AU2004101074A4 - Safety syringe with needle hub retracting mechanism - Google Patents

Safety syringe with needle hub retracting mechanism Download PDF

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Publication number
AU2004101074A4
AU2004101074A4 AU2004101074A AU2004101074A AU2004101074A4 AU 2004101074 A4 AU2004101074 A4 AU 2004101074A4 AU 2004101074 A AU2004101074 A AU 2004101074A AU 2004101074 A AU2004101074 A AU 2004101074A AU 2004101074 A4 AU2004101074 A4 AU 2004101074A4
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AU
Australia
Prior art keywords
needle hub
retracting
plunger
syringe
barrel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
AU2004101074A
Inventor
Can-Long Qiu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CLASSIC MEDICAL TECH (SHA) Co Ltd
Original Assignee
Classic Medical Tech Sha Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to TW200410053691.8 priority Critical
Priority to CNB2004100536918A priority patent/CN100382857C/en
Application filed by Classic Medical Tech Sha Co Ltd filed Critical Classic Medical Tech Sha Co Ltd
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Publication of AU2004101074A4 publication Critical patent/AU2004101074A4/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Description

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P001 Section 29 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Application Number: Lodged: Invention Title: Safety syringe with needle hub retracting mechanism The following statement is a full description of this invention, including the best method of performing it known to us: SAFETY SYRINGE WITH NEEDLE HUB RETRACTING MECHANISM

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a syringe and, more particularly to a safety syringe with a needle hub retracting mechanism.

2. The Prior Arts Medical personnel and medical waste processing personnel around the globe are frequently injured or even infected resulted from improper syringe operations. According to the statistics, there are over 1.3 million cases annually whose cause of death is directly related to unsafe injection. The direct medical expense involved has reached hundreds of million dollars.

Unsafe injection refers to an injection behavior, such as the reuse of a one-time syringe, flaws in aseptic manipulation, sharing needles, and improper waste processing, that is unsafe to the medical personnel, the public environment, and those patients taking the injection. Therefore, there are various types of safety syringes in the market nowadays.

In general, a conventional safety syringe usually has its needle hub installed at the neck of the syringe barrel and, when the injection is completed, the needle hub is retracted into the barrel. The shortcomings of the conventional syringe could be summarized as follows.

For conventional safety syringes of a first type, there is a metallic hook at the plunger's front end. After the injection, the plastic needle hub is grappled by the metallic hook and, when the plunger is pulled backward, the needle hub is retracted into the barrel. The advantage of this design is that, during clinical injection, the process of forcing the metallic hook into the needle hub would encounter less resistance, the user's hand would be less shaking when exerting a pushing force, and

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the patient would therefore feel less pain. On the other hand, the shortcomings of the Sdesign are as follows. Firstly, the adhesion of the metallic hook to the plastic plunger cannot withstand a separation force greater than 50 newtons. The foregoing grapple process also has a high error rate and the stability in terms of the syringe's safety function is compromised. During production, this type of syringes also has a limited yield. Secondly, the metallic hook could not be locked tightly with the needle hub.

Rotating the plunger could separate the metallic hook from the needle hub. Therefore, this type of syringes sometimes couldn't be destructed automatically after use and there is a high risk that the syringe is reused afterwards.

For safety syringes of a second type, there is an arrow-shaped plastic taper at the front end of the plunger. During the injection, the taper is forced into and tightly coupled with the needle hub. After the injection and when the plunger is pulled backward, the needle hub is retracted into the barrel. The advantage of this design is that the taper and the plunger are one whole plastic member of the syringe, and the needle hub is also made of plastic. The production of this type of syringes is therefore simpler and easier. As to the shortcomings, firstly, in the process of forcing the taper into the needle hub during clinical injections, a user has to at least double the pushing force so as to couple the taper and the needle hub together. The greater pushing force would cause the user's hand to shake and, as the needle is still within a patient's body, the patient would feel more pain. Secondly, the taper and the needle hub sometimes could not be coupled tightly together and a separation force grater than 45 newtons therebetween could separate them apart. In addition, since the needle hub and the taper are all made of plastic, making this type of syringes more difficult to be destructed automatically after use. There is again a high risk to reuse these syringes

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afterwards.

For safety syringes of a third type, the taper at the front of the plunger is actually a slanting rod. During the injection, the taper is pushed into the needle hub.

After the injection, the plunger is rotated first so as to lock the taper with the needle hub. Then, when the plunger is pulled backward, the needle hub is retracted into the barrel. The advantage of this design is that pushing the taper into the needle hub during clinical injections requires only an ordinary pushing force. The user's hand is N less shaking and the patient feels less pain. The taper and the plunger are one whole plastic member of the syringe, and the needle hub is also made of plastic. The production of this type of syringes is therefore simpler and easier. As to the shortcomings, firstly, to rotate the plunger to lock the taper with the needle hub, a medical staff sometimes needs to use both hands. However, in many practical circumstances, the medical staff simply cannot free both hands to complete the plunger rotation. On the other hand, if a user forgets to rotate the plunger and starts to pull the plunger backward, the taper would be detached from the needle hub. In addition, since the needle hub and the taper are both made of plastic, making this type of syringes less more difficult to be destructed automatically after use. There is still a high risk to reuse these syringes afterwards.

For safety syringes of a fourth type, the needle hub is embedded in the barrel with a replaceable needle. The needle hub encircles and attaches to a connecting rod positioned inside the barrel neck, and the needle is installed on the needle hub. A user could choose to use different types of needles based on practical requirement. A back end of the connecting rod has an arrow-shaped plastic inverted taper. A ring sealer is inserted between the connecting rod and the barrel neck so as to Sensure their airtightness and friction. A piston at the front end of the plunger has a

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cavity compatible with the inverted taper at the back end of the connecting rod.

ODuring injection, the inverted taper is forced into the piston's cavity. After injection, when the plunger is pulled backward, the connecting rod in the barrel neck and the needle hub are retracted back into the barrel. The advantages of the design are as follows. Firstly, during clinical injections, ordinary pushing force is enough for squeezing the arrow-shaped inverted taper into the piston's cavity. The user's hand wouldn't shake to add to the patient's pain. Secondly, the connecting rod and the C inverted taper are a whole plastic member. The cavity of the piston is also not simple.

The production is therefore quite straightforward. On the other hand, one of the shortcomings is that, as a ring sealer is used between the connecting rod and the barrel neck to provide the friction required, the friction therebetween generally wouldn't exceed 15 newtons. If a pulling force is greater than 15 newtons, the piston's cavity couldn't be able to grip the inverted taper at the back end of the connecting rod. The connecting rod would be separated from the plunger when the plunger is pulled, and the syringe's safety function is void. When a patient undergoes an intramuscular injection, the roughness and thickness of the patient's skin surface, along with the patient's muscular cramp, together would generate a friction as great as 20 newtons between the patient's skin and the syringe's needle. This type of syringes, therefore, frequently suffers needle being withdrawn into the barrel during clinical injections when the needle undergoes a friction greater than 15 newtons. This is a fatal drawback to this type of syringes as normal injection operations cannot be completed, and this is also why this type of syringes couldn't gain popularity in the market. Secondly, the inverted taper squeezed into the piston's cavity couldn't be locked firmly at its position and a separation force greater than 15 newtons could separate them apart.

After separation, the inverted taper and the piston both are still a whole member. This

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type of syringes is therefore difficult to be destructed automatically after use and there is a high risk to reuse these syringes afterwards.

For safety syringes of a fifth type, the syringe is composed of a barrel, a hollow plunger inside the barrel, a ring sealer around the front end of the plunger, and a needle hub with a needle installed inside the barrel neck at the front end of the barrel.

SA spring is installed around the needle hub's circumference and a piston is located on the front end of the plunger..The plunger piston and the back end of the needle hub are matched. After the injection, the needle hub is withdrawn into the hollow plunger under the effect of the spring and the plunger piston. This design also has some shortcomings as follows. This type of syringes has a more complex structure and some additional elements requiring more precise manufacturing process. Therefore, the production of this type of syringes has a limited yield and a much higher production cost. In addition, all elements of this type of syringes are whole members and are more difficult to get destructed automatically after use. There is a high risk to use the syringes afterwards.

SUMMARY OF THE INVENTION An objective of the present invention is to provide a safety syringe that has a simple and reasonable structure, is easy to manufacture with fewer manufacturing steps, and can effectively control production cost. In addition, the syringe's safety function has an extremely high stability when it is put to clinical use, and there is very little residual fluid after injection. The syringe according to the present invention, therefore, not only overcomes the conventional safety syringes' insufficient structural design, but also achieves the syringe's forced destruction after use to avoid its reuse.

To reach the foregoing objectives, the syringe according to the present 0 invention utilizes a retracting mechanism. The syringe mainly contains a barrel, a plunger slidably mounted inside the barrel, a piston attached to a front end of the _plunger, and a needle hub with a needle installed at a front end of the barrel. The syringe is characterized in that a retracting rod is installed at the front end of the plunger, a cross groove is on a front portion of the retracting rod, and a retracting Otongue is installed in the groove.

Unlike conventional syringes' design concept, the syringe of the present invention utilizes a structurally simple metallic wire or metallic band to fulfill the syringe's safety requirement. Additionally, the syringe according to the present invention could effectively overcome manufacturing difficulties, reduce the number of manufacturing steps, shorten processing time, enhance production performance and quality, and control production cost effectively. In summary, the syringe according to the present invention has the following advantages: reasonable structure design, high safety, forced destruction, low residual fluid, less difficult to manufacture, fewer processing steps, reduced cost, easy to produce and popularize.

The foregoing and other objects, features, aspects and advantages of the present invention will become better understood from a careful reading of a detailed description provided herein below with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the structure of a syringe according to the present invention.

FIG. 2 is a schematic diagram showing the structure of the retracting rod of the present invention.

SFIG. 3 is a side view of the retracting rod depicted in FIG. 2.

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NI FIG. 4 is a schematic diagram showing the structure of a first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a first embodiment of the present invention when the injection is completed.

r FIG. 6 is schematic diagram showing a first embodiment of the present invention when the plunger is pulled backward.

FIG. 7 is a schematic diagram showing the structure of a second embodiment of the present invention.

FIG. 8 is a schematic diagram showing the structure of a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, detailed description along with the accompanied drawings is given to better explain preferred embodiments of the present invention.

Please be noted that, in the accompanied drawings, some parts are not drawn to scale or are somewhat exaggerated, so that people skilled in the art can better understand the principles of the present invention.

FIG. 1 is a schematic diagram showing the structure of a syringe according to the present invention. As shown in FIG. 1, the syringe, similar to conventional syringes, contains a hollow barrel 1, a plunger 2 slidably mounted inside the barrel 1, and a piston 7 attached to a front end of the plunger 20, and a needle hub 3 with a needle 4 installed at a front end of the barrel 1. In sum, the present invention adds a number of additional elements, in addition to the foregoing elements, and utilizes a special structural design in a conventional syringe to achieve the objectives of the present invention. The additional elements provided by the present invention contain at least a retracting rod 5 at the front end of the plunger 2, and a retracting

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N tongue 6 on the retracting rod 5. Additionally, the special structural design of the Spresent invention requires that the needle hub 3 is detachable from the barrel 1, so that the retracting tongue 6 could retract the needle hub 3 and the needle 4 back into the barrel 1. In the following, how the needle hub 3 is tightly coupled to the retracting r tongue 6 and gets retracted back by the plunger 2 and the retracting rod 5 is described in details.

Please refer to FIGS. 2 and 3. FIG. 2 is a schematic diagram showing the

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structure of the retracting rod 5 of the present invention, while FIG. 3 is a side view of the retracting rod 5 depicted in FIG. 2. As shown in FIGS. 2 and 3, the retracting tongue 6, which is a metallic wire or a metallic band, is installed inside a cross groove 8 near a front end of the retracting rod 5. Behind the grove 8 and on the surface of the retracting rod 5, there are two symmetrical slopes 9 slant toward the groove 8 and into the retracting rod According to the present invention, the retracting rod 5 should have a cross-sectional diameter smaller than that of the needle hub 3's inwall, the slopes 9 should have a width smaller than that of the retracting rod 5's diameter, and the two slopes 9 should have an angle between 50 and 60* therebetween. Therefore, when a user of the syringe pushes the plunger 2 forward, the injection fluid within the barrel 1 is injected into a human body and, when the injection fluid is about to be consumed, the retracting rod 5 is pushed into the needle hub 3 whose inwall causes the retracting tongue 6 to deform. Before being pushed into the needle hub 3, the retracting tongue 6, if implemented as a metallic wire, could have a straight shape, a U shape, or an n shape. Similarly, if the retracting tone is implemented as a metallic band, it could also have a flat shape, a U shape, or an n shape. Also the two shorter ends of the metallic band could have barbs. In various embodiments, the needle 4 could be either Sreplaceable or irreplaceable.

SFIG. 4 is a schematic diagram showing the structure of a first embodiment of the present invention. As shown in FIG. 4, the present embodiment is a 3ml syringe with irreplaceable, embedded needle hub 3. More specifically, the needle hub 3 is installed inside the barrel neck in the front of the barrel 1. The gap between the needle hub 3 and the barrel neck is sealed to avoid leakage. So far, the 3ml syringe adopts a conventional structure and therefore further description is omitted here..

SThe retracting tongue 6 of the present embodiment is a straight metallic wire. The two slopes 9, as depicted in FIG. 2, form a 50* angle. When the plunger 2 is pushed forward, the injection fluid is driven out through the needle 4 by the piston 7.

Since the retracting rod 5 has a cross-sectional diameter smaller than that of the needle hub 3's inwall, a front portion of the retracting rod 5 would enter the inner room of the needle hub 3, when the plunger 2 is pushed for a certain distance into the barrel 1. From this moment on, if the plunger 2 is pushed forward further, as the retracting tongue 6 has a length greater than the diameter of the needle hub 3's inwall, the retracting tongue 6's straight metallic wire would be bended backward by the needle hub 3 and would become an N shape when it is forced into the inner room of the needle hub 3, as depicted in FIG. 5. Because of its metallic material, the N-shaped retracting tongue 6 would exert an outward force against the inwall of the needle hub 3. When the injection is completed when the plunger 2 cannot be pushed forward further) and when the plunger 2 is pulled backward, the plunger 2 drags along with it the retracting rod 5 backward, further causing the bended metallic wire's two ends to stuck deeply into the needle hub 3's inwall.

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FIG. 6 is schematic diagram showing a first embodiment of the present invention when the plunger 2 is pulled backward. As shown in FIG. 6, when the Splunger 2 is pulled backward, the needle hub 3 and the needle 4 are retracted together into the barrel 1 and the syringe is, thereby, damaged and cannot be used again. The present invention therefore could effectively achieve injection safety by preventing medical personnel from getting injured and infected mistakenly.

FIG. 7 is a schematic diagram showing the structure of a second embodiment of the present invention. As shown in FIG. 7, the present embodiment is a N 5ml syringe with the two slopes 9 forming a 40' angle and the retracting tongue 6 having an N shape. Similar to the previous embodiment, the plunger 2 is pushed forward and the retracting tongue 6 is forced into the needle hub 3. When the injection is completed and the plunger 2 is pulled backward, the two ends of the retracting tongue 6's N-shaped metallic wire get stuck deeply into the needle hub 3's inwall. The needle hub 3 and the needle 4 again would be retracted into the barrel 1 and the injection safety is thereby persevered.

FIG. 8 is a schematic diagram showing the structure of a third embodiment of the present invention. As shown in FIG. 8, the present embodiment is a 3ml syringe with the two slopes 9 forming a 25* angle and the retracting tongue 6 having a U shape. Similar to the previous embodiments, the plunger 2 is pushed forward and the retracting tongue 6 is forced into the needle hub 3, causing the retracting tongue 6's U-shaped metallic wire to bend backward. When the injection is completed and the plunger 2 is pulled backward, the two ends of the retracting tongue 6's N-shaped metallic wire get stuck deeply into the needle hub 3's inwall. The needle hub 3 and the needle 4 again would be retracted into the barrel 1 and the injection safety is thereby persevered.

-Although the present invention has been described with reference to the 0 N preferred embodiments, it will be understood that the invention is not limited to the Sdetails described thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art.

Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.

Claims (4)

1. A safety syringe, comprising: Sa barrel; a plunger slidably mounted inside said barrel; a piston attached to a front end of said plunger; and a needle hub with a needle installed at a front end of said barrel, said safety syringe characterized in a retracting rod installed at a front end of said plunger, a cross groove on a front portion of said retracting rod, and a retracting tongue positioned in said groove.
2. The syringe according to claim 1, further characterized in symmetrical slopes located behind said groove and on a surface of said retracting rod, said slopes having a width smaller that of said retracting rod's diameter, said slopes forming an angle between 50 and 60 therebetween.
3. The syringe according to claim 1, further characterized in said retracting tongue composed of an metallic wire having one of the following shapes: a straight shape, a U shape, and an N shape.
4. The syringe according to claim 1, further characterized in said retracting tongue composed of an metallic band having one of the following shapes: a straight shape, a U shape, and an N shape, said metallic band having barbs at said metallic band's shorter ends.. The syringe according to claim 1, characterized in said retracting rod having a cross-sectional diameter smaller than that of said needle hub's inwall. DATED this 17th day of December 2004. CLASSIC MEDICAL TECH(SHA)CO., LTD. WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VIC 3122.
AU2004101074A 2004-08-12 2004-12-17 Safety syringe with needle hub retracting mechanism Ceased AU2004101074A4 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
TW200410053691.8 2004-08-12
CNB2004100536918A CN100382857C (en) 2004-08-12 2004-08-12 Clamp spring type safe injector

Publications (1)

Publication Number Publication Date
AU2004101074A4 true AU2004101074A4 (en) 2005-02-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
AU2004101074A Ceased AU2004101074A4 (en) 2004-08-12 2004-12-17 Safety syringe with needle hub retracting mechanism

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CN (1) CN100382857C (en)
AU (1) AU2004101074A4 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2448384Y (en) * 2000-11-22 2001-09-19 沈挺 Safety syringe capable of being destroyed while drawing back
CN2528460Y (en) * 2002-04-01 2003-01-01 沈挺 Safety syringe capable of changing needle
US6613016B1 (en) * 2003-01-21 2003-09-02 Jen Chuan Ku Safety hypodermic syringe
CN2714073Y (en) * 2004-08-12 2005-08-03 上海特杰德医疗科技有限公司 Snap spring type safe syringe

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Publication number Publication date
CN100382857C (en) 2008-04-23
CN1733324A (en) 2006-02-15

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