Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1991-09-06
1993-01-05
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604195, A61M 500
Patent
active
051766400
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a syringe provided with an engagement device able to cause the hypodermic needle to enter a cavity in the plunger shaft when the injection has been completed.
STATE OF THE ART
The problem of making a hypodermic syringe needle innocuous is currently important because of the serious problems of infection connected with accidental pricking with used and thus infected syringe needles. This problem which is exacerbated because many syringes designed for once-only use can in fact be used more than once.
Italian patent application No. 9543 A/88 of the present applicants describes a syringe in which, after use, the needle is made to enter a cavity in the plunger by means of a tension spring, one end of which is fixed to the inner surface of the plunger and which becomes operationally connected to a support member provided with a pawl able to engage the needle at the end of the plunger stroke and to pull it into said cavity.
Although effective, this device has certain constructional problems which make it difficult to implement in that the tension spring has to be fixed to the interior of the plunger, as stated.
SUMMARY OF THE INVENTION
The present invention enables a similar result to be obtained in a manner which considerably simplifies the construction and/or assembly of the syringe.
The syringe according to the present invention is formed from a cylindrical body, a plunger slidable within said cylindrical body and provided with a hollow shaft defining an inner chamber, and a hollow needle or metal cannula connected to said cylindrical body by first means which shear under a determined load, said syringe being characterised by comprising an engagement device which is connected to said plunger by second means which shear under a determined load at the end of travel of said plunger, and becomes operationally connected at the end of travel of the plunger to said needle and to a pneumatic actuator able to cause said needle to enter said chamber in the shaft of said plunger.
According to a preferred embodiment said pneumatic actuator is of the vacuum type, said plunger advantageously being provided with a hollow shaft defining an inner chamber in which vacuum is created and in which a piston rigid with said engagement device is slidable under sealed conditions.
With the proposed arrangement the syringe construction is simplified and its performance and reliability are optimized.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
DETAILED DESCRIPTION OF THE INVENTION
These and further advantages and innovative and operational characteristics of the present invention will be more apparent to the expert of the art with the aid of the accompanying FIGS. 1 to 5 which are given by way of non-limiting example, and of which:
FIG. 1 is a partly sectional view of the syringe according to the invention;
FIG. 2 is an axial section through the syringe during use;
FIG. 3 shows the syringe of FIG. 2 after use, with the needle retracted;
FIG. 4 shows the syringe of FIG. 2 during assembly; and
FIG. 5 shows a detail of the syringe of FIG. 2 in an enlarged scale.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIGS. 1 to 4 the reference numeral 10 indicates overall a hypodermic syringe constructed in accordance with the invention, and 11 indicates its cylindrical body, which is provided with a neck 12 and a guide ring 13.
The reference numeral 14 indicates a double-ended hollow needle 14 or metal cannula, provided with an engagement recess 15 and made rigid with the base 16 by a ring 18 or washer of a material which shears under a predetermined load; the
REFERENCES:
patent: 4772265 (1988-09-01), Walter
patent: 5049133 (1991-09-01), Pascual
Nacci Gaetano
Nacci Tagliaferri Carla
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