DEVICE FOR PREPARING A COFFEE BEVERAGE

Abstract

In a device for preparing a coffee beverage with a scalding unit that can be supplied with pressurized hot water from a water heater and a beverage outlet connected to the scalding unit via an outlet conduit, through which a freshly scalded coffee beverage can be dispensed into a drinking vessel to be placed below, a recirculation pump is provided which, on the suction side, is connected so as to conduct fluid with the outlet conduit and which, on the discharge side, leads to a drain or collection vessel, for drawing the coffee beverage from the coffee conduit before, during, or after a scalding process and conveying it to the drain or collection vessel.A control is used to control the recirculation pump and is configured to activate the recirculation pump during a preheating process in which hot water is introduced into the outlet pipe or into the scalding unit and the outlet pipe.

Description

DEVICE FOR PREPARING A COFFEE BEVERAGE The present invention relates to a device for preparing a coffee beverage with a scalding unit that can be fed with pressurized hot water from a water heater and a beverage outlet connected to the scalding unit through an outlet conduit, through which a freshly scalded coffee beverage can be dispensed into a drinking vessel to be placed below. Commercially available coffee machines, such as fully automatic coffee machines or espresso machines, feature a brewing chamber into which ground coffee is placed. The ground coffee is compressed, and then hot water is passed through it under pressure. Some of these machines have an integrated cleaning function, which involves circulating hot water or rinse fluid through the brewing chamber. The rinse fluid can be dispensed into a container located below the beverage outlet, which the user can then dispose of manually. However, it is also common to connect the outlet pipe leading to the beverage outlet directly to a drain or collection container via a corresponding diverter valve, thus ensuring that the rinse fluid does not accidentally reach a drinking vessel.A switching valve of this type can also be used to connect the outlet pipe to the drain or collection container after the brewing process is complete, preventing coffee grounds from dripping out. However, a switching valve (3 / 2 directional control valve) located in the outlet pipe has the disadvantage of a relatively high heat capacity and therefore further cools the freshly brewed coffee as it travels from the brewing unit to the beverage outlet. The present invention aims to provide a device for preparing a coffee beverage that prevents the freshly brewed coffee from cooling down on the journey from the brewing unit to the beverage outlet. The objective is achieved through the features of claim 1. Advantageous configurations are indicated in the dependent claims. In a device of the type described at the beginning, a recirculation pump is provided, which on the suction side is connected so as to convey fluid to the outlet conduit and which discharges on the discharge side into a drain or collection container, for drawing the coffee beverage from the coffee conduit before, during, or after a scalding process and conveying it to the drain or collection container. Instead of connecting the outlet conduit to a drain conduit via a valve, in the present invention the liquid is therefore drawn from the outlet conduit by means of negative pressure and conveyed to the drain conduit. Furthermore, the device is designed to be preheated with hot water, using the recirculation pump according to the invention, after a long period of inactivity before preparing a coffee beverage. This can be achieved by briefly running a flow of hot water through the brewing unit and the outlet pipe before filling the brewing unit with ground coffee. Alternatively, the brewing unit may be equipped with its own heater and therefore preheating is not necessary. In this case, only the outlet pipe can be preheated by running a flow of hot water through an additional valve into the outlet pipe.In both cases, according to the invention, the recirculation pump is activated by the associated control during a preheating phase to draw in the hot water used for preheating, so that it is not dispensed through the drinking outlet into a drinking container placed below. Similarly, the recirculation pump can be used in a cleaning process to draw in cleaning fluid. Hot water is supplied from the water heater to the scalding unit via a hot water supply line. This is conveniently achieved using a water pump, which delivers pressurized water from a water supply or storage tank to the scalding unit. The water pump may be located within the hot water supply line running from the water heater to the scalding unit. However, it is more common for the hot water pump to be located on the water heater's supply side, within its cold water supply line. This pump delivers cold water to the water heater, which then pumps hot water to the scalding unit. The water heater may be configured as a standard hot water boiler or as a continuous flow water heater. In a preferred embodiment, the device features a programmable controller for operating the recirculation pump. This controller can perform a variety of functions. Preferably, it can be configured to remove any remaining coffee from the outlet after a brewing process. This prevents subsequent dripping from the beverage outlet. Furthermore, it ensures that no coffee remains in the coffee outlet the next time a product is brewed, so that only freshly brewed coffee is dispensed. Liquid residue can be extracted from the outlet pipe after each individual brewing process. Alternatively, the outlet pipe can be left unemptied until after a specified inactivity period. This allows for multiple coffee drinks to be dispensed consecutively without extraction. The outlet pipe is only emptied after a period of inactivity. The recirculation pump can also be briefly activated before brewing coffee to ensure no liquid residue remains in the outlet pipe. However, with the help of the recirculation pump, selective modification of the flavor of a brewed coffee beverage can also be achieved. To do this, the control system is configured to operate the recirculation pump in such a way that, during the brewing process, portions of the freshly brewed coffee are selectively drawn off (drained) in a time-controlled manner and are therefore not dispensed through the beverage outlet into the user's drinking vessel. This is based on the understanding that different aroma carriers are released from the ground coffee throughout the extraction time. Thus, the first part (for example, from 0 to 10 seconds) of a coffee is more acidic, while the last part has a more bitter flavor. Therefore, the recirculation pump can be used to drain the unwanted portions of the brewed coffee during the brewing process.For example, the initial phase can be drained to obtain less acidity in the final product. i +?ηζ1 n / rznz / B / YiAi A particularly advantageous improvement is achieved when the control system is configured to vary the recirculation pump's flow rate during operation, thus altering the amount of coffee dispensed per unit of time through the outlet during the brewing process. This allows for partial drainage of the beverage during certain periods of the extraction time, by reducing the suction pump's flow rate. For example, 40% of the coffee can be drained for 2 to 5 seconds by activating the pump at a reduced flow rate during this interval. By specifying the activation times and flow rates, different flavor profiles of the finished coffee beverage can be achieved. In an improvement of the invention, a scalding valve may be provided upstream of the scalding unit, in a hot water supply line, which opens at the start of the scalding process and closes once the scalding process is complete. The control system may be configured so that the recirculation pump is activated before, at the time of closure of the scalding valve, or after its closure. Consequently, the outlet line is emptied by suction shortly before the end of a scalding process, at the time of its completion, or is not emptied until after the scalding process has finished and the scalding valve has closed. In a preferred embodiment, a backpressure valve is arranged in the outlet pipe, between the scalding unit and the drinking outlet. This valve allows for selective regulation of either the pressure in the scalding unit or the flow rate through the scalding unit. Preferably, the recirculation pump is connected to the outlet pipe downstream of the backpressure valve. This ensures that, firstly, the scalding pressure from the scalding unit is not applied to the recirculation pump during a scalding process. Secondly, the return pipe can be emptied by suction to the drinking outlet without the resistance of the backpressure valve. In an alternative embodiment, instead of being directly connected to the outlet pipe, the recirculation pump can also be connected upstream of the scalding unit to the hot water supply pipe or to an outlet of the scalding valve that can be connected to the hot water supply pipe. In this case, the coffee beverage can be drawn back through the scalding unit when the recirculation pump is operating. Therefore, the recirculation pump is connected via the scalding unit to the outlet pipe in such a way that it carries fluid. In a preferred configuration, the recirculation pump is configured as a peristaltic pump. This has proven to be particularly resistant to hot and, in some cases, corrosive liquids (such as acidic coffee), as well as to scale buildup that can occur over time. Other advantages and configurations of the present invention are illustrated in the following description of exemplary embodiments with the aid of figures. Example: Figure 1 is a flow diagram of a coffee brewing device with a recirculation pump connected to the outlet duct in a first embodiment; Figure 2 is a second embodiment with an additional backpressure valve arranged in the outlet duct; Figure 3 is an alternative embodiment with a backpressure valve arranged in the suction duct; Figure 4 is an embodiment of a coffee brewing device with a recirculation pump connected via a scalding valve upstream of the scalding unit; Figure 5 is an alternative embodiment with a recirculation pump connected between the scalding group and the scalding valve.Figure 6 shows another example of an alternative embodiment with a recirculation pump connected upstream of the scalding valve, and Figure 7 shows an example of an embodiment with a heater in the scalding unit and a valve for preheating the outlet duct. Figure 1 shows, in a so-called water flow diagram, the structure of a device for preparing coffee beverages, which can be used, for example, in a fully automatic coffee machine or an espresso machine. The preparation device comprises a scalding unit it?n71 n / rznz / B / YiAi 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 via an outlet pipe 5 to the scalding unit 1. A recirculation pump 6 is also connected to the outlet pipe 5, which discharges on the supply side into a drain 7 or a collection vessel. A scalding valve 8, configured as a 3 / 2 directional control valve, is located in a hot water supply pipe between the hot water boiler 2 and the scalding unit 1. This valve alternately connects the hot water pipe from the hot water boiler 2 to the scalding unit 1 or the scalding unit 1 to the drain 7 or a corresponding collection vessel. Viewed in the flow direction, upstream of the water pump 3 is a main water valve 10, through which the brewing device is connected to a potable water inlet pipe 11. On the discharge side, the pump 3 is connected via a flow sensor 12, also often called a flow meter, and a check valve 13 to the inlet pipe of the hot water boiler 2. Hot water from the hot water boiler 2 is supplied to the scalding unit 1 by applying pressure to the hot water boiler 2 via the water pump 3. A control unit 15 with a user interface 16 controls the function of the brewing device and its components. This control can be implemented by a correspondingly programmed microprocessor, which can also be used to implement other control and regulation processes in a fully automatic coffee machine. The scalding unit 1 comprises, as known, a scalding chamber into which freshly ground coffee powder is introduced in portions, and preferably a heater (see Figure 7.20) with which the scalding unit can be preheated and kept warm. A scalding unit that can be used within the scope of the present invention is described, for example, in document EP 2561778 A1, which is referenced in its entirety to avoid unnecessary repetition. The scalding unit is configured to open and introduce a portioned amount of ground coffee, which has just been pre-ground in portions in a fully automatic coffee machine grinder. Furthermore, when the scalding unit is open, after the scalding process, the remaining coffee grounds can be expelled into a pulp container. The scalding unit also features a movable plunger (not shown) that compresses the introduced ground coffee against a scalding sieve located in the scalding chamber. After the plunger is retracted, pressurized scalding water flows through the compressed ground coffee. The freshly brewed coffee beverage flows from the brewing unit 1 through the outlet pipe 5 to the beverage outlet 4 and from there into a drinking container 14 located below. Once the brewing process is complete, the recirculation pump 6 can be activated by control 15. This pump draws the remaining coffee beverage from the outlet pipe 5 and directs it to the drain 7 or, if applicable, to a collection container connected to the pump. This prevents coffee from subsequently dripping from the beverage outlet 4. Therefore, the remaining coffee beverage in the outlet pipe can be completely and safely emptied. This has the following advantages: The initial flow (flow) of the next product occurs without dripping or splashing, as the gas and coffee mixture can be fully extracted. The remaining coffee does not further cool the next product.Furthermore, the flavor of the next product is not affected by the remaining amount of the coffee beverage. It is also possible to selectively alter the flavor of the dispensed beverage using the recirculation pump 6 by draining the coffee during specific extraction times, i.e., by drawing it into the drain 7. For example, the initial phase can be drained to reduce acidity. Furthermore, the pump allows for regulating the amount of coffee dispensed into the drinking vessel during specific extraction times. For instance, 40% of the coffee can be drained for 2 to 5 seconds, with the recirculation pump 6 adjusting its flow rate accordingly. The operation of the coffee-making device depends on the control unit 15. This reads the various sensors, such as the flow meter 12, and controls the valves 8 and 10, as well as the pumps 3 and 6, and the scalding unit 1. Of course, other sensors for pressure, temperature, flow, etc., may be provided, which are not shown here for clarity, and whose measured values ​​are read by the control unit 15. Control unit 15 also controls an automatic cleaning process, in which the rinse water is conveyed through the scalding unit 1 and the outlet pipe 5. In this process, it specifically activates the recirculation pump 6 to draw the rinse water from the outlet pipe 5 and direct it to the drain 7. Control unit 15 also controls a heating process, in which hot water is conveyed through the scalding unit 1 and the outlet pipe 5 for preheating. In this case as well, the recirculation pump 6 is activated to draw the wash water from the outlet pipe to the drain 7. The following embodiments explain variations and different embodiments of the coffee brewing device shown in Figure 1. In this context, only the flow path from the hot water boiler 2 is represented. In the embodiment shown in Figure 2, an adjustable backpressure valve 9 is additionally located in the outlet pipe 5. This valve is preferably a motor-controlled needle valve and creates flow resistance in the outlet pipe, so that the water pressure in the brewing unit 1 is not directed solely onto the coffee cake in the brewing chamber, but also onto the backpressure valve 9, depending on its opening position.With the help of control 15, the backpressure valve 9 can be regulated in such a way as to achieve a certain flow rate or a certain total flow time of a predefined quantity of scalding water or a certain pressure in the scalding unit 1. Upstream of the backpressure valve 9, the recirculation pump 6 is conveniently connected to the outlet pipe 5, so that it can draw freshly scalded coffee beverage from the outlet pipe 5 after the completion of a scalding process or also during a scalding process, regardless of the opening state of the backpressure valve 9. In an alternative embodiment shown in Figure 3, the recirculation pump 6 is connected to the recirculation conduit 5 upstream of the backpressure valve 9, so that the freshly scalded coffee beverage can be drawn directly behind the scalding unit 1. To empty the outlet conduit 5, the backpressure valve 9 can conveniently be fully opened once the scalding process is complete, so that the coffee beverage can be drawn by the recirculation pump 6 without additional resistance and thus reliably and quickly. In the embodiment shown in Figure 4, the recirculation pump 6 is connected to the third connection of the scalding valve 8 (3 / 2 directional control valve) such that, when the scalding valve is closed, the scalding unit 1 can be emptied by the recirculation pump 6 towards the drain 7. In this way, the outlet pipe 5 can be emptied by suction through the scalding unit 1. For this purpose, the scalding plunger of the scalding unit 1 is conveniently retracted and the ground coffee contained in the scalding chamber is expelled into a pulp container (not shown). Alternatively, as shown in Figure 5, the recirculation pump 6 can also be connected in the connecting pipe between the scalding valve 8 and the scalding unit 1. In this case as well, when the scalding valve is closed, the fluid remaining in the scalding unit 1 can be drawn off by the recirculation pump 6 and directed to the drain 7. Finally, Figure 6 shows an embodiment in which the recirculation pump 6 is connected upstream of the scalding valve 8. In this case, once the scalding process is complete, the scalding valve can first be closed and the liquid contained in the feed line drained through the scalding valve 8 to the drain. The scalding valve can then be reopened so that the coffee beverage remaining in the scalding unit 1 and in the outlet line 5 can be drawn in by the recirculation pump 6 and discharged to the drain 7. As already explained, the recirculation pump 6 is preferably configured as a peristaltic pump, so that the pump's moving parts do not come into contact with the hot and potentially corrosive coffee beverage. However, other correspondingly robust types of pumps can also be used. Figure 7 shows an embodiment that essentially corresponds to that shown in Figure 1. Additionally, an electric heater 20 for the scalding unit 1 is shown, which allows the unit to be preheated. Furthermore, there is a switching valve 17 in the outlet pipe, behind the scalding unit 1. In normal operation, this valve connects the outlet of the scalding unit 1 to the outlet pipe 5. To preheat the outlet pipe after a long period of inactivity, control 5 can switch the valve 17 to allow a flow of hot water through the outlet pipe 5. For this purpose, the inlet 18 of the switching valve 17 is connected to a water heater, such as the hot water boiler 2 in Figure 1.During this heating process, the recirculation pump 6 is activated by control 15 to draw in the hot water used for preheating 10, preventing it from being dispensed through the beverage outlet 4 into a drinking vessel 14 below. Preheating the outlet pipe 5 and the scalding unit 1 prevents freshly scalded coffee from cooling down in the coffee machine before reaching the drinking vessel 14. The operation of the recirculation pump 6 during preheating also prevents the outlet pipe 5 from being full of water at the start of a coffee extraction, which would otherwise be dispensed into the drinking vessel during extraction and dilute the coffee.

Claims

1. A device for preparing a coffee beverage comprising a scalding unit (1) to which hot water can be supplied under pressure from a water heater (2) and a beverage outlet (4) connected to the scalding unit (1) via an outlet conduit (5), through which a freshly scalded coffee beverage can be dispensed into a drinking vessel (14) to be placed below, characterized by a recirculation pump (6) which on the suction side is connected so as to conduct fluid with the outlet conduit (5) and which opens on the discharge side into a drain (7) or a collection vessel, for drawing the coffee beverage from the outlet conduit (5) before, during, or after a scalding process and conveying it to the drain (7) or the collection vessel, and by a control (15) for controlling the recirculation pump (6),with the control (15) configured to introduce hot water into the outlet pipe (5) or into the scalding unit (1) and the outlet pipe (5) during a preheating process and to activate the recirculation pump (6) during the preheating process.

2. Device according to claim 2, wherein the control (15) is configured to control the recirculation pump (6) in such a way that, after a scalding process, the remains of the coffee beverage that may have remained in the outlet duct (5) are aspirated.

3. Device according to claim 2 or 3, wherein the control (15) is configured to control the recirculation pump (6) in such a way that during the scalding process of a coffee beverage, parts of the freshly scalded coffee beverage are selectively drained in a time-controlled manner.

4. Device according to claim 4, wherein the control (15) is configured to vary, by controlling the recirculation pump (6), the transport speed thereof during operation to vary the amount of coffee beverage dispensed per unit of time through the outlet (4) during the scalding process.

5. Device according to any one of claims 2 to 5, having a scalding valve (8) arranged upstream of the scalding unit (1) in a hot water supply conduit, which opens when the scalding process begins and closes once the scalding process is completed, the control (15) being configured to activate the recirculation pump (6) before the closing of the scalding valve (8), at the time of closing or after closing.

6. Device according to one of the preceding claims with a backpressure valve (9) arranged in the outlet conduit (5) between the scalding unit (1) and the drinking outlet (4), diverting the recirculation pump suction conduit (6) preferably downstream of the backpressure valve (9) from the outlet conduit (5).

7. Device according to any of the preceding claims, wherein the suction conduit of the recirculation pump (6) is connected upstream of the scalding unit (1) to the hot water supply conduit or to an outlet of the scalding valve (8) that can be connected to the hot water supply conduit in such a way that the coffee beverage is drawn back by the scalding unit (1) when the recirculation pump (6) is in operation.

8. Device according to one of the preceding claims, wherein the recirculation pump (6) is a peristaltic pump.

9. Device according to any of the preceding claims, wherein the control (15) is configured to briefly activate a flow of hot water through the scalding unit (1) and the outlet conduit (5) to carry out the preheating process before filling the scalding unit (1) with ground coffee.

10. Device according to any of the preceding claims, wherein the scalding unit (1) is provided with a heater (20) and the control (15) is configured to activate by means of a valve (17) a flow of hot water through the outlet conduit (5) to carry out the preheating process.

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