Dispensing – With discharge assistant – With movable nozzle interconnected therewith
Reexamination Certificate
1999-09-02
2001-06-26
Shaver, Kevin (Department: 3754)
Dispensing
With discharge assistant
With movable nozzle interconnected therewith
C222S380000
Reexamination Certificate
active
06250509
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a dispenser with which flowable media may be released or discharged by pressurizing. Particulary liquid media, but also pasty, powdery and/or gaseous media are suitable. The dispenser is held and actuated single-handedly. The dispenser is primarily made by injection molding or of plastics. The medium may be discharged atomized, or delivered in discrete clusters or droplets having a volume of at least 5 or 15 &mgr;l and at the most 40 or 25 &mgr;l. The medium contains medicinal active substances for eye treatment, or the like.
Dispensers need to be microbiologically sealed to prevent the medium stored therein from being contaminated by germs gaining access from without. The medium needs to be protected from such detrimental effects during a long shelf life not only prior to first-time use (priming) of the dispenser but also after the initial or any following medium discharge. The dispenser may be for a single discharge of a medium dose in which its actuator is moved in one direction only up to the dispenser being totally emptied with no return or suction stroke being necessary. The total supply of the medium may be contained in a single delivery chamber, without any additional medium reservoir. The volume in the chamber is then variable for pressurized delivery of the medium. The dispenser or its actuator may also operate in two opposite direction via a working stroke for pressurized delivery directly followed by a return stroke for sucking a further medium dose into the delivery chamber. After discharge of a medium dose the microbiological seal is always able to be reproduced until the next discharge, which is not always necessary in the case of a disposable dispenser.
For this seal either a single valve or several valves may be suitable. The valves closing gaps are located in sequence in the flow direction in the outlet duct. The last or downstream valve is located as near as possible to the medium outlet or its opening bounds as formed by the transition between an inner circumference and an end face transversely adjoining this circumference. At this transition the medium detaches from all inner circumferences or internal dispenser faces for release to the environment. The medium may then still be guided downstream of the transition by accessible external dispenses faces.
OBJECTS OF THE INVENTION
An object is to provide a dispenser which avoids the drawbacks of known configurations and achieves advantageous effects of the aforementioned kind. Another object is to ensure a repeated microbiological seal against ingress of germs trough the bounds of the medium outlet or of inflow openings. A still further object is to provide for simple handling or for uncomplicated construction. An object is also to provide the dispenser for modular composition permitting adaptation to media differing in flowability.
SUMMARY OF THE INVENTION
The dispenser has a valve closing with high areal pressure. The valves closing gap may also form the cited bounds of the medium outlet. Thus the closing gap extends up to the outA ermost possible location of the outlet duct where the medium emerges on discharge as described. This location is a microbiological seal when the valve is closed. Thus, at the most, germs are able to collect on the permanently freely accessible outside of the dispenser but not gain access upstream past the tight closing gap to internal faces of the dispenser.
The closing force is not reduced until the medium pressure in the outlet duet has attained at least 0.7 or 1 or 1.4 bar. The valve could be opened by purely mechanical actuation independently of the medium pressure. The cited sealing effect and preventing germ ingress with the valve open may also be improved by keeping valve travel as small as possible. The maximum relative travel of the two valve elements for opening or closing is less than 2 mm, 1 mm, 0.7 mm or 0.4 mm, e.g. 0.3 mm. On droplet discharge the medium then emerges practically with zero pressure or in a capillary creeping action through the valve gap. Upstream thereof it is the cited higher pressure of the medium that maintains the valve open. Thus the emerging and the opening medium fractions communicate within the outlet duct. Further upstream, means such as a pump for generating a medium pressure higher than the aforementioned pressures, i.e. two to five times higher may be provided, the medium pressure amounting to e.g. at least 4, 6 or 7 bar.
With this pressure the valve may be kept open. When a pressure substantially lower as compared thereto is generated in the conveying chamber, for instance maximally or less than two or one bar, then for opening the final valve it is of advantage to provide means for transforming the force by a transmission ratio between the conveying chamber and the control member which opens the final valve. Therefor the opening pressure acts on correspondingly large faces areas of the control member. Compared thereto the faces on which the medium pressure acts in the closing direction are substantially smaller.
To nevertheless attain a discharge of the medium at the medium outlet at a pressure which as compared to the above is reduced or pressureless, a throttling gap is provided down-stream of the medium fractions which open the valve. The passage cross-section of the throttling gap is substantially smaller than that of the opened valve and may be varied as a function of the medium pressure. For example, the opened passage cross-section of the valve may be at least 2, 40 or 50 times more than the throttling cross-section.
Upstream of the final valve a further valve may be provided, featuring the throttles properties. This valve too, closes microbiologically sealed, directly upstream of the medium outlet by radial pressure. The closing faces of the throttling valve are located in the region of the nozzle duct forming the medium outlet or therein. One of these closing faces may be integral with one of the closing faces of the closing gap at the medium outlet. Thus the same valve body may form a movable or openable closing face of the valve and a stationary closing face for opening the other valve, for example with the final valve open.
At least one further throttle or valve is located upstream of the above valves in the outlet duct. For example the medium fraction serving to open the valve is already pre-throttled in permanently constant throttling cross-sections while flowing on toward the throttle or the final valve. The medium is also throttled at the output or transition from the conveying chamber into the outlet duct or shut off microbiologically sealed at this transition. For this purpose a spring-loaded outlet or pressure relief valve is suitable. For forming the closing gap the closing faces of each of the valves may have only linear contact or maximum closing pressure along a sole annular line, thus resulting in maximum specific areal pressures. One of the closing faces is thus bounded in each case as a sharp edge by two angularly interconnecting flanks or by a spherical face.
The medium is manually conveyed by a thrust piston pump or a flexible squeeze container, such as a tube. In the second case the complete valve control of the dispenser is arranged in the constricted tube tip which is in one part with the tube shell. In case of a piston pump the pump cylinder or pump piston thereof is included in the pump stroke motion commonly with the medium outlet. This motion is directed counter the opening direction of the movable valve body.
A droplet former is provided with which the medium, particularly in the upside-down position of the dispenser with the medium outlet oriented downwards, accumulates into an exposed droplet of a metered volume. The droplet then hangs at a diameter suspended on the dispenser, which diameter is smaller than the largest drop diameter. Thus the drop does not detach until its lower end face comes into contact with a counter face, such as the eyeball. The droplet thus not commences to flow onto the counter face until this contact
Bui Thach H
Ing. Erich Pfeiffer GmbH
Quarles & Brady LLP
Shaver Kevin
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