EP3568596A1

EP3568596A1 - Controlling the gap geometry in an eccentric screw pump

Info

Publication number: EP3568596A1
Application number: EP18701291.9A
Authority: EP
Inventors: Paul Krampe; Michael ROLFES
Original assignee: Vogelsang GmbH and Co KG
Current assignee: Vogelsang GmbH and Co KG
Priority date: 2017-01-16
Filing date: 2018-01-16
Publication date: 2019-11-20
Anticipated expiration: 2038-01-16
Also published as: EP4137698A1; WO2018130718A1; EP3568596B1; DE102017100715A1; BR112019014558A2; KR102356133B1; BR112019014558B1; PL3568596T3; US11286928B2; JP7015839B2; CN113107835B; CA3050182A1; CN110392785B; AU2018208543B2; KR20190105632A; EP3568596C0; CN110392785A; CN113107835A; US20200124046A1; JP2020504266A

Abstract

The invention relates to an eccentric screw pump (1) for delivering liquids loaded with solids, having a rotor (4) wound helically, a stator (2), having an inlet (10) and an outlet (12), in which the rotor (4) is rotatably arranged about a longitudinal axis (L₁) of the stator, and which has a screw-like inner wall (8) corresponding to the rotor (4), wherein the rotor has a form tapering toward the outlet (12) or the inlet (10), preferably a conical form and/or a varying eccentricity (e₁, e₂), and wherein rotor (4) and stator (2) are arranged relative to each other and formed such that at least one chamber (5) is formed, which is used for conveying the liquid, and the chamber is separated off by a narrowing (7) in particular a sealing line (D). The invention is characterized by an adjusting device for adjusting an axial relative position of rotor (4) and stator (2), wherein the adjusting device (39) is designed to widen the narrowing (7) between rotor (4) and stator (2).

Description

Control of the gap geometry in an eccentric screw pump

The invention relates to an eccentric screw pump for conveying solids laden liquids, with a helically wound rotor, a conical stator, with an inlet and an outlet, in which the rotor is arranged rotatably about a longitudinal axis of the stator, and one corresponding to the rotor helical inner wall, wherein the rotor has a tapered to the outlet or inlet, preferably conical, shape and / or a varying eccentricity and wherein the rotor and stator are arranged and configured such that at least one chamber is formed, which is for conveying the fluid is used, and the chamber is separated by a constriction, in particular sealing line. The invention further relates to a method for operating such an eccentric screw pump.

Eccentric screw pumps of the aforementioned type have been known for some years and are used in particular to gently convey and meter liquids laden with solids, abrasive liquids, or liquids of high viscosity in general. They use a single or multi-start helical rotor, which is arranged in a corresponding two- or multi-pass chamber of a stator and rotates in this. In an eccentric screw pump, the screw is rotated about a screw rotation axis, which in turn rotates about a stator longitudinal axis which is generally parallel to it, which is guided eccentrically on a circular path. The drive of the screw of an eccentric screw pump is frequently effected by a wobble shaft, which is formed by a shaft provided with universal joints at both ends between the drive motor and the rotor. Corresponding design of the outer profile of the rotor and of the inner profile of the stator results in a constriction, in particular a sealing line, which seals the at least one chamber, but preferably individual chambers of a plurality of chambers, against each other and the rotor and the stator can be in direct contact with one another and In this case, the rotor is designed as a single-flighted screw and the stator as a double-flighted screw with a double pitch, which results in the sealing of the individual chambers.

From DE2632716 a screw pump is previously known, which has a conical screw and a conical pressure jacket. In this embodiment, the screw has a conicity of about 30 ° cone angle, whereby an increase of the delivery pressure over a short screw length should be achieved. Screw and pressure jacket are axially movable relative to each other by the pressure jacket is guided axially movable in a sleeve. As a result, a pressure is to be kept constant by the pressure shell is moved under the action of the liquid pressure on a ring portion of the pressure jacket in the pump. But systematically can only cause a vertical delivery and thus pressing the pressure jacket to the worm by an increase in pressure at the output. A disadvantage of this prior art system is that it should be designed in the objective solely on the constancy of the increased pressure, which is generated by the cross-sectional area reduction in the conveying direction of the conical pump gap and allows no axial displacement in dependency of other factors.

From AT223042 a screw pump is also previously known, which has a conical stator and rotor. By means of a screw sleeve inserted between the rotor and the output shaft, the rotor can be adjusted axially with respect to the stator in this screw pump by a user while the pump is stopped by a hand hole, the sleeve manually by means of a tool rotated. As a result, both a clamping and too large a gap between the stator and the rotor, caused by a swelling of the stator or a wear of the rotor and / or stator, are compensated. From DE1020151 12248A1 an eccentric screw pump is previously known, in which the gap geometry between the rotor and stator is variable by the bias of the stator is readjusted. Increased prestressing causes a compression of the stator designed as an elastomer part and can thereby reduce the gap geometry. A disadvantage of this eccentric screw pump, however, is that the elastomer thicknesses of the stator are different both in the circumferential direction and in the longitudinal direction due to its geometry and therefore leads to an increased bias to uneven elastic deformation. A reliable operation of the eccentric screw pump is therefore not guaranteed and by the non-uniform gap geometry, with this adjustment locally increased wear can be generated.

In progressing cavity pumps conical progressing cavity pumps are also known because they allow both a simple assembly and an adjustment of the rotor with respect to the stator in case of wear. Such an eccentric screw pump is known, for example, from WO 2010/100134 A2. In order to prevent wear, this document proposes an eccentric screw pump with a conical rotor, which is designed in such a way that the individual chambers all have the same volume. Wear phenomena, in particular so-called cavitations, then form during operation, it is possible to axially displace the rotor in relation to the stator such that the chamber volumes are again of the same size and tightness is achieved.

A disadvantage of these known solutions is that these solutions alone can compensate for already occurring wear on the stator by the rotor is moved. The occurrence of wear as such can not prevent the screw pump and progressing cavity pump known in the art.

It is therefore an object of the present invention to provide an eccentric screw pump of the type mentioned, which not only reduces the compensation of incurred wear, but already reduces the formation of wear and thus increases the life of the eccentric screw pump and reduces maintenance. This object is achieved in an eccentric screw pump of the type mentioned in that it has an adjusting device for adjusting an axial relative position of the rotor and stator, which is designed to the gap geometry between see how to optimize rotor and stator by setting up the constriction between rotor and stator.

The invention is based on the finding that the gap geometry, ie the geometry of the constriction separating the chamber (s), is important on the one hand to make the seal sufficiently so that pumping is possible, while on the other hand friction prevails during operation of the eccentric screw pump , whereby the individual parts, in particular rotor and stator heat and due to the material expansion then a bias voltage between the rotor and stator is increased, or the constriction is too small. The increased bias then leads to further wear. The invention has recognized that any wear can be avoided, or reduced, if the constriction is widened during operation and the gap geometry can thus be adapted to the operating conditions and thus optimized. Therefore, the present invention proposes an adjusting device which is designed to widen the constriction between rotor and stator. If the constriction is widened again, there is a contact with less bias or no contact, and thus less friction between the rotor and stator, which in turn leads to less wear. When pumping liquid, there is also a cooling effect, so that with reduced preload the parts can cool down again. As a result, it is also possible, for example, to set a larger gap during a startup of the eccentric screw pump, in order to keep the friction low in the dry state. It is also possible to operate the eccentric screw pump energy-saving, by adjusting to the optimum overall efficiency, taking into account the volumetric efficiency and the friction losses. However, only a small enlargement of the narrowing is suitable for shear-sensitive media. By virtue of the invention, the eccentric screw pump can thus be adjusted to the respectively conveyed media.

The rotor has a tapered shape towards the outlet or inlet. The shape is determined by the envelope that encloses the rotor. The mold is preferably conical. The rotor thus has a diameter which becomes smaller in the direction of the outlet or the inlet. Preferably, the rotor tapers linearly. However, it is also preferred that the rotor has a shape tapering according to a predetermined function, for example a function of the 2nd, 3rd or 4th degree. The diameter then decreases progressively or degressively. This has advantages depending on the load of the rotor to avoid excessive wear. The choice of whether the rotor tapers to the inlet or outlet is particularly dependent on structural frame conditions, and should be based on the type of installation. The direction of the taper determines the direction in which the rotor is inserted into the stator.

Alternatively or additionally, the rotor has an eccentricity that changes in the direction of the inlet or the outlet. The eccentricity preferably varies linearly, i. increases or decreases linearly. However, it is also preferred for the rotor to have an eccentricity which varies according to a predetermined function, for example a function of the second, third or fourth degree. The eccentricity then decreases progressively or degressively. The stator is adapted in both cases to the rotor and thus has a corresponding inner contour.

In principle, it is preferred that the taper and / or the longitudinally varying eccentricity of the rotor in the conveying direction is so small that as a result no appreciable reduction of the gap cross section in the conveying direction is effected in order to avoid undesired pressure increase. This can be achieved, for example, by selecting the taper such that two straight lines averaging the envelope in a longitudinal section form a cone angle of less than 20 °, preferably less than 10 ° and in particular less than 5 ° to each other. In particular, it is preferable that the area difference between the gap cross-sectional area in the outlet of the stator and the gap cross-sectional area in the inlet of the stator caused by the taper is less than 10%, preferably less than 5% of the gap cross-sectional area in the inlet of the stator.

Even with a changing eccentricity at a constant diameter, it is possible to extend a constriction by an axial displacement. A portion of the rotor with smaller eccentricity can thus be brought into a portion of the stator with greater eccentricity, whereby the constriction is widened. Also, a combination of a tapered rotor and a rotor with varying eccentricity is preferred.

In a preferred embodiment, the adjusting device is adapted to expand the constriction between the rotor and stator so far that a leakage gap between the rotor and stator is formed. In this case, constriction is not formed by a contact between the rotor and stator, but by a small gap, the Leakage gap, which still provides a certain seal. In this case, although the delivery rate decreases, due to the lack of physical contact between the rotor and stator and the fluid film between these parts, further cooling takes place and wear is further reduced. It can be provided that such a leakage gap is not permanently present during operation, but is only adjusted during or after special loads.

Furthermore, it is preferred that the adjusting device is adapted to perform the expansion of the constriction in dependence on one or more predetermined operating parameters. It is conceivable, for example, that an extension of the contraction is set automatically after a certain period of operation. It is also conceivable to measure the power consumption of a drive motor and, with increasing power consumption, to expand the constriction. Preferably, the expansion of the constriction takes place as a function of a plurality of operating parameters. While it is also conceivable and preferable to use only a single operating parameter, wear can be more effectively reduced by the use of multiple operating parameters.

Particularly preferred is one of the operating parameters, the temperatures of the stator and / or the rotor. Preferably, the temperature of the stator is measured. For this purpose, the eccentric screw pump preferably has at least one sensor, which is arranged in or on the stator and measures the temperature of the stator. Preferably, the temperature is measured at several points so as to be able to reduce wear particularly effectively. Preferably, a continuous expansion of the constriction takes place as a function of the temperature. Alternatively, one or more threshold values are predetermined, and when the one or more threshold values are exceeded, a stepwise expansion of the constriction is performed.

Preferably, one, in particular another of the operating parameters, is the delivered liquid volume. Preferably, the delivered volume of liquid is the volume of liquid per revolution. If the delivered volume of liquid per revolution decreases, this means that more gas or air is being pumped. When delivering gas or air, the cooling effect that the medium exerts on the eccentric screw pump is less than when a liquid is conveyed. Therefore, it is preferable in this case also to expand the constriction to prevent wear. For this purpose, it is conceivable that a flow meter is arranged at the inlet or the outlet of the stator. According to another preferred embodiment, one of the operating parameters is a liquid level at the inlet of the stator. For this purpose, a liquid sensor or a plurality of liquid sensors are preferably provided. It may be preferable to measure only a certain fill level as a threshold. Alternatively, a continuous measurement of the filling level at the stator inlet is preferred. If there is a low liquid level at the stator inlet, the likelihood that the eccentric screw pump will run dry is higher, as a result of which the friction is higher and the cooling of the eccentric screw pump is lower. This in turn leads to a faster heating and thus material expansion, which further reduces the constriction, and can increase preload. Therefore, it is preferable that in the case that a low liquid level is measured at the inlet of the stator, the constriction between the rotor and stator is widened.

Another conceivable parameter is the pressure at the outlet. If this remains the same or decreases, while increasing the torque, this is an indicator of increased friction between the rotor and stator and thus a sign for a swelling of the stator material. Even in such a case, it is preferable to expand the constriction in order to adapt the gap geometry to the changed framework conditions.

In a further preferred embodiment, the stator is mounted so as to be axially displaceable and the adjusting device is arranged to displace the stator axially, in order at least partially to widen the constriction between rotor and stator. The rotor is usually coupled to a drive and the stator is fixedly mounted in the direction of rotation. When worn, the stator must first be replaced, since it is usually made of a softer material than the rotor. For this reason, since the stator must be easily interchangeable, it is proposed in this embodiment to mount the stator in such a way that it is axially displaceable so as to at least partially widen the constriction between rotor and stator. For this purpose, the adjusting device is preferably coupled to the stator in order to move it. The adjusting device can be coupled to a designated drive of the stator. Such a drive of the stator is formed in a preferred embodiment as a hydraulic drive, rack and pinion drive, chain drive, spindle drive or the like. Preferably, the drive of the stator is designed so that an axial position of the stator can be maintained. This is preferably realized in that the drive of the stator is self-locking. In a further preferred embodiment, the rotor is mounted so as to be axially displaceable and the adjusting device is set up to axially displace the rotor in order to at least partially widen the constriction between the rotor and the stator. It should be understood that a combination of the two displacements is possible and preferred, so that both rotor and stator are axially displaced. This makes it possible to keep the absolute ways of shifting small.

In a variant, a drive train, comprising a drive motor and a drive shaft, of the rotor is displaceable together with the rotor. The rotor is usually coupled by means of a shaft to a drive motor, which is usually designed as an electric motor. Since the rotor rotates eccentrically about a central axis of the stator, so its central axis describes a circular path around the central axis of the stator, such a drive shaft usually also includes at least one universal joint or bending rod to allow an eccentric torque transmission. In this embodiment, both the drive motor and the drive shaft, which belong to the drive train, are mounted displaceably together with the rotor. As a result, the construction of the drive train is simplified and, for example, a linear bearing is provided for the drive motor, which, as described above with respect to the stator, can be provided with a drive provided for this purpose.

In a further variant, which may also be designed in addition to the variant described above, the rotor together with the drive shaft is displaceable relative to the drive motor. In this variant, it is preferred that between the drive shaft and the drive motor, a transmission is arranged, which allows an axial displacement of the drive shaft. For example, gears of the transmission are designed so that an axial displacement is allowed. In this variant, the arrangement of the drive motor is simplified, while the construction of the transmission is more complicated than that described in the previous embodiment. However, a further advantage results from the fact that the mass of the displaceable parts is lower. Furthermore, it is possible to store the drive motor separately.

In a variant, or in addition thereto, the drive shaft is formed at least in two parts and has an expansion member, which allows an extension and shortening of the drive shaft for axial displacement of the rotor. The drive shaft may be formed telescopically in this embodiment and automatically exert the extension, or for the rotor, a separate drive for moving the rotor is provided. For example, it is conceivable that in the drive shaft a hydraulically operated Nes expansion member is arranged, which allows an axial adjustment by application of hydraulic pressure. As an alternative to a hydraulic expansion element, it is also possible to provide a mechanically acting expansion element, for example in the sense of a spindle drive. Alternatively or additionally, a separate drive unit for the rotor is provided, which axially displaces the rotor, while the expansion member is passive and allows this displacement. As a result, the construction is further simplified.

According to another preferred embodiment, the longitudinal axis of the stator is substantially vertically aligned in operation and the outlet of the stator is located at the top. This results in further advantages. On the one hand, the narrowing or bias between the rotor and the stator is not narrowed or increased in the lower stator region by the additional weight of the rotor. Another advantage results from the fact that when changing the gap geometry up to a leakage gap, liquid flows back downwards, in the direction of the inlet, and so an additional cooling effect is achieved. It is particularly advantageous in this variant that if not only liquid but also gas is conveyed, the liquid is always present in the region of the contact points, that is to say in the region of the sealing line, and thus always cooling the sealing line even when conveying a high proportion of gas is guaranteed. As a result, heating and thus an increase in the friction and the preload, or an excessive reduction of the constriction is effectively avoided. This prevents further wear. The vertical arrangement is also space-saving and the eccentric screw pump can be very easily installed in existing systems. The vertical arrangement is made possible by the fact that the constriction can be extended.

In a further preferred embodiment, the stator is formed at least in the region of the inner wall of a resilient material, in particular an elastomer. As a result, on the one hand, the manufacture of the stator is simplified, on the other hand also produces a good seal between the stator and rotor. In a variant it can be provided that the inner wall of the stator is covered with a substantially uniformly thick layer of elastomeric material. In another variant, the entire stator is formed of elastomeric material and externally provided with a cuff for stabilization.

According to a further preferred embodiment, it is provided that the adjusting device is designed to project the constriction between rotor and stator Start of a start-up operation or to expand during or after a spouting operation of a drive motor to rotate the rotor, and to reduce the constriction between the rotor and stator before starting during the startup of the drive motor. According to this embodiment, the constriction between the rotor and stator in the course of the start of a conveying operation of the eccentric screw pump, so at start-up or after the start of a drive motor which generates the rotational movement of the rotor relative to the stator, adjusted by an expanded constriction to an elongated constriction. As a result, the eccentric screw pump is adjusted from an initially high internal leakage current to a reduced leakage current. This adjustment serves to abruptly build up the delivery volume and / or the delivery pressure of the eccentric screw pump when starting the delivery process, which would cause a high load on the eccentric screw pump and the connected lines, but continuously build up over a start period. This starting period can be in the range of one second to several seconds. In particular, this embodiment is advantageous when a drive motor is used which has no controlled via a frequency converter speed control, but instead has an immediate increase to rated speed when starting.

In principle, it should be understood that, for the purpose of this regulation, the constriction between the stator and the rotor can each be extended at the end of a conveying process, so that it is in an expanded state during a subsequent start of a conveying process or before the starting of the conveying process a corresponding extension of the constriction is carried out in order to then start this drive motor after carrying out this expansion. In both ways it can be ensured that, when the drive motor is started, there is no reduced constriction or even direct sealing contact between the stator and the rotor, which would cause a high delivery volume and a high delivery pressure from the beginning and would immediately cause.

Still further, it is preferable if the adjusting device has an input interface for receiving a pressure signal and is designed to expand or reduce the constriction between rotor and stator in dependence on the pressure signal. According to this development, the adjusting device is basically a corresponding control unit, which may be designed as an electronic control unit, may have, designed to perform a change in the constriction between the rotor and stator in response to a pressure signal. The pressure signal can be a pressure on the input side, a pressure inside the stator or a pressure on the output side. be side of the stator, so in particular also a pressure-side pressure of the eccentric screw pump. In this way, an exact setting of a pressure can be carried out, it can also be a predetermined pressure profile adjusted by adjusting the constriction as actual value. This setting or adjustment is inventively by extending or reducing the extension between the rotor and stator, which allows a much more precise, spontaneous and low-inertia adjustment or adjustment compared to a possible also possible regulation of the speed of the rotor and stator. In particular, this embodiment can also be used to provide an overpressure protection. In this case, upon reaching a certain pressure or exceeding the specific pressure, the constriction between the rotor and the stator is widened, thereby preventing an increase in pressure above a certain maximum pressure.

Furthermore, the eccentric screw pump according to the invention can be further developed in that the adjusting device has an input interface for receiving a volume quantity signal and is designed to expand the constriction between the rotor and stator in dependence of the volume flow signal such that at a value of the volume signal that indicates that a Since the beginning of a delivery process volume delivered corresponds to a desired volume, the constriction between the rotor and stator is extended such that no further promotion of a volume from the outlet of the stator takes place more. According to this embodiment, the adjusting device is configured to receive a volume-quantity signal. In principle, this volume quantity signal can characterize a nominal volume that is to be conveyed by the eccentric screw pump. This means that from the beginning to the end of a continuous delivery process, ie a continuous operation of the eccentric screw pump, a certain volume to be promoted by the eccentric screw pump. Basically, the inventors have recognized that such exact metering of a given delivery rate due to inertia and caster effects can not be achieved in a sufficiently accurate manner by controlling and regulating the drive motor that drives the rotor. According to the invention, the constriction between the rotor and the stator is instead adjusted in such a way that the exact dosage can be adjusted or regulated thereby. This means, in particular, that upon reaching the desired volume quantity, that is to say the volume setpoint, the constriction of such a type is widened that no further volume is conveyed by the eccentric screw pump. In particular, the adjustment or adjustment of the constriction between the rotor and stator of such a type can take place, that then, if only a small proportion of the desired setpoint volume to promote is an extension of the constriction between the rotor and stator is set and in this way the flow rate in one or two stages or continuously reduced. The actual value volume can be detected here by a corresponding volume flow meter or can be computationally calculated from the number of revolutions of the eccentric screw pump and the degree of constriction between the rotor and stator over the delivery period. As a volume quantity signal, a desired value signal can be detected by the adjusting device or entered into the adjusting device, in this case, the calculation of the manipulated variable for the constriction between the rotor and stator within the adjusting device and can be carried out by internal calculation or additional input of actual values in the adjusting device become. The volume quantity signal may also be a difference signal which has been determined from the setpoint value and the actual value, in order to allow directly from this a manipulated variable calculation within the adjustment device. It is further preferred that the adjusting device is designed to adjust the axial relative position of the rotor to the stator, while the rotor rotates relative to the stator. This embodiment for axial adjustment during operation of the pump can be realized, for example, by an externally accessible or externally controllable adjusting device. The adjusting device can be designed as an energy-operated actuator and thus enable the adjustment during the rotation of the rotor, for example by a hydraulically, pneumatically or electrically operated actuator is provided on the pump for the axial displacement between the rotor and stator.

According to a second aspect of the invention, the object mentioned is achieved by a method for operating a progressing cavity pump according to at least one of the above-described preferred embodiments of an eccentric screw pump according to the first aspect of the invention, comprising the steps of: driving the rotor to convey a liquid; Extending the constriction between rotor and stator by relative axial displacement of rotor and stator to each other. It should be understood that the progressive cavity pump according to a first aspect of the invention and the method according to the second aspect of the invention have the same and similar preferred embodiments, as set forth in particular in the subclaims. In this respect, reference is made in full to the above description of the first aspect of the invention.

The method further preferably includes the step of adjusting a leakage gap between the rotor and the stator. The adjustment of the leakage gap is preferably carried out during the driving of the rotor for conveying a liquid. That is, that Moving the rotor and stator to each other, as well as the setting of a leakage gap preferably takes place during operation, namely, namely, when an operating parameter reaches or exceeds a threshold value.

Preferably, the method further comprises the step of: measuring a temperature of the rotor and / or the stator; and depending on the measured temperature, relative axial displacement of the rotor and stator. If, for example, a threshold temperature which is predetermined is exceeded, the rotor and stator are displaced axially relative to one another as a function of this exceeding, so that the constriction is widened. It can also be provided that with decreasing temperature, in turn, a reduction of the constriction, up to a contact under bias is performed so as to keep a leakage low. Preferably, the temperature of the rotor and / or the stator is permanently measured, preferably at predetermined small time intervals. Depending on these measurements, a displacement between the rotor and the stator is then preferably performed dynamically, so that the constriction present between the rotor and the stator and thus the gap geometry is always consistent with the measured temperature, so that wear can be prevented.

Preferably, the steps are further carried out: determining a liquid level at the inlet of the stator; and depending on the particular fluid level, relative axial displacement of the rotor and stator. The liquid level is preferably determined by means of a liquid sensor. It can be provided that the fluid level is determined only with respect to a certain threshold, for example half of the maximum inlet flow. Relative axial displacement of the rotor and stator, preferably by a predetermined fixed value, is then carried out based on the determined fluid level. As a result, the constriction is widened, thereby preventing wear. It may also be provided that when the liquid level rises again, the constriction is reduced again, i. a small gap or contact is adjusted so as to achieve optimum gap geometry and delivery.

In a preferred further embodiment, the method further comprises: determining a delivered volume of fluid per revolution of the rotor; and, depending on the particular fluid volume, relative axial displacement of the rotor and stator. A small volume of fluid delivered per revolution of the rotor indicates that a relatively high proportion of gas is being delivered. A promotion of gas prevents the one hand, the lubrication between the touching parts, on the other hand, a cooling. In this case, when relatively much gas is being pumped and little Liquid per revolution of the rotor, it is preferred that the constriction is widened so as to prevent wear.

The method may be further developed by expanding the constriction between the rotor and the stator at the start of a startup of a drive motor for rotating the rotor, and reducing the constriction between the rotor and stator after the start of a startup of the drive motor. With this process development, a smooth start-up behavior is achieved with a non-sudden increase in delivery volume and delivery pressure. For the advantages, variants and aspects of this further development, reference is made to the above description of the embodiment of the eccentric screw pump corresponding thereto.

Further, it is preferable if a pressure is detected by means of a pressure sensor, and the constriction between the rotor and stator is expanded or reduced as a function of the pressure. With this embodiment of the method, an exact adjustment of a pressure, a pressure curve or the maintenance of a minimum pressure and / or a maximum pressure is achieved by the constriction between the rotor and stator is adjusted accordingly. This allows a spontaneous and accurate pressure control. For this purpose, reference is made to the corresponding corresponding embodiment of the eccentric screw pump and the above description.

Still further, it is preferable if a target volume amount is detected, and the constriction between the rotor and stator is extended or reduced depending on the target volume amount. According to this embodiment, the eccentric screw pump is controlled or regulated as an exact metering pump. For this purpose, a set volume amount is entered or taken by the eccentric screw and expanded or reduced the constriction between the rotor and stator as a function of this set volume. This extension or reduction of the constriction between the rotor and the stator is set such that upon reaching the target volume amount, the delivery volume is reduced to 0. This can be done by a corresponding expansion of the constriction or can be done in conjunction with such an extension and an end of the rotation of the rotor. In particular, can be carried out by a gradual or continuous expansion or narrowing an exact dosage to the desired target volume, if such an extension is carried out when only a small proportion of the target volume must be promoted to reach the target volume. Also to this embodiment reference is made to the above explanation of the corresponding embodiment of the eccentric screw pump.

The invention will be explained in more detail with reference to five embodiments with reference to the accompanying figures. Showing:

1 shows a schematic cross section through an eccentric screw pump according to a first embodiment;

FIG. 2a shows a schematic cross section through an eccentric screw pump along the longitudinal axis when the sealing line is set; FIG.

Fig. 2b shows a schematic cross-section perpendicular to the longitudinal axis according to

Figure 2a;

Fig. 2c is a schematic cross section perpendicular to the longitudinal axis according to

Figure 2a;

3a shows a schematic cross section through an eccentric screw pump along the longitudinal axis with the leakage gap set;

Fig. 3b shows a schematic cross section perpendicular to the longitudinal axis according to

FIG. 3a;

Fig. 3c is a schematic cross-section perpendicular to the longitudinal axis according to

FIG. 3a;

4 shows a schematic cross section through an eccentric screw pump according to a second embodiment;

5 shows a schematic cross section through an eccentric screw pump according to a third embodiment;

6 shows a schematic cross section through an eccentric screw pump according to a fourth embodiment; 7 shows a schematic cross section through an eccentric screw pump according to a fifth embodiment; and

8 is a flowchart of an embodiment of a method for

Operation of an eccentric screw pump. An eccentric screw pump 1 has a stator 2 and a rotor 4. The stator has a central axis L-ι, which extends centrally through an inner cavity 6 of the stator 2. The stator 2 has an inner wall 8, which limits the cavity 6 and is formed from an elastomeric material. The inner contour of the wall 8 is formed to define a double helix. The rotor 4 is also formed in an overall helical shape, wherein the pitch of the helical shape of the stator 2 has a double pitch with respect to the rotor 4. As a result, individual chambers 5, which are separated by a constriction 7, are formed.

The stator 2 further includes an inlet 10 and an outlet 12. The inlet 10 is connected to an inlet housing 14, which has an inlet flange 16 to which an inlet pipe 18 is flanged. The outlet 12 is further provided with an outlet housing 20 having an outlet flange 22 to which an outlet tube 24 is flanged.

Through the inlet housing 14 extends a drive shaft 26 which is connected via a first universal joint 28 with the rotor 4, and with a second universal joint 30 with an output shaft 32 of a transmission 34 is in communication. Instead of such a drive shaft 26 with two universal joints 28, 30, it is also preferable to use a thin bending wave, which allows the eccentric drive. The transmission 34 is connected on the input side to a drive motor 36, which is designed according to this embodiment as an electric motor. According to the invention, the eccentric screw pump 1 has an adjusting device 39 for widening the constriction 7 between the rotor 4 and the stator 2 in order to set an optimum gap geometry. According to this embodiment (FIG. 1), the adjusting device 39 is designed so that the stator 2 is mounted so as to be axially displaceable. The stator 2 is displaceable along the longitudinal axis L-ι, as indicated by the arrow 38. For this purpose, the stator 2 is received in portions of the inlet housing 14 and the outlet housing 20, which are sealed with a seal 40, 42. To move the Stators 2, the adjusting device 39 on an engagement portion 44, which may be in communication with a designated drive.

FIGS. 2 a, 2 b and 2 c as well as 3 a, 3 b and 3 c illustrate the change in the gap geometry, that is to say the widening of the constriction 7 on the basis of a schematic illustration. While FIGS. 2a-2c show a gap geometry with a sealing gap in which there is contact between rotor 4 and stator 2, FIGS. 3a-3c illustrate an enlargement of the constriction 7 so that a leakage gap S is set. Fig. 2b shows a section along the longitudinal axis L-ι, as shown in Fig. 1. The rotor 4 is in a maximum upper position with respect to Figs. 2a - 2c, which can be seen in particular with reference to FIGS. 2a and 2c, each showing sections perpendicular to the longitudinal axis L-i. FIG. 2 a shows a section near the inlet 10 and FIG. 2 c shows a section at the outlet 12. As can be seen in particular with reference to FIGS. 2 a and 2 c, the rotor 4 lies with a section of its peripheral surface 3 on an inner wall 9 of the stator 2 at. Due to the contact, a sealing line D is formed in the constriction 7. As a rule, it is provided that the rotor 4 is positioned axially in the stator 2 in such a way that a tension in the radial direction results. The stator 2 is formed of a flexible material such as in particular an elastomer. A bias in the radial direction thus leads to an elastic deformation of the stator 4 in the region of the sealing line D. Here, the friction is relatively high. High friction also leads to high wear. In operation, it may happen that this radial bias further increases, for example, due to swelling of the material of the stator 2 or due to expansion of the materials by heat input.

Even with shear-sensitive media, it is preferable, for example, to form a sealing line D and at the same time to achieve a relatively high radial prestress, so that medium is clearly separated at the sealing lines D between the chambers 5 and little shearing takes place.

By an axial adjustment of the overall conical rotor 4, it is possible to expand the constriction 7 and so to reduce a radial bias or even set a leakage gap S instead of a sealing line D. It should be understood that a leakage gap S also seals; the rotor 4 floats in this state on a liquid film in the constriction 7. The expansion of the constriction is achieved in that the rotor 4 is displaced in the direction of the conical enlargement is, that is, with reference to Figs. 2a - 3c to the left. As a result, the constriction 7 is widened, and a leakage gap S can form.

In the opposite case, it is also possible to reduce the constriction 7, that is, to narrow it further in order, for example, to remove a leakage gap S and to set a sealing line. This may be useful, for example, at high pressures. High pressures can cause the stator 2 is radially expanded and automatically sets a leakage gap S. In order to still obtain the optimum gap geometry, in such a case, an axial displacement in the direction of the conical constriction, that is, with reference to FIGS. 2a - 3c to the right, is required. The eccentricity e- ₁ , e ₂ is constant in this exemplary embodiment (FIGS. _{2 a} - ₃ c), while the diameter D ₁ , D _{2 of} the rotor 4 decreases in the direction of the outlet 12. That is, e- ₁ and e2 are identical while D- ₁ is greater than D2. However, embodiments are also encompassed in which the diameter is constant, ie D- ₁ is identical to D ₂ , and the eccentricity changes, ie, for example, that e- ₁ is greater than e ₂ . The effect of axial displacement is then appropriate.

Fig. 4 shows a comparison with FIG. 1 modified embodiment, wherein similar elements are designated by the same reference numerals. In this respect, reference is made in full to the above description of the first exemplary embodiment (FIG. 1). With regard to the geometry of the gap in the constriction 7, reference is made to FIGS. 2a to 3c.

In contrast to the first embodiment is in this embodiment (Fig. 4), the adjusting device 39 is formed so that the rotor 4 is axially displaceable, together with the complete drive train 25, according to this embodiment of the drive shaft 26, the gear 34 and the drive motor 36 consists. In this respect, the arrow 37 indicates that the drive motor 36 is also displaced. For this purpose, the housing 46 of the transmission 34 is displaceably mounted in a section 48 of the inlet housing 14 opposite the inlet 10 of the stator 2 and is sealed from the environment by a seal 50.

For displacing the rotor 4 in the axial direction, a separate drive 52 is provided for this purpose, which can displace the drive train 25 via a spindle drive 54 (shown only schematically) so that the constriction 7 between the rotor 4 and the stator 2 is widened. If necessary, the constriction 7 can be extended so far that there is a leakage gap S in the region of the sealing line D between the rotor 4 and the stator 2. In this case, a bias between the rotor 4 and stator 2 is usually not completely repealed, since there is a back pressure of the pumped liquid.

Via a signal line 56, the drive 52 is preferably connected to a controller for this purpose. Preferably, the controller is integrated or connected to a controller 58, for example, via the signal line 60. The controller preferably has an input interface through which control or regulation data is input and is adapted to control or regulation in response to that controller or controller Execute control data. For example, a desired volume or a difference between a desired volume and an actual volume can be entered into the controller via this interface. The interface can be a user interface or an interface for connecting a sensor or switch. The controller 58 is used to determine whether and how much the gap geometry changes, so the constriction 7 between the rotor 4 and stator 2 is to be extended. In this embodiment, the controller 58 is initially connected to a sensor 62 which is arranged in the stator 2. The sensor 62 is designed as a temperature sensor and serves to detect the temperature of the stator 2. It should be understood that the sensor 62 may also be arranged to detect the temperature of the rotor 4. For this purpose, the sensor 62 can either detect the outer surface of the rotor 4, or this sensor or an additional can be arranged in the rotor 4. The controller 58 then determines whether a threshold temperature has been reached based on the temperature sensed by the sensor 62 and based on whether and how much the gap geometry is to be changed. This result is sent in the form of an adjustment signal via the line 60 and 56 to the drive 52, so that the drive train 25 is moved to expand the constriction 7 between the rotor 4 and stator 2.

In this exemplary embodiment (FIG. 4), the eccentric screw pump 1 also has a fill level sensor 64, which determines the level of liquid at the inlet 10 of the stator 2. This sensor 64 is also connected to the controller 58. The controller 58 determines based on the received level a shift of the rotor 4 relative to the stator 2 and sends a corresponding signal to the drive 52 for adjusting the drive train 25th

Furthermore, the eccentric screw pump 1 according to this exemplary embodiment (FIG. 4) has a flow sensor 66, which allows a flow of fluid through the Stator 2 measures. Also, this sensor 66 is connected to the controller 58, the controller 58 determines based on the signal of the sensor 66 and the rotational speed of the rotor 4, the flow rate, or the flow volume per revolution. If this is low, this also indicates that a relatively large amount of gas is being delivered, whereby the friction between rotor 4 and stator 2 is increased and at the same time the cooling is reduced. This usually leads to a higher material expansion and in turn to an increased bias between the rotor 4 and stator 2 and as a result to increased wear. An adaptation of the gap geometry is then preferred. Instead of the flow sensor 66 and a pressure sensor 66 may be provided which allows pressure control by means of the adjustment of the constriction between the rotor and stator. With such a pressure sensor, compliance with a minimum pressure or a maximum pressure can be adjusted or controlled by means of adjustment of the constriction. In principle, it should be understood that such a pressure sensor may also be provided in addition to the flow sensor 66. The pressure sensor may also be arranged in the region of the stator or on the inlet side.

It should be understood that embodiments are also preferred in which only one of the three sensors 62, 64, 66 is present. It should also be understood that the controller 58 may also be integrated into the control of the drive 52 and / or the control of the drive motor 36. FIG. 5 shows a further exemplary embodiment, which is basically similar to the exemplary embodiment from FIG. 4. The same and similar elements are in turn provided with the same reference numerals, so that reference is made in full to the above description. It should be understood that the sensors 62, 64, 66 described with reference to Figure 4 may also be employed in the embodiments of Figures 1, 5, 6 and 7, separately or in combination.

According to this embodiment (FIG. 5), in turn, the rotor 4 is arranged to be displaceable relative to the stationary stator 2. However, in this embodiment, the drive motor 36 is also stationary and not displaceable. Overall, the drive shaft 26 is in turn coupled via a universal joint 30 with the output shaft 32 of the drive motor 36. In order to enable a displacement of the rotor 4 and the drive shaft 26, the output shaft 32 is axially displaceably mounted in the output gear 68 of the transmission 34. The gear 68 is coupled to the output shaft 32 with an axially displaceable shaft-hub connection. The gear 34 is thus equipped with a gear 68 designed as a hollow shaft, in which the shaft 32 can be moved. The Output shaft 32 is in turn guided by a seal 70, so that no liquid from the drive inlet housing 14 can penetrate into the transmission 34. A drive 52 (see Fig. 4) can again be arranged on an outwardly lying section 72 of the output shaft 32 in order to enable the axial displacement of the output shaft 32 and in consequence of the rotor 4.

A further, in contrast, modified embodiment is shown in Fig. 6, again the same and similar elements are provided with the same reference numerals, so that reference is made fully to the above description.

Also in the embodiment of FIG. 6, the rotor 4 is displaceable, while the stator 2 is received in a stationary manner in the inlet housing 4 and the outlet housing 20. According to this embodiment, the drive shaft 26 is formed in two parts and has a first part 74 and a second part 76. The two parts 74, 76 are telescopically pushed into each other and between the two parts 74, 76, an expansion member 80 is formed in a recess 78 in the first element 74. The expansion member 80 serves to allow the axial length of the drive shaft 26 by displacement of the second shaft portion 76 to the first shaft portion 74. By the expansion of the expansion member 80 or reduction of the expansion member 80, a displacement of the rotor 4 is made possible.

It is conceivable to form the expansion member 80 as a passive expansion member, in particular as a hydraulic system. A hydraulic serves to maintain a bias between rotor 4 and stator 2 approximately equal so that the biasing force acting on the rotor 4 is substantially constant. When expanding the material of the stator 2 and / or the rotor 4, it is possible that the rotor 4 can move to the left with respect to FIG. 4, compensation by means of the hydraulic in the expansion member 80. This prevents excessive wear as well by an active, controlled by a drive adjustment of the rotor 4 and / or stator 2. The pressure acting in the hydraulic pressure can then be adjusted to the pump pressure.

Finally, FIG. 7 shows an embodiment of the eccentric screw pump 1, which in turn allows a displacement of the rotor 4 relative to the stator 2. In this embodiment, the drive shaft 26 is in turn formed integrally as in the first three embodiments of Figures 1, 4 and 5. The drive shaft 26 is connected by means of a universal joint 30 with the output shaft 32. In the embodiment of FIG. 7, the stub shaft 82, which connects the universal joint 28 to the rotor 4 is formed in two parts and has a first part 84 which is rigidly connected to the rotor 4 and a second part 86 which is connected to the universal joint 28 connected is. The parts 84 and 86 are telescoped into one another and in the part 84 an expansion member 80, corresponding to the expansion member 80 according to FIG. 4, is formed. This expansion element 80 can again be active or passive, passive, for example in the form of a hydraulic system. Alternatively, it can also be provided that acts on the end face 88 of the rotor 4, a drive which moves the rotor 4 axially. 8, an exemplary sequence of a method for operating an eccentric screw pump according to one of the above-described preferred embodiments of an eccentric screw pump according to one of the embodiments 1 to 7 is described. In step 100, the eccentric screw pump 1 is started and the rotor 4 is set in rotation. Step 102 designates the conveyance of liquid from the inlet 10 to the outlet 12 of the stator 2 by rotation of the rotor 4. During this step of the conveying 102, the temperature of the stator 2 is measured by means of a temperature sensor in step 104.

This measured temperature is compared to one or more thresholds in step 106. In step 108, it is then determined whether one or more of the several thresholds has been exceeded, and if no threshold has been exceeded, or already the bias, i. Also, the axial position of the rotor relative to the stator and thus the gap geometry that is the geometry of the constriction 7 with the threshold determined in step 106, made in step 108, the choice to continue to promote liquid and swept back to step 102. Otherwise, in step 1 10, a corresponding bias voltage is set. After resetting the gap geometry if necessary in step S1 10, the process may return to step S102.

For example, it is conceivable that in step 106 the temperature measured in step 104 is determined in relation to a plurality of threshold values, each threshold value representing one equivalent to a relative axial position of rotor 4 and stator 2 relative to one another. In step 1 10, the corresponding axial position provided at the threshold determined in 106 is then adjusted. At the same time, liquid is still being conveyed in step 102. In principle, at the beginning of a delivery process, ie before the rotational movement of the rotor starts relative to the stator, the constriction between rotor and stator is so greatly expanded that due to the internal leakage no or only a low delivery rate occurs. The constriction is then reduced over a limited start-up of about 1, 5 seconds so far that a desired delivery rate or a desired delivery pressure is achieved with it.

Claims

claims

Eccentric screw pump (1) for conveying solids laden liquids, with

a helically wound rotor (4),

a stator (2) having an inlet (10) and an outlet (12) in which the rotor (4) is rotatable about a longitudinal axis (L-ι) of the stator (2), and the one with the rotor ( 4) has corresponding helical inner wall (8),

wherein the rotor (4) has a tapering, preferably conical, shape and / or a varying eccentricity (e- ₁ , e ₂ ) tapering towards the outlet (12) or inlet (10), and

being rotor

(4) and stator (2) are arranged and formed in such a way that at least one chamber (5) is formed, which serves to convey the liquid, and the chamber

(5) is separated by a constriction (7), in particular sealing line (D),

characterized by an adjusting device for adjusting an axial relative position of the rotor (4) and stator (2),

wherein the adjusting device (39) is designed to expand the constriction (7) between the rotor (4) and the stator (2).

Eccentric screw pump according to claim 1, wherein the adjusting device (39) is adapted to expand the constriction (7) between the rotor and stator so far that a leakage gap (S) between the rotor (4) and stator (2) is formed.

Eccentric screw pump according to claim 1 or 2, wherein the adjusting device (39) is adapted to perform the expansion of the constriction (7) in dependence on one or more predetermined operating parameters.

Eccentric screw pump according to claim 3, wherein one of the operating parameters is the temperature of the stator (2) and / or the rotor (4).

Eccentric screw pump according to claim 3 or 4, wherein one of the operating parameters is the delivered liquid volume.

6. Eccentric screw pump according to claim 3, 4 or 5, wherein one of the operating parameters is a liquid level at the inlet (10) of the stator (2).

7. Eccentric screw pump according to one of the preceding claims, wherein the stator (2) is mounted axially displaceable and the adjusting device (39) is set to the stator (2) to move axially to at least partially the constriction (7) between the rotor (4) and stator (2) to expand.

8. Eccentric screw pump according to one of the preceding claims, wherein the rotor (4) is mounted axially displaceable and the adjusting device (39) is adapted to move the rotor (4) axially to at least partially the constriction (7) between the rotor (4) and stator (2) to expand.

9. Eccentric screw pump according to claim 8, wherein a drive train (25) comprising a drive motor (36) and a drive shaft (26) of the rotor (4) is displaceable together with the rotor (4).

10. Eccentric screw pump according to claim 8, wherein the rotor (4) together with the drive shaft (26) relative to a drive motor (36) is displaceable.

1 1. Eccentric screw pump according to claim 10, wherein between the drive shaft (26) and the drive motor (36), a transmission (34) is arranged and the transmission (34) allows axial displacement of the drive shaft (26).

12. Eccentric screw pump according to claim 10, wherein the drive shaft (26) at least two parts and an expansion member (80) which allows an extension and shortening of the drive shaft (26) for axially displacing the rotor (4).

13. Eccentric screw pump according to one of the preceding claims, wherein the longitudinal axis (L-ι) of the stator during operation substantially vertically aligned and the outlet (12) of the stator (2) is above.

14. Eccentric screw pump according to one of the preceding claims, wherein the stator (2) at least in the region of the inner wall (8) of a resilient material, in particular an elastomer, is formed.

15. Eccentric screw pump according to one of the preceding claims,

Adjustment device is formed,

- To expand the constriction between the rotor and stator before the start of a start-up operation or during or after a run-out operation of a drive motor for rotating the rotor, and

- To reduce the constriction between the rotor and stator before starting during the startup of the drive motor.

16. Eccentric screw pump according to one of the preceding claims, wherein the adjusting device has an input interface for receiving a pressure signal and is designed to expand or reduce the constriction between the rotor and stator in response to the pressure signal.

17. Eccentric screw pump according to one of the preceding claims, wherein the adjusting device has an input interface for receiving a volume quantity signal and is designed to expand the constriction between the rotor and stator in dependence of the volume quantity signal such that at a value of the volume signal, which signals that a Since the beginning of a delivery process volume delivered corresponds to a desired volume, the constriction between the rotor and stator is extended such that no further promotion of a volume from the outlet of the stator takes place more.

18. Eccentric screw pump according to one of the preceding claims, characterized in that the adjusting device is designed to adjust the axial relative position of the rotor (4) to the stator (2), while the rotor rotates relative to the stator.

19. A method for operating an eccentric screw pump (1) according to at least one of claims 1 to 14, comprising the steps:

Driving the rotor (4) to convey a liquid;

Expanding the constriction (7) between the rotor (4) and stator (2) by relative axial displacement of the rotor (4) and stator (2) to each other.

The method of claim 19, wherein the step of expanding the restriction (7) comprises: Setting a leakage gap (S) between rotor (4) and stator (2).

The method of claim 19 or 20, further comprising:

Measuring a temperature of the rotor (4) and / or the stator (2); depending on the measured temperature, relative axial displacement of rotor (4) and stator (2).

The method of any one of claims 19 to 21, further comprising:

Determining a liquid level at the inlet (10) of the stator (2);

depending on the specific fluid level, relative axial displacement of rotor (4) and stator (2).

The method of any one of claims 19 to 22, further comprising:

Determining a delivered volume of fluid per revolution of the rotor (4);

depending on the determined volume of liquid, relative axial displacement of rotor (4) and stator (2). 24. The method according to any one of claims 19 to 23,

characterized in that

The constriction between rotor and stator at the beginning of a start of a

Drive motor is extended to rotate the rotor, and

The constriction between the rotor and stator is reduced after the beginning of a startup of the drive motor.

Method according to one of claims 19 to 24,

characterized in that

a pressure is detected by means of a pressure sensor, and

The constriction between the rotor and the stator increases or decreases as a function of the pressure.

Method according to one of claims 19 to 25,

characterized in that

a set volume amount is detected, and

The constriction between rotor and stator depending on the Sollvolu amount increased or decreased. Method according to one of claims 19 to 26,

characterized in that the rotor is displaced relative to the stator in the axial direction along the axis of rotation, while the rotor is driven for conveying the liquid relative to the stator in a rotational movement about the axis of rotation.