JPH0550984U - motor - Google Patents

Abstract

(57) [Abstract] [Purpose] When fixing a magnet yoke, magnet, etc. to a cylindrical rotor by gluing, do not affect the roundness and squareness of the rotor. When a component such as a drive magnet 3 or a drive magnet yoke 2 is adhered to the inside of a bottomed cylindrical rotor 1, one or several annular members are provided near the rotor inner peripheral surface 1fi near the bottom wall 1b. Grooves 7 and 7 are provided in the circumferential direction, and an adhesive 8 is applied to a region 9 closer to the bottom wall than the grooves 7 and 7 to fix necessary components such as the drive magnet yoke 2 and the like. Even if a force to deform the rotor 1 acts due to the contraction, it is generated only near the bottom portion reinforced by the bottom wall 1b.
Therefore, the rotor 1 is not deformed, and the accuracy (roundness, squareness) of the rotor 1 is not deteriorated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a motor. More specifically, the present invention relates to a mounting structure of a rotor of a motor that rotates at high speed such as a laser scanning motor and a high-speed spindle motor, and a drive magnet and a yoke fixed to the rotor.

[0002]

[Prior Art]

 For motors that rotate at high speeds such as laser scanning motors, magnetic drum motors, gyro motors, or high-speed spindle motors, to support high-speed rotation, the rotor is supported by dynamic pressure air that accompanies rotation. A dynamic pressure air bearing is used. In this dynamic pressure air bearing, for example, a spiral dynamic pressure generating groove is formed on either of the outer peripheral surface of the rotor and the inner peripheral surface of a cylindrical bearing member that supports the rotor to form a rotor and the bearing. It is provided so as to be configured between the member. Since this dynamic pressure air bearing generates dynamic pressure during rotation to levitate and support the rotor, it has a very narrow fixed bearing gap between the rotor and the bearing member (although this is exaggerated in the figure). Usually, several μm to several tens of μm) are formed. Therefore, if a predetermined bearing gap cannot be accurately secured between the rotor and the bearing member, they contact and generate frictional heat, causing the so-called seizure phenomenon in which the shaft and the bearing adhere due to melting of the contact part. There is a risk of causing it. Therefore, sufficient circularity and squareness accuracy are required to manufacture rotors and bearing members.

On the other hand, in a high-speed rotation motor such as a laser scanning motor, a drive magnet yoke and a drive magnet are fixed inside a cylindrical rotor with an adhesive applied over the entire surface, and a stator is further provided inside thereof. It is considered that coils and iron cores are placed to make the motor compact and minimize the runout and tilt of the rotating shaft. In the case of a dynamic pressure air bearing with such a structure, the shape and structure of the rotating shaft becomes complicated, so rather than using hardened steel as the rotor material and grinding it, it is created by turning an aluminum alloy. Is much more advantageous in terms of processing cost. Therefore, it is desired that both the rotary shaft and the bearing member be made of aluminum or aluminum alloy.

[0004]

[Problems to be solved by the device]

 However, when the rotor is made of aluminum or an aluminum alloy, it is relatively soft and therefore deformed relatively easily by the action of an external force, so that there is a problem that the above bearing clearance cannot be maintained. That is, as shown in FIG. 3, in the prior art, the drive magnet yoke 102, the drive magnet 103, the FG magnet yoke 104, the FG magnet 105, and the spacer are formed on the inner peripheral wall surface of the aluminum cylindrical rotor 101. Each of 106 and the like is entirely bonded by an adhesive 107. For this reason, the force caused by the shrinkage of the adhesive during curing acts on the entire rotor area, deforming the rotor near the opening end where the strength is relatively weak, and affecting its accuracy (roundness and squareness). The product yield.

An object of the present invention is to provide a motor having a structure in which the accuracy of the rotor is not affected by adhering a magnet yoke or magnet to the rotor.

[0006]

[Means for Solving the Problems]

 In order to achieve such an object, the present invention provides a bottomed cylindrical rotor having one end opened and the other end partially or entirely closed by a bottom wall, and a bearing member rotatably supporting the rotor. A dynamic pressure bearing between the rotor, a drive yoke and a drive magnet fixed to the inner surface of the rotor, and a stator core and a stator coil disposed further inward, one or more on the inner peripheral surface of the rotor. An annular groove is provided in the circumferential direction, and an adhesive is applied to the inner side closer to the bottom than the groove to fix the drive magnet, the yoke and the like to the rotor.

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

[0008]

[Action]

 Therefore, even if a force to deform the rotor acts due to the contraction of the adhesive when it hardens, the rotor does not deform because it occurs only near the bottom portion reinforced by the bottom wall. Further, the partially applied adhesive is stopped by the annular groove in the circumferential direction and does not flow out to the portion near the opening end where it is easily deformed.

[0009]

【Example】

 Hereinafter, the configuration of the present invention will be described in detail based on the embodiments shown in the drawings.

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

An adhesive 8 is applied to the fixing region 9, and the FG magnet yoke 4, the FG magnet 5, the spacer 6 and the rotor magnet yoke 2 are fixed as necessary. The FG magnet 5 is fixed to the entire surface of the FG magnet yoke 4 with an adhesive 8. Further, a spacer 6 is fixed between the FG magnet 5 and the rotor 1. The spacer 6 serves to magnetically shield the FG magnet 5 and the rotor magnet 3 and is made of a non-magnetic material. An adhesive 8 is applied partially or entirely on the inner peripheral surface side of the rotor magnet yoke 2 to fix the rotor magnet 3.

Further, the rotor 1 has one end open, but the other end has a bottom wall 1b orthogonal to the cylindrical portion, and this portion provides a rib effect to resist deformation of the adhesive 8 due to contraction. It is provided to be. 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 on the inner peripheral surface of a cylindrical bearing member forming a dynamic pressure bearing with the rotor 1). Along with the rotation, a spiral groove is provided to support the bearing load by increasing the pressure of the fluid in the bearing gap, such as air, other gas, oil, or other liquid. A small-diameter portion 1a is integrally provided on the bottom wall 1b of the rotor 1, and a polygon mirror or the like is attached using this portion.

Further, as a concrete embodiment, FIG. 2 shows an example of a polygon mirror rotation driving device to which the present invention is applied. This polygon mirror rotation drive device has a cylindrical bottomed rotor 1 which supports a polygon mirror 11 and rotates, and a cylindrical air bearing 13 which houses the rotor 1 and forms a dynamic pressure air bearing 13 between the rotor 1 and the rotor 1. Bearing member 12, a center pole 15 that is arranged in the center of the bearing member 12 and supports the stator coil 14, a base member 16 that supports the center pole 15 and closes the bottom of the bearing member 12, and the bearing member 12 It is mainly composed of a motor 17 composed of a stator coil 14 fixed to the side and a rotor magnet 3 fixed to the side of the rotor 1.

In the rotor 1, balance adjustment is performed in order to prevent the center of gravity of the entire rotation system including the polygon mirror 11 from being displaced from the center axis of the rotor due to a processing error, an attachment error when the polygon mirror 11 is attached to the rotor 1, or the like. A balance plate 18 is attached for use. The balance plate 18 is made of, for example, aluminum or synthetic resin in a disk shape, and a hole for balance adjustment or the like (not shown) is formed in the peripheral edge thereof as needed to adjust the rotation balance. Is provided. The balance plate 18 has an air hole 19 formed at a position near the center of rotation. The air holes 19 connect the rotor inner space and the outer space, which are substantially sealed with the bearing member 12, to function as an air damper.

The bearing member 12 is made of aluminum or an aluminum alloy, the bearing surface 12f is subjected to surface treatment for improving wear resistance, and the outer peripheral surface 1 _fo of the rotor 1 is formed in the central portion thereof. An annular circumferential groove 20 for supplying air is provided to the dynamic pressure air bearing 13 formed between the air bearing 21 and the air from the air hole 21 opened at the upper end surface of the bearing member 12, for example, to the bearing surfaces 12f and _1fo . It is designed to be introduced.

A cylindrical rotor magnet 3 is fixed to the inner peripheral surface 1 _fi of the large cylindrical portion of the rotor 1 with a cylindrical yoke 2 interposed. The rotor 1 is a bottomed cylinder formed of aluminum or an A aluminum alloy, the inner (bottom wall 1b of the inner peripheral surface 1 _fi of the bottom wall 1 b of the two formed near the annular groove 7,7 that The FG magnet yoke 4, the FG magnet 5, the spacer 6 and the rotor magnet yoke 2 are fixed to each other by the adhesive 8 applied to the fixing area 9 in the (closer portion). 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 fixed region 9 and is not fixed in the non-fixed region 10.

Further, in the rotor 1, the polygon mirror 11 is attached to the small cylindrical portion 1 a protruding to the outside of the bearing member 12, and the polygonal mirror 11 is supported by the bottom wall 1 b by pressing the polygon mirror 11 with the wavy spring 22 and the mirror retainer 23. It is provided in. Grooves (not shown) for generating dynamic pressure are formed in the bearing surface 1 _fo of the large cylinder housed in the bearing member 12 to a depth of about 5 μm to 20 μm by, for example, etching. The bearing surface 1 _fo of the _rotor 1 is also surface-treated to improve wear resistance.

A stator core 24 is fitted on the outer peripheral surface of the center pole 15, and the stator coil 14 is wound between a non-magnetic coil plate 25 fitted on the stator core 24. A circuit board for a frequency generator is installed near the upper end of the center pole 15, and is opposed to the FG magnet 5 for frequency generation on the rotor 1 side. A coil pattern is formed on the circuit board 26, and a rotation speed signal is generated when the FG magnet 5 rotates together with the rotor 1. Further, below the base member 16, a drive circuit board 27 for controlling the energization of the stator coil 5 and rotationally driving the rotor 1 is arranged.

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

[0020]

[Effect of the device]

 As is apparent from the above description, the motor of the present invention is such that when a drive magnet or a drive magnet yoke is adhered to the inner portion of a cylindrical rotor with a bottom, the rotor inner peripheral surface near the bottom wall. Since one or several annular grooves are provided in the circumferential direction in the vicinity of, the adhesive is applied to the area closer to the bottom wall than this groove to fix the necessary parts such as the drive magnet yoke. However, even if the force that tries to deform the rotor due to shrinkage during curing of the adhesive acts, it occurs only near the bottom portion reinforced by the bottom wall, so the rotor does not deform and the accuracy of the rotor is improved. (Roundness, squareness) does not deteriorate. Therefore, 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, which increases the yield of products. Moreover, the adhesive prevents the adhesive from flowing out to the rotor opening side, which is relatively weak, so that the adhesive can be reliably stopped at the portion near the bottom wall and the rotor accuracy can be maintained sufficiently.

[Brief description of drawings]

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

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

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

[Explanation of symbols]

1 rotor 1b rotor bottom wall 1 _fi rotor inner circumferential noodle 2 drive magnet yoke 3 drive magnet 4 FG magnet yoke 5 FG magnet 6 spacer 7 annular groove 8 adhesive

Claims (2)

[Scope of utility model registration request] 1. A hydrodynamic bearing is constituted between a bottomed cylindrical rotor having one end opened and the other end partially or wholly closed by a bottom wall and a bearing member rotatably supporting the rotor. In a motor having a drive yoke and a drive magnet fixed to the inner surface of the rotor and a stator core and a stator coil disposed further inward, one or more circumferential annular grooves are formed on the inner surface of the rotor. A motor, wherein a motor is characterized in that a drive magnet, a yoke, etc. are fixed to the rotor by applying an adhesive on the inner side of the groove closer to the bottom than the groove. 2. The motor according to claim 1, wherein the rotor is made of aluminum or aluminum alloy.