Abstract: A valve unit according to one embodiment includes valve equipment and control circuitry. The valve equipment includes a spool valve and a poppet-type logic valve. The spool valve switches a direction of supply and discharge of hydraulic oil to and from a hydraulic actuator. The logic valve is located between the spool valve and a hydraulic pump. The control circuitry controls the spool valve and the logic valve, such that if a supply flow rate of the hydraulic oil to the hydraulic actuator is less than a predetermined value, an opening area of a meter-in passage of the spool valve is less than an opening area of the logic valve, whereas if the supply flow rate of the hydraulic oil to the hydraulic actuator is greater than the predetermined value, the opening area of the meter-in passage of the spool valve is greater than the opening area of the logic valve.

Abstract: A state determination device (10100) includes: a signal acquiring unit (1030) configured to acquire a signal corresponding to each of a plurality of electrical wiring lines constituting the electrical equipment X and indicating an energization state of each electrical wiring line in association with each electrical wiring line; and a state determination unit (1011) configured to determine an operating state of the target electrical equipment that can be distinguished by a combination of the energization states corresponding the plurality of electrical wiring lines.

Abstract: Each of left and right direction switching valves includes: a pump port connected to a pump; a first compensation port connected to an upstream side of a corresponding pressure compensation valve; a second compensation port connected to a downstream side of the corresponding pressure compensation valve; a pair of supply/discharge ports connected to a corresponding travel motor; and a communication port. The communication ports of the left and right direction switching valves are connected by a communication line. When a spool shifts from a neutral position by the travel operation device, the pump port communicates with the first compensation port and the second compensation port communicates with one of the supply/discharge ports and the communication port. Each direction switching valve is configured wherein a degree of communication between the second compensation port and communication port increases in a shifting amount of the spool from the neutral position.

Abstract: A hydraulic circuit of a construction machine includes: a first pump line that connects a delivery port of a pump to a pump port of a first direction-switching valve; a second pump line that is branched off from the first pump line and is connected to a pump port of a second direction-switching valve; and a priority valve provided on the second pump line. The priority valve is configured to: fully open the second pump line when a pressure difference between a delivery pressure of the pump and a load pressure of a first actuator is greater than a setting value; and decrease an opening degree of the second pump line in accordance with decrease in the pressure difference when the pressure difference is less than the setting value.

Abstract: Each of left and right direction switching valves includes: a pump port connected to a pump; a first compensation port connected to an upstream side of a corresponding pressure compensation valve; a second compensation port connected to a downstream side of the corresponding pressure compensation valve; a pair of supply/discharge ports connected to a corresponding travel motor; and a communication port. The communication ports of the left and right direction switching valves are connected by a communication line. When a spool shifts from a neutral position by the travel operation device, the pump port communicates with the first compensation port and the second compensation port communicates with one of the supply/discharge ports and the communication port. Each direction switching valve is configured wherein a degree of communication between the second compensation port and communication port increases in a shifting amount of the spool from the neutral position.

Abstract: A hydraulic circuit of a construction machine includes: a first pump line that connects a delivery port of a pump to a pump port of a first direction-switching valve; a second pump line that is branched off from the first pump line and is connected to a pump port of a second direction-switching valve; and a priority valve provided on the second pump line. The priority valve is configured to: fully open the second pump line when a pressure difference between a delivery pressure of the pump and a load pressure of a first actuator is greater than a setting value; and decrease an opening degree of the second pump line in accordance with decrease in the pressure difference when the pressure difference is less than the setting value.