JP4063245B2 - Bearing device and motor using the same - Google Patents

Description

  The present invention relates to a hydrodynamic bearing used for a spindle motor or the like.

  Conventionally, in order to drive various rotating plates such as a polygon mirror, a magnetic disk, and an optical disk with high accuracy and high speed, various types of bearing devices using dynamic pressure such as oil have been proposed for the spindle motor. In general, these bearing devices are provided with a dynamic pressure generating groove in a plurality of dynamic pressure bearing portions, and support the rotation of the rotating member by the dynamic pressure generated by the pumping action of the dynamic pressure generating groove during rotation. ing.

  As an element for improving the reliability of the bearing device, prevention of fluid external leakage can be mentioned. As a measure to prevent oil spillage, there is a method of sealing the bearing piece end (on the open end side) without providing an air passage, etc. in order to shut off the oil spillage path. However, in order to avoid the discharge of oil due to the expansion and contraction of air, an assembling method in which the air is expelled by a special method such as vacuum lubrication is required, which increases the cost. Further, the oil including the excess oil in the bearing is less likely to flow and circulate, which is disadvantageous in terms of heat generation because it accelerates the deterioration of the oil and there is no exchange of heat with the outside. Therefore, a bearing structure that is easy to assemble by causing the sealed bearing piece end to communicate with the outside air, has less oil deterioration, and is advantageous for heat dissipation has attracted attention.

  However, there is a concern that oil leaks to the outside of the bearing, and as one means for preventing this leakage, the dynamic pressure generating grooves in the dynamic pressure bearing portion are pressurized with fluid toward each other. In order to make the applied force equally balanced, the difference in length between the longer side and the shorter side of the pattern width of the asymmetrical shape is set different from that of the other side. It is made equal (for example, refer patent document 2).

  FIG. 2 shows the structure of a conventional bearing device. In FIG. 2, the outer shape portion of the shaft 102 is inserted into the inner diameter portion of the sleeve 101. An oil is interposed in the gap so that the shaft is rotatable. A thrust member 103 having a convex spherical portion is attached to the bottom of the sleeve 101, and the convex spherical portion and the tip end portion of the shaft 102 constitute a thrust bearing.

  Herringbone grooves 104 and 105 are disposed at two locations on the inner diameter portion of the sleeve 101 from above to constitute a dynamic pressure radial bearing. The upper radial bearing gap is configured to communicate with the outside air, but the sleeve 101 is further provided with a notch 107, and the lower radial bearing gap is also configured to communicate with the outside air so that heat generated during rotation can be easily released to the outside. is doing. Further, the pattern width of the herringbone groove 104 is L1 and L2 from the upper side, and the pattern width of the herringbone groove 105 is L3 and L4 from the upper side. At this time, when L6 = L4-L3 and L5 = L1-L2, L6≈L5 ≧ 0 is set, and L6 and L5 are substantially equal.

In this configuration, when the shaft 102 rotates, dynamic pressure is generated in the herringbone grooves 104 and 105, and the oil is moved toward the space 106 according to the pattern of the herringbone grooves. That is, dynamic pressure is generated from the longer herringbone groove pattern width to the shorter one. At this time, since L6 and L5 are substantially equal, the difference between the pressure generated at the pattern width L1 and the pressure generated at the pattern width L2 is the pressure generated at the pattern width L4. And the pressure generated at the position where the pattern width is L3 is substantially equal, and the pressure applied to the space 106 from the vertical direction is almost balanced. For this reason, the air layer remaining in the space 106 does not go to one of the herringbone grooves, thereby preventing the oil from being pushed out from the radial bearing portion by air. Furthermore, although there is a slight amount of oil movement to the center of the bearing during rotation and movement in the reverse direction during stoppage, fluid and circulation occur with the excess oil in the bearing. Delaying the deterioration of
Japanese Patent Laid-Open No. 10-9252 (page 7, FIG. 1) Japanese Patent Laid-Open No. 11-153130 (page 9, FIGS. 1 and 2)

  However, in recent years, with the increase in the speed of the motor, with the above-described conventional configuration, it has become impossible to ignore the wrinkles of the rotating shaft that could be ignored until now. In particular, since a large amount of load is applied to various rotary plates of a spindle motor such as a polygon mirror, a magnetic disk, and an optical disk on the rotating shaft near the open end of the bearing, the amount of deflection is added and the swing is increased. That is, when compared between the open end side and the anti-open end side, a difference occurs in the amount of rotation of the rotating shaft, and the open end side swings more than the anti-open end side. Therefore, apparently, a pumping force that pushes oil from the open end side toward the non-open end side works, and the balance of the forces that are balanced by pressurizing the fluid toward each other is lost.

  As a result, the air layer remaining in the space between the two radial bearings moves toward the non-open end, and air from the air layer enters the radial bearing closer to the thrust bearing side and the other radial bearing A large amount of external air also enters the bearing from the open end side, causing a decrease in dynamic pressure due to lack of oil, and deteriorating the service life. In addition, the equipment may be contaminated due to oil spills to the outside.

  The present invention solves such a conventional problem, and an object of the present invention is to provide a bearing device capable of realizing high speed and long life.

In order to solve the above problems, the present invention provides a bearing having a structure in which a load is applied by a rotating plate to a rotating shaft near the open end side of a sleeve, and a pattern width on a thrust bearing side of a herringbone groove pattern closer to the thrust bearing. Where d is the width of the other pattern, c is the width of the herringbone groove pattern on the open end side of the other sleeve, b is the width of the pattern on the thrust bearing side, and a is the width of the other pattern, f = dc> 0, e = a−b> 0, and f> e.

  According to the first aspect of the present invention, the assembly is simple without sealing, the influence of the expansion and contraction of the air in the bearing is small, the oil does not flow out to the outside, and the dynamic pressure is reduced due to the entrainment of the air. Does not happen. Further, oil deterioration is prevented by oil flow and circulation in the bearing. In addition, heat can be exchanged with the outside, which is advantageous in terms of heat dissipation. Therefore, it is possible to realize a bearing device that can cope with high-speed rotation and can realize a bearing device that is low cost, high speed, long life, and does not pollute the equipment.

  Further, according to the invention of claim 2, by providing the oil repellent near the open end outlet, a force that causes the oil to flow toward the open end of the bearing due to variations in parts and rotational speed works. Even if it has, the sealing action with the oil repellent works, the oil can be prevented from flowing out from the open end of the bearing, and the reliability is improved. Furthermore, the corresponding rotation speed range can be widened, and it is possible to cope with variable speed specifications.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a longitudinal section of a bearing device according to Embodiment 1 of the present invention. In FIG. 1, an outer portion of a shaft 2 having a lower convex spherical surface portion is inserted into an inner diameter portion of a sleeve 1. An oil is interposed in the gap so that the shaft is rotatable. A thrust plate 3 and a bottom plate 4 are disposed at the bottom of the sleeve 1. The convex spherical portion of the shaft 2 and the thrust plate 3 constitute a thrust bearing. Herringbone grooves 5 and 6 are disposed at two locations on the inner diameter portion of the sleeve 1 from above to constitute a dynamic pressure radial bearing.

The upper radial bearing gap is configured to communicate with the outside air, and the sleeve 1 is further provided with a notch 7, and the lower radial bearing gap is also configured to communicate with the outside air.
Further, the pattern width of the herringbone groove 5 is a and b from the upper side, and the pattern width of the herringbone groove 6 is c and d from the upper side. At this time, f = dc> 0, e = ab> 0, and f> e are set.
In this configuration, when the shaft 2 rotates, dynamic pressure is generated in the herringbone grooves 5 and 6, and the oil is moved toward the space 8 according to the pattern of the herringbone grooves. That is, dynamic pressure is generated from the longer herringbone groove pattern width to the shorter one.

  At this time, paying attention to the shaft 2, various rotating plates (not shown) such as a polygon mirror, a magnetic disk, and an optical disk are attached to the open end side of the shaft 2. However, the run-out on the open end side increases, the run-out on the open end side of the shaft is larger than the run-out on the non-open end side, and the pumping force works from the larger to the smaller run-out, and the open end The force that pushes oil from the side toward the anti-open end side is generated, but the force of pushing back from the anti-open end side toward the open end side works from the relationship of f> e. The pressure applied from is almost balanced. Note that an oil repellent 9 is applied to the open end outer portion of the sleeve 1 of the shaft 2, and the oil repellent 9 performs an oil seal on the open end side.

  With these configurations, assembly is simple without sealing, the influence of expansion and contraction of the air in the bearing is small, there is no outflow of oil or entrainment of air, and there is no decrease in dynamic pressure. Bearings that prevent oil deterioration during flow and circulation, improve the heat dissipation effect by exchanging heat with the outside, can cope with high speed rotation, low cost, high speed, long life and do not pollute the equipment A device can be realized. In addition, the oil repellent prevents the oil from flowing out from the open end of the bearing, improving the reliability of parts and rotational speed variations, expanding the corresponding rotational speed range, and making it a variable speed specification. Can also be supported.

In the above description, the herringbone groove is engraved on the shaft side. However, the herringbone groove may be provided on the sleeve side, and can be applied to grooves having various shapes such as the depth, width, and angle of the groove. .
Furthermore, there are no restrictions on the bearing clearance, the shape of the oil reservoir inside and outside the bearing, the type of oil, and the like. Furthermore, although the example which applied the oil repellent agent to the shaft side was shown, you may apply | coat to the sleeve side and may apply | coat to both.

  In addition, an example has been shown in which the sleeve is provided with a notch to communicate the lower radial bearing with the outside air. it can. Moreover, there is no restriction | limiting also in the material and material which comprise components, You may deform | transform and change suitably. Needless to say, various modifications can be made without departing from the scope of the invention.

The bearing device of the present invention is easy to assemble, is less affected by air expansion and contraction in the bearing, does not flow out of the oil, does not decrease the dynamic pressure due to air entrainment, and does not deteriorate due to oil flow and circulation. It can be prevented and the heat dissipation effect is enhanced, so it is useful as a rotating device such as a motor that meets the demands for high speed, wide range of rotation speed, low cost and long life.

1 is a longitudinal sectional view showing a bearing device according to Embodiment 1 of the present invention. Longitudinal sectional view showing a conventional bearing device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Sleeve 2,102 Shaft 3,103 Thrust board 4 Bottom plate 5,6,104,105 Herringbone groove 7,107 Notch 8,106 Space 9 Oil repellent L1-4, a, b, c, d Herringbone groove Pattern width

Claims (2)

A rotary shaft, a sleeve having two radial bearings arranged side by side so as to rotatably support the rotary shaft, one end of which is opened, and one end of the rotary shaft are supported, and the other end of the sleeve is arranged. A thrust bearing provided, an air vent passage formed in a space formed by the thrust bearing and the radial bearing, and a herringbone groove provided in either one of the rotating shaft or the sleeve of the two radial bearings to open the sleeve In the configuration in which a load is applied to the rotating shaft near the end side, a pattern width on the thrust bearing side of the herringbone groove pattern closer to the thrust bearing is d, and the other pattern width is c. when the pattern width b, and the other pattern width was a of the thrust bearing side of the herringbone groove pattern of the open end of the sleeve, f = d- > 0, e = a-b> 0, the bearing device is characterized in that the f> e and the motor using it. 2. The bearing device according to claim 1 and a motor using the same, wherein an oil repellent is applied to at least one of a rotary shaft portion located outside the open end side sleeve or an outer exit surface of the open end side sleeve.