Valves

Abstract

A downhole valve ( 10 ) comprises a body ( 12 ) defining a through bore ( 14 ) and a valve seat ( 16, 17 ); and a valve member ( 18 ) mounted in the body and moveable between positions to open and close the body bore ( 14 ). The valve member ( 18 ) defines a segment of a wall of a hollow sphere. In the open position the valve member ( 18 ) is located to one side of the bore ( 14 ) and in the closed position the valve member ( 18 ) engages the valve seat ( 16, 17 ).

We claim:  
     
         1 . A downhole valve comprising: a body defining a through bore and a valve seat; and a valve member mounted in the body and moveable between positions to open and close the body bore, the valve member defining a portion of a surface of a sphere, in the open position the valve member being located to one side of the bore and in the closed position the valve member engaging the valve seat.  
     
     
         2 . The valve of  claim 1 , wherein the valve member defines a segment of a surface of a hollow sphere.  
     
     
         3 . The valve of  claim 1 , wherein the valve member defines a segment of a wall of a hollow sphere.  
     
     
         4 . The valve of  claim 1 , wherein at least one surface of the valve member for cooperating with a valve seat is concave.  
     
     
         5 . The valve of  claim 1 , wherein at least one surface of the valve member for cooperating with a valve seat is convex.  
     
     
         6 . The valve of  claim 1 , wherein the valve member is movable between the open and closed positions along a curved path following the surface of said sphere, such that the valve member is effectively rotated about an axis of the sphere.  
     
     
         7 . The valve of  claim 6 , wherein the effective axis of rotation of the valve member lies within the body.  
     
     
         8 . The valve of  claim 6 , wherein the body bore has a central axis and the effective axis of rotation of the valve member is spaced from said body bore central axis.  
     
     
         9 . The valve of  claim 7 , wherein the valve member is pivotally mounted to the body.  
     
     
         10 . The valve of  claim 8 , wherein the effective axis of rotation of the valve member lies outwith the body.  
     
     
         11 . The valve of  claim 10 , wherein the valve member is slidable relative to the body.  
     
     
         12 . The valve of  claim 11 , further comprising a curved track along which the valve member is movable.  
     
     
         13 . The valve of  claim 12 , further comprising means for pushing and pulling the valve member along said curved track.  
     
     
         14 . The valve of  claim 1 , wherein the valve body defines a valve member-receiving volume, adapted to be occupied by the valve member in the open position.  
     
     
         15 . The valve of  claim 14 , wherein said volume is at least partially defined by an inner wall corresponding substantially to the form of an adjacent face of the open valve member.  
     
     
         16 . The valve of  claim 15 , wherein said inner wall is adapted to provide a void between the wall and the closed valve member to accommodate debris which is carried into the volume on the valve member opening.  
     
     
         17 . The valve member of  claim 15 , wherein the valve body is relatively thick in the region of said valve receiving volume.  
     
     
         18 . The valve of  claim 1 , wherein the valve seat is movable relative to the valve member.  
     
     
         19 . The valve of  claim 18 , wherein the valve seat is adapted to be selectively urged towards the valve member, to maintain seal integrity therebetween.  
     
     
         20 . The valve of  claim 1 , wherein two valve seats are provided, one on each side of the valve member.  
     
     
         21 . The valve of  claim 20 , wherein the valve member is adapted to slide between the seats, into the closed position.  
     
     
         22 . A valve comprising: 
 a body defining a through bore and the bore having a centre line; and    a valve member mounted in the body and being moveable along a curved path between open and closed positions, the path corresponding to an arc of a circle having its centre spaced from said centre line.    
     
     
         23 . The valve of  claim 22 , wherein said curved path corresponds to an arc of a circle having its centre located outwith the body.  
     
     
         24 . The valve of  claim 21 , further comprising means for pushing and pulling the valve member along said curved path.