Jtekt Corporation

Toyoda Koki Kabushiki Kaisha

Nippon Steel Corporation

Yoyoda Koki Kabuhsiki Kaisha

Kazuyuki Ichikawa

Isashi Kashiwagi

Atsushi Ando

Koji Nishi

Minoru Wakamatsu

Yuji Inagaki

Tomonori Ohwaki

Toshiyuki Saito

Tatsuro Ochi

Junji Ando

Tomoo Suzuki

Hiroki Yamato

Hiroyuki Iwashita

Yosei Ando

Hiromasa Kinoshita

Takashige Nagato

A sliding-type tripod-shaped constant-velocity universal joint capable of being downsized while reducing induced thrust force. The constant-velocity universal joint includes: an outer race; a tripod including a boss portion and three tripod-shaft portions being inserted into roller grooves; and rollers. And, a shaft-axis-wise width of the tripod-shaft portions is formed smaller as it goes from the root side to the leading-end side in a torque transmission region of the tripod-shaft portions. Further, a torque-transmission-wise width of the tripod-shaft portions is formed greater as it goes from the root side to the leading-end side in the torque transmission region when defining a direction that intersects with the shaft axis and the tripod-shaft portions orthogonally as a torque transmission direction.

Sliding-type tripod-shaped constant-velocity universal joint

A constant velocity jointcomprises an outer racean inner raceballsand a cageThe outer racehas a partially spherical inner surfaceprovided with plural outer ball groovesThe inner racehas a partially spherical outer surfacea provided with plural inner ball groovesarranged to correspond to the outer ball groovesThe ballsare interposed between the outer ball groovesand the inner ball groovesThe radial distance of the outer ball groovesfrom the rotational axis of the outer race increases toward an opening end of the outer racein a predetermined zone H, and a contact angle &#x3b8; between each balland each outer ball groovedecreases toward the opening end of the outer racein the predetermined zone H.

Constant velocity joint

In a tripod-type constant velocity joint having an inner joint member, an outer joint member, and three roller units, the radius R, outer width W, and inner width Wof the outer periphery cylindrical surface of each roller unit, and the radius Rof the center hole of each roller unit satisfy the inequalities: 0.5Rtc(1/cos 0.3&#x2296;&#x2212;1)+(RR)&#x3bc;&#x3c;Wand 1.5Rtc(1&#x2212;cos 0.3&#x2296;)+(R&#x2212;R)&#x3bc;&#x3c;W, where Rtc: the radius of a circle passing through the respective centers of tripod spherical surfaces of the inner joint member, &#x2296;: the maximum joint angle between the outer joint member and the inner joint member, and &#x3bc;: coefficient of friction between each tripod spherical surface and the wall surface of the center hole of the corresponding roller unit.

Tripod-type constant velocity joint

A constant velocity universal joint includes an inner race having an outer peripheral face on which inner grooves are formed, an outer race having an inner peripheral face on which outer grooves are formed, a plurality of balls each engaging with each pair of inner groove and outer groove, and an annular cage disposed between the inner race and the outer race and including window portions for retaining respective balls. A coefficient of sliding friction between the ball and a rolling face on the inner groove with which the ball is in contact, and a coefficient of sliding friction between the ball and a rolling face on the outer groove with which the ball is in contact are larger than a coefficient of sliding friction between the ball and a sliding face on the window portion with which the ball is in contact.

Constant velocity universal joint

A constant velocity universal unit includes an outer joint member whose inner peripheral face is formed with three guide grooves, an inner joint member including three tripod shafts each formed with a tripod spherical face, three roller units each including an outer peripheral face and an inner peripheral face coaxially formed with each other. The guide groove includes a pair of strip-shaped inner side faces formed with a pair of guide projections having a substantially half arc shape in cross section whose diameter is smaller than a height of the inner side face of the guide groove. The constant velocity universal joint further includes an annular recess formed on a substantially center portion in a height direction of the outer peripheral face of the roller unit and engaging with the pair of guide projections in a rolling manner and rotatable relative to a central axis of the guide projection.

A steel material for a high strength constant velocity joint intermediate shaft is provided. The steal material may preferably contain C: 0.46 to 0.52%, Si: 0.6 to 0.8%, Mn: 0.7 to 0.9%, S: 0.01 to 0.05%, Mo: 0.3 to 0.5%, B: 0.0005 to 0.005%, Al: 0.002 to 0.05%, and Ti: 0.02 to 0.09%, restricting N to 0.007% or less, Cr to 0.15% or less, and P to 0.02% or less. A structural percentage of bainite+martensite may be provided which is 40% or more. The steal material may have a hardness of 250 HV to 340 HV. A high strength constant velocity joint intermediate shaft made of that steel material may be provided which has a spline-vanishing part with a surface hardness of about 610 HV to 750 HV, and a ratio t/r of an effective hardened layer depth t and radius r of 0.35 to 0.55, having a flat part with a surface hardness of about 630 HV to 770 HV and a ratio t/r of 0.55 to 1.0, and having a core hardness of about 250 HV to 340 HV.

Steel material for high strength constant velocity joint intermediate shaft and high strength constant velocity joint intermediate shaft

A drive shaft is configured from a shaft body, a shaft portion provided with extensions and boot mounting parts coaxially and integrally formed on ends thereof, and constant velocity joints attached to ends of the extensions via interior members. The outer diameter of intermediate portions of the extensions is smaller than that of the ends and the boot mounting parts. Formed on the opening-sides of the inner surfaces of the exterior members of the constant velocity joints are flanks that face outward and leave a slight clearance with the intermediate portions. Edges forming the boot mounting part sides of the intermediate portions are set to positions corresponding to outer edges of the flanks, and tapered portions connect the edges and the boot mounting parts.

Drive shaft

The contact angle of the ballwith each first guide trackof an inner joint memberis made to become smaller gradually from an opening portion side toward a bottom portion side, and the curvature radius for the first guide trackis made to become larger gradually from the opening portion side toward the bottom portion side. If the contact angle only were made to become smaller gradually from the opening portion side toward the bottom portion side, the contact angle would become too small thereby to cause chattering in rotation to be generated. If the curvature radius only were made to become larger gradually from the opening portion side toward the bottom portion side, a contact ellipse Mdefined by the balland the first guide trackwould become tool small, which would cause the ballto make dents on the surface of the first guide track. However, the aforementioned drawbacks can be obviated by gradually diminishing the contact angle and gradually enlarging the curvature radius from the opening portion side toward the bottom portion side.

A shaft has a shank with a splined portion and a large diameter portion formed in an outer peripheral surface of the shank, the large diameter portion having a diameter that is larger than a diameter of an external periphery of the splined portion. A tapered portion is provided at a side surface of the large diameter portion on the splined portion side. This tapered portion stops a fitting member that is fitted onto the splined portion. In addition, a cut back portion formed at an end portion of the splined portion at the large diameter portion side and the tapered portion are interposed by and continuously connected by a first curved portion, a flat portion and a second curved portion.

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Okazaki, Japan

Kazuyuki Ichikawa