EP3408539A1

EP3408539A1 - Piston for a rotary piston pump

Info

Publication number: EP3408539A1
Application number: EP17702831.3A
Authority: EP
Inventors: Thomas Hinners
Original assignee: Hugo Vogelsang Maschinenbau GmbH
Current assignee: Hugo Vogelsang Maschinenbau GmbH
Priority date: 2016-01-28
Filing date: 2017-01-27
Publication date: 2018-12-05
Anticipated expiration: 2037-01-27
Also published as: AU2017213147A1; US10982671B2; EP3408539B1; DE202016100419U1; BR112018015305A2; JP2019503454A; MX2018009213A; AU2017213147B2; KR20180123019A; US20190048872A1; CN108700063A; WO2017129794A1; CA3013104A1; MY198166A

Abstract

The invention relates to a rotary piston pump comprising a housing with a housing interior, an inlet opening, and an outlet opening; a first rotary piston which is mounted within the housing interior in a rotational manner about a first rotational axis; and a second rotary piston which is mounted within the housing interior in a rotational manner about a second rotational axis. The first rotary piston and the second rotary piston engage into each other in a region between the first and the second axis and displace liquid. The first rotary piston has a frame assembly which comprises multiple mutually spaced plates and is at least partly filled and coated with a polymer material.

Description

Piston for a rotary lobe pump

The invention relates to a rotary lobe pump, comprising a housing having a housing interior, an inlet opening, through which liquid can flow into the housing interior, an outlet opening through which liquid can flow out of the housing interior, a first rotary piston which rotates about a first axis of rotation within the housing interior is mounted, and a second rotary piston which is rotatably mounted about a second axis of rotation within the housing interior, wherein the first rotary piston and the second rotary piston in a region between the first and the second axis intermesh and displace liquid. Another aspect of the invention is a method for producing a rotary piston for such a rotary piston pump and a rotary piston for such a rotary piston pump.

Rotary lobe pumps are conveyors for fluids that are mainly used for low or high viscosity fluids. Rotary pumps operate on the principle that two counter-rotating rotary pistons rotate about two spaced apart, parallel axes and mesh in such a way that each engages a rotary piston of a rotary piston in a rotary piston recess between two rotary pistons of the other piston. As a result, the liquid in the central region between the two axes is displaced by the meshing and in the two outer peripheral regions outside the two Rotary axes in delivery chambers, which result from the rotary piston recesses in sealing the two rotary piston blades lying around it or their rotary piston blade tips against the housing wall, are conveyed from the inlet to the outlet opening.

Rotary pumps can be equipped with rotary pistons, which have two, three or more rotary vane.

Rotary lobe pumps are used in a specific application to deliver particulate-laden fluids. A problem in the promotion of particle-laden liquids is the high wear occurring on various pump components. As a matter of principle, rotary lobe pumps are better suited than other types of pumps for pumping particle-laden liquids, but they are also subject to high levels of wear.

This wear is caused by particles that either pinch between the rotary pistons or become trapped between the outer ends of the rotary vanes and the housing wall and thereby cause indentations or grinding marks in the surfaces of the housing wall or the rotary pistons.

Rotary pistons are produced according to the prior art from a metal and in this case manufactured so accurately that efficient delivery at low leakage rates is possible. It is known to equip rotary pistons with a superficial rubber layer in order to counteract wear effects in the conveying of particle-laden liquids. The underlying effect of this measure is that the rotary pistons are due to the rubber layer to a limited extent suitable to penetrate particles that are trapped between the rotary piston or between the rotary wing and housing wall, by short elastic or plastic deformation in their rubberized surface without suffering any permanent or serious damage. As a result, the formation of deep impressions, wear marks and other wear effects can be prevented and the wear behavior of rotary lobe pumps in the promotion of particle-laden liquids can be improved.

However, the problem with such constructed rotors different effects. On the one hand, in the operation of such rotary lobe pumps, it is observed that the rubber layer separates from the rotary piston and can break off, in particular when fluids with sharp-edged or large particles are conveyed and these have pressed themselves several times into the rubber layer of the rotary piston. By such smaller or large-scale delaminations of the rubber layer on the one hand, the protective effect of Rubber layer locally reduced or eliminated, on the other hand, the pump efficiency is reduced because the desired sealing effect between the rotary piston and between the rotary piston and the housing wall is no longer reliably achieved. Due to the production-related shrinkage of a rubber layer on a rotary piston high precision and accuracy of fit of the rotary piston is achieved in particular with a thin rubber pad, which has a manufacturing technology reliably controllable shrinkage. However, it has been observed that the problem of delamination of the rubber layer can be positively influenced by increasing the thickness of the rubber layer. There is therefore an optimization problem in that although by increasing the thickness of the rubber layer, the wear resistance against delamination effects can be increased, but at the same time the controllability of the manufacturing accuracy is reduced and thereby either the reject rate in the production of rotary piston is increased or the precision of the fit of Rotary piston is reduced, resulting in a reduction of the conveying efficiency. The invention has for its object to propose an improved rotary lobe pump for promoting particle laden liquids within this optimization problem.

This object is achieved by a rotary piston pump of the type described above, in which the first rotary piston has a framework arrangement comprising a plurality of spaced apart plates and the framework assembly is at least partially filled with a polymer material and at least partially sheathed.

With the inventive construction of the rotary piston of the rotary piston pump, the problems in the prior art are overcome by a completely different internal structure of the rotary piston is realized. Instead of a metallic core, which is provided with a more or less thick rubber layer, the rotary piston is constructed by a plurality of spaced-apart plates as a framework arrangement. This framework arrangement is at least partially enveloped and filled with a polymer material. The rotary piston designed according to the invention is designed in particular such that, apart from a central opening for receiving a drive shaft, it has no air-filled cavities, that is to say it is filled in its interior either with plate material or with polymer material. The plates are preferably arranged such that they are aligned with their surface perpendicular to the axis of rotation of the rotary pistons. The plates therefore define in particular the cross-sectional geometry of the rotary piston, by having a corresponding inner contour and a corresponding outer contour. The inner contour defines the inner central opening of the Rotary piston with which the rotary piston is received on a drive shaft. This inner recess is preferably designed to transmit a torque, for example by having a polygonal cross-sectional geometry or is embodied in another form for a positive torque transmission. It is particularly preferred that the plates directly define the geometry of the inner, central opening of the rotary pistons, that are not coated in the region of this inner opening of the rotary piston with the polymer material in order to achieve a defined angular position of the rotary piston relative to the drive shaft, the free of elastic influences of the polymer material. Alternatively, the rotary piston according to the invention may have a hub with an internal opening through which a drive shaft can be inserted or which can be connected in a torque-resistant manner to a drive shaft in another way. The plates have in this case an inner central opening, with which they can be mounted on the outer geometry of this hub and preferably fixed torque-resistant. It is further preferred that the plates on the outer surface of the rotary piston are completely coated with polymeric material so as to avoid contact of the housing with the plates in contact with the housing wall or the other rotary piston.

In principle, it should be understood that the plates are preferably formed of a material which has a higher rigidity, ie a lower elasticity, and a higher strength than the polymer material. Preferably, the plates may be made of, or at least partially comprise, a non-metal to reduce the weight of the piston.

With the rotary piston constructed in this way, on the one hand, a substantially more stable connection between the carrier material and the polymer material is achieved by providing the carrier material as a framework arrangement consisting of several plates. The infiltration observed by the inventor starting from damage sites, the boundary layer between the polymer material and the metallic core in rotary lobes according to the prior art can no longer take place in the inventive design of the rotary piston, since the boundary layer between the framework arrangement and the polymer material occupies a much larger area and also can be formed substantially with surfaces that are perpendicular to the axial direction. This surface orientation is much less sensitive to such submarine migration and delamination than radially outwardly directed peripheral surfaces. Another advantage of the rotary piston according to the invention is the favorable shape stabilization by the framework arrangement, which counteracts shrinkage of the polymer material in the course of its crosslinking. Under networking is here in the sense of Invention to understand a process in which molecules combine with each other by the formation of new chemical compounds or change by replacing a first type of chemical compound with another type of chemical compound. In particular, such crosslinking is to be understood as meaning polymerization or vulcanization.

In addition to the advantages sought according to the invention, it has also been shown that the rotary pistons designed according to the invention have a lower weight than rotary pistons of known design, whereby the total weight of a rotary piston pump according to the invention is reduced compared to conventional rotary piston pumps. A further advantage is that the rotary pistons according to the invention are produced with a lower use of metallic material at the expense of a higher proportion of the polymer material, whereby the manufacturing costs are reduced in terms of material costs.

According to a first preferred embodiment it is provided that the plurality of spaced-apart plates are aligned parallel to each other and / or that the distance between each two spaced-apart adjacent plates is the same.

In principle, two, three, four or even more plates can be used to make a rotary piston and the space between these plates can be filled up accordingly with polymer material. It is to be understood in principle that the framework arrangement from the plates is preferably completely filled with polymer material and preferably the outer surface of the rotary piston is completely enveloped by polymer material, whereas the inner opening of the rotary piston, which serves for the torque-transmitting power transmission from a drive shaft to the rotary piston, preferably is not enveloped with polymer material. By aligning the plates at a uniform distance from each other, a simplified production is achieved by systematically equal distances of the plates to each other. The parallel orientation of the plates causes a uniform layer thickness of the intervening polymer material and thus avoids distortion in the outer geometry of the rotary piston as a result of polymerization or vulcanization processes or other cross-linking effects.

According to a further preferred embodiment, it is provided that between each two plates, a spacer element is present, which extends over a predetermined height above a plane of the plate and pointing away from him at the plate plane End are in contact with another plate, in particular an adjacent plate, wherein the spacer element is preferably made by angled deformation of a portion of the plate. The production of a rotary piston according to the invention can be carried out in particular such that a plurality of plates, which form the framework arrangement of the rotary piston, are positioned in a mutually defined position in a mold and then the filling / sheathing with the polymer material takes place within this mold. It is advantageous if the definition of the distance between the individual plates is effected by separate spacer elements or by the geometry of the plates themselves, for example by a spacer element is formed on the plates or inserted between two plates. These spacers form the function of a spacer between the plates. In principle, a single spacer element between two plates can fulfill this function and position the plates in a defined position relative to one another and a defined distance from one another. In addition, a position definition of the plates can be made to the axis of rotation of the rotary piston, for example by appropriate position support against the hub of the rotary piston. Instead of a one-piece spacer element, the function of distancing and, if appropriate, positional positioning of the plates can also be provided by a multi-part spacer element, for example a spacer element which consists of two, three, four or more spacer elements which are inserted between two adjacent plates. In this case, at least three spacer element pieces are preferred so that a defined angular position of the plates relative to one another, in particular a parallel alignment of the plates relative to one another, is achieved by the multi-part spacer element. The number of spacer elements, which form a spacer element between two plates, may in particular correspond to the number of rotary vanes of the piston, so that in the case of rotary lobes with 2, 3, 4, 5 or 6 vanes corresponding spacer elements are used which consist of 2, 3, 4, 5 or 6 spacer pieces are composed. A spacer element can furthermore preferably be formed integrally on a plate, that is to say be embodied in one piece with the plate.

It is particularly preferred that the spacer element is made by angled deformation of a portion of the plate. This is a preferred manufacturing method for the spacer elements, which is particularly suitable for cold or hot deformable ble materials from which the plates are made. Here, in particular, a one-sided formed on the plate web can be angled such that it is at an angle of about 90 ° to the plate surface and thereby represents the spacer element. Likewise, a web portion, which is connected to both sides of the plate, are deformed by a deformation out of the plane of the plate, so that he, for example, himself rises in a V-shaped contour over the plane of the plate and represents the spacer element.

According to a further preferred embodiment it is provided that the plates are made of metallic material sheets and / or the polymer material is a rubber-elastic material. The production of the plates from a metallic material allows a particularly robust framework arrangement which has grown the operating forces, in particular the forces required for torque transmission from the drive shaft to the rotary piston. The provision of the plates of a metallic material in the form of sheets in particular allows cost-effective production of the plates by punching or laser cutting the plates of a semi-finished material in the form of sheets and the production of the spacer elements by cold working of a corresponding section or corresponding to several sections of these sheets , The polymer material may in particular be a rubber-elastic material which tolerates the elastic impression of particles without damaging the polymer material. These are in particular rubber-based polymer materials which are produced by a vulcanization process, but other materials similar to such a rubber property can also be used for the rotary piston according to the invention.

Still further, it is preferred that the polymeric material is provided by a prefabricated polymeric member intercalated with aligned apertures in the panels and a polymeric material portion formed by flowable polymeric material at least in the flowable state of the panels and the prefabricated polymeric component partially enveloped and thereafter crosslinked to a solid state. According to this embodiment, the polymer material is formed by two different proportions. The first part is a prefabricated, already cross-linked component, which is passed through corresponding openings in these plates after assembly of the plates. This prefabricated polymer component is then enveloped by a second portion of polymeric material and thereby fixed in position relative to the panels. The two parts form a coherent polymer structure. The advantage of the thus formed rotary piston is that on the one hand a large amount of polymer material can be realized in the rotary piston, on the other hand it is avoided that the rotary piston is made by networking a large proportion of polymer material within the framework arrangement and thereby has a large and poorly predictable shrinkage. Instead, an already cross-linked polymer component is used to fill up a large proportion of the volume within the framework assembly with polymeric material, and only a minor one Volume fraction within the framework arrangement then filled / enveloped with a flowable polymer material, which then crosslinked and in this case undergoes a shrinkage. In this case, it is particularly preferred for the prefabricated polymer component and the polymer material fraction to consist of the same polymer material, thereby achieving a particularly good bond between the prefabricated polymer component and the polymer material fraction enveloping it. It is further understood that several prefabricated polymer components can be used in a rotary piston. Thus, for example, it is preferred that the plates have a plurality of openings distributed over the circumference, so that a plate has, for example, a cross-sectional geometry that is similar to a spoke wheel and the several cavities formed thereby between the spokes are filled by correspondingly contoured polymer components.

According to a further preferred embodiment it is provided that the mechanical connection between the polymer material and the plates by adhesive bonding, by positive engagement between openings in the plates, which are filled with polymer material, or by frictional connection by means of clamping elements which interconnect the plates and the polymer material tense, is formed. In principle, three essential mechanisms are available in order to achieve a connection between the polymer material and the plates or the framework arrangement in the design of the rotary piston according to the invention. An adhesive bond can be achieved directly between the polymeric material and the panels, to reinforce or to produce such an adhesive compound, the framework assembly can also be coated with a primer or adhesive other than the polymeric material prior to adding the polymeric material. This adhesive compound may correspond in particular to the adhesive connection between the rubber and the metal part of such rubber-metal elements used in rubber-metal elements in the field of vibration damping. Furthermore, a positive connection between openings in the plates and the polymer material passed therethrough can be achieved. These openings in the plates can deliberately be provided for this purpose, for example in the manner of the disk structure in the form of a spoke wheel already explained, but other structures, such as perforated plate elements or the like, are also advantageous for such a positive locking effect. Finally, a frictional connection between plates and polymer material can be achieved, that is, a liability, which is achieved by a frictional force between the plates and the polymer material, can be effected. The force required for this frictional force normal force can then by a tension of the plates and the Polymer material can be achieved, for example, by perpendicular to the plane of the plate screws are provided between the outer plates of the rotary piston, which compress these two outer plates in the axial direction. In principle, a single one or more of these linkage mechanisms may act simultaneously to make the connection between the plates and the polymeric material.

It is even further preferred if the second rotary piston has a framework arrangement which comprises a plurality of spaced-apart plates and the framework arrangement is at least partially filled with a polymer material and at least partially encased. According to this embodiment, the second rotary piston as well as the first rotary piston is constructed with a skeleton assembly of a plurality of plates and a polymer material. In principle, it should be understood that the first and the second rotary piston of the rotary piston pump can be identical and also the second rotary piston can be designed in accordance with the previously explained embodiments. Still further, it is preferred if the first and / or the second rotary piston has an internal non-circular opening formed by an opening in the plates not filled with the polymeric material and the first and second rotary pistons respectively via first and second shafts , which is arranged in this opening, is rotatably mounted. Such a recess or opening in the rotary piston makes it possible to arrange the rotary pistons in a form-fitting manner on a shaft which is correspondingly congruent to the opening and to set it in rotation by means of this shaft. Alternatively, the plates may be positively secured to a hub, which in turn is mounted on the shaft, for example non-positive or positive. The recess or opening is formed by corresponding recesses or openings in the plates of the framework arrangement, which consequently cause a transmission of the torque from the drive shaft to the framework arrangement. Thus, for example, a polygonal recess may be provided in the plates or the rotary piston, in particular, a hexagonal opening is suitable, which cooperates with a corresponding hexagonal shaft or hexagonal notch. In principle, however, other embodiments for positive locking are possible, for example, keyways in an otherwise circular recess, which are designed for positive engagement with a corresponding cylinder portion of the shaft or hub with a corresponding key. In principle, it is preferred if both rotary pistons are connected in a torque-locking manner to a drive shaft and these drive shafts are synchronized via an external gear, so that both rotary pistons are driven synchronously but independently of one another. In other embodiments, however, only one of two rotary pistons are coupled torque-coupled via a shaft and driven, and the other rotary piston is set by the engagement with this rotary piston in a synchronous rotation, without being driven by a shaft itself. Consequently, this other rotary piston only has to be rotatably supported, so that a circular recess without torque transmission to the shaft is also possible here.

According to a further preferred embodiment, it is provided that the first and the second rotary piston having at least two rotary wing, which extend in a helix along the outer periphery of the rotary piston and that the plates have a corresponding geometry with at least two rotary lobes, all plates are geometrically equal and the helical profile is effected by means of a non-circular, helically extending outer contour of a drive shaft or hub which is in positive engagement with a central recess of the plates, or the plates are subdivided into at least two sets resting on a shaft or hub with a rectilinear, non-circular outer contour are pushed, wherein the plates within a set a matching geometry and the plates of two different sets have a different geometry such that the angular position between a not Circular contour of a central opening and the rotary vane between the plates of two different sets is different from each other. In principle, the rotary vane wings may extend along an axially aligned line that is parallel to the axis of rotation of the rotary piston. Rotary pumps with such rectilinear rotary vane typically show a pulsation in the conveying operation, which are due to the defined promotion in the delivery chambers, which form between the rotary wing and the housing wall, caused. In contrast, the pulsation of the promotion can be reduced or avoided altogether, when the rotary vane along a helical line. This embodiment is particularly suitable for rotary pistons with more than two rotary lobes, so three, four or mehrflügeligen rotary piston, since in this embodiment, the sealing of the chambers between the rotary lobe is reliably achieved to the housing. It is preferable for the contour of the rotary piston to be predetermined by the framework arrangement as far as into the rotary piston wings. In this case, in this preferred embodiment, the scaffold assembly must map or have the helical course of the rotary wing. This can be achieved according to the invention by two alternative embodiments. On the one hand, the plates which form the framework arrangement of a rotary piston can be geometrically identical. But because of the pictured in a plate rotary lobe relative to the offset in the image of the same rotary wing in a plate adjacent thereto by a predefined angle, which is calculated from the pitch of the helical line and the distance between the two plates, the plates must be arranged in this case at an angular offset to each other on the drive shaft be. This can be achieved with the use of identical plates by the outer contour of the drive shaft or hub also has a non-rotationally symmetrical contour with a helical course. Such a course of the outer contour of the drive shaft or hub makes it possible to carry out the plates of the scaffolding arrangement identical and with an angular offset to each other in the rotary piston such that this helical course of the outer contour is mapped congruent in the rotary piston. The consequence of this arrangement is a helical course of the rotary-piston vanes, wherein the pitch of the helix of the rotary-piston vanes corresponds to the pitch of the outer contour of the drive shaft or hub. The advantage of this embodiment is the use of identical plates, which enables their production in a cost-effective mass production.

As an alternative to this embodiment, two or more different sets of plates can also be provided in order to produce the framework arrangement of a rotary piston of the type according to the invention. In this embodiment, the drive shaft or hub is provided with a non-circular outer contour, which, however, is rectilinear, ie parallel to the longitudinal axis of the drive shaft, and consequently has no helical course. On this drive shaft or hub plates of different geometry are now pushed, these plates differ in that the angular position of the rotary wing with respect to the non-circular contour of the central recess of the plate is different from each other. This allows, for example, the following production and procedure for a rotary piston with a helical rotary vane: The rotary piston is designed as a three-leaf rotary piston, that is, each plate has three rotary lobes, which are offset by an angle of 120 ° to each other. The first set of plates is provided with a keyway in a central circular recess which is in angular position zero to a rotary wing. A second set of plates is made having an angular position of 40 ° of the keyway to the rotary vane. A third set of plates is made which has an angular position of 80 ° between the keyway and the rotary vane. Now, the skeleton arrangement of this rotary piston can be constructed so that successively a plate of the first set, a plate of the second set, a plate of the third set, and then again a plate of the first set, followed by a plate of the second set and a plate of the third set are each arranged to each other so that the keyways of the plates are aligned with each other. The result is a helix of the rotary wing, which is defined here by a total of six plates. An advantage of this embodiment is the simple and inexpensive production of the drive shaft or hub, which can be designed as a conventional cylindrical shaft or hollow hub with keyway in the Au ßenumfangsf laugh or with a hexagonal outer surface.

Another aspect of the invention is a method of manufacturing a rotary lobe for a rotary lobe pump comprising the steps of forming a framework assembly by providing a plurality of spaced apart plates, at least partially enveloping the plates with a polymeric material in a flowable state, and creating a bond between the framework assembly and the polymeric material by crosslinking the polymeric material.

The method is suitable for cost-effective production while avoiding a high proportion of metallic material for a rotary piston with a high accuracy of fit and favorable abrasion and delamination properties. The polymer material is in particular a rubber-elastic material, such as a rubber-based rubber material into consideration, which is brought by vulcanization in its mechanically strong form and in adhesive connection to the skeleton assembly. The method can be developed by positioning the plates parallel to one another by spacer elements formed on the plates.

Still further, it is preferable if the plates are made of sheet metal and that a spacer is formed between two plates, for example by angling one or three sections of the plate. Finally, the method may be further developed by molding the polymeric material by preforming a polymeric component by crosslinking a first portion of the polymeric material prior to forming the scaffold assembly, placing the prefabricated polymeric component in aligned apertures in the panels, and at least partially encasing the panels and the polymeric component a second portion of the polymeric material in the state of a flowable polymeric material, and curing the second portion of the polymeric material to a solid state.

Another aspect of the invention is a rotary piston for a rotary pump, which is characterized by a framework arrangement comprising a plurality of spaced-apart plates, wherein the framework arrangement with a polymer material at least partially filled in and at least partially encased. This rotary piston is on the one hand cost-effective, on the other hand, accurate fit and particularly resistant to abrasion, wear and delamination of the polymer material from the framework arrangement. The rotary piston can in particular be further developed as has been described above for a rotary piston which is used in a rotary piston pump according to the invention. Furthermore, the rotary piston can be developed by being manufactured according to a method of the type described above.

A preferred embodiment of the invention will be described with reference to the accompanying figures. Show it:

1 is a perspective view of a rotary piston according to the invention obliquely from the front,

1 a is a view according to FIG. 1 without polymer material,

2 is a perspective view of the embodiment of FIG. 1 obliquely from the side,

2 shows a view according to FIG. 2 without polymer material, FIG. 3 shows a frontal view of the embodiment according to FIG. 1, FIG. 3 a shows a view according to FIG. 3 without polymer material, FIG. 4 shows a side view of the embodiment according to FIG. 1, FIG. 4a is a view according to FIG. 4 without polymer material

Fig. 5 is a perspective view obliquely from the side of the hub body of the

Embodiment according to FIG. 1,

6 is a front view of a scaffold plate of the embodiment of FIG. 1,

7 is a perspective view of a scaffold plate of the embodiment of FIG. 1,

Fig. 8 is a front view of a spacer element of the embodiment according to

Fig. 1, and 9 is a perspective view of a spacer element of the embodiment of FIG. 1st

As a preferred embodiment, a three-winged rotary piston with twisted rotary wings 41, 42, 43, which follow a helix, shown. Basically, it should be understood that the invention is applicable to rotary pistons with straight rotary lobes or spiral lobes or lobes having a geometry different therefrom and can be used for rotary lobes having two, three, four, five or more rotary lobes.

The rotary piston according to the invention has a rotary piston hub 10, which is typically made of a metallic material. The rotary piston hub has a cylindrical inner geometry with a groove 1 1 for torque-fixed connection to a drive shaft by means of a feather key. In principle, it is also possible to use other shaft-hub connections which are suitable for transmitting torque from the shaft to the hub, for example polygonal shafts which interact with a corresponding internal geometry of a polygonal hub, conical connections which form the shaft by means of a non-positive connection manner connect with the hub, gears between shaft and hub and the like. The rotary piston hub is surrounded by three rotary lobes 41-43, which are arranged with a 120 ° pitch around the circumference of the rotary piston hub and in the axial direction of the rotary lobe winding about 60 ° in the circumferential direction along a helical line. Basically, it should be understood that the amount of twisting should be selected depending on the number of blades to achieve pulsation-free operation, a leak-free pumping action, and a back-flow protection of the pump in each rotational position of the rotary pistons. In the case of double-winged pistons, a twisting of the blades over 90 °, for three-leafed pistons a twisting of the blades over 60 °, for four-leafed pistons, a twisting of the blades over 45 ° and generally a twisting of the blades over 180 ° divided by the number of blades should be maintained or not exceeded.

The rotary lobes are coated with a polymer material on their flanks as well as on their tips and forehead sides. This polymer material is also partially formed in the interior of the rotary wing, the exact design will be explained in detail below.

The polymer material is preferably a rubber-elastic material is used, which may be in particular cured by vulcanization rubber material. 1 a, 2 a, 3 a and 4 a, a scaffolding construction can be seen, which serves to produce a torsionally rigid connection between the rotary piston wings and the rotary piston hub. The framework construction comprises a plurality of scaffold plates 20a, b, c, d,... Which in principle correspond to the cross-sectional contour in an axial cross-section of the rotary piston, but are smaller in their dimensions than the cross-sectional dimension. Each scaffolding plate thus has three wings 21, 22, 23, which are arranged at a pitch of 120 ° to each other. Furthermore, each scaffold plate has a central recess 24, see Figures 6 and 7. This central recess is designed such that it provides a torque-fixed connection between see the scaffold plate and the rotary piston hub. In the preferred embodiment, this is achieved by the recess is substantially circular and has three circumferentially distributed grooves 25 which cooperate with three congruent thereto formed webs 12, 13, 14 form-fitting manner on the outer surface of the rotary piston hub, as shown in Figure 5 , Basically, it should be understood that the torque-fixed connection between scaffolding plate and rotary piston hub can be carried out in various ways, alternatively to the embodiment shown here, embodiments with a single groove and a corresponding single web can be formed, it can alternatively other ways of connecting with a toothing or be carried out the same. In the illustrated embodiment, the circumferential length of the grooves in the scaffolding plate is approximately 60 °, so that a uniform distribution of the three recessed peripheral portions and the three protruding peripheral portions of the central recess 24 results in the scaffold plate. The groove-shaped recess is in each case arranged in the region of the rotary-piston vanes in order to allow a favorable utilization of material and a narrow design of the framework plate in the region between the rotary-piston vanes.

Each scaffolding plate further comprises a circular recess 26, 27, 28 in each rotary vane. The scaffold plates of the rotary piston according to the invention are therefore designed with specification of the outer contour of the rotary piston and a direct contact to the rotary piston designed torque-resistant connection with a maximum material savings.

As can be seen from FIG. 5, the webs 12, 13, 14 extend in the axial longitudinal direction along the peripheral surface of the rotary piston hub along a helical line which corresponds to the helical course of the rotary-piston vanes. The inner framework of the rotary piston according to the preferred embodiment can be constructed from a number of scaffold plates, all of which have the same design. In addition to this preferred embodiment, other embodiments of the invention appropriate rotary piston conceivable and advantageous in certain applications. Thus, for example, an embodiment may be advantageous in which the webs are designed in a straight line in the axial longitudinal direction of the rotary piston hub. In connection with the scaffolding plates depicted in FIGS. 6 and 7, in this embodiment a rotary piston with straight rotary-piston wings results. Furthermore, in the formation of such a rotary hub with straight webs, a helical course of the rotary wing can be achieved by alternately using scaffolding plates, which are designed differently. In this case, this different design must consist in that the angular offset between the grooves 25 on the one hand and the rotary piston blade sections 21, 22, 23 on the other hand differs in the different embodiments of the scaffold plates. The angular difference results here from the desired slope of the rotary vane along the helical course and the axial distance of the scaffold plates on the rotary piston hub.

As can be clearly seen in particular from FIGS. 2 a and 4 a, the rotary piston according to the invention is constructed from a total of ten scaffold plates. These scaffold plates are arranged in axially uniform spacing over the entire axial length of the rotary piston on the rotary piston hub. Each two adjacent scaffold plates are positioned by three spacer elements 30 to each other, which form a spacer. Instead of assembling the spacer element of three spacer element pieces, it is advantageous for simplifying the assembly in some applications to produce the spacer element in one piece, for example by connecting the three spacer element pieces to one another via webs or the like.

A spacer element piece 30 is shown in FIGS. 8 and 9. As can be seen from these figures, the spacer element piece 30 has a substantially annular body which has a central axial recess 31. On a front side of the spacer element piece 30, a circumferential shoulder 32 is formed. The outer diameter of this shoulder 32 is slightly smaller than the inner diameter of the circular recesses 26, 27, 28 in the scaffolding plates and thereby allows a positive centered positioning of the spacer element piece 30 within these recesses. On the opposite side of the spacer element piece is formed with a flat end face. In principle, as an alternative to this, a corresponding circumferential shoulder can also be designed on the opposite side, which achieves a defined positioning of two adjacent framework plates relative to one another. When using the distance element pieces for a rotary piston with straight rotary lobes, the paragraphs on the two end faces can be coaxial with each other, when using the spacer element piece for a rotary piston with screw shaped course of the rotary wing wings paragraphs are to be carried out with a corresponding eccentric offset from each other.

Each spacer element piece 30 further has in a peripheral portion a rounded recess 33, the radius of which corresponds to the radius of the outer surface of the rotary piston hub. The spacer element piece can thereby be positioned directly resting on the rotary piston hub and secured against rotation.

A rotary piston according to the invention is constructed by a framework which comprises a plurality of scaffold plates 20 and in each case three spacer element pieces 30 between two adjacent scaffold plates. By this construction, a loadable framework structure is provided, which defines the contour of the rotary piston wings and has a positive connection to the rotary piston hub. It is to be understood that the scaffold plates are preferably made of a metallic material. The spacer elements may preferably be made of a polymeric material.

The scaffolding construction thus constructed with the rotary piston hub is subsequently filled with the polymer material and enveloped. This filling and wrapping process can be carried out in particular such that three already cured, for example vulcanized polymer strands are pushed through the openings 26, 27, 28 of the scaffold plates, wherein it is particularly advantageous if an elastically deformable polymer material having an outer diameter which is slightly smaller as the inner diameter of these openings, this is used to follow the helical course in which these openings are staggered to each other to follow. Alternatively, prefabricated vulcanizable polymer strands can also be used in the openings, in which case the vulcanization of the polymer strands takes place during the subsequent vulcanization of the coating or coating with the remaining polymer material.

Following this, the thus prepared framework structure can be overmolded and coated with the already used, prefabricated polymer components with a liquid polymer material, whereby the cavities within the framework structure are completely filled. Due to the high volume fraction of already cured and crosslinked polymer material, a small shrinkage of the polymer material is achieved in the course of its crosslinking. In particular, a staggered, two-stage coating with the liquid polymer material can be carried out in order to achieve in a first encapsulation, a filling up to or slightly below the outer edge of the scaffold plates and in a second encapsulation thereafter the complete outer conformation. to reach the door with wrapping of the scaffolding. In principle, the material thickness depends on the application case and the overall dimension of the rotary piston, for example a material thickness of at least 5 mm of polymer material can be provided between the outer edges of the framework plates and the outer contour of the rotary piston.

Due to its construction, the rotary piston according to the invention has a rigid construction which can be loaded with a high torque. At the same time, the proportion of metallic material is significantly reduced, whereby the weight of the rotary piston and the consumption of valuable starting materials is significantly reduced. The production of the rotary piston is considerably simplified due to the possible modularity with the use of identical components. For example, by using different rotary lobes with different pitches of the webs or lengths made thereon, rotary lobes having different pitches of the lobe wings or different lengths can be made in a modular system.

Claims

claims

Rotary pump, comprising

a housing with a housing interior

an inlet opening through which liquid can flow into the housing interior,

an outlet opening through which liquid can flow out of the housing interior,

a first rotary piston which is rotatably mounted about a first axis of rotation within the housing interior, and

a second rotary piston which is rotatably mounted about a second axis of rotation within the housing interior,

wherein the first rotary piston and the second rotary piston intermesh and displace fluid in a region between the first and second axes,

characterized in that the first rotary piston has a framework arrangement comprising a plurality of spaced-apart plates and that the framework arrangement is at least partially filled with a polymer material and at least partially sheathed.

Rotary pump according to claim 1,

characterized in that

the plates are formed of a material different from the polymer material, preferably made of a metallic material sheets, or

the polymer material is formed of a material other than the plates, preferably a rubber-elastic material.

Rotary pump according to claim 1 or 2,

characterized in that the plurality of spaced apart plates are aligned parallel to each other and / or that the distance between each two spaced apart plates is equal. Rotary pump according to one of the preceding claims,

characterized by spacer elements which hold the plates at a predetermined distance from each other.

Rotary pump according to claim 4,

characterized in that the spacer elements are separate components from the plates and each spacer element has at least two Plattenanschlagsflächen for correspondingly at least two plates, preferably each plate tenanschlagfläche from two, three or more mutually aligned and spaced apart Plattenanschlagflächenteilen is composed.

Rotary pump according to claim 4 or 5,

characterized in that each spacer element at least two Distanzele- mentanschlagflächen for correspondingly has at least two plates, preferably each Distanzelementanschlagfläche of two, three or more mutually aligned and spaced Distanzelementanschlagflä- chenteilen parts is composed and that two adjacent plates on the Distanzelementanschlagsflächen in direct contact to each other.

Rotary pump according to claim 2 and one of claims 4 to 6, characterized in that

the spacer elements are formed from a material different from the polymer material, which in particular has a thermal expansion coefficient which is less than 75%, preferably less than 50%, of the thermal expansion coefficient of the polymer material. the spacer elements are formed from a different material from the plates, and / or

the spacer elements are formed of a polymeric material. Rotary pump according to claim 4,

characterized in that the spacer elements are integrally formed on the plates, in particular each a spacer element is integrally formed on a respective plate, each plate having at least one, preferably three Distanzelementanschlagflächen, at a predetermined height above the plane of the plate lie and at their end facing away from the plane of the plate in contact with another plate, in particular an adjacent plate, wherein the / the spacer element (s) are preferably made by angled deformation of a portion of the plate. 9. Rotary piston pump according to one of the preceding claims,

characterized in that the polymer material by

a prefabricated polymeric member intercalated by mating apertures in the panels and a polymeric material portion formed by flowable polymeric material which at least partially envelops the panels and prefabricated polymeric member in a flowable state and thereafter crosslinks to a solid state,

is formed.

10. Rotary pump according to one of the preceding claims,

characterized in that the mechanical connection between the polymer material and the plates

through adhesive bonding,

by positive engagement between the polymeric material and plate surfaces defining openings or recesses in the plates filled with the polymeric material, and / or

by frictional connection by means of clamping elements, which clamp the plates and the polymer material together,

is formed.

1 1. Rotary pump according to one of the preceding claims,

characterized in that the second rotary piston has a framework arrangement comprising a plurality of spaced-apart plates and that the framework arrangement is at least partially filled with a polymer material and at least partially sheathed.

12. Rotary pump according to one of the preceding claims, characterized in that the first and / or the second rotary piston has an internal, non-circular opening which is formed by an opening in the plates not filled with the polymer material and in that the first and second rotary pistons respectively are connected via a first or second shaft, which is arranged in this opening, is rotatably mounted.

Rotary pump according to one of the preceding claims,

characterized in that the first and the second rotary pistons have at least two rotary-piston vanes which run in a helix along the outer circumference of the rotary pistons and that the plates have a corresponding geometry with at least two rotary-piston vanes, wherein

all plates are geometrically the same and the helical course is effected by means of a non-circular, helically extending outer contour of a drive shaft or hub, which is in positive engagement with a central recess of the plates, or

the plates are subdivided into at least two sets which are slid onto a shaft or hub with a rectilinear, non-circular outer contour, the plates within a set having a matching geometry and the plates of two different sets having a divergent geometry such that the Angular position between the non-circular contour of the central recess and the rotary wing between the plates of two different sets is different from each other.

Method for producing a rotary piston for a rotary lobe pump, comprising the steps of:

Forming a framework arrangement by providing a plurality of spaced apart plates,

At least partial wrapping of the framework arrangement with a

Polymer material in a flowable state, and

Bonding the scaffold assembly to the polymeric material by crosslinking the polymeric material. Method according to claim 14,

characterized in that the framework arrangement is formed by the plates are positioned in parallel and spaced from each other before the at least partially enveloping the polymer material by spacer elements and that the spacer elements are preferably coated with the polymer material and become part of the rotary piston.

Method according to claim 14 or 15,

characterized in that each two plates

by separate from the plates spacers having abutment surfaces for two plates, or

by at least one, two or three spacer elements formed on the plates, which in particular are provided by making the plates from sheet metal and angling at each plate at least one, two or three sections of the sheet, are spaced and preferably positioned parallel to one another.

Method according to one of claims 14 to 16,

characterized in that the polymer material by

Preforming a block polymer component by crosslinking a prefabrication portion of the polymeric material prior to forming the framework assembly

Placing the block polymer component in openings or recesses in the plates,

Arranging the plates and the block polymer component in a cavity of a mold, and

At least partially wrapping the plates and the block polymer component with a flow rate of the polymer material in the state of a flowable polymer material by filling the flowable polymer material into the cavity of the mold, and

Crosslinking the flow rate of the polymeric material to a solid state in the cavity of the mold,

getting produced.

18. The method according to any one of claims 14 to 17,

characterized in that the at least partially wrapping of the plates with the polymeric material is carried out by:

In a first step, a first portion of the flowable polymer material is introduced into a cavity of a casting mold, in which the framework is arranged,

In a subsequent second step, the first portion of the polymer material is crosslinked, and

in a subsequent third step, the framework and the crosslinked first portion of the polymer material with a second portion of the flowable

Polymer material is at least partially enveloped, in particular by the second portion of the flowable polymer material is filled into the cavity of the mold or a cavity of another mold, in which the framework and the crosslinked first portion of the polymer material are arranged.

19. The method according to any one of claims 14 to 18,

characterized in that the plates are wetted with a primer solution prior to at least partially enveloping the plates with the polymeric material, in particular by dipping the plates individually or as a scaffold in a primer solution.

20. Rotary piston for a rotary lobe pump,

characterized by a framework arrangement comprising a plurality of spaced-apart plates, wherein the framework arrangement is at least partially filled with a polymer material and at least partially sheathed.

21. Rotary piston according to claim 20,

characterized in that the rotary piston has one of the features of the rotary piston of claims 2-13, or is made by a method according to any one of claims 14-19.