Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1997-01-15
1998-11-24
Mendez, Manuel
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
A61M 530
Patent
active
058400613
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an ejection apparatus for the high-pressure ejection of a liquid or a solid particle-containing-liquid. The ejection apparatus has a pressure chamber for accommodating the liquid. The chamber opens into an ejection opening, and is delimited by a working piston which can be displaced in the chamber by a drive.
In known needle-less inoculation devices, the driving piston is in most cases actuated by a tensioned spring, wherein the driving piston acts upon the liquid with a relatively high pressure and the complete liquid volume present in the pressure chamber is ejected through the ejection opening. It is also known (See for example, GB Patent Specification No. 993 309) that the pressure chamber is formed as an ampoule having deformable walls, wherein a driving piston is used as a drive and to first impart an impact impulse to the working piston, in order to obtain a higher initial ejection pressure and to achieve penetration through the skin, whereafter the working piston is further pushed by a spring arrangement in order to push the rest of the liquid volume out of the ampoule.
The liquid volume generally relates to relatively large quantities in the range of cubic centimeters, which can result in trauma to the tissue surrounding the inoculation location. On the other hand, there is a need for injecting small quantities of liquid in particular cases. Namely, it has been determined that, with a high pressure injection of small quantities of colorants into tissue, the colorant was homogeneously distributed with distinctly less damage to the tissue.
SUMMARY OF THE INVENTION
The present invention solves the problem of how to design an ejection apparatus of the above mentioned type so that small quantities of liquid, in particular cases cubic millimeters, can also be ejected.
According to the invention, this is achieved in that the drive is formed as an impact member exerting an elastic impact on the working piston, which impact member can be accelerated and driven until it elastically impacts the end of the working piston facing away from the pressure chamber, wherein the impact member is not driven with the elastic impact, and the volume of the pressure chamber is larger than the volume of the liquid displaced by the working piston during its working stroke.
As a result of the impact member striking the working piston, an elastic impact is transmitted to the working piston, whereby the working piston transmits a high pressure impulse to the liquid in the pressure chamber which results in high pressure ejection of the liquid from the ejection opening. The ejection pressure and also the ejected liquid volume depend on the impact velocity of the impact member striking the working piston, and can therefore be adjusted by adjusting the driving velocity of the impact member. Since the driving member looses its driving force as a consequence of the elastic impact, only a short impulse is transmitted to the liquid. By means of the short, high pressure impulse transmitted to the liquid in the pressure chamber, a corresponding small quantity of the liquid is ejected from the ejection opening without the total volume of the pressure chamber being emptied. In contrast to the prior art, the impact transmission is only used to eject this small quantity without subsequently ejecting the total volume of the pressure chamber. This is achieved by means of the impact member exerting an elastic impact on the working piston and by the impact transmission, that is due to the transmission of the impulse, the impact member is no longer driven and does not exert any further driving force on the working piston. As a result, it is possible to eject only a small quantity of the liquid in doses.
The volume of the pressure chamber is substantially larger than the displacement volume of the working piston in order to be able eject a small, but dosed quantity of the liquid, independently of the size of the pressure chamber. Preferably, the ratio between the volume of the pressure cham
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Klopfenstein Denis
Menne Andreas
Merkle Wolfgang
Schulz Manfred
Ferton Holding
Mendez Manuel
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