Shaft seal for a process plant

Abstract

Shaft seal for a process plant, which has at least one housing (14) with at least one housing wall (15), and a rotating shaft (13) which extends through an opening in the housing wall (15), wherein the shaft seal is designed as a sealing package (12) which seals the shaft (13), wherein the sealing package (12) is rotationally fixed to the rotating shaft (13) and that the sealing package (12) has a sealing disc (7) with a self-lubricating property which slides against the housing wall (15).

Description

[0001] The invention relates to a shaft seal for a process plant according to the preamble of patent claim 1.

[0002] A process engineering plant involves the crushing, agglomeration, separation and screening, mixing, as well as the storage and conveying of materials.

[0003] An example of a process engineering system is a mixer or a dosing and conveying screw. The process engineering system preferably has a housing, which forms the product space within which the product is processed. A shaft is arranged within the housing and extends from the housing. The shaft transmits rotational movements and torques. Such a shaft is supported by bearings, with the bearings transmitting the resulting radial and axial forces to the housing. The requirement is now to seal the shaft from the housing to prevent material from escaping from the housing.

[0004] Seals are used in process engineering systems where a transformation of material systems occurs through predominantly mechanical influences. The seals are designed to reduce or prevent the penetration or escape of gases, liquids, or solids at the points where components meet. A distinction is made between static (stationary) seals, which seal between components that do not move relative to each other, and dynamic seals (movement seals), which are used wherever components move relative to each other.

[0005] The disadvantage of dynamic seals is that when the rotating shaft vibrates, the material can work its way through the seal and ultimately escape from the housing.

[0006] US 7,178,806 B1 discloses a seal commercially available under the name CinchSeal. Such a seal is preferably used in screw conveyors and bulk material processing plants. The seal consists of a first flange, which is placed outside the housing on the rotating shaft. An elastomer seal and two rotor caps are then arranged on the shaft, which are surrounded by a seal housing. The housing is pressure-tight and is subjected to overpressure. Although the CinchSeal seal can seal off shaft vibrations to a certain extent, its design is very complex because a pressure-tight housing is required. Furthermore, the seal package of the CinchSeal seal must be positioned opposite the rotating shaft.

[0007] The invention is therefore based on the object of developing a shaft seal for a process plant in such a way that it is constructed in a simpler and more cost-effective manner.

[0008] To achieve the stated object, the invention is characterized by the technical teaching of claim 1.

[0009] An essential feature of the invention is that the sealing package is connected to the rotating shaft in a rotationally fixed manner and that the sealing package has a sealing disc with a self-lubricating property that slides against the housing wall.

[0010] In a first preferred embodiment, the seal assembly forms a unit that is arranged on the rotating shaft of the process plant. The seal assembly is connected to the shaft and rotates with it. It is thus a follower seal.

[0011] The seal package features a sealing washer that is in contact with the surface of the housing. Thus, there is no relative movement between the shaft and the seal, but rather between the sealing washer and the housing or the shaft bearing support.

[0012] In a preferred embodiment, the sealing disc is made of polyetheretherketone (PEEK). Preferably, the sealing disc is made of polyetheretherketone + solid lubricant (PEEK-TX), which is particularly suitable for use in the food industry and has excellent wear and sliding properties.

[0013] In another preferred embodiment, the sealing washer is designed as a type of thrust washer, which offers high wear resistance and a long service life. The use of such a sealing washer is a cost-effective and space-saving solution for axially guiding the shaft relative to the housing or the shaft bearing mount.

[0014] The above-mentioned materials all exhibit self-lubricating properties and are used, for example, as bushings, seals, bearings, or retaining rings. The self-lubricating properties of the sealing disc allow for the elimination of components in the sealing package, while simultaneously reducing maintenance requirements.

[0015] The rotating shaft of the process plant extends through an opening in the housing. The opening is designed, for example, as a bore. The seal assembly is arranged on the shaft outside the housing, with the self-lubricating sealing disc of the seal assembly being in direct sliding contact with the surface of the housing. The seal assembly is firmly connected to the shaft and rotates with it. Consequently, the sealing disc also rotates and is in sliding contact with the housing surface. The housing wall or the surface of the housing is preferably free of grooves in the contact area of ​​the sealing disc, so that good sliding friction is achieved.

[0016] The sealing disc of the seal assembly has a circular recess for the shaft. A sealing ring is preferably arranged in the recess of the sealing disc, which acts as a shaft seal and provides a seal against the shaft. The shaft seal is made of silicone, for example, and is designed as a flat seal or a grooved ring.

[0017] In general, the sealing ring provides sufficient sealing against the shaft. To increase the sealing effect, a compressive force is applied to the sealing ring, causing it to expand or compress radially. The necessary compressive force is generated by a thrust ring. The thrust ring has an axial projection that, when installed, is in contact with the sealing ring and transfers the compressive force to the sealing ring. The diameter of the projection approximately corresponds to the diameter of the sealing ring.

[0018] The thrust ring can also be referred to as a drive ring or shaft seal retainer and is preferably made of a metallic material. However, other materials, such as plastics or fiber-reinforced plastic, are also possible.

[0019] The thrust ring is located between the sealing washer and a mounting flange. The thrust ring is attached to the sealing washer with cylinder head screws (e.g., M5). For this purpose, the sealing washer preferably has holes with internal threads. When installing the thrust ring, the cylinder head screws are only loosely tightened so that the thrust ring is positioned with a certain amount of play relative to the sealing washer and does not yet squeeze the shaft seal.

[0020] The mounting flange is mounted on the sealing washer using set screws. These set screws have a stepped collar that defines the distance between the sealing washer and the mounting flange. These set screws are therefore referred to as spacers. The spacers primarily serve as assembly aids. After the seal package has been installed on the shaft, the spacers are removed.

[0021] To connect the sealing washer to the mounting flange, the spacers are inserted through holes in the mounting flange and screwed into internal threads in the sealing washer. Since the screw head of the spacer is larger than the hole diameter in the mounting flange, a detachable connection is created between the two components. The preload can be increased by placing washers underneath.

[0022] Since the spacers are screwed into the threads of the sealing washer, and the sealing washer is made of plastic, installation is preferably done by hand to avoid excessive force. After complete assembly and installation of the sealing package, the spacers can be removed again.

[0023] The mounting flange can also be referred to as the base flange and is preferably made of a metallic material. However, other materials, such as plastics or fiber-reinforced plastic, are possible.

[0024] The mounting flange has several threaded holes through which the compression springs are inserted. The compression springs are helical compression springs or spiral springs made of metal, which are elastically deformable. However, other elastic elements, such as disc springs, rubber elements, hydraulic elements, or similar, can also be used instead of compression springs.

[0025] Preferably, the sealing disc has circular recesses aligned with the holes in the mounting flange, into which the compression spring engages and is held securely against possible slipping.

[0026] After inserting the compression springs into the holes in the mounting flange, the guide screws are screwed into the threads of the holes. The guide screws are M16 screws, for example, which are tightened to a defined torque. The preload on the sealing washer can be adjusted using the guide screws and compression springs.

[0027] The assembled seal assembly is now placed on the shaft and pushed against the housing wall. The surface of the sealing washer is in contact with the housing surface.

[0028] The seal package is attached to the shaft using a rotationally fixed connection, preferably a shaft-hub connection. The shaft-hub connection can be, for example, a force-locking connection (frictional engagement), a positive connection, a preloaded positive connection, or a material connection.

[0029] In a preferred embodiment, the shaft-hub connection has radial pins (e.g. threaded pins, grub screws) which are inserted through holes in the fastening flange and engage in grooves or recesses provided for this purpose in the shaft.

[0030] After positioning and securing the seal assembly on the shaft, the cylinder head screws can be tightened. The thrust ring exerts a compressive force on the seal ring, compressing or squeezing it and pushing it further against the shaft. This further increases the sealing effect between the sealing disc and the shaft.

[0031] The shaft screws, which were used as spacers and assembly aids, can then be unscrewed from the mounting flange again.

[0032] The entire seal assembly now rotates with the shaft. Sealing is achieved via the sealing washer and the sealing ring. The pressure on the sealing washer can be adjusted using the compression springs on the mounting flange and the spacers.

[0033] Preferably, in the sealing package according to the invention, the diameters of the sealing washer and the mounting flange are the same. However, the invention is not limited to this. Rather, it is possible for the sealing washer, for example, to have a smaller diameter than the mounting flange. Or the sealing washer may have a stepped collar, thereby reducing the contact area between the housing surface and the sealing washer.

[0034] In a preferred embodiment, the process plant is a mixer or a kneader which is used in the food industry.

[0035] The sealing package according to the invention therefore has the following functional principles: • The preload can be adjusted using spacers (=shaft screws) and compression springs; • The seal package is pushed onto the shaft and held in the end position; • The seal package has a mounting flange which is clamped onto the shaft with the three threaded pins (grub screws); • Once the seal package is firmly seated on the shaft, the four spacers are removed again. • Due to the axial fixation of the mounting flange on the shaft, the compression springs now exert a compressive force on the sealing washer, which presses it against the sealing surface of the housing wall; • There is no relative movement between the rotating shaft and the sealing disc, but rather a relative movement between the sealing disc and the rigid housing wall; • There are cylindrical pins between the sealing washer and the mounting flange, which ensure that the sealing washer is driven when the shaft rotates.

[0036] The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another.

[0037] All information and features disclosed in the documents, including the abstract, in particular the spatial configuration shown in the drawings, are claimed as essential to the invention insofar as they are new, individually or in combination, compared to the prior art.

[0038] The invention is explained in more detail below with reference to drawings illustrating only one embodiment. Further essential features and advantages of the invention will become apparent from the drawings and their description.

[0039] They show: Fig. 1: Perspective view of the sealing package Fig. 2: Exploded view of the sealing package Fig. 3: schematic representation of the sealing package on the shaft Fig. 4: Top view of the sealing package showing the sections AA, BB and FF Fig. 5: schematic representation of section AA Fig. 6: schematic representation of section BB Fig. 7: Schematic representation of the cut FF Fig. 8: schematic side view of the sealing package Fig. 9: further design of the sealing package with grooved ring Fig. 10: schematic representation of the seal package in the installed state on a shaft

[0040] With the Fig. Figure 1 shows the sealing package 12 according to the invention in its assembled state. The sealing package 12 consists of a round sealing disc 7 made of a self-lubricating material. The sealing disc 7 has several recesses 23 in which the compression springs 3 are arranged. The compression springs 3 are located between the sealing disc 7 and the mounting flange 1.

[0041] The Fig. Figure 1 shows the assembled seal assembly 12, but the seal assembly 12 is not yet mounted on a shaft. For this reason, the spacers 9 are still located in the respective holes of the mounting flange 1 and the corresponding threads 24 of the sealing washer 7.

[0042] With the Fig. Figure 2 shows an exploded view of the seal assembly 12. The sealing disc 7 is preferably made of PEEK-TX material and has a circular recess 18 in the center for the shaft 13. The round shaft seal 5 is inserted into a receptacle 25 in the circular recess 18 of the sealing disc 7.

[0043] The thrust ring 4 is placed on the sealing washer 7 and secured with cylinder head screws 6. The thrust ring 5 has a round shoulder whose diameter approximately corresponds to the diameter of the recess 18. When the sealing package 12 is assembled, the shoulder presses on the shaft seal 5. The thrust ring 4 is designed as a driving ring and has a total of four protruding eyelets for cylindrical pins 10 on its circumference. The cylindrical pins 10 are arranged opposite the sealing washer 7 and enable axial movement of the thrust ring 4. The pressure force on the shaft seal 5 can be adjusted using the cylinder head screws 6.

[0044] The fastening flange 1 is located above the pressure ring 5. The fastening flange 1 has a similar diameter to the sealing washer 7 and is preferably made of a metallic material.

[0045] Distributed around the circumference are a total of eight holes with internal threads for the guide screws 2. The guide screws 2 are inserted into the holes 21 together with compression springs 3. Preferably, the sealing washer 7 has small recesses aligned with the holes 21 of the mounting flange 1 for the positive reception of the compression springs 3.

[0046] On the outer circumference of the mounting flange 1, there are additional holes for threaded pins 8 and positioning pins 11, which are components of the shaft-hub connection. With the help of the shaft-hub connection, the entire seal package 12 is firmly connected to the shaft 13 and aligned relative to the shaft 13. For this purpose, the shaft 13 has recesses and / or grooves, which in particular enable the seal package 12 to be positioned axially on the shaft 13. The seal package 12 must be positioned such that, when installed, the sealing disc 7 of the seal package 12 is in contact with the housing wall of the process plant.

[0047] Fig. Figure 3 shows the seal assembly 12 installed on a shaft 13. The shaft 13 has several sections, one section extending through the housing wall 15 of a housing 14 of a process plant. Preferably, one or more bearings for the shaft 13 are located in the area of ​​the housing wall 15, although these are not shown.

[0048] The seal assembly 12 includes a sealing washer 7 made of a self-lubricating material. The sealing washer 7 is in direct contact with the housing wall 15. Upon radial movement of the shaft 13, the seal assembly 12 rotates, creating sliding friction between the sealing washer 7 and the housing wall 15.

[0049] According to the Fig. 3 further shows that the sealing disc 7 has a receptacle 25 within which the shaft seal 5 is arranged. The shaft seal 5 seals the shaft 13 and prevents any substance from escaping from the housing 14.

[0050] Fig. 4 shows the sealing package 12 with a top view and the course of the sections AA, BB, and FF.

[0051] With the Fig. 5 the section AA of the Fig. 4. The sealing package 12 essentially consists of a sealing washer 7, a shaft seal 5, a thrust ring 4, and a mounting flange 1.

[0052] The sealing disc 7 has a receptacle 25 for the shaft seal 5. The receptacle 25 is designed as a shoulder within the recess 18 and prevents the shaft seal 5 from slipping out of the sealing disc 7. On the opposite side is the thrust ring 4, which presses against the shaft seal 5 with the projection 19 and deforms it.

[0053] Fig. 6 shows the section BB of the Fig. 4. The seal package 12 is pre-assembled. The spacers 9 are used to achieve a defined distance between the sealing washer 7 and the mounting flange 1. The spacers 9 are used for the assembly of the guide screws 2 and compression springs 3. The spacers 9 allow the vertical distance between the sealing washer 7 and the mounting flange 1 to be determined. This is particularly necessary for the correct assembly of the seal package 12 on the shaft 13. Reference numeral 17 indicates the preload, which can be adjusted during assembly.

[0054] Fig. 7 shows the section FF of the Fig. 4. The cylindrical pins 10 are used to fix the pressure ring 4 and are clamped in the desired position with the positioning pins 10.

[0055] Fig. 8 shows the sealing package 12 in a side view, wherein the compression springs 3 are arranged between the sealing disc 7 and the fastening flange 1.

[0056] Fig. Figure 9 shows a further embodiment of the seal assembly 12, wherein the shaft seal 5 is designed as a grooved ring, which is arranged in the recess 18 of the sealing disc 7. The grooved ring rests on the receptacle 25, which is designed as a radial shoulder.

[0057] With the Fig. Figure 10 shows the seal package 12 in the installed state. Two bores 28 and two recesses 26 are located in the housing wall 15. This shows, for example, a design with a built-in shaft 13 and a design without a built-in shaft 13.

[0058] The seal assembly 12 is arranged on a shaft 13, which extends through a bore 28 in the housing wall 15 of a housing 14. In the area of ​​the bore 28, the housing wall 15 has a circular recess 26 with a sealing surface 27 for the seal assembly 12. When the seal assembly 12 is installed, the sealing disc 7 rests against the sealing surface 27, whereby a relative movement occurs between the sealing disc 7 and the sealing surface 27 of the rigid housing wall 15 upon rotation of the shaft 13. Drawing legend 1 mounting flange 2 guide screws 3 compression spring 4 pressure ring 5 Shaft seal 6 cylinder head screw 7 Sealing washer 8 threaded pin 9 spacers 10 cylindrical pin 11 Positioning pin 12 Sealing package 13 Wave 14 housings 15 housing wall of 14 16 Contact surface 17 Preload 19 lead of 4 20 paragraph of 7 21 Hole for 2 22 Hole for 9 23 Deepening 24 threads for 9 25 recording for 5 26 recess for 12 27 Sealing surface of 26 or 15 QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 7,178,806 B1

[0006]

Claims

[1] Shaft seal for a process plant, which has at least one housing (14) with at least one housing wall (15), and a rotating shaft (13) which extends through an opening in the housing wall (15), wherein the shaft seal is designed as a sealing package (12) which seals the shaft (13), characterized by that the sealing package (12) is connected to the rotating shaft (13) in a rotationally fixed manner and that the sealing package (12) has a sealing disc (7) with a self-lubricating property, which slides against the housing wall (15). [2] Shaft seal according to claim 1, characterized by that the sealing washer (7) consists of polyetheretherketone (PEEK) or polyetheretherketone and a solid lubricant (PEEK-TX). [3] Shaft seal according to claim 1 or 2, characterized bythat the sealing disc (12) has a shaft seal (5) for sealing the outer circumference of the shaft (13), wherein the shaft seal (5) is designed as a flat seal or as a grooved ring. [4] Shaft seal according to one of claims 1 to 3, characterized by that the sealing package (12) has a sealing disc (12) and a fastening flange (1), wherein between the sealing disc (12) and the fastening flange (1) there are guide screws (2) with compression springs (3) which, starting from the fastening flange (1), exert a compressive force on the sealing disc (7) directed in the axial direction of the shaft (13). [5] Shaft seal according to one of claims 1 to 4, characterized byin that the sealing package (12) has a sealing disc (12) and a fastening flange (1), wherein a pressure ring (4) is arranged between the sealing disc (12) and the fastening flange (1), which pressure ring exerts a pressure force directed in the axial direction of the shaft (13) on a shaft seal (5) in the sealing disc (7). [6] Shaft seal according to claim 5, characterized by that the pressure ring (4) is fastened to the sealing washer (7) with cylinder head screws (6), wherein the pressure force of the pressure ring (4) on the shaft seal (5) can be adjusted by means of the cylinder head screws (6). [7] Shaft seal according to one of claims 1 to 6, characterized by that the rotationally fixed connection between the seal package (12) and the shaft (13) is designed as a shaft-hub connection. [8] Shaft seal according to one of claims 1 to 7, characterized bythat there is a rotationally fixed shaft-hub connection between the mounting flange (1) and the shaft (13). [9] Shaft seal according to one of claims 1 to 8, characterized by that the mounting flange (1) is made of a metal material. [10] Shaft seal according to one of claims 1 to 9, characterized by that the process plant is a mixer or kneader and is used in the food industry.

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