Coffee machine and method of preparing coffee beverage

Abstract

The invention relates to a coffee machine (1) comprising a machine unit (2) comprising: a brewing piston (4) movably mounted between a starting position (AK) and a brewing position (BK); a piston drive (62), which can be controlled by the control unit (20), for moving the brewing piston (4) from the starting position (AK) into the brewing position (BK); a water preparation unit (60) having a water tank (61), a water pump (62) and a heating unit (63) for generating and outputting pressurized hot brewing water into the brewing chamber (3); and a control unit (20) for controlling the coffee machine (1). The coffee machine comprises a blocking unit (11) having at least one blocking element (13) for blocking the brewing piston (4) in the brewing position (BK).

Description

Technical Field

[0001] The invention belongs to the field of coffee machines according to the preamble of independent claim 1 and relates to a coffee machine for making, in particular brewing, a coffee beverage. The invention also relates to a method for making, in particular brewing, a coffee beverage. Background Art

[0002] A number of different coffee machine systems are known for making or brewing coffee beverages. In addition to the known capsule machines, with which coffee powder is supplied to the coffee machine in a pre-portioned manner in capsule form, there are also systems with which coffee powder is filled in a portioned manner into a coffee receiving space for each brewing program. With regard to these systems, a distinction is made between coffee machines that operate in a semi-automatic manner, so-called semi-automatic machines, and coffee machines that operate in a fully automatic manner, so-called bean-to-cup machines.

[0003] In particular, so-called portafilter machines are known among the semi-automatic machines. These machines are characterized by a manually removable portafilter forming a coffee receiving space which is closed to the bottom by a brewing filter. Filling the portafilter with ground coffee and removing the coffee grounds from the portafilter after the brewing process are performed outside the coffee machine. To this end, the portafilter is removed from the machine manually.

[0004] Fully automatic machines differ from semi-automatic machines in that providing ground coffee or filling the coffee receiving space with ground coffee before the brewing process is a fully automatic integrated process within the coffee machine. Furthermore, after the brewing process has ended, the coffee grounds are discharged in a fully automatic manner into an integrated catch container in the coffee machine. Fully automatic machines therefore do not have a removable portafilter.

[0005] Usually, the provision of ground coffee with fully automatic machines is effected via an integrated grinder, by means of which coffee beans from a storage container of the coffee machine are freshly ground for each brewing program.

[0006] In particular, coffee powder in this specification is to be understood as coffee that has been ground, thus ground coffee.Coffee grounds in this specification are to be understood as the compacted residue after the brewing process, also referred to as coffee grounds. Summary of the invention

[0007] The invention relates in particular to fully automatically operated coffee machines, and very particularly to semi-automatically operated coffee machines, such as portable filter machines. With these coffee machines, the coffee powder also needs to be compacted in the coffee receiving space before the brewing process. This process is also called "pressing".

[0008] The compaction of the coffee powder in the coffee receiving space is decisive for the subsequent brewing process, for example for the preparation of espresso with crema, and influences the preparation type of the brewed coffee.

[0009] It is known to achieve compaction of coffee powder, the so-called "tamping", via a movable brewing piston which is advanced or moved downwards into the coffee receiving space via a manual lever or in a fully automatic manner via a piston drive.

[0010] However, each automated step (e.g., for example, the automatic drive of the brewing piston) requires additional components and assemblies, such as a drive element. As a result, the structure of the coffee machine becomes increasingly complex. This leads to a high maintenance workload on the one hand and a high tendency to malfunctions on the other hand. In addition, the additional components, in particular the drive element, make the coffee machine more expensive.

[0011] The object of the present invention is to provide a coffee machine which has a high degree of automation but has as few drive devices as possible for driving the various components via a control device.

[0012] Another object is to provide a coffee machine which allows a defined compaction of the coffee powder, even given a different filling of the portafilter with coffee powder, this compaction being controlled via the control device.

[0013] Another object is to provide a coffee machine with which a movably guided brewing piston is secured against being moved out of the coffee receiving space due to the brewing pressure in the brewing chamber during a brewing procedure. If possible, the securing means should not require any additional drive member.

[0014] At least one of the objects is achieved by the features of the independent claim. The dependent claims, the description and the drawings contain in particular embodiments and further developments of the invention.

[0015] The coffee machine according to the invention comprises a machine unit having

[0016] - a control device for controlling the coffee machine,

[0017] - a brewing piston, which is movably mounted between a home position and a brewing position,

[0018] a piston drive which can be controlled via the control device for moving the brewing piston from the initial position into the brewing position, and

[0019] A water preparation device with a water tank, a water pump and a heating unit for producing hot brewing water under pressure and delivering it to the brewing chamber.

[0020] In particular, the brewing piston is mounted so as to be displaceable along its piston axis, ie axially.

[0021] The present invention is characterized in that the coffee machine comprises a locking device with at least one locking body for locking the brewing piston in the brewing position. In particular, the locking is used to prevent the brewing piston from axially moving out of the brewing position in the direction of the initial position.

[0022] The brewing piston is in particular part of a brewing unit which is formed in the machine unit and comprises a piston tamper. The piston tamper is arranged at the brewing side. In particular, the piston tamper is connected to a piston rod which is in particular guided in a piston rod housing. The piston rod housing is in particular part of a brewing unit in the machine unit.

[0023] In particular, the brewing unit together with the coffee receiving space and the brewing filter, respectively together with the portafilter device, forms a brewing group.

[0024] The brewing piston serves in particular to compact (tamp) coffee grounds which have previously been filled into the coffee receiving space before a brewing process, and to close the coffee receiving space and to form a closed brewing chamber for a subsequent brewing process.

[0025] The coffee receiving space, respectively the coffee receiver forming the coffee receiving space, is particularly arranged in a stationary or immovable manner in the machine unit, particularly during a brewing program. Thus, in the case where the coffee machine is a portable filter machine, this applies accordingly to the portable filter device.

[0026] A brewing water supply for introducing brewing water into the brewing chamber can be guided through the piston tamper.

[0027] The piston drive may comprise an electric motor. The brewing piston may thus be driven by the electric motor via a drive shaft.

[0028] The piston drive may also include a hydraulic drive, by which a hydraulic pressure is established in a pressure chamber in the brewing unit via a hydraulic fluid such as water, which can push or advance or move the brewing piston into the brewing position. The hydraulic pressure can be generated via a pump. The hydraulic pressure can be between 2 and 3 bar, for example.

[0029] According to a further development of the invention, the water pump of the water preparation device is part of the piston drive or forms the piston drive.

[0030] By means of a water pump, a (piston) water pressure acting on the brewing piston is built up, and the brewing piston can be moved from a starting position into a brewing position.

[0031] In this case, the water pump of the water preparation device has a dual function: on the one hand, brewing water is pumped into the brewing chamber by the water pump, and on the other hand, (piston) water for advancing the brewing piston into the pressure chamber in the brewing unit is pumped by the same water pump. Piston water is to be understood as water pumped into the piston water duct by the water pump in order to build up a piston water pressure for moving the brewing piston.

[0032] In particular, the locking device can then be actuated via the piston drive.Thus, the locking device can be actuated by a hydraulic drive, in particular by a water pump of the water preparation device.

[0033] The at least one locking body of the locking device can be displaced into the locking position by building up water pressure, in particular piston water pressure, which acts on the locking device.

[0034] The at least one locking body of the locking device can be displaced into the locking position in an indirect manner, in particular by piston water pressure.

[0035] In particular, the locking device is a locking mechanism.

[0036] In particular, the locking device comprises an actuating element which is movable parallel to the piston axis of the brewing piston.The at least one locking body can be moved into the locking position towards the brewing piston by or via the actuating element.

[0037] In particular, the actuating element can be moved parallel to the piston axis of the brewing piston by hydraulic pressure, in particular fluid pressure or piston fluid pressure, such as water pressure or piston water pressure.

[0038] In particular, the coffee machine is then designed such that for starting a brewing program the piston driver in a first step moves the brewing piston into the brewing position and in a second step after reaching the brewing position actuates the locking device in a locking process of the brewing piston.

[0039] A coffee machine designed as a portable filter machine is particularly designed so that, in order to start a brewing program, the piston drive moves the brewing piston into a brewing position in a first step while compacting the coffee powder by applying a compaction force, and in a second step, when the maximum compaction force is reached and the brewing position is assumed, a locking device is actuated during the locking process of the brewing piston.

[0040] According to a further development of the invention, the piston rod housing is mounted movably along the piston axis. This interacts with an actuating element of the locking device.

[0041] In particular, the piston rod housing and the brewing piston are designed and interact with each other in such a way that the piston drive advances the brewing piston in an axial direction towards the brewing chamber into the brewing position in a first step and subsequently displaces the piston rod housing in an opposite axial direction during actuation of the locking device in a second step.

[0042] The axially movably mounted piston rod housing together with the axially movably mounted brewing piston in particular forms a pressure chamber.

[0043] The piston rod housing and the brewing piston are then designed and interact with one another in particular in such a way that the hydraulic pressure, in particular the (piston) water pressure, generated in the pressure chamber pushes or moves the brewing piston in the axial direction, in particular downwards towards the brewing chamber into the brewing position, and subsequently moves the piston rod housing in the opposite axial direction, in particular upwards during the actuation of the locking device. The movement or displacement of the brewing piston and the piston rod housing is in each case particularly effected counter to the restoring force of the restoring means, which exerts a restoring force on the brewing piston or the piston rod housing.

[0044] In particular, the piston rod housing does not move until the brewing piston has reached the brewing position and the hydraulic pressure in the pressure chamber increases further. This means that the hydraulic pressure for moving the piston rod housing is greater than the hydraulic pressure for moving the brewing piston into the brewing position.

[0045] In particular, the pressure chamber is arranged in an upper section of the brewing unit and very particularly above the brewing piston.

[0046] The brewing piston delimits in particular a lower section of the pressure chamber in such a way that the piston pressure in the pressure chamber is able to push or move the brewing piston axially downwards in the direction of the coffee receiving space.

[0047] In particular, the piston rod housing delimits an upper section of the pressure chamber in such a way that the piston pressure in the pressure chamber can push or move the piston rod housing axially upwards in the opposite direction away from the coffee receiving space.

[0048] The piston rod housing is displaceably mounted, in particular along a longitudinal guide, respectively a vertical guide. The longitudinal guide can be realized, for example, via at least one connecting screw having a particularly threadless guide section. The at least one return spring is particularly arranged on the connecting screw.

[0049] In particular, the piston rod housing is coupled to the actuating element, respectively connected to the actuating element in such a way that the actuating element can be displaced together with the piston rod housing in the axial direction, in particular upwards, to assume the actuating position.The actuating element may also essentially be part of the piston rod housing.

[0050] The locking body is displaced into the locking position by the axial movement of the actuating element and locks the brewing piston. In order to assume the locking position, the locking body is particularly moved transversely to the piston axis or radially toward the brewing piston and is particularly engaged in a groove on the brewing piston.

[0051] According to a further development of the invention, the locking of the brewing piston can be created in different axial positions of the brewing piston and thus in different axial brewing positions of the brewing piston. This is achieved, for example, by at least two or more consecutive grooves arranged in the axial direction on the brewing piston.

[0052] The movement of the piston rod housing is relatively small, in particular compared to the movement of the brewing piston, since this movement is only used to actuate the locking body.

[0053] In particular, the piston rod of the brewing piston is guided through a piston rod guide tube. In particular, the piston rod is guided through the piston rod guide tube from the piston rod housing into the piston tamper guide housing, in which the piston tamper is arranged. The piston rod guide tube thus in particular connects the piston rod housing to the piston tamper guide housing.

[0054] The piston rod housing and the piston rod guide tube are arranged in particular in a stationary, ie non-movable, manner in the machine unit.

[0055] The piston rod guide tube can include at least one radial opening, in particular several radial openings, which are very particularly evenly arranged around the circumference of the piston rod guide tube. The at least one locking body is in particular a ball, which is introduced into the radial opening of the piston rod guide tube and engages in a groove on the piston rod in the locked position, the groove being designed as a deepening. The deepening on the piston rod can be an annular circumferential deepening. In particular, the actuating element is an annular body surrounding the piston rod guide tube.

[0056] The brewing piston can interact with a reset device, in particular a reset spring, by which the brewing piston can be moved back or reset from the brewing position to the initial position after the hydraulic pressure, in particular the (piston) water pressure in the pressure chamber, has dropped. In particular, the reset device is arranged in the piston rod housing.

[0057] In particular, the return spring can be a compression spring.The piston rod of the brewing piston can be axially guided through the compression spring.

[0058] In particular, the compression spring is designed and arranged in the brewing unit in such a way that it is compressed by an advancement or displacement of the brewing piston in the direction of the brewing position and by extension moves the brewing piston back into its initial position.

[0059] According to a further development of the invention, the piston rod housing interacts with a return means, in particular with at least one return spring, by means of which the piston rod housing can be moved from the actuated position back into its initial position after a reduction in the (piston) water pressure.

[0060] In particular, the at least one return spring can be a compression spring. In particular, the compression spring is designed and arranged in the brewing unit in such a way that it is pressed together by an axial movement of the piston rod housing, which is opposite to the piston movement, and the piston rod housing is moved back into its initial position again by the extension of the compression spring.

[0061] If the piston drive is formed by a water pump of a water treatment plant, the water pump is in particular:

[0062] - hydraulically connected to a water tank via a water supply conduit for obtaining water,

[0063] - is hydraulically connected to the brewing piston via a piston water pipe for displacing the brewing piston, and

[0064] - is hydraulically connected via a brewing water conduit to a brewing chamber for brewing coffee.

[0065] In particular, the control device is designed to switch the water pump between the piston water supply and the brewing water supply.

[0066] In particular, a directional valve such as a 3 / 2-way valve is arranged in the piston water conduit, which is designed and controllable or switchable via a control device so that when the piston water pressure water decreases, the return piston water can be directed away via the discharge conduit while bypassing the water pump.

[0067] In particular, the discharge conduit is a return conduit via which the piston water can flow back into the water tank. The return flow can be achieved in a direct manner via a return conduit leading directly to the water tank, or can be achieved in an indirect manner via a return conduit leading to the supply conduit.

[0068] In particular, a non-return valve for maintaining the built-up piston water pressure is arranged in the piston water conduit, in particular between the water pump and the directional valve.

[0069] In particular, the brewing water conduit leads to a brewing water supply device on the piston tamper. A heating unit such as a thermoblock or a continuous heater is arranged along the brewing water conduit, and the brewing water flowing through the brewing water conduit can be heated via the heating unit.

[0070] In particular, a directional valve such as a 3 / 2-way valve is arranged in the brewing water duct, which valve is designed and can be controlled or switched via the control device so that after the brewing program, residual water flowing back in the direction of the water pump can be conducted away via the discharge duct, i.e. into the drip tray.

[0071] According to a particular embodiment variant, the coffee machine is a portafilter machine and comprises a portafilter device with a brewing filter, also called a portafilter, which is removable from the machine unit. The portafilter device forms a coffee receiving space which, together with a brewing piston advanced into the brewing position and a corresponding piston tamper, forms a brewing chamber.

[0072] “Removable” means in particular that the mobile filter device can be completely separated from the machine unit without being permanently connected to the machine unit.

[0073] In particular, the mobile filter device comprises a handle for manually attaching the mobile filter device to the machine unit and for manually removing the mobile filter device from the machine unit. Attachment and removal of the mobile filter device is in particular achieved in a tool-free manner.

[0074] In particular, the coffee receiving space of the portafilter device can be formed by a filter basket with a brewing filter, which is integrated into the portafilter housing. In particular, the coffee receiving space of the portafilter device can be formed by a filter basket with a brewing filter, which is fixedly established in the portafilter housing. However, the filter basket can also be removable.

[0075] Since according to the invention a movably mounted brewing piston is pushed into the coffee receiving space of the portafilter device for compacting (tamping) the coffee powder and for closing the brewing chamber, no filter baskets of different sizes are required for different amounts of coffee powder.

[0076] The attachment of the portafilter device to the machine unit for starting a brewing program can be achieved via a quick-release fastener, such as a bayonet-type fastener, which is known from the prior art, i.e. by applying and rotating in the portafilter device on the machine unit. However, the portafilter device can also be inserted into the machine unit in a straight line via a linear guide.

[0077] The portable filter device can be removed from the machine unit, in particular for removing coffee grounds after a brewing program. As a supplement, the portable filter unit can also be removed from the machine unit in order to fill the portable filter device with coffee powder.

[0078] However, it is also conceivable that the portable filter device or the coffee receiving space is filled with coffee powder via a grinder integrated into the machine unit or the coffee machine. In particular, this also applies to fully automatic coffee machines.

[0079] This means that the machine unit or the coffee machine may comprise means for conveying and in particular for producing and conveying ground coffee into the coffee receiving space.

[0080] The invention also relates to a method for brewing a coffee beverage with a coffee machine as described above. According to the definition, all types of coffee that can be prepared with a portafilter machine belong to the term "coffee beverage". These are, for example, black coffee, espresso, strong coffee, super espresso, etc. Furthermore, according to the definition, all types of preparation with milk as an addition, such as cappuccino or latte macchiato, belong to the term "coffee beverage". For this purpose, the coffee machine may also include milk preparation means, such as a milk frother.

[0081] For activating a brewing program and in particular also for selecting a coffee preparation type, the coffee machine can comprise an input device, for example with a display.

[0082] The method is characterized in that, in order to perform a brewing program, the brewing piston is pushed in the direction of the coffee receiving space filled with coffee powder by the piston drive, and the locking device is actuated when the brewing position is reached, and the brewing piston is locked relative to the axial movement away from the brewing chamber. During the process of establishing the brewing water pressure by the water pump, the brewing water is delivered to the brewing chamber, and the brewing program is performed.

[0083] If the piston drive is realized via a water pump of the brewing water preparation device, the piston water pressure acting on the brewing piston is established by the water pump, in this way, the brewing piston is pushed in the direction of the coffee receiving space, in particular downwards, in particular opposite to the restoring force of the restoring device, into the brewing position.

[0084] The water pump obtains the (piston) water required to establish the piston water pressure from the water tank via the water supply conduit, and pumps it into the piston water conduit as piston water.

[0085] A piston tamper engaging into the coffee receiving space closes the coffee receiving space, in this way forming a closed brewing chamber.

[0086] The brewing piston acts as a coffee compactor or "tamper" and presses the coffee grounds in the coffee receiving space together. The degree or amount of coffee compaction, which primarily influences the type of coffee preparation, can be set, in particular via a control device.

[0087] Thus, the control device can control the compacting pressure (piston pressure) applied to the coffee powder via the piston drive, respectively the water pump, based on the respective setting of the coffee compaction (the amount or degree of coffee compaction).

[0088] Control of the coffee compaction may be effected on the basis of stored specification values ​​or on the basis of specification values ​​entered or selected via an input device on the machine unit.

[0089] The compacting pressure exerted by the brewing piston on the coffee powder is lower than the brewing water pressure in the brewing chamber, which is exerted by the brewing water on the brewing piston in the opposite direction during the brewing process.

[0090] For this reason, the brewing piston in the brewing position according to the invention is locked with respect to an axial movement which is opposite to the direction of advancement of the brewing piston. Due to this locking, during the brewing process, the piston drive only has to build up a relatively low pressure which is required to compact the coffee, rather than a relatively high pressure which counteracts the brewing water pressure.

[0091] According to the locking device described further above, after the brewing piston has reached the brewing position, the actuating element is moved or displaced in an axial direction opposite to the advancement direction of the brewing piston, in particular upwards, by the piston water pressure. Due to the movement of the actuating element, the at least one locking body is radially displaced towards the brewing piston, in particular towards the piston rod, into the locking position, in this way, the brewing piston is locked. "Radial" in particular also means transversely to the piston axis.

[0092] In the locking position, the at least one locking body engages in a depression on the brewing piston, in particular in a depression on the piston rod.

[0093] For the axial movement of the actuating element, in particular the movably mounted piston rod housing to which the actuating element is coupled or connected is moved or displaced into the actuating position in an axial direction opposite to the advancement direction of the brewing piston, in particular upwards, by the piston water pressure in the pressure chamber, counter to the restoring force of the restoring device.

[0094] As described above, the piston water pressure is maintained during the brewing program, in which way the actuating element or the piston rod housing with the actuating element is also held in the actuated position and thus the locking body is also held in the locked position.

[0095] The locking device according to the invention therefore has the advantage that in the case of a portafilter machine, locking of the brewing piston is not achieved until compaction or pressing (tamping) of the coffee powder in the portafilter device has been achieved. Since the amount of coffee powder and accordingly also the brewing position of the brewing piston can vary along the brewing piston axis depending on the type of preparation,

[0096] In order to build up a brewing water pressure in the brewing chamber, the water pump obtains water from the water tank via a water supply conduit and pumps this water into the brewing water conduit as brewing water.

[0097] For this purpose, in particular, the water pump switches from the piston water supply to the brewing water supply. This is also achieved by the control device. Due to the non-return valve in the piston water line, the piston water pressure built up in the piston water line is maintained despite the switch to the brewing water supply.

[0098] For the purpose of unlocking and moving the brewing piston back into its initial position, the piston water pressure is not reduced until after the brewing program has been completed.

[0099] At the end of the brewing program, the supply of brewing water by the water pump ends, and the brewing water pressure decreases accordingly.By switching the directional valve at the brewing water conduit, the residual water present in the brewing water conduit is discharged into, for example, a drip tray.

[0100] Furthermore, in order to reduce the piston water pressure for the purpose of unlocking and resetting the brewing piston, the directional valve in the piston water conduit is switched via the control device in such a way that the piston water is discharged via the drainage conduit. The piston water is led back into the water tank, in particular, via the drainage conduit designed as a return pipe.

[0101] By reducing the piston water pressure, the actuating element or the piston rod housing with the actuating element is moved from the actuating position back into the initial position due to the restoring force of the restoring means.

[0102] In this way, the locking of the brewing piston by the at least one locking body can be released again and the brewing piston moves back into its initial position via the reset device. The release of the locking is achieved passively by the brewing piston, which moves backwards, thereby forcing the at least one locking body back into the space released by the backwards moving actuating element.

[0103] Individual components or devices, such as water pumps, valves, piston drives or grinders, are in particular controlled by a control device. Control commands can be transmitted to the control device via an input device.

[0104] Thus, as already mentioned above, in particular the piston drive is also controlled via the control device. For example, the amount or degree of coffee compaction can be set via an input device or a preset. The control device then controls the compaction pressure (piston pressure) exerted on the coffee powder via the piston drive based on the corresponding specification of the coffee compaction (degree or amount of coffee compaction).

[0105] The coffee machine according to the invention is characterized by the following advantages:

[0106] - a separate arrangement for coffee compaction, due to a brewing piston which, via a control device and by a piston drive, can be advanced in a controlled manner into the coffee receiving space or into the brewing chamber;

[0107] - Due to the locking, the brewing piston does not move backwards during the brewing program despite the low piston pressure;

[0108] The brewing piston is locked via the already existing drive element.

[0109] The advantages of mobile filter units are in particular:

[0110] - thanks to the movable brewing piston, which allows individual coffee compaction and also allows a different filling of the coffee receiving space with coffee grounds, filter baskets of different sizes are no longer necessary;

[0111] - Due to the movable brewing piston, there is no need to fasten the portafilter device against a (stationary) tamper on the machine unit for tamping the coffee. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] The subject matter of the invention is explained in more detail below by means of specific embodiments represented in the attached drawings. In each case, schematically shown in:

[0113] Figure 1a : A perspective view of a first embodiment of an arrangement of a brewing unit and a grinder as well as a linear guide device of a portafilter machine and a portafilter device, seen obliquely from the front;

[0114] Figure 1b :according to Figure 1a cross-section of the arrangement;

[0115] Figure 1c :Based on observation from the rear Figure 1a Another perspective view of the arrangement;

[0116] Figure 2 : A perspective view of a mobile filter device viewed obliquely from above;

[0117] Figure 3 :Based on observation from below Figure 1a A perspective view of the linear guide device without the movable filter device;

[0118] Figure 4 : Based on Figures 1a to 1c A schematic diagram of a mobile filter machine with an arrangement of

[0119] Figure 5 :Based on observation from below Figures 1a to 1c Perspective view of a grinder. DETAILED DESCRIPTION

[0120] According to Figures 1a to 1cIn a first embodiment of the invention, the coffee machine 1 comprises a brewing unit 10 and a device 30 for producing and conveying ground coffee with a conical grinder 31. A holding and guiding device 40 having a linear guide device 41 is arranged below the brewing unit 10 and the device 30. The linear guide device 41 comprises two guide rails 42a, 42b extending parallel to each other, arranged at a distance from each other, and each guide rail comprising a guide groove 44 for slidably receiving a guide rod 55 on a portable filter device 50.

[0121] Furthermore, the coffee machine 1 comprises a portable filter device 50 having a portable filter housing 54 and a gripping body 53 for holding the portable filter device 50. Two guide rods 55 extending laterally parallel to each other on both sides of a receiving opening 56 are arranged on the outside on the portable filter device housing 54 for insertion into the guide grooves 44 of the guide rails 42a, 42b.

[0122] The brewing unit 10 and the device 30 with the conical grinder 31 are arranged one behind the other along the insertion axis EA, wherein the device 30 with the conical grinder 31 is arranged behind the brewing unit 10 in the insertion direction ER.

[0123] The portable filter device 50 can be pushed into the machine unit 2 of the coffee machine 1 via guide rods 55 which laterally engage in the guide grooves 44 of the guide rails 42a, 42b. The machine unit 2 corresponds to the coffee machine 1 without the portable filter device 50.

[0124] Among other things, the portafilter device 50 can be pushed into the filling position FS in which it is arranged below the device 30, respectively the grinder 31. The holding and guiding device 40 forms an end stop 45 which represents an insertion limit and at the same time ensures an exact positioning of the portafilter device 50 in the filling position FS in order to fill the portafilter device 50 with coffee powder 22. This means that the portafilter device 50 assumes the filling position FS when reaching the stop 45.

[0125] The cone grinder 31 comprises a multi-part housing 35, in which a grinding cone 32 and a grinding ring 33 surrounding the grinding cone 32 are arranged. Starting from the cone base, the grinding cone 32 tapers upward along the cone axis. The grinding ring 33 is rotatably mounted in the housing 35 around the cone axis of the grinding cone 32 via a bearing, such as a ball bearing, and is driven via an electric motor 34. A grinding gap is formed between the grinding ring 33 and the grinding cone 32, into which the coffee beans are fed from above and ground by the grinding ring rotating around the cone axis. The ground coffee powder leaves the grinding gap at the lower end in the cone base area and falls downward due to gravity.

[0126] The grinding cone 32 is arranged in a rigid, ie immovable manner and is connected at its two cone ends via several connecting webs 36a, 36b to the housing 35. Starting from the cone axis, the connecting webs 36a, 36b extend radially outwards towards the housing 35 in a star-shaped manner.

[0127] A plurality of through openings for allowing coffee beans to enter the conical grinder 31 downward in the direction of gravity G are formed at the upper end of the grinding cone (see Figure 1c ).

[0128] A plurality of through openings for allowing coffee powder 22 to pass downwardly from the conical grinder 31 in the direction of gravity G into the coffee receiving space 51 of the mobile filter device 50 are formed at the lower end of the grinding cone (i.e., at the base of the cone) between the connecting webs 36b (see Figure 5 ).

[0129] However, it is not absolutely necessary for the coffee machine to include an integrated grinder as represented in the figures. This relates in particular to portafilter machines. For example, the grinder can also be arranged or attached to the coffee machine in such a way that the portafilter device is already filled with coffee powder before being inserted into the machine unit or before being attached to the machine unit. Furthermore, it is also possible that the coffee machine does not have a grinder and that the coffee powder can be obtained from a separate coffee grinder or supply store.

[0130] The mobile filter device 50 comprises a filter basket 49 which is received in a mobile filter housing 54 with a brewing filter 52 forming the base of the filter basket 49. The filter basket 49 forms a coffee receiving space 51 for receiving coffee powder 22. This is open to the top. Therefore, the filter basket 49 comprises a receiving opening 56 leading to the top. This is located opposite the brewing filter 52. The coffee receiving space 51 is designed in a cylindrical manner, but comprises a circumferential funnel-shaped widening 57 in the region of the receiving opening 56. The filter basket 49 in this embodiment example is fixedly connected to the mobile filter housing 54 and therefore cannot be removed. However, the filter basket 49 may also be removable. The filter basket 49 may likewise be an integral component of the mobile filter housing 54.

[0131] After filling the coffee receiving space 51 of the portafilter 50 with coffee powder 22 , the portafilter 50 is retracted in a linear reverse motion into the brewing position BS via the linear guide 41 . In the brewing position BS, the portafilter 50 is located below the brewing unit 10 .

[0132] As from Figure 2 and Figure 3 As can be seen more clearly in FIG, the linear guide device 41 and the mobile filter device 50 comprise latching means 43, 59 which cooperate with each other and which allow an accurate self-centering positioning of the mobile filter device 50 in the brewing position BS. In the present embodiment example, a latching recess 41 is formed in the guide groove 44 of the guide rails 42a, 42b, into which recess a spring-loaded ball 59 arranged on a guide rod 55 of the mobile filter device 50 engages. The latching recesses 43 each form an entry and exit ramp along the insertion direction ER and opposite to the insertion direction ER. The ramp serves to reduce the force with which the mobile filter device 50 is pushed out or pulled out of the latched position, so that the mobile filter device 50 can be pushed out or pulled out beyond the latched position, or pushed out or pulled out of the latched position again, without requiring too much force.

[0133] Basically, the fastening of the portable filter device can be achieved via conventional quick-release fasteners, such as, for example, bayonet-type fasteners.An integrated grinder is also not mandatory.

[0134] The brewing unit 10 comprises a brewing piston 4 having a piston rod 5 guided in a piston rod housing 7 and a piston tamper 6, which is arranged at the lower end, i.e. facing the mobile filter device 50, and is guided in a piston tamper guide housing 19. The piston tamper guide housing 19 comprises a piston rod guide tube 15, through which the piston rod 5 is guided from the piston rod housing 7 into the piston tamper guide housing 19. The piston axis KA extends perpendicularly to the insertion direction ER or the insertion plane EE of the mobile filter device 50 and therefore also perpendicularly to the receiving opening 56 of the mobile filter device 50.

[0135] To start the brewing process, the brewing piston 4 is moved downwards from its initial position AK by the piston drive 21 in the direction of gravity G towards the coffee receiving space 51 of the portable filter device 50. In this context, the piston tamper 6 moves into the coffee receiving space 51 and compacts or compresses the coffee powder together. In other words, the so-called tamping is performed by the brewing piston 4. The advancement of the brewing piston 4 ends when the brewing position BK is reached. The coffee receiving space 51 closed by the piston tamper 6 now forms the brewing chamber 3.

[0136] The piston drive 21 and also the piston pressure therewith, which in turn is a measure of the compaction of the coffee, is controlled via the control device 20. The piston drive 21 can be an electric drive or a hydraulic drive. With regard to the latter, as explained in more detail below, a hydraulic fluid, such as water, is introduced into the pressure chamber 9 via a supply device 25. The hydraulic drive of the brewing piston 4 can be realized via a water pump 62 of the brewing water preparation device 60, which will be described below in detail. Figure 4 Further explanation.

[0137] The coffee machine or machine unit 2 further comprises a brewing water preparation device 60 having a water tank 61, a water pump 62 and a heating unit 63 for supplying hot water under pressure into the brewing chamber 3 (see also Figure 4 ). Hot brewing water is introduced into the brewing chamber 3 under pressure via a brewing water supply 18 which is guided through the piston tamper 6.

[0138] The portafilter device 50 comprises a coffee outlet opening 58 arranged below the brewing filter 52. Coffee brewed in the brewing chamber 3 and compacted through the brewing filter 52 flows downwardly through the brewing filter 52, for example into a beverage vessel (not shown).

[0139] The brewing piston 4 interacts with a return spring 8. In the present embodiment, this spring corresponds to a compression spring 8 in the form of a helical spring surrounding the piston rod 5. After the brewing program is completed, as the piston pressure decreases, the compression spring 8, which is pressed together when the brewing piston 4 is advanced toward the portable filter device 50, presses the brewing piston 4 back into its initial position AK again. Given a piston drive 21, such as an electric drive that actively moves the brewing piston 4 backwards, a return means, such as a return spring, is not necessarily required.

[0140] The brewing piston 4 further comprises a piston guide sleeve 24, by which the brewing piston 4 is axially guided in the piston rod housing 7. The piston guide sleeve 24 is arranged in an upper end section of the brewing piston 4 towards the pressure chamber 9.

[0141] According to the present embodiment, the brewing piston 4 is locked in the brewing position BK by means of the locking device 11 with respect to the axial direction opposite to the advancement direction of the brewing piston 4. The locking serves, among other things, to release the piston drive 21. Therefore, the piston pressure applied by the piston drive 21 on the brewing piston 4 for compacting the coffee powder 22 is significantly lower than the brewing water pressure, which is established in the brewing chamber by the water pump 62 of the brewing water preparation device 60 and acts on the brewing piston 4 as a counterpressure. Due to the locking of the brewing piston 4 during the brewing process, it is not necessary to establish a counterpressure corresponding to the brewing water pressure by means of the piston drive. However, the locking device 11 is not absolutely necessary. Furthermore, the piston drive 21 itself can also achieve locking.

[0142] according to Figures 1a to 1c The embodiment of FIG. 4 shows a special embodiment of a locking device, which is characterized in that the locking device is also activated via the piston drive 21 .

[0143] In the present case, the piston drive 21 applies hydraulic pressure to the brewing piston 4 via a hydraulic fluid and via a hydraulic pump. To this end, the hydraulic fluid is introduced via a supply device 25, such as a piston water supply device, into the pressure chamber 9, which is delimited, among other things, by the movable brewing piston 4. The pressure chamber 9 is Figure 1b The pressure chamber 9 does not extend spatially downwards into the brewing position BK until the brewing piston 4 has been moved downwards out of its starting position AK.

[0144] If through Figure 4 Explained in more detail, the hydraulic pump may also correspond to the water pump 62 of the brewing water preparation device 60 , and the hydraulic fluid may be water from the water tank 61 of the brewing water preparation device 60 .

[0145] Due to the pressure of the hydraulic fluid (eg water) flowing into the pressure chamber 9 , the brewing piston 4 is moved downwards from its starting position AK into the brewing position BK counter to the restoring force of the restoring spring 8 in the direction of the portable filter unit 50 .

[0146] The pressure chamber 9 is delimited to the top by the piston rod housing 7. The piston rod housing 7 is mounted axially movably relative to the piston tamper guide housing 19 via two connecting screws 23 and is therefore mounted axially movably relative to the piston rod guide tube 15 along the connecting screws 23. The connecting screws 23 thus form a guide section, in particular without a thread, for axially guiding the axially movable piston rod housing 7. The piston rod housing 7 is held in the initial position via two compression springs 17, which press the piston rod housing 7 downwards. The compression springs 17 are designed as helical springs and each surrounds the connecting screws 23.

[0147] The downward axial movement of the brewing piston 4 is completed when the brewing position BK is reached. The further increased pressure in the pressure chamber 9 now exerts a corresponding force on the piston rod housing 7, which in this way moves the piston rod housing 7 slightly upwards in the opposite direction to the piston movement, counter to the restoring force of the compression spring 17.

[0148] The annular actuating element 12 of the locking device 11, which is likewise moved upwards and surrounds the piston rod guide tube 15, is also connected to the piston rod housing 7. The actuating element 12 forms a radial distance to the piston rod guide tube 15 in the upper section, in this way creating an annular cavity or gap. In the lower section, the actuating element 12 is in sliding contact with the piston rod guide tube 15 and is supported thereon. The upper section and the lower section merge into each other via a guide bevel.

[0149] The piston rod guide tube 15 comprises, at the level of the actuating element 12 , a radial through-opening 14 , in which the ball 13 is movably mounted.

[0150] The piston rod 4 comprises a plurality of grooves 16 which are arranged along the piston axis KA and each at an annular periphery and into which the balls 13 can engage.

[0151] In the unlocked position, the piston rod housing 7 and together with the actuating element 12 are held in a lower initial position by the restoring force of the compression spring 17. The upper section of the actuating element 12 with the annular cavity or gap is located at the level of the radial through-opening 14. The ball 13 is retracted from the radial through-opening 14 and engages in the annular cavity.

[0152] If the brewing piston 4 now reaches the brewing position BK, as mentioned above, the piston rod housing 7 is slightly lifted in the axial direction together with the actuating element 12. In this way, the lower section of the actuating element 12 is moved upwards together with the annular gap, in which way, due to the upward movement of the lower section, the ball 13 is moved radially inwards back into the through-opening 14. The guiding bevel between the upper section and the lower section ensures that the ball 13 is not stuck by the actuating element 12, but is moved uniformly into the through-opening 14.

[0153] The ball 13 which has now moved back into the radial through-opening 14 on the other side engages in the groove 16 on the piston rod 15 and effects the locking of the brewing piston 4 in the brewing position BK. The ball 13 thus acts as a locking body.

[0154] As long as the hydraulic pressure in the pressure chamber 9 is able to press the piston rod housing 7 upwards against the restoring force of the compression spring 17 , the locking is maintained.

[0155] After the brewing program is completed, the pressure in the pressure chamber 9 is reduced, in which way the piston rod housing 7 moves downwards together with the actuating element 12 back into the initial position due to the restoring force of the compression spring 17. The upper section of the actuating element 12 together with the annular gap between the actuating element 12 and the piston rod guide tube 15 is again located at the height of the radial through-opening 14.

[0156] Due to the reduced pressure in the pressure chamber 9, the restoring force exerted by the compression spring 8 on the brewing piston 4 again dominates. Due to the pressing force of the compression spring 8 or due to the upward movement of the brewing piston 4 by the compression spring 8, the ball 13 moves out of the groove 16, back into the radial through-opening 14 and into the annular gap located behind it.

[0157] The locking is released and, due to the restoring force of the compression spring 8 , the brewing piston 4 springs back upwards into the initial position AK.

[0158] Figure 4 A particular further development of the coffee machine 1 is shown, which is characterized in that the brewing piston 4 is driven, that is to say advanced in the brewing position BK, by a water pump 62 of a brewing water preparation device 60. The water pump 62 receives water from a water tank 61 via a water supply duct 64. The water pump 62 is connected to a brewing water supply 18 on the piston tamper 6 via a brewing water duct 66. A heating unit 63, i.e. a thermal module or a continuous heater, is arranged along the brewing water duct 66 for heating the brewing water flowing through the brewing water duct 66. The water pump 62 pumps water under pressure from the water tank 61 via the brewing water duct 66 into the brewing chamber 3. The brewing water is heated by the heating unit 63 on its way through the brewing water duct 66.

[0159] A 3 / 2-way valve 72 is arranged on the brewing water duct 66 , said valve comprising a further connection for draining residual water after a brewing process into a catch container such as a drip tray. The 3 / 2-way valve 72 is switched via the control device 20 .

[0160] The water pump 62 is also connected to a piston water conduit 65, via which water is pumped from the water tank 61 into the pressure chamber 9 in the piston rod housing 7 (see Figure 1b ) for advancing the brewing piston 4 from the initial position AK into the brewing position BK.

[0161] The piston water conduit 65 includes a check valve 71 which prevents water from flowing back from the pressure chamber 9 into the water pump 62. In addition, a 3 / 2-way valve 70 is arranged in the piston water conduit 65 between the check valve 71 and the pressure chamber 9. A return water conduit 67 is connected to the 3 / 2-way valve 70, via which the piston water can be led back into the water tank 61. A pressure gauge 73 for monitoring the pressure in the pressure chamber 9 is located on the piston water conduit 65.

[0162] In order to advance the brewing piston 4 from the initial position AK into the brewing position BK, the water pump 62 pumps water from the water tank 61 into the piston water line 65 and builds up a piston pressure specified by the control device 20 .

[0163] After the brewing piston 4 has reached its brewing position BK and is locked, the water pump 62 during the heating process pumps water out of the water tank 61 through the brewing water duct 66 into the brewing chamber 3 and builds up a brewing pressure which is usually greater than the piston pressure.

[0164] The water pump 62 is switched between the piston water line 65 and the brewing water line 66 or between the piston water supply and the brewing water supply via the control device 20. The non-return valve 71 in the piston water line 65 prevents a pressure loss in the pressure chamber 9 when the water pump 62 is switched from the piston water line 65 to the brewing water line 66.

[0165] The pressure in the brewing water duct 66 is released at the end of the brewing program and the 3 / 2-way valve is switched by the control device 20 so that the remaining water is discharged into a catch container (not shown).

[0166] Furthermore, the pressure in the piston water duct 65 is also released, and the 3 / 2-way valve 70 is switched so that the piston water is directed back into the water tank 61 via the return water supply duct 67 .

Claims

1. A coffee machine (1), comprising a machine unit (2), the machine unit having: - a control device (20) for controlling the coffee machine (1), a brewing piston (4) which is mounted so as to be movable between a home position (AK) and a brewing position (BK), a piston drive (62) controllable by the control device (20) for moving the brewing piston (4) from the initial position (AK) into the brewing position (BK) and having a water preparation device (60) having a water tank (61), a water pump (62) and a heating unit (63) for producing hot brewing water under pressure and conveying it to the brewing chamber (3), Features The coffee machine comprises a locking device (11) having at least one locking body (13) for locking the brewing piston (4) in the brewing position (BK).

2. The coffee machine (1) according to claim 1, characterized in that The locking device (11) is actuatable via the piston driver (62).

3. The coffee machine (1) according to claim 1 or 2, characterized in that: The piston drive (62) is a hydraulic drive.

4. The coffee machine (1) according to any one of claims 1 to 3, characterized in that The piston drive (62) is formed by a water pump (62) of the water preparation device (60).

5. The coffee machine (1) according to any one of claims 1 to 4, characterized in that The locking device (11) can be actuated by a water pump (62) of the water preparation device (60).

6. The coffee machine (1) according to any one of claims 1 to 5, characterized in that The locking device (11) comprises an actuating element (12) which is movable parallel to a piston axis (KA) of the brewing piston (4), and the at least one locking body (13) is movable via the actuating element (12) towards the brewing piston (4) into a locking position.

7. The coffee machine (1) according to any one of claims 2 to 6, characterized in that The coffee machine (1) is designed so that, in order to start a brewing program, the piston drive (62) moves the brewing piston (4) into a brewing position in a first step and, after reaching the brewing position, actuates a locking device (11) during the locking process of the brewing piston (4) in a second step.

8. The coffee machine (1) according to any one of claims 2 to 7, characterized in that The coffee machine (1) is designed so that, in order to start a brewing program, the piston drive (62) moves the brewing piston (4) into the brewing position in a first step while compacting the coffee powder by applying a compaction force, and in a second step, when the maximum compaction force is reached and the brewing position is assumed, the locking device (11) is actuated during the locking process of the brewing piston (4).

9. The coffee machine (1) according to any one of claims 2 to 8, characterized in that The machine unit (1) comprises a piston rod housing (7), which is mounted so as to be movably along a piston axis (KA) and interacts with an actuating element (12) of a locking device (11), wherein the piston rod housing (7) and the brewing piston (4) are designed and interact with each other in such a way that in a first step, the piston drive (62) advances the brewing piston (4) in an axial direction towards the brewing chamber (3) into a brewing position (BK), and then in a second step, during the actuation of the locking device (11), the piston rod housing (7) is displaced in the opposite axial direction.

10. The coffee machine (1) according to any one of claims 3 to 9, characterized in that The machine unit (1) comprises a piston rod housing (7), which is mounted axially movably along a piston axis (KA) and interacts with an actuating element (12) of a locking device (11) and forms a pressure chamber (9) together with a brewing piston (4), wherein the piston rod housing (7) and the brewing piston (4) are designed and interact with each other in such a way that a piston fluid pressure, in particular a piston water pressure, generated in the pressure chamber (9) pushes the brewing piston (4) in an axial direction towards the brewing chamber (3) into a brewing position (BK) and subsequently displaces the piston rod housing (7) in the opposite axial direction during actuation of the locking device (11).

11. The coffee machine (1) according to any one of claims 1 to 10, characterized in that The at least one locking body (13) is a ball (13) which is guided in a radial opening (14) of a piston rod guide tube (15) and which engages in a recess (16) on the brewing piston (4) in the locking position.

12. The coffee machine (1) according to any one of claims 1 to 11, characterized in that The coffee machine (1) comprises a mobile filter device (50) having a coffee receiving space (51) and a brewing filter (52), the mobile filter device being removable from a machine unit (2), wherein the coffee receiving space (51) of the mobile filter device (50) forms a brewing chamber (3) together with a brewing piston (4) advanced into a brewing position (BK).

13. The coffee machine (1) according to any one of claims 3 to 12, characterized in that The brewing piston (4) interacts with a reset device (8), in particular a reset spring, by means of which the brewing piston (4) can be moved back from the brewing position (BK) into the initial position (AK) after a reduction in piston fluid pressure, in particular piston water pressure.

14. The coffee machine (1) according to any one of claims 10 to 13, characterized in that The piston rod housing (7) interacts with the reset device (17), in particular with at least one reset spring, by means of which the piston rod housing (7) can be moved back into its initial position in the direction of the brewing chamber (3) after a reduction in the piston fluid pressure, in particular the piston water pressure.

15. The coffee machine (1) according to any one of claims 3 to 14, characterized in that The water pump (62) of the water preparation device (60): - hydraulically connected to a water tank (61) via a water supply conduit (64) for obtaining water, - is hydraulically connected to the brewing piston (4) via a piston water conduit (65) for displacing the brewing piston (4), and - is hydraulically connected to a brewing chamber (3) via a brewing water conduit (66) for brewing coffee.

16. The coffee machine (1) according to claim 15, characterized in that A directional valve (70) is arranged in the piston water conduit (65), and the valve is designed and controllable via the control device (20) so that when the piston water pressure water decreases, the returning piston water can be guided away via the discharge conduit (67) while bypassing the water pump (62).

17. The coffee machine (1) according to claim 16, characterized in that The discharge conduit (67) is a return conduit (67), through which the returned piston water can flow back into the water supply conduit (64) or the water tank (61) again.

18. The coffee machine (1) according to any one of claims 15 to 17, characterized in that A non-return valve (71) for maintaining the built-up piston water pressure is arranged in the piston water conduit (65), in particular between the water pump (62) and the directional valve (70).

19. The coffee machine according to any one of claims 15 to 18, characterized in that A heating unit (63) for heating brewing water is arranged at the brewing water conduit (66).

20. A method for brewing coffee using a coffee machine (1) according to any one of claims 1 to 19, Features To perform a brewing process, the brewing piston (4) is advanced by means of a piston drive (62) in the direction of a coffee receiving space (51) filled with coffee powder, and When the brewing position (BK) is reached, the locking device (11) is actuated and locks the brewing piston (4) with respect to axial movement away from the brewing chamber (3), and During the process of building up the brewing water pressure, the brewing water is delivered to the brewing chamber (3) by the water pump (62), and the brewing process is performed.

21. The method according to claim 20, characterized in that A piston water pressure acting on the brewing piston (4) is established by the water pump (62), and the brewing piston (4) is pushed in the direction of the coffee receiving space (51) by the piston water pressure.

22. The method according to any one of claims 20 to 21, characterized in that The brewing piston (4) acts as a coffee compactor and presses the coffee powder in the coffee receiving space (51) together.

23. The method according to any one of claims 20 to 22, characterized in that During the brewing process, the compacting pressure exerted by the brewing piston (4) on the coffee powder is lower than the brewing water pressure exerted on the brewing piston (4) in the opposite direction.

24. The method according to any one of claims 21 to 23, characterized in that The water pump (62) obtains water for establishing piston water pressure from the water tank (61) via the water supply pipe (64), and pumps the water into the piston water pipe (65) as piston water.

25. The method according to any one of claims 20 to 24, characterized in that In order to build up brewing water pressure in the brewing chamber (3), the water pump (62) obtains water from the water tank (61) via the water supply conduit (64) and pumps the water into the brewing water conduit (66) as brewing water.

26. The method according to any one of claims 21 to 25, characterized in that The piston water pressure generated is maintained until the end of the brewing program and, after completion of the brewing program, is reduced again for the purpose of releasing the lock and moving the brewing piston (4) back into its initial position (AK).

27. The method according to claims 21 to 26, characterized in that The reduction of the piston water pressure is achieved by draining the piston water through the drain conduit (67).

28. The method according to any one of claims 21 to 27, characterized in that The piston water pressure is reduced by directing the piston water back to the water supply conduit (64) or the water tank (61) via the return conduit (67).

29. The method according to claims 21 to 28, characterized in that The directional valve (70) is switched via the control device (20) for reducing the piston water pressure and for discharging or returning the piston water.

30. The method according to any one of claims 21 to 29, characterized in that At the end of the brewing program, the piston water pressure is reduced and as a result, the locking is released and the brewing piston (4) is subsequently moved back into its initial position (AK) via the resetting means (8).

31. The method according to any one of claims 20 to 30, characterized in that The control device (20) switches the water pump (60) between the piston water supply device and the brewing water supply device.

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