摘要:
A fluid control system including a variable displacement pump having a load system control and configured to operate in an open center mode. A pump control is operable between a first arrangement and a second arrangement. The pump control receives pressurized fluid from a first load sensor pressure in fluid communication with the pump and an actuator return pressure in fluid communication with an actuator configured to operate using pressurized fluid from the system, the pump control providing a selective pump control pressure to the pump load system control. When the system is operating in a standby mode, the pump operates in a first minimized displacement condition. When the system is in a stall mode, the pump operates in a second minimized displacement condition.
摘要:
A pump control assembly having a flow control assembly disposed between the first end of a load sensing valve and a fluid pump is disclosed. The flow control assembly may include an orifice, a first valve assembly, and a second valve assembly. When the first valve assembly is in an open position and the second valve assembly is in a first position, fluid passing through the orifice is directed to a fluid reservoir and to the load sensing valve. When the first valve assembly is in a closed position and the second valve assembly is in a second position, all fluid passing through the orifice is directed to the load sensing valve. An electronic controller can be configured to transmit an output current to the first and second valve assemblies in response to an operational parameter of a prime mover supplying power to the fluid pump.
摘要:
A valve block includes a plurality of control valve disks that form a first block part and a second block part. A supply pressure for the control valve disks of the first block part is limited by a common pressure-limiting valve. The common pressure-limiting valve is arranged such that a prevailing load pressure registered by the control valve disks does not exceed a specific value. The supply pressure for the control valve disks of the second block part is not limited.
摘要:
A hydraulic system for an operator controlled machine, the system including at least one actuator for moving a machine component, a source of pressurized fluid for delivering pressurized fluid at a system pressure to a control valve which is operable under operator control, to control the flow of fluid from the source to the actuator at a load pressure, along a load pressure path, a flow control apparatus for controlling the flow of fluid from the source to the control valve, the flow control apparatus including an actuating part which is biased by a resilient device to a condition in which the flow control apparatus provides for a maximum flow of fluid to the control valve, actuating part movement by the resilient device being resisted by system pressure fluid and being supported by fluid at a control pressure, the control pressure being derived from the load pressure, and wherein the system includes a pressure control device to which the load pressure is communicated, the pressure control device being operated under operator control either to deliver the control pressure to the flow control device at load pressure or a modified pressure which is less than the load pressure.
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:
A method includes providing a hydraulic pump with an outlet, a main orifice having an inlet communicating with the pump outlet, and a main orifice outlet. Further provided are a flow orifice, an amplification orifice, and an amplification orifice outlet, means for generating an output signal representative of a fluid pressure, and a pump controller for controlling the hydraulic pump in response to the output signal. The flow orifice and the amplification orifices each define an area, with these areas defining a ratio, and with the main orifice and the ratio being variable. The method includes operating the system in a first mode so as to define a first mode ratio and operating the system in a second mode so as to define a second mode ratio, so that the ratio is controlled differently in the first mode and the second mode.
摘要:
The invention concerns a hydraulic valve arrangement (1) with a supply connection arrangement comprising a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement comprising two working connections (A, B), which can be connected to a motor (4), a directional valve arrangement (5) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a compensation valve (15) acted upon in a first activation direction by a pressure in a first pressure chamber (33), which is connected to a load-sensing pipe (LS), and, if required, by a spring (32), and in a second activation direction opposite to the first activation direction by a pressure downstream of the directional valve arrangement (5), said pressure acting in a second pressure chamber (34), the compensation valve (15) having an inlet (14) and an outlet (19). In connection with a post-compensated valve, it is endeavored to adjust the load pressures at the working connections (A, B) in dependence of the direction. For this purpose, each working connection (A, B) is connected to a control system, which amplifies the effect of the pressure in the first pressure chamber (33) on the compensation valve (15) in dependence of a pressure ruling at the working connection (A, B).