JPS61241519A - Dynamic pressure type fluid bearing - Google Patents

Abstract

PURPOSE:To prevent flowing of a lubricant by pressing and fixing a thrust member in a hole communicating with a bearing hole, and disposing a space between a dynamic pressure generating groove of a shaft and a spiral groove of a thrust member, and an air hole connecting the space to the outside. CONSTITUTION:A cut groove 3B extending in the axial direction is disposed on the outer periphery of a thrust member 3. A space 2F not keeping a lubricant is provided between a dynamic pressure generating groove 1B and a spiral groove 3A. A connecting hole 3B communicating with the air is disposed in the space 2F. In this arrangement, even if the ambient temperature rises due to heat generated by a motor or pressure is decreased in the inside of a plane, air bubbles mixed in lubricants 4A-4C are quickly discharged from vent holes 2C, 2B, and the air bubbles are expanded to keep the lubricants from being pushed away from a bearing gap.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a dynamic pressure fluid bearing in the thrust direction used in video tape recorders and the like.

2. Description of the Related Art A conventional hydrodynamic bearing of this type has dynamic pressure generating grooves 11A and 11B in a bearing hole 12A, as shown in FIG.
The lower part of the bearing hole 12A is machined straight with the same diameter as the bearing hole, and a cylindrical thrust member 13 having a groove 1sA is press-fitted and fixed therein. . Here, the dynamic pressure generating groove 11A
There is a lubricant 14B near the dynamic pressure generating groove 11B.
14A of lubricant is held near the spiral groove 13A, and the shaft 11 is rotated by the fixed side motor member 17 and the rotating side motor member 18, and the amount of lubricant is 11A.

11B, floating due to the pumping action of the groove 1sA, 3.

Rotates without contact. 12 is a lower cylinder, 12B is a sleeve, 12C is a ventilation hole, 15 is a disk, and 16 is an upper cylinder.

Problems to be Solved by the Invention However, in a hydrodynamic bearing of the above structure, as shown in FIG. expands as shown at 19 in the figure, causing the lubricant 14A to flow out of the bearing as shown at 140, causing the bearing to wear due to lack of oil.

Furthermore, this type of hydrodynamic bearing was published in 1986-166.
As shown in No. 51, a low viscosity oil with good temperature characteristics and low frictional torque is used in the dynamic pressure generating grooves 11A and 11B of the shaft 11 that constitute the radial bearing, and two different types of lubricants are sometimes used. However, in this structure, the dynamic pressure generating groove 1
1B and the spiral groove 13A were close to each other, and the lubricants between the grooves were mixed, making it impossible to obtain the desired performance.

Means for Solving the Problems In order to solve the above problems, the hydrodynamic bearing of the present invention has a hole coaxially formed below the bearing hole that communicates with the bearing hole, and a spiral groove is formed in this hole. A thrust member having the bearing is press-fitted, a space is provided between the dynamic pressure generating groove on the shaft side and a spiral groove on the thrust member side, and a ventilation hole is provided to communicate the space with the outside of the bearing.

Effects The present invention has the above-described configuration, so that even if different lubricants are applied to the dynamic pressure generating groove on the shaft side of the radial bearing and the spiral groove on the thrust bearing side, there is no space between them. Because of this, there is no mixing.

That is, each lubricant is held separately in the narrow bearing gap by surface tension. In addition, even if there are small air bubbles in the lubricant, the air bubbles will be discharged from the ventilation holes, and there is no need to worry about them expanding and causing the lubricant to flow out, so it is highly reliable against changes in external temperature and pressure. .

EXAMPLE Hereinafter, a hydrodynamic bearing according to an example of the present invention will be described with reference to FIG. In Figure 1, 1 is the axis, 1A, q
B is a dynamic pressure generating groove for supporting radial load, 2A is a bearing hole, 2B is a sleeve, 2C is a ventilation hole, 2 is a lower cylinder, 6 is a disk, 6 is an upper cylinder, 7 is a fixed side motor member, 8 is a rotating side motor member, which is the same as the conventional example. 9A is a fixed rotary transformer, 9B is a rotating rotary transformer, and 9A and 9B work as a pair to transmit electrical signals. In addition, a hole 2E communicating with the bearing hole 2A is machined below the dynamic pressure generating groove 1B of the shaft 1,
A thrust member 3 having a spiral groove 3A on the upper surface is shown here.
is fixed by press fitting.

4A, 4B, and ac are lubricants held in the bearing gaps, and 4B is the lubricant 4A held in the spiral groove 3A that constitutes the thrust bearing, if necessary.

Lubricants other than 4C may also be used. Thrust member 3
As shown in 3B of FIG. 3, a groove extending in the axial direction is provided on the outer periphery of the shaft. Further, a space 2F which does not hold lubricant is provided between the dynamic pressure generating groove 1B and the spiral groove 3A. This space 2F is the bearing hole 2 on the inner diameter of the sleeve.
Either a part with a larger diameter than A is provided, or a part with a smaller diameter than the outer diameter of @1 is provided. Also, in this configuration, which is common to the conventional example, the hole 2E is machined at the same time as the bearing hole 2A, as shown in FIG. It is constructed so that the parallelism between the end face and the spiral group 3A can be maintained with high accuracy.

Also, by adjusting the pushing amount when press-fitting the thrust member 3, the system spiral group 3. Since the position in the height direction is adjustable, the structure is such that the relative position between the magnetic tape (not shown) and the upper cylinder 6 can be accurately assembled during assembly.

The operation of the fluid bearing constructed as described above will be explained. The fixed side motor member 7 is energized and the shaft 1 starts rotating together with the rotating side motor member 8.

The seven vanes generate pressure by the pumping action of the dynamic pressure generating grooves 1A, 1B and the spiral group 3A, float and rotate without contact. An upper cylinder 6 attached to a disk 5 that rotates with the shaft similarly rotates and records or reproduces electrical signals by a magnetic head (not shown) in contact with a magnetic tape (not shown).

As described above, according to the present invention, by providing the space 2F and the ventilation hole 3B, the lubricant 4A can be used even when the ambient temperature rises due to heat generation from the motor or when the pressure decreases inside the aircraft. , 4B, 4C are quickly discharged through the ventilation holes 2C, 3B, and there is no worry that the bubbles will expand and wash away the lubricant from the bearing gap.

Note that a dynamic pressure generating groove IA is provided on the outer periphery of the shaft 1.

1B is the same even if it is located on the inner periphery of the bearing hole 2A.

Note that the spiral groove 3 provided on the upper surface of the thrust member 3
The same applies even if A is provided on the lower end surface of the shaft 1.

Effects of the Invention As described above, the present invention press-fits and fixes a thrust member into a sliding hole communicating with a bearing hole, and creates a space between a dynamic pressure generating groove on the shaft side and a spiral groove on the thrust member side, and a space from this space to the outside. By providing communicating ventilation holes, a highly reliable hydrodynamic bearing can be obtained that does not mix the lubricant between the grooves and prevents lubricant from flowing out even under pressure and temperature changes. It will be done.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a hydrodynamic bearing according to an embodiment of the present invention.
Fig. 2 is an enlarged view of the thrust member, Fig. 3 is a sectional view of a conventional hydrodynamic bearing, and Fig. 4 is an enlarged view of the main parts of the thrust bearing of the hydrodynamic bearing. ...Shaft, 1A, 1B...Radial dynamic pressure generation groove, 2A...Bearing hole, 2B...
・Sleeve, 2E... Hole, 2F... Vacancy, 3... Thrust member, 3A... Spiral groove, 3B... Ventilation Hole, 4A...
・Lubricant for spiral grooves, 4B, 4C...Lubricant for radial dynamic pressure generating grooves. Name of agent: Patent attorney Toshio Nakao and 1 other person 2E
-1F 2nd Floor Figure 2, α4 Figure 3

Claims (3)

[Claims] (1) A sleeve having a bearing hole, a hole communicating with the bearing hole and coaxial with the bearing hole at one end, and a cylindrical thrust member fixed to the hole; It has a rotatable shaft, has a radial dynamic pressure generating groove on either the outer periphery of the shaft or the inner periphery of the bearing hole, and has a radial dynamic pressure generating groove on either the outer periphery of the shaft or the inner periphery of the bearing hole. A hydrodynamic bearing having a spiral groove on one side, a cavity between the dynamic pressure generating groove and the spiral groove, and a ventilation hole through which the sleeve passes through the cavity and communicates with the outside. (2) communicating the space on the outer peripheral surface of the thrust member with the outside;
A hydrodynamic bearing according to claim 1, wherein the hydrodynamic bearing is provided with a groove extending in the axial direction. (3) The radial dynamic pressure generating groove holds oil, and the spiral groove in the abutment area between the thrust member and the shaft end face holds grease manufactured using the oil as a base. Dynamic pressure type fluid bearing as described in scope 1.