JP2008051274A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device obtaining lower torque without lowering rigidity of a bearing. <P>SOLUTION: The wheel bearing device comprises: a hub 22 having a hub flange 26 mounted with a wheel; an inner ring 32 having an inner race 34 fitted to the hub 22; a double-row outer ring 38 having a flange 40 to be fixed to a vehicle body 52 and double row outer races 44 formed on the inner peripheral face; tapered rollers 46 rollingly laid between the inner race 34 and each outer race 44; and a cage 48 for holding tapered rollers 46 in rows at predetermined circumferential spaces. The cage 48 consists of: a small annular portion ranging over the tapered rollers 46 at their small end face sides; a large annular portion ranging over the tapered rollers 46 at their large end face sides; and a plurality of columnar portions connecting the large annular portion to the small annular portion. Cutouts are provided in the columnar portions on the narrow sides of pockets formed between the adjacent columnar portions storing the tapered rollers 46 at their small diameter sides. The rollers each abut on the right and left sides of the pocket columnar face of the cage 48 in a range of 10% or more of the pocket length from the axially central position of the pocket. A roller coefficient is over 0.94. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device.

  In wheel bearing devices, a moment load is applied, so rolling bearings are often used in pairs. So-called hub bearings that are united with hubs include tapered roller bearings and double-row angular ball bearings. Double row rolling bearings are used.

  Tapered roller bearings consist of an inner ring with a small brim and a large brim 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 multiple inner rings 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 to the large diameter end surface side of the tapered roller. A base that consists of a large annular part and a plurality of pillars that connect these annular parts, and the pocket is the narrow side where the small diameter side of the tapered roller is stored, and the wide side is the part that stores the large diameter side What was formed in the shape is used.

  In a wheel bearing device having a tapered roller bearing, grease flows into the bearing from the small diameter side of the tapered roller, while grease also flows into the bearing from the outer diameter side and inner diameter side of the cage. Grease flowing in from the outer diameter side of the cage passes along the raceway surface (outer race) of the outer member serving as the outer ring to the larger diameter side of the tapered roller. The grease flowing in from the inner diameter side of the cage passes along the raceway surface (inner race) of the inner ring to the larger diameter side of the tapered roller.

Tapered roller bearings that are used in areas where lubricating oil such as grease flows in from the outside are provided with notches in the cage pockets, and flow is divided into the outer diameter side and the inner diameter side of the cage. There is one in which the lubricating oil passes through the notches to improve the flow of the lubricating oil inside the bearing (see Patent Documents 1 and 2). 22A, 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 into 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 in FIG. 22 (B), notches 10e are provided in the small annular portion 6 and the large annular portion 7 at both ends in the axial direction of the pocket 9 of the retainer 5 to hold it. 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 a value used for a comparative example in a torque measurement test described later.
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 above, in a tapered roller bearing in which the lubricating oil is divided into the outer diameter side and inner diameter side of the cage and flows into the bearing, torque increases as the proportion of lubricating oil flowing from the inner diameter side of the cage into the inner ring increases. It turns out that the loss 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 passes smoothly along the raceway surface to the large diameter side of the tapered roller because there is no obstacle on the inner diameter surface of the outer ring. The lubricating oil flowing 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 in the bearing increases, and this staying lubricating oil becomes a flow resistance against the bearing rotation and becomes a torque. Loss is considered to increase.

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

  In the tapered roller bearing 61 (FIG. 23) described in Patent Document 6, it is possible to increase the roller filling rate and reduce the maximum raceway surface pressure as compared with the type in which the cage and the outer ring do not contact. However, since the cage and the central part of the raceway surface are not in contact with each other, there is a demerit that the thickness of that part becomes thin. In other words, since the recess 64 is 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 during the assembly of the bearing 61. 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 to obtain the appropriate column strength and smooth rotation of the cage 72, the roller coefficient (roller filling rate) γ defined by the following formula usually needs to be 0.94 or less. (See Patent Document 4).
Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: number of rollers, DA: average roller diameter, PCD: roller pitch circle diameter. In FIG. 24, reference numeral 73 denotes a tapered roller, 74 denotes a column surface, 75 denotes an inner ring, and θ denotes a window angle.

  If an attempt is made to simply increase the roller filling rate with 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, in order to ensure the column strength, if the cage diameter is changed (increase the diameter) in the direction in which the clearance between the cage and the outer ring is reduced, as introduced in Patent Document 6, Wear at the outer ring contact area is accelerated, and drag torque may increase.

  An object of the present invention is to realize a reduction in torque in a wheel bearing device without reducing bearing rigidity.

  The wheel bearing device according to the present invention includes an outer member having two rows of outer races on the inner periphery, an inner member having two rows of outer races on the outer periphery, and an outer race and an inner race so as to roll freely. A tapered roller and a retainer for holding each row of tapered rollers at a predetermined interval in the circumferential direction, and the outer member has a flange portion for fixing to the vehicle body and has two rows on the inner circumferential surface. The outer member is formed of a hub having a flange for fixing the wheel and an inner ring fitted to the hub, and the retainer is a tapered roller. It is composed of a small annular part that is continuous on the small end face side, a large annular part that is continuous on the large end face side of the tapered roller, and a plurality of pillars that connect the large annular part and the small annular part. Narrow side column that houses the small diameter side of the tapered roller in the pocket A notch is provided, the roller contact width of the pocket pillar surface of the cage 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, and the roller coefficient exceeds 0.94. It is a feature.

  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 expressed by (number of rollers × roller average diameter) / (π × PCD). When the roller average diameter is constant, the larger the roller coefficient γ, It means that there are many rollers. In conventional typical tapered roller bearings with cages, the roller coefficient γ is normally 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. 25 shows the rigidity ratio (− ● −) and torque ratio (− ◯ −) when the roller pitch circle diameter (PCD) is changed in the tapered roller bearing. As shown in FIG. 25, when the PCD is reduced, the bearing torque is greatly reduced, but the bearing rigidity is not reduced so much as a result of calculating and confirming the amount of elastic deformation of the rollers. 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.

  By making the roller coefficient γ exceed 0.94, it is possible to reduce the roller PCD while increasing the number of rollers. As a result, 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 wheel bearing device of 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 wheel bearing device according to the first or second aspect, a notch is provided in at least the column portion on the wide side of the pocket.

  The invention according to claim 4 is the wheel bearing device according to claim 3, wherein the total area of the notches provided on the narrow side of the pocket is wider than the total area of the notches provided on the wide side of the pocket. To do.

  A fifth aspect of the present invention provides the wheel bearing device according to any one of the first to fourth aspects, wherein the small annular portion of the cage is radially outwardly opposed to the outer diameter surface of the small collar of the inner ring. 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 2.0% of the outer diameter dimension of the small collar.

  A sixth aspect of the present invention provides the wheel bearing device according to any one of the first to fifth aspects, wherein at least the surface of the tapered roller is provided with an infinite number of minute concave recesses, and the surface roughness of the surface on which the recesses are 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 bottom line of this extracted part is the vertical axis 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 and convex 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 amount of workpiece input, the type and size of the polishing tip, etc. By making the Sk value −1.6 or less, Lubricating oil can be held evenly in innumerable minute concave recesses.

  According to a seventh aspect of the present invention, in the wheel bearing device according to any one of the first to sixth aspects, there is a clearance between the outer diameter of the cage and the outer ring raceway surface in a state where the cage is located at the center of the shaft. It is a feature. By making the cage dimensions so that there is a clearance, there is little contact between the outer ring and the cage during bearing operation.

  The invention according to claim 8 is the wheel bearing device according to any one of claims 1 to 7, wherein one of the double row tapered rollers is replaced with a ball. This reduces the torque.

  The invention according to claim 9 is the wheel bearing device according to any one of claims 1 to 8, wherein the pitch circle diameter of the double row rolling elements is different between the inboard side and the outboard side. . Increased pitch circle diameter increases rigidity.

  The invention according to claim 10 is the wheel bearing device according to any one of claims 1 to 9, characterized in that the number of the rolling elements in the double row is different between the inboard side and the outboard side. Increasing the number of rolling elements increases rigidity and life.

  The invention according to claim 11 is the wheel bearing device according to any one of claims 1 to 7, 9 and 10, characterized in that the size of the double row rolling elements is different between the inboard side and the outboard side. It is.

  According to the present invention, the roller PCD can be reduced while increasing the number of rollers by making the roller coefficient γ exceed 0.94. As a result, 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, preventing surface-origin separation with extremely short life under severe lubrication conditions. be able to.

  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. As a result, the amount of lubricating oil reaching the collar along the raceway surface of the inner ring is reduced, the amount of lubricating oil staying inside the bearing is reduced, and torque loss due to the flow resistance of the lubricating oil is reduced.

  As in the invention of claim 2, by providing a notch also in the small annular portion on the narrow side of the pocket, the lubricating oil flowing from the inner diameter side of the cage to the inner ring side can be removed from the notch in the small annular portion. The amount of lubricating oil that escapes to the outer ring side and reaches the large brim along the raceway surface of the inner ring can be further reduced, and torque loss due to the flow resistance of the lubricating oil can be further reduced.

  As in the invention of claim 3, by providing the notch in at least the column portion on the wide side of the pocket, the tapered roller can be brought into sliding contact with the column portion in a well-balanced manner.

  As in the invention of claim 4, the raceway surface of the inner ring can also be obtained 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. As a result, the amount of lubricating oil that reaches the main flange can be reduced, and torque loss due to the flow resistance of the lubricating oil can be further reduced.

  According to the fifth aspect of the present invention, a radially inward flange is provided on the outer side in the ring direction of the small annular portion of the cage so as to face the outer diameter surface of the small collar of the inner ring. Lubricating oil that flows from the inner diameter side of the cage to the inner ring side by setting the clearance between the inner diameter surface of the collar and the outer diameter surface of the small collar of the inner ring to 2.0% or less of the outer diameter dimension of the small collar of the inner ring. The torque loss due to the flow resistance of the lubricating oil can be further reduced.

  As in the invention of claim 6, at least the surface of the tapered roller is randomly 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. Even if the amount of lubricating oil staying inside the bearing is reduced by keeping the lubricating oil evenly on the surface of the tapered roller by setting the value to 0 μm and the Sk value to −1.6 or less, the tapered roller and the inner and outer rings The contact portion can be sufficiently lubricated.

  As in the seventh aspect of the present invention, there is a clearance 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, so that contact between the outer ring and the cage is not caused during the bearing operation. Almost no occurrence occurs, and an increase in drag torque due to contact and wear can be suppressed.

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

  The embodiment 1 shown in FIG. 1 is a so-called 2.5 generation hub bearing in which the hub 22 and the double row rolling bearing are unitized. The double row rolling bearing is composed of an outer member corresponding to the bearing outer ring, an inner member corresponding to the bearing inner ring, and rolling elements interposed between the two members. Example 1 is an example using a double-row tapered roller bearing, and the rolling elements 46 are tapered rollers on both the outboard side and the inboard side, and the number and pitch circle diameter PCD are the same.

  The hub 22 has a shaft hole 24 that receives the stem portion 14 of the outer joint member 12 of the constant velocity universal joint. The hub 22 has a hub flange 26 on the outer periphery, and a hub bolt 30 for fixing a wheel disk (not shown) is implanted in the hub flange 26.

  The double row tapered roller bearing has a pair of inner ring 32, outer ring 38, tapered roller 46, and cage 48 as main components. The inner ring 32 constitutes an inner member, and the outer ring 38 constitutes an outer member. The inner ring 32 has an inner race 34 on the outer periphery, and is fitted to the outer peripheral surface of the cylindrical sleeve 28 of the hub 22. The inner ring 32 on the outboard side has the large collar 36 applied to the hub 22, and the inner ring 32 on the inboard side has the large collar 36 applied to the shoulder 20 of the outer joint member 12. The stem portion 14 of the outer joint member 12 is inserted into the shaft hole 24 of the hub 22, and the nut 22 is fastened to the male screw portion 16 at the shaft end, thereby fixing the hub 22 between the shoulder portion 20 of the outer joint member 12. .

  A flange 40 having a bolt hole 42 is formed on the outer periphery of the outer ring 38. The outer ring 38 is fixed to the vehicle body 52 by tightening the bolt 54 passed through the bolt hole 42. The outer ring 38 has two rows of tracks or outer races 44 on the inner periphery. Two rows of rolling elements, here tapered rollers 46, are interposed between the inner race 34 of the inner ring 32 and the outer race 44 of the outer ring 38. The rolling elements 46 in each row are held at predetermined intervals in the circumferential direction by a cage 48.

  In order to prevent leakage of the lubricant filled in the bearing and to prevent foreign matter from entering from the outside, a seal 50 is mounted between the opening portions at both ends of the outer ring 38 and the large collar 36 of the inner ring 32. is there.

  The second embodiment shown in FIG. 2 is an example of a so-called third generation hub bearing in which one of the two rows of inner races 34 is formed directly on the hub 22. In this case, the hub 22 and the inner ring 32 constitute an inner member.

  The third embodiment shown in FIG. 3 differs from the first embodiment in that the pitch circle diameter PCD of the double row rolling elements is different between the inboard side and the outboard side. Here, the pitch circle diameter PCD of the outboard side rolling element is made larger than the pitch circle diameter PCD of the inboard side rolling element. Increasing the outboard side increases rigidity.

  Example 4 shown in FIG. 4 differs from Example 2 in that the pitch circle diameter PCD of the double row rolling elements is different on the inboard side and the outboard side. Here, the pitch circle diameter PCD of the outboard side rolling element is made larger than the pitch circle diameter PCD of the inboard side rolling element. Increasing the outboard side increases rigidity.

  In the fifth embodiment shown in FIG. 5, the double row rolling elements 46 are different on the inboard side and the outboard side. Specifically, the rolling element 46 on the outboard side is changed to a ball to constitute an angular ball bearing. The fifth embodiment exemplifies the case of a driven wheel, the hub 22 is solid, and the axial end of the inner ring 32 is positioned by caulking the shaft end opposite to the hub flange 26 as indicated by reference numeral 20. It is.

  Example 6 shown in FIG. 6 is an example of a so-called third generation hub bearing. The difference from the fifth embodiment is that while the fifth embodiment uses a pair of separated inner rings 32, one of the two inner races 34, here, the inner race 34 on the outboard side is the hub. 22 is directly formed. The double row rolling elements 46 are balls on the outboard side and tapered rollers on the inboard side, and the number and pitch circle diameter PCD are the same. In this case, as in the second embodiment, the hub 22 and the inner ring 32 constitute an inner member.

  The seventh embodiment shown in FIG. 7 differs from the fifth embodiment in that the pitch circle diameter PCD of the double row rolling elements 46 is different between the inboard side and the outboard side. Here, the pitch circle diameter PCD of the outboard side rolling element 46 is larger than the pitch circle diameter PCD of the inboard side rolling element 46. Increasing the outboard side increases rigidity.

  The eighth embodiment shown in FIG. 8 is different from the sixth embodiment in that the pitch circle diameter PCD of the double row rolling elements 46 is different between the inboard side and the outboard side. Here, the pitch circle diameter PCD of the inboard side rolling element 46 is made larger than the pitch circle diameter PCD of the outboard side rolling element 46. Increasing the outboard side increases rigidity.

  In the above-described embodiments, the number of rolling elements is the same on the inboard side and the outboard side, but may be different on the inboard side and the outboard side. Increasing the number of rolling elements increases bearing life and rigidity. Alternatively, the size of the rolling elements may be different between the inboard side and the outboard side. Even if the bearing life is somewhat reduced, if it is necessary to increase the rigidity, the desired effect can be obtained by reducing the size of the rolling element and increasing the number of rolling elements.

  Next, the single row tapered roller bearing will be described as an example of the components of the double row rolling bearing constituting the wheel bearing device. A tapered roller bearing 1 shown in FIG. 9 shows a sub-assembly of one inner ring 2 and rolling elements, here a tapered roller 4. 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. 10, 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 are provided in each of the column portions 8 on both sides and cut from the outer diameter side to the inner diameter side. 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 smoothly lubricate the lubricating oil. As long as the passage is allowed, the shape and dimensions are arbitrary. Further, the window angle θ (see FIG. 24) of the column surface 5d is, for example, 25 ° to 50 °.

  11 and 12 show a modified example of the cage 5. In the modification shown in FIG. 11, 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. 12, the depth of each notch 10a in the narrow column 8 is 1.5 mm, which is deeper than each notch 10b in the wide column 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. 13, 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.

  In addition, although illustration is omitted, an infinite number of minute concave recesses are randomly provided on the entire surface of the tapered roller 4. The surface provided with the depression has a surface roughness parameter Ryni of 0.4 μm ≦ Ryni ≦ 1.0 μm and an Sk value of −1.6 or less.

  When the bearing rotates at high speed, as indicated by an arrow in FIG. 13, the lubricating oil is divided into the outer diameter side and the inner diameter side of the cage 5 from the small diameter side of the tapered roller 4 and flows into the bearing. The lubricating oil flowing into the outer ring 3 from the outer diameter side passes along the raceway surface 3a of the outer ring 3 to the larger diameter side of the tapered roller 4 and flows 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 , It passes through the notch 10a provided in the column 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 is extremely reduced, and the amount of the lubricating oil staying inside the bearing can be reduced.

  The cage 5 is integrally formed with a super engineering plastic such as PPS, PEEK, PA, PPA, PAI.

  In addition, the use of engineering plastics with excellent mechanical strength, oil resistance and heat resistance for the cage makes the cage lightweight, self-lubricating, and has a low friction coefficient. Combined with the effect of the lubricating oil intervening, it is possible to suppress the occurrence of wear due to contact with the outer ring. In addition, these resins are lighter and have a smaller coefficient of friction than steel plates, and are suitable for reducing torque loss and cage wear when starting bearings.

  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), poly 1,4-cyclohexanedimethylene terephthalate (PCT), polyamide 46 (PA46), polyamide 6T (PA6T), polyamide 9T (PA9T), polyamide 11,12 (PA11,12), fluororesin, polyphthalamide (PPA)

  Examples of cage materials include super engineering plastics such as PPS, PEEK, PA, PPA, and PAI. If necessary, these resin materials or other engineering plastics may be made of glass fiber or What mix | blended carbon fiber etc. may be used.

The tapered roller bearing 1 has a roller coefficient 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 circle diameter.

  By the way, the outer diameter of the cage 5 is changed from the state of FIG. 14A by moving the cage 5 to the axially smaller diameter side as shown by the arrow in FIG. 14B (FIG. 14B), and then FIG. As shown in FIG. 15C, when the outer ring 3 and the cage 5 are brought into contact with each other and the bearing 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 cage 5 is arranged at the center of the shaft, and the clearance between the cage 5 and the outer ring 3 when the cage 5 is close to the small diameter side as shown in FIG. However, 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 at the initial stage of operation (FIG. 15B), but are not in contact during operation (FIG. 15C). Can be suppressed.

  16 to 19 show the 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-dot chain 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 center 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 or damage due to stress concentration does not occur. 16 to 19, the notch 10a and the like are omitted.

  Specifically, in the case of FIG. 16, 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. 17, 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. 18, the roller contact is closer to the right side in FIG. 17, 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. 19 shows a case where the roller contact between the upper pocket column surface 5a and the lower pocket column surface 5a in the drawing is offset in the opposite direction. In either case, at least the pocket length from the pocket center position is shown. A width per roller of 10% or more is secured.

  FIG. 20 shows the result of the bearing life test. 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 FIG. 20, 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 increased torque due to cage wear. In the examples, no abnormality was observed even after 200 hours. Under the same test conditions, the calculated life according to JIS is 92.2h.

A torque measurement test was performed using a vertical torque tester. Tapered roller bearings using the cage shown in FIG. 10 and tapered roller bearings using the cage shown in FIG. 11 were prepared. These are referred to as Example A and Example B, respectively, for convenience. As a comparative example, a tapered roller bearing using a cage not having a notch in a pocket (Comparative Example A) and a tapered roller bearing using a cage shown in FIGS. 22A and 22B (Comparative Example) 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 are as follows.
Axial load: 2942N
Rotational speed: 300-2000r / min (100r / min pitch)
Lubrication condition: oil bath lubrication (lubricating oil: 75W-90)

  FIG. 21 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. The comparative example B in which a notch is provided in the central portion of the pocket column and the comparative example C in which a notch is provided in the small annular portion and the large annular portion of the pocket also show a torque reducing effect, but the narrow width portion of the pocket Example A with a notch 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 on the small annular part on the narrow side. In Example B, in which the total area is larger than that on the wide side, a further excellent torque reduction effect is recognized.

  The torque reduction rate at 2000 r / min, which is the maximum rotation speed of the test, was 9.5% in Example A and 11.5% in Example B. Conditions for use at high speed rotation in wheel bearing devices and the like However, an excellent torque reduction effect can be obtained. In addition, the torque reduction rate in the rotational speed 2000r / min of the comparative example B and the comparative example C is 8.0% and 6.5%, respectively.

Vertical sectional view of the wheel bearing device of Example 1 The longitudinal cross-sectional view of the wheel bearing apparatus of Example 2 Vertical sectional view of the wheel bearing device of Example 3 Vertical sectional view of the wheel bearing device of Example 4 Vertical sectional view of the wheel bearing device of Example 5 Vertical sectional view of the wheel bearing device of Example 6 Vertical sectional view of the wheel bearing device of Example 7 Vertical sectional view of the wheel bearing device of Example 8 (A) is a cross-sectional view of the sub-assembly of the inner ring and the tapered roller, and (B) is a vertical cross-sectional view. 9 is a developed plan view of the cage in FIG. An expanded plan view similar to FIG. 10 showing a modified example of the cage Fig. 10 is a developed plan view similar to Fig. 10 showing another modified example of the cage. Partial enlarged view of FIG. (A) is a longitudinal sectional view before the cage is moved in the axial direction, and (B) is a longitudinal sectional view after the cage is moved. (A) is a schematic cross-sectional view at rest, (B) is a schematic cross-sectional view at the beginning of rotation, and (C) is a schematic cross-sectional view during rotation. Simplified cage pocket Simplified cage pocket Simplified cage pocket Simplified cage pocket Diagram showing results of bearing life test Graph showing results of torque measurement test (A), (B) is a developed plan view of a cage showing the prior art, respectively. Sectional view of a conventional tapered roller bearing with the cage moved toward the outer ring Partial enlarged sectional view of a tapered roller bearing showing conventional technology Diagram showing changes in rigidity ratio and torque ratio when changing the roller pitch circle diameter (PCD) in tapered roller bearings

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 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 annular part 7 Large annular part 8 Pillar part 9 Pocket 10a, 10b, 10c Notch 11 Collar 12 Outside Joint member 14 Stem portion 16 Male thread portion 18 Nut 20 Shoulder portion 22 Hub 24 Shaft hole 26 Flange 28 Sleeve 30 Hub bolt 32 Inner ring 34 Inner race 36 Large collar 38 Outer ring 40 Flange 42 Bolt hole 44 Outer race 46 Tapered roller 47 Bolt 48 Cage 50 Seal 52 Car body 54 Bolt

Claims (11)

An outer member having two rows of outer races on the inner periphery, an inner member having two rows of inner races on the outer periphery, a tapered roller interposed between the outer race and the inner race so as to roll freely, A cage for holding the tapered rollers at predetermined intervals in the circumferential direction;
The outer member is a double-row outer ring having a flange portion for fixing to the vehicle body and forming two rows of outer races on the inner peripheral surface;
The inner member includes a hub having a flange for fixing the wheel and an inner ring fitted to the hub;
The cage is composed of a small annular portion that is continuous on the small end surface side of the tapered roller, a large annular portion that is continuous on the large end surface side of the tapered roller, and a plurality of column portions that connect the large annular portion and the small annular portion. A notch is provided in the narrow side column part that houses the small diameter side of the tapered roller of the pocket formed between the column parts, and the contact width of the roller on the pocket column surface of the cage is the pocket axial direction on both the left and right sides. 10% or more of the pocket length is secured relative to the center position,
Wheel bearing device with roller coefficient exceeding 0.94.   The wheel bearing device according to claim 1, wherein a notch is provided also in a small annular portion on a narrow side of the pocket.   The wheel bearing device according to claim 1 or 2, wherein a notch is provided in at least a column portion on the wide side of the pocket.   4. The wheel bearing device according to claim 3, wherein a total area of notches provided on the narrow side of the pocket is wider than a total area of notches provided on the wide side of the pocket.   A radially inward flange is provided on the outer side in the axial direction of the small annular portion of the cage so as to face the outer diameter surface of the small collar of the inner ring, and the inner diameter surface of the collar and the outer diameter surface of the inner ring small collar The wheel bearing device 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 brim.   An infinite number of minute concave recesses are provided at least on the surface of the tapered roller, the surface roughness parameter Ryni of the surface provided with these recesses is 0.4 μm ≦ Ryni ≦ 1.0 μm, and the Sk value is −1. 6. The wheel bearing device according to claim 1, wherein the wheel bearing device is 6 or less.   The wheel bearing device according to any one of claims 1 to 6, wherein a clearance exists between the outer diameter of the cage and the outer ring raceway surface in a state where the cage is located at the center of the shaft.   The wheel bearing device according to claim 1, wherein one of the double-row tapered rollers is replaced with a ball.   The wheel bearing device according to any one of claims 1 to 8, wherein PCDs of the double row rolling elements are different on an inboard side and an outboard side.   The wheel bearing device according to any one of claims 1 to 9, wherein the number of rolling elements in the double row is different between the inboard side and the outboard side.   The wheel bearing device according to any one of claims 1 to 7, 9, and 10, wherein the size of the double row rolling elements is different between an inboard side and an outboard side.

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