Piston assembly and brewing device

Abstract

The invention relates to a piston assembly and a brewing device. The piston assembly is suitable for a brewing device. The piston assembly includes a piston body, a piston head mounted to an upper end of the piston body, and a tube extending at least partially in the piston body and the piston head and defining a flow path for introducing liquid into the brewing cartridge. The piston head is pivotable about an axis between a first position and a second position relative to the piston body. The tube is coupled to the piston head and is offset relative to the axis such that the tube rotates about the axis as the piston head pivots relative to the piston body. When the piston head is located at the first position, the pipe fitting can move downwards relative to the piston head so as to be separated from the piston head. When the piston head is located at the second position, the piston body prevents the pipe from moving downwards relative to the piston head. According to the piston assembly provided by the invention, the pipe fitting is relatively convenient to disassemble and assemble.

Description

Technical Field

[0001] The present disclosure relates to the field of beverage equipment, and in particular, to a piston assembly and a brewing device. Background Art

[0002] A brewing device can be used to make beverages such as coffee. The brewing device generally includes a brewing cylinder and one or two piston assemblies, which together form a brewing chamber. Pressurized hot water flows through the brewing chamber to brew the powder or granules to be brewed in the brewing chamber, such as coffee powder or granules, to obtain a beverage.

[0003] The piston assembly extending into the brewing cylinder from the lower end of the brewing cylinder can be called a lower piston assembly. A pipe fitting can be provided inside the lower piston assembly, and the made beverage can flow into the brewing chamber successively through the flow path defined by the pipe fitting. For a traditional brewing device, the process of installing the pipe fitting onto the main body part of the lower piston assembly and the process of disassembling the pipe fitting from the main body part are relatively inconvenient, which makes the disassembly and installation work of the pipe fitting time-consuming and laborious. Summary of the Invention

[0004] In view of this, the present disclosure provides a piston assembly and a brewing device having the same, aiming to improve the problem that the disassembly and installation work of the pipe fitting is time-consuming and laborious.

[0005] In a first aspect, the present disclosure provides a piston assembly, which is applied to a brewing device for making beverages. The brewing device includes the piston assembly and a brewing cylinder, and the piston assembly is configured to at least partially extend into the brewing cylinder from the lower end of the brewing cylinder. The piston assembly includes a piston body, a piston head, and a pipe fitting. The piston head is mounted on the upper end of the piston body. The pipe fitting at least partially extends in the piston body and the piston head and defines a flow path for introducing liquid into the brewing cylinder. The piston head is pivotable relative to the piston body between a first position and a second position about an axis. The pipe fitting is combined with the piston head and is offset relative to the above axis, so that as the piston head pivots relative to the piston body, the pipe fitting rotates about the axis. When the piston head is in the first position, the pipe fitting can move downward relative to the piston head to separate from the piston head. When the piston head is in the second position, the piston body prevents the pipe fitting from moving downward relative to the piston head.

[0006] According to the piston assembly provided in the first aspect of the present disclosure, it is only necessary to first rotate the piston head relative to the piston body from the second position to the first position, and then move the pipe fitting downward relative to the piston head, and the pipe fitting can be detached from the piston body and the piston head; correspondingly, it is only necessary to first move the pipe fitting upward relative to the piston head to combine the pipe fitting and the piston head, and then rotate the piston head relative to the piston body from the second position to the first position, and the pipe fitting can be fixed to the piston body and the piston head. Therefore, for the piston assembly provided by the present disclosure, the disassembly and installation work of the pipe fitting is relatively convenient.

[0007] In a possible implementation, the piston head is provided with a coupling portion, and the upper end of the piston body is provided with a mating portion. When the piston head is in the second position, the coupling portion is combined with the mating portion to fix the piston head to the piston body. When the piston head is in the first position, the coupling portion is separated from the mating portion.

[0008] According to this implementation, simply rotating the piston head relative to the piston body from the second position to the first position can both separate the coupling portion from the mating portion and unlock the downward movement of the pipe fitting, enabling the piston head to be directly removed from the piston body and the pipe fitting to be directly moved downward to be removed from the piston body and the piston head. Correspondingly, according to this implementation, after the pipe fitting is combined with the piston head upward, only by rotating the piston head relative to the piston body from the first position to the second position can both the coupling portion be combined with the mating portion and the downward movement be blocked, thereby achieving the fixation of the piston head to the piston body and the fixation of the pipe fitting to the piston body and the piston head.

[0009] In a possible implementation, one of the piston head and the piston body is provided with a shaft portion coinciding with the axis, and the other is provided with a shaft hole for the shaft portion to be inserted into and support the rotation of the shaft portion.

[0010] The shaft portion and the shaft hole with the above structure can provide support and guidance for the rotation of the piston head relative to the piston body, thereby improving the convenience of disassembly and assembly work.

[0011] In a possible implementation, the piston assembly further includes a fastener, and a part of the fastener extends into the shaft hole to be combined with the shaft portion; alternatively, the lower end of the shaft portion extends out of the shaft hole to be combined with the fastener.

[0012] In this way, the cooperation between the shaft portion and the shaft hole will not only provide support and guidance for the rotation of the piston head relative to the piston body, but also provide a basis for the fastener to fix the piston head to the piston body.

[0013] In a possible implementation, one of the piston head and the piston body is provided with a supporting peripheral wall surrounding the shaft portion, and the other is provided with a supporting concave portion for the supporting peripheral wall to be inserted into. The outer peripheral surface of the supporting peripheral wall and the inner surface of the supporting concave portion are in close contact, and the central axes of both coincide with the axis.

[0014] The cooperation between the outer peripheral surface of the supporting peripheral wall and the inner surface of the supporting concave portion can provide additional support and guidance for the rotation of the piston head relative to the piston body, thereby being able to provide protection for the shaft portion and reducing the risk of damage to the shaft portion.

[0015] In a possible implementation, the pipe fitting includes a pipe body and a joint fixed to the pipe body. The upper end wall of the piston body is provided with a through hole, which includes a large-diameter portion and a small-diameter portion that are in communication with each other. The joint can pass through the large-diameter portion and cannot pass through the small-diameter portion. When the piston head is in the first position, the joint is located above the large-diameter portion. When the piston head is in the second position, the joint is located above the small-diameter portion.

[0016] As the piston head pivots relative to the piston body between the first position and the second position, the piston head drives the pipe fitting to move, thereby causing the joint to move. After the piston head moves to the first position, the joint moves above the large-diameter portion. Since the large-diameter portion allows the joint to pass through, the downward movement of the joint located above the large-diameter portion will not be blocked. Therefore, when the joint is located above the large-diameter portion, the pipe fitting can be moved downward relative to the piston head, so that the pipe fitting is separated from the piston head and finally separated from the piston body. After the piston head moves to the second position, the joint moves above the small-diameter portion. Since the joint cannot pass through the small-diameter portion, the joint located above the small-diameter portion will be blocked and cannot move downward. Therefore, when the joint is located above the small-diameter portion, the pipe fitting cannot be separated from the piston head by moving the pipe fitting downward, and the pipe fitting will be reliably fixed to the piston head and the piston body.

[0017] In a possible implementation, the piston head is provided with a coupling portion, and the upper end of the piston body is provided with a mating portion; as the piston head pivots relative to the piston body from the second position to the first position, the coupling portion and the mating portion are switched from a coupled state to a separated state. The piston head is provided with a shaft portion that coincides with the axis, and the piston body is provided with a shaft hole for inserting the shaft portion and supporting the rotation of the shaft portion. The through hole is located on the outer peripheral side of the shaft hole, and the mating portion is located on the outer peripheral side of the through hole.

[0018] The shaft hole closer to the inside (i.e., closer to the axis) can cooperate with the shaft portion to provide support and guidance for the rotation of the piston head relative to the piston body. The circumferential dimension is larger towards the outer side, so the mating portion arranged on the outermost side allows itself and the corresponding coupling portion to have a larger dimension in the circumferential direction. The larger their circumferential dimension is, the higher their bonding strength is. The through hole is located in a central position, that is, it is more outward than the shaft hole and more inward than the mating portion, which enables the pipe fitting to obtain a suitable circumferential displacement as the piston head rotates relative to the piston body. Through this suitable displacement, the joint is sufficient to move from the first position to the second position, or vice versa. At the same time, this suitable displacement is not too large. If the displacement is too large, some unexpected consequences will occur. For example, if the displacement is too large, the piston body needs to provide a larger movement space, which is not conducive to the reasonable arrangement of other components or structures. Another example is that if the displacement is too large, the bending of the pipe fitting after rotation is larger, which will increase the risk of damage to the pipe fitting and also affect the flow rate or flow of the liquid in the pipe fitting.

[0019] In a possible implementation, the bottom of the piston head is provided with a socket hole extending in the up and down direction, and the joint is separably inserted into the socket hole to combine the pipe fitting with the piston head.

[0020] In this implementation, the combination of the pipe fitting and the piston head is achieved through the socket hole and the joint inserted therein, such that when the piston head rotates relative to the piston body, the pipe fitting can rotate relative to the piston body together with the piston head. When the piston head moves to the first position, by moving the pipe fitting, the joint can be pulled out of the socket hole downward or inserted into the socket hole upward. When the piston head moves to the second position, since the downward movement of the pipe fitting is blocked by the piston body, the joint cannot be pulled out of the socket hole downward, which reliably fixes the pipe fitting to the piston body and the piston head.

[0021] In a possible implementation, the bottom of the piston head is provided with a convex post extending downward, and the convex post forms the socket hole.

[0022] This implementation helps to reduce the weight of the piston head and the materials required for the piston head.

[0023] In a possible implementation, the pipe fitting includes a pipe body and a joint fixed to the pipe body. The upper end wall of the piston body is provided with a through hole, and the through hole includes a large-diameter portion and a small-diameter portion that communicate with each other. The joint can pass through the large-diameter portion and cannot pass through the small-diameter portion. When the piston head is in the first position, the joint is located on the large-diameter portion. When the piston head is in the second position, the joint is located above the small-diameter portion. The piston body is further provided with an abutting portion that extends upward from the top surface of the upper end wall and partially surrounds the small-diameter portion. When the piston head is in the second position, the joint abuts against the abutting portion.

[0024] When the piston head is in the second position relative to the piston body, the joint abuts against the abutting portion to prevent the pipe fitting from moving downward. Through the upward-extending abutting portion, when the joint abuts against the abutting portion, it will be in a relatively upper position, which is beneficial to reducing the length of the convex post. Considering that an overly long convex post is prone to accidental damage, this implementation helps to reduce the risk of damage to the convex post.

[0025] In a possible implementation, the piston head further includes a rib portion that extends to the convex post.

[0026] The rib portion with this structure can improve the overall strength of the piston head and at the same time can support the convex post to avoid accidental damage to the convex post.

[0027] Second aspect, the present disclosure provides a piston assembly for a brewing device. The brewing device further includes a brewing cylinder, and the piston assembly is configured to extend at least partially into the brewing cylinder from the lower end of the brewing cylinder. A flow path for introducing liquid into the brewing cylinder is provided in the piston assembly. The piston assembly includes a piston body and a piston head. The piston head is provided with a coupling portion, and the upper end of the piston body is provided with a mating portion. By rotating the piston head relative to the piston body about an axis, the coupling portion and the mating portion can be coupled or separated. The piston assembly further includes a fastener for detachably fastening the piston head to the piston body.

[0028] For the piston assembly provided according to the second aspect of the present disclosure, when disassembling the piston head from the piston body, the fastener can be removed first, and then the piston head is rotated relative to the piston body to separate the coupling portion and the mating portion, so that the piston head can be removed from the piston body; when installing the piston head onto the piston body, the piston head can be rotated relative to the piston body to couple the coupling portion and the mating portion, and then the fastener is fastened, so that the piston head can be reliably fixed to the piston body. This implementation method takes into account both the convenience of disassembling and assembling the piston head relative to the piston body and the firmness of the connection between the piston head and the piston body.

[0029] In a possible implementation, one of the coupling portion and the mating portion is a coupling convex portion and the other is a coupling concave portion, and the coupling concave portion can at least partially receive the coupling convex portion to be combined with the coupling convex portion.

[0030] This implementation has many advantages such as simple structure and easy implementation.

[0031] In a possible implementation, one of the piston head and the piston body is provided with a shaft portion coinciding with the axis, and the other is provided with a shaft hole for inserting the shaft portion and supporting the pivotal rotation of the shaft portion.

[0032] The shaft portion and the shaft hole with the above structure can provide support and guidance for the rotation of the piston head relative to the piston body, thereby improving the convenience of disassembly and assembly work.

[0033] In a possible implementation, a part of the fastener extends into the shaft hole from the lower end thereof to be combined with the shaft portion; or, the lower end of the shaft portion extends out of the shaft hole to be combined with the fastener.

[0034] In this way, the cooperation of the shaft portion and the shaft hole will not only provide support and guidance for the rotation of the piston head relative to the piston body, but also provide a basis for the fastener to fix the piston head to the piston body.

[0035] In a possible implementation, one of the piston head and the piston body is provided with a supporting peripheral wall surrounding the shaft portion, and the other is provided with a supporting concave portion for inserting the supporting peripheral wall. The outer peripheral surface of the supporting peripheral wall and the inner surface of the supporting concave portion are in close contact, and the central axes of both coincide with the axis.

[0036] The cooperation between the outer peripheral surface of the supporting peripheral wall and the inner surface of the supporting concave portion can provide additional support and guidance for the rotation of the piston head relative to the piston body, thereby protecting the shaft portion and reducing the risk of damage to the shaft portion.

[0037] In a possible implementation, the engaging portion is an engaging convex portion protruding inward from the inner peripheral surface of the supporting wall, the supporting concave portion is provided with a protruding portion protruding upward from its bottom surface, and the engaging portion is an engaging concave portion defined by the protruding portion. A plurality of engaging convex portions are circumferentially spaced apart, and a plurality of protruding portions defining a plurality of engaging concave portions are circumferentially spaced apart. By rotating the piston head relative to the piston body, each engaging convex portion can move between an engaging position located in a corresponding engaging concave portion and a release position disengaging from the engaging concave portion.

[0038] According to this structure of the piston body and the piston head, only by rotating the piston head relative to the piston body, it is possible to conveniently couple or separate the two, and the coupling between the two has relatively high strength.

[0039] In a possible implementation, as each engaging convex portion moves from the release position to the engaging position, it enters the engaging concave portion along the direction from the head end to the tail end of the engaging concave portion. The top surface of the engaging concave portion includes a guiding surface located at the head end of the engaging concave portion, and the guiding surface is configured to gradually extend downward as it approaches the tail end of the engaging concave portion.

[0040] The guiding surface having the above structure can guide the engaging convex portion, enabling the engaging convex portion to smoothly enter the engaging concave portion, which is beneficial to reducing the operation difficulty of installing the piston head onto the piston body and is beneficial to reducing the manufacturing precision required for the engaging convex portion and the engaging concave portion.

[0041] In a possible implementation, as each engaging convex portion moves from the release position to the engaging position, it enters the engaging concave portion along the direction from the head end to the tail end of the engaging concave portion. The tail end of the engaging concave portion is further provided with a blocking portion for blocking the engaging concave portion.

[0042] After the engaging convex portion enters the engaging concave portion along the direction from the head end to the tail end, the blocking portion will prevent the engaging convex portion from moving forward further, holding the engaging convex portion in the engaging concave portion, making it easy for the operator to perceive that the engaging convex portion and the engaging concave portion are well engaged. Without the blocking portion, the engaging convex portion that has entered the engaging concave portion is likely to leave the engaging concave portion again due to excessive rotation by the operator.

[0043] In a third aspect, the present disclosure also provides a brewing device, which includes the piston assembly provided in the first aspect or the second aspect above. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below.

[0045] It should be understood that the following drawings only show certain embodiments of the present disclosure and should not be regarded as limiting the scope.

[0046] It should also be understood that the same or similar reference numerals are used in the drawings to represent the same or similar elements.

[0047] It should further be understood that the drawings are only schematic, and the dimensions and ratios of the elements in the drawings are not necessarily accurate.

[0048] Figure 1 is a schematic structural diagram of a brewing device according to an embodiment of the present disclosure.

[0049] Figure 2 is Figure 1 a schematic structural diagram of the piston assembly of the brewing device in

[0050] Figure 3 is Figure 2 an exploded schematic diagram of the piston assembly in

[0051] Figure 4 is Figure 2 a longitudinal sectional schematic diagram of the piston assembly in

[0052] Figure 5 is Figure 2 a top view of the piston body of the piston assembly in

[0053] Figure 6 is Figure 5 an axonometric schematic diagram of the piston body in

[0054] Figure 7 and Figure 8 show Figure 2 the relative positional relationship between the piston body and the joint of the piston assembly in Figure 7 wherein in Figure 8 the joint is located above the large-diameter portion; in

[0055] Figure 9 is Figure 2 a schematic structural diagram of the piston head of the piston assembly in

[0056] Figure 10 is a schematic cross-sectional view taken along the A-A line in Figure 5

[0057] Figure 11 and Figure 12 show the relative positional relationship between the piston body and the pipe fitting according to a modification of the present disclosure, wherein in Figure 11 the pipe fitting is located in the release portion; in Figure 12 the pipe fitting is located in the clamping portion.​ Detailed implementation manners

[0058] The embodiments of the present disclosure will be described exemplarily below in conjunction with the accompanying drawings. It should be understood that there can be multiple implementation manners of the present disclosure, and it should not be construed as being limited to the embodiments described herein. The embodiments described herein are only for a more thorough and clear understanding of the present disclosure.

[0059] The present disclosure provides a brewing device 100. The brewing device 100 is used to make beverages, such as coffee. The brewing device 100 can be used independently or applied as a functional unit to a beverage machine, such as a coffee machine. It can be understood that the brewing device 100 is not limited to making coffee, and it can also be used to make other types of beverages. The present disclosure does not particularly limit the type of beverage made by the brewing device 100.

[0060] Referring to Figure 1 , the brewing device 100 may include a frame 10, piston assemblies 20, 30, a brewing cylinder 40, a driving device 50, and a transmission mechanism 60. The piston assemblies 20, 30, the brewing cylinder 40, the driving device 50, and the transmission mechanism 60 can be installed on the frame 10 to be supported by the frame 10. The piston assembly 20 may be referred to as the upper piston assembly 20, and the piston assembly 30 may be referred to as the lower piston assembly 30.

[0061] The driving device 50 can output power, and the power is transmitted to the brewing cylinder 40 through the transmission mechanism 60, so that the brewing cylinder 40 moves in the up-down direction relative to the upper piston assembly 20. For example, the driving device 50 can be a motor, and the transmission mechanism 60 can be a screw transmission mechanism. The upper end of the lower piston assembly 30 can extend into the brewing cylinder 40 to close the bottom end of the brewing cylinder 40. As the brewing cylinder 40 moves in the up-down direction, it will drive the lower piston assembly 30 to move together.

[0062] In Figure 1 , the brewing cylinder 40 is in a lower position. At this time, the upper piston assembly 20 is separated from the brewing cylinder 40, and the top end of the brewing cylinder 40 is open. The powder or granules to be brewed (such as coffee powder or granules) can be added into the brewing cylinder 40. As the brewing cylinder 40 rises, the lower end of the upper piston assembly 20 extends into the brewing cylinder 40 to jointly enclose a substantially closed brewing chamber with the brewing cylinder 40 and the lower piston assembly 30.

[0063] Flow paths are provided in both the upper piston assembly 20 and the lower piston assembly 30. Brewing liquid (such as hot water) can flow into the brewing chamber through the flow path of the lower piston assembly 30 to brew the powder or granules in the brewing chamber to obtain a beverage. The brewed beverage can flow out of the brewing chamber through the flow path in the upper piston assembly 20. The brewed beverage can be directly taken for drinking, or can be drunk after further processing.

[0064] It can be understood that although in the current example, the upper piston assembly 20 is fixed relative to the frame 10, and the brewing cylinder 40 and the lower piston assembly 30 are movable relative to the frame 10, in other examples, it can also be that the brewing cylinder 40 and the lower piston assembly 30 are fixed relative to the frame 10, and the upper piston assembly 20 is driven by the driving device 50 to move up and down.

[0065] Continue to refer to Figure 1 , the brewing device 100 may further include a feeder 70 and a channel member 80. The channel member 80 is installed on the feeder 70, and the feeder 70 is installed on the frame 10. The feeder 70 has a feeding channel in the shape of a funnel with a large upper end and a small lower end. The powder or granules to be brewed can be poured into the feeder 70 from above the feeder 70. The channel member 80 has a conveying channel. The conveying channel extends from the lower end of the feeder 70 to the upper end of the brewing cylinder 40 to deliver the powder or granules to be brewed into the brewing cylinder 40.

[0066] In an example where the brewing device 100 is applied to a coffee machine, a grinding device may be provided above the brewing device 100, and the grinding device can grind coffee beans into coffee powder or coffee granules. The feeder 70 can be used to receive the coffee powder or coffee granules from the grinding device and deliver the coffee powder or coffee granules to the channel member 80.

[0067] Continue to refer to Figure 1 , the brewing device 100 may further include a residue pushing member 90. After the brewing is completed, the brewing cylinder 40 will descend together with the lower piston assembly 30. After descending to a lower position, the lower piston assembly 30 is blocked and stops. As the brewing cylinder 40 descends to the lowest position, the lower piston assembly 30 will push the residue out of the brewing cylinder 40. Then, the residue pushing member 90 is driven to pivot, and further push the residue so that the residue falls from the top of the brewing cylinder 40.

[0068] Refer to Figures 2 to 4 , the lower piston assembly 30 may include a piston body 31 and a piston head 32. The piston head 32 can be installed at the upper end of the piston body 31. The piston head 32 can pivot relative to the piston body 31 about the axis A, Figure 4 The axis A is schematically shown. The piston head 32 can displace between a first position and a second position relative to the piston body 31 by pivoting relative to the piston body 31 about the axis A.

[0069] Continue to refer to Figures 2 to 4, the lower piston assembly 30 may further include a pipe fitting 33. The pipe fitting 33 may extend partially or entirely within the piston body 31 and the piston head 32 and define a flow path for introducing liquid into the brewing chamber 40. The pipe fitting 33 is coupled to the piston head 32 and is offset relative to the axis A (or, the pipe fitting 33 does not coincide with the axis A), such that as the piston head 32 pivots relative to the piston body 31 about the axis A, the pipe fitting 33 rotates about the axis A together with the piston head 31. When the piston head 32 is in the first position relative to the piston body 31, the piston body 31 allows the pipe fitting 33 to move downward relative to the piston head 32 to separate from the piston head 32; when the piston head 32 is in the second position relative to the piston body 31, the piston body 31 prevents the pipe fitting 33 from moving downward relative to the piston head 32 and maintains the pipe fitting 33 coupled to the piston head 32.

[0070] In this way, it is only necessary to first rotate the piston head 32 relative to the piston body 31 from the second position to the first position and then move the pipe fitting 33 downward relative to the piston head 32 to remove the pipe fitting 33 from the piston body 31 and the piston head 32; it is only necessary to first move the pipe fitting 33 upward relative to the piston head 32 to couple the pipe fitting 33 and the piston head 32 and then rotate the piston head 32 relative to the piston body 33 from the second position to the first position to fix the pipe fitting 33 to the piston body 31 and the piston head 32. Therefore, the disassembly and installation of the pipe fitting 33 are relatively convenient.

[0071] Referring to Figure 6 and Figure 9 , the piston head 32 may further be provided with a coupling portion 325, and the upper end of the piston body 31 may be provided with a mating portion 314. As Figure 4 shown, when the piston head 32 is in the second position, the coupling portion 325 is combined with the mating portion 314 to fix the piston head 32 to the piston body 31. Correspondingly, when the piston head 32 is in the first position, the coupling portion 325 is separated from the mating portion 314.

[0072] According to this implementation, only by rotating the piston head 32 relative to the piston body 31 from the second position to the first position, it is possible to both separate the coupling portion 325 from the mating portion 314 and release the pipe fitting 33 to allow it to move downward, so that the piston head 32 can be removed from the piston body 31 and the pipe fitting 33 can be directly moved downward to be removed from the piston body 31 and the piston head 32. Correspondingly, according to this implementation, after the pipe fitting 33 is coupled upward with the piston head 32, only by rotating the piston head 32 relative to the piston body 31 from the first position to the second position, it is possible to both combine the coupling portion 325 with the mating portion 314 and prevent the downward movement of the pipe fitting 33, thereby fixing the piston head 32 to the piston body 31 and fixing the pipe fitting 33 to the piston body 31 and the piston head 32.

[0073] The piston head 32 is usually provided with a filter screen 35. After being used for a period of time, residues or grease will be deposited on the filter screen 35, which will cause some unexpected consequences, such as deteriorating the quality of the beverage. In the current implementation of the present disclosure, since the piston head 32 can be detached from the piston body 31, when it is difficult to clean the whole or part of the piston head 32 (for example, the filter screen 35 on the piston head 32) or when its service life expires, the piston head 32 can be modularly replaced without replacing the entire piston assembly 30, which is beneficial to reducing the maintenance cost of the brewing device 100.

[0074] Reference Figure 9 , the piston head 32 may be provided with a shaft portion 326 extending downward from its lower end surface 3221. The shaft portion 326 may coincide with the axis A, or rather, the shaft portion 326 may define the axis A. In combination with Figure 6 , the piston body 31 may be provided with a shaft hole 316 adapted to receive the shaft portion 326. The shaft portion 326 and the shaft hole 316 having the above structure can provide support and guidance for the rotation of the piston head 32 relative to the piston body 31, thereby improving the convenience of disassembly and assembly work. It can be understood that in other examples, it may also be that the piston body 31 is provided with a shaft portion 326 and the piston head 32 is provided with a shaft hole 316.

[0075] Continue to refer to Figure 6 and Figure 9 , the piston head 32 is provided with a supporting peripheral wall 327 surrounding the shaft portion 326, and the piston body 31 is provided with a supporting recess 317 for inserting the supporting peripheral wall 327. The outer peripheral surface of the supporting peripheral wall 327 and the inner surface of the supporting recess 317 are in close contact with each other, and the central axes of both coincide with the axis A. The cooperation between the outer peripheral surface of the supporting peripheral wall 327 and the inner surface of the supporting recess 317 can provide additional support and guidance for the rotation of the piston head 32 relative to the piston body 31, thereby being able to provide protection for the shaft portion 326 and reducing the risk of damage to the shaft portion 326.

[0076] It can be understood that although in the drawings, the piston head 32 is provided with a supporting peripheral wall 327 surrounding the shaft portion 326, and the piston body 31 is provided with a supporting recess 317 for inserting the supporting peripheral wall 327, in other examples of the present disclosure, they may also have other structures. For example, in an alternative example, the piston body 31 is provided with a supporting peripheral wall 327 surrounding the shaft portion 326, and the piston head 32 is provided with a supporting recess 317 for inserting the supporting peripheral wall 327.

[0077] There are various ways for the piston body 31 to releasably prevent the pipe fitting 33 from moving downward, and the present disclosure does not make special restrictions. As one implementation, refer to Figures 3 to 6, the pipe fitting 33 may include a pipe body 331 and a joint 332 fixed to the pipe body 331. A through hole 312 may be provided on the upper end wall 311 of the piston body 31. The through hole 312 may include a large-diameter portion 3121 and a small-diameter portion 3122. The joint 332 can pass through the large-diameter portion 3121 and cannot pass through the small-diameter portion 3122. For example, the outer diameter of the joint 332 is greater than the inner diameter of the small-diameter portion 3122 and less than the inner diameter of the large-diameter portion 3121. As Figure 7 shown, when the piston head 32 is in the first position relative to the piston body 31, the joint 332 is located above the large-diameter portion 3121. As Figure 8 shown, when the piston head 32 is in the second position relative to the piston body 31, the joint 332 is located above the small-diameter portion 3122.

[0078] As the piston head 32 pivots between the first position and the second position relative to the piston body 31, the piston head 32 drives the pipe fitting 33 to move, thereby causing the joint 332 to move. After the piston head 32 moves to the first position, the joint 332 moves above the large-diameter portion 3121. Since the large-diameter portion 3121 allows the joint 332 to pass through, the downward movement of the joint 332 located above the large-diameter portion 3121 will not be blocked. Therefore, when the joint 332 is located above the large-diameter portion 3121, the pipe fitting 33 can be moved downward relative to the piston head 32 to separate the pipe fitting 33 from the piston head 31 and finally from the piston body 32. That is to say, when the joint 332 is located above the large-diameter portion 3121, the piston body 31 releases the pipe fitting 33. When the piston head 32 moves to the second position, the joint 332 moves above the small-diameter portion 3122. Since the joint 332 cannot pass through the small-diameter portion 3122, the joint 332 located above the small-diameter portion 3122 will be blocked and unable to move downward. Therefore, when the joint 332 is located above the small-diameter portion 3122, the pipe fitting 33 cannot be separated from the piston head 32 by moving the pipe fitting 33 downward, so as to prevent the pipe fitting 33 from moving downward.

[0079] In addition, according to this implementation method, when installing the pipe fitting 33, the pipe fitting 33 can be first assembled with the piston head 32, and then their whole can be assembled with the piston body 31; in this case, the larger aperture of the large-diameter portion 3121 allows the pipe fitting 33 to pass through to allow the smooth installation of the piston body 31. Optionally, when installing the pipe fitting 33, the piston head 32 and the piston body 31 can also be first assembled, and then their whole can be assembled with the pipe fitting 33; in this case, the larger aperture of the large-diameter portion 3121 allows the pipe fitting 33 to pass through to allow the smooth installation of the pipe fitting 33. The operator can freely choose between the above two installation methods according to the needs without considering the installation sequence of the entire lower piston assembly 30, and the installation is flexible and convenient.

[0080] In some examples, the tube body 331 and the joint 332 can be two relatively independent components. The joint 332 can be installed on the tube body 331 to be fixed to the tube body 331. For example, the joint 332 can be threadedly connected to, adhesively bonded to, welded to, or press-fitted with the tube body 331. In some examples, the tube body 331 and the joint 332 can be integrally formed, and the whole of the two is an independent component.

[0081] Reference Figures 5 to 6 , the through hole 312 can be located on the outer peripheral side of the shaft hole 316, and the fitting portion 314 can be located on the outer peripheral side of the through hole 312. The inner (i.e., closer to the axis) shaft hole 316 can cooperate with the shaft portion 326 to provide support and guidance for the rotation of the piston head 32 relative to the piston body 31. The circumferential dimension will be larger towards the outer side. Therefore, the fitting portion 314 arranged on the outermost side allows itself and the corresponding engaging portion 325 to have a larger dimension in the circumferential direction. The larger their circumferential dimension, the higher their bonding strength. The through hole 312 is located in a central position, that is, more outward than the shaft hole 316 and more inward than the fitting portion 314. This enables the pipe fitting 33 to obtain a suitable circumferential displacement as the piston head 32 rotates relative to the piston body 31. Through this suitable displacement, the joint 332 is sufficient to move from the first position to the second position, or vice versa. At the same time, this suitable displacement is not too large. If the displacement is too large, some unexpected consequences will occur. For example, if the displacement is too large, the piston body 31 needs to provide a larger movement space, which is not conducive to the reasonable arrangement of other components or structures. Another example is that if the displacement is too large, the bending of the pipe fitting 33 after rotation is larger, which will increase the risk of damage to the pipe fitting 33 and also affect the flow rate or flow volume of the liquid in the pipe fitting 33.

[0082] There are various ways to combine the pipe fitting 33 and the piston head 32, and the present disclosure does not make special restrictions on this. As an implementation method, reference Figure 9 , the bottom of the piston head 32 is provided with a plug hole 321 extending in the up and down direction. The joint 332 can be inserted upward into the plug hole 321 to combine the pipe fitting 33 and the piston head 32, and the joint 332 can be pulled out downward from the plug hole 321 to separate the pipe fitting 33 and the piston head 32.

[0083] In this implementation, the connection between the pipe fitting 33 and the piston head 32 is achieved through the insertion hole 321 and the connector 332 inserted therein, such that when the piston head 32 rotates relative to the piston body 31, the pipe fitting 33 can rotate relative to the piston body 31 together with the piston head 32. When the piston head 32 moves to the first position, by moving the pipe fitting 33, the connector 332 can be pulled out of the insertion hole 321 downward, or the connector 332 can be inserted into the insertion hole 321 upward. When the piston head 32 moves to the second position, since the pipe fitting 33 is blocked by the piston body 31, the connector 332 cannot be pulled out of the insertion hole 321 downward, which reliably fixes the pipe fitting 33 to the piston body 31 and the piston head 32.

[0084] Continuing to refer to Figure 9 , a convex post 323 extending downward can be provided at the bottom of the piston head 32, and the convex post 323 forms the insertion hole 321. This implementation helps to reduce the weight of the piston head 32 and the materials required for the piston head.

[0085] Referring to Figure 4 , the piston body 31 can also be provided with an abutting portion 313. The abutting portion 313 can extend upward from the upper surface of the upper end wall 311 of the piston body 31 and partially surround the small-diameter portion 3122. Combining Figure 6 , when the piston head 32 is in the second position, the connector 332 can abut against the upper end surface of the abutting portion 313.

[0086] When the piston head 32 is in the second position relative to the piston body 31, the connector 332 abuts against the abutting portion 313 to reliably prevent the pipe fitting 33 from being moved downward. Through the upward-extending abutting portion 313, when the connector 332 abuts against the abutting portion 313, it will be in a relatively upper position, which is beneficial to reducing the length of the convex post 323. Considering that an overly long convex post 323 is prone to accidental damage, this implementation helps to reduce the risk of damage to the convex post 323.

[0087] Referring again to Figure 9 , a rib 324 extending downward can also be provided at the bottom of the piston head 32, and the rib 324 can extend to the convex post 323. The rib 324 having such a structure can improve the overall strength of the piston head 32 and at the same time can support the convex post 323 to avoid accidental damage to the convex post 323.

[0088] It should be noted that the piston head 32 can be provided with multiple ribs 324. It can be that only one rib 324 extends to the convex post 323, or multiple ribs 324 all extend to the convex post 323.

[0089] There are various ways to assemble the piston body 31 and the piston head 32. As one implementation, referring to Figure 4 、 Figure 6 andFigure 9 , as introduced above, the piston head 31 may be provided with a coupling portion 325, and the upper end of the piston body 31 may be provided with a mating portion 314. By rotating the piston head 32 relative to the piston body 31, the coupling portion 325 and the mating portion 314 can be coupled or separated. At the same time, the lower piston assembly 30 may further include a fastener 34 for detachably fastening the piston head 32 to the piston body 31. For example, the fastener 34 may be a bolt or a nut.

[0090] When disassembling the piston head 32 from the piston body 31, the fastener 34 can be removed first, and then the piston head 31 can be rotated relative to the piston body 32 to separate the coupling portion 325 from the mating portion 314, and then the piston head 32 can be removed from the piston body 32. When installing the piston head 32 onto the piston body 31, the piston head 32 can be rotated relative to the piston body 31 to couple the coupling portion 325 with the mating portion 314, and then the fastener 34 can be tightened, so that the piston head 32 can be reliably fixed to the piston body 31. This implementation method takes into account both the convenience of disassembling and assembling the piston head 32 relative to the piston body 31 and the firmness of the connection between the piston head 32 and the piston body 31.

[0091] Coupling Figure 4 , a part of the fastener 34 can extend into the shaft hole 316 from the lower end thereof to be coupled with the shaft portion 326. Alternatively, the lower end of the shaft portion 326 can extend downward out of the shaft hole 316 to be coupled with the fastener 34.

[0092] In this way, the cooperation between the shaft portion 326 and the shaft hole 316 will not only provide a basis for the fastener 34 to fix the piston head 32 to the piston body 31, but also be able to provide support for the rotation of the piston head 32 relative to the piston body 31.

[0093] There are various ways for the fastener 34 to be coupled with the shaft portion 326, and the present disclosure does not make any special restrictions thereon. For example, in some examples, the shaft portion 326 may be provided with a threaded hole, and the fastener 34 may be a screw or a bolt. In another example, the shaft portion 326 may be provided with an external thread, and the fastener 34 may be a nut that can be threadedly coupled therewith.

[0094] There are various implementation methods for the coupling portion 325 and the mating portion 314, and the present disclosure does not make any special limitations thereon. For example, in some examples, one of the coupling portion 325 and the mating portion 314 is a coupling convex portion, and the other is a coupling concave portion, and the coupling concave portion can at least partially receive the coupling convex portion to be combined with the coupling convex portion. This implementation method has many advantages such as simple structure and easy implementation.

[0095] It can be understood that although in the current example, the engaging portion 325 is presented as an engaging convex portion, and the mating portion 314 is implemented as an engaging concave portion adapted to receive the engaging convex portion, in other examples of the present disclosure, the two may also have other configurations. For example, in an alternative example, the engaging portion 325 may be an engaging concave portion, and the mating portion 314 may be an engaging convex portion.

[0096] Referring Figure 9 , in a non-limiting example, the engaging portion 325 is an engaging convex portion 325 protruding inward from the inner circumferential surface of the supporting peripheral wall 327, and the mating portion 314 is an engaging concave portion 314 defined by a protruding portion 315 on the bottom surface provided with a supporting concave portion 317. The piston head 32 may be provided with a plurality of engaging convex portions 325, and the plurality of engaging convex portions may be circumferentially spaced apart. The piston body 31 may be provided with a plurality of protruding portions 315, and the plurality of protruding portions 315 may be circumferentially spaced apart and respectively define a plurality of engaging concave portions 314. By rotating the piston head 32 relative to the piston body 31, each engaging convex portion 325 can move between an engaging position in a corresponding engaging concave portion 314 and a release position disengaged from the engaging concave portion. According to this configuration of the piston body 31 and the piston head 32, it is only necessary to rotate the piston head 32 relative to the piston body 31 to conveniently couple or separate the two, and the coupling between the two has a relatively high strength.

[0097] Referring Figure 10 , each engaging concave portion 314 may have a leading end 3141 and a trailing end 3142. As each engaging convex portion 325 moves from the release position to the engaging position, it enters the engaging concave portion 314 along the direction from the leading end 3141 to the trailing end 3142 of the corresponding engaging concave portion 314. The top surface of the engaging concave portion 314 may include a guiding surface 3143 located at the leading end 3141 of the engaging concave portion 314, and the guiding surface 3143 may be configured to gradually extend downward as it approaches the trailing end 3142 of the engaging concave portion 314.

[0098] The guiding surface 3143 having the above configuration can guide the engaging convex portion 325, enabling the engaging convex portion 325 to smoothly enter the corresponding engaging concave portion 314. This is beneficial to reducing the operation difficulty of installing the piston head 32 onto the piston body 31 and is also beneficial to reducing the manufacturing precision required for the engaging convex portion 325 and the engaging concave portion 314.

[0099] Continuing to refer Figure 10, a blocking portion 3144 for blocking the engaging recess 314 may also be provided at the tail end of each engaging recess 314. When the engaging protrusion 325 enters the engaging recess 314 along the direction from the head end 3141 to the tail end 3142, the blocking portion 3144 will prevent the engaging protrusion 325 from advancing further, and hold the engaging protrusion 325 in the engaging recess 314, so that the operator can easily perceive that the engaging protrusion 325 and the engaging recess 314 are well engaged. Without the blocking portion 3144, the engaging protrusion 325 that has entered the engaging recess 314 may easily leave the engaging recess 314 again due to excessive rotation by the operator.

[0100] Reference Figure 3 and Figure 4 , the lower piston assembly 30 may further include a first seal 36. In combination Figure 4 , the first seal 36 may surround the peripheral wall portion 327 to provide a certain degree of sealing effect and reduce the risk of foreign objects entering the interior of the lower piston assembly 30 through the gap between the piston head 32 and the piston body 31. Continuing to refer to Figure 3 and Figure 4 , the lower piston assembly 30 may further include a second seal 37. The second seal 37 may be located between the first seal 36 and the peripheral wall portion 327 of the piston head 32 to further reduce the risk of foreign objects entering the interior of the lower piston assembly 30 through the gap between the piston head 32 and the piston body 31.

[0101] Continuing to refer to Figure 4 , the lower piston assembly 30 may further include a fastener 38. The fastener 38 may be used to fasten the filter screen 35 to the piston head 32. For example, the fastener 38 may be a screw or a bolt, which may pass through the through hole on the filter screen 35 and be threadedly engaged with the threaded hole on the piston head 32, thereby fastening the filter screen 35 to the piston head 32.

[0102] The piston body 31a according to another variant of the present disclosure is shown in Figure 11 and Figure 12 . The piston body 31a is substantially the same as the piston body 31 described above. For the sake of brevity, the differences between the piston body 31a and the piston body 31 will be emphasized below, and the repeated descriptions will be appropriately omitted.

[0103] Reference Figure 11 and Figure 12 , a through hole 312a may be provided on the upper end wall 311a of the piston body 31a. The through hole 312a may include a release portion 3121a and a clamping portion 3122a. The outer diameter of the pipe fitting 33a may be slightly larger than the inner diameter of the clamping portion 3122a and smaller than the inner diameter of the release portion 3121a. As Figure 11 shown, when the piston head 32 is in the first position relative to the piston body 31a, the pipe fitting 33a is located in the release portion 3121a. As Figure 12As shown, when the piston head 32 is in the second position relative to the piston body 31a, the pipe fitting 33a is located in the clamping portion 3122a.

[0104] As the piston head 32 pivots between the first position and the second position relative to the piston body 31a, the piston head 32 drives the pipe fitting 33a to move. After the piston head 32 moves to the first position, the pipe fitting 33a moves to the release portion 3121a. Since the inner diameter of the release portion 3121a is larger than the outer diameter of the pipe fitting 33a, the pipe fitting 33a can move in the up and down directions. Therefore, when the pipe fitting 33a is located in the release portion 3121a, the pipe fitting 33a can be moved downward relative to the piston head 32 so that the pipe fitting 33a is separated from the piston head 31 and finally separated from the piston body 31a. After the piston head 32 moves to the second position, the pipe fitting 33a moves to the clamping portion 3122a. Since the outer diameter of the pipe fitting 33a is slightly smaller than the inner diameter of the clamping portion 3122a, the pipe fitting 33a will be clamped and fixed by the clamping portion 3122a and cannot move downward. Therefore, when the pipe fitting 33a is located in the clamping portion 3122a, the pipe fitting 33a cannot be separated from the piston head 32 by moving the pipe fitting 33a downward.

[0105] It should be noted that, in the above specific embodiments, the various elements described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combinations. For example, in some examples, the outer periphery of the piston body and the inner wall of the piston head can be respectively provided with cooperating flanges and chutes so that the piston can rotate relative to the piston body about the above axis.

[0106] It should be understood that multiple components and / or parts can be provided by a single integrated component or part. Alternatively, a single integrated component or part can be divided into multiple separate components and / or parts. The disclosure of "a" or "an" used to describe a component or part is not intended to exclude other components or parts.

[0107] It should be understood that although terms such as "first" or "second" may be used in the present disclosure to describe various elements, these elements are not defined by these terms, and these terms are only used to distinguish one element from another.

[0108] The protection scope of the present disclosure is not limited to the above embodiments. Any person skilled in the art within the technical scope disclosed by the present disclosure can think of changes or substitutions, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A piston assembly of a brewing device, the brewing device further comprising a brewing cylinder, the piston assembly being configured to extend at least partially into the brewing cylinder from a lower end of the brewing cylinder, the piston assembly including a piston body, a piston head, and a pipe member, the piston head being mounted on an upper end of the piston body, the pipe member at least partially extending through the piston body and the piston head and defining a flow path for introducing liquid into the brewing cylinder, characterized in that: The piston head is pivotable relative to the piston body about an axis between a first position and a second position; the pipe member is coupled to the piston head and offset relative to the axis such that as the piston head pivots relative to the piston body, the pipe member rotates about the axis; When the piston head is in the first position, the pipe member is capable of moving downward relative to the piston head and separating from the piston head; when the piston head is in the second position, the piston body prevents the pipe member from moving downward relative to the piston head.

2. The piston assembly according to claim 1, wherein, The piston head is provided with a coupling portion, and the upper end of the piston body is provided with a mating portion; when the piston head is in the second position, the coupling portion is combined with the mating portion to fix the piston head to the piston body; when the piston head is in the first position, the coupling portion is separated from the mating portion.

3. The piston assembly according to claim 1 or 2, characterized in that, One of the piston head and the piston body is provided with a shaft portion coinciding with the axis, and the other is provided with a shaft hole for inserting the shaft portion and supporting the rotation of the shaft portion.

4. The piston assembly according to claim 3, wherein, The piston assembly further includes a fastener, a part of the fastener extending into the shaft hole to be combined with the shaft portion; or, the lower end of the shaft portion extends out of the shaft hole to be combined with the fastener.

5. The piston assembly according to claim 3, wherein, One of the piston head and the piston body is provided with a supporting peripheral wall surrounding the shaft portion, and the other is provided with a supporting recess for inserting the supporting peripheral wall; the outer peripheral surface of the supporting peripheral wall and the inner surface of the supporting recess are in close contact with each other, and the central axes of both coincide with the axis.

6. The piston assembly according to claim 1, wherein, The pipe member includes a pipe body and a joint fixed to the pipe body, an upper end wall of the piston body is provided with a through hole, the through hole including a large-diameter portion and a small-diameter portion communicating with each other, the joint being capable of passing through the large-diameter portion and not being capable of passing through the small-diameter portion; when the piston head is in the first position, the joint is located above the large-diameter portion; when the piston head is in the second position, the joint is located above the small-diameter portion.

7. The piston assembly according to claim 6, characterized in that, The piston head is provided with a coupling portion, and the upper end of the piston body is provided with a mating portion; as the piston head pivots relative to the piston body from the second position to the first position, the coupling portion and the mating portion are switched from a combined state to a separated state; the piston head is provided with a shaft portion coinciding with the axis, and the piston body is provided with a shaft hole for inserting the shaft portion and supporting the rotation of the shaft portion; the through hole is located on the outer peripheral side of the shaft hole, and the mating portion is located on the outer peripheral side of the through hole.

8. The piston assembly according to claim 6, wherein The bottom of the piston head is provided with a plug hole extending in the up-and-down direction, and the joint is detachably inserted into the plug hole to combine the pipe member with the piston head.

9. The piston assembly according to claim 8, wherein, The bottom of the piston head is provided with a convex column extending downward, and the convex column forms the insertion hole.

10. The piston assembly according to claim 9, characterized in that, The pipe fitting includes a pipe body and a joint fixed to the pipe body. A through hole is provided in the upper end wall of the piston body. The through hole includes a large-diameter portion and a small-diameter portion that communicate with each other. The joint can pass through the large-diameter portion and cannot pass through the small-diameter portion; when the piston head is in the first position, the joint is located above the large-diameter portion; when the piston head is in the second position, the joint is located above the small-diameter portion; the piston body is further provided with an abutting portion that extends upward from the top surface of the upper end wall and partially surrounds the small-diameter portion; when the piston head is in the second position, the joint abuts against the abutting portion.

11. The piston assembly according to claim 9, characterized in that, The piston head further includes a rib portion that extends to the convex column.

12. A piston assembly of a brewing device, the brewing device further including a brewing cylinder. The piston assembly is configured to at least partially extend into the brewing cylinder from the lower end of the brewing cylinder. A flow path for introducing liquid into the brewing cylinder is provided in the piston assembly. The piston assembly includes a piston body and a piston head, and is characterized in that: The piston body head is provided with a coupling portion, and the upper end of the piston body is provided with a mating portion. By rotating the piston head relative to the piston body about an axis, the coupling portion and the mating portion can be coupled or separated. The piston assembly further includes a fastener for detachably fastening the piston head to the piston body.

13. The piston assembly according to claim 12, wherein, One of the coupling portion and the mating portion is a coupling convex portion and the other is a coupling concave portion, and the coupling concave portion can at least partially receive the coupling convex portion to be combined with the coupling convex portion.

14. The piston assembly according to claim 12, wherein One of the piston head and the piston body is provided with a shaft portion that coincides with the axis, and the other is provided with a shaft hole for inserting the shaft portion and supporting the pivotal rotation of the shaft portion.

15. The piston assembly according to claim 14, wherein, A part of the fastener extends into the shaft hole from the lower end thereof to be combined with the shaft portion; or, the lower end of the shaft portion extends out of the shaft hole to be combined with the fastener.

16. The piston assembly according to claim 14, characterized in that, One of the piston head and the piston body is provided with a supporting peripheral wall surrounding the shaft portion, and the other is provided with a supporting concave portion for inserting the supporting peripheral wall; the outer peripheral surface of the supporting peripheral wall and the inner surface of the supporting concave portion are in close contact with each other, and the central axes of both coincide with the axis.

17. The piston assembly according to claim 14, characterized in that, The coupling portion is a coupling convex portion protruding inward from the inner peripheral surface of the supporting wall. The supporting concave portion is provided with a protruding portion protruding upward from its bottom surface. The mating portion is a coupling concave portion defined by the protruding portion. A plurality of coupling convex portions are circumferentially spaced apart and respectively define a plurality of coupling concave portions. A plurality of protruding portions are circumferentially spaced apart. By rotating the piston head relative to the piston body, each coupling convex portion can move between a coupling position in a corresponding coupling concave portion and a release position where it disengages from the coupling concave portion.

18. The piston assembly according to claim 17, wherein, As each engaging projection moves from the release position to the engaging position, it enters the engaging recess along a direction from the leading end to the trailing end of the engaging recess, wherein the top surface of the engaging recess includes a guiding surface located at the leading end of the engaging recess, and the guiding surface is configured to gradually extend downward as it approaches the trailing end of the engaging recess.

19. The piston assembly according to claim 17, wherein, As each engaging projection moves from the release position to the engaging position, it enters the engaging recess along a direction from the leading end to the trailing end of the engaging recess, wherein a blocking portion for blocking the engaging recess is further provided at the trailing end of the engaging recess.

20. A brewing device, characterized in that, The brewing device includes the piston assembly according to any one of claims 1 to 19.

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