ECCENTRIC SCREW PUMP

Abstract

The invention relates to an eccentric screw pump comprising at least one stator (1) made from an elastic material and a rotor (2) that is rotatable in the stator (1), wherein at least some regions of the stator (1) are surrounded by a stator casing (3), and the stator casing (3), as a casing split along its length, consists of at least two casing segments (19) and forms a stator clamping device by means of which the stator can be clamped against the rotor (2) in the radial direction, wherein the stator clamping device has one or more movable adjusting elements which work on the casing segments (19) to adjust and clamp the stator. Said pump is characterised in that the stator clamping device comprises one or more actuators which are connected to the adjusting elements or are equipped with adjusting elements for an automated advancement of the stator.

Claims

1. An eccentric screw pump comprising: at least one stator of elastic material and extending along an axis; a rotor rotatable about the axis in the stator; an axially split stator housing at least partially surrounding the stator and, formed by at least two housing segments; and a stator-clamping device that can press the housing segments radially against the stator and thereby press the stator against the rotor and that has one or more movable adjusting elements that bear radially inward on the housing segments for radially adjusting and clamping the stator, and one or more actuators connected or provided with the adjusting elements for automatic positioning of the stator segments.

2. The eccentric screw pump according to claim 1, further comprising: a controller connected to the actuators for operating the actuators as a function of status data or operating parameters of the eccentric screw pump.

3. The eccentric screw pump according to claim 2, wherein the controller is connected with a pump drive or a pump drive controller, or integrated thereinto, and that the actuators can be driven by the controller as a function of the drive power consumed or the motor current or other operating parameters of the pump.

4. The eccentric screw pump according to claim 2, wherein the adjusting elements can be driven by the controller as a function of one or more measurement values that are recorded by one or more sensors connected with the controller.

5. The eccentric screw pump according to claim 4, wherein the sensors are temperature sensors, pressure sensors or through-flow sensors.

6. The eccentric screw pump according to claim 1, wherein the actuators are electrical or electric motor drives, hydraulic drives, or pneumatic drives.

7. The eccentric screw pump according to claim 1, wherein the adjusting elements are adjusting screws, pins, or rods that can be actuated by the actuators.

8. The eccentric screw pump according to claim 7, wherein the adjusting screws or adjusting pins and the actuators act on the housing segments radially.

9. The eccentric screw pump according to claim 7, wherein the stator-clamping device includes an axially displaceable cam ring bearing radially on wedge-like cam faces of the housing segments and the adjusting screws or adjusting pins and the actuators bear axially on this axially displaceable clamping ring.

10. The eccentric screw pump according to claim 1, wherein the adjusting elements include clamping levers and axially displaceable clamping rings engaging the housing segments and operated by the clamping levers.

11. The eccentric screw pump according to claim 1, wherein the adjusting elements include: at least one threaded adjusting ring rotatable about the axis, an axially displaceable adjusting ring threaded on the rotatable ring and engaging the housing segments such that on rotation of the threaded ring the axially displaceable ring cams the housing segments radially inward or outward.

Description

[0017] In the following, the invention will be explained in greater detail with reference to a drawing that shows a single embodiment. In the drawing:

[0018] FIG. 1 is a section through an eccentric screw pump according to the invention in a first embodiment,

[0019] FIG. 2 shows a detail of the pump of FIG. 1 with drives,

[0020] FIG. 3 shows a modified embodiment of the structure shown in FIG. 2,

[0021] FIGS. 4, 5, and 6 are simplified views of the pump of FIG. 1 in modified embodiments,

[0022] FIG. 7 is a detail from a modified embodiment of the pump of FIG. 1,

[0023] FIG. 8 is another detail from a further embodiment of the pump of FIG. 1,

[0024] FIG. 9 shows a further modification of the invention,

[0025] FIG. 10 shows an alternative embodiment with radial adjusting elements, and

[0026] FIG. 11 shows a modified embodiment of an eccentric screw pump with integrated activation cushions.

[0027] In the figures, an eccentric screw pump is shown that basically comprises a stator 1 of an elastic material and a rotor 2 mounted in the stator 1, the stator 1 being at least partially surrounded by a stator housing 3. Furthermore, the pump has an intake fitting 4 as well as an output fitting 5, also referred to as a pressure connector. An unillustrated pump drive is also provided with and the pump drive acts on the rotor 2 through a coupling rod 6. The coupling rod is connected between the rotor 2 and a drive shaft through couplings 7. The pump is usually mounted on a base plate 8 that can be supplied with the pump or also a base plate 8 of the user. The stator 1 is connected in known manner with a connection flange 9 of the intake fitting at its upstream end and with a connection flange 10 of the output fitting 5 at its downstream end. In this regard, connection does not take place directly to these connection flanges 9 and 10 here shown, but rather with the interposition of respective adapters 11 and 12. These adapters 11 and 12 are also referred to as centering rings or segment holders.

[0028] The stator 1 is an axially split stator and for this purpose here is formed by two half shells 1a and 1b that each extend over an angle of 180°. Axially split means subdivided along a stator axis L or parallel to it. The split plane between the half shells consequently runs parallel to the axis L. This axially split embodiment of the elastomeric stator makes it possible to disassemble and assemble the stator 1 while the intake fitting 4, an output 5, and rotor 2 are mounted in place. In this regard, reference is made to WO 2009/024279 [U.S. Pat. No. 8,439,659].

[0029] In order to guarantee a perfect seal in spite of this split method of construction, the stator 1 and its half shells 1a and 1b have seal faces 13 and 14 on their ends. The half shells 1a and 1b can be set onto stator holders with their end seal faces 13 and 14, and these stator holders are provided on the adapters 11, 12 in the embodiment shown here. The adapters 11 and 12 can be set into known holders of the intake fitting 4 and an output fitting 5 so that the intake fitting 4 and the output fitting 5 can be of conventional construction. The end seal faces 13 and 14 of the stator are be frustoconical or as frustoconical housing segments, specifically in the “inner cone” embodiment. The stator holders also have complementary frustoconical seal counter faces 17 and 18 that here are outer cones. Sealing takes place via rubber squeezing. Fixation and sealing of the half shells 1a and 1b takes place using the stator housing 3. It is an axially split housing and for this purpose has multiple housing segments 19, here four. This stator housing 3 with its housing segments 19 forms a stator-clamping or -adjustment apparatus with which the axially split stator 1 can be both fixed in place and sealed and a desired prestress or bias can be set in the stator 1.

[0030] For this purpose, the housing segments 19 have clamping flanges 20 on their ends that have first clamping surfaces 21 that are here wedges. Clamping elements 22 set onto the clamping flanges 20 are here clamping rings and provided with second clamping surfaces 24 that are also wedges. The first clamping surfaces 21 and the second clamping surfaces 24 are now configured in such a manner and interact in such a manner that the stator housing 3, 19 is radially clamped against the stator 1 on axial displacement of the clamping elements or clamping rings 22. The clamping ring 22 shown here can also be replaced with individual clamping segments, so that the individual clamping segments then form an interrupted clamping ring, so to speak. Such an embodiment is not shown in the figures, but the explanations in the figure description apply analogously.

[0031] Here according to FIG. 1, the clamping element is provided as a annularly continuous clamping ring 22 that has a annular second clamping surface 24 (on the inside), and this second clamping surface interacts with the first clamping surfaces 21 of the housing segments 19. In FIG. 1, it can be seen that during movement of the clamping ring 22 in axial direction a, a clamping force that acts in a radial direction R is generated due to the interacting wedge surfaces 21 and 24. To displace the clamping rings 22 in the direction a, adjusting elements are provided that can be adjusting screws or pins 25, for example.

[0032] According to the invention, one or more actuators 40 are provided that are connected with these adjusting elements for automatic positioning the stator 1 or are equipped with them. Proceeding from FIG. 1, this is shown schematically in FIG. 2.

[0033] There, stepper motors are shown as actuators 40 that act on the clamping ring 22 parallel to the axis through adjusting elements 25. The adjusting screws shown in FIG. 1 are consequently replaced by the linearly displaceable adjusting elements 25 in this embodiment. In this regard, it is practical to provide at least two, preferably at least three adjusting elements 25 for each clamping ring 22, and in this regard, also three respective actuators 40, so that a total of six adjusting elements are provided for the pump. The possibilities can be further optimized if four adjusting elements 25 are provided at each pump end and consequently a total of eight adjusting elements 25 are provided. In practice, a compromise will take place in this regard, between increasing the number of adjusting elements to improve positioning and the related control effort. In this regard, it is evident that the drive motors 40 are each attached to one housing part, for example to the connection adapters 11, 12. In this regard, an embodiment is shown in FIG. 2, in which the drive motors 40 move axially on illustrated rails. Forces are absorbed by these rails. Alternatively, however, the possibility also exists of fixing the motor itself, for example when using gear racks.

[0034] An alternative embodiment is shown in FIG. 3, in which the drives 40 are configured not as stepper motors, but rather as cylinders, for example hydraulic cylinders or pneumatic cylinders. In this regard, adjusting elements 25′ are formed by the pistons of these cylinders. The pistons of the cylinders 40 consequently press parallel to the axis on the respective clamping ring 22.

[0035] While the two clamping rings 22 on the two pump ends can be actuated separately and independently of one another according to FIGS. 1 to 3, FIG. 4 shows an embodiment in which the two clamping rings 22 are clamped against one another by one or more drives 40. Thus, FIG. 4 shows an embodiment in which the two clamping rings 22 can be displaced by a lever linkage. For this purpose, at least one push/pull connector rod or connection rod 29′ is connected with each clamping ring 22, and the two connection rods 29′ are connected with one another via a common clamping lever 29. In FIG. 4, only one such lever arrangement is shown in this regard. An identical lever arrangement is provided on the opposite unillustrated side. The clamping or activation lever 29 can be tilted by the drive 40, and thereby the two clamping rings 22 can be pressed together. In FIG. 4, the drive is merely shown schematically. Because a clamping lever 29 is preferably provided on each end of the pump the possibility exists of providing a separate drive for each clamping lever 29. Preferably, however, the two clamping levers 29 will be coupled with one another and acted on by a common drive.

[0036] Here according to FIG. 5, clamping levers 29 are also connected with the clamping rings 22, and here, however, each clamping lever 29 itself can be actuated by a respective drive 40. The two drives 40 shown can be cylinders (hydraulic cylinders, for example) or threaded spindles that can be attached by a coupling below the base plate 8, for example. In this embodiment, consequently each clamping ring can be displaced and thereby operated separately by the respective drives 40. In a modified embodiment, however, the possibility also exists in the arrangement according to FIG. 5 to connect the two clamping levers 29 with one another with the interposition of a common drive, and to clamp the two clamping rings 22 against one another in this manner. Furthermore, in FIG. 5, as well, only the arrangement for the visible side of the pump is shown. On the unillustrated opposite side, another such arrangement with clamping levers 29 can be provided. These can then be separately actuate using respective drives, or, alternatively, common drives can also be used.

[0037] According to FIG. 6, the two clamping rings 22 can be adjusted by linear motors 40 that are each connected with the clamping rings 22 through respective adjusting elements 25. However, the linear motors 40 shown there can also be replaced with other actuators, for example cylinders. The arrangement that can be seen in the figure, with adjusting elements 25 and motors 40, is also provided on the unillustrated opposite side.

[0038] FIG. 7 shows a modified embodiment in which a rotatable adjusting ring 32 is provided as an adjusting element. This ring is mounted so as to rotate and is axially displaced on such rotation. For this purpose, the adjusting ring is mounted on the respective housing part or connection adapter 11, 12 by a screwthread 30. On rotation of the adjusting ring 32, the ring moves on the housing part or the adapter 11, 12 axially, because of the screwthread 30, so that in this way, the clamping ring 22 is thereby displaced with the wedge surfaces, and the housing segments are clamped. Here according to FIG. 7, only the adjusting ring consequently rotates, and the clamping ring 22 is only moved axially. The adjusting ring 32 can consequently rotate not only relative to the housing, but also relative to the clamping ring 22. To actuate the rotatable adjusting ring 32, the ring has gear teeth 31 on its outer periphery, so that an unillustrated drive can act on the adjusting ring 32 on its outer periphery through a drive pinion. Automated positioning according to the invention also is effective in this way.

[0039] A comparable concept is implemented here according to FIG. 8. There, a separate, rotatable adjusting ring 32 is also provided as an adjusting element. On rotation of the adjusting ring 32, the clamping or cone ring 22 with the unillustrated wedge surfaces 24 is displaced axially. For this purpose, the adjusting ring 32 has one or more angled surfaces 33 on its side facing the clamping ring 22. The clamping ring 22 has complementary angled faces 34 in the form of slanted surfaces on its surface facing the adjusting ring 32. These angled faces 33 and 34 interact in such a manner that on rotation of the adjusting ring 32, the clamping ring 22 is displaced axially. In contrast to the embodiment according to FIG. 7, here only the clamping ring 22 moves only axially, while the adjusting ring 32 only rotates. In this embodiment, as well, the possibility exists of providing the adjusting ring 32 with outside gear teeth so that a drive can mesh with it. Alternatively here according to FIGS. 7 and 8, however, linear adjusting elements can also act on the adjusting ring tangentially. This is not shown. Furthermore, the clamping ring 22 is not shown in section in FIG. 8 (also not in FIGS. 4, 5, and 6), so that the clamping surfaces 24 provided on the clamping ring 22 cannot be seen in these figures.

[0040] The concept shown in FIGS. 7 and 8 with a rotatable adjusting ring can be varied according to FIG. 9. There, the rotatable adjusting ring 32 has multiple recesses 35 that are guide tracks and in which is held a body or sliding body, for example a ball 36. These balls 36 bear axially against the clamping ring 22. The guide tracks are pocket-like guide grooves 35 whose depth decreases angularly from one end of the groove to the other end of the groove, in the direction of the arrow P, so that the rolling bodies, for example balls, lie on the rising groove floor on rotation. Alternatively, other rolling bodies, for example cylinders, or basically also sliding bodies can be used. Furthermore, in FIG. 9 only the adjusting ring 32 with the guide grooves 35 is shown. The possibility exists that the clamping ring is also equipped with complementary opposite guide tracks on the surface facing the adjusting ring, so that the balls 36 are then guided both in the guide tracks 35 of the adjusting ring and in the unillustrated complementary guide tracks of the clamping ring.

[0041] A modified embodiment is shown in FIG. 10. This pump corresponds to the pump known from WO 2009/024279 [U.S. Pat. No. 8,429,659], with radially oriented adjusting screws or adjusting elements 25. In turn, actuators 40 can act on these adjusting elements 25. This is merely shown in FIG. 10.

[0042] The drives 40, which are shown schematically in the figures, are critical to the invention, since they actually allow automated positioning of the clamping elements, for example the clamping rings. These drives are preferably equipped with controllers and connected with controllers that drive the drives as a function of status data or operating parameters of the eccentric screw pump. However, sensors can also be provided that provide such status data. No details are shown in the figures.

[0043] An alternative embodiment is shown in FIG. 11. In this embodiment, clampable housing segments are completely eliminated. Consequently, the stator-clamping device is not provided with housing segments, but rather by intermediate elements between the stator housing 3 and the stator 1. Here, these intermediate elements are cushions that change in volume, for example hydraulic cushions 41 that are provided between the stator housing 3 and the stator 1. This embodiment is also practical in the case of an axially split stator. It is also possible to work with an axially split stator housing 3 or housing segments 19. However, this embodiment can also be implemented with a one-piece stator housing. The hydraulic cushions 41 can also be controlled automatically and remotely, so that with such an embodiment, as well, adaptation of the geometry to specific operating parameters is possible.