JP2018197598A - Hub unit for drive wheel - Google Patents

Abstract

To achieve the structure capable of preventing preload changes of a rolling element and the reduction in the connection strength of components constituting the inner member preventing occurrence of fretting abrasion at the engagement part between the face splines while being possible to downsizing and weight saving.SOLUTION: A hub body 30 includes: an inner ring raceway 9c on the axial outside; a rotary flange 10a; a first center hole 32; and a first face spline 16a. A joint outer ring 3a includes: a shank 19a; an inner ring raceway 9d on the axial inside; a second center hole 39; and a second face spline 21a. The hub body 30 and the joint outer ring 3a are fitted with the axial direction inner end of the hub body 30 and the axial direction outer end of the joint outer ring 3a, respectively; and the first face spline 16a and the second face spline 21a are engaged and fixed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drive wheel hub unit for rotatably supporting a drive wheel of an automobile with respect to a suspension device and for driving the drive wheel to rotate.

  A driving wheel and a braking rotator of an automobile are rotatably supported with respect to a suspension device by a driving wheel hub unit, and can transmit torque from a driving shaft. FIG. 7 shows the structure of the drive wheel hub unit 1 described in Japanese Patent Application Laid-Open No. 2014-92186. The drive wheel hub unit 1 shown in FIG. 7 is configured by combining a hub unit bearing 2 and a joint outer ring 3.

  The hub unit bearing 2 includes an outer ring 4, a hub 5, and a plurality of rolling elements 6. The outer ring 4 includes double-row outer ring raceways 7a and 7b and a stationary flange 8 for supporting and fixing the outer ring 4 to a knuckle of a suspension device. The double row outer ring raceways 7 a and 7 b are provided on the inner peripheral surface of the outer ring 4. The stationary flange 8 is provided at an axially intermediate portion of the outer ring 4 so as to protrude radially outward.

  The hub 5 is disposed coaxially with the outer ring 4 on the inner diameter side of the outer ring 4, and includes a double row of inner ring raceways 9a and 9b, and a rotating flange 10 for supporting a wheel and a braking rotator (not shown). Have The double row inner ring raceways 9 a and 9 b are provided on the outer peripheral surface of the hub 5 at a portion facing the double row outer ring raceways 7 a and 7 b. The rotating flange 10 is provided on the outer side in the axial direction of the hub 5 existing outside in the axial direction from the outer end surface in the axial direction of the outer ring 4 with respect to the axial direction so as to protrude radially outward.

  A plurality of rolling elements 6 are disposed between the outer ring raceways 7a and 7b in the double row and the inner ring raceways 9a and 9b in the double row so as to be freely rollable in each row. With such a configuration, the hub 5 is rotatably supported on the inner diameter side of the outer ring 4.

  In the illustrated example, the hub 5 is configured by combining a hub body 11 and an inner ring 12. The hub body 11 has an inner ring raceway 9a on the outer side in the axial direction of the double row inner ring raceways 9a and 9b on the outer peripheral surface in the axial direction, and a rotating flange 10 on the outer side in the axial direction. The hub body 11 is provided on the inner side in the axial direction and has a small diameter step portion 13 having an outer diameter smaller than the outer diameter of the portion adjacent to the outer side in the axial direction, and a central hole penetrating the central portion in the axial direction. 14. Note that “outside” in the axial direction refers to the left side of FIGS. 1 to 7, which is the outside of the vehicle when the drive wheel hub unit 1 is assembled to an automobile. On the other hand, the right side of FIGS. 1 to 7, which is the center side of the vehicle with the drive wheel hub unit 1 assembled to an automobile, is referred to as “inside” in the axial direction.

  The inner ring 12 has an inner ring raceway 9b on the outer peripheral surface on the inner side in the axial direction of the double row inner ring raceways 9a and 9b. Such an inner ring 12 is externally fitted to the small-diameter step portion 13, and a portion of the small-diameter step portion 13 that protrudes inward in the axial direction from the inner end surface in the axial direction of the inner ring 12 is plastically deformed outward in the radial direction. The inner end face in the axial direction is pressed down by the caulking portion 15 formed by doing so. As a result, an appropriate preload is applied to the rolling elements 6, and separation of the inner ring 12 from the hub body 11 is prevented. A first face spline 16 that is an uneven portion in the circumferential direction is provided on the inner end surface in the axial direction of the caulking portion 15 over the entire circumference.

  The joint outer ring 3 includes a cup-shaped mouth portion 17, an end wall portion 18 that is a bottom portion of the mouth portion 17, and a cylindrical shaft portion 19 that extends axially outward from the center portion of the end wall portion 18. Prepare. In the illustrated example, the central hole of the shaft portion 19 is a screw hole 20. A second face spline 21 that is a concavo-convex portion in the circumferential direction is provided over the entire circumference on the radially outer portion of the axially outer end surface of the end wall portion 18. The number of teeth of the second face spline 21 is the same as the number of teeth of the first face spline 16.

  The hub 5 and the joint outer ring 3 are coupled and fixed so as to be able to transmit a rotational force in a state in which the center axes thereof coincide with each other and the first face spline 16 and the second face spline 21 are engaged with each other. Has been. Specifically, a bolt 22 inserted through the center hole 14 from the outside in the axial direction is screwed into the screw hole 20 and further tightened.

  A joint inner ring 23 is supported via a plurality of balls 24 on the inner diameter side of the mouse portion 17 of the joint outer ring 3. In a state where the drive wheel hub unit 1 is assembled to an automobile, a drive shaft (not shown) is connected to the inner diameter side of the joint inner ring 23 so as to transmit torque by spline engagement or the like. When the joint inner ring 23 is rotationally driven by the drive shaft during traveling of the automobile, this rotation is transmitted to the joint outer ring 3 via the ball 24. The rotation of the joint outer ring 3 is transmitted to the hub 5 from the meshing portion of the first face spline 16 and the second face spline 21, and with the rotation of the hub 5, the wheel supported by the rotating flange 10 and the brake The rotating body is driven to rotate.

  In the structure described in Japanese Patent Application Laid-Open No. 2014-92186, the hub unit bearing 2 and the joint outer ring 3 can be easily separated by simply removing the bolts 22, so that maintainability can be improved.

JP 2014-92186 A

  The structure shown in FIG. 7 has room for improvement from the following aspects. That is, the drive wheel hub unit 1 is configured by combining the hub unit bearing 2 and the joint outer ring 3. For this reason, the axial dimension of the drive wheel hub unit 1 increases, which is disadvantageous in terms of reducing the size and weight of the drive wheel hub unit 1. Since the drive wheel hub unit 1 is installed under the spring on the road surface side of the spring constituting the suspension device, when the weight of the drive wheel hub unit 1 increases, the unsprung load increases, and the ride comfort and running are increased. Stability may deteriorate. Further, in the illustrated example, the hub 5 constituting the hub unit bearing 2 is configured by combining a hub body 11 and an inner ring 12. Therefore, the number of parts is large, and assembly work and parts management are troublesome.

  The first face spline 16 has an L-shaped cross section and is provided on the inner end surface in the axial direction of the caulking portion 15 that is thin in both the axial direction and the radial direction. Therefore, when a large torque is input from the engine and a large force is applied from the second face spline 21 to the first face spline 16, the cylindrical portion extending in the axial direction in the caulking portion 15 is elastically deformed in the twisting direction. there's a possibility that. When the cylindrical portion of the caulking portion 15 is elastically deformed, the radial dimension of the cylindrical portion is slightly reduced, so that the force pressing the inner end surface in the axial direction of the inner ring 12 is changed, and the preload applied to the rolling element 6 is changed. May also change.

  Further, when the vehicle turns, a large moment load based on the road surface reaction force is applied to the rotating flange 10, so that the hub unit bearing 2 is bent or a large torque is input from the engine. If twisting occurs between the first face spline 16 and the second face spline 21, the bolt 22 may loosen, and fretting wear may occur at the meshing portion between the first face spline 16 and the second face spline 21.

  In view of the circumstances as described above, the present invention can be reduced in size and weight, and the preload change of the rolling elements, the reduction in the coupling strength of the members constituting the inner member, and the meshing portion between the face splines can be achieved. An object of the present invention is to realize a drive wheel hub unit structure capable of preventing occurrence of fretting wear.

The drive wheel hub unit of the present invention includes an outer member, an inner member, and a rolling element.
The outer member has a double row outer ring raceway on an inner peripheral surface.
The inner member has double-row inner ring raceways on the outer peripheral surface.
A plurality of rolling elements are arranged between the outer row raceway in the double row and the inner raceway in the double row so as to roll freely for each row.
The inner member includes a hub body, a joint outer ring, and a coupling member.
The hub body has an inner ring raceway on the outer side in the axial direction of the double row inner ring raceways on the outer circumferential surface of the axially intermediate portion, and has a rotating flange on the outer side in the axial direction and penetrates in the axial direction at the center. The first center hole is provided with a first face spline on a side surface present on the inner side in the axial direction from the inner ring raceway on the outer side in the axial direction.
The joint outer ring includes a shaft portion having an inner ring raceway on the inner side in the axial direction of the double row inner ring raceways on an outer circumferential surface in the axial direction, and a second center hole penetrating the central portion of the shaft portion in the axial direction. And a second face spline on a side surface that is located on the outer side in the axial direction than the inner ring raceway on the inner side in the axial direction.
The coupling member is inserted or screwed into the first center hole and the second center hole to couple and fix the hub body and the joint outer ring.
The first face spline and the second face spline are engaged with each other, and the axially inner end of the hub body and the axially outer end of the joint outer ring are fitted (in the radial direction). Is superimposed). Specifically, the axial outer end of the joint outer ring is fitted into the axial inner end of the hub body, or the axially inner end of the hub main body is inserted into the axial outer end of the joint outer ring. The end is fitted inside. The radial clearance between the inner peripheral surface or outer peripheral surface of the axially inner end portion of the hub body and the outer peripheral surface or inner peripheral surface of the axial outer end portion of the joint outer ring facing each other is the center axis of the hub main body. It is preferable that it is 5 micrometers or less in the state which made the center axis | shaft of a joint outer ring correspond.

  According to the drive wheel hub unit of the present invention, it is possible to reduce the size and weight of the drive wheel, to change the preload of the rolling element, to reduce the coupling strength of the members constituting the inner member, and to fretting at the meshing portion between the face splines. The occurrence of wear can be prevented.

FIG. 1 is a sectional view showing a drive wheel hub unit according to a first example of an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a method for grinding the drive wheel hub unit of the first example of the embodiment of the present invention. FIG. 3 is a cross-sectional view showing another example of a method of grinding the drive wheel hub unit of the first example of the embodiment of the present invention. FIG. 4 is a partially enlarged view of the meshing portion between the first face spline and the second face spline as viewed from the outside in the radial direction. FIG. 5 is a cross-sectional view showing another example of a method for temporarily fixing the hub body and the joint outer ring. FIG. 6 is a sectional view showing a drive wheel hub unit according to a second example of the embodiment of the present invention. FIG. 7 is a cross-sectional view showing an example of a conventional structure of a drive wheel hub unit.

[First example of embodiment]
FIG. 1 shows a first example of an embodiment of the present invention. The hub unit 1a for driving wheels of this example includes an outer ring 4 that is an outer member, an inner member 25, and a plurality of rolling elements 6. The outer ring 4 is made of a hard metal such as medium carbon steel, and includes double-row outer ring raceways 7a and 7b, and a stationary flange 8 for supporting and fixing the outer ring 4 to a suspension device. The double row outer ring raceways 7 a and 7 b are provided on the inner peripheral surface of the outer ring 4. The stationary flange 8 is provided at an axially intermediate portion of the outer ring 4 so as to protrude radially outward. Support holes 26 are respectively provided at a plurality of locations in the circumferential direction of the radial intermediate portion of the stationary flange 8. The outer ring 4 is supported and fixed to the knuckle 27 by screwing bolts (not shown) inserted through the through holes 28 of the knuckle 27 constituting the suspension device into the respective support holes 26.

  The inner member 25 is disposed coaxially with the outer ring 4 on the inner diameter side of the outer ring 4, and includes double-row inner ring raceways 9c and 9d and a rotating flange 10a. The double-row inner ring raceways 9c and 9d are provided in a portion of the inner member 25 facing the double-row outer ring raceways 7a and 7b. The rotary flange 10a is provided on the outer side in the axial direction of the inner member 25 that exists on the outer side in the axial direction with respect to the outer end surface in the axial direction of the outer ring 4 with respect to the axial direction. Attachment holes 29 are respectively provided at a plurality of locations in the circumferential direction on the radially outer side of the rotary flange 10a. The wheel and the brake rotating body are supported on the rotating flange 10a by a connecting member such as a stud press-fitted into each of the mounting holes 29 or a screwed hub bolt.

  In this example, the inner member 25 is configured by coupling and fixing a hub body 30 made of a hard metal such as medium carbon steel or bearing steel and a joint outer ring 3a with a bolt 31 that is a coupling member. .

  The hub main body 30 has the inner ring raceway 9c on the outer side in the axial direction of the double row inner ring raceways 9c and 9d on the outer peripheral surface in the axial direction, and the rotation flange 10a in the intermediate portion in the axial direction. The hub body 30 also has a first center hole 32 that passes through the center of the hub body 30 in the axial direction. The axially inner portion of the first central hole 32 is a cylindrical surface-shaped fitting hole 33 having an inner diameter smaller than the inner diameter of the axially outer portion of the first central hole 32.

  Further, the hub body 30 has a first face spline 16a formed on the inner end surface in the axial direction by arranging convex portions (teeth) protruding inward in the axial direction at equal intervals in the circumferential direction. The first face spline 16 a is provided over the entire radial width of the inner end surface in the axial direction of the hub body 30. That is, the teeth constituting the first face spline 16a are provided so as to cross the inner end face in the axial direction of the hub body 30 and are arranged radially. In other words, the tooth grooves constituting the first spline 16 a are open to the outer peripheral edge and the inner peripheral edge of the axially inner end face of the hub body 30. In this example, the tooth tip surface and the tooth bottom surface of the first face spline 16 a are flat surfaces orthogonal to the central axis of the hub body 30. Such a first face spline 16 a is formed by cold forging the hard metal material constituting the hub body 30. Specifically, the shape of the entire hub body 30 can be formed by cold forging, or the shape of the portion of the hub body 30 excluding the first face spline 16a and its peripheral portion is hot forged. Then, the first face spline 16a and its peripheral part can be formed by cold forging.

  The joint outer ring 3 a includes a cylindrical wall portion 34 and a cup-shaped mouth portion 17 a having a bottom portion 35 bent radially inward from an axially outer end portion of the wall portion 34, and an axial direction from the center portion of the bottom portion 35. It comprises a stepped cylindrical shaft portion 19a extending outward.

  The shaft portion 19 a is a step portion that connects the large-diameter cylindrical portion 36 in the axially inner portion, the small-diameter cylindrical portion 37 in the axially outer portion, and the outer peripheral surface of the large-diameter cylindrical portion 36 and the outer peripheral surface of the small-diameter cylindrical portion 37. 38, and has a second center hole 39 penetrating the center portion of the shaft portion 19a in the axial direction. The large-diameter cylindrical portion 36 has an inner ring raceway 9d on the inner side in the axial direction of the double row inner ring raceways 9c and 9d on the outer peripheral surface of the intermediate portion in the axial direction. The small diameter cylindrical portion 37 has an outer diameter that is slightly smaller than the inner diameter of the fitting hole 33 of the first center hole 32. An axially inner portion of the second center hole 39 is a screw hole 40. An escape recess 41 having an arcuate cross section is provided over the entire circumference at a portion extending from the axial inner end of the small diameter cylindrical portion 37 to the radial inner end of the stepped portion 38.

  The step portion 38 has the same outer diameter as the outer diameter of the inner end portion in the axial direction of the hub body 30. Such a stepped portion 38 is provided with a second face spline 21a in which convex portions (teeth) protruding outward in the axial direction are arranged at equal intervals in the circumferential direction. The second face spline 21a is provided on the radially outer portion of the step portion 38 excluding the radially inner end where the relief recess 41 is provided. That is, the teeth constituting the second face spline 21a are radially arranged on the radially outer side of the step portion 38, and the tooth grooves constituting the second face spline 21a are formed on the outer peripheral edge of the step portion 38 and The relief recess 41 is open. Therefore, the radial width dimension of the second face spline 21a is smaller than the radial width dimension of the first face spline 16a. It should be noted that the tooth tip surface and the tooth bottom surface of the second face spline 21a are each a plane orthogonal to the central axis of the joint outer ring 3a.

  The second face spline 21a is formed by cold forging the hard metal material constituting the joint outer ring 3a. Specifically, the shape of the entire joint outer ring 3a can be formed by cold forging, or the shape of the joint outer ring 3a excluding the second face spline 21a and its peripheral part is hot forged. Then, the second face spline 21a and its peripheral part can be formed by cold forging.

  The hub main body 30 and the joint outer ring 3a fit the small-diameter cylindrical portion 37 into the fitting hole 33 without rattling in the radial direction, and mesh the first face spline 16a and the second face spline 21a. In this state, the connection is fixed. Specifically, the bolt 31 inserted through the axially outer portions of the first center hole 32 and the second center hole 39 is screwed into the screw hole 40 and further tightened, whereby the hub main body 30 and the joint outer ring 3a. And are fixed. In other words, the hub body 30 is sandwiched in the axial direction between the head portion 42 of the bolt 31 and the joint outer ring 3a. In this way, the inner member 25 is configured. The radial clearance between the outer peripheral surface of the small diameter cylindrical portion 37 and the inner peripheral surface of the fitting hole 33 is 5 μm in a state where the central axis of the hub main body 30 and the central axis of the joint outer ring 3a are aligned. It is as follows. In other words, the difference between the outer diameter of the small diameter cylindrical portion 37 and the inner diameter of the fitting hole 33 is 10 μm or less.

  A plurality of rolling elements 6 are rotatably arranged between the outer ring raceways 7a and 7b in the double row and the inner ring raceways 9c and 9d in the double row for each row. The rolling elements 6 in each row are held by holders 43a and 43b. In this example, balls are used as the rolling elements 6, but tapered rollers can also be used.

  In addition, both axial ends of the cylindrical inner space 44 existing between the inner peripheral surface of the outer ring 4 and the outer peripheral surface of the inner member 25 are closed by seal rings 45a and 45b, respectively.

  The joint inner ring 23 is supported via a plurality of balls 24 (see FIG. 7) on the inner diameter side of the wall portion 34 of the mouse portion 17a constituting the joint outer ring 3a. In a state where the drive wheel hub unit 1a is assembled to an automobile, a drive shaft connected to a power source such as an engine is engaged with the inner diameter side of the joint inner ring 23 so as to transmit torque. When the joint inner ring 23 is rotationally driven by the drive shaft during traveling of the automobile, this rotation is transmitted to the joint outer ring 3 a via the ball 24. The rotation of the joint outer ring 3a is transmitted to the hub main body 30 from the meshing portion of the first face spline 16a and the second face spline 21a. The braking rotator is driven to rotate.

  In the drive wheel hub unit 1a of the present example, the maintenance can be improved because the hub body 30 and the joint outer ring 3a can be separated by removing the bolt 31 during maintenance.

  According to the drive wheel hub unit 1a of this example, it is possible to reduce the size and weight, change the preload of the rolling element 6, decrease the coupling strength between the hub body 30 and the joint outer ring 3a, and the first face spline. It is possible to prevent the occurrence of fretting wear at the meshing portion between 16a and the second face spline 21a.

  That is, in this example, the inner member 25 is configured by combining the hub body 30 having the outer ring surface with the inner ring raceway 9c on the outer circumferential surface and the joint outer ring 3a having the inner ring raceway 9d on the outer circumferential surface with the axial inner side. Has been. Therefore, the drive wheel hub unit 1a of this example is compared with the structure in which the drive wheel hub unit 1 is configured by combining the hub unit bearing 2 and the joint outer ring 3 as in the conventional structure of FIG. Thus, the axial dimension can be easily shortened, and the size and weight can be easily reduced. Further, the drive wheel hub unit 1a of the present example does not include the inner ring 12 having the inner ring raceway 9b on the outer peripheral surface as in the conventional structure of FIG. Work and parts management can be facilitated.

  In this example, the hub body 30 does not have the caulking portion 15 as in the conventional structure of FIG. For this reason, the thickness in the axial direction of the portion of the hub body 30 that is located on the axially outer side of the first face spline 16a is sufficiently larger than that of the conventional structure in FIG. Further, in the present example, the second face spline 21a is provided on the stepped portion 38 that faces outward in the axial direction and exists outside the inner ring raceway 9d on the inner side in the axial direction. For this reason, the thickness in the axial direction of the portion of the joint outer ring 3a that is axially inward of the second face spline 21a is the axially outer surface of the end wall 18 as in the conventional structure of FIG. Compared with the structure having the second face spline 21, the size is sufficiently large. Therefore, even when a large torque is input from the engine and a large force is applied from the second face spline 21a to the first face spline 16a, the hub body 30 is more outward in the axial direction than the first face spline 16a. It is possible to sufficiently suppress the existing portion and the portion of the joint outer ring 3a existing on the inner side in the axial direction from the second face spline 21a from being elastically deformed in the torsional direction. This prevents the preload applied to the rolling element 6 from changing.

  Furthermore, in this example, the small diameter cylindrical portion 37 of the shaft portion 19a constituting the joint outer ring 3a is fitted in the fitting hole 33 of the center hole 32 constituting the hub body 30 without looseness in the radial direction, And the axial direction of the part which exists in the axial direction outside of the first face spline 16a in the hub main body 30, and the part which exists in the axial direction inside of the second face spline 21a in the joint outer ring 3a. The wall thickness regarding is sufficiently large. For this reason, even when a large moment load based on the road surface reaction force is applied to the rotating flange 10a when the vehicle is turning, the bending of the inner member 25 can be eliminated or reduced. Further, even when a large torque is input from the engine, the torsion that occurs between the hub main body 30 and the joint outer ring 3a can be suppressed to a low level. As a result, the bolt 31 for connecting and fixing the hub main body 30 and the joint outer ring 3a is loosened, or fretting wear occurs at the meshing portion between the first face spline 16a and the second face spline 21a. Can be prevented.

  By the way, in this example, the meshing part of the 1st face spline 16a and the 2nd face spline 21a exists in the part between inner ring track 9c and 9d of double rows about an axial direction. Therefore, if the shape accuracy of the hub body 30 and the shape accuracy of the joint outer ring 3a are managed independently, the preload management of the rolling element 6 becomes troublesome. Therefore, a method for facilitating the preload management of the rolling element 6 will be described below.

In the method shown in FIG. 2, first, the small-diameter cylindrical portion 37 is fitted into the fitting hole 33 without rattling in the radial direction, and the first face spline 16a and the second face spline 21a are engaged with each other. . In this state, the bolt 31a inserted in the axially outer side portion of the first center hole 32 and the second center hole 39 is screwed into the screw hole 40 and further tightened, whereby the hub body 30 and the joint outer ring 3a Temporarily fix. Then, the hub main body 30 includes an outer circumferential surface in the axial direction inside the hub main body 30 including the inner ring raceway 9c on the outer side in the axial direction and an outer peripheral surface in the axial direction outer side of the outer ring 3a including the inner ring raceway 9d in the axial direction. and subjected to grinding by form-grinding wheel 46 having a central axis O and parallel to the rotation axis C ₁ of the outer race 3a. That is, in the state where the machining surface, which is the outer peripheral surface of the general-purpose grindstone 46, is abutted against the outer peripheral surface in the axially inner portion of the hub body 30 and the outer peripheral surface in the axially outer portion of the joint outer ring 3a, The main body 30 and the joint outer ring 3a are relatively rotated. Specifically, the general-purpose grindstone 46, the hub main body 30, and the joint outer ring 3a are rotated in directions opposite to each other when viewed from the axial direction.

  In such a method using the general-purpose grindstone 46, it is necessary to grind the axial side surface having an inclination angle of 45 degrees or more with respect to the central axis, such as the axial inner side surface of the rotary flange 10a and the axial outer side surface of the bottom 35. This is applicable to a structure in which the seal lips constituting the seal rings 45a and 45b do not slide on the side surfaces in the axial direction.

Next, a case where it is necessary to grind the axial side surface, such as a structure in which the seal rings 45a and 45b have side lips, will be described with reference to FIG. In this case, first, the small-diameter cylindrical portion 37 is fitted into the fitting hole 33 without rattling in the radial direction, and the first face spline 16a and the second face spline 21a are engaged with each other. In this state, the hub body 30 and the joint outer ring 3a are temporarily fixed. In the example of FIG. 3, a nut 47 is screwed into a tip portion of a bolt 31 b inserted through the second center hole 39 and the first center hole 32 from the inner side in the axial direction, and further tightened. The outer ring 3a is temporarily fixed. That is, the hub body 30 and the joint outer ring 3a are sandwiched in the axial direction between the head portion 42a of the bolt 31b and the nut 47. By grinding wheel 48 having an axis of rotation C ₂ which is inclined with respect to the center axis O of the hub body 30 and the joint outer ring 3a, the radial direction of the rotating flange 10a in the axial direction outside of the inner ring raceway 9c of the outer peripheral surface of the hub body 30 Grinding is performed on the portion of the inner end portion extending toward the inner surface in the axial direction and the portion of the joint outer ring 3 a extending from the inner ring raceway 9 d on the inner side in the axial direction to the outer surface in the axial direction of the bottom portion 35.

The grindstone 48 having an axis of rotation C ₂ which is inclined with respect to the center axis O, when subjected to grinding the outer peripheral surface of the outer peripheral surface and outer race 3a of the hub body 30, for example, the outer peripheral surface of the hub body 30 and the joint outer ring After grinding the outer peripheral surface of any one of the outer peripheral surfaces of 3a, the other outer peripheral surface can be ground. Alternatively, the grindstone 48 that grinds the outer peripheral surface of the hub main body 30 and the grindstone 48 that grinds the outer peripheral surface of the joint outer ring 3a are arranged in different phases in the circumferential direction, and the outer peripheral surface of the hub main body 30 and the joint outer ring 3a. It is also possible to grind the outer peripheral surfaces of the two at the same time.

  Even when the outer peripheral surface of the hub main body 30 and the outer peripheral surface of the joint outer ring 3a are ground by any one of the method illustrated in FIG. 2 and the method illustrated in FIG. 3, the bolt 31a, 31b is removed, the hub body 30 and the joint outer ring 3a are separated, and washed as necessary. Thereafter, the outer ring 4 and the rolling element 6 are arranged around the inner member 25 composed of the hub body 30 and the joint outer ring 3a in accordance with an appropriate assembly sequence. Then, the hub body 30 and the joint outer ring 3a are coupled and fixed by bolts 31 to constitute the drive wheel hub unit 1a.

  As described above, the hub main body 30 and the joint outer ring 3a are separated after the outer peripheral surface is ground in a temporarily fixed state, and the outer ring 4 and the rolling element 6 are arranged around, and then combined again. . Therefore, it is important to make the combined state of the hub main body 30 and the joint outer ring 3a the same at the time of temporary fixing and at the time of assembling the drive wheel hub unit 1a.

  For this purpose, it is necessary to match the meshing phase of the second face spline 21a with the first face spline 16a at the time of temporary fixing and when the drive wheel hub unit 1a is assembled. Therefore, for example, marks can be provided on the outer peripheral surface of the hub body 30 and the outer peripheral surface of the joint outer ring 3a. Alternatively, for example, as shown in FIG. 4, the circumferential length of any one of the plurality of teeth constituting the second face spline 21a is made longer than the other teeth, and The second face spline 21a becomes the first face by making the circumferential interval at any one of the portions between the plurality of teeth constituting one face spline 16a longer than the other portions. The spline 16a can also be configured to mesh only at a specific phase. The radial clearance between the outer peripheral surface of the small diameter cylindrical portion 37 and the inner peripheral surface of the fitting hole 33 is 5 μm in a state where the central axis of the hub main body 30 and the central axis of the joint outer ring 3a are aligned. It is as follows. For this reason, the hub body 30 and the joint outer ring 3a can be rotated relative to each other while ensuring the coaxiality. Therefore, the meshing phase of the second face spline 21a with respect to the first face spline 16a can be easily adjusted.

  Further, the tightening force of the bolts 31a and 31b at the time of temporary fixing is measured by an axial force sensor or the like and managed to an appropriate size. Specifically, the axial force of the bolts 31a and 31b at the time of temporary fixing is set to the same magnitude as the axial force of the bolt 31 constituting the drive wheel hub unit 1a.

  The threaded hole 40 of the joint outer ring 3a is made stronger than the male threaded portion of the bolts 31, 31a, 31b by processing with a rolling tap. Moreover, the bolts 31a and 31b used at the time of temporary fixing have a strength division higher than the strength division of the bolt 31 which comprises the drive wheel hub unit 1a. That is, at the time of temporary fixing, the bolts 31a and 31b are fastened to the screw hole 40 in an elastic region, and when the drive wheel hub unit 1a is assembled, the bolt 31 is fastened to the screw hole 40 in a plastic region to stabilize the axial force.

  When temporarily fixing the hub body 30 and the joint outer ring 3a, as shown in FIG. 5, a bolt 31c having a head portion 42b having a large outer diameter and a nut 47a having a large outer diameter are provided. It can also be used. That is, the inner surface in the axial direction of the head portion 42b of the bolt 31c is brought into contact with the outer surface in the axial direction of the pilot portion 49 existing at the outer end portion in the axial direction of the hub body 30, and the outer surface in the axial direction of the nut 47a. Then, the joint outer ring 3a is brought into contact with the inner end surface in the axial direction of the wall portion 34 of the mouse portion 17a. As a result, the hub body 30 and the joint outer ring 3a are clamped in the axial direction between the head portion 42b of the bolt 31c and the nut 47a. According to the method shown in FIG. 5, it is possible to prevent the screw hole 40 from being deformed or damaged at the time of temporary fixing.

[Second Example of Embodiment]
FIG. 6 shows a second example of the embodiment of the present invention. In the drive wheel hub unit 1b of the present example, the joint outer ring 3b has a cup-shaped mouth portion having a cylindrical wall portion 34 and a bottom portion 35 bent radially inward from the axially outer end portion of the wall portion 34. 17a and a shaft portion 19b extending axially outward from the center portion of the bottom portion 35. The shaft portion 19b has an inner ring raceway 9d on the inner side in the axial direction on the outer peripheral surface of the intermediate portion in the axial direction, and a second center hole 39a penetrating the central portion in the axial direction. The axially inner portion of the second center hole 39 a is a screw hole 40, and the axially outer portion of the second center hole 39 a is an engagement hole 50 having an inner diameter larger than the inner diameter of the screw hole 40. It has become. Further, the shaft portion 19b has a second face spline 21b which is an uneven surface in the circumferential direction on the outer end surface in the axial direction.

  The hub body 30a includes a large-diameter cylindrical portion 51 on the outer side in the axial direction, a small-diameter cylindrical portion 52 on the inner side in the axial direction, and a step portion 53 that connects the outer peripheral surface of the large-diameter cylindrical portion 51 and the outer peripheral surface of the small-diameter cylindrical portion 52. Is provided. The large-diameter cylindrical portion 51 has an axially outer inner ring raceway 9c on the outer peripheral surface of the axially inner portion, and a rotating flange 10a in the axially intermediate portion. The small diameter cylindrical portion 52 has an outer diameter slightly smaller than the fitting hole 50 of the second center hole 39a. Further, the step portion 53 is provided with a first face spline 16b which is an uneven surface in the circumferential direction.

  The hub main body 30a and the joint outer ring 3b fit the small-diameter cylindrical portion 52 into the fitting hole 50 without rattling in the radial direction, and mesh the first face spline 16b and the second face spline 21b. In this state, the inner member 25a is configured by being coupled and fixed by the bolt 31. The radial clearance between the outer peripheral surface of the small diameter cylindrical portion 52 and the inner peripheral surface of the fitting hole 50 is 5 μm with the central axis of the hub main body 30a and the central axis of the joint outer ring 3b aligned. It is as follows.

  According to the drive wheel hub unit 1b of the present example, similar to the drive wheel hub unit 1a of the first example of the embodiment, it is possible to reduce the size and weight, and to change the preload of the rolling element 6, and the hub. It is possible to prevent a decrease in the coupling strength between the main body 30a and the joint outer ring 3b and the occurrence of fretting wear at the meshing portion between the first face spline 16b and the second face spline 21b.

  The hub main body 30a constituting the drive wheel hub unit 1b of the present example is formed by hot forging the shape of the first face spline 16b and its peripheral portion, and then the first face spline 16b and The peripheral part can be formed by cold forging. That is, in general, a hub body having a rotating flange has a high degree of processing, and therefore, it is preferable to form by hot forging. Particularly in this example, after the approximate shape of the hub main body 30a including the small-diameter cylindrical portion 52 on the inner side in the axial direction is formed by hot forging, the first face spline 16b and its peripheral portion are formed by cold forging. Thus, the hub body 30a can be easily molded.

  On the other hand, the joint outer ring 3b constituting the drive wheel hub unit 1b of the present example does not have the small-diameter cylindrical part 37 on the outer side in the axial direction like the joint outer ring 3a of the first example of the embodiment. Even when the entire shape is formed by cold forging, the processing is not troublesome. The structure and operational effects of the other parts are the same as in the first example of the embodiment, including the method for grinding the outer peripheral surface of the inner member 25a.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Drive wheel hub unit 2 Hub unit bearing 3, 3a, 3b Joint outer ring 4 Outer ring 5 Hub 6 Rolling body 7a, 7b Outer ring raceway 8 Stationary flange 9a, 9b, 9c, 9d Inner ring raceway 10, 10a Rotating flange DESCRIPTION OF SYMBOLS 11 Hub main body 12 Inner ring 13 Small diameter step part 14 Center hole 15 Caulking part 16, 16a, 16b First face spline 17, 17a Mouse part 18 End wall part 19, 19a, 19b Shaft part 20 Screw hole 21, 21a, 21b First 2 face spline 22 bolt 23 joint inner ring 24 ball 25, 25a inner member 26 support hole 27 knuckle 28 through hole 29 mounting hole 30, 30a hub body 31, 31a, 31b, 31c bolt 32 first center hole 33 fitting Hole 34 Wall portion 35 Bottom portion 36 Large diameter tube portion 37 Small diameter tube portion 38 steps 39, 39a Second central hole 40 Screw hole 41 Escape recessed part 42, 42a, 42b Head 43a, 43b Cage 44 Internal space 45a, 45b Seal ring 46 Total grinding wheel 47, 47a Nut 48 Grinding stone 49 Pilot part 50 Fitting Hole 51 Large diameter cylinder part 52 Small diameter cylinder part 53 Step part

Claims (1)

An outer member having a double row outer ring raceway on the inner peripheral surface;
An inner member having a double row inner ring raceway on the outer peripheral surface;
Between the double-row outer ring raceway and the double-row inner ring raceway, a plurality of rolling elements arranged in a freely rotatable manner for each row,
The inner member includes a hub body, a joint outer ring, and a coupling member.
The hub body has an inner ring raceway on the outer side in the axial direction of the double row inner ring raceways on the outer circumferential surface of the axially intermediate portion, and has a rotating flange on the outer side in the axial direction and penetrates in the axial direction at the center. A first center hole, and a first face spline provided on a side surface present on the inner side in the axial direction from the inner ring raceway on the outer side in the axial direction,
The joint outer ring includes a shaft portion having an inner ring raceway on the inner side in the axial direction of the double row inner ring raceways on an outer peripheral surface in the axial direction, and a second center hole penetrating the central portion of the shaft portion in the axial direction. And having a second face spline on the side surface present on the axially outer side than the axially inner ring raceway,
The coupling member is inserted or screwed into the first center hole and the second center hole to couple and fix the hub body and the joint outer ring,
The first face spline and the second face spline mesh with each other, and the axially inner end of the hub body and the axially outer end of the joint outer ring are fitted,
Drive wheel hub unit.

Images