KR20170044581A - A fluid hydrodynamic bearing - Google Patents

Abstract

Provided is a fluid dynamic pressure bearing which has a high rotation precision and load capacity and a low torque. The fluid dynamic pressure bearing (101) of the present invention comprises: a shaft member (104); an outer ring unit (102) which is rotatable towards the shaft member (104); and a radial clearance (103) in between the shaft member (104) and the outer ring unit (102). An outer circumferential surface (107) of the shaft member (104) comprises: a first surface area (108); a second surface area (109); and a first fluid dynamic pressure maintaining area (110). When the outer ring unit (102) passes through the first fluid dynamic pressure maintaining area (110) from the first surface area (108) towards the shaft member (104), and rotates to head for the second surface area (109), in a first weight load area, which is placed on the first fluid dynamic pressure maintaining area (110) of the radial clearance (103), a dynamic pressure groove (111) is formed on the first surface area (108) to generate a dynamic pressure by a fluid which flows from the first surface area (108) to the first fluid dynamic pressure maintaining area (110).

Description

{A FLUID HYDRODYNAMIC BEARING}

The present invention relates to a fluid dynamic pressure bearing having high rotation accuracy and load capacity and excellent low torque characteristics.

There is known a cam follower of a rolling bearing having a cylindrical outer ring, a stud inserted in the outer ring in the axial direction, and a roller rotated between the outer ring and the stud in accordance with the rotation of the outer ring. A cam follower provided with a retainer for retaining the cam follower, and a full compliment roller type cam follower which does not use the retainer. Such a cam follower of the rolling bearing is used for a cam mechanism, for example, a roller gear cam mechanism, a barrel cam mechanism, etc. However, since the outer diameter of the outer ring is restricted by the positional relationship with the cam, . Therefore, as a substitute for the cam follower of the rolling bearing, by using the cam follower of the sliding bearing, the stud diameter can be made thick or the thickness of the outer ring can be made thick.

Patent Document 1 discloses a cam follower including a shaft member that is cantilevered at one end and a slide bearing that is mounted on the outer circumference of the other end of the shaft member. The sliding bearing is constituted by a cylindrical mother body made of an Fe-based sintered metal material having an Fe content of 90 wt% or more and a sliding layer formed on both end faces from the inner peripheral face of the mother body. The sliding layer is made of, for example, And a sliding material composition in which a base material is blended with a lubricant such as silicone oil and spherical porous silica impregnated with the lubricant.

Patent Document 2 discloses a bearing device comprising a bearing sleeve having an inner circumference and a dynamic pressure groove region in which a plurality of dynamic pressure grooves are arranged in the circumferential direction and a shaft member inserted into the inner periphery of the bearing sleeve, Contact bearing in the radial direction in the forward and reverse rotation directions by the dynamic pressure action of the fluid generated in the radial bearing gap between the dynamic pressure groove regions of the inner circumference of the sleeve. The bearing sleeve is made of sintered metal and has a first pressure-for-purpose dynamic pressure groove region on one side in the axial direction and a second pressure-side groove region for the second reverse side on the other side in the axial direction, The dynamic pressure groove region dedicated for the first reverse rotation has the dynamic pressure groove inclined with respect to the axial direction and the dynamic pressure groove inclined in the direction opposite to the axial direction at different positions in the axial direction.

Japanese Patent Application Laid-Open No. 2005-24094 Japanese Patent Application Laid-Open No. 2005-351374

Since the base of the sliding bearing is formed of the Fe-based sintered metal material, the cam follower according to Patent Document 1 can obtain high dimensional precision and rotational accuracy, and the sliding layer is formed using the polyethylene resin as the base material , And low friction properties. However, since the coefficient of friction between the shaft member and the sliding bearing is 0.08, which is greater than the coefficient of friction between the outer ring and the stud of the cam follower of the rolling bearing having the roller to be rotated, There is a problem that a large torque is required to rotate and the load capacity is small.

The dynamic pressure bearing according to Patent Document 2 has a dynamic pressure groove which is inclined in the axial direction with respect to the axial direction and a dynamic pressure groove which is inclined in the opposite direction to the axial direction in the inner circumference of the bearing sleeve at different positions in the axial direction, , Causing dynamic pressure action of the fluid on the radial bearing clearance between the shaft member and the bearing sleeve. However, since the fluid flows in the reverse direction in the respective regions from the point of having the dynamic pressure groove region for exclusive use in the axial direction on one side in the axial direction and having the dynamic pressure groove region exclusively for reverse rotation on the other side in the axial direction, And there is a problem that friction between the shaft member and the bearing sleeve can not be made sufficiently small.

Accordingly, an object of the present invention is to provide a fluid dynamic pressure bearing capable of reducing torque, having high rotational accuracy, capable of being used without any trouble even with a large load, and capable of reducing torque.

According to the present invention, the above object is achieved by a fluid dynamic pressure bearing having a shaft member and an outer ring portion rotatable along the outer circumferential surface of the shaft member, wherein a radial clearance is provided between an outer circumferential surface of the shaft member and an inner circumferential surface of the outer ring portion, Wherein the outer peripheral surface includes a first fluid dynamic pressure holding region disposed between the first surface region, the second surface region, and the first surface region and the second surface region, and the outer ring portion includes a first fluid dynamic pressure holding region In the first load bearing region located on the first fluid dynamic pressure holding region of the radial clearance when the first fluid dynamic pressure holding region is rotated from the surface region through the first fluid dynamic pressure holding region toward the second surface region, A dynamic pressure groove is formed in the first surface area so as to generate a dynamic pressure by the fluid flowing from the first surface area to the first fluid dynamic pressure holding area Fluid hydrodynamic bearings.

Another object of the above-mentioned object is also achieved in that when the outer ring portion rotates from the second surface area along the outer peripheral surface of the shaft member to the first surface area through the first fluid dynamic pressure holding area, In which a dynamic pressure groove is formed in a second surface area so as to be able to generate dynamic pressure by fluid flowing from the second surface area to the first fluid dynamic pressure holding area in accordance with rotation of the outer race part .

Another aspect of the above object is to provide a fluid dynamic pressure generating device in which a dynamic pressure groove of a first surface area is formed by a plurality of grooves having a substantially V shape and a vertex portion of a substantially V shape is formed so as to face a second surface area, Is accomplished by a bearing.

Another object of the present invention is to provide a fluid dynamic pressure generating device in which a dynamic pressure groove of a second surface area is formed by a plurality of grooves having a substantially V shape and a vertex portion of a substantially V shape is formed so as to face a first surface area, Is accomplished by a bearing.

Another object of the present invention is achieved by a fluid dynamic pressure bearing in which a plurality of dimples are formed on an outer peripheral surface of a shaft member in a first fluid dynamic pressure holding region.

Another object of the present invention is achieved by a fluid dynamic pressure bearing in which an outer circumferential surface of a shaft member is provided with an arcuate groove along its circumferential direction.

Another object of the present invention is achieved by a fluid dynamic pressure bearing in which an outer race portion is provided with a passage hole extending from an outer circumferential surface to an inner circumferential surface thereof.

Another object of the above-mentioned object is also achieved in that the outer peripheral surface of the shaft member further includes a third surface region, a fourth surface region, and a second fluid dynamic pressure holding region disposed between the third surface region and the fourth surface region And when the outer ring portion rotates from the first surface area along the outer peripheral surface of the shaft member to the second surface area through the first fluid dynamic pressure holding area and rotates on the second fluid dynamic pressure holding area in the radial clearance A dynamic pressure groove is formed in the third surface area so as to generate dynamic pressure by the fluid flowing from the third surface area to the second fluid dynamic pressure holding area in accordance with the rotation of the outer ring part in the second load load area located, When the outer ring portion rotates from the second surface area along the outer peripheral surface of the shaft member to the first surface area through the first fluid dynamic pressure holding area, In the fourth to generate a braking pressure by the fluid flowing into second fluid dynamic pressure of the region from the surface region, and the fourth is achieved by a fluid dynamic pressure bearing with dynamic pressure grooves are formed in the surface area in accordance with the paddle rotating portion.

Another object of the present invention is to provide a hydrodynamic bearing having an outer peripheral surface of a shaft member including a third surface region and a fourth surface region on opposite sides of an axis of a shaft member of a first surface region and a second surface region, Lt; / RTI >

Another object of the present invention is achieved by a fluid dynamic pressure bearing in which the outer diameter of the outer peripheral surface of the shaft member is larger than the outer diameter of the insertion portion of the shaft member.

Another object of the above-mentioned object is achieved by a fluid dynamic pressure bearing which is a cam follower or a roller follower.

Another object of the present invention is to provide a cam mechanism including a rotatable cam having a cam rib in the form of a screw and a rotatable member rotatable in accordance with rotation of the cam, wherein the rotatable member includes a plurality of the hydrodynamic pressure bearings And the cam rib is brought into contact with at least one of the plurality of fluid dynamic pressure bearings so that the rotating member is caused to rotate.

Another object of the present invention is to provide a fluid dynamic pressure bearing structure in which each first fluid dynamic pressure holding region of a plurality of fluid dynamic pressure bearings faces a cam rib when the cam rib contacts each of the plurality of fluid dynamic pressure bearings, And each of the shaft members is fixed to the rotary member.

Another object of the present invention is to provide a cam mechanism having a rotatable planar cam and a member operable in accordance with the rotation of the planar cam, wherein the member has the hydrodynamic bearing at the tip thereof, And a cam mechanism in which the member is operated by being brought into contact with the hydrodynamic bearing.

Another object of the above-mentioned object is also achieved in that when the planar cam contacts the hydrodynamic pressure bearing, the first fluid dynamic pressure holding region of the hydrodynamic bearing faces the plane cam so that the shaft member of the hydrodynamic pressure bearing is fixed to the member Is accomplished by a mechanism.

As described above, by forming the dynamic pressure grooves in the first surface area of the outer peripheral surface of the shaft member, it is possible to reduce the friction between the shaft member and the outer ring portion by generating dynamic pressure by the fluid in the first load- Can be reduced, a high rotation accuracy can be achieved, and a bearing which can be used without any hindrance even with a large load can be realized. Further, by forming the dynamic pressure grooves in the second surface area of the outer peripheral surface of the shaft member, dynamic pressure is generated by the fluid in the first load-applied region of the radial clearance even when the outer ring portion is rotated forward or backward relative to the shaft member And the friction between the shaft member and the outer ring portion can be reduced. Further, by forming the dynamic pressure grooves in a substantially V-shape, it is possible to generate dynamic pressure more efficiently. Further, by forming dimples and arc grooves, it is possible to generate dynamic pressure more efficiently.

Further, by using the hydrodynamic pressure bearing of the present invention in a cam mechanism, it is possible to realize a cam mechanism that has high rotation accuracy and load capacity and is suitable for longevity improvement and that the hydrodynamic bearing of the present invention has no rollers, .

Further objects, features and advantages of the present invention will become apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional side view of a hydrodynamic bearing of the present invention.
2 is a schematic view of the first embodiment seen from one side of the shaft member.
Fig. 3 is a schematic view of the second embodiment seen from one side of the shaft member; Fig.
4 is a schematic view of the third embodiment seen from one side of the shaft member.
Fig. 5 is a schematic view of the fourth embodiment seen from one side of the shaft member. Fig.
6 is a schematic view of the fifth embodiment seen from one side of the shaft member.
7 is a schematic view of the sixth embodiment seen from one side of the shaft member.
8 is a schematic view of the seventh embodiment seen from one side of the shaft member.
9 is a schematic view of an eighth embodiment seen from one side of the shaft member.
10 is a schematic view of the ninth embodiment seen from one side of the shaft member.
11 is a schematic view of the tenth embodiment seen from one side of the shaft member.
12 is a schematic view of the eleventh embodiment seen from one side of the shaft member.
13 is a schematic view of the first embodiment seen from the opposite side of the shaft member.
14 is a schematic view of the second embodiment seen from the opposite side of the shaft member.
Fig. 15 is a sectional view seen from the front of the outer ring portion. Fig.
16 is a partial perspective view seen from the side of the outer ring portion.
17 is a front view of the cam mechanism using the fluid dynamic pressure bearing of the present invention.
Fig. 18 is a schematic cross-sectional view of the hydrodynamic bearing of the present invention as viewed from the bottom in contact with the cam surface. Fig.
19 is a front view of a separate cam mechanism using the fluid dynamic pressure bearing of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

1 to 19, an embodiment of the fluid dynamic pressure bearing of the present invention and an embodiment of the cam mechanism using the fluid dynamic pressure bearing of the present invention will be described.

1 shows a cross-sectional view of a fluid dynamic pressure bearing 101. As shown in Fig. The fluid dynamic pressure bearing 101 includes a shaft member 104 and an outer ring portion 102 rotatable along the outer circumferential surface 107 of the shaft member 104. The outer peripheral surface 107 of the shaft member 104, A radial clearance 103 is provided between the inner circumferential surface 120 of the portion 102. 1, the hydrodynamic pressure bearing 101 further includes an insertion portion 105 for fitting the hydrodynamic pressure bearing 101 to a rotary member such as a turret of a cam mechanism, an insertion portion 105 And a fixing member receiving hole 106 for receiving a fixing member such as a bolt for fixing the shaft member 104 to the turret interposed therebetween. The insertion portion 105 and the fixing member receiving hole 106 are provided You do not have to.

2 shows a schematic view of the first embodiment viewed from the side with respect to the shaft member 104 of the fluid dynamic pressure bearing 101 of Fig. The outer circumferential surface 107 of the shaft member 104 has a first surface area which is the first regular-motion dedicated dynamic pressure generating area 108, a second surface area which is the first reverse-dedicated dynamic pressure generating area 109, And a first fluid dynamic pressure holding region (110) disposed between the region (108) and the first reverse rotation dedicated pressure generating region (109). In addition, the dotted lines shown in Figs. 2 to 14 are for the sake of convenience in explaining each area. The outer ring portion 102 passes the first fluid dynamic pressure holding region 110 from the first regular-motion-dedicated dynamic pressure generating region 108 along the outer peripheral surface 107 of the shaft member 104, 18) located on the first fluid dynamic pressure holding region 110 among the radial clearance 103 in the radial gap 103 Dedicated dynamic pressure generating region 108 so as to generate dynamic pressure by a fluid such as oil flowing from the first forbidden dynamic pressure generating region 108 to the first fluid dynamic pressure holding region 110 in accordance with the rotation of the first portion 102, The region 108 is formed with a dynamic pressure groove 111 which is recessed with respect to the outer peripheral surface 107. When the dynamic pressure grooves 111 are formed in the first straight-run dedicated dynamic pressure generating area 108 in this manner, fluid such as oil flows along the first straight-run dedicated dynamic pressure generating area 108 before the outer ring part 102 turns. To the first fluid dynamic pressure holding region 110 along the dynamic pressure groove 111 of the first fluid dynamic pressure holding region 110 and the concentrated fluid is blocked at the tip end thereof, A film of a fluid having a high pressure is formed in the first load-bearing region located on the first fluid dynamic pressure holding region 110, and dynamic pressure is generated by the fluid. Due to the dynamic pressure of the fluid, the outer ring portion 102 does not contact the shaft member 104 in the first fluid dynamic pressure holding region 110, and can rotate at low friction and low torque.

The outer ring portion 102 also passes through the first reverse dynamic pressure generating region 109 along the outer peripheral surface 107 of the shaft member 104 and passes through the first fluid dynamic pressure holding region 110, 18) located on the first fluid dynamic pressure holding region 110 out of the radial gap 103 when the first fluid dynamic pressure holding region 110 is rotated so as to face the region 108 (reverse rotation) So that the dynamic pressure can be generated by the fluid such as oil flowing from the first reverse dynamic pressure generating region 109 to the first fluid dynamic pressure holding region 110 in accordance with the rotation of the outer ring portion 102, The dynamic pressure generating region 109 may be provided with a dynamic pressure groove 111 which is recessed with respect to the outer peripheral surface 107. [ If the dynamic pressure grooves 111 are formed in the first reverse rotation dedicated pressure generating area 109 as described above, fluid such as oil flows in the first reverse rotation dedicated dynamic pressure generating area 109 Flows toward the first fluid dynamic pressure holding region 110 along the dynamic pressure groove 111 of the first fluid dynamic pressure holding region 110 so that the concentrated fluid is clogged at the tip portion thereof, A film of a fluid having a high pressure is formed in the first load bearing region 110 located on the first fluid dynamic pressure holding region 110 of the gap 103 and dynamic pressure is generated by the fluid. Due to the dynamic pressure of the fluid, the outer ring portion 102 does not contact the shaft member 104 in the first fluid dynamic pressure holding region 110, and can rotate at low friction and low torque.

The dynamic pressure grooves 111 in the first surface area, which is the first for-ahead dedicated pressure generating area 108, may be formed by grooves having a plurality of substantially V-shaped grooves, and the apex of the substantially V- Or may be formed so as to face the generation region 109. The dynamic pressure grooves 111 in the second surface area, which is the first reverse-rotation dedicated pressure generating area 109, may be formed by grooves having a plurality of substantially V-shaped grooves. The apex of the substantially V- Or may be formed so as to face the dedicated dynamic pressure generating area 108. By making the dynamic pressure groove 111 a groove having a substantially V shape, the fluid flows so as to be concentrated at the apex portion 112, which is the tip portion of the substantially V shape, and the concentrated fluid is blocked at the apex portion 112 thereof A film of a fluid having a high pressure is formed in the first load bearing region located on the first fluid dynamic pressure holding region 110 of the radial gap 103 and a dynamic pressure is generated by the fluid.

The apex portion 112 of the substantially V-shape as the dynamic pressure grooves 111 of the first regular-motion-dedicated dynamic pressure generating region 108 and the apex portion 112 of the dynamic pressure grooves 111 of the first reverse- The V-shaped vertex portions 112 are formed so as to face each other so that the radial clearance between the radial clearance 103 and the first fluid dynamic pressure holding region 110 can be maintained even when the outer ring portion 102 rotates in the forward direction, It is possible to form a film of a fluid having a high pressure in the first load-applied region located in the first load-bearing region.

One or more arcuate grooves 114 may be formed in the outer circumferential surface 107 of the shaft member 104 along the circumferential direction of the outer circumferential surface 107 as shown in Fig. It is also possible to form the arc groove 114 so as to connect the apex portion 112 of the substantially V shape which is the tip portion of the dynamic pressure groove 111. With this configuration, In the dynamic pressure grooves 111 of the one reverse-pressure dedicated pressure generating area 109, grooves of a herringbone shape facing each other are formed. By forming the arcuate grooves 114 on the outer circumferential surface 107 of the shaft member 104, the fluid is concentrated more efficiently and a film of fluid having a high pressure in the first load-applied region is formed, Occurs.

4, the first fluid dynamic pressure holding region (the first fluid dynamic pressure holding region 108) between the first regular-motion dedicated dynamic pressure generating region 108 and the first reverse-facing dedicated dynamic pressure generating region 109 is formed in the outer peripheral surface 107 of the shaft member 104 110, dimples 113 of a plurality of concave shapes may be formed. The dimple 113 preferably has an outer diameter of 100 mu m or less, preferably 50 mu m or less. A plurality of dimples 113 are formed in the first fluid dynamic pressure holding region 110 so that when the outer ring portion 102 is rotating forward or backward relative to the shaft member 104, , Acts as a reservoir for the fluid flowing from the first forboth dynamic pressure generating region 108 or the first reverse dubbing dynamic pressure generating region 109 toward the first fluid dynamic pressure holding region 110, Can be improved. Therefore, a film of a fluid having a high pressure is additionally formed in the first load-bearing region located on the first fluid dynamic pressure holding region 110 of the radial gap 103, thereby generating dynamic pressure by the fluid . Due to the dynamic pressure of the fluid, the outer ring portion 102 does not contact the shaft member 104 in the first fluid dynamic pressure holding region 110, and can rotate at low friction and low torque. 4, the dimples 113 may be formed in the first straight-running dedicated dynamic pressure generating region 108 and the first reverse-dedicated dynamic pressure generating region 109, and the dimples 113 may be formed on the outer peripheral surface of the shaft member 104 Or may be formed on the entire surface of the substrate 107.

Figs. 5 to 10 show the fourth to ninth embodiments. Fig. 5 shows an embodiment in which the dimple 113 is formed in the embodiment of Fig. 3, Fig. 6 shows an embodiment in which the number of the dynamic pressure grooves 111 formed in the embodiment of Fig. 3, 6 is an embodiment in which the dimple 113 is formed in the embodiment of FIG. 6, FIG. 8 is an embodiment in which the circular arc groove 114 of the embodiment of FIG. 6 is formed in an annular shape, Is an embodiment in which dimples 113 are formed in the embodiment of Fig. 8, and Fig. 10 is an embodiment showing other shapes of the dynamic pressure grooves. By combining the dynamic pressure grooves, the circular grooves and the dimples of all shapes in this manner, dynamic pressure can be generated, and various shapes can be selected according to the environment in which the fluid dynamic pressure bearing is used, such as the magnitude of the moment load. The shape of the dynamic pressure groove, the circular groove, and the dimple formed in the outer peripheral portion 107 is not limited to these examples.

2 to 10, the dynamic pressure grooves 111 of the first straight-run dedicated dynamic pressure generating region 108 and the dynamic pressure grooves 111 of the first reverse-designated exclusive dynamic pressure generating region 109 are formed by the shaft members 104 As shown in Figs. 11 and 12, the first and second reverse-dedicated dynamic pressure generating regions 108 and 109 are formed so as to have a symmetrical shape with respect to the axis 104a of the first reverse- The one fluid dynamic pressure holding region 110 may be included in the outer peripheral surface 107 of the shaft member 104 so as to have an angle a with respect to the axis 104a of the shaft member 104. [ In addition, the dimples 113 may be formed so as to be distributed so as to have a substantially angle? With respect to the axis 104a. The angle alpha is set such that the angle alpha is set at a position where the outer ring portion 102 of the hydrodynamic pressure bearing 101 is most pressed by the fluid dynamic pressure bearing 101 when the fluid dynamic pressure bearing 101 is used in the cam mechanism, It is determined that the dynamic pressure can be generated. By providing the angle? In this manner, the friction between the shaft member 104 and the outer ring portion 102 can be reduced in accordance with the cam mechanism in which the fluid dynamic pressure bearing 101 is used.

As shown in Figs. 13 and 14, the outer peripheral surface 107 of the shaft member 104 is divided into a second regular-motion dedicated dynamic pressure generating region 115 as a third surface region, a second reverse- 116), and a second fluid dynamic pressure holding region 117 disposed between the second regular-motion dedicated dynamic pressure generating region 115 and the second reverse-dedicated dynamic pressure generating region 116. The outer ring portion 102 passes the second fluid dynamic pressure holding region 117 from the second normal-motion-dedicated dynamic pressure generating region 115 along the outer peripheral surface 107 of the shaft member 104, 116), that is, along the outer circumferential surface 107 of the shaft member 104 from the first regular-motion dedicated dynamic pressure generating region 108 through the first fluid dynamic pressure holding region 110, 18) located on the second fluid dynamic pressure holding region 117 of the radial gap 103 when the rotor is rotated so as to face the dedicated dynamic pressure generating region 109 So as to generate dynamic pressure by a fluid such as oil flowing from the second forbidden dynamic pressure generating area 115 to the second fluid dynamic pressure holding area 117 in accordance with the rotation of the outer ring part 102, 2 dynamic pressure-generating dynamic pressure generating area 115, 111, or it may have been formed. The outer ring portion 102 is moved from the second reverse-rotation dedicated pressure generating region 116 along the outer peripheral surface 107 of the shaft member 104 to the second fluid dynamic pressure holding region 117, The first reverse dynamic pressure generating region 109 is passed along the outer peripheral surface 107 of the shaft member 104 through the first fluid dynamic pressure holding region 110 (Reverse rotation) in the radial gap 103 in the second load bearing region (second bearing portion) 117 located on the second fluid dynamic pressure holding region 117 It is possible to generate dynamic pressure by a fluid such as oil flowing from the second reverse dynamic pressure generating region 116 to the second fluid dynamic pressure holding region 117 in accordance with the rotation of the outer ring portion 102 The second reverse rotation dedicated dynamic pressure generating region 116 is recessed with respect to the outer peripheral surface 107 Dynamic pressure is even when the groove 111 is formed. As described above, when the dynamic pressure grooves 111 are formed in the second regular-motion-dedicated dynamic pressure generating region 115 and the dynamic pressure grooves 111 are formed in the second reverse-reaction specific dynamic pressure generating region 116, The fluid flows along the second fluid dynamic pressure holding region 117 along the dynamic pressure grooves 111 of the second constant-speed dedicated dynamic pressure generating region 115 or the second non-receding dynamic pressure generating region 116 Of the radial clearance 103 to a position different from the position of the first fluid dynamic pressure holding region 110 by the fluid flowing to be concentrated at the tip end of the dynamic pressure groove 111 toward the center of the radial gap 103, (See FIG. 18) located on the second fluid dynamic pressure holding region 117 disposed on the second fluid dynamic pressure holding region 117, a film of fluid having a high pressure is formed, and a dynamic pressure is generated by the fluid. The outer ring portion 102 does not come into contact with the shaft member 104 even in the second fluid dynamic pressure holding region 117 due to dynamic pressure by the fluid and can rotate at low friction and low torque.

The second forbidden dynamic pressure generating area 115 may be arranged on the opposite side of the first forbidden dynamic pressure generating area 108 to the axis 104a of the shaft member 104 shown in Fig. The second reverse rotation dedicated pressure generating area 116 may be disposed on the opposite side of the first reverse rotation dedicated pressure generating area 109 with respect to the axis 104a of the shaft member 104 shown in FIG.

1, the outer diameter of the outer peripheral surface 107 of the shaft member 104 may be larger than the outer diameter of the insertion portion 105 of the shaft member 104 when the insertion portion 105 is provided . When the fluid dynamic pressure bearing 101 is fitted to the rotary member such as a turret of the cam mechanism by making the outer diameter of the outer peripheral surface 107 larger than the outer diameter of the insertion portion 105, The length of the outer peripheral surface 107 with respect to the direction of the axis 104a of the shaft member 104 is ensured and the outer peripheral surface 107 of the outer ring portion 102 Can smoothly rotate.

The outer ring portion 102 may be provided with the flow path hole 118 communicating from the outer peripheral surface 119 of the outer race portion 102 to the inner peripheral surface 120 as shown in Figs. The radial clearance 103 between the outer circumferential surface 107 of the shaft member 104 and the inner circumferential surface 120 of the outer ring portion 102 from the outer circumferential surface 119 of the outer ring portion 102 The fluid such as oil can flow out and flow smoothly.

The fluid dynamic pressure bearing 101 may be a cam follower or a roller follower.

17 and 18 show a cam mechanism 201 in which a fluid dynamic pressure bearing 101 is used. 17, the cam mechanism 201 includes a cam 202 rotatable about a cam axis 203 having a cam rib 204 in the form of a screw on all or a part of the cam shaft, And a rotary member 207 such as a turret rotatable about the rotary member axis 208 in accordance with the rotation of the rotary member 207. [ 17 shows a deceleration mechanism using a roller gear (globoid) cam as a cam mechanism. However, a deceleration mechanism and an index mechanism using an index mechanism using a roller gear cam, a cylindrical cam, a barrel cam, Or a cam mechanism such as a linear motion mechanism or a rocking mechanism using a flat cam such as a cam. The rotary member 207 is provided with a plurality of fluid dynamic pressure bearings 101 along its outer circumferential direction. A method of mounting the hydrodynamic pressure bearing 101 on the rotary member 207 of the cam mechanism 201 includes rotating the hydrodynamic pressure bearing 101 through the insertion portion 105 of the shaft member 104, A method of inserting a fixing member such as a bolt into the fixing member receiving hole 106 and inserting the fixing member into the fixing member receiving hole 106 to fix the shaft member 104 to the rotating member 207, The insertion portion 105 of the hydrodynamic bearing 101 is inserted into the rotary member 207 and the fixing screw is inserted into the female screw provided at the position where the insertion portion 105 of the rotary member 207 is inserted, (In this case, the insertion portion 105 may be provided with a concave portion having a flat bottom surface, a V-shaped concave portion, or the like), and a method of fixing the fluid dynamic pressure bearing 101 to the rotating member 207 A method in which the insertion portion 105 is press-fitted (tightly fitted) to the rotary member 207 and fixed by a method, a method of fixing the fluid dynamic pressure bearing 101 A method in which the mouth 105 is loosely fitted to the rotary member 207 and a screw loosening fixing adhesive is introduced and fixed to the gap. When the cam 202 rotates, the contact between the first cam surface 205 or the second cam surface 206 of the cam rib 204 and the outer circumferential surface 119 of the outer ring portion 102 of the hydrodynamic pressure bearing 101 causes fluid The outer circumferential surface 119 of the hydrodynamic bearing 101 is pressed and the rotating member 207 rotates so that the outer ring portion 102 of the hydrodynamic pressure bearing 101 is supported by the shaft member 104, So that it is in rolling contact with the cam rib 204.

18 shows the relationship between the outer circumferential surface 119 of the outer ring portion 102 of the fluid dynamic pressure bearing 101 and the first and second cam surfaces 205 and 206 of the cam rib 204 at any timing of the cam mechanism Sectional view showing a contact state. When the cam rib 204 rotates along the direction of the arrow as the cam 202 rotates, the outer race portion 102 of the hydrodynamic pressure bearings 101a and 101c rolling on the cam 202 rotates in the axial direction 104 (clockwise or counterclockwise), and the fluid in the radial gap also rotates as the outer ring portion 102 rotates.

More specifically, the outer ring portion 102 is pressed by the contact between the first cam surface 205 of the cam rib 204 and the outer ring portion 102 of the fluid dynamic pressure bearing 101a, and the center of the outer ring portion 102 And the outer ring portion 102 is supported by the shaft member 104 and is moved from the first forbidden dynamic pressure generating region 108 to the first fluid dynamic pressure Passes through the holding region 110 and rotates clockwise to face the first reverse-rotation dedicated dynamic pressure generating region 109. [ The fluid in the radial gap 103 also flows from the first forbidden dynamic pressure generating region 108 to the first fluid dynamic pressure holding region 110 in accordance with the rotation of the outer ring portion 102. [ Here, it is limited to the portion facing the first cam surface 205 when receiving the load from the outer circumferential surface 107 of the shaft member 104 by the pressure from the first cam surface 205 to the outer ring portion 102 . A film of a fluid with a high pressure is formed in a portion of the outer circumferential surface 107 of the shaft member 104 facing the first cam surface 205 and a dynamic pressure is generated by the fluid so that the shaft member 104 It is necessary to reduce the friction of the outer ring part 102. [ Therefore, the shaft member 104 can be moved to the first fluid dynamic pressure holding region (the first fluid dynamic pressure holding region 108) disposed between the first regular-motion dedicated dynamic pressure generating region 108 included in the outer peripheral surface 107 thereof and the first reverse- The first load bearing region 121 located on the first fluid dynamic pressure holding region 110 among the radial gap 103 can be fixed to the rotating member 207 so as to face the first cam face 205. [ It is possible to generate a dynamic pressure by the fluid and to reduce the friction between the shaft member 104 and the outer ring portion 102. [ The cam 202 rotates in the reverse direction and the outer ring part 102 is supported by the shaft member 104 and then flows from the first reverse rotation dedicated pressure generating area 109 through the first fluid dynamic pressure holding area 110 to the first Clockwise direction so as to face the dynamic pressure dedicated pressure generating area 108, it is possible to generate dynamic pressure by the fluid in the first load-applied load area 121 as well.

When the rotational direction of the outer ring portion 102 of the fluid dynamic pressure bearing 101a is different from the rotational direction of the outer ring portion 102 of the fluid dynamic pressure bearing 101c as shown in Figs. 17 and 18, the fluid dynamic pressure bearing 101b , And may not be in contact with the cam rib 204.

The fluid dynamic pressure bearing 101c is in contact with the second cam surface 206 on the opposite side of the first cam surface 205, that is, the cam surface on the opposite side of the cam surface on which the fluid dynamic pressure bearing 101a contacts. Here, receiving the load on the outer peripheral surface 107 of the shaft member 104 by the pressure from the second cam surface 206 to the outer ring portion 102, as in the hydrodynamic pressure bearing 101a, ) In the area facing the vehicle. Therefore, in order to form a film of a high-pressure fluid and generate a dynamic pressure by the fluid, the outer circumferential surface 107 is formed on the outer circumferential surface 107 of the shaft member 104 facing the second cam surface 206 A second reverse rotation dedicated pressure generation region 116, a second reverse rotation dedicated pressure generation region 115, and a second reverse rotation dedicated pressure generation region 116. The second reverse rotation dedicated pressure generation region 115, the second reverse rotation exclusive pressure generation region 116, Two-fluid dynamic pressure holding region 117 may be further included. The shaft member 104 is connected to the second fluid dynamic pressure holding region (second fluid dynamic pressure holding region) 116 disposed between the second forbidden dynamic pressure generating region 115 included in the outer peripheral face 107 and the second reverse specific pressure generating region 116 117 are fixed to the rotating member 207 so as to face the second cam surface 206, the outer ring portion 102 is supported by the shaft member 104 and the second fluid dynamic pressure The cam 202 also rotates in the opposite direction and the outer ring part 102 rotates in the counterclockwise direction so as to face the second straight-running dedicated dynamic pressure generating area 115 through the holding area 117, Even when it is rotated clockwise from the second regular-motion dedicated dynamic pressure generating region 115 through the second fluid dynamic pressure holding region 117 to the second reverse-dedicated dynamic pressure generating region 116 while being supported by the second fluid dynamic pressure sustaining region 117, In the gap 103, the second load bearing region 122 located on the second fluid dynamic pressure holding region 117 So that dynamic pressure by the fluid can be generated, and friction between the shaft member 104 and the outer ring portion 102 can be reduced.

19 shows a separate cam mechanism 301 in which a fluid dynamic pressure bearing 101 is used. 19, the cam mechanism 301 includes a planar cam 302 rotatable about a planar cam axis 303 and a member 304 operable in accordance with the rotation of the planar cam 302 . The planar cam 302 may be a plate cam, a groove cam, or the like. The member (304) is provided with a hydrodynamic bearing (101) at its tip end. As the planar cam 302 contacts the fluid dynamic pressure bearing 101, the member 304 is operated. For example, as shown in Fig. 19, when the planar cam 302 rotates about the planar cam axis 303, the fluid dynamic pressure bearing (not shown) provided at the end of the member 304 in the end or groove of the planar cam 302 And the member 304 is moved up and down in accordance with the contact by the rotation. When the fluid dynamic pressure bearing 101 is in contact with the shaft member 104 of the fluid dynamic pressure bearing 101 fixed to the front end of the member 304 when the planar cam 302 is in contact with the fluid dynamic pressure bearing 101, The outer ring portion 102 of the outer ring 102 rotates.

In the case where the planar cam 302 and the fluid dynamic pressure bearing 101 are in contact with each other and the outer circumferential surface 107 of the shaft member 104 is pressed by the pressure from the planar cam 302 to the outer ring portion 102 The load receives the end portion of the plane cam 302 and the portion facing the groove. Therefore, when the planar cam 302 is in contact with the hydrodynamic pressure bearing 101, the first straight-running dedicated dynamic pressure generating region 108 included in the outer peripheral surface 107 of the shaft member 104 and the first reverse- The shaft member 104 of the hydrodynamic pressure bearing 101 is inserted into the member 304 so that the first fluid dynamic pressure holding region 110 disposed between the generation region 109 faces the end portion of the planar cam 302, . By fixing the shaft member 104 in this manner, it is possible to generate dynamic pressure by the fluid in the first load-bearing region located on the first fluid dynamic pressure holding region 110 of the radial gap 103, Friction between the shaft member 104 and the outer ring portion 102 can be reduced.

Although the above description has been made with respect to specific embodiments, the present invention is not limited thereto, and it is apparent to those skilled in the art that various changes and modifications can be made within the scope of the principles of the present invention and the appended claims.

101 Fluid dynamic bearing
102 outer ring part
103 Radial clearance
104 shaft member
105 insertion portion
106 Fixing member receiving hole
107 outer peripheral surface of the shaft member
108 First Forward Dedicated Dynamic Pressure Generating Area (First Surface Area)
109 First reverse rotation dedicated pressure generating area (second surface area)
110 first fluid dynamic pressure holding area
111 dynamic pressure home
112 Dynamic pressure groove top part
113 dimple
114 Circular groove
115 Second Forward Dedicated Dynamic Pressure Generating Area (Third Surface Area)
116 Second reversing-only dynamic pressure generating area (fourth surface area)
117 2nd fluid dynamic pressure holding area
118 Euro hole
119 outer circumference of outer ring
120 Inner circumference of outer ring
121 First Load Load Area
122 2nd load load area
201 cam mechanism
202 cam
203 Cam axis
204 cam ribs
205 first cam face
206 Second cam face
207 rotating member
208 Rotation member axis
301 cam mechanism
302 plane cam
303 plane cam axis
304 member

Claims (15)

A hydrodynamic bearing having a shaft member and an outer ring portion rotatable along an outer circumferential surface of the shaft member, wherein a radial gap is provided between an outer circumferential surface of the shaft member and an inner circumferential surface of the outer ring portion,
Wherein the outer peripheral surface of the shaft member includes a first fluid dynamic pressure holding region disposed between the first surface region and the second surface region,
Wherein when the outer ring portion rotates from the first surface area along the outer circumferential surface of the shaft member to the second surface area through the first fluid dynamic pressure holding area, The first fluid dynamic pressure holding region and the second fluid dynamic pressure holding region are arranged such that in the first load bearing region located on the dynamic pressure holding region, the dynamic pressure can be generated by the fluid flowing from the first surface region to the first fluid dynamic pressure holding region in accordance with the rotation of the outer ring portion, And a dynamic pressure groove is formed in the surface area. The method according to claim 1,
Wherein when the outer ring portion rotates from the second surface area along the outer circumferential surface of the shaft member to the first surface area through the first fluid dynamic pressure holding area, Wherein a dynamic pressure groove is formed in the second surface area so as to generate a dynamic pressure by fluid flowing from the second surface area to the first fluid dynamic pressure holding area in accordance with rotation of the outer ring part. bearing. The method according to claim 1,
Wherein the dynamic pressure grooves of the first surface area are formed in a plurality of grooves having a substantially V shape and the vertex portions of the substantially V shape are formed so as to face the second surface area. 3. The method of claim 2,
Wherein the dynamic pressure grooves of the second surface area are formed by grooves having a plurality of substantially V shapes and the apexes of the substantially V shape are formed to face the first surface area. The method according to claim 1,
Wherein a plurality of dimples are formed on an outer peripheral surface of the shaft member in the first fluid dynamic pressure holding region. The method according to claim 1,
And an outer circumferential surface of the shaft member is formed with an arcuate groove along its circumferential direction. The method according to claim 1,
Wherein the outer race portion is provided with a passage hole communicating from the outer circumferential surface to the inner circumferential surface thereof. 8. The method according to any one of claims 2 to 7,
The outer peripheral surface of the shaft member further includes a third surface region, a fourth surface region, and a second fluid dynamic pressure holding region disposed between the third surface region and the fourth surface region,
Wherein when the outer ring portion rotates from the first surface area along the outer circumferential surface of the shaft member to the second surface area through the first fluid dynamic pressure holding area, A second fluid dynamic pressure holding region for holding the third fluid dynamic pressure holding region so as to be able to generate dynamic pressure by a fluid flowing from the third surface region to the second fluid dynamic pressure holding region in accordance with the rotation of the outer ring portion, A dynamic pressure groove is formed in the surface region,
Wherein when the outer ring portion rotates from the second surface region along the outer circumferential surface of the shaft member to the second surface area through the first fluid dynamic pressure holding region, Wherein a dynamic pressure groove is formed in the fourth surface region so that dynamic pressure can be generated by fluid flowing from the fourth surface region to the second fluid dynamic pressure holding region in accordance with rotation of the outer ring portion. bearing. 9. The method of claim 8,
Wherein the outer peripheral surface of the shaft member includes the third surface region and the fourth surface region on opposite sides of the axis of the shaft member of the first surface region and the second surface region, . The method according to claim 1,
Wherein the outer diameter of the outer peripheral surface of the shaft member is larger than the outer diameter of the insertion portion of the shaft member. The method according to claim 1,
Wherein the bearing is a cam follower or a roller follower. 1. A cam mechanism comprising a rotatable cam having a cam rib in a screw shape and a rotatable member rotatable in accordance with rotation of the cam,
The cam mechanism according to claim 1, wherein the rotating member has a plurality of hydrodynamic pressure bearings according to claim 1, and the cam rib is adapted to contact at least one of the plurality of fluid dynamic pressure bearings so that the rotating member rotates. 13. The method of claim 12,
Wherein each of said plurality of fluid dynamic pressure bearings has a first fluid dynamic pressure bearing region and a second fluid dynamic pressure bearing region, each of said plurality of fluid dynamic pressure bearings facing said cam rib when said cam rib contacts each of said plurality of fluid dynamic pressure bearings, And the shaft member is fixed to the rotating member. A cam mechanism comprising a rotatable planar cam and a member operable in accordance with rotation of the planar cam,
Wherein said member has a hydrodynamic bearing according to claim 1 at its tip and said member is adapted to operate by said planar cam contacting said hydrodynamic bearing. 15. The method of claim 14,
Characterized in that the shaft member of the fluid dynamic pressure bearing is fixed to the member so that the first fluid dynamic pressure holding region of the fluid dynamic pressure bearing faces the plane cam when the plane cam contacts the fluid dynamic pressure bearing .

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