Safety syringe abstract
A single-use safety syringe comprising an outer cylindrical body
provided with an end spout, a needle provided with a joint adapted
to releasably engage the inner wall of the end spout, and a plunger
provided with a fore end adapted to releasably inwardly engage the
joint of the needle so as to allow the plunger to move into the
syringe and engage the end spout to make the injection. The joint
has an inner seat with a widening plug projecting downwardly from
a base of the seat and projections extending from walls of the seat.
The fore end of the plunger has a conical axial cavity open at a
frontal face of the fore end and cuts along its generatrix and a
groove there around. The outer dimension of the fore end corresponds
to the inner dimension of the inner seat of the joint whereby when
the plunger is at the end of the injection the widening plug enters
the cavity and forces walls of the cavity to spread and exert radial
pressure against inner walls of the joint, with the grooves of the
fore end engaging projections of the joint to lock the needle and
plunger together thereby preventing reuse of the needle.
Safety syringe claims
I claim:
1. A single-use safety syringe comprising an outer cylindrical
body (100) provided with an end spout (102), a needle (109) provided
with a joint (110) adapted to releasably engage the inner wall of
said end spout, and a plunger (106) provided with a fore end (108)
adapted to releasably inwardly engage said joint of the needle so
as to allow the plunger to move into the syringe and engage said
end spout (102) to make the injection, said joint (110) having an
inner seat with a widening means (114) projecting downwardly from
a base of said seat and projections (112) extending from walls of
said seat, said fore end (108) of said plunger (106) having a conical
axial cavity (119) open at a frontal face of fore end (108), longitudinal
cuts (118) along its generatrix and external grooves (113) around
the fore end (108), the outer dimension of said fore end (108) corresponding
to the inner dimension of said inner seat of joint (110) whereby
when the plunger (106) is at the end of the injection the widening
means (114) enters the cavity (119) and forces walls of said cavity
to spread and exert radial pressure against inner walls of said
joint (110), grooves (113) engaging projections (112) to lock the
needle and plunger together thereby preventing reuse of the needle.
2. The syringe of claim 1 wherein the end spout (102) defines
interiorly longitudinal grooves (103) and interiorly circumferential
projections (104), and wherein the needle (109) defines radially
exterior tabs (116) and coupling of needle (109) with end spout
(102) retains needle (109) in an operative position while permitting
plunger (106) to be disengaged from needle (109).
3. The syringe of claim 1 wherein an outside surface of joint
(110) and an interior surface of end spout (102) are knurled.
4. The syringe of claim 2 wherein an outside surface of joint
(110) and an interior surface of end spout (102) are knurled.
Safety syringe description
BACKGROUND OF THE INVENTION
The present invention relates to a single-use syringe provided
with a retractile needle and a self-locking device preventing the
syringe from being filled again after the first injection.
As known it is of foremost importance to solve safety problems
linked with the undue or irresponsible handling of used syringes,
both for the contact risks with the used needle and for the contagious
danger involved in a repeated use of the same syringe.
Recently, several syringes have been developed which show the use
of retractable needles, and devices to prevent their re-use. However,
the structure of these syringes is too elaborate and too expensive
to manufacture.
This invention seeks to provide a solution to the above mentioned
problem by means of a syringe providing ease of use, protection
and inaccessibility of the needle once having made the injection.
SUMMARY OF THE INVENTION
According to the invention there is provided a syringe comprising
a cylindrical body provided with a fore end, a plunger sliding in
said cylindrical body, a needle receivable in said cylindrical body,
said needle moving under control of the plunger from an operative
position, in which it is integral with the fore end of the syringe,
and projects therefrom, to a protected position where it is locked
in said cylindrical body. The locking of the needle both to the
body of the syringe and the plunger is made easy and reliable, and
above all the syringe is prevented from being used again after the
first injection.
This has been achieved by providing the base of the needle with
self-engaging means which at the end of the first injection, when
the plunger is at the end of its stroke, locks automatically and
unreleasably the needle to the plunger and constrains it to enter
the body of the syringe again if the plunger is retracted.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be now described with reference to the annexed
drawings showing preferred embodiments of the invention as illustrative
non-limitative examples.
In the drawings:
FIG. 1 shows the syringe according to the invention with the needle
releasably engaging the plunger ready to be moved to the operating
position;
FIG. 2 shows the syringe after the first injection;
FIGS. 1a, 1b and 1c are sectional views respectively of the needle
base, of the end spout and of the syringe's fore end;
FIG. 3 shows in an enlarged scale the syringe with the extracted
needle ready for use and the plunger at the beginning of the filling;
FIG. 4 shows a different embodiment of the device preventing the
syringe from being re-used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to FIG. 1 numeral 100 designates a body of a syringe
of proper size and suitable material which is provided with a fore
end or cylindrical spout 102 opened outwardly and provided with
inner longitudinal grooves 103. At the other end, body 100 carries
the hold flange 105.
Sliding within body 100 of the syringe is a plunger 106 having
a thumbpush 107 and disc 25 carrying a rubber gasket 124 abutting
against a disc 125 integral with a generally cylindrical fore end
108. Fore end 108 is provided with a cavity 119 and radial cuts
118 allowing the fore end to be opened like a corolla.
The third member of FIG. 1 is a needle 109 integral with a joint
or base 110 having outer dimensions corresponding to the inner cavity
of projection 102. Base 110 is provided inside with a seat 111 the
size of which corresponds to the fore end 108. Formed on the inner
walls of seat 111 (FIG. 3) are projections or teeth 112 intended
to engage corresponding notches or grooves 113 formed on fore end
108. Seat 111 communicates with needle 109 through a conical projection
114 hanging from socket 115 at the base of needle 109. Socket 115
is provided with tabs 116 radially projecting and facing grooves
103 and projections 104 in spout 102. Projecting tabs 116 and the
corresponding projections 104 are three in number but it is evident
that this number may be varied.
In operation, the syringe appears as in FIG. 3 needle 109 being
integral with the body 100 of the syringe, plunger 106 being retracted.
This position is reached by first, pushing forward plunger 106 which
fore end 108 is already releasably positioned into the base of the
needle 109 as shown in FIG. 1 so that the needle can project from
fore spout 102 and tabs 116 can slide in grooves 103 whereupon
the plunger is rotated clockwise or anticlockwise so that tabs 116
can abut against and be retained by projections 104. In such a position
the syringe is ready to be filled by sucking in the substance to
be injected, i.e. moving back the plunger easily disengageable from
the needle already locked.
During the injection plunger 106 is pushed forward up to the end
of the stroke and the conical projection 114 of the needle enters
fore end 108 of the plunger and spreads apart the walls thereof
so that notches or grooves 113 engage teeth 112 of base 110 of the
needle which is now integral with the plunger, thus preventing the
syringe to be filled up again. Thereafter the plunger is now rotated
anticlockwise or clockwise to disengage tabs 116 from projections
104 so that needle 109 can return within body 100 of the syringe
under safety conditions. Now plunger rod 106 can be broken at its
predetermined break point designated by 117 in FIG. 2 and needle
109 remain locked in its position inaccessible from the outside.
The outer surface of socket 115 and the inner surface of spout
102 can be knurled to increase the adherence between needle and
spout of the syringe.
In FIG. 4 an alternative solution of the above described coupling
base between needle and plunger is shown. In FIG. 4 the widening
member is suitably shaped to engage a corresponding seat formed
in fore end 108.
This invention has been shown and described according to a preferred
embodiment but it should be understood that construction modification
can be made without parting from the scope of this industrial invention. |