Safety syringe abstract
Universal safety syringe having a protective cap, a cylinder, a
plunger and a cannula mounted on a cannula base, it being the case
that the cannula base is designed such that it can be pushed firmly
against a stop in the protective cap, that the protective cap, which
can be pushed externally onto a cone, corresponding to a Luer cone,
of the cylinder, is provided with a narrowed section, which is provided
on the inside of the cap, in front of a recess designed for receiving
the cannula base, and delimits the push on travel, that a recess
which receives a cannula base is provided with an undercut which
prevents the cannula base from being removed in the forward direction,
and with an undercut of which the effect can be overcome by the
cone being widened from the inside and which is provided for safeguarding
the cannula stop from being pushed in unintentionally during insertion
of the syringe, and it also being the case that the plunger is designed
with a section which widens the cone cylindrically and with a mushroom-shaped
plunger head, which comes into pulling contact with the needle stop.
A preferred embodiment provides a safeguard against the plunger
being unintentionally pushed in too early and too far.
Safety syringe claims
Having thus described the invention, what is claimed and desired
to be secured by Letters Patent is:
1. A universal safety syringe having a cylinder, a center axis
of the cylinder, a projecting member attached to an end of the cylinder
and defining a recess, a plunger inserted within the cylinder and
moveable along the center axis, a cannula base inserted within the
recess, a cannula mounted on the cannula base and a protective cap
for covering the cannula, the cannula base and the projecting member,
the improvement comprising:
(a) a first undercut formed proximal to a top portion of the projecting
member recess prohibiting the cannula base from being unintentionally
removed during removal of the syringe from an insertion destination,
(b) a second undercut formed proximal to a bottom portion of the
projecting member recess prohibiting the cannula base from being
unintentionally pushed into the cylinder during insertion of the
syringe into the insertion destination,
(c) a mushroom-shaped plunger head capable of entering cavity formed
in the cannula base, the plunger having a lower portion for resting
against a third undercut once the plunger head has entered the cavity,
(d) the projecting member having a conical shape,
(e) the protective cap having a first, second and third section,
the first section having a greater diameter about a mid-section
than the second section and having a conical shape, the second section
having a greater diameter than the third section, the first section
covering the conical-shaped projecting member, the second section
covering the cannula base and the third section covering the cannula,
(f) a first stop member of the cannula base,
(g) a second stop member of the protective cap, the first and second
stop members juxtaposed when the protective cap is completely inserted
over the cannula,
(h) an expansion section attached below the mushroom-shaped plunger
head for widening a lower portion of the projecting member and permitting
the cannula base to fall inwardly within the cylinder by the force
of gravity,
(i) a plurality of lugs located proximal to an actuating end of
the plunger, the plurality of lugs capable of expanding outwardly
when the plunger is pulled in a direction away from the cannula,
but preventing any inward movement of the plunger prior to pulling
the plunger away from the cannula, and
(j) a plurality of lug supports for retaining the plurality of
lugs in a fixed position essentially along the cylinder center axis
prior to the syringe being filled with a liquid.
2. The universal safety syringe of claim 1 wherein the cavity
formed in the cannula base is essentially cylindrically-shaped.
3. The universal safety syringe of claim 1 wherein the projecting
member, the cannula base and the cannula are axially aligned with
the center axis of the cylinder.
4. The universal safety syringe of claim 1 wherein the projecting
member, the cannula base and the cannula are off-axis from the center
axis of the cylinder.
5. The universal safety syringe of claim 4 further comprising:
(a) a plurality of projecting edges of the plunger and
(b) a plurality of guide groves formed in the cylinder for receiving
the plurality of projecting edges and guiding the plunger through
the cylinder.
6. The universal safety syringe of claim 5 wherein the plurality
of projecting edges include a pair of projecting edges disposed
180 degrees from one another and the plurality of guide grooves
includes a pair of guide grooves disposed 180 degrees from one another.
7. The universal safety syringe of claim 1 wherein a pair of lugs
and a pair of lug supports are employed, the pair of lugs and lug
supports positioned at 180 degrees from another.
Safety syringe description
BACKGROUND OF INVENTION
1. Field of Invention
The invention relates to a universal safety syringe according to
the preamble of the main claim.
2. Description of Prior Art
In the case of a number of safety syringes, as are disclosed, for
example, in German Patent Specification 43 40 082 the injection
cannulas are moved back into the cylinder, after use, in order to
remain there permanently and safely, without there being any risk
of injury, during further handling of the syringe. However, as in
the abovementioned document, a new material is also usually proposed,
in this case an elastomeric material for example, or it is no longer
possible to use the conventional needles with Luer cone.
In other embodiments, for example the version described in U.S.
Pat. No. 5336198 even separate means are proposed for the purpose
of tilting the cannula laterally in the cylinder in order that it
cannot be pushed out again. Unfortunately, all these proposals have
in common a not inconsiderable degree of complexity, which makes
these safety syringes appear expensive and suitable only for special
applications.
Unfortunately, however, there is such a great demand for safety
syringes within the medical profession today that safety syringes
really have to be in constant use. Up until now, the complex geometries
with which the cannulas and/or syringes have been provided has meant
that this has not been possible.
In order, however, for it to be possible for safety syringes with
a retractable cannula to be established for general usage, a necessary
precondition is so-called "downward" compatibility with
material which has been used up until now, so that it is also possible
to fit the wide variety of cannulas which have been available up
until now. Otherwise, it would be necessary for novel cannulas of
all sizes to be provided immediately for all conceivable purposes
and at all use locations, in order to avoid the two systems coexisting
over a transition period--with myriad possibilities of confusion,
and problems with storage of double stocks and differing handling
methods at the same time.
However, since hitherto known safety syringes require their own
cannulas and cannula bases in each case, although it has frequently
not been possible to provide or reproach [sic] the desired variety
of these, it is essential for it to be possible to continue using
the cannulas which have been used up until now.
If, however, use is made of a universal safety syringe with retractable
cannula, careless handling of the plunger may cause the latter to
be pushed forwards in the cylinder, where it comes into contact
with the cannula base before the syringe is actually used. This
can take place, for example, as the cannula is pushed on. It goes
without saying, however, that it is absolutely essential for this
to be avoided because, even during further filling of the syringe,
the cannula base is drawn back (too early) into the cylinder - and
it is precisely in emergency situations that this may initially
go unnoticed.
In the case of hitherto known safety syringes, for example those
in DE 38 44 150 this has been avoided by safety elements which
were removed prior to injection, in order for it to be possible
for the plunger to be pushed right in. For universal usage, however,
separate safety elements are highly undesirable since they not only
increase the costs of the syringes, but also render handling of
the syringes for hitherto conventional usage more complex.
SUMMARY OF THE INVENTION
According to the invention, then, the disadvantages of the prior
art are eliminated by a universal safety syringe having the features
of the main claim. Advantageous embodiments of the invention can
be gathered from the subclaims.
It is advantageous, in particular, that, in contrast to conventional
syringes, the safety syringe does not have any additional part,
and it is thus not only the case that the novel safety syringe constitutes
the most cost-effective safety syringe solution, but also that the
movements involved in handling it are exactly the same as those
for handling the conventional syringe. All conventional cannulas
can be fitted by way of the outer Luer standard cone provided. Since
the principle does not require a prefitted cannula, it is also possible,
however, for appropriate (safety) cannulas on their cannula bases
to be selected and inserted just prior to use.
The safety syringe described thus corresponds both to DIN 13098
and to ISO 7886. It is advantageous, in particular, that, in a preferred
embodiment, a premature pushing-down action, which could render
the syringe unusable, is not possible. In the case of an eccentric
cone arrangement, a guide groove or, as proposed, two guide grooves
located opposite one another can make it possible to use, for this
case as well, the principle according to the invention, which, moreover,
is suitable not only for all syringe sizes, but also for two-part
and three-part syringes with an additional elastic plunger seal
at the end of the plunger.
The universal safety syringe according to the invention is distinguished
by a cannula base which is pushed firmly against a stop in the protective
cap, and also [lacuna] a protective cap which can be pushed externally
onto a cone, corresponding to a Luer cone, of the cylinder, there
being provided on the inside of the cap, in front of a recess designed
for receiving the cannula base, a narrowed section which delimits
the push-on travel.
The recess which receives the cannula base [lacuna] provided with
an undercut which prevents the cannula base from being removed in
the forward direction, and with an undercut of which the effect
can be overcome by the cone being widened from the inside and which
is provided for safeguarding the cannula base against being pushed
in unintentionally during insertion of the syringe, this latter
undercut being widened by a cylindrical end of the plunger during
the final advancement stage, while a preferably mushroomshaped plunger
head is pushed into an essentially cylindrical cavity with border
elements engaging behind the mushroom-shaped head.
A further advantageous configuration is distinguished by lugs which
are provided at the actuating end of the plunger, are prestressed
outwards and, prior to the filling operation, are retained, by corresponding
lug supports on the plunger, in a position in which they are aligned
essentially along the syringe axis, in order thus to prevent the
plunger from being pushed into the cylinder.
Said lugs are designed, for example, as two spreader lugs which
are located essentially opposite one another, are fastened at the
actuating end of the plunger by film hinges, are oriented towards
the cylinder and are initially clamped in a recess, provided at
the introduction opening for the plunger, in the cylinder opening
for the introduction of the plunger.
Even in the case of an eccentric arrangement of the cone and of
the plunger head which grips the cannula holder, the invention can
be applied in that the plunger is additionally guided by way of
projecting edges in corresponding guide grooves on the inside of
the plunger [sic].
DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention can be gathered
from the following description of a preferred exemplary embodiment
with reference to the attached drawing, in which:
FIG. 1 shows, in a two-part syringe, the inventive combination
of the cannula base in the tip of the cylinder with the protective
cap having been pushed on and without the plunger head having been
pushed in,
FIG. 2 shows an illustration corresponding to FIG. 1 with the plunger
head having been pushed in and without the protective cap,
FIG. 3 shows a three-part syringe in an illustration corresponding
to FIG. 1
FIG. 4 shows a three-part syringe in an illustration corresponding
to FIG. 2
FIG. 5 shows a further preferred exemplary embodiment of the syringe
according to the invention with the clamping lugs still mounted
in the cylinder,
FIG. 6 shows the illustration of FIG. 5 with the plunger having
been pushed in and the clamping lugs having been displaced outwards,
and
FIG. 7 shows the closed position with the plunger having been drawn
out again,
FIG. 8 shows an illustration of an eccentric cone arrangement,
and
FIG. 9 shows a cross section through the plunger, in which it is
possible to see the guide grooves.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The syringe illustrated in FIG. 1 is provided with a protective
cap 1 which is clamped on a cannula base 2 and, by way of a collar
1a (FIG. 3), fits on a cone on the cylinder which corresponds to
the Luer standard. This collar 1a serves, at the same time, as a
guide for the introduction of the cannula base 2 when the latter
is introduced into the cylinder 3. It protects the cannula base
against damage and contamination prior to the introduction.
The cannula base 2 is provided with a stop 2a, which strikes against
a corresponding stop of the protective cap 1 when the cannula for
the universal safety syringe is fitted. As a result, the protective
cap 1 additionally serves as a stop when the cannula base is introduced
into the cylinder, in that the position of the cannula base 2 in
the cylinder 3 is determined by the protective cap striking against
the cylinder at a further stop 3a.
The cylinder 3 is advantageously provided with an undercut 3b which,
at the preselected push-in depth, engages behind a corresponding
reduction in diameter of the cannula base 2 and thus safeguards
against the cannula being drawn out in a forward direction once
it has been pushed in. On the other hand, however, a further undercut
3c is also provided as a base in the opposite direction and prevents
the base from being pushed in further when the cannula is inserted.
However, this base is not as wide as the abovementioned base, but
rather is dimensioned precisely such that when an end piece of the
plunger, which widens the cylinder slightly at this location, is
pushed in, it makes it possible for the cannula base 2 to be drawn
inwards, through the widened opening, into the plunger.
There may be additionally provided between the cannula base and
cylinder one or more sealing lips 3d, which seal the base at this
location.
In FIG. 4 4c designates the cylindrical part of the plunger which
expands the cylinder beneath the seat of the cannula base in order
to make it possible to overcome the effect of the undercut 3c when,
once a medicament has been discharged, the syringe is to be rendered
unusable by the cannula being drawn in. A small amount of play is
left between the undercut 2b provided in the cannula base and the
plunger head which is introduced here, but this play is sufficient
to allow the cannula, in the drawn-back state, to drop to the side
under the action of gravity, and thus to be prevented from being
able to be pushed out through the same opening again.
Additionally proposed in a preferred embodiment of the invention
illustrated in FIGS. 5 and 6 are two lugs 4a which are provided
at the actuating end of the plunger by a film hinge and are latched
in a corresponding, for example annular, recess at the open grip-plate
end of the cylinder. Provided that the plunger 4 is not moved out,
the lugs will remain in a state in which they are stressed outwards,
by virtue of their film-hinge prestressing, in the annular recess.
If, however, the plunger is drawn back, they will be reliably displaced
further outwards, with the result that, when the plunger is pushed
in again, they rest flatly on the grip plate, on the outside of
the cylinder, rather than returning into the recess again. As a
result, the plunger can be pushed in right to the base of the cylinder
in order to penetrate into the cannula base by way of the plunger
head and to carry said base along with it during a subsequent rearward
movement. Prior to a first rearward movement of the plunger, however,
forces of virtually any strength can be exerted on the plunger without
the latter moving into the stem of the cannula.
Finally, FIG. 8 illustrates an eccentric cone 3e which, nevertheless,
can easily be provided with a cannula base in the same way if the
plunger is designed in a rotationally fixed manner, for example,
by two projecting edges which are guided in corresponding guide
grooves 3g [sic] on the inside of the plunger [sic].
In conclusion, all that remains to point out is that the only difference
between the embodiments of FIGS. 1 and 2 and those of FIGS. 3 and
4 is an additional elastic sealing ring, which is positioned at
the end of the plunger, on the outside, around a corresponding sealing-ring
support.
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