JP2008014473A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device having a longer life while preventing inconveniences including early separation of a surface layer even when using the wheel bearing device having reduced size and weight under high load conditions. <P>SOLUTION: The wheel bearing device comprises: an outer ring 10 having double row raceway surfaces formed in approximately conical shape on the inner diameter side; an inner ring 20 or a wheel mounting hub 50 having a raceway surface 21 formed in approximately conical shape on the outer diameter side in opposition to the raceway surfaces 11 of the outer ring 10; double row tapered rollers 30 arranged between the inside and outside raceway surfaces, and a pair of cages 40 for holding the tapered rollers 30 in rows at a predetermined peripheral space. In this case, cut crownings 11b, 11c, 21b, 21c are formed at the large diameter side end and the small diameter side end of the inside and outside raceway surfaces 11, 21, respectively, and the crowning amount of each of the large diameter side cut crownings 11b, 21b is larger than the crowning amount of each of the small diameter side cut crowning 11c, 21c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device having a double-row tapered roller bearing structure.

  As an automobile wheel bearing device, an outer ring having a double-row raceway surface formed in a substantially conical surface on the inner diameter side, and a pair of inner rings having a raceway surface formed in a substantially conical surface on the outer diameter side, Double-row tapered rollers provided with a double-row tapered roller disposed between the outer ring raceway surface and the inner ring raceway surface, and a pair of cages that hold the tapered rollers in each row at a predetermined interval in the circumferential direction. Some have a bearing as a base, and one of the outer ring and the inner ring is formed integrally with a wheel mounting hub, and the other is fixed to a vehicle body. The wheel bearing device includes an outer ring that is integrated with a hub, an outer ring rotating type that is mainly used for a driven wheel, and an inner ring that is integrated with a hub, and can be used as either a drive shaft or a driven wheel. Roughly divided into rotation types. As a wheel bearing device, there is a wheel bearing device in which one of a pair of inner rings is integrally formed with a hub and the other is fitted to the hub.

  In this type of wheel bearing device, when a high load such as a vehicle body load or a loaded load is applied during rotation, a slight angle difference occurs between the axial direction of the outer ring and the axial direction of the inner ring. Edge load (end concentrated load) is generated at the contact portion between the roller and the tapered roller raceway surface. When the edge load occurs, the outer ring raceway surface and the inner ring raceway surface are scratched in the circumferential direction, and in some cases, surface damage such as surface peeling may occur from this scratch.

  Conventionally, the crown load is formed on the outer ring raceway surface, the inner ring raceway surface, or the roller rolling surface, thereby preventing an increase in surface load at the edge load and the center portion of the raceway surface. Crowning means giving the outer ring raceway surface, the inner ring raceway surface or the roller rolling surface a slight bulge. Crowning includes full crowning formed over the entire region of the contact portion between the raceway surface and the rolling surface, and cut crowning formed at the end of the contact portion.

  In the case of double row tapered roller bearings, it is common to provide full crowning on the outer ring raceway surface and roller rolling surface, while providing cut crowning at both ends of the inner ring raceway surface (see, for example, Patent Document 1). Patent Document 1 discloses a structure in which a partial crowning (hereinafter referred to as partial crowning) is formed in the central portion of the inner ring raceway surface in the generatrix direction, and cut crowning is provided on both sides of the partial crowning. The cut crowning formed on the large diameter side of the inner ring raceway surface (hereinafter referred to as the large diameter side cut crowning) and the cut crowning formed on the small diameter side (hereinafter referred to as the small diameter side cut crowning) are generally asymmetric. Therefore, since the surface pressure on the large diameter side becomes higher than the small diameter side of the inner ring raceway surface, the crowning amount of the large diameter side cut crowning is set larger than that of the small diameter side cut crowning.

Japanese Patent Laid-Open No. 11-270553

  Conventionally, the inner ring tends to be more prone to problems such as surface peeling than the outer ring and tapered roller. Therefore, cut crowning is provided only at both ends of the inner ring raceway surface, and full crowning is provided on the outer ring raceway surface and roller rolling surface. Is provided.

  In recent years, with the reduction in weight of automobiles, there has been a demand for reduction in size and weight of wheel bearing devices. However, if the wheel bearing device is made small and light and cut crowning is provided only on the inner ring raceway as described above, an excessive edge load will occur on the outer ring raceway surface under high load conditions, and the outer ring raceway surface will be Problems such as surface layer peeling tend to occur. There is also a concern that the reaction of the edge load generated on the outer ring raceway surface significantly increases the surface pressure of the inner ring raceway surface, and the inner ring raceway surface is liable to cause defects such as surface peeling.

  The present invention was devised in view of such circumstances, and its object is to prevent the occurrence of excessive edge load on the outer ring raceway surface and the inner ring raceway surface, thereby extending the life of the wheel bearing device. There is.

  In order to solve the above problems, a wheel bearing device according to the present invention has an outer ring having a double row raceway surface formed in a substantially conical shape on the inner diameter side, and an outer diameter side so as to face the raceway surface of the outer ring. The inner ring or the wheel mounting hub having a raceway surface formed in a substantially conical surface, a double row tapered roller disposed between the inner and outer raceway surfaces, and a tapered roller in each row in a circumferential direction. In a wheel bearing device having a pair of cages held at intervals, a cut crowning is formed at each of a large-diameter side end and a small-diameter side end of each of the inner and outer raceway surfaces, and the large-diameter side cut crown The crowning amount is larger than the crowning amount of the small diameter side cut crowning (claim 1).

  The wheel bearing device described above is provided with cut crowning on the double row raceway surface of the outer ring and each raceway surface of the pair of inner rings, and the crowning amount of each large diameter side cut crowning is larger than the crowning amount of the small diameter side cut crowning. As a result, edge loads are less likely to occur on the outer ring raceway surface and the inner ring raceway surface. As a result, the surface pressure applied to the outer ring raceway surface and the inner ring raceway surface is reduced, so that the other surface pressure is significantly increased by the reaction of the surface pressure applied to either the outer ring raceway surface or the inner ring raceway surface. This can be suppressed.

  When the wheel bearing device of the present invention uses a pair of inner rings having a raceway surface formed on the outer diameter side so as to face the raceway surface of the outer ring, either one of the outer ring and the inner ring is used. A hub or a flange to which the hub is attached can be integrally formed, and the other can be fixed to the vehicle body.

  Further, the wheel bearing device of the present invention includes a wheel mounting hub having a raceway surface formed in a substantially conical shape on the outer diameter side so as to face one raceway surface of the outer ring, and the other raceway of the outer ring. An inner ring having a raceway surface formed in a substantially conical surface shape on the outer diameter side so as to face the surface and fitted to the hub can be provided.

  The wheel bearing device described above is also provided with cut crowning on the double row raceway surface, hub raceway surface and inner ring raceway surface of the outer ring, and the crowning amount of each large diameter side cut crowning is larger than the crowning amount of the small diameter side cut crowning. Therefore, an edge load is hardly generated on the outer ring raceway surface, the hub raceway surface, and the inner ring raceway surface. As a result, the surface pressure applied to the outer ring raceway surface, the hub raceway surface, and the inner ring raceway surface is reduced. Therefore, either the outer ring raceway surface or the hub raceway surface, or either the outer ring raceway surface or the inner ring raceway surface. It is possible to suppress the other surface pressure from significantly increasing due to the reaction of the surface pressure loaded on the surface.

  As described above, the present invention suppresses the occurrence of edge load on the outer ring raceway surface and the inner ring raceway surface, and the other surface pressure by the reaction of the surface pressure applied to either the outer ring raceway surface or the inner ring raceway surface. Therefore, it is difficult to cause problems such as surface peeling on the outer ring raceway surface and the inner ring raceway surface, and the life of the wheel bearing device can be extended.

  In addition, as described above, the present invention suppresses the occurrence of edge load on the outer ring raceway surface, the hub raceway surface, and the inner ring raceway surface, and either the outer ring raceway surface or the hub raceway surface, or the outer ring raceway surface or the inner ring raceway. Since the reaction pressure of the surface pressure applied to one of the raceway surfaces is suppressed from significantly increasing the other surface pressure, problems such as surface delamination occur on the outer ring raceway surface, hub raceway surface and inner ring raceway surface. This is less likely to occur and the life of the wheel bearing device can be extended.

  Hereinafter, an embodiment of a wheel bearing device according to the present invention will be described with reference to the drawings.

  FIG. 1 is an axial sectional view showing an embodiment of a wheel bearing device according to the present invention, and shows an example when the present invention is applied to an inner ring rotating drive shaft / driven wheel shared type wheel bearing device. ing. This wheel bearing device includes an outer ring 10, a pair of inner rings 20, 20, a plurality of tapered rollers 30, 30,..., A pair of cages 40, 40, and a hub 50 as main components.

  The outer ring 10 has double-row raceway surfaces 11 and 11 formed in a substantially conical surface on the inner diameter side. Seal members 12 and 12 are fitted and fixed to the outer sides of the raceway surfaces 11 and 11 in the axial direction. On the outer diameter side of the outer ring 10, a tab 13 extending outward in the radial direction is provided. The tab 13 is formed with a bolt hole 14 for bolting to the bearing case 1 of the vehicle body. The outer ring 10 is fitted in the bearing case 1 of the vehicle body, and the bolt hole 2 formed on the annular end surface of the bearing case 1 and the bolt hole 14 of the tab 13 are aligned and fixed by the bolt 3. Thereby, the play of the outer ring 10 with respect to the bearing case 1 in the circumferential direction is prevented.

  The pair of inner rings 20 has a raceway surface 21 formed in a substantially conical surface shape so as to face the raceway surface 11 of the outer ring 10 on each outer diameter side. On both sides of the raceway surfaces 21, 21 of the inner rings 20, 20, a large collar part 22 and a small collar part 23 are provided in order to hold the tapered rollers 30. A cover 24 is externally fitted on the outer diameter side of the large collar portion 22 so as to close both end openings between the outer ring 10 and the inner ring 20. The space between the outer ring 10 and the inner ring 20 is sealed by bringing the cover 24 into sliding contact with the seal members 12 and 12. This prevents the lubricant filled in the space between the outer ring 10 and the inner ring 20 from leaking to the outside, and prevents foreign matter such as muddy water and dust from entering the space between the outer ring 10 and the inner ring 20.

  The tapered rollers 30, 30,... Are arranged on double-row tracks formed between the outer ring raceway surfaces 11, 11 and the inner ring raceway surfaces 21, 21, and are contact-guided by the large collar portion 22 of the inner ring 20. .

  The pair of retainers 40, 40 are each formed in a conical cylinder shape, and are provided with a plurality of pockets 41 at a predetermined interval in the circumferential direction. One tapered roller 30 is accommodated in each of the pockets 41 of the cages 40, 40, and the tapered roller 30 is passed over the small flange portion 23 of the inner ring 20, and the tapered roller is interposed between the large flange portion 22 and the small flange portion 23. By fitting 30, the inner ring 20, the tapered roller 30 and the cage 40 are assembled.

  The hub 50 has a wheel mounting flange 51 for mounting a wheel (not shown) on the outer diameter side. Hub bolts 52 are fixed to the wheel mounting flanges 51 for fixing wheel disks at equal intervals in the circumferential direction. An inner ring fitting portion 53 that is press-fitted into the pair of inner rings 20 is formed on the inboard side of the wheel mounting flange 51 of the hub 50. On the other hand, on the inner diameter side of the hub 50, an axle fitting hole portion 54 that is fitted to the axle 4 so as to be able to transmit torque is provided. The axle fitting hole 54 is a spline hole that is spline fitted with the spline shaft 4 a of the axle 4. On the outer side in the axial direction of the axle fitting hole portion 54, an accommodation hole portion 55 for accommodating the nut 5 that is screwed into the male screw portion 4b provided at the tip of the axle shaft 4 is provided. The nut 5 is a member that locks the step portion 56 formed at the boundary between the axle fitting hole portion 54 and the accommodation hole portion 55 to prevent the hub 50 from coming off from the axle 4. In addition, the code | symbol 57 in a figure has shown the through-hole provided between the planting locations of the hub bolt 52. FIG. The through hole 57 is a hole for inserting a tool for bolting the outer ring 10 to the bearing case 1.

  FIG. 2 is an enlarged view of a portion A in FIG. 1 showing the tapered roller bearing structure on the inboard side, and shows the shape of each crowning exaggerated for easy understanding. Since the tapered roller bearing structure on the outboard side is substantially the same as the tapered roller bearing structure on the inboard side, illustration and description are omitted. In FIG. 2, illustration of the seal member 12, the cover 24, and the retainer 40 is omitted for convenience.

  As shown in FIG. 2, in the wheel bearing device described above, partial crowning 11 a, 21 a is formed at the center in the generatrix direction of each of the outer ring raceway surface 11 and the inner ring raceway surface 21. Large diameter cut crowns 11b and 21b and small diameter cut crowns 11c and 21c are formed on both sides of each partial crowning 11a and 21a. On the other hand, on the rolling surface 31 of the tapered roller 30, a full crowning 31a is formed in the entire region of the generatrix. On both sides of the roller rolling surface 31, R processed portions 32, 32 are formed. The R processing parts 32 and 32 are portions that do not contact the outer ring raceway surface 11 or the inner ring raceway surface 21 and are distinguished from the rolling surfaces 31 that can contact the outer ring raceway surface 11 or the inner ring raceway surface 21 due to elastic deformation or the like. Is done.

The individual crowning 11a, 21a formed on the outer ring raceway surface 11 and the inner ring raceway surface 21 and the full crowning 31a formed on the roller rolling surface 31 are line symmetric on the larger diameter side and the smaller diameter side from the apex, respectively. Have The symmetry axes L ₀ and L ₁ are axes orthogonal to the buses M ₀ and M _{1 of the} track surfaces 11 and 21 when no crowning is formed. In this embodiment, the vertices P ₀ and P ₁ of the partial crownings 11a and 21a are in contact with the vertices of the full crowning 31a. Therefore, the contacts (P ₀ and P ₁ ) of the outer ring 10 and the inner ring 20 with respect to the tapered rollers 30. , The axial direction positions of the tapered rollers 30 are the same, and the tapered rollers 30 are equidistant from the axis Lc of the tapered rollers 30. As a result, the tapered roller 30 rolls without causing a skew while maintaining a normal rotation axis (axis line Lc). In the figure, symbol C ₀ is the crowning amount of the partial crowning 11 a of the outer ring raceway surface 11, and symbol C ₁ is the crowning amount of the partial crowning 21 a of the inner ring raceway surface 21, and these values are appropriately set. Here, the crowning amount is the displacement in the direction perpendicular to the generatrix between the apex and the end of the crowning.

Over hand, the crowning amount of the large diameter side cut crowning 11b of the code _{C L0} is the outer ring raceway surface 11 in the figure, reference numeral _{W L0} is the width of the large-diameter side cuts crowning 11b of the outer ring raceway surface 11, reference numeral _{C S0} outer ring raceway surface crowning amount of the small diameter side cut crowning 11c 11, reference numeral _{W S0} is the width of the smaller-diameter side cut crowning 11c of the outer ring raceway surface 11. Similarly, the crowning amount of the large-diameter side cuts crowning 21b of the code _{C L1} is the inner ring raceway surface 21, reference numeral _{W L1} is the width of the large-diameter side cuts crowning 21b of the inner ring raceway surface 21, reference numeral _{C S1} is the small diameter inner ring raceway surface 21 The crowning amount of the side cut crowning 21 c, the symbol W _S1, is the width of the small diameter side cut crowning 21 c of the inner ring raceway surface 21. Here, the width of the crowning is the length of the crowning in the generatrix direction.

The outer diameter raceway surface 11 and the inner diameter raceway surface 21 have a larger diameter crown width 11b, 21b than the smaller diameter cut crownings 11c, 21c (C _L0 > C _S0 , W _L0 >). W _S0 , C _L1 > C _S1 , W _L1 > W _S1 ). By setting the large-diameter side cut crowns 11b and 21b in this way, the surface pressure generated on the large-diameter side of each of the outer ring raceway surface 11 and the inner ring raceway surface 21 can be reduced, and the outer ring raceway surface 11 and the inner ring raceway can be reduced. Edge loading of the surface 21 can be prevented. As a result, even if the wheel bearing device that is reduced in size and weight is used under high load conditions, defects such as surface peeling do not occur at an early stage, and the life of the wheel bearing device can be extended.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the pair of inner rings 20 are externally fitted to the hub 50. However, in the present invention, the inner ring 20 'on the outboard side is formed integrally with the hub 50 as shown in FIG. The present invention can also be applied to a wheel bearing device in which only the inner ring 20 on the side is externally fitted to the hub 50. The wheel bearing device of FIG. 3 is provided with a substantially conical raceway surface 21 ′ on the outer diameter side of the hub 50 so as to face the raceway surface 11 on the outboard side of the outer ring 10. The inner ring 20 on the inboard side having a substantially conical raceway surface 21 formed on the outer diameter side so as to face the raceway surface 11 is fitted to the hub 50. In FIG. 3, the seal member 12 fitted to the outboard side of the outer ring 10 is brought into contact with the hub 50, and a cover (24) is attached to the inner ring 20 ′ on the outboard side formed integrally with the hub 50. Absent.

  The wheel bearing device shown in FIGS. 1 and 3 is an inner ring rotating drive shaft / driven wheel shared type, so that the hub 50 is fitted with the axle 4 inside. In the case of the driven wheel type, it is not necessary to fit the axle 4 into the hub 50, so the axle fitting hole 54 need not be provided.

  Moreover, although the wheel bearing apparatus shown in FIG.1 and FIG.3 is an inner ring | wheel rotation type, this invention is applicable also to the type only for a driven wheel of outer ring | wheel rotation. For example, as shown in FIG. 4, the wheel bearing device dedicated to the driven wheel for rotating the outer ring is such that the outer ring 10 is bolted to the hub 50 and the inner ring 20 is externally fitted to the axle 4 ', as shown in FIG. The outer ring 10 is fitted into the hub 50 and the inner ring 20 is fitted onto the axle 4 '. 4 and 5, the axle 4 'may be a rotating shaft or a non-rotating shaft.

  The wheel bearing device shown in FIG. 4 is provided with a flange 13 'extending radially outward on the outer diameter side of the outer ring 1O. The flange 13 'is formed with a screw hole 14' for fixing the hub 50 with a bolt. In this embodiment, a brake disc 58 is interposed between the outer ring 10 and the hub 50. Further, circumferential grooves 25 and 25 are provided on the inner diameter side of the small flange portions 23 and 23 of the pair of inner rings 20 and 20, and are integrated by a connecting ring 26 that is crimped and fixed to the circumferential grooves 25 and 25. The inner ring 20, 20 is fitted with an axle 4 ′, and a nut 5 ′ engaged with a male screw part 4 b ′ provided at the tip of the axle 4 ′ is engaged with the end surface of the inner ring 20 on the outboard side. The inner ring 20, 20 is prevented from coming off from the axle 4 '. A bolt hole 60 for inserting a fixing bolt 59 with respect to the outer ring 10 is provided on the end face on the inboard side of the hub 50.

  The wheel bearing device shown in FIG. 5 has a tapered roller bearing that does not include the tab 13 or the flange 13 ′ and is fitted into the hub 50. A circumferential groove 61 is formed on the inner diameter side of the hub 50, and a retaining ring 62 attached to the circumferential groove 61 is engaged with an end surface of the inner ring 20 on the inboard side, so that the hub 50 comes off from the tapered roller bearing. Is preventing.

  4 and 5, the outer ring 10 formed separately from the hub 50 is shown integrated with the hub 50 by bolting or fitting, but the outer ring 10 is integrated with the hub 50. It is also possible to mold it.

  The result of having measured the surface pressure in the raceway surface of the inner ring | wheel and outer ring | wheel of the wheel bearing apparatus of this invention is shown to FIG. 6A. The wheel bearing device used for the measurement is such that cut crowning is formed on the raceway surfaces of the inner ring and the outer ring, and full crowning is formed on the roller rolling surfaces. As can be seen from the figure, although the surface pressure slightly increased in the central region of the outer ring raceway surface, it was confirmed that the edge load did not rise at all on the large diameter side and the small diameter side. On the other hand, in the conventional wheel bearing device, a full crowning is formed on the outer ring raceway surface instead of a cut crowning, and a cut crowning is formed only on the inner ring raceway surface (the roller rolling surface is full crowning). As shown in FIG. 6B, it can be seen that extreme edge loads rise on the large diameter side and the small diameter side, and in particular, the edge load on the large diameter side exceeds the allowable surface pressure.

It is an axial direction sectional view showing one embodiment of a wheel bearing device concerning the present invention. It is a principal part enlarged view of FIG. It is an axial direction sectional view showing other embodiments of the wheel bearing device concerning the present invention. It is an axial direction sectional view showing one embodiment of a wheel bearing device concerning the present invention. It is an axial direction sectional view showing one embodiment of a wheel bearing device concerning the present invention. It is a figure which shows the result of having measured the surface pressure in the raceway surface of the inner ring | wheel and outer ring | wheel of the wheel bearing apparatus which concerns on this invention. It is a figure which shows the result of having measured the surface pressure in the raceway surface of the inner ring | wheel and outer ring | wheel of the conventional wheel bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing case 2 Bolt hole 3 Bolt 4 Axle 4a Spline shaft part 4b Male thread part 5 Nut 1O Outer ring 11 Outer ring raceway surface 11a Partial crowning 11b Large diameter side cut crown 11c Small diameter side cut crown 12 Seal member 13 Tab 13 'Flange 14 Bolt Hole 14 'Screw hole 20 Inner ring 21 Raceway surface 21a Partial crowning 21b Large diameter cut crown 21c Small diameter cut crown 22 Large collar 23 Small collar 24 Cover 25 Circumferential groove 26 Connecting ring 31 Rolling surface 31a Full crowning 32 R processing Part 40 Cage 41 Pocket 50 Hub 51 Wheel mounting flange 52 Hub bolt 53 Inner ring fitting part 54 Axle fitting hole part 55 Housing hole part 56 Step part 57 Through hole 58 Brake disk 59 Fixing bolt 60 Bolt hole 61 Circumferential groove 62 Stop ring

Claims (3)

  An outer ring having a double row raceway surface formed in a substantially conical surface on the inner diameter side, and an inner ring or wheel mounting having a raceway surface formed in a substantially conical surface on the outer diameter side so as to face the raceway surface of the outer ring Wheel bearing device comprising: a hub for use, a double row tapered roller disposed between the inner and outer ring raceway surfaces, and a pair of cages that hold the tapered roller in each row at a predetermined interval in the circumferential direction In addition, a cut crowning is formed at each of the large-diameter side end portion and the small-diameter side end portion of the inner and outer raceway surfaces, and the crowning amount of the large-diameter side cut crowning is made larger than the crowning amount of the small-diameter side cut crowning. Wheel bearing device.   It has a pair of inner rings having a raceway surface formed in a substantially conical surface on the outer diameter side so as to face the raceway surface of the outer ring, and either the outer ring or the inner ring is integrated with a flange to which the hub or the hub is attached. 2. The wheel bearing device according to claim 1, wherein the other is fixed to the vehicle body.   A wheel mounting hub having a raceway surface formed in a substantially conical surface on the outer diameter side so as to face one of the raceways of the outer ring, and an outer diameter side so as to face the other raceway surface of the outer ring. 2. The wheel bearing device according to claim 1, further comprising an inner ring having a raceway surface formed in a conical surface shape and fitted to the hub.

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