Abstract:
This invention relates to an improved brake shoe assembly and a disc brake assembly including such a brake shoe assembly. The disc brake assembly includes an anchor bracket adapted to be secured to a vehicle component; a brake caliper adapted to be secured to the anchor bracket; an inboard brake shoe and an outboard brake shoe carried by the disc brake assembly and adapted to be disposed on opposite axial sides of an associated brake rotor, each of the brake shoes including a pair of opposed ends; actuation means for selectively moving the shoes into frictional engagement with the rotor; and a first clip carried by at least one of the opposed ends of one of the brake shoes to thereby urge the one of the brake shoes against a trailing end of the anchor bracket to prevent caliper rotation when the disc brake assembly is actuated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to U.S. Ser. No. 10/811,076, filed Mar. 26, 2004, which is a continuation of PCT/US02/30539, filed Sep. 25, 2002, which claims the benefit of U.S. Provisional Application Ser. No. 60/324,705, filed Sep. 25, 2001. 
   BACKGROUND OF THE INVENTION 
   This invention relates in general to vehicle disc brake assemblies and in particular to an improved structure for a brake shoe assembly adapted for use in such a vehicle disc brake assembly. 
   Most vehicles are equipped with a brake system for retarding or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are typically actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefore are well known in the art. 
   A typical disc brake assembly includes an anchor bracket which is secured to a fixed, non-rotatable component of the vehicle. A pair of brake shoes are supported on the anchor bracket for sliding movement relative thereto. The brake shoes have respective friction pads which are disposed on opposite sides of a brake disc. The disc, in turn, is connected to the wheel of the vehicle for rotation therewith. To effect braking action, the brake shoes are moved inwardly toward one another so as to frictionally engage the opposed sides of the disc. Such frictional engagement causes retarding or stopping of the rotational movement of the disc and, therefore, the wheel of the vehicle in a controlled manner. 
   To accomplish this, the disc brake assembly further includes a caliper assembly for selectively moving the brake shoes into frictional engagement with the brake disc. The caliper assembly typically includes guide pins or other components to slidably support a caliper housing relative to the fixed anchor bracket. The caliper housing is generally C-shaped, having an inboard leg disposed adjacent the inboard brake shoe and an outboard leg disposed adjacent to the outboard brake shoe. One or more hydraulically or pneumatically actuated pistons are provided in respective cylindrical recesses formed in the caliper inboard leg adjacent to the inboard brake shoe. When the brake pedal is depressed, the piston and the inboard leg of the caliper are urged apart from one another. Specifically, the piston is urged outwardly, while the outboard leg of the caliper is urged inwardly. As mentioned above, the piston is disposed adjacent to the inboard brake shoe and, therefore, urges it outwardly toward the inner side of the disc. Because the caliper is slidably mounted on the pins of the anchor bracket, the caliper outboard leg (and, thus, the outboard brake shoe disposed adjacent thereto) are urged inwardly toward the outer side of the disc. As result, the brake shoes frictionally engage the opposed sides of the disc. 
   Prior art  FIGS. 1 and 2  illustrate a portion of a prior art vehicle disc brake assembly, indicated generally at  10 . The general structure and operation of the prior art disc brake assembly  10  is conventional in the art. Thus, only those portions of the prior art disc brake assembly  10  which are necessary for a full understanding of this invention will be explained and illustrated. 
   As shown in prior art  FIG. 1 , the disc brake assembly  10  is a sliding type of disc brake assembly and includes a generally C-shaped caliper, indicated generally at  12 . The caliper  12  includes an inboard leg portion  14  and an outboard leg portion  16  which are interconnected by an intermediate bridge portion  18 . The caliper  12  is slidably supported on a pair of pins  20  secured to an anchor bracket, indicated generally at  22 . The anchor bracket  22  is, in turn, secured to a stationary component of the vehicle. Such a stationary component can be, for example, an axle flange (not shown), when the disc brake assembly  10  is installed for use on the rear of the vehicle, or a steering knuckle (not shown), when the disc brake assembly  10  is installed for use on the front of the vehicle. 
   The pins  20  extend through non-threaded apertures  14 A formed in the inboard leg  14  of the caliper  12 . The pins  20  have respective threaded ends  20 A which are received in threaded apertures  22 A provided in anchor bracket  22 . The pins  20  support the caliper  12  for sliding movement relative to the anchor bracket  22  in both the outboard direction and the inboard direction. Such sliding movement of the caliper  12  occurs when the disc brake assembly  10  is actuated, as will be explained below. A pair of bolts (not shown) extend through a pair of non-threaded apertures  22 B formed in the anchor bracket  22  to secure the anchor bracket  22  to the stationary vehicle component. Alternatively, other known securing methods can be used to secure the anchor bracket  22  to the stationary vehicle component. 
   As best shown in prior art  FIG. 2 , the anchor bracket  22  includes a pair of axially and outwardly extending arms  24  and  26  which are interconnected at their inboard ends by an inner tie bar  28 . The arms  24  and  26  have upstanding guide rails  24 A and  26 A, respectively formed thereon. The guide rails  24 A and  26 A extend transverse to the arms  24  and  26 , respectively, and parallel to one another. The guide rails  24 A and  26 A slidably support an inboard brake shoe, indicated generally at  30 , and an outboard brake shoe, indicated generally at  32 , respectively. 
   The inboard brake shoe  30  includes a backing plate  34  and a friction pad  36 . The inboard backing plate  34  includes opposed ends having notches  34 A and  34 B formed therein, for supporting the inboard brake shoe  30  on the guide rails  24 A and  26 A of the anchor bracket  22 . The outboard brake shoe  32  includes a backing plate  38  and a friction pad  40 . The outboard backing plate  38  includes opposed ends having notches  38 A and  38 B formed therein, for supporting the outboard brake shoe  32  on the guide rails  24 A and  26 A of the anchor bracket  22 . Alternatively, the inboard brake shoe  30  can be supported on a brake piston of the prior art disc brake assembly  10 , while the outboard brake shoe  32  can be supported on the outboard leg portion  16  of the caliper  12 . 
   An actuation means (not shown) is provided for effecting the operation of the disc brake assembly  10 . The actuation means includes a brake piston (not shown) which is disposed in a counterbore or recess  14 B formed in the outboard surface of the inboard leg  14  of the caliper  12 . The actuation means can be hydraulic, electrical, pneumatic, and mechanical types. 
   The prior art disc brake assembly  10  further includes a brake rotor  42 , which is connected to a wheel (not shown) of the vehicle for rotation therewith. The illustrated brake rotor  42  includes a pair of opposed friction discs  44  and  46  which are spaced apart from one another by a plurality of intermediate fins or posts  48  in a known manner to produce a “vented” or “ventilated” brake rotor. The brake rotor  42  extends radially outwardly between the inboard friction pad  30  and the outboard friction pad  32 . 
   When it is desired to actuate the prior art disc brake assembly  10  to retard or stop the rotation of the brake rotor  42  and the vehicle wheel associated therewith, the driver of the vehicle depresses the brake pedal (not shown). In a hydraulically actuated system which is well known in the art, the depression of the brake pedal causes pressurized hydraulic fluid to urge the piston into engagement with the backing plate  34  of the inboard brake shoe  30 . As a result, the friction pad  36  of the inboard brake shoe  30  is moved into frictional engagement with the inboard friction disc  44  of the brake rotor  42 . At the same time, the caliper  12  slides on the pins  20  such that the outboard leg  16  thereof moves the friction pad  40  of the outboard brake shoe  32  into frictional engagement with the outboard friction disc  46  of the brake rotor  42 . As a result, the opposed friction discs  44  and  46  of the brake rotor  42  are frictionally engaged by the respective friction pads  36  and  40  to slow or stop relative rotational movement thereof. 
   SUMMARY OF THE INVENTION 
   This invention relates to an improved brake shoe assembly and a disc brake assembly including such a brake shoe assembly. The disc brake assembly includes an anchor bracket adapted to be secured to a vehicle component; a brake caliper adapted to be secured to the anchor bracket; an inboard brake shoe and an outboard brake shoe carried by the disc brake assembly and adapted to be disposed on opposite axial sides of an associated brake rotor, each of the brake shoes including a pair of opposed ends; actuation means for selectively moving the shoes into frictional engagement with the rotor; and a first clip carried by at least one of the opposed ends of one of the brake shoes to thereby urge the one of the brake shoes against a trailing end of the anchor bracket to prevent caliper rotation when the disc brake assembly is actuated. 
   Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a portion of a prior art vehicle disc brake assembly. 
       FIG. 2  is an exploded perspective view of selected components of the prior art vehicle disc brake assembly illustrated in  FIG. 2 . 
       FIG. 3  is a top view of a portion of a disc brake assembly including a first embodiment of a brake shoe assembly according to the present invention. 
       FIG. 4  is an outboard view of the disc brake assembly illustrated in  FIG. 3 . 
       FIG. 5  is a perspective view of a portion of the brake shoe assembly illustrated in  FIGS. 3 and 4  with the assembly having the first clip and the second clip installed thereon according to the present invention. 
       FIG. 6  is another perspective view of a portion of the brake shoe assembly illustrated in  FIGS. 3 and 4  with the assembly having the first clip and the second clip installed thereon. 
       FIG. 7  is a view of the first clip illustrated in  FIGS. 3–6 . 
       FIG. 8  is another view of the first clip. 
       FIG. 9  is a view of the second clip illustrated in  FIGS. 3–6 . 
       FIG. 10  is another view of the second clip. 
       FIG. 11  is an exploded perspective view of a portion of the brake shoe assembly illustrated in  FIGS. 3–6  with the assembly having the first clip installed thereon. 
       FIG. 12  is another exploded perspective view of a portion of the brake shoe assembly illustrated in  FIGS. 3–6  with the assembly having the first clip and the second clip installed thereon. 
       FIG. 13  is a view similar to  FIG. 5  showing a portion of a second embodiment of a brake shoe assembly according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, there is illustrated in  FIGS. 3 and 4  a portion of a disc brake assembly, indicated generally at  50 , including a first embodiment of an outboard brake shoe assembly, indicated generally at  70 , according to the present invention. The general structure and operation of the disc brake assembly  50  is conventional in the art and is generally similar to that described above in connection with prior art  FIGS. 1 and 2 . Thus, only those portions of the disc brake assembly  50  which are necessary for a full understanding of this invention will be explained and illustrated. Although this invention will be described and illustrated in connection with the particular kind of vehicle disc brake assembly  50  disclosed herein, it will be appreciated that this invention may be used in connection with other kinds of disc brake assemblies if so desired. For example, the invention can be used in conjunction with other single piston, twin piston, single opposed piston and twin opposed piston disc brake assemblies. 
   Briefly, as shown in  FIGS. 3 and 4 , the disc brake assembly  50  includes a twin piston caliper  52  and an anchor bracket or abutment  54 . Pins  56  extend through apertures (not shown) formed in the caliper  52  and have ends which are received in apertures provided in anchor bracket  54  to support the caliper  52  for sliding movement relative to the anchor bracket  54 . 
   In the illustrated embodiment, the anchor bracket  54  includes an inner tie bar  58 , an outer tie bar  60 , and a pair of arms  62  extending therebetween. The arms  62  have guide rails  64  formed thereon. Each of the guide rails  64  is provided with notch or recess (not shown) formed therein to support the outboard brake shoe assembly  70  and an inboard brake shoe assembly  66 . Alternatively, the structure of the disc brake assembly  50 , including the structure of the caliper  52  and/or the anchor bracket  54 , can be other than illustrated and described if so desired. 
   Turning now to  FIGS. 5 and 6 , the first embodiment of the brake shoe assembly  70  will be discussed. As shown therein, the brake shoe assembly  70  includes a brake shoe  72 , a first or inner bias spring clip  74  and a second or outer retractor spring clip  76 . As best shown in  FIGS. 11 and 12 , the brake shoe  72  is generally flat and arcuate and includes a backing plate  78  and a friction pad  80  secured thereto. The backing plate  78  is formed from a suitable material by a suitable process, such as for example, from steel by a stamping process. The friction pad  80  is typically secured to the backing plate  78  by a suitable process, such as bonding and/or riveting. 
   The backing plate  78  includes opposed ends (only one of such ends being illustrated) having a tab or protrusion  82  formed thereon. Preferably, the tab  82  on each of the ends of the backing plate  78  is identical to one another. The tab  82  includes a top or first edge  82 A, a lower or second edge  82 B and a side or third edge  82 C. The top edge  82 A and the lower edge  82 B are generally parallel to one another and generally perpendicular to the side edge  82 C. The tabs  82  are adapted to be received in the notches provided in the guide rails  64  of the anchor bracket  54  to slidably support the pair of brake shoe  72  (and also the brake shoe  66 ), for sliding movement between a non-braking position, wherein the brake shoes  72  and  66  are spaced from contact from a brake rotor (not shown), and a braking position, wherein the brake shoes  72  and  66  frictionally engage the opposed brake surfaces of the brake rotor. The backing plate  78  further includes a projection  86  provided thereon. Preferably, the projection  86  is integral with the backing plate  78  and is formed by a semi-pierce operation; however, the projection  86  can be formed other than illustrated and described if so desired. Alternatively, the tabs  82  do not have to be identical to one another and/or the structure or configuration of one or both of the tabs  82  can be other than illustrated if so desired. 
   Referring now to  FIGS. 7 and 8 , the structure of the first clip  74  will be discussed. As shown therein, the first clip  74  includes first or lower portion  90 , a second or upper portion  92 , and a third or intermediate portion  94  which connects the first portion  90  and the second portion  92  together. The first portion  90  is generally flat and is provided with an opening  96  formed therethrough. The opening  96  is adapted to receive an associated projection  86  (shown in  FIGS. 5 ,  11  and  12 ), provided on the backing plate  78  of the brake shoe  72  to assist in positioning and securing the first clip  74  on the brake shoe  72 . 
   The second portion  92  is generally V-shaped and includes a first leg or extension  100 , a second leg or extension  102 , and a third leg  104  which connects the first leg  100  and the second leg  102  together. The first leg  100  is generally flat and is located generally perpendicular with respect to the first portion  90 . The second leg  102  is located at a predetermined angle with respect to the first leg  100  and includes an inwardly turned or curled remote end  106 . 
   Preferably, as shown in the illustrated embodiment, the first clip  74  is installed only on the leading end of the outboard brake shoe  72  of the disc brake assembly  50 . Alternatively, the first clip  74  could be installed on the trailing end of both of the brake shoes  72  and  66  of the disc brake assembly  50  if so desired. In operation, as best shown in  FIG. 4 , the legs  100 ,  102  and  104  of the upper portion  92  and  106  are operative to push or urge the trailing end of the brake shoe  72  against the anchor bracket  54  to keep the caliper  52  from rotating during application of the disc brake assembly. The first clip  74  is formed from a suitable material by a suitable process, such as for example from stainless steel or carbon steel by a stamping process. The first clip  74  can be coated with a protective corrosion resisting material, such as for example geomet L, polytetrafluoroethylene (PTFE) or E-coated, if so desired. Alternatively, the structure or shape of one or more of the portions  90 ,  92  and  94  of the first clip  74  can be other than illustrated if so desired. 
   Referring now to  FIGS. 9 and 10 , there structure of the second clip  76  will be discussed. As shown therein, the second clip  76  includes a first portion  110 , which is adapted to be positioned adjacent the surface  12 C of the anchor bracket  12  so as to react thereagainst, and a second portion  112 , which is adapted to be operatively connected to an associated tab  82  and  84  of the backing plate  78  of the brake shoe  72  to thereby secure the first clip  74  onto the brake shoe  72 . In the illustrated embodiment, the first portion  110  of the second clip  76  is generally U shaped and includes a protruding tab  116  extending from a main or center body portion  118 . The tab  116  has a remote end  120  which is inwardly turned or curled. 
   The second clip  76  further includes a plurality of arms, in this embodiment, the spring  76  includes four arms  122 ,  124 ,  126 , and  128 . The arm  128  is further provided with a pair of arms  130  and  132  extending from opposed sides thereof. The arm  130  includes a generally flat side wall  132  and a partly wavy or curled remote end  134 . Similarly, the arm  132  includes a generally flat side wall  136  and a partly wavy remote end  138 . In this embodiment, the arms  130  and  132  are symmetrical and provide a symmetrical shoe attachment feature. 
   Preferably, as shown in the illustrated embodiment, the second clip  76  is installed on both ends of only the outboard brake shoe  72  of the disc brake assembly  50 . Alternatively, the second clip  76  could be installed only on the trailing end of the outboard brake  70  having the first clip  74  installed thereon if so desired. In operation, as best shown in  FIG. 4 , the tab  116  of the first portion  110  and the arms  122 ,  124  and  126  are operative to apply a retraction force to move or urge the brake shoes  72  from engagement with the rotor when the brakes are released. The second clip  76  is formed from a suitable material by a suitable process, such as for example from carbon steel by a stamping process. The second clip  76  can be coated with a protective corrosion resisting material, such as for example geomet L, PTFE or E-coated, if so desired. Alternatively, the structure or shape of one or both of the portions  110  and  112  of  94  of the second clip  76  can be other than illustrated if so desired. 
   The arm  126  is adapted to be disposed against portion of the first portion  90  of the first clip  74  to assist in securing the first clip  74  onto the backing plate  78  of the brake shoe  72 . Also, the arms  130  and  132  are adapted to be disposed over the tab  82  of the backing plate  78  and, in combination with the arms  126  and  128 , cooperate to assist in securing the second clip  76  along with the first clip  74  onto the backing plate  78  of the brake shoe  72 . 
   Referring now to  FIG. 13  and using like reference numbers to indicate corresponding parts, there is illustrated a portion of a second embodiment of a brake shoe assembly, indicated generally at  170 , according to the present invention. In this embodiment, the clip  74  is provided with a projection  186  formed thereon which is adapted to be disposed in an opening  196  (the opening shown in phantom in  FIG. 13 ), provided in the backing plate  78  of the brake shoe  72 . 
   One advantage of the present invention is that the spring clips  74  and  76  can be attached to the brake shoe without staking. As a result, less labor is required for assembly, a simplified location is presented and packaging advantages may be possible. 
   In accordance with the provisions of the patent statues, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that the invention may be practiced otherwise than as specifically explained and illustrated without departing from the scope or spirit of the attached claims.