A solenoid flow control valve includes: an inlet passage that allows an inlet port to communicate with a pilot pressure chamber; an outlet passage that allows the pilot pressure chamber to communicate with an outlet port; a fixed restrictor provided on the outlet passage; a pilot spool that closes the inlet passage when a solenoid is in a non-excitation state, whereas when solenoid is in an excitation state, opens inlet passage at an opening degree corresponding to an input current value to generate a pilot pressure corresponding to the input current value in pilot pressure chamber, the pilot spool opening a bypass passage when input current value is less and closes bypass passage when input current value is greater than or equal to the predetermined value; and a main spool that controls a flow rate from inlet to outlet port in accordance with the pilot pressure chamber's pilot pressure.

A control system for construction machinery includes a hydraulic cylinder operable by a working oil discharged from a hydraulic pump, a control valve arranged between the hydraulic pump and the hydraulic cylinder to control an operation of the hydraulic cylinder according to a position of a spool therein, the control valve having a first spool position for draining the working oil discharged from a chamber of the hydraulic cylinder to a drain tank, and a pressure compensated valve installed in a return hydraulic line through which the working oil discharged from the control valve at the first spool position is drained to the drain tank, the pressure compensated valve being configured to control a flow rate of the working oil passing through the pressure compensated valve according to a pressure difference between a front end and a rear end of the control valve.

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.

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 construction machine that precisely enables derivation of the operation characteristics of hydraulic actuators in a high-velocity area with less calibration operation is provided. A controller (10) has a calibration mode in which the controller (10) derives operation characteristics (α(xs)) representing a relation among a spool position (xs) of a meter-in valve (8a1), an operation velocity (Va) of a hydraulic actuator (4a), and a differential pressure (ΔP) across the meter-in valve (8a1), and is configured to, in a case where the spool position (xs) of the meter-in valve (8a1) has changed in a direction to increase the opening area of the meter-in valve (8a1) in the calibration mode, output a command signal to increase the opening area of a bleed-off valve (8b1) to a bleed-off solenoid proportional pressure-reducing valve (8b2) as a command signal to reduce the differential pressure (ΔP).

A construction machine that precisely enables derivation of the operation characteristics of hydraulic actuators in a high-velocity area with less calibration operation is provided. A controller (10) has a calibration mode in which the controller (10) derives operation characteristics (α(xs)) representing a relation among a spool position (xs) of a meter-in valve (8a1), an operation velocity (Va) of a hydraulic actuator (4a), and a differential pressure (ΔP) across the meter-in valve (8a1), and is configured to, in a case where the spool position (xs) of the meter-in valve (8a1) has changed in a direction to increase the opening area of the meter-in valve (8a1) in the calibration mode, output a command signal to increase the opening area of a bleed-off valve (8b1) to a bleed-off solenoid proportional pressure-reducing valve (8b2) as a command signal to reduce the differential pressure (ΔP).

The present disclosure relates to a hydraulic valve arrangement comprising a first pilot operated proportional directional control valve having a first valve member that is displaceable in a first and a second axial direction for controlling direction of supply and discharge of hydraulic fluid to and from a hydraulic actuator, a first proportional electro-hydraulic control valve for controlling displacement of the first valve member in the first axial direction, a second proportional electro-hydraulic control valve for controlling displacement of the first valve member in the second axial direction, and a second pilot operated proportional control valve having a second valve member configured to be controlled by the first and second proportional electro-hydraulic control valves via a shuttle valve arrangement. Individual meter-in and meter-out control of the hydraulic actuator is providable by having the second pilot operated proportional control valve configured to operate as a meter-in valve of the hydraulic actuator and the first pilot operated proportional directional control valve configured to operate as a meter-out valve of the hydraulic actuator, or by having the first pilot operated proportional directional control valve configured to operate as a meter-in valve of the hydraulic actuator and the second pilot operated proportional control valve configured to operate as a meter-out valve of the hydraulic actuator. The present disclosure also relates to a vehicle comprising a hydraulic actuator and a hydraulic valve arrangement for controlling the motion of the hydraulic actuator.

A selection system for hydraulic circuits has a cylinder selection processing unit; a database in which information pertaining to a combination of a plurality of apparatuses is registered in advance; combination selection processing units for reading information pertaining to the combination of the plurality of apparatuses in order of size from the database, and selecting an apparatus; and re-selection processing units for re-selecting an apparatus that is the next size up when a stroke time obtained by a simulation including some of the apparatuses selected by the combination selection unit exceeds an upper-limit stroke time, or when pressure after a return process is less than or equal to minimum working pressure.

A selection system for hydraulic circuits has a cylinder selection processing unit; a database in which information pertaining to a combination of a plurality of apparatuses is registered in advance; combination selection processing units for reading information pertaining to the combination of the plurality of apparatuses in order of size from the database, and selecting an apparatus; and re-selection processing units for re-selecting an apparatus that is the next size up when a stroke time obtained by a simulation including some of the apparatuses selected by the combination selection unit exceeds an upper-limit stroke time, or when pressure after a return process is less than or equal to minimum working pressure.

A stage assembly (10) includes a stage (14), and a fluid actuator assembly (24) that moves the stage (14). The fluid actuator assembly (24) includes a piston housing (32) that defines a piston chamber (34); (ii) a piston (36) that separates the piston chamber (34) into a first chamber (34A) and a second chamber (34B); (iii) a supply valve (38C) that controls the flow of the working fluid (40) into the first chamber (34A); and (iv) an exhaust valve (38D) that controls the flow of the working fluid (40) out of the first chamber (34A). The supply valve (38C) has a supply orifice (250G) having a supply orifice area, and the exhaust valve (38D) has an exhaust orifice (352G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber (34A), (34B).