AU2001243948A1 - A retractable syringe system - Google Patents

Description

A RETRACTABLE SYRINGE SYSTEM

This invention relates to a safety syringe system of the retractable needle type particularly adapted for assisting in preventing needle stick injuries.

Needle stick injuries occur when hypodermic needles accidentally pierce the skin either during use, after use or after they are carelessly discarded.

This invention is particularly directed to what in effect is a retracting needle type system for preventing needle stick injuries.

United States Patent No. 5492536 describes a device that has an inner syringe body and an outer sheath slideable along the inner syringe body. A latching arrangement is fixed between the inner and outer sheaths at the end opposite to the needle and a spring urges the sheath to a protecting position when the latch is released.

United States Patent No. 6004296 again describes a device that has inner and outer sheathes but the outer sheath is formed of two components telescoping over each other. There is no spring between the moving parts so that a manual operation is needed to make the needle safe.

United States Patent No. 60173219 is similar to the one described immediately above and having a two component outer sheath. This device is described as being able to be applied to an existing syringe. Once again there is no spring action and no locking in the retracted position. Once moved forward, however, the sheath can be locked in position.

United States Patent No. 5562626 uses a spring arranged between a syringe barrel and an outer sliding sheath. There is a locking arrangement in the retracted position that is released by the forward movement of the syringe plunger when the plunger thumb flange strikes a release mechanism.

United States Patent No.4702732 shows a track arrangement between an inner and outer sheath which guides the outer sheath in its longitudinal movement and provides a stop at the end to retain the sheath over the needle in the forward position. It is the object of this invention to provide a device which has significant advantage over the devices discussed above particularly in relation to the ease of manufacture and ease of operation or at least to provide a device which provides the public with a useful alternative.

In one form therefore, although this may not necessarily be the only or broadest form the invention is said to reside in a safety syringe including a syringe tube having a plunger slideable therein, the syringe tube having a needle boss and a needle at the end thereof and a flange at the other end thereof, a tubular sheath over the syringe tube and slideable there along, the tubular sheath having a flange at one end thereof and an aperture of restricted diameter at the other end, the aperture being sized to frictionally engage the needle boss with a needle extending therethrough, and resilient means acting between the syringe tube and the tubular sheath whereby in a first position with the resilient means in a relaxed position the tubular sheath overlies the needle and in a second position with the resilient means in a compressed position the needle extends through the aperture and the needle boss frictionally engages the aperture to retain the tubular sheath in a position in which the needle is exposed.

It will be seen that by this invention there is provided an arrangement by which the tubular sheath is held back against the resilient means by the frictional engagement of the needle boss on the aperture in the tubular sheath and hence no specific catching or latching arrangement is necessary. A small force can be used to overcome the frictional engagement to enable the resilient means to withdraw the needle into the tubular sheath. Hence, the safety syringe according to this invention is inherently safe because a simple force such as a light finger force or even the action of dropping the syringe so that it strikes a surface is sufficient to overcome the frictional engagement to release the tubular sheath that it will cover the needle.

In a preferred form of the invention the tubular sheath is transparent so that the graduations on the syringe tube can be read through the tubular sheath.

In one form of the invention the syringe tube and needle boss may be integral and in an alternative form the needle boss and needle may be removable from the syringe tube.

In one preferred form of the invention the resilient means may be a helical coil spring which either acts between a flange on the syringe tube and the flange on the tubular sheath or it may be positioned within the tubular sheath and act between the syringe tube and the tubular sheath.

There may be further provided a cap for the needle. Such a cap may be designed to be used when the needle is in the retracted position within the tubular sheath and may include a tubular portion to overly the needle and a head portion which engages frictionally inside the aperture in the tubular sheath to retain the cap in that position.

There may also be provided an arrangement within the tubular sheath by which the needle is prevented from being exposed after it has been used and then withdrawn into the tubular sheath by the action in fact of the tubular sheath moving forward.

This may be done by the use of a flap within the tubular sheath which is held back by the needle cap when the device is supplied but after the needle and needle boss are pushed through the aperture and the needle cap disengaged the flap is free to move in front of the needle as it is retracted and then prevent the needle from being moved forward again.

The flap may have a resilient bias acting upon it so that it tends to assume a position in which it covers the aperture in the end of the tubular sheath and can be held back against the inner wall of the tubular sheath against the resilient bias.

The flap may be integrally molded with the tubular sheath or it may be inserted into or onto the tubular sheath during assembly.

One advantage of this invention is that it may be used with an existing hypodermic syringe. The assembly of syringe tube, plunger needle boss and needle is unchanged, at least in some embodiments, than those used at present.

In an alternative form, therefore, the invention is said to reside in a tubular sheath adapted to be placed over a syringe tube and to be slideable therealong, the tubular sheath having a flange at one end thereof and an aperture of restricted diameter at the other end, the aperture being sized to frictionally engage the needle boss with a needle extending therethrough when the tubular sheath is positioned onto the syringe tube, and resilient means acting between the syringe tube and the tubular sheath therethrough when the tubular sheath is positioned onto the syringe tube.

In a further form of the invention there is provided a safety syringe comprising a syringe tube, a plunger slideable in the syringe tube, a flange at one end of the syringe tube and a needle and needle boss at the other end of the syringe tube, a sheath slideably positioned over the syringe tube, said sheath having an aperture at one end to frictionally engage the needle boss and be retained in position in a retracted position on the tube, resilient means biasing the sheath to the extended position, a cap attached to the syringe flange to extend partially over the sheath, stop means on the sheath and cap to limit the extended movement of the sheath, and trigger means acting on aperture to permit the sheath to extend.

In a still further form of the invention there is provided a safety syringe comprising a syringe tube, a plunger slideable in the syringe tube, a flange at one end of the syringe tube and a needle and needle boss at the other end of the syringe tube, a sheath slideably positioned over the syringe tube, said sheath having an aperture at one end through which the needle can extend, resilient means biasing the sheath to the extended position, a cap attached to the syringe flange to extend partially over the sheath, interengaging means on the sheath and the cap to retain the sheath in the retracted position, stop means on the sheath and cap to limit the extended movement of the sheath, and trigger means acting on the sheath to disengage the interengaging means on completion of the inward stroke of the plunger to permit the sheath to extend under the influence of the resilient means.

This then generally describes the invention but to assist with understanding reference will now be made to the accompanying drawings that show preferred embodiments of the invention.

In the drawings:

Figure 1 shows a partially cut away view of a first embodiment of safety syringe according to this invention,

Figure 2 shows a longitudinal sectional view of the embodiment shown in Figure 1 with the syringe in the extended position, Figure 3 shows a longitudinal sectional view of the embodiment shown in Figure 1 with the syringe in the retracted position,

Figure 4 shows a perspective view of an alternative embodiment of a safety syringe according to this invention,

Figure 5 shows a longitudinal cross sectional view of the embodiment shown in Figure 4 with the needle in the extended position,

Figure 6 shows a longitudinal sectional view of the embodiment shown in Figure 4 with the needle in the retracted position,

Figure 7 shows a detail of the embodiment shown in Figure 5,

Figure 8 shows detail of an embodiment shown in Figure 2,

Figure 9 shows a helical spring suitable for the embodiment shown in Figure 7,

Figure 10 shows a helical spring suitable for the embodiment shown in Figures 1 , 2 and 3,

Figure 11 shows detail of an embodiment of a flap arrangement particularly useful with the embodiment shown in Figures 1 , 2 and 3,

Figure 12 shows a further stage in the use of the flap of the embodiment shown in Figure 11 ,

Figure 13 shows a still further stage in the use of the flap of the embodiment shown in Figure 11 ,

Figure 14 shows detail of an embodiment of an alternative flap arrangement particularly useful to make the device of the present invention safer to use,

Figure 15 shows a further stage in the use of the flap of the embodiment shown in Figure 14, Figure 16 shows a final stage in the use of the flap of the embodiment shown in Figure 14.

Figure 17 (a), (b) and (c) show a further form of the invention,

Figure 18 (a), (b) and (c) show a still further form of the invention, and

Figure 19 (a), (b), (c), (d), and (e) illustrate a still further form of the invention.

Now looking more closely at the drawings and in particular the embodiment shown in Figures 1 , 2 and 3 it will be seen that the safety syringe according to this invention comprises an outer sheath 1 into which slidably fits a hypodermic syringe generally shown as 2. The hypodermic syringe includes a syringe tube 3 and a plunger 4. The syringe tube has a flange 5 at the end opposite the needle 6 and needle boss 7. The outer tube has a flange 8 at one end and an aperture 9 at the other end. A cap 10 fits into the aperture 9 to cover the needle as can particularly be seen in Figure 3 and removed in Figure 2. A helical spring 11 is clipped at one end 12 over the flange 8 and at the other end 13 over the flange 5. The helical spring 11 is of a type, which is normally in the extended shape as shown in Figure 3 but when compressed goes into the state shown in Figure 2.

As supplied the safety syringe appears as shown in Figure 3. When it is desired to be used the flange 5 is moved towards the flange 8 against the helical spring 11. This causes the cap 10 to be ejected and the needle 6 to extend out through the aperture 9 until the boss 7 engages with the aperture to frictionally hold the spring 11 in the compressed condition. The syringe plunger 4 can then be used in the normal manner to draw up a liquid to be injected or to withdraw blood or for whatever other medical purpose.

After being used a slight force separating the flanges 5 and 8 is sufficient to disengage the frictional engagement between the boss 7 and the aperture 9 so that the syringe returns to the position shown in Figure 3 with the assistance of the helical spring 11. If required the cap 10 can then be replaced.

In the embodiment shown in Figures 4, 5 and 6 the construction is substantially the same as shown in Figures 1 , 2 and 3 except that the helical spring 15 is in the bottom of the tubular sheath 1 and engages into a recess 16 in the bottom of the tubular sheath 1 as can be seen particularly in Figure 7. The other end of the helical spring 15 engages in a recess at the base of the boss 7 of the syringe tube 3. When the needle is in the retracted position as shown in Figure 6 the spring 15 is in a relaxed state but when the syringe has been pushed forward such that the boss 7 engages in a frictional manner with the aperture 9 the spring 15 is compressed. A slight movement of the flanges 5 and 8 apart will disengage the frictional engagement of the boss 7 with the aperture 9 so that the helical spring 15 acts to retract the needle into the tubular sheath. Once again the cap 10 can be replaced as shown in Figure 6.

Figure 8 shows in detail how the boss 7 in the embodiment shown in Figures 1 to 3 frictionally engages with the aperture 9 at the end of the tubular sheath 1.

Figure 10 shows the helical spring 11 suitable for the embodiment shown in Figures 1 to 3 with the hooked ends 12 and 13 which engage over the flanges 8 and 5 respectively.

In an alternative arrangement apertures may be provided in the flanges 5 and 8 and the ends of the spring may be pushed through these apertures and crimped over.

Figures 11 , 12 and 13 show details of an embodiment of a flap arrangement particularly useful with the embodiment shown in Figures 1 , 2 and 3. Within the tubular sheath 1 is a flap 20 which in one position is held back against the inner wall of the tubular sheath by the syringe tube 3 as shown in Figure 11 or by the cap 10 and needle boss 7 as shown in Figure 12. The flap is held back against a resilient bias which is tending to move the flap so that it extends over the aperture in the end of the tubular sheath. By this arrangement the flap is held back by until such time that the tubular sheath is moved forward over the exposed needle. The flap is acted upon by the resilient bias and then moves to assume the position as shown in Figure 13 in which position it will prevent or retard movement of the needle forward again. Depending on the constructional material of the flap it may bend the needle if the needle is forced against it or the needle may pierce it.

Hence the syringe assembly is made of a single use type because attempted second use will cause damage to the needle. Figures 14 to 16 show details of an embodiment of an alternative flap arrangement by which the syringe system of the present invention may be made safer by the use.

In this embodiment there is an integral flap 30 formed out of the body of the tubular sheathl with a foot 31 extending into the interior of the tubular sheath. An integral hinge 32 connects the flap 30 with the tubular sheath 1. As supplied, however, the integral flap is deflected sideways by the foot 31 engaging with the side of the cap 10 when it is inserted through the aperture 9. The integral flap 30 is, however, resiliently biased by the construction of the integral hinge 32 to a position in which the foot 31 lies within the tubular sheath in a needle engaging position as will be described in relation to Figure 16.

Figure 15 shows a further stage in the use of the flap of the embodiment shown in Figure 14. In this view the syringe tube 3 has been pushed in against the load of the spring 11 until the cap 3 has been freed and the foot 31 has ridden up onto the syringe needle boss 7. With the syringe cap 10 removed and the boss 7 holding back the foot 31 the syringe can be used in the normal manner.

Figure 16 shows a final stage in the use of the embodiment shown in Figure 14. After the syringe has been used frictional engagement of the boss 7 in the aperture 9 is released and the syringe tube 3 is moved back or the tubular sheath 1 is moved forward so that the needle 6 retracts inside the sheath 1. At this stage the foot 31 moves in front of the needle so that the needle cannot be moved forward again.

Although this flap 30 has been described in this embodiment as integral with the tubular sheath it may in alternative embodiments be an additional component mounted or fastened to the tubular sheath to carry out the same function.

The tubular sheath may be constructed from any suitable material and is preferably transparent. It may be formed of plastics material by injection molding.

The above examples of the invention are very satisfactory. However the safety procedure requires that there be a physical movement between the flange on the syringe and the flange on the sheath. In the flowing embodiments the sheath is automatically extended on the completion of the inward movement of the plunger in the barrel of the syringe. Referring to Figure 17 (a), (b) and (c) the sheath has the aperture 9 to frictionally engage the needle boss 7, the spring 11 positioned between the end of the barrel and the end of the sheath. However the sheath does not have a flange at its upper end. To the upper end of the syringe there is attached a cap 40 to extend over the upper end of the sheath 1 , the sheath at its upper end having an outwardly extending circumfrential shoulder 4, the cap having an inwardly directed shoulder at its outer end, the shoulders 41 and 42 effectively limiting movement of the sheath in its extended position. A pair of diametrical holes 49 is formed through the flange 5 of the syringe to receive the pair of legs 43 of a trigger 44, the legs extending from a ring 45 of the trigger. The legs are so dimensioned that at the completion of the inward movement of the plunger the plunger end engages the trigger forcing the legs inward to engage the end of the sheath sufficient to release the frictional grip of the aperture 9 on the base of the syringe, the spring thus extending the sheath to cover the needle.

To prevent reuse of the syringe it is preferred the legs have a serrated or sawtooth edge 46 to prevent withdrawal of the legs.

While the frictional grip of the aperture 9 on the boss 7 is sufficient to hold the sheath against the force of the compressed spring 11 , this may be supplemented by the shoulder 41 on the sheath engaging small notches or grooves on the inside of the cap 40. Figure 18 shows an embodiment similar to that of Figure 17 except that the spring 11 is positioned between the end of the sheath and a ring 48 engaged by the ends of the legs 43.

It is noted that according to the invention the safety device is attachable to a conventional syringe. To attach the syringe the pair of holes 49 are drilled through the end flange 5, and the cap 40 and assembled sheath 1 are attached over the syringe by fixing the cap 40 to the flange 5 by any suitable adhesive. In this position the sheath is in its retracted position and the needle boss 7 frictionally engages the aperture 9 in the end of the sheath 1. The legs 43 of the trigger are then inserted through the holes 49.

Figures 19 (a) to (e) are directed to a further form of the invention in which similar features have the same reference numerals as in previous embodiments. In this embodiment the sheath 1has beyond the flange 8 a tubular extension 50. A ring

51 is positioned on the tubular extension 50 adjacent the flange 8, and a further ring

52 is positioned at the end of the tubular extension 50. As shown when assembled the shoulder 42 engages over the ring 51. On completion of the movement of the plunger the trigger 4 engages the end of the tubular extension 5 with sufficient force to release the frictional grip on the boss 7 and also to disengage the shoulder from the ring 51 thus permitting the spring to extend the sheath to cover the needle. The ring 52 is thus engaged by the jaws 42 to prevent the sheath from further movement.

In this embodiment the spring is positioned at the end of the syringe, however it is to be realised the spring can be positioned between the tubular extension 50 and the trigger legs 43.

Thus it can be seen that by the invention a standard syringe can easily be adapted to be a safety syringe. In the preferred embodiment the flange of the syringe has two holes drilled there through and the mechanism adhered to the flange. Thus a special syringe does not have to be produced to be a safety syringe.

Throughout this specification various indications have been given as to the scope of the invention but the invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration only and not for, limitation.

In this specification the words 'comprise' and 'include' and variations such as 'comprising' and 'including' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims (16)

1 A safety syringe including a syringe tube, a plunger slideable therein, a needle boss and needle at one end to the syringe tube and flange at the other end thereof, a tubular sheath adapted to slide over the syringe tube, an aperture of restricted diameter at one end of the sheath, the aperture being sized to frictionally engage the needle boss with the needle extending therethrough, resilient means acting between syringe tube and the tubular sheath, the arrangement being such that with spring in the compressed condition the sheath is frictionally held in the position to expose the needle but when the frictional hold is released the spring extends the sheath to cover the needle.

2 A safety syringe as defined in claim 1 and including means to retain the sheath on the syringe tube in the extended position.

3 A safety syringe as defined in claim 1 in which the sheath has a flange at the end opposite the aperture, whereby a small force on the sheath flange will release the frictional grip.

4 A safety syringe as defined in claim 3 wherein the resilient means is a spring acting between the syringe flange and the sheath flange and attached to both flanges whereby the sheath is retained in position in the extended position.

5 A safety syringe as defined in any one of the preceding claims and including a cap to cover and protect the needle with the sheath in the retracted position, said cap also being inserted in the aperture of the sheath when in the extended position.

6 A safety syringe as defined in claim 1 including means to prevent reuse of the syringe, said means including a flap within the tubular sheath which is retained in a non-active position by the syringe but when the sheath is moved to its extended position the flap extends to cover the aperture in the sheath.

7 A safety syringe comprising a syringe tube, a plunger slideable in the syringe tube, a flange at one end of the syringe tube and a needle and needle boss at the other end of the syringe tube, a sheath slideably positioned over the syringe tube, said sheath having an aperture at one end to frictionally engage the needle boss and be retained in position in a retracted position on the tube, resilient means biasing the sheath to the extended position, a cap attached to the syringe flange to extend partially over the sheath, stop means on the sheath and cap to limit the extended movement of the sheath, and trigger means acting on aperture to permit the sheath to extend.

8 A safety syringe as defined in claim 7 wherein the trigger means includes completion of the plunger stroke to overcome the frictional engagement of the boss on a pair of arms to engage the end of the sheath.

9 A safety syringe as defined in claim 8 wherein the pair of arms extend through apertures in the syringe flange, the arms being connected to the trigger boss to be engaged by the plunger at the completion of the inward stroke of the plunger.

10 A safety syringe as defined in claim 7 wherein the stop means on the sheath and cap comprise an inward shoulder on the end of the cap and an outward shoulder on the end of the sheath.

1 1 A safety syringe as defined in any one of claims 8 to10, and including means to prevent outward movement of the arms after the sheath has been extended to thus prevent reuse of the syringe.

12 A safety syringe as defined in claim 11 where means to prevent outward movement of the arms are provided by sawteeth on the arms permitting inward movement but preventing outward movement.

13 A safety syringe as defined in any one of claims 7 to12 wherein the outward shoulder on the sheath can engage a recess or recess on the inside of the cap to assist the frictional grip of the boss on the aperture.

14. A safety syringe as defined in any one of claims 7 to 13 wherein the resilient means is a spring between the end of the tube and the end of the sheath.

15. A safety syringe as defined in any one of claims 7 to13 wherein the resilient means is a spring between the inner end of the sheath and the trigger arms.

16. A safety syringe as defined in claim 10 wherein the sheath has a tubular extension extending under the cap. said extension having a circular ring engaged by the intumed shoulder of the sheath to assist in the frictional grip of boss on the aperture.

17 A safety syringe comprising a syringe tube, a plunger slideable in the syringe tube, a flange at one end of the syringe tube and a needle and needle boss at the other end of the syringe tube, a sheath slideably positioned over the syringe tube, said sheath having an aperture at one end through which the needle can extend, resilient means biasing the sheath to the extended position, a cap attached to the syringe flange to extend partially over the sheath, interengaging means on the sheath and the cap to retain the sheath in the retracted position, stop means on the sheath and cap to limit the extended movement of the sheath, and trigger means acting on the sheath to disengage the interengaging means on completion of the inward stroke of the plunger to permit the sheath to extend under the influence of the resilient means.