Tapered roller bearing

Abstract

An object of the present invention to provide a tapered roller bearing in which a flange portion is formed at a large-diameter end of an outer ring track surface of an outer ring, capable of providing high moment stiffness and long life without extremely decreasing its pure axial load capacity. The tapered roller bearing comprising: an outer ring 12 having an outer ring track surface 12a on its inner circumferential surface; an inner ring 13 having an inner ring track surface 13a on its outer circumferential surface; a plurality of tapered rollers 14 rotatably disposed between the outer ring track surface 12a and the inner ring track surface 13a; and a retainer 15 having a plurality of pockets for retaining the plurality of tapered rollers 14 at a predetermined interval; the outer ring track surface 12a of the outer ring 12 having a small-diameter end and a large-diameter end, the inner ring track surface 13a of the inner ring 13 having a small-diameter end and a large-diameter end, and, of these four ends, a flange portion 12b that protrudes radially inwardly is formed at the large-diameter end of the outer ring track surface 12a of the outer ring 12; wherein the tapered roller bearing has a contact angle greater than 35° and a roller angle not greater than 3.5°.

Claims

1. A tapered roller bearing comprising: an outer ring having an outer ring track surface on an inner circumferential surface; an inner ring having an inner ring track surface on an outer circumferential surface; a plurality of tapered rollers rotatably disposed between the outer ring track surface and the inner ring track surface; and a retainer having a plurality of pockets for retaining the plurality of tapered rollers at a predetermined interval; the outer ring track surface of the outer ring having a small-diameter end and a large-diameter end, the inner ring track surface of the inner ring having a small-diameter end and a large-diameter end, and, of the small-diameter ends and the large-diameter ends, a flange portion that radially inwardly protrudes is formed at the large-diameter end of the outer ring track surface of the outer ring; wherein the tapered roller bearing has a contact angle of 40° to 50° and a roller angle not greater than 3.5°.

2. The tapered roller bearing according to claim 1, wherein the retainer has: a tapered roller guide surface on an outer diameter side or inner diameter side; one or more tabs for preventing dislocation of the tapered rollers to the side not having the guide surface of the retainer; and a cutout formed on an outer circumferential surface of a large-diameter ring portion of the retainer for making the ring portion thinner than a pillar portion having the guide surface of the retainer.

3. The tapered roller bearing according to claim 2, wherein a relationship expressed as |P−P′|≥C is satisfied, where P represents a circumradius of the roller when the roller is in contact with the guide surface of the retainer; P′ represents a circumradius of the roller when the roller is in contact with the tab of the retainer; and C represents a height of the outer ring flange from the track surface; and the flange has an outer diameter angle γ of 35° to 50°.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an explanatory drawing which schematically shows component forces of an outer ring side rolling element load, an inner ring side rolling element load, and a flange-side rolling element load when a pure axial load is applied to a tapered roller bearing in which a flange portion is formed at a large-diameter end of an outer ring track surface of an outer ring.

(2) FIG. 2 is an explanatory drawing which schematically shows component forces of an outer ring side rolling element load, an inner ring side rolling element load, and a flange side rolling element load when a pure axial load is applied to a tapered roller bearing in which a flange portion is formed at a large-diameter end of an inner ring track surface of an inner ring.

(3) FIG. 3 is an enlarged partial sectional view of a tapered roller bearing according to an embodiment of the present invention, taken by cutting along a pillar portion of a retainer.

(4) FIG. 4 is an enlarged partial sectional view showing a state in which the tapered roller bearing in FIG. 3 is assembled to a housing.

(5) FIG. 5 is a simplified schematic illustration which conceptually shows a contact area between a large flange portion at an outer ring side of the tapered roller bearing in FIG. 3 and a tapered roller.

(6) FIG. 6 is an enlarged view showing a state in which a tapered roller is pressed to contact with a roller guide surface of a retainer of the embodiment in FIG. 3.

(7) FIG. 7 is an enlarged view showing a state in which a tapered roller is pressed to contact with a tab of the retainer of the embodiment in FIG. 3.

(8) FIG. 8A is an enlarged partial sectional view showing a step for insertion of a roller-retainer assay into an outer ring.

(9) FIG. 8B is an enlarged partial sectional view showing a step for insertion of the roller-retainer assay into the outer ring.

(10) FIG. 8C is an enlarged partial sectional view showing a step for insertion of the roller-retainer assay into the outer ring.

(11) FIG. 9 is a front view of the outer ring in the embodiment in FIG. 3.

(12) FIG. 10 is a rear view of the outer ring in the embodiment in FIG. 3.

(13) FIG. 11 is a left side view of the outer ring in the embodiment in FIG. 3.

(14) FIG. 12 is a right side view of the outer ring in the embodiment in FIG. 3.

(15) FIG. 13 is a plan view of the outer ring in the embodiment in FIG. 3.

(16) FIG. 14 is a bottom view of the outer ring in the embodiment in FIG. 3.

(17) FIG. 15 is a sectional view taken in a line A-A in FIG. 9.

(18) FIG. 16 is an enlarged sectional view taken in a line B-B in FIG. 15.

(19) FIG. 17 is a front view of a retainer in the embodiment in FIG. 3.

(20) FIG. 18 is a rear view of the retainer in the embodiment in FIG. 3.

(21) FIG. 19 is a left side view of the retainer in the embodiment in FIG. 3.

(22) FIG. 20 is a right side view of the retainer in the embodiment in FIG. 3.

(23) FIG. 21 is a plan view of the retainer in the embodiment in FIG. 3.

(24) FIG. 22 is a bottom view of the retainer in the embodiment in FIG. 3.

(25) FIG. 23 is a sectional view taken in a line A-A in FIG. 17.

(26) FIG. 24 is a perspective view of the retainer of the embodiment in FIG. 3 viewed from a small-diameter side.

(27) FIG. 25 is a perspective view of the retainer of the embodiment in FIG. 3 viewed from a large-diameter side.

(28) FIG. 26 is a sectional view taken in a line H-H in FIG. 17.

(29) FIG. 27 is an enlarged sectional view taken in a line B-B in FIG. 23.

(30) FIG. 28 is an enlarged sectional view taken in a line C-C in FIG. 17.

(31) FIG. 29 is an enlarged sectional view taken in a line D-D in FIG. 24.

(32) FIG. 30 is an enlarged sectional view taken in a line E-E in FIG. 24.

(33) FIG. 31 is an enlarged sectional view taken in a line F-F in FIG. 25.

(34) FIG. 32 is an enlarged sectional view taken in a line G-G in FIG. 25.

(35) FIG. 33 is an enlarged sectional view taken in a line I-I in FIG. 26.

(36) FIG. 34 is a graph which shows moment stiffness ratio in examples wherein each contact angle is varied.

(37) FIG. 35 is a graph which shows life ratio in examples wherein each contact angle is varied.

(38) FIG. 36 is an enlarged sectional view of a conventional tapered roller bearing, taken by cutting along a pillar portion of a retainer.

(39) FIG. 37 is an enlarged partial sectional view showing a state in which the tapered roller bearing in FIG. 36 is assembled to a housing.

(40) FIG. 38 is a simplified schematic illustration which conceptually shows a contact area between a large flange portion at an inner ring side of the tapered roller bearing in FIG. 36 and a tapered roller.

DESCRIPTION OF EMBODIMENTS

(41) Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

(42) A tapered roller bearing 11 according to the present invention has a steep contact angle α of 40° through 50°, and a gentle roller angle not greater than 3.5°. The tapered roller bearing 11 according to an embodiment as shown in FIG. 3 through FIG. 33 has a contact angle α of 45°, and a roller angle of 3.5°.

(43) As shown in FIG. 3, the tapered roller bearing 11 according to the embodiment of the present invention includes: an outer ring 12 having an outer ring track surface 12a on its inner circumferential surface; an inner ring 13 having an inner ring track surface 13a on its outer circumferential surface; a plurality of tapered rollers 14 rotatably disposed between the outer ring track surface 12a and the inner ring surface 13a; and a retainer 15 having a plurality of pockets for retaining the plurality of tapered rollers 14 at a predetermined interval.

(44) The tapered roller bearing 11 according to the present invention is intended for high moment stiffness with a steep contact angle α of 40 through 50°. The tapered roller bearing 11 according to the embodiment in FIG. 3 has a contact angle α of 45°.

(45) In the tapered roller bearing 11 according to the embodiment of the present invention, the outer ring track surface 12a of the outer ring 12 has a small-diameter end and a large-diameter end, the inner ring track surface 13a of the inner ring 13 has a small-diameter end and a large-diameter end, and, of these four ends, a flange portion 12b that radially inwardly protrudes is formed only at the large-diameter end of the outer ring track surface 12a of the outer ring 12.

(46) The small-diameter end of the inner ring 13 does not have a small flange, and the rollers have an increased length as much as the length of eliminated small flange, for increased load capacity. At the same time, the flange portion 12b that radially inwardly protrudes is formed only at the large-diameter end of the outer ring track surface 12a of the outer ring 12. The large-diameter end of the inner ring track surface 13a of the inner ring 13 does not have a flange portion.

(47) The tapered roller bearing 11 with the steep contact angle of 40 through 50° has a large space in its axial direction between the large-diameter end of the outer ring track surface 12a of the outer ring 12 and the large-diameter-side end surface of the inner ring 13. In the present invention, the flange portion 12b that radially inwardly protrudes is formed by using the space.

(48) By forming the flange portion 12b that radially inwardly protrudes only at the large-diameter end of the outer ring track surface 12a of the outer ring 12 and by eliminating the flange portion at the large-diameter end of the inner ring track surface 13a of the inner ring 13, it becomes possible to compactify its axial dimension.

(49) Namely, as indicated in alternate long and two short dashes lines in FIG. 3, when the flange portion 12b is formed at the large-diameter end of the inner ring track surface 13a of the inner ring 13, the axial width will be T′. By eliminating the flange portion at the large-diameter end of the inner ring track surface 13a of the inner ring 13, it becomes possible to decrease the axial width of the inner ring 13. When the flange portion 12b that radially inwardly protrudes is formed at the large-diameter end of the outer ring track surface 12a of the outer ring 12, the axial width will be T. Therefore, it is possible to compactify the axial width by T′−T.

(50) By forming the flange portion 12b that radially inwardly protrudes at the large-diameter end of the outer ring track surface 12a of the outer ring 12 as disclosed in the present invention, it becomes possible to increase stiffness of the flange portion compared with a conventional tapered roller bearing 1 as shown in FIG. 36 which has a flange portion formed at the large-diameter end of the inner ring track surface 13a of the inner ring 13.

(51) Namely, when comparing a case where the flange portion 12b that radially inwardly protrudes is formed at the large-diameter end of the outer ring track surface 12a of the outer ring 12 as shown in FIG. 3 with a case where a flange portion 3b is formed at the large-diameter end of the inner ring track surface 3a of the inner ring 3 as shown in FIG. 36, it is confirmed that even if the height of the flange portion C (a radial distance from an intersection between the track surface and the flange surface to an apex of the flange portion) is the same, a contact area between the roller end surface and the outer ring flange surface as shown in FIG. 5 is greater, by approximately 7 percent, than a contact area between the roller end surface and the inner ring flange surface of the conventional arrangement as shown in FIG. 38. This means that induced thrust force generated in the roller is received by the greater area when the outer ring has a flange, which decreases stress at the place of contact, leading to decreased contact strain between the roller end surface and the flange surface.

(52) Also, in the conventional arrangement as shown in FIG. 36, where the flange portion 3b is formed at the large-diameter end of the inner ring 3, the induced thrust force generated in a tapered roller 4 is received by the flange portion 3b as indicated by white arrows in FIG. 37, and this poses a potential problem that a bending stress acting on the flange portion 3b may cause the flange portion 3b to distort. On the contrary, according to the present invention as shown in FIG. 4, where the flange portion 12b is formed at the large-diameter end of the outer ring 12, it is possible, as indicated by white arrows, to receive the induced thrust force generated in a tapered roller 14, i.e., the bending stress acting on the flange portion 12b of the outer ring 12, with the housing 6, and this increases stiffness of the flange portion 12b. Note that in the conventional arrangement as shown in FIG. 36, a reference sign 2 represents an outer ring, a sign 2a represents an outer ring track surface, and a sign 5 represents a retainer.

(53) In the present invention, the retainer 15 may be made of a resin.

(54) As shown in FIG. 6 and FIG. 7, the retainer 15 has a large-diameter ring portion 15a on its large-diameter side; a small-diameter ring portion 15b on its small-diameter side; roller guide surfaces 15c on its outer diameter portion for guiding the tapered rollers 14; and tabs 15d on its inner diameter surface for retaining the tapered rollers 14. However, the position of the roller guide surfaces 15c for guiding the tapered rollers 14 and the tabs 15d for retaining the tapered rollers 14 may be reversed. Also, the retainer 15 is provided with, on an outer circumferential surface of the large-diameter ring portion 15a, a cutout 15e to avoid interference with the flange portion 12b of the outer ring 12.

(55) As shown in FIG. 6, a circumradius of the roller is represented with P when the tapered roller 14 is pressed to contact with the roller guide surface 15c which is at the outer diameter side of the retainer 15; as shown in FIG. 7, a circumradius of the roller is represented with P′ when the tapered roller 14 is pressed to contact with the tabs 15d which are at the inner diameter side of the retainer 15. With these circumradii defined as the above, evaluation was made by inserting a roller-retainer assay into the outer ring 12 following steps as shown in FIGS. 8A, 8B and 8C, to see easiness of insertion by not varying the flange height C of the flange portion 12b but varying the contact angle α, flange outer diameter angle γ, and |P−P′|. Results are shown in Tables 7 through 11.

(56) From the results in Table 7 through Table 11, it was confirmed that those bearings which have their contact angles set to 40 through 50° exhibit better insertability of the roller-retainer assay when |P−P′|≥C and the flange's large-diameter-side angle γ is 35° through 50°.

(57) TABLE-US-00007 TABLE 7 Flange Outer Easiness of Contact Angle α° Diameter Angle γ° C |P − P′| Insertion 35 30 1 0.8 x 35 30 1 1 x 35 35 1 0.8 x 35 35 1 1 x 35 45 1 0.8 x 35 45 1 1 x 35 45 1 2 x 35 50 1 0.8 x 35 50 1 1 x 35 50 1 2 x 35 55 1 1 x 35 55 1 2 x

(58) TABLE-US-00008 TABLE 8 Flange Outer Easiness of Contact Angle α° Diameter Angle γ° C |P − P′| Insertion 40 30 1 0.8 x 40 30 1 1 x 40 35 1 0.8 x 40 35 1 1 ∘ 40 45 1 0.8 x 40 45 1 1 ∘ 40 45 1 2 ∘ 40 50 1 0.8 x 40 50 1 1 ∘ 40 55 1 2 ∘ 40 55 1 1 x 40 55 1 2 x

(59) TABLE-US-00009 TABLE 9 Flange Outer Easiness of Contact Angle α° Diameter Angle γ° C |P − P′| Insertion 45 30 1 0.8 x 45 30 1 1 x 45 35 1 0.8 x 45 35 1 1 ∘ 45 45 1 0.8 x 45 45 1 1 ∘ 45 45 1 2 ∘ 45 50 1 0.8 x 45 50 1 1 ∘ 45 50 1 2 ∘ 45 55 1 1 x 45 55 1 2 x

(60) TABLE-US-00010 TABLE 10 Flange Outer Easiness of Contact Angle α° Diameter Angle γ° C |P − P′| Insertion 50 30 1 0.8 x 50 30 1 1 x 50 35 1 0.8 x 50 35 1 1 ∘ 50 45 1 0.8 x 50 45 1 1 ∘ 50 45 1 2 ∘ 50 50 1 0.8 x 50 50 1 1 ∘ 50 50 1 0 ∘ 50 55 1 1 x 50 55 1 2 x

(61) TABLE-US-00011 TABLE 11 Flange Outer Easiness of Contact Angle α° Diameter Angle γ° C |P − P′| Insertion 55 30 1 0.8 x 55 30 1 1 x 55 35 1 0.8 x 55 35 1 1 x 55 45 1 0.8 x 55 45 1 1 x 55 45 1 2 x 55 50 1 0.8 x 55 50 1 1 x 55 50 1 2 x 55 55 1 1 x 55 55 1 2 x

(62) The tapered roller bearing 11 according to the present invention, having the contact angle of 40 through 50°, has moment stiffness expressed in a graph in FIG. 34 and life ratio expressed in a graph in FIG. 35 when only the contact angle is varied, with an external load, the bearing's PCD, and size and quantity of the rollers maintained constant. From the graphs given in FIG. 34 and FIG. 35, overall evaluation was made relative to each contact angle. Results are shown in Table 12, i.e., it was confirmed that by setting the contact angle in the range of 40 through 50°, it becomes possible to improve both the moment stiffness and the life of the bearing.

(63) TABLE-US-00012 TABLE 12 Contact Angle 25 30 35 40 45 50 55 60 65 Moment X ◯ — ◯ ◯ ◯ ⊚ ◯ ◯ Stiffness Life X X — ◯ ⊚ ◯ X X X Total Evaluation X X — ⊚ ⊚ ⊚ X X X

(64) The present invention is not limited to any of the embodiments described thus far, and it is obvious that the invention may be modified in many other ways within the scope of the present invention. The scope of the present invention is defined by the CLAIMS and includes all equivalents thereto and any variations therein.

REFERENCE SIGNS LIST

(65) 11: Bearing 12: Outer ring 12a: Outer Ring Track Surface 12b: Flange portion 13: Inner ring 13a: Inner ring track surface 15: Retainer 15a: Large-Diameter Ring Portion 15b: Small-Diameter Ring Portion 15c: Guide Surface 15d: Claw 15e: Cutout