Disk brake for vehicle

1. Field of the Invention

The present invention relates to a disk brake for a vehicle used in a motor vehicle or a motor bicycle, and more particularly to a structure of a pad retainer that supports lug pieces of a back plate of a friction pad by pad guide grooves of caliper support arms.

2. Description of the Related Art

In a disk brake in which lug pieces respectively protruding at both side parts of a back plate of a friction pad are supported by pad guide grooves formed and opposed to each other in a pair of caliper support arms so as to move the friction pad in the axial direction of a disk, a pad retailer formed with a metal thin plate is ordinarily interposed between the pad guide grooves and the lug pieces. In such a pad retainer, a pad retainer is known that includes resilient parts abutting on the lug pieces to urge the lug pieces toward sides opposite to a disk rotor and urge the lug pieces toward outer side surfaces of the pad guide grooves in the radial direction of the disk, so that the pull-back and the backlash of the friction pad are suppressed by them (for instance, see Japanese Patent No. 3934063).

Further, as an attaching structure of a pad retainer to caliper support arms, an attaching structure is known that pad retainer attaching parts are provided in outer sides of pad guide grooves in the radial direction of a disk, end parts of outer side pieces of the pad retainer in the radial direction of the disk arranged in the outer side surfaces of the pad guide grooves in the radial direction of the disk are bent along end surfaces of the pad retainer attaching parts and extended to the outer side surfaces of the pad retainer attaching parts in the radial direction of the disk to form attaching pieces and the pad retainer attaching parts are sandwiched between the attaching pieces and the outer side pieces in the radial direction of the disk to attach the pad retainer to the caliper support arms (for instance, see JP-A-2000-161401).

In the structures disclosed in Japanese Patent No. 3934063 or the JP-A-2000-161401, the sliding resistance of the lug pieces of the friction pad can be reduced or the backlash can be suppressed by the pad retainer. In a vibration arising during an ordinary driving of a vehicle, the lug pieces of the friction pad can be held at prescribed positions in a stable way by an urging force of resilient parts of the pad retainer. However, when the vibration larger than an ordinary vibration is applied to a vehicle body, for instance, when the vehicle gets over a stepped part during the driving, occasionally, the friction pad temporarily moves inside in the radial direction of the disk against the urging force of the pad retainer, then, is urged outside in the radial direction of the disk by the urging force of the pad retainer and the surfaces of the lug pieces collide with the outer side surfaces of the pad guide grooves in the radial direction of the disk through the pad retainer to generate cronk noise (collision noise).

It is an object of the present invention to provide a disk brake for a vehicle that can suppress the backlash of a friction pad by a pad retainer and can prevent the generation of cronk noise.

According an aspect of the invention, there is provided a disk brake for a vehicle including: a caliper bracket fixed to a vehicle body; a pair of caliper support arms provided in the caliper bracket that extend and stride over an outer edge of a disk rotor in the axial direction of a disk; U shaped pad guide grooves that are provided in the caliper support arms in opposed forms and have outer side surfaces in the radial direction of the disk, inner side surfaces in the radial direction of the disk and opposed surfaces which connect together both the side surfaces; and lug pieces that respectively protrude on both side parts of back plates of friction pads arranged with the disk rotor sandwiched between them and are respectively supported by the pad guide grooves through a pad retainer, the pad retainer including a pair of retainer parts attached to the pad guide grooves at both the sides of the disk rotor, a connecting piece that strides over the outer edge of the disk rotor to connect the pair of retainer parts and pad resilient parts that urge the friction pads outward in the radial direction of the disk, wherein: the retainer parts include inner side pieces arranged along the inner side surfaces of the pad guide grooves in the radial direction of the disk, outer side pieces arranged along the outer side surfaces of the pad guide grooves in the radial direction of the disk and interior pieces that connect the outer side pieces to the inner side pieces in interior parts of the pad guide grooves and are arranged along the opposed surfaces; and the outer side pieces include impact suppressing parts that restrain the lug pieces from colliding with the outer side surfaces in the radial direction of the disk through the outer side pieces.

The impact suppressing parts may be stepped parts formed by bending the outer side pieces. The caliper support arms may include pad retainer attaching parts having attaching surfaces parallel to the outer side surfaces in the radial direction of the disk in outer sides of the pad guide grooves in the radial direction of the disk, end parts of groove opening side parts of the outer side pieces may be bent back along the attaching surfaces of the pad retainer attaching parts to form attaching pieces, and the pad retainer attaching parts may be sandwiched between the attaching pieces and the outer side pieces to attach the pad retainer to the caliper support arms.

In the impact suppressing parts, the outer side pieces may be bent in stepped forms so that groove interior parts of the outer side pieces are arranged more outside in the radial direction of the disk than groove opening side parts to form stepped parts, and the pad retainer may be attached to the caliper support arms in such a way that the pad retainer attaching parts are held at three positions including groove interior side abutting parts and groove opening side abutting parts of the outer side pieces abutting on the outer side surfaces in the radial direction of the disk and attaching piece side abutting parts of the attaching pieces abutting on the attaching surfaces between the groove interior side abutting parts and the groove opening side abutting parts in the circumferential direction of the disk.

The interior pieces may be connected to the outer side pieces at acute angles α thereto. The pad resilient parts may be formed by gradually inclining the end parts of elongated pieces extended to the disk rotor through elastic loop parts that are extended from the sides of the inner side pieces opposite to the disk rotor and bent outward in circular arc forms in the radial direction of the disk, outward in the radial direction of the disk, and the lug pieces may be urged outward in the radial direction of the disk and urged toward the direction opposite to the disk rotor by the elongated pieces.

According to the disk brake for a vehicle of the present invention, since the lug pieces of the friction pad are urged outside in the radial direction of the disk by the pad resilient parts of the pad retainer, even when the vibration occurs during an ordinary driving, the friction pad is held at a prescribed position in a stable condition. Further, even when the vibration larger than an ordinary vibration is applied to a vehicle body, for instance, when the vehicle gets over a stepped part during the driving, the friction pad temporarily moves inside in the radial direction of the disk against the urging force of the pad resilient parts, then, is urged outside in the radial direction of the disk by the urging force of the pad resilient parts and the lug pieces are apt to collide with the outer side surfaces of the pad guide grooves in the radial direction of the disk through the outer side pieces of the pad retainer, since the outer side pieces are provided with the impact suppressing parts for suppressing the collision of the lug pieces with the outer side surfaces in the radial direction of the disk through the outer side pieces, the force of the lug pieces in the direction of collision is absorbed by the impact suppressing parts and the generation of cronk noise can be prevented.

Further, when the impact suppressing parts are formed by stepped parts which are formed by bending the outer side pieces, the impact suppressing parts can be formed by a simple method that the outer side pieces are merely bent, and the force of the lug pieces in the direction of collision can be effectively absorbed by spaces formed between the outer side pieces and the outer side surfaces of the pad guide grooves in the radial direction of the disk.

Further, in the outer sides of the pad guide grooves of the caliper support arms in the radial direction of the disk, the pad retainer attaching parts are provided that have the attaching surfaces parallel to the outer side surfaces in the radial direction of the disk. The pad retainer is attached to the caliper support arms in such a way that the end parts of the groove opening side parts of the outer side pieces are bent back along the attaching surfaces of the pad retainer attaching parts to form the attaching pieces and the pad retainer attaching parts are sandwiched between the attaching pieces and the outer side pieces to attach the pad retainer to the caliper support arms. Thus, the pad retainer can be simply and assuredly attached to a prescribed position.

Further, in the impact suppressing parts, the outer side pieces are bent in stepped forms so that the groove interior parts of the outer side pieces are arranged more outside in the radial direction of the disk than the groove opening side parts to form the stepped parts. The pad retainer is attached to the caliper support arms in such a way that the pad retainer attaching parts are held at three positions including the groove interior side abutting parts and the groove opening side abutting parts of the outer side pieces abutting on the outer side surfaces in the radial direction of the disk and the attaching piece side abutting parts of the attaching pieces abutting on the attaching surfaces between the groove interior side abutting parts and the groove opening side abutting parts in the circumferential direction of the disk. Thus, the inner sides of the interior pieces in the radial direction of the disk are attached to be inclined toward the central parts of the friction pads. Accordingly, the lug pieces can be urged toward the opposed pad guide grooves by the interior pieces. Even when the force moving in the circumferential direction of the disk is applied to the friction pads, for instance, when the forward movement of the vehicle is changed to the backward movement, the lug pieces can be restrained from colliding with the opposed surfaces of the pad guide grooves through the interior pieces and the generation of the cronk noise can be prevented. Further, since the interior pieces are connected to the outer side pieces at acute angles, an urging force that urges the lug pieces toward the pad guide grooves can be increased.

Further, since the pad resilient parts are formed by gradually inclining the end parts of the elongated pieces extended to the disk rotor through the elastic loop parts from the sides of the inner side pieces opposite to the disk rotor outward in the radial direction of the disk, the lug pieces can be urged outward in the radial direction of the disk, and the lug pieces can be urged toward the direction opposite to the disk rotor. The friction pads can be held at prescribed positions in a stable way by a simple structure and the friction pads after the braking operation can be assuredly pulled back.

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawing which is given by way of illustration only, and thus is not limitative of the present invention and wherein:

FIG. 1 is an enlarged sectional view of main parts of a disk brake according to a first exemplary embodiment of the present invention;

FIG. 2 is a front view of the disk brake in the first exemplary embodiment;

FIG. 3 is a sectional view taken along a line II-II in FIG. 2 ;

FIG. 4 is a perspective view of a pad retainer in the first exemplary embodiment;

FIG. 5 is a partly sectional rear view of the disk brake in the first exemplary embodiment;

FIG. 6 is a sectional view taken along a line V-V in FIG. 2 ;

FIG. 7 is an explanatory view showing a state that the pad retainer is attached to a pad guide groove in the first exemplary embodiment;

FIG. 8 is an explanatory view showing a state that a pad retainer is attached to a pad guide groove in a second exemplary embodiment of the present invention;

FIG. 9 is an enlarged sectional view of main parts of a disk brake according to a third exemplary embodiment of the present invention; and

FIG. 10 is a perspective view of a pad retainer in the third exemplary embodiment.

FIGS. 1 to 7 are diagrams showing a first exemplary embodiment of a disk brake for a vehicle of the present invention. An arrow mark A designates a rotating direction of a disk rotor that rotates integrally with a front wheel when a vehicle moves forward. A disk come-out side and a disk come-in side which are described below indicate sides when the vehicle moves forward.

The disk brake 1 for the vehicle includes a disk rotor 2 rotating integrally with a wheel, a caliper bracket 3 fixed to a vehicle body at one side part of the disk rotor 2 , a calipers body 5 supported on caliper support arms 3 a and 3 a so as to be movable in the axial direction of a disk through a pair of slide pins 4 and 4 and a pair of friction pads 6 and 6 opposed to each other with the disk rotor 2 sandwiched between them inside an action part 5 a and a reaction part 5 b of the caliper body 5 .

The caliper body 5 includes the above-described action part 5 a and the reaction part 5 b arranged at both the sides of the disk rotor 2 and a bridge part 5 c that strides over an outer edge of the disk rotor 2 to connect the action part 5 a to the reaction part 5 b . In the action part 5 a , a cylinder hole 7 opened to the disk rotor 2 side is provided. In the cylinder hole 7 , a cylindrical piston 8 with a bottom is accommodated. The piston 8 moves toward the disk rotor in the cylinder hole 7 by pressure liquid supplied to a hydraulic chamber 9 in a bottom part of the cylinder hole 7 . Further, in the side parts of the action part 5 a , vehicle body attaching arms 5 d and 5 d protrude. At the ends of the vehicle body attaching arms 5 d respectively, the above-described slide pins 4 respectively protrude through attaching bolts.

The caliper support arms 3 a and 3 a sandwich both the sides of the bridge part 5 c from both the side parts of the caliper bracket 3 and stride over the outer edge of the disk rotor 2 in the axial direction of the disk and further extend toward a central part of the disk along the side wall of the reaction part 5 b in the other end part of the disk rotor 2 . End parts of the caliper support arms 3 a and 3 a are connected together by a tie rod 3 b to improve the rigidity of both the support arms 3 a and 3 a to which a braking torque is applied.

In the caliper support arms 3 a and 3 a respectively, guide holes 3 c are formed for accommodating the slide pins 4 . Further, in both the caliper support arms 3 a and 3 a , four pad guide grooves 3 d are provided that face each other respectively in the side parts of the disk rotor 2 . The pad guide grooves 3 d are respectively formed in U shapes having outer side surfaces 3 e in the radial direction of the disk, inner side surfaces 3 f in the radial direction of the disk and opposed surfaces 3 g that connect both the side surfaces 3 e and 3 f . Each of the friction pad 6 has lug pieces 6 b and 6 b respectively protruding at both side parts of a back plate 6 a which are respectively supported by the pad guide grooves 3 d and 3 d in the disk come-in side and the disk come-out side through a pad retainer 10 . In outer sides of the pad guide grooves 3 d and 3 d in the radial direction of the disk, pad retainer attaching parts 3 i and 3 i are respectively provided which have attaching surfaces 3 h parallel to the outer side surfaces 3 e in the radial direction of the disk.

The above-described pad retainer 10 includes a pair of retainer parts 10 a and 10 a attached to the pad guide grooves 3 d and 3 d in both the sides of the disk rotor in the disk come-in side or the disk come-out side, pad resilient parts 10 c and 10 c extending to the disk rotor side through elastic loop parts 10 b and 10 b provided in the disk rotor side opposite to that of the retainer parts 10 a and 10 , attaching pieces 10 d and 10 d abutting on the attaching surfaces 3 h of the pad retainer attaching parts 3 i and 3 i of the caliper support arms 3 a and a connecting piece 10 e striding over the outer edge of the disk rotor 2 to connect the upper parts of the attaching pieces 10 d and 10 d . The retainer parts 10 a respectively include inner side pieces 10 f and outer side pieces 10 g that face inside and outside in the radial direction of the disk with the lug pieces 6 b of the friction pad 6 sandwiched between them and interior pieces 10 h that connect both the pieces 10 f and 10 g in interior parts of the pad guide grooves 3 d and 3 d . The outer side pieces 10 g are connected to the interior pieces 10 h at right angles thereto.

The outer side pieces 10 g are respectively bent in stepped forms so that groove interior parts 10 i of the outer side pieces 10 g are arranged more outside in the radial direction of the disk than groove opening side parts 10 k to form stepped parts 10 m (impact suppressing parts of the present invention). Further, end parts of the groove opening side parts 10 k of the outer side pieces 10 g are bent back along the end surfaces of the pad retainer attaching parts 3 i to be extended toward outer side surfaces of the pad retainer attaching parts 3 i in the radial direction of the disk so that the attaching pieces 10 d may be elastically deformed. Thus, the pad retainer attaching parts 3 i are sandwiched between the attaching pieces 10 d that are elastically deformed outward and the outer side pieces 10 g.

The elastic loop parts 10 b are formed by bending back elongated pieces extended from the inner side pieces 10 f toward an opposite direction to the disk rotor in circular arc forms toward the disk rotor from outer sides in the radial direction of the disk. The pad resilient parts 10 c are located in the end sides of the elongated pieces extended toward the disk rotor from the bent back ends of the elastic loop parts 10 b . The pad resilient parts 10 c have a length sufficiently corresponding to a distance that the lug pieces 6 b of the friction pad 6 move until a lining is completely worn from the first time when the lining is new. The pad resilient parts 10 c are formed to be gradually inclined outward in the radial direction of the disk and bent back in curved forms along extended directions thereof.

In the inner side pieces 10 f , ribs 10 n protruding outward in the radial direction of the disk are respectively formed so as to support the pad resilient parts 10 c . The ribs 10 n are provided in the directions parallel to the axis of the disk and formed to have the same height of protrusion over an entire length. Further, in the sides of the outer side pieces 10 g and 10 g and the interior pieces 10 h and 10 h opposite to the disk rotor, insert guide pieces 10 p are respectively provided to be opened outward so that the lug pieces 6 b of the friction pad 6 may be easily inserted.

The pad retainer 10 formed as described above is attached to the caliper support arms 3 a by inserting the attaching pieces 10 d and the outer side pieces 10 g to the pad retainer attaching parts 3 i . In the attachment, the pad retainer 10 is attached to the caliper support arms 3 a under a state that the inner side pieces 10 f and the outer side pieces 10 g of the retainer parts 10 a respectively abut on the inner side surfaces 3 f in the radial direction of the disk and the outer side surfaces 3 e in the radial direction of the disk of the pad guide grooves 3 d respectively. Further, the elastic loop parts 10 b are respectively arranged in the sides of the caliper arms 3 a opposite to the disk rotor and the pad resilient parts 10 c are respectively arranged so that the pad resilient parts 10 c are gradually curved and inclined toward the outer side surfaces 3 e of the pad guide grooves 3 d in the radial direction of the disk toward the disk rotor from the elastic loop parts 10 b.

Further, since spaces are formed between the groove opening side parts 10 k of the outer side pieces 10 g and the outer side surfaces 3 e of the pad guide grooves 3 d in the radial direction of the disk by the stepped parts 10 m formed in the outer side pieces 10 g , as shown in FIG. 7 , a force directed outward in the radial direction of the disk is applied to the groove opening side parts 10 k of the outer side pieces 10 g by the elastic restoring force of the attaching pieces 10 d . Thus, the pad retainer attaching parts 3 i are held at three positions including groove interior side abutting parts A 1 of the groove interior parts 10 i abutting on the outer side surfaces 3 e in the radial direction of the disk, groove opening side abutting parts A 2 of the groove opening side parts 10 k and attaching piece side abutting parts A 3 of the attaching pieces 10 d abutting on the attaching surfaces 3 h between the groove interior side abutting parts A 1 and the groove opening side abutting parts A 2 in the circumferential direction of the disk. This force acts on the interior pieces 10 h so that the inner sides of the interior pieces 10 h in the radial direction of the disk are inclined toward the central parts of the friction pad 6 .

The friction pads 6 are respectively attached by inserting the lug pieces 6 b and 6 b of the back plates 6 a into the pad guide grooves 3 d and 3 d in the disk come-in side and the disk come-out side, allowing the outer side surfaces of the lug pieces 6 b and 6 b in the radial direction of the disk to abut on the outer side pieces 10 g and 10 g of the retainer parts 10 a and 10 a , allowing the inner side surfaces of the lug pieces 6 b and 6 b to abut on the pad resilient parts 10 c . Thus, in the inner side pieces 10 f and 10 f and the pad resilient parts 10 c and 10 c , slight spaces are formed between the ribs 10 n and 10 n and the pad resilient parts 10 c and 10 c , or the ribs 10 n and 10 n abut on the pad resilient parts 10 c and 10 c . Further, by the above-described attachment, the elastic loop parts 10 b and 10 b are arranged in the sides of the lug pieces 6 b and 6 b opposite to the disk rotor to prevent the friction pads 6 from slipping out. Further, the interior pieces 10 h and 10 h arranged under a state that the inner sides of the interior pieces 10 h and 10 h in the radial direction of the disk are inclined toward the central parts of the friction pads 6 are pressed by the lug pieces 6 b and 6 b to be elastically deformed toward the opposed surfaces 3 g.

The present exemplary embodiment is formed as described above. When working fluid whose pressure is raised is supplied to the hydraulic chamber 9 by a braking operation of a driver, the piston 8 moves forward in the cylinder hole 7 to press the friction pad 6 in the action part 5 a to one side surface of the disk rotor 2 rotating in the direction shown by the arrow mark A. Then, the caliper body 5 is guided by the slide pins 4 and 4 to move to the action part 5 a by a reaction force. A reaction pawl 5 e presses the friction pad 6 in the reaction part 5 b side to the other side surface of the disk rotor.

At this time, the lug pieces 6 b and 6 b of the friction pads 6 are respectively smoothly moved in the pad guide grooves 3 d and 3 d in such a way that the outer side surfaces of the lug pieces 6 b and 6 b in the radial direction of the disk are respectively guided by the outer side pieces 10 g and 10 g of the retainer parts 10 a and 10 a and the inner side surfaces of the lug pieces 6 b and 6 b in the radial direction of the disk press the pad resilient parts 10 c and 10 c to the inner side pieces 10 f and 10 f . Though the pad resilient parts 10 c and 10 c are pressed to the inner side pieces 10 f and 10 f by the lug pieces 6 b and 6 b , the resilient force of the elastic loop parts 10 b and 10 b and the pad resilient parts 10 c and 10 c press the inner side surfaces of the lug pieces 6 b and 6 b toward the outer side surfaces 3 e and 3 e of the pad guide grooves 3 d and 3 d in the radial direction of the disk.

Thus, since the outer side surfaces of the lug pieces 6 b and 6 b in the radial direction of the disk are constantly pressed to the outer side surfaces 3 e and 3 e of the pad guide grooves 3 d and 3 d in the radial direction of the disk through the outer side pieces 10 g and 10 g , the lug pieces 6 b and 6 b do not rattle in the pad guide grooves 3 d and 3 d during the braking operation. Accordingly, the striking noise of the friction pads due to the rattle can be suppressed and brake noise can be effectively suppressed.

Further, when a vibration larger than an ordinary vibration is applied to a vehicle body, for instance, when the vehicle gets over a stepped part during the driving, since the friction pads 6 respectively temporarily move inside in the radial direction of the disk against the urging force of the pad resilient parts 10 c and 10 c , and then, are urged outside in the radial direction of the disk by the urging force of the pad resilient parts 10 c and 10 c , the lug pieces 6 b and 6 b are apt to collide with the outer side surfaces 3 e and 3 e of the pad guide grooves 3 d and 3 d in the radial direction of the disk through the outer side pieces 10 g and 10 g of the pad retainer 10 . However, since the spaces are formed between the groove interior side abutting parts A 1 and the groove opening side abutting parts A 2 by the stepped parts 10 m formed in the outer side pieces 10 g , the outer side pieces 10 g can be elastically deformed to absorb the force of the lug pieces 6 b and 6 b in the direction of collision and prevent the generation of cronk noise.

Further, since the ribs 10 n and 10 n that support the pad resilient parts 10 c and 10 c are formed in the inner side pieces 10 f and 10 f , smaller spaces can be formed than a case that the spaces between the ribs 10 n and 10 n and the pad resilient parts 10 c and 10 c are eliminated or the ribs 10 n and 10 n are not provided. Accordingly, the friction pads 6 are respectively hardly vibrated in the radial direction of the disk and the cronk noise can be prevented from occurring. Further, when there is a smaller space than that of the above-described case between the ribs 10 n and 10 n and the pad resilient parts 10 c and 10 c , even if the friction pads 6 respectively move inside in the radial direction of the disk brake due to the vibration, the inner side pieces 10 f and 10 f do not abut on the pad resilient parts 10 c and 10 c . Thus, an impact is damped that the lug pieces 6 b and 6 b collide with the inner side surfaces 3 f and 3 f of the pad guide grooves 3 d and 3 d in the radial direction of the disk through the inner side pieces 10 f and 10 f and the pad resilient parts 10 c and 10 c and the generation of the cronk noise can be suppressed.

Further, since the ribs 10 n are provided in the directions parallel to the axis of the disk and formed to have the same height of protrusion over the entire length, even if the linings 6 c of the friction pads 6 are respectively worn so that the positions of the friction pads 6 are moved to the disk rotor side, a state can be maintained that only smaller spaces are formed than the case in which the spaces between the ribs 10 n and 10 n and the pad resilient parts 10 c and 10 c are eliminated or the ribs 10 n and 10 n are not provided. Accordingly, even when the lining 6 c are worn, the generation of the cronk noise can be suppressed.

Further, the lug pieces 6 b and 6 b are urged toward the opposed pad guide grooves 3 d and 3 d by the interior pieces 10 h and 10 h of the pad retainer 10 which are arranged under a state that the inner sides of the interior pieces 10 h and 10 h in the radial direction of the disk are inclined toward the central parts of the friction pads 6 and are elastically deformed by the lug pieces 6 b and 6 b . Even when a force moving in the circumferential direction of the disk is applied to the friction pads 6 respectively, for instance, when a forward movement of the vehicle is changed to a backward movement, the lug pieces 6 b and 6 b can be restrained from colliding with the opposed surfaces 3 g and 3 g of the pad guide grooves 3 d and 3 d through the interior pieces 10 h and n 10 h and the generation of the crank noise can be prevented. In such a way, even when the vibration larger than the ordinary vibration is generated in the vehicle body, the force of the lug pieces 6 b in the direction of collision can be absorbed by the pad retainer 10 and the generation of the cronk noise can be suppressed. Especially, since the generation of the cronk noise can be suppressed only by a simple structure that the stepped parts 10 m are merely provided in the outer side pieces 10 g and 10 g and the ribs 10 n and 10 n are merely provided in the inner side pieces 10 f and 10 f , there is no fear that the cost is increased.

When the above-described braking operation is cancelled to move the piston 8 and the reaction pawl 5 e backward to positions before the braking operation is started, since the elastic loops 10 b and 10 b and the pad resilient parts 10 c and 10 c are apt to return to initial forms, the lug pieces 6 b and 6 b abutting on the pad resilient parts 10 c and 10 c are respectively pressed toward the sides opposite to the disk rotor and forcedly separated from the side surfaces of the disk rotor 2 . Thus, the friction pads 6 can be respectively prevented from being dragged, judder arising due to the abrasion of the disk rotor 2 can be suppressed or brake noise can be effectively suppressed.

Further, when the linings 6 c of the friction pads 6 are worn, since the friction pads 6 gradually move forward to the disk rotor 2 side and the lug pieces 6 b and 6 b abut on the end sides of the pad resilient parts 10 c and 10 c , a resilient force from the elastic loop parts 10 b and 10 b is lowered. However, since the pad resilient parts 10 c and 10 c are curved and bent back along the extending directions, the lowered resilient force can be compensated for. Irrespective of the worn state of the linings 6 c , the friction pads 6 c can be assuredly separated from the side surfaces of the disk rotor 2 and the backlash of the friction pads can be suppressed.

Further, the friction pads 6 are temporarily attached to the caliper support arms 3 a and 3 a of the caliper bracket 3 , the elastic loop parts 10 b and 10 b are arranged in the sides of the lug pieces 6 b and 6 b opposite to the disk rotor. Thus, even when the lug pieces 6 b and 6 b are pressed to the side opposite to the disk rotor by the pad resilient parts 10 c and 10 c , since the elastic loop parts 10 b and 10 b abut on the sides of the lug pieces 6 b and 6 b opposite to the disk, the friction pads 6 can be prevented from slipping out from the caliper bracket 3 and the attaching performance of the friction pads 6 can be improved.

FIGS. 8 to 10 show other exemplary embodiments of the present invention. The same components as those of the first exemplary embodiment are designated by the same reference numerals and a detailed explanation thereof is omitted.

FIG. 8 shows a second exemplary embodiment of the present invention. Retainer parts 10 a of a pad retainer 20 of this exemplary embodiment respectively include inner side pieces 10 f and outer side pieces 10 g that face inside and outside in the radial direction of a disk with lug pieces 6 b of friction pads 6 sandwiched between them and interior pieces 20 a that connect both the pieces 10 f and 10 g in interior parts of pad guide grooves 3 d and 3 d . The interior pieces 20 a are connected to the outer side pieces 10 g at acute angles α thereto.

When the pad retainer 20 is attached to caliper support arms 3 a by inserting attaching pieces 10 d and the outer side pieces 10 g to pad retainer attaching parts 3 i , as in the first exemplary embodiment, a force directed outward in the radial direction of the disk is applied to groove opening side parts 10 k of the outer side pieces 10 g by the elastic restoring force of the attaching pieces 10 d . Thus, the pad retainer attaching parts 3 i are held at three positions including groove interior side abutting parts A 1 of groove interior parts 10 i abutting on outer side surfaces 3 e in the radial direction of the disk, groove opening side abutting parts A 2 of the groove opening side parts 10 k and attaching piece side abutting parts A 3 of the attaching pieces 10 d abutting on attaching surfaces 3 h between the groove interior side abutting parts A 1 and the groove opening side abutting parts A 2 in the circumferential direction of the disk. Since this force acts on the interior pieces 20 a and the interior pieces 20 a are connected to the outer side pieces 10 g at the acute angles α thereto, the inner sides of the interior pieces 20 a in the radial direction of the disk are greatly inclined toward the central parts of the friction pads 6 . Thus, an urging force can be increased that urges the lug pieces 6 b and 6 b toward the opposed pad guide grooves.

FIG. 9 and FIG. 10 show a third exemplary embodiment of the present invention. Since a pad retainer 30 of this exemplary embodiment does not have a mechanism for forcedly separating friction pads 6 respectively from side surfaces of a disk rotor 2 when a braking operation is cancelled, inner end sides of inner side pieces 30 a extended from inner end parts of interior pieces 10 h in the radial direction of a disk are gradually inclined outward in the radial direction of the disk to form pad resilient parts 30 b.

The present invention is not limited to an example that the impact suppressing parts are formed with the stepped parts provided in the outer side pieces of the pad retainer as described in the exemplary embodiments, and any of the impact suppressing parts such as ribs or protrusions may be used that can absorb the force of the lug pieces in the direction of collision. Further, the forms of connecting pieces or attaching pieces or the forms of insert guide pieces or the positions where the insert guide pieces are formed are arbitrary. The ribs formed in the inner side pieces may be displaced a plurality of protrusions. Further, the interior pieces may abut on the opposed surfaces of the pad guide grooves. The ribs for supporting the pad resilient parts may not be provided in the inner side pieces.