Safety syringe abstract
An automatic safety syringe comprising a syringe body, hollow on
the side and open at the front and rear; and a plunger sliding inside
the syringe body with an injection stroke extending from a retracted
syringe-filling position to a forward syringe-emptying position,
the plunger being provided at the rear with a shaft that can be
operated manually and brought out of the syring body through the
rear end thereof. An injection needle integral with a needle carrier
is egageable with the fore end of the syringe body. A hooking device
is connected to the shaft of the plunger, to hook the needle carrier
when the shaft is at the end of the injection stroke. An automatic
device causes automatic retraction of the shaft of the plunger when
the injection has been completed. a locking device is operatively
connected to the shaft to block forward movement thereof when it
is in the retracted position after intervention of the automatic
device.
Safety syringe claims
What is claimed is:
1. A disposable syringe comprising: a syringe body having a hollow
inside and having a front and rear that are open, a plunger sliding
inside the syringe body and being movable from a retracted syringe-filling
position to a forward syringe-emptying position, said plunger being
provided at the rear with a shaft that can be operated manually
and brought out of the syringe body through the rear end thereof,
an injection needle integral with a needle carrier attachable, directly
or by means of supporting body to the fore end of the syringe body,
hooking means operatively connected to said shaft of the plunger,
able to hook said needle carrier to pull it inside the syringe body,
elastic means retained under compression within said syringe body,
retaining means operatively connected to said syringe body to retain
said elastic means under compression, and engagement means operatively
connected to said shaft able to cooperate with said retaining means
to free said elastic means when said plunger has reached the end
of the injection stroke, so that said elastic means can act on said
shaft to cause retraction thereof into the retracted position, and
locking means operatively connected to said shaft to block forward
movement of said shaft, when it is in the retracted position, after
the injection has been performed, said locking means comprising
flexible longitudinal tongues, and the inside of said syringe body
having an abutment surface constructed to abut against the end of
said tongues of the shaft, when said shaft is in the retracted position
after the injection has been performed, to prevent a possible forward
movement of said shaft.
2. A syringe according to claim 1 characterized in that said shaft
comprises at least two longitudinal walls, disposed in diametrically
opposite positions, and that said tongues are obtained by means
of incisions on said at least two longitudinal walls.
3. A syringe according to claim 1 characterized in that said end
of said tongue protrudes slightly outward with respect to the peripheral
edge of said shaft and that said tongues are inwardly flexible,
so as to bring the end of each tongue within the lateral bulk of
the shaft, when the shaft is inside said chamber of the syringe
body.
4. A syringe according to claim 1 characterized in that said abutment
surface for said longitudinal flexible tongues of the shaft, is
obtained by means of a rear part of the syringe body having an inside
diameter slightly greater than the inner chamber of the syringe
body.
5. A syringe according to claim 4 characterized in that said elastic
means are disposed inside said rear part of the syringe body and
said retaining means for the elastic means are elastic retaining
tongues formed in said rear part of the syringe body.
6. A syringe according to claim 5 characterized in that each of
said retaining tongues is obtained by means of two longitudinal
incisions formed at the end of said rear part of the syringe body
and said retaining tongues comprise an inwardly protruding part
able to retain said elastic means under compression.
7. A syringe according to claim 6 characterized in that said engagement
means are disposed at the rear end of said shaft and comprise a
tapered annular surface able to cooperate with a tapered surface
of said tongues causing outward bending of said retaining tongues
so as to free an end of said elastic means retained by said protruding
part of the retaining tongues.
8. A disposable syringe comprising: a syringe body having a hollow
inside and having a front and rear that are open, a plunger sliding
inside the syringe body and being movable from a retracted syringe-filling
position to a forward syringe-emptying position, said plunger being
provided at the rear with a shaft that can be operated manually
and brought out of the syringe body through the rear end thereof,
an injection needle integral with a needle carrier attachable, directly
or by means of supporting body to the fore end of the syringe body,
hooking means operatively connected to said shaft of the plunger,
able to hook said needle carrier to pull it inside the syringe body,
elastic means retained under compression within said syringe body,
retaining means operatively connected to said syringe body to retain
said elastic means under compression, engagement means operatively
connected to said shaft able to cooperate with said retaining means
to free said elastic means when said plunger has reached the end
of the injection stroke, so that said elastic means can act on said
shaft to cause retraction thereof into the retracted position, and
locking means operatively connected to said shaft to block forward
movement of said shaft, when it is in the retracted position, after
the injection has been performed. wherein said needle carrier comprises
first engagement means able to engage directly with the fore end
of the syringe body or with said supporting body able to be secured
to the fore end of the syringe body and second engagement means
able to engage with said hooking means.
9. A syringe according to claim 8 characterized in that said first
engagement means of said needle carrier are a first pair of opposed
tongues and said second engagement means of said needle carrier
are a second pair of opposed tongues and said hooking means are
an annular ridge protruding radially inward, disposed inside a seat
formed at the fore end of said shaft and communicating with the
outside.
10. A syringe according to claim 9 characterized in that said
supporting body for the needle carrier comprises: an inner housing
able to accommodate a cylindrical block of said needle carrier,
a rear edge able to be engaged by grooves formed in the outer surface
of said first pair of tongues so as to retain the needle carrier,
and transverse tongues protruding radially outward, so as to e able
to be received in a thread formed in the inner surface of the syringe
body to allow the supporting body to be screwed into the syringe
body.
Safety syringe description
The present invention refers to an automatic safety syringe.
As is known, a syringe generally comprises a cylindrical body open
at the rear to accommodate a plunger. A needle, hollow on the inside,
is mounted a head end of the syringe body. By retracting the plunger
the liquid contained in a vial is drawn into the syringe body through
the needle. By pressing on the plunger the liquid contained inside
the syringe body is injected, by means of the needle, into the patient's
body.
To comply with safety regulations and to avoid the transmission
of infectious diseases, syringes must generally be used just once
and then discarded. For this reason there is growing demand on the
market for disposable syringes able to prevent further use thereof.
Moreover, syringes generally present drawbacks from the point of
view of safety. In fact, once the syringe has been used, the needle
remains exposed at the head of the syringe body, with the risk of
accidental injuries or needle sticks.
This drawback is overcome in part by European patent EP 0636381
which describes a protective device for syringe needles. In this
case, when the plunger of the syringe reaches the end of its stroke,
the fore end of the plunger shaft catches the needle. When the injection
is completed the user must manually retract the shaft; in this manner
the needle is pulled by the head of the shaft into a safety position
inside the syringe body which avoids accidental needle sticks.
Said solution has problems during hooking of the needle carrier
and has the drawback that the user, having completed the injection,
can forget to carry out retraction of the shaft, leaving the needle
exposed and thus rendering the protective device ineffective.
Patent application PCT WO 99/37345 describes a disposable safety
syringe which provides a needle-covering sleeve axially mounted
on the syringe body and sliding from a retracted position, in which
it leaves the needle exposed to allow injection, to a forward position
in which it completely covers the needle, preventing re-use of the
syringe and acting as a protection against accidental needle sticks.
Once the injection has been completed, the sleeve is automatically
carried in the safety forward position, by means of an automatic
system and without any operating by the user. However, such a solution
presents some problems for the provision and driving of an additional
member, such as a needle-covering sleeve.
The object of the present invention is to eliminate the drawbacks
of the prior art, providing a disposable safety syringe that is
practical, versatile, cheap and simple to make.
Another object of the present invention is to provide such an automatic
safety syringe that is able to prevent further attempts at use.
Yet another object of the present invention is to provide such
an automatic syringe that is extremely safe and able to prevent
accidental injuries or tampering after use thereof.
These objects are achieved in accordance with the invention with
the characteristics listed in appended independent claim 1.
Advantageous embodiments of the invention are apparent from the
dependent claims.
The disposable syringe according to the invention comprises a syringe
body hollow on the inside and open at the front and rear, a plunger
that can slide inside the syringe body so as to be movable from
a retracted syringe-filling position to a forward syringe-emptying
position, and an injection needle integral with a needle-carrier
that can be engaged at the fore end of the syringe body. The plunger
is provided at the rear with a shaft that can be operated manually
and brought out of the syringe body through the rear end thereof.
The syringe comprises an injection needle integral with a needle
carrier that can be engaged directly or by means of a supporting
body at the fore end of the syringe body.
A hooking device is provided such as to hook the needle carrier
in order to pull it into the syringe body, when the plunger reaches
the end of its stroke after the injection has been carried out.
Furthermore an automatic device is provided which allows the shaft
of the piston to be retracted into a retracted position after the
injection has been carried out and after the hooking device has
hooked the needle.
The peculiarity of the invention lies in the fact that locking
means operationally connected to the shaft of the plunger are provided
to block forward movement of the shaft when it is in the retracted
position, after the injection has been carried out and the automatic
shaft retracting device has come into operation.
The advantages of the disposable syringe according to the invention
are evident. In fact, once the injection has been completed, the
hooking device intervenes to hook the needle carrier, the automatic
device to cause retraction of the shaft which pulls the needle inside
the syringe body and the locking device to block any attempt, voluntary
or involuntary, to advance the plunger shaft, which would cause
the needle to re-emerge from the head of the syringe body.
In this manner the needle always remains protected inside the syringe
body, avoiding the risk of accidental needle sticks and the possibility
of re-use of the syringe.
Further characteristics of the invention will be made clearer by
the detailed description that follows, referring to a purely exemplary
and therefore non-limiting embodiment thereof, illustrated in the
appended drawings, in which:
FIG. 1 is an exploded axonometric view illustrating the automatic
safety syringe according to the invention;
FIG. 2 is an enlarged, perspective view illustrating a needle carrier
inserted in its supporting body;
FIG. 3 is a side view of the needle carrier and supporting body
assembly of FIG. 2;
FIG. 4 is an axial sectional view along sectional plane IV--IV
of FIG. 3;
FIG. 5 is an axial sectional view along sectional plane V--V of
FIG. 4;
FIG. 6 is a view partially in axial section, broken off, showing
the supporting body of the needle carrier mounted in the top of
the syringe body;
FIG. 7 is an axial sectional view illustrating the syringe of FIG.
1 assembled;
FIG. 8 is a view like FIG. 7 in which the plunger is in a forward
position near its forward end of stroke at the end of the injection;
FIG. 9 is a view like FIG. 7 in which the injection has been completed
and automatic retraction of the plunger shaft has taken place.
The automatic safety syringe according to the invention, denoted
as a whole with reference numeral 100 is described with the aid
of the figures.
With reference for now to FIG. 1 in particular, the syringe 100
comprises a cylindrical body 1 hollow on the inside, defining a
cylindrical chamber. The body 1 has a flange 3 which protrudes radially
outward. A cylindrical rear part 30 of the body 1 axially open toward
the outside is provided behind the flange 3. As shown in FIG. 7
the rear part 30 has an inside diameter slightly greater than the
inside diameter of the body 1 of the syringe so as to define an
annular abutment surface 31.
In the rear part 30 of the body two longitudinal tongues 32 disposed
in diametrically opposite positions are provided. Each tongue 32
is obtained by means of two longitudinal incisions formed on the
rear part 30 of the syringe body. The tongues 32 are flexible and
can bend outward. Each tongue 32 has an inwardly tapered rear end
34 which defines an inwardly protruding part having an abutment
surface 35 protruding radially inward from the inner surface of
the tongue 32.
A spring 70 is retained inside the rear part 30 of the syringe
body, compressed between the annular abutment surface 31 and the
abutment surface 35 of the tongues 32.
The fore end of the body 1 is tapered and ends with an outwardly
open head 2 in the form of a cylindrical tang, with a smaller diameter
than the body 4. As shown better in FIG. 6 an inner thread 4 is
formed in the inner surface of the head 2.
A needle 10 is supported by a needle carrier 11. As better shown
in FIGS. 4 and 5 the needle carrier 11 comprises a cylindrical
block 12 which has an axial hole to receive an end of the needle
10. The cylindrical block 12 has four flexible tongues comprising
a first pair of opposed tongues 13 and a second pair of opposed
tongues 16. The tongues 13 and 16 are disposed around an axial space
14 and are separated from one another by longitudinal slits of the
space 14.
The two flexible tongues 13 of the first pair have a tapered outwardly
protruding outer end surface 19 that defines an outwardly facing
groove 15. The two flexible tongues 16 of the second pair have a
tapered outwardly protruding end surface 18 which delimits an outwardly
facing abutment surface 17. The tongues 13 of the first pair are
slightly shorter than the tongues 16 of the second pair.
The needle carrier 11 is inserted in a supporting body 20. With
reference to FIGS. 2 and 3 the supporting body 20 has a frustoconical
shape, is hollow on the inside and has a cylindrical housing 21
axially able to accommodate the cylindrical block 12 of the needle
carrier, said housing communicating with an axial channel 22 able
to allow the passage of the needle 10 which emerges axially from
the supporting body 20.
In the vicinity of the rear end of the supporting body 20 two radial
slots 23 are disposed in diametrically opposite positions communicating
with the housing 21 so as to delimit an edge part 25 at the rear
end of the supporting body 20. In front of the radial slits 23 are
two transverse tongues 24 which protrude radially outward from the
outer side surface of the supporting body 20. The tongues 24 have
such a thickness as to be able to engage inside the thread 4 provided
inside the head 2 of the syringe body 1.
As shown in particular in FIG. 4 the needle carrier 11 is inserted
inside the supporting body 20 and in particular the protruding front
part of each tongue 13 engages inside the respective radial slot
23 and the edge 25 of the supporting body 20 engages inside the
two grooves 15 of the two tongues 13. In this manner the needle
carrier 11 is firmly retained and held in an axial position inside
the supporting body 20.
On compressing the tongues 13 inwardly the edge 25 of the supporting
body 20 disengages from the grooves 15 of the tongues 13 and the
needle carrier 11 can be extracted from the supporting body 20.
In this manner the needle carrier 11 is of the interchangeable type
and can be replaced according to the type of needle 10 to be used.
The needle carrier 11 and supporting body 20 assembly is mounted
in the head 2 of the syringe body by screwing. To be precise, the
radial tongues 24 of the supporting body are screwed into the inside
thread 4 of the head 2 of the syringe body. The needle 10 is covered
by means of a needle guard 26 (FIG. 1) which snap engages or screws
into the cap 20.
A plunger 40 is made of plastic or rubber material and is of such
a shape as to be able to slide tightly inside the chamber of the
syringe body 1. The plunger 40 has an axial through cavity able
to receive in engagement a head 51 of a plunger shaft 50.
The shaft 50 comprises an axial body part from which radially extend
four longitudinal walls 54 at right angles to each other, so that
the shaft 50 is substantially cross-shaped in section.
Two longitudinal tongues 57 disposed respectively on two diametrically
opposed walls 54 are provided in the front part of the shaft 50.
Each longitudinal tongue 57 is delimited by a longitudinal incision
55 and a transverse incision 56 on the respective wall 54. In normal
conditions, the tongues 57 protrude slightly outward so that the
end 58 of each tongue 57 defines an abutment surface outside the
bulk of the side profile of the walls 54. The tongues 57 are flexible
and can bend inward when the shaft is inside the chamber of the
syringe body 1 and the tongues 57 are in contact with the inner
wall of the syringe body.
The walls 54 are disposed between the head 51 and a rear flange
80. The rear flange 80 constitutes a resting surface for manual
operation of the shaft of the syringe by the user. The flange 80
has in its front end an annular inwardly tapered surface 81 able
to cooperate with the tapered surface 34 of the longitudinal tongues
32 of the rear part 30 of the syringe body. The tapered surface
81 of the rear flange 80 defines a radial abutment surface 82.
The head 51 has a first annular flange 52 which engages in an annular
seat of the cavity 41 of the plunger and a second annular abutment
flange 53 against which the base of the plunger 40 abuts.
As shown in FIG. 7 the head 51 of the shaft 50 has an outwardly
open cylindrical seat 60. An annular ridge 61 protruding radially
inward is provided inside the cylindrical seat 60. The annular ridge
61 is able to cooperate with the tapered surfaces 19 and 18 of the
tongues 13 and 16 respectively, of the needle carrier 11.
Operation of the syringe 100 according to the invention will now
be described.
In an initial situation the needle carrier 11 is mounted in the
supporting body 20 with the edge 25 of the supporting body 20 engaged
in the grooves 15 of the tongues 13 of the needle carrier 11. The
supporting body 20 is mounted in the head 2 of the syringe body
1. The needle guard 26 is mounted on the supporting body 20 and
keeps the needle 10 covered. The spring 70 is under compression
inside the rear part 30 of the syringe body 1. The plunger 40 is
mounted on the head of the shaft 50 and is inside the chamber of
the syringe body 1. The longitudinal tongues 57 of the shaft 50
being in abutment with the inner surface of the chamber of the syringe
body, are elastically bent inward.
Initially, the needle guard 26 is extracted, the needle 10 is positioned
in the liquid to be aspirated, and the user retracts the shaft 50
by means of the operating flange 80 of the shaft 50. The consequent
retraction of the plunger 40 causes a vacuum in the chamber of the
syringe body 1 thus the liquid is drawn into the chamber of the
syringe body 1 through the needle 10 and the syringe is substantially
in the configuration shown in FIG. 7. Obviously the syringe could
alternatively be pre-filled.
When the injection is performed, the user presses the rear part
80 of the shaft 50 causing a forward movement of the plunger 40
which pushes the liquid that is injected through the needle 10.
As shown in FIG. 8 when the plunger 40 arrives in the vicinity
of the end of its stroke, the tapered end parts 19 and 18 of the
tongues 13 and 16 respectively, of the needle carrier 11 enter
the seat 60 of the head 51 of the shaft and come into contact with
the annular ridge 61 provided inside the seat 60.
In particular, the outer tapered surface 18 of the tongues 16 and
the outer tapered surface 19 of the tongues 13 slide on the annular
ridge 61 and consequently the tongues 16 and the tongues 13 bend
inward. When the plunger 40 reaches the end of its stroke, the annular
ridge 61 passes the tapered outer surface 18 of the tongues 16.
Consequently the tongues 16 snap outward and the abutment surface
17 of the tongues 16 engages with the annular ridge 61 of the head
of the shaft. In this condition, the needle carrier 11 is hooked
by the head of the shaft.
The tongues 13 also, sliding on the annular ridge 61 bend inward
and, when the plunger has reached the end of its stroke, the grooves
15 of the tongues 13 disengage from the edge 25 of the supporting
body 20. In this condition the needle carrier 11 is hooked to the
head of the shaft and is no longer retained by the supporting body
20 which is integral with the head 2 of the syringe body.
When the plunger 40 is at the end of its stroke, the tapered surface
81 of the rear flange 80 of the shaft abuts against the tapered
surface 34 of the end of the tongues 32 of the rear part 30 of the
syringe body. Consequently the tongues 32 bend outward and one end
of the spring 70 is no longer retained by the retaining surface
35. As a result the spring 70 which was compressed, is released
and its free end abuts against the abutment surface 82 of the rear
flange 80 causing automatic and involuntary retraction of the shaft
50.
Since the needle carrier 11 is constrained to the head 51 of the
shaft 50 when the spring 70 causes retraction of the shaft 50
the needle 10 is pulled inside the chamber of the syringe body by
the needle carrier, as shown in FIG. 9.
During automatic retraction of the shaft 50 when the free end
58 of the longitudinal tongues 57 of the shaft 50 goes beyond the
abutment surface 31 inside the syringe body 1 substantially level
with the flange 3 of the syringe body, the longitudinal tongues
57 bend outward, within the rear part 30 of the syringe body.
In this situation forward movement of the shaft 50 can no longer
be caused, since the ends 58 of the tongues 57 would abut against
the abutment surface 31 of the inner wall of the syringe body, preventing
any attempt to push the shaft 50 forward. In this manner the needle
10 always remains protected inside the chamber of the syringe body
and possible injury or attempts to re-use the syringe are avoided.
Numerous changes and modifications of detail within the reach of
a person skilled in the art can be made to the present embodiment
of the invention without departing from the scope of the invention,
set forth in the appended claims. |