INJECTION BOOSTER SWITCHING VALVE AND INJECTION BOOSTER SWITCHING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an injection booster switching method which suppress a deterioration in control responsiveness in blocking a port connected with a speed control hydraulic source even when the oil feed amount to be fed out of the hydraulic source into an injection cylinder is large and controls the feed source of pressure oil into the injection cylinder by switching from the speed control hydraulic source to the booster control hydraulic source.;SOLUTION: The present invention is attained by a speed control preparation process of turning a first port 41 and a second port 42 of a first pressure chamber 32a in communication and keeping the pressure chamber partitioned from the second pressure chamber 32b, a speed control process of maintaining the open state of the second port 42 while second port opening force is larger than second port blocking force, and a booster switching process of making a first moving spool 51 block the second port 42 by an increase in the opening force below the blocking force, and feeding pressure oil out of a booster control hydraulic source 14 from the third port 43 into an injection cylinder 10 with the small diameter part 51b of the spool 51.;SELECTED DRAWING: Figure 4;COPYRIGHT: (C)2017,JPO&INPIT