DE10049730A1 - - Screw extruder-gear pump system for polymer melts and rubber mixtures has screw shaft and pump driven by common drive, planet carrier fitted with planet wheels, annulus surrounding them and seal surrounding planet wheels - Google Patents

Abstract

Screw extruder-gear pump system for high viscosity materials, especially polymer melts and rubber mixtures has the screw shaft (17) and pump (18) driven by a common drive, the pump casing (4) being integral with the screw housing (16). A planet carrier (2) is mounted on the shaft and carries one or more planet wheels (1) which cooperate with an annulus (3) mounted around them. An inlet wall (5) with apertures (6) for flow of plastic separates a suction chamber (9) from a compression chamber (10a) and an outlet wall (7) with outlets (8) is mounted on the other side of the planet carrier. A sealing component (12) attached to the planet carrier surrounds the planet wheels and extends from the inlet to the outlet wall.

Description

The invention relates to a gear pump according to the generic term of Claim 1 and the use of this pump.

From DE-A 21 00 403 a hydraulic pump is known, which is in the form of a Planetary gear with a sun gear, several rotatable on a planet carrier bearing planet gears and a ring gear is equipped, all wheels have a toothing. Between the planet gears and the ring gear, the mesh with each other, as well as between the planet gears and the sun gear combing each other are alternately suction and pressure chamber elements formed by arcuate partitions of the planet carrier, the rest the gaps between the gears are filled, sealed. The flat sides the planet gears, the ring gear and the sun gear are each close to two in Distance from each other arranged flat housing walls with Wall openings are provided, which the individual suction and Pressure chamber elements between the gears with a hydraulic line provided and acting as a collector suction chamber or with one with a Hydraulic drainage provided and also act as a collector pressure chamber connect. In this known gear pump, which is called a planetary gear pump is designated, the planet carrier is preferably fixed, while the sun gear and revolve around the ring gear. Such a pump is for pumping highly viscous media basically unsuitable because it is fed with a substantial form would have to be and would therefore not be self-cleaning.  

A similar gear pump, which is known from DE 36 31 527 C1, allows one speed-independent variation of their delivery rate. The pump in turn points toothed planet wheels, a planet carrier and a toothed ring gear as well a toothed sun gear on the outside enclosed by a pump housing are. To change the flow rate, regardless of the speed of the driven sun gear optionally the orbital movement of the tarpaulin support or the rotation of the ring gear can be stopped. The tarpaulin is with an inlet sealing wall having a plurality of inlet openings and one of them axially spaced outlet sealing wall having a plurality of outlet openings provided that rotatably and sealed in the cylindrical pump housing are. In the pump housing there is an upstream of the inlet sealing wall Suction chamber and a pressure chamber behind the inlet sealing wall in the conveying direction arranged. The suction chamber extends through the inlet openings in individual suction chamber elements, which extend to the exit sealing wall, during the Pressure chamber extends through the outlet openings into individual pressure chamber elements, that extend to the entrance sealing wall. The suction chamber elements and the Pressure chamber elements are in the spaces between a planet gear, the ring gear and the sun gear are arranged and are sealed against each other through the entrance and exit sealing wall as well as through space filling Parts of the solid between the entrance and the exit sealing wall executed planet carrier. The supply line for the medium to be pumped runs in Form of a longitudinal bore, which merges into a transverse bore, within the through the Wall of the pump housing guided axis of rotation of the planet carrier, while the Derivation for the pumped medium in a corresponding manner through the axis of rotation the sun gear is guided. Because of the small diameter of the holes and the Small cross-sectional areas of the inlet and outlet openings would be one Pump is unsuitable for conveying highly viscous media and would not be self-cleaning.

Another gear pump working as a planetary gear pump is known from US Pat. No. 3,870,437 known. The volume to be pumped is in each case in the space between the sun gear and the ring gear and two immediately adjacent Planet wheels included. To create the size of this space the pumping action during the rotation of the planet gears in the range of Intake point (inflow area) to enlarge continuously and in the area of  This pump has the flexibility to continuously reduce the pressure zone (outflow area) deformable gears on, for example, the ring gear and the driven Sun gear arranged eccentrically to one another and flexible planet gears used be the different gap width between the ring gear and sun gear can adapt by deformation (ovality).

Common feature of these known planetary gear pumps is that not only the planet gears but also the ring gear and the sun gear each Have gears that together in the sense of a planetary gear intermeshing intervention.

So far, when processing plastic melts or rubber mixtures Gear pumps in use, which work in the sense of a spur gear and are usually connected to a screw extruder Gear pump is separate from the drive of the extruder shaft or shafts Drive on. Such an extruder is known for example from EP 0 508 080 A2. An extruder screw conveys the material to be extruded directly into the Gusset area of the gear pump, the two meshing spur gears having. This type of gear pump is not self-cleaning and therefore requires Mostly complex when changing the material to be processed Disassembly and cleaning work to avoid any loss of quality after a To have to accept material changes.

A twin screw extruder is known from EP 0 564 884 A1 Worm shafts in a section to increase the pressure of the processed Melt are each equipped with one of the two spur gears of a gear pump, so that the gears are driven directly by the worm shafts. By two front, d. H. perpendicular to the longitudinal axis of the worm shafts Sealing walls with a passage window for the melt to the entry side or are provided on the outlet side, the suction chamber and the pressure chamber are separated from each other Cut. This gear pump is also not self-cleaning. Your funding volume can cannot be changed independently of the speed of the worm shafts.

Finally, a single-screw extruder is known from EP 0 642 913 A1, which pre- its last screw section a gear pump of the type one  Helical gear has. One of the two spur gears of the gear pump is directly attached to the screw shaft of the screw extruder and is by this driven. The extruder housing has a lateral bulge in which the second spur gear of the gear pump is mounted. On the flat sides of the spur gears there is a sealing wall, which is positively mounted in the housing of the extruder is. The sealing walls or the extruder housing are each with a suction side or pressure-side passage window for the material to be extruded. Also No self-cleaning is guaranteed with this known extruder.

The object of the invention is to propose a gear pump, which in particular Way is suitable for processing highly viscous materials and largely works self-cleaning. Furthermore, an advantageous use of this Gear pump can be specified.

This task is solved with a generic gear pump with the characterizing part of claim 1 specified features. advantageous Developments of this gear pump result from the dependent Dependent claims. An advantageous use of a gear pump results from independent claim 16 and the dependent claims dependent thereon.

The present invention provides a gear pump, in principle is constructed according to a planetary gear and in a special way Promotion of highly viscous media such as plastic melts and rubber mixtures is suitable and has the advantage of extensive self-cleaning, since the The medium to be pumped can be fed in without any appreciable form. The invention relates to a planetary gear pump that has a planet carrier having at least one rotatably mounted in the planet carrier Planet gear is equipped. This planetary gear pump also has two more Functional elements on the at least one planet gear in the sense of a Interact sun gear or a ring gear. They are also a Pump housing that the planet carrier with the planet gears and the two surrounds the aforementioned functional elements from the outside, and an input and a Exit sealing wall provided. The entrance sealing wall is with the planet carrier non-rotatably connected and has at least one inlet opening for the material to be conveyed Medium on. In a corresponding manner, the exit sealing wall with the  Planet carrier rotatably connected and with at least one outlet opening for the Provide the medium to be funded. In addition, this gear pump has one Suction chamber and a pressure chamber, which are enclosed by the pump housing and are sealed against each other, the suction chamber in the conveying direction in front of the Entry sealing wall is arranged and through the at least one inlet opening into at least one suction space element along the at least one Planetary gear extends to the outlet sealing wall and the pressure space in Delivery direction is arranged behind the exit sealing wall and through the at least one outlet opening into at least one pressure chamber element extends along the at least one planet gear up to the input sealing wall. According to the invention, it is provided in such a gear pump that in each case only one of the two functional elements acting as a sun gear or a ring gear has meshing teeth with the at least one planet gear, whereas the other functional element has at least one sealing area that is smooth-walled and is designed so that it extends over part of the circumference and over the length of the at least one planet gear slidably bears against it. Furthermore, the Invention before that the functional element, which the at least one Has sealing area, is rotatably connected to the planet carrier, so the same Movements. A sealed separation of the at least one Ensure suction chamber element of the at least one pressure element the invention as a further essential feature that offset in the circumferential direction to the at least one planet gear at least one of the Entry sealing wall arranged up to the exit sealing wall extending partition is that with the functional element, which the at least one smooth-walled Has sealing area, is rotatably and sealingly connected and in a radial Direction up to the tip circle of the toothing of the toothing Functional elements extends.

The functional element, which is similar to the at least one Planet gear is toothed and meshes with it, is preferably the ring gear. There this can be arranged fixed, it is expediently in one piece with the pump housing or at least rotatably in which the ring gear surrounding pump housing. In this case, the planet carrier runs with it around the functional part corresponding to the sun gear and is preferably in one piece executed with this. A toothed sun gear, like a normal one  There is no planetary gear here. That at least one planet gear does not mesh with a toothing of such a sun gear, but moves slidably sealed in at least one sealing area of the otherwise than Functional part of the sun gear.

Of course, it is also possible to choose a reverse arrangement in which a toothed sun gear is used while the one that functions as a ring gear Functional part has no teeth, but with the at least one Sealing area is provided. In this case, the "ring gear" can be like the planet carrier stand still. Because of the simpler construction, the aforementioned solution is also included toothed ring gear and preferred with toothless "sun gear".

Expediently, several planet gears, partitions, entry and Outlet openings are provided, i.e. at least two, preferably each at least four. The teeth of the planet gears and the meshing with them Functional part (preferably the ring gear) can be straight-toothed, but will preferably designed with helical teeth. This enables a special Even promotion of the planetary gear pump according to the invention.

The planet gears and the meshing functional part can also be serrated be executed. In this case, however, disassembly is made more difficult. By a shared Execution z. B. the ring gear can be difficult even under these Conditions still a disassembly.

In a further expedient embodiment, the invention provides that the Partitions in the axial direction in a similar way as the helical teeth run helically. It is recommended that the partitions are made in one piece with the the functional element having at least one sealing area, that is preferably in one piece with the "sun gear". Even the planet carrier is expediently formed in one piece with the "sun gear" in this case.

The planet gears are expedient in the entrance sealing wall and the Output sealing wall mounted so that they are part of the planet carrier. Of course, a separate design of these components is also possible. In order to the planet gears can be easily assembled and disassembled, it is advantageous  only one of the two sealing walls, preferably the entrance sealing wall, in one piece form with the planet carrier and the other sealing wall as a separate component to leave.

To easily the gear pump according to the invention in a housing To be able to accommodate screw extruders and easy disassembly ensure, it is recommended the outside diameter of the entrance sealing wall unequal, d. H. preferably to be made smaller than the outer diameter of the Starting off wall. This allows the gear pump, which is mostly on Conveying end of a screw extruder is easily connected to this Pull the head end of the extruder out of the housing.

To change the delivery volume of the gear pump during operation To enable a further preferred embodiment of the invention, the Planet carrier together with the functional part corresponding to the sun gear the inlet and the outlet sealing wall within the pump housing axially Compatible with the toothed ring gear by a displacement w to arrange. This allows the length of the meshing between the ring gear and the planet gears and thus the displacement volume of the teeth can be varied. So that no undesired leaks between the suction chamber and the Pressure chamber arise, it is recommended that the sealed in the pump housing slidable stored entrance sealing wall, which moves when moving into the gear area of the ring gear moves in their axial thickness d (i.e. in the direction of displacement seen) to be chosen larger than the maximum displacement w. This leaves the Seal between the pump housing and the inlet sealing wall unchanged receive. However, a deliberate leak can also be provided between pressure chamber and suction chamber by a slight shift set in order to reduce the delivery rate of the pump.

The throttling of the delivery rate during operation is different known planetary gear pumps without a constantly required second drive for one of the functional elements (ring gear or sun gear) possible because only for the a short time of axial adjustment of the gear pump a drive with a so far extremely low energy consumption is required. Due to the adjustability of the  Delivery rate of the gear pump is an adaptation to the processing different materials possible.

From a manufacturing point of view it can be recommended to use the planet gears and / or the meshing ring gear or sun gear in the area near the surface the gearing to be soft and elastic. In this case, the exact interlocking of metallic roughly tolerated manufacturing Gear body are manufactured, the smaller dimensions than that Have target dimensions of the finished gearing and then with a elastic covering, in particular a covering made of rubber or a thermoplastic elastomer. Because this wrapping is excellent Has elastic properties are also the requirements for in this way completed toothing less than with a purely metallic toothing. Oversize can be compensated for by deformation. By a The tooth cavities of the ring gear can be rubber coated with a slight oversize be completely cleaned out.

In a further variant, the invention provides for the toothing of the ring gear or the planet gears alternately or in sections with teeth different Execute height, so for example to use a planet gear in which the Half of the teeth are a normal size and the other half of the teeth are reduced Has size, with the two tooth sizes constantly changing over the circumference alternate. If the pump has several planet gears, you can different planet gears are used, d. H. Planet wheels with normal Tooth height and other planet gears with reduced tooth height. The one that can be achieved with it The effect can be seen in the fact that due to the partially reduced tooth height a Compacting of the material can take place, which in the tooth gaps with the respective gear cooperating counter gear is included. The compact Material would then only come out when it meets a fully developed tooth the tooth gap are expressed and promoted.

In the case of a planet gear with a continuously reduced tooth height, this will result in Tooth gaps of the ring gear material is first compressed and only by a subsequent planet gear, the teeth of which are fully developed, under stretching and Shear flows are pushed out of the tooth gap. With a gear pump  with four planet gears, two opposite one with a reduced one Tooth height and the two other opposing planet gears normal tooth height. The ones present in the gear pump Forced flows favor continuous homogenization and mixing (e.g. fillers) of the material to be processed.

The tooth geometry of the toothing of planet gears and ring gear is in principle any. It only has to be ensured that the teeth of one gear engage the tooth gap of the other gear in such a way that a sealing one Sliding contact with the two the respective tooth gap of the other gear limiting teeth.

According to the invention, one or more gear pumps are of the type one Planetary gear, in particular gear pumps according to one of the claims 1 to 15, in a screw extruder to convey flowable media such as especially plastic melts and rubber mixtures used, the Screw extruder can have one or more screw shafts and the Auger shaft or shafts each mechanically with the drive of the gear pump are coupled so that no separate pump drive is required. So is also no separate control required to drive the gear pump.

Usually the pump housing is attached directly to the housing of the Screw extruder connected or is preferably part of the Extruder barrel.

The number of gears of the worm shaft or shafts is particularly advantageous Conveying end equal to the number of planet gears connected to it Gear pump selected. The number of gears does not have to be over the entire range Screw length must be constant. A preferred use of the Gear pumps according to the invention provide for the number of turns of the worm shafts the section of the screw shafts lying in front of the end of the conveyor is half as much big as to choose at the end of funding.

When using a planetary gear pump with helical teeth, it is advantageous to Inclination of the spiral of the worm shaft gears in relation to the  Direction of conveyance of the screw extruder in each case in the opposite direction to be provided as the inclination of the toothing.

To the delivery rate of the screw extruder with the planetary pump without To be able to influence changes in the drive speed, it is recommended that Worm shaft together with the planet carrier as well as the sun gear and to arrange the entrance and exit sealing wall axially displaceable. By axial Moving the worm shaft, which is mechanically rotatable with the planet carrier coupled, the delivery rate of the gear pump can be influenced, because in the displacement described above and / or the desired Leakage between the suction chamber and pressure chamber can be controlled.

A major advantage when combining a screw extruder with the Gear pump according to the invention can be seen in that because of the good Pressure build-up properties with simultaneous non-need of a noteworthy Delivery pressure for feeding into the gear pump the extruder screw in front of the Gear pump can be run very short. The length is preferably the extruder screw two to five times the value of the screw diameter.

A particularly advantageous use of the planetary gear pump results in one Screw extruder in particular for processing rubber mixtures, if behind the gear pump is a pin cylinder extruder area, such as the one from DE 40 39 942 A1, the disclosure content of which in this respect Registration is involved, is known. The planetary gear pump can be used for easily build up the advantageous high pre-pressure in the pin cylinder extruder area.

In a further advantageous use it is provided that behind such Pin cylinder extruder area a vacuum degassing area is connected, which is followed by a second planetary gear pump at the end of the extruder, around which to deliver the required extrusion pressure at the extruder outlet.

The invention is described below with reference to the figures Exemplary embodiments explained in more detail. The figures show in a schematic Presentation:  

Fig. 1 shows a longitudinal section through a single screw extruder with planet gear pump,

Fig. 2 shows the longitudinal section according to Fig. 1 in the form of a winding,

Fig. 3a-d cross-sections according to the line AA, BB, CC and DD in Fig. 1,

Fig. 4 shows a modification of the screw extruder of FIG. 1 by the axial displaceability of the worm shaft,

Fig. 5 shows a screw extruder with planet gear pump connected thereto, and pin barrel extruder region,

Fig. 6 is a screw extruder having two series-connected Planetenradpumpen, pin barrel extruder region and Vakuumentgasungsbereich,

Fig. 7 is a sectional view of a planet gear with a flexible cover and

Fig. 8 is a planetary gear with alternately different teeth.

In Figs. 1 to 3D is a screw extruder 15 in an axial longitudinal section, a plurality of transverse cuts and a schematic development (Fig. 2). The screw extruder 15 has a screw shaft 17 which , when viewed in the direction of conveyance, is initially designed with two courses and at the end of the conveyor 19 has twice the number of flights, that is to say four courses. The screw shaft 17 is surrounded by an extruder housing 16 . Directly connected to the delivery end 19 is a planet gear pump 18 , which has an essentially cylindrical pump housing 4 , within which a planet carrier 2 with four rotatably mounted planet gears 1 is arranged. In the area of the wall of the pump housing 4 , a toothed ring gear 3 is provided on the inside, which in a preferred embodiment of the invention is made in one piece with this part of the pump housing 4 . On the left side of the planet gears 1 there is an input sealing wall 5 which is sealed and rotatably mounted in the extruder housing 16 . This input sealing wall 5 is provided with four inlet openings 6 in accordance with the number of planet gears 1 ( FIG. 3a). On the right side of the planet gears 1 there is an outlet sealing wall 7 , which is provided in a corresponding manner with four outlet openings 8 ( FIG. 3d). The outlet sealing wall 7 is also rotatably mounted, specifically in the pump housing 4 . The suction chamber 9 of the gear pump 18 is located to the left of the inlet sealing wall 5 , that is to say at the end of the 4-course part of the worm shaft 17 , while its pressure chamber 10 is located on the right side of the outlet sealing wall 7 . The suction chamber 9 extends through the inlet openings 6 in the form of suction chamber elements 9 a along a respective planet wheel 1 to the outlet sealing wall 7 . In a corresponding way, in each case one planetary gear 1, the pressure chamber 10 of a respective pressure chamber element 10 a (3b 3c Fig. 1,) extends on the diametrically opposite side in the form through the exit apertures 6 through to the input sealing wall 5. The planet carrier 2 , to which the input sealing wall 5 and the output sealing wall 7 also functionally belong, since these accommodate the mounting of the planet gears 1 , is provided with a total of four partition walls 12 , which are essentially radial from a central base body between the planet gears 1 to Extend toothing of the ring gear 3 . The tip circle of the toothing of the ring gear 3 is shown in dashed lines in FIGS . 3b, c, as is the tip circle of the toothing of the planet gears 1 . From Fig. 3b, c can also be seen that the planet gears 1 are each slidably sealingly abut against the respective associated partition walls 12 and the central basic body of the planet carrier 2 in a smooth cylindrical-shaped sealing area 11. The sealing walls 12 are made in one piece with the planet carrier 2 . The planet gears 1 are in engagement with the toothing of the ring gear 3 , so that there is also a sealed engagement. Seen in cross section, the suction chamber elements 9 a are each closed by a partition 12 , the central base body of the planet carrier 2 , an associated planet gear 1 , which lies sealingly against the central base body and in the toothing of the ring gear 3 , and by a part of the ring gear 3 , The same applies correspondingly to the pressure chamber elements 10 a, which are diametrically opposite each other with respect to the axis of the planet gears 1 and which in the illustrated cutting position of FIG. 3 b in the vicinity of the inlet sealing wall 5 have only a very small cross section. The reverse size relationships result from a corresponding cut near the exit sealing wall 7 . There, the suction chamber elements 9 a would have the size of the pressure chamber elements 10 a in FIG. 3 b. Accordingly, the cross section of the pressure chamber element 10 a would each have the size of the suction chamber element 9 a in FIG. 3 b. This means that the suction chamber elements 9 a continuously reduce in cross section from the inlet opening 6 to the outlet sealing wall 7 , while the opposite pressure chamber elements 10 a continuously enlarge in cross section from the inlet sealing wall 5 to the outlet openings 8 in the outlet sealing wall 7 . In the center between the input sealing wall 5 and the output of the sealing wall 7 Saugraumelemente 9 a, as shown in Fig. 3c shows a cross section about equal to the pressure chamber members 10 a. While the central body of the planet carrier 2 , which corresponds to the sun gear in a conventional planetary gear, has no teeth, the ring gear 3 , like the planet gears 1, is advantageously equipped with helical teeth. Also in a preferred development of the invention, the partitions 12 are helical, ie inclined with respect to the longitudinal axis of the screw extruder 15 , the inclination of this incline pointing in the opposite direction to the inclination of the flights of the screw shaft 17 ( FIG. 1). The exit from the extruder shown is designated by reference numeral 22 .

It can be seen from the sectional view in FIG. 1 that the pump housing 4 has an enlarged diameter compared to the extruder housing 16 . The extruder housing 16 has an inner diameter which is slightly smaller than the diameter of the tip circle of the toothing of the ring gear 3 , so that the right end wall of the extruder housing 16 in the vicinity of the section line BB shown completely covers the cross-sectional areas of the tooth spaces of the toothing of the ring gear 3 . The same applies to the tooth gaps of the planet gears 1 , insofar as they are in the area of engagement with the toothing of the ring gear 3 . Otherwise, the planet gears 1 and the entire space apart from the necessary entry openings 6 are completely closed by the inlet sealing wall 5 ( FIG. 3a). The same applies on the other side of the planet gears 1 in relation to the outlet sealing wall 7 and the outlet openings 8 ( FIG. 3d). The outlet sealing wall 7 has an outer diameter which corresponds to the inside diameter of the pump housing 4 , so that the tooth gaps of the toothing of the ring gear 3 on the right end face of the toothing are completely sealed by the outlet sealing wall 7 . Since the outer diameter of the input sealing wall 5 is deliberately chosen to be smaller than the tip diameter of the toothing of the ring gear 3 , the entire unit of the planet carrier 2 with the planet gears 1 and the two sealing walls 5 , 7 can be easily removed from the right for the purpose of disassembly after removal of a head piece 25 Pump housing 4 are pulled out.

The screw extruder shown works as follows: The medium to be processed, for example the melt of a thermoplastic, is conveyed by the screw shaft 17 from left to right in the direction of the gear pump 18 . From the initially two partial flows, which move along the 2-speed worm shaft, four partial flows are generated at the end of the conveyor 19 by the two additional worm threads. The screw flights each end, as can be seen particularly clearly from the development of FIG. 2, at an inlet opening 6 , that is to say they open into a suction chamber element 9 a. Since the worm shaft 17 is mechanically coupled to the planet carrier 2 , the latter carries out the same rotary movements together with the sealing walls 5 , 7 which are also coupled to it. The melt passes through the comparatively large inlet openings 6 into the individual saunas 9 a, without this requiring a substantial pre-pressure. Through the partitions 12 , the material of the melt is brushed into the tooth gaps of the toothing of the ring gear 3 in accordance with the direction of rotation shown. The melt is conveyed into the opposite pressure chamber element 10 a on each planet gear 1 in two partial flows. The one partial flow is guided in the tooth gaps of the respective planet gear 1 along the sealing zones 11 into the associated pressure chamber element 10 a, while a second mass flow is generated by squeezing the melt out of the tooth gaps of the ring gear 3 as a result of the engagement of the toothing of the planet gears 1 . In this way, the total flow still consisting of four partial flows at the pump inlet is now divided into a total of eight partial flows, so that the planetary gear pump can contribute to an improvement in the material mixture. Characterized in that the inside is coated material to be conveyed during the rotation of the Plant carrier 2 of the radial partitions 12 in the tooth gaps of the ring gear 3, also results in a particular suitability of this gear pump to substantially self-cleaning.

The inlet sealing wall 5 and thus at least a part of the planet carrier 2 can also be a physical part of the worm shaft 17 , so they do not have to be separate components.

FIG. 4 shows a modification of the screw extruder with planetary gear pump shown in FIGS. 1 to 3d. The basic construction and function of this screw extruder corresponds to the latter, so that reference is made to the above description in this regard. In contrast to this, however, the screw shaft 17 of the screw extruder 15 in FIG. 4, together with the planet carrier 2 and the associated input sealing wall 5 and output sealing wall 7, can be displaced in the axial direction, as is indicated by the double arrow shown thick on the longitudinal axis of the extruder. The toothing width of the ring gear 3 is denoted by b ₁ and the toothing width of the planet gears 1 by b ₂ . Both tooth widths b ₁ , b ₂ are approximately the same size, so that in a starting position, not shown, in which the worm shaft with the planet carrier 3 mechanically coupled to it to the left. is shifted (left end position), both toothing widths b ₁ , b ₂ completely overlap. The displacement path of the worm shaft 17 and the planet carrier 2 that has occurred in relation to this starting position is denoted by w in FIG. 4. Thus, in the position shown (in the vicinity of the right end position), the toothing engages only over a length b ₁ -w. The delivery volume of the gear pump 18 is reduced accordingly. In this case, the partial flow of the conveyed quantity which is conducted past the sealing regions 11 (FIGS . 3b, c) remains completely unaffected. Only the partial flow changes, which is caused by the displacement of the teeth of the planet gears 1 engaging in the tooth gaps of the ring gear 3 . In order to prevent an undesired leakage between the pressure chamber 10 and the suction chamber 9 in the region of the tooth spaces on the left side of the ring gear 3 from occurring due to the axial displacement of the planet carrier 3 of the gear pump 18 , the thickness of the inlet sealing wall 5 is denoted by d is considerably larger than the thickness of the outlet sealing wall 7 . In order to maintain the tightness, this thickness d must be at least slightly greater than the maximum displacement path w, so that the circumference of the inlet sealing wall 5 continues to lie tightly against the smooth-walled inside of the extruder housing 16 or a pump housing 4 which is continued in this area. If this overlap of the inlet sealing wall 5 with the extruder housing 16 were not present, a backflow would arise from the pressure chamber 10 through those tooth gaps of the ring gear 3 which are not currently in engagement with the corresponding teeth of the planet gears 2 . This effect of the backflow could also be generated and controlled consciously in order to regulate the delivery rate of the pump. In this respect, the considerable increase in the thickness of the inlet sealing wall 5 is not absolutely necessary in order to maintain the functionality of the gear pump 18 despite the displacement of the planet carrier 3 in the axial direction. In this way, the delivery rate of the gear pump 18 can be reduced even more than is possible in the embodiment shown in FIG. 4.

Fig. 5 shows a similar arrangement of screw extruder 15 with gear pump 18 , which is only supplemented by the feature that in the conveying direction, which goes from left to right, behind the gear pump 18 a pin cylinder extruder area 20 is connected, as it is particularly for processing of rubber compounds is often used. Pins 23 are inserted into the housing of the pin cylinder extruder area 20 and, as indicated by the double arrows, can be placed in the radial direction on the longitudinal axis of the extruder. In this case, the gear pump 18 ensures that there is still sufficient pressure at the end of the pin cylinder extruder region 20 for the extrusion of the processed material.

In FIG. 6 the arrangement according to FIG. 5 has been expanded by two further sections. To the pin barrel extruder region 20 is adjoined in the conveying direction, namely first a Vakuumentgasungsbereich 21 with a vacuum port 24 and an input-side blister 26, and while still a second gear pump 18 is connected with a 4-flighted screw shaft 17 to the extrusion end, that is at the right end of the arrangement, which generates the desired delivery pressure of the processed melt for extrusion. In this arrangement, decoupling of the build-up length and extrusion pressure is made possible by volumetric conveying by the two gear pumps 18 , so that flooding of the vacuum suction in the vacuum degassing area 21 can be avoided.

For the toothing of the ring gear 3 (or, in the case of an inverted pump arrangement, the toothing of the sun gear) and / or the toothing of the planet gears 1 , an embodiment can be selected as is exemplarily and schematically shown in FIG. 7 as a partial sectional view of a planet gear 1 . This planet gear 1 has a gear body 13 , which is preferably made of metal (e.g. steel) and can be tolerated relatively roughly in terms of production technology with regard to the teeth. The individual teeth are significantly smaller and the tooth gaps are significantly larger than is aimed for for the final shape of the planet gear 1 . This final shape is produced by a covering made of a soft elastic material 14 (e.g. rubber or a thermoplastic elastomer). Because of the good deformability of this material, the shape accuracy of the finished planet gear 1 does not have to be as high as it would have to be the case with a rigid material, since excessive tooth geometry can be compensated for by deformation during tooth engagement. Because of the lower demands on the shape accuracy, the manufacturing effort for the gearing can be reduced accordingly. On the other hand, however, particularly high demands on the tightness of the toothing in engagement with respect to an unwanted material backflow can also be met in this way.

A further variation with regard to the toothing that can be used is again indicated schematically in FIG. 8 using the example of a planet gear 1 , which is shown as a detail. This planet gear 1 alternately has teeth of different heights. The difference in tooth height is called Δh. Every second tooth has a lower tooth height than the normal tooth height. Alternatively, several teeth in succession could each have the same height, so that the tooth height would change in regions over the circumference. Planetary gears 1 could also be used which each have the same tooth height but different tooth heights among themselves. A special effect could thus be achieved, namely a compacting of the material located in a tooth gap of the ring gear 3 , which is acted upon by a tooth with a reduced tooth height and thereby at most partially conveyed out of the tooth gap into the pressure chamber 10 . This compacted material could then be conveyed into the pressure chamber by another tooth with normal tooth height penetrating into such a tooth gap during the further rotation of the planet carrier.

The construction of a gear pump proposed according to the invention ensures that when an extruder equipped with such a gear pump runs empty practically all of the melt material from the extruder and with it connected gear pump is promoted because to ensure the Material feed into the gear pump practically no form is required. On in this way, complex cleaning work can be carried out in most cases Avoid changing the material to be processed. Added to that is because of the division of the material flows on each planet gear into two smaller partial flows  this gear pump has a significantly better mixing effect on that too processing material has, as in a usual as a melt pump Gear pump used in the design of a spur gear is the case. There only two partial material flows are generated and brought together again. Both Gear pumps shown in the figures, each with four planet gears are equipped, eight partial flows are generated in the melt flow and again merged. This will result in a significantly better mix of materials guaranteed. Through a simple mechanical coupling of the planet carrier with the The worm shaft of an extruder can be driven by a separate motor Gear pump can be completely dispensed with. Nevertheless, is a regulation of Delivery of the gear pump possible if this is on an axial adjustment is set up as described above.  

LIST OF REFERENCE NUMBERS

1

planet

2

planet carrier

3

ring gear

4

pump housing

5

Entrance off wall

6

inlet opening

7

Starting off wall

8th

outlet opening

9

suction

9

a suction chamber element

10

pressure chamber

10

a pressure chamber element

11

sealing area

12

partition wall

13

Gear body

14

soft elastic covering

15

Screw extruder

16

extruder barrel

17

worm shaft

18

gear pump

19

delivery end

20

Pin cylinder extruder region

21

Vakuumentgasungsbereich

22

extruder outlet

23

Adjustable pen

24

vacuum port

25

headpiece

26

Blister
b ₁

Tooth width ring gear
b ₂

Tooth width planet gear
w displacement
d Thick entrance wall
Δh difference in tooth height

Claims (23)

1. gear pump for conveying highly viscous media, in particular plastic melts and rubber mixtures, in the design of a planetary gear,
with a planet carrier ( 2 ) fitted with at least one rotatably mounted planet gear ( 1 ),
with two other functional elements; which interact with the at least one planet gear ( 1 ) in the sense of a sun gear or a ring gear ( 3 ),
with a planet carrier (2) surrounding the pump housing (4),
with an inlet sealing wall ( 5 ) which is connected in a rotationally fixed manner to the planet carrier ( 2 ) and has at least one inlet opening ( 6 ) for the medium to be conveyed,
with an outlet sealing wall ( 7 ) which is connected to the planet carrier ( 2 ) in a rotationally fixed manner and has at least one outlet opening ( 8 ) for the medium to be conveyed and
and with a suction chamber ( 9 ) and a pressure chamber ( 10 ), which are enclosed by the pump housing ( 4 ) and sealed against one another, the suction chamber ( 9 ) being arranged in the conveying direction in front of the inlet sealing wall ( 5 ) and passing through the at least one inlet opening ( 6 ) extends into at least one suction chamber element ( 9 a) along the at least one planet gear ( 1 ) up to the outlet sealing wall ( 7 ) and the pressure chamber ( 10 ) is arranged in the conveying direction behind the outlet sealing wall ( 7 ) and extends through the at least an outlet opening ( 8 ) extends into at least one pressure chamber element ( 10 ) along the at least one planet gear ( 1 ) up to the inlet sealing wall ( 5 ), characterized in that
that in each case only one of the two functional elements acting as a sun gear or ring gear ( 3 ) has teeth meshing with the at least one planet gear ( 1 ) and the other functional element has at least one sealing area ( 11 ) which is smooth-walled and over part of the circumference and over the The length of the at least one planet gear ( 1 ) is designed to be slidably sealed,
that the other functional element having the at least one sealing area ( 11 ) is connected in a rotationally fixed manner to the planet carrier ( 2 ) and
that at least one Saugraumelements (9) arranged for separation of the of the at least one pressure chamber element (10) offset in the peripheral direction to the at least one planet gear (1) at least one extending from the input sealing wall (5) to the exit sealing wall (7) partition (12) which is connected in a rotationally fixed and sealing manner to the other functional element having the at least one smooth-walled sealing region ( 11 ) and extends in the radial direction up to the tip circle of the toothing of the functional element having the toothing. 2. Gear pump according to claim 1, characterized in that at least two, in particular at least four planet gears ( 1 ), partitions ( 12 ), inlet ( 6 ) and outlet openings ( 8 ) are provided. 3. Gear pump according to claim 1 or 2, characterized in that the toothing of the at least one planet gear ( 1 ) and the toothed functional element is designed as helical teeth. 4. Gear pump according to claim 3, characterized in that the at least one partition ( 12 ) is helical in accordance with the helical teeth in the axial direction. 5. Gear pump according to one of claims 1 to 4, characterized in that the at least one partition ( 12 ) is integrally formed with the functional element having the at least one sealing area ( 11 ). 6. Gear pump according to one of claims 1 to 5, characterized in that the ring gear ( 3 ) with the toothing and the functional part corresponding to the sun gear is provided with the at least one sealing area ( 11 ). 7. Gear pump according to claim 6, characterized in that the planet carrier ( 2 ) and the functional part corresponding to the sun gear are integrally formed. 8. Gear pump according to claim 6 or 7, characterized in that the input sealing wall ( 5 ) or the output sealing wall ( 7 ) is integrally formed with the planet carrier ( 2 ). 9. Gear pump according to one of claims 6 to 8, characterized in that the ring gear ( 3 ) is integrally formed with the part of the pump housing ( 4 ) surrounding the ring gear ( 3 ). 10. Gear pump according to one of claims 6 to 9, characterized in that the outer diameter of the inlet sealing wall ( 5 ) is unequal, in particular smaller than the outer diameter of the outlet sealing wall ( 7 ). 11. Gear pump according to one of claims 6 to 10, characterized in that for changing the delivery volume of the gear pump ( 18 ) of the planet carrier ( 2 ) together with the functional part corresponding to the sun gear and the input ( 5 ) and the output sealing wall ( 7 ) within of the pump housing ( 4 ) is arranged to be axially displaceable relative to the ring gear ( 3 ) by a displacement path w. 12. Gear pump according to claim 11, characterized in that the thickness d (seen in the direction of displacement) of the input sealing wall ( 5 ) is greater than the maximum displacement path w. 13. Gear pump according to one of claims 1 to 12, characterized in that the at least one planetary gear ( 1 ) and / or the functional part having the meshing with the at least one planetary gear ( 1 ) has a soft-elastic design at least in the region near the surface of its toothing /are. 14. Gear pump according to claim 13, characterized in that the toothing is in each case formed by a roughly tolerated metallic gear base body ( 13 ) with an elastic covering ( 14 ), in particular a covering made of rubber or a thermoplastic elastomer, in the toothing area. 15. Gear pump according to one of claims 1 to 14, characterized in that the toothing of the ring gear ( 3 ) or the at least one planet gear ( 1 ) is alternately or in sections with teeth of different heights or in the case of several planet gears ( 1 ) the teeth at least one of these planet gears ( 1 ) has a different tooth height than another planet gear. 16. Use of one or more gear pumps in the form of a planetary gear, in particular according to one of claims 1 to 15, in a screw extruder ( 15 ) for conveying flowable media, in particular plastic melts or rubber mixtures, with one or more screw shafts ( 17 ), the Drive of the gear pump or pumps ( 18 ) is mechanically coupled to the worm shaft (s) ( 15 ). 17. Use according to claim 16, characterized in that the pump housing ( 4 ) is part of the housing ( 18 ) of the screw extruder ( 15 ) or is connected directly thereto. 18. Use according to one of claims 16 to 17, characterized in that the number of gears at the delivery end ( 19 ) of the worm shaft / shafts ( 17 ) is in each case equal to the number of planet gears ( 1 ) of the gear pump ( 18 ) connected to it. 19. Use according to claim 18, characterized in that the number of gears of the section of the worm shaft ( 17 ) lying in front of the conveying end ( 19 ) is half as large as the number of gears at the conveying end ( 19 ). 20. Use according to one of claims 16 to 19, characterized in that the toothing in the gear pump ( 18 ) has helical teeth and the inclination of the winding of the gears of the screw shaft ( 17 ) - in relation to the conveying direction of the screw extruder ( 15 ) - in each case opposite is. 21. Use according to one of claims 16 to 20, characterized in that the worm shaft ( 17 ) together with the planet carrier ( 2 ) and the functional part corresponding to the ring gear as well as the input and output sealing wall ( 5 , 7 ) is arranged axially displaceably , 22. Use according to one of claims 16 to 21, characterized in that a pin cylinder extruder region ( 20 ) is arranged in the conveying direction behind the gear pump ( 18 ). 23. Use according to claim 22, characterized in that two gear pumps ( 18 ) are arranged axially one behind the other on a worm shaft ( 17 ), the second gear pump ( 18 ) in the conveying direction being arranged immediately after a vacuum degassing region ( 21 ) which is connected to the Pin cylinder extruder area ( 20 ) connects.