Cartridge piston

Abstract

The invention relates to a cartridge piston (1) comprising: a piston base (2) which has a media side (3) and an actuating side (4); a piston shaft (5); and a first edge (6) which closes off the piston base, wherein a surface of the media side has at least three ridges (7) which extend outwards from the centre of the cartridge piston up to the first edge, wherein in each case two adjacent ridges and the first edge delimit regions (8), wherein each region forms a depression in the surface of the media surface opposite the ridges and the first edge, and wherein an opening (10), which fluidically connects the media side to the actuating side, is formed in each recess.

Description

[0001] Cartridge piston

[0002] The invention relates to a cartridge piston having a piston head with a media side and an actuation side, a piston shaft, and a first rim. Furthermore, the invention relates to a cartridge for storing a fluid having such a cartridge piston and a dispensing system having such a cartridge piston.

[0003] Such a cartridge piston, such a cartridge, and such a dispensing system are generally used in conjunction with guns for dispensing a fluid, for example an adhesive. Cartridges can have either a single fluid container with a single fluid or, for dispensing multi-component materials, two or more fluid containers, each containing a component of the material to be produced. If the cartridge has two or more fluid containers, a cartridge piston is arranged in each of the fluid containers to transport the respective fluid to outlets of the cartridge. For this purpose, the cartridge pistons can be displaced within the fluid containers and lie at least substantially sealingly against the inner walls of the fluid containers.

[0004] In this case, which is shown in Figure 1, a static mixer is used for discharge, which allows a single material stream to be created from two starting material streams. In a static mixer, the components are mixed to create a mixture that is as homogeneous as possible and exits the mixer as a mixture at its opening. Static mixers are characterized by the fact that they preferably have no moving parts, and the material streams to be mixed must be moved through them by means of a pumping function.EP 1 908 703 B1 relates to a cartridge piston having an upper side facing a cartridge content, a lower side, an outer wall, an inner support body and radial connecting webs between the outer wall and the inner support body, wherein a stiffening body connected to the connecting webs is arranged between the outer wall and the inner support body, wherein the connecting webs have a gap on the underside of the cartridge piston between the outer wall and the stiffening body, wherein the gap in the connecting webs extends at least to half the height of the cartridge piston.

[0005] It is an object of the invention to provide an improved cartridge piston. In particular, it is an object of the invention to provide a cartridge piston by means of which venting of the cartridge can be improved.

[0006] This object is achieved by a cartridge piston, a cartridge, and a dispensing system according to the independent claims. Advantageous embodiments are claimed in the dependent claims.

[0007] A first aspect of the invention relates to a cartridge piston, comprising a piston bottom with a media side and an actuation side, a piston shaft and a first edge which closes off the piston bottom, wherein a surface of the media side has at least three ridges which extend, in particular radially, from the center of the cartridge piston outwards to the first edge, wherein two adjacent ridges and the first edge each delimit regions, wherein each region forms a depression in the surface of the media surface opposite the ridges and the first edge, and wherein in each depression, in particular at the lowest point of the depression, an opening is formed which connects the media side to the actuation side in a fluid-communicating manner.

[0008] Preferably, the first edge is arranged on the media side in the region of the piston shaft. Further preferably, the at least three ridges meet in the center of the cartridge piston, forming a stem shape. A second aspect of the invention relates to a cartridge for storing a fluid with a cartridge piston.

[0009] A third aspect of the invention relates to a dispensing system with a cartridge and at least one attachment, in particular a mixer and / or a closure plug.

[0010] A media side within the meaning of the invention is preferably any side, in particular the front side, of the cartridge piston which, when the cartridge piston is used as intended, comes into contact with the medium, in particular fluid, which is stored in the cartridge.

[0011] Accordingly, an actuating side within the meaning of the invention is preferably that side, in particular the end face, of the piston crown from which the cartridge piston is actuated during intended use. Such actuation preferably takes place by means of a so-called pistol, into which a cartridge is inserted.

[0012] A burr in the sense of the invention is a spatially protruding kink in a surface.

[0013] The invention is based on the approach of gradually forcing a gas, particularly air, located between the medium with which the cartridge is filled and the piston inserted into the cartridge, toward openings in the cartridge piston when closing a filled cartridge. The gas can flow through these openings to the actuating side of the cartridge piston and thus reach the rear, open area of ​​the cartridge, where it can escape into the environment.

[0014] This is achieved in that the surface of the piston crown on the media side has at least three ridges. These three ridges divide the surface of the filled medium into different sections. The gas collects in the depressions, which are each formed in the areas between adjacent ridges and the first edge. With three ridges, this corresponds to three depressions. An opening is arranged in each of these depressions. The opening is preferably located in the area of ​​the first edge. Preferably, the cartridge piston has six ridges and correspondingly six openings. This results in a particularly advantageous division of the surface of the media side, in which the areas form something like isosceles triangles.

[0015] The gas bubbles that form in the recesses when the cartridge piston is pressed against the medium stored in the cartridge are pushed further toward the openings by the fluid as the cartridge piston is further moved within the cartridge. This can significantly reduce or even completely remove the amount of gas remaining on the medium side of the piston crown. This minimizes any reaction between the gas and the medium, or any negative influence of the gas on the medium during storage and / or dispensing.

[0016] When the burrs impact the medium, they distribute the medium to all sides of the surface of the media side of the piston crown. At the same time, the burrs cut into the medium. This significantly reduces the force required to move the cartridge piston or press the cartridge piston against the medium.

[0017] Due to their location in the recess, the openings 10 are also blocked by the medium relatively late. Preferably, the medium only reaches the holes after the gas has escaped from the cartridge.

[0018] Preferably, the openings are arranged in the region of the first edge or at the first edge. The invention takes advantage of the fact that the medium with which the cartridge is filled often forms a clump in the center of the cartridge. This clump first comes into contact with the ridges, and successively, other areas of the surface of the media side come into contact with the medium, with the air gradually escaping toward the first edge and thus toward the opening.

[0019] It is particularly advantageous if the opening is arranged at the lowest point of the recess, which is formed by the adjacent ridges and the first edge.

[0020] In an advantageous embodiment, the surface of the media side rises towards the center of the cartridge piston, particularly in the limited areas. The surface of the media side preferably has a curvature. Such a curvature is preferably convex. The rise towards the center of the cartridge piston promotes the flow of the medium filled in the cartridge from the center to the outer area of ​​the cartridge piston. This is particularly advantageous when the filled medium forms a clump in the center of the cartridge, as previously described. In addition, the rise reduces the actuating force that must be applied to move the cartridge piston. This actuating force is lower the smaller the area of ​​the media side that comes into contact with the medium at the same time.

[0021] In a further advantageous embodiment, the at least three ridges each have an edge and side surfaces sloping from the edge to the recesses. The ridges therefore preferably form the shape of a triangular prism. The edge and the sloping side surfaces ensure particularly effective displacement of the medium as the ridges penetrate the surface.

[0022] In a further advantageous embodiment, the rim has an edge and a surface sloping from this edge to the respective recess. This also promotes the displacement of the filled medium through the rim.

[0023] In a further advantageous embodiment, a groove is formed by the surface of the piston crown in the limited areas and the first edge, in which the openings are arranged. Preferably, the groove is interrupted, in particular exclusively, by the ridges. The groove also promotes the flow of gas to the openings through which the gas can escape to the actuating side.

[0024] In a further advantageous embodiment, the groove runs at least substantially parallel to the edge. This ensures that the groove is at essentially the same distance from the center of the cartridge at every point.

[0025] In a further advantageous embodiment of the cartridge piston, a first support wall is arranged on the actuation side, which is offset radially inward with respect to the piston shaft and runs parallel to it, forming a gap between the piston shaft and the first support wall. The first support wall makes the cartridge piston more rigid, and a sealing ring for the openings can be arranged in the gap.

[0026] In a further advantageous embodiment of the cartridge piston, the openings open into the gap. This allows the openings to be sealed by means of a sealing ring in the gap.

[0027] In a further advantageous embodiment, the cartridge piston has a sealing ring designed to cover the openings on the actuation side, in particular in an at least substantially fluid-tight manner. This allows the openings to be closed as soon as the cartridge piston is pressed against the medium filled in the cartridge.

[0028] A ring in the sense of the invention is an element which has an opening in its center.

[0029] In a further advantageous embodiment of the cartridge piston, the sealing ring can be arranged in the gap. This ensures particularly advantageous mounting of the sealing ring.

[0030] In a further advantageous embodiment of the cartridge piston, the sealing ring and the piston shaft and / or the support wall are designed such that the sealing ring can assume a closed position and an open position. In the closed position, the sealing ring covers the openings on the actuating side, in particular at least substantially in a fluid-tight manner, and in the open position promotes a fluid flow between the openings and the environment. This allows the sealing ring to be stored in the open position on the cartridge piston even before the openings are closed. Once the process of pressing the cartridge piston against the filled medium is complete, the sealing ring can be moved into the closed position.

[0031] In a further advantageous embodiment of the cartridge piston, the piston shaft and / or the first support wall has a first recess and a second recess, which are offset in the direction of a longitudinal axis of the cartridge piston, wherein the sealing ring has a projection that can engage in the first recess or the second recess. This embodiment represents a particularly simple definition of two stable positions of the sealing ring with respect to the piston shaft.

[0032] In a further advantageous embodiment, connecting webs extend inward from the first support wall. This allows for further stiffening of the cartridge piston.

[0033] In a further advantageous embodiment, a second support wall is arranged on the actuation side, which is offset radially inward relative to the first support wall and at which the connecting webs end. This also further stiffens the cartridge piston.

[0034] In a further advantageous embodiment of the cartridge piston, the piston shaft has at least one groove on its inner side and / or the first support wall on its outer side and / or the sealing ring has at least one groove in the direction of a longitudinal axis of the cartridge piston. The groove preferably runs, in particular exclusively, in the region of the first recess, which is further spaced from the piston crown and thus defines the opening position of the sealing ring. The groove promotes fluid flow between the openings and the surroundings in the opening position of the sealing ring.

[0035] In a further advantageous embodiment, the piston shaft has a second edge, wherein the second edge is arranged at the actuation-side end of the piston shaft. The second edge improves the centering of the cartridge piston in the cartridge. Furthermore, the second edge forms an additional seal against an inner wall of the cartridge.

[0036] In a further advantageous embodiment of the cartridge piston, the piston shaft has a third edge, wherein the third edge is preferably located approximately in the center of the piston shaft. The third piston edge also improves the centering of the cartridge piston in the cartridge and creates an additional seal.

[0037] The features and advantages described with respect to the first aspect of the invention apply accordingly to the second and third aspects of the invention, and vice versa. Further features and advantages will become apparent from the following description of exemplary embodiments with reference to the figures. They show, at least partially schematically:

[0038] Figure 1: a perspective top view of an embodiment of a

[0039] discharge system;

[0040] Figure 2: another perspective view of the embodiment of the

[0041] discharge system;

[0042] Figure 3: a plan view of the first embodiment of a

[0043] Discharge system according to Figures 1 and 2 onto the open side of the cartridge;

[0044] Figure 4: a cross-sectional view through the device shown in Figure 2

[0045] Example of a discharge system;

[0046] Figures 5 to 14: different views of a first embodiment of a cartridge piston; and

[0047] Figures 15 to 25: different views of a second embodiment of a cartridge piston.

[0048] Figure 1 shows an embodiment of a discharge system for fluids of a multi-component material.

[0049] Such a dispensing system is described below with reference to a two-component adhesive as a multi-component material. However, it will be obvious to those skilled in the art that the dispensing system can be used for dispensing any type of two-component material.

[0050] The dispensing system comprises a cartridge 22 and an attachment 24.

[0051] The attachment 24 is represented in Figure 1 by a so-called static mixer. Such a static mixer is characterized by the fact that it has no moving parts; rather, mixing is achieved by the movement of the two components through the mixer 24. The cartridge 22 has a first, larger fluid container 22a and a second, smaller fluid container 22b. The relative size of the fluid containers 22a, 22b results from the mixing ratio to be achieved with the dispensing system. It is therefore obvious to those skilled in the art that the sizes of the fluid containers 22a, 22b shown here are not limiting.

[0052] Furthermore, the cartridge 22 has a locking element 27, which in the illustrated embodiment is designed as a screw cap. The screw cap 27 is designed to interact with a shoulder or foot of the attachment 24 to seal the attachment 24 to the cartridge 22. Furthermore, the cartridge has a base (not shown) on which the locking element 27, designed as a screw cap, is mounted. In Figure 1, this base is largely hidden behind the screw cap 27.

[0053] Figure 2 shows another perspective view of the dispensing system. Unlike Figure 1, the open end of the cartridge 22 is visible, not the closed end.

[0054] Figure 2 now depicts a closure plug as attachment 24, which seals the cartridge 22 while the components contained in the cartridge are stored. In this case, the components cannot be dispensed.

[0055] The cartridge piston 1 can be seen in the opening of the larger fluid container 22a. A similar cartridge piston 1 is also present in the smaller fluid container 22b. However, due to the smaller opening, it is not visible in this view.

[0056] By moving the respective cartridge pistons 1 in the fluid containers 22a, 22b, pressure can be exerted on the media or components stored in the cartridges, causing them to be discharged through the opening of the fluid containers. In particular, these media or components are pressed through the static mixer. This preferably mixes them into a homogeneous mixture. Figure 3 shows a plan view of the opened side of the cartridge 22. Both cartridge pistons 1 in the larger fluid container 22a and the smaller fluid container 22b are now visible.

[0057] Figure 4 shows a cross-section through the discharge system according to Figures 2 and 3 along the section axis AA from Figure 3.

[0058] As can be seen in Figure 4, the two cartridge pistons 1 close the open sides of the larger fluid container 22a and the smaller fluid container 22b.

[0059] The two cartridge pistons 1 represent two embodiments, which are explained in detail below.

[0060] Figures 5 to 14 show various views of a first embodiment of a cartridge piston 1, as can be used in a larger fluid container 22a according to Figure 4. Identical elements are provided with the same reference numerals in Figures 5 to 14.

[0061] In the side view according to Figure 5, part of a curved piston crown 2 and a piston shaft 5 are visible. Furthermore, a sealing ring 14 is shown arranged separately. A first edge 6, a second edge 20 and a third edge 21 are arranged on the piston shaft 5. These edges serve to center and seal the cartridge piston with respect to an inner wall of a cartridge. The lower side of the piston crown 2 in Figure 5 forms the media side, which comes into contact with the medium in the cartridge during intended use. In Figure 5, a longitudinal axis of the cartridge piston 1 is also shown as a dashed line 17. The sealing ring 14 has a projection 18.

[0062] Figure 6 shows a perspective view of the cartridge piston 1, with the media side 3 of the piston visible. Figure 11 shows a corresponding top view of the media side 3 of the cartridge piston 1.

[0063] The media side 3 of the piston crown 2 is closed off by the first edge 6. The first edge 6 preferably has an edge 6a and surfaces 6b which slope down towards a center of the cartridge piston 1. Six ridges 7 are arranged on the piston crown 2, each having an edge 7a in its center and, on both sides of this edge 7a, surfaces 7b which slope down on both sides of the ridge 7. The six regions formed between two adjacent ridges 7 and the corresponding section of the first edge 6 form depressions opposite the ridges 7 and the first edge 6. The surface of these depressions is preferably convexly curved and slopes down towards the first edge 6 of the cartridge piston 1. A groove 11 is preferably formed between this outwardly sloping surface and the respective surface 6b of the edge 6 which then rises again outwards.An opening 10 is arranged in each of the grooves 11, preferably centrally between the ridges 7. This opening 10 connects the media side 3 with the actuation side 4 in a fluid-communicating manner.

[0064] Figure 7 shows a further perspective view of the cartridge piston 1, whereby, compared to Figure 6, the "back" or actuating side of the cartridge piston 1 is now visible.

[0065] A first support wall 12 is arranged concentrically to a piston skirt 5, with a gap 13 formed between the piston skirt 5 and the first support wall 12. This gap 13 is not visible in Figure 7 or Figure 8, since the sealing ring 14 is fully inserted into this gap 13. A second support wall 17 is also arranged concentrically to the piston skirt 5, but with a smaller radius than the first support wall 12. The first support wall 12 is connected to the second support wall 17 by connecting webs 26.

[0066] Grooves 19 are provided on the inside of the piston shaft 5 in a longitudinal direction of the cartridge piston 1.

[0067] Figure 12 shows a cross-section along the line BB through the cartridge piston 1 from Figure 11. The section BB is thus taken along an edge 7a of two ridges 7, which are arranged opposite one another with respect to the center of the cartridge piston 1.

[0068] The cross-section shows the media side 3 and the actuation side 4 of the piston crown 2. As can be seen from Figure 12, the edge 7a of the ridges 7 also has a convex curvature. Figure 8 shows a plan view of the actuation side of the cartridge piston according to Figures 5 to 7.

[0069] Figure 9 shows a further cross-section through the cartridge piston 1, but along the line AA from Figure 8. The section AA runs along two connecting webs 26, which are arranged on the actuation side 4 of the piston head 2. These are preferably offset from the ridges 7 on the media side 3 of the piston head 2. This results in even better stiffening of the piston head 2. Accordingly, the section AA runs transversely through regions 8, which are each delimited by two ridges 7 and the first edge 6. In Figure 9 it can be seen that the regions 8 are recessed compared to the edges 7a of the ridges 7 and that the regions 8 also have a convex curvature.

[0070] Figure 10 shows a detailed view from Figure 9, and Figure 13 shows a detailed view from Figure 12 of the respective cross-sections of the cartridge piston 1. The sealing ring 14 is shown in a disassembled position, as in the underlying Figures 9 and 12.

[0071] In particular, the detailed illustrations show the configuration of the gap 13, which is formed between the piston skirt 5 and the first support wall 12. This preferably has a first recess 15 and a second recess 16. These recesses 15, 16 are designed such that they can interact with a projection 18 of the sealing ring 14. When the projection 18 of the sealing ring 14 engages the first recess 15, the sealing ring is in an open position. In this position, air can escape from the recesses 8 in the piston crown 2 through the openings 10 into the gap 13 and from the gap 13 via the grooves 19, past the sealing ring 14, into the environment.This opening position of the sealing ring 14 is therefore suitable when the cartridge piston 1 is inserted into the respective fluid container 22a, 22b (not shown) and is moved in the direction of the filled medium so that the residual air in the fluid containers 22a, 22b can escape.

[0072] Once this process is fully completed, the sealing ring 14 is preferably pressed further into the gap 13 so that the projection 18 interacts with the second recess 16. In this position, the sealing ring 14 is in the closed position. Preferably, the sealing ring 14 closes the openings 10. Preferably, no more fluid can flow through the openings 10 in this closed position.

[0073] Figure 14 shows a detailed view of an area E in Figure 11. The detailed view essentially shows an area 8 of the piston crown 2. This is delimited by ridges 7, each with edges 7a and side surfaces 7b, as well as by the sloping surface 6b in the first edge 6. The area 8 forms a depression with respect to the ridges 7 and with respect to the first edge 6. Between the surface 6b sloping from the edge 6a of the edge 6 and the surface formed by the piston crown 2, a groove 11 is formed, which forms the deepest point of the depression. The opening 10, which connects the media side 3 to the actuation side 4 in a fluid-communicating manner, is preferably arranged in the center of the groove.

[0074] Figures 15 to 25 show various views of a second embodiment of a cartridge piston 1, which is suitable for the smaller fluid container 22b of the cartridge 22 according to Figure 4. Elements of the cartridge piston 1 shown here, which correspond to elements of the first embodiment of a cartridge piston 1 according to Figures 5 to 14, are designated by the same reference numerals.

[0075] The second embodiment of the cartridge piston 1 differs essentially in that the individual elements are more compact in the radial direction to the longitudinal axis of the cartridge piston 1 due to the reduced dimensions of the cartridge piston.

[0076] Figures 15, 16 and 17 show three views of the cartridge piston 1, with the sealing ring 14 in the disassembled position.

[0077] In contrast to the cartridge piston 1 of the first embodiment, the cartridge piston 1 of the second embodiment has only a single, first support wall 12, which is designed as a pin. The gap 13 is formed between this pin 12 and the piston shaft 5.

[0078] Furthermore, the cartridge piston 1 shown here also has a first rim 6 with an edge 6a and a sloping surface 6b, as well as ridges 7 with an edge 7a and two sloping surfaces 7b each. The ridges 7 essentially form the shape of a triangular prism. Here, too, the sealing ring 14 has a projection 18.

[0079] Figure 18 shows a perspective view according to Figure 17, wherein the sealing ring 14 is inserted into the gap 13 (not shown) and is thus in the closed position for closing the opening 10 (not shown).

[0080] Figure 19 shows a plan view of the cartridge piston 1 in the configuration according to Figures 15, 16 and 17 with the installed sealing ring 14.

[0081] Figure 20 shows a cross-sectional view along line AA in Figure 19.

[0082] The projection 18 can, in turn, interact with a first recess 15 or a second recess 16, which define an open position and a closed position of the sealing ring 14. In this case, both the projection 18 and the first recess 15 and the second recess 16 are preferably designed as circumferential elements. The piston crown 2 of the cartridge piston 1 shown here also has a media side 3 and an actuation side 4.

[0083] Figure 22 shows a top view of the media side 3 of the piston crown 2.

[0084] Figure 23 again shows a sectional view along line BB of Figure 22.

[0085] Again, section BB runs along the edges 7a of two ridges 7, which are opposite each other with respect to the center of the cartridge piston 1. Accordingly, the contour of edge 7a of ridges 7 can be seen in Figure 23. In Figure 20, however, the section runs through two opposite openings 10, so that the contour of the recesses in the areas 8 (not shown) becomes visible.

[0086] Figures 21 and 24 each show a detailed view C from Figure 20 and a detailed view D from Figure 23. In Figure 21, the recess in area 8 can be clearly seen. Only a part of the gap 13 is visible, in particular the second recess 16. In Figure 24, the contour of the edge 7a of the ridges 7 can be seen again. The second exemplary embodiment also has grooves 19 in the inner surface of the piston skirt 5, at least in the area of ​​the first recess 15, in order to enable air to escape from the gap 13 into the environment when the sealing ring is in the open position and its projection 18 interacts with the first recess 15 of the piston skirt 5. This groove 19 is only partially shown in Figure 23, however, since the majority of the first recess 15 is not shown in the view.

[0087] Figure 25 shows a detail E from Figure 22. Figure 25 shows the profile of the surface of the media side 3 of the piston crown 2. In contrast to the first embodiment, the groove 11 does not run concentrically with the first edge 6 of the cartridge piston 1. Furthermore, Figure 25 also shows the first edge 6 with its edge 6a and the surface 6b sloping toward the recess. Furthermore, various ridges 7 are visible in the respective edges 7a and the side surfaces 7b sloping from them.

[0088] It should be noted that the embodiments described above are merely examples and are not intended to limit the scope of protection, application, or structure in any way. Rather, the preceding description provides the skilled person with a guide for implementing at least one embodiment. Various modifications, particularly with regard to the function and arrangement of the described components, may be made without departing from the scope of protection as defined by the claims and equivalent combinations of features.

[0089] List of reference symbols

[0090] 1 cartridge piston

[0091] 2 piston crown

[0092] 3 Media page

[0093] 4 Operating side

[0094] 5 piston skirt

[0095] 6 Edge

[0096] 6a edge

[0097] 6b Area

[0098] 7 ridges

[0099] 7a edge

[0100] 7b Area

[0101] 8 areas

[0102] 10 Opening

[0103] 11 Gutter

[0104] 12 first retaining wall

[0105] 13 gap

[0106] 14 Sealing ring

[0107] 15 first recess

[0108] 16 second recess

[0109] 17 second retaining wall

[0110] 18 lead

[0111] 19 grooves

[0112] 20 second edge

[0113] 21 third edge

[0114] 22 cartridges

[0115] 22a first fluid container

[0116] 22b second fluid container

[0117] 24 Essay

[0118] 25 second retaining wall

[0119] 26 connecting bridges

[0120] 27 Locking element

Claims

Patent claims 1. A cartridge piston (1) comprising: a piston head (2) with a media side (3) and an actuation side (4), a piston shaft (5) and a first edge (6) which closes off the piston head (2), wherein a surface of the media side (3) has at least three ridges (7) which extend, in particular radially, from the center of the cartridge piston (1) outwards to the first edge (6), wherein two adjacent ridges (7) and the first edge (6) each delimit regions (8), wherein each region forms a depression in the surface of the media side (3) opposite the ridges (7) and the first edge (6), and wherein an opening (10) is formed in each depression, in particular at the lowest point of the depression, which opening connects the media side (3) to the actuation side (4) in a fluid-communicating manner.

2. Cartridge piston (1) according to claim 1, wherein the surface of the media side (3), in particular in the limited areas (8), rises towards the center of the cartridge piston (1) and preferably has a, in particular convex, curvature.

3. Cartridge piston (1) according to claim 1 or 2, wherein the at least three ridges (7) each have an edge (7a) and side surfaces (7b) sloping from the edge (7a) to the recesses (8).

4. Cartridge piston (1) according to one of the preceding claims, wherein the rim (6) has an edge (6a) and a surface (6b) sloping from this edge (6a) to the respective recess (8).

5. Cartridge piston (1) according to one of the preceding claims, wherein from the surface of the piston head (2) in the limited areas (8) and the first edge (6) forms a groove (11) in which the openings (10) are arranged.

6. Cartridge piston (1) according to claim 5, wherein the groove (11) runs at least substantially parallel to the edge (6).

7. Cartridge piston (1) according to one of the preceding claims, wherein a first support wall (12) is arranged on the actuating side (4), which is arranged radially offset inwards with respect to the piston shaft (5) and runs parallel to the latter, wherein a gap (13) is formed between the piston shaft (5) and the first support wall (12).

8. Cartridge piston (1) according to one of the preceding claims, wherein the openings (10) open into the gap (13).

9. Cartridge piston (1) according to one of the preceding claims, further comprising a seal (14) which is designed to cover the openings (10) on the actuating side (4), in particular at least substantially in a fluid-tight manner.

10. Cartridge piston (1) according to claim 9, wherein the seal (14) can be arranged in the gap (13).

11. Cartridge piston (1) according to claim 9 or 10, wherein the seal (14) and the piston shaft (5) and / or the first support wall (12) are designed in such a way that the seal (14) can assume a closed position and an open position, wherein the seal (14) in the closed position covers the openings (10) on the actuating side (4), in particular at least substantially in a fluid-tight manner, and in the open position promotes a fluid flow between the openings (10) and the environment.

12. Cartridge piston (1) according to one of the preceding claims, wherein the piston shaft (5) and / or the first support wall (12) has a first recess (15) and a second recess (16) which are arranged offset in the direction of a longitudinal axis (17) of the cartridge piston (1), and wherein the seal (14) has a projection (18) which is inserted into the first recess (15) or into the second recess (16).

13. Cartridge piston (1) according to one of the preceding claims, wherein the piston shaft (5) on its inner side and / or the first support wall (12) on its outer side and / or the seal (14) has at least one groove (19) in Direction of a longitudinal axis (17) of the cartridge piston (1).

14. Cartridge (22) for storing a fluid with a cartridge piston (1) according to one of the preceding claims.

15. Dispensing system with a cartridge (22) according to one of the preceding claims and at least one attachment (24), in particular a mixer and / or a closure plug.

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