JP2007127217A - Tapered roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce torque without degrading the rigidity of a bearing. <P>SOLUTION: A tapered roller bearing 1 comprises, an inner ring 2, an outer ring 3, a plurality of tapered rollers 4, and a cage 5. A coefficient γ of roller exceeds 0.94. The cage 5 is constituted of an annular part 6 contiguous to a small end face side of the tapered roller 4, an annular part 7 contiguous to a large end face side of the tapered roller 4, and a plurality of columns 8 connecting the annular parts. Tapered faces 8a in contact with a rolling face of each tapered roller 4 are formed on both sides of an inner diameter face of the column part 8, and the length L in a lateral direction of the tapered faces is 5% or more and less than 11% of an average diameter of the tapered rollers 4. An outer diameter diameter of the holder 5 is set to such dimension that it does not come into contact with the outer ring 3 in a neutral condition and comes into contact with the outer ring 3 when moving in the radial direction. <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 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.

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 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.

  This invention solves the problem by reducing the roller pitch diameter (PCD) without decreasing or increasing the number of rollers. FIG. 8 shows the rigidity ratio (-●-) and torque ratio (-o-) when the PCD is changed in the tapered roller bearing. As a result of calculating and confirming the amount of elastic deformation of the rollers, as shown in FIG. 8, it was found that if the PCD is decreased, the torque of the bearing is significantly reduced, but the bearing rigidity is not significantly 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 of the present invention comprises an inner ring, an outer ring, a plurality of tapered rollers interposed between the inner ring and the outer ring, and a cage that holds the tapered rollers in pockets, and has a roller coefficient γ of 0. .94, the retainer includes 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 the annular portions. And a tapered surface 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 not less than 5% of the average diameter of the roller. %, The cage is in non-contact with the outer ring in the neutral state, and is in contact with the outer ring when moved in the radial direction.

  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.

  Since the cage is in non-contact with the outer ring in the neutral state and is brought into contact with the outer ring when moved in the radial direction, drag, torque increase and wear due to contact can be suppressed, which is advantageous for low torque. It is.

  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.

  Each of the above tapered roller bearings is suitable for supporting a power transmission shaft of a self-propelled vehicle (claim 3).

  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.

  Furthermore, since the maximum surface pressure of the raceway surface of the tapered roller bearing can be reduced, it is possible to prevent surface-origin separation with an extremely short life under severe lubrication 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. 3. 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.

  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. 9, reference numerals 73, 74, and 75 denote tapered rollers, column surfaces, and inner rings, respectively, and reference sign θ denotes a window angle. If an attempt is made to simply increase the roller filling rate while keeping the pocket size of the cage 72 as it is, the column 72a of the cage 72 becomes thin, and sufficient column strength cannot be ensured. On the other hand, in order to secure the column strength, changing the cage diameter in a direction that reduces the clearance between the cage and the outer ring, that is, increasing the diameter size, promotes wear at the outer ring contact portion of the cage and drags. This can cause an increase in torque. Therefore, as described below, the cage 5 is preferably not in contact with the outer ring 3 in the neutral state and is in contact with the outer ring 3 when moved in the radial direction.

  The outer diameter of the cage 5 is determined by moving the cage 5 from the state of FIG. 1 (A) to the small axial side as shown by the arrow in FIG. 1 (B), and then FIG. 2 (A). When the outer ring 3 and the cage 5 are brought into contact with each other and the bearing rotates and the cage 5 is centered as shown in FIG. 2C, the cage 5 and the outer ring 3 are moved. Is set to a dimension such that there is no contact with a predetermined clearance around the entire circumference. In other words, such a dimension means that the clearance between the retainer 5 and the outer ring 3 when the retainer 5 is arranged at the center of the shaft and the retainer 5 is close to the small diameter side as shown in FIG. Although it exists, the outer ring 3 and the cage 5 are in contact with each other when the cage 5 is moved in the radial direction from the axial center. As a result, the outer ring 3 and the cage 5 are in contact in the initial stage of operation (FIG. 2B), but are not in contact during operation (FIG. 2C). Can be suppressed. In the case of an iron plate cage, it is necessary to spread the bottom and caulk, but in the case of a resin cage, it is not necessary, and it is easy to ensure the required dimensional accuracy. Here, “bottom opening” means that when the cage 5 incorporating the roller is assembled to the inner ring, the diameter of the column portion on the small diameter side of the cage 5 is greatly expanded so that the roller can get over the small brim of the inner ring. . “Caulking operation” refers to pushing the column portion of the small-diameter portion of the cage 5 greatly expanded as described above by pushing it with a mold from the outside.

  As shown in FIG. 4A, 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. The angle formed by the column surface 8a, that is, the window angle θ is, for example, 25 ° to 50 °.

  As shown in FIG. 4B, 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.

  A tapered roller bearing (Example) using a cage in which the length L of the tapered surface shown in FIG. 4B 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. 5 shows the results of the torque measurement test, and the vertical axis of the graph in FIG. 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.

  The cage 5 is made of an iron plate and can be used without worrying about material deterioration (oil resistance) due to immersion in oil. The cage 5 may be integrally formed with a super engineering plastic such as PPS, PEEK, PA, PPA, or PAI instead of the steel plate. 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)

  FIG. 6 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. 7 shows a schematic configuration of an automobile transmission that can use the tapered roller bearing of the present invention. 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.

  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 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 (A) is a sectional view of the cage before moving in the axial direction, (B) is a sectional view of the cage after moving. (A) is a side view of the cage of the tapered roller bearing at rest, (B) is a side view of the cage of the tapered roller bearing at the initial stage of rotation, and (C) is a side view of the cage of the tapered roller bearing during rotation. 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 Partial enlarged sectional view of a tapered roller bearing showing conventional technology

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 (column surface)
9 pockets

Claims (3)

An inner ring, an outer ring, a plurality of tapered rollers interposed between the inner ring and the outer ring, and a cage for holding the tapered rollers in pockets,
Roller coefficient γ exceeds 0.94,
The cage includes an annular portion that is continuous on the small end face side of the tapered roller, an annular portion that is continuous on the large end face side of the tapered roller, and a plurality of pillar portions that connect the annular portions. A tapered surface in contact with the rolling surface of the roller is formed on both sides of the inner diameter surface of the 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;
A tapered roller bearing in which the cage is in non-contact with the outer ring in a neutral state and contacts the outer ring when moved in the radial direction.   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, which supports a power transmission shaft of a self-propelled vehicle.

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