JPS631053Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a hydrodynamic bearing device used in rotating units of office machines, video equipment, information equipment, optical equipment, and the like.

Conventional equipment of this kind, e.g. laser beam
As shown in Fig. 1, the hydrodynamic bearing device used in the rotating unit of a rotating polygonal mirror light polarizer used in a printer has one end of a fixed shaft 2 fixed to a base. A sleeve 3 is fitted and disposed, and a spiral groove 5 is provided on the outer diameter surface of the fixed shaft 2, and a thrust end surface 6 at the other end of the fixed shaft 2 is provided with a groove 5 as shown in FIG. , a circulation hole 8 communicating with the radial bearing clearance 7 between the outer diameter surface of the fixed shaft 2 and the inner diameter surface of the sleeve 3 is provided, and the radial bearing clearance 7 and the thrust end surface 6 and the sleeve 3 facing the thrust end surface 6 are provided. Grease was inserted into the pressure chamber 12 between the thrust bearing surface 11 and the thrust bearing surface 11, respectively.

Therefore, when the sleeve 3 rotates, the grease in the radial bearing clearance 7 flows into the pressure chamber 12 due to the pumping action of the spiral groove 5, and the sleeve 3 floats up. When the sleeve 3 floats, the grease in the pressure chamber 12 flows out from the circulation hole 8 to the radial bearing clearance 7, so the sleeve 3 rotates while maintaining a very small floating amount. In this case, the pressure distribution of the grease in the radial bearing clearance 7 gradually increases from the base side to the thrust bearing surface 11 side, as shown by the dashed line in Fig. 1, so the pressure of the grease on the base side increases. is low, and the base side portion 13 of the sleeve swings around. In addition, wear powder generated by friction between the thrust end face 6 and the thrust bearing surface 11 during startup and stop exists in the radial bearing clearance 7, the pressure chamber 12, and the circulation hole 8. damage is accelerated. Furthermore, since hydrodynamic bearings are lubricated with grease, the sleeve 3
The polygon mirror 14 fixed to the polygon mirror 14 becomes dirty, and the performance of the polygon mirror 14 deteriorates.

The object of this invention is to provide a hydrodynamic bearing device in which the sleeve swings less, the thrust end face and the thrust bearing surface are less damaged, and the area around the bearing is kept clean.

Next, an embodiment of this invention will be described based on the drawings. In FIG. 3, one end of a fixed shaft 22 is fixed to a base 21, and a groove 23 for generating dynamic pressure is provided on the outer diameter surface of this fixed shaft 22. The groove 23 for generating dynamic pressure is a unidirectional spiral groove 12.
3 and a V-shaped herringbone groove 223 provided on the side of the base 21 from the unidirectional spiral groove 123, and the other end of the fixed shaft 22 is a flat thrust end surface 24. There is. A sleeve 26 is fitted to the fixed shaft 22, and the sleeve 26 is composed of a cylindrical sleeve body 126 and a cylindrical roller 226 that is fitted and fixed to the inner peripheral surface of the sleeve body 126. . The inner surface of the sleeve body 126 faces the groove 23 for generating dynamic pressure, and the cylindrical roller 226 has a thrust end surface 24.
A convex spherical thrust bearing surface 27 is provided opposite to the thrust bearing surface 27 . A communication hole 28 that communicates with the outside world is provided in the central part of the thrust bearing surface 27 in the axial direction, and the thrust end surface 24 communicates with an annular contact portion 124 that contacts the thrust bearing surface 27 when the bearing is stationary and rotates at low speed. It is provided around the hole 28.
A polygon mirror 31 and a rotor 32 constituting a motor drive mechanism are fixed to the outer circumferential surface of the sleeve 26, and an outer cylinder 33 is fixed to the outer circumference of the base 21. A stator 34 facing the rotor 32 is fixed to the inner peripheral surface of the outer cylinder 33, and the outer cylinder 33 is provided with a glass window 35 through which laser light passes. A cover 36 that covers the sleeve 26 is fixed to the outer cylinder 33, and the hydrodynamic bearing device is hermetically sealed.

When the sleeve 26 rotates with the above configuration, the air or gas near both ends of the herringbone groove 223 in the axial direction flows into the center of the herringbone groove 223 in the axial direction, and the spiral The gas near the groove 123 flows into the pressure chamber 41 between the thrust end face 24 and the thrust bearing surface 27, and the sleeve 26 floats up. When the sleeve 26 floats up, the pressure chamber 41
Since the gas inside flows out to the outside world through the communication hole 28, the sleeve 26 maintains a very small amount of flying height and rotates without contacting the thrust end face 24. In this case, the fixed shaft 22
The pressure distribution of gas within the radial bearing clearance 42 between the outer diameter surface of the sleeve 26 and the inner diameter surface of the sleeve 26 is as shown by the dashed line in FIG.
Since the pressure at both ends of the sleeve 26 in the axial direction becomes high, swinging of the sleeve 26 is reduced. Furthermore, even if wear powder is generated due to friction between the thrust end face 24 and the thrust bearing surface 27 during startup and stop, the wear powder is discharged to the outside from the communication hole 28, so damage to the thrust end face 24 and the thrust bearing face 27 is prevented. Does not accelerate. Further, the gas in the radial bearing clearance 42 flows through the pressure chamber 41, the communication hole 28, and the outside world into the radial bearing clearance 42 again due to the pumping action of the spiral groove 123, so that the rotor that constitutes the drive mechanism of the motor 32 and stator 34 are cooled, and heat generation of the motor can be prevented.

FIG. 4 shows another embodiment of this invention, in which the first embodiment is almost inverted. The thrust end surface 24 has a convex spherical shape, and this thrust end surface 24 faces a planar thrust bearing surface 27 provided on the cylindrical roller 226. As shown in FIG. 5, a communication hole 28 communicating with the outside world is provided in the center of the thrust end surface 24, and this communication hole 28 is connected to an axial hole 128 provided in the thrust end surface 24.
and a hole 228 extending perpendicularly to the axis that communicates from the axial hole 128 to the outer diameter surface of the fixed shaft 22. The thrust end face 24 has an annular contact portion 124 around the communication hole 28 that contacts the thrust bearing surface 27 when the bearing is stopped and rotated at low speed, and the groove 23 for generating dynamic pressure has a spiral groove 123.
A second herringbone groove 323 is provided closer to the thrust bearing surface 27 side. A first outer groove 52 is provided between the spiral groove 123 and the herringbone groove 223,
Further, a second outer circumferential groove 5 is formed between the spiral groove 123 and the second herringbone groove 323.
3 is provided. Sleeve 2 of the base 21
The side part of 6 is a magnet 54, and the sleeve 2
The side portion of the base 21 of No. 6 is made of a ferromagnetic material 55.
The magnet 54 attracts the ferromagnetic material 55, and the thrust magnetic bearing composed of the magnet 54 and the ferromagnetic material 55 supports the weight of the sleeve 26, the polygon mirror 31, the rotor 32, and the like. Note that the space between the base 21 and the sleeve 26 is a bearing clearance 56 of the thrust magnetic bearing, and an electromagnet, a permanent magnet, a ferromagnetic material, or the like can be used as a component of the magnetic bearing.

FIG. 6 shows another embodiment of this invention, in which the thrust bearing surface 27 has a cylindrical protrusion 224 in the center.
It is becoming. The end surface of the protruding portion 224 is planar, and a communication hole 28 communicating with the outside world is provided in the central portion of the protruding portion 224 in the axial direction. The communication hole 28 has an annular contact portion 124 that contacts the thrust bearing surface 27 during rotation and low speed rotation.

In this way, the cylindrical protrusion 224 is provided in at least one of the central part of the thrust end face 24 and the central part of the thrust bearing surface 27, so that the thrust end face 24 and the thrust bearing surface 27 are connected to each other when the bearing is stationary and rotates at low speed. When the contact is made in a plane, the contact area of the annular contact portion 124 does not change even if the thrust end face 24 and the thrust bearing surface 27 wear out.

Note that a groove for generating dynamic pressure may be provided on the inner diameter surface of the sleeve 26, and a groove for generating dynamic pressure may be provided on both the inner diameter surface of the sleeve 26 and the outer diameter surface of the fixed shaft 22 opposite to the inner diameter surface of the sleeve 26. A groove 23 may be provided.

Further, a communication hole 28 communicating with the outside world may be provided in both the thrust end surface 24 and the thrust bearing surface 27.
Both may have a convex spherical shape. Note that if one of the thrust end face 24 and the thrust bearing surface 27 is formed into a convex spherical shape and a communicating hole 28 is provided in one, and the other is made into a flat shape or a concave spherical shape with a radius larger than the radius of the one, the other Do not dig into the communication hole 28 provided on one side.

When at least one of the thrust end surface 24 and the thrust bearing surface 27 is formed into a convex spherical shape in this way, the starting torque is low.

Further, the sleeve body 126 and the cylindrical roller 226 are integrated into one member.
may also be configured.

Further, the herringbone-shaped groove 223 and the second herringbone-shaped groove 323 may have a V-shape or a dogleg shape, or may be asymmetrical.

According to the hydrodynamic bearing device of this invention, the groove 23 for generating dynamic pressure includes a spiral groove 123 and a herringbone groove 223 provided closer to the base 21 than the spiral groove 123. Therefore, the pressure of the fluid at both ends of the radial bearing clearance 42 is high, and the swing of the sleeve 26 is small. In addition, at least one of the thrust end face 24 and the sleeve 26 is provided with a communication hole 28 that communicates the pressure chamber 41 with the outside world during operation of the bearing, so that friction between the thrust end face 24 and the thrust bearing surface 27 is prevented when the bearing is started or stopped. Therefore, even if abrasion powder is generated, the abrasion powder is discharged from the communication hole 28 to the outside world, so that damage to the thrust end face 24 and the thrust bearing surface 27 is not accelerated. Furthermore, since the fluid in the radial bearing clearance 42 and the pressure chamber 41 is discharged to the outside world from the communication hole 28, air or the like is used instead of grease or oil as a lubricant, so there is no contamination around the bearing. have an effect.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional hydrodynamic bearing device.
2 is a front view showing a part of the fixed shaft shown in FIG. 1 in cross section, FIG. 3 is a sectional view of a hydrodynamic bearing device showing an embodiment of this invention, and FIGS. 4 and 6. 5 is a cross-sectional view of a hydrodynamic bearing device showing another embodiment of this invention, and FIG. 5 is a front view showing a part of the fixed shaft shown in FIG. 4 in cross section. In the figure, 21 is a base, 22 is a fixed shaft, 23 is a groove for generating dynamic pressure, 123 is a spiral groove, 2
23 is a herringbone groove, 24 is a thrust end face, 26 is a sleeve, 27 is a thrust bearing surface,
28 is a communication hole, and 41 is a pressure chamber.

Claims (1)

[Claims for Utility Model Registration] (1) One end of a fixed shaft 22 is fixed to a base 21, and a sleeve 26 is fitted and disposed on the fixed shaft 22,
A pressure chamber 41 is provided between the thrust end surface 24 of the other end of the fixed shaft 22 and the thrust bearing surface 27 of the sleeve 26 facing the thrust end surface 24, and the inner diameter surface of the sleeve 26 and the sleeve 26
In a hydrodynamic bearing device in which a groove 23 for generating dynamic pressure is provided on at least one side of the outer diameter surface of the fixed shaft 22 opposite to the inner diameter surface of and a herringbone groove 223 provided closer to the base 21 than the spiral groove 123, and at least one of the thrust end face 24 and the sleeve 26 communicates the pressure chamber 41 with the outside world during operation of the bearing. A hydrodynamic bearing device characterized in that a communication hole 28 is provided. (2) The motion according to claim 1, wherein the groove 23 for generating dynamic pressure includes a second herringbone groove 323 provided on the side closer to the thrust bearing surface 27 than the spiral groove 123. Pressure type fluid bearing device. (3) The hydrodynamic bearing device according to claim 1 or 2, wherein the space between the base 21 and the sleeve 26 is a bearing clearance 56 of the thrust magnetic bearing. (4) A communication hole 28 is provided in at least one of the thrust end face 24 and the thrust bearing surface 27, and the annular contact portion 124 where the thrust end face 24 contacts the thrust bearing surface 27 when the bearing is stationary and when rotating at low speed is connected to the communication hole 28. 28. The hydrodynamic bearing device according to claim 1, which has a circumference of 28.