Structure for attaching a wheel speed sensor in motorcycle

A motorcycle includes radial mount type disk brakes, a brake caliper of the disk brake is mounted on a lower portion of a front fork, which pivotably supports a front wheel, the wheel speed sensor is attached to a mounting boss disposed at the lower portion of one leg of the front fork so as to dispose the wheel speed sensor between the brake caliper and the wheel axle. This mounting location is desirable in terms of lowering costs and ease of brake maintenance.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority under 35 USC 119 based on Japanese patent application No. 2004-085371, filed on Mar. 23, 2004. The subject matter of this priority document is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a motorcycle having disc brakes in which a brake caliper of a disk brake is mounted on a mounting boss disposed at a lower portion of a front fork. The mounting direction of the brake caliper is arranged along a radial direction of the front wheel. The present invention relates more particularly to an improvement in a structure of attaching a wheel speed sensor for detecting a speed of a front wheel.

2. Description of the Background Art

A motorcycle in which a wheel speed sensor detecting a speed of a front wheel is attached to a lower portion of a front fork is already known. Such a wheel speed sensor is disclosed in Japanese Examined Utility Model Publication No. 17609/1995. Further, as disclosed in Japanese Unexamined Patent Publication No. 12149/1995, there is known a disk brake of radial mount type used, for instance, with a racing motorcycle. In this document, a mounting direction of a brake caliper is set to be along a radial direction of the wheel to enhance the ease of attaching and detaching the brake caliper.

In a motorcycle in which the brake caliper of the disk brake of radial mount type is attached to the lower portion of the front fork, it is desirable to dispose a wheel speed sensor at a position that does not inhibit a replacement of the brake caliper. Further, the position of the wheel speed sensor is advantageous in terms of the cost and maintenance of the components.

The present invention has been developed based on the foregoing, and an object of the present invention is to provide an improved structure for attaching a wheel speed sensor in a motorcycle in which a brake caliper of a disk brake of radial mount type is attached to a lower portion of a front fork. Specifically, a structure is provided in which the wheel speed sensor is disposed at an advantageous position in terms of the cost and maintenance.

SUMMARY OF THE INVENTION

To attain the above object, according to a first aspect of the invention there is provided a structure for attaching a wheel speed sensor to a wheel in a motorcycle. The motorcycle includes a disk brake for braking the front wheel, and the front wheel is pivotably supported on a front fork. In the inventive structure, a brake caliper of the disk brake is mounted on a mounting boss disposed at a lower portion of a front fork, the brake caliper is mounted so as to have a mounting direction aligned with a radial direction of the front wheel, and a wheel speed sensor is attached to the mounting boss.

According to a second aspect of the invention, the mounting boss in the above described structure is formed integrally with, and continuously from, an axle supporting portion which is formed at a lower end of the front fork to pivotably support the front wheel.

According to a third aspect of the invention, the above described structure further includes another mounting boss having the brake caliper mounted thereto, said mounting bosses are separated in a vertical direction and formed at a lower portion of the front fork. The wheel speed sensor is attached to an under surface of a lower one of the mounting bosses.

According to the first aspect of the invention, the wheel speed sensor is attached to the mounting boss, which is disposed at the lower portion of the front fork. The mounting boss is used to attach the radial mount type disc brake to the wheel of the motorcycle. Thus, it is possible to dispose the wheel speed sensor at a position which permits replacement of the brake caliper without interference with the wheel speed sensor. In addition, it is possible to omit an exclusive, or dedicated, mounting structure for the wheel speed sensor, such as a boss, a stay, or the like. These features facilitate the maintenance of the disk brake and reduce overall costs.

According to the second aspect of the invention, exclusive, or dedicated, members to which the brake caliper of the disk brake and the wheel speed sensor are attached are omitted, thereby reducing the number of members.

According to the third aspect of the invention, the wheel speed sensor is disposed so as to efficiently utilize a space below the mounting boss.

Modes for carrying out the present invention are explained below by reference to an embodiment of the present invention shown in the attached drawings. The above-mentioned object, other objects, characteristics and advantages of the present invention will become apparent form the detailed description of the embodiment of the invention presented below in conjunction with the attached drawings.

DETAILED DESCRIPTION OF THE INVENTION

A present embodiment of the invention will now be described as shown in the accompanying drawings.

Referring first toFIGS. 1 and 2, a front fork5of the motorcycle has a pair of legs6,7disposed on opposed sides of a front wheel WF. Each of the legs6,7has an axle supporting portion6a,7aat its lower end. An axle collar8, and an axle9disposed through the axle collar8, are fixedly disposed between the axle supporting portions6a,7a. The axial positions of the axle collar8and axle9are fixed.

The front wheel WF comprises a cylindrical hub12coaxially enclosing the axle collar8. A pair of ball bearings10,11is interposed between the hub12and the axle collar8. A rim13coaxially surrounds the hub12, and a plurality of spokes14integrally connects the hub12and the rim13. A tire15is placed on the rim13so as to surround the rim13.

A pair of mounting bosses16,17are formed integrally with and continuously from the axle supporting portion6a,7aso as to be positioned at a lower portion of each of the legs6,7of the front fork5. Mounting bosses16,17extend in parallel and are separated in a vertical direction. Respective brake calipers19of a pair of disk brakes18for braking the front wheel WF are mounted on respective pairs of the mounting bosses16,17. The respective brake calipers19are mounted in a mounting direction20(see arrow inFIG. 1) corresponding to and aligned with a radial direction of the front wheel WF.

Referring also toFIG. 3, each of the disk brakes18comprises a brake disk22attached to an end of the hub12using a plurality of screw members21. Each of the disk brake18also includes a pair of friction pads23,23disposed on opposite sides of the brake disk22, and the brake caliper19extending from one side of the disk brake22to the other side thereof over a circumference of the disk brake22to support the friction pads23,23. The brake caliper19comprises an acting portion24and a reacting portion25that are connected to each other.

In each of the acting portion24and the reacting portion25, there is slidably fitted a piston26. The metal backings23a,23aof the respective friction pads23,23disposed on opposed sides of the brake disk22are pushed by the respective pistons26and thereby brought into frictional contact with the brake disk22.

The disk brake18, constructed as described above, is of radial mount type. The acting portion24of its brake caliper19is fastened to the bosses16,17with a pair of mounting bolts27,28. Each mounting bolt27,28has an axis along a radial direction of the front wheel WF.

A pulser ring30, made of a magnetic metal, is held in contact with a central portion of an outer surface of the brake disk22of the disk brake18. The pulser ring30is disposed on the right side of the front wheel WF. The pulser ring30is integrally fastened to a left side end of the hub12jointly with the brake disk22, using the screw members21. As a result, the pulser ring30rotates with the front wheel WF.

A multiplicity of protrusions31are formed at an outer circumference of an outer side of the pulser ring30. The protrusions are provided with an equal spacing therebetween in the circumferential direction. A wheel speed sensor32is fastened to a support plate33with bolts34so as to oppose to the protrusions31, and to be spaced apart from the protrusions by a small distance. The wheel speed sensor is a magnetic proximity sensor for detecting a speed of the front wheel WF by detecting the protrusions31.

The support plate33is used to mount the wheel speed sensor to the mounting bosses16,17. The support plate33is substantially L-shaped and fastened with bolts35to the under surface of the mounting boss17. Note that mounting boss17is the lower one of the pair of mounting bosses16,17formed at the right one6of the legs6,7of the front fork5. That is, the wheel speed sensor32is disposed at the lower portion of the front fork5and on the right side of the front wheel WF, and is attached, via the support plate33, to the under surface of the lower one17of the mounting bosses16,17that are disposed integrally with the lower portion of the right side of the front fork5.

The upper side of the front wheel WF is covered by a front fender36. A pair of attaching plates37,38, each having a protruding shape, are formed integrally with a lower part of each of the legs6,7of the front fork5. The front fender36is fastened to the two pairs of attaching plates37,38.

Operation of this embodiment will now be described. The brake calipers19of the disk brakes18for braking the front wheel WF are respectively mounted on the mounting bosses16,17at the lower portions of the respective legs6,7of the front fork5. The front fork5pivotably supports the front wheel WF, and legs6,7are disposed on opposed sides of the front wheel WF. The brake calipers19are mounted on the mounting bosses16,17, so as to be oriented in a mounting direction20aligned with a radial direction of the front wheel WF. The wheel speed sensor32is attached via the support plate33to the mounting boss17disposed in the leg6of the right side. The wheel speed sensor32is positioned generally between the brake calipers19and the axle9.

The wheel speed sensor32is attached to the mounting boss17. The mounting boss17is disposed at the lower portion of the front fork5in order to mount the brake caliper19of the disk brake18of radial mount type thereon. Therefore, the wheel speed sensor32can be disposed at a position which does not interfere with replacement of the brake caliper19. In addition, it is unnecessary to provide a dedicated mounting member for the wheel speed sensor32such as a boss, stay, or the like. These features facilitate the maintenance of the disk brake18and reduce manufacturing and maintenance costs.

The axle supporting portions6a,7aare formed at the lower ends of the legs6,7of the front fork5. The mounting bosses16,17are formed integrally with, and continuously from, the respective axle supporting portions6a,7a. Thus, an exclusive member for mounting the brake caliper19of the disk brake18thereon can be omitted. Further, since the wheel speed sensor32is attached to the mounting boss17, and since the mounting boss17is formed integrally with and continuously from the axle supporting portion6aof the right side, an exclusive member for attaching the wheel speed sensor thereto can be omitted. Thus, the number of members can be reduced.

In addition, the wheel speed sensor32is attached to the under surface of the lower one17of the mounting bosses16,17. The mounting bosses16,17are formed to be separated in a vertical direction on the right leg6of the legs6,7of the front fork5. Thus, the space below the mounting boss17is efficiently utilized.

Although the present embodiment of the invention has been described above for purposes of understanding, the invention is not limited thereto, but may be embodied with various modifications and variations, without departing from the spirit and scope of the invention as defined in the claims.