Eccentric screw pump with magnetic coupler

Abstract

The invention relates to an eccentric screw pump having a rotor consisting of a pump drive shaft which rotates substantially about a stationary axis relative to a stator in a bearing block and which is rotationally driven by a motor drive shaft of a motor, a drive train and a screw conveyor, the screw conveyor rotates in a rotationally oscillating manner in the screw lead of the stator, where the drive train provides its drive torque to the screw conveyor, and the drive train balances the differences in the motion process of the screw conveyor and the pump drive shaft. Therefore, there is an air gap between the motor drive shaft and the pump drive shaft, the motor drive shaft supporting the motor-side coupling half and the pump drive shaft supporting the pump-side coupling half, the motor-side coupling half and the pump-side coupling half being connected to one another in a torque-transmitting manner by means of a magnetic force through the air gap, the air gap being penetrated by a seal, the seal sealingly separates the motor region from the remainder of the eccentric screw pump.

Description

Technical Field

[0001] The invention relates to an eccentric screw pump, the rotor of which is a pump drive shaft, which rotates substantially about a fixed axis relative to a stator in a bearing seat. The pump drive shaft is driven in rotation by a motor drive shaft of a motor. The eccentric screw pump has a drive train and a screw conveyor, which rotates in a screw pitch of the stator in a rotary oscillating manner. The drive train thus provides the screw conveyor with its drive torque and compensates for differences in the motion sequences of the screw conveyor and the pump drive shaft. Background Art

[0002] Eccentric screw pumps are known in the prior art.

[0003] EP 2944819B1 relates to an eccentric screw pump, comprising: a rotor extending from a drive end to a free end along a longitudinal axis of the rotor; a stator housing having an inner space extending from a stator inlet to a stator outlet along the longitudinal axis and formed to receive the rotor; a drive motor having a drive shaft coupled to the rotor to transmit torque; a first universal joint inserted in the torque transmission between the drive shaft and the rotor; and a stator output flange arranged downstream of the rotor in the flow direction.

[0004] The motor-side end of the eccentric screw pump is sealed by means of a sliding ring seal in the same manner as is customary for eccentric screw pumps.

[0005] A disadvantage of such seals is that critical substances, in particular irritating or toxic substances, cannot be pumped or can be pumped only to a limited extent. This is because, even in normal operation, such mechanical seals always have a certain amount of leakage, and at least a small leakage flow of the fluid to be sealed enters the sealing gap, in most cases acts as a lubricant there, then evaporates and leaves the sealing gap in a gaseous state, thus making the seal appear to be impeccable. Summary of the invention

[0006] Basic Purpose

[0007] The object of the present invention is to provide an eccentric screw pump which can also pump critical fluids, in particular toxic, irritating or environmentally harmful fluids, without fear of contamination or emissions.

[0008] Solution of the present invention

[0009] The above basic problem is solved by means of an eccentric screw pump with a rotor consisting of a pump drive shaft that rotates essentially about a fixed axis relative to a stator in a bearing housing. The pump drive shaft is driven in rotation by a motor drive shaft of a motor. The pump drive shaft is connected via a drive train to a screw conveyor, which rotates in a rotationally oscillating manner in the screw lead of the stator. The drive train thus provides the screw conveyor with its drive torque. At the same time, the drive train compensates for differences in the motion processes of the screw conveyor and the pump drive shaft.

[0010] According to the invention, the eccentric screw pump is characterized in that an air gap exists between the motor drive shaft and the pump drive shaft, and the motor drive shaft supports the motor-side half coupling, the pump drive shaft supports the pump-side half coupling, the motor-side half coupling and the pump-side half coupling are connected to each other in a torque-transmitting manner by means of magnetic forces across the air gap. The air gap is penetrated by a seal, which seals the motor region from the rest of the eccentric screw pump in a sealed manner.

[0011] The motor drive shaft (ie the motor shaft for driving the eccentric screw pump) and the pump drive shaft are not physically directly connected to each other.

[0012] The gap between the motor-side coupling half and the pump-side coupling half, called the air gap, can be filled with air or another medium, such as the fluid to be pumped. The medium should therefore not contain any ferromagnetic material or substantially no ferromagnetic material, which would prevent the transmission of magnetic forces through the air gap. The air gap must be large enough so that even under the influence of vibrations or shocks, the two coupling halves of the magnetic coupling do not actually come into contact with the seal penetrating the air gap. Harmful friction forces and mechanical wear are thereby prevented.

[0013] The air gap is penetrated by a seal, for example in the form of a cylindrical air separation can, in order to seal the motor region from the rest of the eccentric screw pump so that the pumped fluid cannot enter the motor region.

[0014] Therefore, the seal should not contain any ferromagnetic material or should contain substantially no ferromagnetic material that would hinder the transmission of magnetic forces across the air gap and the seal.

[0015] A further advantage of the eccentric screw pump embodied according to the invention is that, even under the influence of abrasive media, the seal of the eccentric screw pump facing the motor shaft is substantially wear-free, which avoids or extends maintenance intervals and is beneficial to the service life.

[0016] The seal can advantageously be embodied as a preferably cylindrical air separation can, the open side of which rests on the bearing support and forms a cavity which projects beyond the bearing support and receives the pump-side coupling half.

[0017] The cylindrical air gap tank has a cavity which receives the pump-side half coupling, so that the air separation tank can be arranged in a space-saving manner and the structure according to the invention can be provided on an existing bearing seat without requiring extensive structural changes to the bearing seat. Thus, a conventional eccentric screw pump can be equipped with the structure according to the invention in a simple manner.

[0018] The motor-side and pump-side coupling halves are advantageously designed and magnetically mounted such that they rotate synchronously with one another (in undisturbed nominal operation of the eccentric screw pump), preferably without any slip.

[0019] If slippage occurs, the strong magnets of the two coupling halves of the magnetic coupling will generate high eddy currents, which will quickly thermally destroy the magnetic coupling.

[0020] The eccentric screw pump can advantageously be equipped with a thermal sensor or, less preferably, with another slip detector which triggers an alarm and / or initiates slip-terminating measures as soon as slip occurs between the coupling halves.

[0021] This ensures that the eccentric screw pump will not be damaged in the event of an overload or even in the event of an accidental seizure of the eccentric screw due to slip-related overheating in the area of ​​the coupling halves.

[0022] The pump-side coupling half can advantageously be cooled by means of the fluid pumped by the eccentric screw pump, ie ideally by means of direct contact.

[0023] The pump drive shaft can advantageously, preferably on its front end region facing away from the screw conveyor, carry pump means, more preferably a pump wheel, ideally a centrifugal pump wheel, which drives the fluid through the air gap.

[0024] Thus, by means of the pump device (for example a centrifugal pump wheel), a flow is generated at least partially at the pump drive shaft through the air gap, which flow can be used for cooling or flushing purposes.

[0025] The flow through the air gap can be driven or generated in a supporting manner by the pump device or can be driven or generated substantially exclusively by means of the pump device, respectively.

[0026] The pump drive shaft can advantageously be supported on rolling bearings and / or sliding bearings, preferably in a bearing seat.

[0027] Rolling bearings have the advantage that they can flow more easily in the transverse direction, so that the fluid can more easily reach the pump-side coupling half to be cooled or can drain away therefrom.

[0028] The rolling bearings can be implemented as ceramic bearings, which results in a longer service life and reduced maintenance compared to metal bearings, especially under the influence of abrasive fluids.

[0029] A continuous, tubular closed cooling duct can advantageously be provided which extends from the high pressure region (preferably from the free front end of the screw conveyor) all the way to the magnetic coupling region, so that the higher pressure drives the pumped fluid from the high pressure region into the magnetic coupling region.

[0030] The pumped fluid is driven from the high-pressure area to the low-pressure magnetic coupling area by means of a cooling duct between the high-pressure area and the low-pressure magnetic coupling area, thereby generating a cooling flow and / or a cleaning flow by means of the rotor, which prevents the magnetic coupling from overheating and thus extends the service life of the eccentric screw pump.

[0031] The cooling ducts can, for example, pass through the entire rotor, including the pump drive shaft, the drive train and the screw conveyor, along an axis of symmetry (for example along a central longitudinal axis in the region of the screw conveyor, which is not necessarily straight), wherein the cooling ducts are produced by means of conventional drilling methods through the entire rotor or by using a 3D printing method. In the case of a 3D printing method, the entire rotor with the cooling ducts therein is printed out by means of a 3D printer, wherein the material used for printing is sintered after printing to produce the rotor according to the invention.

[0032] The bearing support or the drive region can advantageously have at least one connection, via which the auxiliary fluid can be introduced. The bearing support or the drive region preferably has at least one further connection, via which the auxiliary fluid can be discharged again.

[0033] Thus, an auxiliary fluid can be introduced into the drive region and discharged by means of these two connectors. The auxiliary fluid can be, for example, a fluid for flushing and cleaning the bearing seat or the drive region and the magnetic coupling, wherein, for example, when replacing the pumping fluid or during maintenance operations, the fluid for flushing and cleaning is introduced by means of the first connector and discharged by means of the second connector. For example, it may be necessary to flush the drive region to prevent the pumping fluid from generating strong deposits in the drive region. Alternatively, the auxiliary fluid can also be an additional fluid for cooling in order to additionally cool the drive region and the magnetic coupling. If longer system downtimes occur when pumping chemically corrosive fluids, the auxiliary fluid can also be a neutralizer, which is introduced into the drive region to neutralize the chemically corrosive pumping fluid remaining in the drive region, thereby preventing damage caused by the fluid.

[0034] Advantageously, the region of the bearing seat conducting the auxiliary fluid can be separated from the region conducting the fluid to be pumped by means of a contact seal.

[0035] The area with the auxiliary fluid is thus separated from the area with the fluid to be pumped by means of the contact seal. This is particularly advantageous when toxic, abrasive or highly toxic products are pumped as the fluid to be pumped. The contact seal can be realized in the form of a slide ring seal. In most cases, the slide ring seal has small leaks or seepages, respectively, so that only small leaks of the fluid to be pumped need to be discharged by means of a flushing fluid, which itself is non-abrasive and non-toxic.

[0036] Advantageously, an auxiliary fluid can be supplied to the bearing seat or the drive region, respectively, and / or can be guided therein, in order to clean the bearing seat or the drive region without disassembly.

[0037] The drive region can thus be cleaned with the aid of an auxiliary fluid for flushing without having to dismantle the eccentric screw pump.

[0038] Another object of the invention is to provide an eccentric screw pump with a screw conveyor which is driven in rotation by the motor drive shaft of the motor and thereby rotates in the screw lead of the stator in a rotary oscillating manner. The screw conveyor is thus directly connected to the pump-side half-coupling and cooperates with the motor-side half-coupling, wherein the two half-couplings are connected to each other in a torque-transmitting manner by means of magnetic forces across an air gap (in the above sense) which permanently separates them, and the air gap is formed and dimensioned so that it preferably withstands the rotary oscillating movements applied by the screw conveyor to the pump-side half-coupling in a contactless manner.

[0039] The advantage of this type of eccentric screw pump is that the screw conveyor is directly connected to the pump-side coupling half, so there is no need for a drive train and plain or rolling bearings in the bearing housing to accommodate the rotary oscillating movement of the screw conveyor. As a result, the eccentric screw pump can be realized more compactly.

[0040] The air gap between the two coupling halves is formed and dimensioned so that it can withstand the rotary oscillating motion of the screw conveyor. The eccentricity of the rotary oscillating motion is therefore smaller than the width of the air gap, so that no contact and no friction occurs between the two coupling halves and the seal - this can again be achieved, for example, in the form of a cylindrical air separator between the coupling halves.

[0041] Another advantage of this eccentric screw pump is that the magnetic coupling and its non-contacting nature allow for a completely new drive concept, since it is no longer necessary to connect the motor drive shaft to the oscillating screw conveyor in order for the motor drive shaft to run completely smoothly.

[0042] In the case of this variant, the air gap can preferably also be penetrated by a seal which seals the motor region from the rest of the eccentric screw pump (preferably in a contact-free manner).

[0043] The motor region is thus sealed so that the fluid to be pumped cannot enter the motor region, thereby preventing possible damage.

[0044] This variant of an eccentric screw pump can preferably include the features of the eccentric screw pump first described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be described based on the following drawings:

[0046] Figure 1 A schematic diagram of an eccentric screw pump is shown;

[0047] Figure 2 Shows Figure 1 A cross-sectional view of an eccentric screw pump;

[0048] Figure 3 A cross-sectional view showing another embodiment of an eccentric screw pump according to the present invention;

[0049] Figure 4 A cross-sectional view of another embodiment according to the present invention is shown. DETAILED DESCRIPTION

[0050] Figure 1 A schematic diagram of an eccentric screw pump 1 is shown with a rotor 2 consisting of a pump drive shaft 5 which rotates substantially about a fixed axis relative to a stator 3 in a bearing housing 4. The pump drive shaft 5 is driven in rotation by a motor drive shaft 6 of a motor 7. The pump drive shaft 5 is connected via a transmission 8 to a screw conveyor 9 which rotates in a screw lead 10 of the stator 3 in a rotationally oscillating manner.

[0051] The drive train 8 thus provides the screw conveyor 9 with its driving torque. The drive train 8 has the function of compensating for differences in the motion sequences of the screw conveyor 9 and the pump drive shaft 5.

[0052] There is a gap, referred to as an air gap 11, between the motor drive shaft 6 and the pump drive shaft 5. The motor drive shaft 6 thus supports a motor-side half coupling 12, while the pump drive shaft 5 supports a pump-side half coupling 13, which are connected to one another in a torque-transmitting manner by means of magnetic forces through the air gap 11. The gap, referred to as the air gap 11, is penetrated by a seal 14, which separates a motor region 15 of the motor 7 from the rest of the eccentric screw pump 1.

[0053] The seal 14 is implemented as a cylindrical air separator tank, the open side of which is held on the bearing seat. The cylindrical air separator tank forms a cavity, which protrudes beyond the bearing seat and receives the pump-side half coupling 13. The air separator tank thus enlarges the installation space formed by the bearing seat.

[0054] The motor-side coupling half 12 and the pump-side coupling half 13 are designed and magnetically mounted in such a way that they rotate synchronously with one another during trouble-free operation of the eccentric screw pump 1 .

[0055] A thermal sensor 16 or another slip detector is provided to detect slip between the two coupling halves 12 and 13. If such slip occurs, an alarm can be triggered and / or slip-terminating measures can be additionally initiated.

[0056] The eccentric screw pump 1 has a continuous tubular closed cooling duct 17, which extends from a first region 18 with high pressure to a second region 19 of the magnetic coupling with lower pressure, so that the higher pressure drives the pumping fluid from the first region with high pressure into the second region of the magnetic coupling with lower pressure. A cooling flow and / or a cleaning flow is thus generated. The cooling duct 17 is shown in dashed lines.

[0057] Figure 2 Shows Figure 1 1, further comprising a centrifugal pump wheel 20, which serves as a pump device and drives the flow of the pumped fluid via the air gap 11. The pump-side coupling half 13 can thus be cooled by means of the pumped fluid.

[0058] The pump drive shaft 5 is preferably supported on a first rolling bearing 21 and a second rolling bearing 22 , wherein the rolling bearings 21 and 22 can be designed as ceramic bearings, thereby increasing the service life and reducing the maintenance effort compared to metal bearings.

[0059] Arranged in the drive region 23 are a first connection 24 , via which auxiliary fluid can be introduced, and a second connection 25 , via which the auxiliary fluid can be discharged again for a cleaning process. The drive region can thus be cleaned without disassembly.

[0060] The two connections 24 and 25 can also be used to suck in pumped fluid in the drive region in order to create an additional cooling flow.

[0061] Figure 3 A cross section is shown of a further embodiment of an eccentric screw pump 1 according to the invention, which has a conveying screw 9 which is driven in rotation by the motor drive shaft 6 of the motor and thus rotates in a screw lead 10 of the stator 3 in a rotationally oscillating manner.

[0062] The screw conveyor 9 is thus directly connected to the pump-side half-coupling 13 without a drive train or another intermediate component, for example acting as a universal joint, to ensure movement regulation. This intermediate component cooperates with the motor-side half-coupling 12 .

[0063] In view of the above, the two coupling halves 12 and 13 are connected to each other in a torque-transmitting manner by means of magnetic forces across an air gap 11 (according to the above definition) which continuously separates them. As a result, the air gap 11 is formed and dimensioned so that it can withstand the rotary oscillating movement imposed by the screw conveyor 9 on the pump-side coupling half 13. The eccentricity of the rotary oscillating movement is therefore smaller than the width of the air gap 11, so that the air gap does not locally drop to "zero" situation.

[0064] The air gap is preferably penetrated by a seal 14 in the form of a cylindrical air separation pot. The motor region is then sealed off from the rest of the eccentric screw pump 1 .

[0065] Figure 4 A further exemplary embodiment according to the invention is also shown in cross section, wherein a preferred arrangement of the individual components can be seen in the cross section of all components.

[0066] Reference numerals list

[0067] 1 Eccentric screw pump

[0068] 2 Rotors

[0069] 3. Stator

[0070] 4 Bearing seat

[0071] 5 Pump drive shaft

[0072] 6 Motor drive shaft

[0073] 7 Motor

[0074] 8 Powertrain

[0075] 9 Screw conveyor

[0076] 10 Screw lead

[0077] 11 Air Gap

[0078] 12 Motor side coupling half

[0079] 13 Pump side half coupling

[0080] 14 Seals

[0081] 15 Motor area

[0082] 16 Thermal Sensor

[0083] 17 Cooling pipe

[0084] 18 The first region with high pressure

[0085] 19 Second region with low pressure

[0086] 20 Centrifugal pump impeller

[0087] 21 First rolling bearing

[0088] 22 Second rolling bearing

[0089] 23 Drive area

[0090] 24 First connecting piece

[0091] 25 Second connecting piece

Claims

1. An eccentric screw pump (1) comprising a rotor (2), a transmission (8) and a screw conveyor (9), wherein the rotor (2) consists of a pump drive shaft (5) which rotates substantially about a fixed axis relative to a stator (3) in a bearing housing (4), the pump drive shaft being driven in rotation by a motor drive shaft (6) of a motor (7), the screw conveyor (9) rotating in a rotationally oscillating manner on the screw lead (10) of the stator (3), wherein the transmission (8) provides the screw conveyor (9) with its drive torque, the transmission (8) balancing the differences in the motion processes of the screw conveyor (9) and the pump drive shaft (5), characterized in that An air gap (11) is present between the motor drive shaft (6) and the pump drive shaft (5), and the motor drive shaft (6) supports a motor-side half coupling (12), and the pump drive shaft (5) supports a pump-side half coupling (13), wherein the motor-side half coupling (12) and the pump-side half coupling (13) are connected to each other in a torque-transmitting manner through the air gap (11) by means of magnetic force, wherein the air gap (11) is penetrated by a seal (14), which seals the motor area (15) from the rest of the eccentric screw pump (1) in a sealed manner.

2. The eccentric screw pump (1) according to claim 1, characterized in that: The seal (14) is preferably implemented as a cylindrical air separation tank, the open side of which is held on the bearing seat (4) and forms a cavity, which protrudes beyond the bearing seat (4) and receives the pump-side half coupling (13).

3. The eccentric screw pump (1) according to claim 1 or 2, characterized in that: The motor-side coupling half (12) and the pump-side coupling half (13) are designed and magnetically equipped in such a way that they rotate synchronously with one another during interference-free operation of the eccentric screw pump (1).

4. The eccentric screw pump (1) according to claim 3, characterized in that: The eccentric screw pump (1) comprises a thermal sensor (16) or another slip detector which triggers an alarm and / or takes slip-terminating measures as soon as slip occurs between the half-couplings (12, 13).

5. An eccentric screw pump (1) according to any one of the preceding claims, characterized in that The pump-side half coupling (13) is cooled by the fluid pumped by the eccentric screw pump (1).

6. The eccentric screw pump (1) according to claim 5, characterized in that: The pump drive shaft (5) preferably supports a pump device on its front end region facing away from the screw conveyor (9), the pump device preferably being a pump wheel, ideally a centrifugal pump wheel (20), which drives the fluid through the air gap (11).

7. The eccentric screw pump (1) according to claim 5 or 6, characterized in that: The pump drive shaft (5) is supported on rolling bearings (21, 22).

8. The eccentric screw pump (1) according to any one of claims 5 to 7, characterized in that: A continuous, tubular closed cooling duct (17) is provided, which extends from a high-pressure region (18) to a low-pressure region (19) of the two half-couplings (12, 13) of the magnetic coupling, so that a higher pressure drives the pumped fluid from the high-pressure region (18) into the region (19) of the magnetic coupling.

9. An eccentric screw pump (1) according to any one of the preceding claims, characterized in that The bearing seat (4) or the drive area (23) has at least one connection piece (24) through which an auxiliary fluid can be introduced, and the bearing seat (4) or the drive area (23) preferably has at least one further connection piece (25) through which the auxiliary fluid can be discharged again.

10. The eccentric screw pump (1) according to claim 9, characterized in that: The area of ​​the bearing seat (4) that conducts the auxiliary fluid is separated from the area that conducts the fluid to be pumped by means of a contact seal.

11. The eccentric screw pump (1) according to claim 9 or 10, characterized in that: The auxiliary fluid is supplied to the bearing seat (4) or the drive region (23) and / or is guided therein so that the bearing seat (4) or the drive region (23) can be cleaned without disassembly.

12. An eccentric screw pump (1) preferably but not exclusively according to any of the preceding claims, having a screw conveyor (9) which is rotationally driven by a motor drive shaft (6) of a motor (7) and thereby rotates in a rotationally oscillating manner in a screw lead (10) of a stator (3), characterized in that: The screw conveyor (9) is directly connected to the pump-side half coupling (13) and cooperates with the motor-side half coupling (12), wherein the two half couplings (12, 13) are connected to each other in a torque-transmitting manner by means of magnetic forces across an air gap (11) that continuously separates them, and the air gap (11) is formed and dimensioned so that it can withstand the rotary oscillating movements imposed by the screw conveyor (9) on the pump-side half coupling (13).

13. The eccentric screw pump (1) according to claim 12, characterized in that: The air gap (11) is penetrated by a seal (14) which seals the motor region (15) from the rest of the eccentric screw pump (1) in a sealing manner.

14. The eccentric screw pump (1) according to claim 12 or 13, characterized in that: The eccentric screw pump (1) has the features of one or more of the dependent claims 2 to 11.

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