TECHNICAL FIELD

The present invention relates to a bearing device for vehicle wheel. The present invention particularly relates to a bearing device for vehicle wheel, including an outer member having improved sealing property.

BACKGROUND ART

A conventionally known bearing device for vehicle wheel rotatably supports a vehicle wheel in a suspension device of an automobile or the like, and includes a rotational speed detection device configured to detect the rotational speed of the vehicle wheel. In the bearing device for vehicle wheel, a hub wheel connected with the vehicle wheel is rotatably supported through rolling elements. The rotational speed detection device of the bearing device for vehicle wheel includes an encoder ring on which different magnetic poles are alternately magnetized in the circumferential direction, and a magnetic sensor. In the bearing device for vehicle wheel, the encoder ring is fixed to the hub wheel, and the magnetic sensor is disposed at a part that does not rotate with the hub wheel. In the bearing device for vehicle wheel, the rotational speed of the vehicle wheel connected with the hub wheel can be detected based on the interval of magnetism change when the encoder ring rotating with the hub wheel passes through the vicinity of the magnetic sensor.

In some bearing devices for vehicle wheel, the encoder ring is protected by a cover to prevent false detection caused by damage on the encoder ring of the rotational speed detection device due to a flying rock and the like, and adhesion of mud, magnetic bodies, and the like thereon. For example, the encoder ring is sealed inside an outer ring of the bearing device for vehicle wheel by covering an opening of the outer ring with a non-magnetic cover. Such a configuration is disclosed in, for example, Patent Literature 1.

A bearing device for a vehicle wheel disclosed in Patent Literature 1 includes a protection cover formed in a cylindrical shape and covering a pulser ring (encoder ring), a rotational speed sensor (magnetic sensor), and a sensor cap formed in a cylindrical shape and supporting the rotational speed sensor. The protection cover including a seal member is engaged with an opening of an outer member on the pulser ring side, and the sensor cap is engaged outside of the protection cover. Accordingly, in the bearing device for a vehicle wheel, the protection cover and the sensor cap having high sealing properties not only protect a magnetic pulser ring of a rotational speed detection device from mud, magnetic bodies, and the like, but also reduce damage due to a flying rock and the like. In the bearing device for a vehicle wheel, a part engaged with the protection cover, a part in contact with the seal member of the protection cover, and a part engaged with the sensor cap are formed on an inner periphery of the opening of the outer member on the pulser ring side, and have larger inner diameters in the stated order. Accordingly, a plurality of steps are formed on the inner periphery of the opening of the outer member on the pulser ring side. With this configuration, the bearing device for a vehicle wheel needs to have a complicated fabrication on the inner periphery of the opening of the outer member to avoid damage on the seal member due to contact with the step when the protection cover is attached to the outer member.

CITATIONS LIST

Patent Literature

Patent Literature 1: JP-A 2015-68454 Gazette

SUMMARY OF INVENTION

Technical Problems

The present invention is intended to solve the above-described problem and provide a bearing device for a vehicle wheel capable of maintaining the sealing property of a protection cover by preventing damage on a seal member of the protection cover without a complicated fabrication at an inner side opening of an outer member.

Solutions to Problems

A bearing device for vehicle wheel according to the present invention includes: an outer member having an inner periphery on which outside rolling surfaces in a plurality of lines are integrally formed; an inner member including a hub wheel and at least one inner ring and having an outer periphery on which inside rolling surfaces in a plurality of lines are formed facing to the outside rolling surfaces in the plurality of lines, the hub wheel integrally including a vehicle wheel attachment flange to which a vehicle wheel is attached at one end part and including a small-diameter stepped part extending in an axial direction and formed on an outer periphery at the other end part, the at least one inner ring being fitted by pressing to the small-diameter stepped part; rolling elements arranged in a plurality of lines and housed in a freely rollable manner between each inside rolling surface and the corresponding outside rolling surface; a protection cover formed in a cylindrical shape and engaged with an inner periphery of an inner side opening of the outer member and having an outer peripheral surface on which a circular ring seal member is provided; and a sensor holder formed in a cylindrical shape and engaged outside of the protection cover on the inner periphery of the inner side opening of the outer member. A sensor holder engagement part engaged with the sensor holder, a seal part in contact with the seal member of the protection cover, and a protection cover engagement part engaged with the protection cover are formed on the inner periphery of the inner side opening of the outer member sequentially from an inner side end to an outer side in the axial direction. An inner diameter of the seal part is larger than an inner diameter of the protection cover engagement part and equal to an inner diameter of the sensor holder engagement part. The seal part is adjacent to the sensor holder engagement part.

In the bearing device for vehicle wheel according to the present invention, it is preferable that: the outer peripheral surface of the protection cover includes a large-diameter part, a tapered part connected with the large-diameter part, and a small-diameter part connected with the tapered part; the seal member is provided between the tapered part and the small-diameter part; an outer diameter of the seal member is larger than the inner diameter of the seal part; and the large-diameter part is engaged with the protection cover engagement part.

In the bearing device for vehicle wheel according to the present invention, it is preferable that the seal member includes an annular protrusion part protruding outward in a radial direction.

In the bearing device for vehicle wheel according to the present invention, it is preferable that the annular protrusion part is formed in a lip shape.

In the bearing device for vehicle wheel according to the present invention, it is preferable that: a flange part is formed at an intermediate part on an outer peripheral surface of the sensor holder; the outer peripheral surface is engaged with the sensor holder engagement part; and the sensor holder is engaged at a position determined when the flange part contacts with an end face of the outer member.

Advantageous Effects of Invention

In a bearing device for a vehicle wheel according to the present invention, no step exists in a range through which a seal member of a protection cover passes on an inner peripheral surface of an inner side opening of an outer member. Accordingly, the sealing property of the protection cover can be maintained by preventing damage on the seal member without a complicated fabrication at the inner side opening of the outer member. Moreover, the diameter of a sensor holder engagement part of the inner side opening is reduced toward inside in the radial direction to avoid a step so that the inner side opening has a small outer diameter. With this configuration, the outer member has a light weight.

In the bearing device for a vehicle wheel according to the present invention, a large-diameter part and a small-diameter part of the protection cover are coupled with each other through a tapered part to reduce an increase of the stiffness of the large-diameter part on a small-diameter side, and thus the shape of the large-diameter part is likely to fit an inside engagement surface of the outer member. Accordingly, the sealing property of the protection cover can be maintained by preventing damage on the seal member without a complicated fabrication at the inner side opening of the outer member.

In the bearing device for a vehicle wheel according to the present invention, reduced frictional resistance is generated when the seal member of the protection cover slides on a seal part and the sensor holder engagement part of the inner side opening of the outer member. Accordingly, the sealing property of the protection cover can be maintained by preventing damage on the seal member without a complicated fabrication at the inner side opening of the outer member.

In the bearing device for a vehicle wheel according to the present invention, no step needs to be provided on an inner periphery of the outer member to determine an engagement position of a sensor holder. Accordingly, the sealing property of the protection cover can be maintained by preventing damage on the seal member without a complicated fabrication at the inner side opening of the outer member.

