Hypodermic syringes

• US 6,706,019 B1
• Filed: 05/17/2001
• Issued: 03/16/2004
• Est. Priority Date: 09/25/1998
• Status: Expired due to Fees

• Current Assignee: C-Major Ltd.
• Original Assignee: Colin H. Burgess, David W. Parker
• Inventors: Parker, David W., Burgess, Colin H.
• Primary Examiner(s): Mendez, Manuel
• Assistant Examiner(s): Han, Mark K.
• Application Number:
  US09/787,813
• Time in Patent Office: 1,034 Days
• Field of Search: 604/198, 604/192, 604/110, 604/220, 604/194, 604/187, 128/919
• US Class Current: 604/198
• CPC Class Codes: A61M 2005/3104 Caps for syringes without needle
• CPC Class Codes: A61M 2005/3231 Proximal end of needle captured or embedded inside piston head, e.g. by friction or hooks
• CPC Class Codes: A61M 2005/3235 triggered by radial deflection of the anchoring parts between needle mount and syringe barrel or needle housing, e.g. spreading of needle mount retaining hooks having slanted surfaces by engagement with correspondingly shaped surfaces on the piston at the end of an injection stroke
• CPC Class Codes: A61M 2005/3241 Needle retraction energy is accumulated inside of a hollow plunger rod
• CPC Class Codes: A61M 2005/342 Off-center needles, i.e. needle connections not being coaxial with the longitudinal symmetry axis of syringe barrel
• CPC Class Codes: A61M 5/31501 Means for blocking or restricting the movement of the rod or piston A61M5/5013 takes precedence
• CPC Class Codes: A61M 5/3202 Devices for protection of the needle before use, e.g. caps A61M5/50 takes precedence; for infusion spikes A61M5/1626; protectors for sharps A61B50/3001
• CPC Class Codes: A61M 5/3234 Fully automatic needle retraction, i.e. in which triggering of the needle does not require a deliberate action by the user
• CPC Class Codes: Y10S 128/919 Syringe, means to protect user

Abstract

A disposable hypodermic syringe, which is provided with the needle fitted and sheathed, provides automatic retraction of the needle after use. The syringe may be supplied pre-charged with an injectant. The completion of the injection stroke attaches the piston to the needle carrier and subsequently dislodges a retaining ring thereby freeing the piston from the plunger and releasing stored energy of a spring or the like to draw the piston and needle carrier into the plunger. The plunger is positively retained inside the housing by the interaction of rings. Alternative methods of locating the needle carrier during use and of attaching the piston to the needle carrier to enable retraction are shown. An alternative method of retaining the piston on the plunger is also shown. A further configuration is shown affording the use of an offset needle. The syringe has optional features to prevent unwanted inward movement of the plunger and to prevent seepage of liquid after use.

Claims

1. A hypodermic syringe including a housing, a plunger, a needle carrier with a needle mounted thereto positionable during assembly of the syringe within the housing with the needle extending therefrom, sealing means for defining a seal carrier and the housing, a sheath mounted to the needle carrier and surrounding the needle, and stored energy means, wherein the plunger and stored energy means are configured such that when the syringe is used and the plunger reaches the needle carrier, the plunger becomes attached to the needle carrier and the stored energy in the stored energy means is released to retract the needle carrier and the needle into the housing, the housing being configured such that the seal is formed between the needle carrier and the housing during assembly and such that the needle carrier with the needle mounted thereto is positionable during assembly of the syringe through the housing with the needle pre-sheathed.

2. A syringe as claimed in claim 1, wherein the plunger comprises a casing and a piston located and movable within the casing.

3. A syringe as claimed in claim 2 wherein the piston includes means for engagement with the needle carrier.

4. A syringe as claimed in claim 3 wherein the engagement means comprises either a male or female member on the head engaging with a corresponding male or female member on the needle carrier.

5. A syringe as claimed in claim 4 wherein the engagement means comprises a projection formed on the piston and the needle carrier comprises a number of spring biased arms which are retained in position by a collar, the collar being displaceable by the projection on the head such that the arms engage behind the projection thereby attaching the needle carrier to the piston.

6. A syringe as claimed in claim 3 wherein the needle carrier includes a cup which is retained in position by a lip formed on the housing, and a projection on the piston is engageable with cup so as to release the cup from engagement with the lip, and the cup has a lip which engages behind the projection thereby joining the needle carrier to the piston.

7. A syringe as claimed in claim 3 in which the needle carrier includes a number of deflectable arms which are engageable with an opening in the piston so as to join the needle carrier with the piston.

8. A syringe as claimed in claim 7 in which the needle carrier has at least one projection engaging with a lip to retain the needle carrier to the housing of the syringe prior to displacement of the deflectable arms, displacement of the deflectable arms releasing the needle carrier from the housing.

9. A syringe as claimed in claim 3 wherein the means for engagement with the needle carrier includes a fluid passage to prevent fluid lock.

10. A syringe as claimed in claim 1 wherein the stored energy means comprises a spring co-operating between the piston and the casing and having a releasable retaining means in order to release the energy stored within the spring.

11. A syringe as claimed in claim 10 wherein the releasable retaining means comprises a ring located on the piston which is disengageable from the piston as a result of pressure exerted on the plunger after completion of an injection stroke.

12. A syringe as claimed in claim 10 in which the releasable retaining means comprises a lip on the casing which co-acts with a circular ridge formed on the piston.

13. A syringe as claimed in claim 10, wherein the spring is a tension or compression spring.

14. A syringe as claimed in claim 1 wherein the plunger and the housing are formed with means for engaging one another so as to prevent removal of the plunger from the casing.

15. A syringe as claimed in claim 14 wherein the plunger is provided with at least one projection which is engageable with a corresponding lip on the housing.

16. A syringe as claimed in claim 1, wherein the sheath is provided with a cap.

17. A syringe as claimed in claim 1 wherein the housing is provided with a penetrable and self-closing cap to prevent fluid seepage.

18. A syringe as claimed in claim 1 wherein the needle axis is displaced from the centre line of the barrel.

19. A syringe as claimed in claim 1 wherein a detachable spacer capable of being labelled is located between the open end of the housing and the flanged end of the plunger so as to inhibit unwanted inward movement of the plunger.

20. A method of assembling a hypodermic syringe according to claim 1, including the steps of mounting a needle to the needle carrier, positioning the needle carrier in the housing such that the needle extends therefrom, and mounting a sheath to the needle carrier over the needle before positioning the needle carrier in the housing.

21. A syringe as claimed in claim 1, wherein the sealing means comprises an O-ring seal.

22. A syringe as claimed in claim 1, wherein the sealing means comprises engagement between the needle carrier and the housing.

23. A method of assembling a hypodermic syringe, comprising:

(a) mounting a needle to a needle carrier;

(b) positioning the needle carrier and needle through and in a housing such that the needle extends from the housing;

(c) forming a seal between the needle carrier and the housing during step (b); and

(d) mounting a sheath to the needle carrier over the needle before performing step (b).

24. A hypodermic syringe assembled according to the method of claim 23, wherein step (c) is effected by sealing means for defining the seal between the needle carrier and the housing.

25. A method of assembling a hypodermic syringe, comprising:

(a) mounting a needle to a needle carrier;

(b) mounting a sheath over said needle; and

(c) locating the needle carrier within a housing comprising first and second spaced apertures by inserting the needle carrier with the needle and the needle sheath mounted thereto through the first aperture and positioning the needle carrier such that the needle with the needle sheath thereon extends externally of the housing from said second aperture.

26. A hypodermic syringe assembled according to the method of claim 25 and further comprising sealing means for defining a seal between the needle carrier and the housing.