Vibration suppression control circuit

A vibration suppression control circuit installed in a work machine, the work machine including an actuator configured to move a work apparatus mounted to a vehicle body of the work machine in accordance with supply and discharge of pressure oil to and from a pressure chamber of the actuator, the vibration suppression control circuit being switchable between a vibration suppression control OFF state and a vibration suppression control ON state while the work machine is running,

• the vibration suppression control circuit comprising:
• a pressure accumulator;
• a pressure-regulating valve including,
• a supply/discharge port connected to the pressure accumulator via a supply/discharge line,
• a pump port,
• a tank port,
• a first signal chamber to which a pressure of the pressure accumulator is led as a first signal pressure, and
• a second signal chamber to which a pressure of the pressure chamber is led as a second signal pressure;
• a signal pressure supply control valve configured to control whether or not to allow supplying the first signal pressure to the first signal chamber;
• an open/close valve provided on a branch line, the branch line being branched off from the supply/discharge line and connected to the pressure chamber;
• and
• an open/close control valve configured to control an opened/closed state of the open/close valve in accordance with presence or absence of supply of an open/close signal pressure to the open/close control valve, wherein
• while the vibration suppression control circuit is in the vibration suppression control OFF state,
• the signal pressure supply control valve stops supplying the first signal pressure,
• the pressure-regulating valve is positioned in a first position in which the supply/discharge port is connected to the pump port, such that the pressure is accumulated in the pressure accumulator, and
• the open/close signal pressure is not supplied to the open/close control valve, such that the open/close valve is closed,
• when the vibration suppression control circuit switches from the vibration suppression control OFF state to the vibration suppression control ON state,
• the signal pressure supply control valve allows supplying the first signal pressure, and
• the pressure-regulating valve is brought into a second position in which the supply/discharge port is connected to the tank port, such that the pressure of the pressure accumulator decreases, and
• while the vibration suppression control circuit is in the vibration suppression control ON state, when the pressure of the pressure accumulator has become equal to the pressure of the pressure chamber,
• the pressure-regulating valve is brought into a third position in which the supply/discharge port is blocked, and
• the open/close signal pressure is supplied to the open/close control valve, such that the open/close valve is opened.