Ntn Corporation

Bridgestone Corporation

Kabushiki Kaisha Bridgestone

Keisuke Sone

Kazuhiko Hozumi

Koji Sahashi

Masahiro Ozawa

Hiroshi Isobe

Kazuhiko Yoshida

Hirokazu Ooba

Hiroyuki Yamada

Akira Torii

Eiji Tajima

Hisashi Ohtsuki

Tatsuro Sugiyama

Yoshihisa Kaneko

Mitsuru Umekida

Masayuki Kuroda

Nobuyoshi Yamashita

Motoharu Niki

Masuo Takaki

Yutaka Yamauchi

Syougo Suzuki

Takashi Nozaki

Akira Wakita

Hiroyuki Hakamata

Kiyohiro Itou

Takeshi Ikeda

Yasuhiro Suzuki

Tomomi Ishikawa

Shigeaki Fukushima

Yukihiro Nishio

Mika Kohara

Hiroyuki Ogura

Katsumi Tashiro

Arito Matsui

Yutaka Tanigaki

Masafumi Nakakoji

Yoshihiko Hayama

Hiroki Mukai

Ikuya Tateoka

Tomohide Mizoguchi

Shogo Okada

A link actuator includes a proximal end side link hub, a distal end side link hub, and link mechanisms which connect the distal end side link hub to the proximal end side link hub. Each of the link mechanisms includes a proximal side end link member, a distal side end link member, and an intermediate link member. Each of the proximal end side link hub and the distal end side link hub is provided with a through-hole which allows an origin positioning shaft to be inserted therethrough. The distal end posture of the link actuator is set to a specified posture by inserting the origin positioning shaft through the through-holes. An amount of operation of actuators in a state where preload is applied to the link actuator is set as a position of an origin of the actuator.

Link actuator to initially set position of origin

The method for initially setting a position of an origin of an actuator includes a first step of setting a distal end posture being a posture of a distal end side link hub relative to a proximal end side link hub of a link actuator to a specified posture; a second step of applying a preload, which is a force that causes the distal end posture to be changed, to the link actuator having the distal end posture being the specified posture; and a third step of storing an amount of operation of each actuator in a state where the preload is applied to the link actuator, wherein the stored amount of operation is set as the position of the origin of the actuator.

Method for initially setting position of origin of link actuators, and link actuator

A parallel link mechanism includes a proximal end side link hub; a distal end side link hub; and three or more link mechanisms that connect the distal end side link hub to the proximal end side link hub in a position-changeable fashion. Each of the link mechanisms has a trinodal structure. Each revolute pair of each of the link mechanisms includes one pair of pair constituent members connected to each other via a bearing. One of the pair constituent members is formed with a shaft portion fitted to an inner periphery of an inner ring of the bearing, and the other of the pair constituent members is formed with an annular inner face forming portion fitted to an outer periphery of an outer ring of the bearing.

Parallel link mechanism, constant velocity universal joint, and link actuator

A link actuating device includes input side and output side link hubs, and two sets of link mechanisms. Each of the link mechanisms is a three-link-chain link mechanism including four revolute pairs, and includes input side and output side end links rotatably connected to the input side and output side link hubs and an intermediate links rotatably connected to input side and output side end links. The link mechanism have a positional relationship in which the revolute pair axes between the link hubs and the end links are located on the same plane and cross each other. At least one of the two sets of link mechanisms is provided with interlocking unit that interlocks the input side end link and the output side end link to each other so as to be rotationally displaced.

Link actuating device

A distal end side link hub is connected to a proximal end side link hub via three or more link mechanisms such that alteration in posture of the distal end side link hub is allowed. Each of the link mechanisms includes a proximal side end link member, a distal side end link member, and an intermediate link member. A line member is disposed between the link hubs, two ends of the line member being held at line member holding points which are on link hub central axes, respectively. In a state where the link hubs are parallel to each other, when the distance from a midpoint to each spherical link center is defined as (D) and the distance from each spherical link center to its corresponding line member holding point is defined as (H), the relationship H=0.5&#xd7;D is established.

Link actuation device

A bearing is interposed in the revolute pair between a proximal end side link hub and each proximal side end link member. A control device controls an actuator, to perform work-time control for causing a determined work operation to be executed and to perform, while the work-time control is stopped, grease circulation control for circulating grease sealed in the bearing. The maximum value &#x3b8;of a bending angle in the work-time control does not exceed the maximum allowable bending angle &#x3b8;'being the maximum value of the bending angle allowable in the mechanism, and the maximum value of the bending angle in the grease circulation control is greater than the maximum value &#x3b8;of the bending angle in the work-time control and smaller than the maximum allowable bending angle &#x3b8;&#x2032;.

A parallel link mechanism includes proximal end side and distal end side link hubs, and three or more link mechanisms. Each link mechanism is a trinodal link mechanism including four revolute pairs, and includes proximal side and distal side end link members and an intermediate link member. In each revolute pair of the link mechanism, a pair of pair constituent members is connected to each other via a bearing. A shaft portion provided in one pair constituent member is fitted on an inner periphery of an inner ring of the bearing, and an annular inner face forming portion provided in the other pair constituent member is fitted on an outer periphery of the outer ring of the bearing. The shaft portion and the annular inner face forming portion define a sealing structure which regulates flow of a lubricant between inside and outside of the bearing.

A fixed type constant velocity universal joint comprises a ball and a lubricating grease sealed therein. A surface roughness of the ball is set to Ra 0.15 &#x3bc;m or less and a surface roughness of a counterpart surface on which the ball rolls is set to be higher than the surface roughness of the ball. An additive composition of the lubricating grease comprises a base oil, a diurea compound, molybdenum dithiocarbamate, zinc dialkyldithiophosphate, melamine cyanurate, molybdenum disulfide, and calcium salt of alkylaromatic sulfonic acid.

Fixed-type constant velocity universal joint

An eight-ball fixed type constant velocity universal joint of an undercut free type is capable of increasing a torque capacity at high operating angles while securing durability at low operating angles. When a distance between a center of a track groove and a center of a ball is denoted by Rt, and when an axial distance between the center of the track groove and a joint center plane is denoted by F, a ratio R1 of F to Rt is set to fall within a range of 0.061&#x2266;R1&#x2266;0.087. When a radial offset amount, which is a distance between the center of the track groove and a joint center axial line is denoted by fr, a ratio R3 of fr to Rt is set to fall within a range of 0.07&#x2266;R3&#x2266;0.19. When an effective cured-layer depth with Hv 513 is denoted by Di and the diameter of the ball is denoted by d, a bottom surface of a track groove of an inner joint member includes a cured layer with an effective cured-layer depth ratio Di/d of at least 0.111 or more.

Fixed type constant velocity universal joint

A fixed type constant velocity universal joint of an eight-ball undercut-free type has improved torque capacity at high operating angle while ensuring durability at low operating angle. Centers of a track groove () of an outer joint member and a track groove () of an inner joint member are respectively separated from a center plane (P) toward axially different sides, and are offset away from a joint center axis (X) to a radially opposite side relative to grooves (). When Rt represents a distance between a center of a ball () and the center of groove (), and F represents an axial distance between plane (P) and the center of groove (), a ratio Rbetween F and Rt is 0.061&#x2266;R&#x2266;0.087. When fr represents a radial offset amount as a distance between axis (X) and the center of groove (), a ratio Rbetween fr and Rt is 0.07&#x2266;R&#x2266;0.19.

Fixed uniform-motion universal joint

A power transmission shaft includes a torque-transmission teeth portion formed on an outer peripheral surface on an end portion side, and a smooth portion formed on the outer peripheral surface adjacent to the torque-transmission teeth portion so as to have a stepwise reduced diameter. A ratio of a minimum diameter of the smooth portion to a minimum diameter of the torque-transmission teeth portion is set to 0.9 or more and 1.02 or less. Further, the torque-transmission teeth portion and the smooth portion undergo heat treatment so as to form a heat-treated hardened layer. The heat-treated hardened layer is formed to increase in depth from a side of the torque transmission teeth portion to a side of the smooth portion. At least a minimum diameter portion of the smooth portion undergoes full hardening.

Power transmission shaft, drive shaft, and propeller shaft

A constant velocity universal joint has high strength and capable of suppressing deformation caused by quenching at an opening end portion of a track groove of an outer joint member. In an undercut-free constant velocity universal joint in which a track groove in a cup portion of the outer joint member has a hardened layer formed by induction quenching, an opening end surface is protruded by a protruding amount t in an axial direction from a groove bottom of the track groove in a relief surface. The protruding amount t satisfies a relation of t=0.037d to 0.185d when a diameter of a torque transmission ball is represented by d. The opening end surface in a protruded portion and an outer surface of the cup portion continuous to the opening end surface have an unhardened layer free from hardening by quenching.

Constant velocity universal joint

In a fixed type constant velocity universal joint, a center of each of guide grooves of an outer joint member is offset to a position of being spaced apart from a joint central plane to a joint opening side by an axial distance, and is spaced apart from a joint central axis line to an opposite side in a radial direction with respect to each of the guide grooves by a radial distance. Further, a center of each of guide grooves of an inner joint member is offset to a position of being spaced apart from the joint central plane to a joint innermost side by the axial distance, and is spaced apart from the joint central axis line to the opposite side in the radial direction with respect to each of the guide grooves by the radial distance.

A fixed constant velocity universal joint with eight balls achieves improvement in cage strength by increasing a smallest outer diameter of a cage and improvement in joint strength at a high operating angle by ensuring required inner spherical area and spherical surface angle in an outer member regardless of the smallest outer diameter of the cage. In the fixed constant velocity joint of the present invention, among eight frontal sections adjacent to an inner spherical surface on an outer member opening side, present between adjacent ball grooves formed on the inner spherical surface, and forming a smallest inner diameter of an outer member opening, any one or any two mutually opposing frontal sections are retracted from the smallest inner diameter in an outward radius direction by a distance required to allow insertion of the cage through the one or two frontal sections (cylindrical surfaces or planar surfaces) in a state in which a cage axial line is perpendicular to an outer member axial line.

Fixed constant-velocity universal joint

In a bearing detachment prevention structure provided in a rotation pair portion of a link mechanism, play filling-up and pre-load adjustment for the bearing are realized with ease. As a means for therefor, there is provided a link actuating device having three or more sets of link mechanisms in each of which end link members are rotatably connected to input and output members respectively arranged on the input and output sides, the respective end link members on the input and output sides being rotatably connected to intermediate link members to form four rotation pair portions, the input and output sides being geometrically the same with respect to a cross section in a central portion of each link mechanism, in which each rotation pair portion of the link mechanisms has a bearing structure consisting of two bearings, with a play filling-up means for regulating axial movement of the two bearings being provided in the rotation pair portions. Further, by appropriately determining the configuration of each component forming the link mechanisms, interference between the components during operation of the link mechanisms is prevented. As a means therefor, a beveled portion is formed on the link side peripheral end edge portion of each input member, whereby interference between the end link member and the outer peripheral surface of the rotation pair portion of each intermediate link member is prevented.

Growing community of inventors

Iwata, Japan

Keisuke Sone