EP3092410B1 - Progressive cavity pump, pin joint, and method for producing a pin joint - Google Patents

Description

The present invention relates to an eccentric screw pump, a pin joint and method for producing a pin joint according to the features of the preambles of claims 1, 5 and 6.

State of the art

The invention relates to a bolt of a pin joint for progressing cavity pumps. Eccentric screw pumps are pumps for pumping a large number of media, in particular viscous, highly viscous and abrasive media such as sludges, liquid manure, crude oil and fats. Here, the driven, coiled rotor rolls in the stator. This is a housing with a spiral-shaped inside. The rotor performs with its figure axis an eccentric rotation about the stator. The outer screw, i. the stator has the form of a double thread, while the rotor screw is only catchy. The rotor is usually made of a highly abrasion-resistant material, such as steel. The stator, however, consists of an elastic material, for example rubber. Due to the special shape of rotor and stator between the rotor and stator sealed cavities, which move axially upon rotation of the rotor and promote the medium. The volume of the cavities is constant, so that the fluid is not crushed. With a suitable design, not only fluids but also solids can be conveyed with progressing cavity pumps.

From the DE 10 2006 058 166 A1 goes out a pin joint for an eccentric screw pump. The pin joint is surrounded by a collar to hold the lubricant in the area of the joint. When replacing the lubricant, the interior of the joints for the removal of the lubricant additionally each have a central lubricant channel per joint.

Eccentric screw pumps are frequently used in the food, pharmaceutical and medical sectors. These pumps must be cleaned frequently. It is especially to observe that strict hygiene standards are observed. In particular, when changing the product, it is important to remove all residues of a previous product or pumped medium completely when cleaning the eccentric screw pump. For this purpose, the pump must preferably be easy and quick to disassemble into individual parts that can be cleaned. If the cleaning is done in a so-called CIP process, in which the pump is not decomposed, it is particularly important that in the pump as possible no cavities, corners or the like are formed, in which residues can accumulate. CIP processes are "cleaning in place" or localized cleaning processes in which plants are cleaned on surfaces in contact with the product without substantial dismantling, in particular by flushing and / or decoction of the equipment. Particularly problematic in this respect, the pin joints, via which the rotor is movably connected to the drive shaft by means of a gimbal bearing. These joints are particularly susceptible to the accumulation of unwanted residues.

From the DE 101 16 641 A1 is a pin joint with a part of a drive shaft and a part of a coupling rod to remove. An end portion of the drive shaft is provided with a coaxial insertion receptacle. In this plug-in receptacle of the coupling pin of the coupling rod protrudes. To clean the interior of the Einsteckaufnahme whose wall knows two diametrical flushing holes.

The DE 10 2012 006 025 B3 discloses an open pin joint for an eccentric screw pump in the sanitary area with an inner and an outer condyle, each condyle having at least one diametrical bore penetrated by a pin capped at both ends. The inner joint head is provided on its front side with at least two channels which are arranged eccentrically to the longitudinal axis of the propeller shaft and extending from the longitudinal axis of the drive shaft in the direction of the outer side of the pin joint in each case by an angle A of 10 ° to 30 °. The holes are designed for the rinsing fluid to allow cleaning in the CIP process.

The Laid-Open Specification EP 1 683 970 A2 discloses an eccentric screw pump with a covered connection element for the rotationally fixed connection of the two rotor elements of the eccentric screw pump and a cover, wherein the connection element is separated in the mounted position by the cover from the interior of the pump housing.

The object of the invention is to further improve a pin joint for an eccentric screw, so that it is even easier to clean or even less opportunities to deposit promoted product.

The above object is achieved by a pin joint, an eccentric screw pump and method for producing a pin joint, comprising the features in the claims 1, 5 and 6. Further advantageous embodiments are described by the subclaims.

description

The present invention relates to an eccentric screw pump having at least one, preferably two pin joints. The eccentric screw pump comprises - as known from the prior art - a stator, a rotor and a drive shaft. The rotor is arranged on the drive shaft via a coupling rod, in particular the coupling rod is cardanically fixed between the rotor and the drive shaft via two pin joints. A pin joint each comprises a joint head, which is formed from an inner joint part and an outer joint part. The inner and the outer joint part each have a diametrical bore through which a bolt is guided. The bolt consists of a preferably cylindrical base part, at the free ends of each of which the cross-section of the bolt magnifying head parts are arranged and fixed. The head parts, for example, each have an internal thread, which are formed corresponding to external threads, which respectively form the two ends of the base part. Alternatively, the base part has at least one internal thread and the head part has a first area which can be screwed into the base part with an external thread and a second area with a cross-section which is larger than the base part.

In particular, a first head part is already connected before the passage of the bolt through the diametral holes of the joint parts positively and non-positively with the base part. In particular, this first head part is inseparably connected to the base part, for example, welded. The other, second head part is fastened to the base part after it has been passed through the diametral holes of the joint parts in order to connect them movably.

In order to prevent areas in the region of the screw connection between the base part and the second head part from arising in which the product that has been pumped can collect and deposit, it is provided that a sealing element is arranged in a boundary region between the base part and the second head part. The skilled person is clear that the described below attachment of the second head part can also be used in relation to the attachment of the first head part on the base part of the bolt.

According to a preferred embodiment, a groove is formed on at least one free end of the base part, in particular on at least the free end, on which the head part is arranged and secured only after passing through the hinge parts. Alternatively or additionally, a groove is formed on the side surface of at least one head part facing the free end of the base part. The sealing element is at least partially disposed within the groove. Preferably, the sealing element protrudes in the unscrewed state of the base part and the head part at least partially out of the groove or stands over.

The sealing element is preferably formed by a sealing ring or by a bonded sealant. When screwing base part and head part together is compressed by force and form closure of the sealing ring or the sealant and spreads in the aforementioned groove. As a result, the bolt in the boundary region between the base part and the head part is particularly well sealed against penetrating fluids.

According to one embodiment of the invention protrudes in the screwed state of the base part and the head part in the boundary region between the at least one base part and the head part, the sealing element laterally beyond the base part of the bolt. In particular, this means that the sealing element after screwing of the base part and the head part has an outer circumference which is larger than an outer circumference of the base part but smaller than an outer circumference of the head part.

The invention further relates to a pin joint for an eccentric screw pump described above, wherein in a boundary region between a base part of the bolt end and at least one head part of the bolt, a sealing element is arranged. Preferably, at least one free end of the base part and / or at least one side surface of a head part facing a free end of the base part comprises a groove. The sealing element can be arranged at least partially within the groove. The pin joint may alternatively or in addition to the features described have one or more features and / or properties of the eccentric screw pump described above.

The invention further relates to a method for producing a pin joint for an eccentric screw pump described above. For this purpose, a groove is milled in a free end region of the base part of the bolt. Alternatively or additionally, a groove is milled in a side surface of the head part facing the base part. The groove does not have to be deep, a flat milling is usually sufficient to achieve the desired result. In the groove a sealing ring is inserted, injected a sealant or otherwise introduced sealing material. Subsequently, the base part is screwed to the headboard. The sealant is compressed by force and positive locking. It is advantageously provided that in the assembled state of the bolt, the seal or the sealant protrudes laterally by a few mm above the base part of the bolt.

The method is used in particular for producing a previously described eccentric screw pump with a pin joint and / or for producing a previously described pin joint for an eccentric screw pump.

The method may comprise, as an alternative or in addition to the described features, one or more features and / or properties of the device described above. Likewise, the device may alternatively or additionally comprise one or more features and / or properties of the described method.

The eccentric screw pump or the pin joint described above is used above all in the hygiene sector for foodstuffs, in the field of pharmacy and / or for the promotion of medical products. It is important that all residues of a previous product or pumped medium are completely removed when cleaning the progressing cavity pumps. In the known from the prior art bolts of pin joints, there is always low entry of product or medium between the base part and the head part of the bolt. When cleaning the pump with the so-called CIP method, the above-mentioned residues can not be completely eliminated. The advantage of the invention described above over the prior art is in particular that this problem is avoided by the inventive bolt with seal.

figure description

• Figur 1 zeigt eine schematische Darstellung einer Exzenterschneckenpumpe gemäß dem Stand der Technik.
• Figur 2 zeigt einen schematischen Querschnitt durch ein Bolzengelenk einer Exzenterschneckenpumpe gemäß dem Stand der Technik.
• Figur 3 zeigt einen schematischen Querschnitt durch einen erfindungsgemäßen Bolzen für ein Bolzengelenk einer Exzenterschneckenpumpe.
• Figur 4 zeigt einen vergrößerten Teilausschnitt eines erfindungsgemäßen Bolzens für ein Bolzengelenk einer Exzenterschneckenpumpe.

In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail. The proportions of the individual elements to one another in the figures do not always correspond to the actual size ratios, since some shapes are simplified and other shapes are shown enlarged in relation to other elements for better illustration.

• FIG. 1 shows a schematic representation of a progressing cavity pump according to the prior art.
• FIG. 2 shows a schematic cross section through a pin joint of an eccentric screw pump according to the prior art.
• FIG. 3 shows a schematic cross section through a bolt according to the invention for a pin joint of an eccentric screw pump.
• FIG. 4 shows an enlarged partial section of a bolt according to the invention for a pin joint of an eccentric screw pump.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure. The illustrated embodiments are only examples of how the device according to the invention can be designed and do not represent a final limitation.

FIG. 1 shows a schematic representation of a progressing cavity pump 1 according to the prior art. This comprises a stator 3, a rotor 4 and a drive shaft 5. The rotor 4 is coupled via a coupling rod 6 and two pin joints 7 movable to the drive shaft 5. The stator 3 has a spiral-shaped inner side 3 *. The rotor 4 is designed as a rotor screw 4 * and performs an eccentric rotational movement about the stator longitudinal axis L. Due to the shape of rotor 4 and stator 3 formed between rotor 4 and stator 3 sealed cavities 2, which are axially upon rotation of the rotor screw 4 * in the conveying direction Move FR and promote the medium.

FIG. 2 shows a schematic cross section through a pin joint 7 of an eccentric screw pump 1 according to the prior art (see FIG. 1 ). The pin joint comprises a joint head 10, which is formed from an inner joint part 8 and an outer joint part 9. The inner and the outer joint part 8, 9 each have diametrical bores 11, 12, 12 *, through which a bolt 15 is guided. The bolt 15 consists of a base part 16 with a first head part 17, which is usually inextricably connected to the base part before assembly of the pin joint 7.

At the opposite end a second head part 18 is arranged. The base part 16 has at the free end, which is opposite to the first head part 17, a bore with an internal thread 19. The second head part 18 is formed, for example, as a kind of screw 20, wherein the screw head 21 has a larger cross-section than the base part 16. The screw 20 further has a threaded into the internal thread 19 of the base member 16 threaded portion 22 with an external thread 23. The bolt 15 without the second head part 18 is pushed through the diametral bores 11, 12, 12 * of the inner and the outer joint part 8.9 and then the second head part 18 is screwed into the base part 16. As a result, a movable connection of the two joint parts 8, 9 of the condyle 10 is produced.

FIG. 3 shows a schematic cross section through a bolt 15 * according to the invention for a pin joint 7 of a progressing cavity pump 1 (see Figures 1 and 2 ) and FIG. 4 shows an enlarged partial section of a bolt 15 according to the invention on the attachment of the first head part 17 * on the base part 16 * will not be discussed below. It is clear to the person skilled in the art that this can be done analogously to the attachment of the second head part 18 *, as described below.

The second head part 18 * is formed by a screw 20 *, which is at least partially screwed into an internal thread 19 * along the longitudinal axis X of the base part 16 * until the one side surface 24 * of the screw head 21 * touches the free end of the base part 16 * , In this so-called lower side surface 24 * a circumferential groove 30 is milled. The groove 30 is annular and has an inner and an outer periphery, the outer circumference substantially corresponding to the circumference of the base part 16 *.

In the groove 30, a sealing element 32 is arranged, for example, a sealing ring 33 is inserted or a sealant 34 injected. When screwing the Base part 16 * with the thus prepared head portion 18 * with groove 30 and sealing element 32, the sealing element 32 is compressed by force and positive engagement.

The arrangement of the groove 30 and the size of the sealing element 32 is chosen so that in the screwed state of the base part 16 * and second head portion 18 * the sealing element 32 projects laterally by a few mm over the base part 16 * of the bolt. As a result, an advantageous sealing of the connection between the base part 16 * and the second head part 18 * is achieved, so that no fluid can settle and the pin joint 7 (see FIG. 2 ) can be cleaned very easily.

The invention has been described with reference to a preferred embodiment. However, it will be apparent to those skilled in the art that modifications or changes may be made to the invention without departing from the scope of the following claims.

LIST OF REFERENCE NUMBERS

1

Cavity Pump

2

cavity

3.3 *

Stator, inside of the stator

4.4 *

Rotor, rotor screw

5

drive shaft

6

coupling rod

7

pin joint

8th

inner joint part

9

outer joint part

10

joint head

11

diametric bore

12.12 *

diametric bore

15

bolt

16

base

17

first headboard

18

second headboard

19

inner thread

20

screw

21

screw head

22

threaded portion

23

external thread

24 *

side surface

30

groove

32

sealing element

33

seal

34

caulk

FR

conveying direction

L

Statorlängsachse

X

Longitudinal axis of the bolt

Claims (8)

1. A pin joint (7) for an eccentric screw pump (1) comprising a stator (3), a rotor (4) and a drive shaft (5), wherein a coupling rod (6) is arranged gimbal-mounted by means of two pin joints between the rotor (4) and the drive shaft (5), wherein the pin joint (7) in each case comprises a joint head (10) constituted by an inner joint part (8) and an outer joint part (9), wherein the inner joint part (8) and the outer joint part (9) each comprise a diametrical bore (11, 12, 12*), through which a bolt (15, 15*) is passed, wherein the bolt (15, 15*) comprises a base part (16, 16*), to the free ends whereof head parts (17, 17*, 18, 18*) each enlarging the cross-section of the bolt (15, 15*) are fastened, characterised in that a sealing element (32) is arranged in the bordering region between the base part (16*) and at least one head part (18*) of the bolt (15*).
2. The pin bolt (7) according to claim 1,
   wherein at least one free end of the base part (16*) and/or at least one side face (24*) of a head part (18*) facing a free end of the base part (16*) comprises a groove (30).
3. The pin bolt (7) according to claim 1 or 2,
   wherein the sealing element (32) is arranged at least partially inside the groove (30) and wherein the sealing element (32) is constituted by a sealing ring (33) or by an adhesively bonded sealing compound (34) and/or wherein the sealing element (32) projects laterally beyond the base part (16*) in the bordering region between the at least one base part (16*) and the head part (18*).
4. The pin bolt (7) according to claim 3,
   wherein the sealing element (32) has an external circumference which is greater than an external circumference of the base part (16*) of the bolt (15*), but is smaller than the external circumference of the head part (18*) of the bolt (15*).
5. An eccentric screw pump (1) with a pin joint (7) according to any one of claims 1 to 5.
6. A method for producing a pin joint (7) for an eccentric screw pump (1), wherein the pin joint (7) comprises a joint head (10) comprising an inner joint part (8) and an outer joint part (9), wherein the inner joint part (8) and the outer joint part (9) each comprise a diametrical bore (11, 12, 12*), through which a bolt (15, 15*) is passed, wherein the bolt (15, 15*) comprises a base part (16, 16*), to the free ends whereof head parts (17, 17*, 18, 18*) each enlarging the cross-section of the bolt (15, 15*) are fastened, characterised in that, in the fastening of at least one head part (18*) to the base part (16*), a sealing element (32) is arranged in the bordering region between the base part (16*) and the head part (18*).
7. The method according to claim 6,
   wherein

   • at least one groove (30) is milled in a free end region of the base part (16*) of the bolt (15*) and/or in a side face (24*) of the head part (18*) facing the base part (16*),

   • a sealing ring (33) is inserted or a sealing compound (34) is injected into the at least one groove (30),

   • the base part (16*) is screwed with the head part (18*) and thereby

   • the sealing ring (33) or the sealing compound (34) is compressed by a friction-locked or form-fitting connection.
8. The method according to claim 6 or 7, wherein the method is used for the production of an eccentric screw pump (1) with pin joint (7) according to claim 5 and/or for the production of a pin joint (7) for an eccentric screw pump (1) according to any one of claims 2 to 5.

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