Machine with piloted limescale precipitation system and related method

Abstract

A coffee machine is described, equipped with a 5 boiler (1) of the single-boiler type and a coffee dispensing circuit, wherein heating means (5) produce hot water and steam in a boiler body (1) and, through one or more heat exchangers (7), heat water that flows through the coffee dispensing circuit, heating occurring through the passage of the water that is pumped inside the heat exchangers (7) through an injector (8) and then sent through a dip tube (10) and a pipe (13) to a coffee dispensing system (14) comprising a filter holder with relative filter and a thermostatically controlled dispensing group (15) for dispensing coffee, the coffee machine having means suitable for causing the controlled precipitation of the CaCO3 limestone contained in the water with which to prepare coffee.

Description

[0001] MACHINE WITH PILOTED LIMESCALE PRECIPITATION SYSTEM

[0002] AND RELATED METHOD

[0003] The present invention refers to a coffee machine equipped with a boiler of the single-boiler type and a coffee dispensing circuit, with a controlled limescale precipitation system and a thermostatically controlled coffee dispensing group .

[0004] Boilers of the single-boiler type include a service boiler in which hot water is present in liquid phase, in equilibrium with its own steam. These fluids also heat the water for coffee through heat exchangers placed inside it.

[0005] The water supply and withdrawal circuit for coffee takes place from the "cold" part of the heat exchanger, to minimize the formation and subsequent deposit of limescale in the coffee dispensing circuit. The infusion temperature is regulated in the dispensing group via an electrical resistance and relative temperature sensor.

[0006] The coffee circuit includes as many heat exchangers as there are dispensing groups installed on the machine .

[0007] The heads of these exchangers are welded to the shell of the service boiler while their bodies are immersed in it , and are positioned with the main axis directed from bottom to top . In this way, a strati fication is created by exploiting the high heat exchange that is generated in the part of the exchanger immersed in the steam area of the service boiler and the lower heat input relative to the part of the exchanger that is generated in the part of the exchanger immersed in water .

[0008] Water enters the exchanger and is subsequently withdrawn using two coaxial pipes which make maintenance extremely easy and which enter and exit the exchanger from the lower part , which is also the least hot .

[0009] With this circuit , it is possible to separate the pressure ( and therefore the temperature ) of the steam in the service boiler from the cof fee production pressure even when using only one boiler ( single-boiler machine ) .

[0010] By taking water for the cof fee circuit from the part of the exchanger where water is less hot , the formation and subsequent deposit of limescale in the water pipes for the cof fee is reduced, but not eliminated .

[0011] Documents EP-A2- 0 393 385 and DE-A1-26 38 380 disclose cof fee machines with inj ectors according to the prior art .

[0012] Obj ect of the present invention is inducing a controlled precipitation of limescale in order to avoid the deposition of limescale in cof fee water pipes .

[0013] The above and other obj ects , as will be explained below, are achieved with a cof fee machine and a method as disclosed in the respective independent claims .

[0014] The cof fee machine is equipped with a boiler of the single-boiler type and a cof fee dispensing circuit , in which heating means produce hot water and steam in the boiler body and, through one or more heat exchangers , heat water that passes through the cof fee dispensing circuit , the heating occurring through the passage of water that is pumped through an inj ector inside the one or more heat exchangers where a piloted precipitation of CaCOs occurs , and then sent through a pipe to a thermostatically controlled group in which there is a filter head for dispensing cof fee , with which to prepare cof fee .

[0015] The method for controlling the precipitation of limescale in cof fee machines provides that the inj ector inj ects cold water into the hottest point of the exchanger so that water becomes depleted of CaCOs which precipitates on the hot parts of the exchanger, the hot parts of the exchanger being distant from the outlet of the inj ector, which is a colder point than the walls of the exchanger .

[0016] Preferred embodiments and non-trivial variations of the present invention form the subj ect matter of the dependent claims .

[0017] It is understood that all attached claims form an integral part of this description .

[0018] The invention solves the problems in question as limescale is deposited in areas of the cof fee circuit far from the critical points , in particular the inj ector outlet , and therefore does not constitute an obstacle to the correct functioning of the machine .

[0019] It will be immediately obvious that countless variations and modi fications can be made to what i s described ( for example relating to shape , dimensions , arrangements and parts with equivalent functionality) without departing from the scope of the invention, as appears from the attached claims.

[0020] The present invention will be better described by some preferred embodiments, provided by way of example and not by way of limitation, with reference to the attached drawings, in which:

[0021] FIG. 1 shows the diagram of the service boiler and heat exchangers;

[0022] FIG. 2 is a cross-section of the coffee machine with a coffee dispensing group highlighted.

[0023] With reference to FIG. 1, (1) indicates the service boiler body, inside which there is water in the liquid phase (2) in equilibrium with the vapour phase (3) , the two phases being separated by a free surface ( 4 ) .

[0024] Water inside the boiler body (1) is kept at a temperature preferably varying between 100°C e 130°C through an electrical resistance (5) driven by a temperature sensor (not shown) .

[0025] Inside the boiler body (1) there are one or more heat exchangers (7) which essentially consist of tubes welded to the boiler body (1) . Inside each tube (7) and coaxial thereto, there is a tube (8) having a small diameter. The tube (8) is hydraulically connected in the lower part with a intake (9) for cold water and ends in the upper part of the exchanger (7) . Reference (6) designates liquid inside the exchanger (7) which, during the mixing phase, homogenizes the temperature, facilitating the heat exchange between the walls of the exchanger (7) and the high temperature heat source contained in the boiler (1) but outside the tube (7) , transmitting heat by convection to the fluid (6) inside the heat exchanger (7) , just above the free surface (4) , used to inject cold water into the exchanger (7) .

[0026] In the lower part of the exchanger (7) , there is a suction pipe (10) , that is, an annular conduit which connects the exchanger (7) with a water intake (11) , from where the heated water can be taken .

[0027] The cold water, taken from the intake (9) , flows through the injector (8) and exits from the upper end of the injector (8) , mixing with the hot water (12) already present in the tube (7) . The heated water flows through the annular duct (10) , is taken through the intake (11) and, from here, along a pipe (13) reaches a thermostatic group (14) where there is a thermo-stated delivering assembly (15) with a resistance (16) . Reference (14) designates the coffee delivering system because, as shown, it also comprises the filter-holder with related filter for dispensing coffee (FIG. 2) . The regulation of the temperature to the optimal value for preparing the infusion is obtained with an electrical resistance (16) and a suitable temperature sensor (not shown) .

[0028] Coffee preparation takes place according to the following steps.

[0029] Step 1 - Cold water inlet / inj ection

[0030] By means of a pump (17) , water is pumped, through the injector (8) , inside the heat exchanger (7) . The pump (17) also performs the task of sending water to the thermo-stated delivering assembly (15) at the optimal pressure to prepare the infusion.

[0031] The injector (8) is inserted from the lower part of the heat exchanger (7) and extends for almost the entire length of the exchanger (7) itself, so as to inject water into the hottest part of the exchanger (7) . The injector (8) is coaxial with the heat exchanger (7) so as to always be located at the point furthest from the walls and therefore the coldest. In fact, heat is transmitted by the external walls of the exchanger (7) which are in contact with the fluid contained in the boiler body (1) which, at the height where cold water is injected, is in the vapour phase.

[0032] Step 2 - Controlled precipitation of limestone

[0033] Water injected into the hottest point of the exchanger (7) , due to temperature, pressure and low speed, becomes depleted of CaCCt which precipitates on the hot parts of the exchanger (7) . These hot parts are distant from the outlet of the injector (8) which is a colder point than the walls of the exchanger (7) . The decalcification process takes place throughout the journey that the water makes between the outlet of the injector (8) and the entrance into the dip tube (10) ; in particular, this phenomenon occurs in the section of the exchanger (7) immersed in steam by virtue of the better heat supply that the steam releases to the walls of the tube (7) , compared to what happens in the lower part immersed in hot water. When the injected water reaches the proximity of the inlet of the dip tube (10) it is depleted of CaCCh which is below the limit concentration for precipitation and therefore, given these thermochemical conditions of pressure and temperature, the precipitation process is blocked or at least reduced in speed. Step 3 - Mixing

[0034] During the descent of water from the hot part to the cold part of the exchanger (7) , by means of one or more small holes on the injector (8) , of a diameter preferably greater than or equal to 1 mm (not shown) , cold water passes from the injector (8) to the dip tube (10) , where it mixes with part of the untreated cold water, thus reducing the temperature of water intended for coffee.

[0035] Step 4 - Exit from the exchanger

[0036] The decalcified water then exits the heat exchanger (7) and is pushed towards the delivering system (14) for coffee dispensing. The exit from the exchanger (7) occurs coaxially with the injector (8) allowing a further lowering of the water temperature which, by cooling further, reduces the risk of limescale deposits.

[0037] Step 5 - Temperature-controlled delivery

[0038] The low temperature of the water coming out of the heat exchanger (7) must be increased to optimal values for coffee dispensing and this is achieved by means of the resistance (16) placed in the coffee delivering system (14) , which is located outside the body of the machine.

[0039] The adoption of the resistance (16) allows managing the coffee dispensing temperature independently from the working temperature of the service boiler (1) . In this way, it is possible to optimize / reduce the size of the service boiler (1) by acting on its working pressure / temperature without losing performance during the steam dispensing steps.

[0040] The coffee delivering system (14) is therefore a thermal unit independent from the service boiler (1) and can be regulated through the electronics group by group, without hydraulic interventions on the water supply circuit.

[0041] The adoption of a "single-branch pipe" and not a "ring"-type coffee circuit allows not using mechanical flow reducers (gigleur) to balance the coffee water delivery temperature to the dispensing group along the coffee circuit itself, with the advantage that in this way less maintenance is required .

[0042] Due to the adoption of a "single-branch pipe" circuit, the measurement of the amount of water dispensed in the single coffee group can be done both before entering the exchanger (7) (cold water) and after exiting the exchanger (7) (hot water) .

Claims

CLAIMS1. Coffee machine equipped with a boiler (1) of a single-boiler type and a coffee dispensing circuit, in which heating means (5) produce hot water and steam in a body of the boiler (1) and, through one or more heat exchangers (7) , heat water that passes through the coffee dispensing circuit, heating occurring through a passage of water that is pumped inside the one or more heat exchangers (7) through an injector (8) and then sent through a dip tube (10) and a pipe (13) to a coffee dispensing system(14) comprising a filter holder with related filter and a thermostatically controlled dispensing unit(15) for dispensing coffee, the coffee machine having means suitable for causing the controlled precipitation of the CaCCt limestone contained in the water with which to prepare coffee, wherein the means suitable for causing the controlled precipitation of the CaCCt limestone contained in the water with which to prepare coffee, comprise the one or more heat exchangers (7) and the injectors (8) which inject cold water into the hottest area of the exchangers (7) , so that the heating of water causes a precipitation of limestone on the hot parts of the exchanger (7) ;- the outlet of the injectors (8) is positioned as far as possible from the hot parts of the one or more exchangers (7) ; the one or more heat exchangers (7) and the injectors (8) are coaxial, and the coffee machine has a small hole on the injector (8) , suitable for hydraulically connecting it with the dip tube (10) , so that a passage of cold water from the injector (8) to the dip tube (10) allows the temperature of the water intended for coffee to be reduced.

2. Coffee machine according to claim 1, characterised in that the hole on the injector (8) has a diameter greater than or equal to 1 mm.

3. Method for controlling the precipitation of limescale in coffee machines according to at least one of claims 1 to 2, characterised in that the injector (8) injects cold water into the hottest point of the exchanger (7) so that water becomes depleted of CaCCt which precipitates on the hot parts of the exchanger (7) , the hot parts of the exchanger (7) being distant from the outlet of the injector (8) , which is a colder point than the walls of the exchanger (7) .

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