Frothing machines for milk-based beverages

Abstract

A frothing machine comprising a chamber (1) for receiving milk or liquid and powder, drive means (2) adapted to drive a stirrer (3) adapted to rotate in milk or a milk-based liquid to mix the milk or liquid with the powder, and heating means (4) adapted to heat the milk or liquid. The stirrer has a cover means (11) arranged to prevent the powder from being deposited in a coil on the stirrer.

Description

[0001] The invention relates to a frothing machine for milk-based beverages.

[0002] Espresso-based coffee drinks, such as café lattes and cappuccinos, have become increasingly popular, and consumers want to be able to produce these drinks easily and reliably. Conventionally, baristas are trained to use the steam produced by an espresso machine to heat and froth milk in a jug to produce the hot milk and foam required for these drinks. Producing the right amount of hot milk and foam without burning the milk or damaging the jug requires some training or experience. Smaller espresso machines are also difficult to use to handle milk.

[0003] Many stand-alone milk frothing machines suitable for home or small-scale commercial use have been produced. EP1656866 discloses a frothing machine with a storage tank for receiving a milk-based liquid food with a magnetic whipper. The magnetic whipper drive system generates a magnetic field that drives the whipper to rotate in the storage tank. The system, the whipper and the whipper positioning unit break or prevent the symmetrical circulation of the liquid around the center of the vertical axis of the storage tank. A heating unit is arranged in association with the storage tank for heating the liquid. It is used to prepare foam from the milk-based liquid food.

[0004] GB2454421 discloses a device for frothing milk having a rotating heating element inserted into the milk. The device is equipped with a stirring attachment for producing foam and a paddle attachment for producing a creamier mouthfeel.

[0005] Another problem with known frothers is that the milk tends to burn on the element because when the frother frothes the milk, the user immediately pours the milk out and leaves a small residue which burns on the element. If not cleaned quickly, the burnt residue becomes difficult to remove and can also affect future performance. The standard approach to this is to reduce the temperature of the heated milk to around 60 degrees Celsius, but at this temperature, the frothed milk is not suitable for other beverages such as hot chocolate, which require a higher temperature to be palatable.

[0006] GB2486872 represents a significant advance in the field of domestic milk frothing machines, but is limited to use with milk.

[0007] The present invention therefore seeks to provide a frothing machine which can be used to produce a wider range of beverages, in particular milk-based beverages.

[0008] According to the present invention, a frothing machine for milk-based beverages is provided, which comprises a storage tank for receiving milk or a milk-based liquid, a magnetic drive device suitable for driving a detachable stirring device, the storage tank having a substantially vertical wall and a flat bottom, the stirring device being suitable for rotating in the milk or milk-based liquid to mix the milk or milk-based liquid being heated, the frothing machine further comprising a heating device, the heating device being suitable for heating the milk or the milk-based liquid, the magnetic drive device being located outside the storage tank and below the flat bottom of the storage tank, wherein the stirring device comprises an agitator comprising a plurality of coils, the agitator being mounted on a support member arranged to keep the agitator away from the flat bottom, the stirring device further comprising a cover device, which extends to substantially cover the space above the agitator when the agitator is located on the flat bottom.

[0009] Preferably, the agitator has a width or diameter in a plane coplanar with the flat base and the cover means has a width or diameter of substantially the same size as the agitator.

[0010] Preferably, the width or diameter of the cover means is greater than the width or diameter of the stirrer.

[0011] Preferably, the support comprises an annular upright wall which, in use, lies on the flat bottom of the tank, the wall being connected to the axial spindle by radial arms, and a stirrer being rotatably mounted on the support, the rotatably mounted stirrer being rotatable by a magnetic drive, wherein the support holds the stirrer away from the flat bottom of the tank, the stirrer being held in place by the stirring means rather than the magnetic drive.

[0012] The provision of the cover device of the present invention enables the frothing machine to produce milk-based beverages, such as hot chocolate or follow-on milk, which cannot be safely made by known frothing machines, wherein the frothing machine also mixes the powder into the liquid without causing the powder to settle into the coil of the stirrer, where it would hinder the rotation and cause the motor to burn out. Surprisingly, the cover device also blocks the formation of a vortex immediately above the stirrer, thereby improving the mixing of the powder and liquid.

[0013] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0014] Figure 1 A perspective view of a foaming machine is shown.

[0015] Figure 2 A perspective view of a stirrer is shown.

[0016] Figure 1A perspective view of a milk frothing machine is shown, which has a tank 1 with a generally circular outer and inner periphery for receiving milk to be frothed, and a handle 5. Below the lower surface of the tank 1, a magnetic drive device 2 is provided, which is suitable for applying a drive to an agitator or stirring device 3 located inside the tank without a mechanical connection passing through the wall of the tank 1. The agitator or stirring device 3 is supported on the bottom of the tank 1 to ensure that it remains in a central position and the drive mechanism can transmit the driving force to the agitator.

[0017] Below the bottom of the tank 1 is located a heating plate 4, which is suitable for heating the milk being used. The frothing machine has control means adapted to control the actuation of the heating plate and independently the actuation of the magnetic drive means. The control means may be a single ECU or a plurality of separate PCBs. The magnetic drive means may also have more than one speed so that the liquid does not froth, for example if a larger baby milk is being made.

[0018] In use, the control means is adapted to switch off the heating plate at a predetermined time before the agitator ceases to agitate, so that residual heat on the plate can be removed by the action of the agitator passing milk over it for that predetermined period of time. The length of time will depend on the size of the tank, the speed of the agitator and the desired temperature of the milk. Generally, the predetermined length of time will need to be around 10 seconds. The attraction of this particular arrangement is that it allows the milk to be heated to a higher temperature than would otherwise be possible, but when the milk is poured from the frother the bottom of the tank will have cooled sufficiently that any residual milk left in contact with the tank will not burn. For example, in the frother of the present invention, milk can be heated to 75°C, which is suitable for making hot chocolate, whereas in most prior art devices the milk is only heated to around 60°C, as any higher temperature would result in an unacceptable degree of milk burning on the surface of the frother.

[0019] Figure 2 An agitator according to the invention is shown. The agitator means 3 comprises an annular upright wall 7 connected to an axial spindle 9 by two radial arms 8. The spindle 9 extends above and below the radial arms 8. An agitator 10 is rotatably mounted on a rotatable drive shaft at the lower end of the spindle 9, the drive shaft being located inside the spindle 9. The radial arms 8 further comprise cover means 11 extending above the agitator 10 so that it substantially covers the agitator when viewed in a vertical direction from above. The cover means may be located about 5-10 mm above the agitator.

[0020] The cover device 11 prevents powder or flakes, such as chocolate powder, baby milk powder or cocoa powder, from being deposited on the coil of the stirrer 10. The cover device 11 protects the rotating stirrer 10 from chocolate flakes / powder while it is in use, as they tend to melt and thus clog the motor.

[0021] In use, the stirring means holds the stirrer 10 substantially concentric with the magnetic drive means located in the body. The stirrer 10 is held above the surface of the flat bottom, typically about 3 mm, thereby avoiding the stirring action from scratching the surface of the flat bottom. This allows the interior of the reservoir 1 to have a polished stainless steel surface or a non-stick coating. It also helps that the magnetic drive means operate 20-30 seconds after the heating element is turned off. This enables the milk to be heated to a higher temperature suitable for hot chocolate drinks. The heat is dissipated throughout the milk and does not burn on the bottom surface of the container.

[0022] The radial arms 8 and cover means 11 will also interrupt the vortex formed by the rotation of the stirrer, which is beneficial for producing better foam and increasing the working volume of the tank. The stirring device is also easy to disassemble and therefore easy to clean. This also ensures that the stirring device is safe in the dishwasher.

Claims

1. A frothing machine for producing a beverage, comprising a tank for receiving a liquid and a powder or flakes or cocoa powder to be mixed into the liquid, a magnetic drive device adapted to drive a detachable stirring device, the tank having substantially vertical walls and a flat bottom, the stirring device adapted to rotate in the liquid to mix and heat the liquid, the frothing machine further comprising a heating device adapted to heat milk or a milk-based liquid, the magnetic drive device being located outside the tank below the flat bottom of the tank, wherein the stirring device comprises a stirrer comprising a plurality of coils, the stirrer being mounted on a support member arranged to keep the stirrer away from the flat bottom, the stirring device further comprising a cover device, the cover device extending to substantially cover the space above the stirrer when the stirrer rests on the flat bottom, characterised in that The agitator has a width or diameter in a plane coplanar with the flat bottom, and the width or diameter of the cover device is substantially the same as or greater than the width or diameter of the agitator coil, thereby preventing powder or flakes or cocoa powder from being deposited on the agitator coil.

2. A foaming machine according to claim 1, wherein the support comprises an annular upright wall which, in use, rests on the flat bottom of the tank, the wall being connected to the axial spindle by radial arms, the support having a rotatably mounted agitator which can be rotated by a magnetic drive, wherein The supports hold the agitator off the flat bottom of the tank and the agitator is held in place by the stirring device rather than the magnetic drive.

3. A foaming machine according to claim 1 or 2, wherein the cover means is located about 5-10 mm above the agitator.

4. A hot chocolate making machine comprising a foaming machine according to any one of claims 1 to 3.

5. A baby milk maker comprising the foaming machine according to any one of claims 1 to 3.

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