An object of the present invention is to provide a construction machine that allows easy and accurate calibration of a pressure sensor and enables accurate control of hydraulic actuators. A controller increases the delivery pressure of a hydraulic pump in a state in which first and second meter-out valves and a second meter-in valve are closed and in which a first meter-in valve is opened, and calibrates a first pressure-calculation map such that a pressure calculated on the basis of the first pressure-calculation map matches a pressure calculated on the basis of a supply-pressure-calculation map, and increases the delivery pressure of the hydraulic pump in a state in which the first and second meter-out valves and the first meter-in valve are closed and in which the second meter-in valve is opened, and calibrates a second pressure-calculation map such that a pressure calculated on the basis of the second pressure-calculation map matches the pressure calculated on the basis of the supply-pressure-calculation map.

A hydraulic machine is provided. A first flow control valve directs fluid from a first fluid supply to a first actuator when the first flow control valve is in a first position. A conflux control valve directs fluid from the first fluid supply to a second flow control valve when the conflux control valve is in a conflux position. The second flow control valve directs fluid from a second fluid supply and the first fluid supply to a second actuator when second flow control valve is in a second position. A bypass path allows the first fluid supply to communicate with the conflux control valve by passing around the first flow control valve.

Flow control over a hydraulic pump and flow dividing control of a plurality of directional control valves associated with actuators can stably be exercised even in a case in which differential pressures across the directional control valves are quite low, an abrupt change in a flow rate of the hydraulic fluid supplied to each actuator is prevented and excellent combined operability is realized even in an abrupt change in a demanded flow rate at a time of transition from a combined operation to a sole operation, and realizing excellent combined operability, and a meter-in loss in each directional control valve is reduced to realize high energy efficiency. Demanded flow rates of the directional control valves are calculated from input amounts of operation levers, openings of flow control valves are controlled using the demanded flow rates, a meter-in pressure loss of a predetermined directional control valve is calculated from the demanded flow rates and meter-in opening areas of the directional control valves, and a set pressure of an unloading valve is controlled using a value of the meter-in pressure loss.

A first flow path area at a position where one of multiple openings of a sleeve and one of multiple grooves of a spool overlap with each other is different in size from a second flow path area at a position where another one of the openings of the sleeve and another one of the grooves of the spool overlap with each other. The one opening and the one groove form a flow path for connecting one of one pressure chamber and the other pressure chamber to a fluid supply source, due to displacement of the spool. The other opening and the other groove form a flow path for connecting another one of the other pressure chamber and the one pressure chamber to a fluid discharge port, due to the displacement of the spool.

An electric-powered fail-safe actuator for use with a valve, where the actuator stores potential energy for conversion to kinetic energy to close or open the valve to the fail-safe position.

A flow control valve includes a valve body having an inner circumferential surface defining a longitudinal bore to which first and second fluid passages are connected. A spool is slidably inserted into the bore to allow a flow of fluid from the first to second fluid passage. A valve regulates a flow rate of fluid flowing through the first fluid passage. A first seat surface is defined between an area in which the first fluid passage is connected to the bore and an area in which the second fluid passage is connected to the bore. When the flow of fluid from the first to second fluid passage is initiated, an area of a gap between the first seat surface and the spool on a plane taken in a transverse direction is 5%50%, preferably 10%20% of an area of an opening defined by the first seat surface.

An example valve includes: a first port fluidly coupled to a chamber of an actuator; a second port fluidly coupled to a reservoir; a third port configured to provide an output pilot fluid signal and receive an input pilot fluid signal; a fourth port fluidly coupled to a source of fluid; a main poppet configured to be subjected to a first fluid force of fluid received at the first port acting on the main poppet in a proximal direction to cause the main poppet to be seated at a main poppet seat to block fluid flow to and from the first port; a piston configured to move axially to contact the main poppet; and a spool that is axially movable between a first position and a second position to operate the valve in either a pilot-operated check valve mode of operation or a proportional flow control mode of operation.

A control valve assembly for indirect pneumatic control and method for controlling a working fluid pressure, which enable precise, sensitive and speed-variable controlling. The assembly includes two valve units, a working fluid inlet, and a control fluid inlet. A working fluid channel connects the working fluid inlet through the two valve units to an outlet. A valve piston arranged within a valve cylinder of the valve units is movable between open and closed positions. A spring element biases the valve piston toward the closed position, and a control pressure chamber applies a control pressure counteracting the spring element's bias. When a control pressure is applied in the first chamber, the first valve piston is moved to the open position. Two opposite valve surfaces form a valve opening opened at varying widths when the valve piston is moved in the valve cylinder because of a changing control pressure, and the working pressure can be finely adjusted corresponding to the valve opening width depending on the control pressure.

A flow control valve apparatus includes: a housing including two pump ports, two tank ports, a first supply/discharge port, a second supply/discharge port, and a spool hole; a first spool configured to switch a connection status among one of the pump ports, one of the tank ports, and the first supply/discharge port depending on a position of the first spool; a first actuator configured to move the first spool to each of a first supply position and a first discharge position; a second spool configured to switch a connection status among the other pump port, the other tank port, and the second supply/discharge port depending on a position of the second spool; and a second actuator configured to move the second spool to each of a second supply position and a second discharge position. The first spool and second spool are inserted in the spool hole so as to reciprocate.

A control system and method for controlling the positioning of an adjustable deflector plate employed in a harvesting combine to adjust a side-to-side flow of crop residue to spreaders associated with the combine and the distribution thereby. The deflector plate is operably extendable into the flow of crop residue to redirect crop residue impinging the deflector plate. The deflector plate is adjusted based upon a comparison between the open/closed states of valves associated with the control system.