COMPONENT OPERATION / Pump Device Control by Flow Rate Control Pressure of Fan Pump Control Solenoid Valve Decreasing Flow Rate (Regulator Operation with Flow Rate Control Pressure Increasing) 1. When fan pump control solenoid valve (17) is ac- tivated, flow rate control pressure Pi in proportion to the movement of fan pump control solenoid valve (17) is routed to pilot piston (22) through spool (16). When pilot pressure Pi increases, pi- lot piston (22) moves to the right until pilot piston (22) balances with spring (20). 2. Pilot piston (22) moves lever 1 (18) through pin (21). Lever 1 (18) rotates counterclockwise about pin (19) fixed to the axial plug. 3.
Pin (7), which is attached to feedback lever (13), is inserted into hole (23) of lever 1(18). Therefore, feedback lever (13) rotates clockwise about pin (14) by the turning of lever 1 (18) and moves spool (2) to the right. 4. When spool (2) moves, own pump delivery pres- sure P3 acts on the large chamber in servo pis- ton (15) through spool (2). Although own pump delivery pressure P3 acts on the small chamber, servo piston (15) moves to the right due to the difference in pressure receiving area. 5. As the pump displacement angle reduces ac- cording to the movement of servo piston (15), pump delivery flow rate decreases. 6.
When servo piston (15) moves, feedback lever (13) moves through pin (14). As neither pilot pis- ton (22) nor lever 1 (18) moves, feedback lever (13) rotates counterclockwise about pin (7) and moves spool (2) to the left. When the notches on sleeve (3) and spool (2) are closed completely, own pump delivery pressure P3 does not act on the large chamber in servo piston (15) and servo piston (15) stops moving. 7. With the above operation, pump delivery flow rate decreases according to increasing amount of flow rate control pressure Pi. NOTE: Refer to the pilot circuit in Hydraulic Sys- tem group / SYSTEM.
Q (Flow Rate) Pi (Flow Rate Control Pressure) 16 To Fan Motor Pr Pi 22 17 3 2 13 15 14 P3 Pilot Pump Fan Pump T1J1-03-01-022 T3-1-16