Abstract: 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.

Abstract: Provided is a fixed type constant velocity universal joint which can achieve, at low cost, excellent properties in terms of durability, high load condition, low load condition, and high angle condition. The fixed type constant velocity universal joint comprises a lubricating grease sealed therein. A surface roughness of a ball (37) is set to Ra 0.15 ?m or less and a surface roughness of a counterpart surface on which the ball (37) rolls is set to be higher than the surface roughness of the ball (37). 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.

Abstract: Provided is an eight-ball fixed type constant velocity universal joint of an undercut free type, which 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 (32) and a center of a ball (37) is denoted by Rt, and when an axial distance between the center of the track groove (32) and a joint center plane (P) is denoted by F, a ratio R1 of F to Rt is set to fall within a range of 0.061?R1?0.087. When a radial offset amount, which is a distance between the center of the track groove (32) and a joint center axial line (X) is denoted by fr, a ratio R3 of fr to Rt is set to fall within a range of 0.07?R3?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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Provided is a power transmission shaft to achieve enhancement of a static torsional strength of a smooth portion. The power transmission shaft according to the present invention includes a torque-transmission teeth portion (2) formed on an outer peripheral surface on an end portion side, and a smooth portion (3) formed on the outer peripheral surface adjacent to the torque-transmission teeth portion (2) so as to have a stepwise reduced diameter. A ratio of a minimum diameter (D3min) of the smooth portion (3) to a minimum diameter (D2min) of the torque-transmission teeth portion (2) is set to 0.9 or more and 1.02 or less. Further, the torque-transmission teeth portion (2) and the smooth portion (3) undergo heat treatment so as to from a heat-treated hardened layer (4). The heat-treated hardened layer (4) is formed to increase in depth from a side of the torque transmission teeth portion (2) to a side of the smooth portion (3).

Abstract: To achieve both cost reduction and strength enhancement of a cage by appropriately managing, at the time of forming pockets through a punch-pressing process in a base material made of medium-carbon steel, a size of a secondary fracture portion formed in a shear surface of the base material.

Abstract: Provided is a fixed type constant velocity universal joint of an eight-ball undercut-free type, which is capable of achieving an improvement of torque capacity at a high operating angle while ensuring durability at the time of a low operating angle. In the fixed type constant velocity universal joint of the eight-ball undercut-free type, a center of a track groove (32) of an outer joint member and a center of a track groove (35) of an inner joint member are separated from a joint center plane (P) respectively to both sides in an axial direction, and are offset to be positioned away from a joint center axis (X) to a radially opposite side relative to the track grooves (35). When Rt represents a distance between a center of a ball (37) and the center of the track groove (32) of the outer joint member, and F represents an axial distance between the joint center plane (P) and the center of the track groove (32) of the outer joint member, a ratio R1 between F and Rt is set to satisfy 0.061?R1?0.

Abstract: Provided is a constant velocity universal joint having 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 (1d) in a cup portion (1a) of the outer joint member has a hardened layer (8a) formed by induction quenching, an opening end surface (1e) is protruded by a protruding amount t in an axial direction from a groove bottom (c) of the track groove (1d) in a relief surface (1f). The protruding amount t satisfies a relation of t=0.037 d to 0.185 d when a diameter of a torque transmission ball is represented by d. The opening end surface (1e) in a protruded portion (1i) and an outer surface (1j) of the cup portion (1a) continuous to the opening end surface (1e) have an unhardened layer free from hardening by quenching.

Abstract: A shaft coupling includes plates fitted on ends of input and output shafts, respectively. A plurality of guide grooves are formed in the opposed surfaces of the plates, respectively, so that each of the grooves extends perpendicular to the corresponding groove formed in the other plate. A steel ball is disposed between each pair of guide grooves of the plates at a portion where the pair of grooves cross each other. When the steel balls are pushed by the driving plate, they push the driven plate while rolling in the guide grooves, with their movements restricted by a retainer in the radial direction of the plates. Thus, large power can be smoothly transmitted between the rotary members with less frictional resistance. The offset amount can be changed easily. Between the plates, there are only the steel balls and the retainer.

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

Abstract: In a fixed constant velocity universal joint with eight balls, the present invention 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.

Abstract: A rotating side case supporting the rotor of an in-wheel motor and a wheel or a hub are interconnected by a flexible coupling which comprises a motor-side plate and a wheel-side plate having a plurality of grooves and a plurality of grooves formed on their opposed surfaces in the circumferential direction at an angle of 45° from the radial direction of the plates and extending in directions orthogonal to each other, respectively, small balls sandwiched between the grooves and in such a manner that they can slide, and an intermediate plate interposed between the above plates and having guide holes for guiding the small balls in a direction orthogonal to the radial direction of the plates and which has a small number of parts and is easily assembled.

Abstract: A linkage system which offers high rigidity and good assemblability and producibility, and enables parts such as rotary transmission components and actuators to be readily installed. A linkage system includes an input member disposed on an input side, an output member disposed on an output side, and three or more link mechanisms, each link mechanism consisting of end links rotatably coupled to the input member and the output member, respectively, a center link rotatably coupled to the end links on the input side and the output side, and four revolute joints by which the end links are rotatably coupled to the input and output members, and to the center link. The link mechanism being geometrically identical with respect to a center cross-sectional plane relative on the input and output sides. Each of the revolute joints of the link mechanism includes bearings that support at both ends of the revolute joint.

Abstract: A linkage system is provided which is equipped with a compact and high-rigidity link mechanism with a large load capacity. The linkage system includes three or more link mechanisms. Each link mechanism consists of a center link member and end link members rotatably coupled to the center link member and to link hubs that are provided to an input member and an output member, respectively. An input side and an output side of a center cross-sectional plane of each link mechanism are geometrically identical. One or more of revolute joints of two or more of the link mechanisms that are coupled to the input member are provided with a stopping mechanism for stopping the output member at a given position.

Abstract: An object is to provide a shaft coupling which is short in axial dimension, which can transmit large power between shafts even if the offset amount of the shafts is large, and which is less expensive and can be assembled easily. The shaft coupling includes plates 1 and 2 fitted on ends of input and output shafts A and B, respectively. A plurality of guide grooves 5 and 6 are formed in the opposed surfaces of the plates 1 and 2, respectively, so that each of the grooves 5 and 6 extend perpendicular to the corresponding groove formed in the other plate. A steel ball is disposed between each pair of guide grooves 5 and 6 of the plates 1 and 2 at a portion where the pair of grooves 5 and 6 cross each other. When the steel balls are pushed by the driving plate 1, they push the driven plate 2 while rolling in the guide grooves 5 and 6, with their movements restricted by a retainer 4 in the radial direction of the plates.

Abstract: A rotating side case 3b supporting the rotor 3R of an in-wheel motor 3 and a wheel 2 or a hub 4 are interconnected by a flexible coupling 10 which comprises a motor-side plate 11A and a wheel-side plate 11C having a plurality of grooves 11a and a plurality of grooves 11b formed on their opposed surfaces in the circumferential direction at an angle of 45° from the radial direction of the plates and extending in directions orthogonal to each other, respectively, small balls 11m sandwiched between the grooves 11a and 11b in such a manner that they can slide, and an intermediate plate 11B interposed between the above plates 11A and 11C and having guide holes 11s for guiding the small balls in a direction orthogonal to the radial direction of the plates and which has a small number of parts and is easily assembled.

Abstract: A fixed type constant velocity joint includes a cylindrical joint outer ring having an inner spherical surface formed with circumferentially equispaced axially extending track grooves, a joint inner ring having an outer spherical surface formed with circumferentially equispaced axially extending track grooves, balls disposed in ball tracks defined by cooperation between the track grooves in the joint outer and inner rings, and a cage for holding the balls in the ball tracks. The rear open end of the joint outer ring has an inner diameter larger than the outer diameter of the joint inner ring, an inner diameter surface of said cage is a surface having a shape such that the region located forwardly of the axial center is capable of controlling the forward movement of the joint inner ring while the region located rearwardly of the axial center is capable of allowing the axial movement of the joint inner ring.