U.S. patent application number 09/768761 was filed with the patent office on 2001-06-28 for autoinjector.
Invention is credited to Amark, Mikael, Bergens, Thomas.
Application Number | 20010005781 09/768761 |
Document ID | / |
Family ID | 20413084 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010005781 |
Kind Code |
A1 |
Bergens, Thomas ; et
al. |
June 28, 2001 |
Autoinjector
Abstract
An autoinjector for replaceable containers of syringe type,
comprising a barrel of axially roughly constant cross-section, a
front opening with or for an injection needle and at least one
movable rear piston, optionally with a plunger connected thereto,
inserted in the barrel for the displacement of a container content,
the autoinjector comprising a) a housing, b) a container carrier,
arranged for reception of the container and arranged movably in
relation to the housing in container axial direction between a
rear, needle-covering, position and a forward, needle-exposing,
position, c) an autopenetration mechanism, comprising at least a
penetration head and a penetration drive, the penetration head
being arranged for movement of the barrel or carrier in the forward
direction and the penetration drive being operable to apply force
between the housing and the penetration head, d) an autoinjection
mechanism, comprising at least an injection head and an injection
drive, the injection head being arranged for movement of the piston
or plunger in the forward direction and the injection drive being
operable to apply force between the housing or the carrier and the
injection head, e) optionally an autoreturn mechanism operable to
apply force between the housing and the barrel or carrier for
movement thereof in the rearward direction and f) a control system
for sequencing the operation of at least the autopenetration and
autoinjection mechanisms, at least comprising a releasable
penetration lock for the autopenetration mechanism and a releasable
injection lock for the autoinjection mechanism. The carrier is
designed to accommodate either of at least two containers of
different length and/or width and at least one damper arranged for
energy absorption from the autopenetration and/or autoinjection
movement.
Inventors: |
Bergens, Thomas; (Ingaro,
SE) ; Amark, Mikael; (Brottby, SE) |
Correspondence
Address: |
DINSMORE & SHOHL, LLP
1900 CHEMED CENTER
255 EAST FIFTH STREET
CINCINNATI
OH
45202
US
|
Family ID: |
20413084 |
Appl. No.: |
09/768761 |
Filed: |
January 24, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09768761 |
Jan 24, 2001 |
|
|
|
09411954 |
Oct 4, 1999 |
|
|
|
60107851 |
Nov 10, 1998 |
|
|
|
Current U.S.
Class: |
604/208 ;
604/156 |
Current CPC
Class: |
A61M 5/326 20130101;
A61M 2005/2086 20130101; A61M 5/2033 20130101; A61M 5/3204
20130101; A61M 2005/2418 20130101; A61M 5/2053 20130101; A61M
2005/3143 20130101; A61M 5/24 20130101; A61M 2005/206 20130101;
A61M 2005/202 20130101 |
Class at
Publication: |
604/208 ;
604/156 |
International
Class: |
A61M 005/20 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 1998 |
SE |
9803662-7 |
Claims
1. An autoinjector for replaceable containers of syringe type,
comprising a barrel of axially roughly constant cross-section, a
front opening with or for an injection needle and at least one
movable rear piston, optionally with a plunger connected thereto,
inserted in the barrel for the displacement of a container content,
the autoinjector comprising a) a housing, b) a container carrier,
arranged for reception of the container and arranged movably in
relation to the housing in container axial direction between a
rear, needle-covering, position and a forward, needle-exposing,
position, c) an autopenetration mechanism, comprising at least a
penetration head and a penetration drive, the penetration head
being arranged for movement of the barrel or carrier in the forward
direction and the penetration drive being operable to apply force
between the housing and the penetration head, d) an autoinjection
mechanism, comprising at least an injection head and an injection
drive, the injection head being arranged for movement of the piston
or plunger in the forward direction and the injection drive being
operable to apply force between the housing or the carrier and the
injection head, e) optionally an autoreturn mechanism operable to
apply force between the housing and the barrel or carrier for
movement thereof in the rearward direction and f) a control system
for sequencing the operation of at least the autopenetration and
autoinjection mechanisms, at least comprising a releasable
penetration lock for the autopenetration mechanism and a releasable
injection lock for the autoinjection mechanism, characterized in
the improvement comprising that the carrier is designed to
accommodate either of at least two containers of different length
and/or width and at least one damper arranged for energy absorption
from the autopenetration and/or autoinjection movement.
2. The autoinjector of claim 1, characterized in that the
penetration lock is arranged for holding the penetration head
relative the housing and that the releasable injection lock is
arranged for holding the injection head relative the housing, the
carrier or the penetration head, in predetermined rear cocked
positions.
3. The autoinjector of claim 2, characterized in that in the cocked
positions there is a space between the penetration head and the
barrel or carrier and a space between the injection head and the
piston or plunger respectively.
4. The autoinjector of claim 1, characterized in that the control
system includes a manual trigger arrangement at least acting to
release the penetration lock.
5. The autoinjector of claim 1, characterized in that the
releasable injection lock is connected, directly or indirectly,
between the injection head and the penetration head.
6. The autoinjector of claim 1, characterized in that the control
system includes a structure on the housing releasing the injection
lock at a predetermined axial injection enabling position.
7. The autoinjector of claim 6, characterized in that in the
injection enabling position there is a space between the injection
head and the piston or plunger respectively.
8. The autoinjector of claim 1, characterized in that a single
drive acts as the penetration drive and the injection drive.
9. The autoinjector of claim 8, characterized in that the single
drive acts on the injection head.
10. The autoinjector of claim 9, characterized in that an
autoreturn mechanism is present and that the control system
comprises an autoreturn enabling mechanism disengaging the
container and carrier from the single drive.
11. The autoinjector of claim 1, characterized in that the
penetration drive and the injection drive are separate, that the
penetration drive is weaker than the injection drive and that the
injection drive is arranged to apply force between the carrier and
the injection head.
12. The autoinjector of claim 11, characterized in that an
autoreturn mechanism is present and that the control system
comprises an autoreturn enabling mechanism disengaging the
container and carrier from the penetration drive.
13. The autoinjector of claim 10 or 12, characterized in that the
autoreturn enabling mechanism includes a release structure,
arranged to enable the disengagement, with predetermined axial
location in relation to the container front.
14. The autoinjector of claim 10 or 12, characterized in that the
autoinjection mechanism comprises an autoreturn enabling mechanism
based on force increase at piston bottoming out.
15. The autoinjector of claim 14, characterized in that the force
is sensed between the injection head and the housing.
16. The autoinjector of claim 14, characterized in that the force
is sensed between the injection head and the carrier or
container.
17. The autoinjector of claim 16, characterized in that the
autoinjection mechanism comprises an injection conveyor, that the
injection drive acts between the injection head and the injection
conveyor, that the injection conveyor is connected to the carrier
in an axially movable manner with respect to the carrier, that a
counterforce, being weaker than the force of the injection drive,
is arranged between the injection carrier and the conveyor and that
the autoreturn enabling mechanism includes release mechanism acting
on a relative movement between injection conveyor and carrier.
18. The autoinjector of claim 14 to 17, characterized in that the
injection drive includes a damper.
19. The autoinjector of claim 1, characterized in that an
autoreturn mechanism is present and that the control system
comprises an autoreturn enabling mechanism disengaging the
container and carrier from the autopenetration force and the
autoinjection force.
20. The autoinjector of claim 1, characterized in that the damper
is included in the penetration head.
21. The autoinjector of claim 20, characterized in that the damper
includes a spring arranged in the axial direction and being weaker
then the force of the penetration drive.
22. The autoinjector of claim 21, characterized in that the
penetration head comprises at least two parts between which the
spring is arranged.
23. The autoinjector of claim 22, characterized in that the control
system is arranged to enable the autoinjection mechanism at
relative movement between the two parts of the penetration
head.
24. The autoinjector of claim 1, characterized in that the damper
is included in the injection head.
25. The autoinjector of claim 24, characterized in that at least a
part of the injection head is resilient and acts as damper.
26. The autoinjector of claim 1, characterized in that the damper
is a viscous damper arranged to retard the autoinjection
movement.
27. The autoinjector of claim 26, characterized in that the viscous
damper retardation dominates over the syringe flow
restrictions.
28. The autoinjector of claim 26, characterized in that the
autopenetration movement is unretarded or at least less retarded
than the autoinjection movement.
29. The autoinjector of claim 26, characterized in that the viscous
damper is connected, directly or indirectly, between the
penetration head and the injection head, to act at relative motions
therebetween.
30. The autoinjector of claim 26, characterized in that the viscous
damper is arranged in parallel with the injection head
movement.
31. The autoinjector of claim 26 to 30, characterized in that the
penetration drive is separate from, and provides a less strong
force than, the injection drive.
32. The autoinjector of claim 1, characterized in that the carrier
comprises a seat supporting the syringe barrel in a direction
radial to the barrel axis and that a flexible or spring biased
member is provided to force the barrel radially against the
seat.
33. The autoinjector of claim 32, characterized in that the member
is connected to a closure, allowing lateral insertion of the
container in the carrier.
34. The autoinjector of claim 32, characterized in that the seat
comprises an axially extending V-shaped trough.
35. The autoinjector of claim 32, characterized in that the seat
comprises a front constriction, narrower than the container barrel
and wider than the container needle, arranged to prevent the
container front passing the constriction in the forward
direction.
36. The autoinjector of claim 1, characterized in that the carrier
is movable against a spring force biased in the rearward direction.
Description
TECHNICAL FIELD
[0001] An autoinjector for replaceable containers of syringe type,
comprising a barrel of axially roughly constant cross-section, a
front opening with or for an injection needle and at least one
movable rear piston, optionally with a plunger connected thereto,
inserted in the barrel for the displacement of a container content,
the autoinjector comprising a) a housing, b) a container carrier,
arranged for reception of the container and arranged movably in
relation to the housing in container axial direction between a
rear, needle-covering, position and a forward, needle-exposing,
position, c) an autopenetration mechanism, comprising at least a
penetration head and a penetration drive, the penetration head
being arranged for movement of the barrel or carrier in the forward
direction and the penetration drive being operable to apply force
between the housing and the penetration head, d) an autoinjection
mechanism, comprising at least an injection head and an injection
drive, the injection head being arranged for movement of the piston
or plunger in the forward direction and the injection drive being
operable to apply force between the housing or the carrier and the
injection head, e) optionally an autoreturn mechanism operable to
apply force between the housing and the barrel or carrier for
movement thereof in the rearward direction and f) a control system
for sequencing the operation of at least the autopenetration and
autoinjection mechanisms, at least comprising a releasable
penetration lock for the autopenetration mechanism and a releasable
injection lock for the autoinjection mechanism.
BACKGROUND
[0002] Autoinjectors are designed to facilitate injection
procedures over those required by manual use of common syringes and
to secure a proper injection result highly independent of
operational circumstances. Autoinjectors are typically used in
non-hospital environments, sometimes in emergency situations, and
by non-professionals like unskilled assistants or the patients
themselves, which operator groups may include sick, disabled,
elderly and child persons. The autoinjectors provide at least an
automatic injection step in which stored energy, for example from a
compressed spring, is released by a trigger to act on a syringe
piston or plunger for expulsion of syringe content. Frequently the
autoinjectors also provide an automatic penetration step in which
stored energy is used for propulsion of the syringe from a rear
position, in which the needle is hidden, to a front position, in
which the needle is at least partially exposed, to thereby relieve
the patient from the, sometimes fearful, task of inserting the
needle through the skin and to secure an always appropriate
penetration depth once the autoinjector front has been placed
against the skin. Autopenetration and autoinjection may take place
concurrently, e.g. in simple devices or for the intentional purpose
of allowing for an over depth distributed injection. Normally it is
desirable to limit injection until the needle has reached or is
close to its target location. Still some known injectors try to
obtain this feat with a single force system acting on syringe
piston or plunger for both purposes, relying for sequencing on the
normally lower needle penetration resistance than fluid ejection
flow resistance. Yet impact, propulsion inertia and friction cannot
prevent at least some leakage during penetration but above all, in
case the penetration movement is prevented or jams, injection will
entirely fail with preparation expelled on the skin or at improper
depth. Hence more advanced injectors applies penetration force
directly or indirectly on the syringe barrel, with single or dual
drive systems, which requires some control mechanism disabling
injection force application during most of the penetration phase
and enabling injection force only after proper penetration.
Autoinjectors may also provide an automatic needle retraction step
in which stored energy, typically stored during the penetration
movement in a weaker return counterspring, acts to push the syringe
back into the autoinjector after completed injection in order to
relieve the user from the task and risk of withdrawal, to verify
sequence completion to the user and to prevent inadvertent needle
pricks after use. Again, this function may need a control mechanism
enabling action of the return spring only after completed
injection, normally accomplished by separation of the penetration
and injection forces from the syringe at a certain forward extreme
for the piston or plunger, freeing the return spring for
action.
[0003] Most known autoinjectors are designed for use with a single
syringe type or even a single specialized and adapted syringe type
container in order to meet the various tolerance in dimensions,
sizes and forces involved and these requirements become more
pronounced when more of the advanced features outlined above are
included in the injector. Yet there is a need for autoinjectors
able to operate with a variety of syringe sizes, filling degrees,
preparation viscosities, aging properties, temperature conditions,
needles and flow characteristics. A manufacturer of a broad range
of preparations may need a device useful for many container types
and doses. Low cost preparations in particular cannot support
development of a unique device or syringe container of its own and
furthermore may require use of cheap standardized syringe types on
the market with a selected minimum size for each dose. Patients on
prescription of several pharmaceuticals may benefit from
replacement of several devices for a single universal one.
Manufacturers of injectors may find a broader market for their
autoinjectors if compatible with container variations.
[0004] The above objects meet with numerous problems. Variations in
size first require a syringe seat or carrier, not only able to
accommodate and guide the various container movements with small
lateral deviations, but also to secure appropriate start and end
positions with respect to both the injector front and the injector
mechanism. Variations in length or filling degree means differences
in start positions for penetration and injection, either requiring
a complicated device with adaptable start positions or long worst
case dead runs for the mechanism, creating strong and potentially
destructive impact forces or painful injection rates. The force
requirements are highly variable. Variations in diameter, for
example, means variations in injection force due to differences in
piston cross-section surface, even at similar hydraulic flow
pressures, as well as differences in piston to wall friction.
Further broadening in force requirements is caused by differences
in flow characteristics, such as resistance and obstructions in
syringe opening, needle lengths or diameters as well as receiving
tissue, and by differences in piston to wall friction, even at
constant diameter, due to manufacturing tolerances and aging,
typically resulting in increased friction due to an ongoing
depletion of lubricant in the piston to wall contact surface. It is
also well known that the first piston displacement requires a much
higher "break-loose" force than continued motion. An again
increased force may be desirable at the piston bottoming out to
fully squeeze out container content, of special value at precise
dosing or for expensive preparations. If the autoinjector drive
systems are proportioned for the highest force required by all the
abovesaid factors combined, they tend to be excessively strong for
less demanding combinations, besides becoming generally bulky and
ungainly. Applied in the penetration step the forces may damage or
destroy smaller or weaker glass containers and counteract a safe
penetration due to vibrations, shaking, recoil and rebound effects.
Applied to the injection step extreme pressures may damage the
container itself, deform the piston or blow away front sealing or
attachments and most probably cause pain and bruises in the
receiving tissue. As indicated above all these problems are
exaggerated if the high forces are combined with inertia effects
from substantial mechanism dead run. If, on the other hand, the
autoinjector is provided with means for adjusting the force to the
requirements of each container type, these problems can be reduced
but instead a more complicated device results and an additional
tuning step is expected of the user, defeating the basic
simplicity, safety and rapidity reasons for using autoinjectors.
Finally, a variety of container types, sizes and tolerances place
severe demands on the control mechanism for sequencing the
autoinjector phases, as the containers may require different
locations and conditions for shift between enabled and disabled
states.
[0005] Existing prior art does not seem to give much guidance to
the resolution of the abovesaid problems. Infusion pumps, typically
for slow speed administration in hospital settings, explicitly
usable for syringes of different sizes are known, as exemplified by
U.S. Pat. No. 4,652,260, U.S. Pat. No. 4,838,857, U.S. Pat. No.
4,976,696, U.S. Pat. No. 5,034,004 and U.S. Pat. No. 5,545,140, all
relating to injection by electric motor means where speed can
easily be controlled. Similar infusion pumps using mechanical drive
means under hydraulic speed control are known from U.S. Pat. No.
3,474,787, U.S. Pat. No. 3,605,745, U.S. Pat. No. 4,430,079, U.S.
Pat. No. 4,437,859, WO 88/10129 and GB 1,026,593 or under
mechanical speed control from U.S. Pat. No. 3,279,653 and U.S. Pat.
No. 3,886,938, although these references do not suggest any
adaptations for syringes of varying size. Common to all infusion
pump systems is that no penetration step is involved, and still
less an autopenetration step, or any needle return step.
Accordingly they provide no solutions in this regard or in
connection with sequencing such steps. Nor are any solutions to be
found in respect of the abovesaid force problems, due to the slow
speeds and flow pressures involved and due to the common practice
of initiating the infusion procedure by manually or automatically
placing driver heads cautiously against the syringe plunger. Any
overpressure arises so slowly that the infusion procedure easily
can be halted, automatically or manually after delivery of an alarm
signal.
[0006] Some autoinjector proposals try to cope with excessive
forces by including mechanical dampers in the form of impact
retarding springs, elastic gaskets etc., as exemplified by WO
94/13342, WO 95/04562 and DE 3,914,818. These proposals are not
made for the purpose of allowing syringe variations and are
entirely unsatisfactory and insufficient for the dramatically
broadened force requirements in these connections. Also the other
problems described are left unsolved.
[0007] The WO 95/31235 reference discloses an autoinjector which
can be used with syringe subassemblies of different sizes and of
standard type, having plunger shafts. However, no solution of
general nature is given. For each type an adapted medical module
has to be provided and the problem of allowing for different sized
syringes in a common carrier is not addressed and expulsion of
different doses require special stop surface arrangements in the
modules. Further, no solution is given for such arrangements in
connection with autopenetration force applied to the syringe barrel
rather than its shaft or for automatic needle return. The
arrangements described are unable to handle problems with high and
varying injection forces.
[0008] Accordingly there remains a need for autoinjector designs
better adapted for use with great variations in syringe size and
type and with improved capabilities for handling the problems
outlined.
THE INVENTION GENERALLY
[0009] A main object of the present invention is to provide an
autoinjector avoiding or ameliorating the above described problems.
A more specific object is to provide an autoinjector adapted for
use with container variations as outlined. Another object is to
provide an autoinjector able to perform its functions within a
broad range of injection force requirements. A further object is to
provide such an autoinjector with controlled injection speed.
Another object is to offer an autoinjector able to secure complete
emptying of containers. Still another object is to provide such
autoinjectors highly compatible with autopenetration and autoreturn
functions. Yet another object is to offer an autoinjector
compatible with autopenetration forces applied to container barrel
rather than its piston. A further object is to provide an
autoinjector able to sequence the operation phases with a common
control mechanism. Still another object is to offer such
autoinjectors requiring no more user actions on the device than
charging, cocking and triggering.
[0010] These objects are reached with the characteristics set forth
in the appended patent claims.
[0011] By including in the autoinjector a container carrier
designed to accommodate containers of different widths and/or
lengths the device is usable for a broad range of containers
without need for exchange of insertions or other adaptive actions
from the user. Variations in length also accounts for variations in
filling degree, especially in connection with syringe type
containers having a plunger of varying extension from barrel rear
end. When the carrier is designed to localize containers in the
device housing with an for all containers common initial position
of the container fronts relative the housing, a well-defined
penetration action is achieved with a common penetration stroke
length, again without any adaptive measure required from the user,
and facilitate autopenetration and autoreturn feature in the
device. In spite of any container rear end positioning variations,
common penetration and injection mechanisms can be used, even with
standard start positions, due to the presence of a damper, in the
sense of the invention to be further explained. The damper acts to
absorb otherwise destructive energy and serves to allow a broad
force repertoire for the device, yet may be designed for controlled
and unified delivery rates. The flexibility provided makes these
features highly compatible with all basic autoinjector designs
mentioned in the introduction overview and in particular force
application to sensitive container barrels in a penetration step is
allowed. Sequencing of autopenetration and autoinjection steps is
facilitated by common start positions made possible and release of
an autoreturn step is facilitated by a common piston end point, as
described, or by utilization of a force, rather than location,
dependent release condition, made possible by the characteristics
of damped drives.
[0012] Further objects and advantages of the invention will be
evident from the detailed description hereinbelow.
DETAILED DESCRIPTION
[0013] In the absence of explicit statements to the contrary, as
used herein expressions like "comprising", "including", "having",
"with" and similar terminology shall not be understood to be
exclusively restricted to recited element but shall be understood
to allow for the presence of further elements as well and shall be
understood to cover any element in integral, subdivided or
aggregate forms. Similarly, expressions like "connected",
"attached", "arranged", "applied", "between" and similar
terminology shall not be understood to cover exclusively direct
contact between the recited elements but shall be understood to
allow for the presence of one or several intervening elements or
structures. The same applies for similar expressions when used for
description of forces and actions.
[0014] The containers usable in the present autoinjector shall be
understood in broad terms and can generally be said to include a
barrel having a front part and a rear part defining a general axis,
an outlet for the preparation, typically comprising a liquid in
broad sense, arranged at the front part and at least one movable
wall arranged at the rear part, a displacement of which wall causes
the preparation to be moved towards or expelled through the outlet.
Positional and directional statements for both the container and
the autoinjector, such as "axial", "front" and "rear", shall be
understood with reference to the abovesaid parts of the container.
Barrel shape and movable wall have to be mutually adapted. The
barrel may have a substantially constant internal cross-section,
with a similarly constant barrel axis, between front and rear parts
giving a generally tube-shaped barrel, and most preferably the
cross-section is of the common circular type giving a substantially
cylindrical barrel. The movable wall is then preferably a
substantially shape-permanent, although possibly elastic, body
sealingly adapted to the internal barrel surface and preferably of
the piston type. At the front end of the barrel a needle, cannula
or a similar penetration device is arranged and the invention is
preferably used with containers wherein the needle axis is
substantially parallel with barrel axis, and most preferably
concentric therewith, resulting in that the penetration and the
injection movements are substantially parallel. Within these limits
and preferences a broad range of containers can be used with the
present autoinjector device, such as ampoules, cartridges,
carpoules and syringes. The container need not have a separate
plunger, in which case the autoinjector mechanism can act more or
less directly on the container piston, although it is often
preferred that the container has a plunger, in the sense of a part
protruding from barrel rear end, on which the autoinjection
mechanism can act for movement of the piston, since many
standardized devices are so designed and which facilitates
mechanism access. The autoinjector can with preference be used with
standard container types, e.g. as defined in DIN and ISO standards
and exemplified with "Hypak" type syringes. Also usable are dual or
multi chamber container types, known e.g. for preparations
demanding a mixing of two or more components or precursors before
administration. The components are kept separated by one or more
intermediate walls of different known designs, which walls divide
the barrel into several chambers, sometimes placed parallel along
cartridge axis but most commonly in stacked relationship along the
axis. Unification of the components may take place by breaking,
penetrating or opening a valve construction in the intermediate
walls. In another known design the intermediate wall or walls are
of the plunger type and flow communication between the chambers is
accomplished by moving the plunger to a by-pass section where the
interior wall has one or several enlarged sections or repeated
circumferential grooves and lands in a manner allowing by-flow of
rear chamber content into front chamber at displacement of the rear
movable wall. The chambers may contain gas, liquid or solids.
Generally at least one liquid is present. Most commonly in
pharmaceutical applications only two chambers are present and
typically contains one liquid and one solid, the latter being
dissolved and reconstituted during the mixing operation. For these
types of containers it is preferred that the mixing or
reconstitution step has already taken place when the container is
placed in the autoinjector.
[0015] The autoinjector device comprises a housing, which shall be
understood in broad sense and basically as a point of reference for
positional and directional statements for other parts and
components. It is preferred, however, that the housing also
actually enclose at least the mechanisms of the device and leave
exposed mainly the parts that should be accessible to the user,
such as arming, triggering and cocking controls. The container can
be attached to the housing in such a manner that it remains
exposed, although it is preferred that the housing also confines
the container, preferably also the needle until penetration is
initiated. Replacement of containers may be facilitated by any
known separation or openable arrangement, e.g. threaded or hinged
parts, although a preferred and convenient arrangement is to
provide an openable closure on the side of the autoinjector front
part, allowing lateral insertion of the cartridge by a roughly
radial movement in relation to container axis.
[0016] The autoinjector further comprises a container carrier,
having the dual purpose of receiving and holding the various
containers in defined relationship to the housing and mechanisms
and being axially movable in relation to the housing, for
penetration purposes, between a rear position and a front position,
movement between which positions is used for penetration. The
distance traveled between the positions should correspond at least
to the desired penetration depth and, when the needle is hidden
within the housing before the penetration step, the distance needed
for internal travel to expose the needle tip. The carrier should be
able to accommodate at least two and preferably several container
types of different width and/or length, preferably also differences
in other respects earlier mentioned, i.e. the carrier should have
features allowing releasable fixation and axial displacement
thereof without individual inserts or other auxiliary devices. This
can be accomplished by use of at least one flexible or spring
biased member arranged to press the container radially against at
least one rigid surface, preferably in the from of a trough
allowing acceptance of different widths, e.g. by having an axially
constant V-shaped profile. It is also preferred that the container
is axially fixed in the carrier, at least against forward
movements, e.g. by use of a stop surface, and preferably so that
all container types are similarly held, for example behind
container rear end fingergrips but preferably in front of barrel
front end, giving the advantages outlined.
[0017] The autoinjector shall contain at least an autopenetration
mechanism and an autoinjection mechanism and preferably also
contains an autoreturn mechanism to be further described below. The
mechanisms may be of any known types mentioned in the introduction
but, for reasons given, is preferably of the type applying
penetration force to the barrel or the container carrier, rather
than the piston or plunger. The autoinjection mechanism comprises
at least a penetration head, arranged for contact with the barrel
or carrier in the penetration step and possibly also maintained
under the injection step, and a penetration drive able to apply
force between the housing and the penetration head. The penetration
head can be a larger structure or aggregate accessible for the
autoinjection mechanism or control system. Similarly the
autoinjetion mechanism comprises at least an injection head,
arranged for contact with the container piston or plunger in the
injection step, and an injection drive able to apply force between
the housing and the injection head, between the penetration head
and the injection head or between the carrier and the injection
head. The distinction herein between the penetration head and the
injection head shall not exclude the use of a common head acting as
both penetration head and injection head, in which case the common
head should first act on the barrel or carrier and then on the
piston or plunger. It is preferred, however, to use at least
partially different head structures, among others facilitating
adaptations for their respective purposes and their proper
positioning for all container variations. A common drive can be
used for the single or dual head alternatives, which is possible
according to the invention and which gives the simplest device
construction. It is preferred to use different drives, though, in
which case the penetration drive is preferably made substantially
weaker than the injection drive, as penetration normally give
little resistance, which makes it possible to avoid the initially
mentioned vibration and rebound effects during the relatively large
penetration stroke while maintaining a strong injection drive.
[0018] A control mechanism for sequencing the penetration and
injection steps may comprise a releasable penetration lock arranged
for holding the penetration head relative the housing and a
releasable injection lock for holding the injection head either
relative the housing, which allows for entirely independent
injection start, or preferably relative the penetration head or
carrier, which allows for an aggregate of parts, including the
injection head and preferably also the injection drive, to move
forwards during penetration, thereby limiting the dead run for the
latter and adapting it to the container rear end sensed by the
penetration head. The locks are arranged to hold the heads in
predetermined rear cocked positions, to which positions it should
be possible to move the heads by an externally accessible handle or
similar control. It is preferred that in the cocked positions there
is a space between the penetration head and the barrel or carrier
and a space between the injection head and the piston or plunger
respectively, thereby allowing for containers of different lengths
or filling degrees. When the injection head is locked relative the
penetration head it is similarly preferred that a space remains
between the injection head and the piston or plunger after the
penetration stroke and before injection. The control system
preferably also includes an externally accessible manual trigger
arrangement at least acting to release the penetration lock.
Release of the injection lock can take place simultaneously with
the penetration lock, especially if the injection stroke is delayed
by speed controlled to be explained, but it is safer and preferred
to make the release at or close to the end of the penetration
stroke, either by using the increased force sensed by the
penetration head at the end of the penetration stroke, which gives
the most adapted release for any container, or a specific point at
the housing, which gives the overall simplest solution. When the
releasable injection lock is connected, directly or indirectly,
between the injection head and the penetration head or carrier as
said, this can be implemented by inclusion of a structure on the
housing releasing the injection lock at a predetermined axial
injection enabling position for the penetration. This is possible
both if separate drives are used for penetration and injection and
if single drive is used if the single drive acts on the injection
head.
[0019] As indicated it is preferred that the autoinjector also
includes an autoreturn mechanism including a return drive arrange
to apply force between the housing and the container barrel or
carrier for movement in the rearward direction. This can be done,
in a manner known per se, by allowing the return drive force to
give a constant bias rearwardly, such as by a counterspring, and
using a return drive force weaker than the force provided by the
penetration force. The control system may then comprise an
autoreturn enabling mechanism disengaging the container and carrier
from the autoinjection force and the autopenetration force, thereby
freeing the container for rearward motion. The penetration and
injection mechanisms should allow for unobstructed return, e.g. by
being laterally displaced or by having cavities for reception of
the container rear parts. For simplest design the autoreturn
enabling mechanism may include a release structure, arranged to
enable the disengagement, with predetermined axial location in
relation to the container front. Alternatively and preferably the
autoreturn enabling mechanism may be designed to react on the
increased force resulting from the piston reaching and being
stopped at the container bottom end, which secures complete
emptying and squeezing out of container content and furthermore is
highly independent of container type. In one embodiment this is
achieved in that the autoinjection mechanism comprises an injection
conveyor, that the injection drive acts between the injection head
and the injection conveyor, that the injector head is connected to
the penetration head via the injection conveyor, that the injection
conveyor is axially movable with respect to the penetration head,
that a counterforce, being weaker than the force of the injection
drive, is arranged between the injection conveyor and the
penetration head and that the autoreturn enabling mechanism
includes release mechanism acting on a relative movement between
injection conveyor and penetration head. Optionally the force based
release can be enabled only short before injection completion and
be disabled during the main part of the injector head movement not
to be activated by abnormal force increases, e.g. due to flow
blockages or container malfunction.
[0020] The various drives described may utilize stored energy in
any known form, such as electrical, gas pressure or gas releasing,
or preferably mechanical, the latter preferably in the form of
elastic members such as springs. The stored energy can be
transmitted to the force stated via corresponding conventional
transmission means, e.g. electromechanical, such as electric motors
or solenoids, hydraulic, pneumatic etc. system but preferably
mechanical springs are utilized.
[0021] According to the invention at least one damper shall be
present, which damper shall be able to absorb work, i.e. force
times way, energy forms. The damper may absorb the energy mainly
reversibly in elastic form, utilizing well known components for
this purpose, such as elastomeric materials, e.g. rubbers or
mechanical springs. For certain purposes it is preferred to use
in-elastic damper types, i.e. absorbing energy mainly irreversibly
and under heat generation, utilizing either materials being
permanently deformed but preferably, for repeated use, viscous
dampers in the meaning of having a fluid, gas or preferably a
liquid, arranged to pass a flow restriction or between shear
surfaces during displacement of its parts. Viscous dampers, or dash
pots, are well known components as such and may take a variety of
forms, e.g. axial, as exemplified by piston/cylinder types in which
the fluid passes constrictions in or around the piston or in
controlled shunt, or rotational, as exemplified by impellers
rotating in a fluid under generation of shear forces. Although some
of the abovesaid dampers, e.g. elasticly or inelastically
deformable materials, are able to absorb energy in more than one
direction, it is generally sufficient for the present purposes that
the damper can absorb energy in one direction. Still a transmission
may be needed, e.g. to transform a linear movement in the
autoinjector into a circular movement in rotational viscous
dampers, to permit space-conserving repositioning of the damper or
to allow for a force modifying lever arrangement. Generally it is
preferred to arrange the damper in parallel with the linear motion
to be damped for simplest overall layout. Preferably viscous
dampers can be arranged to be active only in one direction,
preferably the injection or penetration directions, but not in the
reverse, e.g. to allow unobstructed cocking or the device, which
can be accomplished in well known manners, e.g. by providing a
releasable connection of the damper or preferably by making the
flow restriction according to one-way valve principles.
[0022] The damper can be arranged for energy absorption from the
autopenetration movement, for which purpose the damper should yield
under a pressure weaker than the force provided by the
autopenetration drive but preferably be stronger than force
provided by the autoreturn mechanism when present. It follows that,
although for example a return counterspring in a autoreturn
mechanism may act as a damper, for the present purposes the damper
is separate and in addition thereto. Preferably the damper is
arranged to absorb energy at impact forces between the
autopenetration head and the container barrel or carrier, which
impact forces may occur at the forward extreme for the penetration
movement when the container/carrier aggregate stops and often also
in the beginning of the penetration movement at the attack of the
penetration head against barrel or carrier. The damper can be
arranged at or on the barrel or carrier but it is preferred to
include the damper in the autopenetration mechanism, anywhere
between the housing and the penetration head front. The penetration
head as such can be made wholly or partially resilient for best
overall simplicity but it is preferred to subdivide the head on at
least two parts and arrange the damper therebetween for best
control. It is further preferred to utilize the movement under
damper yield as a confirmation of penetration movement completion,
e.g. for release of the autoinjection phase. It is generally
preferred that needle penetration takes place rapidly, as this
limits the pain sensation and as there are no advantages in
extending this act. Accordingly it is generally preferred to
arrange the damper to be active only over a part, and preferably
only a minor part, of autopenetration movement, preferably the last
part thereof, possibly also the initial part, while leaving the
major part of the movement undamped. Since needle penetration
normally requires only small forces, furthermore fairly independent
of syringe types, the damping requirements are small and can
sometimes be omitted entirely when the force of the autopenetration
mechanism can be adapted to the penetration purpose solely, which
is the case especially when this drive is independent of the
autoinjection mechanism drive system.
[0023] Most preferably a damper is arranged for energy absorption
from the autoinjection movement, for which purpose the damper
should yield under a pressure weaker than the force provided by the
autoinjection drive. A damper may here be included for similar
impact preventing purposes as described above for the
autopenetration phase and similar considerations then apply, e.g.
be active only under the relevant part of the movement, typically
under the injection head attack phase against piston or plunger.
During autoinjection, however, it is preferred that a damper is
additionally or alternatively provided for the purpose of
controlling injection movement speed and force in order to make the
autoinjection phase usable for a broad range of forces with
maintained uniform movements speeds, as described in the
introduction. Typical injection times are between 0.5 to 30 seconds
and preferably between 1 and 10 seconds. Accordingly damping should
be active during a major part of the autoinjection movement,
preferably over substantially the whole injection stroke and
preferably also before injection head contact with plunger or
piston, the latter additionally acting to reduce attack and dead
run problems and allowing for use of different sized containers.
The drive force can and should be selected strong enough, and
preferably more strong than that required, for the most demanding
force requirement of all container alternatives designed for, as
the damper will limit speed and force sensed by the container to
acceptable levels also in less demanding situations. It is
preferred that the driver and damper in combination gives the
injection head a substantially stable speed already in idle run,
i.e. without container present, and most preferably roughly that of
acceptable maximum piston or plunger speeds. It is further
preferred that during the injection movement the resistance in the
damper is higher than the resistance, such as flow and friction
resistance, in the container. For these purposes viscous dampers,
as described, are preferred e.g. for allowing long damped movements
and for best damping characteristics. As indicated the damper
should preferably be arranged to be active during the actual
injection stroke as well as during any further initial length
necessary for allowing the injection head to start from a for all
container types contemplated common start position for the
injection phase. Any additional movement over that need not be
damped, e.g. any movement the injection head makes earlier during
the autopenetration phase, for example when in a preferred way
moving together with the penetration head during the
autopenetration phase. The latter can be accomplished if the damper
is connected between the autopenetration head and the autoinjection
head, whereby damper movement will only take place when the
injection head moves relative the penetration head, normally after
completed penetration. Similarly, any injection head movement after
completed injection need not, and preferably is not damped, e.g.
any movement during the autoreturn phase, which, however, is
automatically obtained in the preferred arrangement mentioned that
during autoreturn the carrier is simple released from the heads and
accordingly also under inactivated damper. In any case the
preferred connection principle is to install the damper at least
partially in parallel with the injection mechanism, so that during
the damped movement the damper parts necessarily and positively
moves when the injection head moves.
[0024] A further advantage of the damped autoinjection mechanism as
described may be obtained in connection with an autoreturn
mechanism, which as said needs that the control system provides a
release of the carrier at the end of the injection phase. As
generally described earlier, release can be controlled by the
arrival of injection head, piston or plunger at a certain location
corresponding to the piston arriving at the barrel front end and
here the damper acts to give a cautious release highly independent
of variations in container injection resistance. It is preferred to
use a damper in connection with the alternative mentioned in which
the release is controlled by an increased force generated at the
piston contact with container front. Here a damper, especially a
viscous damper, will give full control over the force increase as
during movement of the injection head the damper secures a
predetermined reduction of the injection drive nominal force
through energy consumption whereas at stop of the movement the
damper is inactivated and said full nominal force is restored
between drive and plunger head. Similarly at gradual retardation of
the injection head the force increase will be correspondingly
gradual. All in all a substantial force difference will be
available for use by the control system in performing release of
the autoreturn function. When, in a preferred manner this principle
is applied in the conveyor type arrangement included in the
autoinjection mechanism, as earlier described, the gradual force
buildup and substantial force difference provided by the damper
allow i. a. a long conveyor movement and significant force
difference between injection drive force and conveyor counterforce,
all serving to make the autoreturn release reliable, rugged and
adaptive.
[0025] Further details of the invention will be eident form the
description of specific embodiments in relation to the
drawings.
SUMMARY OF DRAWINGS
[0026] FIGS. 1A to 1D show schematically in section four
operational stages of a first embodiment of an autoinjector having
a common drive for autopenetration and autoinjection and having
elastic dampers.
[0027] FIGS. 2A to 2G show schematically in section seven
operational stages of a second embodiment of an autoinjector having
a common drive for autopenetration and autoinjection and being
modified for a viscous damper.
[0028] FIG. 3A to 3J show schematically in section ten operational
stages of a third embodiment of an autoinjector having a separate
drives for autopenetration and autoinjection and having a viscous
damper being arranged for force determined autoreturn release.
[0029] FIG. 4 shows a modification of the autoinjector of FIG. 3 in
which a linear damper is used.
DESCRIPTION OF DRAWINGS
[0030] FIG. 1A to 1D show schematically in section four operational
stages of a first embodiment of an autoinjector having a common
drive for autopenetration and autoinjection and having elastic
dampers. In FIG. 1A the autoinjector is in an initial cocked
position before triggering. FIG. 1B shows the device after the
autopenetration step, bringing the needle to an exposed position.
FIG. 1C shows the device during the injection phase when the piston
has been brought to an intermediate position within the container.
FIG. 1D shows the device after that the autoreturn mechanism has
moved the syringe back into a needle-hidden position. The
autoinjector, generally designated 100, comprises a housing 110,
divided into a rear housing part 111, essentially confining the
mechanism parts, and a front housing part 112, essentially
confining the container parts. The housing parts are separable,
allowing insertion and replacement of containers, generally
designated 120, and comprising a barrel 121, a front part 122 with
attached needle 123, a rear fingergrip part 124 and a piston 125
inserted in the barrel onto which piston a plunger 126 acts. A
removable needle cover 127 initially protects the needle. The front
housing part 112 also contains a container carrier, generally
designated 130, comprising an axially movable seat 131 for
reception of containers, a flexible insert 132 allowing
accommodation of containers of different diameters, which insert
has inwardly tapering surfaces 133 arranged to restrain container
front 122 from forward movements relative the carrier and being
pushed by inner sleeve structure 113 on the front housing part to
an engaging position at least when the carrier is in the needle
exposing position. A return spring 134 is arranged between the
front housing part 112 front end and carrier 130 for movement of
the carrier in the rearward direction. The seat has a knob 135
extending laterally through a slit in the hosing front part to an
externally accessible position for manual movement of the carrier
forwards against the bias of the return spring, e.g. for removal or
attachment of needle cover 127. The rear housing part 111 comprises
most of the device mechanisms. A common drive system includes a
spring 141 acting as both as penetration drive and injection drive.
The spring acts between housing rear end and an injection head 142
in resilient material giving impact damping and having a generally
U-shaped form with legs 143 able to flex laterally in and out and
forming a cavity therebetween able to receive, when in an
out-flexed position, the plunger 126 rear part during the
autoreturn phase. A penetration head aggregate, generally
designated 150, comprises a front generally sleeve-shaped syringe
plunger part 151, having a front surface 152 arranged for contact
with barrel rear end or fingergrip 124, and a rear plunger guide
153, having a front end 154 extending into the sleeve-like syringe
plunger part 151 and a rear end 155 extending well behind the
syringe plunger 151. Between the syringe plunger 151 and the
plunger guide 153 a compression damper spring 156 is arranged in
slots, biasing the plunger guide 153 towards a rear position
relative the syringe plunger 151. The control system can be said to
include an externally accessible releasable lock (not shown) for
holding the penetration head in the rear cocked position, and
thereby also holding the injection head 142 in its cocked position
to be explained, thereby serving both as penetration lock and
injection lock. The control system further comprises structures,
for sequencing the operation, by flexing the injector head legs
143. A first such structure comprises tapering surfaces 161 at the
syringe plunger 151 rear end, arranged to compress the legs 143
from an intermediate position (shown in FIG. 1A), in which the legs
act on the plunger guide 153, to a narrow position (shown in FIG.
1B and 1C), in which the legs are freed to land on syringe piston
126 and maintained compressed by channel 162 provided by the
plunger guide 153. The tapering surfaces become active for
compression of the legs when the plunger guide moves forward
relative the syringe plunger against the force of the damper
spring, which is weaker than the drive spring 141. A second control
structure comprises an expansion cavity 163 adapted to allow
expansion of the legs 143, at a position corresponding to plunger
126 final position at empty syringe, to an expanded position (shown
in FIG. 1D) allowing the plunger 126 to move into the space between
legs 143 under the action of return spring 134 to a needle-hidden
syringe position.
[0031] In FIG. 1A penetration head 150 is held in a rear cocked
position at a short distance from syringe barrel end or fingergrip
124. The injection head 142 is also held in a rear position since
legs 143 rests in a slot on plunger guide 153. The drive spring 141
is compressed. The container 120 is pressed to a rear needle-hidden
position by return spring 134. In FIG. 1B a trigger (not shown) has
been released and drive spring 141 has acted on injection head 142,
which in turn has acted on plunger guide 153 to move syringe
plunger 151, into contact with container barrel or fingergrip 124,
thereby moving the container and carrier 130 into a needle-exposed
position. At the end of this penetration movement the container and
carrier have stopped together with syringe plunger 151 but the
plunger guide 153 has continued its forward movement against the
weaker force of damping spring 156, the relative movement between
which parts has made the tapering surface 161 cause a compression
of legs 143 and the injection head has landed on container plunger
126. In FIG. 1C (showing the penetration aggregate in section
rather than view) the injection head 142 has moved container
plunger 126 a certain distance under expulsion of container content
and with legs 143 in maintained compressed condition by channel
surfaces 162. In FIG. 1D the piston 125 has arrived at container
front part 122, injection head legs 143 have arrived at expansion
cavity 163, the legs have expanded away from contact with the
plunger 126 and return spring 134 has moved container 120 and
carrier 130 to the initial rear needle-hidden position under
partial reception of the exposed rear plunger 126 part in the space
of the U-shaped injection head 142.
[0032] FIG. 2A to 2G show schematically in section seven
operational stages of a second embodiment of an autoinjector having
a common drive for autopenetration and autoinjection and being
modified for a viscous damper. In FIG. 2A the autoinjector is in an
initial cocked position before triggering. FIG. 2B shows the device
after the autopenetration step, bringing the needle to an exposed
position. FIG. 2C shows the device having just started the
injection phase when the injection head and piston has come into
contact. FIG. 2D shows the device at end of the injection phase at
initiation of autoreturn phase. FIG. 2E shows the device when
release of a ball lock has freed the injection head from the
injection drive. FIG. 2F shows the device after that the autoreturn
mechanism has moved the syringe back into a needle-hidden position
together with the injection head. FIG. 2G shows the device when the
main drive spring has been fully extended. The embodiment of FIG. 2
has many features in common with that of FIG. 1 and shall be
describe in detail only with respect to features principally
deviating therefrom. Referring first to FIG. 2A the autoinjector
200 comprises a housing 210 having a rear part 211 and a front part
212 separable for insertion of a container 220, with plunger 226,
in a movable carrier 230, biased rearwards by a return spring (not
shown). The rear housing part 211 comprises a drive system 240,
acting both as penetration drive and injection drive, having a main
compression spring 241, housed within a drive sleeve 242, acting on
a injection head aggregate, generally designated 250. The aggregate
250 comprises a U-shaped front of an upper rigid leg 251 and a
lower flexible leg 252. A tube 253 extends rearwards to the drive
and is attached to the drive sleeve 242 with a ball lock,
comprising a ball 254 and a control pin 255, with a ball releasing
cavity 256 and a front flange 257. A ball lock spring 258 gives the
control pin a forward, locked, bias versus the tube 253. A
penetration head aggregate, generally designated 260, comprises
front surfaces 261, arranged for contact with container barrel or
fingergrip, which surfaces are connected to a transport guide 262
having a catch 263, for reception of rigid leg 251, at a resilient
part of the transport guide, a guide rail 264, arranged for keeping
the flexible leg 252 in an in-flexed state, the guide rail 264
having a forward end 265, arranged to allow flexible leg 252 to
flex out. A further control structure comprises a cam surface 271
fixed with respect to the housing and having a thick rear part 272,
adapted to keep catch 263 of the transport guide 262 pressed
against the rigid leg 251 in engaged relationship, and a thin front
part 273, adapted to allow the catch 263 to flex out for
disengagement of rigid leg 251. Although not shown in detail the
device is adapted for use with a viscous damper, arranged between
the penetration head 260 and the injection head 250 to be active
only during relative movements therebetween. Dotted line 280
illustrates schematically a linear damper, such as a
piston/cylinder oil damper, attached between penetration head 260
front surfaces 261 and injection head 250 rigid leg 251, for
parallel axial movement of damper and injection movement.
[0033] In FIG. 2A penetration head 260 is held in a rear cocked
position by a releasable trigger mechanism (not shown). The
injection head 250 is also held in a rear position since rigid leg
251 is engaged in the catch 263. The drive spring 141 is compressed
and acts on the injection head as the control pin 255 is in its
locked state. The container 220 is pressed to a rear needle-hidden
position by the return spring. In FIG. 2B a trigger has been
released and drive spring 241 has acted on injection head 250,
which in turn has acted on penetration head 260 to move surfaces
261 into contact with container barrel or fingergrip, thereby
moving the container 220 and carrier 230 into a needle exposed
position. During this movement the viscous damper 280 is inactive
as the penetration head 260 and injection head 250 moves together.
In FIG. 2C the catch 263 section of the transportation guide 262 is
at the thin part 273 of cam surface 271 and has flexed out, thereby
freeing rigid leg 251 from the catch 263 and allowing the injection
head 250 for movement independent of the penetration head 260,
which is now decoupled form the drive spring 241. Viscous damper
280 is now active and serve to retard injection head 250 forward
movement during the injection movement. In the figure the
independent movability has also resulted in that the flange portion
257 of control pin 255 has come into contact with container plunger
226 for injection. Flexible leg 252 is still maintained in-flexed
by guide rail 264 of transportation guide 262, thereby preventing
the control pin 255 from moving rearwards. In FIG. 2D injection has
proceeded to end and the injection head 250 is in a forward extreme
position with respect to the housing and the penetration head 260.
In this situation the flexible leg 252 has reached the end 265 of
guide rail 264 and has flexed out, thereby freeing the flange 257
of control pin 255 for rearward movement against ball lock spring
258, which is weaker than drive spring 241. In FIG. 2E the control
pin 255 has moved rearwards with respect to the injection head 250
(which has moved a bit more forwards), placing ball releasing
cavity 256 at ball 254, thereby releasing the injection head from
the drive sleeve 242, resulting in disengagement from the drive
spring 241. In FIG. 2F a return spring at the front of housing
front part 212 has pushed the container 220 and container carrier
230 back into the rear needle-hidden position, unrestricted of the
drive spring 241 since the injection head 250 is decoupled
therefrom and moves with the container and as the penetration head
has been decoupled earlier. This movement is also unaffected of the
viscous damper 280 as both penetration head 260 and injection head
250 moves in concert. In FIG. 2G the drive spring 241 and drive
sleeve 242 have continued their decoupled movement to a forward
extreme position in which the drive spring 241 is fully extended
(partial extensions not shown in earlier Figures).
[0034] FIG. 3A to 3J show schematically in section ten operational
stages of a third embodiment of an autoinjector having a separate
drives for autopenetration and autoinjection and having a viscous
damper being arranged for force determined autoreturn release. The
operational stages are shown for two syringes of both different
lengths and widths, drawn in an overlapping manner in the initial
Figures. In FIG. 3A the autoinjector is in an initial cocked
position. In FIG. 3B the syringe and carrier have been brought
forward manually for access and removal of a needle cover and in
FIG. 3C the syringe is again in the rear position ready for
triggering. In FIG. 3D the device has been triggered,
autopenetration has taken place and the injection head is released
for forward motion. FIG. 3E shows the device after partial
injection of syringe content and FIG. 3F at the end of the
injection stroke. In FIG. 3G the pressure increase at plunger
bottoming out has caused compression of a rear counterspring used
for release of the main spring. In FIG. 3H the released syringe has
moved back into a needle hidden position. FIG. 3I shows the device
re-cocked and FIG. 3J the device after syringe removal, ready for
replacement. The autoinjector, generally designated 300, comprises
a housing 310, in this embodiment an integral structure with a
front closure, laterally openable for access to the carrier. The
housing among others have a front slit 311 for a remover button,
foundations 312 for a return spring and a control structure 313 for
a release hook. The syringe type container, generally designated
320 and shown in two sizes as said, comprises barrels 321, front
parts 322 with attached needle 323, rear fingergrip parts 324 and
plungers 326. A removable needle cover 327 initially protects the
needle. The housing 310 also contains a container carrier,
generally designated 330, comprising an axially movable seat 331
for reception of containers, which seat has inwardly directed
surfaces 332 arranged to restrain container front 322 from forward
movements relative the carrier. Surrounding the seat 331 is a cover
remover 333 having a forward restriction 334 gripping behind the
needle cover 327 and being axially movable relative the carrier by
manipulation of an externally accessible button 335, extending
through the housing slit 311. Return springs 336 are arranged
between the housing foundations 312 and rear flanges 337 on carrier
330, via rear flanges 338 on the remover 333, the return springs
336 being biased for movement of the carrier in the rearward
direction. The carrier 330 extends rearwardly to form a support
part 339, which support houses parts of the injection mechanism to
be described. An autopenetration mechanism, generally designated
340, comprises a penetration drive spring 341 acting on a
penetration head structure 342, having a contact surface 343
arranged for pushing the syringe barrel 321 or fingergrip 324
forwards. The penetration head 343 also comprises a trigger button
344 extending through the housing 310 wall and a tapering surface
345 arranged for cooperation with another structure to deflect the
rear part 346 of the penetration head out of engagement with the
drive spring 341. The autoinjection mechanism, generally designated
350, comprises a conveyor 351, forming a base for the injection
drive, the conveyor extending forwardly into a toothed rail 352 of
a length corresponding to at least the stroke length for the
injection head. A head hook 353 is also arranged on the conveyor.
An injection drive spring 354 acts between the conveyor 351 and an
injection head 355, axially movable in relation to the conveyor and
arranged for displacement of the syringe plunger 326. A rotational
type dashpot damper 356 has its stator part 357 attached to the
injector head 355 and its toothed rotor wheel 358 engaged with the
toothed rail 352. Connected with the injection head 355 is also an
externally accessible cocking handle 359 extending into a pusher
362 for the penetration drive spring 341. The conveyor 351 is
arranged axially movable in relation to the carrier 330 support
part 339 via a counterspring 360 between these parts, which
counterspring is weaker than the injection drive spring 354 and
arranged to bias the conveyor 351 forwardly with respect to the
support part 339. This arrangement being part of the control system
to be explained. The control system can also be said to include the
housing control structure 313, arranged to tilt the head hook 353
and freeing the injection head 355 at a certain axial location for
the carrier with respect to the housing, and a structure 361 on the
conveyor, arranged to cooperate with the tapering surface 345 on
the penetration head to disengage the latter from the penetration
spring 341.
[0035] In FIG. 3A penetration head 342 is in a rear cocked position
retained by trigger 344 locked to the housing. The penetration
drive spring 341 is compressed. The contact surface 343 of the
penetration head 342 is located in a rear position allowing for
insertion of different syringe sizes with different distances to
the penetration head, as illustrated by the two fingergrip 324
positions shown. The penetration head dead run necessary for the
shorter syringes is no problem since the separate penetration drive
spring 341 need not be stronger than necessary for needle
penetration and return spring 336 compression. Unaffected by the
autopenetration mechanism 340 the return springs 336 push the
carrier 330, syringe 320, remover 333 and autoinjection mechanism
350 to the retracted, needle hidden, position. The injection head
355 is kept in a start position relative the conveyor 351 by hook
353 and with injection drive spring 354 compressed. Also for the
injection head 355 in this position there is a sufficient clearance
to allow for different plunger positions due to differences in
syringe sizes or filling degrees, which clearance is made possible
in spite of the strong injection drive spring 354 as any excessive
injection head 355 speed is prevented by damper 356. Spring 354 can
be dimensioned for the largest force requirement contemplated for
any syringe. In FIG. 3B button 335 of remover 333 has been moved
forwards against springs 336, compressed between foundations 312
and rear flanges 338 of remover 333, whereby forward restriction
334 has freed needle cover 327 from syringe front part 322 while
the syringe itself remains in the retracted position. In FIG. 3C
button 335 has been released and the remover 333 unit has returned
back under influence of return springs 336. The device is now ready
for initiation. In FIG. 3D the trigger 344 has been pushed, the
penetration drive spring 341 has moved penetration head 342
forwards to engage contact surface 343 with syringe fingergrip 324
(only the larger syringe is shown in this and subsequent Figures)
and propel it forwards to the forward, needle 323 exposed,
position. In doing so the whole aggregate of syringe 320, carrier
330, remover 333 and carrier support 339 with injection mechanism
350 moves forward and this penetration movement is highly
independent of syringe size since all syringe fronts are located at
the same position. Penetration head action on the syringe lowers
the retention requirements for the syringe in the carrier seat
although an alternative is to let the penetration head act on the
carrier instead. Also shown is that head hook 353 has been tilted
by control structure 313, thereby freeing injection head 355 for
forward motion relative conveyor 351. In FIG. 3E injection head 355
has moved forward with respect to conveyor 351 under influence of
injection drive spring 354 to push plunger 326 to an intermediate
position. Under his movement damper 356 is active as it moves
axially together with the injection head 355 while its rotor part
358 is forced to rotate when moving along toothed rail 352. In FIG.
3F the syringe 320 is empty and injector head 355 and plunger 326
stop. Also the damper 356 stops resulting in an elimination of
damper friction and an increase in injection drive spring 354 force
acting between the injection head 355, and thereby carrier 330 with
support 339, and conveyor 351. In FIG. 3G this force increase has
resulted in that conveyor 351 has moved back with respect to
carrier 330, as best seen in relation to the rear support 339 part,
against the force of the weaker counterspring 360. This movement
causes structure 361 on the conveyor 351 to affect tapering surface
345 on penetration head 342 to displace the rear part of
penetration head 342 laterally and out of engagement with
penetration drive spring 341. Carrier 330 with connected parts is
now influenced only by force from the return springs 336. In FIG.
3H the return springs 336 has moved the carrier 330 rearwards to
the needle hidden position for the syringe 320. Together with the
carrier 330 also the injection mechanism 350 and the penetration
head 342 has moved rearwards. In FIG. 3I cocking handle 359 has
been pressed rearwards to move injection head 355 against injection
drive spring 354 into a cocked position and head hook 353 again
flex back to retain the injection head 355 in this position. The
cocking movement also acts to compress penetration drive spring 341
via pusher 362 and make trigger 344 lock against housing 310. A
ratchet mechanism (not shown) is arranged to disconnect the damper
at rearward movements between injection head 355 and conveyor 351
to facilitate the cocking operation. In FIG. 3J the cocking handle
359 has been released, conveyor 351 and injection head 355 has
returned to their initial positions with respect to carrier 330,
thereby separating structure 361 and tapering surface 345, allowing
the rear part of penetration head 342 to flex laterally into
engagement with penetration drive spring 341. The device is now
ready for cycle repetition and the syringe has been removed for
replacement.
[0036] FIG. 4 illustrates a modification of the device of FIG. 3,
which is identical in all aspects except that the rotational damper
in the embodiment of FIG. 3 has been replaced with a linear viscous
damper. As in FIG. 3 the autoinjection mechanism 450 comprises a
conveyor 451 (but no toothed rail), a head hook 453, an injection
drive spring 454 and an injection head 455. The linear damper,
generally designated 470, comprises a cylinder 471, here showed as
an integral part of the injection head 455, and a piston 472
attached to a plunger 473, which is attached to the conveyor 451
base at 474. A closure 475 with sealing for the plunger 473 closes
the interior of the damper 470, containing an oil for controlled
damping in flow restrictions in or around the piston 472. The
piston also incorporates a one way valve arrangement (not shown)
allowing undamped movement during the cocking procedure. The damper
cylinder 471 is inserted, and utilizes the space, within the
helical injection drive spring 454. The damper 470 operates in the
same manner as that described in relation to FIG. 3, i.e. its
cylinder/piston parts only move when injection head 455 moves
relative conveyor 451 and performs a damping action only for
forward injection head movements whereas the one way valve
arrangement disconnect damping at rearward movements of the
head.
* * * * *