FR2742645A1 - Coffee preparation and distribution unit with simplified injector - Google Patents

Abstract

The unit includes a set of plastic components fixed to the lower plate (12) of the forward distribution head (11) of an expresso machine and supplied from an individual boiler (46) via a flexible hydraulic link (47) and electrically operated control valve (48). The set includes a cupholder (55) attached directly to the plate. The powdered coffee is placed in a strainer in a cup (56) with a long handle (57). The connections (65,66) to the control valve and to a hydropneumatic storage vessel (64) are made by preferably thermally insulating plastic tubes.

Description

 The invention relates to a multi-station coffee machine for preparing so-called "espresso" coffee, the hot water supply of each preparation station includes an individual boiler.

 The multi-station coffee machines targeted by the invention generally comprise a single boiler used for groups for preparing coffee and for producing hot water or steam delivered separately by a plunger head for the external needs of hot water and steam. .

 The water intended for each group follows a conduit which passes through a thermowell or a cartridge plunging into the body of the boiler.

 The boiler generally has as many cartridges as there are coffee preparation stations.

 The hot water then comes, after a possible thermostatically mixed with cold water, to supply each injection station.

 To do this, it passes through the mechanical parts constituting the actual preparation station and the support of the injection group to arrive at the desired temperature at the injection point.

 In addition to the cost arising from the mechanical complexity of the parts and their massive nature, traditional machines have the significant drawback of maintaining the water temperature at an optimal value during intensive use.

 The inertia of the metallic masses surrounding the water transport duct or inside which the water passes makes an unfavorable contribution to regulation.

 Indeed, if this thermal inertia makes it possible to obtain roughly satisfactory conditions for a permanent regime of average production in quantity and in rate, it is quite different during intensive use, as can be encountered in period of cutting edge in breweries, cafes, restaurants and other drinking establishments.

 Thus, in intensive use, that is to say continuously and at a high rate, the coffees successively prepared systematically become all hot after a certain number.

 Conversely, the production of coffee at the start of heating of the machine does not quickly find the optimal preparation conditions that may exist during the steady state.

 Some manufacturers have remedied this drawback by thermally insulating the massive connecting pieces between the boiler and each injection group or by making these hollow pieces to circulate the hot water from the boiler inside them. .

 Unfortunately, these modifications, both of them, bring only a small improvement.

 All these prior techniques have the significant drawback of delivering, at a certain moment in the regime of high rate of use of water, either too much or not hot enough at the injection stations.

 In fact, hot water transmits its calories to the massive parts of the boiler-injection group connection which, brought to a certain temperature by a greater flow of hot water, remain at a temperature close to this, because permanently heated. The water then becomes too hot at the outlet because its leaving boiler temperature is adjusted for an intermittent regime with heat losses on the path from the boiler to the corresponding injection group.

 Thus, in intensive use, the outlet temperature of the hot water proves to be too high to ensure, during its passage through the grind, optimal conditions for releasing the aromas necessary for the preparation of good coffee.

 This hot water transfer method does not guarantee, for the various conditions of use, the supply of quality coffee.

 To overcome this drawback, provision has been made to reduce, limit and regulate the temperature of the water supplied to the coffee injection groups in order to obtain, at the preparation level, water at an optimal and constant temperature. completely independent of the conditions of use, by a cold water mixing device placed on the pipe bringing the hot water from the cartridge to each injection station.

 This cold water mixing member comprises a main hot water channel and a cold water inlet mixed in variable quantity with hot water to deliver water at the desired temperature, lower than that of hot water. present at the cartridge outlet.

 This mixing member is preferably placed near the injection station and constituted for example by a thermostatic mixer with temperature limiter.

 According to another variant, the body of the mixer member is fully integrated into the injection group or the mechanical block connecting it to the boiler.

 If this previous solution constitutes an interesting compromise for coffee machines constructed in this way, the present invention also makes it possible to remedy the drawback of temperature variations, but more completely within the framework of circuits for preparing coffee. a whole new design.

 To this end, the invention relates to a multi-station coffee machine for the preparation of espresso type coffee comprising several coffee preparation stations, the water used for the preparation of coffee being heated by electrical means, a front pediment terminated downwards by a lower plate characterized in that each injection group of each coffee preparation station is supplied with hot water by an individual boiler hydraulically connected to the corresponding injection group by a flexible connection through a valve control and in that the injection group is composed of a succession of parts assembled forming an interior chamber and mounted on the lower plate of the front pediment, the connection ending in a branch supplying the injection group through the plate lower.

 The advantages of the present invention exceed the sum of the general advantages provided by each of the characteristics which constitute it.

 The simplicity of constitution and assembly of the group brings the advantages of cost reduction.

Individual instant boilers and flexible, thermally insulating hydraulic connections maintain the ideal temperature for the successive preparation of numerous doses of coffee.

Other characteristics and advantages of the invention will appear in the description which follows, given by way of nonlimiting example and accompanied by the drawings in which FIG. 1 is an overall perspective view.
showing the espresso machine according to
the invention with a broken boiler
individual and its associated circuit. Figure 2 is the general diagram of the water circuits
a classic two-group coffee machine
injection with mixer. Figure 3 is a perspective view of part
of a classic coffee machine showing the boiler
and its environment as well as the injection group
in the version with mixer on the circuit
hot water preparation. Figures 4 and 5 are sectional views in the state
dissociated from an injection group respectively from a
conventional machine and machine according
the invention; Figure 6 is a diagram illustrating a circuit
individual machine coffee preparation according to
the invention; . Figure 7 is a cross-sectional view of the
injection group; Figure 8 is a perspective view from the front
showing the part of the machine specific to a circuit
individual; . Figure 9 is a perspective view from the rear
showing the part of the machine specific to a circuit
individual.

 The present invention is intended to be applied to coffee machines 1 called "espresso" comprising several stations for example 2, 3, 4 for preparing coffee with corresponding injection group 5, 6, 7 such as that shown in the figure 1.

 It has a frame 8, with a lower plate 9 cup-to-cup holders such as 10 placed under the injection groups, a front pediment 11 with a lower base plate 12 traversed by the blocks of the injection groups which each support a leaching set.

 The machine also includes a frame 13 covered by a bodywork 14 and an upper plate 15 for maintaining the cups 16,17 in temperature at the upper part 18 as well as one or two spout (s) 19 and their control view of external needs for hot water or steam, for example for preparing infusions or for heating milk.

 Concerning the internal constitution of the machine, it has a central boiler 20 and a general water supply 21 comprising a water inlet with a main valve 22, a softener 23 and an injection pump 24. According to the invention, this boiler central 20 is connected only to (x) nozzle (s) -plunger (s) 19 through various safety and control devices (Figure 6).

 The central boiler 20 is the single boiler of the conventional coffee machine. It is used, in a conventional coffee machine, both for the preparation of hot water for coffee and for the production of hot water or steam for outdoor distribution.

 As can be seen in the diagram in FIG. 2 showing the circuits of a conventional machine with two stations, and in FIG. 3, the heating of the coffee preparation water is carried out in a single boiler 25 with immersion heater. heating 26 according to the principle of a water bath by means of cartridges 27, 28 plunging into the interior space of the boiler containing a larger volume of water kept under pressure at a constant temperature close to boiling.

 More particularly, the water inlet takes place through the main valve 22 and the water softener 23. The circuit is divided into a supply branch 29 of the boiler 25 comprising an isolation valve 30 and in a supply branch 31 of the circuits for preparing water for coffee through the injection pump 24 and two pipes for supplying cold water 32, 33 to the two hermetic heating cartridges 27, 28.

 According to the particularity of the circuit shown, the cold water conduits 32,33 each extend by additional branches 34,35 to thermostatic mixing members 36,37 also receiving on their main track by hydraulic connections 38,39 water heated by cartridges 27,28. Water is brought to the corresponding injection stations 40,41 by conduits through solenoid control valves 42,43. The coffee is poured into the cup (s) by a single or double pouring spout 44,45.

 According to the invention, the single boiler 25 of the prior machines is replaced by the central boiler 20 intended specifically for the production of hot water or steam for external needs other than the preparation of espresso coffee for example for tea or milk.

 According to one of the main characteristics of the invention, the machine comprises a plurality of individual boilers such as 46, specific to each preparation station 2,3,4, each connected to the corresponding injection group 5,6,7 by a connection flexible such as 47 to conduit made of flexible material, for example plastic, through a control solenoid valve 48 as can be seen in particular in FIG. 6.

 There are as many individual boilers 46 as injection groups. They are all supplied in parallel by the single injection pump 24. They are of the instantaneous and economical heating type enabling them to be discarded during a maintenance repair involving the boiler or during a clean operating fault. to the individual boiler.

 To better appreciate the differences with the invention and the simplifications brought by it, we will first examine in detail one of the injection groups of a conventional machine with reference to FIGS. 3 and 4.

 The conventional injection unit comprises a solid and metallic injection block 49 with a flat lower face provided with a central interface projection 50 shaped in the central part then machined in the mass of the injection block 49. On this projection 50 , which plays the role of a set of interface and injection and mechanical organ for the slight compaction of the grind, is reported a set of diffusion commonly called hand shower 51.

 The injection block 49 is a solid support 52, for example made of brass, connected by flange 53 to the rest of the circuit, support in which is drilled a duct 54 for supplying hot water to the shower through the central projection interface 50.

 The lower flat face of the injection block serves as a fixing support for a female part conventionally called cutter holder 55, that is to say a part with nut function on which a cutaway is fitted with quick release 56 with handle 57 intended to contain a strainer 58 in which the ground coffee is placed for leaching.

 The strainer 58 contained in the cup 56 is mounted on the central projection 50 allowing the ground coffee to be compacted lightly. The seal between the projection 50 and the strainer 58 is produced in the conventional version by a flat seal or in an original but known manner, by means of an O-ring 59 as shown in FIGS. 4 and 5.

 According to the present invention, the particularity of the injection group relates to the absence of the metal and massive mechanical support part 52, constituting the injection block 49, resulting in the direct fixing of the cutter holder 55 on the sub- face of the lower plate 12 of the front pediment 11 and the production of the central interface projection 50 in the form of an assembly of parts as will be seen below.

 The particularity of the injection group that the machine according to the invention comprises also relates to the direct connection of the water supply line to the interface and injection assembly and to the existence of a capacity hydropneumatic hydraulically connected to the interface and injection assembly.

 With reference to FIGS. 5 and 7, the injection and interface assembly of the machine according to the invention consists of the following individual removable parts present between the colander 58 and the underside of the lower plate 12 of the front pediment 11 .

 First of all, there is an injection piece 60 which transmits hot water to the coffee through the diffuser or hand shower 51. It has a front edge on which the hand shower is fixed, for example by a screw 61. On this front front open a plurality of longitudinal channels 62 for supplying water, the injection part of which is traversed, channels 62 in communication upwards with an upper annular distribution chamber 63 supplied with hot water by the flexible conduit of lead 47 and in hydraulic connection with a hydropneumatic capacity 64 through an intermediate part (FIG. 7).

 The hydraulic connections 65 and 66 existing on the one hand between the hydropneumatic capacity 64, the valve 48 and the injection group and on the other hand between the valve 48 and the injection group are also produced by flexible conduits, of preferably in thermally insulating plastic, the injection ends of which are connected to the interface and injection assembly by fittings 67, 68, for example on one threaded side and on the other with a fitting.

 This injection piece 60 also seals with the colander, for example by a peripheral groove 69, the lateral surface of which is lined with the O-ring 59 as it appears in FIGS. 4 and 5.

 The interface and injection assembly is fixed to the lower plate 12 by means of an intermediate piece called a spacer 70 ensuring the functions of spacer and of wall, in the form of a disc applied against the lower plate 12 on the underside of the front pediment 11 and fixed against this plate by a screw-nut couple passing through 71.

 This spacer 70 continues in the central part downwards by a section 72 internally threaded for the reception of the screw 61 for fixing the hand shower 51.

 These parts can be thermally stabilized at the optimum leaching temperature by a heating means, for example a thin electrical resistance (not shown), applied or fixed to the lower plate 12 in the mounting area of the injection group.

 The cup-holder part 55 is fixed, for example at three points by a screw-nut pair to the underside of the lower plate 12 of the underside of the front pediment 11.

 This constitution and this particularly simple detachable mounting and fixing method provide all the necessary mechanical solidity as well as various specific advantages specific to the maintenance and replacement of parts.

 The disc forming the spacer 70 is pierced right through with three conduits including a first central conduit 73 for the element for fixing to the lower plate 12 of the underside of the front pediment 11, a second eccentric conduit 74 for the injection of hot water and a last conduit 75, for example, but not necessarily, diametrically opposite the second conduit for the connection with the hydropneumatic capacity 64.

 These conduits communicate hydraulically with the annular distribution chamber 63 of the injection part then with the spray head via the distribution channels 62.

 Figures 4 and 5 illustrate the real simplification between the previous technique using large brass support parts connected by flange 53 forming the mechanical injection block 49 on which was fixed the cutter holder 55 and a constitution by a simple assembly of separable parts in accordance with the invention.

 In order to allow hot water to be obtained at constant temperature at the injection zone in the internal diffusion chamber 63 without suffering the drawbacks of the thermal inertia of the metal masses of the circuits and of the injection block, it is provided that each individual boiler supplying each coffee preparation station is of small capacity, for example one liter, and flexible distribution pipes made of thermally insulating plastic are provided up to the point of injection into the coffee. Similarly, the parts constituting the injection assembly are made of thermally insulating plastic.

 For the individual boiler, it is a so-called instantaneous small capacity boiler formed by a closed container 76 of small volume having at least one immersion heater heating element 77, a regulation sensor 78 associated with the control of the heating means. and a safety sensor 79 limiting the temperature below a value estimated as dangerous.

 This perfectly original combination of resources has become an industrial reality because it is possible to manufacture, at low cost, individual boilers of small capacity making it possible to envisage their complete replacement after use.

 In the coffee machine according to the invention, each coffee preparation station is functionally independent. It can be used alone, without using the full energy of the machine.

It is also possible to adjust a preparation station according to special operating conditions without disturbing the other stations.

 Each individual boiler 46 supplies an injection group by the simple flexible conduit 47 extended by its end 66 in thermally insulating plastic material through the control solenoid valve 48 to the point of injection into the coffee, that is to say -to say at the exit of the hand shower 51.

 The solenoid valve 48 has two channels including a return channel with evacuation by a discharge section 80.

 The use for these conduits of an insulating plastic material makes it possible to avoid a significant variation in temperature between that of the boiler outlet and the temperature at the injection point.

 The second important advantage of the invention relates to the great simplification of construction of the injection group.

 There are no longer any significant metal masses intended to provide the mechanical strength of the assembly.

 The cutter holder 55 on which the cutter 56 is mounted is strongly secured directly to the lower plate 12 of the underside of the front pediment 11.

 This fixing proves to be sufficient for the operations of locking or releasing the cup 56 on its cup holder support 55.

 We will now examine the hydropneumatic capacity 64 and its function in the hot water distribution circuit for the preparation of coffee.

 It is a container 81 of small capacity, preferably metallic in the form of a closed mini-carboy tightly connected to the distribution circuit at the level of the annular distribution chamber 63 of the injection part 60. .

 The interior volume of this mini-cylinder forming the hydropneumatic capacity is free but closed and waterproof, so that it acts like a hydropneumatic damper.

 She works in two different ways. In compression, it makes it possible to reduce the pressure surges coming from the injection pump 24 because the airtight interior volume filled with air acts as a pneumatic buffer during the instantaneous pressure increases at the start of the coffee preparation, generally consisting of a short initial premaceration phase, followed by continuous leaching. These two phases being separated by a slight dead time, the initial pressure gap as well as the subsequent rise in pressure are absorbed by the hydropneumatic capacity 64.

 The hydropneumatic capacity also works in expansion, which makes it possible when the injection pump 24 is stopped, while the capacity has been inflated by the leaching overpressure, to restore this energy to the circuit to drive out the unused water or a part of it towards the discharge through the control solenoid valve 48 passing towards the evacuation by a discharge conduit 80.

 Before explaining the operation, a general diagram of a "espresso" coffee preparation station will be described with reference to FIG. 6.

 After passing through the softener 23 which has an additional outlet for the central boiler 20, cold water is admitted into the injection pump 24, the outlet of which supplies each individual boiler 46 through an individual water meter 82.

 Each individual boiler is hydraulically connected to the corresponding injection group by the hydraulic link 47 comprising the three-way control valve 48 with discharge.

 All of the operation is controlled and managed by a ZP microprocessor from keyboards 83, 84 located on the front pediment 12 of the machine and information on the quantity of water provided in coded form by an individual water meter 82 in taking into account the values of the temperature sensor 78 of the individual boiler 46.

 During the operating cycle, the microprocessor yP acts on the injection pump 24 and on the control solenoid valve according to an internal program specific to the machine from commands received from the corresponding keyboard. It notably controls the heating of the individual boiler using the sensor 78 in order to maintain the water temperature at a predetermined constant value. It receives small or large dose commands from the keyboard.

 We will now describe an operating cycle on a coffee preparation circuit.

 The manual operating and dose selection commands on the keyboard keys start the operating sequence for the preparation of a dose of coffee sufficient for one or two cups.

 The sequence is as follows.

 The microprocessor zP records the commands then authorizes the opening of the solenoid valve 48 and the operation of the pump 24 whose water flow causes the operation of the water meter 82. The elementary values of quantity of water counted are transmitted by pulses to the microprocessor and recorded by it. When the quantity of water corresponding to the ordered dose is reached, the microprocessor stops the pump 24 and closes the main path of the solenoid valve between the boiler 46 and the corresponding injection group by simultaneously opening the path to the discharge conduit. 80.

 Hot water in the required quantity is loaded with coffee and fills the cup or cups placed under the group.

 After injecting the quantity of hot water into the coffee and lowering the pressure following the stopping of the pump 24, the water retained in the pneumatic capacity is emptied by decompression, through the terminal branch of the circuit, then is discharged through the control solenoid valve and the discharge conduit 80.

 The discharge thrust through the conduit 65 of the hydropneumatic capacity 64 ensures the evacuation of the residual water thus avoiding any mixing with the hot water of a new dose.

Claims (11)

 1. Coffee machine of the espresso type comprising several coffee preparation stations (2,3,4), the water used to prepare the coffee being heated by electrical means, a front pediment (11) terminated downwards by a lower plate (12) characterized in that each injection group of each coffee preparation station is supplied with hot water by an individual boiler (46) hydraulically connected to the corresponding injection group by a flexible connection (47) to through a control valve (48) and in that the injection group is composed of a succession of parts assembled forming an interior chamber and mounted on the lower plate (12) of the front pediment (11), the connection 47 is ending with a branch (66) supplying the injection group through the lower plate (12).  2. Machine according to claim 1 characterized in that each injection group receives on the one hand a first flexible hydraulic connection (66) coming from the individual boiler (46) through the control valve (48) and other share a second flexible hydraulic connection (65) coming from a hydropneumatic capacity (64).  3. Machine according to claim 2 characterized in that the hydropneumatic capacity (64) is a closed and sealed volume in hydraulic connection with the inner chamber of the injection group.  4. Machine according to claim 1 characterized in that each injection group consists on the one hand of two flexible material conduits, one (66) coming from the individual boiler (46) and the other (65) of a hydropneumatic capacity (64) and on the other hand of an assembly of parts terminated by a hand shower (51), assembly of parts replacing the central projection (50) present at the level of the central zone of the old support of the injection group and in that this assembly of parts as well as the cutter holder (55) are fixed on the lower plate (12) of the front pediment.  5. Machine according to claim 4 characterized in that the assembly of parts consists successively of a spacer (70), an injection part (60) and a spray (51) the latter two being maintained between them by a screw (61) and the spacer (70) being applied and fixed to the lower plate (12) of the front pediment (11) by a screw-nut assembly (71).  6. Machine according to claim 5 characterized in that the injection part (60) has a front front on which is fixed the spray (51), by the screw (61), front on which open longitudinal channels (62) extending on the other face by an annular chamber (63) supplied with hot water by the flexible conduits (65) and (66) by means of fittings (67,68) through the spacer (70).  7. Machine according to claims 5 and 6 characterized in that the spacer (70) continues downwards in the central part by a section (72) internally threaded for receiving the screw (61) for fixing the spray ( 51).  8. Machine according to claims 5 and 6, characterized in that the spacer (70) is pierced right through with three conduits including a first central conduit (73) for the element for fixing to the lower plate (12) front pediments (11), a second eccentric conduit (74) for the injection of hot water and a last conduit (75) for the connection with the hydropneumatic capacity (64).  9. Machine according to any one of the preceding claims, characterized in that the parts making up each injection group are made of plastic.  10. Machine according to claim 1 characterized in that each individual boiler is an instantaneous boiler.  11. Machine according to any one of claims 4 to 8 characterized in that an electrical resistance to maintain temperature is applied to the underside (12) of the front pediment (11) in the assembly area of the group.