摘要:
A hydraulic system is provided, the hydraulic system including a hydraulic load defining a first chamber and a second chamber. Additionally, the hydraulic system includes a pressure source, a fluid storage vessel, a load sense line, and a spool valve. The spool valve fluidly connects the fluid storage vessel to one of the first or second chambers and fluidly connects the pressure source to the other of the first or second chambers. A bypass line is also provided defining a flow path between the hydraulic load and the fluid storage vessel that bypasses the spool valve. Fluid flow may encounter less resistance through the bypass line, such that the hydraulic system may run more efficiently and with a reduced risk for cavitation in the hydraulic load.
摘要:
A hydraulic control system for a machine is disclosed. The hydraulic control system may have a pump configured to pressurize fluid, and a motor driven by a flow of pressurized fluid from the pump. The hydraulic control system may also have a first accumulator configured to receive pressurized fluid discharged from the motor and to selectively supply pressurized fluid to the motor, and a second accumulator configured to receive pressurized fluid discharged from the motor and selectively supply pressurized fluid to the motor.
摘要:
Provided is a hydraulic drive apparatus for working machine capable of preventing an excessive pressure drop on a meter-in side and moving a load in a lowering direction at a stable speed requiring no counter balance valve, including a hydraulic pump, a first hydraulic actuator lowering a first load, an operating device, a first hydraulic circuit including meter-in and meter-out flow passages, a control valve, a meter-in-flow-rate controller, a meter-out-flow-rate controller making a meter-out flow rate not lower than a meter-in flow rate, a second hydraulic actuator, a second hydraulic circuit between the first hydraulic circuit and a tank and for the second hydraulic actuator, a back pressure valve between the second hydraulic circuit and the tank, a regeneration line leading a part of hydraulic fluid from between the second hydraulic circuit and the back pressure valve to the meter-in flow passage, and a check valve in the regeneration line.
摘要:
A closed-loop system includes a pump driving a fluid through a series of conduits. A control system is included that minimizes pressure fluctuations in a bootstrap reservoir to maintain a desired minimum pressure at the pump inlet. Moreover, the control system reduces a maximum system pressure by reducing the magnitude of pressure fluctuations encountered by the bootstrap reservoir.
摘要:
A valve assembly includes a valve housing defining a service passage, a first bore in fluid communication with the service passage, a first passage, a second bore in communication with the service passage and a second passage. The first bore has an inlet portion, a first service portion in communication with the service passage, and a first load holding portion. The first passage is in communication with the first load holding portion and the service passage. The second bore has a return portion, a second service portion in fluid communication with the first service passage, and a second load holding portion. The second passage is in selective communication with the second load holding portion of the second bore and the return passage. A valve is disposed in the second passage. The valve allows fluid to flow only in a direction from the second load holding portion to the return passage.
摘要:
A rotation control system of a hoist pump includes: the hoist pump (3); an engine (2) for driving the hoist pump (3); a working equipment driven by a hydraulic cylinder that is extendable by hydraulic oil delivered through the hoist pump (3); a hydraulic oil tank that stores the hydraulic oil supplied to the hoist pump (3) and receives the hydraulic oil returned from the hydraulic cylinder; and a controller (9) that controls a rotation speed of the hoist pump (3) to be an allowable rotation speed that is set in advance for preventing cavitation while the hydraulic cylinder is operated.
摘要:
A metering valve for a work machine hydraulic system is disclosed. The metering valve has an inlet and an outlet, a main poppet, and a solenoid-operated pilot element. The main poppet is movable to pass fluid from the inlet to the outlet, and to block fluid from the inlet to the outlet. The solenoid-operated pilot element is movable between a first position at which pressurized fluid from the inlet pressurizes a control chamber in communication with a control end of the main poppet to urge the main poppet toward the flow-blocking position, and a second position at which the control chamber is communicated with a drain to move the main poppet toward the flow-passing position. The metering valve also has a relief valve element configured to drain pressurized fluid from the control chamber to move the main poppet toward the flow-passing position in response to a pressure at the inlet exceeding a predetermined pressure.
摘要:
A spool-type hydraulic directional control valve having improvements to reduce cavitation when the spool is in the float position. The flow area of a first passageway on the valve spool is appropriately sized to reduce the flow hydraulic fluid flow from the head end of the hydraulic cylinder to the hydraulic fluid reservoir, such that a sufficient proportion of that hydraulic fluid instead flows internally through control valve and back to the rod end of the hydraulic cylinder to reduce cavitation when the valve spool is in the “float” position. Additionally, a second passageway on the valve spool may be blocked-off, eliminating the hydraulic fluid flow path from the hydraulic fluid reservoir to the rod end of the hydraulic cylinder when the valve spool is in the “float” position.
摘要:
A fluid circuit for raising and lowering an implement including a quick drop valve member movable between at least a first position and a second position, the first position corresponding to a non-quick drop hydraulic fluid flow path of the fluid circuit and the second position corresponding to a quick drop hydraulic fluid flow path of the fluid circuit, the quick drop valve member being movable between at least the first and second positions based on pressures in the fluid circuit produced by hydraulic fluid. The fluid circuit further including a control system configured to selectively apply a biasing force against the quick drop valve member biasing the quick drop valve in the first position, the control system providing the biasing force independent of pressures in the fluid circuit produced by the hydraulic fluid.
摘要:
A hydraulic valve system (1) has a supply connection arrangement, having a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement, having two working connections (A, B), which can be connected with a hydraulic motor (2), and a directional valve (4) between the supply connection arrangement (P, T) and the working connection arrangement (A, B), which is connected with the working connection arrangement (A, B) via working lines (17, 18), in which are arranged check valves (21, 22), which can be opened by means of pressure.