WO2005058110A1

WO2005058110A1 - Water compressed boiler for coffee machines

Info

Publication number: WO2005058110A1
Application number: PCT/EP2004/053249
Authority: WO
Inventors: Carlo Rosa; Alessandro Ostuni
Original assignee: Ariete S.P.A.
Priority date: 2003-12-18
Filing date: 2004-12-02
Publication date: 2005-06-30
Also published as: ITGE20030108A1; EP1696773A1

Abstract

Water compressed boiler for coffee machines, comprising: an upper body (1) and a lower body (11) connected in a sealed manner so as to define between them a chamber (44) containing a certain quantity of water; an electric heating resistance (3); and a filter holder (28) situated underneath this lower body (11) and housing a filter liner (30) containing coffee powder; this lower body (11) has, formed inside it, one or more holes (13, 14) through which the water is able to flow from this chamber (44) to said filter liner (30); inside this boiler the flow of the water through these holes (13, 14) is regulated by means of a supply valve (18) housed in a seat (17) formed in the lower body (11) of the boiler and said electric resistance (3) is housed on the upper body (1) of the boiler and in a raised position with respect to said supply valve (18) and said water through-flow holes (13, 14).

Description

10412/E

TITLE: Water compressed boiler for coffee machines

DESCRIPTION The present invention relates to a water compressed boiler for coffee machines. As is known, water compressed boilers for coffee machines comprise an upper body connected in a sealed manner to a lower body. A chamber containing a certain quantity of water useful for preparing limited amounts of coffee is formed between these upper and lower bodies. This boiler normally has, connected thereto, a flange for attaching a filter holder provided at the bottom with ducts for discharging a coffee infusion and at the top with a filter liner into which a certain quantity of coffee powder is introduced. The part in the region of the flange for attaching the filter holder of the boiler also comprises one or more through-flow holes for the water and is provided with suitable seats for housing electric heating means, such as an electric resistance. One of the main drawbacks of these water compressed boilers is precisely the lowered position of the electric resistance. This electric resistance in fact heats up considerably the water contained in the boiler to very high temperatures which often prove to be incompatible with the coffee powder contained in the lower filter liner. As a result it is not possible to obtain a coffee infusion with optimum properties. Moreover, again owing to the lowered position of the electric resistance, in the top part of the boiler, i.e. in the region of the upper body, the pressure and the temperature of the steam produced often prove to be inadequate. The object of the present invention is therefore to overcome the drawbacks of water compressed boilers for known coffee machines mentioned above and provide a water compressed boiler which functions at high pressures and temperatures of the steam produced inside it, together with relatively limited heating of the water compatible with the coffee powder contained in the filter liner, so as to obtain ultimately a coffee infusion with optimum properties. This object is achieved by the present invention by means of a water compressed boiler for coffee machines, comprising: an upper body and a lower body 10412/E

which are connected in a sealed manner so as to define between them a chamber containing a certain amount of water; an electric heating resistance; and a filter holder situated underneath this lower body and housing a filter liner containing coffee powder; this lower body has, formed inside it, one or more holes through which the water is able to flow from this chamber to said filter liner; characterized in that the flow of the water through these holes is regulated by means of a supply valve housed in a seat formed in the lower body of the boiler and this electric resistance is housed on the upper body of the boiler and in a raised position with respect to said supply valve and said water through-flow holes. Further objects and advantages of the present invention will emerge more clearly during the course of the following description, considered by way of a non- limiting example, with reference to the accompanying drawings in which: - Fig. 1 shows a side elevation and partially sectioned view of a coffee machine provided with a water compressed boiler according to a preferred embodiment of the present invention and comprising a hot-water supply valve; - Fig. 2 shows a partial side elevation and sectioned view of a zone of the coffee machine comprising the hot-water supply valve according to Fig. 1 in a closed position; - Fig. 3 shows a partial side elevation and sectioned view of a zone of the coffee machine comprising the hot-water supply valve according to Fig. 1 and Fig. 2 in an open position; - Fig. 4 shows a side elevation and partially sectioned view of a variation of embodiment of the boiler according to Fig. 1 , comprising an internal rubber membrane having a substantially frustoconical shape and an anti-unscrewing piston, in the inactive position, able to co-operate with a safety cap provided at the top of the coffee machine; and - Fig. 5 shows a side elevation and partially sectioned view of the boiler according to Fig. 3, in which the anti-unscrewing piston, in the active position, cooperates with said safety cap. With reference to the accompanying drawings and with particular reference to 10412/E

Fig. 1 thereof, 1 denotes the upper body of a water compressed boiler into which a certain quantity of water is introduced and which is provided at the top with a seat 2 housing an electric heating resistance 3. This electric resistance 3 could also be die- cast with the aluminium from which the boiler and therefore said upper body 1 is made. This upper body 1 comprises centrally a threaded hole 4 into which a corresponding safety cap 5 is screwed and, laterally, i.e. on the left viewing the figure, a steam supply duct 6. This duct 6 houses, inside it, a supply valve 7 provided with an obturator 8 having associated sealing means 9 and connected to a steam supply device 10. Below this upper body 1 the present water compressed boiler comprises a lower body 1 1 connected to said upper body 1 and provided with a seal 12. A chamber 44 containing a certain quantity of water is defined between this upper body 1 and lower body 1 1. A vertical wall of this lower body 1 1 , i.e. the right-hand wall 16 when viewing the figure, has formed in it a first substantially horizontal hole 13 connected to a second substantially vertical 14 formed in the base 15 of said lower body 11. In a position adjacent to said holes 13 and 14 and towards the outside of the water compressed boiler there is formed a seat 17 housing a valve 18 able to regulate the supply of water from the boiler and provided with a casing 19 housing a piston 20 sliding in the horizontal direction. Said holes 13 and 14 therefore form, respectively, the inlet hole and the outlet hole for the hot water into and from said supply valve 18. This piston 20 projects from the casing at both ends of said valve and is provided, at the end situated towards the boiler, with an obturator 21 which engages inside the hole 13 formed in the vertical wall 16 of the lower body 11 and, at the other end, has a rounded shape and makes contact with an actuating cam 22 connected to an operating lever 25. This actuating cam 22 is hinged by means of a pin 23 with a support 24 fixed inside the lower body 11 of the boiler externally and alongside said supply valve 18, while substantially at the height of the electric resistance 3 there is a projecting bracket 45 supporting a switch 26 activating said electric resistance 3. Said support bracket 45 in this case is fixed to the upper edge of the lower body 11 of the boiler and this switch 26, as we shall see below, interacts with said operating lever 25. A flange 27 for attaching a filter holder 28 10412/E

provided at the bottom with two coffee discharge ducts 29 is fixed underneath the lower body 11 of the boiler. Said filter holder 28 houses internally a filter liner 30 which is filled with coffee powder 34 and provided with an upper annular end 31 folded outwards so as to engage between the upper edge of said filter holder 28 and a seal 32 positioned below the base 15 of said lower body 11. A sprinkler base plate 33 is fixed, moreover, below said base 15 of the lower body 11 of the boiler. The upper body 1 of the boiler also has formed inside it an expansion chamber 46 inside which air or steam, but not water, may be present. This expansion chamber 46 acts as a pressure regulator, as we shall describe more fully below in connection with operation of the present boiler. With reference to Fig. 2 of the accompanying drawings, we shall consider in detail the various components of the hot-water supply valve 18. A first seal 34 is provided between the casing 19 of this valve 18 and the seat 17 in which it is housed, while a second seal 35 is positioned in the region of the obturator 21 of the hole 13 formed in the vertical wall 16 of the lower body 11 of the boiler. As mentioned before, the piston 20 emerges from both the ends of the casing 19 which comprises internally, as from the left-hand side viewing the figure, a cylindrical opening 36 for housing a frustoconical seal 37 which is fitted around the piston 20 and rests with its smaller-diameter base on a disk 41 formed around said piston 20. Said frustoconical seal 37 has a front cross-section greater than the seal 35 closing the through-hole 13 and therefore has its large-diameter base directed towards the outside of the valve 18 and therefore towards the mouth of said cylindrical opening 36. The annular seal 35 and the frustoconical seal 37 could alternatively be incorporated in a single seal: in this case the cylindrical part wound around the piston 20 of the frustoconical seal 37 would extend as far as the obturator 21 , lining it in the manner of a hood. A cylindrical seat 38 having a diameter smaller than said cylindrical opening 36 is formed, inside the casing 19 of the valve 18, adjacent to said cylindrical opening 36: the middle part of the piston 20, around which a recall spring 39 is fitted, slides inside said cylindrical seat 38. Adjacent to said cylindrical seat 38, finally, said casing 19 has internally an end through-hole 40 with a diameter smaller than that of said 10412/E

cylindrical seat 38. The ends of this recall spring 39 are then arranged between said disk 41 formed around the piston 20 and the step defined between the end of said cylindrical seat 38 and said end through-hole 40. The end of the piston 20 projecting from said end through-hole 40, as mentioned above, has a rounded shape and makes contact with the external surface of the actuating cam 22. This cam 22 has a tooth 42 able to strike against an end-of-travel stop 43 provided in the support 24. This end-of-travel stop 43 obviously must allow the operating lever 25 to pass from the position shown in Fig. 2 to the position shown in Fig. 3, and it is therefore possible to envisage, for example, that it is provided with a central slit of suitable thickness suitable for allowing the lever 25, but not the tooth 42 to pass through, whereby said tooth may have a width greater than that of said lever 42. Fig. 3 shows the supply valve 18 in the open position of the hole 13: as can be seen, the cam 22 has been rotated to the right, considering the figure, by means of the operating lever 25, so that the piston 20 has the possibility of being retracted towards the outside of said valve 18. The obturator 21 therefore frees the hole 13 which communicates with the hole 14, and the end-of-travel stop of the piston 20 is formed by the point where disk 41 strikes against the step defined between the cylindrical opening 36 and the smaller-diameter cylindrical seat 38 or, by way of an alternative and depending on given dimensional parameters of the valve 18, by the point where the rounded end of said piston 20 strikes against the cam 22, for strokes of the piston 20 less than the distance (see Fig. 2) between the disk 41 and said step defined between said cylindrical opening 36 and said cylindrical seat 38. With reference to Figs. 1 , 2 and 3 of the accompanying drawings, we shall now consider a first operating mode of the present water compressed boiler: firstly the safety cap 5 is unscrewed so as to allow access to the boiler and a quantity of water is inserted inside the chamber 44 defined between the upper body 1 and the lower body 11 , so as to fill the boiler up to the rim, said quantity being sufficient for example for two cups of coffee to be filled by means of the outlet ducts 29; the safety cap 5 is closed and the filter liner 30 is filled with coffee powder and then the filter holder 28 is inserted into the attachment flange 27. At this point the operating lever 10412/E

25 is rotated downwards, i.e. from the position shown in Fig. 2 into the position shown in Fig. 3, so that it trips the switch 26 of the electric resistance 3 which will therefore be activated. Lowering of the lever 25 causes rotation, towards the right, of the actuating cam 22 about the pin 23: as a result of this rotation said cam 22 is separated by a certain distance from the rounded end of the piston 20 and the latter is therefore free to move towards the outside of the valve 18 and the boiler. The electric resistance 3 starts to heat the boiler (upper body 1 and lower body 11 ) and the water introduced inside it. The particular position of the electric resistance 3 housed inside the seat 2 formed in the upper body 1 of said boiler is such that a layer of steam having a pressure increasing with time is formed. When the pressure inside the boiler, acting on the obturator 21 closing the hole 13 for entry of the hot water into the valve 18, overcomes the force of the spring 39, the piston 20 moves towards the outside of the boiler until it reaches the stop consisting, as mentioned, of the surface of the cam 22 or the disk 41 striking against the edge formed between the cylindrical opening 36 and the cylindrical seat 38 of the casing 19 of said valve 18. At this point the hole 13 for entry of the hot water into the valve 18 is connected to the hole 14 for discharging the hot water from said valve 18: since the piston 20 is displaced there could occur inside the boiler a reduction in the maximum pressure which would tend to cause said piston 20 to close again, moving again towards the boiler, owing to the thrust of the spring 39 which is compressed by the outwards movement of the piston 20. This problem of the return movement of the piston 20, which would produce closing again of the hot-water inlet hole 13, is avoided thanks to the frustoconical seal 37 which has a front cross-section much greater than the front cross-section of the seal 35 and has its larger-diameter base directed towards said seal 35. This use of the frustoconical seal 37 essentially results in two main advantages: the first one is that, even at low pressures, the piston 20 of the supply valve 18 remains open, allowing the hot water to pass through the holes 13 and 14, reach the sprinkler base plate 33 underneath the lower body 11 of the boiler and from here reach the filter liner 30 so as to act on the coffee powder contained therein; the second advantage is that the valve 18, at the desired pressure, opens completely, preventing obstruction 10412/E

of the hole 13 and causing a drop in pressure between said hole 13 for entry of the hot water into the valve 18 and the hole 14 for discharging the hot water. After supplying of hot water has started, when the user decides to stop said supply, he/she must rotate the operating lever 25 upwards again, i.e. into the closed position of the valve 18. This results in renewed contact between the actuating cam 22 and the rounded end of the piston 20 which is pushed into the closed position, i.e. with the obturator 21 inserted inside the hot-water inlet hole 13. As mentioned previously, the expansion chamber 46 has the function of a pressure regulator: when the water starts to evaporate, the pressurised steam causes compression of the air volume present in this zone; at the moment of opening of the supply valve 18, this compressed chamber 46 manages to maintain the pressure at high values, delaying any reduction thereof. Fig. 4 shows a first variation of embodiment of the present boiler in which the associated upper body 1 and the associated lower body 11 are shaped in a manner slightly different from that shown in Fig. 1. Said upper body 1 and said lower body have, packed between them, an internal membrane 47 made of rubber or other elastomer material, with a substantially frustoconical shape and having the function of supplying coffee at an optimum temperature and thermally isolating the metallic parts of said lower body 11 and said upper body 1. A high-temperature thermostat 48 (approx. 130^SC) is fixed to the upper body 1 of the boiler, while a low-temperature thermostat 49 (approx. 90⁸C) is fixed to the lower body 11. A compartment 50 housing an electric resistance 51 is also formed inside said lower body 11. The membrane 47 thermally divides the boiler into a high zone 44a and into a low zone 44b and the temperature of this high zone 44a does not influence the temperature of this low zone 44b. We shall now considerer how, with regard to the presence of this internal membrane 47 described in Fig. 4, operation of the water compressed boiler varies with respect to that described previously with reference to operation of the preferred embodiment of the invention shown in Fig. 1 : the high-temperature thermostat 48 controls the electric resistance 3 of the upper body 1 of the boiler, hence said 10412/E

resistance remains active until said upper body 1 reaches the threshold temperature of said thermostat 48. At this temperature, which may be in the region of 130°C, the water and steam zone 44a situated inside the chamber 44 above the membrane 47 is at a temperature much higher than those temperatures necessary for correct production of coffee and at an optimum pressure for said production. The electric resistance 51 of the lower body 11 is controlled by the low-temperature thermostat 49. Said electric resistance 51 remains switched on until said lower body 11 reaches the threshold temperature of said thermostat 49, for example 90^aC. At this temperature the water zone 44b situated inside the chamber 44 underneath the membrane 47 is at an optimum temperature for correct production of coffee. The pressure which is generated in the high zone 44a of the chamber 44 forces the water which is situated in the low zone 44b to pass through the coffee powder in the same manner as described above with reference to Figs. 1 , 2 and 3. Since the coffee powder is acted on by the water which is situated in the low part underneath said membrane 47, the result is that coffee with water at an optimum temperature is produced. A second variation of embodiment of the present water compressed boiler is the introduction of an anti-unscrewing piston 52 inserted into a guide seat 53 inside which a recall spring 54 wound around the piston 52 is inserted. This guide seat 53 is fixed to the upper body 1 of the boiler and is inserted inside the internal compartment 55 of the safety cap 5 so that the piston 52 housed inside it is aligned with one of a series of suitable holes 56 formed in said internal compartment 55 of said safety cap 5. This safety cap 5 also has a gripping knob 64 at the centre of which an insert 61 co-operating with a spring 62 is formed. The top of said guide seat 53 has a first through-hole 57 in alignment with a second through-hole 58 formed in the upper wall of the upper body 1 of the boiler. These through-holes 57 and 58 allow, as we shall see, vertical displacement of the anti-unscrewing piston 52 inside the associated guide seat 53. This piston 52 also has a washer 59 resting on the wall of said upper body 1 and is able to allow compression of the recall spring 54. An element 60 supporting a membrane 63 for actuating the anti-unscrewing piston 52 10412/E

is fixed inside the upper wall of said upper body 1. Said element 60 supporting the membrane 63 actuating the piston 52 keeps the edge of said membrane 63 integral with the upper body 1 of the boiler. Said piston 52 is pressed towards said membrane 63 by the recall spring 54. As a result of the guide seat 53, moreover, the piston 52 is kept along its vertical axis. The insert 61 of the safety cap 5 is integral with the body of said cap 5 and the knob 64 is formed so that it is constrained axially with said insert 61 and is free to rotate a few degrees relative thereto. In practice, when the knob 64 is rotated a few degrees, the insert 61 does not rotate; whereas, when the gripping knob 64 is rotated through several degrees, the insert 61 also rotates causing rotation of the body of the safety cap 5. This rotational play between said knob 64 and said insert 61 occurs in both directions of rotation, i.e. during screwing and unscrewing. In the rest condition, the knob 64 is situated in an intermediate equilibrium position with respect to the insert 61. We shall now consider operation of said anti-unscrewing piston 52 provided with an associated actuating membrane 63. When pressurised steam is formed inside the boiler, the membrane 63 actuating the piston 52 is compressed into the position shown in Fig. 5, resulting in a vertical upward movement of the piston 52 which is inserted inside the hole 56 formed inside the safety cap 5. Owing to this inserted arrangement, it is not possible to unscrew said safety cap 5. When the pressure falls below a given value, the membrane 63, owing to the effect of the return spring 54 of the piston 52, returns into the original position shown in Fig. 4, as does the piston 52, allowing rotation of the safety cap 5. The possibility of the gripping knob 64 being able to rotate freely a few degrees with respect to the insert 61 is such that, if the user attempts to unscrew the safety cap 5 when the piston 52 is engaged inside the associated hole 56, said piston does not seize up between said hole and the associated guide seat 53. If the seized condition were in fact to occur, the return spring 54 of the piston 52 would not be able to perform its function and therefore cause the piston to return into its original position shown in Fig. 4 when the pressure inside the boiler drops .

Claims

1. Water compressed boiler for coffee machines, comprising: an upper body (1) and a lower body (11) connected in a sealed manner so as to define between them a chamber (44) containing a certain quantity of water; an electric heating resistance (3); and a filter holder (28) situated underneath said lower body (11) and housing a filter liner (30) containing coffee powder, said lower body (1 1 ) having, formed inside it, one or more holes (13, 14) through which the water is able to flow from said chamber (44) to said filter liner (30), characterized in that the flow of the water through said holes (13, 14) is regulated by means of a supply valve (18) housed in a seat (17) formed in the lower body (1 1) of the boiler and said electric resistance (3) is housed on the upper body (1 ) of the boiler and in a raised position with respect to said supply valve (18) and said water through-flow holes (13, 14).

2. Water compressed boiler according to Claim 1 , characterized in that a first inlet hole (13) for allowing the water into said valve (18) is formed on a vertical wall (16) of said lower body (1 1 ) adjacent to the seat (17) housing the supply valve (18) and a second outlet hole (14) for discharging the water from said supply valve (18) is formed on the base of said lower body (1 1).

3. Water compressed boiler according to Claim 1 , characterized in that said supply valve (18) comprises a casing (19) housing a piston (20) projecting from both ends of said casing (19) and sliding therein, said piston (20) being provided, at the end directed towards the boiler, with an obturator (21) inserted inside first water inlet hole (13) and said piston (20) co-operating, at the other end, with means (22, 25) for effecting opening and closing of said supply valve (18).

4. Water compressed boiler according to Claim 3, characterized in that said obturator (21) comprises means (35) for closing in a hermetically sealed manner said inlet hole (13), at the other end of said casing (19), from which the obturator (21 ) of the piston (20) projects, there being formed a cylindrical opening (36) for housing a frustoconical seal (37) having a larger-diameter base with a cross-section greater than the front cross-section of said sealing means (35) and directed towards said obturator (21 ). 10412/E

5. Water compressed boiler according to Claim 3, characterized in that said operating means (22, 25) co-operate with a switch (26) for activating the electric resistance (3) housed on a support bracket (45) fixed outside the boiler.

6. Water compressed boiler according to Claim 3, characterized in that said operating means comprise a cam (22) hinged on a support (24) formed on the lower body (11) of the boiler outside the seat (17) housing the supply valve (18), the end of the piston (20) directed towards the outside of the boiler having a round shape so as to interact with said cam (22).

7. Water compressed boiler according to Claim 6, characterized in that said cam (22) is connected to an operating lever (25) which can be operated manually and has a length and an inclination such as to interact with the switch (26) for activating the electric resistance (3), positioned on said support bracket (45) situated at a height greater than that of the support (24) of said cam (22).

8. Water compressed boiler according to Claim 3, characterized in that said supply valve (18) comprises sealing means (34) positioned between the outer surface of said casing (19) and said housing seat (17).

9. Water compressed boiler according to Claim 4, characterized in that said casing (19) comprises internally a cylindrical seat (38) adjacent to said cylindrical opening (36) and having a diameter smaller than said opening, said piston (20) being provided with a disk (41) housed in said cylindrical opening (36) and the smaller-diameter base of said frustoconical seal (37) being positioned on the side of said disk (41) directed towards the boiler.

10. Water compressed boiler according to Claim 9, characterized in that said casing (19) comprises an end through-hole (40) formed at the end directed towards the outside of the boiler, said through-hole (40) having a smaller diameter than said cylindrical seat (38) and being able to allow the rounded end of the piston (20) to project.

11. Water compressed boiler according to Claim 9, characterized in that it comprises resilient recall means (39) which are fitted around the piston (20) and are positioned between the surface of said disk (41) directed towards the outside of the boiler and the step defined between said cylindrical seat (38) and the end through- hole (40).

12. Water compressed boiler according to Claim 6, characterized in that said cam (22) comprises a contact tooth (42) cooperating with an end-of-travel stop (43) formed in said support (24) positioned on the outside of said lower body (11) of the boiler.

13. Water compressed boiler according to any one of the preceding claims, characterized in that said upper body (1) has, formed therein, an expansion chamber (46) inside which air or steam are present and which acts as a pressure regulator.

14. Water compressed boiler according to any one of the preceding claims, characterized in that it comprises means (47) for thermally dividing said chamber (44) into a high zone (44a) and a low zone (44b), the temperatures of which are independent of each other.

15. Water compressed boiler according to Claim 14, characterized in that said means comprise a membrane (47) made of rubber or someother heat-insulating elastomer which is packed between said upper body (1) and said lower body (11).

16. Water compressed boiler according to Claim 14, characterized in that it comprises a high-temperature thermostat (48) integral with said upper body (1).

17. Water compressed boiler according to Claim 14, characterized in that it comprises a low-temperature thermostat (49) integral with said lower body (11 ).

18. Water compressed boiler according to Claim 14, characterized in that it comprises an electric resistance (51) housed in a suitable opening (50) formed in said lower body (11).

19. Water compressed boiler according to any one of the preceding claims, characterized in that it comprises a safety cap (5) co-operating with anti-unscrewing means (52) situated on said upper body (1).

20. Water compressed boiler according to Claim 19, characterized in that said anti-unscrewing means comprise a piston (52) which is movable vertically and housed inside a suitable guide seat (53) fixed to said upper body (11), said piston (52) being able to engage inside at least one hole (56) formed inside said safety cap 10412/E

(5).

21. Water compressed boiler according to Claim 20, characterized in that said piston (52) comprises actuating means (63) inside the chamber (44) defined between said upper body (1) and said lower body (11) and sensitive to increases or drops in the steam pressure inside said chamber (44).

22. Water compressed boiler according to Claim 21 , characterized in that said means for actuating the piston (52) comprise a resilient membrane (63) fixed by means of a suitable support element (60) to the internal wall of said upper body (1 ).

23. Water compressed boiler according to Claim 20, characterized in that said piston (52) comprises resilient recall means (54) fitted around it and inserted inside said guide seat (53).