EP4648655A1

EP4648655A1 - Device for distributing water onto and compressing a mass of coffee grounds, a coffee machine and method of making coffee

Info

Publication number: EP4648655A1
Application number: EP23915215.0A
Authority: EP
Inventors: Gregory Grochola
Original assignee: Optex Solar Pty Ltd
Current assignee: Optex Solar Pty Ltd
Priority date: 2023-01-13
Filing date: 2023-12-22
Publication date: 2025-11-19
Also published as: WO2024148392A1; CN120529852A; AU2023423919A1

Abstract

A device for distributing water onto and compressing a mass of coffee grounds compacted in a collection basket, the device configured to be at least partially received in the collection basket and formed of a shell having an upper shell component with at least one opening through which pressurised water flows from a coffee machine and a water pervious lower shell component for contacting the mass of coffee grounds, the shells defining at least one cavity therebetween in which water can flow, wherein within the shell there is formed a constriction in a path of pressurised water flow so that in use the device is urged against the coffee grounds by water pressure pressing on the shell as a means to transfer and impart a linear force against the coffee grounds and distribute water generally evenly over the grounds.

Description

Device for distributing water onto and compressing a mass of coffee grounds, a coffee machine and method of making coffee

Field of the invention

The present invention relates to a device for distributing water onto and compressing a mass of coffee grounds compacted in a collection basket, a coffee machine and a method of making coffee.

Background

Coffee is one of the most consumed beverages worldwide. Various extraction means and methods exist to extract soluble components from coffee grounds (a powdered form of coffee beans created by grinding roasted coffee beans finely). It is well known that various combinations of soluble components can be extracted, and this depends on the exact extraction means and methods. Said combinations form distinct and desired taste profiles in coffee drinks. One method with a particularly desirable and popular taste profile is termed espresso, and it involves forcing hot water at high pressure through a compacted cylinder of coffee grounds, termed a puck, typically at 5-20 bar water pressure sitting inside a perforated collection basket commonly referred to as a portafilter basket.

Typically, the means to do this involves a mains-powered espresso machine, which includes a water supply, a heater, a pump, and facilities to hold the coffee grounds in place while forcing hot water evenly through said grounds. Alternatively, espresso can also be extracted using various hand-operated espresso machines, which use various mechanical leverage means to generate the 5-20 bars of water pressure required to force water through said grounds.

What is not known in the art is that all espresso machines rely on three critical layer structures formed spontaneously inside said puck and portafilter basket during extraction. The first, termed here bottom layer structure, is a thin ultra-fine filter layer that is formed during extraction as ultra-fine ground coffee particles build up and clog the portafilter basket perforations. The second termed here central layer structure is substantially the central layer of the coffee puck where the grounds are substantially linearly compressed during extraction closing off larger water gaps between the particles, the third, termed here top layer structure, is the surface layer of the puck that is initially exposed to water. This last layer typically comprises one-quarter to one-half the thickness of the puck and thickens during extraction as ultra-fine particles are gradually evacuated during extraction. The critical action of said top layer structure is to form a layer of grounds that substantially resists water flow and hence creates a layered compressive piston like effect that provides a linear compressive back-pressure force of typically 1 to 9 bars on the remaining three- quarters to one-half of the puck (depending on depth from the surface and time during the shot). It is this compressive back-pressure force that squeezes the said central layer structure and restricts the water channels between the coffee particles in this layer; it also helps to stabilise said bottom layer structure by preventing water from getting underneath coffee particles and hence washing them out of said perforations. Restricting the water channels in between said coffee particles creates a pressure gradient across the particle itself, which forces water to flow through said coffee particle as opposed to around said coffee particle; this liberates and forces coffee solutes (and non-solutes) from inside the particle's molecular matrix structure, creating an excellent extraction and a delicious espresso taste.

It has been observed, however, that even with an optimal traditional espresso extraction, there exists a fraction of coffee particles in said top layer structure that do not and cannot experience the conditions that result in full extraction; instead, they experience flow conditions that result in sour, watery espresso, where water typically flows around said coffee particles and not through said coffee particles. It is only by the saving grace that the remaining central layer structure, forming the better half of the total puck's weight, experiences said compressive back-pressure force and hence recovers the taste. Therefore, even the best traditional espresso extraction process today is the result of a mixture of well -extracted and poorly extracted grounds. It has also been discovered that there is a further, more serious problem with the traditional espresso process, in that it is reliant on the formation of said three critical layer structures and that the formation processes and resulting structures are delicate and metastable. For example, if the ground particle size is too large, the top layer structure will not provide sufficient resistance to water flow and hence will provide an insufficient compressive back-pressure force on said central layer structure, which is needed to restrict water channels between the ground particles. This will also hinder said bottom layer structure from forming an ultra-fine filter, as water can easily get "underneath" said ground particles, creating larger flow macroscopic water channels through the puck. In the espresso field, this is termed channelling. If, on the other hand, the ground particles are too fine, then there may be an excessive compressive back-pressure force from said top layer structure coupled with an excess of ultra-fine particles, which not only blocks the portafilter basket perforations, but secondly blocks even the smallest microscopic water channels in the central layer to such an extent as to prevent the flow of submicron colloid suspensions which provide important taste and "body" producing espresso characteristics. Both scenarios result in terrible-tasting espresso; the first results in weak, watery, sour espresso, as water has not passed through the ground particles but instead passed around the ground particles, dissolving the outside surface excessively. The second results in a bitter espresso as water takes too long to flow through said puck and hence spends too long in contact with the grounds bringing out bitter flavour notes.

Hence, in traditional espresso, there is a well-known requirement for a "dial-in" process, where the grinder is finely adjusted, and multiple successive extractions are trialled with the aim of finding a single grind setting on a precision grinder that will produce an extraction process where an ideal amount of espresso liquid is obtained within a set time, typically to produce an espresso with a 1:~2 ratio, within about 20-40 seconds (termed here proper expresso timings). Espresso "ratio" defined here as the starting grounds dose weight to end espresso liquid weight. This is performed for some set pre-defined "pressure profile curve," typically peaking at 9 bar pressure with a low-pressure pre-infusion phase and sometimes with a tapering pressure toward the end of the extraction. Finding this ideal grind setting creates waste and, secondly, requires a barista with training and experience in diagnosing extraction issues, but also thirdly necessitates the need for expensive grinders with precision grind micro-adjustment settings.

An aim of embodiments of the present invention is to address these issues by replacing said top layer structure using physical means that are not dependent on the spontaneous and metastable formation of these two said critical layer structures. In so doing, we replace said meta-stable top layer structure with a stable but adjustable compressive force on the surface of the puck, which, when tuned property throughout the extraction process, may provide an ideal amount of compressive back-pressure force for any particular grind settings to, firstly, recover proper espresso timings, but secondly to close off larger water gaps between coffee particles so as to force water to flow through the particle's molecular matrix structure itself, resulting in excellent extraction and espresso, as well as eliminating the need for a "dial-in" process, a trained barista, and expensive precision grinders. Lastly, we also optionally replace said bottom layer structure with a fine filter to prevent the blocking of the portafilter perforations if the grind is too fine, which can also broaden the grinder setting that can be used.

According to one aspect of the invention there is provided a device for distributing water onto and compressing a mass of coffee grounds compacted in a collection basket, the device configured to be at least partially received in the collection basket and formed of a shell having an upper shell component with at least one opening through which pressurised water flows from a coffee machine and a water pervious lower shell component for contacting the mass of coffee grounds, the shells defining at least one cavity therebetween in which water can flow, wherein within the shell there is formed a constriction in a path of pressurised water flow so that in use the device is urged against the coffee grounds by water pressure pressing on the shell as a means to transfer and impart a linear force against the coffee grounds and distribute water generally evenly over the grounds. According to a preferred embodiment, the device further includes means within the at least one cavity to disperse water radially outwardly from the at least one opening around the at least one cavity.

The device can further include a water pervious support structure within the at least one cavity to prevent collapse of the upper or lower shells. Preferably, the device further includes a seal extending around a periphery of the device to seal the device within the collection basket or within an upper group head chamber to create a pressurised space above the upper shell of the device.

Preferably, the upper shell component is formed of multiple layers each having perforations formed therein and at least one of which has water distribution channels formed therein to distribute water within the at least one cavity. Preferably, the constriction path is formed in the upper shell component, though it may be formed in an intermediate part between the upper shell component and the lower shell component.

The device can be configured to be received against a group head of an espresso machine, wherein the shell is at least partially retained within a housing secured to the head and is free for vertical movement to bear against the coffee grounds, the device including a seal extending around a periphery of the shell to seal the shell within the housing secured. The device can further include a retainer having an outer dimension larger than an inner indented portion on the housing and one or more fastener holes through which one or more said fasteners holds the said retainer in place, and the said retainer larger outer dimension holding the housing in place.

The device can further include at least one retraction spring between the head of the espresso machine and the shell to retract and/or retain the shell after use. The device can further include a pressure releasing means so that the device is not forced out of the secured housing during flushing of a group head, if there is no basket and compressed coffee grounds secured inside the espresso machine group. In some embodiments, the device further includes an upwardly extending guide in association with the upper shell component for restricting movement of the shell to a generally vertical axis.

The device can further include an integrated non-return valve on each of the at least one opening present on the upper shell component of the device, and/or a needle flow adjustment valve, and/or a constant flow valve, and/or a removable nut with one or more integrated constrictions, and/or a reduced flow with greater pressure valve.

According to another aspect of the invention there is provided a method of making coffee, comprising the steps of: providing a device of the above described type; providing pressurised, heated water into the opening in the upper shell; and collecting coffee flowing from the basket.

According to another aspect of the invention there is provided a coffee machine, comprising: a device for distributing water onto and compressing a mass of coffee grounds compacted in a collection basket, the device configured to be at least partially received in the collection basket and formed of a shell having an upper shell component with at least one opening through which water flows from the coffee machine and a perforated lower shell component for contacting the mass of coffee grounds, the shells defining at least one cavity therebetween in which water can collect; and means for imparting reciprocal movement to the device to urge it against the coffee grounds to impart a linear compressive force thereto and distribute water generally evenly over the grounds.

Preferably, said means includes a secondary and independently adjustable source of pressurised fluid introduced into the space above the device. Preferably, said means includes a linear actuator for displacing the shell. According to another aspect of the invention there is provided a method of making coffee, comprising the steps of: providing a coffee machine of the above described type; providing pressurised, heated water into the opening in the upper shell; applying a compressive force to the device to maintain pressure against the coffee grounds; and collecting coffee flowing from the basket.

Preferably, the method further includes the step of monitoring the water pressure inside the at least one cavity, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds and varying the compressive force exerted onto the surface of the mass of coffee grounds to achieve a water pressure, and/or a flow rate, and/or a cumulative liquid amount within a predetermined range.

In some embodiments, the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is approximated by monitoring the water flow rate flowing to the mass of coffee grounds, and/or the cumulative water amount that has flowed to the mass of coffee grounds using a flow meter.

In other embodiments, the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is approximated by monitoring the coffee flow rate from the basket, and/or the cumulative coffee amount that has flowed from the basket using a weight scale.

According to another aspect of the invention there is provided a method of making coffee, comprising the steps of: providing a mass of coffee grounds in a collection basket; applying a compressive force to the grounds during extraction with a perforated device through which water can flow; flowing heated water through the device so that the water flows through the grounds under pressure to brew coffee; and collecting the coffee, wherein the water pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is monitored and the compressive force applied to the grounds by the device varied to keep the water pressure, and/or flow rate, and/or the cumulative liquid amount within a predetermined range.

In some embodiments, a compressive force is applied to the grounds via a variable force actuator.

In some embodiments, a computational algorithm that monitors and calculates the amount of compressive force applied to the mass of coffee grounds by the device during extraction involves comparing the device's internal pressure, and/or the liquid flow rate that is flowing through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds, to a predetermined pressure profile curve, and/or a flow rate profile curve, and/or a cumulative liquid amount profile curve at multiple time points during the extraction, and if the pressure, and/or the liquid flow rate, and/or the cumulative liquid amount is found to deviate by some amount then some stepped change in compressive force is applied to the mass of coffee grounds.

Preferably, the said some stepped change in compressive force applied to the mass of coffee grounds by the device for any said deviation from said curve(s) is determined through a self-learning algorithm calculated over multiple extractions.

Preferably, the coffee machine remembers the pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds at some time point during the extraction and uses that information in subsequent extractions to adjust the compressive force applied to the mass of coffee grounds by the device so that some predetermined pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds can be obtained at some time point during the extraction.

In some embodiments, the adjusted compressive force applied to the mass of coffee grounds by the device for some said subsequent extraction is determined through a selflearning algorithm which uses one or more past extractions to determine a relationship between the compressive force applied to the mass of coffee grounds and the pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds at some time point during the extraction.

Brief description of the drawinas

In order that the invention may be more easily understood, many embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure la is an upper perspective view of a device for distributing water onto a mass of coffee grounds according to one embodiment of the invention;

Figure lb is a lower perspective view of the device; Figure lc is a side sectional view of the device;

Figure Id is a side view of the device;

Figure le is an upper perspective view of the device with an upper shell component removed;

Figure 2 is an upper perspective view of the device received in a collection basket which holds coffee grounds;

Figure 3 is side sectional view of the device installed in a collection basket;

Figures 4a and 4c are perspective views of a disc which may form part of an internal structure of the device;

Figures 4b and 4d are perspective views of another disc which may form part of an internal structure of the device;

Figures 5a to 5g are side sectional views of alternatively constructed devices for use as a replacement dispersion screen;

Figure 6 is a perspective view of an alternative seal for use with the device;

Figure 7 is an alternative cylindrical housing incorporating pressure release means;

Figures 8a and 8b are side sectional views of an alternative device, incorporated into a coffee machine;

Figures 9a to 9c are sectional views of flow pressure nut for varying back-pressure on the device to be used with any of the described devices;

Figure 10 shows flow vs pressure characteristics of the various valves that can be used with the described devices;

Figures 11a to lid are side sectional views of another alternative device which is also incorporated into a coffee machine;

Figures 12a and 12b are side sectional views of an alternative device, incorporated into a coffee machine; and

Figures 13a to 13c are side sectional views of alternative configurations of a fine filter disk to be used in combination with embodiments of the described device;

Figure 14a is an upper perspective exploded view of a device for distributing water onto a mass of coffee grounds according to another embodiment of the invention; Figure 14b is a lower perspective exploded view of the device;

Figure 14c is a side sectional view of the device.

Detailed description

The embodiments described herein and shown in the Figures are all described from the perspective of top-down coffee machines, i.e. machines in which the water flows in a downward direction. However, it will be appreciated that the present invention is not limited to machines of this type and it can also be used in coffee machines that are otherwise orientated, such as a bottom-up machine, i.e. one in which the water flows in an upward direction.

A removable device 10 according to a preferred embodiment of the invention is shown in Figures la to le. The device 10 is configured for distributing water onto a mass of coffee grounds 50 compacted in a collection basket 28 (Figure 2).

The device 10 is configured to be at least partially received in the collection basket 28 (otherwise known as a portafilter basket) and is formed of a shell having an upper shell component 12 and a pervious lower shell component 14. The upper shell component 12 has at least one constrictive aperture or opening 16 through which pressurised water flows from the espresso machine. Although a single constrictive opening 16 is illustrated, it will be appreciated that multiple apertures or internally formed constriction channels of different sizes may also be provided to result in the same flow constrictive effect.

In use, water flows under pressure from a coffee or espresso machine into space 44 where it pressurises and flows into opening 16. The opening 16 in the upper shell component 12 forms a constriction in the path of water flow so that in use, as pressure builds in space 44, pressure is applied onto the upper surface of device 10 which is hence urged against the coffee grounds or puck 50 by the said water pressure to impart a compressive force against the coffee grounds. In an alternative embodiment, an intermediate disk may be placed below the upper shell component 12, wherein the constriction path of water is formed via tight spacings or channels between the two and whereby pressure is hence formed and is imparted on to the device 10 to compress the coffee grounds.

Further, water flows through the constrictive opening 16 into a cavity 20 defined between the upper 12 and pervious lower 14 shells and hence distributes in said cavity 20. By imparting pressure against the puck 50, device 10 acts as the above-described top layer structure, compacting the top layer to ensure effective flow of water through the top layer coffee particle's internal molecular structures, instead of through spaces around the coffee ground particles, as well as providing for the ability to manipulate the puck's resistance to water flow. In a preferred embodiment, the opening 16 is of a constricted aperture chosen to produce 1 to 12 bars of pressure force against the upper shell component 12 when exposed to a 1.33mL/s steady state water flow rate. The exact overall pressure to flow characteristics can be chosen by the user via an adjustment mechanism described below or via the supply of a multiple set of such devices with different size aperture opening 16. To ensure that the device 10 can withstand such pressure, device 10 may be provided with an internal support structure 26 to prevent internal collapse of the device 10. The illustrated support structure 26 is a spiral shaped tape spring, though it will be appreciated that the support structure 26 may take other forms and shapes, and in fact a support structure could also be integrally formed into the upper and/or lower shells in the form of indent patterns/channels that act like support structures.

Device 10 can provide a physically stable, non-diminishing, compressive force on the puck's 50 surface during extraction, replacing said unstable top layer structure which degrades in the compressive force it provides during the shot since ultra-fine particles and solutes are constantly being evacuated from this layer during extraction.

The coffee machine may be configured to electronically monitor the water flow through the puck, using one or more back pressure gauges and/or a flow gauges and/or espresso liquid weight scales during extraction such that if the flow rate is excessive, the machine can introduce a momentary burst of increased flow and hence pressure which will increase the compressive force on the puck's surface via the device 10, by virtue of the constrictive aperture 16. This compacts the puck 50 and ultimately decreases the flow rate to recover proper espresso flow timings. To promote this proposed ability of the machine to manipulate the puck's resistance to water flow during extraction via changes in pump flow rate, various different flow behaviour valves can be used in place of the simple aperture 16 discussed so far. These include for example, a constant flow valve, and/or even a flow reduction valve configured to reduce the flow of water if the pressure reaches higher pressures, these will be described below.

Radially extending grooves 19 are illustrated in Figure la, though these may be omitted in other embodiments. Grooves 19 can provide water distribution channels to direct the incoming water from aperture 16, radially outward for proper distribution across the cavity 20 between the upper and lower shells. They can also provide an integrated supporting structure and hence in some cases eliminate the need for a said separate internal support structure 26 altogether.

The lower shell component 14 is pervious to liquid and allows water to flow therethrough and contact the puck 50. In the embodiment shown in Figure lb, the lower shell component 14 is thin and perforated and it will be appreciated that the thickness and number and size of perforations may vary. Also, the lower shell component 14 may be otherwise constructed, as for example a layer of partially fused microspheres that allow liquid to pass therethrough.

The shell components 12, 14 are substantially flat though may be slightly curved and define a cavity 20 therebetween in which water can flow. As water flows through into the constrictive opening 16, it moves as a high-pressure jet hitting the contact deflector/distribution disc 22 which may distribute water radially outwards within cavity 20. By distributing water evenly within cavity 20, a more even flow of water through the device and to the puck may be achieved. Shell components 12, 14 have a wall section so that when device 10 is assembled, it has a thickness or cylindrical height in the order of 5mm to 15mm in the preferred embodiment. A circumferential seal 24 is provided around device 10 to seal the device 10 within the collection basket 28 and to ensure that pressure can build above the upper shell. A groove may be formed in the wall sections to accommodate the seal 24.

The device 10 of Figures la to le is particularly suitable for use in bottom-up coffee machines, though its use is not limited thereto. In use for such machines, water floods up and evenly self-distributes through the action of gravity. Grooves in the upper shell component 12 may be provided though may not be essential. The device can also be used in a top to bottom flow coffee machine wherein water is initially distributed radially via the disc 22 upon entering cavity 20, but it also pools in cavity 20 during pre-infusion and through the action of gravity distributes evenly across the puck's surface before the application of full pressure.

As illustrated in Figure 3, the above-described bottom layer structure can optionally also be replaced using a thin fine filter disk 18, positioned between the base of the collection basket and the puck 50. This can preferably be a paper filter, and it can be used in conjunction with said device 10 but is not strictly required and standard portafilter baskets 28 can be used. An optional alternative can also be to use an increased number of perforations than is commonly used in standard collection baskets 28. It is important to point out that the use of such a fine filter disk 18 or an excess number of basket 28 perforations without device 10 would require a finer grind to achieve desired shot times. Such a scenario is undesirable as it allows for the migration of ultra-fine particles into the espresso which introduces astringent tasting notes. Device 10 places a back-pressure force on the puck which locks ultra-fine particles in place preventing their migration, and the fine filter 18 prevents the baskets perforations from getting clogged with fine coffee grounds. Hence, while device 10 allows for courser grounds - the fine filter disk 18 allows for finer grounds to be used, and therefore their combined usage allows for a wider range of grind setting. Essentially, we are replacing both said top and bottom layer meta-stable structures, with stable structures (that do not change with grind size) resulting in ideal microscopic flow characteristics through the entire coffee puck's 50 thickness and hence a consistently ideal expresso.

In alternative embodiments, the lower shell component 14 and/or the support structure 26 can be designed specifically to make the surface of the device more flexible in conforming to the surface of the puck. In one example, the lower shell component 14 is formed from flexible material. The upper shell component 12 may also be formed of a flexible material, though this is not essential. In some embodiments, the lower shell component 14 and support structure 26 can be made from multiple layers of fine, sparse metal mesh that gives the outer surface of the device a spring-like characteristic, or a layer of magnetically retained metallic particles, spheroidal or otherwise, that conforms to the surface of the puck and provide a constant back-pressure force at each point on the surface of the puck. Alternatively, the support structure 26, 126, 226 or 326 can also be formed of a set of short small, diameter springs or flexible elastomeric pillars and/or the lower shell component 14 formed of a pervious flexible material so that in total, the construction provides for a more flexible and conforming outer surface which rests on the puck. Nitinol with a low transition temperature (below 80DegC) is particularly useful as a construction material here.

The device 10 may incorporate a pre-filter 76 prior to the constriction to prevent clogging. The filter may be incorporated into the upper shell component 12 or be a separate part.

Figure 3 illustrates another embodiment of device 10 installed within a collection basket 28 connected to a typical e61 group head 30 of a commercial espresso machine. The group head 30 is shown with a group head distributor screw 46 but without the typical dispersion screen (also known as a shower screen) as it's now not required. (It should be noted device 10 can also be used with the standard shower screen in place however a deeper traditional basket may be required to accommodate the extra height taken by the device 10 inside the basket 28). The collection basket 28 is received against group head seal 40 in a typical fashion via the portafilter (not shown) and an alternative seal 24 extending around a periphery of the device 10 is used and which is of the self-energising type, i.e., with a flap and an indent and or a leading bulge on a leading outside edge so that when inserted into said basket 28 said leading edge bulge wipes away any coffee grounds so that the self-energising edge has a better seal. One or more standard O-rings can also be used.

Figures 4a to 4d show an alternative configuration of an internal structure of the device 10. This internal structure includes two perforated discs, 32, 34 that are configured to promote even distribution of water inside cavity 20. Upper perforated disc 32 has distribution channels 36 formed therein with through hole perforations formed at ends of the channels 36. Figures 4a and 4b illustrate the alignment of the perforated discs 32, 34, whereby water flowing through the holes formed at ends of the channels 36 on disc 32 pass into channels 36 formed in disc 34. Though it will be appreciated that one or both of these distribution discs may be omitted and replaced with a simple flat non-perforated section integrally formed within a central area of the lower shell 14 to act as a distribution deflector (not shown in the figures).

An underside of disc 32 is shown in Figure 4c and a ring-shaped groove 36 can be seen to allow water passage to the second set of smaller distribution channels 36. Figure 4d illustrates the distribution of through holes on the underside of disc 34, the through holes being at ends of the smaller distribution channels 36.

In the embodiment of Figure 3, the lower shell component 14 may be formed as two layers, an outer layer touching the surface of the coffee puck 50 and which is preferably of a finer filter grade to prevent the build-up of grounds deep inside the device 10. The outer layer can be, for example, a perforated structure or formed from multiple layers of compressed microspheres, or a porous ceramic, or a periodically replaceable paper filter, designed to create thousands of water channels. The paper filter can be formed of a thicker grade of paper or an open cell elastomeric (or Nitinol) sponge to give the outer layer a more flexible and conforming nature while yet still remaining pervious to water. An inner layer that acts like a support structure is made preferably of a particularly porous material to allow completely free water passage and may be made of a sparse metal mesh, a metal frame, an array of vertical uprights or a flat coiled spring 26 as in the first embodiment.

Figures 5a to 5e illustrate another embodiment of the device 10, this time configured to replace a typical dispersion screen or shower screen of an espresso coffee machine. The device 10 is fitted to the group head 60, which may be a common e61 group head.

A cylindrical housing 38 is provided and which is received against seal 40 so that the device 10 can be installed in the same manner as a conventional dispersion screen. The device 10 is partially received within the cylindrical housing 38 and free to move upwardly and downwardly during use with seal 24 sealing against cylindrical housing 38.

Figure 5f illustrates another embodiment for other espresso machines which retain the shower screening using a group head distributor screw 46, showing an extra component in the way of a retainer structure 58 having an outer diameter larger than an inner indent portion on the cylindrical housing 38 and a screw hole through which group head distributor screw 46 holds the retainer structure in place, and the said retainer 58 larger outer diameter retaining the cylindrical housing 38 in place. This retainer 58 can be formed of a pervious plate section and/or a flat spring length and/or even a bent wire section.

Figure 5g shows yet another embodiment for retaining the housing 38 where the housing 38 is now constructed with an upside-down cup like shape and having a perforated top structure and with a screw hole for a retaining screw 46 to retain the housing structure 38.

A pressure release may be provided to allow venting of water under pressure if the device 10 moves too far down within the housing, this allows flushing of the device 10 without the structure falling out under pressure. Different versions of pressure releases are shown in Figures 5a to 5g. Figure 5a show a version where grooves are formed in an upper portion of seal 24 (see Figure 6). Alternatively, a permeable ring 42 (Figure 5b) may be provided on the upper portions of the seal 24. Figures 5c to 5g illustrate a further alternative where slots are formed on the ends of the cylindrical housing 38 (see Figure 7).

In the embodiments of Figures 5a and 5b, the pressure release activates as the device 10 is forced downwardly by water in the pressurisable space 44 to its furthest travel whereupon seal 24 is compressed by an inner flared edge on the end of the cylinder 38. Eventually, the bottom sealing surface of the seal 38 is lifted and broken, allowing water to pass. A spring could also be installed between top inner surface of the group head 30 and the upper shell 12 of the device 10 to push the device 10 down to a non-sealed resting state allowing for the open fast draining of space 44 when not in use (not shown in figures). In embodiments 5c to 5g, the pressure release activates as device 10 moves down the housing 38 and seal 24 is compromised by the slots integrated at the end of the housing 38 which allows water to pass.

By way of illustration Figure 5d also shows an elastomeric non-return valve 66 installed between the upper disk 32 and the upper shell 12 under the aperture 16 which can be used on any of the devices. Non-return valve 66 can also have an embedded small protective metal plate partly covering its top centre portion to protect it against the jet of high-pressure water coming from aperture 16 (not shown).

The thinness of the device 10 illustrated in Figure 1 to 5 allows for a slight skewing of the device inside the basket 28. Previously proposed devices did not allow for such behaviour. If skewing was not possible and the device 10 was confined to a near perfectly level and horizontal configuration, as in below described devices 110 (without any means to skew) or 210 (with a very rigid and dense internal supported structure 126 and hence no ability to flex), then a puck that was not tamped level by the barista would be compressed excessively on one side. This would lead to an imbalance in flow in the lower density side of the puck, resulting in less than ideal extraction, and the compressive force applied by a device would exacerbate the imbalance. This is because the puck water resistance scales exponentially with the packing fraction of the coffee ground. This effect would mandate that coffee grounds are very carefully distributed and tamped evenly and/or the device would be limited to lower diameter portafilters applications such as 54mm or 50mm where due to the extra puck thickness, perfect distribution is less critical, and/or would require an alternative means to even out the compressive force.

However, it is now further realized that baristas in busy cafes may not even at all distribute coffee grounds after grinding and before tamping. This means that there can be present not just a skew distribution in grounds but random density fluctuations throughout the area of the puck, necessitating a compressive piston device that has the ability to conform its surface to the puck's potentially uneven density/height fluctuations so as to place a more even compression force on the puck's surface.

Figures 8a and 8b illustrate a device 110 configured for distributing water onto a mass of coffee grounds compacted in a collection basket 128 according to another embodiment of the invention. Device 110 is specifically configured to be incorporated into the head of a coffee machine which is adapted for such use.

With this embodiment, like features from device 10 have been identified using reference numerals incremented by 100.

Device 110 is received in group head cylinder 160 and is free for vertical movement or reciprocation therein. The device 110 has an upper shell component 112 with at least one constrictive aperture 116 formed therein, and a lower shell component 114 which is configured to urge against the coffee grounds or puck 150.

Between shells 112, 114 a space 120 is formed and in which water collects during use. At an upper end of space 120, distribution discs 132 and 134 are provided, being constructed in accordance with discs 32, 34 described above, though it will be appreciated that one or both of these distribution discs may be omitted and the mode of water distribution replaced with a water misting nozzle connected to constriction 116 that sprays an even mist of water into space 120 and onto the lowest section of the lower shell 14 (not shown in the figures).

In Figure 8a the device 110 is in an unpressurised state and Figure 8b illustrates the device 110 in a pressurised state. Water flows from the coffee machine through aperture 148 and into pressurisable space 144 before flowing through constriction 116.

As space 144 pressurises and water flows through constriction 116, the device 110, having pressure on its upper surface is urged downwardly and against the coffee grounds or puck 150. One or more return springs 156 are provided to assist in return and/or retainment of the device 110 after use, though it will be appreciated that any number of springs could also be used, or indeed no springs need be used at all, and instead drain features described in device 10 such as the slots cut in the cylinder housing 38 can be applied with groove cut on ends of the inner wall of the group head 146, such that as the seal 152 moves down in contact with said grooves the seal is broken and pressure is released and the system drains.

The device 110 is generally cylindrical in shape and it will be appreciated that it is more elongate than device 10. In a side wall of the device 110, seal 152 is provided, which act to maintain pressure within space 144 to facilitate movement of the device 110.

As with device 10, device 110 which is urged against the puck 150 to impart pressure against the coffee grounds and distribute water generally evenly over the grounds. By imparting pressure against the puck 150, device 110 acts as the above-described top layer, compacting the top layer to ensure effective flow of water through the top layer coffee particle's internal molecular structures, providing for better extraction of these particles as well as providing for the ability to manipulate the puck's 150 resistance to water. In a preferred embodiment, the opening 116 is configured to promote 1 to 12 bars of pressure against the upper shell component 112 during a steady state water flow rate of 1.33mL/s, as required to produce proper espresso timings. To ensure that the device 110 can withstand such pressure, device 110 may be provided with an internal support structure to prevent internal collapse.

Figures 9a to 9c show optional features which can be used in place of or in line with constriction 16, 116, 216 of the device 10, 110 or 210 to change the flow/pressure characteristics of said device where we see a nut adapter 62 configured to be installed in the upper shell component 12, 112, 212. In this case, the upper shell component 12, 112, 212 has a matching inner screw thread. Nut 62 has at least one through hole 64 to allow for water passage, and in the embodiment of Figure 9a also has a needle 66, which is gradually inserted into the constrictive aperture 16 so that the flow rate and hence compressive back pressure force on an upper shell component 12, 112, 212 can be altered by the user by screwing in the nut 62. Figure 9b shows a second means to allow for the user adjustment of the compressive back-pressure force, via a set of replaceable nuts 62, with different size through hole(s) 64 that act like the constrictive aperture(s) 16, 116, 216. Hence the user will change out the nut 62 to change the overall average compressive backpressure force said device can apply at any particular flow rate. Figure 9c also shows another alternative where the nut 62 has installed a constant flow valve, being an elastomeric doughnut-shaped o-ring 68 installed inside a slopped cone shape hollow hole in the nut 62. However, it will be appreciated that elastomeric inserts with different cross- sectional structures can be used. Further nuts 62 with different constant flow valve ratings can be exchanged by the user by unscrewing the nut 62 and replacing it with a different nut 62, which has a different flow/pressure characteristic o-ring 68 installed. In Figures 9a to 9c, the nut 62 may also have an outer slit to engage a flat-head screwdriver at the top (not shown in cross-sectional figures) so that it can be unscrewed by the user. Alternatively, a handle attachment can be provided and attached to the nut 62 so as to provide the grip needed to unscrew the nut 62 without a tool. For automated systems, where the espresso machine monitors the flow rate and/or espresso liquid weight and "on the fly" compares and adjusts the back-pressure to obtain a desired flow profile, the needle valve shown in 9a can also be motorised and hence adjusted by the espresso machine during extraction. In such cases, a tethered flexible line will need to be connected to the nut to apply the required torque; this would be best implemented in the embodiment shown in Figure 8 through the top part of the group head 130 (not shown).

By way of schematic illustration Figure 10 shows the many different flow characteristics that could be achieved using different flow constricting valves that are known in the art of valve construction and can be integrated into nut 62 to be used for any of the devices described herein. Of particular interest to our application is the flow reduction with pressure valve. Such a valve can be constructed by simply modifying the shore hardness of the o-ring used in Figure 9c and/or perhaps increasing the slope of the cone shape hollow hole in which it sits. A flow reduction valve in series with a small constriction is of particular interest since when installed in upper shell component 12, 112 or 212, it allows for the easy manipulation of the coffee puck's resistance to water flow via "on the fly" changes to pressure within space 44, 144 or 244 in the respective devices, without needing to implement a mechanical means to change the flow characteristic of the valve.

An espresso machine or a manual espresso machine user can now monitor flow rate and if the grind is too coarse can increase pressure in space 44, 144 or 244 which compacts the coffee puck and slows the flow allowing for proper extraction as discussed. Conversely, finer grounds require less time and pressure to extract properly, and if the user or espresso machine detects a large resistance to flow they can decrease pressure in space 44, 144 or 244, which in turn increases flow allowing for proper espresso timings.

Figures 11a to lid illustrate a device 210 configured for distributing water onto a mass of coffee grounds compacted in a collection basket 228 according to another embodiment of the invention. Device 210 is specifically configured to be incorporated into the head of a coffee machine which is adapted for such use.

With this embodiment, like features from devices 10, 110 have been identified using like reference numerals incremented by 200 or 100 respectively. Device 210 is received by group head cylinder 260 and is free for vertical movement or reciprocation with respect thereto and is formed with an upwardly extending cylindrical portion 254 which is received in a correspondingly elongated shaped section of the group head 260. The cylindrical portion of Figure 11a is larger than that of Figure lib, and as such embodiment 11a will exert a reduced pressure force on the upper part of the device when compartment 244 is pressurised.

The device 210 has an upper shell component 212 with at least one aperture 216 formed therein, and a lower shell component 214 which is configured to urge against the coffee grounds or puck 250.

Between shells 212, 214 a space 220 is formed and in which water collects and distributes during use. At an upper end of space 220, distribution discs 232 and 234 are provided, being constructed in accordance with discs 32, 34 described above, though it will be appreciated that these distribution discs may be omitted.

As described above, water flows from the coffee machine through aperture 248 and into pressurisable space 244 before flowing through constriction 216.

As space 244 pressurises and water flows through constriction 216, the device 210 is urged downwardly and against the puck 250. A single return spring 256 may be provided to assist in return of the device 210 after use.

Again, seals 252 are provided in a side wall of the device 210. Seals 252 act to maintain pressure within space 244 and to facilitate movement of the device 210.

The device of Figures 11c and lid differs from that of Figures 11a and lib in that pressure to drive the device 210 downwardly is introduced to a second independent chamber 270 around the top of the upper shell component 212 and water for brewing is introduced by aperture 248, into chamber 244, said two chambers 270 and 244 are not in fluid communication inside the group head 230, and hence their pressures independently controllable. In these embodiments there is an open aperture water entry port 276 in an upper portion of shell 212 connected to a "main pump", however this aperture 276 is not constrictive as in devises 10 or 110 which have apertures 16 or 116 respectively. It will be appreciated that independent control of pressure and water flow in chambers 270 and 244 may require two sources of pumped fluid. Figure 11c shows a "secondary pump" which can, in this case, also be a simple air pump. Although it should be appreciated that space 270 can be pressurised using various other means not necessarily involving a pump. Figure lid, show an alternative arrangement for controlling pressure and water flow into chamber 244 and 270 independently, where flow from a main pump flows into chamber 244 via said port 248 and unconstricted aperture 276, but is also diverted into chamber 270 via an electronically controlled 3-way diverter as shown. This flow can also be shunted via a 2- way diverter into a drain line for accurate pressure control in chamber 270.

It will be appreciated that many arrangements involving pumps, pistons, 2 and/or 3 way diverters, shunts, pressure gauges, and many other means could be used to independently control both pressure and flow into chambers 244 and 270 and hence in manipulating and controlling, extraction and expresso timings.

As with devices 10, 110 device 210 is urged against the puck 250 to impart pressure against the coffee grounds and distribute water generally evenly over the grounds. By imparting pressure against the puck 250, device 210 acts as the above-described top layer, compacting the top layer particles of the puck to ensure effective flow of water through the top layer coffee particle's internal molecular structure and to provide for the ability to manipulate the puck resistance during the extraction. In a preferred embodiment, the chamber 270 is independently and variably pressurised to provide 1 to 12 bars of pressure force against the upper shell component 212 depending on the measured flow characteristics of the puck and hence espresso timings. To ensure that the device 210 can withstand such pressure, device 210 may be provided with an internal support structure to prevent internal collapse. Figures 12a and 12b illustrate a device 310 configured for distributing water onto a mass of coffee grounds compacted in a collection basket 328 according to another embodiment of the invention. Device 310 is specifically configured to be incorporated into the head of a coffee machine which is adapted for such use.

With this embodiment, like features from devices 10, 110 and 210 have been identified using like reference numerals incremented by multiples of 300, 200 or 100, respectively.

Device 310 is received by group head cylinder 360 and is free for vertical movement or reciprocation with respect thereto. Unlike device 110 which is received in a group head cylinder of which is quite wide, device 310 is formed with a narrower upwardly extending cylindrical portion 354 which is received in a correspondingly shaped section of the group head 360.

The device 310 has a lower shell component 314, and an upper shell component 312 which is different to the above embodiments in that it has at least one non-constrictive aperture 376 formed therein.

Between shells 312, 314 a cavity 320 is formed and in which water collects during use. At an upper end of space 320, the device shown in Figure 12a has provided perforated distribution discs 332 and 334, being constructed in accordance with discs 32, 34 described above, while the device shown in Figure 12b only has one distribution disk disc 332, although it will be appreciated that these distribution discs may be omitted. In the device shown in Figure 12b, shell 312 is formed of two components, the first being a narrower upwardly extending cylindrical portion 354, the second being a perforated section and the two connected using ball and socket joint integrally formed in each corresponding component. The action of the ball and socket 380 is to relieve any lateral stress on the narrow component if the user distributes the coffee puck 350 in an uneven manner, the lower portion of the shell 312 can conform to the uneven puck 350 during extraction. Such a ball and socket arrangement 380 can be optionally used in other embodiments. As described above in relation to the embodiments of figure 1 to 5, the action of the ball and socket 380 allows for a slight skew to the device inside the basket 28. Device 310 can therefore accommodate a puck that was not tamped level by the barista and which would otherwise be compressed excessively on one side, leading to an imbalance in flow in the lower density side of the puck and less than ideal extraction, and the compressive force applied by a device would exacerbate the imbalance.

As described above, water flows from the coffee machine through aperture 348 and into device 310. Unlike the above-described embodiments, pressure on the puck 350 is provided by an external force imparted on the device 310 via an external actuator 378 acting on the cylindrical portion 354 which is independently controlled and used to manipulate the compressive force on the puck 350 and hence flow rate through the puck 350 during extraction. It will be appreciated that the external actuator may take many forms and be provided by mechanical, electromagnetic, gravitational or centrifugal force means.

As water flows into device 310, the device 310 is urged downwardly and against the puck 350 slowing the flow of coffee as required. As with all other devices, the variable strength of this compression force may be controlled electronically to result in a user set flow profile and/or a user set espresso ratio after a user set extraction time, i.e., specific espresso timings. A single return spring 356 may be provided to assist in return of the device 310 after use.

Again, seals 352 are provided in a side wall of the device 310. Seals 352 act to maintain pressure within the device and to facilitate movement of the device 310. Note, the device shown in Figure 12a has non-pressurised space 370 and hence does not require a group head seal.

Figure 13 shows various examples of collector basket 38 base configurations that can be used with any of the above-described devices. Figure 13a shows a standard portafilter basket structure with a removable fine filter paper disk 18 placed on top of the standard perforated base. Figure 13b shows a portafilter basket structure made in one piece with a base having two times or so more holes than a traditional portafilter basket, said hole count forming the actions of a fine filter disk 18. Figure 13c shows a collector basket 38 manufactured in two separate pieces and then welded together, the first is the cylindrical portion of the collector basket 38 and the second is the base portion with sides that are bent upwards that are welding to the ends of the cylindrical portion.

Figure 14a and 14b show an upper and lower perspective exploded view of a device, and Figure 14c, showing a cross section of the same device, where the pervious lower shell component 14 is moulded and incorporated into the underside of a perforated disk 34, and where the topside of the perforated disk contains all the distribution channels 36. The device has removable replaceable nut adapters 62 which can be exchanged to provide different flow constrictions 64, and is held in place via hold down structures moulded into the shell component 12. In this embodiment a contact deflector disc 22 is incorporated as a bottom structure in the adapter nuts 62.

Upper shell component 12 and perforated disc 34 may be complimentary in shape, with interengaging features 70 to allow the parts to lock together. This may simplify assembly.

In this embodiment the upper shell is formed of a semi-flexible material with the advantage that the seal 24 (with a flap that makes it self-energizing) can be incorporated into the outer edge of the upper shell.

To facilitate removal, device 10 is preferably formed with features such as pull tabs 72 that allow the user to pull the device out of the basket. Alternatively, a set of radially spaced top structures with undercuts 74 can be moulded into the top portion of the upper shell, such that a matching radial tool (not shown) can be inserted into the basket and twisted to engage said undercuts 74 to retain the tool to the device 10, so as to allow the hot device to be removed from the basket without touching it (tool not shown). The device 10 may incorporate a pre-filter 76 prior to the constriction to prevent clogging. The pre-filter may be incorporated into the upper shell component 12 or be a separate part, or incorporated into the adapter nuts 62 as shown in the embodiment.

Summary of puck resistance manipulation means

It is instructive to outline and summarise the main extraction method and back pressure force generation means proposed for each described device.

For manual lever espresso machines, the removable device 10 allows the user to use different constrictions 16 (and flow vs pressure valves) and during extraction observe the espresso flow and press the lever harder if an excessive flow is detected; the resultant extra pressure on shell 12 forces device 10 to compress the puck and constrict the espresso flow to recover proper espresso timings.

For electric espresso machines, the removable and/or retrofittable device 10 allows the machine to monitor the espresso flow and increase pump pressure if an excessive flow is detected; the resultant extra pressure on shell 12 forces device 10 to compress the puck and constricts the espresso flow to recover proper espresso timings.

For electric espresso machines, the integrated device 110 allows the machine to monitor the espresso flow and increase pump pressure if an excessive flow is detected; the extra pressure on shell 120 forces device 110 to compress the puck and constrict the flow to recover proper espresso timings.

For electric espresso machines, the integrated device 210 (shown in Figure 11a and lib), allows the machine to monitor the espresso flow and increase pump pressure if an excessive flow is detected; the extra pressure on shell 212 forces device 210 to compress the puck and constrict the flow to recover proper espresso timings.

For electric espresso machines, the integrated device 210 (shown in Figure 11c and lid), allows the machine to monitor the espresso flow and to independently increase the pressure in chamber 270 and/or slow the flow into chamber 244, if an excessive flow is detected; the extra pressure on shell 212 forces device 210 to compress the puck and constrict the flow to recover proper espresso timings.

For electric espresso machines, the integrated device 310, allows the machine to monitor the espresso flow and if an excessive flow is detected increases the actuated force on device 310 to compress the puck and constrict the flow to recover proper espresso timings.

In all instances, an opposite, i.e., a reduction in compressive force on the puck can be implemented if the opposite is observed or detected, that is: an insufficient espresso flow rate. In this way, the proposed device allows espresso machines to utilise a much wider range of grinder settings, which largely eliminates the need to "dial in" a coffee bean.

It will be appreciated that while the above discusses monitoring the outlet espresso flow for the purposes of variably compressing and hence manipulating the puck's resistance to water flow and hence changing expresso timings, this same objective can also be accomplished by monitoring the water flow rate into the basket, hence monitoring flow rates and/or the cumulative liquid amount that has flown into the basket is also within the scope of the invention.

It will also be appreciated that for device embodiments where a pressure gauge and port could easily be provided in the top section of the upwardly extending cylindrical portion 254, such as the devices 210 shown in Figures 11a and b (port not shown in Figures) or for the devices 210 shown in Figure 11c and d, and devices 310 where inlet ports 248 and 348 respectively, could be used to monitor the device's cavity 220 or 320 pressure, we need not directly monitor any flow rates to manipulate espresso timings, instead, for example, we can use a set predetermined water flow profile into the device (for some user- specified dose, preferably corresponding to ideal expresso timings) and instead an algorithm can monitor the pressure inside the device's cavity 220 or 320, and if some excess or deficit in pressure is detected, the espresso machine can adjust the compressive force applied to the puck to bring the pressure back to a predetermined pressure profile curve. This method has the advantage in that it does not require any flow meters or weight scales.

It will also be appreciated that while the above discusses monitoring pressures and flow rates to adjust espresso shot timings using variable compressive forces applied via the device during the espresso shot, such information can also be used to make adjustments to espresso shot timings using the device for any subsequent espresso shots, where for example the espresso machine can remember the last espresso shot timings, and use that information to adjust the compressive force the device applies to the puck to obtain an espresso shot timing closer to a user-specified time in subsequent shots.

It has been found that the preferred magnitude of the back-pressure compressive force as a function of time during the extraction, termed here as the compressive force profile, is a profile that in general, increased the compressive force on the puck throughout the shot (not necessarily in a linear fashion), starting with a relatively low compressive force during pre-infusion. The magnitude of the compressive force is, of course, dependent on the desired espresso timings. The reason for an increasing compressive force profile is that an ever-larger compressive force is required toward the end of the shot to restrict the ever-larger water channels that develop throughout the shot in between the coffee particles as solubles and fines are evacuated from the puck. This is, of course, only possible for devices where the water pressure at the puck and compressive force applied by the piston can be independently controlled.

However, it has also been found that even prior to pre-infusion, a large starting compressive back-pressure force can be applied momentarily to the puck during the initial filling phase of the device and spaces 220 or 320, and can be of benefit in ensuring an even wetting of the puck's surface, since the compressive force prevents water from soaking too quickly into the puck, and especially running down the sides of the basket before water fully floods the top surface of the puck. Once spaces 220 or 320 are filled sufficiently, the compressive force is then released, the puck expands, pulling an even layer of water into its interior and pre-infusion starts proper.

Many modifications of the above embodiments will be apparent to those skilled in the art without departing from the scope of the present invention.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

In describing the invention, it will be understood that a number of techniques, means, structures, features, processes, and steps are disclosed. Each of these has individual benefits, and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques, means, structures, features, processes, and or steps. Accordingly, for the sake of brevity, this description will refrain from repeating every single possible combination of the individual said techniques, means, structures, processes, and steps in an unnecessary fashion. Nevertheless, the specification should be read with the understanding that such combinations are entirely within the scope of the invention.

Claims

CLAIMS:

1. A device for distributing water onto and compressing a mass of coffee grounds compacted in a collection basket, the device configured to be at least partially received in the collection basket and formed of a shell having an upper shell component with at least one opening through which pressurised water flows from a coffee machine and a water pervious lower shell component for contacting the mass of coffee grounds, the shells defining at least one cavity therebetween in which water can flow, wherein within the shell there is formed a constriction in a path of pressurised water flow so that in use the device is urged against the coffee grounds by water pressure pressing on the shell as a means to transfer and impart a linear force against the coffee grounds and distribute water generally evenly over the grounds.

2. A device according to claim 1, further including means within the at least one cavity to disperse water radially outwardly from the at least one opening around the at least one cavity.

3. A device according to claim 1 or claim 2, further including a water pervious support structure within the at least one cavity to prevent collapse of the upper or lower shells.

4. A device according to any preceding claim, further including a seal extending around a periphery of the device to seal the device within the collection basket or within an upper group head chamber to create a pressurised space above the upper shell of the device.

5. A device according to any preceding claim, wherein the upper shell component is formed of multiple layers each having perforations formed therein and at least one of which has water distribution channels formed therein to distribute water within the at least one cavity.

6. A device according to any preceding claim, wherein the constriction path is formed in the upper shell component.

7. A device according to any preceding claim, wherein one or more shell or disk components are flexible and configured to conform to the surface of the mass of coffee grounds.

8. A device according to any preceding claim, wherein the device is free to skew within the collection basket to accommodate surface height and/or density variations in the mass of coffee grounds.

9. A device according to any preceding claim, configured to be received against a group head of an espresso machine, wherein the shell is at least partially retained within a housing secured to the head and is free for vertical movement to bear against the coffee grounds, the device including a seal extending around a periphery of the shell to seal the shell within the housing secured.

10. A device according to claim 9, further including a retainer having an outer dimension larger than an inner indented portion on the housing and one or more fastener holes through which one or more said fasteners holds the said retainer in place, and the said retainer larger outer dimension holding the housing in place.

11. A device according to claim 9, further including at least one retraction spring between the head of the espresso machine and the shell to retract and/or retain the shell after use.

12. A device according to claim 9, further including a pressure releasing means so that the device is not forced out of the secured housing during flushing of a group head, if there is no basket and compressed coffee grounds secured inside the espresso machine group.

13. A device according to any preceding claim, further including an upwardly extending guide in association with the upper shell component for restricting movement of the shell to a generally vertical axis.

14. A device according to any preceding claim, further including an integrated nonreturn valve on each of the at least one opening present on the upper shell component of the device, and/or a needle flow adjustment valve, and/or a constant flow valve, and/or a removable nut with one or more integrated constrictions, and/or a reduced flow with greater pressure valve.

15. A method of making coffee, comprising the steps of: providing a device according to any preceding claim; providing pressurised, heated water into the opening in the upper shell; and collecting coffee flowing from the basket.

16. A coffee machine, comprising: a device for distributing water onto and compressing a mass of coffee grounds compacted in a collection basket, the device configured to be at least partially received in the collection basket and formed of a shell having an upper shell component with at least one opening through which water flows from the coffee machine and a perforated lower shell component for contacting the mass of coffee grounds, the shells defining at least one cavity therebetween in which water can collect; and means for imparting reciprocal movement to the device to urge it against the coffee grounds to impart a linear compressive force thereto and distribute water generally evenly over the grounds.

17. A coffee machine according to claim 16, wherein said means includes a secondary and independently adjustable source of pressurised fluid introduced into the space above the device.

18. A coffee machine according to claim 16, wherein said means includes a linear actuator for displacing the shell.

19. A method of making coffee, comprising the steps of: providing a coffee machine according to any one of claims 15 to 17; providing pressurised, heated water into the opening in the upper shell; applying a compressive force to the device to maintain pressure against the coffee grounds; and collecting coffee flowing from the basket.

20. A method according to either claim 15 or claim 19, further including the step of monitoring the water pressure inside the at least one cavity, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds and varying the compressive force exerted onto the surface of the mass of coffee grounds to achieve a water pressure, and/or a flow rate, and/or a cumulative liquid amount within a predetermined range.

21. A method according to claim 20 where the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is approximated by monitoring the water flow rate flowing to the mass of coffee grounds, and/or the cumulative water amount that has flowed to the mass of coffee grounds using a flow meter.

22. A method according to claim 20 where the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is approximated by monitoring the coffee flow rate from the basket, and/or the cumulative coffee amount that has flowed from the basket using a weight scale.

23. A method of making coffee, comprising the steps of: providing a mass of coffee grounds in a collection basket; applying a compressive force to the grounds during extraction with a perforated device through which water can flow; flowing heated water through the device so that the water flows through the grounds under pressure to brew coffee; and collecting the coffee, wherein the water pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is monitored and the compressive force applied to the grounds by the device varied to keep the water pressure, and/or flow rate, and/or the cumulative liquid amount within a predetermined range.

24. A method according to claim 23 where the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is approximated by monitoring the water flow rate flowing to the mass of coffee grounds, and/or the cumulative water amount that has flowed to the mass of coffee grounds using a flow meter.

25. A method according to claim 23 where the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds is approximated by monitoring the coffee flow rate from the basket, and/or the cumulative coffee amount that has flowed from the basket using a weight scale.

26. A method according to claim 23, wherein a compressive force is applied to the grounds via a variable force actuator.

27. A method according to any one of claims 21 to 26, wherein a computational algorithm that monitors and calculates the amount of compressive force applied to the mass of coffee grounds by the device during extraction involves comparing the device's internal pressure, and/or the liquid flow rate that is flowing through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds, to a predetermined pressure profile curve, and/or a flow rate profile curve, and/or a cumulative liquid amount profile curve at multiple time points during the extraction, and if the pressure, and/or the liquid flow rate, and/or the cumulative liquid amount is found to deviate by some amount then some stepped change in compressive force is applied to the mass of coffee grounds.

28. A method according to claim 27 wherein the said some stepped change in compressive force applied to the mass of coffee grounds by the device for any said deviation from said curve(s) is determined through a self-learning algorithm calculated over multiple extractions.

29. A method according to either claim 16 or claim 20 or claim 23 wherein the coffee machine remembers the pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds at some time point during the extraction and uses that information in subsequent extractions to adjust the compressive force applied to the mass of coffee grounds by the device so that some predetermined pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds can be obtained at some time point during the extraction.

30. A method according to claim 29 wherein the adjusted compressive force applied to the mass of coffee grounds by the device for some said subsequent extraction is determined through a self-learning algorithm which uses one or more past extractions to determine a relationship between the compressive force applied to the mass of coffee grounds and the pressure, and/or the liquid flow rate through the mass of coffee grounds, and/or the cumulative liquid amount that has flowed through the mass of coffee grounds at some time point during the extraction.

31. A method according to any one of claims 19 to 30, wherein the extraction involves a substantially increasing compressive force applied to the mass of coffee grounds throughout the majority of the extraction.