1. Field of the invention
The present invention is related to a safe retractable type syringe; and especially to an engaging structure of a barrel and a needle set retractable into the barrel, wherein the needle set is inserted into and connected with the inner wall of the barrel from the front end of the barrel, and is pulled back into the barrel to be connected with the barrel after injection. The needle set and the barrel are suitably connected, production and controlling are easy, the product of such syringe is convenient, and the operation of inserting as well as pulling back the needle set are easy too.
2. Description of the Prior Art
The U.S. Pat. No. 5,899,887,owned by the same patentee as the present invention, discloses a safe retractable type syringe structure having a changeable needle, referring to
And the U.S. Pat. No. 5,217,437 also discloses a needle protecting device, wherein an inner surface of a needle shield 40 is also provided with a plurality of detents 50 able to be received within slots 26 in the triangular protrusions 24 to releasably retain the needle shield 40 in its retracted position (lines 8-13, column 6). And thereby, the needle shield 40 can be moved frontward to cover the needle. However the mode of connecting of the needle shield 40 of such syringe with the needle must be specifically designed; and manufacturers must have their cost of producing such needle shields 40 increased.
In making engaging of a needle seat with a barrel of the present invention, the engaging structure of a needle set and the inner wall of the barrel “A” of a safe retractable type syringe of the present invention must be taken into consideration carefully. In the above U.S. Pat. No. 5,899,887, the engaging of the needle seat with the inner wall of the barrel is unable to be applied to the present invention, because by such mode of engaging, sometimes the needle set is hard to be inserted to engage in the barrel from the front end of the latter, sometimes the needle set is overly loose after it is inserted into the front end of the barrel, if the problem of tolerance in manufacturing is not well controlled; for example, when the outer diameter of the needle set and the inner diameter on the front end of the barrel are not suitably controlled, or the sizes and the positions of the plural flanges on the inner wall of the barrel (there are three flanges disclosed in
An explanation has to be presented: for a conventional non-retractable type syringe, its needle seat is inserted from the front end of its barrel, this is that the conventional non-retractable type syringe needs no consideration on the problem of pulling the needle set back into the barrel, it needs only to have its needle set inserted and tightly connected. While the main point of the present invention is resided in that: the needle set is directly inserted from the front end of the barrel and is retractable, the structure disclosed in the present invention is suitable for production, quality control and manipulation.
The motive of the present invention is to improve the engagement of the needle set with the barrel, wherein the needle set is directly inserted from the front end of the barrel, the needle set and the barrel are tightly engaged with each other, thereby liquid medicine can be sealed. The operations to insert with a force and connect the needle set into the barrel and to pull the needle set into the barrel are both easy. The engaging structure of the needle set with the barrel is benefit to manufacturing of the present invention.
The primary object of the present invention is to provide a safe retractable type syringe; wherein an engaging structure of a needle set and a barrel is improved, the needle set thus can be inserted into and connected with the barrel from the front end of the latter, thereby the product of the present invention is easy for manufacturing, operating and use, and in which liquid medicine is sealed.
The secondary object of the present invention is to provide an engaging structure of the needle set and the barrel for a safe retractable type syringe, the structure is applicable to a safe retractable type syringe either with a standard needle set having a changeable needle or with a needle set having an unchangeable needle.
To achieve the above objects, the present invention is comprised of a needle set, a barrel and a plunger. Wherein the front end of the needle set is connected with a needle, while the rear end is provided with a first engaging portion, the bottom of the needle set is provided on the periphery thereof at least with a first annular flange; the barrel is a hollow pipe, its front end is a socket for connecting thereto of the needle set, the socket is provided on the inner wall thereof with a second annular flange and at least with two protruding ribs equidistantly away from the second annular flange. The rear end of the barrel is used for slipping in the plunger of which the front end is provided with a piston, a second engaging portion is provided on the front end of the piston. Thereby, when the needle set is connected into the needle-set socket from above, the first annular flange provided on the periphery of the needle set is located between the second annular flange provided on the inner wall of the needle-set socket and the two protruding ribs, in order to overcome the problem of tolerance in manufacturing to make easier for manufacturing, assembling and use as well as to increase the effect of sealing liquid medicine. When the front end of the plunger is pushed to the topmost position, the first engaging portion and the second engaging portion connect with each other, so that when the plunger is pulled back, the needle set is pulled back into the barrel.
The present invention will be apparent in its features after reading the detailed description of the preferred embodiments thereof in reference to the accompanying drawings.
a is an exploded perspective view showing the upper end portion of the first embodiment of the present invention;
b is a sectional view taken from a section line AA in
a is an enlarged sectional view taken from
a is a partial sectional schematic perspective view of the embodiment of
Referring to
The retractable type needle set 2 includes a needle seat 21 and a needle 22, the rear end of the needle seat 21 is provided with a first engaging portion 212; the external diameter of the needle seat 21 is coincident with the inner diameter of the needle-set socket 11, so that the needle seat 21 can be connected with the latter, and the way of connection is that the needle seat 21 is inserted into the barrel 1 from the front end of the needle-set socket 11 of the barrel 1; the external wall of the middle section of the needle seat 21 is provided at least with a first annular flange 211 to increase the sealing function in connecting. In this embodiment, the first engaging portion 212 is an engaging portion with a recess, while the recess is formed from more than one detent piece.
The plunger 3 is generally a pusher rod 31, the front end thereof has a piston 32; a second engaging portion 33 is provided on the front end of the piston 32. In this embodiment, the second engaging portion 33 is a protruding hook portion. The plunger 3 is provided for slipping into the barrel 1 to move forward and backward therein.
Referring to
Referring to
The standard needle set 4 is inserted into the needle-set socket 11 provided on the front end of the barrel 1. The first flange 434 of the bottom seat 43 is engaged between the second flange 111 of the needle-set socket 11 and the three protruding ribs 112, so that the syringe will be sealed during the processes of medicine drawing out and injection. When the front end of the plunger 3 is pushed to the topmost position after injection, the second engaging portion 33 on the front end of the piston 32 is connect with the first engaging portion 435 of the bottom seat 43 to pull the plunger 3 rearwardly, and the standard needle set 4 can then be pulled into the barrel 1.
The above stated in referring to the drawings are preferred embodiments of the present invention, for example, wherein the first engaging portion 212 of the needle seat 21 on the retractable type needle set 2 and the first engaging portion 435 of the bottom seat 43 of the standard needle set 4 are both provided with recesses; while the second engaging portion 33 on the plunger 3 is provided with a protruding hook portion. However, in practicing, other shapes and structures able to get the function of engagement can alternatively be adopted. By all means, the first engaging portion 212, 435 respectively of the needle seat 21 of the retractable type needle set 2 and the bottom seat 43 can be provided with hook portions, while the second engaging portion 33 on the plunger 3 can be provided with a recess, and the same function of engagement can likely be achieved.
In operation, when the needle of the syringe is inserted into the skin surface of a man, normally an impeding force is induced against injection, the impeding force will make contracting of muscle in different degrees according to the degrees of nervousness of the person being injected, and normally the value of the impeding force is about 0.6 kg, but sometimes the muscle becomes stiff because of nervousness of the person, the value probably reaches 1.0 kg, or even higher. Thereby in practicing, referring to
Accordingly, the present invention has the following advantages:
As stated in the above disclosed, the present invention can surely attain its expected objects to provide an improved engaging structure of a retractable type needle set and a barrel, the structure undoubtedly has its practical value of utility.
It will be apparent to those skilled in this art that various modifications or changes made to the elements of the present invention without departing from the spirit of this invention shall fall within the scope of the appended claims.
This is a continuation-in-part application of the applicant's U.S. patent application Ser. No. 10/418,062 filed on Apr. 18, 2003.
Number | Date | Country | |
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Parent | 10418062 | Apr 2003 | US |
Child | 11128258 | May 2005 | US |