Abstract:
A parking brake release mechanism includes a brake handle having a longitudinal axis. A release cable is disposed at least partially in the brake handle and a push button actuator is positioned to be accessed from a tip of the handle for actuating the release cable. The push button actuator preferably moves lineally with respect to the longitudinal axis of the handle for locking and unlocking the brake component. The release cable is flexible and biased between two positions to form a push-pull cable actuator.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority of U.S. Provisional Patent Application Ser. No. 60/738,260 filed Nov. 18, 2005, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to park brake release mechanisms.  
       BACKGROUND OF THE INVENTION  
       [0003]     Park brake release mechanisms are known in the art. Typical release mechanisms include pull release mechanisms where an operator pulls a handle attached to a cable to unlock a park brake that has been engaged. Another known release mechanism includes a hand lever type release that is moved about a pivot to engage and disengage the park brake. The lever includes a button that is depressed to allow movement of the lever to engage and disengage the park brake.  
         [0004]     Such brake levers include rod linkages coupled to the button to actuate the release mechanism and allow an operator to move the lever. The rod mechanisms contribute to the overall cost and complexity of a release mechanism, as well as adversely affect the packaging size and configuration of a release mechanism. Additionally, rod actuated release mechanisms may adversely affect the noise vibration and harshness of the release mechanisms.  
         [0005]     There is therefore a need in the art for a release mechanism that eliminates the need for complex rod linkages and has an improved noise vibration and harshness performance. There is also a need in the art for a release mechanism that has a push button release that moves lineally with respect to a release cable allowing connection to a cable directly. Also, there is a need in the art for a release mechanism that is cost effective and can be used on a variety of park brake systems. Finally, there is a need in the art for a release mechanism that improves the packaging of such systems and can be used on various brake levers, brake pedals and vehicle mounted push button release applications.  
       SUMMARY OF THE INVENTION(S)  
       [0006]     In a first aspect there is disclosed a parking brake release mechanism that includes a release cable including a strand having first and second portions. A release actuator is connected at the first portion of the strand. A brake component is connected to the second portion of the strand. The release actuator is positioned and connected to the strand to move lineally relative to the strand for locking and unlocking the brake component.  
         [0007]     In a second aspect there is disclosed a parking brake release mechanism that includes a brake handle having a longitudinal axis. A release cable is disposed at least partially in the brake handle and a push button actuator is positioned to be accessed from a tip of the handle for actuating the release cable. The push button actuator maybe connected to the first portion of the strand. A brake component maybe coupled to the second portion of the strand. The push button actuator preferably moves lineally with respect to the longitudinal axis of the handle for locking and unlocking the brake component. In a preferred embodiment the strand is flexible and biased between two positions to form a push-pull cable actuator.  
         [0008]     In a third aspect there is disclosed a parking brake release mechanism that is moveable between locked and unlocked positions. The parking brake release mechanism includes a release cable including a strand having first and second portions. A release actuator is coupled to the first portion of the strand. The release actuator includes a first biasing member biasing the parking brake release mechanism to the locked position. A brake component is coupled to the second portion of the strand. The brake component includes a second biasing member biasing the parking brake release mechanism to the unlocked position. The first biasing member has a greater biasing force than the second biasing member such that the parking brake release mechanism is biased toward the locked position until an external force is applied to the first biasing member allowing movement of the strand toward the unlocked position in response to the biasing force of the second biasing member. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is an exploded perspective view of a brake assembly including the park brake release mechanism of the present invention;  
         [0010]      FIG. 2  is a partial perspective view of a release actuator in the locked position;  
         [0011]      FIG. 3  is a perspective view of a release actuator in the unlocked position;  
         [0012]      FIG. 4  is a perspective view of a release actuator without the release housing detailing engagement of the first spring with the release member;  
         [0013]      FIG. 5  is a perspective view of a brake component including a pawl and sector in the locked position;  
         [0014]      FIG. 6  is a perspective view of a brake component including a pawl and sector in the unlocked position;  
         [0015]      FIG. 7  is a perspective view of an alternative embodiment of a release mechanism having a brake handle having an integrally formed release housing;  
         [0016]      FIG. 8  is a side view alternative embodiment of a brake component including a pawl and sector;  
         [0017]      FIG. 9  is a perspective view alternative embodiment of a brake component including a pawl and sector;  
         [0018]      FIG. 10  is a perspective view of an alternative embodiment of a release mechanism having an integral push button and release member;  
         [0019]      FIG. 11  is a perspective view of the cable strand and release member of  FIG. 10 ;  
         [0020]      FIG. 12  is a perspective view of an alternative embodiment of a release mechanism having a push button and clutch actuated brake;  
         [0021]      FIG. 13  is a block diagram of a parking brake assembly. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     Referring to  FIGS. 1 and 13 , there is shown one embodiment of a brake assembly  5  including a parking brake release mechanism  10 . The parking brake assembly  5  includes a main actuator assembly, such as a main cable  7  which controls a brake on a wheel  6  of a vehicle. This main cable  7  is distinguished from a release cable  15  that is not directly linked with the brake on a wheel  6 , but is associated with a release mechanism  10 .  
         [0023]     The parking brake release mechanism  10  is movable between locked and unlocked positions and includes a release cable  15  having a strand  17  having first and second portions  20 ,  25 . A release actuator  30  is coupled to the first portion  20  of the strand  17  and moves lineally with respect to the strand  17 . A brake component  40  is coupled to the second portion  25  of the strand  17 .  
         [0024]     A first biasing member  35  positioned at the first portion  20  of the strand  17 , with a spring being shown although other biasing members may be utilized, biases the parking brake release mechanism  10  to the locked position. A second biasing member  45 , with a spring being shown although other biasing members may be utilized, is positioned at the second portion of the strand  17  and biases the parking brake release mechanism  10  to the unlocked position. The first biasing member  35  has a greater biasing force than the second biasing member  45  such that the parking brake release mechanism  10  is biased toward the locked position until an external force is applied to the first biasing member  35  allowing movement of the strand  17  toward the unlocked position in response to the biasing force of the second biasing member  45 .  
         [0025]     One embodiment of the brake assembly  5 , as detailed in  FIG. 1  includes a mounting bracket  50  that is attached to a vehicle body. As shown, the embodiment is a hand brake; however, such a system could be modified to be a footbrake. A brake handle assembly  55  including a handle housing  60  is pivotally attached to the mounting bracket  50 . The handle assembly has a longitudinal axis and includes a tube  65  connected to the handle housing  60 . A handle grip  70  is disposed on an upper portion of the handle tube  65 . The handle grip  70  includes a grip housing  75  disposed within the grip  70  and coupled to the handle tube  65 . The handle grip  70  also includes a tip at the end of the handle grip.  
         [0026]     The parking brake release mechanism  10  includes the release cable  15  at least partially disposed within the handle grip  70  and handle tube  65 . As stated above, the release cable  15  includes a strand  17  having a first portion  20  coupled to the release actuator  30  and a second portion  25  coupled to the brake component  40 .  
         [0027]     Referring to  FIGS. 2 and 3 , there is shown one embodiment of a release actuator  30  that may be utilized by the present invention. The release actuator  30  includes a release housing  80  disposed within the grip housing  75 . A release member  85  is positioned within the release housing  80  and is capable of movement longitudinally within the release housing  80 . The first biasing member  35  is positioned about the release member  85  and biases the release member  85  toward the locked position, as shown in  FIG. 2 . The release actuator  30  may also include an end cap  90  positioned about a first portion  95  of the release member  85  that may be depressed by an operator of the vehicle to compress the first biasing member  35 . The end cap  90  may alternatively be a push button as will be described in more detail below.  
         [0028]     Referring to  FIG. 4 , there is shown the release member  85  and first biasing member  35  without the release housing  80 . The release member  85  includes a first portion  95  that is adapted to engage the end cap  90 , as described above. The first portion  95  of the release member  85  also includes a guide portion  100  having a rectangular cross section in the pictured embodiment although other shapes may be utilized. The guide portion  100  also includes a spring arm  105  having a stop  110  that is received within a notch  115  formed in the release housing  80 , as best shown in  FIGS. 2 and 3 . The stop  110  travels within the notch  115  and limits the amount of travel of the release member  85  within the release housing  80  to prevent excess compression of the first biasing member  35 , as well as determine the amount of travel of strand  17 . The release member  85  also includes a biasing member engaging portion  120  extending longitudinally from the guide portion  100 . The biasing member engaging portion  120  includes a second portion  125  that is adapted to engage a fitting associated with the first portion  20  of the strand  17 .  
         [0029]     As can be seen in  FIG. 4 , the first biasing member  35  is positioned about the biasing member engaging portion  120  of the release member  85 . The first biasing member  35  includes a first portion  130  that abuts a face  135  defined by the transition from the guide portion  100  to the biasing member engaging portion  120  of the release member  85 . The second portion  140  of the first biasing member  35  abuts an end face of one of a series of separated walls  126  formed on the interior of the release housing  80 . The first biasing member  35  biases the release member  85  toward the locked position shown in  FIG. 2 .  
         [0030]     As best seen in  FIGS. 2 and 3 , the series of separated walls  126  define notches  128  tat engage a conduit fitting  145  positioned at the first portion  20  of the release cable  15 . The series of separated walls  126  allow the conduit fitting  145  to be adjusted to different positions to adjust the length of the cable  15 . The conduit fitting  145  may be positioned in any of the notches  128  to take up or pay out the cable  15  as needed.  
         [0031]     The parking brake release mechanism  10  may also include a brake component  40 , detailed in  FIGS. 5 and 6 , that is coupled to the second portion  25  of the strand  17 . The brake component  40  in the depicted embodiment includes a pawl  150  that is pivotally coupled to the handle housing  60 . The pawl  150  includes a first portion  155  that is adapted to engage a sector  160  connected with the mounting bracket  50 . The pawl  150  also includes a second portion  165  that includes a connection portion  170  that is sized and shaped to engage an end fitting  175  associated with the second portion  25  of the strand  17 . In one aspect, the end fitting  175  is received within the connection portion  170  and a retainer clip  182  is positioned about the pawl  150  and engages the end fitting  175  to securely retain the end fitting  175  within the connection portion  170  of the pawl  150 . It should be realized that alternative structures for attaching the strand  17  to the pawl  150  may be utilized. The pawl  150  also includes a pair of notches  180  formed about the connection portion  170  that are sized and positioned to allow the second biasing member  45  to seat against the pawl  150  at a first portion  185  of the second biasing member  45 . As can be seen in  FIGS. 5 and 6 , the second biasing member  45  is disposed about the connection portion  170  of the pawl  150  and is seated within the notches  180  formed on the pawl  150  at a first portion  185  of the second biasing member  45 . A second portion  190  of the second biasing member  45  engages a cable fitting  195  associated with the second portion  25  of the release cable  15  or alternatively could associate with any fixed flange or surface. The cable fitting  195  is fixed using any suitable structure. In the depicted embodiment, the cable fitting  195  is mounted on a tab  200  that extends from the handle housing  60 . In this manner, the second biasing member  45  is retained and applies a biasing force to the pawl  150  for pivotal movement of the pawl  150  about the handle housing  60 .  
         [0032]     In use, an operator presses on the end cap  90  causing the release member  85  to travel within the release housing  80  a specified distance, as determined by the length of the notch  115  formed in the release housing  80  that engages the tab  110  formed on the release member  85 . As a result of movement of the release member  85  from the locked position shown in  FIG. 2  to the unlocked position shown in  FIG. 3 , the first biasing member  35  is compressed allowing movement of the strand  17  against the otherwise present biasing force of the first biasing member  35 .  
         [0033]     At the second portion  25  of strand  17 , the second biasing member  45  is compressed in the locked position, as shown in  FIG. 5 , due to the greater force of the first biasing member pulling the strand  17  toward the first portion  20  and causing pivotal movement of the pawl  150  such that it engages the sector  160  preventing pivotal movement of the handle housing  60  about the mounting bracket  50 . When the release member  85  is moved from the locked position shown in  FIG. 2  to the unlocked position shown in  FIG. 3 , the second biasing member  45  is then free to expand, as shown in  FIG. 6 , causing pivotal movement of the pawl  150  with respect to the handle housing  60 . In this manner, the pawl  150  disengages the sector  160  allowing for pivotal movement of the handle housing  60  about the mounting bracket  50 . As stated above, the balance of spring forces where the first biasing member  35  has a greater biasing force than the second biasing member  45  allows for the release mechanism  10  to be maintained in the locked position until an external force is applied compressing the first biasing member  35  and allowing the stored energy within the second biasing member  45  to pivot the pawl  150  away from the sector  160  allowing pivotal movement of the handle housing  60  with respect to the mounting bracket  50 .  
         [0034]     In an alternative embodiment shown in  FIG. 7 , the handle grip  370  may include an integrally formed release housing  380 . Similar to the above described embodiment, the release actuator moves lineally with respect to the strand  17 . As with the previously described embodiment, the release housing  380  may include the series of separated walls  126  defining notches  128  that engage a conduit fitting  145  positioned at the first portion  20  of the release cable  15  or the release housing  380  may include a single notch for attaching to the conduit fitting  145 . However, the release member  385  may be of a different configuration than that previously described. The release member  385  may be similar to that depicted in  FIG. 11 . The release member  385  shown in  FIG. 11  includes a push button portion  390  and a guide portion  300 . The first portion  20  of the strand  17  is connected to the guide portion  300  of the release member  385 . The first biasing member  35  associates with an end face  340  of the release member  385  at the first portion of the biasing member  35  and associates with a face of the series of separated walls  126  at a second portion of the biasing member  35 . The strand  17  passes through the biasing member  35  to connect with the guide portion  300 . The alternative embodiment operates in the same manner as that described above.  
         [0035]     Another alternative embodiment of a release mechanism  10  is shown in  FIGS. 8 and 9 . In the depicted embodiment the cable end fitting  195  is at the second portion  25  of the strand  17  associated with the brake component  40 . As with the previously described embodiment the brake component  40  may include a pawl  150  and sector  160 . The second biasing member  45  acts as above and biases the pawl  150  out of engagement from the sector  150  when a force is applied overcoming the first biasing member  35 . The second biasing member  45  is seated on the pawl  150  and the end fitting  195 , as described above. However, the end fitting  195  includes a series of separated walls  416  that define notches  418 . A fixed clip  444 , as best shown in  FIG. 9  can engage different notches  418  to adjust a length of the cable  15 . The series of notches  418  may be used with or with out the series of notches  118  described above at the first portion  20  of the strand  17  to adjust the cable length at either portion of the cable  15 .  
         [0036]     Another alternative embodiment is shown in  FIGS. 10 and 11 . The release housing  580  is similar to that described above in  FIG. 7  except that it is not integrally formed with the handle  70 . The release member  385  is the same as that described above with the respect to  FIG. 11  and includes a push button portion  390  and a guide portion  300 . The first portion  20  of the strand  17  is connected to the guide portion  300  of the release member  385 . The first biasing member  35  associates with an end face  340  of the release member  385  at the first portion of the biasing member  35  and associates with an end face of the release housing  580  at the second portion of the first biasing member  35 . The embodiment shown in  FIG. 10  includes a single notch  550  formed in the release housing  580  to receive a conduit end fitting  545 . The conduit end fitting  545  includes a contact portion  560  for pushing it into the notch  550 .  
         [0037]     Referring to  FIG. 12  there is shown another alternative embodiment. The release actuator  30  is a push button actuator that is disposed on a surface of a vehicle. In one aspect the push button  600  may be positioned on a control panel of a vehicle. The first portion of the strand  17  is connected to the push button  600 . A first biasing member  35  associates with the push button  600  at a first portion of the first biasing member  35  and associates with an engagement surface  605  at a second portion of the first biasing member  35  for moving the release mechanism  10  to a locked position. The brake component  40  includes a clutch  610  moveable to lock and unlock the release mechanism  10 . The clutch  610  includes a lever  620  connected to the second portion of the strand  17 . The second portion of the cable includes a fixedly retained conduit fitting  695  similar to that described above. A second biasing member  45  has a first portion associating with the lever  620  and a second portion associating with a face of the conduit end fitting  695  for moving the release mechanism  10  to the unlocked position. As with the previously described embodiment of  FIGS. 8 and 9  a length of the cable can be adjusted by positioning in various notches  618  formed in the conduit fitting  695 .  
         [0038]     While the parking brake release mechanism  10  has been described with respect to various brake assemblies including a pawl  150  that engages a sector  160 , other parking brake designs may be utilized with the release mechanism  10  of the present invention. For example, the parking brake release mechanism  10  having a first biasing member  35  having a greater biasing force than a second biasing member  45  disposed on opposing portions of a release cable  15  may be used on both self adjust and manual adjust designs, as well as torsion lock designs. U.S. Pat. Nos. 5,588,335; 5,309,786; 5,832,784; 5,907,977 disclose torsion lock designs and are commonly owned by the assignee of the present application and are herein incorporated by reference. The torsion lock design may utilize a release cable  15  in the same manner described with respect to the pawl  150  and sector  160  design disclosed above. In such a design, the first biasing member  35  again would have a greater force than a second biasing member  45  associated with the torsion lock of the brake assembly. In such a design, an external force exceeding the first biasing member  35  would need to be applied to allow the biasing force of the second biasing member  45  to release the torsion lock allowing for actuation of a parking brake.  
         [0039]     The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.