JPS62228710A - Bearing device - Google Patents

Abstract

PURPOSE:To shorten axial dimension and obtain a compact bearing device by arranging a magnetic thrust bearing between an axial direction end of a rotary member fitted around a fixed shaft and a housing. CONSTITUTION:An upper end part in axial direction of a fixed shaft 22 is press-fit, glued and fixed into a fixed shaft supporting member 22b of a housing 20. On the peripheral surface of the fixed shaft 22 are arranged radial bearing surfaces 23 and 24 provided with dynamic pressure generating grooves 23a and 24a in herringbone shape. Further, around the lower end is rotatably fitted a hollow-shaped rotary member 32 supported with a magnetic thrust bearing. As a thrust receiving surface 44 side of a thrust receiver 40 on the rotary member 32 side is magnetized to the N pole and a thrust bearing surface 46 side of a thrust bearing 45 on the housing 20 side is also magnetized to the N pole, the thrust bearing supports the rotary member in a levitated condition by means of magnetic repulsive force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bearing device used in a rotating mechanism of an office machine, video equipment, audio equipment, etc.

[Conventional technology]

As a conventional bearing device of this type, for example, a bearing device used in an optical deflector shown in FIG. 2 is known. This optical deflector includes a housing 1 having a laser beam transmission window 2.
The lower end of the fixed shaft 3 in the axial direction is fixed to the fixed shaft 3, and a rotating member 5 to which the optical deflector 4 is attached is rotatably fitted around the fixed shaft 3.

Herringbone-shaped grooves 6a and 6b effective for supporting radial loads are formed at both ends of the fixed shaft 3 in the axial direction, and grooves 6a and 6b effective for supporting thrust loads are formed in the middle part of the fixed shaft 3 in the axial direction. A spiral groove 7 is formed.

Among the axial ends of the rotating member 5, the lower end on the fixed end side of the fixed shaft 3 is an open end, and the upper end on the opposite side has an exhaust hole 8 for thrust pressure adjustment in the axial direction. A thrust receiver 9 penetrating through the shaft receiver 9 is fitted, and its bottom surface 9a faces the axially upper end surface 3a of the fixed shaft 3.

A rotor 10 of a drive motor is attached to the outer circumferential surface of the rotating member 5, and a stator 12 disposed opposite to the outer circumferential surface of the rotor IO is attached to the housing 1, so that the rotating member 5 is rotated around the fixed shaft 30. ing.

When the rotating member 5 rotates, the groove 6b in the lower end of the fixed shaft 3
Dynamic pressure is generated due to the pumping action of the rotary member 5, and the air that flows into the radial bearing gap 15 between the lower end side of the rotating member 5 and the fixed shaft 3 rises due to the pumping action of the groove 7 in the intermediate portion. The air overcomes the dynamic pressure in the groove 6a on the upper end side and rises further, reaching the exhaust hole 8 of the thrust receiver 9.
leaks to the outside. As a result, the rotating member 5 rotates around the fixed shaft 3 while maintaining a non-contact state due to the high-pressure air film formed in the gap between the rotary member 5 and the fixed shaft 3, and the bottom surface 9a of the thrust receiver 9 rotates around the fixed shaft 3. Axial upper end surface 3 of 3
It levitates from a and maintains a non-contact state also in the axial direction.

[Problem that the invention seeks to solve]

In the above-mentioned conventional bearing device, the radial bearing gap 15 between the rotating member 5 and the fixed shaft 3 is filled with air by the grooves 5a, 6b at both axial ends of the fixed shaft 3 and the groove 7 at the intermediate part. A film is formed, and a complete non-contact state is maintained in the radial direction between the rotating member 5 and the fixed shaft 3.Therefore, there is no problem with the radial load capacity, but the bottom surface of the thrust receiver 9 of the rotating member 5 In order to obtain the necessary and sufficient thrust load capacity to maintain a non-contact state in the axial direction between 9a and the axial upper end surface 3a of the fixed shaft 3, it is necessary to It is necessary to increase the length in the axial direction to a certain extent, and in order to obtain thrust load capacity by the dynamic pressure generated in the groove 7 in the intermediate portion, the length in the axial direction of the fixed shaft 3 must be shortened to a certain limit or less. Since this is not possible, there is a problem in that the axial length of the rotating member 5 increases accordingly.

Further, in the conventional bearing device, as described above, the bottom surface 9a of the thrust bearing 9 of the rotating member 5 is opposed to the axially upper end surface 3a of the fixed shaft 3. Therefore, when starting and stopping the rotating member 5, the axial upper end surface 3a of the fixed shaft 3 and the rotating member 3
This results in sliding contact with the bottom surface 9a of the thrust receiver 9 without lubrication, which results in an increase in frictional torque, and the sliding contact surface between the fixed shaft 3 and the rotating member 5 is easily worn out, reducing durability. There is a problem with the decline.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a bearing device in which the fixed shaft and rotating member have short axial length dimensions and are highly durable.

[Means for solving problems]

In the bearing device of the present invention, one axial end of a fixed shaft is fixed to the housing, and a rotating member having an open end on the fixed end side of the fixed shaft is rotatably fitted around the fixed shaft through a radial bearing gap. equipped.

The radial bearing surface of the fixed shaft and the radial bearing surface of the rotating member are formed with a groove for generating dynamic pressure on one side, and the rotating member is moved in the radial direction by a fluid film in the radial bearing gap between the fixed shaft and the rotating member. A dynamic pressure type radial fluid bearing is installed to support the system.

At the end of the rotating member opposite to the open end and the housing, a thrust receiver and a thrust bearing made of magnets are arranged to face each other, so that the magnetic poles on the thrust receiving surface side and the thrust bearing surface side are the same magnetic pole. A thrust magnetic bearing is installed to support the rotating member in the axial direction by the magnetic repulsion force in the thrust bearing gap between the thrust bearing surface and the thrust bearing surface.

[Effect]

In the bearing device of the present invention, when the rotating member rotates around the fixed shaft, the pumping action of the groove for generating dynamic pressure formed on at least one of the radial bearing surface of the fixed shaft and the radial bearing surface of the rotating member is applied. Dynamic pressure is generated, and a fluid film formed by the fluid flowing between the open end of the rotating member and the fixed shaft is formed in the radial bearing gap, increasing the pressure, and the rotating member is supported in the radial direction by the pressure of this fluid film. and rotates around a fixed axis in a non-contact manner.

In addition, a magnetic repulsion force by the magnet acts in the thrust bearing gap between the thrust bearing at the axial end opposite to the open end of the rotating member and the thrust bearing in the housing facing this, and the rotating member Since it is supported in the axial direction in the floating position, both ends in the axial direction rotate while maintaining a non-contact state with respect to the housing.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment in which the bearing device of the present invention is applied to the optical deflector shown in FIG. 2.

In the figure, the housing 20 includes a cylindrical side wall member 2
A fixed shaft support member 2 is provided on the upper end side and the lower end side of 0a, respectively.
0b and the thrust bearing mounting member 20C are fitted and sealed to prevent dust and other foreign matter from entering from the outside, and the inside of the housing 20 is filled with gas such as air.

The upper end portion of the fixed shaft 22 in the axial direction is fixed to the fixed shaft support member 20b of the housing 20 by press fitting, adhesive, or shrink fit. The outer circumferential surface of the fixed shaft 22 has two cylindrical radial bearing surfaces 23 , an upper end and a lower end in the axial direction.
24, and herringbone-shaped grooves 23a and 24a for generating dynamic pressure are formed in the radial bearing surfaces 23 and 24, respectively, with the fletching tips facing in the same direction.

A hollow rotary member 32 whose lower end is supported by a thrust magnetic bearing, which will be described later, is rotatably fitted onto the outer periphery of the fixed shaft 22.

The rotating member 32 has two axially cylindrical radial bearing surfaces 33 and 34 that contact the radial bearing surface 2.3 of the fixed shaft 22 via gas in the radial bearing gap 35 between the rotating member 32 and the fixed shaft 22, respectively. .24 and the cono radial bearing surface 23
．． 24 and the radial bearing surfaces 33 and 34 constitute a dynamic pressure type radial air integral bearing that supports the rotating member 32 in the radial direction around the fixed shaft 22.

In this way, radial bearing surfaces 23.
4 and the radial receiving surfaces 33 and 34, the rotating member 3
2. Runout during rotation is reduced, and stable high-speed rotation performance is obtained.

The fixed shaft 22 and the rotating member 32 are preferably made of a non-magnetic material that is less susceptible to the effects of thrust magnetic bearings.

Among the axial ends of the rotating member 32, the upper end on the fixed end side of the fixed shaft 22 is an open end, and the thrust receiver 40 is fitted to the lower end on the opposite side. This thrust receiver 40 has a metal ring 43 on the outer periphery and the lower side, and a magnetic permanent magnet 41 with plastic on the inner periphery and upper and lower sides integrally molded and fixed to the metal ring 43,
The lower end surface of the permanent magnet 41 is a flat thrust receiving surface 44.

Further, the thrust bearing mounting member 20c of the housing 20 has a thrust bearing 45 mounted at a position facing the lower end of the rotating member 32. This thrust bearing 45 is also made of a magnetic permanent magnet made of plastic, and has a flat thrust bearing surface 46 on its upper end surface.

The thrust receiver 40 on the rotating member 32 side has a thrust receiving surface 44
The side of the thrust bearing 45 on the housing 20 side is similarly magnetized as a north pole, and the thrust bearing surface 46 side of the thrust bearing 45 on the housing 20 side is similarly magnetized as a north pole. The thrust magnetic bearing is supported in the axial direction in a floating state by a magnetic repulsion force acting on the thrust bearing gap 48 between the receiving surface 44 and the thrust bearing surface 46.

As described above, the thrust receiver 40 of the rotating member 32 has a magnetic body made of plastic fixed to the metal ring 43 on the outer peripheral side by integral molding, so that when the rotating member 32 rotates at high speed, centrifugal force The material of this metal ring 43, which will not be damaged even when subjected to a large force due to
It is preferable to use steel, especially hardened stainless steel.

Note that the hole 42 that passes through the thrust receiver 40 of the rotating member 32 in the axial direction is provided for exhaust to facilitate the work when inserting and assembling the fixed shaft 22 into the rotating member 32.

In a state where the rotating member 32 is axially supported by the thrust magnetic bearing and maintained in the floating position, an axially intermediate portion is maintained between the upper end surface of the thrust receiver 40 and the lower end surface of the fixed shaft 22. That's how it is. This axial distance A is set to be larger than the axial curvature interval between the open end surface of the rotating member 32 and the inner surface of the fixed shaft support member 20b of the housing 20, and Even if an abnormality occurs in the floating position, the thrust receiver 40 is prevented from contacting the lower end surface of the fixed shaft 22, and the thrust receiver 4
This prevents the magnet 0 and the lower end surface of the fixed shaft z2 from remaining in contact with each other.

As a rotational drive mechanism for the rotating member 32, a rotor 50 is attached to a stepped portion of the outer circumferential surface of the lower end side, the lower surface of which is supported and fixed by a ring member 53, and a stator 52 is opposed to the outer circumferential side of the rotor 50 with a cylindrical surface. is attached to the abutment 21 of the housing 20.

Further, an optical deflection mirror 55 is attached to the flange 37 at the axially intermediate portion of the rotating member 32, and the ring member 55 is attached from the upper end side.
6 is clamped and fixed. A laser beam is incident on the optical deflection mirror 55 from a light source (not shown), and the laser beam reflected by the optical deflection mirror 55 passes through the transmission window 58 of the side wall member 20a of the housing 20 and hits an external photoreceptor (not shown). It is now irradiated.

Further, an annular recess 54 is provided on the lower surface of the ring member 53 that fixes the rotor 50, and an annular recess 57 is similarly provided on the upper surface of the ring member 56 that fixes the optical deflection mirror 55. Recesses 54, 5 of these ring members 53, 56
7, the mass of the rotating member 32 is adjusted and the unbalance in the radial direction is corrected by applying an appropriate amount of adhesive or the like as necessary.

In the embodiment, the radial bearing surface 2 of the fixed shaft 22
Herringbone-shaped grooves 23a and 24a are formed at 3.24, and this groove 23a.

24a may be formed on the radial bearing surface 33.34 of the rotating member 32, or may be formed on both the radial bearing surfaces 23, 24 and the radial bearing surface 33.34.

In addition, the permanent magnets constituting the thrust magnetic bearing can be mass-produced and manufactured at low cost by using a magnetic material with plastic as in the above embodiment. It is also possible to use sintered magnets made of powder compacts such as elements.

Further, in the drive motor of the rotating member 32, a disk-shaped rotor is attached to the rotating member instead of the cylindrical rotor 50 and stator 52 of the above embodiment, and the stator is attached to the housing with a plane facing the lower surface of the rotor. You can also do that.

In this case, since the suction force of the stator acts on the rotor and the wobbling of the rotating member 32 during rotation can be reduced, it is also possible to use the bearing device horizontally.

Further, although the housing in the above embodiment is completely sealed by the constituent members of the housing, an indirect sealing structure may be used in which the gas inside the housing is communicated with the outside air through a filter. Furthermore, when the housing is partially opened, the entire device in which the housing is installed may have a sealed structure.

In addition, in the above embodiment, a case was explained in which a gas such as air is sealed in the housing, but the bearing device of the present invention is not limited to the above embodiment. The present invention can also be applied to devices that use radial bearings as hydrodynamic bearings.

〔Effect of the invention〕

As explained above, the bearing device of the present invention includes a thrust magnetic bearing between the axial end of the rotating member fitted around the fixed shaft and the housing to support the rotating member in the axial direction. Therefore, the radial bearing surface and radial bearing surface that make up a radial fluid bearing only need to have a load capacity that supports only radial loads. There is no need to provide Therefore, according to the present invention, the axial length dimensions of the fixed shaft and the rotating member can be shortened compared to the conventional bearing device, and a bearing device that is compact and easy to manufacture can be obtained.

Further, according to the present invention, since the rotating member is supported in the axial direction in a constantly floating state by the magnetic repulsion of the thrust magnetic bearing, even when the rotating member is started and stopped, both end faces in the axial direction Since there is no sliding contact with the housing, not only the friction torque is reduced, but also the wear between the thrust bearing surfaces and the thrust bearing surfaces is reduced, so that a bearing device with excellent durability can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of a conventional bearing device. In the figure, 20 is a housing, 22 is a fixed shaft, 23° and 24 are radial bearing surfaces, 23a and 24a are grooves for generating dynamic pressure,
32 is a rotating member, 33, 34 is a radial bearing surface, 35 is a radial bearing clearance, 40 is a thrust bearing, 44 is a thrust bearing surface, 45 is a thrust shaft bearing, 46 is a thrust bearing surface,
48 is a thrust bearing clearance.

Claims (6)

[Claims] (1) One axial end of a fixed shaft is fixed to the housing, and a rotating member having an open end on the fixed end side of the fixed shaft is rotatably fitted around the fixed shaft through a radial bearing gap, and A groove for generating dynamic pressure is formed in at least one of the radial bearing surface of the fixed shaft and the radial bearing surface of the rotating member that face each other across the radial bearing gap, and the rotating member is moved in the radial direction by a fluid film within the radial bearing gap. A thrust bearing made of a magnet and a thrust bearing are installed facing each other at the axial end of the rotating member opposite to the open end and the housing, and the thrust bearing is supported by a dynamic pressure radial fluid bearing. The magnetic poles on the thrust bearing surface side of the bearing and the thrust bearing surface side of the thrust bearing are made the same magnetic pole, and the rotating member is supported in the axial direction by the magnetic repulsion force in the thrust bearing gap between the thrust bearing surface and the thrust bearing surface. A bearing device comprising a thrust magnetic bearing. (2) The axial distance between the axial end surface of the fixed shaft opposite to the fixed end and the thrust receiver of the rotating member is set larger than the axial distance between the open end of the rotating member and the housing. A bearing device according to claim 1. (3) The bearing device according to claim 1 or 2, wherein a ring member provided with a recess for adhering a mass adjustment material in a radial direction is attached to the rotating member. (4) The bearing device according to any one of claims 1 to 3, wherein the fixed shaft and the rotating member each have a radial bearing surface and a radial bearing surface at two locations in the axial direction. . (5) The bearing device according to any one of claims 1 to 4, wherein the thrust bearing of the rotating member and the thrust bearing of the housing are permanent magnets made of magnetic material made of plastic. (6) The bearing device according to claim 5, wherein the thrust bearing of the rotating member includes a metal ring on the outer peripheral side and a magnetic body made of plastic integrally molded and fixed to the metal ring.