Brewing unit of a coffee machine

Abstract

A brewing unit (1) of a piston-driven coffee machine, wherein the brewing unit (1) is designed in the form of a spindle brewing unit with a brewing-unit slider (2) as a brewing chamber, two piston units as dispersion screen (9) and tamper (10), and also a drive motor and at least one gear mechanism, wherein the brewing unit (1) has a double-spindle arrangement comprising an outer spindle (3) and an inner spindle (7), wherein the outer spindle (3) is coupled to the inner spindle (7) via the at least one gear mechanism, wherein the brewing-unit slider (2) can be displaced from a first end position into an intermediate position, then into a second end position and back again into the first end position, wherein the outer spindle (3) has a movement thread (3d), which engages with an outer-spindle nut (13) arranged in the brewing-unit slider (2). In the first end position of the brewing-unit slider (2), the movement thread (3d) of the outer spindle (3) is not in engagement with the outer-spindle nut (13), wherein a speed of the brewing-unit slider (2) is zero even if the outer spindle (3) continues rotating, wherein the brewing-unit slider (2) is fixed in the first end position by means of a retaining device (HR), and wherein, in the second end position of the brewing-unit slider (2), the movement thread (3d) of the outer spindle (3) remains in engagement with the outer-spindle nut (13) and the drive motor has been switched off. A piston coffee machine is equipped with such a brewing unit (1).

Description

[0001] Brewing unit of a coffee machine

[0002] The invention relates to a brewing unit of a piston coffee machine according to the preamble of claim 1 and to a piston coffee machine with such a brewing unit.

[0003] Brewing units for piston coffee machines come in many different designs. Within the brewing unit of a piston coffee machine, coffee powder is ground into a brewing chamber and then pressed into a coffee cake. Heated water is then passed through the cake under pressure to extract flavors from the grounds. After a product-specific amount of water has passed through, the moistened coffee powder is pressed out, and the coffee cake (grounds) is deposited into the grounds container.

[0004] There are different drive concepts to achieve the necessary relative positions of the plunger, douchette and brewing chamber.

[0005] Document EP 2 907 427 B1 describes a non-linear gear section that achieves a compromise between high pressing forces and simultaneously short travel cycles. To reach the various positions, the functional elements are moved at large inclines. When compacting the coffee powder, the drive motor is geared down at a significantly smaller incline in order to transmit large forces with the same guide.

[0006] Document DE 10 2019 119 103 A1 relates to a brewing unit of a piston coffee machine. The brewing unit is designed as a spindle brewing unit with a brewing carriage as the brewing chamber, two piston units as a douchette and plunger, a drive motor, and at least one gear. The brewing unit has a double spindle arrangement with an outer spindle and an inner spindle. The brewing carriage is adjustable from a first end position to an intermediate position, then to a second end position, and back to the first end position. The outer spindle has a movement thread that engages with an outer spindle nut axially fixed in the brewing carriage. The movement thread of the outer spindle is disengaged from the outer spindle nut in the first end position and in the second end position of the brewing carriage, and the speed of the brewing carriage is zero, even if the outer spindle continues to rotate.A piston coffee machine is specified. These designs have proven successful, but there is a constant need for improvements in the pursuit of cost savings in components, functional assemblies, assembly times, and maintenance.

[0007] The invention therefore has the object of advantageously further developing a brewing unit of a piston coffee machine in order to create an improved brewing unit and an improved piston coffee machine.

[0008] The invention solves this problem by a brewing unit having the feature of claim 1 and by a piston coffee machine having the feature of claim 10.

[0009] A brewing unit of a piston coffee machine according to the invention, wherein the brewing unit is designed as a spindle brewing unit with a brewing carriage as the brewing chamber, two piston units as a douchette and plunger, a drive motor, and at least one gear, wherein the brewing unit has a double spindle arrangement with an outer spindle and an inner spindle, wherein the outer spindle is coupled to the inner spindle via the at least one gear, wherein the brewing carriage is adjustable from a first end position to an intermediate position, then to a second end position, and back to the first end position, wherein the outer spindle has a movement thread which engages with an outer spindle nut arranged in the brewing carriage, is characterized in that the movement thread of the outer spindle is disengaged from the outer spindle nut in the first end position of the brewing carriage,wherein a speed of the brewing carriage is zero, even if the outer spindle continues to rotate, wherein the brewing carriage is fixed in the first end position by means of a holding device, and that the movement thread of the outer spindle remains in engagement with the outer spindle nut in the second end position of the brewing carriage and the drive motor is switched off.

[0010] One advantage of this is that it allows the brewing carriage to be easily left at rest in its respective end position, while the outer spindle, driven by the drive motor, continues to drive the inner spindle via the gear box to position the inner spindle and thus the shower head. An additional motor is not required.

[0011] A piston coffee machine according to the invention has the brewing unit described above, with the advantage of a compact design. In one embodiment, the brewing carriage has a first feed gear with the outer spindle nut and the holding device. This results in an advantageously simple and compact design.

[0012] In a further embodiment, it is provided that the outer spindle nut is arranged with axial play in a receptacle of the brewing carriage, wherein a first end Z contact side (13d) of the outer spindle nut is in contact with a first pressure side of the receptacle in the first end position, wherein a second end Z contact side of the outer spindle nut and a second pressure side of the receptacle are spaced apart by the play, and wherein the second end Z contact side of the outer spindle nut and the second pressure side of the receptacle are in contact and the play is arranged between the first end Z contact side of the outer spindle nut and the first pressure side of the receptacle when the movement thread of the outer spindle and the outer spindle nut are engaged. An advantage of this embodiment is that a so-called "spindle-in process" is improved, since in this way a load-free spindle-in of the brewing carriage takes place.

[0013] Yet another embodiment provides that at least one contact side of the threaded region of the internal thread of the outer spindle nut is segmented with segments. The segments are arranged spaced apart from one another around the internal thread on the circumference of the at least one contact side of the outer spindle nut, each having a resilient effect, and protruding from the respective contact side of the outer spindle nut. In this way, jamming between the outer spindle nut and the movement thread of the outer spindle is advantageously avoided during the threading process.

[0014] In another embodiment, the inner spindle is connected to the adjustable douchette or the adjustable plunger and coupled to the drive via a second feed gear, and the plunger or douchette is arranged in a stationary manner. The adjustable brewing carriage is guided for longitudinal displacement by means of the outer spindle and at least one guide rod. The douchette or the plunger is guided for longitudinal displacement within the brewing carriage. The brewing carriage and the douchette or the plunger are adjustable at different speeds in common directions of movement. This results in an advantageously simple and cost-effective design. Furthermore, very high adjustment speeds are advantageously achievable.In a further embodiment, the douchette is coupled to the brewing carriage by means of an activated, controllable driver device when a coupling between the outer spindle and the brewing carriage is released via the first feed gear and in the area of ​​reversal play of the outer spindle nut with respect to the brewing carriage, in order to transfer the movement of the douchette to the brewing carriage. This enables an advantageously simple coupling.

[0015] It is also advantageous if the controllable driver device is designed as a controllable tappet device, since this enables a compact design.

[0016] A further embodiment provides for the controllable ram device to have a hydraulic, pneumatic, or mechanical ram drive. This provides an advantageously simple drive option.

[0017] In yet another embodiment, the plunger drive is connected to a hydraulically, pneumatically, or mechanically activated douchette seal. This allows for an advantageously simple control of the plunger drive.

[0018] In one embodiment, the holding device comprises a permanent magnet, an electrically controllable electromagnet, or a mechanical locking mechanism. Permanent magnets and electromagnets are advantageously cost-effective, high-quality components, while a mechanical locking mechanism offers the advantage of a simple design without the need for electrical installations.

[0019] The invention is described in more detail below using an exemplary embodiment and a variant with reference to the drawings. The figures serve only to explain the invention in more detail and are not limiting. Individual features described can also be applied to further embodiments within the scope of general technical knowledge. They show:

[0020] Figure 1: a schematic perspective view of an embodiment of a brewing unit of a coffee machine according to the invention in a first position;

[0021] Figures 2-3: various schematic views of the brewing unit according to Figure 1 in the first position; Figures 4-6: various schematic views of the brewing unit according to Figure 1 in a second position;

[0022] Figures 7-9: various schematic views of the brewing unit according to Figure 1 in a third position;

[0023] Figures 10-11: various schematic views of the brewing unit according to Figure 1 in a carrying position;

[0024] Figures 12-14: various schematic views of the brewing unit according to Figure 1 in a fourth position;

[0025] Figures 15-16: various schematic views of the brewing unit according to Figure 1 in a final position;

[0026] Figure 17: a schematic sectional view along line XVII in Figure 2;

[0027] Figure 18: a schematic, enlarged sectional view of a tappet device;

[0028] Figure 19-20: schematic sectional views of an external spindle nut;

[0029] Figure 21 is a schematic view of a drive side of the brewing unit according to Figure 1;

[0030] Figures 22-24 are schematic sectional views along line XXII-XXIII-XXIV in Figure 21;

[0031] Figures 25-27 schematic views of a variant of the outer spindle nut;

[0032] Figure 28 is a schematic side view of the brewing unit with the variant of the external spindle nut according to Figures 25-27; and

[0033] Figure 29 is a schematic sectional view of the outer spindle nut variant in the installed state.

[0034] Coordinates x, y, and z are indicated in the figures for orientation purposes. Fig. 1 shows a schematic perspective view of an embodiment of a brewing unit 1 according to the invention for a piston coffee machine. Fig. 2 shows a schematic plan view of the top of the brewing unit 1 in an x-y plane according to Fig. 1. A schematic longitudinal sectional view of the brewing unit 1 according to Figs. 1-2 in an xz plane is shown in Fig. 3.

[0035] The example shown here is a horizontal brewing unit 1. This design can also be applied to a vertical brewing unit 1 or one with any other inclination angle. Brewing unit 1 is a spindle brewing unit.

[0036] The brewing unit 1 here comprises a brewing carriage 2, which is also referred to as a brewing chamber, an outer spindle 3, at least one guide rod 4 (in the example shown there are two guide rods 4), a first base plate, which is referred to here as drive plate 5, and a second base plate, which is referred to here as plunger plate 6, an inner spindle 7, two piston units, namely a so-called douchette 9 and a plunger 10, and at least one drive motor, not shown.

[0037] The system offers the possibility of realizing the required relative positions between the plunger 10, the douchette 9 and the brewing carriage 2 of the brewing unit 1 for a piston coffee machine (not shown) by means of a double spindle arrangement and a drive.

[0038] The drive motor creates a relative movement between the plunger 10 and the douchette 9 in the x-direction, allowing the distance between them to be adjusted. Defined pressing forces can then be set using various motor torques. At the same time, the brewing carriage 2 moves. This makes it possible to create a filling position for the coffee powder, create a sealed brewing chamber, and finally eject the pressed coffee cake.

[0039] Here, the douchette 9 and the brewing carriage 2 are moved into different positions in the x-direction, whereby the stamp 10 is fixedly attached to the stamp plate 6.

[0040] The double spindle arrangement comprises the outer spindle 3 and the inner spindle 7. The outer spindle 3 adjusts the brewing carriage 2, the inner spindle 7 adjusts the shower 9.

[0041] The outer spindle 3 is coupled to the brewing carriage 2 via a first feed gear 12. This will be described in detail below.

[0042] In addition, the brewing carriage 2 is driven by the douchette 9 by means of a driver device to overcome so-called backlash. The controllable driver device is designed as a controllable tappet device 22 and is explained in more detail below.

[0043] Within this reversal play, which has a specific dimension in the x-direction (see play 32 in Fig. 24), the brewing carriage 2 is disengaged from the outer spindle. In this case, a coupling between the outer spindle 3 and the brewing carriage 2 is canceled by the first feed gear 12. When this coupling is canceled in the first end position and in the range of the reversal play, the brewing carriage 2 is coupled to the douchette 9 via the tappet device 22 in order to transmit the movement of the douchette 9 to the brewing carriage 2 when there is no coupling between the outer spindle 3 and the brewing carriage 2. This will be explained further below.

[0044] The brewing carriage 2 is moved from a parking position, which is the first end position of the brewing carriage 2, to an intermediate position, then to a second end position, and back to the first end position. In doing so, the douchette 9 is moved into different positions relative to the brewing carriage 2 and the plunger 10.

[0045] The parking position of the brewing carriage 2 is shown in Fig. 1-3.

[0046] The intermediate position of the brewing carriage 2 is also called the grounds discharge position and is shown in Fig. 12-14.

[0047] Finally, Fig. 15 and 16 show the second end position of the brewing carriage 2.

[0048] The douchette 9 is always arranged in the brewing carriage 2 within a brewing cylinder 20 of the brewing carriage 2 and can assume different relative positions to the brewing carriage 2. These relative positions are made possible independently of one another by the movements of the douchette 9 due to the inner spindle 7 and by the movements of the brewing carriage 2, which is adjustable by the outer spindle 3.

[0049] The plunger 10 can be located outside or inside the brewing carriage 2. Since the plunger 10 is fixed in position here, the relative positions / movements of the brewing carriage 2 and the douchette 9 to the plunger 10 are enabled by the inner spindle 7 (douchette 9) and the outer spindle 3 (brewing carriage 2). It is also conceivable that the plunger 10 could be adjustable.

[0050] The douchette 9 (or the plunger 10) and the brewing carriage 2 always have a common direction of travel, but have different speeds (differential speeds) in order to achieve the necessary relative positions between these two components.

[0051] An exception, however, is the parked position of the brewing carriage 2 (Figs. 1-9). In the parked position, the brewing carriage 2 is fixed to the plunger plate 6 by a holding device HR (see Figs. 19 and 22) and is disengaged from the outer spindle. This allows independent adjustment of the douchette 9 relative to the brewing carriage 2.

[0052] To facilitate the representation of these directions of travel, each figure shows a double arrow indicating the direction of movement BR with two directions of movement BR1 and BR2 running in opposite directions along the x-axis.

[0053] In this way, the brewing unit 1 can be adjusted to the following positions.

[0054] Fig. 1 -3 show a closed position (first position).

[0055] A filling position (second position) is shown in Fig. 4-6.

[0056] Fig. 7-9 show a brewing position (third position).

[0057] A driving position is shown in Fig. 10-11.

[0058] A set drop position (fourth position), also called open position, is shown in Fig. 12-14.

[0059] Fig. 15 and 16 show an end position.

[0060] These positions are explained in more detail below.

[0061] The outer spindle 3 with an outer spindle axis 3a, the guide rods 4 with guide axes 4a, and the inner spindle 7 with an inner spindle axis 7a are arranged parallel to each other. The directions of movement BR1 and BR2 run parallel to these axes 3a, 4a, and 7a.

[0062] The drive plate 5 and the stamp plate 6 of the brewing unit 1 here have rectangular plates which are arranged parallel to each other and at right angles to the axes 3a, 4a, 7a.

[0063] Attached to the drive plate 5 located on the left in Fig. 1, another plate 8 is parallel to the drive plate 5. This plate forms a mount for a drive motor (not shown), which is only indicated by a reference numeral "drive" 14, and a gear (e.g., toothed belt and / or gears). The gear (not shown) couples the rotary movements of the inner spindle 7 and the outer spindle 3. The plate 8 is shown in Fig. 21 and forms a mount for a housing 15a of a second feed gear 15 and for media connections (not described in detail).

[0064] The outer spindle 3 is mounted with a drive end 3b on the drive plate 5. The other end of the outer spindle is mounted as a bearing end 3c on the stamp plate 6. The outer spindle 3 has an external thread as a movement thread 3d, which interacts with the first feed gear 12 of the brewing carriage 2.

[0065] The plunger 10 is attached to the plunger plate 6. The plunger 10, the douchette 9, the brewing carriage 2, and the inner spindle 7 are arranged coaxially with a brewing carriage axis 2a. Here, the brewing carriage axis 2a runs along the inner spindle axis 7a.

[0066] The outer spindle 3 and the guide rods 4 connect the drive plate 5 and the punch plate 6. The guide rods 4 are each covered outwardly over their entire length by a side wall 11, 11a. The respective side wall 11 is connected or integrally connected at the bottom to a respective lower side wall 11a. The lower side walls 11a are folded inward relative to the respective upper side wall 11.

[0067] Fig. 17 shows a schematic sectional view along line XVII in Fig. 2.

[0068] The inner spindle 7 engages with a second feed gear 15. The second feed gear 15 comprises the housing 15a, a cover 16 with an elongated hole 16a (see Fig. 17), an inner spindle nut 17 with an internal thread 17b, and bearings 18, 18a, 18b.

[0069] The housing 15a is attached at one end to the drive plate 5 via the plate 8. The other end of the housing 15a is closed with the cover 16. The inner spindle nut 17 is mounted within the housing 15a with the bearings 18, 18a, and 18b. The bearing 18 is an axial bearing and is supported on a collar 17a of the inner spindle 17. The bearings 18a and 18b are designed as radial bearings and deep groove ball bearings, respectively.

[0070] The collar 17a of the inner spindle nut 17 is located at one end of the inner spindle nut 17 near the cover 16 and points towards the punch plate 6. The other end of the inner spindle nut 17 extends through the drive plate 5 to the plate 8 and interacts with the outer spindle 3 via the gear.

[0071] The inner spindle nut 17 has a through-bore 17c, which is formed in the part facing the cover 16 with an internal thread 17b, which engages with a spindle end 7c of an external thread (movement thread 7b) of the inner spindle 7. The internal thread 17b of the inner spindle nut 17 and the external thread (movement thread 7b) of the inner spindle 7 correspond to each other.

[0072] The inner spindle 7 is also provided with a flattened portion 7e on both sides (best seen in Fig. 17), which, together with the elongated hole 16a of the cover 16 (see Fig. 17), forms a rotation lock for the inner spindle 7. In this way, the inner spindle 7 is arranged in a rotation-proof manner. The inner spindle nut 17 can be rotated about the inner spindle axis 7a by means of the drive 14 and, via the movement thread 7b / 17b, causes a linear movement of the fixed inner spindle 7 and thus of the shower head 9.

[0073] The flat 7e can, for example, be applied directly to the external thread 7b of the internal spindle 7 in such a way that the feed and anti-rotation functions are geometrically connected in parallel. Alternatively, the external thread (movement thread 7b) and the flat 7e can be arranged one behind the other. This avoids modifying the external thread (movement thread 7b), but extends the shape of the internal spindle 7 by the maximum stroke of the douchette 9. The internal spindle 7 comprises the internal spindle axis 7a, the movement thread 7b, the first spindle end 7c, a second spindle end 7d, and the flats 7e. Furthermore, the internal spindle 7 has a thread runout 7f of the movement thread 7b, which points toward the punch plate 6 and is adjacent to a collar 7g. The collar 7g forms a stop in cooperation with the cover 16 and thus an end position of the shower 9 in the direction of movement BR1 in the direction of the drive plate 5 (see Fig. 6).The spindle end 7c extends through the part of the through hole 17c without internal thread 17b outwards through the drive plate 5 and an opening of the plate 8 (Fig. 6).

[0074] The brewing carriage 2 has a substantially hollow-cylindrical housing with a circular cross-section and the brewing carriage axis 2a. A brewing cylinder 19 with a brewing chamber 25, which also has a circular cross-section, is arranged coaxially with the brewing carriage axis 2a in the housing.

[0075] The brewing cylinder 19 has a first end face 19a facing the plunger plate 6. Opposite, the brewing cylinder 19 is provided with a second end face 19b facing the drive plate 5.

[0076] An opening 19c is formed in the brewing cylinder 19's peripheral wall, which communicates with a filling opening 2c of the housing of the brewing carriage 2. In the area of ​​the first end face 19a of the brewing cylinder 19, a seal 19d is arranged circumferentially in an end region of the housing of the brewing carriage 2, which seals the brewing cylinder 19 from the housing of the brewing carriage 2.

[0077] The brewing chamber 25 of the brewing cylinder 19 of the brewing carriage 2 takes the Douchette

[0078] 9 and the plunger 10 in specific positions of the brewing unit 1, which are described in detail below. The douchette 9 and the plunger 10 are guided displaceably relative to the brewing cylinder 19 in the brewing chamber 19 in the directions of movement BR1 and BR2. When the douchette 9 and the plunger

[0079] 10 are both located in certain positions of the brewing unit 1 in the brewing chamber 25, they are opposite each other at different distances.

[0080] The brewing carriage 2 interacts with the plunger 10 in such a way that the brewing cylinder 19 of the brewing carriage 2, with the opening belonging to its first end face 19a, is moved over the plunger 10, whereby the brewing chamber 19 is then sealed on its side facing the plunger plate 6 with a plunger seal 10a. The plunger seal 10a is an adjustable seal, e.g., a hydraulically activated and deactivated seal.

[0081] The brewing carriage 2 is guided via the guide rod 4 between the drive plate 5 and the stamp plate 6 in both directions of movement BR1 and BR2.

[0082] The outer spindle 3 extends through the first feed gear 12. The feed gear 12 is arranged in a receptacle 2c on an outer side of the brewing carriage 2 and has an outer spindle nut 13 (Fig. 19). The outer spindle nut 13 is provided with an internal thread 13b, which corresponds to the external thread (movement thread 3d) of the outer spindle 3.

[0083] The movement thread 3d of the outer spindle 3 engages with the inner thread 13b of the outer spindle nut 13, whereby the movement thread 3d, however, disengages from the outer spindle nut 13 in the rest position (Fig. 1-11) of the brewing carriage 2. This will be explained in detail below in connection with Fig. 19 and 22-24.

[0084] The movement mechanism of the brewing unit 1 is based on two threaded spindle drives, namely the outer spindle 3 and the inner spindle 7. The movement thread 3d of the outer spindle 3 and the movement thread 7b of the inner spindle 7 have different thread pitches.

[0085] The outer spindle 3 is synchronized with the inner spindle 7 via the gear between the drive plate 5 and the plate 8.

[0086] The transmission here is designed as a traction drive with a toothed belt (see Fig. 21). It is also possible for the transmission to be constructed with gears or in combination with a toothed belt. The transmission could also be multi-stage.

[0087] The outer spindle 3 is, for example, the drive shaft of the brewing unit 1 and ensures a linear movement of the brewing carriage 2 via the outer spindle nut 13 mounted on the brewing carriage 2 in its receptacle 2c in a rotationally secured manner.

[0088] The coupling via the gear simultaneously ensures a rotary movement of the inner spindle nut 17, which engages with the movement thread 7b of the inner spindle 7. This results in a linear movement of the douchette 9, which is attached to the second spindle end 7d of the inner spindle 7. An anti-twist device of the inner spindle 7 via the flats 7e in cooperation with the elongated hole 16a in the cover 16 ensures that the douchette 9 and the inner spindle 7 are not rotated about their own axis (inner spindle axis 7a), but only move axially in the movement directions BR1, BR2.

[0089] The movement thread 7b of the inner spindle 7 has a smaller pitch than the movement thread 3d of the outer spindle 3. For this reason, the movement speed of the brewing carriage 2 is many times greater than that of the shower head 9 with the inner spindle 7. Advantageously, the pitch of the inner spindle 7 is selected so that it acts self-locking during the brewing process.

[0090] The douchette 9 and the plunger 10 are arranged in the brewing unit 1 so that their front sides face each other.

[0091] The douchette 9 is firmly connected to the inner spindle 7 and has an adjustable douchette seal 9a running around its outer surface. The douchette seal 9a is an adjustable seal, e.g., a hydraulically activated and deactivated seal.

[0092] The douchette 9 and the douchette sleeve 20 are movable in the directions BR1 and BR2 within the brewing chamber 25 and into the brewing chamber 25 of the brewing cylinder 19 by means of the inner spindle 7. The douchette 9 is inserted into the brewing cylinder 19 through the opening of the brewing cylinder 19 belonging to the second end face 19b.

[0093] In addition, a douchette sleeve 20 with a base 20a is attached to the side of the douchette 9 facing the drive plate 5. The douchette sleeve 20 extends with an interior space 21 over a portion of the inner spindle 7 toward the drive plate 5. An end portion 20b of the douchette sleeve 20 has an opening to the interior space 21, the inner diameter of which corresponds to an outer diameter of the housing 15a of the second feed gear 15.

[0094] On the outside of the shower sleeve 20, the tappet device 22 is arranged, which has a tappet 23. The tappet 23 is adjustable in the radial direction from a first position to a second position and back by means of a tappet drive 24. The tappet drive 24 is designed such that the tappet 23 communicates with the hydraulic seal 9a of the shower via hydraulic lines 24a, 24c (see Fig. 6). A first line 24a is connected to the tappet device 22 and is arranged, here: molded, in a line section 20c of the base 20a of the shower sleeve 20. The first line 24a is connected to the second line 24c in the body of the shower 9 via a line connector 24b. The line connector 24b is sealed via seals 24d to both the bottom 20a of the shower sleeve 20 and the body of the shower 9. The second line 24c communicates with the hydraulic shower seal 9a.

[0095] In its first position, an upper edge of the plunger 23 is below the outside of the shower sleeve 20 or flush with it (Fig. 6).

[0096] When the shower seal 9a is activated, e.g. by an increase in pressure of a hydraulic medium (it can also be compressed air), the plunger 23 is moved radially outwards from its first position (see Fig. 6, 9, 14, 16) to its second position (see Fig. 3 and 11) and protrudes from the outside of the shower sleeve 20.

[0097] In its second position, the plunger 23 protrudes into the opening 19c of the brewing cylinder 19. In this way, a movement of the shower head 9 can be transmitted to the brewing cylinder 19 by means of the inner spindle 7 when the outer spindle nut 13 is disengaged from the movement thread 3d of the outer spindle 3.

[0098] This is the case when the outer spindle nut 13 of the brewing cylinder 19 disengages from the movement thread of the outer spindle 3 during its movement in the direction of movement BR2 towards the plunger plate 6. The plunger 23 of the plunger device 22 is then activated together with the seal 9a of the douchette 9, projects into the opening 19c of the brewing cylinder 19, comes into abutment with a wall of the opening 19c facing the plunger plate 6, and transmits the movement of the douchette 9 to the brewing cylinder 2 until the latter, or the first end face 9a of the brewing cylinder 19, is in its rest position above the plunger 10, wherein an element of the holding device HR comes to abutment against an inner side 6a of the plunger plate 6 (see Figs. 19 and 22).

[0099] Fig. 18 shows a schematic, enlarged sectional view of the tappet device 22.

[0100] The tappet device 22 comprises the tappet 23 with the tappet drive 24, a tappet holder 26, and seals 27, 27a. The tappet 23 is a cylindrical component with a tappet axis 23, a tappet body 23b, an intermediate section 23c, and two collars 23d, 23e. The tappet body 23b is provided with a conical chamfer at its upper end and connected at its lower end via the first collar 23d to the intermediate section 23c, the free end of which terminates in the second collar 23e. An outer diameter of the tappet body 23b is slightly larger than an outer diameter of the intermediate section 23c. The outer diameters of the collars 23d, 23e are the same size and larger than the outer diameter of the tappet body 23b.

[0101] The plunger holder 26 is circularly cylindrical and provided with a circumferential collar 26a at its upper end. A through-opening 26b is formed centrally in the collar 26a, the inner diameter of which corresponds to the outer diameter of the plunger body 23b. Adjoining the collar 26a at the bottom is a hollow-cylindrical guide body 26c with a fastening section 26d and an interior space 26e. The interior space 26e is circularly cylindrical. Its inner diameter corresponds to the outer diameter of the collars 23c, 23d of the plunger 23. The interior space 26e is open at the bottom.

[0102] The plunger 23 is inserted into the plunger holder 26 such that the plunger body 23b extends outward through the through-opening 26b and the collars 23d, 23e are arranged in the interior space 26e. The plunger 23 is slidably guided in the plunger holder 26. The plunger 23 and the plunger holder 26 are arranged coaxially with the plunger axis 23a.

[0103] The seal 27a, e.g. an O-ring, is arranged between the collars 23d and 23e and seals the tappet 23 against an inner wall of the interior space 26e of the tappet holder 26.

[0104] The tappet holder 26 with the tappet 23 is arranged in a receptacle 20e of the Duchette sleeve 20 with the collar 26a of the tappet holder 26. The seal 27, e.g., an O-ring, is located between an underside of the collar 26a of the tappet holder 26 and a shoulder of the receptacle 20. The tappet holder 26 is screwed here with its fastening section 26d, e.g., with an external thread, into a corresponding internal thread of the receptacle 20.

[0105] The receptacle 20 is connected on its underside to the first line 24a of the plunger drive 24, wherein the interior space 26e communicates with the first line 24 of the plunger drive 24. In Fig. 18, the plunger 23 is shown in its second position protruding into the opening 19c of the brewing cylinder 19. In this second position of the plunger 23, the plunger drive 24 is pressurized with hydraulic medium and exerts an upward force (here in the z-direction) on the lower collar 23e of the plunger 23. This force pushes the plunger 23 upward and the upper collar 23d of the plunger 23 against the underside of the collar 26a of the plunger holder 26. The second position of the plunger 23 is thus limited.

[0106] Fig. 18 shows the upper end of the plunger 23 in contact with a chamfer of the opening 19c of the brewing cylinder 19. The chamfer has the task of pushing the plunger 23 back into its first position in the plunger holder 26 when the douchette 9 with the douchette sleeve 20 moves in the x-direction towards the drive side. In doing so, the plunger drive 24 is depressurized. This is necessary when the brewing carriage 2 is moved from its rest position, when the outer spindle nut 13 of the brewing carriage 2 re-engages with the movement thread 3d of the outer spindle 3. The reason for this is that the movement thread 3d of the outer spindle 3 and the movement thread 7b of the inner spindle 7 have different pitches, as already stated above.

[0107] Alternatively, a permanent spring-loaded piston 23 is conceivable, which leads to the forced movement of the brewing carriage 2 (spindle movement). In principle, there would be three operating states:

[0108] 1 ) Tappet 23 engaged (forced drive)

[0109] 2) Tappet 23 compressed (sliding friction within the brewing cylinder 19)

[0110] 3) Tappet 23 not engaged (e.g. during pressing and brewing processes)

[0111] Examples of spring action can be a compression spring or contours integrated directly into the injection molding of a cleaning reservoir, which provide a suitable spring force.

[0112] In a further alternative, the plunger 23 can be designed as a spring-loaded pressure piece. In contact with the chamfer of the opening 19c of the brewing cylinder 19, a driving force is then transferred from the douchette 9 to the brewing cylinder 19. Consequently, both movements are synchronized for a short time, and finally, the outer spindle nut 13 is screwed into the movement thread 3d of the outer spindle 3. As soon as the brewing cylinder 19 overtakes the douchette 9 due to the advance of the movement thread 3d of the outer spindle 3, the plunger 23 is compressed and then slides along the inner wall of the brewing cylinder 19 until it leaves the interior of the brewing cylinder 19 and is pushed back into its rest position into the filling opening 2b by the spring force. The challenge with this design is to select low-wear friction partners and contact surfaces that allow a large number of compression cycles.This results in a particularly simple design without complex seals for the hydraulic path 24a, 24b, 24c of the tappet 23.

[0113] Fig. 19 is a schematic longitudinal sectional view of the outer spindle nut 13 of the first feed gear 12 of the brewing carriage 2 and the holding device HR in the rest position of the brewing carriage 2. Fig. 20 shows a sectional view along line XX of Fig. 19.

[0114] The outer spindle nut 13 has an 8-shaped cross-section with a holding portion 13a and a threaded portion with an internal thread 13b (Fig. 20). The internal thread 13b corresponds to the external thread 3d of the outer spindle 3.

[0115] The outer spindle nut 13 is arranged in the receptacle 2c on an outer side of the brewing carriage 2 in an area facing the stamp plate 6 (see also Fig. 1, 2, 4, 5, 7, 8, 10, 12, 13, 15).

[0116] Furthermore, the outer spindle nut 13 is formed with two opposing coaxial receptacles 13c, which are arranged in the holding section 13a and belong to the holding device HR. A central axis of the receptacles 13c runs parallel to the outer spindle axis 3a or the central axis of the internal thread 13b. The two receptacles 13c are separated by a circumferential shoulder 13f. The shoulder 13 has a through hole.

[0117] The outer spindle nut 13 has end faces 13d and 13e. The first end face contact face 13d faces the punch plate 6 and a first pressure side 2d of the receptacle 2c. The second end face contact face 13e faces the drive plate 5 and a second pressure side 2e of the receptacle 2c.

[0118] The outer spindle 3 extends through through holes 2f of the brewing carriage 2 and through the internal thread 13b of the outer spindle nut 3.

[0119] The holding device HR here comprises a guide pin 28, sleeves 29, 29a, a compression spring 30, and a magnetic element 31. The guide pin 28 is arranged in the sleeves 29, 29a parallel to the outer spindle axis 3a and has a head 28a at its end facing the drive plate 5, the outer diameter of which corresponds to the outer diameter of the sleeve 29a, with the longitudinal axis of the guide pin 28 forming a pin axis 28b.

[0120] The sleeves 29, 29a are inserted into the receptacles 13c of the holding section 13a of the outer spindle nut 13 such that their respective ends arranged in the receptacles 13c rest against the circumferential shoulder 13f. The shoulder 13f forms an axial stop for both sleeves 29, 29a. The guide pin 28 extends through the two sleeves 29, 29a and the through-bore of the circumferential shoulder 13f.

[0121] The sleeves 29, 29a each protrude axially from the receptacles 13c with their other ends, with the sleeve 29 protruding in the direction of the plunger plate 6 together with the head 28a of the guide pin 28 into a through-bore 2g of the brewing carriage 2. The other sleeve 29a protrudes in the direction of the drive plate 5 into another through-bore 2h of the brewing carriage 2. The inner diameter of the through-bore 2h corresponds to the outer diameter of the sleeve 29a and the outer diameter of the head 28a of the guide pin 28. The through-bore 2h thus forms a sliding guide for the sleeve 29a and the head 28a.

[0122] The compression spring 30 is arranged around the sleeve 29a between the holding section 13a of the outer spindle nut 13 and the second pressure side 2e of the receptacle 2c of the brewing carriage 2. One end of the compression spring 30 is attached to the outer spindle nut 13, while the other end of the compression spring 30 contacts the second pressure side 2e of the receptacle 2c of the brewing carriage 2.

[0123] The magnetic element 31 is firmly connected, e.g. screwed, to the end of the guide pin 28 facing the stamp plate 6. The end of the magnetic element 31 facing the outer spindle nut 13 contacts the end of the sleeve 29 projecting towards the stamp plate 6. The end of the sleeve 29a facing the drive plate 5 contacts the head 28a of the guide pin 28. The sleeves 29 and 29a are clamped together or firmly arranged between the head 28a of the guide pin 28 and the magnetic element 31 and are also axially fixed to the holding section 13a of the outer spindle nut 13 by means of the circumferential shoulder 13f. The magnetic element 31 is cylindrical and arranged so as to be displaceable in the through-bore 2g of the brewing carriage 2. An inner diameter of the through-bore 2g corresponds to an outer diameter of the magnetic element 31.

[0124] In the rest position of the brewing carriage 2 shown in Fig. 19, the internal thread 13b of the outer spindle nut 13 and the movement thread 3d of the outer spindle 3 are disengaged. This state is also referred to as the "disengaged state." The contact side 13d of the outer spindle nut 13 facing the plunger plate 6 rests against the first pressure side 2d of the receptacle 2c of the brewing carriage 2.

[0125] The magnetic element 31 of the holding device HR is in contact with the inner side 6a of the plunger plate 6, which is made of a magnetically attractive metal, e.g., steel. The holding device HR thus fixes the outer spindle nut 13 and thus the brewing carriage 2 in its rest position. The spring force of the compression spring 30 also acts, pressing the outer spindle nut 13 toward the plunger plate 6 against the first pressure side 2d of the receptacle 2c of the brewing carriage 2.

[0126] In Fig. 20, one of two guide holes 2i for the guide rods 4 of the brewing carriage 2 is also shown.

[0127] Fig. 21 shows a schematic view of a drive side of the brewing unit 1 according to Figure 1 together with section lines for the following Figures 22 to 24.

[0128] Fig. 22-24 represent schematic sectional views along line XXI l-XXIII-XXIV in Figure 21.

[0129] Fig. 22 shows the rest position of the brewing carriage 2.

[0130] The brewing carriage 2 has a first end face 2j, which faces the drive plate 5. An opposite, second end face 2k of the brewing carriage 2 faces the plunger plate 6 and, in the rest position of the brewing carriage 2, is in contact with the inner side 6a of the plunger plate 4 as a stop.

[0131] In the rest position of the brewing carriage 2, the first end face 13d of the outer spindle nut 13 rests against the first pressure side 2d of the receptacle 2c of the brewing carriage 2, which faces the plunger plate 6. A clearance 32 is formed between the second end face 13e of the outer spindle nut 13, which faces the drive plate 5, and the associated second pressure side 2e, which faces the drive plate 5. The clearance 32 is also called "reverse clearance" and, in the example shown, is approximately 5 mm. This state is also referred to as "reverse clearance open."

[0132] The outer spindle nut 13 is “spindled out” and is located approximately 2 mm away from the thread runout of the movement thread 3d of the outer spindle 3.

[0133] The brewing carriage 2 is in this rest position shown or its first end position in the positions indicated above:

[0134] Closed position (first position, Fig. 1 -3) Filling position (second position, Fig. 4-6) Brewing position (third position Fig. 7-9)

[0135] In the closed position of the brewing unit 1 (see Fig. 1-3), the brewing carriage 2 is in the rest position and the douchette 9, together with the douchette sleeve 20, is fully retracted into the brewing cylinder 19 of the brewing carriage 2. The douchette 9 and plunger 10 are arranged close to one another or are in contact. The opening 19c of the brewing cylinder 19 below the filling opening 2b is closed by the douchette sleeve 20. The plunger 23 is in its second position and rests against the edge of the opening 19c facing the plunger plate 6.

[0136] To assume the filling position of the brewing unit 1, the plunger drive 24 is first deactivated by reducing the pressure, which also deactivates the seal 9a of the douchette 9. The douchette 9 and the connected douchette sleeve 20 are moved onto the drive plate 5 in the direction of movement BR 1 by means of the internal spindle 7. The plunger 23 is returned to its first position by the chamfer of the opening 19c (see Fig. 18). The douchette 9 is then in the filling position at the end of the brewing cylinder 19 facing the drive plate 5. The douchette sleeve 20, with its end section 20b, largely encloses the housing 15a of the second feed gear 15. The opening 19c to the filling opening 2b is free, and coffee powder can be filled into the brewing chamber 25 between the douchette 9 and the plunger 10 (Fig. 6).

[0137] Then, the douchette 9 is retracted into the brewing cylinder 19 to compress the coffee powder in the brewing chamber 25 and to assume the brewing position. Further filling of coffee powder and subsequent further compression can be performed by repeating the approach to the filling position and brewing position (Fig. 9).

[0138] After the brewing process has ended, the grounds ejection position is assumed. For this purpose, the carry-over position is achieved as shown in Fig. 10-11 by further retracting the shower head 9 in the direction of movement BR2 into the brewing cylinder 19 until the plunger 23 is below the opening 19c of the brewing cylinder 19. The plunger drive 24 is activated, whereby the shower head seal 9a is also pressurized. The inner spindle 7 then moves the shower head 9 in the direction of movement BR1 towards the drive plate 5. In its second position, the plunger 23 presses against the edge of the opening 19c of the brewing cylinder 19 and exerts a force in the direction of movement BR1 on this and thus on the brewing carriage 2. At the same time, this is supported by the friction of the shower head seal 9a in the brewing cylinder 19. The holding device HR with the magnetic element 31 detaches from the stamp plate 6, the reversal play (play 32) is passed through and overcome.The thread 13b of the outer spindle nut 13 and the movement thread 3d of the outer spindle 3 engage (also referred to as the "spindle insertion process"). The compression spring 30 of the holding device HR is preloaded because the outer spindle nut 13, with its second end face 13e facing the drive plate 5, is pressed against the corresponding second pressure side 2e of the receptacle 2c of the brewing carriage 2. The adjustment of the brewing carriage 2 in the direction of movement BR1 is then taken over by the outer spindle 3, and the plunger 23 is returned to its first position as described above in connection with Fig. 18. By further moving the brewing unit 1, the grounds ejection position (Fig. 14) is assumed.

[0139] This is also shown in section in Fig. 23. Now, the reversal clearance or clearance 32 is located between the first end face 13d facing the stamp plate 6 and the corresponding first pressure side 2d of the receptacle 2c of the brewing carriage 2. This state is also called "reversal clearance closed."

[0140] In the grounds ejection position, the douchette 9 is located at the end of the brewing cylinder 19 facing the stamp plate 6, whereby it has pressed out the coffee cake located in the brewing chamber 25, which then falls into a collecting container.

[0141] The brewing carriage 2 is in its intermediate position in the grounds ejection position of the brewing unit 1. By further moving the brewing unit 1 in the direction of movement BR1 toward the drive plate 5, the final position shown in Fig. 15-16 and Fig. 24 is assumed.

[0142] In the final position of the brewing unit 1, the brewing carriage 2 is in its second final position.

[0143] In this end position of the brewing unit 1, which is also the end position of the brewing carriage 2, the outer spindle nut 13 and the motion thread 3d of the outer spindle 3 are not loosened. The collar 7g of the inner spindle 7 forms the end position stop with the cover 16 of the second feed gear 15. The drive, e.g., the electric motor, is switched off by a limit switch (not shown) or a motor current monitor.

[0144] This end position serves, for example, as a reference for the positions of the brewing unit 1 and the positions of the brewing carriage 2.

[0145] To return the brewing carriage 2 to its rest position or first end position from its end position, the brewing unit 1 is moved in the direction of movement BR2 toward the plunger plate 6 until the outer spindle nut 13 and the movement thread 3d of the outer spindle 3 are unscrewed. In this case, the plunger 23 is previously moved into its second position by means of the plunger drive 24. The plunger 23 then rests against the edge of the opening 19c facing the plunger plate 6 and can thus transmit the movement of the douchette 9 in the direction of movement BR2 toward the plunger plate 6, since after unscrewing, the outer spindle 3 no longer transmits movement to the outer spindle nut 13 of the brewing carriage 2. The brewing carriage 2 is thus moved into the rest position by means of the movement of the shower head 9 in the direction of movement BR2, whereby the magnetic element 31 of the holding device HR fixes the brewing carriage 2 in the rest position on the inner side 6a of the stamp plate 6.

[0146] Figure 25 shows a schematic perspective view of a variant of the outer spindle nut 13'. A side view thereof is shown in Figure 26. Figure 27 shows a front view of a contact side 13e of the variant of the outer spindle nut 13'. Figure 28 shows a schematic side view of the brewing unit 1 with the variant of the outer spindle nut 13' according to Figures 25-27. Figure 29 shows a schematic sectional view of the variant of the outer spindle nut 13' in the installed state. The variant of the outer spindle nut 13' has some differences from the outer spindle nut 13 according to Figure 19.

[0147] In the variant, the guide pin 28 is formed integrally with the holding section 13a of the outer spindle nut 13', has a flattened portion 28c on one longitudinal side and protrudes from the contact side 13e of the outer spindle nut 13'.

[0148] The compression spring 30 is arranged on the guide pin 28. In the installed state (Figure 29), the compression spring 30 rests with one end on the second end / contact side 13e of the outer spindle nut 13' and with the other end, via a disc (not designated), on the pressure side 2e of the receptacle 2c of the brewing carriage 2.

[0149] The second end / contact side 13e of the threaded area of ​​the threaded end of the internal thread 13b of the outer spindle nut 13' is segmented with segments 33 in order to avoid canting between the outer spindle nut 13' and the movement thread 3d of the outer spindle 3 during the spindle insertion process.

[0150] The individual segments 33 each have a resilient effect, are arranged at a distance from one another on the circumference of the second end / contact side 13e of the outer spindle nut 13a around the internal thread 13b, ie around the thread end of the internal thread 13, and protrude from the second end / contact side 13e of the outer spindle nut 13'.

[0151] As soon as the tip and root diameters of the thread partners (internal thread 13b of the outer spindle nut 13' and the movement thread 3d of the outer spindle 3) tend to jam, individual segments 33 can spring back, i.e., spring radially outward. In this embodiment, eight segments 33 are provided, but a different distribution may also be useful. It is important that an individual segment 33 can resiliently deflect in the event of canting. If the design requires bouncing off both thread ends of the outer spindle 3, segmentation is also conceivable on the contact sides 13d, 13e of both thread ends of the internal thread 13b of the outer spindle nut 13.

[0152] The invention is not limited by the above-mentioned embodiment, but can be modified within the scope of the claims. It is conceivable that the movement functionality of the douchette 9 and the stamp

[0153] 10 in the brewing unit 1 can also be interchanged, i.e., arranged laterally inverted. Instead of the drive plate 5 and the plunger plate 6, a frame could also be used.

[0154] The magnetic element 31 can also be a controllable electromagnet. A mechanical locking mechanism in various designs is also conceivable, e.g., a releasable latch.

[0155] It is also conceivable that the shower head 9 could be driven along using a spring-loaded drive mechanism. This requires that the spindle also be extended in the second end position. Otherwise, the filling position can no longer be reached.

[0156] Reference symbol

[0157] 1 brewing unit

[0158] 2 brewing carriages

[0159] 2a Brewing carriage axis

[0160] 2b Filling opening

[0161] 2c recording

[0162] 2d, 2e print page

[0163] 2f, 2g, 2h through hole

[0164] 2i guide hole

[0165] 2j, 2k front side

[0166] 3 outer spindle

[0167] 3a Outer spindle axis

[0168] 3b Drive end

[0169] 3c End of camp

[0170] 3D motion thread

[0171] 4 guide rod

[0172] 4a Guide axis

[0173] 5 Drive plate

[0174] 6 stamp plate

[0175] 5a, 6a inside

[0176] 7 internal spindle

[0177] 7a Internal spindle axis

[0178] 7b Movement thread

[0179] 7c, 7d spindle end

[0180] 7th flattening

[0181] 7f thread runout

[0182] 7g bunch

[0183] 8 plate

[0184] 9 Shower

[0185] 9a Shower seal

[0186] 10 stamps

[0187] 10a Stamp seal

[0188] 11 , 11a side wall

[0189] 12 First feed gear

[0190] 13, 13' outer spindle nut

[0191] 13a stopping section

[0192] 13b internal thread

[0193] 13c Recording 13d, 13e Contact side

[0194] 13f shoulder

[0195] 13g segment

[0196] 14 Drive

[0197] 15 Second feed gear

[0198] 15a housing

[0199] 16 lids

[0200] 16a Long hole

[0201] 17 Internal spindle nut

[0202] 17a Collar

[0203] 17b internal thread

[0204] 17c Through hole

[0205] 18, 18a, 18b camp

[0206] 19 brewing cylinders

[0207] 19a, 19b front side

[0208] 19c Opening

[0209] 19d seal

[0210] 20 Duchette sleeve

[0211] 20a Floor

[0212] 20b final section

[0213] 20c line section

[0214] 20d recording

[0215] 21 Interior

[0216] 22 Tappet device

[0217] 23 plungers

[0218] 23a Tappet axis

[0219] 23b Tappet body

[0220] 23c Intermediate section

[0221] 23d, 23e fret

[0222] 24 tappet drive

[0223] 24a line

[0224] 24b cable connector

[0225] 24c line

[0226] 24d seal

[0227] 25 Brewing chamber

[0228] 25' drop zone

[0229] 26 tappet holder

[0230] 26a Collar

[0231] 26b Through opening 26c Guide body

[0232] 26d fastening section

[0233] 26e interior

[0234] 27, 27a Seal 28 Guide pin

[0235] 28a Head

[0236] 28b pin axis

[0237] 28c flattening

[0238] 29, 29a sleeve 30 compression spring

[0239] 31 Magnetic element

[0240] 32 games

[0241] 33 Segment BR, BR1. BR2 Direction of movement

[0242] HR holding device x, y, z coordinates

Claims

Claims Brewing unit (1) of a piston coffee machine, wherein the brewing unit (1) is designed as a spindle brewing unit with a brewing carriage (2) as a brewing chamber, two piston units as a douchette (9) and plunger (10), a drive motor and at least one gear, wherein the brewing unit (1) has a double spindle arrangement with an outer spindle (3) and an inner spindle (7), wherein the outer spindle (3) is coupled to the inner spindle (7) via the at least one gear, wherein the brewing carriage (2) is adjustable from a first end position into an intermediate position, then into a second end position and back again into the first end position, wherein the outer spindle (3) has a movement thread (3d) which engages with an outer spindle nut (13) arranged in the brewing carriage (2), characterized in thatthat the movement thread (3d) of the outer spindle (3) is disengaged from the outer spindle nut (13) in the first end position of the brewing carriage (2), wherein a speed of the brewing carriage (2) is zero, even if the outer spindle (3) continues to rotate, wherein the brewing carriage (2) is fixed in the first end position by means of a holding device (HR), and that the movement thread (3d) of the outer spindle (3) remains engaged with the outer spindle nut (13) in the second end position of the brewing carriage (2) and the drive motor is switched off. Brewing unit (1) according to claim 1, characterized in that the brewing carriage (2) has a first feed gear (12) with the outer spindle nut (13) and the holding device (HR). Brewing unit (1) according to claim 2, characterized in that the outer spindle nut (13) is arranged with an axial play (32) in a receptacle (2c) of the brewing carriage (2),wherein a first end / contact side (13d) of the outer spindle nut (13) is in contact with a first pressure side (2d) of the receptacle (2c) in the first end position, wherein a second end / contact side (13e) of the outer spindle nut (13) and a second pressure side (2e) of the receptacle (2c) are spaced apart by the play (32), and wherein the second end / contact side (13e) of the outer spindle nut (13) and the second pressure side (2e) of the receptacle (2c) are in contact and that, Play (32) is arranged between the first end-Z contact side (13d) of the outer spindle nut (13) and the first pressure side (2d) of the receptacle (2c) when the movement thread (3d) of the outer spindle (3) and the outer spindle nut (13) are in engagement.

4. Brewing unit (1) according to claim 3, characterized in that at least one contact side (13d, 13e) of the threaded region of the internal thread (13b) of the outer spindle nut (13') is segmented with segments (33), wherein the segments (33) are arranged spaced apart from one another on the circumference of the at least one contact side (13d, 13e) of the outer spindle nut (13a) around the internal thread (13b), each have a resilient effect and protrude from the respective contact side (13d, 13e) of the outer spindle nut (13').

5. Brewing unit (1) according to one of the preceding claims, characterized in that the inner spindle (7) is connected to the adjustable douchette (9) or the adjustable plunger (10) and is coupled to the drive via a second feed gear (15), and the plunger (10) or the douchette (9) is arranged in a stationary manner, wherein the adjustable brewing carriage (2) is guided so as to be longitudinally displaceable by means of the outer spindle (3) and at least one guide rod (4), and that the douchette (9) or the plunger (10) is guided so as to be longitudinally displaceable within the brewing carriage (2), wherein the brewing carriage (2) and the douchette (9) or the plunger (10) are adjustable at different speeds in common directions of movement (BR1, BR2).

6. Brewing unit (1) according to one of the preceding claims, characterized in that the douchette (9) is coupled to the brewing carriage (2) by means of an activated, controllable driver device when a coupling between the outer spindle (3) and the brewing carriage (2) via the first feed gear (12) and in the region of a reversal play of the outer spindle nut (13) in relation to the brewing carriage (2) is canceled in order to transmit the movement of the douchette (9) to the brewing carriage (2).

7. Brewing unit (1) according to claim 6, characterized in that the controllable driver device is designed as a controllable tappet device (22).

8. Brewing unit (1) according to claim 7, characterized in that the controllable tappet device (22) has a hydraulic, pneumatic, or mechanical tappet drive (24).

9. Brewing unit (1) according to claim 8, characterized in that the tappet drive (24) is connected to a hydraulically, pneumatically, or mechanically activatable shower seal (9a) of the shower (9).

10. Brewing unit (1) according to one of the preceding claims, characterized in that the holding device (HR) has a permanent magnet, an electrically controllable electromagnet or a mechanical lock.

11. Piston coffee machine with a brewing unit (1) according to one of the preceding claims.

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