JPS627407B2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) This invention includes a shaft body and an outer cylinder (sleeve),
Groove for generating dynamic pressure between the two members (dynamic pressure groove)
Regarding an improvement in an outer cylinder rotating type hydrodynamic compound bearing device, which is equipped with a thrust bearing part and a radial bearing part, and in which the outer cylinder rotates as the bearing part is lubricated with a lubricant such as oil or grease, In particular, the present invention provides a bearing device suitable for high-precision, high-speed rotation used in rotating parts of audio equipment such as VTRs.

(Prior Art) This type of hydrodynamic composite bearing device equipped with a thrust bearing section and a radial bearing section has been known for some time, for example, as disclosed in Japanese Patent Publication No. 46-8046 and Japanese Patent Application Laid-open No. 55-27551. It is publicly known.

However, in the case of the above conventional structure, the air inside the bearing repeatedly expands and contracts as the temperature around the bearing increases during use, the temperature of the bearing increases, and the temperature decreases during stoppage. Due to repeated changes in the internal pressure of the bearing, the lubricant in the bearing gradually leaks out to the outside, causing early damage to the bearing. At the same time, the bearing clearance due to the levitation force generated in the thrust bearing due to rotation is reduced. There was a problem in that it was difficult to maintain the thrust bearing at an appropriate value by adjusting the thrust bearing, and the outer cylinder rose more than necessary.

(Purpose) This invention solves the above-mentioned conventional problems, and its first purpose is to prevent lubricant from flowing out by preventing pressure changes inside the bearing when the bearing rotates and stops. The second purpose is to precisely adjust the flying height of the thrust bearing part, which has excellent durability, low torque and is suitable for high-speed rotation, and the height of the outer cylinder can be adjusted to the required height. The purpose of this invention is to obtain a hydrodynamic bearing device that is height balanced.

(Structure) That is, the present invention includes a shaft body and an outer cylinder having a bottom wall at one end that cooperates with the shaft body, and a thrust bearing portion is provided between the end of the shaft body and the bottom wall of the outer cylinder. A plurality of radial bearings are provided between the outer circumferential surface of the shaft body and the inner circumferential surface of the outer cylinder, and both of the bearing parts are connected to the outer cylinder through a pressure oil film of lubricant such as oil or grease. is rotatably supported, and an air vent hole is provided between the thrust bearing section and the radial bearing section and between the plurality of radial bearing sections, which communicates with the inside of the bearing and the outside air. The outer cylinder is attracted to the fixed shaft of the shaft body (on the side opposite to the thrust bearing part), thereby constantly communicating the inside of the bearing with the outside air, preventing changes in the internal pressure of the bearing, and thereby preventing lubricant from flowing out. At the same time, the height of the outer cylinder is balanced to the required height regardless of the levitation force generated in the thrust bearing.

(Example) Next, an example of an outer cylinder rotating type (shaft fixed type) of the dynamic pressure type composite bearing device of the present invention shown in the figure will be described. 1 is a shaft body, and 2 is an outer cylinder (also called a sleeve). , 3 is a thrust bearing portion, 4 is a radial bearing portion, 5 is an end plate serving as the bottom wall of the outer cylinder, 6 is a lubricant, and 7 is an air vent hole.

The shaft body 1 is fixed at one end (lower side when viewed from the drawing) or to a machine base (not shown), and has a hemispherical concave receiving surface 31 at the other end (upper side when viewed from the drawing). The concave receiving surface 31 is provided with an appropriate number of spiral grooves (dynamic pressure grooves) (not shown) for generating dynamic pressure. A flat part 13 is formed between the large diameter part 11 and the small diameter shaft part 12, and a flat part 13 is formed at a position slightly below the large diameter part 11 and further below the flat part 13 at an appropriate distance (at the lower end of the outer cylinder). For example, a herringbone groove (dynamic pressure groove) 1 as shown in the figure is provided in the small diameter portion 12 (near the area).
A radial bearing surface 14 having a diameter of 5 is provided.

The outer cylinder 2, which is fitted around the shaft body 1 and rotates, has an end plate 5 attached to its upper end, which serves as a bottom wall of the outer cylinder, and an inner end thereof has the concave receiving surface. A spherical convex receiving surface 32 is fixed to the convex receiving surface 31 and works opposite to the concave receiving surface 31 and the convex receiving surface 32.
A lubricant is sealed between the radial bearing surface 14 and the inner circumferential surface 23 of the outer cylinder facing the outer cylinder. Two radial bearing portions 4, 4 are formed.

In the above embodiment, the inclined portion 51 of the thrust bearing portion at a position connected to the convex bearing surface 32 faces the inclined surface 16 connected to the concave bearing surface 31 with a slight gap, and the thrust bearing portion 3 It constitutes the sealing part for the lubricant in. Further, on the upper end side of the outer cylinder 2, a pocket plane 22 is formed which faces the pocket hole 21 into which the large diameter part 11 of the end of the shaft body is inserted and the plane part 13 with a desired gap. , has a structure that prevents the outer cylinder 2 from separating from the shaft body 1.

Inner peripheral surface 2 of the hole provided in the center of the outer cylinder 2
3, the inner circumferential surfaces 23, 23 that face and share the radial receiving surfaces 14, 14 provided on the outer circumference of the small diameter shaft portion 12 have a larger diameter than the inner circumferential surface 23, and the shaft body A space 24 is formed between the outer circumferential surface and the outer circumferential surface.

Furthermore, air vent holes 7, 7 are opened in the pocket 21 and the space 24 of the outer cylinder 2, respectively, and communicate with the outside air outside the outer cylinder 2. In other words, air vent holes 7 are formed between the thrust bearing 3 and the radial bearing portion 4 (upper side as viewed from the drawing) and between the radial bearing portions 4, 4, which communicate the inside and outside of the bearing. has been done.

In addition, the outer cylinder 2 in the bearing device is designed to prevent the outer cylinder 2 from floating more than necessary due to the dynamic pressure generated in the thrust bearing (to prevent the axial clearance of the thrust bearing 3 from becoming larger than necessary), and to In order to stabilize the shaft body 1 in a certain direction, the outer cylinder 2 is attracted to the fixed side of the shaft body 1 by the magnetic force of a drive motor (not shown) directly connected to the device.

In this case, as a matter of course, the rotor of the drive motor is fixed to the outer cylinder 1 side, and the stator is fixed to the shaft body 1 side.

Oil or grease is used as a lubricant for each of the bearings, but in order to reduce rotational torque, it is preferable to use oil with low viscosity.In that case, use oil with high surface tension to lubricate the bearing clearance. It is necessary to improve the retention of Furthermore, although the thrust bearing portion in the embodiment is spherical, it is of course possible to have a planar shape without any problem. Further, in the embodiment, an example in which the outer cylinder rotates and the shaft body is fixed has been described, but the reverse may be possible depending on the equipment used.

(Operation and Effect) As described above, in the hydrodynamic type composite bearing device of the present invention, there are a plurality of radial bearing portions that are combined with the thrust bearing portion and are arranged at intervals in the axial direction. , it goes without saying that the rotating side member is prevented from collapsing or whirling around during rotation, resulting in smooth rotation without uneven rotation, and especially between the thrust bearing section and the radial bearing section and between multiple radial bearing sections. Each of the bearings is constructed with an air vent hole that communicates with the outside air inside and outside the bearing, so that the internal temperature of the bearing due to temperature changes around the bearing and changes in the temperature of the bearing caused by rotation or stoppage of the bearing. This prevents repeated internal pressure changes due to air expansion and contraction, and as a result, lubricant leakage from the radial bearing due to internal pressure changes is effectively prevented, and there is almost no damage to the bearing due to insufficient lubrication. Not only can a bearing device with excellent durability be obtained, but also when assembling the shaft and the outer cylinder pre-filled with lubricant, due to the relationship with the air vent hole, the pushing pressure during assembly will not be applied. Therefore, the lubricant inside the outer cylinder can be kept to a minimum from leaking out (outflowing) from the inlet portion (the side opposite to the bottom wall).

Further, while the bearing device is rotating, the outer cylinder is attracted to the fixed side of the shaft body by a certain magnetic force, for example, the magnetic force of a drive motor directly connected to the bearing device, so that a thrust force is generated in the thrust bearing portion. A constant appropriate clearance between the end of the shaft and the bottom wall of the outer cylinder can be maintained regardless of the magnitude of the dynamic pressure, and therefore the flying height of the outer cylinder can be maintained. It is possible to hold the thrust load constant, stabilize the thrust load in a certain direction, and balance the height to a desired value.

In the embodiment, the flat surface 13 of the large diameter portion 11 of the shaft body
and the plane 2 of the pocket hole of the outer cylinder facing this
Although 2 is a simple flat surface, it can also be provided with a groove for generating dynamic pressure to function as a thrust bearing.

In addition, in order to facilitate assembly and processing of the device, the large diameter portion 11 and small diameter portion 12 of the shaft body are made separate.
It may be fixed with adhesive or the like during assembly.

Furthermore, a groove for generating dynamic pressure (dynamic pressure groove) may also be formed in the outer cylinder, or may be formed in both the shaft body and the outer cylinder.

Further, although the embodiment is shown in a rigid shape, it may also be used in a horizontal shape.

Furthermore, the shape of the dynamic pressure groove formed in the bearing, the type of lubricant used, the position and shape of the air vent hole, etc. may be changed as appropriate within the scope of the claims.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the hydrodynamic composite bearing device of the present invention. In the symbols of the embodiment, 1 is a shaft body, 2 is an outer cylinder, 3 is a thrust bearing portion, 4 is a radial bearing portion, and 7 is an air vent hole.

Claims (1)

[Scope of Claims] 1. A shaft body whose one end is fixed to the machine base, and an outer cylinder having a cylindrical hole with a bottom wall at one end surrounding the shaft body, the other end of the shaft body and the outer cylinder A dynamic pressure type thrust bearing is provided between the bottom wall of the shaft and a radial bearing between the outer circumferential surface of the shaft and the inner circumferential surface of the outer cylinder. In an outer cylinder rotating type hydrodynamic compound bearing device in which the outer cylinder rotates while being lubricated with a lubricant such as grease, there is a desired space between the outer circumferential surface of the shaft body and the inner circumferential surface of the outer cylinder in the axial direction. a plurality of radial bearing parts spaced apart from each other, an air vent hole communicating between the inside of the bearing and the outside air between the thrust bearing part and the radial bearing part and between the plurality of radial bearing parts, and . An outer cylinder rotating type dynamic pressure composite bearing device, characterized in that the outer cylinder is attracted toward a fixed side of the shaft body by magnetic force. 2. In the hydrodynamic composite bearing device according to claim 1, the hydrodynamic grooves forming the thrust bearing portion are located on the end surface of the shaft body, and the hydrodynamic grooves forming the radial bearing portion are located on the outer circumferential surface of the shaft body. External rotary type hydrodynamic compound bearing device. 3. The external cylinder rotating type hydrodynamic composite bearing device according to claim 1 or 2, wherein an air vent hole is formed in the external cylinder. 4. In the external cylinder rotating type hydrodynamic composite bearing device according to any one of claims 1 to 3, the attractive force due to the magnetic force is fixed to the stator fixed to the shaft body and the external cylinder. An outer cylinder rotating type hydrodynamic compound bearing device which is driven by a drive motor consisting of a rotor with a rotor. 5. The outer cylinder rotating type hydrodynamic composite bearing device according to any one of claims 1 to 4, further comprising separation prevention means for preventing the shaft body and the outer cylinder from being separated from each other. A rotating external cylinder type hydrodynamic compound bearing device.