JP2005155911A - Fluid bearing device, spindle motor comprising the same, and recording disc driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing device capable of reducing the power consumption by reducing the axial loss torque while securing bearing rigidity, and improving the accuracy in rotation by stabilizing the rotation of a rotating shaft. <P>SOLUTION: In this fluid bearing device 1 comprising a bearing case 10, an end plate 20 and a shaft body 30, a cylindrical hole 11 of the bearing case 10 is a stepped cylindrical hole having a large-diameter part 11a and a small-diameter part 11b, the shaft body 30 is a stepped shaft body having a large-diameter part 31a and a small-diameter part 31b, a first dynamic pressure groove 51 is formed on any one of the large-diameter part 11a of the stepped cylindrical hole 11 and the large-diameter part 31a of the stepped shaft body 30, a second dynamic pressure groove 52 is formed on any one of the small-diameter part 11b of the stepped cylindrical hole 11 and the small-diameter part 31b of the stepped shaft body 30, a third dynamic pressure groove 53 is formed on a surface of a stepped part 11c of the stepped cylindrical hole 11, and microvoids respectively between opposite faces of the first through third dynamic pressure grooves are filled with the lubricant for generating dynamic pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The invention of the present application is a hydrodynamic bearing device capable of exhibiting a bearing function with respect to both radial and axial forces, and in particular, a hydrodynamic bearing device designed to reduce axial loss torque while ensuring bearing rigidity, and the fluid The present invention relates to a spindle motor provided with a bearing device and a recording disk drive device.

In recent years, office automation equipment such as computers, which are becoming increasingly larger and smaller,
Spindle motors used as driving devices and parts for rotating parts such as hard disk drives that are peripheral equipment have high reliability in terms of motor runout accuracy (NRRO (asynchronous runout)), noise, acoustic life, rigidity, etc. It is requested.

Conventionally, a compound ball bearing device constituted by combining a plurality of ball bearings is often used for the bearing portion of the rotating shaft of such a spindle motor. Recently, in hard disk drive devices and the like, there has been a strong demand for an increase in recording capacity, an improvement in impact resistance, a low noise and a high-speed data access. To meet these demands, a spindle motor Ball bearings have improved material composition and improved processing accuracy of inner and outer rings, rolling elements, etc., and as a result, further improved rotational accuracy has been achieved. However, the limitations of the rolling bearing itself have been recognized.
Installation of hydrodynamic bearings is in progress.

FIG. 10 shows a shaft rotation type spindle motor on which such a fluid bearing is mounted. The spindle motor 00 includes a base 02, a rotor hub 03 that is supported by the base 02 and rotates, and a hydrodynamic bearing device 01 interposed between the base 02 and the rotor hub 03.

The sleeve 010 of the hydrodynamic bearing device 01 is fitted and fixed to the inner peripheral surface of the cylindrical wall 07 at the center portion of the base 02. The rotary shaft 0 suspended from the rotor hub 03 is fixed to the sleeve 010.
30 is inserted. A minute gap between the sleeve 010 and the rotating shaft 030 is filled with lubricating oil, and a dynamic pressure groove (for example, a herringbone-shaped groove) 051 formed on the inner peripheral surface of the sleeve 010 as the rotating shaft 030 rotates. , 052, the rotating shaft 030 is rotatably supported in the radial direction in a non-contact state with the inner peripheral surface of the sleeve 010 by the dynamic pressure obtained by generating the lubricating oil pressure by the action of. Although the dynamic pressure grooves 051 and 052 are formed at two locations on the upper and lower sides of the inner peripheral surface of the sleeve 010, these dynamic pressure grooves may be formed on the outer peripheral surface of the rotating shaft 030.

Although not shown in detail, the dynamic pressure grooves (for example, the upper surface of the counter plate 020 and the lower end surface of the sleeve 010 facing the lower end surface and the upper end surface of the thrust ring 060 fitted to the lower end portion of the rotary shaft 030 respectively. Herringbone-shaped grooves) are formed, and the minute gaps between the facing surfaces where these dynamic pressure grooves face each other are filled with lubricating oil, and by the action of these dynamic pressure grooves as the rotary shaft 030 rotates. The thrust ring 060 is rotatably supported in the axial direction in a non-contact state with the upper surface of the counter plate 020 and the lower end surface of the sleeve 010 by the dynamic pressure obtained by generating the pressure of the lubricating oil. These dynamic pressure grooves
The thrust ring 060 may be formed on the lower end surface and the upper end surface, respectively.

Therefore, the base 02 is connected to the rotating shaft 030 of the rotor hub 03 via the hydrodynamic bearing device 01.
Is supported rotatably. In addition, the structure of the motor unit including the stator 05, the permanent magnet 06, and the like is basically not different from a spindle motor using a conventional compound ball bearing.

In such a conventional hydrodynamic bearing device 01, the rotating shaft 030 having the same diameter over the entire length and the sleeve 010 having the cylindrical hole with the same diameter over the entire length are used, so that the comparison is made by connecting the rotor hub 03. Compared to the upper part of the bearing where high bearing rigidity is required,
The diameter of the lower portion of the bearing, which requires relatively low bearing rigidity, is excessive, and the shaft loss torque increases accordingly, so that power is wasted. The diameter of the rotary shaft and the cylindrical hole diameter of the sleeve
There are those in which the rotation shaft and the cylindrical hole of the sleeve are stepped in different stages in the axial direction (JP-A-6-159355, JP-A-6-173943, JP-A-10-281150). However, these publications do not mention bearing rigidity and axial loss torque in relation to bearing loads.

Further, in such a conventional hydrodynamic bearing device 01, the center of gravity of the entire rotating part including the rotating shaft 030 is the center axis of the rotating shaft 030 in a state where the disk is mounted on the disk mounting surface 04 of the rotor hub 03. It is at point Q near the upper center. Then, the weight F of the entire rotating unit is applied to this point Q as gravity, and this is a thrust in the direction of point R that acts on the rotating shaft 030 when the rotating shaft 030 maintains a vertical posture. Here, the point R is the lowest point on the central axis of the rotation shaft 030. On the other hand, the resultant force of the force that receives this thrust F (this force is generated in the dynamic pressure generating portion formed in the minute gap between the lower end surface of the thrust ring 060 and the upper surface of the counter plate 020). The position where T reacts to the rotation shaft 030 is at the point R, the direction is upward in the direction of the point Q, and is opposite to the thrust F. Therefore, the thrust F and the resultant force T cancel each other, and the rotation shaft 030 floats from the upper surface of the counter plate 020 and rotates without contact with the upper surface. Here, when the vertical posture of the rotating shaft 030 collapses for some reason, the direction in which the weight F of the entire rotating unit acts as gravity deviates from the point R direction,
It is inconsistent with the direction of resultant force T. As a result, a moment is generated on the rotating shaft 030 to cause the rotating shaft 030 to be tilted, the rotation of the rotating shaft 030 becomes unstable, and the rotation accuracy deteriorates. This rotating shaft 030
The moment for defeating becomes larger as the distance between the point Q and the point R becomes larger. Therefore, the position of the point R should be as close as possible to the position of the point Q.

Further, in such a conventional hydrodynamic bearing device 01, the thrust acting on the rotating shaft 030 is received by the counter plate 020. Therefore, the finishing accuracy of the counter plate 020 and this are assembled to the sleeve 010. If the assembly accuracy at that time is not sufficient, the parallel of the central axis of the rotating shaft 030 and the central axis of the sleeve 010 collapses,
The rotation of the rotation shaft 030 becomes unstable and the rotation accuracy is deteriorated.
JP-A-6-159355 Japanese Unexamined Patent Publication No. 6-173943 JP-A-10-281150

The invention of the present application solves the above-mentioned problems of the conventional hydrodynamic bearing device, reduces the shaft loss torque as much as possible while ensuring the bearing rigidity necessary for the rotating shaft with a relatively simple configuration. To provide a hydrodynamic bearing device capable of reducing power consumption, stabilizing the rotation of a rotary shaft, and further improving the rotational accuracy, a spindle motor including the hydrodynamic bearing device, and a recording disk drive device. Let it be an issue.

The invention of the present application relates to a hydrodynamic bearing device that has solved the above-described problems, a spindle motor including the hydrodynamic bearing device, and a recording disk drive device.
The invention described in claim 1 is formed by a cylindrical bearing case having a cylindrical hole in the center, an end plate closing one end of the bearing case, and the bearing case and the end plate. A shaft body that is supported by inserting at least a part thereof in the bearing container, wherein the cylindrical hole of the bearing case has a large diameter portion on the other end side of the bearing case; The bearing case has a stepped cylindrical hole having a small diameter portion on one end side of the bearing case. A stepped shaft body is provided, and a first dynamic pressure groove is formed on either the large diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large diameter portion of the stepped shaft body. Either the small diameter part of the cylindrical hole or the outer peripheral surface of the small diameter part of the stepped shaft body The second dynamic pressure groove is formed, and the third dynamic pressure groove is formed on either the inner surface of the end plate or the end surface on the one end portion side of the stepped shaft body. Fluid, lubricating oil for generating dynamic pressure is filled in the minute gaps between the opposing surfaces facing the second dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove, respectively. It is a bearing device.

Since the invention described in claim 1 is configured as described above, when viewed in the axial direction of the bearing case and the shaft body, the bearing case is located on the opposite side to the side closed by the end plate.
A large-diameter radial dynamic pressure bearing portion is formed in the minute gap portion facing the dynamic pressure groove, and a small diameter portion is formed in the minute gap portion facing the second dynamic pressure groove on the side where the bearing case is closed by the end plate. A radial dynamic pressure bearing portion is formed, and an axial dynamic pressure bearing portion is formed in a minute gap portion where the third dynamic pressure groove faces where the end plate and one end portion of the shaft face each other.

For this reason, a relatively high bearing rigidity is required by connecting a load member (rotating body or fixed body) such as a rotor hub to the end of the shaft body, on the side opposite to the side where the bearing case is closed by the end plate. A large-diameter radial dynamic pressure bearing part is set on the one half side of the shaft body, and relatively low bearing rigidity is required. On the other half part side of the shaft body located on the side where the bearing case is closed by the end plate, A small-diameter radial dynamic pressure bearing part can be set, and in this small-diameter radial dynamic pressure bearing part, the friction loss can be reduced and the shaft loss torque can be reduced as a whole, Thus, with a simple configuration, it is possible to reduce the shaft loss torque as much as possible and reduce the power consumption while ensuring the necessary bearing rigidity.
In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of tilting the shaft body can be reduced, and the moment vibration of the shaft body caused by this moment can be reduced. it can.

The invention described in claim 2 is formed by a cylindrical bearing case having a cylindrical hole in the center, an end plate closing one end of the bearing case, and the bearing case and the end plate. A shaft body supported by inserting at least a part of the shaft into the bearing container, wherein the cylindrical hole of the bearing case has a large diameter portion on the other end side of the bearing case And a small diameter portion on one end side of the bearing case, and the shaft body has a large diameter portion and a small diameter portion that face the large diameter portion and the small diameter portion of the stepped cylindrical hole, respectively. A first dynamic pressure groove is formed on either the large diameter portion of the stepped cylindrical hole and the outer peripheral surface of the large diameter portion of the stepped shaft body, Between the small diameter part of the stepped cylindrical hole and the outer peripheral surface of the small diameter part of the stepped shaft body In this, a second dynamic pressure groove is formed, and a third dynamic pressure groove is formed on either the step portion of the stepped cylindrical hole or the surface of the step portion of the stepped shaft body. In addition, a minute gap between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove is filled with lubricating oil for generating dynamic pressure. This is a fluid bearing device.

Since the invention described in claim 2 is configured as described above, when viewed in the axial direction of the bearing case and the shaft body, the bearing case is located on the opposite side to the side closed by the end plate.
A large-diameter radial dynamic pressure bearing portion is formed in the minute gap portion facing the dynamic pressure groove, and the small diameter portion is formed in the minute gap portion facing the second dynamic pressure groove on the side where the bearing case is closed by the end plate. A radial dynamic pressure bearing portion is formed, and an axial dynamic pressure is provided in a minute gap portion where the third dynamic pressure groove faces the step portion of the stepped cylindrical hole of the bearing case and the step portion of the stepped shaft body. A bearing part will be formed.

As a result, a relatively high bearing rigidity is required by connecting a load member (rotating body or fixed body) such as a rotor hub to the end of the shaft body. On the side opposite to the side where the bearing case is closed by the end plate A large-diameter radial dynamic pressure bearing part is set on one side of the shaft body located, and relatively low bearing rigidity is sufficient. On the other half part side of the shaft body located on the side where the bearing case is closed by the end plate, A small-diameter radial dynamic pressure bearing part can be set, and in this small-diameter radial dynamic pressure bearing part, the friction loss can be reduced and the shaft loss torque can be reduced as a whole. Thus, with a simple configuration, it is possible to reduce the shaft loss torque as much as possible and reduce power consumption while ensuring the required bearing rigidity.
In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of tilting the shaft body can be reduced, and the moment vibration of the shaft body caused by this moment can be reduced. it can.

In addition, the axial dynamic pressure bearing portion is positioned closer to the axial center of the shaft body, and the shaft body and the shaft body support the position where the resultant force of the thrust force acting on the shaft body reacts against the shaft body. Therefore, the rotation (relative rotation) of the shaft body can be stabilized and the rotation accuracy can be improved with a simple configuration.

Further, the axial dynamic pressure bearing portion is not provided in a minute gap between the inner surface of the end plate and the end surface on the one end portion side of the shaft body (in other words, thrust acting on the shaft body is received by the end plate). Therefore, depending on the finish accuracy of the end plate and the assembly accuracy when it is assembled to the bearing case, the parallelism between the center axis of the shaft body and the center axis of the bearing case may be lost. There is no possibility that the rotation (relative rotation) becomes unstable and the rotation accuracy deteriorates. Further, the surface hardness is increased by coating the upper surface of the end plate by sputtering or the like, so that it is not necessary to increase the sliding wear resistance with the rotating shaft at the time of starting and stopping.

Furthermore, the invention described in claim 3 is formed by a cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and the bearing case and the end plate. And a shaft body supported by inserting at least a part of the shaft into the bearing container, wherein the cylindrical hole of the bearing case has a large diameter portion on the other end side of the bearing case And a stepped cylindrical hole having a small diameter portion on one end side of the bearing case and a tapered portion connecting the large diameter portion and the small diameter portion, and the shaft body has a large diameter of the stepped cylindrical hole. A stepped shaft body having a large diameter portion, a small diameter portion, and a taper portion that are opposed to the portion, the small diameter portion, and the taper portion, respectively, and the large diameter portion of the stepped cylindrical hole and the large diameter portion of the stepped shaft body A first dynamic pressure groove is formed on any of the outer peripheral surfaces of A second dynamic pressure groove is formed on either the small diameter portion of the stepped cylindrical hole or the outer peripheral surface of the small diameter portion of the stepped shaft body, and the tapered portion of the stepped cylindrical hole and the stepped portion are formed. A third dynamic pressure groove is formed on any of the outer peripheral surfaces of the tapered portion of the shaft body, and the first
Fluid, lubricating oil for generating dynamic pressure is filled in the minute gaps between the opposing surfaces facing the second dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove, respectively. It is a bearing device.

Since the invention described in claim 3 is configured as described above, when viewed in the axial direction of the bearing case and the shaft body, the bearing case is located on the opposite side to the side closed by the end plate.
A large-diameter radial dynamic pressure bearing portion is formed in the minute gap portion facing the dynamic pressure groove, and the small diameter portion is formed in the minute gap portion facing the second dynamic pressure groove on the side where the bearing case is closed by the end plate. A radial axial bearing is formed in the radial gap in the minute gap where the third dynamic pressure groove faces where the tapered part of the stepped cylindrical hole of the bearing case and the tapered part of the stepped shaft body face each other. A dynamic pressure bearing portion is formed.

For this reason, a relatively high bearing rigidity is required by connecting a load member (rotating body or fixed body) such as a rotor hub to the end of the shaft body, on the side opposite to the side where the bearing case is closed by the end plate. A large-diameter radial dynamic pressure bearing part is set on the one half side of the shaft body, and relatively low bearing rigidity is required. On the other half part side of the shaft body located on the side where the bearing case is closed by the end plate, A small-diameter radial dynamic pressure bearing part can be set, and in this small-diameter radial dynamic pressure bearing part, the friction loss can be reduced and the shaft loss torque can be reduced as a whole, Thus, with a simple configuration, it is possible to reduce the shaft loss torque as much as possible and reduce the power consumption while ensuring the necessary bearing rigidity.
In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of tilting the shaft body can be reduced, and the moment vibration of the shaft body caused by this moment can be reduced. it can.

Also, the radial and axial dynamic pressure bearings are positioned closer to the axial center of the shaft body, and the position where the resultant force of the thrust force acting on the shaft body reacts against the shaft body is set on the shaft body and the shaft body. Since the center of gravity can be brought close to the overall position of the center of gravity combined with the load member to be supported, the rotation (relative rotation) of the shaft body can be stabilized and the rotation accuracy can be improved with a simple configuration.

Further, the axial dynamic pressure bearing portion is not provided in a minute gap between the inner surface of the end plate and the end surface on the one end portion side of the shaft body (in other words, thrust acting on the shaft body is received by the end plate). Therefore, depending on the finish accuracy of the end plate and the assembly accuracy when it is assembled to the bearing case, the parallelism between the center axis of the shaft body and the center axis of the bearing case may be lost. There is no possibility that the rotation (relative rotation) becomes unstable and the rotation accuracy deteriorates. Further, the surface hardness is increased by coating the upper surface of the end plate by sputtering or the like, so that it is not necessary to increase the sliding wear resistance with the rotating shaft at the time of starting and stopping.

Further, a radial and axial dynamic pressure bearing portion is formed in a minute gap portion where the third dynamic pressure groove faces the tapered portion of the stepped cylindrical hole of the bearing case and the tapered portion of the stepped shaft body. Therefore, also in this portion, the radial force acting on the shaft body can be shared and supported, and the necessary bearing rigidity can be further sufficiently ensured.

Further, by configuring the hydrodynamic bearing device according to any one of claims 1 to 3 as described in claim 4, an annular groove formed in a cylindrical hole of the bearing case and an outer peripheral surface of the shaft body An annular ring for preventing the shaft body from slipping out is inserted so as to straddle the annular groove formed in the shaft, so that the shaft body can be removed from the bearing container even if vibration or impact is applied to the fluid bearing device. There is no risk of getting out.

Further, by configuring the hydrodynamic bearing device according to any one of claims 1 to 3 as described in claim 5, a rotor hub constituting a rotating element is fitted to the upper end portion of the shaft body. The hydrodynamic bearing device has the following configuration. That is, an annular groove is formed on the outer peripheral surface of the upper end portion of the bearing case, and an annular ring having a width smaller than the width of the annular groove is fixed to the surface of the rotor hub facing the annular groove, The shaft body is provided so as to be positioned in the annular groove, thereby preventing the shaft body from coming off.

As a result, the annular ring for preventing the shaft body from coming off is provided outside the bearing case. Therefore, the axial length of the hydrodynamic bearing device is shortened by checking the bearing case by the amount of the annular ring. And assembly work becomes easy.

According to a sixth aspect of the present invention, there is provided a cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, the bearing case, and the end plate. A hydrodynamic bearing device comprising: a shaft body that is inserted and supported in at least a part of the bearing container; and a thrust ring that is fitted to one end of the shaft body. The hole has a large-diameter portion on the other end side of the bearing case, a small-diameter portion on one end portion side of the bearing case, an enlarged-diameter portion at one end portion of the bearing case for receiving the thrust ring, The shaft body is a stepped shaft body having a large diameter portion and a small diameter portion opposed to a large diameter portion and a small diameter portion of the stepped cylindrical hole, respectively, and the stepped cylindrical hole has the stepped cylindrical hole. Large diameter part of cylindrical hole and stepped A first dynamic pressure groove is formed on any one of the outer peripheral surfaces of the large-diameter portion of the body, and either the small-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the small-diameter portion of the stepped shaft body The second dynamic pressure groove is formed, and the third dynamic pressure groove is formed on either the inner surface of the end plate or the lower surface of the thrust ring, and the diameter-enlarged portion of the stepped cylindrical hole A fourth dynamic pressure groove is formed in any of the step portion connected to the upper surface of the thrust ring facing the step portion, and the first dynamic pressure groove, the second dynamic pressure groove, The hydrodynamic bearing device is characterized in that a minute gap between the opposing surfaces facing the third dynamic pressure groove and the fourth dynamic pressure groove is filled with lubricating oil for generating dynamic pressure.

Since the invention described in claim 6 is configured as described above, in addition to the invention described in claim 1, the hydrodynamic bearing device is a thrust ring fitted to one end of the shaft body. The cylindrical hole of the bearing case has an enlarged diameter portion at one end portion of the bearing case for receiving the thrust ring, and a third dynamic pressure is applied to either the inner surface of the end plate or the lower surface of the thrust ring. A groove is formed, and a fourth dynamic pressure groove is formed in either the step portion connected to the enlarged diameter portion of the cylindrical hole of the bearing case or the upper surface of the thrust ring facing the step portion.

As a result, another axial dynamic pressure bearing portion (in the small gap where the fourth dynamic pressure groove faces the fourth dynamic pressure groove facing the thrust ring and the step portion connected to the enlarged diameter portion of the stepped cylindrical hole of the bearing case) The second axial dynamic pressure bearing portion) is formed, and the force generated by the second axial dynamic pressure bearing portion is the axial motion formed in the minute gap portion where the third dynamic pressure groove faces. Pressure bearing (
Since the direction is opposite to the direction of the force generated by the first axial dynamic pressure bearing portion), that is, the force receiving the thrust acting on the shaft body, the gap between these two minute gap portions should be kept appropriately. When it is necessary to stabilize the relative rotation of the shaft body, the force generated by the second axial dynamic pressure bearing portion is combined with the force generated by the first axial dynamic pressure bearing portion. It can be used as a force to meet your needs. For example, when the electromagnetic force excited by the electromagnetic drive unit (motor) normally provided to rotate the shaft body and the bearing case relative to each other cannot be used as a force to meet such a need, The force generated in the second axial hydrodynamic bearing can also be used for that purpose.

Further, since the thrust ring is received in the enlarged diameter portion of the stepped cylindrical hole of the bearing case, there is no possibility that the shaft body comes out of the bearing container even if vibration or impact is applied to the hydrodynamic bearing device.
In addition, the same effects as the effects described in the first aspect can be obtained.

Furthermore, the invention described in claim 7 is formed by a cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and the bearing case and the end plate. A hydrodynamic bearing device comprising: a shaft body that is inserted and supported in at least a part of the bearing container; and a thrust ring that is fitted to one end of the shaft body. The hole has a large-diameter portion on the other end side of the bearing case, a small-diameter portion on one end portion side of the bearing case, an enlarged-diameter portion at one end portion of the bearing case for receiving the thrust ring, The shaft body is a stepped shaft body having a large diameter portion and a small diameter portion opposed to a large diameter portion and a small diameter portion of the stepped cylindrical hole, respectively, and the stepped cylindrical hole has the stepped cylindrical hole. Large diameter part of cylindrical hole and step A first dynamic pressure groove is formed on any of the outer peripheral surfaces of the large-diameter portion of the shaft body, and one of the small-diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small-diameter portion of the stepped shaft body. A second dynamic pressure groove is formed, and a third dynamic pressure groove is formed on either the step of the stepped cylindrical hole or the surface of the step of the stepped shaft body, A fourth dynamic pressure groove is formed in any one of the step portion connected to the enlarged diameter portion of the stepped cylindrical hole and the upper surface of the thrust ring facing the step portion, and the first dynamic pressure groove, A minute gap between the opposing surfaces facing the second dynamic pressure groove, the third dynamic pressure groove, and the fourth dynamic pressure groove is filled with lubricating oil for generating dynamic pressure. The hydrodynamic bearing device.

Since the invention described in claim 7 is configured as described above, in addition to the invention described in claim 2, the hydrodynamic bearing device is a thrust ring fitted to one end of the shaft body. The cylindrical hole of the bearing case has a diameter-enlarged portion at one end of the bearing case for receiving the thrust ring, and a step portion connected to the diameter-enlarged portion and an upper surface of the thrust ring facing the step portion In any case, a fourth dynamic pressure groove is formed.

As a result, another axial dynamic pressure bearing portion (in the small gap where the fourth dynamic pressure groove faces the fourth dynamic pressure groove facing the thrust ring and the step portion connected to the enlarged diameter portion of the stepped cylindrical hole of the bearing case) The second axial dynamic pressure bearing portion) is formed, and the force generated by the second axial dynamic pressure bearing portion is the axial motion formed in the minute gap portion where the third dynamic pressure groove faces. Pressure bearing (
Since the direction is opposite to the direction of the force generated by the first axial dynamic pressure bearing portion), that is, the force receiving the thrust acting on the shaft body, the gap between these two minute gap portions should be kept appropriately. When it is necessary to stabilize the relative rotation of the shaft body, the force generated by the second axial dynamic pressure bearing portion is combined with the force generated by the first axial dynamic pressure bearing portion. It can be used as a force to meet your needs. For example, when the electromagnetic force excited by the electromagnetic drive unit (motor) normally provided to rotate the shaft body and the bearing case relative to each other cannot be used as a force to meet such a need, The force generated in the second axial hydrodynamic bearing can also be used for that purpose.

Further, since the thrust ring is received in the enlarged diameter portion of the stepped cylindrical hole of the bearing case, there is no possibility that the shaft body comes out of the bearing container even if vibration or impact is applied to the hydrodynamic bearing device.
In addition, the same effects as the effects of the invention described in claim 2 can be obtained.

The invention described in claim 8 is formed by a cylindrical bearing case having a cylindrical hole in the center, an end plate closing one end of the bearing case, and the bearing case and the end plate. A hydrodynamic bearing device comprising: a shaft body that is inserted and supported in at least a part of the bearing container; and a thrust ring that is fitted to one end of the shaft body. The hole includes a large diameter portion on the other end side of the bearing case, a small diameter portion on one end portion side of the bearing case, a tapered portion connecting the large diameter portion and the small diameter portion, and one end portion of the bearing case. A stepped cylindrical hole having a diameter-enlarged portion for receiving the thrust ring, and the shaft body has a large diameter portion, a small-diameter portion, and a tapered portion respectively opposed to the large-diameter portion, the small-diameter portion, and the tapered portion. Diameter, small diameter and taper A first dynamic pressure groove is formed on either the large diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large diameter portion of the stepped shaft body. A second dynamic pressure groove is formed on either the small diameter portion of the stepped cylindrical hole or the outer peripheral surface of the small diameter portion of the stepped shaft body, and the taper portion of the stepped cylindrical hole and the stepped shaft body A third dynamic pressure groove is formed on any one of the outer peripheral surfaces of the taper portion, and any one of the stepped portion connected to the enlarged diameter portion of the stepped cylindrical hole and the upper surface of the thrust ring facing the stepped portion. In addition, a fourth dynamic pressure groove is formed, and each facing the first dynamic pressure groove, the second dynamic pressure groove, the third dynamic pressure groove, and the fourth dynamic pressure groove respectively. The hydrodynamic bearing device is characterized in that a minute gap between the surfaces is filled with lubricating oil for generating dynamic pressure.

Since the invention described in claim 8 is configured as described above, in addition to the invention described in claim 3, the hydrodynamic bearing device is a thrust ring fitted to one end of the shaft body. The cylindrical hole of the bearing case has a diameter-enlarged portion at one end of the bearing case for receiving the thrust ring, and a step portion connected to the diameter-enlarged portion and an upper surface of the thrust ring facing the step portion In any case, a fourth dynamic pressure groove is formed.

As a result, the axial dynamic pressure bearing portion is formed in the minute gap portion where the fourth dynamic pressure groove at the location where the step portion connected to the enlarged diameter portion of the stepped cylindrical hole of the bearing case and the thrust ring face each other faces. Thus, the force generated in the axial dynamic pressure bearing portion is the axial force generated in the radial axial dynamic pressure bearing portion formed in the minute gap portion where the third dynamic pressure groove faces, that is, the shaft This axial direction is opposite to the direction of the thrust force acting on the body, so it is necessary to stabilize the relative rotation of the shaft body by keeping the gap between these two minute gaps appropriate. The force generated in the dynamic pressure bearing portion can be used as a force to meet such a need, along with the axial force generated in the radial / axial dynamic pressure bearing portion. For example, when the electromagnetic force excited by the electromagnetic drive unit (motor) normally provided to rotate the shaft body and the bearing case relative to each other cannot be used as a force to meet such a need, The force generated in the axial dynamic pressure bearing can be used for that purpose.

Further, since the thrust ring is received in the enlarged diameter portion of the stepped cylindrical hole of the bearing case, there is no possibility that the shaft body comes out of the bearing container even if vibration or impact is applied to the hydrodynamic bearing device.
In addition, the same effect as that of the invention described in claim 3 can be obtained.

Furthermore, the invention described in claim 9 is a spindle motor including the hydrodynamic bearing device according to any one of claims 1 to 5, and is fitted to a stator and an upper end portion of a shaft body. A rotor hub that forms a rotating element, and a rotor magnet that is fitted to the rotor hub and generates a rotating magnetic field in cooperation with the stator, and is provided rotatably with respect to the housing, The hydrodynamic bearing device supports the rotation of the rotor, and the rotor acts in the direction in which the dynamic pressure generated in the dynamic pressure groove for generating the dynamic pressure that receives the axial load in the hydrodynamic bearing device acts. The spindle motor is attracted by a magnetic force in the opposite direction, and the load is supported by the balance between the dynamic pressure and the magnetic force.

Since the invention described in claim 9 is configured as described above, the hydrodynamic bearing device according to any one of claims 1 to 5 can achieve the respective effects, and the magnetic force is applied to these fluids. Appropriate clearance in the minute gap facing the dynamic pressure groove is balanced with the dynamic pressure generated in the dynamic pressure groove (third dynamic pressure groove) for generating the dynamic pressure that receives the axial load in the bearing device Thus, the relative rotation of the shaft body can be stabilized, and a spindle motor with low power consumption and high reliability can be obtained.

According to a tenth aspect of the present invention, there is provided a spindle motor comprising the hydrodynamic bearing device according to any one of the sixth to eighth aspects, wherein the spindle motor is fitted to the upper end portion of the stator and the shaft body. A rotor hub that forms a rotating element, and a rotor magnet that is fitted to the rotor hub and generates a rotating magnetic field in cooperation with the stator, and is provided rotatably with respect to the housing, The hydrodynamic bearing device is a spindle motor that supports the rotation of the rotor.

Since the invention described in claim 10 is configured as described above, the hydrodynamic bearing device according to any one of claims 6 to 8 can achieve the respective effects, power consumption is low, and reliability is achieved. High spindle motor can be obtained.

According to an eleventh aspect of the present invention, there is provided a recording disk drive device comprising the spindle motor according to the ninth or tenth aspect, wherein the recording disk is a recording disk for writing and / or reading information on the recording disk. A recording disk drive apparatus comprising a head, wherein a spindle motor rotationally drives the recording disk.

Since the invention described in claim 11 is configured as described above, the spindle motor according to claim 9 or 10 can achieve the respective effects, the power consumption is small, and the reliability is high. A high recording disk drive can be obtained.

As described above, according to the hydrodynamic bearing device of the invention of the present application, a large-diameter radial dynamic pressure bearing is provided in the minute gap portion where the first dynamic pressure groove faces the bearing case on the side opposite to the side closed by the end plate. Is formed in the minute gap where the second dynamic pressure groove on the side where the bearing case is closed by the end plate faces, so that the rotor hub or the like is formed at the end of the shaft body. The load member (rotating body or fixed body) is connected to the shaft body, and relatively high bearing rigidity is required. A radial dynamic pressure bearing with a small diameter is set, and a relatively low bearing rigidity is required. A small diameter radial dynamic pressure bearing is set on the other half of the shaft body located on the side where the bearing case is closed by the end plate. Can this In the radial dynamic pressure bearing portion in the radial, minute, which is a small diameter,
Since the shaft loss torque can be reduced by reducing the friction loss, the shaft loss torque can be reduced as much as possible by reducing the shaft loss torque as much as possible while ensuring the required bearing rigidity with a simple structure as a whole. Can do.
In addition, since the friction loss can be reduced in the small-diameter radial dynamic pressure bearing portion, the moment acting in the direction of tilting the shaft body can be reduced, and the moment vibration of the shaft body caused by this moment can be reduced. it can.

In addition, when the axial dynamic pressure bearing portion is formed in the minute gap portion where the third dynamic pressure groove faces the step portion of the stepped cylindrical hole of the bearing case and the step portion of the stepped shaft body. Is a position where the axial dynamic pressure bearing is located near the center of the shaft body, and the position where the resultant force of the thrust force acting on the shaft body reacts against the shaft body is a load connected to the shaft body and the shaft body. Since the center of gravity can be brought close to the overall center of gravity combined with the members, the rotation (relative rotation) of the shaft body can be stabilized and the rotation accuracy can be improved with a simple configuration.

Further, in this case, the axial dynamic pressure bearing portion is not provided in a minute gap between the inner surface of the end plate and the end surface on one end side of the shaft body (in other words, the thrust acting on the shaft body is not at the end). The center axis of the shaft body and the center axis of the bearing case are not parallel to each other depending on the finishing accuracy of the end plate and the assembly accuracy when it is assembled to the bearing case. Rotation of the body (relative rotation) does not become unstable and rotation accuracy does not deteriorate. Further, the surface hardness is increased by coating the upper surface of the end plate by sputtering or the like, so that it is not necessary to increase the sliding wear resistance with the rotating shaft at the time of starting and stopping.

Further, a thrust ring is fitted to one end portion of the shaft body, and a diameter-enlarged portion for receiving the thrust ring is formed in the cylindrical hole of the bearing case and is disposed at one end portion of the bearing case. In the case where the fourth dynamic pressure groove is formed in any one of the upper portion and the upper surface of the thrust ring facing the stepped portion, the axial dynamic pressure bearing portion is formed in the minute gap portion where the fourth dynamic pressure groove faces. When it is necessary to stabilize the relative rotation of the shaft body by appropriately maintaining the gaps between both the minute gaps facing the third dynamic pressure groove and the fourth dynamic pressure groove, respectively. The force generated by the axial dynamic pressure bearing is required along with the force generated by the axial dynamic pressure bearing or the radial / axial dynamic pressure bearing formed in the minute gap facing the third dynamic pressure groove. Can be used as a response force .

Furthermore, a spindle motor equipped with a hydrodynamic bearing device that exhibits various effects as described above and a recording disk drive device equipped with the spindle motor can reduce the power consumption and provide a highly reliable spindle motor and recording. A disk drive device can be obtained.

A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and at least a part thereof is fitted into a bearing container formed by the bearing case and the end plate. A cylindrical hole of the bearing case is formed into a stepped cylindrical hole including a large diameter portion on the other end side of the bearing case and a small diameter portion on the one end side. The shaft body is composed of a stepped shaft body composed of a large diameter portion and a small diameter portion facing the large diameter portion and the small diameter portion of the stepped cylindrical hole, respectively, and the large diameter portion of the stepped cylindrical hole is formed. A first dynamic pressure groove is formed on either the outer peripheral surface of the stepped shaft body or the large diameter portion of the stepped shaft body, and either the small diameter portion of the stepped cylindrical hole or the outer peripheral surface of the small diameter portion of the stepped shaft body A second dynamic pressure groove is formed, preferably a stepped portion or tapered portion of a stepped cylindrical hole and a stepped shaft body. Alternatively, a third dynamic pressure groove is formed either on the surface of the taper portion, and the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove respectively face each other and face each other. Fill the gap with lubricating oil for generating dynamic pressure.
If necessary, in addition to the above-described configuration, a thrust ring is fitted to one end of the shaft body, and the cylindrical hole of the bearing case is extended to receive the thrust ring at one end of the bearing case. A diameter portion is formed, and a fourth dynamic pressure groove is formed on either the step portion connected to the enlarged diameter portion or the upper surface of the thrust ring facing the step portion.

Next, a first embodiment (embodiment 1) of the present invention will be described.
1 is a longitudinal sectional view of a hydrodynamic bearing device according to a first embodiment. In FIG. 1, a hydrodynamic bearing device 1 includes a cylindrical bearing case 10 having a cylindrical hole 11 (11a, 11b) in the center, an end plate 20 that closes one end of the bearing case 10 in FIG. A shaft body 30 is provided that is supported by being fitted at least partially in a bearing container formed by the bearing case 10 and the end plate 20. The shaft body 30 is connected to a load rotating body (not shown).
In some cases, it is manufactured from the beginning as an integral part of the rotating shaft of the rotating body. In addition, a fixed body may be connected to the shaft body 30 instead of the rotating body. In this case, the bearing case 10 is on the rotation side. In the present specification, the side where one end of the bearing case 10 is closed by the end plate 20 is defined as the lower side, and the opening side of the bearing container is defined as the upper side.

The cylindrical hole 11 of the bearing case 10 is stepped with a large-diameter portion 11 a formed on the other end portion side above the bearing case 10 and a small-diameter portion 11 b formed on one end portion side below the bearing case 10. The shaft body 30 is configured as a stepped shaft body having a large diameter portion 31a and a small diameter portion 31b respectively facing the large diameter portion 11a and the small diameter portion 11b of the stepped cylindrical hole 11. It is configured. A first dynamic pressure groove 51 is formed in the large diameter portion 11 a of the stepped cylindrical hole 11, and a second dynamic pressure groove 52 is formed in the small diameter portion 11 b of the stepped cylindrical hole 11. Further, a third dynamic pressure groove 53 is formed on the inner surface 21 of the end plate 20.

These dynamic pressure grooves 51 to 53 are formed in a herringbone shape, but are not necessarily limited to this shape, and may be formed in a spiral shape or a linear shape. In addition, the first dynamic pressure groove 51,
The second dynamic pressure groove 52 and the third dynamic pressure groove 53 are formed on the outer peripheral surface of the large-diameter portion 31a of the stepped shaft body 30, the outer peripheral surface of the small-diameter portion 31b, and the end surface (lower end surface) 33 on one end side. Each may be formed. Between the large diameter part 11a and the small diameter part 11b of the stepped cylindrical hole 11, the step part 11 perpendicular to the hole surface is provided.
c. Between the large diameter part 31a and the small diameter part 31b of the stepped shaft body 30, a step part 31c perpendicular to the outer surface thereof is formed.

The first dynamic pressure groove 51 includes a large diameter portion 11 a of the stepped cylindrical hole 11 and a large diameter portion 31 of the stepped shaft body 30.
It faces a minute gap formed between the outer peripheral surface of a and the minute gap is filled with lubricating oil for generating dynamic pressure. Further, the second dynamic pressure groove 52 faces a minute gap formed between the small diameter portion 11b of the stepped cylindrical hole 11 and the small diameter portion 31b of the stepped shaft body 30, and the minute gap includes Filled with lubricating oil for generating dynamic pressure. Further, the third dynamic pressure groove 53 faces a minute gap formed between the inner surface 21 of the end plate 20 and the lower end surface 33 of the stepped shaft body 30. Filled with lubricating oil for generation.

Further, the annular concave groove 12 formed in the small diameter portion 11b of the stepped cylindrical hole 11 of the bearing case 10 and the annular concave groove 32 formed on the outer peripheral surface of the small diameter portion 31b of the stepped shaft body 30 are straddled. Thus, the annular ring 40 for preventing the shaft body 30 from being detached is inserted. This annular ring 40
Prevents the shaft body 30 from coming out of the bearing container when vibration or impact is applied to the hydrodynamic bearing device 1.

The first dynamic pressure groove 51 faces the small gap formed between the large diameter portion 11a of the stepped cylindrical hole 11 and the outer peripheral surface of the large diameter portion 31a of the stepped shaft body 30, The gap portion formed on the outer open end side has a large diameter portion 11a slightly enlarged in diameter so as to be slightly larger than the minute gap, and a lubricating oil seal portion 13 is formed there. ing. First dynamic pressure groove 51
Since the lubricating oil for generating dynamic pressure filled in the micro gap facing the surface is blocked from capillary action at the widened seal portion 13, it does not leak from the micro gap portion to the outside open end side. .

The shaft 30 rotates relative to the gravity (self-weight) acting on itself, the gravity acting on a load member (not shown) supported by the shaft 30 (rotor hub, disk, etc.), and the shaft 30 and the bearing case 10. The end plate 20 is always pressed in a certain direction (downward in FIG. 1) by an electromagnetic force excited by an electromagnetic driving unit (motor) (not shown) provided for the purpose, and this is a force in the axial direction (thrust). Is acting as. Hydrodynamic bearing device 1
However, even when the shaft body 30 is used upside down, that is, when the shaft body 30 is positioned downward and the end plate 20 is positioned upward, the shaft body 30 is always subjected to the end plate by the electromagnetic force described above. 20 is pressed in a certain direction.

Since the first embodiment is configured as described above, the following operations and effects can be achieved.
Now, when an unillustrated electromagnetic drive unit (motor) provided to rotate the shaft body 30 and the bearing case 10 relative to each other operates, the shaft body 30 rotates relative to the bearing case 10.
Due to the action of the dynamic pressure grooves 51 and the second dynamic pressure grooves 52, the pressure of the lubricating oil is reduced in the minute gap portions (first and second radial dynamic pressure bearing portions) between the facing surfaces where the grooves face each other. The shaft body 30 is lifted and floated from the stepped cylindrical hole 11 of the bearing case 10. In this way, the shaft body 30
A radial force acting on the shaft body 30 is received by the stepped cylindrical hole 11, and the shaft body 30 rotates without contact with the stepped cylindrical hole 11.

Since the minute gap portion (first radial dynamic pressure bearing portion) facing the first dynamic pressure groove 51 has a large diameter, a large bearing rigidity can be exhibited, and a load connected to the upper end of the shaft body 30. It is suitable for stably rotating and supporting a member (such as a rotor hub). On the other hand, since the minute gap portion (second radial dynamic pressure bearing portion) where the second dynamic pressure groove 52 faces has a small diameter, the bearing rigidity is larger than that of the first radial dynamic pressure bearing portion. However, the rotation support of the load member connected to the upper end of the shaft body 30 is mainly performed by the first radial dynamic pressure bearing portion. Therefore, the second radial dynamic pressure bearing portion is reduced in diameter. Therefore, the friction loss can be reduced and the shaft loss torque can be reduced accordingly. Thus, with a simple configuration, it is possible to reduce the shaft loss torque as much as possible and reduce power consumption while ensuring the required bearing rigidity.
Further, the friction loss is reduced in the second radial dynamic pressure bearing portion, so that the shaft body 30 can be reduced.
The moment acting in the direction of tilting the shaft body 30 can be reduced, and the moment vibration of the shaft body 30 due to this moment (the swing vibration caused by the gyro of the shaft body 30) can also be reduced.

When the shaft body 30 rotates relative to the bearing case 10, the pressure of the lubricating oil rises in the minute gap portion (axial dynamic pressure bearing portion) where the groove faces due to the action of the third dynamic pressure groove 53. The shaft body 30 is levitated from the end plate 20. In this way, axial force (thrust) acting on the shaft body 30 is received by the inner surface 21 of the end plate 20, and the shaft body 30 rotates without contact with the end plate 20.

FIG. 2 is a longitudinal sectional view of a hydrodynamic bearing device according to a second embodiment (embodiment 2) of the present invention, in which parts corresponding to those in the embodiment 1 are denoted by the same reference numerals.
As illustrated in FIG. 2, the hydrodynamic bearing device 1 according to the second embodiment is different from the first embodiment only in the position where the third dynamic pressure groove 53 is formed. That is, in Example 1,
Although the third dynamic pressure groove 53 is formed on the inner surface 21 of the end plate 20, in the second embodiment, the third dynamic pressure groove 53 is a step portion of the stepped cylindrical hole 11 of the bearing case 10. 11c. Then, the lubricating oil is filled in the minute gap portion formed between the step portion 11c of the stepped cylindrical hole 11 and the outer surface of the step portion 31c of the stepped shaft body 30 facing the third dynamic pressure groove 53. Thus, an axial dynamic pressure bearing portion is formed here. The third dynamic pressure groove 53 may be modified so as to be formed on the outer surface of the step portion 31 c of the stepped shaft body 30.

Since Example 2 is configured as described above, the following operations and effects can be achieved.
Now, when an electromagnetic drive unit (motor) (not shown) is operated and the shaft body 30 rotates relative to the bearing case 10, a minute gap portion (axial motion) facing this groove is acted by the action of the third dynamic pressure groove 53. The pressure of the lubricating oil rises in the pressure bearing portion), and the shaft body 30 is replaced with the step portion 1 of the bearing case 10.
Lift from 1c. In this manner, axial force (thrust) acting on the shaft body 30 is received by the step portion 11c of the bearing case 10, and the shaft body 30 rotates without contact with the step portion 11c.

As a result, the axial dynamic pressure bearing portion is positioned closer to the center portion of the shaft body 30, and the position where the resultant force of the force receiving the thrust acting on the shaft body 30 counteracts the shaft body 30 is determined as the shaft body 30 and the shaft body. Since the center of gravity of the entire load member (rotor hub, disk, etc.) supported by 30 can be brought close to the center of gravity, the rotation of the shaft body 30 can be stabilized and the rotation accuracy can be improved with a simple configuration. it can.

Further, the axial dynamic pressure bearing portion is not provided in the minute gap portion between the inner surface 21 of the end plate 20 and the end surface (the lower end surface in FIG. 2) 33 on the one end portion side of the shaft body 30 (in other words, The thrust acting on the shaft body 30 is not received by the end plate 20). Therefore, depending on the finishing accuracy of the end plate 20 and the mounting accuracy when the end plate 20 is assembled to the bearing case 10, The parallelism between the central axis and the central axis of the bearing case 10 is broken.
The rotation of the shaft body 30 does not become unstable and the rotation accuracy does not deteriorate. Further, by increasing the surface hardness by coating the upper surface of the end plate 20 by sputtering or the like, it is not necessary to increase the sliding wear resistance with the rotating shaft at the time of starting and stopping.
In addition, the same effects as those of the first embodiment can be obtained with respect to the bearing rigidity, the shaft loss torque, and the moment vibration of the shaft body 30.

FIG. 3 is a longitudinal sectional view of a hydrodynamic bearing device according to a third embodiment (embodiment 3) of the present invention. Parts corresponding to those in the embodiment 2 are denoted by the same reference numerals.
As illustrated in FIG. 3, the hydrodynamic bearing device 1 of the third embodiment is different from the second embodiment in the step 11 c of the stepped cylindrical hole 11 of the bearing case 10 and the step 31 c of the stepped shaft body 30. And the tapered portion 11f of the stepped cylindrical hole 11 is formed with a third dynamic pressure groove 53, and the annular ring 40 is tapered.
Is different in that it is moved to the large diameter portion side of the bearing case 10 and the stepped shaft body 30. The third dynamic pressure groove 53 may be modified so as to be formed on the outer surface of the tapered portion 31 f of the stepped shaft body 30.

Therefore, in the third embodiment, the tapered portion 11f of the stepped cylindrical hole 11 of the bearing case 10 facing the third dynamic pressure groove 53 and the tapered portion of the stepped shaft body 30 formed to face the tapered portion 11f. A minute gap portion formed between the outer surface of 31f is filled with lubricating oil, and a radial / axial dynamic pressure bearing portion is formed here. In the radial / axial dynamic pressure bearing portion, an axial force (thrust) acting on the shaft body 30 is received, and a part of the radial force acting on the shaft body 30 is also received.

Since Example 3 is configured as described above, the following operations and effects can be achieved.
Now, when an electromagnetic drive unit (motor) (not shown) is operated and the shaft body 30 rotates relative to the bearing case 10, these grooves are exposed by the functions of the first to third dynamic pressure grooves 51 to 53. The pressure of the lubricating oil rises in the minute gap portions (first and second radial dynamic pressure bearing portions, radial and axial dynamic pressure bearing portions), and the shaft body 30 has a large diameter of the stepped cylindrical hole 11 of the bearing case 10. Part 11
a, levitated from the small diameter portion 11b and the tapered portion 11f. As a result, a radial force acting on the shaft body 30 is received by these portions of the stepped cylindrical hole 11, and an axial force (thrust) acting on the shaft body 30 is a tapered portion of the stepped cylindrical hole 11. 11f. The shaft body 30 rotates without contact with these portions.

In this way, the radial force acting on the shaft body 30 can be received even by the tapered portion 11f of the stepped cylindrical hole 11, so that the necessary bearing rigidity can be secured and the shaft can be as much as possible. Loss torque can be reduced and power consumption can be reduced.

Further, since the installation position of the annular ring 40 is moved to the outer end side of the large diameter portion of the bearing case 10 and the stepped shaft body 30, the annular ring 40 can be easily attached and the lubricating oil seal can be provided. The effect can be enhanced.
In addition, the same effects as those of the second embodiment can be obtained with respect to bearing rigidity, moment vibration of the shaft body 30, rotational accuracy of the shaft body 30, and the like.

In the third embodiment, the tapered portion 11f of the stepped cylindrical hole 11 or the stepped shaft 3
When the width of the outer surface of the 0 taper portion 31f is narrow and it is difficult to form the third dynamic pressure groove 53 here, the third dynamic pressure groove 53 is the same as in the first embodiment. In other words, it is formed on the inner surface 21 of the end plate 20 or the lower end surface 33 of the stepped shaft 30.

The first to third embodiments (embodiments 1 to 3) of the present invention described above are preferably used when electromagnetic force is acting so as to constantly press the shaft body 30 against the end plate 20. Fluid bearing device. In a hydrodynamic bearing device, when such electromagnetic force is not expected,
There is a risk that the relative rotating part will float and its rotation will become unstable. Examples 4 to 6 described below
The present invention relates to a hydrodynamic bearing device including a hydrodynamic bearing portion that can exert an axial force in place of such an electromagnetic force.

FIG. 4 is a longitudinal sectional view of a hydrodynamic bearing device according to a fourth embodiment (Embodiment 4) of the present invention. The parts corresponding to those in Embodiment 1 are denoted by the same reference numerals.
As shown in FIG. 4, the hydrodynamic bearing device 1 of the fourth embodiment further includes a thrust ring 60 fitted to one end portion of the shaft body 30 as compared with the first embodiment. The attached cylindrical hole 11 has an enlarged diameter portion 11d at one end portion of the bearing case 10 for receiving the thrust ring 60, and a fourth dynamic pressure groove 54 is formed in a step portion 11e connected to the enlarged diameter portion 11d. Yes. The fourth dynamic pressure groove 54 is formed on the upper surface 61 of the thrust ring 60 facing the step portion 11e.
May be formed.

Further, in the first embodiment, the inner surface 21 of the end plate 20 facing the third dynamic pressure groove 53.
In this embodiment, the axial dynamic pressure bearing portion formed in the minute gap between the lower end surface 33 of the stepped shaft body 30 and the lower surface 62 of the thrust ring 60 is the inner surface 21 of the end plate 20. It has been moved to the minute gap between. Therefore, in the fourth embodiment, the third
The dynamic pressure groove 53 is formed on the inner surface 21 of the end plate 20 facing the lower surface 62 of the thrust ring 60 or on the lower surface 62 of the thrust ring 60. Furthermore, the annular ring 40 for preventing the shaft body 30 from being detached in the first embodiment is abolished in the fourth embodiment.
The other points are not different from those of the first embodiment, and detailed description thereof is omitted.

Since the fourth embodiment is configured as described above, the step portion 11e where the fourth dynamic pressure groove 54 faces is provided.
Another axial dynamic pressure bearing portion (second axial dynamic pressure bearing portion) is formed in a minute gap portion formed at a position where the upper surface 61 of the thrust ring 60 and the thrust ring 60 face each other. The force generated in the axial dynamic pressure bearing portion is the force generated in the axial dynamic pressure bearing portion (first axial dynamic pressure bearing portion) formed in the minute gap portion where the third dynamic pressure groove 53 faces, That is, since it faces in the direction opposite to the direction of the force that receives the thrust acting on the shaft body 30, the shaft body 30
Is always pressed against the end plate 20. As a result, the relative rotating portion (in the case of the fourth embodiment, the shaft body 30 and the load member supported by the shaft body 30) are prevented from floating, and the third and fourth
The gaps between these minute gaps facing the respective dynamic pressure grooves 53 and 54 are appropriately maintained, and the shaft body 30
The relative rotation of the can be stabilized.

Further, since the thrust ring 60 is received in the enlarged diameter portion 11d of the stepped cylindrical hole 11 of the bearing case 10, the shaft body 30 may come out of the bearing container even if vibration or impact is applied to the hydrodynamic bearing device 1. Absent.
In addition, the same effects as those of the first embodiment can be obtained.

FIG. 5 is a longitudinal sectional view of a hydrodynamic bearing device according to a fifth embodiment (Embodiment 5) of the present invention. Parts corresponding to those in Embodiments 2 and 4 are denoted by the same reference numerals. .
As illustrated in FIG. 5, the hydrodynamic bearing device 1 of the fifth embodiment further includes a thrust ring 60 fitted to one end portion of the shaft body 30 as compared with the second embodiment. The attached cylindrical hole 11 has an enlarged diameter portion 11d at one end portion of the bearing case 10 for receiving the thrust ring 60, and a fourth dynamic pressure groove 54 is formed in a step portion 11e connected to the enlarged diameter portion 11d. Yes. The fourth dynamic pressure groove 54 is formed on the upper surface 61 of the thrust ring 60 facing the step portion 11e.
May be formed. Further, the annular ring 40 for preventing the shaft body 30 from being detached in the second embodiment is abolished in the fifth embodiment.
The other points are not different from those of the second embodiment, and detailed description thereof is omitted.

Since the fifth embodiment is configured as described above, the step portion 11e where the fourth dynamic pressure groove 54 faces is provided.
Another axial dynamic pressure bearing portion (second axial dynamic pressure bearing portion) is formed in a minute gap portion formed at a position where the upper surface 61 of the thrust ring 60 and the thrust ring 60 face each other. The first axial dynamic pressure bearing portion is formed at a different location from that of the first embodiment, but the same effect as the floating prevention effect of the relative rotation portion of the fourth embodiment can be obtained. Further, similarly to the fourth embodiment, there is no possibility that the shaft body 30 comes out of the bearing container due to vibration or impact.
In addition, the second embodiment except for the effect of preventing the shaft body 30 produced by the annular ring 40 from being prevented from coming off.
The same effect can be achieved.

FIG. 6 is a longitudinal sectional view of a hydrodynamic bearing device according to a sixth embodiment (embodiment 6) of the present invention. Parts corresponding to those in the third and fifth embodiments are denoted by the same reference numerals. .
As illustrated in FIG. 6, the hydrodynamic bearing device 1 of the sixth embodiment is different from the third embodiment in the second embodiment.
A second axial dynamic pressure bearing portion corresponding to the axial dynamic pressure bearing portion is added, and the annular ring 40 of the third embodiment is eliminated.
The other points are not different from those of the third embodiment, and detailed description thereof is omitted.

Since the sixth embodiment is configured as described above, the step portion 11e where the fourth dynamic pressure groove 54 faces is provided.
Another axial dynamic pressure bearing portion (second axial dynamic pressure bearing portion) is formed in a minute gap portion formed at a position where the upper surface 61 of the thrust ring 60 and the thrust ring 60 face each other. In comparison with the first axial dynamic pressure bearing portion or the radial axial dynamic pressure bearing portion, the outer surface of the stepped portion 11c of the stepped cylindrical hole 11 and the stepped portion 31c of the stepped shaft body 30 is formed. Or a minute gap formed between the tapered portion 11f of the stepped cylindrical hole 11 and the outer surface of the tapered portion 31f of the stepped shaft body 30. Although it is different in point, the same effect as the floating prevention effect of the relative rotation part of the fifth embodiment can be obtained. Also,
Similar to the fifth embodiment, there is no possibility that the shaft body 30 comes out of the bearing container due to vibration or impact.
Other than that, the third embodiment except for the effect of preventing the shaft body 30 played by the annular ring 40 from being removed.
The same effect can be achieved.

FIG. 7 is a longitudinal sectional view of a spindle motor according to a seventh embodiment (embodiment 7) of the present invention. This spindle motor includes a hydrodynamic bearing device having the same basic structure as the hydrodynamic bearing device 1 (see FIG. 2) of the second embodiment. Therefore, in the following, the same reference numerals are given to the parts corresponding to those of the hydrodynamic bearing device 1 of the second embodiment, and the detailed overlapping description is omitted.

As shown in FIG. 7, the spindle motor 70 of the seventh embodiment has a cylindrical shape of a base 71 (the base 71 also serves as a part of a case of a recording disk drive device 80 described later). In the central circular hole of the wall 76, the bearing case 10 of the hydrodynamic bearing device 1 is fitted and fixed,
A shaft rotation type spindle motor is configured. The cylindrical wall 76 is formed so as to protrude upward from the bottom at a substantially central position in the figure of the bottom of the base 71.

At the upper end portion of the stepped shaft body 30 of the hydrodynamic bearing device 1, a rotating element of the spindle motor 70 is formed, and a bowl-shaped rotor hub 72 having a shallow overall shape has a stepped central opening in a posture in which the dish is turned down. The large-diameter portion is fixed to the upper end portion of the stepped shaft body 30 so that the rotor hub 72 can rotate integrally with the stepped shaft body 30.

A cylindrical wall 72a projects downward from the central opening of the rotor hub 72 slightly outward in the radial direction. The lower end portion of the inner peripheral surface of the cylindrical wall 72a is enlarged in diameter, and the enlarged diameter portion 72b is formed there. A retaining ring 78 is fitted on the inner peripheral surface of the enlarged diameter portion 72b. The retaining ring 78 includes a stepped shaft body 30 and a rotor hub 72.
Is provided to prevent the rotating body (rotor assembly) made of
Details of the operation will be described later.

An annular groove 14 having a width larger than the width of the retaining ring 78 is formed on the outer peripheral surface of the bearing case 10 facing the enlarged diameter portion 72b. The inner peripheral portion of the retaining ring 78 described above is
The ring-shaped groove 14 extends to the inside without contacting the ring-shaped groove 14. Therefore, even if the rotating body is subjected to a strong shock or vibration during rotation or when rotation is stopped, the inner peripheral portion of the retaining ring 78 comes into contact with the ceiling surface of the annular groove 14, The slip-off preventing ring 78 can prevent the slip-off, and the retaining ring 78 plays a role of preventing the slip-off without inhibiting the rotation of the rotating body. Thus, by providing the retaining ring 78 on the outer side of the bearing case 10, the axial length of the bearing case 10 can be shortened by the width of the retaining ring 78, and the assembling operation can be performed. Will also be easier.

On the outer peripheral surface of the rotor hub 72, information recording media (recording disks) such as a magnetic disk and an optical disk (not shown) are mounted in a plurality of stages. Although not shown in detail in the upper end portion of the stepped shaft body 30, a tap hole is formed, and a clamp member that presses and fixes these information recording media from above is screwed to the tap hole. Thus, it is fixed to the stepped shaft 30.

A stator 73 formed by winding a coil around a stator core is fitted on the outer peripheral surface of the cylindrical wall 76 of the base 71, and the permanent magnet 74 attaches the stator 73 with a slight radial gap therebetween. It arrange | positions in the circumferential direction so that it may surround, and is attached to the internal peripheral surface of the surrounding wall of the rotor hub 72. FIG. As described above, in order to obtain a structure in which the permanent magnet 74 is directly attached to the rotor hub 72 without using the yoke, the rotor hub 72 needs to be made of a magnetic material.
For this purpose, applicable magnetic materials include, for example, martensitic or ferritic stainless alloys. On the other hand, when the rotor hub 72 is made of a nonmagnetic material such as an aluminum alloy, a ring-shaped yoke made of a magnetic material is used as the rotor hub 72 and the permanent magnet 74.
It is necessary to intervene between.

A flexible wiring board 75 is fixed to the lower surface of the base 71, and this wiring board 7
When the control current is supplied to the stator 73 from the output terminal 5, the rotor assembly (rotating body) including the permanent magnet 74, the rotor hub 72, the stepped shaft body 30, and the like starts rotating with respect to the stator 73.

In the seventh embodiment, an annular suction plate 77 is fixed to the bottom surface of the base 71 directly under the permanent magnet 74 in order to balance the load in the thrust direction when the rotor assembly rotates. Thus, a magnetic force having the same magnitude as the resultant force of the force acts in a direction opposite to the direction of the resultant force of the dynamic pressure generated by the third dynamic pressure groove 53. In this way, the suction plate 77 acts to attract the permanent magnet 74, so that the rotor assembly can be stably supported by the shaft with the stepped shaft 30.

Since the seventh embodiment is configured as described above, the seventh embodiment can achieve the same effect as the fluid bearing device 1 of the second embodiment, and works between the suction plate 77 and the permanent magnet 74. By the action of the magnetic force, it is possible to stabilize the relative rotation of the rotor assembly by checking the stepped shaft 30, and the spindle motor 70 with low power loss and high reliability can be obtained.
In addition, instead of the hydrodynamic bearing device 1 of the second embodiment, the hydrodynamic bearing device 1 of the first and third embodiments or a modified example thereof can be applied to the spindle motor 70 of the seventh embodiment.

FIG. 8 is a longitudinal sectional view of a spindle motor according to an eighth embodiment (Embodiment 8) of the present invention. As is apparent from FIG. 8, the spindle motor 70 of the eighth embodiment is different from the spindle motor 70 of the seventh embodiment in that the hydrodynamic bearing device 1 is the hydrodynamic bearing device 1 (fourth embodiment). (See FIG. 4), and accompanying this, the retaining ring 78
And the related structure and the suction plate 77 are omitted, but there is no difference in other points. Therefore, in the following, the same reference numerals are given to the portions corresponding to the spindle motor 70 of the seventh embodiment and the hydrodynamic bearing device 1 of the fourth embodiment, and the detailed description is omitted.

Since the spindle motor 70 according to the eighth embodiment is configured as described above, the spindle motor 70 according to the seventh embodiment can achieve the same effects as the fluid bearing device 1 according to the fourth embodiment. In comparison, its manufacture and assembly are facilitated.
In addition, instead of the hydrodynamic bearing device 1 of the fourth embodiment, the hydrodynamic bearing device 1 of the fifth and sixth embodiments or a modified example thereof can be applied to the spindle motor 70 of the eighth embodiment.

FIG. 9 is a longitudinal sectional view of a recording disk drive apparatus according to the ninth embodiment (Embodiment 9) of the present invention.
As apparent from FIG. 9, the recording disk drive device 8 of the ninth embodiment.
0 includes the spindle motor 70 of the seventh embodiment. The main body portion of the spindle motor 70 is provided slightly closer to the left end than the center in FIG. 9 at the bottom of the base (corresponding to a part of the casing) 71 and is covered with a cover member 81 from above. The cover member 81 seals the inside of the base 71 and forms the inside in a clean space with extremely little dust. The cover member 81 and the base 71 form a casing of the recording disk drive device 80.

The recording disk drive device 80 includes the spindle motor 70 and the spindle motor 70.
A base 71, a cover member 81, a magnetic disk 82, a clamp member 83 of the magnetic disk 82, a recording head 84 for writing and / or reading information on the magnetic disk 82, The arm 85 supports the recording head 84, and the voice coil motor 86 moves the recording head 84 and the arm 85 to required positions. Two magnetic disks 82 are mounted on the rotor hub 72, but the number of magnetic disks 82 is not limited to this. The magnetic disk 82 rotates with the rotation of the rotor hub 72.

The recording head 84 is attached to the tip of the head stack assembly fixed to an arm 85 that is pivotably supported at an appropriate position on the bottom of the base 71 so as to form a pair. The pair of upper and lower recording heads 84 are arranged so as to sandwich one magnetic disk 82, and write and / or read information on both surfaces of the magnetic disk 82. Therefore, a pair of recording heads 84 is provided for each magnetic disk 82. In this magnetic disk drive device 80, since there are two magnetic disks 82, two pairs of recording heads 84 are provided as shown in the figure, but the number of magnetic disks 82 is limited to this. It is not done.

The magnetic disk drive device 80 according to the ninth embodiment is configured as described above.
Example 7 obtained by applying any one of the hydrodynamic bearing device 1 of No. 3 or its modification example
Since the spindle motor 70 is applied, it has a simple structure and has the necessary bearing rigidity, is less likely to vibrate, reduces the axial loss torque as much as possible, and reduces power consumption. It is possible to provide a high spindle motor and a recording disk driving device including the spindle motor.

The magnetic disk drive device 80 of the ninth embodiment also includes a spindle motor 70 of the seventh embodiment.
Instead of this, it is possible to apply the spindle motor 70 of the eighth embodiment, and the magnetic disk drive device 80 configured in this way also has substantially the same effect as the magnetic disk drive device 80 of the ninth embodiment. Can play.

As mentioned above, although the 1st-9th Example (Examples 1-9) of the invention of this application was described, in the range which does not deviate from the summary, the invention of this application is not limited to the above Example. Deformation is possible.
For example, in the ninth embodiment, the spindle motor 70 of the seventh or eighth embodiment is
Although applied to the magnetic disk drive 80, it may be a recording disk such as a CD or a DVD instead of the magnetic disk, and the spindle motor 70 is used as a recording disk drive for driving these recording disks. It may be applied.

1 is a longitudinal sectional view of a hydrodynamic bearing device showing a first embodiment (embodiment 1) of the invention of the present application. It is a longitudinal cross-sectional view of the hydrodynamic bearing apparatus which shows 2nd Example (Example 2) of invention of this application. It is a longitudinal cross-sectional view of the hydrodynamic bearing apparatus which shows the 3rd Example (Example 3) of invention of this application. It is a longitudinal cross-sectional view of the hydrodynamic bearing apparatus which shows 4th Example (Example 4) of invention of this application. It is a longitudinal cross-sectional view of the hydrodynamic bearing apparatus which shows 5th Example (Example 5) of invention of this application. It is a longitudinal cross-sectional view of the hydrodynamic bearing apparatus which shows the 6th Example (Example 6) of invention of this application. It is a longitudinal cross-sectional view of the spindle motor which shows 7th Example (Example 7) of invention of this application. It is a longitudinal cross-sectional view of the spindle motor which shows the 8th Example (Example 8) of invention of this application. It is a longitudinal cross-sectional view of the recording disk drive device which shows the 9th Example (Example 9) of the invention of this application. It is a longitudinal cross-sectional view of the shaft rotation type spindle motor in which the conventional hydrodynamic bearing device was used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fluid dynamic bearing apparatus, 10 ... Bearing case, 11 ... (Stepped) cylindrical hole, 11a ... Large diameter part, 1
1b ... small diameter portion, 11c ... step portion, 11d ... expanded diameter portion, 11e ... step portion, 11f ... taper portion, 12
An annular groove, 13 a seal portion, 14 an annular groove, 20 an end plate, 21 an inner surface of the end plate, 30 a shaft (stepped), 31 a a large diameter portion, 31 b a small diameter portion, 31 c a step Part,
31f ... taper part, 32 ... annular groove, 33 ... shaft lower end surface, 40 ... annular ring, 51 ... first
, 52 ... second dynamic pressure groove, 53 ... third dynamic pressure groove, 54 ... fourth dynamic pressure groove, 60 ... thrust ring, 61 ... upper surface, 62 ... lower surface, 70 ... spindle motor, 71 ... Base, 72 ...
Rotor hub, 72a ... cylindrical wall, 72b ... expanded diameter part, 73 ... stator, 74 ... permanent magnet, 7
5 ... flexible wiring board, 76 ... cylindrical wall, 77 ... suction plate, 78 ... ring for retaining,
DESCRIPTION OF SYMBOLS 80 ... Recording disk drive device 81 ... Cover member 82 ... Magnetic disk 83 ... Clamp member 84 ... Recording head 85 ... Arm 86 ... Voice coil motor

Claims (11)

A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and a bearing container formed by the bearing case and the end plate are at least partially inserted. A hydrodynamic bearing device comprising: a shaft body supported by
The cylindrical hole of the bearing case is a stepped cylindrical hole having a large diameter part on the other end side of the bearing case and a small diameter part on the one end part side of the bearing case,
The shaft body is a stepped shaft body having a large diameter portion and a small diameter portion facing the large diameter portion and the small diameter portion of the stepped cylindrical hole,
Either the large-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large-diameter portion of the stepped shaft body has a first
Dynamic pressure grooves are formed,
Either of the small diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small diameter portion of the stepped shaft body includes a second
Dynamic pressure grooves are formed,
A third dynamic pressure groove is formed on either the inner surface of the end plate and the end surface on the one end portion side of the stepped shaft body,
A minute gap between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove is filled with lubricating oil for generating dynamic pressure. Fluid bearing device. A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and a bearing container formed by the bearing case and the end plate are at least partially inserted. A hydrodynamic bearing device comprising: a shaft body supported by
The cylindrical hole of the bearing case is a stepped cylindrical hole having a large diameter part on the other end side of the bearing case and a small diameter part on the one end part side of the bearing case,
The shaft body is a stepped shaft body having a large diameter portion and a small diameter portion facing the large diameter portion and the small diameter portion of the stepped cylindrical hole,
Either the large-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large-diameter portion of the stepped shaft body has a first
Dynamic pressure grooves are formed,
Either of the small diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small diameter portion of the stepped shaft body includes a second
Dynamic pressure grooves are formed,
A third dynamic pressure groove is formed on either the step portion of the stepped cylindrical hole or the surface of the step portion of the stepped shaft body,
A minute gap between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove is filled with lubricating oil for generating dynamic pressure. Fluid bearing device. A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and a bearing container formed by the bearing case and the end plate are at least partially inserted. A hydrodynamic bearing device comprising: a shaft body supported by
The cylindrical hole of the bearing case has a large diameter portion on the other end side of the bearing case, a small diameter portion on the one end portion side of the bearing case, and a tapered portion connecting the large diameter portion and the small diameter portion. A stepped cylindrical hole,
The shaft body is a stepped shaft body having a large diameter portion, a small diameter portion, and a taper portion that respectively oppose the large diameter portion, the small diameter portion, and the taper portion of the stepped cylindrical hole,
Either the large-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large-diameter portion of the stepped shaft body has a first
Dynamic pressure grooves are formed,
Either of the small diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small diameter portion of the stepped shaft body includes a second
Dynamic pressure grooves are formed,
Either of the tapered portion of the stepped cylindrical hole and the outer peripheral surface of the tapered portion of the stepped shaft body,
A third dynamic pressure groove is formed;
A minute gap between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, and the third dynamic pressure groove is filled with lubricating oil for generating dynamic pressure. Fluid bearing device. An annular ring for preventing the shaft body from coming off is inserted so as to straddle the annular groove formed in the cylindrical hole of the bearing case and the annular groove formed in the outer peripheral surface of the shaft body. The hydrodynamic bearing device according to any one of claims 1 to 3, wherein the hydrodynamic bearing device is provided. A hydrodynamic bearing device in which a rotor hub forming a rotating element is fitted to an upper end portion of the shaft body,
An annular groove is formed on the outer peripheral surface of the upper end of the bearing case,
An annular ring having a width smaller than the width of the annular groove is fixed to the surface of the rotor hub facing the annular groove, and is provided so as to be located in the annular groove, The hydrodynamic bearing device according to any one of claims 1 to 3, wherein the shaft body is prevented from coming off. A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and a bearing container formed by the bearing case and the end plate are at least partially inserted. A hydrodynamic bearing device comprising: a shaft body supported by the shaft; and a thrust ring fitted to one end of the shaft body.
The cylindrical hole of the bearing case has a large diameter portion on the other end side of the bearing case, a small diameter portion on the one end portion side of the bearing case, and one end portion of the bearing case for receiving the thrust ring. A stepped cylindrical hole having an enlarged diameter portion,
The shaft body is a stepped shaft body having a large diameter portion and a small diameter portion facing the large diameter portion and the small diameter portion of the stepped cylindrical hole,
Either the large-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large-diameter portion of the stepped shaft body has a first
Dynamic pressure grooves are formed,
Either of the small diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small diameter portion of the stepped shaft body includes a second
Dynamic pressure grooves are formed,
A third dynamic pressure groove is formed on either the inner surface of the end plate and the lower surface of the thrust ring,
A fourth dynamic pressure groove is formed on either the stepped portion connected to the enlarged diameter portion of the stepped cylindrical hole and the upper surface of the thrust ring facing the stepped portion,
Lubrication for generating dynamic pressure is provided in minute gaps between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, the third dynamic pressure groove, and the fourth dynamic pressure groove, respectively. A hydrodynamic bearing device filled with oil. A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and a bearing container formed by the bearing case and the end plate are at least partially inserted. A hydrodynamic bearing device comprising: a shaft body supported by the shaft; and a thrust ring fitted to one end of the shaft body.
The cylindrical hole of the bearing case has a large diameter portion on the other end side of the bearing case, a small diameter portion on the one end portion side of the bearing case, and one end portion of the bearing case for receiving the thrust ring. A stepped cylindrical hole having an enlarged diameter portion,
The shaft body is a stepped shaft body having a large diameter portion and a small diameter portion facing the large diameter portion and the small diameter portion of the stepped cylindrical hole,
Either the large-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large-diameter portion of the stepped shaft body has a first
Dynamic pressure grooves are formed,
Either of the small diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small diameter portion of the stepped shaft body includes a second
Dynamic pressure grooves are formed,
A third dynamic pressure groove is formed on either the step portion of the stepped cylindrical hole or the surface of the step portion of the stepped shaft body,
A fourth dynamic pressure groove is formed on either the stepped portion connected to the enlarged diameter portion of the stepped cylindrical hole and the upper surface of the thrust ring facing the stepped portion,
Lubrication for generating dynamic pressure is provided in minute gaps between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, the third dynamic pressure groove, and the fourth dynamic pressure groove, respectively. A hydrodynamic bearing device filled with oil. A cylindrical bearing case having a cylindrical hole in the center, an end plate that closes one end of the bearing case, and a bearing container formed by the bearing case and the end plate are at least partially inserted. A hydrodynamic bearing device comprising: a shaft body supported by the shaft; and a thrust ring fitted to one end of the shaft body.
The cylindrical hole of the bearing case includes a large diameter portion on the other end side of the bearing case, a small diameter portion on the one end portion side of the bearing case, a tapered portion connecting the large diameter portion and the small diameter portion, A diameter-enlarged portion for receiving the thrust ring at one end of the bearing case, and a stepped cylindrical hole having
The shaft body is a stepped shaft body having a large diameter portion, a small diameter portion, and a taper portion that respectively oppose the large diameter portion, the small diameter portion, and the taper portion of the stepped cylindrical hole,
Either the large-diameter portion of the stepped cylindrical hole or the outer peripheral surface of the large-diameter portion of the stepped shaft body has a first
Dynamic pressure grooves are formed,
Either of the small diameter portion of the stepped cylindrical hole and the outer peripheral surface of the small diameter portion of the stepped shaft body includes a second
Dynamic pressure grooves are formed,
Either of the tapered portion of the stepped cylindrical hole and the outer peripheral surface of the tapered portion of the stepped shaft body,
A third dynamic pressure groove is formed;
A fourth dynamic pressure groove is formed on either the stepped portion connected to the enlarged diameter portion of the stepped cylindrical hole and the upper surface of the thrust ring facing the stepped portion,
Lubrication for generating dynamic pressure is provided in minute gaps between the opposing surfaces facing the first dynamic pressure groove, the second dynamic pressure groove, the third dynamic pressure groove, and the fourth dynamic pressure groove, respectively. A hydrodynamic bearing device filled with oil. A spindle motor comprising the hydrodynamic bearing device according to any one of claims 1 to 5,
A stator,
A rotor hub that forms a rotating element that is fitted to the upper end of the shaft body, and a rotor magnet that is fitted to the rotor hub and generates a rotating magnetic field in cooperation with the stator, and is rotatable with respect to the housing And a rotor provided in
The hydrodynamic bearing device supports the rotation of the rotor;
The rotor is attracted by a magnetic force in a direction opposite to a direction in which a dynamic pressure generated in a dynamic pressure groove for generating a dynamic pressure that receives a load in an axial direction in the hydrodynamic bearing device is applied. The spindle motor is characterized in that the load is supported by balancing the magnetic force with the magnetic force. A spindle motor comprising the hydrodynamic bearing device according to any one of claims 6 to 8,
A stator,
A rotor hub that forms a rotating element that is fitted to the upper end of the shaft body, and a rotor magnet that is fitted to the rotor hub and generates a rotating magnetic field in cooperation with the stator, and is rotatable with respect to the housing And a rotor provided in
The spindle motor characterized in that the hydrodynamic bearing device supports the rotation of the rotor. A recording disk drive device comprising the spindle motor according to claim 9 or 10,
A recording head for writing and / or reading information on a recording disk;
A recording disk drive apparatus, wherein the spindle motor rotates the recording disk.

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