JPH04124224U - Dynamic pressure gas bearing type rotating device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a hydrodynamic gas bearing type rotating device that can prevent contact between a rotating body and a base without increasing its size. [Configuration] A rotary body 7 disposed on the base 3, a shaft 11 fixed to one of the base 3 or the rotary body 7, and a shaft 11 fixed to the other of the base 3 or the rotary body 7. Bearing hole 7 that supports shaft 11
01, a driving means 9 for rotationally driving the rotating body 7, and a bearing hole 701 and a shaft 11 for sucking air when the rotating body 7 rotates.
In a hydrodynamic gas bearing rotating device equipped with an air suction groove 12 that forms an air film between The present invention is characterized in that magnetic thrust bearings 13 and 33 are disposed on the sides to repel each other.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to a dynamic pressure gas bearing type rotating device that rotatably supports polygon mirrors, etc. do.

0002

[Conventional technology]

For example, laser printers and facsimile machines have multiple reflective surfaces on their outer periphery. A polygon mirror is rotated at high speed, and its reflective surface emits a light beam corresponding to the image information. The light is reflected and scanned toward a light receiving means such as a photosensitive drum or CCD. Such polygon mirrors are generally rotatably supported by bearing devices. It is supported by a rotating body and rotates at high speed. As a bearing for such a polygon mirror, we replaced the conventional rolling bearing. Using gas bearings makes it possible to increase rotational speeds to tens of thousands of revolutions (rpm). This is advantageous in increasing printer speed and reading speed.

0003 Rotating devices using gas bearings have the movement of the rotating body itself sucking air as it rotates. A pressure gas bearing type rotation device and a static pressure gas bearing type rotation device that supplies air to the rotating part from the outside. However, dynamic pressure gas bearing type rotation equipment is less expensive than hydrostatic pressure gas bearing type rotation equipment. The device is more compact and lightweight because it does not require an air supply source such as a compressor. This is convenient for planning. A hydrodynamic gas bearing type rotating device generally includes a base and a base disposed on the base. a rotating body; a shaft fixed to one of the base or the rotating body; and a shaft fixed to the base or the rotating body; a bearing hole provided on the other side of the shaft for supporting the shaft, and a drive hand for rotationally driving the rotating body. a step formed in the shaft or bearing hole, which allows air to flow when the rotating body is rotated by the driving means; The shaft is equipped with an air suction groove that sucks air and forms an air film between the bearing hole and the shaft.

0004 In such a hydrodynamic gas bearing type rotating device, rotation occurs through the shaft, bearing hole, and air film. The rotating body is rotatably supported without contact with the base, but the rotating body and the base do not contact each other. Therefore, it becomes necessary to provide means for regulating the movement of the rotating body in the axial direction. Therefore, conventionally, as disclosed in Japanese Patent Application Laid-Open No. 2-304514, and flanges to form flanges facing each other, and these flanges to repel each other. An annular magnetic thrust bearing is embedded.

[0005]

[Problem that the idea aims to solve]

However, in such a structure, the flange for holding the magnetic thrust bearing is Since it is necessary to form a separate structure around the There was a problem. This invention was devised in view of the above circumstances, and the purpose of this invention is to We provide a dynamic pressure gas bearing type rotating device that can prevent contact between the rotating body and the base without causing any damage. There are many things.

[0006]

[Means to solve the problem]

In order to achieve the above object, the present invention includes a base, a rotating body disposed on the base, , a shaft fixed to one of the base or the rotating body, and a shaft fixed to the other of the base or the rotating body; a bearing hole for supporting the shaft; a driving means for rotationally driving the rotating body; It is formed in the shaft or bearing hole and sucks air when the rotating body is rotated by the driving means. Dynamic pressure gas bearing type equipped with an air suction groove that forms an air film between the bearing hole and the shaft. In a rotating device, the tip surface of the shaft and the base side location opposite to this tip surface or the rotation It is characterized by the fact that magnetic thrust bearings that repel each other are arranged on the body side parts. In addition, this invention has grooves for air flow formed on the surface of the magnetic thrust bearing. It is characterized by

[0007]

【Example】

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional front view of a dynamic pressure gas bearing type rotating device for a polygon mirror according to the first embodiment. Show the diagram. 1 is a dynamic pressure gas bearing type rotating device, and the rotating device 1 has a base 3 and a polygon mirror 5. It consists of a rotating body 7 to support, a motor 9 for rotating the rotating body 7, and the like.

[0008] A shaft 11 is erected non-rotatably from the base 3, and appropriate locations on the shaft 11 are indicated by diagonal lines. A spiral groove 12 is formed in this manner. The shaft 11 is inserted into the bearing hole 701 of the rotating body 7, and the rotating body 7 rotates with respect to the shaft 11. and axially movably coupled. On the upper end surface 1101 of the shaft 11 is a magnetic thrust bearing 13 made of a disk-shaped permanent magnet. is embedded with its upper surface 1301 exposed, and the upper surface 1 of this magnetic thrust bearing 13 is 301, as shown in FIG. 2, grooves 1303 for air flow are formed in a cross shape. There is. Note that this groove 1303 is formed as a concave portion with a V-shaped, rectangular, or semicircular cross section. be able to.

[0009] A coil 15 is housed around the shaft 11 on the upper surface of the base 3, and a coil 15 is housed on the top surface of the base 3. A substrate 17 is provided. The rotating body 7 includes a base member 19 in which a bearing hole 701 is formed, and a base member 1. 9 and the polygon mirror 5 are fixed to the base member 19. The presser member 23 and the flange 25 attached to the lower part of the base member 19 are Be prepared. A magnet 27 is attached to the flange 25 so as to face the coil 15. The coil 15 and the magnet 27 constitute a motor 9 (corresponding to a driving means). It is. The rotation of the rotating body 7 generates a rotating magnetic field by supplying current to the coil 15, which is This is done by acting on the magnet 27. As the rotating body 7 rotates, air is released from the spiral groove 12 formed in the shaft 11. - is supplied between the bearing hole 701 and the shaft 11, and this air film acts against the shaft 11. The rotating body 7 rotates at high speed (for example, 2 to 30,000 rpm) without contact.

0010 The upper member 21 has its outer peripheral portion attached to the upper end surface of the base member 19 with screws 31. The inner peripheral portion is fitted into the bearing hole 701. Further, the magnetic thrust bearing 1 is made of a disk-shaped permanent magnet on the lower surface of the inner circumference. A magnetic thrust bearing 33 that repels the magnetic thrust bearing 3 is embedded with its lower surface exposed. The presser member 23 has an upper surface portion attached to the upper member 21 with screws 35, and an outer periphery of the presser member 23. portion is fitted to the outer periphery of the base member 19 and the upper member 21, and the upper surface portion is fitted with a balance portion. A screw hole 2301 for attaching a weight is formed.

[0011] The polygon mirror 5 is fitted into the base member 19 and placed on the stepped portion of the base member 19. Then, it is incorporated into the rotating body 7. A ring plate made of an elastic material such as rubber is attached to the top surface of the ring plate. A shaped elastic member 37 is provided, and the polygon mirror 5 is held by the outer peripheral portion of the holding member It is pressed through the elastic member 37 and fixed onto the stepped portion of the base member 19 . The upper surface of the upper member 21 and the lower surface of the presser member 23 are arranged at a predetermined interval. , the upper surface of the upper member 21, the lower surface of the presser member 23, and the outer circumference of the presser member 23. A portion 41 is formed. The upper member 21 has a shape formed by the upper end surface 1101 of the shaft 11 and the lower surface of the upper member 21. A hole 45 is formed to communicate the space 43 and the space 41, and A hole 47 is formed in the upper surface of the holding member 23 so as to communicate the space 41 with the outside. is formed.

0012 In this embodiment, the upper end surface 1101 of the shaft 11 and the dead area above this upper end surface 1101 are Since the magnetic thrust bearings 13 and 33 are arranged using the space, the Compared to the conventional case of installing a flange for embedding a magnetic thrust bearing, the rotating device 1 is made larger. It becomes possible to prevent the rotating body 7 from coming into contact with the base 3 without molding. In addition, in the embodiment, a groove 1303 is formed on the surface of the magnetic thrust bearing 13 to prevent rotation. When the body rotates, the air between the magnetic thrust bearings 13 and 33 flows, and the holes 45 and the space 41, the air between the magnetic thrust bearings 13 and 33 is removed by external air through the hole 47. Since ventilation was provided, heat generation due to air friction between magnetic thrust bearings 13 and 33 This prevents galling and damage to the magnetic thrust bearings 13 and 33. This is advantageous in preventing. Note that the groove 1303 is connected to at least one of the magnetic slides. What is necessary is just to form it on the surface of the strike bearings 13 and 33.

[0013] Next, a second embodiment will be described with reference to FIG. In the second embodiment, the shaft 51 is fixed to the rotating body 7 and rotates together with the rotating body 7. This is different from the first embodiment. The same members and locations as in the first embodiment will be described with the same reference numerals. 7 consists of a base member 19, a flange 25, and a holding member 53, and the holding member 53 is It is attached to the upper end surface of the base member 19 and the upper end surface of the shaft 51 by screws 55 and 57. The Rigon mirror 5 is attached to the stepped portion of the base member 19 via the pressing member 53 and the elastic member 37. The polygon mirror 5 is fixed on the top of the rotating body 7, and the polygon mirror 5 is rotated together with the rotating body 7 by a motor 9. The lower part of the shaft 51 is rotatably and axially movable into the bearing hole 301 of the base 3. Spiral grooves 12 are formed at appropriate locations on the shaft 11 as shown by diagonal lines. ing. On the lower end surface of the shaft 51, a magnetic thrust bearing 61 made of a disk-shaped permanent magnet is located underneath. It is embedded with the surface 6101 exposed. As shown in FIG. 4, the lower surface 6101 of this magnetic thrust bearing 61 has air flow. A groove 6103 for use is formed in a curved shape from the center radially outward, and the shaft 51 is 4, rotate in the clockwise direction. Note that this groove 6103 has a V-shaped cross section and a rectangular shape. The shape can be formed with a semicircular recess.

[0014] A lower member 65 is attached to the lower part of the base 3, and the inner peripheral portion of the lower member 65 is connected to the bearing hole. 301, and a disk-shaped permanent magnet is attached to the upper surface of the inner peripheral portion of the magnet. A magnetic thrust bearing 67 that repulses the thrust bearing 61 is embedded with its upper surface exposed. It is rare. The upper surface of the lower member 65 and the lower end surface of the shaft 51 are arranged at a predetermined interval, and A space 69 is formed by the upper surface of the member 65, the bearing hole 301, and the lower end surface of the shaft 51. There is. The base 3 and the lower member 65 each have a structure that communicates the space 69 with the outside. Sea urchin holes 71 and 73 are formed.

[0015] According to the second embodiment, the lower end surface of the shaft 51 and the dead space below this lower end surface. Since the magnetic thrust bearings 61 and 67 are arranged using the As in the example, contact of the rotating body 7 with the base 3 is prevented without increasing the size of the rotating device 1. It becomes possible to do so. In addition, the groove 6103 allows the magnetic thrust bearings 61 and 67 to be connected when the rotating body rotates. The magnetic strip is caused to flow through the holes 71, spaces 69, and holes 73 by external air. Since the air between the last bearings 61 and 67 is ventilated, the magnetic thrust bearing 6 It can prevent temperature rise caused by heat generation due to air friction between 1 and 67, and magnetic thrust This is advantageous in preventing galling and damage to the bearings 61 and 67. Furthermore, the groove 6103 is It may be formed on the surface of at least one of the magnetic thrust bearings 61, 67.

[0016]

[Effect of the idea]

As is clear from the above explanation, according to the present invention, the tip surface of the shaft and the Since magnetic thrust bearings are installed using locations facing the It is possible to prevent contact between the rotating body and the base without increasing the size, and in addition, the magnetic thrust shaft By forming grooves on the surface of the bearing, heat generation due to air friction between the magnetic thrust bearings is reduced. In order to prevent the temperature rise caused by It is advantageous.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view of a rotating device according to a first embodiment.

FIG. 2 is a plan view of a magnetic thrust bearing.

FIG. 3 is a cross-sectional front view of a rotating device according to a second embodiment.

FIG. 4 is a plan view of the magnetic thrust bearing.

[Explanation of symbols]

1 Dynamic pressure gas bearing type rotating device 3 Base 5 Polygon mirror 7 Rotating body 11,51 axis 13, 33, 61, 67 Magnetic thrust bearing 1303,6103 Groove

Claims (2)

[Scope of utility model registration request] 1. A base, a rotating body disposed on the base, a shaft fixed to one of the base or the rotating body, and a shaft fixed to the other of the base or the rotating body. a bearing hole for supporting the shaft; a driving means for rotationally driving the rotating body; In a hydrodynamic gas bearing rotating device equipped with an air suction groove that forms an air film therebetween, the tip surface of the shaft and a portion on the base side or a portion on the rotating body opposite to this tip surface are repelled from each other. A hydrodynamic gas bearing rotating device characterized by being equipped with matching magnetic thrust bearings. 2. The dynamic pressure gas bearing type rotating device according to claim 1, wherein a groove for air flow is formed on the surface of the magnetic thrust bearing.