A hydraulic system for a working machine, includes a first hydraulic pump to output an operation fluid, a hydraulic device to be operated by the operation fluid, an operation member to be operated, a control valve to control the hydraulic device based on an operation extent of the operation member, a holding member to set a held operation extent that is the operation extent held in the operation of the operation member, and a pedal to be operated to change the held operation extent set by the holding member.

A hydraulic system for a working machine includes a hydraulic pump, a first hydraulic actuator, a second hydraulic actuator, a first control valve to control the first hydraulic actuator, a second control valve to control the second hydraulic actuator, and a discharge fluid tube in which the operation fluid flows. The discharge fluid tube is connected to the first control valve. The hydraulic system includes a first fluid tube in which a return fluid flows toward the second control valve. The first fluid tube couples the first control valve to the second control valve. The hydraulic system includes a second fluid tube coupling the first fluid tube and the discharge fluid tube, a first throttle disposed on the first fluid tube, and a second throttle disposed on the second fluid tube, the second throttle having an opening area smaller than an opening area of the first throttle.

An energy regeneration device capable of controlling flow of a working fluid discharged from an actuator while regenerating energy from the working fluid, and a work machine including the foregoing device, include a boom cylinder, an inertial fluid container, an oil tank, an accumulator, a low-pressure-side opening/closing device, and a high-pressure-side opening/closing device. A calculation unit calculates a duty ratio for opening/closing the low-pressure-side opening/closing device and the high-pressure-side opening/closing device in accordance with a desired flow rate of a hydraulic fluid discharged from the boom cylinder. A regeneration control unit selects alternately the low-pressure-side opening/closing device and the high-pressure-side opening/closing device as a destination with which the inertial fluid container communicates in accordance with the calculated duty ratio, and supplies the discharged hydraulic fluid to an accumulator.

A pump device includes a variable capacity first pump, a tilt actuator that controls a tilt angle of a swash plate of the first pump in accordance with the control pressure, a regulator that regulates the control pressure in accordance with a front-rear differential pressure of a control valve, a fixed capacity second pump driven by the same drive source as the first pump, the control actuator that operates in accordance with the front-rear differential pressure a resistor so as to drive the regulator to reduce the control pressure in response to an increase in the front-rear differential pressure of the resistor, an auxiliary passage that leads an auxiliary pressure to the control actuator, the auxiliary pressure acting on the control actuator against a upstream pressure of the resistor, and a switch valve that switches between connecting and shutoff the auxiliary passage.

A neutral valve includes a spool inserted in a housing so as to be movable in a predetermined direction, the spool configured to move to a neutral position set such that a first and second port are connected to each other through a valve passage, a first offset position located at neutral position's first side in the predetermined direction and set such that second port and valve passage are disconnected from each other, and a second offset position located at neutral position's second side in the predetermined direction and set such that first port and valve passage are disconnected from each other. The spool's outer peripheral portion includes a first pressure receiving surface receiving first port's fluid pressure to be pushed toward the first side in the predetermined direction and a second pressure receiving surface receiving second port's fluid pressure to be pushed toward second side in the predetermined direction.

A hydraulic drive including at least one hydraulic cylinder that includes a piston chamber, an annulus, and a piston that separates the piston chamber from the annulus. The hydraulic drive also includes a first hydraulic pump hydraulically connected with the piston chamber, a second hydraulic pump hydraulically connected with the annulus, a third hydraulic pump, and a directional control valve that has a first switching position and a second switching position. The third hydraulic pump in the first switching position of the directional control valve is hydraulically connected with the piston chamber, and the third hydraulic pump in the second switching position of the directional control valve is not hydraulically connected with the piston chamber.

A haptic system includes a haptic ring that is worn on the finger of a user. The haptic ring includes a flexible tube that is positioned against the finger pad of the user and configured to transport a fluid across the finger pad of the user. A first pump is configured to pump a warm fluid into the flexible tube and a second pump is configured to pump a cold fluid into the flexible tube, thereby providing a haptic sensation of temperature. A valve is positioned downstream of the haptic ring that is configured to open and close to modulate the pressure of the fluid, thereby providing a haptic sensation of pressure and/or vibration to the finger pad of the user. The haptic ring is unobtrusive and therefore does not significantly interfere with the ability of the user to perceive tactile sensations of the real world.

A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53. Variable horsepower control tables 52r and 53r are provided in the electric motor rotational speed control sections 52 and 53, and limit values q1*limit and q2*limit for a virtual displacement of the variable horsepower control tables 52r and 53r are changed such that a charge state of a power storage device 170 and a charge state of another power storage device 270 become equal to each other.

Provided is a hydraulic pump arrangement including a plurality of motor-pump units connected to a common confluence, wherein each motor-pump unit of the hydraulic pump arrangement includes a pump realized provide pressurized fluid at its outlet; a motor arranged to drive the pump; a bypass valve configured to relieve pressure at the pump outlet; and wherein the hydraulic pump arrangement further includes a controller configured to receive a feedback signal from each motor-pump unit and to actuate the bypass valve of a motor-pump unit on the basis of the motor speed of that motor-pump unit. Further provided is a method of operating such a hydraulic pump arrangement, and a wind turbine including a number of such hydraulic pump arrangements.

Provided is a construction machine capable of detecting a stuck-open state of a surplus flow control valve in real time during operation without involving a reduction in the operational speed. The construction machine is equipped with: a surplus flow control valve control section configured to output a closing command to a first surplus flow control valve at the operation start when an operation amount signal of an operation lever device is detected; a pump delivery control section configured to output a delivery flow rate command to an adjustment section of an open circuit pump; an assist valve control section configured to continue to output a closing command from before to an assist valve; a sticking detection determination section configured to compare a pressure signal with a previously set threshold value and determining that the surplus flow control valve is in a stuck-open state when the pressure signal is less than the threshold value and determining that the surplus flow control valve is normal when the pressure signal exceeds the threshold value; and a stop signal generating section configured to input therein a sticking determination signal, output in the case of a stuck-open state a control signal maintaining a closed state of the assist valve to the assist valve control section, and output in the case of a normal state a control signal causing the assist valve to perform an opening operation to the assist valve control section.