CONTROL METHOD AND DEVICE FOR DISPENDING A HOT FLUID Technical field

This invention relates to a control method aimed at monitoring any formations of limescale in a device for dispensing hot fluid, having the features of monitoring the limescale formations, in particular, but not necessarily limited to, for food products.

The invention also relates to a device for monitoring limescale formations in a device for dispensing a hot fluid.

Background art

The prior art systems for producing a hot fluid or for heating any liquid using a generic energy source traditionally use a boiler or a heat exchanger.

There are also devices for dispensing hot fluids not directly connected to the food products which can use the monitoring device according to the invention and the relative method. Hereafter, purely by way of a non- limiting example and to simplify the description, reference will be made to types of dispensing machines and/or dispensers for dispensing a hot fluid to obtain coffee or other hot beverages such as tea, camomile, herbal tea, etc. (that is to say, for dispensing hot fluids for food products), or for mixing the fluid in order to obtain food products such as soups or the like. As is known, a strongly felt problem arises from the formation of any limescale which forms in the heat exchanger, even taking all the necessary circumstances, for example due to extremely hard water or containing particular and unusual salts.

Any boiler or heat exchanger is subject to the formation, slow or fast, based on the water used, of a certain quantity of limescale which may make it impossible to dispense the fluid at the desired conditions.

It is difficult for a user realise about the formation of deposits which can even lead to the total occlusion of the passage of the water, which, in this case, can no longer be resolved by using special limescale removal products provided and which therefore means that the dispensing device must be sent for maintenance or replaced.

Any manufacturer of devices of this type recommend the use of special limescale removal products and, as they cannot know the hardness of the water which will be used and, consequently, the speed at which the limescale is formed and its consistency, require almost always excessive preventive limescale removal operations, corresponding to the most critical situations.

For the user, an unnecessarily frequent preventive limescale removal may prove to be inconvenient both in terms of unnecessary costs and loss of time.

If, on the other hand, the machine were to be sent for maintenance whilst still under guarantee, there could be disputes regarding whether or not the guarantee is applicable, as it cannot be demonstrated with certainty whether the fault is due to factory defects or incorrect maintenance by the user.

Patent document US 2001/0018866 illustrates a solution for monitoring the degree of limescale in a machine for dispensing hot fluids.

This solution comprises a differential membrane pressure device connected to an inlet and outlet fluid conduit. However, this system does not take into account the uncontrolled flow rate of the water which passes through the membrane under the various possible conditions of use and such as to obtain a data indication which is totally dependent on this flow rate with consequent poor practical value. In addition, the system is expensive since it results in a constructional complexity due both to the differential device and the two additional hydraulic connections to the system which inevitably translates into a poorly justified increase in the overall costs of the machine.

Aim of the invention The technical purpose of the invention is therefore to provide a control method and a dispensing device which are able to overcome the drawbacks of the prior art.

The aim of the invention is therefore to provide a control method and a dispensing device for a hot fluid which are able to constantly follow the formation of limescale during normal continuous use of the machine, which is precise and reliable at a limited cost.

The aim of the invention is therefore to provide a control method and a dispensing device for a hot fluid which is precise, reliable and inexpensive and which is are able to prevent the reaching of a total obstruction of the dispensing device, a total obstruction which, making it impossible to carry out any type of limescale removal, makes it necessary to replace the obstructed component.

The technical purpose indicated and the aims specified are substantially achieved by a control method and a dispensing device comprising the technical features described in one or more of the appended claims.

The dependent claims correspond to possible embodiments of the invention.

In particular, the technical purpose indicated and the aims specified are substantially achieved by a control method in a device for dispensing a hot fluid comprising the steps of monitoring a fluid passing through a boiler or heat exchanger of a dispensing device, identifying a degree of obstruction by limescale of the dispensing device and signalling to a user the need to perform a limescale removal if the degree of obstructing shown by said identification step is greater than a threshold value.

Moreover, the technical purpose indicated and the aims specified are, for example, substantially achieved by a device for dispensing a hot fluid comprising a source of fluid, for example a tank, a drawing and/or adjusting unit for feeding the fluid from the above-mentioned source or tank to a boiler or heat exchanger, a boiler or heat exchanger configured to heat the water drawn through the drawing and/or adjusting unit, a nozzle configured for dispensing the heated fluid from the boiler or heat exchanger and a control system configured for realising a method described above.

Further features and advantages of the invention are more apparent in the non-limiting description which follows of a non-exclusive embodiment of a control method and a dispensing device.

Brief description of the drawings

The description is set out below with reference to the accompanying drawings, which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 is a schematic representation of a dispensing device according to the invention;

- Figure 1a is a schematic representation of a different embodiment of the dispensing device according to the invention.

Detailed description of preferred embodiments of the invention With reference to Figure 1 , the numeral 1 denotes in its entirety a device for dispensing hot fluid, in particular, but without restricting the scope of the invention, for food products which, for simplicity of description, will hereafter be referred to as the dispensing machine 1.

Reference is made in this description to food products, but the method according to the invention and the relative machine may be used in various sectors in which it is necessary to constant control the presence of limescale formation.

Moreover, the term food products is used, by way of non-limiting example, to mean products such as coffee or other hot beverages such as tea, camomile, herbal teas, milk etc.

These food products may be loose or, for example, as shown in the accompanying drawings, contained in extraction pods or capsules "C" for preparing hot beverages such as coffee, tea, herbal tea and the like. In other words, the term extraction capsules "C" is used to mean, hereinafter, any generic type of capsule or dispenser or dispensing unit where the substance in powder, granular and similar form is placed.

The control method according to the invention is performed in real time upon every dispensing of the hot fluid.

The control method for dispensing a hot fluid according to the invention is therefore performed in a dispensing device 1 such as, for example, that shown in Figure 1. Hereinafter in this description reference will be made to water as a hot fluid, but it should be noted how other fluids can be used in the above-mentioned dispensing device 1 and which can form deposits in generic conduits.

The control method comprises a step of monitoring the fluid passing through a boiler or heat exchanger 4 of the dispensing device 1.

In this description, the term boiler or heat exchanger 4 will hereinafter be referred to simply as heat exchanger 4 for simplicity of description.

The monitoring step is performed in order to a degree of obstruction by limescale of the dispensing device 1. More specifically, the monitoring step is performed to identify the degree of obstruction of the heat exchanger 4.

If a value of the degree of obstruction is greater than a threshold value, the method comprises a step, preferably progressive, of signalling to a user the need to perform a limescale removal of the dispensing device 1.

In other words, the degree of obstruction is defined by the quantity of limescale accumulated in the heat exchanger 4 which is considered dangerous by the method, that is to say, by a control unit of the machine (which therefore requires a limescale removal signalled to the user) if, in the simplest case, it identifies a value greater than the above-mentioned threshold value.

If, on the other hand, the degree of obstruction were below the threshold value, the dispensing device 1 would continue to operate normally. Preferably, the monitoring step is performed by measuring a pressure Pm of the inlet fluid of the boiler or heat exchanger 4. The degree of obstruction described above is proportional to the value of the resultant pressure measured Pm, preferably corrected, if not constant and invariable, as a function of the fluid flow rate which passes through the system.

When the formation of limescale continues, the water passage sections will decrease proportionally, causing a progressive increase in the above- mentioned value Pm (it should be noted that in the absence of limescale this value Pm can normally be neglected and approximated to zero given the low resistance to the passage of the water offered by the heat exchanger 4; on the other hand, it could also be considered, for example by simply raising the values of the signalling and/or intervention thresholds).

In other words, this Pm value varies with the variation of the deposits generated by the limescale and is converted into a corresponding signal which will therefore increase with the increase in the formation of new deposits (or reduce as the latter decreases if limescale removal cycles are performed).

Preferably, as shown for example in Figure 1 , the monitoring method is performed with a pressure sensor 11 positioned in the inlet section of the heat exchanger 4.

The mere pressure difference is in any case linked in proportion to the flow rate of the fluid which passes through the heat exchanger 4.

Therefore, in order to have a correct value of the degree of obstruction it is necessary to divide the pressure jump by the flow rate of the fluid measured.

In the case of a system which also comprises measuring the amount of fluid dispensed, as in the specific case of hot beverages dispensing machines, it may be this measurement which provides in parallel also the above-mentioned measurement of the flow rate of the fluid.

In the case, on the contrary, of applications which do not initially use sensors from which to obtain this above-mentioned measurement of the flow rate of the fluid, the addition of the fluid would result in an increase in costs.

Alternatively, Figure 1a illustrates a very economical solution wherein a measurement of the pressure read by the inlet sensor 11 is performed close to a predetermined narrowing 15 created on the inlet conduit, so as to generate a corresponding partial Venturi effect.

With this feature, within a planned field of measurement, when, for example, an increase in the flow rate would result in an increase in the pressure read by the inlet sensor 11 , a corresponding partial negative pressure caused by the Venturi effect by the predetermined narrowing 15 can compensate for the above-mentioned increase, therefore making, at least within a planned field of measurement, the pressure read and, consequently, the corresponding estimation of the limescale accumulated, practically independent of the speed of dispensing the fluid.

Preferably, in the specific case of hot beverage machines, the monitoring step is performed by measuring, only in a first - short - initial step of dispensing, this infeed pressure of the fluid into the heat exchanger 4.

In fact, during the initial steps, the fluid which passes through the food powder still dry will not find any significant resistance, making it unnecessary to measure the outfeed pressure since it will be close to 0; will therefore be convenient to use with this feature only the pressure sensor 11 in the inlet section of the heat exchanger 4 to reduce the costs of the system.

In the case of different use, where the fluid is dispensed at ambient pressure, the detection may also not be limited only to the initial step but will continue for the entire dispensing.

According to a different embodiment, and advantageously, the monitoring in just the above-mentioned initial dispensing step (as also in the above- mentioned case of continuous backpressure equal to 0) may be performed by comparing a real performance of a unit for feeding the fluid, such as, for example, a pump 3, with reference performances of the pump 3, preferably used at reduced and stabilised performance levels.

In fact, a specific pump 3 may have, as a function of the energy with which it is supplied, a well determined dispensing curve on the basis of which the flow rate of liquid supplied starts from a maximum value when there is no counterpressure flowing out to gradually fall to 0 when reaching the maximum pressure which it is able to dispense in these supply conditions.

It should be noted that the above-mentioned dispensing curve is normally also a function of the temperature of the pump (the electromagnetic vibration pumps commonly used heat considerably, so much so they are only suitable for intermittent and non-continuous use).

In fact, the copper making up the respective internal windings increases, with the increase in temperature, its resistance, consequently reducing the absorbed current and hence the performance which can be achieved.

For this reason, for a particularly accurate assessment, it will be preferable to also measure and consider in the calculation the current absorbed by the pump under those operating conditions.

In other words, the monitoring is performed on the basis of the counterpressure which can be calculated, with good precision as the dispensing curve from the pump 3 is known, possibly also corrected for temperature, as a function of the flow rate of the fluid: since a measuring device is interposed between the pump 3 and the tank 2, that is to say, for example, a turbine 9, which is able to quantify the fluid supplied to the pump 3, the turbine 9 can equally measure the speed and therefore, in parallel, the above-mentioned flow rate.

In other words, if there are no encrustations, the initial dispensing will occur at practically zero counterpressure and, consequently, at the maximum speed or flow rate planned in those conditions; on the other hand, the presence and the increase in limescale formations, causing a progressive increase in the counterpressure downstream of the pump, will cause a corresponding gradual reduction in the speed or flow rate measured by the turbine 9 which will therefore provide the corresponding degree of obstruction of the dispensing system.

Preferably, the method may also initially comprise a step of progressive signalling the limescale formations (for example, a warning light which, initially switched off below a predetermined threshold, starts to flash with an on/off ratio proportional to the degree of obstruction until remaining ON when a second predetermined maximum threshold is reached).

Preferably, the method may also comprise a step of locking the dispensing device 1 in such a way as to avoid exceeding a predetermined maximum value of the degree of obstruction.

In other words, following repeated progressive signalling steps the method may comprise a block of the dispensing device 1 until the user carries out a limescale removal.

Preferably, the method may also comprise a step of identifying a possible false limescale removal of the dispensing device. This step therefore also comprises, after the above-mentioned block of the dispensing device 1 , a block of the limescale removal procedure following a predetermined number of monitoring operations identifying false limescale removal attempts by the user.

In other words, if a user were to use an ineffective limescale removal product, or, on the other hand, decided to “trick" the dispensing device 1 , leaving water to circulate without limescale removal product, the method would be able to identify that after the planned signals there is still the same degree of obstruction (if not greater) and to take into account the number of times in which this phenomenon occurred.

After exceeding a predetermined number of attempts which have occurred without success and/or with a worsening of the degree of obstruction detected, the method could therefore prevent further attempts to avoid reaching a possible total occlusion. In this way, if the machine were to enter a maintenance status it would be possible to understand with certainty, by simply observing this total block, that inadequate maintenance has been carried out by the user.

Consequently, the maintenance may be limited to removing, possibly by simply providing a sequence of commands unknown to the public, the blocking of the limescale removal cycles which can be performed again in the correct manner in the maintenance operation itself, without involving any additional costs for disassembling and replacing components. Advantageously, the method described above makes it possible to overcome the drawbacks of the prior art, signalling to the user with suitable precision and progressively the need to perform a limescale removal.

Moreover, the method allows one to understand if a fault is due to defects of the dispensing device 1 or is due to failings by the user.

The invention also relates to a dispensing device 1 for hot fluids for food products which comprises a source of the liquid to be dispensed, such as, for example, a tank of water 2.

A drawing unit 3 (for example a pump) configured to draw water from the tank 2.

A heat exchanger 4 configured to heat the water drawn by the pump 3.

A nozzle 5 configured to dispense the water heated by the heat exchanger 4.

A source of energy E at least for supplying the pump 3 and the heat exchanger 4.

The dispensing device 1 may also comprise a turbine 9 (or similar measuring device) interposed preferably between the pump 3 and the tank 2 and configured for measuring with a desired precision the quantity and/or the flow rate of fluid/water fed to the pump 3 (and consequently to the heat exchanger 4).

The dispensing and adjustment device 1 also comprises a control system 6 configured for implementing a control method as described above. The term "control system 6" means all those hardware and software components (that is, the control electronics) which allow the method described above to be implemented.

Preferably, the control system 6 may comprise a first pressure sensor 11 positioned in an inlet portion of the heat exchanger 4 for monitoring an inlet pressure of the fluid in the heat exchanger 4.

This solution may be used to perform the monitoring step to identify the degree of obstruction by limescale in which the inlet pressure of the fluid in the heat exchanger 4 is to be measured only during the first dispensing step, or in systems which comprise dispensing without appreciable counter-pressures at the outlet.

This solution is particularly advantageous in order to identify the degree of obstruction by limescale by monitoring the pressure at the inlet of the fluid, but a precise assessment must also consider the flow rate of the fluid. Preferably, the system can simply assess the flow rate of the fluid dispensed by the pump, preferably supplied at reduced and/or stabilised power, at the start of the dispensing; preferably, for a greater precision, the system can in this case also measure and assess the current absorbed by the pump. Advantageously, the device described above makes it possible to implement the method described above in such a way as to prevent any unnecessary limescale removal by a user.

Advantageously, the device described above makes it possible to implement the method described above in such a way as to identify whether any fault occurs due to the user.