Abstract:
An injection device such as a syringe, which has a helical flow path for a solution in which the solvent and solute have been introduced. The helical flow path is formed by a helically configured member which has general overall configuration of a helical coil spring. Individual coils may be formed to have a groove located along the length of the helix. When compressed, the novel member effectively takes on a cylindrical outer configuration. Because the groove is covered and sealed by the surface of the next turn of the helix when compressed, an enclosed helical flow path is formed in the compressed member. The invention may be an injection device using the novel flow path forming member or alternatively, the flow path forming member itself.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to injection devices such as syringes, and more particularly to an arrangement providing an extended path for effective blending of a liquid solvent and a solid solute within the injection device. 
       SUMMARY 
       [0002]    Injection devices such as syringes are occasionally utilized to deliver liquid substances which are prepared at the last minute from solids. For example, a powdered or granular solid may be loaded into an injection device and blended with a liquid solvent within the injection device at the time of injection. 
         [0003]    There exist potential problems with delivery of fully blended solutions. One potential problem is that some substances have short life times once blended with solvents, or may present problems such as precipitation from the solution over time if prepared in advance. Another potential problem is that effective dissolving of the solid solute may possibly be incomplete. This may result in incorrect dosage or in wasteful use of potentially expensive pharmaceutical substances. 
         [0004]    As with many medical devices, injection devices entail expense. Especially with medical devices intended to be discarded after a single use, ever more complication is undesirable as it increases costs. 
         [0005]    There is a need in the prior art for injection devices which offer effective last minute blending of solid solutes with liquid solvents, yet are inexpensive. 
         [0006]    The present invention answers the above stated need by providing an effective yet inexpensive mechanism for enhancing ability of an injection device to dissolve solid solute at the time of injection. In this type of injection device, a supply of liquid solvent is maintained apart from a supply of solid solute. At the time of injection, the supply of liquid solvent is released to flow through and past the solid solute, the former dissolving the latter in so doing. 
         [0007]    In the novel approach, there is provided a helical flow path for a solution in which the solvent and solute have been introduced. The flow path is provided between the point of introduction of the liquid solvent and the solid solute and the injecting needle. The helical flow path greatly extends the effective length of the flow path within a relatively short distance within the barrel of the injection device. This promotes progressively increasing dissolution of the solid solute within the solvent. 
         [0008]    The helical flow path is provided by an advantageous construction which requires minimally expensive fabrication. Rather than forming a component of fixed geometry, such as a barrel shaped member incorporating a complicated internal passage, an inexpensively fabricated component is provided which is readily reconfigured to provide equivalent internal construction. The internal construction provides the same effectiveness of the desired flow path, but without the expense associated with the fixed geometry part. 
         [0009]    The novel member comprises a helically configured member which has general overall configuration of a helical coil spring. Rather than having a solid, circular configuration in cross section as is typical of coil spring wire, the corresponding cross section in the present invention incorporates a flow path. The novel member may be fabricated from an inexpensive flexible material such as a synthetic resin, which enables the novel member to be stretched out axially to a certain degree, and to be collapsed or compressed. When compressed, the novel member effectively takes on a configuration equivalent to the solid component of fixed geometry described above. However, fabrication costs are those of a far less complicated construction, notably, potentially being an extrusion of a linear member having suitable shaping to define a flow path. 
         [0010]    In one exemplary configuration, the cross section corresponding to the solid, circular configuration of coil spring wire is square or rectangular, with a groove formed on one exterior surface of the square or rectangle. Arbitrarily describing the groove as being formed in the top surface of the square or rectangle, upon compression of the helix, the groove will be closed by the bottom surface of the next turn of the helix. Thus there is formed a helical groove extending the full length of the compressed helix. Because the groove is covered and sealed by the surface of the next turn of the helix, an enclosed flow path is formed which extends the length of the helical groove. This helical flow path greatly increases the distance which must be negotiated by solvent and solute prior to entering the needle of the injection device. More intimate blending than would occur with straight flow paths occurs. 
         [0011]    In another exemplary configuration, no groove is provided. A flow path is nonetheless established due to action of pressure on the fluid which is forced through the helix. 
         [0012]    The helical member may be inexpensively fabricated and installed into a generally conventional injection device. The helical member may be held in the compressed configuration after assembly so that it effectively serves as a solid member having a helical internal flow passage. 
         [0013]    This construction not only promotes effective blending by maximizing flow path length, but also enables internal components of an injection device, such as a plunger, to be moved into close abutment with the flow path component, so that a high percentage of the liquid solution is successfully discharged during injection. This results in efficient use of the blended solution. 
         [0014]    It is therefore an object of the invention to promote more effective dissolution and blending of a solid solute with a liquid solvent when injecting a liquid using an injection device. 
         [0015]    It is another object of the invention to minimize costs associated with structure which promotes blending and of other structure of an injection device. 
         [0016]    It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
         [0017]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0019]      FIG. 1  is a diagrammatic side cross sectional view of an injection device incorporating the components of  FIGS. 1-3 , shown in a condition which would be seen immediately prior to commencing injection. 
           [0020]      FIG. 2  is a diagrammatic longitudinal cross section of one component of an injection device which may be provided with the benefits of the invention. 
           [0021]      FIG. 3  is a diagrammatic side cross section of two components which may be installed in the component of  FIG. 1  to establish an effective flow path for blending. 
           [0022]      FIG. 4  is a diagrammatic side elevational view of a plunger which may be installed into the component of  FIG. 1 , and which may work with the components of  FIG. 3  after the latter are installed in the component of  FIG. 2 . 
           [0023]      FIG. 5  is a diagrammatic view of one of the components of  FIG. 2 , shown axially expanded to better reveal its construction. 
           [0024]      FIG. 6  is a diagrammatic side cross sectional view of  FIG. 1 , but showing the plunger in a depressed or actuated position which would be seen at or near the completion of injection. 
           [0025]      FIG. 7  is a diagrammatic side cross sectional view of a valve which may be employed as an alternative to or in additional to a frangible barrier seen in  FIG. 1 . 
           [0026]      FIG. 8  is a diagrammatic side cross sectional view of an injection device which incorporates the valve of  FIG. 7 , shown in a condition which would be seen immediately prior to commencing injection. 
           [0027]      FIG. 9  is a diagrammatic side cross sectional view of  FIG. 8 , but showing the plunger in a depressed position which would be seen at or near the completion of injection. 
           [0028]      FIG. 10  is a cross sectional view of a valve which may be utilized as part of an injection device according to at least one aspect of the invention, shown in the closed condition. 
           [0029]      FIG. 11  is a cross sectional view of the valve of  FIG. 10 , shown in the open condition. 
           [0030]      FIG. 12  is a detail side perspective view of a barrier device which may serve as a valve for an injection device according to at least one aspect of the invention and an actuator for opening the barrier device, with the barrier device shown in the closed condition. 
           [0031]      FIG. 13  is similar to  FIG. 12 , but shows the barrier device in the open condition. 
           [0032]      FIG. 14  is similar to  FIG. 5 , but shows a component corresponding to yet differently constructed compared to that of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]      FIG. 1  of the drawings shows an injection device  10  for injecting a solution which is generated by blending of a liquid solvent  14  and a solid solute  16  which have been loaded into the injection device  10 . The injection device  10  is disposed to hold the liquid solvent  14  and the solid solute  16  apart until the moment of injection, and to intermix or blend within the injection device  10  the liquid solvent  14  and the solid solute  16 , thereby generating the solution which is to be injected. 
         [0034]    The injection device  10  may comprise a barrel  12  which is intended to contain the liquid solvent  14  and the solid solute  16 . Referring also to  FIG. 2 , the barrel  12  may comprise a lateral wall  18  having an interior surface  20 , a plunger end  22 , and an opposed delivery end  24 . A chamber  26  is defined within the interior surface  20  between the plunger end  22  and the delivery end  24 . A hollow needle  28  may be coupled to the barrel  12  at the delivery end  24  of the barrel  12 . The hollow needle  28  may have a pointed discharge end  30  adapted for example to penetrate the skin of a person for injecting medicaments, an opposed entry end  32 , and a bore  34  extending from the entry end  30  to the pointed discharge end  30 . The entry end  32  of the hollow needle  28  may be embedded in the constituent material of the delivery end  24  of the barrel  12  or otherwise sturdily coupled thereto. 
         [0035]    A fluid pathway  36  formed in the barrel  12  communicates between the chamber  26  and the bore  34  of the hollow needle  28 , thereby establishing a continuous path for liquids to traverse when being injected, although the actual path available to solution being injected is longer and less direct than suggested by  FIG. 2 . 
         [0036]    Returning to  FIG. 1 , the chamber  26  contains components which for better understanding have been shown isolated from the barrel  12  in  FIGS. 3 and 4 . As seen in  FIG. 1 , these components include a plunger  38 , which may incorporate an O-ring  40  for preventing escape of pressurized solution past the plunger  38 . The plunger  38  may be slideably engaged with the interior surface  20  of the barrel at the plunger end  22  of the barrel  12 . A barrier which may be of aluminum foil  41  may be disposed within the chamber  26 , being interposed between the plunger  38  and two additional components which may combine to establish a flow path for solution which is more intricate and effective in promoting blending of the solid solute  16  in the liquid solvent  14  than would be the case of the open chamber  26  as depicted in  FIG. 2 . 
         [0037]    One of these members is a flow path member  42 , the purpose of which is to establish a flow path along which the solution generated by blending of the liquid solvent  14  and the solid solute  16  may flow responsively to urging of the plunger  38  towards the hollow needle  28 . The plunger  38  may be generally conventional in construction and purpose, being provided to transfer manual force to liquids being injected by the injection device  10 . The flow path member  42  may be disposed between, on one hand, the liquid solvent  14  and the solid solute  16 , and on the other hand, the hollow needle  28 . 
         [0038]    The nature of the flow path member  42  is best described with reference to  FIG. 5 . The flow path member  42  may comprise an axially expansible, flexible helical member. When this flexible helical member is viewed in cross section, it may display a generally rectangular perimeter  46  which further comprises a forward axial surface  48  and a rear axial surface  50 . The forward axial surface  48  may bear a groove  52 . The flow path member  42  may be formed from a somewhat elastic member, such as a synthetic resin, so that it can be manually grasped and axially expanded, as depicted in  FIG. 5 . In the expanded condition, the flow path member may resemble a coil spring (not shown). It is not the expanded condition that is central to the invention, but rather the compressed condition seen in  FIGS. 1 and 3 . 
         [0039]    Referring particularly to  FIG. 3 , the flow path member  42  is compressible to form a cylindrical member or configuration, having a continuous cylindrical outer surface  54 , a forward axial surface  56 , and a rear axial surface  58 . In the compressed configuration of  FIGS. 1 and 3 , the groove assumes a helical configuration which tracks or mirrors the helical configuration of the flow path member  42 . However, compression of the flow path member  42  causes abutment of the forward axial surface  56  and the rear axial surface  58  of adjacent turns of the helix formed by the flow path member  42 . This closes access of the groove  52  to the exterior of the flow path member  42  along the continuous cylindrical outer surface  54 . The groove  52 , which now defines a helical flow path by virtue of being closed to the exterior of the flow path member  42 , is exposed to the exterior of the cylindrical flow path member  42  only at the forward axial surface  56  and at the rear axial surface  58  of the cylindrical flow path member  42  when the latter is compressed. 
         [0040]    In the compressed state, the flow path member  42  may form an annular member having the continuous cylindrical outer surface  54 , and also a cylindrical inner surface  60 . The cylindrical inner surface  60  may be said to define a void at the center of the compressed flow path member  42  between the forward axial surface  56  and the rear axial surface  58 . 
         [0041]    A core member  44  may be provided which cooperates closely with the compressed flow path member  42 . The core member  44  may reinforce the flow path member  42  to better maintain the annular configuration shown in  FIG. 3 . The core member  44  may also contribute to the flow path available to the solution, as will be described hereinafter. 
         [0042]    Again referring to  FIG. 1 , the barrier provided by the aluminum foil  41  separates the liquid solvent  14  from the solid solute  16  until the time of injection. At that time, manual pressure exerted on the plunger  38  from the right thereof in the depiction of  FIG. 1  in the direction of the hollow needle  28  will act to open the barrier so as to enable fluid communication between the liquid solvent  14  and the solid solute  16 , and subsequent mixing or blending of the two to generate the solution. Blending and propulsion of the liquid solvent  14  towards the hollow needle  28 , and of the solution which the liquid solvent  14  becomes as it negotiates the flow path established by the groove  52  are both consequences of the manual pressure imposed on the plunger  38 . The solution is constrained against escape from the flow path by close fit of the components of the injection device  10 , and by O-rings such as the O-ring  40  of the plunger  38  and an O-ring  62  which may be placed on the core member  44 . While sealing arising from any of the various O-rings featured herein contributes to preventing loss of solution such as past the plunger  38 , sealing especially constrains the solution against bypassing the flow path member  42 , thus assuring effective blending. 
         [0043]    The barrier separating the liquid solvent  14  from the solid solute  16  may be opened or breached in any of several ways. Notably, the barrier may be a frangible barrier which is ruptured, it may be deflected to open or expose a flow path, or it may be deformed to open or expose a flow path. 
         [0044]    The first option, that of breaking a frangible barrier, is illustrated in  FIGS. 1 and 6 .  FIG. 1  shows an initial position of the plunger  38 , wherein injection has not yet been initiated. Injection and blending are initiated by urging the plunger  38  to the left, as depicted in  FIG. 1 . In  FIG. 6 , the plunger  38  has been moved such that it has ruptured the aluminum foil  41  and has propelled the liquid solvent  14  past the solid solute  16 , through the flow path member  42 , through the fluid pathway  36  (see  FIG. 2 ), and out through the bore  34  of the hollow needle  28 . The direction of flow is indicated by an arrow  66  in  FIG. 6 . 
         [0045]    The aluminum foil  41  has been ruptured by a pointed finger  64 , best seen in  FIG. 4 , and is not shown in  FIG. 6 . The barrier provided by the aluminum foil  41  may in other forms be opened so as to enable fluid communication between the liquid solvent  14  and the solid solute  16  may comprises a finger, such as the pointed finger  66 , which is disposed to establish actuating contact with the barrier in ways other than by rupturing the barrier. 
         [0046]    Whereas in  FIG. 1  the barrier is frangible and the finger  66  pierces the barrier to open the barrier, a finger may displace a valve to open the barrier. An exemplary valve assembly  70  which may be finger operated is seen in  FIG. 7 . The valve assembly  70  may comprise a housing  72  bearing a valve flow path  74 . The valve flow path  74  may comprise an initial section  76 , a second section  78 , and a final section  80 . A valve  82  may take the form of a sphere, such as a plastic ball  82 . The plastic ball  82  may initially occupy the initial section  76 , being retained against loss by an O-ring  84 . 
         [0047]    Turning now to  FIG. 8 , there is shown an injection device  110  which is generally the structural and functional equivalent of the injection device  10  of  FIG. 1 , apart from the nature of the barrier. The valve assembly  70  described with reference to  FIG. 7  serves as the barrier in the injection device  110 . The injection device  110  may have a barrel  112 , a hollow needle  128 , a flow path member  142 , and a core member  144 , all of which may be the structural and functional respective equivalents of the barrel  12 , the hollow needle  28 , the flow path member  142 , and the core member  144 . A plunger  138  may have a blunt ended finger  164 , but in other ways may be the structural and functional equivalent of the plunger  38 . A liquid solvent  14  and a solid solute  16  are stored within and on opposing sides of the barrel  112 . 
         [0048]    In  FIG. 8 , the finger  164  is approaching the point of contact with the plastic ball  82 . As the finger  164  continues to advance to the left, as seen in  FIG. 9 , the liquid solvent  14  is propelled through the valve flow path  74  into blending contact with the solid solute  16 . The liquid solvent  14  and the solid solute  16  are then propelled through the flow path member  142 , where dissolution is furthered prior to discharge of solution through the hollow needle  128 . 
         [0049]    In summary, the barrier comprises the valve assembly  70  the plastic ball  82  of which is displaced non-axially by the finger  164  to open the barrier. 
         [0050]      FIGS. 10 and 11  illustrate a valve assembly  270  wherein the valve  282  is axially shiftable to expose a flow path  274  when the valve  282  is axially shifted to open the barrier provided by the valve assembly  270 . The valve assembly  270  may be substituted in an injection device according to at least one aspect of the invention, such as the injection device  110 . In this example, the valve assembly  70  may be omitted, with the valve assembly  270  installed thereinstead. 
         [0051]    It should be noted that in the injection devices  10  and  110 , and also with reference to the valve  270 , the barrier provided respectively by the aluminum foil  41 , the valve  70 , or the valve  270  may be operated by fluid pressure developed by the associated plungers  38  or  138  when the latter are moved as described priorly with respect to mechanical action. 
         [0052]      FIGS. 12 and 13  show a further type of barrier. In  FIG. 12 , a barrier is established by a flexible rubbery member  370 , which may be arranged to close the internal passage  374  if the rubbery member  370  is not acted on by an external element. Such an external element may be provided by a suitably configured finger  364  which may be part of an associated plunger (not shown in its entirety), such as the plunger  38  or  138 . The finger  364  may have structure such as a wing  365  for spreading open the rubbery member  370  to open the barrier established thereby to fluid communication enabling a liquid solvent such as the liquid solvent  14  to pass and blend with a solid solute such as the solid solute  16 , as occurs with the injection devices  10  and  110 . 
         [0053]      FIG. 14  shows a flow path member  142  which performs the same function as the flow path member  42  of  FIG. 5 . The difference is that the flow path member  142  has no groove such as the groove  52  of  FIG. 5 . The flow path member  142  is nonetheless operable because pressure imposed on fluid of the solution being injected slightly spreads apart adjacent coils of the flow path member, thereby establishing a flow path between adjacent coils which corresponds to the flow path which occupies the groove  52  of  FIG. 5 . 
         [0054]    The nature of the flow path member  42  is best described with reference to  FIG. 5 . The flow path member  42  may comprise an axially expansible, flexible helical member. When this flexible helical member is viewed in cross section, it may display a generally rectangular perimeter  46  which further comprises a forward axial surface  48  and a rear axial surface  50 . The forward axial surface  48  may bear a groove  52 . The flow path member  42  may be formed from a somewhat elastic member, such as a synthetic resin, so that it can be manually grasped and axially expanded, as depicted in  FIG. 5 . In the expanded condition, the flow path member may resemble a coil spring (not shown). It is not the expanded condition that is central to the invention, but rather the compressed condition seen in  FIGS. 1 and 3 . 
         [0055]    Referring particularly to  FIG. 3 , the flow path member  42  is compressible to form a cylindrical member or configuration, having a continuous cylindrical outer surface  54 , a forward axial surface  56 , and a rear axial surface  58 . In the compressed configuration of  FIGS. 1 and 3 , the groove assumes a helical configuration which tracks or mirrors the helical configuration of the flow path member  42 . However, compression of the flow path member  42  causes abutment of the forward axial surface  56  and the rear axial surface  58  of adjacent turns of the helix formed by the flow path member  42 . This closes access of the groove  52  to the exterior of the flow path member  42  along the continuous cylindrical outer surface  54 . The groove  52 , which now defines a helical flow path by virtue of being closed to the exterior of the flow path member  42 , is exposed to the exterior of the cylindrical flow path member  42  only at the forward axial surface  56  and at the rear axial surface  58  of the cylindrical flow path member  42  when the latter is compressed. 
         [0056]    In the compressed state, the flow path member  42  may form an annular member having the continuous cylindrical outer surface  54 , and also a cylindrical inner surface  60 . The cylindrical inner surface  60  may be said to define a void at the center of the compressed flow path member  42  between the forward axial surface  56  and the rear axial surface  58 . 
         [0057]    The invention may be thought of as an injection device, such as the injection devices  10  and  110 , or alternatively, as a flow path member for establishing a flow path along which a solution generated by blending of a liquid solvent and a solid solute may flow, such as the flow path member  42  or  142 . 
         [0058]    The inventive injection device may be thought of as incorporating a barrier which is opened by rupturing the barrier, as seen in the injection device  10 . Alternatively, the barrier may be deflected to open, as seen with the valves  70  and  270 . In a further variation, the barrier may be deformed to open, as seen with the rubbery member  370 . 
         [0059]    The present invention is susceptible to modifications and variations which may be introduced thereto without departing from the inventive concepts. For example, although the invention has been described with respect to a syringe, the novel principles apply equally to other devices, such as injection devices known as autoinjectors. 
         [0060]    It would be possible to provide a helical flow path member such as the flow path member  42  which has no central void, or alternatively to permit the flow path member to function on its own in the absence of a core reinforcing member such as the core member  44 . 
         [0061]    Location of a point such as that seen on the pointed finger  66  of  FIG. 4  may be relocated. For example, the core member  44  may be provided with a corresponding point to pierce a frangible barrier such as the aluminum foil  41 . 
         [0062]    While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible.