摘要:
A system and method for controlling an electro-hydraulic valve arrangement to provide make-up fluid to a hydraulic actuator are disclosed. The system includes an electro-hydraulic valve arrangement actuated by a control lever and disposed between a pump having a stand-by pressure and a hydraulic actuator. A pressure, representative of the fluid in the hydraulic actuator, is sensed and compared to the stand-by pressure of the pump. The control of the control lever over the electro-hydraulic valve arrangement is overridden when the difference between the pump stand-by pressure and the pressure of the fluid in the hydraulic actuator is greater than a predetermined pressure limit.
摘要:
A method and system for determining the actuating pressure of a servo cylinder that is actuated by pressurized fluid. The actuation displacement of the servo cylinder is obtained from a sensor or other device. A pressure sensor measures inflow pressure at one point of a pressurized fluid line supplying the servo cylinder. The actuating pressure is determined based on the inflow pressure and the change in the actuation displacement of the servo cylinder.
摘要:
An input/output valve switching apparatus of a semiconductor manufacturing system minimizes a vibration set up while operating an input/output valve for opening and closing a wafer-transfer passage that connects chambers of the system. The switching apparatus includes a valve actuator having a close port and an open port, a first fluid line connected to the close port, a second fluid line connected to the open port, first flow regulators installed in the first and second fluid lines, respectively, to regulate the flow rate of fluid, and second fluid flow regulators installed in the first and second fluid lines to regulate the flow rate of the fluid that has passed. The second fluid flow regulators can prevent a rapid introduction of the fluid into the actuator. SEC.928
摘要:
In one aspect of the invention, the hydraulic system provided with the hydraulic pressure source and at least one meter-in spool valve. Each Spool valve has an inlet and an outlet. A hydraulic actuator is fluidly coupled with the spool valve outlet. A load hold check valve fluidly interconnects the pressure source with at least one spool valve inlet. The load hold check valve has a pressure control chamber. A three way valve has a first port in fluid communication with the pressure control chamber, a second port in fluid communication with at least one spool valve inlet, and a third port in fluid communication with the pressure source. Proved pressure and flow control to an actuator are provided, and make-up and line relief are provided without the use of an additional spool valve.
摘要:
A hydraulic drive and fluid control system for a mechanism having at least two fluid actuated cylinder includes a bi-directional motor/gear pump. A monolithic block manifold has intersecting bores formed therein in which valving and control mechanism for the fluid circuit is mounted. The fluid control system includes a variety of elements for providing smooth action of the cylinders at start, stop, and intermediate operations. These include piston-style accumulators, self-actuating fluid flow rate control valves and cushion valves.
摘要:
A hydraulic system comprises a variable displacement pump. The hydraulic system includes a first device capable of being hydraulically powered by the pump and a reversing device adapted to cause the first device to autoreverse. The hydraulic system also includes an isolation device adapted to prevent pressure surges resulting from a source other than the first device from actuating the reversing device, thereby preventing undesirable autoreversing of the first device.
摘要:
An assembly of a pair of electrically operated bidirectional proportional control valves and a four-way direction control valve governs the flow of fluid to and from a hydraulic cylinder. The four-way direction control valve alternately connects a pump supply line to one of a pair of intermediate conduits and a tank return line to the other intermediate conduit. That connection determines the direction of movement of the cylinder piston. The intermediate conduits are coupled to chambers of the cylinder by a separate one of the proportional control valves which meters the fluid flow to or from the respective chamber. Thus the proportional control valves control the rate of piston movement.
摘要:
A hydraulic control apparatus for a hospital bed includes a manifold having a manifold block with an inlet, an outlet, and a conduit in fluid communication with the inlet and the outlet, and a valve assembly having a valve with a portion moveable within the conduit between a first position blocking fluid communication between the inlet and the outlet and a second position in which the inlet is in fluid communication with the outlet. The control apparatus further includes a solenoid operable to move the valve from the first position to the second position in response to an electrical input applied to the solenoid, and a lever operable to move the valve from the first position to the second position in response to a manual input applied to the lever.
摘要:
The invention concerns a hydraulic circuit (17) and a control valve (18) dimensioned to be capable of providing the greater part the control surface (3) actuating, which requires less power than the system maximum performances Moreover, a bi-directional hydraulic pump (23), driven by an electric motor (24), can supply backup power which added to said circuit (17) power can ensure said maximum performances.
摘要:
The present invention concerns a method for controlling the speed of motion of a hydraulically operated machine, an operating system and a control device of the machine. The flow line (3) of the medium from the pump (2) to the machine (1) is divided into two branches (10, 11). By means of a valve (8), the second branch (11) can be set to feed medium either to the machine (1) or to return the medium to the tank (4) of the pump. Such a flow is led to the second valve (8), that at a speed of rotation of the pump lower than the highest speed of rotation, the difference between the flow supplied by the pump and the flow through the second branch produces the desired slowest speed on motion of the device. When the valve (8) is set to return the medium to the tank (4) of the pump, the flow from the pump (2) is adjusted by changing the speed of rotation of the pump.