Abstract: A damper includes a coil that generates a magnetic field acting on magneto-rheological fluid flowing through a communication passage. A piston includes a concave portion formed on an outer peripheral surface of a piston core, a regulating member housed in the concave portion, an introduction flow passage that guides the magneto-rheological fluid in a first fluid chamber or a second fluid chamber into the concave portion such that the regulating member projects into the communication passage, and a fail valve that opens and closes the introduction flow passage. In the case where a current applied to the coil is a predetermined value or less, the regulating member projects into the communication passage.

Abstract: A damper includes a cylinder into which magneto-rheological fluid is sealed, a first fluid chamber and a second fluid chamber, a throttle passage, an electromagnetic coil, and a spacer. The first fluid chamber and the second fluid chamber are partitioned by a piston core in the cylinder. The throttle passage is formed between an inner peripheral surface of the cylinder and an outer peripheral surface of the piston core. The throttle passage communicates between the first fluid chamber and the second fluid chamber. The throttle passage provides a resistance to a flow of the passing magneto-rheological fluid. The electromagnetic coil generates a magnetic field acting on the magneto-rheological fluid flowing through the throttle passage. The spacer is mounted to the piston core and is configured to adjust a length of the throttle passage.

Abstract: A damper includes a cylinder that seals a magneto-rheological fluid, a piston slidably disposed in the cylinder, and a piston rod coupled to the piston. The piston includes a piston core, a flux ring, a plate, and a fixing nut. The piston core is mounted on the piston rod. The piston core has an outer periphery on which a coil is disposed. The flux ring forms a flow passage for the magneto-rheological fluid with the piston core. The plate is disposed on an outer periphery of the piston rod, has an outer peripheral surface housed in a one-end of the flux ring, and is bonded on the flux ring by brazing. The fixing nut sandwiches the plate with the piston core.

Abstract: A control system for a construction machine includes: a boom cylinder; a boom switching valve; a fluid pressure motor adapted to drive a motor generator by being rotated by means of a return fluid guided from a piston side chamber; a regeneration control valve adapted to adjust a first supply amount serving as a supply amount of a working fluid supplied from the piston side chamber to the boom switching valve, and a second supply amount serving as a supply amount of the working fluid supplied from the piston side chamber to the fluid pressure motor; and a controller adapted to control the regeneration control valve so that the second supply amount becomes smaller than the first supply amount in a case where a stroke amount of a spool becomes an upper limit value or more.

Abstract: A control system of a hybrid construction machine includes fluid pressure pumps, a regeneration motor, a rotating electric motor coupled to the regeneration motor, a storage battery configured to store electric power generated by the rotating electric motor, an assist pump provided coaxially to the regeneration motor to be driven by the rotating electric motor, the assist pump being configured to supply a working fluid to a fluid pressure actuator, and load adjusting units configured to change a load of the assist pump in accordance with a state of the storage battery.

Abstract: A control system of a hybrid construction machine includes fluid pressure pumps configured to supply a working fluid to a fluid pressure actuator, a regeneration unit having a regeneration motor for regeneration to be rotated by the working fluid discharged from a load side pressure chamber of the fluid pressure actuator, a rotating electric motor coupled to the regeneration motor, and a storage battery configured to store electric power generated by the rotating electric motor, and a variable throttle configured to bleed a portion of the working fluid obtained by excluding a flow rate of the working fluid guided to the regeneration motor from the working fluid discharged from the load side pressure chamber.

Abstract: A boom driving device comprises a boom control valve causing a boom cylinder to elongate and contract. The boom control valve returns a hydraulic fluid discharged from an working chamber of the boom cylinder to a tank in a boom descending position A part of the discharged hydraulic fluid is branched in the upstream of the boom control valve and is supplied to a generator through a regenerative passage for power generation. The regenerative passage is provided with a regenerative control spool valve. The regenerative control spool valve is opened when a flow cross-sectional area of the hydraulic fluid flowing from the working chamber to the tank reaches a predetermined area while the boom control valve is in the descending position. According to this construction, it is possible to alleviate a shock that may be generated at the start of power generation by the generator.

Abstract: A control system for a construction machine includes: a boom cylinder; a boom switching valve; a fluid pressure motor adapted to drive a motor generator by being rotated by means of a return fluid guided from a piston side chamber; a regeneration control valve adapted to adjust a first supply amount serving as a supply amount of a working fluid supplied from the piston side chamber to the boom switching valve, and a second supply amount serving as a supply amount of the working fluid supplied from the piston side chamber to the fluid pressure motor; and a controller adapted to control the regeneration control valve so that the second supply amount becomes smaller than the first supply amount in a case where a stroke amount of a spool becomes an upper limit value or more.

Abstract: A boom driving device comprises a boom control valve causing a boom cylinder to elongate and contract. The boom control valve returns a hydraulic fluid discharged from an working chamber of the boom cylinder to a tank in a boom descending position A part of the discharged hydraulic fluid is branched in the upstream of the boom control valve and is supplied to a generator through a regenerative passage for power generation. The regenerative passage is provided with a regenerative control spool valve. The regenerative control spool valve is opened when a flow cross-sectional area of the hydraulic fluid flowing from the working chamber to the tank reaches a predetermined area while the boom control valve is in the descending position. According to this construction, it is possible to alleviate a shock that may be generated at the start of power generation by the generator.