Title of Invention

"MIXING DEVICE, COFFE MACHINE PROVIDED WITH MIXING DEVICE AND USE OF MIXING DEVICE"

Abstract The present invention relates to a mixing device for aerating and frothing a product that comprises a fluid component and at least one further component, comprising a rotor (101) having a rotational axis (102) and a surface of revolution (4) defined by the rotor (101) upon rotation around its rotational axis (102), the surface of revolution (4) extending from a first axial (105) end to a second axial end (106), and the first axial end (105) being arranged upstream with respect to the second axial end (106); a motor in driving association with the rotor (101) for rotating the rotor about the rotational axis (102); and a product exit conduit disposed downstream of the rotor and configured for dispensing the aerated and frothed product of the fluid and at least one further component, which rotor (101) comprises a downstream part (108) and an upstream part (107). The invention relates furthermore to a beverage machine provided with the aforementioned mixing device.
Full Text Mixing device, coffee machine provided with mixing device and use of mixing
device
Field of the invention
The present invention relates to a mixing device that provides a frothy fluid
product. More particularly, the invention relates to a mixing device for mixing,
frothing, and dispensing a beverage, to a coffee machine provided with such a mixing
device and to the use of the mixing device.
More specific, the present invention relates to a mixing device according to the
preamble of claim 1.
A mixing device according to the preamble of claim 1 is known from WO
03/068039 in the name of Societe des Produits Nestle S.A, Switzerland.
Background of the invention
Espresso and other coffee and milk drinks are often prepared by mixing a powder
in water. Traditionally, a milk froth is provided to the drink by steam frothing.
Mixing devices are known for speedier preparation of such beverages and other
foods by mixing a powdered food component with a liquid, such as water. These
devices typically feed the powdered component into the water, which is often pumped
tangentially into the mixing chamber to create a whirlpool to mix the powder into the
water. The mixture is then fed to a mixing mechanism - also called a whipping
mechanism -, which is usually a rotating plate. The plate aerates the mixture and
produces a froth. The frothed mixture is usually dispensed into a container for drinking.
US-A-5,927,553, for example, discloses a mixing and dispensing apparatus with
a cruciform frothing blade. Other shapes of frothing blades are also known. For
instance, companies such as Rhea and Zanussi use whippers with an axially short disk
with very steep sloped walls. Other whippers have rotors with independent ramps
extending from a substantially flat plate. The known devices generally have their
greatest efficiency for preparing a small group of products.
EP 1,116,464 of Bravilor discloses a mixing device comprising a motor 14
provided with a driving shaft 15 carrying a rotor 16,17. The rotor consists of a circular
disc 16 provided with ribs 17. The ribs 17 are arranged on a circular end face of the
disc 16 and extend from this end face in axial direction. How the ribs 17 exactly extend
along the circular end face is neither described nor shown in EP 1,116,464. Only one
rib is shown in side view. This rib appears to extend about diagonally over the circular
end face of disc 16. The one rib 17 is at its radial outer ends tapered in the upstream
direction. The product exit conduit 11 of EP 1,116,464 is arranged on the upstream side
of the disc i 6, radially beside the ribs.
WO 03/068039 of Nestle discloses a mixing device according to the preamble of
claim 1. In this mixing device the rotor consists essentially of a tapering, preferably
conically tapering, rotor body which is, on the tapering rotor surface provided with
twisted, relatively small and accurately dimensioned grooves. The rotor housing has a
corresponding tapered inner surface, but is a little larger so that there is a small,
accurately defined gap between the housing and tapered rotor surface. Also at the
downstream side of the rotor there is a small, accurately defined gap between the back
surface of the rotor and the rotor housing. This accurate shape and accurate dimensions
of the rotor and grooves provided in it as well as the accurate dimensions of the gap
provide a very good frothing and aerating, which is highly desirable with instant coffee
and milk drink machines. When the rotational speed of the rotor is sufficiently high the
reliability of this mixing device on long term is also very good. However with
rotational speeds of the rotor below 10,000 revolutions per minute (rpm) there occurs
deposition of un-dissolved or partly dissolved components on the rotor and housing,
which deposition results in clogging of the gaps and grooves. This clogging is in those
kind of devices undesirable. Taking into account that the dimensions of gaps and
grooves must meet very accurate requirements for optimal results, this known mixing
device is relatively expensive in manufacturing and vulnerable for decrease in
performance in case of clogging.
There is thus clearly a need for a mixing device, especially for instant drink
machines, with a very good, if not improved, frothing and aerating effect, which is less,
preferably not, vulnerable for decrease in performance as a consequence of clogging.
The object of the invention is to provide such an improved mixing device.
Summary of the invention
This object is according to the invention achieved by providing a mixing
device according to claim 1. Starting from WO 03/068039, i.e. a mixing device for
aerating and frothing a product that comprises a fluid component and at least one
further component, comprising:
• a rotor having a rotational axis and a surface of revolution defined by the rotor
upon rotation around its rotational axis, the surface of revolution extending from
a firsl axial end to a second axial end, and the first axial end being directed to the
input container and arranged upstream with respect to the second axial end;
• a motor in driving association with the rotor for rotating the rotor about the
rotational axis; and
• a product exit conduit disposed downstream of the rotor and configured for
dispensing the aerated and frothed product of the fluid and at least one further
component;
the rotor comprising a downstream part and an upstream part;
this object is achieved
in that the downstream part comprises a rotational body having a first end surface
facing upstream, a second end surface facing downstream and a downstream rotational
surface facing in radial outward direction;
in that the upstream part comprises an upstream rotational surface facing in radial
outward direction, the upstream rotational surface being provided with ribs extending
in axial (A) and/or radial (R) direction, the ribs having radial edges facing in radial
outward direction, chambers being defined between adjacent ribs, the first end face and
the downstream rotational surface,
in that the surface of revolution is defined by the downstream rotational surface and the
radial edges of the ribs.
By providing the chambers there are created spaces in which un-dissolved or
partially dissolved particles can dissolve, which dissolving is considerably promoted by
the ribs which create high turbulences. Also air is easily trapped in those chambers and
beaten by the high turbulences into the liquid, which enhances the frothing effect.
In a preferred mode, the downstream rotational surface is provided with grooves
extending from the first to the second end surface. The higher turbulence caused by the
ribs thus propagates in the grooves and between the rotor and rotor housing. The higher
turbulence thus also counteracts deposition of particles on the rotor and rotor housing
downstream of the ribs and chambers. Preferably, in each said chamber debouches at
least one ot said grooves.
The chambers are relatively large with respect to the grooves. Viewed in axial
direction the passage width (in mm2) of the grooves debouching in one chamber is
smaller than the passage width (in mm2) of this one chamber, also viewed in axial
direction. This (axial) passage width of the grooves (in mm2) debouching in one
chamber will be between 5 and 25 % of the (axial) passage width (in mm2) of said one
chamber. Expressed differently and viewed in tangential direction, the width of each
chamber (in mm) will be larger than the width (in mm) of the grooves debouching in it.
The grooves in the downstream part of the rotor act to keep the rotating motion of
the fluid (induced by the upstream part of the rotor) going.
Further tests with the invention revealed that as a consequence of the new and
inventive rotor design, the requirements with respect to the accuracy of the dimensions
of gaps, grooves and rotor is of much less importance than in the case of the design of
WO 03/068093. On the one hand this provides an easier manufacturing and on the
other hand it reduces the chance on a reduced performance in case some depositing of
particles might take place. In other words the performance of the present mixer is less
susceptible for negative effects due to depositing of particles.
In order to make use of centripetal forces for frothing and aerating, it is
advantageous when the diameter of the surface of revolution at the first axial end is
smaller than the diameter of the surface of revolution at the second axial end.
In order to support transfer of product from the chambers to the grooves
and to the downstream of the rotor, it is advantageous when, with respect to the
rotational axis, the radial edges of the ribs taper, preferably taper conically, in upstream
direction. This creates a turbulence which increases along the ribs in downstream
direction.
In order to support transport of product along the downstream part of the
rotor and to counteract, preferably prevent, there a decrease in the level of turbulence
earlier created, it is according to the invention advantageous when, with respect to the
rotational axis, the downstream rotational surface tapers, preferably tapers conically, in
upstream direction.
According to a further embodiment of the invention it is advantageous
when the upstream rotational surface is a cylindrical surface. On the one hand this
provides that the passage width of the chambers increases in axially downstream
direction, whilst on the other hand this provides an easier manufacturing.
According to a further embodiment of the invention it is, with respect to an
easier production of the rotor, advantageous when the ribs extend essentially strictly in
axial direction and/or essentially strictly in radial direction.
In order to promote breakage of larger solid particles upon entering the
chambers of the rotor as well as to enhance turbulence effects, it is according to the
invention advantageous when the ribs have a rounded upstream edge.
According to still a further embodiment of the invention it is advantageous
when the axial length of the upstream part and the axial length of the downstream part
are about the same. The longer the downstream part will be, the more uniform the air
bubbles will become. However, also the longer the upstream part is, the better
ingredient and air are dissolved in the liquid. Taking into account the limited length
available for the rotor, this results in the compromise to make both parts about the same
length.
Concerning features and advantages of the present invention , similar or identical
to the device of WO 03/068039; reference is made to the description of WO 03/068039,
especially but not exclusively to pages 2 and 3 of WO 03/068039.
Brief description of the drawings
Fig. ! is a schematic perspective view of a rotor for the purpose of defining some
terms used in claim 1;
Fig. 2 is a perspective view of a rotor according to the invention;
Fig. 3 is a perspective view of a preferred embodiment of the invention
comprising a rotor according to fig. 2;
Fig. 4 is a cross-sectional view of the embodiment of fig. 3; and
Fig. 5 is an exploded view of the embodiment of fig. 3.
Detailed description of the drawings
Figure 1 explains with a perspective and schematic view some of the terms used
in claim 1. Figure 1 shows a rotor 1, which as an example has the form of a rectangular
plate. This rotor 1 is rotatable around a rotational axis 2. The rotor 1 has a radial outer
edge 3. When one rotates the rotor 1 around its rotational axis 2, the outer edge 3 will
describe a rotational contour 4, which in this example will be cylindrical. This
rotational contour 4 is called "the surface of revolution defined by the rotor upon
rotation around its rotational axis", in short "the surface of revolution". This "surface of
revolution" thus is primarily a notational or hypothetical surface in mathematical sense.
In case the rotor would be for example a cylinder having the rotational axis coinciding
with the cylindrical axis, the cylindrical outer surface of this cylinder would coincide
with its "surface of revolution".
Referring further to figure 1, the surface of revolution 4 extends between a first
axial end 5 and second axial end 6. Assuming the first axial end 5 is facing in an
upstream direction, the first axial end 5 is arranged upstream with respect to the second
axial end, and the rotor can be divided in an upstream part 7 and downstream part 8.
Correspondingly the outer edge 3 is divided in an upstream part 3b and a downstream
part 3 a.
Further in figure 1, arrow A indicates the axial direction (the arrow A points in
the downstream direction), arrow R indicates the radial direction (the arrow points in
the radial outward direction), and arrow T indicates the tangential direction.
Figure 2 shows a rotor according to the invention. The terms as explained in
figure 1 are indicated in figure 2 with the same reference number increased by 100. The
entire rotor is indicated by 101. The reference number 104 has been omitted in order
not to disturb the clearness of figure 2. It will however be clear that, in the case of
figure 2, the surface of revolution is a conical surface defined by the tapering surface
parts 103a and tapering edges 103b.
The rotor 101 comprises a downstream part 108 and an upstream part 107.
The downstream part 108 is a rotational body 109. The rotational body 109 has a
first end surface 110 facing upstream (opposite to arrow A); a second end surface 106
facing downstream (in the direction of arrow A); and a downstream rotational surface
103a. The downstream rotational surface 103a faces in radial outward direction and
extends from the first end surface 110 to the second end surface 106. In this case the
second end surface 106 corresponds to the so called second axial end of the rotor 101.
The upstream part 107 has an upstream rotational surface 112. This upstream
rotational surface 112 faces in radial outward direction (arrow R in fig. 1). The
upstream rotational surface 112 is provided with ribs 113. The ribs 113 extend in radial
direction and in axial direction, i.e. the extension of the ribs has a radial as well as an
axial component. The extension of the ribs thus can also have a tangential component
(direction arrow T) larger than zero. In the shown embodiment the tangential
component of the extension of the ribs is zero so that the ribs 113 extend in strictly
axial and strictly radial direction.
Chambers 114 are defined between adjacent ribs 113, the first end face 110 of the
rotational body 9, and the upstream rotational surface 112. Those chambers 114 are
open in the radial outward direction (arrow R) and in the upstream direction (opposite
to arrow A).
Each chamber 114 is connected via at least one groove 111 with the downstream
side 106 of the rotational body 109. Those grooves 111 are provided in the downstream
rotational surface 103a.
The surface of revolution (not indicated with a reference number, but compare
reference number 4 in figure 1) of the rotor 101 is defined by the downstream rotational
surface 103a and the radial edges 103b of the ribs 113.
In the embodiment of figure 2 the downstream rotational surface 103a and the
radial edges 103b of the ribs 113 both taper with respect to the rotational axis. As in
this embodiment both tapers have a substantially constant taper angle (in case of the
rotational surface 103a this taper angle is also called a surface angle), the surface of
revolution of this rotor 101 is essentially conical. It is however noted that both tapers
can also be different; that the radial edges 103b and/or the rotational surface 103a can
also be non tapered; and that the radial edges 103b and/or the rotational surface 103a
can also have a non-constant taper (i.e. the taper follows a curved line).
In the next following a rotor 101 according to the invention will be discussed in
relation to a mixing device (comprising such a rotor) according to the invention, which
is shown in figure 3-5. With some exceptions, such as the rotor, the embodiment of the
invention as shown in figure 3-5 is identical to the mixing device as described in WO
03/068039. This WO 03/068039 is in this respect fully incorporated by reference.
Although the embodiment of the invention according to figures 3-5 is a preferred
embodiment, it will be clear that scope of this invention is defined by the claims and
not by the preferred embodiment.
Referring to figs. 3 and 4, a preferred embodiment of the invention is a mixing
device 10 that includes an input container 12. The input container 12 comprises a bowl
portion 14 with a tangential inlet 16 for feeding a fluid under pressure. An
automatically controlled valve is preferably provided to control the fluid flow into the
input container 12. The fluid is introduced through the inlet at a speed selected to
produce a swirling flow, preferably substantially a whirlpool effect.
A component to be mixed with the fluid, preferably a powdered food substance,
is fed into powder inlet 18, which preferably includes an opening at the top of the bowl
portion 14. The powder can be fed by hand or automatically by a powder source,
preferably disposed above the device 10. The powder source preferably has a dosing
mechanism, such as a dosing screw, to automatically dose a predetermined amount of
powder into the input container 12. A lip 20 extends around the interior of the powder
inlet 18, protruding into the bowl portion 14 to prevent the swirling fluid from exiting
the input container 12 by the upper side thereof. A suction is applied to orifice 21,
connected to the underside of the lip 20 for extracting any splashed material. The
powder inlet is sufficiently large to receive the powder poured therein and also to
receive a sufficient amount of air for mixing with the fluid and component.
In the embodiment shown, a throat portion 22 of the input container 12 is
disposed below the bowl portion 14. The throat portion 22 preferably has a narrower
diameter than the bowl portion 14 and has a throat opening 24 disposed on a lateral
side, as shown in fig. 2. The throat portion 22 is preferably generally coaxial with the
bowl portion 14 and narrows substantially evenly along the axis of the bowl portion 14.
This improves the fluid flow therein and reduces any trapping of powder. Preferably, a
transition between the bowl portion 14 and the throat portion 22 has an inward bend 25,
followed by a sloped portion 27, which is followed by an outward bend 29, in crosssection.
Referring to figs. 4 and 5, a rotor assembly is in fluid communication with the
input container 14, preferably at the throat opening 24. The rotor assembly includes a
rotor 101, A motor 30 drives rotor shaft 32, which drives the rotor 101 so that the motor
30 drives the rotor at about rotor axis 34 rotational axis 102, also called the rotor axis.
A motor controller is preferably provided to control the operation and speed of the
motor 30.
The preferred rotor 101 has a conical surface of revolution 104. The conical
surface of revolution 104 preferably faces outwardly with respect to the rotor axis 102
and can have a substantially straight cross-section, as in the embodiment shown, or can
be curved in cross-section with a taper angle that varies along the axial length of the
rotor 101. The surface of revolution in the embodiment shown extends at a surface
angle 42 to the rotor axis 102. Surface angle 42 is the average angle between first and
second axial end 105, 106, and the surface of revolution 104 is preferably substantially
continuous about its circumference between the axial ends 105, 106. The angle may
change beyond the axial ends 105, 106. Surface angle 42 is preferably about between
5° and 85°, more preferably about between 10° and 45°, still more preferably about
between 15° and 35°, and most preferably about between 20° and 30°.
The preferred surface of revolution 104 extends substantially between first and
second axial ends 105, 106. As the surface of revolution 104 is conical or tapered, the
first axial end 105 has a smaller diameter than the second axial end 106. The first axial
end 105 preferably faces the interior of the input container 12, with the second axial
end 106 disposed on an opposite side of the surface of revolution 104. In the preferred
embodiment, the diameter of the second axial end 106 is at least about 10% larger than
the diameter of the first axial end 105. More preferably, second axial end diameter is
about between 1.25 and 2.5 times the size of the first axial end diameter. The surface of
revolution 104 preferably has an axial length of about between a quarter and twice the
size of the first axial end diameter. In one embodiment, the first axial end diameter is
about between 13 to 25 mm, and the second axial end diameter is about between 30 and
35 mm, with an axial length between the axial ends of between about 10 and 25 mm.
The diameter of the rotor, including of the axial ends are preferably measured to widest
point at the station being measured along the axis 102. Thus, the diameter of a rotor
with protrusions, such as ribs 113, is measured to the tip of the protrusions. Grooves
1 1 1 on the surface of revolution are not deeper than about 6 mm in the preferred
embodiment.
The surface of revolution 104 preferably has a surface area of at least about 800
mm2 and more preferably at least about 100 mm2, and preferably at most about 3000
mm2 and more preferably at most about 2000 mm2. Most preferably, the surface area is
of from about 1000 to 1200 mm2. This surface area is calculated taking the cross
sections of the surface as being circular and having the diameter of the rotor at the
relevant axial sections as described above.
Additionally, in the embodiment shown, the axial ends 105, 106 are located at the
extreme ends of the frustoconical rotor 101. In other embodiments, the axial ends 105,
106 may be located remotely from the ends of the rotor. In one embodiment, the first,
smaller axial end 105 is defined as being at the portion of the tapered rotor where the
diameter becomes at least about 13 mm. Thus, this embodiment has a surface of
revolution measured from the location on the rotor where the diameter becomes at least
about 13 mm. This alternative embodiment may also have a second surface portion of
the rotor that extends in the direction away from the second axial end, and which can be
continuous and can follow the adjacent surface of revolution. The second surface
portion may extend to the most upstream end of the rotor. In another embodiment, the
surface portion is measured from the location on the rotor where the diameter becomes
at least about 20 mm, and in yet another embodiment, it is measured from the location
on the rotor where the diameter becomes at least about 25mm.
In the preferred embodiment, the second or rear rotor face 48 preferably includes
a recessed portion 50 facing in an opposite direction from the front face 44. In the
drawings, the first 44 and second 48 rotor faces are disposed at the first and second
axial ends 105, 106. In the alternative embodiment described in which one or both of
the axial ends 105, 106 is located remotely from the end of the rotor itself, one or both
of the axial ends and the rotor faces, respectively, are also disposed remotely from each
other.
The rotor 101 is disposed within a rotor housing 52, which in the embodiment
shown is integral part of unitary construction with the input container 12. The preferred
rotor housing 52 has an inner housing surface 54 with a shape substantially
corresponding to the surface of revolution 104. A shear gap 56 is defined between the
housing surface 54 and surface of revolution 104 that has a width selected to provide a
sufficient flow rate and energy, transfer to the mixture, for a desired foaming effect.
Measured in a direction perpendicular to the rotor axis 102, the shear gap 56 is
preferably at least about 1.5 mm, more preferably at least about 1.8 mm, and most
preferably at least 2 mm. Measured in this direction, the shear gap 56 is preferably at
most about 3 mm and more preferably at most about 2.5 mm. In one embodiment the
shear gap h about 2-2.5 mm, such as 2.25 mm. The conical shape of the surface of
revolution 104 provides a long shear gap 56 for acting on the fluid mixture, while
providing a pumping action and without requiring an extremely large radius.
As shown in fig. 2 and 5, the downstream surface 103a preferably defines a
plurality of rounded grooves 111, extending between the first 110 and second 106 end
surfaces. The preferred grooves 111 could be twisted to spiral along the axial length of
the rotor, however in the shown embodiment they extend in axial direction without
twist. The grooves 1 1 1 of the present embodiment are about between 0.5 and 3 mm
deep. The grooves 111 are preferably configured and dimensioned for keeping the
relating motion of the fluid going. In the meantime the sheer gap 56 between the rotor
and the housing acts to give the air bubbles in the froth a more uniform size, by
breaking up the larger bubbles and creating smaller bubbles out of them. The more
uniform size of the air bubbles gives the froth a belly appearance and the smaller size
gives a better stability. In case of twisted grooves 111, the motor 30 can turn the rotor
101 in or against the direction of the grooves 111 depending on the pumping and
frothing effect desired. But also in case of non-twisted grooves 111, the motor can turn
the rotor in two opposing directions.
A wall member 57 including a back wall 58 is disposed behind the rotor, facing
the second axial end 106 and the rear rotor face 48. Like in WO 03/068039, the back
wall 58 can include protrusions, which are preferably at least one rib that protrude
towards the rotor 101. However, contrary to WO 03/068039, the back wall 58 can, due
to the present rotor design also be without protrusions.
The rotor 101 is preferably spaced from the wall member 57. In the preferred
embodiment, the second axial end 106 of the rotor 101 is spaced from the wall member
57 at a spacing 90 of at least about 1,5 mm, more preferably at least about 2 mm, and
most preferably at least about 3 mm. The spacing between the rotor 101 and the wall
member is preferably at most about 8 mm, more preferably at most about 6 mm, and
most preferably at most about 5 mm. A practical embodiment has a spacing of about
2.5 mm near the centre and about 4 mm near the outer edge of the second end surface
106.
In order to provide sufficient room for the mixed and frothed fluid to exit the
mixing device, the back wall 58 preferably has a larger outer diameter than the rotor
101, preferably at least about 20% larger and more preferably at least about 30% larger,
and further are preferably at most about 60% larger, and more preferably at most about
40% larger. For example, the diameter of the back wall 58 can be about 37,5% larger
than the diameter of the second axial end of the rotor. The outer diameter of the back
wall 58 of the preferred embodiment is at least about 40 mm and at most about 60 mm.
A product exit tube 72 is disposed downstream of the rotor 101 and back wall 58
and is disposed to dispense the foamed fluid mixture. The product exit tube 72 is shown
as an integral part of unitary construction with the input container 12. The product exit
tube 72 preferably comprises a conduit with a diameter selected according to the final
product that is to be dispensed. The preferred product exit tube 72 has an internal
diameter of about between 2 mm and 8 mm for embodiments intended to prepare
several different milk and coffee beverages. Embodiments intended primarily for coffee
preferably have a product exit tube 72 with an internal diameter of about between 2 mm
and 5 mm, and in embodiments intended primarily for milk, the internal diameter is
preferably from about 4 mm to 8 mm. The diameter of the product exit tube 72 is
selected to obtain the desired pumping performance from the rotor 101. Increasing the
diameter of the conduit allows a faster flow, while decreasing the diameter provides
more back-pressure to retain the fluid mixture in the rotor assembly and input chamber
12 for a longer time. In embodiments used for milk and coffee beverages, the internal
diameter of the exit tube 72 is according to the invention between 4 mm and 6 mm. An
exit tube 72 with an internal diameter smaller than 2 mm, has the disadvantage that the
properties of the materials used to manufacture the tube will increasingly (with
decreasing diameter) start to interfere with the fluid. This could result in the liquid not
wanting to pass through the exit tube as a consequence of for example adhesy, cohesy,
hydrophobic and hydrophilic properties.
In use, the fluid is tangentially introduced into the input container 12 through
tangential inlet 16. In the preferred embodiment, the fluid comprises water, and the
flow rate is about between 3 mL/sec and 30 mL/sec, more preferably about between 5
mL/sec and 15 mL/sec, and most preferably about between 9 mL/sec and 12 mL/sec.
At the time or preferably after the water flow into the input container 12 is commenced,
a powdered food component, such as a powdered coffee product and/or powdered milk,
is dosed into the water through powder inlet 18. Preferably the powder dosing begins at
least about 0,1 sec after the water dosing begins and more preferably at least about 0.3
sec. later, and preferably at most about 3 sec later, and more preferably at most about
1.0 sec later. Preferably the water is continued to be fed into the input container 12 until
the powder dosing is stopped, and preferably at most about 8 sec after the powder
dosing ends, and more preferably at most about 3 sec later, and preferably at least about
1.0 sec later.
The water and powder start getting mixed in the swirling flow within the input
container 12, including the throat portion 22. The rotor 101 is rotated by the motor 30
at a speed sufficient for pumping the mixture towards the product exit tube 72 and for
producing the desired foaming and aeration effect. The rotor 12 sucks in air for
incorporation into the mixture. The configuration and location of the back wall 58 with
respect to the rotor 101 continues the frothing effect, increasing the efficiency of the
device. The rotation of the rotor 101 and the shape of the back wall 58 centrifugally
keep the fluid product from accumulating behind the rotor. The speed of the rotor 101
is preferably variable to enable a speed selection to deliver the desired amount of
energy to the mixture to produce the desired frothing. For obtaining products of certain
qualities, the rotation speed of the rotor 101 is varied between two or more speeds
during the preparation of a single product.
The device 10 provides a high specific energy dissipation to generate a milk froth
and a moderately low specific energy dissipation to obtain a high quality coffee crema
in the same unit. The frothed product is then dispensed through the product exit tube
72.
It has been found that to generate an authentic quality milk froth when using a
milk powder in a beverage dispenser, the specific energy dissipation should be above
about 1 J/g of product, which includes milk: powder and water together. Authentic milk
froth as referred to in the present application is a frothed product with at least an equal
volume of milk foam compared to the volume ofliquid. The milk, foam in the product
having authentic milk, froth preferably has a density of about between 50 mg/L and 300
mg/L. An authentic cappuccino can be made with the device of the present invention,
which has a volume made up by about 1/3 coffee, about 1/3 frothed milk foam, and
about 1/3 of milk that remained liquid after frothing. The preferred milk fraction in the
authentic cappuccino has a volume that is at least as large as the volume of the liquid
portion. The foam of the frothed milk in the final prepared beverage product is
preferably stable, having at least about 2/3 of the foam volume remaining after 10
minutes.
The energy dissipation of the device can be controlled by adjusting the shear
gap, rotor speed, and product flow rate, although these quantities are interdependent. A
reduction in the shear gap, an increase in rotor speed, and a decrease in flow rate will
provide a higher energy dissipation. The preferred flow rate is between at least about 5
g/sec and up to about 30 g/sec, and more preferably at least about 8 g/sec and up to
about 15 g/sec. If the size of the gap is reduced, the flow rates will correspondingly be
reduced and the amount of air drawn into the gap will be reduced as well, reducing
foaming and aeration, and friction is increased. Also, if the rotational speed (i.e.,
"rpm") is increased, noise and cost of the machine will increase as well.
The embodiments described above allow a device of compact size, and with a
desirable flow rate for preparing individual drinks to be provided without requiring
extremely high rotor speeds, such as of above about 30,000 rpm. The preferred
rotational speed used for foamed coffee or milk froth are of from 10,000 to 30,000 rpm,
most preferably between 10,000 to 25,000 rpm.
However, also in the range below 10,000 rpm there is, compared with prior art
devices operated at the same rotor speeds below 10,000 rpm, an improved performance
with good frothing results. With respect to the prior art, good results are obtained with
rotor speeds as from 3,000 rpm, preferably as from 5,000 rpm, more preferably as
from 7,500 rpm, but still below or at 10,000 rpm.
The rotor design according to the invention enables for example to operate a
device according to WO 03/068039 to be operated at lower rotor speeds (i.e. lower
rpm) without decreasing its reliability.
Making the ribs at the upstream part of the rotory (i.e. the part where the hot
water/ingredient mixture coming from the input container 12 above enters the rotor
assembly) allows for (little) chambers 112 where un-dissolved larger ingredient
particles can enter without blocking the movement of the rotor or cause any other
damage. This consequently also allows for coarser ingredients (components) to be used.
In the chambers 112 also air can be trapped, which is, when the rotor is rotating, beaten
in the hot water-ingredient-mixture so that the frothing process is improved.
When rotated at sufficient high speed, the ribs 112 create a greater turbulence
enforcing contact between the water and the un-dissolved ingredient (component). In
practise this greater turbulence extends not only over the upstream part of the rotor but
also cover the downstream part (thus essentially over the entire rotor), which forces all
the ingredient to be dissolved before it can stick to the rotor. In case some un-dissolved
or partially dissolved ingredient is still sticking to the surface of the rotor or to the
inside of the rotor chamber, this sticking ingredient will be removed by the violent
movement of the water.
The improved design of the rotor also makes - as experiments indicate - the
dimensions as given in WO 03/068039 less critical.
While illustrative embodiments of the invention are disclosed herein, it will be
appreciated that numerous modifications and other embodiments may be devised by
those skilled in the art. Therefore, it will be understood that the appended claims are
intended to cover all such modifications and embodiments that come within the spirit
and scope of the present invention.







We Claim:
1. A mixing device for aerating and frothing a product that comprises a fluid
component and at least one further component, comprising:
• a rotor (101) having a rotational axis (102) and a surface of revolution (4)
defined by the rotor (101) upon rotation around its rotational axis (102), the
surface of revolution (4) extending from a first axial end (105) to a second axial
end (106), and the first axial end (105) being arranged upstream with respect to
the second axial end (106);
• a motor in driving association with the rotor for rotating the rotor (101) about the
rotational axis (102); and
• a product exit conduit disposed downstream of the rotor and configured for
dispensing the aerated and frothed product of the fluid and at least one further
component;
the rotor comprising a downstream part (108) and an upstream part (107);
characterized
in that the downstream part (108) comprises a rotational body (109) having a first end
surface (110) facing upstream, a second end surface (106) facing downstream and a
downstream rotational surface (103a) facing in radial outward direction;
in that the upstream part (107) comprises an upstream rotational surface (112) facing in
radial outward direction, the upstream rotational surface (112) being provided with ribs
(113) extending in axial (A) and/or radial (R) direction, the ribs having radial edges
(103b) facing in radial outward direction, chambers (114) being defined between
adjacent ribs (113), the first end face (110) and the upstream rotational surface (112);
and
in that the surface of revolution is defined by the downstream rotational surface (103a)
and the radial edges (103b) of the ribs (113).
2. A mixing device according to claim 1, wherein the downstream rotational surface
(103a) is provided with grooves (111) extending from the first (110) to the second
(106) end surface.
3. A mixing device according to claim 2, wherein in each said chamber (114)
debouches at least one of said grooves (111).
4. Mixing device according to one of claims 1 to 3, wherein the diameter of the surface
of revolution at the first axial end (105) is smaller than the diameter of the surface of
revolution at the second axial end (106).
5. Mixing device according to one of the preceding claims, wherein, with respect to the
rotational axis, the radial edges (103b) of the ribs (113) taper, preferably taper
conically, in upstream direction.
6. Mixing device according to one of the preceding claims, wherein, with respect to the
rotational axis (102), the downstream rotational surface (103a) tapers, preferably tapers
conically, in upstream direction.
7. Mixing device according to claim 6, wherein the upstream rotational surface (112) is
a conical surface which tapers in upstream direction at an angle lower than the angle at
which the downstream rotational surface (103a) tapers.
8. Mixing device according to one of the preceding claims, wherein the upstream
rotational surface (112) is a cylindrical surface.
9. Mixing device according to one of the preceding claims, wherein the part of the
surface of revolution determined by the radial edges (103b) of the ribs (113) tapers,
preferably tapers conically, in upstream direction.
10. Mixing device according to claim 9 in combination with claim 6, wherein the angle
of taper of the downstream rotational surface (103a) is different from, preferably larger
than, the angle of taper of the part of the surface of revolution determined by the radial
edges (l()3b) of the ribs (113).
11. Mixing device according to one of the preceding claims, wherein the ribs (113)
extend essentially strictly in axial direction (A) and in radial direction (R).
12. Mixing device according to one of the preceding claims, wherein the axial length of
the upstream part (107) and the axial length of the downstream part (108) are about the
same.
13. Mixing device according to one of the preceding claims, more in particular one of
claims 2 or 3, wherein, viewed in tangential direction, the width of each chamber (114)
is larger than the width of the grooves (111) debouching in it.
14. Mixing device according to one of the preceding claims, wherein the motor and
rotor are configured for providing energy dissipation to the product of about between 1
J/g and 2.5 J/g with a product flow rate of about between 5 g/sec and 30 g/sec.
15. Mixing device according to one of the claims 1-13, wherein the motor and rotor are
configured for providing energy dissipation to the product selectively in at least the
range of about 0.5 J/g to 1.5 J/g with a product flow rate of about between 5 g/sec and
30 g/sec.
16. Mixing device according to one of the preceding claims, wherein the surface of
revolution (4) is oriented at a surface angle to the rotational axis of about between 5°
and 85°.
17. Mixing device according to claim 16, wherein the surface is about between 10° and
45°.
18. Mixing device according to one of the preceding claims, wherein the surface of
revolution (4) has an area of about between 1000 mm2 and 3000 mm2, more preferably
from about 1000 to 1200 mm2.
19. Mixing device according to one of the preceding claims, wherein the surface of
revolution (4) has an axial length of about between a 1/8 and 4 times, preferably of
about between 1/4 and 2 times, the size of the diameter of the surface of revolution at
the first axial end.
20. Mixing device according to one of the preceding claims, wherein the surface of
revolution (4) is a conical surface and has a substantially constant surface angle
between the first (105) and second (106) axial end.
21. Mixing device according to one of the preceding claims, wherein the rotor housing
has a shape substantially corresponding to the surface of revolution.
22. Mixing device according to claim 21, wherein a shear gap is defined between the
housing and the rotor, perpendicular to the rotational axis, as having a width of about
between 1.0 mm and 3,0 mm.
23. Mixing device according to one of the preceding claims, wherein the grooves (111)
have a depth of at most about 8 mm.
24. Mixing device according to one of the preceding claims, further comprising a first
wall member disposed downstream of and facing the second axial end, the first wall
member being spaced from the second axial end by about between 2.0 mm and 6 mm.
25. Mixing device according to claim 24, wherein the first wall is spaced from the
second axial end by about between 3 mm and 5 mm.
26. Mixing device according to one of the preceding claims, further comprising a motor
controller configured for selective operation at various speeds.
27. Mixing device according to claim 26, wherein the motor controller is configured for
varying the rotation speed of the motor between first and second speeds during the
production of a single product.
28. Beverage machine provided with a mixing device according to one of the preceding
claims, comprising a water supply system for the fluid component and at least one
container for the at least one further component.
29. Use of a mixing device according to one of the preceding claims in preparing a
coffee, cocoa and/or milk drink.
30. Use of a mixing device according to one of the preceding claims wherein it is run at
rotational speed below or at 10,000 rpm.
31. Use of a mixing device according to one of claims 1 to 29, wherein it is run at a
rotational speed above 10,000 rpm.


Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=Kg3geX0T2O1iTDue3VY1jg==&loc=+mN2fYxnTC4l0fUd8W4CAA==


Patent Number 279187
Indian Patent Application Number 2160/DELNP/2007
PG Journal Number 03/2017
Publication Date 20-Jan-2017
Grant Date 13-Jan-2017
Date of Filing 20-Mar-2007
Name of Patentee NESTEC S.A.;
Applicant Address AVENUE NESTLE 55, CH-1800, VEVERY, SWITZERLAND
Inventors:
# Inventor's Name Inventor's Address
1 VERHOEVEN, ROMANUS EDUARD; JAN GLIJNISWEG 31C, NL-1703 RK HEERHUGOWAARD; NETHERLAND
2 HUBIBERTS, JOHANNES, THEODORUS EMERENTIA; HOUTDUIF 20, NL-1715 TA SPANBROEK; NETHERLAND
3 KOOPMAN,CARLOS NIKOLAAS JOSEF MARIA; KORTEWEG 2, NL-1702 PE HEERHUGOWAARD; NETHERLANDS.
4 WAN DE LEIJGRAAF, ANDREAS RAYMOND HONTHORSTLAAN 228, NL-1816 TJ ALKMAAR; NETHERLAND.
PCT International Classification Number A47J 31/40
PCT International Application Number PCT/EP2005/010229
PCT International Filing date 2005-09-22
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 04077663.5 2004-09-27 EUROPEAN UNION