Method and mechanism to reduce flow forces in hydraulic valves

A valve assembly including a mechanism for fluidically controlling forces, comprising:

• a valve body having a cylindrical valve chamber, the valve chamber fluidically connecting a first flow passage and a second flow passage;
• a cylindrical valve arranged for sliding linear reciprocation in the cylindrical valve chamber along an axis, the valve including a first and second lands in spaced relation, each the lands sliding in contact against the valve chamber guiding linear translation of the valve, the first land controlling fluid flow between the first and second flow passages through the valve chamber, wherein fluid pressure contained in the valve chamber between first and second lands applies opposing axial forces on the first and second lands;
• the first land including a first annular control edge at first diameter, and a second annular control edge at a second diameter, the first diameter being smaller than the second diameter, further comprising a first cut out shoulder extending radially between the first annular control edge and the second annular control edge;
• a first restriction between the first control edge and the valve chamber;
• and
• a second restriction between the second control edge and the valve chamber, wherein an intermediate pressure region is provided between the first and second restrictions adapted to effect an axial force on the first cut out shoulder for counteracting flow induced forces.

A method of counteracting flow induced forces in a valve assembly comprising a valve and a valve body, the valve body including an axial valve chamber and a radial passage, the valve being translatable in the axial valve chamber, comprising:

• pressurizing fluid in the axial passage to a pressure greater than the radial passage;
• controlling fluid flow from an axial valve chamber radially outwardly to a radial passage with the valve, the controlling of fluid causing an axial flow induced force to develop across the valve;
• restricting the fluid flow from the axial valve chamber to the radial passage with a first restriction between the valve and the valve body;
• restricting the restricted fluid flow with a second restriction between the valve and the valve body radially outward of the first restriction, thereby forming an intermediate pressure region between the first and second restrictions, the intermediate pressure region having a fluid pressure between that of the axial valve chamber and the radial passage;
• and
• applying a counteracting axial force to the valve with the intermediate pressure region acting on the valve, the counteracting axial force counteracting the axial force of the axial flow induced force.