FR2793166A1 - SPHERICAL MIXER - Google Patents

Abstract

The mixer has a transmission tube (70) mounted in rotation, a first axle (80) mounted in rotation inside the transmission tu and a second axle (76) mounted in rotation at the end of the transmission tube and supporting the mixing device (78). The second axle forms an angle alpha with the axis of the transmission tube and is driven in rotation about its own axis by the rotation the first axle. Preferred Features: The angle alpha is 45-90 degrees . The orientation of the mixing device can be varied relative to the second axle during its rotation and are in the form of segments of a circle. A first motor (66) drives the first axle and a seco motor (68) drives the transmission tube. The second axle is driven by the first axle via a gear. An Independent claim is also included for a mixing apparatus containing a mixer as above and a receiver (60) with a symmetr revolution described by the edge of the mixing device. The receiver has an outlet drain in its base.

Description

SPHERICAL MIXER

  The subject of the invention is a device for mixing and / or homogenization

of a heterogeneous medium.

  Mixers are used to mix several components. These can be gaseous, liquid or solid and miscible or immiscible. Mixing is an operation that occurs in all types of industry, which gives it a

considerable importance.

  "Mechanical unit operations", Course handout from E.N.S.I.C. 2nd Year of Christmas Midoux, 1989, describes mixers comprising a shaft on which are fixed mixing members. The organs can have various shapes, such as blades, propellers, anchors, screws or ribbons. The shaft is rotated by a drive means. The mixing elements of the mixer are immersed in a container containing the medium to be mixed. The speed of movement imparted to

  medium being variable in the medium, the mixture of the heterogeneous medium is obtained.

  The shaft can dive vertically into the container with the mixing members rotating horizontally, or it is introduced laterally into the container and the members rotate vertically. For some applications, the shaft can be tilted to rest on the edge of the tank. In all cases described in this

  document, the mixing elements rotate around the axis defined by the shaft.

  Mixers are also known which have two axes. Some household robots thus have a small tank. The rotational movement of the central shaft is then transmitted on the one hand to a second offset shaft so that it performs a planetary movement around the central shaft; the mixing members are mounted on the second shaft, and are thus rotated around this

  second tree at the same time as the tree describes a circle.

  The object of the invention is to improve the performance of existing mixers.

  Another object of the invention is to solve the new problem of dead zones in mixers. Indeed, if the mixer is not adapted to the geometry of the container, there are zones called dead zones, in which the medium remains at rest. In these areas, no mixing takes place. It is also possible that a mixed volume in such a dead zone will separate again. This problem is encountered in particular for the lower corners of cylindrical containers for example. This problem of dead zones and uniformity of the mixture is all the more sensitive when it is a question of mixing a viscous medium or mixing at low speed. In these cases, the effects of mixing are limited to the area swept by the mixing devices. A non-uniform mixture can then be obtained if the mixer is not adapted to the geometry of the container. The invention provides a

  solution to this dead zone problem.

  The mixer of the invention is also particularly suitable for mixing immiscible constituents having a different density; it makes it possible to avoid the separation of the constituents of the mixture under the effect of the difference in density of the constituents. The mixer of the invention is also suitable for mixing a medium

  comprising fragile constituents whose texture is desired to be preserved.

  The invention also makes it possible to mix in a container, while continuing the mixing or homogenization operation until the container is completely emptied. It avoids inadvertent incorporation of air into the mixture as well as splashes, which lead to fouling which can

  bring the appliance to a standstill for tedious cleaning.

  The invention applies to the mixture of media of any type, and in particular of viscous or pulverulent media. The mixer of the invention is particularly suitable for maintaining unstable mixtures, even in the presence of fragile components. Finally, the mixer according to the invention is particularly advantageous in that it can be adapted to the geometry of containers of various shapes. In addition, the mixer of the invention makes it possible to maintain the mixing or homogenization action until the container is completely emptied. It ensures a particularly soft mixture and also makes it possible to avoid splashes and incorporation

of air in the mixture.

  The invention provides a mixer, comprising a first shaft, a second shaft supported by the first shaft and rotating around it, a third shaft supported by the second shaft and substantially perpendicular to the first shaft, and

  mixing members rotating around the axis of the third shaft.

  Preferably, the mixing members rotate around a point on the third

  tree which is in the extension of the axis of the first tree.

  In one embodiment, the first shaft rotates the second

tree around the first tree.

  In another embodiment, the first shaft drives its own rotation

the second tree.

  It is advantageous that the second shaft drives the third in its own rotation

tree and mixing bodies.

  Preferably, adjacent mixing members have an orientation

  different from the third tree.

  In this case, the adjacent mixing members may have a

  orientation different from 45 compared to the third tree.

  In one embodiment, the mixing members have an orientation

  with respect to the third variable tree during rotation.

  Preferably, the mixing members have a shaped end edge

of segment of circle.

  The invention also provides a mixing device comprising such a mixer, and a container whose bottom has a symmetry of revolution and whose

  generator is the end edge of a mixing member.

  The container also preferably has a drain opening in the bottom. Other characteristics and advantages of the invention will appear on reading

  the following description of embodiments of the invention, given by way of example

  and with reference to the accompanying drawings which show: - Figure 1, a block diagram of a mixer according to the invention with its container; - Figure 2 a sectional view of a mixer according to a first embodiment of the invention; - Figure 3 a top view of the mixer of Figure 2; Figure 4 an enlarged view of a mixer according to another embodiment of the invention;

  - Figure 5 a view of yet another embodiment of the invention.

  The invention proposes, to improve the performance of known mixers, to arrange the rotating mixing members on a shaft which itself rotates in the medium, and which is oriented in a substantially horizontal direction. In this way, any dead zone in the container in which the mixing takes place is avoided, without however having a fixed point for the mixing members in the vicinity of the wall of the container. Figure 1 shows a block diagram of a mixer according to the invention. The mixer has a first substantially vertical shaft 1, which supports the mixing members, and which, as the arrow symbolizes, is driven in rotation. At its lower end, the shaft 1 supports a second shaft 2. In the embodiment of Figure 2, the shaft 2 is substantially vertical, and is offset from the first shaft. The second shaft 2 is rotated around the first shaft 1. The second shaft 2 carries at its lower end a third shaft 3 oriented in a substantially horizontal direction. The shaft 3 carries the mixing members, represented here in the form of blades 4 and 5. These blades are driven in rotation around the third shaft, and make it possible to mix the medium being

in container 6.

  In this way, in operation of the mixer of the invention, the mixing members are rotated around an axis substantially

  horizontal, this axis itself being rotated in the middle.

  Thus, the first shaft 1 is driven in rotation by drive means. The second shaft 2 is rotated around the first shaft 1, but also around itself. The second shaft 2 carries at its lower end a third substantially horizontal shaft 3 which carries the mixing members. The third shaft 3 is rotated, which leads to a rotation of the mixing members. The preferred embodiment provides for the drive of the three shafts by a single motor coupled to the shaft 1. However, it may also be advantageous to provide an independent drive for another or even all the shafts. If we also consider the satellite movement of the shaft 2 around the shaft 1, we see that the ends of the mixing members describe a sphere when the center of rotation of the mixing members coincides with the axis of l 'shaft 1 and a torus in cases where this center is offset from this axis. By center of rotation is meant the intersection between the axes of symmetry of the blades - if they exist - and the

third tree.

  As shown in the figure, the shape of the blades 4 and 5 can be adapted to the shape of the container, so as to minimize the dead zones in the container. Due to the rotation around the third substantially horizontal axis, there is no fixed point in the vicinity of the wall of the container. Due to the rotation of the second shaft around the third shaft, the third shaft is rotated in the container, and the axis of rotation of the mixing members rotates in the container. The bottom of the container according to the invention therefore has a symmetry of revolution around the axis of the first shaft - and its generatrix is the end edge of the mixing members; in the example, the bottom of the container is spherical, and the edge of the blades is an arc. In the embodiment of Figure 1, each of the mixing members is symmetrical with respect to a straight line. The intersection between this straight line and the tree 3 is

  found on the axis of the first tree 1, symbolized in the figure by a dotted line.

  This configuration is particularly advantageous in the case where the mixing members are driven in rotation on themselves, in addition to their rotation around

tree 3.

  It is also possible that the mixing members are not in the axis of the first shaft 1. This can in particular be advantageous for increasing the volume

  swept by the mixing bodies.

  Figure 2 shows a sectional view of a mixer according to a first embodiment of the invention; in the embodiment of Figure 2, the movement of the second shaft around the first, and the movement of the mixing members around the third shaft are provided by unique drive means; these unique drive means rotate the first shaft, which has the advantage that the drive means are not in motion during operation of the mixer. We find in Figure 2 the various elements already described with reference to Figure 1, and in particular the first shaft 1; this shaft is driven in rotation by drive means - for example of a variable speed gearmotor - not shown in the figure. At the lower part of the first shaft 1 is mounted for rotation a support 10, in which the second shaft 2 is mounted for rotation. The support 10 maintains the position of the second shaft relative to the first shaft, while

  by allowing the rotation of the second tree around the first tree.

  A first toothed wheel 11 is rotatably mounted around the first shaft, and is held fixed relative to the container 6 by a locking rod 12. In this way, the toothed wheel is fixed. A second gear 13 is fixed on the second shaft 2 and meshes on the first gear. The first and second gear wheels

form a first gear.

  A third gear 15 is fixed on the first shaft. A fourth gear 16 fixed on the second shaft meshes with the third gear. The

  third and fourth gears form a second gear.

  The assembly of the support 10, the first and second gears are arranged

in a housing 19.

  The operation of the elements which have just been described is as follows. The rotation of the first shaft 1 is transmitted to the second shaft 2 via the second gear; due to the first gear, the second shaft is rotated around the first shaft. The choice of the numbers of teeth from the first to fourth gearwheels enables the proper rotation speed of the second to be adjusted.

  tree, and the speed of rotation of the second tree around the first tree.

  On the lower side of the support 10 is fixed vertically a transmission tube 25 surrounding the second shaft 2. At the lower end of the transmission tube 25 is fixed a casing 40, in which the lower end of the second shaft is rotatably mounted . At the lower end of the second shaft is fixed a fifth toothed wheel27, with conical teeth. The third shaft 3 is rotatably mounted in the casing 40, and carries at its end a sixth toothed wheel 28, with conical teeth, which meshes on the fifth toothed wheel. The fifth and

  sixth gearwheels form a third gear.

  The blades 4 and 5 are fixed on the third shaft.

  In this way, the rotational movement of the support 10 rotates the housing 40 around the first shaft 1. The proper rotational movement of the second shaft 2 is transmitted to the third shaft 3 by the third gear, and drives the mixing members. The choice of the ratio of the numbers of teeth in the third gear makes it possible to adjust the proper rotational speeds of the second and third shafts. In the illustrated embodiment, the mixing members are mounted on rods 21 and 22, and are symmetrical with respect to the axis of these rods. The point of intersection of the rods and the third tree is on the axis of the first tree 1. The number and shape of the blades depends on the mixing problem to be solved. In the

  embodiment illustrated in Figures 2 and 3 are provided 4 blades.

  Advantageously, the orientation of the different blades can be adapted to the mixing problem; in particular, it is possible to vary this orientation with the angle

  of rotation, as explained with reference to Figure 4.

  Consequently, the mixing members perform both a vertical rotation movement, around the third shaft, which itself is driven by a horizontal rotation movement in the fluid. These movements lead, if the centers of these two rotations intersect, to a movement on a sphere of each of the points of the mixing members. According to the preferred embodiment, the center of rotation of the mixing members is located in the extension of the axis of the first shaft, and the ends of. It is also possible that the mixing elements

  are not in the extension of the shaft 2, but are offset horizontally.

  In this case, each point of a mixing member moves on a torus. According to an advantageous embodiment, the shape of the mixing members is adapted to the geometry of the bottom of the container used. Organs whose curvature of the ends corresponds to a segment of a circle are particularly advantageous. This allows optimal mixing efficiency to be obtained since the zones are avoided

  dead in containers with hemispherical bottoms or similar.

  Figure 3 shows a top view of the mixer of Figure 2. We recognize in Figure 3 the first shaft 1, the first gear 11 with the locking rod 12, the second gear 13, the third gear 15 and the fourth toothed wheel 16. The blades 4 and 5 are also seen in the figure, with the support rods 21 and 22. The arrows 31 and 32 indicate the rotation of the support 10 and of the third shaft around the first shaft. Arrows 33 and 34 indicate the rotations of the third and fourth toothed wheels 15 and 16. Arrows 35 and 36 indicate the rotation of the second toothed wheel, and the rotation of the second shaft around the

first tree.

  According to the preferred embodiment of Figures 2 and 3, the relative speed of rotation of the three shafts is fixed, and determined by the ratios of the different gears. It may however prove advantageous to provide means making it possible to vary these respective speeds. In this case, independent drive means can be provided for each of the shafts. Computer control of the different motors can also be advantageous, for example in the case where

  it is desired to vary the speeds during mixing or frequently.

  Figure 4 shows a detail of another embodiment, in which the device according to the invention further comprises a cam system making it possible to vary the orientation of the mixing members according to the angle of rotation of the third shaft. To this end, a fourth shaft 41 is provided inside the third shaft 3, which is fixed relative to the casing 40, as symbolized by the link 42 at the end of this fourth shaft. At its end remote from the casing, the fourth shaft has a wheel 44, with a raceway 45 on its perimeter which has

  an axial extension along the axis of the fourth shaft.

  In the embodiment of Figure 4, the blades are rotatably mounted on the third shaft; as shown in the figure, the rod 21 of the blade 4 is mounted at

  rotation in a radial bore 47 of the third shaft.

  At its end opposite to the blade, the rod 21 has an offset offset follower 49, which rolls in the raceway 45 of the wheel 44. The angular position of the rod 21 relative to the third shaft, and therefore the angular position of the blade 4 around

  the rod 21 depends on the position of the follower 49.

  The device of Figure 4 operates as follows. The rods 21 or 22 and the corresponding blades are rotated about the axis of the third shaft 3 by the rotation of the third shaft relative to the housing 40, due to the concomitant rotation of the bores in which the rods are mounted. During this rotation, the followers 49 roll in the raceway, and the fact that the raceway extends in different positions along the axis of the

  fourth shaft, vary the angular position of the rods, and therefore of the blades.

  The device of Figure 4 allows in this way to change the angle between the blades and the third shaft, during the rotation of the blades around the axis of the third shaft. A suitable raceway allows for example to enter the mixing members at an angle into the medium to be mixed and to bring them out in a knife, that is to say perpendicular to the surface, in order to minimize splashing and the incorporation of air. A variation of 45 between the angle between the plane of a mixing member and the third shaft on the one hand, and the angle between the plane of an adjacent mixing member and the third shaft on the other hand also constitutes an advantageous arrangement insofar as it causes a wave effect while

  by dragging the product with a bottom movement.

  Figure 5 shows yet another embodiment of the invention; in the embodiment of the invention, the assembly of the mixer and its container is mounted on two concentric cradles 51 and 52. The inner cradle supports the container and the mixer; the mixer support is not shown in the figure. The inner cradle is mounted on the outer cradle in rotation according to a common diameter of the inner and outer cradles; in the figure, this diameter is perpendicular to the plane of the sheet. The outer cradle is mounted for rotation on a support 53, for rotation along a diameter of the outer cradle perpendicular to the diameter on which the inner cradle is mounted. The assembly of the two cradles makes it possible to position the container and the mixer at any angle. The

  figure also shows the drain opening 54 located at the bottom of the container.

  In the embodiment of the figure, the two cradles are concentric at a point which is the intersection of the axes of the first and third shafts. We could

  also choose another fixed point for all the mixers.

  The assembly of FIG. 5 makes it possible to combine a movement of rotation of the container and of the mixer, with the movement of the mixing members. In this way, dead masses are avoided, and the deposit of mixed material on the walls of the

  container. This allows in particular to avoid the use of a scraper.

  The device of the invention is suitable for the rapid and efficient mixing of liquid or solid materials, for example powders. The results of mixing tests are given below in an apparatus of the type of that of FIGS. 2 and 3,

  for a mixture of saccharin in milk powder or in flour.

  In the first test, 100 g of saccharin and 8679 g were mixed. milk powder in the blender for 180 seconds. Then, three samples were taken from different areas of the mixing container and analyzed. The results of the tests are shown in Table 1 Saccharin (g) Milk powder (g)%

0.10 10.75 0.93

0.13 10.86 1.19

0.11 10.85 1.01

  These values are to be compared with the nominal percentage of 1.15% of saccharin in milk powder. They show that the mixture is very homogeneous

  after a short mixing time.

  In the second test, 100 g of saccharin and 10454 g were mixed. flour in the blender for 240 seconds. Then, three samples were taken from different areas of the mixing container and analyzed. The results of the tests are shown in Table 1 Saccharin (g) Flour (g)%

0.075 11.09 0.67

0.057 10.49 0.54

0.064 10.48 0.61

  These values are again to be compared with the nominal percentage of 0, 95% of saccharin in the flour. They are indicative of the separation of the constituents, which is achieved after a very short mixing time. It is indeed known that prolonged mixing can lead to separation of the initial constituents: such separation generally takes place after a very long mixing time.

greater than 240 seconds.

  The mixer of the invention has also proven to be particularly suitable for the manufacture of jams. Thus, it is frequently observed that at rest, the pieces of fruit, of lower density, rise to the surface of the mass of jam. It is then necessary to homogenize the mixture continuously during packaging in order to obtain a homogeneous final product, i.e. an equivalent quantity of pieces of fruit in each jar of jam. In the example cited, it is however desired to retain the texture of the pieces of fruit despite the mixing. It is therefore important that the mixing takes place in a delicate manner, without destroying the texture of the pieces of fruit, without incorporating air and without splashing. The mixer of the invention made it possible to obtain a great homogeneity of the distribution of the pieces of fruit,

  while preserving the texture of the pieces of fruit.

  Of course, the present invention is not limited to the examples and embodiments described and shown, but it is susceptible of numerous variants accessible to those skilled in the art. Likewise, it is clear that the invention is not limited to the preferred embodiment. In particular, in the embodiments described, the entire movement is transmitted to the different parts of the mixer, via the first shaft; this solution has the advantage of making it possible to mount the mixer drive motor in a fixed position, which limits the moving masses. One could also provide a first fixed shaft, and a motor driving the second shaft. In the embodiments described, the trees are perpendicular; one could also provide that the second tree is inclined relative to the first tree, for example to increase the volume capable of being swept

by the mixing devices.

Claims (11)

  1. Mixer, comprising a first shaft (1), a second shaft (2) supported by the first shaft (1) and rotating around it, a third shaft (3) supported by the second shaft (2) and substantially perpendicular to the first tree (1), and   mixing members (4, 5) rotating around the axis of the third shaft (3).   2. Mixer according to claim 1, characterized in that the mixing members rotate around a point of the third shaft which is in the   extension of the axis of the first shaft (1).   3. Mixer according to claim 1 or 2, characterized in that the first shaft   (1) rotates the second shaft (2) around the first shaft.   4. Mixer according to claim 1, 2 or 3, characterized in that the first   shaft (1) drives the second shaft (2) in proper rotation.   5. Mixer according to one of claims 1 to 4, characterized in that the second   shaft starts its own rotation of the third shaft and the mixing elements.   6. Mixer according to any one of claims 1 to 5, characterized in that   that adjacent mixing elements have a different orientation by compared to the third tree.   7. Mixer according to claim 5, characterized in that adjacent mixing members have an orientation different from 45 relative to the third tree.   8. Mixer according to any one of claims 1 to 7, characterized in that   the mixing members have an orientation relative to the third shaft variable during rotation.   9. Mixer according to any one of claims 1 to 8, characterized in that   that the mixing members have an end edge in the form of a segment of a circle. he 10. A mixing apparatus comprising a mixer according to any one of   claims 1 to 9, and a container whose bottom has a symmetry of revolution   and whose generator is the end edge of a mixing member.   11. The apparatus according to claim 10, characterized in that the container has a drain opening in the bottom.