A control system for a work machine includes a plurality of hydraulic pumps that discharge hydraulic oil, a hydraulic cylinder that moves a working equipment element, a plurality of flow rate control valves that are respectively connected to the hydraulic pumps and adjust a flow rate of the hydraulic oil supplied to the hydraulic cylinder, a plurality of supply flow paths respectively connected to the of flow rate control valves, a meter-in flow path that connects a collective part of the supply flow paths and an inlet of the hydraulic oil in the hydraulic cylinder, a plurality of discharge flow paths respectively connected to the flow rate control valves, a meter-out flow path that connects a collective part of the discharge flow paths and an outlet of the hydraulic oil in the hydraulic cylinder, and a throttle disposed in the meter-out flow path.

A control system for hybrid construction machine includes: an operation valve for operating a boom; a variable displacement type fluid pressure motor; a distribution mechanism adapted to adjust a flow to be distributed to the fluid pressure motor; a motor generator adapted to be rotated integrally with the fluid pressure motor; a variable displacement type assist pump adapted to be rotated integrally with the motor generator; a distribution mechanism control unit adapted to control the distribution mechanism; a tilt angle control unit adapted to control tilt angles of the fluid pressure motor and the assist pump; and a motor generator control unit adapted to maintain a rotation speed of the motor generator at a target rotation speed. The target rotation speed at the time of boom regeneration control is set to higher than the target rotation speed in a case where only an assist control is carried out.

This hydraulic drive system includes: a hydraulic pump that supplies a working fluid to a hydraulic actuator; a meter-in control valve that controls a flow rate of the working fluid flowing from the hydraulic pump to the hydraulic actuator; a meter-out control valve that controls a flow rate of the working fluid being drained from the hydraulic actuator into a tank; and a regeneration valve that supplies, to the hydraulic actuator, the working fluid drained from the hydraulic actuator. The meter-out control valve is connected to the hydraulic actuator in parallel with the regeneration valve.

Disclosed are a device for controlling a regenerated flow rate for a construction machine and a method for controlling the same, the device being able to supply a large chamber of an arm cylinder with a part of operating oil, which is discharged from the arm cylinder to an operating oil tank during arm-in driving, and regenerating the same. The present invention provides a device for controlling a regenerated flow rate for a construction machine, the device being characterized by comprising: a variable capacity-type hydraulic pump and a pilot pump; an arm cylinder driven by operating oil supplied from the hydraulic pump; a variable arm regeneration valve installed in a passage between the arm cylinder and the operating oil tank; and an electronic proportional valve installed in a passage between the pilot pump and the arm regeneration valve.

This hydraulic drive system includes: a hydraulic pump that supplies a working fluid to a hydraulic actuator; a meter-in control valve that controls a flow rate of the working fluid flowing from the hydraulic pump to the hydraulic actuator; a meter-out control valve that controls a flow rate of the working fluid being drained from the hydraulic actuator into a tank; and a regeneration valve that supplies, to the hydraulic actuator, the working fluid drained from the hydraulic actuator. The meter-out control valve is connected to the hydraulic actuator in parallel with the regeneration valve.

A pneumatic device having a pneumatic cylinder and a piston movably mounted in the pneumatic cylinder to divide an interior of the pneumatic cylinder into two chambers. The chambers are connected to a line network having a valve assembly. The line network, in a plurality of operating states of the valve assembly serving for venting the respective chamber, connects the respective chamber to at least a respective selected one of a plurality of outflow openings, of the pneumatic device, and in a further operating state of the valve assembly, disconnects the respective chamber from the outflow opening. A control installation of the pneumatic device adjusts the operating state of the valve assembly. The line network is designed so that, in at least three of the operating states for venting the respective chamber, the connection between the respective chamber and the outflow opening is established by mutually dissimilar flow resistances.

Forklift truck (1) mounted on a carrier vehicle and comprising a frame (16), forks (2), a lifting cylinder (4) for relatively moving the forks (2) and the frame (16) so as to allow, in a handling mode of operation, wherein the forks (2) are mounted so as to move freely upwards and downwards relative to the ground, the forks (2) to be lifted, and in a carrying mode of operation, wherein the forks (2) are in the high position and immobilised so that they do not move upwards and downwards relative to the ground, to allow the frame to be lifted (16), each chamber (7, 8) of the cylinder (4) being provided with a connecting fluid duct which connects the chamber (7; 8) to a hydraulic source. In the handling mode of operation, the forks (2) form an element which is used to actuate the lifting cylinder (4) in the direction in which the forks (2) are lowered, the fluid ducts of the chambers (7, 8) of the lifting cylinder (4) being connected to one other by a fluid connection provided with a closing member in the closed position at least in the carrying mode of operation when the frame (16) is being driven in the direction in which the frame (16) is lifted.

This hydraulic drive device drives a hydraulic cylinder by supplying and draining a working fluid via a head-end port and a rod-end port and includes: a hydraulic pump motor that is rotatably driven by and discharges the working fluid; an electric motor connected to the hydraulic pump motor; a directional control valve that switches the direction of the working fluid flowing between the hydraulic pump motor and the head-end port; a regeneration valve that opens and closes a regeneration passage connecting the head-end port and the rod-end port; a pressure sensor that measures inflow pressure at the hydraulic pump motor; and a control device that, when causing the regeneration valve to open the regeneration passage and causing the directional control valve to connect the head-end port and the hydraulic pump motor, controls the opening degree of the regeneration valve according to the inflow pressure of the working fluid.

This hydraulic drive device drives a hydraulic cylinder by supplying and draining a working fluid to and from a head-end port and a rod-end port and includes: a hydraulic pump motor is rotatably driven by and discharges the working fluid; an electric motor connected to the hydraulic pump motor; a directional control valve that switches the direction of the working fluid flowing between the hydraulic pump motor and the head-end port; a regeneration valve that opens and closes a regeneration passage connecting the head-end port and the rod-end port; a temperature sensor that measures the coil temperature of the electric motor; and a control device that controls the opening of the regeneration valve according to the coil temperature measured by the temperature sensor when causing the regeneration valve to open the regeneration passage and causing the directional control valve to connect the head-end port and the hydraulic pump motor.

This hydraulic drive system includes: a hydraulic pump that supplies a working fluid to a hydraulic actuator; a meter-in control valve that controls a flow rate of the working fluid flowing from the hydraulic pump to the hydraulic actuator; a meter-out control valve that controls a flow rate of the working fluid being drained from the hydraulic actuator into a tank; and a regeneration valve that supplies, to the hydraulic actuator, the working fluid drained from the hydraulic actuator. The meter-out control valve is connected to the hydraulic actuator in parallel with the regeneration valve.