Chapter 3 Functional descriptions
SMSO-2-02.03- 15.07.03 81
3.4.7 Milk drinks
Product serving:
Requirements:
Notes
A cup of hot milk.
Machine in operation, heated up, programmed to automatically serve hot milk.
Refrigerator operational, milk container filled, refrigerator temperature 3
o
C – 5
o
C (=optimum
temperature)
The description below contains only the processes involved in the process of conveying the milk. The
full process of steam generation is not described in detail here (see section entitled “Steam system (milk
drinks)”). The coffee filling process is not described in detail here. This process is described in the
“Brewing system (coffee)” section. See the section entitled “Components” in this chapter for detailed
functional descriptions of individual components (e.g. pump with bypass).
Milk dose:
The quantity of milk can be metered out in two ways:
Time controlled by the programming system
By programming the start and stop operation: the milk starts to flow out when the button is pressed
for the first time, and it stops when pressed a second time. (Timeout: If the button is not pressed a
second time after a certain period of time, the milk automatically stops dispensing.
Process
step
Control system (electronic/electrical) Hydraulic system
Product selection
1 The “milk” button is pressed.
The signal from the button panel reaches the unit control system;
the program analyses the command and starts the milk dispens-
ing operation.
Milk dispensed (assumption made: no milk product had been served for ten minutes prior to this operation)
2 Steam outlet valve opens, (power transistor connects
through).
Lifting magnet on ventilation valve switches on (power tran-
sistor connects through)
Solenoid valve opens and steam flows through the injector nozzle
into the foamer head. The foamer head is pre-heated. *)
The ventilation valve opens and prevents milk from being sucked
up while the foamer head is being heated.
3 Lifting magnet on ventilation valve switches off Ventilation valve closes after approximately two seconds of pre-
heating time.
4 Due to the under-pressure in the injector nozzle, milk is now
sucked through the milk pipe from the refrigerator. The milk is
heated and foamed a little.
The pressure in the steam generator reduces and water continues
to evaporate. In this way the temperature decreases and the water
level in the steam generator goes down.
See “Steam output (milk drinks)” for heating the steam generator, topping up the steam generator
Milk dispensing operation ends.
5 For programmed quantity of milk, just before the outlet time
has expired (= a few millilitres), or
For programmed start-stop operation, when the “milk” button
is pressed again, the following occurs:
6 Lifting magnet on ventilation valve switches on (power transistor
connects through)
The lifting magnet opens the ventilation valve. The pipe to the
foamer head is sucked empty through the steam output from the
injector nozzle.
7 Solenoid valves switch off
Steam outlet operation
Ventilation valve
The milk outlet operation stops
The ventilation valve closes the milk pipe; the milk that has been
sucked up as far as the ventilation valve flows back into the milk
container.
Another serving of milk.
Steps 1 – 7 are repeated
For a longer period with no serving of milk (other products served, or no products served at all)
The milk pipes need to be rinsed approximately 2 minutes after
the most recent product serving.
The rinse process is described in the section entitled “Rinsing the
milk pipes”.
The milk foamer housing is pre-heated only if no milk or milk
foam serving has been made during the last two minutes.
Otherwise the ventilation valve does not open and milk is ex-
tracted and heated immediately.
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