Abstract:
Pin release mechanism comprising: a release pin axially movable from a first position to a second position; a bias spring biasing the release pin towards the second position; a pull rod interacting with ball bearings, the pull rod having a locked position in which ball bearings radially interfere with movement of the release pin and prevent movement of the release pin from the first position to a second position, and an unlocked position in which the ball bearings may move radially relative to the pull rod to allow the release pin to move from the first position towards the second position; a solenoid, which when actuated moves the pull rod toward the unlocked position; and a bias pin coupled to the pull rod, biased by a spring pushing between the release pin and the bias pin, to bias the bias pin and the pull rod toward the second, unlocked direction.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention pertains to the field of pin mechanisms. More particularly, the invention pertains to a pin mechanism for a fire extinguisher. 
         [0003]    2. Description of Related Art 
         [0004]      FIGS. 1-2  show a prior art solenoid actuator in a released position and an unreleased position respectively. 
         [0005]    The solenoid actuator has a housing  101  with a first bore  102  for slidably receiving a release pin  117  and a second bore  120  for receiving a solenoid assembly  121 . 
         [0006]    The release pin  117  has a collar  122  that slides along the surface of the first bore  102  of the housing  101  and a shaft portion  123  that is slidably received within a cap  103  closing off the first bore  102  of the housing  101 . A release spring  106  is present between the release pin  117  and the cap  103 . 
         [0007]    Between the collar  122  and the shaft portion  123  of the release pin  117  is a neck portion  124 . A ramp section or angled surface  125  is present between the collar  122  and the neck portion  124  of the release pin  117 . 
         [0008]    Slidably received within an open bore  107  of the neck portion  124  of the release pin  117  is a detent retainer  114 . The detent retainer  114  has an inner surface defining a bore  118  for receiving a release spool  109 . The inner surface of the bore  118  of the detent retainer  114  includes a straight surface  126  which is connected to an angled ramp section  119 . 
         [0009]    The release spool  109  has a cavity  127  which receives a first ball bearing  115   a  attached to a second ball bearing  115   b  through a retention spring  116 . The release spool  109  is also coupled to a first end  113   a  of a push rod  113 . 
         [0010]    The solenoid assembly  121  received within the second bore  120  of the housing  101  includes at least one coil  111  connected to a power source (not shown), a solenoid spool  110 , and a moveable armature  112 . Connected to the moveable armature  112  is a second end  113   b  of a push rod  113 . 
         [0011]    In the unreleased position, as shown in  FIG. 2 , the collar  122  of the release pin  117  is not in contact with the end of the first bore  102  and the release spring  106  is compressed between the collar  122  of the release pin  117  and the cap  103 . The release pin  117  is maintained in this position by the first and second ball bearings  115   a,    115   b  engaging the angled surface  125  of the collar  122  of the release pin  117  and the flat surface  126  of the detent retainer  114 . The first and second ball bearings  115   a,    115   b  are held against the angled surface  125  of the collar  122  and the straight surface  126  of the detent retainer  124  by the retention spring  116 . 
         [0012]    To move the solenoid actuator to a released position as shown in  FIG. 1 , at least one coil  111  of the solenoid assembly  121  is energized and pulls the armature  112  away from the cap  103 . Movement of the armature  112  moves the push rod  113  away from the cap  103 , pulling the release spool  109  away from the cap  103 . The movement of the release spool  109  allows the first and second ball bearings  115   a,    115   b  to travel from the straight surface  126  of the detent retainer  114  to the ramp section  119  of the detent retainer  114 , compressing the retention spring  116  between the ball bearings  115   a,    115   b.  The movement of the first and second ball bearings  115   a,    115   b  to the ramp section  119  of the detent retainer  114  removes any force on the collar  122  of the release pin  117 , allowing the release spring  106  to move the release pin  117  to a position where the collar  122  is in contact with the end of the first bore  101 . 
         [0013]    The solenoid actuator of  FIGS. 1-2  is resettable by moving the shaft portion  123  of the release pin  117  in a direction away from the solenoid assembly  121 . The movement of the shaft portion  123  of the release pin  117  in this direction allows the retention spring  116  to bias the ball bearings  115   a,    115   b  outwards to contact the ramp section  125  of the detent retainer  114  and to eventually come in contact with the angled surface  125  of the collar  122  of the release pin  117  as shown in  FIG. 2 . 
         [0014]    It should be noted that there is not a bias force that acts directly on the push rod  113  that moves the armature  112  of the solenoid assembly  121 . 
         [0015]      FIG. 3  shows another prior art solenoid actuator in an unreleased position. The solenoid actuator has a housing  201  with a first bore  202  for slidably receiving a release pin  217  and a second bore  220  for receiving a solenoid assembly  221 . 
         [0016]    The release pin  217  has a collar  222  that slides along the inner surface of the first bore  202  of the housing  201  and a shaft portion  223  that is slidably received within a cap  203  closing off the first bore  202  of the housing  201 . A release spring  206  is present between the release pin  217  and the cap  203 . 
         [0017]    Between the collar  222  and the shaft portion  223  of the release pin  217  is a neck portion  224 . A ramp section or angled surface  225  is present between the collar  222  and the neck portion  224  of the release pin  217 . 
         [0018]    Slidably received within an open bore  207  of the neck portion  224  of the release pin  217  is a detent retainer  214 . The detent retainer  214  has an inner surface defining a bore  218  for receiving a release spool  209 . A circumferential groove  230  with straight edges  231  present along an outer surface of the detent retainer  214  and receive ball bearings  215 . A compression spring  232  is present between the detent retainer  214  and the release spool  209 , linking the detent retainer  214  to the release spool  209 . 
         [0019]    On the outer circumference of the release spool  209  is a groove section  234  including a ramp  235  between two straight surfaces  240 ,  241 . The ball bearings may travel from straight surface  240  to the ramp  235  and come to rest on straight surface  241  as the release spool  209  slides within the bore  218  of the detent retainer  214 . The detent retainer  214  is also coupled to a first end  213   a  of a push rod  213 . 
         [0020]    The solenoid assembly  221  includes at least one coil  211  connected to a power source (not shown), a solenoid spool  210 , a moveable armature  212  and a stop  236 . The second end  213   b  of the push rod  213  is connected to the moveable armature  212  and is slidably received by the stop  236 . The movement of the armature  212  towards the release pin  217  is limited by the stop  236 . Another compression spring  237 , with the same spring force as the compression spring  232  between the detent retainer  214  and release spool  209  is present between the moveable armature  212  and the second bore  220  of the housing  201 . 
         [0021]    In an unreleased position, the collar  222  of the release pin  217  is not in contact with the end of the first bore  202  and the release spring  206  is compressed between the collar  222  of the release pin  217  and the cap  203 . The release pin  217  is maintained in this position by the ball bearings  215  engaging the angled surface  125  of the collar  222  of the release pin  217 , a straight edge  231  of the detent retainer  214 , and a straight surface  240  of the groove section of the release spool. 
         [0022]    To move the solenoid actuator to a released position (not shown), at least one coil  211  of the solenoid assembly  221  is energized and pushes the armature towards the cap  203 . The movement of the armature  212  moves the push rod  213  towards the cap  203 , pushing the detent retainer  214  and the release spool  209  towards the cap  203 . The movement of the detent retainer  214  and the release spool  209  allows the ball bearings  215  to travel from the straight surface  240  to the ramp  235  and come to rest on straight surface  241  of the release spool  209 . The movement of the ball bearings  215  to the ramp  235  of the release spool  209  removes any force on the collar  222  of the release pin  217 , allowing the release spring  206  to move the release pin  217  to a position where the collar  222  is in contact with the end of the first bore  202 . 
         [0023]    The spring  232  between an end of the second bore  220  and the armature  212  provides a source of bias or spring force on the armature  212  that is specifically counteracted by the spring force of the spring  237  present between the release spool  209  and detent retainer  214 . Therefore, a spring force that is in the direction of armature  212  movement that is not counteracted is not present. 
       SUMMARY 
       [0024]    According to an embodiment of the present invention, a pin release mechanism. The pin release mechanism comprising: a release pin axially movable from a first position to a second position; a bias spring biasing the release pin towards the second position; a pull rod interacting with a plurality of ball bearings, the pull rod having a locked position in which a plurality of ball bearings radially interfere with movement of the release pin and prevent movement of the release pin from the first position to a second position, and an unlocked position in which the plurality of ball bearings may move radially relative to the pull rod to allow the release pin to move from the first position towards the second position; a solenoid, which when actuated moves the pull rod toward the unlocked position; and a bias pin coupled to the pull rod, biased by a spring pushing between the release pin and the bias pin, to bias the bias pin and the pull rod toward the second, unlocked direction. 
         [0025]    The present invention utilizes stored energy to achieve high forces across long distances while using relatively small packaged size solenoids. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIGS. 1-2  show a released and an unreleased position of a prior art actuator. 
           [0027]      FIG. 3  shows an unreleased position of another prior art actuator. 
           [0028]      FIG. 4  shows a schematic of a pin mechanism in an unreleased position. 
           [0029]      FIG. 5  shows a schematic of a pin mechanism in a released position. 
           [0030]      FIG. 6  shows an exploded view of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]      FIGS. 4-6  show a pin mechanism for releasing a pin. The pin mechanism of the present invention allows for high force values to be achieved over longer strokes with the use of an optimized solenoid package size. In one embodiment, the pin mechanism is preferably used for releasing a pin of a fire extinguisher. 
         [0032]    The pin mechanism of the present invention has a spring housing  1  with a bore  12 . Slidably received within the first end of the bore  12  is a release pin  10  with a head portion  20  connected to a shaft portion  22  through a neck portion  21 . Extending from the head portion  20  of the release pin  10  is a bias spring retainer  11 . The bias spring retainer  11  is threaded and locked into a pin (not shown) of fire extinguisher for example. A portion of the bias spring retainer  11  also extends within a bias spring bore  23  in the neck portion  21  of the release pin  10 . The bias spring bore  23  is connected to a cavity  24  that extends a length of the shaft portion  22  of the release pin  10 . A compressed bias spring  9  is present within the bias spring bore  23  with a first end of the spring  9   a  in contact with the bias spring retainer  11  and the second end  9   b  of the bias spring  9  in contact with a pin guide  8  slidable received within the bias spring bore  23 . Integrally connected to the pin guide  8  is a bias pin  7  which extends a portion of the length of the cavity  24  of the shaft portion  22  of the release pin  10 . An end of the shaft portion  22  is slidably received by a bore  25  defined by a spring guide  3 . 
         [0033]    A release spring  2  surrounds the neck portion  21  and shaft portion  22  of the release pin  10 , with a first end  2   a  of the release spring  2  in contact with the head portion  20  of the release pin  10  and a second end  2   b  of the release spring  2  in contact with a spring guide  3 . The release spring  2  moves the release pin  10  outward from the housing  1 , or away from the solenoid assembly  50  while the second end  2   b  of the release spring  2  remains stationary and in contact with the spring guide  3 . The spring guide  3  prevents the pull rod  6  from ever contacting the release spring  2 , regardless of the position of the pull rod  6 . 
         [0034]    Within a second end of the bore  12  is a solenoid assembly  5 . The solenoid assembly  5  includes at least one coil  13  connected to a power source (not shown), a bobbin  30 , and a moveable armature  14 . The moveable armature  14  receives a pull end  17  with an integrally connected a tab  18  of a pull rod  6 . Opposite of the pull end  17  of the pull rod  6  is a rod end  16  which is received by the bore  25  of the spring guide  3  and within the cavity  24  of the shaft portion  22 . The pull end  17  of the pull rod  6  has a first outer diameter portion D 1  and the rod end  16  of the pull rod  6  has a second outer diameter portion D 2 . The transition between the first outer diameter portion D 1  and the second outer diameter portion D 2  is made through a ramp section  32  of the pull rod  6 . The first outer diameter portion D 1  is greater than the second outer diameter portion D 2 . At least two ball bearings  4  slide from the first outer diameter portion D 1 , down the ramp section  32  to the second outer diameter portion D 2  as the pull rod  6  is moved from an unreleased position to a released position. 
         [0035]      FIG. 6  shows an exploded view of a portion of  FIG. 4  indicated by the dashed circle. The release spring  2  remains compressed by a frictional force F S  transmitted through the ball bearings  4  that are positioned between the pull rod  6 , release pin  10  and the spring guide  3 . In the unreleased position, the release pin  10 , while compressed, is generating a force that is trying to pull the entire release pin  10  outward, this force vector creates a horizontal reaction force F F , parallel to a main axis, at the ramp section  33  located on the spring guide  3 . The main axis is the axis in which the pull pin  6  is moved along. The vertical component or force perpendicular to the main axis of this force vector F R  acting upon the ball bearings  4  via the slope of the surface  33  creates a frictional force that inherently locks the release spring  2  in the compressed position. 
         [0036]    When the pin mechanism is in the unreleased position as shown in  FIG. 4 , the head portion  20  of the release pin  10  is not in contact with the end of the bore  12  of the spring housing  1  and the release spring  2  is compressed. The rod end  16  of the pull rod  6  biases the bias pin  7  and the pin guide  8  within the bias spring retainer  11 , further compressing the bias spring  9 . At least two ball bearings  4  are held in place on the first outer diameter portion D 1  of the pull rod  6  by friction seating on both the spring guide  3  ramp section  33  and the surface  34  of the shaft portion  22  of the release pin  10 . 
         [0037]    To release the pin mechanism from a released position to an unreleased position as shown in  FIG. 5 , at least one coil  13  is energized and pulls the armature  14  towards the solenoid assembly  50 , pulling the tab  18  of the pull end  17  of the pull rod  6  towards the solenoid assembly  50 . The movement of pull rod  6  towards the solenoid assembly  50  is aided by the force of the bias spring  9  within the bias spring retainer  11 , biasing pin guide  8  and bias pin  7  against the rod end  16  of the pull rod  6 . 
         [0038]    The movement of the pull rod  6  towards the solenoid assembly  50  allows at least two ball bearings  4  to move from the first outer diameter portion D 1 , of the pull rod  6  down the ramp section  32  of the shaft portion  22  of the release pin  10 , to the second outer diameter portion D 2  of the pull rod  6 , and simultaneously off of the ramp section  33  of the spring guide  3  and surface  34  of the shaft portion  22 . The movement of the pull rod  6  towards the solenoid assembly  50  allows the pin guide  8  to also move towards the solenoid assembly  50 . At the same time, the release spring  2  biases the release pin  10  and bias spring retainer  11  away from the solenoid assembly  50  until the head portion  20  of the release pin  10  is in contact with the end of the bore. 
         [0039]    To reset the pin mechanism from an unreleased position to a released position, the pin mechanism needs to be manually reset. To reset the mechanism, the release spring  2  and release pin  10  must be compressed back to its initial position as shown in  FIG. 4 . By moving the release pin  10  to its initial position, the bias spring  9  and pull rod  6  are also moved back to the initial position shown in  FIG. 4 . While the release pin  10  is moving back to the initial position, the ball bearings  4  remain in place until they contact the ramped section  32  of the pull rod  6 . The ramped section  32  of the pull rod band the movement of the release pin  10  forces the ball bearings  4  up the ramp section  33  of the spring guide  3 , locking the ball bearings  4  back in place on the first outer diameter portion D 1  of the pull rod  6 . 
         [0040]    It should be noted that the force of the bias spring  9  within the bias spring retainer  11  aids the solenoid assembly  5  by providing a spring force through bias spring  9  that is in the same direction as movement of the armature  14  of the solenoid assembly  5 . This positive net force reduces the work the solenoid assembly  5  must perform. The additional force provided by the bias spring  9  also allows the force output from the solenoid to be reduced and thus the size of the solenoid can be significantly reduced. In other words, the bias spring  9  acts as a force equivalent of a counterbalance, where a small amount of force has a large impact. 
         [0041]    The pin mechanism of the present invention may be used in a fire extinguisher or other similar type device. The pin mechanism of the present invention may be used to rupture a diaphragm, as an emergency override, or deployment of an actuator. Alternatively, the pin mechanism may be used to lock a pin in place. 
         [0042]    The pin mechanism of the present invention provides numerous advantages over conventional pin mechanism designs. For example, the pin mechanism of the present invention has a fast solenoid response time of 4 milliseconds (ms) with the bias spring in comparison to a conventional design without a bias spring of 25 ms. A higher force output over long distances is also present within the present invention, with a force of 5 pounds force (lbf) needed in comparison to a conventional design without a bias spring of 30 lbf. The force of the mechanism of the present invention is 425 lbf of stored force, actuated with a solenoid output force of 5 lbf. Furthermore, the mechanism of the current invention has a stroke that ranges in excess of 0.500 inch (in). The power consumption of this embodiment of the present invention is approximately 120 watts, in comparison to 160 watts for a conventional design without a bias spring. In addition, the package size can be made as small as approximately 0.8 in diameter×0.8 in length. Therefore, the present invention provides a greater force over linger distance using a smaller package solenoid. 
         [0043]    The pin mechanism of the present invention outputs 3.7 Joules of energy. Other designs may provide 9-10 Joules of energy. 
         [0044]    Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.