Patent Publication Number: US-8966771-B2

Title: Out of front knife with assisted opening mechanism

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an out of front knife with an assisted opening mechanism, especially to an out of front knife that has a blade that must be moved manually a preset distance and overcome a preset resistance, such that a spring inside the out of front knife will help the blade to move to be extended out. 
     2. Description of the Prior Art(s) 
     An out of front knife has a handle and a blade that is able to slide directly forward to extend out of the handle. The out of front knife has existed and long been popular among general republic due to its portability and user friendly design. A conventional out of front knife further has a spring mechanism and a locking mechanism. The spring mechanism is connected to the handle and the blade, and is able to pull the blade to assist the blade to extend out of the handle. The locking mechanism locks the blade at an open position or a closed position, and prevents the blade from being retracted or extended accidentally. 
     However, once the locking mechanism does not lock the blade well, the spring mechanism is very likely to automatically pull the blade to quickly extend out of the handle and injure people when the conventional out of front knife is bumped or any other accident happens. Therefore, the conventional out of front knife is dangerous and in some countries is regulated by laws and restricted to registered users only. 
     To overcome the shortcomings, the present invention provides an out of front knife with an assisted opening mechanism to mitigate or obviate the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide an out of front knife with an assisted opening mechanism. The out of front knife has a handle, a blade mounted in the handle, a thumb stud that drives the blade, and an extending assembly that assists with extending the blade out of the handle. 
     With two sliders and two springs of the extending assembly, only when the blade is intentionally pushed to move a preset distance and overcome a preset resistance, one of the springs pulls and assists the blade of the out of front knife to extend out of the handle. Therefore, the out of front knife with the assisted opening mechanism is used safely. 
     Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an out of front knife with an assisted opening mechanism in accordance with the present invention; 
         FIG. 2  is an exploded perspective view of the out of front knife in  FIG. 1 ; 
         FIG. 3  is another exploded perspective view of the out of front knife in  FIG. 1 ; 
         FIG. 4  is an operational side view of the out of front knife in  FIG. 1 , showing a blade is retraced in a handle and a pressing protrusion of a retainer presses against a retracting limiting end of a resilient rod; 
         FIG. 5  is an operational side view of the out of front knife in  FIG. 1 , showing the blade is retraced in the handle and the pressing protrusion of the retainer is away from the retracting limiting end of the resilient rod; 
         FIG. 6  is an operational side view of the out of front knife in  FIG. 1 , showing the blade is partially extended; 
         FIG. 7  is an operational side view of the out of front knife in  FIG. 1 , showing the blade is extended and an extending limiting end of the resilient rod abuts an inner end of the blade; and 
         FIG. 8  is an operational side view of the out of front knife in  FIG. 1 , showing the blade is extended and the extending limiting end of the resilient rod is away from the inner end of the blade. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     With reference to  FIGS. 1 and 2 , an out of front knife with an assisted opening mechanism in accordance with the present invention comprises a handle  10 , a blade  21 , a thumb stud  22 , an extending assembly  30 , an engaging member  40 , a retainer  50  and an unlock panel  60 . 
     With further reference to  FIG. 3 , the handle  10  has a rear closed end, a front opening end  101 , a sidewall, a front wall (a wide wall), an inner surface, a sliding slot  102 , a first through hole  103 , a second through hole  104  and at least one guiding protrusion  105 . The sliding slot  102  of the handle  10  is formed through the sidewall of the handle  10  and has two ends respectively extending toward the rear closed end and the front opening end  101  of the handle  10 . The first through hole  103  and the second through hole  104  are separately formed through the front wall of the handle  10 . Each of the first and the second through holes  103 ,  104  has two ends respectively extending toward the rear closed end and the front opening end  101  of the handle  10 . The at least one guiding protrusion  105  is formed on the inner surface of the handle  10 . 
     In the preferred embodiment of the present invention, the handle  10  is formed from a front casing  11 , a rear casing  12  and a guiding panel  13 . The first through hole  103 , the second through hole  104  and the sliding slot  102  of the handle  10  are formed through the front casing  11 . The at least one guiding protrusion  105  of the handle  10  is formed on an inner surface of the front casing  11 . The front casing  11  further has a mounting recess  111  formed in a rear end of the front casing  11 . The rear casing  12  corresponds to and is securely mounted on the front casing  11  and has a mounting recess  121  formed in a rear end of the rear casing  12  and corresponding to the mounting recess  111  of the front casing  11 . The guiding panel  13  is held between the front casing  11  and the rear casing  12  and has a guiding slot  131  and an engaging recess  132 . The guiding slot  131  of the guiding panel  13  is formed through the guiding panel  13 . The engaging recess  132  of the guiding panel  13  is formed in a rear end of the guiding panel  13  and corresponds to the mounting recesses  111 ,  121  of the front casing  11  and the rear casing  12 . 
     The blade  21  is slidably mounted through the front opening end  101  of the handle  10  and has an inner end protruding in the handle  10 . The thumb stud  22  is mounted beside the handle  10 , protrudes through the sliding slot  102  of the handle  10  and is securely connected to the blade  21 . When the thumb stud  22  is pushed, the thumb stud  22  and the blade  21  move along the sliding slot  102  of the handle  10  simultaneously. 
     The extending assembly  30  is mounted in the handle  10  and has a positioning frame  33 , a first slider  31 , a second slider  32 , at least one fastener  34 , an extending spring  35  and a retracting spring  36 . 
     The positioning frame  33  is securely mounted in the handle  10 , is held between the front casing  11  and the guiding panel  13 , and has a front end, a rear end, a side edge, a sliding slot  331 , a connecting protrusion  332 , a resilient rod  333  and a mounting recess  336 . The sliding slot  331  of the positioning frame  33  is formed through the positioning frame  33  and has two ends respectively extending toward the rear closed end and the front opening end  101  of the handle  10 . The connecting protrusion  332  is disposed on the front end of the positioning frame  33 . The resilient rod  333  is disposed on the side edge of the positioning frame  33  and has a retracting limiting end  334  and an extending limiting end  335 . The retracting limiting end  334  corresponds to the rear closed end of the handle  10 . The extending limiting end  335  corresponds to the front opening end  101  of the handle  10 . The mounting recess  336  of the positioning frame  33  is formed in the rear end of the positioning frame  33  and corresponds to the engaging recess  132  of the guiding panel  13  and the mounting recesses  111 ,  121  of the front casing  11  and the rear casing  12 . 
     The first slider  31  is disposed beside the positioning frame  33  and has a front end, a rear end, a sliding slot  311 , two connecting protrusions  312  and an abutting portion  313 . The sliding slot  311  of the first slider  31  is formed through the first slider  31 , corresponds to the sliding slot  331  of the positioning frame  33 , and has two ends respectively extending toward the rear end of the first slider  31  and the front end of the first slider  31 . The connecting protrusions  312  of the first slider  31  are separately disposed on the rear end of the first slider  31 . The abutting portion  313  is formed on the front end of the first slider  31 . 
     The second slider  32  is disposed beside the first slider  31  and has a front end, a rear end, a sliding slot  321 , a connecting protrusion  322  and a pushing portion  323 . The sliding slot  321  of the second slider  32  is formed through the second slider  32 , corresponds to and is shorter than the sliding slot  311  of the first slider  31 , and has two ends respectively extending toward the rear end of the second slider  32  and the front end of the second slider  32 . The connecting protrusion  322  of the second slider  32  is disposed on the front end of the second slider  32 . The pushing portion  323  is formed on the front end of the second slider  32 . 
     The at least one fastener  34  is mounted through the sliding slots  321 ,  311 ,  331  of the second slider  32 , the first slider  31  and the positioning frame  33  and is securely attached to the inner end of the blade  21 . Thus, as the blade  21  moves, the first slider  31  and the second slider  32  move along the sliding slot  331  of the positioning frame  33  simultaneously. 
     The extending spring  35  is a tension spring and has two ends respectively connected to the connecting protrusion  332  of the positioning frame  33  and one of the connecting protrusions  312  of the first slider  31 . The retracting spring  36  is a compression spring and has two ends respectively connected to the other one of the connecting portions  312  of the first slider  31  and the connecting protrusion  322  of the second slider  32 . 
     The engaging member  40  is mounted through the mounting recesses  111 ,  121 ,  336  of the front casing  11 , the rear casing  12  and the positioning frame  33 , and engages the engaging recess  132  of the guiding panel  13  to hold the guiding panel  13  and the positioning frame  33  firmly in the handle  10 . 
     The retainer  50  is mounted in the handle  10 , is disposed beside the resilient rod  333  of the positioning frame  33  and has a switch button  51  and a pressing protrusion  52 . The switch button  51  of the retainer  50  is mounted through the first through hole  103  of the handle  10  and protrudes out of the handle  10  to allow the retainer  50  to be moved. The pressing protrusion  52  corresponds to the retracting limiting end  334  of the resilient rod  333  and selectively presses against the retracting limiting end  334 . 
     The unlock panel  60  is slidably mounted in the handle  10 , is disposed between the blade  21  and the front casing  11 , and has at least one guiding slot  61 , a switch button  62  and a pushing protrusion  63 . The at least one guiding slot  61  of the unlock panel  60  is formed through the unlock panel  60 . Each of the at least one guiding slot  61  of the unlock panel  60  is mounted around a corresponding one of the at least one guiding protrusion  105  of the handle  10  and has two ends respectively extending toward the rear closed end and the front opening end  101  of the handle  10 . Thus, the unlock panel  60  slides relative to the handle  10  along a specific direction. The switch button  62  of the unlock panel  60  is mounted through the second through hole  104  of the handle  10  and protrudes out of the handle  10  to allow the unlock panel  60  to be moved. The pushing protrusion  63  corresponds to the extending limiting end  335  of the resilient rod  333  and selectively pushes the extending limiting end  335 . 
     With reference to  FIG. 4 , when the blade  21  of the out of front knife is retracted in the handle  10 , the retracting limiting end  334  of the resilient rod  333  abuts the abutting portion  313  of the first slider  31 . Furthermore, the retainer  50  is switched to allow the pressing protrusion  52  to press against the retracting limiting end  334  of the resilient rod  333  and to ensure that the retracting limiting end  334  of the resilient rod  333  does not leave the abutting portion  313  of the first slider  31 . Consequently, the blade  21  does not accidently extend out of the handle  10 . 
     With further reference to  FIGS. 5 and 6 , when the retainer  50  is switched and the pressing protrusion  52  of the retainer  50  is away from the retracting limiting end  334  of the resilient rod  333 , the thumb stud  22  as well as the blade  21  is capable of being pushed to move toward the front opening end  101  of the handle  10 . Moreover, the second slider  32  also moves together with the blade  21  and the thumb stud  22  via the at least one fastener  34  for a short distance. Until the pushing portion  323  of the second slider  32  pushes the retracting limiting end  334  of the resilient rod  333  away from the abutting portion  313  of the first slider  31 , the extending spring  35  pulls the first slider  31 , the second slider  32  and the blade  21  to move toward the front opening end  101  of the handle  10 . Thus, the blade  21  is assisted to be extended out of the handle  10 . 
     When the thumb stud  22  and the blade  21  are pushed, the second slider  32  is driven and the retracting spring  36  is compressed first, and then the first slider  31  is moved via the at least one fastener  34  later. If a force applied to the thumb stud  22  and the blade  21  is unable to allow the pushing portion  323  of the second slider  32  to push the retracting limiting end  334  of the resilient rod  333  to depart from the abutting portion  313  of the first slider  31 , the retracting spring  36  pulls the second slider  32 , the blade  21  and the thumb stud  22  back to a retracting position. If the thumb stud  22  is just bumped by accident rather than intentionally pushed to drive the blade  21  to push the retracting limiting end  334  of the resilient rod  333 , the blade  21  is not extended out. Therefore, the out of front knife in accordance with the present invention can be used safely. 
     With reference to  FIG. 7 , after the extending spring  35  pulls the blade  21  to fully extend the blade  21  of the handle  10 , the extending limiting end  335  of the resilient rod  333  abuts the inner end of the blade  21 . Thus, the blade  21  would not be retracted into the handle  10  by any unexpected force. 
     With further reference to  FIG. 8 , when the unlock panel  60  is switched to allow the pushing protrusion  63  of the unlock panel  60  to push the extending limiting end  335  of the resilient rod  333  away from the inner end of the blade  21 , the thumb stud  22 , the blade  21 , the first slider  31  and the second slider  32  can be pushed to move toward the rear closed end of the handle  10  to retract the blade  21  into the handle  10 . Until the retracting limiting end  334  of the resilient rod  333  abuts the abutting portion  313  of the first slider  31 , the blade  21  is securely held in the handle  10 . 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.