DE2530552C2 - Eccentric screw pump - Google Patents

Description

The invention relates to an eccentric screw pump with a helically coiled screw rotor, the planet-like in a multi-start hollow helix adapted to its cross-section and its pitch

ίο a stator sleeve rotates, with between the rotor and the opposite part of the hollow helix formed closed helical cavities and conveyed axially from an inlet end to an outlet end of the stator sleeve and in the area of engagement of rotor and stator a large number of replaceable wear parts in axial staggering one behind the other are arranged and the helical surfaces on the stator and rotor by identical, mutually twisted Peripheral surfaces are formed.

Eccentric screw pumps are used for quite different purposes, in particular for conveying pulpy, viscous and solid parts are used. They are self-priming and can generate relatively high pressures that are dependent on the ratio of the stator length to the pitch. That The conveyed material is partially crushed or homogenized, and solid parts are crushed or, if the stator is made of a flexible material such as rubber, it is partially conveyed through unchanged.

The rolling process between rotor and stator results in relatively large local pressure and pressure Frictional stresses, which often lead to very rapid wear on the inner contour of the stator coil to lead. Even with radial advancement of the stator sleeve, the wear is sometimes so great that the stator sleeve has to be replaced after a very short time. The running costs of the pumps are through such repair operations are relatively large.

From US-PS 20 28 407 it is known to be replaceable on the rotor of an eccentric screw pump To attach wearing parts, for example a pack of individual packing rings on the rotor coil or from a wire winding. There were also thin circular disks with an eccentric shape Opening applied to a rotor shaft in such a way that adjacent disks each against one another are twisted. However, the rotor packing always runs in a smooth-surfaced stator cavity with little Oversize until the rotor surface is also correspondingly smooth. To be exchanged can then only use the pack as a whole.

According to GB-PS 12 38 237, the rotor has a large number eccentrically arranged on a rotor shaft, axially braced against one another and glued to one another Rotor disks, which are rotated relative to their neighboring disks by a pitch angle. Also the The stator is there by individual stator disks that are twisted and largely identical to their neighboring disks educated. While the stator disks are made of elastically flexible material, their running surface easily adapts to the shape of the rotor, the glued together rotor disks can be made of hard material, such as ceramic material, exist and should as possible to form a continuously curved curve be thin. A smooth outer surface is obtained after assembly by machining, for example when running in, achieved. Rotor disks and stator disks have different thicknesses and can because of

their smooth, curved running surfaces can only be replaced as a whole. The resulting costs are therefore not significantly different from the costs incurred when replacing the rotor or stator as Whole emerge.

The invention is based on the eccentric screw pump defined at the outset and pursues the task of to improve this pump in such a way that the wear between stator and rotor is reduced and the consequential costs resulting from this wear and tear are reduced.

To solve this problem, according to the invention, the pump is axially adjoining one another in individual ones Pump sections divided, each as axially parallel-IcIe Circumferential surfaces have a stator surface and a rotor surface of the same axial extent, and the Wear parts are provided interchangeably within the pump sections.

The pump sections formed here work together through the series connection and result only as a result of the flow, as occurs for example in conventional eccentric screw pumps The individual pump sections can have the same or different widths, if only within of each pump section, the dimensions of the rotor and stator are matched to one another and at least one replaceable wear element is present, which is individually, so independently of the Parts of the neighboring section can be exchanged for whom local signs of wear can be set. rotor and / or stator can each be made in one piece if a separate wear element can be detached is available. Such wear elements can therefore be manufactured inexpensively in large numbers can be kept in stock without any special effort and easily exchanged as required.

The stator and rotor surfaces cooperating in each pump section have no inclination to the pump axis, which improves the rolling process and reduces overall wear on the engagement surfaces. Ei ⁿ e further reduction of wear is achieved that the rotor receives an improved guiding in the radial planes between adjacent pump sections. Even with a corresponding axial play in the individual pump sections, axial forces that occur can be absorbed at numerous points along the length of the pump. The improved guidance also enables the use of dimensionally stable and abrasion-resistant materials, possibly on the stator and rotor at the same time, and relatively high pressures can be achieved.

It has also been shown that the pump according to the invention compared to conventional eccentric screw pumps results in a much greater protection against dry running. This can be explained by the fact that the Stator cavity of each individual pump section forms a pocket at the bottom in which liquid and Maintain the conveyed mass for a longer period of time and take over the lubrication during start-up. In this way, the Significantly reduced wear and tear and increased the service life of the pump.

According to a first embodiment of the invention, the wearing parts are on the peripheral surfaces of the Arranged rotor and can then easily be replaced without changing the assignment of the rotor and stator changes.

The replacement is particularly easy when the wearing parts are designed as rolling rings and then guided in a rotationally adjustable manner with respect to one another and with respect to the rotor and are axially fixed. At this In a loose arrangement, replacement usually does not require any special specialist knowledge. Through the Rotation of the rolling rings with respect to the rotor causes different rolling processes that result in radial displacements at individual points of the rotor, due to solid particles conveyed along with it and the like, largely avoided. The previous roll-off grinding process is dissolved in that the rolling ring in the stator cavity and rotates on the associated eccentric rotor surface. That way lets the friction against the stator sleeve and thus the wear are further reduced.

Depending on the application, it can be advantageous if the rolling rings at least on their in the hollow helix rollable outer surface have a layer of in particular elastically flexible wear material. In this way, under certain circumstances, the entire resilience, which is necessary for the penetration of solid particles is required, move into the rolling rings, d. H. The stator can basically be made of hard, wear-resistant Material.

According to a further development, a rolling ring has at least two coaxially arranged one inside the other and against one another rotatable ring elements. The rotary setting is placed in the rolling ring, the inner one The ring element can therefore sit firmly on the rotor.

According to a further embodiment, complete rolling bearings are metallic, laterally sealed against one another Inner and outer rings provided. The frictional losses become significant in this way degraded. A metallic cage can also be embedded in the wear material of the rolling ring. is If the rotor is made in one piece, a transversely subdivided or elastic would have to be between the inner ring and the seat Deformable seat ring can be attached to prevent the inner ring from sliding over the steps enable.

The rotor can also be formed by individual cylindrical rotor disks, the thickness of which corresponds to the axial extent a pump section is adapted. The disks must then be eccentric to the rotor axis and to each other aligned and fixed to each other after adjustment. For example, the rotor disks sit with an eccentric recess on a shaft arranged in the rotor axis. Always leave the disks are extraordinary thanks to a single or at most double punching process or broaching process Manufacture inexpensively and then assemble as required to form a rotor of any length.

Corresponding to the disc design of the rotor, the stator sleeve can also consist of individual ring-shaped Stator disks be formed. Instead of or in addition to the rolling rings, the stator sleeve one behind the other individual wear rings, for example in inwardly open grooves of the stator sleeve attach. If the stator sleeve consists of ring-shaped stator disks, then it is advisable to to clamp the wear rings between the stator disks, for example alternating the first stator disks with a Provide smaller and second stator disks with a larger elongated opening.

The material of such wear rings or the material of the rolling rings can vary according to the respective requirements can be chosen almost arbitrarily. It is mainly about smooth running and the penetration of solid parts without substantial crushing, then

elastically deformable material would have to be used there. Where solid parts rubbed or are to be crushed, hard abrasive material such as sintered metal or the like must be used. Wear rings and / or rolling rings of different properties can be used in the same pump Bring use and the otherwise unchanged pump only by replacing such rings from an application convert to the other.

An embodiment is currently preferred in which the rotor and stator are composed of disks of the same width and preferably rolling rings attached to the rotor disks are cylindrical inner and outer surfaces to have. The rotor disks can be made evenly around the circumference thanks to a polygonal profile distributed ribs and grooves be held in a rotationally locked manner on a shaft that is central to the rotor axis. Only this shaft and any tie rods required to brace the stator must then be used for the respective pump length to be provided. The pump can then be made from the inexpensive disks and rolling rings Can be assembled as needed in the shortest possible time, with the seal between adjacent stair-like limited helical cavities on part-cylindrical surfaces takes place.

The drawing shows the invention for example. It shows

F i g. t a longitudinal section through an eccentric screw pump according to the invention,

F i g. 2 shows a cross section through this pump along the line II / II in FIG. 1,

F i g. 3 shows a partial longitudinal section through a modified embodiment of a screw rotor with over Intermediate rings mounted roller bearings and

F i g. 4 a partial longitudinal section through a worm rotor with individual mounted on a shaft Rotor disks with attached ball bearings.

In the case of the eccentric screw pump according to FIGS. 1 and 2, the stator sleeve 10 of the stator 1 is formed by individual stator disks 4, which are arranged centrally to a pump axis 5 and along this by tie rods 6 between inlet port 2 and outlet port 3 are braced.

The identically designed stator disks 4 limit with their cylindrical outer surface 7 and their lateral radial planes 8 individual axially adjoining pump sections 9. Each stator disk has a central to the pump axis 5 arranged elongated opening 11, which at its ends is limited by semi-cylindrical surfaces 12. These are defined by tangentially adjoining flat side surfaces 13 connected and form with these the engagement stator surfaces 12, 13.

Adjacent stator disks are each rotated against each other by a stator pitch angle a step-shaped double helix is thus formed in the individual adjacent openings 11.

In this double helix, a rotor designed as a single-flight step worm runs on an eccentric track 15 in its rotor axis 16 with the eccentricity e like a planet around the parallel pump axis 5. With the The same eccentricity e to the rotor axis 16, the eccentric axes 18 rotate in the individual pump stages attached rotor disks 19, on the cylindrical outer surface 21 each rotatably a cylindrical rolling ring 22 is stored. The rotor disks 19 are also between the individual pump sections 9 by one Rotor pitch angle rotated to each other, but in the opposite direction as the stator disks and with double pitch angle. They are against each other and against a shoulder of the rotor shaft 17 by nuts 23 clamped, which are screwed onto the threaded end 24 of the rotor shaft 17. The rotor shaft 15 is Driven in a known manner via a joint head 25 by a cardan shaft 26.

The outer surface of the rotor shaft 15 is in the manner of a helical gear wheel with a corrugated profile over its entire circumference 27 provided, which is preferably formed by triangular teeth. The same corrugated profile is mounted on the inner surface of the perforations 28 provided eccentrically in the rotor disks 19 and can be achieved by a helical punching or broaching process. The pitch of the screw corresponds, according to the sine line 31, to the gradient of the central screw spiral of the rotor 15. All rotor disks 19 can therefore be in the same alignment position, which is indicated by marks on the rotor disks and the shaft can be determined to be screwed onto this. Individual pump sections can be set up one after the other Assemble stator disk 4, rotor disk 19 and rolling ring 22. The rolling rings 22 should be pulled up at the same time as the rotor disks 19.

In contrast, the stator disks 4 can also be applied retrospectively with their long circular openings 11. You are by tie rod 6 between inlet pipe socket 2 and outlet pipe socket 3 or between braced separately to be applied end flanges after they are over the rolling rings 22 in the circumferential direction have aligned on the rotor 15. For radial centering, a cylindrical sleeve can optionally also be placed over the Stator disks are drawn.

The openings 11 of the stator disks 4 form a hollow one that extends through the entire stator Double helix. In each pump section, the opening 11 of the outer surface 21 of the rolling ring 22 and 32 of the rolling ring 22 divided into two crescent-shaped cavities 33 at two sealing lines 30, of which the upper one in Fig. 2 has the minimum size, the lower the maximum size.

When the pump is running, the rotor disk 19 moves back and forth with the rolling ring 22 between the two end positions with a pump stroke h = 4e. While the lower cavity 33 shrinks and ejects transport goods, the upper cavity enlarges and sucks in transport goods. On both radial outer parts of the helical double helix, individual cavities are thus formed in the manner of bubbles, which move on a stepped helical path along the pump axis 5 from the inlet connector 2 to the outlet connector 3.

Instead of the helical corrugated profile 27 of the rotor shaft 15, one can choose such a profile, which runs parallel to the rotor axis 16 when the division of the individual teeth by the width of the Disc-related division corresponds to. You then only have to move the rotor disks 19 by a pitch angle slide open twisted.

According to FIG. 3, the outer surfaces 21 of the individual pump sections are molded onto a one-piece rotor 15a for the sake of clarity, the gradients with approximately the same increments in one common axial plane are folded. The rolling ring arrangement is formed by individual complete ones Ball bearings 34 with inner rings 35, outer rings 36 and lateral seals. So that the inner ring 35 pushed onto the rotor outer surface 21

can be, a separate seat ring 37 is inserted between each. Such a seat ring can, for example, be made up of a metallic one that is transversely divided into two half rings Ring are formed or consist of a flexible material such as rubber that extends over the Can push shoulder surfaces away on the respective rotor outer surface 21.

According to FIG. 4, rotor disks 19a of the rotor i5b with an eccentric bore are seated on a rotor shaft 17a that is central to the rotor axis 5 and engage with a wedge shoulder 38 in a helical keyway 39 of the rotor shaft. If there is only one wedge shoulder, it must be attached at another angle to the eccentric hole. However, as explained with reference to FIGS. 1 and 2, a large number of key lugs 38 and keyways 39 can also be provided in order to enable otherwise identical rotor disks to be easily repositioned. The ball bearings 34 can according to FIG. 4 can be pulled onto the rotor disks 19a without intermediate rings 37.

Instead of placing the rotor disks 19a or 19 on a rotor shaft, they can also individually, for example through provided on its circumference screws or the like are directly connected to one another. Unless the Outer rings 36 are intended to run directly on the inner contour of the stator coil, they can be coated with a layer 29 be encased from wear material.

Wear parts do not necessarily have to be rotatably supported as rolling rings or attached to the rotor, they can also be provided on the stator sleeve 10. In the latter case, they should at least be circumferential are held by frictional forces. Appropriately, they are in grooves on the inside of the stator set, for example glued in place. If possible, they should also have such dimensional stability that they already thereby held in their position. They can be in annular grooves or in the middle of each stator disk be attached inside at the edges of such annular grooves and between adjacent stator disks let clamp. Naturally, greater protection is provided by those attached to the rotor and stator Wear parts designed according to the required operating conditions, with rolling rings on the rotor to be favoured. The remaining parts of the rotor and stator can be exposed to wear and tear in this way be kept away entirely. The service life of the pump is therefore in principle unlimited, provided that wearing parts are replaced from time to time.

The contour surfaces or engagement surfaces of the stator and rotor can in principle be made of hard material are manufactured, provided that this ensures the seal along the sealing lines 30 in the openings 11 remain. This is the case, for example, when lubricating and sealing viscous liquids without coarse impurities are to be promoted.

However, if larger hard solid particles are trapped in the pumped medium, it may be advisable to to provide some compliance to at least one of the engagement members. It can also be on Stator about relatively hard rubber can be provided, while one is relatively on the rolling rings attaches soft rubber. As a result, the peaks of the pressure and friction forces are reduced and the Reduced load on the stator. Mainly by shifting the wear to wearing parts such as rolling rings, the stator can be made of any hard and wear-resistant material, or on the inside with coat a suitable lining material.

Since the mass of the wearing parts is considerably smaller than the mass of the stator 1, one can for the wearing parts or rolling rings 22 use the respectively required and possibly also expensive special material, depending on the type of medium conveyed, the sealing effect or conformability, abrasion or Comminution are significant. If it is mainly about the size reduction, then z. B. abrasive materials such as sintered metal or solid hard steel are used. Stand waterproofing, lubricity and low-noise running in the foreground, then high-quality plastics such as polytetrafluoroethylene can be used. Resistance to chemical attack can also be important when choosing a material and conventional bearing materials such as bronze can be used. It is also possible to use rolling rings 22 different properties can be used simultaneously in the same pump. You can go to Insert rolling rings with a larger outer diameter for a given operating time, until finally the stator is largely consumed.

It is not absolutely necessary to fine-tune the inner contour of the stator 1, since it may can also be made as a casting, for example from dense gray or cast steel, whereby one then initially Rolling rings made of abrasive material, if necessary with additional abrasives, are used around the inner contour to smooth.

Just as different materials can be combined, so can the width of the individual pump sections 9 and thus also the local slope of the possibly deformed sinusoidal line or the associated stepped helix change. A particular advantage of the design according to the invention is that even with the same width of the pump sections 9, the pump length can be changed at will if you only the rotor shaft 17 and the tie rod 6 exchanged, irr. but the rest of the number of rotor and used Stator disks 19.4 changes due to the width of the part-cylindrical sealing surfaces becomes extraordinary Wear resistance and thus a significant increase in service life with just one Set of wearing parts achieved. Since the hollow helix of the stator in each pump section has a special one A pocket in which water and conveyed goods can be kept for a long time during breaks in operation will be exceptional Safety against dry running is achieved and start-up after a standstill is made easier.

For this purpose 3 sheets of drawings

Claims (10)

Patent claims: 1. Eccentric screw pump with a helically coiled worm rotor, which is like a planet in a multi-start hollow helix adapted to its cross-section and its pitch Stator sleeve rotates, being closed between the rotor and the opposite part of the hollow helix helical cavities formed and axially from an inlet end to an outlet end the stator sleeve and in the meshing area of the rotor and stator a large number of exchangeable Wear parts are arranged one behind the other in an axial staggering and the screw surfaces formed on the stator and rotor by identical, mutually twisted circumferential surfaces are, characterized in that the pump in individual axially contiguous Pump sections (9) is divided, each as axially parallel peripheral surfaces a stator surface (12, 13) and a rotor surface (21, 32) have the same axial extent, and that the wearing parts (22, 34) are provided interchangeably within the pump sections (9). 2. Eccentric screw pump according to claim 1, characterized in that the wearing parts (22) are arranged on the peripheral surfaces (21) of the rotor (15). 3. Eccentric screw pump according to claim 2, characterized in that the wearing parts (22) are designed as rolling rings 4. Eccentric screw pump according to claim 3, characterized in that the rolling rings at least on its outer surface (32) which can be rolled off in the hollow helix (12, 13), a layer of in particular have elastically resilient wear material. 5. Eccentric screw pump according to claim 3 or 4, characterized in that a rolling ring (34) at least two coaxial ring elements arranged one inside the other and rotatable relative to one another (35,36) (Fig. 3,4). 6. Eccentric screw pump according to claim 5, characterized in that complete rolling bearings (34) provided with metallic inner and outer rings (34, 35) which are laterally sealed against one another are. 7. Eccentric screw pump according to one of claims 1 to 6, characterized in that the Rotor (15) 'π individual cylindrical rotor disks (19) gel ». t. their thickness of the axial extension of a Purr. nsection (9) is adapted. 8. Eccentric screw pump according to claim 7, characterized in that the rotor disks (19) with an eccentric recess non-rotatably on a shaft arranged in the rotor axis (16) (17) sit. 9. Eccentric screw pump according to one of claims 1 to 8, characterized in that the Stator sleeve (10) is formed from individual annular stator disks (4). 10. Eccentric screw pump according to one of the preceding Claims, in particular according to claim 9, characterized in that individual wear rings one behind the other on the inner surface of the Stator sleeve are attached. U. Eccentric screw pump according to claim 10, characterized in that the wear rings zwi between the stator disks are clamped.