Electrically modulated pressure regulator valve with variable force solenoid

A variable force solenoid valve assembly for controllably reducing a fluid inlet pressure to an outlet control pressure in response to an electrical input signal, comprising:

• a solenoid assembly including an energization coil assembly defining a longitudinal bore, an armature disposed in said bore and adapted to translate in response to said electrical input signal energizing said coil assembly, pole means for defining a working air-gap across which magnetic fields are transferred for generating an attractive force between said pole means and said armature which urges said armature to move toward said pole means when said coil assembly is energized, and spring means for normally biasing said armature away from said pole means;
• a valve body coupled to said solenoid assembly and including an inlet passage in fluid communication with fluid at said fluid inlet pressure, an outlet passage in fluid communication with fluid at said outlet control pressure, an exhaust passage in fluid communication with a sump, and a central bore axially aligned with said armature and which communicates with each of said passages, said central bore having a first bore segment in fluid communication with said inlet passage, a second bore segment in fluid communication with said exhaust passage, and an undercut segment formed between said first and second bore segments and which is in fluid communication with said outlet passage;
• a spool valve disposed within said valve body central bore and secured to said armature for translational movement therewith, said spool valve having a central stem and a plurality of lands extending radially therefrom, said spool valve including a first land retained in said first bore segment to define a first chamber therewith, a stepped second land retained in said undercut to define a second chamber therewith, and a third land retained in said second bore segment to define a third chamber therewith, said first chamber provided between said first and second spool valve lands, said third chamber defined between said second and third spool valve lands, and said second chamber defined between said second land of said spool valve and said undercut;
• a first fluid restriction associated with said second spool valve land for controllably restricting fluid communication between said first chamber and said second chamber;
• and
• second fluid restriction associated with said second spool valve land for controllably restricting fluid communication between said second chamber and said third chamber;
• whereby controlled energization of said coil assembly causes movement of said armature toward said pole means which produces corresponding movement of said spool valve within said valve body central bore for decreasing the flow of fluid through said first fluid restriction and increasing the flow of fluid through said second fluid restriction so as to decrease the outlet control pressure and, deenergization of said coil assembly causes said spring means to urge said armature and said spool valve to move away from said pole means for increasing the flow of fluid through said first fluid restriction and decreasing the flow of fluid through said second fluid restriction so as to increase the outlet pressure.