|Title of Invention||
A MEDICATION DISPENSING APPARATUS
|Abstract||A medication dispensing apparatus (20, 220) comprising: a housing (35); a drive member (60, 280) within said housing ,a fluid container (28) defining a medicine-filled reservoir (30) with a movable piston (32) at one end; a plunger element (90, 260);a gear set (52) including first and second pinions (160, 166); a first rack (84) engaged with said first pinion, a second rack (80) engaged with said second pinion and movable within said housing on a piece (62) clutchably connected to said drive member;said gear set pivotal on said plunger element and shiftable proximally and distally with the plunger element; a latching element (180, 225) including a latching lip (186, 227) and a skid (190, 236);said drive member including an axially extending, skid-engaging surface (71) along which said skid is slidable as said drive member passes distally during advancement during plunger element shifting in the distal direction , said skid-engaging surface shifts distally of said skid such that said skid passes beyond the proximal end upon administration of a final dose allowing said latching lip to be urged by said spring force from said first position to a second position for engagement with said latchable element to physically lock said plunger element to prevent further dose preparing and injecting.|
The present invention relates to a medication dispensing apparatus.
BACKGROUND OF THE INVENTION
The present invention pertains to medication dispensing devices, and, in
particular, to a portable medication dispensing device such as an injector pen.
Patients suffering from a number of different diseases frequently must inject
themselves with medication. To allow a person to conveniently and accurately self-
administer medicine, a variety of devices broadly known as injector pens or
injection pens have been developed. Generally, these pens are equipped with a
cartridge including a piston and containing a multi-dose quantity of liquid
medication. A drive member, extending from within a base of the injector pen and
operably connected with typically more rearward mechanisms of the pen that
control drive member motion, is movable forward to advance the piston in the
cartridge in such a manner to dispense the contained medication from an outlet at
the opposite cartridge end, typically through a needle that penetrates a stopper at
that opposite end. In disposable pens, after a pen has been utilized to exhaust the
supply of medication within the cartridge, the entire pen is discarded by a user, who
then begins using a new replacement pen. In reusable pens, after a pen has been
utilized to exhaust the supply of medication within the cartridge, the pen is
disassembled to allow replacement of the spent cartridge with a fresh cartridge, and
then the pen is reassembled for its subsequent use.
Some injector pens allow a dose to be set that is larger than the amount of
useable medicine remaining in the pen. While some users may find such settability
undesirable, providing an insufficient remaining dose indicator may not be practical
in all cases, such as due to it complicating the pen design. Still further, a
shortcoming with some injector pens is that the design platform on which they are
based may not allow a manufacturer sufficient options as to the mechanical
advantage to provide, such as a mechanical advantage that can be very small in
order to readily inject a large volume dose, or which mechanical advantage can be
quite large so as to deliver a small volume dose with a suitable plunger travel.
Thus, it would be desirable to provide an 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 medication dispensing
apparatus including a housing, a drive member within the housing and movable in a
distal direction, a fluid container defining a medicine-filled reservoir with a movable
piston at one end and an outlet at the other end, the piston being engageable by the drive
member to be advanced toward the outlet a distance equal to a distal movement of the
drive member when the drive member is moved distally, a means for driving the drive
member distally, and a latching element including a latching lip and a skid. The drive
member includes an axially extending, skid-engaging surface along which the skid is
slidable as the drive member passes distally during advancement. The skid-engaging
surface has an axial length and a proximal end, and the drive member along the axial
length is structured and arranged with the skid so as to maintain the latching lip against a
spring force in a first position free of the driving means during dose preparing and
injecting prior to a final dose administration. The skid-engaging surface shifts distally of
the skid such that the skid passes beyond the proximal end upon administration of a final
dose, whereby the latching lip is urged by the spring force from the first position to a
second position to physically lock the driving means to prevent further dose preparing
One advantage of the present invention is that a medication dispensing apparatus
can be provided with an uncomplicated and robust mechanism for automatically locking
the apparatus to prevent further use after a final dose of the apparatus has been
Yet another advantage of the present invention is that a medication dispensing
apparatus can be provided which is readily adaptable by the manufacturer to furnish a
mechanical advantage during dose administration selected from a wide range of such
advantages, such as a small advantage of about two for a large volume dose, up to a large
advantage of about sixteen for a small volume dose.
Another advantage of the present invention is that a medication dispensing
apparatus can be provided which is internally configured to utilize space efficiently to
allow for a compact design that contributes to a small and symmetrical design of the
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 taking in conjunction with the accompanying drawings, wherein:
Fig. 1 is a side view of a first embodiment of a medication dispensing apparatus
of the present invention, which apparatus is arranged in a ready or ready-to-be-cocked
Fig. 2 is a longitudinal cross-sectional view of the medication dispensing
apparatus of Fig. 1;
Fig. 3 is a longitudinal cross-sectional view, taken along line 3-3 of Fig. 1, of the
medication dispensing apparatus of Fig. 1;
Fig. 4 is an exploded, top perspective view of the medication dispensing
apparatus of Fig. 1, wherein an apparatus cap is also shown;
Fig. 5 is a bottom perspective view of the medication dispensing apparatus of Fig.
Fig. 6 is a bottom perspective view of the medication dispensing apparatus of Fig.
1, and with a bottom portion of its housing removed to better show internal components
of the apparatus;
Fig. 7 is a bottom perspective view of the medication dispensing apparatus of Fig.
1, with portions of its housing and larger pinion removed to better show internal
components of the apparatus;
Fig. 8 is a bottom perspective view of the medication dispensing apparatus of Fig.
1 after being manipulated from its ready state to a cocked or ready-to-inject state, with
portions of its housing and larger pinion removed to better show internal components of
Fig. 9 is a top perspective view of the medication dispensing apparatus of Fig. 1,
with a top portion of its housing removed to better show internal components of the
Fig. 10 is a top perspective view of the medication dispensing apparatus of Fig. 1
after being manipulated from its ready state to a ready-to-inject state, with a portion of its
housing removed to better show internal components of the apparatus;
Fig. 11 is a top perspective view of a portion of the apparatus of Fig. 1 after being
manipulated from its ready state to a ready-to-inject state, with portions of its housing
and pinion-engaging piece removed to better show internal components of the apparatus;
Fig. 12 is a perspective view of a housing half showing a guide of a partial-
cocking-preventing mechanism; and
Fig. 13 is an exploded, top perspective view of another embodiment of a
medication dispensing apparatus of the present invention, wherein the apparatus cap is
Corresponding reference characters indicate corresponding parts throughout the
several views. Although the drawings represent embodiments 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
DETAILED DESCRIPTION OF THE INVENTION
Referring now to Figs. 1-12, there is shown a first embodiment of a medication
dispensing apparatus of the present invention. Any directional references in this detailed
description with respect to Fig. 1 or any of the other Figures, such as front, side or back,
or up or down, or top or bottom, are intended for convenience of description, and by
itself does not limit the present invention or any of its components to any particular
positional or spatial orientation.
The apparatus, generally designated 20, is an injector pen of a design that builds
upon the teachings of U.S. Provisional Patent Application 60/557,545, which also was
filed with the United States Receiving Office of the World Intellectual Property
Organization and assigned application number on even date with the
international filing of this application, the entire contents of which are hereby
incorporated by reference. Medication injector pen 20 is a disposable pen that is
repeatedly operable by a user to deliver a fixed dose that is established by the pen
The distal portion 22 of injector pen 20 includes a plastic tubular retainer 24 that
holds a cartridge 28 therein. Cartridge 28 is of conventional design, including a
medicine-filled reservoir 30 sealed at one end by a slidable piston 32 and sealed at the
other end by an injection needle-pierceable septum 33. Retainer 24 is made of a clear
plastic material to allow a user to see the contents of reservoir 30. Threading 26 on the
stepped-down distal end of retainer 24 allow a releaseably mounting of, for example, a
conventional injection needle assembly shown at 25. Pen 20 is shown in Figs. 4 and 5 as
having a protective cap 29 that removably mounts to the cartridge retainer 24 for
protection thereof, which cap has a distal end design at 31 to prevent the capped pen
The proximal portion 34 of injector pen 20 includes a protective external housing
35 that is somewhat elliptical in transverse cross-section. To facilitate assembly of the
apparatus, housing 35 is formed from multiple, interconnected injection molded plastic
pieces. Housing 35 is shown having longitudinal halves 36 and 38 that are
complementarity designed to mate and be fixedly secured together during manufacture,
such as via ultrasonic welding.
The interior surfaces 37 and 39 of housing halves 36 and 38, respectively, are
shown formed with a variety of ribs and bulkheads that serve to maintain the alignment
and guide the motion of the apparatus components disposed within housing 35. Housing
halves 36 and 38 respectively include distally projecting, curved flanges 40 and 42.
During apparatus manufacture, to mount the fluid container to the assembled housing,
flanges 40 and 42 are first inserted within the proximal end of retainer 24 radially
outward of the cartridge body, and then fixedly secured to the retainer, such as via
adhesives or ultrasonic welding. When retainer 24 and housing 35 are so secured,
cartridge 28 is axially sandwiched between the interior surface of retainer 24 and an
internal bulkhead 44 of the housing to prevent axial movement of the cartridge during
Pen proximal portion 34 includes an axially advanceable drive member generally
designated 50, a gear set generally designated 52, and a plunger member generally
Drive member 50 includes a cartridge-engaging piece 60 and a pinion-engaging
piece 62, each injection molded in a single piece from plastic. Cartridge-engaging piece
60 has a square rod-shaped body 64 that extends in the axial direction to a proximal end
65, and a load distributing, disc-shaped portion 66 formed at the distal end of body 64.
Four angularly spaced, contoured gussets 68 span body 64 and disc 66.
Drive member pieces 60 and 62 are constrained by the interior surfaces of
housing halves 36 and 38 to be axially translatable and rotatably fixed within the
housing. Cartridge-engaging piece 60 is movable in the distal direction and prevented
from proximal movement relative to the housing halves, while pinion-engaging piece 62
is clutchably connected to cartridge-engaging piece 60 to be moveable relative thereto in
a proximal direction but not the distal direction. These one-way axial motions are
achieved with ratchets in apparatus 20. In particular, body 64 of cartridge-engaging piece
60 includes a row of one-way ramping ratchet teeth 70 on two opposite sides of its four
sides, which teeth continue uninterrupted along a portion of the axial length of the body.
Ratchet teeth 70 are engaged by a pair of diametrically opposed, resilient tabs or pawls
72 integrally formed with housing half 38. Pawls 72 slide along and over teeth 70 when
drive member piece 60 is advanced distally during use, but abut the transverse, proximal
face of teeth 70 to prevent piece 60 from backing up in the proximal direction.
Proximally of pawls 72, a pair of diametrically opposed resilient pawls 75 of
pinion-engaging piece 62 also engage the same rows of ratchet teeth 70 on opposite sides
of body 64. Pawls 75 slide along and over one or more teeth 70 when pinion-engaging
piece 62 is moved proximally during pen cocking, but abut teeth 70 during the distal
advancement of pinion-engaging piece 62 during injection, which abutting results in
pinion-engaging piece 62 shifting distally the cartridge-engaging piece 60. The pitch or
distance between the transverse face of each adjacent tooth 70 preferably is the distance
piston 32 needs to be advanced to deliver the pen's fixed dose.
In addition to its pawls 75, pinion-engaging piece 62 includes a plate-shaped body
77. A longitudinally extending rack 80 projects from one side of body 77. A pair of
parallel, longitudinally extending ribs 82 project from the opposite side of body 77 and
slidable receive rod-shaped body 64 therebetween. Another set of parallel rib portions 83
are shaped to slide along a ridge 45 formed on the interior surface 39 of housing half 38.
A fixed or axially stationary rack 84 is included within pen proximal portion 24.
Rack 84 is shown intergrally formed with housing half 38.
Plunger member 54 allows a user to control the internal gear set of the apparatus
to prepare pen 20 for injection, as well as to perform the injection. Plunger member 54 is
formed of a multi-piece construction, including an input element 90, a button 92, and a
force limiting biasing member 94.
Button 92 is molded from plastic and externally sized and shaped to be rotatably
fixed while slideable within housing 35. An internal hollow 93 of button 92
accommodates a biasing member 94 axially extending therethrough, and a series of
longitudinally extending, internal ribs 95 of button 92 maintain the alignment of biasing
member 94. The proximal end of button 92 is covered with a softer material shown at
97, which is formed via an overmolding process. A manually pullable grip portion 96 of
button 92 is covered with the soft touch material and extends proximally of the housing
35. Flanges 98 laterally extend from the distal end of button 92 and, during pen cocking,
abut inward lips 100 formed in housing halves 36, 38 to limit withdrawal of the plunger
member from the housing. An indicating band 102 on button 92 is visible to a user when
the button has been properly withdrawn to prepare pen 20 for medication delivery.
Button 92 also includes a pair of diametrically opposed latches 101 at the distal ends of
slot-defined fingers 103. Latches 101 inwardly project within hollow 93, and due to the
resiliency of the fingers 103, snap-fit during manufacturing assembly over transversely
extending shoulders 105 of the input element 90 to prevent axial, proximal withdrawal of
the button 92 from the input element during operation.
Plunger element 90 is made of injection molded plastic and is designed in
conjunction with the housing to be rotatably fixed while slideable within housing 35.
Plunger element 90 includes a cruciform-shaped protuberance 107 that proximally
projects from a plate portion 108. Plate portion 108 is keyed to be rotatably fixed within
the button, and includes the latchable shoulders 105. Protuberance 107 fits within the
distal end of the force limiting biasing member 94 provided as a metal, helically coiled
compression spring. The proximal end of biasing member 94 fits around a cruciform-
shaped protuberance 109 formed on button 92 within hollow 93. Spring 94 is captured in
a pre-stressed state between the latched plate portion 108 and the interior end of button
92, which pre-stressing is at least as large as forces the manufacturer expects users to
apply on the plunger button during normal plunging to achieve proper pen operation. In
one embodiment, in which a mechanical advantage of nominally ten to one is provided
by the apparatus, the pre-stressing is in an amount of one pound. Thus, during normal
plunging, spring 94 does not further compress and the button 92 and input element 90
shift as a unit and without relative axial motion. Coil spring 94 is also designed with
sufficient spacing in its coiling, and with proper elastic properties, such that the spring,
by compression, can accommodate movement of button 92 from the cocked position to
the ready-to-be-cocked position without movement of plunger element 90, whereby
spring 94 can absorb plunging forces that could damage the internal components.
Plunger element 90 also includes a bar portion 110 and a block portion 114 which
both project distally from plate portion 108. Near its distal end, bar portion 110 includes
a laterally extending portion that serves as a U-shaped bearing or yoke 116. Yoke 116
extends and opens away from the pen axis. At its distal end, bar portion 110 terminates
in an upstanding lip 117 with a ramped face 118. Lip 117 serves as a catch or hook of
the apparatus locking mechanism. Yoke 116 receives the pin 120 of the gear set, which
pin defines an axis about which the gear set partially revolves or pivots during use.
Block portion 114 serves as a base to which a flexure or follower piece 122 of a partial-
cocking-preventing mechanism is insert molded during manufacture.
Follower piece 122 is made in one piece of a metal stamping and includes an
apertured mounting plate 124 that is secured to block 114 during insert molding. A pair
of resilient arms 126 longitudinally extend in parallel from mounting plate 124. Arms
126 serve as leaf springs and are spanned at their distal ends by web 128. A pawl 129
projects from web 128 toward housing half 36. Follower 122 directly engages a guide
135 of the partial-cocking-preventing mechanism. Follower arms 126 are closely backed
by ribs 82 to better ensure that pawl 129 is not twisted out of a proper engagement with
the guide during use.
Referring also now to Fig. 12, guide 135 is integrally formed with the interior
surface 37 of housing half 36 and includes a bar portion 138 having an angled, distal end
140 and an angled, proximal end 142. One longitudinally extending face of bar portion
138 provides a flat travel surface 146, and the opposite face of the bar portion 138
includes a travel surface 148 equipped with a plurality of ratchet teeth 150. Teeth 150
are engageable by pawl 129 to prevent distal movement of the plunger after only a partial
withdrawal of the plunger in preparation for injection. Teeth 150 can be customized
during manufacture to produce the desired number and volume of clicks during
movement of the pawl over the row of teeth during use. For example, the provision of a
large number of teeth, each having a relatively short height over which the pawl must be
cammed outward, may result in clicks that are less distinct and similar in sound to a
continuous, low volume buzz. Still further, instead of triangular teeth, the teeth may be
lobe-shaped, with the indentation between lobes being where pawl 129 engages to
prevent distal motion. Guide 135 further includes first and second abutment shoulders
152 and 154 molded into the housing.
The partial-cocking-preventing mechanism in the shown embodiment provides an
initial reluctance to pen cocking due to the sliding of pawl 129 over distal end 140, a
tactile and audible notice of plunger movement, along with a prevention of plunger return
prior to a complete dose preparation, due to the movement of pawl 129 over the row of
teeth 150, an audible notice of complete dose preparation by the striking of abutment
shoulder 152 by a distal end portion 130 of one resilient arm 126, an initial reluctance to
injection due to the sliding of pawl 129 over proximal end 142, and an audible notice of
injection completion by the striking of shoulder 154 by a distal end portion 131 of the
other resilient arm 126.
The gear set utilized in the injection pen is configured to convert plunger member
motion of a first distance into drive member motion of a second distance less than the
first distance. The gear set shown at 52 is made from a lightweight material such as
plastic, and utilizes first and second sized pinions.
The first or larger sized pinion 160 includes an arcuate section of external gear
teeth 162 that mesh with rack 84. An arcuate section of gear teeth is all that is required
due to the small angle of revolution of the pinion necessary for use of the shown pen,
which small angle or partial roll is possible due to the nominally ten to one mechanical
advantage provided by the shown gear ratio.
The smaller sized pinion 166 has the same axis of rotation as pinion 160 and
includes only an arcuate section of external gear teeth 168. Gear teeth 168 have a pitch
diameter that is less than the pitch diameter of gear teeth 162. In the shown embodiment,
such diameter is about 90% of the diameter of gear teeth 168, which ratio provides the
nominally ten to one mechanical advantage. Smaller ratios may be employed, such as
down to 50%, which realizes a two to one mechanical advantage, and larger ratios may
alternatively be employed, such as realizing a ratio for a sixteen to one mechanical
advantage. Gear teeth 168 meshably engage drive member rack 80, which rack is
parallel to and disposed on the same side of the pinion axis as rack 84.
Although pinion 160 and pinion 166 are shown integrally formed, these
components can be separately formed and assembled together so as to be corotatable.
Pinions 160 and 166 share a common axis of rotation. A pin or axle 120 is located at
such axis and is shown integrally formed with the pinions. Pin 120 is sized and shaped
to fit into, and pivot or partially rotate within, the opening of yoke 116 during use.
During pen use, gear set 52 is shifted proximally and then distally in the
following manner. The gear set is shifted axially with the plunger element 90 to which it
is pinned as such plunger element is pulled out and subsequently plunged in. As gear set
52 moves proximally, the gear set rotates due to pinion 160 being in rolling engagement
with fixed rack 84. As gear set 52 rotates, pinion 166 rolls along drive member rack 80,
but also effectively pulls for a short distance the pinion-engaging piece 62 proximally
relative to the cartridge-engaging piece 60 held by the pawls 72. During plunger element
plunging, pinion 160 rolls backs along rack 84, and pinion 166 rolls along rack 80 while
effectively pushing pinion-engaging piece 62 to advance cartridge-engaging piece 60
Injection apparatus 20 includes a locking mechanism that prevents use of the
apparatus after a final intended dose has been administered thereby. The locking
mechanism automatically operates during the injection of such final dose to prevent the
plunger from being withdrawn thereafter.
The locking mechanism includes a generally C-shaped latching element,
generally designated 180. Latching element 180 is formed in a single piece, such as a
metal stamping, and includes a spring plate 182, a pair of installation flanges 184, and a
latch lip 186. Flanges 184 depend from the distal edge of spring plate 182 and include
lower ends 187. During pen manufacture, ends 187 press fit into complementary slots
formed by wall 188 and barbed ribs 189 of the housing half 38 to assemble latching
element 180 to the housing to be axially fixed relative thereto.
Centrally located along the width of the plate 182 is a depending skid 190. Skid
190 has a lower surface 192 that is blade-shaped and longitudinally extends. Blade 192
directly contacts and slides along an axially extending, smooth surface 71 of cartridge-
engaging piece 60. Skid 190 is formed by cutting and bending downward a portion of
plate 182 during manufacture. An additional cut-out 194 opposite the opening formed by
the bending downward of skid 190 results in a better symmetry of the plate portion 182
to aid in providing a more uniform springing effect during latching. Latch lip 186
depends from the proximal edge of spring plate 182 in the same direction as skid 190
depends, and is proximally spaced slightly from skid 190. Skid 190 is selected to be of
such a height that its engagement with bar surface 71 results in spring plate 182 being
deflected upward and away from its neutral position, whereby lip 186 is laterally spaced
from the plunger member 54 extending thereunder, and in particular is spaced laterally
from the hook 117 of bar portion 110. During initial use, blade 192 slides along the
untoothed portion of the drive member at surface 71, with latch lip 186 being spaced
from the plunger against the resiliency or spring-force provided by spring plate 182.
When cartridge-engaging piece 60 is driven distally to complete its final injection, blade
192 slides off the proximal end 65 of smooth surface 71, allowing the resiliency of spring
plate 182 to snap latch lip 186 downward. As latch lip 186 moves down, in the event
that the plunger member 54 has already been fully shifted distally, the latch lip 186 fits
proximally of the hook 117 of bar portion 110. In the event the shifting plunger has yet
to have been shifted distally fully during the final dose administration, as the plunger
motion continues the ramped face 118 engages latch lip 186 to temporarily cam latch lip
186 upward, and when the plunger is moved sufficiently distally, latch lip 186 then snaps
down over hook 117. This latching of latch lip 186 with hook 117 prevents any further
proximal motion of bar portion 110, and thereby of the entire plunger member 54.
Although shown directly engaging input element 90, the latching element may engage
other portions of the drive mechanism within the scope of the invention.
Referring now to Fig. 13, there is shown an exploded, perspective view of another
embodiment of a medication dispensing apparatus of the present invention. The
apparatus, generally designated 220, is substantially similar to apparatus 20, with some
differences being identified below.
In particular, the locking mechanism preventing use after an administration of a
final intended dose includes a generally L-shaped latching element, generally designated
225, formed in a single piece, such as a metal stamping. The spring plate 227 of latching
element 225 includes a centered aperture 230 that defines webs 232 and 234. Depending
from spring plate 227 along the proximal edge of aperture 230 is a transversely extending
skid 236 having an upwardly curved lower end 238.
Generally elliptical slots 242 formed through the spring plate form a pair of rims
240 that each include a portion that upwardly projects beyond the top of the spring plate.
Rims 240 project from the spring plate in a direction opposite to the direction skid 236
projects. Rims 240 are proximally spaced from skid 236. The shown rims 240 serve as a
pair of latching lips each providing a hook-contacting surface that is larger than that
formed merely by the small thickness of the shown spring plate, thereby better
The proximal edge of spring plate 227 is upturned at 244 to promote the spring
plate being cammed over the locking mechanism hooks as may be necessary. Skid 236
still is of a height that its engagement with the bar surface 71' results in spring plate 227
being directed upward and away from its neutral position, whereby rims 240 are spaced
from the apparatus plunger disposed thereunder, and in particular from the bar portion
In conjunction with this modified latching element, the plunger element 260
includes a pair of spaced, parallel bar portions 262, 264 that project distally from a plate
portion 266. Each of bar portions 262, 264 includes a lip 266, with a ramped face 267, to
serve as a rim-engaging hook of the locking mechanism when inserted through the spring
plate openings 240. Only one of the bar portions, namely bar 262, is provided with the
yoke for mounting the gear set 270.
The plunger button of the embodiment of Fig. 13 is formed of two pieces, namely
274 and 276, which are fixedly secured together during manufacturing assembly. Piece
274 is a different color than piece 276, and the pieces 274 and 276 are sized such that the
proximal end region of piece 274 serves as a colored indicating band that is visible to a
user when the plunger button is fully withdrawn to prepare the pen for delivery.
The embodiment of Fig. 13 has a mechanical advantage of just over seven, as a
ratio of the gear pitch diameters of gear set 270 is 86%.
The cartridge engaging piece 280 may be designed with ratchet teeth that are
adapted for an initial shipping/storage of a ready-to-be-cocked apparatus in which, while
pawls 282 are each similarly situated at the start of their respective ratchet tooth (i.e
proximate the transverse face of the distally adjacent tooth), both anti-back-up pawls 284
are similarly partially cammed outward by their engagement with a middle length portion
of different ratchet teeth. These different ratchet teeth so initially engaged by pawls 284
have a shallower slope and therefore lesser height, as measured from the longitudinal
axis of the apparatus, than the other teeth in the row, thereby reducing the stress on pawls
284 prior to the first use of the apparatus by the user. In order to possibly account for a
single test cycle by the manufacturer during assembly, two adjacent lesser height teeth in
each row for engagement with pawls 284 may be provided.
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, other forms of drive systems, including but not limited to drive systems
providing mechanical advantage using rack and pinion designs, possibly such as
disclosed in the materials herein incorporated by reference, may be utilized. For
example, a gear set may have pinned to its axle an output member which engages the
cartridge piston. Such gear set may have one arc of gear teeth that engage a housing
rack, and another arc of gear teeth that engage a plunger rack, which racks are positioned
on opposite sides of the gear set's axle. Such arcs of gear teeth may have a common
pitch diameter, or the housing rack-engaging gear teeth may have a pitch diameter which
is smaller or larger than the plunger rack-engaging gear teeth. Still further, in another
version the gear set may be pinned to the housing. A plunger rack of the system may
engage gear teeth of the gear set having a larger pitch diameter, and a rack of the output
member which engages the cartridge piston may engage teeth of the gear set having a
smaller pitch diameter. Still further, for an unpinned or rolling gear set, a plunger rack
may engage gear teeth with a first pitch diameter, a rack of an output member which
engages the cartridge piston may engage gear teeth with a smaller pitch diameter, and a
housing rack, which is positioned on the opposite side of the gear set's center from the
plunger and output racks, may engage gear teeth with a pitch diameter that is the same or
smaller than that of teeth engaging the plunger rack. Still further, in a rolling gear set
design related to the materials herein incorporated by reference, the plunger rack may
engage teeth with a smaller pitch diameter than the pitch diameter of gear teeth engaging
the housing rack. 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.
1. A medication dispensing apparatus (20, 220) comprising:
a housing (35);
a drive member (60, 280) within said housing and movable in a distal direction;
a fluid container (28) defining a medicine-filled reservoir (30) with a movable piston (32)
at one end and an outlet at the other end, said piston engageable by said drive member to be
advanced toward said outlet a distance equal to a distal movement of said drive member when
said drive member is moved distally;
a plunger element (90, 260);
a gear set (52) comprising first and second pinions (160, 166);
a first rack (84) engaged with said first pinion and axially stationary within said housing;
a second rack (80) engaged with said second pinion and movable within said housing on
a piece (62) clutchably connected to said drive member;
chararacterized in that:
said gear set pivotal on said plunger element and shiftable proximally and distally with
the plunger element;
a latching element (180, 225) having a latching lip (186, 227) and a skid (190, 236);
said drive member having an axially extending, skid-engaging surface (71) along which
said skid is slidable as said drive member passes distally during advancement during plunger
element shifting in the distal direction, said skid-engaging surface having an axial length and a
proximal end (65), said drive member along said axial length structured and arranged with said
skid so as to maintain said latching lip against a spring force in a first position free of a latchable
element (117, 226) disposed on said plunger element during dose preparing and injecting prior to
a final dose administration; and
wherein said skid-engaging surface shifts distally of said skid such that said skid passes
beyond the proximal end upon administration of a final dose allowing said latching lip to be
urged by said spring force from said first position to a second position for engagement with said
latchable element to physically lock said plunger element to prevent further dose preparing and
2. The medication dispensing apparatus as claimed in claim 1, wherein said proximal
end of said skid-engaging surface comprises a proximal end of said drive member.
3. The medication dispensing apparatus as claimed claim 1, wherein said skid is
disposed distally of said latching lip.
4. The medication dispensing apparatus as claimed in claim 1, wherein said skid
comprises a blade shape member that extends axially, and wherein said latching lip comprises a
transversely extending flange.
5. The medication dispensing apparatus as claimed in claim 1, wherein said latchable
element comprises a ramped distal face (118, 267) over which said latching lip is cammable to
reach a latching engagement with said latchable element.
6. The medication dispensing apparatus as claimed in claim 1, wherein said latching
element is axially fixed to said housing by at least one flange (184) fit into a slot provided in said
7. The medication dispensing apparatus as claimed in claim 1, wherein said spring
force acting on said latching element comprises a resiliency of said latching element tending to
return said latching lip to a neutral arrangement.
8. The medication dispensing apparatus as claimed in claim 7, wherein said latching
element comprises a one piece metal stamping.
9. The medication dispensing apparatus as claimed in claim 1, wherein said skid-
engaging surface is smooth.
10. The medication dispensing apparatus as claimed in claim 1, wherein said latching
lip comprises a rim (240) along an opening (242) through which a latchable element extends to
reach a latching engagement with said latching element.
A MEDICATION DISPENSING APPARATUS
A medication dispensing apparatus (20, 220) comprising:
a housing (35); a drive member (60, 280) within said housing ,a fluid container (28)
defining a medicine-filled reservoir (30) with a movable piston (32) at one end; a
plunger element (90, 260);a gear set (52) including first and second pinions (160,
166); a first rack (84) engaged with said first pinion, a second rack (80) engaged with
said second pinion and movable within said housing on a piece (62) clutchably
connected to said drive member;said gear set pivotal on said plunger element and
shiftable proximally and distally with the plunger element; a latching element (180,
225) including a latching lip (186, 227) and a skid (190, 236);said drive member
including an axially extending, skid-engaging surface (71) along which said skid is
slidable as said drive member passes distally during advancement during plunger
element shifting in the distal direction , said skid-engaging surface shifts distally of
said skid such that said skid passes beyond the proximal end upon administration of a
final dose allowing said latching lip to be urged by said spring force from said first
position to a second position for engagement with said latchable element to physically
lock said plunger element to prevent further dose preparing and injecting.
|Indian Patent Application Number||2569/KOLNP/2006|
|PG Journal Number||02/2014|
|Date of Filing||07-Sep-2006|
|Name of Patentee||ELI LILLY AND COMPANY|
|Applicant Address||Lilly Corporate Center, City of Indianapolis Indiana 46285|
|PCT International Classification Number||A61M5/00; A61M5/315|
|PCT International Application Number||PCT/US2005/010206|
|PCT International Filing date||2005-03-25|