WO2010079116A1

WO2010079116A1 - Method for supplying a volume of a hot beverage

Info

Publication number: WO2010079116A1
Application number: PCT/EP2009/068041
Authority: WO
Inventors: Vincent Grenon; Luis Duarte
Original assignee: Gotec Sa
Priority date: 2009-01-08
Filing date: 2009-12-30
Publication date: 2010-07-15
Also published as: CH700233A2; CH700233B1

Abstract

The invention relates to a method for supplying a volume of a hot beverage, comprising the following steps: a) opening a liquid intake valve (4) for enabling a liquid to enter a heating cylinder (2); b) longitudinally moving a piston (3) in a first direction in said cylinder (2) in order to draw the predetermined liquid volume into the heating cylinder (2) through said intake valve (4); c) closing said intake valve (4) and opening a discharge valve (5); d) longitudinally moving said piston (3) in a second direction opposite to the first one in the cylinder (2) in order to expel through said discharge valve (5) at least a portion of the heated liquid out of the cylinder and to wet a powder; e) waiting for a predetermined duration; f) longitudinally moving the piston (3) in the first direction in said cylinder (2) so as to reduce the liquid pressure in the powder; g) longitudinally moving said piston (3) in the second direction in said cylinder (2) in order to expel the liquid through said discharge valve (5) and through the powder in order to provide said volume of hot beverage.

Description

Method for delivering a volume of hot drink

Technical area

The present invention relates to a method for delivering a volume of hot drink with a volumetric liquid pump including a heater body, and a pump adapted to the implementation of the method.

State of the art

[0002] Numerous examples of liquid pumps operating according to different principles are known. There are also different types of water heaters. Many coffee machines use a tank in which the water is preheated before being pumped through the coffee powder and then poured into the cups. These devices require preheating a larger volume of water than that which will eventually be used, which causes energy waste. When, conversely, a volume of coffee is required that is greater than the capacity of the tank, it is necessary to wait after filling until the newly introduced water has been heated.

Also known continuous liquid heating devices in which the water is heated during its passage in a tube or pipe. Such devices are described for example in the patent application EP-A1 -1380243 (Nestec SΑ) which illustrates a liquid heating module comprising a hollow tube coated with at least two heating resistors, for example wires or conductive inks deposited on a substrate. A similar solution is also described in EP-A1 -1097663.

The solutions of the prior art generally require a pump for circulate the water in a heating tube or thermoblock, and a flow meter to control the amount of water supplied. The complete device thus comprises many discrete partsdistinctes, complex to combine, and whose assembly requires a large volume. Moreover, the temperature of the water depends on both the electric current in the heating module and the flow rate of the water in the tube, which requires a fairly complex regulation.

The patent application FR2780262 discloses a coffee machine comprising a hollow piston pump driven by an electromagnetic motor. The hollow piston traversed by the liquid is difficult to clean; in addition, it does not allow to move a constant volume of water with each actuation. A flowmeter is therefore required, formed in this case of a crazy wheel with blades rotated by the flow of liquid.

Other examples of hot beverage dispenser comprising a piston pump are described in patents US2654505 and FR2012636.

The patent application EP-A1 -496939 discloses another pump for a coffee machine comprising a piston sliding in a cylinder actuated by a motor and an actuator. The stroke of the piston, which determines the volume of liquid sucked and then rejected into the cylinder, is controlled using microconnectors or an encoder connected to the engine. The signals from the microswitches or the encoder are processed by electronics that generate control signals for the motor. The volume of water in the cylinder is heated using a resistive wire wound around the outer surface of the cylinder and traversed by an electric current.

This arrangement makes it possible to heat the liquid directly inside the pump, so that an additional heating tube is not required. Moreover, the use of a piston pump makes it possible to easily control the volume of liquid aspirated, simply by modifying the stroke of the piston. However, the time it takes to get a cup of hot coffee is important for several reasons:

First, the tube is heated using a discrete wire wound around the cylinder. Only a part of the heat emitted by the wire is transmitted to the cylinder and then to the liquid; the rest is dissipated in the air. The thermal resistance between the wire and the cylinder is indeed important, unless expensive measures, for example the use of an electrically conductive paste, are implemented.

On the other hand, the heating of the cylinder begins only when it is full of liquid. The significant thermal inertia of the heating wire and the cylinder slows the heat transfer and increases the time required to heat the volume of liquid sucked. This inertia also makes it difficult to accurately maintain a constant temperature of the liquid; the reaction time of the system is too important, especially when the external conditions change, for example during the evacuation of the liquid. In addition, due to the high thermal inertia and the thermal resistance between the wire and the cylinder, the system remains hot for a relatively long time even when the electric current is interrupted.

It has been discovered in the context of this invention that the quality of a coffee or strongly depends on the temperature of the water passing through the powder. Indeed, a temperature too low does not allow water to carry all the aromas of coffee. A precisely controlled and constant temperature throughout the flow through the powder can significantly improve the quality of coffee obtained.

The quality of coffee also depends on the speed at which the liquid passes through the coffee: too fast flow does not allow the liquid to carry all the aromas, while a too slow flow may cause the dissolution of undesirable parts of the grain. Moreover, a successful coffee depends on the pressure of the liquid through the powder.

Ordinary coffee machines do not allow precise control of these different parameters. For example, the water temperature only reaches approximately the ideal setpoint temperature; this temperature also varies considerably between the beginning and the end of the expulsion of the liquid.

On the other hand, these parameters are not entirely independent of each other. For example, the flow rate depends on the pressure of the liquid. The temperature decreases if the flow rate is too slow. It is therefore extremely difficult to obtain the ideal values for each of these parameters with a coffee machine or a conventional liquid dispenser.

Brief summary of the invention

An object of the present invention is to provide a method for delivering a volume of hot beverage that does not have the disadvantages of the above methods.

Another object is also to provide a device for carrying out this method and to independently control the temperature of the water throughout its expulsion, the flow rate and the duration of wetting of the powder , as well as the pressure of the liquid.

According to the invention, these objects are attained in particular by means of a method comprising the features of the main claim, and with the aid of a pump comprising the features of the claim. independent of device. Preferred but non-essential embodiments are indicated in the dependent claims and in the description.

Brief description of the figures

Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

[0019] Figure 1 illustrates a perspective view of a pump according to the invention.

[0020] FIG. 2 illustrates a sectional view of a pump according to the invention, represented without the motor element.

Figure 3 is a block diagram of the system.

Example (s) of embodiment of the invention

An example of a pump according to the invention is illustrated in Figure 1. The pump comprises a cylinder 2 of cylindrical section in this non-limiting example. A piston 3 can slide inside the cylinder, being moved by a motor element 1. A liquid coming from a tank not shown or from a source of liquid not shown can enter the internal volume of the cylinder by a valve 4 or 5 valves can be controlled electromechanically by actuators, mechanically by the movements of the piston, or opened and closed automatically depending on the differences in pressure between the inside and the outside of the cylinder.

RECTIFIED SHEET (RULE 91) ISA / EP The motor 1 is preferably an electric linear actuator capable of moving alternately in one direction and then in the other when an electric current is supplied thereto. According to a preferred feature of the invention, the motor can be powered at 12 or 24 volts, or at a lower voltage, which allows it to be used in an automobile with the current produced by a battery. Other DC or AC voltage sources are also conceivable within the scope of the invention. Rotary motors with a worm, cam, connecting rod or toothed belt system for converting rotation into a translation, or pneumatic cylinders can also be employed.

In a preferred embodiment, the stroke of the piston can be controlled to vary the amount of liquid sucked by the valve 4 and then expelled via the valve 5. The stroke is preferably controlled by a microcontroller by changing the duration of supply of the motor 1. The control can be carried out in an open circuit, that is to say by applying a pulse duration which depends solely on the set value chosen for the stroke and the volume, or preferably in circuit closed with a feedback loop taking into account a measurement value provided by a position sensor 6. The position sensor may comprise for example one or more Hall effect sensors, or an encoder, connected to the movable shaft of the motor 1.

The piston comprises a piston head provided in this example with two peripheral seals 30, 31 each engaged in an annular groove at the periphery of the piston head. The joints 30, 31 are for example o-ring joints and are slightly compressed against the inner face of the cylinder. Other joint geometries, different from the o-ring, can also provide the sealing function. A lubricant 32, for example a food compatible grease, is trapped between the two joints, the outer surface of the piston and the inner face of the cylinder in order to lubricate the piston and facilitate its movements. The cylinder is preferably made of metal, for example stainless steel or another material good thermal conductor. Its outer faces are at least partially covered with electrical tracks 70, 71, .. forming part of an electric heating circuit 7; the tracks have an electrical resistance that can produce heat when a current flows through them. In a preferred embodiment, the tracks 70, 71 consist of conductive ink electrically deposited in thin layers by screen printing or by another printing process on the outer surface 20 of the cylinder 2. In fact, it has been found that Surprisingly, this process makes it possible to print sufficiently thick and resistant layers so as not to be destroyed by the large currents necessary for heating the water - even if the supply voltage is reduced, for example 12V or 24V DC.

The electric circuit constituted by the tracks preferably comprises several branches 70, resp. 71 connected in parallel, which reduces the current in each branch. Electrical switches 72 resp. 73, for example transistors, integrated circuits or relays, make it possible to modify the configuration of the circuit and to control the branches which are supplied with current and which contribute to the heating of the cylinder and the liquid in the cylinder. These switches may be provided on the surface of the cylinder, or more easily in the electronic circuit which supplies the current to the different branches of the circuit.

In a preferred embodiment, the electric heating circuit 7 comprises at least two branches 70, 71 which occupy or cover distinct longitudinal portions of the cylinder. It is thus possible to choose the longitudinal portion of the cylinder which is heated at each instant by selecting the branches 70 or 70 + 71 supplied with current. Thus, a number of branches will be fed depending on the amount of volume to be heated, so as to avoid large portions of the cylinder above the upper stroke limit of the piston. In one for example, only the lower half of the cylinder is heated with the branch 70 when a desired produces a half volume of hot water cylinder. The number of heating tracks 70, 71 may be greater than two.

The choice of the number of branches supplied with current may also depend on the temperature of the desired liquid. In general, the heating power, and therefore the time required to obtain a given liquid temperature, can be controlled by acting on one or more of the following parameters:

• Number of branches 70, 71 of the circuit supplied with current

• Branch connection between them (series, parallel, etc.)

• Duration of the current in the various branches 70, 71. It is possible to feed certain branches longer, or differently, than others.

• Intensity of the current in each branch, or modulation of this intensity as a function of time.

The choice of the above parameter or parameters depends on the volume of liquid to be heated and the set temperature introduced with a control circuit 12, and possibly the initial temperature of the cylinder if it is known. A temperature sensor 11 may furthermore be used to measure the temperature of the liquid or a piece in contact with the liquid, in order to interrupt or modify the electric current as a function of the measured temperature. In a variant, the temperature sensor 11 also makes it possible to detect the presence or absence of the liquid in the cylinder 2 because the temperature progression of the cylinder varies accordingly. The Heating is thus secure in case of absence of liquid.

The different branches of the circuit 70, 71 do not necessarily all have the same length, the same thickness, the same width and / or the same electrical resistance.

In an advantageous embodiment, the pressure of the liquid ejected from the cylinder is also controlled by means of a reaction loop, in order to use a pressure of the liquid through the beverage powder adapted to the type of drink. longed for. The pressure of the liquid directly influences the quality of the coffee or drink. For this purpose, the device of the invention advantageously comprises a pressure detector 13 downstream of the cylinder, supplying a measurement value used by a control circuit to control the current applied to the piston translation system and thus obtain a pressure of constant liquid during the evacuation and close to the set point depending on the desired drink. The system makes it possible not only to control and possibly modify the extraction pressure of the discharged liquid, but in a variant it also makes it possible to perform a reversal of the flow. The reversibility of the pump makes it possible, for example, to re-suck up part of the extracted coffee or to rinsing the device. In another variant the pressure can be deduced from the knowledge of the consumption current of the engine 1, without using the sensor 13. The thin-film heating element can be replaced by an Egotherm-type resistor. ), or very similar heating systems having heating elements wound and welded around the outer surface of a cylinder. Alternatively, the heating element is replaced or supplemented with a cooling element, for example Peltier type, to lower the temperature of a liquid that enters the preheated pump.

The device described above can be further modified by using two or more pistons advantageously working out of phase to transfer and heat several times quantntrôlées liquid quantities. This makes it possible to supply a hot liquid continuously without any dead point when filling the piston. Moreover, by modifying the number of pistons actually used, it is possible to control the volume of heated and transferred liquid. The number of pistons used can be modified using numerical controls to control the valves that must be opened or closed during each cycle, and possibly the pistons that need to be moved. The different pistons can be driven by the same engine or cylinder, or by individual cylinders. It is also possible to use double-acting pistons, which sucks and pumps the liquid continuously to reduce the pulling time.

We will now describe the process implemented to produce a desired amount of hot liquid. In a first step, at least one electrical switch (for example 72 or 72 + 73) is open in order to circulate an electric current in one of the conductive tracks 70, 71 on the outer surface 20 of the cylinder, so as to preheat this cylinder . The heat produced by the thin resistive layers is immediately transmitted to the corresponding portion of the walls of the cylinder 2. Simultaneously, or shortly before or after, the inlet valve 4 is opened while the expulsion valve 5 is closed, by electromechanically under the control of an electronic control circuit, or mechanically, for example by means of springs.

The piston 3 is then raised under the action of the engine 1, so as to suck the liquid inside the cylinder 2 and through the intake valve 4. The heating of the cylinder is preferably continued at course of aspiration. The stroke of the piston 3 is preferably regulated so as to correspond to the volume of liquid to be produced by means of the open-loop control or closed feedback loop mentioned above. The heating of the liquid can therefore be started at the beginning of the suction, so to arrive quickly at the desired temperature, or only at the end of the aspiration, after a given time, in order to avoid the risk of an excessive temperature if a large energy is transmitted to a reduced volume of liquid.

When the piston 3 has reached the end of travel or the height corresponding to the desired volume of liquid, it is preferably maintained at this position for the time necessary for heating the liquid to the desired temperature. This time can be determined according to the volume of liquid, or preferably interrupted when the temperature sensor 11 indicates that the liquid has reached the desired temperature, for example 94 ° C for the coffee. In one embodiment, the current flowing through the resistors is progressively reduced when the temperature of the liquid approaches the setpoint, in order to arrive precisely at this value quickly and without exceeding it. The electric current injected into the circuit, as well as the number of branches through which a current flows, can be regulated according to the volume of liquid to be heated and / or the target temperature to be reached. The inlet valve 4 is preferably closed as soon as the piston has reached its maximum height, in order to prevent the heated liquid from coming out through the inlet channel or the heat escaping by convection or mixture of liquid. .

The expulsion valve 5 is then opened, and the piston 3 down to expel a first volume of hot liquid. This volume of liquid enters a volume of coffee or powder (not shown), so as to moisten and wet the powder. The advance of the piston is interrupted for a predetermined time T1 when the liquid has sufficiently penetrated into the powder and before a substantial amount of liquid has passed through it. This duration allows the flavors of coffee or powder to dissolve in the liquid. In a preferred embodiment, the piston is slightly raised at the beginning of this period T1, in order to release the pressure of the liquid around the powder and thus allow the flavors to dissolve more easily in the liquid. It is advantageous to use a pressure of approximately 1 bar, or even slightly less than 1 bar, for a period of 1 to 3 seconds, and with a water temperature of approximately 94 ^° C. The use of a piston pump makes it possible to control very precisely the pressure of the liquid and the volume of liquid injected into the powder. In an advantageous embodiment, a part of the liquid wetting the powder is sucked back into the cylinder during this step. The liquid can thus flow in both directions through the valve 5, which also allows to suck up part of the extracted coffee or rinse the parts downstream of the cylinder.

After this time Tl, the piston is again actuated in the second direction, so as to increase again the pressure of the liquid in the powder chamber, to cause the expulsion of the liquid on the other side of the powder, towards the cup. The use of a much higher pressure during this expulsion step makes it possible to release other flavors that do not dissolve easily in hot water but that can in some way be torn off by this pressure.

The heating of the cylinder can be maintained and regulated during the duration T1 and during the expulsion phase that follows, so as to ensure a constant temperature of the liquid throughout the expulsion. In a preferred embodiment, the heating is interrupted, or at least reduced by decreasing the electric current, before the complete expulsion of the liquid out of the cylinder. The thermal inertia of the cylinder is thus exploited and it is avoided to transmit heat to the cylinder which will not have time to be communicated to the liquid. The interruption or rapid reduction of the heating also makes it possible to avoid excessive temperature differences between the last drops of liquid expelled and those leaving the cylinder first, which makes it possible, for example, to avoid the production of unnecessary vapor by evaporation of the last drops of liquid. It is also possible to modify the electrical connections of the heating circuit during the displacement of the piston, and for example to interrupt more quickly the supply of printed tracks which cover the top of the emptied cylinder first.

An electronic circuit 8, for example a microcontroller controlled by a computer program or an FFGA circuit, preferably controls the following sequence of events:

• Opening of the inlet valve 4, and closing of the expulsion valve 5.

• Supply of the motor 1 so as to cause the movement of the piston in a first direction, in order to suck the liquid in the cylinder.

• Closing the inlet valve 4.

Control of different tracks 70, 71, .. of the heating circuit 7, in order to heat the liquid in the cylinder to the set temperature.

• Interruption or reduction of the electric current in the tracks 70, 71, .. as soon as the temperature of the liquid reaches or approaches the set temperature.

• Opening the expulsion valve 5.

• Supply of the motor 1 so as to cause the displacement of the piston in a second direction, in order to expel part of the liquid in the powder reservoir not shown.

• Supply of the motor 1 so as to cause the displacement of the piston in the first direction, in order to suck up a part of the liquid in the powder tank and to release the pressure of the liquid around the powder.

• Waiting for a period of time T1.

• Supply of the engine 1 so as to cause the displacement of the piston in the second direction, in order to expel all the liquid contained in the cylinder, or a volume corresponding to the amount of hot beverage desired.

In the embodiments described above, the liquid is heated in the cylinder. However, it is also possible to suck and transfer a liquid with the described pump without heating it, for example by controlling the heater body so as not to circulate current, or by providing a pump without heating body or by sucking already hot liquid.

The device and the method of the invention can be used for example for a coffee machine, including a coffee machine for car or caravan or mobile home, or all electrically autonomous vehicles such as had, taxi, trains, boats etc. A similar pump can also be used for the dosing of heated liquid, in the food industry for the production of other hot drinks, including tea, broths, hot chocolates, etc.

Claims

claims

A method for delivering a volume of hot beverage, comprising the following steps: a) Opening a liquid inlet valve (4) to allow liquid to enter a heating cylinder (2), b) Displacement longitudinal in a first direction of a piston (3) in said cylinder (2), so as to suck said determined volume of liquid into said heating cylinder (2) through said inlet valve (4), c) closing said intake valve (4), and opening of an expulsion valve (5), d) longitudinal movement in a second direction opposite to said first direction of said piston (3) in said cylinder (2), so as to expel at through said expulsion valve (5) at least a portion of the heated liquid out of said cylinder and wetting a powder, e) Waiting for a predetermined time, f) Moving longitudinally in said first direction of said piston (3) in said cylinder (2 ), in order to reduce the pressure of the in the powder, g) longitudinal displacement in said second direction of said piston (3) in said cylinder (2), so as to expel through said expulsion valve (5) the liquid through said powder and to deliver said volume hot drink.

2. The process of claim 1 wherein heating of the liquid in said cylinder is maintained in step e above.

The method of claim 2, wherein the heating of the liquid in said cylinder is reduced in step e above.

4. The process of one of claims 1 to 3, wherein the heating of the liquid in said cylinder is maintained in the course of step g above.

The method of claim 4, wherein the heating of the liquid in said cylinder is controlled during step g above, so as to ensure a constant liquid temperature throughout the expulsion.

The method of one of claims 1 to 5, wherein the liquid is heated to a first setpoint temperature in step e above, and to a different setpoint temperature in step g. - above.

7. The method of one of claims 1 to 6, wherein the heating is interrupted before starting the expulsion of the liquid and when the liquid has reached a predetermined set temperature.

The process of one of claims 1 to 7, wherein the liquid is already heated in step b above.

9. The method of one of claims 1 to 8, wherein the pressure of the liquid downstream of the cylinder is measured with the aid of a pressure detector (13) and controlled using a control circuit. regulation (8).

10. Liquid pump comprising:

a cylinder (2);

an intake valve (4) for liquid in the cylinder;

an expulsion valve (5) of said liquid out of the cylinder;

a piston (2) sliding in said cylinder so as to suck said liquid into the cylinder and then expel it from the cylinder;

an electric circuit (7) for heating the cylinder with at least one resistor (70, 71) for electrically heating the liquid in the cylinder, characterized by: a temperature probe (11) for measuring the temperature of the liquid in the cylinder, and an electronic circuit (8) arranged to carry out the method of one of claims 1 to 9.