Pressure control valve

Abstract

A pilot poppet (44) is unseated when a pressure in a back pressure chamber (39) exceeds a spring (47) preload force to communicate the back pressure chamber (39) with a relief port (33). The pressure in a pressure port (32) is communicated to the back pressure chamber (39) through a tubular piston poppet (37) which extends through a relief poppet (31). The relief poppet (31) is unseated by a pressure difference between the back pressure chamber (39) and the pressure port (32) to communicate the pressure port (32) with the relief port (33) since communication of the back pressure chamber (39) with the relief port (33) causes the pressure in the back pressure chamber (39) to drop. The piston poppet (37) is moved to engage the pilot poppet (44) and block communication between the pressure port (32) and the back pressure chamber (39), thereby causing the pressure in the back pressure chamber (39) to drop further. The pilot poppet (44) seats when the pressure in the back pressure chamber (39) drops below the biasing force on the pilot poppet (44) which is equal to a spring (47) preload force minus the net force on the piston poppet (37). The piston poppet (37) unseats from the pilot poppet (44) causing the relief poppet (31) to seat when the pressure in the pressure port (32) drops below the pressure in the back pressure chamber (39). The pressure receiving area (AR) of the piston poppet (37) is made as small as possible to reduce the net force on the pilot poppet (44) and thereby the pressure drop in the pressure port (32). The ratio of a pressure receiving area (AP) of the pilot poppet (44) to the pressure receiving area (AR) of the piston poppet (37) is at least 1.1.

Dependencies are inferred from the claim text.