Patent Publication Number: US-7913889-B2

Title: Automatic quick clear nose for nailer

Description:
TECHNICAL FIELD 
     This technology relates to a tool for driving fasteners such as nails or staples. 
     BACKGROUND 
     A pneumatic tool for driving fasteners has a piston/cylinder assembly with a driver blade. The tool further has a nose configured as a barrel through which the driver blade drives the fasteners. A fastener may sometimes become jammed in the nose. 
     SUMMARY OF THE INVENTION 
     A fastener driving apparatus includes a motor with an output shaft. The motor is shiftable between a de-energized condition in which it can not be actuated to move the output shaft, and an energized condition in which it can be actuated to move the output shaft. The apparatus further includes a nose and a control device. The nose is shiftable between differently configured conditions, including a first condition for guiding a fastener driven by the output shaft, and a second condition for releasing a fastener that jams when the nose is in the first condition. The control device maintains the nose in the first condition whenever the motor is in the energized condition. 
     In a preferred embodiment, the control device shifts the nose to the first condition when the motor is shifted to the energized condition, and shifts the nose back to the second condition when the motor is shifted to the de-energized condition. The motor in the preferred embodiment is a pneumatic motor which is energized by elevated pneumatic pressure. The control device in the preferred embodiment holds the nose in the first condition under the force of elevated pneumatic pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of a nailer. 
         FIG. 2  is a view of parts of the nailer of  FIG. 1 . 
         FIG. 3  is a view taken on line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a view taken on line  4 - 4  of  FIG. 2 . 
         FIG. 5  is a view similar to  FIG. 2 , showing parts in different positions. 
         FIG. 6  is a view similar to  FIG. 3 , showing additional parts of the nailer. 
         FIG. 7  is a view similar to  FIG. 6 , showing parts in different positions. 
     
    
    
     DETAILED DESCRIPTION 
     The structures shown schematically in the drawings have parts that are examples of the elements recited in the claims. The illustrated structures thus include examples of how a person of ordinary skill in the art can make and use the claimed invention. They are described here to meet the enablement and best mode requirements of the patent statute without imposing limitations that are not recited in the claims. 
     The tool  10  shown in  FIG. 1  is an example of a tool equipped with the claimed invention. This particular tool  10  is a nailer with a nail magazine  12 . The nailer  10  has a housing  14  containing a motor in the form of a pneumatic piston/cylinder assembly  16 . The piston/cylinder assembly  16  has an output shaft in the form of a driving blade  18 . A nose  20  projects forward from the housing  14 , and has an open end  22 . The nailer  10  further has a trigger assembly  24  for actuating the piston/cylinder assembly  16 . When the piston/cylinder assembly  16  is actuated, it advances the driving blade  18  through the nose  20  to drive a nail from the magazine  12  outward through the open end  22 . 
     As shown in  FIGS. 2 and 3 , the nose  20  includes a cylindrical tube  30  centered on a driving axis  33 . The tube  30  has a pair of opposed, circumferentially spaced-apart edge surfaces  36 . The edge surfaces  36  extend along the tube  30  in directions parallel to the driving axis  33 , and thus define opposite sides of a slot  37  that also extends along the tube  30  parallel to the driving axis  33 . The slot  37  extends along the length of the nose  20  past the magazine  12  and onward to the open end  22  ( FIG. 1 ). 
     As further shown in  FIG. 2 , the nails  40  in this particular example have circular heads  42  on cylindrical shanks  44 . A pair of parallel, frangible plastic strips  48 , one of which is shown in  FIG. 2 , engage the nails  40  at the shanks  44 . The plastic strips  48  collate the nails  40  in a row such that each head  42  partially overlaps an adjacent head  42  in the row. The magazine  12  is spring-loaded to advance the nails  40  transversely into the nose  20  through the slot  37 . 
     The driving blade  18  extends into the nose  20  as shown in  FIG. 2 , and is shaped as shown in  FIG. 3 . A recessed arcuate edge surface  50  of the driving blade  18  extends along its length. The edge surface  50  defines a groove  53  that interrupts an otherwise cylindrical shape centered on the driving axis  33 . The groove  53  in the driving blade  18  is aligned beside the slot  37  in the nose  20 . 
     When the piston/cylinder assembly  16  advances the driving blade  18  along the axis  33 , it moves the driving blade  18  toward and against the head  42  of the nail  40  to be driven, as shown in  FIGS. 2 and 5 . The groove  53  provides clearance for the driving blade  18  to move axially past the collated head  42  of the next nail  40 , which has then been advanced partly from the magazine  12  into the nose  20  through the slot  37 . Further movement of the driving blade  18  forces the head  42  of the driven nail  40  to sever the plastic collating strips  48  and move fully through and outward from the nose  20 . The return stroke of the piston/cylinder assembly  16  retracts the driving blade  18  sufficiently for the magazine  12  to advance the next nail  40  into the nose  20  through the slot  37 . 
     It is possible for a nail  40  to become jammed in the nose  20 . For this reason the nose  20  is configured as a mechanism that is shiftable between first and second conditions. When in the first condition, the nose  20  is configured to guide a nail  40  along the driving axis  33  and outward from the open end  22  under the influence of the driving blade  18 . When in the second condition, the nose  20  is configured to release a nail that jams when the nose  20  is in the first condition. 
     In the preferred embodiment, the nose  20  includes a door  70  ( FIGS. 6 and 7 ). When the door  70  is in the closed position shown in  FIG. 6 , the nose  20  is in the first condition for guiding a nail  40  along the driving axis  33 . When the door  70  is in the open position shown in  FIG. 7 , the nose  20  is in the second condition for releasing a jammed nail  40 . 
     In this particular example, the door  70  is a separate arcuate section of the slotted cylindrical tube  30 . The door  70  and another arcuate section  72  fit together to form the circular cross-section of the tube  30 . Specifically, the door  70  includes one of the edge surfaces  36  beside the slot  37 , and has an inner edge surface  74  remote from the slot  37 . In the closed position of  FIG. 6 , the inner edge surface  74  of the door  70  abuts, or is located closely adjacent to, an opposed edge surface  76  of the other section  72  of the tube  30 . The closed door  70  is thus included in the configuration of the nose  20  that closely surrounds a nail head  42  to guide the nail  40  along the driving axis  33 . 
     In the open position of  FIG. 7 , the door  70  is spaced from the other section of the  72  of the tube  30 . This enlarges the cross-sectional area surrounded by the two sections  70  and  72  of the tube  30 , and also enlarges the slot  37 . Those dimensions of the nose  20  are enlarged sufficiently to provide clearance for a jammed nail  40  to fall or be removed manually from the tube  30  either axially outward through the open end  22  or transversely outward through the slot  37 . 
     As further shown in  FIGS. 6 and 7 , the nailer  10  is equipped with a control device to shift the nose  20  between the first and second conditions. The preferred embodiment of the control device is a single acting pneumatic piston/cylinder assembly  80  including a piston  82 , a cylinder  84 , and an output shaft  86 . The cylinder  84  has a variable volume pneumatic pressure chamber  87  with a port  89  on one side of the piston  82 , and has a chamber  91  with a vent  93  on the other side of the piston  82 . A spring  94  in the vented chamber  91  acts directly on the piston  82  to bias the piston  82  toward the pressure chamber  87 . The output shaft  86  is linked to the door  70 . 
     Referring again to  FIG. 1 , the nailer  10  includes a pneumatic coupling  96 . As shown schematically in  FIGS. 1 ,  6  and  7 , the nailer coupling  96  connects to a source coupling  98  on a pneumatic pressure line  100  that extends from a compressor  102  or other source of elevated pneumatic pressure for powering the piston/cylinder assembly  16 . The nailer  10  further includes a pneumatic working pressure line  106  communicating the nailer coupling  96  with the piston/cylinder assembly  16 , and a pneumatic control pressure line  108  communicating the nailer coupling  96  with the cylinder  84  in parallel with the piston/cylinder assembly  16 . A pressure regulator  110  may be included to reduce the pressure transmitted to the cylinder  84 . 
     In operation of the nailer  10 , the user connects the nailer coupling  96  to the source coupling  98  to transmit elevated pneumatic pressure to the piston/cylinder assembly  16  through the working pressure line  106 . The control pressure line  108  simultaneously transmits elevated pneumatic pressure from the nailer coupling  96  to the cylinder  84 . This pressurizes the pressure chamber  87  to move the piston  82  in a forward stroke, which is from left to right as viewed in  FIG. 6 , against the bias of the spring  94 . The output shaft  86  then moves the door  70  to the closed position, and continues to hold the door  70  in the closed position as long as the pressure chamber  87  remains pressurized to hold the piston  82  in the position of  FIG. 6 . The nose  20  will thus remain in the first condition for ejecting driven nails  40  as long as the nailer coupling  96  continues to receive elevated pneumatic pressure from the source  102 . This ensures that the door  70  will be in the closed position whenever the piston/cylinder assembly  16  is energized with elevated pneumatic pressure from the source  102 , and thus provides a safety feature by ensuring that the door  70  will be in the closed position whenever the user actuates the piston/cylinder assembly  16  to advance the driving blade  18  through the nose  20 . 
     If a nail  40  becomes jammed in the nose  20 , the user can shift the nose  20  from the first condition to the second condition by turning off the compressor  102  and bleeding the air from the line  100  or by disconnecting the nailer coupling  96  from the source coupling  98 . The pressure chamber  87  then returns to atmospheric pressure by venting through the port  89  to the control pressure line  108 . As the pressure chamber  87  vents, the spring  94  moves the piston  82  through a return stroke in which the output shaft  86  moves the door  70  to the open position. This frees a jammed nail, and provides an additional safety feature by ensuring that the piston/cylinder assembly  16  is de-energized whenever the door  70  is open for a user to manually remove a jammed nail  40 . 
     This written description sets forth the best mode of carrying out the invention, and describes the invention so as to enable a person skilled in the art to make and use the invention, by presenting examples of elements recited in the claims. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples, which may be available either before or after the application filing date, are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they have equivalent structural elements with insubstantial differences from the literal language of the claims.