APPARATUS AND METHOD FOR MIXING COMPONENTS

Abstract

A dynamic mixer comprises a mixing chamber having a plurality of inlets and an outlet as well as a mixing element rotatably arranged in the mixing chamber. The mixing takes place by a to and fro movement of the mixing element.

Claims

1. A dynamic mixer, comprising a mixing chamber having at least one first inlet and one second inlet and an outlet; a mixing element rotatably arranged about an axis of rotation in the mixing chamber, and at least one abutment that prevents a rotation of the mixing element by 360°, the dynamic mixer is integrated in a metering valve; and the volume of the mixing chamber and of a media channel from the outlet up to a valve seat of the metering valve has a volume of less than 350 mm.sup.3.

2. The mixer in accordance with claim 1, wherein the at least one abutment is arranged in the mixing chamber.

3. The mixer in accordance with claim 1, wherein the mixing element divides the mixing chamber, viewed in cross-section, into two mutually separate part chambers when it is not in one of its end positions.

4. The mixer in accordance with claim 1, further comprising a first radial gap that is provided between a radially outer end of the mixing element and a wall of the mixing chamber.

5. The mixer in accordance with claim 4, wherein the first radial gap extends in an axial direction.

6. The mixer in accordance with claim 1, further comprising a second radial gap that is provided between a shaft section of the mixing element and a wall of the mixing chamber.

7. The mixer in accordance with claim 6, wherein the second radial gap extends in an axial direction.

8. The mixer in accordance with claim 1, wherein the mixing element has a shaft section and at least one wiping vane arranged thereat.

9. The mixer in accordance with claim 8, wherein the wiping vane does not extend over the total axial length of the mixing chamber.

10. The mixer in accordance with claim 9, wherein the at least one wiping vane extends only over approximately 85%-99% of the length of the mixing chamber.

11. The mixer in accordance with claim 8, wherein the at least one wiping vane contacts the at least one abutment areally at least in an end position of the mixing element.

12. The mixer in accordance with claim 8, wherein the at least one wiping vane is partly interrupted.

13. The mixer in accordance with claim 1, wherein the mixing chamber has, viewed in cross-section, a cross-section differing from a circular shape over a part section of its periphery.

14. The mixer in accordance with claim 13, wherein the cross-section of the mixing chamber, viewed in cross-section, differs from the circular shape over its total axial length.

15. The mixer in accordance with claim 1, wherein the mixing chamber has a radius, viewed in cross-section, i.e. in a section perpendicular to the axis of rotation, that decreases from a maximum radius down to a minimal radius over a part section of the periphery of the mixing chamber and then increases in size again up to the maximum radius.

15. The mixer in accordance with claim 1, wherein the radius that decreases from a maximum radius down to a minimal radius over a part section of the periphery of the mixing chamber decreases over its total axial length and then increases in size again up to the maximum radius.

16. The mixer in accordance with claim 1, wherein the mixing chamber has, viewed in cross-section, i.e. in a section perpendicular to the axis of rotation, a peripheral contour that is continuous in the mathematical sense and that has two inflection points.

17. The mixer in accordance with claim 1, wherein the mixing chamber has a volume of less than 20 mm.sup.3.

18. (canceled)

19. A method for mixing two components, the method comprising the following steps: introducing a first component and a second component into a mixing chamber; and mixing the two components in the mixing chamber by a rotatable mixing element, wherein the mixing element is respectively moved to and fro up to an abutment provided in the mixing chamber.

20. The method in accordance with claim 19, wherein the method is carried out in a mixer, the mixer comprising the mixing chamber having at least one first inlet and one second inlet and an outlet; the mixing element rotatably arranged about an axis of rotation in the mixing chamber, and the abutment that is configured to prevent a rotation of the mixing element by 360°.

21. The method in accordance with claim 19, further comprising the step of: urging the two components with the aid of the mixing element on each to and fro movement in opposite directions through at least one radial gap.

22. The method in accordance with claim 21, wherein the at least one radial gap extends in an axial direction and is provided between the mixing chamber and the mixing element.

Description

[0018] The present invention will be described in the following purely by way of example with reference to an advantageous embodiment and to the enclosed drawings. There are shown:

[0019] FIG. 1 a perspective view through a dynamic mixer that is integrated into a housing of a metering valve;

[0020] FIG. 2 a longitudinal section through the arrangement of FIG. 1;

[0021] FIG. 3 a plan view of the arrangement of FIG. 1;

[0022] FIG. 4 a section along the line IV-IV of FIG. 2; and

[0023] FIG. 5 a sectional view comparable with FIG. 4, but with the mixing element having been rotated counter-clockwise in the direction of the abutment.

[0024] FIG. 1 shows a housing 10 of a metering valve that is not shown in any more detail and that is integrated into a dynamic mixer whose outlet 12 is in communication with the metering valve (not shown) via a media channel 14. The housing 10 of the metering valve thus also forms the housing of the dynamic mixer and a mixing chamber 16 whose cross-section can be easily recognized in FIGS. 4 and 5 is provided in the housing 10. The mixing chamber 16 has a first inlet 18 and a second inlet 20 into which inlets a first inlet passage 18′ and a second inlet passage 20′ open for supplying two fluid components of the medium to be mixed. It is understood that more than two inlets or also more than one outlet can also be provided.

[0025] A mixing element 22 that is rotatable in the mixing chamber via a shaft 24 that is guided in a socket 26 screwed in the housing 10 is provided in the mixing chamber 16 for an intimate blending of the components to be mixed in a small volume and in a short time.

[0026] The mixing element 22 comprises a cylindrical shaft section 28 that has a somewhat smaller diameter than a shaft section of the shaft 24 located in the socket 26 and that extends over the total length of the mixing chamber 16. A wiping vane 30 is molded at or fastened to the outer periphery of the shaft section 28; it extends over approximately 90% of the axial length of the mixing chamber 16 and its radially outer end forms a radial gap A1 extending in the axial direction with the wall of the mixing chamber (16).

[0027] The wiping vane 30 in the embodiment shown is continuous in the longitudinal direction, i.e. it is not interrupted, and it is connected to the shaft section 28 such hat no sharp edges are formed. The wiping vane 30 has a uniformly convexly curved surface at its radially outer jacket surface such that the medium can flow evenly through the radial gap A1.

[0028] The cross-sectional views of FIGS. 4 and 5 illustrate that the mixing chamber 16 is not circularly symmetrical, but rather has, viewed in cross-section, a cross-section differing from the circular shape over a part section of its periphery (at the bottom in the Figures) over its total axial length in the embodiment shown (cf. FIG. 2). In more precise terms, the mixing chamber 16 has, viewed in cross-section, a radius (whose center is intersected in a perpendicular manner by the axis of rotation of the shaft 24) that reduces from a maximum radius down to a minimal radius over a part section of the periphery of the mixing chamber and over its total axial length and then increases in size again up to the maximum radius, with the part section of the periphery extending over approximately 90°. The mixing chamber 16 thus has, viewed in cross-section, a peripheral contour or a surface line that is continuous in the geometrical sense and that has two inflection points, whereby an abutment 32 is formed within the mixing chamber 16 that is integrated into the wall of the mixing chamber and that prevents a rotation of the mixing element 22 by a complete 360°. In this respect, a second radial gap A2 is formed between the abutment 32 and the shaft section 28 of the mixing element 22 (cf. FIG. 2 and FIG. 5); it extends in the axial direction and the wiping vane 30 can urge medium through it when the mixing element 22 moves to and fro.

[0029] As FIGS. 4 and 5 illustrate, the mixing element 22 divides the mixing chamber 16, viewed in cross-section, into two mutually separate part chambers 16a and 16b when the mixing element 22 is not in one of its two end positions. In this respect, the volume of the two part chambers 16a and 16b is the same when the mixing element 22 is in the middle position shown in FIG. 4. At the same time, the volume of the respective part chamber can be reduced to zero or almost zero when the mixing element 22 is in one of its two end positions. In this end position, the wiping vane 30 of the mixing element 22 contacts the abutment 32 areally and over the total axial length of the wiping vane 30 such that the medium that was previously located in the part chamber 16a (or 16b) has been completely urged through the radial gap A2 into the respective other part chamber. If therefore, for example, the mixing element 22 is in its left end position (it is close to that position shown in FIG. 5) and if the mixing element is subsequently rotated clockwise, the medium located in the maximized part chamber 16b is urged both through the radial gap A1 and through the radial gap A2 into the opening chamber 16a and is mixed in so doing.

[0030] A method for mixing two components can be carried out using the above-described dynamic mixer in which a first component and a second component are introduced through the inlet channels 18′ and 20′ into the inlet 18 and the inlet 20 of the mixing chamber 16 in that the components are pressurized. The two components are then mixed in the mixing chamber 16 by the rotatable mixing element 22 in that the mixing element 22 is respectively moved to and fro up to the abutment 32 provided in the chamber 16. The two components introduced into the mixing chamber 16 or the medium located in the mixing chamber 16 are urged with the aid of the mixing element on each to and fro movement of the mixing element 22 in opposite directions through the first radial gap A1 and through the second radial gap A2 that is respectively provided between the mixing chamber and the mixing element. The to and fro movement of the mixing element 22 takes place in this respect in the embodiment shown over approximately 270°, i.e. the direction of rotation of the mixing element is constantly changed.

[0031] On a use of a divided mixing element or of a mixing element having interruptions, a greater turbulence can provide a greater intermixing, whereas the embodiment shown having a continuous wiping vane provides a particularly uniform wiping of the medium.

[0032] The drive of the mixing element can take place by a stepper motor with which the movement of the mixing element can be controlled very exactly with a changing direction of rotation. A recognition of the abutting or also of the approach to or toward the abutment can be recognized by the detection of the power consumption of the motor. It can hereby simultaneously be recognized if already hardened material has accumulated at the abutment at the housing wall. Such an increase namely produces a reduced angle of rotation that can be detected, in particular by the control of the motor. The zero position of the mixing element can furthermore be simply traveled to by the abutment. For this purpose, the motor is either moved on by a defined number of steps that is larger by at least one step than the maximum angle of rotation of the mixing element or the motor is traveled so far until an abutment is recognized with reference to the power load.

[0033] Alternatively, a simple electric motor can also be used for the drive and/or a distance sensor can be used that recognizes the end position or the abutment of the mixing element or measures the rotational movement of the rotor axis.

[0034] The above-described dynamic mixer is very well-suited for very small mixing volumes and only amounts to approximately 7 mm.sup.3 in the embodiment shown, which amounts to a little less than 4% of the mixing volume of static mixers. The volume of the mixed medium from the inlet up to a valve seat of the metering valve (including the media channel 14) can also be kept extremely small, for example below 300 mm.sup.3.