Disk brake

A front disk brake includes a brake caliper having a pair of caliper side mount portions, and a caliper bracket having a pair of bracket side mount portions. The brake caliper includes an oblong-shared lower-side counterbore and a circular-shaped upper-side counterbore, the lower-side counterbore being oblong sectional shaped in the arrangement direction of the lower-side counterbore and the upper-side counterbore paired therewith. The caliper bracket includes lower-side and upper side circular-shaped counterbores which are opposed, respectively, to the counterbores of the brake caliper. The brake caliper is fixed to the caliper bracket by mounting fastening bolts in bolt passing holes and screw holes formed respectively in the mount portions. The bolt passing holes and the screw holes are provided at their portions on the sides of opposed surfaces with counterbores in which collar members are to be fitted.

CROSS-REFERENCE TO RELATED APPLICATIONS

This nonprovisional application is related to Patent Application No. 2003-317549, filed in Japan on Sep. 9, 2003, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk brake for use in a vehicle such as a motorcycle.

2. Description of Background Art

Conventionally, disk brakes used in vehicles generally have a structure in which a brake caliper is provided with a pair of caliper side mount portions, while a vehicle body side support portion is provided with a pair of support portion side mount portions. Opposed surfaces of the mount portions are set in abutting relationship. Fastening bolts are mounted in bolt mount holes formed respectively in the mount portions. Accordingly, the brake caliper is fixed to the vehicle body side support portion. Among the disk brakes of this type, there is a disk brake in which a collar member is disposed in portions, on the opposed surface sides, of bolt mount holes in each abutting set of the caliper side mount portion and the support portion side mount portion, in such a manner that the collar member extends from one to the other of the portions. Therefore, the collar members achieve positioning of the brake caliper in the direction along the opposed surfaces, and positioning of the brake caliper in the direction orthogonal to the opposed surfaces is achieved by the mutual abutting of the opposed surfaces (see, for example, Japanese Patent Laid-open No. 2003-65369).

In order to fix the brake caliper accurately relative to the vehicle body side support portion, the tolerance of the inter-axial distance of each pair of bolt mount holes is in some cases set to be smaller than the general tolerance, since it is desirable to minimize chattering of the collar members. This is important for preventing the brake caliper from deviating in the direction orthogonal to the plane of the brake disk, in the radial mount type disk brake in which each of the bolt mount holes is provided in parallel to the radial direction of the brake disk. Thus, for efficiently manufacturing the brake caliper and the vehicle body side support portion, there is a demand for a disk brake so configured that the tolerance of the inter-axial distance of the bolt mount holes can be the general tolerance.

SUMMARY OF THE INVENTION

Accordingly, the present invention aims at providing a disk brake, which makes it possible to efficiently manufacture a brake caliper and a vehicle body side support portion while maintaining positioning accuracy of the brake caliper.

As a means for solving the above-mentioned problems, an embodiment of the present invention provides a disk brake (e.g., a front disk brake26in the embodiment) including a brake caliper (e.g., a brake caliper24in the embodiment) having pistons (e.g., pistons PI in the embodiment) and brake pads (e.g., brake pads PA in the embodiment) for pressing a brake disk (e.g., a brake disk25in the embodiment). In addition, a vehicle body side support portion (e.g., a caliper bracket42in the embodiment) is provided on the vehicle body side for supporting the brake caliper. The brake caliper is provided with a pair of caliper side mount portions (e.g., caliper side mount portions48,49in the embodiment). The vehicle body side support portion is provided with a pair of support portion side mount portions (e.g., bracket side mount portions52,53in the embodiment) corresponding to the caliper side mount portions. Opposed surfaces of the mount portions (e.g., a caliper side opposed surface54and a bracket side opposed surface55in the embodiment) abut each other. Furthermore, fastening bolts (e.g., fastening bolts40,41in the embodiment) are mounted in mount holes (e.g., bolt passing holes46,47, and screw holes50,51in the embodiment) formed in the mount portions. Accordingly, the brake caliper is fixed to the vehicle body side support portion. Furthermore, each of the mount holes is provided with a counterbore (e.g., each of upper-side and lower-side counterbores56,57,58,59in the embodiment) at its portion on the opposed surface side. A collar member (e.g., each of collar members60,61in the embodiment) extending from one to the other of each opposed set of the counterbores is fitted in the opposed set of the counterbores. In addition, at least one of the counterbores is formed in an oblong sectional shape elongate along the arrangement direction of itself and the counterbore paired therewith.

With this configuration, at the time of mounting the brake caliper to the vehicle body side support portion, the brake caliper is positioned in the direction orthogonal to the plane of the brake disk by only fitting the collar members in the upper-side and lower-side counterbores. Furthermore, the disk caliper is positioned in the radial direction of the brake disk by mutual abutting of the bracket side opposed surfaces and the caliper side opposed surfaces.

In addition, even when an error is generated in the inter-axial distance (the distance along the arrangement direction) of the two mount holes, the error can be absorbed by the counterbore formed in an oblong sectional shape. Therefore, the mounting of the brake caliper is not hampered and the positioning accuracy of the brake caliper can be maintained.

According to another embodiment of the present invention, the positioning of the brake caliper in the direction orthogonal to the plane of the brake disk is particularly important in the case of the so-called radial mount type disk brake in which each of the fastening bolts is disposed in parallel to the radial direction of the brake disk.

According to a further embodiment of the present invention, the counterbores provided in the pair of the caliper side mount portions and the counterbores provided in the pair of bracket side mount portions are respectively arranged in the rotating direction of the brake disk. At least one counterbore in the pair of the counterbores, located on the upstream side with respect to the rotating direction of the brake disk, is formed in an oblong shape in section.

With this configuration, at the time of mounting the brake caliper to the vehicle body side support portion, the brake caliper is positioned in the arrangement direction of the mount holes (the arrangement direction of the counterbores) by the counterbores on the downstream side with respect to the rotating direction of the brake disk. An error in the inter-axial distance of the mount holes (the inter-axial distance of the counterbores) is absorbed by the counterbores on the upstream side with respect to the rotating direction of the brake disk.

According to an embodiment of the present invention, the brake caliper can be fixed accurately relative to the caliper bracket, without requiring fine adjustment. In addition, since the counterbore formed in the oblong sectional shape absorbs an error in the inter-axial distance of the counterbores, the tolerance of the inter-axial distance of the counterbores can be a general tolerance. Therefore, the brake caliper and the vehicle body side support portion can be manufactured efficiently.

According to an embodiment of the present invention, the positioning of the brake caliper in the direction orthogonal to the plane of the brake disk is particularly important in the case of the so-called radial mount type disk brake. Therefore, the effect of maintaining the positioning accuracy of the brake caliper is augmented.

In addition, while the overall length of the mount holes for the fastening bolt is enlarged in the case of the radial mount type disk brake, the embodiment of the present invention makes it sufficient to form only the counterbore in an oblong sectional shape. Therefore, the machining of the brake caliper and the vehicle body side support portion is facilitated, as compared with the case where the mount holes are formed in an oblong sectional shape over the entire length thereof.

According to an embodiment of the present invention, it is possible to eliminate the chattering of the brake caliper located on the downstream side with respect to the rotating direction of the brake disk, in the rotating direction of the brake disk. Therefore, a feeling of rigidity at the time of braking can be secured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with reference to the accompanying drawings, wherein the same or similar elements have been identified by the same reference numeral throughout the several views. It should be noted that the sides or directions such as the front (forward), rear (rearward), left and right sides (directions) in the following description are the same as the sides or directions with respect to the vehicle.

As shown inFIG. 1, a front fork3shaft-supporting a front wheel2of a motorcycle1is steerably supported on a head pipe6provided at a front end portion of a vehicle body frame5through a steering stem4. A main frame7of the vehicle body frame5extends downwardly rearwards from the head pipe6. Rear end portions of the main frame7are bent downwards, to be in continuity with pivot plates8. In addition, a front end portion of a seat frame9extending upwardly rearwards is connected to a rear portion of the main frame7.

A base end portion of a swing arm13is swingably mounted to the pivot plates8through a pivot shaft11. A rear wheel12is shaft-supported on a tip end portion of the swing arm13. An upper end portion of a cushion unit14is mounted to an upper portion on the base end side of the swing arm13. Furthermore, a lower end portion of the cushion unit14is joined to the pivot plates8at a position lower than the pivot shaft11through a link mechanism15.

A fuel tank17is mounted on the upper side of the main frame7. A water cooled type four-cylinder engine18is mounted on the lower side of the main frame7. In addition, a driver's seat19and a pillion seat20for a passenger are provided on the rear side of the fuel tank17. Steps21for the driver are attached to rear portions of the pivot plates8, while steps22for the passenger are attached to lower portions of the seat frame9.

A steering handle23is mounted to an upper end portion of the front fork3. In addition, brake calipers24are mounted to lower end portions of the front fork3through caliper brackets (vehicle body side support portions)42. Brake disks25corresponding to the brake calipers24are mounted to hub portions of the front wheel2, thereby constituting front disk brakes (disk brakes)26according to the present invention. In addition, a rear disk brake having the same configuration as that of the front disk brakes26is provided on the right side of the rear wheel12.

A vehicle body front portion of the motorcycle1is covered with a front cowl27, and the surroundings of the seat frame9are covered with a rear cowl28. A rear sprocket29is mounted to the left side of the rear wheel12. A drive chain31is wrapped around the rear sprocket29and a drive sprocket30disposed on the left side of a rear portion of the engine18. Accordingly, the drive force of the engine18is transmitted to the rear wheel12.

Throttle bodies33corresponding respectively to the cylinders are connected to rear portions of the cylinders32of the engine18. Each of the throttle bodies33is connected to an air cleaner case34disposed between the main frame7and the fuel tank17. Exhaust pipes35corresponding respectively to the cylinders are connected to front portions of the cylinders32. The exhaust pipes35are bent downwards from front wall portions of the cylinders32, pass under a crankcase36, are then bent upwards on the rear side of the pivot plates8, and are connected to a silencer37supported on the seat frame9. A radiator38for cooling the engine18is disposed on the front side of the exhaust pipes35.

As shown inFIG. 2, the front disk brake26is of the so-called radial mount type in which the brake caliper24is fixed to the caliper bracket42by use of two fastening bolts40,41disposed in parallel to the radial directions of the brake disk25. The brake disk25is provided to be rotatable as one body with the front wheel2about a front axle43. In addition, the caliper bracket42is disposed on the outer side in the width direction of the brake disk25(on the left side of the brake disk25in the case of the brake disk25provided on the left side of the front wheel2), and is provided as one body with the lower end portion of the front fork3. Hydraulic pressure generated in a master cylinder (omitted in the figure) is transmitted through brake hoses44to the brake calipers24, whereby the rotation of the brake disks25and the front wheel2is braked.

Referring toFIGS. 3 and 4, the brake caliper24is of the so-called opposed piston type, including a caliper main body45provided astride the brake disk25on the outer side in the radial direction of the brake disk25. A pair of brake pads PA (indicated by broken lines inFIG. 3only) are disposed on both sides of the brake disk25and are supported on the caliper main body45so as to be movable in the direction orthogonal to the plane of the brake disk25(hereinafter referred to as the plane orthogonal direction). Pistons PI (indicated by broken lines inFIG. 3only) are disposed respectively at positions on the opposite side of the brake disk of the brake pads and are fitted in cylinders formed in the caliper main body45.

The brake caliper24is provided at its upper portion and lower portion with a pair of caliper side mount portions48,49having bolt passing holes (mount holes)46,47parallel to each other. On the other hand, the caliper bracket42is provided at its upper portion and lower portion with a pair of bracket side mount portions (support portion side mount portions)52,53having screw holes (mount holes)50,51provided with screw threads in the inner circumferences thereof (seeFIG. 2). The caliper side mount portions48,49and the bolt passing holes46,47are arranged (arrayed) along the rotating direction of the brake disk25. Similarly, the bracket side mount portions52,53and the screw holes50,51are arranged (arrayed) along the rotating direction of the brake disk25.

The fastening bolts40,41are passed through the bolt passing holes46,47from the side of the brake caliper24and are fastened into the screw holes50,51, whereby the brake caliper24is fixed to the caliper bracket42. The bolt passing holes46,47and the screw holes50,51are so disposed that they are at equal pitches from the center position (indicated by dot-dash line A in the figures) of the brake caliper24in the circumferential direction of the brake disk25. Incidentally, the center position is located on a diameter of the brake disk25in side view of the vehicle body. In addition, the bolt passing holes46,47and the screw holes50,51are provided on the outer side in the vehicle width direction (the side pointed by arrow LH inFIG. 4) of the brake disk25correspondingly to the caliper bracket42.

As shown inFIG. 2, at the time of fixing the brake caliper24to the caliper bracket42, each of the upper and lower sets of the caliper side mount portions48,49and the bracket side mount portions52,53abut each other on a plane orthogonal to the axes B, C of the bolt passing holes46,47and the screw holes50,51, whereby the brake caliper24is positioned in the radial direction of the brake disk25. The abutting surfaces of the brake caliper24are referred to as caliper side opposed surfaces (opposed surfaces)54, and the abutting surfaces of the caliper bracket42are referred to as bracket side opposed surfaces (opposed surfaces)55. In addition, the distance between the axes B, C of the bolt passing holes46,47and the screw holes50,51(the inter-axial distance of the bolt passing holes46,47and the screw holes50,51) is denoted by D.

The brake caliper24is mounted to the caliper bracket42from the upper rear side. The opposed surfaces54,55are so inclined that they are located on the front side as one goes upwards. The axes B, C of the bolt passing holes46,47and the screw holes50,51are so inclined that they are located on the upper side as one goes rearwards. The caliper side mount portion49and the bracket side mount portion53on the lower side are located on the rear side relative to those on the upper side.

The upper and lower bolt passing holes46,47are provided at their portions on the side of the caliper side opposed surfaces54with an upper-side counterbore (counterbore)56and a lower-side counterbore (counterbore)57, respectively, which are formed by displacing the caliper side opposed surfaces54in the surroundings of the openings thereof in the direction away from the bracket side opposed surfaces55(seeFIGS. 3 and 5). In addition, the upper and lower screw holes50,51are provided at their portions on the side of the bracket side opposed surfaces55with an upper-side counterbore (counterbore)58and a lower-side counterbore (counterbore)59, respectively, which are formed by displacing the bracket side opposed surfaces55in the surroundings of the openings thereof in the direction away from the caliper side opposed surfaces54.

The upper-side counterbore56and the lower-side counterbore57are arranged along the rotating direction of the brake disk25. Similarly, the upper-side counterbore58and the lower-side counterbore59are arranged along the rotating direction of the brake disk25.

A collar member60is fitted in the upper-side counterbores56,58so as to extend from one to the other of the counterbores56,58, and the upper-side fastening bolt40penetrates through the inside of the collar member60. Similarly, a collar member61is fitted in the lower-side counterbores57,59so as to extend from one to the other of the counterbores57,59, and the lower-side fastening bolt41penetrates through the inside of the collar member61.

The upper-side counterbores56,58and the lower-side counterbores57,59are formed simultaneously with the machining of the corresponding bolt passing holes46,47or screw holes50,51by use of, for example, a step drill or the like. Therefore, the tolerance of the inter-axial distance D of the bolt passing holes46,47in the upper and lower caliper side mount portions48,49and the tolerance of the inter-axial distance of the upper-side and lower-side counterbores56,57corresponding to the bolt passing holes46,47are roughly equal to each other. Similarly, the tolerance of the inter-axial distance D of the screw holes50,51in the upper and lower bracket side mount portions52,53and the tolerance of the inter-axial distance of the upper-side and lower-side counterbores58,59corresponding to the screw holes50,51are roughly equal to each other.

The upper-side counterbores56,58located on the downstream side with respect to the rotating direction of the brake disk25are formed in a true circular sectional shape having the axis B in common with the upper-side bolt passing hole46and screw hole50, and the inner circumferential surfaces thereof match the outer circumferential surface of the collar member60. On the other hand, as for the lower-side counterbores57,59located on the upstream side with respect to the rotating direction of the brake disk25, the lower-side counterbore59formed in the bracket side mount portion53is formed in a true circular sectional shape having the axis C in common with the bolt passing hole47and the screw hole51, whereas the lower-side counterbore57formed in the caliper side mount portion49is formed in an oblong sectional shape which has its center on the axis C of the bolt passing hole47(and the screw hole51) and which is elongate along the arrangement direction (the pitch direction) of both the bolt passing holes46,47(seeFIG. 5).

As shown inFIG. 6, the inner circumferential surface of the lower-side counterbore59in the bracket side mount portion53match the outer circumferential surface of the collar member61. The width in the transverse direction of the inner circumferential surface of the lower-side counterbore57in the caliper side mount portion49is roughly equal to the outside diameter of the collar member61. However, the width in the longitudinal direction is equal to a value obtained by adding, to the outside diameter of the collar member61, error portions E, E determined by taking into account the general tolerance of the inter-axial distance D of both the bolt passing holes46,47(namely, the general tolerance of the inter-axial distance of the upper-side and lower-side counterbores56,57) and the general tolerance of the inter-axial distance D of both the screw holes50,51(namely, the general tolerance of the inter-axial distance of the upper-side and lower-side counterbores58,59) (seeFIG. 5). Incidentally, the inner circumferential surfaces on both end sides in the longitudinal direction of the lower-side counterbore57are halves of a hollow cylindrical surface, which match the outer circumferential surface of the collar member61.

In the condition where the collar members60,61are fitted respectively in the upper-side counterbores56,58and in the lower-side counterbores57,59and the brake caliper24is mounted to the caliper bracket42, the lower-side collar member61is located at the center in the longitudinal direction of the lower-side counterbore57in the caliper side mount portion49.

According to the above-described embodiment, as shown inFIG. 2, the front disk brake26includes the brake caliper24having the pistons PI and the brake pads PA for pressing the brake disk25. The caliper bracket42is provided on the vehicle body side for supporting the brake caliper24. The brake caliper24is provided with the pair of caliper side mount portions48,49. The caliper bracket42is provided with the pair of bracket side mount portions52,53corresponding to the caliper side mount portions48,49. The caliper side opposed surfaces54of the caliper side mount portions48,49and the bracket side opposed surfaces55of the bracket side mount portions52,53are made to abut each other. The fastening bolts40,41are mounted in the bolt passing holes46,47and the screw holes50,51formed in the mount portions48,49,52,53. Accordingly, the brake caliper24is fixed to the caliper bracket42.

The bolt passing holes46,47in the caliper side mount portions48,49are provided respectively with the upper-side and lower-side counterbores56,57at their portions on the side of the caliper side opposed surfaces54. The screw holes50,51in the bracket side counterbores52,53are provided respectively with the upper-side and lower-side counterbores58,59at their portions on the side of the bracket side opposed surfaces55. The collar member60is fitted in the opposed set of the upper-side counterbores56,58so as to extend from one to the other of the upper-side counterbores56,58. The collar member61is fitted in the opposed set of the lower-side counterbores57,59so as to extend from one to the other of the lower-side counterbores57,59.

At the time of mounting the brake caliper24to the caliper bracket42, the brake caliper24is positioned relative to the caliper bracket42in the direction orthogonal to the plane of the brake disk25by only fitting the collar members60,61respectively in the sets of the upper-side and lower-side counterbores56,57,58,59. In addition, the brake caliper24is necessarily positioned relative to the caliper bracket42in the radial direction of the brake disk25by the mutual abutting of the caliper side opposed surfaces54and the bracket side opposed surfaces55. This ensures that the brake caliper24is fixed to the caliper bracket42accurately, without requiring fine adjustment.

The lower-side counterbore57formed in the caliper side mount portion49is formed in an oblong sectional shape, which is elongate along the arrangement direction of the lower-side counterbore57and the upper-side counterbore56paired therewith. Specifically, the width in the transverse direction of the inner circumferential surface of the lower-side counterbore57is roughly equal to the outside diameter of the collar member61. However, the width in the longitudinal direction is equal to a value determined by adding, to the outside diameter of the collar member61, the error portions determined by taking into account the general tolerances of the inter-axial directions of both the bolt passing holes46,47and both the screw holes50,51.

Thus, at least one counterbore (the lower-side counterbore57in the caliper side mount portion49) is formed in an oblong sectional shape elongate in the arrangement direction of itself and the counterbore (the upper-side counterbore56in the caliper side mount portion48) paired therewith. This ensures that even when errors are generated respectively in the inter-axial distance of the upper-side and lower-side counterbores56,57in the caliper side mount portions48,49and in the inter-axial distance of the upper-side and lower-side counterbores58,59in the bracket side mount portions52,53, the errors can be absorbed by the counterbore formed in an oblong sectional shape. Therefore, the mounting of the brake caliper24is not hampered, and the positioning accuracy can be maintained.

Therefore, the tolerances of the inter-axial distances of the paired upper-side counterbores56,58and the lower-side counterbores57,59can be general tolerances, so that the brake caliper24and the vehicle body side support portion can be manufactured efficiently.

In addition, at the time of mounting the brake caliper24to the caliper bracket42, positioning of the brake caliper24in the arrangement direction of the upper-side counterbores56,58and the lower-side counterbores57,59is achieved by the upper-side counterbores56,58located on the downstream side with respect to the rotating direction of the brake disk25. Errors in the inter-axial distances of the upper-side counterbores56,58and the lower-side counterbores57,59are absorbed by the lower-side counterbores57,59located on the upstream side with respect to the rotating direction of the brake disk25. Therefore, it is possible to eliminate chattering of the brake caliper24in the rotating direction of the brake disk25due to the setting of the counterbore formed in the oblong sectional shape, to restrain the mounting rigidity of the brake caliper24from being lowered, and to secure a feeling of rigidity at the time of braking.

The configuration in which the portion(s) to be formed in an oblong sectional shape is only the lower-side counterbore57makes it possible to enhance the manufacturability of the brake caliper24, as compared with the case where the bolt passing hole47is formed in an oblong sectional shape over the entire length thereof in the radial mount type front disk brake26in which the entire length of the bolt passing hole47is large. In addition, in the radial mount type front disk brake26, the positioning of the brake caliper24in the direction orthogonal to the plane of the brake disk25is important and, therefore, the effect of the maintaining the positioning accuracy of the brake caliper24is great.

Incidentally, the present invention is not limited to the above-described embodiment. For example, there may be adopted a configuration in which the brake caliper24is provided with the screw holes50,51, while the caliper bracket42is provided with the bolt passing holes46,47, and the fastening bolts40,41are mounted in position from the side of the caliper bracket42. In addition, a disk brake with a configuration in which the brake caliper is mounted to the vehicle body side support portion by fastening bolts disposed in parallel to the plane orthogonal direction of the brake disk25may be adopted, instead of the radial mount type disk brake.

Furthermore, the disk brake may be a floating (pin slide) type disk brake, instead of the opposed piston type disk brake. Specifically, the disk brake may be a disk brake in which a brake caliper including a caliper main body having a piston and a brake pad for pressing one side surface of a brake disk, and a reaction portion having a brake pad for pressing the other side surface of the brake disk, is fixed to a caliper bracket though a caliper support by fastening bolts penetrating through the brake caliper itself. In this case, the caliper support interposed between the brake caliper and the caliper bracket belongs to the brake caliper side.

The same functions or effects as those of the above-described embodiment can be obtained in the case where the brake caliper is provided with at least two mount holes for passing the fastening bolts therethrough. One of the mount holes is formed in a true circular sectional shape, and at least one of the other mount hole(s) is formed in an oblong sectional shape elongate in the arrangement direction of this mount hole and the mount hole formed in the true circular sectional shape. In addition, in this form of disk brake, it is possible to adopt the so-called radial mount type in which each of the fastening bolts is disposed in parallel to the radial direction of the brake disk.