WO1993004771A1

WO1993004771A1 - Static mixer

Info

Publication number: WO1993004771A1
Application number: PCT/EP1992/001955
Authority: WO
Inventors: Siegfried Riess; Holger Grossmann
Original assignee: Otto Tuchenhagen Gmbh & Co.Kg.
Priority date: 1991-09-03
Filing date: 1992-08-26
Publication date: 1993-03-18
Also published as: DE4129248A1; DE4129248C2

Abstract

A static mixer for mixing flowable substances within a tubular housing has at least two incorporated parts to be mounted in the housing. Each of these incorporated parts is made of a single piece, ribbon-shaped, and has a lamellar form of relatively small thickness. Each incorporated part is formed of a number n of active elements. The incorporated parts are interlaced or engage each other. The object of the invention is to create a static mixer that stands the comparison with state-of-the-art static mixers, as far as the mixing intensity of the continuous phase with the phase to be dispersed is concerned, as well as the attainable mass-transfer, but which has a lower pressure loss and a more simple structure, and is thus more economic to produce and easier to clean. For that purpose, in a first preferred embodiment of the disclosed static mixer, the active elements (1.1 to 1.n or 2.1 to 2.n) alternatively extend between opposite walls of the housing, each incorporated part (1, 2) extends in a plane (I or II), when it is mounted, and the planes in which the incorporated parts are located form an angle (β) with respect to each other. In another embodiment of the disclosed static mixer, at least three incorporated parts (1, 2, 3) are provided, the active elements (1.1 to 1.n; 2.1 to 2.n; 3.1 to 3.n) alternatively extend between a wall of the housing and a support element (6) arranged in or near the axis (A) of the housing, each incorporated part (1, 2, 3) extends in a separate plane (I or II or III), when it is mounted, and the planes in which the incorporated parts are located form an angle (β) with respect to each other.

Description

Static mixer

The invention relates to a static mixer for mixing flowable substances within a tubular housing, with at least two built-in parts in the housing, each of which is in one piece and band-shaped and has a lamellar shape of relatively small thickness and consists of a number A is formed by active elements, wherein the nutritional components are intertwined or intermeshed with one another.

In the case of static mixers of the gate identified at the beginning, when the fluids are pushed through the housing, not only are they roughly mixed, but also, owing to the strong shear stresses at the crossing points of the various partial flows, a more intensive local mixing.

From DE-PS 282 855 a related static mixer is known, which is designed as a double helix mixer and in which the double helix is formed from two interconnected strips of material, the strips of material each having guiding surfaces in the form of isosceles trapezoids, which - alternately and mirror-symmetrically offset around a main axis and connected to each other at their bevels - form folded edges. The longer of the two parallel trapezoidal sides, which is arranged opposite the shorter one - called the base - is each supplemented by an ellipse segment. The guiding surfaces of the mixing device are formed from the trapezoidal surfaces and ellipse segments each lying in one plane. An alternating change in the direction of folding that occurs around the folded edges creates winding angles that lie on both sides of the material strips, but have their apex inside the folded edges. A strand of the double spiral is made from two strips of material twisted in the same direction educated. The result is a spiral-type double-spiral mixer, in each case a base of trapezoidal surfaces of a strip of material coinciding with a folded edge of the second strip of material - and vice versa. The delimiting curves of the ellipse segments rest on the inner wall of the tubular housing. Hollow body-like, partially open and communicating with one another both in the axial and in the radial direction are formed between the adjacent guide surfaces, the axes of which diverge from the main axis of the device.

The guide surfaces guide the fluid flows in directions inclined to the housing axis and changing after short intervals, and the shear forces generated thereby break the disperse phase into small bubbles if the known static mixer is used, for example, for in-line gassing of liquids. The phase interface is continuously renewed by the bubbles coming together and forming new ones. Increased turbulence in the liquid promotes the mass transfer.

The shape of the internals in the known double-helix mixer results in a relatively large specific mixer surface in relation to the mixer volume, the two material strips having line contact with each other at each folded edge. The two strips form tapered spaces on these edges, which makes it difficult to clean them properly, particularly in these critical areas, particularly within systems of the food and beverage industry. Since the delimiting curves of the ellipse segments rest on the inner wall of the tubular housing, further cleaning-critical line contacts result here. The above-described design of the guide surfaces of the double helix and their arrangement within the bordering tubular housing form hollow-body-like, partially open mixing spaces, which promote the formation of a relatively high pressure loss when flowing through the static mixer. Furthermore the double helix represents an extremely complicated arrangement, with the cutting of the material strip already having a very complex contour and thus being able to be produced only with relatively great effort. In US-PS 40 40 256 a channel mixer is described in which the mixing elements consist of relatively simple, band-shaped, zig-zag-shaped installation parts. Here, two built-in parts are arranged one above the other in planes parallel to each other in the upwardly open channel parallel to the bottom part thereof. In addition to the fact that this known channel mixer cannot be used for intensive gassing of liquids, since this gas would escape due to the channel being open at the top, the known arrangement is also extremely unfriendly in terms of cleaning, since the built-in parts are parallel in one plane to the bottom of the channel are partially "capped" with an insert. This results in dead spaces that are insufficiently flowed through during cleaning.

The present invention has for its object to provide a static mixer of the type identified in the introduction, which compared with static mixers according to the prior art with regard to the intensity of the thorough mixing of the continuous phase with the phase to be dispersed and the achievable mass transfer withstands the technology, but has a lower pressure drop and a simpler and therefore more cost-effective and easy-to-clean design.

The object is achieved by applying the characterizing features of claim 1 or 11. Preferred embodiments of the static mixer are the subject of the subclaims.

The advantages of the proposed static mixer are, in particular, that the internals do not form any channels which have an adverse effect on the pressure drop, the circumferential contour of which is more or less self-contained, but that only active elements in the form of lamella surfaces are provided onto which the fluid flows partially collide and at which they are deflected. The effect of the relatively simple built-in parts corresponds amazingly to that of the known mixing elements without, however, having to accept the disadvantages mentioned above. For example, in the in-line gassing of water with air it was experimentally determined that a known static mixer (for example the Sulzer mixer, described in vt "procedural technology" 17 (1983) No. 12, pages 698 to 707) was approximately the same Enrichment of the water with oxygen (approx. 7 mg 02 / liter) has a pressure loss about twice as high as the proposed static mixer (1.3 versus 0.7 bar).

In addition, the static mixer according to the invention has the following flow properties:

homogeneous distribution of the phase to be dispersed in the pipe cross-section; - intensive mixing in the radial direction and thus uniform concentration in the entire pipe cross section; Gas to liquid volume flow can be varied within wide limits (ratio Qg / Ql <(5 to 10)).

The proposed static mixer is not only suitable for mixing fluid flows with one another, but in the most general case it can also be used to mix a continuous phase, a liquid or gaseous carrier fluid, with a disperse phase, which can be liquid, gaseous or solid.

The low pressure drop is essentially composed of two parts. The smaller proportion results from the fact that only the cross-sections of the active elements corresponding to the number of built-in parts are effective in a pipe cross-section, with a preferred embodiment of the static mixer according to the invention due to the very small lamella thicknesses sl and s2 and on- Because of the lamella widths b1 and b2, which are relatively small compared to the inner diameter of the tube D, there is an active element cross section which is approximately negligible in relation to the tube cross section. The greater part of the pressure loss is caused by the impact of the fluids on the fins and the subsequent deflection. The overall significantly lower pressure loss compared to the known static mixer under comparable conditions results from the. The fact that the proposed static mixer dispenses with a pressure loss-increasing division of the pipe flow into a large number of partial flows, each of which is bordered by a more or less self-contained channel.

A further advantageous embodiment of the static mixer according to the invention provides for the active elements of a built-in part to be designed to be flat and with an essentially uniform slat thickness and essentially each uniform width, with every second active element of a built-in part having the same inclination angle with the housing axis forms. The active elements expediently extend from one to the opposite housing wall in accordance with their chosen width. Distances between the built-in part and the adjacent housing walls are possible in principle; however, when viewed in the tube-axial direction, they increase the cross-sectional areas free of internals and generally reduce the intensity of the mixing. The zigzag-shaped course of the built-in parts given by the aforementioned configuration is very easy to manufacture. The Auεführung is simplified even further when the operative elements, as according to the invention provides for a different Auεgeεtaltung of the static mixer, εind magnitude supply angle inclined by the same inclination ^'against the Gehäuseachεe. The internals then have a congruent shape when viewed in their plane of extension.

If the housing axis of the static See mixer, for example, degassing phenomena due to gas bubble buoyancy occur when gassing liquids. The effects of this buoyancy are effectively countered by a further configuration of the static mixer, in which the built-in parts are arranged in the housing section in such a way that the vertical, the direction given by the gravitational field, halves the arrangement angle β.

According to a further proposal of the invention, the built-in parts can be arranged in a cylindrical tube, in a tube whose peripheral contour consists of a series of different radii of curvature, or in a tube with a regular or irregular polygonal cross-section.

An embodiment of the static mixer which is unsurpassed in terms of its simplicity is characterized in that in a cylindrical tube with the inside diameter d of the same size, built-in parts with the same slat thickness are provided, which are arranged at right angles to one another (arrangement angle β = 90 degrees ). The active elements, which are designed as flat surface elements and extend alternately between opposite tube walls, are inclined by the same angle α relative to the tube axis. This design results in built-in parts that are completely congruent with regard to each dimension. In the case of a cylindrical tube, this configuration results in a maximum width of the built-in parts, in which they just touch one another, but do not penetrate one another, and are to be inserted into the enveloping pipe as a package, interwoven with one another, as a package. With the above-mentioned special geometry of the built-in parts (ß = 90 degrees), their maximum width results in bmax = D / (5) ** l / 2. Even a slight reduction in the width of the built-in parts compared to the aforementioned maximum width ensures that the built-in parts no longer touch each other. The fact that this embodiment is particularly easy to clean is based on this fact.

In the proposed built-in parts according to the invention, the pressure loss in the static mixer increases quadratically with the width b, but only linearly with the length L of the built-in parts. On the other hand, for example, in the case of in-line gassing, the enrichment of the continuous phase with the gas phase to be dispersed increases in proportion to the width of the built-in parts with the same installation length, but with a degressive course. The design of the proposed static mixer is therefore an optimization task in each individual case. As a rule, the design of the static mixer with the maximum width bmax of the built-in parts is dispensed with and a longer length L of the built-in parts is accepted. A reduction in the width to a value b <bmax proves, as already mentioned above, to be advantageous with regard to the cleanability of the built-in parts within the pipe. As a result, you will find an association with one another in which, with the exception of the connection points at the beginning and at the end of their pipe-axial extension, there are no further contact or connection points which result in wedge-shaped gaps which are difficult to clean.

Due to their simple geometry, the built-in parts can expediently be produced by shaping, such as bending, folding, folding, forging, drop forging, stamping or deep-drawing, or by master forms, such as casting, investment casting or die casting. When forming, bending should be considered first, which is preferable for solid materials that allow a permanent (plastic) change in shape. In connection with this manufacturing process, thermoplastic plastic strips can also be mentioned, for example.

If the built-in parts made of shapeless materials such. B. liquid metals or thermosetting or thermoplastic plastics masses should be manufactured, so the original molds (casting) can also be used. Formed built-in parts can be interwoven with one another, as is provided, or else a width of the built-in parts with b> bmax is provided, in which they have to penetrate one another. In this case, they are connected to one another in the penetration areas; Such an embodiment is economically possible only through primary shapes, and, in contrast to embodiments with b <bmax, it has disadvantages in terms of cleaning technology.

According to a further proposal, it is provided that the built-in parts are made from preformed semifinished product, for example from corrugated or triangular or rectangular shaped sheets, in the course of a further forming process.

If, according to a further embodiment of the static mixer, the surface of the built-in parts is given a fine structure in the form of smooth elevations and depressions, for example by corrugation or knobs, which protrude from the laminar lower layer of the turbulent pipe flow, then this measure can be used the flow around the fins close to the wall with a view to a desirable turbulent cross-exchange and thus the cleaning effect of the cleaning fluid have a positive effect.

In order to reduce the cleaning-critical contact and connection points of the built-in parts to one another to a minimum, a further embodiment of the static mixer provides to connect the built-in parts only to one another at the beginning of their pipe-axial extension and to one another at the end and to the housing. The end connection of the built-in parts to the housing is necessary in order to fix the arrangement axially. Under the influence of the flow and pressure forces, the relatively ductile built-in parts are compressed in the direction of their pipe-axial extent against their end-side fastening point with the housing. Spread it they come to rest against the inner wall of the enveloping housing, thereby preventing further deformation. Temporary contact of the built-in parts with one another and vibrations of the mixer are avoided by this pressure, and due to the wall friction, the axial force on the mounting of the built-in parts is reduced.

In a further preferred embodiment of the proposed static mixer, the built-in parts are in engagement with one another, with at least three built-in parts being provided, the active elements of which are arranged alternately between a housing wall and one in or in the vicinity of the housing axis Extend support element. In the installed state, each built-in part is in each case arranged in a plane which forms an arrangement angle β with one another. This embodiment results in a shortening of the active elements, which now only extend between the essentially centrally arranged support element and the housing wall, with the result of an approximately doubling of the active element surfaces in relation to the length of the static mixer. Since the support element delimits each component on the one hand, there is no longer any interweaving of the components. In the area of the support element, the built-in parts are partially in engagement with one another.

In the case of an even number of built-in parts, according to an advantageous embodiment according to the invention, these can be arranged around the support element such that two built-in parts each extend in one plane, the two built-in parts assigned to one plane being separated from one another by the support element are. In the case of four built-in parts, the arrangement shown above results in an static mixer which, in its basic structure, is similar to that of the first embodiment, in which two built-in parts are provided, the active elements of which alternate between opposite housing walls extend. The difference between the two embodiments is that in the second embodiment, approximately twice the active element surface is installed, which was only possible by dividing the active elements by means of the support elements.

In order to reduce the cross-sectional areas of the housing part that are free of built-in parts in the housing axis, another embodiment of the static mixer according to the invention provides that a combination of built-in parts that are interwoven with one another or with one another in the housing and essentially parallel to the housing axis are engaged, is provided in a multiple arrangement. It can be a combination of built-in parts with or without a support element.

The proposed static mixer is described in more detail with reference to two exemplary embodiments in the figures of the drawing which follow. Show it

Figure 1 shows a particularly advantageous and extremely simple embodiment of the built-in parts according to the invention in a perspective view;

FIG. 2 shows a view of the built-in parts according to the detection in the direction of the tube axis, the vertical bisecting the arrangement angle β; FIGS. 3, 4 and 5 show the built-in parts according to FIG. 1 in the front, top and side views;

6, 7 and 8 show a further embodiment and arrangement of the built-in parts according to the invention in the front, top and side views, and FIG. 9 shows a static mixer with a combination of built-in parts according to the invention in a multiple arrangement within the housing. The built-in parts 1, 2 (FIG. 1) have a lamella-like shape. They are formed in one piece and consist of a number of planar active elements 1.1 to 2.1 or 2.1 to 2.n, the extension planes 1.11 of which are arranged at an arrangement angle of β = 90 degrees (cf. FIG. 2). The built-in parts 1, 2 are intertwined. In addition, FIG. 1 shows that the built-in parts 1 and 2 are congruent embodiments. This congruence is given by the same width, the respective angle of inclination of the active elements relative to the tube axis and the same lamella thickness.

FIG. 2 shows how the built-in parts 1, 2 are expediently positioned in the tube 5 or 5 * (tube 5 *, for example, formed as a square tube) when the tube axis A of the static mixer is not arranged vertically. It can be seen that the vertical S halves the arrangement angle β. In this case, the planar active elements of both built-in parts 1, 2 guide the fluid streams striking them predominantly in directions which have components in the direction of the vertical S. This counteracts a phase separation due to buoyancy. In the case of a horizontal arrangement of one of the two built-in parts 1 or 2, such a compensation would not be provided by this built-in part.

The congruent design of the built-in parts 1 and 2 is illustrated in FIGS. 3 to 5. Both from the front and from the top view it can be seen that the built-in parts 1 and 2 are formed from a number of n active elements (in the present case, the active elements 1.1 to 1.7 or 2.1 to 2.7) are formed. The latter are sl as a flat surface with elements of the lamellae thickness or s2 auεgebildet, wherein each εie ^'magnitude by the same Neigungεwinkel ß against the pipe achεe A are inclined. The congruence of the built-in parts 1 and 2 arises from the fact that the widths bl and b2 are the same in the illustrated embodiment. Furthermore, it can be seen from the side view (FIG. 5) that the extension planes I and II of the built-in parts 1 and 2 form an arrangement inke1β = 90 degrees. The length of an installation part 1, 2 is denoted by L, which inevitably results from the length 1 of an active element, measured in the direction of the tube axis A, and the number n of the active elements provided. Furthermore, it is clear from the three figures that the active elements extend in the form of a band and alternate between opposite pipe walls (inner diameter D) and pipe-axially. In the special exemplary embodiment shown (same width, same lamella thickness and same inclination angle α), the maximum possible width of the built-in parts 1, 2 is bmax = D / (5) ** l / 2.

As already explained above, this special design results in particularly simple and therefore inexpensive built-in parts 1, 2. The conditions underlying this special configuration (same width b, same slat thickness ε, same inclination angles 1 α) can, however, be dropped without further ado. The installation parts 1 and 2 can, as the names in FIGS. 3 to 5 make clear, with different widths b and b2 (also variable within one installation parts), different slat thicknesses εl and ε2 and different inclination angles αl *, αl * * or α2 *, α2 ** can be formed.

It has been shown in experiments that an angle deviating from the angle of inclination α = 45 degrees upwards or downwards has only an insignificant effect on the mass transfer or the mixing result. This suggests the conclusion that the actual length of the active element is less important than its length projected into the pipe cross-section. In the proposed embodiment, however, if the active elements extend from tube wall to tube wall, this is approximately the same as the inside diameter D of tube 5 and is therefore independent of the angle of inclination. For the choice of the angle of inclination β, it is less its influence on the material exchange or the mixing result than its effect decisive for the possibility of interweaving or joining the built-in parts 1, 2 and the pressure loss. With an angle substantially exceeding α = 45 degrees, the form-fitting interweaving of the built-in parts 1, 2 with one another is made considerably more difficult. An angle substantially below the inclination angle α = 45 degrees leads to an increase in the length L of the static mixer, which is generally undesirable. It has proven to be advantageous to carry out the angle of inclination α = 45 degrees, as illustrated in FIGS. 3 and 4.

The width bl = b2 = b of the built-in parts 1, 2 shown in FIGS. 3 to 5 corresponds to the maximum possible width bmax = D / (5) ** l / 2. The above-mentioned mathematical relationship results in an obvious manner from the geometry conditions on which the arrangement is based.

If the width b is considerably reduced compared to the maximum possible width bmax, it is also possible, for example, to arrange three built-in parts with the inner diameter D within the tube 5 under the conditions proposed according to the invention.

The built-in parts 1, 2 are connected to one another at the beginning B of their pipe-axial extension (FIG. 3, front view) and at the end C (FIG. 4, top view). At the end C there is also a connection to the tube 5.

FIGS. 6, 7 and 8 show the static mixer with a central support element 6 and four built-in parts 1 to 4. Each of these built-in parts extends with its assigned active elements 1.1 to ln or 2.1 to 2.n or 3.1 to 3.n or 4.1 to 4.n alternating between an inner wall of the housing 5 and the adjacent outer contour of the support element 6. The built-in parts are not intertwined with one another like those of the embodiment according to FIGS. 1 to 5, but they are in the area of the support element 6 partially engaged with each other. Regarding the Binding of the built-in parts 1 to 4 with one another and with the housing 5 applies analogously to what has already been done in this context in the embodiment according to FIGS. 1 to 5. Below a width at which the installation parts in question touch or even penetrate one another, their installation in the housing is completely independent of the width selection and is possible without difficulty, since there is no longer any interweaving of the installation parts in the sense of mutual penetration . The remaining reference symbols, which are not explained in more detail, can be explained from the relevant description of FIGS. 1 to 5.

FIG. 9 shows a static mixer in which a combination of built-in parts 1, 2 in a multiple arrangement (fourfold) is provided. The vertical S bisects the built-in parts 1, 2 ß the Anordnungswinke1, εo that Paral¬ lelität between the vertical S of Gehäusequerεchnitt ^'it and the respective vertical S of the combined built-in parts 1, is given. 2

In accordance with the preferred embodiments of the proposed static mixer described above, the active elements of an installation part are formed with a substantially uniform width. However, the invention is not intended to be limited solely to this geometric configuration. The invention is also intended to cover those configurations of the built-in parts in which the built-in parts each have a variable width. The change in width can take place continuously or discontinuously, with built-in parts that are interwoven or in engagement with one another can have an opposite change in width. The last-mentioned design makes it possible to produce built-in components that are variable in width from a strip of material of constant width.

Furthermore, the exemplary embodiments of the static mixer described above according to the invention fertilizer is restricted to such built-in parts, in which the fold edge of adjacent active elements is oriented at right angles to the direction in which the built-in parts extend within their plane. However, the invention is also intended to detect folds that deviate from the right angle mentioned above. This is possible without the direction of the extension of the built-in parts being left within their plane if the folding angle which deviates from the right angle changes alternately.

Claims

- 16 - Claims

1. Static mixer for mixing flowable substances within a tubular housing, with at least two built-in parts in the housing, each of which is in one piece and band-shaped and has a lamellar shape 5 of relatively small thickness and is formed from a number n of active elements is, the built-in parts being interwoven, characterized in that

- That the active elements (1.1 to l.n or 2.1 to 2.n) alternate between opposite housing

10 walls stretch,

- That each component (1, 2) extends in the installed state in one plane (I or II), and

- That the planes of the built-in parts form an arrangement angle β with one another.

15

2. Statiεeher Miεcher according to Anεpruch 1, characterized in that the active elements of a Ein¬ component (1, 2) flat and with a substantially respective lamella thickness (sl; ε2) and one in

20 essentially uniform widths (b1; b2) are formed, and that every second active element of a built-in part forms the same inclination angle (α1 *, αl **; α2 *, α2 **) with the housing axis (A) .

^'25

3. Static mixer according to claim 2, characterized in that each active element of the built-in parts (1, 2) is inclined in terms of amount by the same inclination angle (α) against the housing axis (A).

30 4. Static mixer according to one of claims 1 to 3, characterized in that when the housing axis (A) of the static mixer is not arranged vertically, the built-in parts (1, 2) are arranged in the housing cross section such that the vertical ( S) the arrangement angle

35 (ß) halved. 5. Static mixer according to one of claims 1 to 4, characterized in that the housing (5) is cylindrical, as a tube, its peripheral contour consists of a row of different radii of curvature, or as a tube with a regular or irregular polygonal cross-section.

6. Static mixer according to claim 3 or 4 and in training with a cylindrical tube with. the inner diameter (D), characterized in that the

Installation parts (1,2) with a width bl = b2 = b <bmax = D / (5) ** l / 2, the slat thickness with sl = s2 = s, the angle of inclination α = 45 degrees and the arrangement angle ß = 90 degrees are executed.

7. Static mixer according to one of claims 1 to 6, characterized in that the built-in parts (1, 2) are formed by shaping (such as bending, folding, folding, forging,

Die-forging, stamping, deep-drawing) or master forms (such as casting, investment casting, die casting) are produced.

8. Static Miεcher with formed by he built-in parts according to one of claims 1 to 6, characterized in that the built-in parts (1,2) are made of preformed semifinished product in corrugated or serrated Aus¬ design.

9. Static mixer according to one of claims 1 to 8, characterized in that the surface of the built-in parts (1, 2) has a fine structuring in the form of smooth elevations and depressions.

10. Static mixer according to one of claims 1 to 9, characterized in that the built-in parts (1, 2) are connected to one another at the start of their tubular axial extension and to one another and to the housing (5) at the end of their tubular axial extension.

11. Static mixer for mixing flowable substances within a tubular housing, with more than two built-in parts in the housing, each of which is in one piece and band-shaped and has a lamellar shape of relatively small thickness and one

n is formed by active elements, the built-in parts being in engagement with one another, characterized in that

- That at least three built-in parts (1, 2, 3) are provided,

- That the active elements (1.1 to ln; 2.1 to 2.n; 3.1 to 3.n) alternate between a housing wall and a support element (6) arranged in or in the vicinity of the housing axis (A), - that each Installation part (1, 2, 3) in the installed state extends in one plane (I or II or III), and

- That the levels of the built-in parts form an arrangement angle (β) with one another.

12. Static mixer according to claim 11, characterized in

- that an even number of built-in parts is provided, and - that two built-in parts each extend in one plane, the two built-in parts assigned to one plane being separated from one another by the support element (6).

13. Static mixer according to claim 11 or 12, characterized by the features of one or more claims of claims 2 to 10.

14. Static mixer using the built-in parts characterized in claims 1 to 13, characterized in that in the housing (5) and essentially parallel to the housing axis (A), a combination of built-in parts which are intertwined with one another or with one another are in engagement, provided in multiple arrangement.