Eccentric screw pump

Abstract

Eccentric screw pump with a screw-shaped rotor and a stator made of an elastomer material in which the rotor rotates, forming several pump chambers, wherein the stator is vulcanized into a preferably metallic support tube, wherein the stator has at least one sensor which is inseparably connected to the stator - namely vulcanized into it.

Description

AREA OF INVENTION

[0001] The invention relates to an eccentric screw pump according to the preamble of claim 1 and to a method for manufacturing an eccentric screw pump according to the preamble of claim 12. TECHNICAL BACKGROUND

[0002] Currently, individual, high-priced industrial sensors, which are retrofitted to machines or systems, are mostly used for data recording on pumps and pumping systems during operation.

[0003] Particularly for the stators of progressive cavity pumps, no satisfactory application is known. Usually, only individual PT100 temperature sensors are retrofitted to the stator. These are used as dry-running protection. Where further operating data needs to be recorded, it is not uncommon to resort to installing expensive industrial sensors outside the rubber-elastic stator lining on the pump.

[0004] Insofar as individual sensors are already being installed in progressive cavity pumps and corresponding systems, their wiring is often problematic.

[0005] In the stators of progressive cavity pumps, an STP2 temperature sensor is usually retrofitted, which requires subsequent machining of the stator and usually also of the support tube holding the stator. This results in additional manufacturing effort.

[0006] Because these sensors are very expensive, as mentioned, many customers tend to order progressive cavity pumps without them. This means that potential faults or overloads of the pump are either not detected or are detected too late during operation. In practice, this often results in an unnecessarily shortened lifespan for the pump.

[0007] Another occasionally relevant aspect is that a design without sensors makes it easier for product pirates to offer copied stators.

[0008] Currently, any measuring technology used to equip a stator is attached after the stator has been manufactured. For this purpose, it is common practice to drill radially through the finished stator. This usually also involves drilling through the actual metal support tube that forms the housing for the stator. A metal sleeve with an external thread is then screwed into the stator, which in turn accommodates the respective sensor. This metal sleeve also serves to seal the stator. The sensor cables exit the metal sleeve on the side facing away from the rotor and are then pulled out through the metal support tube for the stator.

[0009] The metal sleeve is typically screwed into the stator in such a way that it is anchored only in the stator's elastomer material and not also in the metal support tube. This ensures that the metal sleeve does not impede the stator's radial expansion movements. However, as mentioned, this leads to a significantly increased manufacturing effort, which is unnecessarily costly. TASK OF INVENTION

[0010] Against this background, the object of the invention is to provide a means by which data from an eccentric screw pump can be easily and cost-effectively recorded during operation. INVENTIONAL SOLUTION

[0011] A solution to this problem is provided by the main claim.

[0012] According to the invention, an eccentric screw pump with a screw-shaped rotor and a stator made of an elastomer material is proposed, in which the rotor rotates, forming several pump chambers. The stator is vulcanized into a preferably metallic support tube. The eccentric screw pump is characterized in that the stator has at least one sensor that is inseparably connected to the stator—namely, that it is completely vulcanized into it or at least partially or over a single surface, namely at its edge or at the transition between the stator (i.e., the lining) and the support tube. In its broadest sense, "vulcanized in" here means being enclosed at its installation location by vulcanization.In this context, "inseparably connected" means that at least one sensor cannot be removed from the stator without causing damage to at least the elastomer material of the stator, even if such damage is repairable.

[0013] The vulcanization of the at least one sensor is preferably carried out simultaneously with the manufacturing of the stator itself. This generally significantly reduces manufacturing effort, as no additional manufacturing steps or subsequent machining of the stator are necessary.

[0014] By embedding the sensors in this way, it is also possible to use significantly less expensive sensors. Furthermore, the stator according to the invention can be identified more clearly as the original compared to copied stators. This is the case, at least, if the ID is encrypted and can be verified via certificates. PREFERRED FURTHER EDUCATION OPPORTUNITIES FOR INVENTION

[0015] A preferred design variant involves the at least one sensor being designed, mounted, and connected in such a way that it transmits meaningful data—in an evaluable form—during the vulcanization of the stator into its associated support tube. This allows for direct, live monitoring of the vulcanization process. Furthermore, it is possible—especially when a storage device is also vulcanized—to track the influence of specific process data from the vulcanization process on the progressive cavity pump throughout its entire service life. This allows for verification of the success of the critical manufacturing process of the vulcanization and provides insights into potential optimizations to the vulcanization process based on the performance of returned units.

[0016] Furthermore, the process data from manufacturing and the operating data of the stator can be used to better detect any potential dry running.

[0017] Furthermore, it is particularly preferred if the at least one sensor is fixed to the inner circumferential surface of the support tube. It can be fixed completely or substantially, or at least over more than just a small portion of its surface. This "fixing" is generally independent of the vulcanization process. It is preferably achieved by bonding the at least one sensor to the metal support tube, particularly preferably on the inner circumferential side facing the stator. On the one hand, this fixing ensures that the at least one sensor is securely connected to the support tube during the vulcanization process and is not unintentionally "washed away" during vulcanization. On the other hand, the metal support tube acts as a heat sink during vulcanization, thus reducing the thermal load on the sensor. At the very least, it shortens the time it takes for the support tube to heat up, as it also needs to do so.Ideally, an adhesive is used that improves heat transfer between the sensor and the support tube.

[0018] Furthermore, it is particularly preferred if the at least one sensor is covered by an additional plastic seal. This plastic seal is preferably applied only after the at least one sensor has been attached to the support tube. Before application, and preferably also after application, the plastic seal is in a geometrically undefined state and is therefore preferably applied like paint or sealant. This is preferably a liquid or paste-like plastic seal that hardens only after application. The plastic seal securely holds the at least one sensor in position. It also serves to shield it from direct contact with the liquid elastomer compound used for vulcanization.

[0019] Another preferred embodiment consists of a connecting cable of the at least one sensor being led out from the elastomer material of the stator to the accessible outer surface of the support tube; preferably via the end annular surface of the support tube, which ideally is provided with a local recess that forms a passage for the connecting cable, wherein the connecting cable is also partially vulcanized into the elastomer material of the stator. This facilitates further connection of the at least one sensor. The connecting cable preferably serves to transmit the signal to the outside and, optionally, to supply the sensor with energy. Furthermore, in such an arrangement, the portion of the connecting cable that transitions into the connector is very easily and effectively strain-relieved.

[0020] It is particularly preferred if the at least one sensor is arranged on a flexible printed circuit board, the side of which facing away from the stator is bonded to the inner circumferential surface of the support tube. The flexible circuit board thus forms a perfectly flat bonding surface, allowing for large-area bonding. This further contributes to the simplicity and cost savings of the entire system.

[0021] Furthermore, it is particularly advantageous if the flexible printed circuit board is coated with a pressure-sensitive adhesive (PSA) on its side facing away from the stator. This PSA is preferably self-adhesive without curing and is applied like a sticker. This allows for very simple and quick assembly without any curing time after installation.

[0022] It is also preferred that the connecting cable and / or the connecting cables to other sensors are also designed as flexible printed circuit boards with printed conductor tracks, wherein the flexible printed circuit board is preferably formed in one piece, either entirely or at least across several sensors. This further contributes to the simplicity and cost savings of the entire system. Due to its flat surface area, such a flexible conductor track can be bonded to the support tube more easily and securely.

[0023] Furthermore, it is particularly preferred that an eccentric screw pump be equipped with several sensors positioned at a more than negligible distance from one another. This more than negligible distance exists when a sensor is at least 10 mm, preferably at least 20 mm, but at most 200 mm away from its neighboring sensor. In such eccentric screw pumps, it is preferred that the sensors are covered with elastomer material of the stator to varying thicknesses compared to one another. This means that not only are several sensors provided, all of which are always mounted at essentially the same location within the respective pump chambers, but their positions within the respective pump chambers vary.This allows different pressures and / or temperatures to be recorded and compared in the different areas of the pump chambers, for example to determine which area is under the highest load.

[0024] Another preferred embodiment consists in the fact that, in addition to the at least one sensor, a data storage device is vulcanized into the system, on which data can be stored – preferably encrypted or password-protected. The system is preferably designed so that such data can actually be stored and saved, such as an electronic nameplate and / or an operating log.

[0025] Furthermore, it is particularly preferred to use several different sensors, preferably at least two from the groups of pressure sensors, strain sensors, and inductive sensors. This allows the progressive cavity pump to be monitored in many different areas, enabling the rapid detection of faults and / or potential improvements.

[0026] Further possible configurations, functions and advantages will result from the dependent claims and / or the following description of the exemplary embodiment and / or with reference to the figures. LIST OF FIGURES

[0027] Figure 1 shows a cross-section of the stator 1 with the exemplary position of the individual sensors 3 on a flexible printed circuit board. Figure 2 shows the support tube without stator with fixed circuit board and outgoing connecting cable and connector in a three-dimensional view. Figure 3The support tube without stator, with fixed circuit board and external connecting cable and connector, is shown analogously to Fig. 2 in a modified three-dimensional view. Figure 4 shows a support tube with four flexible circuit boards arranged around the circumference of the stator in a three-dimensional view. Figure 5 shows a support tube with four flexible circuit boards arranged around the circumference of the stator, each with a plastic seal, in a three-dimensional view. Figure 6 shows a support tube with recesses on the end ring surface in a three-dimensional view. Figure 7 shows analogous to Fig. 5 A support tube with four flexible circuit boards arranged around the circumference of the stator, from another three-dimensional view. Figure 8 shows the stator in its vulcanized state in a three-dimensional view. PREFERRED FORM OF EXECUTION

[0028] In general, inexpensive sensors 3 (including evaluation unit and gateway) according to the invention are preferably used.

[0029] The sensors 3 are preferably NTC sensors for measuring temperature. Due to a temperature of 150°C in the vulcanization bath during the vulcanization of the stator 1, such sensors 3 must be selected with appropriate temperature resistance. Several of these sensors 3 are preferably positioned in series on a flexible plastic strip, on which the conductive traces are also located. This creates the aforementioned flexible printed circuit board 7. The flexible printed circuit board 7 also preferably has at least one connecting cable 5 and a connector, preferably in the form of a plug connector 11, to establish the connection to the evaluation unit. The sensors 3 are preferably coated with a plastic seal 4 made of epoxy resin to protect them from the liquid in the vulcanization bath. The printed circuits are preferably manufactured very cost-effectively using a rotary printing process.

[0030] These flexible printed circuit boards 7 can also be equipped with other sensors 3 such as magnetometers (e.g., for use in the stator to measure rotor rotations), accelerometers (e.g., for use in the stator to analyze vibrations), pressure sensors, or ID chips. The length, number, and type of sensors are freely configurable depending on the application.

[0031] These flexible printed circuit boards 7 with sensors 3 attached to them, connecting cables 5 and connecting connectors 11 are integrated into the stator 1 according to the invention, preferably vulcanized in. The stator 1 is mounted in a preferably metallic support tube 2, preferably vulcanized into this support tube 2.

[0032] Fig. 1Figure 1 shows a cross-section of the stator 1 with an exemplary position or arrangement of the individual sensors 3 on a flexible printed circuit board 7, preferably temperature sensors, as well as the respective thicknesses of the elastomer layer covering the sensors at their respective sensor locations. As mentioned, it is preferred that the sensors 3 are covered with elastomer material of the stator 1 of varying thicknesses compared to each other. This means that not only are several sensors 3 provided, always mounted at essentially the same location in the respective pump chambers, but their position within each pump chamber varies. This allows for the measurement and comparison of different pressures and / or temperatures in different areas of the pump chambers, for example, to determine which area is subjected to the highest load.

[0033] In Fig. 1An example of an STP2 sensor 9 is also shown, which, according to the prior art before this invention, was provided in the stator 1.

[0034] According to the invention, the flexible circuit board 7 is at least partially vulcanized into the stator 1. Preferably, the connecting cable 5 is only partially vulcanized, and the connector 11 is not vulcanized at all. The connecting cable 5 is led out of the stator 1 at one end of the support tube 2, where the connector 11 is located. The position of the connector 11 and the fixed circuit board 7 is defined in the Fig. 2 and Fig. 3 schematically represented.

[0035] Not only can any number of sensors 3 be arranged axially (along the length) on the flexible circuit board 7, but multiple flexible circuit boards 7 can also be integrated radially into the stator 1. For example, a manufacturing trial was also carried out with four flexible circuit boards 7 with sensors 3 arranged around the circumference of the stator 1. This schematic setup is shown. Fig. 4 In Fig. 4 As an example, one of the flexible circuit boards 7 was provided with a plastic seal 4.

[0036] The flexible circuit board 7 is inserted internally between the support tube 2 of the stator 1 and the elastomer material that forms the stator 1. For this purpose, the circuit board 7 must be fixed to the inner circumferential surface of the support tube 2, preferably by bonding. Due to the further connection using the connector 11, the connecting cable 5 must also be routed to the outside to ensure the connection to the evaluation unit.

[0037] The final fixing of the flexible printed circuit board 7 in the support tube 2 is preferably achieved using epoxy resin as a plastic seal 4 to protect the NTC sensors. However, it is also possible to use only a single-sided adhesive tape for fixing and to completely omit the plastic seal 4. This depends on the properties of the flexible printed circuit board 7.

[0038] Fig. 5 and Fig. 7 The figures show, by way of example, how four flexible circuit boards 7 arranged around the circumference of the stator 1 were provided with a plastic seal 4 and how the connecting cables 5 were routed out of the support tube.

[0039] The connecting cables 5 of the printed circuit board 7 are preferably guided outwards at both ends via end-face recesses 6 in the end-face annular surface 8 of the support tube 2 and preferably secured with pipe clamps 10. These pipe clamps 10 help to reduce wear on the connecting cable. It is important to make the bend radii sufficiently large, as otherwise the connecting cable 5 may tear at the bend points. Fig. 6 shows in detail the aforementioned recesses 6 on the end ring surface 8 of a support tube 2.

[0040] Once the plastic sealant 4 has dried, it may be necessary to provide all connecting cables 5 and connectors 11 outside the support tube 2 with a protective sheath, such as by wrapping them with insulating tape. The tape serves to seal against the oil mixture in the vulcanization bath or generally as protection against mechanical, thermal, and / or chemical damage. However, it is also possible to use waterproof and oil-resistant cables and connectors, thus eliminating this manufacturing step.

[0041] Due to the recesses 6 through which the connecting cable 5 is routed, a gap is created through which the elastomer can ooze out during the extrusion process. This protruding elastomer must then be cut off before immersion in the vulcanization bath.

[0042] Generally, during vulcanization, the support tube 2 in the vulcanization mold is immersed in the vulcanization basin. Fig. 8shows the stator 1 according to the invention in its vulcanized form.

[0043] It is essential to ensure that connector 11 is submerged to prevent oil from contaminating the contacts. However, waterproof and oil-resistant connectors can be used, eliminating this step. Furthermore, connector 11 should have a high temperature resistance of up to approximately 150°C.

[0044] After the vulcanization bath is complete, stator 1 is immersed in a water bath in the vulcanization mold to cool. During this entire manufacturing process, various data, especially temperature data, can be recorded by the sensors to allow for conclusions to be drawn about the manufacturing process.

[0045] During operation of the progressive cavity pump, the temperatures are recorded using the manufactured stator 1 with integrated temperature sensors 3, while following a pump characteristic curve with different speeds, preferably between 150 rpm and 600 rpm, and pressures, preferably between 0 bar and 12 bar. The pressure fluctuations are thus reflected in the temperatures. In this way, essential data from the progressive cavity pump can be collected even during operation.

[0046] In general, the flexible circuit board 7 mentioned above ultimately serves as a replacement for a multi-core cable. Because it is flat and offers a relatively large adhesive surface, the flexible circuit board 7 can be very effectively bonded to the inner surface of the support tube 2, currently, in the experimental stage, using epoxy resin. Later, the plan is to coat the side of the flexible conductor facing the support tube with a pressure-sensitive adhesive (PSA), making it self-adhesive after removing the protective film. It may still be necessary to apply some protective epoxy resin locally in the area of ​​the sensors 3. However, this is not required along the entire length of the flexible circuit board 7. Ideally, the epoxy resin can be omitted entirely if the respective sensor 3 is completely encapsulated, so that the liquid elastomer cannot damage it.

[0047] Preferred sensors include pressure sensors, temperature sensors, inductive sensors, or similar devices, for example, to measure the rotor's rotation, and / or sensors whose resistance changes under deformation. In many cases, it is also advantageous to vulcanize in a memory module, which then serves as a virtually tamper-proof electronic nameplate. This module can store various pieces of information specific to the eccentric screw pump, ensuring that this information remains with the pump throughout its service life.

[0048] It is particularly attractive to design the sensors in such a way that they can already be operational in the next step, namely when stator 1 is vulcanized in place, and record data from this production process, for example, data that can be used to prove that this production process as a whole has proceeded correctly. Furthermore, operating hour data and similar information can also be stored here.

[0049] One could, of course, also route the connector 11 through a radial bore in the area of ​​the support tube end. However, this would mean that the wide flat connector could not be pre-mounted and would have to be installed afterward, or that a relatively large window would have to be made in the support tube 2 for the stator 1 in order to insert the flat connector. Both of these problems can be avoided if the flat connector is pulled outward over the end face of the support tube 2 and over the aforementioned recess 6. MISCELLANEOUS

[0050] Protection will also be claimed in due course for the use of one or more sensors, which for this purpose are mounted on the support tube of an eccentric screw pump and preferably on its inner surface, for measuring data during the vulcanization of the elastomeric stator by immersion.

[0051] This can be further refined by completely immersing one or more sensors, along with the support tube, in the vulcanization bath.

[0052] This can be further elaborated upon by additional features from the description, the figures and / or the claims. REFERENCE LIST

[0053] 1 Stator 2 Support tube 3 Sensor 4 Plastic seal 5 Connection cable 6 Return 7 Circuit board 8 Face ring surface 9 STP2 sensor 10 Pipe clamp 11 Connector

Claims

1. Eccentric screw pump with a screw-shaped rotor and a stator (1) made of an elastomer material in which the rotor rotates, forming several pump chambers, wherein the stator (1) is vulcanized into a preferably metallic support tube (2), characterized by the fact that the stator (1) has at least one sensor (3) which is inseparably connected to the stator (1) - namely vulcanized into it.

2. Eccentric screw pump according to claim 1, characterized by the fact that the at least one sensor (3) is designed, attached and connected in such a way that it already provides data during the vulcanization of the stator (1) into the support tube (2) assigned to it.

3. Eccentric screw pump according to one of the preceding claims, characterized by the fact that where at least one sensor (3) is fixed to the inner circumferential surface of the support tube (2).

4. Eccentric screw pump according to one of the preceding claims, characterized by the fact thatwhere at least one sensor (3) is covered by an additional plastic seal (4) which is in a geometrically undefined state, i.e., applied like paint or sealant.

5. Eccentric screw pump according to one of the preceding claims, characterized by the fact that A connecting cable (5) of the at least one sensor (3) is led out of the elastomer material of the stator (1) to the accessible outside of the support tube (2); preferably via the end ring surface (8) of the support tube (2), which ideally is provided with a recess (6) for this purpose, forming a passage for the connecting cable (5), wherein the connecting cable (5) is also vulcanized in the elastomer material of the stator (1) in certain areas.

6. Eccentric screw pump according to one of the preceding claims, characterized by the fact thatthe at least one sensor (3) is arranged on a flexible circuit board (7) which is bonded to the inner circumferential surface of the support tube (2) with its side facing away from the stator (1).

7. Eccentric screw pump according to one of the preceding claims, characterized by the fact that the flexible printed circuit board (7) is coated with a PSA on its side facing away from the stator (1).

8. Eccentric screw pump according to one of the preceding claims, characterized by the fact that The connecting cable (5) and / or the connecting cables to further sensors are also designed as a flexible printed circuit board (7) with printed conductor tracks, wherein the flexible printed circuit board (7) is preferably formed in one piece overall or at least over several sensors (3).

9. Eccentric screw pump, preferably according to one of the preceding claims, with several sensors (3) positioned apart from one another, characterized by the fact thatThe sensors (3) are covered with elastomer material of the stator (1) of different thicknesses compared to each other.

10. Eccentric screw pump according to one of the preceding claims, characterized by the fact that In addition to at least one sensor (3), a data storage device is vulcanized in, on which data can be stored.

11. Eccentric screw pump according to one of the preceding claims, characterized by the fact that several different sensors (3) are provided, preferably at least two from the group of pressure sensors, strain sensors and inductive sensors.

12. Method for manufacturing an eccentric screw pump, characterized by the fact thatat least one sensor (3) is attached to a support tube (2) which is not yet equipped with a stator (1) and made ready for operation, and then the support tube (2) is flooded with elastomer mass to be vulcanized, at least in the areas where the stator (1) is to be pre-formed, and then vulcanized by applying heat, and at least one data value of the at least one sensor (3) is used, preferably in order to trigger an activity if required that changes at least one parameter of the vulcanization process.

13. Method according to claim 12, characterized by the fact that the recess (6) in the end ring surface (8), through which the connecting cable (5) is led to the outside, is closed by vulcanizing the stator (1).

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