Patent Publication Number: US-9845887-B2

Title: Slide ring seal

Description:
TECHNICAL FIELD 
     The invention relates to a slide ring seal. 
     RELATED ART 
     Slide ring seals developed as running gear seals are in particular often used for the sealing of drives, as well as propulsion or downthrust for low peripheral speeds of up to approx. 10 m/s, while ensuring a static seal to the air side. The slide and/or counter rings of running gear seals are made of hard and wear-resistant metallic materials (stellite, steel, duronit, and similar materials). 
     DE 101 55 653 C2 discloses a slide ring seal, in particular a running gear seal, comprising an angular slide ring and counter ring, which form a sealing surface with their radial seal legs, and seal bodies made of elastomeric material, which are positioned between the housing containing the slide ring seal and the radial external surface of the axial legs of the slide and counter ring. 
     DE 10 2004 036 974 describes a slide ring seal, in particular a running gear seal, described, including a counter ring and a slide ring, each with a sliding surface to accommodate an elastomer spring element, a housing assigned to the counter ring and slide ring with a counter running surface for the spring element, with the housings being connected concentrically to form a unit and an anti-twist protection device being provided in the area of the counter ring and slide ring. 
     As a result of EP 0 779 457 A1, a slide ring seal is already known, which consists of a slide ring and/or counter ring made of metallic material with a tapered surrounding surface intended to receive an elastic rolling element. The outside surface of the slide ring and/or counter ring that is turned to the medium is coated with a baked on powder coating. 
     DE 31 41 512 A1 shows a slide ring and/or a counter ring with a slide ring seal. This slide ring seal is equipped with a secondary sealing location on the medium side in the area of the slide ring and/or counter ring, which consists of an O ring and a supporting ring if necessary. 
     DE 1 928 675 describes a contact-free mechanical seal equipped with packaging. The sliding surface of one of the rings is formed in a slightly convex manner by means of a lapping process in order to create the necessary wedge-shaped space on the outer radial areas of the sealing ring, with the separation of the areas being initiated and maintained during operation. 
     In the same way, U.S. Pat. No. 3,905,606 also shows a seal that acts without contact in which the slide ring, which can be moved axially and is secured to a housing, has a convex curved profile, the radiuses of curvature of which gradually decrease from the interior diameter to the external diameter of the ring. 
     U.S. Pat. No. 554,896 relates to a slide ring seal, in which the sealing surfaces of the slide and counter rings lie completely on top of each other and at least one of the sealing rings is made from a composite material. 
     SUMMARY OF THE INVENTION 
     The aim of the invention is to extend the technical field of application of, in particular running gear seals, so that they can also be used for peripheral speeds above 10 m/s, in particular for peripheral speeds of up to 30 m/s and are capable of replacing the current radial shaft seals, which have a significantly shorter useful life. 
     This aim is achieved in that at least the sliding surface of the slide ring is provided with a convex contour, with the convex-shaped contour being provided in the almost trapezoidal-shaped area of the sliding surface. 
     In its simplest form, the slide ring seal includes only a slide ring in operative connection with an elastomer spring element, in which the sliding surface is equipped the contour in accordance with the invention. 
     In principle, first of all, all geometric curve-shaped contours are addressed. 
     Of particular advantage is if the curvature is designed in the manner of a radius. 
     The slide ring seal in accordance with the invention can be used as a running gear seal for significantly higher peripheral speeds of up to 30 m/s and for this reason is capable of replacing the current radial shaft seals, which have a significantly shorter useful life. 
     Each contour is preferably produced by means of a polishing process or a turning operation on the sliding surface. 
     Depending on the application, it may be useful to provide the sliding surface with a low-friction coating. DLC, or PVD, or chrome are possible coatings. The technician will, depending on the application, select the appropriate type of coating. 
     A further idea in line with the invention is for the slide ring to be formed in a cross section in an approximately angular manner and to have a radially extending slide surface and a trapezoidal area running at an angle to that, with the slide surface being equipped with the convex-shaped contour in the almost trapezoidal area of the sliding surface. 
     A running gear seal often consists of a slide ring and a counter ring, with the sliding surfaces facing each other. A further idea in accordance with the invention is to equip the sliding surface of the slide ring and also the counter ring with the convex-shaped contour. It would be of particular advantage here for the contours of the sliding surface to be formed in a substantially similar manner. 
     The geometry of the running surface in accordance with the invention significantly reduces the surface pressure and in addition, there are also advantages with regard to possible misalignment problems between the sliding surface of the slide ring and the counter running surface, especially the counter running surface of the counter ring. 
    
    
     
       THE DRAWINGS 
       The subject of the invention is illustrated with an example of execution in the figures and is described as follows. The figures show: 
         FIG. 1  A cross-sectional view of a running gear seal including a slide and counter ring; 
         FIG. 2  A fragmentary view of the slide ring; 
         FIG. 3  A fragmentary view of the slide ring and counter ring; 
         FIG. 4  An enlarged fragmentary view of the sliding area between the slide ring and the counter ring; and 
         FIG. 5  A cross-sectional view of the slide ring and the contour ring. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a slide ring seal formed as a running gear seal  1 , consisting of a slide ring  2 , a counter ring  3 , and an elastomer spring element  4  for each. The cross section of slide ring  2  and counter ring  3  is approximately angular and each ring has a sliding surface  5 ,  6  and a receiving area  5 ′,  6 ′ for the spring elements  4 . 
       FIG. 2  shows a partial view of the slide ring  2 . The sliding surface  5  can be seen. In that region of the sliding surface  5 , which is marked with an arrow leader line, the sliding surface  5  is equipped with a convex-shaped contour  7 . In this example, the sliding surface  5  runs in a radial direction and runs outside the sliding surface  5  into trapezoidal surface  8 . 
       FIG. 3  shows an enlarged view of slide ring  2 , the counter ring  3 , the two sliding surfaces  5 ,  6  and the trapezoidal surfaces  8 . The sliding surface section equipped with the convex-shaped contour  7  is circled. 
       FIG. 4  shows a 50-fold enlargement in area  7  in accordance with  FIG. 3 . In this area  7 , also shown are radii r,r′, which are equal in dimension. It is further shown that only the sliding surfaces  5 ,  6  are provided with a chromium coating  9 ,  9 ′.