Injection devices

Details Injection devices Injection devices

1998-12-18

2000-06-20

Polutta, Mark O.

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

604135, 604192, 604220, 604244, A61M 520, A61M 532, A61M 5315, A61M 500

Patent

active

060772476

DESCRIPTION:

BRIEF SUMMARY
This invention relates to injection devices and is particularly but not exclusively concerned with those for capsules where two ingredients are initially separated, but which are mixed immediately prior to injection. These are well known, and will not be described in detail. But a typical arrangement is to have liquid in a rear chamber of the capsule and powder in a forward chamber, the two being connected by a narrow bypass passage. The first stage is to compress the liquid so it forces its way through the bypass gradually to infiltrate and mix with the powder. Then, in the second stage, the plunger is urged forwards and the mixture is injected through the needle at the leading end.
It is the aim of this invention to have a device that will accept such a capsule, with its needle, and operate it, at the same time being of simple construction, with as few parts as possible so that it can be a throwaway item.
According to the present invention there is provided an injector device comprising a two-part barrel, the parts being mutually telescoped and containing spring means to act in a forward direction on a capsule housed therein, the forward part providing a passage at its leading end through which a needle at the leading end of the capsule can be projected, wherein for operation the parts of the barrel have their telescopic overlap increased, which exposes for operation a trigger that holds the capsule in a needle retracted position, actuation of the trigger then releasing the capsule for that to be urged forwardly by the spring means to project the needle.
The spring means may also be arranged, after urging the capsule forwards, to have residual energy to act on the contents of the capsule to eject a dose through the needle.
Conveniently, the forward part of the barrel telescopes into the rearward part.
Preferably the trigger is integrally formed with the part that telescopes into the other one. Generally there will be detents to prevent the parts being detelescoped from either position.
The spring means will conveniently be a coil spring acting between the rear end of the rearward barrel part and the rear end of the capsule.
When the capsule contains two separate components, with a plunger at the rear end of the capsule acted upon by the spring means, the increase in telescopic overlap is conveniently arranged to cause the spring means to be compressed and subsequently re-expand to press the plunger forwards and thereby force one component in the capsule to mix with the other component. The travel of the plunger within the capsule during the mixing operation will preferably be less than the mutual movement of the two barrel parts when the overlap is increased, whereby the spring means will have residual energy after the components have been mixed, first, when the trigger is activated, to shoot the capsule forwards to a limit, acting on the plunger, this projecting the needle, and then to press the plunger further into the capsule and thereby eject a dose through the needle.
With a double-ended needle there can be a lost motion connection between means carrying the needle and the capsule which is taken up during the forward movement of the capsule, causing the rear end of the needle to pierce a membrane defining the forward end of a dose chamber of the capsule.
For a better understanding of the invention one embodiment will now be described, by way of example, with reference to the accompanying drawings, in which:
FIGS. 1-5 are axial sections of an injection device in progressive stages of operation,
FIG. 6 is a perspective view of the injection device prior to use, and
FIG. 7 is a perspective view of the injection device almost ready for use.
The injection device is a two part barrel which contains a capsule 1 with a needle 2 at its leading end. This will have a two component dose which will be mixed and injected during the course of operation. It can be of known type and will not be described in detail.
The rear part 3 of the barrel is of stepped cylindrical form having a closed rear end 4 and a shoulder

REFERENCES:
patent: 5358489 (1994-10-01), Wyrick
patent: 5527287 (1996-06-01), Miskinyar

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