A construction machine is provided that can cause each hydraulic actuator to accurately operate according to operation by an operator in combined operation in which a hydraulic fluid of a hydraulic pump is subjected to flow dividing and is supplied to plural hydraulic actuators. A controller 10, in a case of determining that combined operation is being carried out, controls a regulator 7a in such a manner that the delivery flow rate of a hydraulic pump 7 becomes larger than the total target flow rate of plural hydraulic actuators 4a, 5a, and 6a, and controls the respective opening amounts of plural directional control valves 8a1, 8a3, and 8a5 in such a manner that the difference between the respective target flow rates of the plural hydraulic actuators and the respective inflow flow rates of the plural hydraulic actuators sensed by velocity sensors 12 to 14 becomes small.

The disclosure relates to a hydraulic driving system and a driving method for barring. The driving system comprises: three or more main drive hydraulic cylinders, which are divided into two groups to provide pulling and pushing forces to a driven impeller, each main drive hydraulic cylinder including a cylinder body and a piston rod which divides the cylinder body into a rod cavity and a godless cavity, wherein an oil line for the rod cavity and an oil line for the godless cavity of each main drive hydraulic cylinder are controlled by one control valve module; and a control device, which controls the control valve module according to wind and/or load signals, to simultaneously convert flow directions of hydraulic oil in the oil line for the rod cavity and the oil line for the godless cavity of at least one of the three or more main drive hydraulic cylinders.

A first required flow rate is calculated as a function of a first maximum allowable flow rate and a value of a first signal. A second required flow rate is calculated as a function of a value of the second signal. When the first maximum allowable flow rate is higher than a first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level, a first working fluid supply is controlled to discharge working fluid at a flow rate equal to the first capacity, and a second working fluid supply is controlled to discharge working fluid at a flow rate obtained by deducting the first capacity from the first maximum allowable flow rate, added to the second required flow rate.

A hydraulic system (40) for a work machine comprising a priority circuit (41) including at least a first priority actuator (47, 48) and a priority control valve (58) for controlling the supply of hydraulic fluid to the first priority actuator (47, 48) and for providing a load sense signal indicative of the load acting on the first priority actuator (47, 48); an auxiliary circuit (42) including at least a first auxiliary actuator (51) and at least a first auxiliary control valve (80) for controlling the supply of hydraulic fluid to the first auxiliary actuator (51); at least a first pump (46) for producing a flow of hydraulic fluid; and a priority valve (74) for distributing the flow from the pump (46) to the priority circuit (41) and auxiliary circuit (42) for operating the respective actuators thereof, with priority being given to the priority circuit (41) as a function of the load sense signal.

A hydraulic system may include an electrohydraulic control valve disposed in fluid communication between a source of pressured fluid and a hydraulic actuator. The hydraulic system may be controlled to correct for offset errors between a target actuator pressure and a current actuator pressure output from the control valve, without amplifying pressure oscillations in the fluid between the control valve and the hydraulic actuator.

A hydraulic boosting and regulating system includes an intensifier circuit and a regulator and employs low leak, low crossover valves.

A first required flow rate is calculated as a function of a first maximum allowable flow rate and a value of a first signal. A second required flow rate is calculated as a function of a value of the second signal. When the first maximum allowable flow rate is higher than a first capacity, the value of the first signal is a maximum level, and the value of the second signal is equal to or higher than a minimum level and equal to or lower than a maximum level, a first working fluid supply is controlled to discharge working fluid at a flow rate equal to the first capacity, and a second working fluid supply is controlled to discharge working fluid at a flow rate obtained by deducting the first capacity from the first maximum allowable flow rate, added to the second required flow rate.

An actuator includes: a casing; a pressure reducing valve and a piston. The pressure reducing valve is provided in the casing to reduce a pressure of a driving fluid supplied from an outside of the casing to a predetermined level. The piston is provided in the casing to form a pressure chamber together with the casing. The piston is driven by the driving fluid that has been pressure-reduced to the predetermined level.

An example valve includes: a plurality of ports comprising: (i) a first port, (ii) a second port configured to be fluidly coupled to a reservoir, and (iii) a third port configured to be fluidly coupled to a source of fluid; a spool slidably accommodated in a sleeve; an annular chamber formed between the spool and the sleeve, wherein the annular chamber is fluidly coupled to the first port, and wherein a first flow area is formed between the spool and the sleeve to fluidly couple the annular chamber to the second port via the first flow area; and a solenoid coil, wherein when the solenoid coil is energized, a solenoid force the spool, thereby causing the spool to move, forming a second flow area between the spool and the sleeve to fluidly couple the third port to the annular chamber via the second flow area.

An example valve includes: a plurality of ports comprising: (i) a first port, (ii) a second port configured to be fluidly coupled to a reservoir, and (iii) a third port configured to be fluidly coupled to a source of fluid; a spool slidably accommodated in a sleeve; an annular chamber formed between the spool and the sleeve, wherein the annular chamber is fluidly coupled to the first port, and wherein a first flow area is formed between the spool and the sleeve to fluidly couple the annular chamber to the second port via the first flow area; and a solenoid coil, wherein when the solenoid coil is energized, a solenoid force the spool, thereby causing the spool to move, forming a second flow area between the spool and the sleeve to fluidly couple the third port to the annular chamber via the second flow area.