fo of the rotor 1 is also subjected to a surface treatment for improving wear resistance.

A stator core 24 is fitted on the outer peripheral surface of the center pole 15, and a stator coil 1 is placed between non-magnetic coil plates 25 fitted on the stator core 24.
4 are wound. A circuit board for a frequency generator is installed at a position near the upper end of the center pole 15, and is arranged to face the FG magnet 5 for frequency generation on the rotor 1 side. A coil pattern is formed on the circuit board 26, and the FG magnet 5 rotates together with the rotor 1 to generate a rotation speed signal. Further, the base member 16
Below the rotor 1, the power supply to the stator coil 5 is controlled to
A driving circuit board 27 for rotationally driving the substrate is disposed.

A pair of ring-shaped magnets 28 and 29 constituting a thrust magnetic bearing 30 are fixed to the center pole 15 on the stator side and the rotor 1 so as to face each other. These magnets 28 and 29 are magnetized in the axial direction so that the surfaces facing each other become poles that attract each other, and are provided so that the entire rotor 1 is levitated by the attractive force in the axial direction.

[0020]

As is apparent from the above description, the motor according to the present invention has a structure in which a drive magnet or a drive magnet yoke or the like is adhered to the inside of a bottomed cylindrical rotor. One or several annular grooves are provided in the circumferential direction near the wall, and an adhesive is applied to a region near the bottom wall from the groove to fix necessary components such as a drive magnet yoke. However, even if a force acting to deform the rotor due to shrinkage during curing of the adhesive acts, the force is generated only in the vicinity of the bottom reinforced by the bottom wall, so that the rotor is not deformed and the accuracy of the rotor (true (Circularity, squareness) do not deteriorate. Accordingly, it is possible to manufacture a rotor having an extremely narrow bearing gap of several μm to several tens of μm between the rotor and the bearing member, and the product yield increases. Moreover, since the adhesive prevents the adhesive from flowing toward the relatively weak rotor opening by the annular groove, the adhesive is reliably stopped at the portion near the bottom wall, and the accuracy of the rotor can be sufficiently maintained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a rotor portion of the motor of the present invention.

FIG. 2 is a central longitudinal sectional view showing a polygon mirror rotation driving device as an example of the motor of the present invention.

FIG. 3 is a schematic view showing a rotor portion of a conventional motor.

[Explanation of symbols]

Reference Signs List 1 rotor 1b bottom wall of rotor 1 inner circumference noodle of _fi rotor 2 drive magnet yoke 3 drive magnet 4 FG magnet yoke 5 FG magnet 6 spacer 7 annular groove 8 adhesive

Claims (2)

(57) [Scope of request for utility model registration] A dynamic pressure bearing is formed between a bottomed cylindrical rotor whose one end is opened and the other end is partially or entirely closed by a bottom wall and a bearing member rotatably supporting the rotor. And a motor having a driving yoke and a driving magnet fixed to the inner surface of the rotor and further having a stator core and a stator coil disposed further inward, wherein one or more circumferential annular grooves are formed on the inner peripheral surface of the rotor. A motor, wherein a driving magnet, a yoke, and the like are fixed to the rotor by applying an adhesive to an inner side closer to the bottom than the groove. 2. The motor according to claim 1, wherein the rotor is formed of aluminum or an aluminum alloy.