JP4994638B2 - Tapered roller bearing - Google Patents

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.

  The tapered roller bearing holds an inner ring having a raceway surface on the outer diameter surface, an outer ring having a raceway surface on the inner diameter surface, a plurality of tapered rollers interposed between the raceways of the inner ring and the outer ring, and these rollers. And a retainer. The cage has an annular portion that is continuous on the small end surface side of the tapered roller, an annular portion that is continuous on the large end surface side of the roller, and a plurality of column portions that connect these annular portions to each other. A pocket for storing rollers between the parts is defined. In such a cage, tapered surfaces are provided on both sides of the inner diameter surface of the column portion in contact with the rolling surface of the roller so that contact wrinkles do not occur on the rolling surface of the roller. Conventionally, the length L in the width direction of the tapered surface is generally 11 to 20% of the average diameter D of the rollers.

Tapered roller bearings that support power transmission shafts such as differentials and transmissions of self-propelled vehicles are used in a state where a part of them is immersed in an oil bath. It becomes a state. In such a roller bearing used in an oil bath lubrication state, the lubricating oil that enters the wedge space formed by these surfaces is also formed between the rolling surface of the roller and the tapered surface of the inner diameter surface of the column portion of the cage. Lubricated.
JP 09-096352 A JP-A-11-210765 JP 2003-343552 A

  Conventional roller bearings in which the length L of the tapered portion of the cage is 11 to 20% of the average diameter D of the roller are relatively large wedges between the rolling surface of the roller and the tapered portion of the column. A space is formed, and a large amount of lubricating oil enters the wedge space. Since the amount of lubricating oil entering the interface between the rolling surface of the roller and the tapered surface of the cage from this wedge space is limited, when a large amount of lubricating oil enters the wedge space in this way, There is a problem that there is no escape space and there is resistance to rotation of the bearing, and torque loss increases. Further, in such a roller bearing in which the lubricating oil flows into the bearing, the flow resistance of the lubricating oil with respect to the rotation of the cage also causes a torque loss that cannot be ignored.

  Therefore, it is necessary to reduce torque loss due to flow resistance of the lubricating oil in the 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, with the conventional torque reduction technique (see Patent Documents 1 to 3), it is possible to reduce the torque without reducing the rated load, but the bearing rigidity is somewhat reduced.

  The main object of the present invention is to realize a low torque without reducing the bearing rigidity.

  This invention solves the problem by reducing the roller pitch diameter (PCD) without decreasing or increasing the number of rollers. FIG. 13 shows the rigidity ratio (-●-) and torque ratio (-o-) when PCD is changed in a tapered roller bearing. As a result of calculating and confirming the amount of elastic deformation of the rollers, as shown in FIG. 13, it was found that if the PCD is reduced, the torque of the bearing is greatly reduced, but the rigidity of the bearing is not much reduced. Therefore, the torque can be reduced without reducing the rigidity by reducing the PCD while decreasing or increasing the number of rollers.

The tapered roller bearing of the present invention comprises 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. By reducing the roller pitch diameter, the roller coefficient γ exceeds 0.94, and at least the surface of the tapered roller is provided with an infinite number of minute concave recesses, and the surface roughness parameter Ryni of the surface provided with the recesses is provided. Is within the range of 0.4 μm ≦ Ryni ≦ 1.0 μm, and the Sk value is −1.6 or less, and the cage includes an annular portion continuous on one end side of the roller, It consists of an annular part connected on the other end side and a plurality of column parts connecting the both annular parts, and tapered surfaces that are in contact with the rolling surfaces of the rollers are formed on both sides of the inner diameter surface of the column part. Yes (except for those with bent column edges) The length of the tapered surface in the width direction is 5% or more and less than 11% of the average diameter of the rollers.

  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 normally set to 0.94 or less, whereas the roller coefficient γ exceeds 0.94. This means that the filling rate and thus the bearing rigidity is high.

  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 − By setting it to 1.6 or less, even if the lubricant is uniformly held on the surface of the tapered roller and the amount of lubricant remaining in the bearing is reduced, the contact portion between the tapered roller and the inner and outer rings is sufficiently lubricated. be able to.

  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 portion is the vertical magnification of the roughness curve. (ISO 4287: 1997). The parameter Sk indicates the degree of distortion (skewness) of the roughness curve (ISO 4287: 1997), and is a statistic that serves as a guideline for knowing the asymmetry of the uneven distribution. In a symmetric distribution such as a Gaussian distribution, the Sk value is 0. When the concave and convex portions are deleted, a negative value is obtained. Conversely, when a concave portion is 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, and the like. By setting the Sk value to −1.6 or less in both the width direction and the circumferential direction, the minute concave recess becomes an oil reservoir, and the lubricating oil can be held evenly. Therefore, even when compressed, there is little oil leakage in the sliding direction and the right-angle direction, the oil film formation is excellent, the oil film formation state is good, and the surface damage is suppressed as much as possible.

By making the length dimension in the width direction of the taper surface of the column portion of the cage in contact with the roller rolling surface to be less than 11%, preferably 9% or less of the average diameter of the roller, the roller rolling surface and the taper as infrequently large wedge space is formed between the surface, the amount of lubricant entering the wedge space less, and in so that reduce torque loss due to escape of the lubricating oil is eliminated. The reason why the width direction of the length of the tapered surface more than 5% of the average diameter of the rollers is less than 5% the width of the resilient contact area is tapered surfaces between the outer diameter surface and the tape over tapered surface of the roller It is because there is a possibility of becoming larger.

According to a second aspect of the present invention, in the tapered roller bearing of the first aspect, the thickness dimension of the column portion is 5% or more and less than 17% of the average diameter of the roller. Thereby, the thickness of the column portion can be reduced, the flow resistance of the lubricating oil against the rotation of the cage can be reduced, and the torque loss can be further reduced. The reason why the thickness of the column portion is set to 5% or more of the average diameter of the rollers is that if the thickness is less than 5%, sufficient rigidity of the cage cannot be secured.

The invention according to claim 3 is the tapered roller bearing according to claim 1 or 2, wherein the surface roughness parameter Rymax of the surface provided with the recess is in the range of 0.4 to 1.0 μm. It is. The parameter Rymax is the maximum value of the maximum height for each reference length (ISO 4287: 1997).

  According to a fourth aspect of the present invention, in the tapered roller bearing according to any one of the first to third aspects, when the surface roughness of the surface provided with the recess is indicated by a parameter Rqni, the axial surface roughness Rqni (L) and the circle The ratio value Rqni (L) / Rqni (C) to the circumferential surface roughness Rqni (C) is 1.0 or less. The parameter Rqni is the square root of the value obtained by integrating the square of the height deviation from the roughness center line to the roughness curve in the section of the measurement length and averaging it, and is also called the root mean square. Rqni is obtained by numerical calculation from the cross-sectional curve and roughness curve recorded in an enlarged manner, and measured by moving the stylus of the roughness meter in the width direction and the circumferential direction.

  According to a fifth aspect of the present invention, in the tapered roller bearing according to the first to fourth aspects, the window angle of the pocket of the cage is 55 ° or more and 80 ° or less. The window angle is an angle formed by a surface of the column portion that is in contact with the rolling surface of the roller. The reason why the window angle is set to 55 ° or more is to ensure a good contact state with the roller. This is because there is a risk that smooth rotation cannot be obtained even with this resin material. In a normal cage, the window angle is 25 ° to 50 °.

  According to a sixth aspect of the present invention, in the tapered roller bearing according to any one of the first to fifth aspects, the cage is formed of an engineering plastic excellent in mechanical strength, oil resistance and heat resistance. Is. 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 coefficient of friction is smaller than that of steel plate cages. Therefore, in combination with the effect of the lubricating oil present in the bearing, it becomes 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 therefore suitable for reducing torque loss and cage wear at the start of the bearing. As the cage material, super engineering plastics such as PPS, PEEK, PA, PPA, PAI are used, and if necessary, these resin materials or other engineering plastics are made of glass fiber or carbon fiber for strength enhancement. You may use what mix | blended.

  Each of the above tapered roller bearings is suitable for supporting a power transmission shaft of a self-propelled vehicle (claim 7).

According to the present invention, torque loss can be reduced without reducing rigidity. That is, the tapered roller bearings of the present invention, time by factor γ is to set the Ru exceed 0.94, without reducing the number of rollers, or while increasing, it is possible to reduce the pitch circle diameter (PCD) around , It is possible to prevent a decrease in rigidity. Moreover, the roller by greater to Rukoto than the coefficient gamma 0.94, not only the load capacitance is up, it is possible to reduce the maximum surface pressure on the raceway surface, at the very short life under severe lubrication conditions Surface origin peeling can be prevented.

  Further, the length dimension in the width direction of the taper surface of the retainer column portion in contact with the roller rolling surface is set to be 5% or more and less than 11% of the average diameter of the roller, so that the roller rolling surface and the taper surface A very large wedge space is not formed between the two and the amount of lubricating oil entering the wedge space is reduced. Therefore, the torque loss due to the absence of the escape space for the lubricating oil is reduced, and the reduction in torque can be promoted from this aspect as well.

  Furthermore, by providing an infinite number of indentations with a small concave shape at least on the surface of the tapered roller, the oil film forming ability is improved, and a long life is achieved even under extremely thin oil film conditions under low viscosity and dilute lubrication. Obtainable. In particular, by setting the surface roughness parameter Ryni of the surface with the indentation within the range of 0.4 μm ≦ Ryni ≦ 1.0 μm and keeping it smaller than before, it is possible to prevent oil film breakage even under lean lubrication. Thus, a longer life can be obtained even under conditions where the oil film thickness is extremely thin compared to conventional products. As for the Sk value, −1.6 or less is a range advantageous for oil film formation in terms of the shape and distribution of the surface recess depending on the processing conditions.

Embodiments of the present invention will be described below with reference to the drawings. First, the overall configuration will be described with reference to FIG. 2. The tapered roller bearing 1 includes an inner ring 2, an outer ring 3, a tapered roller 4, and a cage 5 as main components. The inner ring 2 has a conical raceway surface 2a formed on the outer periphery, and the outer ring 3 has a conical raceway surface 3a formed on the inner periphery. 4 a plurality of tapered rollers between the raceway surface 3a of the raceway surface 2 a and the outer ring 3 of the inner ring 2 are interposed rollably. Each tapered roller 4 is accommodated in a pocket formed in the cage 5, and axial movement is restricted 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 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 represented by the following formula.
Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: number of rollers, DA: roller average diameter, PCD: roller pitch circle diameter.

  For comparison, referring to FIG. 3 and referring to the prior art, the tapered roller bearing shown in FIG. 3 is a typical tapered roller bearing with a cage in which the cage is spaced from the outer ring. In order to avoid the contact between 71 and the cage 72, to secure the column width of the cage 72 and to obtain the appropriate column strength and smooth rotation of the cage 72, a roller coefficient γ (filling of rollers) is usually used. The ratio is designed to be 0.94 or less. In FIG. 3, reference numerals 73, 74, and 75 denote a tapered roller, a column surface, and an inner ring, respectively, and reference sign θ denotes a window angle.

  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.

  As shown in FIG. 1A, the cage 5 includes an annular portion 6 that is continuous on the small end face side of the tapered roller 4, an annular portion 7 that is continuous on the large end face side of the tapered roller 4, and these annular portions 6. , 7 are connected to each other, and a trapezoidal pocket 9 is defined between the adjacent column portions 8.

As shown in FIG. 1B, tapered surfaces 8 a that are in contact with the rolling surfaces of the tapered rollers 4 are formed on both sides of the inner diameter surface of the column portion 8. The length L in the width direction of the tapered surface 8a is desirably set to 5% or more and less than 11%, for example, 7% of the average diameter D of the tapered rollers 4. With such a configuration, a very large wedge space is not formed between the rolling surface of the tapered roller 4 and the tapered surface 8a. The thickness dimension T of the column portion 8 is preferably set to 5% or more and less than 17%, for example, 10% of the average diameter D of the tapered rollers 4. By setting it as such a structure, the flow resistance of the lubricating oil with respect to rotation of the holder | retainer 5 can be restrained small.

  Referring to FIGS. 4 and 5, the angle formed by the surface 8a of the column 8 that contacts the roller rolling surface, that is, the window angle θ will be described. The lower limit window angle θmin is 55 ° (FIG. 4), and the upper limit window angle. θmax is 80 ° (FIG. 5). The window angle is at most about 50 ° in a conventional tapered roller bearing with a cage (FIG. 3) in which the cage is spaced from the outer ring. The reason why the lower limit window angle θmin is set to 55 ° is to ensure a good contact state with the roller, and when the window angle is less than 55 °, the contact state with the roller is deteriorated. That is, when the window angle is 55 ° or more, the cage strength is secured and γ> 0.94 and a good contact state can be secured. Further, the upper limit window angle θmax is set to 80 ° because if it is larger than this, the pressing force in the radial direction increases, and there is a risk that smooth rotation cannot be obtained even with a self-lubricating resin material. It is.

  FIG. 6 shows the result of the bearing life test. In the figure, “Comparative Example 1” in the “Bearing” column is a typical conventional tapered roller bearing (see FIG. 3) in which the cage and the outer ring are separated. “Comparative Example 2” is a tapered roller bearing in which only the roller coefficient γ is γ> 0.94 in the tapered roller bearing of the present invention compared to the conventional product. “Example” is a tapered roller bearing of the present invention in which the roller coefficient γ is set to γ> 0.94 and the window angle is in the range of 55 ° to 80 °. The dimensions (unit: mm) were all φ45 × φ81 × 16, and the number of rollers was 24 for “Comparative Example 1” and 27 for “Comparative Example 2” and “Example”. The test was performed under severe lubrication (oil film parameter Λ = 0.2) and overload conditions. As is clear from FIG. 4, “Comparative Example 2” has a lifetime that is at least twice that of “Comparative Example 1”. Further, the bearing of the “Example” has a roller coefficient of 0.96 which is the same as that of “Comparative Example 2”, but the life time is about five times or more that of “Comparative Example 2”.

  The cage 5 can be integrally formed with a super engineering plastic such as PPS, PEEK, PA, PPA, or PAI. If necessary, a glass fiber or carbon fiber blended with these resin materials or other engineering plastics may be used for strength enhancement. 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)

Next, a modified embodiment shown in FIGS. 7 and 8 will be described. The tapered roller bearing 1 shown in FIG. 7 is formed by forming a protruding portion 8b that protrudes toward the outer ring raceway surface on the outer diameter surface of the column portion 8 of the cage 5 integrally formed of engineering plastic. is there. The rest is the same as the cage 5 described above. As shown in FIG. 8, the protruding portion 8b has a cross-sectional contour shape in the transverse direction of the column portion 8 having an arc shape. This arc-shaped curvature radius R ₂ is smaller than the outer ring raceway radius R ₁ . This is because a good wedge-shaped oil film is formed between the protrusion 8b and the outer ring raceway surface. Desirably, the radius of curvature R ₂ of the protrusion is formed to be about 70 to 90% of the outer ring raceway radius R ₁ . If it is less than 70%, the opening angle of the wedge-shaped oil film becomes too large, and the dynamic pressure decreases. If it exceeds 90%, the inlet angle of the wedge-shaped oil film becomes too small, and the dynamic pressure similarly decreases.

Further, the lateral width W ₂ of the protrusion 8b is desirably 50% or more of the lateral width W ₁ of the column part 8 (W ₂ ≧ 0.5W ₁ ). This is because if it is less than 50%, it is not possible to secure a sufficient height of the protruding portion 8b for forming a rust-like oil film. Since the outer ring raceway surface radius R ₁ continuously changes to a small diameter side from the large diameter side, large radius of curvature of the radius of curvature R ₂ of the projecting portion 8b also accordingly large diameter side annular section 7 R ₂ To a small radius of curvature R ₂ of the small-diameter side annular portion 6.

Since the tapered roller bearing 1 of FIGS. 7 and 8 is configured as described above , when the bearing 1 rotates and the cage 5 starts to rotate, the space between the outer ring raceway surface and the protrusion 8b of the cage 5 is increased. A wedge-shaped oil film is formed. Since this wedge-shaped oil film generates a dynamic pressure substantially proportional to the rotational speed of the bearing 1, even if the pitch circle diameter (PCD) of the cage 5 is made larger than that in the prior art and close to the outer raceway surface, the bearing 1 It is possible to rotate without causing great wear or torque loss, and it is possible to increase the number of rollers without difficulty.

  FIG. 9 shows an example of the configuration of an automobile differential that can use the tapered roller bearing of the present invention. In this differential, a drive pinion 22 arranged in a differential case 21 connected to a propeller shaft (not shown) meshes with a ring gear 24 attached to a differential gear case 23, and a pinion gear attached to the inside of the differential gear case 23. 25 is engaged with a side gear 26 coupled to a drive shaft (not shown) inserted into the differential gear case 23 from the left and right, and transmits the driving force of the engine from the propeller shaft to the left and right drive shafts. 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.

  Lubricating oil is stored in the differential case 21 and sealed with seal members 27a, 27b, and 27c. The tapered roller bearings 1a and 1b rotate in a state where the lower part is immersed in a lubricating oil bath. Lubricating oil flows into the bearing.

  A tapered roller bearing (Example) using a retainer in which the length dimension L of the tapered surface shown in FIG. 1B is 7% of the average diameter D of the tapered roller, and the tapered surface length dimension L are tapered. A tapered roller bearing (comparative example) using a conventional cage having an average diameter D of 13% of rollers was prepared. The dimensions of the tapered roller bearing were all set to an outer diameter of 100 mm, an inner diameter of 45 mm, and a width of 27.25 mm. Further, the thickness T of the column portion of the cage was set to 13% of the average diameter D of the tapered roller in the example and 17% in the comparative example.

About the tapered roller bearing of an Example and a comparative example, the torque measurement test using the vertical torque tester was done. The test conditions are as follows.
・ Axial load: 300kgf
・ Rotation speed: 300-2000 rpm (100 rpm pitch)
・ Lubrication conditions: Oil bath lubrication (lubricating oil: 75W-90)

  FIG. 10 shows the results of the torque measurement test, and the vertical axis of the graph in FIG. 10 represents the torque reduction rate of the example of the embodiment relative to the torque of the comparative example. In the example in which the length L of the tapered surface is as small as 7% of the average diameter D of the tapered roller, a remarkable torque reduction effect is recognized from low speed rotation to high speed rotation, and even at the maximum rotation speed of 2000 rpm of the test. A torque reduction rate of 12.0% is obtained. The torque reduction effect of this embodiment includes the effect of reducing the flow resistance of the lubricating oil against the rotation of the cage by reducing the thickness dimension T of the column portion.

  In the tapered roller bearing according to each of the above-described embodiments, a minute concave recess is formed on at least one of the rolling surface and end surface of the tapered roller and the raceway surface of the inner and outer rings (and the large flange surface for the inner ring of the tapered roller bearing). The surface is randomly roughened by countless numbers. This minute rough surface has a surface roughness parameter Rqni of a surface provided with a depression within a range of 0.4 μm ≦ Rqni ≦ 1.0 μm, and an Sk value of −1.6 or less, preferably −4.9. It is the range of -1.6. Further, the surface roughness parameter Rymax of the surface provided with the depression is 0.4 to 1.0. Further, when the surface roughness is obtained in the axial direction and the circumferential direction of each surface and displayed by the parameter Rqni, the ratio of the axial surface roughness Rqni (L) to the circumferential surface roughness Rqni (C) The value Rqni (L) / Rqni (C) is 1.0 or less. As the surface processing for obtaining such a fine rough surface, a desired finished surface can be obtained by special barrel polishing, but a shot or the like may be used.

  In the case of a tapered roller bearing, as can be understood from FIG. 2 (B), the rolling surface of the tapered roller 4 is in rolling contact with the races of the inner ring 2 and the outer ring 3 during operation, and the large end surface of the tapered roller 4 is the inner ring 2. In sliding contact with the inner surface of the large collar 2c. Therefore, in the case of the tapered roller 4, an infinite number of minute concave recesses may be randomly formed on the large end face in addition to the rolling face. Similarly, in the case of the inner ring 2, an infinite number of minute concave recesses may be formed on the inner surface of the large brim 2c in addition to the raceway surface.

The measurement method and conditions of the parameters Ryni, Rymax, Sk, Rqni are exemplified as follows. When measuring the surface properties represented by these parameters for components such as rolling elements and rolling rings of rolling bearings, a single measured value can be relied on as a representative value. Should be measured.
Parameter calculation standard: JIS B 0601: 1994 (Surfcom JIS 1994)
Measurement length: 5λ
Cut-off type: Gaussian Measurement magnification: × 10000
Measurement speed: 0.30 mm / s
Measurement location: Roller center measurement number: 2
Measuring device: Surface roughness measuring device Surfcom 1400A (Tokyo Seimitsu Co., Ltd.)

  Next, the conventional tapered roller bearings A and B (comparative example) in which the rolling surface of the tapered roller is finished to a smooth surface, and a bearing in which an infinite number of minute concave recesses are formed on the rolling surface of the tapered roller. A life test conducted on C to E (comparative example) and bearings F and G (examples) will be described (see Table 1). The bearings A to G used are tapered roller bearings having an outer diameter of 81 mm and an inner diameter of 45 mm. In addition, the rolling surfaces of the rollers in the bearings A and B of the comparative example are processed by super finishing (superfinishing) after grinding, and are not subjected to indentation processing. The rolling surfaces of the rollers C to E of the comparative examples and the bearings F and G of the examples are formed with a myriad of indentations of minute concave shapes randomly by barrel polishing special processing. For Rqni (L / C), the roller bearings C to G are 1.0 or less, and the roller bearings A and B are about 1.0.

  A peeling test was performed using a two-cylinder testing machine shown in FIG. 11, and the metal contact rate was evaluated. In the figure, a driving side cylinder 32 (D cylinder: Driver) and a driven side cylinder 34 (F cylinder: Follower) are attached to one end of each rotating shaft, and the two rotating shafts 36 and 38 are respectively connected via pulleys 40. Can be driven by separate motors. The shaft 36 on the D cylinder 32 side was driven by a motor, and the F cylinder 34 was free-rolled to follow the D cylinder 32. For the F cylinder 34, two types of comparative examples and examples were prepared for the surface treatment. Details of the test conditions are shown in Table 2.

  Comparison data of metal contact ratio is shown in FIG. In this figure, the horizontal axis represents the elapsed time, the vertical axis represents the metal contact rate, FIG. 12A shows the metal contact rate of the rolling contact surface of the roller in the comparative example bearing, and FIG. 12B shows the bearing of the example. The metal contact ratios of the rolling surfaces of the rollers are shown respectively. Comparing these figures, it can be clearly confirmed that the metal contact ratio is improved in the embodiment as compared with the comparative example. In other words, the oil film formation rate (= 100% −metal contact rate) is about 10% at the start of operation and 2 at the end of the test (after 2 hours) in the bearing of the example compared to the bearing of the comparative example. % Improvement.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

(A) is an expansion | deployment top view of the holder | retainer which shows embodiment of this invention , (B) is a BB arrow line view of FIG. 1 (A) . (A) is a cross-sectional view of a tapered roller bearing showing an embodiment of the present invention , (B) is a longitudinal cross-sectional view of the tapered roller bearing of FIG. 2 (A) . It is a partial expanded sectional view of the tapered roller bearing which shows the prior art . It is a partial expanded sectional view of the tapered roller bearing whose window angle is a lower limit . It is a partial expanded sectional view of the tapered roller bearing whose window angle is an upper limit . It is a figure which shows the result of the lifetime test of a bearing . It is a fragmentary sectional view of the tapered roller bearing which concerns on the modification of this invention . It is sectional drawing of the pillar part of the holder | retainer of FIG. It is sectional drawing of a common motor vehicle differential . It is a graph which shows the result of a torque measurement test . It is the whole 2 cylinder testing machine schematic . (A) is a graph which shows the metal contact rate of a comparative example , (B) is a graph which shows the metal contact rate of an Example . Rigidity ratio in the case of changing the pitch circle diameter (PCD) around the tapered roller bearing (- ● -) and the torque ratio (- ○ -) is a diagram showing the change of.

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 4 Tapered roller 5 Cage 6 Annular part (roller small end face side)
7 Annular part (Roller large end face side)
8 Column 8a Tapered surface 8b Protrusion 9 Pocket

Claims (7)

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,
By reducing the roller pitch diameter, the roller coefficient γ exceeds 0.94,
At least the surface of the tapered roller is provided with an infinite number of minute concave recesses, and the surface roughness parameter Ryni of the surface provided with the recesses is within a range of 0.4 μm ≦ Ryni ≦ 1.0 μm, and Sk The value is -1.6 or less,
The cage is composed of an annular portion that is continuous on one end side of the roller, an annular portion that is continuous on the other end side of the roller, and a plurality of column portions that connect the annular portions, Tapered surfaces that are in contact with the rolling surface of the roller are formed on both sides of the inner diameter surface of the column portion (excluding those in which the edge of the column portion is bent), and the length dimension in the width direction of the tapered surface is Tapered roller bearings that are 5% or more and less than 11% of the average diameter of the rollers.   The tapered roller bearing according to claim 1, wherein a thickness dimension of the column portion is 5% or more and less than 17% of an average diameter of the roller.   The tapered roller bearing according to claim 1 or 2, wherein a surface roughness parameter Rymax of the surface provided with the recess is in a range of 0.4 to 1.0 µm.   When the surface roughness of the surface provided with the depression is represented by the parameter Rqni, the ratio value Rqni (L) / Rqni (R) of the axial surface roughness Rqni (L) and the circumferential surface roughness Rqni (C) The tapered roller bearing according to any one of claims 1 to 3, wherein C) is 1.0 or less.   The tapered roller bearing according to any one of claims 1 to 4, wherein a window angle of the pocket of the cage is 55 ° or more and 80 ° or less.   The tapered roller bearing according to any one of claims 1 to 5, wherein the cage is formed of an engineering plastic excellent in mechanical strength, oil resistance and heat resistance.   The tapered roller bearing according to any one of claims 1 to 6, which supports a power transmission shaft of a self-propelled vehicle.

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