| 摘要 |
<p>PROBLEM TO BE SOLVED: To simplify adjusting the spring rate of a return spring for a control valve in a control system. SOLUTION: A control valve of pilot flow-rate amplifying type comprises a pilot spool 54 which controls pilot flow rate, and a main poppet 41 which controls a main flow rate by letting the pilot spool 54 control the pilot flow rate. The pilot spool 54 includes a load pressure sensing part 77 which senses load pressure Pload, a return spring 62 for pushing back the pilot spool 54 to a neutral position, and a push solenoid 57 which causes thrust to be generated against the return spring 62 for displacing the pilot spool 54. A gain control device, depending on the load pressure Pload, corrects the gain of an electrical signal supplied to the push solenoid 57 so as to generate thrust, in turn controlling the force of the return valve 62 and further improving the performance of the control valve.</p> |
