Patent Publication Number: US-10759033-B2

Title: Fastener driving tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Patent Application No. 107103776, filed on Feb. 2, 2018. 
     FIELD 
     The disclosure relates to a hand-held fastener driving tool, and more particularly to a fastener driving tool using a torsion spring unit for urging a fastener. 
     BACKGROUND 
     Referring to  FIGS. 1 and 2 , a conventional spring actuated fastener driving tool  1  as disclosed in Taiwanese Patent Publication No. 545350 includes a housing  11 , a nail striking unit  12  and a handle unit  13 . The housing  11  has a central shaft  111 . The nail striking unit  12  has a striking member  121  mounted in a front portion of the housing  11  for reciprocal movement in an upper-and-lower direction, and a leaf-spring  122  disposed in the housing  11  and connected at a front end to the striking member  121 . The handle unit  13  has a handle  131  pivotably mounted to the central shaft  111 , and a compressible spring  132  disposed in the housing  11  to be compressed to produce a biasing force to the handle  131 . The handle  131  is engageable with the striking member  121  at a front end thereof. 
     When the handle  131  is pivoted about the central shaft  111  by a manual press force applied on a rear end thereof to move the striking member  121  upwardly, the leaf-spring  122  is resiliently deflected and loaded. Then, a successive pivot movement of the handle  131  results in disengagement thereof from the striking member  121 , and at this moment the leaf spring  122  is thus freed to resiliently return the striking member  121  downwardly to eject a fastener. 
     However, during pivot movement of the handle  131 , the leaf-spring  122  must be resiliently deflected by a relatively long distance to accumulate a sufficient biasing energy. Thus, a large operating effort is required to move the striking member  121  for the long distance to bend the leaf-spring  122  to a sufficient degree. 
     SUMMARY 
     Therefore, an object of the disclosure is to provide a fastener driving tool which has a simple construction that is operable with less effort. 
     According to the disclosure, a fastener driving tool includes a housing, a striking member, an energy storing unit and a handle unit. The housing has two housing halves which are matingly engaged with each other to define a housing space, a pivot axle which is disposed in the housing space, and a fastener striking opening at a bottom of a forward end of the housing. The striking member is mounted in the housing for reciprocal movement in an up-and-down direction. The striking member has a lower striking end which faces the fastener striking opening, and an upper driven end which is formed with an engaged slot. The energy storing unit is disposed in the housing space, and includes an energy storing assembly which has at least one torsion spring that is twistable about a fixed axle disposed rearwardly of the pivot axle. The torsion spring has a short leg and a long leg which extend tangentially and forwardly. The long leg extends beyond the short leg to engage with the striking member. The energy storing unit further includes a return spring which is disposed downwardly of the short leg to be compressed by the short leg to store a return energy. The handle unit includes a handle having a front pivot end which is pivotably mounted in the housing space and on the pivot axle, a rear effort end which is opposite to the front pivot end, and a forcing portion which is interposed between the front pivot end and the rear effort end and which is disposed to force the short leg to move downwardly when the rear effort end is turned about the pivot axle. The handle unit further includes an anchoring member which is slidably mounted to the front pivot end of the handle and which has a forward anchoring portion that projects forwardly of the front pivot end to be engaged in the engaged slot of the striking member, and a biasing member which is disposed to bias the anchoring member forwardly. The handle is pivotally movable relative to the pivot axle from a ready position, where the lower striking end of the striking member is in close proximity to the fastening striking opening, and the forward anchoring portion of the anchoring member is engaged in the engaged slot, through an intermediate position, where, via an abutting engagement of the forcing portion with the short leg, the short leg is moved downwardly to compress the return spring to generate the return energy, and where the anchoring member is moved with the handle for being brought upwardly and rearwardly to engagingly move the striking member and the long leg of the torsion spring upwardly to gradually increase a loading of the torsion spring for the striking member, to a striking position, where the anchoring member is disengaged from the engaged slot of the striking member, and the torsion spring is freed to release a biasing energy to move the striking member downward toward the fastener striking opening. During a pivotal movement of the handle from the striking position to the ready position, the return spring is freed to release the return energy to urge the energy storing assembly upwardly and to cause the pivot movement of the handle and the anchoring member about the pivot axle and an upward movement of the long leg and the striking member to make a sliding engagement of the striking member with the forward anchoring portion of the anchoring member in the up-and-down direction, while the biasing member is loaded to accumulate a biasing force that urges the anchoring member to be engaged in the engaged slot. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a schematic partly-sectioned view of a conventional spring actuated fastener driving tool; 
         FIG. 2  is a schematic partly-sectioned view of the conventional fastener driving tool illustrating a state where a handle is pressed; 
         FIG. 3  is a perspective view illustrating an embodiment of a fastener driving tool according to the disclosure; 
         FIG. 4  is an exploded perspective view illustrating a portion of the embodiment; 
         FIG. 5  is a close-up exploded perspective view illustrating a handle unit of the embodiment; 
         FIG. 6  is a schematic side view of the embodiment, wherein a housing half of the embodiment is removed for the sake of clarity, and wherein a state where a handle of the handle unit is in a ready position is illustrated; 
         FIG. 7  is a perspective view of a striking member and an energy storing unit of the embodiment; 
         FIG. 8  is a perspective view similar to  FIG. 7 , but taken from another angle; 
         FIG. 9  is a fragmentary, schematic side view of the embodiment, illustrating a state where the handle is in the ready position; 
         FIG. 10  is a schematic side view of the embodiment, illustrating a state where the handle is in a striking position; 
         FIGS. 11 to 16  are perspective views of the embodiment, wherein a housing half of the embodiment is removed, and wherein the fastener driving tool during various phases of a fastener driving cycle is illustrated; 
         FIG. 17  is a view similar to  FIG. 9 , illustrating a state where the handle is returned from the striking position to the ready position; 
         FIG. 18  is a perspective view illustrating another embodiment of the fastener driving tool according to the disclosure, a housing half being removed for the sake of clarity; 
         FIG. 19  is a perspective view of a handle unit and an energy storing unit of the embodiment shown in  FIG. 18 ; and 
         FIG. 20  is a perspective view similar to  FIG. 18 , illustrating a state where a handle of the handle unit is pressed to a striking position. 
     
    
    
     DETAILED DESCRIPTION 
     Before the disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics. In the following description, the directions, such as “front-and-rear direction (X)”, “left-and-right direction (Y)” and “up-and-down direction (Z)”, indicate the orientations of the embodiment in use. 
     Referring to  FIGS. 3 and 4 , an embodiment of a fastener driving tool according to the disclosure is shown to include a housing unit  2 , a striking member  3 , an energy storing unit  4  and a handle unit  5 . 
     With reference to  FIGS. 4 to 8 , the housing  2  has two housing halves  21 ,  22  which are matingly engaged with each other to define a housing space, a pivot axle  23  which is disposed in the housing space and extends in a left-and-right direction (Y), a fixed axle  24  which is detachably disposed in the housing space and located rearwardly and downwardly of and parallel to the pivot axle  23 , a spring bracket  25  which is disposed in the housing space adjacent to a forward end of the housing halves  21 ,  22 , a stop  26  which is disposed on and extends forwardly of the spring bracket  25 , a guiding member  27  which is disposed in a lower and forward end of the housing space to define a striking track  271  in an up-and-down direction (Z), and a fastener striking opening  28  which is located at a bottom of a forward end of the housing  2  and formed at a lowermost end of the striking track  271 . 
     The striking member  3  is mounted in the housing space for reciprocal movement along the striking track  271 . The striking member  3  includes an elongated plate body  31  having a lower striking end  313  which faces the fastener striking opening  28 , and an upper driven end  314  which extends upwardly of the lower striking end  313  and which is formed with an engaged slot  311  and a connected slot  312  below the engaged slot  311 . The striking member  3  further includes a sliding member  32  extending upwardly from and deflected forwardly of the upper driven end  314 . 
     The energy storing unit  4  is disposed in the housing space, and includes an energy storing assembly  41  and a return spring  42 . The energy storing assembly  41  has two torsion springs  411  which respectively have coils  413  sleeved around the fixed axle  24  to be twistable about the fixed axle  24  and arranged in the left-and-right direction (Y), and each of which has a short leg  414  and a long leg  415  that extend tangentially and forwardly from the respective coil  413  in a front-and-rear direction (X). The long leg  415  extends forwardly beyond the short leg  414  to be engaged in the connected slot  312  of the striking member  3 . 
     The energy storing assembly  41  further has an adaptor  412  fixedly connected to the short legs  414  of the torsion springs  411 . The adaptor  412  has a base wall  416  which is disposed under the torsion springs  411  and on an upper major surface of which the short legs  414  of the torsion springs  411  are placed, two side walls  417  which extend upwardly from a periphery of the base wall  416  to terminate at upwardly facing edges  410  and which are spaced apart from each other in the left-and-right direction (Y), two retaining protrusions  4171  which extend inwardly toward each other from front ends of the side walls  417 , respectively, to cooperate with the base wall  416  to retain the short legs  414  therebetween, two stabilizing portions  418  which extend upwardly from the periphery of the base wall  416  and which are spaced apart from each other in the left-and-right direction (Y) and rearwardly of the side walls  417 , and a lower protrusion  419  which extends downwardly from the base wall  416  and on which an end of the return spring  42  is connected. The stabilizing portions  418  are configured to firmly retain middle sections of the short legs  414  of the torsion springs  411 . In this embodiment, the adaptor  412  is formed from a metal material as an integral single piece to have the side walls  417 , the stabilizing portions  418  and the lower protrusion  419  bent from the base wall  416 . In assembly, the coils  413  of the torsion springs  411  are firstly sleeved around the fixed axle  24 . The adaptor  412  is then attached to the torsion springs  411 . Next, the fixed axle  24  is mounted to the housing halves  21 ,  22  with the retaining protrusions  4171  and the stabilizing portions  418  abutting against the front and middle sections of the short legs  414  of the torsion springs  411  so as to firmly retain the short legs  414  to the adaptor  412 . In modified examples, the adaptor  412  may have only the stabilizing portions  418  or the retaining protrusions  4171  disposed to retain the short legs  414  of the torsion springs  411 . 
     The return spring  42  is held on the spring bracket  25  and has the end connected to the lower protrusion  419  of the adaptor  412  to be compressed by the short legs  414  of the torsion springs  411  to store a return energy in the up-and-down direction. In this embodiment, the return spring  42  is in the form of a truncated conical compression spring. 
     With reference to  FIGS. 4 to 6  and  FIG. 9 , the handle unit  5  includes a handle  51 , an anchoring member  52 , a biasing member  53  and a handle sleeve  54 . The handle  51  has a front pivot end  514  which is pivotably mounted in the housing space and on the pivot axle  23 , a rear effort end  515  which is opposite to the front pivot end  514  in the front-and-rear direction (X), and a forcing portion  513  which is interposed between the front pivot end  514  and the rear effort end  515  and which is disposed to force the short legs  414  of the torsion springs  411  to move downwardly when the rear effort end  515  is pivoted about the pivot axle  23 . Specifically, the handle  51  has an elongated upper wall  511  formed with an elongated slot  510  which extends in the front-and-rear direction (X), two side major walls  512  extending downwardly from the upper wall  511  and spaced apart from each other in the left-and-right direction (Y) so as to define an elongated sliding space therebetween, and an upper connecting member  517  disposed on the upper wall  511 . Each of the side major walls  512  has a pivot hole  516  which is formed at a front end thereof to serve as the front pivot end  514  to be sleeved around the pivot axle  23 , and a holding protrusion  518  which is disposed rearwardly of the pivot hole  516  and protrudes laterally toward the other one of the side major walls  512 . The forcing portion  513  is disposed on each of the side major walls  512  and projects in the left-and-right direction (Y) so as to abut against the upwardly facing edges  410  of the side walls  417  of the adaptor  412  in the up-and-down direction (Z). In this embodiment, the handle  51  is made from a metal plate bent to have the upper wall  511  and the side major walls  512  that project forwardly beyond the upper wall  511  to form the front pivot end  514 . 
     The anchoring member  52  is slidably mounted to the front pivot end  514  of the handle  51  and in the sliding space, and has a forward anchoring portion  524  which projects forwardly of the front pivot end  514  of the handle  51  to be engaged in the engaged slot  311  of the striking member  3 , a sliding guide  526  which is received in and slidable along the elongated slot  510  and which has a tip end that projects upwardly of the elongated slot  510  to be opposite to the upper connecting member  517 , a forwardly-opened front notched portion  525  which is rotatably sleeved around the pivot axle  23 , and a rear abutment portion  527  which is disposed to abut against the holding protrusions  518  of the handle  51 . In this embodiment, the anchoring member  52  is formed as a one single piece, and includes a top wall  521  having the forward anchoring portion  524  and the sliding guide  526  at front and rear ends thereof, respectively, and two lateral walls  522  extending downwardly from the top wall  521  and having the front notched portion  525  and the rear abutment portion  527  at front and rear ends thereof, respectively. The biasing member  53  is a compression spring and has two ends  532 ,  533  which are respectively engaged with the sliding guide  526  and the upper connecting member  517  so as to bias the anchoring member  52  forwardly relative to the handle  51 . The handle sleeve  54  is mounted on the handle  51  to cover the rear effort end  515  for offering a comfortable press operation. 
     With reference to  FIGS. 6 and 10 , the handle  51  is pivotally movable relative to the pivot axle  23  between a ready position (see  FIG. 6 ) and a striking position (see  FIG. 10 ). In use, the rear effort end  515  of the handle  51  is pressed downward to pivot the handle  51  from the ready position toward the striking position. 
     Referring to  FIGS. 6 and 11 , when the handle  51  is in the ready position, the lower striking end  313  of the striking member  3  is in close proximity to the fastening striking opening  28  and the forward anchoring portion  524  of the anchoring member  52  is engaged in the engaged slot  311  of the striking member  3 . 
     Referring to  FIG. 12 , during the pivotal movement of the handle  51  from the ready position toward the striking position (i.e., through an intermediate position), via an abutting engagement of the forcing portion  513  with the adaptor  412  and via the short legs  414  of the torsion springs  411  in turn, the adaptor  412  and the short legs  414  are moved downwardly to compress the return spring  42  to generate the return energy, while the anchoring member  52  is moved with the handle  51  for being brought upwardly and rearwardly to engagingly move the striking member  3  and the long legs  415  of the torsion springs  411  upwardly to gradually increase a loading of the torsion springs  411  for the striking member  3 . 
     As shown in  FIG. 13 , once the handle  51  approaches closely to the striking position, the forward anchoring portion  524  of the anchoring member  52  is able to be disengaged from the engaged slot  311  of the striking member  3 . Next, in the state as shown in  FIG. 14 , the anchoring member  52  is being disengaged from the engaged slot  311  of the striking member  3  while the torsion springs  411  remain unmoved. Subsequently, referring to  FIGS. 10 and 15 , in the striking position, the anchoring member  52  is disengaged from the engaged slot  311  of the striking member  3  while the torsion springs  411  are freed to release a biasing energy to move the striking member  3  downward toward the fastener striking opening  28  by the long legs  415  for performing a fastener striking stroke. At this stage, the downward movement of the long legs  415  is stopped by the stop  26 . 
     Then, referring to  FIGS. 16 and 17 , the handle  51  is released from the user, and is returned to the ready position by means of the return spring  42 . During a pivotal movement of the handle  51  from the striking position to the ready position, the return spring  42  is freed to release the return energy to urge the energy storing assembly  41  upwardly and to pivot the rear effort end  515  of the handle  51  upwardly and about the pivot axle  23 . Meanwhile, the anchoring member  52  is pivotally moved downwardly and about the pivot axle  23 . Also, an upward movement of the long legs  415  and the striking member  3  occurs to make a sliding engagement of the striking member  3  with the forward anchoring portion  524  of the anchoring member  52  in the up-and-down direction (Z), while the biasing member  53  is loaded to accumulate a biasing force that urges the anchoring member  52  to be engaged in the engaged slot  311 . The sliding member  32  is configured to facilitate the slidable engagement with the forward anchoring portion  524  of the anchoring member  52  to render the pivot movement of the anchoring member  52  about the pivot axle  23  back to the ready position smooth and successful, which in turn loads the biasing member  53 . In other words, upon a sliding movement of the forward anchoring portion  524  on the sliding portion  32  of the striking member  3  when the handle  51  is pivotally moved from the striking position to the ready position, the anchoring member  52  is moved rearwardly relative to the handle  51  to compress the biasing member  53  for storing the biasing force. 
     Referring to  FIGS. 18 and 19 , in another embodiment, the energy storing assembly  41  has one torsion spring  411  and the adaptor  412 . The torsion spring  411  has a coil  413  sleeved around the fixed axle  24 , a short leg  414  extending tangentially and forwardly from the coil  413 , and further downwardly and in turn rightwardly, and a long leg  415  extending tangentially and forwardly from the coil  413  and beyond the short leg  414  to be engaged in the connected slot  312  of the striking member  3 . The adaptor  412  has an upwardly opened retaining slot  4121  in which a rightwardly extending section of the short leg  414  is retained, and a lower protrusion  419  disposed opposite to the retaining slot  4121  to be connected with an end of the return spring  42 . Also, the forcing portion  513  of the handle  51  abuts against the short leg  414 . As shown in  FIGS. 18 and 20 , the handle  51  is pivotable about the pivot axle  23  between the ready position (see  FIG. 18 ) and the striking position (see  FIG. 20 ). 
     As illustrated, in the disclosure, with the torsion spring(s)  411  having the short and long legs  414 ,  415  movable in opposite directions to cause a higher degree of twist, a greater energy can be stored in the torsion spring(s)  411  during the pivotal movement of the handle  51  from the ready position to the striking position, and hence the striking member  3  can be moved upwardly in a less distance during the fastener driving cycle, which renders the operation of the handle  51  effortless. With two of the torsion springs  411  arranged in the left-and-right direction, an even stored biasing energy is produced to move the striking member  3  smoothly and successfully. Moreover, with the retaining protrusions  4171  and the stabilizing portions  418  abutting against the front and middle sections of the short legs  414  of the torsion springs  411 , the short legs  414  of the torsion springs  411  are firmly retained to the adaptor  412  and the entire structure of the energy storing assembly  41  is strengthened. 
     While the disclosure has been described in connection with what are considered the exemplary embodiments, it is understood that this disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.