JP4786482B2 - Tapered roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conical roller bearing which allows an improvement in fretting resistance and bearing service life. <P>SOLUTION: A conical roller bearing is employed for an idler portion of a transmission for an automobile which switches between an idling state in which an outer ring 23 idles with respect to an inner ring 22 and a shift state in which the outer ring 23 synchronously rotates with the inner ring 22. In a neutral state of a retainer 25, the retainer 25 and outer ring 23 are brought into a non-contact state to create a clearance. A part of the retainer 25 is brought into contact with the outer ring 23 through the radial movement of the retainer 25 from the neutral state. The coefficient &gamma; of roller exceeds 0.94. A window angle of a pocket in the retainer 25 is set between 55&deg; and 80&deg;. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a tapered roller bearing, and more particularly to a tapered roller bearing used for an idler portion of a transmission for an automobile.

  As an example of this transmission, there is a synchronous mesh transmission shown in FIG. In this transmission, a main shaft 1 and a sub shaft 2 arranged in parallel at a predetermined interval are rotatably supported by a transmission case (not shown), and the main shaft 1 is interlocked with an output shaft (drive wheel side), The shaft 2 is linked to the input shaft (engine side).

  A countershaft gear 3 is integrally provided on the countershaft 2 described above, and a mainshaft gear 6 (a bearing outer ring and a bearing outer ring) that is always meshed with the countershaft gear 3 via a bearing inner ring 4 and needle rollers 5 on the main shaft 1. (Combined use) is rotatably mounted. Spline teeth 7 and a cone 8 are formed on one side of the main shaft gear 6, and a hub 9 is disposed in the vicinity of the end surface of the cone 8 and is integrally connected to the main shaft 1. A synchro mechanism 10 is interposed between the hub 9 and the cone 8, and a sleeve 11 is splined to the outer periphery of the hub 9 so as to be movable in the axial direction.

  In the state shown in the figure, the main shaft gear 6 rotates idly with respect to the main shaft 1 under the rotation of the countershaft gear 3. On the other hand, when the sleeve 11 moves to the right side in the axial direction from the state shown in the figure, the sleeve 11 is engaged with the spline teeth 7 of the main shaft gear 6 via the synchro mechanism 10, and the space between the main shaft gear 6 and the main shaft 1 is increased. Connected. Thereby, the rotation of the countershaft gear 3 is decelerated by the main shaft gear 6 at a predetermined speed ratio and transmitted to the main shaft 1. During this speed change, the main shaft gear 6 rotates in synchronization with the main shaft 1 and the bearing inner ring 4.

  By the way, at the time of the speed change described above, the main shaft gear 6 and the bearing inner ring 4 rotate synchronously, so that the needle rollers 5 that are rolling elements are stopped on the raceway surfaces of the both 4 and 6. On the other hand, when a vibration from the outside acts repeatedly, a minute slip occurs repeatedly between the needle roller 5 and the raceway surface, and a phenomenon called fretting in which the contact surface wears due to the relative repeated minute slip is a problem. It may become.

  Therefore, in order to suppress the above-mentioned fretting, the raceway surface of the main shaft gear 6 and the bearing inner ring 4 and the rolling surface of the needle roller 5 are subjected to Parker treatment (phosphate coating treatment), and the needle roller 5 and the raceway surface. Some have reduced frictional resistance. However, the parker-treated film may be worn out, and a good fretting suppression effect over a long period cannot be expected.

Further, conventionally, there are those provided with uneven circumferential distribution of the tapered rollers, weight unbalance in the circumferential direction of the cage for holding the tapered rollers, unbalance means due to unequal weight of the tapered rollers, etc. ( Patent Document 1). That is, by shifting the center of gravity of the cage from the center of rotation, a moment of inertia is used to cause relative rotation from a stopped state.
Japanese Unexamined Patent Publication No. 2000-193069

  However, in order to make the pockets of the cage non-uniform pitches, it is necessary to reduce the number of rollers as compared to the uniform pitch, which is not preferable because the bearing life is shortened and the bearing life is shortened. For this reason, a tapered roller bearing used for an idler portion of a transmission is required to have both improved fretting resistance and improved bearing life.

The present invention is, in view of the above problems, to provide a tapered roller bearing which can improve the resistance Frette fin grayed resistance and bearing life.

The tapered roller bearing of the present invention has a tapered roller held in a cage at equal circumferential intervals, and is switched to an idle state in which an outer ring rotates idly with respect to an inner ring and a shift state in which an outer ring rotates synchronously with the inner ring. In tapered roller bearings that are used in the idler part of the cylinder and are subjected to repeated external loads, the cage and outer ring are not in contact with each other when the cage is in the neutral state. as can contact the outer ring portion of the cage by the movement of, along with increasing the PCD, coefficient γ exceeds 0.94 rollers, and a window angle of a pocket of the cage with a less than 80 ° 55 ° or more, The surface pressure relief structure is in a stopped state, and the surface of the tapered roller is further subjected to MoS2 treatment. Here, the roller coefficient γ is defined by the following equation. Moreover, the window angle of a pocket means the angle which the surface which contact | connects the rolling surface of a roller of a pillar part makes.

Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: Number of rollers, DA: Roller average diameter, PCD: Roller pitch circle diameter

  In the neutral state of the cage, the cage and the outer ring are not in contact with each other, and a clearance is generated. By moving the cage in the radial direction from this neutral state, a part of the cage is brought into contact with the outer ring, so that the PCD Furthermore, since the roller coefficient γ exceeds 0.94, the column width of the cage can be increased while avoiding contact between the outer ring and the cage in the neutral state.

  Moreover, the favorable contact state of a holder | retainer and a tapered roller is securable by making the window angle of the holder | retainer 55 or more. Moreover, by setting the window angle of the cage to 80 ° or less, the pressing force in the radial direction is not increased, and smooth rotation can be obtained. In a normal cage, the window angle is 25 ° to 50 °.

  It is preferable to perform MoS2 treatment on the surface of the tapered roller. Here, the MoS2 treatment is a treatment in which the surface layer portion (base material surface layer portion) of the member to be coated is coated with MoS2 (molybdenum disulfide). For example, the base material surface layer portion is melted by heat to dissolve molybdenum disulfide. Incorporated into the base material and recrystallized. For this reason, this coating layer is strong against abrasion, hardly peeled off, and has an excellent effect of reducing sliding resistance. Thus, by subjecting the surface of the tapered roller to MoS2, the frictional resistance between the tapered roller and the rolling surfaces of the outer ring and the inner ring can be reduced.

  In the tapered roller bearing of the present invention, in the neutral state, it is possible to increase the column width of the cage while avoiding contact between the outer ring and the cage, so that the total load capacity can be increased without changing the bearing dimensions. It becomes possible to raise to the level of a roller bearing (bearing which does not use a cage). Thereby, the contact surface pressure can be reduced, the surface pressure in the stopped state is relaxed, and the fretting resistance is improved. In addition, the cage and the tapered roller can ensure a good contact state, and the tapered roller can be smoothly rotated.

In particular, by performing MoS2 treatment on the surface of the tapered rollers, it is possible to prevent more stable generation of Frette fin grayed, it is possible to bearing life improvement by load capacity improvement, anti Frette fin grayed property Both improvement and bearing life can be improved.

  An embodiment of a tapered roller bearing according to the present invention will be described with reference to FIGS.

  FIG. 1 shows an automobile transmission (synchronous meshing transmission) using a tapered roller bearing of the present invention. The main shaft and the sub shaft are arranged in parallel at predetermined intervals, the main shaft is interlocked with the output shaft on the drive wheel side, and the main shaft is interlocked with the input shaft on the engine side. That is, the countershaft gear is provided on the countershaft, and the main shaft gear constituting the outer ring 23 of the tapered roller bearing A is meshed with the countershaft gear.

  That is, the tapered roller bearing A includes a pair of inner rings 22 having a conical raceway surface 22a, an outer ring 23 having a pair of conical raceway surfaces 23a, a raceway surface 22a of the inner ring 22, and a raceway surface 23a of the outer ring 23. And a plurality of tapered rollers 24 arranged so as to be freely rotatable, and a cage 25 for holding the tapered rollers 24 at equal intervals around the circumference. The inner ring 22 has a small brim 22b on the small diameter side and a large brim 22c on the large diameter side.

  Further, the outer ring 23 is provided with a tooth portion 27 that meshes with the countershaft gear of the subshaft on the outer peripheral surface thereof, and a tooth portion 28 that meshes with a clutch gear (not shown) is provided at an axial end portion thereof. . Although not shown, a synchro mechanism is disposed in the vicinity of the clutch gear.

  That is, at the neutral time, the outer ring (main shaft gear) 23 idles with respect to the inner ring 22, but at the time of speed change by the outer ring (main shaft gear) 23, the outer ring (main shaft gear) 23 is connected to the inner ring 22 and the main shaft by interlocking via a synchronization mechanism. Synchronously rotate.

  The cage 25 includes a small-diameter-side annular portion 25a, a large-diameter-side annular portion 25b, and a plurality of column portions 25c that connect the small-diameter-side annular portion 25a and the large-diameter-side annular portion 25b in the axial direction. The window pushing angle (window angle) θ (see FIG. 5) of the column surface 25d is 55 ° or more and 80 ° or less.

  Further, the roller coefficient γ is set to exceed 0.94. Here, the roller coefficient γ is defined by the following equation. Further, the window angle θ of the pocket (between adjacent column portions along the circumferential direction) 18 refers to an angle formed by a surface of the column portion that contacts the rolling surface of the tapered roller 24.

Roller coefficient γ = (Z · DA) / (π · PCD)
Here, Z: Number of rollers, DA: Roller average diameter, PCD: Roller pitch circle diameter

  The cage 25 is formed, for example, by press-molding a metal plate into a truncated trapezoidal shape and then punching out each pocket 18. As the metal plate, rolled steel plate such as cold rolled steel plate (SPC) and hot rolled mild steel plate (SPH), spring steel, and the like can be used. In the case of a cold rolled steel plate (SPC) or a hot rolled mild steel plate (SPH), it is preferable to subject the surface to surface hardening treatment such as carbonitriding treatment or gas soft nitriding treatment.

  Here, carbonitriding is a method in which nitriding is performed at the same time as carburizing, in which carbon C and nitrogen N are diffused. For example, ammonia (NH 3) (0. For example, at about 850 ° C. The gas soft nitriding treatment is a method in which soft nitriding is performed with a gas, and there are a method in which ammonia gas and a carburizing gas are mixed and a method in which urea is decomposed. Soft nitriding using a mixture of ammonia gas and carburizing gas in a ratio of 1: 1 is the mainstream of gas soft nitriding.

  The cage 25 may be made of resin, that is, engineering plastic, instead of the iron plate. Here, the engineering plastic is an abbreviation for engineering plastics, which is excellent in heat resistance among synthetic resins and can be used in fields where strength is required. The engineering plastic includes general-purpose engineering plastic and super engineering plastic. The engineering plastic used for the cage 25 includes both. The following are typical examples. These are examples of engineering plastics, and engineering plastics are not limited to the following.

  General-purpose engineering plastics include 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) and the like. Super engineering plastics include polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polyarylate (PAR), polyamideimide (PAI), polyetherimide (PEI), and polyetheretherketone. (PEEK), liquid crystal polymer (LCP), thermoplastic polyimide (TPI), polybenzimidazole (PBI), polymethylbenten (TPX), poly 1,4-cyclohexanedimethylene terephthalate (PCT), polyamide 46 (PA46), There are polyamide 6T (PA6T), polyamide 9T (PA9T), polyamide 11,12 (PA11,12), fluororesin, polyphthalamide (PPA) and the like.

  Moreover, it is preferable to perform MoS2 process on the surface of a tapered roller. Here, the MoS2 treatment is a treatment in which the surface layer portion (base material surface layer portion) of the member to be coated is coated with MoS2 (molybdenum disulfide). For example, the base material surface layer portion is melted by heat to dissolve molybdenum disulfide. Incorporated into the base material and recrystallized. For this reason, this coating layer is strong against abrasion, hardly peeled off, and has an excellent effect of reducing sliding resistance.

  As the outer diameter of the retainer 25, the retainer 25 is moved from the state of FIG. 3A to the small axial side as shown by an arrow in FIG. ), The outer ring 23 and a part of the cage 25 come into contact with each other, and when this bearing A rotates and the cage 25 is centered as shown in FIG. The dimensions are set such that the cage 25 and the outer ring 23 are not in contact with each other with a predetermined clearance around the entire circumference. In other words, such a dimension means that the clearance between the retainer 25 and the outer ring 23 is such that the retainer 25 is disposed at the axial center and the retainer 25 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 25 is moved in the radial direction from the axial center.

  As a result, the outer ring 3 and the cage 5 are in contact at the initial stage of operation (FIG. 4B), but are not in contact during operation (FIG. 4C). 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” refers to the diameter of the column portion on the small diameter side of the cage 25 so that when the cage 25 incorporating the tapered roller 24 is assembled to the inner ring 22, the roller gets over the small collar 22 b of the inner ring 22. It means expanding greatly. “Caulking operation” refers to pushing the column portion of the small-diameter portion of the cage 25 greatly expanded as described above by pushing it with a mold from the outside.

  According to the tapered roller bearing of the present invention, when the cage 25 is in a neutral state, the cage 25 and the outer ring 23 are not in contact with each other and a clearance is generated, and the cage 25 is moved by the radial cage 25 from the neutral state. PCD can be raised by making a part of the outer ring contact with the outer ring, and the roller coefficient γ exceeds 0.94, so that contact between the outer ring 23 and the cage 25 is avoided in the neutral state. Above, the pillar width of the cage 25 can be increased. For this reason, it becomes possible to raise load capacity to the level of a full roller bearing (bearing which does not use a cage), without changing the bearing size. Thereby, the contact surface pressure can be reduced, the surface pressure in the stopped state is relaxed, and the fretting resistance is improved. In addition, the cage 25 and the tapered roller 24 can ensure a good contact state, and the roller can be smoothly rotated.

  Further, by setting the window angle θ of the cage 25 to 55 ° or more, it is possible to ensure a good contact state with the tapered roller 24, and by setting the window angle θ of the cage 25 to 80 ° or less, The pressing force in the radial direction is not increased, and smooth rotation can be obtained.

In particular, by applying MoS2 treatment to the surface of the tapered roller, the frictional resistance between the tapered roller and the rolling surfaces of the outer ring and the inner ring can be reduced. Therefore, it is possible to prevent more stable generation of Frette fin grayed, it is possible to bearing life improvement by load capacity enhancement, it is possible to achieve both anti Frette fin grayed improve the bearing life improvement .

  In addition, when the cage 25 is made of an iron plate, the rigidity of the cage 25 can be increased, and the tapered roller 24 can be stably held over a long period of time. Moreover, it is excellent in oil resistance and can prevent material deterioration due to immersion in oil. If the cage 25 is made of resin, the weight is light and the coefficient of friction is small, which is suitable for reducing torque loss and cage wear at the start of the bearing.

  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 are possible. For example, the number of tapered rollers 24 to be arranged is arbitrary. Further, as the retainer 25, a resin fiber or other engineering plastic blended with glass fiber or carbon fiber may be used for strength enhancement.

It is principal part sectional drawing of the transmission for motor vehicles which uses the tapered roller bearing which shows embodiment of this invention. It is a cross-sectional view of the tapered roller bearing. The tapered roller bearing is shown, (A) is a longitudinal sectional view before axial movement, and (B) is a longitudinal sectional view after axial movement. The tapered roller bearing is shown, (A) is a cross-sectional view showing the relationship between the cage and the outer ring when stationary, (B) is a cross-sectional view showing the relationship between the cage and the outer ring at the initial stage of rotation, B) is a cross-sectional view showing the relationship between the rotating cage and the outer ring. It is a principal part expanded sectional view of the said tapered roller bearing. It is principal part sectional drawing of the transmission for conventional vehicles.

Explanation of symbols

18 Pocket 22 Inner ring 23 Outer ring 24 Tapered roller 25 Cage

Claims (1)

The tapered rollers are held in a cage at equal intervals around the circumference, and are used for idler parts of automotive transmissions where the outer ring is idled with respect to the inner ring and the outer ring is switched to a shifted state in which the outer ring rotates synchronously with the inner ring. Tapered roller bearings that are subject to repeated loads from
In the neutral state of the cage, the cage and the outer ring are not in contact with each other, and a clearance is generated. By moving the cage in the radial direction from this neutral state, the cage can be brought into contact with the outer ring, raising the PCD, coefficient γ exceeds 0.94 rollers, and a window angle of a pocket of the cage with a less than 80 ° 55 ° or more, the surface pressure relieving structure in the stopped state, further, the MoS2 treatment on the surface of the tapered roller Tapered roller bearings characterized by the fact that they have been applied.

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