JP7351141B2 - tapered roller bearing - Google Patents

Description

The present invention relates to a tapered roller bearing, and particularly to a tapered roller bearing in which lubricating oil is supplied inside the bearing.

In recent years, mechanisms have been introduced that stop the lubricating oil pump when the engine is stopped, such as in the transmissions of some hybrid vehicles, which can easily cause the problem of bearing seizure. Furthermore, when the vehicle is being towed, the lubricating oil pump does not operate and the tires spin, which may cause seizing of the bearings in the transmission. Therefore, there is a need for a bearing that can prevent seizure even under a lubricating environment where the supply of lubricating oil is intermittent or under a lubricating environment where the lubricating oil is in a small amount.

As shown in FIGS. 23 to 26, a conventional tapered roller bearing 100 includes an outer ring 111 having an outer ring raceway surface 111a on its inner peripheral surface, an inner ring 112 having an inner ring raceway surface 112a on its outer peripheral surface, and an outer ring raceway surface 111a on its outer peripheral surface. It is known that the bearing includes a plurality of tapered rollers 113 that are rotatably provided between the inner ring raceway surface 112a and a cage 114 that holds the plurality of tapered rollers 113 at approximately equal intervals in the circumferential direction ( For example, see Patent Document 1).

The retainer 114 also includes a large-diameter annular portion 115 , a small-diameter annular portion 116 coaxially arranged with the large-diameter annular portion 115 , and a large-diameter annular portion 115 and a small-diameter annular portion 116 . A large diameter annular portion 115 and a small diameter annular portion 116 are connected to each other in the axial direction and are provided at approximately equal intervals in the circumferential direction. The pocket 118 is surrounded by a pocket 118 and holds the tapered roller 113 in a rollable manner. Further, the tapered rollers 113 have a rolling surface 113a provided on the circumferential surface of the tapered rollers 113, a large diameter end surface 113b provided on the large diameter end of the tapered rollers 113, and a small diameter end of the tapered rollers 113. It has a small diameter side end surface 113c provided.

Patent No. 6354242

In the tapered roller bearing 100 described in Patent Document 1, one oil groove 120 along the circumferential direction is formed in the axially inner end surface 115a of the large-diameter side annular portion 115 of the cage 114, and the oil groove 120 is formed along the circumferential direction. In order to increase the amount of lubricating oil stored inside the groove 120, the radial width of the oil groove 120 is set to 1/3 of the radial width of the large diameter annular portion 115. That is, for example, when the radial width of the large-diameter side annular portion 115 is 9 mm, the radial width of the oil groove 120 is 3 mm. In this case, since the oil groove 120 alone cannot generate capillary action and retain lubricating oil, it is necessary to cover the oil groove 120 with tapered rollers 113 as described in Patent Document 1 mentioned above. there were.

However, as shown in FIG. 23, when the cage 114 moves axially toward the larger diameter side of the tapered rollers 113, the larger diameter end surface 113b of the tapered roller 113 and the axial inner end surface of the larger diameter annular portion 115 115a becomes large, and the lubricating oil leaks out from the oil groove 120 without capillary action. Therefore, in Patent Document 1, it is necessary to make the axial gap between the tapered rollers 113 and the cage 114 extremely small. It was difficult to incorporate into

Furthermore, in the drawings of Patent Document 1, the large-diameter side end surfaces of the tapered rollers are shown as planar, but as shown in FIGS. 23 to 25, the large-diameter side end surfaces 113b of the tapered rollers 113 have a convex spherical shape. In some cases, a concave portion 113d is formed in the center of the large-diameter end surface 113b. In such a tapered roller 113, even if the axial gap between the tapered roller 113 and the cage 114 is made small, the gap SP (Fig. 26 Lubricant oil was leaking from the

The present invention has been made in view of the above-mentioned problems, and its purpose is to be able to hold lubricating oil in a single oil groove, and to be used in a lubricating environment where the supply of lubricating oil is intermittent, or when lubricating oil is An object of the present invention is to provide a tapered roller bearing that can prevent seizure even under a lubricated environment with a small amount of oil.

The above object of the present invention is achieved by the following configuration.
(1) An outer ring having an outer ring raceway surface on its inner peripheral surface, an inner ring having an inner ring raceway surface on its outer peripheral surface, and a plurality of tapered rollers that are rotatably provided between the outer ring raceway surface and the inner ring raceway surface. , a cage that holds the plurality of tapered rollers at substantially equal intervals in the circumferential direction, and the cage includes a large diameter annular portion and a small diameter annular portion disposed coaxially with the large diameter annular portion. a side annular portion, a plurality of column portions that connect the large diameter side annular portion and the small diameter side annular portion in the axial direction and are provided at approximately equal intervals in the circumferential direction; A tapered roller bearing having a pocket formed between column parts and holding the tapered roller in a rollable manner, wherein the cage is arranged between an axially inner end surface of the small-diameter side annular part and the tapered roller. a first gap between the small diameter side end face and a second gap between the axially inner end face of the large diameter side annular portion and the large diameter side end face of the tapered roller; A plurality of oil grooves for retaining lubricating oil by capillary force are provided on the axially inner end surface of the large-diameter side annular portion, and the retainer is movable within a predetermined range along the tapered roller. When the retainer moves axially toward the small diameter side of the tapered roller, the plurality of oil grooves come into contact with the large diameter end surface of the tapered roller, and when the cage moves axially toward the large diameter side of the tapered roller, A tapered roller bearing, wherein the plurality of oil grooves are spaced apart from a large-diameter end face of the tapered roller.
(2) The tapered roller bearing according to (1), wherein the plurality of oil grooves are formed in parallel along the circumferential direction of the cage.
(3) The plurality of oil grooves each have a groove end that can come into contact with the large-diameter end surface of the tapered roller, and the large-diameter end surface of the tapered roller is formed at the center of the large-diameter end surface. a circular recessed portion; and an annular contact surface provided around the recessed portion and capable of contacting the axially inner end surface of the large-diameter side annular portion; According to (2), the groove end portion is provided in a region where the annular contact surface and the axially inner end surface of the large diameter annular portion overlap in the longitudinal direction of the tapered roller. Tapered roller bearings listed.
(4) The axially inner end surface of the large diameter annular portion is formed in a concave spherical shape, and the large diameter end surface of the tapered roller is formed in a convex spherical shape, and the axially inner end surface of the large diameter annular portion is formed in a convex spherical shape. The tapered roller bearing according to (1), wherein the radius of curvature SRy of the concave spherical end face is set within ±10% of the radius of curvature Ra of the convex spherical end face of the large diameter side of the tapered roller. .
(5) The plurality of oil grooves are each formed in an annular fan shape, and a pair of end connecting sides, which are both end sides in the longitudinal direction of the plurality of oil grooves, are each provided so as to be aligned with a pair of straight lines, and the The tapered roller bearing according to item (2), wherein the pair of straight lines are inclined lines such that the circumferential distance between them increases as the line goes radially inward of the large-diameter side annular portion.
(6) The tapered roller bearing according to (2), wherein the plurality of adjacent oil grooves are connected to each other by at least one connecting groove.
(7) Any one of (1) to (6) characterized in that the bearing is used under a lubrication environment in which lubricating oil is intermittently supplied inside the bearing or in which the lubricating oil inside the bearing is in a small amount. Tapered roller bearings listed in .

According to the present invention, a plurality of oil grooves that retain lubricating oil by capillary force are provided on the axially inner end surface of the large-diameter annular portion of the cage, so there is no need to cover the oil grooves with tapered rollers. Also, the oil groove alone can hold lubricating oil. In addition, when the cage moves axially to the small diameter side of the tapered rollers, the oil grooves come into contact with the large diameter side end face of the tapered rollers, so it is difficult to operate under a lubrication environment where the supply of lubricating oil is intermittent, or when the lubrication oil is intermittently supplied. Even in a lubricated environment with a small amount of oil, seizure of the bearing can be prevented. In addition, when the cage moves axially toward the large diameter side of the tapered rollers, the oil groove moves away from the large diameter side end face of the tapered rollers, and the large diameter side ring part does not constantly contact the tapered rollers. It is possible to suppress an increase in frictional resistance during rotation, and further, it is possible to suppress wear of the large-diameter side annular portion. Furthermore, there is no need for sophisticated management of component dimensional accuracy, and an increase in manufacturing costs can be suppressed.

FIG. 1 is a sectional view illustrating an embodiment of a tapered roller bearing according to the present invention. FIG. 3 is a plan view of the cage and tapered rollers viewed from the outside in the radial direction. FIG. 2 is a schematic diagram of the retainer shown in FIG. 1 viewed from the inside in the radial direction. FIG. 3 is a schematic diagram showing a contact positional relationship between a circumferential groove end of an oil groove and a large-diameter end surface of a tapered roller. FIG. 2 is a cross-sectional view illustrating a case where the cage shown in FIG. 1 is moved in the axial direction toward the larger diameter side of the tapered rollers. FIG. 2 is a cross-sectional view illustrating a case where the cage shown in FIG. 1 is moved in the axial direction toward the small diameter side of the tapered rollers. FIG. 3 is an explanatory diagram showing a state in which a groove end is in contact with a tapered roller. It is an explanatory view showing a state where a groove end does not contact a tapered roller. FIG. 3 is an explanatory diagram showing a case where the corners of the oil groove are formed with sharp edges. It is an explanatory view showing the case where the corner of the oil groove is formed in a large circular arc shape. FIG. 3 is an explanatory diagram showing a case where the depth of the oil groove is decreased from the center of the oil groove toward the end of the groove. It is an explanatory view showing a case where the depth of the oil groove is made uniform from the groove center part to the groove end part of the oil groove. FIG. 2 is a schematic diagram illustrating that the radius of the arc shape at the groove bottom corner of the radial cross section of the oil groove is made smaller from the center of the oil groove toward the groove end. FIG. 3 is a schematic diagram illustrating a first example in which the radial width of the oil groove is reduced at both ends in the longitudinal direction. FIG. 7 is a schematic diagram illustrating a second example in which the radial width of the oil groove is reduced at both ends in the longitudinal direction. FIG. 7 is a schematic diagram illustrating a third example in which the radial width of the oil groove is reduced at both ends in the longitudinal direction. FIG. 7 is a schematic diagram illustrating a fourth example in which the radial width of the oil groove is reduced at both ends in the longitudinal direction. FIG. 3 is a schematic diagram illustrating a first example in which the radial width of the oil groove is reduced from the groove center toward the groove end. FIG. 7 is a schematic diagram illustrating a second example in which the radial width of the oil groove decreases from the groove center toward the groove end. It is a schematic diagram explaining the 1st modification of a cage. It is a schematic diagram explaining the 2nd modification of a cage. It is a schematic diagram explaining the 3rd modification of a cage. FIG. 7 is a plan view of a third modification of the retainer viewed from the outside in the radial direction. FIG. 3 is a cross-sectional view illustrating oil supply to a bearing by a lubricating oil pump. FIG. 3 is a cross-sectional view illustrating oil supply to a bearing by splashing a gear. FIG. 3 is a cross-sectional view illustrating a conventional tapered roller bearing in which the retainer moves in the axial direction toward the larger diameter side of the tapered rollers. FIG. 24 is a cross-sectional view illustrating a case where the cage shown in FIG. 23 is moved in the axial direction toward the small diameter side of the tapered rollers. FIG. 24 is a plan view of the cage and tapered rollers shown in FIG. 23 viewed from the outside in the radial direction. FIG. 24 is a schematic diagram showing the contact positional relationship between the oil groove shown in FIG. 23 and the large-diameter end surface of the tapered roller.

Hereinafter, one embodiment of a tapered roller bearing according to the present invention will be described in detail based on the drawings.

As shown in FIG. 1, the tapered roller bearing 10 of this embodiment includes an outer ring 11 having an outer ring raceway surface 11a on its inner peripheral surface, an inner ring 12 having an inner ring raceway surface 12a on its outer peripheral surface, an outer ring raceway surface 11a and an inner ring. It includes a plurality of tapered rollers 13 that are rotatably provided between the raceway surface 12a and a cage 14 that holds the plurality of tapered rollers 13 at approximately equal intervals in the circumferential direction. In this embodiment, the lubricating oil circulating inside the housing H (see FIG. 21) is appropriately supplied to the inside of the bearing by a lubricating oil pump P (see FIG. 21) or the like.

The inner ring 12 has a large flange 12 b provided at the large diameter end of the inner ring 12 and a small flange 12 c provided at the small diameter end of the inner ring 12 . The outer peripheral surface of the inner ring 12 is formed into a substantially conical shape.

The tapered rollers 13 are provided with rolling surfaces 13a provided on the circumferential surface of the tapered rollers 13, large diameter end surfaces 13b provided on the large diameter side ends of the tapered rollers 13, and provided on small diameter side ends of the tapered rollers 13. It has a small diameter side end surface 13c. Further, the large-diameter side end surface 13b is formed in a convex spherical shape with a radius of curvature Ra, and a circular recess 13d is formed in the center thereof. The center of the convex spherical surface is located on the rotation axis of the tapered rollers 13.

The cage 14 is made of synthetic resin and is injection molded by axial draw, and includes a large diameter annular portion 15, a small diameter annular portion 16 coaxially arranged with the large diameter annular portion 15, and a large diameter annular portion 16. The diameter side annular part 15 and the small diameter side annular part 16 are connected in the axial direction, and a plurality of pillar parts 17 provided at approximately equal intervals in the circumferential direction and between the pillar parts 17 adjacent to each other in the circumferential direction are connected to each other in the axial direction. It has a pocket 18 that is surrounded by the diameter side annular portion 15 and the small diameter side annular portion 16 and holds the tapered roller 13 in a rollable manner.

Further, the cage 14 has a first gap S1 between the axially inner end surface 16a of the small-diameter side annular portion 16 of the cage 14 and the small-diameter side end surface 13c of the tapered rollers 13. Further, the cage 14 has a second gap S2 between the axially inner end surface 15a of the large-diameter side annular portion 15 of the cage 14 and the large-diameter side end surface 13b of the tapered rollers 13. Thereby, the retainer 14 is provided so as to be movable within a predetermined range along the axial direction. In addition, in FIG. 1, the tapered rollers 13 and the cage 14 are shown in a state located in the middle in the axial direction with respect to the outer ring 11.

In the tapered roller bearing 10 of this embodiment, as shown in FIG. LR, the length of the pocket 18 of the retainer 14 in the roller axial direction is LP, and the total dimension of the entire gap in the roller axial direction is Dt, the relationship is Dt=D1+D2=LP-LR. Note that the roller axial dimensions D1 and D2, the length LR of the tapered roller 13, and the roller axial length LP of the pocket 18 are dimensions along the central axis (rotation axis) direction of the tapered roller 13. .

In this way, since an axial gap is provided between the tapered rollers 13 and the cage 14, the cage 14 can freely move along the axial direction within the range of the total gap dimension Dt. In addition, in this embodiment, the roller axial dimension D1 of the first gap S1 and the roller axial dimension D2 of the second gap S2 do not require strict dimensional control, and are taken into account in consideration of the general machining accuracy of the cage. , is set to 0.05 mm or more, which is a general gap size.

Further, the surface of the axially inner end surface (hereinafter also simply referred to as "pocket surface") 15a of the large-diameter side annular portion 15 of the retainer 14 is formed to be rough, and the surface roughness of the specific pocket surface 15a is rough. (Arithmetic mean roughness) is set to 3 μm to 20 μm.

The roughness of the pocket surface 15a of the large-diameter annular portion 15 functions to guide lubricating oil stored in oil grooves 20, which will be described later, to the tapered rollers 13. Thereby, the oil retention ability and oil supply ability of the pocket surface 15a can be improved. Further, it is preferable that the inner surface of the oil groove 20, which will be described later, is also formed roughly to improve the oil retaining ability. Furthermore, since the pocket surface 15a is substantially perpendicular to the direction of mold removal during molding of the cage, even if the pocket surface 15a is formed roughly, it will not be a problem during mold release after molding. Note that the surface roughness of the pocket surface 15a may be set for all pockets 18 or for some pockets 18.

The pocket surface 15a of the large diameter annular portion 15 is formed into a concave spherical shape with a radius of curvature SRy. The radius of curvature SRy of the concave spherical surface of the pocket surface 15a is set within ±10% of the radius of curvature Ra of the convex spherical surface of the large diameter end surface 13b of the tapered roller 13 (0.9Ra≦SRy≦1 .1Ra). This improves the degree of close contact between the pocket surface 15a and the large-diameter end surface 13b of the tapered roller 13, so that high oil retention and oil supply effects can be obtained. However, if SRy is made to match Ra (SRy=Ra) and the entire surface contacts, the frictional resistance will increase, so it is best to slightly shift the radius of curvature so that complete contact is not achieved.

Further, as shown in FIGS. 1 to 4, a plurality (two in this embodiment) of fine oil grooves 20 are formed in the pocket surface 15a of the large-diameter annular portion 15 of the retainer 14. . The two oil grooves 20 are bottomed grooves, and are formed in parallel along the circumferential direction of the retainer 14 in each pocket 18 . The oil groove 20 is a groove capable of retaining lubricating oil by capillary force, and enhances the oil retaining ability of the retainer 14 and promotes the propagation of the lubricating oil to the tapered rollers 13. Note that the oil groove 20 may be provided for all pockets 18 or for some pockets 18. Note that the number of oil grooves 20 may be two or more, and the number of installed oil grooves 20 is arbitrary.

FIG. 4 is a schematic diagram showing the contact positional relationship between the circumferential groove end 20a of the oil groove 20 and the large-diameter end surface 13b of the tapered roller 13. The large-diameter end surface 13b of the tapered roller 13 includes a circular recess 13d formed at the center of the large-diameter end surface 13b, and an annular contact surface provided around the recess 13d and capable of contacting the pocket surface 15a. 13e. The groove ends 20a of each of the two oil grooves 20 are located in a region where the annular contact surface 13e and the pocket surface 15a overlap in the longitudinal direction of the tapered roller 13 (an area where the annular contact surface 13e and the pocket surface 15a overlap when viewed in the longitudinal direction of the tapered roller 13). ). This makes it possible to supply lubricating oil to the tapered rollers 13 by capillary force with the tapered rollers 13 without leaving any of the lubricating oil collected at the groove ends 20a by a mechanism described later with reference to FIGS. 7 to 9. Note that the symbol L in FIGS. 4 and 7 to 9 indicates lubricating oil (the part provided with a dot pattern).

Further, as shown in FIG. 4, in this embodiment, the two oil grooves 20 are each formed in an annular fan shape, and a pair of end connecting sides 21, which are both ends in the longitudinal direction of the two oil grooves 20, are formed in an annular fan shape. , are provided so as to be aligned with a pair of straight lines 21L. The pair of straight lines 21L are inclined lines such that the distance between them in the circumferential direction increases toward the inside of the large-diameter annular portion 15 in the radial direction. Thereby, the processing of the molding die can be facilitated, and the respective groove ends 20a of the two oil grooves 20 can be easily arranged within the annular contact surface 13e of the tapered roller 13.

Here, the capillary force mentioned in this explanation is the force by which a solid tries to attract a liquid. Capillary force occurs when the surface tension of the solid (retainer) is greater than the surface tension of the liquid (lubricating oil), and the liquid is attracted to the solid surface. Liquids also tend to reduce the surface area that comes into contact with air due to surface tension. In other words, the lubricating oil attempts to increase the area in contact with the cage while decreasing the area in contact with air. Therefore, the capillary force increases as the oil groove of the retainer becomes thinner (the radial width dimension of the oil groove 20 is smaller). Utilizing this principle, in the present invention, a thin oil groove 20 is formed in the pocket surface 15a. The oil groove 20 is characterized in that lubricating oil is supplied from the groove end 20a connected to the pocket surface 15a of the large-diameter annular portion 15 to the large-diameter end surface 13b of the tapered roller 13. Note that the groove end portion 20a is an end portion of the oil groove 20 in the circumferential direction (longitudinal direction). Further, the groove center portion 20b, which will be described later, refers to the center portion of the oil groove 20 in the circumferential direction (longitudinal direction).

In addition, the oil groove 20 needs to have a fine shape that allows oil retention and oil supply to the tapered rollers 13 by the action of capillary force, and in this embodiment, the radial width and depth of the oil groove 20 are (Axial width) is set to be constant or so that the groove end 20a becomes shallow (axial width becomes small), and is determined by the lubricating oil retention of the oil groove 20, the strength of the retainer 14, and general injection molding. In consideration of the accuracy, for example, the radial width D3 of the oil groove 20 is set to 0.5 mm or less at the maximum part, and more preferably to 0.2 mm or less. The depth D4 of the oil groove 20 is set in a range from 0.05 mm at the maximum part to 1/5 or less of the length LR of the tapered roller 13. Note that the radial width D3 of the oil groove 20 is the width in the direction orthogonal to the extending direction of the oil groove 20. Further, the oil groove 20 formed by axial draw extends in the same direction (axial direction) as the central axis of the retainer 14, which is the direction in which the mold moves (releases the mold) during injection molding.

The cage 14 is made of synthetic resin, and can be injection molded by, for example, axial draw. The surface roughness of the pocket surface 15a of the large-diameter annular portion 15 and the oil groove 20 can also be formed at the same time by this injection molding. In this case, there is no need for additional processing steps, special molding such as two-color molding (double molding), or adhesion of a separately manufactured oil retaining member. Therefore, seizure resistance can be improved without substantially increasing manufacturing costs.

The material for the retainer 14 is not particularly limited, but may be any synthetic resin material that has a high surface tension and lipophilicity that generates capillary force with respect to the lubricating oil used; for example, a general material such as nylon. Examples of cage resin materials include: Note that the synthetic resin of the cage 14 may contain fibers as a reinforcing agent. It is also possible to use a resin material with low lipophilicity, but in this case it is preferable to perform lipophilic treatment.

7A and 7B are explanatory diagrams showing the positional relationship between the longitudinal direction (circumferential direction) of the oil groove 20 and the tapered rollers 13, in which one oil groove 20 portion of the cage 14 is cut along the circumferential direction. FIG. The retainer 14 is characterized by supplying the lubricating oil stored inside the oil groove 20 by capillary force to the large-diameter side end surface 13b of the tapered roller 13 by the action of capillary force with the roller surface. In order to make this effect effective, it is important that the oil groove 20 generates a high capillary force at the portion where the tapered roller 13 and the pocket surface 15a are in contact. As one method for this, in this embodiment, as shown in FIG. 7A, the groove end portion 20a having a higher capillary force than the middle portion of the oil groove 20 is configured to contact the tapered roller 13. Thereby, the lubricating oil inside the oil groove 20 can be sucked up from the corner 20d of the groove end 20a by capillary force with the large-diameter end surface 13b of the tapered roller 13. In addition, in FIG. 7B, since the groove end portion 20a does not come into contact with the tapered roller 13, the amount of lubricating oil sucked up is reduced. Further, in FIGS. 7A and 7B, the depth of the oil groove 20 is shown enlarged from the actual depth in order to facilitate understanding of the explanation.

8A and 8B are explanatory diagrams showing the radial cross-sectional shape of the oil groove 20, and are cross-sectional views of one oil groove 20 of the retainer 14 cut along the radial direction. As is clear from the capillary phenomenon, the capillary force acts more strongly in a narrower space, so even if the radial width D3 of the oil groove 20 is narrow, it becomes weaker if the opening is widened as shown in FIG. 8B. Therefore, in this embodiment, as shown in FIG. 8A, a corner 20d connecting the wall surface of the oil groove 20 (at least one of the radial wall surface and the circumferential wall surface of the oil groove 20) 20c and the pocket surface 15a is It is formed into a sharp edge (an arc-shaped chamfer with a radius of 0.1 mm or less, preferably an arc-shaped chamfer with a radius of 0.05 mm or less, or a linear chamfer with a side of 0.1 mm and an angle of 45 degrees). By forming the corner portion 20d with a sharp edge, it becomes possible to easily guide lubricating oil to the pocket surface 15a. In addition, in FIG. 8B, since the arc of the corner 20d is large, the oil level of the lubricating oil does not reach the pocket surface 15a, and the amount of oil supplied is reduced.

Further, the groove bottom corner 20e of the radial cross section of the oil groove 20 is formed in an arc shape, and when the radius Rw of the arc shape of the groove bottom corner 20e is small, capillary force increases and lubricating oil flows into the groove bottom corner 20e. It acts to stay in place. Therefore, the radius Rw of the arc shape of the groove bottom corner 20e in the radial cross section of the oil groove 20 is 1 of the radial width D3 of the oil groove 20 at the groove center portion 20b, which is the longitudinal center of the oil groove 20, which is the maximum. It is preferable to set it between /4 and 1/2. In addition, in order to increase the capillary force to the groove end 20a, as shown in FIG. It is even more desirable to make it smaller toward the groove end 20a (Rw1>Rw2>Rw3). Thereby, the lubricating oil accumulated in the groove center portion 20b can be sucked up to the groove end portion 20a where the capillary force is higher and guided to the pocket surface 15a.

9A and 9B are explanatory diagrams showing the cross-sectional shape of the oil groove 20 in the longitudinal direction (circumferential direction), and are cross-sectional views of one oil groove 20 of the retainer 14 cut along the circumferential direction. . As shown in FIG. 9B, when the groove bottom corner 20f of the circumferential cross section of the oil groove 20 is close to a right angle, the lubricating oil remains at the groove bottom corner 20f, making it difficult to supply oil to the tapered rollers 13. For this reason, it is desirable to set the depth D4 of the groove end portion 20a to be smaller (shallower) than the depth D4 of the groove center portion 20b. Specifically, as shown in FIG. 9A, the groove bottom corner 20f of the circumferential cross section of the oil groove 20 is formed into an arc shape, and the depth D4 of the oil groove 20 is set from the groove center portion 20b of the oil groove 20. It becomes smaller toward the groove end 20a. Thereby, the capillary force of the portion of the groove end 20a connected to the pocket surface 15a can be increased, and the lubricating oil accumulated at the groove bottom can be efficiently sucked up and supplied to the tapered rollers 13. Note that in FIGS. 9A and 9B, the depth of the oil groove 20 is shown enlarged from the actual depth in order to facilitate understanding of the explanation.

11 to 14 are schematic diagrams illustrating an example in which the radial width D3 of the oil groove 20 is made smaller (thinner) at both ends in the longitudinal direction. That is, in the oil groove 20 shown in FIGS. 11 to 14, the radial width D3 of the groove end portion 20a is set smaller than the radial width D3 of the groove center portion 20b. By making the tip of the oil groove 20 thinner in this way, the capillary force at the groove end 20a can be increased, and the lubricating oil accumulated at the groove bottom can be efficiently sucked up and supplied to the tapered rollers 13. . In addition, since the narrowed part is limited to a portion of the tip, the shape makes it easy to store a large amount of lubricating oil without reducing the overall space volume of the groove.

The oil groove 20 shown in FIG. 11 has a shape (annular fan shape) in which a linear chamfer Cx is provided on one radial side of the longitudinal end of the oil groove 20. The oil groove 20 shown in FIG. 12 has a shape (approximately hexagonal shape) in which linear chamfers Cx are provided on both sides of the longitudinal end portion of the oil groove 20 in the radial direction. The oil groove 20 shown in FIG. 13 has a shape in which an arcuate chamfer Rx is applied to the longitudinal end of the annular fan-shaped oil groove 20 shown in FIG. The oil groove 20 shown in FIG. 14 has a shape in which a linear small chamfer Cxx is formed on the groove end 20a, which is the longitudinal end of the annular fan-shaped oil groove 20 shown in FIG. In addition, in the oil groove 20 shown in FIGS. 11 to 14, the depth D4 of the oil groove 20 becomes shallower from the groove center portion 20b toward the groove end portion 20a, and the groove bottom corner 20e of the radial cross section of the oil groove 20 has a circular arc. The radius Rw of the shape is made smaller (Rw1>Rw2>Rw3) from the groove center part 20b of the oil groove 20 toward the groove end part 20a.

15 and 16 are schematic diagrams illustrating an example in which the radial width D3 of the oil groove 20 is made smaller (narrower) from the groove center portion 20b toward the groove end portion 20a. The oil groove 20 shown in FIG. 16 has a substantially crescent shape with a pointed groove end 20a. In addition, in the oil groove 20 shown in FIGS. 15 and 16, the depth D4 of the oil groove 20 becomes shallower from the groove center portion 20b toward the groove end portion 20a, and the groove bottom corner 20e of the radial cross section of the oil groove 20 has a circular arc. The radius Rw of the shape is made smaller (Rw1>Rw2>Rw3) from the groove center part 20b of the oil groove 20 toward the groove end part 20a. With such a structure, the capillary force of the portion of the groove end 20a connected to the pocket surface 15a can be increased, and the lubricating oil accumulated at the groove bottom can be efficiently sucked up and supplied to the tapered roller 13. It becomes possible.

In addition, the circumferential length of the oil groove 20, the degree of change in the radial width D3 of the oil groove 20, the degree of change in the depth D4 of the oil groove 20, and the circular arc shape of the groove bottom corner 20e in the radial cross section of the oil groove 20. The degree of change in the radius Rw and the continuity or discontinuity of the change can be freely set. Also, only some of the above items may be adopted. Further, in the case of the oil groove 20 having the shape example shown in FIG. 11, the radial width D3 of the oil groove 20 is gradually reduced in the vicinity of the groove end 20a from the groove center portion 20b toward the groove end 20a. . Specifically, when the groove end 20a is viewed from the axial direction, the angle θ20a formed by the corner 20d of the portion constituting the groove end 20a is an acute angle in the range of 30 to 60 degrees (45 degrees in the case of FIG. 11). is set to . Further, in the case of the oil groove 20 having the shape example shown in FIG. 15, the ratio of the dimensions of the groove end portion 20a to the groove center portion 20b is such that the radial width D3 is approximately 50% and the depth D4 is approximately 25%. . In the case of the crescent-shaped oil groove 20 shown in FIG. 16, the ratio of the depth D4 near the groove end 20a to the groove center 20b is approximately 25%, and the angle θ20a formed by the groove end 20a is 30~30%. The acute angle is set within a range of 60 degrees (30 degrees in the case of FIG. 16).

In the tapered roller bearing 10 configured in this way, when lubricating oil is supplied to the bearing and the inside of the bearing is filled with lubricating oil, the lubricating oil flows from the small diameter side of the inner ring 12 to the large diameter side due to the pump action of the bearing rotation. A flowing phenomenon occurs. Therefore, in this embodiment, as shown in FIG. 5, the cage 14 moves in the axial direction toward the larger diameter side of the tapered rollers 13 under the force of the flow of lubricating oil due to the pump action, and the cage 14 The large diameter annular portion 15 moves away from the tapered rollers 13 (Dt=D2, D1=0). As a result, the large-diameter side annular portion 15 does not constantly contact the tapered rollers 13, so that an increase in frictional resistance during rotation of the bearing is suppressed. Furthermore, the lubricating oil supplied to the bearing is stored inside the oil groove 20 due to capillary force.

On the other hand, if no lubricating oil is supplied to the bearing and the lubricating oil inside the bearing is in a small amount, no lubricating oil flow occurs due to the pump action, and as shown in FIG. The tapered roller 13 moves axially toward the small diameter side, and the oil groove 20 formed in the pocket surface 15a of the large diameter annular portion 15 of the cage 14 comes into contact with the large diameter end surface 13b of the tapered roller 13 (Dt =D1, D2=0). As a result, the lubricating oil stored in the oil groove 20 is supplied to the large-diameter side end surface 13b of the tapered roller 13. In other words, the oil grooves 20 come into contact with the large-diameter end surfaces 13b of the tapered rollers 13, and the lubricating oil is supplied to the tapered rollers 13 only when there is a small amount of lubricating oil in the bearing. Note that since the tapered roller bearing 10 of the present invention moves the cage 14 using a component of the weight of the cage 14, it cannot be used in a structure that supports a horizontal shaft (horizontal shaft). is suitable.

As explained above, according to the tapered roller bearing 10 of this embodiment, the pocket surface 15a of the large-diameter side annular portion 15 of the cage 14 is provided with the fine oil grooves 20 that retain lubricating oil by capillary force. Therefore, the oil groove 20 alone can hold lubricating oil without covering the oil groove 20 with the tapered rollers 13. Furthermore, when the cage 14 moves in the axial direction toward the small diameter side of the tapered rollers 13, the oil grooves 20 come into contact with the large diameter side end surface 13b of the tapered rollers 13, so the lubricating oil is in an intermittent supply environment. Seizure of the bearing 10 can be prevented even under a lubricating environment where only a small amount of lubricating oil is present. Further, when the cage 14 moves in the axial direction toward the larger diameter side of the tapered rollers 13, the oil groove 20 separates from the larger diameter side end surface 13b of the tapered rollers 13, and the larger diameter side annular portion 15 moves toward the larger diameter side of the tapered rollers 13. Since it is not in constant contact with the bearing, it is possible to suppress an increase in frictional resistance during rotation of the bearing, and furthermore, it is possible to suppress wear of the large-diameter side annular portion 15. Furthermore, there is no need for sophisticated management of component dimensional accuracy, and an increase in manufacturing costs can be suppressed.

To explain in more detail, the large-diameter side annular portion 15 in which the oil groove 20 is formed has no contact force (pressing force) set in advance, but the tapered roller 13, almost no frictional resistance is generated, and wear and deterioration of the large-diameter side annular portion 15 can be minimized.

Further, according to the tapered roller bearing 10 of this embodiment, the cage 14 is made of synthetic resin, and the surface roughness of the pocket surface 15a of the large-diameter side annular portion 15 of the cage 14 and the oil groove 20 are axial. Since injection molding is performed simultaneously with the retainer 14 by drawing, an increase in manufacturing costs can be suppressed.

Further, according to the tapered roller bearing 10 of the present embodiment, the oil grooves 20 are formed along the circumferential direction, and the direction of action of centrifugal force during rotation of the bearing is orthogonal to the direction in which the oil grooves 20 are formed. It is possible to suppress the lubricating oil held in the container from scattering due to centrifugal force.

Further, according to the tapered roller bearing 10 of this embodiment, the amount of lubricating oil can be significantly reduced, so that the stirring resistance of the lubricating oil can be reduced. For example, if a structure is adopted in which even a small amount of lubricant can be supplied by splashing with gears (see Figure 22), the lubricant pump and oil supply path can be eliminated, which makes the entire lubrication system lighter and more compact. , it is possible to achieve cost reduction.

Further, according to the tapered roller bearing 10 of the present embodiment, even in a lubrication environment where lubricating oil is intermittently supplied into the bearing or where there is a small amount of lubricating oil inside the bearing, seizure can be prevented and the bearing can be maintained. Performance and lubrication effects can be maintained over a long period of time. Therefore, the tapered roller bearing 10 of this embodiment can be suitably used, for example, in a mechanism in which a lubricating oil pump is temporarily stopped when the engine is stopped, such as in the transmission of some hybrid vehicles. This can be used in situations where it is difficult to supply a sufficient amount of lubricant due to the lubricant pump not operating when the vehicle is being towed.

Here, a lubrication environment in which a small amount of lubricating oil is used in this specification will be explained. For example, in the case of a transmission such as an automobile, there are generally two methods for supplying lubricating oil: pumping the lubricating oil by a lubricating oil pump P shown in FIG. 21, and splashing the lubricating oil by a gear G shown in FIG. 22. known to.

As shown in FIG. 21, the structure for pumping lubricating oil by the lubricating oil pump P is such that the outer ring 11 of the tapered roller bearing 10 is fitted inside the housing H, the inner ring 12 is fitted outside the rotating shaft A, and the housing A structure in which an oil supply path R communicating with the bearing 10 is provided in H, and a lubricating oil pump P is connected to this oil supply path R is generally known. In the case of this structure, lubricating oil pressure-fed from the lubricating oil pump P is supplied to the bearing 10 via the oil supply path R.

Furthermore, as shown in FIG. 22, the structure in which lubricating oil is splashed by the gear G is such that the outer ring 11 of the tapered roller bearing 10 is fitted inside the housing H, the inner ring 12 is fitted outside the rotating shaft A, and the A structure in which a gear G is provided on the shaft A adjacent to the inner ring 12 is generally known. In the case of this structure, the lubricating oil adhering to the gear G is scattered by the centrifugal force accompanying the rotation of the shaft, and the scattered lubricating oil adheres to the bearing 10 and is supplied with oil.

In the above two types of structures, in order to prevent seizure of the bearing, lubricating oil is supplied in an amount of about 50 cc/min to 1000 cc/min. When the amount of lubricating oil is less than 10 cc/min, heat generation and seizure are likely to occur due to insufficient oil film due to lack of lubricating oil, and when the amount is 0 cc/min (no lubricating oil), seizure occurs. The present invention deals with a lean lubrication state rather than an unlubricated state, and has a large effect in a lubrication environment where a small amount of lubricating oil is present, specifically in a lean lubrication state of about 0.01cc/min to 10cc/min. demonstrate.

Next, an environment in which lubricating oil is intermittently supplied in this specification will be described. For example, in a hybrid car, there is a mode in which the electric motor is used to drive the car while the engine is stopped. In this mode, if the vehicle is configured with only a lubricating oil pump directly connected to the engine, the vehicle will run without lubricating oil being supplied to the bearings. For this reason, a state of no-lubrication occurs for up to several minutes, but the bearing must not seize during this time. There is a need to extend this electric driving time as batteries evolve. Currently, some car models are controlled to rotate the engine and operate the lubricating oil pump at regular intervals to prevent seizure. To solve this problem, it is necessary to add an electric lubricating oil pump to the system or to use a bearing like the present invention that does not require lubrication and is resistant to seizure. In the present invention, since the time until seizure is related to the amount of lubricating oil stored in the oil groove, increasing the amount of lubricating oil can significantly extend the no-lubrication application time from several tens of minutes to several hours. It is possible. The amount of lubricating oil can be increased by, for example, increasing the number of oil grooves or increasing the depth of the oil grooves.

In addition, passenger cars may be towed as auxiliary vehicles when a vehicle breaks down or when a large vehicle such as a camper is traveling. In such cases, it is possible to prevent the vehicle from idling by placing the drive wheels of the vehicle on a trolley or the like, but in reality, there are cases where the vehicle is towed while the drive wheels are idling. In this case, there is no drive transmission and the bearing idles under no load, so the load on the bearing is light. However, in the case of tapered roller bearings, they are generally used with a preload, so the load corresponding to the preload always acts on them. In this idling state, the engine and the electric lubricating oil pump do not operate, and the lubricating oil pump is stopped, so the bearing is likely to seize. To counter this problem, some vehicle models have devised drive systems that allow splash refueling to occur. In the present invention, even if the lubricating oil pump stops, the bearing can be lubricated until the lubricating oil stored in the oil groove runs out, so even when the bearing is being towed with insufficient splashing or no splashing, the seizure resistance is maintained. can be significantly improved.

Furthermore, when the engine is started in an extremely cold environment, the lubricating oil freezes, and there is a temporary phenomenon in which neither the lubricating oil pump nor the splashing lubrication occurs. In this case, until the frozen lubricating oil warms up and melts, lubrication must be provided by the small amount of oil adhering to the bearing itself. Further, in the present invention, since the frozen lubricating oil is stored in the oil groove, the lubricating oil is gradually melted as the bearing heats up, so that the seizure resistance can be dramatically improved.

Next, as a first modification of this embodiment, as shown in FIG. 17, two adjacent oil grooves 20 may be connected to each other by a connecting groove 22 extending in the radial direction. According to this modification, the amount of lubricating oil stored in the oil groove 20 can be increased, so that the seizure resistance of the bearing 10 in a lubrication environment with a small amount of lubricating oil can be further improved. Note that the number of connection grooves 22 is not limited to one, and may be plural.

In addition, as a second modification of the present embodiment, as shown in FIG. 18, three oil grooves 20 are formed in the pocket surface 15a of the retainer 14, and three adjacent oil grooves 20 are connected to each other extending in the radial direction. They may also be connected to each other by grooves 22. In addition, in this modification, a pair of end connecting sides 21, which are both end sides in the circumferential direction of the three oil grooves 20, are aligned with an arc-shaped line 21C that follows the annular contact surface 13e of the tapered roller 13. Each is provided. According to this modification, the amount of lubricating oil stored in the oil groove 20 can be increased, so that the seizure resistance of the bearing 10 in a lubrication environment with a small amount of lubricating oil can be further improved. Note that the number of connection grooves 22 is not limited to one, and may be plural.

In addition, as a third modification of the present embodiment, as shown in FIGS. 19 and 20, the pocket surface 15a of the retainer 14 is provided along a pair of straight lines 21L passing through the groove ends 20a of the two oil grooves 20. The bulging portions 15b may be formed respectively. Therefore, when the cage 14 moves to the small diameter side of the tapered rollers 13, the groove end 20a of the oil groove 20 contacts the large diameter side end surface 13b of the tapered roller 13, and the portion of the oil groove 20 other than the groove end 20a It does not come into contact with the large diameter side end surface 13b of the tapered roller 13. As a result, lubricating oil can be supplied from the groove end 20a of the oil groove 20 to the large-diameter end surface 13b of the tapered roller 13, and the pocket surface 15a of the cage 14 comes into contact with the large-diameter end surface 13b of the tapered roller 13. It is possible to reduce the frictional resistance when

It should be noted that the present invention is not limited to what has been exemplified in the above embodiments, and can be modified as appropriate without departing from the gist of the present invention.

10 Tapered roller bearing 11 Outer ring 11a Outer ring raceway surface 12 Inner ring 12a Inner ring raceway surface 13 Tapered rollers 13a Rolling surface 13b Large diameter end surface 13c Small diameter end surface 13d Recess 13e Annular contact surface 14 Cage 15 Large diameter annular portion 15a Axial inner end surface (pocket surface)
16 Small diameter annular portion 16a Axial inner end surface 17 Pillar portion 18 Pocket 20 Oil groove 20a Groove end 20b Groove center portion 20c Wall surface 20d Corner portion 20e Groove bottom corner in radial cross section 20f Groove bottom corner in circumferential cross section 21 End portion Connecting side 21L Pair of straight lines L Lubricating oil S1 First gap S2 Second gap D1 First gap dimension in roller axial direction D2 Second gap dimension in roller axial direction D3 Radial width of oil groove D4 Depth of oil groove Dt Gap Total dimension of the entire roller in the axial direction LR Length dimension of the tapered roller LP Length dimension of the pocket in the axial direction of the roller Ra Radius of curvature of the large-diameter end face of the tapered roller SRy Radius of curvature of the pocket surface

Claims (5)

an outer ring having an outer ring raceway surface on its inner peripheral surface; an inner ring having an inner ring raceway surface on its outer peripheral surface; a plurality of tapered rollers rotatably provided between the outer ring raceway surface and the inner ring raceway surface; a cage that holds the tapered rollers at approximately equal intervals in the circumferential direction;
The retainer includes a large-diameter annular portion, a small-diameter annular portion disposed coaxially with the large-diameter annular portion, and an axis that connects the large-diameter annular portion and the small-diameter annular portion. a plurality of pillars connected in the direction and provided at approximately equal intervals in the circumferential direction; and a pocket formed between the pillars adjacent to each other in the circumferential direction and holding the tapered roller in a rollable manner. A roller bearing,
The retainer has a first gap between the axial inner end surface of the small diameter annular portion and the small diameter end surface of the tapered roller, and a first gap between the axial inner end surface of the large diameter annular portion and the tapered roller. having a second gap between the roller and the large-diameter end face of the roller, and being movable within a predetermined range along the axial direction;
A plurality of oil grooves for retaining lubricating oil by capillary force are provided on the axially inner end surface of the large-diameter side annular portion,
When the cage moves axially toward the small diameter side of the tapered rollers, the plurality of oil grooves come into contact with the large diameter end surface of the tapered rollers, and the cage moves axially toward the large diameter side of the tapered rollers. when the plurality of oil grooves move away from the large diameter side end surface of the tapered roller ,
The plurality of oil grooves are formed in parallel along the circumferential direction of the retainer,
Each of the plurality of oil grooves has a groove end that can come into contact with the large diameter side end surface of the tapered roller,
The large-diameter end surface of the tapered roller has a circular recess formed at the center of the large-diameter end surface, and is provided around the recess and comes into contact with an axially inner end surface of the large-diameter annular portion. a possible toroidal contact surface;
The groove ends of each of the plurality of oil grooves are provided so as to fit in a region where the annular contact surface and the axial inner end surface of the large-diameter annular portion overlap in the longitudinal direction of the tapered roller.
A tapered roller bearing characterized by: The axially inner end surface of the large-diameter side annular portion is formed in a concave spherical shape, and the large-diameter side end surface of the tapered roller is formed in a convex spherical shape,
The radius of curvature SRy of the concave spherical surface of the axially inner end surface of the large-diameter side annular portion is set within ±10% of the radius of curvature Ra of the convex spherical surface of the large-diameter side end surface of the tapered roller. The tapered roller bearing according to claim 1. Each of the plurality of oil grooves is formed in an annular fan shape,
A pair of end connecting sides, which are both end sides in the longitudinal direction of the plurality of oil grooves, are each provided so as to be aligned with a pair of straight lines,
2. The tapered roller bearing according to claim 1 , wherein the pair of straight lines are inclined lines such that a circumferential interval between them increases as the line goes radially inward of the large-diameter side annular portion. The tapered roller bearing according to claim 1 , wherein the plurality of adjacent oil grooves are connected to each other by at least one connection groove. The cone according to any one of claims 1 to 4 , characterized in that the cone is used under a lubrication environment in which lubricating oil is intermittently supplied into the bearing, or in which a small amount of lubricating oil is present inside the bearing. roller bearings.

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