The present invention relates to a machine for the preparation of coffee and the like, and in particular a machine of the type termed professional, for use in bars and the like.
Conventional machines for the preparation of coffee typically comprise a hydraulic pump for supplying a flow of water coming from the mains water system, a boiler provided with a pressure switch and having a capacity which may amount to 10 liters or more, and at least one unit for the preparation and dispensing of the coffee, having at least one seating to which an associated filter-holder can be coupled. The internal volume of the boiler is predominantly occupied by water and, for the remainder, by steam. By means of an electrical resistance of the armoured type, the water and the steam in the boiler are maintained at a high temperature, of the order of 130° C. for example. The preparation and dispensing units receive hot water from the boiler and the level of the water in the boiler is controlled by means of a probe. A control unit operates the supply pump according to the signal supplied by the probe, so as to keep the amount of water in the boiler substantially constant.
In such conventional machines, at least one lance is generally provided for the emission of hot steam, and controlled by means of a suitable tap. The steam is drawn from the upper part of the region internal to the boiler.
In conventional machines it is further possible to dispense hot water, for example for the preparation of infusions and the like, by means of a pipe which is immersed in the boiler and which is controlled by a suitable tap.
In order to limit the formation of limescale in the hydraulic circuits and in the various components of the machine, it is necessary to provide a de-scaler and a softener.
In such conventional machines, the boiler represents the “heart” of the machine and any breakdown thereof generally results in the entire machine being inoperable.
The large mass of water which is maintained at constant temperature in the boiler entails a high consumption of electric power.
Moreover, on resuming operation after a period of interruption, such machines take a long time (of the order of several hours) to reach the thermal operating state. For this reason, a number of users leave such machines permanently switched on, which contributes to an increase in the consumption of electric power. If, on the other hand, the machine is switched off, for example at the end of the day, on resuming activity it is necessary to dispense and throw away a certain number of coffees before the quality of the prepared coffee reaches an acceptable level. In effect, the stagnation of the water in the boiler and in the pipes of the associated hydraulic circuits often entails the development of unpleasant tastes and/or odours in the first coffees dispensed on resuming activity.
Also known for the preparation of coffee are machines comprising a single boiler for each coffee preparation and dispensing unit, and a further boiler for keeping available heated water and steam which are dispensed on demand.
This solution makes it possible to modify the coffee preparation and dispensing capacity of the machine over time, according to need. Moreover, if the boiler associated with a specific coffee preparation and dispensing unit breaks down, it is possible to exclude that unit, while the rest of the units still remain operational.
However, the electrical consumption remains high, since the various accumulators associated with the individual units and the additional accumulator or boiler are in any case permanently heated.
In addition, this type of machine has a decidedly complex architecture and is particularly expensive to produce.
In the light of the above, it is an aim of the present invention to produce an improved machine for the preparation and dispensing of coffee, which machine makes it possible to remedy the drawbacks and limitations described above of the machines according to the prior art.