AUTOMATIC DEVICE FOR OBTAINING FROTHY MILK

Abstract: The object of the invention is an automatic device for obtaining frothy milk comprising a first mixing assembly (30) which feeds a second frothing assembly (40), consisting of an expansion chamber (17), a milk feeding duct (31) being provided in the first assembly (30) inside a nozzle (13) for the pressurized steam, this nozzle being coaxial to the milk duct (31), the outlet of this duct slightly projecting over the steam outlet; the milk-steam mixture which is formed, tangentially flows to the expansion chamber (17), which has a circular section. Preferably the diameter of the nozzle (12) of the outflowing milk is about 1,1-1,2 mm, while the clear radial span of the annular section nozzle (13) of the outflowing steam is about 0,2 mm, the milk outlet projecting about 0,2 mm with respect to the steam outlet.

Description: The invention concerns a device for obtaining frothy milk which is usually used for preparing Italian cappuccino. At present the frothy milk is obtained by inserting a spout in a jug of cold milk, steam coming out of said spout. The operation of making froth by means of such a device gives good results only if the operator who holds the jug slightly moves the same for a predetermined time. The desired consistency of the froth therefore depends, to a large extent, on the operator. EP-A-0195.750 describes a device for producing frothy milk according to the preamble of claim 1. In such a device, the milk duct is in all cases perpendicular to the steam duct and the mixing takes place subsequent to contact between the milk and steam: with a short stay in a suction chamber or along a channel. This is not convenient. The aim of the invention is to provide an automatic device which overcomes the drawbacks of the known devices and which allows anyone to obtain frothy milk without any skill. The above aim has been achieved with a device comprising the features listed in the characterizing portion of the appended claim 1, that is the milk and steam feeding ducts terminate in first and second nozzles respectively, disposed coaxially and concentrically to define and annular space therebetween, the first nozzle projecting beyond the second nozzle. Preferably the diameter of the first nozzle (of the outflowing milk) is about 1, 1-1, 2 mm, and said annular space has a radial extent of about 0,2 mm, the first nozzle projecting beyond the second nozzle by a distance of about 0,2 mm. The milk can be fed by free fall, by arranging the feeding duct in a vertical position, or by suction using the vacuum created by the steam expanding around the milk nozzle. Preferably the mixing assembly further comprises an auxiliary lateral air duct, having an outlet disposed immediately downstream of said annular space surrounding the first nozzle. The auxiliary duct can be provided in this case with means for controlling the air flow therethrough. The auxiliary duct is provided in order to incorporate in the milk-steam mixture a percentage of air which can modify the consistency, that is the density, of the froth. Preferably the means for adjusting the air flow comprises a pin, engaged in said auxiliary duct, which tapers along its lenght such that the extent of insertion of the pin in the duct regulates a quantity of air sucked into the device by the effect of vacuum caused by the exit and expansion of the milk-steam mixture. The adjusting pin acts at the same time as a means of cleaning the duct. The milk duct, as well, can be provided with a cleaning pin; in such a case a milk inlet can be provided, perpendicualr to the duct. The frothing assembly preferably comprises, in a cylindrical expansion chamber an obstacle which diverts the flow. The upper part of the chamber can be made of a cover having a concave inner surface which facilitates the rotation of the milk-steam mixture and the outlet of milk froth. One embodiment of the invention is illustrated in the attached drawings, in which: Fig. 1 shows a top view of the device; Fig. 2 shows a partial section view, from the right with respect to fig. 1; Fig. 3 shows a section along line 3-3 of figure 1; Fig. 4 shows a horizontal section of the mixing assembly; in which the steam and milk inlet fittings have been rotated by 90° so that they can be seen; Fig. 5 shows a longitudinal section view of the adjusting device of the auxiliary air duct; Fig. 6 shows a section along line 6-6 of figure 5; Fig. 7 shows a section along line 7-7 of figure 5. In figures 1, 2 and 3 a device comprising a first assembly 30 adjacent to a second assembly 40 is shown. The two assemblies 30 and 40 are connected to each other by a duct 35 without throttle. The duct 35 tangenzially opens in an area 22a of a lateral wall 22 of a cylindrical chamber 17, comprising a bottom part 21, provided with an obstacle 20 capable of diverting the flow, and a cover part 18 having a concave inner surface 18a. The chamber 17 is jointed, in a lower part 22b of the lateral wall 22 substantially diametrically opposite the area 22a, with an outlet duct 19, which moves away from the housing 16 of the second assembly 40. The first assembly 30, illustrated in detail in figure 4, comprises an outer body 1 and an inner body 2 joined detachably to each other, for example by threading. In the inner body 2 a substantially cylindrical duct 31 can be seen, provided with a nozzle 12 (the diameter of which is about 1,2 mm). A cylindrical duct 7, jointed with a fitting 70 and perpendicular to the duct 31, communicates with the duct 31. Possibly a further duct (sectioned in fig. 1) can be provided, perpendicular to the duct 31 and communicating with it, placed diametrically opposite the duct 7. The lower end part of the duct 31 is surrounded by an annular nozzle 13 (the clear radial outletting span of which is about 0,2 mm). A duct 6, jointed to a fitting 60 and perpendicular to the axis of the nozzle 13, communicates with this nozzle 13. The nozzle 13 and the duct 31 are coaxial. The nozzle 12 of the duct 31 slightly projects (about 0,2 mm) with respect to the nozzle 13. Sideways to the nozzle 13 an auxiliary duct 8 is provided, the outlet 8a of which is immediately downstream of the throttle created by the nozzle 13. The duct 31, the nozzle 13 and the duct 8 let out in a fitting 15 jointed with the connecting duct 35 of the two assemblies 30 and 40. The duct 31, the fitting 15 and the inner body 2 are provided with O-rings 5. The end of the auxiliary duct 8 which faces outside is provided with an adjusting device shown in detail in figures 5, 6 and 7. Such device comprises a pin 9, which is received in the auxiliary duct 8, the head 9a of which is engaged, by threading, with a square washer 11 housed sliding in a seat 25 and subject to the returning of a helicoidal compression spring 10. The pin 9 has a longitudinal groove 14 the section of which increases proceeding towards the end 9b opposite the head 9a; the section of the pin 9 is consequently uniformly reduced from the head 9a towards the end 9b. A pin device 4 similar to the one previously described, but without groove 14, affects the duct 31, as shown in an exploded view in the upper part of figure 4. The device described above is a device capable of obtaining frothy milk, particularly useful in the preparation of Italian cappuccino. When using the device, the milk coming from the duct 7 enters the duct 31 and reaches the nozzle 12; at the same time the pressurized steam coming from the duct 6 fills the nozzle 13 and comes out. The milk which comes out of the nozzle 12 is carried by the steam expanding around the nozzle 12. In this step the mixing of the appropriately proportioned steam and atomized milk takes place. If necessary, in order to modify, as one wishes, the consistency of the froth to be made, a small percentage of air can be added by means of the auxiliary duct 8 and by the relative pin device 9. The quantity of air added can be controlled by screwing, or unscrewing, the pin 9 with respect to the washer 11; reducing the section of the pin 9 lengthwise, the major screwing of the pin, therefore the major penetration of the same in the auxiliary duct 8, allows the passage of a minor quantity of air and viceversa. The milk-steam and possible added air mixture then passes from the fitting 15, through the duct 35, in the chamber 17, in which, flowing tangentially, it takes on a rotatary movement. The thermomechanical action, together with the small percentage of air, causes the foaming of the milk making it frothy. The froth which is made, goes out, through the duct 19, from the chamber 17 and can be collected by the user. The cleaning of the device is advantageously carried out by pushing and releasing the pin 9 in the duct 8 and pushing and releasing the pin 4 in the duct 31. A possible exceptional maintenance operation can be facilitated by unscrewing the inner body 2 and removing the cover 18 of the chamber 17.

Claims: A device for obtaining frothy milk comprising an upstream mixing assembly (30) and a downstream frothy assembly (40), consisting of an expansion chamber (17), communicating with said upstream mixing assembly (30) through a duct (35) which opens tangentially into a circular section of said expansion chamber (17), a milk feeding duct (31) and a steam feeding duct (6) being provided in said upstream mixing assembly (30), characterized in that said milk feeding duct (31) and said steam feeding duct (6) terminate in a first nozzle (12) and in a second nozzle (13) respectively, such first and second nozzles (12, 13) being coaxial and concentrically disposed such that said second nozzle (13) surrounds said first nozzle (12) to define an annular space therebetween, and said first nozzle (12) projects beyond said second nozzle (13). The device according to claim 1, wherein said first nozzle (12) has a diameter of about 1.1-1.2 mm, and said annular space has a radial extent of about 0.2 mm, said first nozzle (12) projecting beyond said second nozzle (13) by a distance of about 0.2 mm. The device according to claim 1 or 2, wherein said upstream mixing assembly (30) further comprises an auxiliary lateral air duct (8) having an outlet (8a) disposed downstream of said annular space surrounding said first nozzle (12). The device according to claim 3, wherein said auxiliary lateral air duct (8) comprises means for controlling air flow therethrough. The device according to claim 4, wherein said means for adjusting air flow comprises a first pin (9) engaged in said auxiliary air duct (8), said pin tapering along its length such that the extent of insertion of the pin in said duct regulates a quantity of air sucked into said device. The device according to claim 1, further comprising a second pin (4) adapted to engage said milk feeding duct (31), said device further comprising a milk inlet perpendicular to and communicating with said milk feeding duct (31). The device according to anyone of the previous claims, wherein said expansion chamber (17) is a cylindrical chamber having a bottom portion (21) comprising a baffle (20) capable of diverting fluid flow within said chamber. The device according to claim 7, wherein said expansion chamber (17) further comprises a cover (18) having a concave inner surface (18a).

Inventors: SICCARDI, ALBERTO
Applicants: SICCARDI, ALBERTO
Application year: 1989
Main classification: A47J43
IPC codes: B01F5, A47J31