Pressure compensated electromagnetic proportional directional flow control valve

A pressure compensated electromagnetic proportional directional flow control valve integrally comprising:

• an electromagnetic proportional directional flow control valve configured to be driven by a solenoid;
• and
• a pressure compensated valve configured to carry out pressure compensation of a flow rate controlled by the electromagnetic proportional directional flow control valve, wherein:
• the electromagnetic proportional directional flow control valve includes:
• an introducing port to which a liquid is introduced from the pressure compensated valve;
• first and second external connection ports which are communicated with an external liquid-pressure actuator;
• a return port which is communicated with a tank;
• a directional flow control spool configured to control passages extending among the above ports;
• a first variable aperture which is formed on the passage extending between the introducing port and the first external connection port by movement of the directional flow control spool;
• and
• the pressure compensated valve includes:
• a liquid-pressure supply port which is communicated with an external liquid-pressure source;
• a derivation port through which a liquid from the liquid-pressure supply port is introduced to the introducing port;
• a branch port through which a surplus liquid of the liquid flowing from the liquid-pressure supply port to the derivation port flows out to outside;
• a pressure compensation spool configured to control passages extending among the above ports;
• a spring configured to bias the pressure compensation spool in a bias direction;
• a first pressure chamber configured to bias the pressure compensation spool in a direction opposite the bias direction of the spring;
• a second pressure chamber configured to bias the pressure compensation spool in a direction that is the same as the bias direction of the spring;
• a first pressure passage through which pressure existing upstream of the first variable aperture is introduced to the first pressure chamber;
• and a second pressure passage through which pressure existing downstream of the first variable aperture is introduced to the second pressure chamber;
• and
• wherein the electromagnetic proportional directional flow control valve includes a connection passage, which causes the return port to be communicated with the second pressure passage when the directional flow control spool is located at a neutral position where communication between the introducing port and the first external connection port and communication between the introducing port and the second external connection port are blocked;
• and
• in a case where the directional flow control spool moves to the neutral position, pressure of the second pressure chamber is reduced to tank pressure, and the liquid supplied to the liquid-pressure supply port does not flow to the derivation port but flows out from the branch port;
• and
• wherein the connection passage is formed to extend through an inside of the directional flow control spool;
• both ends of the connection passage respectively open on outer surfaces of two lands of the directional flow control spool;
• and
• these lands also serve to open and close the passages extending among the above ports.