Abstract:
An injection device has a housing ( 50, 60 ) and therein a spring for storing energy for an injection operation. The spring ( 94 ) impinges, in the proximal direction, upon an ejection member ( 92 ) for ejecting injection liquid ( 16 ) from a vessel, displaceably arranged in the housing, at whose proximal end an injection needle is attached. Located in the housing is a displacement member ( 36 ), displaceable in the longitudinal direction, for displacing the vessel ( 14 ) in the proximal direction, in order to effect a movement of the injection needle ( 18 ) in the proximal direction and, thus, its insertion. Provided on the ejection member ( 92 ) is a detent lug ( 100 ), associated with which is a corresponding detent opening ( 102 ) in the displacement member ( 36 ). A control member ( 70 ), effective in travel-dependent fashion, serves to disengage the detent lug ( 100 ) from the detent opening ( 102 ) when the displacement member ( 36 ), during the injection operation, has traveled a predefined distance in the proximal direction.

Description:
FIELD OF THE INVENTION 
     The invention concerns an injection device having a housing and having an energy storage spring for storing energy for an injection operation. This energy serves preferably for automatically inserting an injection needle, and optionally also for automatic injection of an injection liquid. The preferred field of application of the invention is an injection device for one-time use, often also referred to as a disposable syringe. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to make a new injection device available. 
     According to the invention, this object is achieved by having a control member which disengages a detent lug once a displacement member has traveled a predefined distance in the proximal direction. What is thereby obtained, in simple fashion, is sequential execution of the injection operation, i.e. first the injection needle (hollow needle) is inserted into the patient, and only then, when the needle is already in the subcutaneous fatty tissue, is the active ingredient present in the injection device injected. 
     Another way of achieving the stated object is to use a spring-loaded needle protection sleeve. Because the proximal and distal end positions of the needle protection sleeve are a function of the position of the vessel container and thus of the displacement member, these end positions can be optimally adapted to requirements before and after an injection. 
     Further details and advantageous developments of the invention are evident from the exemplary embodiment described below and depicted in the drawings, which is in no way to be understood as a limitation of the invention. 
    
    
     BRIEF FIGURE DESCRIPTION 
     In the drawings: 
     FIG. 1 shows an injection device according to the present invention in longitudinal section and in its cocked position, i.e. the position before an injection, and at enlarged scale; in reality, the device depicted in FIG. 1 has, for example, a length of approximately 18 cm and has approximately the shape of an oversized fountain pen; 
     FIG. 2 is a plan view of the point shown cut away in FIG. 1, view in the direction of arrow II of FIG. 1; 
     FIG. 3 is a more greatly enlarged depiction of the upper half of the injection device of FIG. 1 with the device in the cocked position, i.e. before an injection operation; 
     FIG. 4 is a view similar to FIG. 3 but after initiation of an injection operation, although the needle has merely been inserted whereas an injection has not yet taken place; 
     FIG. 5 is a view similar to FIGS. 3 and 4, but after an injection has been completely performed; and 
     FIGS. 6-8 are schematic depictions to explain the sequential execution of an injection; 
     FIG. 9 shows the proximal portion of the injector before removal of the needle cover cap which covers the hollow needle in sterile fashion; 
     FIG. 10 is a perspective view for better comprehension of FIG. 9; 
     FIG. 11 is a perspective view of the proximal end segment of the needle protection sleeve; 
     FIG. 12 is a view of the proximal portion of the injector upon removal of the needle cover cap; 
     FIG. 13 is a perspective view for better comprehension of FIG. 12; 
     FIG. 14 is a view of the proximal portion of the injector after the needle has been inserted into the subcutaneous fatty tissue of the patient; 
     FIG. 15 is a view of the proximal portion of the injector after the needle has been pulled out; the latter is, in this context, completely surrounded by the needle protection sleeve to prevent anyone from being injured by the needle or infected with a disease; 
     FIG. 16 is a plan view of an arrangement of barbs provided on the needle protection sleeve; 
     FIG. 17 is a longitudinal section viewed along line XVII—XVII of FIG. 16; 
     FIG. 18 is a schematic view of the barb arrangement before becoming effective; and 
     FIG. 19 is a schematic view of the barb arrangement after becoming effective. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the description which follows, the terms “proximal” and “distal” are used in the manner usual in medicine, i.e. “proximal”=facing toward the patient (the end of the injection device having injection needle  18 ), and “distal”=facing away from the patient. 
     FIG. 1 shows the totality of an injection device  10  in longitudinal section. In the exemplary embodiment, this is an injection device for one-time use, also called an autoinjector, but the invention can also be used in the context of injection devices that allow multiple use. In this embodiment, there is located in the interior of injection device  10  an injection syringe  12  of commercially available design, having a cylindrical portion  14  to receive the injection liquid  16 , at whose proximal end an injection needle  18  is attached in the usual fashion. 
     Cylindrical portion  14  has at the top, in the usual fashion, an enlargement  20  in the form of so-called syringe flanges. Also provided is a piston  22  that is connected to a piston rod  24  that has a pressure plate  26  at its distal end. When pressure is exerted on pressure plate  26  in the direction of arrow  28 , liquid  16  is then ejected through needle  18 , as is familiar to those skilled in the art. 
     Cylindrical portion  14  of commercially available syringe  12  is located in the cylindrical recess  29  of a vessel container  30 , which can also be referred to as the syringe container and which has at its distal end region a shoulder  32  against whose distal side enlargement  20  rests as depicted. Shoulder  32  transitions into a collar-shaped segment  34  that, as depicted, is firmly connected to a displacement member  36 , of substantially cylindrical configuration, which with its proximal end  38  grips syringe flanges  20  so that the latter are firmly connected to displacement member  36  and vessel container  30 , and syringe  12  constrainedly follows their movements. 
     Vessel container  30  has in the proximal end region two grooves or recesses  40 ,  40 ′ which lie diametrically opposite one another. A needle protection sleeve  46  has two resilient segments  42 ,  44 , each with a radially inwardly protruding projection  42 ′,  44 ′ at its free end. Projection  42 ′ protrudes into groove  40 , projection  44 ′ into groove  40 ′. FIG. 2 shows resilient segment  42  in plan view. 
     Needle protection sleeve  46  is thus displaceable between a proximal and a distal end position, whose spacing is determined by the (identical length of grooves  40 ,  40 ′. As vessel container  30  is displaced in the proximal direction upon injection, the position of grooves  40 ,  40 ′ also changes, and thus so do the proximal and distal end positions of needle protection sleeve  46  as will be described in detail below, i.e. both end positions are then displaced in the proximal direction. Grooves  40 ,  40 ′ also effect longitudinal guidance of needle protection sleeve  46 . 
     Needle protection sleeve  46  is slidingly displaceable in cylindrical inner side  52  of a proximal housing portion  50 . From cylindrical inner side  52 , an annular shoulder  54  protrudes radially inward. This serves an abutment for a compression spring  56  which, as depicted, acts upon needle protection sleeve  46  in the proximal direction, i.e. toward the patient. 
     Collar-shaped segment  34  is also displaceable in cylindrical inner side  52  as depicted, specifically from its distal end position depicted in FIGS. 1 and 3 to its proximal end position depicted in FIGS. 4 and 5, in which segment  34  is in contact against annular shoulder  54 . 
     Firmly connected to proximal housing portion  50 , as depicted, is a distal housing portion  60 . The latter has an interior space  62  that is closed off at the top, i.e. at the distal end, by a closure wall  64 . Located on the outer side of housing portion  60 , in an annular groove  66 , is a rotatable annular element  68  that has a control member or cam segment  70  which projects through an opening  72 , as depicted, into the interior of distal housing portion  60 . 
     Located on the outer side of distal housing portion  60 , as depicted, is a triggering member  74  that has approximately the shape of the retaining clip of a fountain pen. In the region of its unattached (proximal) end, triggering member  74  has a radially inwardly protruding projection  76  which serves to trigger an injection operation. In FIG. 1, this is prevented by annular element  68 , which is in its locking position and thus blocks any movement of projection  76  to the left. FIGS. 3 through 5 show this annular element  68  in a rotational position in which it makes possible the triggering of an injection, because there is present therein, opposite projection  76 , a recess  80  of annular element  68  which then aligns with a recess  82  of distal housing portion  60 . 
     As FIG. 1 shows, in the cocked state a radially outwardly deflecting detent element  84 , which in this case is configured integrally with displacement member  36 , snaps into recess  82 . Associated with this detent element  84  on the inner side of distal housing portion  60  is a longitudinal groove  86  in which detent element  84  is displaced during the injection operation (cf. FIGS.  4  and  5 ). 
     An ejection member  92  is arranged in slidingly displaceable fashion in cylindrical inner side  90  of displacement member  36 . It is acted upon in the proximal direction by a compression spring  94  that, in the cocked state (FIGS.  1  and  3 ), stores the energy necessary for performing an injection operation. As depicted, spring  94  is braced at its distal end against housing segment  64 , and at its proximal end against an annular shoulder  96  of ejection member  92 . 
     Ejection member  92  is configured integrally with a flexible detent member or lug  100  whose form and function are best evident from FIGS. 6 through 8. When injection device  10  is in the cocked state (FIGS.  1  and  3 ), detent member  100  projects into a detent opening or recess  102  of displacement member  36 , and through this recess  102  it projects with a radial protrusion  103  radially outward into a radial space or gap  104  between displacement member  36  and inner side  106  (FIGS. 6 and 7) of distal housing portion  60 . In that context, it is braced at a radially extending surface  108  against a corresponding countersurface of opening or recess  102 , as shown in greatly magnified fashion in FIG. 6, so that the force of spring  94  is transferred via detent member or lug  100  to displacement member  36 , and acts upon the latter in the proximal direction before an injection begins. 
     Mode of operation 
     In order to trigger an injection, in FIG. 3 member  74  is acted upon by a force F and thereby displaces resilient detent member  84  of displacement member  36  radially inward, so that the latter comes out of engagement with recess  82  of distal housing portion  60 . 
     As a result, as shown in FIG. 4, ejection member  92  and displacement member  36  can be displaced together in the proximal direction in response to cocked spring  94 , since they are coupled to one another by flexible detent member or lug  100 , and needle  18  is thus displaced into the position labeled  18 ′ in FIG. 1, thus inserting it into the subcutaneous fatty tissue of the patient (cf. FIG.  14 ). 
     As shown in FIG. 4, in this context an axial gap  110  initially remains between proximal end  112  of ejection member  92  and pressure plate  26 , since the syringe  12  moves synchronously with displacement member  36  and consequently the positions of these parts relative to one another do not change. The size of gap  110  depends on the magnitude of liquid volume  16  in syringe  12 . 
     When the position shown in FIG. 4 is reached, flexible detent member  100  is deflected radially inward by projection  70  so that it comes out of engagement with recess  102  of displacement member  36 . 
     The manner in which this occurs is shown by FIGS. 6 through 8, which actually require no explanation. Projection  70  has on its distal side an oblique surface that, on radial protrusion  103 , corresponds to a complementary oblique surface  114  of flexible detent member or lug  100 . When a movement occurs in the direction of arrow  28 , oblique surfaces  112  and  114  slide along one another and push flexible detent member  100  radially inward in the direction of an arrow  116 , so that (as shown in FIG. 7) it comes out of engagement with the associated recess  102  of displacement member  36  and (as shown in FIG. 8) moves automatically in the proximal direction in response to compression spring  94 . 
     In this context, as shown in FIG. 5, proximal end face  112  of ejection member  92  presses against pressure plate  26  and displaces the latter as far as the stop in the commercially available syringe  12 , so that the liquid  16  is ejected from the latter and injected through needle  18  into the patient. FIG. 5 shows the position that is reached after completion of the (automatically proceeding) injection operation. 
     FIG. 9 is largely the same as the depiction of FIG.  1 . It shows the manner in which, prior to an injection, a sterile needle cover cap  120  must be pulled off in the direction of an arrow  122  so that the needle can be inserted. In the present case, removal of needle cover cap  120  would be possible only with the aid of a forceps. 
     For this reason, needle protection sleeve  46  has two radial projections  124 ,  126  with which it projects into axially extending cutouts  128 ,  130  of proximal housing portion  50  and is axially displaceable in those cutouts. 
     FIG. 11 shows, in a perspective depiction, the proximal portion of needle protection sleeve  46 . This also has a detent arrangement  132  having two resilient barbs  134 ,  136  that are located in a window  138 . Arrangement  132  and its function are explained below. As clearly depicted in FIG. 17, barbs  134 ,  136  project inward and outward radially beyond inner circumference  46 ′ and outer circumference  46 ′′, respectively, of needle protection sleeve  46 . The outward protrusion provides guidance in a longitudinal groove  154  of housing portion  50 , as depicted in FIGS. 18 and 19. The purpose of the inward protrusion is to deflect barbs  134 ,  136  toward one another upon assembly (cf. FIG.  18 ). 
     FIGS. 12 and 13 show the manner in which needle protection sleeve  46  has been displaced distally in the direction of an arrow  140  relative to housing  50 , so that the patient can now grasp the sterile needle cover cap  120  through recesses  128 ,  130  and pull it off needle  18  in the direction of arrows  122  in order to prepare for an injection. 
     FIG. 14 shows needle  18  after it has been inserted into subcutaneous fatty tissue  150  of the patient. This position corresponds to the position depicted in FIG. 4 (before injection of the liquid), and is identical to the position depicted in FIG. 5 (after injection of the liquid). The difference between the two figures is the position of piston  22  in cylinder  14 ; this piston is not depicted in FIG.  14 . 
     In FIG. 14, needle protection sleeve  46  once again occupies the position depicted in FIGS. 9 and 10, but its two projections  42 ′,  44 ′ are now located at the upper (i.e. distal) end of grooves  40  and  40 ′, since vessel container  30  has been displaced in the proximal direction upon the insertion of needle  18 . 
     As a result, the distal end position of needle protection sleeve  46  has thus correspondingly changed, as has its proximal end position, which has migrated farther down as compared to FIG.  14 . 
     When needle  18  is then pulled out of the subcutaneous fatty tissue as shown in FIG. 15, needle protection sleeve  46  is thus displaced by its compression spring  56  into its new proximal end position, which is depicted in FIG.  15  and in which it completely encloses needle  18  in order to prevent any danger of injury. 
     In the position shown in FIG. 15, needle protection sleeve  46  is permanently snap-locked in place so that it cannot inadvertently be slid back against the force of compression spring  56 , the result of which would be that someone could be injured or infected by needle  18 . This is accomplished by way of the two detent hooks  134 ,  136  of apparatus  132 , which is depicted in perspective in FIG.  11 . Associated with these detent hooks in housing portion  50  on its inner side is a longitudinal groove  154  which is narrow in its distal region  156  so that detent hooks  134 ,  136  are compressed there, as depicted in FIG.  18 . 
     As depicted in FIG. 19, when device  10  is in the position shown in FIG. 15, detent hooks  134 ,  136  arrive in a wider region  158  at the proximal end of groove  154  and thus snap into place at transition point  160 . This corresponds to the position of the injector shown in FIG. 15, in which needle protection sleeve  46  is permanently snap-locked into its new proximal end position which has thus also become the (final) distal end position when the injection device, after use, has become waste. 
     With the exception of springs  56  and  94 , the parts of injection device  10  are preferably made of plastic, for example of ABS (acrylonitrile-butadiene-styrene polymer), PC (polycarbonate), or POM (polyoxymethylene). 
     Preferred materials are: 
     Housing portions  50 ,  60 , needle protection housing  46 , ejection member  92 , and displacement member  36 : POM or ABS; Vessel container  30 : POM or PC. 
     The selection of plastics is preferably consistent in order to simplify recycling of the injection device. 
     Many variations and modifications are of course possible in the context of the present invention.