Injection device

Details Injection device Injection device

1993-10-13

1994-12-06

Yasko, John D.

Surgery

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

Treating material introduced into or removed from body...

604232, A61M 500

Patent

active

053706293

DESCRIPTION:

BRIEF SUMMARY
The invention concerns an injection device defined in the preamble of claim 1.
An injection device of this kind (hereafter frequently shortened to "device") is known from WO 87/02895.
The known injection device is used to inject specific, selected quantities of liquid from a plunger-fitted ampoule. It comprises a manually actuated system including an output member preferably in the form of flanged rod displaceable in the direction of plunger advance and an operational head which can be moved both axially and rotationally. A drive element displaceably supporting the output member can be moved along the plunger advance from a rest position into an end position and back into the rest position. When the drive element is in its rest position, the output member, then a distance from the plunger, can be displaced in the direction of advance over a path corresponding to the plunger stroke required for the particular quantity of liquid to be injected without impacting the plunger. The plunger stroke is determined by the rotation of the operational head. A detent mechanism emitting a slight acoustic signal when passing each detent allows the patient to count these signals and thus to ascertain the magnitude of the new injection dose. While the drive element is advanced from the rest position into the end position, the output member impacts the plunger which it then displaces along the pre-selected plunger stroke. A spring keeps the drive element in its rest position and loads it when it is moved into the end position.
In practical application, this injector is not entirely satisfactory for the following reasons.
The dimensions of the injector are approximately those of a fountain pen because it must be worn constantly by the patients who may need an injection at any time. However, the relation between the length of the actuation system and the maximum injected dose of this known injector falls short because the maximum injection dose supplied by this injector is insufficient for some patients. On the other hand, ampoule size and concentrations of the injection solutions in use have long been set and changing them would meet with much resistance from drug makers. Accordingly, an injector of the given total length is desired which would allow injection of larger maximum doses.
Accordingly, an object of the invention is to create an injection device of approximately the same size as the known injector but permitting administrating of larger injection doses.
This object is achieved by the features of the characterizing part of claim 1; the further claims relate to advantageous embodiments.
The invention is illustrated in the drawings.
FIG. 1 is a longitudinal section of an injector of the state of the art,
FIG. 2 is a longitudinal section of the injection device of the invention,
FIG. 3 is the cross-section A--A of the device of FIG. 2,
FIG. 4 is the cross-section B--B of the device of FIG. 2,
FIG. 5 is the cross-section C--C of the device of FIG. 2, and
FIG. 6 is a geometric development along the direction D--D of FIG. 2.
The same parts are denoted by the same references in the drawings.
A known injector 1 as shown in FIG. 1 (and in FIGS. 1 through 7 of WO 87/02895) is described in detail in the following. At its front part 2 it comprises a replaceable ampoule 4 with a plunger 5 to drive the substance to be injected through an injection needle 6. At its rear portion 3 it includes a manually operated, tubular actuation system 7 fitted with an operating head 8, an output member preferably in the form of a rod 9 with a flange 19, a guide element 24 and a drive element 11.
While evincing an overall circular cross-section, the rod 9 has planar surfaces at both sides and is threaded on the circular parts. It is seated by this thread in an internal thread 27 of drive element 11 which is non-rotatably affixed to injector 1. Together with the entire actuation system 7, the drive element 11 can be moved against the force of a spring 16 from a rest position into an end position by axially driving operating head 8 and transmitting

REFERENCES:
patent: 4973318 (1990-11-01), Holm et al.
patent: 5017190 (1991-05-01), Simon et al.
patent: 5292318 (1994-03-01), Haber et al.
patent: 5295976 (1994-03-01), Harris
patent: 5304152 (1994-04-01), Sams

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