Patent Publication Number: US-9402957-B2

Title: Automatic injection device with delay mechanism including dual functioning biasing member

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains to pharmaceutical injection devices, and, in particular, to an automatic injection device. 
     Patients suffering from a number of different diseases frequently must inject themselves with pharmaceuticals. A variety of devices have been proposed to facilitate these injections. One type of device is an automatic injection device. This type of device, when triggered by a user, automatically inserts into the user a needle of a syringe that prior to triggering was disposed within the device housing, and then automatically injects a dose of medication through that inserted needle. One known type of automatic injection device then automatically advances a shroud to cover the needle when the dose is completed. In another type of automatic injection device having a configuration more desirable to some, and instead of having an advancing shroud, the device will automatically retract the needle into the housing when the dose is completed. One difficulty with designing an automatic injector with a needle retracting feature is ensuring both that the full desired contents of the syringe have been injected and that the syringe needle is properly retracted into the device housing after use. 
     International Publication Number WO 2005/115516 explains in additional detail such design difficulty, and further proposes solutions using a type of delay mechanism involving a highly viscous fluid damping. While perhaps functional, these solutions are not without their own shortcomings, such as the delay mechanism being used to transfer force to the syringe during injection. 
     International Publication Number WO 2008/112472 discloses an automatic injector with delay mechanism which has desirable capabilities but which is of larger diameter than may desirable for some. Further, the number of parts, and the camming motion of the delay mechanism with parts sliding against each other, complicates assembly and operation. 
     Automatic injectors frequently are provided with a lock feature that frustrates device triggering prior to a user having prepared for such triggering. One known way of triggering an automatic injector is for a manually operable button to unlatch prongs of a spring-loaded plunging element of the device, such as by the splaying outward or squeezing inward of such prongs to allow passage of the prongs through one or more openings in the surface to which the prongs releasably latch. Various means to prevent this plunger unlatching from occurring too soon have been employed in the past, but such means are not without their shortcomings, such as due to increasing the device complexity or adding undesirable size to the device. 
     Thus, it would be desirable to provide an automatic injection apparatus that can overcome one or more of these and other shortcomings of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     In one form thereof, the present invention provides a delay mechanism for an automatic injection apparatus having a housing, a needled syringe with a plunger, and at least one biasing element for moving the needled syringe in a first direction within the housing to extend the needle of the syringe beyond the housing and to advance the plunger to force syringe contents through the needle for an injection. The delay mechanism includes a shuttle for the syringe, the shuttle including a first latching element; a follower including a second latching element, the second latching element for cooperating with the first latching element to limit motion of the shuttle relative to the follower in a second direction opposite the first direction; a locking member movable within the housing from a locking position to a release position by engagement with the syringe plunger during an injection, the locking member, when in the locking position, preventing rotation of the follower relative to the shuttle, the locking member, when in the release position, allowing rotation of the follower relative to the shuttle; a damping compound between the follower and a supporting surface to dampen rotation of the follower relative to the shuttle; and a dual functioning biasing member acting between the shuttle and the follower, the biasing member providing both a torsional force urging the follower to rotate relative to the shuttle and an axial force urging the shuttle away from the follower; whereby when the locking member moves to the release position during an injection, the dual functioning biasing member first forces the follower to rotate relative to the shuttle from a latching position, at which the first and second latching elements cooperate, to an unlatching position, at which the second latching element is disengaged from the first latching element, and then the dual functioning biasing member forces the shuttle axially relative to the follower to move the shuttle for retracting the syringe needle into the housing after injection. 
     One advantage of the present invention is that a delay mechanism may be provided for an automatic injection which allows a timely retraction of the needle without a release from or overcoming of the driving spring of the syringe, and which is not substantially involved with operational forces applied to the syringe during needle insertion and then injection. 
     Another advantage of the present invention is that an automatic injection device may be provided with a slim profile. 
     Another advantage of the present invention is that an automatic injection device, and such as a delay mechanism therein, may be provided using a reduced number of parts while still having a reliable staging of device operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other advantages and objects of this invention, and the manner of attaining them, will become more apparent, and the invention itself will be better understood, by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a side view of an automatic injection apparatus with delay mechanism of the present invention; 
         FIG. 2  is a longitudinal cross-sectional view of the automatic injection apparatus of  FIG. 1 ; 
         FIGS. 3 a  and 3 b    are respectively perspective and longitudinal cross-sectional views of a main housing body of the apparatus of  FIG. 1  shown separate from the other apparatus components; 
         FIGS. 4 a , 4 b  and 4 c    are respectively perspective, bottom perspective, and longitudinal cross-sectional views of a housing baseplate of the apparatus of  FIG. 1  shown separate from the other apparatus components; 
         FIGS. 5 a , 5 b , 5 c  and 5 d    are respectively perspective, bottom perspective, top and longitudinal cross-sectional views of a housing safety sleeve of the apparatus of  FIG. 1  shown separate from the other apparatus components; 
         FIGS. 6 a , 6 b , 6 c , 6 d  and 6 e    are respectively perspective, side, first longitudinal cross-sectional, bottom perspective and second longitudinal cross-sectional views of a button shown separate from the other apparatus components; 
         FIGS. 7 a , 7 b , 7 c , and 7 d    are respectively two perspective, side and top views of a plunger element shown separate from the other apparatus components; 
         FIGS. 8 a , 8 b  and 8 c    are respectively perspective, bottom perspective and top views of a syringe carriage shown separate from the other apparatus components; 
         FIG. 8 d    is a top view similar to that of  FIG. 8 c    but prior to the syringe carriage being overmolded; 
         FIGS. 9 a , 9 b , 9 c , 9 d  and 9 e    are respectively perspective, first side, second side, longitudinal cross-sectional, and bottom perspective views of an upper shuttle part shown separate from the other apparatus components; 
         FIGS. 10 a , 10 b , 10 c , 10 d  and 10 e    are respectively perspective, first side, second side, longitudinal cross-sectional, and bottom views of a lower shuttle part shown separate from the other apparatus components; 
         FIGS. 11 a , 11 b , 11 c , 11 d  and 11 e    are respectively first perspective, first side, second perspective, second side and longitudinal cross-sectional views of a follower shown separate from the other apparatus components; 
         FIGS. 12 a , 12 b  and 12 c    are respectively perspective, side and top views of a dual functioning biasing member in an unstressed or not preloaded state shown separate from the other apparatus components; 
         FIGS. 13 a , 13 b , 13 c  and 13 d    are respectively perspective, side, longitudinal cross-sectional and top views of a grease collar shown separate from the other apparatus components; and 
         FIGS. 14-19  are longitudinal cross-sectional views of the automatic injection apparatus of  FIG. 1  at subsequent stages of its operation. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent an embodiment of the present invention, the drawings are not necessarily to scale, and certain features may be exaggerated or omitted in some of the drawings in order to better illustrate and explain the present invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1 and 2 , there are shown different views of a first embodiment of an automatic injection apparatus with a delay mechanism of the present invention. 
     The automatic injection apparatus, generally designated  20 , has a trigger that when actuated by a user results in the needled syringe of the apparatus automatically being driven downward such that the injection needle projects beyond the bottom end of the apparatus housing to penetrate the user. The apparatus then proceeds to inject automatically the medication contents of the syringe through the needle, after which the syringe is retracted automatically such that the injection needle is returned to within the housing. The delay mechanism of the apparatus helps to stage the operation to ensure that the medication contents are properly delivered prior to the needled syringe being retracted. 
     It will be appreciated from the following description that apparatus  20  is conceptually similar in various aspects to the devices disclosed in International Publication Number WO 2008/112472, which publication is incorporated herein in its entirety. 
     Apparatus  20  includes an outer housing  22  in which are operationally disposed working components of the apparatus. At the top or distal end of the housing and protruding axially therefrom, a safety-controlled button  25  that is part of the user-operated trigger is provided. When the safety sleeve  26  of the housing is disposed in a proper angular orientation relative to the housing body  24  as rotatably adjusted by the user, button  25  is unlocked and can be depressed to start the automatic injection function of the apparatus. As used herein, distal and proximal refer to axial locations relative to an injection site when the apparatus is oriented for use at such site, whereby, for example, proximal end of the housing refers to the housing end that is closest to such injection site. 
     As further shown in  FIGS. 3 a  and 3 b   , a tubular main body  24  of housing  22  extends between a proximal end  32  and a distal end  34  and is formed from a transparent plastic material, such as ABS plastic. Near the main body distal end, a circumferential or annular snap ring  36  projects inwardly from the housing body interior surface. A longitudinally extending rib  38  for guiding the syringe shuttle projects from the body interior surface proximally of snap ring  36 . Near a middle length portion of body  24 , a pair of angularly spaced ledges or ribs  40  is formed on the body interior surface for supporting the grease or damping collar  300 . An axially extending spline  42  formed on the housing interior surface above one of the ledges  40  serves to rotatably fix collar  300  within the housing. A set of circumferentially spaced retention snaps or ribs  44  angularly offset from ledges  40  and located distally thereof serve to axially locate the follower  250 . 
     The housing  22  of the shown apparatus  20  also includes a baseplate  50 , further shown in  FIGS. 4 a , 4 b  and 4 c   , and an upper body  26  that serves as the safety sleeve, further shown in  FIGS. 5 a , 5 b , 5 c  and 5 d   . Baseplate  50  is made of the same material as housing main body  24  and includes a generally trilobular bottom portion  51  that is keyed to fit within the complementarily shaped-opening at the proximal end  32  of housing body  24  where it is fixedly secured during manufacture, such as via ultrasonic welding. A central aperture  52  of baseplate portion  51  through which a syringe needle moves out from and then back into the housing during use is ringed by a tube portion  54  that distally extends from portion  51 . An interior surface  55  of tube portion  54 , which starting at the tube distal end slopes inward as it extends proximally, includes a circumferential shoulder  56  that aids in centering the syringe. A set of three arcuate slots  58  are formed through portion  51  and are flanked by snaps  59  on the distal face of baseplate portion  51 . 
     A syringe overcap  320 , shown in  FIG. 2 , is made of plastic such as polypropylene SR549M, and includes a base  322  with a knurled periphery  323 . A series or three arcuate cams  325  are in registry with slots  58  and include outwardly facing detents  326  that engage baseplate snaps  59  for a releasable interconnection. A tubular collar  328 , upstanding from base  322 , is adapted to engage a needle shielding assembly  330  that maintains the needle sterility and which is removed from the needle when the overcap is removed from housing  22 . 
     The housing upper body  26  is a sleeve made of a plastic material, such as Lustran ABS 348 that is opaque. A manually grippable main body portion  62  transitions to a reduced diameter portion  64  that fits within the upper portion of housing main body  24 . A circumferential groove  66  in the outer cylindrical periphery of sleeve portion  64  receives housing snap ring  36  during device assembly to allow rotational motion but to prevent axial motion between upper body  26  and main body  24 . Opposed notches  68  are formed in the proximal edge of sleeve portion  64 . One of the notches  68  accommodates the distal end of housing key  38  to limit the extent of locking sleeve rotation. An opening  70  through sleeve portion  64  forms a lock ledge  71  for shuttle capture. A raised indicator  73  formed on the outer periphery of body portion  62  provides a visual notice function in conjunction with lock and unlock icons shown at  76  in  FIG. 1  provided on a label  75  adhered around the housing main body  24 . Indicator  73  aligns with icons  76  when the sleeve  26  is rotationally disposed at end angular positions allowed by the abutment with key  38  of the sleeve stops defined by the notch  68 . 
     The interior surface  78  of housing upper body  26  includes a set of three equally angularly spaced and inwardly projecting snap bumps  80  for engagement with the device button  25 . A projecting, axially extending rib  82  formed on surface  78  fits within a button slot. 
     Button  25  is made of a sturdy yet suitably resilient material, such as Lustran ABS 348, and is further shown in  FIGS. 6 a , 6 b , 6 c , 6 d  and 6 e   . Button  25  includes an end disc  88  with a skirt  90  extending proximally from its outer periphery. End disc  88  has a distal face upon which a force can be directly applied by a user to selectively plunge the button to trigger the apparatus. A notch  92  formed in skirt  90  at its proximal end extends axially and forms a slot which receives rib  82  of housing body  26  so as to rotatably key together the button  25  and body  26 . A set of three equally angularly spaced resilient fingers  94  each provided with a detent bump  95  on its radially inward face are provided at the base of skirt  90 . Each finger  94  is adjacent to one of three equally angularly spaced fingers  97  with inwardly angled stops  98  also provided in skirt  90 . Fingers  94  with bumps  95  cooperate with features on the shuttle to help rotationally locate button  25  on the shuttle, and fingers  97  with stops  98  cooperate with features on the shuttle to attach button  25  to the shuttle and help stage device operation. 
     Depending from the underside of disc  88  to a height above the proximal tips of fingers  94  and  97  is an activating element  100  of the button that is generally tube shaped. The interior surface of button element  100  at its proximal end is chamfered to form a camming surface  102 . A pair of diametrically opposed notches  104  in the proximal end of element  100  serves as clearance slots. 
     Skirt  90  is formed with openings therethrough that define a multitude of resilient snaps or latches  106  that are used to secure the button  25  relative to housing upper body  26  after button plunging. Three such angularly spaced latches  106  are shown. Detents  107  formed in the outer periphery of skirt  90  proximally of each latch  106  facilitate manufacturing assembly. 
     As shown in  FIG. 2 , a medication-filled syringe, generally designated  110 , is mounted within apparatus  20 . Syringe  110  is shown as including a barrel  112 , such as made of glass or other suitable material, with an injection needle  114  mounted at its proximal end which is in fluid communication with the medication contents of the syringe barrel and initially covered by a needle shielding assembly  330 . The plunger mechanism of the syringe is formed in two parts by a plunger element, generally designated  116 , and an elastomeric sealing member or piston  118  that seals the medication within barrel  112 . The shown barrel  112 , needle  114 , needle shielding assembly  330  and piston  118  are of conventional design, but may be differently configured while still providing suitable functionality. For example, a flexible needle shield without a rigid needle shield may be possible, with suitable adaptations for the apparatus, such as to provide engagement of the flexible shield by the overcap. 
     Plunger element  116  is molded of a lightweight but sturdy and sufficiently resilient material, such as Delrin® 311DP from Dupont Engineering Polymers. As further shown in  FIGS. 7 a , 7 b , 7 c  and 7 d   , plunger element  116  includes a proximal region  120  with a disc-shaped foot  121  at one end that serves to operationally abut sealing piston  118  during plunger advancement, and a disc-shaped flange  123  at the other end. A middle region  124  of the plunger element that extends axially upward from flange  123  includes an axially extending recess or cutaway  125  that further exposes an upper surface  126  of flange  123  which serves as a syringe carrier ledge. A disc-shaped flange  128  with a larger diameter than flange  123  is formed at the upper end of plunger middle region  124 . A depending bar or outrigger  130  that during an injection directly engages a locking member to unlock the follower of the apparatus delay mechanism is formed on the outer radial periphery of flange  128 . Unlocking bar  130  extends axially and proximally from flange  128  in spaced relationship with plunger middle region  124 . 
     The distal region of plunger element  116  includes a pair of resilient prongs, generally designated  134 , adapted to latchably engage a shuttle of the apparatus until released by the apparatus triggering mechanism for the shown embodiment. Each prong  134  includes an upstanding leg  136  that projects distally from a more central portion of flange  128  with an axially-aligned space or gap  137  between legs  136 . At the distal end of its leg  136  each prong  134  includes a latch feature having a latching surface  138 , an outward tip  139  at an outer extent of latching surface  138 , and a ramp surface  141 . Latching surface  138  extends generally radially outward from leg  136  and faces proximally. Latching surface  138  is formed with a slight undercut so as to slope slightly proximally from leg  136  to tip  139 . Ramp surface  141  extends distally and at an angle inward from the tip  139  to form an outward facing ramp used in the inward camming of the prongs for release as described below. Each ramp surface  141 , near its radially outer area and along a middle circumferential portion thereof, is interrupted by a locking protuberance  143  integrally formed therewith that projects distally toward button  25 . Locking protuberance  143  extends upward the same extent as ramp surface  141  such that the upward tips of the locking protuberances  143  are disposed at the same height as the upward tips of the ramp surfaces  141 . The upward tips of locking protuberances  143  are disposed radially outward of the upward tips of the ramp surfaces  141 . The radially outwardly facing surfaces  146  of the upward tips of locking protuberances  143  are rounded to facilitate insertion through spring  149  during apparatus assembly. 
     Locking protuberance  143  and ramp surface  141  are in spaced relationship in that they define a radial space therebetween. A V-shaped opening  145  that the radial space forms between ramp surface  141  and the inward face of locking protuberance  143  is shaped and sized to receive the proximal end of button element  100 . 
     An axially extending boss  147  formed on each leg  136  is provided to aid in centering the drive coil spring  149  shown in  FIG. 2 . The proximal end of spring  149 , as centered by dogs  150  on flange  128 , seats and acts against flange  128 , and the distal end of spring  149  acts against the shuttle. 
     An overmolded syringe carrier further shown in  FIGS. 8 a , 8 b , 8 c  and 8 d    is generally designated  155  and fits to a keyed flange  111  of syringe barrel  112  to be rotatably fixed together. Syringe carrier  155  includes a base formed of a rigid material, such as DCL4036 20% carbon filled polycarbonate, which base includes a generally C-shaped section  157  from which upwardly projects a support  158  with a radially inwardly protruding clip  159 . A protrusion  160  is formed in the top of clip  159  and is used to facilitate the overmolding process. A softer overmolding  162  that fully covers the legs of base section  157  provides a cushioning for the glass syringe held by the carrier to reduce the likelihood of breakage. A suitable overmolding is made of an injection moldable thermoplastic elastomer. When apparatus  20  is fully assembled, syringe barrel  112  snugly fits within central opening  164  with syringe flange  111  captured axially between overmolding  162  and the underside of clip  159 , and with the underside of the tip region of clip  159  facing for direct supportive engagement the upper surface  126  of plunger flange  123 . This supportive engagement of the syringe carrier clip  159  by surface  126  prevents the syringe  110  held within carrier  155  from moving outward of the housing  22  before apparatus use. 
     The delay mechanism of apparatus  20  includes a shuttle, generally designated  170 , a follower  250  that releasably latches with the shuttle  170 , and a dual functioning biasing member  290  acting between the shuttle and the follower. In the shown embodiment, shuttle  170  is formed of an upper shuttle  172  and a lower shuttle  174  further shown in  FIGS. 9 a , 9 b , 9 c , 9 d  and 9 e    and  FIGS. 10 a , 10 b , 10 c , 10 d  and 10 e   , respectively. Shuttle parts  172  and  174  are fixedly connected during manufacturing assembly, such as with the described snap fit or other suitable connection manner, to together serve as the shuttle. The multi-piece construction facilitates molding and assembly of the shuttle, as well as the assembly of the apparatus components within the interior hollow  175  of the shuttle. One suitable material for shuttle part  172  is a plastic such as EXL1992T Polycarbonate alloy that is transparent, and one suitable material for shuttle part  174  is a polycarbonate such as Makrolon 2458 that is transparent. 
     The bottom portion  176  of upper shuttle  172  includes a protruding alignment block or key  178  that closely fits within a notch  222  formed in the distal end  223  of the body  220  of lower shuttle  174 . During manufacturing assembly of the mating shuttle parts, radially protruding and partially circumferentially extending lips  180  provided on opposite sides of upper shuttle  172  snap lock over ledges  225  defined by windows  226  formed in lower shuttle  174 . A pair of keys  182  projecting from the periphery of upper shuttle  172 , one of each key  182  above each lip  180 , fits into smaller notches  228  formed in the distal end  223  of shuttle body  220 . The fitting of keys  182  within notches  228  and alignment block  178  within notch  222  rotatably fixes the shuttle parts together when connected. 
     The bottom portion  176  of upper shuttle  172  above block  178  includes an opening  184  from which a locking flexure  186  outwardly extends at an angle. Flexure  186  cooperates with the lock ledge  71  of the housing to secure the shuttle in a retracted position after use. On the side of shuttle  172  opposite of opening  184 , an opening or slot  188  extending to the bottom of the upper shuttle is provided which accommodates plunger outrigger  130 . Ribs  189  formed in the inner surface of bottom portion  176  serve as stops for abutment by syringe flange  111  to limit distal movement of the syringe  110  during assembly. 
     The upper portion of upper shuttle  172  is a tubular, cylindrical body  190  with an overhanging cap portion  192 . A central aperture  194  through cap portion  192  allows passage of the latching portion of plunger prongs  134 . A pair of dogs  196  that project distally from the top surface of cap portion  192  are diametrically opposed around aperture  194  and help guide activating element  100  of button  25  into aperture  194  during use. The prong-engaging surfaces  195  between dogs  196  include a ramping upward surface adjacent to aperture  194  that is complementary to the undercut of latching surfaces  138  to provide a more secure but releasable connection therebetween. A collar  198  depending from the underside  199  of cap portion  192  within hollow  175  centers the distal end of spring  149  that acts directly against underside  199 . Two opposing cut outs  200  in collar  198  allow passage of locking protrusions  143  of prongs  134  and aid assembly by presenting a ramp surface that deflects the prongs inward during assembly. 
     The outer radial periphery of cap portion  192  includes three beveled sections  202  and three land sections  203  in alternating arrangement around the shuttle circumference. The angular ends of each land section  203  are defined by grooves or indents  205 . Land sections  203  are designed to have detents  95  of button fingers  94  slide therealong during button rotation. Indents  205  cooperate with detents  95  to aid in keeping the button in one of two preferred angular or rotational positions relative to the shuttle  170 , but which detent connections can be readily overcome when the button is moved between such positions by manual rotation of the sleeve  26 . The interaction between indents  205  and detents  95  also provides a tactile and audible indication of when the button rotation has reached an end point. 
     Three stop ribs, generally designated  204 , project from the periphery of shuttle body  190  proximally of the three cap beveled sections  202 . Each stop rib includes a circumferentially extending segment  206 , an upstanding axially extending segment  208  at one end of segment  206 , and a depending axially extending segment  210  with an angled lead-in  211  at the other end of segment  206 . Three axially extending stop ribs  214  are provided proximally of the three land sections  203 . 
     During manufacturing assembly, button  25  is mounted to shuttle  170  by moving the parts axially together such that button fingers  97  with stops  98  slide and snap fit over cap beveled sections  202 , at which point distal removal of the button is resisted by stops  98  abutting the overhanging lip of the beveled sections  202  of cap portion  192 . When button  25  is so mounted, rib segments  206  serve as axial stops for button stops  98  to abut and thereby frustrate manual button plunging when the button is not in an unlocked state. Rib segments  208  work with stops  98  to further prevent button  25  from being rotated in the wrong direction from a locked state, and stop ribs  214  prevent button  25  from being rotated too far during unlocking. Rib segments  210  and stop ribs  214  guide the downward travel of the button during its plunging, and the longer rib segment  210  shown in  FIG. 9 c    serves as an abutment for a stop  98  to prevent manual relocking of the sleeve  26  during fluid delivery. 
     Lower shuttle  174  is generally tubular with a cylindrical body  220  that steps down via a substantially annular, radially aligned flange  221  to a reduced diameter, cylindrical proximal region  230  that fits within follower  250 . Flange  221  is interrupted by an upstanding rib region  247 . Flange  221  serves as the support that directly engages the syringe carrier  155  for effectively engaging and carrying the syringe upward to withdraw the syringe needle after injection. A bar  238  that extends distally from distal end  223  is used to rotatably lock housing sleeve  26  after an injection by fitting within a notch  68 . At its proximal end, shuttle  174  includes an annular lip  233  that extends radially inward to define the opening through which extends syringe barrel  112 . An annular recess provided around the end of proximal region  230  outward of lip  233  forms a shoulder  231  that seats and centers the biasing member  290  described below that acts on the shuttle. An axially extending groove  232  in lower shuttle body  220  receives housing key  38  to rotatably fix shuttle  170  with housing  22  along the entire axial travel of the shuttle therein. 
     The shuttle includes at least one latching element for releasably engaging the follower of the delay mechanism. The latching element is shown provided as a set of tabs  234  and  236  that are angularly spaced around and radially outwardly project from proximal region  230  near its proximal end. Tabs  234  and  236  are shown as differently sized, block-shaped projections that serve as latching hooks to engage the follower. 
     An axially oriented notch  240  that opens radially outward is formed through tab  234  and into shoulder  231 . Notch  240  is sized and configured to receive an upper projection  294  of the biasing member. As shown in  FIG. 10 e   , notch  240  includes a circumferential jog at its inward depth that results in tab  234  providing a pocket  235  for radially retaining the biasing member upper projection. 
     At the proximal end of lower shuttle body  220  on its outer periphery, an angled, locking latch surface  242  is formed therein. Latch surface  242  is disposed proximally of and angularly adjacent to an opening  244  formed in the upward protruding rib region  247 . Opening  244  is disposed in line with an axially extending channel  246  formed in the interior surface of lower shuttle body  220  along its entire height. The edges of rib region  247  defining opening  244  are sloped to help lead outrigger  130  into the opening. Channel  246  accommodates plunger outrigger  130  to loosely rotatably key shuttle  170  and plunger element  116  while allowing axial motion of the plunger element  116  relative to the shuttle such that the proximal tip of outrigger  130  can project through opening  244  to unlock the locking mechanism described below. 
     The delay mechanism follower  250  is further shown in  FIGS. 11 a , 11 b , 11 c , 11 d  and 11 e   . Follower  250  is formed of a rigid yet sufficiently resilient material to integrally provide the locking member feature. One suitable material for the shown follower  250  is Delring® 311DP. Follower  250  includes an upper portion  252  that fits concentrically around shuttle proximal region  230 . Two partially circumferentially extending ledges  254  and  256  are formed in follower portion  252  and serve as latching elements that engage shuttle latching tabs  234  and  236 . Ledge  254  is formed by a window  258  through follower portion  252  and opens at one angular end to an axially extending channel  260  formed in the interior surface of follower portion  252 . Ledge  256  in part opens to window  261  and at one angular end opens to an opening  262  in follower portion  252 . Channel  260  and opening  262  allow axial movement of tabs  234  and  236  therein for manufacturing assembly and for shuttle release relative to the follower during apparatus use. Opening  262  tapers at  264  to a slot-shaped portion  266  adapted to closely receive a radial projection  296  of the biasing member. 
     Near the base of follower portion  252 , a flange  268  that extends around the majority of the circumference projects radially outward from follow portion  252 . Flange  268  snaps past housing snaps  44  during apparatus assembly. The interior surface of follower portion  252  includes an inwardly projecting ring  270  provided with three equally angularly spaced ribs  272  on its upper face. Ring  270  defines an opening through which the syringe barrel extends and provides a seat for the biasing member that is centered by ribs  272   
     A sleeve shaped lower portion  274  of follower  250  depends from follower portion  252  and has a lesser diameter. Four slots  276  in the proximal edge of portion  274  define four damping fins  278  of the follower. 
     A locking member for follower  250  to limit its rotation relative to the shuttle  170  is integrally formed with follower  250 . In alternate embodiments, differently configured locking members, including being a separate piece or being formed with the shuttle, may be employed. The locking member is generally designated  280  and is formed as a flexure arm  282  with an upwardly extending latch  284  at its end. Flexure arm  282  extends in a generally circumferential direction from follower upper portion  252 . As flexure arm  282  occupies a similar annular space as follower portion  252 , and because arm  282  is designed to be bent axially to cause latch  284  to be moved axially relative to the shuttle in order to unlock the follower for rotation, an axial space  286  between arm  282  and the area of the follower portion above window  261  is provided to accommodate arm bending. Such space would not be required if, for example, the latch was unlocked via a radial movement thereof. 
     The dual functionality of biasing member  290  results from it providing a torsional force and an axial force during use, both of which forces act directly between follower  250  and shuttle  170 . For the configuration shown in apparatus  20 , biasing member  290  functions as both a torsion spring and a compression spring, and can be made as a single component that is readily handled during manufacturing assembly. The torsional force and axial force result from a release of a torsional preloading and an axial preloading of the biasing member  290 , which preloading has been accomplished during the manufacturing assembly of apparatus  20 . 
     Biasing member  290  is shown as a cylindrical spring formed of a helically coiled wire  292 . One suitable such spring is made of 302 stainless steel with a wire diameter of 0.024 inch. Spring  290  is selected to provide suitable torsional and axial forces within the available space, and the selection is dependent upon the device operation, such as the delay required, and the design of the cooperating components, such as the damping compound and follower and grease cup configurations. Other designs of biasing members, such as a metal or plastic flexure configured to perform the dual functions, may be substituted for the single metal coil spring shown. 
     The internal opening  295  of spring  290  freely receives lower shuttle proximal region  230 , while the outer diameter of spring  290  freely fits within follower upper portion  252 . The distal end coil  293  of wire  292  which abuts the shuttle shoulder  231  terminates with a protruding end or tip  294  that projects distally. Tip  294  is disposed within the cross-sectional area of the cylindrical coil as shown in  FIG. 12 c   . Tip  294  is sized and shaped to fit within shuttle pocket  235  to engage shuttle  170 . The proximal end coil  297  of wire  292  which abuts the follower ring  270  terminates with a radially outwardly protruding tip  296 . Tip  296  extends beyond the cross-sectional area of the cylindrical coil. Tip  296  is sized and shaped to closely fit within opening portion  266  to engage follower  250 . 
     During manufacturing assembly of apparatus  20 , with spring  290  arranged so that tips  294  and  296  respectively fit within pocket  235  and opening  266  of the spaced follower  250  and lower shuttle  174 , spring  290  is preloaded both axially and torsionally between follower  250  and shuttle lower portion  174  as the follower and shuttle lower portion are brought together axially and rotated so as to be latched, via the interaction of ledges  254 ,  256  and tabs  234 ,  236 , and then so locked, via the interaction of locking member  280  and shuttle surface  242 . 
     A grease cup or collar, generally designated  300 , is further shown in  FIGS. 13 a , 13 b , 13 c  and 13 d   . Cup  300  provides a support surface for the damping fluid as the follower  250  rotates relative to that support surface. In an alternate embodiment, the support surface can be otherwise provided, such as being integrally formed with the housing body. Cup  300  is made from a plastic material, such as ABS TR-558A1 from LG Chemical Ltd, that is transparent. Cup  300  includes an annular body  302  that has a generally cylindrical outer periphery, and a round central aperture  303  through which fits the syringe barrel. Cup  300  is axially supported within housing  22  by ledges  40 . Ribs  304  define a keying slot  305  on the outer periphery. Two slots  305  are shown, but only one is needed to fit over the housing spline  42  that rotatably fixes cup  300  and housing  22 , and the other slot makes initial orientation less critical during assembly as well as typically allows passage over key  38  during assembly. Cup body  302  includes a generally U-shaped wall portion  308  that defines an annular hollow or channel  307 . Enlarged areas  309  that open into the top of hollow  307  are so sized to better accommodate the nozzles by which the damping compound is inserted into the hollow  307 . 
     A damping compound or fluid  315 , such as a silicone grease thickened with Teflon available from Nye Lubricants as Nye fluorocarbon gel 880, fills annular hollow  307 . Follower fins  278  fit within hollow  307  such that compound  315  is disposed both radially inward and outward of such fins  278 , as well as between adjacent fins  278  and as a film between the fin undersides and the base of the follower wall, resulting in a damping or delay effect as the follower fins  278  try to rotate relative to the U-shaped interior surface of wall portion  308  with the viscous damping fluid providing a resistance to this rotation during operation. Other compounds with different properties may be selected by one of skill in the art in view of the delay selected by the manufacturer to be provided by the delay mechanism, and in view of modifications that may be made by the skilled artisan to the placement of the compound as well as other aspects of the delay mechanism, such as the spring-generated torsional force and the size and shape of the follower and the grease collar. 
     The construction of apparatus  20  will be further understood in view of a description of its operation. With the apparatus initially configured in a locked state as shown in  FIGS. 1 and 2 , the apparatus cannot be triggered. If a user applies a plunging force on button  25 , the button stops  98  axially abut shuttle rib segments  206 . Furthermore, due to button activating element  100  extending within V-shaped opening  145  but with clearance slots  104  being rotationally out of alignment from locking protuberances  143 , the protuberances  143  will abut the outer periphery of element  100  and prevent inward movement of prongs  134  sufficient for disengagement from the shuttle. 
     The syringe overcap  320  is then manually removed by the user overcoming the engagement of overcap detents  326  with snaps  59  and pulling the overcap proximally off of the housing to also remove the needle shielding assembly  330 . This overcap removal is facilitated by the user twisting the overcap relative to the housing, which twisting, due to the camming effect of cams  325  against plate  51 , shifts the overcap proximally. The engagement of the syringe carrier clip  159  with plunger flange surface  126  limits proximal motion of syringe  110 . After overcap removal, apparatus  20  is arranged as shown in  FIG. 14 . 
     To allow for an injection, the locking or safety that prevents triggering needs to be unlocked. This unlocking can be done before or after the apparatus  20  is oriented at the injection site. The user can grip and manually rotate locking sleeve  26  relative to the housing main body  24  until the alignment indicator  73  is in registry with the unlock icon of icons  76 , at which the edge of sleeve notch  68  abuts housing key  38 . This rotation of sleeve  26  rotates button  25  due to the keyed connection therebetween. Besides the visible icon, the unlocked registration or state also will be indicated by the button finger detents  95  snapping into the indents  205  at the opposite ends of the land sections  203  at which the button detents were initially located in  FIG. 14 . At this point, button stops  98  have been moved angularly clear of shuttle rib segments  206 , and clearance slots  104  are now rotationally aligned with protuberances  143 , and apparatus  20  is arranged as shown in  FIG. 15  and prepared for an injection. 
     In this prepared state, and with the apparatus positioned at an injection site, when a user applies a plunging or downforce on button  25 , button  25  starts to move into housing sleeve  26  as activating element  100  engages prong ramp surfaces  141 . As button  25  moves further, prong legs  136  bend inward, reducing gap  137 , due to the camming inward of the ramp surfaces by the button element  100 . Locking protuberances  143  fit through clearance slots  104  so as to not prevent this prong inward motion. When prongs  134  have been bent inward sufficiently to disengage latching surfaces  138  from shuttle surfaces  195 , at which point the plunger prongs can fit through the shuttle opening  194  as shown in  FIG. 16 , the drive spring  149  directly biases the plunger element  116  downward to drive it and thereby piston  118  proximally, which driven motion shifts syringe barrel  112  proximally relative to the shuttle and the housing  22  to cause the tip of needle  114  to project beyond housing proximal end for penetrating a user&#39;s skin, and then forces the medication contents of the syringe through that needle for an injection. In  FIG. 16 , the button  25  is shown at the end of its plunging, at which arrangement sleeve rib  82  reaches the end of button slot  92 , and button latches  106  have snap fit under sleeve snap bumps  80  to hold the button in its plunged condition relative to the housing, and with button end disc  88  flush with the top edge of sleeve  26  so as to visually indicate apparatus use. In  FIG. 16 , the plunger element is shown unlatched from the shuttle but before the spring  149  has largely uncoiled to drive the plunger element downward. 
     As plunger element  116  moves proximally during medication injection, the outrigger  130  of the plunger element, as shown in  FIG. 17 , slides within shuttle slot  188  and then channel  246  until the proximal tip of outrigger  130  enters opening  244  and abuts and unlocks locking member  280 . In particular, the outrigger  130  abuts an upper face of latch  284  and shifts latch  284  axially, by bending flexure  282  to close the gap  286 , which axially shifting unlatches latch  284  from shuttle latching surface  242  so as to unlock the follower  250  for rotation. This unlocking typically will be designed to occur shortly before the end of proximal travel of the plunger mechanism. 
     When locking member  280  is so unlocked or released, the follower  250 , as urged by the torsional preloading of biasing member  290 , rotates within the housing  24  and around the rotatably fixed shuttle  170 . The viscous damping compound  315  between the follower fins  278  and cup wall portion  308  dampens or offers a resisting force to this follower rotation, which resistance results in a passage of time before shuttle unlatching, during which time remaining medication can be properly expelled from the syringe through the needle. Rotation of follower  250  about shuttle  170  is driven by spring  290  until follower opening  262  and channel  260  align with shuttle tabs  236  and  234 , respectively. In this arrangement, at which apparatus  20  is shown in  FIG. 18 , tabs  234  and  236  are clear of ledges  254  and  256  such that shuttle  170  and follower  250  are unlatched. 
     When shuttle  170  and follower  250  are so unlatched, the shuttle  170 , as urged by the compressive preloading of biasing member  290 , translates distally within the housing  24  until distal end  223  of lower shuttle  174  meets the proximal end  69  of body  26 . As shuttle  170  is retracted, the needled syringe  110  is carried by the shuttle distally so as to retract the proximal tip of the injection needle  114  to a protected position within the housing  24 . The shuttle is held in this retracted position by the axial force of the biasing member  290  and is locked in this retracted position by the snap fitting of shuttle locking flexure  186  within opening  70  against ledge  71 . Attempts by the user to rotate sleeve  26  relative to housing  24  is frustrated by the presence of bar  238  within a notch  68 . At this point, the apparatus is configured as in  FIG. 19 , and the user then can dispose or otherwise handle the apparatus in the normal course. 
     Apparatus  20  is designed to facilitate its manufacturing assembly. For example, a subassembly of lower shuttle  174 , spring  290 , follower  250 , and damping collar  300  with damping compound  315  can be snap fit into a housing subassembly of main body  24  and baseplate  50 . Another assembly process can involve placing a syringe  100  in alignment with a subassembly of upper shuttle  172 , drive spring  149 , plunger element  116 , button  25  and sleeve  26 , snap assembling syringe carrier  155  to the syringe and plunger element, assembling this entire subassembly to the previously assembled lower shuttle assembly and housing, applying a label to the housing, and then securing the overcap  320  to the housing baseplate  50  in engagement with a previously assembled needle shielding assembly  330 . 
     While this invention has been shown and described as having preferred designs, the present invention may be modified within the spirit and scope of this disclosure. For example, differently configured releasable locking members may be used to keep the syringe and follower rotationally fixed despite the torsional force applied by the biasing member. Furthermore, the shuttle and the associated delay mechanism can be used in apparatuses with different other components, such as alternate trigger locking devices, just as the shown trigger locking device can be used with differently configured automatic syringe moving mechanisms. Still further, the dual functioning biasing member may be configured to work with differently configured components of a delay mechanism, such as a delay mechanism in which the shuttle and follower still have a fluid dampened relative rotation upon unlocking, but where the follower and shuttle do not unlatch after follower rotation but rather move together axially when the follower instead unlatches from the housing, and the dual functioning biasing member acts not directly between the follower and shuttle in such delay mechanism but rather acts between the follower and housing. This application is therefore intended to cover any variations, uses or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.