ECCENTRIC SCREW PUMP

Abstract

The invention relates to a progressive cavity pump, comprising at least: a stator (1); a rotor (2), which rotates in the stator (1); a drive (3); a pump housing (4), which is connected to the stator (1) and has at least one inlet opening or outlet opening for the medium to be conveyed; a connecting shaft (9), which is driven by the drive and rotates centrally about an axis (R) in ideal operation of the pump; a coupling rod (10), which is arranged, for example, in the pump housing (4), is articulated at the drive-side end to the connecting shaft (9) and is articulated at the rotor-side end to the rotor (2), and produces an eccentric motion of the rotor end (7) when the connecting shaft (9) rotates centrally. Said pump is characterized in that at least one sensor (15, 16) is arranged in the region of the connecting shaft (9) in order to detect or measure a deviation from true running, which sensor determines a motion profile of the connecting shaft (9) at a specified angular position of the connecting shaft by virtue of the fact that the distance of the surface of the connecting shaft (9) from the sensor (15, 16) is measured.

Claims

1. An eccentric screw pump comprising: a stator, a rotor rotating in the stator, a drive, a pump housing connected to the stator and having at least one inlet or outlet opening for a medium to be conveyed, a connecting shaft driven by the drive and rotating concentrically with an axis on ideal operation of the pump, a coupling rod for example in the pump housing and connected to the connecting shaft at a drive-side end and to the rotor at a rotor-side end thereof and generating eccentric movement of the rotor-side end on concentric rotation of the connecting shaft fir, and at least one sensor mounted adjacent the connecting shaft for detecting or measuring deviation from axially concentric rotation thereof for determining a movement profile at a predetermined angular position of the connecting shaft by measuring a distance between an outer surface of the connecting shaft and the sensor.

2. The eccentric screw pump according to claim 1, wherein at least two of the sensors adjacent the connecting shaft measure concentricity deviation thereof, are in different angular positions offset relative to one another by an angular offset, and each determine a movement profile of the connecting shaft by detecting a distance of the surface of the connecting shaft from the respective sensor at different angular positions.

3. The eccentric screw pump according to claim 2, wherein the angular offset is at least 10°.

4. The eccentric screw pump according to claim 1, wherein the sensor is a contactless inductive or optical proximity sensor.

5. The eccentric screw pump according to claim 1, wherein the sensor is or are provided axially of the pump between the drive-side end of the connecting shaft and a coupling-side shaft seal that seals the pump housing in a liquid-tight manner with respect to the surroundings or with respect to a connection housing connected to the pump housing.

6. The eccentric screw pump according to claim 1, further comprising a connecting housing between the pump housing and the drive, provided at least in regions in the connecting housing, the sensor being provided on or fastened in or on the connection housing.

7. The eccentric screw pump according to claim 6, wherein the connecting housing is a lantern or a support block.

8. A method of operating an eccentric screw pump according to claim 1, wherein the sensor determines the movement profile of the connecting shaft in at least one predetermined angular position of the connecting shaft by measuring a distance of the surface of the connecting shaft from the sensor.

9. The method according to claim 8, wherein with two sensors provided in different angular positions, each determines a movement profile of the connecting shaft for a respective different angular position by measuring the respective distance between the surface of the connecting shaft and the respective sensor.

10. The method according to claim 8, wherein the movement profile is determined or measured continuously.

11. The method according to claim 8, wherein the movement profile or the values measured with the sensor or with the sensors are compared with stored reference profiles or reference values, and an error message is generated and/or displayed and/or transmitted when a predetermined deviation is exceeded.

12. An eccentric screw pump comprising: a stator; a rotor rotating in the stator; a drive; a pump housing connected to the stator and having at least one inlet or outlet opening for a medium to be conveyed; a connecting shaft driven by the drive and rotating concentrically with an axis on ideal operation of the pump; a coupling rod in the pump housing and having a drive end connected to the connecting shaft and an axially opposite rotor end connected to the rotor, the coupling rod generating eccentric movement of the rotor end on axially concentric rotation of the connecting shaft; and a sensor axially and radially fixed adjacent the connecting shaft for detecting or measuring radial deviation from axially concentric rotation thereof for determining a movement profile at a predetermined angular position relative to the axis of the connecting shaft by measuring a distance between an outer surface of the connecting shaft and the sensor.

Description

[0027] The invention is explained in more detail below on the basis of drawings that are merely exemplary embodiments. They show

[0028] FIG. 1 shows an eccentric screw pump in a simplified side view,

[0029] FIG. 2 shows an enlarged detail of the subject matter according to FIG. 1,

[0030] FIG. 3 shows a modified embodiment of an eccentric screw pump in a simplified side view and

[0031] FIG. 4 shows a detail from the subject matter according to FIG. 3 in a perspective view.

[0032] The figures each show an eccentric screw pump that, in its basic design, has a stator 1, a rotor 2 rotating in the stator 1, and a drive 3 for the rotor 2. A pump housing 4, which is also referred to as a suction housing 4, is connected to the stator 1 (e.g. on the suction side). A housing part that is connected to the stator 1 at the opposite end of the stator 1 (e.g. on the pressure side), is referred to as a connecting piece or pressure connection piece 5. The pump housing 4 has an inlet opening 6 (or, depending on the pumping direction, outlet opening), via which, for example, of the medium to be conveyed is supplied that is dependent on the pump housing 4 via the stator/rotor 1, 2 to the pressure connection piece 5. The drive 3 is equipped with an output shaft (not shown) that is connected to a connecting shaft 9. This connecting shaft 9 is a plug-in shaft 9 in this embodiment. In this embodiment, the rotor 2 is connected to the connecting shaft 9 via a rigid coupling rod 10, and the coupling rod 10 is connected to the connecting shaft 9 via a drive-side joint 11 and to the rotor 2 via a rotor-side joint 12, such that eccentric movement of the rotor 2 or rotor end 7 is made possible via the coupling rod 10 and the joints 11, 12. The drive thus operates on the connecting shaft 9 that rotates centrally about an axis R under ideal conditions. The eccentric movement of the rotor end 7 is made possible by the coupling rod 10. In principle, however, it is also possible to work with embodiments without joints, in that for example the coupling rod is of elastic design. Such an embodiment is not shown. The (elastic) coupling rod can also be formed in one piece with the rotor and consequently form one end of the rotor. Moreover, embodiments in which the coupling rod is provided with one or more conveying devices, for example with a worm that can be a hollow screw or a solid screw, are also basically detected. Such coupling rods that carry a worm, are for example in the case of eccentric screw pumps in when serving as funnel pumps. Such an embodiment is also not shown in the drawing. However, the explanations in the description of the figures relate equally to the mentioned embodiments (not shown).

[0033] A connecting housing 14 is provided between the pump housing 4 and the drive 3. In the embodiment according to FIGS. 1 and 2, this connecting housing 14 is a so-called cradle. The connecting shaft 9 is arranged at least partially inside this connection housing 14. For the liquid-tight separation of the pump housing 4 from the environment or against the drive 3, the connecting shaft 9 is sealed with a shaft seal 13 that can be for example a sliding ring seal.

[0034] According to the invention, at least one sensor 15, 16 is spacedly adjacent the connecting shaft 9 for detecting or measuring a concentricity deviation, this sensor determining a movement profile of the connecting shaft 9 in a predetermined angular position of the connecting shaft 9 by measuring the distance of the surface of the (cylindrical) connecting shaft 9 from the sensor 15, 16. In this illustrated embodiment, two sensors 15, 16 are provided that are arranged in different angular positions offset relative to one another by an angular offset. In this embodiment, the angular offset is approximately 90°. The sensors 15, 16 are designed for example as contactless inductive proximity sensors.

[0035] Under ideal conditions, the connecting shaft 9, driven by the drive 3, rotates concentrically to the axis of rotation R since it has a circular cross-section, so the distance of the surface from the fixedly positioned sensor 15, 16 does not change during rotation, and measurement of the distance as a function of time and consequently from the angular position of the shaft 9 leads to a constant signal. In practice, however, a concentricity deviation occurs, specifically as a function of the state of wear of various parts of the pump. A concentricity deviation results in the sensor 15, 16 measuring a different distance during operation for different angular positions of the connecting shaft. With the aid of the sensor 15 or 16 or with the aid of the sensors 15, 16, a concentricity deviation can consequently be determined very easily and reliably and from this concentricity deviation it is possible to infer a wear state. For this purpose, it is possible for example to compare the determined values with stored reference values, such that an error message is generated and/or displayed and/or transmitted when a predetermined deviation is exceeded. An optical display (not shown) can for example be provided on the pump. Alternatively or additionally, acoustic signals can also be generated. It is also possible to transmit the signal to a pump controller so it can be displayed at the controller. The sensors and/or the evaluation of the signals can also be fed to a pump control (e.g. to a PLC controller).

[0036] While FIG. 1 shows an embodiment of an eccentric screw pump in which the connecting housing 14 is a so-called cradle, FIG. 2 shows a modified embodiment of an eccentric screw pump in which the connecting housing 14 is a support block. In particular in FIG. 4 the two sensors 15, 16 offset by 90° can be seen adjacent the bearing block 14 that determine or monitor a concentricity deviation of the connecting shaft 9 (not shown) (plug-in shaft). Detachable covers, e.g. cover plates 8, on which for example a sensor 16 can be fastened, can be seen on the housing 14. The sensor 15 is fixed to a stationary part of the housing 14. The drive 3 is not explicitly illustrated in the embodiment according to FIGS. 3 and 4. It can be connected to the drive shaft 17.