JP2007132469A - Tapered roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tapered roller bearing having a low torque without degrading the rigidity thereof. <P>SOLUTION: The tapered roller bearing comprises an inner ring 2 having a raceway surface on the outer diameter surface, an outer ring 3 having a raceway surface on the inner diameter surface, a plurality of tapered rollers 4 interposed between the raceway surface of the inner ring and the raceway surface of the outer ring, and a cage 5 holding the tapered rollers in pockets. A coefficient γ of rollers exceeds 0.94. The cage 5 comprises an annular part 6 arranged continuously on the small end face side of the tapered rollers, an annular part 7 arranged continuously on the large end face side of the tapered rollers, and a plurality of column parts 8 connecting both annular parts to each other. Tapered surfaces 8a in contact with the rolling surfaces of the rollers 4 are formed on both sides of the inner diameter surfaces of the column parts 8. The length dimension L of the tapered surfaces in the lateral direction is 5 to less than 11% of the averaged diameter of the tapered rollers 4. (The circumferential length of the rollers on the pitch circle of the rollers)-(the roller diameter×the number of the rollers) is less than the roller diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tapered roller bearing and can be used, for example, as a bearing that supports a power transmission shaft of a self-propelled vehicle.

  Tapered roller bearings consist of 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 raceway surfaces of the inner ring and the outer ring, and these tapered rollers. It consists of a cage to hold. 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 tapered roller, and a plurality of column portions that connect these annular portions to each other. A pocket for storing the tapered roller is defined between the 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.

Tapered 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, and oil bath lubrication uses the oil in the oil bath as the lubricating oil as it rotates. 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 cage column. 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.

  The present invention solves the problem by reducing the roller pitch circle diameter (PCD) without reducing or increasing the number of rollers. FIG. 11 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 roller, as shown in FIG. 11, when the PCD is reduced, the torque of the bearing is greatly reduced, but the knowledge that the bearing rigidity is not lowered much is obtained. 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 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 intervenes between the raceway surface of the inner ring and the raceway surface of the outer ring. And a retainer for retaining the roller in a pocket, the retainer being connected to one end of the roller, and an annular portion connected to the other end of the roller. And a plurality of pillars connecting the two annular parts, taper surfaces in contact with the rolling surfaces of the rollers are formed on both sides of the inner diameter surface of the pillars, and the length of the taper faces in the width direction. The dimension is 5% or more and less than 11% of the average diameter of the roller, and (circumferential length on the pitch circle) − (roller diameter × number of rollers) <roller diameter. In other words, the difference between the circumferential length on the roller pitch circle and the product of the roller diameter and number is smaller than the roller diameter.

  (Length in circumferential direction on pitch circle) − (Roller diameter × Number of rollers) <Roller diameter makes it possible to reduce the roller pitch circle diameter (PCD) without decreasing or increasing the number of rollers. it can.

  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 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 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.

  According to a third aspect of the present invention, in the tapered roller bearing of the second 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 fourth aspect of the present invention, in the tapered roller bearing according to any one of the first to third 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 coefficient of friction than steel plates, they are advantageous in reducing torque loss and cage wear at the start of the bearing.

  Each of the above tapered roller bearings is suitable for supporting a power transmission shaft of a self-propelled vehicle (claim 5).

  According to the present invention, torque loss can be reduced without reducing rigidity. That is, the tapered roller bearing according to the present invention has a roller pitch that does not reduce or increase the number of rollers by (circumferential length on the pitch circle) − (roller diameter × number of rollers) <roller diameter. The circle diameter (PCD) can be reduced. 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, according to the present invention, not only the load capacity is increased, but also the maximum surface pressure of the raceway surface can be reduced, so that it is possible to prevent surface origin separation with an extremely short life under severe lubrication conditions. it can.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, 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.

Here, the tapered roller bearing 1 satisfies the relationship of (circumferential length on the pitch circle) − (roller diameter × number of rollers) <roller diameter. Incidentally, a conventional typical tapered roller bearing with a cage, as shown in FIG. 12, avoids the contact between the outer ring 71 and the cage 72 and secures the column width of the cage 72 to appropriately hold the cage. In order to obtain the column strength and smooth rotation of the vessel 72, the roller coefficient γ defined by the following equation is usually designed to be 0.94 or less.
Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: number of rollers, DA: roller average diameter, PCD: roller pitch circle diameter.
In FIG. 12, 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. 2A, 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. 2B, tapered surfaces 8 a that contact the rolling of the tapered roller 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.

  A tapered roller bearing (Example) using a cage in which the length L of the tapered surface shown in FIG. 2B is 7% of the average diameter D of the tapered roller, and the length L of the tapered surface is 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. 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.

  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). In a conventional tapered roller bearing with a cage in which the cage is separated from the outer ring (see FIG. 12), the window angle is at most about 50 °. Here, by setting the window angle to be larger, the difference between the length on the roller pitch circle and the product of the roller diameter and the number of rollers is smaller than the roller diameter [(circumferential length on the pitch circle Sa)-(Roller diameter x Number of rollers) <Roller diameter]. 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 roller strength on the roller pitch circle can be made less than (roller diameter / number of rollers) and a good contact state can be secured while securing the cage strength. . 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 "Bearing" column of the figure, "Comparative Example 1" is a typical conventional tapered roller bearing (see FIG. 12) in which the cage and the outer ring are separated. “Comparative example 2” is a tapered roller bearing in which only the relationship of (circumferential length on the pitch circle) − (roller diameter × number of rollers) <roller diameter is satisfied among the tapered roller bearings of the present invention. In the “example”, the relationship of (circumferential length on the pitch circle) − (roller diameter × number of rollers) <roller diameter is established, and the window angle is 55 ° to 80 °. It is a tapered roller bearing of the 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 modification shown in FIG. 7 will be described. 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. 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 width W ₂ of the projecting portion 8b is desirably 50% or more of the width W ₁ of the pillar portions _{5c (W 2 ≧ 0.5W 1)} . This is because if it is less than 50%, a sufficient height of the protrusion 8b for forming a rust-like oil film cannot be secured. 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 FIG. 7 is configured as described above, when the bearing 1 rotates and the cage 5 starts to rotate, a wedge shape is formed between the outer ring raceway surface and the protrusion 8b of the cage 5. An 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 a schematic configuration of an automobile differential that can use the tapered roller bearing of the present invention. The differential serves to transmit engine driving force from a propeller shaft (not shown) to left and right drive shafts (not shown). A drive pinion 22 disposed in the differential case 21 is connected to a differential gear case 23. The pinion gear 25 attached to the inside of the differential gear case 23 meshes with the side gear 26 coupled to the drive shaft inserted from the left and right. In this differential, a drive pinion 22 that is a power transmission shaft and a differential gear case 23 are supported by a pair of tapered roller bearings 1a and 1b, respectively. 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. 10 shows a schematic configuration of an automobile transmission that can use the tapered roller bearing according to the present invention. Automobile transmissions (main transmissions) are broadly classified into manual types and automatic types. Depending on the vehicle drive system, front wheel drive (FWD) transaxle, rear wheel drive (RWD) transmission, and four wheel drive (4WD) ) Transfer (sub-transmission). These shift the driving force from the engine and transmit it to the drive shaft or the like.

  This transmission is of a synchronous mesh type, and the left side in FIG. 10 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 synchro mechanism 47 is arranged close to 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 attached to 41, a synchronizer ring 51 slidably mounted on the outer periphery (cone portion) of the clutch gear 46, a pressing pin 52 for elastically pressing the synchronizer key 49 against the inner periphery of the sleeve 48, and And a spring 53.

  In the state shown in FIG. 10, 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 from the state shown in the figure by the operation of the selector, the synchronizer key 49 is moved to the left side in the axial direction accordingly. Press against the inclined surface. 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) is an expanded plan view of a cage showing an embodiment of the present invention, (B) is a view taken along the line BB in FIG. 1 (A). (A) is a transverse sectional view of a tapered roller bearing showing an embodiment of the present invention, (B) is a longitudinal 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 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 circle diameter (PCD) in tapered roller bearings Partial enlarged sectional view of a conventional tapered roller bearing

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Tapered roller bearing 2 Inner ring 2a Raceway surface 2b Small brim 2c Large brim 3 Outer ring 3a Raceway surface 4 Tapered roller 5 Cage 6 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 (5)

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 tapered rollers interposed between the raceway surface of the inner ring and the raceway surface of the outer ring, and the tapered roller The retainer is held in a pocket, and the retainer connects the annular portion connected on the small end face side of the tapered roller, the annular portion connected on the large end face side of the tapered roller, and the both annular portions. And a tapered surface that is in contact with the rolling surface of the roller is 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 the average diameter of the roller. Tapered roller bearings with 5% or more and less than 11%, and (circumferential length on pitch circle) − (roller diameter × number of rollers) <roller diameter. 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 window angle of a pocket of the cage is 55 ° or more and 80 ° or less. The tapered roller bearing according to any one of claims 1 to 3, wherein the cage is made 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 4, which supports a power transmission shaft of a self-propelled vehicle.

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