WO2025022681A1 - Bearing device for drive wheel - Google Patents

Abstract

This bearing device (1) for a drive wheel comprises: an outer ring (10) that is fixed to a vehicle body-side member (2); a hub (20) to which a wheel (3) is attached; and an outer joint member (30) that has a bottomed cylindrical part (31) and a connection part (35) that is connected to the hub (20) so as to be able to transmit torque. In the outer joint member (30), a first inner raceway surface (33) provided on the outer surface of the cylindrical part (31) is disposed outside in the radial direction (Y) of an outer guide groove (32) provided to the inner surface of the cylindrical part (31), so as to overlap at least a portion of the outer guide groove (32).

Description

Bearing device for driving wheels

This disclosure relates to a bearing device for a drive wheel.

Patent Document 1 below discloses a conventional bearing device for a driving wheel. This bearing device for a driving wheel is a rolling bearing device for rotatably supporting a driving wheel, and has a structure in which a rolling bearing and a constant velocity universal joint are integrated. The rolling bearing is composed of an outer ring, a hub wheel equivalent to an inner ring, a drive shaft with which the inner ring is integrated, and rolling elements, etc., while the constant velocity universal joint is composed of a drive shaft with which an outer coupling member is integrated, an inner coupling member, balls, etc.

JP 2009-292275 A

In vehicles powered by electric motors or internal combustion engines, there is a demand for extending the driving range and improving electricity consumption or fuel economy. For this reason, it is desirable to reduce the weight of the bearing device for the drive wheel. The bearing device for the drive wheel in Reference 1 has a structure in which the inner ring is eliminated by providing an inner ring raceway surface on the outer joint member of the constant velocity joint of the drive shaft, which is effective in reducing weight, but further weight reduction is desired in the design of this type of bearing device for the drive wheel.

This disclosure was made in consideration of these issues, and aims to provide a technology that is effective in reducing the weight of bearing devices for drive wheels.

One aspect of the present disclosure is
An outer ring fixed to a vehicle body side member;
a hub to which the wheel is attached;
an outer joint member having a bottomed cylindrical portion and a connecting portion that is connected to the hub so as to be capable of transmitting torque;
an inner joint member received in the cylindrical portion of the outer joint member;
a plurality of first rolling elements provided between the outer ring and the outer joint member and supporting the outer ring and the outer joint member so as to be rotatable relative to each other in a direction around an axis;
a plurality of second rolling elements provided between the outer ring and the hub and supporting the outer ring and the hub so as to be capable of relative rotation in a direction around the axis;
a plurality of third rolling elements that connect the cylindrical portion of the outer joint member and the inner joint member in a torque transmittable manner;
Equipped with
an outer guide groove that guides the third rolling elements along an axial direction is provided on an inner surface of the cylindrical portion of the outer joint member in a radial direction;
a first inner raceway surface that guides the first rolling elements in a circumferential direction is provided on a radial outer surface of the cylindrical portion of the outer joint member,
a bearing device for a driving wheel, in which, in the outer joint member, the first inner raceway surface is disposed radially outside the outer guide groove so as to overlap at least a portion of the outer guide groove, or the first inner raceway surface is disposed on a vertical line perpendicular to a tangent to the outer guide groove;
is located.

In the driving wheel bearing device of the above aspect, a first inner raceway surface that guides the multiple first rolling elements in the circumferential direction is provided on the radial outer surface of the cylindrical portion of the outer joint member, and an outer guide groove that guides the multiple third rolling elements along the axial direction is provided on the radial inner surface of the cylindrical portion of the outer joint member. With a structure in which the first rolling elements are in direct contact with the cylindrical portion of the outer joint member, no separate member is interposed between the first rolling elements and the outer joint member, making it possible to reduce weight accordingly.

In addition, in the outer joint member, the first inner raceway surface is arranged radially outward of the outer guide groove so as to overlap at least a portion of the outer guide groove. Alternatively, in the outer joint member, the first inner raceway surface is arranged on a vertical line perpendicular to the tangent line of the outer guide groove. This allows the outer guide groove and the first inner raceway surface to be brought closer together in the axial direction. In this case, the axial dimension of the connecting portion of the outer joint member can be shortened, making it possible to further reduce the weight of the driving wheel bearing device.

The above-mentioned aspect allows the weight of the driving wheel bearing device to be reduced.

Note that the reference characters in parentheses in the claims indicate the corresponding relationship to the specific means described in the embodiments described below, and do not limit the technical scope of this disclosure.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is an axial cross-sectional view of a driving wheel bearing device according to a first embodiment; FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1; FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1; FIG. 4 is a cross-sectional view showing a contact state between an outer guide groove provided on an inner surface of a cylindrical portion of an outer joint member shown in FIG. 1 and a first ball; FIG. 5 is a partial cross-sectional view for explaining a first weight-saving structure of the driving wheel bearing device of the first embodiment; FIG. 6 is a partial cross-sectional view for explaining a second weight-saving structure of the driving wheel bearing device of the first embodiment; FIG. 7 is a partial cross-sectional view for explaining a third weight-saving structure and a fourth weight-saving structure of the driving wheel bearing device of the first embodiment; FIG. 8 is a partial cross-sectional view for explaining a fifth weight-saving structure of the driving wheel bearing device of the first embodiment; FIG. 9 is a partial cross-sectional view for explaining a sixth weight-saving structure and a seventh weight-saving structure of the driving wheel bearing device of the first embodiment; FIG. 10 is an axial cross-sectional view illustrating an eighth weight-saving structure of the driving wheel bearing device according to the first embodiment when the vehicle moves straight ahead; FIG. 11 is an enlarged cross-sectional view of a portion of FIG. 10; FIG. 12 is an axial cross-sectional view illustrating an eighth weight-saving structure of the driving wheel bearing device according to the first embodiment when turning left; FIG. 13 is an enlarged cross-sectional view of a portion of FIG. 12; FIG. 14 is a cross-sectional view showing a part of a circumferential cross section of a cylindrical portion of an outer joint member in FIG. 11 or FIG. 13 ; 15 is a cross-sectional view showing a part of a circumferential cross section of the cylindrical portion of the outer joint member in FIG. 13. FIG.

Below, one embodiment of the above aspect will be described with reference to the drawings.

In the drawings used to explain this embodiment, unless otherwise specified, the axial direction of the drive wheel bearing device and its components is the X direction, the radial direction is the Y direction, the circumferential direction is the Z direction, and the direction around the axis is the D direction.

(Embodiment 1)
1, the driving wheel bearing device 1 of the first embodiment (hereinafter simply referred to as the "bearing device") has a structure in which a constant velocity universal joint 1a and a rolling bearing 1b are integrated. This bearing device 1 is mounted on a vehicle driven by an electric motor or an internal combustion engine, and transmits torque generated by the drive source to the wheel 3 and supports the wheel 3 for rotation.

The constant velocity universal joint 1a is composed of multiple components including an outer joint member 30, an inner joint member 41, multiple third balls 50 which are multiple third rolling bodies, and a retainer 51. The constant velocity universal joint 1a is a joint with a fixed joint center, and the multiple third balls 50 serve as torque transmission members. The rolling bearing 1b is composed of multiple components including an outer ring 10, a hub 20, an outer joint member 30, multiple first balls 60 which are multiple first rolling bodies, and multiple second balls 70 which are multiple second rolling bodies.

The outer ring 10 is formed in a substantially cylindrical shape. The inner peripheral surface of the outer ring 10 is provided with annular raceway surfaces 11, 12 formed in two rows spaced apart in the axial direction X. The raceway surface 11 is a raceway surface for a plurality of first balls 60. The raceway surface 12 is a raceway surface for a plurality of second balls 70. The outer ring 10 is fixed to the vehicle body member 2 by bolts (not shown). The vehicle body member 2 is, for example, a member called a "knuckle."

The hub 20 is formed in an annular shape. The connecting portion 35 of the outer joint member 30 is inserted into the inner circumference of the hub 20. A number of bolts 22 are fixed to the hub 20, and the wheels 3, which serve as drive wheels, are attached to the hub 20 via the bolts 22.

2. Structure of the outer joint member 30 The outer joint member 30 is a member called an outer race of the constant velocity universal joint 1a. The outer joint member 30 has a cylindrical portion (joint portion) 31 having a bottom and a connecting portion 35 that is connected to the hub 20 so as to be capable of transmitting torque. The cylindrical portion 31 and the connecting portion 35 are integrated together.

The cylindrical portion 31 of the outer joint member 30 is formed in a cup shape having a bottom surface. The cylindrical portion 31 and the hub 20 are fitted together at the fitting portion 36 by pressing in the axial direction X. At this time, a gap may be formed in the fitting portion 36 to allow the hub 20 and the outer joint member 30 to be positioned. The cylindrical portion 31 has an internal space 31a and an abutment surface 31b that abuts against the hub 20 in the axial direction X. The abutment surface 31b is formed at an intermediate position between the first inner raceway surface 33 provided on the cylindrical portion 31 and the second inner raceway surface 21 provided on the hub 20. In other words, the first inner raceway surface 33 is disposed on the shaft 40 side of the abutment surface 31b, and the second inner raceway surface 21 is disposed on the wheel 3 side of the abutment surface 31b. Therefore, the first ball 60 is disposed on one side in the axial direction X, and the second ball 70 is disposed on the other side in the axial direction X, with a virtual plane (not shown) passing through the abutment surface 31b in between. The abutment surface 31b is disposed so as to overlap with the internal space 31a in the radial direction Y, that is, so as to be located within the axial direction X range of the internal space 31a. Arranging the abutment surface 31b in this manner is effective in keeping the axial direction X dimension of the connecting portion 35 of the outer joint member 30 short.

The inner surface in the radial direction Y of the cylindrical portion 31 of the outer joint member 30 is provided with a plurality of outer guide grooves 32 that guide the plurality of third balls 50 along the axial direction X. The plurality of outer guide grooves 32 are formed at equal intervals in the circumferential direction Z of the cylindrical portion 31. The first inner raceway surface 33 is provided on the outer surface in the radial direction Y of the cylindrical portion 31 of the outer joint member 30 so as to overlap with the internal space 31a in order to guide the plurality of first balls 60 in the circumferential direction Z. The first inner raceway surface 33 is formed in an annular shape in the circumferential direction Z of the cylindrical portion 31.

The connecting portion 35 of the outer joint member 30 engages with the hub 20 by what is called "spline fitting (a structure in which concave grooves on the inner circumferential surface of a splined hole or bore engage with convex teeth on the outer circumferential surface of a splined shaft)" and connects the outer joint member 30 and the hub 20 in a manner that allows torque transmission. The connecting portion 35 is also fastened and fixed to the hub 20 by a bolt 23 so that it cannot move relative to the hub in the axial direction. The head 23 of the bolt 23 abuts against the hub 20, and the male thread on the shaft portion 23 b extending from the head 23 a of the bolt 23 screws into the female thread on the recess 35 a of the connecting portion 35, thereby fastening and fixing the outer joint member 30 and the hub 20.

3. Structure of the inner joint member 41 The inner joint member 41 is formed in an annular shape and is fixed to the outer periphery of the shaft 40 connected to the drive source (electric motor or internal combustion engine) of the vehicle. The inner joint member 41 is accommodated in the internal space 31a of the cylindrical portion 31 of the outer joint member 30. The inner joint member 41 is capable of tilting relative to the outer joint member 30 around a predetermined joint center point P. In this embodiment, the angle between the central axis L1 of the outer joint member 30 and the central axis L2 of the inner joint member 41 is the joint angle. Note that FIG. 1 shows a state in which the joint angle is zero degrees.

4. Structure of the third ball 50 The third balls 50 are spheres of the same shape. The third balls 50 are housed in the internal space 31a of the cylindrical portion 31 of the outer joint member 30. The third balls 50 have a function of connecting the cylindrical portion 31 of the outer joint member 30 and the inner joint member 41 in a manner enabling torque transmission. One third ball 50 is guided by one outer guide groove 32. The number of the outer guide grooves 32 and the third balls 50 is six or eight.

5. Structure of the first balls 60 As shown in Fig. 1 and Fig. 2, the first balls 60 are spherical bodies of the same shape. The first balls 60 are provided between the raceway surface 11 of the outer ring 10 and the first inner raceway surface 33 of the outer joint member 30. The first balls 60 have a function of supporting the outer ring 10 and the outer joint member 30 so as to be relatively rotatable in the direction D around the axis (see Fig. 1). The number of the first balls 60 is not limited to 20 as shown in Fig. 2, but is set to an appropriate number.

6. Structure of the second balls 70 As shown in FIG. 1 and FIG. 3, the second balls 70 are spheres of the same shape. The second balls 70 are provided between the raceway surface 12 of the outer ring 10 and the second inner raceway surface 21 of the hub 20. The second balls 70 have a function of supporting the outer ring 10 and the hub 20 so as to be relatively rotatable in the axial direction D (see FIG. 1). The second inner raceway surface 21 is provided on the outer surface of the hub 20 in the radial direction Y so as to overlap with the internal space 31a of the cylindrical portion 31 in order to guide the second balls 70 in the circumferential direction Z. The second inner raceway surface 21 is formed in an annular shape in the circumferential direction Z of the hub 20. The number of the second balls 70 is not limited to 20 as shown in FIG. 3, but is set to an appropriate number.

In addition, the first ball 60 and the second ball 70 may be cylindrical rollers, needles, or conical tapered rollers, in addition to spheres.

As shown in FIG. 4, each third ball 50 contacts the outer guide groove 32 at two contact positions 32a in the circumferential direction. The groove bottom 32b between the two contact positions 32a of the outer guide groove 32 forms a small gap between the third ball 50 and the groove bottom 32b. The surface between two adjacent outer guide grooves 32 is formed by the joint inner spherical surface 34.

5 , the cage 51 is formed in a cylindrical shape to hold a plurality of third balls 50. The cage 51 has spherical outer and inner peripheral surfaces, and is disposed between the joint inner spherical surface 34 provided on the cylindrical portion 31 of the outer joint member 30 and the joint outer spherical surface 42 provided on the inner joint member 41.

8. Lightweight Structure of Bearing Device 1 for Driving Wheel Next, the lightweight structure characteristic of the bearing device 1 of this embodiment will be described with reference to Figures 5 to 15. The bearing device 1 does not have a separate member (such as a member called an "inner ring" or "hub inner ring") between the outer joint member 30 and the first balls 60, which is advantageous for weight reduction. The bearing device 1 of this embodiment is equipped with the following first to eighth lightweight structures to further reduce weight.

8-1. First lightweight structure As shown in Fig. 5, the first lightweight structure is a structure in which the first inner raceway surface 33 is disposed on the outer side of the outer guide groove 32 in the radial direction Y in the outer joint member 30 so as to overlap at least a part of the outer guide groove 32. In Fig. 5, for convenience of explanation, the region in which the outer guide groove 32 extends along the axial direction X is shown as a hatched region A, and the region in which the first inner raceway surface 33 extends along the arc surface is shown as a hatched region B. In this embodiment, the region B in which the first inner raceway surface 33 extends along the arc surface completely overlaps in the radial direction Y with the region A in which the outer guide groove 32 extends along the axial direction X. Alternatively, a part of the region B may overlap in the radial direction Y with the region A.

The first lightweight structure makes it possible to realize a narrower structure in which the outer guide groove 32 and the first inner raceway surface 33 are closer to the axial direction X than in the conventional structure. In this case, the dimension of the connecting portion 35 of the outer joint member 30 in the axial direction X can be shortened. This makes it possible to reduce the weight of the bearing device 1.

6, the second lightweight structure is a structure in which, in the outer joint member 30, the first inner raceway surface 33 is disposed on a vertical line L4 perpendicular to the tangent line L3 of the outer guide groove 32. The tangent line L3 is typically a tangent line at the groove bottom 32b (see FIG. 4) of the outer guide groove 32. In addition, this tangent line L3 may be a tangent line to the path of the contact position 32a (see FIG. 4) of the outer guide groove 32, or may be a tangent line to the path of the center of the third ball 50.

As with the first lightweight structure, the second lightweight structure allows the axial dimension of the connecting portion 35 of the outer joint member 30 to be shortened, making it possible to reduce the weight of the bearing device 1.

7, the third lightweight structure is a structure in which the angle θa between a virtual straight line L5 and the central axis L1 of the outer joint member 30 is set to 60 to 80 degrees. The virtual straight line L5 is a straight line that virtually connects the joint center point P of the inner joint member 41 and the center Q2 of the first ball 60.

As with the first lightweight structure, the third lightweight structure allows the axial dimension of the connecting portion 35 of the outer joint member 30 to be shortened, making it possible to reduce the weight of the bearing device 1. In particular, the greater the angle θa is set, the greater the effect of reducing the weight of the bearing device 1.

7, the fourth lightweight structure is a structure in which the angle θb between a virtual line L6 and the central axis L1 of the outer joint member 30 is set to 35 to 75 degrees when the joint angle is zero degrees (the state shown in FIG. 1). The virtual line L6 is a line that virtually connects the center Q1 of the third ball 50 and the center Q2 of the first ball 60.

As with the first lightweight structure, the fourth lightweight structure allows the axial dimension of the connecting portion 35 of the outer joint member 30 to be shortened, making it possible to reduce the weight of the bearing device 1. In particular, the greater the angle θb is set, the greater the effect of reducing the weight of the bearing device 1.

8-5. Fifth Lightweight Structure As shown in Fig. 8, the fifth lightweight structure is a structure in which, in a steady state where the joint angle is in a normal range, the third ball 50 contacts the cylindrical portion 31 of the outer joint member 30 in a contact area C, and the contact area C is located on a vertical line L8 perpendicular to a tangent line L7 of the first inner raceway surface 33. The steady state here refers to when the vehicle is stopped or moving straight. The tangent line L7 is a tangent line at the contact point between the first inner raceway surface 33 and the third ball 50. For convenience of explanation, the contact area C is shown as a hatched area in Fig. 8.

As with the first lightweight structure, the fifth lightweight structure allows the axial dimension of the connecting portion 35 of the outer joint member 30 to be shortened, making it possible to reduce the weight of the bearing device 1.

9, the sixth lightweight structure is a structure in which the angle θc between the imaginary line L9 and the central axis L1 of the outer joint member 30 is set to 40 to 60 degrees. The imaginary line L9 is a line that imaginarily connects the joint center point P of the inner joint member 41 and the center Q3 of the second ball 70.

As with the first lightweight structure, the sixth lightweight structure allows the axial dimension of the connecting portion 35 of the outer joint member 30 to be shortened, making it possible to reduce the weight of the bearing device 1. In particular, the greater the angle θc is set, the greater the effect of reducing the weight of the bearing device 1.

9, the seventh lightweight structure is a structure in which the angle θd between a virtual line L10 and the central axis L1 of the outer joint member 30 is set to 15 to 55 degrees when the joint angle is zero degrees (the state of FIG. 1). The virtual line L10 is a line that virtually connects the center Q1 of the third ball 50 and the center Q3 of the second ball 70.

As with the first lightweight structure, the seventh lightweight structure allows the axial dimension of the connecting portion 35 of the outer joint member 30 to be shortened, making it possible to reduce the weight of the bearing device 1. In particular, the greater the angle θd is set, the greater the effect of reducing the weight of the bearing device 1.

The eighth weight-saving structure is a structure for reducing the thickness of the cylindrical portion 31 of the outer joint member 30 in the radial direction Y to thereby reduce the weight of the bearing device 1. For the eighth weight-saving structure, reference is made to Figs. 10 to 15.

Figures 10 and 11 show the state of the bearing device 1 when traveling straight when the wheel 3 is the right front wheel. This state is a steady state in which the joint angle α is within the normal range (for example, a value of about 6 degrees), and the inner joint member 41 is located, for example, in the first position R1. The same is true when the vehicle is stopped. In contrast, Figures 12 and 13 show the state of the bearing device 1 when turning left when the wheel 3 is the right front wheel. This state is a variable state in which the joint angle α is a value outside the normal range (for example, a value of up to about 25 degrees), and the inner joint member 41 is located, for example, in the second position R2.

As shown in Figures 11 and 13, the eighth lightweight structure is a structure that satisfies the condition that the inner contact direction Ea and the outer contact direction Eb do not coincide in a cross section including the central axes L1, L2 of the outer joint member 30 and the inner joint member 41. In other words, the inner contact direction Ea and the outer contact direction Eb are not coincident not only in three dimensions, but also when viewed two-dimensionally in the cross section.

The inner contact direction Ea is the contact direction of the first ball 60 on the first inner raceway surface 33 of the cylindrical portion 31 of the outer joint member 30. The first ball 60 contacts the first inner raceway surface 33 at a contact position 33a (the area shown by the cross section of a substantially elliptical shape in Figs. 11 and 13) at a contact angle β (angle with respect to a virtual line in the radial direction Y) and inputs a load in the inner contact direction Ea to the first inner raceway surface 33. The contact angle β is, for example, about 40 degrees when traveling straight (see Fig. 11), and about 52 degrees when turning left (see Fig. 13). At this time, stress is generated in the first inner raceway surface 33 of the cylindrical portion 31 due to the load input from the first ball 60. The inner contact direction Ea can also be called the load input direction from the first ball 60.

The outer contact direction Eb is the contact direction of the third ball 50 in the outer guide groove 32 of the cylindrical portion 31 of the outer joint member 30. In the case of a joint angle α, the center of the third ball 50 is located on a line passing through the joint center point P and inclined by α/2, which is 1/2 of the joint angle α, from a plane passing through the joint center point P and perpendicular to the central axis L1, and the third ball 50 contacts the outer guide groove 32 at a contact angle γ (angle with respect to a virtual line in the radial direction Y) larger than α/2 at the contact position 32a (area shown by a cross section of a substantially ellipse in Figures 11 and 13), and inputs a load in the outer contact direction Eb to the outer guide groove 32. At this time, stress due to the load input from the third ball 50 is generated in the outer guide groove 32 of the cylindrical portion 31. The outer contact direction Eb can also be called the load input direction from the third ball 50.

Here, if the inner contact direction Ea and the outer contact direction Eb coincide, it is assumed that local stress concentration will occur in the portion of the tubular portion 31 of the outer joint member 30 where the inner contact direction Ea and the outer contact direction Eb coincide. If measures are taken to increase the thickness of the tubular portion 31 so that it can withstand this stress concentration, this could cause the weight of the bearing device 1 to increase. Therefore, in the eighth lightweight structure, the inner contact direction Ea and the outer contact direction Eb are not made to coincide, thereby suppressing the above-mentioned stress concentration in the tubular portion 31 of the outer joint member 30. This makes it possible to reduce the thickness of the tubular portion 31 and reduce the weight of the bearing device 1.

11 and 13, when the extension line extending from the center of the first ball 60 in the inner contact direction Ea is defined as the first extension line M1, multiple first extension lines M1 are formed according to the number of the first balls 60. Here, the first extension line M1 is a line that linearly connects the center of the first ball 60 and the contact position 33a of the first ball 60 on the first inner raceway surface 33. Also, when the extension line extending from the center of the third ball 50 in the outer contact direction Eb is defined as the third extension line M3, multiple third extension lines M3 are formed according to the number of the third balls 50. Here, the third extension line M3 is a line that linearly connects the center of the third ball 50 and the contact position 32a of the third ball 50 on the outer guide groove 32.

The eighth lightweight structure is preferably a structure that satisfies the following conditions: if the multiple first extension lines M1 include one that passes through the contact position 32a of the third ball 50 in the outer guide groove 32, the third extension line M3 for the third ball 50 at that contact position 32a does not pass through the contact position 33a of the first ball 60 in the first inner raceway surface 33; and if the multiple third extension lines M3 include one that passes through the contact position 33a of the first ball 60 in the first inner raceway surface 33, the first extension line M1 for the first ball 60 at that contact position 33a does not pass through the contact position 32a of the third ball 50 in the outer guide groove 32.

In this structure, for example, as shown in FIG. 14, one of the three first extension lines M1 passes through the contact position 32a of the third ball 50 in the outer guide groove 32, but the third extension line M3 for the third ball 50 at that contact position 32a does not pass through the contact position 33a of any of the first balls 60 in the first inner raceway surface 33. Also, one third extension line M3 passes through the contact position 33a of the first ball 60 in the first inner raceway surface 33, but the first extension line M1 for the first ball 60 at that contact position 33a does not pass through the contact position 32a of any of the third balls 50 in the outer guide groove 32.

Furthermore, the eighth lightweight structure is preferably a structure that satisfies the condition that, during rotation in which the joint angle α exceeds the normal range (see Figures 12 and 13), the first extension line M1 of the first ball 60 that has the greatest input load on the first inner raceway surface among the multiple first balls 60 does not pass through the contact position 32a in the outer guide groove 32 of any of the multiple third balls 50.

In this structure, for example, as shown in FIG. 15, when the top of the figure is the top of the vehicle, the first ball 60 at the first position S1, which is the highest of the three first balls 60, receives the largest load F from the vehicle side, compared to the first balls 60 at the second position S2 and the third position S3, which are lower than the first position S1. Therefore, the first ball 60 at the first position S1 receives the largest input load on the first inner raceway surface 33 among the three first balls 60, and at this time, the first extension line M1 of the first ball 60 at the first position S1 does not pass through the contact position 32a in the outer guide groove 32 of any of the multiple third balls 50.

9. Effects According to the above-described first embodiment, the following effects can be obtained.

In the bearing device 1 of the first embodiment, a first inner raceway surface 33 that guides the first balls 60 in the circumferential direction Z is provided on the outer surface in the radial direction Y of the cylindrical portion 31 of the outer joint member 30, and an outer guide groove 32 that guides the third balls 50 along the axial direction X is provided on the inner surface in the radial direction Y of the cylindrical portion 31 of the outer joint member 30. According to the structure in which the first ball 60 is in direct contact with the cylindrical portion 31 of the outer joint member 30, no separate member is interposed between the first ball 60 and the outer joint member 30, and therefore the weight can be reduced accordingly. In addition, the bearing device 1 is provided with the first to eighth lightweight structures, which allows the weight of the bearing device 1 to be further reduced.

As described above, according to the above-mentioned embodiment 1, the weight of the bearing device 1 can be reduced. As a result, it is possible to extend the driving range of a vehicle equipped with the bearing device 1 and improve the electricity consumption or fuel consumption.

10. Modifications Although the present disclosure has been described based on the above-mentioned embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

In the above embodiment, the bearing device 1 is provided with the first to eighth lightweight structures, but if necessary, the bearing device 1 may be provided with at least one of the first to eighth lightweight structures.

In the above embodiment, the connecting portion 35 of the outer joint member 30 and the hub 20 are connected to each other so that torque can be transmitted by spline engagement, but a connecting method other than spline engagement may be used instead.

Claims (5)

An outer ring (10) fixed to a vehicle body side member (2);
a hub (20) to which the wheel (3) is attached;
an outer joint member (30) having a cylindrical portion (31) with a bottom and a connecting portion (35) connected to the hub so as to be capable of transmitting torque;
an inner joint member (41) accommodated in the cylindrical portion of the outer joint member;
a plurality of first rolling bodies (60) provided between the outer ring and the outer joint member and supporting the outer ring and the outer joint member so as to be relatively rotatable in a direction around an axis (D);
A plurality of second rolling elements (70) are provided between the outer ring and the hub and support the outer ring and the hub so as to be capable of relative rotation in a direction around the axis (D);
a plurality of third rolling bodies (50) that connect the cylindrical portion of the outer joint member and the inner joint member in a torque-transmittable manner;
Equipped with
an outer guide groove (32) that guides the third rolling elements along an axial direction (X) is provided on an inner surface in a radial direction (Y) of the cylindrical portion of the outer joint member;
a first inner raceway surface (33) that guides the first rolling elements in a circumferential direction (Z) is provided on a radial outer surface of the cylindrical portion of the outer joint member,
In the outer joint member, the first inner raceway surface is arranged radially outwardly of the outer guide groove so as to overlap at least a portion of the outer guide groove, or the first inner raceway surface is arranged on a vertical line (L4) perpendicular to a tangent line (L3) of the outer guide groove. The bearing device for a driving wheel according to claim 1, in which, in a cross section including the central axes (L1, L2) of the outer joint member and the inner joint member, when the contact direction of the first rolling body on the first inner raceway surface is defined as an inner contact direction (Ea) and the contact direction of the third rolling body on the outer guide groove is defined as an outer contact direction (Eb), the inner contact direction and the outer contact direction do not coincide. When an extension line extending from the center of the first rolling body in the inner contact direction is defined as a first extension line (M1), and an extension line extending from the center of the third rolling body in the outer contact direction is defined as a third extension line (M3),
When one of the plurality of first extension lines passes through a contact position (32a) of the third rolling body on the outer guide groove, the third extension line of the third rolling body at the contact position does not pass through a contact position (33a) of the first rolling body on the first inner raceway surface,
3. A bearing device for a driving wheel as described in claim 2, wherein, when the multiple third extension lines include one that passes through the contact position (33a) of the first rolling body on the first inner raceway surface, the first extension line for the first rolling body at that contact position does not pass through the contact position (32a) of the third rolling body on the outer guide groove. The driving wheel bearing device according to claim 3, wherein, during rotation in which the joint angle (α), which is the angle between the central axis (L1) of the outer joint member and the central axis (L2) of the inner joint member, exceeds the normal range, the first extension line of the first rolling body that has the largest input load on the first inner raceway surface among the plurality of first rolling bodies does not pass through the contact position (32a) in the outer guide groove of any of the plurality of third rolling bodies. The bearing device for a driving wheel according to any one of claims 1 to 4, wherein in a steady state in which a joint angle (α), which is the angle between the central axis (L1) of the outer joint member and the central axis (L2) of the inner joint member, is in a normal range, the third rolling element contacts the cylindrical portion of the outer joint member in a contact range (C), and the contact range is located on a vertical line (L8) perpendicular to a tangent (L7) of the first inner raceway surface.

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