Eccentric screw pump

Abstract

The invention relates to an eccentric screw pump, comprising a rotor consisting of a drive shaft, which rotates substantially about a fixed axis relative to a stator in a bearing block, a drive train, and a screw conveyor, which rotates in a rotationally oscillating manner in the screw lead of the stator, the drive train provides its drive torque to the auger and balances differences during movement of the auger and the drive shaft, where the drive train consists essentially of a one-piece rotating body having a plurality of weakening grooves, which are arranged in the direction of the rotation of the auger and the drive shaft. The weakened grooves not only slightly interrupt its peripheral sheath surface and provide them with a reversible elasticity required for rotation about an axis of rotation that is at least partially curved in a periodically repeating manner.

Description

Technical Field

[0001] The invention relates to an eccentric screw pump according to the preamble of claim 1 , having a rotor with a drive shaft, a drive train and a conveyor screw, and a corresponding drive train according to the preamble of claim 8 . Background Art

[0002] Eccentric screw pumps belong to the rotary positive displacement pump group and are mainly used to transport a variety of media, especially viscous, highly viscous and abrasive media. The main components of an eccentric screw pump are a rotating rotor and a fixed stator.

[0003] The rotor of the eccentric screw pump is preferably formed by the drive shaft of the drive motor, the transmission and the screw conveyor. The screw conveyor is preferably spirally wound and moves in a fixed stator in a rotating oscillating manner. At present, the screw conveyor is mostly hinged on one side or attached in an elastic manner.

[0004] The drive train provides the screw conveyor with its drive torque, which compensates for the differences in the motion of the screw conveyor and the drive shaft. During the rotational motion, the eccentricity between the drive shaft and the screw conveyor particularly needs to be balanced.

[0005] According to the prior art, this is currently achieved mainly by means of a long connecting rod, which has a joint at each end, similar to the case of a cardan shaft.

[0006] This results in a high number of components and long installation lengths (especially the necessary length of the connecting rods). There is a risk of wear at the joints. In addition, lubrication of the joints is usually required, which on the one hand means additional costs and on the other hand leads to the risk of lubricant entering the medium to be conveyed.

[0007] According to the prior art, connecting rods manufactured by means of known production methods have a high wear rate to a certain extent and require cost-intensive maintenance. In addition, the production of its products by means of current production methods is mostly cost-intensive. Summary of the invention

[0008] Purpose of the invention

[0009] The object of the present invention is therefore to specify a method by means of which a high-capacity and cost-effective connection between a drive shaft and a screw conveyor can be achieved.

[0010] Solution of the present invention

[0011] The solution to this object is provided by the first independent claim.

[0012] For this purpose, an eccentric screw pump is proposed, which comprises a rotor with a drive shaft rotating substantially about a fixed axis relative to a stator in a bearing seat, a drive train and a screw conveyor, wherein the screw conveyor rotates in a rotationally oscillating manner in the screw lead of the stator.

[0013] The drive train provides the screw conveyor with its drive torque, and the drive train balances the differences in motion between the screw conveyor and the drive shaft, as described above.

[0014] The eccentric screw pump according to the invention is characterized in that the drive train consists essentially of a one-piece rotating body having a plurality of weakening grooves which interrupt its peripheral jacket surface more than slightly, wherein the weakening grooves preferably extend mainly in the radial direction or extend essentially in the radial direction. In any case, the weakening groove extends essentially in the radial direction when its height is greater than its width, wherein the height is defined by its maximum expansion in the radial direction and the width is defined by its maximum expansion in the axial direction.

[0015] The weakening groove is designed in such a way that it provides the drive train with reversible elasticity, which is required for the drive train to rotate about an axis of rotation which is at least partially curved in a periodically repeating manner. During operation of the eccentric screw pump, due to the difference in the motion sequence between the screw conveyor and the drive shaft, an axis of rotation which is at least partially curved in a periodically repeating manner is formed, as described above.

[0016] In general, the drive train according to the invention is preferably connected directly or indirectly on one side to the drive shaft and directly or indirectly on the other side to the screw conveyor. Due to the weakening groove and the elasticity of the drive train associated therewith, the drive train can compensate for the above-mentioned eccentricity, wherein even in the case of a changed joint spacing, in particular a shortened joint spacing compared to the prior art, the drive train still provides the necessary rigidity for a safe transmission of torque.

[0017] Since the drive train consists essentially of a one-piece rotating body, the number of components and the production costs are significantly reduced compared to the prior art. The installation length can also be shortened compared to the prior art. Since preferably no external joints are used for the connection, the maintenance effort and the tendency to wear can also be reduced here.

[0018] The “weakened grooves” of the rotating body are preferably notches and / or depressions which extend substantially radially from its peripheral jacket surface in the direction of its axis of rotation, thereby interrupting its peripheral jacket surface.

[0019] Therefore, this interruption of the peripheral sheath surface is "more than negligible", and (not only that, but) this interruption is achieved at least when the maximum width of the weakening groove is at least 3mm, preferably at least 5mm and the maximum height is at least 10mm, preferably at least 15mm.

[0020] Regardless, a "one-piece" component in the context of the present invention refers to a coherent component, at least 95% of which is composed of a homogeneous material, and is preferably a component that is molded as a one-piece component.

[0021] The preferred design of the present invention

[0022] A preferred embodiment of the eccentric screw pump according to the invention is that the rotating body forming the drive train consists essentially of a polymer material (preferably formed in one piece) and, ideally, of a polyamide, or of a metal material (preferably formed in one piece). As a result, the production costs of the drive train can be kept low, but the required elasticity and stiffness properties can still be obtained, and in most cases it can also be arranged in a very sensitive construction mode. 3D printing of plastics and / or metals (especially out of the powdered original shape) has proven to be a particularly effective and therefore preferred solution to the problems to be solved here, although the production process is mandatory and is still very time-consuming in the case of such large components. This 3D printing leaves a special inter-grain structure (Interkorn-Struktur), in which a certain, at least roughly controllable degree of weakening is inherent in the interconnected grain boundary region. This results in a unique (different from other molding methods of these materials) flexibility and / or damping properties, which can be used for the purposes of the present invention and lead to surprisingly significant improvements in the results.

[0023] It is therefore easy to understand that, in a first approximation, it is particularly preferred if the drive train has a grain structure that does not completely merge seamlessly into one another in a cross-section - preferably when viewed at a magnification of up to 10 times. The resulting "built-in" porosity or microstructure weakened by microcavities has a positive effect on the elasticity of the drive train.

[0024] Another preferred embodiment of the eccentric screw pump according to the invention is that the rotating body forming the drive train consists of a plurality of discs, wherein directly adjacent discs are connected to each other via single or multiple partial strips, which are elastic so that, at each rotation, the adjacent discs can perform a swinging movement relative to each other around the strip, which swinging movement is generally reversibly elastic (preferably ≥ 0.75 mm in the direction of the axis of rotation or its local tangent is also not negligible), wherein directly adjacent strips are arranged in a position rotated relative to each other. In addition, adjacent or directly adjacent strips are respectively ideally arranged to rotate relative to each other so that the longitudinal axes of the strips extend at right angles to each other.

[0025] Thus, on the one hand the desired elasticity is achieved and on the other hand the rigidity required for transmitting torque is ensured.

[0026] In addition, it is particularly preferred that the rotating body forming the drive train has a connecting member on its side facing away from the screw conveyor, which can be connected to the form-fitting member (Formschlussorgan) of the drive shaft in a rotationally fixed manner. Therefore, the connection for torque transmission between the drive shaft and the drive train can be realized in a simple manner.

[0027] Furthermore, it is particularly preferred that the rotating body forming the drive train has an opening or a tubular appendage on its side facing the screw conveyor, which opening or tubular appendage has such a property that, due to its spiral shape, the end of the screw conveyor can be firmly held therein in a form-fitting, non-rotatable manner. The opening or the tubular appendage also preferably has a spiral shape at least in part. Thus, a torque-transmitting connection between the screw conveyor and the drive train can be realized in a simple manner.

[0028] Furthermore, it is particularly preferred that the opening or the tubular attachment has at least one threaded hole on the side facing the screw conveyor. The threaded hole is preferably used to introduce a screw or a threaded pin, particularly preferably a grub screw, for additionally fixing the screw conveyor in the opening or the tubular attachment.

[0029] Further configuration options, modes of operation and advantages can be derived from the description of the exemplary embodiments and / or based on the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The eccentric screw pump according to the invention is shown in a three-dimensional view.

[0031] Figure 2 The drive train according to the invention is shown in a three-dimensional view.

[0032] Figure 3 Shown in top view Figure 2 A transmission system according to the present invention.

[0033] Figure 4 Shows Figure 2 A drive train according to the invention with a connected screw conveyor and an alternative connecting member.

[0034] Figure 5 A further exemplary embodiment of a drive train according to the invention is shown with a printed auger.

[0035] Figure 6 A further embodiment of a drive train according to the invention is shown with additional ribs.

[0036] Preferred exemplary embodiments

[0037] Figure 1 First, an eccentric screw pump 1 according to the invention is shown. The eccentric screw pump 1 comprises a rotor, which in turn comprises a drive shaft 2, a transmission system 3 and a screw conveyor 4. The screw conveyor 4 rotates in a stator 5 in a rotationally oscillating manner. Figure 1 As shown, the drive shaft 2 rotates in a bearing support 6. The bearing support 6 preferably has an integrated rolling bearing. The drive train 3 preferably represents a direct connection between the drive shaft 2 and the screw conveyor 4.

[0038] Figure 2 and Figure 3 A first exemplary embodiment of the drive train 3 is shown in more detail. The drive train 3 consists essentially of a one-piece rotating body having a plurality of weakening grooves 7. The weakening grooves 7 are preferably embodied and arranged in such a way that the rotating body consists of a plurality of disks 8, wherein directly adjacent disks 8 are connected to one another via strips 9. The strips 9 are preferably arranged such that directly adjacent strips 9 are rotated relative to one another so that the strip longitudinal axes extend completely or at least essentially at right angles to one another.

[0039] Preferably, the outermost discs, i.e. one of the discs 8 closest to the drive shaft 2 and / or one of the discs 8 closest to the screw conveyor 4, may in each case have a different shape than the other discs 8. These outermost discs 8 are preferably thicker than the other discs 8.

[0040] The connecting member 10 can be connected to a form-fitting member of the drive shaft 2 in a rotationally fixed manner, the connecting member 10 being preferably located in the direct vicinity of the outermost disk 8 closest to the drive shaft 2 .

[0041] An opening or (as in the exemplary embodiment shown) a tubular attachment 11, such as Figure 2 and Figure 3, preferably located directly adjacent to the outermost disk 8 closest to the screw conveyor 4. This tubular attachment 11 has the property that, due to its spiral shape, the end of the screw conveyor 4 can be fixed therein in a form-fitting, non-rotatable manner. The fixing position of the inserted screw conveyor 4 can be Figure 4 Furthermore, the threaded hole is also preferably attached (usually a metal threaded bushing is "transferred" on its circumferential sheath) to the tubular attachment 11, particularly preferably even directly adjacent to the outermost disk 8. With the aid of this threaded hole, an additional fixing element, preferably a screw or a threaded pin, particularly preferably a grub screw 12, can be screwed in. In most cases, this provides a pull-out protection against longitudinal pull-out or unwanted unscrewing in reverse operation and / or an overall fixing of the connection, respectively.

[0042] also, Figure 3 Also shown are some measurements with the help of which the preferred dimensions of the drive train 3 according to the invention can be specified. Thus, the angle a between two adjacent discs 8 is preferably in the range of 0° to 30°. This contributes to achieving the required flexibility of the drive train 3. The diameter d of the discs 8 is preferably substantially the same for all discs 8 of the drive train. The length l preferably represents the maximum dimension in the axial direction from the outermost disc 8 closest to the screw conveyor 4 to the outermost disc 8 closest to the drive shaft 2. The ratio k of the diameter d to the length l is preferably between 0.3 and 1. Thus, the axial expansion of the drive train 3 is preferably greater than the radial expansion, which contributes to achieving the required flexibility. The eccentricity e is preferably the distance (or position difference) between the axis of the connecting member 10 and the axis of the vertical end of the tubular attachment 11, which axis points in the direction away from the screw conveyor 4. The ratio of the eccentricity e to the ratio k is preferably in the range of 1 to 4. In addition, in Figure 3 A repeating portion or repeat n can be seen in . Therefore, the ratio of n to the ratio k is preferably in the range of 5 to 50.

[0043] Figure 4 Shows Figure 2 and Figure 3 3, wherein an alternative connecting member 10 is shown, which is preferably printed on the outermost disc 8 closest to the drive shaft 2. Although Figure 2 and Figure 3 The connecting member 10 shown in FIG. 1 is preferably received by the drive shaft 2 in a form-fitting, rotationally fixed manner, while Figure 4 The connecting component 10 shown in FIG. 2 then receives the drive shaft 2 in a form-fitting, rotationally fixed manner.

[0044] Figure 5Another embodiment of the drive train 3 is shown, in which the outermost disc 8 closest to the screw conveyor 4 is directly connected to the screw conveyor 4, and the outermost disc 8 is preferably printed on the screw conveyor 4. The drive train 3 and in particular its discs 8 are thus designed to be essentially flat. In contrast, the discs 8 of the first embodiment are curved and / or implemented with variable thickness. Both embodiments of the discs 8 are feasible.

[0045] Figure 6 A further embodiment of a drive train according to the invention is shown, which has additional ribs 13. These ribs 13 take over the conveying function and cause the product to be pushed forward in the direction of the conveyor screw 3.

[0046] Reference numerals list

[0047] 1 Eccentric screw pump

[0048] 2 Drive shaft

[0049] 3 Drivetrain

[0050] 4 Screw conveyor

[0051] 5. Stator

[0052] 6 Bearing seat

[0053] 7 Weakening groove

[0054] 8 disc

[0055] 9 strips

[0056] 10 Connecting components

[0057] 11 Tubular accessories

[0058] 12 Flat head screw

[0059] 13 Rib

[0060] a angle

[0061] d diameter

[0062] e Eccentricity

[0063] Length

[0064] Repeat

Claims

1. An eccentric screw pump (1) having a rotor, the rotor consisting of a drive shaft (2), a transmission (3) and a screw conveyor (4), the drive shaft rotating substantially about a fixed axis relative to a stator (5) in a bearing seat (6), the screw conveyor (4) rotating in a rotationally oscillating manner in the screw lead of the stator (5), wherein: The transmission system (3) provides the screw conveyor (4) with its driving torque, and the transmission system (3) compensates for the differences in the movement processes of the screw conveyor (4) and the drive shaft (2), and is characterized in that the transmission system (3) is basically composed of a one-piece rotating body, which has a plurality of weakening grooves (7), which not only slightly interrupt the outer peripheral jacket surface of the transmission system (3) and provide the transmission system (3) with reversible elasticity, which is required for rotation around an axis of rotation, and the axis of rotation is at least partially bent in a periodically repeated manner.

2. The eccentric screw pump (1) according to claim 1, characterized in that: The rotating body forming the drive train (3) consists essentially of a polymer material, preferably is formed in one piece from a polymer material, and ideally consists of polyamide, or consists of a metal material, preferably is formed in one piece from a metal material.

3. The eccentric screw pump (1) according to claim 1, characterized in that: The transmission system (3) has a granular structure in cross section that is not completely seamlessly fused with each other.

4. An eccentric screw pump (1) according to any one of the preceding claims, characterized in that The rotating body forming the transmission system (3) is composed of a plurality of disks (8), wherein directly adjacent disks (8) among the plurality of disks (8) are connected to each other via strips (9), and the strips (9) are elastic so that at each rotation, the adjacent disks (8) can perform a swinging movement relative to each other around the strips (9), wherein the directly adjacent strips (9) are arranged in a position rotated relative to each other.

5. An eccentric screw pump (1) according to any one of the preceding claims, characterized in that The rotating body forming the drive train (3) has a connecting element (10) on its side facing away from the screw conveyor (4), which can be connected to a positive-fitting element of the drive shaft (2) in a rotationally fixed manner.

6. An eccentric screw pump (1) according to any one of the preceding claims, characterized in that The rotating body forming the drive train (3) has an opening or a tubular appendage (11) on its side facing the screw conveyor (4), which is of such a nature that, due to the spiral shape of the screw conveyor (4), the end of the screw conveyor (4) can be firmly held therein in a form-fitting, non-rotatable manner.

7. The eccentric screw pump (1) according to claim 6, characterized in that: On the side facing the screw conveyor (4), the opening or the tubular appendage (11) has at least one threaded hole, preferably for receiving a grub screw (12).

8. A transmission system (3) of an eccentric screw pump (1), characterized in that: The transmission system (3) is essentially composed of a one-piece rotating body, which has a plurality of weakening grooves (7), which not only slightly interrupt the outer peripheral jacket surface of the transmission system (3) and provide the transmission system (3) with reversible elasticity, which is required for rotation around an axis of rotation, and the axis of rotation is at least partially bent in a periodically repeated manner.

9. The transmission system (3) according to claim 8, characterized in that The drive train (3) has the features of one or more of claims 2 to 7 for the drive train (3).

10. Use of a plastic or metal material, preferably molded from a powder phase, by 3D printing as a drive train (3) for the torque-transmitting connection of two components which perform rotational movements about different axes.

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