HK1064624A - Improved non-reusable syringe - Google Patents

Description

Improved non-reusable syringe

The present invention relates to syringes and more particularly to single use or non-reusable syringes with automatically retracting needles.

The hazards posed to the general public and medical personnel from used syringe sticks and the problems associated with syringes that are reused by intravenous drug injectors are well documented. There have been numerous attempts in the art to provide syringes that are disposable and self-destruct after use, or to provide protection against needle sticks. One such syringe is disclosed in U.S. patent No. 5,267,976, for example. In general, prior art instruments have one or more drawbacks in that: they are expensive to manufacture, unreliable, messy or rely on the user taking some positive action after the first use to ensure that the syringe is disabled from further use. In prior art devices having an automatically retracting needle, such as the device disclosed in U.S. Pat. No. 5,267,976, there is also the possibility of premature retraction of the needle, such as when the plunger is moved from its sealed position in preparation for drawing medication into the syringe.

It is therefore an object of the present invention to provide a single use syringe with a self-retracting needle that overcomes one or more of the above-mentioned and other disadvantages of known devices.

The present invention provides a syringe comprising: an outer barrel having first and second ends; an inner barrel longitudinally slidable within said outer barrel and adapted to support at one end a needle projecting through an aperture in said first end of said outer barrel, said needle being in fluid communication with a fluid-containing chamber of said inner barrel; and a piston in said fluid containing chamber actuatable to draw fluid into said fluid containing chamber and to inject fluid from said fluid containing chamber through said needle, said piston being connected to an actuating rod extending from the other end of said inner barrel and the second end of said outer barrel. The outer barrel has first and second spaced apart retaining means on an inner wall surface thereof. Said inner barrel having latching means for engaging said first or second retaining means and locking said inner barrel in one of two positions relative to said outer barrel: a first said position when said needle projects from said outer barrel and is in a use position; and, a second said position wherein said needle is fully retracted within said outer barrel. Biasing means is provided for biasing said inner barrel towards said second position. The plunger actuating lever has means for contacting the latch means when the plunger is fully depressed to disengage the latch means from the first retaining position whereby the needle moves to the second position wherein the latch means engages the second retaining means and cannot be re-engaged within the first retaining means.

In order that the invention may be more readily understood, a specific embodiment will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a syringe according to an embodiment of the present invention, shown in an initial position;

FIG. 1(a) is an enlarged view of the portion shown as circle "A" in FIG. 1;

FIG. 2 is a view similar to FIG. 1 but showing the syringe in a first stage of operation;

FIG. 2(a) is an enlarged view of the portion shown as circle "B" in FIG. 2;

FIG. 3 is a view similar to FIGS. 1 and 2 but showing the syringe in a second stage of operation;

FIG. 4 is a view similar to FIGS. 1-3 but showing the syringe in a third stage of operation;

FIG. 4(a) is an enlarged view of the portion shown as circle "C" in FIG. 4;

FIG. 5 is a view similar to FIGS. 1-4, but showing the syringe in a fourth stage of operation;

FIG. 5(a) is an enlarged view of the portion of FIG. 5 shown as circle "D";

FIG. 6 is an exploded perspective view of the syringe of FIGS. 1-5;

FIG. 7 is a view similar to FIG. 1 showing another embodiment of the invention in an initial position;

FIG. 7(a) is an enlarged view of the portion of FIG. 7 shown as circle "E";

FIG. 8 is a view similar to FIG. 7 but showing the syringe in a first stage of operation;

FIG. 8(a) is an enlarged view of the portion of FIG. 8 shown as circle "F";

fig. 9 is a view similar to fig. 7 and 8, showing the syringe in a fourth stage of operation;

FIG. 9(a) is an enlarged view of the portion of FIG. 9 shown as circle "G";

fig. 10 is a view similar to fig. 7-9, showing the syringe in a fifth stage of operation;

FIG. 10(a) is an enlarged view of the portion of FIG. 10 shown as circle "H";

fig. 11 is an exploded perspective view of the syringe of fig. 7-10 (inclusive);

FIG. 12 is a side view of the syringe shown in two particular embodiments;

FIG. 13 is a view similar to FIG. 12 but showing the syringe rotated 90 about its longitudinal axis;

fig. 14 is an enlarged sectional view of a portion of a modified flexible arm used in the described embodiment.

Throughout the drawings, identical or similar parts have the same reference numerals.

Syringe 10 includes an outer barrel 11 which is a solid cylindrical barrel without apertures except for openings at each end. An inner barrel 12 fits within the outer barrel 11 in such a manner as to slide longitudinally back and forth within the outer barrel 11 in meshing engagement. The inner barrel 12 has a narrow neck 13 at one end and is open at the opposite end 14. The neck 13 is adapted to receive a needle housing 15 including a needle 16. It will be apparent that the needle 16 is in fluid communication with a chamber 17 within the inner barrel 12. Once fitted to the neck 13, the needle housing 15 and needle 16 project from a first end 18 of the outer barrel 11.

A spring 20 is located in the first end 18 of the outer barrel 11 and acts on the inner barrel 12 to bias the inner barrel 12 towards the second end 19 of the outer barrel 11.

A piston 21 is located within the inner barrel 12 and is mounted on one end of a piston actuating rod 22. The piston actuating rod 22 enters the second end 19 of the outer barrel and the open end 14 of the inner barrel. The outer end of the piston rod 22 is provided with a limit catch 23, which will be described below. A flange 24 at the second end 19 of the outer barrel facilitates operation of the syringe. An end flange 34 facilitates operation of the plunger actuating rod 22.

The outer barrel has first and second annular grooves 25 and 26, respectively, on its inner surface. The purpose of the grooves 25 and 26 will become apparent below.

The above description presents the main components of the injector according to the embodiment of fig. 1-6 and the embodiment of fig. 7-11. In the first embodiment, the inner barrel 12 has a pair of diametrically opposed longitudinal slots 27 (see fig. 6) at the open end 14, the slots 27 forming a pair of opposed flexible arms 28. The flexible arm 28 has a lip 29 extending about its distal end which is adapted to engage one or the other of the annular grooves 25 and 26. The slot 27 allows the flexible arms 28 to move slightly towards each other to disengage the lip 29 from one or the other of the grooves 25 and 26. The structure of the inner barrel, and in particular the structure of the flexible arms 28, is more clearly shown in figure 6. The piston actuating rod 22 is provided with an annular skirt 30 having a tapered edge for engaging the corresponding arm 28 to remove the lip 29 from the corresponding grooves 25 and 26 (described below).

In the embodiment of fig. 7-11, the flexible arms 28 are much narrower in construction (see fig. 11) and essentially comprise a pair of opposed fingers extending from the open end 14 of the inner barrel 12. The flexible arms or fingers 28 in turn have lips 29 which engage one or the other of the annular grooves 25 and 26. In addition, the arm 28 has a latch 31 extending towards the second end 19 of the outer barrel 11. The actuating rod 22 is provided with an annular skirt 32 similar to the skirt 30 of the previous embodiment, but having an inwardly directed ridge 33 extending around the end of the skirt. Otherwise, the structure of the syringe in the embodiment of FIGS. 7-11 is the same as that of the previous embodiment.

As mentioned above, the outer end of the plunger actuating rod 22 includes a limit catch 23. Basically, the limit catch prevents the plunger actuating rod 22 and the plunger 21 from moving towards the front or needle end of the inner barrel 12 during the first operational phase of the syringe. Once the plunger actuating rod 22 is initially forced inwardly towards the needle end of the syringe, the limit catch changes its configuration whereby the plunger can move forwardly to the end most position of movement within the inner barrel on the next depression of the plunger actuating rod.

Specifically, upon initial depression of the piston rod 22, the fingers 36 of the limit catch 23 engage the end 19 of the outer barrel 11 and pivot from the position shown in FIG. 1 to the position shown in FIG. 2, thereby preventing further movement (depression) of the piston. This pivoting is facilitated by a flexible joint between the ends of the fingers. The fingers 36 are then locked in this pivoted position. The pivotal movement of the finger 36 severs a membrane 38 (see figure 2(a)) which initially holds the arms 37 of the limit catch 23 inwardly on the body of the piston rod 22. Thus, upon withdrawal of the piston rod 22 the arms 37 spring or spread outwardly to the position shown in fig. 3, wherein the tongue and groove 39 locks the arms 37 in the new position. The fingers cannot engage the end of the outer barrel 11 on the next depression of the lever 22, thus facilitating extended depression of the piston (to the end of the inner barrel 12).

The operation of the syringe is as follows. The syringe is packaged after manufacture in a sealed package without the needle housing 15 and needle 16 and under certain conditions the inner barrel and plunger are substantially in place as shown in figures 1 and 7 respectively. The user removes the syringe from the packaging and mounts the needle housing 15 with the attached needle 16 on the neck 13 of the inner barrel 12. The plunger actuating lever 22 is then depressed by applying thumb pressure on the end flange 34 whilst the outer barrel 11 is held between the first and second fingers until the actuating lever 22 is fully depressed into the inner barrel 12 and the limit catch 23 prevents further movement. In this position, the piston 21 almost reaches the neck 13 of the inner barrel and only a very small chamber exists in the inner barrel between the piston 21 and the neck 13. It should be noted at this point that movement of the inner barrel 12 relative to the outer barrel 11 is prevented by the lip 29 engaging the annular groove 25 of the outer barrel (see figures 1(a) and 7(a) respectively). Upon such initial actuation, the syringe is in the condition shown in figures 2 and 8, respectively. The purpose of the limit catch is to prevent the lip 29 from being released from the slot 25 on initial depression of the plunger actuating rod, which would prevent use of the syringe (as will be described below).

The next action is to aspirate the drug into the inner barrel 12 through the needle 16. The needle 16 is placed within the medicament and the piston is pulled outwardly to a position shown in figure 3. The inner barrel remains firmly fixed relative to the outer barrel.

The next action is to depress the plunger to inject the medicament, which moves all the way to the end of the inner barrel 12 when the plunger actuating rod 22 is actuated (as shown in figure 4). In other words, the limit catch 23 does not limit the internal movement of the actuating rod 22 at this second depression. In the case of the first embodiment, when the piston 21 reaches its innermost end, the projection 30 on the stem 22 engages the flexible arms 28 and (as shown in figure 4 (a)) the camming action causes the lip 29 on each arm 28 to ride out of the annular groove 25. In this regard, once pressure is released from the piston rod 22, the spring 20 forces the inner barrel toward the second end 19 of the outer barrel because there is nothing between the two barrels to impede their relative movement. Of course, this movement is dependent upon the user releasing pressure on the piston actuating rod 22.

The inner barrel continues to move relative to the outer barrel until the inner barrel assumes the position shown in figure 5 in which the lip 29 of each flexible arm 28 is located within the second annular groove 26. In this position, needle 16 is fully withdrawn into outer barrel 11.

As can be seen in fig. 5, the plunger actuating rod 22 can be depressed and cause the inner barrel to disengage the annular groove 26 whereby the needle can be moved out of the first end of the outer barrel. However, such action does not enable the syringe to be reused as it cannot lock the inner barrel or, more specifically, enter the annular groove 25. This is because spring 20 keeps inner barrel 12 against protrusion 30 or ridge 33, whereby lip 29 remains in a position to slide off of slot 25.

The slot 35 in the actuating rod 22 enables the portion of the actuating rod extending from the outer barrel to be broken off as a means of preventing further depression of the plunger, but even if this action is not performed, the syringe cannot be used anymore.

The operation of the syringe shown in the embodiment of fig. 7-11 is very similar in that: to eject the medicament from the chamber of the inner barrel 12, depression of the actuation rod 22 causes the ridge 33 of the annular skirt 32 to engage the latch 31 to slide the lip 29 out of the first annular groove 25 again (see figure 8 (a)). The spring 20 again causes the inner barrel to move towards the second end 19 of the outer barrel whereby the lip 29 engages in the second annular groove 26 of the outer barrel 11 (shown more clearly in figures 10 and 10 (a)). Fig. 9 and 9(a) show the position of the inner barrel transitioning between the two positions.

As can be seen in fig. 10 and 10(a), once the inner barrel is locked in the second annular groove 26, it cannot be moved by depressing the plunger actuating rod 22 because the engagement between the annular skirt 32 (or specifically the ridge 33 thereon) and the latch 31 is such that depression of the rod 22 cannot slide the latch 31 out of the groove. Thus, further actuation of the plunger or further movement of the inner barrel relative to the outer barrel is prevented and the needle is safely withdrawn into the outer barrel 11. A notch 35 in the actuating lever 22 enables a portion of the actuating lever to be broken off by protruding from the outer barrel, but such action is not necessary.

In a variation of the above embodiment, some of the flexible arms 28 on the inner barrel are different from those described above. The cross-sectional shape of the modified flexible arm 28 is shown in fig. 14. Along with some arms having modified profiles, the total number of arms 28 on inner barrel 12 increases, and preferably includes a total of at least four such arms, including at least two modified arms. The modified arm 28 is shorter than the other arms having the same profile as the arms shown in fig. 1-6, but is like the thin fingers in the embodiment of fig. 7-11. In the case of a total of four arms, they are evenly spaced around the inner barrel 12 with the two long arms diametrically opposed and the two short arms likewise.

The long arm is initially locked in the annular groove 25 and is released from the groove in the manner described above when the piston is fully depressed for the first time. It should be appreciated that the shorter arm 28 is not engaged by the lug 30 or skirt 32 as the case may be. This engagement is made with the longer arm. When the piston withdraws the shorter arm 28, which is not located in the slot 25, it must move through the slot 25 towards the second end 19. This is achieved by the sloping surface 39 projecting over the edge of the slot 25 closest to the second end 19. In other words, when the plunger is withdrawn under the bias of the spring 20, the shorter arms 28 deform inwardly towards the longitudinal axis of the syringe and they slide over the slots 25.

At the second end 19, the longer arms 28 are held away from the slots 26 because they engage the piston nose 30 or skirt 32 under the bias of the spring 20. The shorter arms are not under this influence and can spring outwardly into engagement with the slots 26 when the inner barrel reaches its furthest position towards the second end. Once engaged in the groove 26, the right angle lip 40 of the shorter arm is firmly seated in the groove 26 and, therefore, the inner barrel is prevented from moving all the way within the outer barrel towards the first end 18. Thus, the needle is permanently withdrawn into the outer barrel and the syringe cannot be used again.

It will be apparent that by the combination of the novel latching arrangement between the inner and outer barrels and the limit catch 23, a safe syringe is provided which is particularly reliable, relatively inexpensive to manufacture and does not require any physical action from the user in order to ensure that the syringe is not effective and cannot be reused.

It will be apparent that many changes can be made to the embodiments described above without departing from the spirit and scope of the invention. Those skilled in the art will readily envision a variety of mechanisms for latching and unlatching the inner barrel to prevent movement of the inner barrel relative to the outer barrel. Various piston configurations are also contemplated for disengaging the latch mechanism.

Claims

(modification according to article 19 of the treaty)

Statement of modification according to PCT clause 19(1)

1. The claims on pages 10, 11 and 12 of the original document are now removed and replaced with new claims on pages 10, 11 and 12.

1. A syringe, comprising: an outer barrel having first and second ends; an inner barrel longitudinally slidable within said outer barrel and adapted to support at one end a needle projecting through an aperture in said first end of said outer barrel, said needle being in fluid communication with a fluid-containing chamber of said inner barrel; and, a piston within said chamber actuable to draw fluid into said chamber and to inject fluid from said chamber through said needle, said piston being connected to an actuating rod extending from the other end of said inner barrel and from the second end of said outer barrel, said outer barrel having first and second spaced retaining means on its inner wall surface and said inner barrel having latching means for engaging said first or second retaining means and locking said inner barrel in one of two positions relative to said outer barrel: a first said position when said needle projects from said outer barrel and is in a use position; and, a second said position in which said needle is fully retracted within said outer barrel, biasing means for biasing said inner barrel towards said second position, said plunger actuating lever having means, means for contacting said latch means when said plunger is fully depressed to disengage said latch means from said first retaining position, whereby said needle is moved to said second position, wherein the latch means engages the second retaining means and cannot be re-engaged within the first retaining means, wherein a limit catch is provided on the actuating lever, the limit catch preventing the plunger from being fully depressed and disengaging the latch from the first slot upon initial actuation of the plunger, but allows the plunger to be depressed sufficiently to disengage the latch means for the next plunger depression.

2. The syringe of claim 1 wherein said retaining means comprises first and second slots, respectively.

3. The syringe of claim 2 wherein said needle is mounted on a needle support neck connected to said one end of said inner barrel.

4. The syringe of claim 3 wherein the groove is an annular groove on the inner wall surface.

5. The syringe of claim 4 wherein said latch means is permanently engaged within said second slot when said needle is moved to said second position.

6. A syringe as claimed in claim 5, wherein the means for contacting the latch means when the plunger is fully depressed comprises an annular skirt depending from the plunger actuating stem, the edge of the skirt being adapted to contact the latch means and disengage the latch means from the first slot.

7. The syringe of claim 6 wherein said latch means comprises a plurality of flexible arms extending longitudinally from the other end of said inner barrel toward said second end, said arms comprising one or more long arms and one or more short arms, said long arms or arms having a protrusion for engaging said first slot, to prevent movement of the inner barrel to the second position, the short arm or arm having a projection configured to move over the first slot, but not engage therein and become permanently engaged therein in the second groove, and when the piston is fully depressed to remove the projection from the first groove, the elongate arm or arms with means for engaging the annular skirt whereby the inner barrel is urged to move to the second position by the biasing means.

8. The syringe of claim 7 wherein there are two diametrically opposed said long arms and two diametrically opposed said short arms equally spaced about said inner barrel.

9. The syringe of claim 8 wherein said skirt has an inwardly directed annular ridge at its edge for engaging said arm to remove said projection from said first slot when said plunger is fully depressed.

10. The syringe of claim 9 wherein said biasing means is a compression spring located between said outer and inner barrels and carried on said first end of said outer barrel and on a flange on the outer surface of said inner barrel.

11. A syringe as claimed in any one of the preceding claims, wherein said limit catch comprises corresponding hinged fingers mounted on opposite sides of said piston actuating stem at the outer ends thereof, each finger initially extending parallel to the longitudinal axis of said stem in a linear configuration and being connected to said stem at each end of the finger, the fingers being configured such that: initial actuation of the lever causes the end of each finger towards the outer barrel to bear on the end of the outer barrel, causing the connection between the inner ends of the fingers and the lever to break, and bending the fingers into a generally right angle configuration to prevent further inward movement of the piston, the fingers being locked in the right angle configuration and pivoted away from the lever by virtue of the bias in the connection between the fingers and the outer end of the lever when the lever is withdrawn, whereby the fingers do not engage the end of the outer barrel when the piston actuating lever is subsequently actuated, so that the lever is prevented from being fully depressed.

Claims (12)

1. A syringe, comprising: an outer barrel having first and second ends; an inner barrel longitudinally slidable within said outer barrel and adapted to support at one end a needle projecting through an aperture in said first end of said outer barrel, said needle being in fluid communication with a fluid-containing chamber of said inner barrel; and, a piston within said chamber actuatable to draw fluid into said chamber and to inject fluid from said chamber through said needle; said piston being connected to an actuating rod extending from the other end of said inner barrel and the second end of said outer barrel; said outer barrel having first and second spaced retaining means on an inner wall surface thereof and said inner barrel having latching means for engaging said first or second retaining means and locking said inner barrel in one of two positions relative to said outer barrel: a first said position when said needle projects from said outer barrel and is in a use position; and, a second said position wherein said needle is fully retracted within said outer barrel; biasing means for biasing said inner barrel towards said second position; the plunger actuating lever has means for contacting the latch means when the plunger is fully depressed to disengage the latch means from the first retaining position, whereby the needle moves to the second position wherein the latch means engages the second retaining means and cannot be re-engaged within the first retaining means.

2. The syringe of claim 1 wherein said retaining means comprises first and second slots, respectively.

3. The syringe of claim 2 wherein said needle is mounted on a needle support neck connected to said one end of said inner barrel.

4. The syringe of claim 3 wherein a limit catch is provided on the actuation lever, the limit catch preventing the plunger from being fully depressed and preventing the latch from disengaging from the first slot upon initial actuation of the plunger, but allowing the plunger to be depressed sufficiently to disengage the latch on the next plunger depression.

5. The syringe of claim 4 wherein the groove is an annular groove on the inner wall surface.

6. The syringe of claim 5 wherein said latch means is permanently engaged within said second slot when said needle is moved to said second position.

7. The syringe of claim 6 wherein the means for contacting said latch means when said plunger is fully depressed comprises an annular skirt depending from the plunger actuating stem, the edge of said skirt being adapted to contact said latch means and disengage said latch means from said first slot.

8. The syringe of claim 7 wherein said latch means comprises a plurality of flexible arms extending longitudinally from the other end of said inner barrel toward said second end, the arms comprising one or more long arms and one or more short arms, the long arms or arms having a protrusion engaging the first slot, to prevent movement of the inner barrel to the second position, the short arm or arm having a projection configured to move over the first slot, but not engage therein and become permanently engaged therein in the second groove, and when the piston is fully depressed to remove the projection from the first groove, the long arm or arm with a latch means is adapted to engage the annular skirt whereby the inner barrel is forced to move to the second position by the biasing means.

9. The syringe of claim 8 wherein there are two diametrically opposed said long arms and two diametrically opposed said short arms equally spaced about said inner barrel.

10. The syringe of claim 9 wherein said skirt has an inwardly directed annular ridge at its edge for engaging said arm to remove said projection from said first slot when said plunger is fully depressed.

11. The syringe of claim 10 wherein said biasing means is a compression spring located between said outer and inner barrels and carried on said first end of said outer barrel and on a flange on the outer surface of said inner barrel.

12. The syringe of any of claims 4 to 11 wherein said limit catch comprises corresponding hinged fingers mounted on opposite sides of said piston actuating stem at the outer ends thereof, each finger initially extending in a linear configuration parallel to said stem longitudinal axis and connected to said stem at each end thereof in such a configuration that the fingers are: initial actuation of the lever causes the end of each finger towards the outer barrel to bear on the end of the outer barrel, causing the connection between the inner ends of the fingers and the lever to break, and bending the fingers into a generally right angle configuration to prevent further inward movement of the piston, the fingers being locked in the right angle configuration and when the lever is withdrawn, the fingers being pivoted away from the lever by virtue of the bias in the connection between the fingers and the outer end of the lever, whereby the fingers do not engage the end of the outer barrel when the piston actuating lever is subsequently actuated, so that the lever is prevented from being fully depressed.