Patent Publication Number: US-2019178385-A1

Title: Mechanical seal device with a simplified structure

Description:
The present invention relates to a mechanical seal device with a simplified structure, wherein in particular a disassembly of the mechanical seal device can be carried out easily from an atmospheric side. 
     Mechanical seal devices are known from the state of the art in various embodiments. What is known from DE 1 0201 30071 65 B4, for example, is a mechanical seal device that has a retaining ring for retaining a stationary slide ring, wherein the retaining ring is connected to a housing by means of a clamp connection. At that, the clamp connection is arranged at a product side of the mechanical seal device. In this manner, necessary supply lines can be arranged freely inside the housing, whereby in particular most varied kinds of customers&#39; wishes can be realized when it comes to the arrangement of such supply lines. At that, the mechanical seal device is mounted in the axial direction on a shaft or the like. After a certain number of operating hours, it may be necessary to replace the slide rings and other wear parts of the mechanical seal device. Here, it has been found that clotting from the product may occur at the clamp connection and/or at the shaft sleeve, for example if the mechanical seal device is used in pumps with an extremely sticky product at a product side, such as e.g. concrete or tar, or the like. This may result in difficulties when the mechanical seal device is being pulled off in the axial direction. Here, the mechanical seal device can often be detached from the shaft only by excessive force and/or with some destruction occurring. 
     Therefore, it is the objective of the present invention to provide a mechanical seal device which in particular facilitates disassembly from an atmospheric side in all application cases, while at the same time having a simple structure as well as a simple, cost-effective manufacturability, with it still being possible to arrange the supply lines of the mechanical seal device inside a housing as freely as possible. 
     The objective is achieved through a mechanical seal device having the features of claim  1 , with the subclaims showing preferred further developments of the invention. 
     The mechanical seal device according to the invention with the features of claim  1  comprises at least one mechanical seal with a rotating and a stationary slide ring that delimit a sealing gap in between them. What is further provided is a retaining ring for retaining the stationary slide ring. Further, the mechanical seal device comprises a housing, wherein a clamp connection by means of a clamping mechanism is provided between the housing and the retaining ring. To achieve accessibility to the clamp connection from an atmospheric side, at least one axial through hole is provided inside the housing, connecting the product side of the housing to the atmospheric side of the housing. Here, the clamping mechanism comprises a screw bolt and a clamping element, wherein the screw bolt is arranged inside the passage opening. The clamping element has a threaded opening into which the screw bolt is screwed in, wherein the clamping element is further embodied in such a manner that a contact surface of the clamping element abuts the retaining ring to form the clamp connection. Thus, it is possible to screw the screw bolt in and also to screw it out again from the atmospheric side. In this manner, also a partial disassembly from the atmospheric side is possible if the mechanical seal device cannot be pulled off the shaft or the like in the axial direction as a result of clotting by a product to be sealed, or the like. By loosening the screw bolt, the housing of the mechanical seal device can be removed, and subsequently further individual parts of the mechanical seal device can be simply dismantled. 
     For a particularly easy disassembly, the screw bolt has a head with a tool attachment projection at an end that is located at the atmospheric side. 
     Further, the housing preferably has a recess inside of which the clamping element is arranged. In this manner, a very compact design can be obtained in the axial direction of the mechanical seal device. Further, the use of the recess facilitates that the clamping element is stopped from rotating, e.g. due to geometrical stop surfaces or the like, when the screw bolt is screwed into the clamping element. 
     To avoid any twisting of the clamping element as the screw bolt is being screwed in and/or screwed out, the clamping element has a threaded opening, with its central axis being arranged so as to be offset with respect to a center line of the clamping element. 
     The clamping element is preferably a sliding block, wherein the threaded opening in the clamping element is completely passed through the sliding block in the axial direction. It is especially preferred if the sliding block is formed in a cylindrical manner and the threaded opening in the sliding block is provided off center with respect to a central axis of the sliding block. Alternatively the sliding block can also be embodied as a square or a hexagon, or in general as a polygon. The sliding block can also have one or two oppositely arranged contact surfaces for abutting the housing so as to avoid any co-rotation of the sliding block during a screwing process. 
     The housing of the mechanical seal device preferably consist of a single part. In this manner, the most varied arrangements of supply channels inside the housing can be realized, which makes it possible to meet special customers&#39; wishes. 
     It is particularly preferred if at least one supply line, preferably two supply lines, namely one supply line and one return line for a barrier fluid or the like, are provided inside the housing. 
     It is particularly preferred if the mechanical seal device is provided as a cartridge, i.e. as a unit that can be pre-assembled. In this manner, it is in particular ensured that the mechanical seal device can be mounted on a shaft or the like in a particularly quick manner. 
     Further, it is particularly preferred if multiple clamping mechanisms are arranged along a circumference, in particular if they are arranged equidistantly in the circumferential direction. 
     To provide a protection, in particular for the slide rings of the mechanical seal device, the housing preferably extends over the slide rings. 
     Here, the mechanical seal device according to the invention can be provided as a simple mechanical seal device, i.e. having exactly one mechanical seal, or alternatively also as a double mechanical seal device with two separate mechanical seals. 
     The mechanical seal device is preferably used in applications with pumps. 
     Further, the present invention relates to a pump for pumping viscous and/or sticky media with a mechanical seal device according to the invention. 
    
    
     
       In the following, a preferred exemplary embodiment of the invention is described in more detail by referring to the accompanying drawing. In the drawings: 
         FIG. 1  shows a schematic sectional view of a mechanical seal device according to an exemplary embodiment of the invention, and 
         FIG. 2  shows a schematic top view on a clamping element of the mechanical seal device of  FIG. 1 . 
     
    
    
     In the following, a mechanical seal device  1  according to a preferred exemplary embodiment of the invention is described in detail based on  FIGS. 1 and 2 . 
     As can be seen in  FIG. 1 , the mechanical seal device  1  comprises a first mechanical seal  10  and a second mechanical seal  100 . The first mechanical seal  10  comprises a rotating slide ring  2  and a stationary slide ring  3  that delimit a sealing gap  4  in between them. The second mechanical seal  100  comprises a rotating slide ring  102  and a stationary slide ring  103  that delimit a sealing gap  104  in between them. 
     The mechanical seal device  1  seals a product side  13  off against an atmospheric side  14  at the shaft  70 . 
     The mechanical seal device is preferably used in a pump, or the like. 
     As can be seen in  FIG. 1 , the mechanical seal device is mounted on a shaft sleeve  7 . The mechanical seal device  1  is provided as a cartridge, so that the mechanical seal device  1  can be preassembled on the shaft sleeve  7  and can be simply slid onto the shaft  70  in the axial direction X-X of the shaft. 
     The mechanical seal device  1  further comprises a retaining ring  5  that retains the stationary slide ring  3  of the first slide ring seal  10 . 
     Further, the mechanical seal device  1  comprises a single-part housing  6  that extends over the two mechanical seals  10 ,  100  in the axial direction X-X. By providing the single-part housing  6 , the supply lines, such as e.g. the first media duct  11  and the second media duct  12  indicated in  FIG. 1 , can be arranged in the housing  6  in any desired manner as in comparison to mechanical seal devices having a divided housing, with the housing comprising at least two parts. 
     The retaining ring  5  is fixated at the housing  6  by means of a clamp connection. The clamp connection is provided by a clamping mechanism  8 , comprising a screw bolt  80  and a clamping element  82 . 
     As can be seen in  FIG. 1 , a through hole  60  is provided in the housing  6 , extending in the axial direction X-X in the housing from a product side  13  to an atmospheric side  14 . 
     Further, a recess  61  is provided in the housing  6  to receive the clamping element  82 . The screw bolt  80  is passed through the through hole  60  inside the housing  6 . 
     The screw bolt  80  comprises a cylindrical body provided with a thread, as well as a head  81 , with the head  81  being oriented towards the atmospheric side  14  and being arranged in the housing  6  in a countersunk manner. 
     As can be seen in  FIG. 1 , the retaining ring  5  is clamped between a ledge  62  of the housing  6  and the clamping element  82 . Here, the clamping element  82  has a threaded opening  83  into which the screw bolt  80  is screwed in. The clamping element  82  further comprises a contact surface  84  which abuts the retaining ring  5  at a clamping surface  50 . 
     As can be seen in  FIG. 1 , the retaining ring  5  is thus clamped between the contact surface  84  and the ledge  62  in the housing  6 . Here, the clamping process can be carried out by screwing the screw bolt  80  into the threaded opening  83  of the clamping element  82 . In this manner, the clamping element  82  is pulled in the direction towards the atmospheric side  14 , so that the clamp connection is realized. 
     Because the head  81  of the screw bolt  80  is arranged at the atmospheric side  14 , the housing  6  can be detached from the retaining ring  5  from the direction of the atmospheric side  14 . This is for example necessary when wear parts have to be maintained and/or replaced, such as e.g. in the case of a replacement of the slide rings or the like. At that, the screw bolt  80  can be screwed out of the clamping element  82  at a tool attachment projection formed at the head  81 . 
       FIG. 2  schematically shows a top view on the clamping element  82 . As can be seen in  FIG. 2 , a central axis  16  of the threaded opening  83  is arranged so as to be offset with respect to a center line  15  of the clamping element  82 . The clamping element  82  of this exemplary embodiment is a cylindrical element, e.g. a cylindrical sliding block. 
     Since the threaded opening  83  is arranged off center in the cylindrical clamping element  82 , a co-rotation of the clamping element  82  can be avoided as the screw bolt  80  is being screwed in or out of the threaded opening  83 . Here, the clamping element always abuts the walls of the recess  61  inside the housing  6 . 
     If a maintenance procedure becomes due in the mechanical seal device according to the invention, the disassembly of the mechanical seal device  1  can be carried out in a simple manner from the atmospheric side  14  if it should not be possible to pull off the complete mechanical seal device from the shaft  70  in the axial direction X-X. This may in particular occur if the product to be sealed is for example very sticky or very viscous, such as e.g. concrete or tar, or the like. If thus the mechanical seal device cannot be completely pulled off, the screw bolts  80  can be loosened, and at first the housing  6  can be dismounted and subsequently the further individual parts of the slide ring seal can be correspondingly removed. 
     Thus, according to the invention, a maintenance procedure of mechanical seal devices can be rendered considerably easier, without having to accept the disadvantages of a divided housing. 
     By providing the clamp connection between the single-part housing  6  and the retaining ring  5 , a secure connection of the housing can thus be facilitated, and in particular an embodiment of the mechanical seal device as a cartridge, which has advantages with respect to mounting and offers security against any damage to sensitive components of the mechanical seal device, can be provided. 
     Further, the housing  6  covers the two slide ring seals  10 ,  100  in the axial direction. Here, it should be understood that it is not absolutely necessary that a tandem arrangement with two mechanical seals be provided, but rather that it is also possible to provide only one individual mechanical seal. 
     PARTS LIST 
       1  mechanical seal device 
       2  rotating slide ring 
       3  stationary slide ring 
       4  sealing gap 
       5  retaining ring 
       6  housing 
       7  shaft sleeve 
       8  clamping mechanism 
       10  first slide ring seal 
       11  first media duct 
       12  second media duct 
       13  product side 
       14  atmospheric side 
       15  center line 
       16  central axis 
       50  clamping surface 
       60  through hole 
       61  recess in the housing 
       62  ledge 
       70  shaft 
       80  screw bolt 
       81  head 
       82  clamping element 
       83  threaded opening 
       84  contact surface 
       100  second mechanical seal 
       102  rotating slide ring 
       103  stationary slide ring 
       104  sealing gap 
     X-X axial direction