JPS6358283B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spindle unit that is equipped with an outer cylinder and a shaft body, and in which either one of them rotates. The present invention relates to a hydrodynamic spindle unit having a hydrodynamic bearing part that is effective as a spindle unit used in micro motors, audio equipment, and the like.

Rolling bearings and oil-impregnated sliding bearings have been used in the bearings of conventional spindle units of this type, but these are not sufficient in terms of acoustics, vibration, torque, etc. The performance of the equipment was unstable and there were also problems from the point of view of energy conservation, so improvements in the bearings were particularly desired.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks and problems.

The basic structure of the present invention is that the outer cylinder has a circular hole, and a thrust receiving member that closes the circular hole is attached to one axial end of the outer cylinder. The circular hole has radial bearing surfaces constituting a radial bearing portion at two locations separated in the axial direction, and the thrust bearing member has a thrust bearing surface constituting a thrust bearing portion. A mounting member is attached to the shaft inserted into the circular hole by fitting into the end opposite to the thrust receiving member, and the shaft has a radial outer surface facing the radial receiving surface and a thrust receiving surface facing the thrust receiving surface. It has an outer surface. Both the radial bearing portion and the thrust bearing portion have dynamic pressure generating grooves, and the number of dynamic pressure generating grooves in the radial bearing portion on the mounting member side is equal to the number of dynamic pressure generating grooves in the radial bearing portion on the thrust bearing member side. is more than. Regarding the clearance between the outer cylinder and the shaft body, the radial clearance between the two radial bearing parts is larger than the radial clearance between the radial bearing parts. The outer cylinder is provided with an air vent hole that communicates between the two radial bearing parts and the outside,
Further, the diameter of the shaft body is approximately equal to that of the portion to which the attachment member is attached and the radial outer surface.

Next, the present invention will be explained with reference to the embodiments shown in FIGS. 1 and 2. 1 is an outer cylinder, 2 is a shaft body, 3 is a rotational drive mechanism for the shaft body 2, 4 is a stator held in the outer cylinder, 5 14 is a mounting member which is a body holding the rotor 6, and 14 is an elastic O which elastically supports the thrust receiving member 12 and seals between it and the other member.
It's a ring.

Introduction In the first embodiment shown in FIG. 1, an outer cylinder 1 has a circular hole 11 at its axial center position into which a shaft body 2 is inserted, and at both ends separated in the axial direction,
It has radial bearing surfaces 111 and 112 that form a radial bearing part in cooperation with the outer peripheral surface of the shaft body 2, which will be described later. At one end of the circular hole 11 (lower side in the drawing), a thrust receiving member 12 having a hemispherically concave thrust receiving surface 121 is attached to the presser plate 1.
3, the thrust receiving member 12 is held through the circular hole 11 and closes the circular hole 11. The circular hole has a larger diameter than the radial receiving surfaces 111, 112 at the point between the two radial receiving surfaces 111, 112, and the outer diameter at the point between the upper radial receiving surface 111 and the lower radial receiving surface 112. Radial clearance between cylinder 1 and shaft 2
t ₁ is formed larger than the bearing clearance t ₂ of the radial bearing portion. In this case, the shaft body side may be made smaller in diameter.

Further, the radial clearance between the radial bearing part and the thrust bearing part is made larger than the radial clearance of the radial bearing part to reduce the viscosity resistance of the lubricant.

The shaft body 2 has a radial receiving surface 111,1 of the outer cylinder.
The radial outer surfaces 22 and 23 have multiple herringbone-shaped dynamic pressure generating grooves 21 on the outer circumferential surface at two locations facing the radial outer surface 12, and a plurality of spiral-shaped grooves are provided on one shaft end (on the thrust receiving member side). It has a hemispherical thrust outer surface 24 with a groove 241. In particular, in this embodiment, the diameter of the thrust outer surface 24 is set in consideration of ease of assembly.
Although the diameter is smaller than that of No. 3, there is no effect on performance whether the diameter is the same or larger.

The radial bearing portion and the thrust bearing portion are filled with a lubricant necessary to form a pressure fluid layer.

With the above structure, for example, when the shaft body 2 rotates as in the embodiment, a levitation force is generated in the thrust bearing section, causing the shaft body 2 to float, and at the same time, pressure in the radial direction is applied to the radial bearing section. As a result, the shaft body 2 is rotatably supported by the outer cylinder 1 without contacting it. A mounting member 5 is fitted to the end opposite to the thrust receiving member 12 and attached to the shaft body 2, and the shaft body 2 has a portion where the mounting member 5 is attached and a radial outer surface 22, 23.
and have approximately the same diameter.

FIG. 2 shows that the outer cylinder 1 is composed of an outer cylinder member and a sleeve 15 fitted and attached to the inner diameter surface of the outer cylinder member.
2,153. sleeve 15
radial bearing surfaces 111 and 112 are formed on the outer cylinder 1, and an air vent hole 16 is provided in the outer cylinder 1 to communicate between the two radial bearing parts and the outside. The air vent hole 16 prevents lubricant from leaking to the outside between the outer cylinder 1 and the shaft body 2 due to the expansion of the air between the outer cylinder and the shaft body due to temperature changes in the surrounding air. Helps prevent.

In addition, since the radial clearance t ₂ between the two radial bearing parts is both very small, if the outer cylinder 1 does not have the air vent hole 16, when the shaft body 2 is inserted into the radial bearing surface 111 on the opening side, it will form a circular shape. It is difficult to insert the shaft body 2 into the circular hole 11 due to the resistance of fluid such as lubricant in the hole 11 being pushed out from the radial bearing clearance on the opening side. In particular, when inserting the shaft body into the radial bearing surface 112 on the thrust receiving member 12 side, the shaft body 2 is inserted into the radial bearing surface 112 at two locations.
Since the axial length of the portion facing 1 and 112 is long, the resistance of the fluid in the lower part of the circular hole to be pushed outward through the two radial bearing gaps becomes large, and the thrust bearing member of the shaft body 2 It is very difficult to insert it into the radial receiving surface 112 on the 12 side.

In this invention, the outer cylinder 1 has an air vent hole 1 that communicates between the two radial bearing parts and the outside.
6, so the shaft body 2 is attached to the radial bearing surface 11 on the opening side.
Since the fluid between the two radial bearing parts inserted into the shaft body 1 flows out from the air vent hole 16, the shaft body 2 is smoothly inserted into the radial bearing surface 111 on the opening side. The shaft body 2 is connected to the thrust receiving member 1
When the shaft body 2 is inserted into the radial bearing surface 112 on the opening side, the fluid between the two radial bearing parts is not pushed out through the radial bearing clearance on the opening side, and the shaft body 2 is inserted into the radial bearing surface 112 on the opening side. Receiving surface 11
1, it moves smoothly in the axial direction. In addition, the shaft body 2 has a radial bearing surface 11 on the side of the thrust bearing member 12.
Since the axial length of the portion facing the circular hole 11 is not long, the fluid in the bottom of the circular hole 11 flows into the thrust receiving member 1.
Air vent hole 1 through the radial bearing clearance on the 2 side
The resistance to being pushed out in the direction 6 is not so large, and the shaft body 2 can be easily inserted into the radial receiving surface 112 on the thrust receiving member 12 side.

In addition, in order to prevent lubricant from leaking to the outside from the radial bearing clearance on the opening side when the shaft body 2 rotates, the number of dynamic pressure generating grooves 21 in the radial bearing portion on the mounting member 5 side is adjusted to The number is greater than the number of dynamic pressure generating grooves 21 in the radial bearing section on the 12 side. Therefore, the retention of the lubricant within the radial bearing clearance on the opening side is improved, which helps to prevent unstable vibrations, that is, whirl, of the shaft body 2 due to lack of lubricant. Note that as the sleeve 15, an oil-impregnated porous member such as metal or plastic impregnated with oil may be used.

In addition, if the load is large, it is necessary to use a high viscosity grease or oil, but if a high viscosity lubricant is used, the friction torque of the radial bearing will increase at low temperatures, which may limit the operating temperature range. . In such a case, by incorporating a temperature-controllable heater into the radial bearing, the viscosity of the lubricant can be maintained at an optimum level, and the torque at low temperatures can be kept low.

In addition, in order to completely eliminate the friction torque at the radial clearance t ₁ between the two radial bearing parts, it is necessary to prevent the lubricant from getting into the clearance t ₁ part, and to It is effective to add a lubricant such as oil with high tension. Particularly when a seal body is not used, it is desirable to use oil with high surface tension to improve oil retention in the bearing portion.

Furthermore, if the load on one side of the bearing, for example, the radial load is small and the thrust load is large, it is recommended to use a lubricant with high viscosity on the thrust bearing.
Conversely, it is desirable to use a lubricant with low viscosity for the radial bearing. In this case, in order to avoid mixing of the two types of lubricants, it is preferable to provide a seal between the two bearings.

In the embodiment, the dynamic pressure generating grooves are provided on the shaft body side, but they may be provided on the outer cylinder side, or may be provided on both surfaces.

In addition, the detailed structure of each bearing, bearing formation, the shape of the dynamic pressure generating groove, the design specifications of the bearing, the presence or absence of a seal body,
The position where it is used, the lubricant used, etc. may be changed as appropriate within the scope of the claims.

Furthermore, even when the shaft body, which is one of the members forming the bearing part, is formed by cutting from a single member, considering production volume, usage conditions, etc., the shaft part and the thrust outer surface 24 may be separated. In some cases, a member having a part is made separately and then integrally joined.

Furthermore, although a spherical thrust bearing is used as the thrust bearing in the embodiment, a conical shape, a cylindrical shape, an oval shape, a planar shape, etc. may be used, and the shape is not particularly limited.

As mentioned above, in the spindle unit of the present invention, all the bearing parts are hydrodynamic bearings, so there is less noise, vibration, and torque unevenness during rotation, and since it can rotate with a small torque, there is no noise, vibration, By using it in equipment that dislikes large torque, it is possible to significantly improve the performance of that equipment.

Furthermore, since the number of dynamic pressure generation grooves 21 in the radial bearing part on the mounting member 5 side is greater than the number of dynamic pressure generation grooves 21 in the radial bearing part on the thrust bearing member 12 side, the radial bearing clearance on the opening side is leaked to the outside. This prevents lubricant from leaking and improves lubricant retention within the radial bearing clearance on the opening side.

Also, the clearance between the outer cylinder 1 and the shaft body 2 is the radial clearance t ₁ between the two radial bearing parts.
is larger than the radial clearance _t2 of the radial bearing, the viscous resistance of the lubricant during rotation is significantly reduced, and the friction torque of the spindle as a whole can be significantly reduced. Therefore, it is particularly effective as a rotating spindle for micro motors, audio equipment, etc. Furthermore, since the outer cylinder 1 is provided with an air vent hole 16 that communicates between the two radial bearing parts and the outside, the air between the outer cylinder 1 and the shaft body 2 is kept at the temperature of the surrounding air. Leakage of the lubricant to the outside from between the outer cylinder 1 and the shaft body 2 due to expansion due to change is prevented, and insertion into the circular hole 11 of the shaft body 2 is easy. Furthermore, since the shaft body 2 has approximately the same diameter as the portion where the mounting member 5 is attached and the radial outer surfaces 22 and 23, the shaft body 2
It is easy to process the portion to which the mounting member 5 is attached and the radial outer surfaces 22, 23, and the cost is low. In addition, since the part of the shaft body 2 where the mounting member 5 is attached is not a stepped small diameter part, the shaft body 2
It is easy to ensure the strength and bending rigidity of the portion to which the mounting member 5 is attached.

In addition, in the case of rotation of the shaft body 2, a rotor 6 is arranged on the outer periphery of the stator 4 attached to the outer peripheral surface of the outer cylinder 1, and this rotor 6 is attached to the shaft body 2 via the mounting member 5. The outer diameter of the member 5 increases.

Therefore, since a large centrifugal force acts on the shaft 2, the swing of the shaft 2 is large. However, in the case of rotation of the outer cylinder 1, since the outer diameter of the rotor attached to the outer peripheral surface of the outer cylinder 1 is small, the centrifugal force acting on the outer cylinder is small, and the swing of the outer cylinder is small.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views showing a hydrodynamic spindle unit of the present invention, with FIG. 1 showing a first embodiment and FIG. 2 showing a second embodiment. In the figure, 1 is an outer cylinder, 2 is a shaft body, 5 is a mounting member, 11 is a circular hole, 111, 112 are radial bearing surfaces, 12 is a thrust bearing member, 121 is a thrust bearing surface, 16 is an air vent hole, 21 , 241 is the dynamic pressure generation groove, 24 is the thrust outer surface, 22 and 23 are the radial outer surfaces, t ₁ is the radial clearance between the two radial bearings, and t ₂ is the radial clearance between the radial bearings. .

Claims (1)

[Scope of Claims] 1. The outer cylinder has a circular hole, a thrust receiving member that closes the circular hole is attached to one end in the axial direction of the outer cylinder, and the circular hole has two axially spaced apart holes. The thrust bearing member has a radial bearing surface constituting a radial bearing part, and the shaft body inserted into the circular hole has a radial bearing surface constituting a radial bearing part. In a spindle unit in which a mounting member is fitted and attached to an end portion, and the shaft body has a radial outer surface facing the radial bearing surface and a thrust outer surface facing the thrust bearing surface, the radial bearing portion and the thrust bearing portion are connected to each other. are both equipped with dynamic pressure generating grooves, and the number of dynamic pressure generating grooves in the radial bearing portion on the mounting member side is greater than the number of dynamic pressure generating grooves in the radial bearing portion on the thrust bearing member side, and the outer cylinder and shaft body The radial clearance between the two radial bearing parts is larger than the radial clearance of the radial bearing part, and the outer cylinder has a space between the two radial bearing parts and the outside. 1. A dynamic pressure type spindle unit, characterized in that a communicating air vent hole is provided, and a portion of the shaft body to which a mounting member is attached and a radial outer surface thereof have approximately the same diameter. 2 Claim 1 in which the outer cylinder rotates during operation
Dynamic pressure type spindle unit as described in .