EP1802223A2

EP1802223A2 - Boiler for an automatic machine for producing a coffee-based drink

Info

Publication number: EP1802223A2
Application number: EP06723140A
Authority: EP
Inventors: Giuseppe De' Longhi
Original assignee: De Longhi SpA
Current assignee: De Longhi SpA
Priority date: 2005-11-11
Filing date: 2006-02-28
Publication date: 2007-07-04
Also published as: WO2006077172A3; ITMI20052151A1; DE06723140T1; WO2006077172A2

Abstract

The boiler (5) for an automatic machine (1) for producing a coffee- based drink comprises a plate-shaped heating body (6) having a perimetric channel (7) for the passage of the brewing water to be heated and a central space (8) suitable for housing a flexible tube (9) for hydraulic connection between the boiler (5) and a closure piston (3) of the brewing chamber (4) of the brewing group of the coffee machine .

Description

BOILER FOR AN AUTOMATIC MACHINE FOR PRODUCING A COFFEE-BASED DRINK

DESCRIPTION

The present invention refers to a boiler for an automatic machine for producing a coffee-based drink, and to the automatic machine that uses such a boiler .

As known, automatic coffee machines comprise a brewing group defining a brewing chamber suitable for being closed by a closure piston through which the water is fed to the brewing chamber for brewing .

The closure piston can be fixed directly to the boiler that produces the hot water for brewing, as shown for example in patent documents EP 0937432 , EP 0931491 and IT01295378.

In this case the closure piston and the boiler constitute a simple assembly.

This on the one hand avoids the complication of having to make suitable hydraulic connections between the closure piston and the boiler, and on the other hand limits the path of the brewing water between the boiler and the brewing chamber and therefore its cooling along such a path.

However, this suffers from the drawback of a difficult dislocation of the assembly formed by the boiler and by the closure piston with respect to the specific morphology of the machine .

In a different type of automatic coffee machine the closure piston and the boiler are physically separated parts hydraulically connected by a flexible tube .

In this case, the greater ease of dislocation of the individual parts with respect to the morphology of the machine is opposed by the drawback of a longer path of the brewing water from the boiler to the brewing chamber and therefore its greater cooling in the case of long time periods between one operating cycle of the machine and the next .

The structure of a known boiler for an automatic coffee machine generally foreseen an aluminium heating body formed from two juxtaposed plates with the interposition of a perimetric sealing gasket .

On the interfacing surfaces of the two plates half- impressions are made that , when juxtaposed, overall define a spiral-shaped channel in which the brewing water to be heated flows .

An electrical resistance with curvilinear progression suitable for heating the heating body is positioned on the outer surface of one of the plates .

Such a boiler suffers from various drawbacks .

The efficiency of the heat exchange can be penalised by the provision, configuration and arrangement of the single resistance foreseen as well as by the amount and distribution of the mass of the heating body. In particular, a poor efficiency means a lengthening of the time to reach the desired temperature for the preparation of the drink and/or a greater presence of water in the steam, when the boiler operates to produce steam instead of hot water .

The sealing gasket is positioned inside the heating body in an environment subj ected to repeated temperature gradients and to high operating temperatures that in the long term can damage it and cause undesired leaks .

Moreover, if the processing of the two plates is not sufficiently precise, the seal between the half-impressions in contact may not be perfect so that the brewing water can leak and bypass a part of the heating path inside the boiler .

This causes a possible oscillation of the temperature of the brewing water, from one operating cycle of the machine to the next .

The aluminium-based material constituting the heating body, which comes into direct contact with water for drinking, can have tough limitations of use so as to respect the increasingly stringent regulations regarding food .

Moreover, such a material on the one hand is particularly exposed to the deposit of limestone and on the other hand has little resistance to the chemical action of decalcifying agents .

The technical task proposed of the present invention is , therefore, that of making a boiler for an automatic machine for producing a coffee-based drink and a coffee machine that uses such a boiler that allow the aforementioned technical drawbacks of the prior art to be eliminated .

In this technical task, a purpose of the invention is to make a boiler for an automatic machine for producing a coffee- based drink and a coffee machine that uses such a boiler that , for each operating cycle of the machine , allow the brewing cycle to be fed with brewing water having the desired temperature .

Another purpose of the invention is to make a boiler for an automatic machine for producing a coffee-based drink and a coffee machine that allow the boiler and the closure piston of. the brewing chamber to be easily moved inside the machine without for this reason having to undergo a cooling of the brewing water present in the journey from the boiler to the brewing chamber, also in the presence of a significant idle time of the machine between one operating cycle and the next .

Yet another purpose of the present invention is that of making a boiler for an automatic machine for producing a coffee-based drink having optimised efficiency so as to reduce the time to reach the desired temperature for the brewing water, and to produce a dryer steam when the boiler operates to produce steam.

Yet another purpose of the present invention is that of making a boiler for an automatic machine for producing a coffee-based drink capable of achieving a greater constancy of temperature of the brewing water between one operating cycle and the next .

Yet another purpose of the present invention is that of making a boiler for an automatic machine for producing a coffee-based drink that is extremely reliable and durable over time .

The last but not least purpose of the invention is to make a boiler for an automatic machine for producing a coffee-based drink in which the parts in contact with the brewing water are suitable for use with water for drinking, prevent limestone from being deposited and are resistant to the use of decalcifying agents .

The technical task, as well as these and other purposes , according to the present invention, are accomplished by making a boiler for an automatic machine for producing a coffee-based drink according to claim 1.

Other characteristics of the present invention are defined, moreover, in the subsequent claims .

Further characteristics and advantages of the invention shall become clearer from the description of a preferred but not exclusive embodiment of the boiler for an automatic coffee machine according to the finding, illustrated for indicating and not limiting purposes in the attached drawings , in which : figure 1 shows a perspective view of a boiler according to a preferred embodiment of the invention; figure 2 is a perspective view of the shaped tube of the boiler of figure 1 ; and figure 3 is a top side section view of the boiler of figure 1 , in which the coffee machine and the positioning of the boiler with respect to the cup- heating plane are schematised.

With reference to the quoted figures , an automatic coffee machine is schematically shown schematically indicated with reference numeral 1.

The coffee machine 1 has a brewing group comprising the brewing cylinder 2 (schematised with a broken line) mobile with respect to a closure piston 3 between an open position and a closed position of a brewing chamber 4 suitable for containing the dose of coffee powder through which the brewing water percolates for the preparation of the drink.

The machine 1 also has a boiler 5 selectively suitable for heating the brewing water or for producing steam.

The boiler 5 comprises a plate-shaped heating body 6 having a perimetric passage channel 7 of the brewing water to be heated and a central space 8 suitable for housing a flexible tube 9 for the hydraulic connection of the boiler 5 and the closure piston 3.

The channel 7 has an inlet 20 on the outer side perimeter of the heating body 6 and an outlet 10 that faces the space 8.

The space 8 constitutes a heating chamber of the flexible tube 9 and of the brewing water contained in it . The space 8 preferably extends through the entire thickness of the heating body 6 and opens on a vast central area of the heating body 6.

The presence of the space 8 results in a reduction in mass of the heating body 6 and consequently increases the speed with which the heating body 6 reaches the desired operating temperature .

The boiler 5 has electrical heating means 12 of the heating body 6 , comprising a first and at least a second electrical resistance 13 and 14 arranged in respective housing seats 15 and 16 consisting of impressions of matching shape present on the opposite main faces of the heating body 6.

The boiler 5 is preferably arranged horizontally with one of the main faces of the heating body 6 facing the cup-heating plane 51 of the machine 1 that is thus advantageously heated: the heating of the cup-heating plane 51 also takes place by direct exposure to the electrical resistance 13.

The first and second electrical resistance 13 and 14 overall circumscribe the space 8 and are in turn circumscribed by the perimetric channel 7 that advantageously extends helically around the space 8.

The first and second electrical resistance 13 and 14 each have a substantially squashed half-ring shape and are mutually arranged so as to define and overall squashed ring shape matching the shape of the space 8 on one side and matching the shape of the channel 7 on the other . Advantageously, the heating body 6 is a monoblock.

The channel 7 is covered by a shaped tube 17 at least partially incorporated in said monoblock.

The shaped tube 17 is advantageously made from a material highly compatible with drinking water, and in particular is made from stainless steel , whereas the heating body 6 is preferably still made from aluminium-based material .

In detail , the shaped tube 17 has an inlet end 18 that extends outside the inlet 20 of the channel 7 and an outlet end 19 that extends outside the outlet of the channel 7.

The heating body 6 does not have sealing gaskets inside it .

A respective first and second sealing gasket 21 and 22 are indeed fitted onto the inlet end 18 and outlet end 19 , respectively, of the shaped tube 17.

The first gasket 21 acts for the sealed connection, through connector 24 , between the tube 17 and the supply duct 23 of water from the tap or from a suitable container, whereas the second gasket 22 acts for the sealed connection, through connector 25 , between the tube 17 and the flexible tube 9.

Each connector 24 , 25 has a tubular body 27 , 28 from the bases of which the parts to be connected can be introduced; such a tubular body 27 , 28 has openings 29 , 30 for the introduction of transversal locking clips (not shown) on its side surface, near to its opposite ends .

The clips are suitable for interfering with portions 31 , 32 having modified diameter of the parts introduced in the tubular body 27 , 28 so as to prevent it from slipping .

The heating body 6 carries an associated plated spacing and screening structure 35 , at a main face thereof , suitable for supporting the closure piston 3.

The spacing and screening structure 35 has the purpose of taking the closure piston 3 a suitable distance from the heating body 6 and screening it from the heating body 6 and in particular from the electrical resistance 14.

This is mainly because the present application does not require the heating body 6 to influence the temperature of the closure piston 3 that is indeed preferably made from plastic that can deteriorate if subj ected to a high temperature .

The plated structure 35 has, in an area that faces the space 8 , holes 36 and 37 passing through the connection of the flexible tube 9 to the closure piston 3.

The closure piston 3 has a stem 38 carrying a flange 39 at the base held firmly between a first and a second plate 40 and 41 of the plated structure 35.

In particular, the plates 40 and 41 are j oined together through screws , and the larger plate 40 is in turn j oined through screws to a main face of the heating body 6.

The stem 38 has an axial channel 42 inside which the male connection end 44 of a tubular connector 45 is locked through sealing gaskets 43 , said connector having an opposite female connection end 46 that holds an end of the flexible tube 9.

The female connection end 46 is structurally and functionally equivalent to the one shown previously with reference to the connectors 24 and 25.

The tubular connector 45 has, in the space defined by the two plates 40 and 41 , some side protrusions 47 that wedge between the flange 39 and the plate 41 to hold the tubular connector 45 in position.

A shutter 48 is made to close the connection end 44 in contrast to and by the action of a spring 49 resting on an inner shoulder 50 of the channel 42.

The operation of the boiler according to the invention is clear from what has been described and illustrated and, in particular, is substantially the following .

When an operating cycle of the machine begins , the electrical resistances 14 and 15 are activated that heat the heating body 6.

The heating body 6 in turn begins to heat the channel 7 and simultaneously the heating chamber consisting of the space 8.

Consequently, both the water present in the channel 7 and the water present in the flexible tube 9 arranged in the space 8 are simultaneously heated.

When the pressure force of the water on the shutter 48 exceeds the action applied by the spring 49 , the shutter moves opening the passage of the brewing water towards the brewing chamber 4 through the closure piston 3.

It should be noted that the provision of the flexible tube 9 for the hydraulic connection between the boiler 5 and the closure piston 3 not only avoids having to carry out extremely precise and therefore expensive processing to ensure the correct seal between the two parts, but also allows a certain degree of freedom in the choice of the relative arrangement between the boiler 5 and the closure piston 3 , thus simplifying the rearrangement of the assembly with respect to the morphology of the machine 1 , and all of this without the drawback of the cooling of the water present in the flexible tube 9 thanks to the positioning of the latter in the space 8.

The provision of a monoblock heating body 6 allows the temperature of the brewing water to be kept constant from one operating cycle to the next , due to the fact that the brewing water cannot bypass the inner channel 7 of the heating body 6.

The reliability of the boiler 5 is substantial , given that the sealing gaskets do not deteriorate : the heating body 6 does not have sealing gaskets inside it , where, in use , higher temperatures are reached, but on the outside and to be precise at the ends of the shaped tube 17 where in use significantly lower temperatures are reached.

The heat exchange of the boiler 5 is optimised both due to the specific amount and distribution of its mass and due to the fact that two electrical resistances are used, one of which, moreover, carries out the heating of the cup-heating plane 51 to which it is directly exposed in an extremely efficient manner, in combination with the heating body 6.

The optimisation of the heat exchange allows the time needed to reach the desired temperature for the brewing water to be reduced, and, if necessary, allows a drier steam to be produced.

The material of the shaped tube 17 that covers the channel 7 respects the most stringent regulations regarding food, limits limestone deposits and resists the chemical aggression of decalcifiers well .

The boiler thus conceived can undergo numerous modifications and variants , all covered by the inventive concept ; moreover, all of the details can be replaced by technically equivalent elements .

In practice, the materials used, as well as the sizes , can be whatever according to the requirements and the state of the art .

Claims

1. Boiler for an automatic machine for producing a coffee- based drink, characterised in that it comprises a plate- shaped heating body having a perimetric channel for the passage of the brewing water to be heated and a central space suitable for housing a flexible tube for hydraulic connection between said boiler and a closure piston of the brewing chamber of the brewing group of said coffee machine .

2. Boiler according to claim 1 , characterised in that said space constitutes a heating chamber of said flexible tube and of the brewing water possibly contained in it .

3. Boiler according to one or more of the previous claims , characterised in that said channel has an inlet on the outer side perimeter of said heating body and an outlet that faces said central space .

4. Boiler according to one or more of the previous claims , characterised in that said central space extends through the entire thickness of said heating body.

5. Boiler according to one or more of the previous claims, characterised in that it has electrical heating means of said heating body, comprising a first and at least a second electrical resistance .

6. Boiler according to one or more of the previous claims , characterised in that said first and second electrical resistance are arranged in respective housing seats consisting of impressions of a matching shape present on the opposite main faces of said heating body.

7. Boiler according to' one or more of the previous claims , characterised in that said first and second electrical resistance overall circumscribe said central space and are in turn circumscribed by said perimetric channel .

8. Boiler according to one or more of the previous claims , characterised in that said perimetric channel extends helically around said central space .

9. Boiler according to one or more of the previous claims, characterised in that said first and second electrical resistance are each substantially squashed half-ring shaped and are mutually arranged so as to define an overall squashed ring shape matching the shape of said space on one side and matching the shape of said channel on the other .

10. Boiler according to one or more of the previous claims , characterised in that said heating body is a monoblock.

11. Boiler according to one or more of the previous claims, characterised in that said channel is covered by a shaped tube at least partially incorporated in said monoblock.

12. Boiler according to one or more of the previous claims , characterised in that said shaped tube is made from a material highly compatible with drinking water .

13. Boiler according to one or more of the previous claims , characterised in that said shaped tube is made from stainless steel .

14. Boiler according to one or more of the previous claims , characterised in that said heating body is made from aluminium-based material .

15. Boiler according to one or more of the previous claims , characterised in that said shaped tube has an inlet end that extends outside said inlet of said channel and an outlet end that extends outside said outlet end of said channel .

16. Boiler according to one or more of the previous claims , characterised in that it has a respective first and second sealing gasket fitted on said inlet end and said outlet end, respectively, of said shaped tube .

17. Boiler according to one or more of the previous claims , characterised in that said monoblock carries an associated plated structure , at a heating face thereof, suitable for supporting said closure piston in a position distant and screened from said heating body and from said electrical resistances .

18. Boiler according to one or more of the previous claims , characterised in that said plated structure, in an area that faces said space, has through holes for the connection of said flexible tube to said closure piston.

19. Boiler according to one or more of the previous claims , characterised in that it has connectors of said inlet end and outlet end, respectively, of said shaped tube to a water tap and to said flexible tube, respectively, each of said connectors having a tubular body at the bases of which the parts to be connected can be introduced, said tubular body having openings for the introduction of transversal locking clips on its side surface, close to its opposite ends .

20. Automatic machine for producing a coffee-based drink, characterised in that it comprises a boiler in accordance with one or more of the previous claims .

21. Machine according to the previous claim, characterised in that said boiler is arranged horizontally with one of said main faces of said heating body facing the cup-heating plane of said machine .

22. Boiler for an automatic machine for producing a coffee- based drink as described and claimed.