Abstract:
A torque-limiting a clutch brake is provided for an input shaft of a vehicle transmission. The clutch brake employs wave springs in its torque-limiting feature and can largely be fabricated from sheet metal parts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/821,784, filed May 10, 2013. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to clutch brakes for transmissions. 
       BACKGROUND OF THE INVENTION 
       [0003]    Clutch brakes are use to stop rotation of a transmission input shaft in constant mesh transmissions. The clutch brake in an annular member that is torsionally connected on an input shaft of a transmission via a grooved connection. The clutch brake is also axially slidable on the transmission input due to the grooved connection. Most clutch brakes are placed on the transmission input shaft between a release assembly that includes a release bearing and housing and front part of a transmission frame inside of a transmission bell housing. When a transmission gear shift is mandated, a shift fork will pull back the release bearing housing forcing the frame of the release bearing housing against a front frictional lining of the clutch brake. The back of the clutch break has a frictional lining that engages with the frame of the transmission adjacent the transmission input shaft. Pulling back on the release housings bearing disconnects the clutch assembly which connects the transmission to the engine and additionally causes the clutch brake (which is torsionally connected to the transmission input shaft) to cause the transmission input shaft to stop rotating. Clutch brakes typically wear out faster than clutches and have to be replaced. Removal is difficult since access to the clutch brake is only through an inspection port of the transmission bell housing unless one pulls out the transmission from the vehicle&#39;s engine. Typically the clutch brake is torn off the transmission input shaft. It is desirable to provide a clutch brake that can be removed from a transmission shaft without the required tear off. It is also desirable to provide such a clutch brake that has a torque limiter function. It is also desirable to provide a clutch brake that has a hinged connection, has a torque limiter, can be mainly fabricated from stamped sheet metal parts and that can have as few as parts as possible. 
       SUMMARY OF THE INVENTION 
       [0004]    To fulfill the above noted and other manifold desires, a revelation of the present invention is brought forth. In a preferred embodiment, the present invention brings forth a torque-limited two part hinged clutch brake for a transmission input shaft. The clutch brake has first and second arcuate shells which are hinged together. Encased within the arcuate shells are first and second inner collars which have a tab for interconnection with an axial groove in the transmission input shaft. Circumferentially interconnected with the inner collars and positioned radially outward of the inner collars are outer collars. Wave springs are provided which have a position fixed with respect to the arcuate shells for urging the outer collars against an opposite interior wall of the arcuate shells. A weld nut is provided connected to one of the shells which is overlapped by an eyelet formed on the opposite shell to allow for permanent installation of the clutch brake by insertion of a threaded fastener. 
         [0005]    Other advantages of the present invention will become more fully apparent from a review of the invention as it is provided in the detailed description. 
         [0006]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0008]      FIG. 1  is a perspective view of a clutch brake according to the present invention; 
           [0009]      FIG. 2  is an enlarged perspective view of a hinged portion of the clutch brake shown in  FIG. 1 ; 
           [0010]      FIG. 3  is a perspective view of the clutch brake shown in  FIG. 1  with the first rear backer plate being removed for clarify of illustration; 
           [0011]      FIG. 4  is a perspective view of the clutch brake shown in  FIG. 3  with both of the rear backer plates being removed for clarity of illustration; 
           [0012]      FIG. 5  is a perspective view illustrating a detent function of a weld nut which holds first and second arcuate shells of the clutch brake together; 
           [0013]      FIG. 6  is a view similar to that of  FIG. 5  illustrating the opposite end of the weld nut than that shown in  FIG. 5 ; 
           [0014]      FIG. 7  is an exploded view of the major components of the clutch brake shown in  FIG. 1 ; 
           [0015]      FIG. 8  is an enlarged perspective view illustrating the connection of the weld nut tongue being fitted within a slot of the second rear backer plate of the clutch brake of the present invention; 
           [0016]      FIG. 9  is a view similar to that of  FIG. 9  illustrating the weld not from the opposite view point showing the mound region of the weld nut with the first and second front backer plates being removed for clarity of illustration; 
           [0017]      FIG. 10  is a view similar to that of  FIG. 5  illustrating the detent function of the weld nut; 
           [0018]      FIG. 11  is a sectional view along an outer flange area of the clutch brake of the present invention; 
           [0019]      FIG. 12  is a sectional view of the clutch brake of the present invention taken through the weld nut of the present invention; 
           [0020]      FIG. 13  is a sectional view taken along the hinge portion of the present invention; 
           [0021]      FIG. 14  is a plan view of the wave spring of the present invention; 
           [0022]      FIG. 15  is a side elevational view of the wave spring shown in  FIG. 15 ; and 
           [0023]      FIGS. 16 through 20  are sectional views similar to that of  FIG. 14  of alternate preferred embodiment hinge portions of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0025]    Referring to  FIGS. 1 through 14 , a clutch brake  7  according to the present invention is provided. Clutch brake  7  has a rear backer plate  10 . As used in this application the direction rear means towards the transmission, the designation front means towards the engine end of a transmission input shaft. The first rear backer plate  10  is typically fabricated from a stamped sheet metal. Typical materials for the first rear backer plate will be that of a low carbon steel. Bonded to the first rear backer plate  10  or otherwise connected is a friction lining  12 . 
         [0026]    Weldably connected to the first rear backer plate  10  is a first front backer plate  14 . The material of the first front backer plate is typically similar or identical to the material of the first rear backer plate  10 . The first front backer plate  14  has a flat radial flange portion  16 . The flat radial flange portion  16  of the first backer plate is connected with an axially extending portion  18 . The first front backer place axially extending portion  18  is connected with a generally radial friction lining support portion  20 . The rear backer plate has a radially extending flat flange portion  22  which is adjacent to the flange portion  16  of the first backer plate. The rear backer plate has a lining support portion  24  for supporting the lining  12 . The linings for the front backer plate  14  and the rear backer plate  10  are typically essentially identical. 
         [0027]    At an intersection of the rear backer plate flange portion and the front backer plate flange portion  16 , and the front backer plate axially extending portion  18 , there is a continuous weld seam  26  to hold the first rear backer plate front rear backer plate together. A weld seam  27  can also be provided in the flange portion of the backer plates. Some embodiments with the weld seam  27  will omit the weld seam  26 . The first rear backer plate  14  and the front backer plate when welded together form an arcuate first shell  28  providing an arcuate clam shell shaped chamber. 
         [0028]    Clutch brake  7  has a second arcuate shell  40 . Second arcuate shell  40  has a rear backer plate  44  and a front backer plate  46 . The second rear backer plate  44  and the front backer plate  46  typically are stamped from the same material as the first rear backer plate  10 . Typically the second rear backer plate  44  and the second front backer plate  46  will be welded together as previously described with the first arcuate shell  28 . Also, backer plate  44  and  46  also have friction linings  12  as previously described. 
         [0029]    A hinge connection  52  is provided to pivotally connect the first and second arcuate shells  28  and  40  together. The first arcuate shell front backer plate has a hinge portion  54  axially spaced or separated from a rear backer plate hinge portion  56 . A hinge portion  58  of the second rear backer plate and a hinge portion  60  of the second front backer plate are axially positioned adajacent to one another and are captured between the hinge portions  54  and  56  of the first arcuate shell. A hinge pin  62  is provided having a head  64  that abuts hinge portion  54 . The hinge pin  62  has a shank  66  that extends through apertures in the hinge portions  54 ,  58  and  60 . The pin shank  66  is weldably connected to hinge portion  56  of the first rear backer plate. A slight clearance is made in the axial stack-up of the hinge portions to allow for ease of pivotal movement between the arcuate shells  28  and  40 . 
         [0030]    Clutch brake  7  has first and second arcuate inner collars  70 . Inner collars  70  have inwardly extending tabs  72 . Tabs  72  are provided for interconnection with axial grooves provided in a transmission input shaft (not shown). Therefore the inner collars  70  turn with the transmission input shaft. The inner collars  70  outer periphery  74  is incased in the chambers provided by the arcuate shells  28  and  40 . Clutch brake  7  has first and second outer collars (sometimes referred to as tang washers)  78 . Outer collars  78  are positioned radially outward of the inner collars  74 . The outer collars  78  have radially inward extending arms  82  which capture extreme ends  84  of the inner collars. The outer collars  78  circumferentially interconnect with the inner collars  74  so that the outer collars  78  and the inner collars  74  rotate together. The outer collars have tongue and groove  86 ,  88  to insure for proper alignment of the outer collars during assembly of the clutch brake  7 . The outer collar  78  is axially thinner than the inner collar  74 . The inner collar  74  has an axial thickness slightly less than an interior axial distance between the front and rear backer plates of the arcuate shells  28 ,  40 . 
         [0031]    The clutch plate  7  has wave springs  90  and  91 . The wave spring  90  has two coplanar portions  92  that are 90° apart. The wave spring  90  has 1.6 undulations or waves. The wave spring  90  has a radially outward extending restraining tab  94  that fits within a slot  96  of the front backer plate to fix the spring&#39;s position with respect to the first front backer plate  14 . The tab  94  is arcuately off-centered so as to prevent incorrect installment of the spring  90  with the backer plate  14  (upside down or on the wrong backer plate). A tab  95  on spring  91  is also off-center. The springs  90 ,  91  bias the outer collars  78  into an interior surface of the rear backer plates  10 ,  44 . 
         [0032]    The first front backer plate  14  has stamped protrusions  102 . Stamped protrusions  102  contact ends  97  of the spring  90  (Note in  FIGS. 3  ends of the spring are not contacting the protrusions  102  for purposes of illustration). The protrusions insure the ends  97  of the spring do not engage with the outer collars  78 . 
         [0033]    To hold the arcuate shells  28 ,  40  together there is provided a weld nut  104 . The weld nut  104  has a threaded aperture  106  that is orientated normal to a central axis of the clutch brake  7 . The weld nut  104  has a tongue  108  fitted within a slot  110  that is in the second rear backer plate  44  generally opposite the hinge connection  50 . The weld nut  104  has a main body with lateral extensions  112 . A portion of the lateral extensions  112  is welded to the rear backer plate generally lateral of the tongue  108 .  FIG. 6  illustrates the weld beads  114  that connect the weld nut  104  to the second rear backer plate  44 . The second rear backer plate  44  also has a bent arm  120  which further secures the weld nut  104 . Aligned with the threaded aperture  106  is an eyelet  124  provided by the first front backer plate  14 . The eyelet  124  accepts a headed threaded fastener  130  which connects the arcuate shells  28  and  40  together. Opposite the tongue  108 , the weld nut has a mound protrusion  140 . The mound protrusion  140  can be accepted by an opening  142  provided in the first front backer plate  14 . The opening  142  has a snap fit relationship with the mound  140  providing a detent to keep the arcuate shells  28 ,  40  together until the threaded fastener  130  is installed for permanent installation. As best shown in  FIG. 8  when the arcuate shells are placed together there exists a gap  150  between the two front backer plates  14  and  46 . 
         [0034]    In operation the arcuate shells  28  and  40  are opened, placed upon the transmission shaft so that the tabs  72  are connected with the axial grooves of the transmission shaft. The shells are closed, the detent mechanism holds the shells closed until the fastener  130  is installed into the weld nut threaded aperture  106 . If in operation excessive torque in placed on the clutch brake the inner and outer collars  70  and  78  will rotate with respect to the arcuate shells  28  and  40  to limit the torque. If it is desired to change the level of limitation of the torque on the clutch brake  7 , a substitution of springs with a different spring constant can be made. An advantage of the wave spring is that it allows the clutch brake to be thinner than clutch brakes with coil springs. Additionally, notches  13  are provided so that a chisel or other instrument which is inserted through an inspection port of the bell housing can rotate the arcuate shells  28  and  40  with respect to the inner and outer collars or to move the weld nut to a position best suited for removal. 
         [0035]      FIGS. 16 through 20  provide alternate preferred embodiments of the hinge portion of the clutch brake. Referring to  FIG. 16  a hinged connection  152  has a hollow rivet  163  with its base welded to a hinge portion  156  of the first rear backer plate. Hinge portion  158  of the second rear backer plate and hinge portion  160  of the second front backer plate have a clearance with the side of the hollow rivet  163 . A hinge portion  154  of the first front backer plate axially captures the hinge portions  158 ,  160  of the second rear and front backer plates. The hinge portion  154  also has a slight clearance with the head of the pin  162 . A shank of the pin  162  is press fitted within the interior of the hollow rivet  163 . 
         [0036]    Referring to  FIG. 17  a hinge connection  252  is provided. In hinge connection  252  a second rear backer plate hinge portion  260  has a deep draw leg  255 . Leg  255  is press fitted about pin  262 . Second front backer plate hinge portion  258  has a hinge portion with an enlarged aperture to accommodate the leg  255 . A first backer plate rear portion  254  has clearance with the leg  255  as well as a first front backer plate hinge portion  256  which additionally has clearance with a step portion of the pin  262  as well as with head of the pin  262 . 
         [0037]    Referring to  FIG. 18 , hinge connection  352  is provided having a pin  362 . Pin  362  is press fitted within the apertures of the second rear backer plate hinge portion  358  and of the second front backer plate hinge portion  360 . Hinge portions  356 ,  354  of the first rear and front backer plate hinge portions respectively have apertures with a clearance with the pin  362 . Hinge portion  354  has a clearance underneath the head of the pin  362 . 
         [0038]    Referring to  FIG. 19  hinge connection  452  is provided having a pin  462 . A first front backer plate hinge portion  454  has a bent or drawn leg  457 . A first rear backer plate hinge portion  456  has an enlarged aperture to accommodate the leg  457 . A second rear backer plate hinge portion  458  has a upturned leg  459  which is press fitted with the pin  462  and also has a radial clearance with the leg  457 . A second front backer plate hinge portion  460  has an enlarged aperture to accommodate the leg  459 . The head of the pin has a slight clearance with the hinge portion  454  of the first front backer plate. 
         [0039]    Referring to  FIG. 20  hinge connection  552  is provided. Hinge connection  552  has a first front hinge portion  554  with a bend leg  555  with an outward extending flange  557  connected thereto. The flange  557  captures the first rear backer plate hinge portion  556  and has radial clearance and axial clearance with hinge portions  560 ,  558  of the second front and rear backer plates to allow pivotal movement. 
         [0040]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.