Liquid purification or separation – Filter – Resting on supporting receiver – e.g. – portable
Patent
1996-12-05
1998-06-23
Walker, W. L.
Liquid purification or separation
Filter
Resting on supporting receiver, e.g., portable
210477, 210480, 210482, 99297, B01D 3301
Patent
active
057700745
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/GB95/01255, filed Jun. 1, 1995 which designated the U.S.
The present invention relates to filter apparatus and in particular, but not exclusively, to filter apparatus for the preparation of beverages such as coffee.
There is currently known a variety of methods of preparing a beverage such as coffee. One of the most common methods involves the use of a receptacle into which hot water and coffee are introduced. Then, at the appropriate time, a plunger is inserted into the receptacle and pushed downwardly through the liquid in the receptacle from an upper opening of the receptacle to a base region of the receptacle. The plunger includes a plunger head which has a filter element and this serves to filter the liquid during the movement of the plunger downwardly within the receptacle. This downward movement of the plunger, with its associated filter element, seeks to collect, and retain, coffee grinds and other solid particles that should be kept separate from the beverage to be eventually dispensed.
Such known apparatus is however disadvantageous in that the plunger does not successfully prevent the passage of coffee grinds, and other material, into the region of the receptacle from which the beverage is eventually dispensed. In particular, as the plunger is moved downwardly within the receptacle, the build-up of pressure in the liquid below the downwardly moving plunger serves to open an access path for coffee grinds and other material to by-pass the plunger, i.e. pass through a gap formed between the outer periphery of the plunger and the inner surface of the receptacle.
This is particularly disadvantageous in that it provides for a potentially poor-quality beverage having coffee grinds and possibly other solid material present therein. Further, the passage of the coffee grinds and other material, via the gap formed between the outer periphery of the plunger and the inner wall of the receptacle, also serves to scratch and disadvantageously spoil the appearance of the inner surface of the receptacle so that the receptacle quite readily takes on the appearance of a well-used, old and generally unclean receptacle.
Metal filter plunger members are commonly known but are restricted in their use since it is generally not feasible to use such filter plunger members with polycarbonate beakers which tend to exhibit a decrease in internal diameter with depth.
The present invention seeks to provide filter apparatus having advantages over currently available filter apparatus.
According to one aspect of the present invention there is provided filter apparatus comprising a receptacle for liquid to be filtered and having outlet means by which filtered liquid can be dispensed therefrom, plunger means having filter means and arranged for movement within said receptacle and through said liquid so as to filter said liquid, said plunger means being provided with a skirt portion for contacting the inner surface of said receptacle during said movement of said plunger within said receptacle, and wherein said skirt portion is arranged to extend away from said filter means and in the direction of movement of said plunger means during the filtering of said liquid, and to be biased towards the inner surface of said receptacle by the pressure of the liquid being filtered during said movement.
The invention is particularly advantageous in that, as the plunger is moved through the liquid so as to effect the filtering action, the liquid being filtered can act so as to force the skirt region of the plunger outwardly and into contact with the inner surface of the receptacle and this advantageously assists in seeking to greatly inhibit the passage of any solid material past the outer periphery of the plunger means. The improved sealing between the plunger means and the inner surface of the receptacle advantageously substantially reduces the amount of solid product found in the filtered liquid.
Advantageously, said skirt portion is arranged to flair outwardly from the fil
REFERENCES:
patent: 2935928 (1960-05-01), Keating et al.
patent: 4733792 (1988-03-01), Wasserman
patent: 4764391 (1988-08-01), Wasserman
patent: 4821630 (1989-04-01), Roberts
Brasilia (UK) Limited
Walker W. L.
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