JP2019209801A - Wheel bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sticking of a hub unit and a wheel due to rust while suppressing an increase in manufacturing cost. SOLUTION: This is a wheel bearing in which a pilot part 22 is integrally provided on either one of an inner shaft member 14 and an outer ring member 13 which is rotatable, and an outer peripheral surface 42 of the pilot part 22 has a single axial direction. A projecting portion 43 that projects radially outward is provided over the entire circumference of the portion. The protruding portion 43 has a top portion 44 formed of a curve that is convex outward in the radial direction. The top portion 44 is connected to the straight line 46 at the first continuous point 49 on the one axial direction side, and on the other axial direction side. The straight line 48 and the second continuous point 50 are connected. The angle between the tangent line of the apex 44 at the first continuous point 49 and the central axis and the angle between the tangent line of the apex 44 at the second continuous point 50 and the central axis are 45 ° or more and 67.5 ° or less, respectively. The center of the circle including the point P, which is the outermost point in the radial direction of the top portion 44, the first continuous point 49, and the second continuous point 50, is radially outward of the outer peripheral surface 42. [Selection diagram] Figure 2

Description

  The present invention relates to a wheel bearing.

In vehicles such as automobiles, for example, a hub unit in which a rolling bearing and a hub flange are integrated is used as a wheel bearing for rotating and supporting a wheel. The hub flange is provided with an annular guide portion (referred to as a pilot portion) protruding in the axial direction in order to attach the wheel and the brake rotor coaxially. A hole into which the pilot portion is inserted is formed in the center of the wheel.
Since the hub flange is made of carbon steel such as S55C, rust is generated in the pilot part when it is exposed to rain or accumulated water on the road. Since the hole of the wheel and the pilot part are fitted with a very small clearance, the fitting part of the wheel and the hub flange is fixed due to rust, and it may be difficult to detach the wheel.
Therefore, in order to prevent the wheel and the hub flange from sticking, measures have been devised in which the pilot part is coated or, as disclosed in Patent Document 1, the pilot part is formed of stainless steel having corrosion resistance. Yes.

JP 2008-68682 A

However, when painting the pilot part, a process such as masking is required to prevent the paint from adhering to other parts, which increases the manufacturing cost of the hub unit. Moreover, when providing a separate pilot part like patent document 1, it requires the expense for manufacturing the said pilot part, and it is necessary to form the attachment hole for incorporating a pilot part in a hub flange by machining This increases the manufacturing cost of the hub unit.
An object of the present invention is to prevent the hub unit and the wheel from sticking due to rusting and to make the wheel easy to attach and detach while suppressing an increase in manufacturing cost.

  The present invention can roll between an inner shaft member having a double row inner raceway groove on the outer periphery, an outer ring member having a double row outer raceway groove on the inner periphery, and the inner raceway groove and the outer raceway groove. A plurality of rolling elements disposed on the inner ring member, and one of the inner shaft member and the outer ring member rotates around a central axis with respect to the other of the inner shaft member and the outer ring member. A wheel bearing in which a substantially cylindrical pilot portion centered on a central axis is integrally provided on the one member, and the outer peripheral surface of the pilot portion is partly in the axial direction. Protrusions projecting radially outward are provided over the entire circumference, and the projecting part has a top part made of a curved curve radially outward in the axial section, and the top part is in one axial direction side. And connected to the outer peripheral surface via a first curve and / or a first straight line that is radially inwardly convex. And connected to the outer peripheral surface via a second curved line and / or a second straight line radially inward on the other side in the axial direction, and the top portion and the first curved line or the first straight line A second continuation in which an angle formed between a tangent line of the top portion and a central axis at a first continuity point where the continuity is connected is 45 ° or more and 67.5 ° or less, and the top portion and the second curve or the second straight line are connected. The angle between the tangent line of the apex at the point and the central axis is 45 ° or more and 67.5 ° or less, the outermost point in the radial direction of the apex, the first continuous point, and the second The center of a circle including a continuous point is characterized by being radially outward from the outer peripheral surface.

  According to the present invention, it is possible to suppress an increase in manufacturing cost, to prevent the hub unit and the wheel from sticking due to rusting, and to easily attach and detach the wheel.

It is sectional drawing which shows the axial cross section of the wheel bearing which carries out rotation support of the wheel. It is the principal part enlarged view which expanded the 1st guide surface of the pilot part in FIG. It is a schematic diagram explaining the range to which a 1st guide surface and the inner periphery of a wheel adhere.

An embodiment of the present invention (hereinafter, “this embodiment”) will be described with reference to the drawings. FIG. 1 shows an axial cross section of a wheel bearing for rotating and supporting a wheel of an automobile or the like. In this embodiment, a hub unit 10 in which a hub flange to which a wheel is attached and a rolling bearing are integrally combined is used as a wheel bearing. The hub unit 10 rotates around a central axis m that is parallel to the paper surface and extends in the left-right direction.
In the following description, the direction of the central axis m is referred to as the axial direction, the direction orthogonal to the central axis m is referred to as the radial direction, and the direction of circling around the central axis m is referred to as the circumferential direction. Moreover, in FIG. 1, the hub unit 10 is attached to the knuckle 11 of the vehicle, and the wheel 12 of the wheel is incorporated on the right side of the figure. For this reason, the left side in FIG. 1 may be referred to as an inner side or one axial direction side, and the right side may be referred to as an outer side or another axial direction side.

  The hub unit 10 includes a housing 13, an inner shaft 14, and a plurality of balls 15 (rolling elements).

  The housing 13 (outer ring member) has a substantially cylindrical shape, and is manufactured of a steel material such as carbon steel by hot forging or the like. A plurality of flanges 16 are formed integrally with the housing 13 and project radially from the outer periphery of the housing 13. Each flange 16 is provided with a screw hole penetrating in the axial direction. Two rows of outer raceway grooves 17 are formed on the inner circumference of the housing 13 over the entire circumference.

The inner shaft 14 (inner shaft member) has a configuration in which an inner ring 19 is press-fitted into the shaft end of the hub shaft 18. The hub shaft 18 is made of a steel material such as carbon steel by hot forging or the like, and a cylindrical shaft portion 20, a disc-shaped hub flange 21, and a pilot portion 22 are integrally formed.
A first inner raceway groove 23 is formed on the outer circumference of the shaft portion 20 over the entire circumference. A plurality of hub bolts 24 are incorporated in the axial direction on a predetermined pitch circle of the hub flange 21.

  The pilot portion 22 has a substantially cylindrical shape and is formed on the outer side of the hub flange 21. The outer periphery of the pilot portion 22 is machined into a predetermined shape, and a first guide surface 40 and a second guide surface 41 having different outer diameters are formed. The first guide surface 40 has a smaller diameter than the second guide surface 41 and is formed on the outer side from the second guide surface 41. The present embodiment is characterized by the shape of the pilot portion 22, particularly the shape of the first guide surface 40. The details of the pilot unit 22 will be described in detail after other configurations are described.

  The inner ring 19 is annular and is made of a steel material such as bearing steel, and is assembled to the inner side end of the shaft portion 20 in an interference fit state. A second inner raceway groove 25 is formed on the outer circumference of the inner ring 19 over the entire circumference.

  A plurality of balls 15 are rotatably incorporated between the two rows of outer raceway grooves 17, 17 and the first and second inner raceway grooves 23, 25, and the inner shaft 14 is mounted on the housing 13. On the other hand, it can rotate around the central axis m.

  The hub unit 10 is mounted on the vehicle by fastening the flange 16 to the knuckle 11 with a bolt 26. Thereafter, the brake rotor 27 and the wheel 12 of the wheel are assembled on the outer side of the hub flange 21. The brake rotor 27 and the wheel 12 are guided by the pilot portion 22 and are mounted coaxially with the central axis m. At this time, the hub bolt 24 penetrates the brake rotor 27 and the wheel 12, and the brake rotor 27 and the wheel 12 are simultaneously fixed to the hub flange 21 by tightening the nut 28.

In the hub unit 10 of the present embodiment, the spline groove 30 is formed on the inner periphery of the inner shaft 14, and the spline shaft of the drive shaft 29 connected to a transaxle (not shown) is inserted in the axial direction. . Thereby, the motive power of the engine is transmitted to the inner shaft 14 and the wheels rotate.
In the present embodiment, a hub unit mounted on a wheel (drive wheel) driven by an engine is illustrated, but a hub unit mounted on a driven wheel may be used. In the case of a driven wheel, it is not necessary to form the spline groove 30 penetrating in the axial direction at the center of the inner shaft 14.

  Next, with reference to FIG. 2, the form of the pilot portion 22, particularly the shape of the first guide surface 40 will be described in detail. FIG. 2 is an enlarged view of a main part in which the first guide surface 40 is enlarged in FIG.

The first guide surface 40 is formed by an outer peripheral surface 42 having a cylindrical shape coaxial with the central axis m, and a protrusion 43 that protrudes radially outward from the center in the axial direction of the outer peripheral surface 42 over the entire circumference. . The protrusion 43 in the axial cross section has a form in which a plurality of straight lines 46, 48 and a plurality of curves 44a, 45, 47 are connected, and points where the straight lines and the curves are connected to each other are indicated by points a to f, respectively. Yes.
In addition, the 2nd guide surface 41 is coaxial with the central axis m, and is formed with the single cylindrical surface.

  The protrusion 43 has a substantially chevron shape in the axial cross section, and has a top 44 near the top of the chevron. Here, the top portion 44 includes a point P where the diameter is maximum and has a predetermined spread on the outer side and the inner side in the axial direction, and is formed by a curve 44a that protrudes radially outward. ing. In the present embodiment, the curve 44 a is a circular arc, and the center Ob of the circular arc is located radially inward from the top 44 and radially outward from the outer peripheral surface 42.

The inner side end portion of the top portion 44 has a first curve 45 (a curve portion between the points a and b) and a first straight line 46 (a straight portion between the points b and c) formed by arcs. And the outer peripheral surface 42. The center Oa of the arc that forms the first curve 45 is located radially outward from the outer peripheral surface 42, and the first curve 45 is convex radially inward (that is, concave radially outward). It has become. The first straight line 46 is a common inscribed line of the arc forming the top 44 and the arc forming the first curve 45.
The point c is a point (first continuous point 49) where the first straight line 46 and the top 44 are connected. At the point c, the angle θ1 (see FIG. 2) formed by the tangent of the arc forming the apex 44 (in the present embodiment, the same straight line as the first straight line 46) and the central axis m is 45 ° or more and 67.67. It is set to 5 ° or less.

At the outer side end portion of the top portion 44, similarly to the inner side, the second curve 47 (which is a curved portion between the point e and the point f) and the second straight line 48 (between the point d and the point e). It is connected to the outer peripheral surface 42 via a straight portion).
The point d is a point where the second straight line 48 and the top 44 are connected (second continuous point 50). At the point d, the angle θ2 formed between the tangent of the arc forming the apex 44 (in this embodiment, the same straight line as the second straight line 48) and the central axis m is set to 45 ° or more and 67.5 ° or less. Has been.

Thus, the tangents of the arcs forming the apex 44 at the positions of the first continuous point 49 and the second continuous point 50 are inclined in opposite directions with respect to the radial direction, and are directed radially outward. Therefore, they are formed so as to approach each other.
Moreover, the protrusion part 43 may not be provided with the first straight line 46 and / or the second straight line 48, and the top part 44 and the first curve 45 and / or the top part 44 and the second curve 47 may be directly connected. . The first straight line 46 and the second straight line 48 need only connect the apex 44 and the first curve 45 and the apex 44 and the second curve 47, respectively. The arc that forms the apex 44, the first curve 45, There is no need to contact any of the second curves 47.

When the wheel 12 and the brake rotor 27 are assembled to the hub unit 10, the brake rotor 27 is fitted to the second guide surface 41 and the wheel 12 is fitted to the first guide surface 40. The radial clearance between the inner periphery of the brake rotor 27 and the second guide surface 41 and between the inner periphery of the wheel 12 and the first guide surface 40 is very small, approximately 0.1 mm to 0.5 mm (diameter dimension). It is. As a result, the brake rotor 27 and the wheel 12 are positioned in the radial direction by the pilot portion 22 and are fixed substantially coaxially with the central axis m.
The wheel 12 is guided in the radial direction by the outer periphery of the protruding portion 43 of the first guide surface 40, and the radial clearance between the inner periphery of the wheel 12 and the first guide surface 40 is defined by the wheel 12. The clearance in the radial direction between the inner periphery and the radially outermost point (point P in FIG. 2) of the protrusion 43 is said.

  Next, the effect of facilitating the removal of the wheel 12 when the pilot portion 22 rusts will be described.

  Since the hub unit 10 is mounted on the vehicle in a state exposed to the atmosphere, when the vehicle travels in rainy weather or the like, the hub unit 10 is wet with rainwater or muddy water (hereinafter referred to as rainwater) accumulated on the road. Rainwater or the like stays between the wheel 12 and the pilot part 22, and the pilot part 22 rusts when left for a long time. At this time, rainwater or the like stays due to the surface tension, and stays more easily as the radial clearance between the wheel 12 and the pilot portion 22 is smaller. When the radial clearance is small, the wheel 12 and the pilot portion 22 are fixed by rust generated in the pilot portion 22.

In this embodiment, the protrusion part 43 is formed in the 1st guide surface 40, and the top part 44 of the protrusion part 43 is formed in the circular arc. For this reason, when the first guide surface 40 is in contact with the inner periphery of the wheel 12, as shown in FIG. 2, the first guide surface 40 is in contact at a point P where the diameter is maximum, and in the circumferential direction of the pilot portion 22, Touching with a line. And the clearance in the radial direction between the inner periphery of the wheel 12 and the first guide surface 40 increases as the distance from the contact point P increases to both axial sides.
Therefore, when rusting occurs on the first guide surface 40, the wheel 12 and the pilot portion 22 are fixed in the region Eo in the vicinity of the point P where the radial clearance is small, and the radial clearance is outside the region Eo in the axial direction. Since it is large, even if the first guide surface 40 is rusted, it is difficult to be fixed.

  Further, the top portion 44 is connected to the first straight line 46 and the second straight line 48 on both sides in the axial direction. In the first straight line 46 and the second straight line 48, the angles θ1 and θ2 formed with the central axis m are both set to 45 ° or more. For this reason, the radial clearance between the first guide surface 40 and the inner peripheral surface of the wheel 12 is further reliably expanded as the distance from the top portion 44 in the axial direction increases in the axial direction. For this reason, in the area | region away from the point P in the axial direction from the point c or the point d, it can prevent more reliably that the wheel 12 and the pilot part 22 adhere.

  The inner diameter of the wheel 12 is slightly larger than the outer diameter of the pilot portion 22. For this reason, between the inner periphery of the wheel 12 and the first guide surface 40, a radial clearance is generated in at least a part of the circumferential direction. Since the radial clearance is increased at the locations where such clearance is generated, the region Eo where the wheel 12 and the first guide surface 40 are fixed further decreases.

  Thus, in the hub unit 10 of the present embodiment, rainwater or the like stays in the gap between the wheel 12 and the pilot portion 22, and even if the first guide surface 40 is rusted, the pilot portion 22, the wheel 12, However, it is only fixed in the region Eo very close to the point P. Therefore, since the area of the region where the first guide surface 40 and the wheel 12 are fixed can be reduced, the fixing force due to rusting can be reduced and the wheel 12 can be easily removed.

Furthermore, in the hub unit 10 of the present embodiment, the center Ob of the arc that forms the top portion 44 is located on the outer side in the radial direction from the outer peripheral surface 42. As a result, the axial dimension of the region Eo is reliably reduced, and the fixing force due to rusting can be reduced. With reference to FIG. 3, the action of reducing the fixing force will be described in detail.
In addition, the center Ob of the arc is the outermost point (point P in the present embodiment) in the radial direction of the top portion 44, the first continuous point 49 (point c in the present embodiment), and the second continuous point 50 ( In this embodiment, when a circle S including the point d) is created, it is defined as the center of the circle S.

  FIG. 3 is a schematic diagram for explaining a range in which the first guide surface 40 and the inner periphery of the wheel 12 are fixed. In FIG. 3, the form of the first guide surface 40 of the present embodiment is indicated by a broken line, and it is assumed that the center Ob of the arc forming the top portion 44 is located radially inward from the outer peripheral surface 42. The shape of the first guide surface 40 (hereinafter referred to as “provisional form”) is indicated by a solid line. In order to distinguish from the present embodiment, the first guide surface of the temporary form will be 40z, the top will be 44z, and the center of the arc forming the top 44z will be described as Oz.

In the temporary form, when the pilot portion 22 is flooded, rainwater or the like stays between the inner periphery of the wheel 12 and the first guide surface 40z, and rust is generated on the first guide surface 40z. For this reason, the wheel 12 and the pilot part 22 adhere in the area | region where the clearance of the radial direction of the inner periphery of the wheel 12 and the 1st guide surface 40z is smaller than the dimension h.
In the temporary form, the center Oz of the arc that forms the top portion 44z is located radially inward from the outer peripheral surface 42. Therefore, the curvature of the arc that forms the top portion 44z is that of the arc that forms the top portion 44 of the present embodiment. Smaller than the curvature. For this reason, in the temporary form, the axial dimension of the region E1 in which the radial clearance between the inner periphery of the wheel 12 and the first guide surface 40z is smaller than the dimension h is the axial dimension of the region Eo in the present embodiment. Larger than As a result, since the area of the region where the wheel 12 and the pilot portion 22 are fixed increases, the fixing force of the wheel 12 increases in the temporary form.

  That is, in the hub unit 10 of the present embodiment, the center Ob of the circle S including the point P, the point c, and the point d is located radially outward from the outer peripheral surface 42. Can be bigger. That is, the diameter dimension of the circle S can be reduced. As a result, the axial dimension of the region Eo in which the radial clearance between the inner periphery of the wheel 12 and the first guide surface 40 is smaller than the dimension h is reliably reduced. As a result, since the area of the region where the wheel 12 and the pilot portion 22 are fixed decreases, the fixing force of the wheel 12 decreases in this embodiment.

  Further, as shown in FIG. 2, the angle θ1 formed by the first straight line 46 and the central axis m and the angle θ2 formed by the second straight line 48 and the central axis m are both set to 67.5 ° or less. ing.

  If it is assumed that the angle θ1 and the angle θ2 are larger than 67.5 °, the width in the axial direction becomes small inward in the radial direction of the protrusion 43. For this reason, the strength of the protrusion 43 is lowered, and the protrusion 43 may be chipped or deformed when the wheel 12 is detached. Moreover, since the volume of the protrusion 43 is reduced by reducing the width in the axial direction, corrosion due to rust easily proceeds, and chipping and deformation may further increase.

  On the other hand, in this embodiment, the axial dimension of the protrusion 43 can be increased by setting the angle θ1 and the angle θ2 to 67.5 ° or less. Thereby, the protrusion 43 can be prevented from being chipped or deformed, and the hub unit 10 can be used over a long period of time.

  Moreover, in the hub unit 10 of this embodiment, the pilot part 22 can be processed into a predetermined shape by machining such as turning. In the conventional hub unit, the pilot portion 22 is generally cylindrical and is machined. Therefore, also in the hub unit 10 of this embodiment, there is no big difference in a process, and it can suppress an increase in manufacturing cost.

  Thus, in the hub unit 10 of the present embodiment, it is possible to prevent the wheel 12 from being fixed due to rusting while suppressing an increase in manufacturing cost. For this reason, it is possible to easily remove the wheel 12 even when it is left for a long time after being exposed to rainwater or the like.

The embodiment of the present invention has been described above. However, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing the above-described embodiment without departing from the spirit thereof.
For example, in this embodiment, although the top part 44 is formed in the circular arc, it is not limited to this, The protrusion part 43 and the wheel 12 should just be formed so that a line contact may be carried out. Therefore, the top 44 may have a curved surface shape other than a circular arc that protrudes radially outward.
In addition, the protrusion 43 may be provided on the second guide surface 41 that positions the brake rotor 27 in the radial direction. Thereby, the brake rotor 27 can be easily removed.
Moreover, in this embodiment, although the wheel 12 of the wheel is being fixed to the inner shaft 14 of the hub unit 10, it is not limited to this. Although not shown, a so-called outer ring rotating hub unit in which the inner shaft 14 is fixed to the knuckle 11 and the housing 13 rotates with respect to the inner shaft 14 may be used. In this case, the pilot portion 22 is formed on the outer side of the housing 13.

10: Hub unit, 11: Knuckle, 12: Wheel, 13: Housing, 14: Inner shaft, 15: Ball, 16: Flange, 20: Shaft portion, 21: Hub flange, 22: Pilot portion, 27: Brake rotor, 40: first guide surface, 41: second guide surface, 42: outer peripheral surface, 43: protrusion, 44: top, 45: first curve, 46: first straight line, 47: second curve, 48: second Straight line, 49: first continuous point, 50: second continuous point

Claims (1)

An inner shaft member having double-row inner raceway grooves on the outer periphery;
An outer ring member having a double row outer raceway groove on the inner periphery;
A plurality of rolling elements disposed so as to be capable of rolling between the inner raceway groove and the outer raceway groove;
One of the inner shaft member and the outer ring member is rotatable around a central axis with respect to the other of the inner shaft member and the outer ring member, and the one member is centered on the central axis. A substantially cylindrical pilot portion that is integrally provided with a wheel bearing,
On the outer peripheral surface of the pilot portion, a protruding portion that protrudes radially outward is provided on a part of the axial direction,
The projecting portion has a top portion that is a radially outwardly convex curve in an axial cross section, and the top portion is a first curve and / or a first convex shape radially inward on one axial side. Connected to the outer peripheral surface via one straight line, and connected to the outer peripheral surface via a second curve and / or a second straight line radially inward on the other side in the axial direction,
The angle formed between the tangent to the top and the central axis at the first continuous point where the top and the first curve or the first straight line are connected is 45 ° or more and 67.5 ° or less,
An angle formed between a tangent line of the top portion and a central axis at a second continuous point where the top portion and the second curve or the second straight line are connected is 45 ° or more and 67.5 ° or less,
For a wheel, wherein the center of a circle including the outermost point in the radial direction of the top, the first continuous point, and the second continuous point is radially outward from the outer peripheral surface. bearing.

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