Abstract:
A spacer is disclosed which is made of a metal and interposed between opposed faces of two members having respective bores co-axial with each other and fastened to each other by inserting a fastening member into the bores and tightening the fastening member. The spacer includes a base interposed between the opposed faces of the members and having a through hole co-axial with the bores of the respective members so that the fastening member is inserted through the hole, and a temporarily retaining portion provided on an open edge of the hole of the base for temporarily retaining the overall spacer on one of the members before the members are fastened to each other, the temporarily retaining portion being inserted into the bore of the one member and caught on a wall defining the bore.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a spacer interposed between two members, and more particularly to a spacer interposed between a caliper and a steeling knuckle of a disk brake for vehicles. 
     2. Description of the Related Art 
     Disk brakes are known as a brake system of vehicles or the like. For example, JP-A-9-303440 discloses one of conventional disk brakes.  FIG. 18  illustrates one of the conventional disk brakes and  FIG. 19  illustrates a spacer used in the disk brake. The shown disk brake comprises a caliper  1  accommodating brake pads and a brake disk  9  against which the brake pads are pressed at opposed sides so as to slidingly hold the disk therebetween, whereby a braking force is effected. The caliper  1  has a mounting bore and a steeling knuckle  4  provided at the vehicle side also has a mounting bore co-axial with the bore of the caliper. A bolt  3  is screwed into the mounting bores of the caliper  1  and steeling knuckle  4  so that the caliper is mounted on the steeling knuckle. Either one of the caliper  1  and the steeling knuckle  4  is made of a metallic material, whereas the other is made of an aluminum material. Accordingly, connected portions of the caliper  1  and steeling knuckle  4  are corroded by the electrochemical reaction. For the purpose of preventing the corrosion, a spacer  5  serving as an electrolytic corrosion preventing member is interposed between the caliper  1  and the steeling knuckle  4 . 
     The spacer  5  comprises a generally ring-shaped body  6  having two claws  7  and a temporarily retaining portion  8  formed on a outer peripheral edge of the body. The caliper  1  includes amounting portion  10  to which the body  6  of the spacer  5  is mounted. The mounting portion  10  is held between the claws  7 , and a distal end of the temporarily retaining portion  8  is caught on an engagement face  2  of the caliper  1  so that the caliper is held between the body  6  and the temporarily retaining portion, whereby the spacer is temporarily retained on the caliper. Subsequently, the bolt  3  is inserted into the mounting holes of the caliper  1  and steeling knuckle  4  and tightened up so that the caliper and the steeling knuckle are tightened against the spacer. 
     In the above-described spacer  5 , however, the claw  7  and temporarily retaining portion  8  are exposed outside. Accordingly, foreign matter tends to be brought into contact with the claw  7  and the temporarily retaining portion  8  when the spacer  5  is temporarily retained on the caliper  1 . As a result, the foreign matter sometimes releases the spacer  5  from the temporarily retained state or deforms the claw  7  and the temporarily retaining portion  8 . 
     Furthermore, the claw  7  and the temporarily retaining portion  8  are formed on the outer peripheral edge of the body  6 . This renders a developed form of the spacer  5  large and accordingly reduces the material yield. 
     Additionally, in order that the spacer  5  may be mounted to the caliper  5 , the body  6  of the spacer  5  is placed opposite the mounting portion  10  of the caliper  1 . In this state, the claw  7  is caused to engage the mounting portion  10  while the body  6  is pulled downward so that the temporarily retaining portion  8  is kept opened. Subsequently, the temporarily retaining portion  8  is pressed against the surface of the caliper  1  so as to be engaged with the engagement face  2 . Thus, the mounting work is troublesome. Accordingly, the mounting of the spacer  5  cannot easily be automatized. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a spacer which can reliably be held in the temporarily retained state and has an improved material yield. 
     The present invention provides a spacer made of a metal and interposed between opposed faces of two members having respective bores co-axial with each other and fastened to each other by inserting a fastening member into the bores and tightening the fastening member, the spacer comprising a base interposed between the opposed faces of the members and having a through hole co-axial with the bores of the respective members so that the fastening member is inserted through the hole, and a temporarily retaining portion provided on an open edge of the hole of the base for temporarily retaining the overall spacer on one of the members before the members are fastened to each other, the temporarily retaining portion being inserted into the bore of said one member and caught on a wall defining the bore. 
     The above-described spacer is firstly temporarily retained on a first one of the members. In this case, when inserted into the bore of the first member, the temporarily retaining portion is flexed to elastically engage the inner wall of the bore of the first member, whereby the spacer is temporarily retained on the first member. 
     Suppose now the case where a central axis of the through hole of the spacer is slightly deviated from central axes of the bores when the temporarily retaining portion has been inserted in the bore of the first member. Even in this case, an edge of the temporarily retaining portion slides on the open edge of the bore of the first member. Consequently, the temporarily retaining portion can smoothly be inserted into the bore of the first member. 
     After the spacer has completely been mounted to the first member for the temporary retainment, the other or second member is placed on the first member with the spacer and then, the mounting member is inserted through the bore of the second member and the hole of the spacer into the bore of the first member, whereupon the three members are fixed together. 
     Since the temporarily retaining portion of the spacer is formed on the open edge of the spacer, it is located inside the bore of the first member when the spacer has temporarily been retained on the first member. Consequently, foreign matter can be prevented from coming into contact with the temporarily retaining portion as compared with the conventional spacer with the externally exposed temporarily retaining portion. Accordingly, the spacer can be prevented from being released from the temporarily retained state and the temporarily retaining portion can be prevented from being deformed. 
     Furthermore, since the temporarily retaining portion is provided on the open edge of the hole of the spacer, the material yield can be improved in the foregoing spacer as compared with the conventional spacer in which the temporarily retaining portion is provided on the outer peripheral edge of the base thereof. Additionally, since the spacer is easily fastened to the first member when the temporarily retaining portion is just inserted into the bore of the first member. Thus, the spacer mounting work can be automatized easily. 
     In one preferred form, the temporarily retaining portion has a falling-off preventing claw formed thereon by cutting a part thereof and raising the cut part, so as to be engaged with the wall of the bore of said one member. The temporarily retaining portion elastically contacts the open edge of the bore of the first member when having been inserted into the hole. With this, the falling-off preventing claw engages the inner wall of the bore of the first member. Consequently, the temporarily retaining portion can further be prevented from falling off in a disengaging direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and advantages of the present invention will become clear upon reviewing the following description of the embodiment, made with reference to the accompanying drawings, in which: 
         FIG. 1  is an exploded sectional view of a caliper, a steeling knuckle, a bolt and the spacer in accordance with an embodiment of the present invention; 
         FIG. 2  is a sectional view of the steeling knuckle, spacer and caliper in the assembled state; 
         FIG. 3  is a plan view of the spacer; 
         FIG. 4  is a side view of the spacer; 
         FIG. 5  is a plan view of the temporarily retaining portion, showing a developed form and bent state; 
         FIG. 6  is an enlarged perspective view of the temporarily retaining portion; 
         FIG. 7  is a sectional view showing the temporarily retaining portion inserted in a non-threaded portion; 
         FIG. 8  is a plan view of the spacer in accordance with a second embodiment of the invention; 
         FIG. 9  is a side view of the spacer; 
         FIG. 10  is a plan view of the temporarily retaining portion, showing a developed form and bent state; 
         FIG. 11  illustrates the guide edge of the temporarily retaining portion in the sliding contact with the tapered face of the non-threaded portion; 
         FIG. 12  is a sectional view showing the temporarily retaining portion inserted in a non-threaded portion; 
         FIG. 13  is a plan view of the spacer in accordance with a third embodiment of the invention; 
         FIG. 14  is side view of the spacer; 
         FIG. 15  is a plan view of the temporarily retaining portion, showing a developed form and bent state; 
         FIG. 16  is an enlarged perspective view of the temporarily retaining portion; 
         FIG. 17  is a sectional view showing the provisional engaging portion inserted in a non-threaded portion; 
         FIG. 18  is a partial sectional view of a conventional disk brake; and 
         FIG. 19  is a perspective view of a conventional spacer. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will be described with reference to  FIGS. 1 to 7 . A spacer  20  in accordance with the embodiment is applied to the disk brake of a vehicle, for example, an automobile. The disk brake has the same construction as described with reference to  FIG. 18 . Referring to  FIGS. 1 and 2 , the disk brake includes a disk rotated with wheels of the automobile. The disk is fastened by brake pads pressed by pistons, so that a braking force is effected. 
     Principal components such as the disk and pistons are accommodated in a caliper  14  serving as a first member. The caliper  14  is made of a material containing aluminum and mounted on a steeling knuckle  12  which is a non-rotating portion of the automobile. The steeling knuckle  12  is made of a material containing iron and serves as a second member. The caliper  14  is mounted on the steeling knuckle  12  by a bolt  11  serving as a fastening member. 
     Referring to  FIGS. 1 and 2 , the steeling knuckle  12  has a through bore  13  through which the bolt  11  is inserted. The caliper  14  also has a through bore  15  which is co-axial with the bore  13  of the steeling knuckle  12  when the steeling knuckle has been fastened to the caliper. The bore  15  includes an on-threaded portion  17  having no thread and a threaded portion  16  located below the non-threaded portion and having a thread. The non-threaded portion  17  has a slightly larger diameter than the threaded portion  16 . The non-threaded portion  17  has a reverse tapered open end. 
     A spacer  20  in accordance with the embodiment of the invention is interposed between the caliper  14  and the steeling knuckle  12 . The spacer  20  is made of mild steel, a metallic material for a spring or the like and has a surface to which an insulating coating is applied. The spacer  20  includes a generally disk-shaped base  21  and a temporarily retaining portion  24  for temporarily retaining the overall spacer  20  on the caliper  14 , as shown in  FIGS. 3 to 7 . The base  21  has a central through hole  22  which has a diameter equal to or slightly larger than the non-threaded portion  17  of the bore  15 . The bolt  11  is allowed to be inserted through the bore  13 , the hole  22  and the bore  15  sequentially when the spacer  20  is interposed between the steeling knuckle  12  and the caliper  14 . 
     The temporarily retaining portion  24  will now be described. Three temporarily retaining portions  24  are provided at regular intervals on the open edge of the hole  22  as shown in  FIGS. 3 and 4 . Each temporarily retaining portion  24  is bent at the open edge of the hole  22  toward the caliper  14  side into a generally L-shape and is flexible radially. Each temporarily retaining portion  24  flexibly contacts a circumferential wall defining the non-threaded portion  17  of the bore  15  as will be described later. However, the temporarily retaining portion  24  is formed so as not to be brought into contact with the bolt  11  when the bolt is inserted through bore  13 , the hole  22  and the bore  15  sequentially. 
     Each temporarily retaining portion  24  includes a root portion and two slits  23  formed in both sides of the root portion so as to extend radially outward with respect to the base  21 , respectively, as shown in  FIG. 3 . The slits  23  serve to enhance the flexibility of each temporarily retaining portion  24 . In bending each temporarily retaining portion  24 , the root portion thereof is firstly caused to project horizontally from the base  21  as shown in  FIG. 5  and thereafter bent substantially vertically. Furthermore, each temporarily retaining portion  24  has a pair of projections  25  formed on respective opposite sides of a distal end thereof so that the projections extend symmetrically generally in a circumferential direction of the hole  22 , as shown in  FIGS. 4 to 7 . Each projection  25  has two tapered guide edges formed on both side edges of a distal end thereof respectively. As a result, each temporarily retaining portion  24  is generally formed into the shape of a tapered arrowhead. Consequently, even when a central axis of the hole  22  is slightly deviated from a central axis of the non-threaded portion  17  in insertion of each temporarily retaining portion  24  into the non-threaded portion, the guide edges  26  are brought into a sliding contact with the open edge of non-threaded portion  17  or the tapered portion  18 , whereby each temporarily retaining portion  24  is self-aligned. Consequently, each temporarily retaining portion  24  can smoothly be inserted into the non-threaded portion  17 . Additionally, each projection  25  is flexibly contacted with the inner circumferential wall of the non-threaded portion  17  along the curved wall surface. 
     Each temporarily retaining portion  24  has a generally triangular falling-off preventing claw  27  formed in a width wise central portion thereof. Each falling-off preventing claw  27  is formed by cutting a part of each temporarily retaining portion  24  and raising the cut part outward into a cantilevered shape. Accordingly, each temporarily retaining portion  24  has an end at the side toward which the retainer comes out of the non-threaded portion  17  of the bore  15 . The end serves as a flexible free end. The free end is adapted to abut the inner circumferential wall of the non-threaded portion  17  when each temporarily retaining portion  24  is inserted into the non-threaded portion. Furthermore, a distal end of the free end is pointed so that each temporarily retaining portion is enhanced to bite into the inner circumferential wall of the non-threaded portion. 
     In order that the spacer  20  may be temporarily retained on the caliper  14 , each temporarily retaining portion  24  is thrust into the non-threaded portion  17  until it reaches a position where the base  21  adheres closely to the outer face of the caliper  14 , as shown in  FIG. 2 . 
     After insertion of the temporarily retaining portions  24 , the projections  25  elastically contacts the inner circumferential wall of the non-threaded portion  17 , and the falling-off preventing claws  27  engage the wall so as to bite into the wall. As a result, the spacer  20  is temporarily held on the caliper  14  and prevented from easily falling off. 
     Subsequently, the bolt  11  is inserted into the bore  13 , the hole  22  and the bore  15  sequentially and tightened up while the spacer  20  is in abutment with the steeling knuckle  12 , whereby the fixing of the steeling knuckle  12 , spacer  20  and caliper  14  is completed. 
     In the above-described embodiment, the spacer  20  renders the temporary holding on the caliper  14  reliable, and the temporarily retaining portions  24  are formed on the open edge of the hole  22  of the base  21  and engage the inner circumferential wall in the non-threaded portion  17 . Thus, since the temporarily retaining portions  24  are not exposed externally, foreign matter can be prevented from coming into contact with the temporarily retaining portions  24  as compared with the conventional spacer with the externally exposed temporarily retaining portion. Consequently, the spacer  20  can be prevented from an inadvertent release from the temporarily held state, and the temporarily retaining portion  24  can be prevented from deformation. 
     Furthermore, since the temporarily retaining portions  24  are formed on the open edge of the hole  22 , the developed form of the spacer  20  can be rendered smaller and accordingly, the material yield can be improved as compared with the case where the temporarily retaining portions  24  are provided on the outer peripheral edge of the base  21 . 
       FIGS. 8 to 12  illustrate a second embodiment of the invention. In the above-described first embodiment, the guide edge  26  which is a guiding structure is formed at the stage where the temporarily retaining portion  24  is stamped out. In the second embodiment, however, the guiding structure is formed at a bending step after the stamping. 
     More specifically, in the first embodiment, the distal end of each projection  25  is cut into a tapered shape so that the guide edge  26  is formed when the temporarily retaining portion is in the developed form in the stamping. Accordingly, the temporarily retaining portion  24  is formed generally into the shape of an arrowhead. 
     On the other hand, in the second embodiment, the distal edges of both projections  31  extend from the distal edge of a main part  33  of the temporarily retaining portion  30  so as to be co-planar with the distal edge of the main part. In other words, the distal end of the temporarily retaining portion  30  is extended horizontally but not tapered. 
     However, when both projections  31  are bent inward along an inclined bending edge  34 , the level of the distal edges of both projections  31  is higher than the level of the distal edge of the main part  33  as shown in  FIGS. 9 and 11 . Furthermore, the distal edge of each projection  31  is continuous to the distal edge of the main part  33  at an angle α as shown in  FIG. 9 . Thus, the distal edge of each projection  31  can serve as the guide edge  32  in the case where the temporarily retaining portion  30  is inserted into the non-threaded portion  17  of the bore. 
     Furthermore, since the guide edge  32  is formed by bending the projection  31 , the strength of each projection  31  can be improved as compared with the case where the distal edge of each projection  25  is cut into the tapered shape as in the first embodiment. 
     The other structure of the spacer in the second embodiment is the same as that in the first embodiment and accordingly, the same effect can be achieved from the second embodiment as from the first embodiment. Accordingly, the description of the other structure is eliminated. 
       FIGS. 13 to 17  illustrate a third embodiment of the invention. The falling-off preventing claws  27  are eliminated in the third embodiment although provided in the first and second embodiments. The projections  36  of each temporarily retaining portion  35  are bent radially outward at the root portions of the projections. When each temporarily retaining portion  35  is inserted into the non-threaded portion  17 , the edge of a side edge corner  37  of each projection  36  abuts the inner circumferential wall of the non-threaded portion  17 . 
     Accordingly, when each temporarily retaining portion  35  is inserted into the non-threaded portion  17 , each temporarily retaining portion  35  is elastically deformed radially inward to be thrust into the non-threaded portion while the corners  37  of the projections  36  are in contact with the inner circumferential wall of the non-threaded portion  17  (see  FIGS. 15 and 17 ). When having been inserted in the non-threaded portion  17 , the temporarily retaining portions  35  elastically contact the inner circumferential wall of the non-threaded portion  17 , and the corners  37  bite into the inner circumferential wall of the non-threaded portion  17 . Consequently, each temporarily retaining portion  35  can be prevented from falling off. 
     In the third embodiment, an effective means for falling off from the caliper can be provided even when no falling-off preventing claws are provided. Consequently, a step of forming the falling-off preventing claws can be eliminated. 
     The other structure of the spacer in the third embodiment is the same as that in the first embodiment and accordingly, the same effect can be achieved from the third embodiment as from the first embodiment. Accordingly, the description of the other structure is eliminated. 
     Modified forms of the foregoing embodiments will be described. In the above-described embodiments, the spacer  20  is interposed between the steeling knuckle  12  and caliper  14  of the disc brake. However, the spacer may be interposed between other two members, instead. 
     In the foregoing embodiments, the caliper  14  is made of a metal and is discrete from the spacer  20 . For example, however, the spacer may be temporarily retained on a resin fastening member and may be formed integrally with the fastening member by an insert molding, instead. 
     Each falling-off preventing claw  27  is made by cutting a part of each temporarily retaining portion and raising the cut part in the first and second embodiments. However, any claw-shaped projection protruding to the outer face side of the temporarily retaining portion may be provided, instead. 
     The foregoing description and drawings are merely illustrative of the principles of the present invention and are not to be construed in a limiting sense. Various changes and modifications will become apparent to those of ordinary skill in the art. All such changes and modifications are seen to fall within the scope of the invention as defined by the appended claims.