JP6618757B2 - Fluid dynamic bearing - Google Patents

Description

  The present invention relates to a fluid dynamic pressure bearing that has high rotational accuracy and load capacity and is excellent in low torque performance.

  There is known a cam follower of a rolling bearing having a cylindrical outer ring, a stud inserted in the axial direction of the outer ring, and a roller that rolls between the outer ring and the stud as the outer ring rotates. There are a cam follower having a cage for holding a roller to be rolled, and a full-roller type cam follower without using a cage. Such a roller bearing cam follower is used for a cam mechanism such as a roller gear cam mechanism, a barrel cam mechanism, etc., but the outer ring outer diameter is restricted by the positional relationship with the cam, so that the rigidity and load capacity are insufficient. Tend to. Therefore, as an alternative to the cam follower of the rolling bearing, the stud diameter can be increased and the outer ring can be increased in thickness by using the slide bearing cam follower.

  Patent Document 1 discloses a cam follower including a shaft member whose one end is cantilevered and a slide bearing attached to the outer periphery of the other end of the shaft member. A plain bearing is composed of a cylindrical base made of a Fe-based sintered metal material having an Fe content of 90 wt% or more, and a sliding layer formed from the inner peripheral surface to both end faces of the base. The layer is formed of a sliding material composition in which a base material such as polyethylene resin is blended with a lubricant such as silicone oil and spherical porous silica impregnated with the lubricant.

  Patent Document 2 includes a bearing sleeve having a dynamic pressure groove region in which a plurality of dynamic pressure grooves are arranged in the circumferential direction on the inner periphery, and a shaft member inserted in the inner periphery of the bearing sleeve. A hydrodynamic bearing is disclosed in which a shaft member is supported in a non-contact radial direction in the forward / reverse rotation direction by the hydrodynamic action of a fluid generated in a radial bearing gap between an outer periphery and a hydrodynamic groove region on an inner periphery of a bearing sleeve. . The bearing sleeve is made of sintered metal, and has a first dynamic pressure groove region for one forward rotation on the one side in the axial direction and a first dynamic pressure groove region for the first reverse rotation on the other side in the axial direction. In addition, the first dynamic pressure groove region for forward rotation and the first dynamic pressure groove region for reverse rotation are respectively inclined with respect to the axial pressure direction, and are inclined in the opposite direction. A pressure groove is provided at another position in the axial direction.

JP-A-2005-24094 JP 2005-351374 A

  In the cam follower according to Patent Document 1, since the base of the slide bearing is formed of an Fe-based sintered metal material, high dimensional accuracy and rotational accuracy can be obtained, and polyethylene resin is used as a base material for the sliding layer. Since it is used and formed, it can have low friction. However, the coefficient of friction between the shaft member and the plain bearing is 0.08, which is larger than the coefficient of friction between the outer ring of the cam follower and the stud of the rolling bearing provided with the roller to be rolled. In addition, there is a problem that a large torque is required to rotate the plain bearing with respect to the shaft member, and the load capacity is small.

  The hydrodynamic bearing according to Patent Document 2 includes a hydrodynamic groove that is inclined with respect to the axial direction on the inner periphery of the bearing sleeve, and a hydrodynamic groove that is inclined in the opposite direction to the inner circumference of the bearing sleeve. Even during forward and reverse rotation, a fluid dynamic pressure action is generated in the radial bearing gap between the shaft member and the bearing sleeve. However, since it has a dynamic pressure groove region for forward rotation on one side in the axial direction and a dynamic pressure groove region for reverse rotation on the other side in the axial direction, fluid flows in the opposite direction in each region. Since it flows, there is a problem that it leaks to the outside of the bearing device and the friction between the shaft member and the bearing sleeve cannot be made sufficiently small.

  Accordingly, an object of the present invention is to provide a fluid dynamic bearing that solves the above-described problems, has high rotational accuracy, can be used without any problem even with a large load, and can reduce torque. That is.

  According to the present invention, the above object includes a shaft member and an outer ring portion that is rotatable along the outer peripheral surface of the shaft member, and a radial gap is provided between the outer peripheral surface of the shaft member and the inner peripheral surface of the outer ring portion. In the fluid dynamic pressure bearing provided, the outer peripheral surface of the shaft member is disposed between the first surface region, the second surface region, and the first surface region and the second surface region. A first fluid dynamic pressure holding region is included, and the outer ring portion is rotated along the outer peripheral surface of the shaft member from the first surface region to the second surface region through the first fluid dynamic pressure holding region. In the first load load region located on the first fluid dynamic pressure holding region in the radial gap, the first fluid dynamic pressure holding region is changed from the first surface region according to the rotation of the outer ring portion. A dynamic pressure groove is formed in the first surface region so that dynamic pressure can be generated by the fluid flowing in It is achieved by a fluid dynamic bearing that.

  Another object is to rotate the outer ring portion from the second surface region to the first surface region through the first fluid dynamic pressure holding region along the outer peripheral surface of the shaft member. In the first load application region, the dynamic pressure can be generated by the fluid flowing from the second surface region to the first fluid dynamic pressure holding region according to the rotation of the outer ring portion. This is achieved by a fluid dynamic pressure bearing in which dynamic pressure grooves are formed in the two surface regions.

  Another object of the above object is that the dynamic pressure groove in the first surface region is formed of a plurality of grooves having a substantially V shape, and the vertex portion of the substantially V shape is opposed to the second surface region. This is achieved by a fluid dynamic bearing that is configured to do so.

  In addition, another one of the above objects is that the dynamic pressure groove in the second surface region is formed from a plurality of grooves having a substantially V shape, and the apex portion of the substantially V shape faces the first surface region. This is achieved by a fluid dynamic bearing that is configured to do so.

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

  Another object is achieved by a fluid dynamic bearing in which an arc groove is formed on the outer peripheral surface of the shaft member along the circumferential direction thereof.

  Another of the above objects is achieved by a fluid dynamic bearing in which an outer passage portion is provided with an oil passage hole extending from the outer peripheral surface to the inner peripheral surface.

  Further, another one of the above objects is that the outer peripheral surface of the shaft member is further disposed between the third surface region, the fourth surface region, and the third surface region and the fourth surface region. A second fluid dynamic pressure holding region, and the outer ring portion extends from the first surface region along the outer peripheral surface of the shaft member to the second surface region through the first fluid dynamic pressure holding region. The second fluid dynamic pressure from the third surface region in accordance with the rotation of the outer ring portion in the second load load region located on the second fluid dynamic pressure holding region in the radial gap. A dynamic pressure groove is formed in the third surface region so that the dynamic pressure can be generated by the fluid flowing in the holding region, and the outer ring portion extends from the second surface region along the outer peripheral surface of the shaft member. The second load when rotating toward the first surface region through the one fluid dynamic pressure holding region. In the load region, a dynamic pressure groove is formed in the fourth surface region so that dynamic pressure can be generated by the fluid flowing from the fourth surface region to the second fluid dynamic pressure holding region in accordance with the rotation of the outer ring portion. This is achieved by a fluid dynamic pressure bearing.

  In addition, another one of the above objects is that the outer peripheral surface of the shaft member is a third surface region and a fourth surface region on the opposite sides of the first surface region and the second surface region with respect to the axis of the shaft member, respectively. Is achieved by a fluid dynamic pressure bearing including:

  Another of the above objects is achieved by a fluid dynamic 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 of the above objects is achieved by a fluid dynamic bearing that is a cam follower or a roller follower.

  Another object of the present invention is a cam mechanism including a rotatable cam having a screw-shaped cam rib and a rotating member that can rotate as the cam rotates. This is achieved by a cam mechanism that includes a plurality of dynamic pressure bearings, and the rotating member rotates when the cam rib contacts at least one of the plurality of fluid dynamic pressure bearings.

  Another object of the present invention is that when the cam rib contacts each of the plurality of fluid dynamic pressure bearings, the first fluid dynamic pressure holding region of each of the plurality of fluid dynamic pressure bearings faces the cam rib. In addition, this is achieved by a cam mechanism in which each shaft member of the plurality of fluid dynamic pressure bearings is fixed to the rotating member.

  Another object of the present invention is a cam mechanism including a rotatable planar cam and a member operable in accordance with the rotation of the planar cam, and the member is provided at the tip thereof with the fluid dynamic pressure bearing. And is achieved by a cam mechanism in which the member is operated by the planar cam contacting the fluid dynamic pressure bearing.

  Another object of the present invention is to provide a fluid dynamic pressure bearing such that the first fluid dynamic pressure holding region of the fluid dynamic pressure bearing faces the flat cam when the flat cam contacts the fluid dynamic pressure bearing. This is achieved by a cam mechanism in which the shaft member is fixed to the member.

As described above, by forming the dynamic pressure groove in the first surface region of the outer peripheral surface of the shaft member, the dynamic pressure due to the fluid is generated in the first load load region of the radial gap, and the shaft member and the outer ring Since the friction with the part can be reduced, the torque can be reduced, and there is an effect that it is possible to realize a bearing that has high rotational accuracy and can be used without any trouble even with a large load. . In addition, by forming a dynamic pressure groove in the second surface region of the outer peripheral surface of the shaft member, the first of the radial gaps in the case where the outer ring portion is rotated forward or backward with respect to the shaft member. There is an effect that the friction between the shaft member and the outer ring portion can be reduced by generating a dynamic pressure by the fluid in the load application region. Further, by making the dynamic pressure groove substantially V-shaped, there is an effect that the dynamic pressure can be generated more efficiently. Further, by forming the dimples and the arc grooves, there is an effect that the dynamic pressure can be generated more efficiently.
Further, by using the fluid dynamic pressure bearing of the present invention for the cam mechanism, it has high rotational accuracy and load capacity, is suitable for extending the life, and the fluid dynamic pressure bearing of the present invention has no rollers, so it is quiet. The cam mechanism with improved performance can be realized.

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

It is sectional drawing which looked at the fluid dynamic pressure bearing of this invention from the side surface. It is the schematic of the 1st Example seen from one side of the shaft member. It is the schematic of the 2nd Example seen from the one side of a shaft member. It is the schematic of the 3rd Example seen from the one side of a shaft member. It is the schematic of the 4th Example seen from one side of the shaft member. It is the schematic of the 5th Example seen from one side of the shaft member. It is the schematic of the 6th Example seen from the one side of a shaft member. It is the schematic of the 7th Example seen from the one side of a shaft member. It is the schematic of the 8th Example seen from the one side of the shaft member. It is the schematic of the 9th Example seen from one side of the shaft member. It is the schematic of the 10th Example seen from one side of a shaft member. It is the schematic of the 11th Example seen from one side of the shaft member. It is the schematic of the 1st Example seen from the opposite side surface of the shaft member. It is the schematic of the 2nd Example seen from the opposite side surface of the shaft member. It is sectional drawing seen from the front of an outer ring | wheel part. It is the partial perspective view seen from the side of an outer ring part. It is the schematic seen from the front of the cam mechanism using the fluid dynamic pressure bearing of this invention. It is the cross-sectional schematic which looked at the contact of the fluid dynamic pressure bearing of this invention and a cam surface from the lower surface. It is the schematic seen from the front of another cam mechanism using the fluid dynamic pressure bearing of this invention.

  Examples of the present invention will be described below with reference to the drawings, but the present invention is not limited to these examples.

  With reference to FIGS. 1-19, the Example of the fluid dynamic pressure bearing of this invention and the Example of the cam mechanism using the fluid dynamic pressure bearing of this invention are described.

  FIG. 1 shows a cross-sectional view of the fluid dynamic pressure bearing 101. The fluid dynamic pressure bearing 101 includes a shaft member 104 and an outer ring portion 102 that can rotate along the outer peripheral surface 107 of the shaft member 104. The fluid dynamic pressure bearing 101 includes an outer peripheral surface 107 of the shaft member 104 and an inner peripheral surface 120 of the outer ring portion 102. A radial gap 103 is provided between them. In FIG. 1, the fluid dynamic pressure bearing 101 further includes an insertion portion 105 for fitting the fluid dynamic pressure bearing 101 to a rotating member such as a turret of a cam mechanism, and a shaft member 104 on the turret via the insertion portion 105. Although the fixing member receiving hole 106 for receiving a fixing member such as a bolt for fixing is provided, the insertion portion 105 and the fixing member receiving hole 106 may not be provided.

  FIG. 2 shows a schematic diagram of the first embodiment of the shaft member 104 of the fluid dynamic bearing 101 shown in FIG. The outer peripheral surface 107 of the shaft member 104 includes a first surface region that is the first normal rotation dynamic pressure generation region 108, a second surface region that is the first reverse rotation dynamic pressure generation region 109, and a first normal rotation purpose. It includes a first fluid dynamic pressure holding region 110 disposed between the dynamic pressure generation region 108 and the first reverse rotation dynamic pressure generation region 109. In addition, the dotted line described in FIGS. 2-14 is a thing for convenience for demonstrating each area | region. The outer ring portion 102 moves from the first normal rotation dynamic pressure generation region 108 to the first reverse rotation dynamic pressure generation region 109 along the outer peripheral surface 107 of the shaft member 104 through the first fluid dynamic pressure holding region 110. In the first load load region (see FIG. 18) located on the first fluid dynamic pressure holding region 110 in the radial gap 103, the outer ring portion 102 The first normal rotation dynamic pressure generation region so that the dynamic pressure can be generated by fluid such as oil flowing from the first normal rotation dynamic pressure generation region 108 to the first fluid dynamic pressure holding region 110 according to the rotation. A dynamic pressure groove 111 that is recessed with respect to the outer peripheral surface 107 is formed in 108. As described above, when the dynamic pressure groove 111 is formed in the first normal rotation dynamic pressure generation region 108, fluid such as oil is generated according to the normal rotation of the outer ring portion 102. The fluid flows along the dynamic pressure groove 111 in the region 108 toward the first fluid dynamic pressure holding region 110 so as to be concentrated at the tip end portion of the dynamic pressure groove 111, and the aggregated fluid is dammed at the tip end portion. By being stopped, in the first load load region located on the first fluid dynamic pressure holding region 110 in the radial gap 103, a film with a high pressure fluid is formed, and dynamic pressure due to the fluid is generated. . Due to the dynamic pressure of the fluid, the outer ring portion 102 can rotate with low friction and low torque without contacting the shaft member 104 in the first fluid dynamic pressure holding region 110.

  Further, the outer ring portion 102 passes from the first reverse rotation dynamic pressure generation region 109 through the first fluid dynamic pressure holding region 110 along the outer peripheral surface 107 of the shaft member 104 to the first forward rotation dynamic pressure generation region 108. In the first load application region (see FIG. 18) located on the first fluid dynamic pressure holding region 110 in the radial gap 103. The first reverse dynamic pressure 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 according to the rotation of 102. A dynamic pressure groove 111 that is recessed with respect to the outer peripheral surface 107 may be formed in the generation region 109. As described above, when the dynamic pressure groove 111 is formed in the first reverse rotation dynamic pressure generation region 109, fluid such as oil is generated according to the reverse rotation of the outer ring portion 102. The fluid flows along the dynamic pressure groove 111 in the region 109 toward the first fluid dynamic pressure holding region 110 so as to be concentrated at the tip end portion of the dynamic pressure groove 111, and the aggregated fluid is dammed by the tip end portion. By being stopped, in the first load load region located on the first fluid dynamic pressure holding region 110 in the radial gap 103, a film with a high pressure fluid is formed, and dynamic pressure due to the fluid is generated. Due to the dynamic pressure of the fluid, the outer ring portion 102 can rotate with low friction and low torque without contacting the shaft member 104 in the first fluid dynamic pressure holding region 110.

  The first surface region dynamic pressure groove 111 that is the first normal rotation dynamic pressure generation region 108 may be formed of a plurality of substantially V-shaped grooves, and the substantially V-shaped apex portion is the first portion. 1 may be formed so as to face the reverse rotation dynamic pressure generation region 109. In addition, the dynamic pressure groove 111 in the second surface region, which is the first reverse rotation dynamic pressure generation region 109, may be formed of a plurality of substantially V-shaped grooves, and the substantially V-shaped apex portion thereof. May be formed to face the first normal rotation dynamic pressure generation region 108. By making the dynamic pressure groove 111 into a groove having a substantially V shape, the fluid flows so as to be concentrated at the apex portion 112 which is a substantially V-shaped pointed portion, and the aggregated fluid is the apex portion 112. In the radial gap 103, a film with a high pressure fluid is formed in the first load load region located on the first fluid dynamic pressure holding region 110 in the radial gap 103, and the dynamic pressure due to the fluid is generated. To do.

  Then, a substantially V-shaped apex portion 112 that is the dynamic pressure groove 111 of the first normal rotation dynamic pressure generation region 108 and a substantially V shape that is the dynamic pressure groove 111 of the first reverse rotation dynamic pressure generation region 109. By forming the apex portions 112 of the shapes so as to face each other, the first fluid movement in the radial gap 103 can be performed regardless of whether the outer ring portion 102 rotates forward or reversely. A film made of a fluid having a high pressure can be formed in the first load application region located on the pressure holding region 110.

  As shown in FIG. 3, one or more arc grooves 114 may be formed on the outer peripheral surface 107 of the shaft member 104 along the circumferential direction of the outer peripheral surface 107. Further, the arc groove 114 may be formed so as to connect the substantially V-shaped apex portion 112 which is the pointed portion of the dynamic pressure groove 111, and when formed in this way, the first normal rotation dynamic pressure generation region 108 is formed. In the dynamic pressure groove 111 of the first reverse rotation dynamic pressure generation region 109, herringbone-shaped grooves facing each other are formed. By forming the arc groove 114 on the outer peripheral surface 107 of the shaft member 104, the fluid is more efficiently concentrated, and a film made of a fluid having a high pressure is formed in the first load load region, and dynamic pressure is generated by the fluid. To do.

  As shown in FIG. 4, the first fluid dynamic pressure holding region between the first normal rotation dynamic pressure generation region 108 and the first reverse rotation dynamic pressure generation region 109 is formed on the outer peripheral surface 107 of the shaft member 104. 110, a plurality of concave dimples 113 may be formed. The outer diameter of the dimple 113 is 100 μm or less, preferably 50 μm or less. By forming a plurality of dimples 113 in the first fluid dynamic pressure holding region 110, when the outer ring portion 102 is rotating forward or backward with respect to the shaft member 104, the plurality of dimples 113 are It acts as a pool of fluid flowing in from the normal rotation dynamic pressure generation region 108 or the first reverse rotation dynamic pressure generation region 109 toward the first fluid dynamic pressure holding region 110, thereby improving the fluid film forming ability. Can be made. For this reason, in the first load load region located on the first fluid dynamic pressure holding region 110 in the radial gap 103, a film made of a fluid with higher pressure is formed, and dynamic pressure due to the fluid is generated. To do. Due to the dynamic pressure of the fluid, the outer ring portion 102 can rotate with low friction and low torque without contacting the shaft member 104 in the first fluid dynamic pressure holding region 110. As shown in FIG. 4, the dimple 113 may be formed in the first normal rotation dynamic pressure generation region 108 and the first reverse rotation dynamic pressure generation region 109, or the outer peripheral surface 107 of the shaft member 104. It may be formed entirely.

  5 to 10 show the fourth to ninth embodiments. FIG. 5 shows an embodiment in which dimples 113 are formed with respect to the embodiment of FIG. 3, and FIG. 6 increases the number of dynamic pressure grooves 111 and arc grooves formed with respect to the embodiment of FIG. 7 is an embodiment in which dimples 113 are formed with respect to the embodiment of FIG. 6, and FIG. 8 is an embodiment in which the arc groove 114 of the embodiment of FIG. 6 is formed in an annular shape. 9 is an embodiment in which dimples 113 are formed with respect to the embodiment of FIG. 8, and FIG. 10 is an embodiment showing other shapes of the dynamic pressure grooves. In this way, dynamic pressure can be generated by combining dynamic pressure grooves, arc grooves, and dimples of any shape, and there are various types depending on the environment in which the fluid dynamic pressure bearing is used, such as the magnitude of moment load. The shape can be selected. The shapes of the dynamic pressure grooves, the arc grooves, and the dimples formed in the outer peripheral portion 107 are not limited to these examples.

  2 to 10, the dynamic pressure groove 111 of the first normal rotation dynamic pressure generation region 108 and the dynamic pressure groove 111 of the first reverse rotation dynamic pressure generation region 109 are the axis 104a of the shaft member 104 shown in FIG. However, as shown in FIGS. 11 and 12, the first normal rotation dynamic pressure generation region 108, the first reverse rotation dynamic pressure generation region 109, the first The 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 α with respect to the axis 104 a of the shaft member 104. Further, the dimples 113 may be formed so as to be distributed so as to have an angle α with respect to the axis 104a. Note that the angle α causes the dynamic pressure due to the fluid to be generated in the portion where the outer ring portion 102 of the fluid dynamic pressure bearing 101 is most pressed when the fluid dynamic pressure bearing 101 is used in the cam mechanism as described later. Is determined to be able to. By having the angle α in this way, there is an effect that the friction between the shaft member 104 and the outer ring portion 102 can be reduced according to 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 further provided with a second normal rotation dynamic pressure generation region 115 that is a third surface region, and a second reverse rotation direction that is a fourth surface region. The dynamic pressure generation region 116 may include a second fluid dynamic pressure holding region 117 disposed between the second forward dynamic pressure generation region 115 and the second reverse dynamic pressure generation region 115. The outer ring portion 102 travels from the second normal rotation dynamic pressure generation region 115 through the second fluid dynamic pressure holding region 117 to the second reverse rotation dynamic pressure generation region 116 along the outer peripheral surface 107 of the shaft member 104. In other words, that is, the first reverse dynamic pressure through the first fluid dynamic pressure holding region 110 from the first normal dynamic pressure generation region 108 along the outer peripheral surface 107 of the shaft member 104. When rotating toward the generation region 109 (forward rotation), in the second load load region (see FIG. 18) located on the second fluid dynamic pressure holding region 117 in the radial gap 103. The second positive pressure is generated by the fluid such as oil flowing from the second forward dynamic pressure generating region 115 to the second fluid dynamic pressure holding region 117 according to the rotation of the outer ring portion 102. Outside the diversion dynamic pressure generation region 115 Recessed in which dynamic pressure grooves 111 may be formed with respect to the surface 107. Further, the outer ring portion 102 passes through the second fluid dynamic pressure holding region 117 from the second reverse dynamic pressure generating region 116 along the outer peripheral surface 107 of the shaft member 104, and the second normal rotation dynamic pressure generating region 115. In other words, that is, the first forward rotation direction from the first reverse rotation dynamic pressure generation region 109 through the first fluid dynamic pressure holding region 110 along the outer peripheral surface 107 of the shaft member 104. When rotating toward the dynamic pressure generation region 108 (reverse rotation), the second load load region located on the second fluid dynamic pressure holding region 117 in the radial gap 103 (see FIG. 18). ), The second dynamic pressure can be generated by a fluid such as oil flowing from the second reverse dynamic pressure generation region 116 to the second fluid dynamic pressure holding region 117 according to the rotation of the outer ring portion 102. Dynamic pressure generation region 11 for reverse rotation Dynamic pressure groove 111 is recessed relative to the outer peripheral surface 107 may be formed on. As described above, when the dynamic pressure groove 111 is formed in the second normal rotation dynamic pressure generation region 115 and the dynamic pressure groove 111 is formed in the second reverse rotation dynamic pressure generation region 116, the positive pressure of the outer ring portion 102 is increased. In response to the rotation or reverse rotation, the fluid flows into the second fluid dynamic pressure holding region 117 along the dynamic pressure groove 111 of the second forward dynamic pressure generation region 115 or the second reverse dynamic pressure generation region 116. The first fluid dynamic pressure holding region in the radial gap 103 is flowed so as to be concentrated at the tip of the dynamic pressure groove 111 and the collected fluid is dammed up at the tip. Also in the second load load region (see FIG. 18) located on the second fluid dynamic pressure holding region 117 arranged at a position different from 110, a film with a high-pressure fluid is formed, and the dynamic pressure by the fluid Will occur. Due to the dynamic pressure due to the fluid, the outer ring portion 102 can rotate with low friction and low torque without contacting the shaft member 104 even in the second fluid dynamic pressure holding region 117.

  The second normal rotation dynamic pressure generation region 115 may be disposed on the opposite side of the first normal rotation dynamic pressure generation region 108 with respect to the axis 104a of the shaft member 104 shown in FIG. Further, the second reverse rotation dynamic pressure generation region 116 may be disposed on the opposite side of the first reverse rotation dynamic pressure generation region 109 with respect to the axis 104a of the shaft member 104 shown in FIG.

  As shown in FIG. 1, when the insertion portion 105 is provided, 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. By making the outer diameter of the outer peripheral surface 107 larger than the outer diameter of the insertion portion 105, when the fluid dynamic pressure bearing 101 is fitted to a rotating member such as a turret of the cam mechanism, the outer peripheral surface 107 does not enter the rotating member too much. Thus, the length of the outer peripheral surface 107 with respect to the direction of the axis 104a of the shaft member 104 can be secured, and the outer ring portion 102 can smoothly rotate along the outer peripheral surface 107 of the shaft member 104. I am doing so.

  As shown in FIGS. 15 and 16, the outer ring portion 102 may be provided with an oil passage hole 118 that communicates from the outer peripheral surface 119 of the outer ring portion 102 to the inner peripheral surface 120. By providing the oil passage hole 118, fluid such as oil can be smoothly passed from the outer peripheral surface 119 of the outer ring portion 102 to the radial gap 103 between the outer peripheral surface 107 of the shaft member 104 and the inner peripheral surface 120 of the outer ring portion 102. It becomes possible to flow in and out.

  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 the fluid dynamic pressure bearing 101 is used. As shown in FIG. 17, the cam mechanism 201 includes a cam 202 that can rotate around a cam axis 203 having screw-shaped cam ribs 204 on all or part of the cam shaft, and a rotating member axis along with the rotation of the cam 202. And a rotating member 207 such as a turret that can rotate around 208. FIG. 17 shows a speed reduction mechanism using a roller gear (globoidal) cam as a cam mechanism. Other cam mechanisms such as a linear motion mechanism and a swing mechanism using a planar cam may be used. The rotating member 207 is provided with a plurality of fluid dynamic pressure bearings 101 along the outer peripheral direction thereof. In order to attach the fluid dynamic pressure bearing 101 to the rotating member 207 of the cam mechanism 201, for example, the fluid dynamic pressure bearing 101 is inserted into the rotating member 207 via the insertion portion 105 of the shaft member 104, and the fixed member receiving hole 106 is inserted. A method of fixing the shaft member 104 to the rotating member 207 by inserting a fixing member such as a bolt and fastening it to the rotating member 207, inserting the insertion portion 105 of the fluid dynamic pressure bearing 101 into the rotating member 207, and inserting the rotating member 207 A method of fixing the shaft member 104 to the rotating member 207 by inserting a set screw into a female screw provided at a position where the portion 105 is inserted (in this case, the insertion portion 105 has a recess having a flat bottom, V And a method of fixing by inserting the insertion portion 105 of the fluid dynamic pressure bearing 101 into the rotary member 207 by press fitting (fitting). How to Sukimabameshi the insertion portion 105 of the fluid dynamic bearing 101 relative to the rotary member 207, to introduce the screw locking adhesive to gaps fixing, etc., these are a variety of ways including, but not limited. When the cam 202 rotates, the outer peripheral surface 119 of the fluid dynamic pressure bearing 101 is brought into contact with the first cam surface 205 or the second cam surface 206 of the cam rib 204 and the outer peripheral surface 119 of the outer ring portion 102 of the fluid dynamic pressure bearing 101. The rotating member 207 rotates by being pressed. At this time, the outer ring portion 102 of the fluid dynamic pressure bearing 101 is supported by the shaft member 104 and can rotate, so that it is in rolling contact with the cam rib 204. .

  FIG. 18 is a schematic cross-sectional view showing a contact state between the outer peripheral 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 a certain timing of the cam mechanism. . When the cam rib 204 rotates along the direction of the arrow as the cam 202 rotates, the outer ring portion 102 of the fluid dynamic pressure bearings 101 a and 101 c that are in rolling contact with the cam 202 is in the direction of the arrow ( 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 101 a, and the center axis of the outer ring portion 102 is in relation to the center axis of the shaft member 104. In the inclined state, the outer ring portion 102 is supported by the shaft member 104 and passes through the first fluid dynamic pressure holding region 110 from the first forward dynamic pressure generating region 108 to the first reverse dynamic pressure generating region. Rotate clockwise to 109. The fluid in the radial gap 103 also flows from the first normal rotation dynamic pressure generation region 108 to the first fluid dynamic pressure holding region 110 according to the rotation of the outer ring portion 102. Here, the load on the outer peripheral surface 107 of the shaft member 104 due to the pressing from the first cam surface 205 to the outer ring portion 102 is limited to the portion facing the first cam surface 205. Therefore, a film made of a fluid having a high pressure is formed on a portion of the outer peripheral surface 107 of the shaft member 104 facing the first cam surface 205 to generate a dynamic pressure by the fluid, so that the shaft member 104 and the outer ring portion 102 are formed. It is necessary to reduce the friction with. Therefore, the first fluid dynamic pressure holding region in which the shaft member 104 is disposed between the first normal rotation dynamic pressure generation region 108 and the first reverse rotation dynamic pressure generation region 109 included in the outer peripheral surface 107 thereof. If 110 is fixed to the rotating member 207 so as to face the first cam surface 205, in the first load load region 121 located on the first fluid dynamic pressure holding region 110 in the radial gap 103, Dynamic pressure due to fluid can be generated, and friction between the shaft member 104 and the outer ring portion 102 can be reduced. In addition, the cam 202 rotates in the reverse direction, and the outer ring portion 102 is supported by the shaft member 104 while passing through the first fluid dynamic pressure holding region 110 from the first reverse rotation dynamic pressure generating region 109. Even in the case of rotating counterclockwise toward the generation region 108, similarly, the dynamic pressure due to the fluid can be generated in the first load application region 121.

  17 and 18, when the rotation direction of the outer ring portion 102 of the fluid dynamic pressure bearing 101a is different from the rotation direction of the outer ring portion 102 of the fluid dynamic pressure bearing 101c, the fluid dynamic pressure bearing 101b is formed on the cam rib 204. You may make it not contact.

  The fluid dynamic pressure bearing 101c is in contact with the second cam surface 206 opposite to the first cam surface 205, that is, in contact with the cam surface opposite to the cam surface with which the fluid dynamic pressure bearing 101a contacts. Yes. Here, as with the fluid dynamic pressure bearing 101 a, the load on the outer peripheral surface 107 of the shaft member 104 due to the pressing from the second cam surface 206 to the outer ring portion 102 faces the second cam surface 206. It is limited to the part. Accordingly, in order to form a film made of a fluid having a high pressure on the portion of the outer circumferential surface 107 of the shaft member 104 facing the second cam surface 206 and to generate a dynamic pressure due to the fluid, the outer circumferential surface 107 is further provided. The second normal rotation dynamic pressure generation region 115, the second reverse rotation dynamic pressure generation region 116, and the second normal rotation dynamic pressure generation region 115 and the second reverse rotation dynamic pressure generation region 116 are arranged. The second fluid dynamic pressure holding region 117 may be included. Then, the second fluid dynamic pressure holding region in which the shaft member 104 is disposed between the second normal rotation dynamic pressure generation region 115 and the second reverse rotation dynamic pressure generation region 116 included in the outer peripheral surface 107 thereof. If 117 is fixed to the rotating member 207 so as to face the second cam surface 206, the second fluid dynamic pressure is maintained from the second reverse dynamic pressure generating region 116 while the outer ring portion 102 is supported by the shaft member 104. Even when rotating counterclockwise through the region 117 toward the second normal rotation dynamic pressure generating region 115, the cam 202 rotates in the reverse direction and the outer ring portion 102 is supported by the shaft member 104, while Even when the forward rotation dynamic pressure generation region 115 rotates clockwise through the second fluid dynamic pressure holding region 117 and toward the second reverse rotation dynamic pressure generation region 116, 2 Fluid dynamic pressure holding area In the second load bearing region 122 located above 117, it is possible to generate a dynamic pressure by the fluid, it is possible to reduce the friction between the shaft member 104 and the outer ring portion 102.

  FIG. 19 shows another cam mechanism 301 in which the fluid dynamic pressure bearing 101 is used. As shown in FIG. 19, the cam mechanism 301 includes a planar cam 302 that can rotate around the planar cam axis 303 and a member 304 that can operate as the planar cam 302 rotates. The planar cam 302 may be a plate cam, a groove cam, or the like. The member 304 is provided with a fluid dynamic pressure bearing 101 at its tip. When 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 flat cam 302 rotates around the flat cam axis 303, the fluid dynamic bearing 101 provided at the tip of the member 304 comes into contact with the end or groove of the flat cam 302, The member 304 linearly moves up and down with the contact by rotation. When the flat cam 302 and the fluid dynamic pressure bearing 101 are in contact, the outer ring portion 102 of the fluid dynamic pressure bearing 101 rotates relative to the shaft member 104 of the fluid dynamic pressure bearing 101 fixed to the tip of the member 304. doing.

  Further, when the flat cam 302 and the fluid dynamic pressure bearing 101 are in contact with each other, it is the flat cam 302 that receives a load on the outer peripheral surface 107 of the shaft member 104 due to the pressing from the flat cam 302 to the outer ring portion 102. It is a part facing the end and the groove. Therefore, when the flat cam 302 is in contact with the fluid dynamic pressure bearing 101, the first normal rotation dynamic pressure generation region 108 and the first reverse rotation dynamic pressure generation region included in the outer peripheral surface 107 of the shaft member 104 are provided. 109, the shaft member 104 of the fluid dynamic pressure bearing 101 may be fixed to the member 304 so that the first fluid dynamic pressure holding region 110 disposed between the first and second members 109 faces the end of the flat cam 302 and the groove. . By fixing the shaft member 104 in this way, it is possible to generate dynamic pressure due to fluid in the first load load region located on the first fluid dynamic pressure holding region 110 in the radial gap 103. The friction between the shaft member 104 and the outer ring portion 102 can be reduced.

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

DESCRIPTION OF SYMBOLS 101 Fluid dynamic pressure bearing 102 Outer ring | wheel part 103 Radial clearance 104 Shaft member 105 Insertion part 106 Fixed member receiving hole 107 Outer peripheral surface of a shaft member 108 1st normal rotation dynamic pressure production | generation area | region (1st surface area)
109 First dynamic pressure generation region for reverse rotation (second surface region)
110 First fluid dynamic pressure holding region 111 Dynamic pressure groove 112 Dynamic pressure groove apex 113 Dimple 114 Arc groove 115 Second normal rotation dynamic pressure generation region (third surface region)
116 Second dynamic pressure generation region for reverse rotation (fourth surface region)
117 Second fluid dynamic pressure holding region 118 Oil passage hole 119 Outer ring outer peripheral surface 120 Outer ring inner peripheral surface 121 First load load region 122 Second load load region 201 Cam mechanism 202 Cam 203 Cam axis 204 Cam rib 205 First 1 Cam surface 206 Second cam surface 207 Rotating member 208 Rotating member axis 301 Cam mechanism 302 Planar cam 303 Planar cam axis 304 Member

Claims (15)

A fluid dynamic pressure bearing for a cam mechanism comprising a rotatable cam having a cam rib and a rotatable rotating member, or a cam mechanism comprising a rotatable planar cam and an operable member,
The fluid dynamic pressure bearing includes a shaft member and an outer ring portion rotatable along the outer peripheral surface of the shaft member, and a radial gap is formed between the outer peripheral surface of the shaft member and the inner peripheral surface of the outer ring portion. Provided ,
The outer peripheral surface of the front Kijiku member has a first surface region, a second surface region, and the first fluid dynamic retention disposed between the first surface region and the second surface region Including areas,
When the outer ring portion rotates along the outer peripheral surface of the shaft member from the first surface region through the first fluid dynamic pressure holding region toward the second surface region, In the first load application region located on the first fluid dynamic pressure holding region in the radial gap, the first surface region is changed to the first fluid dynamic pressure holding region according to the rotation of the outer ring portion. A dynamic pressure groove is formed in the first surface region so that dynamic pressure can be generated by the flowing fluid ,
When the rotatable rotating member includes the fluid dynamic pressure bearing, when the cam rib comes into contact with the fluid dynamic pressure bearing, the first fluid dynamic pressure holding region faces the cam rib. The shaft member is fixed to the rotatable rotating member;
When the operable member includes the fluid dynamic pressure bearing, the first fluid dynamic pressure holding region faces the planar cam when the planar cam contacts the fluid dynamic pressure bearing. fluid dynamic bearing, wherein Rukoto said shaft member is fixed to the operable member.   When the outer ring portion rotates along the outer peripheral surface of the shaft member from the second surface region to the first surface region through the first fluid dynamic pressure holding region, In the first load application region, the second pressure is generated so that dynamic pressure can be generated by the fluid flowing from the second surface region to the first fluid dynamic pressure holding region in accordance with the rotation of the outer ring portion. The fluid dynamic pressure bearing according to claim 1, wherein a dynamic pressure groove is formed in a surface region of the fluid dynamic bearing.   The dynamic pressure groove of the first surface region is formed from a plurality of grooves having a substantially V shape, and the apex portion of the substantially V shape is formed to face the second surface region. The fluid dynamic pressure bearing according to claim 1.   The dynamic pressure groove of the second surface region is formed from a plurality of grooves having a substantially V shape, and the vertex portion of the substantially V shape is formed to face the first surface region. The fluid dynamic pressure bearing according to claim 2.   5. The fluid dynamic pressure bearing 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 fluid dynamic pressure bearing according to any one of claims 1 to 5, wherein an arc groove is formed on an outer peripheral surface of the shaft member along a circumferential direction thereof.   The fluid dynamic pressure bearing according to any one of claims 1 to 6, wherein an oil passage hole is provided in the outer ring portion from the outer peripheral surface to the inner peripheral surface. The outer peripheral surface of the shaft member is further provided with a third surface region, a fourth surface region, and a second fluid dynamic pressure disposed between the third surface region and the fourth surface region. Including holding areas,
When the outer ring portion rotates along the outer peripheral surface of the shaft member from the first surface region through the first fluid dynamic pressure holding region toward the second surface region, In the second load application region located on the second fluid dynamic pressure holding region in the radial gap, the third surface region is changed to the second fluid dynamic pressure holding region according to the rotation of the outer ring portion. A dynamic pressure groove is formed in the third surface region so that dynamic pressure can be generated by the flowing fluid,
When the outer ring portion rotates along the outer peripheral surface of the shaft member from the second surface region to the first surface region through the first fluid dynamic pressure holding region, In the second load application region, the fourth pressure is generated so that dynamic pressure can be generated by the fluid flowing from the fourth surface region to the second fluid dynamic pressure holding region in accordance with the rotation of the outer ring portion. The fluid dynamic pressure bearing according to any one of claims 2 to 7, wherein a dynamic pressure groove is formed in the surface region of the fluid.   The outer peripheral surface of the shaft member includes the third surface region and the fourth surface region on opposite sides of the first surface region and the second surface region with respect to the axis of the shaft member, respectively. The fluid dynamic pressure bearing according to claim 8.   The fluid dynamic pressure bearing according to claim 1, wherein an outer diameter of an outer peripheral surface of the shaft member is larger than an outer diameter of an insertion portion of the shaft member.   It is a cam follower or a roller follower, The fluid dynamic pressure bearing as described in any one of Claims 1-10 characterized by the above-mentioned. A rotatable cam having a mosquito Muribu, a cam mechanism and a rotation that can be rotated member,
The rotating member includes a plurality of fluid dynamic pressure bearings according to any one of claims 1 to 11, and the cam rib contacts at least one of the plurality of fluid dynamic pressure bearings, whereby the rotating member and the a cam mechanism, characterized in that the cam is rotated.   The plurality of fluids so that the first fluid dynamic pressure holding region of each of the plurality of fluid dynamic pressure bearings faces the cam rib when the cam rib contacts each of the plurality of fluid dynamic pressure bearings. The cam mechanism according to claim 12, wherein each shaft member of the hydrodynamic bearing is fixed to the rotating member. A cam mechanism comprising a flat cam rotatable, and that can operate member,
The said member is equipped with the fluid dynamic pressure bearing as described in any one of Claims 1-11 in the front-end | tip, The said member operate | moves when the said plane cam contacts the said fluid dynamic pressure bearing, and the said plane cam A cam mechanism characterized in that is configured to rotate .   When the planar cam contacts the fluid dynamic pressure bearing, the shaft member of the fluid dynamic pressure bearing is arranged such that the first fluid dynamic pressure holding region of the fluid dynamic pressure bearing faces the planar cam. The cam mechanism according to claim 14, wherein the cam mechanism is fixed to the member.