Patent Publication Number: US-2021172529-A1

Title: Floating ring seal

Description:
The invention relates to a floating ring seal for sealing on a rotating component, especially a rotating shaft, having significantly reduced weight and simplified design. 
     Floating ring seals are known from prior art in various configurations. For example, floating ring seals are used to seal pump shafts in high speed pumps. The floating ring seals are in a floating arrangement on the shaft, allowing them to follow an appropriate radial deflection especially in the case of the shaft&#39;s radial deflection. An issue with floating ring seals is the permanent gap between the floating ring seal and the rotating component, where relatively strong leakage occurs. For this reason, several floating ring seals are usually arranged in series. However, this results in considerable constructional effort and, in particular, large installation space required in the axial direction of the component to be sealed, which increases the total installation length of the pump or the like, something that such pump manufacturers want to avoid as far as possible. 
     It is therefore the object of the invention to provide a floating ring seal for sealing on a rotating component, which floating ring seal is able to especially reduce any axial overall length of the seal with a simple and inexpensive design. Furthermore, it is the object of the present invention to provide a component arrangement including a floating ring seal according to the invention. 
     This object will be solved by a floating ring seal having the features of claim  1  and a component arrangement having the features of claim  9 . The respective subclaims show preferred embodiments of the invention. 
     In addition to easier assembly/disassembly, the floating ring seal according to the invention for sealing on a rotating component provides significant weight advantage. According to the invention, the floating ring seal comprises a one-piece body including a first and a second throttling area directed radially inward. The throttling areas are separated from each other by a first circumferential groove on the inner circumference of the body. The groove is located between the first and second throttling area. The design of a one-piece floating ring seal comprising two throttling areas, wherein each of which is directed towards the rotating component, and having a throttling gap between the rotating component and the two throttling areas, results in significant weight advantage as compared to two individual prior art floating ring seals. In comparison to two individual floating ring seals, the total mass of the floating ring seal according to the invention can be reduced by approx. 40%. 
     Preferably, a width of the first throttling area in the axial direction of the floating ring seal is smaller or equal to a second width of the throttling area in the axial direction of the floating ring seal. This increases the throttling effect of the second throttling area, reducing overall leakage of the floating ring seal. 
     Another great advantage of the arrangement according to the invention having two throttling areas with a groove arranged in between resides in that a leakage flow, which flows across the first throttling area towards the second throttling area, is slowed down in the groove, so that the leakage will subsequently be significantly reduced across the second throttling area. Herein, the leakage flow can especially provide a counter flow. 
     Especially preferred is a groove width which is smaller than or equal to the first width of the first throttling area and/or which is smaller than or equal to the second width of the second throttling area. 
     According to another preferred embodiment of the invention, the one-piece body further comprises a third throttling area directed radially inward. The third throttling area is arranged in series to the second throttling area. Furthermore, a second circumferential groove is arranged between the second and third throttling areas on an inner circumference of the body. 
     The one-piece body preferably includes a fourth throttling area. A third circumferential groove is formed between the third and fourth throttling area on the inner circumference of the one-piece body. Thus, such a floating ring seal comprises four throttling areas and three circumferential grooves. 
     A carbon floating-ring seal is particularly preferred. Due to the one-piece design of the floating ring seal, significant cost reduction during manufacture can also be achieved, especially as a carbon floating ring seal. 
     According to another preferred embodiment of the invention, the floating ring seal furthermore comprises a seal ring carrier. The seal ring carrier is a separate component, holding the one-piece floating ring seal. The seal ring carrier preferably is arranged on a side of the one-piece body opposite to the throttling areas. 
     Preferably, the floating ring seal also comprises a housing, especially a titanium housing, including a recess for loosely retaining the one-piece body or the one-piece body with the seal ring carrier. 
     Furthermore, the present invention relates to a component arrangement comprising a floating ring seal according to the invention as well as a rotating component, especially a shaft. Especially preferably, the shaft is a pump shaft or a compressor shaft. 
     The component arrangement comprises a first throttling gap between the first throttling area of the one-piece body of the floating ring seal and the rotating component as well as a second throttling gap between the second throttling area of the one-piece body and the rotating component. Further preferably, the throttling areas and the surface of the rotating component are designed such that a gap height of the first throttling gap and/or the second throttling gap remains constant in axial direction. Preferably, a gap height of the first throttling gap is the same as a gap height of the second throttling gap. 
     Preferably, the component arrangement is a pump or a compressor or a turbine. The component arrangement is preferably operated at very high speeds. 
    
    
     
       In the following, preferred example embodiments of component arrangements comprising floating ring seals are described in detail, while reference will be made to the accompanying drawing, wherein: 
         FIG. 1  is a schematic sectional view of a component arrangement comprising a floating ring seal, according to a first example embodiment of the invention, 
         FIG. 2  is a schematic, perspective view of a component arrangement comprising a floating ring seal, according to a second example embodiment of the invention, and 
         FIG. 3  is a schematic, perspective view of a component arrangement comprising a floating ring seal according to a third example embodiment of the invention. 
     
    
    
     Referring now to  FIG. 1 , a component arrangement  1  comprising a floating ring seal  2  will be described in detail below, according to a first example embodiment of the invention. 
     As can be seen from  FIG. 1 , the floating ring seal  2  comprises a one-piece body  20  and a seal ring carrier  6 . The seal ring carrier  6  is adapted to retain the one-piece body  20 . 
     The one-piece body  20  comprises a first throttling area  21  and a second throttling area  22 . The first throttling area  21  is located at a radially inward directed region of the one-piece body  20 . The second throttling area  22  is also located on the radially inward directed region of the one-piece body  20 . 
     As can be seen from  FIG. 1 , the floating ring seal  2  seals a product region  10  from an atmosphere region  11  on a shaft  3 . A first throttling gap  8  is formed between the first throttling area  21  and a surface of the shaft  3 , and a second throttling gap  9  is formed between the second throttling area  22  and the surface of the shaft  3 . 
     A groove  23  is arranged between the first throttling area  21  and the second throttling area  22  in the axial direction X-X of the floating ring seal  2 . The groove  23  is formed throughout around the inner circumference of the one-piece body  20 . 
     A first width B 1  of the first throttling area  21  in axial direction X-X is smaller than a second width B 2  of the second throttling area  22 . Furthermore, a width N 1  of the groove  23  in axial direction X-X is smaller than the first width B 1  and the second width B 2 . 
     A first gap height at the first throttling gap  8  remains constant in axial direction X-X. A second gap height at the second throttling gap  9  in axial direction is also constant. The gap heights of the first and second throttling gaps are preferably selected such that the second gap height at the second throttling gap  9  is the same as the first gap height at the first throttling gap  8 . 
     The floating ring seal  2  is located in a recess  5  in a housing  4 . The housing  4  has a multiple part design to allow assembly in the axial direction of the shaft  3 . As can be seen from  FIG. 1 , the floating ring seal  2  is arranged in recess  5  in a floating manner. This enables the floating ring seal  2  to follow the shaft movement in case of radial deflections of the shaft  3 , which may occur during operation. In this case, the radial shaft movement may cause a short contact between the shaft  3  and the one-piece body  20 . 
     The floating ring seal  2  also includes a locking mechanism  7  to allow it to be mounted in the body  4 . The locking mechanism  7  comprises a bolt  70  with a head  71 . As can be seen from  FIG. 1 , the bolt  70  is located in the seal ring carrier  6 . The head  71  protrudes in axial direction X-X and is located in a lateral notch  50  in the recess  5 . In the lateral notch  50 , a radial clearance is provided for the head  71  such that the floating ring seal  2  is enabled to follow the radial deflections of the shaft described above. This is indicated by the double arrow A. 
     In order to enable the floating ring seal  2  to accommodate the radial deflections described above, a projection  40  is formed on the housing  4 , projecting in axial direction X-X. This allows safe guiding of the floating ring seal in recess  5 . The projection  40  also prevents the medium from circumventing the throttling gaps  8 ,  9  through a path behind the floating ring seal  2 . 
     The projection  40  is provided so as to be completely circumferential in circumferential direction. 
     Thus, the two individual floating ring seals previously used in prior art technology can be replaced by the floating ring seal  2 . In particular, significant weight reduction of up to approx. 40% can be achieved. Furthermore, the one-piece design of the floating ring seal  2  allows much easier assembly and disassembly if the floating ring seal  2  is required to be replaced. As the locking mechanism  7  is still provided exclusively in the seal carrier  6 , the one-piece body  20  of the floating ring seal can be designed without incorporating weakening recesses, grooves or the like to accommodate a locking mechanism. This further reduces the weight of the body  20  and significantly extends service life of the one-piece body  20 . 
     During operation, some leakage occurs through the first throttling gap  8 , but the provision of the circumferential groove  23  significantly slows down the leakage flow velocity in the region of the groove  23 . Thus, another leakage through the second throttling gap  9  towards the atmosphere region  11  is again significantly reduced or can be completely avoided if necessary. 
     The depth of the groove  23  is selected such that in the region of the groove  23  at least partial return flow C of the leakage, which has reached the groove  23  through the first throttling gap  8 , occurs. This in addition reduces flow velocity of the leakage through the floating ring seal and minimizes further leakage through the second throttling gap  9 . 
       FIG. 2  shows a component arrangement  1  according to a second embodiment of the invention, wherein equal or operationally equal parts are designated by the same reference numbers. 
     As can be seen from  FIG. 2 , the component arrangement  1  comprises two separate floating ring seals  2  according to the invention. The basic structure of the floating ring seals  2  is the same as in the first example embodiment. However, as can be seen from  FIG. 2 , the floating ring seals  2  are arranged mirror-inverted to each other on the shaft  3 . Thus, a total of four throttling gaps are provided in the direction from the product region  10  to the atmosphere region  11 . Furthermore, as can be seen from  FIG. 2 , a circumferential groove  41  is provided in the housing  4  in the region between the first and second floating ring seals  2 . In this circumferential groove  41 , the leakage supplied through the first floating ring seal  2  accumulates and forms a return flow C and further reduces the leakage occurring through the second floating ring seal to the atmosphere region  11 . 
       FIG. 3  shows a component arrangement according to a third example embodiment of the invention. As can be seen from  FIG. 3 , the floating ring seal  2  of the third example embodiment comprises a third throttling area  25 , including a first groove  23  provided between the first and second throttling areas  21 ,  22  and a second groove  26  provided between the second throttling area  22  and the third throttling area  25 . As in the first example embodiment, the first groove  23  and the second groove  26  are designed to be completely circumferential. This provides a one-piece body  20  comprising three throttling areas, thus further reducing leakage from the product region  10  to the atmosphere region  11 . 
     LIST OF REFERENCE NUMBERS 
     
         
           1  component arrangement 
           2  floating ring seal 
           3  shaft 
           4  housing 
           5  recess 
           6  sealing ring carrier 
           7  locking mechanism 
           8  first throttling gap 
           9  second throttling gap 
           10  product region 
           11  atmosphere region 
           20  one-piece body 
           21  first throttling area 
           22  second throttling area 
           23  first groove 
           24  projection 
           25  third throttling area 
           26  second groove 
           40  projection 
           41  groove 
           50  lateral notch 
           70  bolt 
           71  head 
         A double arrow 
         B 1  first width 
         B 2  second width 
         C return flow 
         N 1  groove width of the first groove  23   
         X-X Axial direction