摘要:
A hydrostatic drive includes a hydraulic machine, a hydraulic adjusting device, a high-pressure accumulator, an accumulator-closing valve, and an electronic control unit. The hydraulic machine has a swept volume that is adjustable via the hydraulic adjusting device from a maximum positive swept volume to a maximum negative swept volume via a zero swept volume. The hydraulic machine is operated as a pump with positive swept volume and as a motor with negative swept volume. The high-pressure accumulator supplies the hydraulic machine with pressure medium for operation as a motor via a pressure line. The accumulator-closing valve has a first position and a second position and is arranged in the pressure line. A fluidic connection from the high-pressure accumulator to the hydraulic machine is open in the first position and closed in the second position. The accumulator-closing valve is actuated in accordance with signals from the electronic control unit.
摘要:
The invention relates to a proportional directional control valve for controlling a hydraulic consumer, having a housing with a pressure port, a tank port, and first and second working ports. A control element is movably mounted in the housing. A single actuator is provided for moving the control element, which, in dependence on its position relative to the housing, enables different flow paths between the ports. The control element, starting from a first switching position in which both working ports are connected to the tank port, is movable by the actuator via a second switching position that follows the first switching position, to a third switching position that follows the second switching position. It is possible, by moving the control element from the first switching position into the third switching position, to successively disconnect the two working ports from the tank port and connect them to the pressure port.
摘要:
A hydraulic load-sensing control arrangement for a first and second hydraulic consumer has a variable displacement pump having load-sensing regulation, to which the highest respective load-sensing pressure of consumers is reported. The first consumer has the highest load pressure in normal operation and therefore the highest load-sensing pressure dependent on the load pressure. A pressure reducing valve is arranged in the pressure medium flow path between the variable displacement pump and the first consumer. A spring force from a regulating spring and a regulating pressure dependent on the load pressure of the first consumer are applied in the opening direction of a valve gate in this pressure reducing valve and pressure is applied directly downstream from the pressure reducing valve in the closing direction thereof. A pressure equivalent of the spring force of the regulating spring and the regulating pressure are greater than a pressure of the variable displacement pump.
摘要:
The invention relates to a proportional directional control valve for controlling a hydraulic consumer, having a housing with a pressure port, a tank port, and first and second working ports. A control element is movably mounted in the housing. A single actuator is provided for moving the control element, which, in dependence on its position relative to the housing, enables different flow paths between the ports. The control element, starting from a first switching position in which both working ports are connected to the tank port, is movable by the actuator via a second switching position that follows the first switching position, to a third switching position that follows the second switching position. It is possible, by moving the control element from the first switching position into the third switching position, to successively disconnect the two working ports from the tank port and connect them to the pressure port.
摘要:
Provided is a load sensing system for controlling a discharge pressure of the hydraulic pump so as to render a differential pressure obtained by subtracting a maximum load pressure among the hydraulic actuators from a discharge pressure of the hydraulic pump to be a constant pressure, and there are provided: a first load pressure flow passage which introduces load pressures of the hydraulic actuators to be outputted to a PLS transmission line which transmits the maximum load pressure among the hydraulic actuators at the time of activating the hydraulic actuators; and a second load pressure flow passage which is a flow path for introducing the load pressures of the hydraulic actuators to be outputted to the PLS transmission line during operation after activations of the hydraulic actuators, and wherein a flow rate of the pressure oil therein is reduced than that in the first load pressure flow passage.
摘要:
Disclosed is a lifting gear valve arrangement for controlling a double-action lifting gear or an add-on unit with a continuously adjustable directional control valve and with an individual pressure compensator via which a pressure medium volume flow to and from a lifting cylinder of the lifting gear can be controlled. A proportionally adjustable pressure limiting valve is provided in the pressure medium flow path between an outlet connection of the directional control valve and a working connection of the lifting gear valve arrangement, via which the pressure inside this area can be limited to a maximum value. The adjustment of the pressure limiting valve is preferably performed as a function of the operating states of the lifting gear or of the type of add-on unit.
摘要:
A hydraulic system for a machine is disclosed. The hydraulic system has a source of pressurized fluid and a fluid actuator with a first chamber. The hydraulic system also has a first valve configured to selectively fluidly communicate the source with the first chamber. The first valve further includes a first element movable between a flow passing, at which fluid from the source flows to the first chamber, and a flow blocking position, at which fluid from the source is blocked from the first chamber and a second element configured to selectively drain a control passageway associated with the first element to cause the first element to move. The hydraulic system further has a proportional pressure compensating valve configured to control a pressure of a fluid directed between the source and the first valve dependent upon the pressure of the control passageway.
摘要:
A hydro-pneumatic system has an air powered motor driving a hydraulic pump with a pressure limiting valve that turns off air flow to the air motor when a hydraulic pressure output by the pump at a sense port of the valve reaches a certain limit. A valve element of the valve has spring, hydraulic and pneumatic sections, with an unbalanced area of the hydraulic section in a sealed pressure chamber of a cartridge that is part of the valve housing. The pneumatic section extends out one end of the cartridge to fill a bore between the air inlet and outlet ports when the pneumatic section is extended, and allow air to pass when it is retracted.
摘要:
An anti-saturation valve assembly (51) for use in a hydraulic system having priority (17) and auxiliary (25) load circuits, the priority circuit providing a priority load signal (19). The anti-saturation valve assembly includes a pressure sensor portion (61) which senses a decrease between pump pressure (23) and the priority load signal (19), and generates a force on a pressure reducing portion (63) to reduce, correspondingly, a pilot pressure (59): The reduced pilot pressure to a pilot valve (35) results in reduced flow to a pilot-operated main control valve (27) in the auxiliary load circuit (25), thus providing anti-saturation protection for the circuit, without throttling a main flow path and wasting substantial hydraulic power.
摘要:
A hydraulic system for excavators or other working machines, comprising a branching device for feeding special consumers with particularly high power consumption. The special consumer is supplied with priority until a maximum supply level is reached, which is lower than the maximum output of the hydraulic source. The remaining output difference is made available without restriction to the other consumers in the hydraulic system, wherein the distribution of the remaining flow of hydraulic fluid is not influenced. Thus, the operating ability of the machine equipped with the hydraulic system is maintained completely and in the standard manner. Any possible slow-down of the adjustment movement of a consumer is reflected proportionally in the movements of all other consumers, so that the ratios of the operating speeds or reaction speeds of the individual consumers among themselves remain the same.