Valves

Claim 1

A valve structure for preventing filling deficiency problems in a pressure energy consumer such as a double acting hydraulic piston comprising an elongate housing having a longitudinal bore, an elongate cylindrical spool slidable in said bore, a pair of spaced work chambers surrounding and communicating with said bore and adapted to be connected to opposite sides of said pressure energy consumer, at least one pressure chamber intermediate the end of said bore communicating therewith delivering pressure fluid to said bore, at least two exhaust chambers, adjacent the work chambers and adapted to be connected to a reservoir, a second bore in each end of said spool, a brake piston in each said second bore, a third bore in said brake piston adjacent one end, at least one transverse passage in the wall of said brake piston communicating between the second and third bores, resilient means in each such second bore in said spool acting on said piston at the end opposite the third bore normally to urge the same toward one end of said second bore in said spool, a pair of cooperating restrictor passage means, one in said spool and one in said piston communicating from the third bore to the piston end adjacent the resilient means connecting the interior of said spool with both ends of each second bore in the spool on opposite ends of the piston, passage means in the brake piston communicating from the restrictor passages in the spool to the end of the second bore opposite the resilient means, a pair of spaced transverse passages at each end of the spool communicating with each bore in the spool and spaced to connect a work chamber and pressure fluid chamber at one end of the spool and a work chamber and exhaust chamber at the other end of the spool in a work position, an annular groove in the brake piston intermediate its ends capable of connecting said spaced passages within the bore in the spool whereby in said work position pressure fluid flows from a pressure fluid chamber through said transverse passages to a work chamber at one end of the spool, and the pressure fluid from said pressure fluid chamber through said restricting passages, at least one transverse passage in the brake piston and the passage means in the brake piston to act on the brake piston to move it against the resilient means to position the groove between the passages at the other end of the spool to regulate flow of fluid between the work chamber and exhaust chamber in accordance with the relative pressure in the pressure fluid chamber.