Stirrer arrangement

Abstract

The invention relates to a stirrer arrangement (1) having a shaft (11), which can be driven rotatably about an axis of rotation (A), having a drive device (10), which is arranged at a first shaft end and is intended for driving the shaft (11), having a hub body (9), which is arranged at a second shaft end (12) for conjoint rotation with the shaft (11), and having at least two blades (7), which are arranged on the hub body (9) and extend substantially radially from the hub body (9), as seen in relation to the axis of rotation (A), wherein each of the blades (7) has a foot (13) for fastening on the hub body (9) and also, along the substantially radial extent, has a leading-edge region (14) and a trailing-edge region (15), which is located opposite the leading-edge region (14). According to the invention, the hub body (9) has a wall (17), in which depressions (19) for receiving the blade feet (13) are provided. Also provided, on the outer side of the wall (17), are set-back portions (26), which reach up to a sub-portion of the depressions (20), wherein, in the vicinity of the foot (13), each blade (7) has an extent which projects beyond the foot (13), is formed substantially by the leading-edge region (14) and projects into the respective set-back portion (26).

Description

[0001] The invention relates to an agitator arrangement comprising a shaft rotatably driven about an axis of rotation, a drive device arranged at a first shaft end for driving the shaft, a hub body arranged at a second shaft end in a rotationally fixed manner with the shaft, and at least two wings arranged on the hub body extending substantially radially from the hub body with respect to the axis of rotation, each wing having a foot for attachment to the hub body and, along its substantially radial extent, a leading edge region and a trailing edge region opposite the leading edge region.

[0002] These types of agitators, also known as flow accelerators, are used in many areas, for example, for the recirculation of activated sludge in aeration basins, for pumping rainwater, river water, surface water, and polder water, and for generating flow in bodies of water. The agitators are designed to achieve good flow control in the respective basins or systems in order to solve the specific process engineering task, such as thorough mixing of multiple phases.

[0003] The agitators are usually arranged on a freestanding agitator stand, as known from EP 2 328 676 A1, or fixed to a basin wall by means of a guide and support tube arrangement, as known, for example, from EP 2 659 959 A1.

[0004] DE 197 09 818 A1 also discloses a submersible mixer for liquids and slurries containing solids, according to the preamble of claim 1, with a housing that can be inserted into the medium to be stirred, in which a drive motor with a drive shaft projecting from the housing is arranged in a sealed manner, on which a propeller hub with at least two thrust propeller blades is attached, wherein each blade has a profile curved in the opposite direction of its forward rotation with a leading edge reinforced in cross-section, which is curved towards the thrust side, wherein the profile of each thrust propeller blade has a wide outer cut which terminates in a wide end section bent towards the suction side.

[0005] EP 2 689 831 A1 describes a stirring device arranged on a container cover.

[0006] Furthermore, agitator arrangements are known in which only the propeller with the shaft is arranged in the basin, while the drive is placed outside the basin, i.e., in the case of long-shaft agitators, in a horizontal or vertical installation position.

[0007] From EP 3 066 188 A1 a stirring device is known in which each stirring blade is attached to a receiving device, wherein several receiving devices form an axle receptacle into which a hub attached to the drive shaft is inserted and thus screwed.

[0008] Due to the separate manufacturing of the hub body and propeller blades, as described in EP 3 066 188 A1, a gap is created at the contact surface between the two components. Any dirt particles and fibers present in the flow can penetrate this gap and become lodged there. In particular, long fibers adhering to the rotating components in this area can negatively impact the performance and operational reliability of the agitator.

[0009] Particularly heavy soiling can ultimately necessitate unplanned maintenance or cleaning procedures, which are usually associated with downtime and therefore costs for the plant operator.

[0010] The present invention is based on the objective of mitigating or even completely eliminating the shortcomings of devices known from the prior art. Specifically, it is an objective of the present invention to provide an agitator arrangement in which the aforementioned fouling mechanisms are reduced and the efficiency is increased.

[0011] This problem is solved by an agitator according to claim 1, wherein the hub body has a wall in which recesses for receiving the wing feet are provided and recesses are provided on the outside of the wall which extend to a partial section of the recesses, wherein each wing has an extension near the foot extending beyond the foot, formed essentially by the leading edge region, which projects into the respective recess.

[0012] The recess is modeled after the leading edge contour of the propeller profile and, in conjunction with the three-dimensional leading edge design, allows dirt particles and fibers to slide off. The recess also generates secondary flows and turbulence, which prevent dirt from adhering in the gap area.

[0013] In an advantageous embodiment, the hub body comprises a substantially cup-shaped base body. This allows for very simple assembly and disassembly of the entire agitator, and, if necessary, of the individual blades.

[0014] To ensure that the interior of the hub body remains largely free of fibers, the hub body is closed at its free end with a lid.

[0015] Furthermore, for easy assembly and disassembly, the hub body includes a base element with a shaft receptacle into which the shaft can be inserted and connected to the hub body by means of a screw connection.

[0016] Furthermore, the base element is essentially conical, while the shaft receptacle is essentially cylindrical. The conical design of the base element significantly simplifies the assembly and disassembly of the wings, especially when the hub body is installed.

[0017] Further advantages, features and effects of the present invention will become apparent from the figures below. Fig. 1 a perspective view of the agitator according to the invention, Fig. 2 a longitudinal section through the hub body, Fig. 3 a perspective detail view of the hub body and Fig. 4 the hub body of the agitator according to the invention with blades attached to it.

[0018] The Fig. 1 Figure 1 shows an agitator arrangement 1 with an agitator stand 2, which in this embodiment is manufactured as a one-piece concrete or mineral casting component and has a base 3 and a receiving part 4. The contour of the receiving part 4 is designed such that it can accommodate a submersible motor agitator 5 and fix it in its working position.

[0019] The submersible motor mixer 5 has a stirring element 6, which here is designed as a propeller with 3 blades 7. A guide element 8 projects beyond the mixer stand 2, which is located in the Fig. 1 only partially shown. This guide element 8, which here is designed as a steel tube with a square cross-section, serves only to guide the submersible motor agitator 5 during lowering or raising.

[0020] The propeller or stirring element 6 comprises a hub body 9 on which the blades 7 are arranged.

[0021] The agitator 1 has a drive device 10 with a motor and gearbox (not shown in detail). A [missing information] in the Fig. 2 The shaft 11 shown is connected to the drive device via a first shaft end not shown and can be driven rotatably about a rotational axis A.

[0022] The Fig. 1 Figure 1 shows an agitator assembly 1 with an agitator stand 2, which is manufactured as a one-piece concrete or mineral casting component. However, the subject matter of the invention can also be used in agitator assemblies where only the propeller with the shaft is arranged in the basin, while the drive is located outside the basin.

[0023] As further from the longitudinal section showing the hub body 9 Fig. 2 As can be seen, the hub body 9 is arranged at a second shaft end 12 in a rotationally fixed manner with the shaft 11. At least two, in the Fig. 1 However, three blades 7, as shown, are arranged on the hub body 9 and extend substantially radially from the hub body 9 with respect to the axis of rotation A. Each of the blades 7 includes a base 13 for attachment to the hub body 9. The blades 7 have a leading edge region 14 and a trailing edge region 15 opposite the leading edge region 14 along their substantially radial extent. The agitator 6 rotates counterclockwise from the perspective of the drive device 10.

[0024] Again Fig. 2 As can be seen, the hub body 9 comprises an essentially cup-shaped base body 16 with a wall 17. The base body 16 or the wall 17 has a first body section 18 with a reduced inner diameter and a second body section 19 with an increased inner diameter.

[0025] In the first body section 18, the hub body 9, in particular the wall 17, has several recesses 20 corresponding to the number of wings 7. Each of the recesses 20 has a contact surface 21 against which the wing base 13, which is held in the recess, rests. The contact surfaces 21 are essentially parallel to the axis of rotation A. At the free end of the second body section 19, the hub body 9, in particular the cup-shaped base 16, can be closed with a lid 22.

[0026] The hub body, in particular the base body 16, comprises a base element 23 with a shaft receptacle 24 into which the shaft 11 can be inserted and connected to the hub body 9 by means of a screw connection. The base body 16 coaxially surrounds the shaft receptacle 24, via which the hub body 9 can be arranged or fastened to the shaft 11. The base element 23 is essentially conical, with the shaft receptacle 24, which is formed integrally with the base element 23, having an essentially cylindrical shape.

[0027] From the Fig. 3 It is evident that a plurality of through-holes 24 are provided in the area of ​​the recesses 20, extending from the mounting surface 21 into the interior of the hub body 9. The wings 7 are arranged or fastened to the base body 16 of the hub body 9 by means of connecting elements 25.

[0028] The fasteners 25 can, for example, include screws or threaded bolts with nuts. The screws or threaded bolts extend through the through holes 24 and are screwed into corresponding threaded holes (not shown) in the wing feet 13.

[0029] In the area of ​​the first body section 18, the hub body 9, in particular the base body 16, has a recess 26 on the outside of the wall 17, which extends to part of the depression 20. The recess 26 has a contact surface 27.

[0030] The Fig. 4 Figure 1 shows the side view of the hub body 9 with the wings 7 attached to it. Each of the wing feet 13 is recessed into one of the depressions 20. Near the foot 13, the wing 7 has an extension projecting beyond the foot 13, formed essentially by the leading edge region 14. The extension formed by the leading edge region 14 projects into the recess 26. Part of the leading edge region 14 comes into contact with the recess 20. Fig. 3 shown area 27 in the appendix.

Claims

1. Stirrer arrangement (1) having a shaft (11) which is drivable in rotation about a rotational axis (A), a drive device (10) which is arranged at a first shaft end for driving the shaft (11), a hub body (9) which is arranged rotationally fixedly on the shaft (11) at a second shaft end (12), at least two blades (7) which are arranged on the hub body (9) and extend substantially radially from the hub body (9) relative to the rotational axis (A), wherein each of the blades (7) has a foot (13) for fastening on the hub body (9) and, along the substantially radial extent, a leading edge region (14) and a trailing edge region (15) opposite the leading edge region (14), wherein the hub body (9) has a wall (17) in which depressions (19) are provided for receiving the blade feet (13), characterized in that on the outside of the wall (17), recesses (26) are provided which reach up to a part portion of the depressions (20), wherein, in the vicinity of the foot (13), each blade (7) has an extent which protrudes beyond the foot (13), is formed substantially by the leading edge region (14) and protrudes into the respective recess (26).

2. Stirrer arrangement (1) according to Claim 1, characterized in that the hub body (9) comprises a substantially cup-like base body (16).

3. Stirrer arrangement (1) according to one of Claims 1 or 2, characterized in that the hub body (9) is closed by a cover (22) at its free end.

4. Stirrer arrangement (1) according to any of Claims 1 to 3, characterized in that the hub body (9) comprises a bottom element (23) with a shaft receiver (24).

5. Stirrer arrangement (1) according to Claim 4, characterized in that the bottom element (23) is formed substantially conical, wherein the shaft receiver (24) has a substantially cylindrical form.

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