Device and method for foaming a liquid foodstuff, in particular, milk

1. A device for foaming a liquid foodstuff, comprising:

a foaming chamber, a foodstuff feed line, a steam feed line, and an air feed line,

the foodstuff, steam, and air feed lines are connected in a fluid-conducting manner to the foaming chamber,

a solenoid air valve is provided for the air feed line that is controllable using a control unit, and

the solenoid air valve is an intermittent air valve in which at least one opened state with high air flow and one essentially closed state with at least one of a relatively lower air flow or no air flow is specified selectively by the control unit, and

the control unit and the solenoid air valve have an interacting construction such that, through repeated switching between the closed and open states of the solenoid air valve, an average air flow of the solenoid air valve is controlled by specifying at least one of a switching frequency in a range from 1 Hz to 50 Hz at which switching is performed between the at least two states of the solenoid air valve or a pulse-duty ratio between the at least two states for production of a specified foam product.

2. The device according to claim 1 , wherein the solenoid air valve and control unit are constructed such that a pulse-duty ratio between the opened state and closed state of the solenoid air valve from DC 2% to DC 80% is specifiable by the control unit.

3. The device according to claim 2 , wherein the control unit comprises a storage unit for storing at least one foaming mode, and the foaming mode comprises at least one of a switching frequency or the pulse-duty ratio.

4. The device according to claim 3 , wherein in the storage unit, the at least one foaming mode includes two different values for at least one of the switching frequency or the pulse-duty ratio, and a time period for its use is allocated to each value or each value pair.

5. The device according to claim 4 , further comprising a pump for feeding the liquid foodstuff connected in a fluid-conducting manner on a pressure side to the foodstuff feed line, the control device is connected to the pump and provides an interacting construction, such that a feed quantity of the pump is controllable by the control device, and the pump is a gearwheel pump.

6. The device according to claim 5 , wherein in the storage unit, the foaming mode also includes a foaming period for an entire foaming process, and the foaming mode also includes a foaming period and at least one feed output of the pump.

7. The device according to claim 6 , further comprising a steam generator that is connected to the control unit and has an construction interacting with the control unit such that the supplied quantity of steam can be controlled by the control unit.

8. The device according to claim 7 , wherein in the storage unit, the foaming mode also includes at least one of a quantity of steam or a time period for the steam feed.

9. The device according to claim 8 , wherein the air feed line is at least one of constructed or arranged such that air can be fed via the Venturi effect due to at least one of the steam flow, foodstuff flow or flow of a steam foodstuff mixture.

10. A method for foaming a liquid foodstuff, comprising:

providing a device for foaming the liquid foodstuff, including a foaming chamber, a foodstuff feed line, a steam feed line, and an air feed line and,

connecting the foodstuff, steam, and air feed lines in a fluid-conducting manner to the foaming chamber,

providing an air valve for the air feed line that is controlled by a control unit,

the air valve is provided for the air feed line that is controllable using the control unit, and the air valve is an intermittent air valve in which, the at least one opened state with high air flow and one essentially closed state with at least one of a relatively lower air flow or no air flow that is specified selectively by the control unit, and the control unit and the air valve have an interacting construction such that, through repeated switching between the closed and open states of the air valve, an average air flow of the air valve is controlled by specifying at least one of a switching frequency in a range from 1 Hz to 50 Hz at which switching is performed between the at least two states of the air valve or a pulse-duty ratio between the at least two states for production of a specified foam product and,

feeding the liquid foodstuff, steam, and air to a foaming chamber, the air being fed by an air feed line having an intermittent air valve, and

repeatedly switching the air valve using a control unit between at least one state with high air flow and one state with at least one of a relatively lower air flow or no air flow for controlling the average air flow of the air valve to produce a specified foam product.

11. The method according to claim 10 , further comprising during a foaming process, changing the air flow of the air valve according to a progression specified in the control unit.

12. The method according to claim 11 , further comprising feeding the liquid foodstuff using a pump at a feed rate specified by the control unit.