Abstract:
A butterfly valve with a valve disk mounted to swivel about an axis of rotation inside a housing and torsionally rigidly connected to a drive shaft pivotably mounted inside the housing. To ensure a connection which, from the standpoint of production engineering, is simple, yet secure, the valve disk is torsionally rigidly connected to the drive shaft by means of a minimum of two tapered pins engaging opposite sides of the drive shaft.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a butterfly valve. 
       BACKGROUND 
       [0002]    Butterfly valves are shutoff elements widely used in water resources engineering. In contrast to slide gate valves, butterfly valves are extremely compact and, especially in nominal widths larger than DN 300, require considerably less mounting space. Therefore, piping systems with nominal widths from approximately DN 300 are most often equipped with butterfly valves. Butterfly valves generally comprise a valve disk, which is mounted to swivel about an axis of rotation inside a housing and which is torsionally rigidly connected to a drive shaft that is pivotably mounted inside the housing. In the prior art valve disks, the drive shaft is often connected to the valve disk by means of splined shaft couplings or polygon couplings. Although this ensures a secure connection with good force transmission, the manufacture of shaft/hub couplings of this type is complex and, accordingly, entails high costs. 
         [0003]    U.S. 2012/0248361 A1 discloses a prior art butterfly valve comprising a valve disk swivel mounted about an axis of rotation inside a housing, and having a disk-shaped valve body and hubs for receiving a drive shaft, which is pivotably mounted inside the housing; and a bearing bolt on the opposite side of the drive shaft. In this prior art butterfly valve, both the drive shaft and the bearing bolt are torsionally rigidly connected to the valve disk by means of a tapered pin. 
       SUMMARY OF THE INVENTION 
       [0004]    In some embodiments, a butterfly valve according to the disclosure makes it possible to connect the drive shaft and the valve disk in a manner that is simple from the standpoint of production technology, yet secure at the same time. 
         [0005]    Useful embodiments and advantageous variations of the invention are also disclosed. 
         [0006]    In the butterfly valve according to the present invention, the valve disk is torsionally rigidly connected to the drive shaft by means of a minimum of two tapered pins, which engage opposite sides of the drive shaft, with the two oppositely lying tapered pins being disposed on the valve disk. Owing to the tapered pins, it is possible, with simple means, to create an easy-to-install, yet torsion- and blowout-proof connection between the valve disk and the drive shaft. The connection by means of the tapered pins is especially easy to install, since it obviates the need for drilling bores when the valve is assembled, and since the tapered pins allow relatively large tolerances. Using the tapered pins makes it possible to achieve a zero-backlash connection in a simple manner, and settings and adjustments are easy to make as well. Furthermore, since, by means of the tapered pins, the drive shaft is also axially securely held on the valve disk, a blowout-proof connection is ensured. 
         [0007]    In an embodiment that is especially advantageous from the standpoint of production engineering, the tapered pins can be configured as cylindrical pins with a sloping wedge face complementary to an inclined chamfer of the drive shaft. Such tapered pins are easy to produce and easy to install. Furthermore, the wedge faces and the complementary chamfers on the drive shaft provide good force transmission, thereby reducing the load on the drive shaft, the valve disk and the pins to a minimum. Instead of cylindrical pins with a sloping wedge face, the tapered pins could also be configured as conical pins. 
         [0008]    According to a useful embodiment, the tapered pins can be disposed in bores that extend tangentially with respect to a receiving opening for the drive shaft through a hub of a valve body of the valve disk and which intersect the receiving opening. 
         [0009]    The bores for the tapered pins can preferably be configured as blind bores and, starting from a back side of the valve body and extending to the top side of the hub, run at right angles with respect to the axis of rotation of the valve disk. However, the bores for the tapered pins can also be configured as through-bores. Instead of being disposed at right angles with respect to the valve disk, the bores can, however, also extend in the direction of the valve disk. 
         [0010]    The valve disk may have only two tapered pins, one lying opposite to the other. However, it is also possible to use more than two tapered pins, which can also be offset with respect to one another in the direction of the axis of rotation. 
         [0011]    The bores preferably have internal threads, into which threaded pins with complementary external threads are inserted above the tapered pins. The tapered pins can be inserted and axially secured by means of the threaded pins. 
         [0012]    It is also possible to insert additional plugs into the bores above the threaded pins. In this manner, fluid can be prevented from penetrating into the bores and, thus, potential corrosion caused thereby can be avoided. In addition, toward the top, the bores are preferably covered by a retaining ring that is attached to the valve body by means of screws. Owing to the retaining ring, which is also used to retain the gasket, the pin connection is protected against corrosion and cannot be seen from the outside. However, the bores for the tapered pins need not necessarily be disposed under the retaining ring. At larger nominal widths, the bores can also be disposed so as to be inwardly offset with respect to the retaining ring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Other special features and advantages of the invention follow from the description of preferred practical examples below based on the drawing. The figures show: 
           [0014]      FIG. 1  a butterfly valve with a housing and a valve disk in a partially sectional perspective view; 
           [0015]      FIG. 2  a valve body of the valve disk shown in  FIG. 1  in a sectional view along the axis of rotation; 
           [0016]      FIG. 3  an enlarged detail view of the area of connection between the valve disk and a drive shaft; and, 
           [0017]      FIG. 4  a longitudinal section of a tapered pin. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The butterfly valve schematically represented in  FIG. 1  comprises a housing  2  with a round through-opening  1  in which a valve disk  3  is mounted to swivel about an axis of rotation  4  perpendicular with respect to the central axis of the through-opening  1 . The ring-shaped housing  2  has anterior and posterior connecting flanges  5  and  6 , respectively, so as to be able to connect it to a piping system. In addition, the housing  2  also comprises two oppositely lying mounting flanges  8  in which the valve disk  3  is pivotably mounted by means of a drive shaft  10  and a bearing bolt  9  via bearing bushings  11 . 
         [0019]    In the embodiment shown, the valve disk  3  is configured to rotate eccentrically and has a disk-shaped valve body  12 , which is offset with respect to the axis of rotation  4 , and two hubs  14  disposed opposite to each other and projecting beyond a front side  13  of the valve body  12 . In addition, the valve disk  3  comprises a ring- or disk-shaped gasket  15  and a retaining ring  18  releasably mounted by means of screws  17  to a back surface  16  of the valve body  12  and by means of which retaining ring the gasket  15  is attached to the valve body  12 . The connection between the valve body  12  of the valve disk  3  and the drive shaft  10  is implemented by means of tapered pins  19 , which will be explained in greater detail below. 
         [0020]    As  FIG. 2  indicates, the hubs  14  projecting beyond the front side  13  of the valve body  12  have convex inside surfaces  20  that face each other. In the embodiment shown, the hubs  14  have an elliptical or bi-convex cross section and, in addition to the convex inside surfaces  20  that face each other, they also have convex outside surfaces  21 . 
         [0021]    On the front side  13  of the valve body  12 , two cavities  22  arcuately extending along the two inside surfaces  20  of the hubs  14  are disposed so as to be able to divert the flow around the hubs  14 . The two groove-like cavities  22 , which have U-shaped cross sections, are separated from each other by a convexly curved middle bridge-like section  23 , which widens on both sides from the middle of the valve body  12  toward the outer sides. Owing to the two arcuately extending cavities  22 , flow channels are formed between the two hubs  14 , which flow channels divert the flow around the hubs  14 . Disposed in the middle bridge-like section  23  are two diametrically oppositely lying recesses  24  which, when seen in plan view, are V-shaped and which extend from the edge of the valve body  12  toward the middle thereof. As a result, when seen in plan view, the contour between the two hubs  14  on the front side of the valve body  12  has the shape of an X. This contour contributes to optimizing the flow and provides reinforcement. 
         [0022]    As seen in  FIG. 2 , the back side  16  of the valve body  12  also has a special contour with arcuate ribs  25 , a depression  26  disposed between the ribs  25 , and recesses  27  disposed on the back between the ribs  25  and the outer side of the valve body  12 . On the front side  13 , the ribs  25  are disposed opposite to the cavities  22 , while the depression  26  is located opposite to the middle bridge-like section  23  disposed on the front side  13 . The width of the depression  26  expands beginning in the middle and extending toward both sides. As a result, the valve body  12 , in a cross section extending along the axis of rotation  4  through the two hubs  14 , comprises a W-shaped cross-sectional area as can be seen in  FIG. 2 . To be able to receive the gasket  15  and the retaining ring  18 , the valve body  12 , on its back side  16 , has a stepped cavity with a ring-shaped inside support area  28  for the retaining ring  18 . 
         [0023]    Disposed in the two hubs  14  are lateral openings  29  and  30  for receiving the drive shaft  10  shown in  FIG. 1  and the bearing bolt  9  located on the opposite side of the drive shaft  10 . Disposed in the hub  14  with the opening  29  for the drive shaft  10  are bores  31 , which extend tangentially with respect to the opening  29 , for two tapered pins  19  disposed on opposite sides of the drive shaft  10  so as to torsionally rigidly connect the drive shaft  10  to the valve body  12 . As seen in  FIG. 2 , the bores  31  for the tapered pins  19  are disposed in the hub  14  at right angles with respect to the axis of rotation  4  in such a manner that they partially intersect with the opening  29 , thereby allowing the outside of the drive shaft  10 , when inserted into the opening  29 , to project on two oppositely lying points into the bores  31 . 
         [0024]    As  FIG. 3  indicates, starting from the back side  16  of the valve body  12  and extending to the top side of the hubs  14 , the bores  31  are configured as blind bores running at right angles with respect to the axis of rotation  4  of the valve disk  3 . The tapered pins  19  disposed in the bores  31  have sloping wedge faces  32  complementary to two inclined chamfers  33  on opposite sides of the drive shaft  10 . The bores  31  are here disposed so as to lie opposite to each other and have internal threads  34  into which threaded pins  37 , with complementary external threads  35 , and hexagonal recesses  36  are inserted. Using the threaded pins  37  inserted above the tapered pins  19 , the tapered pins  19  can be axially secured. In addition, above the threaded pins  37 , plugs  38 , made of rubber or the like, are inserted into the bores  31 . In this manner, fluid can be prevented from penetrating into the bores and, thus, potential corrosion caused thereby can be avoided. In addition, toward the tops, the bores  31  are preferably covered by a retaining ring  18  attached to the valve body  12  by means of screws  17 . Thus, the pin connection is protected against corrosion and cannot be seen from the outside. The hubs  14  can have holes  39  so as to be able to divert the flow. 
         [0025]    The tapered pins  19  separately shown in a longitudinal section in  FIG. 4  are configured as cylindrical pins with an internal thread  40 . Thus, the tapered pins  19  are easy to manufacture and, if required, can be easily removed.