JPH0490766A - Subcutaneous injector having retractable needle - Google Patents

Abstract

PURPOSE: To facilitate a lock mechanism by locking a hub by a shaft extending from the bottom of a plunger and an enlarged hole formed in the bottom of the shaft. CONSTITUTION: An injector is provided with a hollow external cylinder 10 whose both ends are opened, and the upper end is provided with a finger flange 12, and the bottom end is provided with a lip 11 extending inward. A hard plastic and rigid needle carrier 20 is tightly sealed inside the external cylinder by the lip 11, and a projection extending outward of the external cylinder 10 is fitted to a standard subcutaneous injection needle or a cannula 90. A single seal is thus provided by friction between the external wall of the needle carrier 20 plus the external cylinder 10 and the inner wall of the lip. A plunger 50 is slidably attached to the external cylinder inside for positioning a liquid chamber 100 and a shaft 80 is extended from the bottom 52 of the plunger 50 with a terminal. The hub is so constituted as to be fitted to a hub 81 in an enlarged hole in the adjacent to the top end of the carrier 50 and be locked therein. The plunger 50 is well fitted around the circumference of the shaft 80 between the end 52 of the plunger and the hub 81. The hub 81 is click-locked after the use and locked in a carrier so as to retreat the carrier 20 and the needle 90 in the external cylinder.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

This patent application is a continuation-in-part of patent application no. 07/322,282 filed by the applicant on March 13, 1989. [0002]

BACKGROUND OF THE INVENTION Due to the recent AIDS virus, which can be transmitted by contaminated hypodermic syringes, several retractable needle hypodermic syringes have been invented and patented. Retracting the needle into the syringe barrel after use is known as "needle stick," i.e.
This reduces the risk of the needle accidentally sticking into the person receiving the injection after using the syringe. A recently patented syringe with a retractable needle includes US Pat. No. 4.692.156 (Haller).
r) ) No. 4.675.005 (De
Luccia) ) 4th. '/41.830 issue (
No. 4,790,822 of the present applicant. Although each of these patents discloses patents suitable for use, none appear to be simple enough structures to be mass-produced at competitive cost. Collectively, the patents disclose complex locking or locking mechanisms for locking the needle carrier to the plunger or sealing the carrier within the barrel. [0002] Taking into account the practical circumstances that hypodermic syringes are disposable and are used only once, the applicant has proposed a simple type that can be manufactured at low cost and is fully functional. Developed a syringe. [0003]

[Means to solve the problem]

The hypodermic syringe with retractable syringe of simple construction of the present invention is intended to have a minimum number of parts and utilize as much as possible of currently available syringe parts. The syringe is open at both ends, has a finger flange at the upper end, and extends inwardly at the lower end for attachment to a standard hypodermic needle or cannula (the terms are used interchangeably herein). The only seal is provided by friction between the outer wall of the needle carrier and the inner wall of the barrel and lip. A plunger is slidably mounted within a barrel defining a fluid chamber. A shaft extends from the lower end of the plunger which terminates in the hub. The hub is adapted to fit into an enlarged hole near the top of the carrier and to be lockable. The plunger fits snugly around the shaft between the end of the plunger and the hub. The hub snaps and locks into the carrier after use, allowing the carrier and needle to be retracted into the barrel. Furthermore,
The hub can be broken within the carrier to block the fluid path and prevent further use of the syringe. [0004] The friction seal between the carrier and the barrel provides a sufficient sealing effect for at least one use in which the barrel loses its proper condition after a number of movements within the barrel. The present invention differs from the prior art in that the locking mechanism is of simple construction and there is a special sealing mechanism for the carrier. [0005]

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which like parts are designated by like reference numerals. [0006] FIG. 1 shows a hypodermic syringe having a retractable needle of the present invention with all components including an inwardly extending lip 12 at the other end.
have. The syringe has a standard finger flange 1 at one end.
2 and is shown with a hollow cylindrical outer tube 10 having an inwardly extending lip 11 at the other end. A rigid needle carrier 20 made of hard plastic is inserted into the barrel 10 through a hole in the flanged end, and the lip 1
1, and the extension portion 24 extends outward from the outer cylinder 10. A cannula 90 is attached to the extension 24 by a friction fit through a sleeve 30 integral with the cannula 90. The cannula 90 is provided with a protective sheath 40 for protection before use. A plunger 50 having a shaft 80 around which a rubber seal 60 is secured is inserted into the barrel 10 and the syringe is ready for use. Thus, the entire syringe consists of only six separate parts. The carrier and plunger differ only from those in a standard syringe by removing the needle attachment extension from the lower end of the barrel to provide lip 11. In conventional syringe-based embodiments, even the plunger seal is reused. [0007] Referring now to FIG. 2, a novel component is illustrated. A carrier 20 is seated on the lip 11 with an extension 24 extending outwardly from the barrel. The outer diameter of the carrier is sized to provide a tight friction seal with the inner wall of the outer cylinder 10. The inner wall of the outer cylinder 10 and the outer diameter of the carrier 20 are relatively smooth for ease of manufacture. In the case of structures of different materials, the gap must be adjusted so that the carrier can be retracted with minimal force, while providing a seal. Sleeve 30, integral with cannula 90, is secured to extension 24, typically by a tight friction fit. However, additional fastening means such as commonly used adhesives may also be used. A central bore 21 extends through carrier 20 and provides fluid communication between cannula 90 and fluid chamber 100. A hollow chamber 22 having an enlarged hole 23 is provided near the upper end of the central hole 21 . [0008] Plunger 50 is slidably mounted within outer cylinder 10. A shaft 80 extends from the lower end 52 of the plunger 50. At the lower end of the shaft 80 is a hub 81 which is adapted to align within the enlarged hole 23 of the carrier 20 and be knit-locked. Wide shoulders 82 and 83 are provided along shaft 80 and secure rubber seal 60 to the shaft between plunger end 52 and hub 81 . [0009] Referring to FIG. 3, cannula 90 is illustrated retracted into barrel 10. The hub is engaged within the enlarged bore and the shoulder portion 84 is in locking engagement with the upper inner surface 25 of the enlarged bore 23. The shaft 80 is shearable above the hub 81 so that the hub can fail within the enlarged hole 23 and effectively block the fluid passageway 21. A preformed perforated portion (not shown) may be provided to allow shearing while providing sufficient pulling force to draw the cannulated carrier into the barrel. [0010] During use, plunger 50 is pressurized within barrel 10, creating a positive resistance force between hub 21 and carrier 20, as shown in FIG. Fluid can then be aspirated into chamber 100 by inserting cannula 90 into the fluid for injection and retracting plunger 50. Air drawn into the fluid can be removed by inverting the syringe and tapping it.
The bubble will rise to the end of the cannula and can be removed by the usual method of pressurizing a plunger to force fluid out of the cannula. Fluid can then be injected. Immediately after the nulla is removed from the patient, further pressure is applied to the plunger so that the hub 81 engages the carrier 20. After hub 81 engages carrier 20, needle carrier 20 with cannula 90 is retracted into barrel 10. Finally, hub 81 is broken and separated from shaft 80, and carrier 20 prevents further use of the syringe. [0011] All materials of the structure are conventional. for example,
The barrel can be made of transparent hard or soft plastics currently commonly used in disposable syringes. The plunger and needle carrier are made of hard plastic and the plunger seal is made of standard rubber suitable for medical purposes. [0012] If the barrel is made of a soft, deformable type of plastic, the needle carrier may be used as disclosed in commonly-owned U.S. Pat. No. 4,790,822, incorporated herein by reference. It is desirable to provide a stopper or a shoulder portion at the top of the holder. Referring to FIG. 4, the hub 81 and shaft 80 with enlarged hole 23 disclosed herein is used in place of the T-head and frusto-conical snap ring disclosed in the applicant's previous patent. has been done. A shoulder or stop 10.10b extends inwardly from the wall directly above the carrier 20 and provides additional securing means to the carrier. Plunger 50 is provided with expansion means as disclosed in Applicant's previous patents to deform the wall and allow retraction of carrier 20 when hub 80 engages enlarged hole 23. [0013] Further, as shown in FIG. 5, the positions of the shaft 80a and the enlarged hole may be reversed, with the central hole 21 of the carrier 20 extending through the shaft 80a. As shown in FIG. 6, the shaft 80a
longitudinal throwers) 90a to 90d;
It provides some flexibility to the hub 81 so that the hub 81 is easily locked into the locking hole 23 in the lower end of the piston 50. When the shaft 80 is at the lower end of the piston, as shown in FIG.
90a-90d similarly provide flexibility to hub 81. Such flexibility allows the hub 80 or 80a to
When entering the central hole, it is indented inward, and then the enlarged hole 23
Upon entry, it expands elastically outward to allow locking engagement by shoulders 84 or 84a.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing all parts of the retractable needle syringe of the present invention. FIG. 2 is a partially sectional side view of the lower end of the assembled syringe of the present invention.

FIG. 3 is a side view, partially in section, of the lower end of the assembled syringe with the needle retracted and the hub broken; FIG.

FIG. 4 is a partially sectional side view of the lower end of the second embodiment of the syringe of the present invention.

FIG. 5 is a partially sectional side view of the lower end of the third embodiment of the syringe of the present invention.

FIG. 6 is a perspective view, partially in section, of another hub that may be used with all embodiments of the invention.

[Explanation of symbols]

10 Outer cylinder 11 Lip 12 Finger flange 20 Needle carrier 21 Center hole 24 Extension part 30 Sleeve 50 Plunger 60 Rubber seal 80 axes 81 Hub 84 Shoulder part

[Figure 1]

[Figure 2]

[Figure 3]

[Figure 4]

[Figure 5]

Claims (8)

[Claims] Claim 1: A hypodermic syringe having a retractable needle,
a hollow cylindrical barrel of semi-rigid deformable plastic open at both ends, having an inwardly extending lip at the lower end and a finger flange at the upper end; a rigid cylindrical needle carrier seated thereon and held in place by a friction-sealing engagement between the outer diameter of the carrier and the inner wall of the barrel, the needle carrier extending through a hole in the lower end of the barrel; the needle carrier having an extension; an inner shoulder extending inwardly on the inner wall of the barrel directly above the carrier to assist in holding the carrier in place during use; a hypodermic needle attached to the carrier; a plunger slidably mounted within the barrel through an open top end and defining a fluid chamber between the carrier and the plunger; a central hole in fluid communication between the needle and the chamber through an extension; an enlarged hole formed in the carrier near the chamber and coaxial with the central hole; and an axis extending from a lower end of the plunger. a hub formed on the lower end of the shaft and capable of being locked within the enlarged hole; and a hub provided on the plunger for deforming the shoulder portion when the hub engages the enlarged hole; and expansion means for releasing the carrier. Claim 2: The hypodermic syringe of claim 1,
The shaft is shearable above the hub, and after use,
A hypodermic syringe, characterized in that the hub can be broken and left in the hole. 3. The hypodermic syringe of claim 1 further comprising a plunger seal member secured about the shaft between the plunger and the hub. 4. The hypodermic syringe of claim 3 further comprising at least one shoulder formed about said shaft to retain said seal about said shaft. 5. The hypodermic syringe of claim 1, wherein said shaft is hollow and is provided with a longitudinal slot along its outer periphery, said hub recessing inwardly upon entering the central hole, and said hub recessed inwardly upon entering said enlarged hole. A hypodermic syringe, wherein the syringe expands upon entering the aperture to lockably engage the enlarged aperture. 6. A hypodermic syringe having a retractable needle,
a hollow cylindrical barrel open at both ends, having an inwardly extending lip at the lower end and a finger flange at the upper end; a rigid cylindrical needle carrier held in place by a friction-sealing engagement of the diameter and an inner wall of the barrel, the needle carrier having an extension extending through a hole in the lower end of the barrel; a hypodermic needle attached to the extension; a plunger slidably mounted within the barrel through an open top end and defining a fluid chamber between the carrier and the plunger; an enlarged hole formed in the lower end of the plunger near the chamber; a shaft extending from the upper end of the carrier; and a central hole providing fluid communication between the needle and the chamber through the carrier, extension, and shaft. a hub at the lower end of the shaft adapted to be locked within the enlarged hole. 7. The hypodermic syringe of claim 6, wherein the shaft comprises:
A hypodermic syringe, characterized in that a longitudinal slot is provided along its outer periphery to provide flexibility to said hub and permit said hub to be locked into said enlarged hole. 8. The hypodermic syringe of claim 7, wherein the barrel is comprised of semi-rigid deformable plastic, and the barrel extends inwardly over an inner wall of the barrel directly above the carrier. an internal shoulder on the plunger that extends and assists in holding the carrier in place during use; when the hub engages the enlarged hole, the shoulder deforms and the carrier and a release expansion means.