Dispensing – With discharge assistant – Motor operated
Patent
1996-03-27
1998-01-06
Shaver, Kevin P.
Dispensing
With discharge assistant
Motor operated
604141, 604145, 417379, 417395, A61M 3700
Patent
active
057045208
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to liquid material dispensers, and a valve particularly suitable for use in such dispensers, and more particularly to dispensers for dispensing medicaments at small, precisely controlled rates.
BACKGROUND ART
The invention is especially useful where the liquid is driven from the dispenser by the force of gas generated at a suitable rate by an electrolytic cell. Examples of such systems are described in U.S. Pat. Nos. 5,062,834 and 5,090,963, and in our International Patent Publication WO 93/23096, which are incorporated by reference in their entirety for all purposes as if fully set forth herein.
In a variety of applications, including, but not limited to, drug delivery systems, it is required to dispense or deliver a liquid at a predetermined, precisely controlled rate. Electrolytic pumps, such as those described in the above-mentioned U.S. Patents, have been developed for this purpose. These pumps, however, generally include relatively large pumping chambers, and hence their pumping rates may be significantly influenced by pressure and temperature changes, particularly when the dispenser is used over long periods of time and/or under varying ambient conditions.
The electrolytic pump described in our International Patent Publication WO 93/23096 provides a liquid material dispenser or pump of a construction which can include a pumping chamber of relatively small volume so that the rate of delivery of the liquid is less sensitive to pressure and temperature variations.
However, the venting of the pressure control chamber is carried out through a slow acting vent which releases the gas from the pressure control chamber to the atmosphere to thereby drive the pumping member through the return stroke and draw liquid from the reservoir into the pumping chamber. Such a slow vent may at times become plugged, reducing the venting rate or interrupting it entirely. In addition, since the venting is carried out continuously at all times, it tends to reduce the efficiency of the pumping stroke by robbing the pumping chamber of some of its relatively high pressure gases when it is desired that those gases exert maximum force on the diaphragm to pump the liquid.
In addition, the device disclosed in our International Patent Publication WO 93/23096 uses a pair of one-way umbrella valves for controlling the flow of liquid from the reservoir to the outside of the device.
Furthermore, the device described in our International Patent Publication WO 93/23096 is designed so that gas production continues for a pre-determined period of time. The duration is selected so as to deliver the desired amount of liquid through the outlet. However, for a variety of reasons, including, but not limited to, partial plugging of the outlet or temperature and pressure variations, the amount of liquid delivered during a fixed period of time may vary.
There is thus a widely recognized need for, and it would be highly advantageous to have, an electrolytic pump along the lines described in our International Patent Publication WO 93/23096 but which would feature means for more efficiently venting the pressure control chamber and which would make use of more one-way valves, and which would have the ability to automatically discontinue the delivery of liquid when a fixed amount of liquid has been made to pass through the outlet.
DISCLOSURE OF INVENTION
According to the present invention there is provided a liquid material dispenser, comprising: (a) a housing including a reservoir for storing liquid to be dispensed, an outlet through which the liquid is dispensed, and a connecting passageway between said reservoir and said outlet; (b) a reciprocatable pumping member located in said passageway, one side of said pumping member defining a pumping chamber with said passageway, and the other side of said pumping member defining a pressure control chamber, said pumping member being cyclically displaceable through a pumping stroke for pumping liquid through said outlet and a drawing stroke for drawing liquid
REFERENCES:
patent: 4350477 (1982-09-01), Mazal
patent: 4687423 (1987-08-01), Maget et al.
patent: 5062834 (1991-11-01), Gross et al.
patent: 5090963 (1992-02-01), Gross et al.
patent: 5242406 (1993-09-01), Gross et al.
patent: 5246147 (1993-09-01), Gross
Elan Medical Technologies Limited
Maher Kathleen L.
Shaver Kevin P.
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