Patent Grant
10786790
The present invention relates to a static mixer for mixing together at least two components comprising: a mixer housing; a mixing element having an upstream end with at least two entry openings; a mixing head having at least two inlets provided at an input side and at least two outlets provided at an output surface; and a separating wall disposed between the output surface and the upstream end for separating the components leaving the outlets. The invention further relates to a dispensing apparatus.
A wide variety of ways of dispensing two-component masses from cartridges is known in the prior art. The materials to be dispensed are typically a matrix material and a hardener. Two-component materials are typically used as impression materials, e.g. on the formation of dental impressions, as a cement material for prosthetic restorations, as a temporary cement for trial cementing restorations or for cementing temporary crowns. Further applications of two-component materials are in the building industry where they are e.g. used as a replacement for mechanical joints that corrode over time. Adhesive bonding can be used to bond products such as windows and concrete elements. The use of multi-component protective coatings, for example moisture barriers, corrosion protection and anti-slip coatings, is also becoming increasingly common.
The filled cartridges come in different ratios referred to as 1:1, 2:1, 4:1 and 10:1 etc., the numbers specifying the ratios of the amounts of each of the two materials that are to be dispensed. The reason for these different ratios is to allow a wide variety of different compositions to be mixed and dispensed. For example some compositions require more hardener and some require less hardener. Also some compositions require more mixing.
Static mixers, also referred to as mixing tips, are generally known from the prior art. The static mixers are adapted to mix the compositions as they exit the cartridge. In this respect different length and different diameter mixing tips are provided to ensure a thorough through mixing of the various two-component mixtures. The mixing tips typically have an insert resembling e.g. an open spiral which forces the two-components into contact with one another and exerts forces on them causing them to mix.
The individual components of the multi-components to be mixed are frequently fairly expensive so there is a need to reduce the volume of material lost after a mixing process has taken place. To reduce the volume remaining in a static mixer specific designs have been implemented resulting in a reduced length of the static mixer. However, the reduction in length has led to very complicated designs since a reduction in length normally adversely affects the through mixing of the multi-components. Generally speaking, a shorter length of the static mixer has to be balanced by a more improved design in order to prevent a deterioration of the through mixing of the multi-components. Since the static mixers are frequently manufactured by injection molding, their production has become very demanding in effort and cost, as highly complex molds are necessary.
Therefore, it is an object of the present invention to provide a static mixer in which the through mixing of the multi-components is improved, on the one hand, without excessively increasing the residue of the multi-component material being left after use, i.e. without excessively increasing the length of the static mixer, and, on the other hand, without excessively complicating the design of the static mixer.
This object is satisfied by a static mixer having the features of claim 1.
In particular such a static mixer is suitable for mixing together at least two components and comprises: a mixer housing; a mixing element having an upstream end with at least two entry openings and a downstream end, the mixing element being arranged at least partly within the mixer housing; a mixing head having at least two inlets provided at an input side and at least two outlets provided at an output surface, wherein each of the at least two inlets is in fluid communication with one of the at least two outlets; and a separating wall disposed between the output surface and the upstream end of the mixing element for separating the components leaving the outlets.
The static mixer is characterized in that the separating wall comprises a free downstream edge which is disposed with respect to at least one of the entry openings of the mixing element so as to allow at least partial flows of the components separated by the separating wall to combine after exceeding the downstream edge and to jointly enter said at least one of the entry openings.
Providing such a separating wall, on the one hand, ensures that the mixing element being arranged at least partly within the mixer housing is uniformly supplied with the components. On the other hand, the separating wall positions the components relative to each other such that at least one of the entry openings of the actual mixing element already is supplied with a mixed flow consisting of at least two components. In other words, a streak consisting of at least two partial flows of the components is fed into at least one entry opening. This ensures an optimum mixing result and hence permits a reduction in the length of the mixing element. A reduction in length of the static mixer leads to a reduction in any residual volume that is left in the static mixer after its use.
In this connection it should be noted that the feature according to which the mixing element is at least partly provided within the housing means that at least mixer elements of the mixing element are arranged within the mixer housing and that, for example, components of the separating wall or the mixing head may project out of the mixer housing. However, it is preferred if at least the mixing element and the separating wall are arranged within the mixer housing.
Preferably the separating wall can have a meandering pattern. By “meandering” it is meant that the separating wall comprises a winding and a turning course. For example, the separating wall may comprise zigzag, sinusoidal, undulating or step-like patterns. The separating wall may also comprise combinations of the aforementioned patterns, i.e. different wall segments with different patterns.
Advantageously the pattern of the separating wall may be designed such that each entry opening of the mixing element is fed with at least two partial flows of the components, i.e. each entry opening is supplied by a streak consisting of at least one partial flow of each component.
The separating wall may comprise at least two linear segments. Optionally, the separating wall may comprise at least two segments being parallel to each other. In general, a segment is a part or a section of the separating wall being separated from another part or section of the separating wall by a winding or turning. For example, two segments being parallel to each other may be interconnected by at least one other segment, wherein the other segment can either be curved or linear.
In a preferred embodiment, the separating wall comprises a curved segment, a linear segment, a linear or curved segment, a linear segment and a curved segment in the sequence stated. In this embodiment, it is particularly preferred if the two linear segments flanking the one linear or curved segment are parallel to each other.
It is preferred if the separating wall comprises thickened segments for reducing a volume accessible for the components when leaving the outlets of the mixing head. The thickened segments preferably may have a greater wall thickness than other segments of the separating wall. By varying the thickness of the separating wall or its segments, the volume occupied by the components after leaving the outlets can be adjusted. Advantageously narrowing this volume leads to a reduction in the residual volume of components left behind in the static mixer after its use. The accessible volume is thereby defined as the free space between the outlets of the mixing head and the entry openings of the mixing element. In particular, the thickened segments may be provided for reducing the free space between the outlets of the mixing head and the entry openings of the mixing element.
Having regard to a mixing ratio of 1:1, it is particularly preferred if the volume accessible for each component after leaving the outlet essentially is the same. Maintaining the same volume for both components particularly prevents an undue forerunning of either of the components.
However, having regard to higher mixing ratios like 2:1, 4:1 or 10:1 etc., it can be preferable to reduce the volume for one component in favour of another component to be added in higher volumes.
In some embodiments it can be of advantage if the separating wall partially frames or surrounds at least one outlet at the outlet surface and/or at least one entry opening at the upstream end of the mixing element. Such a design leads to an improved flow path of the components between the output surface of the mixing head and/or the upstream end of the mixing element and the components can enter the entry openings at an optimum spot.
In this connection it can be preferred that the separating wall at least partially cooperates with the mixer housing, preferably with an inner surface of the mixer housing, to provide a component flow guide region at the entry openings of the mixing element. In other words, the separating wall can be at least partially aligned flush with a wall of the mixer housing. In this context it can be further preferred that the separating wall and the wall of the mixer housing essentially have the same thickness, at least at points where the separating wall and the wall of the mixer housing cooperate or are aligned flush.
In a preferred embodiment the separating wall can be integrally formed with the mixing element or with the mixing head. In this context, the mixing head and the mixing element can be held together in an axial direction by means of a plug connection preferably formed by the separating wall cooperating with the mixing element or with the mixing head. The plug connection can also be formed by other plug and counter plug elements being assigned to the mixing element or the mixing head.
Optionally, the separating wall can be integrally formed with the mixing element and with the mixing head, thereby forming a one-piece construction. Advantageously the separating wall, the mixing head and the mixing element can be a one-piece construction formed by injection molding. It is further preferred if the mixer housing and the aforementioned one-piece construction are formed as separate elements. It is also conceivable if the mixer housing, the mixing head, the mixing element and the separating wall are formed as separate elements.
In some embodiments it can be of advantage if the static mixer further comprises an intermediate wall disposed between the upstream end of the mixing element and the separating wall.
Preferably, the intermediate wall can define two sides, wherein each side is assigned to at least one outlet of the mixing head and/or to at least one entry opening of the mixing element. It is particularly preferred if each of the two sides defined by the intermediate wall is respectively assigned to exactly one outlet.
Advantageously the intermediate wall can be disposed such that an entry opening is assigned to each side defined by the intermediate wall. It is particularly preferred if the intermediate wall separates one entry opening on the one side and two entry openings on the other side. Expediently, the intermediate wall can be disposed to not traverse one of the entry openings of the mixing element. In other words, the intermediate wall can be disposed to run between the entry openings.
The intermediate wall can be disposed to divide the components separated by the separating wall by at least partially traversing the separating wall. Expediently, the intermediate wall can traverse at least one linear segment of the separating wall at an angle of between 70° and 110°, preferably between 80° and 100°, more preferably between 85° and 95°, in particular of approximately 90°.
The intermediate wall can extend essentially linear and/or can have the same height as the separating wall. As regards further patterns or shapes the intermediate wall can have reference is made to the above explanations on the separating wall. The intermediate wall can be at least partially, but preferably fully, arranged within the mixer housing.
The intermediate wall can preferably be integrally formed with the mixing element. The intermediate wall also can be integrally formed with the separating wall, wherein the separating wall preferably can be integrally formed with the mixing head. In either case, a plug connection can be provided to connect the mixing element and the mixing head. Expediently, the mixing element, the intermediate wall, the separating wall and the mixing head can be a one-piece construction, preferably formed by injection molding.
In a preferred embodiment the static mixer further comprises at least one flow obstruction disposed between the upstream end of the mixing element and the output surface of the mixing head for deflecting the components or at least partial flows of the components.
Advantageously the at least one flow obstruction can be disposed between the downstream edge of the separating wall and the upstream end of the mixing element or between the downstream edge of the separating wall and an upstream edge of the intermediate wall. However, it is particularly preferred if the at least one flow obstruction is essentially disposed in one plane with the downstream edge of the separating wall or if it is disposed adjacent to the downstream edge of the separating wall.
Providing such a flow obstruction prevents an undue forerunning of either of the components after leaving the outlets of the mixing head and guarantees a uniform distribution of the partial flows of the components to the entry openings of the mixing element.
The at least one flow obstruction can preferably be planar and can preferably have an even upper and lower surface. For instance, the flow obstruction can have a rectangular, triangular, semi-circular, lenticular or crescent shape. Expediently the thickness of the flow obstruction can be equal to or smaller than the thickness of the separation wall and/or the intermediate wall.
It is preferred if at least one, in particular exactly one, flow obstruction is assigned to an opening cross-section defined by one of the at least two outlets. In other words, the flow obstruction can preferably partly overlap with the opening cross-section of one outlet. This particularly ensures that the components when leaving the outlets at first fully occupy a volume located below the respective flow obstruction before proceeding further towards the mixing element. In this context, the flow obstruction acts as a kind of deflector or intermediate stopper.
The static mixer can preferably have a longitudinal axis and at least two flow paths extending between the at least two inlets and outlets, wherein each inlet and outlet has a geometric center. The geometric center of each of the at least two outlets and inlets can preferably be equally spaced apart from the longitudinal axis. However, it can be preferred that the geometric center of at least one, preferably of each, of the at least two outlets being spaced less far apart from the longitudinal axis than the geometric center of at least one, preferably of each, of the at least two inlets.
The mixing element can advantageously comprise a plurality of mixer elements arranged one after another for a repeated separation and re-combination of streams of the components to be mixed.
For an as good as possible mixing result the mixing element can comprise mixer elements for separating the material to be mixed into a plurality of streams, as well as means for the layered merging of the same. Those elements and means include a transverse edge and guide walls that extend at an angle to said transverse edge, as well as guide elements arranged at an angle to the longitudinal axis and provided with openings. The mixing element comprises a transverse edge and a following transverse guide wall and at least two guide walls ending in a separating edge each with lateral end sections and with at least one bottom section disposed between said guide walls. Thereby at least one opening on one side of said transverse edge and at least two openings on the other side of said transverse edge is defined.
Alternatively, the mixing element can comprise mixer elements for separating the material to be mixed into a plurality of streams, as well as means for the layered merging of the same, including separating edges and a transverse edge that extends at an angle to said separating edges, as well as deflecting elements arranged at an angle to the longitudinal axis and provided with openings. The mixing element comprises at least two separating edges with following guide walls with lateral end sections and with at least one bottom section disposed between said guide walls, and a transverse edge arranged at one end of a transverse guide wall. Thereby at least one opening on one side of said transverse edge and at least two openings on the other side of said transverse edge is defined.
In a preferred embodiment, the mixing element can have three entry openings, one being arranged on one side of said traverse edge and two being arranged on the other side of said traverse edge.
Details regarding the design of such a mixing element are described in European Patent EP-B-1 426 099, which is incorporated by reference to the extent that it discloses such a mixing element.
Advantageously the intermediate wall can correspond to a first transverse guide wall of the upstream end of the mixing element.
Since according to the present invention at least partial flows of the components already jointly enter at least one of the entry openings of the mixing element, the separation and re-combination process can result in a higher number of streams or streaks after the components having passed through a first mixer element of the mixing element. This significantly improves the mixing result and allows for a reduction in length of the static mixer.
The mixer elements of the mixing element can preferably be held together by struts, wherein the struts can also act as further guide and deflecting walls. Expediently, the struts can make direct contact with the mixer housing when the mixing element is arranged within the housing. The struts thus can act as guide for the mixer housing during assembly.
In a further aspect, the present invention relates to a dispensing apparatus comprising a multi-component cartridge and a static mixer as described in the foregoing that is connected to the multi-component cartridge, with the multi-component cartridge preferably being filled with respective components.
In still a further aspect the present invention relates to a use of a static mixer of the kind described herein or a dispensing apparatus of the kind described herein in order to dispense components from a multi-component cartridge via the static mixer.
Further embodiments of the invention are described in the following description of the figures. The invention will be explained in the following in detail by means of embodiments and with reference to the drawing in which is shown:
In the following the same reference numerals will be used for parts having the same or equivalent function. Any statements made having regard to the direction of a component are made relative to the position shown in the drawing and can naturally vary in the actual position of application.
The mixing element 14 and part of the mixing head 22 are arranged within the mixer housing 12. The mixer housing 12, in particular the wider housing section 11, can further comprise a connection element for establishing a connection to a cartridge (not shown). For example, the connection element can be a sleeve in which the narrow housing section 15 can be received. The sleeve can have an internal thread for establishing a screwed joint and/or means for establishing a bayonet coupling to the cartridge. Further, the mixing head and/or the sleeve can be provided with connection means for establishing a plug connection with the cartridge.
The mixing head 22 has two inlets 24a, 24b provided at an input side 26. Each of the two inlets 24a, 24b is in fluid communication with a corresponding outlet 28a, 28b provided at an output surface 30. The inlets 24a, 24b are of the same size as the outlets 28a, 28b. The inlets 24a, 24b are of the same size as the outlets 28a, 28b. Also, the inlets 24a, 24b and the outlets 28a, 28b among each other are of the same size. Further, a flow channel defined by inlet 24a and outlet 28a has the same volumetric capacity as a corresponding flow channel defined by inlet 24b and outlet 28b.
The separating wall 32 is arranged between the output surface 30 and the intermediate wall 36. The separating wall 32 partly surrounds the outlet 28b and comprises two thickened segments 35 and further segments 34a, 34b, 34c (see
The intermediate wall 36 is located at an upstream end 16 of the mixing element 14 and is disposed between the separating wall 32 and a first mixer element 42. The intermediate wall 36 traverses the separating wall 32 and defines two sides 38a, 38b, wherein the side 38a is assigned to the outlet 28a of the mixing head 22 and to two entry openings 20a, 20b of the mixing element 14. The side 38b is assigned to outlet 28b and one entry opening 20c. This becomes more obvious in
The mixing element 14 comprises several successive mixer elements 42, wherein each mixer element 42 comprises a transverse guide wall 45 with a transverse edge 44, followed by two guide walls 46a, 46b each extending at a 90° angle to the transverse guide wall 45 and each having a separating edge 48. A bottom section 50 having a bottom edge 51 at its lower side is disposed between the two guide walls 46a, 46b. The bottom edge 51 divides the lower side of the bottom section 50 into two sloping parts 49a, 49b. Further, each of the guide walls 46a, 46b has one lateral end section 52a, 52b. Thereby three openings for the components to pass through are defined. One opening is defined on a side 54b of the transverse edge 44 and two openings are defined on a side 54a of the transverse edge 44. The arrangement of the openings corresponds to the arrangement of the entry openings 20a, 20b, 20c, which is why the sides 56a, 56b and the sides 38a, 38b defined by the intermediate wall 36 essentially correspond to each other. The arrangement of the openings becomes more obvious from
The individual successive mixer elements 42 are connected to one another by struts 56, with the struts 56 also acting as further guide walls. The number of mixer elements 42 and the corresponding length of the struts 56 is selected in dependence on the kind of material that is to be dispensed with a certain static mixer 10. For some applications five mixer elements 42 may be sufficient whereas for others ten or more mixer elements 42 may need to be connected to one another by means of struts 56. An outer surface of the struts 56 has the same curvature as an inner surface of the mixer housing 12 and the struts 56 make direct contact to the mixer housing 12.
The cross-section according to
The separating wall 32 comprises two thickened segments 35 arranged at a periphery of the output surface 30. Both thickened segments 35 are followed by curved segments 34a which both extend to an edge of the outlet 28a. From here two linear segments 34b follow which both extend to an edge of the outlet 28b. The linear segments 34b are interconnected by a curved segment 34c which partly surrounds the outlet 28b. The outlets 28a, 28b hence are separated by the separating wall 32. The separating wall 32 in cooperation with the output surface 30, with the shoulder 13 (see
The flow obstruction 40a has a plane lenticular shape and partly overlaps with the outlet 28a (see also
Due to the meandering pattern of the separating wall 32 the components A, B when reaching the downstream edge 33 are arranged side by side in three partial flows or streaks in a plane perpendicular to the longitudinal axis AL. These three partial flows are indicated by arrows A1, B1, B2, wherein A1 corresponds to component A and B1, B2 correspond to component B. The partial flow A1 of component A is flanked by two partial flows B1, B2 of component B. After exceeding the downstream edge 33 of the separating wall 32 the three partial flows A1, B1, B2 combine (without becoming intermixed) and are transversely divided by the intermediate wall 36 such that six partial flows A11, A12, B11, B12, B21, B22 result which are indicated by six arrows pointing upwards out of the drawing's plane. A11, A12 represent the divided partial flow A1 of component A. B11, B12, B21, B22 represent the respectively divided partial flows B1 and B2 of component B. Three partial flows, i.e. A11, flanked by B12 and B22, are located on side 38a and three partial flows, i.e. A12 flanked by B11 and B21, are located on side 38b of the intermediate wall 36.
As regards side 38a of the intermediate wall 36, when proceeding further the partial flow A11 encounters the bottom edge 51 of the bottom section 50 of the first mixer element 42 (see
As regards the other side 38b of the intermediate wall 36, when proceeding further each of the two outer partial flows B11 and B21 encounter one of the lateral sections 52a, 52b (see
Thus, each opening 20a, 20b, 20c of the first mixer element 42 is fed with partial flows of both components A, B. Altogether, this results in seven alternating partial flows being fed into the entry openings 20a, 20b, 20c. The partial flows are split as follows among the openings 20a, 20b, 20c starting from opening 20a: B12, A11, B11, A12, B21, A11, B22. This leads to a high mixing level already emerging after the first mixer element 42 has been passed. Thereby the total number of successive mixer elements 42 can be kept small and the total length of the static mixer can thus be reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15192415 | Oct 2015 | EP | regional |
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| Number | Date | Country | |
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| 20170120206 A1 | May 2017 | US |
