Abstract:
This invention relates to a drum-in-hat disc brake assembly. According to one embodiment of the invention, only four fasteners extend through the associated apertures of the backing plate, the drum-in-hat adapter, the axle flange and the caliper bracket for securing the caliper bracket, drum-in-hat adapter and the backing plate to the axle flange. Two of the four fasteners extend through the two apertures of the caliper bracket and at least partially into two of the four apertures of the axle flange to thereby secure the caliper bracket to the axle flange. The other two of the four fasteners extend through the two smaller apertures of the backing plate and the drum-in-hat adapter and at least partially into the remaining two apertures of the axle flange to thereby secure the backing plate and the drum-in-hat adapter to the axle flange.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to vehicle brake assemblies and in particular to an improved structure for mounting a vehicle drum-in-hat type of disc brake assembly to the vehicle. 
     Most vehicles are equipped with a brake system for slowing 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. In some instances, the disc brake assembly can be a “drum-in-hat” type of disc brake assembly. The brake assemblies are 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 therefor, are well known in the art. 
     A typical drum-in-hat type of disc brake assembly includes a hydraulically or pneumatically actuated disc service brake and a mechanically actuated drum-in-hat parking and emergency brake. The disc service brake includes a rotor which is secured to the wheel of the vehicle for rotation therewith. The rotor includes a pair of opposed friction plates which are selectively engaged by portions of a caliper assembly. The interior of the rotor defines an cylindrical braking surface. 
     A caliper assembly is slidably supported by pins secured to a mounting flange. The mounting flange is secured to a non-rotatable component of the vehicle, such as the steering knuckle or the axle flange. To accomplish this, typically two threaded bolts extend through the mounting flange and are received in threaded apertures provided in the non-rotatable vehicle component to thereby secure the mounting flange to the non-rotatable vehicle component. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the rotor. The brake shoes are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from the opposed friction plates of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed friction plates of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the friction plates of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle. 
     The drum-in-hat parking and emergency brake includes a pair of opposed arcuate brake shoes which are supported on a backing plate for selective movement relative thereto. The backing plate is secured to the mounting flange, or alternatively, can be formed integral therewith. To accomplish this in the case of the former type of structure, typically four threaded bolts extend through the backing plate and through openings provided in the mounting flange and nuts installed thereon to secure the backing plate to the mounting flange. Each of the brake shoes has a friction pad or lining secured thereto. The brake shoes extend within the cylindrical braking surface of the rotor. To effect parking and emergency braking action, the operator of the vehicle manually pulls an actuating lever. The lever is connected to an actuation cable having a park brake cable end which, when pulled, actuates a mechanical actuating mechanism. The actuating mechanism is located adjacent one of the ends of the brake shoes and is operative to move the brake shoes outwardly apart from one another such that the friction pads frictionally engage the cylindrical braking surface of the rotor. Such frictional engagement causes slowing or stopping of the rotational movement of the rotor and, therefore, the wheel of the vehicle in a controlled manner. 
     SUMMARY OF THE INVENTION 
     This invention relates to an improved structure for mounting a vehicle drum-in-hat type of disc brake assembly to the vehicle. The drum-in-hat disc brake assembly includes a backing plate adapted to support a drum brake shoe assembly of the drum-in-hat parking and emergency brake, a drum-in-hat adapter, an axle flange, and a caliper bracket adapted support a disc brake caliper assembly of the disc service brake. According to one embodiment of the invention, the backing plate has a centrally located aperture and at least two smaller mounting apertures formed therein about the centrally located aperture thereof. The drum-in-hat adapter has a centrally located aperture and at least two smaller mounting apertures formed therein about the centrally located aperture thereof. The axle flange has a centrally located aperture and at least four mounting apertures formed therein about the centrally located aperture. And the caliper bracket has at least two apertures formed therein. In this embodiment, only four fasteners extend through the associated apertures of the backing plate, the drum-in-hat adapter, the axle flange and the caliper bracket for securing the caliper bracket, drum-in-hat adapter and the backing plate to the axle flange. Two of the four fasteners extend through the two apertures of the caliper bracket and at least partially into two of the four apertures of the axle flange to thereby secure the caliper bracket to the axle flange. The other two of the four fasteners extend through the two smaller apertures of the backing plate and the drum-in-hat adapter and at least partially into the remaining two apertures of the axle flange to thereby secure the backing plate and the drum-in-hat adapter to the axle flange. 
     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 an exploded perspective view of a first embodiment of a drum-in-hat disc brake assembly in accordance with the present invention. 
     FIG. 2 is a another exploded perspective view of the drum-in-hat disc brake assembly illustrated in FIG. 1 in accordance with the present invention. 
     FIG. 3 is an exploded perspective view of a selected portion of the drum-in-hat disc brake assembly illustrated in FIGS. 1 and 2 in accordance with the present invention. 
     FIG. 4 is an outboard view of the assembled components of the drum-in-hat disc brake assembly illustrated in FIGS. 1-3 in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, there is illustrated in FIGS. 1 and 2 a portion of a drum-in-hat type of disc brake assembly, indicated generally at  10 , in accordance with the present invention. The drum-in-hat disc brake assembly  10  includes a hydraulically or pneumatically actuated disc service brake (not shown), and a drum-in-hat parking and emergency brake. The general structure and operation of the drum-in-hat disc brake assembly  10  is conventional in the art. Thus, only those portions of the drum-in-hat disc brake assembly  10  which are necessary for a full understanding of this invention will be explained and illustrated in detail. Although this invention will be described and illustrated in conjunction with the particular vehicle drum-in-hat disc brake assembly  10  disclosed herein, it will be appreciated that this invention may be used in conjunction with other drum-in-hat disc brake assemblies. 
     The illustrated drum-in-hat disc brake assembly  10  includes a backing plate  12 , a drum-in-hat adapter  14 , an axle flange  16  and a caliper bracket  18 . The backing plate  12  is preferably a stamped metal backing plate and includes a relatively large central opening  22  and a plurality of smaller holes  24 A- 24 D formed therein about the central opening  22 . In the illustrated embodiment, the backing plate  12  is provided with four such smaller holes  24 A- 24 D. As will be discussed below, the central opening  22  permits an outer end of a rotatable axle (not shown) to extend therethrough to a wheel (not shown) of the vehicle. Alternatively, the structure of the backing plate  12  can be other than illustrated if so desired. For example, the two apertures  24 A and  24 B could be replaced with a single aperture, shown in phantom in FIG. 4 by reference character  24 F, preferably located generally intermediate the two disclosed apertures  24 A and  24 B. 
     In the illustrated embodiment, the backing plate  12  also includes a generally elongated, slotted first opening  26 , a generally elongated, slotted opening  28 , and two smaller openings  30 A and  30 B formed therein. The first slotted opening  26  is adapted to allow an abutment member  32  of the drum-in-hat adapter  14  to extend therethrough. The second opening  28  is adapted to allow an actuator  34  of the parking and emergency brake to extend therethrough. Pins  38 A and  38 B of conventional pivot pin and spring-clip assemblies extend through the openings  28 A and  28 B, respectively, of the backing plate  12  and through associated openings  54 A and  56 A provided in a pair of brake shoes  54  and  56 , respectively. The pins  38 A and  38 B have outer ends which are adapted to be fastened or secured to clips  58  and  60  assemblies to secure the brake shoes  54  and  56  to the backing plate  12  in a conventional manner. The illustrated drum-in-hat brake assembly  10  also includes a pair of retraction springs  120  and  122  and a pad wear adjuster mechanism  124 , all of which are conventional in the art. Alternatively, the construction of the drum-in-hat brake assembly  10  can be other than illustrated if so desired. Alternatively, the construction of the drum-in-hat brake assembly  10  can be other than illustrated if so desired. 
     The drum-in-hat adapter  14  is preferably formed from cast iron and includes a relatively large central opening  62  and a plurality of smaller holes  64 A- 64 E formed therein about the central opening  62 . In the illustrated embodiment, the adapter  14  is provided with five such smaller holes  64 A- 64 E. The holes  64 A- 64 D of the adapter  14  are formed to be in alignment with the holes  24 A- 24 D, respectively, of the backing plate  12  for a purpose to be discussed below. As will be discussed below, in the illustrated embodiment the apertures  64 C and  64 D of the drum-in-hat adapter  14  are preferably threaded apertures. 
     In the illustrated embodiment, the adapter  14  also includes a generally elongated, slotted opening  66 , and a cable attaching flange  68 . The elongated slotting opening  66  is adapted to allow a lever of the actuator  34  to pass therethrough. The cable attaching flange  68  is adapted to support a cable portion (not shown) of the parking and emergency brake cable assembly. Alternatively, the structure of the drum-in-hat adapter  14  can be other than illustrated if so desired. For example, depending upon the structure of the backing plate  12 , the two apertures  64 A and  64 B could be replaced with a single aperture, such as shown in phantom in FIG. 3 by reference character  64 F, preferably located generally intermediate therebetween. 
     The axle flange  16  is preferably a metal forging or stamping and includes a relatively large central opening  72  and a plurality of smaller holes  74 A- 74 E formed therein about the central opening  72 . In the illustrated embodiment, the axle flange  16  is provided with five such smaller holes  74 A- 74 E. The holes  74 A- 74 E of the axle flange  16  are formed to be in alignment with the holes  64 A- 64 E, respectively, of the adapter  14  for a purpose to be discussed below. Also, in the illustrated embodiment, the two apertures  74 C and  74 D are preferably non-threaded or through apertures for a purpose to be discussed below. Alternatively, the structure of the axle flange  16  can be other than illustrated if so desired. For example, depending upon the structure of the drum-in-hat adapter  14  and the backing plate  12 , the two apertures  74 C and  74 D could be replaced with a single threaded or non-threaded aperture (not shown) located generally intermediate therebetween. In this case, it may be necessary to provide some other type of structure/means to restrain or prevent the rotation of the attached caliper bracket  18 . For example, a suitable structure/means to accomplish this could be a small type of fastener, such as a self-tapping screw, or could be a non-fastener device, such as an extension or protuberance provided on one component which is adapted to be received into a recess provided on another component. Also, the two apertures  74 A and  74 B could be replaced with a single aperture, such as shown in phantom in FIG. 3 by reference character  74 F, preferably located generally intermediate therebetween. In the illustrated embodiment, the holes  64 E of the drum-in-hat adapter  14  and  74 E of the axle flange  16  are adapted to receive a speed sensor (not shown) of a vehicle anti-lock brake system. Alternatively, the apertures  64 E and  74 E could be eliminated if a speed sensor is not part of the brake assembly. 
     As best shown in FIG. 2, the caliper bracket  18  includes a pair of axially and outwardly extending arms  80  and  82  which are interconnected at their inboard ends by an inner tie bar  84  and at their outboard ends by an outer tie bar  86 . The arms  80  and  82  have respective apertures  80 A and  82 A formed therein, and respective upstanding guide rails  80 B and  82 B formed thereon. The guide rails  80 B and  82 B extend transverse to the arms  80  and  82 , respectively, and parallel to one another. The guide rails  80 B and  82 B slidably a pair of brake shoes  150  and  152  thereon, as shown in FIG.  4 . The apertures  80 A and  82 A are adapted to receive suitable fasteners to slidably or fixedly secure a disc brake caliper  124 , shown in FIG. 4, of the disc service brake to the caliper bracket  22 . 
     The caliper bracket  22  further includes a pair of mounting legs or extensions  90  and  92 . In the illustrated embodiment, the legs  90  and  92  extend from the inner tie bar  84 . The mounting leg  90  includes an aperture  90 A formed therethrough, and the mounting leg  92  includes an aperture  92 A formed therethrough. In the illustrated embodiment, the apertures  90 A and  92 A are non-threaded apertures. Alternatively, the structure of the caliper bracket  22  including the apertures  90 A and  92 A can be other than illustrated if so desired. 
     In the illustrated embodiment, the components of the drum-in-hat brake assembly  10  are secured to the axle flange  16  in the following manner. A pair of threaded bolts  100  and  102  and nuts  104  and  106  are used to secure the backing plate  12  and the drum-in-hat adapter  14  to the axle flange  16 . The bolt  100  includes an enlarged head  100 A, a main body  100 B having a serrated portion adjacent the head  100 A, and a threaded end  100 C. The bolt  100  extends through the aperture  24 A of the backing plate  12 , the aperture  64 A of the drum-in-hat adapter  14 , and the aperture  74 A of the axle flange  16 . The nut  104  is then installed on the threaded end  100 C of the bolt  100 . Alternatively, the structure of the bolt  100  can be other than illustrated and described if so desired. For example, the serrations on the main body  100 B of the bolt  100  could be eliminated. 
     Similarly, the bolt  102  includes an enlarged head  1002 A, a main body  102 B having a serrated portion adjacent the head  102 A, and a threaded end  102 C. The bolt  102  extends through the aperture  24 B of the backing plate  12 , the aperture  64 B of the drum-in-hat adapter  14 , and the aperture  74   b  of the axle flange  16 . The nut  106  is then installed on the threaded end  102 C of the bolt  102 . Alternatively, the backing plate  12  and the drum-in-hat adapter  14  can be secured to the axle flange  16  by other methods if so desired. For example, the nuts  104  and  106  could be eliminated and the apertures  74 A and  74 B in the axle flange  16  could be threaded to receive the respective threaded ends  100 C and  102 C of the bolts  100  and  102 . Also, instead of using the two bolts  100  and  102 , only a single bolt (not shown) could be used to secure the backing plate  12  and the drum-in-hat adapter  14  to the axle flange  16  in the ways discussed above. In addition, depending upon the particular vehicle design, one or more smaller self-tapping type screws (not shown) could be used to secure the backing plate  12  to the drum-in-hat adapter  14 , preferably in the region near the holes  24 C and  24 D of the backing plate  12 . 
     In the illustrated embodiment, a pair of threaded bolts  110  and  112  are provided to secure the caliper bracket  18  to the axle flange  16  and the drum-in-hat adapter  14 . The bolt  110  includes a hex-shaped head  100 A and a threaded body  100 B. The bolt  110  extends through the aperture  90 A of the caliper bracket  18 , through the aperture  74 C of the axle flange  16  and threadably received in the threaded aperture  64 C of the drum-in-hat adapter  14 . 
     Similarly, the bolt  112  includes a hex-shaped head  112 A and a threaded body  112 B. The bolt  112  extends through the aperture  92 A of the caliper bracket, through the aperture  74 D of the axle flange  16  and is threadably received in the aperture  64 D of the drum-in-hat adapter  14 . Alternatively, the structure of the bolt  110  and  112  can be other than illustrated and described if so desired. For example, the bolts  110  and  112  could be an internal drive type fastener, such as a TORX® fastener. 
     Also, the caliper bracket  18  can be secured to the drum-in-hat adapter  14  by other methods if so desired. For example, the apertures  64 C and  64 D of the drum-in-hat adapter  14  could be through holes and the bolts  110  and  112  could extend through the holes  90 A and  92 A of the caliper bracket  18 , through the holes  74 C and  74 D of the axle flange, and through the holes  64 C and  64 D of the adapter  14  and nuts installed thereon. These nuts could be supplied loose or could be welded or otherwise attached to the outboard side of the drum-in-hat adapter  14 . 
     In addition, the caliper bracket  18  can be secured to the axle flange  16  or to the axle flange, the drum-in-hat adapter  14  and the backing plate  12  by other methods if so desired. For example, to secure the caliper bracket  18  to the axle flange  16 , the apertures  74 C and  74 D of the axle flange  16  could be threaded  5  apertures. In this case, the bolts  110  and  112  extend through the apertures  90 A and  92 A of the caliper bracket  18  and are threadably received in the respective threaded apertures  74 C and  74 D of the axle flange  16  to secure the caliper bracket  18  to the axle flange  16 . To secure the caliper bracket  18  to the axle flange  16 , the drum-in-hat adapter  14  and the backing plate  12 , the apertures  74 C and  74 D of the axle flange  16  could be through holes and the apertures  64 C and  64 D of the drum-in-hat adapter  14  could also be through holes to enable the threaded ends  110 B and  112 B of the bolts  110  and  112 , respectively, to extend therethrough and nuts (not shown) installed thereon to secure the caliper bracket  18  to the axle flange  16 , the drum-in-hat adapter  14  and the backing plate  12 . Also, instead of using two bolts  110  and  112 , only a single bolt (not shown) could be used to secure the caliper bracket  18  to the axle flange  16  or to the axle flange  16  and other selected components of the drum-in-hat disc brake assembly  10  in the ways discussed above if so desired. 
     Although the present invention has been illustrated and described in conjunction with the particular drum-in-hat disc brake assembly disclosed herein, it will be appreciated that this invention can be used in conjunction with other drum and disc brake assemblies. 
     In accordance with the provisions of the patent statutes, 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.