Fluid valve arrangement

Abstract

The invention relates to a pressure controlling valve comprising a slidable spool ( 102 ) arranged to be spring loaded towards a neutral position, wherein a first port ( 103 ) and a second port ( 104 ) are connected to allow a fluid flow through the valve. A first and a second pilot port are connected to a cavity adjacent a respective first and second end surface of the spool ( 102 ). The pilot ports ( 107, 108 ) are connected to a fluid conduit on either side of a fluid device ( 114; 501, 502; 601 ) causing a pressure drop in said fluid conduit and which fluid device ( 114; 501, 502; 601 ) is connected to one of the first or second ports. The spool ( 102 ) comprises a first and a second control surface ( 115, 116 ) located in a first and a second cavity, which are connected by a third cavity. The spool ( 102 ) is displaced against the spring load in response to a pressure difference between the first and the second pilot port, whereby the first or the second control surface is arranged to restrict the fluid flow through the valve when the first or the second control surface approaches the third cavity. The invention also relates to a valve arrangement comprising such a pressure controlling valve.

1 . A pressure controlling valve comprising a valve body ( 101 ) having a slidable spool ( 102 ) arranged to be spring loaded towards a neutral position in said valve body ( 101 ), a first port ( 103 ) and a second port ( 104 ) for a fluid, said first and second ports ( 103 ,  104 ) being connected to allow a fluid flow through the valve, a first pilot port ( 107 ) connected to a cavity adjacent a first end surface of the spool ( 102 ), and a second pilot port ( 108 ) connected to a cavity adjacent an opposite, second end surface of the spool ( 102 ), wherein said pilot ports ( 107 ,  108 ) are connected to a fluid conduit ( 105 ,  106 ) on either side of a fluid device ( 114 ;  501 ,  502 ;  601 ) causing a pressure drop in said fluid conduit ( 105 ,  106 ) and which fluid device ( 114 ;  501 ,  502 ;  601 ) is connected to one of the first or second ports, characterized in that the spool ( 102 ) comprises a first and a second control surface ( 115 ,  116 ) located in a first and a second cavity ( 117 ,  118 ), respectively, which first and second cavity has a cross-sectional area that is larger than the cross-sectional area of the spool ( 102 ); that the first and the second cavity are connected by a third cavity ( 120 ), and that the spool ( 102 ) is operable to be displaced against the spring load in response to a pressure difference exceeding a predetermined value between the first and the second pilot port ( 107 ,  108 ), whereby the first or the second control surface is arranged to restrict the fluid flow through the valve when the first or the second control surface ( 115 ,  116 ) approaches the third cavity ( 120 ). 
     
     
         2 . A pressure controlling valve according to  claim 1 , characterized in that the first control surface ( 115 ) is arranged to restrict the fluid flow through the valve in a first direction when the first control surface ( 115 ) approaches the third cavity ( 120 ), and that the second control surface ( 116 ) is arranged to restrict the fluid flow through the valve in an opposite, second direction when the second control surface ( 116 ) approaches the third cavity ( 120 ). 
     
     
         3 . A pressure controlling valve according to  claim 1  or  2 , characterized in that the first control surface ( 115 ) is arranged to prevent fluid flow through the valve in a first direction when the first control surface enters the third cavity ( 120 ), and that the second control surface ( 116 ) is arranged to prevent fluid flow through the valve in an opposite, second direction when the second control surface enters the third cavity ( 120 ). 
     
     
         4 . A pressure controlling valve according to any one of the above claims, characterized in that the first and the second control surface ( 115 ,  116 ) are arranged facing each other on opposite sides of the third cavity ( 120 ). 
     
     
         5 . A pressure controlling valve according to any one of the above claims, characterized in that the spool ( 102 ) comprises flow controlling recesses in its outer periphery, which recesses have an increasing cross-sectional area in the direction of the respective first and second control surface. 
     
     
         6 . A pressure controlling valve according to any one of the above claims, characterized in that the spool ( 102 ) is spring loaded in a first direction by a first spring ( 121 ) arranged at the first end of the spool ( 102 ) and in an opposite, second direction by a second spring ( 122 ) arranged at the second end of the spool ( 102 ). 
     
     
         7 . A pressure controlling valve according to  claim 6 , characterized in that the first and second springs ( 121 ,  122 ) are subjected to the same pre-load. 
     
     
         8 . A pressure controlling valve according to  claim 6 , characterized in that the first and second springs ( 121 ,  122 ) are subjected to different levels of pre-loading. 
     
     
         9 . A pressure controlling valve according to any one of the above  claims 1 - 5 , characterized in that the spool ( 102 ) is spring loaded by a single spring ( 221 ) attached to one end of the spool ( 102 ). 
     
     
         10 . A pressure controlling valve according to any one of the above claims, characterized in that the first and the second cavity is located remote from the respective first and second ends of spool ( 102 ). 
     
     
         11 . A pressure controlling valve according to any one of the above claims, characterized in that the third cavity has a cross-sectional area that is equal to the cross-sectional area of the spool ( 102 ), 
     
     
         12 . A pressure controlling valve according to any one of the above  claims 1 - 10 , characterized in that each of the first and the second control surfaces are arranged to cooperate with a first and a second seat facing its respective a first and a second control surface ( 115 ,  116 ), to prevent fluid flow through the valve. 
     
     
         13 . A fluid valve arrangement comprising: a fluid conduit arrangement having a first conduit and a second conduit, the first conduit being connectable with a supply of fluid pressure and the second conduit being connectable with a hydraulic consumer; characterized in that the fluid valve arrangement comprises a pressure controlling valve according to  claim 1 , and a fluid device ( 114 ;  501 ,  502 ;  601 ) causing a pressure drop between said first and second fluid conduits ( 105 ,  106 ), which fluid device ( 114 ;  501 ,  502 ;  601 ) is connected to one of the first or second ports ( 103 ,  104 ) of the pressure controlling valve, and that the pilot ports ( 107 ,  108 ) of the pressure controlling valve are connected on either side of the fluid device ( 114 ;  501 ,  502 ;  601 ), wherein the pressure controlling valve is arranged to control the pressure drop across the fluid device ( 114 ;  501 ,  502 ;  601 ) irrespective of the direction of fluid flow. 
     
     
         14 . A fluid valve arrangement according to  claim 13 , characterized in that the fluid device ( 114 ) comprises a throttle valve. 
     
     
         15 . A fluid valve arrangement according to  claim 14 , characterized in that the throttle valve ( 114 ) is controllable. 
     
     
         16 . A fluid valve arrangement according to  claim 13 , characterized in that the fluid device ( 501 ,  502 ) comprises a pair of controllable two-way valves connected in parallel. 
     
     
         17 . A fluid valve arrangement according to  claim 13 , characterized in that the fluid device ( 601 ) comprises a controllable three-way valve with a closed centre. 
     
     
         18 . A fluid valve arrangement according to any one of the above  claims 13 - 17 , characterized in that the valve arrangement further comprises an electronic control unit (ECU) for controlling at least the fluid device ( 114 ;  501 ,  502 ;  601 ). 
     
     
         19 . A fluid valve arrangement according to  claim 18 , characterized in that the spool ( 102 ) in the pressure controlling valve comprises an opening degree sensor ( 505 ,  605 ) which determines the position of the spool ( 102 ). 
     
     
         20 . A fluid valve arrangement according to  claim 19 , characterized in that the opening degree sensor ( 505 ,  605 ) is a position sensor 
     
     
         21 . A hydraulic valve arrangement according to  claim 19  or  20 , characterized in that the control device (ECU) is arranged to evaluate a non-linear correlation between the position of the slide and the opening degree of the valve arrangement.