Abstract:
A vehicle brake assembly includes a multi-component lever assembly. The lever assembly includes a push rod receiving insert received into a push rod receiving insert opening. The multi-component lever assembly provides for alternate final configurations during the final assembly stages of the brake assembly. The operating shaft is assembled into the brake housing through a housing opening which is closed off by a closing plate. The push rod receiving insert received is then passed through a push rod opening and into the push rod receiving insert opening until locked in place.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a vehicle brake assembly and, more particularly, to a lever assembly for actuating the brake and a method of assembly therefor.  
           [0002]    Disc brake assemblies typically include a disc brake caliper that houses a piston for forcing a pair of friction elements or brake pads into engagement with a rotor. Heavy-duty vehicle brake assemblies commonly include multiple pistons that are actuated by a cam manipulated by a pneumatic actuator. The heavy-duty brake assemblies may be relatively complicated compared to passenger vehicle brake assemblies and may be specifically tailored to particular heavy vehicle applications.  
           [0003]    Various assembly line sequence limitations may require later assembly of certain brake mechanism components within the housing. One assembly line sequence limitation may be the desire to manufacture each brake assembly in an identical manner and assemble unique components for specific vehicle applications at final assembly stages to minimize tracking each brake assembly through the entire assembly process.  
           [0004]    One particular tracking issue arises as specific vehicle applications may provide an actuator push rod of a specific length that must be accommodated by the brake assembly. Various brake components specific to the push rod length are assembled into the brake assembly for the specific push rod. The brake assembly is then dedicated to a particular vehicle application due to the assembly of the components that correlate to a specific push rod length. Each brake assembly must then be tracked along the assembly line once the specific components are assembled to assure the appropriate brake assembly is assembled into the appropriate vehicle application.  
           [0005]    Disadvantageously, a relatively large number of individual brake components may already be assembled by the time the brake assembly reaches the final assembly stages.  
           [0006]    Assembly limitations stemming from the previously assembled components may then have to be addressed by utilizing different and perhaps small or less convenient housing openings to assemble the remaining components.  
           [0007]    Accordingly, it is desirable to provide a vehicle brake assembly which allows unique component installation during the final assembly stages while maintaining component reliability.  
         SUMMARY OF THE INVENTION  
         [0008]    The vehicle brake assembly according to the present invention provides a lever assembly that includes an operating shaft and a push rod receiving insert mounted thereto.  
           [0009]    The multi-component lever assembly provides for assembly during the final assembly stages of the brake assembly.  
           [0010]    A push rod receiving insert is received into a push rod receiving insert opening in an operating shaft. An insert groove is formed in a shank of the push rod receiving insert to receive a snap ring. The shank fits into the push rod receiving insert opening until the snap ring engages an operating shaft groove to lock the push rod receiving insert into the operating shaft.  
           [0011]    The operating shaft is assembled into the brake housing with the brake mechanism and the housing is assembled. The opening through which the operating shaft is assembled is closed by a closing plate. The push rod receiving insert is passed through a push rod opening and into the push rod receiving insert opening until locked in place.  
           [0012]    A alternative push rod receiving insert includes a shank and snap ring which are passed entirely through the push rod receiving insert opening until the snap ring exits the opposite end of the push rod receiving insert opening. The snap ring opens and the push rod receiving insert is secured in the operating shaft between the snap ring and a head of the push rod receiving insert.  
           [0013]    Another push rod receiving insert includes an interference retaining ring which fits between a shank of the push rod receiving insert and the push rod receiving insert opening inner diameter. The push rod receiving insert is secured in the operating shaft through an interference press fit.  
           [0014]    The present invention thereby provides a vehicle brake assembly which allows unique component installation during the final assembly stages while maintaining component reliability.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:  
         [0016]    [0016]FIG. 1 is a cross-sectional end view of a vehicle brake assembly of the present invention;  
         [0017]    [0017]FIG. 2 is a cross-sectional top elevation view of the present invention;  
         [0018]    [0018]FIG. 3 is an exploded perspective view of a lever assembly;  
         [0019]    [0019]FIG. 4A is an exploded view of the push rod receiving insert of the lever assembly illustrated in FIG. 3;  
         [0020]    [0020]FIG. 4B is an expanded view of the assembled push rod receiving insert illustrated in FIG. 4A;  
         [0021]    [0021]FIG. 4C is a perspective view of assembling the lever assembly into the brake housing;  
         [0022]    [0022]FIG. 5A is an exploded view of an alternate push rod receiving insert for the lever assembly illustrated in FIG. 3;  
         [0023]    [0023]FIG. 5B is an expanded view of the assembled push rod receiving insert illustrated in FIG. 5A;  
         [0024]    [0024]FIG. 6A is an exploded view of an alternate push rod receiving insert for the lever assembly illustrated in FIG. 3; and  
         [0025]    [0025]FIG. 6B is an expanded view of the assembled push rod receiving insert illustrated in FIG. 6A. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    [0026]FIG. 1 illustrates a general sectional view of a vehicle brake assembly  10 . The vehicle brake assembly  10  includes a housing  12  that may be constructed from one or more housing portions  12   a ,  12   b . A rotor  14  is arranged near or within the housing portion  12   b  to contain brake pads  16 , or friction elements, arranged on either side of the outer surfaces of the rotor  14 .  
         [0027]    An actuator  18 , typically an air chamber, actuates a brake mechanism  30  to force the brake pads  16  into engagement with the rotor  14 . The actuator  18  drives a push rod  20  through a push rod opening  21  to rotate a lever assembly  22  about an axis of rotation.  
         [0028]    The lever assembly  22  includes a cam  24  having a profile  25  that cooperates with the brake mechanism  30  to drive the brake pads  16 . The cam  24  is preferably received at least partially supported by a bearing block  26  supporting a plurality of needle bearings  28  within the housing portion  12   a . It should be understood that various actuating systems which are operated by a lever will benefit from the present invention.  
         [0029]    The opening  31  of the housing which receives the brake actuation mechanism  30  is closed off on the front side, that is, in the position facing the brake disk, by a closing plate  32  which may at least partially support the brake actuation mechanism  30 . The closing plate  32  is attached to the housing portion  12   a  by fasteners  34  or the like. Sealing elements are preferably located upon the sealing surfaces between the closing plate  32  and the housing  12 .  
         [0030]    In operation, upon actuation of the brake pedal by the vehicle operator, a signal is produced by a control module  33  to energize the actuator  18 . Heavy-duty vehicle brake assemblies typically include a pair of pistons  36  (FIG. 2) that transmit the force generated by the actuator  18  through the push rod  20 , lever assembly  22 , and the brake actuation mechanism  30  to the brake pads  16 . It is to be understood that any suitable number of pistons  36  may be used.  
         [0031]    Referring to FIG. 2, the brake pads  16  must be retracted after actuation to prevent the brake pads  16  from dragging on the rotor  14 . To this end, a return assembly  38  operates to retract the pistons  36 . The return assembly  38  includes a return plate  40  adjacent a plurality of teeth  42 . A return spring  44  is arranged between a portion of the housing  12  and the return plate  40 . The return spring  44  applies a force opposite the actuation force to the return plate  40  and into the pistons  36  to retract the brake pads  16 .  
         [0032]    Referring to FIG. 3, the lever assembly  22  includes an operating shaft  50  and a push rod receiving insert  52  mountable thereto. The operating shaft  50  includes the cam bearing surface  24  and defines the axis of rotation (FIG. 1). It should be understood that various operating shaft  50  profiles will benefit from the present invention.  
         [0033]    The push rod receiving insert  52  is preferably manufactured of a sintered metal (powder metallurgy) minimizing or alleviating the requirement or hardening of a segment  51  of the operating shaft  50 . It should be understood that although the push rod receiving insert  52  is disclosed as a substantially circular member in the illustrative embodiment, other shapes will also benefit from the present invention.  
         [0034]    The push rod receiving insert  52  includes a cupped segment  54  for receipt of the push rod  20  (FIG. 1). The push rod receiving insert  52  of a specific design, such as to accommodate a push rod  20  of a desired length specific to a particular brake assembly  10  may be selectively assembled to the common operating shaft  50  according to the present invention. That is, cupped segment  54  of the push rod receiving insert  52  may be of a predefined depth to accommodate a predetermined push rod  20  length. Likewise, operating shafts of a design specific to a particular brake assembly  10  may be interchangeably assembled with the push rod receiving insert  52  according to the present invention.  
         [0035]    Referring to FIG. 4A, push rod receiving insert  52  is received into a push rod receiving insert opening  56  in the operating shaft  50 . An insert groove  58  is formed in a shank  60  of the push rod receiving insert  52  to receive a snap ring  62 . The shank  60  fits into the push rod receiving insert opening  56  such that a head  64  of the push rod receiving insert  52  contacts the operating shaft  50  (FIG. 4B).  
         [0036]    An operating shaft groove  66  is formed in the inner diameter of the push rod receiving insert opening  56 . The snap ring  62  is preferably pre-assembled into the insert groove  58  prior to fitting the push rod receiving insert  52  into a push rod receiving insert opening  56 . The shank  60  is then pushed into the push rod receiving insert opening  56  until the snap ring  62  engages the operating shaft groove  66  to lock the push rod receiving insert  52  into the operating shaft  50  (FIG. 4B).  
         [0037]    As the push rod receiving insert  52  and the cupped segment  54  are preferably symmetric a rotational orientation feature need not be provided. That is, the cupped segment  54  will receive the push rod  20  irrespective of orientation, however, an orientation feature such as a slot and key can be alternatively or additionally readily incorporated.  
         [0038]    Referring to FIG. 4C, an assembly sequence for the lever assembly  22  is illustrated. The operating shaft  50  is assembled into the housing portion  12   b  and located upon the needle bearing  28  to cooperate with the brake actuation mechanism  30 . The brake actuation mechanism  30 , closing plate  32 , and housing portion  12   b  may then be assembled to housing portion  12   a . As opening  31  is now closed by closing plate  32 , the push rod receiving insert  52  is passed through the push rod opening  21  and into the push rod receiving insert opening  56  until locked in place.  
         [0039]    It should be understood that various assembly line sequence requirements may require later assembly of the push rod receiving insert  52  to the operating shaft  50  such as to accommodate a push rod  20  of a particular length. That is, when it is determined which vehicle the brake assembly  10  will be used in, the push rod receiving insert  52  appropriate to the push rod of that vehicle is selected and assembled to the operating shaft  50 . This is achieved through the push rod opening  21  even though the brake assembly  10  is substantially complete. The push rod opening  21  and single direction insertion and locking of the lever  52  according to the present invention provides the flexibility to accommodate such assembly line sequence requirements.  
         [0040]    Referring to FIG. 5A, another push rod receiving insert  52 ′ is received into the push rod receiving insert opening  56 ′ in the operating shaft  50  (FIG. 5B). The push rod receiving insert opening  56 ′ passes through the operating shaft  50 . An insert groove  64  is formed in a shank  66  of the push rod receiving insert  52 ′ to receive a snap ring  68 . The shank  66  fits through the push rod receiving insert opening  56  and a head  70  of the push rod receiving insert  52 ′ contacts the operating shaft  50  (FIG. 5B).  
         [0041]    As the push rod receiving insert  52 ′ is fitted into the push rod receiving insert opening  56 ′, the snap ring  68  is radially compressed into the groove  64 . The shank  66  and snap ring  68  are passed through the push rod receiving insert opening  56 ′ until the snap ring  66  exits the opposite end of the push rod receiving insert opening  56 ′. The snap ring  68  being no longer constrained by the push rod receiving insert opening  56 ′“snaps” open and the push rod receiving insert  52 ′ is secured in the operating shaft  50  between the snap ring  68  and the head  70  (FIG. 5B).  
         [0042]    Referring to FIG. 6A, another push rod receiving insert  52 ″ is received into the push rod receiving insert opening  56 ″ in the operating shaft  50  (FIG. 6B). An interference retaining ring  72  fits between a shank  74  of the push rod receiving insert  52 ″ and the push rod receiving insert opening  56 ″. The push rod receiving insert  52 ″ is thereby secured in the operating shaft  50  through an interference press fit. A relatively small amount of force may be utilized to install the push rod receiving insert  52 ″ as the push rod receiving insert  52 ″ will only receive unidirectional force from the push rod  20 . Again, the push rod receiving insert is inserted through the push rod opening  21  in both the FIGS. 5A and 6A embodiments.  
         [0043]    The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.