Ntn Corporation

Teruaki Fujio

Tomoshige Kobayashi

Masashi Funahashi

Tohru Nakagawa

Hiroyasu Hirukawa

Manabu Hoshino

Wasaburo Suganuma

Kenta Yamazaki

Tatsuro Sugiyama

Hisaaki Kura

Shin Tomogami

Takeshi Kohara

Kisao Yamazaki

Mika Kohara

Tomoaki Kaneko

Tsubasa Nishikawa

A fixed type constant velocity universal joint has outer joint member track grooves each with a raceway center line that includes an arc-shaped portion having a curvature center that has no offset with respect to a joint center in an axial direction. The track grooves are formed such that adjacent track grooves are inclined in opposite directions. The joint also has inner joint member track grooves that are each mirror-symmetric with a corresponding one of the outer joint member track grooves. When at a maximum operating angle, a torque transmission ball that moves toward an opening side of the outer joint member track groove loses contact with an opening-side end portion of that track groove, and when at an operating angle of 0°, an end portion of a cage projects from the opening-side end portion of the outer joint member in the axial direction.

Fixed type constant velocity universal joint

A fixed type constant velocity universal joint has outer joint member track grooves each with a raceway center line that includes an arc-shaped portion having a curvature center that has no offset with respect to a joint center in an axial direction. The track grooves are formed such that adjacent track grooves are inclined in opposite directions. The joint also has inner joint member track grooves that are each formed to be mirror-symmetric with a corresponding one of the outer joint member track grooves with a plane including the joint center and being orthogonal to the axis of the joint at an operating angle of 0°. When at a large operating angle, an operating angle at which a torque transmission ball loses contact with the inner joint member track groove is larger than that at which the torque transmission ball loses contact with the outer joint member track groove.

A fixed type constant velocity universal joint has an operation mode in which, when a maximum operating angle is taken, in a column portion that is one of column portions on both sides of a pocket of a cage receiving a torque transmission ball at a phase angle and is located on a side corresponding to a phase angle larger than the phase angle, a projection end portion obtained by projecting an end portion of a spherical inner peripheral surface of the outer joint member on the opening side in a perpendicular direction toward the spherical outer peripheral surface of the cage and a projection end portion obtained by projecting an end portion of the spherical outer peripheral surface of the inner joint member on the back side in the perpendicular direction toward the spherical inner peripheral surface of the cage overlap in the axial direction of the cage.

A constant velocity universal joint includes an inner ring and an outer ring. A cage is disposed between an outer spherical surface of the inner ring and an inner spherical surface of the outer ring, and has windows in which respective balls are received. The cage has ball contact surface areas with which the balls come into contact, and includes soft portions that are lower in hardness than the ball contact surface areas. The soft portions are formed by local heat treatment at portions of the windows that are kept out of contact with the balls or surface portions around the windows.

Constant velocity universal joint and cage thereof

Track grooves of an outer joint member include first and second track groove portions. An end portion of the ball raceway center line of each of the first track groove portions is located on the opening side with respect to a joint center and a ball raceway center line of each of the second track groove portions is connected to the end portion. A ball raceway center line of each of the track grooves of the inner joint member is formed to be mirror-image symmetrical with a ball raceway center line of a corresponding one of the paired track grooves of the outer joint member with respect to a plane that includes the joint center at an operating angle of 0&#xb0; and is orthogonal to a joint axial line.

In a fixed type constant velocity universal joint, an axial offset amount of a curvature center of each of track grooves of outer and inner joint members is set to 0. The track grooves of the outer and inner joint members are each inclined with respect to an axis line. The track grooves adjacent to each other in a circumferential direction are inclined in opposite directions. The track grooves of the outer and inner joint members that are opposed to each other are inclined with respect to the axis line in opposite directions. A chamfered portion is formed on a track inlet end of each of the track grooves of the outer joint member. When the cage and the inner joint member are inclined with respect to the outer joint member, balls are incorporated into two cage windows at the same time through the chamfered portions.

Stationary constant-velocity universal joint

In a fixed type constant velocity universal joint according to the present invention, six torque transmitting ball tracks () are defined as a first track, a second track, a third track, a fourth track, a fifth track, and a sixth track along a circumferential direction. Further, in the fixed type constant velocity universal joint according to the present invention, an axial offset amount of a curvature center of each of track grooves () of an outer joint member () and an axial offset amount of a curvature center of each of track grooves () of an inner joint member () are set to 0. Further, in the fixed type constant velocity universal joint according to the present invention, the track grooves () of the outer joint member () and the track grooves () of the inner joint member () are each inclined with respect to an axis line.

Fixed constant velocity universal joint

A fixed type constant velocity universal joint includes an outer joint member having eight curved track grooves, an inner joint member having eight curved track grooves, eight torque transmission balls, and a cage configured to hold the torque transmission balls in pockets. A curvature center of each of the track grooves of the outer joint member and a curvature center of each of the track grooves of the inner joint member are offset from a joint center by an equal distance to opposite sides in the axial direction. The joint has grease sealed therein. Initial pocket gaps between the pockets and the balls each have a positive value. The grease has an initial consistency equivalent to consistency number 1 or 2, and a mixture stability of from 390 to 440.

A fixed type constant velocity universal joint of a track groove crossing type has track grooves of an inner joint member formed so as to be mirror-image symmetrical with the paired track grooves of an outer joint member with respect to a joint center plane at an operating angle of 0&#xb0;. The track grooves of both the joint members each have a length corresponding to a maximum operating angle required for a rear-wheel drive shaft. Further, each axial clearance between the inner joint member and the cage is set larger than an axial clearance formed by a ball track clearance between each of balls and each track groove.

Fixed-type constant velocity universal joint

Six track grooves formed in a spherical inner peripheral surface of an outer joint member are each formed into an arc shape having a curvature center at a joint center. The track grooves are inclined in a circumferential direction of the outer joint member with respect to a joint axial line, and are adjacent to each other in the circumferential direction with their inclination directions opposite to each other. Six track grooves formed in a spherical outer peripheral surface of an inner joint member are formed so as to be mirror-image symmetrical with the track grooves paired therewith of the outer joint member with respect to a joint center plane at an operating angle of 0&#xb0;. An inclination angle of each of the track grooves of the outer joint member with respect to the joint axial line is set to 8&#xb0; or more and 16&#xb0; or less.

A fixed type constant velocity universal joint of a track groove crossing type has track grooves of an inner joint member formed to be mirror-image symmetrical with paired track grooves of an outer joint member with respect to a joint center plane at an operating angle of 0&#xb0;. The track grooves of both the joint members each have a length corresponding to a maximum operating angle (&#x3b8;max) required for a propeller shaft, and surface treatment is performed, for example, on a defined surface of each of the track grooves of the outer joint member so as to reduce frictional resistance (sliding resistance) against balls.

Provided is a fixed type constant velocity universal joint, in which: each of first track groove portions positioned on an interior side of an outer joint member includes an arc part having a curvature center that is positioned without being offset in an axial direction with respect to a joint center; the first track groove portions are inclined in a peripheral direction with respect to a joint axial line (N-N) and adjacent to each other in the peripheral direction with their inclination directions opposite to each other; each of second track groove portions positioned on an opening side is formed into a different shape from a shape of the each of the first track groove portions so as to increase an effective track length at a maximum operating angle; the each of the first track groove portions and the each of the second track groove portions are connected to each other at a position on the opening side with respect to the joint center; each of track grooves of an inner joint member is formed so as to be mirror-image symmetrical with corresponding one of paired track grooves of the outer joint member with respect to a plane including the joint center and being perpendicular to the joint axial line at an operating angle of 0&#xb0;; and an axial clearance between the inner joint member and a cage is set to be larger than an axial clearance corresponding to a clearance between each of balls and each of the track grooves.

A constant velocity universal joint smoothly operates under load and during speed rotation, and also suppresses heat generation and has enhanced durability. An offset in an axial direction between a center of curvature of each of track grooves and a center of curvature of an inner surface of an outer joint member, and an offset in the axial direction between a center of curvature of each of track grooves and a center of curvature of an outer surface of an inner joint member are each set to zero. The track grooves of the outer and inner joint members are each inclined with respect to an axial line. A circumferential length of each of pockets of a cage is set so that two pockets allow balls to be assembled therein at one time under a state in which the two pockets are exposed.

Constant velocity universal joint

A fixed type constant velocity universal joint has track grooves of an outer joint member including first and second track groove portions located on depth and opening sides, respectively. The first track groove portions each have a circular-arc part having a curvature center that is not offset in an axial direction with respect to a joint center, are inclined in a circumferential direction with respect to a joint axial line, and are adjacent to each other in the circumferential direction with their inclination directions opposite to each other. The second track groove portions have a different shape than the first track groove portions to increase an effective track length with respect to a maximum operating angle. The first and second track groove portions are connected respectively to each other on the opening side with respect to the joint center.

A fixed type constant velocity universal joint includes eight or twelve torque transmitting balls arranged in ball tracks formed of pairs of track grooves of an outer joint member and track grooves of an inner joint member, respectively. A center of curvature of each of the track grooves of the outer joint member and a center of curvature of each of the track grooves of the inner joint member have an axial offset of zero. When eight torque transmitting balls are employed, the track grooves of the outer joint member and the inner joint member each include inclined tracks arranged at a 90&#xb0; pitch along a circumferential direction and inclined in opposite directions with respect to an axial line and other tracks which are formed between the inclined tracks and parallel to the axial line.

Growing community of inventors

Iwata, Japan

Teruaki Fujio