Abstract:
A rotary gate valve includes first and second opposing housing members having coaxial pathways and defining a gate channel when joined together. A gate is positioned within the gate channel when the valve is in a closed position to prevent media from flowing through the pathways and rotationally displaced from the channel when the valve is in an open position to allow media to flow through the pathways. First and second annular primary sealing sleeves are disposed within the first and second housing members and are adapted to sealingly engage each other when the valve is in the open position, and with the gate valve when the valve is in the closed position. A secondary sealing member is disposed around an upper portion of the gate and secured between the housing members above the first and second annular primary sealing sleeves to prevent process media from entering the housing members.

Description:
CROSS-REFERENCE 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/961,846, filed Dec. 20, 2007, which is expressly incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of flow control valves and the construction thereof. More specifically, the present invention relates to a rotary gate valve that provides faster operation and occupies less vertical space within a process pipeline. 
     Flow control valves such as, for example, knife gate valves or line blind valves, are used to control the flow of process media and can be particularly well suited for use with abrasive and corrosive slurries used in, for example, the mining, pulp or paper industries. One form of gate valve known in the art includes a housing and passageway therethrough. On opposite sides of the housing are connections for installing the valve in a pipe line, for example, the housing can be bolted to a flange end of a pipe. To control the flow of fluid through the valve, the valve includes a knife gate that is disposed within the valve body. In operation, when the knife gate is raised vertically, the valve is open and process media flows through the passageway. When the knife gate is lowered vertically, the valve is closed and process media is prevented from flowing through the passageway. Because typical knife gate valves operate vertically, actuators must be mounted on top of the gate valve. This requires significant space above the valve for the actuator and valve package in an already crowded process pipeline environment. Thus, there is a need for a gate valve that operates quicker than existing gate valves while reducing valve package vertical space requirements. 
     SUMMARY OF THE INVENTION 
     Preferred embodiments of the inventions are directed to a rotary gate valve comprising a first and second opposing housing members each having coaxial pathways and defining a gate channel when the housing members are joined together. A gate is positioned within the gate channel when the valve is in a closed position to prevent media from flowing through the pathways and rotationally displaced from the channel when the valve is in an open position to allow media to flow through the pathways. A first annular primary sealing sleeve is disposed within the first housing member and a second annular primary sealing sleeve is disposed within the second housing member. Each of the first and second annular primary sealing sleeves is adapted to sealingly engage each other under compression when the valve is in the open position, and with the gate when the valve is in the closed position. A secondary sealing member is disposed around an upper portion of the gate and secured between the housing members above the first and second annular primary sealing sleeves. The secondary sealing member has an aperture extending therethrough and an inner peripheral wall around the aperture adapted to sealingly engage the upper portion of the gate. The secondary sealing member is configured to prevent process media from entering the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a rotary gate valve in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 2  illustrates an exploded view of the rotary gate valve shown in  FIG. 1  in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 3  is a side view of an exemplary rotary gate valve in an open position in accordance with an exemplary alternative embodiment of the present disclosure. 
         FIG. 4  is an exploded view of the rotary gate valve shown in  FIG. 3  in accordance with an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a perspective view of an embodiment of a rotary gate valve in axial alignment within a pipeline in accordance with the present invention. Valve  10  generally includes valve housing  15  defining a pathway or channel  20  having an inlet and outlet through which process media flows along a flow axis. Valve  10  is connected to a process pipeline via flange assemblies and housing  15 . Valve shaft assembly  30  located at an upper portion of housing  15  allows a valve gate to swing open to allow process flow through valve  10  and swing closed to prevent process flow through valve  10 . Gate guard  25  is connected to housing  15  via fasteners  26  and is used to protect the gate from external exposure. An actuator may be connected to valve shaft assembly  30  to open and close the gate. Various types of actuators may be used including pneumatic, hydraulic and electric to open and close valve  10 . An actuator and valve package, including for example, a manifold can be mounted parallel to the flow axis to avoid vertical component stacking. 
       FIG. 2  is an exploded view of the rotary gate valve  10  shown in  FIG. 1 . Gate  40  has a substantially teardrop shape with a curved lower portion  41  and shaft aperture  42 . Gate  40  is positioned within housing channel  21 . When valve  10  is in a closed position, gate  40  completely covers pathway  20 . Washers  43  are disposed between gate  40  and housing  15  to prevent gate  40  from rubbing and galling. Lubrication may be supplied to gate  40  via grease fitting  48  and corresponding channel  49 . Gate guard  25  is attached to housing  15  via fasteners  25   a  and  25   b . Guard  25  may be made from, for example, sheet metal or other material sufficient to protect gate  40  from environmental conditions as well as protecting users from external contact with the gate when valve  10  is in an open position. 
     Gate valve  10  includes shaft assembly  30  located at an upper portion of housing  15 . Shaft assembly includes shaft  31 , bushings  32  and  33 , actuator key  34 , actuator spacer  35  and housing flange  36 . Shaft  31  is positioned within bushing  32  through shaft orifice  37  along axis A-A which is above and parallel with the flow axis of pathway  20 . Shaft  31  has a first round end  31   a  connected to bushing  33  and a rectangular portion  31   b  which engages shaft aperture  42  of gate  40 . Although portion  31   b  is shown have a rectangular shape, alternative configurations may be used to provide engagement with shaft aperture  42 . As shaft  31  rotates in counterclockwise direction (CC) upon actuation, rectangular portion  31   b  engages shaft aperture  42  and applies the rotational force of shaft  31  to gate  40  in direction CC. This counterclockwise movement forces gate  40  outside the axis of valve housing  15  into an open position where gate  40  is completely withdrawn from the process flow. Gate guard  25  surrounds gate  30  when valve  10  is in this open position. Likewise, as shaft  31  rotates in a clockwise direction (C) upon actuation, rectangular portion  31   b  applies the rotational force of shaft  31  to gate  40  via shaft aperture  42  to rotate gate  40  in direction C. This clockwise C movement of gate  40  returns the gate inside valve housing  15  via channel  21  to close the valve. Because of its rotational configuration, gate  40  only has to travel approximately ¼ turn to go from a closed position to an open position. 
     Housing spacer  36  includes a ridge portion  36   a  which receives rim  32   a  of bushing  32 . Bushing  32  receives shaft  31  and actuator key  34  is received by channel  31   c  of shaft  31 . Actuator spacer  35  is connected to housing spacer  36  and receives an external actuator used to open and close valve  10 . Bore  15   a  extends through each side of housing  15  and is aligned with lockout hole  40   a  of gate  40 . When gate  40  is in an open position, lockout pin  50  may be inserted through bore  15   a  and hole  40   a  to prevent gate  40  from closing. This lockout function may be used in addition to actuator control. 
     Valve  10  also includes a pair of sleeves  55   a  and  55   b  having an inner diameter corresponding to the size of channel  20 . Sleeves  55   a  and  55   b  are compressed into housing  15 . Because a pair of sleeves is used, the downstream sleeve (either sleeve  55   a  or  55   b  depending on the installation configuration) can be replaced when gate  40  is in a closed position while the upstream sleeve still holds pressure. Sleeves  55   a  and  55   b  may be made from, for example, rubber, EPDM, CSM or other similar type material depending on the type of process application. Each of sleeves  55   a  and  55   b  include flange portions  56  and body portion  57 . Body portions  57  fit within housing  15  and flange portions  57  fit around pathway  20 . Sleeves  55   a  and  55   b  create a seal on each side of gate  40  when in a closed position and prevent leakage when gate  40  is in an open position. Retainer flanges (not shown) are disposed between each sleeve  55   a  and  55   b  and the process pipeline. These flanges retain sleeves  55   a  and  55   b  in position relative to valve housing  15 . 
       FIG. 3  illustrates an exemplary rotary gate valve  100  according to an alternative embodiment of the present disclosure in an open position. Valve  100  generally includes valve housing  115  defining a pathway or channel  120  having an inlet and outlet through which process media flows along a flow axis. Valve housing  115  may be formed from a pair of opposing housing halves having coaxial channels within which a rotary gate  140  is disposed. Valve  100  is connected to a process pipeline via flange assemblies and housing  115 . A valve shaft assembly  130  provides a pivot point for rotary gate  140  which allows the gate to swing open to allow process flow through valve  100  and swing closed to prevent process flow through valve  100 . A gate guard  145  is connected to housing  115  via fasteners  126  and is used to protect the gate from external exposure. An actuator adapter assembly  150  may be connected to valve  100  to allow an actuator to be coupled to valve  100  to open and close the rotary gate  140  via shaft assembly  130 . Various types of actuators may be used including pneumatic, hydraulic, electric, manual, etc. 
     A primary seal between the rotary gate  140  and the housing  115  is formed by a pair of sleeves. A first of the pair of sleeves  155   a  is shown in  FIG. 3  and a mirror image of this sleeve is disposed at the other opening of channel  120  similar to sleeves  55   a  and  55   b  described above with reference to  FIG. 2 . Each of the pair of sleeves has an inner diameter corresponding to the size of channel  120 . Each of sleeves include flange portions (e.g.  156 ) and body portion  57 . Body portions  157  fit within housing  115  and flange portions  156  fit around pathway  120  to create a seal between valve  100  and a process pipeline attached to the upstream and downstream sides of the valve. The sleeves form a gate channel through which rotary gate  140  travels. In addition, the sleeves create a seal on each side of gate  140  when valve  100  is in a closed position and prevent leakage when gate  140  is in an open position. Because a pair of sleeves is used, the downstream sleeve can be replaced when gate  40  is in a closed position while the upstream sleeve still holds pressure. Sleeves  55   a  and  55   b  may be made from, for example, rubber, EPDM, CSM or other similar type material depending on the type of process application. 
     The valve  100  includes a secondary sealing member  160  disposed between the first and second housing halves and surrounding the upper portion  140   a  of gate  140 . Secondary sealing member  160  is configured to prevent process media leakage into housing  115  and actuator adapter assembly  150 . Referring to  FIG. 4  which is an exploded view of valve  100  with gate  140  shown as removed from the valve housing, the secondary sealing member  160  is disposed within slot  161  located above gate shaft  146  of housing  115 . More particularly, secondary sealing member  160  is disposed within shaft assembly  130 . Secondary sealing member  160  may be, for example, a unitary molded elastomeric material such as natural rubber or other suitable synthetic elastomer such as polyurethane, etc. Secondary sealing member  160  includes an inner peripheral wall  160   a  which defines an aperture  160   b . This inner peripheral wall surrounds the upper portion  140   a  of gate  140 . Secondary sealing member  160  is secured to housing  115  by actuator adapter assembly  150  and associated fasteners  151 . While the primary sleeves prevent direct slurry line pressure on the secondary sealing member  160 , the secondary sealing member  160  is itself capable of withstanding process media spray during actuation of gate  140 . Secondary sealing member  160  replaces standard packing material around the upper portion of gate  140  to prevent leakage and to wipe excess process media from gate  140  as the gate moves between open and closed positions. Thus, there is no need for constant manual adjustment of secondary seal  160  such as in the case of conventional packing in order to stop valve leakage. 
     As mentioned above, an actuator may be mounted to actuator adapter assembly  150  which is used to displace gate  140  within housing  115 . In particular, actuator adapter assembly  150  is configured to allow an actuator to engage the upper portion  140   a  of gate  140 . The actuator may be configured to move in a linear direction thereby displacing the upper portion  140   a  of gate  140  perpendicular to the flow path and causing the gate to move in a clockwise or counterclockwise direction thereby closing and opening the valve. This counterclockwise movement forces gate  140  outside the axis of valve housing  115  into an open position where gate  140  is withdrawn from the process flow. Gate guard  145  surrounds gate  140  when valve  100  is in this open position. Likewise, as the upper portion  140   a  of gate  140  is displaced in the opposite direction by actuation, gate  140  rotates in a clockwise direction which returns the gate inside valve housing  115  to close the valve. Because of its rotational configuration, gate  140  only has to travel approximately ¼ turn to go from a closed position to an open position, thereby reducing actuation times. 
     While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.