TECHNICAL FIELD

The present invention relates to a beverage-making infusion unit.

More specifically, the present invention relates to an infusion unit for making a beverage from a measure of anhydrous powdered material in a container; the container comprising a package with a central portion and a peripheral portion; the unit comprising a percolating cup for housing the container, and a pressurized-hot-water dispensing unit comprising a supporting body, and a sprinkler fitted to the supporting body and having an axis; and the cup and sprinkler being movable with respect to each other between a parted position, and a fluidtight connected position in which they define a percolating chamber.

BACKGROUND ART

In an infusion unit of the above type, the beverage is normally made by loading a fresh container into the cup in the parted position; infusing and dispensing the beverage, with the cup and sprinkler in the connected position; and, finally, unloading the used container from the cup. The container is unloaded after the cup and sprinkler return to the parted position, and may be unloaded either manually, by the user removing it from the cup, or automatically, by means of an unloading device for expelling the container from the cup, e.g. by tilting the cup. However it is done, the used container can therefore only be unloaded if it remains inside the cup when the cup and sprinkler return to the parted position at the end of the infusion stage.

In actual fact, however, this is extremely difficult to ensure when using containers in the form of a 'wafer', i.e. a package made of filter paper, with a circular outer flange. In which case, the soaked paper of the used wafer very often causes the wafer to stick to the sprinkler when the cup and sprinkler are parted, thus making it impossible to remove automatically, or difficult and dangerous to remove manually.

A common solution to the above problem is to fit the bottom of the sprinkler with an elastic member, which is compressed against the sprinkler by the wafer when the cup and sprinkler move into the connected position, and relaxes when the cup and sprinkler are parted, thus detaching the wafer from the sprinkler and keeping it inside the cup.

The elastic member normally comprises a straightforward coil spring, or a plate fitted elastically through the bottom wall of the sprinkler, or a movable central portion of the bottom wall of the sprinkler, as described, for example, in EP-A-1152678 , EP-A-1477092, and WO2006/126230.

In actual use, all the above solutions have a common drawback : given the fragile nature of the paper when the wafer is soaked, the pressure exerted by the elastic member on the centre of the wafer to detach it from the sprinkler tends to tear the paper, especially when fine paper is used, thus resulting in failure to detach the wafer, and fallout of the powdered material contained inside it.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an infusion unit of the above type, designed to provide an effective, straightforward, low-cost solution to the above drawback.

According to the present invention, there is provided a beverage-making infusion unit as claimed in Claim 1 and preferably in any one of the Claims depending directly or indirectly on Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which Figures 1 and 2 show axial sections, with parts removed for clarity, of a preferred embodiment of the infusion unit according to the present invention in respective operating configurations .

BEST MODE FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 indicates as a whole an infusion unit for making a beverage from a measure of anhydrous powdered material, e.g. ground coffee, inside a container 2 defined, in the example shown, by a known wafer made of filter paper and having a package 3 comprising two opposite, flat, circular central portions 3a, a circular outer flange 4, and an annular peripheral portion 3b connecting central portions 3a to flange 4.

Unit 1 comprises a frame, in turn comprising a bottom portion 5 fitted with a percolating cup 6 for housing container 2, and a top portion (not shown) supporting a pressurized-hot-water dispensing unit 7.

More specifically, dispensing unit 7 comprises a hydraulic cylinder 8 with a vertical axis 9, and in turn comprising a tube 10, and a piston 11 mounted inside tube 10 to slide, along axis 9 and in opposition to elastic return means (not shown) , from a withdrawn rest position (Figure 1) to an extracted work position (Figure 2) .

Close to its axial end facing a bottom wall of tube 10, piston 11 has an annular flange, which extends radially up to tube 10, and defines, between piston 11 and the bottom wall of tube 10, a variable-volume chamber 12 sealed fluidtight by a seal 13, and which, in use, is fed with pressurized water by a conduit (not shown) .

At its opposite axial end, piston 11 has an end portion, which projects axially from tube 10 and defines a supporting body 14 for a sprinkler 15, which is supplied with pressurized hot water from a boiler (not shown) by a conduit 16 formed in supporting body 14 and communicating with sprinkler 15 via a one-way valve 17 calibrated to open when conduit 16 reaches a given pressure .

Sprinkler 15 is substantially cup-shaped, and is divided into a central portion and a peripheral portion connected to each other telescopically.

More specifically, the central portion is defined by a circular plate 18, which is integral with supporting body 14, is bounded laterally by a cylindrical surface 20 coaxial with axis 9, and has an outside diameter approximating but no larger than the diameter of central portion 3a of package 3. Plate 18 is secured rigidly by screws to an end surface 19 of supporting body 14 crosswise to axis 9, and has, on the side facing supporting body 14, a number of appendixes 21 parallel to axis 9 and inserted, with the interposition of respective seals, inside respective cavities in supporting body 14.

On the side facing cup 6, plate 18 has a truncated- cone-shaped cavity 22 flaring towards cup 6, coaxial with axis 9, and fitted with a perforated filter plate 23, which covers the top of cavity 22 and separates cavity 22 from a water supply conduit 24 formed in plate 18, coaxially with axis 9, and communicating with conduit 16 via valve 17.

The peripheral portion of sprinkler 15 is defined by a tubular body 25, which has a centre hole 26 coaxial with axis 9, is bounded on the side facing supporting body 14 by a flat surface 27 parallel to surface 19, and is bounded on the side facing cup 6 by a flat surface 28 parallel to surface 27. Starting from surface 27, hole 26 comprises a cylindrical portion 26a connected slidably to cylindrical surface 20 of plate 18; and a flared portion 26b, which is equal in depth to roughly half the thickness of container 2, and has a major diameter roughly equal to the maximum diameter of package 3. Both cylindrical portion 26a and flared portion 26b are surrounded by respective annular cavities formed in respective surfaces 27 and 28 and housing respective sealing rings.

As shown in Figures 1 and 2, tubular body 25 is fitted to supporting body 14 to move, with respect to supporting body 14 and plate 18 and along axis 9, between a normal extracted position (Figure 1) , in which tubular body 25 is detached from supporting body 14 and almost completely detached from plate 18, and a withdrawn position (Figure 2), in which surface 27 of tubular body 25 mates with surface 19 of supporting body 14, and plate 18 is inserted inside hole 26 through cylindrical portion 26a and part of flared portion 26b.

To permit the above movement, tubular body 25 is fitted to supporting body 14 by two pins 29, which are integral with tubular body 25, are parallel to axis 9, are located on opposite sides of axis 9, and slide axially inside respective holes 30 formed in supporting body 14.

On the side facing tubular body 25, each hole 30 has a wider portion defining a seat for a respective coil spring 31, which is coiled about respective pin 29 and compressed between supporting body 14 and surface 27 of tubular body 25 to normally keep tubular body 25 in the extracted position (Figure 1) .

Pins 29 (which, in a variation not shown, may be more than two in number and equally spaced about axis 9) have an axial retainer (not shown) for preventing them from withdrawing completely from holes 30 when tubular body 25 is pushed into the extracted position by springs 31.

As shown in Figure 1, cup 6 is defined by a cup- shaped body bounded, on the side facing sprinkler 15, by a flat surface 32 crosswise to axis 9 and having a central semiellipsoidal cavity 33, which is aligned with hole 26 along axis 9, is equal in depth to roughly half the thickness of container 2, and has a maximum diameter approximating but no smaller than the maximum diameter of peripheral portion 3b of package 3.

As explained in more detail below, cavity 33 defines a bottom infusion half-chamber , which mates in fluidtight manner, with the interposition of flange 4, with a top half-chamber defined inside hole 26 by plate 18 and tubular body 25 to form a fluidtight chamber, in which to percolate the beverage, and from which the beverage flows out.

For this purpose, the bottom wall of cavity 33 is fitted by a screw 35 with a filter plate 34, which separates cavity 33 from a discharge channel 36 formed in an axial appendix of cup 6 and communicating with the outside .

Operation of unit will now be described as of the Figure 1 configuration, in which piston 11 is in the withdrawn position, sprinkler 15 and cup 6 are parted, and spring 31 holds tubular body 25 in the extracted position.

After a fresh container 2 is inserted into cavity 33 of cup 6, hydraulic cylinder 8 is operated to extract piston 11 and move sprinkler 15 towards cup 6. Before piston 11 reaches the fully extracted position, tubular body 25 impacts surface 32 of cup 6 and is pushed, by the movement of piston 11 and in opposition to springs 31, towards supporting body 14.

In the withdrawn position, tubular body 25 is pressed in fluidtight manner by piston 11 against supporting body 14 on one side, and, on the other side, against cup 6, which is thus connected to sprinkler 15 to form the percolating chamber (Figure 2), to which pressurized hot water can now be fed along conduit 16 and via one-way valve 17. As shown clearly in Figure 2, in this connected configuration, plate 18 presses on central portion 3a of package 3, tubular body 25 presses on peripheral portion 3b, and flange 4 is gripped in fluidtight manner between surfaces 28 and 32.

Once infusion is completed and the beverage dispensed, hydraulic cylinder 8 is deactivated, and piston 11 is pushed by the elastic return means (not shown) back into the withdrawn position.

As soon as piston 11 starts to withdraw, plate 18 detaches immediately from central portion 3a, and springs 31 detach tubular body 25 from supporting body 14, and keep it pressed against cup 6 and peripheral portion 3b, which thus remains inside cavity 33.

When tubular body 25 reaches the extracted position and can no longer move with respect to supporting body 14, withdrawal of piston 11 detaches tubular body 25 from cup 6 and restores sprinkler 15 to the parted position (Figure 1) .

Unit 1 thus ensures the used container 2 detaches effectively, and with no tearing, from sprinkler 15, and remains inside cup 6, from which it can then be removed. This is achieved, firstly, by forming sprinkler 15 in two telescopically connected portions, to reduce sticking of the soaked paper to sprinkler 15; and, secondly, by exerting as little detachment pressure as possible on central portion 3a, which, as is known, is the most fragile part of package 3, and the part most subject to tearing when package 3 is wet and the material inside is soaked and compacted. In other words, as sprinkler 15 detaches from cup 6, the used container 2 is held inside cup 6 by tubular body 25 pressing on peripheral portion 3b, which is thicker and stronger than central portion 3a, thus enabling central portion 3a to detach smoothly and safely from plate 18.