JPH04366013A - Dynamic pressure bearing device - Google Patents

Abstract

PURPOSE:To provide a dynamic pressure formed at the internal surface of a bearing for supporting a rotating shaft at low cost and efficiently, and also increase productivity and reliability of a bearing device. CONSTITUTION:An additional dynamic pressure due to deformation of plastic or oil-bearing plastics 2 and 4 is produced by the rotation of a rotating shaft 3 or a bearing 1 in addition to a conventional dynamic pressure. Thus a restoring force can be applied between the bearing 1 and the rotating shaft 3 in radial direction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing device that supports a rotating shaft by dynamic pressure generated inside the bearing.

0002

[Prior Art] Generally, a bearing device rotatably supports a rotating shaft inside the bearing, but in recent years, the inner circumferential surface of the bearing and the outer circumferential surface of the rotating shaft inserted inside the bearing have been Dynamic pressure bearing devices are being developed in which a dynamic pressure is generated by air or the like between the two, and a rotating shaft is supported by the supporting force of the dynamic pressure.

The bearing constituting this dynamic pressure bearing device is formed by forming a sleeve made of brass or iron-based material into the shape of, for example, a perfectly circular hollow cylinder. The rotary shaft is rotatably inserted with the handle. An annular groove is formed on the rotating shaft or the bearing by etching, rolling, cutting, etc., to stabilize the dynamic pressure and prevent the rotating shaft or the bearing from whirling around.

[0004] Furthermore, in this dynamic pressure bearing device, since a predetermined dynamic pressure cannot be obtained at the time of starting and stopping, the inner circumferential surface of the bearing and the outer circumferential surface of the rotating shaft may come into contact with each other. Therefore, damage is prevented by applying a wear-resistant material or plating to both or one of the rotating shaft and the bearing.

[0005]

However, in the conventional hydrodynamic bearing device, there is a problem in productivity because it is necessary to perform groove processing or apply wear-resistant material as described above. Furthermore, in order to generate dynamic pressure, the rotating shaft or bearings must be rotated at high speed, and therefore the drive motor must be highly rigid and highly accurate, which also increases costs. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydrodynamic bearing device that can obtain a good dynamic pressure for supporting a rotating shaft at low cost and improve productivity and reliability. shall be.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention creates a dynamic pressure between the inner circumferential surface of a bearing and a rotating shaft inserted into the bearing. The hydrodynamic bearing device rotatably supports the bearing, and has a structure in which a coating made of plastic or oil-impregnated plastic is formed on either the inner circumferential surface of the bearing or the outer circumferential surface of the rotating shaft. There is.

[0008]

[Operation] In a means configured as described above, dynamic pressure is generated due to minute irregularities on the surface due to the rotation of the rotating shaft or bearing, and this dynamic pressure causes deformation of the plastic or oil-impregnated plastic, causing a sawtooth wave-like expansion. A large number of protrusions are formed all around the circumference. The dynamic pressure generated by the bulging portion of the plastic or oil-containing plastic causes a restoring force in the radial direction to act between the bearing and the rotating shaft, resulting in continued quiet rotational movement. It has become.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the bearing 1 shown in FIGS. 1(a) and 1(b) is formed by forming a sleeve made of brass or iron-based material into a perfectly circular hollow cylinder shape. A coating 2 made of plastic or oil-impregnated plastic is molded over the entire circumference of the inner peripheral surface of the bearing 1. When the coating 2 is made of plastic, Teflon, polyacetal, nylon, etc. are used. On the other hand, oil-impregnated plastic is made by kneading several percent of lubricating oil into a plastic material, and when the coating 2 is formed of the oil-impregnated plastic, polyacetal, polyethylene, etc. are used as the plastic material. Plastics or oil-containing plastics constituting such a coating 2 include glass beads, carbon, molybdenum disulfide, and BN (
Fine particles such as boron nitride) can be mixed.

[0010] The molding thickness of the coating 2 is set to about several tens to hundreds of micrometers, but methods for molding a coating made of plastic or oil-impregnated plastic on the inner peripheral surface of the metal bearing base include, for example, There are methods of adhering the bearing base to plastic or oil-containing plastic using epoxy resin and drilling holes therein, and injection molding of the bearing base. There is also a method of pasting it on the inner peripheral surface, and a method of applying a material in the form of paint to the inner peripheral surface of the bearing base.

[0011] For the inner peripheral part of such a bearing 1,
A rotary shaft (not shown) is rotatably inserted into the coating 2 with a slight gap. At this time, the rotating shaft and the bearing 1 are each machined with high precision, and the clearance between the two is set to such an extent that the inner circumference of the bearing 1 and the outer circumference of the rotating shaft partially contact each other in a stationary state. .

In the second embodiment shown in FIGS. 2(a) and 2(b), a coating 4 made of plastic or oil-impregnated plastic is provided on the outer circumference of the rotating shaft 3 which is fitted into a bearing (not shown). Molded. This coating 4 is formed only on the bearing fitting portion, and its thickness is set to about several tens to several hundred μm, similar to the first embodiment.

Methods for molding the rotating shaft in this second embodiment include, for example, bonding the rotating shaft and plastic or oil-impregnated plastic using epoxy resin and subjecting this to centerless polishing; There are methods such as direct outsert molding.

[0014] Such a rotating shaft 3 is fitted into a bearing (not shown), but at that time, the coating 4 of the rotating shaft 3 is
and the inner peripheral part of the bearing are fitted so that there is a slight gap between them. That is, the rotating shaft 3 and the bearing are each machined with high precision, and the clearance between the two is set to such an extent that the inner circumferential portion of the bearing and the outer circumferential portion of the rotating shaft 3 partially contact each other in a stationary state.

In each of the embodiments shown in FIGS. 1 and 2, due to the relative rotation of the rotating shaft 3 or the bearing 1, there is a gap between the outer circumferential surface of the rotating shaft 3 and the inner circumferential surface of the bearing 1. Dynamic pressure is generated by pneumatic pressure or pneumatic pressure and hydraulic pressure. This dynamic pressure causes deformation of the coating 2 made of plastic or oil-impregnated plastic, as shown by the broken line in FIG. Ru. Dynamic pressure is further applied according to the bulging portion 5 of this plastic or oil-impregnated plastic. This additional dynamic pressure is similar to the dynamic pressure in a planar bearing as shown in FIG.

The dynamic pressure thus applied acts as a restoring force in the radial direction between the bearing 1 and the rotating shaft 3, thereby avoiding the so-called sliding gear motion that occurs in conventional bearing devices. This results in a quiet rotational movement. At this time, in each embodiment, since the clearance between the bearing 1 and the rotating shaft 3 is set small, a large original dynamic pressure is generated, and the plastic or oil-impregnated plastic is well deformed. A large additional dynamic pressure is also generated.

The dynamic pressure generated as described above is only air pressure (plastics) or both air pressure and hydraulic pressure (oil-impregnated plastics), and when starting and stopping rotation, the dynamic pressure is used as an auxiliary shaft support. It becomes power.

The reason why a thin layer of plastic or oil-impregnated plastic is applied to the inner circumferential surface of the bearing 1 and the outer circumferential surface of the rotating shaft 3 is to reduce changes in clearance due to temperature changes. Furthermore, plastics and oil-impregnated plastics do not have good heat dissipation properties, but because they are molded with a thin coating as mentioned above, and because the coating is molded on the metal bearing base, the heat generated by the sliding of the rotating shaft is is well dispersed. Therefore, the dimensions and shape of the coating do not change due to heat, and stable rotation can be obtained. Furthermore, in each of the above embodiments, since the bearing base is made of metal, good mechanical strength can be obtained.

Next, in the embodiment shown in FIG. 5, a plurality of locking grooves 6 are formed on the inner peripheral surface of the bearing 1, and each of these locking grooves 6 is filled with plastic or oil-impregnated plastic. By doing so, the plastic or oil-impregnated plastic is securely secured to the bearing 1. Alternatively, herringbone-shaped grooves may be formed on the surface of plastic or oil-impregnated plastic.

The present invention can be applied not only to journal bearings as in the above embodiments, but also to thrust bearings.

[0021]

As described above, the bearing device according to the present invention generates an additional dynamic pressure due to the deformation of plastic or oil-impregnated plastic in addition to the conventional dynamic pressure due to the rotation of the rotating shaft or the bearing. Since it is designed to apply a restoring force in the radial direction between the rotary shaft and the rotary shaft, a stable shaft support force can be obtained with a simple configuration without using grooves or wear-resistant materials. This makes it possible to improve the productivity and reliability of the bearing device.

[Brief explanation of drawings]

FIG. 1 is a front view and a side view showing a bearing device according to an embodiment of the present invention.

FIG. 2 is a front view and a side view showing a bearing device according to another embodiment of the present invention.

FIG. 3 is a partially enlarged cross-sectional view showing the principle of how dynamic pressure is generated.

FIG. 4 is a side view showing the principle of a planar dynamic pressure bearing device.

FIG. 5 is a front view showing a bearing device according to still another embodiment of the present invention.

[Explanation of symbols]

1 Bearing 2,4 Coating 3 Rotation axis

Claims (1)

[Claims] Claim 1: A dynamic pressure bearing device that rotatably supports the rotating shaft while forming dynamic pressure between the inner circumferential surface of the bearing and the outer circumferential surface of the rotating shaft inserted into the bearing. A hydrodynamic bearing device characterized in that a coating made of plastic or oil-impregnated plastic is molded on either the inner circumferential surface of the bearing or the outer circumferential surface of the rotating shaft.