JP2020060231A - Hub unit bearing for drive wheels - Google Patents

Abstract

To provide a hub unit bearing for a drive wheel capable of securing a necessary hardened layer thickness even at a root part of a knuckle flange, so that a bearing life can be improved.SOLUTION: Hardened layers 11e, 11f are formed on two rows of outer ring raceway surfaces 11a, 11b of an outer ring member 11 of a hub unit bearing 10, a knuckle flange 20 is formed on an outer diameter surface of the outer ring member 11, a thinned portion 21 on which the outer diameter surface of the outer ring member 11 is a convex surface, is formed on a root part of the knuckle flange 20 of the outer ring member 11, and the thinned portion 21 is formed in a manner that a line Cb indicating an inboard-side contact angle passes therethrough.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hub unit bearing for a drive wheel, and more particularly to a hub unit bearing that rotatably supports a front wheel in a front-wheel drive vehicle in which the front wheel has the functions of both the drive wheel and the steered wheel.

  The hub unit bearing rotatably supports a vehicle wheel and a braking rotary member with respect to the suspension device. As a conventional drive wheel hub unit bearing, an outer ring member having a double row outer ring raceway surface on an inner diameter surface, a hub having a double row inner ring raceway surface on an outer diameter surface, each outer ring raceway surface and each inner ring raceway surface A plurality of balls arranged in each row between, and a knuckle flange attached to the knuckle is formed on the outer diameter surface of the outer ring member, and on the outer diameter surface of the outboard side end of the hub, It is known that a hub flange to which tire wheels and the like are attached is formed (see, for example, Patent Documents 1 and 2). Further, in Patent Document 1, a hardened layer that has been subjected to high-frequency heat treatment in order to satisfy rolling fatigue life is formed on a portion of each outer ring raceway surface on the inner diameter surface of the outer ring member. Further, Patent Document 2 describes that a recessed groove-shaped relief recess is formed over the entire circumference in the circumferential direction on the inboard side of the root of the knuckle flange. The outboard side is the direction toward the outside of the vehicle body of the automobile when the hub unit bearing is mounted on the automobile, and is the left side of FIG. The opposite side is the inboard side, which is the right side of FIG.

  In particular, in a front wheel hub unit bearing of a front wheel drive vehicle, a drive shaft of a CVJ (constant velocity joint) and a steering mechanism of a steering knuckle are connected and fixed in order to serve as a drive wheel and a steering wheel. In order to bring the kingpin angle close to the swing center of the constant velocity joint, it is necessary to reduce the axial dimension of the hub unit bearing. Therefore, it is necessary to reduce the distance between the rows of balls and to shorten the distance between the knuckle flange and the hub flange, and the knuckle flange is often arranged between the rows of the outer ring members.

JP, 2003-156054, A JP, 2017-137884, A

  By the way, in the case of a hub unit bearing having such a structure, a portion (knuckle pilot) fitted to the inboard side end portion of the outer diameter surface of the outer ring member (knuckle pilot) overlaps with the outer ring raceway surface on the inboard side in the radial direction. Since it is formed to be long, the groove bottom portion of the outer ring raceway surface on the inboard side of the outer ring member becomes thin. Also, in hub unit bearings, there is a difference in the load between the inboard side raceway surface and the outboard side raceway surface (there is a difference in life between the inboard side raceway surface and the outboard side raceway surface), so the raceway on the heavy load side We would like to improve the durability by making the hardened layer on the surface thicker than the raceway surface on the side where the load is light. Normally, the load on the inboard side raceway surface is often larger than the load on the outboard side raceway surface.However, as mentioned above, the groove bottom of the outer ring raceway surface on the inboard side becomes thin, so When the hardened layer is formed by high-frequency heat treatment, it is possible that the hardened layer at the groove bottom part penetrates to the outer diameter surface of the outer ring member, or the non-hardened portion becomes thin and cracks occur on the outer diameter surface of the outer ring member.

  Therefore, when the output of the high frequency heat treatment is reduced in order to prevent the above-mentioned penetration of the hardened layer and the occurrence of outer diameter surface cracks, the contact angle direction portion where the heat capacity of the outer ring member is large (the portion where the outer ring member has a large radial thickness). ), The hardened layer becomes thin, especially at the root of the knuckle flange, which has a large heat capacity.Therefore, there are some areas where the required hardened layer thickness cannot be obtained. Direction and the axial direction of the raceway surface become uneven, which may affect the bearing life.

  The present invention has been made in view of the above-mentioned problems, and an object thereof is to secure a necessary thickness of a hardened layer even at a root portion of a knuckle flange, thereby improving a bearing life. (EN) Provided is a hub unit bearing for a drive wheel.

The above object of the present invention is achieved by the following configurations.
(1) An outer ring member having two rows of outer ring raceway surfaces formed on the inner diameter surface, a hub having two rows of inner ring raceway surfaces formed on the outer diameter surface, the two rows of outer ring raceway surfaces, and the two rows of inner rings A hub unit bearing for a drive wheel, comprising a plurality of balls rotatably arranged in two rows with respect to a raceway surface and provided in a state in which a rear surface combination type contact angle is provided, the outer ring member A hardened layer is formed on the outer ring raceway surfaces of the two rows, a knuckle flange attached to a knuckle is formed on the outer diameter surface of the outer ring member, and a line indicating the contact angle passes through the outer diameter surface of the outer ring member. On the side of the outer ring member, a root portion of the knuckle flange of the outer ring member is provided with a meat steal portion in which the outer diameter surface of the outer ring member is a convex curved surface, and the meat steal portion passes through a line indicating the contact angle. Hub unit for drive wheels characterized in that Tsu door bearing.
(2) The thickness of the outer ring member in the direction of the contact angle is substantially the same as the thickness of the outer ring raceway surface in the direction of the groove bottom due to the thickness-thickened portion. Drive wheel hub unit bearing.
(3) In (1) or (2), the thickness of the hardened layer in the contact angle direction is substantially the same as the thickness of the hardened layer in the groove bottom direction of the outer ring raceway surface. Hub unit bearing for drive wheel described.

  According to the present invention, the hardened layer is formed on the outer ring raceway surfaces of the two rows of the outer ring member, the knuckle flange attached to the knuckle is formed on the outer diameter surface of the outer ring member, and any of the root portions of the knuckle flange of the outer ring member is formed. On the (inboard side or outboard side), a meat stealing portion in which the outer diameter surface of the outer ring member is a convex curved surface is provided, and the meat stealing portion is formed so that the line indicating the contact angle passes therethrough. The wall thickness of the outer ring member in the contact angle direction is substantially the same as the wall thickness of the outer ring raceway surface in the groove bottom direction over the entire circumference. As a result, the heat capacity in the direction of the contact angle of the outer ring raceway (the heat capacity of the root portion of the knuckle flange) can be reduced, so that the heat capacity of the outer ring member can be made substantially uniform over the entire axial direction. Therefore, the thickness of the hardened layer in the direction of the contact angle is approximately the same as the thickness of the hardened layer in the direction of the groove bottom of the outer ring raceway surface, and the thickness of the hardened layer is set in the circumferential direction of the entire raceway surface and the axis of the raceway surface. It can be made substantially even in the direction. Therefore, it is possible to secure a necessary thickness of the hardened layer even at the root portion of the knuckle flange on the raceway surface side where the load is large, and thus it is possible to improve the bearing life.

It is a sectional view explaining a 1st embodiment of the hub unit bearing for drive wheels concerning the present invention. It is sectional drawing explaining 2nd Embodiment of the hub unit bearing for drive wheels which concerns on this invention.

  Hereinafter, embodiments of the drive wheel 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, a first embodiment of a drive wheel hub unit bearing according to the present invention will be described. Incidentally, in the present embodiment, in the case of making the wall thickness in the contact angle direction of the outer ring raceway surface and the wall thickness in the groove bottom direction substantially the same over the entire circumference of the hardened layer of the outer ring raceway surface on the inboard side. It is an embodiment.

  As shown in FIG. 1, a drive wheel hub unit bearing (hereinafter, also referred to as “hub unit bearing”) 10 of the present embodiment includes an outer ring member 11, a hub wheel 12 that constitutes a hub, and a hub together with the hub wheel 12. And a plurality of inner rings 13 that are integrally fixed to the hub wheel 12 and are arranged in two rows so as to be rollable between the inner diameter surface of the outer ring member 11 and the outer diameter surfaces of the hub wheel 12 and the inner ring 13. Inner space between the outer ring member 11 and the hub (hub ring 12, inner ring 13), a pair of cages 15 that respectively retain the two rows of balls 14 at equal intervals in the circumferential direction. A seal 16a for closing the outboard side of 10a and a seal 16b for closing the inboard side of the bearing internal space 10a are provided.

  Two rows of outer ring raceway surfaces 11a and 11b are formed on the inner diameter surface of the outer ring member 11 so as to be axially separated from each other. Inner ring raceway surfaces 12a and 13a are formed on the outer diameter surfaces of the hub wheel 12 and the inner ring 13 respectively corresponding to the outer ring raceway surfaces 11a and 11b of the outer ring member 11. A plurality of balls 14 rotatably held by a cage 15 are arranged at equal intervals in the circumferential direction on the two rows of raceways formed by the outer raceway surfaces 11a and 11b and the inner raceway surfaces 12a and 13a. Has been done. As a result, the hub wheel 12 and the inner wheel 13 can rotate with respect to the outer wheel member 11.

  A knuckle flange 20 attached to a knuckle on the vehicle body side is formed on the outer diameter surface of the outer ring member 11 so as to extend radially outward. Then, the knuckle flange 20 of the present embodiment is located between the two rows of the outer ring raceway surfaces 11a and 11b of the outer ring member 11 on the outer ring raceway surface 11a side on the outboard side in a state of radially overlapping with the outer ring raceway surface 11a ( The outer ring raceway surface 11a is arranged radially outside). Therefore, a line Cb indicating the contact angle on the inboard side, which will be described later, passes through the outer diameter surface of the outer ring member 11. A plurality of knuckle flanges 20 are formed on the outer diameter surface of the outer ring member 11 at substantially equal intervals or unequal intervals in the circumferential direction.

  The outer ring member 11 is made of carbon steel, and the two rows of the outer ring raceway surfaces 11a and 11b of the outer ring member 11 are formed with hardened layers 11e and 11f by heat treatment all around. The hardened layers 11e and 11f are formed by high frequency heat treatment in which the two rows of outer ring raceway surfaces 11a and 11b are simultaneously heated by the high frequency heating coil. Therefore, the portions of the outer ring member 11 other than the hardened layers 11e and 11f are non-hardened portions that have not been heat-treated.

  The plurality of balls 14 are in contact with the outer ring raceway surfaces 11a and 11b and the inner ring raceway surfaces 12a and 13a in a state in which a back surface combination type (DB type) contact angle is provided. 1 is a line that passes through the groove bottom 11c of the outer ring raceway surface 11a on the outboard side and indicates a contact angle of 0 ° on the outboard side, and reference symbol Lb is the outer ring raceway surface on the inboard side. A line passing through the groove bottom 11d of 11b and showing a contact angle of 0 ° on the inboard side, a reference sign Ca is a line showing a contact angle on the outboard side, and a reference sign Cb is a contact angle on the inboard side. It is a line.

  A small diameter step portion 12b is formed on the outer diameter surface of the end portion of the hub wheel 12 on the inboard side, and the inner ring 13 is fitted onto the small diameter step portion 12b. A spline hole 12c is formed in the center of the hub wheel 12 so as to pass through the drive shaft of a constant velocity joint (not shown) so as to penetrate therethrough in the axial direction. Then, by holding the outboard side surface of the hub wheel 12 and the inboard side end surface of the inner ring 13 by a constant velocity joint in which the drive shaft is inserted through the spline hole 12c and a fastening member (nut or the like) not shown, A proper preload is applied to the plurality of balls 14 in two rows.

  Further, a hub flange 12d for mounting a tire wheel (not shown) or the like is formed on the outer diameter surface of the end portion on the outboard side of the hub wheel 12 so as to extend radially outward. The hub flange 12d is provided with a plurality of hub bolts 12e for fastening a tire wheel or the like (not shown) at equal intervals in the circumferential direction. The hub flange 12d is formed on the outer diameter surface of the hub wheel 12 over the entire circumference.

  Further, in the present embodiment, at the root portion of the side surface of the knuckle flange 20 of the outer ring member 11 on the inboard side, a meat-thief portion 21 in which the outer diameter surface of the outer ring member 11 is a convex curved surface is provided. The meat stealing portion 21 is formed so that the line Cb indicating the contact angle on the inboard side passes through. The meat-thief portion 21 is formed on the outer diameter surface of the outer ring member 11 over the entire circumference. For example, in the present embodiment, the meat-thief portion 21 is formed so that the line Cb indicating the contact angle from the inboard side of the knuckle flange 20 to the inboard side is crossed to the inboard side, and the knuckle mounting surface is machined. It also serves as an escape groove. Further, the shape of the convex curved surface around the line Cb indicating the contact angle on the inboard side is concentric with the outer ring raceway surface 11b having a circular cross section, and is formed in an arc shape having a larger radius of curvature than the outer ring raceway surface 11b. ing. However, it may be configured by a curved surface other than the arc shape, or may be configured arbitrarily such as a combination of a plurality of curved surfaces.

  Further, in the meat-thief portion 21, the wall thickness in the direction of the line Cb indicating the contact angle of the outer ring member 11 on the inboard side is the same as the wall thickness in the direction of the groove bottom 11d of the outer ring raceway surface 11b (in the direction of the alternate long and short dash line Lb). It is formed so as to be substantially the same. As a result, the heat capacity (heat capacity of the root portion of the knuckle flange 20) in the direction of the line Cb indicating the contact angle of the outer ring member 11 on the inboard side is reduced. Therefore, since the heat capacity of the portion of the outer ring member 11 on the inboard side of the knuckle flange 20 is substantially uniform over the entire axial direction, the thickness in the direction of the line Cb indicating the contact angle of the hardened layer 11f is the hardened layer 11f. The thickness is substantially the same as the thickness of the outer ring raceway surface 11b in the direction of the groove bottom 11d. That is, even if the output of the high frequency heat treatment is reduced in order to prevent the above-mentioned penetration of the hardened layer and the occurrence of outer diameter surface cracks, the heat capacity of the inboard side portion of the outer ring member 11 relative to the knuckle flange 20 is the entire axial direction. The thickness of the hardened layer 11f can be made substantially uniform in the circumferential direction of the entire raceway surface and in the axial direction of the raceway surface because the thickness of the hardened layer 11f is substantially uniform.

  As described above, according to the hub unit bearing 10 of the present embodiment, at the root portion of the side surface of the knuckle flange 20 of the outer ring member 11 on the inboard side, the outer diameter surface of the outer ring member 11 has a convex curved surface. 21 is provided, and the meat stealing portion 21 is formed so that the line Cb indicating the contact angle on the inboard side passes therethrough. Therefore, the meat in the direction of the line Cb indicating the contact angle of the outer ring raceway surface 11b on the inboard side is formed. The thickness is substantially the same as the thickness of the outer ring raceway surface 11b in the direction of the groove bottom 11d over the entire circumference. As a result, the heat capacity (heat capacity of the root portion of the knuckle flange 20) in the direction of the line Cb indicating the contact angle of the outer ring member 11 on the inboard side can be made smaller, so that the inboard member than the knuckle flange 20 of the outer ring member 11 can be made smaller. The heat capacity of the side portion can be made substantially uniform over the entire axial direction. Therefore, the thickness of the hardened layer 11f in the direction of the line Cb indicating the contact angle is substantially the same as the thickness of the hardened layer 11f in the direction of the groove bottom 11d of the outer ring raceway surface 11b, and the thickness of the hardened layer 11f is set to the raceway surface. It can be made substantially uniform in the entire circumferential direction and the axial direction of the raceway surface. Therefore, the necessary thickness of the hardened layer 11f can be ensured even at the root portion of the side surface of the knuckle flange 20 on the inboard side, and thus the bearing life can be improved.

  As the first embodiment, in the hub unit bearing 10 shown in FIG. 1, the pitch circle diameter (PCD) of the outboard side ball row is set to be larger than the pitch circle diameter of the inboard side ball row. , A different diameter PCD hub unit bearing. In the hub unit bearing 10 having such a structure, most of the moment load is supported by the row of balls on the outboard side, so that the moment rigidity of the hub unit bearing 10 is increased. For this reason, a large rolling element load is applied near the groove shoulder of the outer ring raceway 11a on the outboard side (on the inboard side, which is the inner side in the radial direction), but in the case of this embodiment, the meat-thief portion 21 is out. Since the hardened layer 11e formed in the vicinity of the groove shoulder of the outer ring raceway surface 11a on the board side is also in close proximity, even in the vicinity of the groove shoulder of the outer ring raceway surface 11a on the outboard side, the heat capacity change due to the knuckle flange 20 is reduced and the hardening is performed. The effect of making the thickness of the layer 11e thick and uniform over the entire circumference is also obtained.

(Second embodiment)
Next, with reference to FIG. 2, a second embodiment of the drive wheel hub unit bearing according to the present invention will be described. In addition, about the same or equivalent part as the said 1st Embodiment, the same code | symbol is attached | subjected to drawing and the description is abbreviate | omitted or simplified. Further, in the present embodiment, in the case where the wall thickness in the contact angle direction of the outer ring raceway surface and the wall thickness in the groove bottom direction are made substantially the same over the entire circumference of the hardened layer of the outer ring raceway surface on the outboard side. It is an embodiment.

  In the hub unit bearing 10B of the present embodiment, as shown in FIG. 2, the knuckle flange 20 is arranged between the two rows of the outer ring raceway surfaces 11a and 11b of the outer ring member 11 on the inboard side outer ring raceway surface 11b side. It That is, the line Ca indicating the contact angle on the outboard side passes through the outer diameter surface of the outer ring member 11 located on the outboard side of the knuckle flange 20. Further, at the root portion of the side surface of the knuckle flange 20 of the outer ring member 11 on the outboard side, a meat-thief portion 21 in which the outer diameter surface of the outer ring member 11 is a convex curved surface is provided. The meat stealing portion 21 is formed so that the line Ca indicating the contact angle on the outboard side passes through. For example, in the present embodiment, the meat stealing portion 21 is formed so that the line Ca indicating the contact angle from the outboard side of the knuckle flange 20 to the outboard side is crossed to the outboard side.

  As described above, according to the hub unit bearing 10B of the present embodiment, at the root portion of the side surface of the knuckle flange 20 of the outer ring member 11 on the outboard side, the outer peripheral surface of the outer ring member 11 has a convex curved surface. 21 is provided, and the meat stealing portion 21 is formed so that the line Ca indicating the contact angle on the outboard side passes therethrough. Therefore, the meat in the direction of the line Ca indicating the contact angle of the outer ring raceway surface 11a on the outboard side is formed. The thickness is substantially the same as the thickness of the outer ring raceway surface 11a in the direction of the groove bottom 11c over the entire circumference. As a result, the heat capacity in the direction of the line Ca indicating the contact angle of the outer ring member 11 on the outboard side (the heat capacity of the root portion of the knuckle flange 20) can be made smaller, so that the outboard than the knuckle flange 20 of the outer ring member 11 can be outboarded. The heat capacity of the side portion can be made substantially uniform over the entire axial direction. Therefore, the thickness of the hardened layer 11e in the direction of the line Ca indicating the contact angle becomes approximately the same as the thickness of the hardened layer 11e in the direction of the groove bottom 11c of the outer ring raceway surface 11a, and the thickness of the hardened layer 11e is set to the raceway surface. It can be made substantially uniform in the entire circumferential direction and the axial direction of the raceway surface. Therefore, the required thickness of the hardened layer 11e can be ensured even at the root portion of the side surface of the knuckle flange 20 on the outboard side, and thus the bearing life can be improved.

As the second embodiment, in the hub unit bearing 10B shown in FIG. 2, the pitch circle diameter (PCD) of the ball row on the outboard side is set to be the same as the pitch circle diameter of the ball row on the inboard side. It is a hub unit bearing. In the hub unit bearing 10B having such a structure, since the meat-thief portion 21 is also close to the hardened layer 11f formed in the direction of the line Cb indicating the contact angle of the outer ring raceway surface 11b on the inboard side, the outer ring on the inboard side is formed. Even in the vicinity of the line Cb indicating the contact angle of the raceway surface 11b, the change in heat capacity due to the knuckle flange 20 is reduced, and the thickness of the hardened layer 11f in the vicinity of the direction of the line Cb indicating the contact angle on the inboard side is set to the entire circumference. The effect of making it thicker and more uniform is obtained.
Other configurations and operational effects are the same as those in the first embodiment.

  It should be noted that the present invention is not limited to the examples illustrated in the above embodiments, and can be appropriately changed without departing from the scope of the present invention.

10, 10B Hub unit bearing for drive wheel 10a Bearing internal space 11 Outer ring member 11a, 11b Outer ring raceway surface 11c, 11d Groove bottom 11e, 11f Hardened layer 12 Hub ring 12a Inner ring raceway surface 12b Small diameter stepped portion 12c Spline hole 12d Hub flange 12e Hub bolt 13 Inner ring 13a Inner ring raceway surface 14 Ball 15 Retainer 16a, 16b Seal 20 Knuckle flange 21 Meat steal La La Line showing 0 ° contact angle on outboard side Lb Line showing 0 ° contact angle on inboard side Ca outboard Line showing the contact angle on the side Cb Line showing the contact angle on the inboard side

Claims (3)

An outer ring member having two rows of outer ring raceway surfaces formed on the inner diameter surface,
A hub having two rows of inner ring raceways formed on the outer diameter surface,
A plurality of balls arranged in a rollable manner in two rows between the two rows of outer ring raceways and the two rows of inner ring raceways and provided in a state in which a rear surface combination type contact angle is provided. A hub unit bearing for drive wheels,
A hardened layer is formed on the outer ring raceways of the two rows of the outer ring member,
A knuckle flange attached to a knuckle is formed on the outer diameter surface of the outer ring member,
On the side where the line indicating the contact angle passes through the outer diameter surface of the outer ring member, a root portion of the knuckle flange of the outer ring member is provided with a meat-thickened portion in which the outer diameter surface of the outer ring member is a convex curved surface. The
The hub unit bearing for a drive wheel, wherein the meat-thief portion is formed so that a line indicating the contact angle passes therethrough.   The drive wheel according to claim 1, wherein the thickness of the outer ring member in the direction of the contact angle is substantially the same as the thickness of the outer ring member in the direction of the groove bottom of the outer ring raceway surface due to the recessed portion. Hub unit bearing for.   3. The drive wheel according to claim 1, wherein a thickness of the hardened layer in a direction of the contact angle is substantially the same as a thickness of the hardened layer in a direction of a groove bottom of the outer ring raceway surface. Hub unit bearing.

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