Patent Publication Number: US-2018050396-A1

Title: Trigger Assembly for a Pneumatic Tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Patent Application No. 105126708, filed on Aug. 22, 2016. 
     FIELD 
     The disclosure relates to a trigger assembly, and more particularly to a trigger assembly for a pneumatic tool. 
     BACKGROUND 
     Referring to  FIG. 1 , a conventional pneumatic tool disclosed in Taiwanese Patent No. 1370046 includes a main body  11 , a valve member  12  that is movably mounted to the main body  11  and that controls airflow in the main body  11  for firing a nail, a safety member  13  that is movably mounted to the main body  11 , a trigger member  14  that is pivoted to the main body  11 , a lever member  15  that is pivoted to the safety member  13  and that is located between the valve member  12  and the trigger member  14 , and a latch member  16  that is co-movably mounted to the trigger member  14  and that is moved onto the path of movement of the safety member  13  upon depression of the trigger member  14 . 
     When a front end of the safety member  13  is pushed against an object, the lever member  15  is rotated by the trigger member  14 , upon the depression of the trigger member  14 , to depress the valve member  12  so as to fire the nail. When the trigger member  14  is continuously depressed after the firing of the nail, the latch member  16  remains located on the path of movement of the safety member  13  to limit the movement of the safety member  13 . As such, the valve member  12  cannot move back to its original position, and the conventional pneumatic tool is prevented from firing another nail without release of the trigger member  14 . 
     By virtue of the latch member  16 , the conventional pneumatic tool is permitted to fire a nail only by sequentially pushing the safety member  13  against an object and depressing the trigger member  14  (i.e., a sequential firing mode), and is only permitted to fire another nail after the release of trigger member  14 . However, the conventional pneumatic tool cannot be operated in a repetitive firing mode, in which the trigger member  14  is continuously depressed and the safety member  13  is repeatedly pushed against an object/objects to repeatedly fire nails. 
     SUMMARY 
     Therefore, an object of the disclosure is to provide a trigger assembly that can alleviate the drawback of the prior art. 
     According to one aspect of the disclosure, the trigger assembly is for use in a pneumatic tool. The pneumatic tool includes a casing, a valve rod that is movably mounted to the casing and that is operable to control airflow in the pneumatic tool for firing a nail, and a safety member that is movably mounted to the casing The safety member is movable relative to the casing between a first position where the safety member is proximate to a valve seat to which the valve rod is mounted, and a second position where the safety member is distal from the valve seat. The trigger assembly includes a trigger unit, a lever member and a switch unit. The trigger unit includes a trigger that is pivoted to the casing. The trigger is pivotable relative to the casing between a released position and a depressed position. The lever member is pivoted to the safety member and is partially located between the valve rod and the trigger for depressing the valve rod. The switch unit includes a latch member that is pivoted to the casing and that is pivotable relative to the trigger, and a switch member that is rotatably mounted to the casing and that is rotatable between a sequential firing position where the switch member is separated from the path of movement of the latch member, and a repetitive firing position where the switch member is disposed on the path of movement of the latch member. When the trigger is depressed without pushing the safety member against an object, the lever member is driven by the trigger to move the safety member from the first position to the second position so as to prevent firing of the nail. When the switch member is at the sequential firing position and when the trigger is depressed after the safety member is pushed against an object to be maintained at the first position, the lever member is driven by the trigger to depress the valve rod so as to fire the nail, and the latch member is permitted to move onto the path of movement of the safety member upon the depression of the trigger, such that when the safety member pushes the latch member and moves past the latch member to the second position after the firing of the nail, the latch member hinders the movement of the safety member toward the first position so as to prevent firing of another nail When the switch member is at the repetitive firing position and when the trigger is continuously depressed, the latch member is prevented from moving onto the path of movement of the safety member, and the safety member can be repeatedly pushed against the object to move from the second position to the first position so as to repeatedly fire nails. 
     According to another aspect of the disclosure, the trigger assembly is for use in a pneumatic tool. The pneumatic tool includes a casing, a valve rod that is movably mounted to the casing and that is operable to control airflow in the pneumatic tool for firing a nail, and a safety member that is movably mounted to the casing. The safety member is movable relative to the casing between a first position where the safety member is proximate to a valve seat to which the valve rod is mounted, and a second position where the safety member is distal from the valve seat. The trigger assembly includes a trigger unit, a lever member and a switch unit. The trigger unit includes a trigger that is pivoted to the casing. The trigger is pivotable relative to the casing between a released position and a depressed position. The lever member is pivoted to the safety member and is partially located between the valve rod and the trigger for depressing the valve rod. The switch unit includes a latch member that is pivoted to the casing and that is pivotable relative to the trigger, and a switch member that is rotatably mounted to the casing and that is rotatable between a sequential firing position where the switch member is separated from the path of movement of the latch member to permit the latch member to be moved onto the path of movement of the safety member upon depression of the trigger, and a repetitive firing position where the switch member is disposed on the path of movement of the latch member so as to prevent the latch member from being moved onto the path of movement of the safety member. 
    
    
     
       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 fragmentary sectional view illustrating a conventional pneumatic tool in Taiwanese Patent No. I370046; 
         FIG. 2  is a perspective view illustrating a pneumatic tool with an embodiment of the trigger assembly according to the disclosure; 
         FIG. 3  is an exploded perspective view illustrating the embodiment; 
         FIG. 4  is a perspective view illustrating the embodiment; 
         FIG. 5  is a schematic fragmentary sectional view illustrating a switch member at a sequential firing position; 
         FIG. 6  is another schematic fragmentary sectional view illustrating the switch member at the sequential firing position and a trigger being depressed without pushing a safety member against an object; 
         FIG. 7  is still another schematic fragmentary sectional view illustrating the switch member at the sequential firing position and the safety member being pushed against an object; 
         FIG. 8  is still another schematic fragmentary sectional view illustrating the switch member at the sequential firing position and the trigger being depressed after the safety member is pushed against an object; 
         FIG. 9  is still another schematic fragmentary sectional view illustrating the switch member at the sequential firing position and the trigger being continuously depressed after firing of a nail; 
         FIG. 10  is still another schematic fragmentary sectional view illustrating the switch member at a repetitive firing position; 
         FIG. 11  is still another schematic fragmentary sectional view illustrating the switch member at the repetitive firing position and the trigger being depressed without pushing the safety member against an object; and 
         FIG. 12  is yet another schematic fragmentary sectional view illustrating the switch member at the repetitive firing position, the trigger being depressed, and the safety member being pushed against an object. 
     
    
    
     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 element, which may optionally have similar characteristics. 
     Referring to  FIGS. 2 to 5 , the embodiment of the trigger assembly according to the disclosure is used in a pneumatic tool  2 . The pneumatic tool  2  includes a casing  21 , a valve rod  22  (see  FIG. 5 ) that is movably mounted to the casing  21  and that is operable to control airflow in the pneumatic tool  2  for firing a nail/nails, a safety member  23  that is movably mounted to the casing  21 , and a safety resilient member  24 . The safety member  23  has an urging end portion  231 , a connecting end portion  232  that is opposite to the urging end portion  231 , an engaging portion  233  that is located between the urging end portion  231  and the connecting end portion  232 , and two limiting blocks  236  that are respectively located at two opposite lateral sides of the engaging portion  233 . Each of the limiting blocks  236  has an inclined guide surface  234  that faces away from the connecting end portion  232 , and a limiting surface  235  that faces toward the connecting end portion  232 . The safety member  23  is movable relative to the casing  21  between a first position (see  FIGS. 5, 7, 8, 10 and 12 ) and a second position (see  FIGS. 6, 9 and 11 ). At the time that the safety member  23  is at the second position, the urging end portion  231  extends beyond a front edge of the casing  21  by an extent greater than the extent by which the urging end portion  231  extends beyond the front edge at the time that the safety member  23  is at the first position. The connecting end portion  232  of the safety member  23  is proximate to a valve seat  25  (see  FIG. 5 ) to which the valve rod  22  is mounted when the safety member  23  is at the first position, and is distal from the valve seat  25  when the safety member  23  is at the second position. The safety resilient member  24  has two opposite ends respectively abutting against the casing  21  and the safety member  23  to resiliently bias the safety member  23  toward the first position. 
     The embodiment of the trigger assembly according to this disclosure includes a trigger unit  3 , a lever member  4  and a switch unit  5 . 
     The trigger unit  3  includes a trigger  31  that is pivoted to the casing  21 , and a trigger resilient member  32 . The trigger  31  is pivotable relative to the casing  21  between a released position (see  FIGS. 5, 7 and 10 ) and a depressed position (see  FIGS. 6, 8, 9, 11 and 12 ). The trigger resilient member  32  resiliently biases the trigger  31  toward the released position. 
     The lever member  4  has a pivot portion  41  that is pivoted to the connecting end portion  232  of the safety member  23 , and an actuating portion  42  that is located between the valve rod  22  and the trigger  31   
     The switch unit  5  includes a latch member  51 , a limiting module  52 , a bolt member  53 , a latch resilient member  54  and a switch member  55 . 
     The latch member  51  is pivoted to the casing  21 , and is pivotable relative to the trigger  31 . In one embodiment, the latch member  51  and the trigger  31  are pivoted to the casing  21  by the same pivot pin. The latch member  51  has two spaced-apart side walls  511  that are respectively located at two opposite lateral sides of the trigger  31 , a stop wall  512  that is connected between distal ends of the side walls  511  distal from the trigger  31  (distal from the valve seat  25 ), and two projections  513  that are respectively formed at the side walls  511  and that are opposite to the stop wall  512 . 
     The limiting module  52  is configured to limit the range of the relative pivotal movement between the latch member  51  and the trigger  31 . In this embodiment, the limiting module  52  includes two limiting grooves  521  that are respectively formed in the side walls  511  of the latch member  51  and that are aligned with each other, and a limiting pin  522  that is mounted to the trigger  31  and that has two opposite end portions respectively slidable along the limiting grooves  521 . Each of the limiting grooves  521  has opposite first and second ends  5211 ,  5212 . 
     The bolt member  53  is mounted to the side walls  511  of the latch member  51  and is parallel to the limiting pin  522 . 
     The latch resilient member  54  is mounted to the limiting pin  522 , and has a first abutment section  541  that abuts against the casing  21 , and two second abutment sections  542  that abut against the bolt member  53 . The latch resilient member  54  resiliently biases the stop wall  512  of the latch member  51  toward the safety member  23 . 
     The switch member  55  has a main body  551  that is rotatably mounted to the casing  21  and that is partially disposed out or the casing  21  for manual operation, and a control portion  552  that is eccentric to the main body  551 . By rotating the main body  511 , the switch member  55  is movable between a sequential firing position (see  FIGS. 5 to 9 ) where the control portion  552  is separated from the path of movement of the projections  513  of the latch member  51 , and a repetitive firing position (see  FIGS. 10 to 12 ) where the control portion  552  is disposed on the path of movement of the projections  513  of the latch member  51  to prevent the latch member  51  from being moved onto the path of movement of the safety member  23 . 
     Referring to  FIGS. 5 and 10 , when the pneumatic tool  2  is not operated, the trigger  31  is at the released position, and the safety member  23  is at the first position. At this time, the latch member  51  is limited by the limiting module  52  (the end portions of the limiting pin  522  are respectively at the first ends  5211  of the limiting grooves  521 ), and is separated from the path of movement of the safety member  23 . 
     Referring to  FIGS. 5 and 6 , when the switch member  55  is at the sequential firing position and when the trigger  31  is depressed without pushing the urging end portion  231  of the safety member  23  against an object, the actuating portion  42  of the lever member  4  is moved toward the valve seat  25  by the trigger  31 , and the lever member  4  is hindered by the valve rod  22 , so the pivot portion  41  of the lever member  4  is moved away from the valve seat  25  to move the safety member  23  from the first position to the second position against the biasing action of the safety resilient member  24 , and the resultant movement of the valve rod  22  is insufficient for firing a nail. 
     At the same time, the limiting pin  522  is moved toward the safety member  23  upon depression of the trigger  31 , so the latch member  51  is permitted to be biased by the latch resilient member  54  to move onto the path of movement of the safety member  23  to engage the stop wall  512  with the engaging portion  233  of the safety member  23 . As a result, the stop wall  512  hinders the movement of the limiting blocks  236  toward the valve seat  25 , and the safety member  23  is prevented from moving to the first position for firing the nail unless the trigger  31  is released. 
     It should be noted that the movement of the latch member  51  upon depression of the trigger  31  stops after the stop wall  512  is engaged with the engaging portion  233  of the safety member  23 , and the trigger  31  can be further depressed to respectively move the end portions of the limiting pin  522  away from the first ends  5211  of the limiting grooves  521 . 
     Referring to  FIGS. 7 and 8 , when the switch member  55  is at the sequential firing position and when the trigger  31  is depressed after the urging end portion  231  of the safety member  23  is pushed against an object to maintain the safety member  23  at the first position, the actuating portion  42  of the lever member  4  is moved toward the valve seat  25  by the trigger  31 , and the pivot portion  41  of the lever member  4  is prevented from moving away from the valve seat  25  by the object. As a result, the valve rod  22  is depressed by the actuating portion  42  of the lever member  4  to move by a distance that is sufficient for firing a nail. 
     At the same time, the limiting pin  522  is moved toward the safety member  23  upon depression of the trigger  31 , so the latch member  51  is permitted to be biased by the latch resilient member  54  to move onto the path of movement of the safety member  23  to engage the stop wall  512  with the engaging portion  233  of the safety member  23  (see  FIG. 8 ). 
     Referring further to  FIG. 9 , after the firing of the nail and with the trigger  31  being continuously depressed, the casing  21  would be forced to move away from the object by a reaction force, and then he pushed against the object again. During the relative movement between the casing  21  and the object away from each other, the lever member  4  is pushed away from the valve seat  25  by the valve rod  22  to move the safety member  23  toward the second position. As a result, the limiting blocks  236  push the stop wall  512  and move past the stop wall  512  against the biasing action of the latch resilient member  54 , and the stop wall  512  is biased by the latch resilient member  54  (onto the path of movement of the safety member  23  again) to hinder the movement of the limiting blocks  236  toward the valve seat  25 , so the safety member  23  is prevented from moving to the first position for firing another nail unless the trigger  31  is released. 
     Referring to  FIG. 11 , when the switch member  55  is at the repetitive firing position and when the trigger  31  is depressed without pushing the urging end portion  231  of the safety member  23  against an object, the pivot portion  41  of the lever member  4  is moved away from the valve seat  25  to move the safety member  23  to the second position against the biasing action of the safety resilient member  24 , and the resultant movement of the valve rod  22  is insufficient for firing a nail. 
     Referring to  FIG. 12 , when the switch member  55  is at the repetitive firing position and when the trigger  31  is depressed after the urging end portion  231  of the safety member  23  is pushed against an object to maintain the safety member  23  at the first position, the actuating portion  42  of the lever member  4  is moved toward the valve seat  25  by the trigger  31 , and the pivot portion  41  of the lever member  4  is prevented from moving away from the valve seat  25  by the object, so the valve rod  22  is depressed by the actuating portion  42  of the lever member  4  to move by a distance that is sufficient for firing a nail. 
     Since the latch member  51  is separated from the path of movement of the safety member  23  by the control portion  552  of the switch member  55 , the movement of the safety member  23  is not limited by the latch member  51  when the control portion  552  is at the repetitive firing position. Therefore, the safety member  23  can be repeatedly pushed against an object/objects to move from the second position to the first position while the trigger  31  is continuously depressed so as to repeatedly fire nails. 
     By virtue of the trigger assembly of this disclosure, the pneumatic tool  2  can be operated in a sequential firing mode or a repetitive firing mode by adjusting the switch member  55 . 
     In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects. 
     While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment 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.