Three stage proportional control valve

A proportional inlet control valve for fluid connection to a high pressure fuel supply pump including an inlet plenum (112) for receiving feed fuel at a feed pressure, an inlet passage (122) for delivering feed fuel to a pumping chamber where a pumping plunger reciprocates between a pumping phase and a charging phase, and an outlet passage from the pumping chamber to a discharge valve, comprising:

• a cylindrical valve sleeve (102) defining a valve axis (104) and having a bypass port (106) at a back end of the sleeve, axially spaced from an intermediate metering port (108), which is axially spaced from a drain port (110) at a front end of the sleeve, with all said ports subject to feed fuel in the inlet plenum, and with said drain port subject to opening and closing of a leakage check valve (114) biased closed (116) with spring force (SI);
• an inlet valve seat (118) situated at the front end of the sleeve and defining a flow opening (120) into the inlet passage to the pumping chamber;
• an inlet check valve member (124) with associated spring (126) adapted to urge the check valve member against the seat with biasing force (SI);
• a spool valve (128) situated for axial displacement within the sleeve, having a front end (130) confronting the inlet check valve member and back end (132) subject to additive biasing forces of a metering spring (134) and a bypass spring (136), axially toward the inlet check valve member;
• said spool valve including an outer surface, an axially extending internal passage (138) fluidly connected to a fluid volume (140) at the front end of the spool valve, and a control port (142) through the outer surface at the back end of the spool valve, selectively alignable to fluidly connect the bypass port with the internal passage and fluid volume and selectively alignable to fluidly connect the metering port with the passage and fluid volume, while the fluid volume always remains in fluid communication with drain port and inlet valve seat such that fluid flowing through the opening of the inlet valve seat also flows through said fluid volume;
• a proportional solenoid actuator (144) magnetically coupled to the back end of the spool valve, for selective variable displacement of the spool valve into any one of three stages, consisting of
• a bypass stage wherein the combination of spring forces and solenoid actuation displaces the spool valve to a first position in which the control port aligns with the bypass port, the spool valve outer surface covers the metering port, the inlet check valve is open, and the leakage check valve is closed;
• a zero fueling stage, wherein the combination of spring forces and solenoid actuation displaces the spool valve to a second position in which the spool valve outer surface covers the bypass port and the metering port, the inlet check valve is cracked open, and the leakage check valve is closed during the charging phase and open during the pumping phase;
• and
• a metering stage, wherein the combination of spring forces and solenoid proportional energization displaces the spool valve to a variable third position in which the spool valve does not contact the inlet check valve, the outer surface covers the bypass port, variably uncovers the metering port, and the leakage check valve is closed during the charging phase and pumping phases.

A proportional inlet control valve for a high pressure fuel supply pump, comprising:

• a cylindrical valve sleeve (102) defining a valve axis (104) and having a bypass port (106) at a back end of the sleeve, axially spaced from an intermediate metering port (108), which is axially spaced from a drain port (110) at a front end of the sleeve;
• an inlet valve seat (118) situated at the front end of the sleeve and defining an opening (120) to a delivery passage;
• an inlet check valve member (124) with associated spring (126) that biases the check valve member against the inlet valve seat;
• a spool valve (128) situated for axial displacement within the sleeve, having a front end (130) confronting the inlet check valve member and a back end (132), said spool valve including an axially extending internal passage (138) fluidly connected to a fluid volume (140) at the front end of the spool valve, and a control port (142) at the back end of the spool valve, selectively alignable to fluidly connect the bypass port with the internal passage and fluid volume and selectively alignable to fluidly connect the metering port with the internal passage and fluid volume, while the fluid volume always remains in fluid communication with drain port and inlet valve seat;
• a bypass spring (136) and a metering spring (134) situated at the back end (132) of the spool valve for biasing the spool valve axially toward the inlet check valve member, wherein the bypass spring (136) has a longer free length and a lower spring rate than the free length and spring rate of the metering spring (134);
• a proportional solenoid actuator (144) magnetically coupled to the back end of the spool valve, for selective variable displacement of the spool valve, whereby combinations of forces applied by said solenoid and said bypass, metering, and inlet check valve springs selectively position the spool valve to uncover and cover the bypass port and the metering port and open or close the inlet check valve member against the inlet valve seat.