摘要:
A system has an actuator having a rotor or a linear piston, and ports for hydraulic fluid, an electro-mechanical sensor sensing position of the rotor or linear piston, a valve having a 1 plug in a bore of a valve body, the plug having cross bores aligning with passages within the valve body communicating inlet and outlet ports depending on relative position of the plug in the bore of the valve body, a servo motor to move the plug around or along the axis to different positions to align individual ones of the cross bores with individual ones of the passages communicating with individual ones of the ports, and a programmable controller coupled to the electro-mechanical sensor and to the servo motor, the controller enabled to control the servo motor to accomplish programmed movement and position of the rotor or linear piston of the hydraulically-driven actuator.
摘要:
The disclosure relates to a method for actuating a hydraulic valve arrangement, having a hydraulic continuously adjustable valve and having a hydraulic switching valve for providing a variable opening cross section, wherein an opening cross section threshold value is predefined, wherein, above the opening cross section threshold value, the switching valve is placed into a defined switching position and only the continuously adjustable valve is actuated, and wherein, below the opening cross section threshold value, the continuously adjustable valve is placed into a defined switching position and only the switching valve is actuated.
摘要:
A circuit for driving a hydraulic cylinder of a construction machine includes: a hydraulic pump; a tank; a control valve; a bottom side line; a rod side line; a quick return circuit having a branch line branched off from the bottom side line and led to the tank and a quick return valve which allows hydraulic fluid to be flowed through the branch line only when the control valve is switched to a contraction driving position; and a recycling circuit which supplies a part of return fluid discharged from a bottom side fluid chamber to a rod side fluid chamber of the hydraulic cylinder. The recycling circuit allows the hydraulic fluid to be flowed only from the bottom side fluid chamber into the rod side fluid chamber of the hydraulic cylinder only when the hydraulic cylinder is switched to the contraction driving position.
摘要:
A hydraulic control system is disclosed for use with a machine. The hydraulic control system may have a tank, a pump, an actuator, and a control valve configured to direct fluid from the pump to the actuator and from the actuator to the tank. The hydraulic control system may also have a pressure sensor to generate a first signal indicative of a pressure differential across the control valve, an operator input device to generate a second signal indicative of a desired movement of the actuator, and a controller. The controller may be configured to make a first determination of an opening amount of the control valve based on the second signal, and to make a second determination based on the first signal of whether the opening amount will result in overspeeding of the actuator. The controller may also be configured to reduce the opening amount based on the second determination.
摘要:
A method of operating a hydraulic system and hydraulic system for raising and lowering a boom in extreme climates. When the temperature is below a low temperature the system is operated open center while a variable displacement pump providing a constant flow of hydraulic fluid. When the temperature is between the low temperature and a moderate temperature the variable displacement pump provides at least a minimum flow of hydraulic fluid to the system, and the minimum flow decreases linearly with an increase of the temperature. When the temperature is above the moderate temperature, the system is operated closed center while maintaining at least a system pressure when in neutral and wherein the variable displacement pump provides hydraulic fluid to the actuator when a control valve is actuated.
摘要:
A hydraulic drive circuit is provided that can achieve high responsiveness, high precision, and high efficiency at a low cost in a hydraulic drive system popularly used in an industrial machine such as a press machine, a construction machine, and the like.A hydraulic drive circuit 1 supplies pressured liquid discharged from a main hydraulic pump P to drive a hydraulic actuator 2, and includes a first valve 4 arranged in a main flow line 3 that circulates pressured liquid discharged from the main hydraulic pump P to the hydraulic actuator 2, a second valve 5 to return the pressured liquid flowing into one liquid chamber of the hydraulic actuator 2 and discharged from the other liquid chamber to a tank T, and a sub-hydraulic pump 7 that is arranged between the main hydraulic pump P and the drive direction control valve 4 and uses the pressured liquid flowing in a branched flow line 6 branched from the main flow line 3 to increase a pressure and a volume of the hydraulic liquid in the main flow line 3 by predetermined quantities, respectively.
摘要:
An independent flow rate controlling hydraulic system for pressure control of an excavator, in which a hydraulic system of the excavator can be variably controlled via independent flow rate control. The hydraulic system includes a plurality of actuators which actuate a working apparatus, a pressure control-type hydraulic pump which feeds working fluid to the actuator, first and second electronic proportional control valves which are disposed at a piston-side inlet flow path and a load-side inlet flow path connected from the hydraulic pump to the actuators, third and fourth electronic proportional control valves which are disposed at a piston-side outlet flow path and a load-side outlet flow path connected from the actuators to a hydraulic tank, and a control unit which variably controls areas of the flow paths by controlling the first, second, third and fourth electronic proportional control valves depending on an amount by which a control stick is manipulated.
摘要:
A hydraulic system includes a variable displacement first pump, a first linear actuator fluidly connected to the first pump via a first closed-loop circuit, a variable displacement second pump, and second and third linear actuators fluidly connected to the second pump in parallel via a second closed-loop circuit. The system also includes a variable displacement third pump, a fourth linear actuator fluidly connected to the third pump via a third closed-loop circuit, a variable displacement fourth pump, and a first rotary actuator fluidly connected to the fourth pump via a fourth closed-loop circuit. The system further includes a second rotary actuator fluidly connected to the second pump in parallel with the second and third linear actuators. The system also includes a third rotary actuator fluidly connected to the third pump in parallel with the fourth linear actuator.
摘要:
A control valve device (19) controls supply and discharge of pressurized oil to and from a hoist cylinder (12) which tilts a vessel (3). A throttle (24C) that limits a flow rate of hydraulic oil which is discharged from a hydraulic pump (13) and flows in a return line (16) through a pump line (15), a first directional control valve (24) and a center bypass oil passage (23) is provided in the floating position (F) of the first directional control valve (24). When the first directional control valve (24) is in the floating position (F), the upstream side of the throttle (24C) is connected to the pump line (15), and the downstream side of the throttle (24C) is connected to the return line (16). In addition, a rod-side actuator line (18) communicated with rod-side oil chambers (12E, 12F) in the hoist cylinder (12) is connected to the pump line (15).
摘要:
A hydraulic system, and associated method of control, includes an operator input device, a source of hydraulic fluid flow, and a plurality of actuators. At least one valve associated with each actuator for controlling a flow of fluid to and from the actuator. A controller is responsive to a signal from the operator input device to calculate a hydraulic pressure to be supplied to each of the actuators. The controller controls the source of hydraulic fluid flow and the valves for powering the actuators with the calculated hydraulic pressure. The controller also monitors a sensed parameter to determine whether the actuators can be powered with the calculated hydraulic pressure, and in response to a determination that the actuators cannot be powered with the calculated hydraulic pressure, calculates a discrepancy ratio and modifies actuation of the actuators with the discrepancy ratio.