JPH033805B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrodynamic spindle device using a hydrodynamic cylindrical groove bearing.

As shown in FIG. 1, a conventional spindle device for a motor main shaft of an audio equipment has a spherical body 3 disposed on a support member 2 fixed to a housing 1, and this spherical body 3 forms a concave shape provided on one end surface of a main shaft 4. It contacts the conical surface 5 and supports the thrust load of the main shaft 4. Furthermore, two sintered oil-impregnated bearings 6 and 7 having a larger coefficient of linear expansion than the main shaft 4 are fixed to the housing 1, and the radial load of the main shaft 4 is supported by these two sintered oil-impregnated bearings 6 and 7. Further, a rotor 8 fixed to the main shaft 4 and a stator 9 fixed to the housing 1 face each other on a cylindrical surface with a gap 11 in the circumferential direction. is fixed, and information from the disk 12 is read by an optical pickup 13 disposed around the outer periphery of the rotor 8.

In such a spindle device, when the main shaft 4 rotates, the sphere 3 rotates in point contact with the support member 2, which tends to cause uneven rotation, and the wear between the sphere 3 and the support member 2 increases, reducing durability. Inferior. In addition, since the sintered oil-impregnated bearings 6 and 7 cannot have good coaxiality between the machined inner and outer diameters, the inner diameter surface of the upper sintered oil-impregnated bearing 6 is eccentric to the inner diameter surface of the lower sintered oil-impregnated bearing 7, and the bearing clearance 14, Since it is difficult to make the rotation speed 15 small, the bearing rigidity is low and so-called whirl, in which the main shaft 4 swings around at a frequency of about 1/2 of the rotation speed, is likely to occur. Further, since the bearing surfaces of the outer diameter surface of the main shaft 4 and the inner diameter surfaces of the sintered oil-impregnated bearings 6 and 7 slide with each other in a state of boundary lubrication, small irregular runouts in the radial direction occur.

Furthermore, sliding noise is generated from the sintered oil-impregnated bearings 6 and 7.

Further, the hydrodynamic cylindrical groove bearing shown in FIG. 2 of Japanese Patent Publication No. 48-4498 has a radial inner surface 4 of a cylindrical hole provided in a housing 5 and a flat thrust bottom surface. The main shaft 1 disposed in the shaped hole has a cylindrical radial outer surface 3 and a convex conical thrust end surface 11. The groove 2 for generating dynamic pressure provided in the radial outer surface 3 transfers the lubricant in the gap between the radial inner surface 4 and the radial outer surface 3 to the outer periphery of the thrust bottom surface and the outer periphery of the thrust end surface during rotation of the main shaft 1. The effect is to flow out into the pressure chamber 6 between. The housing 5 is provided with a communication hole 12 communicating from the radial inner surface 4 to the upper surface of the housing 5, and this communication hole 12 faces the radial outer surface 3 when the bearing is at rest.

Therefore, when the main shaft 1 rotates and floats, the flow hole 1
2 opens into the pressure chamber 6, the lubricant in the pressure chamber 6 flows out to the outer peripheral surface of the main shaft 1 through the communication hole 12, and the flying height of the main shaft 1 is kept almost constant. However, since it is difficult to accurately provide the lower end opening 13 of the communication hole 12 in the vicinity of the boundary 14 between the radial outer surface 3 and the thrust end surface 11 in terms of machining, it is difficult to keep the flying height of the main shaft 1 small.

The invention aims to eliminate each of the aforementioned drawbacks. Next, embodiments of the present invention will be described based on the drawings. In FIG. 2, the hydrodynamic cylindrical groove bearing is composed of a housing 20 and a main shaft 21, and the housing 20 is provided with a cylindrical hole 22. A cylindrical radial inner surface 24 is provided on the inner peripheral surface of the cylindrical hole 22, and a planar thrust bottom surface 25 is provided on the bottom surface of the cylindrical hole 22. An inner circumferential groove having a rectangular cross section is provided as a circumferential groove 26 in the upper part of the radial inner surface 24, and a concave conical lubricant reservoir 27 is provided at the opening of the cylindrical hole 22. Said cylindrical hole 22
A main shaft 21 is disposed on the main shaft 21, and a cylindrical radial outer surface 28 that faces and cooperates with a radial inner surface 24 is provided on the outer peripheral surface of the main shaft 21. The radial outer surface 28 is provided with a spiral groove 29 for generating dynamic pressure, and one end surface of the main shaft 21 is provided with a convex spherical thrust end surface 31 that faces and cooperates with the slite bottom surface 25. ing. A pressure chamber 45 is formed between the outer peripheral surface of the thrust bottom surface 25 and the outer peripheral portion of the thrust end surface 31. The groove 29 for generating dynamic pressure is used to absorb lubricant in the radial bearing clearance 46 between the radial inner surface 24 and the radial outer surface 28 during operation of the hydrodynamic spindle device, that is, during rotation of at least one of the main shaft 21 and the housing 20. This acts to cause the water to flow out into the pressure chamber 45. As shown in FIG. 3, a communication hole 33 that opens into the circumferential groove 26 is provided in the center of the thrust end surface 31, and this communication hole 33 connects to an axial hole 331 provided in the thrust end surface 31. It is composed of a hole 332 that is perpendicular to the shaft that communicates the hole 331 with the outer circumferential surface of the main shaft 21 . Therefore, the communication hole 33 communicates with the outer surface of the main shaft 21. The thrust end surface 31 has an annular contact surface 37 around the flow hole 33 that contacts the thrust bottom surface 25 when the hydrodynamic spindle device is at rest and rotates at low speed.
A stator 40 is fixed to the lower part of the outer circumferential surface of. A rotor 42 made of permanent magnets is fixed to the main shaft 21 and is opposed to the stator 40 in a plane with an axial clearance 41 in between.The rotor 42 and the stator 40 constitute a motor and a drive mechanism. Since the rotor 42 attracts the stator 40, the main shaft 21 is thrust at the bottom surface 25 by the rotor 42.
The pressure chamber 45 between the thrust bottom surface 25 and the thrust end surface 31, the radial bearing clearance 46 between the radial inner surface 24 and the radial outer surface 28, the circumferential groove 26, the lubricant reservoir 27, and the circulation A lubricant is present in each hole 33. Note that the lubricant referred to in this invention refers to oil, grease, water, gas such as air, and molten metal.

In the hydrodynamic spindle device configured as described above, the thrust bottom surface 25 and the thrust end surface 31 are in contact when the main shaft 21 is stationary and rotating at low speed.
When the main shaft 21 rotates, the lubricant in the circumferential groove 26 flows into the pressure chamber 45 through the radial bearing clearance 46 due to the pumping action of the dynamic pressure generating groove 29, and the main shaft 21 floats. When the main shaft 21 floats up, the communication hole 33 opens into the pressure chamber 45.
The lubricant in 5 flows out into the circumferential groove 26 through the flow hole 33. In this case, the pressure of the lubricant in the pressure chamber 45 is adjusted by a slight change in the flying height of the main shaft 21 and is approximately constant, so that a constant thrust load capacity is obtained. Further, although the thrust end surface 31 rotates without contacting the thrust bottom surface 25, the flying height of the main shaft 21 can be kept small. Furthermore, distribution hole 3
The lubricant pushed out in the radial direction from 3 is in the circumferential groove 2.
6 and then flows into the radial bearing clearance 46, so the lubricant does not flow out from the circulation hole 33 concentrated in a localized area within the narrow radial bearing clearance 46, and the flow direction does not change suddenly, so the lubricant flows smoothly. The lubricant is circulated and is sufficiently supplied to the radial bearing clearance 46. Further, since radial pressure is generated in the lubricant within the radial bearing clearance 46, it has a radial load capacity, and the radial outer surface 28 rotates without contacting the radial inner surface 24. Furthermore, due to the pumping action of the groove 29 for generating dynamic pressure, the lubricant in the lubricant reservoir 27 is pumped into the radial bearing clearance 46.
Since the lubricant flows into the circumferential groove 26 through the lubricant, the groove 29 for generating dynamic pressure also functions as a seal to prevent the lubricant from leaking from the radial bearing clearance 46 to the outside of the housing 20. In addition, since there is a lubricant reservoir 27 at the opening of the housing 20, the lubricant in the radial bearing clearance 46, which decreases due to scattering and evaporation, is replenished from the lubricant reservoir 27, and even if the main shaft 21 accidentally rotates in the opposite direction. Since the lubricant is retained by the lubricant reservoir 27, leakage of the lubricant to the outside of the housing 20 can be prevented.

FIG. 4 shows another embodiment of the hydrodynamic cylindrical groove bearing used in the present invention, in which the housing 20 is fitted into the sleeve 201 and the bottom of the inner peripheral surface of the sleeve 201 by a method such as press fitting. Fixed sphere 202
It is composed of. The inner peripheral surface of the sleeve 201 is a cylindrical radial inner surface 24,
In addition, the sphere 202 has a convex spherical thrust bottom surface 25.
It is becoming. Also, the radial outer surface 28 of the main shaft 21
There is a circumferential groove 26 with a rectangular cross section on the upper part of the circumferential groove.
The thrust end face 31 is flat, and the thrust end face 31 has a flow hole 33 in the center thereof that opens into the circumferential groove 26, that is, communicates with the outer surface of the main shaft 21, as shown in FIG. It is provided.

FIG. 6 shows another embodiment of the hydrodynamic cylindrical groove bearing used in the present invention, in which the housing 20 is fixed and fitted to the inner peripheral surface of the outer cylinder 203 and the outer cylinder 203 by a method such as press fitting. It consists of a sleeve 201 and a cylindrical roller 204 that is fitted and fixed to the bottom of the inner peripheral surface of the sleeve 201 by a method such as press fitting. The inner peripheral surface of the sleeve 201 is a radial inner surface 24, and the cylindrical roller 204 is a flat thrust bottom surface 25. An inner circumferential groove 26 is provided in the upper part of the radial inner surface 24, and this circumferential groove 26 faces a circumferential groove 26 provided as an outer circumferential groove in the upper part of the radial outer surface 28. Further, in the center of the thrust bottom surface 25, there is a communication hole 3 that opens into a circumferential groove 26 provided on the radial inner surface 24.
3 is provided, and this circulation hole 33 is connected to the thrust bottom surface 2.
5, a communication hole 334 formed in a groove shape on the outer circumferential surface of the sleeve 201, a hole 335 perpendicular to the axis that communicates the communication hole 334 and the axial hole 333, and a communication hole 334. The opening hole 336 communicates with the circumferential groove 26.

FIG. 7 shows another embodiment of the present invention, in which the hydrodynamic cylindrical groove bearing of the first embodiment is used in an inverted position. A stator 40 is fixed to the lower part of the main shaft 21 constituting the hydrodynamic cylindrical groove bearing, and a rotor 42 made of magnets that faces the stator 40 in a plane with an axial clearance 41 in between is fixed to the housing 20. . The rotor 42
Since the stator 40 is attracted, the main shaft 21 is attracted to the thrust bottom surface 25 by the rotor 42, and the housing 20 is fitted into the sleeve 201 and the upper part of the inner peripheral surface of the sleeve 201 by a method such as press fitting. The shaft body 205 is fixed together with the shaft body 205. One end surface of the shaft body 205 is a flat thrust bottom surface 25, and the sleeve 2
01 is the radial inner surface 24.
A circumferential groove 26 is provided in the lower part of the radial inner surface 24;
is opposed to a circumferential groove 26 provided in the radial outer surface 28. In addition, an eighth
As shown in the figure, a communication hole 33 is provided which opens into the circumferential groove 26 provided in the radial outer surface 28, and a lubricant is present within the cylindrical hole 22. Therefore, the housing is configured to rotate 20 times.

FIG. 9 shows another embodiment of the present invention, in which the hydrodynamic cylindrical groove bearing of the first embodiment is used in an inverted position. A stator 40 is fixed to the lower part of the main shaft 21 constituting the hydrodynamic cylindrical groove bearing,
Further, a rotor 42 is fixed to the housing 20 and faces the stator 40 in a plane with an axial clearance 41 interposed therebetween. The housing 20 is an outer cylinder 203
and one sleeve 201 fitted and fixed to the upper part of the inner peripheral surface of the outer cylinder 203, and the other sleeve 206 fitted and fixed to the inner peripheral surface of the outer cylinder 203 at a distance from the one sleeve 201. One side and sleeve 2
Shaft body 20 fitted and fixed to the upper part of the inner peripheral surface of 01
5 serves as a thrust bottom surface 25, and one sleeve 201 serves as a radial inner surface 24. A communication hole 33 is provided in the center of the thrust bottom surface 25 and opens into the circumferential groove 26 provided at the lower part of the radial inner surface 24, and the other sleeve 2
A cylindrical radial inner circumferential surface 51 is provided on the inner circumferential surface of 06. The main shaft 21 is provided with a cylindrical radial outer circumferential surface 52 that faces and cooperates with a radial inner circumferential surface 51, and this radial outer circumferential surface 52 is provided with a herringbone-shaped groove 53 for dynamic pressure inventive action. There is. Therefore, the radial inner circumferential surface 51 and the radial outer circumferential surface 52 constitute a hydrodynamic cylindrical groove bearing, and a lubricant is present within the housing 20. Note that at least one of the radial inner circumferential surface 51 and the radial outer circumferential surface 52 has a groove 5 for generating dynamic pressure.
3 may be provided. A hollow chamber 61 is provided between the radial inner surface 24 and the radial inner circumferential surface 51 and between the main shaft 21 and the housing 20, and this hollow chamber 61 is connected to a hole-shaped communication path provided in the outer cylinder 203 of the housing 20. It communicates with the outside air via 62. Therefore, the radial bearing clearance 63 on the opening side is sealed with a lubricant such as grease, but when the ambient temperature of the hydrodynamic spindle device rises and the air in the hollow chamber 61 expands, the air in the hollow chamber 61 The lubricant in the radial bearing clearance 63 on the open side does not leak outward from below through the communication path 62.

FIG. 10 shows another embodiment of the present invention, in which a communication hole 33 provided in the center of the thrust bottom surface 25 opens to the outside of the housing 20, and this communication hole 33 is an axial hole provided in the thrust bottom surface 25. 333, and a shaft and a perpendicular hole 335 that communicate the axial hole 333 and the outer surface of the shaft body 205. Further, a lubricant such as air is present in the cylindrical hole 22, and when the housing 20 rotates, the lubricant such as air in the hollow chamber 61 is pumped into the radial bearing clearance 46 by the pumping action of the groove 29 for generating dynamic pressure. pressure chamber 45,
Since the lubricant flows out of the housing 20 through the communication hole 33, the lubricant such as air flows into the hollow chamber 61 from the communication path 62. Therefore, the communication hole 33 communicates with the outer surface of the main shaft 21 via the atmosphere and the communication path 62 and the like. The other parts of the illustrated embodiment are constructed almost the same as the embodiment shown in FIG.

In the illustrated embodiment, the groove 29 for generating dynamic pressure is provided on the radial outer surface 28, but the groove 29 for generating dynamic pressure is provided on the radial outer surface 28.
A groove 29 for generating dynamic pressure may be provided in at least one of the radial outer surface 28 and the radial outer surface 28 .

Further, the groove 29 for generating dynamic pressure may be an asymmetric herringbone-shaped groove in which the top part is shifted toward the thrust bottom surface 25 side.

Further, at least one of the thrust bottom surface 25 and the thrust end surface 31 may be provided with a communication hole 33 that communicates with an outer surface such as an outer peripheral surface or an end surface of the main shaft 21.

Furthermore, the circumferential groove 2 is provided with a communication hole 33 on at least one of the radial inner surface 24 and the radial outer surface 28.
6 may be opened.

Further, the cross-sectional shape of the circumferential groove 26 may be any shape, such as a semicircle or a polygon.

Furthermore, the thrust bottom surface 25 and the thrust end surface 3
1 may be a convex surface, a flat surface, or a concave surface. However, if at least one of the thrust bottom surface 25 and the thrust end surface 31 is spherical, the starting torque of the bearing is low, and the thrust bottom surface 25 and the thrust end surface 31 are spherical.
There is less wear with 1.

Further, the communication hole 33 can also be formed into various shapes. Furthermore, when a filter is inserted into the flow hole 33,
Cylindrical hole 22
Abrasion powder is not supplied to the inside of the spindle device, and the durability of the hydrodynamic spindle device can be improved. Moreover, wear powder is not discharged to the outside of the housing 20.

Furthermore, if oil or the like is present as a lubricant in the cylindrical hole 22, the housing 20 is attached to the thrust bottom surface 25.
A communication hole 33 that opens to the outside, such as the bottom surface or outer periphery of the
, and the communication hole 33 may communicate with the outer surface of the main shaft 21 through the inside of an oil tank disposed on the outer periphery of the housing 20 or the like.

Furthermore, a magnet such as a permanent magnet or an electromagnet is fixed to at least one of the housing 20 and the main shaft 21,
The main shaft 21 may be attracted to the thrust bottom surface 25 side by this magnet. Note that a magnetic body facing the magnet or a magnet facing the magnet may be fixed to the housing 20 or the main shaft 21.

Further, the housing 20 may be constructed from one member, or may be constructed from a plurality of members by combining the outer tube 203, the sleeve 201, the sphere 202, the cylindrical roller 204, the shaft body 205, and the like.

Furthermore, the dynamic pressure spindle device may be used vertically, horizontally, or inverted.

Further, the main shaft may rotate 21 times, the housing may rotate 20 times, or it may be used for relative rotation purposes.

Furthermore, if the linear expansion coefficient of the portion constituting the radial inner surface 24 of the housing 20 is lower than the linear expansion coefficient of the main shaft 21, the radial bearing clearance 46 will not increase even if the ambient temperature of the hydrodynamic spindle device increases, so the radial load Capacity reduction can be prevented.

Furthermore, if the linear expansion coefficient of the portion constituting the radial inner surface 24 of the housing 20 is smaller than the linear expansion coefficient of the main shaft 21, the radial bearing clearance 46 will become smaller as the ambient temperature of the hydrodynamic spindle device increases. Since the radial load capacity is increased, when oil, grease, or the like is used as the lubricant, it is possible to prevent a decrease in the radial load capacity caused by a decrease in the viscosity of the lubricant at high temperatures.

Note that the hydrodynamic spindle device can be used not only for audio equipment but also for video equipment, information equipment, and the like.

According to the hydrodynamic spindle device of the present invention, at least one of the thrust bottom surface 25 and the thrust end surface 31 has an annular contact surface 37 that contacts the thrust end surface 31 or the thrust bottom surface 25 when the hydrodynamic spindle device is at rest. Since there is a pressure chamber 45 between the outer periphery of the thrust bottom surface 25 and the outer periphery of the thrust end surface 31, the annular contact surface 37
The diameter of the outer peripheral portion of the thruster is smaller than the diameter of the radial outer surface 28, and since the contact area between the thrust bottom surface 25 and the thrust end surface 31 is small when the thruster is stationary, the starting torque is small. Also, during operation, the groove 29 for generating dynamic pressure
Pressure is generated in the lubricant in the pressure chamber 45 by the pumping action of 25 and the thrust end face 31 can be prevented from being damaged. Furthermore, during operation, pressure is generated in the lubricant in the small radial bearing clearance 46 due to the pumping action of the groove 29 for generating dynamic pressure, so the radial inner surface 24 and the radial outer surface 28 rotate without contact, resulting in low torque. , damage can be prevented, and the radial bearing rigidity is high. Furthermore, since the radial bearing clearance 46 of the hydrodynamic type cylindrical groove bearing is small, the main shaft 21
Furthermore, the housing 20 has no whirl or other whirling, and hardly any non-rotational speed synchronous component vibration occurs. Furthermore, since the main shaft 21 and the housing 20 rotate without contact, no sliding noise is generated from the bearings. Furthermore, since a communication hole 33 communicating with the outer surface of the main shaft 21 is provided in at least one of the central part of the thrust bottom surface 25 and the central part of the thrust end surface 31, when the main shaft 21 is displaced in the axial direction with respect to the housing 20, the pressure chamber 45 The lubricant inside flows out to the outer surface of the main shaft 21 through the circulation hole 33, and the pressure of the lubricant inside the pressure chamber 45 is adjusted by the axial displacement of the main shaft 21 with respect to the housing 20, and is almost constant. This has the effect that a thrust load capacity of 1 is obtained and the axial displacement of the main shaft 21 with respect to the housing 20 is small.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional spindle device, Figure 2 is a sectional view of a conventional spindle device;
The figure is a cross-sectional view of a hydrodynamic spindle device showing an embodiment of the present invention, FIG. 3 is a partial cross-sectional view of the main shaft shown in FIG. 2, and FIGS. 4 and 6 are hydrodynamic spindle devices used in the present invention. 5 is a partial sectional view of the main shaft shown in FIG. 4, and FIGS. 7, 9, and 10 are cross-sectional views of a hydrodynamic spindle device showing other embodiments of the present invention. 8 are partial sectional views of the main shaft shown in FIG. 7. In the figure, 20 is a housing, 21 is a main shaft, 22 is a cylindrical hole, 24 is a radial inner surface, 25 is a thrust bottom surface, 28 is a radial outer surface, 29 is a groove for generating dynamic pressure, 31 is a thrust end surface, and 33 is a circulation hole. , 37
42 is a contact surface, 42 is a rotor, 45 is a pressure chamber, and 46 is a radial bearing clearance.

Claims (1)

[Claims] 1. The cylindrical hole 22 provided in the housing 20 has a cylindrical radial inner surface 24 and a thrust bottom surface 25, and the main shaft 21 provided in the cylindrical hole 22 faces the radial inner surface 24. It has a cylindrical radial outer surface 28 that cooperates with the thrust bottom surface 25, and a thrust end surface 31 that faces and cooperates with the thrust bottom surface 25, and a pressure chamber is formed between the outer periphery of the thrust bottom surface 25 and the outer periphery of the thrust end surface 31. 45 is provided, and the radial inner surface 2
4 and the radial outer surface 28 during operation of the hydrodynamic spindle device.
A groove 29 for generating dynamic pressure is provided to cause the lubricant in the radial bearing clearance 46 between the radial outer surface 28 and the radial outer surface 28 to flow out into the pressure chamber 45, and the groove 29 is provided at the center of the thrust bottom surface 25 and the center of the thrust end surface 31. At least one of the thrust bottom surface 25 and the thrust end surface 31 is provided with a communication hole 33 communicating with the outer surface of the main shaft 21, and at least one of the thrust bottom surface 25 and the thrust end surface 31 is in contact with the thrust end surface 31 or the thrust bottom surface 25 when the hydrodynamic spindle device is at rest. The hydrodynamic spindle device has an annular contact surface 37 around the circulation hole 33, and a rotor 42 fixed to one of the housing 20 and the main shaft 21 faces a stator 40 fixed to the other. 2. The dynamic pressure type spindle device according to claim 1, wherein a filter is inserted into the flow path 33. 3. The hydrodynamic spindle device according to claim 1, wherein the linear expansion coefficient of the portion constituting the radial inner surface 24 of the housing 20 is less than or equal to the linear expansion coefficient of the main shaft 21. 4. The hydrodynamic spindle device according to claim 3, wherein the linear expansion coefficient of the portion constituting the radial inner surface 24 of the housing 20 is smaller than the linear expansion coefficient of the main shaft 21.