Ntn Corporation

Tomoki Matsushita

Takashi Kawai

Takanori Ishikawa

Nozomi Isobe

Takashi Ueno

Yasuhiro Kanbori

The present invention provides a bearing device for vehicle wheel reducing the occurrence of abnormal heat generation caused by metal contact and enhancing anti-seizing properties. Each of the tapered rollershas a large diameter-side end surface, the inner raceway surface, and the large flange part. The large flange partincludes a chamfered partand a rounded part. The large flange parthas a large flange part-side cutout part, the large diameter-side end surfaceof each of the tapered rollershas a tapered roller-side cutout parthaving a circular shape formed coaxially with the large diameter-side end surface, and a clearance of the large diameter-side end surfaceas viewed from a contact point between the large diameter-side end surfaceand the guide surfaceis greater than or equal to 15 μm.

Bearing device for vehicle wheel

A difference between a maximum value and a minimum value of arithmetic mean roughness Ra of an annular surface region in contact with a larger flange surface, in a larger end face of the tapered roller, is not greater than 0.02 &#x3bc;m. A value of a ratio R/Ris not smaller than 0.75 and not greater than 0.87 where R represents a set radius of curvature of the larger end face of the tapered roller and Rrepresents a distance from a point which is an apex of a cone angle of the tapered roller to the larger flange surface of the inner ring. A ratio R/R is not lower than 0.5 where Rrepresents an actual radius of curvature after grinding of the larger end face of the tapered roller and R represents a set radius of curvature.

Tapered roller bearing

A tapered roller bearing for an automobile includes an inner ring including a raceway surface having a tapered shape on an outer periphery, an outer ring including a raceway surface having a tapered shape on an inner periphery, a plurality of tapered rollers incorporated into a space defined between the raceway surfaces, and a retainer configured to receive the tapered rollers. The inner and outer rings are each made of carburized steel, and the raceway surfaces of the inner and outer rings each have a straight generating line shape. The tapered rollers each are made of high carbon chromium bearing steel, and each have a rolling surface including a straight portion, which is formed at a center portion in an axial direction, and crowning portions, which extend from the straight portion to both end portions. The crowning portions are each formed of logarithmic crowning.

Tapered roller bearing for automobile

Two projecting portions (and) configured to guide a tapered roller () on distal end surfaces thereof are formed on a side surface () of a pillar portion () of a retainer () so as to be separated apart from each other in a roller axis direction. The projecting portions (and) are separated apart from each other in the roller axis direction with respect to both a small-diameter-side annular portion () and a large-diameter-side annular portion (). The projecting portions (and) each have a force-fit margin (F).

Provided is a tapered roller bearing () which is to be used for a pilot portion and an idler portion of a synchronous mesh-type transmission in which a component corresponding to a bearing outer ring () is formed of a gear (), wherein a ratio L/Dw of a roller length (L) of a tapered roller () serving as a rolling element to a roller diameter (Dw) is set to 1.7 or more, wherein a rolling surface () of the tapered roller () includes a straight portion () in a center portion of the rolling surface () in an axial direction and crowning portions () extending from the straight portion () to both end portions, and wherein the crowning portions () are each formed of logarithmic crowning.

A value of R/Ris not smaller than 0.75 and not greater than 0.87 where R represents a reference radius of curvature of a larger end face of a roller and Rrepresents a distance from an apex of a cone angle of the roller to a larger flange surface of an inner ring. A distance from an outermost surface of at least any one of an outer ring, the inner ring, and a plurality of rollers to a bottom of a nitrogen enriched layer is not shorter than 0.2 mm. A crowning profile is formed on a rolling surface of the roller.

In a tapered roller bearing, a cage includes a plurality of trapezoidal pockets and the pockets accommodate and hold a plurality of rollers. A notch having a width is provided in a post on a smaller width side of the pocket of the cage from a boundary between a smaller annular portion and a post toward a larger annular portion. Lubricating oil which flows from an inner diameter side of the cage toward an inner ring is quickly discharged through the notch toward an outer ring on an outer diameter side. A distance from an outermost surface of at least any one of the outer ring and the inner ring of the roller and a plurality of rollers to a bottom of a nitrogen enriched layer is equal to or longer than 0.2 mm. A rolling surface of the roller is provided with a logarithmic crowning profile.

A tapered roller bearing includes inner and outer rings having tapered raceway surfaces. The inner ring also includes large-collar and small-collar surfaces respectively on large-diameter and small-diameter sides of its raceway surface. A plurality of tapered rollers are arrayed between the raceway surfaces. Each of the tapered rollers has a large end surface that contacts and is guided by the large-collar surface. A set curvature radius (R) of the large end surface of each of the tapered rollers and a base curvature radius (R) from a vertex of a cone angle of each of the tapered rollers to the large-collar surface has a ratio R/Rin a range of 0.75 to 0.87, and when Rrepresents an actual curvature radius of the large end surface, a ratio R/R is equal to or larger than 0.5.

A tapered roller bearing includes inner and outer rings including raceway surfaces having tapered shapes on their outer and inner peripheries, respectively, tapered rollers between the raceway surfaces, and a retainer configured to receive the tapered rollers. At least the raceway surface of the inner ring includes cut crowning of a complex curve including a center curve and end portion curves formed on both sides of the center curve each have a curvature radius smaller than a curvature radius of the center curve. The tapered rollers each have a rolling surface including a straight portion and logarithmic crowning portions formed on both sides of the straight portion. When the raceway surface of the inner ring has an effective raceway surface width represented by LG, and the straight portion of the rolling surface of the tapered roller has a width represented by LW, 0.7&#x2264;LW/LG&#x3c;0.95 is satisfied.

A washer () to be mounted to an end surface () of an inner ring includes an extension portion () extending along an outer peripheral surface () of the inner ring. The extension portion () includes an engaging projection portion () to be engaged with an engaging recessed portion () formed in the outer peripheral surface () of the inner ring. The engaging projection portion () includes a rounded curved surface portion (), and a flat surface portion () formed continuously with a forward side in a pressing direction of the rounded curved surface portion () and inclined radially outward.

Rolling bearing

A tapered roller bearing includes an outer ring, an inner ring, a tapered roller interposed between the outer ring and the inner ring, and a cage holding the tapered roller. The tapered roller bearing is for being used in an idler portion of an automobile transmission that switches between an idle state in which the outer ring rotates freely in relation to the inner ring and a shift state in which the outer ring rotates synchronously with the inner ring. In one embodiment, the tapered roller bearing has a ratio of roller dynamic load rating Cr to static load rating Cor of Cor/Cr&#x2267;1.4. In an alternative embodiment, MoSprocessing is performed on a surface of the tapered roller and the tapered roller bearing has a ratio of roller dynamic load rating Cr to static load rating Cor of Cor/Cr&#x2267;1.3.

A tapered roller bearing achieves improvement in manufacturability and a longer life. The tapered roller bearing includes an outer ring, an inner ring, a plurality of tapered rollers disposed between raceways of the inner ring and the outer ring. A cage holds each tapered roller. A shoulder section that receives a large end face of the tapered roller is provided on a large-diameter side of the inner ring so as to project towards an outer-diameter side. A raceway that reaches from the shoulder section to the small diameter end is formed. An engaging section that engages with the shoulder section on the inner ring is provided on a large-diameter side of the cage so as to project towards an inner diameter direction. The engaging section is disposed such as to fit within a width of a corresponding pocket when viewed from an axial direction.

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Shizuoka, Japan

Tomoki Matsushita