Patent Publication Number: US-2020282146-A1

Title: Single-use syringe

Description:
COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     FIELD OF THE INVENTION 
     The present invention relates to disposable and single-use syringes. 
     BACKGROUND OF THE INVENTION 
     The need for a single-use syringe comes from the concern in the transfer of infectious diseases such as AIDS, and more particularly in some intravenous drug users who routinely share and reuse syringes. Although there are certain regulations and procedures for the proper disposal of used syringes, failure of following such regulations and procedures often occur, many due to emergency circumstances, negligence, and abuse. 
     There are many different designs of single-use syringes in the art. However, none possesses all the desirable features of user friendliness, simplicity, and reliability in both usage and fabrication. Lacking self-containments of all parts is also an impediment to the wide adoption of single-use syringes. 
     SUMMARY 
     It is the objective of the present invention to provide a single-use syringe that addresses the aforementioned and other needs. Embodiments of the present invention can be used as epidural needles and other applications of fluid and gas discharging. 
     In accordance to an embodiment of the present invention, provided is a syringe comprises a barrel resembling a cylindrical tube, an upper plunger, a lower plunger, a plunger seal, and a needle adaptor or nozzle. The barrel comprises an open top end, a bottom end connected to the needle adaptor or nozzle, and a first resilient unidirectionally-biased peripheral annulus formed inside the barrel and approximately near the top end opening. 
     The upper plunger is configured for moving axially inside the barrel. The upper plunger has a dome or cone shaped bottom mounted at a first end of the upper plunger, a first flange formed at a second end and a second flange formed adjacent to the first flange. 
     The lower plunger is a cylindrical tube with an opened first end and an opened or closed second end. The lower plunger comprises a second resilient unidirectionally-biased peripheral annulus formed near the first end and a third resilient unidirectionally-biased peripheral annulus formed further inside the lower plunger. The space between the second annulus and the third annulus defines a holding chamber that holds the dome or cone shaped bottom of the upper plunger. The plunger seal is installed at the second end of the lower plunger and is intimate contact with the inner wall of the barrel, providing the sealing function. 
     Before the fluid or gas intake and expel actions, the upper plunger is connected with the lower plunger in that the dome or cone shaped bottom of the upper plunger is inserted into the lower plunger, passing the second resilient unidirectionally-biased peripheral annulus and just pressing against the third resilient unidirectionally-biased peripheral annulus. The third resilient unidirectionally-biased peripheral annulus provides just enough resilience against the pushing force of the dome or cone shaped bottom of the upper plunger to actuate the lower plunger when the upper plunger is inserted further into the barrel during fluid or gas expel action. 
     When the lower plunger reaches and stops at the bottom end of the barrel, further pushing force of the dome or cone shaped bottom of the upper plunger against the third resilient unidirectionally-biased peripheral annulus causes the dome or cone shaped bottom to breach the third annulus, and simultaneously the second flange to breach first resilient unidirectionally-biased peripheral annulus inside the barrel. The dome or cone shaped bottom is then entirely trapped inside the lower plunger, and the second flange is trapped by the first resilient unidirectionally-biased peripheral annulus inside the barrel. As such, the upper plunger is locked in the barrel, preventing any subsequent fluid/gas intake action. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements and in which: 
         FIG. 1  is an exploded view of a syringe in accordance with an embodiment of the present invention; 
         FIG. 2  is a close-up perspective view of a barrel of the syringe in accordance with an embodiment of the present invention; 
         FIG. 3  is a close-up perspective view of a lower plunger of the syringe in accordance with an embodiment of the present invention; and 
         FIGS. 4, 5, 6, and 7  are schematic diagrams illustrating the usage of the syringe in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, syringes and the likes are set forth as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions may be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention; however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation. 
     Referring to  FIGS. 1 and 2 .  FIG. 1  is an exploded view of a syringe in accordance with an embodiment of the present invention;  FIG. 2  is a close-up view of the barrel of the syringe in accordance with an embodiment of the present invention. As shown in  FIGS. 1 and 2 , a syringe  2  is provided, which comprises a barrel  21  resembling a cylindrical tube, an upper plunger  3 , a lower plunger  4  and a plunger seal  5 , and a needle adaptor or nozzle  20 . If the syringe  2  is configured for the use of an epidural needle, a needle assembly  1  is connected to the needle adaptor  20 . 
     The barrel  21  comprises an open top end, a bottom end having a shoulder  22  and connected to the needle adaptor or nozzle  20 , and a first resilient unidirectionally-biased peripheral annulus  23  formed inside the barrel  21  and approximately near the top end opening. 
     The upper plunger  3  is configured for moving axially inside the barrel  2 . The upper plunger  3  has a dome or cone shaped bottom  30  mounted at a first end of the upper plunger  3 , a first flange  31  formed at a second end and a second flange  32  formed adjacent to the first flange  31 . 
     As shown in  FIG. 2 , in one embodiment, the first resilient unidirectionally-biased peripheral annulus  23  of the barrel  21  comprises multiple transverse protuberances, and each protuberance projecting downwardly from an inner wall of the barrel  21 . The third flange  24  is formed on an outer wall of the barrel  21  corresponded to the first resilient unidirectionally-biased peripheral annulus  23 . 
     With further reference to  FIG. 3 .  FIG. 3  is a close-up perspective view of a lower plunger of the syringe in accordance with an embodiment of the present invention. In this embodiment, the lower plunger  4  is a cylindrical tube with an opened first end and an opened or closed second end. The lower plunger  4  comprises a second resilient unidirectionally-biased peripheral annulus  40  formed near the first end and a third resilient unidirectionally-biased peripheral annulus  41  formed further inside the lower plunger  4 . The space between the second resilient unidirectionally-biased peripheral annulus  40  and the third resilient unidirectionally-biased peripheral annulus  41  defines a holding chamber that holds the dome or cone shaped bottom  30  of the upper plunger  3 . The plunger seal  5  installed at the second end of the lower plunger  4  and is intimate contact with the inner wall of the barrel  21 , providing the sealing function. 
     Before the fluid or gas intake and expel actions, the upper plunger  3  is connected with the lower plunger  4  in that the dome or cone shaped bottom  30  of the upper plunger  3  is inserted into the lower plunger  4 , passing the second resilient unidirectionally-biased peripheral annulus  40  and just pressing against the third resilient unidirectionally-biased peripheral annulus  41 . The third resilient unidirectionally-biased peripheral annulus  41  provides just enough resilience against the pushing force of the dome or cone shaped bottom  30  of the upper plunger  3  to actuate the lower plunger  4  when the upper plunger  3  is inserted further into the barrel during fluid or gas expel action. 
     When the lower plunger  4  reaches and stops at the bottom end of the barrel  21 , further pushing force of the dome or cone shaped bottom  30  of the upper plunger  3  against the third resilient unidirectionally-biased peripheral annulus  41  causes the dome or cone shaped bottom  30  to breach the third annulus  41 , and simultaneously the second flange  32  to breach first resilient unidirectionally-biased peripheral annulus  23  inside the barrel  21 . The dome or cone shaped bottom  30  is then entirely trapped inside the lower plunger  4  passed the third annulus  41  (in the locking chamber, which is the space between the third annulus  41  and the second end of the lower plunger  4 ), and the second flange  32  is trapped by the first annulus  23  inside the barrel. As such, the upper plunger  3  is locked in the barrel  21 , preventing any subsequent fluid/gas intake action. 
     In accordance to one embodiment, the second resilient unidirectionally-biased peripheral annulus  40  is formed with multiple transverse protuberances, and each protuberance projecting downwardly from an inner wall of the lower plunger  4 . The third resilient unidirectionally-biased peripheral annulus  41  comprises multiple transverse protuberances projecting radially from the inner wall of the lower plunger. 
     Referring to  FIGS. 4 to 7 .  FIG. 4  illustrates the syringe in an initial state in accordance with an embodiment of the present invention;  FIG. 5  illustrates the syringe is in a pulling state;  FIG. 6  illustrates the syringe is in a pushing state; and  FIG. 7  illustrates the syringe in a locked state. 
     Initially, as shown in  FIG. 4 , the assembly of the upper plunger  3 , lower plunger  4 , and the plunger seal  5  is moved toward the needle adaptor or nozzle  20  that connects to the bottom end of the barrel  21  (e.g., the shoulder  22  of the barrel  21 ), which in order to remove all air before a fluid/gas intake action. The dome or cone shaped bottom  30  is firmly held inside the holding portion  60 . In other words, the lower plunger  4  is engaged to the upper plunger  3 . 
     The third resilient unidirectionally-biased peripheral annulus  41  of the lower plunger  4  prevents the upper plunger  3  going totally inside the lower plunger  4  when a person pushing too hard on the first flange  31  for removing air. 
     Filling the syringe with medicine after air being discharged, as shown in  FIG. 5 , the upper plunger  3  is pulled with the lower plunger  4  moving toward the first resilient unidirectionally-biased peripheral annulus  23 . The upper plunger  3  stopped when the fluid or gas is drawn up to a desired amount. The first resilient unidirectionally-biased peripheral annulus  23  ensures the upper plunger  3  cannot be pulled out from the barrel  21 , and the second resilient unidirectionally-biased peripheral annulus  40  prevents the upper plunger  3  being pull out from the lower plunger  4 . 
     In a fluid or gas expel action, the upper plunger  3  is then pushed, as shown in  FIG. 6 , to actuate the lower plunger  4  to move toward the shoulder  22  until the plunger seal  5  reaches the bottom end of the barrel  21  to complete the entire fluid or gas expel. 
     After the completion of the fluid or gas expel, as shown in  FIG. 7 , the upper plunger  3  is then pushed further to force the dome or cone shaped bottom  30  pass the third resilient unidirectionally-biased peripheral annulus  41 . The dome or cone shaped bottom  30  is then entirely trapped inside the locking portion  61  of the lower plunger  4 . Simultaneously, the second flange  32  breaches the first resilient unidirectionally-biased peripheral annulus  23  inside the barrel. Eventually, the upper plunger  3  is locked, preventing the upper plunger  3  from pulling out of the barrel  21 . As such, the syringe is rendered usable. 
     It is noted that the first, second, and third resilient unidirectionally-biased peripheral annulus are formed with multiple transverse protuberances projecting downwardly from the surrounding walls. Once the upper plunger is locked, applying external force for detachment will break the protuberances. A skill person in the art can appreciate that other mechanical mechanisms may be adopted in place of the multiple transverse protuberances to achieve the same function without undue experimentation or deviation from the spirit of the present invention. 
     The embodiments described above do not require any additional and/or external means or components to prevent the syringe from being reused once locked. Thus, the syringe of the present invention provides the desirable features of user friendliness, simplicity, and reliability in both usage and fabrication, along with a self-containment of all parts. 
     While the disclosure has been described in connection with a number of embodiments and implementations, the disclosure is not so limited but covers various obvious modifications and equivalent arrangements, which fall within the purview of the appended claims. Although features of the disclosure are expressed in certain combinations among the claims, it is contemplated that these features can be arranged in any combination and order.