Fluid valve arrangement

摘要

A pressure controlling valve includes a slidable spool arranged to be spring loaded towards a neutral position. A first port and a second port are connected to allow a fluid flow through the valve. A first and a second pilot port are connected to a cavity adjacent a respective first and second end surface of the spool. The pilot ports are connected to a fluid conduit on either side of a fluid device causing a pressure drop in the fluid conduit and the fluid device is connected to one of the first or second ports. The spool is displaced against the spring load in response to a pressure difference between the first and the second pilot port, whereby a control surface of the spool is arranged to restrict the fluid flow through the valve when the control surface approaches a central cavity.

主权项

1. A fluid valve arrangement comprising:
a fluid conduit arrangement having a first conduit and a second conduit, the first conduit being connectable with a supply of fluid pressure and the second conduit being connectable with a hydraulic consumer; wherein the fluid valve arrangement includes a pressure controlling valve with a valve body having a slidable spool arranged to be spring loaded towards a neutral position in the valve body, a first port and a second port for a fluid, the first and second ports being connected to allow a fluid flow between the first port and the second port, a first pilot port connected to a cavity adjacent a first end surface of the spool, and a second pilot port connected to a cavity adjacent an opposite, second end surface of the spool, wherein the spool comprises a first control surface and a second control surface located in a first cavity and a second cavity, respectively, which first cavity and second cavity each has a cross-sectional area that is larger than the cross-sectional area of the spool; that the first cavity and the second cavity are connected by a third cavity, that the spool is operable to be displaced in response to a pressure difference between the first pilot port and the second pilot port that exceeds a predetermined value; and that the first control surface or the second control surface is arranged to restrict the fluid flow through the valve when the first control surface or the second control surface approaches the third cavity when the spool is displaced from the neutral position; a fluid device causing a pressure drop between the first and second fluid conduits, which fluid device is connected to one of the first and second ports of the pressure controlling valve, and that the pilot ports of the pressure controlling valve are connected to the fluid device, wherein the pressure controlling valve is arranged to control the pressure drop across the fluid device irrespective of the direction of fluid flow, the fluid device including a pair of controllable two-way valves connected in parallel; an electronic control unit (ECU) for controlling at least the fluid device; and an opening degree sensor which determines the position of the spool, the sensor being connected to the ECU.