JP2012051393A - Rolling bearing unit for supporting wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a structure capable of keeping, in a high dimension, both of: the decrease in weight of an outer diameter side orbital ring member 3b and the securement of the strength and rigidity of a base end part of a rotational flange 12; and the securement of the form accuracy and dimensional accuracy of respective fitting holes 15a.SOLUTION: A radial-direction inner end part of the axial-direction inner side surface of the rotational flange 12 and an axial-direction outer end part of a recessed part 17 formed in an outer peripheral surface of the outer diameter side orbital ring member 3b are smoothly continued by a recessed and curved surface 19b having a cross sectional arc shape. The diameter D of the outer peripheral edge of the recessed and curved surface 19b is specified to be a diameter R of an inscribed circle of the respective fitting holes 15a or below. Reinforcing ribs 25 are respectively provided in positions sandwiching the fitting holes 15a and 15a from both sides in the circumferential direction, in a part between the radial-direction inner end part of the axial-direction inner side surface of the rotational flange 12 and the axial-direction outer end part of the recessed part 17 of the outer peripheral surface of the outer diameter side orbital ring member 3b.

Description

  This invention is a wheel support rolling bearing unit for rotatably supporting a vehicle wheel with respect to a suspension device, and the outer diameter side race ring member rotates without rotating the inner diameter side race ring member. With respect to the so-called outer ring rotating type, the present invention relates to an improvement in the structure intended to reduce the weight of the outer diameter side race ring member. Specifically, the outer diameter side race ring member is reduced in weight, the strength and rigidity of the base end portion of the rotary flange for supporting the wheel on the outer diameter side race ring member are secured, and the rotary flange is formed on the rotary flange. It is possible to realize a structure that can secure the shape accuracy and dimensional accuracy of the mounting hole in a high dimension.

  The outer ring rotating type rolling bearing unit for supporting the wheel can make the structure of the mounting part to the suspension device easier than that of the inner ring rotating type, so in some automobiles, the driven wheel (rear wheel of FF vehicle, FR It is used as a rolling bearing unit for supporting the front wheels of cars and MR cars. However, because the outer diameter side race ring member having a larger diameter than the inner diameter side race ring member is rotated, the moment of inertia is increased, and from the aspect of ensuring driving performance and fuel efficiency performance centering on acceleration performance, the inner ring rotation type This is disadvantageous compared to the rolling bearing unit for supporting wheels. In order to reduce or eliminate such disadvantages, it is effective to reduce the weight of the outer diameter side race ring member.

In order to reduce the weight of the outer diameter raceway ring member while ensuring the necessary performance as a wheel bearing rolling bearing unit, it is effective to adopt the following configurations (1) to (3) .
(1) Of the rolling elements arranged in a double row between the outer peripheral surface of the inner diameter side race ring member and the inner peripheral surface of the outer diameter side race ring member, the outer side in the axial direction The pitch circle diameter of the rolling elements in the row of the row in the assembled state is the inner side in the axial direction (inner with respect to the axial direction means the side that is the center in the width direction when assembled to the vehicle) It is made smaller than the pitch circle diameter of the rolling elements in the row.
(2) The outer diameter of the intermediate portion in the axial direction of the outer diameter side race ring member is also made smaller than the outer diameter of the portion near the inner end in the axial direction.
(3) In order to support and fix the wheel to the outer diameter side race ring member, the thickness in the axial direction of the rotary flange provided on the outer peripheral surface of the outer diameter side race ring member is thick at the necessary portion, and the others Thin the part.

Of these configurations shown in (1) to (3), (1) and (2) are described in Patent Document 1, for example.
As described in (1) above, by reducing the pitch circle diameter of the rolling elements in the outer row in the axial direction, the wheel is coupled and fixed to the outer diameter side race ring member. The diameter of the rotating flange provided on the outer peripheral surface can be kept appropriate (can be prevented from becoming excessive). Further, by increasing the pitch circle diameter of the rolling elements in the inner row in the axial direction, the moment rigidity of the rolling bearing unit for wheel support is ensured, and the running stability of a vehicle incorporating the rolling bearing unit for wheel support is secured. And durability of the wheel bearing rolling bearing unit can be ensured.
Further, as described in (2) above, the outer diameter side race ring member is made smaller than the outer diameter of the axially intermediate portion of the outer diameter side race ring member than the outer diameter of the portion near the inner end in the axial direction. The thickness in the radial direction can be prevented from becoming excessive, and the outer diameter side race ring member can be reduced in weight.
Further, the configuration (3) is described in Patent Document 2, for example. By reducing the thickness of the rotating flange having a relatively large outer diameter and a disk shape only at a necessary portion, the outer diameter side race ring member including the rotating flange can be reduced in weight. .

FIGS. 6-8 has shown an example of the conventional rolling bearing unit for wheel support provided with the structure like said (1)-(3). The wheel support rolling bearing unit 1 includes an inner diameter side race ring member 2, an outer diameter side race ring member 3, and a plurality of balls 4a and 4b, each of which is a rolling element.
Of these, the inner diameter side race ring member 2 is formed by coupling and fixing a main portion 5 and an inner ring element 6 fitted on the outer end in the axial direction of the main portion 5 by a caulking portion 7. The main part 5 and the inner ring element 6 are each made of an iron-based alloy such as medium carbon steel (in the case of the main part 5) and bearing steel (in the case of the inner ring element 6) that can be hardened by hardening. Inner ring raceways 8a and 8b are formed in the inner ring. Out of these inner ring raceways 8a and 8b, the outer circumference of the inner portion of the main portion 5 that is closer to the inner side in the axial direction than the outer diameter of the inner ring raceway 8a in the outer row in the axial direction formed on the outer circumferential surface of the inner ring element 6. The outer diameter of the inner ring raceway 8b in the inner row formed on the surface is large. Further, stationary flanges 9 are provided on the inner peripheral surface of the main portion 5 so as to protrude radially inward from the inner peripheral surface, and a plurality of circumferential positions of the stationary flange 9 (four in the illustrated example). Are provided with screw holes 10 and 10. In the state of use, such an inner diameter side raceway ring member 2 is screwed into the screw holes 10 and 10 with bolts through which through holes formed on a component member side of a suspension device such as a knuckle, and further tightened. It is supported and fixed to the suspension system and does not rotate.

  Further, the outer diameter side race ring member 3 is made of an iron-based alloy such as medium carbon steel that can be hardened by hardening, and is concentric with the inner diameter side race ring member 2 around the inner diameter side race ring member 2. Has been placed. In such an outer diameter side race ring member 3, double row outer ring raceways 11a and 11b are arranged on a part of the inner circumference surface facing both the inner ring raceways 8a and 8b, and an axially outer portion of the outer circumference surface. Each has a rotating flange 12. The inner diameters of these outer ring raceways 11a and 11b are matched with the outer diameters of both inner ring raceways 8a and 8b, so that the inner diameter of the outer ring raceway 11a in the axially outer row is larger than the inner diameter of the outer ring raceway 11b in the same axially inner row. small. Further, the rotating flange 12 has an uneven inner surface in the axial direction instead of a flat outer surface in the axial direction for supporting the wheel and the brake rotating body (disk or drum), 13 and thin portions 14 and 14 are alternately arranged in the circumferential direction. Of these, thick holes 13 and 13 are provided with mounting holes 15 and 15 for mounting a coupling member for coupling and fixing a wheel to the rotary flange 12 in a state of passing through the rotary flange 12 in the axial direction. ing. Each of the mounting holes 15 and 15 is a screw hole for screwing the male screw portion of the bolt when a bolt is used as the coupling member, and when the stud is used, the base of the stud is used. It is a through-hole for fitting the end part by interference fitting (serration engagement by press fitting). In any case, the mounting holes 15 and 15 have the same diameter, and the centers thereof exist on the single circumference concentric with the outer diameter side race ring member 3 at equal intervals in the circumferential direction. .

  The outer diameter side race ring member 3 as described above rotates together with the wheel coupled and fixed to the rotary flange 12 in the state of use. The thin portions 14 and 14 are formed with through holes 16 and 16 for weight reduction. Further, the outer diameter of the outer diameter side raceway ring member 3 is made smaller between the peripheral part and the rotary flange 12 than the peripheral part of the outer ring raceway 11b on the inner side in the axial direction. That is, the portion between these is a recessed portion (undercut portion) 17 having an outer diameter smaller than both axial side portions. By providing the recessed portion 17, it is possible to prevent the thickness in the radial direction of the axially intermediate portion of the outer diameter side race ring member 3 from becoming excessive, and to reduce the weight of the outer diameter side race ring member 3. I am trying. Note that both end portions in the axial direction of the recessed portion 17 are continuous with adjacent surfaces and curved surfaces. First, the outer end portion in the axial direction of the recessed portion 17 is smoothly continued by the inner surface in the axial direction of the rotary flange 12 and the concave curved surface 19 whose sectional shape is a quarter arc. Further, the axially inner end portion of the recessed portion 17 is continuous by a peripheral portion of the outer ring raceway 11b in the inner row and a concave curved surface 20 having a circular arc section in the outer peripheral surface of the outer diameter side raceway ring member 3. I am letting. The biconcave curved surfaces 19 and 20 have a concave cross-sectional shape with respect to the virtual plane including the central axis of the outer diameter side race ring member 3, but the cross-sectional shape with respect to the virtual plane orthogonal to the central axis is a convex arc. Of course there are.

The balls 4a and 4b are held in the cages 18a and 18b, respectively, in plural numbers for each row between the inner ring raceways 8a and 8b and the outer ring raceways 11a and 11b. It is provided so that it can roll freely. With the difference in diameter of each of the tracks 8a, 8b, 11a, 11b, the pitch circle diameter PCD _O of the balls 4a, 4a in the outer row is smaller than the pitch circle diameter PCD _I of the balls 4b, 4b in the inner row ( PCD _O <PCD _I ).
Further, among the openings at both ends of the internal space 21 where the balls 4a and 4b are installed, the axially outer end side is provided with a substantially bottomed cylindrical cap 22, and the axially inner end side thereof is a seal ring such as a combination seal ring. 23, respectively.

  Since the wheel support rolling bearing unit 1 as described above has all of the above-described configurations (1) to (3), while ensuring the necessary performance as the wheel support rolling bearing unit 1, It is easy to reduce the weight of the outer diameter side race ring member 3. However, in order to achieve both performance and weight reduction at a higher level, the inner diameter side end of the rotating flange 12 and the outer diameter side race ring member 3 with respect to the moment applied to the rotating flange 12 are used. It is necessary to reduce the thickness of the rotating flange 12 while ensuring the strength and rigidity of the continuous portion with the main body portion. For this purpose, there are the following problems. Hereinafter, this point will be described.

  The radial positions of the mounting holes 15, 15 formed at a plurality of locations in the circumferential direction of the rotating flange 12 (the pitch circle diameters of the mounting holes 15, 15) are wheels to be coupled and fixed to the rotating flange 12. It is regulated to some extent in relation to (wheel). Further, the inner diameters of the mounting holes 15 and 15 are regulated in relation to the outer diameters of the coupling members to be assembled in the mounting holes 15 and 15. Moreover, the outer diameter of each of these coupling members is restricted from the aspect of securing the coupling strength between the rotating flange 12 and the wheel. That is, the pitch circle diameter and the inner diameter of each of the mounting holes 15, 15 are almost determined if the vehicle to which the wheel bearing rolling bearing unit 1 is to be mounted is determined, and the degree of freedom in design is extremely limited.

  On the other hand, with the turning of the vehicle, a large moment is applied to the rotating flange 12 with the ground contact surface of the wheel (tire) as an input portion, and this moment is applied to the inner end of the rotating flange 12 and the outer end. It is necessary to support the radial side race ring member 3 at a continuous portion with the main body portion. Therefore, it is necessary to sufficiently increase the bending strength and bending rigidity of the continuous portion. In the case of the conventional structure shown in FIGS. 6 to 8, by increasing the radius of curvature of the concave curved surface 19 that connects the axially outer end portion of the concave portion 17 and the axially inner side surface of the rotary flange 12. The strength and rigidity of the continuous portion are ensured. That is, when the radius of curvature is small, a large stress is easily applied to the continuous portion by the moment. For this reason, when ensuring the reliability and durability of the wheel support rolling bearing unit 1, the weight reduction of the outer diameter side race ring member 3 due to the thinning of the rotating flange 12 is limited. Thus, by increasing the radius of curvature of the concave curved surface 19, the reliability and durability are ensured and the thickness is reduced.

  However, when the radius of curvature of the concave curved surface 19 is increased, as shown in FIG. 7, a part of each of the mounting holes 15, 15 (a portion closer to the inner end with respect to the radial direction of the rotating flange 12) becomes the concave curved surface 19. It will be in the state opened to a part of. As a result, the axial length of the inner peripheral surface of each of the mounting holes 15, 15 is not uniform over the entire circumference of the inner peripheral surface, and at the portion near the inner end with respect to the radial direction of the rotary flange 12. , It will be longer than the other parts. Each of the mounting holes 15 and 15 is formed by a cutting tool or a screw machining tool such as a drill, a reamer, a tap, or a rolling tap. As described above, the axial length of the inner peripheral surface of each of the mounting holes 15 and 15 is set. If the thickness is not uniform, a force in the bending direction is likely to be applied to the cutting tool or the screw machining tool during the machining. As a result, it is difficult not only to ensure the dimensional accuracy and shape accuracy of the obtained mounting holes 15, 15, but also to ensure the durability of the cutting tool. The reduction in the durability of the cutting tool leads to an increase in the manufacturing cost of the wheel support rolling bearing unit 1 including the outer diameter side race ring member 3. Further, in the case where each of the coupling members is a stud provided with a flange portion on the base plate portion, in order to prevent interference with the flange portion, there is a troublesome part of scraping off the concave surface portion 19.

  Ensuring the strength and rigidity of the continuous part between the inner diameter side end of the rotating flange and the main body part of the outer diameter side race ring member, and the axial dimension of each mounting hole is uniform over the entire circumference of each mounting hole Conventionally, the structures described in Patent Documents 3 to 5 are known as possible structures. 9 to 10 show an example of a conventional structure described in Patent Document 4 among them. In the case of this conventional structure, the large-diameter-side end of the partially conical cylindrical reinforcing member 24 is the outer peripheral edge of the rotary flange 12, and the small-diameter-side end is the outer flange of the outer-diameter-side race ring member 3a. Each of them is fixedly joined by welding to a portion closer to the axially inner side than 12. When the wheel support rolling bearing unit 1a shown in FIGS. 9 to 10 is used, if a moment is applied to the rotary flange 12 as the vehicle turns, the reinforcing member 24 supports the moment and rotates the rotation. It suppresses that the flange 12 bends with respect to the main-body part of the said outer diameter side bearing ring member 3a. For this reason, the outer diameter side race ring member 3a can be made thin, and the radius of curvature of the concave curved surface 19a that connects the axially outer end portion of the concave portion 17a and the axially inner side surface of the rotary flange 12 can be reduced. Further, the axial dimensions of the mounting holes 15a can be made uniform over the entire circumference of the mounting holes 15a, so that the accuracy of the mounting holes 15a and the durability of the cutting tool or screw machining tool can be ensured.

  However, in the case of the conventional structure shown in FIGS. 9 to 10 described above, since the reinforcing member 24 is provided, the processing cost, parts management cost, and assembly cost of the reinforcing member 24 increase. Moreover, as the reinforcing member 24 is welded and fixed to the outer diameter side raceway ring member 3a, the flatness of the rotary flange 12 is deteriorated, or the hardness of the outer ring raceway 11b in the inner row is lowered. The rolling fatigue life of the track 11b may be reduced.

  On the other hand, in Patent Documents 6 and 7, in order to ensure the strength of the flange formed on the outer peripheral surface of the outer diameter side race ring member, a plurality of gaps are provided between the outer peripheral surface of the outer diameter side race ring member and the side surface of the flange. The structure of a wheel bearing rolling bearing unit provided with reinforcing ribs is described. The invention described in Patent Document 6 out of both patent documents is directed to a wheel bearing rolling bearing unit of an inner ring rotating type, and the invention described in Patent Document 7 is a wheel supporting rolling of an outer ring rotating type. Intended for bearing units. However, in any structure, the pitch circle diameters of the rolling elements arranged in double rows are the same, and the outer diameter side ends of the reinforcing ribs are in the radial direction of the outer diameter side race ring member. , Which coincides with the outer peripheral edge of the flange or is present in the radially outer part from the outer peripheral edge. Further, the thickness of the flange is uniform except for the portions where the reinforcing ribs are provided. The structures of the inventions described in Patent Documents 6 and 7 are greatly different from the structures shown in FIGS. 6 to 8 which are the objects of the present invention.

JP 2008-275023 A JP 2008-55984 A German Patent Application Publication No. 10 2007 023 661 German Patent Application Publication No. 10 2007 060 627 German Patent Application Publication No. 10 2008 023 588 JP 2004-36818 A JP 2006-105304 A

  In view of the circumstances as described above, the present invention is to reduce the weight of the outer diameter side bearing ring member constituting the outer ring rotating type wheel support rolling bearing unit and to support the wheel on the outer diameter side bearing ring member. The invention has been invented to realize a structure in which securing of the strength and rigidity of the base end portion of the rotating flange and securing of the shape accuracy and dimensional accuracy of the mounting hole for assembling the coupling member can be arranged in a high dimension. .

The wheel bearing rolling bearing unit of the present invention includes an inner diameter side race ring member, an outer diameter side race ring member, and a plurality of rolling elements.
Among these, the inner ring side race ring member has a double row inner ring race track on the outer peripheral surface, and is supported and fixed to the suspension device in a use state and does not rotate. Of these inner ring raceways, the outer diameter of the inner ring raceway on the axially outer side is also smaller than the outer diameter of the inner ring raceway on the inner side in the axial direction.
The outer diameter side race ring member is disposed around the inner diameter side race ring member and concentrically with the inner diameter side race ring member. Further, a part of the inner peripheral surface has a double row outer ring raceway at a portion facing both the inner ring raceways, and a rotation flange at an axially outer portion of the outer peripheral surface. The inner diameter of the outer ring raceway on the outer side in the axial direction is smaller than the inner diameter of the outer ring raceway on the inner side in the axial direction. Further, the outer diameter of the outer diameter side race ring member is smaller in the portion between the peripheral portion and the rotary flange than the peripheral portion of the outer ring race on the inner side in the axial direction. In addition, the mounting holes for mounting the connecting members for connecting and fixing the wheel to the rotating flange are located at the same position in the radial direction at a plurality of circumferential positions of the rotating flange. It is provided in a penetrating state. Furthermore, the radially inner end of the axial inner surface of the rotating flange and the axially outer end of the intermediate portion of the outer peripheral surface of the outer race ring member are formed by a concave curved surface having a circular arc cross section. Smooth and continuous. And the said outer diameter side track ring member rotates with the wheel couple | bonded and fixed to the said rotation flange in the use condition.
Further, a plurality of the rolling elements are provided for each row between the inner ring raceways and the outer ring raceways. And the said outer diameter side bearing ring member is rotatably supported around the said inner diameter side bearing ring member.

In particular, in the wheel bearing rolling bearing unit of the present invention, the diameter of the outer peripheral edge of the concave curved surface is set to be equal to or smaller than the diameter of the inscribed circle of each mounting hole.
Then, a plurality of reinforcing ribs are provided at positions that sandwich the mounting holes from both sides in the circumferential direction between the radially inner end of the axially inner side surface of the rotating flange and the outer circumferential surface of the outer diameter side race ring member. These are provided so as to protrude inward in the axial direction from the inner side surface and radially outward from the outer peripheral surface, respectively.

When implementing the wheel bearing rolling bearing unit of the present invention as described above, more specifically, as in the invention described in claim 2, the outer diameter side race ring member is forged into an iron-based alloy. Shall be made. In addition, thick portions and thin portions are arranged alternately in the circumferential direction on the rotating flange, and the mounting holes and the reinforcing ribs are connected to the inner surface in the axial direction of the thick portion and the outer peripheral surface. Provide between.
More specifically, as in the invention described in claim 3, the axially outer ends of the respective reinforcing ribs are smoothly connected to the inner surface of the rotating flange. And the continuous part of the radial direction outer end part of each of these reinforcement ribs and this inner surface exists on the inner side in the radial direction than the pitch circle of each said mounting hole.
Or like the invention described in Claim 4 or Claim 5, the axial direction inner end part of each said reinforcement rib is made to continue smoothly with the outer peripheral surface of the said outer diameter side track ring member. And the continuous part of the axial direction inner end part of each said reinforcing rib and the outer peripheral surface of this outer diameter side bearing ring member is set to the axially inner side of the shoulder part of the outer ring raceway outside the axial direction (described in claim 4). In the case of the invention) or outside (in the case of the invention described in claim 5).

  According to the present invention configured as described above, it is possible to reduce the weight of the outer diameter side bearing ring member constituting the outer ring rotating type wheel support rolling bearing unit and to support the wheel on the outer diameter side bearing ring member. Ensuring the strength and rigidity of the base end portion of the rotating flange and ensuring the shape accuracy and dimensional accuracy of the mounting hole for assembling the coupling member can be arranged side by side in a high dimension. The reason will be described below.

  In the case of the outer diameter side bearing ring member constituting the wheel bearing rolling bearing unit of the present invention, the reinforcing ribs are provided at positions sandwiching the mounting holes from both sides in the circumferential direction. The moment rigidity of the rotary flange with holes is improved. For this reason, the thickness of the rotating flange in the axial direction is not particularly increased, and the curvature of the concave curved surface existing in the continuous portion between the axial inner surface of the rotating flange and the outer peripheral surface of the outer diameter side raceway ring member. Even if the radius is reduced, the moment rigidity can be secured. Then, the diameter of the outer peripheral edge of the concave curved surface is set to be equal to or smaller than the diameter of the inscribed circle of each mounting hole, and the axial length of the inner peripheral surface of each mounting hole is extended over the entire circumference of the inner peripheral surface. Can be uniform. As a result, it becomes difficult to apply a force in the bending direction to the cutting tool that processes each of the mounting holes, and it is possible to ensure the shape accuracy and dimensional accuracy of each of the mounting holes and to ensure the durability of the cutting tool.

In particular, according to the invention described in claim 2, the weight of the rotating flange can be reduced in a higher dimension.
Further, according to the invention described in claim 3, it is not necessary to make each of the reinforcing ribs unnecessarily bulky, and the outer diameter side bearing ring member including these reinforcing ribs can be reduced in weight in a higher dimension. I can plan.

  Further, the outer diameter side bearing ring member constituting the rolling bearing unit for supporting a wheel of the present invention has an outer diameter at the intermediate portion in the axial direction smaller than the outer diameters at both side portions. When forging is made by forging, a diameter expansion process is required to increase the diameter of the inner end in the axial direction. In this diameter expansion process, it is conceivable that the outer peripheral surface of the axially intermediate portion or inner end portion of the outer diameter side bearing ring member is suppressed by a backup mold or not. In any case, in the diameter expansion step, the diameter expansion punch is pushed into the inner end portion in the axial direction of the intermediate material to increase the diameter of the inner end portion in the axial direction. During the diameter expansion process, the intermediate material is not limited to the portion where the diameter-expansion punch has been pushed in, but the portion that should be expanded, and the portion that is adjacent to the portion that should be expanded in the axial direction and should not be expanded. In addition, an extra force directed radially outward is applied. Regardless of such extra force, it is necessary to consider that the radial dimension of the portion that should not be expanded does not change.

As in the invention described in claim 4, the axial position of the continuous portion between the axial inner end of each reinforcing rib and the outer peripheral surface of the outer diameter side race ring member is defined as the shoulder of the outer race track on the outer side in the axial direction. If it exists in the axial direction inside of a part, even if it does not use the said backup type | mold, it can suppress that the dimension of the said part which should not be diameter-expanded changes with the pushing of the said diameter-expansion punch.
On the other hand, as in the invention described in claim 5, the axial position of the continuous portion between the axial inner end portion of each reinforcing rib and the outer peripheral surface of the outer diameter side race ring member is defined as the axial outer side. When the backup type is used, it is possible to eliminate the trouble of matching the phase in the circumferential direction between the backup type and the outer diameter side race ring member when the backup type is used.

Sectional drawing which shows one example of embodiment of this invention. The half part sectional view which takes out and shows an outer diameter side race ring member similarly. The A section enlarged view of FIG. 2 similarly. The perspective view similarly shown in the state which took out the outer diameter side bearing ring member and was seen from the axial direction inner side. The half section view which simplifies a part for explaining the process of enlarging the axial direction inner end part of an intermediate material, and making it the outside diameter side race ring member provided with the concave part. The perspective view which shows one example of the conventional structure in the state seen from the axial direction inner side. Similarly sectional drawing. The perspective view shown in the state which took out the outer ring raceway member and was seen from the axial direction inner side. Sectional drawing which shows one example of the structure known conventionally. Similarly, the perspective view shown in the state seen from the axial direction inner side.

  1 to 5 show an example of an embodiment of the present invention. The characteristics of the present invention including this example are that the outer diameter side race ring member 3b constituting the outer ring rotating type wheel support rolling bearing unit 1b is reduced in weight, and the outer diameter side race ring member 3b is provided with a wheel. In order to ensure that the strength and rigidity of the base end of the rotating flange 12 for supporting and securing the shape accuracy and dimensional accuracy of the mounting holes 15a and 15a for assembling the coupling members are aligned in a high dimension, This is in that the shape of the continuous portion between the outer peripheral surface of the radial side ring member 3b and the inner surface in the axial direction of the rotary flange 12 is devised. Since the structure and operation of the other parts are the same as those of the previous structure shown in FIGS. 6 to 8 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. The description will focus on the features of the example.

  Also in the case of the wheel support rolling bearing unit 1b of this example, as in the case of the previous structure, the continuous portion between the outer peripheral surface of the outer diameter side race ring member 3b and the axial inner surface of the rotary flange 12 is provided. A concave curved surface 19b having a cross-sectional shape of a quarter arc is formed. Both ends of the generatrix of the concave curved surface 19b, the generatrix of the outer peripheral surface of the outer diameter side race ring member 3b, and the generatrix of the inner surface in the axial direction of the rotary flange 12 are respectively tangential to the generatrix of the concave curved surface 19b. Smooth and continuous. In particular, in the case of the wheel-supporting rolling bearing unit 1b of the present example, the radius of curvature of the cross-sectional shape of the concave curved surface 19b is made sufficiently smaller than the radius of curvature of the cross-sectional shape of the conventional structure, and the concave curved surface. The width dimension of 19b (particularly, the height h in the radial direction of the outer diameter side race ring member 3b) is reduced. The diameter D of the outer peripheral edge of the concave curved surface 19b is set to be equal to or smaller than the diameter R of the inscribed circle of the mounting holes 15a and 15a (D ≦ R).

  The outer diameter side race ring member 3b is formed by forging an iron-based alloy such as medium carbon steel, and the disk-shaped rotating flange 12 is formed on the outer peripheral surface of the outer peripheral portion in the axial direction. ing. In the same manner as in the previous structure, the rotating flange 12 has an axially inner side surface having an uneven shape instead of a flat outer surface in the axial direction, and the thick portions 13 and 13 and the thin portions 14 and 14 are Alternatingly arranged in the circumferential direction. Regarding the width dimension in the circumferential direction, each of the thick portions 13 and 13 is widest at the radially inner end, and gradually decreases toward the radially outer side. That is, the shape of each of these thick portions 13, 13 viewed from the axial direction of the outer diameter side race ring member 3 b is a substantially isosceles triangle shape with a rounded top. Each of the mounting holes 15a, 15a is in a state of penetrating the rotary flange 12 in the axial direction at the radially outer end portion (the vicinity of the top portion) in the circumferential intermediate portion of the thick portions 13, 13. Provided.

  On the other hand, of the inner side surface in the axial direction of the rotating flange 12, the thick end portions 13, 13 are formed at the base end portions (the radially inner end portions of the rotating flange 12). Reinforcing ribs 25, 25 are formed at positions sandwiching the mounting holes 15a, 15a from both sides in the circumferential direction, respectively. Each of the reinforcing ribs 25 and 25 has a shape that protrudes axially inward from the axial inner surface of the rotary flange 12 and radially outward from the outer peripheral surface of the outer diameter side race ring member 3b. . Further, the height dimension, which is a protruding amount radially outward from the outer peripheral surface of the outer diameter side race ring member 3b, gradually decreases toward the inner side in the axial direction. The axially outer end portions of the reinforcing ribs 25 and 25 are smoothly continuous with the inner surface of the rotating flange 12, and the axially inner end portion is continuously continuous with the outer peripheral surface of the outer diameter side race ring member 3b. . That is, the shape (the shape seen from the circumferential direction) of the ridges of each of the reinforcing ribs 25, 25 has a shape in which partial arc portions are arranged at both ends of the linear portion, as shown in FIGS. The end portions of both the partial arc portions, the inner side surface and the outer peripheral surface are smoothly continuous in the tangential direction of the both partial arc portions.

A continuous portion between the radially outer end portion of each of the reinforcing ribs 25 and 25 and the inner surface of the rotating flange 12 exists inside the pitch circle of the mounting holes 15a and 15a in the radial direction. The continuous portion between the radially outer end of each of the reinforcing ribs 25 and 25 and the inner surface of the rotary flange 12 refers to a connecting portion between the end of the partial arc portion and the inner surface. Therefore, the diameter D ₂₅ of the circumscribed circle of the reinforcing ribs 25, ₂₅ is equal to or less than the diameter PCD ₁₅ of the pitch circle of the mounting holes 15a, 15a (D ₂₅ ≦ PCD ₁₅ ). The radial position is restricted within a range in which a reinforcing function by the reinforcing ribs 25 and 25 can be secured and the volume of the reinforcing ribs 25 and 25 is not excessive. The positions of the inner end portions in the axial direction of the reinforcing ribs 25 and 25 are restricted in relation to the processing step of the outer diameter side race ring member 3b. This point will be described later.

  As described above, the outer diameter side bearing ring member 3b constituting the wheel support rolling bearing unit 1b of the present example has the mounting holes 15a at positions where the mounting holes 15a and 15a are sandwiched from both sides in the circumferential direction. , A pair of reinforcing ribs 25 are provided for each 15a. For this reason, the moment rigidity of the rotary flange 12 provided with the mounting holes 15a and 15a is improved by the reinforcing ribs 25 and 25. As a result, the thickness of the rotating flange 12 in the axial direction is not particularly increased, and the axial thickness of the rotating flange 12 and the outer peripheral surface of the outer diameter side race ring member 3b are present in a continuous portion. Even if the curvature radius of the concave curved surface 19b is reduced, the moment rigidity can be secured. In the case of this example, the rotating flange 12 is composed of the thick portions 13 and 13 and the thin portions 14 and 14, but the thickness of each of the thick portions 13 and 13 is the same. Even if the dimensions are not particularly increased, the moment rigidity can be ensured even if the thickness dimensions of the thin wall portions 14 and 14 are further reduced.

For this reason, even if it considers providing the said each reinforcing ribs 25 and 25, sufficient weight reduction can be achieved. That is, the diameter D ₂₅ of the circumscribed circle of each of the reinforcing ribs 25, ₂₅ is equal to or less than the diameter PCD ₁₅ of the pitch circle of the mounting holes 15a, 15a, so that the reinforcing ribs 25, 25 are unnecessarily bulky. You do n’t have to. That is, moment is applied to the rotary flange 12 from a connecting member such as a stud or a bolt attached to the mounting holes 15a and 15a when the vehicle equipped with the wheel bearing rolling bearing unit 1b is turned. Based on this moment, a large tensile stress is applied to an inward portion of each of the mounting holes 15a, 15a in the radial direction of the rotating flange 12. Regardless of such tensile stress, it is necessary to ensure the rigidity of the inward portion in the radial direction of the rotating flange 12 in order to prevent the occurrence of damage such as cracks in a part of the rotating flange 12. is there. In particular, when the coupling member is a bolt and each of the mounting holes 15a, 15a is a screw hole, it is important to ensure the rigidity of the inward portion in order to prevent cracks from the groove bottom of the female screw. Become. On the other hand, even if the reinforcing ribs 25 are provided up to the outer diameter side of the pitch circle of the mounting holes 15a, 15a, the effect of further improving the durability of the rotating flange 12 cannot be expected. In the case of this example, the range in which the reinforcing ribs 25 and 25 are formed is regulated as described above. Therefore, the volume of the reinforcing ribs 25 and 25 is suppressed to the necessary minimum, and the outer diameter side raceway ring is reduced. The weight of the member 3b can be reduced in a higher dimension.

  As described above, in the case of the outer diameter side bearing ring member 3b incorporated in the wheel supporting rolling bearing unit 1b of this example, the radius of curvature of the concave curved surface 19b is reduced while ensuring the moment rigidity of the rotating flange 12. Thus, the diameter D of the outer peripheral edge of the concave curved surface 19b is set to be equal to or smaller than the diameter R of the inscribed circle of the mounting holes 15a and 15a. Therefore, both ends of each of the mounting holes 15a, 15a are opened in substantially flat portions of the both side surfaces in the axial direction of the rotary flange 12 that are substantially parallel to each other. Accordingly, the axial length of the inner peripheral surface of each of the mounting holes 15a, 15a can be made uniform over the entire circumference of the inner peripheral surface. As a result, it becomes difficult to apply a force in a bending direction to a cutting tool or a screw machining tool such as a drill, a reamer, a tap, a rolling tap, or the like that processes each of the mounting holes 15a, 15a, and the shape of the mounting holes 15a, 15a. While ensuring accuracy and dimensional accuracy, the durability of the cutting tool can be secured.

  When the mounting holes 15a and 15a are screw holes, the end portions of the screw grooves are not exposed to a part of the concave curved surface 19b. For this purpose, assuming that each of the mounting holes 15a and 15a is a circular hole having an inner diameter of the groove bottom diameter of the female screw, the diameter of the inscribed circle of each of the mounting holes 15a and 15a is set, and the concave curved surface 19b is set. The diameter of the outer peripheral edge is set to be equal to or smaller than the diameter of the set inscribed circle. The reason for this is that the bottom of the thread groove, which has a large curvature and is likely to concentrate stress, is prevented from being exposed to the concave curved surface 19b, and the possibility that a crack starting from the bottom of the thread groove will occur. It is for lowering.

  In the outer diameter side race ring member 3b, the outer diameter of the recessed portion 17 existing in the axially intermediate portion is smaller than the outer diameters of both side portions. For this reason, when the outer diameter side race ring member 3b is manufactured by forging, a diameter expansion step of expanding the diameter of the inner end in the axial direction is required. In this diameter expansion process, as shown in FIG. 5, there are a case where the outer peripheral surface of the axially intermediate portion or inner end portion of the outer diameter side race ring member 3b is suppressed by the backup die 26 and a case where it is not suppressed. Conceivable. In any case, in the diameter expansion step, the diameter expansion punch 27 is pushed into the inner end portion of the intermediate material 28 in the axial direction, and the diameter of the inner end portion in the axial direction is expanded. During the diameter expansion process, the intermediate material 28 faces not only the portion where the diameter expansion punch 27 is pushed, but also the portion adjacent to the axial direction that should not be expanded in the radial direction. Extra power is added. Regardless of such extra force, the portion of the intermediate material 28 that should not be expanded (in particular, the double row outer ring raceways 11a and 11b formed on the inner peripheral surface of the outer diameter side race ring member 3b). It is necessary to consider that the radial dimension of the outer ring raceway 11a portion of the outer row and the outer ring raceway portion 11a in the radial direction of the outer ring raceway 11a does not change.

  In order to minimize harmful deformation caused by the pressing of the diameter-expanding punch 27 and to minimize the machining allowance during finishing, it is preferable to use the backup die 26. However, this back-up mold 26 must be removed from the periphery of the workpiece after processing, and can be divided into a plurality of elements in the circumferential direction, and must not be able to support a large force applied radially outward during processing. Because it does not become, equipment cost increases. In order to omit such a backup mold 26 and keep the manufacturing cost low, it is necessary to devise the structure on the intermediate material 28 side to suppress the harmful deformation.

  Therefore, when the backup mold 26 is omitted, the axial position of the continuous portion between the axial inner ends of the reinforcing ribs 25 and 25 and the outer peripheral surface of the outer diameter side race ring member 3b is increased. It is as close as possible to the portion where the diameter is expanded by the diameter punch 27. Specifically, it is present on the inner side in the axial direction of the shoulder portion 29 of the outer ring raceway 11a in the outer row (a position in FIG. 5 or the right side in FIG. 5). In this way, if the axially inner end portions (the continuous portions) of the respective reinforcing ribs 25, 25 are present on the inner side in the axial direction of the shoulder portion 29, which is close to the portion to be expanded in diameter, the expanded diameter is increased. The rigidity in the radial direction of the portion that should not be increased can be increased. As a result, even if the backup die 26 is not used, it is possible to suppress a change in the size of the portion that should not be expanded as the diameter expanding punch 27 is pushed.

  On the other hand, when the backup mold 26 is used, the axial position of the continuous portion between the axial inner end of each of the reinforcing ribs 25 and 25 and the outer peripheral surface of the outer diameter side race ring member 3b is determined. , And away from the diameter-enlarged portion by the diameter-enlarging punch 27. Specifically, it is present on the outer side in the axial direction of the shoulder portion 29 (the position in FIG. 5 or the left side in FIG. 5). When the backup mold 26 and the reinforcing ribs 25 and 25 overlap each other in the radial direction, it is necessary to match the phases of the backup mold 26 and the outer diameter side race ring member 3b in the circumferential direction. On the other hand, if the axial position of the continuous portion is set to the lower position in FIG. 5 or outside in the axial direction, the backup mold 26 and the reinforcing ribs 25 and 25 do not overlap in the radial direction, There is no need to match the phases.

  When implementing this invention, it is preferable from the surface which obtains the effect of this invention fully that each attachment hole 15a, 15a is made into a screw hole, and each connection member is made into a volt | bolt. However, the mounting holes 15a, 15a can be simply circular holes, and the connecting members can be studs having flanges at their base ends. In this case, the shape of the collar portion is not a simple circle but a shape that does not interfere with the reinforcing ribs 25 and 25.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Rolling bearing unit for wheel support 2 Inner diameter side ring member 3, 3a, 3b Outer diameter side ring member 4a, 4b Ball 5 Main part 6 Inner ring element 7 Caulking part 8a, 8b Inner ring raceway 9 Static flange 10 Screw hole 11a, 11b Outer ring raceway 12 Rotating flange 13 Thick part 14 Thin part 15, 15a Mounting hole 16 Through hole 17, 17a Recessed part 18a, 18b Retainer 19, 19a, 19b Recessed curved surface 20 Recessed curved surface 21 Internal space 22 Cap 23 Seal Ring 24 Reinforcement Member 25 Reinforcement Rib 26 Backup Type 27 Expanding Punch 28 Intermediate Material 29 Shoulder

Claims (5)

  An inner ring raceway member having a double-row inner ring raceway on the outer peripheral surface, which is supported and fixed to the suspension device in use and does not rotate, and is arranged around the inner diameter raceway ring member concentrically with the inner diameter raceway ring member A part of the inner peripheral surface has a double-row outer ring raceway in the part facing both inner ring raceways and a rotary flange in the axially outer part of the outer peripheral surface, and is connected to this rotary flange in use. An outer-diameter-side race ring member that rotates together with fixed wheels, and a plurality of rolling elements provided in each row between the inner ring raceways and the outer ring raceways. The outer diameter of the inner ring raceway on the outer side in the axial direction is smaller than the outer diameter of the inner ring raceway on the inner side in the axial direction, and the inner diameter of the outer ring raceway on the outer side in the axial direction is the inner diameter of the outer ring raceway on the inner side in the axial direction. Smaller than the outer diameter of the outer ring member. It is smaller than the peripheral part of the outer ring raceway on the inner side in the direction, and the part between this peripheral part and the rotating flange. A mounting hole for mounting a coupling member for coupling and fixing the wheel to the flange is provided in a state of passing through the rotating flange in the axial direction, and a radially inner end of an axial inner surface of the rotating flange; In the wheel support rolling bearing unit in which the outer circumferential surface of the outer diameter side race ring member is smoothly continuous with the axially outer end portion of the intermediate portion by a concave curved surface having a circular arc cross section. The diameter of the outer peripheral edge of the curved surface is equal to or less than the diameter of the inscribed circle of each of the mounting holes, and is between the radial inner end of the axial inner surface of the rotating flange and the outer peripheral surface of the outer raceway ring member. Each mounting hole on both sides in the circumferential direction A rolling bearing unit for supporting a wheel, characterized in that a plurality of reinforcing ribs are provided at positions sandwiched between the inner side surface and the inner surface in an axially inward direction and from the outer peripheral surface in a radially outward direction. .   The outer diameter side race ring member is formed by forging an iron-based alloy, and the thick portion and the thin portion are alternately arranged in the circumferential direction on the rotating flange. The wheel support rolling bearing unit according to claim 1, wherein the mounting hole and the reinforcing ribs are provided between the axially inner side surface of the thick portion and the outer peripheral surface.   An axial outer end portion of each reinforcing rib is smoothly continuous with an inner surface of the rotating flange, and a continuous portion between the radially outer end portion of each reinforcing rib and the inner surface is the mounting hole. The rolling bearing unit for supporting a wheel according to claim 2, wherein the rolling bearing unit is present on the inner side in the radial direction than the pitch circle.   The axial inner end of each reinforcing rib is smoothly continuous with the outer peripheral surface of the outer diameter side race ring member, and the axial inner end of each reinforcing rib and the outer circumference of the outer diameter side race ring member The wheel bearing rolling bearing unit according to claim 3, wherein an axial position of a continuous portion with the surface is present on an axially inner side of a shoulder portion of the outer ring raceway on the outer side in the axial direction.   The axial inner end of each reinforcing rib is smoothly continuous with the outer peripheral surface of the outer diameter side race ring member, and the axial inner end of each reinforcing rib and the outer circumference of the outer diameter side race ring member The wheel support rolling bearing unit according to claim 3, wherein an axial position of a continuous portion with the surface is present on an axially outer side of a shoulder portion of the outer ring raceway on the outer side in the axial direction.

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