Abstract: A work machine including a specific actuator that supplies hydraulic fluid from a plurality of hydraulic pumps includes: first and second hydraulic pumps communicating with a first hydraulic actuator; a first control valve returning hydraulic fluid delivered by the first hydraulic pump to a tank; and a load detection section that detects a load on the first hydraulic actuator. A control valve drive section drives the first control valve such that a communication area between the first hydraulic pump and the tank is enlarged corresponding to an increase in the load on the first hydraulic actuator; and a flow rate control section, during supply of the hydraulic fluid from the first and second hydraulic pumps to the first hydraulic actuator, controls to reduce a delivery flow rate of the first hydraulic pump corresponding to an increase in the load on the first hydraulic actuator.

Abstract: An object of the present invention is to provide a hydraulic control system for a work machine that is capable of reducing the loss caused by flow division while reducing a decrease in the speed of a hydraulic actuator due to a combined operation. The hydraulic control system for a work machine includes a first hydraulic actuator, one hydraulic pump, a second hydraulic actuator, and another hydraulic pump. The hydraulic control system further includes operating instruction detection means and pump flow control means. The operating instruction detection means detects that operating instructions are issued to the first hydraulic actuator and the second hydraulic actuator. The pump flow control means individually adjusts the delivery flow rate of the one hydraulic pump and the another hydraulic pump in accordance with operation amounts designated by the operating instructions for the first and second hydraulic actuators.

Abstract: A construction machine acquires efficiently and accurately the target surface to be displayed or controlled. The construction machine includes: a design surface information storage unit storing three-dimensional target shape as multiple design surfaces; a work equipment velocity vector acquisition unit detecting or estimating the velocity of work equipment; a work equipment position acquisition unit detecting or estimating the position of the work equipment; a target surface acquisition unit acquiring a principal target surface to acquire an estimated target surface that is potentially the next principal target surface; an operation control unit correcting the work equipment velocity; and a display unit displaying the positional relations between the work equipment position and the principal target surface.

Abstract: A work machine pump control system includes: a pump horsepower control valve (22) which causes a first urging force determining a limited horsepower (F) of a hydraulic pump and a second urging force due to a delivery pressure of the hydraulic pump to act on a spool in opposition to each other and which controls the pump flow rate such that it does not exceed the limited horsepower (F); a target pump flow rate computation section (42) computing a target pump flow rate based on an operation pressure (px) and a load pressure (py); a target horsepower computation section (41) which computes a required horsepower (Freq) corresponding to an operation pressure (px) from a relationship related to the operation pressure (px) and which computes a target horsepower (Ftar) based on the required horsepower (Freq); and a pump horsepower control section (35) which controls the pump horsepower control valve (22) such that the target pump flow rate (Qtar) is delivered with the limited horsepower (F) determined by the pump hor

Abstract: A wheel loader includes a working device, a lift cylinder 152 which is a hydraulic actuator that drives the working device, a hydraulic pump 220 that supplies hydraulic oil to the lift cylinder 152, a lift cylinder bottom pressure detector 252 that detects a pressure of the lift cylinder 152, a control valve 221 that controls the amount of hydraulic oil to be supplied from the hydraulic pump 220 to the lift cylinder 152, a vehicle acceleration detector 254 that detects a vehicle acceleration in a longitudinal direction, and a control device 240. The control device 240 determines whether the working device has started excavation, or not, based on the lift cylinder bottom pressure detected by the lift cylinder bottom pressure detector 252 and the vehicle acceleration detected by the vehicle acceleration detector 254.

Abstract: The control system for the hydraulic construction machine includes: a hydraulic actuator; a work device driven by the hydraulic actuator; a hydraulic pump supplying a hydraulic fluid to the hydraulic actuator; a pump flow rate control section controlling the delivery flow rate of the hydraulic pump; a pump horsepower control section controlling the horsepower of the hydraulic pump; and a target surface distance acquiring section measuring or computing a target surface distance that is the distance between a construction target surface on which the work device works and the work device. The pump flow rate control section is configured to perform control such that as the target surface distance decreases, the delivery flow rate decreases, and the pump horsepower control section is configured to perform control such that as the target surface distance decreases, the horsepower of the hydraulic pump increases.

Abstract: A control system for a construction machine stops an upper swing structure at a desired swing stop angle. A main controller sets a swing stop target angle at which an upper swing structure is to be stopped. A swing stoppability determination section reads an angle signal of the upper swing structure with respect to an undercarriage and an angle of a work implement, and determines whether the swing of the upper swing structure can be stopped at the swing stop target angle. A work implement is controlled in such a manner that an extension action of the work implement in a swing radial direction is prohibited or a contraction action of the work implement in the swing radial direction is executed in response to a signal that indicates whether the swing can be stopped and that is determined by the swing stoppability determination section.

Abstract: The lifetime of an electrical storage device is prolonged by reducing a speed of at least relevant one of hydraulic actuators for a specific operation to be performed by a work machine. This hybrid work machine includes a limit control section. When at least one specific operation defined as predetermined one or more among a plurality of work operations performed by the hybrid work machine is performed under condition of a degree of tendency to deterioration of the electrical storage device becoming higher, the limit control section reduces a speed of at least relevant one of the hydraulic actuators at a rate preset for the specific operation depending on the degree of tendency to deterioration of the electrical storage device.

Abstract: A hydraulic excavator includes: a hydraulic pump driven by power generated by an engine; a work device that operates by a plurality of hydraulic cylinders driven by power generated by the hydraulic pump; an actuator control section that controls the boom cylinder in such a manner that a tip end of a bucket is located on or above a target surface; a control point position calculation section that calculates a bucket claw tip position on the basis of angle sensors; and a power generator control section that imposes more limitations on output power ranges of the engine and the hydraulic pump when a distance between the claw tip position and the target surface is equal to or smaller than a threshold D than those when the distance between the claw tip position and the target surface is larger than the threshold D.

Abstract: A construction machine includes a control device having a reaction-force correction control section. When a difference between a target operator input and an actual operator input for a front member exceeds a preset range, the reaction-force correction control section executes correction to increase an operation reaction force to be applied by a reaction-force applying device to an operating unit operating an actuator driving the front member. When the difference falls within the range, the reaction-force correction control section executes correction to decrease the operation reaction force to be applied by the reaction-force applying device to the operating unit operating the actuator driving the front member.

Abstract: At times of a travel-solo state of the machine body, the outputting of unnecessary electric lever operating device signals caused by machine body oscillation due to the traveling is inhibited. At times of traveling work, the output limitation of electric lever operating device signals necessary for work is inhibited. A control system for a construction machine includes an electric lever operating device that outputs a command to a hydraulic actuator, a travel control lever device that outputs a command to a travel device, and a controller that outputs a drive command to a solenoid proportional valve that decompresses hydraulic fluid supplied from a pilot hydraulic source.

Abstract: A hydraulic system for a work machine includes a first hydraulic pump driving a swing hydraulic motor; a second hydraulic pumps driving a boom cylinder; a first pump displacement increase valve controlling a volume of the first hydraulic pump; a swing pilot pressure sensor detecting a swing operation amount; a boom raising pilot pressure sensor detecting a boom raising operation amount; and a controller controlling a control signal to the first pump displacement increase valve on the basis of the swing operation amount and the boom raising operation amount. The controller controls the control signal in such a manner that a delivery rate of the first hydraulic pump becomes higher as the swing operation amount is larger and an increasing rate of the delivery rate of the first hydraulic pump becomes lower as the boom raising operation amount is larger during a swing boom raising operation.

Abstract: Disclosed is a hydraulic control system of a construction machine capable of achieving a reduction in meter-out pressure loss in accordance with variation of a negative load acting on a hydraulic actuator and capable of preventing deterioration in operability even when an abnormal condition arises in a pressure sensor detecting the magnitude of a negative load.

Abstract: Disclosed is a hydraulic drive system capable of improving the fuel efficiency of a work machine by reducing the pressure loss and drag loss of a hydraulic pump. There are provided an electric motor M; a third pump P3 driven by the electric motor; a third pump hydraulic line L3 to which the delivered hydraulic fluid from the third pump is supplied; a third directional control valve V4 provided in the third pump hydraulic line, switch-operated by an arm operation device 19, and controlling the flow rate of the hydraulic fluid supplied to the arm cylinder 8 from the third hydraulic pump; and a controller 18 drive-controlling the electric motor, wherein the controller drives the third pump by the electric motor when a swing/arm combined operation is detected by pilot pressure sensors S6, S7, S10, S11.

Abstract: A motor-generator (27) is connected mechanically to an engine (21) and a hydraulic pump (23). The hydraulic pump (23) delivers pressurized oil to cylinders (12D) to (12F) in a working mechanism (12), a traveling hydraulic motor (25) and a revolving hydraulic motor (26). The revolving hydraulic motor (26) drives a revolving device (3) in cooperation with a revolving electric motor (33). An HCU (36) reduces outputs of the revolving electric motor (33), the revolving hydraulic motor (26), the boom cylinder (12D) and the like such that a ratio of a revolving speed of an upper revolving structure (4) and a movement speed of raising a boom (12A) is held to a ratio in a normal mode (NMODE) at the time of performing a compound movement of a revolving movement and a boom-raising movement in a low speed mode (LSMODE).

Abstract: A construction machine acquires efficiently and accurately the target surface to be displayed or controlled. The construction machine includes: a design surface information storage unit storing three-dimensional target shape as multiple design surfaces; a work equipment velocity vector acquisition unit detecting or estimating the velocity of work equipment; a work equipment position acquisition unit detecting or estimating the position of the work equipment; a target surface acquisition unit acquiring a principal target surface to acquire an estimated target surface that is potentially the next principal target surface; an operation control unit correcting the work equipment velocity; and a display unit displaying the positional relations between the work equipment position and the principal target surface.

Abstract: Provided is a hydraulic control system for a construction machine, including: a control valve (31) for controlling supply and discharge of hydraulic fluid to and from an arm cylinder (4); an operation lever (6) for controlling the position of a spool of the control valve (31); a meter-out flow passage (34) for passing therethrough hydraulic fluid discharged from the arm cylinder; a variable restrictor (23a) provided in the meter-out flow passage; pressure sensors (41, 42) for detecting a magnitude of a negative load applied by an external force to the arm cylinder in a same direction as an actuation direction of the arm cylinder; and a controller (45) for reducing an opening area of the variable restrictor (23a) according to an increase in the magnitude of the negative load calculated with a detection value from the pressure sensors (41, 42).

Abstract: A work machine including a specific actuator that supplies hydraulic fluid from a plurality of hydraulic pumps includes: first and second hydraulic pumps communicating with a first hydraulic actuator; a first control valve returning hydraulic fluid delivered by the first hydraulic pump to a tank; and a load detection section that detects a load on the first hydraulic actuator. A control valve drive section drives the first control valve such that a communication area between the first hydraulic pump and the tank is enlarged corresponding to an increase in the load on the first hydraulic actuator; and a flow rate control section, during supply of the hydraulic fluid from the first and second hydraulic pumps to the first hydraulic actuator, controls to reduce a delivery flow rate of the first hydraulic pump corresponding to an increase in the load on the first hydraulic actuator.

Abstract: The hybrid constructions machine has an engine rotation speed sensor 11A to detect a rotation speed NE of an engine 11, an engine state determination unit 20B to determine the state of output torque TE of the engine 11, a load torque estimation unit 20C to calculate load torque TP of a hydraulic pump 13, and an engine assistance limiting unit 20E to, when the rotation speed NE detected with the engine rotation speed sensor 11A is equal to or greater than a rotation speed N0, and the engine state determination unit 20B determines that the output torque TE of the engine 11 has not become minimum torque Tmin, or the load torque TP calculated with the load torque estimation unit 20C is lower than torque T1, limit motive-power assistance with the motor generator 12 to the engine 11.

Abstract: There are provided a work vehicle comprising a motor generator (6) driven by an engine, a hydraulic pump (4) driven by at least either of the motor generator and the engine, a work device (50) driven by hydraulic fluid from the hydraulic pump, a electric traction motor (9) driving wheels (61), an electrical storage device (11) connected to the motor generator and to the electric traction motor and charged electrically on the basis of a target SOC; and a control device (200) varying the target SOC for the electrical storage device (11) on the basis of total demanded power (Pf+Prun) of the hydraulic pump and the electric traction motor.