EP4204132A1

EP4204132A1 - Rotational mixing machine

Info

Publication number: EP4204132A1
Application number: EP20761567.5A
Authority: EP
Inventors: Steffen KÄMMERER; Georg Schneider
Original assignee: BHS Sonthofen GmbH
Current assignee: BHS Sonthofen GmbH
Priority date: 2020-08-25
Filing date: 2020-08-25
Publication date: 2023-07-05
Also published as: CN115666772A; WO2022042823A1

Abstract

A rotational mixing machine (10), comprising a housing (12) in which at least drive shaft (14, 16) is extending in a longitudinal direction, wherein an end portion of the drive shaft (14, 16) passes through a housing wall in the longitudinal direction, wherein the end portion of the drive shaft (14, 16) extending through the housing (12) is coupled rotationally fixed and axially movable to a drive unit (20, 21) adapted to drive at least the drive shaft (14, 16), wherein the drive unit (20, 21) is mounted to the housing (12) via elastic elements and/ or damping elements such that the drive unit (20, 21) is capable of moving at least in the longitudinal direction relative to the respective drive shaft (14, 16).

Description

Rotational mixing machine

Description

The present invention refers to a rotational mixing machine, comprising a housing of the mixing machine in which at least one mixing element is rotatably mounted on a corresponding drive shaft that is extending inside the housing in a longitudinal direction of the housing, wherein an end portion of the drive shaft passes through a housing wall in the longitudinal direction.

When filling and operating rotational mixing machines, for example in a production process for concrete parts, large impact forces may occur acting onto the mixing elements and onto the corresponding drive shaft(s). Due to the statically overdetermined bearing of the drive shaft and the attached transmission of known rotational mixing machines, these impact forces may introduce constraining forces into the system. So, an overstressing of the according components occurs which, in turn, may reduce the lifetime of these components and/or of the whole mixing machine such that an earlier maintenance or replacement becomes necessary.

It is, therefore, the object of the present invention to provide a rotational mixing machine that is capable of reducing the effect of occurring impact forces and, thus, may increase the lifetime of respective components of the mixing machine.

The above object is solved according to the present invention by a rotational mixing machine, comprising a housing of the mixing machine in which at least one mixing element is rotatably mounted on a corresponding drive shaft that is extending inside the housing in a longitudinal direction of the housing, wherein an end portion of the drive shaft passes through a housing wall in the longitudinal direction, wherein the end portion of the drive shaft extending through the housing is coupled rotationally fixed and axially movable to a drive unit adapted to drive at least the drive shaft, wherein the drive unit is mounted to the housing via elastic elements and/or damping elements such that the drive unit is capable of moving at least in the longitudinal direction relative to the respective drive shaft.

Due to this floating suspension of the drive unit on the drive shaft as well as on the housing, not only an axial displacement of the drive unit relative to the drive shaft but also a displacement of the drive unit relative to the housing can be supported or, respectively, accordingly acting forces may be sustained and absorbed.

When goods are filled into the housing of the mixing machine, a bending moment may occur on the drive shaft that tends to displace the drive shaft laterally (i.e. orthogonally to the longitudinal axis of the drive shaft). Because of the bearing of the drive shaft on the housing, the lateral bending of the drive shaft results in a counter-acting sideward movement of the end portion of the drive shaft outside of the housing. For example, if goods are filled into the housing and onto the drive shaft, the drive shaft is bent downwards, wherein the largest displacement occurs in the middle of the drive shaft between its two bearing points at which the drive shaft is rotationally supported on the housing. Consequently, the portion extending outside of the housing is displaced in the opposite direction, i.e. when the middle of the drive shaft in the housing is bent downwards, the end portion is tilted upwards having its pivot point in the bearing of the drive shaft on the housing. In particular, if the drive unit may be suspended by multiple elastic elements, also the bending displacement of the end portion may be sustained and absorbed because the drive unit may follow this bending movement.

The drive unit, preferably the transmission of the drive unit, may be connected to the end portion of the drive shaft via a keyed connection such as a spline shaft or an involute toothing. In particular, the drive unit may be supported by at least three elastic and/or damping elements that are circumferentially distributed, in particular substantially equally, around the longitudinal axis of the drive shaft. The elastic and/or damping elements may extend in the longitudinal axis of the drive shaft and may be hinged to the housing and/or the drive unit to allow a radial movement (with respect to the longitudinal drive shaft axis) of the drive unit relative to the housing. The elastic element may be a coil spring. The hinges may, each separately or taken in combination, form a cardan joint between the drive unit and the housing.

In an embodiment of the present invention, the force of gravity acting on the drive unit due to the drive unit’s weight may be completely supported by the end portion of the drive shaft. That is, a bearing that supports the drive shaft may also support the weight of the attached drive unit. So, no additional suspension supporting the weight of the drive unit has to be provided on the housing that may constrict a free movement of the drive unit relatively to the housing.

The drive unit may comprise a motor, preferably an electric motor, and a transmission, wherein the transmission has an input side coupled to the motor and an output side coupled to the end portion of the drive shaft. For example, the motor may be disposed above the transmission.

The motor and the input side of the transmission may be coupled by a belt, wherein the motor may be attached to a first base and the transmission may be attached to a second base, wherein the first base and the second base may be connected such that the first base and the second base are pivotable relative to each other, wherein a pivoting movement of the first base and the second base relative to each other increases or decreases a belt tension of the corresponding belt. To do so, the pivot axis between the first and second base may be spaced apart from rotational axes of pulleys that guide the belt. Furthermore, the second base may also be connected to the elastic elements and/or damping elements. It may be advantageous to provide an adjustment mechanism, preferably a screw mechanism that is configured to adjust and fix a relative orientation between the first base and the second base. By actuating the adjustment mechanism, and changing the relative orientation between the first base and the second base, the belt is tightened or untightened. Using a screw mechanism, the screw mechanism may be attached at one end to the first base and on the other end to the second base, wherein a turning of a screw may lengthen or shorten the screw mechanism to adjust the relative orientation between the first base and the second base. Also, a counter screw for locking the adjustment mechanism in a desired position may be provided.

In an embodiment of the present invention, the rotational mixing machine may comprise two drive shafts each equipped with mixing elements. Preferably, the two drive shafts are configured to rotate in a mutually opposite sense to enhance a mixing effect.

Furthermore, the two drive shafts may extend parallel to each other. This may further improve the mixing effect in the housing of the mixing machine.

Each of the two drive shafts may have an end portion passing through the housing wall in the longitudinal direction, wherein each end portion is coupled rotationally fixed and axially movable to an associated drive unit, wherein each drive unit is adapted to drive one single corresponding drive shaft. In other words, each drive shaft is driven by its own drive unit. Therefore, the above-mentioned with respect to the one drive shaft is equally applicable to the second drive shaft. Of course, also more than two drive shafts may be provided and the above-mentioned applies for the further drive shafts as well.

The two drive units may each comprise a motor and a transmission, wherein the two motors and/or the two transmissions are synchronized using a synchronizer unit such as a gear synchronizer or an elastic coupling. Especially, when the two drive shafts are equipped with mixing elements that are attached on one drive shaft and reach close to the other drive shaft or even mesh with another, it is important that the drive shafts are rotating in a synchronized manner to avoid damage or jamming of the mixing elements.

Here, each motor may be coupled to the synchronizer unit by a belt and, preferably, the synchronizer unit is coupled to the two transmissions, which are in rotational engagement with the corresponding drive shafts, by a bevel gear and a planetary gear. It is understood, that in case that the motor is coupled to the synchronizer unit by a belt, no belt between the motor and the transmission may be provided. It shall be mentioned at this point that the term “belt” herein is not restricted to a single belt but may comprise a plurality of belts such as a V-belt and/or a ripped drive belt.

Advantageously, the drive unit may be supported on the housing against rotational movement about the longitudinal axis of a corresponding drive shaft by a torsional support. This may reduce rotational stress introduced into the elastic elements and/or damping elements and the according hinged connections, respectively.

The torsional support may be attached on its one side to the housing and on its other side to a base supporting the part of the drive unit being attached to the corresponding drive shaft. This base supporting the part of the drive unit may be preferably the second base supporting the transmission of the drive unit.

The torsional support may comprise an elastic element configured to reduce stress transferred from the drive unit via the torsional support into the housing. For example, on each attachment side of the torsional support, a rubber eyelet may be provided that reduces or even absorbs initial stress introduced into the torsional support, e.g. when starting the mixing machine. In the following, the present invention is explained in greater detail using a specific embodiment with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of an embodiment of the rotational mixing machine according to the present invention;

Figure 2 shows a sectional top view of the mixing machine of Fig. 1 taken along the line ll-ll of Fig. 5;

Figure 3 shows a detail of the mixing machine in a side view;

Figure 4 schematically shows a displacement movement of a drive shaft of the mixing machine of Fig. 1 ; and

Figure 5 shows a front view of the mixing machine.

In Fig. 1 , a rotational mixing machine according to the present invention is generally denoted with the reference numeral 10. The mixing machine 10 comprises a housing 12 into which components, for example components for mixing concrete, can be filled from the top that are to be mixed by the mixing machine 10.

In this embodiment, two drive shafts 14 and 16 are arranged inside the housing 12 (see Fig. 2) which run in parallel in a horizontal longitudinal direction A, and in Fig. 2 from left to right. Each of the drive shafts 14, 16 is equipped with a plurality of mixing elements 18 that are configured to perform a mixing action as if a plurality of shovels are mixing the components.

Furthermore, Fig. 1 shows that outside the housing 12 two drive units 20, 21 are disposed, one for each drive shaft 14, 16. The two drive units 20, 21 here each comprise a motor 22, 23, which are in this embodiment electric motors 22, 23, wherein each motor 22, 23 drives a belt 24, 26 by rotating a drive pulley 28, 30. The belts 24, 26 are wound over one of the drive pulley 28, 30 and over a respective driven pulley 32, 34 being driven by the belt 24, 26. The driven pulleys 32, 34 are then each connected to an associated transmission 36, 38 being part of the drive units 20, 21 that is configured to drive the corresponding drive shaft 14, 16.

In-between the two driven pulleys 32, 34 a synchronizer unit 40 is disposed (see also Fig. 3) that is adapted to synchronize the rotational movement of the two driven pulleys 32, 34. Doing so, for example, even if the motors 22, 23 may drive the drive pulleys 28, 30 at slightly different actuation speeds, it can be ensured that the two drive shafts 14, 16 rotate in a synchronous manner. As can be seen in Fig. 2, the mixing elements 18 (only some of them are shown) reach from the drive shaft 14 or 16 that they are attached to over the middle towards the other drive shaft 16 or 14. Hence, the synchronized rotational movement of the drive shafts 14, 16 synchronized by the synchronizer unit 40, ensures that the mixing elements 18 may not come into contact with each other or even damage one another.

Now, referring to Fig. 2, each drive shaft 14, 16 comprises an end portion 42, 44 that passes through a housing wall 46 of the housing 12. The drive shafts 14, 16 are supported in the housing wall 46 by bearings 50, 51 and are also supported in an opposite housing wall 48 on the opposite longitudinal end of the drive shafts 14, 16 by bearings 52, 53.

The end portions 42, 44 are connected to the transmissions 36, 38 via keyed connections such as an involute toothing. Thus, the transmissions 36, 38 are merely slipped onto the end portions 42, 44 such that the connection between the transmissions 36, 38 and the end portions 42, 44 is adapted to transfer rotational forces (torques) but not to transfer axial forces. In other words, a relative axial movement in the longitudinal direction of the drive shafts between the transmissions 36, 38 and the end portions 42, 44 is allowed.

Figure 3 shows a side view of the area of the rotational mixing machine 10 in which the drive unit 20 is mounted. Here, the motor 22 is mounted on a first base 54 above the transmission 36. The transmission 36 is mounted on a second base 56. The first base 54 and the second base 56 are mutually articulated by the hinge 58. By adjusting the relative orientation of the first base 54 to the second base 56, the distance between the drive pulley 28 and the driven pulley 32 can be changed. Doing so, the tension of the belt 24 is changed such that the belt 24 may be tightened or untightened, as desired.

In order to adjust the relative orientation of the first base 54 and the second base 56 in a simple and reliable manner, a screw mechanism 60 is provided acting between the first base 54 and the second base 56. By operating the screw mechanism 60, the first base 54 is tilted relative to the second base 56 such that the belt tension is adjusted. It is to be understood that the description given for the drive unit 20 and/or the drive shaft 14 and/or the first/second base 54, 56 etc. may also apply to the other drive unit 21 .

The drive unit 20, i.e. the second base 56 in the shown embodiment, is supported on the housing via elastic elements 62. The elastic elements 62 each comprise a rod 64 that is pivotably hinged to the housing 12 of the mixing machine 10 on its one end. The other end of the rod 64 passes through the second base 56, wherein a compression spring 66 is disposed between the free end of the rod 64 and the second base 56 such that the spring 66 biases the second base 56 in the direction of the housing 12. In the embodiment shown, each of the drive units 20, 21 is supported by three elastic elements 62. Additionally, there may be provided a damping element that is adapted to dampen a swinging movement of the second base 56.

Now, when the drive shaft 14, and consequently the end portion 42, is displaced from its position shown in Fig. 2, irrespectively if displaced axially along the longitudinal axis A of the drive shaft 14 or displaced laterally resulting in a bending movement (see Fig. 4), the drive unit 20 may follow this displacement due to the floating suspension of the drive unit 20 on the drive shaft 14 and on the housing 12 via the elastic elements 62. Since the motor 22, the drive pulley 28, the belt 24, the driven pulley 32 and the transmission 36 are all supported on the second base 56 or the attached first base 54, respectively, a displacement of the second base 56 does not result in a variation of the tension of the belt 24. The synchronizer unit 40 in this embodiment is provided with rubber elements that are adapted to compensate a displacement of the drive unit 20 relative to the drive unit 21 without imparting the functionality of the synchronizer unit 40.

In Fig. 4, a possible displacement movement of the drive shaft 14 is shown schematically in a side view, which is similar to the viewing direction in Fig. 3. When force is applied onto the drive shaft 14, e.g. by placing heavy goods onto the drive shaft 14, the drive shaft 14 is bent downwards (as shown by the arrow L) from its straight arrangement (indicated by the dotted line A). Because of the bearing support of the drive shaft 14 in the housing walls 46, 48, the displacement of the drive shaft 14 towards the bottom of the housing 12 results in an upward tilting movement of the end portion 42 (as shown by the curved arrow in Fig. 4).

In turn, the tilting movement of the end portion 42 results in a tilting movement of the transmission 36, i.e. of the drive unit 20. Referring to Figs. 3 and 5, it becomes clear that this tilting movement of the drive unit 20 is absorbed by the elastic elements 62 such that the springs 66 of the lower two elastic elements 62 are compressed and/or the spring 66 of the upper elastic element 62 is stretched (compared to the position shown in Fig. 3). Furthermore, the rods 64 may follow this displacement based on their articulated arrangement on the housing 12. As a result, a displacement of the drive shafts 14, 16 may not transfer stress into a support of the drive units 20, 21 on the housing 12 and/or may not change a predetermined tension of the belts 24, 26.

As it is shown in Fig. 5, the second base 56 may be provided with an extension 68 extending in a substantially radial direction with respect to the longitudinal axis A of the corresponding drive shaft 14, 16. The extension 68 is connected to a first end of a turnbuckle 70 that is attached to the housing 12 on its second end. The turnbuckle 70 is adapted to support the drive unit 20 against rotational forces acting circumferentially about the longitudinal axis A of the corresponding drive shaft 14. By turning the turnbuckle 70, a rotational orientation of the drive unit 20 relative to the housing 12 can be adjusted.

The turnbuckle 70 is pivotably movable on its both ends such to not restrict the functionality of the floating suspension of the drive unit 20. Additionally, damping elements 72 are provided at the pivotable connection of both ends of the turnbuckle 70 to reduce shock forces introduced from the drive unit 20 into the turnbuckle 70 and into the housing 12. The damping elements 72 are formed as eyelets of the turnbuckle 70.

Claims

Claims Rotational mixing machine (10), comprising a housing (12) of the mixing machine (10) in which at least one mixing element (18) is rotatably mounted on a corresponding drive shaft (14, 16) that is extending inside the housing (12) in a longitudinal direction (A) of the housing (12), wherein an end portion (42, 44) of the drive shaft (14, 16) passes through a housing wall (46) in the longitudinal direction (A), wherein the end portion (42, 44) of the drive shaft (14, 16) extending through the housing (12) is coupled rotationally fixed and axially movable to a drive unit (20, 21 ) adapted to drive at least the drive shaft (14, 16), wherein the drive unit (20, 21 ) is mounted to the housing (12) via elastic elements (62) and/or damping elements such that the drive unit (20, 21 ) is capable of moving at least in the longitudinal direction (A) relative to the respective drive shaft (14, 16). Rotational mixing machine (10) according to the preceding claim, characterized in that the force of gravity acting on the drive unit (20, 21 ) due to the drive unit’s (20, 21) weight is completely supported by the end portion (42, 44) of the drive shaft (14, 16). Rotational mixing machine (10) according to any of the preceding claims, characterized in that the drive unit (20, 21 ) comprises a motor (22, 23), preferably an electric motor (22, 23), and a transmission (36, 38), wherein the transmission (36, 38) has an input side coupled to the motor (22, 23) and an output side coupled to the end portion (42, 44) of the drive shaft (14, 16). Rotational mixing machine (10) according to the preceding claim, characterized in that the motor (22, 23) and the input side of the transmission (36, 38) are coupled by a belt (24, 26), wherein the motor (22, 23) is attached to a first base (64) and the transmission (36, 38) is attached to a second base (56), wherein the first base (54) and the second base (56) are connected such that the first base (54) and the second base (56) are pivotable relative to each other, wherein a pivoting movement of the first base (54) and the second base (56) relative to each other increases or decreases a belt tension of the corresponding belt (24, 26). Rotational mixing machine (10) according to the preceding claim, characterized in that an adjustment mechanism (60), preferably a screw mechanism (60), is provided that is configured to adjust and fix a relative orientation between the first base (54) and the second base (56). Rotational mixing machine (10) according to any of the preceding claims, characterized in that the rotational mixing machine (10) comprises two drive shafts (14, 16) each equipped with mixing elements (18). Rotational mixing machine (10) according to the preceding claim, characterized in that the two drive shafts (14, 16) extend parallel to each other. Rotational mixing machine (10) according to claims 6 or 7, characterized in that each of the two drive shafts (14, 16) has an end portion (42, 44) passing through the housing wall (46) in the longitudinal direction (A), wherein each end portion (42, 44) is coupled rotationally fixed and axially movable to an associated drive unit (20, 21 ), wherein each drive unit (20, 21 ) is adapted to drive one single corresponding drive shaft (14, 16). Rotational mixing machine (10) according to the preceding claim, characterized in that the two drive units (20, 21 ) each comprise a motor (22, 23) and a transmission (36, 38), wherein the two motors (22, 23) and/or the two transmissions (36, 38) are synchronized using a synchronizer unit (40). Rotational mixing machine (10) according to the preceding claim, characterized in that each motor (22, 23) is coupled to the synchronizer unit (40) by a belt (24, 26) and, preferably, the synchronizer unit (40) is coupled to the two transmissions (36, 38), which are in rotational engagement with the corresponding drive shafts (14, 16), via a bevel gear and a planetary gear. Rotational mixing machine (10) according to any of the preceding claims, characterized in that the drive unit (20, 21 ) is supported on the housing (12) against rotational movement about the longitudinal axis (A) of a corresponding drive shaft (14, 16) by a torsional support (70). Rotational mixing machine (10) according to the preceding claim, characterized in that the torsional support (70) is attached on its one side to the housing (12) and on its other side to a base (56) supporting the part of the drive unit (20, 21 ) being attached to the corresponding drive shaft (14, 16). Rotational mixing machine (10) according to claim 11 or 12, characterized in that the torsional support (70) comprises an elastic element (72) configured to reduce stress transferred from the drive unit (20, 21 ) via the torsional support (70) into the housing (12).