Dispensing – With discharge assistant – Plural
Reexamination Certificate
1996-09-20
2001-10-16
Bomberg, Kenneth (Department: 3754)
Dispensing
With discharge assistant
Plural
C222S256000, C222S321900, C222S382000
Reexamination Certificate
active
06302304
ABSTRACT:
FIELD OF THE INVENTION
This disclosure relates to dispensing systems in which a pump dispenses flowable material from a container, the material being fed to the pump through a feed tube extending down into a container.
BACKGROUND
When thick or viscous products (such as gels, creams and pastes) are dispensed they do not always flow freely to the feed-tube intake. This can lead to unreliable dosing and difficulty in clearing the last part of the product from a container. It is therefore known to provide a follower plate which fits slidably around the feed tube, sealing inwardly against the feed tube and outwardly against the container side wall. The plate lies on top of the product mass to ensure that withdrawal of a volume of product through the feed tube inlet (at the container base) causes a uniform fall of the product surface. Without the follower plate, and particularly when dispensing is rapidly repeated, local voiding near the feed tube would tend to leave inaccessible product residues up the container side wall.
Even with follower plates, however, it has been found that undispensed product residues can be undesirably high and undesirably variable.
SUMMARY OF THE INVENTION
Our aim is to Provide a new dispensing system, using a follower plate and giving a more reliable reduction in non-dispensed residue.
The system generally comprises a container having a base and a side wall, to hold flowable material for dispensing, a dispenser pump mounted at the top of the container, a feed tube extending in the container down from the dispenser pump intake to the container base to convey product from the container into the pump, and a follower plate fitting axially slidably around the feed tube and extending out to the container's side wall, to follow the surface of the product down the container as dispensing proceeds.
Our proposal is that the foot of the feed tube interlocks with the container base. We have found that a significant cause of non-dispensed product is inhibition of movement of the follower plate caused by sideways movements of the feed tube in the container, e.g when a user pushes or twists the pump sideways. By providing an engagement of the tube foot with the container base to prevent such sideways movements, freedom of the follower plate is better assured and performance can be improved.
The interlock engagement may take any suitable form provided that it prevents lateral movement, since even a small deviation can hinder the follower plate. Typically this requires a fitting engagement, with laterally-directed parts of the tube fitting against laterally-directed parts of the base. The connection may however allow relative axial movement and/or rotational movement around the tube axis, particularly since these are usually needed for installing the tube in the container. An interference fit is possible but may hinder installation, so an exact fit is ideal and a slight clearance fit is usually practical. To facilitate installation, one or both of the tube foot and container base may provide tapered guide surfaces to lead the other component into fitting engagement with the fitting surfaces on installation.
The preferred version uses one or more upward projections of the container base to engage and fit inside or outside the tube foot's periphery, which is typically annular. A standard plain feed tube may then be used, only the container needing modification.
The feed tube must of course provide one or more product intake openings, and these are generally down at the container base to ensure full product clearance. The foot/base engagement construction needs to provide clearance for this. This may be achieved by a circumferentially segmented engagement, e.g circumferentially-spaced interlock segments projecting up from the container base. The narrower the segments, the less the criticality of rotational alignment between foot and base. So, a preferred construction uses a set of circumferentially-spaced, circumferentially-localised lugs or fins whose radially-directed edges make the interlock engagement.
Radially-directed fins can be provided on the base to engage either outside or inside the tube foot. A A simple and strong construction has a single central upward projection with radially-directed fins in cruciform or stellate arrangement. This projection can have a convergent top to give the guiding referred to above. The engaging parts of the base and tube foot are preferably complementarily shaped.
The components can be made by standard plastics moulding techniques.
The other components of the arrangement may be conventional.
The follower plate can be a flat plate with upwardly-flared sealing lips at its inner and outer peripheries, to seal against the feed tube and container wall respectively. However other forms of seal or follower plate may be used.
The container is typically but not exclusively cylindrical. The feed tube may be central.
The pump may be of any suitable type. One preferred form has a pump body which seats into a cap to cover the container opening. The pump chamber may extend down into the container. The feed tube may be provided by a tubular component which sits onto a spigot at the pump body inlet, or may extend up around the pump chamber as a housing for or part of the pump.
The pump is typically plunger-operated, with a fixed or movable dispensing nozzle mounted above the container, but this is just one preferred option. Indeed, a pump could be separately mounted provided that its feed from the container top originates with the feed tube.
Aspects put forward for protection here include not only the dispensing system as a whole but also the combination of container and feed tube (with or without the follower plate) adapted to engage one another as aforesaid, and also a container whose base is provided with one or more upstanding engagement projections as described herein.
REFERENCES:
patent: 1804582 (1931-05-01), Woodruff
patent: 1977360 (1934-10-01), Talbot
patent: 2154325 (1939-04-01), Crothers
patent: 2268592 (1942-01-01), Hothersall
patent: 2810496 (1957-10-01), Gray
patent: 4728008 (1988-03-01), Graf et al.
patent: 4750532 (1988-06-01), Grothoff
patent: 4817829 (1989-04-01), Fuchs et al.
patent: 5197637 (1993-03-01), Naumann
patent: 0 213 476 A2 (1987-03-01), None
patent: 0 262 535 (1988-04-01), None
patent: 0 499 538 A1 (1992-08-01), None
patent: 2 510 071 (1983-01-01), None
patent: 959835 (1964-06-01), None
patent: 5319466 (1993-12-01), None
A brochure from “Englass Dispensing & Packaging Systems”, Leicester, England, Jan. 4, 1993.
Adusei-Poku Kwadjo
Bomberg Kenneth
Doigan Lloyd D.
Rieke Packaging Systems Limited
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