A single use disposable syringe having a piston axially slidable
in a barrel for undergoing a retraction movement to fill the barrel
with fluid and a forward movement to discharge the fluid from the
barrel. An operating rod projects from the barrel for operating
the piston and the rod is operatively connected to the piston with
capability of relative axial movement therebetween to approach the
piston during its forward movement. A flexible finger has one end
connected to the piston or rod and a cutting element is provided
on the flexible finger in spaced relation from the connected end
thereof and facing the barrel. During retraction movement of the
piston, the cutting element is retracted from the barrel whereas
during forward travel of the piston and approach of the operating
rod towards the piston, a deviation member displaces the flexible
finger outwardly to produce cutting of the barrel by the cutting
element to render the barrel subsequently unusable.
1. A singe use disposable syringe comprising:
a barrel having an axis,
a piston member axially slidable in said barrel in a retraction
movement to fill the barrel with fluid and a forward movement to
discharge fluid from the barrel,
an operating rod member projecting from said barrel for operating
said piston member and being operatively connected to said piston
member with capability of relative axial movement therebetween to
approach said piston member during forward movement of said piston
a flexible finger having an end connected to one of said members,
cutting means on said flexible finger spaced from said one end
thereof and facing said barrel, and
deviation means for displacing said flexible finger outwardly during
approach of said operating rod member towards said piston member
upon forward movement of said piston member to produce cutting of
said barrel by said cutting means to render said barrel subsequently
unusable, said flexible finger having a normal position, when not
displaced by said deviation means, in which said cutting means is
retracted from said barrel during retraction movement of said piston
2. A syringe as claimed in claim 1 wherein said deviation means
comprises an oblique ramp having an inclined surface contacting
said flexible finger to move said finger towards said barrel when
said operating rod member and said piston member approach one another.
3. A syringe as claimed in claim 1 wherein said deviation means
comprises a body have a conical surface contacting said flexible
4. A syringe as claimed in claim 1 comprising a second flexible
finger and corresponding cutting means on said one member in diametric
opposition to the first said flexible finger.
5. A syringe as claimed in claim 1 wherein said deviation means
comprises a conical surface slidably emerging said finger member.
6. A syringe as claimed in claim 1 comprising means coupling the
rod member and the piston member for relative axial movement, comprising
a piston rod on said piston member and a head on said piston rod,
said rod member have a housing in which said head is slidable and
catch means retaining said head in said housing.
7. A syringe as claimed in claim 1 wherein said deviation means
comprises an articulated connecting rod joining said piston and
rod members to permit limited relative axial movement thereof, said
articulated connecting rod being connected to said flexible finger
to produce outward displacement thereof when the piston and rod
members approach one another.
8. A syringe as claimed in claim 1 wherein said barrel is constituted
of a breakable material, said cutting means comprising a barrel
member which breaks said barrel when displaced thereagainst.
9. A syringe as claimed in claim 1 comprising an elastic pin with
flexible arms each constituting one said flexible finger.
10. A syringe as claimed in claim 1 wherein said barrel has a
zone of minimum resistance facing said cutting means.
11. A syringe as claimed in claim 1 wherein said barrel is cylindrical
and has a zone of minimum resistance facing said cutting means extending
along a generatrix of said barrel.
12. A syringe as claimed in claim 11 comprising a tongue on said
barrel covering at least a portion of said zone of minimum resistance.
13. A syringe as claimed in claim 1 comprising a bead on said
barrel engaging said rod member to permit sliding movement of said
rod member in said barrel while preventing relative rotation between
said rod member and said barrel.
14. A syringe as claimed in claim 13 comprising flange means on
said operating rod member cooperating with said bead for limiting
the movement of said rod member in said barrel.
15. A syringe as claimed in claim 14 comprising removable stop
means interposed between said operating rod means and said barrel
to temporarily block relative movement therebetween.
16. A syringe as claimed in claim 1 comprising means for limiting
outward movement of said flexible finger to prevent said cutting
means from extending outwardly of said barrel.
1. Field of the Invention
The present invention relates to disposable syringes which are
rendered non-reusable after a first injection therewith.
2. Background and Prior Art
Syringes disposable after a single use are being used more and
more to avoid the risks of contamination from using a syringe poorly
sterilized after a first use.
However, contaminations are due to the use by drug-addicts of previously
used syringes which are not sterilized or poorly sterilized.
In order to avoid such accidents, syringes have been proposed which
are rendered automatically non-usable after a first injection.
U.S. Pat. No. 3 934 586 (Easton et al) describes pre-filled syringes
which make it possible to inject several successive doses.
The operating rod of these syringes bears stops which abut one
another on the end of the barrel and which are broken along an oblique
line of maximum weakness which leaves a sharp edge which scores
the wall of the barrel. Such syringes cannot be re-used.
Patent De-A-1 965 761 FR-A-2 027 681 U.S. Pat. No. 3 667 657
(Chiquiar-Arias) describe pre-filled syringes which comprise a small
knife which is fixed laterally on the operating rod and which is
engaged in an opening in the cylindrical barrel. These syringes
cannot be sold empty to be filled by the user as, as soon as the
piston is driven into the barrel, the knife cuts the latter.
U.S. Pat. No. 3 951 146 DE-A-2 354 628 FR-A-2 204 429 (Chiquiar-Arias)
describes syringes in which the operating rod bears a casing or
a notch in which is housed a small knife which is pushed radially
by a spring and which presents a rounded rear edge and a cutting
front edge. It is possible to withdraw the piston rearwardly in
order to suck liquid into the barrel without scratching the wall
of the barrel. In order to drive the piston to the bottom of the
barrel, a protection sheet is engaged between the wall of the cylindrical
barrel and the cutting blade which is removed thereafter.
The problem to be solved is to provide self-destroying syringes
which may be sold empty and which make it possible firstly to drive
the piston in the barrel in order to drive out the air without scratching
the barrel, then to withdraw the piston rearwardly in order to suck
in a liquid without scratching or cutting the wall of the barrel,
then to drive the piston again into the barrel in order to inject
the dose of liquid contained therein, while cutting or scratching
or breaking the wall of the barrel in order to render the syringe
unusable a second time.
SUMMARY OF THE INVENTION
A syringe according to the invention comprises a cylindrical barrel,
a piston displaceable inside said barrel, a rod for moving said
piston and a cutting member which scratches or cuts or breaks the
wall of said barrel during the injection of the liquid contained
in said barrel.
The solution of the aforesaid problem consists in a syringe in
which one end of the rod and said piston are connected by means
which allow a relative axial displacement and either the rod or
piston bears at least one flexible finger, which bears at its free
end a cutting member, whilst the other bears a deviation means which
cooperates with said flexible finger to deform the latter by pushing
said cutting member outwardly when said end of the rod and said
piston approach one another, with the result that, when the rod
is withdrawn rearwardly in order to fill the syringe with the liquid
to be injected, said flexible fingers occupy a position in which
said cutting members are retracted inside said barrel and do not
touch the wall thereof and when said piston is driven into said
barrel, pushing on the rod to inject the liquid, said flexible fingers
move apart and said cutting members are pushed outwardly and cut
or scratch the wall of the barrel, which renders the syringe unusable
a second time.
According to a first embodiment, said piston or one end of the
rod bears one or more ramps inclined with respect to the axis of
the syringe against which said flexible fingers slide, moving apart
towards the outside when the rod and said piston approach each other
axially and retracting towards the inside when the rod and said
piston approach each other axially and retracting towards the inside
when the rod and said piston move apart axially from each other.
According to another embodiment, each of the flexible fingers is
connected to the piston or to one end of said rod by an articulated
connected rod which pushes said flexible finger outwardly when said
piston and said rod approach each other axially and which returns
said flexible finger inwardly when said piston and said rod move
apart axially from each other.
A process for manufacturing a non-reusable syringe according to
the invention comprises the following operations:
connecting one end of the rod to said piston by connected means
which allows a relative axial displacement of small amplitude and
providing the rod or piston with at least one flexible finger which
bears a cutting member while the other is provided with a deviation
means which cooperates with said flexible finger in order to move
the finger outwardly when said rod and said piston axially approach
each other and to allow the finger to retract inwardly when said
piston and said rod move axially away from each other;
placing between a flange of the barrel and a disc on the end of
the rod a safety distance piece in order to avoid, in the event
of accidental abutment on the rod during handling, packing or unpacking
of the syringe, piercing of the wall of the barrel, which would
prematurely render the syringe unusable;
connecting the end of said provided with the needle support or
an incorporated needle to a suction means to drive said piston in
said barrel without said cutting members cutting or scratching said
The invention results in novel disposable syringes which cannot
be reused after a first injection.
The syringes according to the invention have the advantage of being
able to be delivered, unfilled, with the piston driven in the barrel
of the syringe, this operation being effected in the factory by
connecting the syringes to a suction means which sucks the piston
towards the bottom of the syringe so that the cutting members are
retracted during this operation and do not risk scratching or cutting
the wall of the barrel.
The syringes according to the invention also have the advantage
that the cutting members are pushed radially by a force which is
proportional to the axial thrust exerted on the rod during injection,
so that the penetration of the cutting members in the wall of the
barrel is better ensured than in the known syringes where the knife
is pushed radially by a spring exerting a constant thrust.
The freedom of relative axial displacement of the rod with respect
to the piston of the syringe makes it possible to obtain a spacing
of the knives towards the outside when one presses on the rod but
also a retraction of the knives towards the inside when the rod
moves axially away from the piston, i.e. when one pulls on the rod
to suck liquid or when the piston is sucked to drive it in the syringe,
with the result that, during these two operations, the cutting members
do not risk cutting or scratching the wall of the barrel.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description refers to the accompanying drawings which
show, without any limiting character, embodiments of syringes according
to the invention.
FIG. 1 shows in axial section a disposable syringe according to
a first embodiment.
FIG. 2 shows in partial axial section the same disposable syringe
according to the invention during use.
FIG. 3 is a transverse section along line III--III of FIG. 2.
FIG. 4 shows in axial section a second embodiment of disposable
syringes according to the invention.
FIG. 5 shows, in partial axial section, the same embodiment as
in FIG. 4 under conditions of use identical to those of FIG. 2.
FIG. 6 shows in axial section a third embodiment of disposable
syringes according to the invention.
FIG. 7 shows in partial axial section the same disposable syringe
FIG. 8 shows in partial axial section a fourth embodiment of disposable
syringes according to the invention.
FIGS. 9 and 10 show steps for carrying out the process of manufacture
according to the invention.
FIGS. 11 12 and 13 show three particular embodiments of the cylindrical
barrel of disposable syringes according to the invention.
FIG. 14 is a section along XIV--XIV of FIG. 11.
FIG. 15 is a section along XV--XV of FIG. 12.
FIG. 16 is a section along XVI--XVI of FIG. 13.
As indicated in FIGS. 1 to 3 a disposable syringe comprises a
cylindrical barrel 1 with axis XXI which is provided at one end
with a needle 2. An operating rod 8 and a piston 6 which slide in
The rod 8 has a groove 11 extending longitudinally and parallel
to the axis, XXI said groove being bounded at one end by a disc
15 and at the other end by a stop 12 connected to rod 8.
The barrel 1 advantageously comprises at one end a flange 5 on
which is added, after positioning the rod 8 in said barrel, a guide
bead 4 which penetrates in said groove.
The bead 4 extends into 11 and groove allows the rod 8 to slide
with respect to said barrel but prevents rotation of said rod with
respect to said barrel.
Said bead 4 has a face 13 which forms a stop, with the stop 12
connected to the rod, 8 with the result that, when an attempt is
made to extract said rod from said barrel, the face 12 comes into
contact with the stop 13 and therefore prevents the extraction.
This prevents the user from removing the cutting members to be
In a preferred embodiment, the wall of said barrel comprises at
minimum one zone 3 of least resistance, for example a groove which
extends along a generatrix of said cylindrical barrel substantially
over the entire length of said barrel.
Said piston advantageously comprises sealing means 7.
The syringe according to the invention comprises at least one pointed
and cutting projection of any other cutting or breaking means 9
such as a blade, sharp edge or knurl 30 adapted to produce grooving,
permanent deformation, cutting perforation or breaking into fragments
of said barrel, with the result that the latter can no longer cooperate
with said piston so as to permit pumping of the fluid, and therefore
it prevents subsequent use of the syringe for the purpose of injecting
In the following specification, in order to facilitate reading
thereof, said means will be designated by the generic term cutting
In the embodiments according to the invention, said cutting members
are mounted at the free end of flexible fingers 10 which are themselves
connected to an end of said rod 8 or said piston 6.
In the embodiment shown in FIG. 3 the syringe comprises two flexible
In the embodiments according to the invention shown in FIGS. 1
2 4 5 6 7 8 9 said flexible fingers are connected to an end
In a first embodiment according to the invention, said piston comprises
at least one deviation surface 16 which is constituted for example
by a truncated surface as shown in FIGS. 1 and 2 or by an oblique
ramp with respect to axis XX.sub.1 against which the fingers come
In FIG. 1 said deviation surface cooperates with said flexible
fingers which occupy a position in which the latter are retracted
inside said barrel and do not touch the wall thereof.
In FIG. 2 said deviation surface cooperates with said flexible
fingers in order to deform them by pushing said cutting members
outwardly when said end of the rod and said piston approach each
other, subsequent to the application of a thrust represented by
arrow P on rod so that said cutting members cut or scratch the wall
of said barrel, which renders the syringe unusable a second time.
Such changes in position of said flexible fingers are due on the
one hand to the flexibility of the fingers and on the other hand
to the relative approach or moving apart of said piston and said
manoeuvring rod, these movement being said possible by the particular
structure of the connecting means between and said piston.
In fact, in this embodiment, FIGS. 1 and 2 show that said piston
comprises a rod 17 and a head 18 which terminates in a face 21
while the opposed end of rod 8 comprises a housing 31 limited by
a bottom face 20 said flexible fingers comprising catches 19.
The flexibility of the fingers makes it possible, when assembling
the syringe, for said head 18 on the piston to penetrate in housing
31 in the rod so that catches 19 engage behind head 18 whereby the
rod and piston are connected with freedom of relative axial displacement.
FIG. 2 shows that such relative axial displacement is limited in
the direction of approach between said rod and said piston, by the
contact of said surface 21 and of said bottom face 20 with the
result that the spacing apart of the flexible finger subsequent
to such approach is thus limited.
Moreover, FIG. 3 shows that said flexible fingers comprise bearing
faces 22 and 23 located in the immediate vicinity of the cutting
members 9 said bearing faces cooperating with the inner wall of
said barrel, thus limiting the spaced apart relationship of said
cutting members, with the result that, during cutting, the cutting
members do not project outside said barrel and cannot injure the
In FIGS. 4 and 5 analogous parts of FIGS. 1 and 2 are shown with
the same references.
FIGS. 4 and 5 show another embodiment according to the invention
in which said flexible fingers 10 are connected at one end to rod
8 and at the other end to said piston 6 via connecting rods 24 articulated
at their two ends, the connecting means between rod 8 and piston
6 thus defined allowing the spacing apart and retraction of said
cutting members corresponding respectively to the relative approach
and spacing apart of said rod and said piston.
In fact, FIGS. 4 and 5 show that said connecting rods 24 comprise
a substantially rigid central part which itself comprises a surface
25 which forms a stop, and two end of a section and rigidity substantially
less than the central part with the result that said ends of the
connected rod which are connected, one to said piston, the other
to said flexible finger, may be deformed and thus constitute an
FIG. 4 shows that, after application of a traction force to rod
represented by arrow F, the forces of traction are transmitted by
said flexible fingers to said connecting rods and by said connecting
rods to said piston.
Taking into account the resistance to sliding of said piston in
said barrel due to the friction of the latter and said sealing means,
the ends of said connecting rods performing the role of articulation
joints on being deformed, said connecting rods move, provoking retraction
inside the barrel of the cutting members simultaneously with the
relative moving apart of said rod and of said piston.
FIG. 5 shows that after the application of a thrust on the rod,
represented by arrow F, the force transmitted by said flexible fingers
lead to a deformation of the ends of the connecting rods 24 to cause
displacement of the cutting members 9 towards the wall of said barrel,
with the result that, when the piston is driven into said barrel,
said cutting members cut or scratch said inner wall of said barrel.
FIGS. 6 and 7 show a third embodiment according to the invention.
The analogous parts of FIGS. 1 and 2 are represented by the same
Piston 6 comprises a rod 17 and a head 18 slidable in a housing
31 arranged at the end of rod 8 which itself comprises catches 27
and a bearing face 28 which allows a relative axial displacement
between the rod 8 and the piston 6.
Inside said piston rod 17 are two inclined surfaces 16 which form
two oblique ramps which converge in the direction of the rod 8.
An elastic pin 38 in the form of a U constitutes a pair of flexible
fingers whose ends are bent and bear cutting members 9.
Said pin is seemed to rod 8 by a connecting means 29 such as a
clamp, ring or any other equivalent fixing means.
In FIG. 6 the surfaces 16 cooperate with said flexible fingers
so that the latter retract inside said cylindrical barrel without
touching the wall thereof, when said piston moves away from said
FIG. 7 shows that, during injection of the liquid under the action
of a thrust by the user on rod 8 represented by arrow P, said deviation
surfaces excert forces outwardly, due to the approach of said piston
and said rod, to cause said cutting members to cut said wall.
In the embodiment shown in FIGS. 6 and 7 the deviation surfaces,
in the form of inclined ramps, may advantageously be constituted
by the bottom of a groove made in said rod 17 the sides of said
groove serving to guide the flexible fingers during the relative
movements between said piston and said rod 8.
FIG. 8 shows a variant according to the invention, in which the
cutting members are constituted by knurls 30 particularly for when
said barrel is made of a breakable material such as glass, plastics
materials of polycarbonate type, which, under the pressure exerted
by said knurls according to the same principles as developed for
the other embodiments, will break into fragments or burst.
In this embodiment, the cylindrical barrel may be covered on the
outside with a supple film which forms a jacket avoiding dispersion
of the fragments resulting from the breakage. The breakage advantageously
occurs in the zone of least resistance 3 constituted by a groove
made in the barrel, said groove being filled with a supple resin
which avoids the dispersion of the fragments resulting from the
FIG. 9 shows the process of manufacturing the disposable syringes
according to the invention and more particularly the process which
consists in guiding said piston in the bottom of said barrel without
damaging the latter and enabling empty syringes ready to be filled
by suction to be delivered.
At least one tube 32 is equipped with a connecting device 33 fixed
on the end of the needle 2 of the syringe.
Tube 32 is connected at its other end to suction means 34 such
as a pump, for example.
The four principal pieces of the syringe, viz. said barrel, said
piston, said rod, said bead, may be manufactured separately.
In that case, said need an said piston is engaged in said housing
provided in said rod.
In a variant, the rod and the piston are assembled together.
Said piston is then presented in said barrel so that the sealing
means 7 are introduced as shown in FIG. 9 taking care to maintain
said rod remote from said piston thanks to the structure of the
connecting means described in the above paragraphs, with the result
that said flexible fingers are in a retracted position and do not
damage said barrel when they are made to penetrate therein.
When said suction means is actuated, said piston is subjected to
a force due to the difference in pressure existing between its faces,
which force produces its displacement towards the bottom of said
barrel: the flexible fingers remain in their retracted position
during this movement. The piston drives the rod in its movement.
Finally, said bead 4 is mounted on said flange and there is placed
between the flange 5 of the barrel and the disc 15 of the end of
the rod 8 as shown in FIG. 10 a safety spacer device 39 in order
to avoid, in the event of accidental pressure on the rod, 8 during
handling, packing or unpacking of the syringe, cutting of the wall
of the barrel before use, which would prematurely render the syringe
FIGS. 11 to 16 show three other embodiments of a syringe according
to the invention in which said barrel comprises said zone of least
resistance 3 which extends along a generatrix of said cylindrical
In an embodiment shown in FIGS. 11 and 14 said wall of said barrel
comprises two projecting zones 35 which extend along two generatrices
of said barrel, on either side of said zone of least resistance
3 and form two beads so that, when said barrel is cut by said cutting
members, said projecting zones prevent any accidental contact between
said cutting members and the user.
FIGS. 12 and 13 show another variant in which said wall comprises
one single projecting zone, in the form of a tongue 36 which partially
covers said zone of least resistance 3.
FIGS. 13 and 16 show a variant according to the invention in which
said projecting zones 35 located on either side of zone 3 join
to form a tongue 37 which completely covers said zone 3.
The embodiments of a syringe according to the invention shown in
FIGS. 11 to 16 make it possible to avoid andy risk of said cutting
members injuring the user.
The relative arrangements of the fingers and the deviation surfaces
with respect to the piston and to the rod may, of course, be reversed
without the operation being modified.