JPS63318312A - Bearing device - Google Patents

Abstract

PURPOSE:To obtain a bearing device in which the relative shift of a rotational shaft to the change of load in an axial direction is small, by forming a projection at the opposite face to a thrust bearing. CONSTITUTION:When a rotary shaft 1 is rotated to generate pumping pressure through spiral grooves 8, pressure in the shaft end side of lubricating fluid film 7a between cylindrical opposing faces is increased and the rotary shaft 1 is equally pressurized along the full circumference by the pumping pressure. As a result, swing rotation is prevented and the stable rotation of the rotary shaft 1 is secured. And the pumping pressure is supplied to a gap between opposing faces 5a, 5b in an axial direction, and through this gap, it passes a through hole 10 bored it the center of the shaft of a bearing member 2 to flow out. The gap is kept constantly by lubricating fluid pressure supplied between the opposing faces 5a, 5b in the axial direction so that the rotary shaft 1 is held in a constant position.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a bearing device, particularly in a hydrodynamic bearing device.
The present invention relates to a bearing device including a thrust bearing in which a lubricating fluid film is formed between an end surface of a shaft and a surface facing the end surface thereof.

2. Description of the Related Art Conventionally, a thrust bearing as shown in FIG. 5 has been known as a bearing device having a thrust bearing function using a fluid film. In FIG. 5, 31 is a rotating shaft, and 32 is a rotating shaft 31.
These bearing members are arranged so as to surround the ends of the rotating shaft 31 and the bearing member 32 with a gap between them, and
A lubricating fluid film 35 such as air or oil is formed between 3a and 33b and between the opposing end surfaces 34a and 346, and the rotating shaft 31
A spiral group 3 that pumps lubricating fluid toward the shaft end by rotation of the rotary shaft 31 is provided on the opposite circumferential surface 33IL on the side.
6 is formed.

In this thrust bearing, a dynamic pressure bearing is formed between the opposing circumferential surfaces 33a and 33b by the wedge action of the lubricating fluid film 5 when the rotating shaft 31 rotates eccentrically, and by the pumping pressure by the spiral group 3G. An unstable phenomenon during high-speed rotation in this dynamic pressure slag bearing is avoided, and high pressure is applied to the lubricating fluid film 35 between the opposing end surfaces 34a and 34b by the pumping pressure, forming a thrust bearing with a large load capacity. .

Further, in Japanese Patent Application Laid-Open No. 56-22215, the present inventor has proposed a method in which a lubricating fluid film is formed between a relative movement surface between a rotating member and a shaft end face, and the relative movement surface is formed with irregularities in the circumferential direction. forming a first thrust bearing;
A second thrust bearing is provided which generates a force in a direction opposite to that of the first thrust bearing, and the rotating member is supported in a neutral position by the pressure generated in the lubricating fluid film of these thrust bearings, and We have proposed a bearing device in which the effective bearing area of the second thrust bearing is larger than that of the first thrust bearing.

However, in the thrust bearing, the lubricating fluid film 35 between the opposing circumferential surfaces 33a and 33b generated by the spiral group.
In the pressure distribution, as shown in FIG. 6, the pressure increases substantially linearly toward the shaft end, and the pressure of the lubricating fluid film 35 between the opposing end surfaces 34a and 34b is uniformly at its maximum pressure. . Therefore, the gap δ between the opposing end surfaces 34a and 34t+
Even if the pressure changes, the pressure change in the lubricating fluid film 35 is small.

Therefore, for example, when the external force F acting on the rotating shaft 31 in the axial direction changes, the relative displacement in the axial direction between the rotation $11131 and the bearing member 32 is large, and the restoring force when the external force F returns to its original state is also small. There was a problem that it was difficult to support the rotating shaft 31 and the bearing member 32 while keeping their relative positions constant.

On the other hand, according to the bearing device disclosed in Japanese Patent Application Laid-Open No. 56-22215, it is possible to support the shaft in a state where the axial displacement is small by bending even if the axial load changes. It is necessary to provide a flange to form the second thrust bearing, and to form two grooves to generate forces in opposite directions, resulting in high manufacturing costs. Ta.

The present invention solves the above-mentioned conventional problems, and provides a low-cost bearing device in which the relative displacement of the rotating shaft is small in response to load changes in the axial direction in a hydrodynamic bearing, the restoring force against displacement is large, and the structure and processing are simple. The purpose is to provide.

Means for Solving the Problem, α In order to achieve the above object, the present invention forms a lubricating fluid film between the mutually opposing cylindrical surfaces of a member fitted to the shaft and the pongee so as to be relatively rotatable, and also On one cylindrical surface,
A thrust bearing is formed by forming a shallow groove that has the effect of pumping the lubricating fluid in one direction by the relative rotation of the shaft, and forming a lubricating fluid film between the end surface of the shaft and the surface opposite thereto. A circular protrusion located at the center or an annular protrusion located at the outer periphery is formed on either surface of the thrust bearing, and in the case of a circular protrusion, a circular protrusion is formed on the outer periphery of the opposing surface In this case, a lubricating fluid under high pressure is supplied to the center of the opposing surface by the action of the shallow groove, and
It is characterized in that the vicinity of the center of the circular protrusion or the outer periphery of the circular protrusion is communicated with the low pressure side.

According to the present invention, as the pongee moves relative to each other, the lubricating fluid between the cylindrical surfaces is brought into a high pressure state by the action of the shallow grooves and is supplied toward the shaft end, passing through the gap between the opposing surfaces at the shaft end. It flows out to the low pressure side. At this time, a predetermined gap was formed between the opposing surfaces of the shaft end due to the lubricating fluid pressure, and the external force acting between the sleeve and the bearing member changed, causing a relative displacement between the two, and the gap changed accordingly. In this case, the pressure distribution changes significantly due to the circular protrusion or the annular protrusion formed on the opposing surface, and as a result, a large restoring force acts against the relative displacement. Therefore, even if the external force in the axial direction acting between the pongee and the bearing member changes, the axial gap between the sleeve and the bearing member does not change significantly, and the pongee or the bearing member can be supported at a constant position.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3. 1 is a rotating shaft, and 2 is a fixed bearing member disposed so as to surround the outer peripheral surface and one end surface of one end of the rotating shaft 1 with a gap therebetween.

In the gap between the cylindrical opposing surfaces 3a and 3b of the rotating shaft 1 and the bearing member 2 that face each other in the radial direction, and between the axially opposing surfaces 5a and Sb that face each other in the axial direction, a lubricating fluid film 7a of air or oil, etc. 7b are formed and constitute the ranofle bearing 4 and the thrust bearing 6, respectively. A plurality of spiral groups 8 are formed on the cylindrical facing surface 3a on the outer periphery of the rotating shaft 1. As a specific example, this spiral group 8 has a depth of several micrometers to several tens of micrometers and a width of several hundred micrometers.
It is formed into a rectangular cross-sectional shape of 11 to several liters.

Further, a circular protrusion 9 is formed on the axially opposing surface 5a on the rotating shaft 1 side, concentrically with the axis of the rotating shaft 1, and the axially opposing surface 5b on the bearing member 2 side is formed in a planar shape. has been done. Furthermore, the end face of the circular protrusion 9 is also formed into a plane parallel to the axially opposing surface 5b on the bearing member 2 side. A through-hole 10 is provided. Said circular protrusion 9
The protrusion height d is about several tens of μm to several 100 μm,
In the embodiment, the outer diameter r of the circular protrusion 9 is the outer diameter r of the rotating shaft 1.
It was set to approximately 1/2 of 2.

In the above configuration, when the rotating shaft 1 is rotated, pumping pressure is generated in the spiral group 8, and the pressure on the shaft end side of the lubricating fluid film 7a between the cylindrical opposing surfaces 3a and 3b increases, and this pumping pressure The rotating shaft 1 is evenly pressurized over its entire circumference.

As a result, whirling rotation is prevented and stable rotation of the rotating shaft 1 is ensured. Further, the pumping pressure is supplied to the gap between the axially opposing surfaces 5a and Sb, and flows out through the gap through the through hole 10 bored at the axial center position of the bearing member 2. The gap is kept constant by the lubricating fluid pressure supplied between the axially opposing surfaces 5a15b, and the rotating shaft 1 is supported at a constant position.

Here, as shown in FIG. 2(a), the pressure distribution in a state where a constant external force F acts and the distance between the axially opposing surfaces 5a and 5b is δI is as shown by the curve A in FIG. It is assumed that In addition, “=0” in Fig. 3 is
The center position of the circular protrusion 9 is shown. Po is the maximum pumping pressure by the spiral group, and the axially opposing surface 5
The gap is δ between the outer periphery of a and the outer periphery of the circular protrusion 9.
6, and the pressure drop is small because the fluid resistance is small. On the other hand, between the outer peripheral edge of the circular protrusion 9 and the through hole 10, the gap is δ, -d, and the fluid resistance increases and the pressure changes rapidly. The rotating shaft 1 is supported at a fixed position by the sum of the pressures in this pressure distribution. From this state, when the distance between the axially opposing surfaces 5a and 5t+ increases to δ2 as shown in FIG. 2(b), the pressure distribution changes to the pressure P at the outer periphery of the rotating shaft 1, as shown by curve B in tIS3. The pressure distribution state is close to a straight line from the point to the opening pressure at the axial center position. As a result, the force opposing the external force F is reduced by a force corresponding to the area indicated by diagonal lines between the curves HA and B, so that the external force F restores the rotating shaft 1 to its original position. Furthermore, by obtaining a large restoring force with respect to the displacement of the rotating shaft 1, that is, the amount of change in the gap δ, the rotating shaft 1 can be supported with extremely small displacement even in response to changes in the external force F. be.

In the above embodiment, the spiral group 8 and the thrust bearing 6 are arranged at one end of the rotating shaft 1, and the circular protrusion 9 is formed at the center of the axially opposing surface 5a of the rotating shaft 1. The present invention is not limited to this.

For example, as in the second embodiment shown in FIG. 4, the spiral group 18 may be arranged at one end of the rotating shaft 11, and the thrust bearing 16 may be arranged at the other end.

In that case, in order to introduce the pumping pressure from the spiral group 18 from one end of the rotating shaft 11 to the thrust bearing 16 at the other end, a communicating path 12 is bored at the axial center position of the rotating shaft 11. The thrust bearing 16 is configured between an axially opposing surface 15a of the other end of the rotating shaft 11 and an axially opposing surface 15b of the upper bearing member 14, which face each other, and the communication path 12 is formed between the axially opposing surface 15a of the rotating shaft 11 and the axially opposing surface 15b of the rotating shaft 11. 15a is opened at the center position, and an annular protrusion 19 is formed on the outer periphery of this axially opposing surface 15a. In FIG. 4, 13 is an upper bearing member;
Reference numeral 17 denotes a flange formed at the intermediate portion of the rotating shaft 11, and this embodiment is a bearing for maintaining the distance fiH from the leveling surface 20 of the lower bearing member 14 to the upper surface 17a of the flange 17 accurately and constant. The device is configured. A pair of spiral groups 21a and 21b having different directions at the center are formed on the outer periphery of the lower end of the rotating shaft 11 for bearing in the lanoal direction.

In the above embodiment, an example was shown in which the rotating shaft is supported by a bearing member, but conversely, it can be similarly applied to the case where the shaft is fixed and a bottomed cylindrical body is made rotatable. Alternatively, it may be formed on any cylindrical bearing surface on the bottomed circular body side.

Furthermore, the shallow grooves that generate the pumping pressure need not be in the form of a spiral groove like the spiral group 8.18.
In short, any groove may be used as long as it pumps the lubricating fluid in one direction by the relative rotation between the cylindrical bearing surface and the shallow groove.

Effects of the Invention According to the bearing device of the present invention, as described above, the lubricating fluid is supplied between the opposing surfaces of the shaft end by the pumping action of the shallow groove as the pongee rotates relative to each other, and a thrust bearing is formed. When the pongee and the bearing member are displaced relative to each other, and the gap between the opposing surfaces changes accordingly, the pressure distribution will change significantly due to the circular protrusion or annular protrusion formed on the opposing surfaces. A large restoring force acts against relative displacement.

Further, even if the external force in the axial direction acting between the glaze and the bearing member changes, the axial distance between the shaft and the bearing member does not change significantly, and the pongee or the bearing member can be supported at a constant position. Moreover, it is only necessary to form a circular protrusion or an annular protrusion on the end face of the shaft, and the structure and processing are extremely simple and can be manufactured at low cost.

[Brief explanation of drawings]

Figures 1 to 3 show an embodiment of the present invention, with Figure 1 being a vertical front view, and Figures 2 (a) and (b) being cross-sectional views of the bearing member in its operating state. 3 is a radial pressure distribution diagram at the shaft end, and FIG. 4 is a diagram of the second embodiment of the present invention.
FIG. 5 is a partially sectional front view of the embodiment, FIG. 5 is a sectional front view of a conventional bearing member, and tSa is a pressure distribution diagram in the coaxial direction. 1.11・・・・・・・・・・・・・・・Rotating shaft 2.14・・・・・・・・・・・・・・・Bearing members 5a, 5b・......Axial opposing surface 6.16...Thrust bearings 7a, 7b...・・・・・・・・・
Lubricating fluid film 8.18・・・・・・・・・・・・・・・
・・Spiral Group 9・・・・・・・・・・・・・・・
.........Circular protrusions 15a, 15
11...Axially opposite surface 19...
・・・・・・・・・・・・・・・・・・・・・・・・ Annular protrusion. The agent, Toshio Nakao, is a patent attorney.

Claims (1)

[Claims] A lubricating fluid film is formed between mutually opposing cylindrical surfaces of a shaft and a member that is relatively rotatably fitted to the shaft, and the lubricating fluid is pumped in one direction to one of the cylindrical surfaces by the relative rotation of the shaft. A thrust bearing is formed by forming a shallow groove having the action of A circular protrusion or an annular protrusion located on the outer periphery is formed, and the shallow groove is formed on the outer periphery of the opposing surface in the case of the circular protrusion, and in the center of the opposing surface in the case of the annular protrusion. A bearing device characterized in that a lubricating fluid brought into a high pressure state by the action is supplied, and the vicinity of the center of the circular protrusion or the outer circumference of the annular protrusion is communicated with a low pressure side.