JP2007120650A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To substantialize low torque without deteriorating the rigidity of a bearing. <P>SOLUTION: The roller bearing comprises an inner ring 2, an outer ring 3, a plurality of 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 rollers 4 thereon at specified intervals. The roller factor is set to exceed 0.94. The retainer 5 comprises a small annular part 6 continuously formed on the small end face side of the rollers 4, a large annular part 7 continuously formed on the large end face side of the rollers 4, and a plurality of column parts 8 connecting the large and small annular parts 6, 7 to each other. Tapered faces 8a contacting a rolling face of the rollers 4 are formed on both sides of the inner-diameter face of the column parts 8. A length L of the tapered face 8a in the width direction is 5% or more and less than 11% of the average diameter of the rollers 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a roller bearing suitable for use in a portion where lubricating oil flows from the outside.

  A roller bearing such as a cylindrical roller taper or a tapered roller bearing includes an inner ring having a raceway surface on an outer diameter surface, an outer ring having a raceway surface on an inner diameter surface, and a plurality of rollers interposed between the raceway surfaces of the inner ring and the outer ring. And a cage for holding these rollers. The cage includes 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. A pocket for storing the rollers is defined between the matching pillars. 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.

Roller bearings that support power transmission shafts such as differentials and transmissions of self-propelled vehicles are used in a state where some are immersed in an oil bath. It becomes. 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. 12 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. 12, it was found that if the PCD is reduced, the torque of the bearing is greatly reduced, but the bearing rigidity 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 roller bearing according to the present invention includes an inner ring having a raceway surface on an outer diameter surface, an outer ring having a raceway surface on an inner diameter surface, and a plurality of intermediate rings interposed between the raceway surface of the inner ring and the raceway surface of the outer ring. A roller and a retainer for holding the roller in a pocket, the roller coefficient γ exceeds 0.94, and the retainer is connected to one end side of the roller, and the other end of the roller. It consists of an annular portion that is continuous on the end side, and a plurality of column portions that connect the annular portions, 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 portion, The length dimension in the width direction of the tapered surface is 5% or more and less than 11% of the average diameter of the roller.

  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.

  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 By not forming a very large wedge space with the surface, the amount of lubricating oil entering the wedge space is reduced, and torque loss due to the absence of the escape space for lubricating oil can be reduced. The length of the taper surface in the width direction is set to 5% or more of the average diameter of the roller. When the length is less than 5%, the elastic contact region between the outer surface of the roller and the taper surface is larger than the width of the taper surface. This is because there is a possibility of increasing.

  According to a second aspect of the present invention, in the roller bearing of the first aspect, a thickness dimension of the column portion is 5% or more and less than 17% of an 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 dimension of the column portion is set to 5% or more of the average value of the rollers is that if 5%, the rigidity of the cage cannot be secured sufficiently.

  The roller bearing is suitable for a tapered roller bearing in which the roller is a tapered roller.

  According to a fourth aspect of the present invention, in the roller bearing of the third aspect, 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 fifth aspect of the present invention, in the roller bearing according to any one of the first to fourth aspects, the cage is formed of an engineering plastic excellent in mechanical strength, oil resistance and heat resistance. It is. By using a resin material for the cage, the cage weight is lighter, self-lubricating, and the coefficient of friction is smaller than the steel plate cage. Together, it becomes possible to suppress the occurrence of wear due to contact with the outer ring. Since these resins are lighter and have a smaller friction coefficient than steel plates, they are suitable for reducing torque loss and cage wear when starting the bearing.

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

  According to the present invention, torque loss can be reduced without reducing rigidity. That is, the roller bearing of the present invention can reduce the roller pitch diameter (PCD) while reducing or increasing the number of rollers by setting the roller coefficient γ so as not to exceed 0.94. Lower torque is achieved without lowering rigidity. Moreover, by suppressing the roller coefficient γ to be smaller than 0.94, not only the load capacity is increased, but also the maximum surface pressure of the raceway surface can be reduced, so that the surface with an extremely short life under severe lubrication conditions Starting point peeling can be prevented.

  Furthermore, the length dimension in the width direction of the taper surface of the pillar portion of the cage 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. 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.

  Embodiments of the present invention will be described below with reference to the drawings. Here, a case of a tapered roller bearing will be described as an example. As shown in FIG. 2, the tapered roller bearing 1 includes an inner ring 2, an outer ring 3, a tapered roller 3, and a cage 4 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. 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 roll freely. Each tapered roller 4 is accommodated in a pocket of the cage 5, and axial movement is restricted by the small collar 2 b and the large collar 2 c of the inner ring 2.

The tapered roller bearing 1 has a roller coefficient γ> 0.94. The roller coefficient (roller filling rate) γ is expressed 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.
Note that the conventional typical tapered roller bearing with cage retains the column width of the cage 72 while avoiding contact between the outer ring 71 and the cage 72 as shown in FIG. In order to obtain the column strength and smooth rotation, the roller coefficient γ is usually designed to be 0.94 or less. In FIG. 6, reference numerals 73, 74, and 75 denote a tapered roller, a column surface, and an inner ring, respectively, and reference sign θ represents a window angle.

  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 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 about 50 ° at most in a conventional tapered roller bearing with a cage (FIG. 6) 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. 7 shows the result of the bearing life test. In the same figure, “Comparative Example 1” in the “Bearing” column is a typical conventional tapered roller bearing in which the cage and the outer ring are separated (see FIG. 6), and “Comparative Example 2” is the tapered roller bearing of the present invention. Of these, a tapered roller bearing in which only the roller coefficient γ is γ> 0.94 with respect to the conventional product, “Example” has a roller coefficient γ> γ> 0.94, and the window angle ranges from 55 ° to 80 °. This is a tapered roller bearing of the present invention. The test was conducted under severe lubrication and overload conditions. As is clear from the figure, “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 dimensions of “Comparative Example 1”, “Comparative Example 2”, and “Example” are φ45 × φ81 × 16 (unit mm), and the number of rollers is 24 (“Comparative Example 1”) and 27 (“Comparative Example”). 2 ”,“ Example ”), and the oil film parameter Λ = 0.2.

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

Next, a modified embodiment of the present invention will be described with reference to FIGS. The tapered roller bearing 1 shown in FIG. 1 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 that is integrally formed of engineering plastic. is there. The rest is the same as the cage 5 described above. As shown in FIG. 9, the projecting 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 for the purpose of forming a good wedge-shaped oil film 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 portion 5c (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. 8 and 9 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 protruding portion 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. 10 shows a differential of an automobile using the tapered roller bearing 1 described above. 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.

  FIG. 11 shows an example of the configuration of a vehicle transmission. This transmission is of a synchronous mesh type, and the left side of the figure is the engine side and the right side is the drive wheel side. A tapered roller bearing 43 is disposed 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 formed directly 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 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, and a main shaft. A hub 50 engaged and connected to the outer periphery of 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 pressed against 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 increases. When the rotational speeds of the two are synchronized, the sleeve 48 further moves to the left in the axial direction, engages 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.

  A tapered roller bearing (Example) using a retainer in which the length L of the tapered surface shown in FIG. 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. 3 shows the results of the torque measurement test, and the vertical axis of the graph in FIG. 3 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.

  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. For example, the embodiment has been described by taking the case of a tapered roller bearing as an example, but the present invention can also be applied to a cylindrical roller bearing or a barrel roller bearing.

(A) is a development top view of a cage showing an embodiment of this invention. (B) is a view taken along the line BB in 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). Graph showing results of torque measurement test Partial enlarged sectional view of tapered roller bearing with lower window angle Partial enlarged sectional view of a tapered roller bearing with an upper window angle Partial enlarged sectional view of a conventional tapered roller bearing Diagram showing results of bearing life test Partial sectional view of tapered roller bearing according to a modification of the present invention Sectional drawing of the pillar part of the cage | basket of FIG. Cross section of a typical automobile differential Cross section of a typical automobile transmission Diagram showing changes in stiffness ratio (-●-) and torque ratio (-○-) when changing the roller pitch diameter (PCD) in tapered roller bearings

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 end face side)
7 Annular part (Roller large end face side)
8 Column 8a Tapered surface 8b Protrusion 9 Pocket

Claims (6)

An inner ring having a raceway surface on an outer diameter surface, an outer ring having a raceway surface on an inner diameter surface, a plurality of rollers interposed between the raceway surface of the inner ring and the raceway surface of the outer ring, and the rollers in pockets And a cage to hold
Roller coefficient γ exceeds 0.94,
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 in contact with the rolling surface of the roller are formed on both sides of the inner diameter surface of the column portion, and the length dimension in the width direction of the tapered surface is 5% or more and less than 11% of the average diameter of the roller Roller bearing.   2. The 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 roller bearing according to claim 1, wherein the roller bearing is a tapered roller bearing in which the roller is a tapered roller.   The roller bearing according to claim 3, wherein a window angle of the pocket of the cage is 55 ° or more and 80 ° or less.   The roller bearing according to any one of claims 1 to 4, wherein the cage is formed of an engineering plastic excellent in mechanical strength, oil resistance and heat resistance. The roller bearing according to any one of claims 1 to 5, which supports a power transmission shaft of a self-propelled vehicle.

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