JP2009243643A - Rolling bearing for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing for a wheel capable of improving durability in comparison with when using a ball as a rolling element, and capable of improving fuel consumption of an automobile in comparison with when using a tapered roller as the rolling element. <P>SOLUTION: The rolling bearing for a wheel is equipped with an outer ring 11 fixed to a vehicle body, an inner ring 12 to be attached with the wheel, and rolling elements 15 arranged in plural rows between the outer ring 11 and the inner ring 12, and the rolling elements 15 are arranged facing outward. The rolling element 15 has a rolling contact surface 15a contacting and rolling on raceway surfaces 11u, 12u or raceway surfaces 11s, 12s respectively formed on the outer ring 11 and the inner ring 12. In a plane 15B including axes 15A of the rolling elements 15, the rolling contact surfaces 15a are formed like arcs, and in the rolling contact surfaces 15a in the plane 15B, the rolling elements 15 are formed like barrels by carrying out axisymmetrical forming using an axis 15C passing through a center point of the rolling element 15 and orthogonal to the axis 15A of the rolling element 15 as a symmetry axis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wheel rolling bearing mainly used in an automobile.

  Generally, an automobile includes a wheel rolling bearing for rotatably supporting the wheel. A wheel rolling bearing includes an outer ring fixed to a vehicle body, an inner ring to which the wheel is attached, and rolling elements arranged in a double row between the outer ring and the inner ring, and the rolling elements are arranged outward. The double-row angular contact ball bearing is configured (see, for example, Patent Document 1).

  More specifically, for example, as shown in FIG. 4, the wheel rolling bearing 101 includes an outer ring 111 fixed to the vehicle body, an inner ring 112 to which the wheel is attached, and a double row between the outer ring 111 and the inner ring 112. And the rolling elements 115 are disposed outward. Note that “the rolling elements 115 are disposed outward” means that an action point distance on the outer ring side (hereinafter referred to as “action point distance D1”) is an action point distance on the inner ring side (hereinafter referred to as “action point”). This means that the rolling element 115 is in contact with the raceway surfaces 111u, 111s, 112u, and 112s formed on the outer ring 111 and the inner ring 112 so as to be shorter than the distance D2. Further, the “action point distance D1” means an action point Gu of a force acting on the rolling elements 115u in one row by the outer ring 111 on the raceway surface 111u in a direction parallel to the central axis A of the wheel rolling bearing 101. It means the length between the outer ring 111 on the raceway surface 111s and the point Gs of the force acting on the other row of rolling elements 115s. Further, the “action point distance D2” refers to the action point Nu of the force acting on the rolling elements 115u in one row by the inner ring 112 on the raceway surface 112u in the direction parallel to the center axis A of the wheel rolling bearing 101, and the raceway. The length between the inner ring 112 on the surface 112s and the point of action Ns of the force acting on the other row of rolling elements 115s. When the action point distance D1 is shorter than the action point distance D2, the stiffness against the moment load (so-called moment) is greater than when the action point distance D1 is equal to the action point distance D2 or the action point distance D1 is longer than the action point distance D2. (Rigidity) can be increased. The angle α between the line passing through the point of action Gu and the point of action Nu, and the line passing through the point of action Gs and the point of action Ns perpendicular to the central axis A is called the contact angle, and is an important factor that determines the composition of the bearing. It is managed as.

Here, in the wheel rolling bearing, when the rolling elements are disposed outward as described above, unnecessary torque is applied to the shaft supported by the wheel rolling bearing by reducing the rolling resistance of the rolling elements. In order to reduce the occurrence of this and improve the fuel efficiency of automobiles, it is known to use balls instead of tapered rollers as rolling elements. In other words, when a tapered roller is used as the rolling element, it is necessary to form a flange in sliding contact with the end face of the tapered roller on the outer ring or the inner ring in order to support thrust in a direction parallel to the central axis of the tapered roller. Therefore, since the rolling resistance of the rolling element is increased by providing a flange that is in sliding contact with the end surface of the tapered roller that is the rolling element, from the viewpoint of improving the fuel consumption of the automobile, as shown in FIG. A spherical rolling element 115 (that is, a ball) that does not require the collar is used.
JP 2000-168307 A

  However, when the spherical rolling element 115 is used (that is, when a ball is used as the rolling element), the rolling resistance of the rolling element 115 can be reduced, but the rolling element 115 is formed on each of the outer ring 111 and the inner ring 112. The area of the contact surface with which the raceway surfaces 111u, 111s, 112u, and 112s come into contact is small, and the durability of the wheel rolling bearing 101 is low. In order to increase the area of the contact surface and improve the durability of the wheel rolling bearing 101, a tapered roller can be used as a rolling element. The rolling resistance of the moving body increases, unnecessary torque is generated on the shaft supported by the wheel rolling bearing 101, and the fuel consumption of the automobile deteriorates. That is, there is a problem that it is difficult to achieve both the improvement of the durability of the wheel rolling bearing 101 and the improvement of the fuel consumption of the automobile.

  The present invention has been made in view of such circumstances, and its purpose is to improve durability compared to the case of using balls as rolling elements, and the case of using tapered rollers as rolling elements. In comparison, an object of the present invention is to provide a wheel rolling bearing capable of improving the fuel efficiency of an automobile.

  The invention according to claim 1 includes an outer ring fixed to the vehicle body, an inner ring to which the wheel is attached, and rolling elements arranged in a double row between the outer ring and the inner ring, and the rolling element faces outward. A rolling bearing for a wheel, wherein the rolling element has a rolling surface that rolls in contact with a raceway surface formed on each of the outer ring and the inner ring, and the rolling surface is the center of the rolling element. In the plane including the axis, it is formed in an arc shape, and the rolling surface is formed in line symmetry with the axis passing through the center point of the rolling element and orthogonal to the central axis of the rolling element as the symmetry axis. Thus, the rolling element is formed in a barrel shape.

  According to this configuration, the rolling surface of the rolling element formed in a barrel shape is formed in an arc shape on a plane including the central axis of the rolling element. For this reason, for example, while making the contact surface where the rolling element and the raceway surface formed on each of the outer ring and the inner ring contact approximately the same size as the contact surface in the case of using a ball as the rolling element, The volume can be reduced. Therefore, by reducing the volume of the rolling elements, the number of rolling elements for one row can be increased, and the total area of the contact surface can be increased. As a result, compared with the case where balls are used as rolling elements, the load generated in the wheel rolling bearing is dispersed without changing the overall size of the wheel rolling bearing, thereby improving the durability of the wheel rolling bearing. Can be achieved. Further, according to the above configuration, the rolling surface of the rolling element formed in a barrel shape has an axis passing through the center point of the rolling element and orthogonal to the central axis of the rolling element in a plane including the central axis of the rolling element. It is formed in line symmetry as a symmetry axis. For this reason, unlike the case where the tapered roller is used as the rolling element, the rolling element can be brought into contact with the raceway surfaces formed on the outer ring and the inner ring on the symmetry axis passing through the center point of the rolling element. Therefore, since the line of force acting on the rolling element by the outer ring and the line of force acting on the rolling element by the inner ring are on the above-mentioned symmetry axis, thrust is generated in a direction parallel to the central axis of the rolling element. It is not necessary to provide a collar that is in sliding contact with the end face of the rolling element. As a result, the rolling resistance of the rolling element can be reduced compared to the case where a tapered roller is used as the rolling element, and for example, the generation of unnecessary torque on the shaft supported by the wheel rolling bearing is suppressed. This can improve the fuel efficiency of automobiles.

  Invention of Claim 2 is a rolling bearing for wheels of Claim 1, Comprising: In the said plane, the track surface formed in each of an outer ring | wheel and an inner ring | wheel has a curvature larger than the curvature radius of a rolling surface. It has a radius.

  According to this configuration, compared with the case where the radius of curvature of the raceway surface and the rolling surface is the same in the plane including the central axis of the rolling element, the contact between the rolling element and the raceway surface formed on each of the outer ring and the inner ring. The area can be reduced. Therefore, the rolling resistance of the rolling element can be further reduced.

  According to the present invention, compared to the case where balls are used as rolling elements, the durability of the rolling bearing for wheels can be improved without changing the overall size of the rolling bearing for wheels. Compared to the case where rollers are used, the rolling resistance of the rolling elements can be reduced to improve the fuel efficiency of the automobile.

  Embodiments according to the present invention will be described below with reference to FIGS. The arrows U and S in the figure indicate the axial direction of the wheel rolling bearing, and the arrows U and S indicate the vehicle body side direction and the wheel side direction, respectively.

  The wheel rolling bearing according to this embodiment is used for a driven wheel as a hub unit for an automobile. More specifically, as shown in FIGS. 1 and 2, the wheel rolling bearing 1 is provided between an outer ring 11 fixed to a vehicle body (not shown) and an inner ring 12 to which a wheel (not shown) is attached. This is a bearing for rotatably supporting the wheel by interposing the double row rolling elements 15.

  A flange portion 11a through which a bolt (not shown) for fixing the outer ring 11 to the vehicle body is integrally formed is formed integrally with the outer periphery 11A of the outer ring 11 formed in a cylindrical shape. , Two rows (that is, an inner row and an outer row) of raceway surfaces 11u and 11s are formed in an annular shape.

  An inner ring 12 is provided inside the outer ring 11 via a rolling element 15. In the present embodiment, the inner ring 12 is an inner ring provided separately from the hub shaft 13 and the hub shaft 13 in which a hub attached to the center of the wheel and a rotating shaft fixed to the hub are integrated. The member 14 is comprised.

  A flange portion 13a into which a bolt 6 for attaching the wheel to the hub shaft 13 is inserted is formed on the wheel side outer periphery 13A of the hub shaft 13, and the hub shaft 13 facing the raceway surface 11s on the wheel side is formed. A row of raceway surfaces 12s is formed in an annular shape on the outer periphery 13B.

  Further, an annular inner ring member 14 is fitted to the outer periphery 13C of the hub shaft 13 facing the raceway surface 11u on the vehicle body side. On the outer periphery 14A of the inner ring member 14, a row of raceway surfaces 12u are formed in an annular shape.

  As shown in FIG. 1, the inner ring member 14 fitted to the hub shaft 13 is in contact with a step 13 b formed on the hub shaft 13, so that the inner ring member 14 formed on the hub shaft 13 on the vehicle body side end portion 13 </ b> D is formed. The inner ring member 14 is fixed to the hub shaft 13 by screwing the nut 7 into the screw portion 13c. Accordingly, the inner ring 12 (that is, the hub shaft 13 and the inner ring member 14 constituting the inner ring 12) rotates together with the wheels attached to the inner ring 12.

  The double-row (two-row) rolling elements 15 interposed between the outer ring 11 and the inner ring 12 have raceway surfaces 11u and 12u formed on the outer ring 11 and the inner ring 12, respectively, as shown in FIGS. Alternatively, a rolling surface 15a that rolls in contact with the raceway surfaces 11s and 12s and an end surface 15b that does not contact the raceway surfaces 11u, 11s, 12u, and 12s are formed.

  Of the double-row rolling elements 15, one row of rolling elements 15 u provided on the vehicle body side comes into contact with the raceway surfaces 11 u and 12 u formed on the outer ring 11 and the inner ring member 14, respectively. Among the rolling elements 15, another row of rolling elements 15 s provided on the wheel side is in contact with the raceway surfaces 11 s and 12 s formed on the outer ring 11 and the hub shaft 13, respectively. Therefore, when the inner ring 12 rotates, one row of rolling elements 15u rolls on the raceway surface 11u and the raceway surface 12u, and another row of rolling elements 15s moves on the raceway surface 11s and the raceway surface 12s. Roll.

  And in this embodiment, the rolling element 15 is arrange | positioned outward. More specifically, as shown in FIG. 2, the rolling elements 15 are formed on the raceway surfaces 11u, 11s, and 11b formed on the outer ring 11 and the inner ring 12 so that the action point distance D1 is shorter than the action point distance D2. 12u and 12s are in contact. Here, the “action point distance D1” is 1 by the outer ring 11 on the raceway surface 11u in a direction parallel to the central axis A of the wheel rolling bearing 1 (direction indicated by an arrow B in FIG. 2). This is the length between the application point Gu of the force Fu acting on the rolling elements 15u in the row and the action point Gs of the force Fs acting on the other rolling elements 15s in the other row by the outer ring 11 on the raceway surface 11s. Further, the “action point distance D2” is an action point Nu of the force Eu acting on the rolling elements 15u in one row by the inner ring 12 on the raceway surface 12u in a direction parallel to the central axis A of the wheel rolling bearing 1. , The length between the inner ring 12 on the raceway surface 12s and the application point Ns of the force Es acting on the other row of rolling elements 15s.

  Therefore, since the action point distance D1 is shorter than the action point distance D2, the action point distance D1 is equal to the action point distance D2 or the action point distance D1 is longer than the action point distance D2. The action point distance D is large. As used herein, “the working point distance D of the wheel rolling bearing 1” means the working points S1 and S2 (the line of action L1 of the force acting on the rolling elements 15u in one row by the outer ring 11). Each of the lines of action L2 of the force acting on the other one row of rolling elements 15s by the outer ring 11 is a length between the points intersecting the central axis A of the wheel rolling bearing 1). Therefore, since the action point distance D of the wheel rolling bearing 1 is larger than when the action point distance D1 is equal to the action point distance D2 or the action point distance D1 is longer than the action point distance D2, the wheel rolling bearing 1 High rigidity against moment load.

  As described above, the wheel rolling bearing 1 according to the present embodiment includes the outer ring 11 fixed to the vehicle body, the inner ring 12 to which the wheel is attached, and the rolling elements disposed in a double row between the outer ring 11 and the inner ring 12. 15 and the rolling element 15 is arranged outward.

  Here, in the present embodiment, as shown in FIGS. 2 and 3, the rolling surface 15a is formed in an arc shape on the plane 15B including the central axis 15A of the rolling element 15, and the rolling surface 15a. However, it is formed in line symmetry with an axis 15C passing through the center point C of the rolling element 15 and orthogonal to the central axis 15A of the rolling element 15 as an axis of symmetry. And it is characterized by the rolling element 15 being formed in the barrel shape by being formed as mentioned above. In FIG. 2, C <b> 1 is the center of a circle having the rolling surface 15 a as a part of the circumference on a plane 15 </ b> B including the center axis 15 </ b> A of the rolling element 15.

  According to such a configuration, the rolling surface 15a of the rolling element 15 formed in a barrel shape is formed in an arc shape on the plane 15B including the central axis 15A of the rolling element 15. For this reason, for example, the contact surface where the rolling element 15 and the raceway surfaces 11u, 12u, 11s, and 12s formed on each of the outer ring 11 and the inner ring 12 are in contact with each other is the contact surface described above when using balls as the rolling elements. And the size of the rolling element 15 can be reduced. Therefore, by reducing the size of the rolling elements 15, the number of rolling elements 15 for one row can be increased, and the total area of the contact surface can be increased.

  Furthermore, according to the above configuration, the rolling surface 15a of the rolling element 15 formed in a barrel shape passes through the center point C of the rolling element 15 on the plane 15B including the central axis 15A of the rolling element 15 and the rolling element 15. The axis 15C orthogonal to the central axis 15A is symmetrical with respect to the axis of symmetry. For this reason, unlike the case where the tapered roller is used as the rolling element 15, the rolling element 15 is formed on each of the outer ring 11 and the inner ring 12 on a straight line passing through the center point C of the rolling element 15 (that is, on the shaft 15C). The track surfaces 11u, 12u, 11s, and 12s can be brought into contact with each other. More specifically, as shown in FIG. 2, one row of rolling elements 15u contacts the raceway surfaces 11u and 12u formed on the outer ring 11 and the inner ring 12 on the axis of symmetry (on the axis 15C). Another row of rolling elements 15s can be brought into contact with the raceway surfaces 11s and 12s formed on the outer ring 11 and the inner ring 12 on the axis of symmetry. Accordingly, the line of action of the force Fu acting on the one row of rolling elements 15u by the outer ring 11 and the line of action of the force Eu acting on the one row of rolling elements 15u by the inner ring 12 are on the axis of symmetry. 15 thrusts in a direction parallel to the central axis 15A are unlikely to occur in one row of rolling elements 15u. Similarly, the line of action of the force Fs acting on the other one row of rolling elements 15s by the outer ring 11 and the line of action of the force Es acting on the other row of rolling elements 15s by the inner ring 12 are on the symmetry axis. Therefore, the thrust F in the direction parallel to the central axis 15A of the rolling elements 15 is unlikely to be generated in the other one row of rolling elements 15s. As a result, unlike the case of using a tapered roller as the rolling element, there is no need to provide a collar that is in sliding contact with the end surface 15b of the rolling element 15.

  Further, in the present embodiment, as shown in FIG. 2, on the plane 15B including the central axis 15A of the rolling element 15, the raceway surfaces 11u and 12u formed on the outer ring 11 and the inner ring 12 are respectively rolling surfaces 15a. The curvature radius R2 is larger than the curvature radius R1. Further, in the plane 15B including the central axis 15A of the rolling element 15, the raceway surfaces 11s and 12s formed on the outer ring 11 and the inner ring 12 similarly have a curvature radius R2 larger than the curvature radius R1 of the rolling surface 15a. Have. In FIG. 2, C2 is the center of a circle having any one of the raceway surfaces 11u, 12u, 11s, and 12s as a part of the circumference in a plane 15B including the center axis 15A of the rolling element 15.

  With this configuration, the radius of curvature R2 of the raceway surfaces 11u, 11s, 12u, and 12s is larger than the radius of curvature R1 of the rolling surface 15a, so that the rolling radius R1 and the radius of curvature R2 are the same as when the radius of curvature R1 is the same. The contact area between the moving body 15 and the raceway surfaces 11u, 11s, 12u, 12s formed on each of the outer ring 11 and the inner ring 12 can be reduced.

According to the wheel rolling bearing 1 of the present embodiment, the following effects can be obtained.
(1) The rolling element 15 has a raceway surface 15a that rolls in contact with the raceway surfaces 11u, 12u or raceway surfaces 11s, 12s formed on the outer ring 11 and the inner ring 12, respectively. The rolling surface 15a is formed in an arc shape in the plane 15B including the central axis 15A of the rolling element 15, and the rolling surface 15a passes through the center point C of the rolling element 15 in the plane 15B. The moving body 15 is formed in line symmetry with an axis 15C orthogonal to the central axis 15A of the moving body 15 as an axis of symmetry. Since the rolling element 15 is formed in a barrel shape by being formed as described above, the total area of the contact surface can be increased as described above. As a result, compared with the case where balls are used as rolling elements, the load generated in the wheel rolling bearing 1 is dispersed without changing the overall size of the wheel rolling bearing 1, so that the durability of the wheel rolling bearing 1 is improved. It is possible to improve the performance. In addition, as described above, the thrust F in the direction parallel to the central axis 15A of the rolling element 15 is not easily generated, and it is not necessary to provide a collar that is in sliding contact with the end surface 15b of the rolling element 15. As a result, the rolling resistance of the rolling element 15 can be reduced as compared with the case where a tapered roller is used as the rolling element, and unnecessary torque is generated in the hub shaft 13 supported by the wheel rolling bearing 1. It is possible to improve the fuel efficiency of the automobile by suppressing it.

  (2) In the plane 15B including the central axis 15A of the rolling element 15, the raceway surfaces 11u, 11s, 12u, 12s formed on each of the outer ring 11 and the inner ring 12 have a curvature larger than the curvature radius R1 of the rolling surface 15a. It has a radius R2. For this reason, the contact area between the rolling elements 15 and the raceways 11u, 11s, 12u, 12s formed on the outer ring 11 and the inner ring 12 can be reduced, and the rolling resistance of the rolling elements 15 can be further reduced, It is possible to improve the fuel consumption of an automobile equipped with the wheel rolling bearing 1.

  In addition, this invention is not limited to the said embodiment, A various design change is possible based on the meaning of this invention, and they are not excluded from the scope of the present invention. For example, you may change the said embodiment as follows.

  In the above embodiment, in the plane 15B including the central axis 15A of the rolling element 15, the raceway surfaces 11u, 11s, 12u, 12s formed on each of the outer ring 11 and the inner ring 12 have a radius of curvature R1 of the rolling surface 15a. However, the curvature radius R1 and the curvature radius R2 may be the same. Even if comprised in this way, the effect of said (1) can be acquired.

  In the above embodiment, the double-row rolling elements 15 (that is, both the one-row rolling elements 15u provided on the vehicle body side and the other one-row rolling elements 15s provided on the wheel side) are in a barrel shape. Although formed, only one of the one row of rolling elements 15u and the other row of rolling elements 15s may be formed in a barrel shape.

  In the above embodiment, the inner ring member 14 is fixed to the hub shaft 13 with the nut 7, but the screw portion 13 c is not provided at the vehicle body side end portion 13 D of the hub shaft 13, and the nut 7 is used. Instead, the inner ring member 14 may be fixed to the hub shaft 13. For example, the vehicle body side end portion 13D of the hub shaft 13 is formed in a cylindrical shape, and the cylindrical vehicle body side end portion 13D is radially outward (that is, a direction perpendicular to the axial direction of the wheel rolling bearing 1). By expanding the diameter, the vehicle body side end portion 13D of the hub shaft 13 may be caulked to the end surface of the inner ring member 14, and the inner ring member 14 may be fixed to the hub shaft 13.

The schematic block diagram which shows the rolling bearing for wheels which concerns on embodiment of this invention. The expanded sectional view of the part which the arrow S in FIG. 1 shows. The perspective view which shows the rolling element of the rolling bearing for wheels which concerns on embodiment of this invention. The schematic block diagram which shows the conventional rolling bearing for wheels.

Explanation of symbols

  A: Center axis of rolling bearing for wheel, C: Center point of rolling element, R1, R2 ... Radius of curvature, 1 ... Rolling bearing for wheel, 11 ... Outer ring, 11u, 11s ... Track surface, 12 ... Inner ring, 12u, 12s ... raceway surface, 13 ... hub shaft, 14 ... inner ring member, 15 ... rolling element, 15a ... rolling surface, 15b ... end face, 15A ... center axis of rolling element, 15B ... plane including the central axis of rolling element, 15C ... An axis that passes through the center of the rolling element and is orthogonal to the central axis of the rolling element.

Claims (2)

A wheel having an outer ring fixed to a vehicle body, an inner ring to which a wheel is attached, and rolling elements disposed in a double row between the outer ring and the inner ring, wherein the rolling element is disposed outward. Rolling bearing for
The rolling element has a rolling surface that rolls in contact with a raceway surface formed on each of the outer ring and the inner ring,
The rolling surface is formed in an arc shape in a plane including the central axis of the rolling element, and the rolling surface passes through a central point of the rolling element and is in the central axis of the rolling element in the plane. A rolling bearing for a wheel, wherein the rolling element is formed in a barrel shape by being formed symmetrically about an orthogonal axis as a symmetry axis.   2. The wheel rolling bearing according to claim 1, wherein the raceway surface formed on each of the outer ring and the inner ring has a radius of curvature larger than a radius of curvature of the rolling surface in the plane.

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