摘要:
A shuttle valve connects a second flowpath and a drain flowpath when the hydraulic pressure in a first flowpath is greater than the hydraulic pressure in the second flowpath. The shuttle valve connects the first flowpath and the drain flowpath when the hydraulic pressure in a second flowpath is greater than the hydraulic pressure in the first flowpath. The ratio between the pressure receiving area of a first pressure section and the pressure receiving area of a second pressure section is the same as the ratio between the pressure receiving area of a first chamber side and the pressure receiving area of a second chamber side of a cylinder rod.
摘要:
A railcar damping device includes: a tank storing a liquid; a first opening/closing valve provided in a first passage connecting a rod side chamber and a piston side chamber, which are defined by a piston, to be capable of opening and closing the first passage; a second opening/closing valve provided in a second passage connecting the piston side chamber and the tank to be capable of opening and closing the second passage; a pump that is driven to rotate at a predetermined normal rotation speed in order to supply the liquid from the tank to the rod side chamber; and a temperature determination unit that determines a temperature of the liquid supplied to the actuator, wherein a rotation speed of the pump is reduced below a normal rotation speed when the temperature determination unit determines that the temperature of the liquid is lower than a predetermined temperature.
摘要:
A shovel includes a plurality of hydraulic actuators including a first hydraulic actuator and a second hydraulic actuator, a main pump, a hydraulic pump-motor configured to function as a hydraulic motor by using hydraulic oil flowing out of the first hydraulic actuator and configured to function as a hydraulic pump, a control valve configured to control a flow of the hydraulic oil in the plurality of hydraulic actuators, a first oil passage to connect the main pump with the second hydraulic actuator through the control valve, and a second oil passage to connect the hydraulic pump-motor with the second hydraulic actuator. The second oil passage meets the first oil passage between the control valve and the second actuator.
摘要:
An improvement to the component based hydraulic systems is an integrated electro-hydraulic actuator (EHA) that contains all components necessary to achieve power up, gravity return actuation of a lift mechanism such as the forks of a pallet truck. Further, improvements to known power-up, gravity-down component-based hydraulic circuits are described herein. The improvements provide for power up, gravity return functionality with fewer components as compared known systems. Finally, a method for controlling the EHA and/or hydraulic circuits described above is detailed herein and provides a user with maximum control of a lift mechanism during lower or “down mode,” but also provides for the least amount of energy consumption by the actuator.
摘要:
A hydraulic drive system realizes a jack-up operation without arrangement of a flow rate control valve and center bypass selector valve. The hydraulic drive system has first and second hydraulic pumps, first and second directional control valves for controlling boom cylinders, a third directional control valve for controlling the boom cylinders, and a third hydraulic pump for feeding pressure oil to the third directional control valve. A jack-up selector valve has a second select position where, when a pressure in bottom chambers of the boom cylinders is not higher than a predetermined pressure, feeding of pressure oil, which is delivered from the first hydraulic pump and second hydraulic pump, to rod chambers of the boom cylinders, is held permissible in association with switching of the second directional control valve and third directional control valve by a manipulation of a control device.
摘要:
A hydraulic ride control system for mobile machine having an implement is disclosed. The ride control system may include a hydraulic actuator extending from the machine and connected to an implement, an accumulator, a valve controlling fluid flow between the hydraulic actuator and the accumulator, a sensor, a ride control selection switch and, a controller receiving signals from the sensor and the ride control selection switch and when the ride control switch is in manual position, only allowing fluid flow between the hydraulic actuator and the accumulator when the sensor indicates a predetermined value.
摘要:
A method, system and apparatus including a mechanism capable of performing a variety of operations, each operation having a respective power requirement and a power source capable of providing power to the mechanism at a variety of different levels corresponding to the operations being undertaken by the mechanism where the power source is regulated to at least provide a first lower power level sufficient for one or more operations requiring a lower power level and is increased to provide a higher power level as needed for one or more alternative operations requiring a higher power level.
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).
摘要:
The invention relates to a hydraulic control arrangement and to a method for controlling a hydraulic consumer that comprises a pressure chamber on the input side and on the return side, said pressure chamber being connected to an adjusting pump or a tank via a valve device. The valve device is controlled by means of a control unit via which it can be adjusted in a regeneration mode, in which both pressure chambers are connected to the adjusting pump. According to the invention, the adjusting pump is pressure controlled, whereby in the regeneration mode, it is automatically switched to the normal operation in which the supply side of the pressure chamber is connected to the adjusting pump and the return side of the pressure chamber is connected to the tank when the pumping rate falls below the demand for the pressure medium.
摘要:
A valve positioner system with zero bleed at steady state is disclosed. The system has a pilot valve, the operation of which is controlled by an electronic circuit powered from a signaling and power connection of a positioner device. A plurality of pneumatic valves are activated and deactivated by the pilot valve to control a valve actuator. With varying configurations and arrangements of normally open or normally closed pilot valves and pneumatic valves, fail freeze and fail safe operations are contemplated. The activation and deactivation of the pilot valve is controlled by an electronic circuit that monitors a valve position signal.