Hydraulic drive device

A hydraulic drive device that supplies a working fluid to a hydraulic cylinder including a head-end port and a rod-end port, the hydraulic drive device comprising:

• a hydraulic pump motor including a suction port and a discharge port;
• an electric motor connected to the hydraulic pump motor;
• a directional control valve that switches a connection target of the head-end port between the discharge port and the suction port;
• a regeneration valve that opens and closes a regeneration passage connecting the head-end port and the rod-end port;
• an unloader valve that connects, to a tank, a discharge passage connecting the discharge port and the directional control valve;
• and
• a control device that controls an operation of each of the directional control valve, the regeneration valve, and the unloader valve according to a signal that is input to the control device, wherein
• in causing the directional control valve to connect the head-end port to the suction port, the control device causes the regeneration valve to open the regeneration passage and when a predetermined condition is satisfied, reduces an opening degree of the regeneration valve.

A hydraulic drive device that supplies a working fluid to a hydraulic cylinder including a head-end port and a rod-end port, the hydraulic drive device comprising:

• a hydraulic pump motor including a suction port and a discharge port;
• an electric motor connected to the hydraulic pump motor;
• a directional control valve that switches a connection target of the head-end port between the discharge port and the suction port;
• a regeneration valve that opens and closes a regeneration passage connecting the head-end port and the rod-end port;
• an unloader valve that connects, to a tank, a discharge passage connecting the discharge port and the directional control valve;
• and
• a control device that controls an operation of each of the directional control valve, the regeneration valve, and the unloader valve according to a signal that is input to the control device, wherein
• in causing the directional control valve to connect the head-end port to the suction port, when a predetermined condition is satisfied, the control device causes the directional control valve to reduce an opening degree between the head-end port and the suction port.