Abstract:
A brake calliper has two arms, each including a housing and a stub. A member for guiding a disc brake pad is disposed in the housing, and is secured by lugs to a front of the stub. The member includes a body having a U-shaped section formed by an inner radial surface, a base, an outer radial surface, and includes a tongue that extends beyond an edge of the body, and that is configured to be hooked in the housing and to fully lock the member in the arm. An inner side of the body is bordered by an inner front supporting surface disposed against an inner surface of the arm. An outer front supporting surface is disposed against the front of the stud, extends into a hairpin damper spring extending towards the front of the stud, and is bordered on each side by a tongue that form side end-stops.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2012/075602, filed on Dec. 14, 2012, which claims the benefit of priority to Serial No. FR 1103876, filed on Dec. 15, 2011 in France, the disclosures of which are incorporated herein by reference in their entirety. 
     The present disclosure relates to a guiding member for a disk brake pad in a cap which is composed of two U-like arms connected by two bars, each arm having at the two ends thereof an axial housing which has a substantially rectangular cross-section and which is bounded by a base, an internal radial surface and an external radial surface and above the housing,
         the guiding member being formed by a spring steel band which is folded in order to be fixed to the stud and which is positioned in the housing of the arm and to receive in an axially sliding manner the corresponding lug of the pad, the lug being provided with a radial spring in order to be guided and pressed by the guiding member and the housing.       

     Such a guiding member of a brake pad in the housing of a cap of a disk brake makes it easier to displace the brake pad during braking. 
     The disclosure also relates to a disk brake provided with such guiding members according to disclosure. 
     BACKGROUND 
     In a vehicle provided with disk brakes, each wheel to be braked comprises a brake disk which is fixedly joined to the wheel and brake pads which are fixedly joined to the chassis of the vehicle and which brake the disk by friction. The brake comprises a calliper having a cap having at each side of the brake disk a U-like branch which carries a brake pad and each pad is movable perpendicularly relative to the plane of the disk, in a state guided by the two ends (lugs) thereof in the housings of the arms of the cap. 
     During braking, the pads are moved in the direction tangential to the disk and the lugs move into abutment, sometimes abruptly, against the bottom of their guiding housing, thereby bringing about a noise referred to as a “clonk” or tapping. In order to damp the impact of the lugs in their housing and thereby to attenuate the noise, there is provided a spring between each lug and the housing thereof and the damping is obtained by the deformation of the spring whose shape is adapted to the force applied by the brake pad during its tangential displacement. 
     Furthermore, the pad must be able to move axially by its lugs sliding in the retention spring which combines a function as a slide and a function as a spring. 
     Once the pad is in position, the slide system becomes deformed as a result of the geometric defects and the spring effect and brings about a spring/rigidity effect which has an influence on the generation of noise during the braking. 
     Such guiding members for disk brake pads are already known according to the documents WO 01/31223 and FR 07 09 124. 
     SUMMARY 
     An object of the present disclosure is to improve such guiding members for disk brakes in order to improve their efficiency and to reduce the noise during braking. 
     To this end, the disclosure relates to a guiding member of the type defined above, characterized by
         a body which has a cross-section in the form of a U on its side and which is substantially rectangular in order to be positioned in the housing and which is continued by   a front abutment surface which moves into abutment against the front surface of the stud and which carries two tongues in order to form lateral stops which extend at one side and the other of the stud and a hairpin-like shock-absorbing spring which moves toward the front in order to resiliently press against the side of the pad above the lug, and by   a front internal abutment surface which moves into abutment against the internal surface of the arm and which receives the face of the pad under the lug,   the body having an external radial surface which moves into abutment against the upper surface of the housing, followed by a base which moves into abutment against the base of the housing and an internal radial surface which is provided with a locking tongue in order to press against and become engaged with the lower surface of the housing.       

     The guiding member according to the disclosure is excellently fixed to the arm of the cap both by being retained on the stud and by being engaged by means of the locking tongue in the housing of the arm. The U-like form of the body of the guiding member provides good guiding contact for the auxiliary spring or radial spring with which each lug of the pad is provided and which promotes not only the sensitivity of the braking movement but especially the clearance of the pad with respect to the surface of the disk at the end of braking in order to prevent any residual contact, which is a source of losses owing to friction. 
     The shock-absorbing spring applies a moderate force which pushes the brake pad into abutment against the downstream support thereof in the direction of rotation of the brake disk and with zero play which prevents any noise during braking. 
     At the upstream side, the play is at a maximum. 
     The force applied to the shock-absorbing spring is independent of the other actions applied to the guiding member. It is also necessary to emphasise that the reaction on the shock-absorbing spring varies weakly during the wear of the linings of the pads. 
     The guiding member according to the disclosure constitutes the solution which ensures both the excellent quality of the guiding of the lug of the pad and retains the pad relative to the arm of the cap in order to prevent any noise connected with an impact at the start of braking. 
     Finally, the guiding member is installed in a particularly simple manner in the housing of the arm. 
     The rounded edge against which the corresponding side of the pad presses not only ensures guiding contact which prevents any jamming, even point-like jamming, or sticking of the shock-absorbing spring on the surface of the pad, in particular for the return movement of the pad at the end of braking, which movement is particularly sensitive. Furthermore, this inwardly curved surface constitutes a complementary spring with respect to the hairpin-like shock-absorbing spring because, in the event of compression of the hairpin-like shock-absorbing spring, the rounded edge of the abutment surface will also act by means of deformation to damp the impact for a reverse rotation, with backward travel. 
     According to an advantageous feature, the two lateral stops are constituted by tongues which are cut from the metal sheet at one side and the other of the hairpin-like shock-absorbing spring and which are bent toward the stud. 
     According to another advantageous feature, the locking tongue is cut and resiliently shaped from the bottom segment and the internal segment of the body, substantially at the centre of the axial length of the band forming the guiding member. 
     This embodiment is advantageous because the whole of the guiding member is cut from a single spring steel band and is then shaped by resilient bending to a greater or lesser extent in accordance with the rigidity or resilience to be imparted to each portion of this guiding member. 
     According to an advantageous feature, the end rounded in accordance with a cylindrical shape of the hairpin-like shock-absorbing spring comprises two guiding extensions which are curved toward the rear in order to facilitate the engagement of the edge of the pad against the rounded edge of the hairpin-like shock-absorbing spring. 
     This embodiment most particularly facilitates the engagement of the pad with the two lugs thereof in the respective housing of the arm, each housing being provided with a guiding member as defined above. 
     According to another advantageous feature, the folding edge between the third segment of the body and the internal branch comprises a longitudinal cutout over a large portion of the axial length thereof, allowing the material at the ends to remain. 
     The disclosure also relates to a disk brake provided with guiding members as defined above and more particularly a disk brake whose housings upstream of the arms are each provided with a guiding member comprising:
         a body which has a cross-section in the form of a U on its side and which is substantially rectangular in order to be positioned in the housing of the arm of the cap and which is continued by   a front external abutment surface which moves into abutment against the front surface of the stud of the arm and which carries two tongues in order to form lateral stops which extend at one side and the other of the stud and a hairpin-like shock-absorbing spring which moves toward the front in order to resiliently press against the side of the pad above the lug, and by   a front internal abutment surface which moves into abutment against the internal surface of the arm and which receives the face of the pad under the lug,   the body having an external radial surface which moves into abutment against the upper surface of the housing, followed by a base which moves into abutment against the base of the housing and an internal radial surface which is provided with a locking tongue in order to press against and become engaged with the lower surface of the housing.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be described in greater detail below with reference to an embodiment of a guiding member of a disk brake pad according to the disclosure illustrated in the appended drawings, in which: 
         FIG. 1  is a side view of a disk brake cap which is provided with two guiding members and a brake pad, 
         FIG. 2  is a view corresponding to  FIG. 1  showing the brake pad and the cap before the brake pad is installed, 
         FIG. 3  is an isometric view of an end of the cap showing an end of each arm connected by a bar, 
         FIG. 4  is an isometric view of the guiding member according to the disclosure, 
         FIG. 5  is a side view of the member of  FIG. 4 , 
         FIG. 6  is a sectional view along A-A of the spring of  FIG. 5 , 
         FIG. 7  is a sectional view along B-B of the spring of  FIG. 5 , 
         FIG. 8  is a partial side view, drawn to an enlarged scale, of the guiding member installed in the housing of the arm with the lug and the two sides of the pad bounding the lug. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  generally shows a brake disk  1  which is straddled by a cap  2  which comprises two arms  20  connected by two bars  21 . Those two U-like arms  20  extend at one side and the other of the disk  1  and each carry a brake pad. The brake pads  3  are provided at the ends thereof with lugs  31  for being assembled in the housings  22  of each arm, by means of a guiding spring  4 ,  4 ′ with which each housing  22  is provided and which cooperates with the lug  31  of the pad, which is itself provided with an auxiliary spring  5 . 
     In order to facilitate the description, the orientation defined by the references X, Y, Z indicated in  FIG. 1  will be adopted. 
     The direction Z is the axial direction perpendicular to the plane of the Figure and parallel with the axis of the disk  1 . 
     The direction Y is the radial direction, that is to say, a direction passing through the axis of the disk, the external side and the internal side being defined in this direction. 
     The direction X corresponds to the lateral direction contained in the plane of  FIG. 1  and perpendicular to the radial direction Y. In fact, the direction X is the tangential direction, the upstream side and the downstream side corresponding to the direction of rotation of the disk. 
     The lugs  31  at the two ends of the pad  3  slide axially in the guiding springs  4 ,  4 ′, that is to say, perpendicularly to the plane of  FIG. 1 . 
     The function of the guiding springs  4 ,  4 ′ is to guide the pad for braking and the return thereof to a position out of contact with the brake disk and to damp the impact of the lugs against the base of each housing  22  when the pads  3  are carried by the disk  1  during a braking operation. The damping of the impact results from the deformation of the guiding members  4 ,  4 ′ under the force applied by the pads  3 . If the direction of rotation of the disk  1  is given by the curved arrow V which extends from right to left in accordance with  FIG. 1 , the pad  3  which is pressed against the disk  1  advances from the right to the left in the direction of the arrow V and is moved into abutment against the base of the housing  22  by the end of the front lug  31  thereof. The guiding member  4  damps this movement by means of the hairpin-like spring and reduces or prevents the impact of the lug against the base of the housing  22  downstream and consequently the noise which would result from that impact. 
       FIG. 2  is a side view of a cap  2  provided with a guiding member  4  according to the disclosure and, above the cap  2 , a brake pad  3  with, at the two lugs  31  thereof provided with radial springs  5  of wound form; those springs  5  which are arranged transversely relative to the plane of  FIG. 2  are engaged in the manner of pincers on the lugs  31 . 
       FIG. 3  is a partial isometric view of a cap  2  which shows the end of two arms  20  which are connected by the bar  21  and which allows the gap between the two arms for receiving the brake disk (not illustrated) to be seen. 
     That view shows the shape of the housing  22  bounded by a lower surface  222 , a base  221  and an upper surface  223 . The upper surface  223  is part of a stud  25  which has a front surface  251  and to which the guiding member  4  is fixed. The housing of the other arm  20  is provided with a guiding member  4  showing how the guiding member  4  is fixed to the stud  25 , and moves into the housing  22  in order to then move into abutment against the front surface under the housing  22 , the arm has an internal front surface  224 . 
       FIG. 4  shows such a guiding member  4  according to the disclosure in a non-installed position and the description makes use of the orientation conventions defined with reference to  FIG. 1  by the notions “radial”, “internal”, “external”, “lower” and “upper”. 
     The guiding member  4  is obtained by shaping a band of spring steel. It comprises a body  40  in the form of a U on its side, having a substantially rectangular cross-section with bent corners  40   a ,  40   b , comprising at one side a base  41  which continues downward by way of an internal radial surface  42  and, at the other side, by way of an external radial surface  43 . That surface continues as an external abutment surface  44  which carries, on the one hand, a hairpin-like shock-absorbing spring  45  which is directed forward and which is bounded at each side by a lateral abutment tongue  46  which is directed toward the rear. The hairpin-like shock-absorbing spring  45  and the two abutment tongues  46  are separated by a cutout  47  at each side in order, on the one hand, to conserve the entire rigidity in the abutment tongues  46  and, on the other hand, to allow the shock-absorbing spring  45  to deploy its entire resilience. 
     The shock-absorbing spring  45  terminates at the front in a rounded lower edge  48  which is directed axially and which terminates at each end in an inwardly curved guiding member  48   a  in order to make it easier to position the brake pad  3  in the housing  22  of the arm  20  of the cap  2  which is provided with such a guiding member  4 . 
     The internal abutment surface  49  is connected to the internal radial surface  42  by a cut-out fold  49   a  which extends over a large portion of the length thereof and which allows only two curved attachments  49   b  of material at the two ends to remain. 
     Finally, the internal radial surface  42  and the base  41  are provided with a locking tongue  6  which is cut out of the mass in the region of the bent corner  40   b , substantially at the center of the axial length of the guiding member  4 . This locking tongue  6  extends beyond the internal radial surface  42  in a downward direction (in accordance with the orientation of  FIG. 4 ) in order to constitute an engagement member which grips the base  221  of the housing  22 . 
     In order to promote this engagement, the front edge of the locking tongue  6  comprises two rounded portions  61  which protrude and which are separated by a recessed curved portion  62 . 
       FIG. 5  is a rear side view of the guiding member  4  of  FIG. 4  showing the arrangement of the hairpin-like shock-absorbing spring  45  which is attached to the external abutment surface  44  and the separation of the two lateral abutment tongues  46  by means of a deep cutout  47  having a rounded base so as to disengage in a dynamic manner the shock-absorbing spring  45  and the two lateral abutment tongues  46 . 
     That rear view also shows the shape of the locking tongue  6  and the cutout thereof from the base  41  and the internal radial surface  42  in such a manner as to allow the locking tongue  6  to fully deploy its resilience in order to become engaged in the housing  22  and to retain the guiding member  4  at that location by locking. 
       FIG. 6  is a cross-section of the guiding member  4  and the different component parts thereof, showing the rectangular shape of the body  40  of the guiding member and the connection of the internal radial surface  42  at right angles to the base  41  of the body by a rounded fold. The same is accordingly true of the external abutment surface  44  which extends by way of a hairpin-like shock-absorbing spring  45 , at a side, that is to say, at the front side, not directed toward the cap in which that guiding member will be positioned and, at the other side, the lateral abutments  46 . This Figure also shows the shape of the rounded edge  48  of the shock-absorbing spring  45  and the shape and the arrangement of the locking tongue  6 . 
     The cross-section of  FIG. 7  taken through the guiding member  4  in the region of the rounded lower edge  48  of the shock-absorbing spring  45  emphasises the inwardly curved shape of the two ends  48   a  of this rounded edge  48  which act as guiding surfaces in order to receive the lug  31  of the pad which is further provided with the radial spring  5  thereof ( FIG. 2 ). 
       FIG. 8  is a side view, drawn to an enlarged scale, of the arrangement of the upstream lug  31  of the pad  3 , which lug is provided with the radial spring  5  thereof and which moves into the U-like cavity of the body  40  of the guiding member  4  which is itself previously installed in the axial housing  22  of the end of the arm  20  of the cap  2 . This Figure emphasizes the positioning of the upper portion of this guiding member  4  with its external abutment surface  44  moving into abutment against the front surface  251  of the stud  25  and the two lateral abutment tongues  46  moving at one side and the other of the stud  25  and finally the hairpin-like shock-absorbing spring  45  which is curved at the side opposite the sides of the abutment tongues  46  in order to move into abutment with the rounded portion  48  thereof against the face  33  of the pad  3  above the lug  31  and to repel the pad  3  in abutment against the downstream housing of the arm in order to reduce or to eliminate any play at that location. 
     It should be noted that the arm is advantageously provided with a shock-absorbing spring  45  only in the upstream housing  22  whilst the downstream housing is provided with a guiding member without the shock-absorbing spring in order thereby to have maximum play between the housing  22  of the arm  20  and the lug  31  at the upstream side and practically zero play at the downstream side. 
     The disclosure thereby generally relates to disk brakes and automotive equipment. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  disk 
           2  cap 
           20  U-like arm 
           21  bar 
           22  housing 
           221  base 
           222  lower surface 
           223  upper surface 
           224  internal front surface 
           25  stud 
           251  front surface of stud 
           3  pad 
           31  lug 
           33  face of pad above lug 
           34  face of pad under lug 
           4  guiding member 
           4 ′ guiding member 
           40  body 
           40   a, b  corners/bends 
           41  base 
           42  internal radial surface 
           43  external radial surface 
           44  external abutment surface 
           45  shock-absorbing spring 
           46  lateral tongue 
           47  cutout 
           48  rounded lower edge 
           48   a  guiding member 
           49  internal abutment surface 
           49   a  cutout bend 
           49   b  bent attachments 
           5  axial spring 
           6  locking tongue 
           61  rounded edge 
           62  inwardly curved portion