CN106668989B

CN106668989B - Retractable syringe

Info

Publication number: CN106668989B
Application number: CN201510761492.0A
Authority: CN
Inventors: 艾伦·沃尔什
Original assignee: C La China Pty Ltd
Current assignee: C La China Pty Ltd
Priority date: 2015-11-10
Filing date: 2015-11-10
Publication date: 2021-11-09
Anticipated expiration: 2035-11-10
Also published as: CN106668989A

Abstract

An auto-retractable syringe having a barrel and a plunger, wherein the plunger is coupled with an otherwise fixed needle hub such that a biasing element can urge the needle hub into a cavity in the plunger.

Description

Retractable syringe

Technical Field

The present invention relates to the field of hypodermic syringe manufacture. In particular, the present invention relates to a retractable safety syringe in which the needle can be retracted into the syringe barrel after use by a spring or similar mechanism.

Background

Safety syringes for hypodermic needles are becoming a very important health care tool. The ability of the syringe to prevent needle sticks is extremely important in preventing the spread of blood borne diseases.

One particular type of safety syringe is a retractable syringe. I.e. a syringe which is internally provided with a mechanical device, usually a spring, which is activated after the fluid injection is completed, whereby the spring works to retract the needle inside the syringe barrel. This prevents needle stick injuries caused by the needle and, in particular, enables the needle operator to withdraw the needle tip in a single-handed operation, thereby making it easier to administer injections to patients in busy hospitals or clinics.

WO2006/096901 discloses a retractable syringe in which there is provided a syringe having a hollow plunger capable of receiving a retractable needle and needle hub, the needle hub and needle being actuated into the plunger by expansion of a spring which is released by pressure exerted by the plunger on an assembly which holds the needle hub in place by a restraining spring release.

Such syringes are commonly referred to as "auto-retractable", meaning that needle retraction is initiated by the mechanism of the syringe itself, rather than requiring the operator to pull, push or otherwise move the needle into the syringe barrel.

A disadvantage of such retractable syringes is that they are prone to fluid leakage and the mechanism is susceptible to operational reliability problems.

Syringes of other designs are difficult or expensive to manufacture due to their relative complexity. Still other designs of syringes do not allow for full dispensing of the injectable fluid due to the dead space left in the syringe barrel. It is therefore an object of the present invention to provide a retractable syringe arrangement which ameliorates at least some of the problems associated with the prior art.

Disclosure of Invention

According to a first aspect of the present invention there is provided an auto-retractable syringe having a barrel and a plunger movable within the barrel, the barrel having a gland assembly disposed within a front portion thereof, the gland assembly housing a movable needle hub to which a hypodermic needle is connected; wherein a biasing element is disposed between the gland assembly and the needle hub to facilitate pushing the needle hub into the tubing; wherein the plunger has a lumen capable of receiving the needle hub; wherein the needle hub is held in place by a retaining means prior to use, preventing ingress and egress of the needle hub into the barrel; wherein the plunger, in combination with the needle hub, causes the detent to release, enabling the biasing element to push the needle hub into the lumen of the plunger.

Such syringes represent an improvement over the prior art in that leakage of fluid is reduced or eliminated, and further the syringe is simplified and thus of more economical construction. The instant the needle is within the barrel by means of the biasing element (e.g. spring) means that the syringe can be used and discarded in one action and can be operated by one hand.

Preferably, the retaining means comprises one or more retaining regions in the needle hub, the one or more retaining regions being profiled so as to prevent movement of the needle hub into and out of the barrel when engaged; and a set of resilient fingers having a profile complementary to one or more stops occupying a stop region, thereby locking the needle hub in place against the urging force of the biasing element. More preferably, the inner contour of the stopper is square or rectangular. This stop arrangement, which more securely holds the needle hub in place by inhibiting it from moving in both directions, provides a unique advantage.

In a preferred embodiment, the upper region of the resilient claw has an inclined face that is inclined away from the needle hub, such that when engaged by an element that moves in the injection direction, the applied force can thereby help to push the resilient claw away from the needle hub, thereby releasing the needle hub and enabling the biasing element to push the needle hub into the plunger. This upper surface makes the engagement of the elastic claw more reliable and can be simplified by another moving member to disengage the elastic claw in a controlled state.

Preferably, the plunger has a stop at its fluid coupling end, the stop being held in place by a stop means, which can be overcome by the force of a biasing element pushing the needle hub into the plunger. This allows the plunger to be pushed back into the cavity with the needle. It also makes plunger manufacturing easy and provides plunger stops having a more efficient shape, such as stops having a partially spherical fluid-engaging surface.

In a preferred embodiment, the biasing element is a spring and the spring is mounted in a partially compressed manner. Partial compression of the spring (as opposed to full compression) may make the construction simpler and better control the retraction operation.

Preferred embodiments of the invention will now be described by way of specific, non-limiting examples with reference to the accompanying drawings.

Drawings

Figure 1 is a schematic cross-sectional view of the "needle" end of a syringe according to the present invention.

Figure 2 is a schematic cross-sectional view of an injector according to the present invention prior to completion of an injection.

Fig. 3 is a schematic cross-sectional view of the syringe of fig. 2 about to complete an injection.

Fig. 4 is a schematic cross-sectional view of the syringe of fig. 3 showing subsequent retraction of the needle hub.

Detailed Description

The invention may be embodied by disposing the working member at the "dispensing" end of a retractable hypodermic syringe. The invention can be better understood with reference to the following drawings.

Referring to fig. 1, an auto retractable syringe 5 is shown. The main components of the syringe are the barrel 10, plunger 15, gland 20 and needle 25. The gland 20 is inserted into the barrel 10 in a press fit manner to receive the needle hub assembly therein. The gland can also adopt a screw-in type.

The needle hub assembly includes a needle hub 30 into which the needle 25 is inserted. A slide activated sleeve 35 is mounted around the needle hub and a partial compression spring 40 is provided between these two components. Spring 40 contacts stepped rearward facing surface 45 of the needle hub and inwardly stepped surface 50 of sleeve 35. The spring thus acts to tend to urge the needle hub 30 rearwardly relative to the hub 35.

However, this tendency of the spring 40 is impeded by the stop means prior to dispensing. This means consists of three resilient fingers 55 projecting from the inner front surface 60 of the gland 20. Each of the jaws has a square or rectangular flange 65 facing the needle hub 25. The resilient fingers also have a rearward "head" surface 85 that is smooth but sloped so that its uppermost tip is furthest from the surface of the hub 30 and said surface is closer to the hub 30 or gland 20 at the "dispensing end" of the fingers 55.

Activation sleeve 35 is chamfered around its leading edge to create an angled surface 90. In assembly, this chamfered surface 90 is positioned as close as possible to the complementary angled "head" surfaces 85 of the three jaws 55. This close positioning means that the dispensing pressure on the activation sleeve 35 can be reacted more quickly, since less distance is covered.

The needle hub 30 is provided with a complementary groove 70 around its circumference, such that the flange 65 is receivable in said groove 70 in the pre-dispense configuration. The location and shape of the groove 70 and the ledge 65 provide a very secure non-movable positioning of the needle hub, as the square shape of the ledge/groove combination prevents the hub 30 from moving in a forward or rearward direction.

An O-ring 75 is disposed around the outer circumference of the activation sleeve 35 and is positioned in an internal groove 80 in the inner surface of the gland 20. This provides a more effective seal around the hub/sleeve assembly to prevent fluid from escaping during injection.

The plunger 15 is formed as a hollow cylinder having an internal cavity 100. The end of the plunger barrel is sealed by a stopper 105 made of rubber and is held in place by a conventional retaining ring 110. A rubber gasket 115 is provided on the exterior of the plunger barrel and sealingly engages the interior surface of the barrel 10. The forward surface 120 of the stop is part spherical and the rear surface 125 of the needle hub 30 is shaped in a complementary manner to provide maximum drug delivery and minimum "dead space".

Referring to fig. 2, the syringe 200 according to the present invention is shown in a stage of injecting a liquid in the cavity 205 formed between the plunger 215 and the rear of the needle hub 225. The remaining components are as described in fig. 1. Furthermore, it is to be noted that an "air escape" hole 210 is provided in the plunger tube 215, which hole is required to enable air to escape when the mouthpiece is (subsequently) pushed into the cavity 205.

Referring to fig. 3, the syringe of fig. 2 is shown at the point of full injection, i.e., just as the plunger 315 applies pressure on the rear end 300 of the activation sleeve 335. When the activation sleeve 335 is pushed forward, it can be seen that the chamfered forward surface 390 comes into contact with the angled "head" surface 385 of the pawl 355 and begins to push the pawl away from the interface 330, thereby causing the flange 365 to begin to disengage from the groove 380 to release the spring 340.

Referring to fig. 4, the syringe of fig. 3 is shown after release of the retaining means. The spring 440 extends thereby pushing the needle hub 430 and the stop 505 well into the interior cavity 500 of the plunger. It can be seen that the needle 425 is also well pushed into the interior of the body of the syringe 405. At this point, the syringe can be safely handled without risk of needle stick injury.

It will be appreciated by a person skilled in the art that the above described embodiment is only one example of how the inventive concept can be implemented. It is to be understood that other embodiments may be conceived that differ from the present embodiment in details, yet fall within the same inventive concept and represent the same invention.

Claims

1. An auto-retractable syringe having a barrel and a plunger movable within the barrel, the barrel having a gland assembly disposed within a front portion thereof, a slide activated sleeve and a compression spring, the gland assembly being inserted into the barrel in a press-fit or screw-in manner and housing a movable needle hub to which a hypodermic needle is connected, the compression spring being disposed between the gland assembly and the needle hub so as to tend to push the needle hub into the barrel; wherein the plunger has a lumen capable of receiving the needle hub; wherein the needle hub is held in place prior to use by a retaining means which prevents movement of the needle hub into and out of the barrel; wherein the detent means comprises one or more square or rectangular detent regions in the needle hub having a profile which when engaged prevents movement of the needle hub inside or outside the barrel, and a set of resilient fingers having complementary square or rectangular flanges occupying the detent regions to lock the needle hub in place and against the force of the compression spring, wherein the slide activated sleeve fits around the needle hub and the partially compressed compression spring which contacts the needle hub and the slide activated sleeve, wherein the plunger, in combination with the slide activated sleeve, causes the detent means to release allowing the compression spring to push the needle hub into the interior cavity of the plunger; and

wherein the upper region of the resilient fingers has an inclined face that is inclined away from the needle hub, the slide activation sleeve is chamfered around its leading edge to create an angled surface, and in assembly the chamfered surface is positioned as close as possible to the complementary inclined surface of the resilient fingers, such that when the slide activation sleeve is engaged by the plunger moving in the injection direction, the applied force can thereby help push the resilient fingers away from the needle hub, thereby releasing the needle hub and enabling the compression spring to push the needle hub into the plunger.

2. The syringe of claim 1, wherein the plunger has a stop at its fluid-engaging end, the stop being held in place by a stop means, which can be overcome by the force of the compression spring pushing the needle hub into the plunger.

3. The syringe of claim 2 wherein said stop has a partially spherical fluid engaging surface.