GB2534543A

GB2534543A - Cafetiere

Info

Publication number: GB2534543A
Application number: GB1421752.5A
Authority: GB
Inventors: Gort-Barten Alex
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-12-08
Filing date: 2014-12-08
Publication date: 2016-08-03
Also published as: GB201421752D0

Abstract

A cafetiere is disclosed comprising a jug having an interior wall and a plunger. The plunger is provided with two spatially separated filters 3, 4. Each filter comprises a sealing means 7, which biases a mesh filter 6 against the inner wall of the jug. In use, the pressure exerted by one of the sealing means is greater than the pressure exerted by the other sealing means. This arrangement is designed to minimise the number of coffee grounds that bypass the filters and contaminate the coffee. The separation between the filters may be 10-35mm. One of the filters may have a finer filter mesh than the other filter.

Description

Intellectual Property Office Application No. GII1421752.5 RTM Date:23 March 2015 The following terms are registered trade marks and should be read as such wherever they occur in this document: Tesco Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo Cr) O

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Cafetiere The invention relates to a cafetiere.

Cafetieres are one of the most popular ways of making coffee. An early example of a cafetiere is disclosed in CA343480 and further refinements are disclosed in US 2900896. The basic concept still remains of having a filter attached to a plunger able to slide like a piston in a container holding ground coffee and using boiling water to extract the coffee. The filter is biased against the interior wall of the container by resilient means such as a spring around its periphery to prevent liquid leaking past the edge of the filter and also to permit the filter to be pushed down using a moderate amount of force. The filter in these early designs usually comprised a two part filter with the first filter to catch the coarser grounds and a second above the first to catch finer grounds. After the coffee has been extracted the plunger is depressed so that the coffee grounds remain below the filter and the extracted and filtered coffee above.

Later designs dispensed with the second filter as it was found that the second filter did not affect the filtering performance but was significantly harder to clean. An example of such a cafetiere can be found in USD 493662.

Known cafetieres suffer from a number of known problems, in particular the plunger can be difficult to press down if the coffee is of reasonable strength. It is also a common problem that the filtration is not complete and the poured coffee contains ground coffee. Attempts to mitigate this with a filter on the spout have not been too successful.

The present invention therefore seeks to provide a cafetiere that requires less force to he exerted on the plunger than commonly available designs as well as providing good filtration.

According to the invention there is provided a cafetiere for extracting coffee from coffee grounds in hot water comprising a jug having an interior wall and a plunger, which plunger comprises first and second filter arrangements, each of said filter arrangements being provided with a filter having a circumferential edge biased against the interior wall by respective biasing means to thereby provide respective sealing means, wherein the second filter is spatially separated from the first filter such that the second seal, wherein in use the sealing pressure of the respective sealing means is a function of pressure exerted by the biasing means on the interior wall and pressure exerted by coffee grounds being extracted in the water such that the pressure exerted by the second sealing means is, in use, greater than the pressure exerted by the first sealing means.

Preferably, the first and second filter arrangements are separated by 10-35 mm.

Preferably, the second filter arrangement is provided with a finer filter than the first filter arrangement.

The invention advantageously provides that the second seal is de-pressured with respect to the first seal, which surprisingly provides an improved sealing mechanism.

Cr) An exemplary embodiment of the invention will now be described in greater detail O with reference to the drawing in which:

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Fig. 1 shows a cafetiere plunger Figure 1 shows a cafetiere plunger comprising a lid 1 connected to a rod 2, which rod is vertically disposed in use. The distal end of the rod 2 is provided with a first filter arrangement 3 and spatially separated from the first filter arrangement, a second filter arrangement 4. The filter arrangements 3 and 4 are fixed to the rod 2 and are hence substantially co-planar. Each filter arrangement 3, 4 comprises a base plate 5 having a circular shape, the circumference of which corresponds to the inner circumference of the cafetiere jug. A respective mesh filter 6 is mounted on the respective base plate 5, the circumferential rim of the filter being upturned towards the lip 1. A coil spring 7 is then provided to bias the upturned circumferential rim against the inner surface e of the cafetiere jug in use.

Due to the methods of manufacture of the cafetiere, there is an internal draft of between 2 to 5 degrees from the top to the bottom. The jug interiuor walls are not

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vertical but that the internal diameter at the top of the jug is greater than the internal diameter at the bottom of the jug. The use of the spring ensures that the filter remains in contact with the interior wall.

A connector piece 8 having a hexagonal nut feature is located on the rod 2 between the first and second filter arrangements. The nut feature can he used to tighten the filters into position upon assembly.

The first and second filter arrangements are spatially separated by approximately 30mm to facilitate cleaning and to avoid producing a finger trap.

In a comparative study with a known cafetiere, the following steps were taken: Weigh the filter papers and add filter to a filter coffee cone.

* Add 50g of ground coffee, ground for filter coffee, to the cafetiere.

* Add 875m1 of boiling water to the cafetiere, making 7x 125m1 cups.

* Leave cafetiere for 4 minutes before plunging so the coffee is extracted.

* Plunge coffee and pour into the coffee filter cone.

* Wait for the coffee to drain out and leave it to dry for 24 hours.

* Weigh the filter.

* Subtract the filter weight from the total weight.

This gave the tollowing results Single: as supplied Tesco Single 19% Double Top: 180 lid

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Bottom: 80 Sample Bottom: 80 3 Double 875 50 3 22% Top:150 As can he seen from the table above, there is an improvement of around 19-22% by the use of the invention.

It is believed that the predominant cause of ground coffee leaking past the filter occurs at the start of the plunger travel as the filter seal is not as good due to the draft of the jug interior wall. It has previously been understood that the sealing pressure was provided by the spring and so the provision of a second seal was redundant as it would provide less sealing pressure due to the draft of the jug. However, it has not been previously understood that the build up of grounds under the (first) filter contributes significantly to the effort required to use the plunger and also helps (r) diminish the effectiveness of the seal being formed between the wall and filter arrangement. Although the seal should then notionally improve, once the seal

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between the filter and the wall is broken, it frequently stays broken. This causes the CO grounds to be forced above the filter into the extracted coffee. The provision of the C\J second filter arrangement advantageously solves this problem as the quantity of coffee grounds that escapes past the first filter is reduced and so causes less of a reduction in the sealing pressure of the spring. This in turn permits the use of a finer filter in the second filter arrangement than would be possible with the first filter arrangement reducing the quantity of coffee grounds in the coffee that is poured.