JP6657586B2 - Inner shaft as a component of hub unit, inner ring member as a component of hub unit, and method of manufacturing hub unit - Google Patents

Description

  The present invention relates to a hub unit and a method for manufacturing the same.

A hub unit is used to rotatably support wheels of a vehicle with respect to a suspension device. The hub unit includes a rolling bearing and a hub wheel having a cylindrical hub shaft that serves as a raceway member of the rolling bearing (for example, see Patent Document 1).
The hub shaft described in Patent Literature 1 includes an inner shaft integrally having a flange portion, and an inner ring member fitted on an outer peripheral surface of a small-diameter portion that forms a part of the inner shaft in the axial direction. The position of the inner ring member in the axial direction is fixed by a caulking portion obtained by plastically deforming the axial end of the inner shaft radially outward.

JP 2014-24506 A

  As shown in FIG. 6, when the axial end of the inner shaft 121 is plastically deformed radially outward to form the caulked portion 124, the small-diameter portion 123 of the inner shaft 121 is distorted radially inward, and the small-diameter portion 123 is deformed. A gap S may be formed between the outer peripheral surface and the inner peripheral surface of the inner ring member 132, and the degree of adhesion between the two may decrease. Such a decrease in the degree of adhesion leads to a decrease in the holding force of the inner ring member 132 and causes creep of the inner ring member 132, which is not preferable.

  The present invention has been made in view of the above circumstances, and provides a hub unit capable of suppressing a decrease in the degree of adhesion between an inner ring member and a small-diameter portion of an inner shaft by forming a caulked portion, and a method of manufacturing the same. Aim.

The present invention is an inner shaft that is a component of a hub unit, wherein the inner shaft has a small diameter portion in a part in the axial direction, and the inner shaft is an inner ring member that is another component of the hub unit. Before being assembled, the outer peripheral surface of the small-diameter portion of the inner shaft is disposed on both sides in the axial direction of the bulging surface, which bulges outwardly in a convex shape and bulges, and the hub A cylindrical cylindrical surface having a constant radius around the axis of the unit, and is disposed between the bulging surface and the cylindrical surface, and is concavely curved to smoothly connect the bulging surface and the cylindrical surface. And the entire outer peripheral surface of the small diameter portion is in close contact with the entire inner peripheral surface of the inner ring member when assembled with the inner ring member .
The present invention is an inner ring member that is a component of a hub unit, wherein an inner peripheral surface of the inner ring member is a bulging surface that curves and protrudes radially inward and bulges, and an axis of the bulging surface. A cylindrical surface having a constant radius around the axis of the hub unit, and disposed between the swelling surface and the cylindrical surface, the swelling surface being curved in a concave shape. have a connection surface that smoothly connects the cylindrical surface, the entire inner peripheral surface of the inner ring member is brought into close contact with the entire outer peripheral surface of the shaft within the which is another component of the hub unit.

  According to the present invention, it is possible to suppress a decrease in the degree of adhesion between the inner ring member and the small diameter portion of the inner shaft due to the formation of the caulked portion.

It is a sectional view of a hub unit concerning a 1st embodiment of the present invention. FIG. 2 is an enlarged sectional view showing an inner shaft and an inner ring member of the hub unit shown in FIG. 1. It is sectional drawing which shows the state before fitting an inner ring member to the small diameter part of an inner shaft. It is explanatory drawing which shows the bulge surface, the cylindrical surface, and the connection surface formed in the inner shaft. It is a sectional view expanding and showing an inner axis and an inner ring member of a hub unit concerning a 2nd embodiment of the present invention. It is sectional drawing which expands and shows the inner shaft and inner ring member of the hub unit which concerns on a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a hub unit according to the first embodiment of the present invention. In this specification, the left-right direction in FIG. 1 is referred to as an axial direction of the hub unit 10, the left side in FIG. 1 is referred to as a vehicle outer side (or an axially outer side), and the right side is referred to as a vehicle inner side (or an axially inner side).

The hub unit 10 rotatably supports, for example, wheels of an automobile with respect to a suspension device on a vehicle body side. The hub unit 10 includes a rolling bearing 11 and a hub wheel 12 having a race member of the rolling bearing 11.
The hub wheel 12 has a hub shaft 20 and a flange portion 26. The hub shaft 20 is formed in a cylindrical shape, and functions as an inner ring of the rolling bearing 11. The hub shaft 20 has an inner shaft 21 and an inner ring member 32.

  The inner shaft 21 has a large diameter portion 22, a small diameter portion 23, and a caulking portion 24 integrally. The large-diameter portion 22 of the inner shaft 21 is arranged on the vehicle outer side, and the small-diameter portion 23 is arranged on the vehicle inner side. The small diameter portion 23 is formed continuously inside the large diameter portion 22 in the axial direction. Further, the outer diameter of the small diameter portion 23 is smaller than the outer diameter of the large diameter portion 22. The caulking part 24 is plastically deformed so that the axial end of the inner shaft 21 closer to the vehicle inner side than the small diameter part 23 is bent radially outward.

The inner ring member 32 is fitted so that the inner peripheral surface 32c is in close contact with the outer peripheral surface 23c of the small diameter portion 23.
The flange portion 26 protrudes radially outward from a radially outer end of the large diameter portion 22. A plurality of bolt holes 26a penetrating in the thickness direction are formed in the flange portion 26 in the circumferential direction. Hub bolts 27 for mounting a wheel or a brake disc (not shown) are press-fitted into the bolt holes 26a, respectively.

The rolling bearing 11 is a double-row ball bearing. The rolling bearing 11 includes an outer ring 31, the above-described hub shaft 20 that forms an inner ring, a plurality of balls (rolling elements) 33, and a retainer 34.
The outer race 31 has a pair of outer raceway surfaces 31a and 31b on its inner peripheral surface. The pair of outer raceway surfaces 31a and 31b are arranged side by side in the axial direction. A fixed flange 35 for attaching the hub unit 10 to a vehicle body-side member (not shown) supported by a suspension device is formed on the outer peripheral surface of the outer race 31.

The inner race member 32 of the hub axle 20 has an inner raceway surface 32a on its outer peripheral surface. The inner raceway surface 32a faces radially inward of the outer raceway surface 31a on the vehicle inner side.
The large-diameter portion 22 of the inner shaft 21 of the hub shaft 20 has an inner raceway surface 22b on its outer peripheral surface. The inner raceway surface 22b faces radially inward of the outer raceway surface 31b on the vehicle outer side.

The plurality of balls 33 are rotatably arranged between the outer raceway surface 31a and the inner raceway surface 32a and between the outer raceway surface 31b and the inner raceway surface 22b. Therefore, the plurality of balls 33 are arranged in two rows in the axial direction.
A pair of retainers 34 are provided corresponding to the two rows of balls 33, respectively. Each retainer 34 holds the plurality of balls 33 in each row at predetermined intervals in the circumferential direction.

FIG. 2 is an enlarged sectional view showing the inner shaft 21 and the inner ring member 32 of the hub unit 10 shown in FIG.
The inner ring member 32 has an inner peripheral surface 32 c extending substantially parallel to the axis C of the hub unit 10. On the vehicle inner side and the vehicle outer side with respect to the inner peripheral surface 32c, rounded surfaces 32d and 32e which are respectively curved in an arc shape are formed.

  On the other hand, the small-diameter portion 23 of the inner shaft 21 has an outer peripheral surface 23c extending substantially parallel to the axis C of the hub unit 10. The outer peripheral surface 24d of the caulking portion 24 formed closer to the vehicle inner side than the small diameter portion 23 is curved in an arc shape along the radius surface 32d of the inner ring member 32, and is in close contact with the radius surface 32d. Further, on the vehicle outer side of the outer peripheral surface 23c of the small diameter portion 23, a round surface 23e which is curved in an arc shape along the round surface 32e of the inner ring member 32 and is in close contact with the round surface 32e is formed.

  Almost the entire inner circumferential surface 32c of the inner ring member 32 in the axial direction is fitted to the outer circumferential surface 23c of the small diameter portion 23 in a tight fit, and is in close contact with the outer circumferential surface 23c. That is, the interference is provided between the inner diameter of the inner ring member 32 and the outer diameter of the small diameter portion 23. Therefore, relative rotation of the inner race member 32 in the circumferential direction with respect to the small-diameter portion 23 is restricted, and occurrence of creep is prevented.

FIG. 3 is a cross-sectional view showing a state before the inner ring member 32 is fitted to the small-diameter portion 23 of the inner shaft 21.
Before forming the caulked portion 24 (see FIG. 2) by plastic deformation, the axial end portion 24 ′ of the inner shaft 21 extends in the axial direction continuously to the vehicle inner side of the small-diameter portion 23. Then, as shown by the arrow X, after the inner ring member 32 is fitted to the small diameter portion 23, the axial end 24 ′ of the inner shaft 21 is moved radially outward (in the direction of arrow a) by using a jig (not shown). ) To form a caulked portion 24 having a shape along the radius surface 32d. Thus, the hub wheel 12 of the hub unit 10 is manufactured.

  When the caulking portion 24 is formed by plastically deforming the axial end portion 24 ′ of the inner shaft 21, the small-diameter portion 23 of the inner shaft 21 is on the opposite side (radially inward) to the direction a in which the caulking portion 24 is bent. Causes some distortion. Conventionally, as shown in FIG. 6, a gap S is generated between the inner ring member 132 and the small diameter portion 123 due to distortion of the small diameter portion 123 of the inner shaft 121, and the outer peripheral surface of the small diameter portion 123 and the inner peripheral surface of the inner ring member 132 Therefore, there is a problem that the degree of adhesion between the inner ring member 132 and the inner ring member 132 decreases.

In the hub unit 10 of the present embodiment, as shown in FIGS. 3 and 4, at the stage of manufacturing the inner shaft 21, the outer peripheral surface 23 c of the small-diameter portion 23 has the bulging surface 23 c 1, the cylindrical surface 23 c 2, and the connection surface 23 c 3. It is formed to have.
The swelling surface 23c1 bulges in a convex shape outward in the radial direction. Specifically, the bulging surface 23c1 of the present embodiment bulges outward in the radial direction in an arc-shaped cross section.

Further, the cylindrical surface 23c2 is disposed on the vehicle inner side and the vehicle outer side with respect to the bulging surface 23c1, and is formed in a cylindrical shape having a constant radius around the axis C of the hub unit 10.
Further, the connection surface 23c3 is disposed between the bulging surface 23c1 and the cylindrical surface 23c2, and is formed to be concavely curved. The connection surface 23c3 smoothly connects the swelling surface 23c1 and the cylindrical surface 23c2 so that the cross-sectional shape does not suddenly change between the swelling surface 23c1 and the cylindrical surface 23c2. The connection surface 23c3 of the present embodiment is a round surface having a circular arc cross section.

The connection surface 23c3 on the vehicle inner side is disposed closer to the vehicle outer side than the starting point P of the caulking portion 24 (the boundary between the outer peripheral surface 23c of the small diameter portion 23 and the round surface 24d). However, the connection surface 23c3 may overlap with the starting point P.
The radius of curvature of the cross-section arc of the bulging surface 23c1 can be set to, for example, 250 mm. The radius of curvature of the circular arc of the cross section of the connecting surface 23c3 at the boundary between the bulging surface 23c1 and the cylindrical surface 23c2 can be set to, for example, 10 mm.

  By forming the swelling surface 23c1 as described above on the outer peripheral surface 23c of the small-diameter portion 23, even if the small-diameter portion 23 is distorted radially inward due to the formation of the caulking portion 24, the entire outer peripheral surface 23c is formed on the inner race member 32. Can be tightly fitted to the inner peripheral surface 32c of the diaper. Therefore, the degree of adhesion between the outer peripheral surface 23c of the small diameter portion 23 and the inner peripheral surface 32c of the inner ring member 32 does not decrease, and the holding force of the inner ring member 32 can be maintained.

  In addition, in this specification, the "adhesion degree" refers to the degree of close contact between the outer peripheral surface 23c of the small diameter portion 23 and the inner peripheral surface 32c of the inner ring member 32. For example, the two 23c and 32c contact each other without gaps. The size of the area can be used as an index. The “holding force” refers to a force of the inner shaft 21 holding the inner ring member 32 so that the inner shaft 21 and the inner ring member 32 do not rotate relative to each other. The friction force generated between the inner peripheral surface 32c and the inner peripheral surface 32c can be used as an index.

  As shown in FIG. 4, the bulging amount H of the bulging surface 23 c 1, that is, the height of the vertex of the bulging surface 23 c 1 with respect to the cylindrical surface 23 c 2, even if the small-diameter portion 23 is distorted radially inward. The dimension is set such that an interference fit is maintained with the surface 32c. Specifically, the amount of distortion of the small-diameter portion 23 when the caulking portion 24 is formed is experimentally obtained, and the amount H of the bulging surface 23c1 can be set based on the amount of distortion. For example, the swelling amount H can be set within a range of 5.0 μm to 70.0 μm. In addition, the cylindrical surface 23c2 arranged on the vehicle inner side and the vehicle outer side with respect to the bulging surface 23c1 is also formed with an outer diameter dimension that can be tightly fitted between the cylindrical surface 23c2 and the inner peripheral surface 32c of the inner ring member 32.

  Generally, the outer peripheral surface 23c of the small diameter portion 23 of the inner shaft 21 is formed by polishing or cutting. Conventionally, since the outer peripheral surface of the small diameter portion does not have the swelling surface and the connecting surface as in the present embodiment, only the cylindrical surface is machined. In the present embodiment, the bulging surface 23c1 and the connection surface 23c3 are formed by the same process as the cylindrical surface 23c2 by polishing or cutting. Therefore, the number of steps does not increase as compared with the related art in forming the swelling surface 23c1 and the connection surface 23c3.

FIG. 5 is an enlarged sectional view showing an inner shaft and an inner ring member of the hub unit according to the second embodiment of the present invention.
In the first embodiment, the outer peripheral surface 23c of the small diameter portion 23 of the inner shaft 21 has the bulging surface 23c1, but in the present embodiment, the inner peripheral surface 32c of the inner ring member 32 has the bulging surface 32c1. ing. The inner peripheral surface 32c of the inner ring member 32 has a cylindrical surface 32c2 having a constant radius on the vehicle outer side and the vehicle inner side with respect to the bulging surface 32c1. Further, the inner peripheral surface 32c of the inner ring member 32 has a connection surface 32c3 between the bulging surface 32c1 and the cylindrical surface 32c2 for smoothly connecting the both.

The swelling surface 32c1 and the connection surface 32c3 differ from the swelling surface 23c1 and the connection surface 32c3 in the first embodiment only in the direction in which the swelling surface 32c1 and the connection surface 32c3 swell. Bulging surface 23c1 and connecting surface 32c3.
Also in the present embodiment, the bulging surface 32c1, the cylindrical surface 32c2, and the connecting surface 32c3 of the inner race member 32 are formed in the same process by polishing or cutting. Therefore, the number of steps does not increase due to the formation of the bulging surface 32c1 and the connecting surface 32c3.

  In the present embodiment, the crimped portion 24 is formed by plastically deforming the axial end portion 24 ′ of the inner shaft 21, so that even if the small-diameter portion 23 is distorted radially inward, the swelling surface is formed on the distorted portion. 32c1 enters, and the tight fit between the inner peripheral surface 32c of the inner ring member 32 and the outer peripheral surface 23c of the small diameter portion 23 is maintained. Therefore, the degree of adhesion between the outer peripheral surface 23c of the small diameter portion 23 and the inner peripheral surface 32c of the inner ring member 32 is not impaired, and the holding force of the inner ring member 32 can be maintained.

  The illustration of the swelling surfaces 23c1 and 32c1 in FIGS. 3 to 5 and the illustration of the gap S in FIG. 6 described in the above embodiment are exaggerated for easy understanding of their existence. . Therefore, not only their dimensions but also their relative proportions to other parts are different from the actual ones.

The present invention is not limited to the above embodiment, but can be appropriately modified within the scope of the invention described in the claims.
After the swollen portion is formed, the swollen surface may be formed on a surface substantially parallel to the axis C, or may be formed in a shape swollen in the radial direction. Further, the bulging surface is not limited to a circular arc shape having a constant radius of curvature, but may be a shape having a variable radius of curvature. The connection surface is not limited to a circular arc shape having a constant radius of curvature, but may be a shape having a variable radius of curvature.
The rolling bearing of the hub unit is not limited to a ball bearing, but may be a roller bearing.
The inner shaft of the hub unit is not limited to a cylindrical shape, and may be a solid shape.

  10: hub unit, 11: rolling bearing, 12: hub wheel, 21: inner shaft, 23: small diameter portion, 23c: outer peripheral surface, 23c1: bulging surface, 23c2: cylindrical surface, 23c3: connecting surface, 24: caulking portion, 32: inner ring member, 32c: inner peripheral surface, 32c1: bulging surface, 32c2: cylindrical surface, 32c3: connecting surface, H: bulging amount

Claims (7)

An inner shaft that is a component of the hub unit,
The inner shaft has a small diameter portion in a part of the axial direction,
In a state before the inner shaft is assembled with the inner ring member that is another component of the hub unit, the outer peripheral surface of the small-diameter portion of the inner shaft has a bulge that bulges outwardly in a convex shape. Projecting surface, disposed on both sides in the axial direction of the bulging surface, a cylindrical cylindrical surface having a constant radius around the axis of the hub unit, and disposed between the bulging surface and the cylindrical surface, concave A connecting surface that smoothly curves and connects the swelling surface and the cylindrical surface smoothly,
An inner shaft which is a component of the hub unit , wherein when assembled with the inner ring member, the entire outer peripheral surface of the small diameter portion is in close contact with the entire inner peripheral surface of the inner ring member .   The inner shaft as a component of the hub unit according to claim 1, wherein the swelling amount of the swelling surface is set within a range of 5.0 to 70.0 µm. An inner ring member that is a component of the hub unit,
An inner peripheral surface of the inner ring member is disposed on both sides in the axial direction of the bulging surface, which bulges convexly inward in the radial direction and bulges, and is fixed around the axis of the hub unit. a cylindrical cylindrical surface having a radius, said disposed between the bulged surface and said cylindrical surface, curved in a concave shape to have a connection surface that smoothly connects the cylindrical surface and the bulging surface,
An inner ring member, which is a component of the hub unit, wherein the entire inner peripheral surface of the inner ring member is in close contact with the entire outer peripheral surface of the inner shaft, which is another component of the hub unit.   The inner ring member as a component of the hub unit according to claim 3, wherein the swelling amount of the swelling surface is set within a range of 5.0 to 70.0 µm. An inner shaft having a small-diameter portion in an axial part thereof, and an inner ring member fitted to the outer peripheral surface of the small-diameter portion, and a caulking portion plastically deforming an axial end of the inner shaft radially outward. A method of manufacturing a hub unit, wherein the inner ring member is fixed to the inner shaft by:
One of an outer peripheral surface of the small-diameter portion and an inner peripheral surface of the inner ring member fitted to the outer peripheral surface, a bulging surface convexly curved and bulging toward the other side, and the bulging surface; A cylindrical cylindrical surface having a certain radius, disposed on both sides in the axial direction, and disposed between the swelling surface and the cylindrical surface, curved in a concave shape to smoothly smooth the swelling surface and the cylindrical surface. A first step of forming a connection surface to be connected,
After the first step, a second step of fitting the inner peripheral surface of the inner ring member on the outer peripheral surface of the small diameter portion,
After the second step, an axial end of the inner shaft is plastically deformed to form a caulked portion, and a third inner surface of the inner ring member is brought into close contact with the entire outer peripheral surface of the small diameter portion. And a method for manufacturing a hub unit.   The method of manufacturing a hub unit according to claim 5, wherein the bulging surface, the cylindrical surface, and the connecting surface are formed in the same process by polishing.   The method of manufacturing a hub unit according to claim 5, wherein the bulging surface, the cylindrical surface, and the connecting surface are formed in the same step by cutting.

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