Patent Publication Number: US-2023151858-A1

Title: Backing plate for a disk brake of a motor vehicle and method for manufacturing said backing plate

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application (under 35 USC § 371) of PCT/EP2021/055860, filed Mar. 9, 2021, which claims benefit of DE 102020106296.6, filed Mar. 9, 2020, the contents of each of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Technical Field and State of the Art 
     The invention relates to a backing plate for a disc brake of a motor vehicle. Furthermore, the invention relates to methods for manufacturing such a backing plate. 
     Backing plates for disc brakes of a motor vehicle are known in a variety of ways. Backing plates are guided and supported in such disc brake devices in a shaft of the brake caliper or the brake carrier, respectively. The backing plate is adapted to absorb a brake pressure transmitted by a brake cylinder in order to transfer said brake pressure onto the brake disc. So that the backing plate is securely held in the shaft of the brake caliper or the brake carrier, respectively, hold-down springs are provided, which often engage on the upper side of the backing plate and are pretensioned radially against the backing plate and tangentially against the backing plate by means of a hold-down device. For example, backing plates with such hold-down springs are shown in DE 10 2013 008 155A1. A wire spring fora brake shoe arrangement in a floating caliper brake is known from DE 10 351 477 B4. The wire spring therein is supported by its circular coils in a recess of a backing plate for the brake shoe in order to prevent the brake shoe from rattling on the guides in the brake jaw arrangement. 
     It is an object of the invention to provide a backing plate wherein an alternative arrangement of the spring element is provided in order to minimize the logistical effort to inventory the required parts and also to simplify the fastening of the spring element to the backing plate. Furthermore, it is an object of the invention to provide a method for producing a backing plate according to the current invention. 
     SUMMARY OF THE INVENTION 
     The backing plate according to the invention for a disc brake of a motor vehicle, in particular a commercial vehicle, comprises a front side adapted to accommodate a friction lining. The backing plate according to the invention is characterized in that the backing plate has a back side on which a mounting device is arranged, which is adapted to accommodate a spring element consisting of a spring base and two spring legs arranged at the ends of the spring base. The spring element can be formed as a wire spring. The mounting device is in this case adapted to form a substance-to-substance bond (i.e., integrally bonded) to the back side of the backing plate. In particular, as defined by the invention, an inventive backing plate can also be claimed with such a spring element. 
     It is therefore particularly advantageous for the inventive backing plate that the mounting device for accommodating the spring element is an integral part of the backing plate and is already manufactured together with the backing plate while the latter is manufactured. The mounting device is then captively held on the backing plate. Therefore, no individual elements, such as screws or holding clips, need be provided so that a mounting device for a spring element can be arranged on the back side of the backing plate. This eliminates logistical expenses to procure and store these individual parts. In addition, the processing step of joining these individual parts to the backing plate on the back side is also omitted. In contrast to backing plates on which a mounting device for a spring element can subsequently be attached to its back side by means of a threaded-in retaining clip or the like, the processing step of inserting the threads for the screws into the back side of the backing plate is also omitted. The overall manufacturing costs for the backing plate with mounting device for the spring elements can be significantly reduced by the invention. 
     The logistical effort and also the energy expense for arranging a mounting device for a spring element on the back side of a backing plate can thus be minimized by the inventive backing plate. As a result, both the economic as well as the ecological footprint of the inventive backing plate is significantly improved compared to the backing plates known from the prior art according to the preamble of claim  1 . 
     According to a first advantageous embodiment of the invention, the mounting device comprises at least one support element for the spring base and each of the two spring legs on the back side of the backing plate. This embodiment of the invention achieves that the spring is securely held in the shaft of the brake caliper or the brake carrier, respectively, when operating the backing plate in a brake system, wherein the support elements support the spring element under load such that the spring element can fulfill the desired spring function within the brake system, in particular as a hold-down spring. 
     Alternatively, only one support element can be provided for both spring legs and/or the spring base. The support element can be formed as a projection with at least one through opening or recess, similar to a hand-hold or a pocket. The support element can have two through openings, in particular bores, for inserting the spring legs. 
     The mounting device can comprise only one support element for the spring base and/or only one support element for a spring leg. According to an advantageous embodiment, this reduced mounting device comprises one or more of the subsequently described support and guide elements for stabilizing the associated spring. 
     An advantageous further embodiment of the invention provides that at least one of the support elements is formed with respect to the back side of the backing plate to have an undercut for accommodating the spring base or a spring leg of the spring element. Such undercuts once again improve the support effect and the captive positioning of the spring element within the mounting device because such undercuts grip the individual elements of the spring element, in particular the spring legs and the spring base, on multiple sides. This optimizes the captive mounting of a spring inserted in the mounting device. Such undercuts can be formed differently in this case. For example, it is conceivable that, in a particularly advantageous embodiment, the support elements have a region arranged perpendicularly on the backing plate, followed by an angular, in particular rectangular, region of the support element, which is arranged at an angle of less than 90° to the back side of the backing plate, in particular parallel to the back side of the backing plate. Another possibility of forming such undercuts is that the support elements for the spring base or the spring legs are adapted such that they have an acutely angled surface in relation to the back side of the backing plate in the region where the spring element supports itself on said support elements. The undercuts described here are particularly well suited to captively hold the spring element within the mounting device for the spring element. In principle, the undercuts can be formed such that they are adapted to the profile of the spring element. In particular, for spring elements with circular cross-sections, these undercuts can have corresponding circular segment-shaped support surfaces for the spring element. 
     The embodiment of the invention likewise specifies that the mounting device has a locking element associated with the support element for the spring base. This locking element forms a region between itself and the support element for the spring base in which the inserted spring element can be captively accommodated. This is in particular the case when the support elements of the spring legs have the undercuts described above. This achieves that a spring element is captively held in the mounting for the spring element on the back side of the backing plate in a displacement-proof manner. 
     A further advantageous embodiment of the invention provides that the mounting device has a common support and guide element for the two spring legs, wherein the mounting device is arranged on a longitudinal center axis between a backing upper side and the support elements of the two spring legs. This support element is primarily adapted such that the spring legs can under load support themselves against the support element when the backing plate is installed in a shaft of a brake caliper or a brake carrier. In addition, this support element can be adapted as a guide element when inserting the spring into the mounting device on the back side of the backing plate. While being inserted, the spring can be then guided through this support element such that this common support element of the spring legs is located between them and the spring element is now displaced such that it is guided between the support element assigned to the respective spring leg. The locking element associated with the support element of the spring base described above is then used to secure the spring within the mounting device by pushing the spring element with its spring base over this locking element. It can be provided in this case that the locking element associated with the support element for the spring base is provided with an alignment slant over which the spring element is pushed with its spring base such that the spring base is then securely held between its support element and the locking element. 
     Alternatively or in addition to the aforementioned common support and guide elements, additional elements can be provided, each of which is associated with a single spring leg. These further support and guide elements are preferably not arranged on the longitudinal center axis between the backing upper side and the support elements of the two spring legs. For example, the elements can be formed as projections with a cylindrical or polygonal cross-section and can optionally also have undercuts. A further advantageous embodiment of the invention provides that the spring legs are equipped with a support region at their open ends, with which the spring element supports itself on a support element of the disc brake system with a backing plate mounted in a disc brake system. This provides a contact region for the disc brake systems on the spring element, wherein these contact regions of the spring element are adapted to the disc brake system. 
     It is also particularly advantageous that the inventive backing plate is formed as a metal casting, preferably as an iron casting. Many of the currently used backing plates are manufactured as such iron castings. Therefore, it is not necessary to provide an entirely new manufacturing process for the casting in order to manufacture the inventive backing plate. It is sufficient to accordingly adapt the casting mold for the backing plate. Otherwise, the entire manufacturing process can remain unchanged. The use of different casting molds, which are interchanged during production, is a given anyway because different brake systems require different backing plates. 
     The inventive method for producing a previously described backing plate, in particular made of cast metal, has the following method steps:
         a. Provide an at least two-part negative mold of a backing plate that has a negative mold for the mounting device,   b. Provide a metal melt, in particular a cast iron melt,   c. Close the at least two-part negative mold of the backing plate,   d. Fill the at least two-part negative mold of the backing plate with the melt,   e. At least partially solidify the melt within the closed negative mold of the backing plate,   f. Open the negative mold of the backing plate,   g. Remove the at least partially solidified backing plate.       

     The inventive method is characterized in that the negative mold of the backing plate has a negative mold for the mounting device. By this embodiment of the invention, the mounting device is manufactured as an integral part of the casting of the backing plate without the need for subsequent joining process steps to mount a corresponding mounting device on the back side of the backing plate. 
     In order to ensure a safe positioning of the spring element within the mounting device, it is provided that at least one of the support elements for the spring base and the two spring legs is provided with an undercut. Such undercuts are preferably generated by milling out the at least one support element. The milling can be done in such a way that the shape of the undercuts is adapted to the shape or the profile or the cross-section of the spring element such that a particularly good support effect of the spring element is achieved within the mounting device when the spring element is placed under load during operation. 
     A further advantageous method step can provide that the locking element and/or the common support element for the two spring legs associated with the spring base are post-processed. In particular, an alignment slant can be incorporated in the locking element associated with the spring base, said alignment slant facilitating a secure positioning of the spring element within the mounting device when inserting the spring element into the mounting device. 
     For the reliable functioning of the backing plate and spring element within a brake system, it is lastly provided that the spring element is inserted into the mounting device. 
     Alternatively, it can also be provided that the backing plate is formed as a steel plate. For example, the backing plate may be punched out of a rolled strip steel. The mounting device can be formed by a progressive transfer process, in particular by a punching process. 
     According to an advantageous further embodiment, the mounting device on the back side of the backing plate has dimple-like projections as support elements, in particular for supporting the spring legs, which are also referred to as dimples. In the installed position, the spring legs are preferably at least in regionally resting on the dimples. 
     The dimples can for example be formed in a circular shape, but can also have other shapes. The dimples can for example be formed in a semi-circular shape, wherein the undercuts can each only point to the center of the backing plate. 
     The inventive method for producing a previously described backing plate made of steel with dimples on the back side comprises that the mounting device of the backing plate is formed with dimple-like projections projecting to the back side of the backing plate with undercuts as support elements, formed by pressing through parts of the backing plate, wherein the dimple-like projections are formed in a first step in a forming process, and that the dimple-like projections are in a second step split and formed in the opposite direction to the forming process of the first step, thus forming the undercuts. 
     A rolled strip steel can be used to manufacture the backing plate. The backing plate and/or the contour thereof can, for example, be punched out of the strip steel. 
     Further objectives, advantages, features and applications of the present invention are derived from the subsequent description of an embodiment by way of the drawings. All described and/or depicted features per se or in any combination constitute the subject matter of the present invention, regardless of their summary in the patent claims or their back-reference. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       These show in: 
         FIG.  1    a first design example of an inventive backing plate in a top view of the back side, 
         FIG.  2    the backing plate of  FIG.  1   , into which a spring element is inserted, 
         FIG.  3    the backing plate of  FIG.  1    with the spring element in its final position, 
         FIG.  4    a detailed view of the mounting device of the backing plate of  FIGS.  1  to  3   , and in 
         FIG.  5    a further detailed view of the mounting device of the backing plate of  FIGS.  1  to  3     
         FIG.  6   : a second design example of an inventive backing plate in a top view onto the back side, 
         FIG.  7    the backing plate of  FIG.  6   , into which a spring element is inserted, 
         FIG.  8    the backing plate of  FIG.  6    with the spring element in its final position, 
         FIG.  9    a third embodiment according to  FIGS.  6  to  8   , but without support element, 
         FIG.  10    a fourth design example according to  FIGS.  1  to  5   , but without a support element, 
         FIGS.  11 - 13    a fifth design example of the backing plate with dimple-like projections and support elements, 
         FIG.  14    the embodiment according to  FIGS.  11 - 13    as a cross-sectional representation by the cross-section line according to  FIG.  11   , 
         FIG.  15    a sixth design example of the backing plate with dimple-like projections, but without support elements, 
         FIG.  16    the embodiment according to  FIG.  15    as a cross-sectional representation, and in 
         FIG.  17    the embodiment according to  FIGS.  15  and  16    as an enlarged section of the representation according to  FIG.  16   . 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a backing plate  1  produced according to the inventive method in a top view of the back side. The backing plate  1  has a front side  2 , onto which a friction pad can be applied, a back side  3 , a backing plate top side  17  and a backing plate bottom side  24 . A mounting device  4  for a spring element not shown in  FIG.  1    is shown on the back side  3  of the backing plate  1 . The mounting element  4  consists of a support element  9  for a spring base, two support elements  10  and  11  for respectively one spring leg, a common support element  18  for the spring legs, and a locking element  15  for the spring base. The locking element  15  also has an alignment slant  23  beyond which the spring base is pushed out when a spring element is inserted in order to come to rest between the locking element  15  and the support element  9 . 
     The spring element  5  can be formed as a wire spring, as is the case in the present design example. In the present wire spring  5 , the spring base  6  is a substantially semi-circular coil. This is followed by the spring legs  7 ,  8  extending approximately parallel to one another, in particular in the mounting device  4 . An approximately U-shaped section  35  of the spring element  5  and/or the wire spring is formed by the semicircular coil and the spring legs extending in parallel. The free and/or open ends  19 ,  20  of the legs  7  and  8  are at least regionally angled relative to one another, in particular the free ends  19 ,  20  extend outward in the assembled position. Support regions  21  and  22  are also provided at the free ends  19 ,  20 , by which the spring element  5  and/or the spring legs in their assembled state can—while in operation—support themselves against the brake system within the latter in order to enable the spring effect. The spring element  5  can approximately along its center have the transition from the U-shaped section  35  to the angled region of the legs  7 ,  8 . In particular, the inventive backing plate  1  can have such a spring element  5 , in particular a wire spring. 
     In this design example, the mounting device  4  is formed in a mirror-symmetrical fashion to a longitudinal center axis  16  of the backing plate  1 . Both the common support element  18  for the spring legs and the locking element  15  and the support element  9  for the spring base in this case lie on this longitudinal center axis  16  in a mirror-symmetrical fashion, while the support elements  10  and  11  of the respective spring legs are separated by the longitudinal center axis  16  in a mirror-symmetrical fashion. 
     A detailed illustration of the mounting device  4  in a perspective view from the backing plate top side  17  is shown in  FIG.  4   . It can be seen in this case that the support element  9  for the spring base is arranged on the back side  3  of the backing plate  1  in the region of the backing plate bottom side  24 . The locking element  15 , which is provided with an alignment slant  23  that points away from the support element  9 , is arranged adjacent to the support element  9  for the spring base. The spring base of a spring element to be inserted can be pushed over this alignment slant  23  such that the spring base can be securely positioned between the support element  9  of the spring base and the locking element  15 . The locking element  15  ensures that an inserted spring element cannot be easily removed from mounting device  4 . In addition, the support element  9  for a spring base can also still be provided with an undercut not incorporated here. 
     Furthermore, the illustration according to  FIG.  4    clearly shows the two support elements  10  and  11  on the back side  3  of the backing plate  1 . In the present design example, the support elements  10  and  11  each have an undercut  13 ,  14 , into which the spring legs of the spring element come to rest when the spring element is inserted. The undercuts  13  and  14  ensure that the spring element is captively held in the inserted state in the mounting device  4  in cooperation with the locking element  15  and the support element  9  for the spring base. Lastly,  FIG.  3    shows the common support element  18  (embodied in a cylindrical shape in the design example selected here) of the spring legs of the spring element. 
       FIG.  5    shows a further detailed illustration of the mounting device  4 , this time in a top view of the bottom side of the backing plate bottom side  24 . In this case, the front side  2  of the backing plate  1 , onto which a friction pad can be applied, can now also be seen. 
     The illustration according to  FIG.  5    clearly shows the undercuts  13  and  14  of the support elements  10  and  11  for the spring legs of a spring element. The support elements  10  and  11  are in this case formed such that they have a web  25 ,  26  that is substantially perpendicular to the back side  3  of the backing plate  1 , followed by a region  27 ,  28  extending substantially parallel to the back side  3  of the backing plate  1 . The undercuts  13  and  14  are formed such that their shapes are adapted to the profile or the cross-section of a spring leg of the spring element, which is round in cross-section. Such undercuts adapted to the shape of the spring legs result in a very good support effect of the support elements  10  and  11  as well as in a secure, captive arrangement of the spring element within the mounting device  4 . 
     The insertion of a spring element  5  into the mounting device  4  of the backing plate  1  is now shown in  FIGS.  2  and  3   . The spring element  5 , produced from a metal part or wire having a round cross-section, consists substantially of a rounded spring base  6 , which is followed by parallel regions of spring legs  7  and  8 . Support regions  21  and  22  are also arranged at the open ends  19 ,  20  of the legs  7  and  8 , by which the spring element  5  and/or the spring legs in their assembled state can—while in operation—support themselves against the brake system within the latter in order to enable the spring effect. 
     As can be seen from  FIG.  2   , the insertion of the spring element  5  begins by positioning the spring base  6  between the common support element  18  and the respective support elements  10  and  11  of the spring legs  7  and  8 , wherein the spring legs  7  and  8  are positioned opposite the common support element  18 . 
     Subsequently, the spring element  5  is now displaced in the direction of the support element  9  for the spring base  6 . The spring legs  7  and  8  are in this case positioned between their respective support elements  10  and  11 . The spring element  5  is captively positioned within the mounting device  4  by now pushing the spring element  5  with its spring base  6  over the alignment slant  23  of the locking element  15  until the spring base  6  rests between its support element  9  and the locking element  15 . While the spring base  6  is displaced on the alignment slants  23  of the locking element  15 , a stress is built up within the spring element  5 , which is again relieved when the spring base  6  is pushed over the alignment slant  23  and the locking element  15 . The spring base  6  in this case springs into the space between the locking element  15  and the support element  9  of the spring base  6 . The spring base  6  is therefore now securely and captively held in the mounting device  4  for the spring element  5  because the locking element  15  prevents the spring element  5  from retracting, while the undercuts  13  and  14  of the support elements  10  and  11  of the spring legs  7  and  8  make it impossible for the spring element  5  to pivot out of the mounting device  4 . 
     In operation within a brake system, the spring element  5  can now support itself with its spring legs  7  and  8  under load on the common support element  18 , wherein the backing plate  1  is thereby held in position. The spring element  5  is in this case adapted as a hold-down spring for the backing plate  1 . 
       FIGS.  6  to  8    show a second design example of a backing plate  1  according to the invention, which essentially corresponds to the first design example of  FIGS.  1  to  6   . However, in contrast to the first design example, a further support element  29  and  30  is provided for the spring legs  7  and  8 , respectively, which is arranged above the support and guide element  18  between the latter and the backing upper side  17 . However, in contrast to the support elements  10  and  11  of the spring legs  7  and  8 , the support elements  29  and  30  do not have undercuts. However, further exemplary embodiments are also conceivable, wherein the support elements  29  and  30  are also provided with undercuts. 
     In the design example of  FIGS.  6  to  8   , the support elements  29  or  30  with the respectively assigned support element  10  or  11 , respectively, of the spring legs  7  and  8  are designed substantially aligned in reference to the longitudinal center axis  16  and mirror-symmetrically to the longitudinal center axis  16 . Further exemplary embodiments can also provide that the support elements  29  and  30  have a larger or smaller distance with regard to the longitudinal center axis  16  than the support elements  10  and  11  and thus do not align with them, but still have mirror symmetry to the longitudinal center axis  16 . 
       FIG.  9    shows a third design example of an inventive backing plate  1  that substantially corresponds to the second design example of  FIGS.  6  to  8   . However, in contrast to the second design example, no support element  18  is provided for the spring legs  7 ,  8 . 
       FIG.  10    shows a fourth design example of the inventive backing plate  1  that substantially corresponds to the first design example according to  FIGS.  1  to  5   , although no support element  18  is provided for the spring legs  7 ,  8 . 
       FIGS.  11  to  14    show a fifth design example of the inventive backing plate  1 , wherein the backing plate  1 , substantially manufactured from steel, in the present example comprises a mounting device  4  with four dimple-like projections  31  adapted as support elements, which are also referred to as dimples. A different number of dimples  31  is of course also conceivable. The dimples  31  are provided on the back side  3  of the backing plate  1 . The spring legs  7 ,  8  are at least regionally abut the dimples  31 . As can be further seen from  FIGS.  11  to  13   , this exemplary embodiment also provides support elements  29  and  30  for the spring legs  7 ,  8 .  FIG.  14    shows a cross-sectional representation through the centerline according to  FIG.  11   . 
     The sixth design example according to  FIGS.  15  to  17    differs from the fifth design example in that the inventive backing plate  1  does not provide for lateral support elements  29  and  30  for the spring legs  7 ,  8 . The backing plate  1 , produced substantially from steel, has a plurality, in this case four, dimples  31  on which each spring leg  7 ,  8  rests at least regionally.  FIG.  16    is a cross-sectional view according to the cross-section line  36  through the dimples  31  in  FIG.  15   , and an enlarged cross-section of the view according to  FIG.  16    can be seen in  FIG.  17   . 
     As can be seen in particular from the enlarged illustration according to  FIG.  17   , the dimple-like projections  31  are formed as push-throughs and are therefore integral with the carrier plate  1 . 
     The dimple-like projections or dimples  31 , respectively, are produced by pressing through several circular dimples, for example with a diameter of approx. 6 mm, using a tool with a concave-shaped tip from the front side  2  of the carrier plate  1  such that a plurality of dimples  31  project from the carrier plate surface on the back side  3 . In general, the ratio of the dimple diameter to the carrier plate thickness can be between 1 and 2, preferably slightly above 1. 
     In a second method step, a tool is pressed in the opposite direction against the projecting dimples  31  in order to split the dimples  31  in a further forming process and to form projections  32  with undercuts  33  from the dimples  31 . A tool with a pyramidal tip can be used for this purpose, which facilitates the splitting of the dimples  31 . Conical tip tools may also be used, but those with a pyramidal tip are preferred. 
     As can be further seen from  FIG.  17   , the strong undercuts  33 , with which the friction pad can be anchored on the carrier plate  1  such that high shearing forces can be absorbed, are formed by splitting the projections  32 . Circular recesses  34  remain on the front side  2  of the carrier plate  1 , for example with a depth of 2 to 3 mm, the bottoms of which can have a convex curvature. 
     When pressing the friction pads onto the carrier plate  1 , the friction material of the friction pad can penetrate the undercuts  33  and firmly anchor itself there. 
     REFERENCE NUMERALS 
     
         
           1  Backing plate 
           2  Front side 
           3  Back side 
           4  Mounting device 
           5  Spring element 
           6  Spring base 
           7  Spring leg 
           8  Spring leg 
           9  Support element 
           10  Support element 
           11  Support element 
           13  Undercut 
           14  Undercut 
           15  Locking element 
           16  Longitudinal center axis 
           17  Backing plate top side 
           18  Support and guide element 
           19  End 
           20  End 
           21  Support region 
           22  Support region 
           23  Start-up slant 
           24  Backing plate bottom side 
           25  Web 
           26  Web 
           27  Region 
           28  Region 
           29  Support element 
           30  Support element 
           31  Dimple-like projections 
           32  Projections 
           33  Undercuts 
           34  Circular recesses 
           35  U-shaped section 
           36  Cross-section line