JP2007120575A - Tapered roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent increase in the load capacity and damage of a raceway surface due to excess surface pressure by increasing the number of rollers, substantialize low torque without deteriorating the rigidity of a bearing, and suppress the occurrence of dragging torque. <P>SOLUTION: The tapered roller bearing comprises an inner ring 2, an outer ring 3, a plurality of tapered rollers 4 which are disposed between the inner ring 2 and the outer ring 3 and is capable of freely rolling the between those rings, and a retainer 5 circumferentially holding the tapered rollers 4 thereon at specified intervals. A pocket 9 between adjacent column parts 8 is formed in such a trapezoidal shape that its portion storing the small diameter side of the tapered rollers 4 is formed narrow and its portion storing the large diameter side of the tapered rollers 4 is formed wide. A cutout part 10a is provided to the column part 8 on the narrow side of the pocket 9. The roller factor is set to exceed 0.94. Inter-contact width of the roller in a pocket column surface is secured at 10% or more of pocket length in the axial direction from a central position of the pocket 9. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tapered roller bearing and can be applied to a bearing that supports a power transmission shaft such as a differential of a self-propelled vehicle or a transmission.

  Tapered roller bearings consist of an inner ring with small and large collars on both sides of the raceway surface of the outer diameter surface, an outer ring with a raceway surface on the inner diameter surface, and a plurality of rows arranged between the raceway surfaces of the inner ring and the outer ring. And a retainer that holds and stores these tapered rollers in a pocket. The retainer is connected to a small annular portion that is continuous on the small diameter end surface side of the tapered roller, and is connected on the large diameter end surface side of the tapered roller. A base composed of a large annular portion and a plurality of column portions connecting these annular portions, wherein the pocket has a narrow side on the small diameter side of the tapered roller and a wide side on the large diameter side. What was formed in the shape is used.

  Tapered roller bearings that support power transmission shafts such as differentials and transmissions of self-propelled vehicles are used with the lower part immersed in an oil bath, and the oil in the oil bath flows into the bearing as lubricating oil as it rotates. . In tapered roller bearings used for such applications, the lubricating oil flows into the bearing from the small diameter side of the tapered roller, and the lubricating oil flowing from the outer diameter side of the cage flows along the raceway surface of the outer ring. The lubricating oil that passes to the larger diameter side and flows from the inner diameter side to the cage passes along the raceway surface of the inner ring to the larger diameter side of the tapered roller.

  In such a tapered roller bearing used for a portion where the lubricating oil flows from the outside, a notch is provided in the pocket of the cage, and the lubricating oil that flows into the outer diameter side and the inner diameter side of the cage is separated. There is one that passes through this notch to improve the flow of lubricating oil inside the bearing (see Patent Documents 1 and 2). 18A, a notch 10d is provided in the center portion of the column portion 8 between the pockets 9 of the cage 5, and foreign matter mixed in the lubricating oil is generated inside the bearing as shown in FIG. So that it does not stay. Moreover, in what was described in patent document 2, as shown to FIG. 18 (B), the notch 10e is provided in the small annular part 6 and the large annular part 7 of the axial direction both ends of the pocket 9 of the holder | retainer 5, and hold | maintained. The lubricating oil flowing in from the outer diameter side of the vessel is made easier to flow to the inner ring side. In addition, each dimension of the pocket 9 entered in each figure is the value used for the comparative example in the torque measurement test mentioned later.

  By the way, in recent years, low-viscosity oil tends to be used for automobile transmissions in order to achieve mission AT, CVT, fuel efficiency, and the like. In an environment where low-viscosity oil is used, it is caused by poor lubrication when adverse conditions such as (1) high oil temperature, (2) low oil volume, and (3) preload loss occur. Very short-life surface-origin separation may occur on the inner ring raceway surface with high surface pressure.

  As a countermeasure for short life due to this surface-origin separation, reduction of the maximum surface pressure is a direct and effective solution. In order to reduce the maximum surface pressure, the bearing dimensions are changed, or if the bearing dimensions are not changed, the number of rollers of the bearing is increased. In order to increase the number of rollers without reducing the roller diameter, the pocket interval of the cage must be narrowed. For this purpose, it is necessary to enlarge the pitch circle of the cage and bring it closer to the outer ring side as much as possible.

As an example in which the cage is brought into contact with the inner surface of the outer ring, there is a tapered roller bearing shown in FIG. 14 (see Patent Document 6). The tapered roller bearing 61 guides the cage 62 by sliding the outer peripheral surface of the small-diameter side annular portion 62 a and the outer peripheral surface of the large-diameter side annular portion 62 b with the inner surface of the outer ring 63. In order to suppress drag torque on the outer diameter surface of the portion 62c, a recess 64 is formed to maintain a non-contact state between the outer diameter surface of the column portion 62c and the raceway surface 63a of the outer ring 63. The retainer 62 includes a plurality of small-diameter-side annular portions 62a, large-diameter-side annular portions 62b, small-diameter-side annular portions 62a, and large-diameter-side annular portions 62b that are axially connected to each other so that a recess 64 is formed on the outer diameter surface. Column part 62c. A plurality of pockets are provided between the column portions 62c for accommodating the tapered rollers 65 in a rollable manner. The small-diameter-side annular portion 62a is provided with a collar portion 62d that extends integrally on the inner-diameter side. The tapered roller bearing of FIG. 14 is intended to improve the strength of the cage 62, and is an example in which the cage 62 is brought into contact with the inner diameter surface of the outer ring 63 in order to increase the circumferential width of the column portion 62c of the cage 62. It is.
JP 09-32858 A (FIG. 3) JP-A-11-2011149 (FIG. 2) JP 09-096352 A Japanese Patent Laid-Open No. 11-0210765 JP 2003-343552 A JP 2003-28165 A

  As described in Patent Document 1 and Patent Document 2, in the tapered roller bearing in which the lubricating oil is divided into the outer diameter side and the inner diameter side of the cage and flows into the bearing, it flows from the inner diameter side of the cage to the inner ring side. It has been found that torque loss increases as the proportion of lubricating oil increases. The reason is considered as follows.

  That is, the lubricating oil flowing from the outer diameter side of the cage to the outer ring side smoothly passes to the large diameter side of the tapered roller along the raceway surface because there is no obstacle on the inner diameter surface of the outer ring. The lubricating oil flowing out from the inner diameter side of the cage to the inner ring side has a large brim on the outer diameter surface of the inner ring, so when it passes along the raceway surface to the larger diameter side of the tapered roller It is blocked by a large brim and tends to stay inside the bearing. For this reason, when the ratio of the lubricating oil flowing from the inner diameter side to the inner ring side of the cage increases, the amount of the lubricating oil staying inside the bearing increases, and this staying lubricating oil becomes a flow resistance against the bearing rotation and generates torque. Loss is considered to increase.

  Therefore, it is necessary to reduce torque loss due to flow resistance of the lubricating oil in the tapered roller bearing in which the lubricating oil flows into the bearing. The above is a method for reducing the flow resistance of oil to reduce torque, but in order to significantly reduce torque, it is necessary to change the bearing specifications so that the rolling viscous resistance decreases. . However, in the conventional torque reduction method (see Patent Documents 3 to 5), torque reduction without reducing the rated load is possible, but the bearing rigidity is somewhat reduced.

  In the tapered roller bearing 61 described in Patent Document 6, it is possible to increase the roller filling rate and reduce the raceway maximum surface pressure compared to the type in which the cage and the outer ring do not contact each other. However, since the cage and the center portion of the raceway surface are not in contact with each other, there is a demerit that the thickness of the portion is reduced. That is, since the recesses 64 are provided in the column portion 62c of the cage 62, the plate thickness is inevitably reduced, the rigidity of the cage 62 is reduced, and the cage 62 is deformed by the stress when the bearing 61 is assembled, There is also a possibility that the cage 62 is deformed while the bearing 61 is rotating. If the rigidity of the retainer 62 is increased, the diameter of the retainer 62 is increased, which may cause an increase in torque due to sliding contact at the outer ring contact portion, so-called drag torque.

On the other hand, a conventional typical tapered roller bearing with a cage other than the tapered roller bearing described in Patent Document 6 avoids contact between the outer ring 71 and the cage 72 as shown in FIG. In order to secure the width and obtain an appropriate column strength and smooth rotation of the retainer 72, the roller coefficient (roller filling rate) γ defined by the following equation is usually required to be 0.94 or less. (See Patent Document 4).
Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: number of rollers, DA: roller average diameter, PCD: roller pitch circle diameter. In FIG. 15, reference numeral 73 is a tapered roller, 74 is a column surface, 75 is an inner ring, and θ is a window angle.

  If an attempt is made to simply increase the roller filling rate while keeping the pocket size of the cage 72 as it is, the column 72a of the cage 72 becomes thin, and sufficient column strength cannot be ensured. On the other hand, if the diameter of the cage is changed (increase the diameter) in such a direction that the clearance between the cage and the outer ring becomes smaller in order to ensure the column strength, as introduced in Patent Document 6, contact with the outer ring of the cage. There is a possibility that the wear at the part is accelerated and the drag torque is increased.

  The object of the present invention is to increase the number of rollers to prevent an early breakage due to an increase in load capacity and excessive surface pressure of the raceway surface, and to realize a reduction in torque without reducing bearing rigidity. An object of the present invention is to provide a tapered roller bearing capable of suppressing the generation of drag torque.

  The present invention relates to a tapered roller bearing comprising an inner ring, an outer ring, a plurality of tapered rollers arranged to roll between the inner ring and the outer ring, and a cage that holds the tapered rollers at a predetermined circumferential interval. The retainer is composed of a small annular portion that is continuous on the small diameter end surface side of the tapered roller, a large annular portion that is continuous on the large diameter end surface side of the tapered roller, and a plurality of column portions that connect these annular portions. A trapezoidal pocket is formed between the two parts, with the narrow side of the tapered roller storing the narrow side and the wide side storing the large diameter side, and is cut into the column on the narrow side of the pocket. A notch is provided, the roller coefficient exceeds 0.94, and the contact width of the roller on the pocket column surface is secured at least 10% of the pocket length with respect to the central position in the pocket axial direction on both the left and right sides. is there.

  The contact width of the roller on the pocket column surface is 10% or more of the pocket length with respect to the central position in the pocket axial direction on both the left and right sides, and the load acting on the cage from the rollers is concentrated locally or unevenly applied. As a result, abnormal wear or damage due to stress concentration does not occur. As a result, the roller coefficient γ can be set to γ> 0.94.

  The roller coefficient γ (roller filling ratio) is a parameter represented by (number of rollers × roller average diameter) / (π × PCD). When the average roller diameter is constant, the larger the value of γ, the greater the number of rollers. It means that there are many. In a conventional typical tapered roller bearing with a cage, the roller coefficient γ is usually designed to be 0.94 or less, so that the roller coefficient γ exceeds 0.94, This means that the roller filling rate and thus the bearing rigidity is high.

  FIG. 19 shows the rigidity ratio (-●-) and torque ratio (-o-) when the roller pitch diameter (PCD) is changed in the tapered roller bearing. As shown in FIG. 19, when the PCD is reduced, the bearing torque is significantly reduced, but the bearing rigidity is not reduced so much as a result of calculating and confirming the elastic deformation amount of the roller. Therefore, if the PCD is reduced while the number of rollers is not reduced or increased, the torque can be reduced without reducing the rigidity.

  In the present invention, the roller PCD can be reduced while increasing the number of rollers by making the roller coefficient γ exceed 0.94. Thereby, low torque can be realized without reducing the bearing rigidity. In addition, increasing the number of rollers not only increases the load capacity, but also reduces the maximum surface pressure of the raceway surface.

  In addition, by providing a notch in the narrow column of the trapezoidal pocket of the cage, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side can be quickly released to the outer ring side through this notch. Can do.

  According to a second aspect of the present invention, in the tapered roller bearing according to the first aspect, a notch is also provided in the small annular portion on the narrow side of the pocket. By adopting such a configuration, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side can be released from the notch to the outer ring side.

  According to a third aspect of the present invention, in the tapered roller bearing of the first or second aspect, a notch is provided in at least a column portion on the wide side of the pocket.

  According to a fourth aspect of the present invention, in the tapered roller bearing of the third aspect, the total area of the notches provided on the narrow side of the pocket is made wider than the total area of the notches provided on the wide side of the pocket. It is what.

  According to a fifth aspect of the present invention, in the tapered roller bearing according to any one of the first to fourth aspects, a radially inwardly facing outer diameter surface of the small collar of the inner ring is provided on the outer side in the axial direction of the small annular portion of the cage. A collar is provided, and the upper limit of the clearance between the inner diameter surface of the collar and the outer diameter surface of the small collar of the inner ring is set to 2.0% of the outer diameter dimension of the small collar.

  According to a sixth aspect of the present invention, in the tapered roller bearing according to any one of the first to fifth aspects, an infinite number of minute concave concaves are randomly provided on at least the surface of the tapered roller, and the surface roughness of the surface provided with the concaves is provided. The parameter Ryni is 0.4 μm ≦ Ryni ≦ 1.0 μm, and the Sk value is −1.6 or less.

  The parameter Ryni is the average value of the maximum height for each reference length, that is, the reference length is extracted from the roughness curve in the direction of the average line, and the interval between the peak line and the valley bottom line of this extracted part is set to the vertical line of the roughness curve. It is a value measured in the direction of magnification (ISO 4287: 1997). The Sk value is a value representing the degree of distortion of the roughness curve, that is, the asymmetry of the roughness unevenness distribution (ISO 4287: 1997), and the Sk value is close to 0 in a symmetric distribution such as a Gaussian distribution. When the concave and convex portions are deleted, a negative value is obtained. Conversely, when the concave portions are deleted, a positive value is obtained. The Sk value can be controlled by selecting the rotational speed of the barrel polishing machine, the processing time, the workpiece input amount, the type and size of the polishing tip, etc., and by setting the Sk value to −1.6 or less, Lubricating oil can be held evenly in innumerable minute concave recesses.

  A seventh aspect of the present invention is the tapered roller bearing according to any one of the first to sixth aspects, wherein a clearance exists between the outer diameter of the cage and the outer ring raceway surface when the cage is located at the center of the shaft. It is what. By adopting a cage size in which a clearance exists, contact between the outer ring and the cage hardly occurs during the bearing operation.

  Each of the tapered roller bearings described above is suitable for supporting a power transmission shaft of a self-propelled vehicle.

  According to the present invention, the PCD can be reduced while increasing the number of rollers by making the roller coefficient γ exceed 0.94. Thereby, low torque can be realized without reducing the bearing rigidity. In addition, increasing the number of rollers not only increases the load capacity, but also reduces the maximum surface pressure of the raceway surface, thus preventing surface-origin separation with an extremely short life under severe lubrication conditions. be able to.

  In addition, by providing a notch in the narrow pillar portion of the trapezoidal pocket of the cage, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side can be quickly released to the outer ring side through this notch. As a result, the amount of lubricating oil reaching the large collar along the raceway surface of the inner ring is reduced, the amount of lubricating oil remaining in the bearing is reduced, and torque loss due to the flow resistance of the lubricating oil is reduced.

  By providing a notch also in the small annular part on the narrow side of the pocket, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side is released from the notch of the small annular part to the outer ring side, and the inner ring raceway It is possible to further reduce the torque loss due to the flow resistance of the lubricating oil by reducing the amount of lubricating oil reaching the large brim along the surface.

  By providing a notch in at least the column portion on the wide side of the pocket, the tapered roller can be slidably contacted with the column portion in a balanced manner.

  Even by making the total area of the notches provided on the narrow side of the pocket larger than the total area of the notches provided on the wide side of the trapezoidal pocket, it can reach a large brim along the raceway surface of the inner ring. It is possible to further reduce torque loss due to the flow resistance of the lubricating oil by reducing the amount of the lubricating oil.

  A radially inward flange is provided on the outer side of the small annular portion of the cage in the radial direction so as to face the outer diameter surface of the small collar of the inner ring. By setting the clearance between the outer diameter surface of the collar to 2.0% or less of the outer diameter of the small collar of the inner ring, the amount of lubricating oil flowing from the inner diameter side of the cage to the inner ring side is reduced, and the lubricating oil Torque loss due to the flow resistance can be further reduced.

  At least the surface of the tapered roller is provided with an infinite number of minute concave concaves, the surface roughness parameter Ryni of the surface provided with the concaves is 0.4 μm ≦ Ryni ≦ 1.0 μm, and the Sk value is Even if the amount of lubricating oil staying in the bearing is reduced by holding the lubricating oil evenly on the surface of the tapered roller by setting it to -1.6 or less, the contact portion between the tapered roller and the inner and outer rings is sufficiently lubricated. can do.

  When the cage is located at the center of the shaft, there is a clearance between the outer diameter of the cage and the raceway surface of the outer ring, so there is almost no contact between the outer ring and the cage during bearing operation. Increase and wear can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings.

  A tapered roller bearing 1 according to the embodiment shown in FIG. 1 includes an inner ring 2, an outer ring 3, a tapered roller 4, and a cage 5. The inner ring 2 has a conical track surface 2a on the outer periphery, and the outer ring 3 has a conical track surface 3a on the inner periphery. A plurality of tapered rollers 4 are interposed between the raceway surface 2a of the inner ring 2 and the raceway surface 3a of the outer ring 3 so as to be freely rollable. The tapered roller 4 is accommodated in a pocket 9 formed in the cage 5. Each tapered roller 4 is restricted from moving in the axial direction by a small brim 2 b and a large brim 2 c provided on both sides of the raceway surface 2 a of the inner ring 2.

  The cage 5 connects the small annular part 6 connected on the small diameter end face side of the tapered roller 4, the large annular part 7 connected on the large diameter end face side of the tapered roller 4, and the small annular part 6 and the large annular part 7. A plurality of column portions 8 are included. Then, as shown in FIG. 2, a pocket 9 is formed between the adjacent column portions 8. The pocket 9 of the cage 5 has a trapezoidal shape, and the portion for storing the small diameter side of the tapered roller 4 is the narrow side, and the portion for storing the large diameter side is the wide side. On the narrow side and wide side of the pocket 9, two notches 10 a and 10 b that are cut from the outer diameter side to the inner diameter side are provided in each of the column portions 8 on both sides. Each notch 10a, 10b has a depth of 1.0 mm and a width of 4.6 mm. The notches 10a and 10b illustrated in the drawings are in the form of grooves cut in the radial direction of the cage 5, but the inner diameter side and the outer diameter side of the cage 5 are connected to make the lubricating oil smooth. As long as the passage can be allowed, the shape and dimensions are arbitrary. Further, the window angle θ (see FIG. 15) of the column surface 5d is, for example, 25 ° to 50 °.

  3 and 4 show a modified example of the cage 5. In the modification shown in FIG. 3, a notch 10 c is also provided in the small annular portion 6 on the narrow side of the pocket 9. The total area of the three notches 10a and 10c on the narrow side is wider than the total area of the two notches 10b on the wide side. The notch 10c has a depth of 1.0 mm and a width of 5.7 mm.

  In the modification shown in FIG. 4, the depth of each notch 10a of the narrow column portion 8 is 1.5 mm, which is deeper than each notch 10b of the wide column portion 8, and each notch on the narrow side. The total area of 10a is wider than the total area of the notches 10b on the wide side.

  As shown in FIG. 5, a radially inward flange 11 is provided on the outer side in the axial direction of the small annular portion 6 of the cage 5 so as to face the outer diameter surface of the small collar 2b of the inner ring 2. The clearance δ between the inner diameter surface of 11 and the outer diameter surface of the small collar 2b of the inner ring 2 is set narrowly to 2.0% or less of the outer diameter dimension of the small collar 2b.

  Although not shown in the figure, the entire surface of the tapered roller 4 is provided with an infinite number of minute concave concaves. The surface provided with the indentation has a surface roughness parameter Ryni of 0.4 μm ≦ Ryni ≦ 1.0 μm and a Sk value of −1.6 or less.

  FIG. 12 exemplifies the configuration of a vehicle differential that can use the tapered roller bearing described above. This differential is connected to a propeller shaft (not shown), and a drive pinion 22 inserted into the differential case 21 meshes with a ring gear 24 attached to the differential gear case 23, and a pinion gear 25 attached to the inside of the differential gear case 23. However, the drive gear of the engine is transmitted from the propeller shaft to the left and right drive shafts by meshing with the side gear 26 coupled to the drive shaft (not shown) inserted into the differential gear case 23 from the left and right. In this differential, a drive pinion 22 that is a power transmission shaft and a differential gear case 23 are supported by a pair of tapered roller bearings 1a and 1b, respectively.

  The differential case 21 is sealed with seal members 27a, 27b, and 27c, and the lubricating oil is stored inside. Each tapered roller bearing 1a, 1b rotates with its lower part immersed in this lubricating oil bath.

  When each tapered roller bearing 1a, 1b rotates at high speed and its lower part is immersed in an oil bath, the lubricating oil in the oil bath is drawn from the small diameter side of the tapered roller 4 to the outer diameter of the cage 5 as shown by arrows in FIG. The lubricating oil that flows into the bearing divided into the inner diameter side and the inner diameter side and flows into the outer ring 3 from the outer diameter side of the cage 5 passes along the raceway surface 3 a of the outer ring 3 to the larger diameter side of the tapered roller 4. Out of the bearing. On the other hand, the lubricating oil flowing from the inner diameter side of the cage 5 to the inner ring 2 side is far less than the lubricating oil flowing from the outer diameter side of the cage 5, and most of the lubricating oil flowing from this clearance δ is Then, it passes through the notch 10 a provided in the column portion 8 on the narrow side of the pocket 9 and moves to the outer diameter side of the cage 5. Therefore, the amount of the lubricating oil that reaches the large collar 2c along the raceway surface 2a of the inner ring 2 becomes very small, and the amount of the lubricating oil staying inside the bearing can be reduced.

Here, the cage 5 is made of an iron plate and can be used without worrying about material deterioration (oil resistance) due to immersion in oil. The cage 5 is made of, for example, PPS, PEEK, PA, PPA, P instead of iron plate.
You may integrally mold with super engineering plastics, such as AI. In the case of an iron plate cage, it is necessary to spread the bottom and caulking, but in the case of a resin cage, these are not necessary, so that it is easy to ensure the required dimensional accuracy. Here, “bottom opening” means that when the cage 5 incorporating the roller is assembled to the inner ring, the diameter of the column portion on the small diameter side of the cage 5 is greatly expanded so that the roller can get over the small brim of the inner ring. . “Caulking operation” refers to pushing the column portion of the small-diameter portion of the cage 5 greatly expanded as described above by pushing it with a mold from the outside.

  In addition, by using engineering plastics with excellent mechanical strength, oil resistance and heat resistance for the cage, the cage weight is lighter, self-lubricating, and the friction coefficient is smaller than the steel plate cage. Therefore, it is possible to suppress the occurrence of wear due to contact with the outer ring in combination with the effect of the lubricating oil interposed in the bearing. In addition, these resins are lighter and have a smaller coefficient of friction than steel plates, and are therefore suitable for reducing torque loss and cage wear at the start of the bearing.

  Engineering plastics include general purpose engineering plastics and super engineering plastics. Typical examples are listed below, but these are examples of engineering plastics, and engineering plastics are not limited to the following.

[General-purpose engineering plastics] Polycarbonate (PC), polyamide 6 (PA6), polyamide 66 (PA66), polyacetal (POM), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), GF reinforced polyethylene terephthalate (GF) -PET), ultra high molecular weight polyethylene (UHMW-PE)

[Super Engineering Plastics] Polysulfone (PSF), Polyethersulfone (PES), Polyphenylene sulfide (PPS), Polyarylate (PAR), Polyamideimide (PAI), Polyetherimide (PEI), Polyetheretherketone ( PEEK), liquid crystal polymer (LCP), thermoplastic polyimide (TPI), polybenzimidazole (PBI), polymethylbenten (TPX), poly1,4-cyclohexanedimethylene terephthalate (PCT), polyamide 46 (PA46), polyamide 6T (PA6T), polyamide 9T (PA9T), polyamide 11,12 (PA11,12), fluororesin, polyphthalamide (PPA)

  In addition, although super engineering plastics, such as PPS, PEEK, PA, PPA, and PAI, were mentioned as an example of cage materials other than the iron plate, if necessary, to these resin materials or other engineering plastics, You may use what mix | blended glass fiber or carbon fiber.

The tapered roller bearing 1 has a roller coefficient γ of γ> 0.94. The roller coefficient γ represents the filling rate of the roller and is defined by the following equation.
Roller coefficient γ = (Z · DA) / (π · PCD)
here,
Z: Number of rollers DA: Roller average diameter PCD: Roller pitch diameter.

  By the way, the outer diameter of the cage 5 is moved from the state of FIG. 6A to the axially smaller diameter side as shown by the arrow in FIG. 6B (FIG. 6B), and then FIG. When the outer ring 3 and the cage 5 are brought into contact with each other as shown in FIG. 7A, the bearing 5 is rotated and the cage 5 is centered as shown in FIG. The dimensions are set such that the outer ring 3 is not contacted with a predetermined clearance all around. In other words, such a dimension means that the clearance between the retainer 5 and the outer ring 3 is such that the retainer 5 is disposed at the axial center and the retainer 5 is closer to the small diameter side as shown in FIG. Although it exists, the outer ring 3 and the cage 5 are in contact with each other when the cage 5 is moved in the radial direction from the axial center. As a result, the outer ring 3 and the cage 5 are in contact with each other at the initial stage of operation (FIG. 7B), but are not in contact with each other during operation (FIG. 7C). Can be suppressed.

  8 to 11 show pockets viewed from the inner diameter side of the cage 5, and the contact of the rollers with the pocket column surface 5a (side surface of the column) is indicated by a two-dotted line. In any case, the contact width of the roller of the pocket column surface 5a is secured 10% or more of the pocket length from the axial center position of the pocket 9, that is, the pocket central position. This is because the load acting on the cage 5 from the rollers is concentrated locally or biased so that abnormal wear does not occur and damage due to stress concentration does not occur. 8 to 11, the notch 10a and the like are omitted.

  Specifically, in the case of FIG. 8, the roller contact width is secured over 10% or more of the pocket length from the pocket center position to both sides in the axial direction. Therefore, the roller contact width at the pocket center position is 20% or more of the pocket length. In the case of FIG. 9, the roller contact is closer to the left side in the figure, but a roller contact width of 10% or more of the pocket length is also secured from the center of the pocket to the right side. In the case of FIG. 10, the roller contact is closer to the right side in FIG. 9, but a roller contact width of 10% or more of the pocket length is secured on the left side from the pocket center position. FIG. 11 shows a case where the contact of the rollers is offset in the opposite direction between the upper pocket column surface 5a and the lower pocket column surface 5a in the drawing. In any case, at least the pocket length from the pocket center position is shown. A width per roller of 10% or more is secured.

  According to the present invention, the PCD can be reduced while increasing the number of rollers by making the roller coefficient γ exceed 0.94. Thereby, a reduction in torque can be realized without lowering the bearing rigidity. In addition, increasing the number of rollers not only increases the load capacity, but also reduces the maximum surface pressure of the raceway surface, thus preventing surface-origin separation with an extremely short life under severe lubrication conditions. be able to.

  Further, by providing a notch 10 in the narrow pillar portion 8 of the trapezoidal pocket 9 of the cage 5, the lubricating oil flowing from the inner diameter side of the cage 5 to the inner ring side is passed through the notch 10 to the outer ring. Since the amount of lubricating oil reaching the collar 2c along the raceway surface 2a of the inner ring 2 is reduced, the amount of lubricating oil staying inside the bearing is reduced, and the flow of lubricating oil is reduced. Torque loss due to resistance is reduced.

  By providing a notch 10 c also in the small annular portion 6 on the narrow side of the pocket 9, the lubricating oil flowing from the inner diameter side of the cage 5 to the inner ring side can be supplied from the notch 10 c of the small annular portion 6 to the outer ring 3. The amount of lubricating oil that escapes to the side and reaches the collar 2c along the raceway surface 2a of the inner ring 2 can be further reduced, and torque loss due to the flow resistance of the lubricating oil can be further reduced.

  By providing the notch 10b in at least the column portion 8 on the wide side of the pocket 9, the tapered roller 4 can be brought into sliding contact with the column portion in a balanced manner.

  The total area of the notches 10a provided on the narrow side of the pocket 9 can be made larger than the total area of the notches 10b provided on the wide side of the trapezoidal pocket 9 along the raceway surface of the inner ring 2. Thus, the amount of the lubricating oil reaching the largest collar 2c can be reduced, and the torque loss due to the flow resistance of the lubricating oil can be further reduced.

  A radially inward flange 11 facing the outer diameter surface of the small collar 2b of the inner ring 2 is provided on the outer side in the ring direction of the small annular section 6 of the cage 5, and the collar 11 of the opposed small annular section 6 is provided. By setting the clearance δ between the inner diameter surface of the inner ring 2 and the outer diameter surface of the small collar 2b of the inner ring 2 to 2.0% or less of the outer diameter dimension of the small collar 2c of the inner ring 2, the inner diameter side of the cage 5 The amount of lubricating oil flowing into the engine can be reduced, and torque loss due to the flow resistance of the lubricating oil can be further reduced.

  At least the surface of the tapered roller 4 is provided with an infinite number of minute concave recesses, and the surface roughness parameter Ryni of the surface provided with these recesses is 0.4 μm ≦ Ryni ≦ 1.0 μm, and the Sk value Even if the amount of the lubricating oil staying inside the bearing is reduced by keeping the lubricating oil evenly on the surface of the tapered roller 4 by reducing the value to −1.6 or less, the tapered roller 4 and the inner and outer rings 2, 3 The contact portion can be sufficiently lubricated.

  In the state where the cage is located at the center of the shaft, there is a clearance between the outer diameter of the cage and the raceway surface of the outer ring, so that contact between the outer ring and the cage hardly occurs during the bearing operation. For this reason, generation | occurrence | production of the drag torque by the contact of a holder | retainer can be suppressed, and abrasion of a holder | retainer pocket part can also be minimized.

  FIG. 13 shows a configuration example of an automobile transmission that can use the tapered roller bearing described above. This transmission is of a synchronous mesh type, and in the figure the left direction is the engine side and the right direction is the drive wheel side. A tapered roller bearing 43 is interposed between the main shaft 41 and the main drive gear 42. In this example, the outer ring raceway surface of the tapered roller bearing 43 is directly formed on the inner periphery of the main drive gear 42. The main drive gear 42 is rotatably supported with respect to the casing 45 by a tapered roller bearing 44. A clutch gear 46 is engaged and connected to the main drive gear 42, and a synchronization mechanism 47 is disposed in the vicinity of the clutch gear 46.

  The synchronizer 47 includes a sleeve 48 that moves in the axial direction (left and right in the figure) by the operation of a selector (not shown), a synchronizer key 49 that is mounted on the inner periphery of the sleeve 48 so as to be axially movable, A hub 50 engaged and connected to the outer periphery of the shaft 41, a synchronizer ring 51 slidably mounted on the outer periphery (cone portion) of the clutch gear 46, and a synchronizer key 49 are elastically attached to the inner periphery of the sleeve 48. A pressing pin 52 and a spring 53 are provided.

  In the state shown in the figure, the sleeve 48 and the synchronizer key 49 are held in the neutral position by the pressing pin 52. At this time, the main drive gear 42 idles with respect to the main shaft 41. On the other hand, when the sleeve 48 is moved to the left side in the axial direction, for example, by the operation of the selector, the synchronizer key 49 is moved to the left side in the axial direction following the sleeve 48, and the synchronizer ring 51 is moved to the clutch gear 46. Press against the inclined surface of the cone. As a result, the rotational speed of the clutch gear 46 decreases, and conversely, the rotational speed on the synchro mechanism 47 side is increased. When the rotational speeds of the two are synchronized, the sleeve 48 further moves to the left in the axial direction, meshes with the clutch gear 46, and the main shaft 41 and the main drive gear 42 are connected via the sync mechanism 47. . Thereby, the main shaft 41 and the main drive gear 42 rotate synchronously.

  In the present invention, the roller diameter and the number of rollers are not limited to those of each embodiment, and can be variously changed. Further, the tapered roller bearing according to the present invention can be used for automobile transmissions and automobile differentials as described above, and can also be used for applications other than automobile gear devices.

  As a first example, a bearing life test was conducted. FIG. 16 shows the result. The life test results under severe lubrication and overload conditions are shown. Comparative Example 1 is a conventional product having a roller coefficient of 0.86. Comparative Example 2 is the same as the example except that the outer ring and the cage are in contact with each other during operation with a steel plate cage.

  As is clear from the test results shown in FIG. 16, in Comparative Example 1, inner ring peeling occurred and the lifetime was 16.4 h. Comparative Example 2 stopped at a lifetime of 40.2 h due to an increase in torque due to cage wear. In the examples, no abnormality was observed even after 200 hours. In the case of the same test conditions, the calculated life according to JIS is 92.2h.

  As a second example, a torque measurement test using a vertical torque tester was performed. A tapered roller bearing (Example A) using the cage shown in FIG. 2 and a tapered roller bearing (Example B) using the cage shown in FIG. 3 were prepared. Moreover, as a comparative example, a tapered roller bearing (Comparative Example A) using a cage without a notch in the pocket and a tapered roller bearing (Comparative Example) using the cage shown in FIGS. 18 (A) and (B). B, C) were prepared. Each tapered roller bearing has an outer diameter of 100 mm, an inner diameter of 45 mm, and a width of 27.25 mm, and the portions other than the pocket notch are the same.

The test conditions for the tapered roller bearings of the example and the comparative example are as follows.
Axial load: 300kgf
Rotational speed: 300-2000 rpm (100 rpm pitch)
Lubrication condition: oil bath lubrication (lubricating oil: 75W-90)

  FIG. 17 shows the test results. The vertical axis of the graph in the figure represents the torque reduction rate with respect to the torque of Comparative Example A using a cage not having a notch in the pocket. Although the comparative example B in which a notch is provided in the central portion of the pocket portion and the comparative example C in which a notch is provided in the small annular portion and the large annular portion of the pocket have a torque reducing effect, the narrow width portion of the pocket Example A, in which a notch is provided in the column on the side, shows a torque reduction effect superior to those of these comparative examples, and a notch on the narrow side is provided with a notch in the small annular portion on the narrow side. In Example B in which the total area of each of these is wider than that on the wide side, a further excellent torque reduction effect is recognized.

  In addition, the torque reduction rate at 2000 rpm, which is the highest rotation speed of the test, was 9.5% in Example A and 11.5% in Example B, which was excellent even under high-speed rotation conditions such as in differentials and transmissions. A torque reduction effect can be obtained. In addition, the torque reduction rate in the rotational speed 2000rpm of the comparative example B and the comparative example C is 8.0% and 6.5%, respectively.

The tapered roller bearing of embodiment of this invention is shown, (A) is a cross-sectional view, (B) is a longitudinal cross-sectional view. FIG. 2 is a developed plan view of a cage in the tapered roller bearing of FIG. 1. It is an expanded top view similar to FIG. 2 which shows the modification of a holder | retainer. It is an expanded top view similar to FIG. 2 which shows another modification of a holder | retainer. It is the elements on larger scale of FIG.1 (B). (A) is a longitudinal sectional view of the tapered roller bearing before the cage moves in the axial direction, and (B) is a longitudinal sectional view of the tapered roller bearing after the cage moves. (A) is a schematic cross-sectional view of the tapered roller bearing at rest, (B) is a schematic cross-sectional view of the tapered roller bearing at the initial stage of rotation, and (C) is a schematic cross-sectional view of the rotating tapered roller bearing. It is a simplified view of the pocket of the cage. It is a simplified view of the pocket of the cage. It is a simplified view of the pocket of the cage. It is a simplified view of the pocket of the cage. It is sectional drawing of the differential of a common motor vehicle. It is sectional drawing of the transmission of a common motor vehicle. It is sectional drawing of the conventional tapered roller bearing which brought the cage | basket toward the outer ring | wheel side. It is a partial expanded sectional view of the tapered roller bearing which shows the prior art. It is a figure which shows the result of the lifetime test of a bearing. It is a graph which shows the result of a torque measurement test. A and B are the expansion | deployment top views of the holder | retainer which respectively show the prior art. It is a diagram showing the change of rigidity ratio and torque ratio when changing a roller pitch diameter (PCD) in a tapered roller bearing.

Explanation of symbols

1, 1a, 1b Tapered roller bearing 2 Inner ring 2a Raceway surface 2b Small brim 2c Large brim 3 Outer ring 3a Raceway surface 4 Tapered roller 5 Cage 6 Small ring part 7 Large ring part 8 Pillar part 9 Pocket 10a, 10b, 10c Notch 11 collar

Claims (8)

In a tapered roller bearing comprising an inner ring, an outer ring, a plurality of tapered rollers arranged to roll between the inner ring and the outer ring, and a cage that holds the tapered rollers at a predetermined circumferential interval,
The cage is composed of a small annular portion that is continuous on the small diameter end surface side of the tapered roller, a large annular portion that is continuous on the large diameter end surface side of the tapered roller, and a plurality of column portions that connect these annular portions, and adjacent column portions A trapezoidal pocket is formed with a narrow side on the small diameter side of the tapered roller and a wide side on the large diameter side, and a notch in the column on the narrow side of the pocket. Further, the roller coefficient exceeds 0.94, and the contact width of the roller on the pocket column surface is secured at least 10% of the pocket length with respect to the center position in the pocket axial direction on both the left and right sides. . The tapered roller bearing according to claim 1, wherein a notch is provided also in the small annular portion on the narrow side of the pocket. 3. The tapered roller bearing according to claim 1, wherein a notch is provided in at least a column portion on the wide side of the pocket. The tapered roller bearing according to claim 3, wherein the total area of the notches provided on the narrow side of the pocket is made larger than the total area of the notches provided on the wide side of the pocket. Provided radially inwardly facing the outer diameter surface of the small collar of the inner ring on the outer side in the axial direction of the small annular portion of the cage, between the inner diameter surface of the collar and the outer diameter surface of the small collar of the inner ring The tapered roller bearing according to any one of claims 1 to 4, wherein the upper limit of the clearance is 2.0% of the outer diameter of the small collar. At least the surface of the tapered roller is provided with an infinite number of minute concave recesses, the surface roughness parameter Ryni of the surface provided with the recesses is set to 0.4 μm ≦ Ryni ≦ 1.0 μm, and the Sk value is − The tapered roller bearing according to any one of claims 1 to 5, wherein the tapered roller bearing is 1.6 or less. The tapered roller bearing according to any one of claims 1 to 6, wherein a clearance exists between the outer diameter of the cage and the raceway surface of the outer ring when the cage is located at the center of the shaft. The tapered roller bearing according to any one of claims 1 to 7, wherein the tapered roller bearing supports a power transmission shaft of a self-propelled vehicle.

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