JPS58134217A - Dynamic pressure gas bearing device for rotary unit - Google Patents

Abstract

PURPOSE:To reduce the starting torque by adopting a dynamic pressure gas bearing for improving the dynamic revolution precision, the reliability in high speed, and the durability and shaping the end face of a thrust bearing into a convex spherical face. CONSTITUTION:When a sleeve 3 is rotated, the surrounding gas is led as an arrow A shows by the operation of a dynamic pressure generating groove 111, and introduced between an outer diameter face 11 of a fixed shaft 1 forming a radial bearing and a sleeve inner diameter face 32 of a sleeve main body 31. Furthermore, this gas is exhausted to the open air through a shaft hole 34 via a pressure chamber 10 shaped between a thrust end face 12 of the fixed shaft 1 and a thrust end face 33 of the sleeve 3 for forming a thrust bearing. The thrust end face 33 of the sleeve 3 is shaped into a convex spherical face for reducing the starting torque and the damage at the stoppage of starting.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a bearing device used in rotating units such as office machines, electronic equipment, information equipment, and optical equipment.

Conventionally, bearing devices for rotating units of rotating polygon mirror light polarizers used in this type of equipment, such as lasers, mirrors, and printers, have often had a structure in which ball bearings are used to support both ends of the shaft on which the polygon mirror is attached. It is being In such a rotating polygon mirror light polarizer, the rotation accuracy of the polygon mirror during high-speed rotation is poor.
・If there is uneven rotation, the printed characters will be blurred, so the dynamic rotation precision required of the support bearing is extremely strict. Moreover, as printers have become faster and smaller, the number of rotations of a rotating polygonal polarizer has increased to several thousand r.
The speed has recently increased from pl to tens of thousands of rps, and the equipment itself is also becoming smaller. Therefore, in a spindle device using a conventional ball bearing, there are vibrations caused by shape errors in the machining of the bearing ring of the ball bearing, vibrations caused by the ball thread mK, vibrations caused by the cage, or vibrations contained in the ball bearing. 1' is required because uneven rotation caused by wood grease being irregularly bitten by the rotating ball cannot be avoided.

It is becoming difficult to satisfy rotational accuracy and rotational unevenness. Additionally, as speeds increase, the lifespan of ball bearings has become shorter, creating problems in terms of reliability. Furthermore, in order to prevent the polygon mirror from getting dirty, the support bearing is
It is desirable not to use lubricants such as grease that may evaporate. However, since ball bearings are lubricated with grease, performance deterioration of the polygon mirror due to grease scattering and evaporation is unavoidable. Further, even if a magnetic fluid seal is used, scattering and evaporation of the oil used in the magnetic fluid cannot be avoided, and this cannot be an essential countermeasure. In addition, in the case of ball bearings, preload adjustment is required, so assembly is not necessarily easy, and in order to maintain dynamic rotation accuracy, it is difficult to assemble without mounting errors, which increases production costs. Damn it, I scolded you.

In order to improve the above-mentioned drawbacks, the present invention aims to improve dynamic rotation accuracy, high-speed reliability, and durability, and uses a hydrodynamic gas bearing that can keep the area around the bearing clean. The drawback is that the starting torque is large,
It is an object of the present invention to provide a rotary unit circumferential gas bearing device which is easy to cause damage during start-up and stop, and which is improved, has a simple bearing structure, is easy to assemble, and is excellent in mass production.

The present invention will be explained as an example based on FIG. 1. A groove l11 for generating dynamic pressure is provided in the outer diameter surface 11 of the fixed shaft l fixedly installed on the base 2, and the sleeve 3 equipped with the polygon mirror 4 is driven by the rotor 5, as shown in FIG. When viewed from above and rotated clockwise, the surrounding gas moves in the direction of the arrow due to the action of the dynamic pressure generating groove 111.
It flows between the outer diameter surface 11 forming the radial bearing and the slot → γ inner diameter surface support of the sleeve body 31. Sara K this episode 1III! One-C, Jiaya bearing. The inflowing air passes through the pressure chamber 10 formed between the thrust end surface 12 on the non-fixed side of the identification shaft and the thrust end surface of the slim nib 3 that cooperates with the thrust end surface 12, and passes through the sleeve body 31 which communicates with the surrounding outside air.
It flows out through a shaft hole provided in a separate thrust bearing part 35, forming a thrust bearing. Therefore, when the sleeve 3 is stationary and rotates at low speed, the thrust end surface of the sleeve 3 is in contact with the thrust end surface 12 of the fixed shaft 1, but during rotation, the thrust surface formed by the air flowing out as the sleeve 3 rotates. The thrust end face is supported by a gas bearing membrane. The thrust end face 12 and at least one of the end faces are formed into a convex spherical surface in order to reduce starting torque and reduce damage during starting and stopping.

In addition, -1: In order to reduce the starting torque and reduce damage during starting and stopping, it is more effective to form a shaft hole on the end face that forms the convex spherical surface because it prevents the convex spherical surface from digging into the shaft hole. . Furthermore, one end surface may be a convex spherical surface, and the other cooperating end surface may be a concave spherical surface having a slightly larger radius than the convex spherical surface. In this embodiment, in order to reduce the starting torque at the end face of the sleeve 3 when starting the sleeve 3, and to improve the wear resistance when starting and stopping, the end face is made of plastic with good sliding properties. Alternatively, the thrust bearing part may be constructed integrally with the sleeve body, although the thrust bearing part is made of a material such as ceramic with good wear resistance and is attached separately from the main body 31 of the sleeve 3.

Further, a material such as plastic or ceramic may be used for the end face of the thrust end face 12 of the fixed shaft. The stator 6 of the drive motor is fixed to the housing 7 and serves as a cover to prevent damage. Therefore, this bearing device is sealed with the base 2, the housing 7, and the cover 8.

Next, as another example, as shown in Fig. 2, in order to reduce the load on the thrust bearing when the rotating part is placed internally and the thrust end face is worn during startup and stop, the rotating part is supported by suction with an auxiliary thrust magnetic bearing. This shows what was done. The structure of the auxiliary thrust magnetic bearing 9 can be simplified if a permanent magnet is used for at least one of the magnetic members 91 and 92. However, both 91 and 92 may be opposed using permanent magnets, or
You can use a permanent magnet 92K tri-magnetic body for 1, as in 1 degree or more, this rotation 3-knit dynamic pressure gas bearing □:
1. In the device, the rotating three-shield has a radial gas (air) bearing section consisting of a dynamic pressure group bearing formed by the outer diameter surface of the fixed shaft and the inner diameter surface of the sleeve cooperating with it in the radial direction, and the radial gas (air) bearing part in the axial direction. The thrust gas (air) bearing section is supported in a non-contact manner by the thrust gas (air) bearing section, which is formed by a gas film produced by the action of the dynamic pressure groove of the radial gas bearing section. Therefore, the rotating sleeve is not in contact with the hydrodynamic gas bearing membrane, so
In addition to avoiding uneven rotation caused by bearings, by using group bearings for the radial bearings, a preload effect from dynamic pressure acts on the radial square, making it possible to keep the radial runout of the sleeve to an extremely small level even at high speed rotation. In addition, in this bearing device, the thrust bearing section utilizes the gas flowing out from the radial bearing section due to the dynamic pressure effect, and the gas flowing out from the shaft hole that opens approximately in the center of the thrust end face 12 and either end face. Since the thrust load capacity is generated by squeezing K, the structure is extremely simple and advantageous in terms of cost.

Moreover, even if abrasion powder is generated when the thrust end faces come into contact with □ and □ during startup and stop, it is discharged to the outside of the bearing through the shaft hole, which prevents the abrasion powder from accelerating the wear of the end faces. In addition, since either the end surface 12 or the blade of the thrust bearing end face is formed into a convex spherical surface, the starting torque, which is a disadvantage of hydrodynamic gas bearings, is significantly reduced. It has the advantage of being able to reduce wear due to contact during startup and stop.In addition, as a hydrodynamic gas bearing, the radial bearing part and thrust bearing part are integrally constructed. Since the sleeve of the rotating part can be supported by a cantilevered fixed shaft with one end fixed to the base, structural compliance is improved.
It is possible to provide a bearing device that is simple and not affected by assembly accuracy, and is advantageous in terms of cost and accuracy. In addition, although the rotor and stator parts that make up the drive motor tend to generate heat, due to the action of dynamic pressure, a gas flow is formed that flows in through the bearing clearance of the radial bearing part and flows out through the shaft hole that opens in the thrust bearing part. Therefore, there is an advantage that the gas flow for cooling the cylinder can be automatically generated.

Note that, since the grooves for generating dynamic pressure provided in the radial bearing portion are designed according to the conditions of use, groove patterns other than those shown in the embodiments may be used.

As can be seen from the above embodiments, when the hydrodynamic gas bearing device for a rotating unit of the present invention is used, the rotational accuracy is good, there is no rotational unevenness, it is suitable for high-speed rotation, the starting torque is small, and the thrust Good wear resistance on the bearing end face, no contamination around the bearing from lubricants such as grease and oil and sealing fluid (%), assembly accuracy with a force of 1 and assembly volume of 4', and excellent mass production. A rotating unit is obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a diagram corresponding to FIG. 1 of another embodiment, where 1 is a fixed shaft, 2 is a base, and 3
is the sleeve, 12, μs is the thrust end face, oblique is the shaft hole, 1
11 is a miso paste for generating dynamic pressure. Patent applicant NSK Ltd.! 2F Procedural amendment (voluntary) June 16, 1980 q# Age Agency Director Haruki Shimada 1, Indication of the case 1982 Patent Application No. 16299 3, Person making the amendment Relationship with the case Patent applicant 4, In column 5 of "Detailed Description of the Invention" of the specification to be amended, on page 2, lines 19-2D of the specification of contents of the amendment, the phrase ``laser, mirror, printer'' is corrected to ``laser beam printer.'' Procedural amendment (voluntary) July 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office1, Indication of the case Patent Application No. 16299 of 19833, Person making the amendment Relationship to the case Patent applicant 4, Subject of the amendment (1) "Claims" column of the specification (2) Contents of the amendment in "Detailed Description of the Invention" column 5 of the specification (1) Addendum to the "Claims" column of the specification Correct as expected. (2) Column ``Detailed Description of the Invention'' in the specification a) On page 7, lines 7-8 of the specification, it says, ``The scale interval of the rotating part is...''. "..." I corrected myself. Page 8 of the specification, lines 9 to 15: "In addition, in this bearing device, the thrust bearing section utilizes the gas flowing out from the radial shaft section due to the dynamic pressure effect, and the thrust end surface 12 and either one of the Since the thrust load capacity is generated by squeezing the gas flowing out from the shaft hole that opens approximately at the center of the end face, the structure is extremely simple and is advantageous in terms of cost. In this bearing device, the thrust bearing part utilizes the gas generated by the dynamic pressure effect in the radial bearing part a, that is, the gas from the radial bearing part is transferred to both thrust end faces 12.
, the thrust load capacity is generated, and the flow is made to flow into the shaft hole opening in the center of the thrust end face 12 and either end face, so the structure is extremely simple and cost effective. It's advantageous. ” he corrected. C) In the first line of page 9 of the specification, the phrase "...because it is formed on a convex spherical surface" has been replaced with "...when it is formed on a convex spherical surface," I am corrected. -,. [Attachment] Claim (1) In a rotation unit having a structure in which a sleeve rotates around a cantilevered fixed shaft whose one end is fixed to a base, the inner diameter surface and/or the inner rear surface of the sleeve and A groove for generating dynamic pressure is provided on the outer diameter surface of the cooperating fixed shaft, and a shaft hole that opens at the center of the fixed shaft or the thrust end surface of the sleeve Q and communicates with the outside air is provided. The working gas generated by the groove for generating dynamic pressure is introduced into the pressure chamber formed between the thrust end faces, and the pressure in the pressure chamber is adjusted by the shaft hole to support the sleeve. Features of dynamic pressure gas bearing device for rotating unit. A hydrodynamic gas bearing device for a rotating unit according to claim 1, wherein a thrust magnetic bearing is provided. (4) The hydrodynamic gas bearing device for a rotating unit according to claim 1, wherein either one of the thrust end faces is made of plastic or ceramic with good shearing properties. (5) The rotation unit according to claim 1, comprising a hydrodynamic gas bearing, wherein the shape of the groove for generating dynamic pressure includes a groove shape that causes a pressure increase at least toward the thrust end face. Dynamic pressure gas bearing device. (6) The rotating unit circumferential dynamic pressure gas bearing device according to claim 1, wherein the gas bearing device is sealed with a sealing member such as a base and a nozzle.

Claims (5)

[Claims] (1) A cantilever fixed shaft with one end fixed to the base, and a groove for generating dynamic pressure on the outer diameter surface of the fixed shaft cooperating with the fixed shaft, and a thrust end face on the opposite side of the fixed shaft or / and a thrust end surface of the sleeve that cooperates with the end surface is formed into a convex spherical surface, and the fixed shaft or the sleeve is provided with a shaft hole that opens at the center of the thrust end surface and communicates with the outside air, and the Working gas generated from the groove K for generating dynamic pressure is introduced into a pressure chamber formed between both thrust end faces, and the π force of the pressure chamber is adjusted by the shaft hole to support the sleeve. Dynamic pressure gas bearing device for rotating unit. (2) The hydrodynamic gas bearing device for a rotating unit according to claim 1, wherein one auxiliary thrust magnetic bearing is disposed between the rotating sleeve and the base. (3) The hydrodynamic gas bearing device for a rotating unit according to claim 1, wherein either one of the thrust end faces is made of plastic or ceramic with good shearing properties. (4) The recirculation unit according to claim 1, comprising a hydrodynamic gas bearing whose shape includes a groove shape that causes a pressure increase at least toward the thrust end face. Dynamic pressure gas bearing device. (5) The gas bearing device for a rotary unit according to claim 1, wherein the gas bearing device is sealed with a sealing member such as a base and a housing.