DEVICE FOR PREPARING A COFFEE DRINK

Description

[0001] The present invention relates to a device for preparing a coffee beverage, comprising a brewing unit to which hot water from a hot water heater can be supplied under pressure, and a beverage outlet connected to the brewing unit via an outlet line, via which freshly brewed coffee beverage can be dispensed into a drinking vessel to be placed underneath.

[0002] A coffee preparation device according to the preamble of claim 1 is known from WO 2015 / 084005 A1. An additional pump is used there to rinse out coffee residues following a preparation cycle.

[0003] Coffee machines available on the market, such as fully automatic coffee machines or espresso machines, have a brewing chamber into which ground coffee is poured, which is then compressed if necessary, and then hot water is passed through under pressure. Some such coffee machines have an integrated cleaning function, during which hot water or rinsing liquid is passed through the brewing chamber. The rinsing liquid can be dispensed into a container placed below the beverage outlet and manually poured away by the user. However, it is also known to connect the outlet line leading to the beverage outlet directly to a drain or collecting container via a corresponding changeover valve, thus ensuring that rinsing liquid does not accidentally enter a drinking vessel.Such a diverter valve can be used to connect the outlet line to the drain or collection container even after the brewing process has finished, preventing residual coffee from dripping. However, a diverter valve (3 / 2-way valve) located in the outlet line has the disadvantage of a relatively high heat capacity, thus further cooling the freshly brewed coffee on its way from the brewing unit to the beverage outlet.

[0004] The present invention has for its object to provide a device for preparing a coffee beverage which prevents the freshly brewed coffee from cooling down on the way from the brewing unit to the beverage outlet.

[0005] The problem is solved by the features of claim 1. Advantageous embodiments can be found in the dependent claims.

[0006] In a device of the type mentioned above, a suction pump is provided, which is fluidly connected to the outlet line on the intake side and opens into a drain or collection container on the pressure side. It is used to suction coffee beverage from the coffee line before, during, or after a brewing process and direct it into the drain or collection container. Instead of connecting the outlet line to a drainage line via a valve, the present invention thus suctions liquid from the outlet line using negative pressure and directs it into the drainage line.

[0007] Furthermore, it is provided that after a lengthy downtime, the device is preheated with hot water using the suction pump according to the invention before preparing a coffee beverage. This can be done either by briefly passing a stream of hot water through the brewing unit and outlet line before filling the brewing unit with coffee powder. Alternatively, the brewing unit can be provided with its own heater and therefore does not need to be preheated. In this case, only the outlet line can be preheated by directing a stream of hot water into the outlet line via an additional valve. In both cases, according to the invention, the suction pump is activated via the associated control system during such a preheating phase in order to suck out the hot water used for preheating so that it is not dispensed via the beverage outlet into a drinking vessel placed underneath.In the same way, the suction pump can be used during a cleaning process to suck out cleaning fluid.

[0008] The hot water supply from the hot water heater to the brewing unit via a hot water supply line is conveniently carried out by a water pump, which pumps water under pressure from a water connection or from a water tank toward the brewing unit. The water pump can be located in the hot water supply line leading from the hot water heater to the brewing unit. However, the hot water pump is conveniently located on the inlet side of the hot water heater in its cold water supply line, thus pumping cold water to the hot water heater, which in turn supplies hot water to the brewing unit under the pressure of the pump. The hot water heater can be designed in a conventional manner as a hot water boiler or as an instantaneous water heater.

[0009] In a preferred embodiment, the device has a programmable controller for controlling the suction pump. A variety of functions can be implemented with such a controller. Preferably, the suction pump is controlled by the controller in such a way that, following a brewing process, any coffee beverage residue remaining in the outlet line is sucked out. This prevents coffee from dripping from the beverage outlet. Furthermore, it ensures that no coffee beverage that has cooled down in the meantime remains in the coffee line during the next product preparation, so that only freshly brewed coffee beverage is dispensed at the beverage outlet.

[0010] The liquid residue can be removed from the outlet line after each individual brewing cycle. Alternatively, it is also possible to empty the outlet line only after a certain period of inactivity. This allows several coffee beverages to be dispensed in quick succession without the need for siphoning. The outlet line is only emptied after a period of inactivity. It is also possible to briefly activate the suction pump before starting a coffee brewing cycle to ensure that no liquid residue remains in the outlet line.

[0011] In addition, the suction pump can also be used to achieve a targeted change in the flavor of a prepared coffee beverage. For this purpose, the control system is designed to activate the suction pump in such a way that, during the brewing process, portions of the freshly brewed coffee beverage are selectively suctioned ("drained away") at a specific time, preventing them from being dispensed into the user's drinking vessel via the beverage outlet. This is based on the knowledge that different aroma carriers are released from the coffee powder over the extraction time. For example, the first part of a coffee (e.g., 0 to 10 seconds) has a more acidic flavor, while the last part tastes more bitter. The suction pump can thus drain away unwanted extraction periods during a preparation process. For example, the initial phase can be drained away to reduce the acidity in the final product.

[0012] A particularly advantageous development results if the control system is designed such that, by controlling the suction pump, its delivery speed is varied during operation in order to vary the amount of coffee beverage dispensed per unit of time via the outlet during the brewing process. This makes it possible to only partially drain the beverage portions during certain extraction periods, rather than completely, by reducing the delivery speed of the suction pump. For example, 40% of the coffee beverage can be drained during a time period of 2 to 5 seconds by activating the pump at a reduced delivery speed during this time interval. By specifying the activation times and the delivery rate, different flavor characteristics of the finished coffee beverage can be achieved.

[0013] In a further development of the invention, a brewing valve can be provided upstream of the brewing unit in a hot water supply line. This valve is opened to start the brewing process and closed after the brewing process is complete. The control system can be configured to activate the backflow pump before, together with, or after the brewing valve is closed. Accordingly, the outlet line is emptied shortly before the brewing process is completed, together with its completion, or only after the brewing process has ended and the brewing valve has been closed.

[0014] In a preferred embodiment, a backpressure valve is arranged in the outlet line between the brewing unit and the beverage outlet. This valve can be used to specifically regulate the pressure in the brewing unit or a flow rate through the brewing unit. Preferably, the backpressure pump branches off from the outlet line downstream of the backpressure valve. Thus, the backpressure pump is not subjected to the brewing pressure of the brewing unit during a brewing process. On the other hand, the backpressure line can be drained to the beverage outlet without the resistance of the backpressure valve.

[0015] In an alternative embodiment, the backflow pump can be connected upstream of the brewing unit to the hot water supply line or to an outlet of the brewing valve that can be connected to the hot water supply line, instead of directly to the outlet line. In this case, the coffee beverage can be sucked back through the brewing unit when the backflow pump is operating. Thus, the backflow pump is fluidly connected to the outlet line via the brewing unit.

[0016] In a preferred embodiment, the recirculation pump is designed as a peristaltic pump. This proves particularly robust against hot and potentially corrosive liquids (acidic coffee), as well as against deposits that can form over time.

[0017] Further advantages and embodiments of the present invention will become apparent from the following description of exemplary embodiments with reference to the figures. It shows: Figure 1 shows a flow diagram of a coffee preparation device with a back-suction pump connected to the outlet line in a first embodiment, Figure 2 shows a second embodiment with an additional back-pressure valve arranged in the outlet line, Figure 3 shows an alternative embodiment with a back-pressure valve arranged in the intake line, Figure 4 shows an embodiment of a coffee preparation device with a back-suction pump connected via a brewing valve upstream of the brewing unit, Figure 5 shows an alternative embodiment with a back-suction pump connected between the brewing group and the brewing valve, Figure 6 shows a further alternative embodiment with a back-suction pump connected upstream of the brewing valve and Figure 7 shows an embodiment with a heater in the brewing unit and a valve for preheating the outlet line.

[0018] In Figure 1In a so-called water flow diagram, the structure of a device for preparing coffee beverages is shown, which can be used, for example, in a fully automatic coffee machine or an espresso machine. The preparation device comprises a brewing unit 1, a hot water boiler 2, a water pump 3 on the inlet side, and a beverage outlet 4 for dispensing freshly brewed coffee beverages, which is connected to the brewing unit 1 via an outlet line 5. Also connected to the outlet line 5 is a return pump 6, which opens into an outlet 7 or a collecting container on the pressure side. In a hot water supply line between the hot water boiler 2 and the brewing unit 1 there is a brewing valve 8, which is designed as a 3 / 2-way valve. This alternately connects the hot water line coming from the hot water boiler 2 to the brewing unit 1 or the brewing unit 1 to the outlet 7 or a corresponding collecting container.

[0019] Upstream of the water pump 3 in the flow direction is a main water valve 10, via which the preparation device is connected to a drinking water supply line 11. On the pressure side, the pump 3 is connected to the inlet of the hot water boiler 2 via a flow sensor 12, often also referred to as a flowmeter, and a check valve 13. By pressurizing the hot water boiler 2 using the water pump 3, hot water from the hot water boiler 2 is supplied to the brewing unit 1. A controller 15 with a user interface 16 controls the function of the preparation device and its components. The control can be implemented by an appropriately programmed microprocessor, which can also be used to implement other control and regulation processes in a fully automatic coffee machine.

[0020] The brewing unit 1 comprises, in a manner known per se, a brewing chamber into which portioned, freshly ground coffee powder is poured, and preferably a heater (see Fig. 7 , 20), with which the brewing unit can be preheated and kept warm. A brewing unit that can be used within the scope of the present invention is described, for example, in EP 2561778 A1, which is hereby incorporated by reference in its entirety to avoid unnecessary repetition.

[0021] The brewing unit is designed so that it can be opened to add a portion of coffee powder, which has previously been freshly ground in a grinder of the fully automatic coffee machine. Furthermore, with the brewing unit open, the remaining coffee grounds can be ejected into a grounds container after the brewing process. The brewing unit also features a movable piston (not shown) that compresses the added coffee powder against a brewing sieve located in the brewing chamber. After the piston retracts, the compressed coffee powder can be flowed through by the pressurized brewing water.

[0022] The freshly brewed coffee beverage flows from the brewing unit 1 via the outlet line 5 to the beverage outlet 4 and from there into a drinking vessel 14 placed underneath. After the brewing process is complete, the control unit 15 can activate the suction pump 6, which sucks away any coffee beverage remaining in the outlet line 5 and directs it into the drain 7 or a collecting container connected to the pump, if applicable. This prevents coffee from dripping from the beverage outlet 4. The residual amount of coffee beverage still in the outlet line can thus be completely and reliably emptied. This has the following advantages: The start-up (dispensing behavior) of the next product occurs without dripping or splashing, as the gas / coffee mixture can be completely drawn off. The residual amount of coffee does not additionally cool the next product.In addition, the remaining amount of coffee drink does not impair the taste of the next product.

[0023] Furthermore, the backflow pump 6 makes it possible to achieve targeted flavor changes in the dispensed beverage by draining certain extraction time periods, i.e., by sucking the coffee into the outlet 7. For example, the initial phase can be drained away to obtain less acid. Furthermore, the pump makes it possible to regulate the amount of coffee dispensed into the drinking vessel during certain extraction time periods. For example, 40% of the coffee can be drained away during a time period of 2 to 5 seconds by adjusting the delivery speed of the backflow pump 6 accordingly.

[0024] The function of the coffee preparation device is determined by the control unit 15. This reads the various sensors, such as the flow meter 12, and controls the valves 8 and 10, the pumps 3 and 6, and the brewing unit 1. Of course, additional sensors for pressure, temperature, flow, etc., not shown here for the sake of clarity, can be provided, the measured values of which are read by the control unit 15.

[0025] The control unit 15 also controls an automatic cleaning process in which rinsing liquid is pumped through the brewing unit 1 and the outlet line 5, and in particular activates the backflow pump 6 to suck the rinsing liquid out of the outlet line 5 and into the drain 7. Likewise, the control unit 15 controls a warm-up process in which hot water is pumped through the brewing unit 1 and the outlet line 5 to preheat them. In this case, the backflow pump 6 is also activated to suck the rinsing water from the outlet line into the drain 7.

[0026] In the following examples, variants and modifications of the Figure 1 Only the fluid path from the hot water boiler 2 is shown. In the Figure 2In the embodiment shown, there is also an adjustable back pressure valve 9 in the outlet line 5. This is preferably implemented as a needle valve controlled by a motor and causes a flow resistance in the outlet line so that the water pressure applied to the brewing unit 1 does not drop exclusively over the coffee cake held in the brewing chamber, but rather drops at the back pressure valve 9 depending on the opening state of the back pressure valve 9. With the help of the controller 15, the back pressure valve 9 can be regulated so that a specific flow rate or a specific total flow time of a predetermined amount of brewing water or a specific pressure in the brewing unit 1 is achieved.The back-suction pump 6 is expediently connected to the outlet line 5 downstream of the back-pressure valve 9, so that it can suck freshly brewed coffee beverage from the outlet line 5 after completion of a brewing process or even during a brewing process, regardless of the opening state of the back-pressure valve 9.

[0027] In an alternative, in Figure 3 In the embodiment shown, the back-suction pump 6 is connected to the back-suction line 5 upstream of the back-pressure valve 9, so that freshly brewed coffee beverage can be sucked away directly behind the brewing unit 1. To empty the outlet line 5, the back-pressure valve 9 can expediently be fully opened after the brewing process has ended, so that the coffee beverage can be sucked away by the back-suction pump 6 without additional resistance and thus reliably and quickly.

[0028] At the Figure 4In the embodiment shown, the backflow pump 6 is connected to the third connection of the brewing valve 8 (3 / 2-way valve) such that, when the brewing valve is closed, the brewing unit 1 can be emptied via the backflow pump 6 in the direction of the outlet 7. The outlet line 5 can be sucked dry through the brewing unit 1. For this purpose, the brewing piston of the brewing unit 1 is expediently retracted, and the coffee powder held in the brewing chamber is ejected into a grounds container (not shown).

[0029] Alternatively, as in Figure 5 As shown, the backflow pump 6 can also be connected in the connecting line between the brewing valve 8 and the brewing unit 1. In this case too, with the brewing valve closed, the fluid remaining in the brewing unit 1 can be sucked out via the backflow pump 6 and directed into the drain 7.

[0030] Finally, in Figure 6An embodiment is shown in which the backflow pump 6 is connected upstream of the brewing valve 8. In this case, after completion of a brewing process, the brewing valve can first be closed and fluid contained in the supply line can be drained into the drain via the brewing valve 8. The brewing valve can then be opened again so that any coffee beverage remaining in the brewing unit 1 and the outlet line 5 can be sucked back by the backflow pump 6 and dispensed into the drain 7.

[0031] As already explained, the recirculation pump 6 is preferably designed as a peristaltic pump, so that the moving parts of the pump do not come into contact with the hot and potentially corrosive coffee beverage. Alternatively, other, appropriately robust pump types can also be used.

[0032] In Figure 7 An embodiment is shown which essentially corresponds to the one in Figure 1shown. In addition, an electric heater 20 of the brewing unit 1 is shown, with which it can be preheated. Furthermore, a switching valve 17 is located in the outlet line behind the brewing unit 1. In normal operation, this connects the outlet of the brewing unit 1 with the outlet line 5. To preheat the outlet line after a longer standstill period, the valve 17 can be switched by the control 15 in order to direct a hot water flow through the outlet line 5. The inlet 18 of the switching valve 17 is connected to a hot water heater, for example the hot water boiler 2 from Figure 1connected. During this warm-up process, the back-suction pump 6 is activated via the controller 15 to suck out the hot water used for preheating so that it is not dispensed via the beverage outlet 4 into a drinking vessel 14 placed underneath. Preheating the outlet line 5 and the brewing unit 1 prevents a freshly brewed coffee beverage from cooling down in the coffee machine before it reaches the drinking vessel 14. Operating the back-suction pump 6 during preheating prevents the outlet line 5 from being filled with water at the start of a coffee dispensing process, which would then be dispensed into the drinking vessel when the coffee is dispensed and dilute the coffee beverage.

Claims

1. A device for preparing a coffee beverage, the device comprising a brewing unit (1) to which hot water from a hot water heater (2) is suppliable under pressure, and a beverage outlet (4) which is connected to the brewing unit (1) via an outlet line (5) and via which freshly brewed coffee beverage is dispensable into a drinking vessel (14) to be placed underneath, and comprising a return pump (6) which is connected on an intake side in a fluid-conducting manner to the outlet line (5) and which opens on a delivery side into a drain (7) or a collecting container in order to suction coffee beverage out of the outlet line (5) before, during or after a brewing operation and to conduct coffee beverage into the drain (7) or collecting container, and a controller (15) for activating the return pump (6), characterized in that the controller (15) is configured to introduce hot water into the outlet line (5) or into the brewing unit (1) and outlet line (5) during a pre-heating operation and to activate the return pump (6) during the pre-heating operation.

2. The device according to claim 1, wherein the controller (15) is configured to activate the return pump (6) such that residues of the coffee beverage remaining in the outlet line (5) following a brewing operation are suctioned away.

3. The device according to claim 1 or 2, wherein the controller (15) is configured to activate the return pump (6) such that, during the brewing operation of a coffee beverage, parts of the freshly brewed coffee beverage are drained away in a time-controlled and targeted manner.

4. The device according to claim 3, wherein the controller (15) is configured, by activating the return pump (6), to vary the pumping speed thereof during operation in order to vary the quantity of the coffee beverage dispensed per unit of time via the outlet (4) during the brewing operation.

5. The device according to any one of claims 1 to 4, comprising a brewing valve (8) which is arranged upstream of the brewing unit (1) in a hot water supply line and which is opened for starting the brewing operation and closed after the brewing operation has been terminated, wherein the controller (15) is configured to activate the return pump (6) before, together with or after the closure of the brewing valve (8).

6. The device according to any one of the preceding claims, comprising a back-pressure valve (9) arranged between the brewing unit (1) and the beverage outlet (4) in the outlet line (5), wherein the suction line of the return pump (6) preferably branches off from the outlet line (5) downstream of the back-pressure valve (9).

7. The device according to any one of the preceding claims, wherein the suction line of the return pump (6) is connected upstream of the brewing unit (1) to the hot water supply line such that coffee beverage is suctioned back through the brewing unit (1) during operation of the return pump (6).

8. The device according to claim 5 or 6, if claim 6 is dependent on claim 5, wherein the suction line of the return pump (6) is connected to an outlet of the brewing valve (8) which is connectable to the hot water supply line such that coffee beverage is suctioned back through the brewing unit (1) during operation of the return pump (6).

9. The device according to any one of the preceding claims, wherein the return pump (6) is a peristaltic pump.

10. The device according to any one of the preceding claims, wherein for carrying out the pre-heating operation, the controller (15) is configured to briefly activate a hot water flow through the brewing unit (1) and the outlet line (5) before the brewing unit (1) is filled with ground coffee.

11. The device according to any one of the preceding claims, wherein the brewing unit (1) is provided with a heater (20) and the controller (15) is configured, for carrying out the pre-heating operation, to activate a hot water flow through the outlet line (5) via a valve (17).