Abstract:
The present invention regards a sealing arrangement for a valve, comprising a valve element ( 3 ) provided with a sealing element ( 4 ), arranged to be abutting a valve seat ( 2 ) in a closed state of the valve. The valve element ( 3 ) comprises at least two parts, a first and second part ( 31,32 ), each comprising an abutting surface ( 310,320 ), which abutting surfaces ( 310,320 ) are arranged facing each other and to abut against corresponding sealing element surfaces ( 41,42 ) of the sealing element ( 4 ), and whereof at least one part ( 31 ) of the valve element ( 3 ) is being arranged to be moveable relative another part ( 32 ) of the valve element ( 3 ) and the at least one part ( 31 ) of the valve element ( 3 ) comprises a pressure surface ( 311 ) exposed to a surrounding fluid in a closed state of the valve giving pressure on the sealing element ( 4 ) responsive to the pressure in the surrounding fluid.

Description:
FIELD 
     The present invention regards a sealing arrangement for a down hole valve. 
     BACKGROUND 
     In a well there are several fluid paths which need to be closed and opened depending on the activities in the well. There may be high temperatures and pressures, abrasive fluids, etc within a well which can make a safe operation of a valve difficult. In addition there may be temperature and pressure variations in the well and a valve should be safely operable within a given range of both temperatures and pressures, thereby giving that the sealing arrangement in connection with such a valve must withstand these variations and still provide a closed valve. 
     SUMMARY OF INVENTION 
     An aim with the present invention is to provide a sealing arrangement which provide a closed valve for a relative large pressure range, and this is achieved with a sealing arrangement as defined in the claims. 
     The present invention regards a valve sealing arrangement. The valve comprises a valve element provided with a sealing element, where the sealing element is arranged to be abutting a valve seat of the valve in a closed state of the valve. The closed valve closes off a fluid path, while the fluid path is open and allows the passage of fluid in an open state of the valve. 
     According to the invention the valve element comprises at least two valve element parts, a first part and a second part. The first part of the valve element is arranged moveable relative the second part of the valve element. Both the first and the second part comprises an abutting surface, which abutting surfaces are arranged facing each other and to abut against corresponding sealing element surfaces of the sealing element. The first part of the valve element comprises in addition a pressure surface exposed to a surrounding fluid in a closed state of the valve thereby transferring pressure from the surrounding fluid through the first part to the sealing element. The surrounding fluid is the fluid for which the valve is closing the fluid path. The first part is, when the valve is moved from an open state to a closed state, moved relative the second part such that the abutting surfaces are moved towards each other. This movement of the first part will give a pressure in the sealing element which is positioned between the abutting surfaces. In a closed state of the valve the first part is moved so that the abutting surfaces are in an initial relative position defined by the configuration of the valve element and the valve seat, thereby giving an initial pressure within the sealing element. The first part is in the closed state of the valve also movable relative the second part so that the abutting surfaces may be moved further towards each other, thereby increasing the pressure within the sealing element. This further movement of the first part will depend on the pressure of the fluid on the pressure surface of the first part in relation to the sealing pressure in the sealing element. 
     By such an arrangement there is provided a sealing arrangement in the valve which is pressure sensitive in relation to the fluid surrounding the valve, in that an increase in pressure in the fluid will possibly increase the sealing pressure in the sealing element, if this exceed the initial pressure in the sealing element. This because the first part of the valve element, comprising the pressure surface is arranged movable relative the second part and the sealing element is arranged between the first and the second part, a movement of the first part due to an increase in pressure will give an increased pressure from the first part to the sealing element and thereby an increased sealing pressure in the sealing arrangement. The sealing arrangement is by this safely operable for a range of pressures in the fluid for which the valve is closing the fluid path. 
     According to one aspect of the invention the pressure surface of the first part may have a larger area exposed to the fluid pressure than an area of the abutting surface in contact with the sealing element seen along one axis. This will give that a pressure increase in the fluid is increased by the difference in the areas of the pressure surface divided by the abutting surface, towards the sealing element. The result of this is that the pressure within the sealing element will always be larger than the pressure in the fluid, thereby providing a good sealing of the fluid path for a range of fluid pressures. 
     According to another aspect the valve seat may be exposed to fluid flowing through the valve in an open state of the valve. 
     According to another aspect the abutting surfaces of the two parts of the valve element may be formed as angular abutting surfaces in relation to a central axis. The abutting surfaces may in a cross section form a partly V-shape. According to one embodiment the open end of the V-shape may be facing away from the valve seat. Such an arrangement will form a dove tail groove configuration between the first part and second part of the valve element. In another embodiment it is possible that the open end of the V-shape is facing the valve seat. 
     According to another aspect the second part of the valve element may comprise a guiding part in abutment with a gliding surface of the first part of the valve element allowing relative movement between the parts. These, guiding part and gliding surface, may comprise means for keeping the parts together but allowing them to move relative each other in one direction, as for instance T-shaped tongue and grooves. 
     According to another aspect the first part of the valve element may comprise a stopping surface for abutment against a stopping seat of an element forming the valve seat. The abutment between the stopping seat and stopping surface will prevent further movement of the first part in one direction. When the valve element is in an open state of the valve the stopping surface and the stopping seat are arranged in distance from each other. When the valve element is moved to a closed state of the valve the stopping surface comes in abutment against the stopping seat and the first part is moved so that the abutting surfaces of the first and second part are moved towards each other, thereby creating a pressure within the sealing element. When the valve is in a closed state there will be an initial pressure in the sealing element, as the first part is pressured towards the sealing element by the interaction between the stopping surface and the stopping seat and the second part is pressed towards the sealing element from the opposite side by the movement of the valve element from an open to a closed position. 
     According to another aspect of the invention the second part of the valve element may comprise a protective section. This protective section is arranged upstream of the first part in a normal flow direction through the valve. This protective section is configured to cover at least a part of the pressure surface of the first part from the flow of fluid through the valve in an open state of the valve. The protective section is also configured to allow fluid to act on the pressure surface in a closed state of the valve. Such a protective section will prevent the activation of the sealing element in an open state of the valve, due to the flow of fluid through the valve. A flowing fluid will due to its velocity give a pressure on a pressure surface when the fluid flow hits a surface in addition to the pressure within the fluid. By having the protective section one is preventing the fluid flow from having such a large influence on the pressure surface that the sealing arrangement is partly activated and thereby moves the first part towards the sealing in an open state of the valve. 
     According to an aspect the sealing element is an annular shaped sealing element. The annular shaped sealing element may be mainly circular, elliptic, polygonal etc The annular shaped sealing element may be formed with a mainly triangular cross section, polygonal cross section or other form in a non-stressed formed. The cross section if the sealing element may change when the valve is moved from an open state to a closed state. 
     According to an aspect the valve seat is formed by a sleeve element. In one embodiment the valve element may also be formed as a sleeve element, in another embodiment the valve element may be formed by a plug element, within a sleeve element forming the valve seat. In one embodiment the sealing element in a closed state of the valve is pressed against the valve seat arranged radially outwards of the sealing element. In another embodiment the sealing element in a closed state of the valve is pressed against the valve seat arranged radially within the sealing element. In these last embodiments the valve element may be moved axially to move the valve between an open state and a closed state. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will now be explained with reference to the accompanying drawings where; 
         FIG. 1  shows a first embodiment of a valve with a sealing arrangement according to the invention in an open state of the valve 
         FIG. 2  shows the embodiment of  FIG. 1  in a closed state of the valve, 
         FIG. 3  shows a principle sketch of a part of a second embodiment in an open state of the valve 
         FIG. 4  shows the embodiment in  FIG. 3  in a closed state 
         FIG. 5  shows a third embodiment of a valve with a sealing arrangement according to the invention in a closed state of the valve. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1 and 2  there is shown a first embodiment of a down hole sleeve valve  1 , having a valve element  3  provided with a sealing element  4 . The valve element is shown in an open state of the valve in  FIG. 1  and a closed state of the valve in  FIG. 2 . The sealing element  4  is in a closed state of the valve arranged butting against a valve seat  2 , providing a closed fluid path in a closed state of the valve. The valve element  3  is in the embodiment shown formed by a sleeve-like element. The valve seat is in this embodiment also formed by a sleeve element. The valve element is moved in an axial direction for movement between an open state and a closed state. The valve seat  2  is formed by an inner surface of an outer sleeve element  2   a  facing in an inward radial direction. 
     The valve element  3  comprises a first part  31  and a second part  32 . The second part  32  is in this embodiment formed like a sleeve element. The first element  31  is formed as a ring element and arranged around on the outside of the second part  32 , connected to the second part  32  but arranged movable in an axial direction of the second part  32 . The first part  31  has an inner surface, a gliding surface  313 , which is abutting a guiding part  322  of the second part  32 . The first part is arranged to be movable along the guiding part  322  of the second part  32 . In an end of the guiding part  322  the second part  32  comprises an abutting surface  320 . The abutting surface is extending in a mainly radial direction. This abutting surface  320  is facing an abutting surface  310  of the first part. The sealing element  4  is arranged between these abutting surfaces  320 ,  310  of the second and first part respectively. The abutting surfaces are angled so that they in a cross section as shown in the figures gives a partly V-shape. The open end of the V-shape is facing the valve seat  2 . The sealing element  4  is an annular sealing element. An inner surface  43  of the sealing element  4  is abutting the guiding part  322  of the second element  32 , and an outer surface  44  of the sealing element will in a closed state of the valve, be abutting the valve seat  2 . Two opposite surfaces connecting the inner and outer surfaces  43 , 44 , forms a first sealing element surface  41  and a second sealing element surface  42 . These surfaces are interacting with the abutting surfaces of the first part  31  and second part  32 . 
     The first part  31  comprises a pressure surface  311  formed by the surface of the first part  31  facing in an opposite direction of the abutting surface  310 . The pressure surface will be exposed to the fluid and the pressure in the fluid when the valve is in a closed state. 
     In an open state of the valve, as shown in  FIG. 1  a biasing spring  5  is compressed, and there is a passage through the valve as indicated by the arrows in the figure. In a closed state the spring  5  is extended and the valve element is moved in an axial direction, thereby moving the sealing element towards the valve seat  2 . During this movement a stopping surface  312  of the first part  31  comes in abutment against a stopping seat  21  formed by the same element forming the valve seat  2 , and in the embodiment shown arranged at an end of the valve seat  2 . This interaction between the stopping seat  21  and the stopping surface will prevent the first element  31  from moving further in this one direction. The spring will then try to press the second part  32  of the valve element towards the first part  31 , and since these are arranged movable relative each other, this will press the sealing element  4  in between the two abutting surfaces  310  and  320 , and thereby providing a sealing pressure in the sealing element  4 . The sealing element  4  will also be pressed against the valve seat  2  with this sealing pressure. In this closed state of the valve the relative configuration of the first part, the second part, the valve seat, the stopping seat and the stopping surface in addition to the closing force of the valve element, will give a given sealing pressure in the sealing element  4 . In addition to this sealing pressure the first part  31  is arranged movable relative the second part  32 , and if the pressure of the fluid acting on the pressure surface  311  exceeds the initial sealing pressure, this pressure will further move the first part  31  towards the second part  32  in a closed state of the valve. This movement will give an increase in the sealing pressure in the sealing element  4 , thereby securing a good sealing effect for a range of pressures in the fluid. 
     The valve element may also be provided with a stopper element  321 , formed as a part of the second part  32  of attached to the second part  32 , which stopper element  31  interact with a part of the element forming the valve seat  2  and preventing the second part  32  from moving further in along the valve seat  2  in a closed state of the valve. 
     In another embodiment of the sealing arrangement, as shown with a principle sketch in  FIGS. 3 and 4 . The first part  31  has the similar features as in the first embodiment, indicated with the same reference numerals, with a pressure surface  311 , exposed to the fluid, and an abutting surface  310  abutting the sealing element  4 . The area of the pressure surface  311  is in this embodiment made larger than the area of the abutting surface  312 . This gives that with an increase in the pressure in the fluid acting on the pressure surface  311  there will be an increase in the sealing pressure in the sealing element  4  which is the fluid pressure increase multiplied with the factor of the area of the pressure surface  311  seen in one direction divided with the area of the abutting surface  312  see in the same direction, thereby ensuring a higher sealing pressure in the sealing element  4  than the pressure in the fluid. By seen in one direction it should be understood as projection of the surface into one plane. This feature may be used in all the embodiments explained. Another feature not shown in the first embodiment, but which could be incorporated in the first embodiment, is the feature of the second part  32  having a protecting part  323 . The protecting part  323  is arranged upstream of the first part  31 , in a normal flow direction through the valve. The protecting part  323  will in an open state of the valve cover at least a part of the pressure surface  311  of the first part  31 , from the flow of fluid through the valve. The protective part  323  will at least partly prevent the flowing fluid through the valve from hitting the first part  31 . In the shown embodiment the protective part  323  is formed as a flange extending in a radial direction and arranged at an end of the guiding part  322  of the second part. The abutting surface  320  is arranged at the opposite end of the guiding part  322 , seen in a axial direction of the second part  32 . This protective part  323  will be positioned close to the pressure surface  311  in an open state of the valve, but be moved away from the pressure surface  311  in a closed state of the valve, as the first part  31  is moved relative the second part  32 . The first part  31  is in this embodiment formed with the stopping surface arranged at an end of at least one rod like part of the first element  31 . The rod like part extend through the protective part  323 . The stopping surface  312  at the end of the rod like part will interact with the stopping seat  21  and move the first part relative to the second part  32 , before the flange shape protective part comes in contact with the stopping seat  21 . The configuration of the valve element is favorably so that the protective part  323  never abuts the stopping seat  21 . 
     In the embodiment shown in  FIG. 5  the configuration of the elements are mainly similar to the second embodiment, with the first and second part  31 , 32 , the stopping surface  312  and stopping seat  21  and protective part  323 , while the protective part  323  is formed as radially extending finger elements arranged in between rod like elements of the first part  31 . Another features which may be used in all the embodiments are the configurations of the abutting surfaces  310 , 320  of the first and second part, which form a partly V-shape. The open end of the V-shape is in this embodiment facing away from the valve seat  2 . The abutting surfaces  310 , 320  together with an outer surface of the guiding part  322  form a dove tail groove. 
     The invention has now been explained with different non-limiting embodiments. A skilled person will understand that there could be made alterations and modifications to the embodiments that are within the scope of the invention as defined in the claims. The sealing arrangement may for instance be used with a valve element in the form of a plug. The valve seat may be arranged within an outer sleeve formed valve element, the first and or second part of the valve element may comprise several elements together forming the first and or second part. The guiding part may be formed by the first element instead of the second element, the pressure surface may alternatively be formed on the second part etc.