COFFEE MACHINE AND METHOD FOR PREPARING A COFFEE DRINK

Description

[0001] The invention lies in the field of coffee machines and relates to a coffee machine with a machine unit and with a portafilter device removable from the machine unit for producing, in particular brewing, a coffee beverage according to the preamble of independent claim 1. Furthermore, the invention also relates to a method for producing, in particular brewing, a coffee beverage.

[0002] Coffee machines with portafilters, or portafilters for short, are also known as portafilter machines. Portafilter machines are widely used among coffee machines. They are available for both private households and commercial use. Portafilter machines operate semi-automatically, as certain steps are performed manually. According to current technology, the portafilter, which holds the ground coffee, is manually removed from the coffee machine both for filling it with coffee grounds before brewing and for removing the coffee grounds after brewing.

[0003] In this description, "coffee powder" refers specifically to ground coffee, i.e., coffee flour. "Coffee residue" refers specifically to the residue left after brewing, also known as coffee grounds.

[0004] With portafilter machines, the coffee grounds are filled into the portafilter outside the coffee machine. Some portafilter machines have an integrated grinder. In this case, the portafilter, which is separate from the coffee machine, is held under the grinder's dispensing opening to be filled with coffee grounds and then manually attached to the coffee machine in the brewing position.

[0005] This is in contrast to fully automatic coffee machines, in which the coffee powder goes directly from an integrated grinder into the brewing chamber and the coffee grounds are automatically ejected into an integrated collection container after the brewing process has ended.

[0006] The portafilter is typically attached to the coffee machine via a quick-release mechanism. Common portafilters feature a housing with several radially outward-projecting protrusions that engage with a guide groove on the machine's connection section, forming a bayonet-like fit between the portafilter and the connection section. To attach the portafilter to the coffee machine, it is placed against the connection section from below, ensuring the protrusions engage with the guide groove. The portafilter is then secured to the coffee machine by twisting it with the handle.

[0007] This type of locking mechanism has the disadvantage that attaching the portafilter is quite cumbersome and difficult. The portafilter must be positioned at the correct angle on the connection section from below so that the protrusions engage with the guide. Furthermore, securing the portafilter by twisting requires considerable force. If the guide is dirty, for example with coffee residue, the portafilter may not be able to be secured in the desired position.

[0008] EP 3 954 256 Al, for example, describes a portafilter machine with a portafilter as known from the prior art.

[0009] The tamping of the coffee grounds in the portafilter's coffee chamber, which precedes the brewing process and is particularly important for preparing espresso with crema, is achieved in certain portafilter machines by pressing the portafilter upwards against a stationary piston when attaching it to the coffee machine. These machines typically use different filter baskets, allowing the amount of coffee grounds used for brewing to be varied.

[0010] However, there are also portafilter machines that have a movable brewing piston for pressing down the coffee powder, the so-called "tamping", which can be pressed down towards the portafilter via a hand lever.

[0011] German patent application DE 20 2020 100937 U1 discloses a coffee machine with a portafilter and a movably mounted brewing piston. The portafilter contains a container for holding ground coffee. The coffee machine also includes linear guides in which lateral projections on the portafilter slide. The portafilter can be pushed via the linear guides into an end position in which the brewing piston is located above the container of the portafilter.

[0012] It is now an object of the present invention to propose a coffee machine with a portafilter device which allows the portafilter device to be attached to the coffee machine easily and quickly.

[0013] Furthermore, it is an object of the present invention to propose a coffee machine which enables a defined tamping of the coffee powder even with different filling of the portafilter with coffee powder and without the use of filter inserts of different sizes.

[0014] Another task is to propose a coffee machine that ensures easy, quick and, in particular, safe filling of the portafilter with coffee powder.

[0015] Another task is to propose a coffee machine with a grinder that allows for residue-free changes in coffee type.

[0016] At least one problem is solved by the features of the independent claims. The dependent claims, the description, and the figures contain particular embodiments and further developments of the invention.

[0017] The coffee machine comprises a machine unit and a portafilter assembly, detachable from the machine unit, with a coffee hopper and a brewing screen. The machine unit includes a movable brewing piston, a brewing water preparation unit for generating and dispensing hot water under pressure into the coffee hopper of the portafilter assembly, and a holding and guiding device for attaching and securing the portafilter assembly to the machine unit.

[0018] "Removable" means, in particular, that the portafilter assembly can be completely detached from the machine unit without any permanent connection. The portafilter assembly can be attached to or removed from the machine unit using a handle. Attaching and removing the portafilter assembly is done without tools.

[0019] The portafilter unit is removable from the machine unit, particularly for removing the coffee grounds after brewing. Additionally, the portafilter unit can also be removed from the machine unit for filling it with ground coffee.

[0020] The holding and guiding device includes a linear guide device for linear, i.e. straight, insertion of the portafilter device into the machine unit.

[0021] The portafilter device can also be pulled out of the machine unit again by a corresponding linear, i.e. straight, counter-movement via the linear guide device.

[0022] The linear guide device includes, in particular, two spaced-apart, parallel guide contours, such as guide rails. The guide contours can form a guide slot or a guide channel.

[0023] The linear guide device is arranged in particular below a brewing unit and optionally below a device for dispensing coffee powder, in particular for producing and dispensing coffee powder.

[0024] The linear guide device can be arranged on a support plate or be part of a support plate. The brewing unit and, optionally, the device for dispensing coffee powder, in particular for producing and dispensing coffee powder, can be arranged or attached to the support plate.

[0025] The portafilter assembly includes, in particular, a portafilter housing in which the coffee receiving chamber is arranged. Guide elements, in particular at least two opposing guide elements, are arranged laterally on the portafilter housing, which, in conjunction with the linear guide device, form a linear guide. The guide elements are, in particular, designed as lateral guide rails, which, in particular, run parallel to each other.

[0026] The linear movement performed via the linear guide device is particularly horizontal.

[0027] The portafilter assembly can be inserted into the machine unit, particularly along or parallel to an insertion plane, via the linear guide device. The insertion plane is particularly horizontally oriented.

[0028] However, the horizontal movement or insertion plane requires that the coffee machine or machine unit is supported on a horizontal surface.

[0029] The linear guide is in particular a sliding guide in which the guide bodies slide in the linear guide device or in the guide contours.

[0030] The portafilter assembly, held in the linear guide device, can be moved within the machine unit into a brewing position for brewing coffee. The portafilter assembly can be moved into a brewing position via the linear guide device, specifically in a linear motion.

[0031] The brewing position is formed within the machine unit, particularly below a brewing unit. It corresponds specifically to the position that the portafilter assembly assumes or has during the brewing process.

[0032] According to the invention, the machine unit includes a device for dispensing and, in particular, for producing and dispensing coffee powder into the coffee intake chamber of the portafilter device.

[0033] The portafilter unit, which is held in the linear guide device, can be moved into a filling position in the machine unit for dispensing coffee powder into the coffee receiving chamber of the portafilter unit.

[0034] The portafilter device can be pushed or moved via the linear guide device, in particular in a linear movement, into a filling position in which the coffee receiving chamber of the portafilter device can be filled with coffee powder.

[0035] The filling position is different from the brewing position. In particular, the filling position and the brewing position lie in a common horizontal plane.

[0036] The filling position is typically located below a grinder within the machine unit. However, it can also be located below a coffee powder dispensing unit. This dispensing unit may include a container for storing coffee powder, which must be filled manually.

[0037] The portafilter device, which is held in the linear guide device, is movable in the machine unit between the filling position and the brewing position.

[0038] The portafilter unit, which is inserted linearly into the machine unit via the linear guide device, is movable within the machine unit between the filling position and the brewing position.

[0039] The portafilter unit is movable in the machine unit, particularly in one plane, especially in a horizontal plane between the filling position and the brewing position.

[0040] The movement of the portafilter assembly between the filling position and the brewing position can be linear. This is particularly the case when the portafilter assembly is moved within the linear guide device between the filling position and the brewing position.

[0041] The movement of the portafilter assembly between the filling position and the brewing position can be a pivoting movement, as described in more detail below.

[0042] The portafilter unit is held in the linear guide device during the movement between the filling position and the brewing position in the machine unit, via which the portafilter unit has already been inserted into the machine unit.

[0043] According to a first design variant, the brewing position and the filling position are arranged one behind the other along the insertion axis of the portafilter device.

[0044] The filling position is located in the insertion direction, specifically after the brewing position. To initiate a brewing process, the portafilter is inserted into the machine unit in a linear motion until it reaches the filling position. After filling the portafilter with coffee grounds, it is retracted into the brewing position in a linear counter-movement. Once the brewing process is complete, the portafilter is completely withdrawn from the machine unit in a continuation of the linear counter-movement.

[0045] Alternatively, the filling position can also be located before the brewing position in the insertion direction. To initiate a brewing process, the portafilter is inserted into the machine unit in a linear motion until it reaches the filling position. After filling the portafilter with ground coffee, it is pushed further into the brewing position in a continuation of the linear insertion motion. After the brewing process is complete, the portafilter is pulled completely out of the machine unit in a linear counter-movement, past the filling position.

[0046] According to this design variant, the linear guide device is in particular fixed or stationary on the machine unit.

[0047] According to a second embodiment, the linear guide device is pivotably mounted on the machine unit via a pivot axis arranged perpendicular to the insertion plane. The portafilter assembly, inserted into the machine unit via the linear guide device, is pivotably mounted together with the linear guide device between a filling position and the brewing position.

[0048] In this case, the portafilter unit can be inserted into a working position relative to the linear guide device, in which the portafilter unit can be pivoted relative to the device for dispensing or producing and dispensing coffee powder and to the brewing unit between the filling position and the brewing position.

[0049] According to a further development of the invention, locking means can be provided which enable the portafilter device to assume a locking position in one or more of the following positions: Filling position (first version variant); Brewing position (first version variant); Working position (second version variant).

[0050] Locking devices can be provided which are designed so that the positioning of the portafilter device in the brewing position is achieved by assuming a locking position.

[0051] The locking mechanisms are designed to position the portafilter assembly in the corresponding position by engaging a detent. In particular, the locking mechanisms ensure precise positioning in the corresponding position. Specifically, the locking mechanisms ensure self-centering of the portafilter assembly in the corresponding position.

[0052] The locking mechanisms are specifically designed so that the portafilter assembly can be pushed further or pulled back beyond the locking position, if necessary by requiring increased force.

[0053] The locking devices can be, for example, spring-loaded push buttons or balls that engage in a recess in the linear guide device in the corresponding position during the linear movement of the portafilter assembly. The spring-loaded buttons or balls can be arranged, for example, on the portafilter assembly, particularly on the guide bodies. The recesses can be arranged, for example, in the guide rails, guide slots, or guide channels.

[0054] The recesses feature ramps, particularly in and against the insertion direction, which facilitate moving the portafilter assembly out of the detent position in both directions, or reduce the effort required. This is especially relevant if the portafilter assembly is to be moved beyond the detent position.

[0055] According to a further development of the invention, stop means can be provided in the machine unit, in particular on the holding and guiding device or linear guide device, as insertion limits, by means of which the sieve carrier device can be positioned in one of the following positions: Filling position (first version variant); Brewing position (first version variant); Working position (second version variant).

[0056] Thus, lifting devices can be provided on which the portafilter device can be positioned in the filling position.

[0057] The lifting devices ensure, in particular, precise positioning in the corresponding position by striking the portafilter assembly against the lifting devices.

[0058] The portafilter device includes, in particular, a handle for manually inserting the portafilter device into the machine unit and for manually pulling it out of the machine unit.

[0059] The coffee intake chamber of the portafilter can be formed, in particular, by a filter basket with a brewing screen integrated into the portafilter housing. Thus, the coffee intake chamber of the portafilter can be formed by a filter basket with a brewing screen permanently installed in the portafilter housing. However, the filter basket can also be removable.

[0060] Since, according to the present invention, the movably mounted brewing piston is driven into the coffee receiving chamber of the portafilter device for pressing (tamping) the coffee powder and closing the brewing chamber, different sized filter inserts for different quantities of coffee powder are not necessary.

[0061] The brewing piston is, in particular, part of a brewing unit integrated into the machine unit and comprises a piston plunger. The piston plunger is located on the brewing side. The piston plunger is, in particular, connected to a piston shaft, which is guided in a piston shaft housing. The brewing piston and piston shaft housing are, in particular, part of the brewing unit within the machine unit.

[0062] The brewing unit, together with the portafilter assembly, forms a brewing group.

[0063] The brewing piston is driven. The drive can be manual, e.g. via a lever mechanism, or via a control device using a piston drive.

[0064] The piston drive can include an electric motor. In this way, the brewing piston can be driven by the electric motor via a drive spindle.

[0065] The piston drive can also include a hydraulic drive, which uses a hydraulic fluid, such as water, to build up hydraulic pressure in a pressure chamber, pushing the brewing piston into the brewing position. The hydraulic pressure can be, for example, between 2 and 3 bar.

[0066] The hydraulic drive can be the water pump of a brewing water preparation unit within the machine. The hydraulic fluid is water from the brewing water preparation unit's water tank. The drive is achieved via hydraulic pressure generated by the water pump, which acts on the brewing piston.

[0067] The coffee intake chamber, or the coffee intake forming the coffee intake chamber, is arranged in a fixed or immovable position within the machine unit, particularly during the brewing process. The same applies accordingly to the portafilter assembly.

[0068] The coffee intake chamber of the portafilter device forms a funnel-shaped extension in the area of ​​a receiving opening towards the outside.

[0069] The intake opening corresponds to the opening that faces the brewing unit of the machine, and through which the brewing piston, with its piston plunger, engages in the coffee intake chamber, forming the brewing chamber. The coffee intake chamber is also typically filled with ground coffee through this intake opening.

[0070] The funnel-shaped extension causes the portafilter assembly to self-center in the brewing position by means of the piston plunger of the brewing piston, which moves downwards and engages in the coffee receiving chamber.

[0071] The means for producing and dispensing coffee powder include, in particular, a grinding mechanism, such as a conical burr grinder.

[0072] The conical grinding mill is characterized by an internal, stationary grinding cone and an external, driven grinding ring that surrounds the grinding cone. The grinding ring is driven, in particular, by a drive mechanism such as an electric motor. To drive the grinding ring, a drive element, such as a drive spindle, and the outer surface of the grinding ring form a drive pairing. The outer surface of the grinding ring has a roughness pattern, such as ribbing or serrations.

[0073] The conical grinder is designed and arranged in the machine unit in such a way that the ground coffee powder falls from the conical grinder downwards by gravity into the coffee receiving chamber of the portafilter unit inserted into the filling position in the machine unit.

[0074] In conventional conical burr grinders, where the grinding cone is driven, the coffee grounds are guided downwards at an angle via a sloping guide surface. This guide surface is necessary, among other reasons, because space constraints prevent the coffee grounds from being guided vertically downwards. This is due, in part, to the drive mechanism of the grinding cone, which is located below the cone, extending along its axis.

[0075] Small amounts of coffee grounds remain on the guide surface after each grinding process, meaning that during the first grinding after changing coffee beans, coffee grounds from the previous grinding process still end up in the portafilter. This disadvantage is eliminated by the conical burr grinder used here.

[0076] The grinding ring and the grinding cone are arranged in a housing. The housing can be one or more parts. The grinding ring is rotatably mounted in the housing, for example, by a bearing such as a ball bearing.

[0077] The grinding cone tapers upwards from its base. The stationary grinding cone is connected to the housing, particularly via connecting webs. The cone axis of the grinding cone is vertically oriented.

[0078] The grinding cone is connected to the housing, particularly at both ends, via connecting webs.

[0079] The connecting webs run perpendicular to the (geometric) cone axis of the grinding cone. For example, the connecting webs can extend radially or in a star-shaped pattern outwards from the cone axis towards the housing.

[0080] At the upper end of the grinding cone, one or more openings are formed between the connecting ribs to allow coffee beans to pass downwards into the grinding mechanism.

[0081] At the lower end of the grinding cone, i.e. at the base of the cone, one or more passage openings are formed between the connecting ribs to allow coffee powder to pass downwards from the grinder.

[0082] According to one embodiment, the conical grinding mechanism contains a housing that accommodates the grinding cone and the grinding ring, with the stationary grinding cone being connected to the housing via connecting webs.

[0083] The invention further relates to a method for brewing a coffee beverage with a coffee machine as described above. By definition, a coffee beverage includes all types of coffee preparation possible with a portafilter machine. These are, for example, black coffee, espresso, espresso lungo, ristretto, etc. Furthermore, by definition, coffee beverages also include preparations with added milk, such as cappuccino or latte macchiato. The coffee machine may also include a milk preparation device, such as a milk frother.

[0084] The coffee machine contains an input device, e.g. with a display, to trigger a brewing process and in particular to select the coffee preparation method.

[0085] The machine unit also includes a control device for operating the individual units or devices, such as water pump, valves, possibly piston drive, grinding mechanism or input device, etc.

[0086] The piston drive is also controlled by the control unit. The input device or presets allow the user to define parameters such as the amount or degree of coffee tamp. Based on these settings, the control unit then regulates the pressure (piston pressure) applied to the coffee grounds via the piston drive.

[0087] The process is characterized by the fact that the portafilter device for brewing coffee is inserted into the machine unit via the linear guide by means of a linear movement and, after completion of the brewing process, is pulled out of the machine unit again in a linear counter-movement.

[0088] The portafilter unit can be filled with coffee powder outside the machine unit in preparation for the brewing process and, when filled, inserted into the machine unit in a linear movement into the brewing position.

[0089] Alternatively, the portafilter assembly can also be inserted empty into the machine unit in a linear motion. Filling takes place within the machine unit via integrated dispensing means, in particular for the production and dispensing of coffee grounds.

[0090] According to the first embodiment, in which the filling and brewing positions are arranged one after the other along the insertion axis, the portafilter assembly for brewing coffee is first inserted into a filling position via the linear guide in a linear movement and, after the coffee intake chamber has been filled with coffee grounds, retracted into a brewing position in a linear counter-movement. In this case, the filling position is located after the brewing position in the insertion direction.

[0091] Alternatively, i.e., if the filling position is located in the insertion direction before the brewing position, the portafilter device for brewing coffee can first be inserted into the filling position via the linear guide in a linear movement and, after filling the coffee receiving chamber with coffee powder, pushed further into the brewing position in a continuation of the linear insertion movement.

[0092] According to the second variant, in which the portafilter assembly is pivotable together with the linear guide, the portafilter assembly is inserted into the machine unit and into a working position relative to the linear guide in a linear movement for brewing coffee. To fill the coffee chamber with ground coffee and to brew the coffee, the portafilter assembly, which is in its working position relative to the linear guide, is pivoted together with the linear guide between a filling position and a brewing position relative to the dispensing device (or the device for generating and dispensing ground coffee) and relative to the brewing unit.

[0093] The working position of the portafilter assembly may lie outside the filling position when it is inserted into the machine unit. Therefore, after insertion, the portafilter assembly must first be pivoted into the filling position and then into the brewing position. The filling and brewing positions are thus defined by the combination of the portafilter assembly's working position and the pivot position of the linear guide.

[0094] When inserting the portafilter unit into the machine unit, the working position can also coincide with the filling position if the portafilter unit is in the appropriate swivel position, so that after filling it with coffee powder, the portafilter unit only needs to be swivelled into the brewing position.

[0095] After positioning the portafilter filled with coffee powder in the brewing position, the brewing process is initiated, according to both versions, by driving the brewing piston parallel to the piston axis into its brewing position towards the coffee receiving chamber by means of the piston drive.

[0096] The piston axis is arranged, in particular, perpendicular to the insertion direction or insertion plane of the portafilter assembly. The piston axis also runs, in particular, perpendicular to the receiving opening of the portafilter assembly.

[0097] The piston of the brewing unit acts as a coffee press or tamper by pressing the coffee grounds into the brewing chamber. The degree of tamping can be determined by adjusting the piston pressure via a control unit.

[0098] The brewing piston remains in its brewing position during the brewing process and, together with the portafilter assembly, forms the (closed) brewing chamber. The brewing piston can be locked in the brewing position by a locking device, in particular a mechanical locking device. The locking device can be actuated, for example, by the piston drive.

[0099] The water pump now pumps water from a water tank into the brewing chamber. The water is heated by a heating unit along the way. The heated brewing water is then forced under pressure into the brewing chamber via a brewing water inlet that runs through the piston.

[0100] The brewed coffee flows down the underside of the portafilter unit through a coffee outlet opening from the portafilter unit, e.g. into a provided drinking vessel.

[0101] At the end of the brewing process, the supply of hot brewing water is stopped and the brewing water pressure in the brewing chamber is released. The brewing chamber is opened by returning the brewing piston to its starting position, and the coffee intake opening is released. The portafilter assembly is then completely pulled out of the machine unit via a linear (counter-)movement along the linear guide.

[0102] The coffee grounds can now be removed from the portafilter, for example by tapping it out. The portafilter can then be prepared for a new brewing process.

[0103] The coffee machine according to the invention is characterized by the following advantages: Easy and quick attachment and removal of the portafilter unit to the machine unit, particularly without significant effort; thanks to the movable brewing piston, which allows for individual coffee tapping even with varying amounts of coffee grounds in the coffee chamber, different sized portafilter inserts are no longer necessary; thanks to the movable brewing piston, tightening the portafilter unit against a (fixed) piston on the machine unit is not required for coffee tapping; individual adjustment of the coffee tapping thanks to the brewing piston, which is driven into the coffee chamber or brewing chamber by means of a piston drive controlled by the control unit; residue-free change of coffee type thanks to the guideless dispensing of coffee grounds from the conical burr grinder into the coffee chamber of the portafilter unit.

[0104] The invention will now be explained in more detail with reference to specific embodiments illustrated in the accompanying figures. These figures schematically depict: Figure 1a: Perspective view of a first embodiment of an arrangement of brewing unit and grinder as well as linear guide device and portafilter assembly of a portafilter machine from a front oblique angle; Figure 1b: Cross-section through the arrangement according to Figure 1a Figure 1c: further perspective view of the arrangement according to Figure 1a Figure 2: Perspective view of the portafilter assembly from a top oblique angle; Figure 3: Perspective view of the linear guide device according to Figure 1awithout portafilter assembly from a bottom angle; Figure 4a: perspective view of a second embodiment of an arrangement of brewing unit and grinder as well as linear guide device and portafilter assembly of a portafilter machine from a bottom angle; Figure 4b: perspective view of the arrangement according to Figure 4a from the front; Figure 4c: further perspective view of the arrangement Figure 4a from the front; Figure 5: schematic view of a screen carrier machine with an arrangement according to Figures 1a to 1c Figure 6: Perspective view of the grinding mechanism according to Figures 1a to 1c from a low angle.

[0105] According to a first embodiment according to Figures 1a to 1cThe coffee machine 1 comprises a brewing unit 10 and a device for producing and dispensing coffee powder 30 with a conical burr grinder 31. A holding and guiding device 40 with a linear guide 41 is arranged below the brewing unit 10 and the device 30. The linear guide 41 comprises two parallel guide rails 42a, 42b spaced apart from each other, each of which has a guide slot 44 for the sliding reception of guide strips 55 on a portafilter device 50.

[0106] Furthermore, the coffee machine 1 comprises a portafilter device 50 with a portafilter housing 54 and a handle body 53 for holding the portafilter device 50. On the outside of the portafilter housing 54, two guide rails 55 are arranged laterally and parallel to each other on both sides of a receiving opening 56 for insertion into the guide slots 44 of the guide rails 42a, 42b.

[0107] The brewing unit 10 and the device 30 with conical grinder 31 are arranged one behind the other along the insertion axis EA, with the device 30 with conical grinder 31 being arranged in the insertion direction ER after the brewing unit 10.

[0108] The portafilter assembly 50 can be inserted into the machine unit 2 of the coffee machine 1 via the guide strips 55, which engage laterally in the guide slots 44 of the guide rails 42a, 42b. The machine unit 2 corresponds to the coffee machine 1 without the portafilter assembly 50.

[0109] The portafilter assembly 50 can be inserted into a filling position FS, in which it is positioned below the unit 30 or the grinder 31. The holding and guiding device 40 forms an end stop 45, which limits the insertion depth and simultaneously ensures the precise positioning of the portafilter assembly 50 in the filling position FS for filling with ground coffee 22. That is, the portafilter assembly 50 enters the filling position FS when it reaches the stop 45.

[0110] The conical burr grinder 31 comprises a multi-part housing 35 in which the grinding cone 32 and the grinding ring 33, which surrounds the grinding cone 32, are arranged. The grinding cone 32 tapers upwards along the cone's axis from its base. The grinding ring 33 is rotatably mounted in the housing 35 around the cone's axis via bearings, such as ball bearings, and is driven by an electric motor 34. The 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's axis. The ground coffee powder exits the grinding gap at the bottom, near the base of the cone, and falls downwards due to gravity.

[0111] The grinding cone 32 is rigidly, i.e., fixed in place, and connected at both its cone ends to the housing 35 via several connecting webs 36a, 36b. The connecting webs 36a, 36b extend radially outwards from the cone axis towards the housing 35 in a star-like pattern.

[0112] At the upper end of the grinding cone, several passage openings are formed between the connecting webs 36a to allow coffee beans to pass downwards in the direction of gravity G into the conical grinding mechanism 31 (see Figure 1c ).

[0113] At the lower end of the grinding cone, i.e. at the base of the cone, several passage openings are formed between the connecting webs 36b for allowing coffee powder 22 to pass from the conical grinder 31 downwards in the direction of gravity G into the coffee receiving chamber 51 of the portafilter device 50 (see Figure 6 ).

[0114] However, it is not essential that the coffee machine contains an integrated grinder as shown in the figures. The grinder can, for example, also be arranged or attached to the coffee machine in such a way that the portafilter is already filled with ground coffee before being inserted into the machine unit. Furthermore, it is also possible that the coffee machine does not contain a grinder and the ground coffee is supplied by a separate coffee grinder or from a storage container.

[0115] The portafilter assembly 50 includes a filter insert 49 recessed into the portafilter housing 54, with a brewing screen 52 forming the base of the filter insert 49. The filter insert 49 forms the coffee receiving chamber 51 for receiving the ground coffee 22. This chamber is open at the top. Accordingly, the filter insert 49 has a receiving opening 56 at the top, opposite the brewing screen 52. The coffee receiving chamber 51 is cylindrical but has a circumferential, funnel-shaped extension 57 in the area of ​​the receiving opening 56. In this embodiment, the filter insert 49 is permanently connected to the portafilter housing 54 and is therefore not removable. However, the filter insert 49 can also be removable. Likewise, the filter insert can be an integral part of the portafilter housing 54.

[0116] Following the filling of the coffee receiving chamber 51 of the portafilter assembly 50 with coffee powder 22, the portafilter assembly 50 is retracted in a linear counter-movement via the linear guide device 41 into the brewing position BS. In the brewing position BS, the portafilter assembly 50 is located below the brewing unit 10.

[0117] As from the Figures 2 and 3As will be shown in more detail, the linear guide device 41 and the portafilter assembly 50 have cooperating locking means 43, 59, which allow for precise, self-centering positioning of the portafilter assembly 50 in the brewing position BS. In the present embodiment, locking notches 43 are formed in the guide slot 44 of the guide rails 42a, 42b, into which spring-loaded balls 59 arranged on the guide rails 55 of the portafilter assembly 50 engage. The locking notches 43 form an entry ramp in the insertion direction ER and in the opposite direction ER. This is intended to reduce the force required to push or pull the portafilter assembly 50 out of the locking position, so that the portafilter assembly 50 can be easily pushed or pulled past the locking position or pulled or pushed out of the locking position.

[0118] The brewing unit 10 comprises a brewing piston 4 with a piston shaft 5, which is guided in a piston shaft housing 7, and a piston plunger 6 located at the lower end, i.e., towards the portafilter assembly 50, which is guided in a piston plunger guide housing 19. The piston plunger guide housing 19 includes a piston shaft guide tube 15, through which the piston shaft 5 is guided from the piston shaft housing 7 into the piston plunger guide housing 19. The piston axis KA is perpendicular to the insertion direction ER or insertion plane EE of the portafilter assembly 50 and also runs perpendicular to the receiving opening 56 of the portafilter assembly 50.

[0119] To initiate the brewing process, the brewing piston 4 is moved downwards from its initial position AK in the direction of gravity G towards the coffee receiving chamber 51 of the portafilter assembly 50 by a piston drive 21. The piston plunger 6 is moved into the coffee receiving chamber 51 and compresses the coffee grounds 22. In other words, the brewing piston 4 performs the so-called "tamping" action. Upon reaching the brewing position BK, the advance of the brewing piston 4 is stopped. The coffee receiving chamber 51, now closed by the piston plunger 6, forms a brewing chamber 3.

[0120] The piston drive 21, and thus also the piston pressure, which in turn is a measure of the coffee treading, is controlled by the control unit 20. The piston drive 21 can be an electric drive or a hydraulic drive. In the latter case, as explained in more detail below, a hydraulic fluid, such as water, is introduced into a pressure chamber 9 via a feed 25. A hydraulic drive of the brewing piston 4 can be, as shown by the Figure 5 As explained further below, this is done via the water pump 62 of the brewing water preparation unit 60.

[0121] The coffee machine or machine unit 2 further includes a brewing water preparation unit 60 with a water tank 61, a water pump 62 and a heating unit 63 for supplying hot brewing water under pressure into the brewing chamber 3 (see also Figure 5). The hot brewing water is fed under pressure into the brewing chamber 3 via a brewing water feed 18 guided by the piston ram 6.

[0122] The portafilter assembly 50 includes a coffee outlet opening 58 located below the brewing sieve 52. Through this opening, the coffee brewed in the brewing chamber 3 and pressed through the brewing sieve 52 flows downwards, e.g. into a drinking vessel (not shown).

[0123] The brewing piston 4 interacts with a return spring 8. In the present embodiment, this spring is a compression spring 8 in the form of a helical spring surrounding the piston shaft 5. The compression spring 8, which is compressed when the brewing piston 4 is advanced towards the portafilter assembly 50, pushes the brewing piston 4 back to its initial position AK after the brewing process is complete and the piston pressure is released. With a piston drive 21, such as an electric drive that actively moves the brewing piston 4 back, return elements such as return springs are not strictly necessary.

[0124] The brewing piston 4 further comprises a piston guide sleeve 24, by means of which the brewing piston 4 is axially guided in the piston shaft housing 7. The piston guide sleeve 24 is arranged in the upper end section of the brewing piston 4 towards the pressure chamber 9.

[0125] According to the present embodiment, the brewing piston 4 is locked in the brewing position BK against an axial direction opposite to the direction of travel of the brewing piston 4 by a locking device 11. The locking mechanism serves, among other things, to relieve the piston drive 21. Thus, the piston pressure exerted on the brewing piston 4 by the piston drive 21 to compress the coffee powder 22 is significantly lower than the brewing water pressure built up in the brewing chamber 3 by the water pump 62 of the brewing water preparation unit 60, which acts as a counter-pressure on the brewing piston 4. Thanks to the locking of the brewing piston 4 during the brewing process, the piston drive 21 does not need to build up a counter-pressure corresponding to the brewing water pressure. However, the locking device 11 is not essential. Locking can also be achieved by the piston drive 21 itself.

[0126] The embodiment according to Figures 1a to 1cshows a special design of a locking device, which is characterized by the fact that it is also triggered via the piston drive 21.

[0127] In this case, the piston drive 21 exerts hydraulic pressure on the brewing piston 4 via a hydraulic pump using hydraulic fluid. For this purpose, hydraulic fluid is introduced into a pressure chamber 9 via a feed 25, similar to the piston water feed. This pressure chamber is limited, among other things, by the movable brewing piston 4. The pressure chamber 9 is designed to withstand pressure from the hydraulic system. Figure 1b not particularly well shown, as it only expands spatially through the movement of the brewing piston 4 from its starting position AK downwards into the brewing position BK.

[0128] As shown by the Figure 5To explain in more detail, the hydraulic pump of the water pump 62 can correspond to the brewing water preparation unit 60, and the hydraulic fluid can be water from the water tank 61 of the brewing water preparation unit 60.

[0129] Due to the pressure of the hydraulic fluid (e.g. water) flowing into the pressure chamber 9, the brewing piston 4 moves against the restoring force of the return spring 8 from its starting position AK downwards towards the portafilter device 50 into the brewing position BK.

[0130] The pressure chamber 9 is bounded at the top by the piston shaft housing 7. The piston shaft housing 7 is axially movable relative to the piston guide housing 19 and, correspondingly, relative to the piston shaft guide tube 15, via two connecting screws 23 along the connecting screws 23. The connecting screws 23 form a guide section, in particular a threadless section, for the axial guidance of the axially movable piston shaft housing 7. The piston shaft housing 7 is held in a starting position by two compression springs 17, which press the piston shaft housing 7 downwards. The compression springs 17 are designed as helical springs and each surrounds the connecting screws 23.

[0131] Upon reaching brewing position BK, the downward axial movement of the brewing piston 4 is complete. The pressure in the pressure chamber 9, which continues to increase, now exerts a corresponding force on the piston shaft housing 7, causing it to move slightly upwards against the restoring force of the pressure springs 17, in a direction opposite to the piston movement.

[0132] The piston shaft housing 7 is also connected to an annular actuating element 12 of the locking device 11, which surrounds the piston shaft guide tube 15 and is also moved upwards accordingly. In its upper section, the actuating element 12 forms a radial gap to the piston shaft guide tube 15, creating an annular cavity or gap. In its lower section, the actuating element 12 is in sliding contact with the piston shaft guide tube 15 and rests against it. The upper and lower sections transition into each other by means of a guide ramp.

[0133] At the level of the actuating element 12, the piston shaft guide tube 15 has radial through-openings 14 in which ball bodies 13 are movably mounted.

[0134] The piston shaft 4 has a plurality of ring-shaped circumferential recesses 16 into which the spherical bodies 13 can engage.

[0135] In the unlocked position, the piston shaft housing 7, and with it the actuating element 12, is held in a lower starting position by the restoring force of the compression springs 17. The upper section of the actuating element 12, with its annular cavity or gap, is located at the level of the radial through-openings 14. The ball bodies 13 are recessed from the radial through-openings 14 and engage in the annular cavity.

[0136] When the brewing piston 4 reaches the brewing position BK, the piston shaft housing 7, together with the actuating element 12, is slightly raised in the axial direction, as mentioned. This causes the lower section of the actuating element 12, along with the annular gap, to move upwards, thereby pushing the ball bodies 13 radially inwards into the through-openings 14 by the downwardly moving lower section. The guide ramp between the upper and lower sections ensures that the ball bodies 13 do not become wedged against the actuating element 12, but rather move evenly into the through-openings 14.

[0137] The spherical bodies 13, which are pushed back into the radial through-openings 14, now engage on the other side in a recess 16 on the piston shaft 5 and cause the brewing piston 4 to be locked in the brewing position BK. The spherical bodies 13 therefore act as locking elements.

[0138] The locking mechanism remains in place as long as the hydraulic pressure in the pressure chamber 9 is able to push the piston shaft housing 7 upwards against the restoring force of the compression springs 17.

[0139] After the brewing process is complete, the pressure in the pressure chamber 9 is released, causing the piston shaft housing 7, together with the actuating element 12, to retract downwards into its initial position due to the restoring force of the compression springs 17. The upper section of the actuating element 12, together with the annular gap between the actuating element 12 and the piston shaft guide tube 15, returns to the level of the radial through-openings 14.

[0140] Furthermore, as the pressure in the pressure chamber 9 decreases, the restoring force exerted by the compression spring 8 on the brewing piston 4 now predominates. The compressive force of the compression spring 8, or rather the upward movement of the brewing piston 4 by the compression spring 8, forces the spherical bodies 13 out of the recess 16 and back into the radial through-openings 14 and the annular gap behind it.

[0141] The locking mechanism is released and the brewing piston 4 moves back upwards to its starting position AK due to the restoring force of the compression spring 8.

[0142] The Figure 5Figure 1 shows a special further development of the coffee machine 1, which is characterized by the fact that the brewing piston 4 is driven into the brewing position BK by the water pump 62 of the brewing water preparation unit 60. The water pump 62 draws the water from a water tank 61 via a supply water line 64. The water pump 62 is connected to the brewing water inlet 18 on the piston ram 6 via a brewing water line 66. A heating unit 63, e.g., a thermoblock or flow heater, is arranged along the brewing water line 66 to heat the brewing water flowing through the brewing water line 66. The water pump 62 pumps water from the water tank 61 under pressure through the brewing water line 66 into the brewing chamber 3. The brewing water is heated by the heating unit 63 on its way through the brewing water line 66.

[0143] A 3 / 2-way valve 72 is arranged on the brewing water line 66, which includes an additional connection for draining residual water into a collection container, such as a drip tray, after the brewing process. The 3 / 2-way valve 72 is switched via the control unit 20.

[0144] The water pump 62 is further connected to a piston water line 65, through which water is supplied from the water tank 61 to a pressure chamber 9 in the piston shaft housing 7 to drive the brewing piston 4 from the starting position AK to the brewing position BK (see Figure 1b ) is pumped.

[0145] The piston water line 65 has a check valve 71, which prevents the backflow of water from the pressure chamber 9 into the water pump 62. Furthermore, a 3 / 2-way valve 70 is arranged in the piston water line 65 between the check valve 71 and the pressure chamber 9. A return water line 67 is connected to the 3 / 2-way valve 70, through which piston water can be directed back into the water tank 61. A pressure gauge 73 for monitoring the pressure in the pressure chamber 9 is also located on the piston water line 65.

[0146] To advance the brewing piston 4 from the starting position AK to 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.

[0147] After the brewing piston 4 has reached its brewing position BK and is locked, the water pump 62 pumps heated water from the water tank 61 through the brewing water line 66 into the brewing chamber 3 and builds up a brewing pressure which is usually higher than the piston pressure.

[0148] 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 unit 20. The check valve 71 in the piston water line 65 prevents a pressure loss in the pressure chamber 9 when the water pump 62 switches from the piston water line 65 to the brewing water line 66.

[0149] At the end of the brewing process, the pressure in the brewing water line 66 is reduced and the 3 / 2 way valve 72 is switched by the control device 20 so that the residual water is drained into a collection container (not shown).

[0150] Furthermore, the pressure is also reduced in the piston water line 65 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 line 67.

[0151] The Figures 4a to 4c Figure 1 shows a second embodiment of a machine unit or a holding and guiding device 140. The holding and guiding device 140 comprises a support plate 143 on which a linear guide device 141 is pivotably arranged via a pivot axis S.

[0152] The linear guide device 141 also includes two guide rails 142a, 142b arranged at a distance from each other and running parallel to each other, each of which has a guide slot 144 for the sliding reception of guide strips 55 of a portafilter device 50. The portafilter device 50 corresponds to the portafilter device 50 according to the first embodiment according to the Figures 1a to 1c , 2 and 3 .

[0153] Likewise, the device for producing and dispensing coffee powder 30 and the brewing unit 10 correspond in particular to those of the first embodiment according to the Figures 1a to 1c .

[0154] In the second embodiment, however, the device 30 and the brewing unit 10, and correspondingly also the filling position FS and the brewing position BS of the portafilter device 50, are not arranged one behind the other in the insertion direction ER. Instead, the device 30 and the brewing unit 10, and correspondingly the filling position FS and the brewing position BS, are arranged along a (geometric) circle whose center is formed by the pivot axis S.

[0155] The portafilter assembly 50 can now be inserted into the linear guide device 141 in a linear motion into a working position. The working position can be defined by an insertion limit, such as a stop. The working position is located on the same circular path as the filling position FS and the brewing position BS. By pivoting the portafilter assembly 50 in the pivot direction SR about the pivot axis S, the portafilter assembly 50 can now be alternately pivoted into the filling position FS and the brewing position BS.

[0156] Since this embodiment only has one insertion position, namely the working position, it can be defined by a stop. Locking devices, such as those provided in the first embodiment with two insertion positions arranged one behind the other, are not necessary here.

Claims

1. A coffee machine (1), comprising a machine unit (2) and a portafilter device (50) with a coffee receiving space (51) and a brewing filter (52), said portafilter device (50) being removable from the machine unit (2), wherein the machine unit (2) comprises a movably mounted brewing piston (4), a brewing water preparation device (60) for producing and delivering hot water under pressure into the coffee receiving space (51) of the portafilter device (50), and a holding and guiding device (40) for receiving and holding the portafilter device (50) on the machine unit (2), and the holding and guiding device (40) comprises a linear guide device (41) for the linear insertion of the portafilter device (50) into the machine unit (2), and the portafilter device (50) which is held in the linear guide device (41) is movable in the machine unit (2) into a brewing position (BS) for brewing a coffee, characterised in that, the machine unit (2) comprises a device (30) for delivering coffee powder into the coffee receiving space (51) of the portafilter device (50), and the portafilter device (50) which is held in the linear guide device (41) is movable in the machine unit (2) into a filling position (FS) for delivering coffee powder into the coffee receiving space (51) of the portafilter device (50) which is different from the brewing position (BS).

2. A coffee machine (1) according to claim 1, characterised in that the linear guide device (41) comprises two guide contours which run in parallel and are distanced to one another and the coffee receiving space (51) is arranged in a portafilter housing (54) of the portafilter device (50), and guide bodies (55) which interacting with the linear guide device (41) form a linear guide are arranged laterally on the portafilter housing (54).

3. A coffee machine (1) according to one of the claims 1 to 2, characterised in that the portafilter device (50) can be pushed into the brewing position (BS) in a linear movement via the linear guide device (41).

4. A coffee machine (1) according to one of the claims 1 to 3, characterised in that the device (30) for delivering coffee powder is a device for producing and delivering coffee powder into the coffee receiving space (51) of the portafilter device (50).

5. A coffee machine (1) according to one of the claims 1 to 4, characterised in that the portafilter device (50) can be pushed into the filling position (FS) in a linear movement via the linear guide device (41), in which filling position the coffee receiving space (51) of the portafilter device (50) can be filled with coffee powder.

6. A coffee machine (1) according to one of the claims 1 to 5, characterised in that the portafilter device (50) which is held in the linear guide device (41) is movable in the machine unit (2) between the filling position (FS) and the brewing position (BS).

7. A coffee machine (1) according to one of the claims 1 to 6, characterised in that the portafilter device (50) is movable in the machine unit in a plane, in particular in a horizontal plane, between the filling position (FS) and the brewing position (BS).

8. A coffee machine (1) according to one of the claims 1 to 7, characterised in that the movement between the filling position (FS) and the brewing position (BS) is a linear movement or a pivoting movement.

9. A coffee machine (1) according to one of the claims 1 to 8, characterised in that the brewing position (BS) and the filling position (FS) are arranged behind one another along an insertion axis (EA).

10. A coffee machine (1) according to claim 9, characterised in that the filling position (FS) is arranged after the brewing position (BS) in the insertion direction (ER).

11. A coffee machine (1) according to one of the claims 1 to 10, characterised in that the linear guide device (41) is pivotably mounted on the machine unit (2) via a pivot axis (S) which is arranged perpendicularly to the insertion plane (EE) and the portafilter device (50) which is pushed into the machine unit (2) via the linear guide device (41) is pivotably mounted together with the linear guide device (41) between a filling position (FS) and the brewing position (BS).

12. A coffee machine according to one of the claims 4 to 11, characterised in that the device for producing and delivering coffee powder (50) comprises a cone grinder (31) with an inner-lying, stationary grinding cone (32) and with an outer-lying, driven grinding ring (33) which surrounds the grinding cone (32), wherein the cone grinder (31) is designed and arranged in the machine unit (2) such that the ground coffee powder falls downwards out of the cone grinder (31) without guidance by way of gravitational force (G) into the coffee receiving space (51) arranged below, of the portafilter device (50) which is positioned in the filling position (FS).

13. A method for brewing a coffee with a coffee machine (1) according to one of the claims 1 to 12, characterised in that for brewing a coffee, the portafilter device (50) is pushed into the machine unit (2) by way of a linear movement via the linear guide (42a, 42b, 55) and after completion of the brewing procedure is pulled out of the machine unit (2) again in a linear counter-movement.

14. A method according to claim 13, characterised in that for brewing a coffee, the portafilter device (50) is firstly pushed into a filling position (FS) in a linear movement via the linear guide (42a, 42b, 55) and after the filling of the coffee receiving space (51) with coffee powder is retracted into a brewing position (BS) in a linear counter-movement.

15. A method according to one of the claims 13 to 14, characterised in that for brewing coffee, the portafilter device (50) is pushed into the machine unit (2) in a linear movement via the linear guide (42a, 42b, 55) and for filling the coffee receiving space (51) with coffee powder and for brewing the coffee is pivoted together with the holding and guiding device (40) between a filling position (FS) and a brewing position (BS).