ECCENTRIC SCREW PUMP

Abstract

The invention relates to an eccentric screw pump, comprising at least one stator (1) composed of an elastic material and a rotor (2) that can be rotated in the stator (1), the stator (1) being surrounded by a stator casing (3) at least in some regions. The stator casing (3) consists of at least two casing segments (19) as a longitudinally divided casing and forms a stator clamping device, by means of which the stator (2) can be clamped against the rotor (1) in the radial direction. The pump is characterized in that the casing segments (19) have at least one clamping flange (20) having first clamping surfaces (21) at each end of the casing segments and that one or more clamping elements (22, 23), which can be displaced in the axial direction and have second clamping surfaces (24), are placed onto the clamping flange (20), the first clamping surfaces (21) and the second clamping surfaces (24) being designed in such a way and interacting in such a way that the stator casing (3) can be clamped against the stator in the radial direction in the course of an axial displacement of the clamping elements (22, 23).

Claims

1. An eccentric screw pump comprising: an axially split stator made of an elastic material and extending along an axis; a rotor rotatable in the stator at least generally about the axis, the stator surrounding the stator at least in some regions and formed by at least two casing segments that are clampable radially against the rotor, each casing segment having opposite ends each in turn having at least one clamping flange with a first clamping surface; and respective clamping elements with second clamping surfaces displaceable axially against the second clamping surfaces so as to press the stator casing against the stator on axial displacement of the clamping elements.

2. The eccentric screw pump defined in claim 1, wherein the stator segments are stator subshells.

3. The eccentric screw pump defined in claim 1, wherein the first clamping surfaces or the second clamping surfaces are wedges.

4. The eccentric screw pump defined in claim 1, wherein the clamping elements are clamping rings engaging the first clamping surfaces of the casing segments.

5. The eccentric screw pump defined in claim 1, wherein the clamping elements are each formed by an annular array of clamping segments that coact with the first clamping surfaces of the casing segments.

6. The eccentric screw pump defined in claim 1, further comprising: actuators for displacing the clamping elements axially against the respective flanges.

7. The eccentric screw pump defined in claim 6, wherein the actuators are set screws, adjusting rods, clamping rods or clamping levers (that act on the clamping elements.

8. The eccentric screw pump defined in claim 4, wherein the clamping rings each have a multipart configuration and consist of an outer ring and an inner ring, the actuators bearing on the outer ring, the second clamping surfaces being on the inner ring.

9. The eccentric screw pump defined in claim 1, further comprising: a clamping subassembly that has a double wedge ring having the second clamping surfaces and enclosing the casing segments and two clamping rings that can be pressed against one another and have the first clamping surfaces .

10. The eccentric screw pump defined in claim 9, wherein each of the clamping rings is rotatable and moves axially on rotation.

11. The eccentric screw pump defined in claim 6, wherein the actuator is a rotatable adjusting ring or a rotatable adjusting ring assembly that axially displaces the clamping elements on. rotation.

12. The eccentric screw pump defined in claim 1, wherein locking recesses or projections, are provided on the casing segments or clamping flanges that prevent rotation or axial movement of the casing segments by coacting with projections or recesses, on a housing part of the a pump or on separate adapters.

Description

[0019] The invention is described in further detail below with reference to a schematic drawing showing a single embodiment.

[0020] FIG. 1 is a section through a first embodiment of an eccentric screw pump according to the invention;

[0021] FIG. 2 shows a second embodiment of the pump of FIG. 1;

[0022] FIG. 3 shows a third embodiment of the invention;

[0023] FIG. 4a is a perspective view of a fourth embodiment of the invention;

[0024] FIG. 4b is an enlarged section through the pump of FIG. 4a;

[0025] FIG. 4c is another enlarged view of the pump of FIG. 4a;

[0026] FIG. 4d shows a modified version of the pump of FIG. 4c;

[0027] FIG. 5 is a section through a fifth embodiment of the invention;

[0028] FIG. 6 shows a sixth embodiment of the pump of FIG. 1;

[0029] FIG. 7 shows a modified seventh embodiment of the invention;

[0030] FIG. 8 shows an eighth embodiment of the invention;

[0031] FIG. 9 shows a ninth embodiment of the invention; and

[0032] FIG. 10 shows a tenth embodiment of the invention.

[0033] The figures show an eccentric screw pump that, in its basic construction, has a stator 1 made of an elastic material and a rotor 2 supported in the stator 1 that is surrounded at least in some regions by a stator casing 3. Furthermore, the pump has a intake housing 4 as well as a connector 5 that is also referred to as a pump output nozzle. An unillustrated drive is also provided and is connected by a coupling rod 6 on the rotor 2. The coupling rod is connected via coupling joints 7 to the rotor 2 at one end the one hand and to a shaft of the drive at the opposite end. The pump is usually mounted on a base plate 8 that is either delivered with the pump or also a base plate 8 or that is otherwise present. The stator 1 is connected in an inherently known manner at one end to a connecting flange 9 of the intake housing 4 and at its other end to a connecting flange 10 of the connector 5. In the illustrated embodiment, the connection is not made directly to these connecting flanges 9, 10, but rather through interposition a respective adapters 11 and 12. These adapters 11, 12 are also referred to as centering rings or segment holders.

[0034] The stator 1 is formed as an axially split stator and consists of two stator subshells 1a, 1b that form in the illustrated embodiment half-shells that each cover an angle of 180°. “Axially split” means divided along the stator longitudinal axis L or parallel thereto. The separating plane between the subshells therefore runs along or parallel to the longitudinal axis L. This axially split configuration of the elastomeric stator makes it possible to disassemble and reassemble the stator 1 while the intake housing 4, pump output nozzle 5, and rotor 2 are mounted. Reference is made in this regard to WO 2009/024279.

[0035] In order to ensure the proper tightness of the stator despite this split construction, the stator 1 or its stator subshells 1a, 1b have sealing end faces 13, 14. The stator subshells 1a, 1b can be mounted with their sealing end faces 13, 14 on stator holders that are provided on the adapters 11, 12 in the embodiment illustrated here. The adapters 11, 12 themselves can be inserted into inherently known holders of the intake housing 4 and pump output nozzle 5, so that the intake housing 4 on the one hand and the pump output nozzle 5 on the other hand can be formed in a conventional configuration. The sealing end faces 13, 14 of the stator 1 are frustoconical or formed as frustoconical surfaces, and they are particularly provided with “inner frustoconical surfaces” in the illustrated embodiment. The stator holders also have corresponding frustoconical sealing counter-surfaces 17, 18 that can have outer frustoconical surfaces in the illustrated embodiment. The seal is achieved through rubber compression. The fixing and sealing of the stator subshells 1a, 1b is done with the aid of the stator casing 3. This is formed as an axially split casing and has several casing segments 19 for this purpose—four in the illustrated embodiment. This stator casing 3 forms with its casing segments 19 a stator clamp or stator adjusting device with which the axially split stator 1 can be fixed and sealed on the one hand and a desired tension or pretension can be applied to the stator 1 on the other hand.

[0036] To this end, the casing segments 19 have clamping flanges 20 at their ends with first clamping surfaces 21 that are formed as wedges 21 in the illustrated embodiment. Clamping elements 22, 23 are placed on the clamping flanges 20 and provided with second clamping surfaces 24 that are also formed as wedges 24. The first clamping surfaces 21 and the second clamping surfaces 24 are formed and coact such that the stator casing 3, 19 is biased radially against the stator 1 by axial displacement of the clamping elements 22, 23.

[0037] FIG. 1 shows a first embodiment in which a completely annular clamping ring 22 is provided as a clamping element that (internally) has an annular second clamping surface 24 that coacts with the first clamping surfaces 21 of the casing segments 19. FIG. 1 shows that, on movement of the clamping ring 22 in the axial direction a, a clamping force is produced by to the coacting wedges 21 and 24 that acts in radial direction R. For the purpose of displacing the clamping ring 22 in the direction a, actuating elements 25 are provided that are formed as set screws 25 in the illustrated embodiment according to FIG. 1. In the illustrated embodiment, these actuating elements or set screws 25 are held on the adapters 11, 12. In embodiments without adapters, they would be held in an appropriate manner on the housing parts, namely the intake housing 4 and the connector 5. Moreover, it can be seen in FIG. 1 that the clamping ring 22 in the illustrated embodiment illustrated therein has a multipart configuration and consists of an outer ring 22a and an inner ring 22b, with the set screws 25 pressing on the outer ring 22a and the wedges 24 on the frustoconical inner ring 22b.

[0038] The construction and functionality of the second embodiment according to FIG. 2 correspond to those of the embodiment according to FIG. 1, except that the set screws 25 according to FIG. 1 are formed as pressure screws and those according to FIG. 2 are formed as lag screws.

[0039] In the embodiment according to FIG. 3, adjusting rods or clamping rods 25 are provided as actuating elements with which the two clamping rings 22 are pressed against one another. While FIGS. 1 to 3 show embodiments with annular clamping ring 22, a modified fourth embodiment is illustrated in FIGS. 4A and 4B in which several individual clamping segments 23 are provided as actuating elements, each of which has second clamping surfaces 24, with these second clamping surfaces 24 coacting with the first clamping surfaces 21 of the casing segments 19. A comparison of FIGS. 4A to 4D shows that a clamping segment 23 is associated with each casing segment 19 at each of its ends. The clamping segments 23 are received in suitable recesses or holders 26 in the adapters 11, 12. Set screws 25 are provided as actuating elements that are held on the adapters 11, 12 and act on the clamping segments 23. This embodiment also functions according to the wedge principle according to the invention.

[0040] FIG. 5 shows another embodiment in which the clamp has a separate clamping subassembly 27 at each stator end. This separate clamping subassembly 27 has several double wedge segments 28 as well as two clamping rings 22 that can be pressed together. The double wedge segments 28 have exterior first wedges 21, and both clamping rings 22 have interior second wedges 24. The two clamping rings 22 are pressed against one another through interposition of the double wedge segments 28, so that, on clamping and consequently the displacement of the two clamping rings 22′, the wedge segments 28 are displaced radially and thus act on the stator casing 3 radially. In the illustrated embodiment, a double wedge segment 28 is associated with each casing segment 19 at the respective end.

[0041] FIG. 6 shows a modified embodiment that corresponds in its basic configuration to the embodiments according to FIGS. 1 and 2. While the set screws 25 extend axially in FIGS. 1 and 2, FIG. 6 shows an embodiment in which the set screws 25 extend obliquely, specifically substantially parallel to the wedges 21, 24 in the illustrated embodiment and therefore also parallel to the direction of motion of the casing segments 19 during clamping. While FIGS. 1 to 6 show embodiments in which set screws 25 or adjusting rods 25 or clamping rods are used as actuating elements, FIGS. 7 to 10 show modified embodiments in which other actuating mechanisms are employed. For instance, FIG. 7 shows an embodiment in which the two clamping rings 22 are displaced by moving a lever; for that purpose, at least one link rod or connecting rod 29 is connected to each clamping ring, and the two connecting rods 29 are interconnected by a common tension lever 29. In this embodiment, two respective connecting rods 29 are connected to each wedge ring 22.

[0042] FIG. 8 shows a modified embodiment in which a rotatable adjusting ring 32 is provided as an actuating element that acts on the clamping ring 22, although the clamping ring 22 itself does not rotate along, but rather is displaced axially when rotated. For this purpose, the adjusting ring 32 is secured by a threaded connection 30 on the corresponding housing part or connection adapter 11, 12. On rotation of the clamping ring 32, it rotates axially on the housing part or adapter 11, 12 as a result of the threaded connection 30, so that the clamping ring 22 is thus also displaced with the wedges and the casing segments are clamped. To actuate this rotatable adjusting ring 32, it can be provided on its outer periphery with teeth 31, so that a drive gear can act on the outer periphery of the adjusting ring, for example.

[0043] FIG. 9 shows an embodiment in which a separate rotatable adjusting ring 32 or an adjusting ring assembly is also provided as an actuating element. On rotation of the adjusting ring 32, the clamping or frustoconical ring 22 is displaced axially by the wedges (not shown). For this purpose, the adjusting ring 32 has on its surface facing toward the clamping ring 22 one or more angled faces 33. On its surface facing toward the adjusting ring 32, the clamping ring 22 has corresponding angled faces 34. These angled faces 33 and 34 coact such that, on rotation of the adjusting ring 32, the clamping ring 22 is displaced axially. In this embodiment, in contrast to the embodiment according to FIG. 8, the clamping ring 22 moves only axially, whereas the adjusting ring 32 only rotates. The rotation of the adjusting ring 32 can effected by a set screw (not shown) or also an automated drive.

[0044] Finally, FIG. 10 shows an embodiment in which a rotatable adjusting ring 32 is also provided as an actuating element, although this adjusting ring 32 has several recesses that are formed as guides and in which a respective rolling body, for example a ball 36, is guided. These balls 36 rest against the clamping elements 22, 23, for example the clamping ring 22 or the clamping segments 23. The balls can rest directly against either the clamping ring 22 or the clamping segments 23. Preferably, however, the clamping ring 22 is also equipped with corresponding recesses. This is not shown in the figures. In this case, however, the balls 36 are guided both in the guides 35 of the adjusting ring and in the corresponding guides of the clamping ring that are not shown. In principle, the guides 35 can be tapered over their length in a wedge shape and have a tapering width. Especially preferably, however, they are not only tapered over their width but are also formed as pocket-like guide grooves 35 whose depth decreases from one end of the groove to the other end of the groove (in the direction of the arrow P), so that the balls rest on the rising base of the groove on rotation. In the illustrated embodiment, the balls 36 are shown as guide bodies. Alternatively, however, other rolling bodies such as cylinders or also sliding bodies, in principle, can also be used. Details are not shown. Moreover, it can be seen in the figures that locking fittings 37 are connected to the clamping flanges 20 of the casing segments 19 that coact with complementary locking fittings 38 on the housing parts or the adapters 11, 12 in order to prevent rotation and axial movement. In the illustrated embodiments, projections 37 are connected to the casing segments that are T-shaped and engage in complementarily shaped grooves 38 of the adapters 11, 12. In the illustrated embodiments, the projections 37 are not integrally formed with the casing segments 19 but manufactured as separate parts and fastened with screws 39 to the casing segments 19.

[0045] Moreover, the set screws shown in the illustrated embodiments can also be replaced by other comparable linear actuators, for example adjusting pin, and particularly also by linear drives, such as cylinder piston assemblies or the like.