TWI708018B - A fluid hydrodynamic bearing and cam mechanism having the same - Google Patents

Abstract

Provides flow with high rotation accuracy and load capacity, and excellent low torque Body dynamic pressure bearing.

The hydrodynamic bearing is equipped with a shaft member and can be relative to the shaft The outer ring part where the member rotates is provided with a radial gap between the shaft member and the outer ring part. The outer peripheral surface of the shaft member includes the first surface area, the second surface area, and the first fluid dynamic pressure holding area, in the first surface area A dynamic pressure groove is formed on the outer ring so that when the outer ring portion is rotated relative to the shaft member from the first surface area through the first fluid dynamic pressure holding area toward the second surface area, the radial gap can be located at the first In the first load-carrying area on the fluid dynamic pressure holding area, dynamic pressure is generated by the fluid flowing from the first surface area to the first fluid dynamic pressure holding area.

Description

Fluid dynamic pressure bearing and cam mechanism with the fluid dynamic pressure bearing Invention field

The present invention relates to a hydrodynamic bearing having high rotation accuracy and load capacity, and excellent low torque.

Background of the invention

A cam follower with a cylindrical outer ring, a stud inserted into the outer ring in the direction of the axis, and a roller bearing between the outer ring and the stud that rotates with the rotation of the outer ring is well known. Among them, there are a cam follower equipped with a retainer for holding a rotatable roller, and a full roller type cam follower that does not use a retainer. The cam follower of this rolling bearing can be used in cam mechanisms, such as roller gear cam mechanisms, drum cam mechanisms, etc. However, due to the positional relationship with the cam, the outer diameter of the outer ring is limited, so there is insufficient rigidity or insufficient load capacity Propensity. Therefore, by using the cam follower of the sliding bearing as a substitute for the cam follower of the rolling bearing, the outer diameter of the stud can be enlarged or the thickness of the outer ring can be thickened.

Patent Document 1 discloses a cam follower that includes a shaft member whose one end is cantilevered and is mounted on the outer periphery of the other end of the shaft member Of sliding bearings. The sliding bearing is composed of a cylindrical matrix and a sliding layer. The cylindrical matrix is composed of an Fe-based sintered metal material with a Fe content of 90wt% or more. The sliding layer is formed from the inner peripheral surface of the matrix. The sliding layer is formed on both end surfaces, and the sliding layer is formed of a sliding material composition in which a lubricant such as silicone oil is mixed with a base material such as polyethylene resin and spherical porous silica impregnated with the lubricant.

Patent Document 2 discloses a dynamic pressure bearing including 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 circumference, and a shaft member inserted into the inner circumference of the bearing sleeve , And use the dynamic pressure of the fluid generated by the radial bearing gap between the outer circumference of the shaft member and the inner circumference of the bearing sleeve to support the shaft member in a non-contact direction in both the forward and reverse directions. In the radial direction. The bearing sleeve is made of sintered metal, and the inner circumference has a first dynamic pressure groove area for forward rotation on one side of the axial direction and a first dynamic pressure groove area for reverse rotation on the other side of the axial direction. The dynamic pressure groove region for use and the dynamic pressure groove region for the first reversal are each provided with a dynamic pressure groove inclined with respect to the axial direction at different positions in the axial direction, and a dynamic pressure inclined in the opposite direction. Groove.

Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2005-24094

Patent Document 2: Japanese Patent Laid-Open No. 2005-351374

Summary of the invention

In the cam follower in Patent Document 1, the base body of the sliding bearing is formed of Fe-based sintered metal material, so high dimensional accuracy can be obtained In addition, the sliding layer is formed using polyethylene resin as a base material, and therefore can have low friction properties. However, the friction coefficient between the shaft member and the sliding bearing is 0.08, which is larger than the friction coefficient between the outer ring of the cam follower and the stud of the rolling bearing with rotatable rollers, so When the sliding bearing rotates relative to the shaft member, a large torque is required, and there is a problem of a small load capacity.

The dynamic pressure bearing in Patent Document 2 has dynamic pressure grooves inclined with respect to the axial direction at different positions in the axial direction on the inner circumference of the bearing sleeve, and dynamic pressure grooves inclined in the opposite direction to the inner circumference of the bearing sleeve. During forward or reverse rotation, it will generate dynamic pressure of fluid in the radial bearing gap between the shaft member and the bearing sleeve. However, since there is a dynamic pressure groove area for forward rotation on one side of the axial direction and a dynamic pressure groove area for reverse rotation on the other side of the axial direction, fluid will flow in the reverse direction in each area, so there is leakage to It is a problem that the friction between the shaft member and the bearing sleeve cannot be sufficiently reduced on the outside of the bearing device.

Therefore, the purpose of the present invention is to solve the above-mentioned problems and provide a hydrodynamic bearing that has high rotation accuracy, can be used without obstacles under heavy loads, and can reduce torque.

According to the present invention, the above-mentioned object is achieved by a hydrodynamic bearing provided with a shaft member and an outer ring portion rotatable along the outer peripheral surface of the shaft member. A radial gap is provided between the outer circumferential surface of the shaft member and the inner circumferential surface of the outer ring portion. The outer circumferential surface of the shaft member includes the first surface area, the second surface area, and the first surface area and the second surface area. Of The first fluid dynamic pressure holding area is formed in the first surface area, and a dynamic pressure groove is formed on the first surface area to rotate the outer ring portion along the outer peripheral surface of the shaft member and pass the first fluid dynamic pressure from the first surface area When the holding area faces the second surface area, it is possible to flow from the first surface area to the first load bearing area on the first hydrodynamic pressure holding area in the radial gap as the outer ring portion rotates. The first fluid dynamic pressure maintains the fluid in the region to generate dynamic pressure.

In addition, another object of the above-mentioned object is achieved by a fluid dynamic pressure bearing in which a dynamic pressure groove is formed in the second surface area to rotate the outer ring part along the outer peripheral surface of the shaft member from the first 2 When the surface area passes through the first hydrodynamic pressure holding area toward the first surface area, the first load bearing area can flow from the second surface area to the first hydrodynamic pressure holding area as the outer ring portion rotates. The fluid in the area generates dynamic pressure.

In addition, another object of the above-mentioned object is achieved by a fluid dynamic pressure bearing in which the dynamic pressure groove in the first surface area is formed by a plurality of grooves having a substantially V-shape, and is formed into a substantially V The vertex of the character shape faces the second surface area.

In addition, another object of the above-mentioned object is achieved by a fluid dynamic pressure bearing in which the dynamic pressure grooves in the second surface area are formed by a plurality of grooves having a substantially V shape, and are formed into substantially V The vertex of the character shape faces the first surface area.

In addition, another object of the above-mentioned object 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 area.

Also, another purpose of the above purpose is to use a fluid The pressure bearing is achieved by forming a circular arc groove on the outer peripheral surface of the shaft member along its circumferential direction.

In addition, another purpose of the above-mentioned object is achieved by a hydrodynamic bearing in which an oil passage hole is provided in the outer ring portion from the outer peripheral surface to the inner peripheral surface.

In addition, another object of the above-mentioned object is achieved by a hydrodynamic bearing, which is to make the outer peripheral surface of the shaft member further include a third surface area, a fourth surface area, and are arranged on the third surface area and the fourth surface The second fluid dynamic pressure holding area between the areas, and a dynamic pressure groove is formed on the third surface area, so that the outer ring portion is rotated to follow the outer peripheral surface of the shaft member and pass the first fluid through the first surface area When the dynamic pressure holding area faces the second surface area, the second load bearing area on the second fluid dynamic pressure holding area in the radial gap can be removed from the third surface area as the outer ring portion rotates. The fluid flowing to the second fluid dynamic pressure holding area generates dynamic pressure; and a dynamic pressure groove is formed in the fourth surface area to rotate the outer ring portion along the outer peripheral surface of the shaft member from the second When the surface area passes through the first hydrodynamic pressure holding area toward the first surface area, it can flow from the fourth surface area to the second hydrodynamic pressure holding area on the second load-carrying area as the outer ring portion rotates. Fluid to generate dynamic pressure.

In addition, another object of the above-mentioned object is achieved by a hydrodynamic bearing in which the outer peripheral surface of the shaft member is on the opposite side of the first surface area and the second surface area with respect to the axis of the shaft member, respectively Including the third surface area and the fourth surface area.

Also, another purpose of the above purpose is to use a fluid The pressure bearing is achieved by making the outer diameter of the outer peripheral surface of the shaft member larger than the outer diameter of the insertion portion of the shaft member.

In addition, another purpose of the above-mentioned purpose is achieved by a hydrodynamic bearing, which can be a cam follower or a roller follower.

Furthermore, another purpose of the above-mentioned object is achieved by a cam mechanism having a rotatable cam with a spiral cam rib and a rotating member that can rotate with the rotation of the cam, the rotating member having There are a plurality of the above-mentioned fluid dynamic pressure bearings, and they are formed to rotate the rotating member by contacting at least one of the plurality of fluid dynamic pressure bearings with a cam rib.

Moreover, another purpose of the above-mentioned object is achieved by a cam mechanism, which is to fix the shaft member of each of a plurality of fluid dynamic pressure bearings on a rotating member such that the cam ribs contact the plurality of fluid dynamic pressure bearings. In each case, the first fluid dynamic pressure holding area of each of the plurality of fluid dynamic pressure bearings faces the cam rib.

Furthermore, another purpose of the above-mentioned object is achieved by a cam mechanism provided with a rotatable planar cam and a member that can move with the rotation of the planar cam, and the member is provided with the aforementioned fluid at its tip The dynamic pressure bearing is formed to move the member by contacting the planar cam with the fluid dynamic pressure bearing.

Moreover, another purpose of the above-mentioned object is achieved by a cam mechanism, which is to fix the shaft member of the fluid dynamic pressure bearing on the member such that when the planar cam contacts the fluid dynamic pressure bearing, the fluid dynamic pressure bearing The first fluid dynamic pressure holding area faces the planar cam.

As mentioned above, by forming a dynamic pressure groove on the first surface area of the outer peripheral surface of the shaft member, the dynamic pressure caused by the fluid is generated in the first load load area in the radial gap, thereby reducing the shaft The friction between the member and the outer ring portion has the following effects: a bearing that can reduce torque, has high rotation accuracy, and can be used without obstacles under heavy loads can be realized. In addition, by forming the dynamic pressure groove on the second surface area of the outer peripheral surface of the shaft member, the following effect can be achieved: whether the outer ring portion rotates forward or backward with respect to the shaft member, All of them are made to generate dynamic pressure caused by the fluid in the first load load region in the radial gap, thereby reducing the friction between the shaft member and the outer ring portion. In addition, by making the dynamic pressure groove into a substantially V-shape, the following effects can be exerted: it can make it more efficient to produce vivid pressure. In addition, by forming pits and arc grooves, the following effects can be exerted: it can make it more efficient and lively press.

In addition, by using the fluid dynamic pressure bearing of the present invention in the cam mechanism, the following effects can be achieved: a high rotation accuracy and load capacity can be achieved, which is suitable for a long service life, and because the fluid of the present invention There are no rollers in the dynamic pressure bearing and the cam mechanism improves the quietness.

Furthermore, other purposes, features and advantages of this aspect should be clear from the following description of the embodiments of the present invention with additional drawings.

101, 101a, 101b, 101c ‧ ‧ fluid dynamic pressure bearing

102‧‧‧Outer Wheel Department

103‧‧‧Radial clearance

104‧‧‧Shaft member

104a‧‧‧Axis

105‧‧‧Insertion part

106‧‧‧Fixed member receiving hole

107‧‧‧Outer peripheral surface of shaft member

108‧‧‧The first dynamic pressure generating area for forward rotation (the first surface area)

109‧‧‧The first reversal dynamic pressure generating area (the second surface area)

110‧‧‧The first fluid dynamic pressure holding area

111‧‧‧Dynamic pressure groove

112‧‧‧Vertex of dynamic pressure groove

113‧‧‧Pit

114‧‧‧Arc groove

115‧‧‧The second dynamic pressure generating area for forward rotation (the third surface area)

116‧‧‧Second reversal dynamic pressure generating area (4th surface area)

117‧‧‧Second fluid power holding area

118‧‧‧Oil hole

119‧‧‧Outer circumference of outer wheel

120‧‧‧Inner peripheral surface of outer wheel

121‧‧‧The first load area

122‧‧‧Second load area

201‧‧‧Cam mechanism

202‧‧‧Cam

203‧‧‧Cam axis

204‧‧‧Cam Rib

205‧‧‧The first cam surface

206‧‧‧Second cam surface

207‧‧‧Rotating member

208‧‧‧Rotating member axis

301‧‧‧Cam mechanism

302‧‧‧Plane Cam

303‧‧‧Plane cam axis

304‧‧‧Component

α‧‧‧Angle

Fig. 1 is a cross-sectional view of the fluid dynamic pressure bearing of the present invention as seen from the side.

Fig. 2 is a schematic view of the first embodiment seen from the side surface of one side of the shaft member.

Fig. 3 is a schematic view of the second embodiment seen from the side surface of one side of the shaft member.

Fig. 4 is a schematic view of the third embodiment seen from the side surface of one side of the shaft member.

Fig. 5 is a schematic view of the fourth embodiment seen from the side surface of one side of the shaft member.

Fig. 6 is a schematic view of the fifth embodiment seen from the side surface of one side of the shaft member.

Fig. 7 is a schematic view of the sixth embodiment seen from the side surface of one side of the shaft member.

Fig. 8 is a schematic view of the seventh embodiment seen from the side surface of one side of the shaft member.

Fig. 9 is a schematic view of the eighth embodiment seen from the side surface of one side of the shaft member.

Fig. 10 is a schematic view of the ninth embodiment seen from the side surface of one side of the shaft member.

Fig. 11 is a schematic view of the tenth embodiment seen from the side surface of one side of the shaft member.

Fig. 12 is a schematic view of the eleventh embodiment seen from the side surface of one side of the shaft member.

Fig. 13 is a schematic view of the first embodiment seen from the opposite side surface of the shaft member.

Fig. 14 is a schematic view of the second embodiment seen from the opposite side surface 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.

Fig. 17 is a schematic view seen from the front of a cam mechanism using the fluid dynamic pressure bearing of the present invention.

Fig. 18 is a schematic cross-sectional view of the contact between the fluid dynamic pressure bearing of the present invention and the cam surface viewed from below.

Fig. 19 is a schematic view seen from the front of another cam mechanism using the fluid dynamic pressure bearing of the present invention.

The form used to implement the invention

The embodiments of the present invention are described below with reference to the drawings, but the present invention is not limited by these embodiments.

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

FIG. 1 shows a cross-sectional view of the hydrodynamic bearing 101. The fluid dynamic pressure bearing 101 includes a shaft member 104 and an outer ring portion 102 rotatable along the outer peripheral surface 107 of the shaft member 104. Between the outer peripheral surface 107 of the shaft member 104 and the inner peripheral surface 120 of the outer ring portion 102 is provided Radial gap 103. In FIG. 1, the fluid dynamic pressure bearing 101 is additionally provided with 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 housing for fixing the shaft member 104 through the insertion portion 105 In the fixing member accommodating hole 106 of fixing members such as bolts of the turret, these insertion portions 105 and fixing members may not be provided. Accommodation hole 106.

FIG. 2 shows a schematic view of the first embodiment of the shaft member 104 of the fluid dynamic pressure bearing 101 of FIG. 1 viewed from the side. The outer peripheral surface 107 of the shaft member 104 includes a first surface area as the first forward rotation dynamic pressure generating area 108, a second surface area as the first reverse dynamic pressure generating area 109, and is arranged on the first forward rotation dynamic pressure generating area 109. The first fluid dynamic pressure holding area 110 between the pressure generating area 108 and the first reversing dynamic pressure generating area 109. In addition, the dotted lines described in Figures 2 to 14 are for the convenience of explaining each area. The first forward rotation dynamic pressure generating region 108 is formed with a dynamic pressure groove 111 recessed with respect to the outer peripheral surface 107 so that the outer ring portion 102 is rotated along the outer peripheral surface 107 of the shaft member 104 from the first positive When the dynamic pressure generating area 108 for turning passes through the first fluid dynamic pressure holding area 110 toward the first dynamic pressure generating area 109 for reverse rotation (forward rotation), it can be located in the first fluid dynamic pressure holding area 110 in the radial gap 103 In the first load load region (see FIG. 18) on the upper side, fluid such as oil flows from the first forward rotation dynamic pressure generating region 108 to the first fluid dynamic pressure holding region 110 following the rotation of the outer ring portion 102 To generate dynamic pressure. In this way, if the dynamic pressure groove 111 is formed in the first forward rotation dynamic pressure generating area 108, fluids such as oil will follow the first forward rotation dynamic pressure generating area in response to the forward rotation of the outer ring portion 102. The dynamic pressure groove 111 of 108 flows toward the first fluid dynamic pressure holding area 110 so as to be collected at the tip portion of the dynamic pressure groove 111, and the collected fluid is blocked at the tip portion, thereby being in the radial gap 103 A membrane composed of a high-pressure fluid is formed on the first load-carrying area located on the first fluid dynamic pressure holding area 110 to generate dynamic pressure caused by the fluid. Due to the dynamic pressure caused by the fluid, the outer ring portion 102 can not contact the shaft member 104 in the first fluid dynamic pressure holding area 110, and has low friction and low torque. Spin.

Alternatively, a dynamic pressure groove 111 recessed with respect to the outer peripheral surface 107 may be formed in the first reversal dynamic pressure generating region 109 so that the outer ring portion 102 is rotated along the outer peripheral surface 107 of the shaft member 104 from When the first dynamic pressure generating area 109 for reverse rotation passes through the first fluid dynamic pressure holding area 110 to the first dynamic pressure generating area 108 for forward rotation (reverse rotation), the first fluid dynamic pressure can be located in the radial gap 103 In the first load area (see FIG. 18) on the holding area 110, the flow from the first reversal dynamic pressure generating area 109 to the first fluid dynamic pressure holding area 110 follows the rotation of the outer ring portion 102 Fluids such as oil to generate dynamic pressure. In this way, if the dynamic pressure groove 111 is formed in the first reversal dynamic pressure generating area 109, in response to the reversal of the outer ring portion 102, fluid such as oil will follow the first reversing dynamic pressure generating area The dynamic pressure groove 111 of 109 flows toward the first fluid dynamic pressure holding area 110 so as to be collected at the tip portion of the dynamic pressure groove 111, and the collected fluid is blocked at the tip portion, thereby being in the radial gap 103 A film composed of a high-pressure fluid is formed on the first load-carrying area on the first fluid dynamic pressure holding area 110 to generate dynamic pressure caused by the fluid. Due to the dynamic pressure caused by 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 area 110.

The dynamic pressure groove 111 as the first surface area of the first forward rotation dynamic pressure generating area 108 may be formed by a plurality of grooves having a substantially V-shape, and may also be formed such that the apex portion of the substantially V-shape Opposite the first dynamic pressure generating region 109 for reverse rotation. In addition, the dynamic pressure groove 111 as the second surface area of the first reversal dynamic pressure generating area 109 may have a plurality of substantially V-shaped grooves. The groove is formed in a rectangular shape, and it may be formed so that the apex portion of the substantially V-shape faces the first dynamic pressure generating region 108 for forward rotation. By making the dynamic pressure groove 111 into a substantially V-shaped groove, the fluid flows to the apex 112 of the substantially V-shaped tip portion, and the collected fluid is blocked at the apex 112, As a result, a film composed of a high-pressure fluid is formed on the first load-bearing region located on the first fluid dynamic pressure holding region 110 in the radial gap 103, and a dynamic pressure caused by the fluid is generated.

In addition, the substantially V-shaped vertex 112 of the dynamic pressure groove 111 of the first forward rotation dynamic pressure generating area 108 and the substantially V-shaped apex portion 112 of the first dynamic pressure generating area 109 for reverse rotation The apex portions 112 of the V-shape are formed to face each other, so that the outer ring portion 102 can be located on the first load bearing area on the first fluid dynamic pressure holding area 110 in the radial gap 103 regardless of forward or reverse rotation. A membrane made of high-pressure fluid is formed.

As shown in FIG. 3, on the outer peripheral surface 107 of the shaft member 104, one or more arc grooves 114 may be formed along the circumferential direction of the outer peripheral surface 107. In addition, the arc groove 114 may be formed to connect the substantially V-shaped apex portion 112 of the tip portion of the dynamic pressure groove 111. When formed in this manner, the first forward rotation dynamic pressure generating area 108 and the first reverse rotation In the dynamic pressure groove 111 of the dynamic pressure generating area 109, grooves in the shape of herringbone facing each other are formed. By forming the arc groove 114 on the outer peripheral surface 107 of the shaft member 104, the fluid can be collected more efficiently, and a film composed of a high-pressure fluid can be formed on the first load-bearing area, resulting in the generation of fluid Dynamic Pressure.

As shown in FIG. 4, on the outer peripheral surface 107 of the shaft member 104, the first dynamic pressure generating area 108 for forward rotation and the first dynamic pressure generating area 109 for reverse rotation In the first fluid dynamic pressure holding region 110 between, a plurality of recessed pits 113 may be formed. The outer diameter of the pit 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 area 110, the plurality of dimples 113 can be used for the first forward rotation when the outer ring portion 102 rotates forward or backward with respect to the shaft member 104 The dynamic pressure generating area 108 or the first reversing dynamic pressure generating area 109 acts on the reservoir of the fluid flowing in the first fluid dynamic pressure maintaining area 110 to increase the film forming ability of the fluid. Therefore, it is possible to form a film composed of a fluid with a higher pressure in the first load-bearing region located on the first fluid dynamic pressure holding region 110 in the radial gap 103 to generate dynamic pressure by the fluid. Due to the dynamic pressure caused by 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 area 110. Furthermore, as shown in FIG. 4, the pit 113 may be formed in the first forward rotation dynamic pressure generating area 108 and the first reverse dynamic pressure generating area 109, or may be formed on the outer peripheral surface 107 of the shaft member 104. Overall.

The fourth to ninth embodiments are shown in Figs. 5-10. FIG. 5 is an embodiment in which pits 113 are formed in the embodiment in FIG. 3, and FIG. 6 is an embodiment in which the number of formed dynamic pressure grooves 111 and arc grooves is increased in the embodiment in FIG. 3, and FIG. 7 It is an embodiment in which pits 113 are formed for the embodiment of FIG. 6, FIG. 8 is an embodiment in which the arc groove 114 of the embodiment of FIG. 6 is formed into a ring shape, and FIG. 9 is an embodiment of the embodiment of FIG. 8. An example of the pit 113 is shown, and FIG. 10 is an example showing another shape of the dynamic pressure groove. In this way, dynamic pressure can be generated by combining all shapes of dynamic pressure grooves, arc grooves, and pits, and it can be selected according to the size of the load torque and the environment where the fluid dynamic pressure bearing is used. Various shapes. Furthermore, the shapes of the dynamic pressure grooves, arc grooves, and pits formed on the outer peripheral portion 107 are not limited by these embodiments.

In FIGS. 2 to 10, although the dynamic pressure groove 111 of the first forward rotation dynamic pressure generating region 108 and the dynamic pressure groove 111 of the first reverse dynamic pressure generating region 109 are relative to the shaft member 104 shown in FIG. The axis 104a is formed in a symmetrical shape, but as shown in Figures 11 and 12, the first forward rotation dynamic pressure generating region 108, the first reverse dynamic pressure generating region 109, and the first fluid dynamic pressure The holding area 110 is included on the outer peripheral surface 107 of the shaft member 104 in a form having an angle α with respect to the axis 104 a of the shaft member 104. In addition, the pits 113 may be formed to be distributed to have an angle α with respect to the axis 104a. Furthermore, the angle α can be determined so that when the fluid dynamic pressure bearing 101 is used in the cam mechanism as described later, the dynamic pressure caused by the fluid can be generated at the most pressed part of the outer ring portion 102 of the fluid dynamic pressure bearing 101 on. By having the angle α like this, the following effect can be exerted: the friction between the shaft member 104 and the outer ring portion 102 can be reduced in accordance with the cam mechanism using the fluid dynamic pressure bearing 101.

As shown in FIGS. 13 and 14, the outer peripheral surface 107 of the shaft member 104 may further include a second forward rotation dynamic pressure generating area 115 as a third surface area, and a second reverse dynamic pressure generating area as a fourth surface area. The generating area 116 and the second fluid dynamic pressure holding area 117 are arranged between the second dynamic pressure generating area 115 for forward rotation and the second dynamic pressure generating area 115 for reverse rotation. It is also possible to form a dynamic pressure groove 111 recessed with respect to the outer circumferential surface 107 in the second forward rotation dynamic pressure generating region 115, so that the outer ring portion 102 is rotated along the outer circumferential surface 107 of the shaft member 104 from the second When the dynamic pressure generating area 115 for forward rotation passes through the second fluid dynamic pressure holding area 117 toward the second dynamic pressure generating area 116 for reverse rotation, that is, it rotates along When the outer peripheral surface 107 of the shaft member 104 moves from the first forward rotation dynamic pressure generating area 108 through the first fluid dynamic pressure holding area 110 to the first reverse dynamic pressure generating area 109 (forward rotation), the gap 103 In the second load area (see FIG. 18) located on the second fluid dynamic pressure holding area 117, the outer ring portion 102 rotates and flows from the second forward rotation dynamic pressure generating area 115 to the second 2 Fluid dynamic pressure maintains fluid such as oil in the area 117 to generate dynamic pressure. Alternatively, a dynamic pressure groove 111 recessed with respect to the outer peripheral surface 107 may be formed in the second reverse dynamic pressure generating region 116 so that the outer ring portion 102 is rotated along the outer peripheral surface 107 of the shaft member 104 from When the second dynamic pressure generating area 116 for reverse rotation passes through the second fluid dynamic pressure holding area 117 toward the second dynamic pressure generating area 115 for forward rotation, that is, it rotates along the outer peripheral surface 107 of the shaft member 104 from the first reverse When the dynamic pressure generating area 109 for turning passes through the first fluid dynamic pressure holding area 110 to the first dynamic pressure generating area 108 for forward rotation (reverse), it can be located in the second fluid dynamic pressure holding area 117 in the radial gap 103 In the second load area (see FIG. 18) on the upper side, fluid such as oil flows from the second reversal dynamic pressure generating area 116 to the second fluid dynamic pressure holding area 117 following the rotation of the outer ring portion 102 To generate dynamic pressure. In this way, when the dynamic pressure groove 111 is formed on the second dynamic pressure generating area 115 for forward rotation and the dynamic pressure groove 111 is formed on the second dynamic pressure generating area 116 for reverse rotation, the outer ring portion 102 In the forward or reverse rotation, the fluid flows along the second dynamic pressure generating area 115 for forward rotation or the dynamic pressure groove 111 of the second reverse dynamic pressure generating area 116 toward the second fluid dynamic pressure maintaining area 117 to be collected At the tip portion of the dynamic pressure groove 111, the collected fluid is blocked at the tip portion, whereby the second fluid located at a position different from the first fluid dynamic pressure holding area 110 in the radial gap 103 The second load on the dynamic pressure holding area 117 On the load area (refer to Figure 18), a membrane composed of high-pressure fluid is also formed, and dynamic pressure caused by the fluid is generated. Due to the dynamic pressure caused by the fluid, the outer ring portion 102 can also rotate with low friction and low torque without contacting the shaft member 104 in the second fluid dynamic pressure holding region 117.

Furthermore, the second dynamic pressure generating region 115 for forward rotation may be arranged on the opposite side of the first dynamic pressure generating region 108 for forward rotation with respect to the axis 104a of the shaft member 104 shown in FIG. 1. In addition, the second dynamic pressure generating region 116 for reverse rotation may be arranged on the opposite side of the first dynamic pressure generating region 109 for reverse rotation with respect to the axis 104a of the shaft member 104 shown in FIG. 1.

Furthermore, 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 made 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, the outer peripheral surface 107 can be used as a stopper when fitting the fluid dynamic pressure bearing 101 to a rotating member such as a turret of a cam mechanism. As for squeezing too much into the rotating member, thereby ensuring the length of the outer peripheral surface 107 relative to the axis 104a of the shaft member 104, and forming the outer ring portion 102 to smoothly rotate along the outer peripheral surface 107 of the shaft member 104.

As shown in FIGS. 15 and 16, the outer ring portion 102 may be provided with an oil passage hole 118 that passes 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 smoothly flow out from the outer circumferential surface 119 of the outer ring portion 102 and the radial gap 103 between the outer circumferential surface 107 of the shaft member 104 and the inner circumferential surface 120 of the outer ring portion 102 Inflow.

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

The cam mechanism 201 using the fluid dynamic pressure bearing 101 is shown in FIGS. 17 and 18. As shown in FIG. 17, the cam mechanism 201 is provided with a cam 202 that has a spiral cam rib 204 on all or part of the camshaft that can rotate about the cam axis 203, and a cam 202 that can rotate with the rotation of the cam 202 The rotating member axis 208 is a rotating member 207 such as a turret rotating at the center. Furthermore, although Figure 17 shows a reduction mechanism using a roller gear (spherical) cam as the cam mechanism, it can also be an indexing mechanism using a roller gear cam, using a cylindrical cam or a barrel Cam deceleration mechanism or indexing mechanism, or other cam mechanisms such as flat cams or flat cams using flat cams or groove cams, or other cam mechanisms. The rotating member 207 is provided with a plurality of fluid dynamic pressure bearings 101 along its outer circumferential direction. The method of mounting the hydrodynamic bearing 101 to the rotating member 207 of the cam mechanism 201 includes, for example, inserting the hydrodynamic bearing 101 into the rotating member 207 through the insertion portion 105 of the shaft member 104, and inserting a fixing member such as a bolt into the fixing member accommodating hole 106. The method of fixing the shaft member 104 to the rotating member 207 by fastening 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 insertion portion 105 provided on the rotating member 207 The method of inserting the inner threaded screw into the fixing screw to fix the shaft member 104 to the rotating member 207 (at this time, the insertion portion 105 may also be provided with a flat-bottomed cavity, a V-shaped cavity, etc.); by The insert 105 of the fluid dynamic pressure bearing 101 is press-fitted (tightly fitted) against the rotating member 207 and fitted to fix it; the insert 105 of the fluid dynamic pressure bearing 101 faces the rotating member 207 for clearance fit, and the gap The method of introducing a screw stopper to fix it, etc., and various other methods that are not limited to these methods. When the cam 202 rotates, although the first protrusion of the cam rib 204 The contact between the wheel surface 205 or the second cam surface 206 and the outer circumferential surface 119 of the outer ring portion 102 of the hydrodynamic bearing 101 presses the outer circumferential surface 119 of the hydrodynamic bearing 101, and the rotating member 207 rotates. The outer ring portion 102 of the fluid dynamic pressure bearing 101 is supported by the shaft member 104 and is rotatable, so it will make rolling contact with the cam rib 204.

18 is a cross-sectional outline showing the contact state of 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, 206 of the cam rib 204 at a certain point in time of the cam mechanism Figure. When the cam rib 204 rotates in the direction of the arrow along with the rotation of the cam 202, the outer ring portion 102 of the fluid dynamic pressure bearing 101a, 101c rolling in contact with the cam 202 will move in the direction of the arrow (clockwise) with respect to the shaft member 104. Direction or counterclockwise), and as the outer ring portion 102 rotates, the fluid in the radial gap will also rotate.

In more detail, by the contact of the first cam surface 205 of the cam rib 204 with the outer ring portion 102 of the fluid dynamic pressure bearing 101a, the outer ring portion 102 is pressed, and the center axis of the outer ring portion 102 is opposed to the shaft member When the central axis of 104 is eccentric, the outer ring portion 102 is supported by the shaft member 104 and rotates clockwise from the first forward rotation dynamic pressure generating area 108 through the first fluid dynamic pressure holding area 110 to the first reverse The dynamic pressure generation area 109 is switched to. The fluid in the radial gap 103 also flows from the first forward rotation dynamic pressure generating region 108 to the first fluid dynamic pressure maintaining region 110 as the outer ring portion 102 rotates. Here, by pressing from the first cam surface 205 to the outer ring portion 102, the portion receiving the load on the outer peripheral surface 107 of the shaft member 104 is limited to the portion facing the first cam surface 205. Therefore, on the outer peripheral surface of the shaft member 104 facing the first cam surface 205 On the part 107, it is necessary to form a film composed of a high-pressure fluid to generate dynamic pressure caused by the fluid to reduce the friction between the shaft member 104 and the outer ring portion 102. Here, it is only necessary to fix the shaft member 104 on the rotating member 207 so that the first dynamic pressure generating region 108 for forward rotation and the first dynamic pressure generating region 109 for reverse rotation included in the outer peripheral surface 107 are arranged. 1 The fluid dynamic pressure holding area 110 faces the first cam surface 205, so that the first load bearing area 121 located on the first fluid dynamic pressure holding area 110 in the radial gap 103 can generate fluid-induced dynamics. Therefore, the friction between the shaft member 104 and the outer ring portion 102 can be reduced. Moreover, even if the cam 202 is reversed, the outer ring portion 102 is supported by the shaft member 104 and rotated counterclockwise so as to move from the first reversal dynamic pressure generating area 109 to the first fluid dynamic pressure holding area 110 through the first fluid dynamic pressure holding area 110. In the case of the dynamic pressure generating region 108 for normal rotation, the dynamic pressure caused by the fluid may be generated in the first load-carrying region 121 in the same manner.

As shown in Figures 17 and 18, it can also be made that the fluid dynamic pressure bearing 101b does not contact 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. Cam ribs 204.

The fluid dynamic pressure bearing 101c is in contact with the second cam surface 206 on the opposite side to the first cam surface 205, that is, the cam surface contacting and corroded by the fluid dynamic bearing 101a is the cam surface on the opposite side. Here, as with the fluid dynamic pressure bearing 101a, by pressing from the second cam surface 206 toward the outer ring portion 102, the portion receiving the load on the outer peripheral surface 107 of the shaft member 104 is limited to the portion facing the second cam surface 206 section. Therefore, in order to form the portion of the outer peripheral surface 107 of the shaft member 104 facing the second cam surface 206 to be composed of a high-pressure fluid To generate dynamic pressure caused by the fluid, the outer peripheral surface 107 can also be made to further include a second forward rotation dynamic pressure generating region 115, a second reverse dynamic pressure generating region 116, and a second forward rotation The second fluid dynamic pressure holding area 117 between the dynamic pressure generating area 115 and the second reversing dynamic pressure generating area 116. Moreover, it is only necessary to fix the shaft member 104 to the rotating member 207 so that the second dynamic pressure generating region 115 for forward rotation and the second dynamic pressure generating region 116 for reverse rotation included in the outer peripheral surface 107 are arranged. If the fluid dynamic pressure holding area 117 faces the second cam surface 206, the outer ring portion 102 is supported by the shaft member 104 and rotates counterclockwise to pass through the second fluid dynamic pressure generation area 116 from the second reversal dynamic pressure generating area 116. When the holding area 117 faces the second dynamic pressure generating area for forward rotation 115, the cam 202 is still reversed, and the outer ring portion 102 is supported by the shaft member 104 and rotates clockwise from the second dynamic pressure generating area for forward rotation 115. When passing through the second fluid dynamic pressure holding area 117 toward the second reversing dynamic pressure generating area 116, it can be on the second load area 122 located on the second fluid dynamic pressure holding area 117 in the radial gap 103 , So that it generates dynamic pressure caused by the fluid, and can reduce the friction between the shaft member 104 and the outer ring portion 102.

Another cam mechanism 301 using the fluid dynamic pressure bearing 101 is shown in FIG. 19. As shown in FIG. 19, the cam mechanism 301 includes a planar cam 302 that can rotate about the planar cam axis 303 and a member 304 that can move with the rotation of the planar cam 302. The flat cam 302 may also be a flat cam, a groove cam, or the like. The member 304 has a fluid dynamic pressure bearing 101 at its tip. By making the planar cam 302 contact the fluid dynamic pressure bearing 101, the member 304 is formed to move. For example, as in Fig. 19, when the plane cam 302 rotates around the plane cam axis 303, the front end of the member 304 The hydrodynamic bearing 101 will contact the end or groove of the planar cam 302, and following the contact formed by its rotation, the member 304 will move straight up and down. When the planar cam 302 contacts the fluid dynamic pressure bearing 101, 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 front end of the member 304.

In addition, when the planar cam 302 is in contact with the fluid dynamic pressure bearing 101, by pressing the outer ring portion 102 from the planar cam 302, the portion receiving the load on the outer peripheral surface 107 of the shaft member 104 is the end facing the planar cam 302 and the groove part. Therefore, the shaft member 104 of the fluid dynamic pressure bearing 101 can also be fixed to the member 304 so that when the planar cam 302 is in contact with the fluid dynamic pressure bearing 101, it is arranged on the first positive side included in the outer peripheral surface 107 of the shaft member 104. The first fluid dynamic pressure holding area 110 between the turning dynamic pressure generating area 108 and the first reversing dynamic pressure generating area 109 faces the end of the planar cam 302 and the groove. By fixing the shaft member 104 in this way, it is possible to generate the dynamic pressure caused by the fluid in the first load-bearing area located on the first fluid dynamic pressure holding area 110 in the radial gap 103, thereby reducing The friction between the shaft member 104 and the outer ring portion 102.

Although the above description is made for specific embodiments, the present invention is not limited by them. Various changes and modifications can be made within the scope of the principle of the present invention and the scope of the accompanying patent application, which is essential to the present invention. It is very clear to those with ordinary knowledge in the technical field.

104: Shaft member

105: Insertion part

107: Outer peripheral surface of shaft member

108: The first dynamic pressure generating area for forward rotation (the first surface area)

109: The first reversal dynamic pressure generating area (the second surface area)

110: The first fluid dynamic pressure holding area

111: Dynamic pressure groove

112: Dynamic pressure groove apex

Claims (15)

A fluid dynamic pressure bearing used in a cam mechanism provided with a rotatable cam having a cam rib and a rotatable rotating member, or used in a cam mechanism provided with a rotatable flat cam and a movable member, the aforementioned The fluid dynamic pressure bearing is characterized in that the fluid dynamic pressure bearing is provided with a shaft member and an outer ring portion rotatable along the outer circumferential surface of the shaft member. The outer circumferential surface of the shaft member and the inner circumferential surface of the outer ring portion A radial gap is provided therebetween, and the outer peripheral surface of the shaft member includes a first surface area, a second surface area, and a first hydrodynamic pressure holding area arranged between the first surface area and the second surface area, In addition, a dynamic pressure groove is formed in the first surface area to rotate the outer ring portion along the outer peripheral surface of the shaft member from the first surface area through the first fluid dynamic pressure holding area toward the first In the case of two surface areas, it is possible to flow from the first surface area to the first load bearing area located on the first fluid dynamic pressure holding area in the radial gap as the outer ring portion rotates. The fluid in the first fluid dynamic pressure holding area causes dynamic pressure to be generated. When the rotatable rotating member is provided with the fluid dynamic pressure bearing, the shaft member is fixed to the rotatable rotating member such that: on the cam rib When contacting the fluid dynamic pressure bearing, the first fluid dynamic pressure holding area faces the cam ribs, and when the movable member is provided with the fluid dynamic pressure bearing, the front The shaft member is fixed to the movable member such that when the planar cam contacts the fluid dynamic pressure bearing, the first fluid dynamic pressure holding area faces the planar cam. The fluid dynamic pressure bearing of claim 1, wherein a dynamic pressure groove is formed in the second surface area so that the outer ring portion is rotated along the outer peripheral surface of the shaft member and passes through the second surface area When the first fluid dynamic pressure holding area faces the first surface area, the first load-carrying area can flow from the second surface area to the first fluid dynamic pressure as the outer ring portion rotates. Keep the fluid in the area to generate dynamic pressure. The fluid dynamic pressure bearing of claim 1, wherein the dynamic pressure grooves in the first surface area are formed by a plurality of grooves having a substantially V shape, and are formed such that the apex of the substantially V shape and the first 2 surface areas face each other. The fluid dynamic pressure bearing of claim 2, wherein the dynamic pressure grooves in the second surface area are formed by a plurality of grooves having a substantially V shape, and are formed such that the apex portion of the substantially V shape and the first 1 surface areas face each other. The fluid dynamic pressure bearing of claim 1, wherein in the first fluid dynamic pressure holding area, a plurality of recesses are formed on the outer peripheral surface of the shaft member. The fluid dynamic pressure bearing of claim 1, wherein a circular arc groove is formed along the circumferential direction of the outer peripheral surface of the aforementioned shaft member. The fluid dynamic pressure bearing according to claim 1, wherein the outer ring portion is provided with an oil passage hole that opens from the outer circumferential surface to the inner circumferential surface. The fluid dynamic pressure bearing according to any one of claims 2 to 7, wherein the outer peripheral surface of the shaft member further includes a third surface area, a fourth surface area, and one of the third surface area and the fourth surface area The second fluid dynamic pressure holding area is formed between the second fluid dynamic pressure holding area, and the third surface area is formed with a dynamic pressure groove, so that the outer ring portion is rotated along the outer peripheral surface of the shaft member and passes through the first surface area. When the first fluid dynamic pressure holding area faces the second surface area, the second load-bearing area located on the second fluid dynamic pressure holding area in the radial gap can be provided by following the outer ring portion The fluid flowing from the third surface area to the second fluid dynamic pressure holding area is rotated to generate dynamic pressure, and a dynamic pressure groove is formed in the fourth surface area to rotate the outer ring portion When it is formed along the outer peripheral surface of the shaft member from the second surface area through the first fluid dynamic pressure holding area toward the first surface area, the second load-bearing area can be placed on the second load bearing area by following the outer ring portion The fluid rotating and flowing from the fourth surface area to the second fluid dynamic pressure holding area generates dynamic pressure. The fluid dynamic pressure bearing of claim 8, wherein the outer peripheral surface of the shaft member is on the opposite side of the first surface area and the second surface area with respect to the axis of the shaft member, and each includes the third surface area and The aforementioned fourth surface area. The fluid dynamic pressure bearing 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. Such as the fluid dynamic pressure bearing of claim 1, which is a cam follower or roller from Moving parts. A cam mechanism is provided with a rotatable cam having a cam rib and a rotatable rotating member. The cam mechanism is characterized in that the rotating member is provided with a plurality of fluid dynamic pressure bearings of claim 1, and is formed by the aforementioned The cam rib contacts at least one of the plurality of fluid dynamic pressure bearings to rotate the rotating member and the cam. The cam mechanism of claim 12, wherein the shaft member of each of the plurality of fluid dynamic pressure bearings is fixed to the rotation member such that when the cam rib contacts each of the plurality of fluid dynamic pressure bearings, The first fluid dynamic pressure holding area of each of the plurality of fluid dynamic pressure bearings faces the cam rib. A cam mechanism is provided with a rotatable planar cam and a movable member. The cam mechanism is characterized in that the member is provided with a fluid dynamic pressure bearing of claim 1 at the front end thereof, and is formed to contact the fluid by the planar cam The dynamic pressure bearing causes the aforementioned member to move and the aforementioned flat cam to rotate. The cam mechanism of claim 14, wherein the shaft member of the fluid dynamic pressure bearing is fixed to the member such that when the planar cam contacts the fluid dynamic pressure bearing, the first fluid of the fluid dynamic pressure bearing The dynamic pressure holding area faces the aforementioned planar cam.

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