JP7570179B2 - Tapered roller bearings - Google Patents

Description

This invention relates to a tapered roller bearing.

Tapered roller bearings, which are bearings capable of supporting radial and axial loads simultaneously, are often used in automobile transmissions (manual transmissions (MT), automatic transmissions (AT), dual clutch transmissions (DCT), continuously variable transmissions (CVT), hybrid transmissions) and differential mechanisms (for example, Patent Document 1).

The tapered roller bearing in Patent Document 1 has an outer ring with a tapered outer ring raceway surface on its inner circumference, an inner ring with a tapered inner ring raceway surface on its outer circumference, multiple tapered rollers assembled at intervals in the circumferential direction between the outer ring raceway surface and the inner ring raceway surface, and an annular cage that maintains the circumferential spacing of the multiple tapered rollers. The outer circumference of the inner ring is provided with a large rib that guides the large end face of each tapered roller, and a small rib that faces the small end face of each tapered roller in the axial direction.

Meanwhile, regulations on fuel efficiency for automobiles have become increasingly strict in recent years, which has led to demands for further reductions in rotational torque for parts used in automobile transmissions and differential mechanisms. In particular, tapered roller bearings, in which the tapered rollers as the rolling elements roll on the inner ring raceway surface while in sliding contact with the large rib of the inner ring, tend to have a higher rotational torque than ball bearings, which use balls as rolling elements, and so there is a growing need to reduce the rotational torque of tapered roller bearings.

JP 2007-024168 A

Tapered roller bearings are assembled as follows: first, tapered rollers are inserted into each pocket of the cage, and then the cage is attached to the outer periphery of the inner ring. This forms the inner ring assembly (the inner ring, tapered rollers, and cage integrated together). The inner ring assembly is then inserted into the outer ring, completing the assembly of the tapered roller bearing. At this point, when the tapered rollers are inserted into each pocket of the cage and attached to the outer periphery of the inner ring, the tapered rollers need to get over the small rib on the inner ring, but because the cage restricts the tapered rollers from moving radially outward, they cannot get over the small rib with the dimensions remaining as they are.

Therefore, when the cage is made of iron, in order to allow the tapered rollers to ride over the small rib, the usual method is to first expand the cage through plastic deformation to increase the inscribed circle diameter of the tapered rollers, then allow the tapered rollers to ride over the small rib in this state, and then crimp the cage to reduce the inscribed circle diameter of the tapered rollers.

On the other hand, when the cage is made of resin, the commonly used method is that when the tapered rollers ride up onto the small rib, the force that the tapered rollers receive from the small rib in the radial expansion direction causes the cage to elastically deform, and the elastic deformation of the cage causes the tapered rollers to climb over the small rib.

If the cage is made of resin, when the cage elastically deforms in the radial expansion direction, the elastic restoring force of the cage presses the tapered rollers strongly against the small flange, which may cause damage to the tapered rollers. On the other hand, if the cage is made of iron, the cage is plastically deformed, so there is no risk of the tapered rollers being pressed against the small flange and damaged; however, the assembly process requires a lot of man-hours, and since the cage is plastically deformed once, fine adjustments are necessary to improve the dimensional accuracy of the cage, which makes it difficult to reduce the rotational torque of the cage.

The problem that this invention aims to solve is to provide a tapered roller bearing that has low rotational torque and can prevent the tapered rollers from being damaged during assembly.

In order to solve the above problems, the present invention provides a tapered roller bearing having the following configuration.
An outer ring having a conical outer ring raceway on its inner circumference;
an inner ring arranged coaxially inside the outer ring and having a conical inner ring raceway surface on an outer periphery;
a plurality of tapered rollers assembled at intervals in a circumferential direction between the outer ring raceway surface and the inner ring raceway surface;
and an annular cage that maintains the circumferential spacing of the plurality of tapered rollers,
a large rib that contacts a large end face of each of the tapered rollers and a small rib that faces a small end face of each of the tapered rollers in the axial direction are provided on an outer periphery of the inner ring;
The retainer has a large diameter side annular portion extending in the circumferential direction along the large end faces of the tapered rollers, a small diameter side annular portion extending in the circumferential direction along the small end faces of the tapered rollers, and a plurality of pillar portions connecting the large diameter side annular portion and the small diameter side annular portion,
the large diameter side annular portion, the small diameter side annular portion, and the plurality of column portions are integrally formed from a resin composition,
the plurality of column portions are arranged such that the entirety of each column portion is located radially outward of a pitch cone formed by a locus of centers of tapered roller angles when the plurality of tapered rollers revolve,
the small diameter side annular portion has an inward flange shape extending radially inward from an axial end of the column portion while intersecting the pitch cone,
the small rib has a tapered outer circumferential surface that gradually becomes larger in diameter as it approaches the small end surface of the tapered roller,
a small diameter side annular portion having an inner circumferential surface facing the outer circumferential surface of the small rib, the inner circumferential surface being tapered so as to gradually increase in diameter as it approaches the small end face of the tapered roller, said tapered roller bearing.

In this way, the outer circumferential surface of the small rib of the inner ring is tapered so that the diameter gradually increases as it approaches the small end face of the tapered roller, so that when the tapered rollers are inserted into each pocket of the cage and then attached to the outer periphery of the inner ring to assemble the tapered roller bearing, the elastic deformation of the cage that is necessary for the tapered rollers to get over the small rib can be suppressed. Also, when the tapered rollers are pressed against the small rib by the elastic restoring force of the cage, the tapered rollers and the small rib come into contact over a relatively wide area, so that the tapered rollers can be prevented from being damaged by the force they receive from the small rib. Furthermore, the small diameter annular portion of the cage is formed into an inward flange shape that extends radially inward from the axial end of the column, intersecting the pitch cone, and the inner peripheral surface of the small diameter annular portion and the outer peripheral surface of the small flange face each other and are inclined in the same direction, so that the small diameter annular portion of the cage and the small flange of the inner ring block the axial end of the space between the column and the inner ring raceway surface, and the radial width of the flange-shaped small diameter annular portion can be widened, making it difficult for lubricating oil to flow into the bearing. This makes it possible to reduce the amount of lubricating oil that flows into the bearing due to the pump action while the bearing is rotating, and to keep the rotational torque due to the agitation resistance of the lubricating oil inside the bearing low.

It is preferable that the outer diameter of the small flange at its largest point is set to be larger than the inscribed circle diameter of the small diameter end of each of the tapered rollers.

This effectively prevents the inner ring from coming out of the cage and causing the inner ring, tapered rollers, and cage to come apart.

It is preferable that the inclination angle of the outer peripheral surface of the small flange is set to be the same as the inclination angle of the inner ring raceway surface or the difference between the inclination angle and the inner ring raceway surface is within 5°.

In this way, when the tapered roller bearing is assembled, the outer circumferential surface of the small flange comes into contact with the tapered roller over its entire axial length when the tapered roller is pressed against the small flange by the elastic restoring force of the cage, effectively preventing the tapered roller from being damaged by the force applied by the small flange.

It is preferable that the small rib further has an arc-shaped R surface that smoothly connects to the outer peripheral surface of the small rib, and a small rib surface that is connected to the R surface and faces the small end surface of the tapered roller.

This effectively prevents the tapered rollers from being damaged when they pass over the small flange during assembly of the tapered roller bearing.

It is preferable that the inclination angle of the inner peripheral surface of the small diameter annular portion is set to be the same as the inclination angle of the outer peripheral surface of the small flange, or the difference between the inclination angle and the small flange is within 5°.

In this way, the inner circumferential surface of the small diameter annular portion and the outer circumferential surface of the small flange become approximately parallel, narrowing the gap between them, effectively preventing lubricating oil from outside the bearing from flowing into the bearing through the gap between the inner circumferential surface of the small diameter annular portion and the outer circumferential surface of the small flange.

It is preferable that the small diameter annular portion is formed so that the distance between the inner peripheral surface and the outer peripheral surface of the small flange is 1.5 mm or less.

In this way, since the gap between the inner circumferential surface of the small diameter side annular portion and the outer circumferential surface of the small flange is narrow, it is possible to effectively prevent lubricating oil outside the bearing from flowing into the inside of the bearing through the gap between the inner circumferential surface of the small diameter side annular portion and the outer circumferential surface of the small flange.

It is preferable that the end of the outer circumferential surface farther from the small end face of the tapered roller is disposed closer to the small end face of the tapered roller than the end of the inner circumferential surface farther from the small end face of the tapered roller.

In this way, the end of the gap between the inner circumferential surface of the small diameter side annular portion and the outer circumferential surface of the small rib that is farther from the small end face of the tapered roller is covered from the radial outside by the small diameter side annular portion, making it difficult for lubricating oil outside the bearing to enter the gap between the inner circumferential surface of the small diameter side annular portion and the outer circumferential surface of the small rib, effectively preventing lubricating oil outside the bearing from flowing into the inside of the bearing through the gap between the inner circumferential surface of the small diameter side annular portion and the outer circumferential surface of the small rib.

The axial length of the outer peripheral surface can be set to be greater than the axial length of the inner peripheral surface, so that the entire surface of the inner peripheral surface faces the outer peripheral surface.

In this way, the entire inner peripheral surface of the small diameter annular portion of the retainer faces the outer peripheral surface of the small flange to form a labyrinth gap, which has the effect of preventing lubricating oil from outside the bearing from flowing into the inside of the bearing.

If the small diameter annular portion of the cage is made into an inward flange shape that extends radially inward, it is possible to reduce the amount of lubricating oil that flows into the inside of the bearing, but on the other hand, the cage becomes more difficult to deform in the radial direction, which may reduce the ease of assembly of the tapered roller bearing. Therefore, it is preferable to use a resin material to which an elastomer has been added as the resin composition.

This increases the flexibility of the cage, making it easier to insert tapered rollers into each pocket of the cage and then attach them to the outer periphery of the inner ring, improving the ease of assembly of the tapered roller bearing. In other words, by making the small-diameter annular portion of the cage an inward flange shape that extends radially inward, it is possible to ensure the effect of reducing the agitation torque of the lubricating oil inside the bearing while also ensuring the ease of assembly of the tapered roller bearing.

It is preferable to further add fiber reinforcing material to the resin material.

In this way, the reduction in the strength of the cage caused by adding elastomer to the resin material can be compensated for by the fiber reinforcement material. This makes it possible to achieve both ease of assembly of the tapered roller bearing and strength of the cage.

The resin material may be polyamide or polyphenylene sulfide.

In the tapered roller bearing of this invention, the outer circumferential surface of the small rib of the inner ring is tapered so that the diameter gradually increases as it approaches the small end face of the tapered roller, so that when the tapered rollers are inserted into each pocket of the cage and then attached to the outer periphery of the inner ring to assemble the tapered roller bearing, the elastic deformation of the cage that is necessary for the tapered rollers to get over the small rib can be suppressed. Also, when the tapered rollers are pressed against the small rib by the elastic restoring force of the cage, the tapered rollers and the small rib come into contact over a relatively wide area, so that the tapered rollers can be prevented from being damaged by the force they receive from the small rib. Furthermore, the small diameter annular portion of the cage is formed into an inward flange shape that extends radially inward from the axial end of the column, intersecting the pitch cone, and the inner peripheral surface of the small diameter annular portion and the outer peripheral surface of the small flange face each other and are inclined in the same direction, so that the small diameter annular portion of the cage and the small flange of the inner ring block the axial end of the space between the column and the inner ring raceway surface, and the radial width of the flange-shaped small diameter annular portion can be widened, making it difficult for lubricating oil to flow into the bearing. This makes it possible to reduce the amount of lubricating oil that flows into the bearing due to the pump action while the bearing is rotating, and to keep the rotational torque due to the agitation resistance of the lubricating oil inside the bearing low.

1 is a cross-sectional view of a tapered roller bearing according to an embodiment of the present invention; FIG. 2 is an enlarged view of the vicinity of the small diameter side annular portion of the retainer of FIG. 1; FIG. 2 is a diagram showing the state in which tapered rollers are inserted into the pockets of the cage during the assembly process of the tapered roller bearing shown in FIG. FIG. 4 shows the state in which the inner ring is inserted into the cage shown in FIG. 3, the tapered rollers ride up onto the small flange of the inner ring, and the cage is elastically deformed and expanded in diameter. FIG. 5 shows the state in which the tapered roller shown in FIG. 4 has climbed over the small rib of the inner ring. FIG. 2 is a diagram showing a modified example in which the width of the small flange shown in FIG. 1 is narrowed. FIG. 2 is a diagram showing a modified example of the tapered roller bearing shown in FIG. 1 . FIG. 2 is a diagram showing another modified example of the tapered roller bearing shown in FIG. 1. FIG. 2 is a diagram showing yet another modified example of the tapered roller bearing shown in FIG. 1. FIG. 2 is a diagram showing yet another modified example of the tapered roller bearing shown in FIG. 1. FIG. 2 is a cross-sectional view showing a portion of a transmission using the tapered roller bearing shown in FIG. 1 and its surrounding area. FIG. 2 is a cross-sectional view showing a portion of a differential mechanism using the tapered roller bearing shown in FIG. 1 and its surrounding area.

Figure 1 shows a tapered roller bearing 1 according to an embodiment of the present invention. This tapered roller bearing 1 has an outer ring 3 with a tapered outer ring raceway surface 2 on its inner circumference, an inner ring 5 with a tapered inner ring raceway surface 4 on its outer circumference, a number of tapered rollers 6 assembled at intervals in the circumferential direction between the outer ring raceway surface 2 and the inner ring raceway surface 4, and an annular cage 7 that maintains the spacing between the tapered rollers 6.

The inner ring 5 is arranged coaxially inside the outer ring 3. A small rib 8 located on the small diameter side of the inner ring raceway surface 4 and a large rib 9 located on the large diameter side of the inner ring raceway surface 4 are formed on the outer circumference of the inner ring raceway surface 5. The inner ring raceway surface 4 faces the radially inside of the outer ring raceway surface 2. The tapered rollers 6 are in rolling contact with the outer ring raceway surface 2 and the inner ring raceway surface 4. When the bearing rotates, each tapered roller 6 rotates while revolving around the central axis of the inner ring 5 between the outer ring raceway surface 2 and the inner ring raceway surface 4.

The small rib 8 is formed to protrude radially outward from the inner ring raceway surface 4 so as to axially face the small end face 10 of the tapered roller 6. The small rib 8 restricts the movement of the inner ring raceway surface 4 of the tapered roller 6 toward the small diameter side, and this restriction prevents the inner ring 5 from slipping out of the cage 7. The large rib 9 is formed to protrude radially outward from the inner ring raceway surface 4 so as to axially face the large end face 11 of the tapered roller 6. When the bearing rotates, the large end face 11 of the tapered roller 6 and the large rib 9 of the inner ring 5 support part of the axial load through contact involving sliding.

The retainer 7 has a large diameter side annular portion 12 that extends circumferentially along the large end faces 11 of the tapered rollers 6, a small diameter side annular portion 13 that extends circumferentially along the small end faces 10 of the tapered rollers 6, and a number of pillar portions 14 that pass between adjacent tapered rollers 6 in the circumferential direction and connect the large diameter side annular portion 12 and the small diameter side annular portion 13.

The large diameter side annular portion 12, the small diameter side annular portion 13, and the multiple column portions 14 define multiple pockets 15 that each house a multiple tapered roller 6. Here, the large diameter side annular portion 12 and the small diameter side annular portion 13 define both axial ends of the pocket 15, and the column portions 14 define both circumferential ends of the pocket 15.

The column portion 14 has roller guide surfaces 16 formed on both circumferential sides of the column portion 14, a conical inner peripheral surface 17 that connects to the radial inner end of the roller guide surface 16, and a conical outer peripheral surface 18 that connects to the radial outer end of the roller guide surface 16. The roller guide surface 16 is a flat surface or a concave conical surface that extends along the outer periphery of the tapered roller 6 so as to contact and guide the tapered roller 6. The cage 7 is positioned by the contact between the column portion 14 and the tapered roller 6. In other words, the cage 7 is not in contact with the inner ring 5 and is not in contact with the outer ring 3 either.

The pillar portion 14 also has a triangular recess 19 recessed circumferentially relative to the roller guide surface 16. The triangular recess 19 is a triangular region whose radial width gradually narrows from one side of the triangular region, the corner where the pillar portion 14 and the large diameter side annular portion 12 connect, toward the small diameter side annular portion 13, recessed circumferentially relative to the roller guide surface 16. The triangular recess 19 is the portion through which the portion of the mold that molds the large diameter side annular portion 12 passes when the retainer 7 is resin-molded using a mold (not shown).

The large diameter side annular portion 12, the small diameter side annular portion 13, and the multiple pillar portions 14 that make up the retainer 7 are seamlessly formed as a single piece from a resin composition. The resin composition that forms the retainer 7 can be made of resin material alone, but here, a resin material to which an elastomer and fiber reinforcement material have been added is used.

Polyamide (PA) or super engineering plastics can be used as the base resin material of the resin composition. As polyamides, polyamide 66 (PA66), polyamide 46 (PA46), polynonamethylene terephthalamide (PA9T), etc. can be used. As super engineering plastics, polyphenylene sulfide (PPS) can be used. It is preferable to use PPS as the base resin material of the resin composition that forms the retainer 7, since PPS has excellent heat resistance, oil resistance, and low water absorption. The elastomer added to the resin material is, for example, a thermoplastic elastomer.

As fiber reinforcement to be added to the resin material, glass fiber, carbon fiber, aramid fiber, etc. can be used. When glass fiber is used as the fiber reinforcement, the glass fiber content in the fiber reinforcement can be 10 to 50% by weight (preferably 20 to 40% by weight, more preferably 25 to 35% by weight). The combination of the resin material, elastomer, and fiber reinforcement can be freely selected as appropriate.

The columnar portions 14 are arranged so that the entire columnar portion 14 is located radially outward from the pitch cone P, which is the locus of the center of the tapered roller angle when the multiple tapered rollers 6 revolve. In other words, the columnar portion 14 is formed so that its inner circumferential surface 17 is located radially outward from the pitch cone P over the entire length of the columnar portion 14. The center of the tapered roller angle is the central axis of the conical surface on the outer periphery of the tapered roller 6, and is also the rotation axis of the tapered roller 6.

The small diameter side annular portion 13 has an inward flange shape that extends radially inward from the axial end of the column portion 14 (the end connected to the small diameter side annular portion 13) and intersects with the pitch cone P. The small diameter side annular portion 13 has an inner peripheral surface 21 that faces the outer peripheral surface 20 of the small flange 8. The inner peripheral surface 21 of the small diameter side annular portion 13 is tapered so that the diameter gradually increases as it approaches the small end face 10 of the tapered roller 6. The outer peripheral surface 20 of the small flange 8 is also tapered so that the diameter gradually increases as it approaches the small end face 10 of the tapered roller 6.

The inclination angle θ1 of the outer peripheral surface 20 of the small flange 8 is set to be the same as the inclination angle θ2 of the inner ring raceway surface 4 or the difference is within 5° (preferably within 3°, more preferably within 2°). The inclination angle θ3 of the inner peripheral surface 21 of the small diameter side annular portion 13 is set to be the same as the inclination angle θ1 of the outer peripheral surface 20 of the small flange 8 or the difference is within 5° (preferably within 3°, more preferably within 2°).

As shown in FIG. 2, the small flange 8 further has an R surface 23 having a cross-sectional arc shape that smoothly connects to the outer peripheral surface 20 of the small flange 8, and a small flange surface 22 formed by connecting to the R surface 23. The small flange surface 22 is a conical surface that faces the small end surface 10 of the tapered roller 6. The arc radius r of the cross section of the R surface 23 can be set in the range of 0.2 mm to 3.0 mm (preferably 1.0 mm to 2.5 mm, more preferably 1.5 mm to 2.5 mm). By setting the arc radius r of the cross section of the R surface 23 to 0.2 mm or more (preferably 1.0 mm or more, more preferably 1.5 mm or more), it is possible to effectively prevent the tapered roller 6 from being damaged when assembling the tapered roller bearing 1 as described later. By setting the arc radius r of the cross section of the R surface 23 to 3.0 mm or less (preferably 2.5 mm or less), it is possible to reduce the processing cost of the R surface 23.

The small flange 8 has an outer diameter D2 larger than the inscribed circle diameter D1 of the small diameter end of the multiple tapered rollers 6. The outer diameter D2 of the small flange 8 is the outer diameter at the point where the outer diameter of the small flange 8 is the largest, and in this case, the outer diameter D2 is the outer diameter at the apex position of the R surface 23 of the small flange 8. Here, when the dimensional relationship between the outer diameter D2 of the small flange 8 and the inscribed circle diameter D1 of the small diameter end of the tapered roller 6 is set to satisfy 0.005 < K < 0.040 when the small flange coefficient K = (D2 - D1) / 2 / D2, it is possible to effectively prevent the inner ring 5, tapered rollers 6, and cage 7 from coming apart while suppressing the elastic deformation of the cage 7 required for the tapered rollers 6 to get over the small flange 8.

The small diameter annular portion 13 is formed so that, when the center position of the retainer 7 and the center position of the inner ring 5 are aligned, the distance s between the inner circumferential surface 21 and the outer circumferential surface 20 of the small flange 8 at the position where the distance between the inner circumferential surface 21 and the outer circumferential surface 20 of the small flange 8 is at its narrowest, is in the range of 0.2 mm to 1.5 mm (preferably 0.2 mm to 1.0 mm, more preferably 0.2 mm to 0.7 mm). Here, the retainer 7 accommodates the tapered rollers 6 in the center position of the pocket 15 (the position where the amount of axial play of the retainer 7 is equal on one side and the other side in the axial direction). In addition, the distance s between the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8 can be set so that the distance between the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8 when the center position of the cage 7 is most eccentric with respect to the center position of the inner ring 5 is greater than zero and is 0.1 mm or less, by the amount of the clearance between the pocket 15 of the cage 7 and the tapered roller 6.

The end of the outer peripheral surface 20 farther from the small end face 10 of the tapered roller 6 is disposed closer to the small end face 10 of the tapered roller 6 than the end of the inner peripheral surface 21 of the small diameter side annular portion 13 farther from the small end face 10 of the tapered roller 6. In addition, an area equivalent to 80% or more of the axial length of the inner peripheral surface 21 of the small diameter side annular portion 13 faces the outer peripheral surface 20 of the small rib 8 in the radial direction. The outer diameter D3 at the smallest part of the outer peripheral surface 20 of the small rib 8 is set larger than the inscribed circle diameter D1 of the small diameter side end of the tapered roller 6.

The above tapered roller bearing 1 can be assembled as follows:

As shown in FIG. 3, first, the tapered rollers 6 are inserted into each pocket 15 of the cage 7. Next, as shown in FIG. 4 and FIG. 5, the inner ring 5 is inserted into the cage 7 with the tapered rollers 6 inserted into the pockets 15. This forms the inner ring assembly (the inner ring 5, tapered rollers 6, and cage 7 integrated together) as shown in FIG. 5. The inner ring assembly is then inserted into the outer ring 3 (see FIG. 1), completing the assembly of the tapered roller bearing 1. Here, as shown in FIG. 4, when the inner ring 5 is inserted into the cage 7 with the tapered rollers 6 inserted into the pockets 15, the tapered rollers 6 need to get over the small flange 8 of the inner ring 5, but the tapered rollers 6 are restricted from moving radially outward by the cage 7, so they cannot get over the small flange 8 with the dimensions remaining as they are.

Therefore, in order to make the tapered rollers 6 climb over the small flange 8, as shown in FIG. 4, when the tapered rollers 6 climb over the small flange 8, the force in the radial expansion direction that the tapered rollers 6 receive from the small flange 8 causes the retainer 7 to elastically deform, and the elastic deformation of the retainer 7 causes the tapered rollers 6 to climb over the small flange 8.

At this time, because the outer peripheral surface 20 of the small rib 8 of the inner ring 5 is tapered, it is possible to suppress the elastic deformation of the cage 7 that is necessary for the tapered rollers 6 to overcome the small rib 8, and it is possible to effectively prevent the cage 7 from being damaged by the stress caused by the elastic deformation. In addition, when the tapered rollers 6 are pressed against the small rib 8 by the elastic restoring force of the cage 7, the tapered rollers 6 and the small rib 8 come into contact over a relatively wide area, making it possible to prevent the tapered rollers 6 from being damaged by the force they receive from the small rib 8.

Figure 11 shows a view of the vicinity of the tapered roller bearing 1 when the tapered roller bearing 1 is installed and used in an automobile transmission 30.

The tapered roller bearing 1 is lubricated by splashing the lubricating oil stored in the housing 31 with a ring gear (not shown) so that the lubricating oil droplets splash onto the tapered roller bearing 1 (splash method), or by pumping the lubricating oil from an engine-driven oil pump (not shown) and injecting the lubricating oil into the housing 31 from a nozzle (not shown), which lubricates the tapered roller bearing 1 (pressure-fed lubrication method). It is also possible to lubricate the tapered roller bearing 1 by using the tapered roller bearing 1 with part of it immersed in the lubricating oil stored in the housing 31 (oil bath lubrication method).

Here, if the amount of lubricating oil flowing from the outside to the inside of the tapered roller bearing 1 is large, the agitation resistance of the lubricating oil inside the bearing increases the rotational torque required to rotate the tapered roller bearing 1. That is, as shown in FIG. 1, in the tapered roller bearing 1, the rotation radius of the tapered roller 6 when the bearing rotates is different between the small end face 10 side and the large end face 11 side of the tapered roller 6, so a pumping action is generated that moves the lubricating oil from the small end face 10 side to the large end face 11 side of the tapered roller 6, and this pumping action causes the phenomenon that the lubricating oil present outside the bearing is drawn into the inside of the bearing. And if the amount of lubricating oil drawn from the outside of the bearing to the inside of the bearing is large, the agitation resistance of the lubricating oil inside the bearing increases, resulting in the problem of the rotational torque required to rotate the tapered roller bearing 1 increasing.

Furthermore, in recent years, regulations on fuel efficiency for automobiles have become increasingly strict, and as a result, there is a growing demand for further reduction in rotational torque for parts used in automobile transmissions and differential mechanisms. In particular, as shown in FIG. 1, tapered roller bearings 1 have tapered rollers 6 as rolling elements that roll on inner ring raceway surface 4 while in sliding contact with large flange 9 of inner ring 5, so they tend to have a larger rotational torque than ball bearings that use balls as rolling elements, and there is a growing need to reduce the rotational torque of tapered roller bearings 1.

In response to this problem, in the tapered roller bearing 1 of this embodiment, as shown in FIG. 1, the small diameter side annular portion 13 of the retainer 7 is formed into an inward flange shape that extends radially inward from the axial end of the column portion 14 intersecting with the pitch cone P, and the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8 face each other and are inclined in the same direction, so that the axial end of the space between the column portion 14 and the inner ring raceway surface 4 is blocked by the small diameter side annular portion 13 of the retainer 7 and the small flange 8 of the inner ring 5, and the radial width of the flange-shaped small diameter side annular portion 13 can be made wide, making it difficult for lubricating oil to flow into the inside of the bearing. Therefore, the amount of lubricating oil that flows into the inside of the bearing due to the pump action during bearing rotation can be reduced, and the rotational torque due to the agitation resistance of the lubricating oil inside the bearing can be kept low.

As shown in FIG. 1, the tapered roller bearing 1 has an inclination angle θ3 of the inner peripheral surface 21 of the small diameter side annular portion 13 set to be equal to or within 5° (preferably within 3°, more preferably within 2°) of the inclination angle θ1 of the outer peripheral surface 20 of the small flange 8, so that the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8 are approximately parallel, making it possible to more effectively narrow the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8. As a result, it is possible to effectively prevent lubricating oil outside the bearing from flowing into the inside of the bearing through the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8, and to keep the rotational torque due to the stirring resistance of the lubricating oil inside the bearing low.

In addition, as shown in FIG. 2, the tapered roller bearing 1 has a distance s between the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8 set to 1.5 mm or less (preferably 1.0 mm or less, more preferably 0.7 mm or less), which effectively prevents lubricating oil outside the bearing from flowing into the bearing through the gap between the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8.

In addition, this tapered roller bearing 1 adopts a configuration in which the end of the outer peripheral surface 20 of the small flange 8 farther from the small end face 10 of the tapered roller 6 is closer to the small end face 10 of the tapered roller 6 than the end of the inner peripheral surface 21 of the small diameter side annular portion 13 farther from the small end face 10 of the tapered roller 6, so that the end of the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8 farther from the small end face 10 of the tapered roller 6 is covered from the radial outside by the small diameter side annular portion 13. Therefore, lubricating oil outside the bearing is less likely to enter the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8, and it is possible to effectively suppress the lubricating oil outside the bearing from flowing into the inside of the bearing through the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8.

In addition, as shown in FIG. 2, in this tapered roller bearing 1, the outer diameter D2 of the small flange 8 is larger than the inscribed circle diameter D1 of the small diameter end of the tapered roller 6, so it is possible to effectively prevent the inner ring 5 from coming out of the cage 7 and the inner ring 5, tapered roller 6, and cage 7 from coming apart.

As shown in Figure 1, the tapered roller bearing 1 has an inclination angle θ1 of the outer peripheral surface 20 of the small flange 8 set to be the same as the inclination angle θ2 of the inner ring raceway surface 4 or set to a value within 5° (preferably within 3°, more preferably within 2°), so that when assembling the tapered roller bearing 1 as shown in Figures 3 to 5, the outer peripheral surface 20 of the small flange 8 comes into contact with the tapered roller 6 over its entire axial length, as shown by the dotted line in Figure 3. This makes it possible to effectively prevent the tapered roller 6 from being damaged by the force received from the small flange 8.

In addition, as shown in FIG. 2, the small rib surface 22 of the small rib 8 of this tapered roller bearing 1 is smoothly connected to the outer peripheral surface 20 by an R surface 23 having an arc-shaped cross section, so that it is possible to effectively prevent the tapered rollers 6 from being damaged when they ride over the small rib 8.

In addition, this tapered roller bearing 1 uses a resin material with an elastomer added as the resin composition forming the cage 7, so the cage 7 is highly flexible. This makes it easy to insert tapered rollers 6 into each pocket 15 of the cage 7 and then attach them to the outer periphery of the inner ring 5, making the tapered roller bearing 1 easy to assemble. In other words, by making the small-diameter annular portion 13 of the cage 7 an inward flange shape that extends radially inward, it is possible to ensure the effect of reducing the stirring torque of the lubricating oil inside the bearing while also ensuring the ease of assembly of the tapered roller bearing 1.

In addition, in this tapered roller bearing 1, fiber reinforcement is added to the resin composition that forms the cage 7 in addition to the elastomer, so the reduction in strength of the cage 7 caused by adding the elastomer can be compensated for by the fiber reinforcement. This makes it possible to achieve both ease of assembly of the tapered roller bearing 1 and strength of the cage 7.

As shown in FIG. 6, it is sufficient that at least a portion of the inner circumferential surface 21 of the small diameter side annular portion 13 faces the outer circumferential surface 20 of the small flange 8 in the radial direction. However, as in the above embodiment, if an area corresponding to 80% or more of the axial length of the inner circumferential surface 21 (conical surface) of the small diameter side annular portion 13 faces the outer circumferential surface 20 of the small flange 8 in the radial direction, the axial length of the gap between the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8 can be increased, which is preferable because it can prevent lubricating oil outside the bearing from flowing into the inside of the bearing through the gap between the inner circumferential surface 21 of the small diameter side annular portion 13 and the outer circumferential surface 20 of the small flange 8.

As shown in FIG. 7, the axial length of the outer peripheral surface 20 of the small flange 8 may be set to be greater than the axial length of the inner peripheral surface 21 of the small diameter side annular portion 13, and the entire surface of the inner peripheral surface 21 may be made to face the outer peripheral surface 20 in the radial direction. In this way, the entire surface of the inner peripheral surface 21 of the small diameter side annular portion 13 of the retainer 7 faces the outer peripheral surface 20 of the small flange 8 to form a labyrinth gap, thereby obtaining the effect of suppressing the flow of lubricating oil from outside the bearing into the inside of the bearing. In this case, the outer diameter D3 at the portion where the outer diameter of the outer peripheral surface 20 of the small flange 8 is smallest can be set to the same size as the inscribed circle diameter D1 of the small diameter side end of the tapered roller 6.

As shown in FIG. 8, the axial width of the small flange 8 may be further increased. In this case, the outer diameter D3 at the smallest point of the outer peripheral surface 20 of the small flange 8 is set to the same size as the inscribed circle diameter D1 of the small diameter end of the tapered roller 6, and a straight second outer peripheral surface 24 can be further provided that extends axially from the small diameter end of the outer peripheral surface 20 with a constant outer diameter.

As shown in FIG. 9, it is possible to make the axial thickness of the small diameter side annular portion 13 thin, but as in the above embodiment, by adopting a small diameter side annular portion 13 having an axial thickness equivalent to 90% or more of the axial length of the tapered outer peripheral surface 20 (conical surface) of the small flange 8, the axial length of the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8 can be increased, which is preferable because it can prevent lubricating oil outside the bearing from flowing into the inside of the bearing through the gap between the inner peripheral surface 21 of the small diameter side annular portion 13 and the outer peripheral surface 20 of the small flange 8.

As shown in FIG. 10, a circumferentially extending steal groove 25 may be provided on the axial side of the small diameter annular portion 13. In this way, the amount of resin composition constituting the retainer 7 can be reduced, resulting in lower costs.

The tapered roller bearing 1 can also be used as a rolling bearing that rotatably supports the input shaft 41 of the differential mechanism 40 shown in FIG. 12. FIG. 12 shows a view of the tapered roller bearing 1 and its surroundings when the tapered roller bearing 1 is incorporated into a differential mechanism.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1 Tapered roller bearing 2 Outer ring raceway surface 3 Outer ring 4 Inner ring raceway surface 5 Inner ring 6 Tapered roller 7 Cage 8 Small rib 9 Large rib 10 Small end face 11 Large end face 12 Large diameter side annular portion 13 Small diameter side annular portion 14 Column portion 20 Outer peripheral surface 21 Inner peripheral surface 22 Small rib surface 23 R surface D1 Inscribed circle diameter D2 Outer diameter P Pitch cone s Distances θ1, θ2, θ3 Inclination angle

Claims (9)

An outer ring (3) having a conical outer ring raceway surface (2) on its inner circumference;
An inner ring (5) is disposed coaxially inside the outer ring (3) and has a conical inner ring raceway surface (4) on its outer periphery;
a plurality of tapered rollers (6) assembled at intervals in the circumferential direction between the outer ring raceway surface (2) and the inner ring raceway surface (4);
and an annular cage (7) that maintains the circumferential spacing of the plurality of tapered rollers (6),
A large rib (9) that contacts the large end face (11) of each of the tapered rollers (6) and a small rib (8) that faces the small end face (10) of each of the tapered rollers (6) in the axial direction are provided on the outer periphery of the inner ring (5),
The retainer (7) is a tapered roller bearing having a large diameter side annular portion (12) extending in the circumferential direction along the large end faces (11) of the plurality of tapered rollers (6), a small diameter side annular portion (13) extending in the circumferential direction along the small end faces (10) of the plurality of tapered rollers (6), and a plurality of pillar portions (14) connecting the large diameter side annular portion (12) and the small diameter side annular portion (13),
the large diameter side annular portion (12), the small diameter side annular portion (13), and the plurality of pillar portions (14) are integrally formed from a resin composition,
the plurality of column portions (14) are arranged such that the entirety of each column portion (14) is located radially outward of a pitch cone (P) formed by a locus of centers of tapered roller angles when the plurality of tapered rollers (6) revolve,
The small diameter side annular portion (13) has an inward flange shape extending radially inward from an axial end portion of the column portion (14) and intersecting with the pitch cone (P),
The small flange (8) has a tapered outer circumferential surface (20) that gradually becomes larger in diameter as it approaches the small end surface (10) of the tapered roller (6),
the small diameter side annular portion (13) has an inner peripheral surface (21) facing the outer peripheral surface (20) of the small flange (8), and the inner peripheral surface (21) is formed in a tapered shape that gradually becomes larger in diameter as it approaches the small end surface (10) of the tapered roller (6);
the inclination angle (θ1) of the outer peripheral surface (20) of the small flange (8) is set to be equal to or the difference between the inclination angle (θ2) of the inner ring raceway surface (4) is within 2°;
the small rib (8) further having an R surface (23) having an arc-shaped cross section with a radius (r) of 1.5 mm or more and 3.0 mm or less , which smoothly connects to the outer peripheral surface (20) of the small rib (8), and a small rib surface (22) formed and connected to the R surface (23) and facing a small end surface (10) of the tapered roller (6). A tapered roller bearing according to claim 1, in which the outer diameter (D2) at the largest part of the small flange (8) is larger than the inscribed circle diameter (D1) of the small diameter end of the plurality of tapered rollers (6). A tapered roller bearing according to claim 1 or 2, in which the inclination angle (θ3) of the inner peripheral surface (21) of the small diameter side annular portion (13) is set to be equal to or within 5° of the inclination angle (θ1) of the outer peripheral surface (20) of the small flange (8). A tapered roller bearing according to any one of claims 1 to 3, wherein the small diameter side annular portion (13) is formed so that the distance (s) between the inner peripheral surface (21) and the outer peripheral surface (20) of the small flange (8) is 1.5 mm or less. A tapered roller bearing according to any one of claims 1 to 4, in which the end of the outer circumferential surface (20) farther from the small end face (10) of the tapered roller (6) is disposed closer to the small end face (10) of the tapered roller (6) than the end of the inner circumferential surface (21) farther from the small end face (10) of the tapered roller (6). 5. A tapered roller bearing according to claim 1, wherein an axial length of the outer circumferential surface (20) is set to be greater than an axial length of the inner circumferential surface (21), and the entire surface of the inner circumferential surface (21) faces the outer circumferential surface (20). A tapered roller bearing according to any one of claims 1 to 6, wherein the resin composition is a resin material to which an elastomer has been added. A tapered roller bearing as described in claim 7, in which a fiber reinforcing material is further added to the resin material. A tapered roller bearing according to claim 7 or 8, wherein the resin material is polyamide or polyphenylene sulfide.

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