Patent Publication Number: US-7721928-B2

Title: Nail-driving device with safety unit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority of Taiwanese Application No. 097112480, filed on Apr. 7, 2008. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a nail-driving device, and more particularly to a nail-driving device that includes a safety unit. 
   2. Description of the Related Art 
   Referring to  FIGS. 1 ,  2 , and  3 , a nil gun disclosed in U.S. Pat. No. 6,820,788 has a safety mechanism  6  for preventing misfires. The safety mechanism  6  includes an upper safety portion  601 , a lower safety portion  602 , and a cam member  503  connected between the upper and lower safety portions  601 ,  602  such that the upper and lower safety portions  601 ,  602  can be interconnected or disconnected from each other. To protect the cam member  603 , a shielding member  7  is provided to cover the same. However, during use, due to the presence of the shielding member  7 , it is difficult to register a nail  9  to be ejected with a hole  801  in a workpiece  8 . 
   SUMMARY OF THE INVENTION 
   The object of this invention is to provide a nail-driving device that includes a safety unit for preventing misfires and that can overcome the above-mentioned drawback associated with the prior art. 
   According to this invention, a nail-driving device comprising: 
   a body having a nail ejection portion extending along an axial direction; 
   a nail-striking member movable within the body along the axial direction; 
   an activation switch disposed on the body and having a contact portion, the activation switch being connected to the nail-striking member such that, when the contact portion is moved and thus retracted into the body, the activation switch activates the nail-striking member to move within the body; 
   a trigger unit including a trigger mechanism disposed pivotally on the body and adjacent to the activation switch, and a first resilient member disposed between the body and the trigger mechanism, the trigger mechanism being pivotable on the body between a non-firing position and a firing position, the first resilient member biasing the trigger mechanism toward the non-firing position; and 
   a safety unit including a safety mechanism movable within the nail ejection portion, a force-transmitting member mounted to the safety mechanism and adjacent to the trigger mechanism, and a second resilient member disposed between the body and the safety mechanism, the safety mechanism having a first distal end, and a second distal end opposite to the first distal end, the safety mechanism being movable relative to the nail ejection portion along the axial direction between a first position and a second position farther away from the nail ejection portion than the first position, the second resilient member biasing the safety mechanism toward the first position, the force-transmitting member having a connecting end disposed pivotally on the first distal end of the safety mechanism, and a driven end opposite to the connecting end and adjacent to the trigger mechanism, wherein: when the safety mechanism is limited in the first position, and when the trigger mechanism is pivoted to the firing position, the force-transmitting member moves the contact portion so that the contact portion is retracted into the body; and when movement of the safety mechanism between the first and second positions is allowed, and when the trigger mechanism is pivoted to the firing position, the force-transmitting member is driven by the trigger mechanism to move the safety mechanism from the first position to the second position such that the contact portion serves as a fulcrum. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of this invention will become apparent in the following detailed description of a preferred embodiment of this invention, with reference to the accompanying drawings, in which: 
       FIG. 1  is a side view of a conventional nail gun disclosed in U.S. Pat. No. 6,820,788; 
       FIG. 2  is a partly sectional side view of the conventional nail gun; 
       FIG. 3  is a fragmentary, schematic sectional view of the conventional nail gun in a state of use; 
       FIG. 4  is a perspective view of the preferred embodiment of a nail-driving device according to this invention when a trigger mechanism is disposed in a non-firing position and a safety mechanism is disposed in a first position; 
       FIG. 5  is a fragmentary schematic sectional side view of the preferred embodiment when the trigger mechanism is disposed in the non-firing position and the safety mechanism is disposed in the first position; 
       FIG. 6  is a fragmentary perspective view of a trigger unit and the safety mechanism; 
       FIG. 7  is a perspective view of the preferred embodiment when the trigger mechanism is disposed in a firing position and when the safety mechanism is limited in the first position; 
       FIG. 8  is a fragmentary schematic sectional side view of the preferred embodiment when the trigger mechanism is disposed in the firing position and when the safety mechanism is limited in the first position; 
       FIG. 9  is a perspective view of the preferred embodiment when the trigger mechanism is disposed in the firing position and when the safety mechanism is disposed in a second position; 
       FIG. 10  is a fragmentary schematic sectional side view of the preferred embodiment when the trigger mechanism is disposed in the firing position and the safety mechanism is disposed in the second position; 
       FIG. 11  is a fragmentary schematic sectional side view of the preferred embodiment when the trigger mechanism is disposed in the non-firing position and the safety mechanism is spaced apart from a locking member; 
       FIG. 12  is a fragmentary schematic sectional side view of the preferred embodiment when the trigger mechanism is pivoted from the non-firing position toward the firing position and a locking end of the locking member is pivoted toward a position-limiting portion of the safety mechanism; and 
       FIG. 13  is a view similar to  FIG. 12  but illustrating how the safety mechanism is moved to the first position by the locking member when the trigger mechanism reaches the firing position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 4 ,  5 , and  6 , the preferred embodiment of a nail-driving device  3  according to this invention includes a body  10 , a nail-striking member  20 , a magazine  30 , an activation switch  40 , a trigger unit  50 , and a safety unit  60 . 
   The body  10  has an accommodating portion  11 , a handle  12  connected to the accommodating portion  11 , a nail ejection portion  13  connected to the accommodating portion  11  and extending forwardly from the accommodating portion  11  along an axial direction (X), a first abutment portion  14  disposed at the nail ejection portion  13  and facing the accommodating portion  11 , and two guide pins  15  disposed rotatably on and above the nail ejection portion  13  and spaced apart from each other along the axial direction (X) The nail ejection portion  13  has a front end  131  and two side notches  132 . 
   The nail-striking member  20  is movable within the accommodating portion  11  along the axial direction (X), and extends into the nail ejection portion  13 . 
   The magazine  20  is connected between the nail ejection portion  13  and the handle  12  for receiving a plurality of nails  31 . 
   The activation switch  40  is disposed at a junction between the accommodating portion  11  and the handle  12  of the body  10 , and has a contact portion  41  extending forwardly along the axial direction (X). When the contact portion  41  is moved and retracted into the body  10 , the activation switch  40  activates the nail-striking member  20  to move forwardly along the axial direction (X) to thereby eject one of the nails  31  from the nail ejection portion  13 . 
   The trigger unit  50  includes a trigger mechanism  51  disposed pivotally on the junction of the accommodating portion  11  and the handle  12  and adjacent to the activation switch  40 , and a first resilient member  52  disposed between the accommodating portion  11  and the trigger mechanism  51 . 
   The trigger mechanism  51  includes a trigger member  53 , a locking member  54  disposed on the trigger member  53 , a positioning pin  55 , a retaining pin  56 , and a pivot pin  57 . 
   The trigger member  53  has an actuated end  531 , and a top end  532  opposite to the actuated end  531 . 
   The locking member  54  has a locking end  541 , and a mounting end  542  opposite to the locking end  541 . The locking end  541  has a stop end surface  543 , and a recess  544  formed in a bottom surface thereof and through the locking end  541  along the axial direction (X). 
   The positioning pin  55  extends through the top end  532  of the trigger member  53  and the mounting end  542  of the locking member  54 . The retaining pin  56  is disposed fixedly on the locking member  54  and between the locking end  541  and the mounting end  542 . The pivot pin  57  extends through the top end  532  of the trigger member  53 , the mounting end  542  of the locking member  54 , and is connected to the body  10 . 
   In this embodiment, the first resilient member  52  is configured as a torsion spring, and has a spring coil  521  sleeved on the positioning pin  55 , a first end foot  522  abutting against the accommodating portion  11 , and a second end foot  523  abutting against the retaining pin  45 . 
   The trigger mechanism  51  is pivotable on the body  10  about the pivot pin  57  between a non-firing position shown in  FIGS. 4 and 5  and a firing position shown in  FIGS. 7 and 8 . The first resilient member  52  biases the trigger mechanism  51  toward the non-firing position. 
   The safety unit  60  includes a safety mechanism  61  movable within the nail ejection portion  13  along the axial direction (X), a force-transmitting member  62  mounted to the safety mechanism  61  and adjacent to the trigger mechanism  51 , and a second resilient member  63  disposed between the body  10  and the safety mechanism  61 . 
   The safety mechanism  61  has a first safety member  64  and a second safety member  65  connected fixedly to and disposed in front of the first safety member  64 . 
   The first safety member  64  has a first distal end  641  adjacent to the trigger mechanism  51 , a first connecting end  542  opposite to the first distal end  641 , an intermediate section  643  extending between the first distal end  641  and the first connecting end  642  along the axial direction (X), and a position-limiting portion  644  disposed at the intermediate section  643 . The position-limiting portion  644  includes two spaced-apart symmetric position-limiting blocks  645 . Each of the position-limiting blocks  645  has a stop surface  646  facing the first distal end  641 , a first inclined surface  647  facing the first distal end  641 , and a second inclined surface  648  connected to the first inclined surface  647  and facing the first connecting end  642 . 
   The second safety member  65  is disposed movably on the nail ejection portion  13  of the body  10 , and extends between the nail ejection  13  and the guide pins  15 . The second safety member  65  has a second distal end  651  and a second connecting end  652  opposite to the second distal end  651  and connected fixedly to the first connecting end  642 , and a second abutment portion  63  located between the second distal end  651  and the second connecting end  652 . 
   The force-transmitting member  62  has a connecting end  621  disposed pivotally on said first distal end  641  of the safety member  64 , a driven end  622  opposite to the connecting end  621  and adjacent to the actuated end  531  of the trigger member  53 , and a force-transmitting section  623  extending between said connecting end  621  and the driven end  622  and in contact with the contact portion  41  of the activation switch  40 . 
   In this embodiment, the second resilient member  63  is configured as a compression spring, and has two ends abutting respectively against the first and second abutment portions  14 ,  653 . 
   The safety mechanism  61  is movable relative to the nail ejection portion  13  along the axial direction (X) between a first position shown in  FIGS. 4 and 5  and a second position shown in  FIGS. 9 and 10 . The second position is farther away from the nail ejection portion  13  than the first position. The second resilient member  63  biases the safety mechanism  61  toward the first position. When the safety mechanism  61  is disposed in the first position, the first distal end  641  of the first safety member  64  is adjacent to the activation switch  40 . When the safety mechanism  61  is moved from the first position toward the second position, the first distal end  641  is moved away from the activation switch  40 . 
   With reference to  FIGS. 7 and 8 , when it is desired to fix a workpiece  100  onto a wall  200 , a tip of one nail  31  projecting from the nail ejection portion  13  is registered with a hole  110  in the workpiece  100 , and the front end  131  of the nail ejection portion  13  and the second distal end  651  of the second safety member  65  are brought into contact with a surface  120  of the workpiece  100 . Because of contact between the second distal end  651  of the second safety member  65  with the workpiece  100 , the safety mechanism  61  is limited in the first position, and is not able to move relative to the body  10  along the axial direction (X). Afterwards, the actuated end  531  of the trigger member  53  is pressed to pivot the trigger mechanism  51  to the firing position. Hence, the force-transmitting section  623  of the force-transmitting member  62  moves the contact portion  41  so that the contact portion  41  is retracted into the body  10 . As a result, the activation switch  40  is activated to move the nail-striking member  20  to thereby eject the nail  31 . At the same time, the locking end  541  of the locking member  54  is moved to a position between the first connecting end  642  and the second inclined surfaces  648  of the position-limiting blocks  645  and adjacent to the second inclined surfaces  648 . 
   Conversely, with reference to  FIGS. 9 and 10 , when the front end  131  of the nail ejection portion  13  and the second distal end  651  of the second safety member  65  are not in contact with any workpiece, movement of the safety mechanism  61  relative to the body  10  is allowed, that is, the safety mechanism  61  is not limited in the first position. In this state, when the actuated end  531  of the trigger member  53  is pressed, the connecting end  621  of the force-transmitting member  62  is moved forwardly such that the contact portion  41  of the activation switch  40  serves as a fulcrum. Hence, the safety mechanism  61  is moved from the first position to the second position. In the second position, the second distal end  651  of the second safety member  62  is projected forwardly from the front end  131  of the nail ejection portion  13 , the second resilient member  63  is compressed, and the recess  544  of the locking end  541  of the locking member  54  engages the intermediate section  643  of the first safety member  64 . Further, the locking end  541  of the locking member  54  is disposed between the first distal end  641  of the first safety member  64  and the stop surfaces  646  of the position-limiting blocks  645  and adjacent to the stop surfaces  646 . As such, if the second distal end  651  of the second safety member  65  is pushed unintentionally and rearwardly, the stop surfaces  646  of the position-limiting blocks  645  come into contact with the stop end surfaces  543  of the locking end  541  of the locking member  54 , thereby preventing the safety mechanism  61  from moving rearwardly to the first position. Thus, as long as the front end  131  of the nail ejection portion  13  and the second distal end  651  of the second safety member  65  are not in contact with any workpiece, misfires can be prevented. 
   The nail-driving device of this invention has the following advantages:
         (1) When the driving device is not pressed against the workpiece  100 , and when the actuated end  531  of the trigger member  53  is pressed, the locking end  541  of the locking member  54  can obstruct rearward movement of the position-limiting portion  644  of the first safety member  64  to thereby prevent misfires. Due to the design of the locking member  54 , there is no need to provide a separating mechanism, such as the cam member  603  (see  FIG. 3 ) of the above-mentioned prior art, for interconnecting the first and second safety members  64 ,  65 . Thus, the first and second safety members  64 ,  65  can be interconnected fixedly. As a result, the cover  7  (see  FIGS. 1 and 2 ) required for protecting the cam member  603  (see  FIG. 3 ) of the above-mentioned prior art can be omitted to allow the nail  31  projecting from the nail ejection portion  13  to be easily register with the hole  110  in the workpiece  100 .   (2) Referring to  FIG. 11 , in a situation where the workpiece  100  is thin such that, after the tip of the nail  31  projecting from the nail ejection portion  13  is passed through the hole  101  in the workpiece  100  to contact the wall  120 , the second distal end  651  of the second safety member  65  is spaced apart from the workpiece  100 , when the actuated end  531  of the trigger member  53  is pressed, the force-transmitting member  62  is driven by the trigger member  53  to move the safety mechanism  61  forwardly from the first position such that the contact portion  41  of the activation switch  40  serves as the fulcrum. During forward movement of the safety mechanism  61  from the first position, the locking end  541  of the locking member  54  is pivoted toward the position-limiting blocks  645 , as shown in  FIG. 12 , to a position between the first connecting end  642  of the first safety member  64  and the position-limiting blocks  645  and adjacent to the position-limiting blocks  645 . Subsequently, the locking member  54  moves the safety mechanism  61  back to the first position, as shown in  FIG. 13 . At this time, since the safety mechanism  61  is disposed in the first position, the force-transmitting member  62  can pivot about the first distal end  641  of the first safety member  54  to move the contact portion  41  to thereby activate the activation switch  40 .       

   With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated by the appended claims.