JPS631054Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a hydrodynamic bearing in which the amount of axial displacement of the shaft relative to the housing during rotation is small.

In a conventional hydrodynamic bearing device, as shown in FIG. 1, a cylindrical hole 2 provided in a housing 1 has a cylindrical radial inner surface 3 and a planar thrust bottom surface 4. The shaft body 5 disposed in the housing 1 has a cylindrical radial outer surface 7 having a spiral groove 6 and a convex conical thrust end surface 8, and the housing 1 has a thrust bottom surface 4 and a thrust end surface 8 when the shaft body 5 floats. A circulation hole 12 communicating with the upper surface of the housing 1 from the pressure chamber 11 between the end face 8 and the housing 1 is provided.

Therefore, when the shaft body 5 rotates and floats, the pressure chamber 1
The lubricant in the shaft body 1 flows out to the outer peripheral surface of the shaft body 5 through the circulation hole 12, and the flying height of the shaft body 5 is kept almost constant.

When using such a bearing in a flat motor etc., the rotor fixed to the shaft body 5 and the housing 1
Since the stator fixed to the rotor and the stator face each other in a plane with a small gap in the axial direction, it is desirable to reduce the relative displacement between the rotor and the stator. However, when the thrust bottom surface 4 and the thrust end surface 8 are in contact with each other, it is difficult to provide the circulation hole 12 with high accuracy near the boundary 13 between the radial outer surface and the thrust end surface. It is difficult to keep the relative displacement between the stator and the stator small. Further, since the circulation hole 12 cannot be precisely provided near the boundary 13 between the radial outer surface and the thrust end surface, many hydrodynamic fluid bearings cannot be made to have a constant flying height when mass-produced. Furthermore, since there is a small amount of clearance between the radial inner surface 3 and the radial outer surface 7, the lubricant in the pressure chamber 11 can pass through the circulation hole 12 to the shaft even if the shaft 5 does not float when the shaft 5 rotates. A small amount of the lubricant flows out onto the outer circumferential surface of the lubricant 5, preventing the pressure of the lubricant in the pressure chamber 11 from increasing, resulting in a low thrust load capacity. Further, since the circulation hole 12 has a small diameter and a long length, the cost of the hydrodynamic bearing is high. Furthermore, the suction force acting between the rotor and stator acts as a thrust load, so the thrust load is quite severe.When the shaft body 5 is stopped, the thrust end face 8 and the thrust bottom face 4 make point contact, so the maximum contact surface pressure is large, and the thrust There is a risk that dents may be formed on the bottom surface 4.

This invention aims to eliminate each of the aforementioned drawbacks.

Next, an embodiment of this invention will be described based on the drawings. In FIG. 2, a bearing member 22 made of synthetic resin is fitted and disposed on the inner peripheral surface of the housing 21, and a flat support member 24 disposed in contact with the bottom surface 23 of the bearing member is attached to the housing 21. It is fixed at The cylindrical hole 27 provided in the bearing member 22 has a planar thrust receiving surface 28 and a cylindrical radial inner surface 29, and the radial inner surface 29 is provided with a spiral groove 31 for generating dynamic pressure. There is.
The thrust receiving surface 28 has a convex portion 3 provided in the center.
2 and a spiral groove 33 for generating dynamic pressure provided around the convex portion 32 as shown in FIG. 3, and a circulation hole 34 is provided in the convex portion 32 in the axial direction. There is. The circulation hole 34 is located at the bottom surface 2 of the bearing member.
The bottom surface 23 of the bearing member has a larger diameter than the upper end surface of the bearing member 22. The flow groove 36 is formed on the bottom surface 23 of the bearing member.
This communicates with a communication hole 38 provided parallel to the shaft, and this communication hole 38 communicates with a groove-shaped communication path 39 provided parallel to the shaft on the outer peripheral surface of the bearing member 22. The communication passage 39 is open at the upper end surface of the bearing member 22, and the circulation hole 34 is connected to the communication groove 36, the communication hole 38, and the communication passage 3.
9, and the inner peripheral surface of the housing 21 and the bearing member 2
It communicates with an opening 41 of the cylindrical hole through a large diameter hole 40 surrounded by the upper end surface of the cylindrical hole. The shaft body 51 disposed in the cylindrical hole 27 has a planar thrust end face 52 facing the thrust receiving surface 28 and a cylindrical radial outer face 53 facing the radial inner face 29 . An annular contact surface 42 that contacts the thrust end surface 52 when the bearing is at rest is provided around the circulation hole 34. The large diameter hole 40, the radial bearing clearance 62 between the radial inner surface 29 and the radial outer surface 53, the thrust bearing clearance 63 between the thrust bearing surface 28 and the thrust end surface 52, and the circulation hole 3.
4. Communication groove 36, communication hole 38, and communication path 3
9, air, oil, and a lubricant such as grease are present.

The hydrodynamic bearing having the above configuration has a shaft body 51.
When at rest, the annular contact surface 42 and the thrust end surface 52
However, when the shaft body 51 rotates, the lubricant in the large diameter hole 40 is pumped into the radial bearing clearance 62 by the pumping action of the dynamic pressure generating groove 31 and the pumping action of the dynamic pressure generating groove 33. It flows into the thrust bearing clearance 63 through the shaft body 51, and the shaft body 51 floats up. When the shaft body 51 floats, the circulation hole 3
4 opens into the thrust bearing clearance 63, and the lubricant in the thrust bearing clearance 63 flows out into the large diameter hole 40 through the circulation hole 34, the circulation groove 36, the communication hole 38, and the communication passage 39. In this case, the pressure of the lubricant in the thrust bearing clearance 63 is adjusted by changes in the flying height of the shaft body 51 and is approximately constant, so that a constant thrust load capacity is obtained and the flying height of the shaft body 51 is small.

FIG. 4 shows another embodiment of this invention, in which a bearing member 22 is composed of a sleeve 122 and a flat plate-shaped thrust load receiving member 222 that abuts one end of the sleeve 122. Said sleeve 1
22 and the thrust load receiving member 222 are both made of synthetic resin, so the contact portion between the sleeve 122 and the thrust load receiving member 222 is sealed.

FIG. 5 shows another embodiment of this invention, in which a lip 322 provided at one end of a sleeve 122 made of synthetic resin is in contact with a thrust load receiving member 222 made of synthetic resin.

In this way, the sealing performance of the contact portion between the sleeve 122 and the thrust load receiving member 222 is improved. Note that the lip provided on the thrust load receiving member 222 may be in contact with one end of the sleeve 122.

In the illustrated embodiment, the groove-shaped communicating passage 39 is provided, but a communicating passage having a small diameter on the outer circumferential surface of the bearing member 22 may also be used.

Further, instead of the rotation of the shaft body 51, the housing 21 may be rotated, or it may be a relative rotation.

Furthermore, the hydrodynamic bearing may be used horizontally instead of vertically, or may be used upside down.

According to the hydrodynamic bearing of this invention, the convex portion 3
The circulation hole 34 provided in 2 is connected to the opening 41 of the cylindrical hole through a communication groove 36 provided in the bottom surface 23 of the bearing member and a communication passage 39 provided in the outer peripheral surface of the bearing member 22.
When the shaft body 51 is displaced in the axial direction with respect to the housing 21, the thrust bearing clearance 6
3 flows into the opening 41 of the cylindrical hole through the circulation hole 34, the communication groove 36, and the communication path 39, and the pressure of the lubricant in the thrust bearing clearance 63 increases against the housing 21 of the shaft body 51. It is adjusted by the axial displacement and is substantially constant, so that a constant thrust load capacity can be obtained and the axial displacement of the shaft body 51 with respect to the housing 21 can be kept small. Further, since the convex portion 32 has an annular contact surface 42 around the circulation hole 34 that contacts the thrust end surface 52 when the bearing is stationary, even if the shaft body 51 rotates, the shaft body 51 is displaced in the axial direction with respect to the housing 21. Otherwise, the lubricant in the thrust bearing clearance 63 will not flow into the circulation hole 34, resulting in a high thrust load capacity. Furthermore, since the annular contact surface 42 is provided on the synthetic resin bearing member 22, the annular contact surface 42 has elasticity, and the annular contact surface 42 and the thrust end surface 52
Good sealing properties at the contact area. Further, the radial inner surface 29 has a groove 31 for generating dynamic pressure, and the thrust receiving surface 28 has a groove 33 for generating dynamic pressure, so that the pumping effect of the groove 31 for generating dynamic pressure and the pumping effect of the groove 33 for generating dynamic pressure Since the thrust load capacity is high, the axial length of the radial inner surface 29 and the radial outer surface 53 can be shortened, and a compact hydrodynamic bearing can be obtained. Further, a cylindrical hole 2 provided in a bearing member 22 made of synthetic resin
7 has a planar thrust receiving surface 28 and a cylindrical radial inner surface 29 having a groove 31 for generating dynamic pressure. The circulation hole 34 provided in the convex portion 32 connects to the communication groove 36 provided in the bottom surface 23 of the bearing member and the communication groove 36 provided in the outer peripheral surface of the bearing member 22. Since it communicates with the opening 41 of the cylindrical hole through the passage 39, the bearing member 22 can be manufactured by injection molding of synthetic resin, which has good precision, can be mass-produced, and is inexpensive. Furthermore, since the convex portion 32 has an annular contact surface 42 around the circulation hole 34 that contacts the thrust end surface 52 when the bearing is at rest, the contact surface pressure between the annular contact surface 42 and the thrust end surface 52 when the bearing is at rest is reduced. Therefore, damage to the annular contact surface 42 and the thrust end surface 52 can be prevented. Furthermore, since the annular contact surface 42 is made of synthetic resin, it has good wear resistance and has a long service life.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional hydrodynamic bearing;
The figure is a sectional view of a hydrodynamic bearing showing one embodiment of this invention, Figure 3 is a plan view of the thrust bearing surface shown in Figure 2, and Figures 4 and 5 are other embodiments of this invention. FIG. 2 is a cross-sectional view of a hydrodynamic bearing. In the figure, 21 is a housing, 22 is a bearing member, 2
3 is a bottom surface of the bearing member, 24 is a support member, 27 is a cylindrical hole, 28 is a thrust bearing surface, 29 is a radial inner surface, 31 is a groove for generating dynamic pressure, 32 is a convex portion, 33
34 is a groove for dynamic pressure generation, 34 is a circulation hole, 36 is a communication groove, 39 is a communication path, 41 is an opening of a cylindrical hole, 42 is an annular contact surface, 51 is a shaft body, 52 is a thrust end surface, 53 is the radial outer surface.

Claims (1)

[Claims for Utility Model Registration] 1. A bearing member 22 made of synthetic resin is fitted and disposed on the inner peripheral surface of the housing 21, and a support member 24 disposed in contact with the bottom surface 23 of the bearing member is attached to the housing. 21, and the cylindrical hole 27 provided in the bearing member 22 has a planar thrust receiving surface 28 and a cylindrical radial inner surface 29 having a groove 31 for generating dynamic pressure. It has a convex portion 32 provided in the center and a groove 33 for generating dynamic pressure provided around the convex portion 32, and a circulation hole 34 provided in the convex portion 32 is provided in the bottom surface 23 of the bearing member. flow groove 36 and bearing member 22
The shaft body 51 arranged in the cylindrical hole 27 communicates with the opening 41 of the cylindrical hole through a communication path 39 provided on the outer peripheral surface of the cylindrical hole 27 . Radial inner surface 29
The convex portion 32 has an annular contact surface 42 in contact with the thrust end surface 52 when the bearing is at rest.
A dynamic pressure type fluid bearing having around 4. 2 Bearing member 22 is connected to sleeve 122 and sleeve 1
and a thrust load receiving member 222 that abuts one end of the hydrodynamic bearing according to claim 1, which is a registered utility model. 3 Lip 3 provided at one end of sleeve 22
22 is in contact with the thrust load receiving member 222. The hydrodynamic bearing according to claim 2, wherein the bearing member 22 contacts the thrust load receiving member 222. 4. The hydrodynamic bearing according to claim 2, in which a lip provided on the thrust load receiving member 222 contacts one end of the sleeve 122.