Disassemblable double-walled filter for coffee machine with tightening element

A filter for a coffee machine comprises a cup-shaped body (2) for containing coffee powder, having at least a bottom wall (3) having an opening (5); a filtering wall (6) placed in the cup-shaped body (2) upstream of the opening (5) and removably associated with the cup-shaped body (2); a seal (7) placed at least between one edge (6b) of the filtering wall (6) and the cup-shaped body (2); a tightening member (8) active on the filtering wall (6) and on the seal (7) so as to reversibly fix said filtering wall (6) and said seal (7) to the cup-shaped body (2); said tightening member (8) comprising a tubular element (9) connected to the filtering wall (6) and to the seal (7) and arranged through the opening (5); said tubular element (9) being directly constrained to the cup-shaped body (2) by means of a bayonet-type connection.

CROSS-REFERENCE TO RELATED APPLICATIONS

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THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

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BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention concerns a filter for a coffee machine. In particular, the present invention can be applied in the so-called double-walled filters.

In fact, filters are known comprising a cup-shaped body having a bottom wall and a substantially cylindrical lateral wall connected to the bottom wall. A compartment is defined in the cup-shaped body for the coffee powder.

The filter is intended to be inserted in a filter holder that is coupled to the coffee machine for making the beverage. An opening is provided in the bottom wall for the infused coffee to exit.

A filtering wall is arranged within the cup-shaped body compartment. The filtering wall is substantially flat and has a multitude of through holes that allow the infused coffee to pass and retain the coffee powder in the compartment. A seal may be placed between the filtering wall and the cup-shaped body to prevent the coffee powder passing into the gap and through the exit opening.

Known filters further comprise a coupling member necessary for coupling the filtering wall and the cup-shaped seal. The coupling member comprises a plate fixed to the seal and to the filtering wall and a tubular element as a single piece with the plate and coaxial thereto and inserted in the aforementioned exit opening. A threaded locking ring is constrained to the tubular element by means of threading. The locking ring prevents the tubular element sliding through the opening and therefore keeps the filtering wall, the seal and the plate tightened to one another.

Within the tubular element an outlet channel is defined for the infused beverage. A flow regulation valve is placed within the tubular element. Such valve is also useful for defining the throttling that accelerates the flow of the beverage at the exit so as to create a coffee cream. Such filters are also known for example from document WO_02/091889_A2.

Filters of the known type described have some drawbacks. They are, above all, complex to construct and assemble due to the large number of elements of which they are composed. Furthermore, filters of the known type are difficult to clean. In fact, when a cleaning operation is necessary, they must be disassembled into all the components, cleaned and then reassembled. Still due to the high number of components, this operation is long and inconvenient.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to propose a filter for a coffee machine that avoids the described drawbacks. In particular, it is an object of the present invention to propose a filter for a coffee machine that is simple and convenient to clean. Furthermore, it is a further object of the present invention to propose a filter for a coffee machine that is simple to construct.

The objects of the present invention are reached by a filter for coffee machines comprising the characteristics of one or more of the appended claims. According to the present invention, a filter for a coffee machine comprises a cup-shaped body for containing coffee powder, having at least a bottom wall which has an opening; a filtering wall placed in the cup-shaped body upstream of the opening and removably associated with the cup-shaped body; a seal placed at least between one edge of the filtering wall and the cup-shaped body; a tightening member active on the filtering wall and on the seal so as to reversibly fix said filtering wall and said seal to the cup-shaped body; the tightening member comprises a tubular element connected to the filtering wall and to the seal and arranged through the opening; the tubular element is directly constrained to the cup-shaped body by means of a bayonet-type connection.

This solution allows the filtering wall and the seal to be assembled and disassembled extremely quickly and simply form the cup-shaped body. When it is necessary to proceed with the cleaning of the filter, the step of separating all its components is therefore made extremely simpler and quicker.

This advantage is firstly appreciated in the domestic environment, but is particularly useful in the professional environment where cleaning operations imply machine downtime that is naturally undesirable. Furthermore, it is to be noted that the bayonet-type connection implies construction simplification with a reduction in the number of elements constituting the filter. By way of example, in the solution described, no fixing ring to be associated with the tubular element is necessary.

According to a further aspect of the present invention, the bottom wall has at least a through slot and the tubular element comprises at least one tongue that can be inserted into the slot for making the bayonet-type connection. Preferably, the bottom wall has two slots and the tubular element comprises two tongues; each tongue can be inserted in a corresponding slot for making the bayonet-type connection. This solution enables the bayonet-type connection to be made effectively and reliably.

According to a further aspect of the present invention, the slots are arranged in diametrically opposite positions relative to a centre of the bottom wall; the tongues are arranged in diametrically opposite positions relative to a central axis of symmetry of the tubular element. This solution enables a balanced and symmetrical distribution of the necessary forces for guaranteeing the connection. In this situation, the tightening member does not suffer excessive strain, preventing any damage that can compromise the reliability of the filter.

According to a further aspect of the present invention, the tightening member comprises a disk fixed to the tubular element coaxially thereto and associated with the filtering wall and with the seal. This characteristic allows the tightening member to be simply connected to the seal and to the filtering wall. In fact, these are the components that must be tightened by the tightening member.

According to a further aspect of the present invention, the disk has a dispensing hole to permit a beverage coming from the filtering wall to exit. The hole has a diameter comprised between 0.3 mm and 0.5 mm and preferably is substantially equal to 0.4 mm.

It is to be observed that the term “dispensing hole” here means a passage of small dimensions and such as to determine a notable acceleration of the flow of beverage in transit. Such acceleration is also at the origin of the high flow turbulence which causes a marked mixing of air with the consequent formation of a coffee cream or froth.

A person skilled in the art will realise that the presence of such dispensing hole makes the presence of flow regulation valves superfluous, at least with reference to the production of the coffee cream. The absence of valves determines a notable construction simplification of the filter according to the present invention. Furthermore, it is clear that, following the simplification in the construction of the filter and in particular following the further reduction in the number of components, the cleaning of the filter becomes even simpler.

According to a further aspect of the present invention, the dispensing hole faces the tubular element. This allows the space defined within the tubular element to be used for making the flow of beverage flow out of the dispensing hole.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the appended figures, a filter for coffee machines according to the present invention is indicated in its entirety by the number1. The filter1comprises a cup-shaped body2having a bottom wall3and a lateral wall4fixed to the bottom wall3. In the cup-shaped body2a compartment is therefore defined for containing a pre-determined dose of coffee powder. As shown, the cup-shaped body2has an axisymmetric shape and is made of metal material. The cup-shaped body2is, in use, intended to be inserted in a filter holder of a coffee machine.

In the bottom wall3of the cup-shaped body2an opening5is made which allows the beverage to exit the filter1in the way that will appear clear below. The opening5has a circular shape.

The filter1further comprises a filtering wall6, arranged within the cup-shaped body2and placed upstream of the opening5. The filtering wall6comprises a flat portion6a, having a multitude of through holes through which the infused beverage passes, retaining the particles of coffee powder.

It is to be observed here that the flat shape of the portion6aof the filtering wall is not a limiting characteristic and may be substituted by a convex or concave curved shape or any other shape.

The filtering wall6further comprises an edge6bthat extends perimetrally to the flat portion6a. The filtering wall6is removably associated with the cup-shaped body2. In more detail, the filtering wall is arranged in the cup-shaped body2so that the edge6bis coupled to the cup-shaped body2. In particular, the edge6bis preferably coupled to the lateral wall4. The filtering wall6is in general made of metal material, but other materials such as plastic are just as possible.

The filter1further comprises a seal7placed between the filtering wall6and the cup-shaped body2. In more detail, the seal is placed at least between the edge6bof the filtering wall6and the cup-shaped body2. Such seal7prevents a flow between the filtering wall6and the cup-shaped body2which would also cause the passage of coffee powder which would contaminate the beverage.

It is to be noted that in the step of making the beverage, the filter1is crossed by a flow of hot water under pressure. The water flow pressure can reach a value of 9-10 bar. The seal7is therefore made so as to withstand such pressure. In this example, in a non-limiting way, the seal7is made of elastomeric material, for example, silicone rubber.

The filter1further comprises a tightening member8active at least on the filtering wall6and on the seal7to fix such elements in a removable way to the cup-shaped body2. The tightening member8allows a simple and quick coupling and uncoupling of the filtering wall6and the seal7from the cup-shaped body2. Advantageously, this allows the cleaning steps of such pieces and therefore of the entire filter1to be made quicker and simpler.

The tightening member8comprises a tubular element9removably fixed (in the way that will be clear in the present description below) to the filtering wall6and to the seal7. The tubular element9is further arranged through the opening5and coaxially thereto. The tubular element9has a circular shaped section.

In accordance with the present invention, the tubular element9is directly constrained to the cup-shaped body2through a bayonet-type connection. In the embodiment shown in the figures, in detail inFIG. 3, the tubular element9comprises two tongues10that extend radially from the tubular element9itself. The tongues10are coplanar to one another. More precisely, the tongues10lie on a substantially orthogonal plane to a central axis of symmetry of the tubular element9. The tongues10are arranged in diametrically opposite positions with respect to the central axis of symmetry of the tubular element9.

Furthermore, the bottom wall3of the cup-shaped body2has two through slots11. The slots11are arranged diametrically opposite the centre of the bottom wall3. The slots11are substantially counter-shaped to the tongues10.

In fact, in a step of coupling the tightening member8with the cup-shaped body2, each tongue10is inserted into a respective slot11in order to cross the bottom wall3. By rotating the tubular element9, in the example depicted inFIG. 3by 90°, the tongues10are no longer at the slots11and the tubular element9is not further separable from the bottom wall3. In this way, the bayonet-type connection mentioned above is made.

The tightening member8further comprises a disk12fixed coaxially to the tubular element9. The disk12is further connected to the filtering wall6and to the seal7for connecting them to the tightening member8. In more detail, the disk12and the tubular element9are made as a single piece. The disk12and the tubular element9are made of plastic material. The disk12has a circular shape and is coupled to the filtering wall6. The diameter of the filtering wall6is substantially equal to the diameter of the disk12. The disk12is alongside, in contact and superimposed on the filtering wall6.

The disk12further comprises spacer elements13that allow the definition of a gap14between the disk12and the filtering wall6. In other words, the disk12is in contact with the filtering wall6through the spacer elements13. The spacer elements13comprise a peripheral ring13athat rises from the edge of the disk12. Furthermore, the spacer elements13comprise protrusions13bthat extend from a central portion of the disk12.

The shape, position and number of spacer elements13are in no way limiting characteristics. In fact, the disk12may have any number of such elements and of any shape.

The filtering wall6and the disk12are removably inserted in a seat15afforded perimetrally in the seal7. In this way, the filtering wall6, the seal7and the disk12are solidly but reversably joined. In other words, the filtering wall6and the seal7are connected to the tightening member8through the disk12.

The disk12has a through dispensing hole16which allows a beverage coming from the filtering wall6to exit. The dispensing hole16is placed in a central and coaxial position to the disk12itself and to the tubular element9. The dispensing hole16therefore faces the tubular element9and opens into it.

The dispensing hole16has a portion with a constant diameter and a flared portion. In detail, the flared portion faces the filtering wall6. The diameter of the dispensing hole16, at least in its constant diameter portion, is comprised between 0.3 mm and 0.5 mm. In the embodiment described and illustrated, such diameter is 0.4 mm. Such diameter allows a sensitive acceleration of the beverage flow to allow the creation of coffee cream. The invention thus described reaches the pre-set objects. In fact, thanks to the bayonet coupling which connects the cup-shaped body and the filtering wall to one another, it is particularly quick and convenient to disassemble the filter into all its components for being able to clean them. In fact, it is only necessary to promote a rotation of the tightening member, aligning the tongues with the slots, for proceeding with the disassembly.

Furthermore, the absence of further tightening elements (like, for example, the threaded locking ring) limits the number of filter components, simplifying its construction. Naturally, the cleaning is also simplified following the reduction in components.