AU735953B2

AU735953B2 - A retractable and destructible safety syringe

Info

Publication number: AU735953B2
Application number: AU49238/97A
Authority: AU
Inventors: Wen-Neng Liu
Original assignee: LIFE-SHIELD PRODUCTS Inc
Current assignee: LIFE-SHIELD PRODUCTS Inc
Priority date: 1997-12-23
Filing date: 1997-12-23
Publication date: 2001-07-19
Anticipated expiration: 2017-12-23
Also published as: FR2772621B1; DE29800200U1; BR9800676A; FR2772621A1; GB9727303D0; GB2332628A; GB2332628B; AU4923897A; CA2223188A1; ZA98169B

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT U Name of Applicant: Actual Inventor(s): Address for service is: Wen-Neng Liu Wen-Neng Liu WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: "A Retractable and Destructible Safety Syringe The following statement is a full description of this invention, including the best method of performing it known to me:- "A Retractable and Destructible Safety Syringe" Background of the Invention The present invention relates to a retractable and destructible safety syringe which has simple structure and can be easily manufactured at low cost and commercialised.

Various types of disposable syringes are widely used nowadays. After being discarded, a large number of such syringes result in problem of pollution of :environment. In addition, the used syringes often impale medical personnel and infect the personnel with viruses or bacteria carried by the patients. Especially, in case the medical personnel are infected with AIDS virus, the personnel may die innocently.

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*9*o In order to solve these problems, various types of retractable syringes have been developed. For example, a spring has been installed between the syringe barrel and the piston for pulling the needle back into the barrel after injection. However, 15 due to the nature of the liquid medicine used, the material of the spring is strictly limited to avoid contamination. Therefore, the structure of such syringes is complicated and the manufacturing cost is very high. Various types of safety *OIII syringes free from the springs have been also developed. In such syringes, a latch member is disposed at the bottom of the barrel, whereby when the plunger is pushed at the bottom of the barrel, the latch member latches the plunger with the needle. Therefore, when the plunger is pulled back, the needle is retracted into the barrel along with the plunger so as to avoid injury of medical personnel.

In order to avoid leakage of the liquid medicine and unexpected dropping of the needle from the barrel, the needle must be firmly assembled with the barrel.

However, where the needle is excessively firmly retained in the barrel, it will be difficult to pull the needle back into the barrel. Therefore, it is difficult to have both situations.

-3- In addition, it is generally the case in circumstances where it is necessary to securely latch the plunger with the needle to effect withdrawal of the needle, it is relatively difficult to adequately engage the plunger with the needle to effect the required latching. Conversely, generally in cases where it is easy to latch the plunger with the needle, the plunger will be inevitably unreliably engaged with the needle and such engagement will be insufficient for pulling the needle back into the barrel. Therefore there has been a difficulty in the part in effecting an easy engagement between the plunger, the needle and a secure engagement therebetween.

Moreover in the case of retractable syringes, it is often the case that before the injection is completed, the plunger is inadvertently latched with the needle. This will lead to waste of the needle.

The preceding discussion of the background to the invention is intended only to S:.i facilitate an understanding of the present invention. It should be appreciated that oo 15 the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the ogl priority date of the application.

Summary of the Invention It is therefore a desirable object of the present invention to provide a retractable and destructible safety syringe which can avoid leakage of liquid medicine and prevent the needle from accidentally dropping out of the barrel. Also, the needle can be easily pulled back into the barrel.

It is a further desirable object of the present invention to provide the above safety syringe in which the plunger can be easily and firmly latched with the needle when injection is completed and that the needle can be reliably pulled back into the barrel.

-4- It is still a further desirable object of the present invention to provide the above safety syringe in which before the injection is completed, the needle is prevented from being latched by mistake.

Accordingly the invention resides in a retractable and destructible safety syringe comprising: a syringe barrel having a first and second end and formed with an internal chamber, the first end having a needle socket defining a needle holder o cavity; b e .1 a plunger having a first and second end, the first end having a piston to 10 slidably and sealing received within the barrel; a needle holder having a first and second end, the needle holder being sealing and slidably received in the needle holder cavity; S" jfirst end of the needle holder being adapted to support a needle; a needle retracting means located at adjacent ends of the plunger and 15 needle holder, the retracting means including a detent supported from one adjacent end and a clip means supported from the other adjacent end, the detent having a central axis and a first annular radial surface remote from the other adjacent end; the clip means comprising an annular array of clip members coaxial with the central axis, each clip member being supported at a first end from the other adjacent end, the clip members being spaced angularly about the central axis, the clip members each having a second end, the clip members being capable of resilient deformation towards and away from the central axis, each second end having a second radial surface, the clip members being moveable past the detent on movement of the adjacent ends into close engagement and resilient radial deformation of the clip _members to cause the radial reinforcer to become interengaged wherein interengagement of the radial reinforcers will prevent movement of the adjacent ends from said close engagement and wherein when the adjacent ends are in said close engagement the detent is capable of some limited relative axial movement towards the other adjacent end.

According to a preferred feature of the invention a sealing ring is provided in the needle holder cavity and/or the needle holder according to a further preferred feature of the invention. According to one embodiment both the inner wall of the needle holder cavity and the outer wall of the needle holder support sealing fixing o rings.

10 According to a preferred feature of the invention the syringe includes a latch :plate having a first and second end, the first end being pivotally connected at or adjacent the second end of the syringe barrel, a first latch portion provided at the second end of the latch plate, a second latch portion provided at or adjacent the second end of the plunger, said latch portions being interengagable when the 15 adjacent ends are in close engagement to resist relative axial movement between the plunger and the syringe barrel.

•The present invention can be best understood through the following description •and accompanying drawings of several preferred embodiments, wherein: Brief Description of the Drawings Figure 1 is a perspective exploded view of a first embodiment of the present invention; Figure 2 is a perspective assembled view of the first embodiment of Figure 1; Figure 3 is a perspective bottom view showing the needle and the needle holder of the first embodiment; Figure 4 is a sectional view showing that the liquid medicine is sucked into the syringe barrel of the first embodiment; -6- Figure 5 is a sectional view showing that the liquid medicine is completely injected and the detent disposed on the piston is latched with the clip member disposed on the needle holder; Figure 6 is a front view showing that the liquid medicine is about to be completely injected and the detent is passing through the clip member; Figure 7 is a front view showing that the detent has passed through the clip member and is gripped thereby;

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Figure 8 is a sectional view showing that the injection is completed and the needle is pulled back into the barrel and automatically tilts laterally; Figure 9 is an enlarged view of area 9 denoted by phantom line of Figure 7, in which the plunger is pulled downward and two clip members simultaneously clip the plunger; Figure 10 is a sectional view showing that after the needle is pulled back into the barrel, the plunger is again pushed forward to bend and damage the needle; 15 Figure 11 is a sectional view of a second embodiment of the present invention, in which the liquid medicine is sucked into the barrel; Figure 12 is a front view of the needle and the needle holder of the second embodiment; Figure 13 is an enlarged bottom view of the needle and the needle holder of the second embodiment; Figure 14 is a sectional view according to Figure 12, showing that the liquid medicine is completely injected and the clip member disposed on the plunger is latched with the detent disposed on the needle holder; -7- Figure 15 is a front view of the needle and the needle holder of a third embodiment of the present invention; Figure 16 is an enlarged bottom view of the needle and the needle holder of the third embodiment; and Figure 17 is a sectional view according to Figure 15, showing that the liquid medicine is completely injected and the clip member disposed on the plunger is latched with the detent disposed on the needle holder.

Detailed Description of the Preferred Embodiments The first embodiment is described with reference to Figures 1 to The safety syringe 20 of the first embodiment includes a syringe barrel 21, a plunger 22, a needle holder 23 and a needle 24. The syringe barrel 21 has a first and a second ends 28, 29 and is formed with an internal chamber 27. The first end 28 is formed with a needle socket 30 defining a needle holder cavity 31.

An annular shoulder 33 is formed between the internal wall of the chamber 27 15 and the cavity 31.

The plunger 22 has a first and a second ends 34, 35. The first end 34 supports a piston 36 sealingly received in the barrel 21. The plunger 22 has a first central axis 47.

The needle holder 23 has a first and a second ends 37, 38. The second end 38 comprises a tubular boss 60 which in use is positioned to be received in the internal chamber 27 of the first end 28 of the barrel 21. The needle holder 23 has a second central axis 48 which is received with the central axis 47 of the plunger. The needle 24 is inserted into the first. end 37 of the needle holder 23.

The body of the needle holder between the ends 37 and 38 is dimensioned to be snugly received in the needle holder cavity 31. To sealingly and positively 4 1 1.

-8engage the needle holder within the cavity, sealing rings 32 are fixed to the body of the needle holder.

Referring to Figs. 3 to 9, the needle retracting means of the embodiment includes two clip members 25 and 25' provided on the second end of the needle holder.

The clip members are supported from the internal wall of the tubular boss The needle retracting means further comprise detent 26 on the first end 34 of the plunger. The clip members 25 and 25' each have a first and a second ends 49 and 50. The first end 49 is fixed to the internal wall of the tubular boss adjacent the second end 38 of the needle holder 23. The distance between the S: 10 first end 49 of the clip members 25 or 25' and the first and second central axes 47, 48 is defined as a first distance 51 (see Figure The clip members :converge inwardly within the tubular boss towards the first end. In a free state, the distance between the second end 50s of the clip members 25 or 25' and of the first and second central axes 47, 48 is defined as a second distance 52 (see Figure The second distance 52 is less than the first distance 51. The distance between the second end 50 of the clip members 25 and 25' and the inner end 61 of the tubular boss 60 is defined as a third distance 62. The distance between the first end 49 of the clip members 25 and 25' and the inner *end 61 of the tubular boss 60 is defined as a fourth distance 63. The third ooo 20 distance 62 is less than this fourth distance 63.

The detent 26 has a first and a second ends 53, 54. The first end 53 of the detent is fixed on the first end 34 of the plunger 22 and is coaxial with the central axes 47, 48 of the plunger 22 and the needle holder 23 and is formed as a stem 58 supporting an enlarged portion 55. The enlarged portion comprises a radial surface 55 which faces the first end 34 of the plunger and is spaced from the outer end of the detent. The detent is formed with a converging conical surface between the radial face and the outer end of the detent: When the first end 34 of the plunger 22 is pushed into close engagement with the first end 28 of the barrel 21, the enlarged portion 55 of the detent 26 engages and slides past the second ends 50 of the clip portions 25 and 25'. As a result, -9the clip portions 25 and 25' resiliently flex outwardly and when the radial surface 56 moves past the second ends 50 they flex inwardly to clampingly engage with the stem 58. When the plunger 22 is then pulled from the first end 28 of the barrel 21 towards the second end 29 thereof, the radial surface 56 of the enlarged portion 55 abuts against the second end 50 of the clip members 25 and This forces the second end 50s of the clip members 25 and 25' toward the centre of the detent 26 in a direction shown in Figure 9 by the arrows 57 and 57' respectively, so that they move firmly engage with the stem 58 against the radially extending surface 56 of the enlarged portion 55. As a result the needle 10 holder 23 and the needle 24 can be together pulled into the barrel 21 on application of a suitable force to the second end 35 of the plunger.

oo• Referring to Figs. 1 and 2, the safety syringe 20 of the present invention further includes an insurance latch plate 41 which provides a first latch section 42. A second latch section 43 is provided on the second end 35 of the plunger. The 15 insurance latch plate 41 has a first and a second ends 45, 46. The first end 45 is hingedly connected with the second end 29 of the barrel 21. The first latch section 42 is disposed at the second end 46 of the insurance latch plate 41. The second latch section 43 is disposed at the second end 35 of the plunger 22. The second latch section 43 can be latched with the first latch section 42 so as to locate the first end 34 of the plunger close to but spaced from the first end of the barrel 21 so that the detent 26 does not engage the clip member and to prevent the detent 26 from engaging with the clip members 25 by mistake.

As shown in Figs. 1 to 4, prior to use, the needle 24 is installed in the needle holder cavity 31 of the insertion socket 30 of the barrel. The sealing fixing ring 39 of the needle holder 23 is tightly and firmly engaged with the sealing fixing ring 32 of the inner wall of the cavity 31. A needle sheath 44 is fitted around the needle 24. The plunger 22 and the piston 36 are fitted into the internal chamber 27 of the barrel 21. The first latch section 42 of the insurance latch plate 41 is latched with the second latch section 43 of the second end 35 of the plunger 22.

As a result the detent 26 is held in a position close to, but separated from the clip members 25 and When the first end 34 of the plunger is closely engaged with the first end of the barrel and the detent is engaged with the clip member, the clip members 25 and are loosely engaged with the detent 26 so that after the tip 40 of the needle 24 is pulled back into the interior of the barrel 21 (as shown in Figure the tip 40 will laterally tilt due to instability. At this time, the tip 40 is positioned under the shoulder section 33 of the barrel 21. The shoulder section 33 serves to stop the tip 40 and will cause the needle 23 to be bent (as shown in Figure 10) when the plunger is pushed inwardly into the barrel.

When injecting, an operator thrusts the needle 24 into a liquid medicine bottle.

10 Then the insurance latch plate 41 is unlatched, permitting the plunger 22 to be pulled outward for sucking the liquid medicine into the barrel 21 (as shown in Figure Then the needle 24 is directed upward and the plunger 22 is slightly pushed upward to exhaust the air on upper portion of the barrel 21 from the tip of the needle 24. After the injection is completed, as shown in Figs. 5 and 9, .ooooi 15 the plunger 22 is pushed to the bottom of the barrel. At this time, the enlarged part of the detent 26 can easily push past the clip members 25 and 25' and of the second ends 50. The clip members 25 and 25' will then resiliently clamp against the stem 58 of the detent 26 inward of the radial surface 56. Then, as shown in Fig. 7, when the plunger 22 is pulled back, the two clip members 25 and 25' are depressed by the radial surface 56 of the detent 26 and are respectively rotated about their second ends 49 in the directions shown by the arrows 57 and 57'. At this time, the opposed clip members 25 and 25' simultaneously firmly clamp the stem 58 of the detent 26. The greater the pulling force applied by the plunger 22 to the needle holder 23, the greater the clamping force that is applied by the clip members 25 and 25' to the detent 26. Therefore, the clip members 25 and can very firmly clamp the stem 58 and the radially extending surface 56 of the detent 26 without loosening (as shown in Fig. 9).

As shown in Fig. 8, after the needle 24 lies within the barrel 21, and in the absence of any force being applied by the plunger the clip members 25 and are loosely engaged with the stem 58 of the detent 26 so that the needle 24 is A' able to laterally tilt due to instability. At this time, the tip 40 of the needle is -11positioned under the shoulder section 33 of the barrel 21. In addition, the small diameter tail end 60 of the needle sheath 44 originally fitted around the needle holder 23 can then be inserted into the needle holder cavity 31 to seal the same.

Therefore, the tip 40 of the needle 24 is prevented from unexpectedly protruding out of the needle holder cavity 31. Finally, as shown in Fig. 10, the plunger 22 is pushed forward to press the tip 40 against the shoulder 33 of the barrel 21 in order to bend and destroy the needle 24 and prevent it from moving from the barrel through the needle holder cavity 31.

Figs. 11 to 14 show a second embodiment of the present invention, in which the 10 operation procedure is identical to that of the first embodiment. The difference between the two embodiments only resides in that the positions of the clip members 25 and 25' and the detent 26 are exchanged.

Referring to Figs. 15 to 17, as necessary, both of the inner wall of the needle .l.l.i holder cavity 31 of the barrel 21 and the outer wall of the needle holder 23 can o* 15 be disposed with one or more sealing fixing rings 32, 39 fitted with each other.

According to the above arrangement, the present invention has the following advantages: 1. The safety syringe can avoid leakage of liquid medicine and prevent the needle from accidentally dropping out of the barrel. Also, the needle can be easily pulled back into the barrel.

2. The plunger can be easily firmly latched with the needle and the needle can be also reliably pulled back into the barrel.

3. Before the injection is completed, the needle is prevented from being latched by mistake.

It is to be understood that the above description and drawings are only used for illustrating some embodiments of the present invention, not intended to limit the scope thereof. Any variation and derivation from the above description and -12drawings should be included in the scope of the present invention.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", 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.

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Claims

1. A retractable and destructible safety syringe comprising: a syringe barrel having a first and second end and formed with an internal chamber, the first end having a needle socket defining a needle holder cavity; a plunger having a first and second end, the first end having a piston which is slidably and sealing received within the barrel to be slidable axially in the ."barrel; o. a needle holder having a first and second end, the needle holder being sealing and slidably received in the needle holder cavity to be slidable axially fee: 10 is the needle holder cavity; *o.*oo* S"first end of the needle holder being adapted to support a needle; 9*o* a needle retracting means located at adjacent ends of the plunger and needle holder, the retracting means including a detent supported from one 9 adjacent end and a clip means supported from the other adjacent end; a first annular radial surface remote from the other adjacent end; the clip means comprising an annular array of clip members coaxial with the detent, the clip members being spaced angularly about a central axis, each clip member being supported at a first end from the other adjacent end, the clip members each having a free second end, the clip members being capable of resilient deformation towards and away from the central axis, each second end having a second radial surface; the clip members being moveable past the detent on movement of the adjacent ends into close engagement and resilient radial deformation of the clip members to cause the radial surfaces to become interengaged, wherein Sinterengagement of the radial surfaces will prevent movement of the adjacent -14- ends from said close engagement and wherein when the adjacent ends are in said close engagement the detent is capable of some limited relative axial movement towards the other adjacent end and rotational movement about transverse axes intersecting the retracting means.

2. A retractable and destructible safety syringe as claimed at claim 1 wherein the detent further comprises a stem extending axially from the one adjacent end, the stem having an enlarged portion at its outer end, said enlarged portion being defined in part by said first radial surface which is located at the innermost end of the enlarged portion and further by a convergent surface between the outer radial edge of the first radial surface and the outer end of the enlarged portion, each clip member being obliquely convergent from the o first end, the inner diameter of the annular array of first ends of the clip •0o; members being greater than the outer diameter of the first radial surface and the inner diameter of the annular ray of second ends being less than the outer diameter of the first radial surface, said second radial surface being provided by the axial face of the second ends. S" S

3. A retractable and destructible safety syringe as claimed at 2 wherein inner S diameter of the annular array of second ends is less than the thickness of the stem.

4. A retractable and destructible safety syringe as claimed at claim 2 or 3 wherein on interengagement of the radial surfaces on application of an axial force therebetween to cause separation will cause a radial inward force to be applied to the second ends.

A retractable and destructible safety syringe as claimed at claim 1 wherein the detent comprises an annular formation provided at the one adjacent end and wherein said clip means are receivable through the annular formation, the second end of each clip member being provided with a radial formation, the radial formations of the clip members jointly defining said second radial Ssurface which is outwardly directed at a position spaced axially inwardly from S the second end, the outer surface of the clip members between the second radial surface and second end being jointly convergent wherein the surface of the clip means defined by the second ends is less than the inner diameter of the first radial surface and the outer radial surface of the second radial surface is greater than the inner diameter of the first radial surface.

6. A retractable and destructible safety syringe as claimed at any one of the preceding claims wherein said clip means comprises at least two clip members.

7. A retractable and destructible safety syringe as claimed at any one of the preceding claims wherein a sealing fixing ring is provided in the needle holder cavity to sealingly and slidingly engage the needle holder. !ii:

8. A retractable and destructible safety syringe as claimed at any one of claims 2 to 6 wherein a sealing fixing ring is provided in the needle holder to slidingly and sealingly engage the needle holder cavity. 000

9. A retractable and destructible safety syringe as claimed at 7 or 8 wherein a plurality of sealing fixing rings are provided. OOIOI=

10. A retractable and destructible safety syringe as claimed at any one of claims 8 and 9 wherein a sealing fixing ring is supported from the needle holder cavity and a second sealing fixing ring is supported from the needle holder to effect sealing and slidable engagement of the needle holder within the needle 20 holder cavity.

11. A retractable and destructible safety syringe as claimed at any one of the preceding claims including a latch plate having a first and second end, the first end being pivotally connected at or adjacent the second end of the syringe barrel, a first latch portion provided at the second end of the latch plate, a second latch portion provided at or adjacent the second end of the plunger, said latch portions being interengagable when the adjacent ends are F spaced from said close engagement to resist relative axial movement between the plunger and the syringe barrel. 0 1., -16-

12. A retractable and destructible safety syringe substantially as herein described. Dated this eleventh day of May 2001 Wen-Neng Liu Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant o **o