초록 ▼

A fluid power system including a fluid power cylinder having a piston and fluid ports at its opposite ends, a directional valve for selecting the direction of piston actuation, and a metering control valve coupled between the directional valve and the cylinder. The control valve includes a cylinder

A fluid power system including a fluid power cylinder having a piston and fluid ports at its opposite ends, a directional valve for selecting the direction of piston actuation, and a metering control valve coupled between the directional valve and the cylinder. The control valve includes a cylinder section having a control piston therein and a valve body connected to the cylinder section and having a valve spool-receiving cavity therein. The valve body has first and second fluid ports therein communicating with the cavity, one of the valve body ports being coupled to one of the power cylinder ports and the other being coupled to the directional valve. A valve spool is disposed in the valve body cavity operatively connected to the control piston and movable therewith, the spool having a passage therein. The spool passage communicates with the valve body ports and provides unrestricted fluid flow therebetween in a first spool position and substantially restricts fluid flow between the valve body ports in a second spool position, movement of the spool between its positions progressively metering the fluid flow between unrestricted and substantially restricted conditions. The spool passage is arranged so that with the spool in one of its positions fluid under pressure entering the passage from one of the valve body ports moves the spool and the control piston in one direction to the other position thereby providing the metering operation. The cylinder section has a port for admitting fluid under pressure thereto so as to move the control piston and spool in the direction opposite the one direction.

대표청구항 ▼

In a fluid power system wherein changes in flow rate may occur, said system including a hydraulically actuable device having first and second ports each functioning as inlet and outlet ports, respectively, and a directional valve for selecting the direction of actuation of said hydraulically actuabl

In a fluid power system wherein changes in flow rate may occur, said system including a hydraulically actuable device having first and second ports each functioning as inlet and outlet ports, respectively, and a directional valve for selecting the direction of actuation of said hydraulically actuable device: a metering control valve including a cylinder section having a control piston therein; a valve body connected to said cylinder section and having a valve spool-receiving cavity therein, said valve body having first and second axially spaced ports therein communicating with said cavity, one of said valve body ports being coupled to one of said ports of said hydraulically actuable device and the other of said valve body ports being coupled to said directional valve for selectively coupling said other valve body port to a source of fluid under pressure and a sump; a valve spool in said cavity operatively connected to said control piston and movable therewith between first and second spool positions, said spool having a passage therein extending in the direction of spool movement, said passage communicating with said valve body ports and providing unrestricted fluid flow therebetween in said first spool position, said spool substantially restricting fluid flow between said valve body ports in said second spool position, movement of said spool between said positions thereof progressively metering said fluid flow between unrestricted and substantially restricted conditions, said passage having a surface arranged so that with said spool in one of said positions thereof fluid under pressure entering said passage from one of said valve body ports acts on said surface thereby moving said spool and control piston in one direction to the other of said positions thereof; said cylinder section having a control cylinder port for admitting fluid under pressure thereto thereby to move said control piston and spool in the direction opposite said one direction and for discharging fluid therefrom when said piston and spool are moved in said one direction; and means for metering fluid discharged from said control cylinder port thereby controlling movement of said control piston and spool in said one direction.