JP2008275023A - Hub unit bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hub unit bearing of an outer ring rotation type having simplified bearing construction for reducing the weight and cost of the bearing and improving the life of the bearing while reducing the pilot diameter of a hub flange. <P>SOLUTION: The hub unit bearing 10 comprises an outside member 11 having the hub flange 14 at the end on the outside in a vehicle cross direction, an inside member 12 having a knuckle mounting flange 17 at the end on the inside in the vehicle cross direction, and rolling elements 13 rollingly arranged between the outside member 11 and the inside member 12. The inside member 12 has a shaft portion 16 on which an inner ring raceway surface 12a on the inside in the vehicle cross direction and the knuckle mounting flange 17 are formed, and an inner ring 19 which is fitted to the end of the shaft portion 16 on the outside in the vehicle cross direction and on which an inner ring raceway surface 12a on the outside in the vehicle cross direction is formed. The pitch circle diameter of a train of rolling elements 13 on the inside in the vehicle cross direction is larger than the pitch circle diameter of a train of rolling elements 13 on the outside in the vehicle cross direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hub unit bearing of an outer ring rotating type having a double row bearing portion, and more particularly to a hub unit bearing for a driven wheel and having different pitch circle diameters of each rolling element row.

  As a conventional outer ring rotation type hub unit bearing, there is one in which the pitch circle diameter of the rolling element row on the outer side in the vehicle width direction is larger than the pitch circle diameter of the rolling element row on the inner side in the vehicle width direction. However, in this case, the pilot diameter of the hub flange of the outer ring (outer member) to which the wheel and the brake rotor are attached is increased.

  On the other hand, as a conventional inner ring rotation type hub unit bearing, there is one in which the pitch circle diameter of the rolling element row inside in the vehicle width direction is larger than the pitch circle diameter of the rolling element row outside in the vehicle width direction (for example, Patent Document 1). And 2). In this case, since the hub flange is arranged on the inner ring side, it is possible to avoid an increase in the pilot diameter of the hub flange and to increase the load capacity on the inner side in the vehicle width direction, thereby improving the bearing life. can do.

US Pat. No. 6,036,371 JP-A-11-240306

  However, in the hub unit bearings described in Patent Documents 1 and 2, it is difficult to insert the fixed-side inner member having the inner ring raceway surface into the outer ring, so the inner member has a split structure. In this case, in the hub unit bearing for the drive wheel, the inner member divided by the constant velocity joint can be fastened. However, in the hub unit bearing for the driven wheel, the divided inner member A member for fastening is separately required. This complicates the bearing structure and increases the weight and manufacturing cost of the bearing.

  The present invention has been made to eliminate such inconveniences, and its object is to reduce the pilot diameter of the hub flange, simplify the bearing structure, and reduce the weight and cost of the bearing. It is an object of the present invention to provide an outer ring rotation type hub unit bearing that can improve the bearing life.

The above object of the present invention is achieved by the following configurations.
(1) A cylindrical outer member having a double-row outer ring raceway surface on the inner peripheral surface and having a hub flange at an outer end in the vehicle width direction and constituting a rotating wheel is disposed adjacent to each other in the axial direction. A hub unit bearing comprising a pair of inner members having an inner ring raceway surface on an outer peripheral surface, and rolling elements arranged to be able to roll in a circumferential direction between the outer ring raceway surface and the inner ring raceway surface. The hub unit bearing is characterized in that the pitch circle diameter of the rolling element row on the inner side in the vehicle width direction is larger than the pitch circle diameter of the rolling element row on the outer side in the vehicle width direction.
(2) A cylindrical outer member having a double-row outer ring raceway surface on the inner peripheral surface and having a hub flange at the outer end in the vehicle width direction to form a rotating wheel, and a double-row inner ring on the outer peripheral surface An inner member having a raceway surface and having a knuckle mounting flange at an inner end in the vehicle width direction, and a rolling element disposed between the outer ring raceway surface and the inner ring raceway surface so as to be capable of rolling in a circumferential direction. The inner member is fitted to the shaft portion on which the inner ring raceway surface on the inner side in the vehicle width direction is formed and the knuckle mounting flange is formed, and the end portion on the outer side in the vehicle width direction of the shaft portion, A hub unit bearing having an inner ring raceway surface on the outer side in the vehicle width direction, the pitch circle diameter of the rolling element row on the inner side in the vehicle width direction being greater than the pitch circle diameter of the rolling element row on the outer side in the vehicle width direction. Hub unit bearing characterized by an increase in size.
(3) The inner ring is caulked and fixed to the shaft part, and the shaft part is made of a spheroidized annealed carbon steel billet for mechanical structure, formed by cold hermetic forging, without annealing after forging, The hub unit bearing according to (2), wherein the base portion of the knuckle mounting flange is assembled in a harder state than the shaft end portion before caulking.
(4) The shaft part is made of an annular billet made of carbon steel for machine structure that has been spheroidized and annealed. The billet is formed by cold hermetic forging, and a flange for knuckle mounting is formed by side extrusion. The hub unit bearing according to (2) or (3), wherein at least the flange surface is not machined.
(5) The shaft portion is quenched and tempered by electromagnetic induction without machining after cold hermetic forging, and the outer ring surface, which is a non-heat treated surface on the cold forged surface, is supported by a shoe, The hub unit bearing according to (3) or (4), which is ground.
(6) The outer member is made of an annular billet made of carbon steel for mechanical structure that has been spheroidized and annealed, and the outer peripheral surface and inner peripheral surface are formed by cold hermetic forging. The hub unit bearing according to any one of (1) to (5), wherein a hub flange is formed and at least an outer peripheral surface and a flange surface are not machined.
(7) The outer member has its outer ring raceway surface hardened and tempered by electromagnetic induction without being machined after cold hermetic forging, and the outer peripheral portion, which is a non-heat treated surface on the cold forged surface, is ground with a shoe. The hub unit bearing according to (6), characterized in that:
(8) The hub unit bearing according to any one of (1) to (7), wherein the outer member is formed by expanding an inner end portion in a vehicle width direction from a forged finished shape.

  According to the hub unit bearing of the present invention, since the pitch circle diameter of the rolling element row on the inner side in the vehicle width direction is larger than the pitch circle diameter of the rolling element row on the outer side in the vehicle width direction, the pilot diameter of the hub flange can be reduced. It is possible to simplify the bearing structure, reduce the weight and cost of the bearing, and improve the bearing life.

  Hereinafter, each embodiment of the hub unit bearing according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
First, with reference to FIG.1 and FIG.2, 1st Embodiment of the hub unit bearing which concerns on this invention is described.
FIG. 1 is a cross-sectional view of a main part for explaining a first embodiment of a hub unit bearing according to the present invention, and FIG. 2 is a cross-sectional view of a main part for explaining a modification of the hub unit bearing of the first embodiment. .

  As shown in FIG. 1, the hub unit bearing 10 of the present embodiment is for an outer ring rotating type driven wheel, and has an outer peripheral raceway surface 11a, 11a on the inner peripheral surface and constituting the rotating wheel. A ball (not shown) that can be rolled in the circumferential direction between the member 11, the inner member 12 having double-row inner ring raceway surfaces 12a, 12a on the outer circumferential surface, and the outer ring raceway surface 11a and the inner ring raceway surface 12a. Rolling elements) 13.

  The outer member 11 is a cylindrical member, and is a hub flange that extends radially outward to an end portion on the outboard side of the outer peripheral surface (an end portion on the outer side in the vehicle width direction in the assembled state in the automobile: the left end portion in FIG. 1). 14 A plurality of hub bolts 15 for mounting a wheel (not shown), a brake rotor, and the like that constitute a wheel are implanted in the hub flange 14 at substantially equal intervals in the circumferential direction.

  The inner member 12 has a shaft portion 16 on which an inboard-side inner ring raceway surface 12a is formed on the outer peripheral surface, and the inboard-side end portion of the outer peripheral surface of the shaft portion 16 (in the vehicle width direction in an assembled state in an automobile) A knuckle mounting flange 17 extending radially outward is formed at the inner end (right end in FIG. 1). A small-diameter step 18 is formed at the end of the outer peripheral surface of the shaft portion 16 on the outboard side, and an inner ring on which an outboard-side inner raceway surface 12a is formed on the outer peripheral surface of the small-diameter step 18. 19 is fitted. The inner ring 19 is fixed to the shaft portion 16 by caulking the end portion on the outboard side of the shaft portion 16. In the present embodiment, the inner ring 19 is fixed to the shaft portion 16 by caulking, but instead, the inner ring 19 may be fixed to the shaft portion 16 by screw fastening.

  In this embodiment, the outer ring raceway surface 11a on the inboard side of the outer member 11 is formed to have a larger diameter than the outer ring raceway surface 11a on the outboard side, and the inner ring raceway surface 12a of the shaft portion 16 on the inboard side is out. The board-side inner ring 19 is formed to have a larger diameter than the inner ring raceway surface 12a, and the pitch circle diameter (PCD) of the inboard-side ball 13 row is larger than the pitch circle diameter of the out-board side ball 13 row.

  Here, the outer member 11 is made of an annular billet made of carbon steel for mechanical structure that has been subjected to spheroidizing annealing, and the outer peripheral surface and the inner peripheral surface are formed by cold hermetic forging. The hub flange 14 may be formed at The hub flange 14 is preferably a so-called star flange in which a plurality of flange pieces are arranged in the circumferential direction of the outer member 11. Further, a cylindrical surface for applying a shoe when the outer ring raceway surface 11a is ground is formed on the outer peripheral portion of the outer member 11.

  Further, since the end surface of the hub flange 14 is an accurate flat surface, it may be used as a reference surface for grinding the outer ring raceway surface 11a together with the shoe without annealing after forging and without machining. The outer ring raceway surface 11a needs to be induction hardened (quenching and tempering by an electromagnetic induction method), but the end surface of the hub flange 14 and the cylindrical surface of the outer peripheral portion of the outer member 11 are non-heat treated surfaces, and cold forging. Keep the surface. In addition, the inboard side end of the outer member 11 can be formed by rolling forging from the finished shape of the cold hermetic forging, so that a large diameter portion can be formed without adding surplus, contributing to weight reduction. can do.

  On the other hand, the shaft portion 16 of the inner member 12 is made of a ring-shaped billet made of carbon steel for mechanical structure that has been spheroidized and annealed, formed by a cold sealed forging method, and used without annealing after forging. Good. Further, by forming the knuckle mounting flange 17 by side extrusion, the hardness of the flange root portion can be increased and the strength is also improved. Since the end portion on the outboard side of the shaft portion 16 is not greatly deformed, the hardness is close to that of the billet. Therefore, it is convenient for both the caulking of the inner ring 19 and the thread cutting for screw fastening.

  In addition, since the cold hermetic forging can obtain a very accurate shape, the inboard-side end surface of the shaft portion 16 can obtain a highly accurate plane unless annealing is performed after forging. For this reason, the inboard side end surface of the shaft portion 16 can be used as a reference surface for grinding the inner ring raceway surface 12a on the inboard side without machining. Of course, the surface of the shaft portion 16 needs to be subjected to high-frequency heat treatment (quenching and tempering by an electromagnetic induction method) from the inner ring raceway surface 12a on the inboard side to the small diameter step portion 18 in order to obtain strength. The reference surface (position to which the shoe is applied) in the radial direction of grinding of the inner ring raceway surface 12a on the board side needs to be a position to be ground (so-called groove shoe).

  As described above, according to the hub unit bearing 10 of the present embodiment, the pitch circle diameter (PCD) of the 13 rows of balls on the inboard side is larger than the pitch circle diameter of the 13 rows of balls on the outboard side. The pilot diameter of the flange 14 can be reduced, and the weight of the bearing 10 can be reduced. In addition, since a separate member for fixing the inner ring 19 to the shaft portion 16 is not required, the bearing structure can be simplified, and the weight and cost of the bearing 10 can be reduced. In addition, since the load capacity of the 13 rows of balls on the inboard side can be increased, the bearing life can be improved. Further, the weight reduction of the bearing 10 can save energy and resources, reduce the unsprung weight, and improve the driving stability of the automobile.

  As a modification of the present embodiment, as shown in FIG. 2, the knuckle mounting flange 17 of the inner member 12 may be extended radially outward and bent to the outboard side to be molded. . In this case, the distance between the hub flange 14 and the knuckle mounting flange 17 can be shortened.

(Second Embodiment)
Next, a hub unit bearing according to a second embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a cross-sectional view of an essential part for explaining a second embodiment of the hub unit bearing according to the present invention.

  As shown in FIG. 3, the hub unit bearing 20 of the present embodiment is for an outer ring rotating type driven wheel, and has an outer ring raceway surface 21 a, 21 a on the inner peripheral surface, and the outer side constituting the rotating wheel. Rolling in the circumferential direction between the member 21, a pair of inner members 31, 32 that are disposed adjacent to each other in the axial direction and have the inner ring raceway surface 22 on the outer circumferential surface, and the outer ring raceway surface 21a and the inner ring raceway surface 22. And a ball 23 that can be arranged.

  The outer member 21 is a cylindrical member, and has a hub flange 24 that extends radially outward at an end portion on the outboard side (left end portion in FIG. 1) of the outer peripheral surface thereof. On the hub flange 24, a plurality of hub bolts 25 for mounting wheels (not shown), brake rotors, and the like that constitute wheels on the outboard side end surface are implanted at substantially equal intervals in the circumferential direction.

  The hub unit bearing 20 is fixed to the fixed shaft 26 by fitting the pair of inner members 31 and 32 to the outer peripheral surface of the fixed shaft 26 and crimping the end portion on the outboard side of the fixed shaft 26. Further, a knuckle mounting flange 27 extending radially outward is formed at an inboard side end portion (right end portion in FIG. 1) of the outer peripheral surface of the fixed shaft 26. In this embodiment, the pair of inner members 31 and 32 are fixed to the fixed shaft 26 by caulking, but instead, the pair of inner members 31 and 32 are fixed to the fixed shaft 26 by screw fastening. May be.

  In this embodiment, the outer ring raceway surface 21a on the inboard side of the outer member 21 is formed to have a larger diameter than the outer ring raceway surface 21a on the outboard side, and the inner ring raceway surface 22 of the inner member 32 on the inboard side is out. The inner ring raceway surface 22 of the board-side inner member 31 is formed to have a larger diameter, and the pitch circle diameter (PCD) of the 23 rows of balls on the inboard side is larger than the pitch circle diameter of the 23 rows of balls on the outboard side. .

  Here, the outer member 21 is made of an annular billet made of carbon steel for mechanical structure that has been spheroidized and annealed, and the outer peripheral surface and the inner peripheral surface are formed by cold hermetic forging. The hub flange 24 may be formed at The hub flange 24 is preferably a so-called star flange in which a plurality of flange pieces are arranged in the circumferential direction of the outer member 21. In addition, a cylindrical surface for applying a shoe when the outer ring raceway surface 21a is ground is formed on the outer peripheral portion of the outer member 21.

  Further, since the end face of the hub flange 24 is an accurate flat surface, it may be used as a reference surface for grinding the outer ring raceway surface 21a together with the shoe without annealing after forging and without machining. The outer ring raceway surface 21a needs to be induction hardened (quenching and tempering using an electromagnetic induction method), but the end surface of the hub flange 24 and the cylindrical surface of the outer peripheral portion of the outer member 21 are non-heat treated surfaces, and cold forging. Keep the surface. In addition, the inboard side end of the outer member 21 can be formed by rolling forging from the finished shape of the cold hermetic forging, so that a large diameter portion can be formed without adding surplus, contributing to weight reduction. can do.

  As described above, according to the hub unit bearing 20 of the present embodiment, the pitch circle diameter (PCD) of the 23 rows of balls on the inboard side is larger than the pitch circle diameter of the 23 rows of balls on the outboard side. The pilot diameter of the flange 24 can be reduced, and the weight of the bearing 20 can be reduced. In addition, since a separate member for fixing the pair of inner members 31 and 32 to the fixed shaft 26 is not required, the bearing structure can be simplified, and the weight and cost of the bearing 20 can be reduced. Moreover, since the load capacity of the 23 rows of balls on the inboard side can be increased, the bearing life can be improved. Further, the weight reduction of the bearing 20 can save energy and resources, reduce the unsprung weight, and improve the driving stability of the automobile.

It is principal part sectional drawing for demonstrating 1st Embodiment of the hub unit bearing which concerns on this invention. It is principal part sectional drawing for demonstrating the modification of the hub unit bearing of 1st Embodiment. It is principal part sectional drawing for demonstrating 2nd Embodiment of the hub unit bearing which concerns on this invention.

Explanation of symbols

10, 20 Hub unit bearing 11, 21 Outer member 11a, 21a Outer ring raceway surface 12, 31, 32 Inner member 12a, 22 Inner ring raceway surface 13, 23 Ball (rolling element)
14, 24 Hub flange 15, 25 Hub bolt 16 Shaft portion 17, 27 Knuckle mounting flange 18 Small diameter step portion 19 Inner ring 26 Fixed shaft

Claims (8)

A cylindrical outer member which has a double row outer ring raceway surface on the inner peripheral surface and a hub flange at the outer end in the vehicle width direction and forms a rotating wheel, and an axially adjacent outer member A hub unit bearing comprising: a pair of inner members having inner ring raceway surfaces on surfaces; and rolling elements arranged to be capable of rolling in a circumferential direction between the outer ring raceway surface and the inner ring raceway surface. ,
A hub unit bearing characterized in that a pitch circle diameter of a rolling element row on the inner side in the vehicle width direction is larger than a pitch circle diameter of a rolling element row on the outer side in the vehicle width direction. A cylindrical outer member that has a double-row outer ring raceway surface on the inner peripheral surface and a hub flange at the outer end in the vehicle width direction to form a rotating wheel, and a double-row inner ring raceway surface on the outer peripheral surface And an inner member having a knuckle mounting flange at the inner end in the vehicle width direction, and a rolling element disposed so as to be able to roll in a circumferential direction between the outer ring raceway surface and the inner ring raceway surface, With
The inner member is fitted to a shaft portion on which the inner ring raceway surface on the inner side in the vehicle width direction is formed, the knuckle mounting flange is formed, and an end portion on the outer side in the vehicle width direction of the shaft portion, A hub unit bearing having an inner ring on which the inner ring raceway surface on the outer side in the vehicle width direction is formed,
A hub unit bearing characterized in that a pitch circle diameter of a rolling element row on the inner side in the vehicle width direction is larger than a pitch circle diameter of a rolling element row on the outer side in the vehicle width direction. The inner ring is fixed by caulking to the shaft portion,
The shaft portion is made of a spheroidized annealed carbon steel billet for mechanical structure, formed by cold hermetic forging, and the root portion of the knuckle mounting flange is crimped without annealing after the forging. The hub unit bearing according to claim 2, wherein the hub unit bearing is incorporated in a harder state than a front shaft end portion.   The shaft portion is made of an annular billet made of carbon steel for mechanical structure that has been subjected to spheroidizing annealing, formed by cold hermetic forging, and the flange for knuckle mounting is formed by a side extrusion method, The hub unit bearing according to claim 2, wherein at least the flange surface is not machined.   The shaft portion is quenched and tempered by electromagnetic induction without machining after cold hermetic forging, and the outer ring surface, which is a non-heat treated surface on the cold forged surface, is supported by a shoe, and the inner ring raceway surface is ground. The hub unit bearing according to claim 3 or 4, wherein the hub unit bearing is provided.   The outer member is made of an annular billet made of carbon steel for mechanical structure that has been subjected to spheroidizing annealing. The outer peripheral surface and the inner peripheral surface are formed by cold hermetic forging, and the hub is formed by lateral extrusion. The hub unit bearing according to any one of claims 1 to 5, wherein a flange is formed, and at least an outer peripheral surface and the flange surface are not machined.   The outer member is ground and tempered by electromagnetic induction without machining the outer ring raceway surface after cold hermetic forging, and the outer peripheral portion which is a non-heat treated surface is cold-forged and ground with a shoe. The hub unit bearing according to claim 6.   The hub unit bearing according to any one of claims 1 to 7, wherein the outer member is formed by expanding an inner end in a vehicle width direction from a forged finished shape.

Images